EXTRUSION DIE FOR MANUFACTURING A DRILL BLANK OF HARD METAL OR CERAMICS

摘要

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.