銅粗大結晶の切削機構

Abstract

This paper describes the crystal-lographical cutting mechanism of large crystals of copper following the preceding work on Fe-3.5%Si. The experiment was conducted under the two dimensional cutting. The large crystals (about 4∼25 mm) were produced by slow solidification in vacuum furnace. The orientation of the crystals were determined by the Laue X-ray back reflection method.The main results obtained are as follows:(1) The {111}〈110〉 slip system is the only one in copper and is classified into the positive and the negative slip system. The ratio of the activated negative slip system to the positive one is 0.1∼0.3 for almost all grains and can be forecast from both the crystal orientation and the cutting direction.(2) In this experiment the specific cutting resistance varied from 41 kg/mm2 up to 93 kg/mm2 depending upon the crystal orientation. This variation is based on both the area of the shearing plane and the work-hardening.(3) In applying the critical cutting angle of annealed polycrystal copper, the thrust force becomes positive for a large shear angle.(4) The cut surface becomes good under a small cutting force.(5) Lamella spacing on the free surface of chip is affected by the situation of chip flow, i.e., it becomes coarser with the increased restriction of chip flow. The direction of lamella is perpendicular to that of chip flow.