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US 4,227,908 AGranted
Shaping glass sheets by drop forming with sag control means
AssigneePPG Industries, Inc.
InventorSamuel L. Seymour
Life of this patent
Estimating the term…
Abstract
Spacer elements affixed to the face of a flat vacuum platen induce a temporary reverse bow in a heat softened glass sheet held on the platen. The bowing is in the opposite direction from that of the final curvature, so that when the glass sheet is subsequently dropped onto a shaping mold the resulting sag in at least one direction is reduced.
Claims18
A method of shaping glass sheets, comprising the steps of:
- heating a glass sheet to approximately its softening point;
- bringing a surface of the glass sheet and a flat perforated plate of a vacuum plate into close proximity to each other with a spacing member interposed between the plate and marginal portions of the glass sheet;
- drawing a vacuum through the perforated plate so as to retain the glass sheet on the platen and to bring said marginal portions of the glass sheet to bear against the spacing means, whereby the vacuum draws remaining portions of the glass sheet closer to the plate than said marginal portions, thereby bowing the glass sheet;
- supporting the platen and the bowed glass sheet carried thereon in an essentially horizontal orientation with the glass sheet under the platen;
- bringing into vertical alignment with and beneath the glass sheet held on the platen a shaping mold having a contour defining the desired contour for the glass sheet;
- and
- releasing the glass sheet from the platen so as to fall onto the shaping mold and conform to the contour defined by the shaping mold.
4 more elements
An apparatus for shaping glass sheets comprising;
- furnace means for heating glass sheets to a softened condition;
- support means adjacent to the furnace means for supporting glass sheets;
- conveyor means for transferring glass sheets from the furnace means to the support means;
- a platen having a flat perforated plate and having an enclosed interior space in communication with a source of vacuum;
- means for transferring the platen into and out of close proximity to the support means so as to lift the glass sheet from the support means by means of vacuum;
- spacing means supported before said flat perforated plate so as to be interposed between the plate and marginal portions of a sheet of glass retained on the platen;
- a shaping mold having upwardly facing shaping surfaces defining the desired curvature and corresponding to the shape of the glass sheets;
- and
- shuttle means for alternately bringing the platen and the shaping mold into and out of superimposed vertically spaced relationship to each other, wherein the shaping mold in the superimposed position is supported at an elevation below the perforated plate so as to receive and shape a glass sheet dropped from the platen.
6 more elements
Dependencies are inferred from the claim text.