The successful design of (1) stirring head is the key to apply friction stir welding to a wider range of materials and welding thickness. This paper mainly discusses the development status of mixing head. Generally speaking, the stirring head consists of a stirring probe and a shaft shoulder, and the material of the stirring head is usually made of a material with hardness much higher than that of the welding material, so that the abrasion of the stirring head can be reduced as much as possible in the welding process. In the early stage, the reasonable design of the shape of the stirring head is the key to obtain a weld with good mechanical properties. The development of mixing head mainly focuses on two aspects: one is the mixing head with thread, and the other is the mixing head with three grooves. In essence, the two kinds of hybrid probes are designed to be conical, which greatly reduces the material rolling out of cylindrical hybrid probes with the same radius. Generally speaking, the mixing probe with three grooves is reduced by 70%, and the mixing probe with thread is reduced by 60%. If a mixing probe with a smaller diameter is used, the conical mixing probe is easier to enter the weldment and pass through the plastic material than the cylindrical mixing probe, which reduces the possibility of stress concentration and fracture of the mixing head.
(2) Research status: Friction stir welding is more and more widely used in aluminum alloy, and the research is more and more in-depth. It not only involves the welding of various homogeneous materials, but also studies the welding of various heterogeneous aluminum alloys. The welding thickness of aluminum alloy ranges from 1mm to 75 mm The corrosion properties, mechanical properties and microstructure of aluminum alloy platform gold welding joint were studied extensively. Friction stir welding is widely used in 6061a1/2024a1/ag, 2024A 1/Cu, 606 1AI/cu and even 606 1AI.
In 2002, based on the cooperation agreement on patent technology licensing, technology research and development and market development of friction stir welding signed by aviation industry corporation of china-Beijing Institute of Aeronautical Manufacturing Engineering and Welding Institute, Beijing Saifoster Technology Co., Ltd., the first professional friction stir welding technology licensing company in China, was established, which marked the official start of friction stir welding technology research and development and engineering application in China market.
Friction stir welding, as a new interdisciplinary method, can develop a variety of connection processing methods and technologies such as longitudinal seam welding, circumferential seam welding, keyhole-free welding, variable cross-section welding, self-supporting double-sided welding, three-dimensional curve welding, friction stir spot welding, backfill spot welding, friction stir welding surface modification treatment, friction stir welding superplastic material processing and so on.
After nearly ten years of rapid development, Saifost Company has successfully developed more than 60 sets of friction stir welding equipment, and applied friction stir welding technology in China's aviation, aerospace, ships, trains, automobiles, electronics, electric power and other industrial fields, creating considerable social and economic benefits, providing perfect technical solutions for aluminum, magnesium, copper, titanium, steel and other metal materials, and providing domestic and foreign users with different types and uses of friction stir welding industrial products processing. Including aviation cylindrical structure, aviation thin-walled structure, ship wide rib plate, high-speed train body structure, large-thickness radar panel, automobile hub, container profile wall plate, radiators and heat sinks of various structures, etc.