Structural Optimization Study of Stationary Shoulder Friction Stir Welding Head with Non-Rigid Support

Abstract In order to improve the quality and efficiency of repairing the aluminum alloy wagon body of the railroad, a stir friction head structure suitable for welding repair of aluminum alloy wagon body is optimized when adopting stir friction welding technology. By analyzing the relationship between the stir welding friction head structure and the heat generation mechanism, an approximate stir friction head structure without moving shoulder is proposed. By analyzing the heat production model of the stir needle with stationary shaft shoulder, the functional relationship between the heat dissipation and the size of the stir needle and process parameters is determined, and the geometry of the stir needle is optimized. Simulation and experimental results show that when welding repair is performed using this optimized stir needle structure, the temperature field of the weld is uniformly distributed along the thickness direction of the weldment, which is conducive to the formation of good welded joints and welds. Practical application in the field shows that the optimized structure can solve the problems of insufficient top forging force and local stress concentration in the process of non-rigid support while ensuring heat production, greatly improving the success rate of welding, and the tensile strength of the weld seam and other indexes have reached a more satisfactory result; the optimization method used has a certain reference value, and it can be used as a reference for similar researches.