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US 4,063,705 AGranted
Vacuum forming mold
OwnerRichard J. Vodrainventor
Life of this patent
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OwnerRichard J. Vodrainventor
Estimating the term…
A mold for vacuum forming plastic sheet and the like and a method of making the mold. A relatively thin mold shell provides a forming surface through which small apertures open to exhaust air to vacuum form a heat-softened plastic sheet. Small manifold conduits behind the forming surface connect the apertures to a source of vacuum. The mold area subtended by the manifold conduits is substantially less than the area of the entire forming surface, thereby substantially limiting the force exerted upon the forming surface by the pressure differential created during vacuum forming of a plastic sheet. The mold is preferably made by electroforming a metallic shell on a pattern, and is apertured in a desired pattern. Filaments are advantageously used to form the apertures during electroforming. A low melting point material is applied to the back of the shell in a manifold pattern to connect the apertures and a metallic layer is electroformed to the back of the shell. The material forming the manifold pattern is then melted and removed.
A mold for vacuum forming, comprising a lamination of metallic layers at least one of which is electroformed, with interconnected narrow and elongated gaps between two laminae and along predetermined paths, said gaps serving as fluid-conducting passages and said lamination having a surface portion defining a forming area that is then relative to the extent of the forming area and centrally unsupported, the lamination being thicker along the predetermined paths than elsewhere by an amount substantially equal to the height of the gaps;
A mold for vacuum forming, comprising an electro-formed lamination of metallic layers with interconnected narrow and elongated gaps between two laminae and along predetermined paths, said gaps serving as fluid-conducting passages and said lamination having a surface portion defining a forming area that is thin relative to the extent of the forming area and centrally unsupported;
Dependencies are inferred from the claim text.