Device and method for performing friction stir welding on thick plate without keyhole formation

Abstract

The invention provides a device for performing friction stir welding on a thick plate without keyhole formation. The device is characterized by comprising a withdrawn stirring needle system, a stirring needle withdrawing transmission system, electric brush systems and a resistance-type auxiliary heat system, wherein the withdrawn stirring needle system comprises a stirring needle fixing base, a withdrawn stirring needle and a fixing bottom plate; a plurality of chrome copper electrodes are uniformly arranged on the shaft shoulder surface at the lower end of the stirring needle fixing base as a shaft shoulder conductor; a conductive copper plate is embedded into the upper end surface of the fixing bottom plate; when the shaft shoulder conductor is in contact with a welded workpiece, the shaft shoulder conductor, the welded workpiece and the conductive copper plate form a conductive path; the stirring needle withdrawing transmission system comprises a stirring needle rotating base and a needle withdrawing main shaft; connection of the withdrawn stirring needle system and the stirring needle withdrawing transmission system is achieved through bolts; the electric brush systems are arranged on the end surfaces of the two side walls of the stirring needle fixing base; a switch is closed, and current is provided for the resistance-type auxiliary heat system through the electric brush systems. The invention further discloses a working method of the device. Through the device and the method, operation is simple, keyhole formation is avoided, and the friction stir welding efficiency and the product quality are improved.

Description

technical field [0001] The invention belongs to the field of welding, and relates to an electric Joule effect and a return-axis type stirring pin, in particular to a device and method for friction stir welding thick plates without keyholes. Background technique [0002] Friction Stir Welding (FSW for short) is a solid phase welding method invented by the British Welding Institute (TWI) in 1991. Due to the low welding temperature and the unmelted material to be welded, there is not only no welding defect in the friction stir weld, but also no spatter, no smoke, no radiation, no shielding gas, no filling wire, no slag removal, no deformation It is a new type of welding technology with low energy consumption and environmental protection. After more than 20 years of development, friction stir welding has been popularized and applied in more and more fields, and can successfully weld aluminum alloys, magnesium alloys, copper alloys, titanium alloys, lead alloys, stainless steel,...

AI Technical Summary

Problems solved by technology

However, in the process of friction stir welding thick plates, the frictional heat provided between the shoulder and the workpiece is mainly concentrated on the surface of the workpiece, and it is difficult to reach the root of the weld, so it is difficult to achieve sufficient plastic softening and flow at the root of the weld, and it is easy to produce root Defects, so it is difficult to weld thick plates such as aluminum and magnesium alloys, which limits the wide application of friction stir welding in thick plate connections

At present, the keyhole is usually eliminated by post-welding machining or plug welding, but the effect is not good enough. The retraction of the stirring pin is an efficient keyhole elimination technology.

In the prior art, the shaft shoulder is heated through the resistance wire and the heat conduction block device, and the heat is transferred to the workpiece to be welded, but the thermal efficiency is very low, and the equipment is cumbersome, it is not easy to operate, and the thickness of the weldable workpiece is limited.

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