Method and apparatus for injection foam molding

US Patènt # 6863850

Invèntors:	Brown; Bari William (Ann Arbor, MI); Byma; George Bernard (Clarkston, MI)
Assignee:	Lear Corporation (Southfield, MI)
Appl. No.:	271468
Filed:	October 16, 2002

ABSTRACT

A method of manufacturing a foamed plastic article includes disposing a release film on a mold surface of a mold cavity. At least a portion of a bushing is inserted through the release film to form an aperture in the release film. The bushing defines an inlet for foamable material. The mold cavity is then sealed. The foamable material is then injected into the mold cavity through the inlet, wherein the foamable material is conformed to the shape of the mold cavity.

TECHNICAL FIELD

This invèntion relates to the injection molding of foamed plastic articles and, more particularly, to an improved apparatus and method of injection molding foamed plastic articles.

BACKGROUND OF THE INVÈNTION

A known method of manufacturing foamed plastic articles is known as a pour-in-place method. In such a method, a film can be placed in the lower mold part of a mold assembly. A vacuum is applied at the molding surface of the lower mold part to draw the film to the molding surface. A foamable material, such as a foamable polyurethane liquid, is poured into the lower mold part on top of the film. A cooperating upper mold part, having a molding surface which defines a desired shape, is moved into cooperating engagement with the lower mold part. If desired, a component such as carpet, is placed on the foamable material. The foamable material is foamed and cured under heat and pressure, resulting in a relatively rigid substrate of foamed material with the component attached thereto. The resulting article has an exterior surface, such as carpet, backed by a foam layer. However, application of the film can add undesirable additional time to the manufacturing method.

Another known method of manufacturing foamed plastic article is known as injection molding. In a typical injection molding process, a plastic material, such as a foamable material, is introduced into the cavity of a closed hollow mold. Film is typically not used in such an injection molding process, and frequent cleaning of the mold surfaces can be required. The foamed plastic articles formed therein can also adhere to the mold surface, and the removal of such articles from the mold can add undesirable time to the manufacturing process. It would therefore be desirable to provide an improved method of manufacturing foamed plastic articles.