Shaping and quenching glass sheets by roll forming using transition

Abstract

This invention relates to shaping and quenching glass sheets by roll forming to either simple or compound curvatures comprising a longitudinal component of curvature about an axis of bending transverse to a path of movement by a controlled, repeatable program of roll forming without causing the glass sheets to stop their forward movement during their shaping. A series of glass sheets are heated and then rapidly cooled while conveyed along a path defined by a conveyor system comprising longitudinally spaced rotating rolls. The path includes a longitudinally curved portion that imparts a longitudinal component of curvature to the glass sheets after the latter are softened by heat. In this invention, shaped solid members such as successive rotating shaping rolls of predetermined contour of a uniform cylindrical or curved configuration engage a heat-softened glass sheet along an arcuate longitudinal path of substantially constant radius of curvature along forming and quenching conveyors of said conveyor system to impart the desired longitudinal component of curvature to the glass and to convey the shaped glass past cool blasts that harden the glass surfaces. The arcuate path is arranged in such a manner that its upward slope at its downstream end is limited to one at which glass sheets move forward toward the cooling conveyor without slipping. A set of at least three special quench rolls forms an upwardly sloped transition conveyor section of constant maximum slope that replaces the downstream portion of the arcuate path where the upward slope would increase to a slope where slippage would take place. The special transition quench rolls are located downstream of the location where blasts of tempering fluid applied at the quenching section have hardened the major glass sheet surfaces sufficiently to avoid their distortion by engagement with the rotating, special transition quench rolls.