Abstract: By 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 c

Abstract: A molded product with a variable cross sectional configuration in the longitudinal direction is subjected to extrusion molding by using a die set for extruding a molding with a variable section in a longitudinal direction, the die set comprising a first die 10 and a second die 11, the first die 10 and the second die 11 being relatively movably disposed along the web shaping-holes 16 and 28 and arranged in order in the extruding direction of a molding material such that a first extrusion hole 14 and a second extrusion hole 30 have web shaping-holes 16 and 28 communicated with each other and a flange portion shaping-hole 15 (27) of one of the dies is situated on the side of a flange portion communication hole 29 (17) of the other die, and relatively moving the first die 10 and the second die 11 while extruding the molding material towards the variable section extrusion die set.