| 摘要 |
The flat-headed countersunk screw is configured as a flat-headed countersunk tapping screw (20) and has a shank (26), provided with a thread, as a wood thread, machine thread or special thread, if appropriate also continuing as far as the head, and a flat head (21), in the top surface (23) of which the tool-attachment means, for example a screwdriver slit (24.1), are provided. The frustoconical part located between top surface (23) and shank is divided into cutting regions (41) and supporting regions (38), the points or cutting edges in the cutting region extending, at most, as far as the lateral cone surface determined by the supporting regions, with the result that they do not penetrate into hard materials, but, in softer materials, they automatically cut the necessary countersinking in the bore. The supporting regions may be configured as annular supporting regions, in particular in the region of the uppermost end and/or as cone-generatrix regions (37). The latter are located between the cutting regions (41). <IMAGE>
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