Research On Constant Speed And High Accuracy Real-time Interpolation Strategy For Cam Grinding

With the economical globalization, high velocity and high precision will becomes 21th century characteristics in manufacture. Cam is one of important component of cam mechanism. It's profile is very complex, and it's machining quality and efficiency directly influnces the mechanism's operating performances. Therefore, cam's machining accuracy still is one of difficulty. At present, it mainly uses mechanical profile modelling grinding cam in our nation. This method exists in some limitations, and can not be satisfy with the variational market requirement especially in precision and flexibility. Aiming at this status, the article puts forward high precision real time interpolation for constant velocity grinding cam after whole studying on the status and existed questions for NC grinding technology both here and abroad, and researhes on correlative key methods.(1) Based on the demands of numerical value fitting, the fitting method for the cam listing table was presented taking use of cubic spline of accumulating chord, and then the cam's curvilinear equations were founded. The fitting precision and computational stability of the method were analysed in the paper, and provided a reliable method for cam.(2) Making a track scheme for grinding wheel. Based on tangent grinding principles, cam'eqyidistant curves equations was found and taked them use for grinding wheel. Research on the cam curves equations, the grinding wheel radius was found, and then the gringding wheel track curves were created finally.(3) Studied on high precision real-time interpolation for constant velocity grinding cam. Taking use of differencial principles, the interpolation for grinding cam was implemented through lucubrated in gringding principle and development of interpolation methods.By use of the equations of velocity and machining precision, the length of interpolation was obtained. At the same time, the question of velocity of interpolation was analysed in this paper, and the smooth method was created.(4) Grinding control of grinding wheel. Based on cam's eqyidistant curves, geometric and kinematical model between cam and grinding wheel was accomplished in X-Y and X-C coordinates, and the questions of speed is irrelevant between grinding and interpolation and machining precision can not control between cam nodes was solved. (5) Based on the interpolation, machining emulator was empoldered, in which interpolation precision 1nm,interpolation period 1ms and speed 300mm/s was accomplished factual feed speed 0.9m/min, basically approaches 1m/min of FANUC18i system in the same precision. The research results this method was adopted to realize constant speed and high precision grinding.There are some examples for every methods in this paper, which proves these methods are feasible. Finally, through the machining emulator, the method studied in the paper not only realizes constant velocity grinding cam within permissive error, but also realizes interpolation for irregular curves, in which there is only addition in the calculation and the operation is so simple that it completely fulfils the requirements of next era CNC.