Friction stir welding (FrictionStir Welding for short) is an invention patent proposed by the British Welding Institute (TWI) in October 1991. The friction stir welding process was mainly used to solve the welding of low melting point materials such as aluminum alloys. TWI conducted a lot of research on the characteristics and applications of friction stir welding processes, and applied for patents in 1993 and 1995, respectively. TWI mainly cooperates with large companies such as aerospace, marine, road transportation, aluminum plants, welding equipment manufacturers, etc. to develop this technology in the form of group sponsorship or cooperation and expand its application scope. The Edison Welding Institute (EWI) in the United States works closely with TWI and is also conducting research on the FSW process. Lockheed Martin Aerospace of Martian, Marshall Space Flight Center, Naval Institute, Dartmouth University, University of Texas, University of Arkansas, University of South Carolina, Stuttgart University in Germany, Adelaide in Australia Universities, Australian Welding Research Institute, etc. have conducted special research on friction stir welding from different angles.
Friction stir welding is the most compelling welding method since the advent of laser welding. Its appearance will make a significant change in the connection technology of non-ferrous metals such as aluminum alloys. Very good results have been achieved by friction stir welding of aluminum alloys. Currently, friction stir welding of zinc, copper, titanium, low carbon steel, composite materials, etc. is being carried out in Britain, the United States and other countries. Friction stir welding has a good application prospect in the aerospace industry.
Stirring head, the successful design of the stirring head is the key to applying friction stir welding to a wider range of materials and welding a wider thickness range. The development status of the mixing head is discussed below. Generally speaking, the stirring head includes two parts: the stirring probe and the shaft shoulder, and the material of the stirring head is usually made of a material that is much harder than the material being welded. This can reduce the wear of the stirring head to the welding process. The smallest. In the early stage, the reasonable design of the shape of the stirring head is the key to obtaining good mechanical properties of the weld. The development of mixing heads is mainly concentrated on two aspects: one is a stirring head with a thread, and one is a stirring head with three grooves. In essence, both types of stirring probes are designed as cones, which greatly reduces the amount of material rolled out of cylindrical stirring probes with the same radius. Generally speaking, the stirring probe with three grooves is reduced by 70%, while the threaded The stirring probe has been reduced by 60%. If a certain smaller diameter stirrer probe is used, the conical stirrer probe is easier to enter the weldment and pass through the plastic material than the cylindrical stirrer probe, and reduces the stress concentration and fracture possibility of the stirrer.
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