AU2008275267A1 - Pulling roll for the production of sheet glass - Google Patents

Pulling roll for the production of sheet glass Download PDF

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Publication number
AU2008275267A1
AU2008275267A1 AU2008275267A AU2008275267A AU2008275267A1 AU 2008275267 A1 AU2008275267 A1 AU 2008275267A1 AU 2008275267 A AU2008275267 A AU 2008275267A AU 2008275267 A AU2008275267 A AU 2008275267A AU 2008275267 A1 AU2008275267 A1 AU 2008275267A1
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AU
Australia
Prior art keywords
pulling
shaft
flat
center module
module
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
AU2008275267A
Inventor
Dwayne Bucko
Ryan Elliott
Hiroaki Inoue
Joseph Nardone
Akihiko Okada
Douglas Schlack
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vesuvius Crucible Co
Original Assignee
Vesuvius Crucible Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vesuvius Crucible Co filed Critical Vesuvius Crucible Co
Publication of AU2008275267A1 publication Critical patent/AU2008275267A1/en
Abandoned legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03BMANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/06Forming glass sheets
    • C03B17/068Means for providing the drawing force, e.g. traction or draw rollers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00Technologies relating to the processing of minerals
    • Y02P40/50Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57Improving the yield, e-g- reduction of reject rates

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)

Description

WO 2009/009477 PCT/US2008/069311 PULLING ROLL FOR THE PRODUCTION OF SHEET GLASS FIELD OF THE INVENTION [0001] This invention relates to the manufacture of sheet glass. More particularly, the invention relates to improved pulling rolls for use in controlling the thickness of glass produced by, for example, the overflow downdraw fusion process. The invention is of particular value in the production of high quality sheet glass, which exhibits low levels of surface defects. Such glass can be used as substrates for flat panel displays, e.g., liquid crystal displays. BACKGROUND OF THE INVENTION [0002] Pulling rolls are used in the manufacture of sheet glass to apply tension to the ribbon of glass from which the sheets are formed and thus control the nominal sheet thickness. For example, in the overflow downdraw fusion process (see Dockerty, U.S. Pat. Nos. 3,338,696 and 3,682,609), pulling rolls are placed downstream of the tip or root of the fusion pipe and are used to adjust the rate at which the formed ribbon of glass leaves the pipe and thus determine the nominal thickness of the finished sheet. The rolls are customarily used in pairs; the formed ribbon of glass is fed between the rolls. [0003] A frequently used configuration for such rolls comprises a profiled refractory cover over a steel shaft. A profiled cover is a cover that has portions with different radii with respect to the axis of the shaft. Pulling rolls are commonly designed to contact the glass ribbon at its outer edges, specifically, in regions just inboard of the thickened beads that exist at the very edges of the ribbon. The portion of the roll coming in contact with the glass ribbon is known as a pulling flat. The use of a roll with pulling flats minimizes the contact surface area between the pulling rolls and the glass, thereby minimizing damage to the glass sheet and the generation of wear debris from the rolls. [0004] A successful pulling roll needs to meet a number of conflicting criteria. First, the roll needs to be able to withstand the high temperatures associated with newly formed glass for substantial periods of time. The longer a roll can last in such an environment the better, since roll replacement reduces the amount of finished glass a given machine can produce and thus increases the ultimate cost of the glass. The roll must also be able to withstand any internal stresses generated by unequal heating, or by different coefficients of expansion that are exhibited by different portions of the roll being constructed of different materials. 1 WO 2009/009477 PCT/US2008/069311 [0005] Second, the roll must be able to produce enough pulling force to control the glass' thickness. In order not to damage the central portion of the ribbon that becomes the usable finished glass, the roll can only contact the ribbon over a limited area at its edges. Thus, the required pulling forces must be generated using only this area. However, the forces applied to the glass cannot be too large since this can create surface damage that can propagate into the usable central portion of the ribbon. Accordingly, the roll must achieve a balance between applying too little and too much force to the edge regions of the glass. [0006] Third, the pulling roll must not give off excessive amounts of particles that can adhere to the glass and form surface defects (known as "onclusions"). For glass that is to be used in such demanding applications as substrates for flat panel displays, onclusions must be kept to very low levels since each onclusion will typically represent a defective region of the finished product (e.g., one or more defective pixels). Because of the hot environment in which pulling rolls operate, finding materials which can apply sufficient pulling forces to a glass ribbon and yet not give off particles when hot is a difficult challenge. Work done previously in the field and the laboratory has established that when either a silica fiber or alumina silica fiber formed as a compressed cover on a shaft, impregnated with colloidal silica and fired to form a rigid body, is used in the application as the pulling roll cover media, clusters of colloidal silica particles and small amounts of fiber were the most prevalent form of dust and debris picked up by the convective currents, and transported up the draw to contaminate the surface of the sheet. [0007] The present invention addresses these shortcomings in the art and provides improved pulling rolls which achieve higher levels of performance than existing pulling rolls. SUMMARY OF THE INVENTION [0008] The roll of the present invention makes use of two or more materials in a roll configuration that provides a pulling flat containing a material optimized for glass contact, and remaining portions optimized for resistance to thermal and physical stress. One embodiment of the roll of the invention is made up of various components disposed co-axially about a shaft. These components are, in exterior view from one end of the shaft to another, a first end cap, a first end module, a first pulling flat, a center module, a second pulling flat, a second end module, and a second end cap. The modules and pulling flats may be generally cylindrical in form, with bores to accommodate the shaft. The modules and pulling flats are held in place on the shaft by such fastening means as end caps provided with compression fittings or with springs. The modules and pulling flats may be held in fixed positions relative 2 WO 2009/009477 PCT/US2008/069311 to each other by pins, screws, or other fasteners. In a variation on this embodiment, the pulling flats may take the form of cylinders with bores to accommodate, in addition to the shaft, the profile of either an end module or the center module, a reduced profile of either an end module or the center module, or reduced profiles or full profiles of an end module and a center module at opposite ends of the pulling flat bore. In this variation either or both of the center module and end modules serve as a support system for the pulling flat. The support system may be constructed of a compressible substance so as to absorb the diametrical expansion of the shaft while locking the pulling flat in place so that it cannot move on the shaft. The support system also serves as a stable platform to absorb the load applied to the pulling flat to pull the sheet of glass. The rolls of the invention may be configured so that they may be disassembled, fitted with replacement pulling flats, and reassembled. [0009] The pulling flat of the invention contains a TBS (thermally bonded shape). The TBS is constructed from a material that does not contain free colloidal silica or fibrous particles in a size range or shape that leads to fluidization of these particles in the convective currents produced in the sheet glass manufacturing process. The TBS may be a compressed pulling flat material such as a ceramic fiber felt formed from silicoalumina fiber that is produced through the blowing technique and washed to remove the shot. The washed silicoalumina fibers may then be dispersed into water slurry to which up to 4.5% by weight of a sodium-free solution of borate has been added. The resulting fiber suspension is then pressed until a compaction having the desired block density is obtained. This compaction is then fired at temperature at or about 1350'C to produce a ceramic body. The density of the block can be optimized to meet specific operating conditions. The TBS material has sufficient high temperature compressive strength to pull the glass. Any wear debris produced by the TBS material is not easily fluidized because of its combination of specific gravity, particle size and morphology. The TBS material is a sintered compressed product having a chemical bond between the colloidal component and the fiber, which eliminates the dust seen in rigidized materials in which the colloidal component is not bonded to the fiber but rather remains loose within the fiber matrix. [0010] Materials that may be used as the TBS material of the invention include TBS-N1, TBS-N2 and 1260TBS, available from Isolite Insulating Products Co., and having the following composition and characteristics: [0011] TBS-N1: Maximum temperature = 1200'C, density = 620 kg/m 3 , A1 2 0 3 content = 41.7 wt%, SiO 2 content: 53.8%, flexural strength = 11.9 Mpa, thermal expansion = 3.7 x 10-6 / K, thermal conductivity = 0.23 W/mK at 350'C. 3 WO 2009/009477 PCT/US2008/069311 [0012] TBS-N2: Maximum temperature = 1200'C, density = 950 kg/m, A1 2 0 3 content = 41.7 wt%, SiO2 content: 53.8%, flexural strength = 24.8 Mpa, thermal expansion = 3.7 x 10-6 / K, thermal conductivity = 0.37 W/mK at 350 C. [0013] 1260TBS: Maximum temperature = 1260'C, density = 550 kg/m, A1 2 0 3 content = 40.5 wt%, SiO2 content: 55.5%, flexural strength = 9.8 Mpa, thermal expansion = 3.7 x 10-6/ K, thermal conductivity = 0.14 W/mK at 350 C. [0014] The center module and the end modules are typically composed of fiber materials (such as the aluminosilicate fiber material commercially available as ZYALITE and the silicate fiber material available as ZYACIL) rigidized with colloidal-sized ceramic particles such as amorphous silica particles. End modules constructed of such rigidized fiber materials contain very hard surfaces that are resistant to wear and impact damage while simultaneously being resilient enough under the surface to be able to absorb the strain imparted by the thermal expansion of the shaft. These properties are imparted by making use of a coating material with a suitable particle size on a pre-form of the fiber material, by the method of application of the coating material to the pre-form and by the choice of an appropriate method of heat treatment. Application of a spray coating produces a roll that may be compressed and expanded. In one embodiment of the invention, the spray coating is applied to the center module and the end modules, but not to the pulling flats. Use of such rigidized fiber materials results in modules and rolls that are relatively lightweight. Suitable materials for these modules are described in U.S. Patents No. 5,205,398, 5,355,996 and 5,378,219, incorporated herein by reference. In one embodiment of the invention, the center module contains an aluminosilicate fiber material and the end modules contain a silica fiber material. [0015] In the embodiment of the invention in which the flat is underlain by a portion of the center module or an end module, the underlying portion provides for mechanical and physical support of the flat during the pulling of the sheet by a set of rolls. The underlying portion provides a stable platform to absorb the load exerted on the flat in the pulling process. The underlying portion also provides a compressive layer over the shaft and absorbs the diametric expansion of the shaft while locking the flat in place so that it cannot move in the shaft. In addition, as a result of their surface hardness, underlying portions of the center and end modules can prevent uneven wear of the flat due to slight variations on the density of the material from which the flat is constructed. [0016] The hard center module provides adequate support to the pulling flats, even at reduced profile, thereby allowing the main diameter of the center module to be reduced. This 4 WO 2009/009477 PCT/US2008/069311 increases the effective center gap between pairs of rollers which in turn allows wider sheets of glass to be pulled without touching the rollers at the center, thereby eliminating "micro-touch" defects near the center of the glass sheet. The hardness of the center module and the end modules results in extended service lives with respect to the pulling flats. [0017] Additional features and advantages of the invention are set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein. [0018] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as claimed. [0019] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0020] Fig 1 is a cross-section view of an apparatus according to the invention. DETAILED DESCRIPTION OF THE INVENTION [0021] The invention is best understood by reference to the accompanying drawing. It is emphasized that, according to common practice, the various dimensions of the apparatus and the associated component parts as shown in the drawings are not to scale and in some cases have been enlarged for clarity. [0022] Referring now to the drawing, shown in FIG. 1, is a pulling roll 10, containing a shaft 20 in the form of a cylinder, having two ends. Directions on the shaft towards the ends are designated "polar directions." Directions on the shaft towards the center of the shaft are designated "central directions." The shaft may be constructed of a metal such as stainless steel. Disposed coaxially around the shaft 20 is center module 22, having a cylindrical outer surface and two ends. Center module 22 has a bore to accommodate the shaft 20. Pulling flats 24 are disposed at either end of, and exterior to the cylindrical outer surface of, center module 22. Each pulling flat 24 has a cylindrical outer surface and two ends, a polar and a centrally directed end, in terms of their positions on the axis. Each pulling flat 24 has a bore to accommodate the profile of center module 22. Disposed coaxially around the shaft 20, and 5 WO 2009/009477 PCT/US2008/069311 in contact with either end of center module 22 and a polar end of a pulling flat 24, is an end module 26. Each end module 26 has a centrally directed end and a polar end. Each end module 26 has a bore to accommodate shaft 20. Disposed coaxially around the shaft 20, and in contact with a polar end of an end module 26, is an end cap 28. Each end cap 28 has a bore to accommodate shaft 20. A plurality of pins 32 fits into openings in a surface of center module 22, and aligned openings in the centrally directed surface of pulling flat 24. A plurality of pins 32 fits into openings in a polar surface of pulling flat 24, and aligned openings in the centrally directed surface of end module 26. End caps 28 may be fastened to the shaft 20 by any appropriate fastening means, such as by a spring or a compression fitting. Alternatively, the roll may be assembled without the use of pins 24; in this embodiment, mechanical linkage between the modules and pulling flats is provided by compressive force maintained by end caps 28 fastened to shaft 20, by other fasteners such as screws, or by providing the surfaces of the center module 22, pulling flats 24 and end modules with mating portions. [0023] The pulling flats 24 of the invention may comprise a thermal bonded shape produced by washing silicoalumina fiber, dispersing the silicoalumina fibers in water and sodium-free borate solution to form a suspension, pressing the suspension to form a compaction, and firing the compaction to achieve a ceramic body. The thermal bonded shape obtained by this process is a fired ceramic containing a reduced-shot or shot-free silicoalumina fiber chemically crosslinked to sodium-free borate. [0024] One example of a configuration for fastening an end cap 28 to shaft 20 is disclosed in U.S. Patent Publication No. 2002/265180 Al, the subject matter of which is incorporated herein by reference. [0025] Pulling roll 10 may be assembled by inserting the shaft 20 having two ends into a center module 22, inserting each end of shaft 20 into a respective pulling flat 24 so that each pulling flat 24 is provided with an exposed end and is engaged by the center module, inserting each end of shaft 20 into an end module 26 so that each pulling flat engages a respective end module 26, inserting each end of shaft 20 into a respective end cap 28, and securing each end cap 28 to shaft 20. The end caps 28 may be secured to shaft 20 with attachment devices such as spring or compression fittings. [0026] If pins are used in the assembly, pulling roll 10 may be assembled by inserting the shaft 20 having two ends into a center module 22, inserting at least one pin 32 into each end of center module 22, inserting each end of shaft 20 into a respective pulling flat 24 so that 6 WO 2009/009477 PCT/US2008/069311 each pulling flat 24 is provided with an exposed end and so that at least one pin 32 in center module 22 engages each of pulling flats 24, inserting at least one pin 32 into the exposed end of each pulling flat 24, inserting each end of shaft 20 into an end module 26 so that at least one pin 32 inserted into an exposed end of a respective pulling flat 24 engages a respective end module 26, inserting each end of shaft 20 into a respective end cap 28, and securing each end cap 28 to shaft 20. The end caps 28 may be secured to shaft 20 with attachment devices such as spring or compression fittings. [0027] Numerous modifications and variations of the present invention are possible. Within the scope of the following claims, the invention may be practiced otherwise than as specifically described. While this invention has been described with respect to certain preferred embodiments, different variations, modifications, and additions to the invention will become evident to persons of ordinary skill in the art. All such modifications, variations, and additions are intended to be encompassed within the scope of this patent, which is limited only by the claims appended hereto. 7

Claims (12)

1. A pulling roll comprising: a) a shaft; and b) a plurality of pulling flats, coaxially disposed on the shaft, wherein the pulling flats comprise a thermal bonded shape comprising a fired ceramic containing silicoalumina fiber chemically crosslinked to borate.
2. A pulling roll comprising: a) a shaft; b) a center module having a cylindrical outer surface and two ends, disposed coaxially on the shaft; c) a plurality of pulling flats having a cylindrical outer surface, disposed coaxially on, and at either end of, the cylindrical center module; d) a plurality of end modules, disposed coaxially on the shaft and in contact with an end of the center module; wherein the pulling flats comprise a thermal bonded shape comprising a fired ceramic containing silicoalumina fiber chemically crosslinked to borate.
3. The pulling roll of claim 2, wherein the center module and end modules comprise materials selected from the group consisting of aluminosilicate fiber materials and silica fiber materials.
4. The pulling roll of claim 3, wherein the center module comprises an aluminosilicate fiber material and the end modules comprise a silica fiber material.
5. The pulling roll of claim 2, wherein a pulling flat is underlain by a portion of the center module.
6. The pulling roll of claim 2, wherein a pulling flat is underlain by a portion of an end module.
7. The pulling roll of claim 2, wherein at least one pin inserted into the center module engages a pulling flat. 8 WO 2009/009477 PCT/US2008/069311
8. The pulling roll of claim 2, wherein at least one pin inserted into a pulling flat engages an end module.
9. A pulling flat for use in a pulling roll, comprising a fired ceramic containing silicoalumina fiber chemically crosslinked to borate.
10. A process for assembling a pulling roll, comprising: a) inserting a shaft having two ends into a center module, c) inserting each end of the shaft into a respective pulling flat, d) engaging each pulling flat to the center module, thereby producing an exposed end on each pulling flat, e) inserting each end of the shaft into a respective end module so that each exposed end of a respective pulling flat engages a respective end module, f) inserting each end of the shaft into a respective end cap; and g) securing each end cap to the shaft.
11. A process for assembling a pulling roll, comprising: a) inserting a shaft having two ends into a center module, b) inserting at least one pin into each end of the center module, c) inserting each end of the shaft into a respective pulling flat, d) engaging each pulling flat to at least one pin in the center module to provide each pulling flat with an exposed end, e) inserting at least one pin into the exposed end of each pulling flat f) inserting each end of the shaft into a respective end module so that the at least one pin inserted into the exposed end of a respective pulling flat engages a respective end module, g) inserting each end of the shaft into a respective end cap; and h) securing each end cap to the shaft.
12. The process of claim 10, wherein each of the two end caps is secured to the shaft with an attachment device selected from the group consisting of spring fittings and compression fittings. 9
AU2008275267A 2007-07-06 2008-07-07 Pulling roll for the production of sheet glass Abandoned AU2008275267A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US94831207P 2007-07-06 2007-07-06
US60/948,312 2007-07-06
PCT/US2008/069311 WO2009009477A1 (en) 2007-07-06 2008-07-07 Pulling roll for the production of sheet glass

Publications (1)

Publication Number Publication Date
AU2008275267A1 true AU2008275267A1 (en) 2009-01-15

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AU2008275267A Abandoned AU2008275267A1 (en) 2007-07-06 2008-07-07 Pulling roll for the production of sheet glass

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CN (1) CN101687319A (en)
AU (1) AU2008275267A1 (en)
BR (1) BRPI0813747A2 (en)
CA (1) CA2693119A1 (en)
WO (1) WO2009009477A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9388066B2 (en) 2013-05-31 2016-07-12 Corning Incorporated Glass forming apparatus and methods of forming glass ribbons
CN106325328B (en) * 2016-09-30 2018-04-13 深圳春沐源控股有限公司 A kind of method and device of planting equipment temperature adjustment
CN108046573A (en) * 2017-11-30 2018-05-18 彩虹(合肥)液晶玻璃有限公司 A kind of TFT-LCT glass substrate formings carry-over pinch rolls and preparation method thereof

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005520774A (en) * 2002-03-22 2005-07-14 コーニング インコーポレイテッド Tow roll used in the production of flat glass
EP1678098A1 (en) * 2003-10-20 2006-07-12 Vesuvius Crucible Company Non-dusting roll for tft glass
US8574358B2 (en) * 2005-12-06 2013-11-05 James Hardie Technology Limited Geopolymeric particles, fibers, shaped articles and methods of manufacture

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Publication number Publication date
CA2693119A1 (en) 2009-01-15
BRPI0813747A2 (en) 2014-12-30
CN101687319A (en) 2010-03-31
WO2009009477A1 (en) 2009-01-15

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MK1 Application lapsed section 142(2)(a) - no request for examination in relevant period