A good owner must have semi-automatic welding, especially for owners of cars and private property. With him you can always small works do it yourself. If you need to weld a part of the machine, make a greenhouse or create some kind of metal structure, then such a device will become indispensable assistant in personal business. Here the dilemma arises: buy or make yourself. If there is an inverter available, then it is easier to do it yourself. It will cost much less than buying in a retail network. True, you will need at least basic knowledge of the basics of electronics, the presence necessary tool and desire.
Creating a semiautomatic device from an inverter with your own hands
Structure
Convert the inverter into a semi-automatic welding machine for welding thin steel (low alloy and corrosion resistant) and aluminum alloys do it yourself is not difficult. It is only necessary to understand well the intricacies of the upcoming work and delve into the nuances of manufacturing. An inverter is a device used to lower the electrical voltage to the required level to power the welding arc.
The essence of the semi-automatic welding process in a protective gas environment is as follows. The electrode wire is fed at a constant speed into the arc burning zone. Shielding gas is supplied to the same area. Most often it is carbon dioxide. This ensures that a high-quality weld is obtained, which is not inferior in strength to the metal being joined, while there are no slags in the joint, since the weld pool is protected from negative impact air components (oxygen and nitrogen) with protective gas.
The kit of such a semi-automatic device should include the following elements:
- current source;
- welding process control unit;
- wire feed mechanism;
- shielding gas sleeve;
- carbon dioxide cylinder;
- torch gun:
- wire spool.
Welding post device
Principle of operation
When connecting the device to network is being transformed alternating current into permanent. This requires a special electronic module, a high-frequency transformer and rectifiers.
For high-quality welding work, it is necessary that the future device has such parameters as voltage, current and welding wire feed speed in a certain balance. This is facilitated by the use of an arc power source having a rigid current-voltage characteristic. The length of the arc is determined by a fixed voltage. The wire feed speed controls the welding current. This must be remembered in order to achieve from the device best results welding.
The easiest way is to use the circuit diagram from Sanych, who has long made such a semi-automatic device from an inverter and successfully uses it. It can be found on the Internet. Many home craftsmen not only made a semi-automatic welding machine with their own hands according to this scheme, but also improved it. Here is the original source:
Scheme of a semi-automatic welding machine from Sanych
Semiautomatic Sanych
For the manufacture of the transformer, Sanych used 4 cores from the TS-720. The primary winding was wound with copper wire Ø 1.2 mm (number of turns 180 + 25 + 25 + 25 + 25), for the secondary winding I used an 8 mm 2 bus (number of turns 35 + 35). The rectifier was assembled according to a full-wave circuit. For the switch, I chose a paired biscuit. I installed the diodes on the radiator so that they do not overheat during operation. The capacitor was placed in a device with a capacity of 30,000 microfarads. The filter inductor was made on the core from the TS-180. The power part is put into operation with the help of the TKD511-DOD contactor. The power transformer is installed TS-40, rewound to 15V. The roller of the broaching mechanism in this semi-automatic machine has a diameter of 26 mm. It has a guide groove 1 mm deep and 0.5 mm wide. The regulator circuit operates on a voltage of 6V. It is sufficient to ensure optimum welding wire feed.
How other craftsmen improved it, you can read messages on various forums devoted to this issue and delve into the nuances of manufacturing.
Inverter setting
To ensure high-quality operation of the semiautomatic device with small dimensions, it is best to use toroidal type transformers. They have the highest efficiency.
The transformer for the operation of the inverter is prepared as follows: it must be wrapped with a copper strip (40 mm wide, 30 mm thick), protected by thermal paper, of the required length. The secondary winding is made of 3 layers of sheet metal, isolated from each other. To do this, you can use fluoroplastic tape. The ends of the secondary winding at the output must be soldered. In order for such a transformer to work smoothly and at the same time not overheat, it is necessary to install a fan.
Transformer winding diagram
Work on setting up the inverter begins with a de-energization of the power unit. Rectifiers (input and output) and power switches must have heatsinks for cooling. Where the radiator is located, which heats up the most during operation, it is necessary to provide a temperature sensor (its readings during operation should not exceed 75 0 С). After these changes, the power section is connected to the control unit. When included in the email the network indicator should light up. Using an oscilloscope, you need to check the pulses. They must be rectangular.
Their repetition rate should be in the range of 40 ÷ 50 kHz, and they should have a time interval of 1.5 µs (the time is corrected by changing the input voltage). The indicator should show at least 120A. It will not be superfluous to check the device under load. This is done by including a 0.5 ohm load rheostat in the welding leads. It must withstand a current of 60A. This is checked with a voltmeter.
A correctly assembled inverter when performing welding operations makes it possible to regulate the current in a wide range: from 20 to 160A, and the choice of the operating current strength depends on the metal to be welded.
For making an inverter with my own hands you can take computer block which must be in working order. The body needs to be reinforced by adding stiffeners. An electronic part is mounted in it, made according to the Sanych scheme.
Wire feed
Most often, in such home-made semi-automatic devices, it is possible to feed a welding wire Ø 0.8; 1.0; 1.2 and 1.6 mm. The feed rate must be adjustable. The feeder together with the welding torch can be purchased from the distribution network. Upon request and availability necessary details it is quite possible to do it yourself. Savvy innovators for this use an electric motor from car wipers, 2 bearings, 2 plates and a Ø 25 mm roller. The roller is mounted on the motor shaft. Bearings are fixed on the plates. They stick to the roller. Compression is carried out using a spring. The wire, passing along special guides between the bearings and the roller, is pulled.
All components of the mechanism are installed on a plate with a thickness of at least 8-10 mm, made of textolite, while the wire should come out at the place where the connector connecting to the welding sleeve is installed. A coil with the necessary Ø and brand of wire is also installed here.
Broaching mechanism assy
A homemade burner can also be made with your own hands, using the figure below, where its components are shown clearly in disassembled form. Its purpose is to close the circuit, to provide the supply of shielding gas and welding wire.
Homemade burner device
However, those who want to make a semi-automatic device faster can buy a ready-made gun in the distribution network, along with sleeves for supplying shielding gas and welding wire.
Balloon
To supply shielding gas to the welding arc, it is best to purchase a cylinder standard type. If you use carbon dioxide as a protective gas, you can use a fire extinguisher cylinder by removing the mouthpiece from it. It must be remembered that it requires a special adapter, which is needed to install the reducer, since the thread on the cylinder does not match the thread on the fire extinguisher neck.
Semiautomatic do-it-yourself. Video
You can learn about the layout, assembly, testing of a home-made semiautomatic device from this video.
Do-it-yourself inverter welding semiautomatic device has undoubted advantages:
- cheaper than store counterparts;
- compact dimensions;
- the ability to cook thin metal even in hard-to-reach places;
- will become the pride of the person who created it with his own hands.
Any welder knows about the advantages of a semiautomatic device over manual electric welding. Due to their high prevalence and low cost, MMA inverters are in the arsenal of many craftsmen. But with MIG welding, the matter is different - these devices are more expensive. But, there is a way out - you can make a semi-automatic device from an inverter with your own hands. If you delve into this issue, the matter will not be so difficult.
There are fundamental differences between MMA and MIG welding. To operate the semiautomatic device, you need carbon dioxide (or a mixture of carbon dioxide and argon) and an electrode wire, which is supplied to the welding site through a special hose. Those. the very principle of semi-automatic welding is more complicated, but it is universal and its use is justified. What is needed for the operation of a semi-automatic device:
- wire feeder;
- burner;
- hose for wire and gas supply to the heating pad;
- current source with constant voltage.
- And to turn welding inverter into a semi-automatic, you need a tool, time and desire.
Preparation
Making a semi-automatic welding machine at home begins with work planning. There are two options for making MIG welding from an inverter:
- Completely make a semi-automatic welding machine with your own hands.
- To remake only the inverter - the feeding mechanism is ready to be purchased.
In the first case, the cost of parts for the feeder will be about 1000 rubles, excluding work, of course. If the factory semiautomatic device includes everything in one case, then the home-made one will consist of two parts:
- Welding inverter.
- Drawer with feeder and wire reel.
First, you need to decide on the case for the second part of the semiautomatic device. It is desirable that it be light and roomy. The feed mechanism must be kept clean, otherwise the wire will be jerky, in addition, periodically you need to change the spools and adjust the mechanism. Therefore, the box should be easy to close and open.
The ideal option is to use the old system unit:
- neat appearance- it doesn’t really matter, but it’s much more pleasant when the insides of the homemade product do not stick out and the semi-automatic device from the MMA inverter looks good;
- light, closed;
- the case is thin - it is easy to make the necessary cutouts;
- the gas valve and the wire feed drive operate on 12 volts. Therefore, a power supply from a computer is suitable, and it is already built into the case.
Now you need to estimate the size and location of future parts in the case. You can cut out approximate layouts from cardboard and check their relative position. After that, you can start work.
The best option for electrode wire is a coil weighing 5 kg. Its external diameter is 200 mm, internal - 50 mm. For the axis of rotation, you can use a sewer pvc pipe. Its outer diameter is 50 mm.
Burner
Homemade semi-automatic must be equipped with a burner. You can make it yourself, but it is better to buy a ready-made kit, which includes:
- Burner with a set of tips of different diameters.
- Supply hose.
- Euro connector.
A normal burner can be purchased for 2-3 thousand rubles. Moreover, the device is homemade, so you can not chase expensive brands.
What to look for when choosing a kit:
- what welding current is the torch designed for;
- length and stiffness of the hose - the main task hose, ensure a free wire feed to the torch. If it is soft, any kink will slow down the movement;
- springs near the connector and burner - they prevent the hose from breaking.
Feeder
The electrode wire must be fed continuously and evenly - then the welding will turn out to be of high quality. The feed rate must be adjustable. There are three options for how to make a device:
- Buy a fully assembled mechanism. Expensive, but fast.
- Buy feed reels only.
- Do everything with your own hands.
If the third option is chosen, you will need:
- two bearings, guide roller, tension spring;
- wire feed motor - a motor from wipers is suitable;
- metal plate for fastening the mechanism.
One pressure bearing - it must be adjustable, the second serves as a support for the roller. Manufacturing principle:
- holes are made on the plate for the motor shaft and for mounting bearings;
- the motor is fixed behind the plate;
- a guide roller is put on the shaft;
- bearings are fixed at the top and bottom;
Bearings are best placed on metal strips - one end is bolted to the main plate, and a spring with an adjusting bolt is connected to the other.
The made mechanism is placed in the body so that the rollers are located in line with the connector for the burner, i.e. so that the wire does not break. Before the rollers, you need to install a rigid tube to align the wire.
Implementation of the electrical part
For this you will need:
- two automotive relays;
- diode;
- PWM controller for the engine;
- capacitor with transistor;
- solenoid valve idle move- to supply gas to the burner. Any VAZ model will do, for example, from the eight;
- wires.
The wire and gas feed control scheme is quite simple and is implemented as follows:
- when the button on the burner is pressed, relay No. 1 and relay No. 2 are activated;
- relay No. 1 turns on the gas supply valve;
- relay No. 2 is paired with a capacitor and turns on the wire feed with a delay;
- wire pulling is done by an additional button bypassing the gas supply relay;
- to remove self-induction from solenoid valve, a diode is connected to it.
- It is necessary to provide for the connection of the burner to power cable from the inverter. To do this, next to the euro connector, you can install a quick connector and connect it to the burner.
The semi-automatic device has the following sequence of work:
- The gas supply is turned on.
- After a short delay, the wire feed is switched on.
Such a sequence is needed so that the wire immediately enters the protective environment. If you make a semi-automatic without delay, the wire will stick. To implement it, you will need a capacitor and a transistor through which the engine control relay is connected. Operating principle:
- voltage is applied to the capacitor;
- it is charging;
- current is applied to the transistor;
- the relay turns on.
The capacitance of the capacitor must be selected so that the delay is approximately 0.5 seconds - this is enough to fill the weld pool.
After assembly, the mechanism needs to be tested, and the manufacturing process can be seen on the video.
Alteration of the inverter
To make a semiautomatic device from a conventional inverter with your own hands, you will have to slightly redo its electrical part. If you connect the MMA inverter to the assembled case, you will be able to cook. But at the same time, the quality of welding will be far from the factory semiautomatic device. It's all about the CVC - current-voltage characteristics. The arc inverter produces a falling characteristic - the output voltage floats. And for the correct operation of the semiautomatic device, a rigid characteristic is required - the device maintains a constant voltage at the output.
Therefore, in order to use your inverter as a current source, you need to change its CVC (voltage characteristic). For this you will need:
- toggle switch, wires;
- variable resistor and two constant;
It is quite easy to get a hard characteristic on an inverter. To do this, you need to put a voltage divider in front of the shunt that controls the welding current. For the divider, fixed resistors are used. Now you can get the necessary millivolts, which will be proportional to the output voltage, and not the current strength. There is only one minus in such a scheme - the arc turns out to be too rigid. To mitigate it, you can use a variable resistor, which is connected to the divider and the output of the shunt.
The advantage of this approach is that the arc stiffness adjustment appears - such a setting is only in professional semi-automatic machines. A toggle switch switches the inverter between MMA and MIG modes.
Thus, converting an MMA inverter into a semiautomatic device, although not an easy task, is quite feasible. At the output, it turns out a device that is not inferior to the factory ones in terms of its characteristics. But it is also much cheaper. The cost of such an alteration is 4-5 thousand rubles.
Among beginners and professional welders, the inverter-type semi-automatic welding machine is the most popular device. For the first, it provides ease in acquiring welding skills, for the second it gives performance and a large set of additional settings.
semi-automatic welding equipment can be useful for almost any welder, but has a rather high cost. If there is a manual arc welding you can convert it into a semi-automatic inverter type.
The semi-automatic welding machine is initially designed to work with filler wire in a shielding gas environment (inert or active). Its difference from the conventional manual arc welding machine is the presence of a wire feeder, a gas cylinder, a special torch, and a gas and additive control unit.
The power supply itself in the form of an inverter is no different. If the feed mechanism is built into the inverter housing, then there is an additional wire connector.
Therefore, many owners of manual arc welding machines eventually have a desire to expand their capabilities and make a home-made semi-automatic device. It can be implemented very easily. There are several implementation options, which one to choose depends on the availability of funds, time and desire.
Multifunction devices
Some manufacturers of manual arc welding inverters, taking into account the desires of customers, have provided the required additional connectors. They help to convert the device into a semi-automatic device as quickly as possible.
Some models of inverter devices of the "Source" type on the rear panel have a key for switching the operating mode from MMA to MIG and a connector for controlling the on / off of the inverter. are usually completed with a 3 m euro hose with a burner at one end and a connector at the other.
Connector allows you to feed welding wire and shielding gas, in addition, a cable passes through it for supplying control signals to the electric motor for pulling the additive and connecting the gas.
There is a special cable for connection to the inverter apparatus. It must be connected to the connector through which the welding current from the inverter was supplied to the electric holder. Now, in a semi-automatic, it will go to the MIG torch.
The second cable powers the feeder from the inverter, if provided with the appropriate connector, or from another low-power 12V DC source.
Before work, the required gas flow rate is set on the gas cylinder, and the feed rate of the additive is set on the broach mechanism. The inverter sets the welding current, the value of which depends on the thickness of the metal being welded.
Then they start welding. As you can see, the transformation of manual arc welding into a semi-automatic does not need to be altered, it is enough to buy the missing equipment. The only drawback is that the inverter will come with a puller attachment.
Tractor
In a more complex case, the manufacture of a semiautomatic device consists in reworking the arc welding inverter and creating a broach device from improvised materials. If you had to repair the inverter apparatus, then you can safely implement the second option.
The system unit is ideal as a housing for the inverter-type semi-automatic broach device. It is quite easy to open, yet roomy and durable.
This will allow you to simply adjust the pressure of the rollers and install the wire spool. In favor of the system unit and the fact that it is easy to make holes in the right places, and there is a built-in power supply for 12 volts. It is needed to power the additive broach drive and the gas valve.
For the necessary fasteners, it is necessary to make mock-ups of built-in components from improvised materials and try them on inside the box. After making sure that the selected layouts are correct, you can start manufacturing fasteners.
You can buy a semi-automatic coil ready-made or make it yourself. It is very easy to manufacture. The diameter of the jaws should be 200 mm, and the cylinder on which the wire will be wound should have a diameter of 50 mm, so that it can be used as an axis plastic pipe with the same denomination.
The feed mechanism will require two pressure and one guide roller, spring. As a broach motor, it is possible to use an electric motor from the wipers. As a base on which the parts will be attached, you need to use a metal three-millimeter sheet.
Holes are drilled in the plate in the right places for attaching the rollers and the motor shaft of the future semiautomatic device. Since one roller is a pressure roller, an oblong-shaped hole is drilled for it.
A clamping spring will press on it from above, the force of which is regulated through a screw. The roller and bearings are mounted on one side of the plate, and the motor on the other. A feed roller is mounted on the motor shaft.
The resulting device is installed inside the system unit so that the place of alignment of the rollers and the axis of the MIG torch connector are in the same plane. This will prevent the crease of the wire when pulling. To straighten the additive during unwinding, a tube is installed in front of the rollers.
Control node
To supply gas and additives to a semi-automatic welding machine, you will need:
- 2 relays;
- diode;
- PWM regulator;
- capacitance with transistor and resistance;
- solenoid valve;
- wires.
A valve is required to allow gas to enter the welding zone. All components can be purchased at the sale of used parts.
The control schemes in an inverter-type semiautomatic device may be different, but their essence is simple and is as follows.
Pressing the button on the burner switches both relays. The first energizes the valve that opens the gas supply.
The second relay supplies power to the wire feed motor. But its inclusion occurs a little later due to the low-pass filter in the form of an RC chain formed by a capacitor and a resistor.
Sometimes it is required to pull the wire without gas supply. For this case, an additional button is provided, which provides a broach, bypassing the gas relay.
Self-induction from the valve is removed by connecting a diode. To power the burner from the MIG inverter, you need to install an additional one next to the euro connector, through which the current will flow.
When the button on the burner is turned on, the gas flow begins, after a while the additive is supplied. The delay time is regulated by the selected capacitance and resistor values. A pause in an inverter-type semi-automatic device is necessary to protect the weld pool from the effects of atmospheric air with gas.
When the button is turned on, voltage is supplied to the capacitance. Gradually, it is charged, when it reaches certain value the transistor opens, which causes the relay to turn on.
Burner
You can also make a burner for an inverter-type semi-automatic welding machine yourself, but it’s easier to purchase an inexpensive model with sufficient power welding current.
With self-production, you still need a euro connector and a supply cable if you want to get an aesthetic semi-automatic welding machine as a result. In addition to the welding current, the length and flexibility of the hose must also be considered.
Excessive softness of the hose leads to a kink and, accordingly, to the braking of the wire. A good addition is a spring or a strong rubber seal at the junction of the hose with the burner and the connector. This will not allow him to break in these places.
inverter
The manual arc welding inverter also needs to be redone. Although it can be used without alterations, the welding quality will then be lower than that of semi-automatic factory welding machines. It's all about the volt-ampere characteristics. The difference is minor, but it does matter.
To eliminate these differences, you will need a toggle switch, three resistances, one of which is variable.
To adjust the characteristic, it is necessary to install a divider in front of the shunt that controls the current. By changing the parameters of the divider, an adjustment will occur. The toggle switch is needed to switch the inverter operating mode from manual arc to MIG.
As a result of the refinement of the inverter and self-manufacturing filler wire drawing devices, semi-automatic type welding equipment with good parameters is obtained. At the same time, save money and get a lot of pleasure from the fact that you did everything yourself.
If you have to engage in professional welding, then it is better to purchase a ready-made semiautomatic device. To date, the choice of these devices is wide, and it is quite possible to choose a budget model of acceptable quality.
Most welding machines, especially homemade ones, are far from perfect. We offer a scheme for fine-tuning a home-made welding machine from "change" to "permanent" with your own hands and you can use electrodes of any type ( see fig. 1).
Rice. 1 Scheme of a welding machine with a highly efficient inductive-capacitive filter that smooths out the ripple of the rectified voltage.
Let's go through the diagram.
Choke L.
The core for it is taken from the choke of urban lighting lamps 1N400N37-110. When removing the old windings, it is necessary to save the cardboard spacers, which provided a gap between the main and closing parts of the core (Fig. 2).
When reassembling, they are installed in place. The new winding is wound on only one side rod - three layers of a copper bus with a section of 4x6 mm, evenly spaced along the entire length of the core. The beginning of the inductor winding is connected to the block of capacitors C1 ... C6, and the end of the winding is connected to the “+” terminal (Fig. 1).
Rectifier and filter capacitor unit.
Diodes U01 ... U04 type D161-320 or similar, designed for average rectified current - above 250 A and reverse voltage - at least 200 V, are mounted on standard cast radiators-coolers, which must be isolated from each other and from the body of the welding apparatus with textolite plates. Capacitors 31 ... 56 - electrolytic, type K50-3 or K50-7 two-section 250/290 (150 + 150 microfarads). The total capacitance of the block of capacitors is 1800 microfarads. It is most convenient to install them in one row on a textolite plate 4 ... 6 mm thick.
Welding current regulator R (“ballast rheostat”).
Made from one section of the limiting resistance of the bridge crane DEK-256 (Fig. 3).
This resistance is ceramic pipe with a figured spiral groove on the outer surface, in which a tire made of a material with high resistivity, with a cross section of about 20 mm2, is laid.
The choice of household welding machines on the modern market is huge - from transformer and inverter to machines plasma cutting. The main area of use of this electrical equipment for domestic purposes is the repair of auto and motorcycle equipment, welding work on small construction sites cottage construction). In this article, I propose to consider some points on the modernization of household transformer welding machines using the example of BlueWeld welding model Gamma 4.185.
Consider circuit diagram apparatus - as you can see, nothing complicated - an ordinary power transformer, with a primary winding of 220 / 400V, with thermal protection and a cooling fan.
The operating current of the device (from 25 to 160A) is regulated by means of the retractable part of the transformer core. The device is designed to work with coated electrodes from 1.5 to 4 mm in diameter. What was the prerequisite for modernization this device? First of all, the instability of the supply voltage in the area where the use of this device was planned - on other days it barely reached 170V (by the way, some inverter devices just won't start at that supply voltage). In addition, the device is not originally intended for making welds with high aesthetic characteristics (for example, when using electric arc welding in the process of artistic cold forging metal or when welding thin-walled profile pipes) - in general, the main purpose of the apparatus was to "solder" two iron blanks together. Among other things, it was very difficult to "ignite" the arc with this welding even at the rated supply voltage - there is no need to talk about low voltage at all. As a result, it was decided, first of all, to transfer the device to direct current (for stability electric arc and as a result of an increase in the quality of the welded joint) and also to increase the output voltage for a more stable and easy ignition of the electrode. For these purposes, the rectifier / multiplier circuit designed by A. Trifonov was ideally suited - basic circuit diagram(a) and current-voltage characteristics (b) are shown in the figure.
A special role in this technical solution of a seemingly ordinary rectifier is played by the X1X3 jumper - inserting it, a rectifier device is obtained from a conventional diode bridge VD1-VD4 with a low-frequency filter C1C2L1, at the output of which in idle mode we have twice the voltage (compared to the operation option device without a jumper). Let's take a closer look at how the circuit works. A positive half-wave of voltage enters the semiconductor valve VD1 and, having charged the capacitor C1 to the maximum, returns to the beginning of the transformer winding. In the other half-cycle, the charge passes to the capacitor C2, and from it to the valve VD2 and then to the winding. Capacitors C1 and C2 are connected in such a way that the resulting voltage is equal to the total (twice) voltage, which is supplied through the choke to the electrode holder and thus contributes to stable ignition of the arc. Valves VD3 and VD4 with a closed jumper X2X3 and the absence of a welding arc do not participate in the operation of the circuit. The main advantage of the circuit is that when using the conventional bridge circuit, there is a sharp decrease in the rectified voltage with an increase in the load current at the moment of ignition of the arc - it is necessary to install electrolytic capacitors of huge capacity - 15000 microfarads, and all this despite the fact that at the moment the electrode touches the surfaces to be welded and instantaneous discharge of a large capacitor, a microexplosion of the plasma occurs with the destruction of the electrode coating, and this worsens the ignition. Now a little about the design details.
Semiconductor diodes D161 or V200 with standard radiators for them are applicable as diode bridge valves.
If you have 2 D161 diodes and 2 V200 diodes, you can make the bridge more compact - the diodes are made with different conductivity and the radiators can be fastened with studs directly to each other without using gaskets. As capacitors, reinsured, I used a set of non-polar capacitors MBGO (you can MBGCH, MBGP).
The capacity of each turned out to be 400 microfarads, which was quite enough for the stable operation of the device. The current inductor L1 is wound on the core from the transformer TC-270 with a wire with a cross section of 10 mm square.
We wind until the window is completely filled. When assembling, between the halves of the transformer core we lay textolite plates with a thickness of 0.5 mm. Since it was planned to use the apparatus for welding thin-walled shaped pipes, the negative terminal of the rectifier was connected to the electrode holder, and the positive one to the "crocodile" mass. The tests carried out showed the following results: stable ignition of the arc; confident maintenance of arc burning; excellent thermal conditions during long-term operation (10 electrodes in a row); good quality welds (compared to using a machine without a straightener). Conclusion - the modernization of the welding machine using the Trifonov rectifier significantly improves its performance in all respects.
