Strangpreßwerkzeug zur Herstellung eines Hartmetall- oder Keramikstabes

摘要

The invention relates to a process for producing a hard-metal or ceramic bar which has at least one helical internal hole (16) and a smooth outer surface. The plasticised extrusion compound is forced through a die (2) with a smooth bore (4). Arranged within the die (2) is a twisting device (8). This twisting device (8) imposes a twisting motion on the extrusion compound or, alternatively, a rotation is imparted to the twisting device (8) by the extrusion compound. Filiform material, e.g. elastic threads, project into the flow of compound, or filiform material is injected into the flow of compound via the channels 11, 12, 15. This material follows the twisting or rotary motion and produces the helical internal holes (16). The extrusion tool has an internal mandrel (6) on which the twisting device (8), which is designed as a twisting screw, is arranged rotatably or in a manner fixed against rotation. The die nozzle (3) can also be of rotatable design.