钛合金螺旋铣孔孔径偏差研究

Hole diameter deviation in helical milling of titanium alloy

螺旋铣孔是航空航天领域新出现的制孔技术,其切削过程中会产生径向切削力,从而引起刀具变形并造成孔径偏差。针对该问题开展了钛合金螺旋铣孔孔径偏差试验,分析了包括进给方向在内的不同加工参数对孔径偏差的影响规律;基于螺旋铣孔运动学原理对不同进给方向下的材料去除过程和径向切削力方向进行了研究,分析了不同进给方向下的孔径偏差变化规律及形成原因,并设计切削力试验进行了验证;通过分析不同加工参数下的未变形切屑形状及径向切削力变化情况,研究了各加工参数对孔径变化趋势的影响规律。研究结果表明,当进给方向为顺时针时,刀具受背离孔心的径向切削力的作用向孔径外侧发生挠曲变形,导致所加工孔径大于理论孔径;当进给方向为逆时针时则相反。进给速度和导程的增加将加剧孔径偏差,切削速度的增加则会减弱孔径偏差。

Helical milling is a newly developed hole-making technology in aircraft assembly.The radial cutting force generated in the process of helical milling causes deflection deformation of the tool,resulting in hole diameter deviation.To overcome this problem,the hole diameter deviation test of helical milling is performed on titanium alloy,and the effect of different processing parameters including feed direction on hole diameter deviation is analyzed.Based on the kinematic principle of helical milling,the material removal mechanism and the radial cutting force direction are studied,and variation rules and the formation reasons of hole diameter deviation are analyzed in different feed directions,which is further verified by the cutting force test of helical milling.In addition,the shape of undeformed chip and the change of radial cutting force were examined with different processing parameters,followed by the study of the parameter effect on the change trend of the hole diameter.Results show that the tool is affected by radial cutting force in directions away from the hole center,leading to deflection deformation away from the hole center,and further resulting in hole diameter being larger than the nominal hole diameter in a clockwise feed direction.The opposite is true when the feed direction is counterclockwise.The hole diameter deviation is aggravated with the increase of feed speed and pitch,while weakened with that of the cutting speed.