Rock drill boring head - has keyhole-shaped cutter inserts with radial extensions projecting from side of boring head (NL 27.6.78)

摘要

A rock drill has a boring head (9) which can be cylindrical with flutes down it, and with a sloping face with holes (15) drilled in it, into which are inserted cutting tips (10, 11). An inner set of tips (10) can be cylindrical, and an outer set (11) may have cylindrical bodies with radial extensions (13, 18) which project beyond the dia. of the head. Thus, in end elevation, the outer cutters are keyhole shaped and their bodies are parallel to the body of the head. In side elevation, the pointed tip is formed by two sloping flats. In an alternative design, a ring shaped cutter (16) has a set of only one type of inserts (17) based on the keyhole design, but with two radial extensions (18) which thus project inwards and outwards from the ring.