High Accurate Machining of Thin Wall Shape Workpiece by End Mill (Proposal of Twin Spindle Type Machining and Some Experiments)

摘要

It is very difficult to machine the side surface of a thin wall workpiece with precision using an end mill, because the deflection of the thin wall workpiece due to the cutting force is much larger than that of a thick wall workpiece. Then usual cutting conditions under low feed and small depth of cut are used in order to control machining accuracy. But it is impossible to avoid low productivity in this case. Therefore, in this study we propose a new cutting method, we call twin spindle type machining. With this method, we are able to machine the side surface of a thin wall workpiece with high accuracy, ensuring in the same time high productivity. The new cutting method needs two end mills of the same radius and helix angle, however, one of the mills should be right-edge and right- helix cutter while the other one should be left-edge and left-helix cutter. Under this method we may expect that the deflection of the thin wall workpiece due to the cutting force can be neglected because the same cutting force appears on the both sides of the wall surface. We produced a prototype equipment for twin spindle type machining and carried out some experiments. The effects of the new cutting method were confirmed by the results from cutting force and machining accuracy measure- ments.