WHAT IS WELDING AND ITS TYPES

 

 

WHAT IS WELDING AND ITS TYPES

In industry and construction, as well as in repair, welding has become widespread. 

What is the essence of the process, what classification is accepted and what are the main characteristics of each class, you will learn from this article. Portable welding machine is a technological process that results in the formation of permanent joints of materials. Sometimes the concept is mistakenly attributed only to the technology of connecting metal elements. In fact, various types of welding allow you to securely fasten not only metal, but also glass, graphite, ceramics, plastic.

 The connection occurs under the influence of temperature at the inter atomic level, as a result of deformation, or when two methods are combined.
At the physical level, when welding, the atoms and molecules of the connected surfaces form strong bonds.
In order for such connections to occur, certain conditions must be met: the surfaces to be welded must be cleaned of dirt, oxides, foreign atoms; to facilitate the interaction of atoms with each other, their energy activation should occur; the work pieces to be welded must be placed at a distance that could be compared with the inter atomic distance in the elements. During the cooling process, a welding seam is formed at the joint. 

CLASSIFICATION OF WELDING TYPES

 The existing types of best welding welding machine can be divided into three classes.
These large groups are distinguished on the basis of such differences: the specifics of the technique; characteristics of the material to be welded; features of protection of the welding process from air exposure.
The method of influencing the details is the main criterion that allows us to distinguish the following three types of this process: Thermal welding.
It is performed with the help of heat, with the use of additional materials. A gas flame, a plasma stream, an electric arc can serve as a source of thermal energy for this type of welding.
Under the influence of high temperature, the filler metal melts, the resulting liquid fills the gaps between the elements. After cooling, an all-in-one connection is obtained. Mechanical welding. The main role in the connection of the elements is played by the external impact on the welded parts. All types of mechanical welding involve deformation of the surfaces, which leads to a tight bond at the molecular level. Under physical influence, the mechanical energy is converted into kinetic energy, which allows you to heat the elements to the desired temperature. Combined welding. Also known as thermo mechanical, it consists in a combination of the above methods. This process uses pressure and thermal energy. For example, the metal can be preheated to the desired temperature, and then an all-in-one connection is formed with the help of external influence. Each of the listed classes includes several types of welding process. The main criterion for separation is the source of energy that affects the surfaces to be welded. THERMAL WELDING CLASS The welding methods listed below are related to the formation of a welding bath during the process. Its formation occurs with the participation of two metals: the main and additive. A metal rod or electrode can act as a filler metal during thermal welding. The source of heat is a welding arc, a flame of combustible gas, a concentrated stream of rays, termite. The heat source used determines what kind of a particular method of connecting parts belongs to. 3.1 ARC Arc welding is the most common. It does not require special devices or tools. Arc welding requires a powerful stable discharge of electricity in an ionized atmosphere of gases. During the arc ignition, ionization of the arc gap occurs, which is maintained throughout the entire gorenje. dugout. Arc ignition is a process that occurs in three stages: The contact of the metal work piece and the electrode causes a short circuit. It serves to reach the temperature required for welding. Then the tool is removed for a short distance (from 3 to 6 mm). Such an action provokes the beginning of thermionic electron emission. The previous actions make it possible to achieve a stable arc discharge. This happens because the arc gap becomes electrically conductive. This type of welding is divided into three subgroups based on the method of connecting parts: manual-all actions with the electrode are performed by the welder manually, using electrodes with a special coating; semi-automatic-the wire acting as an electrode is automatically fed into the welding zone together with a protective inert or active gas and melts under the influence of current; automatic-the process is fully automated according to the specified algorithm, human control is not required. The material, the number of electrodes, as well as the method of their inclusion in the electric current circuit form another classification of the arc welding type into several subspecies: Welding with a non-melting electrode with a direct arc. A graphite or tungsten electrode is used, the additive material is not always used. Welding with a melting electrode with a direct arc. A metal electrode is used, at the same time the base metal is melted. Indirect arc welding. As a rule, this method involves the use of two non-melting electrodes. Three-phase arc welding. Arc Gorenje with this method occurs between the electrodes, as well as between the base metal and each electrode. 3.2 GAS In gas welding, the flame acts as a heat source. This makes this method suitable for use in the field and in places where there is no access to electricity, since power from the mains is not required. Another characteristic difference between gas welding and arc welding is that heating and cooling of the welded surfaces occur quite slowly and smoothly. Therefore, the technology is suitable for joining thin-walled steel, non-ferrous metals, as well as for surfacing. gazovaya.jpg This type involves the melting of metal under the influence of a flame, which is formed as a result of burning a mixture of combustible gases with oxygen.Gorenje Usually acetylene or propane is used, less often gasoline vapors or kerosene. The melting of the filler metal is involved in the formation of a seam at the junction of the elements connected by welding. 3.3 RADIATION The fields of application of the beam type of welding are radio components, electronic circuits and other micro-components. The process itself occurs under the influence of a light beam. Unlike other types of welding, this must take place in a special chamber with a vacuum medium. Otherwise, the beam will be scattered due to the density of the air. The ability to connect micro-parts is a distinctive advantage of this method, which cannot be achieved with any other. The technology is widely used in the radio-electronic industry. luchevaya.jpg Laser welding is distinguished by high-precision seams. At the same time, the heating of the surfaces is minimal, so even a thin material does not deform as a result of the connection. This method allows you to direct energy using a prism to hard-to-reach places that would not be possible to connect using other types of connections. The energy source can be not only a light beam, but also a stream of electrons from an electron gun. 3.4 THERMITE Thermite, which is used for this type of connection of parts, is a special mixture for melting metal. It consists of aluminum, magnesium, metal scale. The mixture in the form of a powder is poured into a heat-resistant container and ignited with an electric arc, propastron or a special cord. The heat that is released during the gorenje termite melts the edges of the parts. The molten part, mixing with the metal of the parts being welded, forms an integral joint — welding takes place. termitnaya.png The resulting compound is characterized by high strength. This explains the demand and popularity of this type of welding in working with large-sized products. In particular, the method is used for joining pipes, rails, as well as for surfacing large-sized products. 3.5 ELECTROSLAG None of the other types listed above is better suited for connecting thick metal parts with a thickness of 5 cm to 3 meters than electroslag. With such welding, vertically installed workpieces are closed on both sides with the help of movable sliders made of water-cooled copper. A layer of flux is poured on the pallet, which serves as a heat source, and an arc is lit under it. The molten flux becomes conductive, it melts the edges of the base metal and the filler wire well. svarka-pod-flyusom-10.jpg Welding of this type is used to work with all types of steel, cast iron, some non-ferrous metals. The industrial value of the electroslag method is very high, due to the economic benefits. The larger the surface area that can be welded, the more rational its use. 4. THERMOMECHANICAL WELDING CLASS Thermomechanical or combined types of welding joints are used when it is impossible to create a smooth seam in any other way. Most often, this way you need to connect small elements. There are three types of welding in this class: blacksmith shop; contact information; diffusive. Each of them involves a combination of thermal and mechanical effects on the connected parts. 4.1. BLACKSMITH SHOP The connection of iron blanks using a hammer and an anvil was known long before the emergence of modern types of welding. The quality of the joint directly depends on the skill of the blacksmith, as well as on how well the surfaces were cleaned of plaque before starting work. The master who performs welding in this way heats the blanks in the forge and connects them with hammer blows, placing them on top of each other. Only plastic metals will be combined in this way. Low productivity and insufficient reliability have led to a low demand for the forge type of welding. Sometimes a mechanized subspecies is used: when the heated workpieces are squeezed by a press. The described method is called press welding. 4.2 CONTACT INFORMATION The welded joint is formed in the process of plastic deformation. Contact welding is so named because heating occurs due to the fit of the needle surface to the product. At the contact points, the maximum amount of heat is released, which contributes to the achievement of a thermoplastic state or melting. Further compression provokes the formation of new contact points. This, in turn, contributes to the convergence of surfaces at interatomic distances, that is, welding. kontaktnaya.jpg There are various classifications of this process according to the type of welded joint, the type of welding machine, the type of current supplying the transformer. According to the type of welding joint, there are several types for solving different tasks: butt-the entire contact area is heated; point-connections are formed in places of compression under the influence of current; suture-involves the connection of overlapping parts with the help of roller electrodes; relief-protrusions are pre-applied on the plane, which are smoothed after the current is applied. Contact welding can easily connect small parts. It is high-performance, easily automated. For this reason, such welding is used in mechanical engineering as part of robotic complexes. 4.3 DIFFUSION The technology is based on diffusion, that is, the mutual penetration of atoms of the joined materials when tightly pressed against each other. Welding is carried out in a vacuum environment or an inert gas environment. At the beginning of the process, the parts are placed in a special chamber, where they are fixed and begin to transmit force. Under the influence of an electric current, the surface layers of the metal are heated to temperatures close to melting. This type of metal compound is facilitated by the high diffusion ability of atoms. A more reliable fastening of the parts can be provided if you leave them for a while under the influence of current. Welding of this type is used with poorly contrasting materials. The distribution of this method is not as wide as that of others in the group.