Do-it-yourself welding machine: simple instructions for creating and using the device. Do-it-yourself DC welding machine: my scheme Do-it-yourself welding machine for tinplate
The welding machine is used for some types of body work for connecting metal parts. However, work using these devices is usually carried out in the presence of serious damage to the body, which are relatively rare. Therefore, it is not advisable to purchase a new relatively expensive device for one-time use. For domestic use, you can make a welding machine with your own hands.
Peculiarities
It should be borne in mind that it is profitable to manufacture a welding machine on your own only if there are some initial components. This is because, although it is not difficult to assemble the simplest model of the device in question, the materials required for this are very expensive. Therefore, if you purchase them separately specifically for the manufacture of this device with your own hands, in terms of the final cost, it may turn out to be close to a new branded tool, which, of course, will surpass the home-made welding machine in terms of technical characteristics.
Design
The basis of the tool in question is a transformer that serves as a source of energy. It consists of two coils copper wire wound on a metal core. Moreover, the coils differ in the number of turns. The one that is connected to the mains is called the primary. In the secondary coil, a current of less voltage, but more amperage, arises due to induction.
It should be borne in mind that a welding machine with a low amperage produces low-quality welding, while an excessively high amperage leads to burning of the electrodes and cutting the metal.
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, to reduce the number of turns.
To reduce the voltage, the secondary winding is sawn 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 a PEV wire with enamel insulation or thermal paper 0.05 mm thick. It is advisable to use the third option, as this avoids the appearance of the skin effect, which manifests itself in the case of using a conventional wire. It consists in the displacement of high-frequency currents, which leads to overheating of the conductor.
The created winding is covered with thin-insulating varnish. Parameters such as number of turns and thickness are calculated for each transformer model. However, also taken out optimal values: winding thickness - 0.3 mm, width - 40 mm, wire thickness - 0.5-0.7 mm.
If there is no transformer from a microwave oven or any other device, you can assemble it yourself. This will require a core with a cross section of 25-55 cm² made of transformer iron, which is characterized by high magnetic permeability, a copper wire several tens of meters long, and insulating materials.
As for the wire, heat-resistant copper wire with fiberglass, cotton or, in extreme cases, rubber insulation is considered the best option. You can make your own insulation. To do this, cut the insulating material into strips of 2 cm and wrap the wire around them.
The final stage is impregnation with electrical varnish. The better the insulation, the lower the possibility of overheating the tool. The winding parameters are calculated based on the technical characteristics of the device. The open-circuit output voltage of a home-made welding machine ranges from 60 to 65 V, the operating voltage is from 18 to 24 V. At the highest 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 in this case is about 25 A.
The number of turns is determined on the basis of voltage, taking into account the cross-sectional area of \u200b\u200bthe core of the magnetic circuit 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, the indicators for both windings are calculated. Based on this, you can determine the required length of wire by multiplying the length of one turn by their total number. In this case, you need to take some stock.
Before winding the coils, it is necessary to make frames from textolite or electrical cardboard, which are freely put 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 a transformer is placed to protect it from impact. external factors. When choosing or manufacturing it, it must be taken into account that due to electromagnetic radiation, not all materials are suitable for this. best options consider a fully 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, besides it is less durable, but it avoids vibration and energy loss in the structural elements of transformers caused by eddy currents, which are excited by strong stray magnetic 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 one-piece body. This avoids problems associated with it, such as vibrations, eddy currents and energy losses. 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 should be taken into account that the above-mentioned losses amount to a few percent, which is almost imperceptible against the background of resistance in power lines and voltage fluctuations in the network.
In addition, it is desirable to equip the machine 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 mains. In branded tools there is a step voltage adjustment by switching the windings. A home electric welding machine can be equipped with a voltage rectification circuit built on thyristors.
A question of reliability
A do-it-yourself welding machine, in most cases, is not as reliable as a branded counterpart. Therefore, in the manufacture should take some measures to improve it.
Overheating is considered the main factor leading to premature failure of the devices in question. To reduce the possibility of its occurrence, first of all, it is 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.
For rapid cooling of 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, getenax or wooden planks of 5-10 mm are inserted from the outside.
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, from below cold air, warm goes up.
A more efficient option for providing cooling to the transformer of the welding machine, of course, is a fan. Its blowing has almost no effect on the heating rate, but significantly accelerates cooling. However, it should be borne in mind that for a transformer with closed windings, the problem of overheating will not be solved even when a powerful fan is installed. In this case, it can be avoided only by a moderate mode of operation.
There is another solution to the problem of transformer overheating. It consists in immersing it in transformer oil. This liquid not only removes heat, but also is 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, a rather serious problem of home-made transformers is the vibration that occurs during operation due to the attraction of metal elements by the variables they create. magnetic field. Because of this, friction of the wires occurs, which leads to the destruction of the insulation, as well as the destruction and punching of the windings at the corners of the frame. To reduce the effects of vibration, it is necessary to make high-quality insulation. It is also necessary to firmly fix all fixed elements.
Avoid storage and use of the welding machine in an environment high humidity. Water condensing in the cracks of the insulation is a current conductor. The tool must be checked before use. If the voltage goes beyond 60 - 65 V, increase or decrease the winding.
With this simple welding machine, you can cut thin metals, weld copper wires, engrave metal surface. Other applications can be easily found. Such a mini welding machine can be powered by 12-24 V.
The welding machine is based on a high-voltage high-frequency converter. Built on the principle of a blocking generator with a deep transformer feedback. The generator generates short-term electrical impulses that repeat at relatively large intervals. The clock frequency is in the range of 10-100 kHz.
The transformation ratio of this circuit will be 1 to 25. This means that if you apply a voltage of 20 V to the circuit, then the output should be about 500 V. This is not entirely true. Since any impulse transformer source or generator without load has powerful high-voltage impulses, reaching a voltage of 30,000 V! Therefore, if you disassemble any impulse Chinese charging, you will see a soldered resistor parallel to the output capacitor. This and the mains load, without a resistor, the output capacitor will quickly leak out due to overvoltage, or worse than that will explode.
Therefore, attention! The voltage at the output of the transformer is life-threatening!
Diagram of a mini welding machine
Required details:
- The transformer is homemade, the manufacturing procedure is described below.
- Resistors - 0.5-2 W.
- The transistor was used FP1016 but is hard to find due to its specificity. Can be replaced with a transistor 2SB1587, KT825, KT837, KT835 or KT829 with a change in the polarity of the power supply. Another transistor with a collector current of 7 A or more, a collector-emitter voltage of 150 V or more, with a high gain (composite transistor) is also suitable.
Transformer manufacturing
The transformer is wound on a piece of ferrite rod from a radio receiver.- Collector winding - 20 turns of wire 1 mm.
- Base winding - 5 turns with a reason of 0.5-1 mm.
- High-voltage winding - 500 turns with an occasion of 0.14-0.25 mm.
We collect the scheme. If everything is in order, everything should start without problems. Since the operating frequency of the generator exceeds the audio frequency, you will not hear a squeak during operation, so do not touch the transformer output with your hands.
Start the generator with a voltage of 12 volts and increase if necessary.
The arc is ignited from a distance of 1 cm, which indicates a voltage of 30 kV. The high frequency prevents the burning arc from breaking, as a result of which the arc burns very stably. When using a copper electrode in close contact with another electrode, a plasma medium (copper plasma) is formed, resulting in an increase in the temperature of arc welding-cutting.
Tests of the welding machine by cutting and welding
We cut an arc with a razor blade.
We fuse copper wires up to 1 mm thick.
A thick copper wire was used as the electrode. It is clamped in a wooden match, as dry wood is also a good insulator.
If you like this little welding machine, then you can make it and large sizes, and power. But be extremely careful.
Also, to increase power, you can assemble a generator according to a push-pull scheme, and even on field-effect transistors, as here -. In this case, the power will be decent.
Also, do not look at the bright discharges of the arc with the naked eye, use special goggles.
Watch the video of making a welding machine on a blocking generator
It is quite possible to make a welding inverter with your own hands, even without in-depth knowledge in electronics and electrical engineering, the main thing is to strictly adhere to the scheme and try to understand well how such a device works. If you make an inverter, specifications and the efficiency of which will differ little from similar parameters of serial models, you can save a decent amount.
You should not think that a home-made device will not give you the opportunity to effectively carry out welding work. Such a device, even assembled according to a simple scheme, will allow you to weld with electrodes with a diameter of 3-5 mm and an arc length of 10 mm.
Characteristics of a homemade inverter and materials for its assembly
Having assembled a welding inverter with your own hands according to a fairly simple electrical circuit, you will receive an effective device with the following technical characteristics:
- the value of the consumed voltage - 220 V;
- the strength of the current supplied to the input of the device - 32 A;
- the current generated at the output of the device is 250 A.
During operation, the diodes of such a bridge get very hot, so they must be mounted on radiators, which can be used as cooling elements from old computers. To mount the diode bridge, you must use two radiators: top part bridge through a mica gasket is attached to one radiator, the lower one through a layer of thermal paste - to the second.
The conclusions of the diodes from which the bridge is formed must be directed in the same direction as the conclusions of the transistors, with the help of which the direct current will be converted into high-frequency alternating current. The wires connecting these terminals should be no longer than 15 cm. Between the power supply and the inverter unit, which is based on transistors, there is a sheet of metal attached to the body of the device by welding.
Power block
basis power block The welding inverter is a transformer, due to which the value of the high-frequency voltage decreases, and its strength increases. In order to make a transformer for such a block, it is necessary to select two cores Ш20х208 2000 nm. Newsprint can be used to provide a gap between them.
The windings of such a transformer are not made of wire, but of a copper strip 0.25 mm thick and 40 mm wide.
Each layer is wrapped with cash register tape to provide thermal insulation, which demonstrates good wear resistance. The secondary winding of the transformer is formed from three layers of copper strips, which are isolated from each other using a fluoroplastic tape. The characteristics of the transformer windings must comply with the following parameters: 12 turns x 4 turns, 10 kv. mm x 30 sq. mm.
Many people try to make step-down transformer windings from thick copper wire, but this is not the right solution. Such a transformer operates on high-frequency currents, which are displaced to the surface of the conductor without heating it. inner part. That is why for the formation of windings the best option is a conductor with a large surface area, that is, a wide copper strip.
Plain paper can also be used as a thermal insulation material, but it is less wear-resistant than cash register tape. From elevated temperature, such a tape will darken, but its wear resistance will not suffer from this.
The transformer of the power unit will become very hot during its operation, therefore, for its forced cooling, it is necessary to use a cooler, which can be used as a device previously used in the computer system unit.
inverter unit
Even a simple welding inverter must perform its main function - to convert the direct current generated by the rectifier of such an apparatus into high-frequency alternating current. To solve this problem, power transistors are used that open and close at a high frequency.
circuit diagram inverter unit(click to enlarge)
The inverter unit of the apparatus responsible for the conversion direct current into a high-frequency variable, it is better to assemble on the basis of not one powerful transistor, but several less powerful ones. Such a constructive solution will allow to stabilize the current frequency, as well as to minimize noise effects during welding.
The electronic also contains capacitors connected in series. They are necessary to solve two main tasks:
- minimization of resonant emissions of the transformer;
- reducing losses in the transistor block that occur when it is turned off and due to the fact that the transistors open much faster than they close (at this moment, current losses may occur, accompanied by heating of the transistor block keys).
Cooling system
The power elements of the home-made welding inverter circuit become very hot during operation, which can lead to their failure. To prevent this from happening, in addition to the radiators on which the most heated blocks are mounted, it is necessary to use fans responsible for cooling.
If you have a powerful fan available, you can get by with one by directing the air flow from it to a step-down power transformer. If you are using low-power fans from older computers, you will need about six of them. At the same time, three such fans should be installed next to the power transformer, directing the air flow from them to it.
To prevent overheating of a homemade welding inverter, you should also use a temperature sensor by installing it on the hottest radiator. Such a sensor, in the event that the radiator reaches a critical temperature, will turn off the flow electric current on him.
In order for the inverter ventilation system to work effectively, properly executed air intakes must be present in its case. The grilles of such intakes, through which air flows will flow into the device, should not be blocked by anything.
Do-it-yourself inverter assembly
For a home-made inverter device, you need to choose a reliable case or make it yourself using sheet metal at least 4 mm thick. As a base on which the welding inverter transformer will be mounted, you can use a sheet of getinaks with a thickness of at least 0.5 cm. The transformer itself is mounted on such a base using brackets that you can make yourself from copper wire with a diameter of 3 mm.
To create electronic circuit boards of the device, you can use foil textolite with a thickness of 0.5–1 mm. When installing magnetic circuits that will heat up during operation, it is necessary to provide for gaps between them necessary for free air circulation.
For automatic control you will need to purchase and install a PWM controller in it, which will be responsible for stabilizing the welding current and voltage. To make it convenient for you to work with your home-made device, it is necessary to mount controls in the front of its body. These organs include a toggle switch for turning on the device, a variable resistor knob, with which it is regulated welding current, as well as cable clamps and signal LEDs.
Diagnostics of a homemade inverter and its preparation for work
Doing is half the battle. An equally important task is its preparation for work, during which the correct functioning of all elements is checked, as well as their configuration.
The first thing to do when testing a homemade welding inverter is to apply 15 V to the PWM controller and one of the cooling fans. This will allow you to simultaneously check the performance of the controller and avoid its overheating during such a test.
After the capacitors of the device are charged, a relay is connected to the electrical supply, which is responsible for closing the resistor. If voltage is applied directly to the resistor, bypassing the relay, an explosion may occur. After the relay trips, which should happen within 2-10 seconds after the voltage is applied to the PWM controller, you need to check if the resistor has closed.
When the relays of the electronic circuit work, the PWM board should form rectangular pulses to the optocouplers. This can be checked using an oscilloscope. The correct assembly of the diode bridge of the device must also be checked; for this, a voltage of 15 V is applied to it (the current strength should not exceed 100 mA).
The phases of the transformer during assembly of the device could be connected incorrectly, which can lead to incorrect operation of the inverter and the occurrence of loud noises. To prevent this from happening, the correct connection of the phases must be checked; for this, a two-beam oscilloscope is used. One beam of the device is connected to the primary winding, the second - to the secondary. The phases of the pulses, if the windings are connected correctly, should be the same.
The correctness of the manufacture and connection of the transformer is checked using an oscilloscope and connected to a diode bridge electrical appliances with different resistance. Focusing on the noise of the transformer and the readings of the oscilloscope, they conclude that it is necessary to refine the electronic circuit of a home-made inverter apparatus.
To check how much you can continuously work on a homemade inverter, you need to start testing it from 10 seconds. If the radiators of the device do not heat up during operation of this duration, you can increase the period up to 20 seconds. If such a time period did not negatively affect the state of the inverter, you can increase the duration of the welding machine up to 1 minute.
Maintenance of a homemade welding inverter
In order for the inverter device to serve for a long time, it must be properly maintained.
In the event that your inverter has stopped working, you need to open its cover and blow out the insides with a vacuum cleaner. Those places where dust remains can be thoroughly cleaned with a brush and a dry cloth.
The first thing to do when diagnosing a welding inverter is to check the voltage supply to its input. If the voltage is not supplied, you should diagnose the performance of the power supply. The problem in this situation may also be that the fuses of the welding machine have blown. Another weak link of the inverter is the temperature sensor, which, in the event of a breakdown, must not be repaired, but replaced.
When performing diagnostics, it is necessary to pay attention to the quality of the connections of the electronic components of the device. Poorly made connections can be determined visually or using a tester. If such connections are identified, they must be corrected so as not to encounter further overheating and failure of the welding inverter.
Only if you pay due attention to the maintenance of the inverter device, you can count on it to serve you. long time and will make it possible to perform welding work as efficiently and efficiently as possible.
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Before you make a welding machine, you need to have an idea of what a step-down transformer is. People with minimal knowledge in electrical engineering can do it themselves. The manufacture of such products was especially relevant in those days when this kind of equipment did not have serial production and was not available to a wide range of customers. And the need for the use and welding of metal structures for household needs has always been and remains now. Welding is the simplest and fast way for connecting metal parts.
Types of welding and types of welding machines
Welding can be of several types, there are plasma, electroslag, arc, laser, beam, ultrasonic, gas and contact, as well as many others. AT household arc welding is usually sufficient electric type. For electric arc welding, there are transformer and inverter devices. To obtain an apparatus for direct current, it is necessary to slightly change and remake the apparatus tuned to alternating current. But the advantage nevertheless remains with modern inverter models, the mass of which is much less. Such devices have current stabilization and operate at low mains voltage, but are sensitive to overheating, which requires caution.
The design of the transformer apparatus is simple and reliable. You can make an AC welding machine yourself based on transformers. Electric arc This apparatus is produced by a high voltage current, and the apparatus itself must have a large power. The transformer used for the manufacture of the welding machine must withstand long and significant loads without overheating. The most convenient model for manufacturing is the core of which has the shape of the letter “P”, since it can be easily disassembled and it is easier to wind the winding on it (Fig. 1). But if it is not possible to find a core of this type, it is acceptable to use a toroidal type core with round section, which can be found in an electric motor, in a lator or a stator. The calculation formula for it will be similar, but has several differences.
The transformer externally is a coil of enameled copper wire wound on a core. The number of coils rarely exceeds 2, the windings on them are also 2 - primary and secondary. Windings contain a different number of turns. The primary is connected to the mains and induction occurs, giving a current of less voltage, but more amperes, to the second layer of the winding. The quality will be adversely affected by a low current, too much will cut the metal being welded and burn the electrodes.
How to make a transformer welding machine yourself: materials and tools
Figure 1. Winding on the core in the form of "P".
- transformer iron;
- copper wire;
- winding;
- core;
- thermal paper;
- technical cardboard;
- fiberglass;
- electrical varnish;
- fan.
Iron for the welding machine must have a high degree of magnetic permeability. The ideal thickness of the winding is 0.3 mm; copper sheet 40 mm wide is used for it. Thermal paper is needed to wrap the entire winding in it, its thickness must be at least 0.05 mm.
If an ordinary wire is used for winding, it may happen that the surface of the conductor overheats greatly. The fan is installed inside the transformer of the welding machine for the same purpose.
In order for a household welding machine of this type to be able to cope with electrodes with a diameter of 3-4 mm, its core must have cross section from 22 to 55 cm². A larger value will not provide more power, but the apparatus will be much heavier. The transverse area of the core is calculated by the formula S=a*b. For the primary winding, a wire in insulation made of fiberglass or cotton, resistant to temperature effects, will be very good. It is this insulation that will provide the device with long-term operation without overheating; in extreme cases, rubber insulation can also be used.
The insulating layer in the presence of fiberglass or cotton fabric can be made independently. To do this, you need to cut the fabric into narrow strips of 2 cm and wrap the wire with them, and then impregnate the winding with electrical varnish.
Correct winding of coils
In order to wind the coils correctly, you first need to make a frame, which must be freely put on the core from above. Textolite or, in its absence, technical cardboard can serve as a material for manufacturing. After winding the first row, it is required to lay a layer of insulation. Fiberglass, technical cardboard, textolite can serve as materials. Then another layer of copper winding is wound, and the second coil is made in the same way.
Particular attention should be paid to the primary winding, since it is the most difficult to rewind, and meanwhile, during the welding process, the temperature often reaches 100 ° C or more. It is most convenient to work at this stage together, so that while one lays the turns, the second would pull the wire.
Safety and machine check
Before work, you need to check the device, the voltage for which should be from 60 to 65 V. For high powers, additional winding layers will be required, they are usually made on industrial models. The voltage Ucb in the process should not be higher than 18-24 V, it depends on the diameter of the electrode. It will also be necessary to increase the winding if the magnetic permeability of the transformer iron was initially calculated incorrectly. Compliance with fire safety rules during work is also required, since sparks from welding can burn for a long time and, falling on some objects, thus set them on fire.
The welding machine is designed to perform relatively a small amount work. And therefore, after using 10-15 electrodes of 3 mm in diameter, it must cool down. If 4 mm electrodes are used, the work time needs to be reduced even further. The machine heats up the most when using the cutting mode. After completion of work, the device must be disconnected from the network.
DIY inverter welding machine
The scheme of such a device contains affordable components, it will not be difficult to assemble it yourself. For this type of work, you need knowledge of electronics and considerable experience. Many used radio components can be found in old televisions. Materials and tools:
- electrode;
- trinistors;
- diodes;
- pay;
- fan;
- diode bridge.
For correct operation the inverter requires a current with the possibility of smooth regulation from 40 to 130 A. For the primary winding of the transformer, the primary current should be 20 A, and the electrode no more than 3 mm will ensure high-quality work. Welding voltage should be turned on and off with a conveniently located button. Thin sheets of parts will allow reverse polarity welding.
It is most convenient to arrange all the elements of the circuit on printed circuit board. The trinistors and diodes used in the circuit should not overheat; for this, a heat sink is mounted on the board before they are mounted, and they, in turn, are mounted on it. The board must be made of fiberglass with a thickness of at least 1.5 mm. The fan is required for better cooling of the entire circuit, it is mounted directly on the case to accommodate the inverter.
Working with an inverter is easier than performing similar operations with a transformer apparatus.
The seam is much better. This device has the ability to weld ferrous and non-ferrous metals and workpieces from thin sheets.
According to experts, making a welding machine with your own hands is not difficult.
However, to make it, you need to have a clear idea for what, for what work it will be used.
A home-made device is completed and assembled from available components and parts. As an option for craftsmen, a plasma mechanism can also be considered.
Practice shows that with an accurate selection of components, the device will serve for a long time and reliably.
It is important to circuit diagram was as simple as possible. Sometimes they even use a microwave transformer.
The device must be operated from a 220 V AC household mains.
If you choose 380 V as the operating voltage, then the circuit and design of the device will become noticeably more complicated.
Structural diagram of the welding machine
For the production of welding works, devices operating on alternating and direct current are used.
The circuit of any apparatus includes a transformer (it is possible to use a transformer from a microwave oven), a rectifier, a choke, a holder, an electrode. It is in this sequence that electric current flows through a closed circuit.
The circuit is completed when an electric arc occurs between the electrode and the metal pieces to be connected.
In order for the quality of the welded joint to be high, it is necessary to ensure stable burning of this arc.
And to set the required combustion mode, a current regulator is used.
DC machines are used for welding elements made of thin sheet metal. With this welding method, any electrodes and electrode wire without ceramic coating can be used.
The electrode holder is connected to the rectifier through a choke. This is done in order to smooth out voltage ripples.
The inductor is a coil of copper wires, which is wound on any core. The rectifier, in turn, is connected to the secondary winding of the transformer.
The transformer is connected to the household electrical network. The connection sequence is simple and clear.
AC voltage conversion is performed using a step-down transformer.
According to Ohm's law, the voltage that is induced on the secondary winding of the transformer decreases, and the current increases from 4 amperes to 40 or more.
Approximately this value is required for welding. In principle, this device can be called the simplest welding machine.
And with the help of wires, attach the electrode holder to it. But it is impossible to use the holder for practical purposes, since the circuit does not contain other necessary elements.
And most importantly - it does not have a current magnitude regulator. As well as a rectifier and other elements.
The transformer is considered the main element of the welding machine. It can be bought or adapted already used.
Many craftsmen use a transformer from a microwave oven that has served its time. Due to its dimensions and weight, the micropulse element always takes up a lot of space in the structure.
If we consider the welding unit as a whole, then we can distinguish three main blocks that it includes:
- power unit;
- rectifier block;
- inverter block.
A home-made inverter apparatus can be arranged in such a way that it has minimal dimensions and weight.
Such devices, designed for use in the household, are now sold in stores.
The advantages of the inverter apparatus over traditional units are obvious. First of all, it should be noted the compactness of the device, ease of use, reliability.
Only one component in the parameters of this device is of concern - its high cost.
The most general calculations confirm that making such an apparatus with your own hands is easier and more profitable.
The main elements, in practice, can always be found among electrical machines and devices that ended up in storerooms. Or in a landfill.
The simplest current regulator can be made from a piece of heating coil, which is used in household electric stoves. Choke - from a piece of copper wire.
Radio amateurs came up with the simplest pulse welding method according to the scheme. It is used to attach wires to a metal board.
No complicated fixtures - just a choke and a couple of wires. The current regulator is also not needed. Instead, a fusible link is included in the circuit.
One electrode is connected to the board through a choke.
As the second, a crocodile clip is used. The plug with wires is included in the socket of a household network.
The clamp with the wire is sharply applied to the board in the place where it needs to be welded. A welding arc occurs and at this moment the fuses in the electrical panel may blow.
This does not happen because the fusible link burns out faster. And the wire remains securely welded to the board.
Product package
Homemade is going to do small jobs in the household.
All elements, electronic devices, wires and metal structures must be assembled in a specific place. Where the product will be assembled.
The choke can be used from the fittings of a fluorescent lamp. The number of wires, preferably copper, of different sections, you need to stock up more.
If the throttle is ready-made If you can't find it, you'll need to make your own.
This will require a steel magnetic circuit from an old starter and several meters of copper wires with a cross section of 0.9 squares.
Power Supply
The main element of the power supply in the inverter is a transformer.
It can be converted from a laboratory autotransformer or used to remake a microwave oven transformer that has already served its time.
It is very important not to damage the primary winding when removing the transformer from the microwave oven.
The secondary winding is removed and redone. The number of turns and the diameter of the copper wires are calculated depending on the pre-selected power of the welding machine.
The spot welding method is well implemented by an apparatus made on a microwave transformer.
The rectifier is used to convert AC voltage to DC voltage. The main elements of this device are diodes.
It is switched into certain circuits, most often bridges. An alternating current is supplied to the input of such a circuit, and a direct current is removed from the output terminals.
Diodes are selected with such power to withstand the initially specified loads. For their cooling, special radiators made of aluminum alloys are used.
When marking the installation board, it is advisable to provide a place for a choke, which is designed to smooth out the pulses. The rectifier is assembled on a separate board, from getinax or textolite.
Inverter block
The inverter converts the direct current coming from the rectifier into alternating current, which has a high oscillation frequency.
The conversion is done using electronic circuits on thyristors or powerful transistors.
If a voltage of 220 volts with a frequency of 50 Hz is applied to the input terminals of the transformer, then a direct current of up to 150 amperes and a voltage of 40 volts is fixed at the output terminals of the inverter.
These current parameters allow you to weld metal parts from various alloys.
The electronic regulator allows you to select the mode corresponding to a particular operation.
Practice shows that a home-made welding machine, in terms of its characteristics, is not inferior to factory products.
Some time ago, welding mini inverters appeared in the trading network. It took years for manufacturing companies to achieve this miniaturization.
While craftsmen have long been able to make a do-it-yourself plasma welding machine.
This step was prompted by local conditions - tightness in the workshop and the significant weight of factory inverters. A plasma machine is a great way out of this situation.
And the fact that instead of copper wires the secondary winding of the transformer is made of copper sheet has also long been known.
Assembly sequence of the welding machine
When placing elements on a metal or textolite basis, a certain order must be observed. The rectifier must be located near the transformer.
The inductor is on the same board as the rectifier. The current regulator must be located on the control panel. The body of the apparatus can be made of sheet steel or aluminium.
Or adapt the chassis from an old oscilloscope and even system block computer. It is very important not to "sculpt" the elements as close to one another as possible.
It is imperative to make holes in the walls for the installation of cooling fans and a constant flow of air.
The board with thyristors and other elements is placed as far as possible from the transformer, which gets very hot during operation. Just like a rectifier.