Embedded stirring friction spot welding method

Abstract

The invention relates to an embedded stirring friction spot welding method which can be used for the overlapping spot welding of heterogeneous or homogeneous metal and is particularly suitable for theoverlapping between aluminum or magnesium and a harder heterogeneous metal material. The method comprises the following procedures: firstly, drilling on a harder second base material in advance and tapping in a hole or respectively drilling two coaxial holes with unequal diameters on both surfaces of the harder second base material; adopting a subplate with a glenoid die on light holes with equaldiameters; then assembling in an overlapping form and demanding that an aluminum plate is arranged above the harder second base material and the hole of the harder second base material, which has a small diameter, is arranged at the upper side; starting a pin-free type stirring head to rotate and leading the pin-free type stirring head to be in contact with the surface of an upper base material;limiting the press depth of the stirring head within 0.25-1 mm or so without penetrating through the welding interface; rubbing for several seconds and then rotatably extruding an upper plate into thehole of a harder lower plate to finish welding. Compared with the traditional stirring friction spot welding technology, the method prevents the abrasion of the hard second base material on a tool, prolongs the service life of the tool, has no keyhole on a joint and has smooth appearance.

Description

technical field [0001] The invention belongs to the field of welding and relates to a method for friction stir spot welding. Background technique [0002] In the transportation equipment manufacturing industry represented by automobiles and light rail cars, in order to save fuel and reduce emissions, aluminum with light density is gradually being introduced to replace steel. Therefore, reliable welding of aluminum / steel joints is an inevitable Workmanship issues. However, it is well known that aluminum / steel joints cannot be welded by conventional arc welding processes because arc welding processes cause brittle intermetallic compounds to embrittle the joints. Therefore, reliable welding of aluminum / steel joints is a key technical problem to be solved urgently. Over the years, brazing, friction welding, etc. have been the hot spots in the research of aluminum / steel joint welding because they can avoid the melting of the base metal. Compared with friction welding, brazing ...

AI Technical Summary

Problems solved by technology

[0015] The purpose of the present invention is to solve the traditional friction stir spot welding of dissimilar metals (such as Al / steel, Al / stainless steel, Al / Cu, Ti / steel, etc.) There are two technical problems: one is the severe wear problem of the tool: when one of the second base metal 2 is steel, the steel has severe wear on the "needle" part of the stirring tool, which seriously affects the service life of the stirring tool and normal welding The process is carried out smoothly; the second is the problem of poor flatness of the appearance of the joint: the remaining keyhole is deep and the flash is large after the "needle" is pulled out, and the flatness is poor

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