How to make direct current from welding alternating current. How to make a semi-automatic from an inverter? How to use a welding inverter

Modern manufacturers produce a large number of welding inverters with a wide range of functions. Among them are semi-automatic devices operating in the MIG / MAG mode, which means the supply of inert or active gas and welding wire to the junction of the workpieces. Unfortunately, the cost of such units exceeds the financial capabilities of many people. Therefore, the desire to convert welding inverters into semi-automatic devices is finding more and more followers, since significant amounts can be saved. We will consider the possibility of such an alteration and the details necessary for this.

Often, the master is faced with the question of choosing between a welding inverter or a semiautomatic device, the difference between which lies in the quality of the seam and the types of metals being welded. If a conventional inverter allows welding in AC / DC mode, stick electrodes of different thicknesses, then semi-automatic welding machines connect parts. It is fed into the melting zone at a controlled speed and has different thickness, and to ensure best result, the process takes place in an inert or active gas environment (MIG / MAG).

Semi-automatic machines allow welding all kinds of metals of various thicknesses, while the size of the electrode does not change and the working area is always at the same distance from the person. The composition has an inverter, but there is also an adjustable wire feed unit and a special hose with a torch and a cylinder. This equipment can weld aluminum alloys, carbon and stainless steel, cast iron and titanium, and with a special wire - brass and galvanized metal. When assembling a semiautomatic device from an inverter, with your own hands, you will need the following factory or home-made components:

welding machine with AC / DC modes, outputting adjustable currents from 10 to 200A, with variable pulse voltage;
burner with the possibility of supplying welding wire and the corresponding gas to the place of welding;
spring-reinforced hose to ensure uninterrupted wire and gas supply;
gas cylinder with reducer and manometer;
reverse welding cable with clamp;
Control block;
Reliable, adjustable wire feed unit for various thicknesses of welding wire.

These elements can be purchased in the factory, and some of them can be made by hand. The inverter, burner and gas cylinder must be purchased from the factory, as technical requirements these nodes require a certificate of quality.

Of course, your semiautomatic device will cost much less, but it is important that home-made elements meet the safety requirements for the production of electric welding.

The device of the torch and the hose of the semi-automatic welding machine

Using a semi-automatic welding machine, we can increase the speed of work by more than two and a half or three times, since there is no need for multiple passes of the seam, its cleaning and replacement of stick electrodes. To increase productivity, it is necessary to ensure an uninterrupted supply of inert gas, voltage and wire to the weld pool. For this purpose, a device consisting of the following components is used:

a cylinder with a reducer, configured for a flow rate of 6-10 liters per minute and equipped with a gas supply hose;
eurosleeve, hose-cable 3 m long, through which current, wire and gas are supplied, as well as a control signal;
a torch with a tip, an on button and a nozzle for different wire diameters, equipped with a nozzle for inert or active gas.

It is quite difficult to create a European sleeve on your own, you need to take into account that the diameter of the wire used ranges from 0.8 to 1.6 mm, and it must pass through the welding hose without hindrance. For this purpose, the channel is equipped with a spring, using a Teflon coating, in addition, gas is supplied through the same sleeve. The control signal from the burner button also passes through the cable, and at the end they usually put a multi-pin Euro connector, through which all components are turned on and fed.

The complex design of the burner and its operation under conditions high temperatures, implies the presence of refractory nozzles with holes for different diameters of the welding wire. Gas is supplied through the burner, as well as the wire feed mechanism to the weld pool is turned on. It consists of the following elements:

handle with control button;
burner;
gas nozzle;
calibrated current-carrying tip.

It is important to ensure the reliability of electrical contacts and the tight connection of gas hoses.

Feeder design

Assembly process welding semi-automatic do-it-yourself, can occur both using the factory feeder, and its homemade version. In order to make it yourself, you need to understand what the factory product consists of, namely:

on the front panel there is an euro connector for connecting a welding sleeve;
on the back of the case - a toggle switch for turning on the power supply and connectors for connecting to an inverter and a gas supply system;
inside the case there is a power supply unit for the feeding device;
feed unit with a fixed, freely rotating wire spool;
then there is a clamping, adjustable feeder connected through a gearbox to the motor shaft;
electric motor speed control scheme, which ensures the translational movement of the welding wire at a given speed;

a solenoid that provides or shuts off the gas supply to the burner through the valve;
gas supply pipes to the solenoid and Euro connector;
power cable welding current to the wire feed unit;
scheme for matching gas supply and wire movement with a delay of 1-2 seconds, preventing burn-out or sticking of the wire when working in an aggressive oxygen environment;
cables connecting the inverter and feeder.

It is important that the feed system is mounted on an electrically insulating material, as the welding wire is live and is an electrode, and it is necessary to prevent electrical contact with the body of the equipment.

It is necessary to provide an effective adjustable pressure of the feed roller, since the wire has different section, depending on the thickness of the workpieces to be welded. It is important to ensure the ratio of all nodes involved in the translational movement of the wire in order to avoid kinks that make it difficult to feed smoothly at the required speed. The material of the gas supply hose must be heat-resistant, and the connections must be provided with reliable clamps. It will not be difficult to choose a power supply that is suitable for the parameters, which will ensure the operation of the electric motor and electronic circuits of the feeder.

Staged assembly of a semiautomatic device

When converting inverters into semiautomatic devices, it is necessary to take into account some circumstances. When buying an inverter, it is desirable that it supports MMA + MIG / MAG mode. The device will not cost much more, but when switching to the MIG mode, it will provide a stable current-voltage characteristic at the output, which will ensure smooth operation of the semiautomatic device at a current below 40 A. Otherwise, you will have to make changes to the electronic circuit of the inverter and use PWM to stabilize the voltage parameters . This can be done provided that you understand electronics and are good at handling a soldering iron.

It is important to match the reference and output voltage by installing a divider and select the component ratings to supply a signal to the controller inputs.

Further steps for assembling a semi-automatic device from a welding inverter, a feeder and a euro-sleeve with a burner are as follows:

switch the inverter to MIG mode and connect it to the feeder with a power and control cable;
connect a gas cylinder through a reducer and a pressure gauge to the feeder, and also adjust the feed to 6-10 liters per minute, depending on the composition of the gas and welding conditions;
install and secure the coil with wire in the feed unit;
using the speed control circuit, set the required welding wire feed speed and make sure that it moves freely;
connect the burner to the euro sleeve, which, in turn, is connected to the feeder;
turn on the inverter and feed equipment and make sure there is a delay between the arrival of gas and the movement of the wire in 1-2 seconds.

Proper selection of wire thickness, composition of inert or active gas, as well as correct operation of radio-electronic components, will ensure high speed and quality of welding.

In case of difficulties, it is necessary to seek the advice of specialists in order not to cause the failure of expensive equipment, as well as to avoid the risk to life.

Summing up

We examined some ways of converting welding inverters into semiautomatic devices with our own hands. This is a fairly complex task, but on closer examination, it is not particularly difficult. It is only important to ensure the reliable functioning of the elements and electrical safety. The main thing is that these efforts and temporary losses will provide very significant cost savings.

Advantages welding machines direct current before their "alternating current counterparts" are well known. This includes soft arc ignition, the ability to connect thin-walled parts, less metal spatter, and the absence of non-welding areas. There is not even an annoying (and, as it turned out, harmful to people) cod. And all because there is no main feature inherent in AC welding machines - intermittent burning of the arc when the sinusoid of the supply voltage flows through zero

Rice. 1. Graphs explaining the process of welding on alternating (a) and direct (b) current.

Moving from graphs to real designs, it should also be noted: in AC machines, to improve and facilitate welding, powerful transformers are used (the magnetic circuit is made of special electrical iron with a steeply falling characteristic) and a deliberately overestimated voltage in the secondary winding, reaching up to 80 V, although for 25-36 V is enough to support the arc burning and metal deposition in the welding zone. We have to put up with the prohibitively large mass and dimensions of the apparatus, increased power consumption. By reducing the voltage transformed into the secondary circuit to 36 V, it is possible to lighten the weight of the “welder” by 5-6 times, bring its dimensions to the size of a portable TV while improving other performance characteristics.

But how to ignite an arc with a low-voltage winding?

The solution was to introduce a diode bridge with a capacitor into the secondary circuit. As a result, the output voltage of the modernized "welder" was increased by almost 1.5 times. The opinion of experts is confirmed in practice: when the 40-volt DC barrier is exceeded, the arc easily ignites and burns steadily, allowing even thin body metal to be welded.

Rice. 2. Fundamental circuit diagram DC welding machine.

The latter, however, is easily explained. With the introduction of a large capacity into the circuit, the characteristic of the welding machine also turns out to be steeply falling (Fig. 3). The initial increased voltage created by the capacitor facilitates the ignition of the arc. And when the potential on the welding electrode drops to U2 of the transformer (working point "A"), a process of stable arc burning with metal deposition in the welding zone will occur.

Fig.3. Volt-ampere characteristic of the welding machine at direct current.

The "welder" recommended by the author can be assembled even at home, based on an industrial power transformer 220-36 / 42 V (these are usually used in systems for safe lighting and powering low-voltage factory equipment). After making sure that the primary winding, containing, as a rule, 250 turns of insulated wire with a cross section of 1.5 mm2, is intact, the secondary ones are checked. If their condition is not important, everything (with the exception of a working network winding) is deleted without regret. And in the vacated space, a new secondary winding is wound (until the “window” is filled). For the recommended 1.5 kVA transformer, this is 46 turns of a 20 mm2 copper or aluminum bus with good insulation. Moreover, a cable (or several insulated single-core wires twisted into a bundle) with a total cross section of 20 mm2 is quite suitable as a bus.

The choice of the cross section of the electrodes depending on the power of the transformer.

The rectifier bridge can be assembled from semiconductor diodes with an operating current of 120-160 A by installing them on heat sinks-radiators 100x100 mm. It is most convenient to place such a bridge in the same housing with a transformer and a capacitor, bringing to the front textolite panel a 16-ampere switch, an “On” signal light eye, as well as “plus” and “minus” terminals (Fig. 4). And to connect to the electrode holder and the "ground" use a segment of a single-core cable of the appropriate length with a copper cross section of 20-25 mm2. As for the welding electrodes themselves, their diameter depends on the power of the transformer used.

Rice. 4. Homemade welding machine for DC welding.

And further. When testing, it is recommended that, by disconnecting the device (10 minutes after welding) from the mains, check thermal regimes transformer, diode bridge and capacitor. Only after making sure that everything is in order, you can continue to work. After all, an overheated "welder" is a source of increased danger!

Of the other requirements, it is worth noting, I think, that the welding machine must be equipped with a spark-protective mask, gloves and a rubber mat. The place where they are performed welding work, equipped according to the requirements fire safety. In addition, it is necessary to ensure that there are no rags or other combustible materials nearby, and the connection of the “welder” to the network must be carried out in compliance with electrical safety rules through a powerful plug connector of the electrical panel at the entrance to the building.

V.Konovalov, Irkutsk
Mk 04 1998

A semi-automatic welding machine is a functional device that can be purchased ready-made or made from. It should be noted that the manufacture of a semi-automatic apparatus from an inverter device is not an easy task, but it can be solved if desired. Those who set themselves such a goal should study the principle of operation of a semiautomatic device well, look thematic photos and video, prepare everything necessary equipment and accessories.

What is required to convert the inverter into a semi-automatic

To remake the inverter, making it a functional semi-automatic welding machine, you must find the following equipment and additional components:

inverter machine capable of generating a welding current of 150 A;
a mechanism that will be responsible for feeding the welding wire;
the main working element is a burner;
a hose through which the welding wire will be fed;
hose for supplying shielding gas to the welding area;
a coil with welding wire (such a coil will need to be subjected to some alterations);
an electronic unit that controls the operation of your homemade semi-automatic device.

Special attention should be devoted to the alteration of the feeder, due to which the welding wire is fed into the welding zone, moving along a flexible hose. To weld turned out to be of high quality, reliable and accurate, the speed of wire feed through the flexible hose should correspond to the speed of its melting.

Since when welding using a semiautomatic device, wire from different materials and different diameters, its feed rate must be regulated. It is this function - the regulation of the welding wire feed speed - that the feed mechanism of the semiautomatic device should perform.

Internal layout Wire spool Wire feeder (view 1)
Wire feed mechanism (view 2) Attaching the welding sleeve to the feed mechanism Construction of a homemade torch

The most common wire diameters used in semi-automatic welding are 0.8; one; 1.2 and 1.6 mm. Before welding, the wire is wound on special coils, which are prefixes of semi-automatic devices, fixed on them with the help of simple structural elements. During the welding process, the wire is fed automatically, which significantly reduces the time spent on such a technological operation, simplifies it and makes it more efficient.

The main element of the electronic circuit of the semi-automatic control unit is a microcontroller, which is responsible for regulating and stabilizing the welding current. It is from this element of the electronic circuit of the semi-automatic welding machine that the operating current parameters and the possibility of their regulation depend.

How to remake an inverter transformer

In order for the inverter to be used for a homemade semiautomatic device, its transformer must be subjected to some alterations. It is not difficult to do such an alteration with your own hands, you just need to follow certain rules.

In order to bring the characteristics of the inverter transformer in line with those required for a semiautomatic device, it should be wrapped with a copper strip, on which a thermal paper winding is applied. It must be borne in mind that for these purposes it is impossible to use an ordinary thick wire, which will be very hot.

The secondary winding of the inverter transformer also needs to be redone. To do this, do the following: wind a winding consisting of three layers of tin, each of which must be insulated with a fluoroplastic tape; solder the ends of the existing winding and the hand-made winding to each other, which will increase the conductivity of the currents.

The design used to include it in a semi-automatic welding machine must necessarily provide for the presence of a fan, which is necessary for effective cooling of the device.

Setting the inverter used for semi-automatic welding

If you decide to make a semi-automatic welding machine with your own hands, using an inverter for this, you must first de-energize this equipment. To prevent such a device from overheating, its rectifiers (input and output) and power switches should be placed on radiators.

In addition, in that part of the inverter housing where the radiator is located, which heats up more, it is best to mount a temperature sensor, which will be responsible for turning off the device if it overheats.

After all the above procedures are completed, you can connect the power part of the device to its control unit and connect it to electrical network. When the mains indicator lights up, connect an oscilloscope to the outputs of the inverter. Using this device, it is necessary to find electrical impulses with a frequency of 40–50 kHz. The time between the formation of such pulses should be 1.5 μs, which is regulated by changing the voltage value supplied to the input of the device.

It is also necessary to check that the pulses reflected on the oscilloscope screen have rectangular shape, and their front was no more than 500 ns. If all checked parameters correspond to the required values, then the inverter can be connected to the electrical network. The current coming from the output of the semiautomatic device must have a strength of at least 120 A. If the current strength is less, this may mean that a voltage is supplied to the equipment wires, the value of which does not exceed 100 V. In the event of such a situation, the following must be done: test the equipment by changing the current (in this case, it is necessary to constantly monitor the voltage on the capacitor). In addition, the temperature inside the device should be constantly monitored.

After the semi-automatic has been tested, it is necessary to check it under load. To make such a check, a rheostat is connected to the welding wires, the resistance of which is at least 0.5 ohms. Such a rheostat must withstand a current of 60 A. The current supplied to the welding torch in this situation is controlled using an ammeter. If the current strength when using a load rheostat does not correspond to the required parameters, then the resistance value of this device is selected empirically.

How to use a welding inverter

After starting the semi-automatic machine that you assembled with your own hands, the inverter indicator should show a current value of 120 A. If everything is done correctly, then it will happen. However, the inverter display may show eights. The reason for this is most often insufficient voltage in the welding wires. It is better to immediately find the cause of such a malfunction and promptly eliminate it.

If everything is done correctly, then the indicator will correctly show the strength of the welding current, which is regulated using special buttons. The adjustment interval for the operating current, which is provided, is in the range of 20–160 A.

How to control the correct operation of the equipment

In order for the semi-automatic welding machine that you assembled with your own hands to serve you for a long time, it is better to constantly monitor temperature regime inverter operation. To implement such control, it is necessary to press two buttons simultaneously, after which the temperature of the hottest radiator of the inverter will be displayed on the indicator. Normal operating temperature the one whose value does not exceed 75 degrees Celsius is considered.

If given value is exceeded, then, in addition to the information displayed on the indicator, the inverter will start emitting intermittent sound signal which you should pay attention to right away. In this case (as well as in the event of a breakdown or short circuit of the temperature sensor), the electronic circuit of the device will automatically reduce the operating current to a value of 20A, and an audible signal will be emitted until the equipment returns to normal. In addition, a malfunction of DIY equipment may be indicated by an error code (Err) displayed on the inverter indicator.

A do-it-yourself semiautomatic device from an inverter can be made without much difficulty if you have the appropriate technical knowledge. To make a semiautomatic device with your own hands, you will need to prepare a certain list of mechanisms, devices, tools and materials that are part of the unit.

The semiautomatic device from the inverter includes an inverter and a welding torch.

Preparation for manufacturing and design features

Designed by home craftsmen various schemes designing semiautomatic devices from an inverter.

The most common device scheme involves the necessary list of tools and materials:

welding inverter, which has the ability to deliver a working current of about 150 A;
a feed mechanism that feeds the electrode wire into the welding zone;
burner;
flexible hose;
working bobbin with electrode wire, which has changes in the device;
device control unit.

The inverter should be about 150 A.

Particular attention should be paid to the feed mechanism. Using this structural element, the electrode wire is fed to the burner through a flexible hose. The ideal wire feed speed corresponds to the rate of wire melting. The indicator of the wire feed speed, which is provided by the feeder, has a significant impact on the process of work and the quality of the welding seam using a semi-automatic welding machine.

When designing a semiautomatic device, it is necessary to provide for the possibility of changing the speed of feeding the electrode wire into the welding zone. The ability to change the feed rate of the electrode material allows you to work with consumables of various diameters and from different materials. Most often, when operating semi-automatic welding machines, wire with dimensions of 0.8 mm, 1 mm, 1.2 mm and 1.6 mm is used. The wire is wound on special coils installed in the welding device.

If the wire feed is carried out fully automatically, this significantly reduces the time required for welding workpieces.

The semi-automatic control unit is equipped with a channel for adjusting and stabilizing the working current. Operating current parameters are controlled by the microcontroller in pulse-width mode. The voltage on the capacitor largely depends on the pulse-width parameter of the current. The voltage on the latter directly affects the strength of the working welding current.

Choosing a transformer for the inverter and assembling the unit

Before self-designing a semi-automatic device, it is required to determine the type and power of the welding transformer, which is planned to be installed in a semi-automatic device. It should be remembered that when using wire for the welding process minimum size 0.8 mm working welding current should be 160 A. The power of the welding transformer to obtain such a current should be 3 kW. When choosing a transformer, you should pay attention to the fact that the toroidal core transformer has a lower weight compared to other types of devices.

When manufacturing a transformer, several subtleties must be taken into account. The transformer must be wrapped with a copper strip with dimensions (40 mm - width and 30 mm - thickness). Before using the copper strip, it is first wrapped with thermal paper. Use for winding ordinary copper wire not possible, because it is very hot.

The secondary winding of the transformer is made of three layers of tin. The layers of tin are isolated from each other with the help of a fluoroplastic tape. At the exit, the ends are soldered together to increase conductivity. In the case where the transformer is installed, a fan is mounted for blowing in order to increase the cooling of the system components during the operation of the device.

Adjustment of the current in the device can be carried out in two ways: on the primary and secondary windings. The implementation of the adjustment in the first way requires the use of a thyristor adjustment circuit. This method of regulation has certain disadvantages, which are eliminated by including a relay and some switching elements in the circuit.

When applying current regulation in the secondary winding, a high ripple occurs, to reduce which a thyristor circuit is used. The use of switching circuits leads to an increase in the weight of the structure and the cost of the installation. For this reason, the use of primary current regulation is considered more acceptable.

To smooth out ripples, a smoothing inductor and a capacitor with a capacity of about 50,000 uF are built into the secondary winding circuit. This configuration of the device allows you to smooth out voltage ripples when choosing any current control scheme.

As a gearbox for wire feed, you can use a gearbox from a VAZ windshield wiper.

Setting up a semi-automatic inverter

When assembling a semi-automatic inverter with your own hands, it is required for power switches, input and output rectifiers to ensure good cooling by using radiators. A thermal sensor is also required in the housing. After the installation of the power part of the device, it is connected to the control unit of the device.

The finished device can be connected to the network. After the indicator lights up, an oscilloscope is connected to the device and the correct operation is checked. Bipolar pulses should have a frequency of 40-50 Hz, and the time between them is corrected by changing the input voltage. The normal time interval between pulses should be 1.5 µs.

The pulses that the oscilloscope registers must have rectangular fronts with a duration of no more than 500 ns.

After checking the inverter, it is connected to the household electrical network. When connecting the device, the indicator should show 120 A. If this indicator is not reached, it is necessary to check the correct assembly of the device.

After testing the device at idle, the device is tested under load. For this purpose, it is required to include a load in the form of a 0.5 Ohm rheostat in the welding wire circuit, which is capable of withstanding a current of more than 60 A. With this load, the current is controlled using a voltmeter.

After assembling the unit, its performance is checked. To do this, click on the start button. Immediately after this, carbon dioxide begins to flow, after a few seconds the current is turned on, the supply of the electrode wire begins. When the device is turned off, the supply of the operating current and the electrode wire is first stopped, and only after a few seconds the electrovalve is closed, which ensures the supply of carbon dioxide to the welding area. As a valve to ensure the supply of carbon dioxide, you can use the valve for supplying water to the rear window of a VAZ car.

Rules for using the welding inverter and the use of the unit

After starting the inverter, the current required for operation is set using the controller. In the case of correct settings at the output of the device, the electric current is 120 A. Using the control unit, if necessary, the current strength can be changed in the range from 20 to 160 A. When using the unit, its heating temperature should be controlled. The heating temperature should not exceed 75º C. To control it, a temperature sensor should be installed in the device. If the temperature rises above the set maximum, the device should be switched off and allowed to cool down. To improve cooling, the unit provides for the installation of several fans.

Semi-automatic welding, made on the basis of an inverter, is used to carry out the procedure for precise welding of products from various types become. In addition, the device is used for welding thin metal blanks. The use of a semi-automatic device is common during automotive repair work body.

After manufacturing semi-automatic welding from an inverter for the home, this unit becomes an indispensable device used in household for execution a large number various welding jobs.

The use of a semi-automatic welding machine makes it easier to work with metals. This technique can easily join various alloys. You can make a semi-automatic welding machine with your own hands from an existing inverter, and homemade unit will be distinguished by versatility and functionality in use, allowing you to save on the purchase of industrial equipment.

Design features

A design feature of the semi-automatic welding machine is the constant supply of melted wire to the welding zone, which is used instead of metal electrodes. Wire feeding is carried out automatically, with the possibility of changing the speed of the flexible electrodes. The used welding wire will ensure constant contact of the surfaces to be joined, such material has a lower resistance compared to standard electrodes, which improves the quality of the connection.

Semi-automatic welding is versatile, which allows using this technology to weld metals of various characteristics, including stainless steel, non-ferrous alloys, aluminum and others. master correct technique semi-automatic welding is not difficult. Homemade devices are easy to use, so they can be recommended to ordinary homeowners. Depending on their variety, semi-automatic machines may have an additional nozzle for gas supply, and the joining of metals is carried out in a protective environment, which makes it possible to exclude the subsequent formation of corrosion in the weld.

The inverters for welding offered today in stores are versatile, and many of them have an implemented two-in-one function. With low power and dimensions, a two-in-one semiautomatic device can work with refractory metals and thick metal blanks.

Many homeowners who often have to perform welding work decide to manufacture such equipment themselves. The advantages of homemade semiautomatic devices from an inverter include the following:

Among the shortcomings of this technology and the equipment itself, one can note high cost semi-automatic devices, which, with characteristics similar to those of an inverter, can have a price two to three times higher. It is not surprising that many homeowners decide to make equipment with their own hands, which can significantly reduce costs without losing the quality of the completed apparatus.

DIY manufacturing

The easiest way is to make a homemade semiautomatic device from an inverter based on a powerful power unit. You can make an inverter yourself or use it from the equipment at your disposal. For a semi-automatic device, inverters with a capacity of at least 150 amperes should be used.

There are schemes for reworking equipment that allow you to set the power that will be enough for semi-automatic welding. A device of this type will be difficult to implement, therefore, only experienced radio amateurs who can make truly complex equipment can be recommended to use low-power power units.

Craft quality equipment it is possible if you have a starting circuit of a semi-automatic welding inverter on hand. The characteristics of such a unit include the following:

Primary current - 8-12 A.
Supply voltage - 220 or 380 volts.
The open circuit voltage is 36-42 Volts.
Welding current - 40−120 amperes.
Voltage adjustment in plus or minus 20% increments.

These are the optimal parameters for a household semi-automatic welding machine that will cope with metals of various refractoriness. Subsequently, using additional drawings to increase the power of the inverter, you can change the basic characteristics, which allows the use of such equipment for domestic and industrial purposes.

Required Components

To make a semi-automatic garage welding machine with your own hands, you will need the following:

Torch prefix for the inverter.
Wire feeder.
Robust inner hose for welding wire.
Bobbin with wire.
Sealed gas hose.
Inverter control unit.

The easiest way is to place the inverter and the mechanical control unit in a separate box, for which they use blocks from an old computer. The presence of power in the system unit can significantly simplify the manufacture of equipment.

The roller mechanism for the wire can be made from a motor from a car windshield wiper. Under such a motor, a mechanism frame is designed, which is cut out of metal elements and welded or bolted together.

The burner and hose can be made independently from a gun from polyurethane foam and silicone. You can also purchase ready-made kits, which will ensure the safety of working with a semi-automatic device and simplifies its manufacture.

When making a wire feed mechanism, all the components used must be placed opposite each other, which will subsequently ensure a uniform supply of flexible electrodes. The rollers should be centered relative to the fitting in one slot, in the future this will allow you to smoothly change the wire feed speed. A diagram of the wire feed speed controller of a semi-automatic welding machine can be easily found on the Internet.

All used metal elements should be fixed on a sheet of plywood, thick plastic or textolite. Since electricity is supplied to the metal elements used, the grounding of each node should be checked. This will eliminate the possibility of short circuits, which can lead to serious damage to equipment.

Mechanics control scheme

A small electric motor and a broaching mechanism will be responsible for feeding the welding wire, the operation of which is controlled by a PWM controller. The quality of the welding performed will directly depend on the uniformity of the welding wire feed in working area. It is necessary to pay due attention to the correct manufacture of semi-automatic welding circuits.

A variable resistor of the controller is installed on the front panel of the inverter, after which they begin to assemble the relay for starting the motor and controlling the valve, which is responsible for supplying inert gas. The contact groups of the controllers must operate simultaneously when the start button on the burner is pressed.

The work of the gas supply must be adjusted so that the valve opens a few seconds before the wire begins to enter the welding zone. Otherwise, melting occurs in the atmospheric environment, after which the wire will begin to burn instead of the melt. It will be impossible to achieve a high-quality connection and a reliable welding seam when the wire burns.

To delay turning on the wire feed, you need to make a simple relay, which requires a capacitor and an 875 transistor. You can use the simplest relay from a car that connects to 12 volts on a computer power supply.

The valve itself can be used from various automotive locking devices. Easiest to change air valve from the car GAZ-24. You can also choose an electrovalve from a reducer from gas cylinders.

All available controls and the PWM wire feed controller of the semi-automatic welding machine are located on the front panel system block. A ready-made inverter with a power of at least 150 amperes is connected to the control unit and the wire feed controller with gas. It remains to carry out a test run and, if necessary, make appropriate adjustments to the operation of the welding wire and shielding gas supply system.

During operation, the power unit of the inverter semiautomatic device will heat up, which can lead to damage to the inverter and control boards. Repair of the unit after such breakdowns will be extremely difficult. To avoid this, it is necessary to install temperature sensors and coolers inside the inverter and the system unit, which can effectively cool the operating equipment.

You can use an optocoupler, which is connected to a common control unit for the operation of the equipment. If the temperature inside the inverter is exceeded, the sensors will send appropriate signals to the executive relay, which will turn off the power supply until the device is completely cooled down.

Additionally, various coolers from old computers can be used to cool the system unit. Coolers will vary in size. You can choose a fan that will cope with high-quality cooling of the system unit, inside which there is an inverter and other automation. The cooler used is connected to a 12-volt power supply directly or through a thermal sensor, which, when the temperature inside the case rises, will send a signal to supply voltage. The control unit will turn on the fan, which guarantees rapid cooling of the body of the semi-automatic device.

Assembling a semi-automatic welding machine is not particularly difficult, so every homeowner can handle this job. It is only necessary to use a high-quality powerful inverter, and it is best to take a burner with a drive from industrial factory semi-automatic machines. This will greatly simplify the manufacture of equipment. On the Internet, you can find various schemes for the execution of semi-automatic welding machines, which will not be difficult to implement. Such a device will differ in functionality and versatility in use..