Electro-plastic friction stir spot welding device and method thereof

Abstract

The invention provides an electro-plastic friction stir spot welding device, which comprises a stir sleeve, a stir needle in the stir sleeve, a clamping sleeve clamped outside the stir sleeve, and a welding cushion block, wherein two radial opening grooves are formed in the bottom of the clamping sleeve and the top of the welding cushion block respectively; electric brushes are mounted in the grooves; and the grooves are matched with the conductive blocks in the electric brushes in shape. The invention further provides an electro-plastic friction stir spot welding method, which comprises the steps of carrying out plastic softening on a metal material, communicating the two electric brushes with a direct current independently and respectively while compacting a welding workpiece by the clamping sleeve, enabling the polarities of the two electric brushes on the same horizontal plane to be opposite and the polarities of the two electric brushes on the same vertical plane to be the same, connecting a welding circuit, and finishing the welding operation by adopting a spot welding process. According to the invention, a high-density current is applied to the metal deformation direction by utilizing the electro-plastic effect of the metal material, so that the metal dislocation is promoted, the motion defect is overcome, the plastic flow capability of the metal material is improved, and the welding quality is improved.

Description

Technical field [0001] The invention relates to an electroplastic friction stir spot welding device and a method for performing spot stir welding using the device. Background technique [0002] Friction stir spot welding technology is a new type of solid phase connection technology, invented by the German GKSS Research Center in 1999. For details, see US Patent US6722556-B2. This technology uses a special stirring head composed of a stirring needle, a stirring sleeve and a clamping sleeve. By precisely controlling the relative movement of each part of the stirring head, the exit hole formed by the stirring head during the welding process is filled while the stirring head is retracted. Thereby forming a spot welded joint with a flat surface. [0003] Chinese patent CN102091860A discloses a double-acting ring friction spot welding method. This method changes the static clamping sleeve in the traditional friction stir spot welding into a rotating ring with a downward pressing action...

AI Technical Summary

Problems solved by technology

[0004] During the friction stir spot welding process, when the stirring sleeve is pressed in, a new interface will be formed on the side wall of the outer ring of the joint, and during the backfilling process of the stirring pin, this interface will form a new connection with the thermoplastic material extruded and flowing there. However, due to the relatively low interface temperature and insufficient plastic flow capacity of the material, the forming conditions of the new joint surface are harsh, which easily leads to weak joint surfaces, and even defects such as virtual connections and holes.

[0005] Patent CN102091860A changes the clamping sleeve into a rotating ring and presses it down. Although the forming conditions of the connecting surface are improved and the quality of the spot welding joint is improved, the realization of this method requires key technologies such as six-axis linkage, and the structure of the welding device is complicated. , and after the moving ring is pressed down, indentations will be left on the surface of the spot welding joint, which will affect the appearance quality of the solder joints

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