Abstract
A device and a method for bending and cooling sheets of glass including bending the glass by gravity on a gravity support during which the glass rests on the gravity support in the peripheral zone constituted of the 50 mm from the edge of its first principal face, then separating the glass from the gravity support when the glass is at more than 560° C., then cooling the glass during which its first principal face is free of any contact in its peripheral zone, between a temperature termed the upper homogeneous temperature, of at least 560° C., and a temperature termed the lower homogeneous temperature, of at most 500° C., termed the critical temperature range, the zone of the first principal face at a distance greater than 200 mm from the edge being at a temperature at least equal to that of the peripheral zone at the moment when the peripheral zone reaches the upper homogeneous temperature.
Claims
1. A method of bending and of cooling a sheet of glass or a stack of sheets of glass, comprising a first principal face and a second principal face, said method comprising bending the glass by gravity on a gravity support during which the glass rests on the gravity support in a peripheral zone of the first principal face, said peripheral zone being constituted of 50 mm from an edge of the first principal face, then separating the glass from the gravity support, then cooling the glass during which the first principal face is free of any contact in the peripheral zone, in a critical temperature range that is between an upper homogeneous temperature, of at least 560° C., and a lower homogeneous temperature, of at most 500° C., a zone of the first principal face at a distance greater than 200 mm from the edge being at a temperature at least equal to that of the peripheral zone at the moment when the peripheral zone reaches the upper homogeneous temperature.
2. The method as claimed in claim 1, wherein the upper homogeneous temperature is at least 575° C.
3. The method as claimed in claim 2, wherein the lower homogeneous temperature is at most 490° C.
4. The method as claimed in claim 1, wherein during cooling of the glass in the critical temperature range the first principal face of the glass is free of any contact in the 60 mm from the edge.
5. The method as claimed in claim 1, wherein before reaching the upper homogeneous temperature the first principal face is free of any contact for a time that corresponds to a temperature homogenization time of at least 5 seconds.
6. The method as claimed in claim 5, wherein during the temperature homogenization time the glass is held by the second principal face against an upper forming mold provided with suction, the suction producing the force holding the glass against the forming mold.
7. The method as claimed in claim 1, wherein at the moment of separation a zone of the first principal face farther from 50 mm from the edge of the glass is at a temperature higher than that of the peripheral zone.
8. The method as claimed in claim 1, wherein at the moment of reaching the upper homogeneous temperature a zone of the first principal face farther than 50 mm from the edge of the glass is at a temperature at least equal to that of the peripheral zone.
9. The method as claimed in claim 1, wherein the peripheral zone of the first principal face is homogeneous in temperature on any line of intersection of a section perpendicular to the edge of the glass between the upper homogeneous temperature and the lower homogeneous temperature.
10. The method as claimed in claim 1, wherein the glass is supported in at least a part of the critical temperature range by at least one specific support without contact with the peripheral zone of the first principal face.
11. The method as claimed in claim 10, wherein the specific support comprises a plurality of contact zones coming into contact with the first principal face of the glass exclusively at least 50 mm from the edge of the glass.
12. The method as claimed in claim 10, wherein the specific support comprises a plurality of contact zones coming into contact with the first principal face of the glass exclusively at most 200 mm from the edge of the glass.
13. The method as claimed in claim 10, wherein the specific support comprises an inclined track supporting the glass by the lower border of its edge surface.
14. The method as claimed in claim 1, wherein the glass is held in at least a part of the critical temperature range by its second principal face by at least one upper forming mold provided with suction.
15. The method as claimed in claim 10, wherein throughout the critical temperature range the glass is either supported by at least one specific support or held by the second principal face by at least one upper forming mold provided with suction.
16. The method as claimed in claim 1, wherein the gravity support carrying the glass is positioned under a separation upper forming mold provided with suction enabling the glass to be held against it by the second principal face, after which the glass is separated from the gravity support by the separation upper forming mold and held by the separation upper forming mold in a separation chamber at a temperature lower than the temperature of the glass on the gravity support at the moment of separation, after which a cooling specific support able to support the glass without contact with the peripheral zone of its first principal face, being mobile laterally and able to enter or exit the separation chamber, is positioned under the glass and the separation upper forming mold releases the glass onto it, after which the cooling specific support carrying the glass exits the separation chamber for continued cooling of the glass.
17. The method as claimed in claim 16, wherein for continued cooling of the glass the cooling specific support carrying the glass enters the cooling chamber heated to a temperature lower than the temperature of the separation chamber, the cooling chamber being able to be at a temperature between 400 and 565° C.
18. The method as claimed in claim 1, wherein the gravity support carrying the glass is positioned under a separation upper forming mold provided with suction enabling the glass to be held against by the second principal face, after which the glass is separated from the gravity support by the separation upper forming mold and held against the separation upper forming mold in a separation chamber at a temperature lower than the temperature of the glass on the gravity support at the moment of separation, after which a preliminary specific support able to support the glass without contact with the peripheral zone of its first principal face, mobile laterally and able to enter or exit the separation chamber is positioned under the glass, after which the separation upper forming mold releases the glass onto it, after which the preliminary specific support carrying the glass exits the separation chamber and enters a transfer chamber equipped with a transfer upper forming mold provided with suction enabling the glass to be held against it by its second principal face, the temperature of the transfer chamber being lower than the temperature of the separation chamber, after which the glass is separated from the preliminary specific support by the transfer upper forming mold, after which a cooling specific support able to support the glass without contact with the peripheral zone of the first principal face, is positioned under the glass and the transfer upper forming mold releases the glass onto it, after which the cooling specific support carrying the glass exits the transfer chamber for continued cooling of the glass.
19. The method as claimed in claim 1, wherein the gravity support carrying the glass is positioned under a separation upper forming mold provided with suction enabling the glass to be held against it by the second principal face, after which the glass is separated from the gravity support by the separation upper forming mold and held against the separation upper forming mold in a separation chamber at a temperature lower than the temperature of the glass on the gravity support at the moment of separation, after which a bending suction lower mold able to bend the glass by suction on its first principal face, mobile laterally and able to enter or exit the separation chamber is positioned under the glass, after which the separation upper forming mold releases the glass onto it, after which the bending suction lower mold carrying the glass exits the separation chamber and enters a transfer chamber equipped with a transfer upper forming mold provided with suction means enabling the glass to be held against it by its second principal face, the temperature of the transfer chamber being lower than that of the separation chamber, the glass being bent on the suction lower mold in the separation chamber and/or the transfer chamber, after which the glass is separated from the suction lower mold by the transfer upper forming mold, after which a cooling specific support able to support the glass without contact with the peripheral zone of its first principal face is positioned under the glass and the transfer upper forming mold releases the glass onto it, after which the cooling specific support carrying the glass exits the transfer chamber for continued cooling of the glass.
20. The method as claimed in claim 18, wherein for continued cooling of the glass the cooling specific support carrying the glass enters a cooling chamber heated to a temperature lower than the temperature of the transfer chamber, the cooling chamber being able to be at a temperature between 350 and 520° C.
21. The method as claimed in claim 17, wherein a mean rate of cooling of the glass in the cooling chamber is between 0.8 and 2.5° C./s.
22. The method as claimed in claim 17, wherein an offloading support able to enter into contact with the first principal face of the glass without contact with the peripheral zone, enters the cooling chamber, passes under the glass and then rises to take charge of the glass and offload the glass from the cooling specific support, and then exits the glass from the cooling chamber, after which the glass is cooled to room temperature.
23. The method as claimed in claim 22, wherein the offloading support and the cooling specific support both comprise support elements comprising contact zones all of which come into contact with the glass exclusively in a contact band between an exterior limit and an interior limit, the exterior limit of the band being at least 50 mm from the edge of the glass, the interior limit of the band being at most 200 mm from the edge of the glass, contact areas of the offloading support and the cooling specific support being at least in part interleaved in the contact band at the moment of loading the glass onto the offloading support.
24. The method as claimed in claim 16, wherein a train of gravity supports each loaded with glass passes under the separation upper forming mold, the latter taking charge of the glass from each of the gravity supports one after the other.
25. The method as claimed in claim 1, wherein bending on the gravity support occurs at more than 590° C.
26. A device for bending and cooling glass in the form of a sheet or a stack of sheets, comprising a first principal face and a second principal face, the device comprising a gravity support able to bend the glass at its plastic deformation temperature while supporting the glass in a peripheral zone constituted of the 50 mm of the first principal face from the edge, a cooling specific support without contact with the peripheral zone, and a separation and transfer mechanism adapted to separate the glass from the gravity support and release the glass onto the cooling specific support, said separation and transfer mechanism comprising a separation upper forming mold provided with suction enabling the glass to be held against it by the second principal face, said separation upper forming mold being able to take charge of the glass and offload the glass from the gravity support.
27. The device as claimed in claim 26, wherein the separation and transfer mechanism comprises a separation chamber comprising the separation upper forming mold, the gravity support being mobile laterally and able to be positioned under the separation upper forming mold, the gravity support and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to take charge of the glass and offload the glass from the gravity support and then be moved away from the latter by rising in the separation chamber with the glass, the cooling specific support being mobile laterally and able to be positioned under the separation upper forming mold or to be moved away from that position, the cooling specific support and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to release the glass onto the cooling specific support.
28. The device as claimed in claim 26, wherein the separation and transfer mechanism comprises a separation chamber comprising the separation upper forming mold, a transfer chamber comprising a transfer upper forming mold provided with suction enabling the glass to be held against it by the second principal face, a preliminary specific support able to support the glass without contact with the peripheral zone of its principal face, the gravity support being mobile laterally and able to be positioned under the separation upper forming mold, the gravity support and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to take charge of the glass and offload the glass from the gravity support and then be moved away from the latter, the preliminary specific support being mobile laterally and able to enter the separation chamber, to be positioned under the separation upper forming mold, the preliminary specific support and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to release the glass onto the preliminary specific support and then be moved away from the latter, the preliminary specific support being able to exit the separation chamber loaded with the glass and to enter the transfer chamber and to be positioned under the transfer upper forming mold, the preliminary specific support and the transfer upper forming mold being able to be moved toward one another or away from one another so that the transfer upper forming mold is adapted to take charge of the glass and offload the glass from the preliminary specific support and then be moved away from the latter, the cooling specific support being mobile laterally and able to enter or exit the transfer chamber and to be positioned under the transfer upper forming mold or to be moved away from that position, the cooling specific support and the transfer upper forming mold being able to be moved toward one another or away from one another so that the transfer upper forming mold is adapted to release the glass onto the cooling specific support.
29. The device as claimed in claim 26, wherein the separation and transfer mechanism comprises a separation chamber comprising the separation upper forming mold, a transfer chamber comprising a transfer upper forming mold provided with suction enabling the glass to be held against it by the second principal face, a bending suction lower mold able to bend the glass by suction on its first principal face, the gravity support being mobile laterally and able to be positioned under the separation upper forming mold, the gravity support and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to take charge of the glass and offload the glass from the gravity support, the suction lower mold being mobile laterally and able to enter the separation chamber, to be positioned under the separation upper forming mold, the suction lower mold and the separation upper forming mold being able to be moved toward one another or away from one another so that the separation upper forming mold is adapted to release the glass and press it the glass onto the suction lower mold and then be moved away from the latter, the suction lower mold being able to exit the separation chamber loaded with the glass and to enter the transfer chamber and be positioned under the transfer upper forming mold, the suction lower mold and the transfer upper forming mold being able to be moved toward one another or away from one another so that the transfer upper forming mold is adapted to take charge of the glass and offload the glass from the suction lower mold and then be moved away from the latter, the cooling specific support being mobile laterally and able to enter or exit the transfer chamber and to be positioned under the transfer upper forming mold or to be moved away from that position, the cooling specific support and the transfer upper forming mold being able to be moved toward one another or away from one another so that the transfer upper forming mold is adapted to release the glass onto the cooling specific support.
30. The device as claimed in claim 26, further comprising a cooling chamber, the cooling specific support loaded with the glass being able to enter the cooling chamber and to exit the cooling chamber offloaded of the glass, an offloading support able to support the glass without contact with the peripheral zone of the first principal face, being able to rise to take charge of the glass and offload the glass from the cooling specific support and to exit the cooling chamber loaded with the glass.
31. The device as claimed in claim 30, wherein the offloading support and the cooling specific support both comprise support elements comprising contact zones all of which come into contact with the glass exclusively in a contact band substantially parallel to the edge of the glass at most 150 mm wide, contact zones of the offloading support and of the cooling specific support being at least in part interleaved in the contact band at the moment of the transfer of the glass from the cooling specific support to the offloading support.
32. The device as claimed in claim 30, wherein seen from above and in orthogonal projection in a horizontal plane, at the moment of the transfer of the glass from the cooling specific support to the offloading support, at least one support element of the cooling support intersects the straight line tangential to exterior edges of two contact zones of adjacent support elements of the offloading support, the intersection occurring between two adjacent support elements of the offloading support.
33. The device as claimed in claim 26, wherein a train of gravity supports each of which is adapted to be loaded with glass is able to circulate under the separation upper forming mold, the latter being able to take charge of the glass from each of the gravity supports one after the other.
Description
[0087] FIGS. 1 to 6 show a device according to the invention at various stages of the treatment of glass moving one behind the other. Here the glass is bent only by gravity. In FIG. 1, the glass is conveyed from right to left and undergoes bending by gravity. This device comprises a train 30 of gravity supports 31 each carrying a glass 32. This train circulates at a lower level 34 of the device, in a tunnel furnace heated to the plastic deformation temperature of the glass. As it is conveyed, the glass sags under its own weight until it finally espouses the track of the gravity support 31 under the periphery of the first principle face of the glass. Each support carrying a glass arrives under a vertically mobile upper forming mold 33 able to pass from the upper level 35 to the lower level 34 and vice versa. This upper forming mold 33 is in a separation chamber 36 the atmosphere in which is at a temperature between 540 and 580° C. This upper forming mold 33 comes into contact with the glass only at the periphery of its second principal face. The contact track of this upper forming mold 33 has a shape complementary to that of the gravity supports 31. The upper forming mold 33 can take charge of the glass at the lower level 34 by suction thanks to a skirt 46 surrounding it. At the upper level 35 is the laterally mobile cooling specific support 37 shuttling between a position under the upper forming mold 33 in the chamber 36 and a cooling chamber 38 heated to a temperature between 400 and 565° C. A system of chains 47 enables lateral movement of the cooling specific support between the chambers 36 and 38. There is a door 39 on the structure carrying the cooling specific support and it therefore moves with the latter. This door therefore closes the partition between the chambers 36 and 38 when the cooling specific support is in the chamber 38. When it is in the chamber 36, this door is against the right hand bulkhead of the chamber 36 as seen in the figure. Instead of being on the support 37, a vertically mobile door could have been installed on the wall separating the chambers 36 and 38 and, provided with sides and a raising and lower system, provide the isolation function required between the chambers 36 and 38. The glass may be offloaded from the specific support 37 by an offloading support 40 carried by an arm 42 of a robot 41. To this end, the offloading support 40 is engaged under the glass still being carried by the specific support 37, rises and takes charge of the glass as it rises, after which it exits the chamber 38 carrying the glass. The robot 41 then drives the offloading support 40 carrying the glass toward a final device 49 tasked with taking charge of the glass to convey it to a cooling zone enabling offloading and storage of the glass. The cooling specific support 37 is of the type from FIG. 20a referenced 401. The offloading support 40 is of the type from FIG. 20b referenced 400. In FIG. 1 the glass 32 arrives under the upper forming mold 33, the train then stopping. The robot has previously already offloaded a glass 51 onto the final device and more specifically onto four vertically mobile bars 52. A conveyor 53 circulates between the bars 52. This conveyor drives the supporting elements 54 (for example suckers) able to receive the glass when the bars 52 are lowered. The glass then rests on support elements 54 and is driven by the conveyor 53 toward a cooling zone in which it is offloaded and then stored. The device 49 is not shown in the other FIGS. 2 to 6 to simplify the representation. FIG. 2 represents a stage after that from FIG. 1. In FIG. 2, the upper forming mold 33 descends as far as the glass 32 to take charge of it. During this time the robot 41 engages its offloading support 40 under the cooling specific support 37 and then rises to take charge of the preceding glass 29. The forming mold 33 rises with the glass 32, after which the empty cooling specific support 37 passes from the chamber 38 to the chamber 36. The upper forming mold 33 is lowered, releases the glass 32 onto the cooling specific support 37 and rises again (FIG. 3). Simultaneously, the train 30 of gravity supports 31 has advanced one step to the left, therefore bringing the next glass 45 under the upper forming mold 33. During this time, the preceding glass 29 has exited the chamber 38 and the robot 41 places it on the conveyor 49 to continue its cooling. The support 37 carrying the glass 32 then enters the chamber 38. In parallel with this another glass 45 is taken charge of by the upper forming mold 33 which is lowered as far as the train of gravity supports 30 at the lower level 34. The door 44 is raised and the robot 41 engages the offloading support 40 under the cooling specific support 37 (FIG. 4). The robot raises the offloading support 40 so that the latter takes charge of the glass 32. In parallel with this, the upper forming mold 33 rises with the glass 45 in the chamber 36 (FIG. 5). The robot then exits the support 40 carrying the glass 32 from the chamber 38, after which the door 44 descends again. In parallel with this, the cooling specific support 37 has passed from the chamber 38 to the chamber 36 and the forming mold 33 has been lowered to release the glass 45 onto the support 37 (FIG. 6). The robot then places the glass 32 on the device 49, which then drives it toward the final cooling zone. The glass 45 then undergoes the same treatment as that undergone by the glass 32. The temperature homogenization of the peripheral zone of the first principal face of the glass begins as soon as the glass is separated from the bending support 31. The peripheral zone of the first principal face of the glass is then free of all contact whereas the glass is held by the upper forming mold 33 and then supported by the cooling specific support 37 and then the offloading support 40.
[0088] FIGS. 7 to 13 show a method and a device according to the invention at various stages of the treatment of glass fed one after the other. Compared to the preceding device from FIGS. 1 to 6, the glass undergoes a step of bending by suction between bending by gravity on a gravity support and being placed on the cooling specific support. The process undergone by the glass in the context of this variant is described hereinafter.
[0089] The device comprises a train 130 of gravity supports 131 each carrying a glass. This train circulates at a lower level 134 of the device, in a tunnel furnace heated to the plastic deformation temperature of the glass. During its conveyance (from right to left in the figures), the glass sags under its own weight finally to espouse the contact track of the gravity support 131 under the periphery of the first principal face of the glass. Each support finally arrives under a vertically mobile upper forming mold 233 able to pass from the upper level 135 to the lower level 134 and vice versa. This upper forming mold 233 is in a chamber 236 the atmosphere in which is at a temperature between 550 and 590° C. The contact track of this upper forming mold 233 has a shape complementary to that of the suction mold 200. The upper forming mold 233 can take charge of the glass at the lower level 134 by suction thanks to the skirt 240 surrounding it. At the upper level 135 is located a suction lower mold 200 the face 201 of which in contact with the glass is solid and includes orifices in order to communicate vacuum to the first principal face of the glass in the lower position. This mold 200 shuttles between a position under the upper forming mold 233 in the chamber 236 and a juxtaposed chamber 136 heated to a temperature between 500 and 560° C. This chamber 136 contains a vertically mobile upper forming mold 133 able to take charge of the glass thanks to a skirt 241. At the upper level 135 is also located a laterally mobile cooling specific support 137 shuttling between a position under the upper forming mold 133 in the chamber 136 and a position in the cooling chamber 138, the temperature in which is between 350 and 520° C. A door 139 on the structure carrying the cooling specific support 137 therefore moves with it. This door therefore closes the bulkhead between the chambers 136 and 138 when the cooling specific support is in the chamber 138. It closes the bulkhead between the chambers 136 and 236 when the cooling specific support 137 is in the chamber 136. A door 239 on the structure carrying the suction lower mold 200 therefore moves with it. This door 239 therefore closes the bulkhead between the chambers 136 and 236 when the suction lower mold 200 is in the chamber 136. The support 137 and the mold 200 move simultaneously in translation, as if they were fastened to one another and without modification of the distance that separates them. The glass is offloaded from the cooling specific support 137 by the offloading support 140 held by the arm 142 of a robot 141. The cooling specific support 137 is of the type from FIG. 20a referenced 401. The offloading support 140 is of the type from FIG. 20b referenced 400.
[0090] In FIG. 7, the glass 132 arrives under the upper forming mold 233, the train 130 then stopping. The upper forming mold 233 descends as far as the glass 132 to take charge of it (FIG. 8). This forming mold rises with the glass, after which the empty (with no glass) suction lower mold 200 passes from the chamber 136 to the chamber 236, and likewise the cooling specific support 137 passes empty from the chamber 138 to the chamber 136 (FIG. 9). The upper forming mold 233 is lowered with the glass, and then presses lightly on its periphery in order to seal the periphery of the glass between the glass and the mold 200 on the one hand and between the various sheets of the stack. The suction by the skirt of the forming mold 233 is stopped simultaneously with this pressing. The suction of the suction lower mold is triggered when this light pressing has already begun. The glass is then bent on the suction lower mold and all the sheets of the stack simultaneously undergo bending because of the pressure exerted at the periphery, the vacuum being communicated from one sheet to the other. The forming mold 233 rises again, leaving the glass on the mold 200. The mold 200 carrying the glass 132 enters the chamber 136 under the upper forming mold 133. The suction exerted by the mold 200 is stopped when the bending is finished, which generally occurs in the chamber 236 just before the upper forming mold 233 is raised. In the meantime, the train 130 of gravity supports 131 has advanced one step to the left, therefore bringing the glass 145 under the upper forming mold 233. The upper forming mold 133 is lowered (FIG. 10) to take charge of the glass 132 and rises with it. In parallel with this, the upper forming mold 233 is lowered also to take charge of the next glass 145. The support 137 passes empty from the chamber 138 to the chamber 136 and the mold 200 passes simultaneously from the chamber 136 to the chamber 236. The upper forming mold 133 releases the glass 132 onto the cooling specific support 137 and the upper forming mold 233 is lowered to press the glass 145 against the mold 200 (FIG. 11), as already described for the glass 132 (the treatment of the glass 145, which is identical to that of the glass 132, is not described further). The support 137 carrying the glass 132 enters the chamber 138. The door 144 is raised and the robot 141 engages the offloading support 140 under the cooling specific support 137 (FIG. 12). The robot then causes the offloading support 140 to rise for the latter to take charge of the glass 132. The robot then exits the offloading support 140 carrying the glass 132 from the chamber 138 and the door 144 descends again. The robot then places the glass 132 on a final device 49 identical to that already described for FIGS. 1 to 6, for continued cooling (FIG. 13).
[0091] FIG. 14 shows a device identical to that of FIGS. 7 to 13 except that the suction lower mold is replaced by a preliminary specific support 603. The movement of the various elements of this device is identical to that from FIGS. 7 to 13, from the gravity support 601 as far as the final device 49. However, here the glass reaches its final shape on its gravity support 601 under the separation chamber 600. Another difference compared to the system from FIGS. 7 to 13 is that the glass is not lightly pressed at the periphery against the forming mold 602 and the preliminary specific support 603. The glass is simply released by the forming mold 602 onto the support 603.
[0092] FIG. 15 shows the evolution of the stresses at the edges of a sheet of glass 1 in the direction away from the edge 2 toward the center of the sheet, at a) for a sheet conventionally obtained in accordance with the prior art and at b) for a sheet obtained in accordance with the present invention. The distance from the edge is plotted on the abscissa axis and the stresses in the glass on the ordinate axis. The stresses below the abscissa axis are compression stresses. Those above the abscissa axis are tension stresses. According to the prior art (a), the tension stresses usually exceed 5 MPa, which is high. According to the invention, the maximum tension stress may be only 3 MPa which is very favorable to the mechanical strength of the sheet, compared to case a).
[0093] FIG. 16 represents the lower face of a bent sheet of glass. The dashed line 25 is located 50 mm from the edge of the sheet and indicates the end of the peripheral zone. The line 28 indicates the exterior limit of the contact band for the contact zones of the specific supports. This exterior limit may coincide with the line 25 or preferably come to within at least 60 mm and even 70 mm from the edge. The line 26 indicates the interior limit of the contact band for the contact zones of the specific supports. The cross-hatched zone 27 between the edge of the glass and the line 25 is the peripheral zone. The plane P is an imaginary plane perpendicular to the edge of the glass and to the sheet. The intersection of the plane P with the lower face defines a segment S. According to the invention, the temperature is homogenized over the 50 mm of this segment starting from the edge of the sheet. The specific supports coming into contact with the glass in the critical temperature range preferably touch the glass in the zone 161 and without coming into contact with the glass outside the zone 161.
[0094] FIG. 17 represents the respective positions of a frame-shaped upper forming mold 160, a glass 162 and a specific support 163 of the type coming into contact with the glass in the central zone (inside the interior limit of the peripheral zone). This situation can arise when the upper forming mold takes charge of the glass initially on the specific support or the upper forming mold releases the glass onto the specific support. The glass is taken charge of following the initiation of suction between the skirt 164 and the upper forming mold 160. The upper forming mold 160 comes into contact with the second principal face of the glass with the result that its exterior edge 164 arrives at a distance dl from the edge of the glass in the range from 3 to 20 mm. The distance d2 corresponds to the peripheral zone. The distance d3 is the distance between the exterior edge of the contact zone of the specific support 163 and the edge of the glass. The distance between the exterior edge of the upper forming mold and the exterior edge of the contact zone of the specific support is d3-d1, which is greater than 30 mm.
[0095] FIG. 18 shows a cooling specific support 10 able to receive the glass (here a stack of two sheets of glass 11 and 12 one on the other) without contact with the peripheral zone of its downward-facing first principal face 19. This support offers to the glass a shape complementary to that which it receives through bending. This support comprises a multiplicity of aligned crenellations 13. The upper face 14 of each crenellation is designed to receive the first principal face 19 of the glass in the “contact band” in the central zone of the glass. To soften the contact of a tool with the hot glass each crenellation 13 is covered with a refractory fiber fibrous material 15 well known to the person skilled in the art. The contact zone formed by the upper faces of the crenellations (represented by the cross-hatched zone 17 in the figure) comes into contact with the glass at a distance d greater than 50 mm from the edge 16 of the glass around the entire periphery of the glass. This support 10 is a frame one side of which includes a passage 18 to allow passage of the arm of an offloading support that comes to take charge of the glass from below.
[0096] FIG. 19 represents a cooling specific support 301 of the peripheral track type carrying a stack of two sheets of glass. The glass 300 rests cantilever-fashion via the lower intersection line 132 of its edge surface on the peripheral track. The glass therefore has no contact with the support in the peripheral zone of its first principal face 133, enabling the homogenization in accordance with the invention to be produced and preserved.
[0097] FIG. 20 shows how an offloading support can take charge of a glass when the latter is carried by a cooling specific support 401. This glass intended for a windshield comprises four bands. At a) is seen from the side the empty cooling specific support 401 with its support elements 411. Its chassis 410 provides a free space 413 allowing the offloading support 400 to penetrate to the interior of the chassis 410 under the glass (not shown at a)). FIGS. 20b to 20d show sequentially the passage of a glass 407 from a cooling specific support 401 to an offloading support 400. At b), the empty offloading support 400 is manipulated by a robot (not shown) actuating the arm 406. It approaches the cooling specific support 401 carrying a glass 407. The offloading support comprises a chassis 402 carrying a plurality of support elements 403. These support elements 403 are connected by one end 404 to the chassis 402 and have at their other end 405 a contact zone that comes into contact with the glass. Seen from above, the support elements 403 are directed toward the exterior of the chassis 402 in the direction from the end 404 to the end 405. At b) the cooling specific support 401 carries a glass 407 by means of a plurality of support elements 408. This cooling specific support 401 comprises a chassis 410 and a plurality of support elements 408. These support elements 408 are connected by one end 409 to the chassis 410 and have at their other end 411 a contact zone that comes into contact with the glass. Seen from above, the support elements 408 are directed toward the interior of the chassis 410 in the direction from the end 409 to the end 411. The chassis 401 comprises a passage 412 to enable the support 400 to rise (see phase c)) without immobilizing it. At c), the offloading support 400 has been placed under the glass as yet without touching it. At d), the offloading support 400, actuated by the robot, has risen and has taken charge of the glass 407, offloaded from the cooling specific support 401. This is made possible thanks to the passage 412 in the chassis 401 allowing the arm 406 of the offloading support 400 to pass and thanks to the fact that the support elements 403 and 408 are offset as seen from above, the support elements 403 extending toward the exterior whereas the support elements 408 extend toward the interior. Accordingly, when the support 400 rises, the support elements 403 on the one hand and the support elements 408 on the other hand cross in the manner of the teeth of two combs. Thus the contact zones of the two supports 400 and 401 can both come into contact with the glass in the same “contact band” (between 50, or even 60, or even 70 mm from the edge of the glass and 200 or even 170 mm or even 150 mm from the edge of the glass) as defined above, without contacting the glass outside this band. The support elements 403 and 408 preferably have their contact zone adapted to the shape of the glass that they receive, that is to say their contact zone is oriented toward the glass and is therefore substantially parallel to the zone of the glass received. The support elements may moreover comprise a spring to damp the reception of the glass at the moment it is taken charge of. In FIG. 20e, there are seen from above and in orthogonal projection in a horizontal plane the two supports at the moment of the transfer of the glass 407 from the cooling specific support to the offloading specific support. It is seen that the contact zones of the two supports 405 and 411 all come into the “contact band” between the line 26 (interior limit of the contact band at the distance dy from the edge, dy being at most 200 or even at most 170 mm or even at most 150 mm) and the line 28 (exterior limit of the contact band at the distance dx from the edge with dx being at most 50 or even at most 60 or even at most 70 mm). This contact band is therefore at most 150 mm wide (200−50=150) or even at most 100 mm wide (170−70=100) or at most 80 mm wide (150−70=80). Moreover, the contact zones of the offloading support and of the cooling specific support are at least in part interleaved in the contact band. At the moment of the transfer of the glass from one support to the other at least one contact zone of a support has for its immediate neighbors two contact zones of the other support. It is seen that at the moment of the transfer of the glass the straight line 414 tangential to the exterior edges of two contact zones 415 and 416 of two adjacent support elements of the offloading support come to intersect a support element 417 of the cooling support. This actuation occurs for a plurality of support elements of the cooling support. It is also seen that the straight line segment passing through the centers 418 and 419 of the contact zones 415 and 416 of two adjacent support elements of the offloading support come to intersect the support element 417 of the cooling support. This situation occurs for a plurality of support elements of the cooling support. This reflects the fact that the contact zones of the two supports are interleaved in a narrow band parallel to the edge of the glass. It is seen that when dy is equal to 200 mm the central region of the lens situated inside the line 26 (zone of the glass farther than 200 mm from the edge) can easily contain an imaginary circle of 100 mm diameter and even of 200 mm diameter and even larger (for example 500 mm or even 1000 mm in diameter), not touching the line 26. This property reflects the size of the principal faces of the glass.
[0098] FIG. 21 shows how an offloading specific support 750 can come to take charge of a glass (not shown) initially supported by a track type cooling specific support 751. This track forms, seen from above, an interrupted frame because it comprises a passage 752 enabling an arm 753 connected to the offloading support 750 to pass through it by a vertical movement. The support 750 therefore comes underneath, rises, takes charge of the glass initially supported by the support 751 and can move the glass on to the next step. The support 750 carries the glass by means of support elements 754.
[0099] FIGS. 22 and 23 show support elements that can equip a cooling specific support or an offloading support. In FIG. 22a, the support element 500 comprises at one of its ends a base 501 provided with orifices enabling it to be fixed to a chassis. The other end comprises a contact zone 502 covered with a fibrous material 508 to come into contact with the glass. The open texture fibrous material 508 is retained on the surface of the element by lugs 503. The contact zone 502 is mobile in translation in a direction that is perpendicular to it and its downward movement is accompanied by the compression of a spring 504. The reception of a glass by a contact zone 502 is therefore damped by the spring 504. In FIG. 22b is seen the same support element as in FIG. 22a except that the spring 504 has been removed as well as the part comprising the base 501. It is seen in this figure b) that a cup 505 is able to receive the spring 504. It is also seen that the rod 506 is guided in the tube 507 so that the contact zone 502 can move only in a direction corresponding to the axis of the tubular guide 507. Figure c) shows the support element the contact zone of which is fitted with its knitted type open texture refractory fibrous material 508 to come into contact with the glass.
[0100] FIG. 23 shows another support element provided with a contact zone 601 surrounded by lugs 602 enabling the retention of a perforated refractory material (not shown) on the surface of the contact zone. Compared to the element from FIG. 22, there is no guide obliging the contact zone to retain its orientation. This absence of a guide confers a supplementary degree of freedom on the contact zone, which can not only move parallel to the axis of the spring 604 (arrow 603) but also turn so that the perpendicular to the contact zone moves away from the axis of the spring 604 (arrow 605 or 606). This faculty of being orientable is exploited when an element of this kind receives a glass where the local orientation of the surface does not correspond exactly to that of the contact zone. In this case, because of the weight of the glass, the contact zone 601 is automatically oriented to take exactly the orientation of the surface of the glass. Such behavior confers on the support comprising such support elements a more universal character in that the same support can adapt to different shapes of glass.
