| 摘要 |
<p>The invention relates to an indexable insert drill having a drill body (1) equipped with a peripheral cutting insert (3) and a centre insert (2), which is mounted in a centre pocket (11) that is delimited by a bottom surface (14), a rear end support surface (16), a side support surface (15) of a partition wall (24), and the inside of a border (13) adjacent to the envelope surface (6) of the drill body. The centre insert (2) has an elongate basic shape and includes chip-removing cutting edges (35) at opposite short ends, longitudinal side contact surfaces (36) extending between opposite end surfaces. According to the invention, an inclined intermediate surface (39) is formed between each long side surface and an end surface, which intermediate surface imparts a tapering shape to the end portions of the cutting insert. In addition, the centre pocket (11) is inclined at a moderate acute angle to the centre axis (C1) of the drill body. In such a way, the drill can be made with an extremely small holing diameter without the strength and functionality of the centre insert and the drill body, respectively, being jeopardized. In addition, the invention relates to a centre insert as such.</p> |
