Abstract:
A glass sheet quench station ( 16 ) includes first and second quench sections ( 24  and  26 ) that cooperate with a three position shuttle ( 28 ) and a control ( 30 ) to transfer glass sheets through the quench station with partial quenching performed at the first quench station and completion of the quenching at the second quench section. This glass sheet quenching method with two stage quenching shortens the cycle time to provide increased production.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a quench station and a method for quenching formed glass sheets in a manner that can reduce cycle time and thus increase production.  
           [0003]    2. Background Art  
           [0004]    Systems for forming glass sheets by heating and then quenching the glass sheets to provide toughening have cycle times whose shortening can be limited by the length of time required to perform the quenching. The quenching is performed by quenching gas that is directed to opposite surfaces of the formed glass sheet to provide a temperature differential between the surfaces and the glass center. That temperature differential must remain throughout the cooling until reaching ambient temperature or the glass will not be toughened by providing compression of its surfaces and tensioning of its center.  
           [0005]    U.S. Pat. No. 4,361,432 McMaster et al. discloses glass sheet quenching between lower and upper quench heads with the formed glass sheet on an open center ring and, upon completion of the quenching, the downwardly directed quenching gas from the upper quench head is terminated to lift the glass sheet upwardly from the open center ring against the upper quench head to permit the ring to be moved to start another cycle. A delivery ring is moved under the formed glass sheet and the downwardly directed gas is again supplied to deposit the glass sheet on the delivery ring for delivery when the next formed glass sheet is moved to between the lower and upper quench heads for the quenching.  
         SUMMARY OF THE INVENTION  
         [0006]    One object of the present invention is to provide an improved quench station for quenching formed glass sheets.  
           [0007]    In carrying out the above object, the quench station for quenching formed glass sheets in accordance with the invention includes a first quench section having lower and upper quench head assemblies for respectively supplying upwardly and downwardly directed quenching gas to a formed glass sheet therebeween to provide partial quenching of the glass sheet. Such partial quenching is insufficient without further forced cooling in addition to natural convection to prevent the loss of the glass temperature differentials that toughens the glass upon finally cooling to ambient temperature. A second quench section of the quench station has lower and upper quench head assemblies for respectively supplying upwardly and downwardly directed quenching gas to the partially quenched glass sheet upon being received therebetween to complete the quenching of the glass sheet. A shuttle of the quench station is movable in a transfer direction simultaneously with respect to a forming station where the glass sheet is formed, the first quench section and the second quench section to provide glass sheet transfer. The shuttle has three glass positions so as to be capable of simultaneously transferring three glass sheets upon each movement in the transfer direction. Three glass sheets are thus simultaneously moved from the forming station to the first quench section, from the first quench section to the second quench section, and from the second quench section for delivery. A control of the quench station supplies quenching gas to the upper and lower quench sections of the first and second quench sections to force the glass sheets upwardly from the shuttle against the upper quench head assemblies and permit movement of the shuttle in the opposite direction to the transfer direction in preparation from the next cycle.  
           [0008]    The construction of the quench station includes a framework, and the lower and upper quench head assemblies of each quench section each includes a plurality of quench heads through which pressurized gas is delivered. The quench heads of each quench head assembly are adjustable with respect to each other to permit quenching of different shapes of formed glass sheets. The lower and upper quench head assemblies respectively include lower and upper templates mounted on the framework to position the quench heads thereof in the proper position for the glass sheet shape to be quenched. Adjusters of the quench station adjust the locations of the templates on the framework to properly position the quench heads. Clamps secure the templates with respect to the framework, with the clamping being provided after the adjustment provided the adjusters.  
           [0009]    The lower and upper quench head assemblies respectively include lower and upper linkages for connecting their quench heads. Lower and upper quench head actuators respectively extend between the framework and the lower and upper quench head assemblies to provide adjusting movement of the quench heads under the control of the linkages in preparation for positioning the quench head assemblies by the lower and upper templates.  
           [0010]    Each of the upper quench head assemblies includes thermally insulative stops against which the glass sheets are forced upwardly by the upwardly directed quenching gases during the cyclical operation of the quench station.  
           [0011]    Another object of the present invention is to provide an improved method for quenching formed glass sheets.  
           [0012]    In carrying out the immediately preceding object, the method for quenching formed glass sheets in accordance with the invention is performed by moving a first formed glass sheet on a shuttle from a forming station to a first quench section having lower and upper quench head assemblies for respectively supplying upwardly and downwardly directed quenching gas to provide partial quenching thereof which is insufficient without further forced cooling in addition to natural convection to prevent loss of the glass temperature differential that toughens the glass upon finally cooling to ambient temperature. Simultaneously with the movement of the first formed glass sheet, a second partially quenched formed glass sheet is moved on the shuttle from the first quench section to a second quench section having lower and upper quench head assemblies for respectively supplying upwardly and downwardly directed quenching gas to the partially quenched glass sheet upon being received therebetween to complete the quenching of the second glass sheet. Simultaneously with the movement of the first and second glass sheets a third fully quenched glass sheet is moved from the second quench station for a final cooling to ambient temperature. The flow of the quenching gas from the lower and upper quench head assemblies of the first and second quench sections is controlled to move the formed glass sheet upwardly from the shuttle after movement thereto on the shuttle and thereby permits reverse movement of the shuttle in preparation for another cycle. Subsequently the flow of the quenching gas from the lower and upper quench head assemblies of the first and second is controlled to move the formed glass sheets downwardly onto the shuttle to permit another cycle of transferring three formed glass sheets from the forming station to the first quench section, from the first quench section to the second quench section, and from the second quench section for final cooling.  
           [0013]    In performing the quenching method, the lower and upper quench head assemblies are respectively positioned by lower and upper templates, and the lower and upper templates are adjusted with respect to a framework of the quench sections and are clamped with respect to the framework to position the lower and upper quench head assemblies. Furthermore, the quench heads of the lower and upper quench head assemblies are respectively connected by lower and upper linkages and are moved by associated actuators for positioning in preparation for use.  
           [0014]    During the quenching, the glass sheets are forced upwardly against thermally insulative stops of the upper quench head assemblies.  
           [0015]    The objects, features and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment when taken in connection with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a schematic side elevational view of a glass sheet processing system including a quench station constructed in accordance with the invention to perform the quenching method of the invention.  
         [0017]    [0017]FIG. 2 is a cross sectional view taken through the quench station along the direction of line  2 - 2  in FIG. 1 to illustrate lower and upper quench head assemblies that respectively provide upwardly and downwardly directed quenching gas to quench a formed glass sheet therebetween.  
         [0018]    [0018]FIG. 3 is an enlarged view of a portion of FIG. 2 to further illustrate the lower and upper quench head assemblies and lower and upper templates that provide positioning of quench heads of each quench head assembly.  
         [0019]    [0019]FIG. 4 is a sectional view taken through the quench station generally in the same direction as FIG. 2 but at a different location to illustrate lower and upper linkages that provide connection between the quench heads of the lower and upper quench head assemblies.  
         [0020]    [0020]FIG. 5 is a sectional view taken in the same direction as FIG. 4 but at a different location to illustrate the manner in which actuators moves the quench heads of the lower and upper quench head assemblies in preparation for positioning thereof by the lower and upper templates illustrated in FIGS. 2 and 3.  
         [0021]    [0021]FIG. 6 is a view taken along the direction of line  6 - 6  in FIG. 3 to illustrate the manner in which the upper template is positioned by an adjuster and clamp to a framework of the quench station.  
         [0022]    [0022]FIG. 7 is a view taken along the direction of line  7 - 7  in FIG. 3 to illustrate the manner in which the lower template is positioned by an adjuster and secured by a clamp to the quench station framework.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    With reference to FIG. 1, a glass sheet forming and quenching system generally indicated by  10  includes a furnace  12  for heating glass sheets, a forming station  14  for forming the heated glass sheets, and a quench station  16  that is constructed in accordance with the invention to provide the quenching method thereof as is hereinafter more fully described. The construction of the quench station  16  and its method of operation will be described in an integrated manner to facilitate an understanding of all aspects of the invention.  
         [0024]    With continuing reference to FIG. 1, the furnace  12  of the system includes a conveyor  18  on which glass sheets G are heated within a heating chamber of the furnace to a sufficiently high temperature to permit forming and quenching of the glass. After the heating, the heated glass sheets G are transferred or conveyed in any suitable manner to the forming station  14  where forming apparatus  20  forms each heated glass sheet from a flat shape to a curved shape. After the forming, the heated glass sheet is supported as illustrated by an upper vacuum mold  22  in preparation for being transferred to the quench station  16  which, as mentioned above, is constructed in accordance with the present invention.  
         [0025]    The quench station  16  of the invention as illustrated in FIG. 1 includes first and second quench sections  24  and  26 , a shuttle  28  that simultaneously provides movement of three formed sheets G 1 , G 2 , and G 3  through the quench station as is hereinafter more fully described. In addition, the quench station also includes a control  30  that supplies quenching gas in a controlled manner which during cyclical operation moves the glass sheets upwardly from and subsequently downwardly back onto the shuttle  28  upon passage through the quench station. It should be noted that the formed glass sheets normally will have curvature in a transverse direction to the direction of conveyance through the quench station  26  and may also have curvature along the direction of conveyance as illustrated.  
         [0026]    As illustrated by FIGS. 1 and 2, the first quench section  24  has lower and upper quench head assemblies  32  and  34  for respectively supplying upwardly and downwardly directed quench gas to a formed glass sheet therebetween to provide partial quenching of the formed glass sheet. The quenching provided by the first quench section  24  is insufficient without further forced cooling in addition to natural convention to prevent loss of the glass temperature differential that toughens the glass upon final cooling to ambient temperature, either by heat strengthening or more rapid cooling that provides tempering. The second quench section  26  of the quench station also has lower and upper quench head assemblies  32  and  34  for respectively supplying upwardly and downwardly directed quenching gas to the partially quenched glass sheet upon being received therebetween during the shuttle transfer cycle described below. This quenching in the second quench station  26  completes the quenching of the glass sheet to provide heat strengthening or tempering as required by the particular manufacturing job being processed. Downstream to the right of the second quench section  26 , the quench station includes an after-cooling section  36  having an upper stop  38  against which a quenched glass sheet is supported during the transfer cycle in preparation for being transferred to an unshown after-cooling conveyor and ultimate delivery from the system.  
         [0027]    The shuttle  28  illustrated in FIG. 1 is movable along a transfer direction that corresponds with the direction conveyance C toward the right through the system and is moved by an actuator  40  so as to be simultaneously moved with respect to the forming station  14  where each glass sheet is formed, the first quench section  24 , and the second quench section  26  as well as the after-cooling section  36 . The shuttle  28  has three positions each of which includes an associated open ring  42 ,  44  and  46  for respectively supporting and transferring three glass sheets during each movement toward the right. More specifically, the shuttle  28  simultaneously moves the one glass sheet G 1  from the forming station  14  to the first quench section  24  as shown, the second glass sheet G 2  from the first quench section  24  to the second quench section  26  as shown, and the third glass sheet G 3  from the second quench section  26  to the after-cooling section  36  for transfer to the unshown after-cooling conveyor and ultimate delivery as previously mentioned.  
         [0028]    As illustrated further in FIG. 1, the gas quench control  30  includes a source  48  of pressurized quenching gas that is delivered to the quench station through a main supply conduit  50 . A valve controller  52  controls valves  54  and  56  that respectively control flow through delivery conduits  58  and  60  to the lower and upper quench head assemblies  32  and  34  of the first quench section  24 . Valve controller  52  also controls valves  62  and  64  that control the flow of quenching gas through conduits  66  and  68  that supply the lower and upper quench head assemblies  32  and  34  of the second quench station  26 . In addition, the valve controller  52  controls a valve  70  that controls the flow of quenching gas  72  to a lower blowup plenum  74  that supplies upwardly directed quench gas at the after-cooling station  36 .  
         [0029]    Each cycle of operation of the shuttle  28  illustrated in FIG. 1 is performed by moving the shuttle from the left toward the right to the position illustrated to transfer three glass sheets, one glass sheet G 1  from the forming station  14  to the first quench section  24 , the second glass sheet G 2  from the first quench section  24  to the second quench section  26 , and the third glass sheet G 3  from the second quench section  26  to the after-cooling section  36 . With the shuttle positioned as shown in FIG. 1, the quenching gas is supplied under the operation of control  30  to the first and second formed glass sheets G 1  and G 2  for a sufficient time to provide the partial quenching of the first glass sheet G 1  and to complete the quenching of the second glass sheet G 2 . The time involved for such quenching will depend upon the glass thickness but will normally be about 1½ to 2 seconds. The control  30  then provides a change in the force applied to the glass sheets to provide lifting thereof upwardly off of the associated shuttle rings  42 ,  44  and  46 . Thus, the glass sheet G 1  is moved upwardly against the upper quench head assembly  34  of the first quench section  24 , the second glass sheet G 2  is moved upwardly against the upper quench head assembly  34  of the second quench section  26 , and the third glass sheet G 3  is moved upwardly against the stop  38  of the after-cooling section  36 . The quenching proceeds at this time with the lower quench head assemblies  32  of both the first and second quench sections  24  and  26  continuing to supply upwardly directed quenching gas and with the upper quench head assemblies  34  continuing to supply downwardly directed quenching gas. Simultaneously, the movement of the shuttle  28  back toward the left permits commencement of another cycle as the glass sheets progress through the quench station from the left toward the right with three being moved during each shuttle movement toward the right. Prior to the commencement of each cycle, the quenching gas supplied to the first and second quench sections  24  and  26  is changed by the control  30  to release the formed glass sheets from their associated upper quench head assemblies  34  to allow the glass sheet thereof to respectively drop downwardly onto the shuttle rings  44  and  46  in preparation for respective movement from the first quench section  24  to the second quench section  26  and for movement from the second quench section  26  to the after-cooling section  36 . The change in the gas flows to lift the glass sheets can be done by: (1) increasing the upward gas flow; (2) decreasing the downward gas flow; or (3) both increasing the upward gas flow and decreasing the downward gas flow.  
         [0030]    When the glass sheets are forced upwardly against the upper quench head assemblies  34  in both the first and second quench section  24  and  26  shown in FIG. 1, the greater supply of upwardly directed quenching gas relative to the amount of downwardly directed quenching gas is offset by the fact that the glass sheets are positioned closer to the upper quench head assemblies  34  so that the cooling provided is more uniform from both the lower and upper sides.  
         [0031]    As illustrated in FIGS. 1 and 2, the lower and upper blast head assemblies  32  and  34  each include a plurality of quench heads  76  and  78 , respectively, through which quenching gas is supplied upwardly and downwardly through openings in the opposed faces of the quench heads. Furthermore, as shown in FIG. 1, the upstream ends of the lower and upper quench heads  76  and  78  are respectively connected by lower and upper linkages  80  and  82  and are positioned by lower and upper templates  84  and  86 . Likewise, the downstream ends of the lower and upper quench heads  76  and  78  of the second quench section  26  are also respectively connected by lower and upper linkages  80  and  82  and are positioned by lower and upper templates  84  and  86 . Furthermore, while the lower and upper quench heads  76  and  78  of the lower and upper quench head assemblies  32  and  34  of the first and second quench section  24  and  26  are fluidly isolated from each other, their respective downstream and upstream ends have mechanical lower and upper connectors  88  and  90  so as to be movable and positioned with each other in association with the lower and upper linkages  80  and  82  and the lower and upper templates  84  and  86 .  
         [0032]    As shown in FIGS.  2 - 5 , the quench station includes a framework  92  including vertical posts  94  and horizontal beams  96  on which the lower and upper quench head assemblies  32  and  34  are mounted. Both the lower and upper linkages  80  and  82  of the lower and upper quench head assemblies have a construction best illustrated in FIG. 4 by the lower linkage which includes lower and upper link rows  98  and  99  that each include links  100  having pivotal connections  101  to the associated quench heads and to the adjacent links to provide a saw tooth shape that controls the angular positioning of the quench heads with respect to each other so the lower and upper quench heads oppose each other. The quench heads of the lower and upper quench head assemblies  32  and  34  are thus adjustable with respect to each other to permit quenching of different shapes of formed glass sheets.  
         [0033]    As shown in FIG. 3, the lower and upper templates  84  and  86  have upwardly facing positioning notches  102  and  104  that receive lower and upper positioners  106  and  108  on the adjacent ends of the lower and upper quench heads  76  and  78  to provide proper positioning of the quench heads with the associated linkages providing the proper angular location of the lower and upper quench heads with respect to each other.  
         [0034]    As illustrated in FIG. 2, the quenching gas supply ducts  50   a  and  50   b  supply pressurized quenching gas to flexible lower and upper conduits  58  and  60  that respectively supply quenching gas to the lower and upper quench heads  76  and  78  of the lower and upper quench head assemblies  32  and  34 .  
         [0035]    The lower and upper linkages  80  and  82  of the lower and upper quench head assemblies  32  and  34  as mentioned above ensure that the opposed faces of the lower and upper quench heads  76  and  78  are aligned with each other in order to provide uniform distribution of quenching gas to the quenched glass sheet G therebetween. Furthermore, as illustrated in FIGS. 3, 6 and  7 , lower and upper adjusters  110  and  112  respectively associated with the lower and upper templates  84  and  86  provide the proper positioning of the templates on the framework  92  in order to provide the proper positioning of the lower and upper quench heads  76  and  78  in association with the angular positioning provided by the lower and upper linkages. Each adjuster  110  and  112  as shown in FIGS. 6 and 7 includes a threaded adjusting member  114  that is received by a threaded member  116  on the associated template and has a lower end engaged with a support lug  118  on the framework  92  such that threading of the adjusting member provides upward and downward movement of the template to the proper location. Upon such proper positioning, a lock nut  120  on the adjusting member  114  is threaded against the template mounted member  116  to secure the adjusted position.  
         [0036]    As also illustrated in FIGS. 3, 6 and  7 , lower and upper clamps  122  and  124  respectively associated with the lower and upper templates  84  and  86  provide clamping of the templates to the framework  92  after the adjustment provided by the lower and upper adjusters  110  and  112  as described above. As illustrated in FIGS. 6 and 7, the lower and upper clamps  122  and  124  include clamp members  126  that are operated by clamp actuators  128  in any conventional manner to clamp the associated template against the framework  92  and prevent any movement thereof after the adjustment of the templates to the proper position. Clamp connectors  130  of each clamp extend from the clamp member  126  to the clamp actuator  128  and are received within downwardly opening notches  132  (FIG. 3) in the lower side of the associated template so as to permit the upward and downward adjusting movement as necessary until the template is in the proper position for the clamping.  
         [0037]    As best illustrated in FIG. 4, the lower and upper quench head assemblies include lower and upper actuators  134  and  136  that extend between the framework  92  and the lower and upper quench head assemblies  32  and  34 . More specifically, each of the lower and upper quench head assemblies  32  and  34  has a center quench head  76 ,  78  that is fixedly positioned while the other quench heads are movable under the control of the lower and upper linkages previously described.  
         [0038]    The movement of the quench head assemblies for positioning by the templates as previously described prior to adjustment by the adjusters that were also previously described is initially provided by the lower and upper actuators  134  and  136 . The lower actuators  134  have lower ends that are mounted on lower horizontal beams  96  and extend upwardly for connection to the lower quench head assembly  32  with some of the actuators having connections through links  138  and others having pivotal connections  140  connected directly to the associated lower quench heads  78 . The lower actuators  134  are extendible to move the lower quench heads upwardly as required with the associated lower linkage  80  providing control of the angular position of the quench heads as they are moved.  
         [0039]    The upper actuators  136  illustrated in FIGS. 4 and 5 are mounted on upper horizontal beams  96  of the framework  92  and have connections  142  extending downwardly to a pair of links  144  that are connected to an adjacent pair of the upper quench heads  78 . These upper actuators  136  move the upper quench heads  78  under the control of these upper linkages which provide the proper angular positioning so as to oppose the lower quench heads.  
         [0040]    As best illustrated in FIG. 5, the upper quench head assembly  34  includes thermally insulative stops  146  against which the glass sheets are forced upwardly by the quenching gas during the transferring operation as previously described. These thermally insulative stops  46  position the glass sheet and have sufficiently low thermal conductivity so as not to provide excessive conductive cooling thereof that would disrupt the uniformity in the glass cooling.  
         [0041]    As shown in FIGS. 2 and 4, the quench station framework  92  includes an upper frame  148  that supports each upper quench head assembly  34  and has a motor driven ball screw mechanism  150  for lifting the upper frame and the upper quench head assemblies to allow broken glass removal as well as maintenance and repair.  
         [0042]    Another system incorporating the quench station, a roll bending station that can be used to provide the glass sheet forming, and a press station that can be used to provide the glass sheet forming are respectively disclosed in U.S. patent applications: (Docket GLT 1773 PUS); (Docket GLT 1774 PUS); and (Docket GLT 1775 PUS), which are all being filed concurrently herewith and the entire disclosures of which are hereby incorporated by reference.  
         [0043]    While the preferred embodiment of the invention has been described, those familiar with the art to which the invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.