To solve the problems of a quite deterioration in efficiency of a work such as a burr removing work, and of increased defects of deformation of a final product due to the fact that a rigidity is reduced to such a degree that mere holding of a duct after removing it from a die by a forming worker causes deformation of the product if a wall thickness of the duct is made thin in order to make it lightweight.
This invention relates to a method for manufacturing a duct by means of a blow molding of thermoplastic resin in which after reinforcement agent including thermosetting resin is blown into a cavity of divided molds for the duct, a parison to be formed into the duct is hung down into the divided molds, the divided molds are closed, blow-up operation is performed to adhere the reinforcement agent to the parison, then the prison is removed from the molds together with the reinforcement agent hardened with heat of the parison. Thus, the problems are solved.
MURAMATSU YASUHIDE
OTSUKA YUTO
