Experimental Study on Grinding Silicon Carbide with Small Diameter Diamond Grinding Wheel
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摘要: 【目的】为实现碳化硅陶瓷高质量低损伤磨削加工。【方法】现使用小直径金刚石对碳化硅陶瓷开展磨削实验,依据实际砂轮形貌特征以及现在磨削理论建立磨粒未变形最大切屑厚度模型和亚表面损伤深度模型,并分析磨削切厚对磨削质量、磨削力以及亚表面损伤影响趋势,验证模型的准确性。最后结合有限元仿真,进一步揭示磨粒未变形最大切屑厚度对磨削碳化硅陶瓷表面成型机制的影响。【结果】考虑砂轮与材料表面充分接触,当砂轮线速度5.23m/s、进给速度10mm/min以及磨削深度为20μm时,此时工件表面粗糙度达到最低,为0.3865μm,并且此时磨削力工件亚表面损伤深度也达到最低,仅为4.959μm;当砂轮线速度3.41m/s、进给速度40mm/min以及磨削深度为30μm时,此时磨削力最大,为9.35N,表面沟槽残余高度达到最小,仅为4.85μm,工件表面粗糙度以及亚表面损伤达到最大,分别为Ra=0.7641μm和7.453μm。将LI模型计算亚表面损伤深度与实验值对比,其中最大误差为16.04%,其他结果的误差低于15%。【结论】表面沟槽残余最大高度不仅与磨削力有关,同时也与磨削时参与加工磨粒数目有关,随着砂轮进给速度、线速度以及磨削深度的增加不断减小;表面粗糙度、亚表面损伤主要与磨削切厚以及磨削力有关,二者变化趋势相同,随着砂轮进给速度和磨削深度的增加而增大,随着砂轮线速度的提高而减小,为得到加工后良好表面质量,需提高砂轮线速度,降低进给速度以及磨削深度。磨削切厚模型以及LI亚表面损伤模型基本正确,与实验数据变化趋势相同。在实验所选磨削工艺参数下,磨粒实际磨削切厚在碳化硅陶瓷临界切屑厚度的[-31.86%,13.95%]领域内,即材料去除方式介于塑性去除以及脆性去除之间,证明通过控制磨粒未变形最大切屑厚度可以实验材料的塑性域去除从而减小磨削产生的亚表面损伤。Abstract: 【Objective】To achieve high-quality and low-damage grinding of silicon carbide ceramics. 【Method】 Small diameter diamond was used to conduct grinding experiments on silicon carbide ceramics. Based on the actual morphology characteristics of the grinding wheel and current grinding theory, a model for the maximum undeformed chip thickness of the abrasive particles and a model for the depth of subsurface damage were established. The influence trend of grinding cutting thickness on grinding quality, grinding force, and subsurface damage was analyzed to verify the accuracy of the model. Finally, combined with finite element simulation, the influence of the maximum undeformed chip thickness of abrasive particles on the surface forming mechanism of silicon carbide ceramics during grinding is further revealed. 【Result】 Considering full contact between the grinding wheel and the material surface, when the grinding wheel has a linear speed of 5.23m/s, a feed rate of 10mm/min, and a grinding depth of 20 μ When m is reached, the surface roughness of the workpiece reaches its minimum, which is 0.3865 μ m. And at this time, the sub surface damage depth of the grinding force workpiece also reaches the lowest, only 4.959 μ M; When the grinding wheel has a linear speed of 3.41m/s, a feed rate of 40mm/min, and a grinding depth of 30 μ At m, the maximum grinding force is 9.35N, and the residual height of the surface groove reaches the minimum, only 4.85 μ m. The surface roughness and sub surface damage of the workpiece reach their maximum, with Ra=0.7641, respectively μ M and 7.453 μ M. Comparing the calculated sub surface damage depth of the LI model with experimental values, the maximum error is 16.04%, and the error of other results is less than 15%. 【Conclusion】 The maximum residual height of surface grooves is not only related to grinding force, but also to the number of abrasive particles involved in grinding. It decreases continuously with the increase of grinding wheel feed rate, linear speed, and grinding depth; The surface roughness and sub surface damage are mainly related to the grinding thickness and grinding force, and their changing trends are the same. They increase with the increase of the grinding wheel feed rate and grinding depth, and decrease with the increase of the grinding wheel linear speed. In order to obtain good surface quality after processing, it is necessary to increase the grinding wheel linear speed, reduce the feed rate and grinding depth. The grinding thickness model and LI sub surface damage model are basically correct and have the same trend as the experimental data. Under the selected grinding process parameters in the experiment, the actual grinding thickness of the abrasive particles is within the range of [-31.86%, 13.95%] of the critical chip thickness of silicon carbide ceramics, indicating that the material removal method falls between plastic removal and brittle removal. This proves that controlling the maximum undeformed chip thickness of the abrasive particles can remove the plastic domain of the experimental material and reduce the subsurface damage caused by grinding.
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