硬脆機能材料の高静水圧環境における延性モード切削 第２報 高静水圧環境における種種の硬脆材料の切削実験

Abstract

This paper reports results of machining tests under high hydrostatic pressure, 400MPa, done on four kinds of hard brittle materials; soda glass, quarts glass, quarts, silicon. They were examined by a newly developed machining device that consists of a pressure vessel in which a turntable and a tool stage mechanisms are installed. In the machining tests, end surface of the specimens were machined with a single point diamond tool, and tangential cutting force was measured. The examined specimens were observed with a laser microscope, and profiles of machined grooves and the crack ratio were measured. Results show that external hydrostatic pressure is effective to decrease machining defects and to increase the critical groove section area, which indicates limit of machining volume where no machining fracture arises. Tested materials were separated into two groups based on characteristics of the machining fracture; one is soda glass and quartz glass, the other is quartz and silicon. The former group of materials show steep increase of crack ratio by the increase of groove cross section area, but show small increase of the critical groove section area with the increase of external hydrostatic pressure. Besides the latter material group shows gradual increase of the crack ratio, but large increase of the critical groove section area. The difference of these characteristics depends on difference of crystalline structure. Variation of tangential cutting force was also studied, and results show that cutting force increases with hydrostatic pressure. Magnitude of the effect differs with material.