How to convert a welding machine from alternating to permanent

We assemble a DC welding machine with our own hands

Any tool store can currently offer a fairly large assortment of various welding machines in various price categories. The majority of welding units, up to 70%, are occupied by welding inverters, and the rest of the “welders” are transformer-type devices. Not all people can purchase an industrial product for electric welding work, and some people want to make a welding machine with their own hands.

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

What is electric welding

Connecting metal products to each other by heating the metal with an electric arc and then fusing it into a permanent seam is called electric welding. The main equipment in such a welding process is a welding machine, and the main tool for joining metal things is an electrode.

The welding unit serves as a source of alternating or direct current, which, through 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 alternating currents. 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 jobs, welding machines are used that use direct current in their work.

The simplest welding machine: instructions

Diagram of a homemade DC welding machine.

For small home welding jobs, you can assemble a homemade compact device with low power. This is, of course, not an inverter, but a necessary thing. When solving the problem of creating a welding “assistant”, you can use various design features.

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

The primary winding must be designed for a 25-amp current, the secondary or working winding must be designed for 160 A. This is reflected in the cross-section of the wires used. For a rough estimate of the current load per 1 sq. mm we allow 10 A, for aluminum - 4 A.

We determine the cross-sectional area of the transformer iron window in square meters. cm, then we find the number of turns of the windings, if the required number for one volt is determined as 48, divided by the cross-sectional area of the transformer iron window.

Calculating the device is half the battle; the main thing is to assemble it.

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

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

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

The device of a homemade semi-automatic welding machine.

The diodes must correspond to an output current of 200 A and have sufficiently good 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 alternating current welding unit turns it into a direct current apparatus. Welding with DC electrodes becomes possible, and the range of welded metals expands. Stainless steel and cast iron become available for welding.

A welding machine can weld like an inverter, although the welder requires quite a lot of experience.

Precautions when working with welding electrical equipment

Welding is a rather dangerous and traumatic activity, and electric welding adds to it the possibility of electric shock to the welder.

The most important thing that an electric welder must clearly understand is that electric current is invisible and dangerous to life, but all equipment must be reliably grounded, and this grounding must be strong and visible. This simplest commandment saved many who kept it.

The presence of dangerous voltage for humans on ungrounded equipment will lead to electrical injury, while the same damage on a grounded unit will simply be turned off by a circuit breaker.

Another danger to humans is the ultraviolet spectrum of the electric arc, which affects the organs of vision (quickly) and the skin, causing burns. Therefore, the presence of protective special welding clothing and a mask for the welder is mandatory. Protect those around you from the welding arc, as they may get eye burns when looking at it.

Compliance with the stated rules will make welding work safe.

Source: https://moyakovka.ru/instrumenty/svarochnyi-apparat-postoyannogo-toka.html

How to convert a welding machine from AC to DC with your own hands

How to choose quality equipment? How not to make mistakes when buying? These and other questions plague every welder who knows about the difficulty of choosing a welding machine. We will talk about them in this article.

There are 2 types of modern welding mechanisms:

AC units (transformers for welding);
Direct current mechanisms (rectifiers, inverters).

The former are used much less frequently today. Although a quarter of a century ago such devices were at the peak of their popularity. This was due to the fact that there was simply no alternative.

Relevance of the issue

The main question for welders is considered to be: what current should the machine have in order for it to work for a long time and efficiently - unstable or static? It used to be much easier, because all the devices worked during breaks.

There was no difficult choice that arose literally 25 years ago. Today it is extremely difficult for an ordinary master to determine what will work better - inverters, transformers or rectifiers. It is worth dwelling on this issue in more detail.

What is alternating current? This is a standard electrical impulse that comes out of electrical outlets.

Old-style devices worked exactly on this principle: they connected a mechanism and received a couple of hundred Amps of welding current at the output. This was enough for successful work.

Today, technology is progressing, and devices are appearing that can change current from alternating to direct. But here's the catch: the inverter actually changes the AC to static. And this is not clear to everyone.

Our goal in this article is to tell you what both devices are. In addition, we will try to justify the importance of converting welding equipment from alternating current to direct current.

What's really going on?

Many welders were perplexed when new types of machines appeared on the market. Transformers turned out to be not as simple as their predecessors.

The reason for this was the characteristics of alternating current. Unstable arc burning led to crooked seams. This was especially true for the work of newcomers.

Among the disadvantages of such mechanisms were:

Loud noise during operation;
Inaccurate welding, metal spattering;
Difficulty working with the device.

A completely logical question arises: “Isn’t it better to use old equipment that generates alternating current?” Many masters, both with great and little experience, think about this controversial issue.

What can we say about beginners! Let's try to understand this issue.

Let's start with the advantages of the transformer. Their main advantages that outweigh the disadvantages:

Low cost of the device;
Works well with metals that have an oxide film - stainless steel and aluminum;
Can work with dirty parts if there is no way to clean them;
They do not have special conditions of use and storage;
Unpretentious to the place where work is performed;
They have good power and can weld even thick metal.

As you can see, there are many more advantages. This means that such a technique deserves attention.

Welding arc: what is it?

We said earlier that during operation the arc may burn unsteadily. The process is often noticeable to the naked eye: the welder does his job, and the arc deviates from the specified axis. As a result, the seam turns out uneven.

Beginners often make a lot of mistakes because they don’t know all the nuances. This is fraught with rapid extinction of the arc and incorrect operation.

Such moments suggest the uselessness of buying transformers for craftsmen without experience. But everything is somewhat different: if you learn to work with such a complex mechanism, then in the future you will not have difficulties with any other device.

If you are determined to abandon AC units, we will advise you on what to do. We will tell you what to do when you have already bought a transformer, but regretted it. Our goal is to tell you how to properly remake such a mechanism.

Why are changes needed?

As you already understand, it is impossible to say unequivocally which device is better - one operating on direct or alternating current. These are two different devices with their own advantages and disadvantages that should be taken into account when working.

Our advice is clear: buy universal equipment with two modifications.

There are such devices on the market. But they are quite expensive, so not everyone can buy them. Experienced craftsmen can safely take such a unit. Well, if you are a beginner and do not plan to carry out work too often, buy a transformer and remake it.

The latter works very smoothly. By modifying it a little, you will get a good device that can switch from alternating to direct current. This device will become a reliable assistant in any welding business.

How to remake a mechanism at home

The process seems very complicated, but it is not entirely true. You will succeed if you already have some experience in welding. The advantage of the conversion is that you do not need to buy another DC device.

You will assemble it with your own hands: it will look like an addition to the transformer. The operating principle of the device is quite simple. To do this, you connect it to a transformer and it changes the AC current to DC.

We offer a simple diagram of this design.

Let us explain what our drawing means. The small rectifier is assembled using diodes (VD1-VD4). L1 is the throttle. With the help of the latter, the arc will ignite easily and work much more efficiently.

This accessory will not be built into your transformer. It is a separate device. For the latter to work, you need to connect it to a variable transformer using wires.

Important points to consider when working:

Choose diodes from models D161-320, D161-250 or B200. They need to be carefully attached to the radiators.
Assemble the choke on the core, which applies to the TS-270 transformer. It is purchased from other welders or taken from a tube TV.
Remove all existing windings and replace them with new ones. The optimal number of turns is up to 30.
When working, use wires made of copper. Ideally, the cross-sectional area should be from 16 to 22 square millimeters.
Place PCB spacers between the core parts. The optimal thickness of the former is from 0.3 to 0.5 millimeters.

This is how you can easily improve the device and make it work on both direct and alternating current.

Let's sum it up

Every person involved in welding dreams of a universal mechanism that operates on direct and alternating current. But can a good device be inexpensive? The last condition is almost impossible to fulfill, because a ready-made mechanism costs a lot of money.

Of course, if you are an experienced welder who has a lot of orders every day, this is a good option. But what should a beginner do? After all, he is often not ready for big expenses.

In this case, golden hands and a couple of hours of free time will come to the rescue. Choose an inexpensive transformer, arm yourself with the support of an experienced friend - and you will be able to create a unique device.

The device will eventually be able to cook using direct current, and you will be satisfied with its performance. Even if you don't need the add-on, it's always convenient to have on hand. All parts for this design are easy to purchase. Or maybe they’re just collecting dust in your garage.

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Source: https://prosvarku.info/apparaty/peredelat-svarochnyj-apparat-peremennogo-toka-na-postoyannyj

How to convert an AC welding machine to a DC one?

Reading time: 7 minutes

AC and DC welding machines are used everywhere by both professionals and amateurs. Traditionally, welding transformers are classified as alternating current devices, and inverters and rectifiers are classified as direct current devices.

AC devices today are not used as often as alternating current devices. Although in the 20th century, alternating transformers were the most popular and widespread type of welding equipment.

In this article we will remind you what alternating and direct current are, how they differ, and at which current welding is easier and of better quality. You will also learn how to convert a welding machine from alternating to permanent, and why this is necessary.

general information

AC or DC - which is better? In the 21st century, this question haunts many welders. Previously, the welding machine would work intermittently in any case, and the master actually had no choice. But with the advent of rectifiers and inverters on the market, the choice has increased hundreds of times. And now it’s no longer easy to figure out which device to choose.

We decided to help you and tell you about the features of both alternating and direct current.

Let's start with a break. Alternating current is the basis. This is what we get from the outlet when we connect a welding machine or any other electrical appliance. Welders of the old format (transformers) worked on alternating current. Such a device made it possible to obtain a welding current of several hundred Amperes from 220 Volts. Which is more than enough for manual arc welding.

But times have changed. Technological progress did not stand still, and over time, devices appeared that learned to convert alternating current coming from the network into direct current. Such devices include a rectifier and an inverter. Please note that when they say AC welding inverter, they mean that this device uses alternating current for power, but converts it to direct current.

What does all this mean in practice?

When DC machines went on sale, welders had a unique opportunity to compare them with traditional alternating machines. And they were surprised. Compared to modern inverters and rectifiers, transformers were much more difficult to use.

It's all about the AC characteristics. Because of them, the arc is ignited reluctantly and burns unstable. As a result, the seams are less even and durable. This is especially noticeable when the work is performed by a less experienced craftsman.

It also turned out that AC machines generate more noise, which affects the welder’s performance. In addition, a classic transformer consumes more welding electrodes, and metal is constantly splashed during work.

At this point, you probably thought: “Well, why then do we need AC devices if they have so many disadvantages?” In fact, it's not that simple. It’s not for nothing that the question “Which is better: direct or alternating current?” raises so many questions and discussions.

Alternating devices (transformers) are indispensable when you need an inexpensive, but at the same time powerful and reliable welder. Also, alternating current welding has proven itself to be excellent when welding metals with an oxide film on the surface. These are, first of all, aluminum and stainless steel. Transformers also cope well with welding contaminated parts, if there is no way to clean and grind them.

Also, AC machines can easily handle welding in the field, are unpretentious to storage and operation, and can weld even the thickest metal due to their large power reserve.

A few words about the welding arc

We mentioned above that when welding with alternating current, the arc burns unstable. This is true, and this problem requires special attention if you are a novice welder. When we talk about instability, we mean that the arc seems to “walk” when forming a seam. It deviates from the axis, and sometimes this is even noticeable to the naked eye.

Source: https://svarkaed.ru/oborudovanie-dlya-svarki/apparaty/po-istochniku-toka/kak-peredelat-svarochnyj-apparat-peremennogo-toka-na-postoyannyj.html

Converting a welding machine from alternating to permanent - Metalworker's Handbook

According to experts, making a DC and AC welding machine with your own hands will not take much time and effort.

The main condition for its creation is a clear idea of what kind of welding work it should perform and instructions.

Features of the device

To carry out welding, you need a device that runs on alternating and direct current.

Thin metal sheets are welded using a current machine. This welding method does not require the use of a specific type of electrode, and the electrode wire can be without ceramic coating.

The welding machine circuit consists of 5 parts. The current circuit passes through the welding machine, first entering the transformer.

From there, the current flows into a rectifier, whose diodes convert alternating current to direct current, and a choke. The last elements of current flow are the holder and the electrode.

The electrode holder is connected to the rectifier using a throttle. This smoothes out the tension pulse.

A choke is a coil of copper wires wound around a core. And the rectifier is a part of the device connected to the transformer through the secondary winding.

A transformer is connected to the network - the main part of the device. You can either purchase it specially or use a previously used but usable transformer.

It converts AC voltage according to Ohm's law.

So the voltage generated on the secondary winding decreases, but at the same time the current increases 10 times. Welding occurs at a current of 40 amperes.

The electrical circuit is closed the moment an arc appears between the electrode and the pieces of metal being welded.

The arc must burn stably, then the weld will be made with high quality. An electrical power regulator will help in establishing the desired combustion pattern.

The most basic diagram of the unit

It is better if the electrical circuit of the unit is very basic.

An easy-to-assemble device, assembled with your own hands, must be connected to a network with an alternating current voltage of 220 Volts.

A voltage of 380 Volts requires a more complex welding machine design.

The simplest circuit is a circuit for the pulsed welding method, which was invented by radio amateurs. This welding is used to attach wires to a metal board.

To build this device with your own hands, you don’t need to do anything complicated, you only need a couple of wires and a choke. The choke can be removed from the fluorescent lamp.

The current regulator can easily be replaced with a fuse-link. It is better to stock up on large quantities of wires.

To connect the electrode to the board, take a choke. An alligator clip can serve as an electrode. The finished unit must be connected to the network by inserting a plug into the socket.

Using the clamp connected to the wire, you need to quickly touch the area to be welded on the board.

This is how a welding arc appears. During its occurrence, there is a danger that the fuses located in the electrical panel will burn out.

The fuses are protected from this danger by a fuse link that burns faster.

As a result, the wire remains welded to its place.

But it seems possible to work with it only at home, since this circuit is devoid of important parts - a rectifier and a current regulator.

Equipment for welding unit

Compared to traditional devices, a three-phase inverter-type unit is compact, easy to use, and reliable. There is only one nuance that makes you think about it during the purchase - the rather high price.

Even superficial calculations suggest that making a welding machine with your own hands will be cheaper.

If you approach the selection of the necessary elements with all seriousness, then a homemade welding tool will last a long period of time.

In general, the welding machine circuit consists of three blocks: a rectifier block, a power supply and an inverter block.

A homemade AC and DC apparatus can be equipped so that it can be light in weight and have a small size.

A homemade welding machine can be easily built with your own hands, using objects available to everyone.

All the parts needed to create a welding unit are available in electrical equipment or in devices where some elements have failed.

You can build a simple current regulator from part of the heating coil used in an electric stove.

If you couldn’t find any necessary parts at all, then it’s okay - you can make them yourself.

A piece of copper wire can serve as a material for creating such an important element of a DC and AC welding unit as a choke.

Specifically for its assembly you will need a magnetic circuit, which has an old starter. You also need 2-3 copper wires with a cross-section of 0.9 - and you can get a choke.

The transformer for the welding unit can be an autotransformer or the same part removed from an old microwave oven.

When removing the necessary element from it, you need to be careful not to damage the primary winding.

And the secondary one will have to be redone anyway; the number of new turns depends on the power of the unit being designed.

The rectifier is assembled on a board made of either getinax or textolite.

The diodes for the rectifier must correspond to the selected power of the unit. To keep them cool, an aluminum alloy radiator is used.

Sequential assembly of all parts

All elements of the welding unit must be located on a base made of metal or textolite strictly in their places.

According to the rules, the rectifier is adjacent to the transformer, and the inductor is located on the same board with the rectifier.

The current regulator is installed on the control panel. The frame itself for the structure of the unit is created from aluminum sheets; steel is also suitable for this.

You can also use a ready-made case, which previously protected the contents of the system unit of a computer or oscilloscope. The main thing is that it must be strong and solid.

A board with thyristors is placed at a great distance from the transformer. The rectifier is also not installed close to the transformer.

How to weld a vertical seam using arc welding

The reason for this arrangement is the strong heating of the transformer and inductor.

Thyristors mounted on aluminum radiators remove heat from the inductor. They even cancel out the heat waves emanating from the wires.

An electrode holder is attached to the outer panel, and a wire with a plug is attached to the rear panel to connect the unit to a household network.

The video in our article demonstrates how to assemble a welding unit with your own hands.

Under no circumstances should the elements of the unit be fixed close to each other, as they must be subject to airflow.

It is necessary to make holes on the sides of the frame from where air will flow. This is also necessary for installing a cooling system.

If the welding unit is constantly in the same place, then it is unlikely that anything will happen to it.

The current regulator, or more precisely, its handle fixed on the outer wall, will be able to work for a long time.

The product is assembled - it’s time to check how it functions. When testing the operation of the welding unit, temporary wires should not be used.

You need to check the product with standard contact cables.

During the very first connection to the network, look at the current regulator. It is important to ensure that there are no unfixed parts left.

If the unit is in good working order and free from defects, then you can start welding in various modes.

Source: https://ssk2121.com/peredelka-svarochnogo-apparata-iz-peremenki-v-postoyanku/

How to convert an alternating welding machine into a permanent one. We make a semi-automatic welding machine from an inverter

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

Design Features

A design feature of a semi-automatic welding machine is the constant supply of molten wire into the welding zone, which is used instead of metal electrodes.

Wire feeding is carried out automatically, with the ability to change the speed of movement of flexible electrodes.

The welding wire used will ensure constant contact of the surfaces being connected; such material, in comparison with standard electrodes, has less resistance, which improves the quality of the connection.

Semi-automatic welding is distinguished by its versatility, which allows using this technology to weld metals of various characteristics, including stainless steel, non-ferrous alloys, aluminum and others. Mastering the correct semi-automatic welding technique is not difficult.

Homemade devices are easy to use, so they can be recommended to ordinary homeowners.

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Depending on their type, semi-automatic machines may have an additional nozzle for supplying gas, and the metals are joined in a protective environment, which makes it possible to eliminate the subsequent formation of corrosion in the weld.

Welding inverters offered in stores today are distinguished by their versatility, and many of them have a two-in-one function. With low power and dimensions, a two-in-one semi-automatic machine can work with refractory metals and thick metal workpieces.

Many homeowners, who often have to perform welding work, decide to manufacture such equipment themselves. The advantages of homemade semi-automatic machines from an inverter include the following:

Among the disadvantages of this technology and the equipment itself, one can note the high cost of semi-automatic machines, which, with characteristics similar to the inverter, can have a price two to three times higher. It is not surprising that many homeowners decide to make the equipment themselves, which allows them to significantly reduce costs without losing the quality of the device.

DIY making

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

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

You can produce high-quality equipment if you have on hand the starting circuit for a semi-automatic welding inverter. The characteristics of such a unit include the following:

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

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

Required Components

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

Burner attachment for inverter.
Wire feed mechanism.
Durable internal welding wire hose.
Bobbin with wire.
Sealed gas supply hose.
Inverter control unit.

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

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

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

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

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

Mechanical control circuit

A small electric motor and a drawing mechanism, the operation of which is controlled using a PWM controller, will be responsible for feeding the welding wire. The quality of the welding performed will directly depend on the uniformity of the welding wire feed into the work area. It is necessary to pay due attention to the correct manufacture of semiautomatic welding circuits.

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

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

To delay the switching on of the wire feed, you need to make a simple relay, which will require a capacitor and an 875 transistor. You can use a simple relay from a car, which connects to 12 Volts on the computer power supply.

The valve itself can be used from various automotive locking devices. The easiest way is to remake the air valve from a GAZ-24 car. You can also choose an electric valve from a reducer from gas cylinders.

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

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

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

Additionally, to cool the system unit, you can use various coolers from old computers. Coolers will vary in size. You can choose a fan that will cope with high-quality cooling of the system unit, inside of which the inverter and other automation are located.

The cooler used is connected to a 12-volt power supply directly or through a thermal sensor, which, when the temperature inside the case increases, will send a signal to supply voltage. The control unit will turn on the fan, which guarantees rapid cooling of the body of the semi-automatic device.

Assembling a semi-automatic welding machine is not particularly difficult, so every homeowner can handle this work. You just need to use a high-quality, powerful inverter, and it is best to take a burner with a drive from industrial factory semi-automatic machines.

This will significantly simplify the production of equipment. On the Internet you can find various designs for semi-automatic welding machines, the implementation of which will not be difficult. Such a device will be distinguished by its functionality and versatility in use .

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.

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;

Source: https://provolp.ru/provans-i-kantri/kak-peredelat-peremennyi-svarochnyi-apparat-postoyannyi-delaem/

DIY DC welding machine assembly

According to experts, [making a welding machine] of direct and alternating current with your own hands will not take much time and effort.

The main condition for its creation is a clear idea of what kind of welding work it should perform and instructions.

How to make alternating welding permanent. Welding machine from

A semi-automatic welding device for household needs can be purchased ready-to-use or completely assembled with your own hands. A homemade semi-automatic machine will cost the performer much less, but its assembly will require certain skills in working with electrical equipment. The appearance of such a welded device is shown in the figure below.

We recommend that everyone who wants to make a semi-automatic machine from an inverter with their own hands first familiarize themselves with the structure of this unit and the operating features of the modules included in it.

What is needed to remake an inverter

Before making a semi-automatic welding machine with your own hands, you will need to prepare the following functional modules and spare parts that provide the required complete set of prefabricated equipment:

An old inverter unit designed for a welding current of about 150 Amps;
Another working unit of the future semi-automatic device is the so-called “burner”;
A special feeding mechanism, with the help of which it will be possible to organize the delivery of welding wire to the place of work;
Hoses that supply wire and shielding gas to a homemade welding unit (more precisely, to the area where work operations are performed);
A coil redesigned for new needs with a special wire placed on it;
A separate electronic module that controls the functioning of the entire home-made device (including the converter transformer).

The complete set of components and modules required for the semi-automatic machine can be found in the figure below.

Unit design

Let's look at the most important parts of units made by hand from an inverter in more detail.

Consumable supply unit and burner

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

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

Since semi-automatic welding allows the use of several types of wire, made of different materials and having different diameters, its flow rate must necessarily be variable. It is this opportunity that should be provided by the so-called “supply” of consumables, which is organized in accordance with the general requirements for any inverter unit.

When setting up a semi-automatic circuit, consumable wire with sections of 0.8, 1.0, 1.2 and 1.6 mm is most often used. Immediately before starting work, it is wound on pre-prepared reels, which are fixed to the elements of the unit using simple fasteners. Semi-automatic welding involves feeding the wire “self-propelled”, which significantly reduces the time of all operations and increases the efficiency of these procedures.

The torch used in a semi-automatic machine can be taken entirely from a non-working welding unit of the same type or made independently at home. Let’s immediately make a reservation that making a burner with your own hands is a very difficult task, requiring the performer to have certain experience and skills in the manufacture of such devices.

Electronic control module

The electrical circuit of the semi-automatic welding machine is shown in the figure below.

The basic element of the semi-automatic control unit is the microcontroller, which is responsible for selecting the load mode and stabilizing the output current. In addition, the electronic unit includes the following mandatory components and parts:

Rectifier bridge on high power semiconductor diodes;
Key transistor circuits;
Additional winding transformer;
Correction chokes and inductors.

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

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

Transformer

Another critical component of a semi-automatic machine, made with your own hands from an old welding device, is a transformer, which can be taken from the same inverter (subject to minor modifications).

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

THIS IS INTERESTING: How to properly cook with carbon dioxide using a semi-automatic device

Important! Such transformers cannot be wound with ordinary thick-section copper wire, since they will become very hot under high current loads.

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

First you need to wind a coil consisting of 3 layers of tin strips, each of which is insulated with fluoroplastic tape;
Next, the ends of the old and newly wound windings need to be soldered, which will ensure high conductivity of the entire coil;
It is also necessary to provide a small fan in the set of elements from which the semi-automatic design is assembled (it is intended for additional cooling of the device).

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

Assembly of the unit

Before making a semi-automatic machine with your own hands, be sure to check all the necessary parts of the old inverter. In addition, in order to improve the thermal conditions of the future device, it is necessary to provide additional radiators on which rectifiers and power diode switches are mounted (photo below).

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

After completing all of the above procedures, you should begin mating the power module with the electronic control unit, after which you can try to connect it to the network and check its operation.

Inverter setup

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

Note! Electrical pulses with a frequency of about 40-50 kHz should be observed on the screen of the oscilloscope device (see the figure below).

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

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

The maximum current generated at the output of a working unit should have a value of about 120 Amperes (its value can be measured using special current clamps). In addition to the current component, after putting the device into operation, it is necessary to monitor the temperature sensors installed in the area where the radiators are located.

At the final stage of putting the device into operation, it is necessary to check its functionality under load. To do this, a sufficiently “powerful” rheostat with an active resistance of about 0.5 Ohm should be connected to the welding wires.

Important! This adjusting device must be designed for currents of at least 60 Amperes, which are controlled using an ammeter built into the device.

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

Testing a semi-automatic device in operation

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

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

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

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.

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.

Source: https://assz.ru/kak-peremennogo-svarochnogo-sdelat-postoyannyi-svarochnyi-apparat-iz-peremenki/

Welding machine from

Structure

It is not difficult to convert an inverter into a semi-automatic welding machine for welding thin steel (low-alloy and corrosion-resistant) and aluminum alloys with your own hands. 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 the negative influence of air components (oxygen and nitrogen) by shielding gas.

The kit of such a semi-automatic device should include the following elements:

Source: https://criptopia.ru/chistka-i-uborka/svarochnyi-apparat-iz-peremenki-v-postoyanku-kak-sdelat/

Throttle L

The core for it is taken from the choke of city lighting lamps 1N400N37-110. When removing old windings, it is necessary to preserve the cardboard spacers that provided the gap between the main and closing parts of the core (Fig. 2).

Rice. 2 Choke design from the choke core of street lighting lamps.

When reassembling, they are installed in place. The new winding is wound on only one side core - three layers of copper busbar with a cross-section of 4x6 mm, located evenly 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 U01U04 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 radiator-coolers, which must be insulated from each other and from the body of the welding machine with textolite plates. Capacitors 31 56 - electrolytic, type K50-3 or K50-7, two-section 250/290 (150+150 µF). The total capacity of the capacitor block is 1800 microfarads. It is most convenient to install them in one row on a textolite plate 46 mm thick.

Welding current regulator P (“ballast rheostat”}

Made from one section of the limiting resistance of the DEK-256 overhead crane (Fig. 3 ).

This resistance is a ceramic pipe with a shaped spiral groove on the outer surface, into which a busbar made of a material with high resistivity, with a cross-section of about 20 mm2, is laid.

Rice. 3 Welding current regulator.

Source: https://www.mirpodelki.ru/index.php?id=215

Best answers

The inverter impresses with its light weight. .and there is another form of tension. .

lotions for easier ignition..

If you're not too lazy to carry your own. .

then it will be better to cook through a rectifier... than with a variable speed...

You can simply cook using electrodes for direct current. And the quality of welding depends on the welder. Although, of course, it is more convenient to cook with direct current, and the quality is better.

nothing like that! Until you put the CHOCK in place, the current will continue to be interrupted! DC electrodes do not “like” when the welding current goes to zero or fluctuates, but with a stupid diode bridge it passes through 0 100 times/sec.

The ONLY “plus” here is that the current does not change direction; the meaning of a QUALITY INVERTER, and not Chinese/Russian crap, is a constant stable welding current, the value of which does not change with changes in arc length and when changing the welding mode.

ONLY SUCH a device cooks odorously, the rest is illusions and self-hypnosis! yes, and the crappy welding seam of professional welders, whose seams are checked with ultrasound and x-rays, such inverters are infuriating.

make the accuracy of the welding current, say, 199201A, i.e. 0.

5% for any changes in the welding mode is given to selected and real specialists, and these will only be some Japanese and some American inverters, and only those that are not assembled by narrow-eyed idiots under a license, well, mine.

I’ll say right away that such a device does not weigh 3-7 kg, the trans weighs about 3 kg, the surge protector is another 3 kg, 2 output chokes are 4 kg, transistors with radiators are 1.5 kg, diodes on radiators are 2 kg, and what a case - the same thing weighs with the rest of the “small things”, in short, it adds up to 15-18 kg

The quality of welding depends on the welder. "smart", blah, statement! i.e., a good surgeon can perform an operation with minimal harm using an AXE? nah. . .needs a good scalpel? ! yeah, the body of the people has grown, but the brain remains virgin

A transformer welding machine will be more versatile because it can weld with both electrodes designed for alternating current and direct current. To improve the performance and quality of welding, a choke and some even a battery of capacitors (0.1-0.2 µF x 20 pcs or more) are added at the output to improve ignition and smooth out the current.

The advantages of a household inverter are obvious, so there is no need to even list them :-) If you want to get out of the situation, then your proposal will do.

answer

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Answers from experts

Schematic diagram of a bridge
rectifier for a welding machine, indicating polarity

To smooth out voltage ripples, one of the CA terminals is connected to the electrode holder through a T-shaped filter consisting of an inductor L1 and a capacitor C1. Choke L1 is a coil of 5070 turns of a copper bus with a tap from the middle with a cross-section of S = 50 mm2, wound on a core, for example, from a step-down transformer OCO-12, or more powerful.

The larger the cross-section of the iron of the smoothing choke, the less likely it is that its magnetic system will go into saturation. When the magnetic system enters saturation at high currents (for example, when cutting), the inductance of the inductor decreases abruptly and, accordingly, current smoothing will not occur. The arc will burn unsteadily.

Capacitor C1 is a battery of capacitors such as MBM, MBG or similar with a capacity of 350-400 μF for a voltage of at least 200 V

As practice shows, you should not choose the minimum values of S = 25..35 cm2, since the welding machine will not have the required power reserve and it will be difficult to obtain high-quality welding. And hence, as a consequence, the possibility of overheating of the device after short operation. To prevent this from happening, the cross-section of the welding machine core should be S=45..55 cm2. Although the welding machine will be somewhat heavier, it will work reliably!

Add a regular rectifier bridge, with high-current diodes, preferably with cooling, since diodes do not tolerate overheating well.

the main quality is constant, the metal transition is streamy, the change is drip, arc burning is more stable, etc.

It's much better on a permanent basis. These are inverters.

A DC welding machine is an AC welding machine plus a rectifier. Welding with direct current can be carried out both with electrodes designed for alternating current and with electrodes designed for direct current. For example, stainless steel can only be cooked using direct current.

All welding machines are different variations of this ratio, although inverter machines also add a frequency converter, which, with normal power, makes it possible to reduce the size of the machine.

A constant is a constant. The physics of the process is such that the current is transferred by electrons, so it is much easier, for example, to cut with direct current. If you change the polarity, it’s easier to cook it in general. By the way, you can get constant power not only with an inverter. To regular welding during recess

The rectifier will be permanently attached. The current just needs to be taken into account - it’s large, up to 200 Amperes.

Source: https://dom-voprosov.ru/prochee/kak-peredelat-svarochnyj-apparat-peremennogo-toka-na-postoyannyj