Make a welder out of a transformer. How to make a welding machine with your own hands: a step-by-step description of how to calculate and assemble a welding machine (110 photos)

It is very convenient to work in any metal processing workshop if you have a welding machine at hand. With it, you can securely connect metal parts or structures, cut holes, or even simply cut blanks in the right place.

You can make such a useful tool with your own hands, the main thing is to understand everything well, and the skill to make a beautiful and reliable seam will come with experience.

AC output current

At home, in the country, at work, such devices are most often found. Many photos of welding equipment show that it is made by hand.

The most important components for such an apparatus are a wire for two windings and a core for them. In fact, this is a transformer for lowering the voltage.

Wire dimensions

The device will work quite well with an output voltage of 60 volts and a current of up to 160 amperes. Calculations show that for the primary winding, you need to take a copper wire with a cross section of 3, and preferably 7 square millimeters. For aluminum wire, the cross section should be 1.6 times larger.

Wire insulation must be fabric because the wires get very hot during operation and the plastic will simply melt.

It is necessary to lay the primary winding very carefully and carefully because it has many turns and is located in a high voltage zone. It is desirable that the wire be without breaks, but if the required length is not at hand, then the pieces must be securely connected and soldered.

Secondary winding

For the secondary winding, you can take copper, or aluminum. The wire can be either single-core or consisting of several conductors. Cross section from 10 to 24 square millimeters.

It is very convenient to wind the coil separately from the core, for example, on a wooden blank, and then collect transformer steel plates into a finished, reliably insulated winding.

stranded wire

How to make a stranded wire of a suitable cross section for a welding machine? There is such a way. At a distance of 30 meters (more or less, depending on the calculations), two hooks are securely attached. Between them, the required amount of thin wire is stretched, from which a stranded conductor will be composed. Then one end is removed from the hook and inserted into an electric drill.

At low speeds, the wire bundle twists evenly, its total length will decrease somewhat. Clean the ends of the wire (separately each core), tin and solder well. Then insulate the entire wire, preferably with a textile-based insulating material.

Core

Good performance is shown by home-made welding machines based on transformer steel cores. They are recruited from plates with a thickness of 0.35-0.55 millimeters.

It is important to choose the right size of the window in the core so that both coils fit in it, and the cross-sectional area (its thickness) is 35-50 square centimeters. Bolts are installed at the corners of the finished core, and everything is tightly tightened with nuts.

The primary winding consists of 215 turns. To be able to regulate the welding current of the finished machine, conclusions can be drawn from winding on 165 and 190 turns.

All contacts are mounted on a plate of insulating material and signed. The scheme is as follows: the more turns of the coil, the greater the current at the output. The secondary winding consists of 70 turns.

inverter

You can assemble another welding device with your own hands - this is an inverter. It has a number of positive differences from the transformer. The very first thing that catches your eye is its light weight. Just a few kilos. You can work without removing the device from your shoulder. Then, working direct current, this allows you to create a more accurate seam, and the arc does not jump so much. Easier for beginner welders.

Parts for assembling such a device are sold in stores and on the market. You just need to know the label. The quality of the transistors requires special attention because they are in the most stressed area of ​​​​the inverter design circuit. To cool the device, forced ventilation is used in the form of cooling radiators and exhaust fans.

Thus, if you compile a catalog of home-made welding machines, you will get a long list of transformers of various designs, inverters, semi-automatic welding machines and automatic machines. Such devices allow you to work with cast iron and steel, aluminum and copper, stainless steel and thin sheet iron.

The reliability and durability of their work depends on the accuracy of calculations, the availability of materials, parts, correct assembly, as well as compliance with safety rules at all stages of the creation and operation of such devices.

Photo of a welding machine at home

Housework always requires a certain set of tools, fixtures, as well as a variety of equipment. This is especially felt by the owners of private houses and those involved in various types of repairs in their own workshops and garages. The acquisition of expensive equipment is not always justified, since its use will not be permanent, but every craftsman is quite capable of assembling a welding machine with his own hands.

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

This electric device is useful not only for welders who perform some work at home or in the garage, but also for ordinary craftsmen who use a welding device to build various devices.

Features of homemade transformers

Self-assembled devices differ from factory equipment in their technical design. Do-it-yourself welding is made from available elements and assemblies, for which a welding transformer circuit is used. With exact observance of the parameters of the component parts, the electric device will serve reliably for many years. Before you make a welding transformer device with your own hands, you need to decide on the available components. The basis is a transformer consisting of a magnetic circuit, as well as primary and secondary windings. It can be purchased separately, adapted to an existing one, or made independently. To make a welded electric device with your own hands, transformer iron and wire for windings will be added to the variety of tools from improvised materials. The manufactured transformer must be able to connect to a 220 V household power supply and have an output voltage of about 60-65 V for welding thick metals.

Features of homemade rectifiers

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

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

Depending on the goals, you can independently build a mini welded electric device. It will perfectly cope with metals of small thickness, which do not require the use of high currents when connecting. A spotter can be made from a welded electric device, which will greatly expand the possibilities of its application.

How to make a welding machine

A self-made electric welding device is designed to perform small jobs around the house, household or in the garage. At the first stage, the necessary calculations are performed and assembly parts and assemblies are prepared. To assemble a welding transformer with your own hands, it is advisable to determine in advance the place of assembly of the device. This will streamline the manufacturing process. Next to it, the layout units are folded, allowing you to assemble the simplest electric welding machine with your own hands. In addition to the main voltage converter, you will need a choke that can be used from the elements of a fluorescent lamp. In the absence of a finished element, it is made independently from a magnetic circuit from a powerful starter and wire from copper conductors with a cross section of about 1 mm square. A self-made electric welding machine will differ from its counterparts not only in appearance, but also in characteristics. To decide how to make it, check out similar devices in the photo or video.

Calculation of the welding transformer

Electric welding home-made devices are made according to the simplest scheme, which does not involve the use of additional nodes. The power of the assembled electric apparatus will depend on the required value of the welded electric current. Welding in the country with a do-it-yourself electric device will directly depend on the technical characteristics of your own product.

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

To obtain the winding values ​​\u200b\u200bof the lowest voltage of the transformer, you will have to spend a little more time. The size of the cross section of the secondary winding depends on the density of the welded electric current. For values ​​​​of 200 A, this will be 6 A / mm sq., With numbers 110-150 A - up to 8, and up to 100 A - 10. When determining the cross section of the lower winding, the strength of the welded electric current is divided by density, after which it is multiplied by 1.13.

The number of turns is calculated by dividing the cross-sectional area of ​​the transformer magnetic circuit by 50. In addition, the output voltage will affect the final result of welding. It affects the characteristic of the process and can be increasing in current, gently sloping or steeply falling. This affects the fluctuations of the arc during operation, in which the minimum current changes are important when working at home.

Scheme of the welding transformer

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

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

a - network winding on two sides of the core;
b - the corresponding secondary (welding) winding, connected in anti-parallel;
c - network winding on one side of the core;
g - the secondary winding corresponding to it, connected in series.

Defining parameters

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

Rated operating mode

Before welding, it is necessary to determine its future nominal mode of use. It shows how long do-it-yourself welding fixtures can continuously cook and how much they must cool. This indicator is also called the duration of the inclusion. For homemade electrical appliances, it is located in the region of 30%. This means that out of 10 minutes, he is able to continuously work 3, and rest 7 minutes.

Rated operating voltage

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

Mains voltage and number of phases

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

Open circuit voltage

A do-it-yourself household welder must have an x ​​/ x voltage value sufficient to ignite an electric arc. The larger this value, the easier it will appear. The manufacture of the device must comply with current safety regulations, which limit the output voltage to a maximum of 80 V.

Rated welding current of the transformer

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

Assembly process

The manufacture of a home-made welding machine begins with the necessary calculations. The input and output voltages, as well as the required electric current, are taken into account. The size of the device and the amount of materials needed directly depend on this. An electric welding machine, like other equipment, is not very difficult to make with your own hands. With the right calculation and the use of high-quality components, it can reliably serve for decades. For the base, a wire with copper conductors is used, as well as a core made of magnetically permeable iron. The remaining components are not so significant and can be selected from those that can be easily obtained.

How to start the preparatory stage

After the calculation part is completed, materials are prepared, and a workplace is equipped for assembling the structure. To build a home-made welding machine, you will need wires for the primary as well as the secondary winding, for the core - a suitable transformer iron, insulating materials (varnished cloth, textolite, glass tape, electric cardboard). In addition, you should take care of the winding machine for the manufacture of windings, metal elements for the frame and a switching electric device in advance. During the assembly process, you will need a set of conventional locksmith tools. Choose a more spacious workplace to freely wind the coils and engage in the assembly process.

Construction assembly

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

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

A wire with heat-resistant insulation is wound onto the resulting frames. This will protect the product from possible breakdown during overheating in operation. It is necessary to accurately count the number of turns so that there is no difference with the calculated values. Each wound layer is necessarily isolated from the next. Reinforced insulation is laid between the primary and secondary windings. Remember to make the necessary taps on the required number of turns. After winding is completed, external insulation is performed.

At the next stage, the wound windings are mounted on the transformer core, and its blending is performed (assembly of a single structure). At the same time, it is undesirable to drill sheets of transformer iron during installation. Metal plates are connected in a checkerboard pattern and are well tightened. Assembling a simple U-shaped welder with your own hands is not particularly difficult. At the end of the assembly procedure, the integrity of the windings is checked for possible damage. The final stage is the assembly of the case and the connection of the switching electric device. Additional equipment includes a rectifier unit, as well as an electric current regulator.

Be attentive to all processes, from calculations to the assembly of home-made welding. The final parameters of the manufactured device will depend on this.

Do-it-yourself welding in this case does not mean welding technology, but home-made equipment for electric welding. Work skills are acquired through work experience. Of course, before going to the workshop, you need to learn the theoretical course. But it can only be put into practice if you have something to work on. This is the first argument in favor of, independently mastering the welding business, first take care of the availability of appropriate equipment.

The second - a purchased welding machine is expensive. Rent is also not cheap, because. the probability of its failure with unskilled use is high. Finally, in the outback, getting to the nearest point where you can rent a welder can be just long and difficult. All in all, it is better to start the first steps in metal welding with the manufacture of a welding machine with your own hands. And then - let him stand in a barn or garage until the case. It's never too late to spend money on branded welding, if things go well.

What will we be about

This article discusses how to make equipment at home for:

• Electric arc welding with alternating current of industrial frequency 50/60 Hz and direct current up to 200 A. This is enough to weld metal structures up to about a fence from a corrugated board on a frame from a professional pipe or a welded garage.
• Microarc welding of strands of wires is very simple, and useful when laying or repairing electrical wiring.
• Spot pulse resistance welding - can be very useful when assembling products from a thin steel sheet.

What we won't talk about

First, skip the gas welding. Equipment for it costs pennies compared to consumables, gas cylinders cannot be made at home, and a home-made gas generator is a serious risk to life, plus carbide is now, where it is still on sale, expensive.

The second is inverter arc welding. Indeed, a semi-automatic welding inverter allows a novice amateur to cook quite important structures. It is light and compact and can be carried by hand. But the retail purchase of inverter components, which allows you to consistently conduct a high-quality seam, will cost more than a finished device. And with simplified homemade products, an experienced welder will try to work, and refuse - “Give me a normal device!” Plus, or rather minus - to make a more or less decent welding inverter, you need to have a fairly solid experience and knowledge in electrical engineering and electronics.

The third is argon-arc welding. From whose light hand the assertion that it is a hybrid of gas and arc went for a walk is unknown. In fact, this is a kind of arc welding: the inert gas argon does not participate in the welding process, but creates a cocoon around the working area, isolating it from the air. As a result, the welding seam is chemically clean, free from impurities of metal compounds with oxygen and nitrogen. Therefore, non-ferrous metals can be boiled under argon, incl. heterogeneous. In addition, it is possible to reduce the welding current and arc temperature without compromising its stability and to weld with a non-consumable electrode.

It is quite possible to make equipment for argon-arc welding at home, but gas is very expensive. It is unlikely that you will need to cook aluminum, stainless steel or bronze in the order of routine economic activity. And if you really need it, it’s easier to rent argon welding - compared to how much (in money terms) the gas will go back into the atmosphere, these are pennies.

Transformer

The basis of all "our" types of welding is a welding transformer. The procedure for its calculation and design features differ significantly from those of power supply (power) and signal (sound) transformers. The welding transformer operates in intermittent mode. If you design it for maximum current like continuous transformers, it will turn out to be prohibitively large, heavy and expensive. Ignorance of the features of electrical transformers for arc welding is the main reason for the failure of amateur designers. Therefore, we will walk through the welding transformers in the following order:

1. a little theory - on the fingers, without formulas and zaumi;
2. features of the magnetic circuits of welding transformers with recommendations for choosing from randomly turned up ones;
3. testing of available second-hand;
4. calculation of a transformer for a welding machine;
5. preparation of components and winding of windings;
6. trial assembly and fine-tuning;
7. commissioning.

Theory

An electrical transformer can be likened to a water storage tank. This is a rather deep analogy: the transformer operates due to the energy reserve of the magnetic field in its magnetic circuit (core), which can many times exceed that instantly transferred from the power supply network to the consumer. And the formal description of losses due to eddy currents in steel is similar to that for water losses due to infiltration. Electricity losses in copper windings are formally similar to pressure losses in pipes due to viscous friction in a liquid.

Note: the difference is in evaporation losses and, accordingly, magnetic field scattering. The latter in the transformer are partially reversible, but they smooth out the peaks of energy consumption in the secondary circuit.

An important factor in our case is the external current-voltage characteristic (VVC) of the transformer, or simply its external characteristic (VX) - the dependence of the voltage on the secondary winding (secondary) on the load current, with a constant voltage on the primary winding (primary). For power transformers, the VX is rigid (curve 1 in the figure); they are like a shallow vast pool. If it is properly insulated and covered with a roof, then the water loss is minimal and the pressure is quite stable, no matter how the consumers turn the taps. But if there is a gurgle in the drain - sushi paddles, the water is drained. With regard to transformers, the power engineer must keep the output voltage as stable as possible up to a certain threshold, less than the maximum instantaneous power consumption, be economical, small and light. For this:

• The steel grade for the core is chosen with a more rectangular hysteresis loop.
• Constructive measures (core configuration, calculation method, winding configuration and arrangement) in every possible way reduce dissipation losses, losses in steel and copper.
• The induction of the magnetic field in the core is taken less than the maximum allowable for the transfer of the current form, because. its distortion reduces the efficiency.

Note: transformer steel with "angular" hysteresis is often referred to as magnetically hard. This is not true. Hard magnetic materials retain strong residual magnetization, they are made by permanent magnets. And any transformer iron is magnetically soft.

It is impossible to cook from a transformer with a rigid VX: the seam is torn, burnt, the metal is splashed. The arc is inelastic: I almost moved the electrode in the wrong way, it goes out. Therefore, the welding transformer is already made similar to a conventional water tank. Its VC is soft (normal dissipation, curve 2): as the load current increases, the secondary voltage drops smoothly. The normal scattering curve is approximated by a straight line falling at an angle of 45 degrees. This allows, due to a decrease in efficiency, to briefly remove several times more power from the same iron, or, respectively. reduce the weight and size of the transformer. In this case, the induction in the core can reach the saturation value, and even exceed it for a short time: the transformer will not go into a short circuit with zero power transfer, like a “silovik”, but will begin to heat up. Quite long: thermal time constant of welding transformers 20-40 min. If you then let it cool down and there was no unacceptable overheating, you can continue to work. The relative drop in the secondary voltage ΔU2 (corresponding to the range of arrows in the figure) of normal dissipation gradually increases with an increase in the range of oscillations of the welding current Iw, which makes it easy to hold the arc in any type of work. These properties are provided as follows:

1. The steel of the magnetic circuit is taken with a hysteresis, more "oval".
2. The reversible scattering losses are normalized. By analogy: the pressure has dropped - consumers will not pour out a lot and quickly. And the operator of the water utility will have time to turn on the pumping.
3. The induction is chosen close to the limiting overheating, this allows, by reducing cosφ (a parameter equivalent to efficiency) at a current that is significantly different from sinusoidal, to take more power from the same steel.

Note: reversible scattering loss means that part of the lines of force penetrates the secondary through the air, bypassing the magnetic circuit. The name is not entirely successful, as well as "useful scattering", because. "Reversible" losses are no more useful for the efficiency of a transformer than irreversible ones, but they soften the VX.

As you can see, the conditions are completely different. So, is it necessary to look for iron from a welder? Optional, for currents up to 200 A and peak power up to 7 kVA, and this is enough on the farm. By calculation and constructive measures, as well as with the help of simple additional devices (see below), we will obtain, on any hardware, a BX curve 2a that is somewhat more rigid than the normal one. In this case, the efficiency of welding energy consumption is unlikely to exceed 60%, but for episodic work, this is not a problem for yourself. But on fine work and low currents, it will not be difficult to hold the arc and welding current, without having much experience (ΔU2.2 and Ib1), at high currents Ib2 we will get an acceptable weld quality, and it will be possible to cut metal up to 3-4 mm.

There are also welding transformers with a steeply falling VX, curve 3. This is more like a booster pump: either the output flow is at the nominal value, regardless of the feed height, or it does not exist at all. They are even more compact and light, but in order to withstand the welding mode at a steeply falling VX, it is necessary to respond to fluctuations ΔU2.1 of the order of a volt in a time of the order of 1 ms. Electronics can do this, so transformers with a "cool" VX are often used in semi-automatic welding machines. If you cook from such a transformer manually, then the seam will go sluggish, undercooked, the arc is again inelastic, and when you try to light it again, the electrode sticks every now and then.

Magnetic circuits

Types of magnetic circuits suitable for the manufacture of welding transformers are shown in fig. Their names begin with a letter combination respectively. size. L means tape. For a welding transformer L or without L, there is no significant difference. If there is M in the prefix (SLM, PLM, SMM, PM) - ignore without discussion. This is iron of reduced height, unsuitable for a welder with all other outstanding advantages.

The letters of the nominal value are followed by numbers denoting a, b and h in fig. For example, for Sh20x40x90, the cross-sectional dimensions of the core (central rod) are 20x40 mm (a * b), and the window height h is 90 mm. Cross-sectional area of ​​the core Sc = a*b; window area Sok = c * h is needed for accurate calculation of transformers. We will not use it: for an accurate calculation, you need to know the dependence of losses in steel and copper on the value of induction in the core of a given size, and for them - the steel grade. Where will we get it if we wind it on random hardware? We will calculate according to a simplified method (see below), and then we will bring it up during the tests. It will take more work, but we will get welding, on which you can actually work.

Note: if the iron is rusty from the surface, then nothing, the properties of the transformer will not suffer from this. But if there are spots of tarnishing colors on it, this is a marriage. Once this transformer overheated very much and the magnetic properties of its iron deteriorated irreversibly.

Another important parameter of the magnetic circuit is its mass, weight. Since the specific gravity of the steel is unchanged, it determines the volume of the core, and, accordingly, the power that can be taken from it. For the manufacture of welding transformers, magnetic cores with a mass of:

• O, OL - from 10 kg.
• P, PL - from 12 kg.
• W, WL - from 16 kg.

Why Sh and ShL are needed harder is understandable: they have an “extra” side rod with “shoulders”. OL can be lighter, because it does not have corners that require excess iron, and the bends of the magnetic lines of force are smoother and for some other reasons, which are already in the next. section.

Oh OL

The cost of transformers on tori is high due to the complexity of their winding. Therefore, the use of toroidal cores is limited. A torus suitable for welding can, firstly, be removed from LATR - a laboratory autotransformer. Laboratory, which means it should not be afraid of overloads, and the LATR iron provides a VX close to normal. But…

LATR is a very useful thing, first. If the core is still alive, it is better to restore the LATR. Suddenly you don’t need it, you can sell it, and the proceeds will be enough for welding suitable for your needs. Therefore, it is difficult to find “bare” LATR cores.

The second is that LATRs with a power of up to 500 VA for welding are weak. From iron LATR-500, it is possible to achieve welding with an electrode 2.5 in the mode: cook for 5 minutes - it cools down for 20 minutes, and we heat up. As in the satire of Arkady Raikin: mortar bar, brick yok. Brick bar, mortar yok. LATRs 750 and 1000 are very rare and fit.

Another torus suitable for all properties is the stator of an electric motor; welding from it will turn out at least for an exhibition. But finding it is no easier than LATR's iron, and winding it up is much more difficult. In general, a welding transformer from an electric motor stator is a separate issue, there are so many complexities and nuances. First of all - with the winding of a thick wire on a "donut". Having no experience in winding toroidal transformers, the probability of damaging an expensive wire and not getting welding is close to 100%. Therefore, alas, it will be necessary to wait a little with the cooking apparatus on a triad transformer.

SH, SHL

Armor cores are structurally designed for minimal scattering, and it is practically impossible to normalize it. Welding on a regular Sh or ShL will be too hard. In addition, the cooling conditions of the windings on Sh and ShL are the worst. The only armored cores suitable for a welding transformer are of increased height with spaced biscuit windings (see below), on the left in fig. The windings are separated by dielectric non-magnetic heat-resistant and mechanically strong gaskets (see below) with a thickness of 1/6-1/8 of the core height.

The core Ш is shifted (assembled from plates) for welding necessarily overlapped, i.e. yoke-plate pairs are alternately oriented back and forth relative to each other. The method of normalizing scattering by a non-magnetic gap for a welding transformer is unsuitable, because the loss is irreversible.

If a laminated Ш turns up without a yoke, but with a punching of the plates between the core and the jumper (in the center), you are in luck. The plates of signal transformers are mixed, and the steel on them, to reduce signal distortion, goes giving a normal VX initially. But the probability of such luck is very small: signal transformers for kilowatt power are a rare curiosity.

Note: do not try to assemble a high W or WL from a pair of ordinary ones, as on the right in fig. A continuous direct gap, albeit a very thin one, is irreversible scattering and a steeply falling VX. Here, the dispersion losses are almost similar to the losses of water due to evaporation.

PL, PLM

Rod cores are most suitable for welding. Of these, they are laminated in pairs of identical L-shaped plates, see Fig., Their irreversible scattering is the smallest. Secondly, the windings of P and Plov are wound in exactly the same halves, half turns for each. The slightest magnetic or current asymmetry - the transformer buzzes, heats up, but there is no current. The third thing that may seem non-obvious to those who have not forgotten the school rule of the gimlet is that the windings on the rods are wound in one direction. Does something not seem right? Does the magnetic flux in the core have to be closed? And you twist the gimlets according to the current, and not according to the turns. The directions of the currents in the half-windings are opposite, and the magnetic fluxes are shown there. You can also check if the wiring protection is reliable: apply the network to 1 and 2 ', and close 2 and 1 '. If the machine does not immediately knock out, then the transformer will howl and shake. However, who knows what you have with the wiring. Better not.

Note: you can still find recommendations - to wind the windings of the welding P or PL on different rods. Like, VX softens. That's how it is, but for this you need a special core, with rods of different sections (secondary on a smaller one) and notches that release lines of force into the air in the right direction, see fig. on right. Without this, we get a noisy, shaky and gluttonous, but not a cooking transformer.

If there is a transformer

A 6.3 A circuit breaker and an AC ammeter will also help determine the suitability of an old welder lying around God knows where and the devil knows how. An ammeter is needed either a non-contact induction (current clamp), or a 3 A electromagnetic pointer. the shape of the current in the circuit will be far from sinusoidal. Another is a liquid household thermometer with a long neck, or, better, a digital multimeter with the ability to measure temperature and a probe for this. The step-by-step procedure for testing and preparing for further operation of the old welding transformer is as follows:

Calculation of the welding transformer

In Runet, you can find different methods for calculating welding transformers. With apparent inconsistency, most of them are correct, but with full knowledge of the properties of steel and / or for a specific range of magnetic core ratings. The proposed methodology was developed in Soviet times, when there was a shortage of everything instead of a choice. For the transformer calculated from it, the VX drops a little steeply, somewhere between curves 2 and 3 in Fig. at the beginning. This is suitable for cutting, and for thinner work, the transformer is supplemented with external devices (see below), which stretch the VX along the current axis to curve 2a.

The calculation basis is usual: the arc stably burns under voltage Ud 18-24 V, and its ignition requires an instantaneous current 4-5 times greater than the nominal welding current. Accordingly, the minimum open-circuit voltage Uxx of the secondary will be 55 V, but for cutting, since everything possible is squeezed out of the core, we take not the standard 60 V, but 75 V. Nothing more: it’s unacceptable according to TB, and the iron will not pull out. Another feature, for the same reasons, is the dynamic properties of the transformer, i.e. its ability to quickly switch from a short circuit mode (say, when shorted by metal drops) to a working one, is maintained without additional measures. True, such a transformer is prone to overheating, but since it is our own and in front of our eyes, and not in the far corner of a workshop or site, we will consider this acceptable. So:

• According to the formula from paragraph 2 before. the list we find the overall power;
• We find the maximum possible welding current Iw \u003d Pg / Ud. 200 A are provided if 3.6-4.8 kW can be removed from the iron. True, in the 1st case, the arc will be sluggish, and it will be possible to cook only with a deuce or 2.5;
• We calculate the operating current of the primary at the maximum network voltage allowed for welding I1rmax \u003d 1.1Pg (VA) / 235 V. In general, the norm for the network is 185-245 V, but for a home-made welder at the limit, this is too much. We take 195-235 V;
• Based on the found value, we determine the tripping current of the circuit breaker as 1.2I1рmax;
• We accept the current density of the primary J1 = 5 A/sq. mm and, using I1rmax, we find the diameter of its copper wire d = (4S / 3.1415) ^ 0.5. Its full diameter with self-isolation D = 0.25 + d, and if the wire is ready - tabular. To work in the "brick bar, mortar yok" mode, you can take J1 \u003d 6-7 A / sq. mm, but only if the required wire is not available and is not expected;
• We find the number of turns per volt of the primary: w = k2 / Sс, where k2 = 50 for W and P, k2 = 40 for PL, SHL and k2 = 35 for O, OL;
• We find the total number of its turns W = 195k3w, where k3 = 1.03. k3 takes into account the energy losses of the winding due to leakage and in copper, which is formally expressed by a somewhat abstract parameter of the winding's own voltage drop;
• We set the stacking factor Ku = 0.8, add 3-5 mm to a and b of the magnetic circuit, calculate the number of winding layers, the average length of the coil and the wire footage
• We calculate the secondary in the same way at J1 = 6 A/sq. mm, k3 \u003d 1.05 and Ku \u003d 0.85 for voltages of 50, 55, 60, 65, 70 and 75 V, in these places there will be taps for rough adjustment of the welding mode and compensation for fluctuations in the supply voltage.

Winding and finishing

The diameters of the wires in the calculation of the windings are usually obtained more than 3 mm, and varnished winding wires with d> 2.4 mm are rare in wide sale. In addition, the welder's windings experience strong mechanical loads from electromagnetic forces, so finished wires are needed with an additional textile winding: PELSh, PELSHO, PB, PBD. Finding them is even more difficult, and they are very expensive. The footage of the wire per welder is such that cheaper bare wires can be insulated on their own. An additional advantage is that by twisting several stranded wires to the desired S, we get a flexible wire, which is much easier to wind. Anyone who has tried to manually lay a tire on the frame at least 10 squares will appreciate it.

isolation

Let's say there is a wire of 2.5 square meters. mm in PVC insulation, and the secondary needs 20 m per 25 squares. We prepare 10 coils or coils of 25 m each. We unwind about 1 m of wire from each and remove the standard insulation, it is thick and not heat-resistant. We twist the bare wires with a pair of pliers into an even tight braid, and wrap it around, in order of increasing cost of insulation:

1. Masking tape with an overlap of turns of 75-80%, i.e. in 4-5 layers.
2. Muslin braid with an overlap of 2/3-3/4 turns, i.e. 3-4 layers.
3. Cotton tape with an overlap of 50-67%, in 2-3 layers.

Note: the wire for the secondary winding is prepared and wound after winding and testing the primary, see below.

winding

A thin-walled home-made frame will not withstand the pressure of thick wire turns, vibrations and jerks during operation. Therefore, the windings of welding transformers are made frameless biscuit, and on the core they are fixed with wedges made of textolite, fiberglass or, in extreme cases, impregnated with liquid varnish (see above) bakelite plywood. The instruction for winding the windings of the welding transformer is as follows:

• We are preparing a wooden boss with a height in winding height and with dimensions in diameter 3-4 mm larger than a and b of the magnetic circuit;
• We nail or fasten temporary plywood cheeks to it;
• We wrap the temporary frame in 3-4 layers with a thin plastic film with a call on the cheeks and a twist on their outer side so that the wire does not stick to the tree;
• We wind a pre-insulated winding;
• After winding, we impregnate twice until it flows through with liquid varnish;
• after the impregnation dries, carefully remove the cheeks, squeeze out the boss and tear off the film;
• we tightly tie the winding in 8-10 places evenly around the circumference with thin cord or propylene twine - it is ready for testing.

Finishing and domotka

We shift the core into a biscuit and tighten it with bolts, as expected. The winding tests are carried out in exactly the same way as those of the dubious finished transformer, see above. It is better to use LATR; Iхх at an input voltage of 235 V should not exceed 0.45 A per 1 kVA of the overall power of the transformer. If more, the primary is homemade. Winding wire connections are made on bolts (!), insulated with a heat-shrinkable tube (HERE) in 2 layers or cotton tape in 4-5 layers.

According to the test results, the number of turns of the secondary is corrected. For example, the calculation gave 210 turns, but in reality Ixx got back to normal at 216. Then we multiply the calculated turns of the secondary sections by 216/210 = 1.03 approx. Do not neglect the decimal places, the quality of the transformer largely depends on them!

After finishing, we disassemble the core; we tightly wrap the biscuit with the same masking tape, calico or “rag” electrical tape in 5-6, 4-5 or 2-3 layers, respectively. Wind across the turns, not along them! Now once again impregnate with liquid varnish; when dry - twice undiluted. This biscuit is ready, you can make a secondary one. When both are on the core, we once again test the transformer for Ixx (suddenly it curled somewhere), fix the biscuits and impregnate the entire transformer with normal varnish. Phew, the most dreary part of the work is over.

Pull VX

But he is still too cool with us, remember? Needs to be softened. The simplest way - a resistor in the secondary circuit - does not suit us. Everything is very simple: at a resistance of only 0.1 ohms at a current of 200, 4 kW of heat will be dissipated. If we have a welder for 10 or more kVA, and we need to weld thin metal, a resistor is needed. Whatever the current is set by the regulator, its emissions when the arc is ignited are inevitable. Without an active ballast, they will burn the seam in places, and the resistor will extinguish them. But to us, low-powered ones, he will not be of any use to him.

The reactive ballast (inductor, choke) will not take away excess power: it will absorb current surges, and then smoothly give them to the arc, this will stretch the VX as it should. But then you need a choke with dissipation control. And for him - the core is almost the same as that of the transformer, and rather complex mechanics, see fig.

We will go the other way: we will use an active-reactive ballast, colloquially referred to as the gut by old welders, see fig. on right. Material - steel wire rod 6 mm. The diameter of the turns is 15-20 cm. How many of them are shown in fig. it can be seen that for power up to 7 kVA this gut is correct. The air gaps between the turns are 4-6 cm. The active-reactive choke is connected to the transformer with an additional piece of welding cable (hose, simply), and the electrode holder is attached to it with a clip-clothespin. By selecting the connection point, it is possible, together with switching to secondary outlets, to fine-tune the operating mode of the arc.

Note: an active-reactive inductor can get red hot in operation, so it needs a fireproof, heat-resistant, non-magnetic dielectric lining. In theory, a special ceramic lodgment. It is acceptable to replace it with a dry sand cushion, or already formally with a violation, but not rough, the welding gut is laid on bricks.

But other?

This means, first of all, an electrode holder and a connection device for the return hose (clamp, clothespin). They, since we have a transformer at the limit, need to be bought ready-made, but such as in fig. right, don't. For a 400-600 A welding machine, the quality of the contact in the holder is not very noticeable, and it will also withstand simply winding the return hose. And our self-made, working with an effort, can go wrong, it seems to be unclear why.

Next, the body of the device. It must be made from plywood; preferably Bakelite impregnated as described above. The bottom is from 16 mm thick, the panel with the terminal block is from 12 mm, and the walls and cover are from 6 mm, so that they do not come off when carrying. Why not sheet steel? It is a ferromagnet and in the stray field of a transformer it can disrupt its operation, because. we get everything we can out of it.

As for the terminal blocks, the very terminals are made from bolts from M10. The basis is the same textolite or fiberglass. Getinax, bakelite and carbolite are not suitable, they will crumble, crack and delaminate pretty soon.

Trying a constant

DC welding has a number of advantages, but the VX of any DC welding transformer is tightened. And ours, designed for the minimum possible power reserve, will become unacceptably tough. The inductor-gut will not help here, even if it worked on direct current. In addition, expensive 200 A rectifier diodes must be protected from current and voltage surges. We need a return-absorbing filter of infra-low frequencies, Finch. Although it looks reflective, you need to take into account the strong magnetic connection between the halves of the coil.

The scheme of such a filter, known for many years, is shown in Fig. But immediately after its introduction by amateurs, it turned out that the operating voltage of the capacitor C is small: voltage surges during ignition of the arc can reach 6-7 values ​​of its Uxx, i.e. 450-500 V. Further, capacitors are needed to withstand the circulation of large reactive power, only and only oil-paper (MBGCH, MBGO, KBG-MN). About the mass and dimensions of single "cans" of these types (by the way, and not cheap) gives an idea of ​​the following. fig., and the battery will need 100-200 of them.

With a magnetic circuit, the coil is simpler, although not quite. For it, 2 PLA of the TS-270 power transformer from old tube TVs-"coffins" (the data is available in reference books and in Runet), or similar, or SL with similar or large a, b, c and h. From 2 PLs, a SL is assembled with a gap, see Fig., 15-20 mm. Fix it with textolite or plywood gaskets. Winding - insulated wire from 20 sq. mm, how much will fit in the window; 16-20 turns. They wind it in 2 wires. The end of one is connected to the beginning of the other, this will be the middle point.

The filter is adjusted along the arc at the minimum and maximum Uхх values. If the arc is sluggish at the minimum, the electrode sticks, the gap is reduced. If the metal burns at the maximum, increase it or, which will be more efficient, cut off part of the side rods symmetrically. So that the core does not crumble from this, it is impregnated with liquid, and then with normal varnish. Finding the optimum inductance is quite difficult, but then welding works flawlessly on alternating current.

microarc

The purpose of microarc welding is said at the beginning. The “equipment” for it is extremely simple: a step-down transformer 220 / 6.3 V 3-5 A. In tube times, radio amateurs were connected to the filament winding of a regular power transformer. One electrode - the twisting of wires itself (copper-aluminum, copper-steel can be used); the other is a graphite rod like a lead from a 2M pencil.

Now more computer power supplies are used for microarc welding, or, for pulsed microarc welding, capacitor banks, see the video below. At direct current, the quality of work, of course, improves.

Video: homemade twist welding machine

Video: do-it-yourself welding machine from capacitors

Contact! There is a contact!

Contact welding in industry is mainly used for spot, seam and butt welding. At home, primarily in terms of energy consumption, a pulsed point is feasible. It is suitable for welding and welding thin, from 0.1 to 3-4 mm, steel sheet parts. Arc welding will burn through a thin wall, and if the part is a coin or less, then the softest arc will burn it entirely.

The principle of contact spot welding is illustrated in Fig: copper electrodes compress parts with force, a current pulse in the steel-steel ohmic resistance zone heats the metal to the point where electrodiffusion occurs; metal does not melt. This requires approx. 1000 A per 1 mm thickness of the parts to be welded. Yes, a current of 800 A will grab sheets of 1 and even 1.5 mm. But if this is not a craft for fun, but, say, a galvanized corrugated fence, then the very first strong gust of wind will remind you: “Man, the current was rather weak!”

Nevertheless, resistance spot welding is much more economical than arc welding: the open-circuit voltage of the welding transformer for it is 2 V. It is the sum of 2-contact steel-copper potential differences and the ohmic resistance of the penetration zone. A transformer for contact welding is calculated similarly to it for arc welding, but the current density in the secondary winding is 30-50 or more A / sq. mm. The secondary of the contact-welding transformer contains 2-4 turns, it cools well, and its utilization factor (the ratio of welding time to idling and cooling time) is many times lower.

In RuNet there are many descriptions of home-made pulsed spot welders from unusable microwaves. They are, in general, correct, but in repetition, as it is written in "1001 Nights", there is no use. And old microwave ovens don't lie around in heaps. Therefore, we will deal with less well-known designs, but, by the way, more practical.

On fig. - the device of the simplest apparatus for pulsed spot welding. They can weld sheets up to 0.5 mm; for small crafts, it fits perfectly, and magnetic cores of this and larger sizes are relatively affordable. Its advantage, in addition to simplicity, is the clamping of the welding tongs running rod with a load. A third hand would not hurt to work with a contact welding impulse, and if one has to squeeze the tongs with force, then it is generally inconvenient. Disadvantages - increased accident and injury hazard. If you accidentally give an impulse when the electrodes are brought together without welded parts, then plasma will strike from the tongs, metal splashes will fly, the wiring protection will be knocked out, and the electrodes will fuse tightly.

The secondary winding is made of a 16x2 copper bus. It can be made from strips of thin sheet copper (it will turn out flexible) or made from a segment of a flattened refrigerant supply pipe for a domestic air conditioner. The tire is isolated manually, as described above.

Here in fig. - drawings of a pulsed spot welding machine are more powerful, for welding a sheet up to 3 mm, and more reliable. Thanks to a fairly powerful return spring (from the armored mesh of the bed), accidental convergence of the tongs is excluded, and the eccentric clamp provides a strong stable compression of the tongs, which significantly affects the quality of the welded joint. In which case, the clamp can be instantly reset with one blow on the eccentric lever. The disadvantage is the insulating knots of the pliers, there are too many of them and they are complex. Another one is aluminum pincer bars. Firstly, they are not as strong as steel ones, and secondly, these are 2 unnecessary contact differences. Although the heat dissipation of aluminum is certainly excellent.

About electrodes

In amateur conditions, it is more expedient to isolate the electrodes at the installation site, as shown in fig. on right. There is no conveyor at home, the apparatus can always be allowed to cool down so that the insulating sleeves do not overheat. This design will make it possible to make rods from a durable and cheap steel professional pipe, and also extend the wires (up to 2.5 m is acceptable) and use a contact welding gun or remote tongs, see fig. below.

On fig. On the right, one more feature of electrodes for resistance spot welding is visible: a spherical contact surface (heel). Flat heels are more durable, so electrodes with them are widely used in industry. But the diameter of the flat heel of the electrode must be equal to 3 thicknesses of the adjacent welded material, otherwise the penetration spot will burn out either in the center (wide heel) or along the edges (narrow heel), and corrosion will go from the welded joint even on stainless steel.

The last point about the electrodes is their material and dimensions. Red copper quickly burns out, so purchased electrodes for resistance welding are made of copper with a chromium additive. These should be used, at current copper prices it is more than justified. The diameter of the electrode is taken depending on the mode of its use, based on a current density of 100-200 A/sq. mm. The length of the electrode according to the conditions of heat transfer is at least 3 of its diameters from the heel to the root (beginning of the shank).

How to give impetus

In the simplest home-made pulse-contact welding machines, a current pulse is given manually: they simply turn on the welding transformer. This, of course, does not benefit him, and welding is either lack of fusion, or burnout. However, it is not so difficult to automate the feed and normalize the welding pulses.

A diagram of a simple, but reliable and long-term proven welding pulse shaper is shown in fig. Auxiliary transformer T1 is a conventional power transformer for 25-40 watts. Winding voltage II - according to the backlight. Instead of it, you can put 2 LEDs connected in anti-parallel with a quenching resistor (normal, 0.5 W) 120-150 Ohms, then the voltage II will be 6 V.

Voltage III - 12-15 V. It can be 24, then capacitor C1 (ordinary electrolytic) is needed for a voltage of 40 V. Diodes V1-V4 and V5-V8 - any rectifier bridges for 1 and from 12 A, respectively. Thyristor V9 - for 12 or more A 400 V. Optothyristors from computer power supplies or TO-12.5, TO-25 are suitable. Resistor R1 - wire, they regulate the pulse duration. Transformer T2 - welding.

Direct current will require a high power source of electric current, which converts the standard voltage of the household network and ensures the constancy of the value of the electric current to ignite and maintain the electric arc.

A DC welding machine has a number of advantages: soft arc ignition and the ability to connect thin-walled parts.

Block diagram of the apparatus for welding

The power supply is installed in a housing made of plastic or sheet metal. The power supply unit of the unit is equipped with all the components necessary for operation: connectors, switches, terminals and regulators. The body of the unit for welding work is equipped with special holders and wheels for transportation.

Read also:

The main condition in the design of the unit used for welding is an understanding of the principle of operation of the apparatus and the essence of the welding process itself. In order to design your own welding machine, you need to understand the principles of ignition and combustion of an electric arc and the basic principles of melting an electrode for welding.

The high power power supply includes the following components:

• rectifier;
• inverters;
• current and voltage transformer;
• regulators that improve the quality characteristics of the resulting electric arc;
• additional devices.

The main component of any welding unit is a transformer. Auxiliary devices may have a different organization scheme depending on the design of the device.

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welding transformer

The DC welding machine in its design includes a transformer as the main element, which provides a decrease in the normal mains voltage from 220 V to 45-80 V.

This structural element operates in arc mode with maximum power.

The transformers used in the design must withstand high currents during operation, the rated strength of which is 200 A. The current-voltage indicators of the transformer must fully comply with the special requirements that ensure the operating modes of arc welding.
Some homemade transformer welding machines are simple in design. They do not have additional devices for adjusting current parameters. Adjustment of the technical parameters of such a device is carried out in several ways:

• with the help of a highly specialized regulator;
• by switching the number of coil turns.

The transformer of the welding unit consists of the following structural elements:

• magnetic circuit made of transformer steel plates;
• two windings - primary and secondary, this transformer component has terminals for connecting devices for adjusting operating current parameters.

The transformer used in the welding machine does not have adjusting devices that provide current regulation and its limitation on the working winding. The primary winding of the welding transformer is equipped with terminals for connecting control circuits and devices that allow you to adjust the welding device depending on the operating conditions and the parameters of the incoming current.

The main part of the transformer is the magnetic core. Most often, when designing home-made welding machines, magnetic circuits from a decommissioned engine, an old power transformer are used. Each design of the magnetic circuit has its own nuances in the design. The main parameters characterizing the magnetic core are the following:

• the size of the magnetic circuit;
• the number of turns of windings on the magnetic circuit;
• voltage level at the input and output of the device;
• current consumption level;
• maximum current received at the output of the device.

These basic characteristics determine the suitability of the transformer for use as a device to promote the formation of an arc, as well as a device that promotes the formation of a quality weld.

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Possible details when creating a machine for welding

When creating a do-it-yourself welding machine, the stability of the electric arc is achieved by the constancy of the potential. The stability of the arc ensures the quality of the resulting seams. Potential constancy is achieved by using high-power rectifiers, which are made on diodes that can withstand currents up to 200 A, such as, for example, V-200.

These diodes are large and require the mandatory use of massive radiators to organize high-quality heat dissipation. This circumstance must be taken into account in the manufacture of the structure body. The best option when creating a design would be to use a special diode bridge. Diodes can be mounted in parallel, which allows a significant increase in output current.

Assembling the structure with your own hands, you need to adjust all its components. With poor-quality selection or incorrect calculation, the design can affect the quality of welding.

Sometimes, with an appropriate selection of parts and accessories, a truly unique device can be obtained that has soft and easy ignition of an electric arc, and parts can be welded even with very thin walls, with almost no liquid metal splashing.

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Schematic diagram of a homemade welding unit

You can make a home-made welding machine based on transistor or thyristor control. Thyristors are more reliable. These elements of the control design are capable of withstanding an output short and are able to recover from this state fairly quickly. These control system components do not require the installation of powerful cooling radiators. This is due to the fact that structural elements have low heat dissipation.

A control system based on transistors is able to get out of working condition much faster, since transistors burn out much faster when overloads occur and are more capricious in operation. The circuit created on the basis of thyristors is simple and highly reliable.

A control unit based on these elements has the following advantages:

• smooth adjustment;
• presence of direct current.

When welding steel with a thickness of 3 mm, the current consumed is about 10 A. The welding current is supplied by pressing a special lever on the plug that holds the electrode.

This design allows you to increase safety in the process of work, work with high voltage, which ensures the stability of the arc. In the case of using reverse polarity in the work, it is possible to carry out welding work with very thin sheet metal.

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

For assembly, you do not have to spend a lot of money, effort and time. Also, you do not need to purchase unreasonably expensive models of such equipment.

To make a mini welding machine with your own hands from improvised means, without much financial cost 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 current supply power of home-made equipment for welding. The connection of parts of a massive structure requires a greater current intensity, and welding work with thin metal surfaces requires a minimum.

The current value is related to the selected electrodes to be used in the process. When welding products up to 5 mm, it is necessary to use rods up to 4 mm, and in a design with 2 mm thickness, the rods should be 1.5 mm.

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

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

This equipment includes:

• magnetic core;
• winding - primary and secondary.

Also, the transformer can be made independently. For the magnetic circuit, plates made of steel or other durable material are used. The windings are necessary in order to directly perform welding work and be able to connect the welding unit to a 220 volt network.

Transformer for welding.

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

You should not go deep enough into this topic, since one of the easiest ways to assemble a do-it-yourself welding machine is.

Its feature is work with alternating current, which ensures the performance of 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 a large thickness.
2. Material for the core, which will be located in the transformer.
   The material itself must have increased permeability with magnetization.

The best option is when the core in the form of a rod 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.

Scheme of the device of the welding transformer.

However, it is worth paying attention that it is more difficult to wind the windings on this form. Best of all, when the core cross-section for classic do-it-yourself welding equipment used for domestic purposes had an area of ​​\u200b\u200babout 50 cm2.

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

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

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

The insulation is also made by hand, using cotton or fiberglass, or rather, its parts are 2 cm wide. Thanks to these pieces, it will be possible to wrap the wire, and then impregnate it with any varnish with an electrical purpose. Such insulation will not overheat after regular operation.

Similarly to the above calculations, it will be possible to calculate which cross-sectional area of ​​\u200b\u200bthe 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 4 mm in diameter.

In addition, in a simple way, you need to determine how much a piece of copper wire will stretch and how many turns it will take to wind two windings. After that, the coils are wound, and the frame is made using the geometric parameters of the magnetic circuit.

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

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

Welding Machine Manufacturing

Today it is almost impossible and rather 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 can do any work with metal products.

Scheme of a transformer with a separate choke.

To make a high-quality unit, you need to have the 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 the purpose of home use, it is best to learn how to make mini welding.

It is more convenient to call a wizard or purchase a ready-made unit, but sometimes it can be too costly, since it is quite difficult to determine the number of volts per welding machine when choosing a model for various parameters, such as the weight for the welding machine.

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

On alternating current

To make home-made welding machines, you need to select a voltage indicator, the best is 60 volts, the current is best regulated 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, the optimal size of 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 a value of 1.6.

It is worth noting that the wires must be wrapped with a rag, as they must be insulated. The fact is that as the temperature rises, the wire can melt and a short circuit will occur.

In the absence of the necessary wire, it is possible to replace it with a slightly thinner residential wire, winding it in pairs. However, it must be remembered that the winding thickness will increase, due to which the dimensions of the welding equipment will be large. Under the secondary winding, a thick wire with a large number of strands of copper is used.

DC

Electrical circuit of a DC welder.

Some welding machines work with direct current. Thanks to this unit, it is possible to 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 homemade products 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 trim the current value, you can use capacitors that have certain characteristics and voltage features. After that, the unit is assembled sequentially according to the scheme.

Chokes are used to regulate the current, and contacts to attach the holder. Additional parts are used in the transmission of 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 kindle an electric arc. This process is easy and is carried out by the following actions: we bring the tip of the electrode under a certain slope from the side of the metal coating and strike it on the surface of the structure.

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

When making a mini welding machine with your own hands, you must be guided by 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 to be welded. This distance can be equal to the cross section of the selected electrode.

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

Scheme of a simple welding machine.

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

With a small current strength indicator, the seam will come out of poor quality, but you should not set an increased value, as there is a risk of burning the surface.

If it is necessary to weld surfaces of small thickness, then the rods will fit with a size of 1 to 3 millimeters, while the current strength should vary with marks of 20-60 A. Using large-section electrodes, metal products up to 5 millimeters can be welded, however, 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 with light movements that appears on the seam, after which it is cleaned with a special brush.

Thanks to this action, you will be able to maintain a pleasant aesthetic appearance of your device. Do not worry if the cleaning of the equipment does not work out very well in the first couple. This skill is gained through experience and subject to the implementation of all recommendations for the competent operation of the structure.

Outcome

Summing up, 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.