Study on Ultra-Precision Machining of Hard to Machine Materials

研究的目的是开发难加工材料的超精密加工新技术，促进相关技术的进一步提高。在超精密机床上对不锈钢和几种陶瓷材料进行了飞切试验。在此基础上，进行了超精密二维微细加工实验和扫描电子显微镜（SEM）微细加工实验，分析了切屑形成过程。在整个切削试验中，检查了表面完整性、切削力和刀具磨损。主要结果如下：1.采用不同CBN含量的CBN刀具对不锈钢进行了超精密飞切试验。从刀具磨损和表面粗糙度的角度来看，证明了含有20 - 40% CBN的CBN刀具是最合适的。最大的表面粗糙度为0.1至0.3米获得了高达1000米的切割距离。采用CBN刀具对不锈钢进行了切削深度小于0.1m的微细加工试验。通过对切削过程、表面粗糙度和切屑形成过程的观察，讨论了CBN刀具的晶粒度、粘结剂和抛光对切削过程的影响.对可加工陶瓷、氧化铝陶瓷和氧化锆陶瓷进行了金刚石超精密切削试验。在氧化锆陶瓷的情况下，作为连续切屑形成的结果，获得镜面。实践证明，在氧化锆陶瓷的切削中，采用高刚度的机床和单晶金刚石刀具，切削距离可达1000 m，切削稳定性好，表面质量好。获得的最佳表面粗糙度为0.02 μ m，Rmax。

The objectives of the reserach are to develop new ultra-precision machining technologies of hard to machine materials and to promote further enhancement of related technologies. Fly cutting of stainless steel and several ceramics were carried out on an ultra-precision machine tool. Experiments of ultra-precision two dimensional micro-machining and micro-machining within SEM(Scanning Electron Microscope) were also carried out to analyze the chip formation process. Surface integrity, cutting forces and tool wear were examined throughout the cutting tests. The major results obtained are as follows;1. Ultra-precision fly cutting of stainless steel was carried out with various CBN tools containing different percentages of CBN grains. It was proved that the CBN tool containing 20 to 40 % of CBN is most appropriate from the viewpoints of tool wear and surface roughness. Maximum surface roughness of 0.1 to 0.3 m was obtained up to the cutting distance of 1000m.2. Micro-machining tests of stainless steel with CBN tool were carried out for the depth of cut smaller than 0.1 m. The effects of grain size, binder and polishing of CBN tool were discussed based on the observations of the cutting process, the surface roughness and the chip formation process.3. Ultra-precision diamond cutting tests of machinable ceramics, Alumina ceramics and zirconia ceramics were carried out. The mirror surface was obtained in the case of Zirconia ceramics as a consequence of continuous chip formation. It was proved that the stable cutting was continued and good surface quality was obtained up to a cutting distance of 1000m in the case of Zirconia ceramics when the machine tool with higher rigidity and the single crystal diamond tool were employed. The best surface roughness obtained was 0.02 m in Rmax.