How to convert a welding inverter into a semi-automatic one

We make a semi-automatic welding machine from an inverter

Modern manufacturers produce a large number of welding inverters with a wide range of functions. These include semi-automatic machines operating in MIG/MAG mode, which means supplying inert or active gas and welding wire to the joint 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 machines is finding more and more followers, since it is possible to save significant amounts.

We will consider the possibility of such a modification and the necessary details for this.

The main differences between a welding inverter and a semi-automatic machine

Often, the master is faced with the question of choosing between an inverter or a semi-automatic welding machine, 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, with piece electrodes of different thicknesses, then semi-automatic welding machines connect parts with welding wire.

It is fed into the melting zone at a controlled speed and has different thicknesses, and to ensure the best result, the process takes place in an inert or active gas (MIG/MAG) environment.

Semi-automatic machines allow you to weld 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 semi-automatic welding machine contains an inverter, but also contains an adjustable wire feed unit and a special hose with a torch and cylinder. This equipment can weld aluminum alloys, carbon and stainless steel, cast iron and titanium, and with special wire - brass and galvanized metal.

When assembling a semi-automatic machine 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;
a torch with the ability to supply welding wire and the corresponding gas to the place of welding work;
a hose reinforced with a spring to ensure uninterrupted supply of wire and gas;
gas cylinder with reducer and pressure gauge;
reverse welding cable with clamp;
Control block;
reliable, adjustable unit for feeding welding wire of various thicknesses.

These elements can be purchased factory-made, and some of them can be made by hand. The inverter, burner and gas cylinder must be purchased from the manufacturer, since the technical requirements for these components require a quality certificate.

Construction of a torch and hose for a 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 piece 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, use a device consisting of the following components:

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

Creating a Euro-sleeve yourself is quite difficult; 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 any hindrance. For this purpose, the channel is equipped with a spring, using a Teflon coating; in addition, a gas supply passes through the same hose.

The control signal from the burner button also passes through the cable, and at the end there is usually a multi-pin Euro connector, through which all components are turned on and supplied.

The complex design of the torch and its operation at high temperatures implies the presence of refractory nozzles with holes for different diameters of welding wire.

Gas is supplied through the torch, as well as the wire feeding 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 tight connections of gas hoses.

Feeder design

The process of assembling a semi-automatic welding machine with your own hands can take place either using a factory feeding device or its home-made version. In order to make it yourself, you need to understand what the factory product consists of, namely:

on the front panel there is a Euro connector for connecting a welding sleeve;
on the back of the case there is a toggle switch for turning on the power supply and connectors for connecting to the inverter and gas supply system;
inside the case there is a power supply unit for the feeding device;
feed unit with a fixed, freely rotating spool of wire;
Next there is a clamping, adjustable feeding device connected through a gearbox to the electric motor shaft;
circuit for adjusting the speed of the electric motor, ensuring the forward 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 tubes to the solenoid and Euro connector;
power cable supplying welding current to the wire feed unit;
a scheme for coordinating gas supply and wire movement with a delay of 1-2 seconds, preventing burnout or sticking of the wire when working in an aggressive oxygen environment;
cables connecting the inverter and the feeder.

It is important that the feed system be mounted on electrically insulating material, since the welding wire is energized and acts as an electrode, and electrical contact with the equipment frame must be prevented.

It is necessary to ensure effective adjustable pressure on the feed roller, since the wire has a different cross-section, depending on the thickness of the workpieces being welded.

It is important to ensure the ratio of all nodes involved in ensuring the translational movement of the wire in order to avoid kinks that impede smooth feeding 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 won’t be difficult to choose a power supply with suitable parameters that will ensure the operation of the electric motor and electronic circuits of the feeder.

Step-by-step assembly of a semi-automatic device

When converting inverters into semi-automatic machines, it is necessary to take into account some circumstances. When purchasing 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 using a soldering iron.

It is important to match the reference and output voltages by installing a divider and selecting the component values for supplying a signal to the controller inputs.

Further steps for assembling a semi-automatic machine from a welding inverter, a feeder and a Euro-sleeve with a torch 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 supply device, and also adjust the flow of 6-10 liters per minute depending on the gas composition and welding conditions;
install and secure the wire reel into the feed unit;
using the speed control circuit, set the required feed speed of the welding wire and make sure that it moves unhindered;
connect the burner to the euro-sleeve, which, in turn, connects to the feeder;
turn on the inverter and feeding equipment and make sure there is a delay of 1-2 seconds between the arrival of gas and the movement of the wire.

Correct 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 work.

Let's sum it up

We looked at some ways to convert welding inverters into semi-automatic machines with our own hands. This is a fairly complex task, but upon close examination it is not particularly difficult. It is only important to ensure reliable operation of the elements and electrical safety. The main thing is that these efforts and temporary losses will provide very significant savings.

Source: https://electrod.biz/apparat/modifications/delaem-svarochnyiy-poluavtomat-iz-invertora.html

Do-it-yourself semi-automatic welding machine from an inverter

A semi-automatic welding machine is a functional device that allows you to weld various types of metal. Such a device can be purchased ready-made, or you can make it yourself from an inverter.

To make a semi-automatic device from an inverter will require a lot of effort and relevant knowledge, but if you strive, you can achieve your plan.

For those who decide to try assembling this device, you will need to research the scheme by which the semi-automatic machine works, watching various videos with photographs, and also get the required parts and accessories.

What is needed to convert the inverter into a semi-automatic machine?

To convert the inverter into a functional semi-automatic welding machine, you will need the necessary accessories and components:

An inverter that is capable of generating a welding current of 150A;
The mechanism responsible for supplying filler material and wire;

A torch, which is an important welding device;
The hose through which the filler material is supplied;
A hose through which protective gas flows to the junction of metals for better formation of a seam;
A filler material spool that will need to be converted for future equipment.
An electronic unit that will ultimately control the process of a homemade semi-automatic machine.

An important point is the restructuring of the device to supply filler material to the connection zone, which passes through a flexible hose . In order for the process to proceed normally without any difficulties, it will be necessary to correctly implement the speed of movement of the filler material, for a more beautiful formation of the seam, in accordance with the melting of the wire.

It is necessary to pay due attention to the adjustment, because when working with a semi-automatic machine, wire of different materials and thicknesses can be used. This device was invented precisely because of this function, so the semi-automatic feed mechanism needs to perform it at the required level.

Wires for semi-automatic machines are used in different diameters, but the most basic and common are 0.8; 1; 1.2 and 1.6 mm.

Before carrying out the welding process, the wire must be prepared by winding it on the required reel, which is a semi-automatic attachment, which is attached to it thanks to simple design devices.

During the welding process, filler material is supplied automatically, which is very efficient in terms of time, which can be spent much more when working on other types of devices, thanks to this, the technological operation is considered much more popular and simplified.

The main part of the electrical circuit of the semi-automatic control unit is a microcontroller, the function of which is to regulate and stabilize the current for welding. It is precisely this part of the electrical circuit of a semi-automatic welding machine that produces the necessary current parameters for operation and makes possible adjustments.

How to rebuild an inverter

For the possible use of an inverter for a semi-automatic device, its transformer will need to be slightly rebuilt. To organize such a restructuring of the mechanism yourself, you just need to comply with the required rules.

In order for the characteristics of the inverter to coincide with the characteristics of the semi-automatic device, you will need to wrap it with a strip of copper, which should be wrapped with thermal paper. It should be remembered that in this case, it is not recommended to use a simple large-diameter wire, since it will still heat up .

It will also be necessary to redo the secondary winding of the inverter. In this case, you will need to wind a winding that is made of three layers of tin, all layers need to be insulated with fluoroplastic tape, and the ends of the finished winding must be soldered together with your own hands, thanks to which the current flow will increase.

The design diagram of the inverter used to connect it to a semi-automatic welding machine, it is recommended to purchase a fan, thanks to which the entire equipment body will be sufficiently cooled.

Settings of the inverter used for semi-automatic welding

If you decide to make your own semi-automatic welding machine using an inverter, you will first need to turn off the equipment. To protect the device from overheating, it is necessary to place its rectifiers (input and output) and power switches on radiators. Of course, the best way would be to mount a temperature sensor in the equipment case, where there is a radiator; it heats up more and will turn off the device if there is severe overheating.

When all the above steps have been completed, you can begin to connect the power part of the device with its control unit, and connect it to the electrical network. You will need to connect an oscilloscope to the inverter outputs when the power indicator lights up. For such a device, it is necessary to obtain electronic pulses with a frequency of 40-50 kHz.

THIS IS INTERESTING: What is the positive electrode called?

The formation between pulses will require a time of 1.5 μs, and they are adjusted by changing the voltage value that is supplied to the input of the device. When all parameters correspond to the values, it will be possible to connect the inverter to the electrical network. The current supplied from the inverter output must be at least 120A.

When the current is low, then most likely the equipment wires have insufficient voltage conductivity, with a value not exceeding 100V. In order to adjust the device to the required current supply, you will need to perform tests by changing the current strength (during the process, it is necessary to regularly monitor the voltage on the capacitor). Also, you will need to always monitor the internal temperature of the case.

If the semi-automatic machine passes all the tests, you will then need to carry out a load test. To do this, you need to connect a rheostat to the welding wires, which has a resistance of at least 0.5 Ohm. Such a rheostat must withstand a current of 60 A. In this case, the current strength that passes into the welding torch will be controlled using an adapter.

If the current strength at the time of using the rheostat with a load does not meet the requirements of the parameters, then the resistance value of such equipment is selected empirically.

How to use an inverter for welding

When the semi-automatic device, made by hand, starts up, a current value of 120 A will appear on the inverter screen. If the correct steps for manufacturing the device are followed, this value will be present, however, the screen may still show figure eights. This reason may be due to the fact that the voltage of the welding wires is not appropriate. It is recommended to eliminate the cause of such nuances immediately.

If everything is done correctly, the indicator will correctly show the current strength, which can be adjusted using the buttons. The operating current can be adjusted within 20-160A, which is provided by the inverter for welding.

Monitoring the correct operation of the device

In order for your semi-automatic welding machine to serve you for a long time at the required level, it is recommended to constantly monitor the temperature conditions of the inverter. For such control, you will need to press 2 buttons at once, due to which the temperature of the hottest inverter radiator will be shown on the screen.

The normal temperature for operation is one whose value is no more than 75 degrees Celsius. If this value is exceeded, in addition to the information displayed on the screen, the inverter will make noise, emitting intermittent sound signals, you must immediately take action on such sounds.

In this situation, and in the situation of damage or short circuit of the temperature sensor, the electrical circuit of the device will automatically reduce the operating current to 20A, and sound signals will be heard throughout the entire time until the device is normalized.

Also, if your home-made device becomes malfunctioning or is damaged, an error (Err) will be displayed on the inverter screen.

When is a semi-automatic welding machine used?

Semiautomatic is recommended for use in situations where it is necessary to achieve precise, careful welding of various parts made of steel.

Thanks to this equipment, which was made with our own hands, it is possible to weld various thin metals, which is very popular in working with vehicles.

The welding process itself is simple and does not require long training, but you will still need to take several lessons from popular welders.

Source: https://svarkagid.com/svarochnyjpoluavtomatsvoimi-rukami-iz-invertora/

Converting an inverter into a semi-automatic welding machine

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 a fairly high cost. If you have manual arc welding, you can convert it into a semi-automatic inverter type.

Difference from manual cooking

The semi-automatic welding machine is initially designed to work 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. Welding wire feeders are usually equipped with a 3 m long Euro hose with a torch 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 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 12 V 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 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 a more complex case, the manufacture of a semi-automatic machine involves reworking 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. The advantage of the system unit is that it is easy to make holes 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 a plastic pipe with the same rating can be used as an axis.

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 that 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 gradually charges, and when a certain value is reached, 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 is easier to purchase an 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 a strong rubber seal at the junction of the hose with the burner and 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-manufacturing of the filler wire drawing device, semi-automatic welding equipment with good parameters is obtained. 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.

Source: https://svaring.com/welding/apparaty/svarochnyj-poluavtomat-invertornogo-tipa

How to make a semi-automatic welding machine with your own hands from an inverter?

Reading time: 7 minutes

A semi-automatic machine is not just a tool for many craftsmen. This is a complete assistant in the household and at work. Every craftsman may need it: from a summer resident to a car enthusiast. After all, the semi-automatic machine is excellent for welding all types of metals with virtually no restrictions on thickness and composition. At the same time, welding can be both professional and amateur.

Semi-automatic devices appeared on mass market not long ago. Old-school welders remember how they used to weld metal using large, bulky transformers. However, with the development of technological progress, engineers managed to design a compact and convenient semi-automatic machine. At the beginning of the 20th century, it supplanted the devices of the previous generation and won the respect of most welders around the world.

A modern semi-automatic machine is capable of performing various types of welding work. This can be MMA welding, MIG/MAG welding, as well as TIG welding. All this is possible thanks to the “stuffing” of the semi-automatic device. The device is based on a standard inverter. This means that, in theory, you can assemble a semi-automatic machine yourself. Of course, using the inverter as a “donor”. This article will cover everything: the basics of how a semi-automatic machine works, and how to convert a welding inverter into a semi-automatic machine.

THIS IS INTERESTING: How electrode brands are deciphered

Semi-automatic device

The structure of a semi-automatic machine is the first thing you need to study if you want to assemble your own machine.

A standard semi-automatic machine consists of two parts (or two blocks): power and feed. The feed part is simply a feed device for semi-automatic welding. But, let's take a closer look at the semi-automatic device.

The power part, also known as the power unit, is essentially an inverter. The inverter acts as a current source. Everything is simple here. But the feeding part is a separate, plug-in feeding mechanism. The feed mechanism is used to feed the wire. The wire is sold in reels and the reel is inserted directly into the feeder. Its end exits through the burner nozzle.

Of course, you don't have to use a feed mechanism to perform semi-automatic welding. The wire can also be fed manually. But this is extremely inconvenient, and in this case the whole essence of semi-automatic technology is lost.

That's all the components. This, of course, is not enough to make a semi-automatic welding machine on your own. You will also have to buy additional parts, but they depend on the type of inverter you have and the method by which you will convert it into a semi-automatic machine. Don’t forget about the components (burner, hose, correctly selected nozzle, etc.).

Principle of operation

The operating principle of the semi-automatic device is simple. It will be clear even to a beginner, so study this information carefully. It will be useful for assembling a homemade device.

So, it all starts with feeding the torch into the welding zone. The torch combines two devices: from its nozzle it supplies protective gas and wire simultaneously. The welder regulates the amount of gas manually, but the wire is fed in a semi-automatic mode (hence the name “semi-automatic”). That is why the welder always has only one hand occupied during the process. The one holding the burner.

As we have already said, gas is supplied to the welding zone simultaneously with the wire. An electric discharge is formed in the mixture of gases between the end of the wire and the metal surface, due to which the workpiece and the wire itself melt. Molten metal is mixed with molten wire. Next, you can form the seam.

In this case, wire is necessary and without it welding is simply impossible. Gas is also needed; it protects the weld pool from oxygen coming from outside. But if you do not have the opportunity to use gas, you can take a special cored wire and cook only with it.

Semiautomatic from inverter

There are several ways to make a working semi-automatic device from an inverter. We will list the most interesting, in our opinion. You can implement them at home with basic knowledge of electrical engineering.

Method No. 1

To make an inverter semi-automatic welding machine with your own hands, you will need a “donor”. Without it, it’s simply not possible to make a semi-automatic machine. As a “donor”, take not the weakest inverter for MMA welding. It must be operational and perform normal welding operations without any problems.

You need to change the current-voltage characteristics of the inverter you have chosen so that it can operate in semi-automatic welding mode. You can use a PWM controller for this. However, this option is very labor-intensive and is not suitable for those who are not strong in electrical engineering.

Therefore, in order to assemble a semi-automatic welding machine from an inverter with your own hands, we recommend making a choke. A choke from a fluorescent lamp is suitable for this. And after the throttle you need to take the feedback voltage. Watch the video below, which explains the essence of this method in detail. There is also a clear diagram in the video.

Method No. 2

The second method is extremely simple and is suitable for those who have a certain inverter welding. The fact is that there are inverters on sale that can switch to a mode with a rigid change in the current-voltage characteristic. If you are the owner of just such an inverter, then you can only be happy for yourself. To turn such a device into a semi-automatic machine, you just need to purchase an external feed mechanism.

The mechanism must include all the necessary cables and connectors. You just need to easily connect the welding wire feeder to the welding inverter and you can start welding. We can assume that in this case the feed mechanism works as an attachment to the inverter for semi-automatic welding. Watch the video below, where the author talks about his inverter, to which he connected the feeder.

Method No. 3

The last method of converting from a welding inverter into a semi-automatic machine with your own hands will require some knowledge and skills. In this case, you will also need a donor inverter. Please note that not every device will work. You need an inverter with ZX-7 layout. It must have a shunt at the output, and there must be a current transformer at the “primary”. It’s even better if the device doesn’t have any additional functions like hot start or arc force.

You also need to change the current-voltage characteristics, and also set the current rise setting. Further actions directly depend on the circuit of your inverter. So don’t be lazy to find topics on various forums dedicated to converting an inverter into a semi-automatic machine. Watch the video below with a test of such a homemade device.

Source: https://svarkaed.ru/oborudovanie-dlya-svarki/apparaty/samodelnye/kak-sdelat-svarochnyj-poluavtomat-svoimi-rukami-iz-invertora.html

Converting an inverter into a semi-automatic welding machine - Welding Profi

A semi-automatic welding machine is a functional device that can be purchased ready-made or made from an inverter with your own hands.

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 operating principle of a semi-automatic device, watch thematic photos and videos, and prepare all the necessary equipment and components.

Scheme of semi-automatic welding in a shielding gas environment

What is needed to convert an inverter into a semi-automatic machine?

To convert an inverter into a functional semi-automatic welding machine, you must 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);
an electronic unit that controls the operation of your homemade semi-automatic machine.

Electrical circuit of a 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. In order for the weld to be high-quality, reliable and accurate, the wire feed speed through the flexible hose must correspond to the speed of its melting.

Since when welding using a semi-automatic machine, wire of different materials and different diameters can be used, 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.

Appearance of a homemade semi-automatic welder

Internal layout Wire reel Wire feeder (type 1)
Wire feeder (type 2) Attaching the welding hose to the feeder 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, fixed 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 regulating and stabilizing the 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.

Converted inverter transformer

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 of the inverter 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.

Power diodes on additional radiators

After all of the above procedures have been completed, you can connect the power part of the device to its control unit and connect it to the 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.

Oscillogram of welding voltage and current: on the left with reverse polarity, on the right with direct polarity

It is also necessary to check that the pulses reflected on the oscilloscope screen are rectangular in shape, and their front is 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 be at least 120 A.

If the current value is less, this may mean that a voltage is supplied to the equipment wires, the value of which does not exceed 100 V. If such a situation arises, you must do the following: test the equipment by changing the current strength (in this case, you must constantly monitor the voltage on the capacitor).

In addition, the temperature inside the device should be constantly monitored.

The current strength that flows to the welding torch in such a situation 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 provided by welding inverters is in the range of 20–160 A.

Approximate modes of semi-automatic welding of butt seams

How to monitor the correct operation of 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 the temperature conditions of the inverter.

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 this value is exceeded, then, in addition to the information displayed on the indicator, the inverter will begin to emit an intermittent sound signal, which should be noted immediately.

In this case (as well as if the temperature sensor breaks or shorts), the electronic circuit of 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.

Setting the welding mode on the Resanta inverter

In what cases is a semi-automatic welding machine used?

Practice shows that it is better to use a semi-automatic machine in cases where it is necessary to obtain precise and accurate connections of parts made of steel. With the help of such equipment, which, if desired, can be made by hand, welded joints of thin metal are made, which is very important when repairing the body of a vehicle.

THIS IS INTERESTING: How to properly connect a semi-automatic welding machine

Source: https://fgpip.ru/pajka/peredelka-invertora-v-svarochnyj-poluavtomat.html

Converting the inverter to a semi-automatic machine

A semi-automatic welding machine is a functional device that can be purchased ready-made or made from an inverter with your own hands. 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 operating principle of a semi-automatic device, watch thematic photos and videos, and prepare all the necessary equipment and components.

Scheme of semi-automatic welding in a shielding gas environment

Converting a welding inverter into a semi-automatic machine with your own hands

Most craftsmen who work with iron consider the semi-automatic welding machine to be the most indispensable device in their arsenal. It is in demand among both professionals and beginners. Semi-automatic welding is mainly used in car body repair, but this is far from the only area of its application.

A ready-made machine can be purchased almost everywhere, but owners of ordinary welding inverters often do not want to buy another device. In this case, it is useful to know how to convert a welding inverter into a semi-automatic machine with your own hands. It is worth understanding that this is far from the easiest task, but with desire and some knowledge in the field of electrical engineering it is quite possible.

Required materials and tools

To assemble a semi-automatic machine you will need:

inverter welding machine with a current of at least 150 A;
burner with a special hose. Inside the hose there must be a gas pipeline, power and control cables, as well as a guide channel for the electrode wire;
wire feeding mechanism;
controller to the electric motor;
carbon dioxide cylinder;
solenoid valve;
wire spool;
12 V power supply, and a convenient case for assembling the mechanism.

Electrode feed mechanism assembly

The essence of semi-automatic welding is the controlled and continuous supply of the electrode directly to the torch using a special mechanism. It is quite possible to assemble it yourself. To do this you will need:

Car engine and windshield wiper mechanism.
System unit case and computer power supply. You can use any other power supply, it is important that its current is designed for the engine power.
Connector for connecting a special hose.
Bearings, bolt, PVC tube, spring, plywood.
A pipe with a width corresponding to the internal diameter of the coil.

So, assembling the mechanism begins with determining the location of the coil in the body. The outer diameter inside the housing should be clearly marked. The reel must be installed in such a way that the remaining space is sufficient for mounting the power supply, hoses, motor and pulling part.

It is better to purchase the pulling device separately, but if desired, you can design it yourself. To do this, you will need to modify the windshield wiper mechanism. Roller guides should be installed in it. Their role can be played by ordinary bearings with a groove machined along them. A guide part is fixed in front of the bearings.

This can be a bolt drilled lengthwise of the appropriate size. A spring-loaded cambric for rigidity is pulled onto the bolt, inside which the electrode will pass. The elements of the mechanism on which the rollers are installed must be compressed together by a spring with the ability to adjust the compression.

A special connector for the hose is mounted in the outer part of the housing.

All guide elements must be centered relative to the position of the connector.

In the center of the marked area, a reel made of plastic pipe is installed under the coil. For its base you can use a piece of plywood.

Electrical component

The electrical component must also be assembled for the feeder. It consists of the following components:

controller for 12 V motor;
delay relay;
electric valve;

The electric motor must be connected through the controller. This will make it possible to adjust the electrode supply. The connection diagram is included with the controller. However, to perform this and all subsequent work, basic knowledge of electrical engineering will be required.

In order for the electrode to be supplied to the welding site with a slight delay, you need to install a motor delay relay. It can be made based on the KT815 transistor, as well as an electrolytic capacitor with a capacity of 200 - 1000 μF. The assembly of this circuit should be carried out by a person who is well versed in electronics.

The electronic valve is located in the housing in such a way that during operation of the mechanism it is not affected by moving elements. It is connected to the circuit so that when you press a button on the burner, the valve immediately opens.

At the last stage, minor modifications to the inverter itself are required. Because its current-voltage characteristics do not correspond to semi-automatic welding. The easiest way is to add a choke from a fluorescent lamp to the positive terminal, so that current flows through it.

It is quite possible to convert a welding inverter into a semi-automatic one, but as can be seen from everything described above, this is quite labor-intensive work that requires knowledge in electrical engineering.

Source: https://tehnopanorama.ru/instrumenty/peredelka-svarochnogo-invertora-v-poluavtomat-svoimi-rukami.html

Do-it-yourself semi-automatic inverter - review of the conversion

Any welder knows about the advantages of semi-automatic welding over manual electric welding. Due to their widespread use and low cost, MMA inverters are in the arsenal of many craftsmen. But with MIG welding it’s a different matter – these devices are more expensive. But there is a way out - you can make a semi-automatic device from an inverter with your own hands. If you delve into this issue, the matter turns out to be not so complicated.

Semi-automatic welding

There are fundamental differences between MMA and MIG welding. To operate a semi-automatic machine, you need carbon dioxide (or a mixture of carbon dioxide and argon) and electrode wire, which is fed to the welding site through a special hose. Those. The very principle of semi-automatic welding is more complicated, but it is universal and its use is justified. What is needed for the semi-automatic to work:

wire feeder;
burner;
hose for supplying wire and gas to the heating pad;
current source with constant voltage.
And to turn an inverter welding machine into a semi-automatic machine, you will need a tool, time and desire.

Preparation

Manufacturing a semi-automatic welding machine at home begins with planning the work. There are two options for manufacturing MIG welding from an inverter:

Completely make a semi-automatic welding machine with your own hands.
Only remake the inverter - buy a ready-made feeding mechanism.

In the first case, the cost of parts for the feeding device will be about 1000 rubles, excluding labor, of course. If a factory semi-automatic machine includes everything in one case, then a homemade one will consist of two parts:

Welding inverter.
Box with feeding mechanism and wire reel.

First, you need to decide on the body for the second part of the semi-automatic device. It is desirable that it be light and roomy. The feeding mechanism must be kept clean, otherwise the wire will feed jerkily; in addition, the reels must be changed periodically and the mechanism adjusted. Therefore, the drawer should be easy to close and open.

The ideal option is to use the old system unit:

neat appearance - it doesn’t really matter, but it’s much nicer when the insides of the homemade product don’t stick out and the semi-automatic machine made from an MMA inverter looks good;
light, closes;
the body is thin - it’s easy to make the necessary cutouts;
The gas valve and wire feed drive operate on 12 Volts. Therefore, a power supply from a computer will do, and it is already built into the case.

Now you need to estimate the size and location of future parts in the body. You can cut out approximate layouts from cardboard and check their relative position. After this, you can begin work.

The best option for electrode wire is a 5 kg coil. Its outer diameter is 200 mm, inner diameter is 50 mm. For the axis of rotation, you can use a PVC sewer pipe. Its outer diameter is 50 mm.

Feeder

The electrode wire must be fed continuously and evenly - then the welding will be of high quality. The feed speed must be adjusted. There are three options for how to make the device:

Buy a fully assembled mechanism. Expensive, but fast.
Buy feed reels only.
Do it all yourself.

If the third option is chosen, you will need:

two bearings, guide roller, tension spring;
motor for feeding wire - a motor from windshield wipers will do;
metal plate for fastening the mechanism.

One pressure bearing - it must be adjustable, the second serves as a support for the roller. Manufacturing principle:

holes are made on the plate for the motor shaft and for mounting bearings;
the motor is fixed behind the plate;
a guide roller is put on the shaft;
bearings are fixed at the top and bottom;

It is best to place the bearings on metal strips - one edge is bolted to the main plate, and a spring with an adjusting bolt is connected to the other.

The completed mechanism is placed in the housing so that the rollers are located in line with the burner connector, i.e., so that the wire does not break. A rigid tube must be installed in front of the rollers to align the wire.

Implementation of the electrical part

For this you will need:

two automotive relays;
diode;
PWM regulator for the engine;
capacitor with transistor;
idle solenoid valve - for supplying gas to the burner. Any VAZ model will do, for example from a V8;
wires.

The wire and gas supply control circuit is quite simple and is implemented as follows:

when you press the button on the burner, relay No. 1 and relay No. 2 are activated;
relay No. 1 turns on the gas supply valve;
relay No. 2 works in tandem with a capacitor and turns on the wire feed with a delay;
wire pulling is done with an additional button, bypassing the gas supply relay;
To remove self-induction from the solenoid valve, a diode is connected to it.
It is necessary to provide for connecting the burner to the power cable from the inverter. To do this, next to the Euro connector, you can install a quick-release connector and connect it to the burner.

The semi-automatic device has the following operating sequence:

The gas supply is turned on.
The wire feed starts with a slight delay.

This sequence is necessary so that the wire immediately enters the protective environment. If you make a semi-automatic machine without delay, the wire will stick. To implement it, you will need a capacitor and a transistor through which the motor control relay is connected. Operating principle:

voltage is applied to the capacitor;
it is charging;
current is supplied to the transistor;
the relay turns on.

The capacitance of the capacitor must be selected so that the delay is approximately 0.5 seconds - this is enough to fill the weld pool.

After assembly, the mechanism must be tested, and the manufacturing process can be seen on video.

Inverter conversion

To make a semi-automatic machine from a conventional inverter with your own hands, you will have to slightly alter its electrical part. If you connect an MMA inverter to the assembled case, you will be able to cook. But at the same time, the quality of welding will be far from that of a factory semi-automatic machine.

It's all about the current-voltage characteristics - current-voltage characteristics. The electric arc inverter produces a falling characteristic - the output voltage floats. And for the correct operation of a semi-automatic device, a strict characteristic is required - the device maintains a constant voltage at the output.

Therefore, in order to use your inverter as a current source, you need to change its current-voltage characteristic (volt-ampere characteristic). For this you will need:

toggle switch, wires;
variable resistor and two constant;

Getting a hard characteristic on an inverter is quite simple. To do this, you need to place a voltage divider in front of the shunt that controls the welding current. Fixed resistors are used for the divider. Now you can get the required millivolts, which will be proportional to the output voltage, not the current. There is only one drawback to this scheme - the arc is too rigid. To soften it, you can use a variable resistor, which is connected to the divider and the output of the shunt.

The advantage of this approach is that the arc stiffness can be adjusted - this setting is only available in professional semi-automatic machines. And the toggle switch switches the inverter between MMA and MIG modes.

Thus, converting an MMA inverter into a semi-automatic device, although not an easy task, is quite feasible. The result is a device that is not inferior to the factory ones in its characteristics. But at the same time it is much cheaper. The cost of such an alteration is 4-5 thousand rubles.

Source: https://svarkalegko.com/oborudovanie/kak-sdelat-poluavtomat-iz-invertora.html