| 摘要 |
A drill of the loose top type, which is composed of a basic body and a replaceable loose top. In the front end of the basic body, a jaw is formed, which is delimited by two elastically bendable branches and an intermediate axial support surface, and in which the loose top can be securely pinched by inner support surfaces of the branches being resiliently pressed against side contact surfaces of the loose top. The two side contact surfaces of the loose top extend rearward from clearance surfaces that are included in the front end of the loose top. By forming the diametrical dimension between opposite side contact surfaces greater nearer the front end of the loose top, the branches of the jaw securely pinch the loose top in the area of the front ends thereof, where the branches have their maximal bending capacity.
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