Making spot welding from an inverter. Making spot welding from an inverter Do-it-yourself spot welding from an inverter

Content:

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

The device and principle of contact welding

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

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 bars, up to 5 mm in diameter.

Surface joining is done in one of three ways:

In the fusion method, all parts to be welded are connected and heated by an electric current until they melt. This technology is widely used in working with non-ferrous metals, low-carbon steels, brass and copper blanks. In other areas, this method is used extremely rarely due to high requirements for temperature conditions and the absence of impurities at the joints. Homemade resistance welding from a welding machine works in the same way.
Continuous welding of workpieces by the flash method is carried out using welding tongs. The parts are connected at the moment the current is turned on. After the edges of the mounted parts are melted, they are upset, and the current supply is stopped. In this way, thin-walled pipelines and workpieces with different structures are welded. The main disadvantage of this method is the possibility of metal leakage from the weld and the appearance of carbon monoxide.
The third method is an intermittent melting, during which the workpieces are alternately dense or weakened in contact. The welding line is closed in the connection area with clamping tongs until their temperature rises to 950 degrees. This method is used if the power of the welding device is initially insufficient to perform continuous reflow.

Preparing parts and assembling spot welding

The standard design of the contact welding machine consists of a power section, a circuit breaker and a 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 home-made welding machine, it is only necessary to take the main parts from it. This is a transformer with a power supply, a control system and a switch.

In the manufacture of spot welding, first of all, the secondary winding must be removed 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 a remote secondary winding, another is superimposed, made of thick copper wire, with a cross section of about 2-3 cm. Then it is wrapped with insulating paper and varnished for additional insulation and fixation.

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

During the preparation of the transformer coil and the winding of the secondary winding, it is recommended to follow the mandatory rules. To calculate the number of turns, you can use the formula N \u003d 50 / S, in which N is the number of turns, and S is the core area (cm2). It will help speed up the calculations. Since parts from the inverter are used in the design, the parameters of the primary coil are first determined, the necessary calculations are made, and only then can the secondary winding be manufactured.

Pay attention to the grounding of both windings. This is due to the high power of the received current, which can be deadly when in contact with live parts. Along with careful insulation, tight laying of turns is of great importance. Otherwise, inter-turn short circuits may occur and the wires will burn out as a result of overheating. It is necessary to take care of the cooling of the transformer. It may be necessary to install an additional cooling system, which includes radiators blown by fans.

Additional elements of the welding machine

The next step after the manufacture of the transformer will be the manufacture of contact tongs. 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 gripper is manufactured according to the drive system and the dimensions of the parts to be connected.

The most important part of the pliers are 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, therefore, refractory metal should be used for their manufacture. Usually rods with a diameter of about 15 mm are used. The diameter of the cable to be connected is always smaller than the diameter of the lugs.

The wires are connected to the electrodes using conventional 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 parts that have failed without additional soldering work. All bolts and nuts must be copper. If it is supposed to impose connecting seams with a large length, in this case the tips are equipped with special rollers.

After the manufacture of the tongs, the time comes to solve an equally difficult task - providing the necessary pressure of the electrodes at the point of welding of the parts. The main difficulty is due to the fact that it is impossible to manually create a high and uniform pressure. If other options are not considered, then it is best to initially abandon the manufacture of spot welding from an inverter, because the efficiency of such an apparatus will be extremely low.

In industry, this problem is successfully solved by using amplifiers based on pneumatic or hydraulic systems. At home, making such devices is almost impossible. For homemade spot welding, a compressed air system, which is powered by a conventional pneumatic compressor, is best suited. The most optimal maximum indicator required for normal operation will be the force at the ends of the electrodes, which is 100 kg or more. The change in pressure occurs with the help of a separate regulator, which can also be built into the overall control system.

At the final stage of the assembly of contact welding from the inverter, it remains only to mount the entire system. For installation, it is recommended to use ready-made elements, which greatly simplifies assembly and improves performance. All the missing parts are in the inverter, from which the transformer has already been taken.

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

The spotter is a rather useful device that helps to significantly increase the efficiency and speed of work. in car body repair. But this unit has a fairly high cost with a simple design. Therefore, many craftsmen prefer to make a spotter from an old transformer or from a do-it-yourself welding machine.

When repairing a car body, it often becomes necessary to remove dents, for example, after an accident. Various methods are used for this: pulling out dents with suction cups, leveling with hammer blows from the back of the part, etc. In the latter case, the part must be dismantled to eliminate the defect.

The use of a spotter allows you to significantly speed up and simplify the process of aligning car parts. This unit is a kind of spot contact welding, with which you can weld washers, studs, bolts, hooks and other fasteners to damaged areas of the car body. In the future, various tools are hooked on them to level the dents.

The spotter can also be used for soldering, heating, hardening and upsetting surfaces to be leveled.

The device and principle of operation of the spotter

The spotter consists of the following elements:

welding machine, which can be transformer or inverter type;
cables (power cable and mass cable);
welding gun (stadder);
an electrode with an inertial hammer.

When you press a button on the studder, current begins to flow to it. Depending on the selected mode, the current supply can be constant or in the form of one short pulse. Further, the current is supplied to the electrode, which can have tips of various shapes.

The machine is working according to the following principle.

The place on the car body that needs to be leveled is cleaned of paint. You should also clean a small area for connecting the mass cable.
Any fastener, for example, a washer, is attached to the spotter electrode and welded to the straightening place.
An alignment tool clings to the washer, after which the dent is pulled out.

Pulling dents can be carried out and without welding fasteners. In this case, a pointed tip must be installed on the electrode with an inertial hammer. The electrode is applied to the desired location of the part, and the tip is welded to it with a short current discharge. Further, without removing the electrode from the part, they strike with a hammer in the opposite direction from the tip, thereby pulling out the dent (a reverse hammer cannot be used on aluminum). After the defect is eliminated, the welded end of the electrode breaks off easily.

How and from what to make a spotter

The transformer for the spotter is noticeably different from the classic welding transformer. In arc welding, the metal is heated by an electric arc, and in spot welding, heat is released due to the transition resistance in the electrode-metal section. This occurs during arc welding if, for example, the wrong operating mode is set on the machine. In this case, the electrode sticks to the metal, which can cause damage to the device.

To prevent this from happening, spot welding is carried out in pulse mode of current supply(up to 1 second). And since spot welding does not require arcing, the voltage in the spotter should be minimal (about 6 V), and the current strength should be high (at least 1000 A).

From the welding machine

It is impractical to make this unit from an inverter, if only because spot welding does not require direct current. In addition, you will have to redo the transformer in order to achieve high current rates. With such success, you can make a spot welding unit from scratch. If there is an inverter device, then it is better to use it for its intended purpose, and to adapt a conventional transformer welder for the spotter.

As for semi-automatic machines, all universal models of these units already have the function of pulsed welding, and they will not need to be modified. But if a broken, ordinary semiautomatic device is available, then it will need to redo the transformer.

Welding machine Aurora

Alteration of the transformer consists in removing the secondary winding and winding a new one. The spotter requires a welding current of 1000 A or more. If the calculations assume that the current density is 8 A per 1 mm 2, then its cross section should be about 120 mm 2. But winding a wire of such a cross section is quite difficult. Therefore, you can take a tire with a smaller section, for example, 80 mm 2, if the device is not used in too intensive mode.

Advice! You can achieve the required cross-sectional area by folding several thin tires together and wrapping them with fabric electrical tape.

For determining the number of turns do the following.

Wind any conductor covered with insulation on the magnetic circuit. 10 turns will be enough.
Connect the primary winding to the network, and measure the voltage on the improvised secondary.
The result obtained must be divided by the number of turns, that is, by 10. As a result, you will get a value that determines the number of turns to obtain 1 V of voltage. But since the spotter requires a voltage of 6 V, multiplying the resulting value, you can find out the number of turns.

Based on the diameter of the wire with the required cross section, it can be determined whether this winding will enter the free space between the primary and secondary windings of the transformer (not yet removed). If there is enough space, then the secondary can not be removed from the magnetic circuit, but a new winding can be wound over it. In this case, the welder can be used and for arc welding, and for a dot.

A modified transformer is not the only part required to make a spotter out of a welding machine. It needs to be added electronic discharge control unit and a small transformer to provide power to the module. Below is a diagram of the block that controls the spotter.

This scheme works as follows.

When the circuit is closed by switch S1, current is supplied to the primary transformer T1.
Next, the capacitor begins to charge. It is connected through a closed switch contact to a diode bridge.
The output transformer T2 will be de-energized until the switch button S is pressed. After that, the voltage from the capacitor through a variable resistor will go to the control electrode of the thyristor. Further, the voltage will go to the primary of the output transformer, after which a pulse will appear on its secondary winding with the current strength necessary for welding.
After the capacitor is discharged, the module returns to its original state. To repeat the pulse, press the switch again.

After the control unit is ready, all components are placed in a plastic or metal case.

From battery

This device, made from a 12 V battery, is mobile and can work regardless of the presence of the mains. For the manufacture of the unit will require the following components.

The assembly of the device is carried out according to the scheme below:

a mass cable is connected to the negative terminal of the battery, which must be in contact with the part prepared for repair;

the first contact of the relay is connected to the positive terminal of the battery;
a cable is connected to the second contact of the relay, which goes to the welding gun;
a start button is installed between the first and third (connected to the battery plus) contact of the relay;
solenoid relay must be connected to ground.

The cross section of the cables should be about 100 mm 2, and their length should not exceed 1.5 m. The only drawback of this device is that the battery runs out quickly, and it takes time to charge it.

From the microwave

To make the device, you need a transformer removed from the microwave. But for reliability it would be better if use two coils. From each transformer, the secondary winding should be removed and instead of it, a pair of turns should be wound with a cable with a cross section of at least 50 mm 2.

The primary windings of both transformers are connected in parallel. Further, the spotter control module, which was discussed above, is connected to the circuit. You can also simplify the design of the spotter if you include a time relay and a retractor relay from the car in the circuit. You can find out how this is done in this video.

Important! Despite the low voltage - 6 V and less, the current received at the output of the transformer has huge values, about 1000 A, which poses a great danger to human life. Therefore, both windings of the transformer must be grounded.

welding gun

For the manufacture of the welding handle, no drawings are required. Best for this purpose glue gun body. You will also need a copper rod with a diameter of about 20 mm.

On one side of the rod, it is necessary to cut the thread (M14x1.5). Various nozzles for welding will be wound on it. On the other side, a hole is drilled and an M8 internal thread is cut. The cable will be attached to this place. Also on the details should make a few stitches so that it is better fixed inside the case.

It remains only to find a suitable button, place it in the case and connect it to the electrical circuit of the device.

Spot welding can be found not only in production, but also in domestic conditions. The advantage of choosing this type of welding lies in its reliability. This way of fastening is easy to connect different-carbon steels, non-ferrous metal. At the same time, it is possible to build almost any configuration and combination with metals.

Allows you to create a product for any fantasies and needs.

Application spectrum

Most often, spot welding has been widely used in the repair of cables and household appliances. allows you to repair batteries and other mobile portable devices.

Welding technology

The battery welding technology is quite simple, an example can be seen in the video below.

The whole welding process consists in heating the working metal surface to a plastic state. In this state, the products are easily deformed and connected.

Continuous melting is required to ensure quality. Continuity and a certain speed of the working pace, pressing force are key in the work. In the future, these parameters characterize the quality of products.

The basis of the principle of operation of this welding is the conversion of electrical energy into thermal energy. Under the influence of heat, the metal surface undergoes melting.

The electrode contact should be placed at the junction of 2 working surfaces of the parts required for fixing.

The solidification of the molten mass occurs at the moment the current is turned off. This eliminates the effect of spreading the surface of the seams. Therefore, this type of welding is called spot welding.

Ticks

Attachment of parts of parts is carried out by fixing the surface with the help of special pliers. Which are divided into suspended and manual.

Suspended. Have received wide application in the conditions of the plant and industrial enterprises, are subject to repeated use.
Manual. The main function is the transmission of electric current to the electrodes.

Several advantages

High speed of work;
The highest degree of electrical safety;
Ensuring a quality connection;
You can make a device for welding manually.

Technical process

The whole system is built on elemental heat transfer in order to melt the metal at the fixing points. Welding quality can be affected by poor surface cleaning, visible oxides.

Using the law of thermal conductivity, this parameter should be taken into account for most common metals. The thermal conductivity parameters for some of them are presented in the table below.

Metal name	Melting point, Сᵒ
Iron (low carbon steel)

Aluminum

The electrodes must also meet certain parameters:

Thermal conductivity;
electrical conductivity;
Mechanical strength;
Processing speed.

The electrodes are short-lived and require careful handling. With constant exposure to temperature conditions, it is necessary to interrupt. This feature allows the electrodes and the welded surface to cool down. Thus, the service life of the electrodes is extended.

The diameter of the electrodes affects the characteristic of the current strength, and, accordingly, the quality of the seam. The diameter of the electrode section is selected based on the thickness of the working surface. The electrode should be approximately twice as thick as the workpieces to be fixed.

contact welding

Contact welding and allows you to work in normal home conditions. But, most often, this method is widely used in industry.

Manufacturers made sure that bulky spot welding machines were not present at home. Compact mobile devices have long been invented. Their purpose is to repair household appliances.

Such a device is called a spotter. The device is equipped with two terminals designed to secure one of them to the working surface of the product. The second output is connected to the electrode.

In this configuration, it is not necessary. The power source should be located at a sufficiently close distance from the place of work.

You should not pay attention to a small-sized device, it is quite functional for its size.

The simplest devices use single-phase current. But you should not hope to fix the part by more than one millimeter. Fastening of more complex parts is carried out with the involvement of an additional transformer.

Price

The cost of spotters is quite low. In the most expensive category are inverter.

As a rule, household devices do not require large capacities. Therefore, you can get by with a homemade device.

Spot welding is distinguished by its quality of the seam. In most cases, in order to destroy it, the use of serious mechanical influences is required. Most often, drills are used for this.

Apparatus scheme

If there is such a need, there is a desire to make the device yourself, then it is quite possible to assemble it at home.

The size of the spot welding machine depends primarily on the needs. The most convenient are devices with medium dimensions.

Drawing. The scheme of the welding machine for spot welding.

The operation of the device is based on the Lenz-Joule principle. The requirement of physical law states that the conductor must generate heat in an amount equal to the proportion of the resistance of the conductor, as well as the square of the current and the elapsed time.

Such a circuit solution requires the installation of a rectifier bridge. The capacitor is charged through the thyristor bridge. The first thyristor acts as a cathode.

The capacitor bank is a kind of protection and serves as a current releaser. A swing principle is created, constant charging and discharging of capacitors. This principle allows you to create the effect of spot soldering. The seam cools evenly and in a timely manner, preventing the metal from spreading.

To increase the power in the circuit, an additional thyristor with a shutdown relay is also added.

Homemade apparatus

An important part of the welding machine is the transformer. The minimum power value should be 750 watts.

Video on creating your own device.

You can create a device using an inverter. Before proceeding to the goal, it is necessary to have some skills in the field of electrical engineering.

A circuit using a transformer instead of an inverter is considered simpler. But such devices are not powerful enough to work with metals of sufficient thickness of more than 1 mm.

Device Creation Steps

Remove the transformer from an unnecessary microwave;
Get rid of the secondary winding, fasteners, shunts;
Make the secondary winding with a thicker wire than in the primary;
Check the assembled device for current leakage;
Leaks should be repaired with insulation using tape;
Check current strength. The value should be no more than 2 kA.

Copper wire of considerable thickness is most suitable as tips or electrodes. The tips are sharpened and fixed.

On the market, the inverter is presented in a large assortment, where anyone can choose the necessary equipment for welding at home. An alternative is to make it yourself.

You should familiarize yourself with the design and features of the inverter, the nuances of contact welding, detailed instructions for independent welding. We will also learn about making a homemade welding device from car batteries and a microwave.

Technological aspects of resistance welding

It's not just car enthusiasts and homeowners who require welding work. A welding inverter may be required in a small workshop or at home for the installation of metal parts.

The principle of operation of the inverter is based on heating the metal from an electric current, after which it melts and solidifies with the formation of a weld. To fix the parts to be welded, protecting them from being pulled apart, the parts should be compressed with electrodes through which current is transmitted.

To perform home welding, you will need power from powerful sources, which can cause household wires to overheat. Therefore, you should first check the quality of the wiring and, if necessary, replace it.

During the connection of two blanks along the adjacent edges. This method is used when mounting small parts, thin material, metal rods up to 0.5 cm thick.

Part welding options

Surfaces can be connected in three ways: continuous or intermittent fusion, resistance. During fusion welding, workpieces or metal sheets are connected and heated with current until they are melted. This technology can be used in the processing of non-ferrous metals, low-carbon steels, the installation of steel, brass and copper. But this method is rarely used because of the stringent requirements for temperatures, the absence of impurities in the connecting zones.

During continuous melting of workpieces, other types of clamps are also used. The parts are connected when the current is turned on. After the edges of the mounted parts are melted, upsetting is carried out and the current supply is turned off. This method is used in the installation of thin-walled pipelines, but it is possible to connect workpieces that differ in structure. The main advantage of the method is the speed of execution. However, metal can flow out of the weld with the appearance of waste.

With sequential tight or weak contact, intermittent melting is carried out. With the help of clamping tongs, the welding line is closed in the area where the workpieces are joined until their temperature reaches 900-950°C. This method is used when the initial power of the device for continuous reflow is insufficient.

As a result of resistance welding, the user performs the following work:

All of the listed types of welding processes have a similar technology of work, but differ in the fastening of parts and current supply.

For household welding of parts in a dotted way, you can make a device with your own hands. In it, the main working mechanisms will be a clamp, a device for supplying voltage to capacitors, in which an electrode is attached to a low-voltage winding. The other clamping wing is a support wing, it can be mounted with a workpiece of large parameters.

Production of a welding device from a microwave oven

As already mentioned, a contact welding machine can be made by hand, where the main part is a transformer from a microwave oven. Performing such a device, it is necessary to make preliminary calculations of the profitability of such a device in comparison with the purchase of a finished inverter.

The most expensive part in a home-made device is a transformer, the rest of the consumables (the base for attaching parts, a casing with wires) can be taken from a repair service.

A transformer should be prepared, the power of which will start from 1 kW, so that the welding equipment made from it can connect sheets up to 1 mm thick. If the power of the transformer is doubled, it will be possible to process sheets up to 1.8 mm thick. In modern microwave ovens, the power of the transformer can be 3 kW.

To increase the current power, it is possible to use 2, 3 transformers.

The transformer must be pulled out of the protective casing, the shunts and the secondary winding must be removed. Due to the high voltage used in the microwave, there are fewer loops on the primary winding of the device compared to the secondary winding. To remove the potential difference, we will have to upgrade the secondary winding, and adapt it for the purpose of spot welding.

The transformer is cleaned in detail from the remnants of the shunts and the secondary winding; if necessary, you can use a long narrow object or a metal brush. That is, the secondary winding must be made new, but the primary remains in the same form. To do this, you need to take stranded wires, the cross section of which should not be less than 1 square (due to the high voltage of the future transformer). For the secondary winding, you can make 2-4 turns of wiring (you get a voltage of 2W), but because of the thick insulating layer, it cannot be bent around the coil. Therefore, the wire must be cleaned of insulation and wrapped with electrical tape.

When using a circuit of several transformers, the secondary windings should be combined. If one transformer is used, then the microwave oven housing can be used for it, reduced in length and width.

The casing for several transformers can be made of iron sheet, covering it with an insulating material (duct tape).

To bring current to the welding area, a lever device is created. Where one lever is firmly attached to the main surface (to be comfortable, a transformer with a casing is also attached with clamps). During lowering, the second lever will press on the parts.

The switch is inserted into the primary winding circuit, mounted on the upper arm, which will help to simultaneously start the current and compress the part. In this case, pliers will not be used, but tips with wiring are pre-soldered to prevent oxidation.

Resistance welding will use thicker copper rods (compared to the dimensions of the wiring). During operation, they will be sharpened or replaced.

During operation, the part will be clamped by levers between a pair of electrodes and a current will be started.

Production of a welding device from batteries

During welding work with an electric welding device, a high load is placed on household networks. Long-term spot welding can melt wires or break household equipment. Therefore, the welding device can be powered by an independent power supply. For such purposes, a portable generator is suitable, which is powered by diesel fuel or gasoline, which you can buy or do it yourself.

You will need several batteries from machines that were in operation (preferably one energy intensity). In this case, the calculation of the current strength will be 1/10 of the battery capacity. If batteries of different capacities were used, then the calculation can be performed using the smallest capacity.

A circuit is created from batteries that have been connected in series. Their "minuses", "pluses" are fastened with wire cutters, wires or wiring for the cigarette lighter. Any pliers can also be used. The wire is removed from the free "minus" to the electrode, it is clamped with tongs. From the free "plus" to the working plate, a rheostat is installed in the circuit.

Charging equipment can be made to ready-made resistance welding equipment.

As a result of the analysis of all options for self-assembly of equipment for spot welding, the availability of this method becomes clear. Thanks to the above information, users can get the initial skills of spot welding, independently make an inverter for resistance welding from existing materials.

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

Below you will learn what resistance welding is, how to make a device based on a microwave or a battery, and how to use it correctly.

Welding work at home may need to be done by everyone during repairs. An inverter can be useful for installing metal parts or in a mini-workshop at home.

The principle of operation of the inverter is as follows:

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

Do-it-yourself welding requires a powerful power source, and this can lead to to overheating of household wires. Check the quality of your wiring in advance, 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

In resistance welding, surfaces can be connected in the following ways:

continuous reflow;
intermittent;
resistance.

During operation, with the help of reflow, parts or sheets of metal must be connected or heated with current until melting. This technology is relevant for such 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 strict temperature requirements are imposed, and also because there should not be any in the connecting zones impurities.

With continuous melting of workpieces you will need welding tongs and other clamps. 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. Thus, thin-walled pipelines are mounted, however, 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 flow out of the weld with the appearance of waste.

Intermittent reflow is performed with consistent tight or loose contact. By means of clamping tongs, the welding line is closed in the area of \u200b\u200bjoining the workpieces so that the temperature rises to 900-950 degrees. This method is used in case of insufficient initial power of the device for continuous reflow.

Contact welding solves the following tasks:

the surface for installation is prepared (the contours are cleaned and leveled);
the edges of the workpieces are connected and fastened with clamping parts;
includes a current source;
the edges of the blanks when the device is running warm up and melt;
precipitation is performed and the current is switched on.

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

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

clip;
capacitor voltage supply. In it, an electrode is attached to the low-voltage winding.

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

DIY microwave equipment

The apparatus for carrying out welding work by the contact method can be made by hand, the key part in it is It's a microwave transformer..

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

For a home-made device, the most expensive part is a transformer, but consumables (such as a base for fasteners or a casing with wires) can be taken from a 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 much, then it is suitable for processing sheets up to 1.8 mm thick. Many microwave ovens are equipped with a 3 kW transformer.

To increase the current power, 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 the voltage in the microwave oven is high, there are fewer loops on the primary winding of the appliance 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 conclusions of the secondary windings are combined when using a circuit based on several transformers. And subject to the use of one transformer, the microwave housing can be reduced in width and length.

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

For supplying current to the area to be welded you need to create a lever device. One lever is firmly attached to the main surface, and during lowering the second will press on the workpieces.

Insert the switch into the primary circuit and install it on the upper lever, thanks to which it will be possible to start the current and compress the part at the same time. Tongs in this case will not be needed, it will be necessary to solder the tips with 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 welder

During welding with electrical equipment a huge load is placed on household networks. As a result of long spot welding, the wires can melt or household equipment will break. Accordingly, the device can be powered from an independent source. For example, a portable generator that runs on gasoline or diesel fuel. Such a generator can be purchased or made by yourself.

You will need several batteries from used cars. In this case, the calculation of the current strength will be 1/10 of the battery capacity. When using batteries of different capacities, the calculation can be made using the smallest capacity.

You will need to create a circuit of series-connected batteries. "Pros" and "cons" are fastened with wire cutters, wires or wires for the cigarette lighter, or any pliers. The wire is led out from the free "minus" to the electrode and clamped with tongs. From the free "plus" towards the working plate, a rheostat is placed in the chain.

When the equipment is ready, you can make additional equipment for charging.

Features of a homemade welding machine

Contact welding in technological terms not too complicated, but in order to achieve the desired quality of the connection, you need to properly manage it. Therefore, a home-made microwave-based device will need to be equipped with special controls. The key ones are the lever, the switch, and also the lever, through which the compression force of the electrodes and the parts that are connected is exerted.

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

The force transmitted by the electrodes can be increased not only by a lever, but also by a lever-screw mechanism, which can also be attached to a home-made device. It is best to attach it directly to the lever so that the manipulations are quick. Also, this placement will free up the second hand so that you can support the details.

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

A switch to control welding will need to be placed in the primary winding circuit. And if it is installed in the secondary winding circuit, through which a significant current passes, then additional resistance will be created, as a result, the electrodes will weld to each other.

Also, a home-made microwave-based apparatus will need to be equipped with a simple cooling system, which you can also do yourself. For such a system, you can take a conventional fan, with which you can cool the electrodes, transformer, and other conductive elements. Naturally, this cooling is not very efficient, and you will need to take regular breaks so that all the heating elements of the equipment can cool themselves.

The above have been discussed do-it-yourself spot welding equipment assembly features. This method is available to everyone, since the materials for work are not too expensive, and spot welding skills can be mastered very quickly.