Where to find spot welding. Do-it-yourself resistance welding with drawings. Increase the power of the current source

Entrance doors are used to protect the house from temperature changes, noise and unauthorized entry of unauthorized persons. In addition, they are a kind of visiting card of the home, so the owner usually pays special attention to the appearance of the entrance to the building. For the manufacture of modern door leafs, various materials with high strength, minimum thermal expansion and durable fittings are used, it remains to choose the size, type of insulation and the appearance of the door leaf. Consider the types, characteristics, pros and cons of entrance doors, as well as the installation sequence and methods of repairing door leafs for a private house.

Production material of entrance doors for a private house

Distribution networks offer a wide selection of materials from which door leafs are made. When ordering doors for a private home, you must choose the right material for each specific consumer. Manufacturers give products certain properties that allow them to operate in low temperature, high humidity and street noise. The door leaf and the box have certain parameters, which are as follows:

burglar resistance of door frames, panels, hinges and locking elements is divided into six classes of the EU 15, 30, 50, 80, 120 and 180, where the numbers indicate the time required for breaking;
by resistance to shock, static and dynamic loads, doors are classified from M1 to M3;
fire resistance of the door group is indicated in the product passport and has the values \u200b\u200bEI-30, EI-60 and EI-90, where the numbers indicate the time of resistance to an open flame;
according to the heat-insulating properties, the doors are divided into three classes and the highest first class involves the installation of a three-circuit seal and the installation of high-quality insulation;
door leafs should provide sound insulation from 20 dB (1st class) to 32 dB or more (3rd class);
requirements for durability and durability of paint coatings of entrance doors for ferrous and non-ferrous metals of groups 1 and 2.

For the production of doors for a private house, components are used that provide aesthetic appeal and high consumer properties. The complexity of the choice lies in the need to combine all the requirements for door leaves with the preferences of the owner of the home. For example, a wooden house made of timber involves the installation of doors from a pine array, but this design does not give burglar resistance. The metal structure at the entrance to the building does not provide proper thermal insulation, but it is strong and durable. Therefore, combined solutions are used when selecting the components of the paintings, which can minimize the disadvantages of certain types of products. According to the main types of materials used in the manufacture of paintings, entrance doors are classified as follows:

Wooden doors are made of solid wood or planks and, if necessary, reinforced with a metal sheet. The canvas is covered with weather-resistant paint and flame retardant, has good heat-insulating properties and a noble appearance.
Wooden doors give the entrance a cozy look, protect from noise and temperature changes, but are unstable to breaking and moisture
Plastic doors reinforced with a metal frame are equipped with reliable fittings and locks of various types. Such products have soundproofing properties, good heat protection and are not afraid of moisture. Crossbars are built into the door leaf that increase resistance to breaking, and a steel or aluminum reinforced frame provides resistance to static and dynamic loads. Plastic coating does not need special care and painting, doors of this type serve for a long time, keeping their original appearance.
Plastic doors are not afraid of weathering, ultraviolet and have reliable protection against vandals.
Metal doors are the most popular in private housing construction, they have a strong frame and are made of steel sheets with a thickness of 2 to 5 mm, painted with polymer paint, which gives the product high consumer properties. In the manufacture of products, locks with a high degree of secrecy, reliable, durable hinges and additional crossbars are used. Warming is made with polyurethane foam, and the internal decorative finish prevents the formation of condensate.
Steel doors are the most durable, but have poor thermal protection

It is important that the door was made of sheets of metal with a thickness of at least 2 mm with a closed frame and combined stiffening ribs, and also be equipped with three ball or bearing hinges.

Types of Entrance Doors

When choosing products, you need to take into account the characteristics, pros and cons of each type of door and minimize the disadvantages. Consider some of the most popular types.

Doors are street warmed

To improve the heat-insulating properties of the street door, heaters are used located between the ribs, the outer and inner sheets of the door leaf. For this, mineral wool, polystyrene foam and polyurethane foam materials are used. The interior is made of MDF or plastic panels, which prevents the formation of condensation. To increase thermal insulation in modern designs, triple contours of the rubber seal and thermal break are used, which allows to isolate the external, cold part of the door from the inside.

The use of thermal break in the design of the front door significantly improves the insulating properties of the product

The insulated entrance doors of a private house have the following advantages:

high resistance to breaking;
resistance to shock, dynamic and static loads;
reducing the risk of frost and condensation, as well as freezing of the door block due to thermal rupture of the blade and frame.

The disadvantages include the high price of the product.

With large temperature differences, one entrance door is often not enough and cold bridges lead to the formation of condensation and frost on the inner surface of the door leaf. An unheated vestibule from 0.3 to 1.5 m long and a second entrance door mounted on an independent box will help get rid of the freezing effect. In this case, the first design can be insulated with metal, and the second is made of wood or plastic. This arrangement eliminates the sharp temperature drop and improves sound insulation in the living room.

Double entrance doors with unheated vestibule eliminate freezing and street noise

When ordering a double door, you should pay attention to the following circumstances:

the outer door must be insulated, with two sealing circuits and burglar-proof;
the length of the unheated vestibule should exceed 30 cm to create a temperature buffer space;
the inner door must have at least one rubber seal circuit to prevent the entry of warm air into the vestibule.

The advantage of double entry doors is thermal insulation and sound absorption, and the disadvantages are the loss of usable space and considerable cost.

There is an opinion, confirmed by practice, that installing a heat-insulated metal door does not eliminate the formation of condensation, hoarfrost and even ice crust at a significant temperature difference. In winter conditions, the difference between outdoor and home temperatures can reach 60 ° or more. No insulation will provide thermal protection because metal is an ideal conductor. This situation leads to cost overruns spent on heating the home. Arrangement of a warmed, unheated vestibule with a distance between doors of up to 1.5 m will help reduce the difference between outdoor and home temperatures. Losses of usable area are compensated by the absence of freezing and heat loss. The author of the article faced such a problem and was forced to endure the winter, but before the next season he equipped a 2 meter long insulated vestibule. It found a place to store shovels and brooms for clearing tracks after winter snowstorms.

Sliding Entrance Doors

Sliding entrance doors for a private house are glazed or solid closed flaps that can be moved apart or folded in the form of an accordion. For glazing, tempered glass or a durable glass composite is used. The insulated plastic or aluminum profile with rubber seals allows you to reliably save heat and protects against noise. Fashionable modern design saves the interior space and gives the entrance to the house a unique look. The cassette sliding and locking mechanism provides reliable locking of the doors when closed.

The design of the sliding door provides a reliable fit of the door to the opening, and the locking mechanism reliably fixes the canvas in the box

Distinctive features of sliding doors are a modern appearance, a reliable closing mechanism and heat-, soundproofing properties. In the manufacture of used a wide variety of materials and various glazing areas. The undoubted advantage is the simplicity of care and durability, and the disadvantages include the high cost and increased requirements for the cleanliness of the guides in the winter.

According to the author of this article, in a snowy climate of the middle lane, doors of this kind must be mounted with a threshold height of at least 10 cm and on a closed box to ensure structural rigidity. It is also advisable to install an automatic thermal curtain inside the doorway, since when opening the sliding door significant masses of cold air penetrate the opening, which adversely affects the thermal regime of the living room.

Entrance double doors

For convenience, when moving furniture or bulky goods into a living room, double-leaf doors are often used, which consist of two equally or unequal-sized canvases united by one box. One of the wings has strong locks and opens if necessary, and the second serves as a normal door. The design allows the use of double gaskets between the flaps, which provides the necessary noise insulation and thermal protection.

Double doors provide easy access to the building and make it possible to introduce large furniture or household appliances

This arrangement is used for non-standard openings and allows you to increase the useful area of \u200b\u200bthe doors almost twice.

Arched entrance groups are used to adhere to a single architectural ensemble of the entire building or to emphasize its historical roots. In the manufacture of this type of door, various materials can be used, and the difference from other products is in the form of a box and door leaf.

An arch-type door emphasizes the overall architectural design of the designer

Arched entrance doors can be either single or double, often a rectangular door is built into the arched opening, and a fixed semicircular transom is placed above it.

Aluminum Entrance Doors

Entrance doors from the aluminum profile are made in the insulated version of the sandwich panels and, if necessary, double glazing is placed on them, which eliminates the formation of cold bridges. The presence of three or more isolated chambers, as well as a double seal provide thermal break and resistance to low temperatures, plus reliable sound insulation. The thickness of the door is 50 mm and the box 70 mm makes it possible to install crossbars along the entire perimeter, and double-glazed windows made of impact-resistant materials and reliable locks make aluminum structures burglar-resistant.

Lightweight and durable aluminum doors last a long time and do not require special care

The popularity of this type of entrance door is growing from year to year, even in harsh climates they have proven themselves only on the positive side. Aluminum door blocks are fire resistant, durable, not afraid of moisture and ultraviolet radiation, in addition, do not require maintenance and are guaranteed to last at least 25 years. The author recommends paying attention to this relatively new line of practical and lightweight doors for a private home.

Swing doors

Hinged doors are two identical canvases that open in one direction and are mounted in one box of a closed type. Each of the paintings opens independently and is equipped with locking mechanisms and locks.

Swing type doors have two wings, each of which performs the same function

The advantage of this design is its elegant appearance and large opening. In swing doors, pendulum hinges are sometimes used to open the wings on both sides. Convenient and modern swing products have a disadvantage, which includes low resistance to cracking.

The most traditional for suburban buildings are entrance doors made of wood. Products of this type are environmentally friendly, organically combined with wooden walls and protect well from noise and freezing. Wooden paintings are made using insulating inserts, and are also impregnated with fire-fighting and antiseptic compounds.

For a house made of logs or beams, the most suitable is the wooden type of doors that give the entrance to the house a cozy and warm look

The main disadvantages of wooden doors are:

low moisture resistance and a tendency to swell in wet weather;
tendency to warp and low resistance to dynamic and static loads;
low resistance to breaking.

For these reasons, wood is used in the form of decorative overlays for door leafs made of more durable materials.

It is important to remember that even with a flame retardant coating, wooden doors withstand open fire for no more than 15 minutes, and therefore are not a serious obstacle to a fire.

Video: which front door is better to choose

Dimensions of entrance doors for a private house

The dimensions of the doors for a private building are laid at the design level of the building because the designer correlates the dimensions of the entrance group with the overall dimensions of the entire structure. For each building, the size of the doorway can be different, so you need to order individual products for free access to the building or use standard sizes, and cover the rest with transoms and side inserts.

Typical dimensions for entrance doors are 2000 mm high and 900 mm wide. These dimensions provide minimal comfort and are the most popular. At the same time, GOST 31173–2003 for metal doors determines the size of entrance leaves in a height of not more than 2200 mm and a width of 1200 mm. These dimensions are of the single-leaf type without taking into account the dimensions of the box and mounting clearances.

Modern manufacturers of entrance doors, taking into account the wishes of customers, produce door frames of several sizes:

The height of the standard box is 2070 or 2370 mm, therefore, taking into account the installation gap, the opening height should be 2090 mm or 2390 mm, respectively. If the opening is much higher, then stationary transoms or insulated inserts are used.
The width of the entrance doors depends on the size of the opening and the number of wings, but the most common values \u200b\u200bshould be considered 870, 970, 1270 and 1470 mm, a width of 1870 mm is typical for a double-leaf door frame. A number of manufacturers produce products according to individual sizes, but this takes more time. It is important to remember that the installation clearance should be at least 2 cm from the door frame to the opening, and the threshold height, taking into account snowy winters, should not be less than 10 cm from the porch floor.
The degree of thermal insulation and sound absorption, as well as the strength characteristics of the door leaf, depend on the thickness of the door. Given the dimensions of the metal sheet, frame and interior trim, the minimum thickness of the metal door will be 55 mm. Other types of door leafs have similar indicators. It should be noted that the thickness of the entrance doors can significantly exceed the minimum values \u200b\u200band reach up to 100 mm or more, this parameter depends on the wishes of the customer and the requirements for strength, sound insulation and heat-insulating properties of the product.

Front door installation

Self-installation of the front door of a private home implies a certain sequence of actions and requires experience in construction work. Before ordering doors, it is necessary to align the doorway and measure the height and width in at least two places. You should get the wall thickness values \u200b\u200bat four points to determine the parameters of the door frame. In this case, it is necessary to use a tape measure, a building level and a square so that the measurement results are as accurate as possible.

Before ordering the front door, it is necessary to make measurements of the opening, taking into account the installation gap

Then, according to the table, we determine the door size taking into account the size of the box and the mounting gap of 20 mm. For example, the doorway has dimensions 1315x2110 mm, then the door frame should have dimensions 1270x2070 mm, according to the table it is type 21.13.

Table: types of entrance doors with sizes of boxes and canvases

Door type	Box width	Box height	Web width	Web Height
21.7	670	2070	600	2000
21.8	770	2070	700	2000
21.9	870	2070	800	2000
21.10	970	2070	900	2000
21.12	1170	2070	1100	2000
21.13	1270	2070	1200	2000
21.15	1470	2370	1400	2300
21.19	1870	2370	1800	2300

After choosing a door according to the table values, you should make sure of the quality of the product according to the exhibition samples and place an order. For most well-known manufacturers, installation is included in the price and is carried out by a team of masters, but if this is not provided, then the door can be installed independently. To do this, it is necessary to prepare fixing anchor bolts with a diameter of 10 mm according to the number of mounting holes, mounting foam, hammer drill and building level. Installation of the entrance doors of a private house is carried out in the following order:

With the help of wooden or plastic wedges, the door frame is set according to the level and fixing holes are marked on the opening through the eyes.
Holes are drilled under the puncher for the anchor bolts that secure the door frame.
The position of the door frame is regularly checked by the building level.
Anchor bolts are tightened with keys and the position of the box is again controlled by level.
If additional adjustment is necessary, the anchor bolts are loosened and the box is installed in the desired position using wedges
A door is hung on the hinges and its alignment and free play are checked, as well as the operation of the locking mechanisms.
The gaps between the opening and the door frame are carefully sealed with cement mortar and foam.
Closing the gaps with foam allows you to get rid of cold bridges
At the final stage, platbands and other additional elements are mounted.

Based on personal experience installing doors, you can advise involving two assistants who will help with unloading and, most importantly, in adjusting and centering the box at two levels in different planes. This will make it possible to achieve an ideal door position, in which it will not spontaneously close or open. A reasonable distribution of responsibilities reduces the installation time of this element of the entrance group to three hours on a turn-key basis.

Video: do-it-yourself front door installation

Repair and restoration of entrance doors of a country house

During operation, the entrance doors are subject to wear and natural aging, so there is a need for repair and restoration of individual parts of the input unit. When diagnosing, you can understand the cause of the wear of the door elements and determine the malfunction that can be fixed on the spot or only in the factory.

Possible malfunctions of door structures

The main breakdowns during operation have the following reasons:

shock loads on the outside of the door or interior trim elements;
skewed door frame due to shrinkage of the supporting structures of the house;
failure of hinges or locking mechanisms;
damage to the insulating layer and sound insulating pads;
corrosion due to violation of the integrity of the paintwork.

Tools and materials needed for repairs

For repairs, you may need the following tools or materials:

electric drill and cordless screwdriver;
a set of bits and screwdrivers;
building hair dryer and grinder;
glue, brushes and spray;
chisels, spatulas and scrapers;
metal brush and sandpaper;
grease.

Do-it-yourself door repair and restoration

After determining the cause of the malfunction, the following operations must be performed to eliminate the defects:

Elimination of shock loads on door elements is carried out by eliminating dents or damage, sometimes it is necessary to replace decorative overlays.
When the walls of the building shrink, it is necessary to remove the canvas from the hinges and, using the adjustment, eliminate the skew and restore the geometry of the door frame, in this case, the deformation of the load-bearing walls will not have a significant effect on the door block.
Locks can be repaired on their own by replacing the locking mechanism
The loss of thermal insulation properties of the door is eliminated by the complete or partial change of mineral wool. Expanded polystyrene, as a rule, serves for many years and does not need repair.
Insulation repair is carried out by replacing the insulation material
Corrosion can be eliminated by removing old paint, cleaning and degreasing the damaged surface and applying new paint with a suitable color.

The author of the article recommends determining which damages and malfunctions are an insured event and must be repaired at the expense of the supplier, and which ones the owner must fix independently. Often the failure of the locking mechanisms or poor-quality coloring of the doors is a consequence of the negligence of the manufacturer.

Finishing the front door of a private house

Finishing the front door is external and internal, and over the years of service may require replacement of decorative panels. The need to update the interior decoration may be due to damage or repair of the hallway, which will require a change in the finishing material on the panel of a different color scheme.

Finishing materials for the front door are diverse and will satisfy the most demanding client

The following finishes are available:

replacement of paintwork with a different color scheme during repair;
decorative inserts or forged metal plates;
finishing with an array of precious wood or veneered panels of noble varieties of wood;
finish with MDF panels or laminate.

To restore the finishing material, it will be necessary to remove the door panel from the hinges, dismantle the old coating, clean and degrease the canvas and fix the new coating on the door or paint.

We talked about the most popular types of entrance doors for a private house and analyzed their characteristics, positive and negative sides. The sizes of standard boxes manufactured by manufacturers allow you to install them in various openings with your own hands without significant alterations. Repair, restoration and decoration of door leafs can also be done independently with a minimum set of tools and equipment. Video material will help you choose the right front door for your home and install it.

Many do not want to depend on circumstances. If you suddenly need welding, you want to solve the problem in your workshop. DIY welding machine is the solution in the right direction.

To perform resistance welding with your own hands, you need to purchase or make a special machine yourself.

Of course, if you need to weld large metal structures, then contact welding is difficult to compete with other types. At the same time, at home, there is a great need for welding small parts. Such tasks become easily solved if you make your resistance welding machine.

Resistance Welding Basics

In the general case, resistance welding is welding using electric current when it passes through the contact zone of the metals being welded under the action of compressive pressure. The principle of contact welding is based on the fact that at the moment of supply of electric current in the place of contact of two metals arcs arise, which melts them. The duration of the welding current is very short (0.01-0.1 s). The main parameters of any contact welding are: the strength of the welding current, the time of application of the current and the magnitude of the compression of metals in the contact zone. There are the following main ones: spot, relief, seam and butt welding.

Basics of designing apparatus

To conduct resistance welding, it is necessary to assemble a resistance welding device. In the manufacture of apparatus and devices, several basic rules must be taken into account. Typically, for household purposes, devices of spot or butt welding are used. Then you should think about whether the device will be - stationary or portable, which determines its weight and dimensions. It is necessary to determine the main parameters of the device:

Type of welding current (alternating, constant) and its strength.
Voltage in the weld zone.
The duration of the welding pulse.
The number and type of electrodes.
The simplicity of the apparatus.

Any resistance welding machine contains electrical and mechanical parts. The electrical part includes a welding current source, a control system for the main parameters and a contact block. The mechanical part must ensure the fastening of the welded workpieces, as well as the application of a compressive load.

Welding current source

The main element of the resistance spot welding apparatus is the welding current source, i.e. short current pulse. The most common current sources using energy storage and discharge capacitors. One of the simple schemes of such a source is based on the supply of direct current from the secondary winding of the transformer, to the primary winding of which the capacitor is discharged (Fig. 1 is a diagram of the power source).

Figure 1. Power supply circuit.

The primary winding of the output transformer T2 is connected to the input electrical network so that one branch of the circuit passes through the diagonal of the rectifier bridge (diodes V5-V8). In this case, the control is carried out through the thyristor V9, connected to the start button "Impulse", due to its connection to the second diagonal of the bridge. The accumulation of energy is carried out in the capacitor C1, located in the circuit of the thyristor V9 and connected to the diagonal of the bridge. The discharge of the capacitor through this circuit goes to the primary winding of the output transformer T2. The capacitor C1 is charged from the auxiliary circuit, the connection of which occurs when the main circuit is turned off.

Such a welding pulse source operates as follows. Capacitor C1 is charged when the output transformer T2 is disconnected. When the “Pulse” start button is pressed, the capacitor charging stops and its discharge to the adjustable resistor R1 connected to the primary winding of the transformer T2 takes place. The discharge parameters are controlled by the V9 thyristor. The duration of the welding pulse is controlled using a variable resistor R1, to which the discharge occurs. When the button is turned off, the capacitor charging process resumes.

Recommended details for the circuit: C1 capacitor with a capacity of 1000 microfarads for operating voltage up to 25 V; thyristor PTL-50 or KU202, input transformer T1 with a power of 10 W for a voltage in the windings 220/15 V. It is better to make the output transformer T2 with your own hands: the primary winding is PEV-2 wire with a diameter of 0.8 mm, 300 turns; secondary winding - copper busbar 20-25 mm², 10 turns. The output parameters of the device: current strength up to 500 A, pulse duration up to 0.1 s.

Increase the power of the current source

Figure 2. Diagram of a source of increased power: 1. schematic diagram; 2. winding of transformer T2; 3. starter connection diagram.

To increase the power of the welding pulse, you can make some changes to the device. The current is supplied through a contactless magnetic starter type MTT4K (operating current up to 80 A). 2 thyristors (Fig. 2), 2 KTs402 diodes and resistor R1-R2 are introduced into the control circuit. The response time is controlled by a RES timer. As energy storage devices, a capacitor bank C1-C6 of 6 pieces is recommended (Fig. 2 is a diagram of a high-power source: 1) circuit diagram; 2) winding of transformer T2; 3) starter connection diagram).

It is recommended to install the following parts: C1-C6 electrolytic capacitors with a capacity of 47 microfarads, 100 microfarads and 470 microfarads (two of each type) for an operating voltage of 50 V; a relay timer RES42 or RES43 for a voltage of 20 V. The transformer T2 has a primary winding from a wire with a diameter of 1.5 mm, a secondary winding from a copper bus bar with a cross section of 60 mm² (the number of turns is 4-7). The welding current of such a device is up to 1500 A.

Output Transformer Fabrication

One of the most important elements of the equipment is the output welding transformer. Its manufacture should begin with the selection of a typeset core. A standard core with a total cross-section of at least 60 cm² should be used. The coupler of type-setting elements is made using a corner or strip and is fixed with bolts with a diameter of 8 mm. The primary winding is wound manually with PET or PETV wire on one side of the core. The turns are evenly distributed along the length of the core. The ends of the winding are displayed on the panel and fixed in the connection block. The secondary winding is made on the second side of the core from a copper bus. Pre-copper busbar is insulated with PTFE tape or fabric tape. At the ends of the bus outward, holes are drilled for bolting the cable. An insulating layer is applied over both windings.

Contact block design

The simplest contact block device involves supplying current directly to the parts to be welded. This method is used in butt welding. Crocodile clips are used to ensure contact.

A more complex system involves the direct connection of current only to the most massive part. The second contact is provided by a movable upper electrode, which is supplied to the welding zone manually. As such a contact, a welding gun can be recommended. It is made of two identical textolite plates carved in the shape of a gun. Nuts are installed in the front part for screwing a copper electrode into them; in the central part there is a start button. From above, a cable is inserted into the device, which is connected to the electrode, and a wire from the primary winding circuit of the transformer, which is connected to the start button.

The plates are fastened together so as to securely fix the electrode mount.

Apparatus assembly

Figure 3. When assembling the welding machine, an input cable from the mains is attached to the terminal block, which is located on the electric plateau.

The welding current source is placed in a metal housing. The electric plate is assembled on the PCB and fixed inside the source casing, usually vertically. The output transformer is mounted on the base of the housing. From above, a welding cable is attached to the bus of the secondary winding of the transformer, the second end of which is connected to the electrode in the contact gun. An input cable from the mains is attached to a terminal block located on an electric plateau (Fig. 3).

Tools and auxiliary tools that are necessary in the manufacture of a resistance welding machine with your own hands:

bulgarian;
electric drill;
hacksaw for metal;
file;
chisel;
hammer;
pliers;
screwdriver;
vise;
calipers;
scissors;
tap;
dice.

It is not difficult to make a resistance welding machine. You can choose a very simple design, or you can make universal equipment.

Among the many types of welding processes, one can single out a point one. It is used to create ventilation and air conditioning systems, to connect thin-walled body parts and many other designs.

Types of spot welding

One type of contact welding is referred to as spot welding, during the course of which parts are connected at individual points. Electrodes made of different materials compress the workpieces and transmit the electric current of the corresponding characteristics through themselves. The location of the contact points directly depends on how the electrodes are installed in the machine used for welding. Again, depending on the design of the machine and the electrodes, one or more welding points is acceptable.

Resistance welding is used to work with ferrous and non-ferrous metals. These can be parts machined on mechanical equipment, they can have the same or different thickness. As blanks, sheets obtained on rolling mills or forging equipment can be used.
This type of welding is most effective for the manufacture of parts in transport engineering, in the production of machine tools of various classes, etc.

Features and principle of spot welding for the choice of transformer

The spot welding method is used both at production sites and in artisan workshops. In production, this technology is used to work with sheet billets of different metal grades - black, non-ferrous, non-rust, etc. Parts of different shapes and sizes are processed using spot welding, in addition, intersecting rods are made on such welding equipment.

In the home workshop, this technology is used to repair household appliances, including automotive, electrical, for example, to build up a power cable.
It should be noted that the method of spot welding includes several sequential operations, moreover, these operations are the same for both industrial and domestic equipment.
At the first stage, billets made of metal are interconnected in a given spatial position. For their fixation, ordinary construction clamps or other technological equipment can be used.

Then, the connected parts are placed in the working area of \u200b\u200bthe equipment, in the space between the electrodes. After that, they are set in motion, the compression of the workpieces and the supply of electric current with certain characteristics begins. The supplied current performs the heating of the metal to a certain temperature, as a result of this, the necessary deformation of the workpieces will be produced.
In industrial conditions, automatic spot welding machines are used; in workshop conditions, semi-automatic welding machines are more often used. Some types of equipment allow you to get up to 600 welded contacts per minute.
Another method of spot welding is laser. Its application provides high quality, obtained seams.

The meaning of welding of this type is as follows:
After strong heating of the workpieces, they are melted and a homogeneous structure (weld) is formed.

The main parameter of such a welding process is the impulse current characteristic.

It is she who provides the required heating. In addition, the force with which the workpieces are pressed against each other plays an important role. It is as a result of this that crystallization of the metal structure occurs.
Pulse welding guarantees maximum joint strength, with almost complete automation of the welding process. But the main drawback of this technology is the inability to ensure 100% tightness of the blanks among themselves.

Types of transformers for welding

Technical characteristics of transformers should provide such technical properties that allow heating, melt and joining of workpieces with minimal losses.

The transformer, designed for welding, has a simple design and that is why many home craftsmen prefer to make it on their own.

The design includes several components:

A core consisting of several plates made of steel. To assemble the magnetic circuit, plates made of electrical steel are used. One or more windings are installed on it. The voltage is adjusted using a screw pair, which passes through the core and the winding.
The metal case is designed to protect the device from any damage. In addition, the transformer includes ventilation devices, handles and wheels for transportation.

The rated operating voltage is 220 or 380 volts and this allows them to be used both in industrial facilities and in the household. The technical characteristics of the transformer allow you to work with metal blanks of various shapes and sizes.

The transformer for resistance welding, consists of the same units as for traditional. This equipment operates in short, but often repeated loads. This leads to the fact that the windings experience serious dynamic loads. To compensate for them in spot welding transformers, an armored type core and disk windings are used.

The resistance welding transformer TVK-75 is designed to operate as part of electric spot welding equipment that are operated in enclosed spaces under a number of conditions. The magnetic circuit in this transformer has a tape design, and is pulled into the frame with the help of studs. The windings of this transformer are disk. For the manufacture of the first winding, a heat-resistant PSD cable is used.

The second winding is assembled from separate disks and with the help of metal parts made of copper, they are assembled in parallel circuit.
To cool the secondary winding, running water is used, which moves through specially laid pipes. The windings are filled with epoxy resin.
The voltage is regulated using switches that are installed on the welding machine. The main parameters of the transformer of this brand include the following:

Water-cooled, the device is manufactured in insulation class F. Due to the use of Unicore technology, the transformer has minimal losses in the magnetic circuit. The manufacturer produces a transformer in the climatic version UHL4.

Transformer for resistance welding TKS - 4500 Cascade

Resistance welding transformer TKS - 4500 Cascade is used for welding parts from low carbon steels with an aggregate thickness of up to 4 mm.

Calculation of the transformer for welding

The magnetic core and windings are responsible for creating the operating parameters of the device. That is, knowing what characteristics the transformer should have, you can calculate the parameters of the windings, core and cross-section of all wires.

To perform the calculations, you need to take the following data:

1. Voltage on the first winding.
2. Voltage on the second winding.
3. Current strength on the second winding. The size of this parameter is determined by the type of electrodes and the size of the workpiece.
4. Core area. This parameter determines the reliability of the transformer as a whole. The optimal size can be considered from 45 to 55 square meters. cm.
5. The size of the area of \u200b\u200bthe core window. The optimal size is from 80 to 110 square meters. cm.
6. Current density inside the winding. This parameter is responsible for winding loss. For self-made devices, this characteristic is 2.5 - 3 A.

Homemade microwave oven

To install high-performance welding equipment in your home workshop, you do not need to purchase expensive equipment. To do this, just use the old microwave. More precisely, her transformer. He is able to provide the voltage necessary to perform spot welding.

Care must be taken when removing the transformer from the microwave oven housing. First you need to remove all the fasteners, and remove the secondary winding. In addition, shunts built into the current limiters must be removed. Spot welding, made from a microwave oven, provides a power of 700 - 800 W and this allows welding of steel sheets up to 1 mm thick.

As with any other welding device, an electrode is required to operate it.

Making electrodes

Welding equipment allows you to perform a large number of works on the inseparable connection of parts made of metal. To perform this operation, electrodes are used. Those that are used for spot welding are called welding pincers. You can buy them in a specialty store, or you can make them yourself.

Welding pliers consist of:

a gripper that carries current carrying parts;
actually electrodes;
welding cables;
control mechanism.

For a high-quality welded joint, it is necessary that at the outlet of the apparatus there is a stable low voltage and high current strength. Often, to achieve the necessary parameters, devices with a reinforced second winding are used.

The voltage from the winding is supplied to the welding tongs, into which the workpieces to be welded are inserted.

When the workpieces are assembled together and placed in the working space, the electrodes are compressed. This can be done manually or in automatic modes. At the same time, a current of proper power is supplied to the electrodes. It causes the heating of the metal, its melt and mixing. So, resistance welding is carried out. The diameter of the contact spot determines the size of the current and the exposure time of the parts between the electrodes.

Non-ferrous metal spot welding

Non-ferrous metal spot welding is widely used in industry. An example is aluminum welding. An important point in spot welding is the removal of oxide film from the surface of the workpieces. As a rule, it is removed using a steel brush or abrasive skin of zero size. Another, no less common way to remove the oxide film is a chemical one.

For this, sulfuric or chromic acid is used. But, this method is used in mass production.

For welding non-ferrous metals, in particular, aluminum, it is necessary to use machines of high power. So, for welding two sheets of duralumin with a thickness of 0.5 mm, a current of 12,000 A will be required.

One of the varieties of resistance welding is condenser. This welding method has been known since the first half of the last century. Welding occurs due to the melting of the workpieces in those places where a short circuit occurs, which is obtained from the discharge energy of capacitors. The welding process takes 1 to 3 milliseconds.

At the heart of such a welding machine is a capacitor bank charged from a constant voltage source.

Upon reaching the required amount of energy in the capacitance, the electrodes close at the welding site. The current flowing between the workpieces causes the necessary surface heating and as a result the metal melts and a high-quality weld is formed.

The advantages of capacitor welding include:
Speed, the use of automated equipment allows you to get up to 600 points of welding per minute. Precision positioning and joining workpieces. Low heat generation, lack of consumables - wire or electrodes.

In practice, two types of devices of this type of welding are used. The former provide a discharge from energy storage devices on the surface of the parts, the latter receive a discharge from the second winding of the transformer. The first method is used when performing shock-capacitor welding, the second is used when it comes to the need to obtain a high-quality weld.

Such welding is economical and therefore it is often used in a home workshop. On the market you can find devices with a power of 100 - 400 W, which are often used to work in small workshops for the repair of automobile bodies.
Duration of heating and pressure
Welding modes are determined by the following characteristics - current strength, duration of heating, compression force, dimensions of the working end of the electrode.

Features of the selection and use of electrodes

The electrodes for such welding should have a shape and size that will ensure its access to the workplace. In addition, the electrodes must be adapted for simple and reliable installation in the welding machine and have high wear resistance. The simplest spot welding electrode design is straight. They are produced in accordance with the requirements of GOST 14111-69. Various copper-based alloys are used for their production.

For example, when welding different metals, the electrodes should have low electrical conductivity. But if, from the metal of this type to make the entire electrode, it will quickly heat up. In this case, it must be performed in two parts. One of copper, and the other of a material that is adapted to perform the necessary operations.

The spot welding machine is very easy to manufacture. It comes in many different configurations - from small portable to fairly large. Before proceeding with the assembly of the construction of a home-made apparatus, recall the Joule-Lenz law, which gives a quantitative estimate of the thermal effect of electric current (Q \u003d I² X R X t). Given that the amount of heat released in the conductor is directly proportional to the resistance of the conductor, the current strength in square terms and time, poorly made connections with thin wires will lose 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?".

Because of 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 more 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. The spot welding machine is a type of contact welding, which is why its technology is based on the thermal effect of electric current.

Brief spot welding technology

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

The need for pressing parts is explained by the formation of a sealing belt around the molten core. At the moment of the welding pulse, the formed band prevents the molten metal from splashing out of the welding zone.

Next, you should heat the parts 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 connected parts.

A spot welding machine heats parts thanks to a short-term pulse generated by the passage of the welding current. This impulse contributes to the melting of the metal in places of contact with the electrode, forming a common liquid core of the parts. The diameter of the formed core reaches - 4-12 mm.

As soon as the current stops, the parts will continue to be held until the molten core cools down and crystallizes. The technology of spot welding at home is very economical and is able to provide mechanical strength of the seams. As for the tightness of the seam, this equipment cannot be achieved.

Welding processes, equipment used, as well as safety measures are strictly regulated by GOSTs. You can familiarize with some of them:

GOST 5264-80 and GOST 11534-75 designed for manual welding;
GOST 10157-79 and GOST 5583-78 regulate technical conditions;
GOST 15878-79 governs the structural joints of resistance welding;
GOST 2601-84 (metal welding, basic concepts);
GOST 19521-74 - Welding of metals and classification.

Home-made spot welding machine design

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

To make welding equipment according to this scheme is quite simple. The main component of the equipment is the T2 welding transformer. The welding electrode is connected to the secondary winding of the transformer using a flexible cable. As for the more massive weldment, it connects to the lower end.

The welding machine is connected to the network using the rectifier bridge V5 ... V8. The second diagonal of this bridge is provided for turning on the thyristor V9, when it is opened, voltage is applied to the primary winding T2. In this case, contact welding tongs act as a gun. Their technological feature consists in connecting the gun to one end of the secondary winding of the transformer, as for the second end, it is attached to the product of spot welding. Thus, the pliers can perform welding work anywhere in the product using a single electrode. Resistance welding pliers can operate on single-phase or three-phase current. The transformer, from which the tongs for resistance welding is powered, produces a current of several kilos Amperes.

In the handle of the welding gun is a button S3, when pressed, the thyristor is controlled. When connecting an auxiliary source to the network, charging of capacitor C1 immediately begins. The transformer T1 and the rectifier bridge V1 ... V4 are an auxiliary source.

Detailed point device diagram

The welding machine T1 is turned on by closing the diagonal of the bridge V5 ... V9 with the opened thyristor. The thyristor will remain open until the capacitor C1 is completely discharged. A variable resistor R1 is provided for adjusting the discharge time of the capacitor. To prepare the next welding pulse, the button S3 must be released, at this time the capacitor C1 is charged. A subsequent impulse is formed by repeated pressing.

Transformer T1 can be any low-power (5 ... 10 W). The maximum duration of welding, with the indicated ratings C1 and R1, will be 0.1 seconds. This provides a welding current of 300 ... 500 A, which is quite sufficient for welding small parts.
In this example, the transformer is made of iron. The thickness of the set is 70 mm, the wire PEV-2 0.8, 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, it is necessary to bite the copper bus and remove the secondary windings from all coils. The primary wiring remains intact, and the middle one must be rewound with the same wire, forming bends every 30 turns. There should be 8 to 10 of them.

Using a three-phase power multicore cable, wind the secondary winding on the two extreme coils until they are full. The cable should consist of wires D - 6-8 mm., And one of them should be thinner. It is reliably insulated and able to withstand high currents. Due to the flexibility of the wire, winding can be done 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 wires must be folded in half.

It will be difficult to cope with such a task alone. It is recommended to do the work together: one stretches the wire, the second lays the turns. For the manufacture of clems, you will need a copper tube D - 10 - 12 mm and a length of 30 - 40 mm. One side of the tube needs to be riveted, in the resulting plate, drill a hole D - 10 mm. The wires are inserted on the other side, which should be carefully stripped. With a hammer, it is necessary to crimp the stripped wires. To improve contact on the surface of the tube, notches must be made.

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

Here is such an aesthetic look, it can have, spot welding assembled by yourself

A 3/4 pipe with a length of 250 mm acts as an electric holder, on both sides of which notches are cut. 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 in the secondary winding is connected. The pipe must be covered by a rubber hose of a suitable diameter.

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 multipoint welding machine, in contrast to a spot welding machine, works with workpieces of certain sizes and shapes. Universal multipoint resistance welding machine is quite rare. The readjustment of this unit is a rather complex and lengthy process.

Spot Welding Electrodes

No resistance welding can be carried out without a specific welding attribute called resistance welding electrodes. For spot welding, special electrodes are used, which are made of alloys with high thermal conductivity. The electrodes perform the function of compressing the metal and supplying current to the product. The thermal concentration during spot welding depends on the tip, so a very thin tip is subject to rapid wear and requires constant grinding. The most common tip shape is the cone. In order for the electrodes to last for a long time, the following conditions must be observed:

Do not use thin tips for heavy welding;
Use specially designed electrodes for a specific material;
Use a water shirt;
Store electrodes in places where they will not get damaged;

DIY spot welding can be a very necessary machine in the home workshop. Such a device allows you to connect various metal elements, repair different designs at home. And most importantly, hand-made manufacturing helps to avoid significant costs associated with the purchase of finished welding devices.

Do-it-yourself spot welding is a rather complicated design and to create it you need certain skills in electrical and plumbing, but for all the complexity you can safely get to work, armed with knowledge of the principles of installation. Home craftsmen came up with different schemes and manufacturing technologies, which were implemented and tested in real conditions. Positive reviews on the performance of the devices indicate the possibility of assembling sufficiently reliable structures.

The main essence of the process

Spot welding is a type of contact welding, i.e. It is a combination of metals by the penetration of their melts into each other during point contact under load.

The principle of the implementation of such a process is based on the fact that the connected workpieces are tightly aligned and are pressed from both sides by electrodes, to which a short-time welding current is supplied.

Due to the intrinsic electrical resistance during the passage of a large current, the materials are heated to their melting temperature, and the melts of the two billets are mutually mixed under load, which ensures a strong connection.

To reduce the heating zone (reduce the required power of the welding pulse), a minimum contact area is provided - point type electrodes are used.

Apparatus construction

The spot welding machine includes two main parts - the source of the welding pulse and the contact block. The power source must provide a pulse in an automatic mode with a current strength of about 150-250 A for 0.02-0.1 s when powered from a conventional mains voltage of 220 V. A desirable condition is the ability to control the current for welding workpieces of various thicknesses and from different metals.

The following requirements are imposed on the contact block: summing the welding signal using a point electrode, pressing the welded workpieces, holding the workpieces until the melt completely solidifies after the pulse has been removed. Basically, such constructive solutions are used: clamping workpieces between two point electrodes; one electrode is flat and the other is point; spotter - the workpiece itself plays the role of the lower electrode.

Essential tool

To make a DIY spot welding machine, you will need the following equipment and tools:

welding machine;
bulgarian;
electric drill;
hacksaw for metal;
milling cutter;
soldering iron;
file;
chisel;
hammer;
pliers;
screwdriver;
scissors for metal;
calipers;
metal ruler;
spanners.

Power Supply Fabrication

A home-made spot welding machine is usually assembled on the basis of a welding pulse source using the principle of a capacitor discharge. A simple diagram of such a source. A welding machine with such power is capable of welding a sheet up to 0.5 mm thick; it can be used for batteries with the goal of reliable connection of Li-Ion batteries.

The necessary current in the form of a short-term pulse is created at the output of the secondary winding of the transformer Tr3, while the desired signal is provided by the discharge of capacitors C8-C9 to the primary winding. Thyristors T1 and T2 provide capacitor discharge control. The accumulation of charge on the capacitor plates is carried out when the auxiliary circuit of the current transformer is switched on. To rectify the electric signal, diodes D6-D7 are used.

The principle of discharge of capacitors is as follows. In the period of the disconnected main circuit, the capacitors C8-C9 are charged through the Current winding. When the main circuit is turned on (welding machine start), the capacitors are discharged to the Tr3 winding, while the discharge parameters are regulated by T1-T2 thyristors, and the signal duration is provided by the Ru1-Ru2, R34 and C10 systems. The cycle is completely repeated when the device is turned off. Recommended characteristics of the parts are given, and the parameters of the transformer Current are as follows: type 220/220 V, PEV-2 wire with a diameter of 0.5 mm is used for both windings, the number of turns is 90.

For welding workpieces up to 3-4 mm thick, the discharge power should be increased. A diagram of a more powerful current source is given, which, according to the principle of operation, does not differ from the previous case. The pulse duration is regulated by a time relay, and the MTT4K contactless starter is connected to the primary winding of the output transformer, due to an increase in power.

Winding power transformer

The output transformer is a fundamental part of the entire design of the apparatus for welding, providing the necessary amperage supplied to the electrode. It is desirable to do it yourself as follows. The core is suitable for an ordinary transformer that is out of order - it is important that it has a steel plate design and has a total cross section of one element of about 65 cm².

The primary winding of PEV or PETV brand wire with a diameter of 2.9 mm with a number of turns of 20. is wound on the first rack. Transformer (cable) paper is applied under the winding and on top of it. The ends of the winding are fixed on a terminal block located on the upper part of the core.

An output (secondary) winding in the form of two turns of a flat bus is wound on the second pillar of the core. Such a bus can be assembled from 15-17 copper flat wires with a total cross-section of 200 mm² and wrapped for insulation with fluorine film or fabric insulation tape. It is recommended to lay transformer paper on the top and bottom of the winding, and put the ends of the winding on the terminal block.

If all of the above conditions are met, then an output transformer with the following parameters should be obtained: power 3000 V A; primary voltage - 220V, secondary voltage - 15V, current - up to 220 A.

Contact Block Assembly

For a home spot welding device, incl. spotter, the most commonly used unit design is for pistol-shaped contact. The gun for the electrode is assembled in this sequence. Two plates of getinax or textolite 8-12 mm thick are selected, from which figures are cut out in the form of a pistol 23-25 \u200b\u200bcm long. The shape is arbitrary, taking into account the ease of use. It is advisable to provide the following geometry: barrel width - 42-45 mm, handle width 50-55 mm, handle length - 100-110 mm.

In the front part of the halves (trunk), symmetrical longitudinal semicircular grooves with a radius of 5-7 mm are made to install the electrode. The length of the bore channel is 55-60 mm. At a distance of 30-35 mm from the extreme section of the trunk, a rectangular groove is machined on the longitudinal groove to install the nut, into which, then, the electrode will be screwed. In the trigger section, sampling is made and a hole is drilled for mounting and fastening the trigger push-button switch. To align the two halves of the gun, holes are drilled for the screws: in the handle - 4 pieces, in the barrel and in the back - 2 pieces. To ensure cable entry, grooves are made in the handle and between the trigger and the electrode channel.

The electrode is made of a copper rod with a diameter of 8-10 mm, and a thread corresponding to the fastening nut is cut at its tail end. The front end of the rod is sharpened in the form of a cone of the order of 15-20 mm, and the top of the cone is rounded off. The total length of the electrode is selected on the order of 50-60 mm.

The welding gun is assembled in the following order. A nut is screwed onto the tail of the electrode, and a lead wire that is connected to the start button is soldered to its end. In the trigger part, a push-button switch is laid with the output of the button in the hole. The button connects to the electrode, and the lead wire is connected. The whole scheme fits into the corresponding grooves and grooves; the pistol halves are aligned and twisted.