How to make welding spots - Metals and their processing

Do-it-yourself spot welding - simple detailed instructions for building the machine

In domestic applications, spot welding is used less frequently than arc welding. There are cases when it is difficult to do without it, but if we take into account the price of such devices, the feasibility of purchasing it is called into question. In this case, you can find another way out and look at an example of how to make spot welding with your own hands. For a radio amateur at home, constructing such a device is not difficult. But first you need to understand the features of its work.

How resistance welding works

This is a thermomechanical type of welding. Before starting work, the welded parts are arranged in the desired position. Next, each part of them is fixed between hardware electrodes, under their action the parts are compressed.

The current passing through the electrodes heats the parts, and an alloy is formed at this point. It is the connecting element of two parts. Devices of this type in production have high productivity. They are capable of making 600 weld points in a minute.

But in order for the surfaces to become hot and begin to melt, an electric current of enormous strength is supplied to them. Such an impulse leads to almost instantaneous melting of metals. Its duration depends on the type of metals being fused. Typically the time range is 0.01-0.1 seconds.

In this case, the molten metal surfaces form a welding drop between themselves, which must harden. To do this, the welded parts are kept compressed for some time. The molten drop at this moment forms a kind of crystal lattice.

Pressure plays an important role in this process. It prevents the molten drop from spreading over the area of the parts, thus being held together at one point. The compression force is gradually reduced, then the weld is better set. This work requires clean surfaces of the parts.

Therefore, before work, the intended location of the weld is treated with a special solution. This removes corrosion elements and other oxide films. The result is a high quality seam.

Homemade device designs

Let's look at the structure of a spot welding machine using an example. Let's prepare radioelements and other details:

Electrical converter;
Copper cable with a cross-sectional diameter of at least 10 mm;
Copper type electrodes;
Breaker;
Several tips;
Bolts;
Frame.

Assembling the device

These are the main design details. Now let's look at a diagram for manufacturing a spot welding machine. There are quite a few of them on the Internet. And each has its own set of radio components. But the main similarity of all the schemes is their simplicity and low power.

Therefore, homemade devices are suitable only for small household work. They will be able to weld thin sheets of iron, or wire strands. For the printed circuit board you will need the following elements:

Variable resistor – 100 Ohm;
Capacitor – 1000 mKF, from 25V;
Thyristor;
A pair of diodes - D232A;
Several diodes - D226B;
Fuse – F (fuse type).

The next stage of assembling a do-it-yourself welding machine is to construct the TR1 transformer. It is based on Sh40 iron, the required plate thickness is 70mm. The design has two windings. A PEV2 conductor with a cross-section of 0.8 mm is used for the primary winding. Next, 300 turns are wound.

The secondary winding is made with a multi-core copper cable with a cross-section of 4 mm. The number of turns does not exceed 10.

For the second transformer TR2, no manual work is required. It can be replaced with any weak converter with a power of 5-10V. Its secondary winding should have no more than 5-6V output. The third winding should output up to 15V.

By completing this assembly, you can get a device with a power of up to 500A. The pulse duration will not exceed - 0.1 sec, but only if the values of the resistance and capacitor coincide with those in the diagram. The power of homemade spot welding will allow you to weld metal sheets with a thickness of no more than 0.2 mm, as well as steel wire with a diameter of 0.3 mm.

Types of homemade spot welding machines differ mainly in power. Some models are capable of delivering current up to 2000A, which allows welding steel sheets up to 1.1mm thick and steel wires up to 3mm in diameter.

DIY spot welding photo

Source: https://tytmaster.ru/tochechnaya-svarka-svoimi-rukami/

Description of the process of self-assembly of spot welding

The resistance spot welding machine is very easy to manufacture. It comes in a variety of configurations - from small portable to quite large. Before you begin assembling the structure of a homemade apparatus, remember the Joule-Lenz law, which gives a quantitative assessment of the thermal effect of electric current (Q = I² X R X t).

Given that the amount of heat generated in a conductor is directly proportional to the conductor's resistance, squared current, and time, poorly made connections with thin wires will waste a significant amount of energy. Therefore, special attention should be paid to the quality of the electrical circuit.

In this article we will answer in detail the question: “How to make spot welding at home?”

Due to its simplicity and convenience, spot welding has become widespread

There are three types of resistance welding: spot, seam, butt. A spot welding machine welds parts at one or several points simultaneously. The structure of the welding point depends on the size and shape of the contact surface of the electrode and determines the strength of the connection. A spot welding machine is a type of resistance welding, which is why its technology is based on the thermal effect of electric current.

Brief spot welding technology

Spot welding technology involves several stages. The parts to be joined, aligned in the desired position, must be placed between the electrodes of the welding equipment, pressing them against each other.

The need to press the parts is explained by ensuring the formation of a sealing belt around the molten core. At the moment of the welding pulse, the formed belt prevents the splash of molten metal from the welding zone.

Next, the parts should be heated to a state of thermoplasticity, this is necessary for their deformation. To ensure high-quality precision welding at home, it is necessary to maintain a constant speed of movement of the electrodes, the required pressure value and ensure full contact of the parts being connected.

A spot welding machine heats parts due to a short-term pulse generated as a result of the passage of welding current. This impulse promotes the melting of the metal at the points of contact with the electrode, forming a common liquid core of the parts. The diameter of the formed core reaches 4-12 mm.

Once the current stops, the parts will continue to be held until the molten core cools and crystallizes. Spot welding technology at home is very economical and can provide mechanical strength to the seams. As for the tightness of the seam, this cannot be achieved with such equipment.

Welding processes, the equipment used, as well as safety precautions are strictly regulated by GOSTs. You can check out some of them:

GOST 5264-80 and GOST 11534-75 are designed for manual welding;
GOST 10157-79 and GOST 5583-78 regulate technical conditions;
GOST 15878-79 regulates structural connections of contact welding;
GOST 2601-84 (welding of metals, basic concepts);
GOST 19521-74 - Metal welding and classification.

Homemade spot welding machine design

Such equipment cannot be called powerful. Using it, you can weld a sheet of metal with a thickness of 0.2 mm or steel wire with a diameter of 0.3 mm. Such parameters allow welding thermocouples, as well as welding thin parts made of foil. The welding electrode is made of a gun, since the clamping force of the small-sized parts being welded is small.

Making welding equipment according to this scheme is quite simple. The main equipment unit is the T2 welding transformer. The welding electrode is connected to the secondary winding of the transformer using a flexible cable. As for the larger piece being welded, it is connected to the lower end.

The welding machine is connected to the network using a V5V8 rectifier bridge. The second diagonal of this bridge is designed to turn on thyristor V9; when it opens, voltage is applied to the primary winding T2. In this case, resistance welding pliers act as a gun.

Their technological feature lies in the attachment of a gun to one end of the secondary winding of the transformer, as for the second end, it is attached to the resistance spot welding product itself. Thus, the pliers can perform welding work anywhere on the product using a single electrode. Resistance welding pliers can operate on single-phase or three-phase current.

The transformer from which the resistance welding pliers receive power produces a current of several kiloamperes.

In the handle of the welding gun there is a button S3, when pressed, the thyristor is controlled. When the auxiliary source is connected to the network, capacitor C1 begins charging immediately. Transformer T1 and rectifier bridge V1V4 are an auxiliary source.

Detailed diagram of the point apparatus

The T1 welding machine is turned on by closing the diagonal of the V5V9 bridge with an open thyristor. The thyristor will remain open until capacitor C1 is completely discharged. Variable resistor R1 is provided to adjust the discharge time of the capacitor. To prepare the next welding pulse, button S3 must be released, at which time capacitor C1 will be charged. The next pulse is generated when pressed again.

Transformer T1 can be any low-power one (510 W). The maximum welding duration, with the specified ratings C1 and R1, will be 0.1 seconds.

This provides a welding current of 300500 A, which is quite sufficient when welding small-sized parts.
In this example, the transformer is made of iron.

The thickness of the set is 70 mm; PEV-2 0.8 wire containing 300 turns was used as the primary winding. The diameter of the stranded wire of the secondary winding is 4 mm.

DIY welding machine

The basis of the welding machine is a three-phase step-down transformer. Without disassembling the core, you need to cut through the copper busbar and remove the secondary windings from all coils. The primary wires remain intact, but the middle wire must be rewound with the same wire, forming taps every 30 turns. There should be 8–10 of them in total.

Using a three-phase multi-core power cable, wind the secondary winding around the two outer coils until they are completely filled. The cable should consist of wires D – 6-8 mm, and one of them should be thinner. It is reliably insulated and can withstand high current.

Due to the flexibility of the wire, winding can be carried out without first disassembling the equipment. You will need approximately 25 meters of cable. If necessary, it can be replaced with a wire of a smaller cross-section; in this case, when winding, the cores must be folded in half.

It will be difficult to cope with such a task alone. It is recommended that two people do the work: one pulls the wire, the other lays the turns. To make terminals, you will need a copper tube D - 10 - 12 mm and 30 - 40 mm long.

One side of the tube needs to be riveted, and a hole D – 10 mm must be drilled in the resulting plate. Wires are inserted into the other side and should be thoroughly cleaned. Using a hammer, you need to crimp the stripped wires.

To improve contact, notches need to be made on the surface of the tube.

The standard screws with nuts located on the top of the transformer must be removed and replaced with two new ones with M10 threads, attach the secondary winding terminals to them. A separate textolite board must be attached to the transformer. This is necessary for the primary winding terminals. Before attaching the board, you need to drill 11 holes D - 6 mm in it. and insert screws with two washers and nuts into them.

This is the aesthetic appearance a do-it-yourself spot welding can have

The electrical holder is a 3/4 pipe 250 mm long, with notches cut out on both sides. To ensure free pressing of the electrode, a piece of steel wire is welded to the holder. A hole is drilled on the opposite side and a piece of the same cable that was used for the secondary winding is connected. The pipe must be hidden with a rubber hose of suitable diameter.

Please note: the welding machine is used for a small amount of welding work, so after working with 10-14 electrodes, it needs to be allowed to cool.

A multi-spot welding machine, unlike a spot welding machine, works with workpieces of certain sizes and shapes. A universal multi-spot resistance welding machine is quite rare. Re-adjusting this device is a rather complex and lengthy process.

Electrodes for spot welding

No resistance welding can be carried out without a specific welding attribute called electrodes for resistance welding. For resistance spot welding, special electrodes are used, which are made from alloys with high thermal conductivity.

The electrodes perform the function of compressing the metal and supplying current to the product. The heat concentration during spot welding depends on the tip, so a very thin tip is subject to rapid wear and requires constant sharpening. The most common tip shape is a cone.

In order for the electrodes to serve for a long time, the following conditions must be observed:

Do not use fine tips for heavy welding;
Use specially designed electrodes for a certain material;
Use a water jacket;
Store electrodes in places where they will not be damaged;

It is not recommended to file electrodes for spot welding, as this will cause unevenness and lead to poor-quality welding.

Source: http://zavarimne.ru/oborudovanie/opisanie-processa-samostoyatelnoj-sborki-tochechnoj-svarki/

Do-it-yourself spot welding: diagrams, principle

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.

Household spot welding machine CBA-1.5AK

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.

Equipment for machine spot welding

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.

Spot welding process illustration

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 for crystallization of 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.

An example of a device circuit diagram

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 mm2. The number of turns of the secondary winding is 10.

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 wire Ø0.3 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.

Circuit diagram of a device with a pulse strength of up 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.

Autotransformer 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 mm2. 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.

Source: https://www.asutpp.ru/tochechnaya-svarka-svoimi-rukami.html

How to make spot welding from a microwave or battery with your own hands

Arc welding machines are used in everyday life. Such devices are easy to find on the open market, and they have a relatively low cost. However, situations arise when resistance welding may be necessary. This device has a fairly high cost, and its purchase may not be profitable. To save money, spot welding is done by hand.

Features and principle of operation

Spot welding works using a powerful short-term electrical pulse supplied to the electrodes from an inverter. The parts are heated to their melting temperature, then they are connected to each other. At the junction site, a strong weld remains between the two electrodes. The peculiarity of the work is that the place of spot welding is limited by the diameter of the electrode used.

Before combining the two metal parts, they are pressed tightly against each other. After resistance welding, they need to be kept under pressure.

Spot welding allows you to weld metal in small areas of a car body during body work, solder wires and small parts together, and repair electronics.

How to make spot welding with your own hands from a microwave

A mini resistance welding machine is made with your own hands from some microwave spare parts. For a homemade unit you will need to remove the following components:

Transformer.
Switch.
Power cord.

Removing the transformer

The separation of the transformer from the microwave is carried out according to the following algorithm:

The microwave oven is disassembled.
All fastenings are removed.
The transformer is removed from its seat.
The microwave parts necessary to create a device for spot welding are dismantled.

The extracted transformer has a power of 700-800 watts. This is enough to ensure the connection of metal sheets up to 1 millimeter thick. To manufacture a more powerful spot welding machine, this part is being modernized.

On a transformer, the primary and secondary windings differ in thickness and number of turns. The secondary winding is removed from the part using a chisel and hammer. In this case, all operations are carried out carefully, otherwise the magnetic circuit may be damaged. In this case, the transformer will be damaged.

Instead of the dismantled winding, use a wire whose thickness is at least 1 cm. 2-3 turns need to be wound around the core. This simple upgrade allows you to increase the output voltage to 1000 A.

For a spot welder with increased power, two connected modernized transformers are used.

Transformer Upgrades

When creating spot welding from a microwave, it is necessary to upgrade the welding transformer:

When dismantling the secondary winding, limiting shunts can be found. They are also removed.
The fewer turns of the new secondary winding are created, the lower the resistance of the wire will be, and the greater the current. The cable should not be excessively long.
When winding a new secondary winding wire, difficulties may arise due to the thick insulation. Care should be taken to replace the standard rubberized insulating layer with electrical tape that has a fabric backing. Such a wire should provide an output voltage of 2V and a short-term current of 800A.
The performance of the point device depends on the correct connection of the two transformers. The elements are connected in a circuit. It is necessary to correctly connect the primary and secondary windings of the transformers. This can be done using special markings. If they are missing, then measurements must be taken using a voltmeter.
The design of a spot welding machine used in home workshops involves the creation of a device with a power of no more than 2000A. Otherwise, there will be a load on the home network, which will lead to power outages. This circuit also involves checking the current strength and the presence of short circuits using an ammeter.

After creating the electrical part, install the grounding and switch of the spot welding machine. The part is taken from the microwave. Next, the body, levers, holders and electrodes are made.

Creation of electrodes

Electrodes for spot welding are involved in the supply of current, perform a pressing function and remove excess heat. To create these components, copper is used; this material is resistant to mechanical and chemical influences (the base metal contains impurities in the form of 0.7% chromium and 0.4% zinc). From various videos on the Internet, you can get detailed information about metals suitable for creating electrodes.

Source: https://InfoKuzov.ru/material-instrument/kak-sdelat-kontaktnuyu-svarku

How to make a spot welding machine with your own hands at home: features of the device

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, the upcoming event can become very simple and understandable .

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 parts.

https://www.youtube.com/watch?v=YK3H2eAddTg

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 is formed - a 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, you should pay attention to the following features:

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

The final result of welding activities depends on the correct observance of such rules . 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 build a 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

The key component of a spot welder is the welding transformer, which 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 choose the appropriate device control option, you need to correctly assemble the basic mechanisms . It is no secret that structural parts are selected taking into account the power and parameters of the transformer.

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

When performing any assembly work, be extremely careful and thorough. The 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.

To make resistance spot welding yourself, carefully study the corresponding diagrams. The most popular of them is effective in situations where it is necessary to process metal sheets with a thickness of one millimeter or wiring and rods with a diameter of up to 4 millimeters.

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

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

The entire design is characterized by a 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. The first node is equipped with a transformer for welding T2 and a non-contact thyristor switch of a single-phase type, which connects the primary winding to an 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.

An important part of the system marked M TT4 K is distinguished by mass 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:

power unit.
chain for setting the mechanism.
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 it is necessary to turn on k1 for a given period of time, you need to set this period correctly, determining the specific time for applying 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, it is necessary 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 rings made of electrical cardboard 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:

primary winding with a diameter of 1.5 millimeters, which is impregnated with a varnish composition.
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 a cotton tape , which is also impregnated with a varnish composition. Then the process of secondary winding begins, as well as further impregnation with varnish.

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:

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 power ratings. As for the diameter of the electrode, it must match the diameter of the wire to which it is connected.

In order for the welding cores to 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 a direct connection to the electrical network, individual components of the equipment may be electrocuted.

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. 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.

Source: https://tokar.guru/svarka/izgotovlenie-tochechnoy-svarki-svoimi-rukami.html

How to make a spot welding machine: resistance welding technology and assembly diagrams

Spot welding is a subtype of resistance welding. In this type of welding, metal elements are fastened in one or more places.

This surface welding method has high production technology and a variety of applications in various industrial fields, and can be used in the production of electronic devices, automobiles, ships, aircraft and other industrial production fields.

When using this type of welding, a very high strength of connection between structural parts is achieved. The degree of strength at the junction is determined by the efforts to squeeze the surfaces of the fastened elements and the physical force of the device's electric current.

In modern production, different versions of these devices are used, from stationary machines to easily transportable devices. As an example, the picture shows a photo of a manual spot welding machine.

Hardware Features

This type of welding is based on the method of heating a metal part (plate) with an electric current pulse. To ensure the welding effect, the parts (elements) are strongly pressed together.

At the point of greatest compression, parts are spot welded by passing an electric charge between the electrodes of the device. At the point of contact, a molten point of metal no larger than twelve mm in size is formed.

Spot welding methods

This type of welding is conventionally divided into two methods: soft and hard.

Soft mode. In this mode, when welding, the parts are gradually heated using a low current. It takes about three seconds to weld metal surfaces in this mode.

In this mode, the power consumption of the machine (device) is reduced. The mode is usually used when welding metals with hardening properties.

Hard mode. It is determined by a short duration of high electric current and powerful squeezing of the welded elements at the welding point. The density of consumed electric current in this mode reaches 300A per 1mm2. The welding process takes up to one and a half seconds.

The main disadvantage of this method is the large demand for electricity (machines) and large overloads of the industrial network. The advantage is minimal time for welding surfaces.

This mode is usually used when welding surfaces with good thermal conductivity, high-alloy steel or bonding surfaces of different thicknesses.

Welding options

Types of spot welding are determined by the number of joint pixels formed at a time. The following types are used in production: single-point, two-point and multi-point types.

The single-point type is used when joining several sheets, while the quality of welding decreases with each layer of sheets (parts). The two-point type of welding is used when connecting parts with wide surfaces.

The multi-point type is used to fasten various stamped structures. It can be bilateral or unilateral, it all depends on the placement of the electrodes in relation to the nodes being fastened.

This type of welding can also differ in the cycles of electrical pulses. The cyclicity depends on the thickness of the parts being welded.

For a metal surface up to five millimeters thick, one pulse of electric current is sufficient, but for large thicknesses, several short-term electrical pulses are necessary. When welding metal elements of great thickness and hardness, cycles with increased compression are used.

Welding methods

There are several methods for spot welding:

Spot - welding of elements occurs in one or many places. It is used in instrument making, the automotive industry, and the construction of sea, river and aircraft vessels.

Provides welding of steel sheets up to twenty millimeters thick.

Relief method - structural elements are welded in one or several prepared places. The difference between this method and the previous one is due to the shape of the fastened elements at the welding site.

Seam method - the welded elements are fastened with a series of welding seams. A seam can consist of individual weld pixels or overlapping ones. Used for the manufacture of various tanks requiring a high degree of tightness.

Docking - elements are welded along the adjacent contact area under high temperature. They are used in laying pipelines and making anchor chains for ships.

Design Features

Greater spot welding capabilities are in demand in industrial production. For their implementation, production machines and hand-held portable units have been created.

When solving problems of welding metal elements, you need to remember that this process depends on the metal from which the product is made and its density.

Requirements for technology for performing this type of work:

ensuring low voltage, no more than 10W;
ensuring a short transit time of the electrical pulse at the welding point;
providing high electric current at the welding site;
ensuring a minimum melt area in places where the structure is fastened;
ensuring high quality weld strength.

A modern spot welding machine can have different designs. In modern production, transformer or capacitor spot welding machines are used.

Transformer machines must carry out high-temperature heating of the surfaces being welded. The performance of welding equipment in everyday life can be ensured by an electric current of up to 5 kiloamperes, and in industrial equipment from three hundred to five hundred kiloamperes.

Industrial machines use powerful transformers. The main disadvantage of such devices is the lack of a uniform load, which leads to large overloads of the industrial network and frequent breakdowns.

Capacitor machines load electrical networks measuredly. The use of capacitors in machine tools allows you to avoid sudden overloads of the industrial electrical network.

Manual capacitor welding machines have minimal dimensions and are widely used to solve everyday problems. Their advantages are small dimensions and operability when connected to a household power supply.

Advantages:

there is no need to purchase welding materials;
ease of manufacture;
ease of operation;
cleanliness and neatness of seams or weld points;
compliance with environmental requirements;
min power consumption;
high performance.

We make the welding ourselves

This type of welding tool is not a cheap tool. It is more practical to make a spot welding machine with your own hands.

The main element of such a device is a transformer (used in various household appliances). To provide the necessary electric current for this type of work, it is necessary to rewind its windings. During the creation of the 1st winding, intermediate terminals are also prepared. The wire on the windings must be impregnated with varnish and wrapped with special paper.

The components of the device are selected according to the parameters of the transformer. Its design depends on the parts (surfaces) to be worked on. Electrical elements must be designed with a high degree of reliability.

Pincers can be of two types: stationary and remote. Stationary ones are simpler to manufacture; they are firmly fastened together and reliably insulated. Remote ones are more suitable for use when performing various types of work. They can be easily installed and removed. It is convenient to bring them to the place of direct welding.

When using external pliers, it is necessary to ensure their reliable connection to the device itself and their waterproofing. To make electrodes, you can use copper rods, bronze or an old soldering iron tip.

The electrical diagram for connecting such a device can be easily found on the Internet.

Safety precautions

To ensure their own safety, the worker must know and comply with the safety instructions for spot welding:

To prevent electric shock, ground the unit;
Before starting work, be sure to check its serviceability;
use personal protective equipment for hands, eyes and body;
exclude high voltage supply to the device controls
use only wires of the specified cross-section in the device;
carry out work in a room with well-equipped ventilation or use special masks to protect the respiratory system.
locks and toggle switches (buttons) for turning on or off must be in working order, clearly visible and easily accessible;
During work, the area of the clamping mechanisms must be covered with a shield.

Compliance with these safety measures will ensure the health of the employee and others and will allow the required amount of work to be completed accurately and on time.

Photo instructions on how to make a spot welding machine

We also recommend viewing:

Help the site, share on social networks

Source: https://instrumentgid.ru/instrukciya-kak-sdelat-apparat-tochechnoj-svarki/

How to make a spot welding machine with your own hands

Home plumbing work is part of the life of a business person. One of the most popular home devices is spot welding. It assumes the presence of a factory or homemade welding device. It is not difficult to create a similar device that will be used for spot welding with your own hands; you only need desire and some available tools.

Features and principle of spot welding

Let's start studying the question of how to make spot welding with our own hands with the principle of operation.

Today, spot welding is in demand not only in everyday life, but also in production, as it can solve even the most difficult tasks. In industry, as a rule, devices operating in automatic mode are used; in domestic conditions, a semi-automatic welding machine is used for spot welding.

Spot resistance welding in production is necessary to weld sheet blanks from ferrous and non-ferrous metals. It is used to weld products from profiles of different thicknesses and configurations, as well as intersecting metal workpieces. Under some conditions, it is possible to achieve a high-speed operating mode of up to 600 points per minute.

Many people are interested in the question of how to make spot welding at home? In the home environment, spot welding is used to repair household utensils and, if necessary, to weld electrical wires.

The spot welding procedure includes several stages:

the workpieces are combined in the required position;
fasten the parts directly between the clamping electrodes of the installation;
the surfaces are heated, during which the parts are deformed and they bond with each other.

There is another point connection technology - laser welding. It is capable of performing tasks involving high precision work and extreme soldering strength.

It turns out that the principle of spot welding is the excessive heating of working metal surfaces, which results in their fusion and a single structural new formation.

The main role in the welding process is played by the impulse response of the current, which creates the necessary heating of the metal area. An equally important characteristic is the exposure time and the holding force of the parts. Thanks to these parameters, the metal structure crystallizes.

The main advantages of electric contact welding from a welding machine are:

profitability of use;
strong seam;
simplicity of equipment;
homemade spot welding can be created at home;
possibility of automation in an enterprise environment.

The only flaw in the point connection of parts is considered to be a leaky connection.

The main requirements for welding equipment are:

the ability to change the process time;
creating pressure in the working area, reaching the limit at the end of the heating process;
the presence of electrodes with high energy and heat conductivity.

For household use, electrolytic copper and its mixture of EV grade are suitable. It is worth noting that the area of the contacted area of the electrode must exceed the joint (seam) to be welded by 2.5 times.

Assembling a welding machine yourself

To spot weld parts, it is necessary to create appropriate equipment. A homemade do-it-yourself spot welding installation can have any shape - from portable varieties to large-sized models. In practice, desktop versions are usually used, used for joining various metals. Before you create spot welding from an inverter, you should familiarize yourself with the materials that will be needed during manufacture.

energy converter, that is, a transformer;
electrical cable with insulation with a cross-section of 10 mm;
copper electrodes;
breaker;
tips;
bolts;
available tools and materials for creating a frame base or welding pliers (blocks of wood, recycled materials, plywood).

1 — modified OSM-1.0 transformer; 2 — conductor (duralumin rod with a diameter of 30, L300, 2 pcs.); 3 — liner (steel rod with a diameter of 10, L30, 2 pcs.); 4 — electrode (copper rod with a diameter of 12, L50, 2 pcs.); 5 — brass washer (2 pcs.); 6.12 — M6 screws; 7 handle; 8 - eccentric; 9 — cheek (2 pcs.); 10 - spring; 11 — output of half of the secondary winding (4 pcs.); 13 — textolite bushing (with a groove for the end loop of the spring); 14 — M8 bolt (6 pcs.); 15 — textolite washer (4 pcs.); 16 — insulating coating (varnished fabric or protective adhesive tape on a fabric basis, 2 pcs.); 17 — transformer casing.

Installation diagrams

The main types of welding device assembly schemes are simple projects with a minimum amount of required materials. It is worth noting that the manufactured equipment will not be powerful, that is, this spot welding scheme is intended only for domestic use. Its purpose is to weld small sheets of iron and electrical wires.

To understand how to do resistance welding, remember the school curriculum, namely the physical rule “Joule-Lenz Law”: when electricity passes through a conductor, the amount of thermal energy created in it is directly proportional to the resistance of the conductor, the time of exposure and the square of the electric current. Conclusion, if the current was initially large (for example, 1000 A), then with a weak connection and small wires more energy will be consumed (several thousand times) than with a lower electric current (10 A). That is, the quality of the assembled electrical circuit plays an important role.

The formation of an electrical pulse between two sections of metal products is considered a basic part of the operation of a welding installation. This will require a small energy converter. The product to be welded must be connected to the lower winding of the device, and the metal electrode to the secondary.

It is worth noting that it is unacceptable to directly combine the converter with the power source. For this purpose, a bridge with an electronic switch (thyristor) is provided in the electrical circuit. To create the required pulse, the device must be supplied with auxiliary power, which includes an energy rectification bridge and a transformer. The electric current will be concentrated in a capacitor, whose role is to generate a pulse.

In order for a home-made resistance welding machine to work, you need to press the “pulse button” on the handle of the gun to open the capacitor-resistor circuit diagram. As a result of these manipulations, a discharge will occur through the metal rod. To reinforce the theoretical material, it is recommended to watch the training video, which explains in detail about spot welding. This allows you to visually understand how this is all done correctly.

Homemade device from a microwave oven

Since it is not always possible to allocate an extra amount of money for spot welding machines, you can make it yourself. This will require a fairly powerful microwave oven.

Transformer assembly

You only need one part from the microwave - a high-voltage transformer for spot welding. This part requires only a core (magnetistor) and a primary (lower) winding. To remove unnecessary areas, you can use a hammer, grinder or hacksaw.

After removing the transformer secondary winding, it is necessary to create a homemade transformer for resistance welding. To do this, you should use a copper cable with a diameter equal to the opening of the transformer. It is necessary to make two turns.

In order to connect the two parts of the core you will need epoxy resin.

Next, you should test the output voltage from the device. The optimal value is considered to be 2 volts, and the current strength is about 850 amperes.

The base is done, now we need to work on the body of the homemade installation. For this purpose, various polymers are used, for example, plastic or wood. The back area of the point installation housing should contain several openings. One opening will serve as the key for the device, and the other will supply electricity.

If wood is used instead of plastic, then first you should perform several preparatory operations, namely sanding, impregnation and varnishing. To create a homemade working machine for spot welding with your own hands, you will need:

welding installation power cable;
Door knob;
switch;
copper holders;
large diameter electrical wire;
consumables (screws, nails).

After the body section has dried, it is necessary to assemble the installation and combine all the associated parts. After this, the copper wire is cut into 2 parts, each of which is approximately 25 mm. These elements will perform the function of electrodes.

To fix them, just use a standard screwdriver. Then you need to install the system key; a thick electrical cable will prevent it from slipping out.

To fix the transformer to the structure body, you can use self-tapping screws, but do not forget about grounding one of the terminals.

To increase the safety of using the welding device, it is recommended to install an auxiliary switch. Small nails and other fasteners are also used to secure the working arms. Contact metal rods are attached to the end parts of the handles. To raise the upper handle, a standard polymer is used - rubber.

Controls

The do-it-yourself resistance welding has a simple device. There are only two control systems - a switch and a handle. The spot welding switch is fixed in the primary winding circuit.

This is necessary because there is more current in the secondary winding, and the switching system will create additional resistance. The switch is installed on the lever, so it will be more convenient to work.

That is, you can turn on the electricity with one hand, and hold the materials being welded with the other.

It is worth noting that turning the welding current on and off must be done only with the electrodes compressed, because otherwise a spark will appear, leading to their burning. It is also recommended to use a fan to cool the device.

If such a cooling system is not available, then the temperature of the energy converter, metal electrodes, electrical wires should be constantly monitored and additional breaks should be created to prevent overheating.

Today, purchasing a welding machine for spot welding is not a problem if you have the money. Any specialized store will offer a range of installations for point joining of parts, with different capacities and manufacturers.

But for home craftsmen it is not always possible to select the required parameters, so making a spot welding machine with your own hands will be the optimal solution. All necessary supplies can be borrowed and found at home.

A do-it-yourself spot welding installation does not fail and works perfectly, thereby providing the required minor repairs to metal products.

Source: https://oxmetall.ru/svarka/kak-sdelat-apparat-dlya-tochechnoj-svarki-svoimi-rukami

Do-it-yourself spot welding/spotter from the microwave

Spot welding is quite in demand in industry. It allows you to quickly and strongly heat a local area of metal. With its help, you can weld individual metal rods in a mesh or two sheets of metal. It will also be useful for unscrewing rusted nuts and bolts; you just need to heat them with this device.

Body repair using spot welding.

Spot welding of two metal plates.

Heating a rusted nut by spot welding.

The operating principle of spot welding is quite simple. The parts to be welded are placed between two electrodes, which exert a compressive force and a high current flows through them, from 500A and above. As a result, the metal is heated to a temperature where it becomes plastic and thus a permanent connection is formed after the workpieces being welded have cooled.

Schematic illustration of the operating principle of spot welding.

The industry uses quite serious spot welding machines that have water-cooled working electrodes and pneumatic clamps. Such devices allow you to weld a large number of points in a fairly short time. But for home use, a simpler device is sufficient.

Spot welding and safety.

This type of welding is quite safe despite the fact that high currents are used to heat the metal. But in addition to the high current strength, a voltage of only 1-3 volts is created on the electrodes. Let us recall Ohm's law for a section of a circuit.

Ohm's law for a section of a circuit.

Substituting a voltage of 2 V and a resistance of 1000 ohms (human resistance) into the formula, we obtain the current strength that will pass through a person - 0.002A. A current of up to 0.1A and a voltage of up to 42V are considered safe.

DIY spot welding assembly from a microwave oven.

In order to make a spot welding machine, we need a transformer. Let's take it from an old, non-working microwave oven. The main thing is that it has a working transformer. Not even necessarily the entire transformer, but only half of it. We only need its working primary winding. The secondary winding is not needed and will have to be removed from the transformer.

Important! Do not under any circumstances connect the transformer to the network in this form! This transformer is a step-up transformer and creates a very high voltage on the secondary winding, about 2000 volts.

Transformer from a microwave oven.

It is very easy to distinguish the secondary winding of a transformer from the primary. The primary winding is wound from wire of a larger cross-section than the secondary and there are fewer turns of wire on the primary winding.

We remove the secondary winding of the transformer. This can be done in different ways. It can be cut with a grinder or a hacksaw. Since copper wire is quite soft, it can be cut with a chisel or chisel. When removing the secondary winding, it is very important not to snag the primary winding. If you damage it, the transformer will have to be thrown away or scrapped.

Removing the secondary winding of a transformer using a grinder.

Removing the secondary winding of a transformer using a hacksaw.

Removing the secondary winding of the transformer using a chisel.

After the protruding parts of the secondary winding have been removed, it is necessary to knock out the remaining windings from the middle of the transformer.

Knocking out the secondary winding from the transformer.

If the winding does not come out, then drill it out using an electric drill, and then remove the remains.

After removing the windings, you need to remove the shunts. They are a set of metal plates wrapped in paper. In the photo below they are circled in red.

Shunts in a transformer.

The purpose of the shunts is to short-circuit the primary winding along the magnetic flux and reduce the flux through the secondary winding. In simple terms, shunts reduce the current on the secondary winding, and therefore reduce the power of our welding machine. Therefore, they must be removed.

Now is the time to tackle the cable. The wire must have copper cores. The wire length is approximately 1.5m. For a welding machine, a wire with a cross section of 50mm2 is best suited, which is approximately 8mm in diameter without insulation. During operation of the welding machine, this wire will heat up from the current passing through it. And the smaller the cross-section of the wire, the faster it will heat up. Therefore, it is advisable to use a wire with as large a cross-section as possible.

If the wire is difficult to screw onto the transformer, then you can remove the insulation from it, wrap it with cotton tape and put a heat-shrinkable tube on top. Thus, the cable with new insulation will become slightly smaller in diameter. The electrical tape must be cotton. It does not melt when heated, unlike regular electrical tape.

In the same way, you can make a wire of the required diameter from several wires of a smaller cross-section, after first removing the insulation from them and twisting them into one core.

All that remains is to put special crimp terminals on the wire. You can simply compress them by flattening them with a hammer or in a vice.

Wire wrapped with electrical tape.

Wire in heat shrink tube.

Crimp terminal.

Wire for the secondary winding of the welding machine.

Now we wind the wire around the transformer. It is necessary to make two full turns as shown in the photo below.

Transformer with new secondary winding.

You can start testing the transformer.

Heating a bolt with a diameter of 5mm using a welding machine.

The bolt is destroyed by heat in just 4 seconds.

The power part of the spot welding machine is ready. All that remains is to make contact pliers with copper electrodes. They can be of very different designs. You can make them at your discretion from various materials. Below, see options for manufacturing contact pliers for a spot welding machine.

An example of homemade contact pliers of a spot welding machine.

Source: https://delairukami.ru/avto/tochechnaja_svarka/

How to make spot welding with your own hands?

How [do-it-yourself spot welding] is carried out, what kind of apparatus is used, is it possible to do it yourself - below we will try to answer all these questions.

Technological process

Spot welding is used not only in production, but also at home.

On an industrial scale, the choice falls on this type of welding when it is necessary to join alloys of non-ferrous metals, steel of various grades, when sheets have different thicknesses, when creating profile workpieces, for example, angles, etc.

At home, spot welding has found its application in the repair of household appliances, batteries, and cables.

To reduce the cost of replacing system batteries, this machine can be used to weld batteries for laptops, screwdrivers and other mobile devices.

Welding of batteries occurs using conventional technology.

The welding process itself consists of heating a metal object to a state of plasticity, after which it is deformed, that is, connected.

To create a better quality seam, it is necessary to ensure consistency of the process, that is, constantly maintain the same speed of processing the object, and monitor the pressure.

These requirements apply more to manual welding, since in enterprises this process is performed automatically.

Heating of metal objects occurs by passing an electric current, which generates heat on the surface.

In the place where the electrode came into contact with the surface, a liquid core begins to appear, formed from the melting of two parts.

When the current stops flowing (0.01-0.1 sec), then the core begins to solidify, thereby allowing both parts of the parts to be held.

To compress a metal sheet, pliers are used, which are divided into manual and suspended.

Hand pliers help generate current, which is subsequently supplied to the electrodes that clamp the workpiece. Hanging pliers are used in industry and are characterized by high productivity.

Resistance spot welding has a number of advantages:

Speed of work;
Safety of work is achieved due to low voltage;
The strength of the connection is ensured, but, unfortunately, not tightness;
You can make a welding machine yourself at home.

Process Features

Resistance spot welding is a simple process: current passes through the spot connection, generating heat.

At the same time, the condition of the contacts affects the quality of welding; any roughness or oxide can have an adverse effect.

IMPORTANT TO KNOW: Selecting and designing a hair dryer for soldering microcircuits

See the video for the spot welding process.

When welding, it is necessary to take into account such properties of metals as thermal conductivity, resistance and melting point, since they are different, for example, iron will melt at a temperature of 1300 degrees Celsius, copper - 680, aluminum - 435, zinc - 1115, etc.

Electrodes also have certain requirements:

High rates of heat and electrical conductivity;
Strength;
Mechanical processing should be easy.

To extend the life of the electrodes, it is recommended to cool them with water during operation.

The quality of the weld seam also depends on the diameter of the electrodes; it determines the current density.

In order to visually correctly select the diameter of the electrode for the sheet being processed, it is necessary to multiply its thickness by two.

Resistance spot welding can be carried out not only on an industrial scale, but also at home.

To avoid having to use bulky equipment at home, manufacturers have released a compact device suitable for minor repairs, for example, household appliances, batteries or a car.

The device is called a spotter. It has two terminals, one of which is attached directly to the object, and the second to the electrode.

In this case, pliers are not needed. To ensure a better working process, it is advisable to select the power source so that it is located as close as possible to the welding site.

Despite the fact that the spotter is more of a hand-held device, it is quite functional.

The simplest devices using single-phase current are reliable and simple, but metal sheets thicker than 0.8 mm cannot be connected.

More complex and powerful models use a transformer; it should be noted that they are more expensive. But the most expensive spotter is the inverter one.

In everyday life, you can get by with a cheaper device made by yourself.

Spot welding is characterized by the strength of the seam, which sometimes has to be removed by drilling. The drill is usually used when repairing a car.

It should be noted that there is a special drill for drilling spot welds. It is better to buy a drill rather than use some drill that you think is suitable. The price for such a drill is low. This work must be carried out carefully so that the body can be repaired in the future, rather than ordering a new one.

Diagram of a homemade welding machine

For everyday needs, there is no reason to buy a welding machine, especially since you can make it yourself.

IMPORTANT TO KNOW: Lessons on semi-automatic welding for beginners

The dimensions of such a device will directly depend on the needs. It is more convenient to assemble a medium-sized device. Below is a diagram of a spot welding machine.

); 10 - spring; 11 — output of half of the secondary winding (4 pcs.); 13 — textolite bushing (with a groove for the end loop of the spring); 14 — M8 bolt (6 pcs.); 15 — textolite washer (4 pcs.); 16 — insulating coating (varnished fabric or protective adhesive tape on a fabric basis, 2 pcs.); 17 — transformer casing.

The operation of the welding machine is based on the physical law of Lenz-Joule.

The meaning of the law is that the conductor begins to generate heat by passing electric current through itself, in an amount proportional to the resistance of the conductor material, the square value of the current and the time it takes for the current to “pass.”

Wires are selected taking into account this law.

Since resistance spot welding occurs due to an electric pulse, to create the device you will need a transformer, which is not recommended to be connected directly to the power source.

A rectifier bridge with a thyristor is required for proper connection.

The circuit of a homemade device involves the use of another power supply with a transformer and a rectifier bridge for more power.

The current is collected and the pulse is created using a capacitor.

The bridge of the first transformer is closed by a thyristor, which acts as a cathode.

It will remain open until the capacitor is completely discharged. “Impulse” is the beginning and end of the welding machine.

To create a more powerful device, the circuit changes slightly: it is necessary to add a semiconductor thyristor and a time relay.

Homemade welding machine

The circuit is the basis for creating a welding machine, and its “heart” can be considered a transformer, which will create the necessary voltage.

It’s worth noting right away that this element must be powerful with a minimum value of 700-800 watts.

You can make a homemade welding machine using an inverter, but this requires certain knowledge and skills. Using a transformer rather than an inverter is an easier way to create a homemade machine.

IMPORTANT TO KNOW: Inverter-type semi-automatic welding machine

The transformer can be taken from the microwave. Moreover, an old device is suitable for this, or a microwave oven can be purchased specially second-hand.

The scheme of further actions is as follows:

You need to carefully remove the transformer from the microwave, removing all fasteners and disassembling the base;
The secondary winding from the microwave transformer must be knocked down. You can use any available tool: hammer, chisel, pliers, drill, etc. By the way, a drill should always be at hand when using spot welding. The secondary winding differs from the primary winding by a thicker wire. You also need to act carefully here so as not to damage the wire used for the primary winding;
It is necessary to make two or three turns of a new secondary winding. To obtain a current of 1000A, it is advisable to take a wire whose thickness will be at least 1 cm. Physically, it will not be possible to make more than three turns, so if necessary, add another transformer from the microwave, as mentioned above;
The next step is to check the winding for short circuits. A voltmeter is used for this. If none are found, then work can continue;
Next, the transformer from the microwave is checked with an ammeter. If the current exceeds 2000A, then it is necessary to reduce it in order to avoid future voltage drops.

Copper wire works well for electrodes. The thickness of the wire is selected so that the diameter of the wire does not exceed its diameter.

You can use two soldering irons, or rather their tips, which can be installed as electrodes.

Current losses can be reduced by shortening the length of the wire coming from the electrode.

The wire is connected to the electrode using a copper tip; a hole can be made by drilling, using a drill bit of 8.

If you solder the tip to the wire, you can avoid oxidation, which is inevitable when you turn it on for the first time.

Next, to ensure the safe operation of a homemade welding machine, it is necessary to make a housing. The best material for this is wood.

When creating levers, the following point must be taken into account: it is necessary to create free movement of the upper lever horizontally and vertically; this can be done using special openings in the body.

If desired, you can make the lower arm in the same way.

It is necessary to provide space for the on/off switch on the back cover of the device. After installing the toggle switch, the power cable is inserted.

To eliminate the possibility of the cable falling out, it must be made thicker and thicker.

The microwave transformer is attached to the base using self-tapping screws. A terminal is put on the mount and grounding is done. All connections must be carefully insulated.

To keep the upper arm raised, you can use a regular rubber band placed on two self-tapping screws.

Watch a video about do-it-yourself spot welding in our article.

Source: https://rezhemmetall.ru/tochechnaya-svarka-svoimi-rukami.html

THIS IS INTERESTING: How to sharpen a copper soldering iron tip