難削指数による難削性の評価

抄録

This paper deals with Difficult-to-Cut Rating (DTCR) which is a coinage proposed by the authors. DTCR is a rating of difficulty in machining, and it can be calculated from the mechanical and thermal properties of a work material. DTCR has good relation to the inverse of machinability rating (MR). Difficult-to-cut material, such as Ni base alloy, Ti alloy or Hardened steel, has been widely used these days not only in the aerospace industry but also in the public welfare industry. The aerospace industry has a large quantity of the machining data about difficult-to-cut material, while the public welfare industry has limited data. An accurate grasp of its machinability is essential to machine the material successfully. To calculate DTCR, a radar chart composed from four properties, hardness, tensile strength, elongation and thermal character, of a work material is used. As for thermal character, conductivity, specific heat and density of the work material are used. These four properties have an effect on tool life, cutting forces, cutting temperature, surface finish and chip shape. The radar chart gives a feature of the work material, therefore, the rough strategy about machining can be estimated from the chart.