Resistance welding is used to create strong metal joints of alloys, dissimilar and homogeneous materials at the level of interatomic bonds. During this process, an electric current heats up the metal until plastic deformation occurs, and the connection itself occurs due to additional pressing of the parts together. One of the options for spot welding is capacitor welding. The main difference between this process and others is the way of storing energy for melting the metal. Capacitor welding is carried out using the energy previously stored on the capacitors.

The main parts of the equipment will be one or more capacitors, which accumulate charge due to the input from a constant voltage source. When a certain level of charge is reached, the electrodes from the capacitors are connected to the welding points. The electric current causes the surface to heat up quickly and strongly, melting the metal and forming a turned weld. Usually, each capacitor discharge lasts only 1-3 milliseconds, due to this, heating outside the zone itself practically does not occur.

Capacitor Welding Applications

Modern automatic production facilities are capable of creating up to 600 battery discharges and connection points per minute with strict adherence to the quality characteristics of welding and the repeatability of all manipulations. At the same time, the equipment does not require consumables in the form of electrodes (as for inverter welding) or welding wire (as for argon arc welding). In addition, no coolant is required for the work.

With the help of capacitor welding in electronics, you can connect parts that are afraid of overheating and cannot be bonded with ordinary fluxes. This type of welding can be used for microscopic elements.

Capacitor welding is especially in demand in car body repair. The discharge does not deform the walls of the parts and does not burn them, so there is no need for straightening.

On a note. This type of welding is used for the repair and creation of jewelry, in the manufacture of watches, cinema, and photographic equipment.

Capacitor welding has certain disadvantages, the main of which is impulse loading. This load occurs in the network with a rapid discharge of capacitors. Such pulses create interference and can damage all equipment.

Types of welding

The discharge from the capacitors can be immediately sent to the welding site or done through the secondary winding of the capacitor. In the first case, the welding will be called transformerless, and in the second, transformer. The first option is used for joining, and the last option is used when creating seams and in spot work.

In shock-capacitor welding, the parts are connected during the impact of the capacitor through current-collecting contacts, and in some cases these contacts may be the parts themselves.

Let us consider how this process takes place when studs are welded, which will simultaneously play the role of current-collecting contacts. First, it is necessary to ensure that the end of the hardware touches the surface with which it should be connected. Then, through the hardware, a capacitor discharge is supplied to the welding area. As a result, a micro-arc is formed and the temperature rises significantly. The place of contact between the stud and the surface of the part melts. With the help of pressure, the hardware is immersed in the molten layer. Then the alloy cools down and simultaneously hardens, and the hardware is welded.

In transformer welding, the capacitor, after charging, is connected to a step-down transformer along the primary winding. A potential appears on the secondary winding that is less than the incoming pulse. Next comes the discharge, the capacitor starts charging again, and the energy goes through the primary winding of the transformer. Then the whole process is repeated. This technology makes it possible to make precise welds by performing several cycles of operations up to 5 discharges per second.

For household appliances, transformer welding is usually used, because transformerless equipment is more bulky. Only one battery of capacitors should have a capacity of about 100 thousand microfarads. An ultracapacitor can be used for these purposes - this is a supercapacitor, comparable in size to a conventional electrolytic one, but with a much larger capacity. However, the use of a supercapacitor leads to a significant increase in the cost of equipment. Therefore, the transformer welded version is preferable.

In modern equipment, the power and discharge frequency of the capacitors are regulated through PIC controllers. All manipulations are controlled through a computer, and most of the processes are automated. To work on such equipment, you need not only to read the full description, but also to take training courses.

Homemade capacitor welding

There are different options for creating homemade welding machines. Simple DIY spot welding can be done using a spotter, a device used in car body repairs. In appearance, this equipment is a power unit, to which electrodes or a welding gun are attached using a flexible hose.

In order to assemble such a welding machine, you will need:

1. Transformer 5-20 W for 220 V with an input voltage of 5 V - 1 piece;
2. Transformer not less than 1000 W - 1 piece;
3. Rectifier diodes with direct current up to 300 mA - 4 pieces;
4. Electrodes (if you have one, you can take a welding gun);
5. Thyristor KU 202 or T142-80-16 (outdated version of PTL-50 on the diagram) - 1 piece;
6. Electrolytic capacitor 1000.0 x25 V - 1 piece;
7. Copper wire with a cross-section of 35mm2 - at least 1 meter.

Fuses and switches are also needed, and if desired, a housing.

Note! In this circuit, you can use a transformer from a microwave oven, but this device needs to be redone by removing the magnetic shunts and the secondary winding. Next, at the site of the secondary winding, make several turns of copper wire. Then, changing the number of turns, you need to adjust the operation of the device.

How does capacitor welding do it yourself? There are 2 main nodes in the spotter design:

1. relay with thyristor V9;
2. welding transformer T2.

The winding is connected through a diode bridge V5-V8, into which an electronic relay is diagonally connected. During operation in the "on" position at the switch S1, the voltage from the power source goes to the primary winding of the transformer T1. This charges the capacitor. In this case, the winding of the transformer T2 is de-energized, and the thyristor V9 is closed. When you press the button S3, the charge from the capacitor through the variable resistor R1 goes to the control electrode of the thyristor V9. The current breaks off the thyristor, the voltage goes through the primary winding of the transformer T2, a powerful pulse with a duration of about 0.1 seconds arises in the secondary winding. At the end of the discharge of the capacitor C1, the system returns to its original state.

Attention! During the discharge, the current is 350-500 A. Use a homemade spotter with extreme caution.

This device can be used for small welding works; it will not work to connect fittings or pipes with it.

Video

Capacitor welding is a technology for creating a seamless connection of metal products. Connections are made by short-term pulses of electrical energy.

The molten metal and filler material are mixed, after solidification is formed Weld... In the process of performing work, the welder is exposed to intense exposure to ultraviolet radiation, which has Negative influence on the human body.

Unlike this method, capacitor welding is not harmful to health, therefore, a minimum set of personal protective equipment is not required to perform the work. Due to the accuracy of the devices, after connecting the elements, practically no traces remain on the surface. Rational use energy saves electricity.

Modern science does not have the ability to create massive apparatus, therefore, at present, capacitor spot welding is used to join compact elements.

Point method principle

The connection technological process is as follows:

1. Two workpieces are connected with two conductors to create a closed circuit.
2. Capacitors store the required amount of energy from the mains supply.
3. The conductors receive a short-term charge, under the influence of which the contact area melts, forming connections.

The method allows you to connect products that differ in the type of metal. However, the thickness of one of the elements should not exceed 0.15 cm.

The work does not require the use of any consumables. The melt zone consists exclusively of the alloy of the workpieces.

Requirements

To obtain a high-quality result, the following requirements must be observed:

1. The duration of the working cycle does not exceed 3 ms.
2. Capacitors get their operating energy level in a short amount of time.
3. As a preliminary preparation, cleaning from dirt and degreasing of the surface is carried out.
4. Copper rods are best suited for the role. Their thickness is three times greater than the thinnest point of the workpiece.
5. At the moment of contact, the elements to be connected must be tightly pressed against each other. After the discharge, a short period of time is required for the compound to crystallize, so the electrodes are disconnected with a short delay.

Varieties

There are several technological methods for performing capacitor resistance welding. Let's consider them in more detail.

Point

The method is intended for joining products with different dimensions, for example, thin wire and sheet of metal... The connection is made by a short current pulse stored in the capacitors. It is widely used in the electrical industry.

Roller

In this case, the seam consists of many point joints overlapping each other.... They provide complete tightness. Welding is performed with special electrodes continuously rotating around their axis. The main area of ​​use is the production of devices for the conversion of electromagnetic energy.

Butt

It got its name due to the ability to perform butt-to-joint welding of small cross-section wires. Performed by reflow or resistance method... In the first case, before contact, the ends of the parts are melted under the action of an electric arc. Then they start welding. In the second case, all actions are performed at the moment of contact between the workpieces.

Advantages and disadvantages

The advantages of the devices include:

• productivity of work;
• can be used for industrial and domestic purposes;
• low power consumption;
• simple construction;
• long period of operation;
• point impact allows you to make connections without thermal deformation of the product;
• no consumables are required;
• small size allows you to freely move the device yourself.

Capacitors in welding machines operating in other technologies also play an important role. For example, aluminum electrolytic capacitors in inverters and semi-automatic devices are responsible for increasing the voltage level, and also smooth out possible ripples.

There are only two disadvantages:

1. Low power does not allow joining large-section workpieces.
2. Operation of the machine causes interference that interferes with the functioning of the working network.

With your own hands: a diagram of the simplest device

In addition to industrial work, spot welding is often used in everyday life.... Factory-made apparatus is quite expensive. On the Internet, you can find many drawings for self-assembly different directions activities. For example, do-it-yourself capacitor welding for a battery is made from a dipole coil and a transformer with contact triodes.

Consider a diagram and description of do-it-yourself capacitor welding, in which a transformer is used to transmit pulses.

The device diagram is as follows:

For assembly you will need:

1. Capacitor with a capacity of 1000 μF. To accumulate charge.
2. Ferrite core with W-shaped plates for making a transformer.
3. Copper wire with a cross section of 0.8 mm. For the primary winding, 3 turns will be enough.
4. Copper bus. It will be used to make a secondary winding, which should have 10 turns.
5. Thyristor type KU-202M. For voltage switching control.

Such a device will easily cope with elements up to 0.5 mm thick.

Diagram and description of a more powerful device

The diagram of a device for spot welding on capacitors, capable of working with products of greater thickness, is as follows:

The basis of the device is made up of 6 10,000 uF capacitors, connected into a single battery... In this case, two 70TPS12 thyristors connected in parallel were used as switches. The capacitors are charged using a boost converter. The resistance of the resistor is 130 ohms.

For visual control of the charge level, there is a 3-bar indicator light block.

The rated current is 2000 A and the voltage is 32 V.

The only drawback of this model is the charging duration of the capacitors, which is 45 seconds.

The assembled device will not be able to weld a large-diameter hairpin, but it will quite cope with a wire with a cross-section of up to 5 mm.

Please note that industrial designs are made in compliance with GOSTs governing this industry. In the case of independent inventions, all responsibility for the possible consequences lies with the designer.

Contact block device

The mechanism for fixing and moving the electrodes along the working plane is called a contact block... The primitive design involves manual contact adjustment. In advanced models, a block of hardware is responsible for the reliability of fastening.

In this case, the lower rod is fixed in a fixed position. Its length should be in the range of 10-20 mm, and its cross-section should be at least 8 mm.

The second rod is attached to the movable platform. The simplest screws are installed to adjust the pressure.

To ensure safety, there should be reliable insulation between the site and the base of the power unit.

The order of work

The workflow can be roughly divided into three stages:

1. Training... The working surface must be thoroughly cleaned from corrosion and oil stains.
2. Work cycle... Products are joined in the desired position. After that, electrodes are brought to them. The charge is supplied after pressing the start button.
3. Changing the position of a part... If necessary, the product is moved for a new point effect.

Application of ready-made devices

There are many applications for capacitor welding machines:

1. Automotive... The body elements are connected only by means of spot welding.
2. Aircraft construction... This industry is distinguished by special requirements for the accuracy of work.
3. Instrumentation... For connecting miniature elements that should not be deformed.
4. Building... This technology is used to connect thin sheet metals.
5. Homework... Devices help in repair household appliances.

Conclusion

The capacitor welder is an excellent device capable of joining products with different structures. Its main advantages are simplicity and reliability with small dimensions. If necessary, you can make a simple apparatus for household needs.

Electrical engineer of the 1st category Kalyazin Artem Vitalievich, work experience - 15 years: « At home, I do self-repair of all household appliances, with rare exceptions. Just a week ago, I got hold of a dead lithium-ion battery from a phone. With the help of materials at hand, I decided to make a small welding machine on capacitors. Exactly 6 hours passed from drawing up the scheme to the completion of the work. Efficiency pleased - wires with a cross section of 3 mm can be easily connected. Thyristors and capacitors were at hand, but if I had to buy everything in the store, then the costs did not exceed 500-600 rubles».

How is capacitor welding done by hand? Diy capacitor welding diagram and description

Diagram and description of capacitor welding

There are several ways to seamlessly join metal elements, but among all of them, capacitor welding takes a special place. The technology has become popular since about the 30s of the last century. Docking is carried out by supplying an electric current to the desired location. A short circuit is created that allows the metal to be melted.

Advantages and disadvantages of technology

The most interesting thing is that capacitor welding can be used not only in industrial conditions, but also in everyday life. It involves the use of a small-sized apparatus that has a constant voltage charge. Such a device can easily move around the working area.

Of the advantages of the technology, it should be noted:

• high productivity of work;
• the durability of the equipment used;
• the ability to connect various metals;
• low heat dissipation;
• lack of additional consumables;
• the accuracy of the connection of elements.

However, there are situations when it is impossible to use a capacitor welding machine to join parts. This is primarily due to the short duration of the power of the process itself and the limitation in the cross section of the combined elements. In addition, the impulse load is capable of creating various disturbances in the network.

Features and specificity of application

The process of joining workpieces itself involves contact welding, for the implementation of which a certain amount of energy is consumed in special capacitors. Its release occurs almost instantly (within 1 - 3 ms), due to which the heat-affected zone is reduced.

It is quite convenient to carry out capacitor welding with your own hands, since the process is economical. The device used can be connected to a conventional electrical network... For industrial use, there are special high-power devices.

The technology has gained particular popularity in workshops designed for body repair. Vehicle... When carrying out work, thin sheets of metal are not burned through and are not subject to deformation. There is no need for additional straightening.

Basic process requirements

In order for capacitor welding to be performed at a high quality level, certain conditions must be adhered to.

1. The pressure of the contact elements on the workpiece directly at the moment of the impulse must be sufficient to ensure a reliable connection. The unclenching of the electrodes should be done with a short delay, thereby achieving better regime crystallization of metal parts.
2. The surface of the workpieces to be joined must be free of contamination so that oxide films and rust do not cause too much resistance when an electric current is applied directly to the part. In the presence of foreign particles, the efficiency of the technology is significantly reduced.
3. Copper rods are required as electrodes. The diameter of the point in the contact zone should be at least 2-3 times the thickness of the element to be welded.

Technological techniques

There are three options for influencing workpieces:

1. Capacitor spot welding is mainly used to join parts with different thickness ratios. It is successfully used in the field of electronics and instrumentation.
2. Roller welding is a certain amount of point connections made in the form of a continuous seam. The electrodes resemble spinning coils.
3. Impact capacitor welding allows you to create butt joints of elements with a small section. Before the collision of the workpieces, an arc discharge is formed, melting the ends. After the contact of the parts, welding is carried out.

As for the classification according to the equipment used, then the technology can be divided according to the presence of a transformer. In its absence, the design of the main device is simplified, and the bulk of the heat is released in the area of ​​direct contact. The main advantage of transformer welding is the ability to provide a large amount of energy.

Diy capacitor spot welding: diagram of the simplest device

To connect thin sheets up to 0.5 mm or small parts, you can use a simple structure made in a domestic environment. In it, the impulse is fed through a transformer. One of the ends of the secondary winding is supplied to the array of the main part, and the other to the electrode.

In the manufacture of such a device, a circuit can be used in which the primary winding is connected to the electrical network. One of its ends is output through the diagonal of the converter in the form of a diode bridge. On the other hand, a signal is supplied directly from the thyristor, which is controlled by the start button.

The impulse in this case is generated using a capacitor with a capacity of 1000 - 2000 μF. For the manufacture of the transformer, a core Ш-40, having a thickness of 70 mm, can be taken. The primary winding of three hundred turns is easy to make from a wire with a cross section of 0.8 mm marked with PEV. A thyristor with the designation KU200 or PTL-50 is suitable for control. The secondary winding with ten turns can be made of copper bus.

More powerful capacitor welding: diagram and description of a homemade device

To increase the power indicators, it will be necessary to change the design of the manufactured device. With the right approach, it can be used to connect wires with a cross section of up to 5 mm, as well as thin sheets with a thickness of no more than 1 mm. To control the signal, a contactless starter with the MTT4K marking is used, designed for an electric current of 80 A.

Typically, the control unit includes thyristors connected in parallel, diodes and a resistor. The response interval is adjusted using a relay located in the main circuit of the input transformer.

Energy is heated in electrolytic capacitors, combined into a single battery by means of parallel connection. In the table you can see the required parameters and the number of elements.

The main transformer winding is made of a wire with a cross section of 1.5 mm, and the secondary one is made of a copper bus.

The homemade device works according to the following scheme. When the start button is pressed, the installed relay is triggered, which, using the thyristor contacts, turns on the transformer of the welding unit. Disconnection occurs immediately after the capacitors are discharged. The setting of the impulse effect is made by means of a variable resistor.

Contact block device

The manufactured device for capacitor welding should have a convenient welding module, which makes it possible to fix and freely move the electrodes. The simplest design involves hand holding the contact elements. In a more complex version, the lower electrode is fixed in a stationary position.

For this, on a suitable base, it is fixed with a length of 10 to 20 mm and a cross-section of more than 8 mm. The top of the contact is rounded. The second electrode is attached to a platform that can move. In any case, the adjusting screws must be installed, with the help of which additional pressing will be carried out to create additional pressure.

It is imperative to isolate the base from the moving platform to the contact of the electrodes.

The order of work

Before the do-it-yourself spot capacitor welding is done, you need to familiarize yourself with the main steps.

1. At the initial stage, the connected elements are properly prepared. Impurities in the form of dust particles, rust and other substances are removed from their surface. The presence of foreign inclusions will not allow achieving high-quality joining of workpieces.
2. The parts are connected to each other in the required position. They should be located between two electrodes. After squeezing, an impulse is applied to the contact elements by pressing the start button.
3. When the electrical effect on the workpiece stops, the electrodes can be moved apart. The finished part is removed. If necessary, it is installed at a different point. The size of the gap is directly influenced by the thickness of the welded element.

Application of ready-made devices

The work can be carried out using special equipment. Such a kit usually includes:

• apparatus for creating an impulse;
• fixture for welding and clamping fasteners;
• return cable equipped with two clamps;
• collet set;
• instructions for use;
• wires for connecting to the mains.

Final part

The described technology of joining metal elements allows not only welding steel products. With its help, it is possible to join parts made of non-ferrous metals without much difficulty. However, when performing welding work, it is necessary to take into account all the features of the materials used.

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DIY capacitor welding - diagram and description

April 8, 2017

This type of welding refers to the spot method. It is convenient when you need to weld small parts to each other, and one small one. Mostly capacitor welding is used for working with non-ferrous metals.

As soon as it became possible to carry out chiseled welding at home, the method began to gain popularity among inexperienced welders. This situation has added relevance to the issue today. What is this process and how to make welding with your own hands for home use? We will try to analyze this question in detail today.

What is the difference between the capacitor method and other types?

The first difference that catches your eye is the welding speed and its environmental friendliness. A standard capacitor welder operates at high voltage. This allows you to save energy, get a high-quality and even seam. Its main application lies in microwelding or, if necessary, to weld large sections. This happens with the following principle:

1. Capacitors collect the required amount of energy;
2. The charge is converted into heat, which is used for welding.

As mentioned earlier, this type of welding is environmentally friendly. The devices do not require liquid for cooling due to the absence of heat emission. This advantage allows you to add time to the life of the capacitor device.

The principle of operation of capacitor welding

In the process of spot welding, the parts are clamped by two electrodes, to which a short-term current flows. Then an arc is formed between the electrodes, and it heats the metal, melting it. The welding pulse comes into operation within 0.1 seconds, it provides a common core of melt for both parts of the workpiece being welded. When the impulse is removed, the parts continue to compress under the pressure of the load. The result is a common weld seam.

There are secondary windings, from which the current enters the electrodes, and the primary winding has a pulse that was formed during the capacitor charge. In the capacitor, the accumulation of charge occurs in the interval between the arrival of the pulse to the two electrodes. Especially good results come when it comes to welding aluminum or copper. There is a limitation on what the thickness of the workpieces should be, it should not exceed 1.5 mm. Maybe this is a minus, but such a scheme works great when welding dissimilar materials.

Types of spot welding

There are two main types of do-it-yourself capacitor welding:

1. Transformer. In which the capacitor will discharge the energy charge on the winding of the transformer equipment. In this case, the workpieces are located in the welding field, which is connected to the secondary winding.
2. Transformerless.

Advantages

As with all other types, independent capacitor welding has a number of positive features:

1. With stable operation, it is possible to save electricity;
2. Reliability and practicality. Working speed allows spot welding to be available with air cooling;
3. Work speed;
4. The welding current is very dense;
5. Accuracy. Considering the dose of energy consumed, a reliable seam of compact thickness is formed in the contact field. This method is widely used for fine welding of non-ferrous metal;
6. Profitability. The power consumption is 20 kVA maximum. This is done using power take-off due to the stabilization of the voltage in the network.

Diy assembly diagram of the unit

The primary winding is drawn through the diode bridge (rectifier), then it is connected to the voltage source. A signal is sent from the thyristor to the bridge diagonal. The thyristor is controlled by a special trigger button. The capacitor is connected to the thyristor, more precisely to its network, to the diode bridge, then it is brought out to the winding (primary). To charge the capacitor, an auxiliary circuit with a diode bridge and a transformer is switched on.

A capacitor is used as a pulse source; its capacitance should be 1000-2000 μF. For the construction of the system, a transformer is made from a core of type Ш40, the required size is 7 cm. To make the primary winding, a wire with a diameter of 8 mm is needed, which is wound 300 times. The secondary winding assumes the use of a copper bus, 10 windings. Almost any capacitors are used for the input, the only requirement is a power of 10 V., a voltage of 15.

When the work will require the connection of blanks up to 0.5 cm, it is worth applying some adjustments to the design diagram. For more convenient control of the signal, an MTT4K series starter is used, it includes parallel thyristors, diodes and a resistor. An additional relay will allow you to correct work time.

Such a homemade capacitor welding works with the following sequence of actions:

1. Press the start button, it will start the time relay;
2. The transformer is turned on by thyristors, after the relay is turned off;
3. The resistor is used to determine the pulse width.

How does the welding process take place?

After the capacitor welding is assembled with our own hands, we are ready to start work. To begin with, it is worth preparing the parts by cleaning them from rust and other dirt. Before placing the workpieces between the electrodes, they are connected in such a position in which they need to be welded. Then the device starts up. Now you can squeeze the electrodes and wait 1-2 minutes. The charge that accumulates in the high-capacity capacitor will pass through the welded fastener and the surface of the material. As a result, it melts. When these steps are done, you can proceed to the subsequent steps and weld the rest of the metal.

Before welding at home, it is worth preparing materials such as sandpaper, grinder, knife, screwdriver, any clamp or pliers.

Conclusion

Condenser welding is very widely used both at home and in the industrial area, as we can see, it is very convenient and easy to use, plus everything has a lot of advantages. With the help of this information, you can take your knowledge to a new level and successfully apply spot welding in practice.

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DIY capacitor welding: technology and varieties

Capacitor welding is a stored energy welding method. Energy charges will accumulate in capacitors during charging from a rectifier, after which they will be transformed into heat. It will be formed in the process of current flow between the parts to be welded. That is why capacitor welding is also called resistance welding.

Items that will be needed:

• welding device;
• electrode;
• transformer;
• wire;
• capacitor.

The difference between the spot welding method from other existing ones

Capacitor welding with a capacitor discharge through the primary winding of the transformer: a-diagram of the process; b-current diagram.

The main difference between this connection method is environmental friendliness. A standard capacitor welder operates at high currents, which makes it possible to obtain excellent weld quality with low energy consumption.

The capacitor welding method, like accessories for it, is most often used in cases where it is necessary to perform microwelding or join workpieces of large sections and thicknesses. DIY spot welding is as follows:

1. Capacitors store energy in the required amount.
2. The charges are converted into heat, which is used for welding.

You should be aware that spot welding is environmentally friendly, as it has practically no effect on environment... The devices used do not require liquid for cooling, as no heat is generated from them. This significant advantage makes it possible to increase the life cycle of the entire device to obtain permanent connections.

Instead of typical cylinders, special servo drives are used in the designs, and therefore there is no need for a pneumatic connection. Built-in components allow you to build up the welding force quickly and efficiently. In this case, the electrodes will act delicately on the base.

Condenser welding has the following advantages:

• the ability to weld at high speed;
• the accuracy of the connection of elements;
• high level environmental friendliness;
• connection reliability;
• durability of welding devices.

Due to the high speed, spot welding will not deform and melt the metal. The devices act gently on various workpieces. Excellent quality indicators can be obtained with the contact or impact method of joining workpieces. For example, the shock-capacitor method is best used for joining non-ferrous metals and their alloys. As a result, the seam will turn out to be aesthetic, reliable, and the process of obtaining permanent joints will take a small amount of time.

Capacitor welding is often used in industrial environments due to its combination of performance characteristics. A technological phenomenon is formed, during which the inseparable contact of metal blanks is made due to the release of heat. At the same time, dirt, oxide films, various inclusions and bulges will be removed from the welding place by means of compression force. As a result, there will be connections between the atoms of the bonded coatings.

Energy charges will accumulate when charged from a generator or rectifier. Energy adjustment can be made by changing the voltage and charging capacity.

Existing varieties of spot welding

Sometimes a connection without transformers is used. Capacitors in this case will discharge energy to the connected base. The following charging schemes are allowed:

1. 1000 μF devices will store energy for voltages up to 1000 V by means of a step-up transformer, while the welding time will be 0.005 s. The welding current is in the range from 10 to 100 A. This method is dangerous to humans due to the high voltage.
2. 40,000-400,000 μF devices will store energy for voltages up to 60 V by means of a step-down transformer. The welding time can be up to 0.6 s. in this case, the welding current is in the range from 1000 to 2000 A.

In other cases, welding using transformers is used. In this case, the capacitor will discharge the energy charge to the primary winding of the transformer device.

Types of contact welding: a - butt welding; b - point; в - roller; 1 - welding seam; 2 - electrode; 3 - parts to be welded; 4 - movable plate with a movable part; 5 - welding transformer; 6 - fixed plate.

In this case, the parts to be connected are placed in the welding circuit, which is connected to the secondary winding of the transformer. This connection method is used as microwelding with the following parameters:

• charging voltage - 1000 V;
• welding time - 0.001 s;
• welding current - 6000 A;
• capacitance of capacitor devices - 1000 μF.

The capacitor will store energy to a specific amount when the lever is placed on the left. With the right, the heat exchangers are discharged to the primary winding of the transformer structure. The capacitor connection method in the secondary winding is induced by an electromotive force. This force determines the amperage in the welding chain.

Non-ferrous metal spot welding

Non-ferrous metals contrast with common steel. In this case, can be used different methods heat treatment. Everything will depend on the type of metal to be joined. Welding of such metals has following features:

• melting temperature;
• density;
• affinity for atmospheric gases;
• mechanical performance at low and high temperatures.

According to the totality of data, metals can be distinguished:

• heavy colored;
• active and refractory;
• lungs.

From the first group, metals can be melted by spot welding without much difficulty. For copper wires, in most cases, mechanized devices are used. They are able to provide a high quality connection and maintain the original dimensions of the workpieces.

For the processing of metals of the other two groups, devices with a high concentration of energy will be needed. Do-it-yourself welding of blanks from these groups is extremely rare, since in this case volatile harmful compounds can form.

Capacitor welding technology

The process of joining workpieces by the point method consists of several stages. First of all, the workpieces to be joined will need to be combined in the required position, placed between the electrodes of the welding device, and then pressed against each other. After that, they will need to be heated to a state of plasticity and subjected to subsequent plastic deformation. In industrial conditions, in the process of using automatic structures, the welding frequency reaches 600 points / min. In order to be able to make high-quality capacitor welding with your own hands, you will need to maintain the same speed of movement of all electrodes. It is imperative to ensure the required pressure and full contact of the workpieces being welded.

The workpieces will be heated due to the passage of the welding current in the form of a short pulse. The pulse duration depends on the welding conditions and can be from 0.01 to 0.1 s. This pulse will ensure the melting of the element in the zone of action of the electrodes and a common liquid core of the two blanks is formed. The core diameter can be from 4 to 12 mm. After the current pulse ceases to act, the workpieces will be held under pressure for some time so that the formed core can cool down and crystallize.

Heating time and pressure

The duration of heating or passage of the welding current can vary, it depends on the welding conditions and the power of the structure used. In the case of joining elements made of steels that are prone to hardening and cracking, it will be necessary to increase the heating duration. This is done in order to be able to slow down further cooling of the metal. Welding of workpieces from of stainless steel will need to be done with a minimum heating time. This is necessary in order to be able to prevent the danger of heating the outer base of the junction point to the temperature of the transformation of the structure. You should be aware that as a result, the high anti-corrosion properties of the outer layers of the metal may be violated.

The force of pressure between the electrodes must ensure a reliable connection of the workpieces at the welding point. It depends on the type of metal to be joined and the thickness of the workpieces being welded. The pressure after heating is important, since its value will provide a fine-grained structure of the metal at the junction, while the strength of the junction point will be equal to the strength of the base metal.

Features of the choice and use of electrodes

Factors on which the quality of welding depends:

1. Welding quality will depend on the correct choice of the copper electrode diameter. The diameter of the connection point must be several times greater than the thickness of the thin welded joint element.
2. Pressing the blanks at the moment of passage of the welding pulse can provide the appearance of a band for compaction near the molten core. This eliminates the need for any additional security measures at the junction.
3. In order to be able to improve the crystallization of the molten workpiece, the electrodes will need to be unclenched with a short delay after the passage of the welding pulse.
4. In order to get a high-quality and reliable weld seam, the bases to be joined will need to be prepared first. In this case, we mean cleaning the elements from rust.
5. The distance between the connection points should ensure that current shunting through the near points is reduced. For example, to connect two workpieces with a thickness of 2-5 mm, the distance between the connection points will vary from 15 to 50 mm.

Electrodes used for capacitor welding must provide strength in the range of operating temperatures, high electrical and thermal conductivity, and ease of processing. Some bronzes, which include cobalt and cadmium, meet similar requirements. Copper alloys with chromium are also suitable. You should know that in terms of heat and electrical conductivity, copper is significantly superior to bronze and alloys, but this metal is many times worse in terms of wear resistance. Therefore, an EV type alloy is best suited for such purposes, which is almost pure copper with the addition of chromium and zinc.

To reduce the wear of the electrodes, during use, they must be intensively cooled with water.

How to make a device for spot welding with your own hands?

The copper wire welding device can be easily assembled by yourself. To do this, you should purchase a 450 W transformer. The transformer is needed of a standard type, with a primary copper winding 0.75x2 mm thick and a secondary winding with a 6 mm aluminum power cable. In this case, you will also need a carbon electrode.

The copper wire welding machine operates on an alternating current of 35 to 40 A. The highest voltage point is 15 V. Multiple clamps can be used as an electrode holder. The conductor for the device being manufactured can be a carbon electrode, which is made from a trolleybus contact brush.

If you use this device carefully, it can last for several years. It is necessary to monitor the contacts, as well as to ensure that the battery is not discharged. The copper wire welding scheme does not imply the use of devices with high resources. A self-made device is able to perfectly cope with significant amounts of work.

It should be noted: welding work in this case can be automated, which is a significant advantage.

Condenser welding is a complex process, so you need to know all the nuances.

moyasvarka.ru

Do-it-yourself capacitor welding machine

The device that we will present in this article is called "capacitor welding". Very small or thin objects and parts can be joined with this welding.
It differs from standard spot welding in that the heating of the junction of the parts is carried out by the energy of the discharge of the capacitors.

There are tons of electronic fun stuff in this Chinese store.

The convenience of this type of structure is in the relative simplicity of the electrical circuit, which you can assemble with your own hands. The model shown in the video is powered by a welding transformer, the alternating current is converted by a rectifier. The voltage is 70 volts. The current flows to a capacitive resistance, which, if necessary, can be replaced with a conventional resistance equal to 10 kOhm. After resistance, the current flows to a capacitor bank with a total capacity of 30,000 Mcf. The accumulated charge on the capacitors is released through the thyristor.

After turning on the power, a light comes on, which in this case acts as a voltage indicator. When the light goes out, it means that the capacitor bank is fully charged. The welding machine is then ready for use. The discharge is switched on by pressing a button built into the holder. Such welding allows you to weld not only thin plates, but also studs of different diameters to metal surfaces. For this, it is possible to hold the pin in the holder.

izobreteniya.net

Greetings to all readers of the Volt-Index website, sometimes making certain projects on the basis of lithium batteries, many readers often criticize that lithium batteries cannot be soldered. This is of course true, but if you solder very quickly and not overheat, you can. In the input of this article, we will try to make a capacitor-type resistance welding machine.

In fact, there are a lot of options for building such devices on the Internet, but we will focus on the simplest and most reliable one. This is transformerless or impact resistance welding, so that later I do not get confused, I want to say that the transformer is in our diagram.

Still, it is designed to charge the capacitor. But there are welding machines where the capacitance of the capacitor is discharged at the welding site not directly, but through an isolation transformer.

Such devices are called transformer.

Unlike conventional resistance welding machines, in which the process takes place by heating two metals, capacitor welding does not heat up the part due to the very short welding process. This is especially good for soldering batteries.

In the S3 circuit, it is connected to ground. In the archive on the diagram, everything is fixed.

The principle of operation is as follows.

The voltage from the mains transformer is rectified by a full-wave rectifier and charges a large electrolytic capacitor. It is advisable to use a battery of parallel-connected capacitors of the same voltage and capacity.

To be honest, capacities may vary, but it is important that the capacitors have the same rated voltage.

At the time of welding, the entire capacitance of the capacitor is discharged at a certain point, to which the removable contacts are connected. Moreover, as these contacts, the parts themselves can sometimes be used, which need to be welded together.

The instantaneous discharge of the capacity of powerful capacitors causes a huge current surge, the process is very short-lived, but currents can reach tens of thousands of amperes, depending on the capacity and voltage of the capacitor bank. A short-term discharge of such a capacity leads to instantaneous melting of the metal under the electrodes.

The voltage was chosen to be about 40 volts. Such stress is completely safe for humans, although it all depends on the physiology of the individual. For some, 12 volts maximum.

But, in any case, 40 volts is not fatal. Since the device was planned to be powered from the mains, a step-down transformer must be used to charge the capacitors.

In our case, a transformer was used that produces about 30 volts on the secondary at a current of 1.5 amperes, which is great for our purposes.

After the rectifiers, the voltage across the capacitors will be about 40 volts. Naturally, due to an unstabilized source, this voltage can deviate in one direction or another, depending on the voltage in the network.

In principle, any transformer with a power of more than 50 watts is suitable, which provides the required voltage at the output. The charging time of the capacitors will depend on the secondary winding current.

To limit the capacitor charging current, a 10-watt wire-type resistor with a resistance of 10-15 ohms is used.

If you do not limit the charge current, then the system will consume colossal currents, as a result of which the diode bridge may burn out.

The device has a thyristor contactor.

When the low-current button is pressed, a powerful thyristor will work, which will discharge the entire capacity of the capacitor bank, that is, a short circuit will occur. In our case, the thyristor T 171-320 was taken.

The short-term surge current in our system can be up to 4,000 amperes.

In order for this "monster" to work, you need to apply a voltage of 3.5 - 12 volts to the control electrode. The specified voltage can be obtained by using a voltage divider based on two 0.5-1 watt resistors. By selecting them at the midpoint, you need to get the earlier indicated voltage.

A ready-made 10 Ampere bridge was used as a diode rectifier, the bridge voltage is at least 100 volts, although such bridges are made for 400 volts or more. The bridge does not heat up during operation, but it is advisable to place it on a heat sink.

The chain of a resistor, LED and zener diode is an indicator of the capacitors' charge and when they reach about 40 volts, the LED lights up, which indicates that the device is ready for use.

You can also use a digital voltmeter.

In the absence of 40 volt zener diodes, several smaller ones can be used.

You can take any LED, and the limiting resistor is 0.25 watts.

Capacitors were taken with a voltage of 50 volts - preferably 63 or 100 volts. The total battery capacity was 41,000 microfarads.

Of course, you can increase the capacitance of the capacitors if only the thyristor cope, and the increase in capacitance will make it possible to cook larger parts.

The capacitors were soldered to a common board, the tracks were additionally reinforced. Also, a 5-watt 1.5 kΩ resistor was soldered parallel to the capacitors. To discharge the latter after turning off the device. There was also a button for an emergency discharge of the container. Here the principle is the same - the discharge through the resistor only in this case it is low-resistance.

To start the thyristor, you can use absolutely any low-voltage button.

A simple dimmer can be implemented in the primary circuit of the transformer. This will allow you to adjust the voltage across the capacitors and select the optimal voltage for welding parts from certain metals.

Attached files: DOWNLOAD.

volt-index.ru

Developed in the 30s of the twentieth century, the technology of capacitor welding has become widespread. A number of factors contributed to this.

• Simplicity of the design of the welding machine. If you wish, you can assemble it yourself.
• Relatively low energy consumption of the working process and small loads created on the electrical network.
• High performance, which is undoubtedly important in the production of serial products.
• Reducing the thermal effect on the materials to be joined. This feature of the technology makes it possible to use it when welding small-sized parts, as well as on viewing surfaces, where the use of conventional methods would inevitably lead to undesirable deformations of the material.

If we add to this that for the application of high-quality joint seams it is enough to have an average skill level, the reasons for the popularity of this method of resistance welding become obvious.

The technology is based on conventional resistance welding. The difference is that the current is not supplied to the welding electrode continuously, but in the form of a short and powerful pulse. This impulse is obtained by installing large capacitors in the equipment. As a result, it is possible to achieve good performance of two important parameters.

1. Short thermal heating time of the parts to be joined. This feature is successfully used by manufacturers of electronic components. Transformerless installations are best suited for this.
2. High current power, which is much more important for the quality of the seam than its voltage. This power is obtained using transformer systems.

Varieties of technology

Depending on the production requirements, one of three technological methods is chosen.

1. Spot capacitor welding. Using a short pulse of current emitted by a capacitor, parts are connected in precision mechanical engineering, vacuum and electronic engineering. This technology is also suitable for welding parts that differ significantly in thickness.
2. The roll-over seam allows a completely sealed joint consisting of many overlapping weld points. This leads to the use of technology in the process of manufacturing electrovacuum, membrane and bellows devices.
3. Butt welding, which can be produced both by contact and non-contact methods. In both cases, melting occurs at the junction of the parts.

Application area

The fields of application of the technology are different, but with particular success it is used for fastening bushings, studs and other fasteners to sheet metal. Taking into account the peculiarities of the process, it can be adapted to the needs of many industries.

• Automotive industry, where it is necessary to reliably interconnect body panels made of sheet steel.
• Aircraft industry with special requirements for the strength of welded seams.
• Shipbuilding, where, taking into account the large volume of work, saving energy and consumables gives a particularly tangible result.
• Production of precision instruments, where significant deformations of the parts to be joined are unacceptable.
• Construction in which sheet metal structures are widespread.

Equipment that is simple to use and easy to use is in demand everywhere. With its help, you can organize the production of small-scale products or equip a personal plot.

Homemade capacitor welding

In stores, you can easily purchase ready-made equipment. But due to the simplicity of its design, as well as the low cost and availability of materials, many people prefer to assemble devices for capacitor welding with their own hands. The desire to save money is understandable, and it is easy to find the desired scheme and detailed description on the network. A similar device works as follows:

• The current is directed through the primary winding of the supply transformer and the rectifying diode bridge.
• A control signal from a thyristor equipped with a start button is applied to the diagonal of the bridge.
• A capacitor is built into the thyristor circuit, which serves to accumulate the welding pulse. This capacitor is also connected to the diagonal of the diode bridge and connected to the primary winding of the transformer coil.
• When the device is connected, the capacitor accumulates a charge, being supplied from the auxiliary network. When the button is pressed, this charge rushes through the resistor and auxiliary thyristor towards the welding electrode. The auxiliary network is then switched off.
• To recharge the capacitor, release the button by opening the resistor and thyristor circuit and reconnecting the auxiliary network.

The duration of the current pulse is regulated by a control resistor.

It's just principle description operation of the simplest equipment for capacitor welding, the device of which can be changed, depending on the tasks to be solved and the required output characteristics.

Need to know

Anyone who decides to assemble his welding machine on his own should pay attention to the following points:

• The recommended capacitance of the capacitor should be about 1000 - 2000 uF.
• For the manufacture of a transformer, a core of the Ш40 variety is best suited. Its optimum thickness is 70 mm.
• Primary winding parameters - 300 turns of copper wire with a diameter of 8 mm.
• The parameters of the secondary winding are 10 turns of a copper bus with a cross section of 20 square millimeters.
• The PTL-50 thyristor is well suited for control.
• The input voltage must be provided by a transformer with a power of at least 10 W and an output voltage of 15 V.

Based on this data, you can assemble a fully functional device for spot welding. And although it will not be as perfect and convenient as factory-made equipment, with its help it will be quite possible to master the basics of the profession of a welder and even start manufacturing various parts.

Using the described technology, it is possible to join not only thin steel sheets, but also non-ferrous metal products. When carrying out work, it is important to take into account not only the thickness, but also other features of the materials. If the metal is prone to the formation of microcracks during heating, or high internal stresses arise during its processing, it is necessary to increase the pulse duration, thus raising the heating temperature.

svarkalegko.com

Capacitor spot welding, contact and impact technology: equipment design

One of the main types of resistance welding, widely used in industry, can be called capacitor welding. The rules for its implementation are regulated by GOST.

Its principle is based on the discharge accumulated on the capacitor bank of the electric charge to the connected products. At the point of contact of the electrodes, a discharge occurs and a short electric arc is formed, sufficient to melt the metal.

Division into types

Condenser welding is most widely used in instrument making. It is capable of welding metals up to 1.5 mm, and the thickness of the second part can be much greater. In the welding of thin products in terms of efficiency, productivity and quality, capacitor welding has no competitors.

It can be transformer and transformerless. In the first variant, more energy can be stored on capacitors by using high voltage and discharging through a step-down transformer with high currents. The second option is simple and minimal in detail.

Depending on the characteristics of the seam formation, capacitor welding is subdivided into:

• point;
• suture;
• butt.

The first, point method, is mainly used in instrument making and the production of electronic equipment. It is actively used for welding thin parts with thick ones.

Seam welding, also called roller welding, is used when welding membranes and electric vacuum devices. A continuous, tight seam is obtained due to the fact that the point connections are made with overlap. Rotating rollers play the role of electrodes.

Butt welding is carried out by flash or resistance. In the first method, a discharge first occurs between the parts to be welded, the place of the future joint is melted under the action of the formed arc, and then they are deposited, after which the metals are joined. In the second case, the discharge and subsequent welding occurs at the moment of contact of the parts.

Advantages

The advantage of capacitor welding is that due to the high energy density and short duration of the welding pulse, the heat affected zone is very small, stresses and deformations are minimal. The equipment is simple and efficient.

Due to the fact that at the moment of discharge the capacitor unit is disconnected from the network, it does not affect its parameters in any way. The only drawback is that it only applies to thin metals.

Another advantage of capacitive welding is its compactness. Capacitor welding does not require powerful power sources, the device can be charged between the transfer of the electrode to the next point.

In the process of welding, there are practically no harmful gases. The device is very economical, all the stored energy is used to melt the metals at the junction point. Due to the fact that the charge on the capacitors is constant, a high-quality and stable arc is obtained.

Condenser welding allows you to weld non-ferrous metals of small thickness. In addition, it can join dissimilar metals and alloys due to its high energy concentration in a small area.

Due to the fact that the capacitor welding system operates in a discrete mode (first charge, then discharge), air cooling is enough for it, which simplifies the design of the welding unit.

Capacitive welding machine is used for joining steels of all types, parts made of brass, aluminum, bronze. It can weld dissimilar metals, thin to thick sheets.

The ability to adjust the discharge energy and pulse duration allows microwelding, for example, in a watch mechanism. The capacitor can weld refractory tungsten filaments and is used in jewelry.

Technological features

Depending on the technological process, capacitor-type welding is:

• contact;
• shock;
• point.

During resistance welding, the energy accumulated in the container is discharged onto metal parts that were previously tightly connected to each other. In the place where the electrodes are pressed, an electric arc occurs, in which the current reaches 10-15 thousand amperes with an arc duration of up to 3 ms.

In the case of shock capacitor welding, the discharge occurs at the moment of a brief impact of the electrode on the workpiece. The duration of the arc is 1.5 ms. This reduces the thermal impact on the surrounding area and improves the weld quality.

In capacitor spot welding, an arc appears between the electrodes and the workpieces between them. The discharge process lasts from 10 to 100 ms (depending on the settings), and the metals are joined in a small area.

Transformerless apparatus

Having decided to make an apparatus for capacitor welding on their own, they first choose a version. The simplest option is a transformerless circuit. It can be implemented with high or low voltage capacitors.

In the first case, you will need a step-up transformer and 1000 V capacitors with a capacity of 1000 μF. In addition, you will need a high-voltage diode bridge for AC rectification, a switch, electrodes with connecting wires.

Welding takes place in two stages. At the first stage, the container is charged, at the second, after switching its leads to the welding electrodes and touching them to the welding place, a discharge occurs, and the parts are connected. The flowing current reaches 100 A, the pulse duration is 5 ms. This option is dangerous to humans due to the high operating voltage.

The second option requires a step-down transformer, a capacitor bank for voltages up to 60 V with a capacity of 40,000 μF or more, a diode bridge, and a switch.

The welding process is identical to the first case, only currents of 1-2 kA and a duration of up to 600 ms pass through the welding point. The power of the transformer does not really matter, it can be 100-500 W.

DIY transformer circuit

When using a transformer circuit, you will need a step-up transformer and a diode bridge for charging at 1 kV, 1000 μF capacitors and a step-down transformer, through the secondary winding of which the accumulated charge is discharged at the junction of the workpieces.

With this design of the spot welding machine, the discharge duration is 1 ms, and the current reaches 6000 A. After charging the capacitor bank with a switch, they are connected to the primary winding of the step-down transformer. An EMF is induced in the secondary winding, which causes huge currents with closed electrodes on the workpieces to be connected.

The quality of welding will also greatly depend on the condition of the electrode block. The simplest option is the clamps for fixing and pressing the contactors.

But the design is more reliable, where the lower electrode is stationary, and the upper one can be pressed against the lower one with the help of a lever. It is a copper rod with a diameter of 8 mm and a length of 10-20 mm fixed to any base.

The upper part of the bar is rounded to obtain reliable contact with the metal being welded. A similar copper rod is installed on a lever, when lowering which, the electrodes should be tightly connected. The base with the lower electrode is insulated from the upper arm. The secondary winding is connected to the electrodes with a 20 mm2 wire.

The primary winding is wound with PEV-2 0.8 mm, the number of turns is 300. The secondary winding of ten turns is wound with a 20 mm2 wire. A core Ш 40 70 mm thick can be used as a magnetic circuit. To control the charge / discharge, a PTL-50 or KU202 thyristor is used.

Preparation of parts

Before starting capacitor welding, it is necessary to prepare the parts to be connected. Rust, scale and other contaminants are cleaned from them.

The workpieces are aligned properly and then placed between the lower fixed electrode and the upper movable one. Then they are strongly compressed by the electrodes. By pressing the start button, an electric discharge is supplied.

At the point of contact of the electrodes, metal is welded. It is necessary to unclench the electrodes after a while, necessary for the cooling and crystallization of the welding place under pressure.

After that, the part moves, during this time the device has time to charge, and the welding process is repeated. The size of the weld should be 2-3 times larger than the smallest thickness of the workpieces to be joined.

When it is necessary to weld a sheet up to 0.5 mm thick to other parts, regardless of their thickness, a simplified welding method can be applied. One electrode is clamped to the thick work piece to be welded at any convenient place.

In the place where you need to weld a thin part, it is pressed manually by the second electrode. Car clips can be used. Then welding is done. As you can see, the process is not too complicated, and affordable for home conditions.

There are many welding technologies for different materials, including capacitor welding. The technology has been known since the 30s of the last century and represents a variety. The connection of metals occurs during melting in places of short circuit of an electric current due to the applied discharge energy of charged high-capacity capacitors. The process takes 1-3 milliseconds.

The basis of the apparatus is a capacitor or a block of capacitors, which are charged by a constant voltage power supply. After reaching the required energy level during the charging process, the electrodes of the capacitors are connected to the welding points. The current flowing during the discharge between the parts to be welded causes the surfaces to heat up to such an extent that the metal melts and forms a high-quality one.

Despite a number of advantages, capacitor welding has a number of limitations that do not allow its use everywhere. Among them:

pros	Minuses
high process speed on automated production, up to 600 points per minute	short-term power of the welding process
precise joining of parts and repeatability of processes on the line	restrictions on the dimensions of the section of the parts to be welded
does not transmit infrared and ultraviolet radiation	impulse load creates network disturbances and high short-term loads
equipment durability
welding of different metals
low heat generation, no need for coolant
no consumables such as electrodes or welding wire

Despite some disadvantages, the method of joining metals is widely used in industry and in everyday life.

Types of welding capacitor machines

There are two types of capacitor welding machines - with the discharge of energy storage directly on the surfaces to be welded and with a discharge from the secondary winding of the transformer. The first, transformerless method, is more often used in shock-capacitor welding. The second method, transformer, is used to create a high-quality seam.

Shock-capacitor equipment welds parts during the impact of one of the electrodes on the part. During the impact, the surface parts are tightly pressed against each other. The capacitor discharges, forming a micro-arc, which heats the surfaces to the melting point of the metals. Details are firmly connected.

In the transformer welding method, the capacitor, after being charged, is connected to the primary winding of the step-down transformer. A potential appears on the secondary winding that is several times smaller than the amplitude of the incoming pulse. During the discharge, the parts are welded, the capacitor is charged again and again gives off energy to the primary winding of the transformer. This allows long bursts of up to 5 shocks per second to be produced, which create strong and precise welds.

Specificity of application

Condenser welding is an economical process, so it is convenient to use it at home with a low-power single-phase network. The industry produces household welders with a power of 100-400 watts, which are intended for home use or in small private workshops.

Capacitor welding is especially popular in car body repair shops. Unlike arc welding, capacitor welding does not burn or deform the thin walls of the sheets of body parts. There is no need for additional straightening.

Also, capacitor welding is used in electronics for welding products that are not soldered using conventional fluxes or fail from overheating.

Capacitor welding machines are used by jewelers to make or repair jewelry.

In industry, the point connection is used for:

• welding bolts, hooks, nuts, studs and other hardware to surfaces;
• connections between different metals, including non-ferrous ones;
• welding of watch parts, photo and film equipment;
• manufacture of optical and light devices;
• assemblies of electronic equipment
• and etc.

Capacitor welding is used to join microscopic parts that cannot be arc welded.

DIY condenser apparatus

The capacitor-type welding machine can be made independently and used for domestic purposes. This will require

• transformer for 220 volts with a power of 5-20 W with an output voltage of 5V;
• four rectifier diodes with a direct current of at least 300mA (for example, D226b);
• thyristor PTL-50, modern replacement T142-80-16, KU 202 or similar;
• electrolytic capacitor 1000.0 x25 V;
• variable resistor 100 Ohm;
• a transformer with a power of at least 1000 W (suitable for microwaves);
• electrodes or a welding gun (different designs are described on the Internet many times);
• copper wire with a cross section of at least 35 mm sq. - 1 meter.
• switches, fuses, case at discretion.

If the installation is made according to the scheme without errors and the parts are in good order, then there will be no problems with the device's performance.

The only problem is the output transformer. If you really decide to use a microwave transformer, and you can buy it cheaply in the used parts markets, then get ready that it needs to be redone.

It is necessary to remove the magnetic shunts and the secondary winding and wind 2-5 turns of the secondary winding around the vacant place with a thick copper wire... The number of turns may need to be changed during the tuning process. It is considered optimal that the output voltage should fluctuate within 2-7 volts, but this value also depends on the duration of the welding pulse, the thickness of the materials to be welded. There is no need to be afraid to experiment, choosing different modes with a variable resistor and changing the number of turns. But do not try to get the apparatus to do what a normal arc process can do. It will not work to cook water pipes and fittings, this device is for other purposes.

The devices for the transformerless type are not much more complicated, but they are more cumbersome. A set of capacitors with a total capacity of about 100,000 microfarads will be required. This is a decent size and weight battery. It can be replaced with a compact supercapacitor, but the device is not cheap. In addition, electrolytic capacitors are not durable. Therefore, portable and household capacitor spot welders are usually manufactured according to a transformer scheme.

Modern devices are manufactured using slightly different technologies. The frequency and power of the discharge is regulated by PIC-controllers, it is possible to automate processes, control through a computer or monitor interface. But the physical processes of welding have not changed. Once you have assembled the simplest unit, you can subsequently add elements of computer control, production automation and control to it.

If this topic is close to you and you are ready to supplement it or challenge it, share your opinion, tell us, post descriptions of your decisions in the comment block.

• Spot welding principle
• Capacitor Welding Requirements
• Simple design for spot welding
• Apparatus with increased power
• Contact block designs
• Condenser spot welding

Often there is a need for spot welding, when you do not need to connect pipes or profiles, but you just need to attach a small but important part. Do-it-yourself capacitor welding will help to accomplish this.

Resistance welding is a fairly popular type of joining metals, especially non-ferrous ones. Many people strive to be able to do it at home. DIY capacitor welding is quite affordable and easy to do.

Varieties of capacitor welding

Capacitor welding is a type of welding in which the metal is melted due to the stored electrical energy in the capacitors. According to the method of carrying out, capacitor welding can be divided into contact, impact and spot welding.

Resistance welding implies that the capacitor is discharged onto two metal workpieces previously pressed against each other. At the point of contact, an arc arises, which melts and joins the workpieces in a small area of ​​their contact. The welding current in the arc zone reaches 15 kA with an exposure time of up to 3 ms. In impact welding, the contact between metal workpieces, to which the discharge is applied, occurs in the form of a short-term impact. In this case, the duration of the arc does not exceed 1.5 ms, which further reduces the welding area.

In spot welding, the discharge is applied to two copper electrodes, which at points touch the surface of the metals on both sides. The arc is formed between the electrodes for 0.01-0.1 s depending on the setting. The welding current can reach 10 kA. Metal welding takes place almost at a point.

Capacitor welding circuit.

By the type of discharge formed, capacitor welding is subdivided into transformerless and transformer welding. In the first type, the discharge from the capacitors goes directly to the metal surface. Such welding can be carried out by means of a high-voltage discharge (voltage up to 1 kV) with a current of up to 100 A for 0.005 s or a low-voltage discharge (voltage up to 60 V) with a current of 1-2 kA for up to 0.6 s.

The transformer type of capacitor welding consists in the fact that the discharge from the capacitor is carried out to the transformer winding, and from its secondary winding it enters the welding zone. This type of welding expands the process control possibilities. The discharge voltage reaches 1 kV, while a welding current of up to 6 kA is achieved in the secondary winding, which is applied for up to 0.001 s.

Back to the table of contents

The most common type of capacitor welding in the home is transformer spot welding. The basic principle of spot welding is that the workpieces to be welded, aligned in the required position, are clamped between two electrodes, which are supplied with a short-time welding current of a large value. An electric arc formed between the electrodes melts the metal of the workpieces in a zone with a diameter of 4-12 mm, which leads to their joining.

The action of the welding pulse is provided for 0.01-0.1 s, which ensures the formation of a melt core common for both metals being welded. After removing the current pulse, a compressive load continues to act on the workpieces, which ensures the formation of a common weld. The limitation of the zone of melting of metals is achieved by the fact that at the moment of the impulse, the metals were in contact with each other, providing heat removal.

The welding current (pulse) is supplied to the electrodes from the secondary winding, where a large current is provided at a low voltage. A pulse is applied to the primary winding that occurs when the capacitor (or capacitor bank) is discharged. In the capacitor itself, the charge accumulates in the period between the application of pulses to the electrodes, i.e. the capacitor is charged while the electrodes move to another point for welding.

The scope of such welding is extensive in terms of the type of material. Particularly good results are obtained when welding non-ferrous metals, including copper and aluminum. There is a significant limitation on the thickness of the sheets to be welded - up to 1.5 mm. But spot welding has proven itself perfectly in the case of attaching thin strips of wire to any massive structure. In this case, the materials to be joined can be dissimilar.

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In order for capacitor spot welding with your own hands to be done efficiently, certain conditions must be met. The supply of a short-term impulse for up to 0.1 s and the subsequent accumulation of energy from the network for a new impulse in a very short time must be ensured.

The pressure of the electrodes on the parts to be welded at the moment the welding pulse is applied must ensure reliable contact between them. The expansion of the electrodes must be carried out with a delay in order for the melt to cool under pressure, which improves the mode of solidification of the metal in the weld.

Copper electrodes are the most common electrodes for spot welding. The diameter of the point at the point of contact should be 2-3 times the thickness of the thinnest workpiece to be welded.

The surface of the workpieces to be welded must be thoroughly cleaned before welding so that oxide films and rust do not create high resistance to current.

Do-it-yourself capacitor spot welding can only be done if a device is assembled that has at least two units: a welding pulse source and a welding unit. In addition, it is necessary to provide for the possibility of regulating the welding mode and protection.

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When welding thin sheets (up to 0.5 mm) or when welding thin elements to any parts, a simplified design of the welding machine can be used. In it, the welding pulse is supplied through a transformer. In this case, one end of the secondary winding is connected directly to a massive part, to which a thin part is welded, and the other end is connected to an electrode. In other words, the device provides for the use of only one (upper) electrode. Pressing it to a thin part is done manually. You can, for example, use standard car battery clips (alligator clip) to attach and hold the electrode.

When making a simple welding current (pulse) source, you can use the following scheme. The primary winding of the transformer feeding the welding unit is connected to the mains, with one end through one of the diagonals of the rectifier diode bridge. The other diagonal of this bridge is supplied with a signal from the thyristor, which is controlled by the start button.

The welding pulse is accumulated in a capacitor, which is located in the thyristor circuit and is connected to the diagonal of the bridge with an output to the primary winding of the transformer. The capacitor is charged from an auxiliary circuit that includes an input transformer and a rectifier diode bridge.

The source works in the following order. While the welding transformer is disconnected, the capacitor is being charged from the auxiliary network. When the start button is pressed (turning on the welding transformer), the capacitor is disconnected from the auxiliary network and discharged to the primary winding of the transformer through a resistor. The discharge of the capacitor flows through the control thyristor. The duration of the discharge is changed by means of a regulating resistor. When the button is turned off, the discharge circuit is broken, and the auxiliary circuit is turned on, the capacitor charging cycle begins.

The source of the pulse is a 1000 μF or 2000 μF capacitor for voltages up to 25 V. An important element of the circuit is a transformer. It can be made on the basis of a Ø 40 core with a thickness of 70 mm. The primary winding is made of PEV-2 wire with a diameter of 0.8 mm. The number of turns is 300. The secondary winding has 10 turns and is made of a copper bus with a cross section of 20 mm². For control, you can use a PTL-50 or KU202 thyristor. As an input transformer, you can use any 10 W transformer with a secondary voltage of 15 V. Using the recommended source, you can provide a current pulse of up to 500 A with a duration of up to 0.1 s.

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Seam welding diagram.

To increase the power of the welding power source, a design change should be recommended that allows welding sheets up to 1 mm thick or wires up to 5 mm thick. The signal is controlled using an MTT4K contactless starter for a current of 80 A and a reverse voltage of up to 800 V. The control module includes two parallel-connected thyristors, two diodes and a resistor. The response time is regulated by a time relay included in the input transformer circuit.

Energy accumulation takes place in electrolytic capacitors collected in a battery by parallel connection... Capacitors, usually in the amount of 6 pieces, are selected of the following rating: two capacitors with a capacity of 47 μF, two with a capacity of 100 μF, two with a capacity of 470 μF, for an operating voltage of at least 50 V. voltage up to 20 V.

Relief welding scheme.

The primary winding of the welding transformer is made of a wire with a diameter of 1.5 mm, and the secondary winding is made of a copper bus or wire with a cross section of at least 60 sq. Mm. The number of turns in the secondary winding is 4-7. This provides a current in the welding zone up to 1500 A.

The device works as follows. When the start button is pressed, a relay is triggered, which, through the control contacts of the thyristors, turns on the welding transformer. After the capacitors are discharged, the relay is disconnected. The exact regulation of the pulse duration is carried out by a variable resistor.

Due to the increase in power, the welding unit should be made more reliable. It uses two copper electrodes. Quite often, welding pliers are used as electrodes, in which a pressure of up to 20 kg / cm² is provided. The diameter of the contact pads is chosen to be the smallest.

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The welding block is a contact block, i.e. a device that allows you to attach and move the electrodes. The simplest design involves manually holding and squeezing the electrodes. A more reliable system provides a stationary lower electrode and a movable upper electrode. In this case, a copper rod of small length (10-20 mm) with a diameter of at least 8 mm is fixed on any base. The upper edge of the electrode is rounded. The upper electrode from the same rod is fixed on the platform, which has the ability to move freely upward or recline. Adjusting screws should be provided to create additional pressure after the upper electrode contacts the workpiece surface. The base of the block and the top platform must be reliably insulated from each other until the electrodes contact.

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The whole process of do-it-yourself capacitor spot welding can be divided into several stages. First, the surface of the workpieces to be welded is prepared. Then the workpieces are aligned in the required order, placed in the space between the electrodes and squeezed by them. A welding pulse is sent using the start button. In 1-2 minutes after the termination of the pulse, the electrodes move apart. The welded part is removed and installed at a different point.

The spacing between weld points depends on the thickness of the workpiece and usually ranges from 15-60 mm.

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The welding process is repeated.

To do spot welding with your own hands, you will need the following additional tool:

• vice;
• hacksaw;
• Bulgarian;
• emery circle;
• file;
• pliers;
• screwdriver;
• wrenches;
• emery cloth;
• tester;
• a hammer;
• chisel;
• calipers.

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Do-it-yourself capacitor welding will help you connect thin sheets of any metal or weld small ones to any metal structure. Such spot welding is quite simple and affordable.

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Diagram and description of capacitor welding

There are several ways to seamlessly join metal elements, but among all of them, capacitor welding takes a special place. The technology has become popular since about the 30s of the last century. Docking is carried out by supplying an electric current to the desired location. A short circuit is created that allows the metal to be melted.

Advantages and disadvantages of technology

The most interesting thing is that capacitor welding can be used not only in industrial conditions, but also in everyday life. It involves the use of a small-sized apparatus that has a constant voltage charge. Such a device can easily move around the working area.

Of the advantages of the technology, it should be noted:

• high productivity of work;
• the durability of the equipment used;
• the ability to connect various metals;
• low heat dissipation;
• lack of additional consumables;
• the accuracy of the connection of elements.

However, there are situations when it is impossible to use a capacitor welding machine to join parts. This is primarily due to the short duration of the power of the process itself and the limitation in the cross section of the combined elements. In addition, the impulse load is capable of creating various disturbances in the network.

Features and specificity of application

The process of joining workpieces itself involves contact welding, for the implementation of which a certain amount of energy is consumed in special capacitors. Its release occurs almost instantly (within 1 - 3 ms), due to which the heat-affected zone is reduced.

It is quite convenient to carry out capacitor welding with your own hands, since the process is economical. The applied device can be connected to a regular electrical network. For industrial use, there are special high-power devices.

The technology has gained particular popularity in workshops designed for the repair of vehicle bodies. When carrying out work, thin sheets of metal are not burned through and are not subject to deformation. There is no need for additional straightening.

Basic process requirements

In order for capacitor welding to be performed at a high quality level, certain conditions must be adhered to.

1. The pressure of the contact elements on the workpiece directly at the moment of the impulse must be sufficient to ensure a reliable connection. Unclenching of the electrodes should be done with a short delay, thereby achieving the best mode of crystallization of metal parts.
2. The surface of the workpieces to be joined must be free of contamination so that oxide films and rust do not cause too much resistance when an electric current is applied directly to the part. In the presence of foreign particles, the efficiency of the technology is significantly reduced.
3. Copper rods are required as electrodes. The diameter of the point in the contact zone should be at least 2-3 times the thickness of the element to be welded.

Technological techniques

There are three options for influencing workpieces:

1. Capacitor spot welding is mainly used to join parts with different thickness ratios. It is successfully used in the field of electronics and instrumentation.
2. Roll welding is a certain number of spot joints made in the form of a continuous seam. The electrodes resemble spinning coils.
3. Impact capacitor welding allows you to create butt joints of elements with a small section. Before the collision of the workpieces, an arc discharge is formed, melting the ends. After the contact of the parts, welding is carried out.

As for the classification according to the equipment used, then the technology can be divided according to the presence of a transformer. In its absence, the design of the main device is simplified, and the bulk of the heat is released in the area of ​​direct contact. The main advantage of transformer welding is the ability to provide a large amount of energy.

Diy capacitor spot welding: diagram of the simplest device

To connect thin sheets up to 0.5 mm or small parts, you can use a simple structure made in a domestic environment. In it, the impulse is fed through a transformer. One of the ends of the secondary winding is supplied to the array of the main part, and the other to the electrode.

In the manufacture of such a device, a circuit can be used in which the primary winding is connected to the electrical network. One of its ends is output through the diagonal of the converter in the form of a diode bridge. On the other hand, a signal is supplied directly from the thyristor, which is controlled by the start button.

The impulse in this case is generated using a capacitor with a capacity of 1000 - 2000 μF. For the manufacture of the transformer, a core Ш-40, having a thickness of 70 mm, can be taken. The primary winding of three hundred turns is easy to make from a wire with a cross section of 0.8 mm marked with PEV. A thyristor with the designation KU200 or PTL-50 is suitable for control. The secondary winding with ten turns can be made of copper bus.

More powerful capacitor welding: diagram and description of a homemade device

To increase the power indicators, it will be necessary to change the design of the manufactured device. With the right approach, it can be used to connect wires with a cross section of up to 5 mm, as well as thin sheets with a thickness of no more than 1 mm. To control the signal, a contactless starter with the MTT4K marking is used, designed for an electric current of 80 A.

Typically, the control unit includes thyristors connected in parallel, diodes and a resistor. The response interval is adjusted using a relay located in the main circuit of the input transformer.

Energy is heated in electrolytic capacitors, combined into a single battery by means of parallel connection. In the table you can see the required parameters and the number of elements.

The main transformer winding is made of a wire with a cross section of 1.5 mm, and the secondary one is made of a copper bus.

The homemade device works according to the following scheme. When the start button is pressed, the installed relay is triggered, which, using the thyristor contacts, turns on the transformer of the welding unit. Disconnection occurs immediately after the capacitors are discharged. The setting of the impulse effect is made by means of a variable resistor.

Contact block device

The manufactured device for capacitor welding should have a convenient welding module, which makes it possible to fix and freely move the electrodes. The simplest design involves hand holding the contact elements. In a more complex version, the lower electrode is fixed in a stationary position.

For this, on a suitable base, it is fixed with a length of 10 to 20 mm and a cross-section of more than 8 mm. The top of the contact is rounded. The second electrode is attached to a platform that can move. In any case, the adjusting screws must be installed, with the help of which additional pressing will be carried out to create additional pressure.

It is imperative to isolate the base from the moving platform to the contact of the electrodes.

The order of work

Before the do-it-yourself spot capacitor welding is done, you need to familiarize yourself with the main steps.

1. At the initial stage, the connected elements are properly prepared. Impurities in the form of dust particles, rust and other substances are removed from their surface. The presence of foreign inclusions will not allow achieving high-quality joining of workpieces.
2. The parts are connected to each other in the required position. They should be located between two electrodes. After squeezing, an impulse is applied to the contact elements by pressing the start button.
3. When the electrical effect on the workpiece stops, the electrodes can be moved apart. The finished part is removed. If necessary, it is installed at a different point. The size of the gap is directly influenced by the thickness of the welded element.

Application of ready-made devices

The work can be carried out using special equipment. Such a kit usually includes:

• apparatus for creating an impulse;
• fixture for welding and clamping fasteners;
• return cable equipped with two clamps;
• collet set;
• instructions for use;
• wires for connecting to the mains.

Final part

The described technology of joining metal elements allows not only welding steel products. With its help, it is possible to join parts made of non-ferrous metals without much difficulty. However, when performing welding work, it is necessary to take into account all the features of the materials used.

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Do-it-yourself capacitor welding

This type of welding refers to the spot method. It is convenient when you need to weld small parts to each other, and one small one. Mostly capacitor welding is used for working with non-ferrous metals.

As soon as it became possible to carry out chiseled welding at home, the method began to gain popularity among inexperienced welders. This situation has added relevance to the issue today. What is this process and how to make welding with your own hands for home use? We will try to analyze this question in detail today.

What is the difference between the capacitor method and other types?

The first difference that catches your eye is the welding speed and its environmental friendliness. A standard capacitor welder operates at high voltage. This allows you to save energy, get a high-quality and even seam. Its main application lies in microwelding or, if necessary, to weld large sections. This happens with the following principle:

1. Capacitors collect the required amount of energy;
2. The charge is converted into heat, which is used for welding.

The principle of operation of capacitor welding

In the process of spot welding, the parts are clamped by two electrodes, to which a short-term current flows. Then an arc is formed between the electrodes, and it heats the metal, melting it. The welding pulse comes into operation within 0.1 seconds, it provides a common core of melt for both parts of the workpiece being welded. When the impulse is removed, the parts continue to compress under the pressure of the load. The result is a common weld seam.

There are secondary windings, from which the current enters the electrodes, and the primary winding has a pulse that was formed during the capacitor charge. In the capacitor, the accumulation of charge occurs in the interval between the arrival of the pulse to the two electrodes. Especially good results come when it comes to welding aluminum or copper. There is a limitation on what the thickness of the workpieces should be, it should not exceed 1.5 mm. Maybe this is a minus, but such a scheme works great when welding dissimilar materials.

Types of spot welding

There are two main types of do-it-yourself capacitor welding:

1. Transformer. In which the capacitor will discharge the energy charge on the winding of the transformer equipment. In this case, the workpieces are located in the welding field, which is connected to the secondary winding.
2. Transformerless.

Advantages

As with all other types, independent capacitor welding has a number of positive features:

1. With stable operation, it is possible to save electricity;
2. Reliability and practicality. Working speed allows spot welding to be available with air cooling;
3. Work speed;
4. The welding current is very dense;
5. Accuracy. Considering the dose of energy consumed, a reliable seam of compact thickness is formed in the contact field. This method is widely used for fine welding of non-ferrous metal;
6. Profitability. The power consumption is 20 kVA maximum. This is done using power take-off due to the stabilization of the voltage in the network.

Diy assembly diagram of the unit

The primary winding is drawn through the diode bridge (rectifier), then it is connected to the voltage source. A signal is sent from the thyristor to the bridge diagonal. The thyristor is controlled by a special trigger button. The capacitor is connected to the thyristor, more precisely to its network, to the diode bridge, then it is brought out to the winding (primary). To charge the capacitor, an auxiliary circuit with a diode bridge and a transformer is switched on.

A capacitor is used as a pulse source; its capacitance should be 1000-2000 μF. For the construction of the system, a transformer is made from a core of type Ш40, the required size is 7 cm. To make the primary winding, a wire with a diameter of 8 mm is needed, which is wound 300 times. The secondary winding assumes the use of a copper bus, 10 windings. Almost any capacitors are used for the input, the only requirement is a power of 10 V., a voltage of 15.

Such a homemade capacitor welding works with the following sequence of actions:

1. Press the start button, it will start the time relay;
2. The transformer is turned on by thyristors, after the relay is turned off;
3. The resistor is used to determine the pulse width.

How does the welding process take place?

After the capacitor welding is assembled with our own hands, we are ready to start work. To begin with, it is worth preparing the parts by cleaning them from rust and other dirt. Before placing the workpieces between the electrodes, they are connected in such a position in which they need to be welded. Then the device starts up. Now you can squeeze the electrodes and wait 1-2 minutes. The charge that accumulates in the high-capacity capacitor will pass through the welded fastener and the surface of the material. As a result, it melts. When these steps are done, you can proceed to the subsequent steps and weld the rest of the metal.

Before welding at home, it is worth preparing materials such as sandpaper, grinder, knife, screwdriver, any clamp or pliers.

Conclusion

Condenser welding is very widely used both at home and in the industrial area, as we can see, it is very convenient and easy to use, plus everything has a lot of advantages. With the help of this information, you can take your knowledge to a new level and successfully apply spot welding in practice.

Sergey Odintsov

electrod.biz

Capacitor welding is a stored energy welding method. Energy charges will accumulate in capacitors during charging from a rectifier, after which they will be transformed into heat. It will be formed in the process of current flow between the parts to be welded. That is why capacitor welding is also called resistance welding.

Electric circuit of spot micro-welding.

Items that will be needed:

• welding device;
• electrode;
• transformer;
• wire;
• capacitor.

The difference between the spot welding method from other existing ones

Capacitor welding with a capacitor discharge through the primary winding of the transformer: a-diagram of the process; b-current diagram.

The main difference between this connection method is environmental friendliness. A standard capacitor welder operates at high currents, which makes it possible to obtain excellent weld quality with low energy consumption.

The capacitor welding method, like accessories for it, is most often used in cases where it is necessary to perform microwelding or join workpieces of large sections and thicknesses. DIY spot welding is as follows:

1. Capacitors store energy in the required amount.
2. The charges are converted into heat, which is used for welding.

You should be aware that spot welding is environmentally friendly, as it has virtually no impact on the environment. The devices used do not require liquid for cooling, as no heat is generated from them. This significant advantage makes it possible to increase the life cycle of the entire device to obtain permanent connections.

Instead of typical cylinders, special servo drives are used in the designs, and therefore there is no need for a pneumatic connection. Built-in components allow you to build up the welding force quickly and efficiently. In this case, the electrodes will act delicately on the base.

Condenser welding has the following advantages:

• the ability to weld at high speed;
• the accuracy of the connection of elements;
• high level of environmental friendliness;
• connection reliability;
• durability of welding devices.

Capacitor welding circuit.

Due to the high speed, spot welding will not deform and melt the metal. The devices act gently on various workpieces. Excellent quality indicators can be obtained with the contact or impact method of joining workpieces. For example, the shock-capacitor method is best used for joining non-ferrous metals and their alloys. As a result, the seam will turn out to be aesthetic, reliable, and the process of obtaining permanent joints will take a small amount of time.

Capacitor welding is often used in industrial environments due to its combination of performance characteristics. A technological phenomenon is formed, during which the inseparable contact of metal blanks is made due to the release of heat. At the same time, dirt, oxide films, various inclusions and bulges will be removed from the welding place by means of compression force. As a result, there will be connections between the atoms of the bonded coatings.

Energy charges will accumulate when charged from a generator or rectifier. Energy adjustment can be made by changing the voltage and charging capacity.

Existing varieties of spot welding

Design of transformers for spot welding.

Sometimes a connection without transformers is used. Capacitors in this case will discharge energy to the connected base. The following charging schemes are allowed:

1. 1000 μF devices will store energy for voltages up to 1000 V by means of a step-up transformer, while the welding time will be 0.005 s. The welding current is in the range from 10 to 100 A. This method is dangerous to humans due to the high voltage.
2. 40,000-400,000 μF devices will store energy for voltages up to 60 V by means of a step-down transformer. The welding time can be up to 0.6 s. in this case, the welding current is in the range from 1000 to 2000 A.

In other cases, welding using transformers is used. In this case, the capacitor will discharge the energy charge to the primary winding of the transformer device.

Types of contact welding: a - butt welding; b - point; в - roller; 1 - welding seam; 2 - electrode; 3 - parts to be welded; 4 - movable plate with a movable part; 5 - welding transformer; 6 - fixed plate.

In this case, the parts to be connected are placed in the welding circuit, which is connected to the secondary winding of the transformer. This connection method is used as microwelding with the following parameters:

• charging voltage - 1000 V;
• welding time - 0.001 s;
• welding current - 6000 A;
• capacitance of capacitor devices - 1000 μF.

The capacitor will store energy to a specific amount when the lever is placed on the left. With the right, the heat exchangers are discharged to the primary winding of the transformer structure. The capacitor connection method in the secondary winding is induced by an electromotive force. This force determines the amperage in the welding chain.

Non-ferrous metal spot welding

Non-ferrous metals contrast with common steel. In this case, various heat treatment methods can be used. Everything will depend on the type of metal to be joined. Welding of such metals has the following features:

• melting temperature;
• density;
• affinity for atmospheric gases;
• mechanical performance at low and high temperatures.

Spot welding torches.

According to the totality of data, metals can be distinguished:

• heavy colored;
• active and refractory;
• lungs.

From the first group, metals can be melted by spot welding without much difficulty. For copper wires, in most cases, mechanized devices are used. They are able to provide a high quality connection and maintain the original dimensions of the workpieces.

For the processing of metals of the other two groups, devices with a high concentration of energy will be needed. Do-it-yourself welding of blanks from these groups is extremely rare, since in this case volatile harmful compounds can form.

Capacitor welding technology

The process of joining workpieces by the point method consists of several stages. First of all, the workpieces to be joined will need to be combined in the required position, placed between the electrodes of the welding device, and then pressed against each other. After that, they will need to be heated to a state of plasticity and subjected to subsequent plastic deformation. In industrial conditions, in the process of using automatic structures, the welding frequency reaches 600 points / min. In order to be able to make high-quality capacitor welding with your own hands, you will need to maintain the same speed of movement of all electrodes. It is imperative to ensure the required pressure and full contact of the workpieces being welded.

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The workpieces will be heated due to the passage of the welding current in the form of a short pulse. The pulse duration depends on the welding conditions and can be from 0.01 to 0.1 s. This pulse will ensure the melting of the element in the zone of action of the electrodes and a common liquid core of the two blanks is formed. The core diameter can be from 4 to 12 mm. After the current pulse ceases to act, the workpieces will be held under pressure for some time so that the formed core can cool down and crystallize.

Heating time and pressure

The duration of heating or passage of the welding current can vary, it depends on the welding conditions and the power of the structure used. In the case of joining elements made of steels that are prone to hardening and cracking, it will be necessary to increase the heating duration. This is done in order to be able to slow down further cooling of the metal. Welding stainless steel workpieces will need to be done with a minimum heating time. This is necessary in order to be able to prevent the danger of heating the outer base of the junction point to the temperature of the transformation of the structure. You should be aware that as a result, the high anti-corrosion properties of the outer layers of the metal may be violated.

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The force of pressure between the electrodes must ensure a reliable connection of the workpieces at the welding point. It depends on the type of metal to be joined and the thickness of the workpieces being welded. The pressure after heating is important, since its value will provide a fine-grained structure of the metal at the junction, while the strength of the junction point will be equal to the strength of the base metal.

Features of the choice and use of electrodes

Position of the electrode when welding.

Factors on which the quality of welding depends:

1. Welding quality will depend on the correct choice of the copper electrode diameter. The diameter of the connection point must be several times greater than the thickness of the thin welded joint element.
2. Pressing the blanks at the moment of passage of the welding pulse can provide the appearance of a band for compaction near the molten core. This eliminates the need for any additional security measures at the junction.
3. In order to be able to improve the crystallization of the molten workpiece, the electrodes will need to be unclenched with a short delay after the passage of the welding pulse.
4. In order to get a high-quality and reliable weld seam, the bases to be joined will need to be prepared first. In this case, we mean cleaning the elements from rust.
5. The distance between the connection points should ensure that current shunting through the near points is reduced. For example, to connect two workpieces with a thickness of 2-5 mm, the distance between the connection points will vary from 15 to 50 mm.

Electrodes used for capacitor welding must provide strength in the range of operating temperatures, high electrical and thermal conductivity, and ease of processing. Some bronzes, which include cobalt and cadmium, meet similar requirements. Copper alloys with chromium are also suitable. You should know that in terms of heat and electrical conductivity, copper is significantly superior to bronze and alloys, but this metal is many times worse in terms of wear resistance. Therefore, an EV type alloy is best suited for such purposes, which is almost pure copper with the addition of chromium and zinc.

To reduce the wear of the electrodes, during use, they must be intensively cooled with water.

Seam welding diagram.

The copper wire welding device can be easily assembled by yourself. To do this, you should purchase a 450 W transformer. The transformer is needed of a standard type, with a primary copper winding 0.75x2 mm thick and a secondary winding with a 6 mm aluminum power cable. In this case, you will also need a carbon electrode.

The copper wire welding machine operates on an alternating current of 35 to 40 A. The highest voltage point is 15 V. Multiple clamps can be used as an electrode holder. The conductor for the device being manufactured can be a carbon electrode, which is made from a trolleybus contact brush.

If you use this device carefully, it can last for several years. It is necessary to monitor the contacts, as well as to ensure that the battery is not discharged. The copper wire welding scheme does not imply the use of devices with high resources. A self-made device is able to perfectly cope with significant amounts of work.

It should be noted: welding work in this case can be automated, which is a significant advantage.

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Condenser welding is a complex process, so you need to know all the nuances.