| 摘要 |
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.
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