Ultrasonic assisted grinding is an effective way for trepanning the core rod, but the brittle fracture is the main manner to remove the hard and brittle materials during ultrasonic assisted grinding, leading to dimension error between the rod diameter and the inner diameter of the grinding wheel.Aiming at the above problem, based on the theory of indentation fracture mechanics and the kinematic analysis of diamond grains on the grinding wheel, a prediction model of the rod diameter was established, during which the effects of the expansion of the lateral cracks on the rod diameter were considered at the same time.Subsequently, the model was calibrated and verified through the test of ultrasonic assisted trepanning of core rod of K9 optical glass.The effect of the feed and spindle speed on the rod diameter was studied.The comparison experiment indicates that the simulation results are in good agreement with the experimental results, and the error is within 5%, which verifies the validity of the model.The experimental results show that the diameter error of the core rod can be reduced effectively with lower speed and higher feed rate during ultrasonic assisted grinding.The established prediction model of the rod diameter can offer theoretical guidance to the selection of the grinding wheel for trepanning the core rod with ultrasonic assisted grinding.%超声辅助磨削是一种套料芯棒加工方法,而硬脆材料在超声辅助磨削加工过程中的去除模式主要为脆性断裂,这将导致加工出的芯棒直径与砂轮内径之间存在尺寸误差.针对上述问题,通过分析超声辅助磨削加工中砂轮表面金刚石磨粒的运动轨迹,运用压痕断裂力学理论建立了超声辅助磨削芯棒的直径预测模型.该模型考虑了脆性材料断裂时产生的侧位裂纹扩展对芯棒直径的影响.通过对K9光学玻璃材料进行超声辅助套料试验对模型进行了标定和验证,接着研究了进给速度和转速对芯棒直径误差的影响规律.通过对比研究发现,模型计算结果与试验结果吻合较好,误差小于5%,验证了模型的有效性.试验结果表明,采用适当的低转速和大进给速度可以有效降低超声辅助磨削芯棒直径的尺寸误差.本文所建模型可为超声辅助磨削套料芯棒的砂轮选择提供理论指导.
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