软固结磨粒群气压砂轮的力学特性分析

Mechanical Characteristic Analysis of Softness Consolidation Abrasives Pneumatic Wheel

提出以软固结磨粒群(Softness consolidation abrasives,SCA)气压砂轮为工具的加工方法,对磨粒群密集颗粒系统的力学特性进行分析,用于解决激光强化后局部高硬度区域难以高效光整的问题。引入软球接触模型建立磨粒软固结形态下的微观接触力模型,引入全局阻尼系数得出了磨粒蠕变时的位移和速度公式。通过PFC3D仿真,验证了接触力计算公式,建立了颗粒系统的接触力网。对单颗磨粒在z轴方向上的速度进行跟踪研究,证实了SCA在加工时的存在蠕变现象。结合修正的Preston的方程,针对激光强化自由表面进行加工试验。试验结果表明:在相同加工时间内,SCA累积高出游离磨粒近34.35%的材料去除量,且避免了刚性砂轮面向曲面加工时产生的划痕,SCA加工可大幅提升面向高硬度曲面的光整效率。

A pneumatic wheel tool based on softness-consolidation abrasives （SCA） is presented.Mechanical characteristic of SCA is analysed for improving the efficiency of fmishing proces when it faced with the laser hardening surface.The normal and shear microstress is established by the analysis of the soft ball model.According to the global damp coefficient,the formulas of displacement and velocity of SCA are given in the process of creep deformation of SCA,which is proved out by the PFC3D.The stress net of SCA is also simulated.The creep deformation of SCA is confirmed in accordance with the analysis of vz of the single particle.Combined with the modified Preston formula,the experiments about the material removal are carried out to the laser hardening freeform surface.The results show that the material removal rate of SCA is higher than the free abrasive＇s by 34.35%.And it also can avoid the deep scratches which are always produced by the grinding with the rigid wheel on the freeform surface.SCA is certified to improve the efficiency of the finishing process to the laser hardening freeform surface.