Technical data of our semi-automatic welding machine:
Supply voltage: 220 V
Power consumption: no more than 3 kVA
Operating mode: intermittent
Operating voltage regulation: stepwise from 19 V to 26 V
Welding wire feed speed: 0-7 m/min
Wire diameter: 0.8mm
Welding current value: PV 40% - 160 A, PV 100% - 80 A
Welding current control limit: 30 A - 160 A
A total of six such devices have been made since 2003. The device shown in the photo below has been in service since 2003 in a car service center and has never been repaired.
Appearance of semi-automatic welding machine
At all
Front view
Back view
Left view
The welding wire used is standard
5kg coil of wire with a diameter of 0.8mm
Welding torch 180 A with Euro connector
was purchased at a welding equipment store.
Welder diagram and details
Due to the fact that the semi-automatic circuit was analyzed from such devices as PDG-125, PDG-160, PDG-201 and MIG-180, circuit diagram differs from a circuit board because the circuit was drawn up on the fly during the assembly process. Therefore, it is better to stick to the wiring diagram. On printed circuit board all points and details are marked (open in Sprint and hover your mouse).
Installation view
Control board
A single-phase 16A type AE circuit breaker is used as a power and protection switch. SA1 - welding mode switch type PKU-3-12-2037 for 5 positions.
Resistors R3, R4 are PEV-25, but they don’t have to be installed (I don’t have them). They are designed to quickly discharge choke capacitors.
Now for capacitor C7. Paired with a choke, it ensures combustion stabilization and arc maintenance. Its minimum capacity should be at least 20,000 microfarads, optimal 30,000 microfarads. Several types of capacitors with smaller dimensions and higher capacity were tried, for example CapXon, Misuda, but they did not prove to be reliable and burned out.
As a result, Soviet capacitors were used, which still work to this day, K50-18 at 10,000 uF x 50V, three in parallel. 
Power thyristors for 200A are taken with a good margin. You can put it at 160 A, but they will work at the limit, they will require the use good radiators and fans. The used B200s stand on a small aluminum plate.
Relay K1 type RP21 for 24V, variable resistor R10 wirewound type PPB.
When you press the SB1 button on the burner, voltage is supplied to the control circuit. Relay K1 is activated, thereby, through contacts K1-1, voltage is supplied to the electromagnetic valve EM1 for acid supply, and K1-2 - to the power supply circuit of the wire drawing motor, and K1-3 - to open the power thyristors.
Switch SA1 sets the operating voltage in the range from 19 to 26 Volts (taking into account the addition of 3 turns per arm up to 30 Volts). Resistor R10 regulates the supply of welding wire and changes the welding current from 30A to 160A.
When setting up, resistor R12 is selected in such a way that when R10 is turned to minimum speed, the engine still continues to rotate and does not stand still.
When you release the SB1 button on the torch, the relay releases, the motor stops and the thyristors close, the solenoid valve, due to the charge of capacitor C2, still remains open, supplying acid to the welding zone.
When the thyristors are closed, the arc voltage disappears, but due to the inductor and capacitors C7, the voltage is removed smoothly, preventing the welding wire from sticking in the welding zone.
Winding up a welding transformer
We take the OSM-1 transformer (1 kW), disassemble it, put the iron aside, having previously marked it. We make a new coil frame from PCB 2 mm thick (the original frame is too weak). Cheek size 147×106mm. Size of other parts: 2 pcs. 130×70mm and 2 pcs. 87x89mm. We cut out a window measuring 87x51.5 mm in the cheeks.
The coil frame is ready.
We are looking for a winding wire with a diameter of 1.8 mm, preferably in reinforced fiberglass insulation. I took such a wire from the stator coils of a diesel generator). You can also use ordinary enamel wire such as PETV, PEV, etc.
Fiberglass - in my opinion, the best insulation is obtained
We begin winding - the primary. The primary contains 164 + 15 + 15 + 15 + 15 turns. Between the layers we make insulation from thin fiberglass. Lay the wire as tightly as possible, otherwise it won’t fit, but I usually didn’t have any problems with this. I took fiberglass from the remains of the same diesel generator. That's it, the primary is ready.
We continue to wind - the secondary. We take an aluminum busbar in glass insulation measuring 2.8x4.75 mm (can be purchased from wrappers). You need about 8 m, but it is better to have a small margin. We begin to wind, laying it as tightly as possible, we wind 19 turns, then we make a loop for the M6 bolt, and again 19 turns. We make the beginnings and ends 30 cm each, for further installation.
Here small retreat, personally, for me to weld large parts at such a voltage, the current was not enough; during operation, I rewound the secondary winding, adding 3 turns per arm, in total I got 22+22.
The winding fits snugly, so if you wind it carefully, everything should work out.
If you use an enamel wire as a primary material, then you must impregnate it with varnish; I kept the coil in the varnish for 6 hours.
We assemble the transformer, plug it into an outlet and measure the no-load current of about 0.5 A, the voltage on the secondary is from 19 to 26 Volts. If everything is so, then the transformer can be put aside; we no longer need it for now.
Instead of OSM-1 for a power transformer, you can take 4 pieces of TS-270, although the dimensions are slightly different, and I only made 1 welding machine on it, so I don’t remember the data for winding, but it can be calculated.
We'll roll the throttle
We take an OSM-0.4 transformer (400W), take an enamel wire with a diameter of at least 1.5 mm (I have 1.8). We wind 2 layers with insulation between the layers, lay them tightly. Next we take an aluminum tire 2.8x4.75 mm. and wind 24 turns, making the free ends of the bus 30 cm long. We assemble the core with a gap of 1 mm (lay in pieces of PCB).The inductor can also be wound on iron from a color tube TV like TS-270. Only one coil is placed on it.
We still have one more transformer to power the control circuit (I took a ready-made one). It should produce 24 volts at a current of about 6A.
Housing and mechanics
We've sorted out the trances, let's move on to the body. The drawings do not show 20 mm flanges. We weld the corners, all iron is 1.5 mm. The base of the mechanism is made of stainless steel.
Motor M is used from a VAZ-2101 windshield wiper.
The limit switch for returning to the extreme position has been removed.
In the bobbin holder, a spring is used to create braking force, the first one that comes to hand. The braking effect is increased by compressing the spring (i.e. tightening the nut).
There are many welding technologies various materials and among them is capacitor welding. The technology has been known since the 30s of the last century and is of a variety. The connection of metals occurs during melting at short circuit points electric current due to the applied discharge energy of charged high-capacity capacitors. The process takes 1-3 milliseconds.
The basis of the device is a capacitor or a block of capacitors, which are charged by a constant voltage power source. Electrodes of capacitors after reaching required level energy during the charging process is connected to the welding points. The current flowing during the discharge between the parts being welded causes the surfaces to heat to such an extent that the metal melts and high-quality metal is formed.
Despite a number of advantages, capacitor welding has a number of limitations that do not allow its use everywhere. Among them:
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Equipment advantages
high process speed in automated production, up to 600 points per minute
accuracy of parts connection and repeatability of processes on the line
does not transmit infrared and ultraviolet radiation
equipment durability
welding different metals
low heat generation, no need for coolant
lack of such Supplies like electrodes or welding wire
Despite some disadvantages, the method of joining metals is widely used in industry and in everyday life.
Types of capacitor welding machines
There are two types of capacitor welding machines - with a discharge of energy storage devices directly on the surfaces being welded and with a discharge from the secondary winding of a transformer. The first, transformerless method, is more often used in shock-capacitor welding. The second method, transformer, is used to create a high-quality seam.
Impact-capacitor equipment welds parts when one of the electrodes hits the part. During an impact, the surface parts are pressed tightly against each other. A capacitor discharge occurs, forming a microarc that heats the surfaces to the melting point of metals. The parts are firmly connected.
In the transformer welding method, after charging, the capacitor is connected to the primary winding of the step-down transformer. A potential appears on the secondary winding that is several times smaller than the amplitude of the incoming pulse. During the discharge, the parts are welded, the capacitor is charged again and again transfers energy to the primary winding of the transformer. This allows long bursts of up to 5 discharges per second to be produced, which creates strong and precise welds.
Application specifics
Capacitor welding is an economical process, so it is convenient to use at home with a low-power single-phase network. The industry produces household welders with a power of 100-400 watts, which are intended for home use or in small private workshops. 
Capacitor welding has gained particular popularity in car body repair shops. Unlike arc welding, the condenser does not burn through or deform the thin walls of sheets of body parts. There is no need for additional straightening.
Capacitor welding is also used in radio electronics for welding products that cannot be soldered using conventional fluxes or fail due to overheating.
Capacitor welding machines are used by jewelers to make or repair jewelry.
In industry, point connection is used for:
- welding bolts, hooks, nuts, studs and other hardware to surfaces;
- connections between different metals, including non-ferrous ones;
- welding of watch parts, photo and film equipment;
- manufacturing of optical and lighting devices;
- electronic equipment assemblies
- and etc.
Capacitor welding is used to join microscopic parts that cannot be welded using the arc method.
DIY capacitor apparatus
You can make a capacitor-type welding machine yourself and use it at home. For this you will need
- 220 volt transformer with a power of 5-20 W with an output voltage of 5V;
- four rectifier diodes with a forward current of at least 300 mA (for example, D226b);
- thyristor PTL-50, modern replacement T142-80-16, KU 202 or similar;
- electrolytic capacitor 1000.0 x25 V;
- variable resistor 100 Ohm;
- a transformer with a power of at least 1000 W (suitable for microwave ovens);
- electrodes or welding gun (different designs are described on the Internet many times);
- copper wire with a cross-section of at least 35 mm2. - 1 meter.
- switches, fuses, housing at your discretion.
If the installation is carried out according to the diagram without errors and the parts are in good working order, then there will be no problems with the operation of the device.
There is only one problem - the output transformer. If you really decide to use a microwave transformer, and it can be bought cheaply on used parts markets, then be prepared that it will need to be rebuilt.
It is necessary to remove the magnetic shunts and the secondary winding and wind 2-5 thick turns of the secondary winding onto the free space copper wire. During the setup process, the number of turns may have to be changed. It is considered optimal that the output voltage should fluctuate between 2-7 volts, but this value also depends on the duration of the welding pulse and the thickness of the materials being welded. There is no need to be afraid to experiment, choosing different modes with a variable resistor and changing the number of turns. But don't try to get the machine to do what a conventional arc process can do. Boil water pipes and the fittings will not work, this device is for other purposes.
Devices for the transformerless type are not much more complicated, but they are more cumbersome. You will need a set of capacitors with a total capacity of about 100,000 microfarads. This is a decent weight and size battery. It can be replaced with a compact ionistor, but the device is not cheap. In addition, electrolytic capacitors do not last long. Therefore, portable and household capacitor spot welding machines are usually manufactured using a transformer circuit.
Modern devices are manufactured using slightly different technologies. The frequency and power of the discharge are regulated by PIC controllers; it is possible to automate processes and control via a computer or monitor interface. But physical processes welding has not changed. Having once assembled the simplest unit, you can subsequently add elements of computer control, production automation and control to it.
If this topic is close to you and you are ready to complement it or challenge it, share your opinion, tell us, post descriptions of your solutions in the comments block.
This type of welding refers to the spot method. It is convenient when you need to weld small parts to each other, or one small one. Capacitor welding is mainly used to work with non-ferrous metals.
As soon as it became possible to carry out precision welding at home, the method began to gain popularity among inexperienced welders. This situation has added relevance to the issue today. What is this process and how to do welding for home use yourself? We will try to examine this question in detail today.
The first difference that catches your eye is the welding speed and its environmental friendliness. A standard capacitor welder operates at high voltage. This allows you to save energy and get high-quality and straight seam. Its main application is in microwelding or, if necessary, welding large sections. This happens according to this principle:
- Capacitors collect the required amount of energy;
- The charge turns into heat, which is used for welding.
As mentioned earlier, this type of welding is environmentally friendly. The devices do not require liquid for cooling due to the absence of heat emissions. This advantage allows you to add time to the life of the capacitor device.
Operating principle of capacitor welding
During the spot welding process, the parts are clamped by two electrodes, which receive a short-term current. Then an arc forms between the electrodes, which heats the metal, melting it. The welding pulse comes into operation within 0.1 sec., it provides a common melt core for both parts of the workpieces being welded. When the impulse is removed, the parts continue to compress under the pressure of the load. The result is a common weld.
There are secondary windings, from which the current flows to the electrodes, and the primary winding receives the pulse that was formed during the capacitor charge. In a capacitor, charge accumulation occurs in the interval between the arrival of a pulse at two electrodes. Particularly good results come when it comes to or copper. There is a limitation on the thickness of the workpieces; it should not exceed 1.5 mm. This may be a minus, but this scheme works great when welding dissimilar materials.
Types of spot welding
There are two main types of do-it-yourself capacitor welding:
- Transformer. At which the capacitor discharges the energy charge onto the winding of the transformer equipment. In this case, the workpieces are located in the welding field, which is connected to the secondary winding.
- Transformerless.
Advantages
Like all other types, self-condenser welding has a number of positive features:
- With stable operation, it is possible to save energy;
- Reliability and practicality. The speed of operation allows spot welding to be possible with air cooling;
- Speed of work;
- The welding current is very dense;
- Accuracy. Taking into account the dose of energy consumed, a reliable seam of compact thickness is formed in the contact field. This method is widely used for fine welding of non-ferrous metals;
- Economical. Power consumption is 20 kVA maximum. This occurs through power take-off due to voltage stabilization in the network.
DIY unit assembly diagram
The primary winding is passed through a diode bridge (rectifier) and then connected to a voltage source. The thyristor sends a signal to the bridge diagonal. The thyristor is controlled by a special button to start. The capacitor is connected to the thyristor, or more precisely to its network, to the diode bridge, then it is connected to the winding (primary). To charge the capacitor, an auxiliary circuit with a diode bridge and a transformer is turned on.
A capacitor is used as a pulse source; its capacity should be 1000-2000 µF. To design the system, a transformer is made from a Sh40 type core, the required size is 7 cm. To make the primary winding, you need a wire with a diameter of 8 mm, which is wound 300 times. The secondary winding involves the use copper bus, in 10 windings. Almost any capacitors are used for the input, the only requirement is a power of 10 V, a voltage of 15.
When the work requires connecting workpieces up to 0.5 cm, it is worth applying some adjustments to the design diagram. For more convenient signal control, use the MTT4K series trigger; it includes parallel thyristors, diodes and a resistor. An additional relay will allow you to adjust the working time.
This homemade capacitor welding works using the following sequence of actions:
- Press the start button, it will start the temporary relay;
- The transformer is turned on using thyristors, then the relay is turned off;
- A resistor is used to determine the pulse duration.
How does the welding process take place?
After the capacitor welding has been assembled with our own hands, we are ready to begin work. First, you should prepare the parts by cleaning them from rust and other dirt. Before placing the workpieces between the electrodes, they are connected in the position in which they need to be welded. Then the device starts. Now you can squeeze the electrodes and wait 1-2 minutes. The charge that accumulates in the high-capacity capacitor will pass through the welded fasteners and the surface of the material. As a result, it melts. Once these steps have been completed, you can proceed to the next steps and weld the remaining parts of the metal.
Before welding work at home, it is worth preparing materials such as sandpaper, grinder, knife, screwdriver, any clamp or pliers.
Conclusion
Capacitor welding is very widely used both at home and in industrial areas; as we see, it is very convenient and easy to use, plus it has a large number of advantages. With the help of the information provided, you will be able to take your knowledge to a new level and successfully apply spot welding in practice.
Aluminum electrolytic capacitors are one of the main elements that ensure stable operation of high-frequency inverters welding machines. Reliable, high-quality capacitors for this type of application are produced by companies.
The first devices using the electric arc welding method used adjustable alternating current transformers. Transformer welding machines are the most popular and are still used today. They are reliable, easy to maintain, but have a number of disadvantages: heavy weight, high content of non-ferrous metals in the transformer windings, low degree of automation of the welding process. It is possible to overcome these disadvantages by moving to higher current frequencies and reducing the size of the output transformer. The idea of reducing the size of the transformer by moving from a power supply frequency of 50 Hz to a higher one was born back in the 40s of the 20th century. Then this was done using electromagnetic transducers-vibrators. In 1950, vacuum tubes - thyratrons - began to be used for these purposes. However, it was undesirable to use them in welding technology due to low efficiency and low reliability. The widespread introduction of semiconductor devices in the early 60s led to the active development of welding inverters, first on a thyristor basis, and then on a transistor one. Insulated gate bipolar transistors (IGBTs) developed at the beginning of the 21st century gave new impetus to the development of inverter devices. They can operate at ultrasonic frequencies, which can significantly reduce the size of the transformer and the weight of the device as a whole.
A simplified block diagram of the inverter can be represented as three blocks (Figure 1). At the input there is a transformerless rectifier with a parallel-connected capacitance, which allows you to increase the DC voltage to 300 V. The inverter unit converts DC into high-frequency alternating current. The conversion frequency reaches tens of kilohertz. The unit includes a high-frequency pulse transformer, in which the voltage decreases. This block can be manufactured in two versions - using single-cycle or push-pull pulses. In both cases, the transistor unit operates in a key mode with the ability to adjust the on-time, which allows you to regulate the load current. The output rectifier unit converts alternating current after the inverter into D.C. welding
The principle of operation of the welding inverter is the gradual conversion of the mains voltage. First, the AC mains voltage is increased and rectified in the preliminary rectification unit. A constant voltage powers a high-frequency generator using IGBT transistors in the inverter unit. The high-frequency alternating voltage is converted to a lower one using a transformer and supplied to the output rectifier unit. From the output of the rectifier, current can already be supplied to the welding electrode. The electrode current is regulated by circuitry by controlling the depth of negative feedback. With the development of microprocessor technology, the production of inverter semi-automatic machines began, capable of independently selecting the operating mode and performing such functions as “anti-sticking”, high-frequency arc excitation, arc retention and others.
Aluminum electrolytic capacitors in welding inverters
The main components of welding inverters are semiconductor components, a step-down transformer and capacitors. Today, the quality of semiconductor components is so high that if they are used correctly, no problems arise. Due to the fact that the device operates at high frequencies and fairly high currents, special attention should be paid to the stability of the device - the quality of the welding work directly depends on it. The most critical components in this context are electrolytic capacitors, the quality of which greatly affects the reliability of the device and the level of interference introduced into the electrical network.
The most common are aluminum electrolytic capacitors. They are best suited for use in the primary network IP source. Electrolytic capacitors have high capacitance, large Rated voltage, small dimensions, and capable of operating at audio frequencies. Such characteristics are among the undoubted advantages of aluminum electrolytes.
All aluminum electrolytic capacitors are composed of sequential layers of aluminum foil (the anode of the capacitor), a paper spacer, another layer of aluminum foil (the cathode of the capacitor) and another layer of paper. All this is rolled up and placed in an airtight container. Conductors are brought out from the anode and cathode layers for inclusion in the circuit. Also, the aluminum layers are additionally etched in order to increase their surface area and, accordingly, the capacitance of the capacitor. At the same time, the capacity of high-voltage capacitors increases by about 20 times, and low-voltage ones by 100. In addition, this entire structure is treated with chemicals to achieve the required parameters.
Electrolytic capacitors have a rather complex structure, which makes them difficult to manufacture and operate. The characteristics of capacitors can vary greatly under different operating modes and operating climatic conditions. With increasing frequency and temperature, the capacitance of the capacitor and ESR decreases. As the temperature decreases, the capacitance also drops, and the ESR can increase up to 100 times, which, in turn, reduces the maximum permissible ripple current of the capacitor. The reliability of pulse and input network filter capacitors, first of all, depends on their maximum permissible ripple current. Flowing ripple currents can heat up the capacitor, which causes its early failure.
In inverters, the main purposes of electrolytic capacitors are to increase the voltage in the input rectifier and smooth out possible ripples.
Significant problems in the operation of inverters are created by large currents through transistors, high requirements for the shape of control pulses, which implies the use of powerful drivers to control power switches, high requirements for the installation of power circuits, and large pulse currents. All this largely depends on the quality factor of the input filter capacitors, so for inverter welding machines you need to carefully select the parameters of electrolytic capacitors. Thus, in the preliminary rectification unit of a welding inverter, the most critical element is the filtering electrolytic capacitor installed after the diode bridge. It is recommended to install the capacitor in close proximity to the IGBT and diodes, which eliminates the influence of the inductance of the wires connecting the device to the power source on the operation of the inverter. Also, installing capacitors near consumers reduces the internal resistance to alternating current of the power supply, which prevents excitation of the amplifier stages.
Typically, the filter capacitor in full-wave converters is chosen so that the ripple of the rectified voltage does not exceed 5...10 V. It should also be taken into account that the voltage on the filter capacitors will be 1.41 times greater than at the output of the diode bridge. Thus, if after the diode bridge we get 220 V pulsating voltage, then the capacitors will already have 310 V DC voltage. Typically, the operating voltage in the network is limited to 250 V, therefore, the voltage at the filter output will be 350 V. In rare cases, the mains voltage can rise even higher, so capacitors should be selected for an operating voltage of at least 400 V. Capacitors can have additional heating due to high operating currents. The recommended upper temperature range is at least 85...105°C. Input capacitors for smoothing out rectified voltage ripples are selected with a capacity of 470...2500 µF, depending on the power of the device. With a constant gap in the resonant choke, increasing the capacitance of the input capacitor proportionally increases the power supplied to the arc.
There are capacitors on sale, for example, of 1500 and 2200 µF, but, as a rule, instead of one, a bank of capacitors is used - several components of the same capacity connected in parallel. Thanks to parallel connection, internal resistance and inductance are reduced, which improves voltage filtering. Also, at the beginning of the charge, a very large charging current flows through the capacitors, close to the short circuit current. Parallel connection allows you to reduce the current flowing through each capacitor individually, which increases the service life.
Choice of electrolytes from Hitachi, Samwha, Yageo
On the electronics market today you can find a large number of suitable capacitors from well-known and little-known manufacturers. When choosing equipment, one should not forget that with similar parameters, capacitors differ greatly in quality and reliability. The most well-proven products are from such world-famous manufacturers of high-quality aluminum capacitors as, and. Companies are actively developing new technologies for the production of capacitors, so their products have best characteristics compared to competitors' products.
Aluminum electrolytic capacitors are available in several form factors:
- for mounting on a printed circuit board;
- with reinforced snap-in pins (Snap-In);
- with bolted terminals (Screw Terminal).
Tables 1, 2 and 3 present the series of the above manufacturers that are most optimal for use in the pre-rectification unit, and their appearance shown in Figures 2, 3 and 4 respectively. The given series have a maximum service life (within the family of a particular manufacturer) and an extended temperature range.
Table 1. Electrolytic capacitors manufactured by Yageo
Table 2. Electrolytic capacitors manufactured by Samwha
Table 3. Electrolytic capacitors manufactured by Hitachi
| Name | Capacity, µF | Voltage, V | Ripple current, A | Dimensions, mm | Form factor | Service life, h/°C |
| 470…2100 | 400, 420, 450, 500 | 2,75…9,58 | 30×40, 35×35…40×110 |
Snap-In | 6000/85 | |
| 470…1500 | 400, 420, 450, 500 | 2,17…4,32 | 35×45, 40×41…40×101 |
Snap-In | 6000/105 | |
| 470…1000 | 400, 420, 450, 500 | 1,92…3,48 | 35×40, 30×50…35×80 |
Snap-In | 12000/105 | |
| 1000…12000 | 400, 450 | 4,5…29,7 | 51×75…90×236 | Screw Terminal | 12000/105 | |
| GXR | 2700…11000 | 400, 450 | 8,3…34,2 | 64×100…90×178 | Screw Terminal | 12000/105 |
As can be seen from Tables 1, 2 and 3, the product range is quite wide, and the user has the opportunity to assemble a capacitor bank, the parameters of which will fully meet the requirements of the future welding inverter. The most reliable are Hitachi capacitors with a guaranteed service life of up to 12,000 hours, while competitors have this parameter up to 10,000 hours in Samwha JY series capacitors and up to 5,000 hours in Yageo LC, NF, NH series capacitors. True, this parameter does not indicate a guaranteed failure of the capacitor after the specified line. Here we mean only the time of use at maximum load and temperature. When used in a smaller temperature range, the service life will increase accordingly. After the specified period, it is also possible to reduce the capacity by 10% and increase losses by 10...13% when operating at maximum temperature.
Those craftsmen who are interested in welding work have often thought about how to build an installation for pairing elements and parts. The homemade one described below semi-automatic welding will have the following specifications: mains voltage equal to 220 V; power consumption level not exceeding 3 kVA; works in intermittent mode; adjustable
the operating voltage is stepped and varies between 19-26 V. The welding wire is fed at a speed ranging from 0 to 7 m/min, while its diameter is 0.8 mm. Welding current level: PV 40% – 160 A, PV 100% – 80 A.
Practice shows that such a semi-automatic welding machine is capable of demonstrating excellent performance and a long service life.
Preparing elements before starting work
As a welding wire, you should use a regular one, one that has a diameter within 0.8 mm, it is sold in a 5 kg reel. It will be impossible to manufacture such a semi-automatic welding machine without a 180 A welding torch, which has a Euro connector. You can purchase it in a department specializing in the sale of welding equipment. In Fig. 1 you can see a diagram of a semi-automatic welding machine. For installation you will need a power and protection switch; you can use a single-phase AE circuit breaker (16A) for it. When the device is operating, there will be a need to switch between modes; for this you can use PKU-3-12-2037.
You can dispense with the presence of resistors. Their goal is to quickly discharge the inductor capacitors.
As for capacitor C7, in tandem with a choke it is capable of stabilizing combustion and maintaining the arc. Its smallest capacity can be 20,000 microfarads, while the most suitable level is 30,000 microfarads. If you try to introduce other types of capacitors that are not so impressive in size and have a larger capacity, then they will not prove to be sufficiently reliable, since they will burn out quite quickly. To make a semi-automatic welding machine, it is preferable to use old-type capacitors; they need to be arranged in the amount of 3 pieces in parallel.
Power thyristors for 200 A have sufficient reserve; it is permissible to install them at 160 A, however, they will operate at the limit, in the latter case there will be a need to use quite powerful fans during operation. The B200 used should be mounted on the surface of an oversized aluminum base.
Winding the transformer
When making a semi-automatic welding machine with your own hands, the process must begin with winding the OSM-1 transformer (1 kW).
It will initially have to be completely disassembled; the iron should be put aside for a while. It is necessary to make a coil frame using textolite with a thickness of 2 mm; this need arises for the reason that its frame does not have a sufficient margin of safety. The dimensions of the cheek should be 147x106 mm. You need to prepare a window in the cheeks, the dimensions of which are 87x51.5 mm. At this point we can assume that the frame is completely ready.
Now you need to find a Ø1.8 mm winding wire; it is preferable to use one that has reinforced fiberglass protection.
When making a semi-automatic welding machine with your own hands, you need to create the following number of turns on the primary winding: 164 + 15 + 15 + 15 + 15. In the gap between the layers you need to lay insulation using thin fiberglass. The wire must be wound with maximum density, otherwise it may not fit.
To prepare the secondary winding, you need to use an aluminum busbar, which has glass insulation with dimensions equal to 2.8x4.75 mm; it can be purchased from winders. You will need about 8 m, but you need to purchase the material with some reserve. Winding should begin with the formation of 19 turns, after which you need to provide a loop directed under the M6 bolt, then you need to make another 19 turns. The ends should have a length of 30 cm, which will be needed for further work.
When making a semi-automatic welding machine, you should take into account that if you may not have enough current at such a voltage to work with dimensional elements, then at the installation stage or during the further use of the device you can remake the secondary winding, adding three more turns to it per arm, in the end result this will give you 22+22.
A semi-automatic welding machine must have a winding that fits end to end, for this reason it should be wound very carefully, this will allow everything to be positioned correctly.
When using enamel wire to form the primary winding, it is then necessary to carry out treatment with varnish; the minimum time the coil is held in it is limited to 6 hours.
Now you can mount the transformer and connect it to the electrical network, which will allow you to determine the no-load current, which should be approximately 0.5 A, the voltage level on the secondary winding should be equivalent to 19-26 V. If the conditions match, you can put the transformer aside for a while and proceed to the next stage.
When making a semi-automatic welding machine with your own hands, instead of OSM-1 for a power transformer, it is permissible to use 4 units of TS-270, however, they have slightly different dimensions; if necessary, for this case, you can independently calculate the data for winding.
Choke winding
To wind the inductor, use a 400 W transformer, enamel wire Ø1.5 mm or larger. Winding must be done in 2 layers, laying insulation between the layers, and the requirement must be observed, which is the need to lay the wire as tightly as possible. Now you have to use an aluminum bus with dimensions of 2.8x4.75 mm, when winding you need to carry out 24 turns, the rest of the bus should be 30 cm. The core should be mounted with a gap of 1 mm, in parallel with this the textolite blanks will have to be laid.
At self-production For a semi-automatic welding machine, it is permissible to wind the choke on iron borrowed from an old tube TV.
You can use a ready-made transformer to power the circuit. Its output should be 24 V at 6 A.
Housing assembly
At the next stage, you can begin assembling the installation body. To do this, you can use iron, the thickness of which is 1.5 mm; the corners must be connected by welding. It is recommended to use stainless steel as the base of the mechanism.
The role of the motor can be the model that is used in the windshield wiper of a VAZ-2101 car. It is necessary to get rid of the limit switch, which works to return to the extreme position.
The bobbin holder uses a spring to obtain braking force; for this, you can use absolutely any one that is available. The braking effect will be more impressive if it is influenced by the compressed spring, for this you have to tighten the nut.
In order to make a semi-automatic machine with your own hands, you need to prepare the following materials and tools:
- enamel wire;
- wire;
- single-phase machine;
- transformer;
- welding torch;
- iron;
- textolite
Making such an installation will be a feasible task for a craftsman who has familiarized himself with the recommendations presented above in advance. This machine will be much more profitable in terms of cost compared to the model that was produced at the factory, and its quality will not be lower.