How to make a spot welding machine with your own hands. Resistance welding - how to make equipment and pliers yourself? Spot welding using a welding inverter

Inverters on the market are presented in a huge range, so everyone, if necessary, can choose the most suitable equipment for carrying out welding work at home. An alternative to this choice is resistance welding from an inverter.

Below you will find out what resistance welding is, how to make a device based on a microwave or battery, as well as how to use it correctly.

Everyone may need to do welding work at home during renovations. An inverter may be useful for installation metal parts or in a mini-workshop at home.

The operating principle of the inverter is as follows:

• the metal is heated by electric current;
• it then melts and solidifies after forming a weld;
• To secure the parts and protect them from moving apart, the parts are compressed by electrodes through which current flows.

To carry out home welding work, you need a powerful power source, and this can lead to to overheating of household wires. Check the quality of your wiring in advance and replace it if necessary.

During spot welding, you need to connect two workpieces along adjacent edges. This will be required when installing small parts made of thin material, in particular, metal rods up to 0.5 cm thick.

Connection options

When resistance welding, surfaces can be joined in the following ways:

• continuous reflow;
• intermittent;
• resistance.

When working using melting, you need to connect parts or sheets of metal or heat them with current until melting occurs. This technology relevant for the following types of work:

• processing of non-ferrous metal or low-carbon steel;
• installation of copper, steel or brass.

However, this method is not particularly popular due to the fact that there are strict temperature requirements, and also because there should be no impurities.

During continuous melting of workpieces You will need welding pliers and other fasteners. The parts are connected when the current is on. When the edges of the parts melt, precipitation will occur, and the current landing will turn off. Thin-walled pipelines are installed in this way, but it is also possible to connect workpieces that differ in structure. The key advantage of the method is efficiency. But there is a risk that metal will leak out along the welding seam and cause waste.

Intermittent reflow is performed with sequential tight or loose contact. Using clamping pliers, the welding line is closed in the area where the workpieces are joined so that the temperature rises to 900-950 degrees. This method used when the initial power of the device for continuous reflow is insufficient.

Resistance welding solves the following problems:

• the surface for installation is prepared (the contours are cleaned and leveled);
• the edges of the workpieces are connected and secured with clamping parts;
• turns on the current source;
• the edges of the workpieces heat up and melt when the device is running;
• upsetting is performed and the current is turned on.

These types welding processes in technology they differ little from each other, but they differ in the current supply and fastening of parts.

To weld parts using the spot method for household needs, the device can be made independently. Its key mechanisms are:

• clamp;
• device for supplying voltage to capacitors. In it, an electrode is attached to the low-voltage winding.

The second clamping wing is a support wing and can be mounted with large parts.

DIY microwave equipment

You can make a device for carrying out welding work using the contact method with your own hands; the key part in it is This is a microwave transformer.

To make such a device, you will need to perform preliminary calculations profitability of this device compared to buying a ready-made inverter.

For a homemade device, the most expensive part is the transformer, but Consumables(such as a base for fastening parts or a casing with wires) can be obtained from the service center.

Transformer with power from 1 kW Suitable for the manufacture of welding equipment for joining sheets up to 1 mm thick. If its power is twice as large, then it will be suitable for processing sheets up to 1.8 mm thick. Many microwave ovens are equipped with a 3 kW transformer.

To increase the current capacity, 2 or 3 transformers may be required. The transformer itself is pulled out of the protective casing, the shunts are removed along with the secondary winding. Since in microwave oven the voltage is high, there are fewer loops on the primary winding of the device compared to the secondary. In order to remove the potential difference, the secondary winding is removed and adapted to work with spot welding.

The work looks like this:

The outputs of the secondary windings are combined when using a circuit based on several transformers. And if you use one transformer, you can reduce the microwave body in width and length.

For several transformers, the casing is made on the basis of an iron sheet, which is covered with electrical tape.

To supply current to the area to be welded you need to create a lever device. One lever is firmly attached to the main surface, and while lowering, the second will put pressure on the workpiece.

Insert the switch into the primary winding circuit and install it on the upper lever, thanks to this it will be possible to start current and compress the part at the same time. In this case, pliers will not be needed; you will need to solder the tips to the wiring in advance in order to prevent oxidation.

For resistance welding, copper rods with a thickness greater than the size of the wiring are used, which will be replaced or sharpened during operation. During operation, the part will be clamped between the electrodes by levers, then the current will start.

Battery welding machine

When welding using electrical equipment household networks are under enormous pressure. As a result of long spot welding, wires may melt or household equipment may break. Accordingly, the device can be powered from autonomous source. For example, a portable generator that runs on gasoline or diesel fuel. You can purchase such a generator or make it yourself.

You will need several batteries from used cars. IN in this case The current calculation will be 1/10 of the battery capacity. When using batteries of different power, the calculation can be done using the smallest capacity.

You will need to create a circuit of batteries connected in series. The “pros” and “cons” are fastened with wire cutters, wires or wiring for the cigarette lighter, or any pliers. The wire is brought out from the free “minus” to the electrode and clamped with pliers. A rheostat is placed in the circuit from the free “plus” towards the working plate.

When the equipment is ready, additional charging equipment can be made.

Features of a homemade welding machine

Resistance welding in technological terms not too complicated, but to achieve required quality connections, you need to manage it correctly. That's why homemade device based on a microwave oven will need to be equipped with special controls. The key ones are the lever, the switch, as well as the lever through which the compression force is exerted on the electrodes and the parts that are connected.

The quality of the connection directly depends on the compression force; accordingly, the lever for the device should be as long as possible. It is important that the welding equipment can be securely fixed to the surface of the work table using clamps.

The force transmitted by the electrodes can be increased not only with a lever, but also with a lever-screw mechanism, which can also be attached to a homemade device. It is best to attach it directly to the lever so that manipulations are quick. This placement will also free up your other hand so you can support the parts.

Features of working with a spot welding machine is that current can be applied to the electrodes only when they are compressed. And if the current supply is turned on before compression, the electrodes will spark when they come into contact with parts, which will lead to burning and failure.

The switch for controlling welding will need to be placed in the primary winding circuit. And if it is installed in the circuit of the secondary winding, through which a significant current passes, then additional resistance will be created, and as a result the electrodes will be welded to each other.

Also homemade apparatus based on a microwave oven, you will need to equip it with a simple cooling system, which you can also make yourself. For such a system, you can take a regular fan, with which you can cool the electrodes, transformer, and other conductive elements. Naturally, this cooling is not very effective, and you will need to take regular breaks so that all the heating elements of the equipment can cool down on their own.

We discussed above Features of assembling equipment for spot welding with your own hands. This method is available to everyone, since the materials for the work are not too expensive, and spot welding skills can be mastered very quickly.

Quite often there is a need to carry out welding work at home. As a rule, these are small volumes performed occasionally. Since factory-made welding machines are very expensive, many craftsmen prefer to make them different ways from scrap materials. A good option for a factory analogue is considered to be do-it-yourself contact welding from an inverter, which ensures high quality work at a relatively low cost.

The device and principle of operation of contact welding

The operating principle of any point welding machine consists in heating metal parts in certain places with an electric current, their subsequent melting, mixing with each other and solidifying. As a result, a weld seam is formed in the places where both metals solidify. During operation, both parts are reliably compressed and fixed by electrodes to which electric current is supplied.

Performing resistance welding at home will require powerful power sources, which can lead to overheating and failure of household electrical wiring. In this regard, it is recommended to check the condition of the wiring in advance and replace it if necessary.

When performing spot welding, two workpieces are connected to each other along adjacent edges. This method is very effective for working with small parts, thin metal sheets and rods with a diameter of up to 5 mm.

Surfaces are connected in one of three ways:

• When using the reflow method, all parts to be welded are joined and heated by electric current until they melt. This technology is widely used in working with non-ferrous metals, low-carbon steels, brass and copper workpieces. In other areas, this method is used extremely rarely due to high temperature requirements and the absence of impurities at the joints. Homemade resistance welding from a welding machine works in exactly the same way.
• Continuous welding of workpieces using the reflow method is performed using welding tongs. The connection of parts occurs at the moment the current is turned on. After the edges of the mounted parts have melted, they are upset and the current supply is stopped. Thin-walled pipelines and workpieces with different structures are welded using this method. The main disadvantage of this method is the likelihood of metal leaking out of the weld and the appearance of carbon monoxide.
• The third method is intermittent melting, which ensures alternately tight or loose contact between the workpieces. The welding line is closed in the joint area with clamping pliers until their temperature rises to 950 degrees. This method is used if the power welding device initially insufficient to perform continuous reflow.

Preparing parts and assembling spot welding

The standard design of a resistance welding machine consists of a power section, a circuit breaker and protective device. In turn, the power part includes a welding transformer and a thyristor starter, with the help of which the primary winding is connected. The entire inverter is not needed for a homemade welding machine; you only need to take the main parts from it. This is a transformer with a power supply, a control system and a switch.

When making spot welding, first of all, you need to remove the secondary winding from the transformer, since it is not used at all during operation. The main thing when removing the winding is to keep the primary winding intact. Instead of the removed secondary winding, another one is placed, made of thick copper wire, with a cross-section of approximately 2-3 cm. Then it is wrapped in insulating paper and varnished for additional insulation and fixation.

The direction of each winding is then checked using a conventional voltmeter. There should be no short circuits in the newly created circuit. After this, the current strength is determined. This procedure is mandatory for all such devices with two or more windings. The current value should not be more than 2 kiloamperes. If the set level is exceeded, it must be reduced.

When preparing the transformer coil and winding the secondary winding, it is recommended to follow the mandatory rules. To calculate the number of turns, you can use the formula N = 50/S, in which N is the number of turns, and S is the core area (cm2). It will help speed up calculations. Since the design uses parts from the inverter, the parameters of the primary coil are first determined, the necessary calculations are made, and only then the secondary winding can be manufactured.

Pay attention to the grounding of both windings. This is due to the high power of the current received, which can be fatal if it comes into contact with live parts. Along with careful insulation, great importance has a dense laying of turns. Otherwise, interturn short circuits may occur and the wires will burn out as a result of overheating. It is also necessary to take care of cooling the transformer. It may be necessary to install additional system cooling, which includes radiators blown by fans.

Additional elements of the welding machine

The next step after manufacturing the transformer will be the manufacture of contact clamps. The quality of their manufacture largely determines how resistance welding from an inverter will work. The design of the pliers is selected depending on the specifics of future welding work. The gripping device is manufactured in accordance with the drive system and the dimensions of the parts to be connected.

The most important part of the pliers is the contact tips. You can use copper tips from a soldering iron or purchase ready-made products. It should also be taken into account that they should not melt during operation, so a refractory metal should be used for their manufacture. Typically rods with a diameter of about 15 mm are used. The diameter of the connected cable is always less than the diameter of the lugs.

The wires are connected to the electrodes using ordinary copper lugs. Direct connection is carried out by bolts or soldering, which significantly reduces the likelihood of oxidation at the contact points. Soldering is most often used in low-power devices, eliminating incorrect connections that cause current disturbances at the output of the device.

The main advantage of bolted connections is the ability to quickly replace failed parts without additional soldering work. All bolts and nuts must be copper. If it is intended to apply connecting seams over a long distance, in this case the tips are equipped with special rollers.

After manufacturing the pliers, the time comes to solve an equally difficult task - ensuring the necessary pressure of the electrodes at the point of welding the parts. The main difficulty lies in the fact that it is impossible to create high and uniform pressure manually. If other options are not considered, then it is best to initially refuse to make spot welding from an inverter, because the efficiency of such a device will be extremely low.

In industry, this problem is successfully solved by using amplifiers based on pneumatic or hydraulic systems. It is almost impossible to make such devices at home. For homemade spot welding, the best option is a compressed air system driven by a conventional pneumatic compressor. The most optimal maximum indicator required for normal operation, there will be a force at the ends of the electrodes of 100 kg or more. Pressure changes using a separate regulator, which can be built into common system management.

At the final stage of assembling resistance welding from the inverter, all that remains is to mount the entire system. For installation, it is recommended to use ready-made elements, which significantly simplifies assembly and improves performance characteristics. All the missing parts are in the inverter, from which the transformer was already taken.

The capacity of the capacitors installed in the inverter may not be sufficient for normal operation. Therefore, if necessary, they are replaced with other parts that are most suitable in their parameters. Next, stepwise current adjustment is performed, the accuracy of which is affected by specifications secondary winding. By making such adjustments, it is possible to create equipment capable of operating in different modes.

When repairing a car or construction work often there is a need for a resistance welding machine, which one would like to have, but it high price does not allow you to make such a purchase. We will tell you how to make such a unit from a welding machine inverter type on your own. A contact type connection is based on pressure and heating of the metal using welding current with a short-term effect on the parts being welded. Industrial devices of this kind have been widely used for a long time; we will tell you how to assemble such a device from an inverter at home.

Many types of equipment are due to their high efficiency, economy and speed of operation. Some of them have high-tech control over the quality of work, can evaluate the thickness and parameters of the metal and regulate the current process. The resistance welding machine of the Car-o-Liner CTR 41977 line performs all types of high-precision metal work and is a source of powerful welding current.

Swedish Car-o-liner units allow you to weld sheet metal, and are built on an inverter technological basis. Car-o-Liner devices allow welding of metal under point pressure, and are designed, among other things, for car body repairs.

• Besides? There are other, much simpler, equipment for joining in the contact zone of sheets; such an example is the TOP resistance welding machine, which has the following parameters:
• low weight (8 kg) and power (2 kW);
• welds sheet metal up to 2 mm thick;
• it is possible to weld rods up to 4 mm;
• carries out heating of the metal for the purpose of subsequent processing; there is a soldering function with high temperature
• melting;
• The set includes carbide shaped and straight electrodes;

there are specialized pliers with a hose of more than 2 m;

The use of such contact welding machines with an affordable price and high mobility allows you to carry out minor home and body repairs, as well as weld reinforcing mesh during construction work.

It is important to note that the low voltage at the terminals allows work to be carried out in compliance with safety regulations.

The metal-friendly properties of resistance welding machines allow them to be used in bodywork and other sheet metal repairs as a spotter. It should be discussed in more detail because most people experience damage to the car body. We're talking about dents that need to be pulled out and straightened out. In this case, special copper electrodes are used, which, after cleaning the body parts, are spot welded to the dent. Then, with their help, the irregularities are pulled out by additional heating and cooling of the metal. This one is very effective method

repair allows you to pull out irregularities even in hard-to-reach places.

To assemble a resistance welding machine with your own hands, you need to determine in advance how you want to use it. The light weight of the inverter unit, which we will take as the basis of the kit, allows us to assemble both a mobile and stationary version. The fact is that the pliers, which provide the necessary pressure at the welding point, can be mounted on a stationary platform or on a flexible hose.

Fixed electrodes are more suitable for in-line welding sheet metal, while the mobile option is more versatile.

Separately, you need to consider the selection criteria welding inverter, as a current source for the contact method of operation. It must have a wide range of current and voltage adjustments, and since the output waveform is pulsed, this parameter must also be adjustable. Thus, the AKS resistance welding machine must be equipped with refractory electrodes, which can be mounted in the following options, namely:

1. stationary option, in which the sheets to be welded are placed on a stationary negative electrode and are pinpoint pressed with the positive electrode;
2. mobile version using pliers that allow squeezing the parts to be joined at the welding point;
3. option using a welding gun as a positive electrode, where the minus is the body part.

The use of a gun is typical for the work of a spotter during body repair, and in this case, replaceable copper tips are used, which make it possible to straighten defective areas. To save money, you can make a welding gun or pliers with your own hands, both in a stationary and mobile version. To do this you will need the following materials and tools:

• textolite for a gun or pliers;
• start button;
• fastening bolts with nuts;
• copper or bronze tip as an electrode;
• connecting cables and wires;
• mini-socket with a light bulb for illumination;
• jigsaw, grinder and electric drill;
• powerful electric soldering iron;
• marking devices;
• set of screwdrivers and wrenches.

It is important to ensure reliable contact of the welding cable with the tip holder or replacement tips to avoid overheating and power loss.

It is necessary to consider quickly changing bronze or copper electrodes or tips, since operating conditions may change, and when repairing sheet metal of a car body, replacement is part of the technological process.

Assembly of the resistance welding kit and sequence of work

When carrying out resistance welding with your own hands, you need to understand that the whole process takes from 0.5 to 1.5 seconds, so the start button must be placed in an open circuit of the primary winding of the inverter. It is important to prevent burning through the metal, and for this it is necessary to adjust the high-frequency output voltage of the inverter in an optimal way and experimentally select the welding duration. When joining sheets with an overlap, it is necessary to ensure that they remain motionless relative to each other, and also to press the electrode to the welding point with constant force.

Final assembly involves connecting all components and checking for reliable, safe contact in the welding current circuit and the control button. Checking the functionality of the device and adjusting the output parameters consists of the following actions:

• setting the inverter to the minimum welding current;
• checking the reliability of the connection of the cable, gun or pliers, as well as the start button;
• short-term spot welding is carried out on test parts and, if necessary, the settings of the inverter output parameters are adjusted;
• welding is stopped and the result is evaluated; in the case of burning through the workpieces, the current and welding time at the point of contact are reduced;
• welding is considered correct when the workpieces are separated from each other along the metal, and not at the welding point;
• If the device is used as a spotter, it is necessary to ensure reliable welding of the tips to the surface of the area being repaired.

It is very important to ensure the safety of the worker in order to avoid possible electric shock and to carry out welding in special clothing that protects against burns.

Let's sum it up

We considered the possibility of assembling a resistance welding machine with our own hands using an inverter as a current source. This achieves significant cost savings with little investment of time and materials. The capabilities of such a resistance welding machine are quite sufficient for personal needs and car body repairs, as well as reliable connection of sheet metal. Good luck with your work.

Resistance welding, in addition to the technological advantages of its application, has another important advantage - simple equipment for it can be made independently, and its operation does not require specific skills and initial experience.

1 Principles of resistance welding design and assembly

Resistance welding, assembled with your own hands, can be used to solve a fairly wide range of non-serial and non-industrial problems in the repair and manufacture of products, mechanisms, equipment from various metals both at home and in small workshops.

Resistance welding ensures the creation of a welded joint between parts by heating the area of ​​their contact with an electric current passing through them while simultaneously applying a compressive force to the joint area. Depending on the material (its thermal conductivity) and the geometric dimensions of the parts, as well as the power of the equipment used for welding them, the resistance welding process should proceed under the following parameters:

• low voltage in the power welding circuit – 1–10 V;
• in a short time - from 0.01 seconds to several;
• high welding pulse current - most often from 1000 A or higher;
• small melting zone;
• the compressive force applied to the welding site must be significant - tens to hundreds of kilograms.

Compliance with all these characteristics directly affects the quality of the resulting welded joint. You can only make devices for yourself, as in the video. The easiest way to assemble an alternating current welding machine with unregulated power. In it, the process of joining parts is controlled by changing the duration of the supplied electrical pulse. To do this, use a time relay or cope with this task manually “by eye” using a switch.

Homemade spot contact welding is not very difficult to manufacture, and to perform its main component - welding transformer– you can pick up transformers from old microwave ovens, TVs, LATRs, inverters and the like. The windings of a suitable transformer will need to be rewound in accordance with the required voltage and welding current at its output.

The control circuit is selected ready-made or developed, and all other components, in particular for the contact welding mechanism, are taken based on the power and parameters of the welding transformer. The contact welding mechanism is manufactured in accordance with the nature of the upcoming welding work according to any of the known schemes. Welding pliers are usually used.

All electrical connections must be made efficiently and have good contact. And connections using wires are made from conductors with a cross-section corresponding to the current flowing through them (as shown in the video). This is especially true for the power part - between the transformer and the electrodes of the clamps. If the contacts of the latter circuit are poor, there will be large energy losses at the joints, sparking may occur, and welding may become impossible.

2 Diagram of a device for welding metal up to 1 mm thick

To connect parts using the contact method, you can assemble them according to the diagrams below. The proposed machine is designed for welding metals:

• sheets, the thickness of which is up to 1 mm;
• wires and rods with a diameter of up to 4 mm.

Main technical characteristics of the device:

• supply voltage – alternating 50 Hz, 220 V;
• output voltage (on the electrodes of the contact welding mechanism - on the pliers) - alternating 4–7 V (idle);
• welding current (maximum pulse) – up to 1500 A.

Figure 1 shows the principle electrical diagram the entire device. The proposed resistance welding consists of a power part, a control circuit and an automatic switch AB1, which serves to turn on the power supply to the device and protect it in the event of an emergency. emergency situations. The first unit includes a welding transformer T2 and a contactless thyristor single-phase starter of the MTT4K type, which connects the primary winding T2 to the supply network.

Figure 2 shows a diagram of the windings of a welding transformer indicating the number of turns. The primary winding has 6 terminals, by switching which you can make stepwise rough adjustment of the output welding current of the secondary winding. In this case, pin No. 1 remains permanently connected to the network circuit, and the remaining 5 are used for adjustment, and only one of them is connected to power for operation.

Diagram of the MTT4K starter, produced in series, in Fig. 3. This module is a thyristor switch, which, when its contacts 5 and 4 are closed, switches the load through contacts 1 and 3, connected to the open circuit of the primary winding Tr2. MTT4K is designed for loads with a maximum voltage of up to 800 V and a current of up to 80 A. Such modules are produced in Zaporozhye at Element-Converter LLC.

The control circuit consists of:

• power supply;
• control circuits directly;
• relay K1.

The power supply can use any transformer with a power of no more than 20 W, designed to operate from a 220 V network and delivering a voltage of 20–25 V on the secondary winding. It is proposed to install a diode bridge of the KTs402 type as a rectifier, but any other with similar parameters or assembled from individual diodes.

Relay K1 serves to close contacts 4 and 5 of the MTT4K key. This occurs when voltage is applied from the control circuit to the winding of its coil. Since the switched current flowing through closed contacts 4 and 5 of the thyristor switch does not exceed 100 mA, almost any low-current electromagnetic relay with an operating voltage in the range of 15–20 V, for example, RES55, RES43, RES32 and the like, is suitable as K1.

3 Control circuit - what does it consist of and how does it work?

The control circuit performs the functions of a time relay. By turning on K1 for a given period of time, it sets the duration of exposure of the electrical pulse to the parts being welded. The control circuit consists of capacitors C1–C6, which must be electrolytic with a charging voltage of 50 V or higher, switches of the P2K type that have independent fixation, a button KH1 and two resistors - R1 and R2.

The capacitor capacity can be: 47 μF for C1 and C2, 100 μF for C3 and C4, 470 μF for C5 and C6. KN1 should have one normally closed and the other normally open contact. When AB1 is turned on, the capacitors connected via P2K to the control circuit and power supply (in Fig. 1, this is only C1) begin to charge; R1 limits the initial charging current, which allows you to significantly increase the service life of containers. Charging occurs through the normally closed contact group of the KN1 button, which was switched at that time.

When you press KH1, normally closed contact Group opens, disconnecting the control circuit from the power supply, and the normally open one closes, connecting the charged containers to relay K1. The capacitors are discharged, and the discharge current triggers K1.

The open normally closed contact group KH1 prevents the relay from being powered directly from the power supply. The greater the total capacity of the discharged capacitors, the longer they take to discharge, and, accordingly, K1 takes longer to close contacts 4 and 5 of the MTT4K switch, and the longer the welding pulse. When the capacitors are completely discharged, K1 will turn off and resistance welding will stop working. To prepare it for the next impulse, KH1 must be released. The capacitors are discharged through resistor R2, which should be variable and serves to more accurately regulate the duration of the welding pulse.

4 Power section - transformer

The proposed resistance welding can be assembled, as shown in the video, on the basis of a welding transformer made using a magnetic core from a 2.5 A transformer. These are found in LATRs, laboratory instruments and a number of other devices. The old winding must be removed. At the ends of the magnetic circuit it is necessary to install rings made of thin electrical cardboard.

They are folded along the inner and outer edges. Then the magnetic circuit must be wrapped over the rings with 3 or more layers of varnished cloth. Wires are used to make windings:

• For a primary 1.5 mm in diameter, it is better in fabric insulation - this will facilitate good impregnation of the winding with varnish;
• For a secondary with a diameter of 20 mm, multi-core in silicone insulation with a cross-sectional area of ​​at least 300 mm 2.

The number of turns is indicated in Fig. 2. Intermediate conclusions are drawn from the primary winding. After winding, it is impregnated with varnish EP370, KS521 or similar. A cotton tape (1 layer) is wound over the primary coil, which is also impregnated with varnish. Then the secondary winding is laid and impregnated with varnish again.

5 How to make pliers?

Resistance welding can be equipped with pliers, which are mounted directly into the device body itself, as in the video, or with remote ones in the form of scissors. The first ones, from the point of view of making high-quality, reliable insulation between their nodes and ensuring good contact in the circuit from the transformer to the electrodes, are much easier to manufacture and connect than remote ones.

However, the clamping force developed by such a design, if the length of the movable arm of the pliers after the electrode is not increased, will be equal to the force created directly by the welder. Remote pliers are more convenient to use - you can work at some distance from the device. And the force they develop will depend on the length of the handles. However, it will be necessary to make fairly good insulation from textolite bushings and washers at the place of their movable bolted connection.

When making pliers, you need to foresee in advance the necessary extension of their electrodes - the distance from the body of the device or the place of the movable connection of the handles to the electrodes. The maximum possible distance from the edge of the sheet part to the place where the welding is performed will depend on this parameter.

The clamp electrodes are made from copper or beryllium bronze rods. You can use the tips of powerful soldering irons. In any case, the diameter of the electrodes must be no less than that of the wires supplying current to them. To obtain welding cores of the required quality, the size of the contact pads (tips of the electrodes) should be as small as possible.

Home plumbing work is part of the life of a business person. One of the most popular home devices is spot welding. It assumes the presence of a factory or homemade welding device. It is not difficult to create a similar device that will be used for spot welding with your own hands; you only need desire and some available tools.

Features and principle of spot welding

Let's start studying the question of how to make spot welding with our own hands with the principle of operation.

Today, spot welding is in demand not only in everyday life, but also in production, as it can solve even the most difficult tasks. In industry, as a rule, devices operating in automatic mode are used in living conditions A semi-automatic welding machine is used for spot welding.

Spot resistance welding in production is necessary to weld sheet blanks from ferrous and non-ferrous metals. It is used to weld products from profiles of different thicknesses and configurations, as well as intersecting metal workpieces. Under some conditions, it is possible to achieve a high-speed operating mode of up to 600 points per minute.

Many people are interested in the question of how to make spot welding at home? In the home environment, spot welding is used to repair household utensils and, if necessary, to weld electrical wires.

The spot welding procedure includes several stages:

• the workpieces are combined in the required position;
• fasten the parts directly between the clamping electrodes of the installation;
• the surfaces are heated, during which the parts are deformed and they bond with each other.

There is another point connection technology - laser welding. It is capable of performing tasks involving high precision work and extreme soldering strength.

It turns out that the principle of spot welding is the excessive heating of working metal surfaces, which results in their fusion and a single structural new formation.

The main role in the welding process is played by the impulse response of the current, which creates the necessary heating of the metal area. An equally important characteristic is the exposure time and the holding force of the parts. Thanks to these parameters, the metal structure crystallizes.

The main advantages of electric contact welding from a welding machine are:

• profitability of use;
• strong seam;
• simplicity of equipment;
• homemade spot welding can be created at home;
• possibility of automation in an enterprise environment.

The only flaw in the point connection of parts is considered to be a leaky connection.

The main requirements for welding equipment are:

• the ability to change the process time;
• creating pressure in the working area, reaching the limit at the end of the heating process;
• the presence of electrodes with high energy and heat conductivity.

For household use, electrolytic copper and its mixture of EV grade are suitable. It is worth noting that the area of ​​the contacted area of ​​the electrode must exceed the joint (seam) to be welded by 2.5 times.

Assembling a welding machine yourself

To spot weld parts, it is necessary to create appropriate equipment. A homemade do-it-yourself spot welding installation can have any shape - from portable varieties to large-sized models. In practice they are usually used desktop options, used for joining various metals. Before you create spot welding from an inverter, you should familiarize yourself with the materials that will be needed during manufacture.

• energy converter, that is, a transformer;
• electrical cable with insulation with a cross-section of 10 mm;
• copper electrodes;
• breaker;
• tips;
• bolts;
• available tools and materials for creating a frame base or welding pliers (blocks of wood, recycled materials, plywood).

1 - modified OSM-1.0 transformer; 2 - conductor (duralumin rod with a diameter of 30, L300, 2 pcs.); 3 - liner (steel rod with a diameter of 10, L30, 2 pcs.); 4 - electrode (copper rod with a diameter of 12, L50, 2 pcs.); 5 - brass washer (2 pcs.); 6.12 - M6 screws; 7 handle; 8 - eccentric; 9 - cheek (2 pcs.); 10 - spring; 11 - output of half of the secondary winding (4 pcs.); 13 - textolite bushing (with a groove for the end loop of the spring); 14 - M8 bolt (6 pcs.); 15 - textolite washer (4 pcs.); 16 - insulating coating (varnished fabric or protective adhesive tape on a fabric basis, 2 pcs.); 17 - transformer casing.

Installation diagrams

The main types of welding device assembly schemes are simple projects with a minimum amount of required materials. It is worth noting that the manufactured equipment will not be powerful, that is, this spot welding scheme is intended only for domestic use. Its purpose is to weld small sheets of iron and electrical wires.

To understand how to do resistance welding, remember the school curriculum, namely the physical rule “Joule-Lenz Law”: when electricity passes through a conductor, the amount of thermal energy created in it is directly proportional to the resistance of the conductor, the time of exposure and the square of the electric current. Conclusion, if the current was initially large (for example, 1000 A), then with a weak connection and small wires it will be consumed large quantity energy (several thousand times) than with a lower electric current (10 A). That is, the quality of the collected electrical circuit plays an important role.

The formation of an electrical pulse between two sections of metal products is considered a basic part of the operation of a welding installation. This will require a small energy converter. The product to be welded must be connected to the lower winding of the device, and the metal electrode to the secondary.

It is worth noting that It is unacceptable to directly combine the converter with the power source. For this purpose, a bridge with an electronic switch (thyristor) is provided in the electrical circuit. To create the required pulse, the device must be supplied with auxiliary power, which includes an energy rectification bridge and a transformer. Electricity will be concentrated in a capacitor, whose role is to form a pulse.

In order for a home-made resistance welding machine to work, you need to press the “pulse button” on the handle of the gun to open the capacitor-resistor circuit diagram. As a result of these manipulations, a discharge will occur through the metal rod. To reinforce the theoretical material, it is recommended to watch the training video, which explains in detail about spot welding. This allows you to visually understand how this is all done correctly.

Homemade device from a microwave oven

Since it is not always possible to allocate an extra amount of money for spot welding machines, you can make it yourself. This will require a fairly powerful microwave oven.

Transformer assembly

You only need one part from the microwave - a high-voltage transformer for spot welding. This part requires only a core (magnetistor) and a primary (lower) winding. To remove unnecessary areas, you can use a hammer, grinder or hacksaw. After removing the transformer secondary winding, it is necessary to create a homemade transformer for resistance welding. To do this, you should use a copper cable with a diameter equal to the opening of the transformer. It is necessary to make two turns. In order to connect the two parts of the core you will need epoxy resin.

The base is done, now we need to work on the body homemade installation. For this purpose, various polymers are used, for example, plastic or wood. The back area of ​​the point installation housing should contain several openings. One opening will serve as the key for the device, and the other will supply electricity.

If wood is used instead of plastic, then first you should perform several preparatory operations, namely sanding, impregnation and varnishing. To create a homemade working machine for spot welding with your own hands, you will need:

• power supply cable for the welding unit;
• Door knob;
• switch;
• copper holders;
• large diameter electrical wire;
• consumables (screws, nails).

After the body section has dried, it is necessary to assemble the installation and combine all the associated parts. After this, the copper wire is cut into 2 parts, each of which is approximately 25 mm. These elements will perform the function of electrodes. To fix them, just use a standard screwdriver. Then you need to install the system key; a thick electrical cable will prevent it from slipping out. To fix the transformer to the structure body, you can use self-tapping screws, but do not forget about grounding one of the terminals.

To increase the safety of using the welding device, it is recommended to install an auxiliary switch. Small nails and other fasteners are also used to secure the working arms. Contact metal rods are attached to the end parts of the handles. To raise the upper handle, a standard polymer is used - rubber.

Creating Electrodes

Elements used for do-it-yourself spot welding must meet certain requirements, namely resistance to operating temperatures, good electrical conductivity and ease of machining.

Copper wires with a cross-section of 15 mm or more are perfect for this. The basic principle is that the cross-section of the electrode should not be less than the diameter of the wire. If you don’t mind, you can use the tips of 2 soldering irons, which will definitely last a long time.

Controls

The do-it-yourself resistance welding has a simple device. There are only two control systems - a switch and a handle. The spot welding switch is fixed in the primary winding circuit. This is necessary because there is more current in the secondary winding, and the switching system will create additional resistance. The switch is installed on the lever, so it will be more convenient to work. That is, you can turn on the electricity with one hand, and hold the materials being welded with the other.

It is worth noting that turning on and off the welding current must be done only with compressed electrodes, because otherwise a spark will appear, leading to their burning. It is also recommended to use a fan to cool the device.

If such a cooling system is not available, then the temperature of the energy converter, metal electrodes, electrical wires should be constantly monitored and additional breaks should be created to prevent overheating.

Today, purchasing a welding machine for spot welding is not a problem if you have cash. Any specialized store will offer a range of installations for point joining of parts, with different capacities and manufacturers. But for home craftsmen it is not always possible to select the required parameters, so making a spot welding machine with your own hands will be the optimal solution. All necessary supplies can be borrowed and found at home. Collected with my own hands The spot welding installation does not fail and works perfectly, thereby providing the required minor repairs metal products.