Research On Speed Optimization Algorithm For Cam Grinding

Cam and camshaft are important parts of modern engineering machinery industry, playing important roles in the automobile, textile and some other industries. With the constant improvement of the NC grinding technology in recent years, the request of the cam grinding precision and efficiency is becoming higher and higher. To improve precision of cam grinding, the essence is to reduce the contour error. As we know, in the process of cam grinding, speed optimization is generally the way to inhibit the big error. After speed optimization, in order to meet the requirements of high accuracy, contour error compensation method is adopted to inhibit the small error at the same time. So the main research direction of this thesis is the algorithm of speed optimization which are the foundation and primary problem of all the cam grinding related research, only on the basis of this, further error compensation research can be proceed.Firstly, according to the basic principle of cam grinding, the most commonly used two methods, velocity instantaneous center method and the inversion method are respectively selected to establish the general mathematical model of the cam grinding. And the transformation from the lift table data to the input values of the servo system is completed. Base on this, combining with the characteristics of cam grinding and synchronous hysteresis principle, the influence of grinding speed on grinding precision is comprehensively analyzed by calculating and building modeling of the tracking error and contour error. From which, a conclusion can be made: the higher grinding speed, the lower grinding accuracy, on the contrary, the lower speed and the higher grinding accuracy.Secondly, the algorithm of variable step size curvature subsection velocity is proposed. According to the analysis of the influence of grinding speed to grinding accuracy, grinding speed is allocated rationally with the breakthrough point of curvature. Alongside the grinding speed is substantially increased, contour error is also greatly reduced. Combining with the traditional constant angular velocity grinding, grinding accuracy and grinding speed are both greatly improved. A solid foundation for next research is laid.Thirdly, two speed optimization algorithms based on fuzzy control and an acceleration optimization algorithm are proposed. Contour error and curvature are partly set up as breakthrough point, and fuzzy control is applicated in both these two speed optimization algorithm. On the basis of the algorithm of variable step size curvature subsection velocity, grinding accuracy is further increased. The acceleration of two axes are constrained by the acceleration optimization algorithm, on the basis of these two speed optimization algorithm, which achieve remarkable results.Fourthly, a simulation platform with the simulink of MATLAB is set up, and a cam as the research object selected. The three kinds of speed optimization algorithm are respectively simulated and the validity of these three speed optimization algorithm and an acceleration optimization algorithm are proved. The improvement of the grinding speed, the acceleration constraint and the grinding precision are partly proved, and remarkable results are achieved. Finally, a comprehensive comparison of these three kinds of optimization algorithm and the traditional constant angular velocity grinding is made, and their respective advantages and disadvantages are analyzed.In this thesis, researches are made on the mathematical model of the grinding wheel feed axis and rotation axis, the contour error modeling, presentation of speed optimization algorithms and the related simulation. For the problems next step to solve, mainly concentrated in two uniaxial cross coupling control and online error compensation issues, in order to further improve the grinding accuracy.