Analysis of all kinds of pneumatic valve sealing surface surfacing methods advantages and disadvantages

welding belongs to metal intracrystalline combined with the method of fusion welding process, has the characteristics of general welding method, but also has its particularity. Is to give full play to the advantages of the surfacing material performance advantages, save material and prolong the service life of parts. The physical nature of welding process and metallurgical process and the law of the thermal process is similar to the general welding process.
( Surfacing method
general welding method can be used for surfacing welding. According to realize the welding conditions, welding method is an acetylene flame welding rod arc welding, oxygen welding, submerged arc welding, gas protection welding and plasma arc surfacing, etc.
(1) electrode arc surfacing welding rod arc welding equipment is simple, easy to operate, suitable for field welding, strong adaptability, and is not restricted by surfacing welding position and shape of the workpiece, can undertake surfacing in any location, is especially suitable for small or irregularly shaped parts. With the development of welding materials and process improvements, welding rod arc welding application scope expands unceasingly. Such as application of electrode arc melting fluxed alloy powder, fusion depth can be obtained, surface smooth and excellent performance of surfacing welding layer. Welding rod arc welding defect is low productivity, high dilution rate, not easy to get thin and uniform of surfacing welding layer, poor production condition.
(2) - oxygen Overlaying oxygen - acetylene flame Acetylene flame welding temperature is low, can obtain the smaller dilution rate, welding layer surface is smooth, good quality is the wear-resisting occasion often use the process method of mechanical parts. Such as oxygen - Acetylene flame surfacing in ironmaking industry blast furnace charging bell to raise life times. Oxygen - Acetylene flame surfacing generally used in smooth surface with minimum modification processing capacity.
3. Submerged arc surfacing submerged arc welding is covered with a layer of flux in the welding area, make the arc ignition between artifacts and surfacing welding wire. Artifacts, surfacing welding wire and the solder melts at high temperature effect has been part of the welding arc, under the flux layer to form a closed cavity, arc burning within the cavity. Above the cavity covered with molten solder layer enclosure, separate welding molten pool from the atmosphere, forming good appearance of surfacing welding layer metal. Submerged arc welding with high efficiency, suitable for automation production, especially suitable for the large-scale container liner surfacing, etc. In addition to using welding wire, can also be used for submerged arc welding, in order to improve the welding deposition efficiency.
(4) gas protection welding gas protection welding can be completed in manual, automatic or semi-automatic mode. According to the use of electrodes, gas protection welding can be divided into melting polar gas protect welding and the melting polar gas protection welding. Melting polar gas protection welding heat generated by between electrode and workpiece as one of the electrode arc and molten solder wire produced; The melting polar gas protection welding arc is produced between the electrode and welding, arc heat will fill welding wire and base metal melting, forming welding molten pool. Depending on the type of shielding gas, can be divided into the CO gas protection welding gas protection welding, argon arc welding and hybrid gas protection welding, etc.
gas protection welding with protective gas protection, avoids the invasion of the air and impurities pollution, high welding quality, high deposition efficiency, small heat affected zone. Gas protection welding belongs to the bright arc welding, welding layer can be observed in the process of welding, and can achieve all position welding, especially suitable for welding of alloy steel and special alloys.
5. Plasma arc surfacing welding plasma arc surfacing welding using plasma arc heating method of a kind of fusion welding, plasma arc heat high concentration, temperature, arc column core temperature more than K. Plasma arc welding with welding layer, therefore, good performance, high bonding strength, good welding layer density, melting depth is controllable, low dilution rate of surfacing welding layer, forming rules and a series of advantages, and easy to realize mechanization and automation, manual operation is more convenient. Is a kind of very promising welding technology,
6 other electroslag surfacing welding method is using resistance heat melting welding material and welding method of the matrix metal molten pool formed. Electroslag surfacing can surfacing at a time big thickness, high deposition efficiency, can use solid welding wire, tube with a wire, plate, or of surfacing welding. Electroslag welding is suitable for welding large thickness, surface shape simple medium and large parts. But serious overheating surfacing welding process, welding workpiece must be after heat treatment.
vibration is arc welding with thin wire to make it a continuous vibration welding method, in the small electrical flow guarantee the stability of welding process. Heated parts, small heat affected zone, and can get thin and flat, high hardness of the surfacing alloy layer. Has been widely used in mechanical parts repair, especially widely used in automobile, tractor repair. Arc surfacing productivity is low, but the vibration welding layer abrasion resistance, fatigue resistance performance of repair parts, important parts for repair by certain restrictions.
high frequency induction welding by high frequency current heating melting welding material and form of surfacing welding layer method. High frequency welding, heating temperature slightly higher than the melting temperature of welding material, below the melting temperature of the substrate metal. So less heat can make the parts, small deformation, and can make the surfacing alloy with matrix metal to obtain a good metallurgical combination. High frequency induction welding is easy to operate, fusion depth, high productivity, for hardfacing layer thickness. ~ the mm, is widely used in mechanical parts wear occasions.
laser welding can realize accurate control of heat input, the thermal deformation is small, the chemical composition of hardfacing metal and dilution rate is easy to control, compact structure, good performance of surfacing welding layer can be obtained. Electron beam welding of high energy efficiency, can reach more than % and is not influenced by metal vapor heating of matrix, and the mechanical deposited metal cooling speed, the wear resistance of surfacing welding layer is good, but the laser overlaying welding equipment and electron beam welding equipment one-time investment is large, the high cost of operation, efficiency is slow.