Grinding characteristics of micro tensile test piece ground by form external grinding

摘要

Form accuracy, surface roughness and tensile rupture elongation of the micro test piece produced was examined in order to investigate the influence of machined surface properties on specific strength. High-speed steel, brass, stainless steel, and tungsten carbide were selected for test piece material. The shape of the test piece was 50μm in diameter, 1.5mm in the length of its parallel portion, and 1.0mm in the gauge length. The grinding style was plunge and dry cut with a form wheel by open side support. The wheels were SD400, SD600, SD800 and SD1000 bronze-bonded wheels, which were generated by spark erosion. The diameter of the parallel portion increased as the measuring portion diverged from the chucking point. As well, the diameter of the parallel portion of the test piece of each material was not the 50μm goal dimension but rather 80μm～160μm. As grain size was large, the surface property of the test piece was somewhat rough. Simple tensile rupture machining was used to investigate rupture point and elongation. Each test piece ruptured at both the narrow and rough points.