WO2016085725A1

WO2016085725A1 - Apparatus for manufacturing a glass ribbon

Info

Publication number: WO2016085725A1
Application number: PCT/US2015/061245
Authority: WO
Inventors: Tetsuya Furuya; Makoto KAWAHATA
Original assignee: Corning Incorporated
Priority date: 2014-11-24
Filing date: 2015-11-18
Publication date: 2016-06-02
Also published as: TW201623161A; CN204779315U

Abstract

A glass manufacturing apparatus comprising a forming body from which molten glass is drawn to produce a glass ribbon, an enclosure comprising at least a portion that extends below the forming body, and a retractable flow diverter positioned at a predetermined distance from a bottom edge of the forming body. The retractable flow diverter is movable in a direction perpendicular to the flow direction of the glass ribbon and is configured to capture molten glass condensate flowing within the glass manufacturing apparatus.

Description

APPARATUS FOR MANUFACTURING A GLASS RIBBON

[0001] This application claims the benefit of priority under 35 U.S.C. § 1 19 of U.S.

Provisional Application Serial No. 62/083527 filed on November 24^th 2014 the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

Field

[0002] The present disclosure relates generally to an apparatus for drawing a glass ribbon from a molten material, and in particular to a retractable flow diverter configured to prevent errant molten material from fouling downstream components, such as rolls that contact the glass ribbon.

Technical Background

[0003] Downdraw glass making processes for forming glass sheets typically draw a molten material, hereinafter "molten glass", from a forming body in the shape of a ribbon. During this process, molten glass condensate can form in areas below the forming body and undesirably flow onto downstream processing components, such as rolls that contact the glass ribbon. For example, such errant molten glass may become wrapped around the roll, disrupting the draw process. This can further cause disruptions in the manufacturing process, including down-time during which no glass ribbon can be produced, or even necessitating equipment replacement.

SUMMARY

[0004] Molten glass condensate dropping from regions of a glass manufacturing apparatus onto downstream processing equipment, such as rolls, can cause disruptions in the manufacturing process. Such molten glass condensate may ultimately adhere the glass ribbon itself, causing ribbon defects and crackouts. To minimize these disruptions, retractable flow diverters are positioned at a predetermined distance from a bottom edge of a forming body of the glass manufacturing apparatus. [0005] Accordingly, in one embodiment, an apparatus for drawing a glass ribbon is disclosed that includes a forming body from which molten glass is drawn to produce a glass ribbon. The apparatus also includes an enclosure comprising at least a portion that extends below the forming body, the enclosure having at least one inner wall, the inner wall comprising at least a portion that extends below the forming body. The apparatus further includes a retractable flow diverter positioned at a predetermined distance from a bottom edge of the forming body, the retractable flow diverter movable in a direction perpendicular to the flow direction of the glass ribbon from at least a first position to a second position, the retractable flow diverter having a tip portion that is closer to the glass ribbon when the retractable flow diverter is in the second position than when the retractable flow diverter is in the first position. In addition, when molten glass is drawn to produce a glass ribbon and the retractable flow diverter is in the second position, the retractable flow diverter is configured to capture molten glass condensate flowing from the at least one inner wall.

[0006] Additional features and advantages of these and other embodiments 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 as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0007] It is to be understood that both the foregoing general description and the following detailed description present embodiments of the present disclosure, and are intended to provide an overview or framework for understanding the nature and character of the embodiments as claimed. The accompanying drawings are included to provide a further understanding of these and other embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of these and other embodiments, and together with the description serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is an elevational view of an example glass manufacturing apparatus;

[0009] FIG. 2 is a perspective view of an example of a retractable flow diverter of the glass manufacturing apparatus of FIG. 1 ;

[0010] FIG. 3 is a side view of a pair of retractable flow diverters positioned on opposing sides of the glass ribbon, wherein the retractable flow diverters are in a first position; [0011] FIG. 4 is a side view of a pair of retractable flow diverters positioned on opposing sides of the glass ribbon, wherein the retractable flow diverters are in a second position;

[0012] FIG. 5 is a side view of a pair of retractable flow diverters positioned on opposing sides of the glass ribbon, wherein the flow diverters are in a second position and have captured molten glass condensate flowing from an inner wall at an earlier time (Tl);

[0013] FIG. 6 is a side view of a pair of retractable flow diverters positioned on opposing sides of the glass ribbon, wherein the flow diverters are in a second position and have captured molten glass condensate flowing from an inner wall at a later time (T2);

[0014] FIG. 7 is a side view of a pair of retractable flow diverters positioned on opposing sides of the glass ribbon, wherein the flow diverters are returned to a first position having captured molten glass condensate;

[0015] FIG. 8 is a top cutaway view of a pair of retractable flow diverters, wherein one retractable flow diverter has been moved in a direction parallel to an extension direction of a handle on the retractable flow diverter;

[0016] FIG. 9 is an elevational view of an example glass manufacturing apparatus that comprises a plurality of pairs of retractable flow diverters;

[0017] FIG. 10 is a cross-sectional view of an embodiment of a retractable flow diverter cooling mechanism that can be used in one or more embodiments disclosed herein; and

[0018] FIGS. 1 1 A and 1 1 B show s-shaped expansion joints that can be used in one or more locations along the length of retractable flow diverters according to one or more embodiments disclosed herein.

DETAILED DESCRIPTION

[0019] Reference will now be made to embodiments of the present disclosure, 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.

[0020] FIG. 1 illustrates an example fusion-type glass manufacturing apparatus 10 comprising a first enclosure 12, a forming body 14 positioned within the first enclosure and a second enclosure 32 positioned below the first enclosure. Also shown are a pair of rolls 38 positioned below the forming body. Rolls 38 may be positioned, for example, within the second enclosure. Rolls 38 are typically arranged as counter-rotating pairs configured to engage with edge portions of the glass ribbon and typically comprise a body portion coupled to a shaft. While only one pair of rolls 38 is shown in FIG. 1 , it is to be understood that there can be a plurality of pairs of counter-rotating rolls configured to engage with the edge portions of the glass ribbon.

[0021] Forming body 14 may comprise a trough 20 formed in an upper surface of the forming body, and converging forming surfaces 22 located on an exterior of the forming body that join at a lower edge 24, of forming body 14. Molten glass 26 is supplied to and overflows the walls of trough 20. The overflowing molten glass flows over converging forming surfaces 22 as separate streams that join at lower edge 24 to form glass ribbon 28. Glass ribbon 28 flows along plane 50 and is engaged by rolls 38 along edge portions of the glass ribbon and drawn downward in a draw direction 29 to a predetermined thickness. Pairs of rolls may be positioned at different distances from the lower edge. Cooling members 30 may be positioned adjacent the converging forming surfaces and near the lower edge of the forming body to aid in thickness control. On the glass ribbon has reached the predetermined thickness and cooled sufficiently to become an elastic solid, individual glass sheets are subsequently separated from the glass ribbon and provided to downstream processing apparatus that further process the sheets.

[0022] In some instances molten glass may seep from joints between delivery apparatus (e.g. pipes that convey the molten glass to the forming body) and forming body 14. In some instances this seepage, or errant molten glass 55, may fall from regions of the manufacturing apparatus 10 located above rolls 38 and contact the rolls. Molten glass 55 may also condense on the walls of the second enclosure 32. If contact with the rolls occurs, the errant molten glass 55 may stick to and become wrapped about the roll. This can be a particular problem if the location where the errant molten glass adheres coincides with the surface of the roll body portion that engages with the glass ribbon. In extreme cases, a complete disruption of the drawing process can occur where the glass ribbon is no longer guided by the rolls and flows freely from the forming body. In addition, molten glass on rolls and other process components can adhere to the glass sheet, causing ribbon defects and crackouts.

[0023] To minimize these disruptions, a retractable flow diverter is positioned at a predetermined distance from a bottom edge of the forming body 14. For example, as shown in FIG. 1, a pair of retractable flow diverters 40 are positioned on opposing sides of the glass ribbon 28 at a predetermined distance below the forming body 14. In the embodiment of FIG. 1, retractable flow diverters are each housed in a housing 36 that is situated immediately below second enclosure 32 and above a third enclosure 34 region. In exemplary

embodiments housing 36 can be a rectangular-shaped enclosure having an opening along the side of the housing that is closest to glass ribbon 28, thereby allowing retractable flow diverters 40 to move within and out of housing 36. In the embodiment of FIG. 1, the side of the housing 36 that is closest to the glass ribbon 28 is flush with an inner wall of second enclosure 32.

[0024] Housing 36 and retractable flow diverter 40 may comprise a high temperature material capable of withstanding temperatures that can reach 1 100°C or greater in the vicinity of the forming body. For example, at least one of housing 36 and retractable flow diverter 40 may comprise one or more high temperature metal alloys such as Haynes® Alloy No. 214 or Haynes® Alloy No. 230.

[0025] Referring to FIG. 2, retractable flow diverter 40 can comprise a first end, a second end, and a weir 42 extending along the tip portion from the first end to the second end of the retractable flow diverter. In the embodiment of FIG. 2, retractable flow diverter 40 also comprises a first edge region 43 extending from a first end of the weir 42 to a first end of a back region 45 of the retractable flow diverter 40 and a second edge region 44 extending from a second end of the weir 42 to a second end of the back region 45 of the retractable flow diverter 40. Weir 42, first edge region 43, second edge region 44, and back region 45 bound a recessed area 48, wherein the recessed area 48 has a top surface that is lower than the top surfaces of the weir 42, the first edge region 43, the second edge region 44, and the back region 45. Retractable flow diverter further includes a handle 46 that extends in a direction parallel to the extension direction of the weir 42, the handle extending from at least one of the first end and the second end of the retractable flow diverter 40. In the embodiment of FIG. 2, handle 46 extends from and within back region 45.

[0026] The embodiment illustrated in FIG. 2 can further enable capture of molten glass condensate by allowing molten glass to flow into recessed area 48 wherein weir 42, first edge region, 43, second edge region 44, and back region 45 act as barriers to prevent molten glass from flowing or dripping onto downstream processing components, such as rolls, or flowing or dripping onto the glass ribbon.

[0027] Operation of retractable flow diverters will described with reference to FIGS. 3-7. FIG. 3 shows a pair of retractable flow diverters 40 positioned on opposing sides of the glass ribbon 28, wherein each retractable flow diverter is primarily housed in a housing 36 in a first position. FIG. 4 shows the pair of retractable flow diverters 40 in a second position, wherein the retractable flow diverters 40 have been moved in a direction perpendicular to the flow direction of the glass ribbon 28. As can be seen in FIG. 4 as compared to FIG. 3, tip portion of retractable flow diverters 40 is closer to the glass ribbon 28 when the retractable flow diverters 40 are in the second position as compared to the first position.

[0028] Retractable flow diverters 40 can be moveable by one or more of a variety of mechanisms. For example retractable flow diverters 40 can be moveable on tracks or rollers that facilitate movement of the retractable flow diverters between a first position and a second position. Retractable flow diverters 40 may also be moved manually, for example by a manual operator using handle 46 to move retractable flow diverter 40 between a first position and a second position. In addition, retractable flow diverters 40 may be moved via an automated mechanism, such as a motorized mechanism that moves the retractable flow diverter 40 between a first position and a second position. In certain exemplary

embodiments, the automated mechanism can be a component of a control mechanism can be configured to move the retractable flow diverters from a first position to a second position at predetermined time intervals or in response to a feedback or feedforward control algorithm.

[0029] FIG. 5 shows a pair of retractable flow diverters 40 positioned on opposing sides of the glass ribbon 28, wherein the flow diverters are in a second position and have captured molten glass condensate 55 flowing from an inner wall of second enclosure 32 at an earlier time (Tl). FIG. 6 shows the same pair of retractable flow diverters 40 having captured the molten glass condensate 55 at a later time (T2), wherein more of molten glass has flowed into a central portion of the flow diverters, such as in recessed area 48. FIG. 7 shows the same pair of retractable flow diverters 40, wherein the flow diverters are returned to a first position having captured molten glass condensate 55.

[0030] While not limited to any specific distance, the distance between the tip portions of the pair of retractable flow diverters when the retractable flow diverters are in the first position (e.g., as shown in FIG. 3) is at least five times greater, such as at least ten times greater, than the distance between the tip portions of the pair of retractable flow diverters when the retractable flow diverters are in the second position (e.g., as shown in FIG. 4). For example, the distance between the tip portions of the pair of retractable flow diverters when the retractable flow diverters are in the first position can be between five and ten times the distance between the tip portions of the retractable flow diverters when the retractable flow diverters are in the second position. In certain exemplary embodiments, retractable flow diverters can, in the first position, be approximately flush with housing and/or inner wall of enclosure. Allowing a relatively larger distance between flow diverters when the retractable flow diverters are in the first position can minimize the probability of rubicons and back-fill related problems, for example, during flushing of the apparatus while allowing a relatively smaller distance between flow diverters when the flow diverters are in the second position can enable more complete capture of molten glass condensate.

[0031] FIG. 8 shows a top cutaway view of a pair of retractable flow diverters, wherein the retractable flow diverter 40 shown on the right hand side of the figure has been moved in a direction 59 parallel to an extension direction of a handle 46 on the retractable flow diverter. Such movement can allow at least a portion of one or more retractable flow diverters to be positioned outside of an enclosure region of the glass manufacturing apparatus, such as third enclosure region 34. In certain embodiments, the retractable flow diverter can be entirely removable from the apparatus. This can allow for molten glass condensate 55 captured by the retractable flow diverter 40 to be easily and efficiently removed from the retractable flow diverter or for complete replacement of the retractable flow diverter. Retractable flow diverter 40 can then be replaced by a new retractable flow diverter or be repositioned to its original position inside an enclosure region of the glass manufacturing apparatus following removal of molten glass condensate 55 from retractable flow diverter.

[0032] In the embodiment shown in FIG. 8, retractable flow diverters 40 maybe moved manually, for example by a manual operator using handle 46 to move retractable flow diverter 40. In the embodiment shown in FIG. 8, retractable flow diverters 40 may also be moved via an automated mechanism, such as a motorized mechanism.

[0033] While FIG. 8 shows only the retractable flow diverter 40 on the right hand side being moved in a direction 59 parallel to an extension direction of a handle 46 on the retractable flow diverter 40, it is to be understood that both retractable flow diverters 40 can be similarly movable.

[0034] FIG. 9 is an elevational view of an example glass manufacturing apparatus that comprises a plurality of pairs of retractable flow diverters. For example, manufacturing apparatus may comprise at least one pair of retractable flow diverters 40 positioned between forming body and at least one pair of rolls 38. Positioning retractable flow diverters 40 between forming body and rolls 38 enables prevention of molten glass condensate flowing from an inner wall of the apparatus from contacting the roll. Manufacturing apparatus may also comprise at least one pair of retractable flow diverters 40 positioned beneath at least one pair of rolls such as in a muffle region of the apparatus. This can further minimize or prevent undesirable flow of molten glass onto downstream processing equipment. [0035] FIG. 10 shows a cross-sectional view of an embodiment of a cooling mechanism that can be used in one or more embodiments disclosed herein. In the embodiment shown in FIG. 10, retractable flow diverter 40 includes handle 46 and interior cooling channel (e.g., pipe) 60 that can be used to transport a cooling fluid, such as water, from a cooling fluid source (not shown) through cooling channel 60 in the flow direction of arrow 64 and then continuing in the flow direction of arrows 62, eventually flowing into a cooling fluid outlet (not shown). Cooling mechanism can be optionally included in embodiments herein in order to cool one or more retractable flow diverters in order to, for example, mitigate sag and deformation of retractable flow diverters due to the high temperatures inside the glass manufacturing apparatus. Cooling mechanism can also enable substantial cooling of molten glass condensate, enabling more efficient capture of the molten glass by the flow diverters as a result of the increased viscosity of the cooled condensate.

[0036] FIGS. 1 1 A and 1 1 B show s-shaped expansion joints that can be optionally used in one or more locations along the length of retractable flow diverters in order to mitigate deformation of retractable flow diverters due to the thermal expansion of flow diverter materials. Specifically, FIG. 1 1A shows an s-shaped expansion joint when the material of the retractable flow diverter is at a relatively lower temperature (e.g., when a flow diverter has been initially exposed to the interior of the glass manufacturing apparatus) and FIG. 1 IB shows the s-shaped expansion joint of FIG. 1 1A when the material of the retractable flow diverter is at a relatively higher temperature (e.g., when a flow diverter has been exposed to the interior of the glass manufacturing apparatus for a longer amount of time than that shown in FIG. 1 1 A).

[0037] It should be apparent from the preceding that retractable flow diverters 40 may be positioned over any or all rolls used in the drawing of molten glass, and is not limited to a fusion down-draw process as depicted and described herein. For example, retractable flow diverters 40 may be used in slot draw processes, where molten glass is drawn from a slot formed in the lower surface of a forming body and drawn downward therefrom, or in an up- draw process, where molten glass is drawn upward from a pool of molten glass.

[0038] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of these and other embodiments provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. An apparatus for manufacturing a glass ribbon comprising:

a forming body from which molten glass is drawn to produce a glass ribbon;

an enclosure comprising at least a portion that extends below the forming body, the enclosure having at least one inner wall, said inner wall comprising at least a portion that extends below the forming body;

a retractable flow diverter positioned at a predetermined distance from a bottom edge of the forming body, the retractable flow diverter movable in a direction perpendicular to the flow direction of the glass ribbon from at least a first position to a second position, the retractable flow diverter having a tip portion that is closer to the glass ribbon when the retractable flow diverter is in the second position than when the retractable flow diverter is in the first position and, wherein, when molten glass is drawn to produce a glass ribbon and the retractable flow diverter is in the second position, the retractable flow diverter is configured to capture molten glass condensate flowing from the at least one inner wall.

2. The apparatus according to claim 1, wherein the apparatus further comprises a roll configured to engage a first edge portion of the glass ribbon at a predetermined distance from a bottom edge of the forming body, the roll comprising a body portion coupled to a shaft and, wherein, when molten glass is drawn to produce a glass ribbon and the retractable flow diverter is in the second position, the retractable flow diverter is configured to prevent molten glass condensate flowing from the at least one inner wall from contacting the roll.

3. The apparatus according to claim 1, wherein the retractable flow diverter comprises a first end and a second end, a weir extending along the tip portion from the first end to the second end of the retractable flow diverter, a first edge region extending from a first end of the weir to a first end of a back region of the retractable flow diverter, a second edge region extending from a second end of the weir to a second end of the back region of the retractable flow diverter, and a recessed area that is bounded by the weir, the first edge region, the second edge region, and the back region, wherein the recessed area has a top surface that is lower than the top surfaces of the weir, the first edge region, the second edge region, and the back region

4. The apparatus according to claim 3, wherein the retractable flow diverter comprises a handle that extends in a direction parallel to the extension direction of the weir, said handle extending from at least one of the first end and the second end of the retractable flow diverter.

5. The apparatus according to claim 4, wherein the retractable flow diverter is movable in a direction parallel to the extension direction of the handle.

6. The apparatus according to claim 5, wherein the retractable flow diverter is removable from the apparatus.

7. The apparatus according to claim 1, wherein the apparatus comprises a pair of retractable flow diverters positioned on opposing sides of the glass ribbon.

8. The apparatus according to claim 7, wherein the distance between the tip portions of the pair of retractable flow diverters when the retractable flow diverters are in the first position is at least five times greater than the distance between the tip portions of the pair of retractable flow diverters when the retractable flow diverters are in the second position.

9. The apparatus according to claim 1 , wherein the apparatus comprises a plurality of pairs of retractable flow diverters, wherein each pair of retractable flow diverters is positioned on opposing sides of the glass ribbon.

10. The apparatus according to claim 1 , wherein the retractable flow diverter is manually movable from the first position to the second position.

1 1. The apparatus according to claim 1 , wherein the retractable flow diverter is movable from the first position to the second position via an automated control mechanism.