An extruded drill blank which has uniform pitch of grooves or lands on the circumference thereof and flushing bores of uniform diameter. A tool and process for producing the extruded drill blank comprises heating a hard metal or ceramic material to the extrusion temperature thereof, pressing the heated metal or ceramic material through the space defined by a mandrel and a nozzle and twisting the blank helically during the extrusion, whereby the billet is guided in the direction of the extrusion by at least one land or groove extending helically and provided on the inside surface of the nozzle, and contemporaneously forming bores on the blank with at least one elastic center pin secured onto the mandrel and spaced apart by a spacing corresponding to the flushing bore; the mandrel terminating prior to the nozzle, and the center pin protruding into the nozzle interior and having a diameter corresponding to the diameter of the flushing bores.
申请公布号
DE3600681(C2)
申请公布日期
1990.10.31
申请号
DE19863600681
申请日期
1986.01.13
申请人
FRIED. KRUPP GMBH, 4300 ESSEN, DE
发明人
LOMBERG, ALFONS ALBERT, 4250 BOTTROP, DE;CLEVE, PETER FRIEDRICH, DIPL.-ING., 4300 ESSEN, DE
