大型叶片五轴联加工的几何误差控制

误差控制和减少加工误差是大型叶片曲面类零件五轴联动数控加工中的重要任务之一。本文作者基于分析和建立加工曲面的型面几何偏差与加工刀位规划参数的关系 ,提出几何误差的控制方法。基于刀具与工件的五维包络运动分析 ,对五轴联动加工中影响较大的的非线性误差进行较为严格的计算 ,提出自适应步长方法以有效控制刀触点轨迹误差。对五轴联动加工中的残余高度误差进行较为严格的分析 ,并提出有效控制几何误差的方法和措施。文中的方法结合CAM软件进行刀位轨迹计算 ,已成功地用于大型轴流式和混流式水轮机叶片五轴联动数控加工中 ,在满足精度要求下 ,加工叶片的效率有明显的提高 ,表明提出的方法和措施能有效控制大型塑曲面加工的几何误差。

Geometrical Errors Analysis and Control in for 5-axis Machining of Large Sculptured Surfaces

One of the important tasks in 5 axis machining of large sculptured surfaces is to control and reduce the machined errors. This paper presents the methods to control geometrical errors based on the establishing of the link between geometrical errors and the parameters of tool path planning. The non linear errors, which are majority of geometrical error during 5 axis machining, are strictly analyzed and formulated. Consequently, an adaptive step length method is proposed to effectively control the cutter contact path error. Moreover, the measures to reduce the scallop error in machining of the large sculptured surfaces are discussed as well. With the combination of this research with CAM software, both the large Kaplan and Francis hydro turbine blades have been successfully machined. It shows that the machined errors can be effectively controlled and the machining efficiency can be improved in the machining of the large sculptured surfaces by the proposed methods.