微铣金属表面微沟槽结构的粗糙度及形貌分析

Analysis of roughness and morphology of metal surface grooves by micro milling

为了提高和改善微沟槽表面质量,设计了高速微铣削实验,研究了微沟槽底面表面粗糙度和侧壁残留毛刺的变化规律。从理论角度引入了已加工表面的形成机理,建立了微观表面粗糙度理论模型,提出了刀具跳动对侧壁形貌变化影响的规律。利用三轴联动精密微细铣削机床加工微细直沟槽,并选取主轴转速、轴向切深、进给速度、刀具跳动量和材料组织结构为研究因素。采用多因素正交实验和极差分析法,对表面粗糙度值进行数值分析。铝合金,钢和钛合金三类微沟槽底面对应的最佳表面粗糙度值变化范围分别为1.073~1.481μm,0.485~0.883μm,0.235~0.267μm;无刀具跳动钛合金微沟槽壁毛刺的最大高度为7.637μm,而当刀具存在0.3μm的径向综合跳动量时对应的微槽壁毛刺的最大高度为21.79μm。铣削参数对表面粗糙度值的影响按从大到小依次为进给速度、主轴转速、轴向切深,且随着进给速度和轴向切深的增大,表面粗糙度值增大;随着主轴转速的增大,表面粗糙度值先减小后增大;在相同加工条件下,若微圆弧刀刃无磨损,微刀具的跳动量对微直沟槽侧壁表面质量有较大影响。同时,不同金属材料特性也是影响微沟槽表面质量的潜在因素。

In order to improve the surface quality of micro machined parts,micro milling experiments were designed to study the variations of surface roughness and sidewall residual burrs of micro grooves.First,from a theoretical point of view,the model of processed surface formation and micro machined surface roughness theory were introduced for the purpose of proposing changes to the sidewall for tool run-out.Then,typical parts were selected to process the micro straight grooves by the developed 3-axis linkage micro milling machine tool;the spindle speed,axial cutting depth,feed speed,tool run-out,and material organization structure on surface roughness were studied in depth.Finally,the milling surface roughness of the grooves was researched by adopting multiple factor orthogonal tests and analysis of extreme difference.The best surface roughness values for the three kinds of micro grooved bottoms made of aluminum alloy,steel,and titanium alloy are determined as 1.073-1.481μm,0.485-0.883μm,and 0.235-0.267μm,respectively.Without tool run out,the maximum height of the micro groove wall burr is found as 7.637μm,and the maximum height of the micro-groove wall burr is found to be 21.79μm when the tool has a radial composite runout of 0.3μm.The experimental results show that the parameters are listed in the effective order given below:feed rate,spindle speed,and axial cutting depth.With the gradually increasing feed speed and axial cutting depth,the surface roughness Ra of the groove bottom gradually increased.However,increasing the spindle speed caused Ra to decrease and then increase.Under the same conditions,if the arc blades are without wear,the tool run-out on the micro straight groove sidewall surface quality has a greater impact.At the same time,different metal material properties are also potential factors affecting the surface quality of the micro channels.