| 摘要 |
<p>The invention relates to a drill of the loose top type, which is composed of a basic body (1) and a replaceable loose top (2). In the front end of the basic body, a jaw (20) is formed, which is delimited by two elastically bendable branches (21) and an intermediate axial support surface (22), and in which the loose top (2) can be securely pinched, more precisely by inner support surfaces (24) of the branches (21) being resiliently pressed against side contact surfaces (26) of the loose top. According to the invention, the two side contact surfaces (26) of the loose top extend rearward from clearance surfaces (28) that are included in the front end (9) of the loose top. By forming the diametrical dimension between opposite side contact surfaces (26) greater nearer the front end of the loose top, the effect is attained that the branches (21) of the jaw securely pinch the loose top in the area of the front ends thereof, where the branches have their maximal bending capacity. In such a way, the branches provide a distinct and reliable grip on the loose top. The invention also relates to a loose top (2) for the drill.</p> |
