Abstract: Method and apparatus for the continuous extrusion of rods of plastic raw material. The rods contain at least one inner channel which is at least in part spiral-shaped. The raw material may be a powder-metallurgical or ceramic mass. The material is extruded through a nozzle mouthpiece and made to rotate by an arrangement of flow guiding surfaces. At least one thread made of a flexible or elastic material is entrained and gives the rod a spiral shape with a predetermined pitch. The thread is retained upstream of the nozzle mouthpiece in an eccentric position relative to the rod axis that extends through the nozzle mouthpiece. The movement of rotation of the raw material is adjusted by an outer adjusting force which modifies the angle between the arrangement of flow guiding surfaces and the longitudinal axis of the nozzle mouthpiece to adjust the position and pitch of the spiral channel.

Abstract: An apparatus for manufacturing a rod of hard metal or ceramic with at least one helical inner bore. A plasticized mass of hard metal or ceramic is simultaneously forced through a die and twisted. Either the mass is twisted uniformly over the cross-section of the billet by a spinner immersed in the mass or the spinner is rotated by the mass. The mass emerges either subject to torsion or entirely or mostly without torsion from a smooth downstream channel through the die. A filament-shaped material extends or is injected into the mass to produce the inner bore or bores.

Abstract: An extruder for extrusion manufacturing a rod of hard metal or ceramic with at least one helical inner bore. A plasticized mass of hard metal or ceramic is simultaneously forced through a die and twisted. Either the mass is twisted uniformly over the cross-section of the billet by a spinner immersed in the mass or the spinner is rotated by the mass. The mass emerges either subject to torsion or entirely or mostly without torsion from a smooth downstream channel through the die. A filament-shaped material extends or is injected into the mass to produce the inner bore or bores.

Abstract: An extruder for extrusion manufacturing one of a hard metal and a ceramic rod with at least one helical inner bore and having a smooth outer surface substantially free of elevations and depressions includes a housing and a die connected to the housing. The mechanism for forcing a plasticized mass through the die is provided wherein the mass is shaped in the form of a billet having a cross-section. A spinner is located in the housing upstream of the die for twisting the mass uniformly over the cross-section of the billet, the spinner being surrounded by an axial flow of the mass. A smooth channel is located downstream of the spinner such that the mass emerges from the channel through the die and a mechanism is provided suspending a filament in the mass wherein the filament follows a twisting movement of the twisted mass so as to form a helical inner bore therein.

Abstract: The invention relates to a extrusion die tool for producing a hard metal or ceramic rod with at least one twisted internal bore (14). The nose (3) of the nozzle (2) has a smooth cylindrical channel (4). A bearer (6) is fitted coaxially inside the nozzle (2) which has a plurality of elastic threads (9) and/or channels or bores corresponding to the desired number of internal bores for the thread-shaped pressing of a plastic material into the extruded material. The bearer (6) and the nozzle nose (3) are rotary, i.e. they rotate about their longitudinal axes. The pitch of the twisted internal bores (14) produced is thus determined by the rotation speed of the thread bearer (6) and/or the nozzle nose (3) and the rate of flow of the extruded material. Rod blanks with high-precision helical internal bores (14) can thus be produced.