横向超声振动对金刚石线锯切割硬脆材料锯切力及临界切削深度的影响

硬脆晶体材料,如SiC、Ge和Si等,由于其临界切削深度极小,常规加工方法很难实现塑性模式加工,研究横向超声振动金刚石线锯对硬脆材料锯切力和临界切削深度的影响有重要意义。在研究线锯受迫振动的基础上,分析金刚石线锯在横向超声波激励下柔性旋转点切割硬脆材料的条件;用特征函数对超声激励下金刚石线锯的振动切割状态进行表征;应用磨削理论建立了单颗金刚石磨粒切割硬脆材料的力学模型;推导出超声振动激励下金刚石线锯锯切硬脆材料临界切削深度的计算公式。以单晶SiC为对象,进行了超声振动线锯切割和普通线锯切割对比试验。结果表明相同条件下,超声振动线锯切割SiC的锯切力比普通线锯的锯切力减少22.4%~64.2%,临界切削深度增加1倍,晶片表面粗糙度有明显的改善。试验结果与理论分析具有良好的一致性。

Influence of Diamond Wiresaw Excited by Transverse Ultrasonic Vibration on Cutting Force and Critical Cutting Depth of Hard and Brittle Materials

The hard and brittle materials, such as SiC, Ge and Si, are very difficult to cut at ductile mode by conventional machining, because of a extremely small critical cutting depth. Influence of diamond wiresaw excited by transverse ultrasonic vibration on cutting force and critical cutting depth of hard and brittle materials is crucial. Based on analyzing forced vibration of wiresaw, the required conditions that meet the hard and brittle materials rotary cutting at a point in flexible mode by transversely vibrating diamond wiresaw is analyzed and obtained. The characteristic function is used to describe the cutting states of hard and brittle materials cut by transversely vibrating wiresaw. Applying grinding theory, the mechanics model of hard and brittle materials cut by single diamond abrasive particle is established. The formula calculating critical cutting depth of hard and brittle materials cut by transversely vibrating diamond wiresaw is deduced. Comparative experiment of cutting SiC crystals by ultrasonic vibration wiresaw and conventional wiresaw is conducted. The experimental result shows that the cutting force in vibrating wiresaw cutting decreases 22.4%~64.2% than that in conventional wiresaw cutting under the same machining conditions. The critical cutting depth of SiC monocrystals in vibrating wiresaw cutting is double than that in conventional wiresaw cutting. The surface roughness of wafers is improved obviously. Experimental results is consistency with the theoretical analysis.