数控磨削圆柱凸轮导槽时的误差分析

The Errors Analyses in NC Grinding for Cylindrical Cam's Groove

普通的圆柱凸轮导槽精加工是采用和圆柱凸轮导槽宽度一样的铣刀来加工,而圆柱凸轮导槽的数控磨削加工中由于砂轮磨损以及对其的修整造成砂轮直径不断减小,这样由于砂轮直径小于导槽宽度,从而应用普通的数控坐标转换公式来加工就会使得加工出来的导槽上宽下窄。该文分析得出修整后砂轮允许最小直径的预估公式,并且还得出圆柱凸轮槽数控磨削精加工时直动滚子移动式圆柱凸轮导槽宽度误差的计算公式。通过一个计算实例来说明采用这一预估公式相比于实际值是偏于保守的,但是很接近,所以利用预估公式来预估砂轮修整后允许最小直径是可行的。最后指出由于CBN砂轮相比于普通砂轮具有更好的耐磨性,所以选用CBN砂轮来进行圆柱凸轮导槽的加工更合适。

The cylindrical cam＇s groove is fmish machined using the milling cutter with diameter same as the width of groove usually. In NC grinding, the diameter of wheel is gradually minishing due to wheel worn and dressing for it, the wheel＇ s diameter is smaller than the groove＇ s width, so in machining according to the prev- alent coordinates transform formula, the groove top ＇ s width becomes rather large than bottom＇ s width. In this paper, the advance estimate formula for allowable minimal diameter of dressed wheel is proposed. By a calcu- lation instance, it is verified that the value of the estimate is more conservative than the actual value but the former is very close to the latter. So to predict the allowable minimal diameter of the dressed wheel in NC grinding for cylindrical cam＇ s groove, using the advance estimate formula is feasible. And because of the CBN wheel is more wearable than the ordinarily wheel, for NC grinding the groove, using CBN wheel is more suitable.