精密转子表面为典型的复杂螺旋曲面,采用三坐标测量机较难实现高精度的测量。对此,基于螺旋曲面的数字化特征模型及其等距面的相关几何性质,将转子轮廓的测量转化为导程参数和端面型线的测量,并提出一套新型的转子导程、型线等主要几何参数坐标测量方案。阐述转子数学模型及其测量数据处理的若干基本方法,在此基础上模拟三坐标测量机的步进采样测量过程,实现测量结果的不确定度评价和测量采样策略的优化选取。针对导程测量中存在的螺旋线特征点捕捉问题,提出了型线匹配测量法;为解决测尖半径补偿问题,提出基于虚拟再测量的补偿评价方法和不补偿直接评价方法。通过仿真和实际测量试验进行验证,其结果与转子厂家提供的理论数据吻合度较高,表明此方案合理。
Surface of a precision rotor, the typical helical surface, is too complicated to measure accurately with coordinate measuring machine(CMM). Aiming at this problem, a new proposal, based on geometric features and digital models, expressing complicated helical surface and its offset surface separately, is carried out to simplify contour measurement into parameter lead and transverse section profile measurement. Mathematical model of rotor and some methods for processing measurement data are explained, on this basis, continuous sampling mode of CMM is simulated to evaluate the uncertainty and select the optimal sampling strategy of measurement. After that, a method for measuring lead by rotary profile match is proposed to solve the problem existing in capturing spiral feature points; two solutions, one solves the problem of probe compensation by simulation re-measurement and the other avoids it directly, are also proposed to evaluate profile error. Simulation and actual measurement are carried out accordingly, and the comparison between measurement results and theoretical data provided by manufacturer proves that this proposal is advisable.