Homemade welding machine from an old electric motor. How to make a homemade welding machine from an electric motor

12.06.2019

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I will not explain how you can make money using a welding transformer. I think it’s clear to everyone: if you want, wind up transformers and sell them, or if you want, wind up one and have fun. Either at home or on call.

The idea of producing transformers from electric motor stators was practiced twenty years ago and was popular among DIYers. By the way, it brought in significant income. For 50-75 Soviet karbovanets one could get rid of such a product in one or two days. That's what I did. There were even publications on this topic in “Model Designer” and “Inventor and Innovator”.

A little later there were also publications about welding transformers from LATRs. And if there were no special problems with transformers from LATRs, then with those from engines, the results of homemade ones were very far from the calculated ones. And the reason for this is a lack of knowledge in electrical engineering, and magazines published material, hiding all the undercurrents.

It looked more like instructions to a young dushman, with recipes for landmines. All that was left was to shout: “Allahu Akbar” or “Banzai” and plug it into the socket. And then, at a minimum, burnt-out plugs, at a maximum - a kerdyk to the electric meter and a lot of flattering reviews addressed to the inventors and their parents.

Of course, I understood all the reasons for the failures, but I didn’t want to give away secrets so as not to breed competitors. And only after I found a more interesting income, in the form of electric fishing rods, did I begin to share information. I was still living in Samara at the time, and the opportunity to make money on fish attracted me much more than grunting and sweating over welders.

So, about transformers. First you need to choose the right electric motor. Of the most common series 2A and 4A, preference should be given to the first. They have bigger window Accordingly, it will be easier to wind the magnetic circuit. If you don’t find one, you can choose 4A. Only, to make work easier, it is better to divide the package of its magnetic circuit into two parts. Otherwise, the windings may not fit into the window. And then wind them separately and connect them in series.

For the manufacture of LATR, it is best to use an electric motor, which is not a pity. Rewinding electric motors can return them to work and they will continue to serve faithfully long term. Therefore, use those that definitely cannot be repaired.

Of the entire electric motor, only the magnetic circuit is used. Windings, rotor, stator housing - it all goes to waste. Therefore, the name “transformer from an electric motor” does not accurately reflect the essence.

So which engine should you choose? It is clear that the series is 2A, but what power? Guideline - from 7 to 15 kW. You won't miss.

Next, your task is to get the coveted stator. Nowadays they are easier to buy from scrap metal collectors. They are already cleared of wires and, as a rule, after 5-6 blows of the sledgehammer they crack like a nut. But this does not always happen. Engines that have undergone repairs are filled with varnish, so the housing may not separate from the iron package. And the body may turn out to be aluminum. In order to achieve the goal, you will have to anneal the entire stator. To do this, you need to put the stator “on its butt” and place a couple of bricks under it. The internal cavity is filled with firewood and set on fire. After frying your engine for an hour or two, you can easily separate the magnetic circuit from the housing. Iron falls out of aluminum casings during the roasting process. The wires are removed in the same way (if you come across a stator that has not been looted). After heat treatment, they are easily removed from the stator grooves.

As a result of your work, you should have a product as shown in Figure 1 (see below).

Package of transformer iron (magnetic core)

Rice. 1

Then you need to take the dimensions, as shown in Fig. 1. This blank must be impregnated with liquid oil varnish. And dry using heat. This must be done so that, after removing the tie strips, the bag does not fall apart. As a rule, there are four or more overlays. On powerful electric motors, they are also electrically welded on the sides.

It is necessary to remove not only the linings, but also the welded metal. This is done using a grinder, grinder or milling machine.

You may ask: why is this being done? The fact is that magnetic flux in a future transformer, will propagate differently than in an electric motor. And these pads will be short-circuited turns and, accordingly, take the lion's share of the power and cause heating. And here the main rule is the absence of short-circuited turns. They should not be present, either in the design of the transformer itself, or in its attachment to the housing.

The electromagnetic parameters of such iron are most often unknown, but they can be determined experimentally with sufficient accuracy.

After you get rid of the overlays and traces of electric welding, you will need to cut out two end overlays (see Fig. 2) and two cardboard sleeves from cardboard or pressboard. One for outside, another for internal. First, the end plates are installed, and then the outer and inner sleeves. Then the whole thing is wrapped in keeper, taffeta or glass tape and again impregnated with varnish and dried.

End insulator made of pressed spandex

Rice. 2

Now your toroidal magnetic circuit is ready to become a real transformer. The wire will need to be in cotton or glass-enamel insulation, or paper insulation is also possible.

To continue, we need to make calculations. For the primary winding, a wire with a diameter of 2-2.5 mm is sufficient; for the secondary winding, an 8 x 4 mm busbar with a length of about 60 m is suitable (depending on the iron). This is an option for copper. For aluminum, the cross-section needs to be 15% larger. Don't confuse section with diameter.

1) The number of turns per volt is calculated according to the formula:

48 / (a x b), where (a x b) is the area in square centimeters, not millimeters.

We select 210 V for the primary winding (it will drop under load). Number of turns for the primary winding:

210 x (value obtained from formula 1).

Starting from 180 V, it is necessary to make taps every 10 V: that is: 180 V, 190 V, 200 V. This will be useful to you in case of low voltage in the network. For the secondary winding V=55-65 V at Idling(condition for arc stability). The turns are calculated in the same way.

If you have a stator from a 4A motor, then the coefficient of 48 can be reduced to 46.

After completing the calculations, you can start winding. First primary, then secondary. You should wind it turn to turn, not in bulk. This will give higher inductance to the windings and optimize the operating mode of the transformer. You will need an assistant. Winding a tire onto a torus is a labor-intensive process, especially if you do not have a round shuttle. Therefore, you can simplify the process as follows. The tire must be launched into the torus, approximately half the length. And then wind from the middle to the end of the wire. First one part of the tire, then the other. Otherwise, your head will spin, running here and there. Conclusions should be fixed with tape.

Rice. 3

After the winding process is completed, the transformer should be varnished again. And dry thoroughly. You should pay special attention to this. It may happen that a transformer that is dry to the touch, when connected to the network, will begin to smoke at idle. This means he's kaput. The primary winding has closed. The fact is that under the influence of a strong magnetic field some solvents (included in the varnish) begin to conduct current. Even if you tested the varnish with a megohmmeter before use. Therefore, it is better to dry it hot, in a closet, or put it on a winding D.C., low voltage.

Transformer assembly

Rice. 4

If you do everything carefully, your machine will weld with electrode No. 4 and cut with electrode No. 3, working from a household outlet. The plugs on the meter should be set to 16A during operation. The device consumes about 10 A during operation. That is, the same as a Tefal kettle. On the “three” the transformer does not heat up at all, but on the “four” you need to burn about ten continuously so that it heats up to 50 degrees. This will be enough for you, both for yourself and for the coven. If you have a five-amp meter, then do not burn more than three or four electrodes No. 4 in a row.

I won’t talk about weight and other advantages. So much has been written about them that fairy tales are already appearing about their miraculous properties. It’s better to talk about where you can now get the wire for the transformer. Previously, all this was lying around in large heaps in the trash. Today the wire can be found where it is worked with. For us these are local power grids and locomotive depot. Double the price of this non-ferrous metal twice the price of scrap metal, and they will always pick up a burnt or broken coil from an oil transformer for you. In such a coil there is always a piece of a whole wire that goes into use. And if you except own hands If you have something in your wallet, you can order it at an electrical goods store. But the cost of such a product will be several times higher than that produced from scrap. Therefore, remembering Grandfather Marx, I recommend investing as little as possible :-)). And at the end of my life, write the book “How Steel Was Stealed” :-))))).

Often toroidal welding transformers are wound on a magnetic core taken from a failed large asynchronous three-phase electric motor. Asynchronous electric motors are the most common in industry and equipment among other types of motors. Motors with a power of approximately 4 kW or more are suitable for the manufacture of a welding transformer.

The design of an asynchronous electric motor is quite simple - it consists of a rotor rotating on a shaft and a stationary stator pressed into metal case electric motor. All this is connected by two side covers, tightened together with pins. It is very easy to disassemble it, just unscrew the nuts on the studs of the covers. IN in this case For us, only the stator is of interest.

The stator consists of a set of iron plates - a magnetic circuit round shape with windings installed on it. The shape of the stator magnetic circuit is not completely circular, with inside it has longitudinal grooves into which the motor windings are placed. U various brands engines even of the same power may have stators with different geometric dimensions. For the manufacture of transformers, those with a larger body diameter and correspondingly shorter length are better suited.

The most important part for us in the stator is the magnetic circuit ring; everything else just gets in the way. The magnetic core is pressed into a cast iron or aluminum motor housing. Wires that need to be removed are tightly packed into the grooves of the magnetic circuit. It is better to do this when the stator is still pressed into the housing. To do this, on one side of the stator, all the winding outputs of the former motor are cut off to the end with a sharp chisel. The wire should not be cut on the opposite side - there the windings will form something like loops through which the wires can be pulled out. Using a pry bar or a massive screwdriver, bend the wire loops and pull them out several wires at a time. The end of the engine housing serves as a stop, creating a lever. The wires come out easier if you burn them first. You can burn it with a blowtorch, directing the flame stream strictly along the groove. Here you need to be careful not to overheat the stator iron, otherwise it may lose its electrical properties. The cast iron body can then be easily destroyed - a few blows from a good hammer and it will crack - the main thing is not to overdo it. You can make two cuts along the body with a grinder or a hacksaw.

When removing the housing, you should immediately pay attention to the method of fastening the set of magnetic circuit plates. The plates can be fastened together into a single package, or they can simply be placed in a housing and clamped at the end with a lock washer. In the latter case, when the windings are removed and the housing is destroyed, the unfastened magnetic circuit will crumble into plates. To prevent this from happening, even before the body is completely destroyed, the package of plates must be fastened together. They can be pulled together with pins through the grooves. A set of magnetic circuit packages that are too large in area, which is typical for especially large engines, is also undesirable, since it is enormous weight. All excess iron must be separated before final assembly The magnetic circuit may be enough even for two transformers.

Sometimes you can hear that the remaining grooves of the windings must also be filled with transformer iron, supposedly to increase the area of the magnetic core. This must not be done under any circumstances: otherwise the properties of the transformer will deteriorate sharply, it will begin to consume exorbitant current, and its magnetic circuit will become very hot even in idle mode. Still, many people don’t like the grooved shape. And some recommend completely cutting out the projections of the grooves with a sharp chisel, while you need to work with glasses, and there should be no breakable objects nearby. Undoubtedly, after such an extremely complex operation, both the shape of the magnetic circuit will improve, and after removing useless elements, its weight will decrease. However, in general, the slots have little effect on the welding properties of the transformer - the welding characteristics remain good. For this reason, for the most part, no one touches these grooves.

If the ring of the motor magnetic circuit is already securely fastened and separated from the windings and the housing, then it is tightly insulated (with several layers of keeper tape), with special attention paid to sharp corners at the edges of the grooves. It is better to first place rings cut from hard dielectric material on the ends of the magnetic circuit to close the grooves and cover their sharp corners.

The stator ring has impressive dimensions - if the internal diameter is about 150 mm, then a wire of a significant cross-section can be laid in this one without worrying about the amount of space. Square cross section such a magnetic circuit periodically changes along the length of the ring due to the grooves; inside the groove its value is much less. It is this effective smaller value that should be used when calculating the number of turns of the primary winding.

The primary winding is wound around the entire insulated stator.

The primary winding is insulated with keeper tape.

The secondary winding is wound on top of the primary winding.

When winding the secondary winding of a toroidal transformer, it is advisable to lay it so that it does not overlap the last part of the primary, then the primary winding can always be wound or unwinded during final adjustment. Such a transformer can also be wound with windings spaced on different arms. In this case, you can always have access to each of them, but in this case there will be more power wasted.

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A little later there were also publications. And if there were no special problems with transformers from LATRs, then with those from engines, the results of homemade ones were very far from the calculated ones. And the reason for this is a lack of knowledge in electrical engineering, and magazines published material, hiding all the undercurrents.

So, about transformers. First you need to choose the right electric motor. Of the most common series 2A and 4A, preference should be given to the first. They have a larger magnetic circuit window, which means it will be easier to wind. If you don’t find one, you can choose 4A. Only, to make work easier, it is better to divide the package of its magnetic circuit into two parts. Otherwise, the windings may not fit into the window. And then wind them separately and connect them in series.

So which engine should you choose? It is clear that the series is 2A, but what power? Guideline - from 7 to 15 kW. You won't miss.

Next, your task is to get the coveted stator. Nowadays they are easier to buy from scrap metal collectors. They are already cleared of wires and, as a rule, after 5-6 blows of the sledgehammer they crack like a nut. But this does not always happen. Engines that have undergone repairs are filled with varnish, so the housing may not separate from the iron package. And the body may turn out to be aluminum. In order to achieve the goal, you will have to anneal the entire stator. To do this, you need to put the stator “on its butt” and place a couple of bricks under it. The internal cavity is filled with firewood and set on fire. After frying your engine for an hour or two, you can easily separate the magnetic circuit from the housing. Iron falls out of aluminum casings during the roasting process. The wires are also removed in the same way (if you come across a stator that has not been looted). After heat treatment, they are easily removed from the stator grooves.

As a result of your work, you should have a product as shown in Figure 1 (see below).

It is necessary to remove not only the linings, but also the welded metal. This is done using a grinder, a grinding machine or a milling machine.

You may ask: why is this being done? The fact is that the magnetic flux in the future transformer will propagate differently than in the electric motor. And these pads will be short-circuited turns and, accordingly, take the lion's share of the power and cause heating. And here the main rule is the absence of short-circuited turns. They should not be present, either in the design of the transformer itself, or in its attachment to the housing.

The electromagnetic parameters of such iron are most often unknown, but their.

After you get rid of the overlays and traces of electric welding, you will need to cut out two end overlays (see Fig. 2) and two cardboard sleeves from cardboard or a press. One for the outside, one for the inside. First, the end plates are installed, and then the outer and inner sleeves. Then the whole thing is wrapped in keeper, taffeta or glass tape and again impregnated with varnish and dried.

Now your toroidal magnetic circuit is ready to become a real transformer. The wire will need to be in cotton or glass-enamel insulation, or paper insulation is also possible.

The number of turns per volt is calculated using the formula:
48 / (a x b), where (a x b) is the area in square centimeters, not millimeters.

We select 210 V for the primary winding (it will go down under load). Number of turns for the primary winding:
210 x (value obtained from formula 1).

Starting from 180 V, it is necessary to make taps every 10 V: that is: 180 V, 190 V, 200 V. This will be useful to you in case of low voltage in the network. For the secondary winding V=55-65 V at no-load (condition for arc stability). The turns are calculated in the same way.

If you have a stator from a 4A motor, then the coefficient of 48 can be reduced to 46.

Once you have completed the calculations, you can start winding. First primary, then secondary. You should wind it turn to turn, not in bulk. This will give higher inductance to the windings and optimize the operating mode of the transformer. You will need an assistant. Winding a tire onto a torus is a labor-intensive process, especially if you do not have a round shuttle. Therefore, you can simplify the process as follows. The tire must be launched into the torus, approximately half the length. And then wind from the middle to the end of the wire. First one part of the tire, then the other. Otherwise, your head will spin, running here and there. Conclusions should be fixed with tape.

After the winding process is completed, the transformer should be varnished again. And dry thoroughly. You should pay special attention to this. It may happen that a transformer that is dry to the touch, when connected to the network, will begin to smoke at idle. This means he's kaput. The primary winding has closed. The fact is that under the influence of a strong magnetic field, some solvents (included in the varnish) begin to conduct current. Even if you tested the varnish with a megohmmeter before use. Therefore, it is better to dry it hot, in a closet, or apply low voltage direct current to the winding.

I won’t talk about weight and other advantages. So much has been written about them that fairy tales are already appearing about their miraculous properties. It’s better to talk about where you can now get the wire for the transformer. Previously, all this was lying around in large heaps in the trash. Today the wire can be found where it is worked with. For us, these are local power grids and a locomotive depot. Double the price of this non-ferrous metal twice the price of scrap metal, and they will always pick up a burnt or broken coil from an oil transformer for you. In such a coil there is always a piece of a whole wire that goes into use. And if you have something in your wallet besides your own hands, you can order it from an electrical goods store. But the cost of such a product will be several times higher than that produced from scrap. Therefore, remembering Grandfather Marx, I recommend investing as little as possible. And at the end of his life, write the book “How Steel Was Stealed”

The motor-transformer consists of an alternating current transformer, in which the magnetic circuit is made in the form of a ring with protrusions along the entire perimeter of the ring section and along the entire length of its circumference, and inside the magnetic circuit - ring, a non-magnetic rotor rotates, into the cylindrical surface of which magnets are recessed at the same distance. from each other, as well as the protrusions on the magnetic core-ring. At the ends of the non-magnetic rotor, protruding beyond the surface of the magnetic core-ring, non-magnetic disks and an external non-magnetic ring are fixed. In all of them internal surfaces The magnets are recessed with the same pitch as the protrusions on the magnetic core-ring. The step between the protrusions is equal to the movement of a point on the surface of the rotor as it rotates during one full period of alternating current. On the magnetic core-ring, in the spaces between the protrusions, the primary and secondary electrical windings are wound. The technical result is to increase torque. 1 ill.

The proposed invention relates to the electric power industry.

Currently, a transformer is used to convert alternating current from one voltage to another.

It is proposed to make the transformer magnetic circuit in the form of a ring with protrusions along the entire perimeter of the ring section and along the entire length of its circumference. A non-magnetic rotor rotates inside the magnetic core-ring, into the cylindrical surface of which magnets are recessed at the same distance from each other as the protrusions on the magnetic core-ring.

At the ends of the non-magnetic rotor, protruding beyond the surface of the magnetic core-ring, non-magnetic disks and an external non-magnetic ring are fixed. Magnets are recessed into all their internal surfaces with the same pitch as the protrusions on the magnetic ring-ring. The step between the protrusions is equal to the movement of a point on the surface of the rotor as it rotates during one full period of alternating current.

where T is the pitch between the protrusions,

D is the diameter of the protruding rotor magnets and the internal diameter of the protrusions of the magnetic circuit-ring,

N is the number of alternating current periods per second.

On the magnetic core - ring, in the spaces between the protrusions, the primary and secondary electrical windings are wound.

The drawing shows four designs for attaching magnets: straight and horseshoe-shaped.

1 - magnetic circuit-ring,

2 - rotating rotor.

It is necessary to spin a non-magnetic rotor with magnets built into it to a speed at which, in one full period of alternating current, one pole of the magnet moves from one protrusion of the magnetic ring-ring to another protrusion.

Then, during one half-cycle of alternating current, the protrusions of the magnetic core-ring attract the ends of the rotor magnets, and during another half-cycle of alternating current, they repel the same ends of the magnets. After this, it is necessary to apply alternating current to the primary winding. As a result, in the secondary winding we will receive an alternating current of the required voltage, and a rotating rotor with magnets will produce torque, which can be used for a variety of needs.

A motor-transformer containing a magnetic circuit in the form of a ring with protrusions located along the entire perimeter of the ring section, in the spaces between which two windings are wound, the primary, streamlined alternating current, and secondary - interacting with the poles of magnets of alternating polarity installed on the rotor, the distance between the poles of which is equal to the distance between the protrusions of the magnetic core, characterized in that the rotor is made with a non-magnetic body and is located inside the ring magnetic core and magnets are built into its cylindrical surface, and through the side Non-magnetic disks are attached to the rotor by an external non-magnetic ring with magnets built into all of their internal surfaces, which interact during rotation with the protrusions of the magnetic circuit carrying the windings.

But if you don’t know the easiest way to do this, then you can take a closer look at this project. Here welding transformer assembled from the engine stator. The good thing about the design is that the engine already has almost everything needed to create welding; you just need to make some modifications to the magnetic circuit and wind the transformer correctly.

Concerning technical characteristics, then asynchronous motors with a power of about 4 kW are suitable for such purposes; they are often used in various enterprises.

Materials and tools for homemade:
- electric motor with a power of 4 kW;
- wrenches, pliers, chisels, screwdrivers and other tools to disassemble the engine;
- keeper tape;
- sledgehammer.

Electric welding manufacturing process:

Step one. We disassemble the electric motor
According to the author, such an engine can be disassembled quite easily. You just need to stock up wrenches. Using them, you need to unscrew a pair of nuts that tighten the two motor covers to each other and the stator housing. If the engine is already rusty, then sometimes it is not so easy to unscrew these nuts; in this case, you can use a grinder and simply cut the studs. Well, after that you will need to use a hammer or sledgehammer to knock the covers off the engine.

After disassembly, you will need to remove the rotor from the stator; it will not be needed for homemade work. The stator is a set of steel plates; they form a magnetic circuit. There is a winding on the magnetic core. The stator dimensions of motors, as well as geometry, may differ. To create electric welding, it is best to choose motors with a large body diameter and a short length.

The greatest value in the stator is the magnetic circuit ring; everything else will only get in the way. The magnetic core is usually pressed into a cast iron or aluminum housing. Wires pass through the grooves of the magnetic circuit; they need to be removed. This is best done when the magnetic core is still in the housing. To remove the wires, you need to take a chisel and cut them off at the end using a sharp chisel on one side of the stator. Well, then you can pull them out in the form of loops using pliers, after prying them off with a screwdriver.
To make it easier to remove the wires, they can be burned using blowtorch. Just do not heat the metal of the magnetic core too much, otherwise it may lose its technical characteristics.

The cast iron body can be split using a sledgehammer. To ensure that it splits properly, longitudinal cuts can be made along it. But in this matter it is important not to overdo it, otherwise you can bend the magnetic circuit.

Step two. Preparing the magnetic circuit
After the housing is removed, you need to carefully inspect the magnetic circuit to determine how it is fastened. It happens that the plates are simply placed in the housing and secured with a lock washer. If this is the case, then such a structure may crumble during operation; it is best to tighten it with pins or fasten it in some other way in an accessible way. And sometimes the design is made in the form of a ready-made package. If the magnetic circuit package is too large, it can be reduced, since welding machine will be too heavy. If the engine is large, then it is quite possible that even two electric welds can be made from it.

As for the grooves of the magnetic circuit, there are several opinions. Some clog the grooves with transformer iron, but our author does not recommend doing this, as this greatly reduces the efficiency and increases the current consumption. What can be done is to completely cut off the grooves using a chisel. The good thing is that the transformer will become lighter. But since this procedure is quite painstaking, most people do not touch these grooves at all.

Step three. Insulation and winding
When the magnetic circuit is already prepared, you will need a keeper tape, with the help of which the housing must be carefully insulated by winding several layers. Special attention Pay attention to the sharp edges on the grooves, as this can easily penetrate the insulation. To avoid such problems, it is best to first put some kind of dielectric material on the sharp edges, and then wrap the magnetic circuit with tape.

After this, you can begin winding the primary winding. Since the diameter of the stator ring is about 150 mm, it is possible to lay the wire in it quite big size without worrying about running out of space. Due to the fact that the magnetic core has grooves, the cross-sectional area here will gradually change; inside the groove this value is the smallest. The number of turns must be calculated based on this smallest effective value.

The author winds the primary winding directly around the entire magnetic circuit ring. Then the whole thing is again insulated from above using keeper tape.

Well, the secondary winding is wound on top of the primary. So that the transformer can be adjusted if necessary, the secondary winding must be wound so that it does not overlap the ends of the primary. Then it can be rewinded or rewinded if necessary.

If necessary, the transformer coil can be separated into two arms. Then each shoulder can be accessed at any time. But with this design, welding will lose power. As for the technical characteristics of such a homemade product, welding can be done without problems with a 4 mm electrode if it is done correctly, and cut with a 3 mm electrode. And all this from a regular outlet.
This unit consumes up to 10A when operating. You can cook with a 3 mm electrode for as long as you like, the transformer does not heat up. And if you burn ten pieces by 4 mm, the transformer will heat up to about 50 degrees.

Winding calculation
For the primary winding you will need a wire with a diameter of approximately 2-2.5 mm. The secondary winding is made from a busbar measuring 8x4 mm, this applies to copper, for aluminum the cross-section should be 15 percent larger.
To calculate the number of turns, the formula is used: 48 / (a x b), where (a x b) is the area in square millimeters.

The voltage for the primary winding should be chosen 210V, since it drops under load. After the value of 180V is reached, taps will need to be made every 10V. They will be needed if welding needs to be used in a place with low voltage.
As for the secondary winding, for a stable arc at idle it should produce 55-65V.

Homemade welding machine from an old electric motor. How to make a homemade welding machine from an electric motor

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