Conversion of AC welding to DC welding. Converting the inverter into a semiautomatic welding machine

A semiautomatic welding device for household needs can be purchased in a ready-to-use form or completely assembled by hand. A self-made semiautomatic device will cost the performer much cheaper, but its assembly will require certain skills in working with electrical equipment. Appearance such a welded device is shown in the figure below.

For everyone who wants to make a semiautomatic device from an inverter with their own hands, we recommend that you first familiarize yourself with the device of this unit and the features of the functioning of its modules.

What you need to rework the inverter

Before you do semi-automatic welding do it yourself, you will need to prepare the following functional modules and spare parts that provide the required complete set of prefabricated equipment:

• An old inverter unit designed for a welding current of about 150 Amperes;
• Another working unit of the future semiautomatic device is the so-called "burner";
• A special feeder, with the help of which it will be possible to organize the delivery of welding wire to the place of work;
• Hoses that provide the supply of wire and shielding gas to a homemade welding unit (more precisely, to the area of ​​production of working operations);
• Redesigned for new needs a coil with a special wire placed on it;
• A separate electronic module that controls the functioning of everything homemade device(including converter transformer).

WITH complete set nodes and modules required for the semiautomatic device can be found in the figure below.

Unit device

Consider the most important parts of self-made units from an inverter in more detail.

Consumable supply assembly and torch

When completing with spare parts, special attention should be paid to a thorough alteration of the wire feeder, which will have to move inside the flexible hose.

To obtain a high-quality and accurate weld seam, the wire feed speed must be synchronized with the melting rate of its working part.

Since when welding with a semiautomatic device, it is allowed to use several types of wire made of various materials and having a different diameter, the rate of its entry must necessarily be variable... It is this opportunity that should be provided by the so-called "feed" consumable, which is organized in accordance with general requirements to any inverter unit.

When arranging a semi-automatic circuit, consumable wire with sections of 0.8, 1.0, 1.2 and 1.6 mm is most often used. Immediately before starting work, it is wound on pre-prepared coils, which are fixed on the elements of the unit by means of the simplest fasteners. Semi-automatic welding assumes a "self-propelled" wire feed, which significantly reduces the time of all operations and increases the efficiency of these procedures.

The torch used in a semiautomatic device can be taken entirely from an inoperative welding machine of the same type, or it can be made independently at home. Let's make a reservation right away that making a burner with your own hands is a completely difficult task, requiring the performer to have some experience and skills in making such devices.

Electronic control module

The electrical diagram of the semiautomatic welding machine is shown in the figure below.

The basic element of the semiautomatic device control unit is a microcontroller, which is responsible for selecting the load mode and for stabilizing the output current. In addition, the electronic unit includes the following mandatory assemblies and parts:

• High power semiconductor diode rectifier bridge;
• Key transistor circuits;
• Additional winding transformer;
• Correction chokes and inductors.

Particular attention in the composition of the electronic module should be paid to winding inductive products.

A simplified version of the inverter unit is known, which is commonly called the "device from Sanych". Its diagram is shown in the figure below.

Transformer

Another critical unit of a semiautomatic device, made by hand from an old welding device, is a transformer, which can be taken from the same inverter (taking into account a small alteration).

To ensure the required characteristics of the inverter transformer, completely suitable for a semiautomatic device, it is necessary to rewind the old primary coil with a copper strip coated with a layer of heat-resistant paper.

Important! Such transformers cannot be wound with conventional copper wire thick section, since in the mode of high current loads, they will be very hot.

The secondary winding of the old transformer product should also be slightly modified. To do this, you will need to do the following operations:

• First you need to wind a coil consisting of 3 layers of tin strips, each of which is insulated with a fluoroplastic tape;
• Further, the ends of the old and newly wound winding must be soldered, which will ensure high conductivity of the entire coil;
• You also need to provide in the set of elements from which the construction of the semiautomatic device is assembled, small fan(it is intended for additional cooling of the device).

A fan from a broken old PC can be used as such a cooling device installed in welding machines.

Assembly of the unit

Before making a semiautomatic device with your own hands, be sure to worry about checking all necessary parts old inverter. In addition, with the aim of improving thermal conditions the future device must be foreseen in it additional radiators, on which rectifiers and power diode switches are mounted (photo below).

Additional Information. In the spaces where the radiator units are to be located, it is necessary to provide thermal sensors that record the temperature in this part of the device.

After completing all the above procedures, you should proceed to docking the power module with the electronic control unit, after which you can try to connect it to the network and check it in operation.

Inverter setting

To carry out this mandatory procedure, first of all, it is necessary to connect the oscilloscope probes to the output terminals of the inverter converter, through which it will be possible to investigate the shape of the intermediate signals.

Note! The oscilloscope display should show electrical impulses with a frequency of about 40-50 kHz (see the figure below).

The time between individual bursts of such pulses should be equal to 1.5 μs (it can be adjusted by changing the input voltage). The magnitude of the control potential applied to the input of the converter is usually measured using an electronic voltmeter.

In the process of tuning the conversion system, it is also necessary to monitor the shape of the pulses observed at the output, which should approach rectangular with edges with a duration of no more than 500 ns. If all of the above parameters comply with the standard values, you can proceed to setting the load part of the inverter device.

The maximum current generated at the output of the operating unit should have a value of the order of 120 Amperes (its value can be measured using special clamp meters). In addition to the current component, after turning on the device, it is mandatory to monitor the temperature sensors installed in the area of ​​the radiators.

On final stage When the device is put into operation, it is necessary to check its operability under load. To do this, a sufficiently "powerful" rheostat with an active resistance of about 0.5 Ohm should be connected to the welding wires.

Important! This adjustment device must be rated for currents of at least 60 Amperes, which are controlled by means of an ammeter built into the device.

If the rheostat selected for tuning does not provide the required current value, its nominal resistance should be selected empirically.

Testing a semiautomatic device in work

After starting the self-assembled semiautomatic device, the current value corresponding to the operating value of 120 Amperes should be displayed on its indicator board. At the same time, you should check the readings of the sensors installed on the cooling radiators. homemade product(the temperature in the area of ​​their action should not exceed 100 degrees).

You will also need to check the adjustment range of the output (load) current, which cannot be less than 20-160 Amperes.

In conclusion, we note that a semi-automatic machine made by hand in compliance with all the rules considered in this review can serve its owner for a long time. Its performance and reliability will largely depend on the quality of the components used and the reliability of their assembly.

Video

If you decide to assemble a semiautomatic welding machine with your own hands from an inverter, the diagram and detailed instructions will become indispensable companions on the way to achieving this goal. The easiest way is to purchase factory semiautomatic devices such as Kedr 160, Kaiser Mig 300 with the required Ampere rating. But many people strive to do everything with their own hands. It's not so easy, but if you want to achieve a positive result, you will be able to.

Mig, Mag, MMA welding requires the use of appropriate devices. Mig Mag is a semi-automatic welding performed in an inert argon gas environment. Sometimes carbon dioxide is used for welding Mig Mag. MMA welding is called manual arc treatment with electrodes on which a special coating is applied. If you work with stainless steel, then MMA welding is carried out only with direct current.

Since we are talking about how you can assemble a full-fledged semi-automatic machine based on an inverter with your own hands, you are not interested in MMA, but in Mig Mag welding.

To collect homemade apparatus, a worthy analogue for Kedr 160, Kaiser Mig 300, with your own hands, you will need a diagram, video instructions and the necessary structural elements of a semiautomatic device. These include:

• Inverter. Determine its welding ability by selecting the applied current. Usually craftsmen assemble devices capable of delivering 150 Amperes, 170 Amperes or 190 Amperes. The more Amperes, the higher the capabilities of your welding device;
• Feeding mechanism. We will tell you about it separately;
• Burner;
• Electrode supply hose;
• Coil with special wire. This attachment is easily attached to the structure in any way convenient for you;
• Control unit for your welding machine.

Now for the semiautomatic feed mechanism and some important points.

1. He is responsible for the supply of electrodes using a flexible hose to the welding point.
2. The optimum wire feed rate is the same as the wire melting rate for DIY welding.
3. The quality of the seam obtained with your own hands depends on the wire feed speed.
4. It is recommended to make a semiautomatic device with the ability to adjust the speed. This will allow the semiautomatic device to be adapted to different type used electrodes.
5. The most popular electrode wires have a diameter of 0.8 to 1.6 mm. It needs to be wound on a coil and the inverter charged.
6. If you provide a fully automated feed, you do not have to do it yourself, and therefore the time spent on welding activities will be significantly reduced.
7. The control unit is equipped with an adjustment channel, which is responsible for stabilizing the current.
8. The behavior of the Ampere, that is, the current of the semiautomatic device, is regulated by a special microcontroller. It performs its work in a pulse-width mode of operation. The voltage created in the capacitor directly depends on its filling. This affects the parameters of the welding current.

Semi-automatic transformer preparation

So that a self-made semi-automatic machine works no worse than welding machine type Cedar 160, Kaiser Mig 300, it is necessary to understand the features of the preparation of the transformer.

• Wrap it with a copper strip. Its width should be 4 cm, and its thickness should be 30;
• Before this, the strip is wrapped with thermal paper. The material used in cash registers... It will not be difficult to acquire such paper;
• In this case, the circuit does not allow the use of ordinary thick wiring, otherwise it will begin to overheat greatly;
• The secondary winding must be done by using three layers of tin at once;
• PTFE tape is used to insulate each layer of sheet metal from each other;
• At the exit with your own hands, you will need to solder the ends-contacts from the secondary winding. This is necessary in order to increase the conductivity of the current;
• Be sure to provide a fan in the inverter housing. It will serve as a blow-off mechanism to reduce overheating of the equipment.

Inverter setting

There are no problems with the operation of Cedar 160, Kaiser Mig 300. Cedar 160 and Kaiser Mig 300 are factory equipments that have excellent specifications... These semiautomatic devices function perfectly, allow receiving required amount Amperes - 160 Amperes, 170, 190 Amperes, etc. It all depends on how you set up the device.

But if you decide to remake the inverter and make a semi-automatic out of it, then the idea of ​​buying a Cedar 160, Kaiser Mig 300 should be thrown aside.

After completing work with the transformer, you should go to the inverter. If you do correct settings the inverter itself, the alteration will bring the desired result. Therefore, a home-made semiautomatic device will function no worse than the finished Kedr 160, Kaiser Mig 300.

1. Be sure to provide for high efficiency heat sinks used for rectifiers (input and output) and power switches. Without them, the apparatus will not be able to work properly.
2. Inside the body of the radiator, which heats up the most, a thermal sensor should be installed to trigger it in case of overheating.
3. Connect the power section to the control unit and connect it to the working network.
4. When the indicator is activated, connect the oscilloscope to the wires.
5. Find bipolar impulses. Their frequency ranges from 40 to 50 kHz.
6. The parameters of the time between pulses are regulated by changing the input voltage. The time indicator should correspond to 1.5 μs.
7. Make sure the inverter is outputting square wave pulses on the oscilloscope. Fronts should not exceed 500 ns.
8. When the device has passed the test, connect it to the mains.
9. The indicator built into the semiautomatic device should produce 120 Amperes. Parameters can go up to 170, 190 Amperes. But if the device does not show given value, you will have to go in search of the causes of low voltage in the wires.
10. Usually similar situation occurs when the voltage is less than 100 V.
11. Now we are testing the semiautomatic welding machine by starting the machine with variable currents. At the same time, constantly monitor the voltage across the capacitor.
12. We conclude the testing by checking the temperature indicators.
13. Check how the apparatus behaves in case of a loaded state. Similar primary tests it is worth carrying out with Kedr 160 and Kaiser Mig 300. Although Kedr 160 and Kaiser Mig 300 are factory semiautomatic devices from trusted manufacturers, it will never be superfluous to make sure of their professional suitability.
14. To check a homemade inverter or Kedr 160 with a Kaiser Mig 300, you need to connect a 0.5 ohm load rheostat to the welding wires. Make sure the item can handle more than 60 Amps. The voltmeter controls the current parameters.
15. If the check of the semiautomatic device showed that the set value of the current and the controlled value differ, it will be necessary to change the resistances. Do this until you achieve a positive result.

Assembling a device that will act as a full-fledged analogue for the Kedr 160 and Kaiser Mig 300 is not so easy, but possible. You yourself determine whether the semiautomatic device will issue 120 or all 190 Amperes. Making the choice of the factory model easier. But their price is also appropriate. The price of the same semi-automatic Kedr 160 Mig is from 27 thousand rubles. But the decision is up to you.

The unit designed for welding products is considered to be a semiautomatic welding machine. Such devices can be different types and forms. But the most important is the inverter mechanism. It is necessary that it be of high quality, multifunctional and safe for the consumer. Most professional welders do not trust Chinese products, making their own devices. The scheme for making homemade inverters is quite simple. It is important to consider for what purpose the device will be made.

• Welding with flux-cored wire;
• Welding with various gases;
• Welding under a thick layer of flux;

Sometimes for a high-quality result and obtaining a smooth weld seam, the interaction of two devices is necessary.

Also inverter devices are divided into:

• Single-hull;
• Double-hull;
• Pushing;
• Pulling;
• Stationary;
• Mobile, which include a trolley;
• Portable;
• Designed for novice welders;
• Designed for semi-professional welders;
• Designed for professional craftsmen;

What is required?

A homemade apparatus, the scheme of which is very simple, includes several main elements:

• Mechanism with main function responsible for controlling the welding current;
• Mains power supply;
• Special burners;
• Convenient clips;
• Sleeves;
• Cart;

Welding scheme using a semiautomatic device in a shielded gas environment:

Also, the master will need:

• A mechanism that provides wire feed;
• Flexible hose through which the wire or powder will be supplied to weld under pressure;
• Spool of wire;
• Special control device;

Principle of operation

The operating principle of the inverter includes:

• Adjustment and movement of the burner;
• Control and supervision of the welding process;

When the unit is connected to the electrical network, a transformation is observed alternating current to permanent. For this procedure, you will need an electronic module, special rectifiers and a transformer with high frequency... For high-quality welding, it is necessary that the future unit has such parameters as the feed speed of a special wire, current and voltage in identical equilibrium. For these characteristics, you will need an arc power source that has volt-ampere readings. The length of the arc must be determined by the specified voltage. The wire feed speed is directly dependent on the welding current.