Design of a New Tool in Drilling Deep Steps Helly Hole

In order to drill a deep steps hole with a big belly in hard-cutting material parts, a special boring cutter is designed by analyzing cutting technology of this kind of parts. On the basis of single-tube inner chipremoval ejector drill (SIED), a new tool radical movement mechanism is pulled by a wedge plate installed inside the tool rod at one end of the rod and plate is driven horizontally by a motor controlled by a numerical control device. A straight hole whose diameter is same as the minimum one of the steps holes is firstly machined by an entity drill. And then the tool is used to get the big belly hole in the middle of the straight hole and begin to move radically at the same time as axial feed just in the location of belly. The tool is retreated to the original position at the end of the big belly. Experiments show that this kind of tool can not only drill belly holes effectively but also improve the processing quality.