End mill

Abstract

To provide an end mill for hole drilling by helical processing that has small thrust force and can perform hole drilling with high processing efficiency.SOLUTION: An end mill 1 is configured to specialize in hole-drilling by helical processing, where a middle base angle α showing a gradient of middle bases of end cutting edges 11 is formed at 15° or more and 45° or less. When the middle base angle α is made larger, a region where the end cutting edges contact a work-piece becomes narrower, so that a region where a circumferential velocity in the vicinity of centers of the end cutting edges 11 is low cannot be used for processing. Although thrust force becomes larger when processing is performed in the region where the circumferential velocity is low, the region where the circumferential velocity in the vicinity of the centers of the end cutting edges 11 is low is not used for processing in the end mill, which can reduce thrust force.SELECTED DRAWING: Figure 1

Claims

1. An end mill used for hole machining by helical machining, characterized in that the mid-bottom angle is formed to be between 25° and 45°.

2. The end mill according to claim 1, characterized in that the mid-bottom angle is formed to be 30° or more and 45° or less.

3. The end mill is characterized in that the helix angle of the outer cutting edge is 15° or more and 45° or less, as described in claim 1 or 2.

4. The end mill according to claim 1 or 2, characterized by having a coolant introduction hole aligned with the axis.

Images