| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a twisted section in excellent dimensional accuracy as well as one intermittently twisted in its longitudinal direction, or one twisted in an uneven pitch rather than an even pitch. SOLUTION: A forming die apparatus is comprised of a stationary guiding die which is fixed to an opening at an exit side of a container for raw material, in a ring shape, having a spiral guide on the inside surface, and a movable die which has an extrusion forming hole and is inserted movably along the spiral guide into the stationary guiding die. The extrusion forming method of twisted section is characterized in that it pressurizes material contained in the container to force it out from the extrusion forming hole of the movable die, moving the movable die along the spiral guide to give the movable die a screwing motion, and then extrusion-forms the twisted section whose phase in a cross section perpendicular to the longitudinal direction of the twisted section varies along the longitudinal direction of the same.
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