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Abstract

[Objects] In a method for forming a duct used as, e.g., an air duct for an automobile engine, and provided with a corrugated section as an undercut part in a part of the longitudinal direction of the duct, an elastomeric duct is formed with ensuring easy removal of a duct molded by injection from a core die even when the duct is made of a resin poor in elasticity. [Means to Solve the Problems] A method for forming an elastomeric duct having a corrugated section in a longitudinal direction thereof as a part of the duct by injection molding, which comprises injecting an elastomer material into a cavity formed with a cavity die for forming an external surface of the duct, and a core die for forming an internal surface of the duct, wherein the core die is a splittable core die which is axially splittable into two parts, one is a core die A for forming a duct area at least containing the corrugated section, and the other is a core die B for forming a duct area free from the corrugated section, and removing the duct area containing the corrugated section from the core die A with expanding at least the corrugated section in the radius direction by air injection after opening the cavity die.

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First Claim