Patent ID: 8210841

Claim:
A vacuum-induced injection molding apparatus comprising: a tool surface having an injection port extending therethrough; a flexible film extending over a preform and sealingly coupled to the tool surface, wherein the flexible film comprises an outer surface and an inner surface such that the flexible film inner surface and the tool surface define a first volume; a rigid vacuum chamber having a periphery sealingly coupled to a first portion of the outer surface of the flexible film, the rigid vacuum chamber defining a second volume between an interior of the vacuum chamber and the outer surface of the first portion of the flexible film within the periphery of the vacuum chamber; at least one stiffening bar separate from the periphery of the rigid vacuum chamber, the at least one stiffening bar located outside the first volume and extending between the tool surface and an interface with the vacuum chamber, the interface between the stiffening bar and the vacuum chamber configured to permit the stiffening bar to receive at least a portion of a reaction force transmitted by the vacuum chamber when the second volume contains a relative vacuum; and a vacuum port in fluid communication with the second volume.