加工工艺对7075 铝合金紧固孔表面质量的影响

为确定最佳制孔工艺、获得理想表面特性,从表面完整性和疲劳寿命角度对7075铝合金飞机紧固孔表面质量进行了实验性和数值仿真研究.通过比较常规多步制孔和钻扩铰一步复合工艺(Winslow),发现钻扩铰多步慢进给工艺(DBM)和Winslow所产生的表面具有较小的Ra值,较少的加工缺陷、较大的残余压应力及较高的疲劳强度,而后者的Ra值低于前者60％,疲劳寿命高于前者23％；基于实验数据,建立了切削参数对表面粗糙度和残余应力影响的经验公式；应用数值仿真分析了加工过程中应变和切削温度的变化规律；探讨了Winslow工艺的强化机理；指出适当减少进给量、增加切削速度能够提高紧固孔的表面质量.

Effect of Machining Processes on Surface Quality of7075Al Alloy Fastener Holes

To achieve the required surface characteristics,the experiment and simulation researches on effects of drilling processes on surface quality of aircraft fastener holes drilled on 7075-T7351Al alloy were conducted from the perspective of surface integrity and fatigue life.Compared conventional multi-step drilling processes with Winslow,it is found that there are smaller roughness vales (Ra),less operation defects,larger compression residual as well as higher fatigue strength on the machined surfaces produced by multiple-step with slow feed (DBM) and Winslow,and Ra of Winslow is lower than 60％,fatigue limit is 23％ higher than that of DBM.Based on test data,two empirical formulas affecting roughness and residual stress are established,and strain distribution and temperature variation are analyzed by numerical simulation.In addition Winslow strengthening mechanism are discussed.It is put forward that appropriate increase in cutting speed or decrease in feed rate can improve surface quality of fastener hole.