Welding works in industry and construction

 

Welding works in industry and construction

The creation of an integral connection of metals, using an electric arc, is called welding. In this way, one or more parts are assembled.

Today, welding is used in industry, in construction. Welding operations can be carried out anywhere, in various climatic zones, under extreme weather conditions. From space, to welding underwater objects.

It is impossible to imagine modern production without welding - too much has been created using this technology. From a garage to a large aircraft factory, from a kettle to an airplane-one or another type of welding joints is used or has been used everywhere.

New technologies for creating seams are introduced every year. Technologies for connecting materials are becoming more and more progressive. Often, when creating a new one, you have to remember the well-forgotten old one.

A vivid example of this is today's news about the restoration of previously lost technology at the Kazan Aircraft Factory, ELU-24. This type of welding work allows you to weld monolithic plates of titanium-magnesium alloy, of variable thickness. A unique, very high-tech welding used for the construction of glider structures in the aircraft industry.

Portable welding machines are becoming more accessible to ordinary citizens. At the moment, they are common even among non-professionals. In many private houses, garages there is equipment created for carrying out welding, small works.

The wide demand has generated a large-scale offer - the range of welding equipment on the market is simply huge. From semi-professional to household.

The main types of welding

The main types of welding, the most common:

1.   manual

2.   automatic

3.   argon.

Of course, these are not all possible technologies, but they are one of the most widely used.

Each type of welding has its pros and cons. Its subtleties and nuances. Each type requires one or another equipment, consumables.

 Manual arc welding

The most used, common welding. Due to the long-term use of well-developed technologies, therefore it is universal. The welding process takes place using a standard electrode.

Its advantages-you can work in any position, it facilitates welding in places that are difficult to access. It is often used in construction. A wide selection of electrodes produced by the industry allows you to cook various grades of steel. Easy transportation of equipment.

Disadvantages - low performance. The quality of the seams depends entirely on the qualification of the welder performing the work, which is a little predictable factor.

Argon welding

Welding of a seam, with the help of argon-is called argon welding. The inert gas allows you to create welding joints using melting electrodes. This is a convenient welding when connecting alloy steels. It is also suitable for welding non-ferrous metals.

With the help of argon, well-formed welds are easily created, using the ability to control the depth of penetration of materials.

Argon welding is usually performed by automatic machines. Especially for connecting non-rotating pipe joints.

The main disadvantage of this type is the low performance of the manual mode. Automatic is not always possible, in particular for differently oriented short seams.

Semi-automatic welding

The type of creation of welding joints is massively widespread in the machine-building industry. Carbon dioxide is used during welding operations. It is not demanding on the level of qualification of a welder working on such equipment.

It is used to create compounds of low-carbon steels.

Welding works will remain in demand by the industry and builders for a long time. It is impossible to imagine tomorrow without such technologies.

Brief classification of the main types of welding

Content:

1. Thermal type of welding

2. Electric arc

3. Types of electric arc welding:

4. Gas-plasma

5. Electroslag

6. Plasma

7. Thermomechanical type of welding

Welding, as a technological process, was known in the VII century in the form of forging and injection molding. Its rapid evolution began with the discovery of the electric arc and the subsequent invention of coated electrodes. The main leap in development occurred at the end of the twentieth century in connection with the introduction of laser, plasma and ultrasound technologies into production. The extensive development of electronics has made it possible to make the welding process automated, high-precision and high-performance. In the course of development, three main types of welding were distinguished, depending on the type of energy used to perform the connection:

thermal,

thermostatically,

mechanical (represented by cold, explosive and ultrasonic welding).

Thermal type of welding

Welding of this type is carried out with the help of heat. The effect of high temperatures leads to melting of the butt surfaces of the connected parts and their bonding during subsequent crystallization. The heat source can be an electric arc, a gas flame or a plasma stream.

Electric arc

This welding has become the most popular. To heat the contacting surfaces and their subsequent melting, an electric arc is used - a discharge that occurs between the end of the electrode and the metal surface being connected when an electric current passes. The thermal energy of the current is released into the electric arc and causes its high temperature. The impact on the metal leads to its limited melting and the formation of a welding bath of liquid metal. Upon cooling, the liquid metal crystallizes and forms a compound with a composition and strength similar to the parts being joined.

 Types of electric arc welding:

Manual arc welding (MMA, manual metal arc) is performed using piece electrodes with a different special coating (coating). This process can take place using direct (DC) or alternating (AC) current. The different coating of the electrodes forms a gas cloud during its melting to protect the welding zone from air, ensures the ingress of chemical additives into the welding bath to change the properties of the metal in the seam area and the stability of the electric arc itself. Welding by this method is possible in all spatial planes, welding transformers, rectifiers and inverters are used.

This method, provided the correct selection of electrodes, allows you to weld all types of metals ("black", "non-ferrous", any degree of alloying), makes it possible to work in hard-to-reach places.

MMA welding can be a choice for both a professional worker and a beginner. It is widely used in the construction and installation of metal structures, in various areas of heavy industry. This can be the choice of a locksmith's workshop for the manufacture of metal doors, a machine-building plant or an ordinary summer resident who decided to make grilles for basement window openings with his own hands.

Argon welding with a non-melting electrode in an inert gas medium (TIG, tungsten inert gas). There are tungsten, carbon and graphite non-melting electrodes. An inert gas is argon, helium, nitrogen, or mixtures of these gases, depending on the metal being joined. In this process, the weld is formed only from the metal of the connected parts, or with the addition of an additive, which uses metal rods and strips. The presence of inert gases or their mixtures in the welding zone protects the weld metal from the harmful effects of air components and maintains the stability of the electric arc. Such welding can take place using alternating and direct current. Low productivity is combined with high quality of the resulting seam. The workflow is time-consuming and requires the operator to have developed professional skills.

TIG welding is used when it is necessary to obtain critical seams that can withstand high loads and have an acceptable aesthetic appearance.

This can be welding of gas and oil pipelines, high-pressure vessels, items for the food industry, microchips in the electrical industry.

It is indispensable when working with thin-walled metal structures and sheet metal (up to 6 mm), with stainless, alloy, carbon steel, copper, titanium, magnesium.

Semi-automatic welding with a continuous melting electrode in an inert (MIG, metal inert gas) or active (MAG, metal active gas) gas environment. The role of the electrode is performed by a wire melting under the action of current, which is automatically fed into the welding zone. The wire enters a special burner, and a protective inert or active gas is also delivered there. The composition of the gas protection depends on the type of material to be welded. Such welding is possible only with a constant electric current. Its high performance compensates for the inaccuracy of the seam and splashing that occurs when using active gases (carbon dioxide, oxygen mixtures) as protection. Automatic wire feeding into the weld pool area and the possibility of electronic adjustment of the working settings in the devices make it popular among both professionals and beginners in the welding business.

This method has become widely used in European and North American countries. It allows you to work with low-alloy and high-alloy steels, with many types of cast iron, aluminum, copper, nickel, manganese and their alloys, to combine different types of metals.

Submerged welding. When connecting parts, a flux powder of different chemical composition is used, which covers the weld pool and the area of the cooling weld with a protective layer. During the thermal destruction of powder particles, a protective gas is released to ensure the stability of the arc and high welding quality. By changing the types of flux, they achieve certain properties of the metal at the junction.

This method, most often, has an industrial application and is fully automated from the supply of flux to the movement of the welding machine itself. Manufacturing of ship hulls, aircraft fuselages, railway cars and locomotives, rotors and turbines, satellite modules and tower cranes. Any metals subjected to this type of welding can withstand the most severe operating conditions, huge pressure and temperature differences.

Gas-plasma

In this type of welding, the metal is melted under the influence of a flame formed as a result of the combustion of oxygen mixtures of flammable gases.Gorenje For this purpose, acetylene, butane, propane, kerosene, gasoline, and hydrogen are used. The most effective is the use of MAF (methyl acetylene fraction), since it has a high gorenje temperature (2927 C) in oxygen and good heat transfer. This compound is not as toxic as dicyan (4500 C) and not as explosive as acetylendinitrile (5000 C).

The use of a gas flame as a heat source makes this type of welding independent of the availability of power supply. Therefore, it is widely used in the field, but it is unsuitable for automated industrial operation, due to low productivity.

Also, one of its advantages is the gradual adjustable heating of the metal, which is convenient when working with sheet metal. The use of such welding requires a lot of welding experience from the operator.

Electroslag

The melting of the edges of the joint in this type of welding occurs due to the heating of the slag from the flux melted by an electric current, which is poured into the opening between the two parts. In this process, a filler rod or wire is used. The main material for welding is all types of steels and cast iron, less often non-ferrous metals.

This type of welding is of great industrial importance and is used for welding thick-walled (40-500 mm or more) large-sized parts: turbine and rotor shafts, steam boilers and supports. The larger the area of the surface to be welded, the higher the economic benefit from this welding method.

Plasma

To melt the edges and connect the metal parts, a plasma jet is used, which is formed in the plasmatron or between the electrode and the metal surface. Such welding is characterized by a thin, precise seam and a large penetration depth. Therefore, it is used for connecting thin-walled and small parts in the electrical industry, massive and oversized blanks and structures in heavy industry, in construction and installation. Any types of metals are exposed to the action of a high-temperature plasma jet.

In addition to the above listed, thermal types of compounds include:

laser welding (a laser beam is used),

electron beam welding (an electron beam gun is used in vacuum conditions),

welding with embedded heaters (for welding polyethylene pipes using heating elements),

contact butt welding by reflow (a heating element with a fluoroplastic coating acts as a heat source).

Thermomechanical type of welding

Contact welding is characterized by heating of the connected parts and mutual deformation under pressure. Spot welding is performed using spot welding machines or small-sized pliers. Two parts are fixed between the electrodes, an electric current is passed through them, which leads to local heating of the metal. After that, the electric current is turned off and the pressure of the electrodes on both parts is increased. The crystallization of the local molten metal leads to the production of a spot welded joint. There is one-sided (both electrodes on the same surface) and two-sided (the electrodes are located on two welded parts) spot welding. The disadvantage of such welding is the possibility of performing only an overlap connection. It is characterized by high performance and the possibility of its automation.

Spot welding is widely used in the automotive industry. All over the world, car assembly conveyors work with the use of this type of welding. Compact and mobile spot welding pliers are used in individual garages and small auto repair shops for straightening work. Large car service stations and service stations use this welding to perform a wide range of body repair work.

Also, this type includes various butt and relief welding.Other types of thermomechanical welding are not so widespread. These include diffuse (the connection of composite and inhomogeneous metals in a vacuum or in a protective gas environment), forging (the connection of heated metals occurs due to plastic deformation), welding with high-frequency currents (passing high-frequency currents through the connected parts) and friction (rotation of parts relative to each other).

Having determined the type of welding process you need, you can easily choose the right welding machine, taking into account its individual characteristics. The welding process allows you to save metal by 30% or more, it is easily automated, it is characterized by reliability and tightness of the seam, low cost of work and low time costs.