How to make resistance welding pliers

Details about self-assembly of resistance welding pliers

Homemade contact welding pliers - device and principle of operation! The most common method of joining and cutting metals is welding. There are different options for welding work, which depend directly on the materials and equipment used. To work with small products, a contact connection method was developed, the essence of which is to heat the metal using an electric current.

Current is passed through the metal in a specific welding zone, connecting the products to each other. Preliminary preparation of the surfaces to be joined, the strength of the electric current, the duration of exposure of the current to the place where the metal is joined, as well as the compression force of the parts being welded are the main factors affecting the quality of welding work.

The most compact and lightweight device for this type of joining of metal surfaces is resistance welding pliers.

Miniature resistance welding pliers

Operating principle and design of resistance welding pliers

According to the method of operation, there are two types of pincers for contact connection of parts:

Hand pliers for a resistance welding machine are a device consisting of a transformer to which pliers for electrodes are attached. At the top of the body there is a lever that performs the function of adjusting the opening width of the holders. To operate the device, it is not necessary to connect the electrodes via wires to a separate current source. These welding guns are very convenient to use, as they weigh only 12 kg.

When connected to an electrical outlet, hand pliers generate a welding current that is supplied to electrodes that clamp metal workpieces. The metal melts under the influence of the welding current, and a welding point is formed at the clamping point. The impact of the electrodes on the metal on both sides provides good clamping, which results in a more reliable connection compared to one-sided spot welding.

Hanging pliers are most often used in industrial process environments. Their main advantage is considered to be high productivity, which determines their use in various areas of modern production.

Device for joining thicker metal

Welding pliers selection parameters

When choosing manual resistance welding pliers, pay special attention to the maximum current value. The higher the current value, the greater the thickness of the part that can be connected. For a clear example, you can take hand pliers with a current of 3800 A. Using them, we can connect two sheets 1 mm thick. The maximum value of such devices is 6300 amperes. These characteristics allow you to work with sheets up to two millimeters thick each.

An important indicator is the overhang of the electrodes; it is also called the length of the brackets. Electrode extension is the distance from the pliers body to the electrode. The maximum permissible distance from the edge of the sheet at which a point connection can be made depends on this indicator. The length of the brackets, depending on the device model, ranges from 120-500 mm.

Electrodes for resistance welding

No resistance welding can be performed without a specific welding attribute - resistance welding electrodes. The most popular electrodes for contact connection of parts are straight electrodes. They are made from rods with a diameter of 12-40 mm.

The tails of electrodes for contact welding are of both cylindrical and conical types. They are fixed in the handle socket using special clamps or conical threaded connections. Welding electrodes with a replaceable working part are secured using a union nut.

Electrodes for resistance welding are made mainly based on copper alloys. Copper is alloyed with chromium, cadmium, beryllium, cobalt, etc. Due to their low electrical resistance and heat resistance, such electrodes do an excellent job when in contact with the surface of the part being welded.

The entire installation is assembled

Homemade resistance welding pliers

The step-by-step process of assembling spot welding pliers with your own hands will require a little effort and patience. For this we need a copper dart, 2 m long and 30 mm in diameter. The dart can be a little longer so that it can be bent well. We bend it so that we get the letter U. At each end we make one hole with a diameter of 18 mm, unfold them and make a cut.

Thus, we will have two clamps for the working electrodes. Next, we connect two transformers in parallel, in which the primary and secondary windings are connected directly, with a voltage of 9 amperes. Adjust the current supply yourself. For example, you can solder a triac switch with an ordinary standby multivibrator, which will work out the shutter speeds. Cooling of homemade ticks is done with water.

The electrodes are removed using a foot pedal.

So, manual welding pliers consist of a transformer, a lever that turns the electrodes, and a handle with a pusher. The lever and handle are held by hinges, the axes of which, during operation, are opposite. Some types of pliers have a spring between the pushers. Such pliers are not entirely convenient, since it becomes more and more difficult to compress the spring with any rotation. Every element of the installation is very important. If any component fails, the entire system will collapse.

Source: http://zavarimne.ru/oborudovanie/podrobno-o-samostoyatelnoj-sborke-kleshhej-kontaktnoj-svarki/

Welding pliers. We connect metal in one touch

For resistance welding, an important factor is the geometric accuracy of the location of the welded joint. This, as well as a number of other functions - for example, the convenience of fixing workpieces - are successfully performed by welding pliers. Today, we will tell you about the operating principle and criteria for choosing this tool.

Design and types of pliers

Manual welding guns for resistance welding include:

1. The housing in which the equipment in question is connected to the welding transformer.
2. Swivel arm with clamp for top electrode.
3. Bottom electrode clamping unit.
4. The handle on which the controls are mounted. For more powerful standard sizes of pliers, pedal activation is provided. The second, side handle is designed to hold the tool during welding.
5. Monitoring and control system based on various types of relays - welding current interrupters.
6. An extension cord or apron if you need to carry out welding work at some distance from the transformer.

Although the electrodes are not included in the kit, all technical characteristics of the welding pliers produced are based on a specific type and diameter of the consumable.

The presence of such a tool significantly reduces the labor intensity of welding, since when working in different places, there is no need to move a massive welding transformer.

This is why resistance welding pliers are especially popular in auto repair shops that perform body repair work.

Welding pliers are classified according to the following criteria:

• By installation method. Hanging pliers are popular for industrial resistance electric welding in large volumes, while manual, more compact ones are better for welding in hard-to-reach places.
• By electrode clamping drive, which can be manual or pneumatic.
• According to the drive principle. Automatic pliers are triggered by a control signal from a relay, which turns on when a certain compression force of the electrodes is reached. Mechanized versions are activated by a pedal or by pressing a button on the handle.
• According to the method of cooling the electrode holder. When using high welding currents for contact welding, it is more efficient to use water; in other cases, cooling is carried out using an air jet.
• In terms of performance. Water-cooled welding tongs are capable of providing a welder's work rate of 500,700 points per hour, and air-cooled tongs - no more than 6070.

A type of welding pliers are spotters - devices that provide manual clamping of electrodes. They are used for resistance welding of small parts.

How to work with welding tongs?

The presence of welding pliers eliminates the main problem of resistance welding - the need to supply large current values ​​to the working area while simultaneously ensuring the mobility of the welder. Welding wire is not suitable in such situations, so only electrodes should be used.

Special requirements are placed on the housing: it must ensure safe power transmission, reliable fixation of both clamping units and ease of use.

Therefore, welding tongs for industrial use are usually equipped with a fastening unit, with which they are attached to the more rigid part to be welded.

Preparation for welding using welding pliers begins with the installation of electrodes in the clamping units. A terminal clamp, which is more reliable, is used more often.

The most important characteristic of the equipment is the reach - the distance from the axis of rotation of the movable clamp to the axis of the electrode. The amount of overhang determines the maximum distance from the edge of the welded product.

In most equipment designs, the offset is a variable value and varies within 125500 mm. This increases the functionality of the device.

The reach can be adjusted smoothly and in steps. In cheaper designs, the amount of overhang is changed by reinstalling the electrode holders into the required grooves or holes on the body.

In automatic welding guns, the reach is sometimes adjusted using a plunger that is pulled out using compressed air.

However, such devices have not gained popularity among welders: the pliers are becoming heavier, and for stable air supply a receiver is required, which makes the equipment more cumbersome.

Having decided on the amount of overhang, the pliers are installed in the required location and the current supply is turned on. The relay will supply current to the electrodes while providing the required compression force. Having placed the next welding point, turn off the power using a pedal or handle, after which the tool is moved to a new position.

How to choose the size of welding pliers?

Industrially produced designs are focused on a strictly defined voltage - 220 V or 380 V. The selection parameters also include:

• Approximate hourly resistance welding productivity.
• The maximum permissible weight of welding tongs (from 78 to 1215 kg; in the latter case, the design provides for fastening the equipment).
• Design of the electrode clamping unit (a terminal clamp is more reliable than a threaded clamp).
• Cooling method. For example, water-cooled clamps are equipped with an external cooling chamber, which increases the size of the device.
• Characteristics of the electrodes for which the tool is designed.
• Method of connection to the cable.

It is worth mentioning a number of offered options that do not increase the functionality of the mites. In particular, the sometimes proposed arc discharge time controller is rarely used by welders, but it increases the complexity of preparing the entire set of equipment for work. When choosing, you should pay attention to the total energy consumption: if it exceeds 400450 kW, then it is advisable to choose an equally energy-intensive option.

For large-scale production, it is better to choose welding pliers for resistance welding, which allow you to simultaneously weld several dozen points. This tool is available in two types - serial and parallel. Productivity also increases when using hanging type welding jaws.

It is known from practice that it is more advisable to use manual welding tongs for contact welding of sheets up to 11.2 mm thick, and with mechanized electrode clamping for thicker sheet products.

Source: https://proinstrumentinfo.ru/svarochnye-kleshhi-dlya-kontaktnoj-svarki-tecna-topex-ktr-8/

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

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

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

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

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

Hardware Features

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

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

Spot welding methods

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

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

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

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

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

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

Welding options

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

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

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

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

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

Welding methods

There are several methods for spot welding:

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

Provides welding of steel sheets up to twenty millimeters thick.

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

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

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

Design Features

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

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

Requirements for technology for performing this type of work:

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

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

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

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

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

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

Advantages:

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

We make the welding ourselves

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

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

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

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

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

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

Safety precautions

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

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

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

Photo instructions on how to make a spot welding machine

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Welding guns for resistance welding

Welding pliers for resistance welding are the most popular tool when performing welding work. There are a huge number of different connecting devices, but the welding pliers option is preferred by most welders, as they have many advantages. For example:

• there is no need to purchase professional welding equipment or additional specific devices;
• ease of welding work - the welder only needs to heat the metal with electric current;
• the strength of fixation of the welded products allows for high-quality connections.

Working principle of welding tongs

The transformer, which has a significant mass, stands in one place during welding work. The welder connects a small portable device to it, with which he directly carries out the necessary work.

To connect the individual parts of the welding equipment, a flexible multi-core cable is used, which is inserted into a rubber hose with water for cooling.

Resistance spot welding pliers are a gun that is connected with one contact to the transformer and the other to the metal being welded.

With the help of such a gun, a welding point can be placed on any part of the product. In this situation, welding pliers will not be needed.

Features of welding work using tongs

• Metal samples are compressed with pliers, and thanks to the electrodes built into them, they are connected.
• Electrodes made of copper alloys with the addition of other metals are used. They are characterized by increased thermal conductivity, heat resistance, low electrical resistance, and retain their original hardness even after heating and contact with the metal surface of the samples being joined.
• “Crab” resistance welding electrodes can be attached to the tool in several ways - with threaded connections, inserted into specialized grooves or soldered.

Requirements that must be observed when using welding guns

• Preliminary preparation of products.
• Calculation of the electric current sufficient to perform welding work.
• Accounting for the time during which the desired area of ​​the part is affected in order to instantly connect it with another element of the main structure.
• Calculation of the force that must be applied for high-quality adhesion of the joined samples.

DIY tool

To make homemade resistance welding pliers, you need to have patience and a little effort. The material for making such a tool will require a dart with a diameter of 3 cm, made of copper, and its length should be at least 2 meters.

• The copper dart needs to be bent to form a U-shape.
• Identical holes with a diameter of 1.8 cm are made at the ends, then they need to be unfolded and a cut is made. The result will be two clamps for the electrodes.
• Next, you need to connect 9 A transformers in parallel - 2 pieces, where the connection of the primary and secondary windings is made directly.
• To regulate the current supply, you can solder a switch using triacs, equipped with a standard standby multivibrator designed for testing the shutter speed.
• Water will be used to cool the homemade ticks.
• Removing electrodes using a foot pedal.

• Transformer for welding.
• Lever for turning electrodes.
• Handle equipped with a pusher.
• Hinges fixing the lever, handle.

Some designs of pliers for resistance spot welding additionally have springs between the pushers, but are not convenient enough during operation. Compressing the spring after each subsequent turn is more difficult.

Recommendations for selecting tools

When purchasing a tool, be sure to check the current limit. The higher it is, the greater the likelihood of adhesion of large parts.

Example: With 3800 A hand pliers you can join sheet metal with a thickness of 1 mm.

It is also worth paying attention to the length of the brackets. This determines how far the electrodes will fly out.

Source: https://electrod.biz/vidy/contact/svarochnyie-kleshhi-dlya-kontaktnoy-svarki.html

Welding pliers for resistance welding. cook quickly and easily! — Tool Master

Thanks to welding equipment, you can perform numerous jobs. The designs of units for joining metals are also varied. One of the small devices is a welding gun.

They come in several varieties. Thanks to such simple equipment, you can quickly create spot seams. In addition to store-bought versions, there are also home-made analogues.

How they work and what you need to consider to create them yourself is described below.

Design and principle of operation

Resistance welding pliers have a simple device:

• current source (transformer);
• a structural grip that allows you to bring current-carrying ends on both sides of the product;
• electrodes;
• cable;
• launch control mechanism.

To create a welded joint, you need a device with a lower V value and an increased A. Transformers with a reinforced secondary winding are often used. The voltage from it is transmitted to the contacts, which are the copper electrodes. The latter are located at the ends of the pliers or brackets, allowing a part of the product to be inserted between them.

When the sides are aligned, the electrodes are compressed by hand or a pressing device (pneumatics).

At the same moment, a current with a large ampere value is supplied, which leads to local heating of the area to a molten state and mixing of the molecular mass into a single whole.

After hardening, a general structural molecular lattice and a strong connection in the form of a point are formed. The operation of the device is similar to a spotter, but with a two-way approach to the product. The diameter of the point depends on the current strength, the holding time of the electrodes, and their width.

Equipment advantages

Welding pliers are popular in small workshops and large enterprises due to a number of positive features:

• convenience of applying spot sutures on similar structures;
• speed of manipulation;
• the cost-effectiveness of the method due to the lack of consumables;
• light weight of portable devices;
• Several welding points installed close to each other make it possible to replace a narrow continuous seam according to the strength of the connection.

Resistance welding pliers are actively used for creating equipment casings, making cages, containers and communication paths for ventilation, and for installing small frame products.

Types of equipment

Spot welding pliers are divided into two types: manual and suspended. Both have the same operating principle, but differ in application possibilities. Hand pliers look like large pliers with copper teeth on the ends.

Cables from the transformer are connected to the opposite ends of the moving sides.

The pliers can be applied to the product from different sides, depending on the length of the reach, and produce welded spot connections in all spatial positions.

The design is lightweight. The tongs themselves can weigh a kilogram or more, and together with the current source up to 12 kg. This allows them to be freely transported around the workshop and to neighboring workshops. To operate, you only need to connect to the power supply.

Hanging models are mounted on brackets or tables. The tongs themselves are carried beyond the edge of the surface so that nothing interferes with bringing products to them for welding.

Due to the absence of load on the welder’s hands, it is possible to make the structure heavier with an additional mechanism for squeezing the electrodes. Pneumatic pushers are often used.

When working with such equipment, the welder’s hands remain free and he can easily hold and rotate the product being welded.

Important nuances when creating with your own hands

To make homemade pliers for resistance welding, you need to know a number of key factors that allow you to correctly select the parameters and other features of the equipment. Here are the most important ones:

• Current strength. The ability to work with different thicknesses of metal directly depends on the power of the welding unit. The transformer is responsible for generating the required voltage. The maximum value of 3500 A will allow you to weld plates and metal rods up to 1 mm thick on each side. A current of more than 6000 A allows you to make strong point connections on materials whose total thickness is 4 mm.
• Electrodes fly out. This word refers to the distance between the ends of the copper rods and the common axis of the pliers. The size of the inserted parts and the installation location of the weld point depend on this value. The smaller the overhang, the closer to the edge of the product resistance welding will be performed.
• Electrode material. They are made from copper with various impurities. Among them: beryllium, cadmium, chromium and others. The density of the material and the frequency of sharpening the electrode depend on this.
• Weight of ticks. The long sides of the tongs, which make it possible to create a decent extension of the electrodes, are fraught with the weight of the structure. Therefore, it is worth thinking about future frequent work and creating spot welding pliers with your own hands with optimal weight and reach that can handle the upcoming work. Designs that are too heavy will overload your hands, and fixing them on a table will limit the range of use and maneuverability.

Other important parameters of welding tongs that are worth thinking about when making your own are: the ability to move the electrodes, power from 16 to 75 kW, short circuit current, type of compression drive, diameter of the electrode holder, cooling of the electrodes. Of course, for rare household use, some of these functions and values ​​are not required, but for professional use they will be very useful.

Manufacturing process

You can start your journey to creating homemade pliers by making the design of the pliers themselves. You can use any available materials. For example, from a strip of metal 2-3 mm thick and 20 mm wide, you can bend two stepped parts.

The same shape can be created from a thick metal rod. A hole for the axle is drilled in the center of the “step”. It is important to install a thick dielectric between the two parts so that the contact does not close in the wrong place.

At the ends of one edge, holes are drilled for bolting copper electrodes. It is important to install these elements opposite each other. To compensate for the thickness of the dielectric spacer, you may have to bend the plates inward. The cable is attached to the opposite edge. To do this, holes are drilled and terminals are fixed.

To increase the safety of the product and ease of use, you can put a rubber hose on top of the handles or wrap them with several layers of electrical tape. If the device is planned to be used permanently, then a powerful spring is installed between the handles, and an additional lever-handle is screwed onto the edge of the end with the electrode to apply pressure.

A transformer with a rewound secondary winding is suitable as a current source. The last one can be a welding cable laid in three turns on the core.

If you connect two transformers in parallel, you can double the power of the device. For manual pliers, it is enough to install a general power button on the body.

On a suspended model, it is practical to place such a trigger mechanism on the clamping handle.

Contact welding pliers are very easy to make and use. They are widely used and will be useful in the country house and in a private workshop.

Source: https://cs-important.ru/obzory/svarochnye-kleshhi-dlya-kontaktnoj-svarki-varim-bystro-i-prosto.html

Design and principle of operation of resistance welding pliers

Resistance welding is one of the varieties of electric welding. It is used to connect thin-walled workpieces with a short discharge of very high current. The device for this method of work is called welding tongs.

Device

They are arranged quite simply and consist of the following parts and assemblies:

• transformer operating current source;
• a grip that makes it possible to supply electrodes on both sides of the parts being welded;
• contact electrodes;
• wires;
• control system.

The transformer converts the mains voltage, lowering it. Its secondary winding consists of several turns of thick copper bar that can withstand thousands of amperes of current. Voltage from the secondary winding is supplied to massive electrodes with pointed ends. They are applied on both sides to the sheet blanks to be joined and pressed tightly against them manually or using a pneumatic drive.

At the operator’s command, the control system closes the circuit through a relay, and a short pulse is sent to the electrodes. Current begins to flow through the electrodes and both workpieces, quickly heating and melting the thin metal in the contact area. Under the action of the clamping force, the melted zones are combined into a single whole and crystallize. A point connection is formed on the workpieces.

The welding clamp is moved to the next welding point and the process is repeated. This is how the spot weld seam line is formed. The diameter of the melted spot is determined by the size of the electrode, the current strength and the pulse time.

Important selection options

When choosing a device, you need to take into account its main characteristics:

1. Operating current . It determines the thickness of the workpieces to be joined. At a maximum current of 3500A, the thickness of the connected parts is up to 1 mm. A current of 6000A will allow you to deal with workpieces up to 4 mm.
2. Electrode protrusion . Determines the dimensions of the workpiece from the seam side and the distance of the seam line from the edge.
3. Electrode material . Copper alloys with additives are used: Be, Cd, Cr and others. They help extend the life of the electrode, increasing its strength and reducing the need for frequent sharpening.
4. Device weight . Welding pliers for spot welding are designed for frequent use, so a unit that is too massive will lead to rapid fatigue of the worker and reduce his productivity.

It is also important to take into account the type of drive for pressing the electrodes, the possibility of cooling them, no-load current, the range of adjustment of the pulse duration and some other parameters.

Clamping force

To ensure high quality and uniformity of the seam, the clamping force must be constant from point to point . In manual devices, a system of levers is used for this; in more powerful tabletop or pendant ones, a pneumatic drive with adjustable clamping force is used. The control system of such devices has a single button to turn on the drive and supply a welding pulse with a delay necessary for working out the clamping force.

Nutrition

Powerful step-down transformers are used as a source of operating current . They convert AC mains voltage of 220 or 380 volts. The secondary winding is a thick copper busbar or a split copper disk. The open circuit voltage is 2-5 volts.

The operating current for different models ranges from 2 to 35 thousand amperes.

Despite the heavy weight of the welding source, it is placed in the same housing with the apparatus at a minimum distance from the electrodes. This is done in order to avoid energy losses when transmitting heavy current over a significant distance.

Hanging model

This type of equipment is used in large repair centers and industrial enterprises with mass production that perform a large number of similar operations..

The most advanced models are equipped with a balanced suspension with a gyroscope, which stabilizes the position of the device in space. The housing houses a powerful transformer current source and an automated control unit that controls the current strength, clamping force and pulse duration.

A productive pneumatic system ensures quick supply of electrodes to the workpiece, clamping with a given force and rapid removal. The pneumatic system is powered from a general workshop compressed air line or from a separate compressor.

The convenient handle allows you to accurately point the device at the welding site and, by pressing a button, give a command for an impulse.

Manufacturers

When choosing a spot welding pliers manufacturer, you need to consider their time in the market and overall reputation . Companies with a long history value their good name, use the most advanced scientific developments and technical solutions to produce their products, and use only high-quality materials.

Such a device will cost significantly more if you compare it with the products of little-known companies. To reduce the cost of products, the latter strive to simplify the design as much as possible at the expense of durability and even safety.

Quality control procedures for materials, components and finished products at these enterprises are also often neglected. As a result, an inexpensive product does not last long and requires repair or replacement. At this point, it turns out that the service network of this supplier in the country is not developed. If a large amount of work is planned, it is better to pay more and give preference to products from time-tested suppliers.

Among Russian manufacturers, the Kalibr company stands out, among foreign ones - ESAB, Huter, Tecna.

Homemade

Start making contact pliers with your own hands from the base of the structure. To do this, take strip steel with a thickness of 3-5 mm and a width of 20 mm or a round rod of 12-16 mm. Two halves of the pincers are bent out of it. There should be a hole in the middle for the axle. The axle must pass through a non-conductive bushing made of getinax or fluoroplastic. This will avoid electrical contact between the electrode holders.

Holes are drilled at the ends for installing copper electrodes. The ends of the plates are bent so that the electrodes converge, moving along one line. At the other ends, the cables are cut, crimped and soldered.

Pieces of rubber hose are placed on the handles. This will isolate the welder’s hands from live parts and increase the convenience of work.

If you plan to install the pliers for resistance welding stationary and bring workpieces to them, one handle is fixed to the work table, and a pipe extension is put on the other to increase the pressure.

The secondary winding is removed from a transformer of sufficient power and replaced with two or three turns of welding wire or copper wire of a suitable cross-section. The welding pulse can be controlled via a foot switch connected via a power relay.

Welding pliers, made independently, will expand the capabilities of the home workshop in the manufacture of structures from thin sheet metal. It will only be necessary to check the power of the power supply network. If the power is insufficient, the operation of the device will have to be postponed until the electrical wiring is strengthened.

Source: https://svarka.guru/oborudovanie/vidy-apparatov/kleshhi-dlya-kontaktnoy.html

Making your own resistance welding with drawings

The resistance welding machine is not only easy to operate, but also easy to manufacture. The main thing is that it is not necessary to have the skills of this work. Even a beginner can figure out how to make homemade contact welding with his own hands and using available devices. What is a contact connection?

Types of contact welding:

• point;
• embossed;
• butt and suture.

Design

A resistance spot welding machine made at home can be designed to solve simple problems that arise in everyday life. With its help, it is easy to apply a seam necessary for repairs or manufacturing of products. Resistance spot welding is obtained by heating individual elements with electric current and ensures a reliable connection, and the product being repaired will last for some time.

The device functions directly depending on the dimensions of the material, its thermal conductivity and the power of the equipment.

The operating parameters are as follows:

1. Low voltage from 1 to 10V.
2. The work takes a few seconds.
3. Current strength from 1000 Amperes.
4. Small melting area.
5. The pressure applied to the area of ​​the repaired sample must be strong.

Automatic contact welding, done in a domestic environment, takes into account quality requirements if all parameters are met. To simplify the task, it is recommended to choose alternating current. In this case, the duration of exposure will allow for high-quality seams, while the time period will be increased. Such devices have a relay that provides time control.

It is not difficult to make a resistance welding machine with your own hands. It is quite simple to make. For these purposes, you can use current converters from an old TV as an autotransformer. Resistance welding from a microwave, as well as welding from an inverter or from a LATR will also work well.

When choosing the most suitable transformer, the windings are wound again, based on the voltage and current parameters. Designation of spot resistance welding in accordance with the requirements of GOST 14098.

A control scheme for a technical device is being developed, or you can use an existing one posted on Internet pages, again based on the specified parameters. The resistance welding machine is manufactured in accordance with the types of intended work. In many cases, resistance welding pliers are used.

The connection must be made correctly to ensure direct contact, including the passage of current of one parameter. Particular attention is paid to the transformer for resistance welding and the electrodes for resistance welding mounted on the pliers.

On units with insufficient attention to this criterion, sparking occurs and the final result is not achieved. A good solution would also be to do seam contact welding with your own hands from an inverter or to make a unit with your own hands from a microwave oven, as well as a microwave oven.

A resistance welder can weld all types of materials in accordance with the types of certification. Job openings always require initial training. Arc welding makes connections for more massive structures.

Contact butt welding machines must be safe during operation, and you also need to know for what purpose the device will be used. Homemade contact welding is made at home. To do this, it is taken into account that the thickness of the metal should be no more than 1 mm, and the cross-section of the wire electrodes should not be more than 4 mm.

The welding machine operates at 220 V and 50 Hz, with the output voltage ranging from 4 to 7 V. The pulse current is up to 1.5 thousand A. The resistance welding control unit can be made after watching the video.

The electrical circuits in the drawing combine the following designs:

• switch operating in automatic mode;
• circuits for operating control;
• power unit;
• transformer for resistance welding;
• single-phase thyristor for connecting power to the network.

The winding circuit includes a primary one, which has six outputs for turning on and providing current regulation in the secondary. In this case, the first one connects to the network, and 5 regulate the process parameters.

The starter circuit in the MTT4 drawing includes:

1. Thyristor switch.
2. Through two contacts, the load is simultaneously redistributed to the other 2 contacts through a transformer.

The control circuit consists of:

• power supply from a transformer;
• relay for closing contacts when voltage is applied;
• diode bridge performing the function of a rectifier.

Accessories for resistance welding:

1. Current-impervious housing.
2. A transformer on which a wire is wound.
3. Ticks.
4. Electrodes.
5. Electrical circuits.
6. A number of safety devices: gas pressure gauges at the pressure inlet.

Automation of the process is carried out using all components. A resistance welder must have certain skills when making seam or spot joints. Job openings in this specialty can often be found on the Internet.

Contact welding, the main structural element of which is a transformer, is done by hand. You can remove transformer equipment from any device; the main thing is to take into account the calculation of the transformer so that the current strength is at least 2.5 A. The old winding should be removed and the rings should be installed on the magnetic core made of thin electrically conductive cardboard. This wire is wrapped in varnished cloth in more than 3 layers.

To make the primary winding, you should use wires insulated with fabric for better impregnation, with a diameter of 1.5 mm. For the secondary, it is better to use a stranded wire 20 mm in diameter in silicon insulation. Calculate the number of turns based on the power of the device. After winding the perchvica, a cotton ribbon is wound, then the secondary is placed on it. Everything is impregnated with varnish.

A manual machine resistance welder must know all the structural elements. Vacancies for this specialty are in demand. Arc welding also has a transformer in its design solution.

Making pliers

The welding machine for resistance welding is equipped with pliers. Manual pliers for contact joining can be:

• remote;
• stationary.

The second option provides good insulation and perfect contact with the electrodes. To do this, you need to make the remote lever long. It is easier to make handles of the appropriate length on an external structure. The insulation of the moving joint must be reliable; as a rule, washers and bushings made of textolite are used for this.

Resistance welding pliers are manufactured with a specified parameter for the electrode extension in the form of points, which is also important, since the distance from the edge to the place where the parts are joined depends on it. Electrodes are made of copper or beryllium bronze. Welding pliers can also be made from the working part of soldering irons. This is convenient when connecting polyethylene pipes.

A welder on resistance welding machines must be certified, but only if he works in production. Doing spot welding yourself is not a difficult task, just like arc welding. Anyone can do it at home.

Execution of work

Arc welding is not suitable for welding individual points.

Before performing work, it is necessary to sharpen the electrodes for resistance welding, every welder on resistance welding machines knows this.

Flash butt welding is performed as follows:

1. Parts are installed between the electrodes.
2. Under the action of the pressing force, a frictional force is created between the electrode and the surface.
3. The maximum gap is set before applying voltage. As current flows, contact resistance is created.
4. Voltage is applied and the electrode moves, gripping the joints, forming a seam.

The connection of aluminum structures is carried out using contact butt welding. Contact welding of aluminum can be seam and spot welding. A welder on resistance welding machines can have the same qualifications as when working on inverters. Electric arc is considered the most dangerous.

Quality control of seams is carried out according to state standards. The standard is GOST 14098, which quality control workers are guided by and based on laboratory testing.

About the equipment

General mechanical engineering time standards for resistance welding are necessary to complete production tasks within a given period of time. For production needs, equipment is purchased, for example, Tecna resistance welding, which forms joints in the form of points.

PF Contact Welding LLC produces, repairs and retrofits inverter units. The plan of enterprises aimed at producing products in mechanical engineering must be carried out with the availability of modern devices.

Multi-spot resistance welding machines, including their technology based on the principle of welding mesh and rods in a stationary state. Roller welding with these machines combines methods of performing work in both intermittent and continuous steps.

Do-it-yourself resistance spot welding is needed to repair products made of thin metal, polyethylene, including polyethylene pipes, carried out end-to-end.

Today there are 91 welding units for resistance spot welding on sale. Resistance spot welding machine MT 1928 LM by PF Contact Welding LLC, made on the basis of semiconductors and capacitors, the kit includes:

• resistance welding regulator RKS 502 or resistance welding regulator RKS 801;
• contact welding pliers foxweld ktr 8 3097;
• The pic16f628 controller is installed on the winding.

The machine makes single-point connections, and it is also possible to connect polyethylene pipes. MT resistance welding is sufficient for welding reinforcement.

Using this unit, contact butt welding of wire is performed.

DIY spot welding (spotter).

The Aks 2M machine is used for welding copper and non-ferrous alloys; spot welding of batteries is performed. Do-it-yourself welding for batteries is simple in technology.

The sunkko spot welding machine is used to assemble a battery of cells. Sunkko 709a does not overheat the metal plate during operations, which can happen when soldering products. It comes complete with a soldering iron, and nickel is used during operation. Seam work is performed for polyethylene pipes end-to-end on pipelines, and plastic products can also be joined.

A professional resistance welder receives a specialty at an educational institution. Jobs for electric and gas welders, including a welder on resistance welding machines or a resistance welder, are always open at enterprises.

Source: https://metmastanki.ru/kontaktnaya-svarka-svoimi-rukami-izgotovlenie-chertezhi

Do-it-yourself welding pliers for spot welding: how to assemble, characteristics, application

In order to connect metal elements, welding is most often used. There are a lot of approaches and methods for it, and each is used depending on the situation and has its own pros and cons.

But the main criteria for choosing a technology have always been the speed of work, the properties of the seam and, of course, the characteristics of the metal used.

One of the methods - spot welding (also called contact welding) - combines most of the advantages: fast soldering, high accuracy, as well as connection quality, simple execution.

This technology can be used in production workshops and for home repairs. It works best when joining thin sheets of metal, which is why it is often used in automobile factories.

Spot welding has one secret nuance. To form the welding point, the master uses contact welding pliers (clamp). They can not only press elements, but also heat them with current pulses.

This addition ensures the strength of the weld. We will tell you how you can make welding pliers for spot welding at home yourself, so as not to pay extra for factory ones in construction hypermarkets, thereby making welding cheaper.

general information

Spot welding clamps come in hand-held and overhead versions. You need to dwell on the types of this tool for a couple of minutes to understand the nuances of their manual assembly.

Manual welding guns have a simple design. Just like all other hand tools (pliers, pliers, forceps), their system is based on a lever that regulates the opening and closing of the pliers.

The main nuance of welding pliers is the ability to use a transformer system. A transformer is connected to one handle of the pliers, which transmits current to the tool in order to create the connection.

Through one of the handles, the transformer mechanism transmits the generated welding current to the electrode rods. This is the main work of the clamping mechanisms. You press metal parts with pliers with your hands, and current flows through them.

Electrical force and compressive force create the welding point (hence spot welding). The process is not mechanized, it is performed from start to finish by the hands of the welder, so only he decides how quickly the elements will be welded.

Suspended clamps for resistance welding are rarely used in everyday life. But they can often be found in factories and among professional craftsmen who use highly specialized equipment for point technology.

These pliers are built into the device itself, and their operating principle is different. Yes, they are designed to squeeze parts together, but not by hand. Therefore, the productivity of work with hanging pliers is higher than with manual ones.

There is no point in assembling such houses, since, most likely, you do not have the equipment with which to use them.

Therefore, further we will talk about assembling hand pliers for the spot welding method.

Manufacturing

You'll spend less time in stores by making your own spot welding pliers. At the same time, you spend much less, and the money saved can be “used” on high-quality materials for welding.

Making and using handheld resistance welding pliers is easy. But at the same time they are suitable for any type of metal. Both a person repairing his car in a garage and a field work specialist will find a place for them. Their cost pleases thrifty people.

The first stage of making a homemade instrument is creating the base. Materials that everyone has at hand are suitable for it. It can be any steel or alloy, the thickness of which is no more than five millimeters.

Make several strips of twenty mm wide from a sheet of material. Their length can be different, it depends on your wishes. Wide metal rods are also suitable for the base. Give the ends of the blanks the shape of tongs.

Place the pieces obliquely relative to each other and join them together. Make a hole in the center that will be the point for adjusting the opening and closing of the pliers. Place a dielectric spacer between the plates at the hole location.

You also need to drill a hole at the end of one rod/plate so that you can attach the copper wire to the bolts. The opposite workpiece is also drilled. The hole in it is needed to attach the device cable and fix the terminal.

Insulate the metal of the spot welding pliers with electrical tape along with a rubber pad (this could be a piece of hose) after connecting and drilling the desired components.

These materials will protect you when working with electricity, and will make them more comfortable to hold in your hands. This design will be enough to support the welding clamps, but to secure them you will need to add a spring between the handles.

The current is supplied to the terminal also taking into account the rules. Its best source will be a transformer mechanism with a secondary superimposed winding. You can wrap the cable around the core three times.

To increase the power of spot welding, combine a pair of transformers that generate current.

Schemes for creating hand pliers are not easy to find, so try to think through their design yourself. To help, you can take video lessons on creating non-hanging pliers or advice from familiar craftsmen.

Conclusion

We told you everything we knew about making manual resistance spot welding guns. To do this, you don’t have to look for special materials, since you can get by with what you already have.

Despite the simplicity of such a tool, it is no worse than expensive factory pliers from stores. In addition, homemade instruments do not require special storage and care conditions.

If you do not use them on an ongoing basis, they will even “work with you” for more than one year.

How did you assemble the spot welding pliers by hand? What scheme did you come up with? You can help with your tips for newbies in the comments below this article. Perhaps it is thanks to you that someone will decide to assemble their first instrument. We wish you good luck!

Source: https://prosvarku.info/prisposobleniya-i-detali/svarochnye-kleshchi-dlya-tochechnoj-svarki

Welding tongs and resistance welding technology - Welding

Due to its characteristics, resistance welding is widely used in a wide variety of modern industries.

The rapid development of mechanical engineering, astronautics, aircraft construction, and carriage building has led to the need to perform a large volume of welding work when installing metal structures.

In the process, the need arose to separate the welding module of the machine from the main transformer. This is how welding pliers were born.

Double-sided welding technology

Spot welding method invented by Russian engineer N.N. Benardos, is widely used for point and overlap joints of a wide variety of surfaces. The principle of operation of such welding is to heat the sheets being welded at the point of contact with the electrodes until the metal melts at a point and a cast core is formed.

The pressure applied to the electrodes helps compact the metal at the point, making it as strong as possible. The welding current is applied after pressure is applied. This type of welding is used to connect products made from stamped and rolled sections of thin metal, as well as to weld round rods to sheets, to each other, etc.

d.

To produce spot welding, a number of devices are used: welding pliers, staples, welding guns, etc.

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Design of welding pliers

The technical characteristics of welding tongs and the compliance of their design with the tasks performed directly affect the performance of the welding station. Therefore, when designing such equipment, special attention is paid to all elements.

Welding tongs are designed relatively simply and consist of several main components:

• bracket (body);
• lever arm;
• electrode holders;
• electrodes.

An extension cord and adapter can be located between the electrode holder and the electrode.

The design features of pliers are largely determined by the complexity of manipulations and affect the quality of welding, the duration of downtime when replacing parts and troubleshooting. Although they are designed relatively simply, a number of serious requirements are put forward for some design elements.

Thus, electrodes, as consumable components, must have simple shapes for their rapid production, be effectively cooled and have high strength when interacting with the material being welded. Moreover, they must be shaped in such a way as to ensure the connection of parts with a minimum flange width.

No less important elements of welding tongs are electrode holders, extension cords, adapters, cables, etc. - although they last longer than electrodes, they must also be simple, minimally heavy and at the same time have the required rigidity for a given effort.

The main elements of the pliers are, as a rule, unified, which makes it possible to avoid costs in the manufacture of original parts and to replace and repair them in the shortest possible time. This condition also allows for efficient use of equipment and timely modernization.

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Welding pliers - operating principle

When working with pliers, the welding transformer, whose weight is usually several tens (hundreds) kilograms, is in place.

A portable device connected to it via a cable is the main actuator. The connecting cable for these purposes must have a multi-core structure and have a certain flexibility.

Often it is cooled using a water jacket - a rubber hose through which cold water continuously flows.

The clamps of the pliers compress the product and, using electrodes inserted into them, spot welding is performed. The compression force is adjustable. The electrodes are attached to the clamps of the pliers using a threaded connection, or, less commonly, by soldering.

The electrode material is mainly copper and its alloys. They include: cobalt, chromium, cadmium, etc. Copper alloys have low resistance against the backdrop of high heat resistance and thermal conductivity.

 As the electrodes heat up and come into contact with the part being welded, they retain their hardness.

In some cases, spot welding pliers are made in the form of a gun. Such a device is connected with one contact to the output of the secondary winding of the welding transformer, and with the second to the surface to be welded. With a welding gun you can weld surfaces with any geometric parameters at any point.

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Large and small dimensions

Resistance welding pliers can have different designs and differ in size and shape.

The lightest models, designed for welding small parts, weigh only a few kilograms and can be easily held even with one hand.

Heavy pliers, with the help of which critical connections of a large area are mounted, weigh tens of kilograms and are controlled by hydraulic or electric drives.

Many welding guns come with additional features that increase their efficiency and functionality. These are a pneumatic drive, an automatic time relay, a compression force controller, etc.

Automatic and non-automatic pliers

Welding tongs are also divided into automatic and non-automatic. In non-automatic machines, the current is turned on and the electrodes are compressed mechanically - by pressing a button or pedal.

Automatic models are equipped with a motor, pneumatic or hydraulic mechanism for compressing the electrodes.

Switching the current on and off in such devices is ensured using special devices - mechanical, electromagnetic and ionic relay interrupters.

Modern automatic welding guns can weld up to 100 spots per minute. There are modifications capable of simultaneous welding of up to 50 points.

They are used, as a rule, in conveyor production in the manufacture of complex parts (for example, car bodies). Such machines are divided into models of sequential and simultaneous operation.

In the first case, the electrodes work sequentially, in the second - simultaneously. A significant disadvantage of such units is their high energy intensity (up to 450 - 500 kW).

Source: https://svarkaman.ru/svarka/svarochnye-kleshhi-i-tehnologiya-kontaktnoj-svarki.html

How to make spot (resistance) welding with remote pliers

Previously, we already looked at how to make spot welding from a microwave transformer. However, you can only work with such a device permanently. But what should you do if there is a need to use suspended spot welding in hard-to-reach places, for example, when performing body work (welding car sills).

And in order to be able to perform such operations, external pliers will help us. But there is one nuance here: the longer the wires from the transformer, the more the power of the spot welding machine drops. Therefore, it is initially necessary to manufacture a device that is much more powerful. Of course, one transformer from a microwave is not enough here. You will need two transformers from the microwave, or you can use any other large transformer.

Watch the video

• How to make spot welding
• Secondary winding
• Assembly

How to make spot welding

In this case, for the production of spot welding, a TBS3-0.63 transformer (analogous to OSM1-0.63), whose power is 630VA, was used.

The primary winding is designed for 380V, and the secondary for 220V with taps for 22V and 5V. But the best thing is that this tape magnetic circuit is very easy to disassemble by unscrewing only one tightening screw.

Since the primary transformer is designed for 380V, and the home network is designed for 220V, it is necessary to completely remove all windings. It is necessary to unwind carefully, since we will still need this wire to wind the primary winding. When removing a 220V winding, I recommend calculating how many turns it contains, so as not to resort to calculations using the formula:

W=(30(35)/ S)*UW - number of turns of the primary winding, S cross section of the core cm sq, 30-35 conditional coefficient

U - voltage

The winding was made in 2 wires (so that the winding would heat up less), which was obtained when removing the primary and secondary windings. We wind it turn to turn, separating the layers with a dielectric (lacquer cloth). In total there were 264 turns, which were laid in 8 layers. And there is still a 14mm gap left for winding the secondary winding.

Measuring the current at idle showed a consumption of 0.36A (permissible XX current up to 2 amperes).

Secondary winding

As for the secondary winding, if the clamps were stationary, then 4 turns of wire with a cross-section of 100 sq. mm would be enough. But in this case, since the pliers are remote, the length of the wire from the transformer to the electrodes was 1.7 m. And the longer the wires, the more the power of the device drops.

Unfortunately, I do not know whether the power drop is due to a decrease in secondary current due to thin wires (relative to length) or due to voltage drop during welding. Therefore, I decided to wind 6 turns of 50 sq. mm wire to compensate for the voltage drop during welding.

The pliers were made from a 1/2″ water pipe 50cm long, through which the wires were pulled and bolted directly into the electrodes. Holes were drilled in the electrodes to a depth of 50mm to ensure the largest area of ​​contact between the wire and the electrode. The junction of the pincers is carefully isolated from each other with textolite washers.

The work with the transformer is completed. Now you can start making the body. There was a sheet of 2mm thickness available. It is quite difficult to bend a box made of such thick metal on a sheet bending machine, so grooves were cut in places where the bends were made using a grinder. While the edges are not bent, it is advisable to immediately drill and cut all the necessary holes (fans, sealed leads, etc.).

If there are cuts, bending a thick metal box evenly is not difficult.

Ventilation holes must be provided in the lid. You can simply drill a lot of holes, but this is time-consuming and ugly. Therefore, metal ventilation grilles were purchased, and holes were cut in the lid for these grilles.

Assembly

After painting the body, we begin assembly. We install sealed leads (so that the wires do not rub against the edges of the case), and 12V computer fans.

Since the hole for the fans was cut rectangular, standard grilles for the cooler would not look nice. And for aesthetic reasons, a rectangular ventilation grill measuring 160x80mm was installed. Unfortunately, it was not possible to find a metal one of this size, so I had to settle for a plastic one.

Since there was a desire to assemble a compact spot welding machine, the distance from the transformer to the sides of the housing is only a couple of centimeters.

All electronics: a 12V power supply, a timer and a triac on the radiator were located on the side ties of the case. The radiator is positioned so that it is level with the ventilation hole of the cover.

To protect against overheating, two thermal fuses were installed. One thermal fuse is installed between the windings in the transformer. And the second is attached to the triac.

The front panel contains a device power button, a timer, and LEDs indicating the network is turned on and the transformer is operating. Since the current consumption of the device during welding is more than 20A, it should be noted that in this case the button only turns off the 12V power supply. And since the triac does not work without power, the device can be considered de-energized.

But this is not an entirely correct solution, since in the event of a breakdown of the triac (voltage surges, factory defects, etc.), the transformer will turn on, and if the clamps are closed, overheating and ignition will occur. Therefore, in order to prevent such an outcome, it is necessary to install a 25A circuit breaker as a switch, or after completing work, disconnect the device from the outlet, or do not leave the clamps closed.

As for the timer, it is not at all necessary to install it, since it is mostly necessary for welding thin wire. And sheet metal can be completely welded without a timer.

The transformer control circuit, without a timer, is quite simple and does not contain many elements.

For welding parts made of thick metal, a timer is, in principle, not needed. But if you have to work with thin metal or for welding wire, then a timer with power adjustment is simply necessary.

Since it is not so convenient to work with such large pliers, an additional handle was attached, which will allow you to work with pliers with only one hand (CRAB clamp). A control button was located on this handle, and a heat tube was placed on the handle itself.

After painting, we insert the wires into the pliers pipe and install them into the electrodes. At the ends of the pipes, pieces of 3/4″ pipe are installed to strengthen the threads, so that the threads are not stripped by tightly screwing the bolt.

It is worth noting that the rods are made of metal, so you do not need to use a release spring. And it is worth paying special attention to the isolation of the pincers so that the CRAB mechanism does not close the two halves of the pincers together.

This is what a spot welding machine looks like after painting. Since the device weighs 16 kg, it is necessary to install a carrying handle on the lid.

Due to the fact that long wires, thick metal cannot be welded, but with a package of 4 galvanized plates 0.5 mm thick or three ferrous metal plates 1 mm thick, it copes quite well. You can see how the device copes by watching the video after 10 minutes.

Source: https://sense-life.com/hand-made/tochechnaya_svarka_2/