Homemade spot welding machine. Description of the process of self-assembly of spot welding. Electrodes for homemade spot welding

The easiest to manufacture are AC resistance spot welding machines with unregulated current. The welding process is controlled by changing the duration of the electrical pulse - using a time relay or manually using a switch.

Before considering the designs of homemade devices for resistance spot welding, we should recall the Lenz-Joule law: when an electric current passes through a conductor, the amount of heat generated in the conductor is directly proportional to the square of the current, the resistance of the conductor and the time during which the electric current flowed through the conductor ( Q=I 2 R t). This means that at 1000A current, about 10,000 times more energy is lost on poorly made connections and thin wires than at 10A current. Therefore, the quality of the electrical circuit cannot be neglected.

Transformer. The main component of any resistance spot welding equipment is power transformer with a high transformation ratio (to provide high welding current). Such a transformer can be made from a transformer from a powerful microwave oven (the power of the transformer should be about 1 kW or higher) feeding the magnetron.

These transformers are distinguished by their availability and high power. Such a transformer is enough for a precision welding machine capable of welding steel sheets 1 mm thick. If you need a more powerful spot welding machine, you can use two (or more) transformers (how to organize this is described below).

In a microwave oven, the magnetron requires a very high voltage (about 4000V) to operate. Therefore, the transformer feeding the magnetron does not step down, but increases. Its primary winding has fewer turns than the secondary, and the thickness of the winding wire is greater.

The output of such transformers is up to 2000V (a double voltage is supplied to the magnetron), so you should not check the performance of the transformer by connecting it to the network and measuring the voltage at the output.

Such a transformer requires a magnetic core and a primary winding (the one with fewer turns and a thicker wire). The secondary winding is cut off with a hacksaw or chopped off with a chisel (if the magnetic core is securely welded and not glued), knocked out with a rod or drilled out and picked out. The need for drilling arises when the winding is packed very tightly into the window and an attempt to knock it out can lead to destruction of the magnetic circuit.

When removing the secondary winding, care must be taken not to damage the primary winding.

In addition to two windings, shunts that limit the current can be built into the transformer; they must also be removed.

After removing unnecessary elements from the transformer, a new secondary winding is wound. To provide a large current close to 1000A, a thick copper wire with a cross-sectional area of ​​more than 100 mm 2 (wire with a diameter of more than 1 cm) is required. This can be either a single stranded wire or a bundle of several wires of small diameter. If the wire insulation is thick and prevents you from making a sufficient number of turns, then it can be removed and the wire wrapped with fabric insulating tape. The length of the wire should be as short as possible so as not to create additional resistance.

2-3 turns are made. The output should be about 2V, this will be enough. If you manage to cram more turns into the transformer windows, then the output voltage will be greater, therefore the current will be longer (in comparison with fewer turns of wire of the same diameter) and the power of the device.

If there are two identical transformers, then they can be combined into one, more powerful current source. This may be required when there are two transformers with insufficient power or when you want to make your own spot welding machine to work with thicker metal.

For example, in the case of insufficiently powerful transformers, each of the 0.5 kW transformers has an input voltage of 220V, the output voltage is 2V at nominal current 250A (the value is taken as an example, let the short-term welding current be 500A). Connecting namesake conclusions of the primary and secondary windings, we get a device in which, at the same voltage value (2V) nominal the output current value will be 500A (the welding current will almost double, and there will be more losses due to resistances).

At the same time, the connections in the circuit of secondary windings shown in the diagram must be on electrodes, that is, in the case of two transformers with a power of 0.5 kW there will be two identical wires with a diameter of 1 cm, the ends of which are connected to the electrodes.

If you make a mistake in connecting the terminals of the primary or secondary windings, there will be a short circuit.

If there are two sufficiently powerful transformers and you need to increase the voltage, and the dimensions of the magnetic circuit window do not allow you to make the required number of turns with a thick wire on one transformer, then the secondary windings of the two transformers are connected in series (one wire is pulled through two transformers), with the same number of turns on each transformer . The direction of the turns must be consistent so that there is no antiphase and, as a result, the output voltage is close to zero (you can experiment with thin wires first).

Typically, in transformers, winding terminals of the same name are always marked. If for some reason they are unknown, then they can be determined by performing a simple experiment, the diagram of which is shown below.

Here, the input voltage is supplied to the series-connected primary windings of two identical transformers, and an alternating voltage voltmeter is connected at the output formed by the series connection of the secondary windings. Depending on the direction in which the windings are turned on, there can be two cases: the voltmeter shows some voltage or the output voltage is zero. The first case indicates that in both the primary and secondary circuits the opposite terminals of the corresponding windings are interconnected. In fact, the voltage on each of the primary windings is equal to half the input and is transformed in the secondary windings with the same transformation ratios. When the secondary windings are turned on as indicated, the voltages on them are summed up and the voltmeter gives twice the voltage value of each winding. A zero voltmeter reading indicates that equal voltages on the secondary windings of transformers connected in series have opposite signs and, therefore, any pair of windings is connected by terminals of the same name. In this case, by changing, for example, the sequence of connecting the terminals of the primary windings as shown in Figure (b), we will obtain at the output twice the value of the output voltage of each of the secondary windings and we can assume that the windings of the transformer are connected different names conclusions. Obviously, the same result can be obtained by changing the sequence of connecting the terminals of the secondary windings.

To make a more powerful spot welding machine with your own hands, you can connect more transformers in the same way, if only the network allows it. A transformer that is too powerful will cause a large voltage drop in the network, causing fuses to trip, light bulbs to flicker, neighbors to complain, etc. Therefore, the power of homemade spot welding machines is usually limited to values ​​that provide a welding current of 1000-2000A. The lack of current is compensated by increasing the welding cycle time.

Electrodes. Copper rods (rods) are used as electrodes. The thicker the electrode, the better; it is desirable that the diameter of the electrode is not less than the diameter of the wire. Tips from powerful soldering irons are suitable for low-power devices.

The electrodes must be sharpened periodically, because they lose their shape. Over time, they wear down completely and require replacement.

As already written, the length of the wire running from the transformer to the electrodes should be minimal. There should also be a minimum of connections, because There is a loss of power on every connection. Ideally, copper lugs are placed on both ends of the wire, through which the wire is connected to the electrodes.

The tips must be soldered to the wire (the wire cores must also be soldered). The fact is that over time (possibly at the very first start), oxidation of copper occurs at the contacts, leading to an increase in resistance and a large loss of power, which is why the device may stop welding. Plus, when crimping tips, the contact area is smaller than when soldering, which also increases the contact resistance.

Due to the large diameter of the wire and tip for it, it is not easy to solder them, but sold tin-plated solder tips can make this task easier.

Unsoldered connections between tips and electrodes also create additional resistance and oxidize, but since The electrodes must be removable; it is inconvenient to unsolder the old ones and solder in the new ones each time you replace them. Moreover, this connection is much easier to clean from oxides than the end of a stranded wire crimped with a ferrule.

Controls. The only controls may be a lever and a switch.

The compression force between the electrodes must be sufficient to ensure contact of the parts being welded with the electrodes, and the thicker the sheets being welded, the greater the compression force must be. On industrial devices, this force is measured in tens and hundreds of kilograms, so the lever should be made longer and stronger, and the base of the device should be more massive and can be attached to the table with clamps.

A large clamping force for homemade spot welding machines can be created not only with a lever clamp, but also with a lever-screw clamp (a screw tie between the lever and the base). Other methods are possible, requiring different equipment.

The switch must be installed in the primary winding circuit, because there is a very large current in the secondary winding circuit and the switch will create additional resistance, in addition, the contacts in a regular switch can be tightly welded.

In the case of a lever clamping mechanism, the switch should be mounted on the lever, then with one hand you can press the lever and turn on the current. The second hand will remain free to hold the parts being welded.

Exploitation. It is necessary to turn the welding current on and off only when the electrodes are compressed, otherwise intense sparking occurs, leading to burning of the electrodes.

It is advisable to use forced cooling of the device using a fan. In the absence of the latter, you need to constantly monitor the temperature of the transformer, conductors, electrodes and take breaks to prevent them from overheating.

The quality of welding depends on the experience gained, which comes down mainly to maintaining the required duration of the current pulse based on visual observation (by color) of the weld point. More information about performing spot welding is written in the article Contact spot welding.

Video:

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Do-it-yourself spot welding will be of interest to those who need a welding machine, but who do not want to spend a lot of money on it.

In this case, resistance spot welding is the best option, because You can assemble such a device literally from available materials.

In the article you will learn about how to assemble the device at home, what tools and equipment will be required for this, as well as the pros and cons of this type of welding.

The diagram and video will help you complete the entire process yourself and get a high-quality product that will last for many years.

How does this type of welding work?

Spot welding is not at all an amateurish type of work, which is used only for home use - it is widespread both in industrial scale, and in private production.

Spot welding is contact work to connect two elements in the desired position. This type of welding is similar to seam and analogue, but still has its differences and nuances.

The most significant advantage of spot welding is that any person more or less familiar with electrical engineering can make a machine for it (including from old microwave parts).

In addition, such a device will be in no way inferior to machines produced at a factory - the difference is that a home device can only be used on a local scale, but for personal needs you don’t need more.

If resistance welding is a new process for you, then it is better to first delve a little into this process and understand how the machine works. In this case, it will be much easier to assemble it.

Welding of elements occurs as follows: first you need to fix the metal parts in the position you need and place them between the electrodes of the device.

The parts are then heated until they become pliable and are then joined together.

The parts are heated by a pulse of electricity, the duration of which is no more than 1 second.

Its task is to melt parts of the parts and make, at the place where it is directed, something like a liquid bath, the diameter of which is 12 mm.

After the pulse has completed, the parts should remain fixed in the desired position for some time in order to have time to cool down and better connect with each other.

The advantages of spot welding are obvious: it low price for the production of the device itself (it is assembled practically from improvised means and with your own hands), significant savings in electricity, high strength of seams and automation of the process (production uses devices capable of producing up to 600 points/min).

This type of welding has only one drawback - you will not be able to make a sealed seam, although the resulting options will be quite strong and durable.

The welding diagram will help you better understand how it works.

As can be seen from the work process, the main task apparatus - heating parts to the melting point.

The heating power of different devices differs and you need to know what power and duration you need.

For example, for stainless steel it is better to use short heating, and for carbon steel - vice versa.

In addition, the welding machine must provide significant pressure on the parts being joined, the peak of which is reached at the end of heating. Without this, a high-quality connection of parts will not work.

Good spot welding electrodes imply high thermal and electrical conductivity and do not have problems with mechanical processing, so not every material is suitable for manufacturing.

You can use: bronze with an admixture of cobalt or cadmium, electrolytic copper and alloys based on it with tungsten and chromium.

To assemble the device with your own hands, it is best to use EV grade copper alloys.

During manufacturing, it is important to remember that the diameter of the thinnest element of the apparatus should not exceed the size of the melting point (its diameter should be 2-3 times smaller).

Watch a video on how to use spot welding for home use.

Stages of creation

As already mentioned, do-it-yourself spot welding can be assembled literally from available materials.

You need to start work by assembling the inverter. The use of an inverter will make the operation of the entire device possible.

To assemble it, use parts made in the USSR:

• diodes;
• capacitors;
• chokes;
• transformers.

In the case of using these parts, difficult additional customization not required.

Most often, the device is made from parts of an old microwave, which you may have in your home or at someone you know. This spot welding from old microwave parts has a power of about 800 Amps.

It is enough to weld fairly thin sheets of metal. As a rule, for home use more power is not needed.

Try to choose large rather than small microwaves, because... larger models have a more powerful transformer, which will be the basis of your welding machine.

The transformer looks like this: it is a core with two windings, the first of which is made of thick wire with fewer turns.

The transformer is held together by welds, so to get to its windings, you need to remove them (this can be done with a hacksaw or grinder).

The removed transformer must contain an intact winding and a core divided into 2 parts, cleaned of paper and glue that fixed the windings.

The transformer needs to be attached to the base, this can be done with epoxy resin - to do this, squeeze the mechanism with a vice and leave for a while so that the material can stick together.

The video below shows welding on a microwave transformer.

Thanks to the secondary winding, the power of the transformer will be approximately 2 W.

If you want the power of the device to be higher, then you will need another transformer from the microwave, which will need to be connected to the first one.

This is what the transformer circuit looks like.

When both windings of the device are connected, you need to check the current strength.

It should not be higher than 2000 Amperes, otherwise significant power surges are possible not only in your apartment, but also in all neighbors.

You can connect the transformer using the secondary winding.

In this case, the amount of welding current will double - if it was 220, it will become about 500.

For connection, use wires with a diameter of 10 mm. The connection diagram will help you do everything correctly, but if the technology is broken, then there is a high probability of a short circuit.

The voltage will go out to the first winding, and at the output you need to turn on a voltmeter that can work with alternating voltage.

You need to choose the direction of operation of the windings based on the following options: there is voltage in the device or there is no voltage.

In the primary circuit one can observe the presence of windings with opposite terminals.

The voltage of these windings is usually equal to ½ of the input voltage, its increase and transformation will occur in the windings following this one, but the coefficients will be the same.

Below is a diagram of how to make a spot welding gun.

After turning on the secondary windings, you need to add up the difference in the resulting potentials - then the voltmeter will show twice the difference for each of the windings.

If the device shows “0”, then the resulting values ​​will be equal, but with opposite signs.

Therefore, each connected pair of windings will have similar terminals.

Watch the video on how to properly remove and reassemble a spot welding transformer.

Transformer pliers

For the device to work, you need not only a transformer, but also pliers. The pliers are a mechanical part of the machine.

Therefore, spot welding necessarily requires the making of pliers and electrodes, without which the operation of the device is impossible.

To make pliers, you need to sharpen the rods of the electrodes that you will use, because... otherwise they will become deformed. Electrodes cannot work forever and lose their properties over time.

The wire that connects the electrodes and the current transducer does not need to be long, otherwise it will be inconvenient to work. Also there should not be many connections, because... each of them will take power.

It is best to make copper lugs at the ends of the wire, which can connect the electrodes to the wire.

The tips are soldered so that the fit is as tight as possible, because a poorly soldered connection will cause a significant loss of power of the device and even its breakdown.

Soldering the tip and wire with your own hands will not be so easy due to the significant diameter, so when working, use solder tips, they will make the work easier.

This will also help when it comes time to replace the electrodes, because... Replacing old rods with new ones is not very convenient.

A connection made using a solder tip is easier to remove oxidized areas from.

Electrodes can be purchased at any market with electrical appliances. They look like small rods (diameter slightly more than 1 cm). The electrode diagram is below in the photo.

If the microwave transformer has poor welding, you can use electrodes from soldering irons - to do this, you need to remove the tips from them.

Connect the electrodes with a short cord without unnecessary connections.

To make the connection between the electrode and the transformer, make a hole with a drill or drill, but you can also use a copper tip.

To secure it tightly, tighten the bolt as much as possible, and to avoid the oxidation process, solder the wire to the tip.

Spot welding machines are not used as often in everyday life as arc welding machines, but sometimes it is impossible to do without them. Considering that the cost of such equipment starts from $450-$470, the profitability of its purchase is questionable.

The way out of this situation is resistance spot welding with your own hands. But, before we tell you how to make such a device yourself, let's look at what spot welding is and the technology of its operation.

Briefly about spot welding

This type of welding is contact (thermomechanical). Note that this category also includes seam and butt welding, but it is not possible to implement them at home, since complex equipment will be needed for this purpose.

The welding process includes the following steps:

• the parts are combined in the required position;
• they are secured between the electrodes of the device, which press the parts;
• heating is performed, as a result of which, due to plastic deformation, the parts are firmly connected to each other.

A production spot welding machine (such as the one shown in the photo) is capable of performing up to 600 operations within a minute.

Process technology

To heat the parts to the required temperature, a short-term pulse of high-power electric current is applied to them. As a rule, the pulse lasts from 0.01 to 0.1 seconds (the time is selected based on the characteristics of the metal from which the parts are made).

When pulsed, the metal melts and a common liquid core forms between the parts; until it hardens, the welded surfaces must be held under pressure. Due to this, as it cools, the molten core crystallizes. A drawing illustrating the welding process is shown below.

Designations:

• A – electrodes;
• B – parts to be welded;
• C – welding core.

Pressure on the parts is necessary so that, when pulsed, a sealing belt is formed along the perimeter of the molten metal core, preventing the melt from flowing outside the zone where welding occurs.

To provide Better conditions To crystallize the melt, the pressure on the parts is gradually removed. If it is necessary to “forge” the welding site in order to eliminate inhomogeneities inside the seam, increase the pressure (do this at the final stage).

Please note that to ensure a reliable connection, as well as the quality of the seam, it is first necessary to treat the surfaces of the parts in the places where welding will take place. This is done to remove oxide film or corrosion.

When it is necessary to ensure reliable connection of parts with a thickness of 1 to 1.5 mm, capacitor welding is used. The principle of its operation is as follows:

• the capacitor block is charged with a small electric current;
• the capacitors are discharged through the parts being connected (the pulse strength is sufficient to ensure the required welding mode).

This type of welding is used in those areas of industry where it is necessary to connect miniature and subminiature components (radio engineering, electronics, etc.).

Speaking about spot welding technology, it should be noted that it can be used to connect dissimilar metals together.

Examples of homemade designs

There are many examples on the Internet of creating machines that produce spot welding. Here are some of the most successful designs. Below is a diagram of a simple spot welder.

For implementation we will need the following radio components:

• R - variable resistance with a nominal value of 100 Ohms;
• C – capacitor designed for a voltage of at least 25 V with a capacity of 1000 μF;
• VD1 – thyristor KU202, the letter index can be K, L, M or N, you can also use PTL-50, but in this case the capacitance “C” must be reduced to 1000 μF;
• VD2-VD5 – diodes D232A, foreign analog – S4M;
• VD6-VD9 – D226B diodes, they can be replaced with a foreign analogue 1N4007;
• F – 5 A fuse.

It is necessary to make a digression to tell how to make the TR1 transformer. It is made on the basis of Sh40 iron, with a set thickness of 70 mm. For the primary winding you will need PEV2 wire Ø0.8 mm. The number of turns in the winding is 300.

To make a secondary winding, you will need a Ø4 mm stranded copper wire. It can be replaced with a tire, provided that its cross-section is at least 20 mm 2. The number of turns of the secondary winding is 10.

Video: do-it-yourself resistance welding

As for TR2, any of the low-power transformers (from 5 to 10 W) will be suitable for it. In this case, winding II, used to connect the backlight lamp “H”, should have an output voltage within 5-6 V, and winding III – 15 V.

The power of the manufactured device will be relatively low, ranging from 300 to 500 A, maximum pulse time up to 0.1 sec (provided that the ratings “R” and “C” are the same as in the diagram shown). This is quite enough for welding steel wireØ0.3 mm or sheet metal if its thickness does not exceed 0.2 mm.

Let us present a diagram of a more powerful device, in which the welding electric current of the pulse will be in the range from 1.5 kA to 2 kA.

We list the components used in the circuit:

• resistance ratings: R1-1.0 kOhm, R2-4.7 kOhm, R3-1.1 kOhm;
• capacitances in the circuit: C1-1.0 µF, C2-0.25 µF. Moreover, C1 must be designed for a voltage of at least 630 V;
• VD1-VD4 diodes - D226B diodes, replacement with a foreign analogue 1N4007 is allowed, instead of diodes you can install a diode bridge, for example, KTs405A;
• thyristor VD6 - KU202N, it must be placed on a radiator with an area of ​​at least 8 cm2;
• VD6 – D237B;
• F - 10 A fuse;
• K1 is any magnetic starter that has three pairs of working contacts, and the winding is designed for ~220 V, for example, you can install PME071 MVUHLZ AC3.

Now we’ll tell you how to make transformer TR1. The LATR-9 autotransformer, such as shown in the photograph, is used as a basis.

The winding in this autotransformer has 266 turns, it is made with copper wire Ø1.0 mm, we will use it as the primary. We carefully disassemble the structure so as not to damage the winding. We dismantle the shaft and the movable roller contact attached to it.

Next, we need to isolate the contact track; for this purpose, we clean it from dust, degrease it and varnish it. When it dries further, we insulate the entire winding using varnished cloth.

As a secondary winding we use copper wire with a cross-sectional area of ​​at least 80 mm 2. It is important that the insulation of this wire is heat resistant. When all conditions are met, we make a winding of three turns.

Setting up the assembled device comes down to calibrating the scale of the variable resistor that regulates the pulse time.

We recommend that before starting welding, you experimentally establish the optimal time for the pulse. If the duration is excessive, the parts will be burned, and if it is less than necessary, the strength of the connection will be unreliable.

As already written above, the device is capable of delivering a welding electric current of up to 2000 A, which allows you to weld steel wire Ø3 mm or sheet steel, the thickness of which does not exceed 1.1 mm.

Sooner or later, many people have a desire to purchase their own welding machine. But, unfortunately, such equipment is highly expensive, so many people prioritize making a homemade device. With the help of freely available diagrams, drawings and other step-by-step guidance for the upcoming event can become very simple and understandable.

Description and principle of operation

Currently, resistance spot welding is in great demand and is used in a wide variety of human activities. The tool is indispensable when repairing or producing metal parts. It can also be used for the manufacture of metal stairs, gates, individual structural elements and other details.

The operating principle of resistance welding is as follows: the electric current present in the key unit is capable of heating individual parts of a steel workpiece that are connected to each other. In this way, a special welded joint- seam The quality of the result is determined by the type of material from which the product is made, as well as the density. In addition, when carrying out welding activities attention should be paid for the following features:

1. The welding circuit must have low voltage levels - from 1 to 10 watts.
2. The welding process continues for several seconds.
3. The welding pulse is characterized by great strength current.
4. The smaller the melting zone, the higher the welding quality.
5. The weld must cope and withstand heavy loads.

Correct adherence to such rules depends on final result of welding activities. Making a device with your own hands is quite difficult. In order for the task to be completed successfully, it is necessary to precisely learn a number of specific instructions and technological recommendations.

A simpler solution is to assemble a welding machine with variable current. Such a device is capable of controlling the welding process by changing the duration of the welding pulse that hits the workpiece. In addition, in order to successfully complete the task, it is necessary to equip a clock relay, which can be controlled automatically or manually.

Important design properties

Key unit of the welding device The spot type is a welding transformer that is often found in microwave ovens, televisions and other equipment. Rewinding of the winding is carried out only after determining the ratio of the required current and voltage, during the supply of which welding occurs.

To select the appropriate device control option, you must correctly assemble the main mechanisms. It is no secret that structural parts are selected taking into account the power and parameters of the transformer.

When manufacturing resistance welding systems, it is taken into account relationship between type of application and material properties, which can be processed. In most cases, welding pliers are attached to the main device.

Doing any assembly work, be extremely attentive and thorough. Build quality must be maximum, otherwise further operation may become problematic. Wires are selected with the appropriate diameter and cross-section. If the circuit reliability is not good enough, the intensity of the required electric current will not be stable. In addition, there is an increased risk of sparks causing workers to stop welding.

Spot welding diagram

To make your own spot resistance welding, carefully study the corresponding diagrams. The most popular of them effective in situations where metal sheets have to be processed with a thickness of one millimeter or wiring and rod with a diameter of up to 4 millimeters.

In this case, it is necessary to take into account the following features:

1. For welding, you should acquire equipment with an alternating voltage of 220 W.
2. As for the output voltage type when idling, it is 3-7 V.
3. The maximum welding current reaches 1.5 thousand amperes.

The entire structure is characterized circuit diagram, which consists of power parts, an automated switch and a control circuit. If dangerous situations arise while performing a task, all you have to do to prevent them is press the switch. At the first node there is a transformer for welding T2 and a device for a contactless thyristor switch of a single-phase type, which connects the primary winding to the electrical power source.

As for the second scheme, it requires the implementation of a characteristic winding on the welding transformer using certain turns. On the primary winding there are lead-out sections, which are intended to adjust the output welding current taking into account the ratio of the secondary winding. Thus, the permanent connection of the network circuit remains at the first pin, and the operation of the power supply is regulated through the others.

Important detail of the system marked M TT4 K is distinguished by serial production. This module contains a thyristor switch that switches the load through contacts 1 and 3. The device can operate under loads with voltages up to 800 watts and currents up to 80 amperes. The composition of the scheme includes:

1. power unit.
2. chain for setting the mechanism.
3. relay k1.

Any transformer system with a power of up to 20 watts is used as a source of electrical power for welding equipment. At the same time, it is used when operating on a nominal network of 220 V. As for the voltage that is supplied on the second version of the winding, its indicators reach 22 V. To rectify the intensity of the current supply, you can install a diode bridge. The option of using any other nodes with similar parameters is also not excluded.

Device features and design

Currently, there are several functions of the control circuit. If you need to turn on k1 for a given period of time, you need to correctly set this period by determining exact time supplying electronic pulses to the elements being welded.

The electrical circuit design contains capacitors: from c1 to c6 with characteristic electrolytic properties. Their voltage is 52 V. In addition, you need to use a capacitor with a capacity of 46 μF.

The main power unit of the mechanism is the transformer. It acts as a converter from one type of electricity to another. In this case, it is customary to use a 2.5 A magnetic wire. It is better not to use the old winding, but to install electric cardboard rings at the end of the magnetic wire. They are folded along the inner and upper edges. The next step is to wind the magnetic circuit with lattic fabric in three or more layers. To successfully complete the winding, you should use the following wires:

1. primary winding with a diameter of 1.5 millimeters, which is impregnated with a varnish composition.
2. the second version of the winding with a diameter of about two centimeters, which is equipped with multi-core insulation of organosilicon origin.

When making the first winding, it is important to arrange intermediate type terminals. Then the winding is impregnated with a special varnish, and the primary coil is wound cotton tape, which is also impregnated with a varnish composition. Then the process of secondary winding begins, as well as further impregnation with varnish.

Manufacturing pliers for welding equipment

If you want to make homemade spot welding, you must take a responsible approach to the design of the pliers. Today, two types of such elements are used:

1. stationary.
2. remote

The first solution is characterized by ease of operation, as well as high-quality and reliable insulation, which is due to firmly connected node sections. True, such pliers are characterized by one drawback - in order to provide clamping force, you need to apply physical force.

The version of external pliers is particularly easy to use and compact in size. To control the efforts of the pliers, it is enough to change the length of their extension behind the device. Bolts, bushings and washers are installed at the connections of such parts for more reliable waterproofing.

When making parts It is customary to use copper rods or beryllium bronze. You can also use a tip from a soldering machine with high performance power. As for the diameter of the electrode, it must match the diameter of the wire to which it is connected.

So that the welding cores have good quality, the ends of the electrodes are narrowed and made small.

Microwave spot welding

It's no secret that purchased models are very expensive, so it makes sense to give preference to homemade solutions. To make a productive installation, you can use a large microwave oven. It is the dimensions that determine the power of the future device..

If you don't have a microwave, try looking for one at a flea market or buying one from your neighbors. Such a purchase will not be a big investment. In the future, all that remains is to disassemble the microwave and remove the high-voltage transformer from it.

Be careful, because even in a disassembled state without direct connection to electrical network individual components of equipment can “beat” with current.

The main parts of the transformer are represented by a core and two types of winding - primary and secondary. To connect the core, you can use two thin welds. Get rid of them in advance, which can be done with a hammer and a hacksaw. You can also use a grinder, which will allow you to get to the transformer windings without damaging them. To remove the secondary winding, just cut the secondary with careful movements.

Ultimately, you will have access to the core from the transformer, which consists of two parts.

The next step is to carry out the secondary winding of the transformer part. Here you will need to use a copper cable with the same cross-section as the transformer slot. It is necessary to wind about two turns. Using standard two-part epoxy resin, join the two halves of the core together. To make the process especially successful, try fixing them in a vice.

Don't forget to check the voltage level at the output of the transformer mechanism. It should not exceed the 2 volt mark. In this case, the minimum current value varies within 850 A.

Then you need to start manufacturing the body of the welding material. On at this stage You can use wood or high-strength plastic. There are several holes on the back panel. One of them is responsible for the electrical supply, and the second is for turning the system on and off.

Conclusion

If the body part is dry, you can proceed to assembling the device by connecting the working units together. Then you need to cut two pieces of copper wire with a size of about 25 millimeters. They act as electrodes, which are fixed in the holder using a regular screwdriver. Then you need to secure the switch with a thick cable, which will prevent it from falling out. The transformer is fixed using ordinary self-tapping screws. It is also important to take care of the grounding, which is fixed to one of the terminals.

If you carefully follow all the recommendations and step-by-step instructions, the process of assembling the welding machine will be successful. In this case, you can reduce all costs, depriving yourself of the need to buy expensive professional equipment.

Welding plays an important role in technical processes. One of its types, spot welding, is the joining of parts together at one or more points. A spot welding machine can significantly reduce the final cost and reduce production time, especially if made by yourself.

Welding Strength

The strength of the weld is affected by the size and material of the area. And it is affected by:

• Electrode size.
• Contact area.
• Surface condition.
• Exposure time and current magnitude.
• The size of the surface with which the electrode was in contact.

Precision welding has its niche for application - connecting parts to each other from 0.002 microns to 20 mm. During the process, the current value is measured in hundreds of amperes, and the resistance of the surface and electrodes is minimal.

Advantages of spot welding:

Process used both at home and in industry. It is used to weld the following materials:

• Sheet metal.
• Products made of non-ferrous alloys and steel.
• Bent and sectional profiles.

In everyday life, tools, household utensils, and kitchen equipment are repaired using spot welding. The process consists of combining parts in a certain position. They are fixed between themselves and the electrodes surfaces are heated using electric current before welding. The main thing is to accurately fix the part in the desired position and hold it during the welding process. The thermal impulse melts the metal in the contact zone, connecting the two surfaces into one.

Types of spot welding machines

The simplest spot welding machine is controlled manually; the welding current and operating time are set each time. Requires experience with a specific device. Enough simple design, easy to make with your own hands.

The devices come in three varieties:

Portable devices are not inferior in their characteristics to stationary ones. The welding machine, made in the form of hand pliers, is capable of joining metal 5 mm thick. And with the help of a manual locking drive, a force of 150 kg is achieved. Ease of use, high quality weld, low price, distinguishes this type of device from its competitors.

Inventory devices have small sizes, multifunctionality, easy to connect to a household network. And even high price does not reduce their popularity.

DIY spot welding machine

The simplest one to make at home is a spot welding machine, in which the current strength is not adjustable. And the process is controlled by changing the duration of the electrical pulse; for this, a switch or time relay is used.

The welding machine works on the principles of the Lenz-Juol law: electric current passing through a conductor releases heat, which is directly equal to the square of the current, time and resistance of the conductor. This means that at a current of 1000 A, on thin wires and poorly made connections, the losses will be 10,000 times greater than at 10 A.

Transformer

The main element of any equipment for spot welding is power, with an increased transformation effect (to obtain a normal welding current). It can be take in a powerful microwave (from 1 kW and above), it powers the magnetron. Convenient for its availability and good characteristics. The transformer’s performance is sufficient for spot welding 1 mm steel sheets. To obtain more power, use 2 or more parts.

To operate a magnetron in a microwave oven, you need an increased voltage of 4000 V. Therefore, an increased transformer is used. It has fewer turns on the primary winding than on the secondary, but the thickness of the wire is greater.

The performance of such transformers is up to 2000 V (in a microwave it doubles before being fed to the magnetron), you should not connect them to the network and measure the output characteristics. From this part we need a primary winding (which has a thicker wire and fewer turns) and a magnetic circuit.

The wires are cut with a chisel or a hacksaw (if it is welded and not glued), or they are picked out and drilled out (if the winding is packed very tightly, when knocking it out will destroy everything). When removing the secondary winding wires, try to be careful so that do not damage the primary winding. There are also shunts in the transformer that limit the current; they also need to be cut off.

After carefully removing the necessary elements, the secondary winding of the transformer is updated. To achieve current ratings of 1000 A you need to use a copper cable with a cross-sectional thickness of 100 mm² or more. This can be a bundle or stranded wire. If the external insulation prevents you from obtaining the required number of turns, then it is removed and replaced with fabric insulating tape. The wires should be as short as possible to avoid unnecessary resistance.

No more than 3 turns are made. You will get 2 V, this is enough for home needs. But if you need more current then make more turns, so you will increase the power indicators. Multiple transformers can also be used. This a good option when you have 2 identical ones, but their characteristics individually are not enough to weld metal of the required thickness.

For example, if you have 2 transformers with a power of 0.5 kW, with an input voltage of 220 V, with a rated current of 250 A and an output voltage of 2V. By connecting the terminals of the secondary and primary windings, we get a device in which the rated voltage is 2 V, the output current is 500 A (the welding current will also double).

When creating a device, electrodes must be used in the secondary circuits of the device. That is when using transformers of 0.5 kW, they are tied together with wires with a diameter of 1 cm, and the ends to the electrode. If you make a mistake when connecting the terminals of the secondary and primary windings, this will lead to a short circuit.

When you use two powerful transformers and you need to increase the voltage, but the size of the magnetron window does not allow you to add required amount turns of wire, for this purpose the secondary windings are connected in series. It is necessary to coordinate the direction of the turns, otherwise you can get antiphase, which will lead to an output voltage equal to zero (to correctly understand this point, conduct an experiment with thin leads).

The terminals of the same name are marked on the transformers, but if your device does not have one, you can check it. To the primary windings of transformers voltage is supplied, and a voltmeter is connected to the secondary windings. There can be two results: the device shows voltage or not.

The first case indicates that the circuits of the primary and secondary windings are connected together by opposite terminals (the voltage on the primary winding is equal to half the input, which is converted in the secondary winding, where it is summed up and gives a double value). Null value The voltmeter shows that the voltage values ​​on the secondary windings are opposite, which means that one of the pairs of windings is connected by the same terminal.

To increase the performance of your spot welding machine, you need to connect several transformers, but they should not exceed the network performance, otherwise the total voltage will drop when using it. Limit yourself to 1000–2000 A; for domestic conditions, this current strength is sufficient.

Electrodes

Copper rods are used as electrodes. The greater the thickness, the better, but its diameter should not be less than that of the wire. If you have a low-power device, then soldering iron tips will do.

Electrodes require periodic pumping, as over time they lose their shape and become unusable. The shorter the wire length, going from the electrode to the transformer, the better. The number of connections should be minimal; they also waste power. Ideally, copper tips are attached to the ends, to which the electrodes are connected. Oxidation occurs at the point of contact of copper, to avoid this they are soldered together. This connection is easier to clean.

When using crimping, the fastening area is much smaller, which increases losses.

Control

The device is controlled by a switch or lever. The electrodes must be fastened with such force as to ensure normal welding. The thicker the sheet of metal, the higher the indicator. On industrial devices it reaches 100 kg. Make the control lever long and strong, and the device itself more massive, with the possibility of stationary mounting. Additional force can be added when spot welding using a screw clamp.

The switch is connected to the primary winding circuit, otherwise it will add resistance, and its contacts will melt during operation.

If you use a lever clamp mechanism, then mount the shutdown button on it. It is very convenient to press the lever with one hand and control the work. The second hand controls the welding of parts.

Exploitation

The device must be turned on and off when the electrodes are compressed, otherwise the electrodes will spark and burn. Forced ventilation will greatly facilitate operation, otherwise you will have to monitor the temperature of the transformer, electrodes, conductors and take frequent breaks. In the meantime, you will find by experience temperature conditions elements, something may burn out irrevocably.

To carry out spot welding efficiently, you need experience in bringing together two surfaces of a material, welding with a current pulse, and determining the readiness process by color and appearance.

When carrying out spot welding with your own hands, follow safety precautions; if sparks and molten metal occur, stop work immediately. Operating a faulty device is very dangerous.

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