基于Oxley-Welsh理论的7075铝合金干切削过程应变硬化效应研究

Research on Strain Hardening Effect in Dry Turning Process of Aviation Aluminum Alloy 7075 Based on Oxley-Welsh Theory

针对7075铝合金干切削过程中加工表面力学性能调控的难题和以往各切削模型将剪切区应力应变理想化假设造成的求解偏差,通过搭建切削试验平台,基于Oxley-Welsh理论重点研究了干车削过程中切削用量对7075-T651铝合金剪切区平均宽度及应力应变行为的影响规律,以及应变硬化行为对切削模型的作用,阐释了7075-T651铝合金干车削过程中工件材料剪切区的尺寸效应和应变硬化效应。研究结果表明,干车削过程中工件材料剪切区剪切角与摩擦角和前角之差呈负相关,由所建立的切削模型可知,根据刀具前角和摩擦角能确定对应切削工况下的剪切角。当7075-T651铝合金在切削用量为v=240m/min,f=0.05mm/r,a=0.15mm的条件下进行干车削加工时,加工工件均匀塑性变形最好,在服役过程中承载能力相对最强。

Aiming at the problem of adjusting and controlling the mechanical properties of machined surface in the dry cutting process of aviation aluminum alloy 7075 and the solution deviation of the previous cutting models caused by the idealization of stress and strain in shear zone,by the establishment of reasonable cutting test platform,based on the Oxley-Welsh theory,the effects of cutting parameters on the average width of shear zone and stress-strain behavior of aviation aluminum alloy 7075-T651 during its dry turning and the effect of strain hardening behavior on the cutting model are studied.And the size effect and strain hardening effect of shear zone of aluminum alloy 7075-T651 in dry turning process are reasonably explained.The results show that the shear angle in the shear zone of workpiece material is negatively correlated with the difference between friction angle and rake angle during dry turning of aluminum alloy 7075.The shear angle under corresponding cutting conditions can be determined according to the tool rake angle and friction angle by the established cutting model.The workpiece has the best uniform plastic deformation,when aluminum alloy 7075-T651 is machined under the dry cutting conditions of v=240 m/min,f=0.05 mm/r,a=0.15 mm,and has the relatively strongest carrying capacity in service.