机械

针对7050铝合金车削成型和挤压成型的内螺纹开展损伤形貌分析和机械性能分析，基于自主研制的螺纹连接结构松动试验夹具和随机振动试验夹具，系统开展了在轴向激励下车削和挤压内螺纹/螺栓连接结构的松动行为研究。结果表明：内螺纹在挤压成型时材料发生塑性流动，螺纹表层组织呈流线分布，由于发生塑性变形时的冷作硬化，使得螺纹表面硬度高，质量好；挤压成型的内螺纹相较于车削成型的内螺纹更难以拉脱；挤压成型内螺纹的松动速率大于车削内螺纹；车削螺纹损伤程度比挤压螺纹严重，内螺纹的损伤主要集中在螺纹牙中部和牙底，螺纹表面损伤特征主要呈现为剥层、塑性变形以及犁沟。螺纹表面的磨损机制主要为疲劳磨损、磨粒磨损、粘着磨损。

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.