Making a spotter with your own hands. Resistance welding Machine for spot welding by hand from an inverter

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 living conditions apply semi-automatic welding machine 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 profile products different thicknesses and configurations, intersecting metal blanks. 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 for repairs. household utensils and, if necessary, 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 to excessively heat the workers metal surfaces, the result of which is their fusion and a single structural new formation.

The main role in the welding process is played by impulse response current, which creates the necessary heating of the metal area. No less 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 welding machine are considered:

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 it is usually used desktop options, 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 tissue based, 2 pcs.); 17 - transformer casing.

Installation diagrams

The main types of welding device assembly schemes are simple projects with a minimum amount of materials required. It is worth noting that the manufactured equipment will not be powerful, that is this scheme spot welding is intended for domestic use only. 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 great importance(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 impulse between two sections of metal products is considered basic part operation of the 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. Electricity will be concentrated in a capacitor, whose role is to form 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 secure theoretical material, it is recommended that you 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 one on our own. 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.

The base is done, now we need to work on the body 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 contacts are attached to the end parts of the handles. metal rods. To raise the upper handle, a standard polymer is used - rubber.

Creation of electrodes

Elements used for do-it-yourself spot welding must meet certain requirements, namely resistance to operating temperatures, good electrical conductivity and ease of machining.

Copper wires with a cross-section of 15 mm or more are perfect for this. The basic principle is that the cross-section of the electrode should not be less than the diameter of the wire. If you don’t mind, you can use the tips of 2 soldering irons, which will definitely last a long time.

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 on and off the welding current must be carried out only with compressed electrodes, 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 optimal solution. All necessary supplies can be borrowed and found at home. Collected with my own hands The spot welding installation does not fail and works perfectly, thereby providing the required minor repairs to metal products.

A spotter is a spot welding machine that is widely used for automotive straightening work. Very often, such work requires maximum geometric accuracy and knowledge of all body panels located on the car. And it’s rare that high-quality straightening can be done without special devices, in particular, a spotter.

Today we will talk about how to assemble a spotter with your own hands and what is the scheme of its operation. So, homemade spotters will save a lot of money if you make them from a welding machine.

Features of using a spotter

A device such as a spotter is used for the following needs:

body welding work;
straightening the body surface without disassembling the trim.

Especially the spotter convenient for straightening body parts, which are difficult to access due to certain design features. When repairing body parts using a spotter from a welding machine, you need to weld a special fastener to the deformed part, which reverse hammer pulls out damaged metal. The spotter is also able to heat it, so the metal quickly returns to its rigidity and shape.

How does the spotter work?

There are several electrical circuits for a spotter that can be assembled not only from an inverter, but also from an old battery or transformer. Homemade spotter acts like a hammer, works in a pointwise manner, but in the opposite direction. It looks like this:

the return hammer of the guide is fixed to the damaged area on the body;
Only a hammer in the form of a washer can move along the guide, which applies force to the point of its fixation.

A regular spotter has two modes of operation;

short-term, when the guide needs to be fixed in the right point special rings;
welding - welding is carried out at minimum power using a carbon electrode.

DIY spotter based on inverters

The welding machine spotter is the most common among homemade devices, despite the fact that there are other schemes for their assembly. So, you can assemble spotters with your own hands without using welding machines, but they will be less powerful.

The spotter is a branch of resistance welding, however, unlike it, the design of the spotter eliminates the presence of ticks, which is why this device can be considered an analogue of an electric arc welding machine, where voltage is passed through a car body. One contact is attached to the body, and the second contact is a rod and a nozzle.

Below we invite you to familiarize yourself with the simplest scheme of a spotter based on a welding machine, which you can modify if you wish.

Inverter spotter circuit

The spotter, assembled with your own hands from a welding machine, includes two key elements:

welding inverter;
thyristor relay.

To assemble this device yourself you will need:

200 volt thyristor;
a 12-volt step-down transformer for push-button control of the relay;
30 amp relay;
diode bridge;
contact group (220 volts);
control button.

Via diode bridge the transformer is connected to the network, and an electronic relay thyristor must be connected to the bridge. The transformer is designed to power the control branch of the thyristor circuit.

The spotter's operation scheme looks like this:

when you press button S3, capacitor C1 is discharged, and resistor R1 and thyristor V9 are turned on for a while;
then alternating voltage is supplied to the primary transformer winding using D232 diodes;
the welding procedure of parts and electrode takes place;
when capacitor C1 discharges, the thyristor closes and the winding power transformer de-energized;
in this state of affairs, the welding process comes to an end, and capacitor C1 continues to be charged from transformer T1 for subsequent work.

Remember that the diode bridge and thyristor can be replaced with triacs. Homemade spotters must be carefully designed from a constructive point of view. It should work correctly regardless of size and investment.

Materials

Iron for a spotter should be allocated in a volume of 35 to 40 square centimeters. Overheating does not occur on the thyristor; it occurs only in areas located after the cable. Also The ferrous metal rod gets very hot 16 mm in diameter. It is desirable that it be made of brass.

As for the cable for the spotter, you need to choose one with a cross-sectional area of about 70 square millimeters, and for the mass and the hammer its length of 1.7 and 2.1 m will be sufficient, respectively. It will also be necessary to provide pulse control on the thyristor ТЧ-40.

First, the secondary winding of the transformer is wound using a 6.5 by 4 copper bar in the third winding. It can also be replaced with aluminum. Then you need to add two more to the secondary winding. The final version of the device consists of an aluminum transformer winding of 250 square millimeters, which is equal to 5 windings of six turns.

Pay close attention to the appearance of the reverse hammer, which acts as an electrode. More often the handle is made on the basis glue gun , and the working cable has a thermal insulation layer and a commutating wire. Also remember that when heated, the thermal insulation layer begins to shrink.

Key functions and technical characteristics of the spotter

A homemade or factory-made spotter with an industrial purpose has a number of important functions:

Basic specifications devices:

220 volts is the required supply voltage for normal operation spotter;
56-60 Hz – required AC mains frequency;
10 kW – maximum permissible power;
1300 A – maximum possible operating current;
about 8-9 V – voltage for the secondary winding of the welding machine;
0-1.2 seconds – time setting limit;
two operating welding modes - a timer for precision welding and a continuous mode for conventional welding and tempering;
15 percent – productivity when spot welding metal parts, taking into account the maximum output power;
75 percent - productivity with coal boiling, taking into account the maximum output power;
from 100 kg and more – traction condition for the needle;
100 kg and above – traction condition for the puck;
380 by 290 by 840 mm – length, width and height of the product;
32 kg – weight of the structure.

There is a recognized technology for working with a spotter, which was determined by body repair specialists. It is relevant when repairing hard-to-reach deformed parts of the car body. Often this scheme of work is applied to deformed car doors, fenders and other parts of the vehicle. It is relevant wherever efforts are directed towards outside working surface and where the deformed section of the structure is located.

Spot welding is performed using an incoming current, and then the local surface is leveled with a stop or an inertia hammer. Thanks to such manipulations, the damaged part of the car will quickly be pulled back to its original position.

Then the deformed and leveled surface is ground. This must be done so that the points are removed from welding and working surface was smooth. Do not forget about the mandatory grounding for the case, the negative terminal must also be disconnected from the battery.

The welding technology using a spotter is as follows:

Carefully clean the deformed area on the automobile part until the metal surface is visible;
attach a grounding contact to the prepared surface;
weld fasteners;
grab these elements with special devices and tools that will be needed for melting metals;
we pull out the deformed section of the surface of the metal structure;
the welded element can be easily removed with your own hands using rotational movements;
Clean the surface of the part that was repaired and prepare this area for putty.

To work with a spotter, regardless of whether it is homemade or factory-made, you need to have the skills welding work. Also You must follow the operating instructions for this device. and follow the rules for welding work. All this will allow you to repair the deformed part of the car quickly and successfully.

The spotter will become indispensable when performing all kinds of repair work on the car body, requiring point concentration. And as you can see, this device can be assembled with your own hands.

Do-it-yourself spot welding from an inverter - is it a myth or reality? It is not at all easy to answer this question clearly. You can find many articles on this topic on the Internet. Their authors, as a rule, deal with the problems of altering electrical and electronic components. The question of how to create the necessary working pressure on the electrodes seems to fade into the background. But it is, in fact, key, since we are talking about an effort of tens and sometimes hundreds of kilograms. Well, okay, let's take it in order.

The advantages of resistance welding are sufficient to make it attractive to those who intend to launch mass production of products or repair equipment at a professional level.

Good quality welded joint. It is ensured by the stability of the parameters of the welding current and pressure exerted on the parts being joined.
High speed of the process. It takes seconds to apply a suture. This is especially important when it comes to performing large volume works
Operational simplicity. A properly manufactured resistance welding machine does not require special skills to use, and even a semi-skilled specialist can master the process.
The use of a spotter is justified when repairing automobile bodies. This device simplifies not only the welding process, but also the straightening of damaged parts.

The main obstacle to widespread adoption of the technology is high price equipment. This gives many people the idea of making a resistance welding machine on their own.

Do you need an inverter?

In fact, using an inverter for these purposes is unjustified. After all, for resistance welding there is no need for DC. If you have a ready-made welding inverter, the task of installing control circuits and manufacturing transformer coils of the required parameters is only slightly simplified. With the same success, you can make equipment, as they say, from scratch.

What you need

It is not worth starting to solve such a problem without the necessary theoretical knowledge and practical skills. In words it all looks relatively simple. But if you know how to solder and know how to rewind the transformer coils correctly, you can try it. For this you will need certain materials and tools.

Copper wire of a certain cross-section. Its cross-section and quantity can only be determined by performing preliminary calculations.
Material for making a tire. At worst, you can get by with the same wire, but it is more advisable to purchase a ready-made product.
Varnish to create an insulating layer on the wires and good insulating tape.
Multimeter for taking the necessary measurements.
Soldering supplies – soldering iron, flux, solder, etc.

Of course, you will have to purchase a ready-made welding inverter.

Transformer manufacturing

Figure No. 1 schematically shows the possible ratio of turns of the primary and secondary windings of the transformer necessary for resistance welding. Big number outputs on the secondary winding are necessary in order to be able to roughly adjust the current parameters. But the presented circuit requires adjustment depending on the required current parameters. You can't do without preliminary calculations.

Theoretical and practical assistance

The number of turns can be calculated using this formula: N = 50/S. Where N is the number of turns, S is the core area in cm2. To simplify the task, it is recommended to use a ready-made calculator program. They can also be found online. For example, the OER program. This will help avoid mistakes and simplify the task. Since we are talking about designing equipment based on a ready-made inverter, you should first measure the parameters of the primary coil, make calculations, and only then begin manufacturing the secondary winding.

Carefully!

Care must be taken to ensure that both windings are grounded. After all, the resulting current power will be very high, and contact with live parts can be fatal.

Carefully insulate and cool well

When winding wire onto a coil, be sure to apply insulating varnish to its surface and lay the turns as tightly as possible. Otherwise, interturn short circuits and wire burnout due to overheating cannot be ruled out. Transformer cooling comes to the fore. For some reason, the authors of many articles are silent about this. It is possible that installation will be required additional system cooling, consisting of radiators and fans blowing them. If this is not taken care of, the equipment will simply fail due to overheating or even become a fire hazard. As an option, it is possible to install ready-made cooling systems used in electrical and electronics.

Control system installation

When installing the control circuit, it is recommended to use ready-made elements. They are already in the factory inverter. This will greatly simplify the assembly process and make the device convenient to use. But the capacity of its standard capacitors may not be enough. In this case, they will have to be replaced with parts that match the parameters. The current parameters in the resistance welding machine are adjusted in stages. Its accuracy will depend on the number of pins of the secondary winding and their pitch. This is necessary if equipment capable of operating in different modes is required.

It is important!

Installation of circuit components should be done using soldering. Detachable connections are not able to provide the required heat transfer mode. Their use makes sense only in cases where frequent replacement of any parts is expected.

Making pliers

Only when the transformer is ready does it make sense to start making contact clamps. Their design primarily depends on the nature of the work for which the equipment will be used. The gripper design will depend on its drive system and the expected size of the parts to be connected. An important part of the pliers are the contact tips. If the thickness of the sheet being welded is small, it is quite acceptable to use copper tips from a soldering iron. It is better if you purchase and install ready-made tips - they are available for sale and are convenient because they have a special shape that is well suited for the job. But if we are talking about steel sheet 0.5 mm or more and it is expected to apply connecting seams of considerable length; it is recommended to equip the tips with rollers.

Providing clamping force

Next you will have to decide in the most practical way difficult task. The fact is that if you intend to create pressure on the welding tongs manually, it is better to refuse making contact welding. The efficiency of such a device will be low. The applied force at the welding site must be uniform and very significant.

In industrial settings, hydraulic or pneumatic systems are used for this. Making such a device yourself is extremely problematic. It makes more sense to purchase a ready-made booster, since they are available for sale. When making resistance welding with your own hands, it is easier to use amplifiers driven by compressed air. In this case, for their operation it will be enough to connect a conventional pneumatic compressor. It is optimal if the maximum force on the contacts reaches 100 kg or more. To change the pressure, you can use a separate regulator, or integrate it into the overall control system of the device.

Gas supply

To optimize welding conditions and improve the quality of the connecting seam, it is worth taking care of the gas supply to the working area. In the case of steel, this should be carbon dioxide. The selection of nozzle and its location depend on the size of the pliers, contacts and working area. The supply hose is secured so as not to interfere with the operation of other components of the device. It must be made of non-flammable, heat-resistant material and equipped with a control valve.

Concern for reliability and safety

For efficient work equipment, and in order to ensure safety standards, all components of the device must be carefully secured and insulated. It is recommended to use dielectric materials with good heat resistance and mechanical strength as a basis. It is also necessary to take care of integrating protective fuses into the electrical circuit. It is important to follow all recommended safety precautions when working on equipment.

It differs from the usual arc in that the metal does not melt at high temperature an electric arc that occurs between the electrode and the metal being welded, but due to the passage of current through the contact of two parts being welded. These details may be thin sheets metal, wire, plates. They are firmly compressed by special mechanical devices and a pulsed current is passed through the junction high strength(1000 or more Amperes) at a voltage of several volts.

Do-it-yourself spot welding assumes that per 1 mm 2 of contact area there is at least 5 kW of power, which corresponds to a current strength of up to 50 A/mm 2. In this case, the mechanical pressure per square millimeter should be at least 3-8 kg. To achieve such parameters, a special design of a working tool in the form of pliers is required.

The working body is two conductive electrodes that compress the parts being connected with the required force when pressing the handles. After compression, a current pulse of 01-1 s duration is applied to the electrodes, which melts the metal to a plastic state. After the current supply is stopped, the mechanical effect remains and the molten metal merges into one whole and thus solidifies, forming a strong connection that is not inferior to electric arc welding.

The welding diagram looks like this:

The main difficulty in making a spot welding machine with your own hands is assembling the power source. It must produce short pulses of low voltage and high current, exceeding 1000A. Pulse duration is adjustable thyristor circuit or manually with a conventional switch on the primary winding. For low-alloy steels, a longer pulse is required; stainless steel is welded with short pulses so that the upper part does not have time to warm up and oxidize, which significantly reduces the anti-corrosion properties.

In the second case, welding with such a machine requires a certain skill - it is very difficult to guess the required pulse duration the first time, especially on different metals. But by trial and error, using scraps of sheet steel or non-ferrous alloys, it is quite possible to achieve welding quality no worse than on industrial machines.

Spot welding, assembled with your own hands from an old welding machine, works quite effectively and is quite capable of solving a number of connection problems sheet metal thickness from a few tenths to 2-3 mm. For thicker sheets, it is difficult to create the required force using homemade pliers or a lever device.

Why is an old transformer chosen? A do-it-yourself spot welding machine involves its complete re-equipment, which, however, only concerns the secondary winding. After the alteration, ordinary MMA welding with such a device becomes impossible, so an old, but still working device is selected; at least the primary winding should be, if not in ideal, then in acceptable condition.

The secondary winding is completely removed and another one is installed in its place, made from an insulated copper strand or busbar. The wire must be insulated very carefully, in several layers of non-flammable insulation. Fabric insulating tape is convenient for these purposes, which alternates with wrapping with ordinary automotive tape, which is used when painting the body.

The cross-section of the secondary winding wire must be at least 1.8 cm 2. If you can find suitable cable factory-produced insulation, it is better to use it. Both cables with a monolithic core and multi-core cables made from copper wires twisted into a bundle give good results. Several turns of cable or bus are applied to the secondary winding in such a way that when 220V is supplied to the primary circuit, a current of 6-8 V appears in the secondary. In this case, the current strength will reach 800-1000 A. This is quite enough for welding individual parts in a home workshop.

How to choose electrodes

For resistance spot welding, it is best to use industrial electrodes made in accordance with GOST 14111-69. These can be purchased on Internet sites or in welding equipment stores. When used on homemade equipment, they will last almost forever. But they are quite expensive, especially with press-fit tips made of tungsten or other refractory material.

In most cases, craftsmen make electrodes themselves. Depending on the welding power, copper rods with a diameter of 5 to 15 mm are suitable. On one side, they are inserted into a metal sleeve with clamping bolts, fixed to the cable from the transformer. Like the cable, the electrodes are firmly clamped with bolts.

The second option for attaching the electrode is soldering. It is also quite reliable and effective method, providing reliable electrical contact, but changing the electrode in this case is more difficult. This does not affect work productivity too much - the electrodes wear out very slowly, especially during amateur welding.

Much more important reliable contact. If the connection is loose, the wire and electrode will oxidize and overheat, and the current will be less than required. It is also necessary to make all connecting cables as short as possible - the diameter of the electrode and cable must be the same, otherwise there may be surprises in the form of burning insulation or burning of the rods.

It would be useful to recall that the same copper wires are chosen for copper electrodes. Aluminum/copper combinations are unreliable and result in unreliable welding.

The working ends of the electrodes can be pointed (conical), oval or flat. In household homemade devices It is most convenient to use flat bottom and conical top electrodes. This combination will provide high density current at the welding point, and reliable support for pressing the parts.

Battery spot welding

There is information on the Internet about how to make spot welding with your own hands using a regular 12 V car battery. You can use it to make connections small parts, which are usually connected by soldering. But in many cases welding gives best result in strength and more convenient for joining dissimilar metals.

Do-it-yourself spot welding from a battery is a simple design and can be done in the garage within a few hours, if you have all the parts and tools, of course. Its installation does not require any special devices or complex equipment.

There are three types of battery welding. The first, the simplest, one might say primitive, requires only a battery and two copper wires, the bare ends of which act as electrodes. As a rule, this method is used most often, but only for welding non-ferrous metals. It is precisely this that can rightfully be called a point one.

The other two methods - and using an inverter require a battery of several batteries and additional equipment. They are also used in household and hiking conditions, but buying several batteries of the same type to make a welding machine out of them is quite expensive. Any battery that can be removed from the car can be suitable for spot welding.

A simple device for performing welding work consists of two copper wires with a cross-section of at least 1.5 mm 2, fixed in a terminal block. The distance between the stripped ends of the electrodes is 2-3 mm. Of course, as with any homemade design, there can be many options, but as a base it is best to use this type of design. How this mini installation works is shown in the video:

Battery welding is intended for joining small parts made of thin sheet metal, but even then the battery discharges quite intensively. If you removed it from the car, then it is advisable to have it in the garage and Charger to return the batteries to their previous charge.

The examples given are the simplest ones homemade designs spot welding machines. If you have your own developments, write to us on the website. We and our readers are very interested in real developments amateur designers. The most interesting schemes we will certainly publish it.

The inverter is presented on the market in large assortment, where anyone can choose for welding work at home necessary equipment. An alternative option is to make it yourself.

You should familiarize yourself with the design and features of the inverter, the nuances of contact welding, detailed instructions on independent welding work. We will also learn about making a homemade welding device from car batteries and a microwave oven.

Technological aspects of resistance welding

It's not just car enthusiasts and home owners who require welding work. Welding inverter may be required in a small workshop or at home for the installation of metal parts.

The operating principle of the inverter is based on heating the metal from electric current, after which it melts and solidifies to form a weld. To secure the parts to be welded, protecting them from moving apart, you should compress the parts with electrodes through which current is transmitted.

To carry out home welding, you will need power from powerful sources, which can cause household wires to overheat. Therefore, you should first check the quality of the wiring and, if necessary, replace it.

During this process, two workpieces are connected along adjacent edges. This method is used when installing small parts, thin material, metal rods up to 0.5 cm thick.

Options for welding parts

Surfaces can be connected in three ways: continuous or intermittent fusion, resistance. During fusion welding, workpieces or sheets of metal are joined and heated by current until they melt. This technology can be used in the processing of non-ferrous metals, low-carbon steels, installation of steel, brass and copper. But this method is rarely used due to strict requirements for temperatures and the absence of impurities in the connecting zones.

During continuous melting of workpieces, other types of clamps are also used. The parts are connected when the current is turned on. After the edges of the mounted parts are melted, upsetting is carried out and the current supply is turned off. This method is used in the installation of thin-walled pipelines, but it is possible to connect workpieces that differ in structure. The main advantage of the method is the speed of implementation. However, metal may flow out along the welding seam causing waste.

With sequential tight or loose contact, intermittent melting is carried out. Using clamping pliers, the welding line is closed in the area where the workpieces are joined until their temperature reaches 900-950°C. This method is used when the initial power of the device for continuous reflow is insufficient.

As a result of contact welding, the user performs the following work::

All of the listed types of welding processes have a similar technology of work, but differ in the fastening of parts and the current supply.

For household spot welding of parts, you can make the device yourself. The main operating mechanisms in it will be a clamp, a device for supplying voltage to capacitors, in which an electrode is attached to the low-voltage winding. The other clamping wing is a support wing and can be mounted with a part of larger parameters.

Manufacturing a welding device from a microwave oven

As already mentioned, you can make a machine for contact welding with your own hands, where the main part is a transformer from microwave oven. Carrying out similar device, it is necessary to make preliminary calculations of the profitability of such a device in comparison with the purchase of a ready-made inverter.

The most expensive part in homemade device is the transformer, the remaining consumables (base for fastening parts, casing with wires) can be obtained from the repair service.

A transformer should be prepared, the power of which will start from 1 kW, so that welding equipment made from it can connect sheets up to 1 mm thick. If you double the power of the transformer, it will be possible to process sheets up to 1.8 mm thick. In modern microwave ovens, the transformer power can be 3 kW.

To increase the current power, it is possible to use 2 or 3 transformers.

The transformer must be pulled out of the protective casing, the shunts and the secondary winding removed. Due to the high voltage used in a microwave oven, there are fewer loops on the primary winding of the device compared to the secondary winding. To remove the potential difference, we will have to modernize the secondary winding and adapt it for spot welding purposes.

The transformer is thoroughly cleaned of any remaining shunts and secondary winding; if necessary, you can use a long narrow object or a metal brush. That is, the secondary winding needs to be made new, but the primary winding remains in the same form. To do this, you need to take stranded wires, the cross-section of which should not be less than 1 square (due to high voltage future transformer). For the secondary winding, you can make 2-4 turns of wiring (you will get a voltage of 2W), but due to the thick insulating layer it will not be possible to bend it along the coil. Therefore, the wire must be stripped of insulation and wrapped with electrical tape.

When using a circuit of several transformers, the terminals of the secondary windings should be combined. If one transformer is used, then you can use the body of a microwave oven for it and reduce it in length and width.

The casing for several transformers can be made of an iron sheet, covering it with insulating material (insulating tape).

To supply current to the welding area, a lever device is created. Where one lever is firmly attached to the main surface (to make it convenient, the transformer with the casing is also attached with clamps). During lowering, the second lever will press on the parts.

The switch is inserted into the primary winding circuit and mounted on the upper lever, which will help simultaneously pass current and compress the part. In this case, pliers will not be used, but the tips are pre-soldered to the wiring to prevent oxidation.

When resistance welding, copper rods of greater thickness will be used (compared to the dimensions of the wiring). During operation they will be sharpened or replaced.

During operation, the part will be clamped by levers between a pair of electrodes and current will be started.

Production of a welding device from batteries

During welding work with an electric welding device, a high load is placed on household networks. Long periods of spot welding can cause wires to melt or household equipment to break. Therefore, the welding device can be powered by autonomous power supply. For such purposes, a portable generator is suitable, which runs on diesel fuel or gasoline, which you can buy or make yourself.

You will need several batteries from used cars (preferably of the same energy capacity). In this case, the current calculation will be 1/10 of the battery capacity. If batteries of different capacities were used, then the calculation can be performed using the smallest capacity.

A circuit is created from batteries that have been connected in series. Their “cons” and “pros” are fastened with wire cutters, wires or wiring for the cigarette lighter. Any pliers can also be used. The wire is brought out from the free “minus” to the electrode, it is clamped with pliers. A rheostat is installed in the circuit from the free “plus” to the working plate.

Charging equipment can be added to the finished resistance welding equipment.

As a result of analyzing all options self-assembly equipment for spot welding, the availability of this method becomes clear. Thanks to the above information, users can acquire initial spot welding skills and independently make an inverter for resistance welding from existing materials.