软性磨粒流加工能有效解决复杂结构曲面的抛光问题。基于该技术特点，针对硬脆性材料加工存在的技术问题，提出一种面约束软性磨粒流加工方法，即通过在工件表面设置窄缝约束流道，利用多向磨粒流注入法，在流道中形成高速涡旋磨粒流抛光工件。同时，针对传统磨粒流建模无法描述磨粒-壁面碰撞行为的不足，提出一种基于计算流体力学与离散元法耦合的磨粒流建模方法（Computational fluid dynamics-discrete element method，CFD-DEM），并通过该方法得到了磨粒-壁面碰撞分布及工件表面材料去除分布，在此基础上研究了面约束软性磨粒流加工的均匀性。结果表明：入口直径是影响磨粒-壁面碰撞均匀性的关键因素，随着直径的增大，碰撞分布存在最优值；当磨粒流处于不同的流态时，流体黏度对材料去除的作用原理不同，低黏度流体下材料去除均匀性有明显提升。最后搭建试验平台，通过对比试验验证了建模方法及抛光方法的有效性，试验结果显示，面约束软性磨粒流抛光方法能够使得单晶硅表面粗糙度从506.71 nm降低到10.17 nm。
计时鸣
,
葛江勤
,
高涛
,
谭大鹏
,
陈国达
,
李琛
. 基于CFD-DEM耦合的面约束软性磨粒流加工特性研究[J]. 机械工程学报, 2018
, 54(5)
: 129
-141
.
DOI: 10.3901/JME.2018.05.129
Softness abrasive flow processing method can effectively resolve the processing problem of workpiece with large plane or irregular geometric surface. Based on this advantage, to overcome the processing problem of hard brittle materials of existing methods, a surface-constrained softness abrasive flow processing method is proposed. Through setting the narrow constrained flow passage on the surface of workpiece, and adopting the multi-directional injection method, the high speed vortex abrasive flow can create and polish the workpiece. Traditional modelling method of abrasive flow is hard to reflect the particle-wall contact effect which is with important significant in fluid-based processing field. To address this problem, a computational fluid dynamics coupled with discrete element method (CFD-DEM) modelling approach oriented to abrasive flow is proposed, and the particle-wall collision distributions and the material removal distributions can be obtained. On this basis, the processing uniformity of the proposed processing method is studied. The results show that the inlet-diameter greatly affected the uniformity of particle-wall collision distribution, and the collision distribution can obtain an optimal value with the increase of inlet-diameter; with the change of particles flow pattern, the mechanism of fluid viscosity on the material removal will be different, and the uniformity of material removal can increase by the processing of low viscosity abrasive flow. Finally, a processing apparatus is developed, and the comparative experiments have validated the effectiveness of the proposed processing method and modelling method, and the experimental results show that the roughness of silicon wafer can decrease from 506.71 nm to 10.17 nm by means of the proposed processing method.
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