Abstract: A deformable vacuum holder used in the shaping of sheets of glass or other deformable materials is provided with a plurality of longitudinally extending helical coil springs that enhance the durability of the deformable vacuum holder. When the outer diameter of the springs approximates the thickness of a chamber comprising said holder, the springs improve the resistance of the holder to collapse in response to the application of vacuum to said holder.
Abstract: In the art of shaping sheets of glass and other deformable materials comprising engagement of said sheets while hot by a vacuum holder in a relatively hot atmosphere and removing the holder into a cooler atmosphere to cool the holder between successive shaping cycles, production of shaped sheets was limited by the time necessary for the holder to cool during its exposure to said cooler atmosphere to a temperature suitable for beginning a subsequent sheet shaping cycle. The present invention lessens this necessary time by drawing cold air by suction from said cooler atmosphere between successive shaping cycles, thereby increasing the maximum production rate possible.
Abstract: Treating a plastic sheet blank, preferably an acrylic resin sheet, along its edge surface by applying a groove of non-uniform depth to its edge surface along a side of the blank having a length to blank thickness ratio that exceeds a critical ratio for the given blank thickness to improve the conformance of the outline of the compression stretched sheet to one similar to the outline of the thick blank prior to its compression stretching and so stretch the blank more uniformly along its orthogonal axes during the compression stretching of said blank to form said sheet.