刀具摆角对复杂曲面轮廓精度的影响研究

目的通过优化五轴联动加工中刀具摆角参数,基于后置处理技术提高复杂零件表面加工的轮廓精度。方法针对回转轴非线性运动造成的刀具姿态误差过大会导致零件轮廓精度低,提出了一种摆角优化方法。首先,对回转轴线性插补产生的刀具姿态误差进行分析,控制回转角的摆动幅度大小和初始位置;其次,将线性插补后的刀轴矢量投射到理论上始末两点矢量构成的平面上获得新的插补矢量,通过线性插补刀轴矢量来优化刀具空间姿态;最后,以某叶轮试件通过仿真及实际加工实验进行了验证。结果通过摆角优化方法后,叶片轮廓与理论轮廓的轮廓误差由0.08 mm减小到0.04 mm,最大过切量也由0.03 mm减小到0.01 mm。刀具摆角优化后,能大大提高复杂曲面零件的轮廓精度。结论基于后置处理技术对五轴机床回转轴摆角进行优化,在通用算法基础上加载角度优化算法,开发专用的后置处理器处理G代码程序,是一种提高复杂曲面加工轮廓精度的可行措施。实验验证了该方法的有效性。

Influence of Tool Angle on Contour Precision of Complicated Surface

The work aims to improve contour precision of surface processing of complex parts based upon post processing technology by optimizing parameters of tool swing angle for five-axis linkage machining. A method of optimizing swing angle was proposed since excess tool posture error arising from non-linear motion of rotating shaft would lead to lower contour precision. First of all, tool posture error arsing from linear interpolation of rotating shaft was analyzed to control swing amplitude and initial position of angle of revolution. Then a new interpolation vector was obtained as tool-axis vector after linear interpolation was projected onto the plane theoretically consisting of vectors in initial and end point. Finally, it was verified by performing simulation and actual experiment using an impeller specimen. After the swing angle optimization method was applied, contour error of blade contour and theoretical contour was reduced from 0.08 mm to 0.04 mm, and the maximum overcut volume was also reduced from 0.03 mm to 0.01 mm. After the tool swing angle was optimized, the contour precision of the complex surface parts could be greatly improved. Swing angle of five-axis machine tool is optimized based on post processing technology. Loading angle optimization algorithm is developed based upon general algorithm. Developing a dedicated post processor to process G code program is a feasible measure of improving the contour precision of complicated curved surface. Effectiveness of the method is verified by experiments.