Simulation Analysis of Ultra-fine Machining Process in Single Crystal

单晶超细加工过程的仿真分析为了加工出具有超高精度和表面质量的产品，超精密加工机床正在研制中。同时，超精密加工也是一种精细加工，其加工过程必须看作是对单晶的不同平面和不同取向的加工。为了观察单晶的细切削过程，设计并制作了一台能在扫描电子显微镜下对单晶进行微切削的装置。通过对细切削过程的观察，发现切屑是连续形成的，其过程可视为单剪切面切割模型。切削角、前刀面摩擦角和切削力随晶体方向变化。然而，如果每个晶体方向的摩擦角都是可控的，则可以基于晶体滑移理论和/或各向异性塑性流动理论来预测剪切角。通过对不同变形方向的单晶进行剪切实验，介绍了基于滑移理论的单晶加工硬化特性。利用得到的流动特性，给出了前刀面的摩擦特性。模拟方法。基于各向异性塑性流动理论、单晶流动特性和前刀面摩擦特性，提出并验证了单晶切割工艺。

Simulation Analysis of Ultra-fine Machining Process in Single CrystalIn order to machine products with Ultra-high accuracy and surface qualities, ultra-precise cutting machine tools are being developed. The ultra-precise cutting is, at the same time, a fine machining.The cutting process must be considered as a machining of a single crystal with different plane and orientation.1. In order to observe fine cutting process of a single crystal, a micro cutting apparatus, which is able to cut a single crystal in a SEM, is designed and built. Through the observation of fine cutting process by the apparatus, it was seen that a chip is formed continuously and the process may be considered as a single shear plane cutting model.2. The shear angle, friction angle on a rake face and cutting forces change with directions of the crystal. The shear angle, however, may be predicted based on both of a crystal slip theory and/or an anisotropic plastic flow theory if the friction angle for each crystal direction are in hand.3. The work hardening characteristics of a single crystal based on slip theory is introduced through shearing experiments on single crystal for different direction in deformation. The friction characteristics on the rake face is also proposed by using the obtained flow characteristics.4. The simulation method. for cutting process of a single crystal is finally proposed and verified, which is based on the anisotropic plastic flow theory, the flow characteristics of a single crystal and the friction characteristics on the rake face.