Cutting portion of a drill bit

摘要

The cutting head consists of a cylindrical body (1) with a central diametrical cutting plate (4), and two other cutting plates (5, 6) on either side of the central one so that the three plates lie inside the same circle and form at least four concentric guide points. The three cutting plates are fixed by brazing in grooves in the cutting head, with the two side plates set parallel to the central one and at equal distances from it. The two side plates can be set parallel to one another but at an acute angle - up to 20 degrees - to the central plate. All three plates are pentagonal in shape, with the two side plates of smaller dimensions than the central one.