基于加权支持向量机的凸轮升程误差拟合方法

A cam lift error fitting method based on weighted support vector machine

针对凸轮磨削加工过程中存在局部升程误差严重超差的问题,提出了加权支持向量机的凸轮升程误差补偿方法。首先根据圆率的符号判断凸轮升程误差值是否连续,然后建立了不连续点与相邻点之间夹角与加权值的关系。通过加权支持向量机对凸轮升程误差值进行拟合。然后将原始凸轮升程值减去经拟合后的凸轮升程误差值,获得新的凸轮升程值。再根据圆率自动调整加权值的系数,使凸轮升程值光滑点数最大,即获得最优的凸轮升程值。对上述算法进行仿真和编程,经YTM8336-16数控凸轮轴磨床进行磨削验证。实验表明,凸轮升程误差由原来的±0.059 mm降至±0.011 mm,表面粗糙度由Ra0.32μm降至Ra0.25μm,获得良好的效果。

Aiming at the issue of serious local lift errors in the cam grinding process, we present a cam lift error compensation method based on the weighted support vector machine （WSVM）. The circle rate of symbols is used to judge whether the cam lift error values are continuous, and then the relation- ship of angle and weighted value between discrete points and adjacent points is established. The values of cam lift error are fitted by the WSVM. The new cam lift values are obtained by subtracting the fitted cam lift values from the original cam lift values. Then, the number of smooth points of the cam lift val- ues can be maximized by automatically adjusting the weight coefficients according to the circle rate, therefore, the optimal cam lift values can be obtained. The algorithm is simulated and carried on the CNC camshaft grinder YTM8336-16. The results show that the cam lift error is reduced from 0.059mm to 0. 011 mm, and the surface roughness is decreased from O. 32μm to O. 25μm, which demonstrates the good effect of the proposed method.