固结磨料研磨单晶蓝宝石亚表面损伤的预测

目的为了准确预测工件亚表面损伤,合理确定材料去除量,优化固结磨料研磨单晶蓝宝石的工艺参数。方法针对固结磨料研磨特点和单晶蓝宝石特性,采用离散元模拟技术,建立单晶蓝宝石材料的离散元模型,仿真固结磨料对材料研磨的动态过程,分析载荷作用下材料单元颗粒间裂纹的产生和扩展规律,研究磨粒切入深度对亚表面损伤的影响,预测固结磨料研磨单晶蓝宝石亚表面裂纹的数量和深度,并借助化学腐蚀法验证预测结果。结果采用粒度分别为W14、W28、W50、W65的金刚石固结磨料垫,其对应的研磨单晶蓝宝石亚表面损伤层深度预测值分别为3.75、5.28、7.62、10.92μm,预测的裂纹数量分别为199、236、526、981条,对应的实验实测值分别为3.79、5.88、8.76、11.44μm。固结磨料垫中的磨料粒径越大,单晶蓝宝石亚表面损伤层的深度越大,裂纹数量越密集。对比发现腐蚀实验的实测值和理论预测值基本一致,验证了预测结果模型的正确性。结论采用离散元法可以快速有效地预测固结磨料研磨单晶蓝宝石亚表面损伤层的裂纹数量和深度,为研磨工艺参数的优化和后续抛光工艺参数的制定提供指导。

Prediction of Subsurface Damage for Fixed Abrasive Lapping Single Crystal Sapphire

The work aims to accurately predict the subsurface damage of the workpiece,reasonably determine the material removal amount,and optimize the process parameters of the single-crystal sapphire with the fixed abrasive.According to the lapping characteristics of fixed abrasives and the properties of single crystal sapphire,the discrete element model of single crystal sapphire was established by discrete element method,the dynamic process of lapping the material by fixed abrasive was simulated,the generation and propagation of cracks between element particles under load were analyzed,the effect of cut depth of abrasive grains on subsurface damage was studied,the number and depth of subsurface cracks of single crystal sapphire lapped by fixed abrasives were predicted,and the prediction results were verified by chemical corrosion method.The results indicated that with the fixed abrasive pads with particle sizes of W14,W28,W50 and W65,the corresponding predicted depth of the lapped sapphire subsurface damage layers was 3.75μm,5.28μm,7.62μm and 10.92μm;the predicted number of cracks was 199,236,526 and 981;and the corresponding experimental values were 3.79μm,5.88μm,8.76μm,and 11.44μm,respectively.As the abrasive particle size in the fixed abrasive pad increased,the depth of the single crystal sapphire subsurface damage layer and the number of cracks also increased.The comparison showed that the measured values and predicted values were basically consistent,and the correctness of the prediction results was verified.Therefore,the discrete element method can quickly and effectively predict the number and depth of cracks in the sapphire subsurface damage layer of the fixed abrasive,and provide guidance for the optimization of the lapping process parameters and the formulation of subsequent polishing process parameters.