基于活动标架理论的加工目标曲面再设计及刀位计算

Target Surface Redesign and Cutter Location Calculation Based on Moving Frame Theory

为解决大型低刚度复杂曲面零件精度难以保证的加工难题,针对精加工目标曲面几何面形未知、随机形变误差远大于设计公差的实际加工特征,研究基于E.Carten活动标架理论的加工目标曲面再设计正向建模技术,以及以参考廓形及几何参数实测数据为依据的刀位点计算方法。在分析了可测参考面、加工基准面及加工目标面空间位姿关系的基础上,根据物理或几何约束要求,采用数字化手段再设计出精加工目标曲面,并利用曲面模型重新计算曲面加工刀位点。通过某型号液体火箭发动机变壁厚喷管冷却通道的加工试验验证,表明所提出的再设计数字化加工方法满足这类高物理性能和高几何精度曲面零件的加工精度要求。

The machining accuracy of large complex surface workpiece with low rigidity is very difficult to achieve.A typical characteristic should be considered in surface machining.The finishing surface model is unknown,and the random structural deformation is much larger than the design tolerance of target surface.A forward modeling technique for target surface redesign is developed based on E.Carten moving frame theory.And a computing method for cutter location points is then researched utilizing the measured data of reference profile and geometrical parameters.The spatial positions and orientations of measurable reference surface,datum surface and target surface are initially analyzed.On the base of the analysis,the finishing target surface is redesigned by using digital techniques in accordance with physical or geometric constrains.The cutter location points can be recalculated using the redesigned surface.An experiment of a liquid rocket nozzle with varying thickness was implemented.It is shown that the proposed method can satisfy the machining requirements of those workpieces with high performance and high geometrical accuracy.