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US 4,229,199 AGranted
Shaping glass sheets by drop forming with differential vacuum release
AssigneePPG Industries, Inc.
InventorSamuel L. Seymour
Life of this patent
Estimating the term…
Abstract
In a drop forming process for shaping glass sheets, wherein a glass sheet is dropped from a flat vacuum platen onto a shaping mold, the final curvature of the glass is controlled by releasing a portion of the glass sheet from the platen prior to releasing the remainder of the glass sheet.
Claims24
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 platen into close proximity to each other;
- drawing a vacuum through the platen so as to retain the glass sheet on the platen;
- supporting the platen and the 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 on a shaping mold having a contour defining the desired contour for the glass sheet;
- releasing the vacuum from a portion of the platen adjacent to a first area of the glass sheet while maintaining vacuum in the remaining portion of the platen adjacent to a second area of the glass sheet whereby a sufficient bending force is created in the glass sheet to impart a curvature thereto;
- 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.
5 more elements
An apparatus for shaping glass sheets comprising:
- a furnace for heating glass sheets to a softened condition;
- a bending station at an exit end of the furnace;
- conveyor means for transferring glass sheets heated in the furnace into the bending station;
- a platen associated with the bending station, having a plurality of enclosed chambers bounded on a common side by a flat, perforated plate, each of the chambers being in communication with a source of vacuum;
- valve means for periodically interrupting the vacuum supply to at least one of said chambers while maintaining vacuum in the remainder of the chambers;
- lift means for bringing the perforated plate of the platen and a heated glass sheet in the bending station into close proximity to each other so that vacuum in the platen may retain the glass sheet thereon, and for bringing the perforated plate and the glass sheet thereon to a generally horizontal orientation with the perforated plate facing downwardly;
- 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.