Homemade machine for spot welding from latra. Homemade welding machines and devices. What are we going to talk about?

The homemade welding machine from LATR 2 built on the basis of a nine-amp LATR 2 (laboratory adjustable autotransformer) and its design provides for adjustment welding current. The presence of a diode bridge in the design of the welding machine allows welding with direct current.

Current regulator circuit for a welding machine

The operating mode of the welding machine is regulated by variable resistor R5. Thyristors VS1 and VS2 each open in their own half-cycle alternately for a certain period of time thanks to a phase-shifting circuit built on elements R5, C1 and C2.

As a result, it becomes possible to change the input voltage on the primary winding of the transformer from 20 to 215 volts. As a result of the transformation, a reduced voltage appears on the secondary winding, allowing you to easily ignite the welding arc at terminals X1 and X2 when welding with alternating current and at terminals X3 and X4 when welding with direct current.

The welding machine is connected to the electrical network using an ordinary plug. A paired 25A circuit breaker can be used as switch SA1.

Material: ABS + metal + acrylic lenses. LED lights...

Conversion of LATR 2 into a homemade welding machine

First, remove from the autotransformer protective cover, electrical removable contact and fastening. Next, good electrical insulation is wound onto the existing 250 volt winding, for example, fiberglass, on top of which 70 turns of the secondary winding are laid. For the secondary winding, it is advisable to choose a copper wire with a cross-sectional area of ​​about 20 square meters. mm.

If there is no wire of a suitable cross-section, you can wind it from several wires with a total cross-sectional area of ​​20 sq. mm. The modified LATR2 is mounted in a suitable homemade housing with ventilation holes. There you also need to install a regulator board, a packet switch, as well as terminals for X1, X2 and X3, X4.

In the absence of LATR 2, the transformer can be made homemade by winding the primary and secondary windings on a transformer steel core. The core cross-section should be approximately 50 square meters. cm. The primary winding is wound with PEV2 wire with a diameter of 1.5 mm and contains 250 turns, the secondary winding is the same as that wound on LATR 2.

At the output of the secondary winding, a diode bridge consisting of powerful rectifier diodes is connected. Instead of the diodes indicated in the diagram, you can use D122-32-1 diodes or 4 VL200 diodes (electric locomotive). Diodes for cooling must be installed on homemade radiators with an area of ​​at least 30 square meters. cm.

Another important point is the choice of cable for the welding machine. For this welder, it is necessary to use a copper stranded cable in rubber insulation with a cross-section of at least 20 sq. mm. You need two pieces of cable 2 meters long. Each must be tightly crimped with terminal lugs to connect to the welding machine.

When constructing or repairing equipment or household appliances, quite often there is a need to weld some elements. To connect the parts, you will need to use a welding machine. Today you can easily purchase a similar design, but you should know that you can also make homemade welding machines.

Welding machines come in permanent and alternating current. The latter are used to weld metal workpieces of small thickness at low currents. The DC welding arc is more stable, and it is possible to weld with direct and reverse polarity. IN in this case can be used electrode wire without coating or electrodes. To make the arc more stable, it is recommended to increase the voltage at low currents idle move welding windings.

To rectify alternating current, you should use ordinary bridge rectifiers on large semiconductors with cooling radiators. In order to smooth out voltage ripples, one of the terminals must be connected to the electrode holder through a special choke, which is a coil of several dozen turns of a copper busbar with a cross-section of 35 mm. Such a bus can be wound on any core; it is best to use a core from a magnetic starter.

To straighten and smoothly regulate the welding current, you should use more complex circuits using large thyristors for control.

The advantages of constant current regulators include their versatility. They have a wide range of voltage configurations, and therefore such elements can be used not only for gradually adjusting the current, but also for charging batteries, power supply electrical elements for heating and other circuits.

AC welding machines can be used to connect workpieces with electrodes whose diameter is more than 1.6 mm. The thickness of the joined workpieces can be more than 1.5 mm. In this case, there is a high welding current, and the arc burns stably. Electrodes that are made for welding exclusively with alternating current can be used.

A stable arc can be obtained if the welding fixture has a falling external characteristic, which determines the relationship between the current and voltage in the welding chain.

What should be considered in the manufacturing process of welding machines?

To stepwise cover the spectrum of welding currents, switching of both primary and secondary windings is necessary. For a smooth current configuration within the selected spectrum, you should use mechanical properties movement of the windings. If you remove the welding winding in relation to the network winding, the magnetic leakage fluxes will increase. Please be aware that this may result in a reduction in welding current. In production homemade design for welding there is no need to strive to completely cover the spectrum of welding currents. It is recommended that you first assemble it to work with 2-4 mm electrodes. If you need to work with small welding currents in the future, the design can be supplemented with a separate device for straightening with gradual adjustment of the welding current.

Self-made structures must satisfy certain requirements, the main ones being the following:

1. Relatively compact and light weight. Such parameters can be reduced by reducing the power of the structure.
2. Sufficient operating time from a 220 V power supply. It can be increased by using steel with high magnetic permeability and heat-resistant insulation of wires for winding.

Such requirements can be easily met if you know the basics of constructing welding structures and adhere to the technology for their manufacture.

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How to choose the type of core for the structure being manufactured?

In the process of manufacturing such structures, rod magnetic wires are used; they are more technologically advanced. The core is made from electrical steel plates of any configuration, the thickness of the material should be 0.35-0.55 mm. The elements will need to be tightened with studs that are covered with insulating material.

When choosing a core, you should take into account the size of the “window”. The structure must accommodate the windings of the elements. It is not recommended to use cores with cross section 25-35 mm, since in this case the manufactured structure will not have the necessary power supply, as a result of which high-quality welding will be quite difficult to produce. In this case, overheating of the device also cannot be ruled out. The core should have a cross-section of 45-55 mm.

In some cases, they are produced welding structures with toroidal cores. These devices have higher electrical performance and low electrical losses. Making such devices is much more difficult, since the windings will need to be placed on the torus. You should know that winding in this case is quite difficult.

The cores are made of transformer strip iron, which is rolled into a torus-shaped roll.

To increase the internal diameter of the torus, with inside you need to unwind part of the metal tape, and then wind it on outer side core.

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How to choose the right winding structure?

For the primary winding, it is recommended to use copper wire, which is covered with fiberglass insulating material. You can also use wires that are covered with rubber. It is not allowed to use cords that are covered with polyvinyl chloride insulation.

It is not recommended to make a large number of taps of the network winding. By reducing the number of turns of the primary winding, the power of the welding machine will increase. This will lead to an increase in arc voltage and deterioration in the quality of the workpiece connection. By changing the number of turns of the primary winding, it will not be possible to overlap the spectrum of welding currents without deteriorating the welding properties. To do this, it will be necessary to provide for switching the turns of the secondary welding winding.

The secondary winding should contain 67-70 turns of a copper busbar with a cross-section of 35 mm. Stranded can be used network cable or flexible stranded cord. Insulation material must be heat-resistant and reliable.

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Homemade welding machine from an autotransformer

The welding device operates from a 220 V power supply. The design has excellent electrical performance. Thanks to the use new form magnetic wire, the weight of the device is about 9 kg with dimensions of 150x125 mm. This is achieved by using strip iron, which is rolled into a torus-shaped roll. In most cases, a standard package of W-shaped plates is used. The electrical performance of a transformer design on a magnetic wire is approximately 5 times higher than that of similar plates. Electrical losses will be minimal.

Elements that will be needed to make a welding machine with your own hands:

• magnetic wire;
• autotransformer;
• electrical cardboard or varnish fabric;
• wires;
• wooden slats;
• insulating material;
• transformer;
• cable;
• casing;
• switch.

When designing, assembling or repairing something, you often have to connect parts. The types and methods of connections are different. For example, when connecting metal products, a threaded connection (screw or bolt with a nut), riveting, gluing, soldering and welding are used.

And if for the first three you only need mechanical tools, then soldering irons are needed for soldering, and for welding some craftsmen make homemade DC and AC welding machines. Many of these units have been operating without failures for decades.

Homemade AC devices

When assembling, repairing or designing household appliances or any equipment, it becomes necessary to weld several parts together. AC welding machines are expensive and not easy to buy. But it is perfectly acceptable to make them yourself. The circuits of such devices are very different.

One of original designs made on the basis of the LATR transformer (laboratory autotransformer). This device operates from a regular network using alternating current. Its electrical characteristics are very high due to the special design of the magnetic circuit.

It is made of transformer strip iron (rolled) and has the shape of a ring or torus, although a conventional AC welding machine is assembled from plates similar to the letter “W”. The characteristics of a toroidal product are 4.7 times higher, and losses are almost minimal compared to an W-shaped core.

But such transformer strip iron is now in short supply, so it is easier to get a ready-made 9-amp laboratory autotransformer (LATR) or toroidal magnetic core from a burnt product. It needs to be rewound - remove the old or burnt secondary winding and wind a new one with a thicker wire. Using all this, you will assemble a 75-155 Amp AC unit in about 1-2 hours.

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Rewind LATR

To replace the windings proceed as follows:

1. Remove the casing (if there is one).
2. Reinforcement made of non-magnetic material (plastic, aluminum) is removed along with the mechanical part.
3. Get rid of old or burnt windings:

• if the windings are not damaged, then the secondary is simply wound onto a special shuttle for use in other developments and designs. A shuttle measuring 4-5x10-20 cm can be cut from plywood;
• if the windings are burned out, then the wire is removed by any method: cut off, torn off.

1. The core is electrically insulated from the future winding by wrapping the iron in two layers of varnished cloth or making overlays from special electrical cardboard.
2. New windings are wound, isolating them from each other;
3. Assembly is carried out.

Devices made on the basis of the LATR transformer are wound with only two windings.

If the transformer burns out completely, you have to wind both windings.

The primary is performed with a 1.2 mm wire of the PEV-2 type. The approximate length of this piece is 170 m. A shuttle is used for winding. The wire is wound completely around it.

And then, having secured the end, they begin to perform translational movements with their hand inside the toroid, wrapping the insulated core with wire. Winding is done turn to turn. After winding, the primary winding is covered with insulation (the same varnished fabric).

For more reliable insulation and efficient cooling of the device, you can use the air gap method between the windings. In this case, the primary winding does not need to be insulated from above - its own coating will suffice.

The method is:

• two rings are made of thick (3-5 mm) PCB with an external gauge 3-5 mm (on each side) larger than the diameter of the core with a wound “primary”;
• the edges are chamfered (they are rounded) to avoid damage to the insulation;
• the rings are secured at the top and bottom of the core with double-sided tape;
• the secondary winding is wound.

The secondary one - 45 turns - is performed with several wires twisted together, or a busbar, which must be in glassy or CB insulation. The cross section is calculated depending on the required welding current and is 5-7 A per 1 sq. mm. For a current of 170 A you will need a busbar or twist with a cross section of 35 mm or larger. The secondary winding (for cooling) is distributed over the toroid with a gap, trying to distribute it evenly.

If you have a working autotransformer or have purchased a new one, then the work comes down to only rewinding one (secondary) winding, since the primary is already wound with wire of the required cross-section and length.

It moves in the following sequence:

• First, unscrew the metal or plastic casing (if there is one);
• remove the slider with the graphite current collector;
• remove reinforcement from non-magnetic material (plastic, aluminum);
• identify (call the tester) and mark all network outputs;
• the remaining wires are wrapped with insulation or PVC tubes are put on them and laid on the side of the LATR perpendicular to the windings;
• then the secondary winding is mounted; the turns, diameter and brand of copper wires are similar to the option described above (completely burnt).

Welding machines, or rather their transformers, are recommended to be installed by two people. The first person pulls the wire and lays it down, trying not to spoil the insulation and maintain a distance between the turns. The second holds the end of the wire, preventing it from twisting.

If the insulation is broken and the ends of at least one turn touch, an interturn short circuit will occur, the transformer will overheat and the device will fail.

Welding machines with such a transformer operate at currents of 55-180 A.

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Wiring diagram

Any design that operates from the network has its own circuit. The welding machine described above also has it.

The rewound transformer is covered with an old casing (if it fits), a new one is prepared or dispensed with without a fence. It's not that dangerous. After all, the device has an output potential of no more than 50 V. And it is much easier to cool a transformer without a casing.

The terminals of the transformer windings are connected to your device as follows:

1. Primary (I) - connected to 220 V with a 2-4 mm flexible copper wire (VRP or ShRPS). An automatic switch (Q1) is required - an automatic switch like those found in houses.
2. Carefully insulated, but also flexible PRG wires of the appropriate cross-section are attached to the secondary (multi-ampere) one.

One end is attached to the workpiece and grounded (for electrical safety). On the other, a ballast resistor is mounted (to regulate the output current) and a homemade or standard electrode holder for the device.

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Current regulators

The regulator is a 3 mm caliber coiled wire made of constantan or nichrome wire approximately 5 m long. This is a kind of ballast connected in series to the electrical holder circuit.

The spiral is fixed separately on a sheet of asbestos cement. The welding current of the machine can be changed in three ways:

1. Selection method. A large alligator clip is attached to the regulating end. The current is changed by moving the clamp in a spiral. If you strengthen the spiral only at the ends (or straighten), the adjustment will be smooth.
2. Switching method. Take the switch. Its common terminal is connected to the control wire. The remaining terminals are connected to spiral turns. The current is controlled by discrete movement of the slider.
3. Replacement method. The current is changed by selecting electrodes (thick and thin, long and short). Regulation occurs within small limits. This method is almost never used.

These machines change the welding current by adjusting the secondary winding. A large current is removed from it, so changing the current electronically is unprofitable. It is necessary to install powerful parts, huge radiators and appropriate cooling.

No craftsman or homely owner will refuse a compact and at the same time quite reliable, cheap and easy-to-manufacture “welder”. Especially if he finds out that this device is based on an easily upgradeable 9-ampere (familiar to almost everyone with school lessons physics) laboratory autotransformer LATR2 and a homemade thyristor mini-regulator with a rectifier bridge. They allow you not only to safely connect to a household AC lighting network with a voltage of 220V, but also to change Usv on the electrode, and therefore select the desired value of welding current. Operating modes are set using a potentiometer. Together with capacitors C2 and C3, it forms phase-shifting chains, each of which, when triggered during its half-cycle, opens the corresponding thyristor for a certain period of time. As a result, an adjustable 20-215 V appears on the primary winding of the welding T1. Transforming in the secondary winding, the required -Usv make it easy to ignite the arc for welding on alternating (terminals X2, X3) or rectified (X4, X5) current. Fig.1.

Homemade welding machine based on LATR. Welding transformer based on the widely used LATR2 (a), its connection to the main circuit electrical diagram a homemade adjustable machine for welding on alternating or direct current (b) and a voltage diagram explaining the operation of a transistor regulator of the electric arc combustion mode. Resistors R2 and R3 bypass the control circuits of thyristors VS1 and VS2. Capacitors C1, C2 are reduced to permissible level radio interference accompanying an arc discharge. A neon light bulb with a current-limiting resistor R1 is used as a light indicator HL1, signaling that the device is connected to the household power supply.

To connect the “welder” to the apartment electrical wiring, the usual plug X1. But it is better to use a more powerful electrical connector, which is commonly called a “Euro plug-Euro socket”. And as a switch SB1, a “packet” VP25, designed for a current of 25 A and allowing you to open both wires at once, is suitable. As practice shows, it makes no sense to install any kind of fuses (anti-overload circuit breakers) on the welding machine. Here you have to deal with such currents, if exceeded, the protection at the network input to the apartment will definitely work. To manufacture the secondary winding, the casing-guard, current-collecting slider and mounting hardware are removed from the base LATR2. Then, reliable insulation (for example, made of varnished fabric) is applied to the existing 250 V winding (the 127 and 220 V taps remain unclaimed), on top of which a secondary (step-down) winding is placed. And this is 70 turns of an insulated copper or aluminum busbar with a diameter of 25 mm2. It is acceptable to make the secondary winding from several parallel wires with the same general cross-section. It is more convenient to carry out winding together. While one, trying not to damage the insulation of adjacent turns, carefully pulls and lays the wire, the other holds the free end of the future winding, protecting it from twisting. The upgraded LATR2 is placed in a protective metal casing with ventilation holes, on which there is a mounting board made of 10 mm getinax or fiberglass with a packet switch SB1, a thyristor voltage regulator (with resistor R6), an HL1 light indicator for turning on the device in the network and output terminals for welding on alternating (X2, X3) or constant (X4, X5) current. In the absence of a basic LATR2, it can be replaced with a homemade “welder” with a magnetic core made of transformer steel (core cross-section 45-50 cm2). Its primary winding should contain 250 turns of PEV2 wire with a diameter of 1.5 mm. The secondary one is no different from the one used in the modernized LATR2. At the output of the low-voltage winding, a rectifier block with power diodes VD3-VD10 is installed for DC welding. In addition to the indicated valves, more powerful analogs are also quite acceptable, for example, D122-32-1 (rectified current - up to 32 A). Power diodes and thyristors are installed on heat sinks, the area of ​​each of which is at least 25 cm2. The axis of the adjusting resistor R6 is brought out from the casing. A scale with divisions corresponding to specific values ​​of direct and alternating voltage is placed under the handle. And next to it is a table of the dependence of the welding current on the voltage on the secondary winding of the transformer and on the diameter of the welding electrode (0.8-1.5 mm). Of course, homemade electrodes made from carbon steel “wire rod” with a diameter of 0.5-1.2 mm are also acceptable. Blanks 250-350 mm long are coated liquid glass- a mixture of silicate glue and crushed chalk, leaving the 40 mm ends needed for connection to the welding machine unprotected. The coating must be thoroughly dried, otherwise it will start to “shoot” during welding. Although both alternating (terminals X2, X3) and direct (X4, X5) current can be used for welding, the second option, according to reviews from welders, is preferable to the first. Moreover, polarity plays a very important role. In particular, when applying “plus” to “ground” (the object being welded) and, accordingly, connecting the electrode to the terminal with the “minus” sign, the so-called direct polarity occurs. It is characterized by the release more heat than with reverse polarity, when the electrode is connected to the positive terminal of the rectifier, and the ground is connected to the negative terminal. Reverse polarity is used when it is necessary to reduce heat generation, for example, when welding thin sheets of metal. Almost all the energy released by the electric arc goes to the formation of a weld, and therefore the depth of penetration is 40-50 percent greater than with a current of the same magnitude, but of straight polarity. And a few more very significant features. An increase in the arc current at a constant welding speed leads to an increase in the depth of penetration. Moreover, if the work is carried out on alternating current, then the last of these parameters becomes 15-20 percent less than when using direct current reverse polarity. The welding voltage has little effect on the penetration depth. But the width of the seam depends on Ust: it increases with increasing voltage. Hence an important conclusion for those involved in, say, welding work during body repairs passenger car from thin sheet steel: best results welding with direct current of reverse polarity at a minimum (but sufficient for stable arc burning) voltage will give. The arc must be kept as short as possible, then the electrode is consumed evenly, and the depth of penetration of the metal being welded is maximum. The seam itself is clean and durable, practically free of slag inclusions. And you can protect yourself from rare splashes of the melt, which are difficult to remove after the product has cooled, by rubbing the heat-affected surface with chalk (the drops will roll off without sticking to the metal). The arc is excited (after applying the corresponding -Us to the electrode and the ground) in two ways. The essence of the first is to lightly touch the electrode to the parts being welded and then move it 2-4 mm to the side. The second method is reminiscent of striking a match on a box: sliding the electrode along the surface to be welded, it is immediately withdrawn a short distance. In any case, you need to catch the moment the arc occurs and only then, smoothly moving the electrode over the seam that forms immediately, maintain its quiet combustion. Depending on the type and thickness of the metal being welded, one or another electrode is selected. If, for example, there is a standard assortment for a St3 sheet with a thickness of 1 mm, electrodes with a diameter of 0.8-1 mm are suitable (this is what the design in question is mainly designed for). For welding work on 2-mm rolled steel, it is advisable to have both a more powerful “welder” and a thicker electrode (2-3 mm). For welding jewelry made of gold, silver, cupronickel, it is better to use a refractory electrode (for example, tungsten). You can also weld metals that are less resistant to oxidation using protection carbon dioxide. In any case, the work can be performed either with a vertically positioned electrode or tilted forward or backward. But experienced professionals claim: when welding with a forward angle (meaning an acute angle between the electrode and the finished seam), more complete penetration and a smaller width of the seam itself are ensured. Backward angle welding is recommended only for lap joints, especially when dealing with rolled profiles (angles, I-beams and channels). An important thing is the welding cable. For the device in question, it’s impossible would be better suited stranded copper (total cross-section about 20 mm2) in rubber insulation. The required quantity is two one and a half meter sections, each of which should be equipped with a carefully crimped and soldered terminal lug for connection to the “welder”. For direct connection to ground, a powerful alligator clip is used, and with the electrode, a holder resembling a three-pronged fork is used. You can also use a car cigarette lighter. It is also necessary to take care of personal safety. When electric arc welding, try to protect yourself from sparks, and even more so from splashes of molten metal. It is recommended to wear loose-fitting canvas clothing, protective gloves and a mask to protect your eyes from the harsh radiation of the electric arc (sunglasses are not suitable here). Of course, we must not forget about the “Safety Rules when performing work on electrical equipment in networks with voltages up to 1 kV.” Electricity does not forgive carelessness!

The basis of the welding machine of the first design— laboratory transformer LATR for 9 A. The casing and all fittings are removed from it, only the winding remains on the core. In the welding machine transformer it will be primary (network). This winding is insulated with two layers of electrical tape or varnished cloth. A secondary winding is wound on top of the insulation - 65 turns of wire or a set of wires with a total cross-section of 12-13 mm 2. The winding is reinforced with electrical tape.The transformer is installed on an insulating stand made of textolite or getinax inside a casing made of sheet steel or duralumin with a thickness of no more than 3 mm. Holes with a diameter of 8-10 mm are made in the casing cover, on the back and side walls for ventilation. A handle made of steel rod is strengthened on top.

An indicator light, a 220 V, 9 A switch and secondary winding terminals are installed on the front panel - a cable with an electrode holder is connected to one of them, and a cable is connected to the other, the second end of which is pressed against the part being welded during welding. In addition, this last terminal must be grounded during operation. The AC indicator light type CH-1, CH-2, M.N-5 signals that the device is turned on.

Electrodes for this device must have a diameter of no more than 1.5 mm.

For welding machine of the second design(Fig. 126) it is necessary to make a transformer. A core with a cross section of about 45 cm 2 is assembled from W-shaped transformer iron, and the primary (network) winding is wound on it - 220 turns of 1.5 mm PEL wire. Taps are made from the 190th and 205th turns, after which the winding is insulated with two or three layers of electrical tape or varnished cloth.

A secondary winding is wound on top of the insulated primary winding.

It contains 65 turns of wire or a set of wires with a total cross-section of 25-35 mm 2. In the set it is best to use wires of the PEL or PEV type 1.0-1.5 mm. As in the first design, the finished transformer is mounted on an insulating stand and placed in a casing. The walls of the casing must be at least 30 mm away from the transformer. On the front panel, in addition to the light bulb, switch and terminals, there is a switch that regulates the current.

In a welding machine of this design, electrodes with a diameter of 1.5 and 2 mm can be used.

When working, you must wear a mask. Connect this device to home network is not possible, since it consumes about 3 kW. You can use the device in a workshop if there is an electrical network to which you can connect devices with a power of up to 5 kW.

Attention! Before starting work, check the grounding.

Wear dry tarpaulin overalls and gloves when welding. Place a rubber mat under your feet. Don't work without a mask.