Effect of Extrusion and Turning Forming Method on the Loosening Behaviour of Threaded Joints
This paper analyzes the damage morphology and mechanical properties of the 7050 aluminum alloy turning and extrusion forming.Based on the self-developed thread connection structure loosening test clamp and random vibration test clamp,the system conducts the loose behavior of the turning and extrusion connection structure under axial excitation.The results show that the plastic flow of the material occurs in the internal thread during extrusion forming,and the surface layer of the thread has a streamlined distribution.The cold work hardening when plastic deformation occurs results in the high hardness and good quality of the thread surface.The extruded internal thread is more difficult to pull off than the turning internal thread.The loosening rate of the extrusion forming internal thread is greater than the turning internal thread.The damage degree of the turning thread is more serious than that of the extrusion thread.The damage of the internal thread is mainly concentrated in the middle part and bottom of the thread tooth,and the thread surface damage is mainly characterized by peeling,plastic deformation and furrow.The main wear mechanisms of thread surface are fatigue wear,adhesion wear and adhesive wear.
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