WO2016196534A1

WO2016196534A1 - Glass manufacturing apparatus and method with flow through capability

Info

Publication number: WO2016196534A1
Application number: PCT/US2016/035136
Authority: WO
Inventors: William Anthony Whedon
Original assignee: Corning Incorporated
Priority date: 2015-06-04
Filing date: 2016-06-01
Publication date: 2016-12-08
Also published as: CN107683264A; KR20180006458A; TW201710195A; JP2018527272A

Abstract

A glass forming apparatus and method include a glass forming device having an inlet end and a compression end and a trough extending between the inlet end and the compression end. The glass forming device has first and second sides that each extend from weirs on each side of the trough to a root of the glass forming device in the vertical direction. The trough has a depth that decreases between the inlet end and the compression end and the glass forming device further includes a slot that extends along at least a length of the trough in the horizontal direction and extends from the trough to the root of the glass forming device in the vertical direction.

Description

GLASS MANUFACTURING APPARATUS AND METHOD WITH FLOW THROUGH

CAPABILITY

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

Provisional Application Serial No. 62/170,873 filed on June 4^th 2015, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND Field

[0002] The present disclosure relates generally to a glass manufacturing apparatus and method and more specifically to a glass manufacturing apparatus with flow through capability.

Technical Background

[0003] Methods for the manufacture of glass materials, such as flat panel glass for display applications, including LCD televisions and handheld electronic devices, include the fusion draw method wherein molten glass flows over opposing sides of a glass forming device and then rejoins to form a glass sheet below the bottom, or root, of the device. Such methods can enable the production of relatively thin, flat glass sheets with high surface quality, which are desirable characteristics of glass intended for use in display applications.

[0004] In such manufacturing processes, there is a continual desire to increase molten glass flow rates. However, increased flow rates can result in several technical challenges with respect to the glass forming device. Such technical challenges can include, for example, a glass forming device that is subject to increased deformation over time as a result of increasing the cross section of the glass forming device and/or increasing the operation temperature of the molten glass in order to achieve higher flow rates. Increasing the operation temperature may also result in increased erosion or chemical attack of the glass forming device. Accordingly, it would be desirable to achieve higher glass flow rates while mitigating these potentially undesirable effects.

SUMMARY

[0005] Disclosed herein is an apparatus for producing a glass article. The apparatus includes a glass forming device, which includes an inlet end and a compression end and a l trough extending between the inlet end and the compression end. The glass forming device also includes a first side and a second side that each extend from the inlet end to the compression end in the horizontal direction. The first side extends from a first weir on a first side of the trough to a root of the glass forming device in the vertical direction and the second side extends from a second weir on a second side of the trough to the root of the glass forming device in the vertical direction. The trough has a depth that decreases between the inlet end and the compression end. The glass forming device further includes a slot that extends along at least a length of the trough in the horizontal direction and extends from the trough to the root of the glass forming device in the vertical direction.

[0006] Also disclosed herein is a method of producing a glass article. The method includes introducing molten glass to a glass forming device. The glass forming device includes an inlet end and a compression end and a trough extending between the inlet end and the compression end. The glass forming device also includes a first side and a second side that each extend from the inlet end to the compression end in the horizontal direction. The first side extends from a first weir on a first side of the trough to a root of the glass forming device in the vertical direction and the second side extends from a second weir on a second side of the trough to the root of the glass forming device in the vertical direction. The trough has a depth that decreases between the inlet end and the compression end. The glass forming device further includes a slot that extends along at least a length of the trough in the horizontal direction and extends from the trough to the root of the glass forming device in the vertical direction. Molten glass flows from the trough over the first and second weirs and through the slot.

[0007] In addition, disclosed herein are glass sheets made by the above method as well as electronic devices that include such glass sheets.

[0008] 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.

[0009] 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

[0010] FIG. 1 is a schematic view of an apparatus for producing a glass article including a forming device in accordance with aspects of the disclosure;

[0011] FIG. 2 is a cross-sectional enlarged perspective view of the forming device of FIG. i;

[0012] FIG. 3 is a perspective view of a glass forming device according to embodiments disclosed herein;

[0013] FIG. 4A is an inlet end view of the glass forming device of FIG. 3;

[0014] FIG. 4B is a compression end view of the glass forming device of FIG. 3;

[0015] FIG. 5A is a top view of the glass forming device of FIG. 3;

[0016] FIG. 5B is a bottom view of the glass forming device of FIG. 3; and

[0017] FIG. 6 is an end cutaway view of a glass forming device according to embodiments disclosed herein, wherein heating elements are disposed in proximity to the forming device.

DETAILED DESCRIPTION

[0018] 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.

[0019] As used herein, the term

[0020] FIG. 1 illustrates an exemplary schematic view of a glass forming apparatus 101 for fusion drawing a glass ribbon 103 for subsequent processing into glass sheets. The illustrated glass forming apparatus comprises a fusion draw apparatus, although other fusion forming apparatus may be provided in further examples. The glass forming apparatus 101 can include a melting vessel (or melting furnace) 105 configured to receive batch material 107 from a storage bin 109. The batch material 107 can be introduced by a batch delivery device 111 powered by a motor 113. An optional controller 115 can be configured to activate the motor 113 to introduce a desired amount of batch material 107 into the melting vessel 105, as indicated by arrow 117. A glass level probe 119 can be used to measure a glass melt (or molten glass) 121 level within a standpipe 123 and communicate the measured information to the controller 115 by way of a communication line 125.

[0021] The glass forming apparatus 101 can also include a fining vessel 127, such as a fining tube, located downstream from the melting vessel 105 and fluidly coupled to the melting vessel 105 by way of a first connecting tube 129. A mixing vessel 131, such as a stir chamber, can also be located downstream from the fining vessel 127 and a delivery vessel 133, such as a bowl, may be located downstream from the mixing vessel 131. However, it should be noted that mixing vessel 131 may be positioned upstream from fining vessel 127, and in certain embodiments multiple mixing vessels may be employed, for example a first mixing vessel 131 positioned upstream from fining vessel 127 and a second mixing vessel 131 positioned downstream from fining vessel 127. As shown, a second connecting tube 135 can couple the fining vessel 127 to the mixing vessel 131 and a third connecting tube 137 can couple the mixing vessel 131 to the delivery vessel 133. As further illustrated, a downcomer 139 can be positioned to deliver glass melt 121 from the delivery vessel 133 to an inlet 141 of a forming device 143. As shown, the melting vessel 105, fining vessel 127, mixing vessel 131, delivery vessel 133, and forming device 143 are examples of glass melt stations that may be located in series along the glass forming apparatus 101.

[0022] The melting vessel 105 is typically made from a refractory material, such as refractory (e.g. ceramic) brick. The glass forming apparatus 101 may further include components that are typically made from platinum or platinum-containing metals such as platinum-rhodium, platinum-iridium and combinations thereof, but which may also comprise such refractory metals such as 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 129, the fining vessel 127 (e.g., finer tube), the second connecting tube 135, the standpipe 123, the mixing vessel 131 (e.g., a stir chamber), the third connecting tube 137, the delivery vessel 133 (e.g., a bowl), the downcomer 139 and the inlet 141. The forming device 143 is made from a ceramic material, such as the refractory, and is designed to form the glass ribbon 103.

[0023] FIG. 2 is a cross-sectional perspective view of the glass forming apparatus 101 along line 2-2 of FIG. 1. As shown, the forming device 143 can include a trough 201 at least partially defined by a pair of weirs comprising a first weir 203 and a second weir 205 defining opposite sides of the trough 201. As further shown, the trough may also be at least partially defined by a bottom wall 207. As shown, the inner surfaces of the weirs 203, 205 and the bottom wall 207 define a substantially U shape that may be provided with round corners. In further examples, the U shape may have surfaces substantially 90° relative to one another. In still further examples, the trough may have a bottom surface defined by an intersection of the inner surfaces of the weirs 203, 205. For example, the trough may have a V-shaped profile. Although not shown, the trough can include further configurations in additional examples.

[0024] As shown, the trough 201 can have a depth "D" between a top of the first and/or second weir 203, 205, and bottom wall 207 of the trough 201 that varies along an axis 209 although the depth may be substantially the same along the axis 209. Varying the depth "D" of the trough 201 may facilitate consistency in glass ribbon thickness across the width of the glass ribbon 103. In just one example, as shown in FIG. 2, the depth "Di" near the inlet of the forming device 143 can be greater than the depth "D₂" of the trough 201 at a location downstream from the inlet of the trough 201. As demonstrated by the dashed line 210, the bottom wall 207 may extend at an acute angle relative to the axis 209 to provide a substantially continuous reduction in depth along a length of the forming device 143 from the inlet end to the opposite end.

[0025] The forming device 143 further includes a forming wedge 211 comprising a pair of downwardly inclined forming surface portions 213, 215 extending between opposed ends of the forming wedge 211. The pair of downwardly inclined forming surface portions 213, 215 converge along a downstream direction 217 to form a root 219. A draw plane 221 extends through the root 219 wherein the glass ribbon 103 may be drawn in the downstream direction 217 along the draw plane 221. As shown, the draw plane 221 can bisect the root 219 although the draw plane 221 may extend at other orientations with respect to the root 219.

[0026] The forming device 143 may optionally be provided with one or more edge directors 223 intersecting with at least one of the pair of downwardly inclined forming surface portions 213, 215. In further examples, the one or more edge directors can intersect with both downwardly inclined forming surface portions 213, 215. In further examples, an edge director can be positioned at each of the opposed ends of the forming wedge 211 wherein an edge of the glass ribbon 103 is formed by molten glass flowing off the edge director. For instance, as shown in FIG. 2, the edge director 223 can be positioned at a first opposed end 225 and a second identical edge director (not shown in FIG. 2) can be positioned at a second opposed end (see 227 in FIG. 1). Each edge director 223 can be configured to intersect with both of the downwardly inclined forming surface portions 213, 215. Each edge director 223 can be substantially identical to one another although the edge directors may have different characteristics in further examples. Various forming wedge and edge director configurations may be used in accordance with aspects of the present disclosure. For example, aspects of the present disclosure may be used with forming wedges and edge director configurations disclosed in U.S. Pat. No. 3,451,798, U.S. Patent No.

3,537,834, U.S. Patent No. 7,409,839 and/or U.S. Provisional Pat. Application No.

61/155,669, filed February 26, 2009 that are each herein incorporated by reference in its entirety.

[0027] Embodiments disclosed herein include those in which a slot (not shown in FIG. 2) is present along at least a portion of axis 209. An example of such embodiments is shown in FIGS. 3-6. While certain details of FIG. 2 are not shown in FIGS. 3-6, it is to be understood that such details and related description can be applied to the embodiments shown in FIGS. 3- 6. It should also be understood that the glass forming device shown in FIGS. 3-6 can be used in glass forming apparatus 101.

[0028] FIG. 3 shows a side perspective view of a glass forming device according to embodiments disclosed herein. FIGS. 4A and 4B show, respectively, inlet and compression end views of the embodiment shown in FIG. 3 while FIGS. 5 A and 5B show, respectively, top and bottom views of the embodiment shown in FIG. 3. In the embodiment of FIG. 3-4B, glass forming device 300 includes an inlet end 312, a compression end 314, and a trough 302 extending between the inlet end 312 and the compression end 314. Glass forming device also includes a first side 316 and a second side 318, wherein the first side 316 extends, in the vertical direction, from a first weir 304 on a first side of the trough 302 to a root 330 of the glass forming device. Second side 318 similarly extends, in the vertical direction, from a second weir 306 on a second side of the trough 302 to the root 330 of the glass forming device. As can be seen in FIG. 3, trough 302 has a depth "D" that decreases between inlet end 312 and compression end 314. Accordingly, cross-sectional area of trough 302 (shown, e.g., in FIG. 4A) decreases between inlet end 312 and compression end 314.

[0029] Glass forming device 300 additionally includes a slot 310 that extends along at least a length of trough 302 in the horizontal direction (as shown in e.g., FIGS. 3 and 5A) and extends from the trough 302 to the root 330 of the glass forming device 300 in the vertical direction (as shown, e.g., in FIGS. 3, 4A, and 4B). For example, the slot 310 may extend nearly the entire distance along the trough 302 in the horizontal direction between inlet end 312 and compression end 314 or the slot 310 may extend only a portion of that distance, such as from 10% to 90% of that distance, and further such as from 20% to 80% of that distance.

[0030] As shown in FIGS. 3 and 5B, edge directors 320 and 322 are configured in proximity to root 330 on either end of glass forming device 300.

[0031] In certain exemplary embodiments, such as that shown in FIG. 5A, the slot 310 extending along at least a length of trough 302 in the horizontal direction has a width that increases between the inlet end 312 and the compression end 314. As shown in FIG. 5B, the width "W2" of the slot 310 nearest the compression end 314 is larger than the width "Wl" of the slot 310 nearest the inlet end 312. For example, the width "W2" of the slot 310 nearest the compression end 314 may be at least 10%, such as at least 20%, and further such as at least 50%, and yet further such as at least 100% wider than the width "Wl" of the slot 310 nearest the inlet end 312. For example, the width "Wl" of the slot 310 nearest the inlet end 312 may range from 50% to 90%, such as from 55% to 85%, and further such as from 60% to 80% of the width "W2" of the slot 310 nearest the compression end 314.

[0032] The difference in slot width as a function of distance between the inlet end 312 and compression end 314 can be designed to compensate for the difference in the amount of molten glass (and, hence, pressure of molten glass) in a given cross-sectional area of the trough 302 above the slot 310 when the glass forming device is in full operation, thereby enabling a relatively constant flow of molten glass along the longitudinal length of the slot 310. The relationship between slot width and trough depth will additionally depend on factors such as molten glass viscosity and molten glass density as well as the absolute width of the slot in both the horizontal and vertical directions.

[0033] As shown in FIGS. 3 and 5B, slot 310 extends along a length of the root 330 in the horizontal direction. In certain exemplary embodiments, the slot 310 may extend nearly the entire distance along the root 330 in the horizontal direction or the slot 310 may extend only a portion of that distance, such as from 5% to 95% of that distance, and further such as from 10% to 90% of that distance.

[0034] In certain exemplary embodiments, such as that shown in FIG. 3, the horizontal length "L2" of the slot 310 extending along a length of the root 330 is longer than the horizontal length "LI" of the slot 310 extending along a length of the trough 302. In other embodiments (not shown), the horizontal length of the slot along the root may be

approximately equal to or shorter than the horizontal length of the slot along the trough. When the horizontal length of the slot 310 along a length of the root 330 is longer than the horizontal length of the slot 310 along a length of the trough 302, the length "L2" may be at least 5%, such as at least 10%, and further such as at least 15% longer than the length "LI", such as from 5% to 30% longer, including from 10% to 25% longer, and further including from 15% to 20% longer.

[0035] A slot with a relatively long horizontal length along the length of the root can at least partially compensate for attenuation (i.e., shortening of the width) of the molten glass ribbon that flows over the weirs and down the first and second sides of the glass forming device by diverting the flow of molten glass through the slot toward the outermost edges of the molten glass ribbon. This can potentially increase the quality area of the molten glass ribbon, that is, the area of the glass ribbon that comprises a substantially uniform thickness, and can allow for greater control of bead formation of the outermost edges of the ribbon.

[0036] In the embodiment shown in FIG. 5B, slot 310 extending along a length of root 330 has a width that is approximately constant along most of its length and is tapered at its ends (near edge directors 320 and 322). For example, slot 310 extending along a length of root 330 may have a width that is approximately constant along at least a majority of its length, such as at least 75% of its length, and further such as at least 85% of its length, and yet further such as at least 95% of its length, and even yet further such as substantially all of its length (such that the ends of slot 310 extending along a length of root 330 are not tapered). A slot 310 extending along a length of root 330 having a width that is approximately constant along at least a majority of its length can further enable a molten glass ribbon with approximately constant width.

[0037] Accordingly, the embodiment shown in FIGS. 5A and 5B show a slot 310

extending along at least a length of trough 302 in the horizontal direction that has a width that increases between the inlet end 312 and the compression end 314 (wherein "W2" > "Wl"), wherein the slot 310 extends with an approximately constant width along at least a majority of the length of root 330. This embodiment (as shown in FIG. 3) also shows the slot 310 having a horizontal length "L2" extending along a length of the root 330 that is longer than the horizontal length "LI" of the slot 310 extending along a length of the trough 302.

[0038] FIG. 6 shows an end cutaway view of a glass forming device according to embodiments disclosed herein wherein a glass ribbon 103 is formed below root 330 of glass forming device 300. As shown in FIG. 6, molten glass flows from the trough 302, over the first weir 304, and down the first side 316 toward the root 330. Molten glass also flows from the trough 302, over the second weir 306, and down the second side 318 toward the root 330. In addition, molten glass flows from the trough 302 and down through the slot 310 toward the root 330. Molten glass ribbon 103 is formed as molten glass flowing over the first and second weirs 304, 306, joins molten glass flowing through the slot 310 at the root 330.

[0039] In the embodiment shown in FIG. 6, heating elements 350A-D are disposed in proximity to the forming device (while FIG. 6 shows four heating elements, it is to be understood that embodiments herein include those comprising greater or fewer numbers of heating elements). Heating elements 350A-D may, for example, comprise electrically resistive heating elements, such as those disclosed in U.S. published patent application number 2008/0282736, the entire disclosure of which is incorporated herein by reference. In that regard, while heating elements 350A-D are shown schematically in FIG. 6 as having rectangular or parallelogram cross-sections, it is to be understood that heating elements may have any geometrical configuration or cross- section, including circular and elliptical cross- sections.

[0040] Heating elements 350A-D can be configured so as to provide additional control over the temperature of molten glass flowing over the first and second weirs, 304, 306. For example, heating elements 350A-D may be configured and operated to enable the

temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, to be within a predetermined temperature range relative to the temperature of molten glass arriving at the root 330 from the slot 310. For example, heating elements 350A-D may be configured and operated such that the temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, is within 20°C, such as within 10°C, and further such as within 5°C of the temperature of molten glass arriving at the root 330 from the slot 310. Heating elements 350A-D may be configured and operated such that the

temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, is approximately equal to the temperature of molten glass arriving at the root 330 from the slot 310. Maintaining the temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, within a predetermined range relative to the temperature of molten glass arriving at the root 330 from the slot 310 can, for example, enable improved glass ribbon flow and glass sheet properties.

[0041] While embodiments disclosed herein include those in which molten glass is fed to the glass forming device 300 via a single inlet (such as inlet 141 shown in FIG. 1), embodiments disclosed herein also include those comprising a first molten glass feed to the glass forming device 300 and a second molten glass feed to the glass forming device 300, wherein the first molten glass feed is configured to primarily direct molten glass flow over the first and second weirs 304, 306, and the second molten glass feed is configured to primarily direct molten glass flow into the slot 310. Accordingly, embodiments disclosed herein include introducing a first molten glass feed to the glass forming device and a second molten glass feed to the glass forming device 300, wherein a majority of molten glass from the first molten glass feed flows over the first and second weirs 304, 306, and a majority of molten glass from the second molten glass feed flows into the slot 310. Preferably, the first molten glass feed will be vertically higher than the second molten glass feed.

[0042] In certain exemplary embodiments, at least 60%, such as at least 70%, and further such as at least 80%, and yet further such as at least 90% of the first molten glass feed, including from 60% to 99% and further including from 70% to 95% of the first molten glass feed flows over the first and second weirs 304, 306. Such embodiments may include those in which, at least 60%, such as at least 70%, and further such as at least 80%, and yet further such as at least 90% of the second molten glass feed, including from 60% to 99% and further including from 70% to 95% of the second molten glass feed flows into the slot 310.

[0043] When first and second molten glass feeds are used, the composition of the first and second molten glass feeds may be the same or different. The temperature of the first and second molten glass feeds may also be the same or different. For example, in some embodiments, the temperature of the first molten glass feed may be at least somewhat higher than the temperature of the second molten glass feed, such as at least 5°C higher, and further such as at least 10° higher, including from 5°C to 100°C higher, such as from 10°C to 50°C higher.

[0044] Maintaining the first molten glass feed at a higher temperature than the second molten glass feed may, depending on glass composition, flow transport characteristics, and other conditions, enable more of the first molten glass feed to flow over the first and second weirs 304, 306, as a result of lower relative density at higher temperature and, hence, increased buoyancy within trough 302. Maintaining the first molten glass feed at a higher temperature than the second molten glass feed may also further enable the temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, to be within a predetermined temperature range relative to the temperature of molten glass arriving at the root 330 from the slot 310 without the necessity of heating elements, such as heating elements 350A-D. For example, maintaining the first molten glass feed at a predetermined higher temperature than the second molten glass feed may enable the temperature of molten glass arriving at the root 330 from over the first and second weirs, 304, 306, to be approximately equal to the temperature of molten glass arriving at the root 330 from the slot 310 without the necessity of heating elements, such as heating elements 350A-D.

[0045] The percentage of total flow density of molten glass introduced to the glass forming device 300 (via one or more molten glass feeds) that flows into the slot 310 (as opposed to over the weirs, 304, 306), while not limited, can range from, for example, 5% to 95%, such as from 10%) to 90%, and further such as from 20% to 80%>, and yet further such as from 30%> to 70%), and still yet further such as from 40% to 60%>. In certain embodiments, at least 50%, such as at least 60%, and further such as at least 70% of the total flow density of molten glass introduced to the glass forming device 300 flows into the slot 310.

[0046] The area of the slot 310 extending along a length of the trough 302, relative to the total area of the bottom of the trough 302, while not limited, can range from, for example, 5% to 50%), such as from 10% to 40%, and further such as from 15% to 30%, and yet further such as from 20% to 25% of the total area of the bottom of the trough 302.

[0047] The glass forming device 300, while not limited to any particular material, may, in certain exemplary embodiments, comprise a refractory material that has minimal reactivity to the molten glass formed using the device. Exemplary materials for the glass forming device include, but are not limited to an isopressed zircon-based ceramic material, such as those disclosed in US patent application publication numbers 2004/0055338 and 2005/0130830, the entire disclosures of which are incorporated herein by reference. Exemplary materials for the glass forming device may also include an isopressed xenotime-based or xenotime-stabilized zircon-based ceramic material, such as those disclosed in US patent application publication number 2009/0131241, the entire disclosure of which is incorporated herein by reference.

[0048] Glass forming devices comprising slot 310 can be made by one of any variety of methods. For example, glass forming devices according to embodiments disclosed herein may be made by bonding two substantially mirror image halves of the glass forming device together, wherein the region comprising the slot 310 is formed, routed, or cut out of each half. Methods for bonding components of glass forming devices are disclosed, for example, in U.S. patent no. 7,988,804, the entire disclosure of which is incorporated herein by reference. Methods for cutting or removing material from glass forming devices are disclosed, for example, in U.S. patent publication no. 2014/0318523, the entire disclosure of which is incorporated herein by reference. [0049] Embodiments disclosed herein can enable the production of glass articles, such as glass sheets, while providing at least one advantage over previously known methods, such as advantages discussed elsewhere herein. Moreover, embodiments disclosed herein can enable the production of glass articles, such as glass sheets, wherein the weight of the glass forming device 300 is significantly reduced for a given molten glass flow density relative to the weight of previously known glass forming devices. For example, for a given molten glass flow density, the weight of the glass forming device 300, may be at least 10% less, such as at least 20%) less, and further such as at least 30%> less, and yet further such as at least 40% less, including from 10%> less to 50% less than previously known glass forming devices.

Embodiments, disclosed herein can also enable the production of glass articles, such as glass sheets, wherein the temperature of the glass forming device 300 is lower for a given molten glass flow density relative to the weight of previously known glass forming devices. For example, for a given molten glass flow density, the temperature of the glass forming device 300, may be at least 20°C, such as at least 50°C, and further such as at least 100°C lower, such as from 20°C to 200°C lower than previously known glass forming devices. Lowering the weight and/or temperature of the glass forming device for a given molten glass flow rate can mitigate a number of potential disadvantages, such as a glass forming device that is subject to increased deformation over time and/or increased erosion or chemical attack of the glass forming device. Alternatively stated, embodiments herein can enable the production of glass articles, such as glass sheets, wherein the molten glass flow density is higher while minimizing at least one of the disadvantages discussed herein.

[0050] Glass articles, including glass sheets, made by methods disclosed herein can be used in a variety of applications, including flat glass panels and screens incorporated into electronic devices, such as LCD televisions and handheld electronic devices. In such glass sheets, the middle portion of the glass sheet in a thickness direction will be provided from glass flowed through slot 310 whereas first and second surface areas of the glass sheets will be provided from glass flowed over weirs 304, 306. For example, in certain embodiments at least 20%), such as at least 30%>, and further such as at least 40%, and yet further such as at least 50%), and still yet further such as at least 60%>, including from 20% to 80%, and further including from 30% to 70% of the total thickness of the glass sheet may be provided from glass flowed through the slot 310. [0051] In such manner, production of relatively thin, flat glass sheets with high surface quality can be achieved at potentially lower production costs relative to previously known production methods.

[0052] While specific embodiments disclosed herein have been described with respect to an overflow downdraw process, it is to be understood that the principle of operation of such embodiments may also be applied to other glass forming processes such as flow processes and slot draw processes.

[0053] 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 producing a glass article comprising:

a glass forming device comprising:

an inlet end and a compression end and a trough extending between the inlet end and the compression end;

a first side and a second side that each extend from the inlet end to the compression end in a horizontal direction, wherein the first side extends from a first weir on a first side of the trough to a root of the glass forming device in a vertical direction and the second side extends from a second weir on a second side of the trough to the root of the glass forming device in the vertical direction;

wherein the trough has a depth that decreases between the inlet end and the compression end; and

wherein the glass forming device further comprises a slot that extends along at least a length of the trough in the horizontal direction and extends from the trough to the root of the glass forming device in the vertical direction.

2. The apparatus of claim 1, wherein the slot that extends along at least a length of the trough has a width that increases between the inlet end and the compression end.

3. The apparatus of claim 2, wherein the width of the slot nearest the compression end is at least twice the width of the slot nearest the inlet end.

4. The apparatus of claim 1, wherein the slot extends along a length of the root in the horizontal direction, wherein the horizontal length of the slot extending along the length of the root is longer than the horizontal length of the slot extending along a length of the trough.

5. The apparatus of claim 4, wherein each end of the slot extending along the length of the root is tapered.

6. The apparatus of claim 1, wherein the apparatus further comprises a first molten glass feed to the glass forming device and a second molten glass feed to the glass forming device, wherein the first molten glass feed is configured to direct molten glass flow over the first and second weirs and the second molten glass feed is configured to direct molten glass flow into the slot.

7. The apparatus of claim 1, wherein the apparatus further comprises at least one heating element disposed in proximity to the glass forming device.

8. A method of producing a glass article, the method comprising introducing molten glass to a glass forming device, the glass forming device comprising:

wherein the trough has a depth that decreases between the inlet end and the compression end;

wherein the glass forming device further comprises a slot that extends along at least a length of the trough in the horizontal direction and extends from the trough to the root of the glass forming device in the vertical direction; and

wherein molten glass flows from the trough over the first and second weirs and through the slot.

9. The method of claim 8, wherein the slot that extends along at least a length of the trough has a width that increases between the inlet end and the compression end.

10. The method of claim 9, wherein the width of the slot nearest the compression end is at least twice the width of the slot nearest the inlet end.

11. The method of claim 8, wherein the slot extends along a length of the root in the horizontal direction, wherein the horizontal length of the slot extending along a length of the root is longer than the horizontal length of the slot extending along a length of the trough.

12. The apparatus of claim 11, wherein each end of the slot extending along the length of the root is tapered.

13. The method of claim 8, wherein the method further comprises introducing a first molten glass feed to the glass forming device and a second molten glass feed to the glass forming device, wherein a majority of molten glass from the first molten glass feed flows over the first and second weirs and a majority of molten glass from the second molten glass feed flows into the slot.

14. The method of claim 13, wherein the composition of the first and second molten glass feeds is the same.

15. The method of claim 13, wherein the composition of the first and second molten glass feeds is different.

16. The method of claim 13, wherein a temperature of the first and second molten glass feeds is different.

17. The method of claim 8, wherein at least 50% of a total flow density of molten glass introduced to the glass forming device flows into the slot.

18. The method of claim 8, wherein molten glass flowing over the first and second weirs joins molten glass flowing through the slot at the root, wherein a temperature of molten glass arriving at the root from over the first and second weirs is within 20°C of a temperature of molten glass arriving at the root from the slot.

19. A glass sheet made by the method of claim 8.

20. An electronic device comprising the glass sheet of claim 19.