Welding machine change. We assemble a DC welding machine with our own hands. Preparation for manufacturing and design features

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.

semi-automatic welding machine originally 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.

The connector allows you to supply welding wire and shielding gas, in addition, a cable passes through it to supply control signals to the filler pulling electric motor and connect the gas.

There is a special cable for connection to the inverter apparatus. It must be connected to the connector through which welding current from the inverter entered 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 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.

Comments:

Any tool store can now offer a fairly large assortment of various welding machines of various price categories. Most welding units, up to 70%, are occupied by welding inverters, and other "welders" fall on transformer-type devices. Not all people can purchase an industrial product for the production of electricity. welding work and some want to do it themselves.

A home welding machine will not be able to perform complex tasks, but for small jobs there will be enough power.

What is electric welding

Compound metal products each other by heating the metal electric arc and its further fusion into an integral seam is called electric welding. The main equipment in such a welding process is the welding machine, and the main tool for connecting metal things is the electrode. The welding unit serves as a source of alternating or direct current, which, by means of an electrode, ignites an arc that melts the metal. The quality of the welded joint when welding with direct currents is much higher than the same joint made by "change". The experience of an electric welder should not be discounted, although welding inverters that are popular today allow high-quality welding of metals almost the first time. That is why for most of the various welding works, welding machines are used that use a direct current type in their work.

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The simplest welding machine: instructions

For small home welding work, you can assemble a home-made compact machine with low power. This, of course, is not an inverter, but a necessary thing. When solving the problem of creating a welding "assistant", you can use various design features.

The simplest device for welding is a welding transformer with two windings: mains and working. The network is calculated for the mains voltage, usually 220-240 volts, and the working one is calculated for a lower voltage from 70 to 45 volts, and the change in current usually occurs by changing the number of turns of the working winding, its taps. As iron for transformers, you can use old asynchronous motors or industrial step-down three-phase transformers of the TOZ type, etc.

The primary winding should be designed for 25 ampere current, the secondary or working one - for 160 A. This is reflected in the cross section of the wires used. For an approximate estimate of the current load per 1 sq. mm allow 10 A, for aluminum - 4 A. We determine the cross-sectional area of \u200b\u200bthe window of transformer iron in square meters. cm, then we find the number of turns of the windings, if the required amount for one volt is determined as 48 divided by the sectional area of the iron window of the transformer. Calculating the device is half the battle, the main thing is to assemble it.

The product created according to the calculations is the simplest welding device alternating current, the design of the apparatus depends on the materials used.

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Let's make a DC welding machine with our own hands

In order for AC welding machines to turn into DC "welders", it is necessary to limit the rate of current change with a choke and rectify the alternating current with diodes or a rectifier bridge.

Diodes must be capable of 200A output current and have sufficient cooling so that the first welding does not damage them. This fully applies to the throttle. The use of these devices in conjunction with an AC welding machine turns it into a DC machine. It becomes possible to weld with DC electrodes, and the range of weldable metals is expanding. Becomes available for welding stainless steel and cast iron. The welding machine can cook like an inverter, although here the welder needs quite a lot of experience.

Semi-automatic welding you can buy ready-made, but there are always people who try to make it with their own hands. This is not easy to do, but those who really want to assemble a semiautomatic device with their own hands will have to prepare all the necessary components in advance.

To make a semi-automatic welding machine from an inverter, you will need tools and materials:

an inverter that is capable of delivering a current of about 150 A;
feeder;
burner;
flexible hose;
wire spool, with some design changes;
welding inverter;
Control block.

The feed mechanism in this case deserves special attention: with its help, the electrode wire is fed through a flexible hose to the welding point. Ideally, the wire feed speed should match the melting speed consumable. The wire feed speed is very important for the welding process: the quality of the weld depends on it. It is necessary to provide for the possibility of speed control for the possibility of working with electrode wire different sizes from various materials. The most commonly used wire of the following diameters: 0.8 mm, 1 mm, 1.2 mm, 1.6 mm. It is wound on coils and the welding inverter is charged. Fully automatic feed wire to the welding torch significantly reduces the time spent on work.

The control unit of the semi-automatic welding machine has a control channel that stabilizes the current. The action of the current is controlled by the microcontroller in the pulse-width mode. The voltage on the capacitor directly depends on the filling of the pulse-width mode. It is this voltage that affects the strength of the welding current.

The subtleties of the transformer

There are small subtleties in the preparation of the transformer. The transformer must be wrapped with a copper strip (width - 40 mm, thickness - 30). Previously, the strip must be wrapped with thermal paper (suitable from a cash register). Winding a simple thick wire in this case is excluded, since it will heat up.

The secondary winding should consist of three layers of tin. It is necessary to isolate the layers from each other with fluoroplastic tape. At the output, it is necessary to solder the contact ends of the secondary winding. This is done in order to increase the conductivity of currents. It is imperative to provide for blowing by a fan in the inverter housing.

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How to set up the inverter?

If you decide to make a semiautomatic device with your own hands, first you need to de-energize the power unit. By the way, for the input and input rectifiers, as well as for power switches (previously soldered to copper substrates), the power unit must be provided good radiators. In the case of the most heated radiator, it is necessary to place a temperature sensor. Now the power unit is connected to the control unit and connected to the network. When the indicator lights up, you need to connect the oscilloscope Out1, Out2 to the wires. Now find bipolar pulses, the frequency of which should be 40-50 kHz. The time between them is corrected by changing the input voltage. The time value should be 1.5 µs.

The pulses on the oscilloscope should be rectangular with fronts no more than 500 ns. After checking the inverter, connect it to the mains. The indicator of the semi-automatic welding machine should show 120 A, if this inscription on the indicator does not light up, then it is necessary to look for and eliminate the cause of low voltage in the welding wires. This situation occurs if the voltage is less than 100 V. After that, it is required to test the welding inverter by changing the current (with constant monitoring of the voltage on the capacitor). Then you can check the temperature.

After the welding inverter has been tested, it is necessary to check how it behaves under load. To do this, a 0.5 Ohm load rheostat is included in the welding wires, which must withstand a current of more than 60 A. In this state, the current is controlled using a voltmeter.

If there are discrepancies between the set value of the current and its controlled value, it will be necessary to select the resistance until a match is reached.

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Rules for using a welding inverter

By default, when you start the inverter, the controller will automatically set the current size. If all the steps indicated earlier are performed correctly, then the welding current will be 120 A. If it suddenly turns out that eights appear on the indicator, this will indicate a malfunction. Such malfunctions occur when the voltage in the welding wires does not rise more than 100 V. If this happens, then you will have to look for and fix the malfunction.

When everything is done correctly, a number should be displayed in place of the eights, indicating the amount of the given current. Using the buttons, this value can be changed, depending on what value of welding current is required in each specific case. The interval in which it is possible to change the current value varies from 20 A to 160 A.

It is possible to control the temperature of the inverter during the whole process. To do this, press both buttons at the same time. After that, it will be possible to observe the change in the temperature of the radiator, the data of which will be displayed on the indicator. Normally, the temperature of the heatsink should not exceed 75°C. If the temperature rises more than 75°C, it will immediately be displayed on the indicator, and the inverter will start beeping intermittent type. If this happens, the set current will automatically decrease to 20A. Although the current will be sharply reduced, the inverter will continue to work. This beep will sound until the display temperature returns to normal.

The indicator may give an error code Ert: this will happen in the event of a breakdown or short circuit of the temperature sensor.

In this case, in the same way, the set current will be reduced to 20 A.

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 bank.

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.

A good owner must have a semi-automatic welding machine, 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 for stepping down 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 converts alternating current to direct current. 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 feed rate. welding wire were 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.

Easiest to use 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 device 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 C). 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 quickly make a semi-automatic 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.