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对环形抛光法加工大小口径工件面形不一致的问题进行了研究。在0.69 m环形抛光机上发现,Ф100 mm工件面形微凹时,Ф48 mm工件为峰谷(PV)值0.336λ(λ=632.8 nm)的凸面形。利用Winkler假定和Preston方程对工件的面形进行了研究,发现倾覆力矩是引起面形不一致的主要原因。对于圆形工件的理论计算结果表明,当工件和抛光盘之间的摩擦系数与分离器对工件的作用力合力的高度的乘积大于工件直径0.125倍时,工件将会变凸。对工件进行了加压、润滑和降低工件支撑位置等实验,发现加压不能改善工件面形一致性;在抛光液中添加润滑剂后一致性有了一定的改善,Ф48 mm工件PV值降为0.128λ;而降低工件支持位置后,大小口径工件面形不一致性问题得到了解决,Ф48 mm工件PV值降为0.058λ,且变为微凹面。此结果表明抛光盘与工件的摩擦系数不能太大,且分离器对工件的支持位置应尽量靠进盘面。
The problem of the inconsistency of the ring shape of the workpiece with the large and small diameter was studied. In the 0.69 m ring polisher, the Ф48 mm workpiece was found to be convex with a peak-to-valley (PV) value of 0.336λ (λ = 632.8 nm) when the Ф100 mm workpiece was slightly concave. The Winkler assumption and Preston equation were used to study the surface shape of the workpiece. It was found that the overturning moment was the main reason for the inconsistency of the surface shape. Theoretical calculations for circular workpieces show that the workpiece will become convex when the product of the friction coefficient between the workpiece and the polishing pad and the height of the force of the separator acting on the workpiece is greater than 0.125 times the workpiece diameter. Experiments were made to pressurize, lubricate and reduce the position of workpiece support. The results show that the pressure can not improve the consistency of the workpiece. The consistency of the workpiece is improved after the lubricant is added. The PV value of Φ48 mm workpiece is reduced to 0.128λ. When the position of workpiece support is reduced, the problem of surface shape inconsistency is solved. The PV value of Ф48 mm workpiece is reduced to 0.058λ and becomes a slightly concave surface. This result shows that the friction coefficient between the polishing disc and the workpiece should not be too large, and the support position of the separator on the workpiece should be as close as possible to the disc surface.