Self-holding stationary shaft shoulder friction stir welding device and welding method thereof

Abstract

The invention relates to a self-holding stationary shaft shoulder friction stir welding device and a welding method thereof. The device solves the technical problem that a box-type structure to be welded assembled by hollow profiles needs double-sided friction stir welding. The device is provided with a stirring needle, wherein an upper section of the stirring needle matches a clamping handle through an upper position key, the clamping handle is connected to an upper shaft shoulder through an upper thrust bearing, a middle section of the stirring needle is provided, through tapped, with a first fine thread to be connected to two limiting nuts, the two limiting nuts are connected to two middle shaft shoulders through two middle thrust bearings correspondingly, a lower section of the stirring needle sequentially matches a lower shaft shoulder and a lower thrust bearing, the bottom end of the lower thrust bearing makes contact with a flange nut, and the flange nut matches the stirring needle through a second fine thread of the lower section of the stirring needle. The device is simple and reliable in structure, convenient to mount and dismount, adjustable in shaft shoulder distance, capable of adapting to welding of different hollow profiles and good in manufacturability and universality, the stirring needle rotates and the shaft shoulders do not rotate in a welding process, welding heat input is remarkably reduced, and the mechanical property of a weld joint is improved.

Description

technical field [0001] The invention relates to the technical field of welding devices, in particular to a self-supporting static shoulder friction stir welding device and a welding method thereof. Background technique [0002] Friction stir welding is a new type of solid-phase welding technology, which can avoid defects such as pores, thermal cracks, and slag inclusions during the welding process, and can also avoid the burning of alloy elements. Therefore, it has a wide range of applications in the field of welding non-ferrous metals such as aluminum and magnesium. application prospects. During the friction stir welding process, the stirring head is rotated and inserted into the workpiece to be welded, and kept in contact with the workpiece to be welded with a certain pressure, resulting in a large downward force applied to the workpiece to be welded during the welding process. Therefore, during friction stir welding, it is necessary to place a support on the back of the ...

AI Technical Summary

Problems solved by technology

This design has the following problems: (1) Using two stirring pins, the installation of the welding head is complicated, and it is difficult to achieve a high coaxiality, which leads to severe load fluctuations during the welding process, and the stirring pins are easy to break

(2) The versatility of the welding head is poor, and it is necessary to replace the load-bearing upper and lower shoulders to realize the welding of hollow profiles with different inner cavity heights

(3) During the welding process, the upper shoulder, the load-bearing upper and lower shoulders and the lower shoulder rotate at the same time, which requires a large motor power and a large welding torque. The stirring needle is easy to break and has a short service life; and the welding heat input is high, resulting in weld metal Coarsening of grains, dissolution of precipitated phase, and reduction of mechanical properties of joints

(4) The stirring needle is screwed into the threaded hole of the shaft shoulder through the thread at the end to fix it. This fixing method causes the broken part of the stirring needle to be stuck in the threaded hole and cannot be taken out, causing the shaft shoulder to be scrapped and the use cost is high.

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