2002 Fiscal Year Final Research Report Summary
High Efficient and High Quality Machining of Optical Glass by Ductile Mode Grinding
| Project/Area Number |
13650788
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Hiroshima Kokusai Gakuin University |
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Principal Investigator |
SUMOMOGI Tsunetaka Hiroshima Kokusai Gakuin University, Faculty of Engineering, Professor, 工学部, 教授 (10136129)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Toshiro Hiroshima Kokusai Gakuin University, Faculty of Engineering, Professor, 工学部, 教授 (60069200)
NAKATA Mikiko Hiroshima Kokusai Gakuin University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (60237302)
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| Project Period (FY) |
2001 – 2002
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| Keywords | nano-scale machining / ductile mode machining / optical glass / ductile-brittle transition / surface crack / subsurface crack / scanning force microscope / scanning laser microscope |
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| Research Abstract |
The studies on nano-scale machining of brittle materials, such as silicon and glass, have come into notice in recent years. A material removal with plastic deformation, known as ductile mode machining, has been achieved by a very small depth of cut. When surface cracks occurred with being increased the depth of cut, the machining has been commonly considered to be brittle mode. The workpiece material used in the present experiment is a optical glass (BK7). A single crystal Vickers diamond pyramid indentor with an apex angle of 136° is used as the cutting tool. The ultra precision turning machine consists of an aerostatic bearing spindle for workpiece revolution and a roller bearing slide for tool feed. Face-turning of the workpiece is done from the center to the outside with a constant cutting speed between 150 m/min and 1500 m/min and a constant feed rate of 0.03 mm/revolution, and a spiral groves are formed. An inclination is given to the mounted workpiece by a partly inserted spacer
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between the workpiece and the chuck surface in order to generate various depth of grooves. The ductile-brittle transition points are examined by the observations not only on the surface cracks but also on the subsurface cracks. A scanning force microscope is used for measuring the depth of the grooves and observing the surface cracks. The distance from the surface to the deepest point of the subsurface crack on obliquely sectioned and then etched surfaces are measured by a scanning laser microscope. The subsurface cracks are generated at a depth of a few nm, while the transition point based on the surface crack would be a depth of 400-700nm. The surface crack on optical glass expands suddenly over the transition point, while the surface crack on single crystal silicon expands gradually. It is detected that the ductile-brittle transition point determined by the subsurface cracks is shallower than that determined by the surface cracks. Therefore the evaluation of the subsurface cracks would be important especially in finishing, Less
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