软固结磨粒群加工方法及材料去除特性的分析

New Finishing Method of Softness Consolidation Abrasives and Material Removal Characteristic Analysis

为了解决高硬度模具自由曲面光整技术难点,提出一种软固结磨粒群加工新方法(Softness consolidation abrasives,SCA)。所谓软固结磨粒群,特指由高聚物黏结剂黏结于气压砂轮基体表面的磨粒群体,其宏观上不像游离磨粒那样可自由移动,而微观上每个磨粒均受到黏结剂在各个方向的弹性支撑。结合层间弹性力学体系分析,讨论双层弹性体中(橡胶基体层-磨粒层)的力穿越问题,得到表层单颗磨粒的切削力学模型。建立基于应力修正的Preston方程,解决柔性基体供力时存在的应力滞后问题。根据磨粒硬度特性进行系数修正,给出材料去除经验公式。对磨粒群的切削力和速度进行数值模拟,建立材料去除的定量预估模型。总结高效光整加工的配比条件,并通过针对激光强化模具表面的光整试验,验证修正后的Preston方程的准确性。

Oriented to the high hardness mould free-form surface, a new method based on the softness consolidation abrasives （SCA） is brought forward. The key words ＇softness consolidation abrasives＇ mean the abrasives group is bond to the rubber bonnet by the polymer binder. Compared with free abrasives used in other polishing methods, it can get more stable support from nearby polymer to form effective cutting. The flexibility is propitious to achieve large contact between tools and workpiece. Combined with the lays elastic theory, the passing force is analyzed, and a cutting model of single abrasive is established. Hardness of abrasive is brought into the modified Preston equation as an important factor. A cutting empirical formula is obtained for the stress lag in the softness situation. The estimable model of material removal is given by the numerical simulations of stress and velocity. The empirical results show the modified Preston equation is propitious to avoid errors for calculation.