| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that in a drill which perforates a work-piece, reduction in time for cutting processing, improvement in rigidity of the drill, and prevention of breakage of the drill caused by a failure in cut chip exhaust and winding of cut chips are desired.SOLUTION: Cutting edges (4) are formed of intersecting lines (4) between flank faces (6) constituted of an end face (2a) of a tip part (2) of a drill (1) and rake faces (7) continuous to cut chip exhaust grooves (5). On the rake faces continuing from the intersecting line are formed parallely recessed curvilinear cross sections (17), whose cross sections are curvilinear, which continue from recessed curvilinear parts of the intersecting lines and are in the same straight line and preferably in a direction parallel to a shaft direction of a rotary shaft (Qr), so that the intersecting lines on the flank face are formed in a shape in which two or more recessed curvilinear parts (15) recessed toward a rotating direction are consecutively arrayed, and have a shape in which one or more protruding parts (16) formed by directly connecting ends of the adjacent recessed curvilinear parts protruding in the rotating direction to each other are formed.SELECTED DRAWING: Figure 1 |
