Drill bits and machining methods

Abstract

The drill bit provided by the present invention makes it less prone to damage at the outermost periphery of the drill tip with a drill edge surface. The drill bit (1) includes: a cylindrical tool body (2), two or three drill tips (3), a drill groove (4), a planar drill edge surface (20), a planar shoulder surface (22), and a straight residual line portion (24). Two or three drill tips (3) are formed at the front end of the tool body. The drill groove (4) is recessed in the outer periphery of the tool body to form the drill lip (11) of the drill tip. The planar drill edge surface (20) is formed by chamfering the drill lip of the drill tip and the edge portion between the drill tip and the cutting edge back (12, 13) of the drill tip. The planar shoulder surface (22) is formed by chamfering the cutting edge formed by the drill edge surface, the outer periphery of the tool body, and the cutting edge back. The straight residual line portion (24) is formed by the drill edge surface and the edge of the outer periphery of the tool body. The drill tip diameter is less than 3mm, and the shoulder width is 15% to 75% of the drill edge width.

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