Patent Application
20240391813
The present disclosure relates to apparatus for forming molten glass, and more particularly to conduits for conveying the molten glass wherein the conduits include reinforcing members to prevent collapse of the conduit.
Manufacturing apparatus for forming molten glass typically include conduits configured to convey the molten glass from one station of the apparatus to another station. For example, a conduit can extend between a melting vessel and a downstream component such as a stirring vessel. Because of the high temperature and corrosive nature of molten glass, many components of the manufacturing apparatus are formed from temperature and corrosion resistant metals, often selected from the platinum groups metals. These components are often thin-walled owing to the expense of these metals. For certain glasses, processing temperatures can be near the melting temperature of the metal. Because the metal may be very thin, the component structures may therefore lack significant strength and be prone to collapse over time.
In a first aspect, a glass forming apparatus is disclosed, comprising: a conduit comprising a metal conduit wall defining an interior passage of the conduit, the conduit configured to carry a flow of molten glass through the interior passage; and at least one reinforcing member extending around at least a portion of an external periphery of the conduit and attached to the metal conduit wall, the at least one reinforcing member positioned between and spaced apart from a pair of adjacent electrical flanges.
In a second aspect, the at least one reinforcing member of the first aspect may extend across at least an upper portion of the metal conduit wall.
In a third aspect, the at least one reinforcing member of the first aspect or the second aspect may extend circumferentially around the conduit.
In a fourth aspect, the at least one reinforcing member of any of the first through the third aspects may comprise a plurality of reinforcing members.
In a fifth aspect, the at least one reinforcing member of any of the first through the fourth aspects may comprise a hollow interior.
In a sixth aspect, the at least one reinforcing member of any of the first through the fifth aspects may comprise a pressure equalization orifice providing fluid communication between the hollow interior and an atmosphere external to the reinforcing member hollow interior.
In a seventh aspect, the metal conduit wall of any of the first through the sixth aspects, may comprise platinum.
In an eighth aspect, the at least one reinforcing member according to any of the first through the seventh aspect may comprise platinum.
In a ninth aspect, the glass forming apparatus according to any of the first to the eighth aspect may be a fining vessel.
In a tenth aspect, the at least one reinforcing member of any of the first to the ninth aspect may be attached to the conduit by plates.
In an eleventh aspect, the at least one reinforcing member of the tenth aspect may be spaced apart from the conduit by a gap.
In a twelfth aspect, a cross-sectional shape of the at least one reinforcing member of any of the first aspect through the eleventh aspect may be rectangular or circular.
In a thirteenth aspect, a glass forming apparatus is described, comprising: a fining vessel comprising a metal wall defining an interior passage of the fining vessel, the fining vessel configured to carry a flow of molten glass through the interior passage; and at least one reinforcing member extending around at least a portion of an external periphery of the fining vessel and attached to the metal wall, the at least one reinforcing member positioned between and spaced apart from a pair of adjacent electrical flanges.
In a fourteenth aspect, the at least one reinforcing member of the thirteenth aspect may extend circumferentially around the fining vessel.
In a fifteenth aspect, the metal wall of the fourteenth aspect or the fifteenth aspect may comprise platinum.
In a sixteenth aspect, the at least one reinforcing member of any of the thirteenth to the fifteenth aspect may comprise platinum.
In a seventeenth aspect, the at least one reinforcing member of any of the thirteenth aspect to the sixteenth aspect may comprise a hollow interior.
Both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description explain the principles and operations thereof.
Reference will now be made in detail 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. However, this disclosure can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value to the other particular value. Similarly, when values are expressed as approximations by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
Directional terms as used herein—for example, up, down, right, left, front, back, top, bottom—are made only with reference to the figures as drawn and are not intended to imply absolute orientation.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components: plain meaning derived from grammatical organization or punctuation, and: the number or type of embodiments described in the specification.
As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.
The word “exemplary,” “example,” or various forms thereof are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” or as an “example” should not be construed as preferred or advantageous over other aspects or designs. Furthermore, examples are provided solely for purposes of clarity and understanding and are not meant to limit or restrict the disclosed subject matter or relevant portions of this disclosure in any manner. It can be appreciated that a myriad of additional or alternate examples of varying scope could have been presented but have been omitted for purposes of brevity.
As used herein, the terms “comprising” and “including,” and variations thereof, shall be construed as synonymous and open-ended, unless otherwise indicated. A list of elements following the transitional phrases comprising or including is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present.
The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.
As used herein, the term conduit refers generally to a structure defining a hollow interior configured to convey molten glass therethrough. Conduits may be configured for conveyance purposes or structured to perform additional functions. For example, structures configured for removing gases from molten glass, although referred to as fining vessels herein, nevertheless belong generically to the family of conduits.
Shown in
Glass melting furnace 12 may include other thermal management devices (e.g., thermal insulation components) that reduce heat loss from the melting vessel. Glass melting furnace 12 can include electronic and/or electromechanical devices that facilitate melting of the raw material into a glass melt. Glass melting furnace 12 can include support structures (e.g., support chassis, support member, etc.) or other components.
Melting vessel 14 may be formed from a refractory material, for example a refractory ceramic material comprising alumina or zirconia, although the refractory ceramic material can comprise other refractory materials, such as yttrium (e.g., yttria, yttria-stabilized zirconia, yttrium phosphate), zircon (ZrSiO4) or alumina-zirconia-silica or even chrome oxide, used either alternatively or in any combination. In some examples, melting vessel 14 may be constructed from refractory ceramic bricks.
Glass melting furnace 12 may be incorporated as a component of a glass manufacturing apparatus configured to fabricate a glass article, for example a glass ribbon, although the glass manufacturing apparatus can be configured to form other glass articles without limitation, such as glass rods, glass tubes, glass envelopes (for example, glass envelopes for lighting devices, e.g., light bulbs) and glass lenses. In some examples, melting furnace 12 may be included in a glass manufacturing apparatus comprising a slot draw apparatus, a float bath apparatus, a down-draw apparatus (e.g., a fusion down draw apparatus), an up-draw apparatus, a pressing apparatus, a rolling apparatus, a tube drawing apparatus or any other glass manufacturing apparatus that would benefit from the present disclosure. By way of example,
Glass manufacturing apparatus 10 may optionally include an upstream glass manufacturing apparatus 16 positioned upstream of melting vessel 14. In some examples, a portion of, or the entire upstream glass manufacturing apparatus 16, can be incorporated as part of the glass melting furnace 12.
As shown in
Glass manufacturing apparatus 10 may also include a downstream glass manufacturing apparatus 30 positioned downstream of glass melting furnace 12 relative to a flow direction of molten glass 28. In some examples, a portion of downstream glass manufacturing apparatus 30 may be incorporated as part of glass melting furnace 12. For example, first connecting conduit 32 discussed below, or other portions of the downstream glass manufacturing apparatus 30, can be incorporated as part of the glass melting furnace 12.
Downstream glass manufacturing apparatus 30 can include a first conditioning chamber, such as fining vessel 34, located downstream from melting vessel 14 and coupled to melting vessel 14 by way of the above-referenced first connecting conduit 32. In some examples, molten glass 28 may be gravity fed from melting vessel 14 to fining vessel 34 by way of an interior pathway of first connecting conduit 32. Accordingly, first connecting conduit 32 provides a flow path for molten glass 28 from melting vessel 14 to fining vessel 34. However, other conditioning chambers may be positioned downstream of melting vessel 14, for example between melting vessel 14 and fining vessel 34. In some embodiments, a conditioning chamber may be employed between the melting vessel and the fining chamber. For example, molten glass from a primary melting vessel can be further heated in a secondary melting (conditioning) vessel or cooled in the secondary melting vessel to a temperature lower than the temperature of the molten glass in the primary melting vessel before entering the fining chamber.
Bubbles may be removed from molten glass 28 by various techniques. For example, raw material 24 may include multivalent compounds (i.e., fining agents) such as tin oxide that, when heated, undergo a chemical reduction reaction and release oxygen. Other suitable fining agents can include without limitation arsenic, antimony, iron, and/or cerium, although the use of arsenic and antimony, owing to their toxicity, may be discouraged for environmental reasons in some applications. Fining vessel 34 is heated, for example to a temperature greater than the melting vessel interior temperature, thereby heating the fining agent. Oxygen produced by the temperature-induced chemical reduction of one or more fining agents included in the molten glass can diffuse into gas bubbles produced during the melting process. The enlarged gas bubbles with increased buoyancy then rise to a free surface of the molten glass within the fining vessel and can thereafter be vented from the fining vessel, for example through a vent tube in fluid communication with the atmosphere above the free surface.
Downstream glass manufacturing apparatus 30 may further include another conditioning chamber, such as mixing apparatus 36, for example a stirring vessel, for mixing the molten glass that flows downstream from fining vessel 34. Mixing apparatus 36 may be used to provide a homogenous glass melt composition, thereby reducing chemical and/or thermal inhomogeneities that may otherwise exist within the molten glass exiting the fining vessel. As shown, fining vessel 34 may be coupled to mixing apparatus 36 by way of a second connecting conduit 38. Accordingly, molten glass 28 can be gravity fed from the fining vessel 34 to mixing apparatus 36 through an interior pathway of second connecting conduit 38. For instance, gravity may drive molten glass 28 from fining vessel 34 to mixing apparatus 36. Typically, the molten glass within mixing apparatus 36 includes a free surface, with a free (e.g., gaseous) volume extending between the free surface and a top of the mixing apparatus. While mixing apparatus 36 is shown downstream of fining vessel 34 relative to a flow direction of molten glass 28, mixing apparatus 36 may be positioned upstream from fining vessel 34 in other embodiments. In some embodiments, downstream glass manufacturing apparatus 30 may include multiple mixing apparatus, for example a mixing apparatus upstream from fining vessel 34 and a mixing apparatus downstream from fining vessel 34. When used, multiple mixing apparatus may be of the same design, or they may be of a different design from one another. One or more of the vessels and/or conduits may include static mixing vanes positioned therein to promote mixing and subsequent homogenization of the molten material.
Downstream glass manufacturing apparatus 30 may further include another conditioning chamber such as delivery vessel 40 located downstream from mixing apparatus 36. Delivery vessel 40 can act as an accumulator and/or flow controller to adjust and/or provide a consistent flow of molten glass 28 to forming body 42 by way of exit conduit 44. The molten glass within delivery vessel 40 can, in some embodiments, include a free surface, wherein a free volume extends upward from the free surface to a top of the delivery vessel. As shown, mixing apparatus 36 can be coupled to delivery vessel 40 by way of third connecting conduit 46. In some examples, molten glass 28 can be gravity fed from mixing apparatus 36 to delivery vessel 40 through an interior pathway of third connecting conduit 46.
Downstream glass manufacturing apparatus 30 may further include forming apparatus 48 comprising the above-referenced forming body 42, including inlet conduit 50. Exit conduit 44 can be positioned to deliver molten glass 28 from delivery vessel 40 to inlet conduit 50 of forming apparatus 48. Forming body 42 in a fusion down-draw glass making apparatus can comprise a trough 52 positioned in an upper surface of the forming body, and opposing converging forming surfaces 54 that converge in a draw direction 56 along a bottom edge (root) 58 of the forming body. Molten glass delivered to forming body trough 52 via delivery vessel 40, exit conduit 44 and inlet conduit 50 overflows the walls of trough 52 and descends along the converging forming surfaces 54 as separate flows of molten glass. The separate flows of molten glass join below and along the root 58 to produce a ribbon 60 of molten glass that is drawn in draw direction 56 from root 58 by applying a downward tension to the glass ribbon, such as by gravity and/or counter-rotating and opposing pulling rolls. The downward tension and the temperature of the molten material can be used to control dimensions of the ribbon (hereafter glass ribbon) as the molten material cools and a viscosity of the material increases. Accordingly, glass ribbon 60 goes through a viscosity transition, from a viscous state to a viscoelastic state to an elastic state and acquires mechanical properties that give glass ribbon 60 stable dimensional characteristics. Glass ribbon 60 may be separated into shorter lengths, such as into glass sheets 62, by a glass separating apparatus 64. Alternatively, the glass ribbon may be spooled.
Components of downstream glass manufacturing apparatus 30, including any one or more of connecting conduits 32, 38, 46, fining vessel 34, mixing apparatus 36, delivery vessel 40, exit conduit 44, or inlet conduit 50 may be formed from a precious metal. Suitable precious metals include platinum group metals selected from the group consisting of platinum, iridium, rhodium, osmium, ruthenium and palladium, or alloys thereof. For example, downstream components of the glass manufacturing apparatus may be formed from a platinum-rhodium alloy including from about 70% to about 90% by weight platinum and about 10% to about 30% by weight rhodium.
For certain components of the glass manufacturing apparatus, particularly those metal components operated at high temperature, e.g., in excess of about 1300° C., for example in excess of 1400° C., in excess of about 1500° C., in excess of about 1600° C., or even in excess of about 1700° C., but less than the melting point of the metal component, structural integrity of the component may be compromised by the high temperature to which the component is subjected and the thinness of the component. That is, platinum, and other platinum group metals (and/or alloys thereof), are expensive. Accordingly, components incorporating these metals (e.g., including any one or more of connecting conduits 32, 38, 46, fining vessel 34, mixing apparatus 36, delivery vessel 40, exit conduit 44, or inlet conduit 50) are made with thin walls to reduce expense, e.g., having a thickness equal to or less than about 0.254 cm. Pure platinum, for example, has a melting temperature of 1768° C. In some optical-quality glass making apparatus, such as those intended for alumino-silicate glasses such as glass substrates used in the manufacture of optical display devices, a platinum-containing component may be operated in excess of 1600° C., or even in excess of 1700° C., very near the melting temperature of platinum. One such example is the fining vessel, a specialized metal conduit used to remove gases (e.g., bubbles) from the molten glass. The fining vessel is operated partially unfilled. That is, a gaseous atmosphere is maintained over a free surface of the molten glass, providing a region within the fining vessel where gases removed from the molten glass can accumulate and be vented from the fining vessel. However, at least because this gaseous atmosphere is less efficient at eliminating heat from the fining vessel than the molten glass in contact with the lower portion of the fining vessel, the upper portion of the fining vessel may become hotter than the lower portion. Additionally, the gaseous atmosphere provides less mechanical and/or hydraulic support than a comparable conduit completely filled with molten glass. Over time, gravity may cause the upper portion of the fining vessel to slump downward, narrowing the internal passageway of the fining vessel. This collapse can lead to increased resistance to the flow of molten glass through the fining vessel and possible structural failure thereof (e.g., a breach of the fining vessel). Other vessels, e.g., connecting conduits described herein, may also suffer from such outcomes for these or other reasons.
By way of example,
Previous attempts at supporting the upper portion of molten glass-conveying conduits has included metal tabs welded to the exterior of the conduit and anchored in supporting refractory material. However, these attempts did not prevent collapse, as placement of the tabs may not prevent collapse between tabs. Moreover, the tabs made movement of the conduit within the surrounding refractory due to thermal expansion and contraction difficult if not impossible, leading to stress failure of the conduit, and loss of refractory material due to a molten glass leaks can destroy the functionality of the tabs anchored therein. To mitigate collapse and extend the life of molten glass-conveying metal components, these components may be strengthened by adding reinforcing members as described herein below.
Referring now to
Electrical flanges 82 may be used to divide fining vessel 134, or any other conduit, into temperature zones, wherein the electrical current between adjacent electrical flanges can be controlled to obtain a predetermined temperature of the molten glass within the conduit between the adjacent flanges. As used herein, adjacent electrical flanges refers to a pair of electrical flanges wherein no additional electrical flange exists between the pair of adjacent flanges. However, one electrical flange may simultaneously serve as one of a first pair of adjacent electrical flanges and one of a second pair of adjacent electrical flanges. While two electrical flanges 82 are shown joined to fining vessel 134 in
Fining vessel 134 further comprises at least one reinforcing member 146 attached to an outer surface of fining vessel wall 136. The reinforcing member functions to support an upper portion of a conduit, for example a fining vessel, and prevent collapse of the conduit over an extended time at high operating temperatures. The at least one reinforcing member 146 may be a hollow metal tube attached to the fining vessel wall, such as by welding. The welding need not be continuous. For example, the at least one reinforcing member may be spot welded, or stitch welded, wherein spots or short sections of weld are separated by gaps in the weld. The reinforcing member may be orthogonal to a central longitudinal axis 148 of fining vessel 134 (see
The at least one reinforcing member 146 may extend partially or completely around the fining vessel. For example, assuming a fining vessel with a circular cross-sectional shape, in such a circumstance the at least one reinforcing member 146 may comprise a circular reinforcing member attached to the outer surface of fining vessel wall 136 that extends completely around fining vessel 134 (
As illustrated in
Alternatively, or in addition, the at least one reinforcing member 146 attached to fining vessel 134 may be a solid reinforcing member having a cross-sectional shape similar to or identical to the shapes described in respect of
To prevent over-pressurization of the at least one reinforcing member due to expansion of gas within a hollow interior of the reinforcing member, such as during heating up of fining vessel 134, the at least one reinforcing member 146 may be provided with one or more pressure equalization orifices 152, the one or more pressure equalization orifices extending between a hollow interior of the reinforcing member and the external atmosphere. Over-pressurization of the at least one reinforcing member 146 can result in bursting of the reinforcing member and damage to fining vessel 134. If the reinforcing member does not extend completely around the fining vessel, the reinforcing member may be open-ended, wherein the pressure equalization orifices may comprise the open ends of the tube or channel (where the reinforcing member comprises a U-shaped member, the pressure equalization orifices may comprise gaps in the weld if stitch or spot welding is used and the gaps in the weld extend between the hollow interior of the U-shaped member and the atmosphere outside the reinforcing member).
As shown in
The number and dimensional characteristics of the at least one reinforcing member 146 are dependent on the structural characteristics of the conduit (e.g., fining vessel 134) to which the at least one reinforcing member is attached. For example, the number and dimensional characteristics of the at least one reinforcing member 146 may depend on the length of the conduit, the thickness of the conduit wall or walls, the diameter of the conduit, the physical support provided to the conduit, either by anchors or other supporting structures such as refractory bricks or blocks, and the amount of deformation (e.g., downward displacement of the top of the conduit) that can be tolerated. As shown in
The at least one reinforcing member 146 may comprise a plurality of reinforcing members. For example, fining vessel 134 may have at least two reinforcing members attached thereto, such as three reinforcing members, four reinforcing members, five reinforcing members, six reinforcing members, or more than six reinforcing members. The plurality of reinforcing members 146 may be evenly spaced from one another, or unevenly spaced. There may be a first plurality of reinforcing members attached to the fining vessel between a first pair of adjacent electrical flanges 82, a second plurality of reinforcing members attached to fining vessel 134 between a second pair of adjacent electrical flanges 82, a third plurality of reinforcing members 146 attached to fining vessel 134 between a third pair of adjacent electrical flanges 82, and so forth.
Reinforcing members 146 disclosed herein are spaced apart from the electrical flanges and accordingly play little, if any, part in distribution of electrical current within fining vessel wall 136. Modeling has shown that the presence of reinforcing members spaced apart from electrical flanges do not affect electrical current density in the fining vessel wall and thus do not affect heat generation in the fining vessel wall.
While reinforcing members disclosed herein have been described primarily in terms of fining vessels, the disclosed reinforcing members 146, in all of their various shapes and arrangements, may be used on any metallic conduit configured to convey molten glass that may be subject to collapse, including whether or not electrical flanges may be present on the conduit. For example, any of the disclosed connecting conduits 32, 36, and 46 may be provided with reinforcing members 146.
It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.
This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 63/257,778, filed on Oct. 20, 2021, the content of which is relied upon and incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/044972 | 9/28/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63257778 | Oct 2021 | US |
