基于修正Preston方程的气压砂轮加工特性

为了解决高硬度、高耐磨激光强化自由曲面难以高效光整的问题,提出软固结磨粒气压砂轮加工方法. 通过高聚物黏结剂在充气柔性砂轮表面构成磨粒层,使每颗磨粒受力后可以局部微动,影响周边磨粒群的受力状况而发生群体效应,达到软性条件下的应力集中,形成高效切削. 以拉宾诺维奇(Rabinoweizc)磨损理论为依据,引入硬度比例系数和表面硬度系数,结合磨粒粒度对材料去除的影响,给出修正系数. 结合弹性力学理论,对柔性基体供力环境下的材料去除进行应力修正,给出修正的Preston方程,提出该方法材料去除的量化模型. 建立砂轮表面磨粒群在任一接触状态下的速度计算公式,通过ANSYS仿真给出下压量与压力的关系谱图. 修正系数经实验验证基本与理论分析相符,证明该方法可以降低材料去除的量化误差. 根据不同磨粒粒度的实验对比,给出针对高硬度表面光整的工艺参照.

Processing characteristics of pneumatic wheel based on modified Preston equation

A new precision finishing method based on soft-consolidation abrasives pneumatic wheel was proposed in order to solve the problems of finishing method to mould’s freeform surface with high hardness and high resistance. Polymer binder was used to form a layer of abrasives on the surface of pneumatic wheel. Then every abrasive had micro-movement under the pressure and it would affect the adjacent abrasives to form group effect to achieve high-efficient cutting by concentration of stress. According to the Rabinoweizc’s theory, the correction coefficient was given for Preston equation with the introduction of hardness proportion coefficient, surface hardness coefficient and particle size. Combined with the theory of elasticity, stress coefficient was modified under the situation of soft-consolidation. Quantitative model of the material removal was presented by the modified Preston equation. The velocity equation was constructed for any condition of contact. Simulation was found for studying on the relationship between feeding distances and presure by ANSYS. The empirical results show that the correction coefficient accords with the theoretical analysis and it brings in great reduction of the removel quantization error. With the contrast of experiments with different abrasive size, processing parameters were given for further study.