| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
In order to obtain the defect free surface in machining, both the generation of cracks and their propagation should be restrained. For restraining crack generation, a surface energy and/or fracture toughness in crack tip should be increased at machining.
For defect free machining of brittle materials an effect of cutting fluids on mechanical characteristic of soda lime glass-one of homogeneous brittle materials-is firstly discussed. The mechanical characteristics and defect level of brittle materials are quantitatively estimated and discussed by both 4 point bending test and micro Vickers indentation test combined with Weibull's distribution.
Mechanical characteristics of glass are greatly affected by machining fluids. In water, where OH-ion is contained, both fracture stress and its toughness are greatly decreased and, in machining many uncontrollable cracks are easily generated and propagate. The other hand, both the fracture stress and its toughness become lager in spindle oil than th
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ose in water, and both crack generation and its propagation are also restrained in spindle oil than in water. The absorption of OH-ion on surface of glass will decrease fracture stress and/or fracture toughness and surface energy as well.
For increasing of fracture stress and/or its toughness a surface of glass is plated my metal. The fracture toughness of metal plated glass becomes high than that of no plated one. In order to diffuse a metal and/or metal ion into a glass and also to increase the toughness in deeper region of glass, a high electric field is applied for metal plated glass. The fracture toughness increases in deeper region compared with that of only plated one.
Finally for improvement of machinability of glass without pre-plating of metal, a high electric field is applied between glass and metal in machining. It is clearly shown that the application of high electric field between work and metal is very effective the decreasing of defect in machining with water, but not so useful with spindle oil, and also the application gives same effect of metal plating before machining. Less
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