Si_(3)N_(4)陶瓷纵扭超声磨削表面残余应力及其试验研究

Test study on surface residual stress of Si_(3)N_(4) ceramic using LTUVAG

Si_(3)N_(4)陶瓷属于典型的硬脆材料,已加工表面易产生微裂纹,对陶瓷零件的使用性能影响较大。为获取高性能的Si_(3)N_(4)陶瓷零件,纵扭超声磨削被应用于其超精密加工中,为揭示纵扭超声振动磨削对Si_(3)N_(4)陶瓷零件独特的加工机理,建立了纵扭超声磨削单颗磨粒切削轨迹方程及其磨削表面残余应力模型,并进行Si_(3)N_(4)陶瓷纵扭超声磨削试验验证。结果表明:相同加工工艺参数下,普通磨削Si_(3)N_(4)陶瓷表面残余应力多为拉应力,而纵扭超声磨削Si_(3)N_(4)陶瓷表面多为残余压应力,进而纵扭超声磨削Si_(3)N_(4)陶瓷亚表面损伤深度比普通磨削最大可降低38%,且其理论仿真结果与试验结果误差不超过10%,可为Si_(3)N_(4)陶瓷高性能零件的超精密加工提供新的加工方法。

Si_(3)N_(4) ceramic is a typical hard and brittle material,so it is easy to produce microcracks on its machined surface,these microcracks have larger effects on usage performance of ceramic parts.To obtain Si_(3)N_(4) ceramic parts with high-performance,longitudinal-torsional ultrasonic vibration assisted grinding(LTUVAG)is applied in their ultra-precision machining.Here,to reveal the unique machining mechanism of LTUVAG for Si_(3)N_(4) ceramic parts,the cutting trajectory equation of single abrasive particle during LTUVAG and the residual stress model of its machined surface were established,LTUVAG test verification of Si_(3)N_(4) ceramic was performed.The results showed that under the same processing parameters,residual stress on machined surface of Si_(3)N_(4) ceramic using ordinary grinding is mostly tensile stress,while residual stress on machined surface of Si_(3)N_(4) ceramic using LTUVAG is mostly compressive stress;the sub-surface damage depth of Si_(3)N_(4) ceramic using LTUVAG can be reduced by up to 38%compared to that using ordinary grinding,the error between theoretical simulation results and test results is not more than 10%;the proposed LTUVAG can provide a new machining method for ultra-precision machining of Si_(3)N_(4) ceramic parts with high-performance.