Fried. Krupp Gesellschaft MIT Beschrankter Haftung

Krupp Widia Gmbh

Alfons Lomberg

Peter Cleve

An extrusion molding tool for the production of a drill blank made of a plastic raw material by extruding the material in a longitudinal extrusion direction across a production mandrel and through a bore in a die, the bore having a longtiudinal axis, the mandrel having at least one elastically deformable wire radially spaced from the longitudinal axis projecting into an intake end of the bore for forming at least one internal helical rinsing bore in the drill blank, wherein the die includes a plurality of annular discs disposed one behind the next in the longitudinal direction. The discs have respective interior surfaces surrounding the longitudinal axis and together define the bore. The interior surfaces have ribs which when properly aligned together form a helical radially inwardly projecting ridge extending at a helix angle with respect to the longitudinal direction to define a means for twisting the raw material passing through the bore. The discs are rotatable relative to one another about the longitudinal axis to adjust the helix angle. Means are provided to adjustably fix the discs against rotation to set the helix angle.

Extrusion molding tool

An extrusion tool for making a drill bit blank provided with an internal rinsing bore extending helically in a longitudinal direction of the drill bit blank, includes a nozzle having an inner wall defining a throughgoing axial bore through which a malleable material is passed in a direction of extrusion parallel to the tool axis. The axial bore forms an inlet portion and a mold chamber adjoining the inlet portion downstream thereof as viewed in the direction of extrusion. There is further provided a mandrel situated in the inlet portion; a resiliently deformable wire supported by the mandrel and projecting into the mold chamber; and a helical device provided on the inner wall in the mold chamber for twisting the malleable material as it passes through the mold chamber. There is further provided a clamping device having a tightened state for immobilizing the nozzle and the mandrel with respect to one another during extrusion operation. In the loosened state of the clamping device a positional adjustment of the nozzle with respect to the mandrel may be made.

Extrusion tool for producing a drill bit blank

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.

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Bottrop, Germany

Alfons Lomberg