Vacuum forming apparatus

Claim 1

A vacuum forming mold for use in a vacuum forming operation in which a heated and softened plastic sheet secured in place is shaped which comprises a first shaped mold plate including an exterior surface against which said secured plastic sheet is disposed and an oppositely directed interior surface, a second mold plate disposed in juxtaposed spaced relation to at least a shaped portion of said interior surface of said first shaped mold plate forming an enclosed hollow space therebetween, said second mold plate having at least one opening, a vacuum source, a connecting pipe extending between said vacuum source and said at least one opening in said second mold plate so that a vacuum can be drawn through the enclosed hollow space, a plurality of openings provided in the first mold plate so that the vacuum established in the enclosed hollow space can draw said secured plastic sheet against the exterior surface of said first shaped mold plate, reinforcing members located within the enclosed hollow space extending between the interior surface of said first mold plate and the facing surface of said second mold plate for preventing the deformation of said first and second mold plates when a vacuum is drawn through the enclosed hollow space, said reinforcing members subdividing the enclosed hollow space into a plurality of subspaces and said reinforcing members having openings therethrough intercommunicating the subspaces, and means for moving said exterior surface of said first mold plate against said secured plastic sheet wherein said means for moving said exterior surface of said first mold plate includes a bed member, with an opening provided therein, so as to form an inner space disposed between said bed member and said second mold plate, such that said inner space is communicated to atmosphere through said opening provided in said bed member and wherein said connecting pipe extends through said opening and is partially disposed within said inner space.