A semi-automatic welding machine is a functional device that can be purchased ready-made or made from. It should be noted that making a semi-automatic device from an inverter device is not an easy task, but it can be solved if desired. Those who set such a goal should thoroughly study the principle of operation of a semi-automatic device, look at thematic photos and videos, and prepare everything necessary equipment and components.
What is needed to convert an inverter into a semi-automatic machine?
To remake an inverter, making it functional semi-automatic welding, you should find the following equipment and additional components:
- an 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 the burner;
- a hose through which the welding wire will be fed;
- hose for supplying shielding gas to the welding area;
- a coil of welding wire (such a coil will need to undergo some modifications);
- the electronic unit, which controls the operation of your homemade semi-automatic machine.
Special attention should be devoted to redesigning the feeder, through which welding wire is supplied to the welding zone, moving along a flexible hose. To weld turned out to be of high quality, reliable and accurate, the speed of wire feeding through the flexible hose should correspond to the speed of its melting.
Since when welding using a semi-automatic machine, wire made from different materials and different diameters, its feed speed must be adjusted. It is precisely this function – regulation of the welding wire feed speed – that the feed mechanism of a semi-automatic device should perform.
Internal layout Wire reel Wire feeder (type 1)
Wire feed mechanism (type 2) Attaching the welding sleeve to the feed mechanism Design of a homemade torch
The most common wire diameters used in semi-automatic welding are 0.8; 1; 1.2 and 1.6 mm. Before welding, the wire is wound onto special reels, which are attachments of semi-automatic devices, secured to them using 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 regulation and stabilization welding current. The parameters of the operating current and the possibility of their regulation depend on this element of the electronic circuit of the semi-automatic welding machine.
How to convert an inverter transformer
In order for the inverter to be used for a homemade semi-automatic device, its transformer must be subjected to some modifications. It’s not difficult to do this kind of alteration yourself, you just need to follow certain rules.
To bring the characteristics of the inverter transformer into line with those required for a semi-automatic device, you should wrap it with a copper strip on which a thermal paper winding is applied. It must be borne in mind that for these purposes you cannot use ordinary thick wire, which will become very hot.
The secondary winding of the inverter transformer also needs to be redone. To do this, you need to do the following: wind a winding consisting of three layers of sheet metal, each of which must be insulated with fluoroplastic tape; Solder the ends of the existing winding and the one you made yourself together, which will increase the conductivity of 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 up an inverter used for semi-automatic welding
If you decide to make a semi-automatic welding machine with your own hands using an inverter, you must first turn off the power to 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 the 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 have been completed, you can connect the power part of the device to its control unit and connect it to electrical network. When the network connection indicator lights up, an oscilloscope should be connected to the inverter outputs. Using this device, you need to find electrical pulses 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 device input.
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 the checked parameters correspond to the required values, then you can connect the inverter to the electrical network. The current coming from the output of the semi-automatic device must have a force of at least 120 A. If the current value is less, this may mean that voltage is supplied to the equipment wires, the value of which does not exceed 100 V. If such a situation occurs, you must do the following: 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 machine has been tested, it is necessary to test 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 Ohm. Such a rheostat must withstand a current of 60 A. The strength of the current that in such a situation flows to the welding torch is controlled using an ammeter. If the current strength when using a load rheostat does not meet the required parameters, then the resistance value of this device is selected empirically.
How to use a welding inverter
After starting the semi-automatic device that you assembled with your own hands, the inverter indicator should display a current value of 120 A. If everything is done correctly, then this will happen. However, the inverter indicator may display a figure of eight. 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, the indicator will correctly show the strength of the welding current, which is adjusted using special buttons. The operating current adjustment interval, which is provided, is in the range of 20–160 A.
How to monitor the correct operation of equipment
So that the semi-automatic welding machine that you assembled with your own hands serves you long time, it is better to constantly monitor temperature regime inverter operation. To carry out such control, you need to press two buttons simultaneously, after which the temperature of the hottest inverter radiator will be displayed on the indicator. The normal operating temperature is considered to be one whose value does not exceed 75 degrees Celsius.
If given value is exceeded, then, in addition to the information displayed on the indicator, the inverter will begin to emit an intermittent sound signal, which you should immediately pay attention to. In this case (as well as if the temperature sensor breaks or shorts) electronic circuit The device will automatically reduce the operating current to 20A, and a sound signal will be emitted until the equipment returns to normal. In addition, a malfunction of self-made equipment may be indicated by an error code (Err) displayed on the inverter indicator.
With a good owner mandatory There should be a semi-automatic welding machine, especially for owners of cars and private property. You can always do small jobs with it yourself. If you need to weld a machine part, make a greenhouse or create some kind of metal structure, then such a device will become an indispensable assistant in private farming. Here a dilemma arises: buy or make it yourself. If you have an inverter, it’s easier to do it yourself. It will cost much less than buying in a retail chain. True, you will need at least basic knowledge of the basics of electronics, availability the necessary tool and desire.
Making a semi-automatic machine 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 It’s not difficult to do it yourself. You just need to have a good understanding of the intricacies of the work ahead and delve into the nuances of manufacturing. An inverter is a device that serves 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 - carbon dioxide. This guarantees a high-quality weld, 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 influence 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 supply hose;
- carbon dioxide cylinder;
- torch gun:
- spool of wire.
Welding station design
Principle of operation
When connecting the device to an electric the network is undergoing transformation alternating current to 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 parameters such as voltage, current and welding wire feed speed in a certain balance. This is facilitated by the use of an arc power source that has a rigid current-voltage characteristic. The length of the arc is determined by a rigidly specified voltage. The wire feed speed controls the welding current. This must be remembered in order to obtain from the device best results welding
The easiest way to use circuit diagram from Sanych, who long ago made such a semi-automatic machine 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 using this scheme, but also improved it. Here is the original source:
Diagram of a semi-automatic welding machine from Sanych
Semi-automatic Sanych
To make the transformer, Sanych used 4 cores from TS-720. I wound the primary winding copper wireØ 1.2 mm (number of turns 180+25+25+25+25), for the secondary winding I used an 8 mm 2 busbar (number of turns 35+35). The rectifier was assembled using a full-wave circuit. For the switch I chose a paired biscuit. I installed the diodes on the radiator so that they would not overheat during operation. The capacitor was placed in a device with a capacity of 30,000 microfarads. The filter choke was made on a core from TS-180. The power part is put into operation using a TKD511-DOD contactor. The power transformer is installed TS-40, rewound to a voltage of 15V. The roller of the broaching mechanism in this semi-automatic machine has a Ø 26 mm. It has a guide groove 1 mm deep and 0.5 mm wide. The regulator circuit operates at a voltage of 6V. It is sufficient to ensure optimal feeding of the welding wire.
How other craftsmen improved it, you can read messages on various forums dedicated to this issue and delve into the nuances of manufacturing.
Inverter setup
To provide quality work semi-automatic with small dimensions, it is best to use toroidal type transformers. They have the most high coefficient useful action.
The transformer for operation of the inverter is prepared as follows: it must be wrapped with a copper strip (40 mm wide, 30 mm thick), protected with thermal paper, of the required length. The secondary winding is made of 3 layers of sheet metal, insulated 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 operate smoothly and not overheat, it is necessary to install a fan.
Transformer winding diagram
Work on setting up the inverter begins with de-energizing the power section. Rectifiers (input and output) and power switches must have radiators 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 switched on. The network indicator should light up. You need to check the pulses using an oscilloscope. They should be rectangular.
Their repetition rate must be in the range of 40 ÷ 50 kHz, and they must have a time interval of 1.5 μs (the time is adjusted by changing the input voltage). The indicator should show at least 120A. It would not be superfluous to check the device under load. This is done by inserting a 0.5 ohm load rheostat into the welding leads. It must withstand a current of 60A. This is checked using a voltmeter.
A properly assembled inverter when performing welding work makes it possible to regulate the current in a wide range: from 20 to 160A, and the choice of operating current depends on the metal that needs to be welded.
For making an inverter with my own hands You can take a computer unit, which must be in working condition. The body needs to be strengthened by adding stiffeners. An electronic part is mounted in it, made according to Sanych’s scheme.
Wire feeding
Most often, such home-made semi-automatic machines provide the possibility of feeding welding wire Ø 0.8; 1.0; 1.2 and 1.6 mm. Its feeding speed must be adjusted. The feeding mechanism together with the welding torch can be purchased at a retail chain. If desired and available necessary details it is quite possible to do it yourself. Savvy innovators use an electric motor from car wipers, 2 bearings, 2 plates and a Ø 25 mm roller for this. The roller is installed on the motor shaft. Bearings are attached to the plates. They press themselves against the roller. Compression is carried out using a spring. The wire passes along special guides between the bearings and the roller and is pulled.
All components of the mechanism are installed on a plate with a thickness of at least 8-10 mm, made of textolite, and the wire should come out in the place where the connector connecting to the welding sleeve is installed. A coil with the required Ø and grade of wire is also installed here.
Pulling mechanism assembly
You can make a homemade burner with your own hands, using the figure below, where its components are shown clearly in disassembled form. Its purpose is to close the circuit and provide the supply of shielding gas and welding wire.
Homemade burner device
However, those who want to quickly produce a semi-automatic gun can buy a ready-made gun in a retail chain along with sleeves for supplying shielding gas and welding wire.
Balloon
To supply shielding gas to the combustion zone of the welding arc, it is best to purchase a standard type cylinder. If you use carbon dioxide as a shielding gas, you can use a fire extinguisher cylinder by removing the speaker from it. It must be remembered that it requires a special adapter, which is needed to install the reducer, since the threads on the cylinder do not match the threads on the neck of the fire extinguisher.
Semi-automatic with your own hands. Video
You can learn about the layout, assembly, and testing of a homemade semi-automatic machine from this video.
A do-it-yourself inverter semi-automatic welding machine has undoubted advantages:
- cheaper than store-bought counterparts;
- compact dimensions;
- the ability to weld thin metal even in hard-to-reach places;
- will become the pride of the person who created it with his own hands.
Among beginners and professional welders, an inverter-type semi-automatic welding machine is the most popular device. For the former, it provides ease in acquiring welding skills; for the latter, it provides productivity and a large range of additional settings.
Semi-automatic welding equipment can be useful for almost any welder, but has quite a few high cost. If available manual arc welding you can convert it into a semi-automatic inverter type.
Semi-automatic welding machine initially designed for working with filler wire in a protective gas environment (inert or active). Its difference from a conventional manual arc welding machine is the presence of a wire feed mechanism, a gas cylinder, a special torch and a gas and additive control unit.
The power source itself in the form of an inverter is no different. If the feed mechanism is built into the inverter housing, 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 homemade semi-automatic machine. 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 wishes of customers, have provided the required additional connectors. They help convert the device into a semi-automatic device as quickly as possible.
Some models of “Source” type inverter devices on the rear panel have a key for switching the operating mode from MMA to MIG and a connector for controlling on/off the inverter. usually equipped with a 3 m long Euro hose with a burner at one end and a connector at the other.
The connector allows you to feed welding wire and protective gas; in addition, a cable passes through it to supply control signals to the electric motor for drawing the additive and connecting the gas.
There is a special cable for connection to the inverter device. 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 mode, it will go to the MIG torch.
The second cable powers the feed mechanism from the inverter, if it has an appropriate connector, or from another low-power source direct current 12 V.
Before work, the required gas flow rate is set on the gas cylinder, and the feed rate of the additive is set on the feed mechanism. The inverter sets the welding current, the value of which depends on the thickness of the metal being welded.
Then start welding. As you can see, turning manual arc welding into semi-automatic does not require any modifications; it is enough to purchase the missing equipment. The only drawback is that the inverter will come with a pulling device attachment.
Pulling device
In more difficult case the manufacture of a semi-automatic machine consists of altering the arc welding inverter and creating a broaching device from scrap materials. If you had to repair an inverter device, then you can safely implement the second option.
A system unit is ideal as a housing for a drawing device for an inverter-type semi-automatic device. It is quite easy to open, yet spacious and durable.
This will allow you to simply adjust the pressure of the rollers and install the spool of wire. Another advantage of the system unit is that it is easy to make holes in it in the right places, and there is a built-in 12 Volt power supply. 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 the built-in components from scrap materials and try them on inside the box. After making sure that the selected layouts are correct, you can begin manufacturing the fasteners.
You can buy a reel for a semi-automatic machine ready-made or make it yourself. It is very simple to produce. The diameter of the cheeks 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 rollers and one guide roller and a spring. An electric motor from the wipers can be used as a broaching motor. As a base on which the parts will be attached, you need to use a three-millimeter metal sheet.
Holes are drilled in the plate in the right places for attaching the rollers and the electric motor shaft of the future semi-automatic device. Since one roller is a pressure roller, the hole for it is drilled in an oblong shape.
A pressure spring will press on it from above, the force of which is adjusted 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 alignment of the rollers and the axis of the MIG torch connector are in the same plane. This will prevent the wire from creasing 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 the semi-automatic welding machine you will need:
- 2 relays;
- diode;
- PWM regulator;
- capacitance with transistor and resistance;
- solenoid valve;
- wires.
The valve is required to allow gas to enter the welding zone. All components can be purchased at the used parts sale.
The control circuits in an inverter-type semi-automatic device may be different, but their essence is simple and is as follows.
When you press the button on the burner, both relays switch. The first supplies voltage to the valve that opens the gas supply.
The second relay supplies power to the wire feed motor. But its activation 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 necessary to draw wire without gas supply. For this case, an additional button is provided, which provides broaching, bypassing the gas relay.
Self-inductance from the valve is removed if a diode is connected. To power the MIG torch from the inverter, you need to install an additional one next to the Euro connector, through which the current will flow.
When you turn on the button on the burner, gas begins to flow, after a while the additive is supplied. The delay time is regulated by selected capacitance and resistor values. A pause in an inverter-type semi-automatic machine is necessary to protect the weld pool from exposure to atmospheric air with gas.
When the button is turned on, voltage is supplied to the capacitor. It is gradually charged, when it reaches certain value the transistor opens, which causes the relay to turn on.
Burner
You can also make a torch for an inverter-type semi-automatic welding machine yourself, but it’s easier to purchase inexpensive model with sufficient welding current.
If you manufacture it yourself, you will still need a Euro connector and a supply cable if you want to end up with an aesthetically pleasing semi-automatic welding machine. In addition to the welding current, you need to consider the length and flexibility of the hose.
Excessive softness of the hose leads to bending and, accordingly, braking of the wire. A good addition is a spring or powerful rubber seal at the connection points between the hose and the burner and the connector. This will prevent it from breaking in these places.
Inverter
The manual arc welding inverter also needs to be rebuilt. Although it can be used without modifications, the quality of welding will then be lower than that of factory semi-automatic welding machines. It's all about the current-voltage characteristics. The difference is minor, but it has an impact.
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, which 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 modification of the inverter and self-made devices for drawing filler wire, the result is semi-automatic welding equipment with good parameters. At the same time, you save money and get a lot of pleasure from the fact that you did everything yourself.
If you have to do professional welding, then it is better to purchase a ready-made semi-automatic machine. Today, the choice of these devices is wide, and it is quite possible to choose a budget model of acceptable quality.
If you decide to assemble a semi-automatic welding machine with your own hands from an inverter, diagram and detailed instructions will become indispensable companions on the way to achieving your goal. The easiest way is to purchase factory semi-automatic devices such as Kedr 160, Kaiser Mig 300 with the required Ampere rating. But many people strive to do everything themselves. It's not that easy, but if you want to, you can achieve a positive result.
Mig, Mag, MMA welding requires the use of appropriate devices. Mig Mag is a semi-automatic welding process that is performed in an inert argon gas environment. Sometimes carbon dioxide is used for Mig Mag welding. MMA welding is called manual arc processing with electrodes on which a special coating is applied. If you are working 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 assemble a homemade device, a worthy analogue for the Kedr 160, Kaiser Mig 300, with your own hands, you will need a diagram, video instructions and necessary elements semi-automatic designs. These include:
- Inverter. Determine its welding ability by selecting the supplied current. Typically, craftsmen assemble devices capable of delivering 150 Amps, 170 Amps or 190 Amps. The higher the Amps, the higher the ability of your welding device;
- Feeding mechanism. We will tell you about it separately;
- Burner;
- Hose for supplying electrodes;
- A spool of special wire. This attachment is easily attached to the structure in any way convenient for you;
- Control unit for your welding unit.
Now regarding the feed mechanism for a semi-automatic machine and some important points.
- It is responsible for supplying electrodes using flexible hose to the welding point.
- The optimal feed speed of the electrode wire corresponds to the speed of its melting at welding work with your own hands.
- The quality of the seam you make with your own hands depends on the wire feed speed.
- It is recommended to make a semi-automatic machine with the ability to adjust the speed. This will allow the semi-automatic machine to be adapted to different type electrodes used.
- The most popular electrode wires have a diameter from 0.8 to 1.6 mm. It must be wound on a reel and charged the inverter.
- If you provide fully automatic feeding, you will not have to do it yourself, and therefore the time spent on welding activities will be significantly reduced.
- The control unit is equipped with a control channel, which is responsible for stabilizing the current.
- The behavior of Amperes, that is, the current of a semi-automatic device, is regulated by a special microcontroller. It performs its work in pulse-width operating mode. The voltage created in the capacitor directly depends on its filling. This affects the welding current parameters.
Preparing a semi-automatic transformer
In order for a self-made semi-automatic machine to work no worse than a welding machine like Kedr 160, Kaiser Mig 300, you need to understand the features of transformer preparation.
- Wrap it with a copper strip. Its width should be 4 cm and thickness - 30;
- Before this, the strip is wrapped with thermal paper. Suitable material used in cash registers. It is not difficult to purchase such paper;
- In this case, the circuit does not allow the use of ordinary thick wiring, otherwise it will begin to overheat;
- The secondary winding must be made by using three layers of tin at once;
- PTFE tape is used to isolate each layer of sheet metal from each other;
- At the output, you will need to solder the contact ends from the secondary winding with your own hands. This is necessary in order to increase current conductivity;
- Be sure to include a fan in the inverter housing. It will serve as a blowing mechanism that reduces equipment overheating.
Inverter setup
There are no problems with the operation of Kedr 160 and Kaiser Mig 300. Cedar 160 and Kaiser Mig 300 are factory equipment that have excellent specifications. These semi-automatic machines function perfectly and allow you to get required amount Ampere - 160 Ampere, 170, 190 Ampere, etc. It all depends on how you configure the device.
But if you decide to remake the inverter and make it a semi-automatic device, then the idea of buying Kedr 160, Kaiser Mig 300 should be thrown aside.
After completing work with the transformer, you should move on to the inverter. If you do correct settings the inverter itself, alteration will bring the desired result. Therefore, a homemade semi-automatic machine will function no worse than a ready-made Kedr 160 or Kaiser Mig 300 device.
- Be sure to provide high-efficiency radiators used for rectifiers (input and output) and power switches. Without them, the device will not be able to work properly.
- A temperature sensor should be installed inside the radiator housing, which heats up the most, to trigger it in case of overheating.
- Connect the power part to the control unit and plug it into the working network.
- When the indicator is activated, you should connect an oscilloscope to the wires.
- Find bipolar impulses. Their frequency ranges from 40 to 50 kHz.
- The time parameters between pulses are adjusted by changing the input voltage. The time indicator must correspond to 1.5 μs.
- Make sure that the inverter produces square wave pulses on the oscilloscope. The edges should not exceed 500 ns.
- When the device has passed the test, connect it to the power supply.
- The indicator built into the semiautomatic device should produce 120 Amperes. Parameters can reach up to 170, 190 Amperes. But if the device does not show this value, you will have to go in search of the reasons low voltage in the wires.
- Typically, this situation occurs when the voltage is less than 100 V.
- Now we test the semi-automatic welding machine, starting the device with variable current. At the same time, constantly monitor the voltage on the capacitor.
- We complete the testing by checking the temperature readings.
- Check how the device behaves when loaded. Similar initial tests should be carried out with the Kedr 160 and Kaiser Mig 300. Although the Kedr 160 and Kaiser Mig 300 are factory semi-automatic machines from trusted manufacturers, it will never be superfluous to make sure of their professional suitability.
- To check homemade inverter or Cedar 160 with Kaiser Mig 300, you need to connect a 0.5 Ohm load rheostat to the welding wires. Make sure this element can withstand a load greater than 60 Amps. The current parameters are monitored with a voltmeter.
- If checking the semi-automatic device shows that the specified current value and the controlled value are different, the resistance will need to be changed. 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 simple, but it is possible. You yourself determine whether the semi-automatic device will produce 120 or all 190 Amperes. Make choosing a factory model easier. But their price is appropriate. The price of the same semi-automatic Kedr 160 Mig is from 27 thousand rubles. But the decision is yours to make.