Apparatus and method for modifying flow of molten glass

Abstract

A method of modifying a flow of molten glass, the method comprising: flowing the molten glass from a forming body into a molten glass ribbon; and intersecting the molten glass ribbon with a flow control member spaced from a bottom edge of the molded body and extending a predetermined distance in the molten glass ribbon from an edge of the molten glass ribbon, the flow control member is configured such that the molten glass flows through opposing first and second major surfaces of the flow control member.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 646228, filed May 13, 2024, pursuant to 35 USC § 119, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure generally relates to an apparatus for forming glass strips by a pull-down method, and more specifically, to controlling a flow of molten glass drawn from a molded body. Background Technology

[0004] In a method for manufacturing thin, high-quality glass for purposes such as display devices, a molten precursor material (hereinafter referred to as molten glass) flows from a forming body to form a molten glass ribbon, which cools into a solid glass ribbon in an elastic state as the ribbon descends from the bottom edge of the forming body. The ribbon can then be cut into separate glass sheets for further processing and subsequently transported to an equipment manufacturer.

[0005] As the molten glass ribbon descends from the molded body, its width decreases, and its lateral edges thicken. These thickened edge portions are commonly referred to as beads. Both of these effects reduce the total usable area of ​​the glass ribbon and result in manufacturing losses. Therefore, manufacturing yield can be improved by increasing the ribbon width and / or reducing the size of the unusable edge portions.

[0006] In other cases, such as for ultrathin glass, the size of the lateral edge itself (rather than the width of the strip) may be the primary concern. Summary of the Invention

[0007] A ribbon of molten glass from a molded body (e.g., from a fusion-draw or slot-draw process) can undergo lateral attenuation, where the lateral edges of the ribbon are drawn inwards. On the other hand, this reduction in lateral extension results in an increase in the thickness of the edge portions of the glass ribbon. This can render those thickened edge portions (spherical edges) commercially unavailable. According to embodiments disclosed herein, a flow control device is disclosed that can produce thinner spherical edges, increasing the usable glass, thereby improving manufacturing efficiency and reducing the amount of precious metals (e.g., platinum) used in the manufacturing process.

[0008] Flow control components not attached to the formed body have limited practicality unless heated, and it has been proven difficult to heat devices embedded in free-flowing glass. For current ribbon forming processes, flow control components positioned below the bottom edge of the formed body should be less than approximately 5 mm thick, allowing glass to flow over both sides of the flow control component. The flow control component also needs a surface temperature above the glass liquidus temperature (typically above 1000°C). On the other hand, at temperatures above 1000°C, oxidation of the heating element becomes a problem, limiting the lifespan of the heating unit. Conflicting with the thinness requirement, the flow control component must also exhibit sufficient strength to resist the tensile forces of the ribbon. Another requirement for the heating unit used in removable flow control components is that the heating unit must be durable enough to be inserted into the cavity of the flow control component. This is not insignificant, as the gap between the cavity and the heating unit should be kept small to allow for good thermal coupling between the heating unit and the surface of the flow control component.

[0009] Therefore, in a first aspect, an apparatus for drawing molten glass ribbons is disclosed, the apparatus comprising: a forming body configured to form a molten glass stream into a molten glass ribbon; and a flow control device. The flow control device includes a support arm and a flow control member coupled to the support arm. The flow control member includes a first main surface and a second main surface opposite to the first main surface; and a heating unit disposed in a cavity between the first and second main surfaces of the flow control member, the heating unit including a resistance heating element having a rectangular cross-section and disposed between a first ceramic plate and a second ceramic plate bonded using a ceramic adhesive.

[0010] The resistance heating element may include a rectangular cross-section.

[0011] The maximum thickness of the resistance heating element can be less than or equal to about 2.2 mm, for example, in the range of about 0.5 mm to about 2.2 mm.

[0012] The maximum width of the resistance heating element can be less than or equal to about 2.2 mm.

[0013] In an embodiment, the thickness of at least one of the first ceramic plate or the second ceramic plate may be equal to or less than about 0.2 mm.

[0014] In an embodiment, the first and second main surfaces may comprise platinum, such as a platinum alloy, for example, a platinum-rhodium alloy. The platinum alloy may comprise aluminum.

[0015] In this embodiment, the resistance heating element comprises platinum, such as a platinum alloy, or a platinum-rhodium alloy. The platinum alloy may contain aluminum.

[0016] The flow control device can be configured to move the flow control component in the horizontal direction, move the flow control component in the vertical direction, and / or rotate the flow control component.

[0017] In an embodiment, the flow control device may include a linear actuator configured to change the position of a flow control member, and may include a plurality of linear actuators configured to move the flow control member in a plurality of mutually orthogonal directions.

[0018] The flow control device may include a mounting plate, wherein a support arm is removably engaged in an opening slot in the mounting plate.

[0019] In an embodiment, the flow control component includes a first surface half and a second surface half. The first surface half includes a first recess on the surface of the first surface half, and the second surface half includes a second recess on the surface of the second surface half. The first surface half is welded to the second surface half with the first recess facing the second recess, and the facing recess forms a cavity.

[0020] Flowing molten glass from a molded body may include flowing molten glass from the bottom edge of the molded body, where the converging molding surface of the molded body converges at the bottom edge.

[0021] The flow control component may have a plate-like structure, and the first main surface and the second main surface may be parallel to each other.

[0022] In some embodiments, the flow control member may have a plate-like structure, wherein the flow control member may include a first main surface and a second main surface through which the molten glass ribbon flows, and the first main surface and the second main surface of the flow control member are parallel to a vertical plane passing through the bottom edge of the molded body.

[0023] In some embodiments, the flow control member includes a first main surface and a second main surface through which the molten glass ribbon flows, and the molten glass ribbon flows over the entire surface area of ​​the first main surface and the second main surface.

[0024] The flow control component can be positioned between the uppermost edge roller and the bottom edge of the molded body.

[0025] In some embodiments, the surface area of ​​the flow control member wetted by molten glass can be varied.

[0026] In some embodiments, the distance between the uppermost edge of the flow control member wetted by the molten glass ribbon and the bottom edge of the molded body can be varied.

[0027] The apparatus may further include a plurality of flow control elements, each of which extends a predetermined distance from the edge of the molten glass ribbon in the molten glass ribbon such that at least a portion of the total surface area of ​​the flow control elements is wetted by the molten glass.

[0028] In another aspect, an apparatus for drawing molten glass ribbons is described, comprising: a forming body from which molten glass ribbons are drawn; and a flow control device including a flow control member vertically positioned below and spaced apart from the forming body, the flow control member including opposing flat surfaces, the flow control member being spaced apart from and positioned at a predetermined distance from a vertical plane extending through the bottom edge of the forming body and perpendicular to the longitudinal axis of the forming body, such that molten glass ribbons from the forming body can flow over the main surface of the flow control member.

[0029] The flow control device may further include a positioning device configured to change a predetermined distance. The flow control device may be configured to move the flow control member in a vertical direction, in a horizontal direction, or in both vertical and horizontal directions.

[0030] The apparatus for drawing molten glass ribbons may further include a plurality of flow control devices, each of which includes a flow control component.

[0031] In another aspect, a method for modifying the flow of molten glass is disclosed, comprising: causing molten glass to flow from a molded body into a molten glass ribbon; and causing the molten glass ribbon below the molded body to intersect with a flow control member, the flow control member being spaced apart from the molded body and extending a predetermined distance in the edge portion of the molten glass ribbon, such that at least a portion of the flow control member is wetted by the molten glass ribbon, the flow control member including a flat first main surface and a flat second main surface opposite to the flat first main surface.

[0032] The method may further include: heating the flow control component using a heating unit disposed within a cavity of the flow control component, the heating unit comprising a resistance heating element disposed between a pair of ceramic plates having an individual thickness equal to or less than about 0.2 mm and bonded together with refractory cement, the heating unit heating to a temperature equal to or greater than about 1000°C. The thickness of the resistance heating element may be equal to or less than about 2.2 mm, and the width of the resistance heating element may be equal to or less than about 2.2 mm.

[0033] In one embodiment, the resistance heating element may include a serpentine pattern. The resistance heating element may also include a rectangular cross-sectional shape orthogonal to the longitudinal axis of the resistance heating element.

[0034] In some embodiments, the flow control member may be movable in the vertical direction and / or vertically. In some embodiments, the flow control member may be rotatable.

[0035] In one embodiment, the flow control component can be removed from the molten glass ribbon as it flows from the molded body.

[0036] Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description below, and some features and advantages will be readily apparent to those skilled in the art from the description, or will be recognized by practice of the embodiments described herein, including the detailed description below, the claims, and the drawings.

[0037] It should be understood that both the foregoing general description and the following detailed description present embodiments of this disclosure and are intended to provide an overview or framework for understanding those embodiments. The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and form a part of this specification. The drawings illustrate various embodiments of this disclosure and, together with the description, serve to explain the principles and operation of the embodiments. Attached Figure Description

[0038] Figure 1 A front view of an example glass-making apparatus according to an embodiment of this disclosure;

[0039] Figure 2 This is a stylized cross-sectional view of a glass ribbon formed by a pull-down process, showing the spherical edge (edge ​​portion) and mass region of the ribbon;

[0040] Figure 3 for Figure 1 A cross-sectional view of the molded body;

[0041] Figure 4 A close-up view of the placement of an example flow control component positioned above the edge rollers and below the bottom edge of the molded body;

[0042] Figure 5 A side view of an example flow control device according to an embodiment of this disclosure;

[0043] Figure 6 for Figure 5 Another side view of an example flow control device;

[0044] Figure 7 A side view of a mounting plate configured to couple flow control equipment to a glass forming apparatus;

[0045] Figure 8 for Figure 6 A longitudinal cross-sectional view of the flow control device, showing the electrically insulating tube housed therein;

[0046] Figure 9 A side view of a portion of an example flow control component, including a heating unit contained therein;

[0047] Figure 10 for Figure 9 A top view of an example flow control component;

[0048] Figure 11 A cross-sectional side view of an example heating unit according to an embodiment of this disclosure;

[0049] Figure 12 This is a side view of an example heating unit, where the ceramic plate has been removed and the resistance heating element is shown.

[0050] Figure 13 A top view of another example flow control device according to an embodiment of this disclosure;

[0051] Figure 14 for Figure 13 A cross-sectional view of the covering component of the flow control device;

[0052] Figure 15 for Figure 14 A side view of the flow control device;

[0053] Figure 16 A perspective view of another example flow control component;

[0054] Figure 17 Here is a cross-sectional view of an example spherical edge defect;

[0055] Figure 18 Here is a cross-sectional view of another example of a spherical edge defect;

[0056] Figure 19 A perspective view of another example of a molten glass molded body; and

[0057] Figure 20 To show from Figure 19 The diagram shows the thickness distribution of a glass strip drawn from the molded body when no flow control member is positioned in the molten glass strip drawn from the molded body, and the thickness distribution of a glass strip drawn from the same molded body when a flow control member is positioned in the molten glass strip drawn from the molded body. Detailed Implementation

[0058] Reference will now be made in detail to various embodiments of this disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. While embodiments of the flow control device described herein can be used in various pull-down glass manufacturing processes, including but not limited to slot drawing and fusion processes, the following embodiments are described in the case of fusion processes.

[0059] Figure 1 An exemplary glass manufacturing apparatus 10 is shown. The glass manufacturing apparatus 10 may include a glass melting furnace 12 comprising a melting vessel 14. In addition to the melting vessel 14, the glass melting furnace 12 may optionally include one or more additional components, such as heating elements (e.g., burners and / or electrodes) configured to heat the raw material and convert it into a molten material (hereinafter referred to as molten glass). For example, the melting vessel 14 may be an electrically assisted melting vessel, wherein energy is added to the raw material via two burners and by direct heating, wherein an electric current passes through the raw material, thereby adding energy to the raw material via Joule heating.

[0060] In other embodiments, the glass melting furnace 12 may include other thermal management devices (e.g., insulation components) to reduce heat loss from the melting vessel. The glass melting furnace 12 may further include electronic and / or electromechanical devices that facilitate melting the raw materials into molten glass. The glass melting furnace 12 may include support structures (e.g., support chassis, support members, etc.) or other components.

[0061] The melting container 14 may be formed of a refractory material, such as a refractory ceramic material, for example, a refractory ceramic material comprising alumina or zirconium oxide, but the refractory ceramic material may include other refractory materials used alternatively or in any combination, such as yttrium (e.g., yttrium oxide, yttrium oxide-stabilized zirconium oxide, yttrium phosphate), zircon (ZrSiO4), or alumina-zirconia-silica, or even chromium oxide. In some examples, the melting container 14 may be constructed of refractory ceramic bricks.

[0062] In embodiments, the glass melting furnace 12 may be incorporated as a component of a glass manufacturing apparatus configured to manufacture glass articles, such as glass ribbons, but may also be configured to form other glass articles, such as, but not limited to, glass rods, glass tubes, glass claddings (e.g., glass claddings for lighting devices, such as light bulbs), and glass lenses. Many other glass articles are contemplated. In some examples, the melting furnace may be included in a glass manufacturing apparatus that includes a float bath, a down-drawing apparatus (e.g., a fusion down-drawing apparatus or a groove drawing apparatus), an up-drawing apparatus, a pressing apparatus, a rolling apparatus, a tube drawing apparatus, or any other glass manufacturing apparatus that would benefit from this disclosure. By way of example, Figure 1A glass melting furnace 12, which is a component of a fusion-draw glass manufacturing apparatus 10, is schematically shown. It is used to fuse drawn glass strips for subsequent processing into individual glass sheets or to roll the glass strips into spools.

[0063] Glass manufacturing apparatus 10 may optionally include upstream glass manufacturing apparatus 16 located upstream of melting vessel 14. In some examples, a portion or all of upstream glass manufacturing apparatus 16 may be incorporated as part of glass melting furnace 12.

[0064] like Figure 1 As shown in the embodiments illustrated, the upstream glass manufacturing equipment 16 may include a raw material storage bin 18, a raw material delivery device 20, and an electric motor 22 connected to the raw material delivery device 20. The raw material storage bin 18 may be configured to store a quantity of raw material 24, which may be fed into a melting vessel 14 through one or more inlets, as indicated by arrow 26. The raw material 24 typically comprises one or more glass-forming metal oxides and one or more modifiers. In some examples, the raw material delivery device 20 may be powered by the electric motor 22 to deliver a predetermined quantity of raw material 24 from the raw material storage bin 18 to the melting vessel 14. In other examples, the electric motor 22 may power the raw material delivery device 20 to introduce the raw material 24 at a controlled rate based on a molten glass level sensed downstream of the melting vessel 14 relative to the flow direction of the molten glass. The raw material 24 within the melting vessel 14 may then be heated to form molten glass 28.

[0065] The glass manufacturing apparatus 10 may also include a downstream glass manufacturing apparatus 30 positioned downstream of the glass melting furnace 12 relative to the flow direction of the molten glass 28. In some examples, a portion of the downstream glass manufacturing apparatus 30 may be incorporated as part of the glass melting furnace 12. For example, in some cases, the first connecting conduit 32 discussed below or other portions of the downstream glass manufacturing apparatus 30 may be incorporated as part of the glass melting furnace 12.

[0066] Downstream glass manufacturing equipment 30 may include a first conditioning (i.e., processing) chamber, such as a refining vessel 34, located downstream of the molten vessel 14 and coupled to the molten vessel 14 via the aforementioned first connecting conduit 32. Molten glass 28 may be gravity-fed from the molten vessel 14 to the refining vessel 34 via an internal passage of the first connecting conduit 32. Thus, the first connecting conduit 32 provides a flow path for the molten glass 28 from the molten vessel 14 to the refining vessel 34. However, other conditioning chambers may be located downstream of the molten vessel 14, for example, between the molten vessel 14 and the refining vessel 34. In some embodiments, a conditioning chamber may be employed between the molten vessel and the refining vessel. For example, although not shown, the molten glass from the primary molten vessel may be further heated in a secondary molten (conditioning) vessel located between the molten vessel 14 and the refining vessel 34, or the molten glass may be cooled in the secondary molten vessel to a temperature lower than that of the molten glass in the primary molten vessel before entering the refining vessel.

[0067] Bubbles can be removed from the molten glass 28 using various techniques. For example, the raw material 24 may include a multivalent compound (i.e., a clarifying agent) that undergoes a chemical reduction reaction upon heating and releases oxygen, such as tin oxide. Other suitable clarifying agents may include, but are not limited to, arsenic, antimony, iron, cerium, and various sulfates, but arsenic and antimony may not be usable for environmental reasons in some applications. The clarifying container 34 may be heated, for example, to a temperature greater than that of the molten container, thereby further heating the clarifying agent. Oxygen generated by the temperature-induced chemical reduction of one or more clarifying agents included in the molten glass via further heating diffuses into the bubbles generated during the melting process. The enlarged bubbles with increased buoyancy can then rise to the free surface of the molten glass within the clarifying container and subsequently exit from the clarifying container.

[0068] The downstream glass manufacturing apparatus 30 may further include another conditioning vessel, such as a mixing device 36, or a stirring vessel, for mixing the molten glass flowing downstream of the clarifying vessel 34. The mixing device 36 can be used to provide a homogeneous molten glass composition, thereby reducing chemical or thermal inhomogeneities that may otherwise exist within the molten glass leaving the clarifying chamber. As shown, the clarifying vessel 34 may be coupled to the mixing device 36 by means of a second connecting conduit 38. In some embodiments, the molten glass 28 may be gravity-fed from the clarifying vessel 34 to the mixing device 36 by means of an internal passageway in the second connecting conduit 38. The molten glass in the mixing device 36 may include a free surface and a free volume extending between the free surface and the top of the mixing device. As used herein, the free volume is a gaseous volume, typically containing no liquid material. Similarly, a free surface refers to the surface of the molten glass within a vessel or conduit and represents the interface between a liquid (e.g., the molten glass) and a gaseous atmosphere above the molten glass. While the mixing device 36 is shown downstream of the clarifying vessel 34 relative to the flow direction of the molten glass, in other embodiments, the mixing device 36 may be positioned upstream of the clarifying vessel 34. In some embodiments, the downstream glass manufacturing apparatus 30 may include multiple mixing devices, such as a mixing device upstream of the clarifying vessel 34 and a mixing device downstream of the clarifying vessel 34. These mixing devices may have the same design or may have different designs from each other. For example, one or more of the vessel and / or conduit may include static mixing blades positioned therein to facilitate mixing and subsequent homogenization of the molten material.

[0069] The downstream glass manufacturing apparatus 30 may further include another regulating chamber, such as a delivery container 40 located downstream of the mixing apparatus 36. The delivery container 40 may regulate the feeding of molten glass 28 to the downstream forming apparatus. For example, the delivery container 40 may act as a reservoir and / or flow controller to regulate the coherent flow of the molten glass 28 and provide the coherent flow to the formed body 42 via an outlet conduit 44. In some embodiments, the molten glass within the delivery container 40 may include a free surface from which a free volume extends upward to the top of the delivery container. As shown, the mixing apparatus 36 may be coupled to the delivery container 40 via a third connecting conduit 46. In some examples, the molten glass 28 may be gravity-fed from the mixing apparatus 36 to the delivery container 40 via an internal passageway of the third connecting conduit 46.

[0070] The downstream glass manufacturing equipment 30 may further include a forming device 48, which includes the aforementioned forming body 42 and an inlet conduit 50. An outlet conduit 44 may be positioned to deliver molten glass 28 from the delivery container 40 to the inlet conduit 50 of the forming device 48.

[0071] Components of the downstream glass manufacturing apparatus 30, including any one or more of connecting conduits 32, 38, 46, a clarifying vessel 34, a mixing device 36, a delivery vessel 40, an outlet conduit 44, or an inlet conduit 50, may be formed of precious metals. Suitable precious metals include platinum group metals or alloys thereof selected from the group consisting of platinum, iridium, rhodium, osmium, ruthenium, and palladium. For example, downstream components of the glass manufacturing apparatus may be formed of a platinum-rhodium alloy comprising about 70% to about 90% by weight of platinum and about 10% to about 30% by weight of rhodium. In some embodiments, these components may be formed of more than about 90% by weight of platinum, such as more than 92% by weight, more than 94% by weight, more than 96% by weight, more than 98% by weight, and even up to 100% by weight of platinum. However, other suitable metals for forming downstream components of the glass manufacturing apparatus may include molybdenum, rhenium, tantalum, titanium, tungsten, and alloys thereof.

[0072] The forming body 42 in the fusion-draw glass manufacturing apparatus may include a groove 52 positioned in the upper surface of the forming body and a converging forming surface 54 (only one surface is shown) that converges along the bottom edge (root) 56 of the forming body in the drawing direction. Molten glass delivered to the groove 52 of the forming body via a delivery container 40, an outlet conduit 44, and an inlet conduit 50 overflows the wall of the groove 52 and descends along the converging forming surface 54 as a separate stream of molten glass. The separate stream of molten glass converges along the root 56 and below the root to produce a single strip 58 of molten glass, which is drawn from the root 56 along the drawing plane 60 in the drawing direction 60 by applying downward tension to the glass strip (e.g., by gravity and / or traction roller assembly 62) to control the size of the glass strip as the molten glass cools and its viscosity increases. Thus, the glass strip 58 undergoes a viscoelastic transition to an elastic state and acquires the mechanical properties that produce stable dimensional characteristics of the glass strip 58. The glass strip 58 includes a first outer edge 64a and a second outer edge 64b opposite to the first outer edge 64a, the first and second outer edges extending longitudinally along the glass strip 58 (see also...). Figures 2 to 3The glass strip 58 may further include a first thickened edge portion 66a and a second thickened edge portion 66b (hereinafter referred to as the first spherical edge 66a and the second spherical edge 66b, respectively), and spherical edges 66a, 66b extending inwardly from the respective first outer edge 64a and the second outer edge 64b. The glass strip 58 includes a width defined between the first outer edge 64a and the second outer edge 64b. The first spherical edge 66a and the second spherical edge 66b may include a thickness greater than the thickness of the glass strip along its longitudinal centerline. The glass strip extending between the first spherical edge 66a and the second spherical edge 66b may be referred to as the “quality” region 68 of the glass strip. The quality region 68 exhibits a substantially uniform thickness and a pristine or substantially pristine surface, and is the most commercially valuable portion of the strip, as spherical edges are typically removed and discarded or used as glass shavings. In some embodiments, the glass strip 58 can be separated into individual glass sheets 70 by a glass separation device 72, but in other embodiments, the glass strip 58 can be wound onto a spool and stored for further processing.

[0073] Each traction roller assembly 62 includes a pair of traction rollers arranged along the edge of the glass strip. Typically, the traction roller pairs are positioned in opposite relationships. There may be at least one pair of traction roller assemblies, with one or more traction roller assemblies positioned along opposite edges of the glass strip, such that the traction rollers are configured with four traction rollers per group, and a pair of traction rollers positioned equidistant from the root 56 along each edge of the glass strip. However, more than one group of traction rollers may be used, wherein the groups of traction rollers are sequentially positioned in the drawing direction 60, such that a second group of traction rollers can be positioned below the first group of traction rollers relative to the drawing direction. In an embodiment, a set of edge roller assemblies 74 may be disposed between the root 56 and the uppermost traction roller.

[0074] As the molten glass ribbon 58 descends, surface tension, gravity, and tension cause the ribbon width to decrease (attenuation), while the molten glass ribbon remains at a formable viscosity. This attenuation causes the edge portions 66a, 66b of the molten glass ribbon to increase in thickness relative to the center region of the ribbon. These thickened edge portions may be referred to as spherical edges. Unlike the traction roller assembly 62, the edge roller assembly 74 is configured to contact the edge of the glass ribbon at the spherical edge as the molten glass flows from the bottom edge of the formed body, while the glass ribbon flows from the root 56 and the edge portions are rapidly cooled, thereby increasing the viscosity of the edge portions and aiding in maintaining the width of the glass ribbon. The edge roller assembly 74 can be actively cooled. For example, in one embodiment, individual edge rollers may include cooling channels in fluid communication with a coolant source, wherein the coolant flow in the edge roller cools the edge roller and thereby cools the edge portions of the glass ribbon.

[0075] The mass region of the glass strip positioned between the spheres has a generally uniform thickness. Typically, after the strip has reached its final thickness, the thickness of the mass region is equal to or less than about 2 mm, for example, equal to or less than about 1 mm, or equal to or less than about 0.7 mm. In some embodiments, after the strip has reached its final thickness, the thickness of the mass region ranges from about 0.1 mm to about 0.7 mm. In yet other embodiments, the final thickness of the mass region may range from about 0.01 mm to about 0.1 mm. As described, edge portions 66a, 66b represent deviations from the desired strip thickness. Furthermore, for ultra-thin glass strips, such as those where the thickness of the mass region is about 0.1 mm or less, the thickened edge portions can be an obstacle to rolling the glass strip into a roll shape (e.g., rolling it on a receiving reel during a winding process). Therefore, the thickened edge portions can be removed. In some processes, the thickened edge portions can be removed from individual glass sheets cut from the glass strip. In other processes, the thickened edge portions can be removed directly from the strip during the drawing process. In either case, the commercially usable width of the glass strip 58 is reduced, at least because the total width of the molten glass strip decreases and the thickened edge portions 66a, 66b of the molten glass strip become thicker than the mass region and must eventually be removed.

[0076] Return to Figure 1 The process outlines how molten glass ribbons are drawn from the bottom edge 56 of the forming body 42 by the influence of gravity and, for example, by the opposing rotating roller pairs of the traction roller assembly 62, which are positioned such that the opposing rollers of each pair grip the thickened edge portions 66a, 66b and apply a downward pulling force to the molten glass ribbon 58. Other rollers in the edge roller assembly are the uppermost rollers in contact with the glass ribbon and are configured to cool the edge portions 66a, 66b of the glass ribbon 58 and help maintain the width of the glass ribbon after the molten glass leaves the bottom edge of the forming body. Similar to the traction roller assembly, the edge rollers of the edge roller assembly are arranged in the opposite relationship when engaging the edge portions of the glass ribbon. The spherical edges 66a, 66b are undesirable because they represent a localized increase in the thickness of the glass ribbon and must be removed before selling the glass sheets cut from the ribbon. Thus, the spherical edges 66a, 66b represent a waste of manufacturing process and an unwanted cost.

[0077] Therefore, an apparatus is described that can produce a strip width increase more efficiently than the achievable width, even as the glass strip is drawn from the exposed bottom edge of the formed body, while producing a smaller thickened edge portion than with conventional edge guides. Furthermore, the apparatus can be applied to other pull-down type glass strip forming processes and is not dependent on the structure of the forming equipment.

[0078] Figures 3 to 12An example flow control device 100 is shown, configured to control the width of a glass strip 58 as it is drawn from a forming body 42. The flow control device 100 includes a flow control member 102 positioned below and spaced apart from, but close to, the bottom edge 56 of the forming body 42. Multiple flow control devices 100 may be positioned along one or both edges of the glass strip. Figure 4 As shown, the uppermost edge 104 of each flow control member 102 may be positioned, for example, at a distance D of at least 1 cm below the bottom edge 56 of the forming body 42, for example, within a range of about 1 cm to about 5 cm. Therefore, the flow control member 102 is positioned between the edge roller assembly 74 and the bottom edge 56, but does not contact the forming body 42. The lack of contact between the flow control member 102 and the forming body 42 allows for the replacement of the flow control member 102 during operation of the glass manufacturing equipment (e.g., while the molten glass is still flowing). According to an embodiment of the invention, the flow control member 102 may be configured with a first main surface and a second main surface, namely, a first main surface 106 and a second main surface 108 (see...). Figure 6 The first main surface 106 and the second main surface 108 may be, for example, planar and parallel, such that the flow control member 102 has a plate-like configuration. Furthermore, the first main surface 106 and the second main surface 108 may be parallel to a vertical plane 76 passing through the bottom edge 56 (see...). Figure 3 ,in Figure 3 (A cross-sectional view of the molded body 42, edge roller assembly 74, and traction roller assembly 62 as seen from the end of the molded body.) Figure 4 As best shown, the flow control member 102 may have a generally rectangular shape. However, the flow control member 102 may include one or more curved edges. Additionally, the main surfaces 106, 108 need not be planar or parallel. For example, the main surfaces 106, 108 may be curved or include curved portions.

[0079] The flow control member 102 is arranged to intersect the free flow of glass from the bottom edge 56 of the forming body 42 before the molten glass reaches the edge roller assembly 74, such that the edge portions (spherical edges) 66a, 66b of the molten glass ribbon 58 flow over and around at least a portion of the flow control member. That is, the flow control member 102 not only contacts the glass flow but also extends a predetermined distance in the flow of the molten glass ribbon 58, such that the molten glass flows over and wets at least a portion of the two main surfaces 106, 108 of the flow control member 102. The molten glass flow may not necessarily cover the entire main surface of the flow control member. Therefore, a portion of the main surface of the flow control member may remain unwetted by the molten glass.

[0080] For example, depicting the side view and top view of the flow control device 100 respectively. Figures 5 to 6As shown, the flow control member 102 may be coupled to the support arm 110. The support arm 110 may include a support tube 112 including a support tube flange 114. A support shaft 116 is slidably and / or rotatably engaged with the support tube 112. That is, the support tube 112 includes a passage through which the support shaft 116 extends, and the longitudinal position of the support shaft 116 within the passage can be changed by longitudinally sliding the support shaft 116 within the support tube 112. A bracket 118 may be attached to a first end 120 of the support shaft 116, and the flow control member 102 may be attached to the support shaft 116 via the bracket 118 (e.g., by suitable fasteners (e.g., screws or bolts)). A second end 122 of the support shaft 116 extends from the support tube 112 opposite to the first end 120. That is, the first end 120 of the support shaft 116 extends from the first end 124 of the support tube 112, and the second end 122 of the support shaft 116 extends from the second end (e.g., the support tube flange 114) of the support tube 112. The support shaft 116 may include a mark 126 arranged to facilitate repeated positioning of the support shaft 116 within the support tube 112, thereby controlling the placement of the flow control member 102 relative to the molten glass flow from the molding body 42. However, other forms of position determination known in the art can be used to determine the longitudinal position of the support shaft 116, such as digital readout devices. For example, the longitudinal position of the support shaft 116 can be determined by the distance (e.g., a predetermined distance) of the flow control member 102 from a vertical plane passing through the center of the molding body 42 and orthogonal to the vertical plane 76.

[0081] The flow control device 100 may further include a mounting plate 128 and a support shaft collar 130. For example... Figure 7 As shown, mounting plate 128 includes a slot 132 sized to receive support tube 112, wherein support tube flange 114 can be removably mounted to mounting plate 128 using suitable fasteners (e.g., screws or bolts). Thus, support tube 112 can be positioned in slot 132 and secured to mounting plate 128 via support tube flange 114. If replacement or repair of any component of flow control member 102 or support arm 110 is required, support arm 110 can be disengaged from mounting plate 128 by loosening the fasteners securing support tube flange 114 (e.g., support arm 110) to mounting plate 128 and sliding the support arm from slot 132. Mounting plate 128 may additionally include mounting slot 134 configured to secure mounting plate 128 to a portion of molding equipment 48 using suitable fasteners (e.g., bolts), wherein mounting slot 134 may be elongated, thereby allowing vertical adjustment of mounting plate position before tightening fasteners. Mounting plate 128 may include, for example, markings 136 near mounting slot 132 to facilitate vertical positioning of the mounting plate.

[0082] Now refer to the description of the support arm 110 in the longitudinal cross-section. Figure 8 The support shaft 116 may be a hollow shaft, further comprising a porous electrically insulating tube 138 extending along the length of the support shaft through a passage. That is, the electrically insulating tube 138 may include, for example, two or more holes extending along the length of the electrically insulating tube, wherein electrical leads (e.g., wires) may extend through separate holes in electrical contact tabs for connection to a heating unit (described below) within the flow control member 102. For example, typically two electrical leads are used, one through a first hole 140a of the electrically insulating tube 138, and a second through a second hole 140b of the electrically insulating tube 138. The electrically insulating tube 138 may be a ceramic tube, such as a ceramic tube comprising alumina, but other high-temperature electrically insulating materials may be used, such as other high-temperature low-conductivity refractory materials (e.g., zirconium oxide).

[0083] The position of the flow control member 102 relative to the molten glass flow (e.g., glass ribbon 58) can be obtained by sliding the support shaft 116 within the support tube 112. For example, the support shaft collar 142 may include a passage through which the support shaft 116 extends when the support shaft collar 142 is placed on the support shaft. Methods for securing the support shaft collar 142 to the support shaft 116 can be provided. For example, the support shaft collar 142 may be an open collar comprising a first half and a second half, wherein the first and second halves of the support shaft collar 142 may be placed around the support shaft 116 and secured to the support shaft by means of fasteners extending through a passage (bolt hole) in the first half of the support shaft collar 142 and engaging the second half of the support shaft collar 142, for example, by means of mating threads. More simply, during assembly, the inner diameter of the support shaft collar passage is smaller than the outer diameter of the support shaft 116, and the support shaft collar 142 is secured to the support shaft 116 when the first and second halves of the support shaft collar 142 are bolted together and tightened. The maximum lateral dimension (e.g., width, diameter) of the support shaft collar 142 is greater than the inner diameter of the support tube passage, thereby preventing the support shaft 116 from being inserted into the support tube 112 through the support shaft collar 142 (i.e., when the support shaft collar is adjacent to the support tube (e.g., the support tube flange)). Other methods of securing the support shaft collar 142 include slit support shaft collars. Slit support shaft collars comprise a single slit extending through the thickness of the support shaft collar 142. Bolts arranged with bolt holes on opposite sides of the slit can then be used to pull the two ends defining the slit together, thereby tightening the support shaft collar 142 onto the support shaft 116. In yet another method, the inner diameter of the support shaft passage may be slightly larger than the outer diameter of the support shaft 116, and the support shaft collar 142 includes a flat-head screw with a threaded passage screwable into the support shaft collar, the threaded passage extending orthogonally to the passage through which the support shaft extends. Tightening the flat-head screw engages with the support shaft 116, thereby securing the support shaft collar 142 to the support shaft 116.

[0084] See also Figure 9 and 10The diagram shows a side view and a top side view of an example flow control member 102, which includes a blade portion 144 and one or more tab portions 146 extending therefrom. For example, the tab portions 146 may be arranged orthogonally to the blade portion 144. The blade portion 144 may include a pair of covering members, such as a first covering member 144a and a second covering member 144b, which are welded together along the interface between the covering members. However, the blade and tab portions may be formed from a single strip of material and folded to create the flow control member 102. The tab portions 146 may include apertures 148 that facilitate securing the flow control member 102 to a bracket 118 using suitable fasteners, such as screws or bolts. In an embodiment, the tab portions 146 may be formed by bending portions of the covering portions 144a, 144b to an appropriate angle to mount the flow control member 102 to the bracket 118.

[0085] In embodiments, for example, the flow control member 102 of the covering member may include a material compatible with the molten glass. Compatibility means that the material comprising the flow control member 102 is not readily dissolved in or detached from the molten glass, and is capable of prolonged exposure to the high temperatures of the molten glass without significant material degradation or shape deformation. The molten glass to which the flow control member 102 is exposed may be, for example, at a temperature equal to or greater than about 700°C, equal to or greater than 800°C, or even equal to or greater than 900°C, for example, in the temperature range of about 700°C to about 1200°C. As described, each flow control member 102 may comprise platinum or a platinum alloy, such as a platinum-rhodium alloy or a platinum-iridium alloy. Alternative materials may include ZrSiO4 or Haynes® alloys. Compatible materials may also include materials that dissolve over time, but the dissolved material becomes a harmless part of the overall molten glass composition and does not materially affect the performance of the resulting glass article. In some embodiments, the flow control member 102 may comprise a suitable silicate or non-silicate glass, or a suitable ceramic material. Therefore, the material including the flow control member 102 can be determined based on the temperature of the material (e.g., molten glass) exposed to the flow control member.

[0086] The flow control component 102 may further include a heating unit 150 disposed inside the impeller portion 144. For example, in the embodiment and in Figure 10As shown, the flow control member 102 includes an internal cavity 152 sized to accommodate the heating unit 150. For example, one or both covering portions 144a, 144b may include recesses such that when the covering portions are joined, the internal cavity 152 is formed. The heating unit 150 can be used to locally control the temperature of the flow control member 102, and thus control the viscosity of the molten glass flowing through the flow control member 102. For example, in the case of drawing glass at temperatures below the liquidus temperature of the glass, continuous or intermittent heating of the flow control member 102 can be used to prevent devitrification of the glass. In fact, the use of the flow control member according to the embodiments described herein can be used to intentionally draw glass ribbons at temperatures below the liquidus temperature of the glass. Alternatively, in the case where devitrification accumulates at the flow control member, the devitrification can be removed by heating.

[0087] Instead, refer to the cross-sectional view depicting the edge of the heating unit 150. Figure 11 The heating unit 150 includes a resistance heating element 154 sandwiched between a thin ceramic plate 156 and an electrical connection lead 158 (e.g., a connecting tab) attached to the end of a heating element. The connection lead 158 can be used to electrically connect the heating element 154 to a power source. The ceramic plate 156 may be formed, for example, from a ceramic strip and cut from the ceramic strip, for example, by laser, electrical discharge machining (EDM), or other suitable methods. In embodiments, the resistance heating element may be deposited (e.g., printed) and cured or sintered in liquid or slurry form. An adhesive 160 (e.g., a ceramic adhesive) may be used to hold the heating element 154 and the ceramic plate 156 together. For example, a suitable ceramic adhesive is Ceramabond™ 503 (manufactured by Aremco Products, Valley Cottage, NY).

[0088] In an embodiment, the thickness T1 of the individual ceramic plate 156 may be equal to or less than about 2.0 mm, for example, in the range of about 0.07 mm to about 0.2 mm, in the range of about 0.07 mm to about 0.15 mm, in the range of about 0.07 mm to about 0.13 mm, in the range of about 0.07 mm to about 0.12 mm, in the range of about 0.07 mm to about 0.11 mm, in the range of about 0.07 mm to about 0.10 mm, in the range of about 0.07 mm to about 0.09 mm, in the range of about 0.7 mm to about 0.08 mm, including all ranges and subranges therein.

[0089] The thickness T2 of the heating element 154 may be in the range of about 0.5 to about 2.2 mm, for example in the range of about 0.6 mm to about 1.0 mm, in the range of about 0.7 mm to about 1.0 mm, in the range of about 0.8 mm to about 1.0 mm, in the range of about 0.9 mm to about 1.0 mm, in the range of about 0.9 mm to about 0.5 mm, in the range of about 0.8 mm to about 0.5 mm, in the range of about 0.7 mm to about 0.5 mm, or in the range of about 0.6 mm to about 0.5 mm, including all ranges and subranges therein.

[0090] In an embodiment, when assembled with ceramic plate 156, heating element 154 and adhesive 160, the total thickness T3 of heating unit 150 can be in the range of about 0.75 mm to about 2.5 mm. Figure 12 This is a top view of the heating unit 150, with the ceramic plate 156 removed to reveal the interior of the heating unit and the heating elements therein. The width W of the heating element 154 may range from about 0.5 to about 1 mm, and the spacing S between adjacent portions of the heating element may range from about 0.5 mm to about 1 mm. The heating element 154 can be machined by CNC milling a pure platinum strip followed by EDM wire cutting to remove the heating element from the strip. Other suitable materials for the heating element 154 may include platinum alloys, such as platinum-rhodium alloys, for example, platinum-rhodium alloys comprising platinum in the range of about 70 wt% to about 100 wt% and rhodium in the range of about 0 wt% to about 30 wt%. In some embodiments, the heating element may comprise a platinum-aluminum alloy, such as a platinum-aluminum alloy comprising aluminum in the range of about 5 wt% to about 10 wt%. Other suitable materials may include molybdenum disilicide or iron-chromium-aluminum (FeCrAl) alloys, such as Kanthal®. The heating element 154 can be formed in a serpentine shape to maximize the surface area of ​​the flow control member, thereby avoiding unheated cold spots on the flow control member caused by square corners of the impeller portion that the heating element cannot reach. These cold spots can serve as nucleation sites for forming deglassing glass. Additionally, sharp bends in the heating element (e.g., square corners) can adversely affect heating. Although not shown, adhesive 160 can fill the gaps between the legs of the heating element, thereby helping to maintain the shape of the heating element. To ensure good thermal coupling between the heating element 154 and the covering portions 144a and 144b, the heating element can be rectangular (e.g., square) in cross-section, as using a circular heating element would hinder such thermal coupling.

[0091] The modeling has shown that, more generally, changing the surface area of ​​the flow control member wetted by the molten glass alters the velocity of the molten glass flowing through the main surface of the flow control member. As the velocity of the molten glass flowing through the surface of the flow control member decreases, the attenuation also decreases.

[0092] See Figure 13 The image shows a top view of another example flow control device 200, which includes a support arm 202 comprising a bracket 204. A flow control member 206 may be coupled to the bracket portion 204 via suitable fasteners (e.g., bolts or screws). The support arm 202 may be coupled to one or more linear stages configured to move the support arm 202 along one or more mutually orthogonal axes, thereby moving the flow control member 206. For example, as... Figure 13 As shown, the support arm 202 can be coupled to three linear stages configured to move the support arm 202 along three mutually orthogonal axes. For example, the first linear stage (actuator) 208 can be configured to move the support arm 202 along an X-axis orthogonal to the drawing direction 60. The second linear stage 210 can be configured to move the support arm 202 along a Y-axis orthogonal to both the X-axis and the drawing direction 60. The third linear stage 212 can be configured to move the support arm 202 along a Z-axis parallel to the drawing direction 60 and orthogonal to both the Y-axis and the X-axis (where the Z-axis is orthogonal to the plane of the drawing). Cover member 214 (see...) Figure 14 The cover member 214 may be fixed above the flow control member 206, for example, to protect the flow control member from molten glass that may adhere to it, making it more difficult to remove the flow control member 206 from the support 204. The cover member 214 may include an opening 216 sized to receive a fastener 218 that secures the cover member 214 to the flow control member 206 and / or the support 204.

[0093] from Figures 15-16Ideally, the flow control member 206 includes: a blade portion 220 configured to be at least partially inserted into the molten glass flow; and a tab portion 222 extending from the blade portion 220, for example parallel to it, and configured to secure the tab portion 222 and, consequently, the blade portion 220 to the bracket 204, and further to the support arm 202. In an embodiment, the tab portion 222 may be an extension of at least a portion of the blade portion 220. For example, the flow control member may include a first covering portion 224a and a second covering portion 224b, wherein the tab portion 222 is a portion of the second covering portion 224b extending beyond the first covering portion 224a. That is, the second covering portion 224b may be longer than the first covering portion 224a. In an embodiment, the tab portion 222 may include one or more orifices 226 through which the tab portion can be attached to the bracket 204, for example, by suitable fasteners, such as screws or bolts. The tab portion 222 may include an opening 228 for receiving and covering the mounting fastener 218. Like the flow control member 102, the flow control member 206 may include an internal cavity sized to receive the heating unit 150. Once assembled, the first and second covering portions of the flow control member 206 can be welded together, thereby enclosing the heating unit 184 within the cavity.

[0094] In addition to reducing the size of the thickened edge portion and reducing attenuation (lateral shrinkage), the use of the flow control member 102 or flow control member 206 according to embodiments of the present disclosure can also help enhance the bonding of separate glass flows. Figure 17 Examples of thickened edge portions 66a, 66b are shown, wherein a flow of molten glass from the molded body (a flow from a converging molding surface of the molded body 42) has not yet fully combined with the opposing flow of molten glass, thereby forming a notch or pit 300 in the edge portions 66a, 66b. In some cases, in Figure 18 As shown, such indentations can create air lines 302. These edge anomalies, and especially air lines, can disrupt the cutting process, for example, by causing the cut line to deviate from its intended path when cutting different glass sheets from the glass strip. Alternatively, such edge anomalies can generate stresses in the edges of the strip that adversely affect the shape of the central portion (mass region) of the strip or the glass sheets cut from it. In yet another case, the presence of air lines can lead to uncontrolled cracking of the strip. Modeling has shown that embodiments of the flow control components described herein can be used to reduce the formation of these pits and / or air lines.

[0095] The heating unit described herein can be formed by placing a first ceramic plate in a slot in an assembly fixture. Ceramic adhesive is then spread across the surface of the ceramic plate while the plate remains in the fixture. A resistance heating element, shaped appropriately for the ceramic plate, is then centered on the surface of the ceramic plate, ensuring that the ceramic adhesive covers the interface between the surface and the resistance heating element. The resistance heating element leads are then clamped, and additional ceramic adhesive is spread onto the resistance heating element, with a slightly excessive amount of adhesive applied.

[0096] The second ceramic plate is then placed over the resistance heating element, and the interlayer is gently squeezed to remove air pockets and excess ceramic adhesive. A cover plate can then be placed over the interlayer and clamped in place to secure the heating unit components, allowing the ceramic adhesive to harden (partially cure) but not harden.

[0097] The partially cured heating unit can be removed from the clamp, along with any excess ceramic adhesive, such as that at the edges of the heating unit. The partially cured heating unit can then be returned to the clamp, re-clamped, and processed according to the required curing of the ceramic adhesive to complete the curing process. For example, the heating unit can be placed in a boiler to complete the curing process.

[0098] While many of the discussions set forth in this disclosure relate to a molded body including grooves, the flow control devices described herein, such as flow control devices 100 and 200, are applicable to other pull-down glass forming processes. For example, Figure 19 An alternating molded body 400 is shown, comprising a tube 402 (e.g., a cylindrical tube) including a slot 404 disposed at the top (apex) of the tube. The molded body is shown in cross-section, depicting only half of the molded body. Molten glass is delivered from a delivery container 406 to the tube 402 via a connecting conduit 408, the molten glass then flows upward and exits the slot 404, and then flows downward above a converging molded surface 410 that converges along the bottom edge 412. The molten glass exits the bottom edge 412 as a molten glass ribbon. Barriers 414 are disposed at both ends of the tube (only one is shown) to prevent the molten glass flow from passing through the ends of the molded body. Flow control devices are positioned below the bottom edge 412.

[0099] Figure 20A graph illustrating the variation of strip width as a function of position between a molding apparatus 400 including a molded body 400 without flow control devices 100 or 200 (i.e., flow control members inserted into the glass flow beneath the molded body) and the same molding apparatus with flow control devices 100 or 200, where the zero position indicates the center of the molded body. The data show that operation without the flow control devices disclosed herein results in thick edges and a U-shaped thickness distribution (curve 416), which limits the usable strip width. Consistent with modeling results, when using the flow control devices disclosed herein, the glass strip is wider and exhibits a substantially flat thickness distribution (curve 418).

[0100] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of this disclosure without departing from the spirit and scope thereof. Therefore, it is intended that this disclosure cover such modifications and variations, provided that such modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. An apparatus for drawing molten glass ribbons, the apparatus comprising: A molded body configured to form a molten glass stream into a molten glass ribbon; Flow control device, the flow control device comprising: Support arm; A flow control component coupled to the support arm, the flow control component including a first main surface and a second main surface opposite to the first main surface, and arranged such that the molten glass ribbon contacts and flows through the first main surface and the second main surface; and A heating unit is disposed in a cavity between the first main surface and the second main surface of the flow control member, the heating unit comprising a resistance heating element bonded by a ceramic adhesive between the first ceramic plate and the second ceramic plate.

2. The device according to claim 1, wherein the resistance heating element comprises a rectangular cross-section.

3. The device according to claim 2, wherein the maximum thickness of the resistance heating element is less than or equal to about 2.2 mm.

4. The device according to claim 3, wherein the maximum thickness is in the range of about 0.5 mm to about 2.2 mm.

5. The device according to claim 2, wherein the maximum width of the resistance heating element is less than or equal to about 2.2 mm.

6. The device according to claim 1, wherein the thickness of at least one of the first ceramic plate or the second ceramic plate is equal to or less than about 0.2 mm.

7. The device of claim 1, wherein the first main surface and the second main surface comprise platinum.

8. The device of claim 1, wherein the resistance heating element comprises platinum.

9. The device of claim 8, wherein the resistance heating element comprises aluminum.

10. The apparatus of claim 1, wherein the flow control device is configured to move the flow control member in a horizontal direction.

11. The apparatus of claim 1, wherein the flow control device is configured to move the flow control member in a vertical direction.

12. The device of claim 1, wherein the flow control device includes a linear actuator configured to change the position of the flow control member.

13. The device of claim 11, wherein the flow control device comprises a plurality of mutually orthogonal linear actuators.

14. The device of claim 1, wherein the flow control device includes a mounting plate, and the support arm is removably engaged in an opening slot in the mounting plate.

15. The device of claim 1, wherein the flow control member comprises a first surface half and a second surface half, the first surface half including a first recess on a surface of the first surface half, the second surface half including a second recess on a surface of the second surface half, and the first surface half being welded to the second surface half such that the first recess faces the second recess, the facing recess forming the cavity.

16. A method for modifying a molten glass flow, the method comprising: This causes the molten glass to flow from the molded body into a ribbon-like molten glass structure. The molten glass ribbon below the molded body intersects with the flow control member, the flow control member being spaced apart from the molded body and extending a predetermined distance in the edge portion of the molten glass ribbon, such that at least a portion of the flow control member is wetted by the molten glass ribbon, the flow control member including a flat first main surface and a flat second main surface opposite to the flat first main surface; as well as The flow control component is heated using a heating unit disposed within a cavity of the flow control component. The heating unit includes a resistance heating element disposed between a pair of ceramic plates having an individual thickness equal to or less than about 0.2 mm and bonded together with refractory cement. The heating unit heats the component to a temperature equal to or greater than about 1000°C. The thickness of the resistance heating element is equal to or less than about 2.2 mm, and the width of the resistance heating element is equal to or less than about 2.2 mm.

17. The method of claim 16, wherein the resistance heating element comprises a serpentine pattern.

18. The method of claim 16, wherein the resistance heating element comprises a rectangular cross-sectional shape.

19. The method of claim 16, the method further comprising moving the flow control member in a vertical direction.

20. The method of claim 16, the method further comprising moving the flow control member in a horizontal direction.

21. The method of claim 16, further comprising replacing the flow control member while the molten glass ribbon flows from the molded body.

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