| Research Abstract |
The machine finish accuracy of the glass used abundantly in magnetism, electron and optical glass components, roughness of finished surface of angstrom order and 0.1μm/φ100 or less of flatness are required. The purpose of this study did not remain in productive improvement goal of mere accuracy experiment, and it is examined including the energy reduction of processing and the relation facility of minimizing of machining environment space such as reduction of the machining process, construction of circulation regeneration system of machining fluid, clean room, etc., and global environmental load off is considered. At the beginning to clarify the mechanical property of test glasses, micro indentation-scratching experiments in the air and in a SEM are conducted. As a result, critical depths of scratching on several types of glasses are clarified . In continuing, ultra-precision grinding experiments have been conducted on several types of test glasses by using developed multipurpose machine tool, and super smooth finished surfaces in sub nanometer order are obtained. The relationship between machining parameters and microcracks was examined and brittle to ductile grinding transition has been established for a given types of glasses, as well. Besides, a comparison of the recent grinding results and a results of diamond indentation-scratching experiments of previous work done by the authors has shown that the critical depth in grinding is thereabouts six times bigger than the critical depth in indentation and seven times than in scratching. It is clarified that by using developed multipurpose machine tool, from rough processing to the super-finishing is realized without using lapping and polishing machine.
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