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Title:
GLASS FORMING APPARATUSES WITH MOVEABLE END BLOCK ASSEMBLIES
Document Type and Number:
WIPO Patent Application WO/2018/232092
Kind Code:
A2
Abstract:
A glass forming apparatus including a forming body including first and second forming surfaces. An end block assembly includes an end plate and a moveable support apparatus located on the end plate. The moveable support apparatus includes first and second plates that rest on the end plate. The first plate comprising a front edge that faces the forming body of the glass forming apparatus and a rear edge that faces away from the forming body. The second plate includes a front edge that faces the forming body and a rear edge that faces away from the forming body. One of the first second plates includes a rolling element track that receives ends of a plurality of rolling elements located between the first and second plates.

Inventors:
JUN SEGI (KR)
REGULA ADAM SCOTT (US)
SAKAMOTO SHINYA (JP)
Application Number:
PCT/US2018/037500
Publication Date:
December 20, 2018
Filing Date:
June 14, 2018
Export Citation:
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Assignee:
CORNING INC (US)
CORNING PREC MATERIALS CO LTD (KR)
International Classes:
C03B17/06
Attorney, Agent or Firm:
ABLE, Kevin M (US)
Download PDF:
Claims:
What is claimed is:

1. A glass forming apparatus comprising:

a forming body comprising a first forming surface and a second forming surface; an end block assembly comprising:

an end plate; and

a moveable support apparatus located on the end plate, the moveable support apparatus comprising:

a first plate and a second plate that rest on the end plate, the first plate comprising a front edge that faces the forming body of the glass forming apparatus and a rear edge that faces away from the forming body, the second plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and

a plurality of rolling elements located between the first plate and the second plate; and

wherein one of the first plate and the second plate comprises a rolling element track extending between the front edge and the rear edge of the at least one of the first plate and the second plate that receives ends of the plurality of rolling elements.

2. The glass forming apparatus of claim 1 , wherein the second plate is a top plate that comprises a side wall that extends between the front edge and the rear edge of the top plate, the side wall comprising the rolling element track.

3. The glass forming apparatus of claim 2, further comprising a retaining stop that is located in the rolling element track.

4. The glass forming apparatus of claim 2, wherein the side wall includes a retaining flange that extends beneath the rolling element track.

5. The glass forming apparatus of claim 2, wherein the side wall is a first side wall and the rolling element track is a first rolling element track, the top plate including a second side wall that extends between the front edge and the rear edge of the top plate, the second side wall including a second rolling element track that is configured to receive opposite ends of the plurality of rolling elements.

6. The glass forming apparatus of claim 5, further comprising a retaining stop that is located in the second rolling element track.

7. The glass forming apparatus of claim 5, wherein the second side wall includes a retaining flange that extends beneath the second rolling element track.

8. The glass forming apparatus of claim 1, wherein the first plate is a bottom plate that comprises a retaining lip that extends along the rear edge of the bottom plate.

9. The glass forming apparatus of claim 8, wherein the retaining lip is integrally or monolithically formed with the bottom plate.

10. The glass forming apparatus of claim 8, further comprising a catcher tray that is located at the front edge of the bottom plate, the catcher tray configured to receive one or more of the plurality of rolling elements falling from the front edge of the bottom plate.

11. A glass forming apparatus comprising:

a forming body comprising a first forming surface and a second forming surface; an end block assembly comprising:

an end block engaged with an end face of the forming body;

an end plate located beneath the end block and supporting the end block vertically; and

a moveable support apparatus located between the end block and the end plate, the moveable support apparatus comprising:

a bottom plate that rests on the end plate, the bottom plate comprising a front edge that faces the forming body of the glass forming apparatus and a rear edge that faces away from the forming body; a top plate upon which the end block rests, the top plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and

moveable elements located between the bottom plate and the top plate; and wherein the bottom plate comprises a retaining lip located at the rear edge of the bottom plate and the top plate comprises a retaining stop located at the front edge of the top plate.

12. The glass forming apparatus of claim 11, wherein the moveable elements comprise rolling elements.

13. The glass forming apparatus of claim 12, further comprising a rolling element track extending between the front edge and the rear edge of the top plate that is configured to receive ends of the plurality of rolling elements.

14. The glass forming apparatus of claim 13, wherein the top plate comprises a side wall that extends between the front edge and the rear edge of the top plate, the side wall comprising the rolling element track.

15. The glass forming apparatus of claim 14, wherein the retaining stop is located in the rolling element track.

16. The glass forming apparatus of claim 14, wherein the side wall includes a retaining flange that extends beneath the rolling element track.

17. The glass forming apparatus of claim 14, wherein the side wall is a first side wall and the rolling element track is a first rolling element track, the top plate including a second side wall that extends between the front edge and the rear edge of the top plate, the second side wall including a second rolling element track that is configured to receive opposite ends of the plurality of rolling elements.

18. The glass forming apparatus of claim 17, further comprising a second retaining stop that is located in the second rolling element track.

19. The glass forming apparatus of claim 17, wherein the second side wall includes a retaining flange that extends beneath the second rolling element track.

20. The glass forming apparatus of claim 1 1 , wherein the retaining lip is integrally or monolithically formed with the bottom plate.

21. The glass forming apparatus of claim 1 1 , further comprising a catcher tray that is located at the front edge of the bottom plate, the catcher tray configured to receive one or more of the plurality of rolling elements falling from the front edge of the bottom plate.

22. A moveable support apparatus configured to be located on an end plate of an end block assembly of a glass forming apparatus, the moveable support apparatus comprising: a bottom plate that rests on the end plate, the bottom plate comprising a front edge that faces a forming body of the glass forming apparatus and a rear edge that faces away from the forming body;

a top plate that rests on the bottom plate, the top plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and

a plurality of rolling elements located between the bottom plate and the top plate; wherein the top plate comprises a rolling element track extending between the front edge and the rear edge of the top plate that is configured to receive ends of the plurality of rolling elements.

23. The moveable support apparatus of claim 22, wherein the top plate comprises a side wall that extends between the front edge and the rear edge of the top plate, the side wall comprising the rolling element track.

24. The moveable support apparatus of claim 23, further comprising a retaining stop that is located in the rolling element track.

25. The moveable support apparatus of claim 23, wherein the side wall includes a retaining flange that extends beneath the rolling element track.

26. The moveable support apparatus of claim 23, wherein the side wall is a first side wall and the rolling element track is a first rolling element track, the top plate including a second side wall that extends between the front edge and the rear edge of the top plate, the second side wall including a second rolling element track that is configured to receive opposite ends of the plurality of rolling elements.

27. The moveable support apparatus of claim 26, further comprising a retaining stop that is located in the second rolling element track.

28. The moveable support apparatus of claim 26, wherein the second side wall includes a retaining flange that extends beneath the second rolling element track.

29. The moveable support apparatus of claim 22, wherein the bottom plate comprises a retaining lip that extends along the rear edge of the bottom plate.

30. The moveable support apparatus of claim 29, wherein the retaining lip is integrally or monolithically formed with the bottom plate.

31. The moveable support apparatus of claim 22, further comprising a catcher tray that is located at the front edge of the bottom plate, the catcher tray configured to receive one or more of the plurality of rolling elements falling from the front edge of the bottom plate.

32. The moveable support apparatus of claim 22, further comprising a removable spacer between the front edge of the bottom plate and at least one of the plurality of rolling elements.

Description:
GLASS FORMING APPARATUSES WITH MOVEABLE END BLOCK ASSEMBLIES

Cross-Reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 62/519,507 filed on June 14, 2017 the contents of which are relied upon and incorporated herein by reference in their entirety as if fully set forth below.

BACKGROUND

Field

[0002] The present specification generally relates to glass forming apparatuses and, more specifically, to glass forming apparatuses with moveable end block assemblies.

Technical Background

[0003] The fusion process is one technique for forming glass ribbons. Compared to other processes for forming glass ribbons, such as the float and slot-draw processes, the fusion process produces glass ribbons with a relatively low amount of defects and with surfaces having superior flatness. As a result, the fusion process is widely employed for the production of glass substrates that are used in the manufacture of LED and LCD displays and other substrates that require superior flatness and smoothness.

[0004] In the fusion process, molten glass is fed into a forming body that includes forming surfaces which converge at a bottom edge. The molten glass evenly flows over the forming surfaces of the forming body and forms a ribbon of flat glass with pristine surfaces that is drawn from the bottom edge of the forming body.

[0005] The forming body is generally made of refractory materials, such as refractory ceramics, which are better able to withstand the relatively high temperatures of the fusion process. Due to high operating temperature and the gravitational load caused by the forming body itself, the forming body may sag over time. This can cause the flow rate of the molten glass to change along the forming body and can affect final glass quality. At the present time horizontal compression force is used to control sag of the forming body. A challenge in applying the horizontal compression force is that, once the compression force is applied, the forming body may expand due to the operating temperatures and contract during periods of cool down and bottom edge contraction.

[0006] Accordingly, a need exists to apply a horizontal compression force at an end of the forming body while allowing for expansion and contraction of the forming body.

SUMMARY

[0007] According to one embodiment, a glass forming apparatus comprises: a forming body comprising a first forming surface and a second forming surface; an end block assembly comprising: an end plate; and a moveable support apparatus located on the end plate, the moveable support apparatus comprising: a first plate and a second plate that rest on the end plate, the first plate comprising a front edge that faces the forming body of the glass forming apparatus and a rear edge that faces away from the forming body, the second plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and a plurality of rolling elements located between the first plate and the second plate; and wherein one of the first plate and the second plate comprises a rolling element track extending between the front edge and the rear edge of the at least one of the first plate and the second plate that receives ends of the plurality of rolling elements.

[0008] In another embodiment, a glass forming apparatus comprises: a forming body comprising a first forming surface and a second forming surface; an end block assembly comprising: an end block engaged with an end face of the forming body; an end plate located beneath the end block and supporting the end block vertically; and a moveable support apparatus located between the end block and the end plate, the moveable support apparatus comprising: a bottom plate that rests on the end plate, the bottom plate comprising a front edge that faces the forming body of the glass forming apparatus and a rear edge that faces away from the forming body; a top plate upon which the end block rests, the top plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and a plurality of rolling elements located between the bottom plate and the top plate; and wherein the bottom plate comprises a retaining lip located at the rear edge of the bottom plate and the top plate comprises a retaining stop located at the front edge of the top plate. [0009] In another embodiment, a moveable support apparatus is configured to be located between an end block and an end plate of an end block assembly of a glass forming apparatus, the moveable support apparatus comprising: a bottom plate that rests on the end plate, the bottom plate comprising a front edge that faces a forming body of the glass forming apparatus and a rear edge that faces away from the forming body; a top plate upon which the end block rests, the top plate comprising a front edge that faces the forming body and a rear edge that faces away from the forming body; and a plurality of rolling elements located between the bottom plate and the top plate; wherein the top plate comprises a rolling element track extending between the front edge and the rear edge of the top plate that is configured to receive ends of the plurality of rolling elements.

[0010] Additional features and advantages of the glass forming apparatuses described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0011] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 schematically depicts one embodiment of a glass forming apparatus according to one or more embodiments shown and described herein;

[0013] FIG. 2 schematically depicts a perspective view of a forming body supported by edge block assemblies according to one or more embodiments shown and described herein;

[0014] FIG. 3 schematically depicts a cross section of the forming body along line 3-3 of FIG. 2 according to one or more embodiments described herein; [0015] FIG. 4 schematically depicts a detail view of the glass forming apparatus of FIG. 1 showing an edge block assembly including a moveable support apparatus according to one or more embodiments shown and described herein;

[0016] FIG. 5 depicts a bottom plate of the moveable support apparatus of FIG. 4 according to one or more embodiments shown and described herein;

[0017] FIG. 6 depicts a top plate of the moveable support apparatus of FIG. 4 according to one or more embodiments shown and described herein;

[0018] FIG. 7 schematically depicts operation of the moveable support apparatus of FIG. 4 according to one or more embodiments shown and described herein;

[0019] FIG. 8 schematically depicts operation of the moveable support apparatus of FIG. 4 according to one or more embodiments shown and described herein;

[0020] FIG. 9 depicts another embodiment of a top plate for use with a moveable support apparatus according to one or more embodiments shown and described herein;

[0021] FIG. 10 schematically depicts another moveable support apparatus according to one or more embodiment shown and described herein;

[0022] FIG. 11 schematically depicts another embodiment of a moveable support apparatus according to one or more embodiments shown and described herein;

[0023] FIG. 12 schematically depicts another embodiment of a moveable support apparatus according to one or more embodiments shown and described herein; and

[0024] FIG. 13 schematically depicts low-friction sliding plates for use with a moveable support apparatus according to one or more embodiment shown and described herein.

DETAILED DESCRIPTION

[0025] Reference will now be made in detail to embodiments of glass forming apparatuses, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The glass forming apparatus may include a forming body comprising a first forming surface and a second forming surface. The first forming surface and the second forming surface converge at a bottom edge. The forming body is supported at opposite ends by end blocks. The end blocks are located at opposite ends of the forming body, beneath overhang portions of the forming body to support the forming body vertically. The end blocks may also be used to apply a horizontal compression force against the ends of the forming body to inhibit or control sag at the bottom edge. A compression apparatus can apply the horizontal compression force to one of the end blocks which transfers the compression force to the end of the forming body. A moveable support apparatus supports the end block such that the end block can move linearly in the horizontal direction to apply the horizontal compression force to the end of the forming block. Various embodiments of the moveable support apparatus and methods for moveably supporting end blocks of glass forming apparatuses will be described in further detail herein with specific reference to the appended drawings.

[0026] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0027] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0028] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0029] Referring to FIG. 1, a glass forming apparatus 10 for making glass articles, such as a glass ribbon 12, is schematically depicted. The glass forming apparatus 10 may generally include a melting vessel 15 configured to receive batch material 16 from a storage bin 18. The batch material 16 can be introduced to the melting vessel 15 by a batch delivery device 20 powered by a motor 22. An optional controller 24 may be provided to activate the motor 22 and a molten glass level probe 28 can be used to measure the glass melt level within a standpipe 30 and communicate the measured information to the controller 24.

[0030] The glass forming apparatus 10 can also include a fining vessel 38, such as a fining tube, coupled to the melting vessel 15 by way of a first connecting tube 36. A mixing vessel 42 is coupled to the fining vessel 38 with a second connecting tube 40. A delivery vessel 46 is coupled to the mixing vessel 42 with a delivery conduit 44. As further illustrated, a downcomer 48 is positioned to deliver glass melt from the delivery vessel 46 to an inlet 50 of a forming body 60. In the embodiments shown and described herein, the forming body 60 is a fusion-forming vessel.

[0031] The melting vessel 15 is typically made from a refractory material, such as refractory (e.g., ceramic) brick. The glass forming apparatus 10 may further include components that are typically made from electrically conductive refractory metals such as, for example, platinum or platinum-containing metals such as platinum-rhodium, platinum- iridium and combinations thereof. Such refractory metals may also include molybdenum, palladium, rhenium, tantalum, titanium, tungsten, ruthenium, osmium, zirconium, and alloys thereof and/or zirconium dioxide. The platinum-containing components can include one or more of the first connecting tube 36, the fining vessel 38, the second connecting tube 40, the standpipe 30, the mixing vessel 42, the delivery conduit 44, the delivery vessel 46, the downcomer 48 and the inlet 50.

[0032] Referring now to FIGS. 2 and 3, the forming body 60 generally includes a trough 61, a first forming surface 62, and a second forming surface 64. The trough 61 is located in an upper portion 65 of the forming body 60. The first forming surface 62 and the second forming surface 64 extend from the upper portion 65 of the forming body 60 in a downstream direction (i.e., the -z direction of the coordinate axes depicted in the figures) and converge towards one another, j oining at a bottom edge 70. The bottom edge 70 forms the lower edge of the forming body 60. Accordingly, it should be understood that the first forming surface 62 and the second forming surface 64 form an inverted isosceles (or equilateral) triangle extending from the upper portion 65 of the forming body 60 with the bottom edge 70 forming the lower-most vertex of the triangle in the downstream direction. A draw plane 72 generally bisects an angle Θ between the first forming surface 62 and the second forming surface 64, extending through the bottom edge 70 in the +/- y directions.

[0033] Referring now to FIGS. 1 -3, in operation, batch material 16, specifically batch material for forming glass, is fed from the storage bin 18 into the melting vessel 15 with the batch delivery device 20. The batch material 16 is melted into molten glass in the melting vessel 15. The molten glass passes from the melting vessel 15 into the fining vessel 38 through the first connecting tube 36. Dissolved gasses, which may result in glass defects, are removed from the molten glass in the fining vessel 38. The molten glass then passes from the fining vessel 38 into the mixing vessel 42 through the second connecting tube 40. The mixing vessel 42 homogenizes the molten glass, such as by stirring, and the homogenized molten glass passes through the delivery conduit 44 to the delivery vessel 46. The delivery vessel 46 discharges the homogenized molten glass through downcomer 48 and into the inlet 50 which, in turn, passes the homogenized molten glass into the trough 61 of the forming body 60.

[0034] The homogenized molten glass fills the trough 61 of the forming body 60 and ultimately overflows, flowing over the upper portion 65 of the forming body 60 and in the downstream direction. The homogenized molten glass flows from the upper portion of the forming body 60 and onto the first forming surface 62 and the second forming surface 64. Streams of homogenized molten glass flowing over the first forming surface 62 and the second forming surface 64 j oin and fuse together (hence "fusion forming") at the bottom edge 70, forming a glass ribbon 12 which is drawn on the draw plane 72 in the downstream direction by pulling rolls (not shown). The glass ribbon 12 may be further processed downstream of the forming body 60 such as by segmenting the glass ribbon 12 into discrete glass sheets, rolling the glass ribbon 12 upon itself, and/or applying one or more coatings to the glass ribbon 12. [0035] The forming body 60 is typically formed from refractory ceramic materials which are chemically compatible with the molten glass and which are capable of withstanding the high temperatures associated with the fusion forming process. Typical materials from which the forming body is formed include, without limitation, zircon and/or alumina based refractory ceramics. Given the combined mass of the forming body 60 and the molten glass, along with the elevated temperatures of the fusion forming process, the forming body 60 tends to sag in the downstream direction along its length L due to material creep. This sag is most pronounced at the unsupported midpoint of the length L of the forming body 60.

[0036] The sag in the forming body 60 can cause the homogenized molten glass flowing over the forming surfaces 62, 64 to redistribute, creating a non-uniform flow of molten glass over the forming surfaces 62, 64 which results in changes to the dimensional attributes of the resultant glass ribbon 12. For example, a thickness of the glass ribbon 12 may increase proximate the center of the glass ribbon due to sag. In addition, the redistribution of the molten glass flow towards the center of the forming surfaces 62, 64 along the length L due to sag causes a decrease in glass flow proximate the ends of the forming body 60 resulting in non-uniformity in the dimension of the glass ribbon 12 in the +/- x direction of the coordinate axes depicted in the figures.

[0037] The embodiments of the glass forming apparatus 10 and forming bodies 60 described herein mitigate sag in the forming body 60, reducing stress on the forming body and stabilizing the dimensional characteristics of the glass ribbon 12.

[0038] Referring to FIG. 2, the glass forming apparatus 10 includes a pair of end block assemblies 100 and 102 that can be used to apply a horizontal compression force to the forming body 60 in the +/- y directions. In embodiments described herein, each end block assembly 100 and 102 includes an end block 104 and 106 engaged with end faces 108 and 1 10 of the forming body 60. The end blocks 104, 106 may be positioned on respective end plates 1 12 and 1 14 that are statically affixed to ground such that the end blocks 104 and 106 are supported in the +z direction.

[0039] In embodiments, the end blocks 104 and 106 and end plates 1 12 and 1 14 may be formed from refractory ceramic materials suitable for withstanding the relatively high temperatures of the fusion forming process. Suitable materials include, without limitation, zircon, alumina, silicon carbide, and/or xenotime. Alternatively, the end blocks may be formed from alloys suitable for use at elevated temperatures, such as cobalt-based and/or nickel-based alloys.

[0040] One or both of the end blocks 104 and 106 can be biased towards one another such that the end blocks 104 and 106 impart a compression force F c to the forming body 60 in a direction parallel to a length L of the forming body 60. That is, the compression force F c is generally parallel to the +/- x direction of the coordinate axes. In embodiments, the compression force F c is applied to the end faces 108 and 1 10 at or below the centroid of mass of the forming body 60 such that the compression force F c acts directly on or adjacent to the bottom edge 70 of the forming body 60. In some embodiments, one of the end blocks (e.g., end block 106) may be fixed to apply the compression force F c in reaction to the compression force F c applied by the other end block (e.g., end block 104).

[0041] The compression force F c applied at the end faces 108 and 1 10 of the forming body 60 creates a bending moment in the upstream direction at the midpoint of the forming body 60 along the length L. This bending moment counteracts sag at the bottom edge 70 of the forming body 60, mitigating dimensional variations in the glass ribbon 12 formed with the forming body 60.

[0042] FIG. 4 illustrates the end block assembly 100 of the glass forming apparatus 10 in greater detail. The end block assembly 100 includes the moveable end block 104 and the end plate 1 12 that is fixed relative to the end block 102. A compression system 120 may be used to apply the compression force F c to the end block 102 using a back up block 122 engaged with the end block 104. A moveable support apparatus 124 is located between the end block 104 and the end plate 112. The moveable support apparatus 124 includes a top plate 126 upon which the end block 104 rests and a bottom plate 128 that rests on the end plate 112. A plurality of rolling elements 130 may be located between the top plate 126 and the bottom plate 128 to facilitate movement of the top plate 126 relative to the bottom plate 128. Movement of the top plate 126 relative to the bottom plate 128 also allows horizontal movement of the end block 104 relative to the end plate 1 12, which can be desired, for example, to apply the horizontal compression force F c and also to accommodate expansion and retraction of the forming body 60 in the horizontal direction during heating and cooling conditions. For example, forming body 60 expansions and contractions of 5 cm or more in the horizontal +/- x direction may be realized.

[0043] The rolling elements 130 may be provided to facilitate movement of the top plate 126 relative to the bottom plate 128. The rolling elements 130 may be, for example, cylindrical rods. As the top plate 126 moves horizontally relative to the bottom plate 128, the rolling elements 130 move relative to the bottom plate 128. In this regard, it is desirable to constrain movement of the rolling elements 130 to at least one of the opposite edges 132 and 134 of the bottom plate 128, for example, to prevent the rolling elements 130 from falling out of the moveable support apparatus 124 and toward the draw plane of the glass.

[0044] Referring to FIG. 5, the bottom plate 128 is illustrated in isolation and includes the rear edge 132 that faces away from the forming body 60, the front edge 134 that faces toward the forming body 60 and side edges 136 and 138 that extend between the rear edge 132 and the front edge 134. A retaining lip 140 is located along the rear edge 132 and extends out of a plane of rolling surface 142. In the illustrated example, the retaining lip 140 extends continuously along an entire length of the rear edge 132. In other embodiments, the retaining lip may extend over only a portion of the rear edge 132 and/or there may be multiple, spaced apart retaining lips located along the rear edge 132. The retaining lip 140 may or may not be an integral or monolithic part of the bottom plate 128. In the illustrated embodiment, the retaining lip 140 is monolithically formed as part of the bottom plate 128; however, the retaining lip 140 may be integrally formed and attached along rear edge 132.

[0045] As can be appreciated, the retaining lip 140 serves as a back stop to inhibit movement of the rolling elements 130 beyond the rear edge 132 of the bottom plate 128. Referring now to FIG. 6, the top plate 126 is illustrated in isolation and includes a front edge 144 that faces toward the forming body 60, a rear edge 146 that faces away from the forming body 60 and side edges 148 and 150 that extend between the front edge 144 and the rear edge 146. Side walls 152 and 154 extend along the side edges 148 and 150. The side walls 152 and 154 may extend integrally or monolithically from a plane of rolling surface 156. Each side wall 152 and 154 may provide a rolling element track 158 and 160 with a retaining flange 162 that is sized to extend underneath an end of the rolling elements 130. The rolling element track 158 and 160 may extend the entire lengths of the side edges 148 and 150. [0046] Retaining stops 164 and 166 are provided in the rolling element tracks 158 and 160 at the front edge 144. The retaining stops 164 and 166 may be monolithically formed with the side walls 152 and 154 or the retaining stops 164 and 166 may be formed separately and then attached integrally within the rolling element tracks 158 and 160 of the side walls 152 and 154. The retaining stops 164 and 166 block the rolling element tracks 158 and 160 at the front edge 144 of the top plate 126.

[0047] FIGS. 7 and 8 illustrate the moveable support apparatus 124 in operation on the end plate 1 12. Referring first to FIG. 7, a first extended position of the top plate 126 is shown where the top plate 126 is moved a distance di beyond the front edge 134 of the bottom plate 128. Ends 170 of the rolling elements 130 are received within the rolling element tracks 158 and 160 and the rolling elements 130 roll along the rolling surface 142 of the bottom plate 128 and the rolling surface 156 of the top plate 126 to facilitate horizontal movement of the end block 104 relative to the end plate 1 12.

[0048] Referring to FIG. 8, a second extended position of the top plate 126 is shown where the top plate 126 is moved a farther distance d2 beyond the front edge 134 of the bottom plate 128. The top plate 126 is moved the distance d2 such that some of the rolling elements 130 travel beyond the front edge 134 of the bottom plate 128. As described above, the rolling element tracks 158 and 160 are formed using the retaining flange 162. As can be seen, the retaining flanges 162 are located below the rolling surface 142 of the bottom plate 128 and do not engage the rolling elements 130 unless the rolling elements 130 travel beyond the front edge 134 of the bottom plate 128. The retaining flanges 162 provide support surfaces for the ends 170 of the rolling elements 130 so that the rolling elements 130 do not fall vertically from the rolling element tracks 158 and 160 without the bottom plate 128 supporting the rolling elements 130. Further, the retaining stops 164 and 166 are provided in the rolling element tracks 158 and 160 to prevent the rolling elements 130 from rolling by the front edge 144 of the top plate 126 thereby retaining the rolling elements 130 between the rolling element tracks 158 and 160, even without the presence of the bottom plate 128.

[0049] FIG. 9 illustrates another embodiment of a top plate 176 in isolation and includes a front edge 178 that faces toward the forming body 60, a rear edge 180 that faces away from the forming body 60 and side edges 182 and 184 that extend between the front edge 178 and the rear edge 180. Side walls 186 and 188 extend along the side edges 182 and 184. Each side wall 186 and 188 provides a rolling element track 190 and 192 with a retaining flange 194 that is sized to receive an end of the rolling elements 130 in a fashion similar to that described above.

[0050] In this embodiment, retaining stops are not provided to fill the rolling element tracks 190 and 192. Instead, a retaining stop 196 is provided as a retaining lip that extends along the front edge 178 of the top plate 176 and out of a plane formed by rolling surface 198. In the illustrated example, the retaining stop 196 extends continuously along only a portion of a length of the front edge 178, leaving open regions 200 and 202 at opposite ends 204 and 206 of the retaining stop 196. These open regions 200 and 202 can provide access to the side walls 186 and 188 for forming the rolling element tracks 190 and 192. In other embodiments, there may be multiple, spaced apart retaining stops located along the front edge 178. The retaining stop 196 may or may not be a monolithic part of the top plate 176. In the illustrated embodiment, the retaining stop 196 is part of the top plate 176 as a monolithic structure.

[0051] Referring to FIG. 10, in another embodiment, a multi-level moveable support apparatus 210 may be provided. In this embodiment, the moveable support apparatus 210 includes a bottom plate 212, an intermediate top plate 214 and a top plate 216 with a plurality of rolling elements 218 between the bottom plate 212 and the intermediate top plate 214 and the intermediate top plate 214 and the top plate 216. Retaining lips 220 and 222 are provided to prevent movement of the plurality of rolling elements 218 from moving beyond rear edges 224 and 226 of the intermediate top plate 214 and top plate 216. Retaining stops 225 and 227 are also provided along front edges 228 and 229 to prevent movement of the plurality of rolling elements 218 from moving beyond the front edges 228 and 229.

[0052] FIG. 1 1 illustrates another embodiment of a moveable support apparatus 230 that includes a catcher tray 232 that is provided at a front edge 234 of a bottom plate 236. The catcher tray 232 may be connected to the bottom plate 236 and includes an elongated holding volume 238 that is used to receive and retain rolling elements 240 that fall from the front edge 234 of the bottom plate 236. The catcher tray 232 may be open-ended and facing toward a space 246 between the bottom plate 236 and top plate 244. A front wall 248 of the catcher tray 232 may extend vertically upward beyond the bottom plate 236 to provide a backstop for the rolling elements 240 as they pass the front edge 234 of the bottom plate 236 to guide the rolling elements 240 into the holding volume 238. A height and volume of the catcher tray 232 may be selected based upon a preselected travel distance of the top plate 244 during operation in order to be sized to capture a preselected number of rolling elements 240. As shown, the catcher tray 232 may be sized to stack the rolling elements 240 in a single column; however, any suitable volume shape may be used for the catcher tray 232. The catcher tray 232 may be used, for example, in addition to or in the absence of a retaining stop located at a front edge 242 of the top plate 244.

[0053] Referring to FIG. 12, in another embodiment, a moveable support apparatus 250 may utilize removable spacers 252a, 252b and 252c that can maintain an initial spacing and position of rolling elements 254 until operation of the glass forming apparatus. For example, the removable spacers 252a, 252b and 252c may be formed of a material (e.g., paper) that can bum or otherwise disintegrate under glass forming operating temperatures to then allow the rolling elements 254 to roll and providing an initial spacing that reduces a possibility that rolling elements 254 will travel beyond front and/or rear edges 256 and 258 of bottom plate 260.

[0054] Referring briefly to FIG. 13, while rolling elements are discussed above for use with the moveable support apparatuses, other moveable elements may be used, such as low- friction contact plates 260 and 262. As an example, a low-friction coating, such as a dry lubricant (e.g., graphite) may be used to facilitate sliding between the contact plates 260 and 262.

[0055] Components of the moveable support apparatuses described above may be made of any suitable materials including refractory ceramic materials suitable for withstanding the relatively high temperatures of the fusion forming process. Suitable materials include, without limitation, zircon, alumina, silicon carbide, and/or xenotime. Components may be formed from alloys suitable for use at elevated temperatures, such as cobalt-based and/or nickel-based alloys.

[0056] Based on the foregoing, it should now be understood that the above-described moveable support apparatuses facilitate horizontal movement of end blocks toward and away from their associated forming bodies relative to end plates. The moveable support apparatuses are provided with rolling element retaining features that inhibit escape of rolling elements during operation, while providing freedom of movement of top plates of the moveable support apparatuses relative to bottom plates.

[0057] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.