Patent ID: 6926104

Claim:
A drill bit for rotary percussion drilling a tap hole of a blast furnace, wherein the drill bit is comprised of a drill head including a plurality of hard-material or hard-metal inserts and a base body to be connected with a driving element for actuating or powering the drill bit, said hard-material or hard-metal inserts being received in bores or openings of the drill head, wherein at least one hard-material or hard-metal insert, on its end received within the drill head, is at least partially designed with a curved or cambered surface contour that cooperates with a complementary, cambered or curved surface of the drill head and/or the base body, wherein the end of the hard-material or hard-metal insert, which is designed with said cambered or curved surface contour has external dimensions larger than those of the end of the hard-material or hard-metal insert projecting out of the drill head, and wherein the hard-material or hard-metal inserts are capable of being fitted into the bores or passage openings from the drill head side facing the base body of the drill bit, and that the drill head is capable of being connected with the base body upon reception of the hard-material or hard-metal inserts.