小径ダイヤモンド電着工具によるアルミナセラミックへの通し穴加工(第1報) : 工具形状と加工条件の検討

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In through hole drilling of hard and brittle materials such as ceramics, glass etc., cracks occur at the exit surface. This paper deals with a miniature drilling of Al_2O_3 (1600HV) using an electroplated diamond tool. The main purpose of this research is to find out tool geometries and drilling conditions in which the exit cracks are very small and the tool life is very long. A tool with rectangle section and bowl end is effective on the chip removal and the control of fracture size. A method assisted by step feed, in addition, produces a numerous drilling number of 100th or more at a workpiece with a thickness of 3.4mm. The desirable drilling speed should be 50-100m/min and the preferable feed rate arrangement should be 5mm/min at the entrance while 1.5mm/min at the exit. When the tool end reaches the position about 40μm from the exit surface, a hole passes through and large cracks occur around the hole. At the same time, the thrust force falls rapidly. As the tool end moves further, the hole diameter increases and the fracture size decreases. However, large cracks may occur rarely in the progressive process.
社団法人精密工学会の論文
2005-01-05