Before making a welding machine, you need to have an idea of ​​what a step-down transformer is. People with minimal knowledge of electrical engineering can do it themselves. The production of such products was especially important in those days when this kind of equipment was not mass produced and was not available to a wide range of buyers. And the need for use and welding metal structures for household needs has always been and remains now. Welding is the simplest and in a fast way for connection metal parts.

Types of welding and types of welding machines

There are several types of welding, including plasma, electroslag, arc, laser, beam, ultrasonic, gas and contact, as well as many others. IN household, as a rule, it is enough arc welding electric type. For electric arc welding there are transformer and inverter devices. To get a device for direct current, you need to slightly change and remake the device configured for alternating current. But the advantage nevertheless remains with modern inverter models, whose mass is much less. Such devices have current stabilization and operate at reduced mains voltage, but are sensitive to overheating, which requires caution.

The design of the transformer apparatus is simple and reliable. You can make your own AC welding machine using transformers. The electric arc of this device is produced by high voltage current, and the device itself must have high power. The transformer used to make the welding machine must withstand prolonged and significant loads without overheating. The most convenient model for manufacturing is the one whose core is shaped like the letter “P”, since it can be easily disassembled and it is easier to wind a winding on it (Fig. 1). But if it is not possible to find this type of core, it is permissible to use a toroidal type core with round, which can be found in an electric motor, lator or stator. The calculation formula for it will be similar, but has several differences.

The transformer consists of coils of enameled copper wire wound around a core. The number of coils rarely exceeds 2, and there are also 2 windings on them - primary and secondary. Windings contain different quantities turns. The primary is connected to the electrical network and induction occurs, imparting a current of lower voltage, but more amperes, to the second layer of the winding. A low current will negatively affect the quality; too much current will cut the metal being welded and burn the electrodes.

How to make a transformer welding machine yourself: materials and tools

Figure 1. Winding on a “U” shaped core.

• transformer iron;
• copper wire;
• winding;
• core;
• thermal paper;
• technical cardboard;
• fiberglass;
• electrical varnish;
• fan.

Iron for a welding machine must have a high degree of magnetic permeability. Ideal thickness The winding is 0.3 mm; copper sheet 40 mm wide is used for it. Thermal paper is needed to wrap the entire winding in it; its thickness must be at least 0.05 mm.

If you use an ordinary wire for the winding, it may happen that the surface of the conductor becomes very hot. The fan is installed inside the transformer of the welding machine for the same purposes.

In order for a household welding machine of this type to cope with electrodes with a diameter of 3-4 mm, its core must have a cross-section from 22 to 55 cm². A larger value will not provide more power, but the device will be significantly heavier. The transverse area of ​​the core is calculated using the formula S=a*b. For the primary winding, a wire insulated with fiberglass or cotton, resistant to temperature influences, would be very good. It is this insulation that will ensure the device long-term operation without overheating; in extreme cases, rubber insulation can be used.

The insulating layer, if fiberglass or cotton fabric is available, can be made independently. To do this, you need to cut the fabric into narrow strips of 2 cm and wrap them around the wire, and then impregnate the winding with electrical varnish.

Correct winding of coils

In order to wind the coils correctly, you first need to make a frame, which must fit loosely onto the core from above. The material for manufacturing can be textolite or, in its absence, technical cardboard. After winding the first row, it is necessary to lay a layer of insulation. The materials can be fiberglass, technical cardboard, textolite. Then another layer of copper winding is wound, and the second coil is made in the same way.

Particular attention must be paid to the primary winding, since it is the most difficult to rewind, and yet during the welding process the temperature often reaches 100°C or more. It is most convenient to work together at this stage, so that while one is laying the turns, the other is pulling the wire.

Safety precautions and device testing

Before work, you need to check the device, the voltage for which should be from 60 to 65 V. For higher powers, additional layers of winding will be required; they are usually made on industrial models. The voltage Ucb during the process should not be higher than 18-24 V, this depends on the diameter of the electrode. It will also be necessary to increase the winding if the magnetic permeability of the transformer iron was initially calculated incorrectly. Compliance with the rules is also required fire safety during work, since sparks from welding can burn for a long time and, falling on some objects, thus setting them on fire.

The welding machine is designed to perform a relatively small amount of work. And therefore, after using 10-15 electrodes of 3 mm in diameter, it should cool down. If 4 mm electrodes are used, the work time needs to be reduced even further. The device heats up the most when using the cutting mode. After completing the work, the device must be disconnected from the network.

DIY inverter welding machine

The circuit diagram of such a device contains accessible components; assembling it yourself is not difficult. This type of work requires knowledge of electronics and considerable experience. Many used radio components can be found in old televisions. Materials and tools:

• electrode;
• SCRs;
• diodes;
• pay;
• fan;
• diode bridge.

For proper operation the inverter requires a current with the possibility of smooth regulation from 40 to 130 A. For the primary winding of the transformer, the primary current must be 20 A, and an electrode of no more than 3 mm will provide quality work. The welding voltage must be switched on and off using a conveniently located button. Thin sheets of parts will allow reverse polarity to be cooked.

It is most convenient to arrange all the elements of the diagram on printed circuit board. The SCRs and diodes used in the circuit should not overheat; for this, before installing them, a heat sink is mounted on the board, and on it, in turn, they themselves are mounted. The board must be made of fiberglass with a thickness of at least 1.5 mm. A fan is required for better cooling of the entire circuit; it is mounted directly on the housing to accommodate the inverter.

Working with an inverter is easier than performing similar operations with a transformer apparatus.

This results in a much better quality seam. This machine has the ability to weld ferrous and non-ferrous metals and workpieces from thin sheets.

No work with iron can be done without a welding machine. It allows you to cut and connect metal parts of any size and thickness. A good solution is to do the welding yourself, because good models are expensive, but cheap ones are low quality. To implement the idea self-made you need to get a welder special equipment, allowing you to hone the quality skills of a specialist in real conditions.

Types and characteristics of the tool

After everything necessary conditions preparatory stage successfully met, the opportunity opens up to make a model of the welding device with your own hands. Today there are many schematic diagrams that can be used to make a device. They follow one of the following approaches:

• Direct or alternating current.
• Pulse or inverter.
• Automatic or semi-automatic.

It is worth paying attention to the device, which belongs to the transformer type. An important characteristic of this device is its operation on alternating current, allowing it to be used in domestic conditions. AC machines are capable of ensuring the standard quality of seams welded joints. A unit of this type can easily find its use in everyday life. when servicing real estate located in the private sector.

In order to assemble such a device, you must have:

• About 20 meters of cable or large-section wire.
• A metal base of high magnetic permeability that will be used as the core of the transformer.

The optimal core configuration has a U-shaped core base. In theory, a core of any other configuration could easily be suitable, for example, a round shape taken from a stator that has become unusable for an electric motor. But in practice, winding a winding on such a base is much more difficult.

The cross-sectional area for a core belonging to a home-made household welding machine is 50 cm 2. This will be enough to use rods from 3 to 4 mm in diameter in the installation. Usage larger section will only lead to an increase in the mass of the structure, and the efficiency of the device will not become higher.

Manufacturing instructions

For the primary winding, it is necessary to use copper wire with high heat resistance, since when performing welding work it will be exposed to high temperatures. The wire used must be selected according to fiberglass or cotton insulation, intended for stationary use in high temperature zones.

For the winding of the transformer, it is not allowed to use wire with PVC insulation, which will immediately become unusable when heated. In some cases, the insulation for the transformer winding is made independently.

To perform this procedure, you need to take a piece of cotton fabric or fiberglass, cut it into strips about 2 cm wide, wrap them around the prepared wire and impregnate the bandage with any varnish that has electrical properties. Such insulation in terms of thermal characteristics is not inferior to any factory analogue.

The coils are wound according to a certain principle. First, half of the primary winding is wound, followed by half of the secondary. Then proceed to the second coil using the same technique. To improve the quality of the insulating coating, fragments of strips of cardboard, fiberglass or pressed paper are inserted between the layers of windings.

Equipment setup

Next you need to configure. It is performed by connecting the equipment to the network and taking voltage readings from the secondary winding. The voltage on it should be from 60 to 65 volts.

Precise adjustment of the parameters is carried out by reducing or increasing the length of the winding. To obtain a high-quality result, the voltage on the secondary winding should be adjusted to the specified parameters.

To the primary winding of the finished welding transformer connect the VRP cable or the ShRPS wire, which will be used to connect to the network. One of the terminals of the secondary winding is fed to the terminal to which ground will subsequently be connected, and the second is fed to the terminal connected to the cable. The last procedure is completed and the new welding machine is ready for use.

Production of small-sized units

An autotransformer from a Soviet-style TV is easily suitable for making a small welding machine. It can easily be used to produce a voltaic arc. In order for everything to work out correctly, graphite electrodes are connected between the terminals of the autotransformer. This simple design allows you to perform several simple work using welding, such as:

• Making or repairing thermocouples.
• Heating high-carbon steel products to maximum temperature.
• Hardening of tool steel.

A homemade welding machine, created on the basis of an autotransformer, has significant drawback. It must be used in accordance with additional measures precautions. Without galvanic isolation from electrical network, it is a rather dangerous device.

The optimal parameters of an autotransformer suitable for creating a welding machine are considered to be an output voltage ranging from 40 to 50 volts and low power from 200 to 300 watts. This device is capable of delivering from 10 to 12 amperes of operating current, which will be sufficient for welding wires, thermocouples and other elements.

As electrodes for a DIY mini welding machine, you can use leads from a simple pencil. The terminals found on various electrical appliances can serve as holders for improvised electrodes.

To carry out welding work, the holder is connected to one of the terminals of the secondary winding, and the part to be welded to the other. The handle for the holder is best made from a fiberglass washer or other heat-resistant material. It should be noted that the arc of such a device acts for a fairly short time, preventing the used autotransformer from overheating.

A welding machine is used in some types of body work to connect metal parts. However, work using these devices is usually carried out in the presence of serious damage to the body, which is relatively rare. Therefore, purchasing a new, relatively expensive device for one-time use is not advisable. For household use You can make a welding machine with your own hands.

Peculiarities

It should be borne in mind that making a welding machine yourself is profitable only if you have some initial components. This is because, although it is not difficult to assemble a simple model of the device in question, the materials required for this are very expensive. Therefore, if you purchase them separately specifically for making this device yourself, in terms of the final cost it may be close to a new branded tool, which, of course, will surpass the technical characteristics of a homemade welding machine.

The basis of the instrument in question is a transformer, which serves as a source of energy. It consists of two coils of copper wire wound around a metal core. Moreover, the coils differ in the number of turns. The one that is connected to the electrical network is called primary. In this case, a current of lower voltage but higher amperage arises in the secondary coil due to induction.

It must be taken into account that a welding machine with a low current produces low-quality welding, while an excessively high current leads to burning of the electrodes and cutting of the metal.

The welding machine can be equipped with a transformer, for example, from a microwave oven. However, since a voltage of about 2000 volts appears on its secondary winding, it is necessary to make some changes to the design with your own hands in order to lower the voltage, namely, reduce the number of turns.

To reduce the voltage, the secondary winding is sawed in two places and pulled out of the coil. In this case, care must be taken not to damage the primary winding. Then the secondary winding is rewound with a thicker wire or PEV wire with enamel insulation or thermal paper 0.05 mm thick. It is advisable to use the third option, as this avoids the skin effect that occurs when using conventional wire. It consists of displacing high-frequency currents, which leads to overheating of the conductor.

The created winding is coated with thin-insulating varnish. Parameters such as the number of turns and thickness are calculated for each transformer model. However, they also optimal values: winding thickness - 0.3 mm, width - 40 mm, wire thickness - 0.5-0.7 mm.

If you don’t have a transformer from a microwave oven or any other device, you can assemble it yourself. This will require a core with cross section 25-55 cm² of transformer iron, characterized by high magnetic permeability, copper wire several tens of meters long, insulating materials.

As for the wire, the best option is considered to be heat-resistant copper wire with fiberglass, cotton or, in extreme cases, rubber insulation. You can do the insulation yourself. To do this, you need to cut the insulating material into 2 cm strips and wrap them around the wire.

The final stage is impregnation with electrical varnish. The better the insulation, the lower the possibility of the instrument overheating. Winding parameters are calculated based on technical characteristics device. Output voltage idle speed homemade welding machine ranges from 60 to 65 V, operating voltage - from 18 to 24 V. With the highest power and an electrode with a diameter of 4 mm, the power in the secondary winding is 3.5-4 kW, in the primary - about 5 kW, taking into account losses . The current is about 25 A.

The number of turns is determined based on the voltage, taking into account the cross-sectional area of ​​the magnetic core of 2 cm. For 1 V with a high-quality wire there are 0.9 - 1.1 turns. The total is obtained by dividing the voltage level by the frequency. In this way, indicators are calculated for both windings. Based on this, you can determine the required wire length by multiplying the length of one turn by their total number. In this case, you need to take some reserve.

Before winding the coils, you need to make frames from textolite or electrical cardboard, which are loosely placed on the core. Between the primary and secondary windings it is necessary to lay insulation in the form of fiberglass, electrical or ordinary cardboard.

Frame

The welding machine should be equipped with a housing in which the transformer is placed to protect it from external factors. When choosing or manufacturing it, you need to take into account that due to electromagnetic radiation, not all materials are suitable for this. The best options are a solid curved rigid steel case or a case made of dielectric materials. The second option is more difficult to find or assemble with your own hands, and it is also less durable, but it avoids vibration and energy loss in the structural elements of transformers caused by eddy currents, which are excited by strong magnetic stray fields near the windings.

In cases made of other materials, these negative phenomena can be somewhat reduced (by 30-50% depending on the design and material of the case) if longitudinal cuts are made on the case.

Most homemade welding tools do not have a solid body. This avoids problems associated with it such as vibrations, eddy currents and energy losses. However, in this case, the welding machine is exposed to external factors, which leads to a sharp decrease in the reliability and safety of work. In addition, it must be taken into account that the above-mentioned losses amount to several percent, which is almost imperceptible against the background of resistance in power lines and voltage fluctuations in the network.

In addition, it is advisable to equip the device with secondary voltage regulation for smooth regulation of the welding current. This will compensate for losses in the wires long length, which is especially important when working away from the power supply. Branded tools have step-by-step voltage regulation by switching windings. A home electric welding machine can be equipped with a voltage rectification circuit based on thyristors.

A home-made welding machine, in most cases, is not as reliable as a branded analogue. Therefore, during manufacturing, some measures should be taken to increase it.

The main factor leading to premature failure of the devices in question is considered to be overheating. To reduce the possibility of its occurrence, first of all, it is necessary to do effective insulation. This requires reliable winding wires with current density up to 5-7 A/sq.mm. However, this may not be enough.

To quickly cool the wire, it is necessary to ensure interaction with air. To do this, you need to make slots in the windings. After the first layer of wire and every two subsequent layers, getenax or wooden strips of 5-10 mm are inserted from the outer sides.

This ensures that each layer of wire is in contact with air on one side. If the welding machine does not have fans, the slots are oriented vertically to ensure constant air circulation. In this case, cold air comes from below, warm air goes up.

More effective option Naturally, the cooling of the welding machine transformer is provided by a fan. Blowing it has almost no effect on the heating rate, but significantly speeds up cooling. However, it must be taken into account that for a transformer with closed windings, the problem of overheating will not be solved even when installing powerful fan. In this case, it can only be avoided by moderate operation.

There is another option to solve the problem of transformer overheating. It consists of immersing it in transformer oil. This liquid not only removes heat, but also acts as an additional insulator. In this case, the transformer housing must be a sealed container.

The most problematic in terms of overheating are toroidal transformers. They heat up quickly and cool down slowly. Vibration that occurs during operation due to the attraction of metal elements by the variables they create is also considered a fairly serious problem with homemade transformers. magnetic field. Because of this, friction of the wires occurs, which leads to destruction of the insulation, as well as destruction and pushing through of the windings at the corners of the frame. To reduce the effects of vibration, it is necessary to make high-quality insulation. You also need to firmly secure all fixed elements.

Avoid storing and using the welding machine in conditions of high humidity. Water condensing in the cracks of the insulation acts as a conductor of current. The tool must be checked before use. If the voltage goes beyond 60 - 65 V, increase or decrease the winding.

Housework always requires a certain set of tools, devices, and a variety of equipment. This is felt especially acutely by owners of private homes and those engaged in various types of repairs in their own workshops and garages. Purchasing expensive equipment is not always justified, since its use will not be constant, but assembling a welding machine with your own hands is within the capabilities of every craftsman.

Before starting the process, it is necessary to determine the power of the device, because its dimensions and capabilities will depend on this. To familiarize yourself with the assembly procedure, you can watch the corresponding video, which shows how you can make a practical welding machine with your own hands. Its manufacture will require some theoretical training, as well as experience in electromechanical work. The assembly of an electrical device at home is carried out according to preliminary calculations, taking into account both the input and output parameters of the device.

This electrical apparatus It will be useful not only to welders who perform some work at home or in the garage, but also to ordinary craftsmen who use a welding device to build various devices.

Features of homemade transformers

Self-assembled devices differ from factory-made equipment technical performance. Do-it-yourself welding is made from available elements and assemblies, for which a welding transformer circuit is used. If the parameters of the component parts are strictly observed, the electric device will serve reliably for many years. Before doing welding transformer device with your own hands, you need to decide on the available components. The basis is a transformer consisting of a magnetic core, as well as primary and secondary windings. You can purchase it separately, adapt an existing one, or make it yourself. To make a welded electrical apparatus with your own hands, transformer iron and wire for windings will be added to the variety of tools from scrap materials. The manufactured transformer must be able to connect to a 220 V household power supply and have an output voltage of about 60-65 V for welding thick metals.

Features of homemade rectifiers

Self-made rectifiers allow you to weld thin sheet metal with high quality seam connections.

Diagram of a welding machine using rectification electric current quite simple. It contains a transformer to which a rectifier unit is connected, as well as a choke. This simplest design ensures stable combustion of the welded electric arc. A coil of coils wound on a core is used as a choke. copper wires. The rectifying device is connected directly to the terminals of the step-down transformer winding.

Depending on your goals, you can build a mini welded electrical apparatus yourself. It will cope perfectly with metals of small thickness that do not require the use of high currents when connecting. A spotter can be made from a welded electrical apparatus, which will significantly expand the possibilities of its use.

How to make a welding machine

A hand-made electric welding device is intended for performing minor work around the house, household or in the garage. At the first stage, the necessary calculations are performed and prepared assembly parts and nodes. To assemble a welding transformer with your own hands, it is advisable to decide in advance where to assemble the device. This will streamline the manufacturing process. Next to it are assembled assembly units that allow you to assemble a simple electric welding machine with your own hands. In addition to the main voltage converter, you will need a choke, which can be used from the elements of a fluorescent lamp. In the absence of a ready-made element, it is made independently from a magnetic core from a powerful starter and a wire made of copper conductors with a cross-section of about 1 mm square. A self-made electric welding machine will differ from its counterparts not only in appearance, but also in characteristics. To decide how to make it, check out the similar devices in the photo or video.

Calculation of a welding transformer

Homemade electric welding devices are made according to the simplest scheme, which does not provide for the use of additional nodes. The power of the assembled electrical apparatus will depend on the required value of the welded electric current. Welding at the dacha electrical device assembled with your own hands will directly depend on the technical characteristics of your own product.

When calculating the power for welding, take the strength of the required welding current and multiply this value by 25. The resulting value, when multiplied by 0.015, will show the required cross-sectional diameter of the magnetic core for welding. Before making calculations for the windings, you will have to remember other mathematical operations. To obtain the cross-section of the higher voltage winding, the power value is divided by two thousand, and then multiplied by 1.13. The calculation method for the primary and secondary windings is different.

To obtain winding values low voltage transformer will have to spend a little more time. The cross-sectional area of ​​the secondary winding depends on the density of the welded electric current. For values ​​of 200 A this will be 6 A/mm sq., with figures of 110-150 A - up to 8, and up to 100 A - 10. When determining the cross-section of the lower winding, the strength of the welded electric current is divided by the density, and then multiplied by 1.13.

The number of turns is calculated by dividing the cross-sectional area of ​​the transformer magnetic circuit by 50. In addition, the final welding result will be influenced by the output voltage. It affects the characteristics of the process and can be increasing in current, flat or steep. This affects the oscillations of the electric arc during operation, in which important are minimal current changes when working at home.

Welding transformer circuit

The figure below shows a diagram of a welding transformer of the simplest type.

You can find electrical circuits that will be supplemented with straightening devices and other elements to improve the welded electrical apparatus. However, the main component is still a conventional transformer. The wiring diagram for connecting its wires is quite simple. The welded device is connected through an electrical switching device and fuses to a 220 V household power supply. The use of electrical protective devices is mandatory, as this will protect the network from overloads during emergency conditions.

a – network winding on both sides of the core;
b – the corresponding secondary (welding) winding, connected in counter-parallel;
c – network winding on one side of the core;
d – the corresponding secondary winding, connected in series.

Defining parameters

To make an electric welding machine, you need to understand the principle of operation. It converts the input voltage (220 V) into a reduced voltage (up to 60-80 V). During this process, the low electric current in the primary winding (about 1.5 A) increases in the secondary (up to 200 A). This direct dependence of the operation of transformers is called the voltage-current characteristic of the step-down type. The operation of the device depends on these indicators. Based on it, calculations are carried out and the design of the future apparatus is determined.

Nominal operating mode

Before welding, it is necessary to determine its future nominal use. It shows how long home-made welding equipment can be continuously cooked and how long it should cool down. This indicator is also called the duration of inclusion. For homemade electrical devices, it is located around 30%. This means that out of 10 minutes he is able to work continuously for 3 minutes and rest for 7 minutes.

Rated operating voltage

The operation of a transformer welding device is based on reducing the input voltage value to the operating nominal value. When manufacturing a welding machine, you can make any value of the output parameters (30-80 V), which directly affects the range of operating electric currents. Unlike a 220 V power supply, the output value can be of the order of 1.5-2 Volts in products for spot electric welding. This is due to the need to obtain high level current

Mains voltage and number of phases

Current connection diagram for a welding transformer homemade type designed for connection to a household single-phase electrical network. For powerful welding devices, an industrial network with three phases of 380 V is used. The rest of the calculations are performed from the value of this input parameter. Do-it-yourself mini welding uses connection to the home electrical network and does not require high supply voltages.

Open circuit voltage

A household welder assembled by yourself must have a voltage level sufficient to ignite the electric arc. The higher this value, the easier it will appear. The manufacture of the device must comply with current safety regulations, which limit the output voltage to a maximum of 80 V.

Rated welding current of the transformer

Before you make an electric welding machine yourself, you need to decide on the size of the rated current. The ability to perform the work itself on metals of various thicknesses will depend on it. For household electric welding, a value of 200 A is quite sufficient, which allows you to make a fully functional device. Exceeding this indicator will require an increase in the power of the electrical transformer, which affects both the increase in its dimensions and weight.

Build process

The manufacture of a homemade electric welding machine begins with performing the necessary calculations. The values ​​of the input and output voltage, as well as the required amount of electric current, are taken into account. The size of the device and the quantity directly depend on this necessary materials. Electric welding machine, like other equipment, it is not very difficult to do it yourself. When calculated and used correctly quality components it can reliably serve for decades. For the base, a wire with copper wires, as well as a core made of magnetically permeable iron. The remaining components are not so essential and can be selected from those that can be easily obtained.

Where to start the preparatory stage

After completing the calculation part, materials are prepared and a workplace is equipped for assembling the structure. To build a homemade welding machine, you will need wires for the primary and secondary windings, for the core - suitable transformer iron, insulating materials (varnished fabric, textolite, glass tape, electrical cardboard). In addition, you should take care in advance about a winding machine for making windings, metal elements for the frame and an electrical switching device. During the assembly process, you will need a set of regular plumbing tools. Workplace choose a roomier one to freely wind the coils and engage in the assembly process.

Assembly of the structure

Having completed preparatory activities, proceed directly to the manufacture of the electrical apparatus. Homemade electric welding requires quite a lot of time during assembly. It is not so difficult as it is long and painstaking, requiring precise adherence to the calculated values. The procedure begins with the manufacture of a frame for the windings. For this, textolite plates of small thickness are used. The inside of the boxes should fit the transformer core with a small gap.

After assembling the two frames, it is necessary to insulate them to protect the electrical wire. This is done using any heat-resistant electrical insulating material (varnished cloth, glass tape or electrical cardboard).

A wire having heat-resistant insulation is wound onto the resulting frames. This will protect the product from possible breakdown due to overheating during operation. It is necessary to accurately count the number of turns so that there is no difference with the calculated values. Each wound layer is necessarily isolated from the next one. Reinforced insulation is laid between the primary and secondary winding layers. Do not forget to make the necessary bends on required quantities turns. After winding is completed, external insulation is performed.

At the next stage, the wound windings are mounted on the transformer core, and it is laminated (assembled into a single structure). In this case, it is undesirable to drill sheets of transformer iron during installation. Metal plates are connected to checkerboard pattern and fit well. Assembling a simple U-shaped welding machine with your own hands is not particularly difficult. At the end of the assembly procedure, the integrity of the windings is checked for possible damage. The final stage is assembling the housing and connecting the electrical switching device. Additional equipment includes a rectifier unit, as well as an electric current regulator.

Pay attention to all processes, from calculations to the assembly of homemade welding. The final parameters of the manufactured device will depend on this.

Due to the fact that ordinary people often need to work with metal in everyday life, many people use welding units. But not everyone can afford to purchase expensive equipment, which is why the question arises of how to assemble a welding machine with your own hands. The manufacturing process will differ depending on the type and design features welding device.

Types of Welding Machines

The modern market is filled with a fairly wide variety of welding machines, but not everything is advisable to assemble with your own hands.

Depending on the operating parameters of the devices, the following types of devices are distinguished:

• on alternating current– delivering alternating voltage from the power transformer directly to the welding electrodes;
• on DC– outstanding constant voltage at the output of the welding transformer;
• three-phase – connected to a three-phase network;
• inverter devices - delivering pulsed current to the work area.

The first version of the welding unit is the simplest; for the second, you will need to modify the classic transformer device with a rectifier unit and a smoothing filter. Three-phase welding machines are used in industry, so we will not consider the manufacture of such devices for domestic needs. An inverter or pulse transformer is a rather complex device, so to assemble a homemade inverter you must be able to read schematics and have basic skills in assembling electronic boards. Since the basis for creating welding equipment is a step-down transformer, we will consider the manufacturing order from the simplest to the more complex.

AC

Classic welding machines work on this principle: the voltage from the primary winding of 220 V is reduced to 50 - 60 V on the secondary winding and supplied to welding electrode with the workpiece.

Before you start making, select all the necessary elements:

• Magnetic core– stacked cores with a sheet thickness of 0.35 – 0.5 mm are considered more profitable, since they provide least losses in the iron of the welding machine. It is better to use a ready-made core made of transformer steel, since the tightness of the plates plays a fundamental role in the operation of the magnetic circuit.
• Wire for winding coils– the cross-section of the wires is selected depending on the magnitude of the currents flowing in them.
• Insulation materials– the main requirement for both sheet dielectrics and the native coating of wires is resistance to high temperatures. Otherwise, the insulation of the semi-automatic welding machine or transformer will melt and a short circuit will occur, which will lead to breakdown of the device.

The most profitable option is to assemble the unit from a factory transformer, in which both the magnetic core and the primary winding are suitable for you. But, if a suitable device is not at hand, you will have to make it yourself. You can familiarize yourself with the manufacturing principle, determining the cross-section and other parameters of a homemade transformer in the corresponding article:.

IN in this example We will consider the option of making a welding machine from a microwave power supply. It should be noted that transformer welding must have sufficient power; for our purposes, a welding machine with at least 4 - 5 kW is suitable. And since one transformer for a microwave oven has only 1 - 1.2 kW, we will use two transformers to create the device.

To do this you will need to perform the following sequence of actions:

Rice. 2: remove the high voltage winding

leaving only the low-voltage one, in this case there is no need to wind the primary coil, since you are using the factory one.

• Remove current shunts from the coil circuit on each transformer, this will increase the power of each winding.
  Rice. 3: Remove current shunts
• For the secondary coil, take a copper busbar with a cross-section of 10mm 2 and wind it on a pre-made frame from any available materials. The main thing is that the shape of the frame follows the dimensions of the core.
  Rice. 4: Wind the secondary winding onto the frame
• Make a dielectric gasket for the primary winding, any will do non-flammable material. Its length should be enough for both halves after connecting the magnetic circuit.
  Rice. 5: Make a dielectric pad
• Place the power coil in the magnetic circuit. To fix both halves of the core, you can use glue or tighten them together with any dielectric material.
  Rice. 6: Place the coil in the magnetic circuit
• Connect the primary terminals to the power cord, and the secondary terminals to the welding cables.
  Rice. 7: Connect the power cord and cables

Install a holder and an electrode with a diameter of 4 - 5 mm on the cable. The diameter of the electrodes is selected depending on the strength of the electric current in the secondary winding of the welding machine; in our example, it is 140 - 200A. With other operating parameters, the characteristics of the electrodes change accordingly.

The secondary winding has 54 turns; to be able to adjust the voltage at the output of the device, make two taps from 40 and 47 turns. This will allow the current in the secondary to be adjusted by reducing or increasing the number of turns. A resistor can perform the same function, but only to a lower value than the nominal value.

DC

This device differs from the previous one in the more stable characteristics of the electric arc, since it is obtained not directly from the secondary winding of the transformer, but from a semiconductor converter with a smoothing element.

Rice. 8: Rectification circuit diagram for welding transformer

As you can see, you don’t need to wind the transformer for this, just modify the circuit existing device. Thanks to this, it will be able to produce a more even seam and cook stainless steel and cast iron. To make it, you will need four powerful diodes or thyristors, approximately 200 A each, two capacitors with a capacity of 15,000 uF and a choke. The connection diagram for the smoothing device is shown in the figure below:

Rice. 9: connection diagram of the smoothing device

Revision process electrical diagram consists of the following stages:

Due to overheating of the transformer during operation, the diodes can quickly fail, so they need forced heat removal.

It is better to use tinned clamps for connection, as they will not lose their original conductivity due to high currents and constant vibration.

Rice. 12: Use tinned clamps

The thickness of the wire is selected in accordance with the operating current of the secondary winding.

When welding metals with such a device, you should always control the heating of not only the transformer, but also the rectifier. And upon reaching critical temperature pause to allow the elements to cool, otherwise the homemade welding unit will quickly fail.

Inverter device

It is a rather complex device for beginner radio amateurs. An equally complex process is the selection necessary elements. The advantage of such a welding machine is its significantly smaller dimensions and lower power, in comparison with classical devices, the ability to implement, etc.

Rice. 14: schematic diagram of the pulse block

In operation, such a circuit converts alternating voltage from the network to direct voltage, then, using a pulse unit, produces a high-amplitude current into the welding area. This achieves a relative saving in the power of the device in relation to its productivity.

Structurally, the inverter circuit of the welding machine includes the following elements:

• diode rectifier with a capacitor magazine, a ballast resistor and a soft start system;
• control system based on a driver and two transistors;
• power section consisting of a control transistor and an output transformer;
• output part of diodes and inductor;
• cooling system from a cooler;
• system feedback by current to control the parameter at the output of the welding machine.

You will need to wind it yourself power transformer, current transformer based on a ferrite ring. For the bridge, it is better to use a ready-made assembly of high-speed semiconductor elements.

Unfortunately, most other items are unlikely to be on hand in the garage or at home, so they will have to be ordered or purchased from specialized stores. Because of this, assembling an inverter unit with your own hands will cost no less than the factory version, but taking into account the time spent, even more expensive. Therefore for inverter welding It is better to purchase a ready-made device with specified operating parameters.

Video instructions