[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 61/679227 filed on August 3, 2012 the content of which is relied upon and incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to chambers and methods for heat-treating sheets of glass and, more particularly, chambers and methods for heat-treating sheets of glass so as to densify the glass and lower the Active temperature of the glass.

BACKGROUND

[0003] Glass used in display devices typically undergoes thermal processing after being rendered in a sheet form. In order to prepare the sheets of glass for downstream processes, the sheets sometimes undergo thermal processing, for example a time-temperature cycle, in order to densify the glass and lower the Active temperature of the glass.

SUMMARY

[0004] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the various aspects as exemplified in the written description and the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the various aspects, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed.

[0005] The accompanying drawings are included to provide a further understanding of principles of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain, by way of example, principles and operation of the invention. It is to be understood that various features disclosed in this specification and in the drawings can be used in any and all combinations. By way of non-limiting example the various features may be combined with one another as set forth in the following aspects:

[0006] According to a first aspect, there is provided a chamber for heat-treating sheets of glass, the chamber including: a horizontal passage including a first end and a second end;

a first vertical passage in communication with the first end; and

a second vertical passage in communication with the second end, wherein the first vertical passage is upstream of the horizontal passage which is upstream of the second vertical passage, and

wherein a cross-section of the first vertical passage and a cross-section of the second vertical passage are dimensioned to be marginally larger in width and in thickness than the sheets of glass, and a cross-section of the horizontal passage is dimensioned to be marginally larger in height and in width than the sheets of glass.

[0007] According to a second aspect, there is provided the chamber of aspect 1, wherein the horizontal passage is located above the first vertical passage and the second vertical passage.

[0008] According to a third aspect, there is provided the chamber of aspect 1 or aspect 2, wherein substantially all inner surfaces defining the horizontal passage, the first vertical passage, and the second vertical passage are covered with heating elements.

[0009] According to a fourth aspect, there is provided the chamber of aspect 3, further including deflectors mounted in-between two of the heating elements of the first vertical passage and in-between two of the heating elements of the second vertical passage.

[0010] According to a fifth aspect, there is provided the chamber of any one of aspects 1-

4, further including a clamp that is suspended about a rod that is disposed in the chamber.

[0011] According to a sixth aspect, there is provided the chamber of aspect 5, further including a first pulley apparatus and a second pulley apparatus configured to move the rod in the first vertical passage and the second vertical passage respectively, each of the pulley apparatuses including a belt with cups configured to support the ends of the rod.

[0012] According to a seventh aspect, there is provided the chamber of aspect 5 or aspect

6, further including a conveyor configured to move the rod in the horizontal passage.

[0013] According to an eighth aspect, there is provided the chamber of aspect 7, wherein the conveyor is a walking beam conveyor including a fixed beam and a moving beam, the first pulley apparatus configured to place the ends of the rod on the fixed beam, the second pulley apparatus configured to pick up the ends of the rod from the fixed beam, the moving beam configured to advance the ends of the rod along the fixed beam. [0014] According to a ninth aspect, there is provided the chamber of aspect 7, wherein the conveyor extends through walls defining the horizontal passage and a bellows is configured to provide sealing between the conveyor and the walls.

[0015] According to a tenth aspect, there is provided a method of heat-treating sheets of glass, including steps of:

moving sheets in a first vertical column in which the sheets are vertically oriented, the first vertical column substantially enclosed by a first set of heating elements;

moving the sheets in a horizontal row in which the sheets are oriented vertically, the horizontal row substantially enclosed by a second set of heating elements; and

moving the sheets in a second vertical column in which the sheets are vertically oriented, the second vertical column substantially enclosed by a third set of heating elements.

[0016] According to an eleventh aspect, there is provided the method of aspect 10, wherein the sheets are heated to 350 °C or above during the step of moving the sheets in the first vertical column, the sheets are heated to a temperature range and maintained in the temperature range for a predetermined time so as to reduce a Active temperature to a given point during the step of moving the sheets in the horizontal row, and the sheets are cooled to a temperature of 200 °C or less during the step of moving the sheets in the second vertical column.

[0017] According to a twelfth aspect, there is provided the method of aspect 11, wherein the sheets are heated to a temperature which is in the range of 600-750 °C.

[0018] According to a thirteenth aspect, there is provided the method of any one of aspects 10-12, wherein the first set of heating elements, the second set of heating elements, and the third set of heating elements are configured to transfer heat through radiation.

[0019] According to a fourteenth aspect, there is provided the method of any one of aspects 10-13, further including a step of making the sheets of glass from a glass ribbon.

[0020] According to a fifteenth aspect, there is provided the method of aspect 14, further including the step of making the glass ribbon with a fusion down draw method.

[0021] According to a sixteenth aspect, there is provided the method of aspect 15, wherein the sheets are raised to a height from which glass is drawn in the fusion down draw method through the step of moving the sheets in the first vertical column. [0022] According to a seventeenth aspect, there is provided the method of any one of aspects 10-16, wherein at least one edge of the sheets includes a bead portion therealong.

[0023] According to an eighteenth aspect, there is provided the method of aspect 17, wherein the sheets are moved by pinching the at least one edge of the sheets during the steps of moving the sheets in the first vertical passage, the horizontal passage, and the second vertical passage.

[0024] According to a nineteenth aspect, there is provided the method of aspect 17 or aspect 18, further including a step of cutting off the at least one edge of the sheets.

[0025] According to a twentieth aspect, there is provided the method of any one of aspects 17-19, wherein the bead portion is formed along two edges of the sheets.

[0026] According to a twenty-first aspect, there is provided the method of aspect 20, further including a step of attaching a weight clamp to the sheets of the glass on one of the two edges opposite the at least one edge.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other aspects are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0028] FIG. 1 is a perspective view of an example embodiment of an apparatus for heating sheets of glass;

[0029] FIG. 2 is a cross-sectional view of the example apparatus including a chamber with a first vertical passage, a horizontal passage and a second vertical passage;

[0030] FIG. 3 is a perspective view of an example embodiment of the transport apparatus including a first pulley apparatus, a conveyor and a second pulley apparatus;

[0031] FIG. 4 is a close-up view of bottom pulleys and cups of the first pulley apparatus;

[0032] FIG. 5 is a close-up, first side view of the top pulleys and the conveyor;

[0033] FIG. 6 is a close-up, second side view of the conveyor;

[0034] FIG. 7 is a perspective, isolated view of an example embodiment of an assembly including a rod and a pair of clamps for pinching a sheet of glass; and

[0035] FIG. 8 is a cross-sectional view of pads and inner portions of the clamps pinching a sheet of glass.

DETAILED DESCRIPTION [0036] Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0037] Referring now to FIG. 1, an example embodiment of an apparatus 10 for heat- treating sheets of glass 12 is illustrated. The apparatus 10 may be used to thermally process the sheets of glass 12 for purposes of, for example, compaction, annealing, strain relief or the like. The sheets of glass 12 may be formed into a sheet by a variety of processes known in the art for example a fusion down draw method. In case the fusion down draw method is used for making the sheets of glass 12, the apparatus 10 may be located near the bottom of the draw in order to reduce time for transportation of the sheets 12.

[0038] The apparatus 10 is embodied as a chamber 14 for heating sheets of glass 12. As shown in FIG. 2, the chamber 14 may include a number of interior passages through which one or more sheets of glass 12 are moved. Specifically, the chamber 14 may include a first vertical passage 16, a horizontal passage 18 and a second vertical passage 20 and the chamber 14 is configured in an inverted U-shape. The horizontal passage 18 may include a first end 18a and a second end 18b with the first vertical passage 16 in communication with the first end 18a and the second vertical passage 20 in communication with the second end 18b. The horizontal passage 18 may be located above the first vertical passage 16 and the second vertical passage 20.

[0039] Movement of the sheets of glass 12 inside the chamber 14 may be in the following sequence: upward in the first vertical passage 16, from the first end 18a to the second end 18b in the horizontal passage 18 and downward in the second vertical passage 20. Thus, the first vertical passage 16 is upstream of the horizontal passage 18 which is upstream of the second vertical passage 20. Moreover, the sheets of glass 12 may be configured to maintain a substantially vertical orientation during the entire duration of movement through the chamber 14. Furthermore, in case a fusion down draw method is used to form the sheets of glass 12, a height of the chamber 14 may extend to a height of the glass sheet manufacturing facility, for example a height of a draw 13 of a ribbon of glass in case of fusion down draw method.

[0040] As shown in FIG. 2, substantially all inner surfaces of the horizontal passage 18, the first vertical passage 16 and the second vertical passage 20 may be covered with heating elements 22 that transfer heat to the space inside the passages 16, 18 and 20. Specifically, the first vertical passage 16, the horizontal passage 18 and the second vertical passage 20 may include a first set of heating elements 22, a second set of heating elements 22 and a third set of heating elements 22 respectively. Alternately, the heating elements 22 may be located inside the walls 24 that form the chamber 14 but sufficiently close to the inner surfaces so as to cause heat transfer from the heating elements 22 to the passages 16, 18 and 20. The heating elements 22 may be embodied as resistive coils or wires that can transfer heat by way of radiation. For example, the heating elements 22 may be nichrome wires wrapped around an alumina tube, nichrome wires coiled inside a quartz tube, silicon carbide rods or loops of molybdenum disilicide. Moreover, external portions of the walls 24 of the chamber 14 may include insulation to reduce heat escaping from the passages 16, 18 and 20 through the walls 24. There may be thermocouples located inside the passages 16, 18 and 20 in order to sense and adjust temperatures therein as desired.

[0041] The heating elements 22 may be divided into sections along the first vertical passage 16, the horizontal passage 18 and the second vertical passage 20 so that the intensity of the heating elements 22 in a given section are adjustable as one. The division of the heating elements 22 may form rows or columns of segmented heating elements such that uniform temperature or precise temperature gradients can be achieved.

[0042] Also, the dimensions of the passages 16, 18 and 20 may be such that the heating elements 22 are positioned sufficiently close to the sheets of glass 12 in order to accomplish effective heat transfer. For example, the sheets of glass 12 that move through the chamber 14 may have a given set of height, width, and thickness, dimensions, and the cross-section of the first vertical passage 16 and a cross-section of the second vertical passage 20 may be dimensioned to be marginally larger in width and thickness than the sheets of glass 12 while a cross-section of the horizontal passage 18 may be dimensioned to be marginally larger in width and height than the sheets of glass 12.

[0043] As shown in FIG. 2, the first vertical passage 16 and the second vertical passage

20 may include deflectors 26 mounted in-between two of the heating elements 22. In case broken pieces or fragments of glass 12 are generated in the vertical passages 20, the deflectors 26 are configured to channel these pieces or fragments of glass downward in the first vertical passage 16 and the second vertical passage 20. The deflectors 26 can also reduce undesired flow of air up or down the first and second vertical passage 16 and 20 such that movement of contaminating particles can be restricted.

[0044] FIG. 3 shows a transport apparatus 28 for moving the sheets of glass 12 through the chamber 14. The transport apparatus 28 may be housed substantially inside the chamber 14 and may include a first pulley apparatus 30, a conveyor 32 and a second pulley apparatus 34. The first and second pulley apparatuses 30, 34 may be configured to move the sheets of glass 12 upward in the first vertical passage 16 and downward in the second vertical passage 20 respectively while the conveyor 32 is configured to move the sheets of glass 12 from the first end 18a to the second end 18b of the horizontal passage 18. While the first pulley apparatus 30 and the second pulley apparatus 34 may include pulleys, the term "pulley" should be interpreted to encompass similarly operating mechanisms, for example a chain and a sprocket.

[0045] The sheets of glass 12 may be moved while being pinched by a clamp assembly

36 shown in FIGS. 7-8. While other embodiments may be contemplated by one of ordinary skill in the art, the example embodiment of the clamp assembly 36 may include a rod 38 which is a transversely extending member and by which the clamp assembly 36 may be held for movement. One or more clamps 40 may be pivotally coupled to the rod 38 with each clamp 40 pinching an edge 12a of the sheet of glass 12. A pair of clamps 40 is used in this embodiment of the apparatus 10 and the sheet of glass 12 becomes suspended about the rod 38. As shown in FIG. 8, the clamp 40 may be a linkage including a plurality of pivotally coupled members allowing the clamp 40 to assume an open position and a closed position. In this embodiment, the clamp 40 includes a pair of proximal members 42 and a pair of distal members 44. Each of the proximal members 42 includes a first proximal section 42a and a first distal section 42b while each of the distal members 44 includes a second proximal section 44a, an intermediate section 44b and a second distal section 44c. Each of the first proximal sections 42a is pivotally coupled to the rod 38. The distal members 44 are pivotally coupled to one another at the intermediate sections 44b so as to be movable in a scissor-like fashion. Each second proximal section 44a of the distal members 44 is pivotally coupled to a corresponding one of the first distal sections 42b of the proximal members 42. Each of the second distal section 44c of the distal members 44 terminates in a pad 46 and is inwardly bent such that an edge of a sheet of glass 12 can be pinched between the pads 46 when the clamp 40 assumes a closed position and can be released from the pads 46 when the clamp 40 assumes an open position. [0046] As shown in FIG. 8, the pads 46 may include an inner portion 48 that is configured to contact the sheet of glass 12. A number of mechanisms may be contemplated to secure the sheet of glass 12 to the clamp 40. A factional force between the inner portion 48 and a surface of the sheet of glass 12 engaged by the inner portion 48 may be sufficient to keep the clamp 40 in the closed position. In an alternative embodiment, the surface of the sheet of glass 12 may include a feature (e.g., a bead) that can mate or be engaged by a corresponding feature (e.g., a recessed area) in the inner portion 48. For example, the inner portion 48 may include alternating recessed areas and protruding areas, and the bead may be contoured to fit within the recessed area. In another alternative embodiment, the inner portion 48 may be formed of material that is deformable but provides sufficient rigidity so as to pinch and secure the sheet of glass 12 between the pads 46. Moreover, the inner portion 48 may be a part of the pad 46 that gradually becomes worn so as to require replacement and the inner portion 48 may be configured to be readily attached to and detached from the pad 46 so as to be replaceable.

[0047] Sheets of glass 12 made by the fusion down draw method are drawn in a downward direction by a set of rollers that engage the lateral edges of a ribbon of glass. The engagement by the rollers leaves beads along the lateral edges of the sheets 12 cut from the ribbon and the beads may act as the protruding feature that is engaged by the inner portion 48. A robot arm 60 (FIG. 2) with vacuum cups or grippers may be used to rotate the orientation of the sheets of glass 12 such that the beaded edges can be pinched by the clamps 40 which are shown schematically in FIG. 2.

[0048] As shown in FIG. 7, a bottom edge 12b of the sheet of glass 12 may be also pinched by a second pair of clamps 40 such that warping is reduced by gravity and the sheet of glass 12 is made straighter when the sheets of glass 12 are suspended from the rod 38. Attaching the second pair of clamps 40 to the bottom edge may 12b also reduce the likelihood of the sheets of glass 12 swinging back and forth about the rod 38. In case of the sheets of glass 12 engaged by rollers in the fusion down draw method, the bottom edge 12b of the sheet of glass 12 would also include the beads formed from engagement by the rollers. The beaded edges 12a, 12b of the sheet of glass 12 may be cut off after thermal processing by the apparatus 10.

[0049] The transport apparatus 28 may move the sheets of glass 12 while holding the clamp assembly 36 by the rod 38. The first pulley apparatus 30 may be located inside the first vertical passage 16. The first pulley apparatus 30 may include a pair of loops 52 that are spaced apart by about the length of the rod 38 and each loop 52 may include a top pulley 54 and a bottom pulley 56. The top pulleys 54 rotate at the same speed and may be operatively coupled with one another. The bottom pulleys 56 also rotate at the same speed, as one another and as the top pulley 54, and may be operatively coupled with one another. Each loop 52 may be formed of a belt wound around the top and bottom pulleys 54, 56 and a set of cups 58 that are rotatably coupled to the belt and are moved around the loop 52. The cups 58 may be configured to accommodate the ends of the rod 38 which may be disposed on the cups 58 by a robotic arm 60 and about which the sheet of glass 12 is suspended. The robotic arm 60 may be located at the bottom of the first vertical passage 16. The cups 58 are moved upward along one side of the loop 52 and are moved downward along another side of the loop 52. The sheets of glass 12 are moved upward in a vertical column in the first vertical passage 16 in a substantially vertical orientation. The bottom pulley 56 should be designed to allow for thermal expansion of the top pulleys 54 and loop 52.

[0050] As shown in FIG. 3, after the cups 58 are moved around the top pulley 54, the rod

38 of the clamp assembly 36 is disposed on the conveyor 32 for movement in the horizontal passage 18. In the present embodiment shown in FIGS. 5-6, the conveyor 32 is a walking beam conveyor that includes a pair of fixed beams 62 and a pair of moving beams 64. As shown in FIGS. 2 and 5-6, the beams 62, 64 extend near the top of the horizontal passage 18. The fixed beams 62 are positioned about the loops 52 so that the ends of the rod 38 are placed on the fixed beams 62 as the cups 58 of the first pulley apparatus 30 move by the fixed beams 62. Each moving beam 64 includes at least two points 66 that are coupled to fixed points 68 on the fixed beam 62 and that rotate in a circle about the fixed points 68 at a constant speed. One cycle of motion by the moving beam 64 advances the rod of the clamp assembly 36 by a set interval along the fixed beam 62 such that the rod 38 is gradually moved from the first end 18a to the second end 18b. The fixed beam 62 and the moving beam 64 may be entirely contained in the horizontal passage 18. Alternatively, the moving beam 64 may penetrate the walls defining the horizontal passage 18 and it may be possible to use bellows 70 (FIG. 2) to provide sealing between the moving beam 64 and the walls 24.

[0051] The second pulley apparatus 34 may be located inside the second vertical passage

20 and may be structurally similar to the first pulley apparatus 30. The second pulley apparatus 34 may include a pair of loops 52 that are spaced apart by about the length of the rod 38 and each loop 52 may include a top pulley 54 and a bottom pulley 56. The top pulleys 54 rotate at the same speed and may be operatively coupled with one another. The bottom pulleys 56 also rotate at the same speed, as one another and as the top pulley 54, and may be operatively coupled with one another. Each loop 52 may be formed of a belt wound around the top and bottom pulleys 54, 56 and a set of cups 58 that are rotatably coupled to the belt and are moved around the loop 52. The cups 58 may be configured to accommodate the ends of the rod 38. The cups 58 are moved upward along one side of the loop 52 and are moved downward along another side of the loop 52.

[0052] The fixed beams 62 are positioned about the second pulley apparatus 34 such that the ends of the rod 38 are picked up by the cups 58 as the cups 58 are moved and the clamp assemblies 36 are moved downward in the second vertical passage 20. A robotic arm 60 may be provided at the bottom of the second vertical passage 20 so that the clamp assemblies 36 can be removed from the cups 58.

[0053] The speeds at which the cups 58 move around the loop 52 may vary. The cups 58 may come to a stop at various points during movement around the loop 52. For example, the cups 58 may come to a full stop when the cups reach the extremities of the loop 52 and the cups 58 may decelerate as the cups 58 move toward the top pulley 54 or the bottom pulley 56 and may accelerate as the cups 58 move away from the top pulley 54 or the bottom pulley 56.

[0054] The above-described configuration of the first vertical passage 16, the horizontal passage 18 and the second vertical passage 20 allows the sheets of glass 12 to maintain a substantially vertical orientation while moving through the heated chamber 14. A large number of sheets of glass 12 can be moved through the chamber 14 to raise an efficiency of the apparatus 10. The sheets of glass 12 can be moved upward in a vertical column substantially enclosed by the first set of heating elements 22 of the first vertical passage 16.

[0055] The heating elements 22 may be controlled so that temperature is gradually increased in the upward direction. For example, the temperature may be increased from room temperature to 350 °C or above as the sheets of glass 12 are moved upward in the first vertical passage 16. As described above, the heating elements 22 in the first vertical passage 16 may be divided into thermal sections such that the intensity of the heating elements 22 in a given thermal section can be controlled as one. Also, the thermal sections may allow power to be differentially applied to enable a desired temperature profile in the first vertical passage 16. [0056] Moreover, in the horizontal passage 18, the sheets of glass 12 may be moved in a horizontal row while the sheets 12 are oriented substantially vertically and substantially enclosed by the second set of heating elements 22. In the horizontal passage 18, the sheets 12 may be heated to a temperature range (e.g., 600-750 °C) and maintained in this temperature range for a sufficient period of time to allow the Active temperature of the glass to be lowered to a desired level. The heating elements 22 in the horizontal passage 18 may be divided into thermal sections such that the intensity of the heating elements 22 in a given thermal section can be controlled as one. Also, the thermal sections may allow power to be differentially applied to enable a desired temperature profile in the horizontal passage 18.

[0057] In the second vertical passage 20, the sheets of glass 12 may be moved downward in a vertical column in which the sheets of glass 12 are substantially vertically oriented and enclosed by the third set of heating elements 22. The sheets of glass 12 may be cooled to a temperature of about 200 °C or less in the second vertical passage 20. The heating elements 22 in the second vertical passage 20 may be divided into sections such that the intensity of the heating elements 22 in a given section can be controlled as one. Also, the thermal sections may allow power to be differentially applied to enable a desired temperature profile in the second vertical passage 20.

[0058] The thermal sections in the first and second vertical passages 16 and 20 may be one or plural, for example four as shown in FIG. 2, each being as long as about the height of a sheet of glass 12 and each corresponding to a discrete temperature range.

[0059] An example operation of the aforementioned apparatus 10 may occur as described in the following. A sheet of glass 12 may be formed through a fusion down draw method and may be transported to the apparatus 10 by the robot arm 60 which may rotate the sheets 90 degrees from a landscape orientation (wherein the beads extend vertically) to a portrait orientation (wherein the beads extend horizontally). The sheet of glass 12 may include beaded edges 12a, 12b which may be pinched by the clamp assemblies 36 to facilitate movement of the sheets 12. The beaded edges would extend at the top and bottom edges 12a, 12b once the sheets of glass 12 are brought to a portrait orientation. A clamp assembly 36 may also be placed on the bottom edge 12b of the sheet of glass 12 to reduce warping. Thereafter, the rod 38 of the clamp assembly 36 is placed on the cups 58 moving about the loop 52 as the cups 58 move past the bottom pulleys 56 of the first pulley apparatus 30. The clamp assembly 36 then moves upward in the first vertical passage 16 while maintaining a substantially vertical orientation. Thus, a plurality of sheets of glass 12 moving through the first vertical passage 16 may move in a vertical column while being heated by the heating elements 22 in the first vertical passage 16 and gradually heated from, for example, room temperature or a temperature above room temperature. Once the cups 58 have moved around the top pulleys 54 of the first pulley apparatus 30, the ends of the rod 38 are caught by the fixed beam 62 such that the rod 38 temporarily rests on the fixed beam 62. Alternatively, it may be possible to configure the transport apparatus 28 such that the ends of the rod 38 are caught by the moving beam 64 or such that the rod 38 temporarily rests on the moving beam 64 as the rod 38 is transferred from the transport apparatus 28. The motion of the moving beam 64 advances the rod 38 by a given distance at along the fixed beam 62 during each cycle. Thus, a plurality of sheets of glass 12 moving through the horizontal passage 18 maintain a substantially vertical orientation and move in a horizontal row while being heated by the heating elements 22 of the horizontal passage 18 at a peak temperature. Once the rods 38 reach the end of the fixed beam 62, the positions of the rods 38 are configured to be picked up by the cups 58 as the cups 58 rotate around the top pulleys 54 of the second pulley apparatus 34. Thereafter, the sheets of glass 12 move downward in the second vertical passage 20 maintaining a substantially vertical orientation. The plurality of sheets 12 thus move in a vertical column while undergoing a controlled cooling by way of the heating elements 22 and being cooled to a temperature lower than the peak temperature. Once the sheets of glass 12 exit the second vertical passage 20, the sheets 12 may be moved and carried by a robotic arm 60 to a site for change of orientation or additional, downstream processing, for example cutting off of the beaded edges 12a, 12b.

[0060] The aforementioned apparatus 10 may allow for thermal processing of the sheets of glass 12 even at spatially restricted manufacturing sites because the footprint of the apparatus 10 can be kept relatively small due to the vertical orientation of the sheets of glass 12 throughout the entire movement inside the chamber 14. The vertical orientation of the sheets of glass 12 also makes it difficult for contaminating particles to be deposited on the surface of the sheets of glass 12 unlike a process involving horizontal orientation of the sheet of glass 12. Additionally, the vertical orientation assists in avoiding slumping, warping, or other sheet-shape change in the sheets as the sheets are heat-treated. Moreover, because the sheets of glass 12 are moved through the chamber 14 while being gripped along the edges 12a or 12b which may subsequently be cut off, the majority of the surfaces of the sheets 12 may be kept untouched and the sheets of glass 12 are less likely to have defects. Further, the sheets 12 may be heated to the soak temperature on their way up the first vertical passage 16 (in which the sheets 12 are heated without other sheets 12 facing their major surface areas), and then held at a constant soak temperature in the horizontal furnace 18 (in which the sheets 12 may be spaced very close to one another as the temperature of their major surfaces does not need to be increased, and then cooled from the soak temperature in the second vertical passage 20 (in which, again, the temperature of the sheets 12 can be changed when the major surface area of the sheets 12 does not have another sheet 12 between itself and the heating element 22). Still further, since the beads are left on the glass for a good gripping contact with the glass, there is less chance for damage and particle generation, as cut edges typically results in glass particle contamination.

[0061] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention. For example, although a walking beam type of mechanism was described for moving the sheets through the horizontal passage, any suitable mechanism, having a gentle smooth moving, operation may be used.