Research on Ultra-high Precision High Speed Machining of Steel

本研究的目的是为了证明包括不锈钢在内的钢材的超高精度加工的可行性，并为相关技术的进一步发展做出贡献。从切屑形成、表面完整性、切削力、刀具磨损和失效等方面对CBN刀具超精密飞切钢进行了试验研究。主要结果如下：1.钢的超高精度微加工中的切屑形成和表面完整性不锈钢（JIS：SUS303Se）和碳钢（JIS：S45C和S25C）的超高精度微加工是用特殊研磨的CBN刀具进行的，切屑形成的深度小到1到2 <mu>m。在<mu>不锈钢的情况下，获得了小于0.1 m Rmax的表面粗糙度。钢的超高精度微细加工中的切削力在实验范围内，在三个力分量中，推力最大。切削力的第二大分量是主切削力，进给力最小。推力与主切削力之比为1.6比2。切削力与切削条件的关系不大。根据理论切削截面积计算出的名义比切削力在减小进给量时显著增大. CBN刀具与超高精度机床研究发现，CBN刀具中CBN的含量对刀具飞切钢时的抗破坏能力有很大影响。CBN刀具的粘结剂也起着重要的作用。超高精度机床主轴的刚度直接影响刀具的使用寿命。

The objectives of the research are to prove the feasibility of ultra-high precision machining of the steels including the stainless steel and to contribute for further development of the relevant technologies. Experimental investigations were carried out on the ultra-precision fly cutting of the steels with CBN tools from the viewpoints of the chip formation, the surface integrity, the cutting forces and the wear and failure of the tool etc.. The major results obtained are as follows;1. Chip formation and surface integrity in ultra-high precision micro machining of steel The Ultra-high precision micro machining of stainless steel (JIS: SUS303Se) and carbon steels (JIS: S45C and S25C) were carried out with specially ground CBN tools and the chips were formed at small depth of cut down to 1 to 2 <mu> m. The surface roughness of less than 0.1 <mu> m in Rmax was obtained in the case of the stainless steel.2. Cutting forces in ultra-high precision micro machining of steel The thrust force was found to be maximum among the three force components within the range of experiments carried out. The second largest component was the main cutting force and the feed force was smallest. The ratio of the thrust force over the main cutting force was 1.6 to 2. The cutting forces do not depend much on the cutting conditions. The nominal specific cutting force calculated based on the theoretical cross sectional area of cut was found to be increased extremely at reduced feed rate.3. CBN tool and ultra-high precision machine tool It was found that the contents of CBN in the CBN tool much affect the failure resistance of the tool in fly cutting of the steel. The binder of the CBN tool also plays an important role. The rigidity of the main spindle of the ultra-high precision machine tool influences the tool life.