When performing simple and small-scale welding work at home, anyone can assemble.

You don’t have to spend a lot of money, effort and time to assemble. There is also no need to purchase unreasonably expensive models of such equipment.

To make a mini welding machine with your own hands from available materials, without special financial costs and effort, you need to understand how the equipment functions, after which you can start producing it at home.

First of all, it is worth determining the required power supply for homemade welding equipment. Connecting parts of a massive structure requires a higher current intensity, and welding work with thin metal surfaces requires minimal current.

The current value is related to the selected electrodes that will be used in the process. When welding products up to 5 millimeters, it is necessary to use rods up to 4 millimeters, and in a structure with 2 millimeters thick, rods should be 1.5 millimeters.

When using electrodes of 4 millimeters, the current is regulated up to 200 amperes, for 3 millimeters up to 140 amperes, for 2 millimeters - up to 70 amperes, and for the smallest ones up to 1.5 millimeters - up to 40 amperes.

You can form an arc for the welding process yourself using mains voltage, which is obtained due to the operation of the transformer.

This equipment includes:

• magnetic circuit;
• winding – primary and secondary.

You can also make a transformer yourself. For the magnetic circuit, plates made of steel or other durable material are used. Windings are necessary to directly perform welding work and to be able to connect the welding unit to a 220 volt network.

Transformer for welding work.

Specialized equipment has additional devices that improve the quality and power of the arc, which makes it possible to independently regulate the current values.

There is no need to go deep enough into this topic, since one of the easiest ways to assemble a welding machine with your own hands is.

Its feature is that it works with alternating current, which ensures a high-quality seam when welding metal surfaces. Such equipment can cope with any household work where it is necessary to weld metal or steel structures.

To make it you need to prepare:

1. Several meters of cable with great thickness.
2. Material for the core that will be located in the transformer.
   The material itself must have increased permeability with magnetization.

The best option is when the rod-shaped core has the letter “P”. In some cases, it is allowed to use this part in a more modified form, for example, a round stator made from a damaged electric motor.

Diagram of a welding transformer.

However, it is worth paying attention that it is more difficult to wind windings onto this shape. It is best when the core cross-section for a classic welding equipment, made by hand and used for domestic purposes, had an area of ​​about 50 cm2.

In order for the equipment to have an accessible weight, it is not necessary to increase the cross-section in volume, however, the technical effect will not be top level. If the cross-sectional area does not suit you, then you can calculate it yourself using special diagrams and formulas.

The primary winding must be made of copper wire, which will have increased characteristics: thermal resistance, since during operation of the structure this part heats up very much.

Such a part must have cotton or fiberglass insulation. As a last resort, it is possible to use rubber insulated wire or rubber cloth, but beware of PVC winding.

The insulation is also made by hand, using cotton or fiberglass, or rather parts of it 2 cm wide. Thanks to these pieces, you can wrap the wire and then impregnate it with any varnish for electrical purposes. This insulation will not overheat after regular use.

Similar to the above calculations, it will be possible to calculate which cross-sectional area of ​​the winding - primary and secondary - will be the most optimal. Often the secondary winding has an area of ​​about 30 mm2, and the primary winding up to 7 mm2, using a rod of 4 millimeters in diameter.

Besides in a simple way you need to determine how far a piece of copper wire will stretch and how many turns will be needed to wind two windings. After this, the coils are wound, and the frame is made using the geometric parameters of the magnetic core.

The main thing is to ensure that there are no difficulties when putting on the magnetic core. First of all, you need to choose the correct core size. It is best made using electrical cardboard or textolite.

Using the same analogue, it will be possible to make a structure for welding small parts. For home use, you can use a small mini welding machine.

Manufacturing of welding machine

Today it is almost impossible and quite difficult to weld metal or process it in the proper way without using welding equipment. After you make a welding machine with your own hands, you will be able to perform any work with metal products.

Transformer circuit with a separate choke.

To produce a high-quality unit, you must have knowledge and skills that will help you understand the circuit of a DC or AC welding machine, which are two options for assembling equipment.

For home use, it is best to learn how to make mini welding.

It is more convenient to call a specialist or purchase a ready-made unit, but sometimes this can be too expensive, since it is quite difficult to determine the choice of model based on various parameters, such as the weight of the welding machine, and the number of volts per welding machine.

There are several types of welding machines: operating on alternating current, direct current, having three phases or inverter. To choose one of the options and start assembling, you need to consider each circuit of the first 2 types. During the preparatory process, you need to pay attention to the voltage stabilizer.

AC

To make homemade welders it is necessary to select a voltage indicator, the best is 60 volts, the current is best adjusted from 120 to 160 amperes.

You can independently determine the cross-sectional value of the required wire for the manufacture of the primary winding of the transformer, which must be connected to a 220-volt network.

The cross-section according to the area parameters should not be more than 7 mm2, since it is worth noting the possible voltage drop and possible additional load.

Based on the calculations, optimal size The diameter of the copper core for the primary winding, which reduces the action of the mechanism, is 3 millimeters. When choosing aluminum for the wire, the cross-section is multiplied by 1.6.

It is worth noting that the wires need to be wrapped with a rag, since they must be insulated. The fact is that when the temperature increases, the wire can melt and a short circuit may occur.

If the necessary wire is not available, it is possible to replace it with a slightly thinner wire, winding it in pairs. However, it must be remembered that the thickness of the winding will increase, which is why the dimensions of the welding equipment will be larger. For the secondary winding, a thick wire with a large number of copper cores is used.

DC

Electrical circuit of the welder on DC.

Some welding machines operate using direct current. Thanks to this unit, you can weld cast iron products and stainless steel structures.

It may take no more than half an hour to create a DC welding machine with your own hands. In order to convert a homemade product with alternating current, it is necessary that the secondary winding be connected, which is assembled on a diode.

In turn, the diode must withstand a current of 200 amperes and have good cooling. To equalize the current value, you can use capacitors that have certain characteristics and voltage characteristics. After this, the unit is assembled sequentially according to the scheme.

Chokes are used to regulate current, and contacts are used to attach a holder. Additional parts are used to transmit current from an external carrier to the welding site.

In order to operate the welding machine for its intended purpose, it is necessary, first of all, to ignite the electric arc. This process is easy and is carried out by the following steps: we bring the tip of the electrode at a certain angle from the side of the metal coating and scratch it along the surface of the structure.

If the action is performed correctly and successfully, a small flash occurs and the material melts, after which the necessary elements can be welded.

When making a mini welding machine with your own hands, you must follow the recommendations for working with it. To weld elements, you need to hold the rod in such a position that it is at a certain distance from each other of the parts being welded. This distance can be equal to the cross-section of the selected electrode.

Often a metal such as carbon steel is connected with direct polar current. However, some alloys can only be welded using reverse current polarity. In addition, it is necessary to carefully monitor the quality of the seam and how the structure is fused.

Diagram of a simple welding machine.

It is worth emphasizing that the alternating current located can be regulated efficiently and smoothly. Often, no difficulties arise in setting up the unit to the required parameters.

With a small current indicator, the seam will turn out to be of poor quality, but you should not set an increased value, since there is a risk of burning the surface.

If it is necessary to weld surfaces of small thickness, then the rods are suitable with a size of 1 to 3 millimeters, and the current strength should vary from 20-60 A. Using large cross-section electrodes, you can weld metal products up to 5 millimeters, but in this case the current should be 100 A.

Upon completion of the welding process, using a homemade product, it is necessary to carefully remove the scale that appears on the seam with light movements, after which it is cleaned with a special brush.

Thanks to this action, you can maintain a pleasant aesthetic appearance of your device. Don’t worry if cleaning the equipment isn’t very successful in the first couple of days. This skill is developed through experience and subject to following all recommendations for proper operation of the structure.

Bottom line

To summarize, it is worth noting that DC welding machines are much easier to assemble and they are also easy to use, due to their low power.

At the moment, there are several modifications of various welding machines. Do-it-yourself welding transformers can be made quite easily if you have certain skills.

The most popular are transformer welding, designed for contact and arc welding metal structures. The popularity of this type of welding transformer is due to several reasons:

• simplicity and reliability of the device;
• the presence of a wide range of uses of this type of equipment;
• presence of high mobility.

In addition to the listed advantages, the use of this type of device has a number of disadvantages, the main ones being the following:

• low efficiency of the transformer apparatus;
• high dependence of the quality of the seam on the skills of the welder.

For installation, you can make a transformer with your own hands. The device is a unit that increases the current while simultaneously decreasing its voltage.

Manufacturing technology of a transformer for a welding machine

Various welding transformer circuits have been developed. The unit equipped with a U-shaped magnetic core configuration has gained the most popularity. If there is a U-shaped magnetic core, winding the wire of the primary and secondary windings is quite simple. U-shaped devices are easily disassembled if repairs are necessary. To create a welding machine, you need to know the operating principle of a welding transformer.

In order to operate the device in household needs oh, you need to put such coils on the core that would allow you to weld metal workpieces with electrodes having a diameter of 3-4 mm. When creating a unit, it is necessary to calculate the welding transformer. When manufacturing a unit for a welding device, you need to assemble a magnetic core. When assembling the core, remember that the cross-section should be at least 25-35 cm². Calculation of the welding transformer, in particular, the required cross-sectional area, is carried out according to the formula S=a*b, cm².

After the calculation and manufacture of the core, a wire is selected for the manufacture of windings. When choosing an electrical conductor, special attention is paid to its cross-section and overall length. To make the primary winding coil, it is best to use a special winding heat-resistant wire made of copper, coated with cotton or fiberglass insulating material. It is advisable that copper wire had a square or rectangular cross-section.

If there is a wire of the required cross-section and there is no required insulating material you can make it yourself. For this purpose, several narrow strips of cotton or fiberglass material are prepared. The width of the strip should be 2 cm. After making the strips of insulating material, it is used to wind the copper wire. The wrapped wire is impregnated with electrical varnish.

In order for the welding machine to be able to weld metal workpieces well, it is necessary to ensure a normal level of alternating current voltage without load.

At idle speed, this parameter should be equal to 60-65 V. When carrying out welding work, the voltage should be in the range of 18-24 V, depending on the diameter of the electrode.

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Features of calculating transformer parameters for a welding device

In preparation for the manufacture of a transformer, it is necessary to calculate several technical parameters of the equipment, on which the normal operation of the welding installation completely depends. The main parameters requiring calculations are the following:

• cross-sectional area of ​​the core;
• cross-sectional area of ​​the primary winding wire;
• cross-sectional area of ​​the secondary winding wire.

When making calculations, it is imperative to take into account the maximum power that the welding unit will have. For example, with a power consumption of 5 kW, the cross-sectional area of ​​the primary winding wire should be about 5 mm². When making a winding the best option will be if the cross-sectional area is 6-7 mm². With the specified parameters for the power consumption of the primary winding and its cross-section, the secondary winding must have a cross-section of 30 mm² (excluding insulating material).

Before winding coils onto a core, it is necessary to calculate not only the number of turns, but also the length of the wire. The primary winding must have a voltage that is lower than that household network. In order to lower the voltage by the appropriate value, it is necessary to calculate the number of turns per 1 volt of voltage for this purpose. The formula used is n=48/Sm, where Sm is the cross-sectional area of ​​the core, expressed in square centimeters.

With a good, high-quality magnetic circuit n=0.9-1. Based on this, the total number of turns of the coil is determined in accordance with the formula W1=U1/n, therefore, with optimal performance of the magnetic circuit, about 200-300 turns are obtained, depending on the cross-section of the magnetic circuit. Depending on the number of turns, the length of the copper wire is selected. The secondary winding indicators are calculated in a similar way.

Due to the fact that in everyday life people often need to work with metal, 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 - outstanding AC voltage from the power transformer directly to the welding electrodes;
• on direct current - outstanding constant pressure at the output of the welding transformer;
• three-phase – connected to a three-phase network;
• inverter devices - outstanding impulse 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. Inverter or pulse transformer quite a complex device, so to assemble homemade inverter you must be able to read schematics and have basic electronic circuit board assembly skills. 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 operate on this principle: the voltage from the primary winding of 220 V is reduced to 50 - 60 V on the secondary winding and is supplied to the 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 the 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 home-made transformer in the corresponding article:.

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 non-flammable material will do. 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 more stable characteristics 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 when the critical temperature is reached, pause to cool the elements, otherwise the welding unit made by yourself will quickly fail.

Inverter device

It is a rather complex device for beginner radio amateurs. An equally complex process is the selection of the 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: circuit diagram 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;
• current feedback system for monitoring 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 of the 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

If you have the necessary plumbing and electrical installation tools (we will talk about them in detail below), and you have the appropriate professional skills, then you can quite make it DIY welding transformer.

You will, of course, have expenses, but they will be incomparably lower compared to the costs of purchasing a factory-made gadget. But how much pleasure you will get in the process of your favorite homemade work. And the delight at the moment of successful start of electric welding is, in general, incomparable!

In this article we will give you a lot useful tips by selection, calculation and production welding transformer (hereinafter – ST), which will help you optimize costs and save your budget.

A properly made device with your own hands is no worse than a factory one.

The article will talk about two types of welding transformers. For welding:

• arc;
• contact

DIY welding transformer: what we need

The range of tools and equipment for the manufacture and assembly of both types of ST is identical. We will need the following:

• electrical voltage indicator. To control the absence of the latter on electrical contacts, and thereby ensure safety when performing electrical installation work;
• angle grinder(aka “grinder”, “zip-machine”, etc.) with a set of discs (cutting, grinding, etc.);
• electric drill with a set of metal drills and a core;
• tester or voltmeter alternating current with a measurement limit of 400 V;
• any " scriber" Used when marking on metal;
• locksmith clamps. For fixing parts when marking “in place”;
• set of electric tools. The specific composition of the kit depends on the materials that will be used in the manufacture of the ST. In general it is like this:
  • Complete electric soldering iron. We will perform soldering with POS-40 solder;
  • screwdrivers (various sizes with straight and Phillips slots);
  • keys:
    • nuts;
    • caps;
    • end;
  • pliers, side cutters, etc. with insulated handles;
• set of files.

It is more convenient to carry out all work on a bench with an electrical insulating coating, equipped with a bench vice.

To manufacture a transformer, components and materials are required that differ depending on the type of transformer. In general, the following is required:

• protective cover. Must provide:
  • protection against electric shock;
  • exclude the possibility of any objects getting inside the gadget;
• magnetic circuit. Provides a powerful electromagnetic flux, which induces electromotive force (hereinafter referred to as EMF) in the windings;
• wire and wire. Necessary for installation of windings;
• reel frames. Windings are wound on them;
• contact blocks. Powerful terminal block with clamps for welding wires, small terminal blocks for wiring the circuit;
• switches (switches). Switch winding sections when selecting the welding current value;
• material for interturn insulation. Reduces the possibility of electrical breakdown of winding insulation;
• fasteners (bolts, screws, nuts, washers, etc.). They are necessary for installing the gadget during assembly work;
• insulation tape(cotton type).

Important: PVC insulating tape cannot be used, because it is destroyed when heated.

Homemade welding transformer for arc welding

Before you begin further work on the manufacture of CT, you should decide what exactly you will create. You need:

• choose design and electrical schematic diagram future device;
• carry out electrical and, if necessary, structural calculations of its parameters.

Only after this should you select the necessary equipment, materials and prepare, if necessary, special tools.

How to calculate a welding transformer. Scheme

The question of how to calculate a homemade welding transformer is very specific, since it does not correspond to standard diagrams and generally accepted rules. The fact is that when making homemade products, the parameters of their components are “adjusted” to the components already available (mainly to the magnetic circuit). Moreover, it often happens that:

• transformers are not assembled from the best transformer iron;
• the windings are wound with not the most suitable wire and many other negative factors.

As a result, homemade products heat up and “hum” (the core plates vibrate at the frequency of the mains: 50 Hz), but at the same time they “do their job” - weld metal.

Based on the shape of the cores, transformers are classified into the following main types:

• core;
• armored.

Explanations for the picture:

• a – armored;
• b – rod.

Transformers core type, compared to transformers armored type, allow high current densities in the windings. Thanks to this, they have a higher efficiency, but the labor intensity of their production is much higher. However, they are used more often.

On the rod core, the winding circuits shown in the figure are used.

Explanations for the picture:

• 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;
• g – the corresponding secondary winding, connected in series.

For example, let’s calculate the ST assembled according to the scheme “c” - “d”. Its secondary winding consists of two equal parts (halves). They are located on opposite shoulders of the magnetic circuit, and are connected to each other in series. Calculations consist of determining the theoretical and selecting the actual dimensions of the magnetic circuit.

We determine the CT power (based on the current in the secondary winding) from the following considerations. For electric welding in everyday life, coated electrodes Ø, mm: 2, 3, 4 are most often used. We choose the “golden mean” for the most popular ones - 120...130 A. CT power is determined by the formula:

P = Uх.х. × Ist. × cos(φ) / η, where:

• Uх.х. — open circuit voltage;
• Ist. — welding current;
• φ is the phase angle between voltage and current. We accept: cos(φ) = 0.8;
• η - efficiency. For homemade ST: efficiency = 0.7.

If you calculate the magnetic core according to the reference book, then its cross-section for the selected current is 28 sq.cm. In practice, the cross-section of the magnetic circuit for the same power can vary within the range: 25...60 sq.cm.

For each section, it is necessary to determine (using a reference book) the number of turns of the primary winding to ensure the specified output power. We will only note that the larger the cross-sectional area of ​​the magnetic circuit (S), the fewer turns of both coils will be needed. This is an important point, since a large number of turns may not fit into the “window” of the magnetic circuit.

It is possible to use the magnetic core of an old transformer (for example, from microwave oven, of course, after some reconstruction - replacement of the secondary winding).

If you do not have an old transformer, then you should purchase transformer iron from which you will make the CT core.

Explanations for the picture:

• a – L-shaped plates;
• b – U-shaped plates;
• c – plates made of transformer steel strips;
• c and d – dimensions of the “window”, cm;
• S = a x b – cross-sectional area of ​​the core (yoke), sq. cm.

Calculation of the number of turns of the primary windings at a supply voltage of 220...240 V, welding currents selected by us and magnetic circuit parameters can be made using the following formulas:
N1 = 7440 × U1/(Sfrom × I2). For windings on one arm (half of the winding on top of each other, connected in series);
N1 = 4960 × U1/(Sfrom × I2). The windings are spaced on different arms.

Conventions in both formulas:

• U1 – power supply voltage;
• N1 - number of turns of the primary winding;
• Siz - cross-section of the magnetic circuit (sq. cm);
• I2 is the specified welding current of the secondary winding (A).

Output voltage The secondary winding of the CT in the idle mode of homemade welding transformers is, as a rule, within the range of 45...50V. Using the following formula you can determine its number of turns:
U1/U2 = N1/N2.

For the convenience of selecting the strength of the welding current, taps are made on the windings.

Winding the welding transformer and installation

For the primary winding of the transformer, a special heat-resistant copper wire with cotton or fiberglass insulation is used.

Taking into account the power selected above, electricity in the primary winding can reach 25 A. Based on these considerations, the primary winding of the CT should be wound with a wire having a cross-section of ≥ 5...6 sq.mm. This, among other things, will significantly increase the reliability of the ST.

The secondary winding is carried out copper wire, the cross-section of which is: 30…35 sq.mm. Particular attention should be paid to the choice of insulation of the secondary winding wire, since a large welding current flows through it. It must be very reliable - special attention should be paid to heat resistance.

When installing the windings, pay attention to the following:

• winding is carried out in one direction;
• An insulating layer of additional insulation is laid between the rows of windings (we recommend cotton).

The assembled CT should be placed in a protective casing with holes for ventilation.

Video

See how the task of assembling the device was implemented:

Do-it-yourself resistance welding from a welding transformer

Contact welding creates a welded connection between parts due to the following simultaneous effects on them:

• heating the area of ​​their contact with an electric current passing through it;
• a compressive force is applied to the joint area.

There are three types of resistance welding:

• point;
• butt;
• suture

We will tell you about a homemade CT for the most popular: resistance spot welding (the other two require very complex equipment).

Explanations for the picture:
1 – electrodes supplying welding current to the products being welded;
2 – welded products with an overlap connection;
3 – welding transformer.

To carry out contact welding, depending on the thickness and thermal conductivity of the materials of the parts being welded, the following values ​​of its main parameters are selected:

• electrical voltage in the power (welding circuit), V: 1…10;
• welding current value (welding pulse amplitude), A: ≥ 1000;
• heating time (passage of the welding current pulse), sec: 0.01…3.0;

In addition, the following must be provided:

• minor melting zone;
• significant compressive force applied to the welding site.

Scheme and calculation

Calculation of CT resistance welding is performed using the same algorithm as for arc welding (see above). When selecting data from the directory (current strength and voltage of the secondary winding for spot welding selected grade of metal of a given thickness), it should be taken into account that the current strength of the secondary winding for such transformers is about 1000...5000 A. The secondary winding is designed, as a rule, for units of volts and consists of only a few turns (sometimes one) of thick wire. Therefore, to adjust the welding current, the following diagram of the primary winding of the transformer is recommended.

Very often, during the operation of home-made products, it turns out that there is not enough power of the ST. In this case, it is possible to connect a second transformer in accordance with the proposed circuit.

Winding and installation

These operations are performed according to the same basic rules and in compliance with the requirements as for CT arc welding. The turns of the secondary winding should be secured with special care. To do this, you can use its leads by passing them through a heat-resistant insulator.

Copper rods are used as electrodes.

Should be considered that the larger the diameter of the electrode, the better. Under no circumstances should the diameter of the electrode be smaller than the diameter of the wire. For low-power STs, it is possible to use tips from powerful soldering irons.

During operation, monitor the condition of consumables: the electrodes must be periodically sharpened - otherwise they will lose their shape. Over time, they wear down completely and require replacement.

:

• the welder needs to stand on a rubber mat;
• the worker must have rubber gloves on his hands;
• A welding helmet is not required, but safety glasses must be worn on the face.

conclusions

We have given you enough information to make a homemade welding transformer:

• arc welding;
• resistance welding.

Do-it-yourself welding machines for the home are most often created by craftsmen from scrap materials.

If you do not have the opportunity or desire to buy a welding machine, then you can assemble it yourself using ready-made elements.

However, to speed up the assembly process, ready-made components and parts can be used. The holder for electrodes can also be made on your own from those available in the arsenal home handyman materials.

The simplest welding machine

In a home craftsman's household, you may find a step-down transformer S-B22, IV-10, IV-8, the power of which is 1-2 kW. It reduces the voltage from 220 V to 36 V and serves to power power tools.

Welding machines based on such transformers can be assembled even with a failed winding.

The welding machine is manufactured as follows:

The secondary winding must be removed from the transformer.

• secondary windings are removed from the coils without damaging the primary ones;
• the middle primary coil is rewound with the same wire, creating taps with a total number of 8-10 pieces after 30 turns. (for convenience, it is better to number each of them as they are created);
• the two outer coils are filled with a multi-core cable (three 6-8 mm wires with a thin phase, 12-13 m are consumed for each coil);
• a copper pipe with a diameter of 10-12 mm is used for the terminal for the VO cable (one side crimps the wires, the other is flattened, drilled for fasteners with a diameter of 10 mm);
• on the top panel of the transformer, the M6 ​​fasteners are replaced with a more powerful one (M10), and the VO terminals are attached to them;
• A board with 10 holes for software is made from PCB, and an M6 fastener is inserted into each hole.

Welding machines of this design are powered by a 380/220 V network. In the first case, the outer coils are connected in series, then the middle coils. In the second option, the outer windings are connected in parallel, the middle one is connected in series to the same circuit. The VO taps are placed in the terminals of the textolite plate 1 - 10. The current is regulated by terminals 1 - 10.

It is not recommended to carry out large volumes of work with this SA (maximum 15 “troika” electrodes).

To cut metal, the second end of the cable leading to the holder is connected to the cutting terminal (on the side of the middle PO coil). The characteristics of the VO current correspond to 60-120 A, in the software the current is always 25 A. When working with “two” electrodes, the transformer does not heat up above +70˚C, so the operating time is not limited. Welding/cutting modes are switched when the switch is turned off.

At idle speed, this parameter should be equal to 60-65 V. When carrying out welding work, the voltage should be in the range of 18-24 V, depending on the diameter of the electrode.

Machine for welding from car batteries

In order to invent a diesel generator for a welding machine, it is necessary to connect a pair of batteries in a certain sequence.

The welding machine seriously loads the household electrical network, providing a voltage surge of 30 V at a load of 3.5 kW. Instead of purchasing a welding diesel generator, the craftsmen created an original device circuit, the basis of which is 3-4 series-connected batteries from a passenger car. The capacity of each of them must be at least 55-190 A/h; reliable clamps must be used to combine them into a common circuit.

This scheme is indispensable in field conditions, since even used batteries delivered to the site by a passenger vehicle will help out. It is necessary to take into account the strong heating of battery cases after several hours of operation, check the level and density of the electrolyte daily with constant use. In hot weather, water evaporates rapidly from the electrolyte, so control devices (hydrometer), distilled water, and acid should be kept at hand.

Welding machines of this type simply need to be charged at night by connecting the appropriate device to a common circuit so that all batteries are charged at once. When welding with electrodes with a diameter of 3 mm, the working current is no more than 90-120 A, which does not exceed half the power. The electrolyte does not boil due to its high heat capacity. The output voltage depends entirely on the number of batteries connected to the circuit and is 42-54 V.

At idle speed, this parameter should be equal to 60-65 V. When carrying out welding work, the voltage should be in the range of 18-24 V, depending on the diameter of the electrode.

Homemade toroidal welding machine

U-shaped and W-shaped transformers are significantly inferior to toroids in terms of weight and size. A toroidal welding machine is one and a half times lighter than its W-shaped counterpart, but the main difficulty in self-production lies in the lack of necessary iron. Craftsmen share recommendations for making a transformer from an industrial CA that has exhausted its service life. A similar replacement would be the TCA 310 or TS 270 transformer. Its U-shaped plates are “halved” with a chisel and adjusted on an anvil.

Welding machines of this type are assembled from 45 x 9 cm plates:

• a plate riveted hoop with a diameter of 26 cm is filled with plates end to end (the work is done by two people, a partner fixes the core being assembled, preventing the plates from straightening);
• when the internal diameter of the structure reaches 12 cm, the set stops;
• Details are cut out of electrical cardboard: a strip 9 cm wide, rings with an internal diameter of 11 cm, an external diameter of 27 cm;
• the rings are applied to the sides of the structure assembled at the first stage and wrapped with fabric tape;
• winding I is laid on electrical tape - 170 turns (for 220 V) of wire with a diameter of 2 mm, grade PEV-2;
• winding II is laid on top of it - 30 turns of wire with a diameter of 15-20 mm, grade PEV-3;
• winding III - 30 turns with MGTF 0.35 wire;
• insulation from each other with tape, the software is checked for the XX current: if it is less than 1-2 A, several turns are unwound; if the XX current is greater than 2 A, two turns are added.

This welding machine has an original control circuit in the form of a phase regulator. The voltage removed from winding III is rectified by a diode bridge. The capacitor is charged through resistors up to 6 V, then a breakdown occurs through a dinistor assembled from a thyristor and a zener diode. The diode with the thyristor opens. The last resistor in the circuit limits the current; when the alternating current wave is negative, the response thyristor and diode open. Welding machines of this design are tuned with a resistor.

To create a welding machine, resistors with a power of 10 W or more are required.

The scheme uses:

• diodes for a current of 160-250 A, mounted on radiators with an area of ​​100 cm2;
• capacitor K50-6;
• resistors with a power of 10 W;
• thyristors KU202 or KU201.

The welding machine confidently welds with electrodes with a diameter of 4 mm and cuts metal. You can make a holder for it yourself from an equal angle corner 10 cm long (shelves 2 cm each). A hole with a diameter of 4.1 mm is drilled 1 cm from the edge of the corner in the very corner, through which the burnt electrode can be pushed out with a new electrode. The lower part of the shelves will be narrowed according to the welder's hand. A wire is welded into the inner corner, bent vertically upward from it. A piece of rubber hose is placed on the structure from below. During operation, the electrode is inserted between the edges of the angle and pressed against them with a piece of welded wire.