Vacuum holder system and method for use in bending glass

摘要

A system (10) and method disclosed for use in bending glass incorporate a vacuum holder (12) having a surface (28) with spaced openings (32) in which a vacuum is drawn to support a heated sheet of glass (G) and in which pressurized gas is subsequently supplied to force the glass sheet away from the holder surface. In one embodiment, operation of a control damper (24) initially communicates a vacuum blower (20) with the holder and subsequently communicates a positive pressure air blower (22) therewith to first draw the vacuum and then supply the pressurized air to the openings in the surface which is disclosed facing downwardly. During an intermediate step, the damper is positioned so that a reduced vacuum is drawn to prevent deformation of the heated glass sheet at the spaced openings in the holder surface. In an alternative embodiment, a gas jet pump (90) is used to produce the positive and vacuum pressures used in the practice of the invention. The gas jet pump produces the desired pressure condition by developing a large quantity, secondary flow of gas in response to a primary flow of gas. The direction of the secondary flow can be selectively controlled to develop either a positive pressure or vacuum pressure.