一种薄壁悬臂叶片数控加工非均匀余量刚度补偿方法

摘要

It is difficulty to produce high quality thin-walled cantilever blades in numerical control led (NC) machining due to cutting force induced workpiece deflections which result in surface errors on the machined blades. The methodology presented in this paper aims to compensate the rigidity of blades for induced surface errors in finish machining by modifying the machining allowances in the rough/semi-finish NC machining procedure. To ensure this, a nonuniform offset surface is introduced. First, the influence of cross-sectional thickness on the deflection of thin-walled plates under concentrated forces is discussed. Second, linear and sinusoidal functions are adopted to plan the uneven offset values for the nonuniform offset surface respectively along the radial and cross-sectional direction of the blades. Finally, based on the primary cross-sectional curves, the nonuniform offset surface is constructed by lofting. The experimental results show that the nonuniform offset surface can improve the rigidity of the test blades in finish machining, and the test blades machined this way can meet the design requirements.%在数控加工过程中,因受到切削力的影响,薄壁悬臂叶片容易出现弯曲、扭转变形等问题而导致被加工曲面误差较大.针对该问题,提出了一种非均匀余量刚度补偿方法,将非均匀余量偏置面作为粗加工/半精加工零件面以提高叶片精加工时的抗弯刚度.首先,分析了集中力载荷下截面厚度对薄壁工件变形的影响;然后,对叶片径向和截面线方向分别采用线性变化和正弦函数变化两种方法进行叶片曲面非均匀余量刚度补偿设计;最后,基于叶片原始截面线,采用放样法构造出叶片曲面的非均匀余量偏置面.试验结果表明,采用非均匀余量刚度补偿方法可以提高被加工叶片精加工时的刚度,加工出的叶片满足了设计误差要求.