NZ536160A - Rotary hammerdrill bit - Google Patents

Abstract

The invention relates to a rotary hammerdrill bit for use with a percussion drilling device or a hammer drilling device, with a shank and a drill head attached to or configured on the shank, wherein on its front side pointing in the advance direction the drill head has a main cutting plate forming a main cutting axis. The main cutting plate extends at least over the diameter of the drill head, has a tip or tip-edge lying in the longitudinal axis of the drill bit and forms drill blades that are extending substantially roof-shaped at an incline radially from the tip or tip-edge. On its front side pointing in the advance direction the drill head also has at least one pair of cutting pins, wherein the cutting pins are arranged on the drill head in essentially the same radial positions, and are arranged on both sides of the main cutting plate substantially symmetrically at a specific angle of less than 90 DEG to the main cutting axis. The drill blades each have a recess extending against the advance direction in the region of the rotation surface defined by the cutting pins. The rotation surface defined by the cutting pins projects in the advance direction beyond the rotation surface defined by the drill blades as such without considering the recesses, by approximately 0.1 mm to approximately 1.0 mm.