Papers by Author: Akira Mizobuchi

Abstract: Hard and brittle materials such as ceramics and glass are not only difficult-to-machine but also occur easily cracks at the exit surface in through-hole drilling. This paper deals with through-hole drilling of glass plate for plasma display panel using an electroplated abrasive grain tool in order to find out drilling conditions for smaller cracks, higher drilling efficiency and longer tool life. In particular, the influence of the crack in two kinds of abrasive grain is examined. The main conclusions obtained in this study are as follows. The crack in diamond grain tool is smaller than that in CBN grain tool. Moreover, the tool life of diamond grain tool is longer than that of CBN grain tool. Adhered volume of chip increases with drilling numbers, so the crack size and the thrust force increases. The washing of tool is required in order to restrain crack and force.

Abstract: Inconel 625® contained Ni 61%, Cr 21.5%, Mo 9% and so on is one of the nickel base super heat resistant alloys and is used for parts in food machine. The nickel base alloys are generally difficult-to-cut materials because of high thermal resistance, high work-hardening, high chemical activity and low thermal conductivity. In tapping, furthermore, the tool failure such as chippings, cracks and tool fractures has been frequently observed owing to low rigidity of tool. This paper deals with the influences of surface treatment, tool geometry etc. on the cutting phenomena such as the tool failure, the cutting force and so on when tapping Inconel 625® using the high speed steel tool. The damage of oxidizing tool is slower than that of nitriding tool. The large thrust force in backward tapping causes the rapid tool fractures. The smaller helix angle leads to the lower thrust force in backward tapping.