At the beginning of the 20th century, manual arc welding has entered the practical stage. In the 1920s, the United States made automatic arc welding machines. Submerged arc welding was invented in America in 1930.
In the 1940s and early 1950s, tungsten electrode, metal inert gas and carbon dioxide gas shielded arc welding appeared in the United States and the Soviet Union, which promoted the application and development of gas shielded arc welding.
195 1 year, the Soviet union invented electroslag welding, which became an efficient welding method for thick weldments.
In the mid-1950s, ultrasonic welding, friction welding and diffusion welding appeared in the United States and the Soviet Union. The appearance of plasma arc welding, electron beam welding and laser welding in the late 1950s and 1960s marked the development of high power density fusion welding, which enabled many materials and structures that were difficult to weld by other methods to be welded.
Nowadays, electric welding has been widely used in machinery, electronics, construction, shipbuilding, aerospace, aviation, energy and other industrial sectors. The weight of welded steel structures accounts for about 45% of the world's steel production. The proportion of aluminum and aluminum alloy welded structures is also increasing.
Looking forward to the future, on the one hand, new welding methods, welding equipment and welding materials will be further developed, and welding process performance and welding quality will be improved and improved; On the other hand, the mechanization and automation level of welding process will be further improved, and welding robots and welding manipulators will be further promoted.
Extended data:
First, the welding method
According to the different heating and pressure conditions during welding, welding methods are usually divided into fusion welding, pressure welding and brazing.
Fusion welding is a method of heating the metal at the weld of the weldment to a molten state during welding, and generally completing the welding without pressure. When welding, the heat source makes the metal at the weld of the weldment and the filler metal added when necessary melt rapidly to form a molten pool, which extends with the movement of the heat source and forms a weld after cooling.
According to different electric heating methods, fusion welding using electric energy can be divided into arc welding, electroslag welding, electron beam welding and laser welding. Fusion welding is widely used in various welding methods, especially arc welding.
Pressure welding is a welding method to connect the seams of weldments under pressure (with or without heating). In the process of pressure welding, generally no metal is added. According to the different welding mechanism, pressure welding can be divided into resistance welding, high frequency welding, diffusion welding, friction welding and ultrasonic welding.
Among them, resistance welding is the most widely used. Most pressure welding methods have no melting process, and there are no problems such as the burning of beneficial alloy elements and the immersion of harmful elements in the weld seam. However, the welding conditions of pressure welding are harsh and the scope of application is narrow.
Brazing is a welding method in which materials (solder) with lower melting point than weldments are melted, then the weldments are bonded, and then the seams of weldments are connected together after cooling.
Second, the welding principle
Electric welding is a kind of welding operation that uses covered electrode to melt metal parts at high temperature where arc connection is needed. Its working principle is: through the commonly used voltage of 220V or 380V, through the transformer in the electric welding machine, the voltage is reduced and the current is enhanced, and the electric energy generates huge arc heat to melt covered electrode and steel, while covered electrode melting makes the fusion between steels higher.
Arc welding is the most widely used welding method, including manual arc welding, submerged arc welding, tungsten gas shielded welding, plasma arc welding, metal gas shielded welding and so on. Because arc welding uses power supply, the high-temperature arc generated by it is easy to cause fire and explosion, which is more dangerous.
References:
Baidu encyclopedia-electric welding