Apparatus for quenching formed glass sheets

Abstract

Apparatus ( 42 ) for quenching a formed glass sheet with three steps of gas flow pressures in a manner that reduces cycle time without excessive temporary surface tension that can cause excessive breakage. A control ( 26 ) provides the quenching in the three step manner with initial pressures for .5 to 1.3 seconds, increased pressures of at least 25% greater than the initial pressures for .5 to 4 seconds, and final quenching with decreased cooling power that is less than the cooling power of the initial pressures.

What is claimed is: 
     
         1 . Apparatus for quenching glass sheets comprising:
 a quench system including a quench having lower and upper quench heads that are operable to supply upward and downward gas flows;   a quench ring for positioning a heated and formed glass sheet between the quench heads for quenching;   a control for operating the quench to initially supply through the lower and upper quench heads upward and downward gas flows at initial pressures for about 0.5 to 1.3 seconds to quench the formed glass sheet;   the control then increasing the upward and downward gas flow pressures through the lower and upper quench heads to at least 25% greater than the initial pressures for 0.5 to 4 seconds; and   the control thereafter operating the quench system to continue to supply upward and downward gas flows to the formed glass sheet with decreased cooling power that is less than the cooling power of the initial pressure quenching to eventually provide a tempered and formed glass sheet upon cooling throughout to ambient temperature.   
     
     
         2 . Apparatus for quenching glass sheets as in  claim 1  wherein the quench includes quench heads that are movable between an open position where the formed glass sheet is transferred into and out of the quench and a closed position in which the initial pressure and increased pressure quenching are performed. 
     
     
         3 . Apparatus for quenching glass sheets as in  claim 2  wherein the quench ring transfers the heated and formed glass sheet into the open quench and supports the formed glass sheet during the initial pressure and increased pressure quenching. 
     
     
         4 . Apparatus for quenching glass sheets as in  claim 3  further including an aftercooler to which the quench ring moves the formed glass sheet from the open quench for at least some of the decreased cooling power quenching. 
     
     
         5 . Apparatus for quenching glass sheets as in  claim 3  further including an aftercooler and a transfer device that receives the formed glass sheet from the quench ring to provide transfer thereof from the open quench to the aftercooler for at least some of the decreased cooling power quenching. 
     
     
         6 . Apparatus for quenching glass sheets comprising:
 a quench system including a quench having lower and upper quench heads that are movable between open and closed positions and operable to supply upward and downward gas flows;   a quench ring for moving a heated and formed glass sheet to between the open quench heads which are then closed for quenching;   a control for operating the quench to initially supply through the closed lower and upper quench heads upward and downward gas flows for about 0.5 to 1.3 seconds at conventional quench pressures to quench the formed glass sheet;   the control then increasing the upward and downward gas flow pressures through the lower and upper quench heads to least 25% greater than the initial pressures for 0.5 to 4 seconds;   the control thereafter operating the quench system to continue to supply upward and downward gas flows to the formed glass sheet with decreased cooling power that is less than the cooling power provided by the quench at minimum conventional quench pressures to eventually provide a tempered and formed glass sheet upon cooling throughout to ambient temperature, and the decreased cooling power quenching initially being provided by the upper and lower quench heads which are opened by the control; and   an aftercooler to which the control moves the formed glass sheet for further decreased cooling power quenching.