| 摘要 |
The invention relates to an extrusion press method for the continuous production of fully cylindrical sintered blanks (24) comprising at least one internal, spirally extending channel (3) having a predetermined cross-section, wherein the plastic material (12) forming the blank (24) is pressed out of the mouth of a nozzle (DZ) of an extrusion press (10) on the outlet side thereof in the form of a substantially circular cylindrical, preferably internally smooth pipe. The plastic material which exits from the mouthpiece of the nozzle (DM) in a substantially twist-free manner flows along the axis of at least one spirally twisted pin (400, 420) which is maintained in a stable position on a gudgeon of the nozzle (18). Said pin protrudes at least sectionally into the mouthpiece of the nozzle (DM). According to the invention, high-precision fully cylindrical sintered blanks can be produced even if the geometry of the cooling channel is difficult to construct. The method is characterized in that the pin (400, 420) does not rotate, the plastic material (12) in the mouth of the nozzle (DM) is displaced in a twisted flow corresponding to the spiral shape of the pin (400, 420) and the rotation movement of the plastic material (12) is supported by a rotationally driven section (140) of the mouth of the nozzle (DM), which is engaged on the outer periphery of the material such that the pin (400, 420) is essentially not subjected to any bending deformation. |
