GESTEINSBOHRER.

摘要

The rock drill bit is particularly for a hammer-drill, having a single- or twin-start spiral shank, and a roof-shaped main cutter plate with cutting edges and of tungsten carbide or similar material, extending over the full dia. of the bit head. At right angles to this plate are auxiliary cutter plates, pref. in several sections, so as to form a cruciform cutter head. In side view, each auxiliary plate (7,8) to the side of the main one (4) is roof-shaped, an obtuse angle (beta) being formed at its apex (16).