Key Technologies Of The Control System Of Camshafts Grinding Process With High Speed

Camshafts are very important for automobile engines and advanced textile equipments. Their machining quality directly influences the performance of these devices. The conventional method to make the camshafts is to utilize modular and ordinary grinding wheel. The products made by this way have not enough contour precision, efficiency and flexibility.To improve contour precision, efficiency and flexibility for camshafts grinding, this thesis is emphasized on the research on the key technologies and optimization algorithm for the grinding process control system according to the special grinding method with CBN grinding wheel .During this research,the latest research achievements in this field are followed.This thesis puts stress on the following aspects:According to the complexity of the camshaft surfaces contour, the three cubed splines are used to fit them, then the point of tangency between the grinding wheel and the camshaft part is calculated, which is based on the grinding point searching arithmetic and the analytical arithmetic.With that,the interpolation arithmetic for the camshaft surfaces contour is proposed according to the restrictions of the machine tool's velocity and accelerated velocity.which ensures that the grinding process meets the machine tool dynamical characteristics.The mathematical model has been deeply studied for the motion in machining camshafts.The mathematical function between the surface linear velocity and the part rotational velocity is established, and the mathematical models of the transmission units and the servo units of the machine tool have also been studied.With the high speed rotation of camshaft workpiece,the response of the grinding wheel reciprocating motion unit is slow down due to inertia ,which is a difficult control problem .The controller of the grinding wheel reciprocating motion based on a look-ahead forward technique is designed to solve the problem,and in the grinding wheel motion unit, the adaptability against the system disturbance is enhanced.Based on the fact that the control precision for a single axis is improved, the cross-coupled biaxial error compensation model has been established.A model- referenced adaptive control is introduced to adjust feedrate on line, which process is that the online error information is estimated by terms of contour error in order that the interpolation controller calculates the biaxial commond value. Therefore, the grinding process precision is advanced highly.Above all, an open CNC system is developped aiming at the CBN grinding machine for camshafts, following that a series control parameters are made certain. The experiment shows that the control arithmetics and the key techniques in this thesis have capacity of grinding camshafts with high speed and high precision.