Variable section extrusion die set and variable extrusion molding method

摘要

PCT No. PCT/JP96/00647 Sec. 371 Date Nov. 14, 1996 Sec. 102(e) Date Nov. 14, 1996 PCT Filed Mar. 14, 1996 PCT Pub. No. WO96/28264 PCT Pub. Date Sep. 19, 1996By using a variable section extrusion die set which includes a die set (24) displaceable in a first direction orthogonal to an extrusion direction of a molding material and in a second direction perpendicular the first direction and adapted to vary an area of an extrusion molding hole (31) through which the molding material is extruded, and a mandrel (27) reciprocally movable in and out of said extrusion molding hole in the extrusion direction and provided on an outer peripheral portion thereof with a tapered portion (27B) which is gradually reduced in outer configurational dimension from one direction of the reciprocally moving direction to the other, said die set being moved to deform the extrusion molding hole (31) while pressing the molding material against said die set (24), and the tapered portion of the mandrel (27) being reciprocally moved in and out of the extrusion molding hole, extrusion molding of a tubular molding is thereby accomplished which varies in outer configurational dimension and inner configurational dimension in a longitudinal direction.