微纳V槽脆/塑性域切削的3D激光检测及评价

摘要

针对微纳米级功能V槽微细加工及评价困难的问题,采用单点金刚石切削方法在超精密机床上对光学玻璃进行了V槽的微纳尺度加工,且利用非接触激光检测技术展现了V槽的加工形貌.依靠单晶金刚石的锋锐刃角在光学玻璃上进行V槽的微纳尺度切削试验,利用3D激光超精密检测仪器检测加工的V切痕,构建了微V槽切痕的形貌图,并建立了V槽形状误差PV值和V槽尖角圆弧半径的评价模式.最后,分析了微纳尺度加工中切除深度与V槽角度的形成机理以及切削深度对V槽形状误差及其尖角圆弧半径的作用机制.结果表明,在亚微米级尺度加工中存在一个脆/塑性域切除加工状态转变的临界切削深度0.386 μm.在切削深度＜0.386 μm的塑性域切削中,金刚石刀具尖角形状可以复制到工件表面,形成深度＜0.386 μm、形状误差PV值约为0.103 μm的V槽.此外,由于V槽尖角圆弧半径在塑性域切削中随着切削深度减小而减小,所以切削深度需控制在V槽临界成型深度0.365 μm以下,才能形成尖角半径为0.182 μm的完整V槽.实验也表明,利用非接触激光检测的3D数据建立V槽形状误差PV值和尖角圆弧半径的参数模型,可用于V槽加工精度和微细程度的评价.%To improve the measurement and evaluation methods of a machined micro/nano scale Vshaped groove, a singlepoint diamond turning was employed to machine the Vshaped groove of optic glass in micro/nano scale, and a noncontact laser measuring technology was used to analyze the topography of machined Vshaped groove. The micro/nano scale cutting of the Vshaped groove of optic glass was conducted by using the sharp cutting edge of a single crystal diamond. Then, the machined Vshaped groove was measured by a 3D laser meter to compare its profile,and the evaluation mode of the shape error PV and tip arcradius of the Vshaped groove was established. Finally, the form principle of cutting depth and the angle of Vshaped groove were analyzed and the effect of submicro scale cutting depth on the shape error PV and the tip arcradius was investigated. The results show that there exists a critical cutting depth of 0.386 μm,when cutting mode is transferred from a brittle cutting to a ductile cutting in submicronscale space. In ductile mode cutting with a cutting depth less than 0.386 μm, the diamond tool tip can be replicated to the workpiece surface and to produce a submicroscale Vshaped groove with a cutting depth less than 0.386 μm and a shape error PV about 0.103 μm. In addition, the tip arcradius of Vshaped groove decreases in ductile mode cutting when the cutting depth is decreased, so to get a Vshaped groove with the tip arcradius of 0.182 μm,the cutting depth should be controlled below the critical Vform cutting depth of 0.365 μm. These results also show that the parameterized model of shape error PV and tip arcradius can be established by using 3D data derived from noncontact laser measurement, and can be employed to evaluate the machining precision of microscale Vshaped grooves.