The simplest machines for electric arc welding with your own hands. Construction of homemade DC welding machines

Figure 1. Diagram of a bridge rectifier for a welding machine.

Welding machines come in direct and alternating current.

S.A. direct current are used for low current welding of thin sheet metal (roofing steel, automotive, etc.). The DC welding arc is more stable; direct and reverse polarity welding is possible. You can weld on direct current using electrode wire without coating and electrodes designed for welding on both direct current and alternating current. To make the arc burning stable at low currents, it is desirable to have an increased open-circuit voltage Uxx of the welding winding (up to 70 - 75 V). To rectify alternating current, the simplest “bridge” rectifiers on powerful diodes with cooling radiators are used (Fig. 1).

To smooth out voltage ripples, one of the outputs of S.A. And they are connected to the electrode holder through inductor L1, which is a coil of 10 - 15 turns of a copper bus with a cross section of S = 35 mm 2, wound on any core, for example, from. To rectify and smoothly regulate the welding current, more complex circuits are used using powerful controlled thyristors. One of the possible circuits based on thyristors of type T161 (T160) is given in the article by A. Chernov “It will charge and weld” (Model Designer, 1994, No. 9). The advantages of DC regulators are their versatility. The range of their voltage changes is 0.1-0.9 Uxx, which allows them to be used not only for smooth adjustment of welding current, but also for charging batteries, powering electric heating elements and other purposes.

Figure 2. Diagram of the falling external characteristic of the welding machine.

Rice. 1. Bridge rectifier for welding machine. Connection shown S.A. for welding thin sheet metal with “reverse” polarity - “+” on the electrode, “-” on the part being welded U2: - output alternating voltage of the welding machine

AC welding machines are used when welding with electrodes whose diameter is more than 1.6 - 2 mm, and the thickness of the welded products is more than 1.5 mm. In this case, the welding current is significant (tens of amperes) and the arc burns quite steadily. Electrodes designed for welding with alternating current only are used. For normal operation of the welding machine it is necessary:

1. Provide output voltage for reliable arc ignition. For amateur S.A. Uxx = 60 - 65v. A higher open circuit output voltage is not recommended, which is mainly due to ensuring operational safety (Uxxindustrial welding machines - up to 70 - 75 V).
2. Provide the welding voltage Usv necessary for stable arc burning. Depending on the diameter of the electrode - Usv = 18 - 24 V.
3. Provide rated welding current Iw = (30 - 40) de, where Iw is the value of the welding current, A; 30 - 40 - coefficient depending on the type and diameter of the electrode; dе - electrode diameter, mm.
4. Limit the short circuit current Isk, the value of which should not exceed the rated welding current by more than 30 - 35%.

Stable arc burning is possible if the welding machine has a falling external characteristic, which determines the relationship between the current strength and voltage in the welding circuit (Fig. 2).

S.A. shows that for rough (stepwise) overlap of the range of welding currents, switching of both primary and secondary windings is necessary (which is structurally more difficult due to the large current flowing in it). In addition, to smoothly change the welding current within the selected range, mechanical devices for moving the windings are used. When the welding winding is removed relative to the network winding, the magnetic dissipation fluxes increase, which leads to a decrease in the welding current.

Figure 3. Diagram of a rod-type magnetic circuit.

When designing an amateur SA, one should not strive to completely cover the range of welding currents. It is advisable at the first stage to assemble a welding machine for working with electrodes with a diameter of 2 - 4 mm, and at the second stage, if it is necessary to work at low welding currents, supplement it with a separate rectifier device with smooth control of the welding current. Amateur welding machines must satisfy a number of requirements, the main of which are the following: relative compactness and low weight; sufficient operating time (at least 5 - 7 electrodes dе = 3 - 4 mm) from a 220V network.

The weight and dimensions of the device can be reduced by reducing its power, and the operating time can be increased by using steel with high magnetic permeability and heat-resistant insulation of the winding wires. These requirements are easy to meet if you know the basics of welding machine design and adhere to the proposed technology for their manufacture.

Rice. 2. Falling external characteristic of the welding machine: 1 - family of characteristics for different welding ranges; Isv2, Isvz, Isv4 - ranges of welding currents for electrodes with a diameter of 2, 3 and 4 mm, respectively; Uxx - CA open circuit voltage. Is - short circuit current; Ucv - welding voltage range (18 - 24 V).

Rice. 3. Rod-type magnetic core: a - L-shaped plates; b - U-shaped plates; c - plates made of transformer steel strips; S = axb - cross-sectional area of ​​the core (core), cm 2 s, d - window dimensions, cm.

So, choosing the type of core. For the manufacture of welding machines, rod-type magnetic cores are mainly used, since their design is more technologically advanced. The core is made from electrical steel plates of any configuration with a thickness of 0.35-0.55 mm, tightened with pins insulated from the core (Fig. 3). When selecting a core, it is necessary to take into account the dimensions of the “window” to fit the windings of the welding machine, and the cross-sectional area of ​​the core (core) S =axb, cm 2. As practice shows, you should not choose the minimum values ​​of S = 25 - 35 cm, since the welding machine will not have the required power reserve and it will be difficult to obtain high-quality welding. And overheating of the welding machine after short-term operation is also inevitable.

Figure 4. Diagram of a toroidal magnetic circuit.

The cross section of the core should be S = 45 - 55 cm 2. The welding machine will be somewhat heavier, but it will not let you down! Amateur welding machines on toroidal-type cores, which have higher electrical characteristics, are about 4 to 5 times higher than those of a rod type, and electrical losses are low, are becoming increasingly widespread. The labor costs for their manufacture are more significant and are associated primarily with the placement of the windings on the torus and the complexity of the winding itself.

However, with the right approach they give good results. The cores are made from transformer strip iron, rolled into a torus-shaped roll. An example is a core from a 9 A “Latr” autotransformer. To increase the internal diameter of the torus (“window”), a piece of steel tape is unwinded from the inside and wound onto the outside of the core. But, as practice shows, Latra alone is not enough to produce high-quality SA. (small section S). Even after working with 1 - 2 electrodes with a diameter of 3 mm, it overheats. It is possible to use two similar cores according to the scheme described in B. Sokolov’s article “Welding Baby” (Sam, 1993, No. 1), or to produce one core by rewinding two (Fig. 4).

Rice. 4. Toroidal magnetic core: 1.2 - autotransformer core before and after rewinding; 3 design S.A. based on two toroidal cores; W1 1 W1 2 - network windings connected in parallel; W 2 - welding winding; S = axb - cross-sectional area of ​​the core, cm 2, s, d - internal and external diameters of the torus, cm; 4 - electrical diagram S.A. based on two joined toroidal cores.

Amateur SAs made on the basis of stators of high-power asynchronous three-phase electric motors (more than 10 kW) deserve special attention. The choice of core is determined by the cross-sectional area of ​​the stator S. Stamped stator plates do not fully correspond to the parameters of electrical transformer steel, therefore it is not advisable to reduce the cross-section S to less than 40 - 45 cm.

Figure 5. Scheme of fastening the terminals of the CA windings.

The stator is freed from the housing, the stator windings are removed from the internal slots, the groove bridges are cut off with a chisel, the inner surface is protected with a file or an abrasive wheel, the sharp edges of the core are rounded and wrapped tightly, covering it with cotton insulating tape. The core is ready for winding windings.

Selection of windings. For primary (network) windings, it is better to use a special copper winding wire in cold steel. (fiberglass) insulation. Wires in rubber or rubber-fabric insulation also have satisfactory heat resistance. Wires in polyvinyl chloride (PVC) insulation are unsuitable for work at elevated temperatures (and this is already included in the design of amateur SA) due to its possible melting, leakage from the windings and their short circuit. Therefore, the polyvinyl chloride insulation from the wires must either be removed and the wires wrapped along the entire length of the cotton wool. with insulating tape, or do not remove it, but wrap the wire over the insulation. Another proven winding method is also possible. But more on that below.

When selecting the cross-section of the winding wires, taking into account the specifics of the work of S.A. (periodic) we allow a current density of 5 A/mm 2. With a welding current of 130 - 160 A (electrode dе = 4 mm), the power of the secondary winding will be P 2 = Isw x 160x24 = 3.5 - 4 kW, the power of the primary winding, taking into account losses, will be about 5 - 5.5 kW, and therefore the maximum current of the primary winding can reach 25 A. Consequently, the cross-section of the wire of the primary winding S 1 must be at least 5 - 6 mm. In practice, it is advisable to use a wire with a cross section of 6 - 7 mm 2. Either it is a rectangular busbar or a copper winding wire with a diameter (without insulation) of 2.6 - 3 mm. (Calculation using the well-known formula S = piR 2, where S is the area of ​​the circle, mm 2 pi = 3.1428; R is the radius of the circle, mm.) If the cross-section of one wire is insufficient, winding in two is possible. When using aluminum wire, its cross-section must be increased by 1.6 - 1.7 times. Is it possible to reduce the cross-section of the network winding wire? Yes, you can. But at the same time S.A. will lose the required power reserve, will heat up faster, and the recommended core cross-section S = 45 - 55 cm in this case will be unreasonably large. The number of turns of the primary winding W 1 is determined from the following relationship: W 1 = [(30 - 50):S] x U 1 where 30-50 is a constant coefficient; S - core cross-section, cm 2, W 1 = 240 turns with bends from 165, 190 and 215 turns, i.e. every 25 turns.

Figure 6. Diagram of methods for winding CA windings on a rod-type core.

A larger number of network winding taps, as practice shows, is impractical. And that's why. By reducing the number of turns of the primary winding, both the power SA and Uxx increase, which leads to an increase in arc voltage and a deterioration in welding quality. Consequently, it is impossible to cover the range of welding currents without deteriorating the quality of welding by simply changing the number of turns of the primary winding. To do this, it is necessary to provide for switching the turns of the secondary (welding) winding W 2.

The secondary winding W 2 must contain 65 - 70 turns of an insulated copper bus with a cross-section of at least 25 mm (preferably a cross-section of 35 mm). A flexible stranded wire (for example, a welding wire) and a three-phase stranded power cable are also quite suitable. The main thing is that the cross-section of the power winding should not be less than required, and the insulation should be heat-resistant and reliable. If the wire cross-section is insufficient, winding in two or even three wires is possible. When using aluminum wire, its cross-section must be increased by 1.6 - 1.7 times.

Rice. 5. Fastening the terminals of the CA windings: 1 - CA housing; 2 - washers; 3 - terminal bolt; 4 - nut; 5 - copper tip with wire.

The difficulty of purchasing switches for high currents, and practice shows that it is easiest to insert the welding winding leads through copper lugs under terminal bolts with a diameter of 8 - 10 mm (Fig. 5). Copper lugs are made from copper tubes of suitable diameter 25 - 30 mm long and attached to the wires by crimping and preferably soldering. Let us especially focus on the order of winding the windings. General rules:

1. Winding should be done along an insulated core and always in the same direction (for example, clockwise).
2. Each layer of the winding is insulated with a layer of cotton wool. insulation (fiberglass, electrical cardboard, tracing paper), preferably impregnated with bakelite varnish.
3. The winding terminals are tinned, marked, and secured with cotton wool. braid, additionally put cotton on the terminals of the network winding. cambric.
4. In case of doubt about the quality of insulation, winding can be carried out using a cotton cord, as if in two wires (the author used cotton thread for fishing). After winding one layer, winding with cotton. the thread is fixed with glue, varnish, etc. and after drying, wind the next row.

Figure 7. Diagram of methods for winding CA windings on a toroidal core.

Let's consider the order of arrangement of windings on a rod-type magnetic core. The network winding can be positioned in two main ways. The first method allows you to obtain a more “hard” welding mode. The network winding in this case consists of two identical windings W 1 W 2, located on different sides of the core, connected in series and having the same wire cross-section. To adjust the output current, taps are made on each of the windings, which are closed in pairs (Fig. 6a, c).

The second method involves winding the primary (network) winding on one side of the core (Fig. 6 c, d). In this case, the SA has a steeply falling characteristic, welds “softly”, the arc length has less influence on the value of the welding current, and therefore on the quality of welding. After winding the primary winding of the CA, it is necessary to check for the presence of short-circuited turns and the correctness of the selected number of turns. The welding transformer is connected to the network through a fuse (4 - 6A) and preferably an AC ammeter. If the fuse burns out or gets very hot, then this is a clear sign of a short-circuited turn. Consequently, the primary winding will have to be rewound, paying special attention to the quality of the insulation.

Rice. 6. Methods for winding CA windings on a rod-type core: a - network winding on both sides of the core; b - the corresponding secondary (welding) winding, connected back-to-back; c - network winding on one side of the core; g - the corresponding secondary winding, connected in series.

If the welding machine makes a loud noise and the current consumption exceeds 2 - 3 A, then this means that the number of primary windings is underestimated and it is necessary to wind up a certain number of turns. A working CA consumes no-load current of no more than 1 - 1.5 A, does not heat up and does not buzz much. The secondary winding CA is always wound on both sides of the core. For the first winding method, the secondary winding also consists of two identical halves, connected to increase the stability of arc burning (Fig. 6) in counter-parallel, and the wire cross-section can be taken slightly smaller - 15 - 20 mm 2.

Figure 8. Connection diagram for measuring instruments.

For the second winding method, the main welding winding W 2 1 is wound on the side of the core free from windings and makes up 60 - 65% of the total number of turns of the secondary winding. It serves mainly to ignite the arc, and during welding, due to a sharp increase in the magnetic dissipation flux, the voltage on it drops by 80 - 90%. An additional welding winding W 2 2 is wound on top of the primary one. Being a power supply, it maintains the welding voltage and, consequently, the welding current within the required limits. The voltage across it drops in welding mode by 20 - 25% relative to the no-load voltage. After manufacturing the SA, it is necessary to set it up and check the quality of welding with electrodes of different diameters. The setup process is as follows. To measure welding current and voltage, you need to purchase two electrical measuring instruments - an AC ammeter for 180-200 A and an AC voltmeter for 70-80 V.

Rice. 7. Methods for winding CA windings on a toroidal core: 1.2 - uniform and sectional winding of windings, respectively: a - network b - power.

Their connection diagram is shown in Fig. 8. When welding with different electrodes, take the values ​​of the welding current - Iw and welding voltage Uw, which must be within the required limits. If the welding current is small, which happens most often (the electrode sticks, the arc is unstable), then in this case, either by switching the primary and secondary windings, the required values ​​are set, or the number of turns of the secondary winding is redistributed (without increasing them) towards increasing the number of turns wound on top network winding. After welding, you can make a break or saw the edges of the welded products, and the quality of the weld will immediately become clear: the depth of penetration and the thickness of the deposited layer of metal. It is useful to create a table based on the measurement results.

Figure 9. Diagram of welding voltage and current meters and design of a current transformer.

Based on the data in the table, optimal welding modes are selected for electrodes of different diameters, remembering that when welding with electrodes, for example, with a diameter of 3 mm, electrodes with a diameter of 2 mm can be cut, because The cutting current is 30-25% higher than the welding current. The difficulty of purchasing the measuring instruments recommended above forced the author to resort to making a measuring circuit (Fig. 9) based on the most common 1-10 mA DC milliammeter. It consists of voltage and current meters assembled using a bridge circuit.

Rice. 9. Schematic diagram of welding voltage and current meters and design of a current transformer.

The voltage meter is connected to the output (welding) winding SA. The setting is carried out using any tester that controls the welding output voltage. Using a variable resistance R.3, the arrow of the device is set to the final scale division at the maximum value of Uxx. The voltage meter scale is quite linear. For greater accuracy, you can remove two or three control points and calibrate the measuring device to measure voltages.

Setting up a current meter is more difficult because it is connected to a homemade current transformer. The latter is a toroidal core with two windings. The dimensions of the core (external diameter 35-40 mm) are not of fundamental importance, the main thing is that the windings fit. Core material - transformer steel, permalloy or ferrite. The secondary winding consists of 600 - 700 turns of insulated copper wire of the PEL, PEV brand, preferably PELSHO, with a diameter of 0.2 - 0.25 mm and is connected to a current meter. The primary winding is a power wire running inside the ring and connected to the terminal bolt (Fig. 9). Setting up the current meter is as follows. To the power (welding) winding S.A. connect a calibrated resistance made of thick nichrome wire for 1 - 2 seconds (it gets very hot) and measure the voltage at the SA output. The current flowing in the welding winding is determined. For example, when connecting Rн = 0.2 ohm Uout = 30V.

Mark a point on the instrument scale. Three to four measurements with different RH are enough to calibrate the current meter. After calibration, the instruments are installed on the CA body, using generally accepted recommendations. When welding under different conditions (high or low current network, long or short supply cable, its cross-section, etc.), the SA is adjusted by switching the windings. to the optimal welding mode, and then the switch can be set to the neutral position. A few words about resistance spot welding. Towards the design of S.A. This type has a number of specific requirements:

1. The power delivered at the time of welding should be maximum, but not more than 5-5.5 kW. In this case, the current consumed from the network will not exceed 25 A.
2. The welding mode must be “hard”, and therefore, the winding of the windings S.A. should be carried out according to the first option.
3. The currents flowing in the welding winding reach values ​​of 1500-2000 A and higher. Therefore, the welding voltage should be no more than 2-2.5V, and the no-load voltage should be 6-10V.
4. The cross-section of the primary winding wires is at least 6-7 mm, and the cross-section of the secondary winding is at least 200 mm. This cross-section of wires is achieved by winding 4-6 windings and then connecting them in parallel.
5. It is not practical to make additional taps from the primary and secondary windings.
6. The number of turns of the primary winding can be taken as the minimum calculated due to the short duration of the operation of the SA.
7. It is not recommended to take a cross-section of the core (core) less than 45-50 cm.
8. Welding tips and underwater cables to them must be copper and pass appropriate currents (tip diameter 12-14 mm).

A special class of amateur S.A. represent devices manufactured on the basis of industrial lighting and other transformers (2-3 phase) with an output voltage of 36V and a power of at least 2.5-3 kW. But before undertaking the alteration, it is necessary to measure the cross-section of the core, which should be at least 25 cm, and the diameters of the primary and secondary windings. It will immediately become clear to you what you can expect from remaking this transformer.

And finally, some technological tips.

The welding machine must be connected to the network using a wire with a cross-section of 6-7 mm through an automatic machine with a current of 25-50 A, for example AP-50. The diameter of the electrode, depending on the thickness of the metal being welded, can be selected based on the following relationship: da= (1-1.5)L, where L is the thickness of the metal being welded, mm.

The arc length is selected depending on the diameter of the electrode and is on average 0.5-1.1 d3. It is recommended to weld with a short arc of 2-3 mm, the voltage of which is 18-24 V. Increasing the length of the arc leads to a violation of the stability of its combustion, increased losses due to waste and spatter, and a decrease in the depth of penetration of the base metal. The longer the arc, the higher the welding voltage. The welding speed is selected by the welder depending on the grade and thickness of the metal.

When welding with straight polarity, the plus (anode) is connected to the part and the minus (cathode) to the electrode. If it is necessary for less heat to be generated on the parts, for example, when welding thin-sheet structures, reverse polarity welding is used (Fig. 1). In this case, the minus (cathode) is connected to the part being welded, and the plus (anode) is connected to the electrode. This not only ensures less heating of the part being welded, but also accelerates the process of melting the electrode metal due to the higher temperature of the anode zone and greater heat input.

Welding wires are connected to the SA through copper lugs under the terminal bolts on the outside of the welding machine body. Poor contact connections reduce the power characteristics of the SA, deteriorate the quality of welding and can cause overheating and even fire of the wires. If the welding wires are short (4-6 m), their cross-section should be at least 25 mm. When performing welding work, it is necessary to comply with fire and electrical safety rules when working with electrical appliances.

Welding work should be carried out in a special mask with protective glass grade C5 (for currents up to 150-160 A) and gloves. Perform all switching of the SA only after disconnecting the welding machine from the network.

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, and cheap ones are of poor quality. To implement the idea of ​​making your own welder, you need to acquire special equipment that will allow you to hone the quality skills of a specialist in real conditions.

Types and characteristics of the tool

After all the necessary conditions of the preparatory stage have been 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 devices are capable of ensuring the standard quality of seams in 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. Using a larger cross-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.

A VRP cable or a ShRPS wire, which will be used to connect to the network, is connected to the primary winding of the finished welding transformer. 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 welding jobs, 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 a significant drawback. It must be used with additional precautions. Without galvanic isolation from the 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.

You can use pencil leads as electrodes for a DIY mini welding machine. 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.

In the arsenal of a home craftsman there are many tools for all occasions.

A welding machine is an indispensable device for real craftsmen. It can be bought in stores. However, it is much more interesting and cheaper to assemble it yourself.

Some also have a welding machine, which every craftsman dreams of.

Today it can be purchased in specialized stores. There are many models. Various device accessories and consumables are sold. Is it possible to make a welding machine with your own hands? The answer is simple: it is possible and even necessary!

Types of Welding Machines

All welding machines are divided into gas and electric. Gas installations are not entirely suitable for domestic use. They require special treatment, as they are equipped with explosive gas cylinders. Therefore, we should talk only about electrical devices. They are also different:

The welding equipment is economical and ideal for home use.

1. Generators. These installations have their own current generator. They are very heavy and bulky in size. Not suitable for home assembly and use.
2. Transformers. Such devices can be powered from a 220 or 380 volt network. They are very popular, especially semi-automatic ones.
3. Inverters. Very economical devices, ideal for the home. They are lightweight, but have a rather complex electronic circuit.
4. Rectifiers. Easy to make and use. Even novice welders can make quality welds. Ideal for DIY assembly.

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Where to start assembling an inverter apparatus?

To assemble the inverter, you need to select a circuit that will provide the necessary operating parameters of the device. It is recommended to use Soviet-made parts. This is especially true for diodes, capacitors, transistors, resistors, chokes, thyristors and finished transformers. The equipment assembled on these parts does not require complex adjustments. All parts are very compactly located on the board. To make the device yourself, you can select the following parameters:

1. The welding machine must work with electrodes with a diameter of up to 4-5 mm.
2. The operating current is no more than 250 A.
3. Power source - household network voltage 220 V.
4. Adjustable welding current within 30-220 A.

The welding machine consists of several blocks: power supply, rectifier and inverter.
You can start making an inverter-type welding machine with your own hands by winding a transformer in this order:

To assemble the inventory, you will need a ferrite core.

1. You need to take a ferrite core Ш8х8. You can use W7x7.
2. Primary winding No. 1 consists of 100 turns, wound with PEV 0.3 wire.
3. The secondary winding No. 2 is wound with a wire with a cross-section of 1 mm. The number of turns is 15.
4. Winding No. 3 - 15 turns of PEV wire 0.2 mm.
5. Windings No. 4 and No. 5 consist of 20 turns of wire with a cross section of 0.35 mm.
6. To cool the transformer, you can use a 220 V, 0.13 A fan. These parameters correspond to a fan from a Pentium 4 computer.

In order for transistor switches to operate smoothly, they need to be supplied with voltage after the rectifier and smoothing capacitors. The rectifier unit is assembled according to a simple circuit board. All components of the welding machine are fixed in the housing. It’s good if the craftsman has a suitable housing for a radio device, then he won’t have to make it from scrap materials.

An LED indicator is placed on the front side of the case, which by its glow notifies that the device is connected to the network. You can also install an additional switch of any type and a protective fuse. The fuse can be installed on the rear wall, as well as in the housing itself. It depends on its design and dimensions. A variable resistance, with the help of which the operating current will be adjusted, is also located on the front side of the housing.

If the electrical circuits are assembled correctly, everything is checked using a tester or other device, you can test the device.

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How to assemble a transformer apparatus?

The process of assembling a transformer welding machine is somewhat different from the previous version. It runs on alternating current. For DC welding, a simple attachment is assembled for it. To assemble the device with your own hands, you need to get transformer iron for the core and several tens of meters of thick copper busbar or just thick wire. You can look for these things at collection points for non-ferrous and ferrous metals, from friends and acquaintances. It is recommended to make the core U-shaped, but it can also be round or toroidal. Some craftsmen successfully use the stator of a burnt-out electric motor as a core. For a U-shaped core, the assembly order can be as follows:

To make the primary winding you will need a winding wire.

1. Assemble the core from transformer iron to its optimal cross-section of about 55 square centimeters. More is possible, but the device will be heavy. With a cross section of less than 30 cm², the device may lose some of its qualities.
2. To make the primary winding, a special winding wire with a cross section of 5-7 mm² is ideal. It is made of copper and has heat-resistant fiberglass or cotton insulation. This is very important, since during operation the winding can heat up to temperatures above 100 degrees. The wire cross-section is usually square or rectangular. It is not always possible to find such a wire. You can replace it with a regular wire of the same cross-section and modify it: remove the insulation, wrap the wire with strips of fiberglass, thoroughly soak it with special electrical varnish and dry it. The primary winding consists of 200-230 turns.
3. For the secondary winding, you can first wind 50-60 turns. There is no need to cut the wire. It is necessary to turn on the primary winding in the network. Find a place on the secondary winding wires where the voltage will be 60-65 V. In order to find this point, you have to unwind or wind additional turns. You can wind aluminum wire, increasing the cross-section by 1.7 times.
4. The simplest transformer has been assembled. All that remains is to place it in a suitable housing.
5. For the terminals of the secondary winding, copper terminals are made. Take a tube with a diameter of about 10 mm and a length of 3-4 cm. Its end is riveted and a hole is drilled in it, the diameter of which is 10 mm. At the other end of the tube, you need to insert the end of the wire, stripped of insulation, and compress it with light blows of the same hammer. To strengthen the contact of the wire with the terminal tube, you can apply notches to it with a core. Homemade terminals are screwed to the body with M10 bolts and nuts. It is advisable to select copper parts. When winding the secondary winding, you can make taps every 5-10 turns of wire. These taps will allow you to stepwise change the voltage on the electrode.
6. All that remains is to make the electrode holder. It can be made from a pipe with a diameter of about 18-20 mm. Its total length is approximately 25 cm. At the ends, 3-4 cm from the end, notches are cut to approximately half the diameter. The electrode is inserted into the recess and pressed by a spring made from a welded piece of steel wire with a diameter of 6 mm. The same wire from which the secondary winding is made is attached to the other end with a screw and an M8 nut. A rubber tube of suitable internal diameter is placed on the holder. It is recommended to connect the device to your home network using a switch and wires with a cross-section of 1.5 mm² or larger. The current in the primary winding usually does not exceed 25 A. In the secondary winding it can be from 60 to 120 A. During operation, it is recommended to take a break after 10-15 electrodes with a diameter of 3 mm so that the transformer cools down. With thinner electrodes this may not be necessary. In cutting mode, breaks should be taken more often.

Nowadays, it is difficult to imagine any work with metal without the use of a welding machine. Using this device, you can easily connect or cut iron of various thicknesses and dimensions. Naturally, to perform high-quality work you will need certain skills in this matter, but first of all you need the welder itself. Nowadays, of course, you can buy it, as well as, in principle, hire a welder, but in this article we will talk about how to make a welding machine with your own hands. Moreover, with all the wealth of different models, reliable ones are quite expensive, and cheap ones do not shine with quality and durability. But even if you decide to buy a welder in a store, reading this article will help you choose the necessary device, since you will know the basics of their circuitry. There are several types of welders: direct current, alternating current, three-phase and inverter. In order to determine which option you need, we will consider the design and device of the first two types, which you can assemble with your own hands at home without any specific skills.

AC

This type of welding machine is one of the most common options, both in industry and in private households. It is easy to use and, compared to others, can be made quite easily at home, as evidenced by the photo below. To do this, you need to have a wire for the primary and secondary windings, as well as a transformer steel core for winding the welder. In simple words, an AC welding machine is a high-power step-down transformer.

The optimal voltage when operating a welding machine assembled at home is 60V. The optimal current is 120-160A. Now it’s easy to calculate what cross-section the wire should have in order to make the primary winding of the transformer (the one that will be connected to the 220 V network). The minimum cross-sectional area of ​​the copper wire should be 3-4 square meters. mm, the optimal is 7 sq. mm, because it is necessary to take into account the possible additional load, as well as the necessary margin of safety. We find that the optimal diameter of the copper core for the primary winding of a step-down transformer should be 3 mm. If you decide to take an aluminum wire to make a welding machine with your own hands, then the cross-section for the copper wire must be multiplied by a factor of 1.6.

It is important that the wires are covered in rag braiding; you cannot use conductors in PVC insulation - when the wires heat up, it will melt and this will happen. If you do not have a wire of the required diameter, you can use thinner wires, winding them in parallel. But then it should be taken into account that the thickness of the winding will increase, and, accordingly, the dimensions of the device itself. It must be borne in mind that the limiting factor may be a free window in the core and the wire may simply not fit there. For the secondary winding, you can use a thick stranded copper wire - the same as the core on the holder. Its cross-section should be selected based on the current in the secondary winding (remember that we are focusing on 120 - 160A) and the length of the wires.

The first step is to make a transformer core for a homemade welding machine. The best option would be a rod-type core as shown in Figure 1:

This core must be made from transformer steel plates. The thickness of the plates should be from 0.35 mm to 0.55 mm. This is necessary to reduce . Before assembling the core, you need to calculate its dimensions, this is done as follows:

• First, the window size is calculated. Those. Dimensions c and d in Figure 1 must be chosen such as to accommodate all the windings of the transformer.
• Secondly, the roll area, which is calculated by the formula: Roll = a*b, must be at least 35 square meters. cm. If there is more Skren, then the transformer will heat up less and, accordingly, work longer, and you will not need to interrupt often in order for it to cool down. It is better that the Skrena is equal to 50 square meters. cm.

Next, we proceed to assembling the plates of a homemade welding machine. It is necessary to take the L-shaped plates and fold them, as shown in Figure 2, until you can make a core of the required thickness. Then we fasten it with bolts at the corners. Finally, it is necessary to process the surface of the plates with a file and insulate them by wrapping them with rag insulation in order to further protect the transformer from breakdown to the housing.

Next, we proceed to winding the welding machine from the step-down transformer. First, we wind the primary winding, which will consist of 215 turns, as shown in Figure 3.

It is advisable to make a branch from 165 and 190 turns. We attach a thick textolite plate to the top of the transformer. We fix the ends of the windings on it using a bolted connection, noting that the first bolt is a common wire, the second is a branch from the 165th turn, the 3rd is a branch from the 190th turn and the 4th is from the 215th. This will make it possible to subsequently regulate the current during welding by switching between different terminals of your welding device. This is a very important function, and the more branches you make, the more precise your adjustment will be.

Then we proceed to winding 70 turns of the secondary winding, as shown in Figure 4.

A smaller number of turns are wound on the other side of the core - where the primary winding is wound. The ratio of turns should be approximately 60% to 40%. This ensures that after you catch the arc and start welding, the eddy currents will partially turn off the operation of the winding with a large number of turns, which will lead to a decrease in the welding current, and accordingly improve the quality of the seam. This way the arc will be easy to catch, but too much current will not interfere with quality welding. We will also secure the ends of the winding with bolts to the textolite plate. You can not attach them, but run the wires directly to the electrode holder and the crocodile to ground; this will remove connections where there could potentially be a voltage drop and heating. For better cooling, it is highly advisable to install a fan for blowing, for example from a refrigerator or microwave.

Now your homemade welding machine is ready. Having connected the holder and ground to the secondary winding, it is necessary to connect the network to the common wire and the wire extending from the 215th turn of the primary winding. If you need to increase the current, you can make fewer turns of the primary winding by switching the second wire to a contact with fewer turns. The current can be reduced using a resistance made from a piece of transformer steel bent into a spring and connected to a holder. It is always necessary to ensure that the welding machine does not overheat; to do this, regularly check the temperature of the core and windings. For these purposes, you can even install an electronic thermometer.

This is how you can make a welding machine from a step-down transformer with your own hands. As you can see, the instructions are not too complicated and even an inexperienced electrician can assemble the device on their own.

DC

Some types of welding require a DC welder. This tool can be used to weld cast iron and stainless steel. You can make a DC welding machine with your own hands in no more than 15 minutes by remaking a homemade product using alternating current. To do this, you need to connect a rectifier assembled with diodes to the secondary winding. As for the diodes, they must withstand a current of 200 A and have good cooling. D161 diodes are suitable for this.

Capacitors C1 and C2 with the following characteristics will help us equalize the current: capacitance 15000 μF and voltage 50V. Next, we assemble the circuit shown in the drawing below. Inductor L1 is needed to regulate the current. Contacts x4 are plus for connecting the holder, and x5 are minus for supplying current to the part to be welded.

Three-phase welding machines are used for welding in industrial conditions, they are equipped with two-electrode holders, so we will not consider them in this article, and inverters are made on the basis of printed circuit boards and complex circuits with a large number of expensive radio components and a complex setup process using special equipment. However, we still recommend that you familiarize yourself with the inverter design in the video below.

Visual master classes

So, if you decide to make a welding machine at home, we recommend watching the video lessons provided below, which will clearly show how to assemble a simple welder yourself from scrap materials, and will also explain to you some of the details and nuances of the work:

Now you know the basic principles of the design of welders and you can make a welding machine with your own hands, both on direct and alternating current, using the instructions from our article.

Also read:

A good welding machine makes all metal work much easier. It allows you to connect and cut various iron parts, which differ in their thickness and steel density.

Modern technologies offer a huge selection of models that differ in power and size. Reliable designs have a fairly high cost. Budget options usually have a short service life.

Our material provides detailed instructions on how to make a welding machine with your own hands. Before starting the work process, it is recommended to familiarize yourself with the type of welding equipment.

Types of welding machine

The devices of this technology come in several types. Each mechanism has some features that are reflected in the work performed.

Modern welding machines are divided into:

• DC models;
• with alternating current
• three-phase
• vector

The AC model is considered the simplest mechanism that you can easily make yourself.

A simple welding machine allows you to perform complex work with iron and thin steel. To assemble such a structure, you must have a certain set of materials.

These include:

• wire for winding;
• core made of transformer steel. It is necessary for winding the welder.

All these parts can be purchased in specialized stores. Detailed consultation with specialists helps you make the right choice.

AC design

Experienced welders call this design a step-down transformer.

How to make a welding machine with your own hands?

The first thing you need to do is to correctly manufacture the main core. For this model, it is recommended to choose a rod type of part.

To make it you will need plates made of transformer steel. Their thickness is 0.56 mm. Before you begin assembling the core, you must observe its dimensions.

How to correctly calculate the parameters of a part?

Everything is quite simple. The dimensions of the central hole (window) must accommodate the entire winding of the transformer. The photo of the welding machine shows a detailed diagram of the assembly of the mechanism.

The next step is to assemble the core. To do this, take thin transformer plates, which are connected to each other to the required thickness of the part.

Next, we wind a step-down transformer consisting of turns of thin wire. To do this, make 210 turns of thin wire. On the other side, a winding of 160 turns is made. The third and fourth primary windings should contain 190 turns. After this, a thick platinum is attached to the surface.

The ends of the wound wire are secured with a bolt. I mark its surface with the number 1. The following ends of the wire are secured in a similar way with the corresponding markings applied.

Note!

The finished structure should contain 4 bolts with different numbers of turns.

In the finished design, the winding ratio will be 60% to 40%. This result ensures normal operation of the device and good quality of welding fastening.

You can control the supply of electrical energy by switching wires to the required amount of winding. It is not recommended to overheat the welding mechanism during operation.

DC apparatus

These models allow you to perform complex work on thick steel sheets and cast iron. The main advantage of this mechanism is its simple assembly, which does not take much time.

The welding invector is a secondary winding design with an additional rectifier.

Note!

It will be made of diodes. In turn, they must withstand an electric current of 210 A. For this, elements marked D 160-162 are suitable. Such models are quite often used for work on an industrial scale.

The main welding injector is made from a printed circuit board. This semi-automatic welding machine can withstand power surges during long-term operation.

Repairing a welding machine is not difficult. Here it is enough to replace the damaged area of ​​the mechanism. In the event of a serious breakdown, it is necessary to re-install the primary and secondary windings.

Photo of a do-it-yourself welding machine

Note!

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