DRILL BIT FOR ROCK DRILLING

摘要

A drill bit for rotary impact drilling of reinforced concrete comprises a shank having brazed to one end thereof a cutter ring. An ejection passage for removing drilling ? has a first section extending axially through the cutter ring and shank end, and a second section opening to the helical outlet grooves on the surface of the shank. The second section can be in the form of a slot of a radial bore through the shank. In one arrangement the second section is formed by two opposed radial bores at an acute angle to the drill axis which meet in a chisel edge within the shank. This chisel edge serves to fi?gment the standing core which remains within the cutter ring.