US20120004084A1 - Pulling Rolls for Making Sheet Glass and Methods of Making and Using - Google Patents

Pulling Rolls for Making Sheet Glass and Methods of Making and Using Download PDF

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Publication number
US20120004084A1
US20120004084A1 US12/829,685 US82968510A US2012004084A1 US 20120004084 A1 US20120004084 A1 US 20120004084A1 US 82968510 A US82968510 A US 82968510A US 2012004084 A1 US2012004084 A1 US 2012004084A1
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United States
Prior art keywords
temperature
millboard
pulling roll
time
weight loss
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
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US12/829,685
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English (en)
Inventor
Dean Veral Neubauer
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Corning Inc
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Corning Inc
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Assigned to CORNING INCORPORATED reassignment CORNING INCORPORATED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NEUBAUER, DEAN VERAL, MR
Priority to US12/829,685 priority Critical patent/US20120004084A1/en
Application filed by Corning Inc filed Critical Corning Inc
Priority to CN201180032835.XA priority patent/CN102971265B/zh
Priority to JP2013518706A priority patent/JP2013531607A/ja
Priority to PCT/US2011/042588 priority patent/WO2012003312A2/en
Priority to KR1020137002015A priority patent/KR101911104B1/ko
Priority to TW105114312A priority patent/TWI632118B/zh
Priority to TW100123366A priority patent/TWI614220B/zh
Publication of US20120004084A1 publication Critical patent/US20120004084A1/en
Priority to US14/611,794 priority patent/US9733021B2/en
Priority to JP2015153186A priority patent/JP6307478B2/ja
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B13/00—Rolling molten glass, i.e. where the molten glass is shaped by rolling
    • C03B13/16—Construction of the glass rollers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D99/00—Subject matter not provided for in other groups of this subclass
    • B29D99/0032—Producing rolling bodies, e.g. rollers, wheels, pulleys or pinions
    • B29D99/0035—Producing rolling bodies, e.g. rollers, wheels, pulleys or pinions rollers or cylinders having an axial length of several times the diameter, e.g. for embossing, pressing, or printing
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/06—Forming glass sheets
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/06—Forming glass sheets
    • C03B17/068—Means for providing the drawing force, e.g. traction or draw rollers
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49544—Roller making
    • Y10T29/49547—Assembling preformed components
    • Y10T29/49549—Work contacting surface element assembled to core
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49544—Roller making
    • Y10T29/49547—Assembling preformed components
    • Y10T29/49549—Work contacting surface element assembled to core
    • Y10T29/49554—Work contacting surface having annular axial sections

Definitions

  • the present disclosure relates to the manufacture of sheet glass. More particularly, the present disclosure relates to pulling rolls for use in the manufacture of sheet glass by, for example, the overflow downdraw fusion process.
  • 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.
  • 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.
  • Pulling rolls are preferably 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.
  • a preferred construction for such rolls employs discs of a heat resistant material, such as millboard, which are mounted on a driven shaft. Examples of this construction can be found in Moore, U.S. Pat. No. 3,334,010, Asaumi et al., U.S. Pat. No. 4,533,581, and Hart et al., U.S. Pat. No. 5,989,170, which are incorporated by reference in their entirety and for the specific purpose of describing examples of construction for pulling rolls.
  • a successful pulling roll can meet a number of conflicting criteria.
  • the roll should 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 should be able to produce sufficient pulling force to control glass thickness.
  • the roll 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 which can propagate into the usable central portion of the ribbon. Accordingly, the roll should achieve a balance between applying too little and too much force to the edge regions of the glass.
  • Damage to the surface of the glass sheet can also be caused by the wear characteristics of the pulling roll material and whether it has been damaged by particles of glass embedded in the surface of the roll.
  • the millboard material used in the construction of pulling rolls should also be hard enough to resist process damage due to broken glass during production for extended periods of time.
  • the pulling roll should not give off excessive amounts of particles, which can adhere to the glass and form surface defects known as onclusions.
  • onclusions For glass that is to be used in demanding applications, such 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, providing materials that can apply sufficient pulling forces to a glass ribbon and yet not give off particles when hot is a difficult challenge.
  • the present disclosure relates to pulling rolls for glass manufacture, and more particularly to a manner of preparing millboard materials used in the manufacture of pulling rolls. It is to be understood that various features of the invention disclosed in this specification and in the drawing can be used in any and all combinations. By way of non-limiting example the various features of the invention may be combined with one another as follows:
  • a pulling roll comprising a plurality of millboard pieces, wherein the plurality of millboard pieces have been fired at a predetermined temperature and time such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 5% upon exposure to operating temperatures.
  • the pulling roll of aspect 1 wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 3% upon exposure to operating temperatures.
  • the pulling roll of aspect 1 wherein the predetermined temperature and time are such that the pulling roll does not undergo a weight loss from thermal perturbations of more than 1% upon exposure to operating temperatures.
  • the pulling roll of any one of aspects 1-4 wherein the temperature and time are determined from a thermal profile of at least a portion of the plurality of millboard pieces.
  • the pulling roll of any one of aspects 1-5 wherein the plurality of millboard pieces have been fired at a temperature of at least about 750° C. for a period of at least about 4 hours.
  • the pulling roll of any one of aspects 1-5 wherein the plurality of millboard pieces have been fired at a temperature of at least about 900° C.
  • a method for manufacturing sheet glass comprising forming a ribbon of glass using a fusion process including contacting at least a portion of the ribbon of glass with the pulling roll of any one of aspects 1-7, and then separating a sheet of glass from the ribbon of glass.
  • a ninth aspect there is provided a method for preparing a pulling roll, the method comprising:
  • any one of aspects 9-12 wherein comprises heating at a temperature of at least about 750° C.
  • firing comprises heating at a first temperature and holding for a period of time, and then heating at a second temperature, wherein the second temperature is greater than the first.
  • any one of aspects 9-14 comprising prior to step a, determining the thermal profile of the millboard disks over at least an intended operational temperature range of the pulling roll.
  • the temperature is a temperature at which the plurality of millboard disks no longer lose weight from thermal perturbations upon exposure to the operational temperature range of the puling roll.
  • a method for determining a heating program for a millboard material comprising:
  • step b comprises determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 3% upon exposure to the operating temperature.
  • step b comprises determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 1% upon exposure to the operating temperature.
  • any one of aspects 17-19 further comprising firing a plurality of millboard pieces at the determined temperature and time.
  • any one of aspects 17-20 further comprising assembling the plurality of millboard pieces, after firing, to form a pulling roll.
  • any one of aspects 17-20 further comprising assembling the plurality of millboard pieces, prior to firing, to form a pulling roll and then firing the pulling roll at the temperature and for the time.
  • the present disclosure provides a method for determining a heating program for a millboard material, the method comprising monitoring the weight of a portion of the millboard material while heating at about ambient to at a temperature higher than an expected pulling roll operating temperature (for example, for Nichias SD-115 material, such a temperature may be 1000° C. or higher), and then determining the temperature and time at which the millboard material should be fired such that a pulling roll formed from the millboard material does not undergo a weight loss from thermal perturbations of more than 5% upon exposure to the operating temperature.
  • an expected pulling roll operating temperature for example, for Nichias SD-115 material, such a temperature may be 1000° C. or higher
  • FIG. 1 is exemplary data from thermogravimetric analysis and differential thermal analysis of a millboard material.
  • the x-axis represents temperature in ° C.
  • left y-axis represents the percentage decrease in mass
  • the right y-axis axis represents the derivative or variation of mass/temperature.
  • the top line in the FIGURE illustrates the derivate curve, as can be obtained by Differential Thermal Analysis
  • the decreasing bottom curve illustrates the weight loss from Thermogravimetric Analysis.
  • 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 aspect includes from the one particular value and/or 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 aspect. 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.
  • wt. % or “weight percent” or “percent by weight” of a component, unless specifically stated to the contrary, is based on the total weight of the composition in which the component is included.
  • weight loss is intended to refer to a loss in weight of a millboard material and/or a pulling roll comprising a millboard material, the weight loss occurring as a result of thermal perturbations of the millboard material and/or pulling roll, for example, during use.
  • weight loss is intended to include, but is not limited to weight loss resulting from the combustion and/or volatilization of components (for example, functional components and/or impurities) in the millboard material and/or pulling roll upon exposure to, for example, operating temperatures.
  • the term “weight loss” is not intended to refer to weight loss occurring from purely mechanical perturbations, such as, for example, physical wear.
  • thermal profile is intended to refer to the weight characteristics of a material upon exposure to either a fixed temperature for a specified time or a temperature gradient at a constant or varying rate.
  • a thermal profile can indicate at what temperature a material will lose weight, for example, due to combustion and/or volatilization, the rate of weight loss at a given temperature, and/or the time needed to reach a stable weight at a given temperature.
  • the temperature or temperature range over which a thermal profile is obtained can vary depending upon, for example, the intended use of the material.
  • the present disclosure provides a pulling roll that can, for example, significantly reduce onclusions in a sheet glass manufacturing process.
  • the present disclosure also provides methods for preparing and using a pulling roll.
  • the pulling roll of the present disclosure can exhibit a longer lifespan or operation time to failure, when compared to conventional pulling rolls.
  • the inventive pulling roll can enable the production of glass with significantly fewer onclusions or defects than conventional pulling rolls.
  • the methods of the present disclosure comprise firing a millboard material at a predetermined temperature and for a predetermined time so as to prevent weight loss due to thermal perturbations from occurring during use and/or exposure to operating temperatures.
  • a pulling roll for use in the manufacture of sheet glass, can be produced from a millboard material, as described above.
  • the millboard can be cut into pieces, fired, and the pieces then mounted on a shaft in face-to-face contact.
  • the outer surface of each can form a portion of the exterior surface of the pulling roll.
  • At least a portion of the exterior surface of the pulling roll can be adapted to contact the glass sheet.
  • the portion of the pulling roll adapted to contact the glass sheet typically has a Shore D hardness at room temperature of between 30 and 60, preferably between 40 and 55.
  • a pair of pulling rolls engage a glass sheet formed by an overflow downdraw process, wherein at least a portion of the outer surface of the pulling rolls contacts the glass sheet.
  • a pulling roll can also include a shaft, which can carry a plurality of millboard pieces held in place by collars that can apply an axial compressive force to the millboard pieces when affixed to the shaft.
  • An assembled pulling roll can include a bearing surface positioned on at least one end of the shaft.
  • a pulling roll can also include a portion specifically adapted for contacting a glass sheet, wherein the exterior surface of the pulling roll at that portion extends a further distance from the shaft than does the surrounding portion of the pulling roll.
  • the pulling roll of the present disclosure can comprise any millboard material suitable for use in forming a pulling roll.
  • Millboard materials are often used as thermal insulation materials in various industries, including glass manufacture.
  • Millboard articles are typically produced by creating a slurry of the desired components, using a rotating screened cylinder to effect uptake and dewatering of the components, transferring the dewatered components to a synthetic felt and then to an accumulator roll, where layers of the slurry are accumulated upon one another to a desired thickness. These accumulated layers can be slit, removed, and formed into flat sheets of desired dimensions for subsequent use.
  • a millboard sheet can be compressed by rollers to give it a uniform thickness. The resulting millboard sheet can subsequently be heated to remove residual moisture.
  • a pulling roll can comprise a commercially available millboard material, such as, for example, Nichias SD-115.
  • a pulling roll can comprise a millboard comprised of an aluminosilicate refractory fiber, a silicate, a mica, a kaolin clay, and other optional functional components such as cellulose, starch, or silica.
  • a pulling roll can comprise a millboard material having a different composition than those specifically recited here, and the present invention is not intended to be limited to any particular millboard composition.
  • a millboard composition has a temperature resistance of greater than about 800° C., preferably greater than about 1,000° C.
  • the compressibility of a pulling roll is dependent upon the density of the millboard pieces from which the pulling roll is formed. It is desirable that a pulling roll, and thus the millboard material, exhibit low compressibility, for example, between about 15 and about 30 percent at 25° C., and/or less than about 5 percent at about 110° C. It is also desirable that a millboard material exhibit high recovery, for example, greater than about 30 percent, preferably greater than about 50 percent, and more preferably greater than about 60 percent. In one aspect, a millboard material has a recovery of at least about 30 percent, preferably at least about 50 percent, or more preferably at least about 60 percent at a high temperature, such as a temperature to which a pulling roll would be exposed during operation, for example, about 750° C.
  • a millboard material has a recovery of at least about 50 percent at a temperature of at least about 750° C. Millboard materials possessing such recovery percentages can expand upon removal of the axial compressive force placed on a pulling roll or upon elongation of the pulling roll shaft as a result of thermal expansion, thus preventing separation of the millboard pieces that form the pulling roll.
  • Weight loss on a pulling roll, during operation can occur from, for example, combustion and/or volatilization of components in the millboard material comprising the pulling roll which, in turn, may form onclusions in the glass produced with that pulling roll as the combustion and/or volatilization occurs.
  • these combustible and/or volatile components can comprise functional materials, such as cellulose, that can be easily combusted in a firing step.
  • Weight loss can be different from a change in composition or dimension. For example, weight loss can occur in a material without changing its composition and/or dimension when it is fired to 100° C.
  • weight loss can also result in separation of the disks of millboard material, especially when coupled with thermal expansion of the pulling roll shaft. Even relatively small weight losses can be significant in the performance and lifespan of a pulling roll. For example, a weight loss of about 1.5% during operation can be equivalent to about 4 disks of millboard material on a fully covered 65 inch pulling roll, about 7 disks of millboard material on a 98 inch pulling roll, and about 11 disks on a 143 inch pulling roll.
  • composition and/or dimension change can occur without a change in weight when the material increases in shrinkage with an increase in temperature, reducing the volume occupied by the same weight, which also ahs the effect of increasing the density.
  • the methods of the present disclosure comprise firing a millboard material at a predetermined temperature and for a predetermined time so as to prevent weight loss due to thermal perturbations from occurring during use and/or exposure to operating temperatures.
  • the predetermined temperature and time are obtained from a thermal profile of the millboard material. In another aspect, the predetermined temperature and time are sufficient to prevent weight loss from thermal perturbations during use or exposure to operating temperatures. In yet another aspect, the predetermined temperature and time are such that the millboard material and/or a pulling roll made therefrom does not undergo a weight loss of more than 5% as a result of thermal perturbations upon exposure to operating temperatures. In still other aspects, the predetermined temperature and time are such that the millboard material and/or a pulling roll made therefrom does not undergo a weight loss of more than 4%, more than 3%, more than 2%, more than 1.5%, more than 1%, or more than 0.5%, as a result of thermal perturbations upon exposure to operating temperatures. In still other aspects, the percentage weight loss of a millboard material and/or a pulling roll made therefrom can vary, provided that glass produced from the pulling roll has a significantly reduced onclusion rate as compared to that produced from a conventional pulling roll.
  • the millboard material is fired prior to assembly of a pulling roll so that the millboard material exhibits substantially no weight loss when exposed to the temperatures at which the rolls (produced from those millboard pieces) operate.
  • the desired temperature and time for firing a millboard material can be determined by, for example, a thermal profile of the millboard material reflecting the weight loss of the material with respect to time and/or temperature.
  • a thermal profile can be ascertained is through the use of thermogravimetric analysis, wherein the mass of a millboard material is monitored as it is subjected to a temperature gradient.
  • Thermogravimetric analysis is an analytical technique that measures the weight loss (or weight gain) of a material as a function of temperature. As the material is heated, it can lose weight from drying, or from, for example, chemical reactions that liberate gasses. Some materials can gain weight by reacting with the atmosphere in the testing environment, such as a kiln.
  • phase transitions dehydration, and decomposition, redox, or solid-state reactions.
  • any phase changes that occur can be identified at the temperatures they occur.
  • An understanding of any such phase changes, such as reactions in progress before the thermal profile is complete and those desirable at operating temperatures and beyond (even though no further weight loss is observed at a lower temperature), can be important.
  • the FIGURE shows the differential thermal analysis as the derivative curve.
  • a reaction resulting in a phase change shows a dip in the curve at the temperature at which it occurs. For example, at 100° C., a dip occurs due to water being driven off. At 300° C., a dip occurs when organic components such as starch and cellulose are burned off. At 520° C., a dip occurs when the clay in the millboard reacts with other components.
  • a thermal profile can be acquired under the same or similar environmental conditions, for example, air or inert atmosphere, as can be expected during operation of a pulling roll.
  • a thermal profile can indicate the temperature(s) at which a millboard material loses weight, for example, due to combustion and/or volatilization of components within the millboard material.
  • a thermal profile can indicate the rate of weight loss at a temperature or over a temperature range, or the time required to completely or substantially combust and/or volatilize components in the millboard material.
  • FIG. 1 An exemplary thermal profile for a Nichias SD-115 millboard material is depicted in the FIGURE. As illustrated in the FIGURE, the millboard material loses weight over several distinct ranges around about 100° C., 300° C., and 520° C., and then gradually over the range of from about 550° C. to about 850° C. No further weight loss is apparent above about 900° C., as indicated by the flat line.
  • a thermal profile can be acquired over the temperature range from ambient up to (and beyond) about the operating temperature of a pulling roll.
  • the operating temperature can vary, depending on, for example, the specific type and dimensions of glass being produced.
  • a thermal profile can be acquired over a temperature range greater than the operating temperature of a pulling roll so as to account for otherwise unexpected increases in operating temperature. For example, if the intended operating temperature of a pulling roll is about 750° C., it may be advantageous to understand how the millboard material behaves upon exposure to temperatures greater than 750° C. In such an example, a millboard material may continue to lose weight up to about 800° C. Thus, firing of the millboard material at only 750° C. can, in various aspects, leave combustible and/or volatile material within the millboard material that can cause problems during unintended temperature variations (e.g., spikes) during operation.
  • a millboard material may lose weight only over a temperature range less than an intended operating temperature.
  • a pulling roll may have an intended operating temperature of about 1,000° C., but the millboard material comprising the pulling roll may only lose weight over the range of from about 650° C. to about 800° C.
  • firing the millboard material to the intended operating temperature of about 1,000° C. may be unnecessary and result in wasted energy, increased cost, and manufacturing time.
  • the predetermined temperature and time at which a millboard material should be fired is sufficient to prevent further weight loss due to thermal perturbations during use.
  • the predetermined temperature and time at which a millboard material should be fired is the minimum temperature and time necessary to reach a stable weight, up to about the operating temperature.
  • the temperature and time at which a millboard material should be fired can be determined by identifying the temperature at which only the minimally acceptable weight loss will occur upon exposure to operating temperatures. For example, with reference to the FIGURE, if the expected operating temperature is up to about 760° C., and if a weight loss of about 0.5% is acceptable, the millboard material can be fired at about 700° C.
  • the millboard material should be fired at least at a temperature of about 760° C., preferably at a temperature higher than about 760° C. (as there is further weight loss above 760° C., and so as to account for unexpected temperature variance), further preferably at a temperature of about 900° C.
  • the time at which a millboard material is fired can be determined from a thermal profile by varying the heating rate and/or heating at a fixed temperature to monitor weight loss with respect to time.
  • the length of time at which a millboard material should be fired or held at a predetermined temperature can be dependent on the thermal mass of the millboard material.
  • the various methods of the present disclosure provide a mechanism to determine the desired firing time and temperature.
  • these methods can provide improved pulling roll performance by eliminating problems resulting from weight loss during use, along with reduced waste of time and energy.
  • a millboard can be analyzed and/or subjected to temperatures that may be encountered during glass manufacture, such as, for example, from about 600° C. to about 1,000° C. or more.
  • the material weight loss behavior as a function of temperature can be understood prior to fabrication of the pulling roll.
  • the thermal profile and thus, the desired temperature and time for firing a millboard material can vary based on, for example, the millboard composition, impurities, specific production lot, and other environmental factors. It should also be understood that the thermal profile of a given millboard material can change over time. Thus, in one aspect, the thermal profile of each lot or type of millboard material advantageously can be ascertained prior to fabrication of a pulling roll.
  • disks of millboard material are fired prior to assembly on a pulling roll.
  • a millboard material can be fired (prior to assembly into a pulling roll) at a temperature and for a time sufficient to eliminate or minimize any further weight loss at the expected pulling-roll operating temperature. Firing at such a temperature and for such time will ensure that the pulling roll will not lose weight or bulk density once placed in production.
  • the millboard material can be fired at a temperature of at least about 900° C. and held for a period of time such that no further weight loss occurs.
  • a period of time can comprise at least about two hours, at least about 3 hours, at least about 4 hours, or at least about 5 hours.
  • the period of time comprises at least about 4 hours.
  • the millboard material can be fired at a first temperature and held for a period of time, such that substantially all of the weight loss occurs.
  • a millboard material can be fired at a temperature of from about 700° C. to about 760° C. and held for a period of time.
  • the millboard material can then be heated at a higher second temperature and held for a period of time.
  • a second temperature can be at least about 800° C., at least about 900° C., or at least about 1,000° C.
  • firing can occur in a single step (e.g., heating by ramping furnace temperature directly at a single temperature) or in multiple steps (e.g., two or more steps wherein the material is fired at a first temperature and held for a period of time, then fired at a second temperature and held for a second period of time, and so forth).
  • the rate at which a millboard material (either as part of a pulling roll or before assembly into a pulling roll) is heated for a firing step can be any rate suitable for use in preparing the millboard material.
  • the specific rate at which a millboard material is heated is not important, and any rate can be utilized.
  • the rate at which a millboard material is heated can comprise any rate or combination of rates, provided that no or substantially no phase change occurs over the temperature range being used to fire the millboard material. If there is a phase change that occurs over the temperature range used to fire the millboard material, then it may be advantageous to hold the material at a particular temperature and for a particular time to allow the phase change to occur before heating at a higher temperature.
  • the rate at which a millboard material can be heated can comprise any rate that provides sufficient time for the combustion and/or volatilization of components in the millboard material to occur.
  • the combustible and/or volatile components are removed and are not trapped within the millboard material where they could subsequently be combusted or volatilized during use.
  • the millboard can be heated at a rate of from about 50° C./hr to about 150° C./hr, such as, for example, about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, or 150° C./hr; or from about 80° C./hr to about 120° C./hr, for example, about 80, 85, 90, 95, 100, 105, 110, 115, or 120° C.
  • the millboard can be heated at a rate of about 100° C./hr.
  • the millboard can be heated at a rate of less than about 50° C./hr or greater than about 150° C./hr, and the present disclosure is not intended to be limited to any particular heating rate.
  • the millboard material After firing, the millboard material can be cooled or allowed to cool to a temperature at which it can be safely handled and/or placed on a pulling roll shaft.
  • An appropriate number of fired millboard disks can be placed on a pulling roll shaft and pressed so that a locking mechanism, such as a collar with a set of snap rings, can be applied to hold the disks in compression. This pressed shaft can then be cut to desired dimensions prior to installation and use.
  • a locking mechanism such as a collar with a set of snap rings
  • millboard material can be assembled into a pulling roll or portion thereof either prior to firing, after firing, or after partial firing, such that, for example, some weight loss can still occur due to thermal perturbations at operating temperatures.
  • the millboard material can be fired prior to assembly such that no or substantially no weight loss due to thermal perturbations occurs during operation. If the pulling roll is first heated at a temperature within the operating range during operation, as opposed to heating until there is no weight change over the expected operating temperature range of the pulling roll, onclusion defects may be produced in the glass as material burns out of the pulling roll. Additionally, by firing the millboard material prior to fabrication of the pulling roll, material shrinkage will be eliminated, and the resulting pulling roll will maintain its bulk density and hardness. The resulting pulling roll will also exhibit longer life and be more resistant to damage from glass particles.
  • a pulling roll formed with millboard material that has been fired in accordance with the various methods described herein, i.e., so that the millboard material does not change weight due to thermal considerations when heated at a temperature within the expected operating range of the pulling roll can provide a significant reduction in the level of onclusions over conventional pulling rolls. In various aspect, such reductions can be up to about 30%, 40%, 50%, 60%, 70%, or more. In a specific aspect, a pulling roll prepared with millboard material that has been fired as described herein can provide, for example, a 68% reduction in onclusions.
  • an onclusion rate of about 6.5% when using a conventional pulling roll can be reduced to about 3.9% when using a pulling roll formed with millboard materials fired—as described herein—prior to assembly into the pulling roll. Depending on the specific location of a particular pulling roll, this level can be further reduced to about 2.0%.
  • the use of rolls formed as described in the present disclosure can, in various aspects, greatly reduce onclusions with respect to a conventional roll.
  • the disks on a conventional roll would lose weight and therefore produce particles and/or debris since the operating temperature can be higher than the temperature seen during fabrication.
  • the likelihood of further weight loss and onclusions during use is reduced or eliminated for pulling rolls in the highest production position.
  • Such a technique can also ensure that the fabricated pulling roll bulk density remains virtually unchanged, thereby extending roll life.
  • Pulling rolls produced according to the various methods of the present disclosure have the advantage, in one aspect, of not producing onclusions from combustion and/or volatilization of components in the millboard material. Such pulling rolls can also ensure that the fabricated roll bulk density remains virtually unchanged, extending roll life.
  • a commercially available millboard material (Nichias SD-115) was subjected to thermogravimetric analysis to determine the amount of weight loss that occurs over the projected operating temperature range of a pulling roll.
  • the millboard material lost weight when heated at a temperature of about 100° C., 300° C., and 520° C., with approximately 15.2 wt. % being lost over the furnace-temperature range of ambient to 700° C.
  • the furnace temperature Upon raising the furnace temperature from 700° C. to 900° C., the millboard material lost an additional 1.5 wt. %.
  • the desired maximum firing temperature for this material is selected to be 900° C.
  • the weight loss would be 0.5% of its weight as shown in the FIGURE. If another pulling roll made from material was fired at a temperature of 700° C. and the pulling roll was exposed to an operating temperature of 900° C. or more, then the weight loss would be 1.5% of its weight as shown in the FIGURE.
  • Such a weight loss can result in damage to the pulling roll and onclusions in the produced glass. In the latter case, the pulling rolls would be expected to produce three times as many onclusions as the former case pulling rolls.
  • the millboard material can be fired at the highest temperature at which weight is lost, up to, and beyond, about the intended operating temperature, for example, about 900° C., and held until no further weight loss is observed, thus preventing weight loss during use.
  • a plurality of Nichias SD-115 millboard pieces suitable for forming a pulling roll can be subjected to a predetermined temperature program, based on the results obtained in Example 1.
  • the millboard material can be heated at a first temperature of about 760° C. by raising the furnace temperature from ambient at a heating rate of about 100° C./hr, and then held for a period of time.
  • the millboard can subsequently be heated at a second temperature of about 900° C. and held for about 4.75 hrs, again, raising the temperature of the furnace at a rate of about 100° C./hr.
  • the heated millboard material can then be allowed to cool slowly such that it can be handled and removed safely.
  • a plurality millboard pieces suitable for forming a pulling roll can be subjected to a predetermined temperature program, based on a previously acquired thermal profile that indicates that weight loss can occur over the temperature range of about 700° C. to 850° C.
  • a millboard material can be heated at a furnace temperature from ambient to about 900° C. and held for a period of time sufficient to prevent further weight change of more than 1% upon exposure to operating temperatures, for example, a sufficient time may be about 4 to 5 hours. After holding at 900° C. for 4 to 5 hours, the millboard material can be cooled or allowed to cool such that it can be handled.
  • a pulling roll was manufactured with Nichias SD-115 millboard material that had been heated at about 900° C. for about 4 hours.
  • the onclusion rate was about 3.9%, as compared to an average of about 6.5% for a conventional pulling roll.
  • the #1 position is situated just below the tip or root of the fusion pipe and is used to establish the glass ribbon at the beginning of a production run or after a process upset which causes the ribbon to break upwards towards the tip or root of the fusion pipe. Rolls used in this position experience the hottest operating temperatures and the potential for onclusions is the greatest if the firing temperature of the material is below these operating temperatures.
  • the #2 position is situated just below the #1 position and once the glass ribbon is established with the rolls in the #1 position they are placed on the ribbon but contact the glass outside the usable central portion of the ribbon and so are used for pulling the ribbon through the process. Rolls used in this position experience lower operating temperatures than those used in the #1 position, but there is still the potential for onclusions if the firing temperature of the material is below these operating temperatures. Also, since these rolls contact the glass during production of usable glass sheet any onclusions produced from roll wear can cause the rejection of manufactured glass sheets. If the rolls are fired at a temperature at which no weight loss occurs, they will not change in bulk density upon installation and will not wear as quickly as rolls fired at lower temperatures, so the potential for onclusions as a result of roll wear is much lower.
  • the #4 position (and lower positions) is situated well below the rolls in the #2 position and are generally used to guide instead of pull the glass ribbon. Rolls in this position (and lower positions) experience much lower operating temperatures that are generally below the firing temperature; however, onclusions from roll wear can remain a concern. If the rolls are fired at a temperature at which no weight loss occurs, they should not change in bulk density upon installation and will not wear as quickly as rolls fired at lower temperatures. Thus, the potential for onclusions as a result of roll wear is much lower.
  • the pulling rolls made according to the concepts discussed herein can achieve an improvement in pulling roll lifetime of about 30-60 days.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Glass Compositions (AREA)
US12/829,685 2010-07-02 2010-07-02 Pulling Rolls for Making Sheet Glass and Methods of Making and Using Abandoned US20120004084A1 (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US12/829,685 US20120004084A1 (en) 2010-07-02 2010-07-02 Pulling Rolls for Making Sheet Glass and Methods of Making and Using
CN201180032835.XA CN102971265B (zh) 2010-07-02 2011-06-30 用于制备片状玻璃的牵拉辊及其制备和使用方法
JP2013518706A JP2013531607A (ja) 2010-07-02 2011-06-30 板ガラス作製用牽引ローラと、これを作製および使用する方法
PCT/US2011/042588 WO2012003312A2 (en) 2010-07-02 2011-06-30 Pulling rolls for making sheet glass and methods of making and using
KR1020137002015A KR101911104B1 (ko) 2010-07-02 2011-06-30 시트 유리를 제조하는 풀링 롤，이에 대한 제조 방법 및 사용 방법
TW105114312A TWI632118B (zh) 2010-07-02 2011-07-01 用於製備拉引滾輪之方法
TW100123366A TWI614220B (zh) 2010-07-02 2011-07-01 用以製造板狀玻璃之拉引滾輪及製造與使用方法
US14/611,794 US9733021B2 (en) 2010-07-02 2015-02-02 Pulling rolls for making sheet glass and methods of making and using
JP2015153186A JP6307478B2 (ja) 2010-07-02 2015-08-03 板ガラス作製用牽引ローラと、これを作製および使用する方法

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JP (2) JP2013531607A (enExample)
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US20120298476A1 (en) * 2008-09-17 2012-11-29 Nichias Corporation Heat-resistant roll, production method thereof, and method of producing sheet glass using heat-resistant roll
US20150307384A1 (en) * 2014-04-24 2015-10-29 Corning Incorporated Glass manufacturing apparatus and methods
USRE46010E1 (en) * 2002-03-22 2016-05-24 Corning Incorporated Method for producing pulling rods for use in manufacturing sheet glass
US9733021B2 (en) 2010-07-02 2017-08-15 Corning Incorporated Pulling rolls for making sheet glass and methods of making and using
US20180301248A1 (en) * 2015-10-15 2018-10-18 Sumitomo Electric Industries, Ltd. Oxide superconducting wire
US10808666B2 (en) 2015-10-07 2020-10-20 Vitesco Technologies GmbH High-pressure fuel pump and fuel supply device for an internal combustion engine, in particular of a motor vehicle
CN112939428A (zh) * 2021-03-12 2021-06-11 成都中光电科技有限公司 一种牵引辊及其预处理方法

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CN106830633B (zh) * 2017-02-09 2021-03-02 东旭光电科技股份有限公司 牵引辊的加工方法
CN111792820B (zh) * 2020-06-24 2022-12-23 江苏太平洋石英股份有限公司 连熔法生产大尺寸石英玻璃板工艺、石英玻璃板及其应用

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USRE46010E1 (en) * 2002-03-22 2016-05-24 Corning Incorporated Method for producing pulling rods for use in manufacturing sheet glass
US20120298476A1 (en) * 2008-09-17 2012-11-29 Nichias Corporation Heat-resistant roll, production method thereof, and method of producing sheet glass using heat-resistant roll
US9604867B2 (en) * 2008-09-17 2017-03-28 Nichias Corporation Heat-resistant roll, production method thereof, and method of producing sheet glass using heat-resistant roll
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US20180301248A1 (en) * 2015-10-15 2018-10-18 Sumitomo Electric Industries, Ltd. Oxide superconducting wire
CN112939428A (zh) * 2021-03-12 2021-06-11 成都中光电科技有限公司 一种牵引辊及其预处理方法
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KR20130130679A (ko) 2013-12-02
JP2016020300A (ja) 2016-02-04
US20150143698A1 (en) 2015-05-28
TW201208992A (en) 2012-03-01
TWI632118B (zh) 2018-08-11
CN102971265B (zh) 2016-09-28
TWI614220B (zh) 2018-02-11
WO2012003312A3 (en) 2012-04-05
TW201641454A (zh) 2016-12-01
KR101911104B1 (ko) 2018-10-23
CN102971265A (zh) 2013-03-13
US9733021B2 (en) 2017-08-15
JP2013531607A (ja) 2013-08-08
WO2012003312A2 (en) 2012-01-05

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