Homemade capacitor welding. Capacitor welding review and manufacture. Capacitor Welding Application

Greetings to all readers of the site " Volt-Index”, 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 do not heat up excessively, you can. In 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 trouble-free. This is transformerless or impact resistance welding, so as not to get confused later, I want to say that the transformer is in our diagram.

Yet there is, 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 transformers.

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

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

The principle of operation is the following.

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

To be honest, the capacitances may differ, 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 removable contacts are connected. Moreover, as these contacts, the parts themselves can sometimes be used, which must be welded together.

The momentary discharge of the capacitance of powerful capacitors causes a huge current surge, the process is very short-lived, but the currents can reach tens of thousands of amperes, depending on the capacitance 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 around 40 volts. Such tension is completely safe for humans, although it all depends on the physiology of the individual. For someone and 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 outputs 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 may 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, which provides the desired voltage at the output, will do. The charging time of the capacitors will depend on the current of the secondary winding.

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

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

The device is provided with a thyristor contactor.

When a 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, a thyristor T 171-320 was taken.

The short-term surge current in our system can reach 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 early indicated voltage.

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

A chain of a resistor, an LED and a zener diode is an indicator of the charge of the capacitors, 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 pieces of smaller ratings 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 can handle it, and an increase in capacitance will make it possible to weld 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 in parallel to the capacitors. To discharge the latter after turning off the device. A button was also provided for an emergency discharge of the tank. 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 incorporated into the primary circuit of the transformer. This will allow you to adjust the voltage on the capacitors and select the optimal voltage for welding parts from certain metals.

Developed in the 1930s, capacitor welding technology has become widespread. A number of factors contributed to this.

• The simplicity of the design of the welding machine. If desired, it can be assembled by hand.
• Relatively low energy consumption of the working process and low loads created on the electrical network.
• High productivity, which, of course, is 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 parts, as well as on specific surfaces, where the use of conventional methods would inevitably lead to undesirable deformations of the material.

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

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

1. Short time of thermal heating of connected details. 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.

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

1. Spot capacitor welding. Using a short pulse of current emitted by a capacitor, they connect parts in precision engineering, electrovacuum and electronic technology. This technology is also suitable for welding parts that differ significantly in thickness.
2. Roller seam allows you to get a completely tight connection, consisting of many overlapping welding points. This leads to the use of technology in the manufacturing process of electrovacuum, membrane and bellows devices.
3. Butt welding, which can be performed both by contact and non-contact methods. In both cases, melting occurs at the junction of the parts.

Application area

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

• Automotive industry, where it is necessary to securely interconnect body panels made of sheet steel.
• Aircraft industry, which places special demands on the strength of welds.
• Shipbuilding, where, taking into account the large volume of work, saving electricity and consumables gives a particularly tangible result.
• Production of precision instruments, where significant deformations of the connected parts are unacceptable.
• Construction, in which sheet metal structures are widely used.

Easy-to-device and easy-to-use equipment is in demand everywhere. With it, you can set up 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 you can easily find the desired scheme and detailed description on the network. Such a device works as follows:

• The current is directed through the primary winding of the supply transformer and the rectifying diode bridge.
• The control signal of 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 powered from the auxiliary network. When the button is pressed, this charge rushes through the resistor and the auxiliary thyristor towards the welding electrode. The auxiliary network is switched off.
• To re-charge the capacitor, you need to release the button, opening the resistor and thyristor circuit and reconnecting the auxiliary network.

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

This is only a basic description of the operation of the simplest equipment for capacitor welding, the device of which can be changed, depending on the tasks being solved and the required output characteristics.

Need to know

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

• The recommended capacitance of the capacitor should be about 1000 - 2000 microfarads.
• For the manufacture of a transformer, the core of the Sh40 variety is best suited. Its optimal thickness is 70 mm.
• The parameters of the primary winding are 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 these data, it is possible to assemble a fully functional spot welding device. 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 begin to manufacture various parts.

Contact or capacitor welding is one of the most common types of joining metal products and parts. It is widely used not only in industrial, but also at home. That is why the question of assembling a capacitor welding machine with your own hands remains relevant and is of interest to many craftsmen.

How Capacitor Welding Works

The capacitor welding machine is a body equipped with protruding working claws. Each has electrodes. The connection of bars and metal plates occurs due to the location of the electrodes opposite each other.

The process begins with clamping the workpieces to be welded between the claws. After turning on the device, a current is carried out with great force through the electrodes and the parts to be welded. As a result, a liquid core is formed in the right place, the lattice of molecules is destroyed and they are combined. The thickness of the weld depends on the power of the current and the electrodes used. The material melts and contracts.

Capacitor spot welding is successfully used in domestic, home conditions. Thanks to the transformer, it is possible to convert the current from the network, lowering and amplifying it to the required parameters. The device creates a current pulse, the duration of which is only 0.1-1.5 seconds. During this short time, a point is formed that holds the two metal parts together. The resulting tubercle is cleaned with a brush or grinder, giving the product an aesthetic appearance.

Advantages

Independent capacitor welding is known for a number of advantages:

• connection of small and thin elements is possible;
• fast connection;
• reliability of the connecting seam;
• seam accuracy;
• connection of different types of metals;
• profitability;
• accessibility for beginners.

With the help of spot or capacitor welding, very thin parts can be joined without overheating and undercuts. The device is designed in such a way that the process does not take much time. A sufficient electric current is created, reliably connecting the parts.

The seam looks neat, without the top layer of deposited material. To improve the appearance of the product, it is enough to clean the place of the alloy with a brush. Even precious metals can be combined. To make the alloy, there is no need to use filler materials, which reduces the cost of the method. Training and performance of welding works is available to a wide range of employees.

Scheme of self-assembly of the device

The components of capacitor welding are quite simple, so the unit can be assembled independently, following a specific pattern. The main element is a transformer that can significantly reduce the strength of electric current from a household network. The optimal parameters are the numbers - 10-12 V. In this case, it is necessary to achieve an electricity strength of 300-500 A. With such indicators, it is possible to perform capacitor welding at home.

The operation of the device is based on the conversion of the voltage used and its transfer to the storage devices. In this case, the accumulators are capacitors, the capacitance of which should be within 46 microfarads. The design is equipped with a diode bridge and two diodes. The welding process is controlled using the REK 74 relay. This device supplies current to the built-in electrodes, thus carrying out the process.

The capacitor apparatus must contain a special machine that will operate during an overload. To prevent overheating, a cooler is used, which is built into the back of the condenser structure. A start button is installed on the claws, with the help of which the welding process is started. The welder clamps the sides of the product to be joined between the claws, performs capacitor spot welding.

welding process

The process of welding with a capacitor unit begins with the preparation of products. The connection sides are cleaned of all existing contaminants. If this is not done, the seam may not be reliable enough.

The prepared elements are connected in the right place, placed between two electrodes, one of which is movable and the other is stationary. With the help of claws with electrodes, the metal parts to be welded are squeezed with force. After pressing the start button, an electric discharge occurs.

In the place where the electrodes are connected, a welding seam is formed. Claws should be unclenched after a while - it is necessary to allow the welding joint to cool and crystallize under pressure. Then the parts are moved to connect the next section. For the convenience of capacitor welding, it is necessary to acquire pliers, sandpaper, a screwdriver, a knife and a grinder.

Contact block and sequence of actions

A do-it-yourself block for capacitor welding can be assembled at home. Many people use a microwave element as a transformer. In order for the device to cope with its functions - reducing voltage and increasing amperes - the primary layer of the winding is removed. Instead, they start a cable for welding. There is enough space for three turns.

Having completed the basics, proceed to install the relay and diode bridge. All parts must be mounted in close proximity to the transformer. The block is equipped with an automatic machine. A cooler or a small fan is attached to the back wall, which is necessary for cooling the unit. For the arrangement of elements, it is advised to use a dielectric base.

Working bodies are made of a profile or a bar. The lower part with the electrode is stationary. The upper part is fixed with a rod between the uprights, it is movable. The top element is in a raised position, in which it is fixed by an attached spring.

The thickness of the copper electrodes must match the thickness of the cable for welding the secondary winding. They are bolted to the claws. The terminals from the transformer are also connected here. The button for starting the capacitor welding process is displayed on the body so that it is convenient to turn it on.

At the first stage of work, the parts are cleaned of foreign particles. Then they are connected and placed in the welding field formed by the electrodes. The button starts the device by giving an impulse. Upon completion of the contact, the electrodes are moved apart.

Capacitor welding is one of the types of contact welding, which is actively used in industry, as well as for do-it-yourself welding operations in everyday life.

The technological scheme of the operation is as follows: in capacitors, when they are charged from a rectifier, energy is accumulated, which, when discharged, is transformed into thermal energy.

With the help of this energy, the edges of metal products are connected. We will tell you how to do capacitor welding with your own hands: a diagram and a description of the technology.

Do-it-yourself condenser was developed back in the 30s of the XX century. Today, this technology is actively used by industrial enterprises and craftsmen to perform household welding operations.

This technology is especially popular in vehicle body repair shops: unlike the arc method, the capacitor method of creating a weld does not burn through and deform thin walls of body parts sheets. Subsequently, the connected body parts do not need additional straightening.

This technology is used in radio electronics to connect products that are not soldered using conventional fluxes or fail when overheated.

Capacitive welding devices are actively used by jewelers in the manufacture and repair of jewelry, in enterprises that produce communication cabinets, laboratory, medical, food equipment, in the construction of buildings, bridges, utilities.

Such a wide distribution can be explained by the action of a number of factors:

• simple design of the welding machine, which, if desired, can be assembled by hand;
• spot welding is characterized by relatively low energy consumption and low loads created on the electrical network;
• high performance indicators, which is extremely important in mass production;
• the ability to reduce the thermal effect on the surfaces to be joined, which makes it possible to weld small parts and work with those structures whose walls are excessively thin and can be deformed during conventional welding.

On a note! The advantage of capacitor welding technology is the simplicity of its implementation: even an average skill level allows the master to create high-quality welds.

The method of capacitor welding of the product.

The rules for the implementation of welding operations using the energy of capacitors are regulated by GOST. The principle of technology is based on the transformation of the energy of the electric charge accumulated on the capacitors into thermal energy.

When the electrodes come into contact, a discharge occurs and an electric arc of short duration is formed. Due to the heat generated by it, the edges of the metal parts to be joined are melted, forming a weld.

In capacitor welding, the current is applied to the welded electrode in the form of a short-term high-power pulse, which is obtained by installing high-capacity capacitors in the equipment.

In the case of resistance welding, the current is continuous. This is the main difference between these types of welding operations.

As a result, the master can achieve high rates of two important parameters:

• it takes much less time to heat the connected parts, which is especially valuable for manufacturers of electronic components;
• the current used to connect the parts has a high power, so the welds themselves are of better quality.

In the process of welding operations, for fastening elements and assemblies of different products, studs of different types and purposes may be required.

The advantage of capacitor welding is the ability to reduce the area of ​​thermal impact, reduce stress and reduce to zero the risk of surface deformation due to the high energy density and short duration of the weld pulse. The technology allows you to work with non-ferrous metals with a small thickness.

We also note that a huge plus of the capacitor welded apparatus is its compactness. To apply this technology in practice, a powerful power source is not required, the device can be charged between moving the electrode to the next point.

Do-it-yourself capacitor welding

Contact welding is used by welders, so it is not difficult to buy a factory machine for its implementation.

Models as opposed to spot welding units , they are distinguished by a simple design, simple operation and are inexpensive, but many craftsmen still decide to assemble a capacitor-type welded apparatus with their own hands. This allows you to save money, realize your own talent.

Welding temperature of various materials.

Completing this task requires the master to:

• find on the Internet the necessary scheme and a detailed description of the structural features of the unit;
• understand the mechanism of operation of the device;
• choose relevant materials and fixtures: welded studs, welded electrodes, etc.

The mechanism of operation of the apparatus for capacitor welding:

• the current is directed through the primary winding of the supply transformer, a rectifier represented by a diode bridge;
• on the diagonal of the bridge, the control signal of the thyristor with the start button is supplied;
• a capacitor is inserted in the thyristor circuit to accumulate the weld pulse, which must also be connected to the rectifier diagonal and the primary winding of the transformer coil.

The connection of sections of metal structures is carried out with a strong electrical influence accumulated in two-terminal networks, and the process itself is divided into three categories:

1. Contact welding.
   It involves a tight pressing of the workpieces to each other, followed by contact of the electrodes to this place. The energy supplied to a limited space is so great that it leads to rapid melting and further attachment of the edges of the parts.
2. Impact technology.
   It also involves the connection of individual metal parts into a single structure, but electricity is supplied to the place of welding in the form of a short-term shock. This technology makes it possible to reduce the duration of the welding operation to 1.5 m/s;
3. Dot technique.
   When using this type of welding, two copper contacts are required that touch the object from two faces. As a result, the products are fastened at the point of contact with the electrode.

If necessary, hang devices fixed with nuts on a thin-sheet metal structure, you can use the same capacitor welding.

With its help, a special stud for capacitor welding is welded onto the wall of the structure, and the device is already fixed on it. The stud is placed against the base metal and the equipment is set up to perform the welding operation.

The arc melts the base of the stud and the area of ​​the base metal corresponding to it, after which the product is introduced into the weld pool and fixed on the surface until the metals cool. This will take milliseconds to complete, but it will be reliable and durable.

Scheme for capacitor welding

Scheme of capacitor welding.

Do-it-yourself capacitor spot welding is easily performed even by an inexperienced welder.

Its basis is an electrical circuit using capacitors:

1. The primary winding is carried out through the rectifier presented.
   Then it is connected to a voltage source.
2. The thyristor sends a signal to the bridge diagonal and is controlled by the start button.
   The capacitor is connected to the thyristor network, diode bridge and output to the primary winding.
3. You can charge the capacitor by turning on the auxiliary circuit with a rectifier and a transformer.

Do-it-yourself capacitor welding of batteries is carried out in the following sequence of actions on the part of the master:

• pressing the start button that starts the time relay;
• turning on the transformer using thyristors, after the relay is turned off;
• using a resistor to determine the pulse duration.

Requirements for capacitor welding

Welded capacitors are used on an industrial scale and in small workshops. In any case, do not violate the welding technology for batteries with your own hands, otherwise the welds will turn out to be of poor quality.

Electrical circuit of capacitor welding.

Compliance with the following conditions will allow you to get a really high-quality result of work:

• ensure the supply of a short-term pulse for a time interval of up to 0.1 s, as well as the subsequent accumulation of energy charge from the power source for a new pulse in the shortest possible time;
• take care of good contact of the parts to be welded by sufficient electrode pressure on the parts at the moment the welding pulse is applied;
• release the electrodes with a delay so that the melt cools under pressure and the mode of crystallization of the weld metal improves;
• the diameter of the point formed on the metal from contact with the electrode should be 2 times larger than the thinnest workpiece to be welded;
• thoroughly clean the surface of the workpieces to be welded before welding, so that oxide films and rust do not provoke significant resistance to current.

On a note! The most successful version of electrodes for capacitor welding is copper-plated wire.

Do-it-yourself capacitor spot welding can only be done if the unit is assembled with at least two blocks: a source of a weld pulse and a welding block. It is also extremely important to provide for the possibility of adjusting the welding mode and protection.

It is especially important to adhere to the safety rules with a welded machine, which include the following points:

• to protect the eyes from sparks from the welded machine, put on a special mask;
• gloves will help protect the skin of the hands from burns, and the body - a special protective overalls;
• the welder's feet are put on boots with a sole made of dense material that does not allow damage to the fingers and foot during work.

Contact block designs

The contact block of capacitor welding is responsible for fixing and moving welded. In most cases, the fixation of both rods is carried out manually.

Scheme of shock-type capacitor welding.

A better version provides a secure fixation of the lower rod, but leaves the upper rod movable. In this case, the upper copper rod is fixed so that it moves freely in a vertical plane. And the bottom one is left in a stationary state.

Also, a screw sample regulator is mounted on the upper part, which allows you to create additional pressure. The main thing is that the upper platform and the base of the power unit have good insulation from each other. Some models are equipped with a lantern on top, which makes the work more comfortable.

When designing capacitor welding with your own hands, you will need to have the following details:

• capacitor, with a capacity of 1000-2000 microfarads, a power of 10 V, a voltage of 15;
• a transformer of the required size - 7 cm, made from a Sh40 type core;
• primary winding made of three hundred layers of wire with a diameter of 8 mm;
• secondary winding of ten windings of a copper bus;
• starter of the MTT4K series, including parallel thyristors, diodes and a resistor.

On a note! If the work requires joining workpieces up to 0.5 cm, you will need to apply additional adjustments to the design scheme.

Features of the homemade unit

It is possible to carry out shock capacitor welding using a special factory-made apparatus, which is sold in specialized stores. However, it is quite realistic to make capacitor-type welding on your own in a small workshop.

Self-made units demonstrate high performance parameters and are not inferior to factory models in operation.

Homemade capacitor welding machine.

Before work, a home-made welding machine that uses the energy of capacitors is set with the main operating parameters:

• stress in the zone of metal products;
• type and strength of current;
• the duration of the weld pulse;
• the number and dimensions of the welded wire used in the work.

The control boards present in the design of both factory and home-made welding units provide the master with the opportunity to bring the incoming voltage and constant current to a stable value. It is important to equip a home-made unit with a switch for welding with electrodes without much difficulty.

Home-made units, like factory models, are durable, easy to use, if they are designed according to the scheme, technological requirements and safety standards.

And the technical parameters of the model made on its own must correspond to the characteristics of the factory designs. Then the device will allow even an inexperienced welder to perform reliable and durable welds using the capacitor welding method.

But do not forget that a significant share of success in performing welding operations depends on the thoroughness of the preparatory work. Be sure to make sure that the surfaces to be welded are free of dirt, dust, rust before starting work.

Such defects can negate the efforts of the welder, becoming an obstacle to the quality connection of the melted edges of the products.

Summing up

Capacitor welding is relevant when it is necessary to connect non-ferrous metal parts into a single structure.

The technology has a number of advantages, among which the ability to reduce the area of ​​thermal exposure, reduce stress and eliminate the risk of deformation of metal surfaces is especially valuable. Capacitor welding machines are easy to use and easy to assemble with your own hands, which saves money.

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

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 be easily moved around the working area.

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

• high work productivity;
• durability of the equipment used;
• the possibility of connecting various metals;
• low level of heat emission;
• no additional consumables;
• the accuracy of the connection of elements.

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

Features and specifics of application

The process of joining workpieces involves contact welding, for 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 decreases.

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 gained particular popularity in workshops designed to repair vehicle bodies. During the work they do not burn through and are not subjected to deformation. The need for additional straightening is eliminated.

Basic process requirements

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

1. The pressure of the contact elements on the workpieces directly at the moment of impulse must be sufficient to ensure a reliable connection. Opening the electrodes should be done with a slight delay, thereby achieving the best mode of crystallization of metal parts.
2. The surface of the workpieces to be joined must be free of contaminants so that oxide films and rust do not cause too much resistance when the electrical current is applied directly to the workpiece. 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 must be at least 2-3 times greater than the thickness of the element to be welded.

Technological methods

There are three options for influencing workpieces:

1. Capacitor spot welding is mainly used to connect parts with different thickness ratios. It is successfully used in the field of electronics and instrumentation.
2. Roller welding is a certain number of spot joints made in the form of a continuous seam. The electrodes are like rotating coils.
3. Impact capacitor welding allows you to create elements with a small cross section. Before the collision of the workpieces, an arc discharge is formed, which melts the ends. After the parts come into contact, welding is carried out.

As for the classification according to the equipment used, it is possible to divide the technology by the presence of a transformer. In its absence, the design of the main device is simplified, and the bulk of heat is released in the zone of direct contact. The main advantage of transformer welding is the ability to provide a large amount of energy.

Do-it-yourself capacitor spot welding: a diagram of a simple device

To connect thin sheets up to 0.5 mm or small parts, you can use a simple design made at home. In it, the impulse is fed through a transformer. One of the ends of the secondary winding is connected to the array of the main part, and the other - to the electrode.

In the manufacture of such a device, a scheme 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 having a capacitance of 1000 - 2000 microfarads. For the manufacture of a transformer, a Sh-40 core with 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 PEV. A thyristor with the designation KU200 or PTL-50 is suitable for control. The secondary winding with ten turns can be made of a 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 will be possible to connect wires with a cross section of up to 5 mm, as well as thin sheets with a thickness of not more than 1 mm. To control the signal, a non-contact starter marked MTT4K 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 the table. You can find the necessary 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 is made of a copper bus.

The work of a homemade apparatus occurs according to the following scheme. When the start button is pressed, the installed relay is activated, which, using thyristor contacts, turns on the transformer of the welding unit. Shutdown occurs immediately after the capacitors are discharged. The impulse action is adjusted by means of a variable resistor.

Contact block device

The manufactured fixture for capacitor welding should have a convenient welding module that provides the ability to fix and move the electrodes without hindrance. The simplest design involves manual holding of the contact elements. In a more complex version, the lower electrode is fixed in a stationary position.

To do 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 off. The second electrode is attached to a platform that can move. In any case, adjusting screws must be installed, with which additional pressure will be applied to create additional pressure.

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

Work procedure

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

1. At the initial stage, the elements to be connected are prepared properly. Contaminants in the form of dust particles, rust and other substances are removed from their surface. The presence of foreign inclusions will not allow to achieve high-quality docking of workpieces.
2. 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 action on the workpiece stops, the electrodes can be moved apart. The finished part is removed. If there is a need, then it is installed at a different point. The thickness of the element to be welded directly affects the size of the gap.

The use of ready-made devices

Work can be carried out using special equipment. This 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 for connecting metal elements allows not only welding steel products. With its help, you can 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.