Nowadays it is difficult to see any work with metal being carried out without the use of a welding machine. This device freely cuts or joins iron parts, regardless of its thickness and size. To do welding, you need to have some skills, and, in fact, the machine itself. You can buy it, you can hire a welder to carry out necessary work, or you can make the unit yourself.
Standard diagram of a welding machine and its types
Before you start creating a welding machine at home, you should understand its structure.
The main element of the welder that it consists of is a transformer that powers the arc of the device, controls alternating voltage and controls the quality and magnitude of the current.
The designs of standard welding machines are very diverse, but the following main types can be distinguished:
- AC apparatus;
- Working with direct current;
- Three-phase;
- Inverter.
DC welding is usually used to work with thin sheet material, automotive and roofing steel.
Welding devices of direct and alternating current are reliable, unpretentious in operation, heavy in weight and very sensitive to voltage changes. If it drops below 200 volts, it will be difficult to operate and there will be problems with ignition and maintaining the arc.
These welding machines are very similar in design, and if we have alternating current welding, then by modifying it a little, we will get a device for working with direct current.
As for inverters, thanks to the use of electronic parts, their weight has become much lighter. They are not afraid of voltage drops, but are very sensitive to overheating. You need to work with such devices carefully, otherwise they may break.
Homemade AC welding machine
A welding unit operating with alternating current is one of the most common models. It is the easiest to use and easy to assemble at home compared to other types of welders.
What is needed for this:
- Wires for secondary and primary windings;
- Winding core;
- Step-down transformer (you can take "LATRA").
What wires are needed? The optimal voltage when operating a device created independently is 60V with an optimal current of 120 -160A. Based on this, we understand that the minimum cross section copper wires to wind the primary, there should be 3-4 square meters. mm. Optimal – 7 sq. mm, which takes into account possible additional load and voltage surges.
Do not use wires with PVC or rubber insulation, as they may overheat and cause a short circuit.
If there is no wire of the required cross-section, you can use thin wires wound together. True, the thickness of the winding will increase, which will entail an increase in the dimensions of the device itself. To make a secondary winding, you can take a thick copper wire, consisting of many veins.
The homemade core is made from a transformer steel plate, the thickness of which should be from 0.35 mm to 0.55 mm. They must be folded so that a core of the required thickness is obtained, and then the device must be secured with bolts at the corners. At the end of the work, you should use a file to process the surface of the plates and make insulation.
Then the winding begins. First, the primary one (about 240 turns can be made). In order to be able to regulate the passing current, you need to make several taps with an approximate step of 20-25 turns.
How much copper is needed for the secondary winding? Typically the number of turns is 65-70. Wire cross-section – 30 – 35 sq mm. As with the primary winding, taps must be made to regulate the current. The insulation of the wires must be reliable and resistant to heat.
Winding is done in one direction and each layer is insulated. The ends of the winding are bolted to the plate and we can assume that homemade welder ready.
If you need to increase the current, a voltage boost can help in this matter, or you can do it manually by reducing the number of turns of the primary winding and switching the wire to a contact with a smaller number of turns.
When creating a welding machine, you must remember to ground it, in accordance with safety regulations. You should also always ensure that the welding machine does not overheat!
Simple DC Welding Machine
To weld cast iron and stainless steel, you will need a machine with direct current. You can create it in 15 minutes if you already have a device on alternating current. In this case, an existing device will be upgraded.
Remaking the alternator will consist of connecting a rectifier, which is assembled using diodes, to the secondary winding. The diodes, in turn, must withstand a current of 200 A and be well cooled.
The rectifier will do its job better if you use 50V capacitors and a special inductor to regulate the current.
What you need to know when connecting the device to the network permanently:
- It is imperative to use a switch, which can disconnect the device from the network at any time;
- The cross-section of the wire for connection must be greater than or equal to 1.5 square meters. mm, and the current consumption in the primary winding is a maximum of 25 A.
The way a welder works is such that he needs to be given a rest from time to time. And it doesn’t matter whether it’s a semi-automatic or a handbrake. However, if the device operates on electrodes with a diameter of less than 3 mm, then there is no need to interrupt.
Inverter: how to make a welding machine with your own hands
You can assemble an inverter yourself from small parts and wiring from a Soviet TV or vacuum cleaner.
Features of the inverter:
- The device operates with direct current and its smooth adjustment from 40 to 130 A;
- The highest current for the primary winding is 20A, the electrodes used should be no more than 3 mm;
- The electric holder must have a button, pressing which will supply voltage to the device.
All inverter elements are located on a special printed circuit board, and for better heat removal from the diodes, they are fixed to a special heat sink, which is screwed to the board. The board itself is usually made of fiberglass, approximately 1.5 mm thick.
For additional cooling of the circuit, you can use a fan fixed directly to the case in which the inverter is located.
With the help of such a device, you can safely weld non-ferrous and ferrous metals and thin sheet workpieces.
Three-phase welding machines are usually used for welding in industrial settings, so it makes no sense to make them at home.
Particularly popular are welders from Timval, Budyonny and thyristors.
Tips on how to make a welding machine at home: spot welding
One of the most convenient and economical mini weldings has recently become spot welding, which occurs by contact method. In everyday life, such a thing is used for repairing household appliances and welding batteries.
Heating occurs using a pulse, and the pulse moment does not exceed one tenth of a second, that is, everything happens very quickly.
This type of mini-welding is created using a transformer from an old microwave, which will be modified during the creation of the device. The goal is the ability to obtain a short-term pulse at the output of at least 1000A.
The modification goes like this:
- Everything is removed from the transformer except the core and primary winding;
- A wire with a cross-section of at least 100 square meters is wound in place of the secondary winding. mm;
- The main thing here is to wrap the wire very tightly around the core.
As a result, the output should be about 5 volts, but if the power is too low, you can use another transformer. Then you need to check the voltage again. If it is no more than 2000 A, the microwelding machine is ready for use.
Equipment for welding work does not have to be purchased in a store. It can be made in a home workshop. After all, in fact, the design of the simplest device is elementary and it is not difficult to assemble it with your own hands. To do this, you only need some components and a little knowledge of electrical engineering.
How to make simple and, at the same time, functional devices for welding work and what is required for this - more on this later in our article.
To assemble a simple welding machine, you need to understand the principle of its operation.
All welding work is based on transformation electric current from the network. For domestic use, we have access to electricity with a voltage of 220 volts and a current of 16-32 amperes.
As we know, this is not enough for welding.
The welding arc requires power, and this is provided by current, measured in amperes ( in simple language, this is the number of electrons supplied to the electrode). The more charge, the more productive the device will be.
To increase power, transformers are used that lower the voltage several times, but increase the flow of electrons, which allows the use of such current to form a welding arc.
A transformer is the main element that allows you to assemble the simplest apparatus, operating on alternating current.
The basis of the transformer is a magnetic core (core made of transformer steel), on which windings are wound: the primary, made of thinner wire and a large number of turns. and a secondary one, consisting of a thick cable with the least number of windings.
Magnetic cores for assembling welding machines can be used, for example, from old power transformers.
Power is provided from a household outlet and applied to the primary winding.
The windings should not be in contact with each other. Even if the transformer has windings one on top of the other, there must be a layer of insulation between them! Current from one winding to another is transmitted through the core by magnetic flux.
For full operation, it is advisable to install cooling for such a device. Computer fans can be used. Otherwise, you will need to constantly monitor the heating of the transformer and other elements, as well as take breaks in operation to cool down.
The work is carried out as follows. The workpiece is clamped between the electrodes and the current is turned on. Having set the point, the power is turned off and the part is moved.
This DIY microwave welding will ensure welding of very thin structures. The power can be increased by connecting two transformers. But it is important to assemble such an assembly correctly, otherwise a short circuit is inevitable.
DC welding
Homemade transformer machines operate on alternating current, so you can weld various grades of steel. But some metals require direct current to obtain a quality connection.
To assemble such a device, you will need to add a rectifier and chokes to the transformer to smooth the current.
Rectifiers are assembled from diodes that can withstand high power (up to 200 Amperes). They are usually large and, moreover, will require the assembly of a cooling system. Diodes are mounted in parallel to increase the current.
Such a rectifier bridge will allow you to level the electric arc and obtain higher quality seams when welding stainless steel or aluminum.
Is all this necessary?
Today you can find many schemes and designs on the Internet. various equipment for welding. From the simplest massive transformer apparatus to the most complex homemade inverters. How advisable is it to collect them and use them in a home workshop?
Just ten years ago, inverters were practically inaccessible to the general public and that’s all welding work carried out using large transformers, most often homemade ones. Their functions allow you to cook various designs using steel parts. And many experienced welders weld non-ferrous metals or cast iron with such devices. Moreover, today the situation with electrodes has greatly improved, which can be selected for almost any material.
However, transformers without a rectifier operate only on alternating current and this makes it difficult to work with stainless steel or, for example, aluminum. The use of additional rectifiers increases the size of the equipment and restricts mobility. And if this is not a problem for the workshop, then work at height becomes more difficult. But the main problem transformer welding homemade- this is the accuracy of setting modes. Factory-made inverters benefit greatly in this case.
Various spot welding designs also make working with thin-walled metals and products that can be quickly repaired much easier. But creating a truly powerful device will require more components, and they are not always available (try now looking for two identical microwave transformers).
Assembling an inverter in a home workshop will be advisable if you have almost everything necessary elements: transformers, rectifiers, transistors and others. Otherwise, why bother searching for and assembling a device with dubious power and configuration, if today it costs from 50-100 dollars? And for small volumes of work such a device will be more than enough?
What can you add to this material? Share your experience in assembling homemade welding equipment, especially assembly diagrams. What do you think: how effective is the use of such devices in household? Leave your comments in the discussion block for this article.
If a person plans to perform living conditions small volumes of any simple welding work, he can easily make a welding machine with his own hands, without spending money on purchasing a factory unit.
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In order to make a welding unit from readily available materials and parts, it is necessary to clearly understand the key principles of its operation and only then begin assembly. First of all, you should decide on the current power of your homemade welding machine. To connect massive reinforcement, of course, high current intensity is required, and for welding thin metal products(no more than 2 mm) – smaller.
The current indicator is directly related to which electrodes are planned to be used. Welding of sheets and structures with a thickness of 3 to 5 mm is carried out with 3–4 mm rods, and with a thickness of less than 2 mm – with 1.5–3 mm rods. If you use four-millimeter electrodes, the current strength homemade installation should be 150–200 A, three-millimeter – 80–140 A, two-millimeter – 50–70 A. But for very thin parts (up to 1.5 mm), a current of 40 A is quite sufficient.
The formation of an arc for welding from mains voltage in any welding machine is achieved through the use of a transformer. This device includes in its design:
- windings (primary and secondary);
- magnetic circuit
It's easy to make a transformer yourself. The magnetic core, for example, is assembled from transformer steel plates or other material. The secondary winding is necessary directly for welding work, and the primary winding is connected to a 220-volt electrical network. Professional units necessarily have in their design some additional devices that improve and enhance the quality of the arc and allow you to smoothly adjust the current intensity.
Homemade welding machines, as a rule, are made without additional accessories. The power of the transformer is selected based on the current strength. To obtain the calculated power, you need to multiply the current used for welding by 25. The resulting product, when multiplied by 0.015, gives us the required diameter of the magnetic core. And to calculate the required winding cross-section (primary), the power should be divided by two thousand and multiplied by 1.13.
Determining the cross-section of the secondary winding will have to “suffer” a little longer. Its value depends on the density of the welding current used. With a current strength of around 200 A, the density is 6A/square millimeter, from 110 to 150 A - 8, less than 100 A - 10. To set the required cross-section of the secondary winding you need:
- divide the welding current by its density;
- multiply the resulting value by 1.13.
The number of turns of wiring can be determined by dividing the cross-sectional area of the magnetic circuit by 50. Another important point, which those who plan to know need to know self-production welding machine, is that the welding process can be “soft” or “hard” depending on the voltage available at the output terminals (at their clamps) of the unit.
The specified voltage sets the features external characteristics current for welding, which can be gently or steeply falling, as well as increasing. In self-assembled welders, experts advise using current sources that are described by a flat or steeply falling characteristic. They show minimal changes in current when the electric arc oscillates, which is optimal for welding at home.
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Now that we know the main features of the welder, we can begin assembling a homemade welding machine. Now on the Internet there are many diagrams and instructions for performing such a task, which make it possible to create almost any equipment for welding - AC and DC, pulsed and inverter, automatic and semi-automatic.
We will not go into complex technical “wilds”, and will tell you how to make a welding machine of the simplest transformer type. It will operate on alternating current, providing efficient welding and quite decent seam quality. welded joint. Such a unit will allow you to perform any household work that requires welding of metal and steel products. To make it you will need the following materials:
- a couple of tens of meters of thick (preferably copper) cable (wire);
- iron for the core of a transformer device (iron must have a sufficiently high magnetic permeability).
It is most convenient to make the core using a rod, traditional U-shaped. In principle, it is also possible to use a core of a different configuration, for example, a round one from the stator of any burnt-out electric motor, but be prepared for the fact that it is much more difficult to wind windings onto a round structure. The recommended cross-sectional area of the core for a standard household welding unit, made independently, is about 50 square centimeters.
This area is enough for the installation to use rods with a diameter of 3–4 millimeters.
There is no point in making a larger cross-section, since the unit will become much heavier, but you will not achieve a real technical effect. If you are not satisfied with the recommended cross-sectional area, you can calculate its value yourself using the diagram given in the first part of our article.
The primary winding must be made of copper wire with high performance thermal resistance (during welding the winding is exposed to high temperatures). This wire, in addition, must have cotton or fiberglass insulation. As a last resort, it is allowed to use a wire in a rubber-fabric or ordinary rubber insulating sheath, but in no case in a polyvinyl chloride sheath.
By the way, you can make the insulation yourself by cutting two-centimeter wide strips of cotton or fiberglass. With these strips you wrap copper cable, after which you impregnate the wire with homemade insulation with any electrical varnish. Believe me, such insulation will not overheat when using 6-7 welding rods (when they are burned during the average duration of welding work).
The cross-sectional areas of the windings are calculated according to the principles that were outlined earlier. It seems that you will not have any problems with these calculations. Typically, the cross-sectional area of the “secondary” wire is taken at the level of 25–30 square millimeters, the “primary” – 5–7 (values for homemade units, which will work with rods with a diameter of 3–4 millimeters).
It is also easy to determine the length of a piece of copper wire and the number of turns for both windings. And then they begin to wind the coils. Their frame is made according to geometric parameters magnetic circuit. The dimensions are selected in such a way that the magnetic circuit fits onto the core, made of textolite or cardboard used in electrical engineering, without any difficulty.
The winding of the coils has a small peculiarity. The primary winding is wound in half, then half of the secondary is placed on it. After this, the second part of the coil is processed in a similar way. To improve the insulating properties, it is advisable to lay pieces of cardboard strips, fiberglass or thick paper between the layers.
After assembling a do-it-yourself welding installation, it must be adjusted. To do this, you need to plug it into the network and measure the voltage on the secondary winding. Its value should be 60–65 V. If the voltage is different, you will need to wind (or wind) part of the winding. Such procedures will have to be performed until the specified voltage value is reached.
The primary winding of the assembled transformer is connected to an internal laying cable (IRP) or to a two-core hose wire (SHRPS), which will be connected to a 220 volt network. The secondary winding (its leads) is connected to insulated PRG wires, one of them is then in contact with the product being welded, and the welding rod holder is attached to the second. The homemade welding unit is ready!
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In his practice, any radio amateur often needs to strongly heat or carefully weld one or another part. There is no point in using a conventional welding unit for these purposes, since even without it you can form a high-temperature flow quite simply and without expense.
If you have an old autotransformer lying around, which was previously used to regulate the supply voltage of Soviet lamp-based televisions, it is easy to adapt it to create a voltaic arc. To do this, you need to connect graphite electrodes between its terminals. Such a simple design will make it possible to perform simple welding work, for example, the following:
- repair or production of thermocouples: a welder from an autotransformer allows you to repair thermocouples in which the so-called “ball” breaks, and other equipment for similar repair work simply does not exist;
- connecting the power buses to the filament element of a conventional magnetron;
- welding of any wires and cables;
- heating structures made of springs and similar parts to high temperatures;
- hardening of all kinds of devices made from (they are heated with an arc and then immersed in machine oil).
If you decide to make a welder based on an autotransformer, you need to handle it extremely carefully, since it does not have galvanic isolation from the electrical network. This means that misuse homemade device may result in electric shock.
To perform all the above “minor” work, it is recommended to use an automatic transformer with a voltage (output) of 40–50 volts with low power (about 200–300 watts). Such a device is capable of delivering 10–12 amperes of operating current, which is quite enough for welding wires, thermocouples and other elements. The electrodes for the described mini-welding machine are ordinary pencil leads.
It is better if they are soft, however, medium and hard pencils are also suitable. Holders for such graphite rods can be made from old terminal blocks found on any electrical devices. The holder is connected to the winding (as you understand, secondary) of the autotransformer through one of the existing terminals, and the product that needs to be welded is also connected to it, but through a different terminal.
The handle of the electrode holder can be easily made from an ordinary fiberglass washer or from another heat-resistant element. Finally, let’s say that the arc on a welding machine from an autotransformer does not burn for very long. On the one hand, this is bad, on the other hand, it is very good, since the short duration of its operation eliminates the risk of overheating of the transformer device.
It is difficult to do without a welding machine in construction, installation and repair. Typically, equipment is purchased from finished form. However, you can go another way: make a welding machine yourself, because a self-made device will significantly save money and will become a fun activity for those who love to tinker.
About connection methods, windings and electrodes
Exist different kinds welding machines. The most common mistake made by novice craftsmen is the desire to immediately make a complex device. Schemes for the production of a welding machine can be easily found on the Internet; it is best to give preference to the type of equipment the production of which will not cause significant difficulties and will not take much time. Repairing your own welding machine will not bring big problems and significant financial expenses for the person who manufactured the equipment.
A logical question immediately arises: which welding machine? would be better suited for working at home? Small size only. The optimal solution The problem will be creating a device from devices already at the disposal of the craftsman. For work you will need a three-phase transformer. The primary ones need to be connected. In a welding machine, this is done on the magnetic circuit with a “triangle”. This method is used only for a device that is planned to be connected to a three-phase network with a voltage of 380/220 V.
Power supply and the specific design of the device are the tasks that need to be addressed first. If food and internal organization equipment do not correspond to each other, this will lead to the fact that the equipment, the creation of which took time and effort, will pose a danger to human life and health. If the welding machine will be powered from single-phase network 220 V, the connection of the primary winding of the transformer must be made differently. The extreme rods of the device's magnetic cores are connected in an anti-parallel manner. For such a welding machine, a different principle of fastening the secondary windings is used: a fixed circuit.
If the device is powered from a single-phase 220 V network, it also differs in the features of the additional winding. It is wound onto all the windings of the electrical wire that the welding machine has. What is it for? During welding, step changes in the welding current occur. They need ballast, whose role is played by the additional winding. Her distinguishing feature: 40-50 turns. For a small-sized welding machine, two-stage regulation of electrical power is most suitable.
Beginners often choose the wrong electrode size for the device.
In order to make a DC welding machine yourself, you need a high-power power source that is capable of converting the rated voltage of a conventional single-phase network and providing a constant value of the corresponding current. This is necessary in order for a normal electric arc to arise and be maintained.
A high-power power supply will require the following components:
- Rectifier.
- Inverters.
- Current and voltage transformer.
- Current and voltage regulators (to improve quality characteristics the electric arc itself).
- Assistive devices.
There is a simple rule that will help you do right choice: The stronger the electrical network and the thicker the electrical wiring, the larger the electrode should be.
Main components of the welding machine:
- Transformer magnetic circuit.
- Primary windings.
- Secondary windings.
- Additional winding.
- Remote capacitors.
- Welding mode switch.
- Contact temperature sensor and alarm sound device.
- Welding mode switches.
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Why is concrete needed?
The body of the welding machine is an important issue. For the manufacture of cases similar equipment It is customary to use specially prepared concrete. He must have good indicator plasticity. The one that most easily takes the desired shape and hardens in the shortest possible time is suitable.
The hull will require fine sand and cement. The first should be 75% of the dry concrete mixture, the second should be a fifth of it. The remaining 5% of the dry mixture is PVA glue and glass wool in a 1:1 ratio. Instead of glue, you can use water-soluble latex.
Many novice craftsmen believe that making a welding machine is much easier than making its body. In fact, there is nothing difficult if you perform all the actions sequentially. The main mistake is the incorrectly selected body thickness; it should not be less than 1 cm. The welding machine must be cleaned. Then the device is dried and only then the manufacture of the case begins. When the concrete has hardened, the welding machine must be processed on the outside. This requires an organic monomer.
Styrene or methyl methacrylate are suitable for this task. Once the concrete is saturated with monomer, it is necessary to heat treat the surface. The temperature for these purposes must be at least 70 0 C. In this case, polymerization of the monomer occurs. As a result of this procedure, a waterproof layer is formed on the body of the device itself. After it, the welding machine will be protected from the influence of the external environment.
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The easiest way
Spot welding is most in demand in everyday life, but often a person simply does not have time to manufacture the complex internal part of a welding machine. If it causes difficulties, you can resort to the most primitive solution to the issue. Check which one is faulty Appliances is in the house.
If a microwave oven breaks down, do not rush to throw it away - if you have new electrical wiring, pieces of wood, clamps and tips - the device will spot welding can be produced very quickly.
You will need:
- Washers.
- Self-tapping screws.
- Staples.
They must correspond to the intended dimensions of the welding machine. If the transformer of a broken microwave oven is working, it will become the basis of new homemade equipment.
A welding machine is used in some types of body work to connect metal parts. However, work using these devices is usually carried out in the presence of serious damage to the body, which is relatively rare. Therefore, purchasing a new, relatively expensive device for one-time use is not advisable. For household use You can make a welding machine with your own hands.
Peculiarities
It should be borne in mind that making a welding machine yourself is profitable only if you have some initial components. This is explained by the fact that, although collect the simplest model The device in question is simple, the materials required for this are very expensive. Therefore, if you purchase them separately specifically for making this device yourself, in terms of the final cost it may be close to a new branded tool, which, of course, will surpass the technical characteristics of a homemade welding machine.
Design
The basis of the instrument in question is a transformer, which serves as a source of energy. It consists of two coils of copper wire wound around a metal core. Moreover, the coils differ in the number of turns. The one that is connected to the electrical network is called primary. In this case, a current of lower voltage but higher amperage arises in the secondary coil due to induction.
It must be taken into account that a welding machine with a low current produces low-quality welding, while an excessively high current leads to burning of the electrodes and cutting of the metal.
The welding machine can be equipped with a transformer, for example, from a microwave oven. However, since a voltage of about 2000 volts appears on its secondary winding, it is necessary to make some changes to the design with your own hands in order to lower the voltage, namely, reduce the number of turns.
To reduce the voltage, the secondary winding is sawed in two places and pulled out of the coil. In this case, care must be taken not to damage the primary winding. Then the secondary winding is rewound with a thicker wire or PEV wire with enamel insulation or thermal paper 0.05 mm thick. It is advisable to use the third option, as this avoids the skin effect that occurs when using conventional wire. It consists of displacing high-frequency currents, which leads to overheating of the conductor.
The created winding is coated with thin-insulating varnish. Parameters such as the number of turns and thickness are calculated for each transformer model. However, they also optimal values: winding thickness - 0.3 mm, width - 40 mm, wire thickness - 0.5-0.7 mm.
If you don’t have a transformer from a microwave oven or any other device, you can assemble it yourself. This will require a core with cross section 25-55 cm² of transformer iron, characterized by high magnetic permeability, copper wire several tens of meters long, insulating materials.
As for the wire, the best option is considered to be heat-resistant copper wire with fiberglass, cotton or, in extreme cases, rubber insulation. You can do the insulation yourself. To do this you need to cut insulating material strips of 2 cm and wrap them around the wire.
The final stage is impregnation with electrical varnish. The better the insulation, the lower the possibility of the instrument overheating. Winding parameters are calculated based on technical characteristics device. The no-load output voltage of a homemade welding machine ranges from 60 to 65 V, the operating voltage is from 18 to 24 V. At the most high power and an electrode with a diameter of 4 mm, the power in the secondary winding is 3.5-4 kW, in the primary - about 5 kW, taking into account losses. The current is about 25 A.
The number of turns is determined based on the voltage, taking into account the cross-sectional area of the magnetic core of 2 cm. For 1 V with a high-quality wire there are 0.9 - 1.1 turns. The total is obtained by dividing the voltage level by the frequency. In this way, indicators are calculated for both windings. Based on this, you can determine the required wire length by multiplying the length of one turn by their total number. In this case, you need to take some reserve.
Before winding the coils, you need to make frames from PCB or electrical cardboard, which are loosely placed on the core. Between the primary and secondary windings it is necessary to lay insulation in the form of fiberglass, electrical or ordinary cardboard.
Frame
The welding machine should be equipped with a housing in which the transformer is placed to protect it from external factors. When choosing or manufacturing it, you need to take into account that due to electromagnetic radiation Not all materials are suitable for this. The best options consider a solid curved rigid steel case or a case made of dielectric materials. The second option is more difficult to find or assemble with your own hands, and it is also less durable, but it avoids vibration and energy loss in structural elements transformers caused by eddy currents, which are excited by strong magnetic stray fields near the windings.
In cases made of other materials, these negative phenomena can be somewhat reduced (by 30-50% depending on the design and material of the case) if longitudinal cuts are made on the case.
Most homemade welding tools do not have a solid body. This avoids problems associated with it such as vibrations, eddy currents and energy loss. However, in this case, the welding machine is exposed to external factors, which leads to a sharp decrease in the reliability and safety of work. In addition, it must be taken into account that the above-mentioned losses amount to several percent, which is almost imperceptible against the background of resistance in power lines and voltage fluctuations in the network.
In addition, it is advisable to equip the device with secondary voltage regulation for smooth regulation of the welding current. This will compensate for losses in long wires, which is especially important when working away from the power supply. Branded tools have step-by-step voltage regulation by switching windings. Home electric welding machine can be equipped with a voltage rectification circuit built on thyristors.
Reliability issue
A home-made welding machine, in most cases, is not as reliable as a branded analogue. Therefore, during manufacturing, some measures should be taken to increase it.
The main factor leading to premature failure of the devices in question is considered to be overheating. To reduce the possibility of its occurrence, it is first necessary to make effective insulation. This requires reliable winding wires with a current density of up to 5-7 A/sq.mm. However, this may not be enough.
To quickly cool the wire, it is necessary to ensure interaction with air. To do this, you need to make slots in the windings. After the first layer of wire and every two subsequent layers external parties insert getenaks or wooden planks of 5-10 mm.
This ensures that each layer of wire is in contact with air on one side. If the welding machine does not have fans, the slots are oriented vertically to ensure constant air circulation. In this case, cold air comes from below, warm air goes up.
More effective option Naturally, the cooling of the welding machine transformer is provided by a fan. Blowing it has almost no effect on the heating rate, but significantly speeds up cooling. However, it must be taken into account that for a transformer with closed windings, the problem of overheating will not be solved even when installing powerful fan. In this case, it can only be avoided by moderate operation.
There is another option to solve the problem of transformer overheating. It consists of immersing it in transformer oil. This liquid not only removes heat, but also serves as an additional insulator. In this case, the transformer housing must be a sealed container.
The most problematic in terms of overheating are toroidal transformers. They heat up quickly and cool down slowly. Also quite a serious problem homemade transformers vibration that occurs during operation due to the attraction of metal elements is considered to be a variable created by them magnetic field. Because of this, friction of the wires occurs, which leads to destruction of the insulation, as well as destruction and pushing through of the windings at the corners of the frame. To reduce the effects of vibration, it is necessary to make high-quality insulation. You also need to firmly secure all fixed elements.
Avoid storing and using the welding machine in high humidity. Water condensing in the cracks of the insulation acts as a conductor of current. The tool must be checked before use. If the voltage goes beyond 60 - 65 V, increase or decrease the winding.