The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 23, 1977
Filed:
Jul. 01, 1976
Thomas J Reese, Sarver, PA (US);
Melvin W Tobin, New Kensington, PA (US);
James R Mortimer, Natrona Heights, PA (US);
PPG Industries, Inc., Pittsburgh, PA (US);
Abstract
Shaping glass sheets of soda-lime-silica compositions by gravity sagging into complicated shapes having a portion of convex curvature and another portion of concave curvature requires a continuous shaping surface onto which a supported glass sheet is heated and sags. The present invention provides a method of bending soda-lime-silica glass sheets onto curved molds of a complicated curvature comprising a previously shaped sheet of a glassy composition having a heat capacity approximating that of the soda-lime-silica composition and a lower coefficient of thermal expansion and a higher deformation temperature than those of the sode-lime-silica composition of the glass sheet to be bent. The layer of glassy composition which provides the mold shaping surface is in turn supported on a metal frame of outline configuration conforming in elevation and outline to the shape of the layer of the special glassy composition, and preferably has a minimum thickness at least equal to the glass sheet to be shaped to insure that when the composite mold comprising the shaped outline metal frame and the superimposed shaped layer supporting a glass sheet to be shaped is heated to the deformation temperature of the glass sheet, the layer retains its shape sufficiently to be used as part of the composite mold in subsequent bending operations. A layer of knit fiber glass composition is held in stretched relation over the upper shaping surface of the layer of special glassy composition to reduce the possibility of surface damage to the shaped glass sheet. Glass sheets shaped on such composite molds by gravity sagging conform closely to the desired complicated shape and also have a desired stress pattern in the marginal edge portion.