All connection parts and assemblies goods depending on their designs can be divided into two groups: Mobile and stationary. Fixed connection in terms of potential showdown is divided into split (parseable) and all-in-one (non-parseable).

Plug connections can be disassembled without damage to the conjugate and fasteners. These connections are made deaf, tight, hard or dense plantings, screwed joints (screws, bolts, spikes, etc.), štiftovymi connections, etc.

The one-piece compounds include, Disassembly where not available during operation and accompanied by damage of conjugate elements. These
connection receive welding methods, soldering, riveting, gluing, landing with preload. Welding is one of the advanced ways to obtain permanent connections, providing significant savings in metal, reduced product weight and complexity compared to soldering, riveting, etc..

Welding called technology, the process of obtaining permanent metal compounds; alloys and other materials, carried out on the basis of interatomic forces coupling welded materials. Welding is widely used in engineering, instrument making, shipbuilding, bridge construction, aviation, When you create pipelines in construction and other industries. Welding connect as homogeneous, and dissimilar metals and alloys, metals with nonmetals (ceramics, glass, graphite, etc.), as well as plastics.

Welding can produce cold and heat welded parts. Cold welding necessary condition for obtaining high quality weld is pressure, order material yield strength of welded parts. At welding heat, the pressure is not a prerequisite.

All welding methods can be classified in many featured: physical, on the type of energy used, the method of weld formation, degree of automation.

By type of energy, used for heating the material in the welding zone, all welding methods can be divided into six groups: 1) electric, 2) chemical, 3} mechanical, 4) radiation, 5) Electromechanical, 6) chemical-mechanical welding.

Depending on the degree of automation of manual and semi-automatic distinguish automatic welding. By way of education, weld all kinds of welding are divided into two groups: melting and pressure.

Fusion welding You can expose all of the metals and alloys, including such, who have low plasticity (iron, aluminum casting alloys, magnesium alloys, etc.). Weld (all-in-one connection) is formed by mutual dissolution of molten metal workpiece in welding zone without application of external forces.

Welding pressure divided into cold and hot. Cold welding is subjected to only very Ductile metals (aluminum, copper, lead and alloys on their basis); hot pressure welding-metals and alloys, possessing good plasticity at elevated temperatures. Education all-in-one connection in this case is based on the processes of diffusion and exchange of atoms in Crystal lattices welded metals.

Ability of a material to form a reliable and durable weld called weldability. Good weldability possess low-carbon and low-alloyed steels, technically pure aluminum. Lower weldability are cast iron, high chrome steel, aluminium alloys, brass, Refractory metals.

The greatest use among different methods of fusion welding arc welding has, in which to melt the edges of the workpiece used an electric arc. An electric arc has a powerful light and thermal radiation (the temperature in the welding area is 5000-6004° c). ARC Burns between two electrodes, one of which, as a rule, is the welded part, the other is a metal rod or graphite rod (coal).

When you use the neplavâŝegosâ electrode in an arc to fill stitch injected prisadočnuû wire.

Plavâŝiesâ electrodes Depending on the destination may be nagotovleny of aluminum, steel, titanium, copper and other metals and alloys. To ensure stable arcing, protection of the weld and enhancing its strength properties to the coating of the electrode rod (obmazku). Improving the quality of the weld is also achieved the establishment of protective atmosphere, that excludes interaction of molten metal when welding with Wednesday. Protection is ensured by the use of flux., molten slag, inert gases (Argon, helium), active gases (nitrogen, carbon dioxide).

Electric arc welding subdivided into manual and automatic. Automatic electrode of welding howl under the layer of flux core operations — feed the electrode in an arc and moves in the direction of arc welding is mechanized. Welding is carried out on the welding machine. At the same time in the welding zone served flux, that has not only protective, but and alloying properties. In addition, flux removes metal spattering and helps improve welding current, get a great depth of proplavleniâ material.

The advantages of Automatic Arc welding under the layer of flux are: high quality weld,- more smooth and high speed welding (automatic welding in 20 times more powerful hand); smaller layer of deposited metal; possibility of weld seams of large cross-section in one pass, and therefore, save electricity; welding electrode wire can be uncovered.

A kind of automatic submerged arc welding, electroslag welding is. The welding process begins (e) excitation arc under the layer of flux.. After the melting of the flux and education enough liquid slag arc process stops and starts electroslag.

Metal electrodes, descended into the liquid slag, melts and flows into the weld drops. Passing through the slag, metal is cleaned of contaminants, ie. refined. Thus, the resulting weld has high mechanical properties and does not differ almost on strength and plasticity, of base metal. The weld is formed between two copper slide. This method allows weld workpiece virtually unlimited thicknesses and used for the manufacture of large-sized structures, such as frame presses, details of rolling mills, etc. Electroslag welding ensures high weld quality, high performance process and is one of the progressive methods of welding.

To obtain dense and durable welds details, made of copper, stainless steels, aluminum alloys, possessing poor weldability, applied welding atomnovodorodnaâ.

This welding, as a rule, carry out the independent actions of the arc, burning between two tungsten electrodes. In the welding zone for special channels is served èlektroderžatelej hydrogen, providing a protective effect and cars from the burning heat of arc to svarivaemomu metal. Thanks to this arc independent action provides a high temperature (to 4000 °C). To avoid possible explosion in atomic hydrogen welding does not apply pure hydrogen, a mixture of nitric.

To fusion welding and gas welding, based on the use of the energy of a gas flame, get gas during combustion (acetylene, hydrogen, propane, natural gas, etc.). Oxygen, the most common gas welding, use acetylene, has a high calorific value and ensuring the greatest flame temperature (3150 °C). For mixing oxygen and acetylene in a specified ratio and gain sustainable gas flame gas burners used.

Various ratios of fuel gas and oxygen in the mix change and welding conditions. So, normal, or recovery, plamenej (the ratio
volumes of oxygen and acetylene 1,1:1,2) weld most
steels, oxidising flame (with excess oxygen) -brass.

When welding aluminium alloys applied protective fluxes. Gas welding is applied, as a rule, for butt joints of workpieces up to 5 mm. To fill the weld joint using prisadočnuû wire.

Special methods of fusion welding include: electron-beam, laser and plasma cutting. Electron beam welding is used for connections of refractory metals and alloys. It is conducted in a vacuum electron beam narrow, which is produced in the installation, called electronic gun.

The electron beam has a high penetrating power, is, manage heat source, that allows you to accurately and fairly widely regulate the temperature in the welding zone. Electron-beam welding can be welded as homogeneous, and dissimilar metals and alloys, as well as metals with nonmetals.

For welding details, made of dissimilar metals and alloys and significantly different in thickness or diameter, as well as the melting temperature apply laser welding. Heat source with laser welding provides a laser beam. The laser beam is a beam of high energy density and concentration. It can be focused to the spots with a diameter 1 MKM.

This concentration of energy on the surface of the material allows to reach temperatures of several thousand degrees. Deflect the light beam of the laser by using optical systems (lenses), You can perform welding in tight places details, receive welds in the form of microdots. Laser welding is widely used in the electronic industry.

A plasma welding is used to join Refractory metals and alloys, stainless steels and many non-metallic materials. Heat source to melt the edges of the workpiece serves plasma Jet, generated by special devices-plasmotrones.

For welding pressure applies electric resistance welding, gazopressovaâ welding, diffusion welding in vacuum, cold welding, etc. Electric resistance welding is subdivided into three types: Scatter, šovnuû and seam. The essence of welding is, What welding details bring to contact each other, then pass an electric current through them, heat which warms the place of contact until the plastic State. Then the welding details served pressure, forming the weld, then the current is shut off and pressure is removed.

Reliability and high weld quality, the high level of mechanization and automation of the process, high labour productivity, enable you to make extensive use of Flash butt welding in industry; This method will receive more 30% welded joints, He is second only to electric arc welding.

When gazopressovoj welding workpiece are connected end-to-end. This method is similar to the Flash butt welding butt welding, but different source of heat: zagotonki heat mnogoplamennymi gas burners. Gazopressovaâ welding of inferior quality and performance on Flash butt weld, However indispensable under field conditions, When there is no source of electric current. This method is widely used for pipeline welding, Rails, concrete reinforcement, pipes.

Diffuzionnuû welding apply for those materials, that other methods to cook difficult go cannot (steel with cast iron, Titanium, niobium, Wolfram, glass, graphite, ceramics), for high-temperature, refractory and reactive metals, as well as to obtain multilayer (bimetallic, three metal) product.

Welding is carried out in a vacuum chamber under slight pressure at elevated temperature. In this method, the metal is in the solid state, but the temperature is close to the melting temperature of welded metals. Weld is formed as a result of mutual diffusion of atoms in the surface layers of materials kontaktiruemyh.

Cold welding all-in-one connection is formed as a result of plastic deformation and the emergence of the interatomic relationships between root surfaces with compressions of welded parts. Ground pressure is selected depending on the chemical composition and thickness of welded blanks.

The welding process accompanied by a hardening of surfaces at the place of application of force. This method of weld lap joint sheet material thickness 0,2 -15 mm, as well as end-to-end thin wire and the contour is a hollow billet. The advantages of this type of welding is high performance, low consumption of energy, high weld quality, extensive automation features. However, cold welding can be applied only for plastic materials.