Drill bit

A drill bit (11, 41) for the drilling, in particular the rotary percussive drilling, of a hole, in particular a tap hole of a melting furnace, the drill bit (11, 41) comprising a drill head (10, 42), which has at least one hard material insert (16, 43), and a base body (12) for connecting the drill bit to a driving element, the hard material insert (16, 43) being inserted into a seat (14, 44), which is formed in an axial end face (13) of the drill head (10, 42), in such a manner that at least a head cutting edge (18, 46, 47) of the hard material insert (16, 43) protrudes beyond the axial end face (13), characterized in that the seat (14, 44) has a flank portion (29, 54) and a mating flank portion (30, 51) located opposite the flank portion, between which the hard material insert (16, 43) is disposed, the flank portion (29, 54), which is disposed opposite a recess (33, 49) formed in the hard material insert (16, 43), being provided with a material projection (35, 36, 53) which is at least partially made of a welded material (37), is bonded to the drill head (10, 42) via the welded material (37) and protrudes into the recess (33, 49) so as to establish a form-fitting connection with the hard material insert (16, 43);

• wherein the seat (44) is cylindrical, in particular a drill hole, and the hard material insert (43) has a retaining extension (45) which is substantially complementary to the seat (44) and inserted into the seat (44);
• wherein the clearance (48) formed in the hard material insert (43) has a flat portion (50) adjacent to a shoulder for forming the recess (49), said flat portion (50) extending as far as to a head cutting edge (46, 47);
• wherein the flat portion (50) is disposed in a plane that is disposed at a right angle to the head cutting edge (46, 47);
• and
• wherein opposite the flat portion (50) and above the retaining extension (45), the hard material insert (43) has a radial protrusion (52) which extends in the direction of the head cutting edge (46, 47) and protrudes beyond the mating flank portion (51).

A drill bit (11, 41) for the drilling, in particular the rotary percussive drilling, of a hole, in particular a tap hole of a melting furnace, the drill bit (11, 41) comprising a drill head (10, 42), which has at least one hard material insert (16, 43), and a base body (12) for connecting the drill bit to a driving element, the hard material insert (16, 43) being inserted into a seat (14, 44), which is formed in an axial end face (13) of the drill head (10, 42), in such a manner that at least a head cutting edge (18, 46, 47) of the hard material insert (16, 43) protrudes beyond the axial end face (13), characterized in that the seat (14, 44) has a flank portion (29, 54) and a mating flank portion (30, 51) located opposite the flank portion, between which the hard material insert (16, 43) is disposed, the flank portion (29, 54), which is disposed opposite a recess (33, 49) formed in the hard material insert (16, 43), being provided with a material projection (35, 36, 53) which is at least partially made of a welded material (37), is bonded to the drill head (10, 42) via the welded material (37) and protrudes into the recess (33, 49) so as to establish a form-fitting connection with the hard material insert (16, 43);

• wherein the length of the seat (14) in the drill head (10) extends substantially radially with respect to an axis of rotation R of the drill head (10) and the seat (14) has an opening (26) at the radially outer end, the hard material insert (16), whose length extends in the same radial direction, being accommodated in the seat (14) in such a manner that the hard material insert (16) protrudes beyond a circumferential surface (28) of the drill head (10) by a protrusion (27) which extends radially with respect to the axis of rotation R;
• wherein the radial protrusion (27) of the hard material insert (16) forms a circumferential cutting edge (19) which extends substantially parallel to the axis of rotation R of the drill head (10);
• and
• wherein starting from the head cutting edge (18), which protrudes beyond the axial end face (13) of the drill head (10), the circumferential cutting edge (19) extends beyond the seat bottom (23) of the seat (14) in such a manner that a cutting edge leg (24) of the circumferential cutting edge (19) is accommodated in a second bottom clearance (25) in the seat bottom (23) of the seat (14).