Patent ID: 6520759
Filing Date: 2003-02-18
Classification: B29C

Abstract:
A manufacturing device of a foamed thermoplastic resin sheet, comprising:an extruder for melting and kneading a thermoplastic resin and a foaming agent to form a melted/kneaded mixture, and extruding the melted/kneaded mixture; a die provided at a front end of said extruder, for forming the melted/kneaded mixture into a sheet form foamy thermoplastic resin material; a vacuum chamber in which the foamy thermoplastic resin material extruded through said die expands under a reduced pressure; a facing-wall section composed of a pair of walls of said vacuum chamber which face each other in a thickness direction of the foamy thermoplastic resin material, at least one of the walls being a movable wall that is movable in directions in which said walls approach and separate each other, and is movable while staying in a parallel state with the other wall of said pair of walls, and wherein at least one of said pair of walls has vacuum ports with a diameter of 20 mm or smaller; a sealing member provided at least on said movable wall in said facing-wall section, at an outlet of said vacuum chamber, so as to seal a space between said wall and a foamed thermoplastic resin sheet coming out of said vacuum chamber, the foamed thermoplastic resin sheet being obtained as a result of expansion of the foamy thermoplastic resin material under a reduced pressure; and driving means for driving said movable wall so as to control a space in said facing-wall section, depending on a thickness of the sheet form foamy thermoplastic resin material changed by the expansion caused by the reduced pressure.