Scheme and description of contact capacitor welding for batteries. Scheme and principle of operation of home-made capacitor welding Home-made machine for spot welding of capacitors

13.07.2023

How is capacitor welding done by hand? Do-it-yourself capacitor welding scheme and description

Scheme and description of capacitor welding

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 release;
no additional consumables;
the accuracy of the connection of elements.

However, there are situations when it is not possible to use a capacitor welding machine 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, thin sheets of metal are not burned 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.

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.
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.
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:

Capacitor spot welding is mainly used to connect parts with different thickness ratios. It is successfully used in the field of electronics and instrumentation.
Roller welding is a certain number of spot joints made in the form of a continuous seam. The electrodes are like rotating coils.
Impact capacitor welding allows you to create butt joints of 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 a parallel connection. In 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.

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.
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.
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.

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Do-it-yourself capacitor welding - diagram and description

April 8, 2017

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

As soon as it became possible to carry out turned 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 for home use with your own hands? We will try to analyze this issue in detail today.

How is the capacitor method different from other types?

The first difference that catches the eye is the speed of welding 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 carry out welding of large sections. It happens according to this principle:

Capacitors collect the required amount of energy;
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 emissions. 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, which receive a short-term current. Then an arc is formed between the electrodes, and it heats the metal, melting it. The welding pulse comes into operation within 0.1 sec., it provides a common melt core for both parts of the workpieces to be welded. When the impulse is removed, the parts continue to compress under the pressure of the load. The result is a common weld.

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

Types of spot welding

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

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

Advantages

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

With stable operation, it is possible to save electricity;
Reliability and practicality. The speed of work allows spot welding to be available with air cooling;
Work speed;
The welding current is very dense;
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 thin welding of non-ferrous metal;
Profitability. The power consumption is 20 kVA maximum. This happens with the help of power take-off due to voltage stabilization in the network.

Do-it-yourself unit assembly scheme

Through the diode bridge (rectifier), the primary winding is carried out, then it is connected to a voltage source. From the thyristor there is a signal to the bridge diagonal. The thyristor is controlled by a special button to start. The capacitor is connected to the thyristor, more precisely, to its network, to the diode bridge, then it is brought to the winding (primary). To charge the capacitor, an auxiliary circuit with a diode bridge and a transformer is turned on.

As a pulse source, a capacitor is used, its capacitance should be 1000-2000 uF. For the design of the system, a transformer is made from a Sh40 type core, the required size is 7 cm. To make the primary winding, you need a wire with a diameter of 8 mm, which is wrapped 300 times. The secondary winding involves the use of a copper bus, 10 windings. Almost any capacitors are used for 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 scheme. For more convenient signal control, use the starter of the MTT4K series, it includes parallel thyristors, diodes and a resistor. An additional relay will allow you to adjust the working time.

Such home-made capacitor welding works with the following sequence of actions:

Press the start button, it will start the time relay;
The transformer is turned on with the help of thyristors, after the relay is turned off;
The resistor is used to determine the pulse duration.

How is the welding process?

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 of rust and other dirt. Before placing the blanks between the electrodes, they are connected in 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 a 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 next 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

Capacitor 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 it has a large number of advantages. With the help of the above information, you will be able to take your knowledge to a new level and successfully apply spot welding in practice.

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Do-it-yourself capacitor welding: technology and varieties

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

Items that will be needed:

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

The difference between the spot welding method and other existing ones

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

The main difference between this method of connection is environmental friendliness. The standard capacitor welding device operates at high currents, which makes it possible to obtain a weld of excellent quality with low power consumption.

The capacitor welding method, as well as devices for it, is most often used in cases where it is necessary to perform micro-welding or connect workpieces of large sections and thicknesses. Do-it-yourself spot welding is as follows:

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

You should know that spot welding is environmentally friendly, as it has practically no effect on the environment. The devices used do not need liquid for cooling, as no heat is generated from them. Such a 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 accumulate welding force quite quickly and efficiently. In this case, the electrodes will act delicately on the base.

Capacitor welding has the following advantages:

the ability to weld at high speed;
accuracy of connection of elements;
high level of 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 on various workpieces in a gentle manner. Excellent quality indicators can be obtained with the contact or impact method of connecting workpieces. For example, the shock-capacitor method is best used for joining non-ferrous metals and alloys based on them. As a result, the seam will turn out to be aesthetic, reliable, and the process of obtaining one-piece joints will take a small amount of time.

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

Energy charges will accumulate when charging from a generator or rectifier. You can adjust the energy 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:

1000 uF devices will store energy up to 1000 V by step-up transformer, while welding time will be 0.005 s. The welding current is in the range from 10 to 100 A. This method is dangerous for humans due to high voltage.
40000-400000 uF devices will store energy for voltages up to 60 V by means of a step-down transformer. Welding time can reach 0.6s. while 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 charge of energy to the primary winding of the transformer device.

Types of resistance welding: a - butt welding; b - dotted; in - roller; 1 - welding seam; 2 - electrode; 3 - welded parts; 4 - movable plate with a moving 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 micro welding with the following parameters:

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

The capacitor will store energy up to a certain 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 method of connection in the secondary winding is induced by an electromotive force. This force determines the current strength in the welding chain.

Welding of non-ferrous metals by spot welding

Non-ferrous metals contrast with ordinary steel. In this case, various methods of heat treatment can be used. Everything will depend on the type of metal being joined. Welding of such metals has the 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 connecting workpieces in a dotted way consists of several stages. First of all, the workpieces to be joined will need to be aligned 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 to be welded.

The workpieces will be heated by 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 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 and crystallize.

Heating time and pressure force

The duration of heating or passage of the welding current may vary, it depends on the welding conditions and the power of the structure used. In the case of joining elements from steels that are prone to hardening and cracking, it will be necessary to increase the heating time. This is done in order to be able to slow down the further cooling of the metal. Welding stainless steel blanks 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 connection 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 pressure force between the electrodes must ensure a reliable connection of the workpieces at the welding site. It depends on the type of metal to be joined and the thickness of the workpieces to be welded. The pressure after heating is important, since its value will provide a fine-grained metal structure at the junction, while the strength of the junction 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:

The quality of welding will depend on the correct choice of the diameter of the copper electrode. The diameter of the connection point must necessarily exceed the thickness of the thin element of the welding connection by several times.
By pressing the workpieces at the moment of passage of the welding pulse, the appearance of a belt for sealing near the molten core can be ensured. As a result, no additional security measures are required at the connection point.
In order to be able to improve the crystallization of the molten workpiece, the electrodes will need to be opened with a slight delay after the passage of the welding pulse.
In order to be able to obtain a high-quality and reliable welding seam, the bases to be joined will need to be prepared first. In this case, we mean cleaning the elements from rust.
The distance between connection points should ensure that current shunting through nearby 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.

The electrodes that are used for capacitor welding must provide strength in the operating temperature range, high electrical and thermal conductivity, as well as ease of processing. Some bronzes meet similar requirements, which include cobalt and cadmium. Copper alloys containing chromium are also suitable. You should know that in terms of thermal 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 alloy of the EV type, which is almost pure copper with the addition of chromium and zinc, is best suited for such purposes.

To reduce the wear of the electrodes, during use it is necessary to cool them intensively with water.

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

A device for welding copper wire can be easily assembled by yourself. To do this, purchase a transformer with a power of 450 watts. 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 need a carbon electrode.

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

If you carefully operate this device, 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 homemade device can perfectly cope with significant amounts of work.

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

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

moyasvarka.ru

Do-it-yourself welding machine on capacitors

The device that we will present in this article is called "capacitor welding". This welding can connect very small or thin objects and parts.
Its difference from standard spot welding is that the heating of the junction of parts is carried out due to the energy of the discharge of capacitors.

Lots of electronic fun stuff in this Chinese store.

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

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

izobreteniya.net

Greetings to all readers of the Volt-Index website, sometimes doing 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.

Attached files: DOWNLOAD.

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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.

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.
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 requirements of production, one of three technological methods is chosen.

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.
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.
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.

Using the described technology, it is possible to connect 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 occur during its processing, it is necessary to increase the pulse duration, thus raising the heating temperature.

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Capacitor welding using spot, contact and shock technology: equipment arrangement

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 of an electric charge accumulated on a block of capacitors onto 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

Capacitor welding is most widely used in instrumentation. It is capable of welding metals up to 1.5 mm, and the thickness of the second part can be much larger. In the welding of thin products in terms of economy, productivity and quality, capacitor welding has no competitors.

It is 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 characterized by simplicity and a minimum of details.

Depending on the characteristics of the formation of the seam, capacitor welding is divided 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 electrovacuum devices. A continuous, tight seam is obtained due to the fact that point connections are made with overlap. The role of the electrodes is performed by rotating rollers.

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 connection 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 between the parts.

Advantages

The advantage of capacitor welding is that due to the high energy density and the 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 is used only when working with thin metals.

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

There are practically no harmful gases during the welding process. The device is very economical, all stored energy is used to melt 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.

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

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

The capacitive welding machine is used for joining all kinds of steels, 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 micro-welding, for example, in a watch mechanism. The condenser apparatus can weld refractory tungsten filaments, used in jewelry.

Technological features

Depending on the technological process, capacitor-type welding can be:

contact;
shock;
point.

During resistance welding, the energy accumulated in the tank is discharged into metal parts that were previously tightly connected to each other. An electric arc occurs at the place where the electrodes are pressed, at 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 exposure is 1.5 ms. This reduces the thermal impact on the surrounding area and improves the quality of the weld.

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 settings), and the metal bonding takes place in a small area.

Transformerless device

Having decided to make a device for capacitor welding on their own, they first choose a design option. 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 microfarads. In addition, you will need a high-voltage diode bridge for rectifying alternating current, a switch, electrodes with connecting wires.

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

DIY transformer circuit

When using a transformer circuit, a step-up transformer and a diode bridge for charging at 1 kV, 1000 microfarad capacitors and a step-down transformer are required, 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. In the secondary winding, an EMF is induced, which causes huge currents with closed electrodes on the workpieces to be connected.

The quality of welding will greatly depend on the condition of the electrode block. The simplest option is clamps for fixing and pressing 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 bar with a diameter of 8 mm and a length of 10-20 mm fixed to any base.

The upper part of the rod is rounded to obtain reliable contact with the metal to be welded. A similar copper rod is mounted on a lever, when lowered, the electrodes must be tightly connected. The base with the lower electrode is isolated 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 20 mm2 wire. A core Ш 40 with a thickness of 70 mm can be used as a magnetic circuit. To control the charge / discharge, a PTL-50 or KU202 thyristor is used.

Part preparation

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

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

Metal is welded at the point of contact between the electrodes. It is necessary to open the electrodes after some time, which is necessary for cooling and crystallization of the place of welding 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 welding spot should be 2-3 times 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 used. One electrode is attached to the thick part to be welded in any convenient place using a clamp.

In the place where you need to weld a thin part, it is pressed manually with a second electrode. You can use car clips. Then welding takes place. As you can see, the process is not too complicated, and affordable for home conditions.

Items that will be needed:

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

The difference between the spot welding method and other existing ones

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

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

Capacitor welding has the following advantages:

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

Energy charges will accumulate when charging from a generator or rectifier. You can adjust the energy 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:

1000 uF devices will store energy up to 1000 V by step-up transformer, while welding time will be 0.005 s. The welding current is in the range from 10 to 100 A. This method is dangerous for humans due to high voltage.
40000-400000 uF devices will store energy for voltages up to 60 V by means of a step-down transformer. Welding time can reach 0.6s. while 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 charge of energy to the primary winding of the transformer device.

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

Welding of non-ferrous metals by spot welding

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.

Capacitor Welding Technology

Heating time and pressure force

Features of the choice and use of electrodes

Factors on which the quality of welding depends:

The quality of welding will depend on the correct choice of the diameter of the copper electrode. The diameter of the connection point must necessarily exceed the thickness of the thin element of the welding connection by several times.
By pressing the workpieces at the moment of passage of the welding pulse, the appearance of a belt for sealing near the molten core can be ensured. As a result, no additional security measures are required at the connection point.
In order to be able to improve the crystallization of the molten workpiece, the electrodes will need to be opened with a slight delay after the passage of the welding pulse.
In order to be able to obtain a high-quality and reliable welding seam, the bases to be joined will need to be prepared first. In this case, we mean cleaning the elements from rust.
The distance between connection points should ensure that current shunting through nearby 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.

To reduce the wear of the electrodes, during use it is necessary to cool them intensively with water.

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

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

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

Aluminum electrolytic capacitors are one of the main elements that ensure the stability of the high-frequency inverter welding machines. Reliable high-quality capacitors for this type of application are produced by companies,.

The first devices using the arc welding method used adjustable AC transformers. Transformer welding machines are the most popular and are used to this day. They are reliable, easy to maintain, but have a number of disadvantages: high weight, high content of non-ferrous metals in the transformer windings, low degree of automation of the welding process. It is possible to overcome these shortcomings by switching to higher current frequencies and reducing the size of the output transformer. The idea to reduce the size of the transformer by switching from the mains frequency of 50 Hz to a higher frequency was born back in the 40s of the XX century. Then it was done with the help of electromagnetic transducers-vibrators. In 1950, for these purposes began to use vacuum tubes - thyratrons. However, it was undesirable to use them in welding technology due to low efficiency and low reliability. The widespread introduction of semiconductor devices in the early 60s led to the active development of welding inverters, first on a thyristor basis, and then on a transistor one. Insulated gate bipolar transistors (IGBTs) developed at the beginning of the 21st century gave a new impetus to the development of inverter devices. They can operate at ultrasonic frequencies, which can significantly reduce the size of the transformer and the weight of the apparatus as a whole.

Simplified block diagram of the inverter can be represented from three blocks (Figure 1). At the input there is a transformerless rectifier with a capacitance connected in parallel, which makes it possible to raise the DC voltage to 300 V. The inverter unit converts the DC into a high-frequency alternating current. The conversion frequency reaches tens of kilohertz. The unit includes a high-frequency pulse transformer, in which the voltage is reduced. This block can be manufactured in two versions - using single-cycle or two-cycle pulses. In both cases, the transistor block operates in a key mode with the ability to adjust the turn-on time, which allows you to adjust the load current. The output rectifier unit converts the alternating current after the inverter into welding direct current.

The principle of operation of the welding inverter is to gradually convert the mains voltage. First, the mains AC voltage is increased and rectified in the preliminary rectifier unit. The DC voltage powers the high frequency IGBT generator in the inverter unit. The high-frequency alternating voltage is converted to a lower one by means of a transformer and fed to the output rectifier unit. From the rectifier output, current can already be supplied to the welding electrode. The electrode current is controlled by circuitry by controlling the depth of negative feedback. With the development of microprocessor technology, the production of inverter semiautomatic devices began, capable of independently choosing the operating mode and performing such functions as anti-sticking, high-frequency arc excitation, arc retention, and others.

Aluminum electrolytic capacitors in welding inverters

The main components of welding inverters are semiconductor components, a step-down transformer and capacitors. Today, the quality of semiconductor components is so high that if they are used correctly, there are no problems. Due to the fact that the device operates at high frequencies and sufficiently high currents, special attention should be paid to the stability of the device - the quality of the welding work directly depends on it. The most critical components in this context are electrolytic capacitors, the quality of which greatly affects the reliability of the device and the level of interference introduced into the electrical network.

The most common are aluminum electrolytic capacitors. They are best suited for use in the primary source of a network IP. Electrolytic capacitors have a high capacitance, high voltage rating, small size, and are capable of operating at audio frequencies. Such characteristics are among the undoubted advantages of aluminum electrolytes.

All aluminum electrolytic capacitors are layers of aluminum foil (capacitor anode), paper spacer, another layer of aluminum foil (capacitor cathode), and another layer of paper. All this is rolled up and placed in a sealed container. Conductors are removed from the anode and cathode layers for inclusion in the circuit. Also, aluminum layers are additionally pickled in order to increase their surface area and, accordingly, the capacitance of the capacitor. At the same time, the capacitance of high-voltage capacitors increases by about 20 times, and low-voltage - by 100. In addition, this entire structure is treated with chemicals to achieve the required parameters.

Electrolytic capacitors have a rather complicated structure, which makes them difficult to manufacture and operate. The characteristics of capacitors can vary greatly under different operating modes and climatic operating conditions. With increasing frequency and temperature, the capacitance of the capacitor and ESR decrease. As the temperature drops, the capacitance also drops, and the ESR can increase up to 100 times, which, in turn, reduces the maximum allowable ripple current of the capacitor. The reliability of pulse and input network filter capacitors, first of all, depends on their maximum allowable ripple current. The flowing ripple currents are capable of heating the capacitor, which causes its early failure.

In inverters, the main purpose of electrolytic capacitors is to increase the voltage in the input rectifier and smooth out possible ripples.

Significant problems in the operation of inverters are created by high currents through transistors, high requirements for the shape of control pulses, which implies the use of powerful drivers to control power switches, high requirements for the installation of power circuits, and high pulse currents. All this largely depends on the quality factor of the input filter capacitors, therefore, for inverter welding machines, it is necessary to carefully select the parameters of electrolytic capacitors. Thus, in the preliminary rectification unit of the welding inverter, the most critical element is the filtering electrolytic capacitor installed after the diode bridge. It is recommended to install the capacitor in close proximity to the IGBT and diodes, which will eliminate the influence of the inductance of the wires connecting the device to the power supply on the operation of the inverter. Also, the installation of capacitors near consumers reduces the internal resistance to alternating current of the power supply, which prevents the excitation of amplifying stages.

Typically, the filter capacitor in full-wave converters is chosen so that the rectified voltage ripple does not exceed 5 ... 10 V. It should also be borne in mind that the voltage on the filter capacitors will be 1.41 times higher than at the output of the diode bridge. Thus, if after the diode bridge we get 220 V ripple voltage, then the capacitors will already have 310 V DC voltage. Usually, the operating voltage in the network is limited to 250 V, therefore, the voltage at the filter output will be 350 V. In rare cases, the mains voltage can rise even higher, so capacitors should be selected for an operating voltage of at least 400 V. Capacitors may have additional heating due to large operating currents. The recommended upper temperature range is at least 85…105°C. Input capacitors for smoothing rectified voltage ripples are selected with a capacity of 470 ... 2500 μF, depending on the power of the device. With a constant gap in the resonant choke, an increase in the capacitance of the input capacitor proportionally increases the power delivered to the arc.

There are capacities on sale, for example, at 1500 and 2200 microfarads, but, as a rule, a capacitor bank is used instead of one - several components of the same capacity connected in parallel. Paralleling reduces internal resistance and inductance, which improves voltage filtering. Also, at the beginning of the charge, a very large charging current flows through the capacitors, close to the short-circuit current. Parallel connection allows you to reduce the current flowing through each capacitor individually, which increases the service life.

Choice of electrolytes from Hitachi, Samwha, Yageo

In the electronics market today you can find a large number of suitable capacitors from well-known and little-known manufacturers. When choosing equipment, one should not forget that with similar parameters, capacitors differ greatly in quality and reliability. The most well-proven products from such world-famous manufacturers of high-quality aluminum capacitors as, and. Companies are actively developing new technologies for the production of capacitors, so their products have better characteristics than competitors' products.

Aluminum electrolytic capacitors are available in several form factors:

for PCB mounting;
with reinforced snap-in terminals (Snap-In);
with screw terminals (Screw Terminal).

Tables 1, 2 and 3 show the most optimal series of the above manufacturers for use in the pre-rectifier, and their appearance is shown in figures 2, 3 and 4, respectively. The given series have the maximum service life (within the family of a particular manufacturer) and an extended temperature range.

Table 1 Yageo Electrolytic Capacitors

Table 2. Samwha Electrolytic Capacitors

Table 3. Hitachi Electrolytic Capacitors

Name	Capacitance, uF	Voltage, V	Ripple current, A	Dimensions, mm	Form factor	Service life, h/°C
	470…2100	400, 420, 450, 500	2,75…9,58	30×40, 35×35…40×110	Snap-in	6000/85
	470…1500	400, 420, 450, 500	2,17…4,32	35×45, 40×41…40×101	Snap-in	6000/105
	470…1000	400, 420, 450, 500	1,92…3,48	35×40, 30×50…35×80	Snap-in	12000/105
	1000…12000	400, 450	4,5…29,7	51×75…90×236	screw terminal	12000/105
GXR	2700…11000	400, 450	8,3…34,2	64×100…90×178	screw terminal	12000/105

As can be seen from tables 1, 2 and 3, the product range is quite wide, and the user has the opportunity to assemble a capacitor bank, the parameters of which will fully meet the requirements of the future welding inverter. The most reliable are Hitachi capacitors with a guaranteed service life of up to 12,000 hours, while competitors have this parameter up to 10,000 hours in Samwha JY series capacitors and up to 5,000 hours in Yageo LC, NF, NH capacitors. True, this parameter does not indicate a guaranteed failure of the capacitor after the specified line has elapsed. This refers only to the time of use at maximum load and temperature. When used in a smaller temperature range, the service life will increase accordingly. After the specified line, it is also possible to reduce the capacity by 10% and increase losses by 10 ... 13% when operating at maximum temperature.

Advantages and disadvantages of technology

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 release;
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.

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.

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.
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.
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:

Capacitor spot welding is mainly used to connect parts with different thickness ratios. It is successfully used in the field of electronics and instrumentation.
Roller welding is a certain number of spot joints made in the form of a continuous seam. The electrodes are like rotating coils.
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.

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

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

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.

Contact block device

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.

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.
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.
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

Surely, when working with batteries to replace them, you needed contact welding. Since it is very undesirable to solder lithium-ion batteries with ordinary solder, there is a danger of overheating. Buying or making expensive equipment for two or three cases is definitely not profitable and costly. But such a device for resistance welding is available to absolutely everyone. After all, it essentially consists of just one part, called a supercapacitor.
This is almost the same capacitor, only high capacitance. Having all the same advantages as a conventional capacitor.

It will take

Thick wire, with a cross section of at least 2 square meters. mm.

Manufacturing of the simplest apparatus for resistance welding from a supercapacitor

We unwind the coil with wire and cut off two identical pieces 5-7 cm long.

We straighten them with wire cutters or pliers so that they are very even. Now, on one side of each segment, we clean the edge with a file, removing the varnish insulation.

And on the other hand, we make a point.

Ludim ionistor contacts.

We grind the bare and blunt ends of the pieces of copper wire.

Solder the segments to the contacts of the supercapacitor.

The contact welding machine is completely ready!

It remains only to bend the output with wire cutters so that there is a minimum distance between the tip of 2-3 mm.

We charge with a current of 5 A.

The voltage should not exceed 2.7 V. Although, as you can see in the photo, I have one tenth more. It's certainly not critical, but it's better not to risk it.

Charging took about 15 minutes.

contact welding

Now let's figure out how to weld. Since our apparatus is impossibly simple, it cannot regulate the length of the pulses. The whole task thus falls on you. Therefore, exposure will have to be done intuitively.
Here is an example of how to solder a metal strip to a battery. I put a strip on the battery. Now we bring the contacts of the device and thereby quickly close it.

We hold it for about 0.5 seconds and quickly remove it so as not to burn the connection.