Tubular, ported air duct and method for manufacturing the same

Abstract

A ported tubular air duct and a method for manufacturing a side-ported tubular air duct. The air duct has a side port located substantially ninety degrees (90.degree.) to the part line of a mold in which the air duct is manufactured. The mold has two portions which are separated when the mold is opened to permit the positioning a preheated polypropylene tubular port insert member into an opening in one of the mold portions. A parison of rubber modified polypropylene is injected into the mold between the portions at approximately 410.degree. F., and the mold is closed to seal the ends of the parison. The interior of the parison is pressurized to a level in the range of approximately 90 to 100 psi to force the parison outward against the inner sides of the mold cavity and against one end of the port member. At this juncture, the parison has a thickness in the range of 0.060 to 0.090 inches. The parison expands into the opening of the tubular port insert member and is burst by the pressure in the parison such that the parison material flows along the interior of the tubular port insert member and merges therewith. The pressurizing medium, preferably air, is allowed to flow through the port and out of the mold for approximately 10 seconds. A mandrel is then urged into the tubular port insert member so that the system again be fully pressurized. The molded air duct remains in the mold until cooled. The pressure is relieved, the mandrel is withdrawn and the part is removed from the mold.

Dependencies are inferred from the claim text.