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US 4,123,246 AGranted
Shaping and quenching glass sheets by roll forming using transition quench rolls
AssigneePPG Industries, Inc.
InventorRandall S. Johnson
Life of this patent
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AssigneePPG Industries, Inc.
InventorRandall S. Johnson
Estimating the term…
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.
In apparatus for shaping and tempering glass sheets comprising a furnace, a cooling section spaced from said furnace and a forming section and a quenching section interposed between said furnace and said cooling section, a series of rotating forming rolls longitudinally spaced from one another along a generally arcuate path of approximately constant longitudinal curvature through said forming section and within at least a major portion of said quenching section, wherein the rotating rolls of said series within said quenching section closer to said cooling section are disposed in an upwardly sloped portion of said arcuate path whose upward slope increases to a slope at which a glass sheet would slip when engaged by adjacent rotating rolls disposed along said path, the improvement comprising means supporting said adjacent rotating rolls in said quenching section disposed in said upwardly sloped portion in such relative vertical positions of misalignment with said arcuate path that the maximum upward slope from roll to roll is less than an upward slope at which the glass sheets would slide relative to said adjacent rotating rolls.
In a method of shaping and tempering a series of glass sheets by the roll forming process comprising heating a plurality of glass sheets to a glass deformation temperature and conveying each of said plurality of glass sheets on a series of rotating forming rolls disposed along an arcuate path of substantially constant radius of curvature having a generally descending portion adjacent where the glass sheets are heated to shape said glass sheets to a curvature conforming to said arcuate path, and cooling said shaped glass sheets while conveyed on additional rotating rolls disposed along a continuation of said arcuate path rapidly enough to harden the glass sheet surfaces, the improvement comprising transferring said glass sheets after their surfaces have hardened to rotating rolls disposed along a line having a maximum upward slope from roll to roll less than an upward slope at which the glass sheet would slide relative to said rotating rolls.
In a method of shaping and tempering glass sheets by roll forming in which a continuously moving sheet while heated to at least its deformation temperature successively passes over a plurality of rotating forming rolls extending transversely and longitudinally spaced from one another to define a discontinuous arcuate longitudinal path of movement of substantially constant radius of curvature, said path having an upstream path portion of decreasing downward slope and a downstream path portion of increasing upward slope to form a curved shape of substantially constant radius of curvature correlated with said curved path of movement, conveying said sheet on said rotating forming rolls, thus lowering said sheet in the upstream portion of said path along a downwardly curved portion of said path to develop said curved shape and applying cold tempering medium to chill the surfaces of said sheet having said curved shape while continuing to convey said sheet over said rotating rolls, the improvement comprising transferring said sheet after its chilled surfaces have hardened sufficiently to reduce surface damage due to engagement with misaligned rolls from said rotating rolls disposed along said downstream path portion to rotating rolls misaligned with said arcuate path and aligned at an upward slope less than the slope at which the glass sheets would slide relative to said rotating rolls.
A method of shaping glass sheets to a compound curvature by roll forming and tempering said shaped sheets comprising
Dependencies are inferred from the claim text.