WO2017204526A1 - Glass manufacturing apparatus and method - Google Patents

Glass manufacturing apparatus and method Download PDF

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Publication number
WO2017204526A1
WO2017204526A1 PCT/KR2017/005340 KR2017005340W WO2017204526A1 WO 2017204526 A1 WO2017204526 A1 WO 2017204526A1 KR 2017005340 W KR2017005340 W KR 2017005340W WO 2017204526 A1 WO2017204526 A1 WO 2017204526A1
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WO
WIPO (PCT)
Prior art keywords
draw
roll
draw roll
driving current
driving
Prior art date
Application number
PCT/KR2017/005340
Other languages
French (fr)
Other versions
WO2017204526A8 (en
Inventor
Yongjae JEONG
Yeonjin Kim
Jinkon LEE
Jukwang LEE
Kyungho Namkoong
Original Assignee
Corning Precision Materials Co., Ltd.
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 Corning Precision Materials Co., Ltd. filed Critical Corning Precision Materials Co., Ltd.
Priority to JP2018561216A priority Critical patent/JP2019516660A/en
Priority to CN201780031688.1A priority patent/CN109641773A/en
Publication of WO2017204526A1 publication Critical patent/WO2017204526A1/en
Publication of WO2017204526A8 publication Critical patent/WO2017204526A8/en

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    • 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
    • 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
    • C03B17/064—Forming glass sheets by the overflow downdraw fusion process; Isopipes therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/02—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor
    • C03B33/0215—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor the ribbon being in a substantially vertical plane
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping

Definitions

  • the present disclosure generally relates to a glass manufacturing apparatus and method. More particularly, the present disclosure relates to a glass manufacturing apparatus and a method for manufacturing a glass sheet by drawing a glass ribbon using at least one pair of draw rolls.
  • a fusion process (e.g. an overflow downdraw process) is known as a method of forming thin, high-quality glass sheets that can be used in a variety of devices, such as flat panel displays.
  • the fusion process is a preferred technique for producing glass sheets used in flat panel displays because glass sheets produced thereby have superior surface flatness and smoothness when compared to glass sheets produced using other methods.
  • Various aspects of the present disclosure are intended to reduce a difference in draw conditions of matching draw rolls and/or to compensate for a difference in amounts of wear of the matching draw rolls, thereby manufacturing a glass ribbon having superior quality.
  • a method of manufacturing a glass ribbon may include:
  • a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
  • a method of manufacturing a glass ribbon may include:
  • a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
  • a method of assessing drawing conditions may include:
  • a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet in a first drawing condition and the second draw roll rotates to draw the other surface of the sheet in a second drawing condition;
  • a method of assessing amounts of wear of draw rolls may include:
  • a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet and the second draw roll rotates to draw the other surface of the sheet;
  • a method of manufacturing a glass ribbon may include:
  • a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device driving the first draw roll and a second driving device driving the second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
  • a glass manufacturing apparatus may include:
  • a forming device configured to form a glass ribbon having a width
  • a pull roll device configured to draw the glass ribbon along a draw path extending transverse to the width from the forming device, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll;
  • a control device configured to:
  • the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
  • a pull roll apparatus may include:
  • a pull roll device configured to draw a glass ribbon having a width along a draw path extending transverse to the width, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll;
  • a control device configured to:
  • the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
  • FIG. 1 is a schematic illustration of a glass manufacturing apparatus used to manufacture a glass sheet according to an exemplary embodiment
  • FIG. 2A to FIG. 2C are schematic illustrations of a pull roll apparatus according to a first exemplary embodiment
  • FIG. 3 is schematic illustration of a pull roll apparatus according to a second exemplary embodiment
  • FIG. 4 is a schematic illustration of a pull roll apparatus according to a third exemplary embodiment
  • FIG. 5 is a schematic illustration of a pull roll apparatus according to a fourth exemplary embodiment
  • FIG. 6 is a schematic illustration of a pull roll apparatus according to a fifth exemplary embodiment
  • FIG. 7A to FIG. 7C are schematic illustrations of a sheet separating device according to an exemplary embodiment
  • FIG. 8A and FIG. 8B are, respectively, a schematic illustration and flowchart conceptually illustrating a method of assessing the difference in a wear amount between exemplary draw rolls according to some embodiments;
  • FIG. 9 is a flowchart conceptually illustrating a method of compensating for the difference in wear amounts that has been assessed by the method of FIG. 8B according to some embodiments;
  • FIG. 10 is a flowchart conceptually illustrating a method of assessing a difference between drawing conditions in which draw rolls draw a glass ribbon according to some embodiments;
  • FIG. 11 is a flowchart conceptually illustrating a method of decreasing the difference between the drawing conditions assessed by the method of FIG. 10 according to some embodiments;
  • FIG. 12 is a flowchart illustrating a specified example of the methods of FIG. 9 and FIG. 11;
  • FIG. 13A and FIG. 13B are charts illustrating differences between values of driving currents obtained for a relatively short period of time, before and after the method of FIG. 12 is implemented.
  • FIG. 14A and FIG. 14B are charts illustrating differences between values of drawing forces obtained for a relatively long period of time, before and after the method of FIG. 12 is implemented.
  • FIG. 1 to FIG. 6 illustrate a glass manufacturing apparatus 300 and pull roll apparatuses 440, 540, 640, 740, and 840 that are configured and operate according to several exemplary embodiments.
  • the pull roll apparatuses 440, 540, 640, 740, and 840 are described herein as being used in the glass manufacturing apparatus 300 using a downdraw fusion process, it should be understood that the pull roll apparatuses 440, 540, 640, 740, and 840 could be used for any other types of glass manufacturing apparatuses that draw a glass ribbon 305. Accordingly, the pull roll apparatuses 440, 540, 640, 740, and 840 of the present disclosure should not be construed in a limited manner.
  • FIG. 1 is a schematic illustration of an exemplary embodiment of a glass manufacturing apparatus 300 using one of the pull roll apparatuses 440, 540, 640, 740, and 840 to manufacture a glass ribbon.
  • the glass manufacturing apparatus 300 includes a melting vessel 310, a fining vessel 315, a mixing vessel 320, a delivery vessel 325, a forming vessel 335 (, a pull roll apparatus 440, 540, 640, 740, or 840 and a sheet separating device 900.
  • the melting vessel 310 is a place into which glass batch materials are introduced as shown by arrow 312 and are melted to form molten glass 326.
  • the fining vessel 315 has a high temperature processing area that receives the molten glass 326 from the melting vessel 310 and in which bubbles are removed from the molten glass 326.
  • the fining vessel 315 is connected to the mixing vessel 320 (by a fining vessel to mixing vessel connecting tube 322.
  • the mixing vessel 320 is connected to the delivery vessel 325 by a mixing vessel to delivery vessel connecting tube 327.
  • the delivery vessel 325 delivers the molten glass 326 into a forming device 335 through a downcomer 330.
  • the forming device 335 has an inlet 332 through which the molten glass 326 is introduced.
  • the molten glass 326 flows into a trough 337 and then overflows and runs down two sides 338a and 338b of the forming device 335 before fusing together at a root 339 thereof.
  • the root 339 is a place at which the two flows of the molten glass 326 rejoin (e.g., fuse) before being drawn downwards in a draw direction 306 by the pull roll apparatus 440, 540, 640, 740, and 840 to form the glass ribbon 305.
  • the sheet separating device 900 scores the drawn glass ribbon 305, which is then separated into individual glass sheets 355.
  • FIG. 2A to FIG. 2C are schematic illustrations associated with the pull roll apparatus 440 configured according to an exemplary embodiment.
  • the pull roll apparatus 440 includes a pull roll device and a control device 446 (e.g., a programmable logic controller 446).
  • the pull roll device includes a first draw roll pair 442 and a second draw roll pair 444.
  • the control device 446 controls the two draw roll pairs 442 and 444 while a first edge portion 305a of the glass ribbon 305 is drawn between two rolls 450a and 450b which are associated with the first draw roll pair 442 and while an opposing second edge portion 305b of the glass ribbon 305 is drawn between two rolls 452a and 452b which are associated with the second draw roll pair 444.
  • the draw roll pairs may be vertically downtilted to create a cross-draw tension (i.e., a tension in a direction orthogonal to the draw direction 306), as well as a down-draw tension in the glass ribbon 305 (i.e., a tension in the draw direction 306).
  • the two draw roll pairs 442 and 444 are not positioned to have an uptilt because this would cause undesirable compressive force across the glass ribbon 305 which would deform and stress the glass ribbon 305.
  • the rolls 450a, 450b, 452a, and 452b can also be positioned to have a predetermined splay angle which is a horizontal angle ⁇ by which a respective face of the downtilted rolls 450a, 450b, 452a, and 452b can be positioned relative to a respective major surface 305c and 305d of the glass ribbon 305 (see FIG. 2C) (note: the pull roll apparatus 740 discussed with respect to FIG. 5 has horizontally level rolls 450a, 450b, 452a, and 452b and these particular rolls, if desired, can also be positioned to have a predetermined splay angle).
  • a positive splay angle ⁇ generates a cross-draw tension 448a, which is preferred.
  • FIG. 2C illustrates the pull roll apparatus 440 with a positive splay angle ⁇ ).
  • the pull roll apparatus 440 includes driving devices 454a, 454b, 456a, and 456b for driving the respective rolls, e.g., servo motors which may or may not use a gear box.
  • FIG. 3 is a diagram associated with the pull roll apparatus 540 according to an exemplary embodiment.
  • the pull roll apparatus 540 includes an additional pulling roll assembly 500 in addition to the components associated with the first described pull roll apparatus 440, namely a first draw roll pair 442, a second draw roll pair 444, and a control device 446 (e.g., a programmable logic controller 446).
  • the draw roll pair 500 includes a first draw roll 502 (having two ends 502a and 502b optionally coated with a compressible refractory roll covering) and a second draw roll 504 (having two ends 504a and 504b optionally coated with a compressible refractory roll covering) which extend across the glass ribbon 305.
  • the addition of the draw roll assembly 500 may also provide the ability to control different sets of down-draw tensions 448b and 448c within the glass ribbon.
  • the draw roll pairs 442 and 444 can control the down-draw tension 448b in the ribbon located between themselves and the forming device 335
  • the draw roll assembly 500 can control the down-draw tension 448c in the ribbon located between themselves and the draw roll pairs 442 and 444.
  • the pull roll apparatus 540 includes the driving devices 454a, 454b, 456a, 456b, 506, and 508 for driving the respective rolls.
  • FIG. 4 is a schematic illustration associated with the pull roll apparatus 640 according to an exemplary embodiment.
  • the pull roll apparatus 640 includes third and fourth draw roll pairs 602 and 604 in addition to the components associated with the first described pull roll apparatus 440, namely a first draw roll pair 442, a second draw roll pair 444 and a control device 446 (e.g., a programmable logic controller 446).
  • the third draw roll pair 602 is located directly below the first draw roll pair 442, and has two rolls 606a and 606b between which the first edge portion 305a of the glass ribbon 305 is drawn.
  • the fourth draw roll pair 604 is located directly below the second draw roll pair 444, and has two rolls 608a and 608b between which the opposing second edge portion 305b of the glass ribbon 305 is drawn.
  • the third and fourth draw roll pairs may be vertically downtilted, although in further embodiments the third and fourth draw roll pairs may be horizontally positioned.
  • draw roll pairs 602 and 604 provide the ability to control different sets of the cross draw tensions 448a and 448d and the down-draw sheet tensions 448b and 448c within the ribbon.
  • the upper draw roll pairs 442 and 444 can control the cross-draw tension 448a and the down-draw tension 448b in the ribbon located between themselves and the forming device 335
  • the lower draw roll pairs 602 and 604 can control the cross-draw tension 448d and the down-draw tension 448c in the ribbon located between themselves and the upper draw roll pairs 442 and 444.
  • the pull roll apparatus 640 includes the driving devices 454a, 454b, 456a, 456b, 610a, 610b, 612a, and 612b for driving the respective rolls.
  • FIG. 5 is a schematic illustration associated with the pull roll apparatus 740 according to an exemplary embodiment.
  • the pull roll apparatus 740 includes a first draw roll pair 442, a second draw roll pair 444, and a control device 446 (e.g., a computer 446 or a programmable logic controller 446).
  • a control device 446 e.g., a computer 446 or a programmable logic controller 446.
  • the control device 446 effectively controls a down-draw tension 448b in the glass ribbon 305 by controlling the two draw roll pairs 442 and 444 while a first edge portion 305a of the glass ribbon 305 is drawn between two horizontal rolls 450a and 450b which are associated with the first draw roll pair 442 and while an opposing second edge portion 305b of the glass ribbon 305 is drawn between two horizontal rolls 452a and 452b which are associated with the second draw roll pair 444.
  • the horizontal rolls 450a, 450b, 452a, and 452b can also be positioned (either automatically, for example by control device 446, or manually) to have a predetermined positive splay angle which controls the amount of cross-draw force 448a generated across the glass ribbon 305.
  • the pull roll apparatus 740 may also incorporate the pulling roll assembly 500 (see FIG. 3) or the third and fourth draw roll pairs 602 and 604 (see FIG. 4).
  • FIG. 6 is a schematic illustration associated with the pull roll apparatus 840 according to an exemplary embodiment.
  • the pull roll apparatus 840 includes a first draw roll 842 (having two ends 842a and 842b coated with a compressible refractory roll covering) and a second draw roll 844 (having two ends 844a and 844b coated with a compressible refractory roll covering) which extend across the glass ribbon 305 and draw the edges 305a and 305b of the glass ribbon 305.
  • the pull roll apparatus 840 further includes a driving device 846 operatively connected to the first draw roll 842 and a driving device 846 operatively connected to the second draw roll 844.
  • the pull roll apparatus 840 may also incorporate at least one of the draw roll pairs in FIGs. 2A to 5.
  • FIG. 7A to FIG. 7C illustrate a sheet separating device 900 according to an exemplary embodiment.
  • FIG. 7A illustrates the overall configuration of the sheet separating device 900 at a point at which the leading edge of a glass ribbon 305 is passing through a scoring sub-assembly 921 to enter the area of a sheet removal sub-assembly 915.
  • the scoring sub-assembly 921 includes an anvil 923, a scribe 925, and a scribe transporter 927.
  • the scoring sub-assembly may be of a moving scribe/moving anvil type as is known in the related art, although other types of scoring systems may be used if desired, e.g., laser based systems.
  • the sheet removal sub-assembly 915 includes a frame 917, for example a rectangular frame, which carries sheet engaging members 919, e.g., four pane engaging members, deployed at the four corners of the frame, whose dimensions are smaller than the width and length of sheet 355.
  • the sheet engaging members 919 may, for example, be soft vacuum suction cups, although other apparatus for engaging a sheet of glass, e.g., clamps, may be used if desired.
  • the sheet removal sub-assembly 915 includes a transporter 929 which is connected to the frame 917 through a connector assembly 931.
  • the transporter 929 may be an industrial robot and/or a fixed automation device for providing linear and rotational motion to the frame and the connector assembly.
  • the connector assembly 931 allows the frame 917 and a glass sheet attached to the frame 917 to undergo a controlled “fall” relative to the transporter, once separation of the sheet 355 from the ribbon 305 has occurred at a separation line 947 that extends at least across a portion of the width of the glass ribbon 305 in a direction orthogonal to the draw direction 306.
  • FIG. 7B illustrates the formation of the separation line 947 in the glass ribbon 305 by the scribe 925.
  • the sheet engaging members 919 have engaged the glass sheet. This engagement may take place either before or after the sheet is scored. The engagement may be achieved using a rigid arrangement of the sheet engaging members with respect to the sheet in combination with the use of sufficiently soft engaging members, e.g., soft vacuum suction cups, which will not cause undue motion of the sheet.
  • the removal sub-assembly 915 should be attached to the sheet before a bending moment, which separates the sheet 355 from the ribbon 305, is applied.
  • FIG. 7C illustrates the application of the bending moment.
  • the bending moment may be applied in a direction toward the first side (unscored side) of the sheet using the anvil 923 as a stop about which rotation takes place.
  • sheet engaging members 919 may engage with the un-scored side of the glass ribbon 305 below the score line and, through transporter 929, the portion of the glass ribbon 305 below the score line is rotate in a direction that opens the score line.
  • the tension stress thereby applied across the score line causes the crack associated with the score line to extend through the thickness of the glass ribbon, thereby separating a glass sheet from the glass ribbon.
  • the connector assembly 931 immediately moves the trailing edge of the separated glass sheet away from the leading edge of the continually moving glass ribbon 305. In this way, edge damage to the glass sheet, the glass ribbon or both the glass sheet and the glass ribbon can be minimized.
  • the glass manufacturing apparatus 300 includes at least one draw roll pair and at least one driving device pair.
  • the draw roll pair may be one selected from among the draw roll pairs 442, 444, 500, 602, 604, and 842/844 illustrated in FIG. 2A to FIG. 6.
  • the driving device pair may be one selected from among the pairs of driving devices 454a/454b, 456a/456b, 506/508, 610a/610b, 612a/612b, and 846/848 illustrated in FIG. 2A to FIG. 6.
  • the following description will be given in relation to the draw roll pair 442 and the pair of driving devices 454a and 454b for the sake of brevity.
  • FIG. 8A and FIG. 8B are, respectively, a schematic illustration and flowchart conceptually illustrating a method of assessing the difference in wear between draw rolls according to some embodiments.
  • the control device 446 controls electrical driving currents supplied to the first driving device 454a and the second driving device 454b such that the first draw roll 450a and the second draw roll 450b rotate at respective predetermined angular speeds.
  • the control device 446 may form a feedback system to adjust the electrical driving currents such that the draw rolls 450a, 450b can rotate at the same angular speed.
  • the draw rolls 450a, 450b become worn.
  • the draw rolls 450a, 450b may have been worn in different amounts, as illustrated in FIG. 8A, which causes linear speeds at which the circumferential surfaces move to be different, even when the draw rolls 450a, 450b have the same angular speed.
  • This consequently causes a draw roll with a lower linear speed, that is, a more worn draw roll, to slip on the glass ribbon, causing adverse effects on the forming quality, and accelerating the wear of the more worn draw roll with the lower linear speed.
  • FIG. 8B conceptually illustrates the method of assessing the amount of wear.
  • the control device 446 monitors a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll. Afterwards, the control device 446 may assess a first wear amount by which the first draw roll has been worn and a second wear amount by which the second draw roll has been worn based on a comparison between the first electrical driving current and the second electrical driving current. Specifically, one of the draw rolls driven by a lower electrical driving current may be assessed to have been worn more than the other draw roll driven by a higher electrical driving current.
  • the draw roll that has been worn more may be determined based on a comparison between the electrical driving currents.
  • FIG. 9 is a flowchart conceptually illustrating a method of compensating for the difference in wear amounts that has been assessed by the method of FIG. 8B.
  • the pull roll device is operated such that the first draw roll 450a rotates in a first rotating condition to draw one surface of the glass ribbon 305 and the second draw roll 450b rotates in a second rotating condition to draw the other surface of the glass ribbon 305.
  • the control device 446 assesses whether or not a first wear amount by which the first draw roll 450a has been worn is substantially different from a second wear amount by which the second draw roll 450b has been worn by comparing the electrical driving current supplied to the first driving device 454a and the electrical driving current supplied to the second driving device 454b. Afterwards, when the first wear amount is assessed to be substantially different from the second wear amount, the control device 446 modifies at least one of the first and second rotating conditions to compensate for the difference between the first wear amount and the second wear amount.
  • the first and second rotating conditions may be first and second predetermined angular speeds of the first and second draw rolls 450a, 450b.
  • the control device 446 monitors the first electrical driving current supplied to the first driving device 454a to drive the first draw roll 450a and the second electrical driving current supplied to the second driving device 454b to drive the second draw roll 450b. Afterwards, when the difference between the first driving current and the second driving current exceeds a predetermined range, the first wear amount and the second wear amount may be assessed to be substantially different from each other. In this case, the control device 446 may increase the angular speed of the draw roll driven by a lower electrical driving current to be greater than the immediately preceding predetermined angular speed.
  • the control device 446 decreases a predetermined diameter of one of the first and second draw rolls 450a, 450b driven by a lower driving current to be smaller than the immediately preceding predetermined diameter thereof.
  • the predetermined diameter indicates a diameter which the control device 446 recognizes as a current diameter of the first or second draw roll 450a, 450b. Most of the time, the values of the predetermined diameters will be different from the values of the actual diameters thereof.
  • the values of the predetermined diameters thereof will be greater than the values of the actual diameters thereof.
  • the values of the predetermined diameters may be initially input manually by an operator and updated manually by an operator or automatically as a result of a difference between the first and second electrical driving currents. Afterwards, in response to the decrease of the diameter of the draw roll driven by the lower driving current, the control device 446 may increase the predetermined angular speed of the draw roll driven by the lower electrical driving current as a function of the predetermined diameter thereof.
  • the linear speed of the draw roll i.e., the speed at which the draw roll draws the glass ribbon
  • the increase of the angular speed of the draw roll causes the linear speed of the draw roll that has been worn more to increase.
  • FIG. 10 is a flowchart conceptually illustrating a method of assessing a difference between drawing conditions in which the draw rolls 450a, 450b draw the glass ribbon 305 according to some embodiments.
  • the pull roll device is operated such that the first draw roll 450a rotates to draw one surface of the glass ribbon 305 in a first drawing condition and the second draw roll 450b rotates to draw the other surface of the glass ribbon 305 in a second drawing condition.
  • the control device 446 monitors a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll. Afterwards, the control device 446 may assess the first drawing condition and the second drawing condition based on the first current and the second current.
  • control device 446 may assess the first drawing condition and the second drawing condition to be substantially different from each other.
  • Each of the first and second drawing conditions may include i) a drawing force with which the corresponding draw roll of the first and second draw rolls 450a, 450b draws the glass ribbon 305 and ii) a drawing speed at which the corresponding draw roll of the first and second draw rolls 450a, 450b draws the glass ribbon 305.
  • control device 446 may assess the drawing force with which one of the first and second draw rolls 450a, 450b driven by a lower electrical driving current draws the glass ribbon 305 to be less than the drawing force with which the other draw roll draws the glass sheet 305.
  • control device 446 may assesses the drawing speed at which the one of the first and second draw rolls 450a, 450b driven by the lower driving current draws the glass ribbon 305 to be less than the drawing speed at which the other draw roll draws the glass ribbon 305.
  • FIG. 11 is a flowchart conceptually illustrating a method of decreasing the difference between the drawing conditions assessed by the method of FIG. 10 according to some embodiments.
  • the pull roll device is operated such that the first draw roll 450a rotates in a first rotating condition to draw one surface of the glass ribbon 305 in a first drawing condition and the second draw roll 450b rotates in a second rotating condition to draw the other surface of the glass ribbon 305 in a second drawing condition.
  • the control device 446 assesses whether or not the first drawing condition and the second drawing condition are substantially different from each other. Afterwards, when the first drawing condition and the second drawing condition are assessed to be substantially different from each other, the control device 446 may modify one of the first drawing condition and the second drawing condition to decrease the difference between the first drawing condition and the second drawing condition.
  • control device 446 may increase the angular speed of one of the first and second draw rolls driven by a lower driving current to be greater than the immediately preceding predetermined angular speed.
  • control device 446 may decrease the diameter of the one of the first and second draw rolls driven by the lower driving current to be smaller than the immediately preceding predetermined diameter. Afterwards, in response to the decrease of the diameter, the control device 446 may increase the predetermined angular speed of the draw roll driven by the lower driving current as a function of the predetermined diameter thereof.
  • FIG. 12 is a flowchart illustrating a specified example of the methods of FIG. 9 and FIG. 11.
  • no values of electrical driving current obtained and/or obtainable during a separating period when the sheet separating device 900 is in contact with the glass ribbon 305 are used in the assessment of wear amount and the assessment of drawing conditions.
  • the control device 446 may monitor the driving currents during a preparation period when the sheet separating device 900 is not in contact with the glass ribbon 305, and then, perform the assessment using only the electrical driving currents obtained during the preparation period.
  • values of driving currents supplied to the driving devices may be obtained as follows: i) the control device 446 may monitor a first series of electrical driving currents and a second series of electrical driving currents supplied to the first driving 454a device and the second driving device 454b, respectively, at regular intervals in every period in which a single glass sheet is produced.
  • the control device 446 may calculate the moving averages thereof, and then use the obtained average electrical driving current values in the assessment of wear amount and the assessment of drawing conditions.
  • the control device 446 may calculate a difference in electrical driving current values, i.e. the difference between a first electrical driving current (the average of the first series of electrical driving currents in the embodiments as described above) supplied to the first driving device 454a and a second electrical driving current (the average of the second series of electrical driving currents in the embodiments as described above) supplied to the second driving device 454b, and then, compare the first and second electrical driving currents with each other to determine whether or not the difference in driving current values exceeds a predetermined difference range.
  • the control device 446 may assess one of the two draw rolls 450a, 450b driven by a lower driving voltage to have been worn more than the other draw roll.
  • the control device 446 may wait for the next point in time of comparison.
  • the difference in electrical driving current values is greater than the predetermined difference range, the predetermined diameter of the draw roll driven by a higher electrical driving current remains unchanged, while the control device 446 may identify the draw roll driven by a lower electrical driving current as a more worn draw roll and decrease the predetermined diameter thereof by a predetermined amount (e.g. 0.0005”).
  • the glass manufacturing apparatus 300 may be configured to sequentially repeat the assessment operation by which the drawing conditions, the wear amounts, and/or the driving currents are assessed and the modification operation by which at least one of the first and second rotating conditions is modified, as described above.
  • the control device 446 may terminate the repetition without proceeding to the modification operation when a difference between the first electrical driving current and the second electrical driving current is determined to continue to increase while the modification operation by which the at least one of the first and second rotating conditions is modified is repeated a predetermined number of times.
  • the control device 446 when the predetermined diameter has been modified by the immediately preceding modification operation, the control device 446 observes a change in the difference in electrical driving current values. When the new difference is smaller than or equal to the immediately preceding difference, the control device 446 initializes the count number as zero (0). In contrast, when the new difference is greater than the immediately preceding difference, the control device 446 increases the count number by 1. When the count number reaches a predetermined value (e.g., 5), the difference in electrical driving current values is interpreted as gradually increasing. In this case, the control device 446 may terminate the control process for compensating for wear and decreasing differences in drawing conditions.
  • a predetermined value e.g., 5
  • FIG. 13A and FIG. 13B are charts illustrating differences between values of electrical driving currents obtained for a relatively short period of time, before and after the method of FIG. 12 is implemented.
  • the values of a first electrical driving current DC1 (maximum 0.075 and minimum -0.15) were significantly smaller than the values of a second electrical driving current DC2 (maximum 0.275 and minimum 0.075).
  • the values of the first electrical driving current DC1 (maximum 0.15 and minimum -0.08) became substantially the same as the values of the second electrical driving current DC2 (maximum 0.275 and minimum 0.075).
  • FIG. 14A and FIG. 14B are charts illustrating differences between values of drawing forces obtained for a relatively long period of time, before and after the method of FIG. 12 is implemented.
  • a first drawing force DF1 was significantly less than a second drawing force DF2.
  • the first drawing force DF1 became substantially the same as the second drawing force DF2.
  • the present disclosure it is possible to compensate for the difference in the amount of wear between the draw rolls in real time by repeatedly monitoring changes in the electrical driving currents supplied to the driving devices during a period in which a single glass sheet is produced. It is thereby possible to ensure reducing a difference in operation parameters due to different amounts of wear of the draw rolls, even if the actual diameter of the first draw roll is substantially different from the diameter of the second draw roll.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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  • Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)

Abstract

A glass manufacturing apparatus and a method are provided. The method includes the steps of: a) forming a glass ribbon having a width; c) operating a pull roll device, comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device driving the first draw roll and a second driving device driving the second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon; b) determining whether a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and c) modifying at least one of the first and second rotating conditions when the first and second driving currents are determined to be substantially different from each other.

Description

GLASS MANUFACTURING APPARATUS AND METHOD
This application claims the benefit of priority under 35 U.S.C. § 119 of Korean Patent Application Serial No. 2016/0063049 filed on May 23, 2016, the content of which is relied upon and incorporated herein by reference in its entirety.
The present disclosure generally relates to a glass manufacturing apparatus and method. More particularly, the present disclosure relates to a glass manufacturing apparatus and a method for manufacturing a glass sheet by drawing a glass ribbon using at least one pair of draw rolls.
A fusion process (e.g. an overflow downdraw process) is known as a method of forming thin, high-quality glass sheets that can be used in a variety of devices, such as flat panel displays. The fusion process is a preferred technique for producing glass sheets used in flat panel displays because glass sheets produced thereby have superior surface flatness and smoothness when compared to glass sheets produced using other methods.
Several glass manufacturing apparatuses, including a glass manufacturing apparatus using the fusion process as described above, form a glass ribbon by drawing it between a pair of draw rolls. When such draw rolls are used for a prolonged period of time, a difference between drawing conditions and/or amounts of wear of the matching two draw rolls may occur. This difference may have an adverse effect on product quality. Therefore, a new solution for overcoming this problem is desired.
Various aspects of the present disclosure are intended to reduce a difference in draw conditions of matching draw rolls and/or to compensate for a difference in amounts of wear of the matching draw rolls, thereby manufacturing a glass ribbon having superior quality.
According to an aspect, a method of manufacturing a glass ribbon may include:
a) forming a glass ribbon having a width;
b) operating a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
c) assessing whether the first and second drawing conditions are substantially different from each other; and
d) modifying at least one of the first and second rotating conditions to decrease a difference between the first and second drawing conditions when the first and second drawing conditions are assessed to be substantially different from each other.
According to another aspect, a method of manufacturing a glass ribbon may include:
a) forming a glass ribbon having a width;
b) operating a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
c) assessing whether a first wear amount of the first draw roll by which the first draw roll has worn away is substantially different from a second wear amount of the second draw roll by which the second draw roll has worn away, and
d) modifying at least one of the first and second rotating conditions to compensate for a difference between the first wear amount and the second wear amount when the first wear amount and the second wear amount are assessed to be substantially different from each other.
According to still another aspect, a method of assessing drawing conditions may include:
a) operating a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet in a first drawing condition and the second draw roll rotates to draw the other surface of the sheet in a second drawing condition;
b) monitoring a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll; and
c) assessing the first and second drawing conditions based on the first and second driving currents.
According to still another aspect, a method of assessing amounts of wear of draw rolls may include:
a) operating a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet and the second draw roll rotates to draw the other surface of the sheet;
b) monitoring a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll; and
c) assessing a first wear amount of the first draw roll by which the first draw roll has worn away and a second wear amount of the second draw roll by which the second draw roll has worn away, based on the first and second driving currents.
According to still another aspect, a method of manufacturing a glass ribbon may include:
b) forming a glass ribbon having a width;
c) operating a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device driving the first draw roll and a second driving device driving the second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
d) determining whether a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
e) modifying at least one of the first and second rotating conditions when the first and second driving currents are determined to be substantially different from each other.
According to still another aspect, a glass manufacturing apparatus may include:
a forming device configured to form a glass ribbon having a width;
a pull roll device configured to draw the glass ribbon along a draw path extending transverse to the width from the forming device, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll; and
a control device configured to:
operate the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
determine whether a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
modify at least one of the first and second rotating conditions when the first driving current and the second driving current are determined to be substantially different from each other.
According to still another aspect, a pull roll apparatus may include:
a pull roll device configured to draw a glass ribbon having a width along a draw path extending transverse to the width, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll; and
a control device configured to:
operate the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
determine whether a first driving current supplied to the first driving device to drive the first draw roll and a second driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
modify at least one of the first and second rotating conditions when the first driving current and the second driving current are determined to be substantially different from each other.
The above and other objects, features and advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic illustration of a glass manufacturing apparatus used to manufacture a glass sheet according to an exemplary embodiment;
FIG. 2A to FIG. 2C are schematic illustrations of a pull roll apparatus according to a first exemplary embodiment;
FIG. 3 is schematic illustration of a pull roll apparatus according to a second exemplary embodiment;
FIG. 4 is a schematic illustration of a pull roll apparatus according to a third exemplary embodiment;
FIG. 5 is a schematic illustration of a pull roll apparatus according to a fourth exemplary embodiment;
FIG. 6 is a schematic illustration of a pull roll apparatus according to a fifth exemplary embodiment;
FIG. 7A to FIG. 7C are schematic illustrations of a sheet separating device according to an exemplary embodiment;
FIG. 8A and FIG. 8B are, respectively, a schematic illustration and flowchart conceptually illustrating a method of assessing the difference in a wear amount between exemplary draw rolls according to some embodiments;
FIG. 9 is a flowchart conceptually illustrating a method of compensating for the difference in wear amounts that has been assessed by the method of FIG. 8B according to some embodiments;
FIG. 10 is a flowchart conceptually illustrating a method of assessing a difference between drawing conditions in which draw rolls draw a glass ribbon according to some embodiments;
FIG. 11 is a flowchart conceptually illustrating a method of decreasing the difference between the drawing conditions assessed by the method of FIG. 10 according to some embodiments;
FIG. 12 is a flowchart illustrating a specified example of the methods of FIG. 9 and FIG. 11;
FIG. 13A and FIG. 13B are charts illustrating differences between values of driving currents obtained for a relatively short period of time, before and after the method of FIG. 12 is implemented; and
FIG. 14A and FIG. 14B are charts illustrating differences between values of drawing forces obtained for a relatively long period of time, before and after the method of FIG. 12 is implemented.
Hereinafter, embodiments of the present disclosure will be described as follows with reference to the attached drawings, so that a person having ordinary skill in the art to which the present disclosure relates could easily put the present disclosure into practice.
Descriptions of specific exemplary embodiments of the present disclosure have been presented with respect to the drawings. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed herein, and many different modifications and variations are obviously possible for a person having ordinary skill in the art in light of the above teachings.
It is intended therefore that the scope of the present disclosure not be limited to the foregoing embodiments, but be defined by the Claims appended hereto and their equivalents.
Throughout this document, reference should be made to the drawings, in which, unless otherwise indicated, the same reference numerals and symbols will be used throughout the different drawings to designate the same or like components. In the following description, detailed descriptions of known functions and components incorporated herein will be omitted in the case that the subject matter of the present disclosure is rendered unclear by the inclusion thereof.
FIG. 1 to FIG. 6 illustrate a glass manufacturing apparatus 300 and pull roll apparatuses 440, 540, 640, 740, and 840 that are configured and operate according to several exemplary embodiments. Although the pull roll apparatuses 440, 540, 640, 740, and 840 are described herein as being used in the glass manufacturing apparatus 300 using a downdraw fusion process, it should be understood that the pull roll apparatuses 440, 540, 640, 740, and 840 could be used for any other types of glass manufacturing apparatuses that draw a glass ribbon 305. Accordingly, the pull roll apparatuses 440, 540, 640, 740, and 840 of the present disclosure should not be construed in a limited manner.
FIG. 1 is a schematic illustration of an exemplary embodiment of a glass manufacturing apparatus 300 using one of the pull roll apparatuses 440, 540, 640, 740, and 840 to manufacture a glass ribbon. The glass manufacturing apparatus 300 includes a melting vessel 310, a fining vessel 315, a mixing vessel 320, a delivery vessel 325, a forming vessel 335 (, a pull roll apparatus 440, 540, 640, 740, or 840 and a sheet separating device 900.
The melting vessel 310 is a place into which glass batch materials are introduced as shown by arrow 312 and are melted to form molten glass 326. The fining vessel 315 has a high temperature processing area that receives the molten glass 326 from the melting vessel 310 and in which bubbles are removed from the molten glass 326. The fining vessel 315 is connected to the mixing vessel 320 (by a fining vessel to mixing vessel connecting tube 322. In addition, the mixing vessel 320 is connected to the delivery vessel 325 by a mixing vessel to delivery vessel connecting tube 327. The delivery vessel 325 delivers the molten glass 326 into a forming device 335 through a downcomer 330. The forming device 335 has an inlet 332 through which the molten glass 326 is introduced. The molten glass 326 flows into a trough 337 and then overflows and runs down two sides 338a and 338b of the forming device 335 before fusing together at a root 339 thereof. The root 339 is a place at which the two flows of the molten glass 326 rejoin (e.g., fuse) before being drawn downwards in a draw direction 306 by the pull roll apparatus 440, 540, 640, 740, and 840 to form the glass ribbon 305. Then, the sheet separating device 900 scores the drawn glass ribbon 305, which is then separated into individual glass sheets 355.
Referring to FIG. 2 to FIG. 6, the pull roll apparatuses 440, 540, 640, 740, and 840 will now be described in detail.
FIG. 2A to FIG. 2C are schematic illustrations associated with the pull roll apparatus 440 configured according to an exemplary embodiment. As illustrated in FIG. 2A, the pull roll apparatus 440 includes a pull roll device and a control device 446 (e.g., a programmable logic controller 446). The pull roll device includes a first draw roll pair 442 and a second draw roll pair 444. The control device 446 controls the two draw roll pairs 442 and 444 while a first edge portion 305a of the glass ribbon 305 is drawn between two rolls 450a and 450b which are associated with the first draw roll pair 442 and while an opposing second edge portion 305b of the glass ribbon 305 is drawn between two rolls 452a and 452b which are associated with the second draw roll pair 444. In some embodiments, the draw roll pairs may be vertically downtilted to create a cross-draw tension (i.e., a tension in a direction orthogonal to the draw direction 306), as well as a down-draw tension in the glass ribbon 305 (i.e., a tension in the draw direction 306). In these examples, the two draw roll pairs 442 and 444 are not positioned to have an uptilt because this would cause undesirable compressive force across the glass ribbon 305 which would deform and stress the glass ribbon 305. In addition, it may be desirable to downtilt the rolls 450a and 450b differently on one side than the rolls 452a and 452b on the other side, depending on the processing conditions (note: the pull roll apparatus 740 discussed with respect to FIG. 5 does not have vertically downtilted rolls 450a, 450b, 452a and 452b but instead has horizontally level rolls 450a, 450b, 452a and 452b).
If desired, the rolls 450a, 450b, 452a, and 452b can also be positioned to have a predetermined splay angle which is a horizontal angle θ by which a respective face of the downtilted rolls 450a, 450b, 452a, and 452b can be positioned relative to a respective major surface 305c and 305d of the glass ribbon 305 (see FIG. 2C) (note: the pull roll apparatus 740 discussed with respect to FIG. 5 has horizontally level rolls 450a, 450b, 452a, and 452b and these particular rolls, if desired, can also be positioned to have a predetermined splay angle). A positive splay angle θ generates a cross-draw tension 448a, which is preferred. In contrast, a negative splay angle θ generates compressive force across the glass ribbon 305 which is not preferred since such a force would deform and stress the glass ribbon 305 (note: FIG. 2C illustrates the pull roll apparatus 440 with a positive splay angle θ).
The pull roll apparatus 440 includes driving devices 454a, 454b, 456a, and 456b for driving the respective rolls, e.g., servo motors which may or may not use a gear box.
FIG. 3 is a diagram associated with the pull roll apparatus 540 according to an exemplary embodiment. As illustrated in FIG. 3, the pull roll apparatus 540 includes an additional pulling roll assembly 500 in addition to the components associated with the first described pull roll apparatus 440, namely a first draw roll pair 442, a second draw roll pair 444, and a control device 446 (e.g., a programmable logic controller 446). The draw roll pair 500 includes a first draw roll 502 (having two ends 502a and 502b optionally coated with a compressible refractory roll covering) and a second draw roll 504 (having two ends 504a and 504b optionally coated with a compressible refractory roll covering) which extend across the glass ribbon 305.
The addition of the draw roll assembly 500 may also provide the ability to control different sets of down- draw tensions 448b and 448c within the glass ribbon. For instance, the draw roll pairs 442 and 444 can control the down-draw tension 448b in the ribbon located between themselves and the forming device 335, and the draw roll assembly 500 can control the down-draw tension 448c in the ribbon located between themselves and the draw roll pairs 442 and 444.
The pull roll apparatus 540 includes the driving devices 454a, 454b, 456a, 456b, 506, and 508 for driving the respective rolls.
FIG. 4 is a schematic illustration associated with the pull roll apparatus 640 according to an exemplary embodiment. As illustrated in FIG. 4, the pull roll apparatus 640 includes third and fourth draw roll pairs 602 and 604 in addition to the components associated with the first described pull roll apparatus 440, namely a first draw roll pair 442, a second draw roll pair 444 and a control device 446 (e.g., a programmable logic controller 446). According to the present embodiment, the third draw roll pair 602 is located directly below the first draw roll pair 442, and has two rolls 606a and 606b between which the first edge portion 305a of the glass ribbon 305 is drawn. Likewise, the fourth draw roll pair 604 is located directly below the second draw roll pair 444, and has two rolls 608a and 608b between which the opposing second edge portion 305b of the glass ribbon 305 is drawn. In some embodiments, the third and fourth draw roll pairs may be vertically downtilted, although in further embodiments the third and fourth draw roll pairs may be horizontally positioned.
The addition of the draw roll pairs 602 and 604 provide the ability to control different sets of the cross draw tensions 448a and 448d and the down- draw sheet tensions 448b and 448c within the ribbon. For instance, the upper draw roll pairs 442 and 444 can control the cross-draw tension 448a and the down-draw tension 448b in the ribbon located between themselves and the forming device 335, and the lower draw roll pairs 602 and 604 can control the cross-draw tension 448d and the down-draw tension 448c in the ribbon located between themselves and the upper draw roll pairs 442 and 444.
The pull roll apparatus 640 includes the driving devices 454a, 454b, 456a, 456b, 610a, 610b, 612a, and 612b for driving the respective rolls.
FIG. 5 is a schematic illustration associated with the pull roll apparatus 740 according to an exemplary embodiment. As illustrated in FIG. 5, the pull roll apparatus 740 includes a first draw roll pair 442, a second draw roll pair 444, and a control device 446 (e.g., a computer 446 or a programmable logic controller 446). The control device 446 effectively controls a down-draw tension 448b in the glass ribbon 305 by controlling the two draw roll pairs 442 and 444 while a first edge portion 305a of the glass ribbon 305 is drawn between two horizontal rolls 450a and 450b which are associated with the first draw roll pair 442 and while an opposing second edge portion 305b of the glass ribbon 305 is drawn between two horizontal rolls 452a and 452b which are associated with the second draw roll pair 444.
If desired, the horizontal rolls 450a, 450b, 452a, and 452b can also be positioned (either automatically, for example by control device 446, or manually) to have a predetermined positive splay angle which controls the amount of cross-draw force 448a generated across the glass ribbon 305. In addition, the pull roll apparatus 740 may also incorporate the pulling roll assembly 500 (see FIG. 3) or the third and fourth draw roll pairs 602 and 604 (see FIG. 4).
FIG. 6 is a schematic illustration associated with the pull roll apparatus 840 according to an exemplary embodiment.
As illustrated in FIG. 6, the pull roll apparatus 840 includes a first draw roll 842 (having two ends 842a and 842b coated with a compressible refractory roll covering) and a second draw roll 844 (having two ends 844a and 844b coated with a compressible refractory roll covering) which extend across the glass ribbon 305 and draw the edges 305a and 305b of the glass ribbon 305. The pull roll apparatus 840 further includes a driving device 846 operatively connected to the first draw roll 842 and a driving device 846 operatively connected to the second draw roll 844. In addition, the pull roll apparatus 840 may also incorporate at least one of the draw roll pairs in FIGs. 2A to 5.
FIG. 7A to FIG. 7C illustrate a sheet separating device 900 according to an exemplary embodiment.
FIG. 7A illustrates the overall configuration of the sheet separating device 900 at a point at which the leading edge of a glass ribbon 305 is passing through a scoring sub-assembly 921 to enter the area of a sheet removal sub-assembly 915. The scoring sub-assembly 921 includes an anvil 923, a scribe 925, and a scribe transporter 927. The scoring sub-assembly may be of a moving scribe/moving anvil type as is known in the related art, although other types of scoring systems may be used if desired, e.g., laser based systems.
The sheet removal sub-assembly 915 includes a frame 917, for example a rectangular frame, which carries sheet engaging members 919, e.g., four pane engaging members, deployed at the four corners of the frame, whose dimensions are smaller than the width and length of sheet 355. The sheet engaging members 919 may, for example, be soft vacuum suction cups, although other apparatus for engaging a sheet of glass, e.g., clamps, may be used if desired.
The sheet removal sub-assembly 915 includes a transporter 929 which is connected to the frame 917 through a connector assembly 931. The transporter 929 may be an industrial robot and/or a fixed automation device for providing linear and rotational motion to the frame and the connector assembly. The connector assembly 931 allows the frame 917 and a glass sheet attached to the frame 917 to undergo a controlled “fall” relative to the transporter, once separation of the sheet 355 from the ribbon 305 has occurred at a separation line 947 that extends at least across a portion of the width of the glass ribbon 305 in a direction orthogonal to the draw direction 306.
FIG. 7B illustrates the formation of the separation line 947 in the glass ribbon 305 by the scribe 925. As also illustrated in this figure, the sheet engaging members 919 have engaged the glass sheet. This engagement may take place either before or after the sheet is scored. The engagement may be achieved using a rigid arrangement of the sheet engaging members with respect to the sheet in combination with the use of sufficiently soft engaging members, e.g., soft vacuum suction cups, which will not cause undue motion of the sheet.
Whether the sheet removal sub-assembly 915 is engaged with the sheet before or after scoring, the removal sub-assembly 915 should be attached to the sheet before a bending moment, which separates the sheet 355 from the ribbon 305, is applied.
FIG. 7C illustrates the application of the bending moment. As illustrated in the figure, the bending moment may be applied in a direction toward the first side (unscored side) of the sheet using the anvil 923 as a stop about which rotation takes place. For example, sheet engaging members 919 may engage with the un-scored side of the glass ribbon 305 below the score line and, through transporter 929, the portion of the glass ribbon 305 below the score line is rotate in a direction that opens the score line. The tension stress thereby applied across the score line causes the crack associated with the score line to extend through the thickness of the glass ribbon, thereby separating a glass sheet from the glass ribbon. In some embodiments, the connector assembly 931 immediately moves the trailing edge of the separated glass sheet away from the leading edge of the continually moving glass ribbon 305. In this way, edge damage to the glass sheet, the glass ribbon or both the glass sheet and the glass ribbon can be minimized.
The glass manufacturing apparatus 300 according to the exemplary embodiments described herein includes at least one draw roll pair and at least one driving device pair. The draw roll pair may be one selected from among the draw roll pairs 442, 444, 500, 602, 604, and 842/844 illustrated in FIG. 2A to FIG. 6. The driving device pair may be one selected from among the pairs of driving devices 454a/454b, 456a/456b, 506/508, 610a/610b, 612a/612b, and 846/848 illustrated in FIG. 2A to FIG. 6. The following description will be given in relation to the draw roll pair 442 and the pair of driving devices 454a and 454b for the sake of brevity. However, it will be apparent to a person having ordinary skill in the art that the principle of the present disclosure that will be described hereinafter can be applied to the other draw roll pairs 444, 500, 602, 604, and 842/844 and the other pairs of driving devices 456a/456b, 506/508, 610a/610b, 612a/612b, and/or 846/848.
FIG. 8A and FIG. 8B are, respectively, a schematic illustration and flowchart conceptually illustrating a method of assessing the difference in wear between draw rolls according to some embodiments.
The control device 446 controls electrical driving currents supplied to the first driving device 454a and the second driving device 454b such that the first draw roll 450a and the second draw roll 450b rotate at respective predetermined angular speeds. For example, at the initial use of the first and second draw rolls, the control device 446 may form a feedback system to adjust the electrical driving currents such that the draw rolls 450a, 450b can rotate at the same angular speed.
As the use of the draw rolls 450a, 450b continues, the draw rolls 450a, 450b become worn. Here, the draw rolls 450a, 450b may have been worn in different amounts, as illustrated in FIG. 8A, which causes linear speeds at which the circumferential surfaces move to be different, even when the draw rolls 450a, 450b have the same angular speed. This consequently causes a draw roll with a lower linear speed, that is, a more worn draw roll, to slip on the glass ribbon, causing adverse effects on the forming quality, and accelerating the wear of the more worn draw roll with the lower linear speed.
FIG. 8B conceptually illustrates the method of assessing the amount of wear. The control device 446 monitors a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll. Afterwards, the control device 446 may assess a first wear amount by which the first draw roll has been worn and a second wear amount by which the second draw roll has been worn based on a comparison between the first electrical driving current and the second electrical driving current. Specifically, one of the draw rolls driven by a lower electrical driving current may be assessed to have been worn more than the other draw roll driven by a higher electrical driving current. Even when the draw rolls 450a, 450b rotate at the same angular speed, a lower degree of torque is applied to the draw roll that has been worn more, thereby consuming a lower amount of electrical driving current. Thus, the draw roll that has been worn more may be determined based on a comparison between the electrical driving currents.
FIG. 9 is a flowchart conceptually illustrating a method of compensating for the difference in wear amounts that has been assessed by the method of FIG. 8B.
As illustrated in FIG. 9, the pull roll device is operated such that the first draw roll 450a rotates in a first rotating condition to draw one surface of the glass ribbon 305 and the second draw roll 450b rotates in a second rotating condition to draw the other surface of the glass ribbon 305. During the operation of the pull roll device, the control device 446 assesses whether or not a first wear amount by which the first draw roll 450a has been worn is substantially different from a second wear amount by which the second draw roll 450b has been worn by comparing the electrical driving current supplied to the first driving device 454a and the electrical driving current supplied to the second driving device 454b. Afterwards, when the first wear amount is assessed to be substantially different from the second wear amount, the control device 446 modifies at least one of the first and second rotating conditions to compensate for the difference between the first wear amount and the second wear amount.
In some embodiments, the first and second rotating conditions may be first and second predetermined angular speeds of the first and second draw rolls 450a, 450b.
In some embodiments, the control device 446 monitors the first electrical driving current supplied to the first driving device 454a to drive the first draw roll 450a and the second electrical driving current supplied to the second driving device 454b to drive the second draw roll 450b. Afterwards, when the difference between the first driving current and the second driving current exceeds a predetermined range, the first wear amount and the second wear amount may be assessed to be substantially different from each other. In this case, the control device 446 may increase the angular speed of the draw roll driven by a lower electrical driving current to be greater than the immediately preceding predetermined angular speed.
In some embodiments, when the first wear amount and the second wear amount are assessed to be substantially different, the control device 446 decreases a predetermined diameter of one of the first and second draw rolls 450a, 450b driven by a lower driving current to be smaller than the immediately preceding predetermined diameter thereof. Here, the predetermined diameter indicates a diameter which the control device 446 recognizes as a current diameter of the first or second draw roll 450a, 450b. Most of the time, the values of the predetermined diameters will be different from the values of the actual diameters thereof. After the first and second draw rolls 450a, 450b have been used for a long time but before the control device 446 updates the values of the predetermined diameters thereof to decrease, the values of the predetermined diameters thereof will be greater than the values of the actual diameters thereof. The values of the predetermined diameters may be initially input manually by an operator and updated manually by an operator or automatically as a result of a difference between the first and second electrical driving currents. Afterwards, in response to the decrease of the diameter of the draw roll driven by the lower driving current, the control device 446 may increase the predetermined angular speed of the draw roll driven by the lower electrical driving current as a function of the predetermined diameter thereof. Since the linear speed of the draw roll, i.e., the speed at which the draw roll draws the glass ribbon, is proportional to a product of the angular speed and the diameter, the increase of the angular speed of the draw roll causes the linear speed of the draw roll that has been worn more to increase.
In some cases, it may be a practical option to replace the draw roll that has been worn more with a new draw roll having a greater diameter than the actual diameter of the more-worn draw roll instead of updating the value of the predetermined diameter of the more-worn draw roll to decrease and then modifying the predetermined angular speed thereof.
FIG. 10 is a flowchart conceptually illustrating a method of assessing a difference between drawing conditions in which the draw rolls 450a, 450b draw the glass ribbon 305 according to some embodiments.
The pull roll device is operated such that the first draw roll 450a rotates to draw one surface of the glass ribbon 305 in a first drawing condition and the second draw roll 450b rotates to draw the other surface of the glass ribbon 305 in a second drawing condition. Afterwards, the control device 446 monitors a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll. Afterwards, the control device 446 may assess the first drawing condition and the second drawing condition based on the first current and the second current.
When the difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, the control device 446 may assess the first drawing condition and the second drawing condition to be substantially different from each other.
Each of the first and second drawing conditions may include i) a drawing force with which the corresponding draw roll of the first and second draw rolls 450a, 450b draws the glass ribbon 305 and ii) a drawing speed at which the corresponding draw roll of the first and second draw rolls 450a, 450b draws the glass ribbon 305.
In some embodiments, the control device 446 may assess the drawing force with which one of the first and second draw rolls 450a, 450b driven by a lower electrical driving current draws the glass ribbon 305 to be less than the drawing force with which the other draw roll draws the glass sheet 305.
Alternatively, the control device 446 may assesses the drawing speed at which the one of the first and second draw rolls 450a, 450b driven by the lower driving current draws the glass ribbon 305 to be less than the drawing speed at which the other draw roll draws the glass ribbon 305.
FIG. 11 is a flowchart conceptually illustrating a method of decreasing the difference between the drawing conditions assessed by the method of FIG. 10 according to some embodiments.
As illustrated in FIG. 11, the pull roll device is operated such that the first draw roll 450a rotates in a first rotating condition to draw one surface of the glass ribbon 305 in a first drawing condition and the second draw roll 450b rotates in a second rotating condition to draw the other surface of the glass ribbon 305 in a second drawing condition. During the operation of the pull roll device, the control device 446 assesses whether or not the first drawing condition and the second drawing condition are substantially different from each other. Afterwards, when the first drawing condition and the second drawing condition are assessed to be substantially different from each other, the control device 446 may modify one of the first drawing condition and the second drawing condition to decrease the difference between the first drawing condition and the second drawing condition.
In some embodiments, the control device 446 may increase the angular speed of one of the first and second draw rolls driven by a lower driving current to be greater than the immediately preceding predetermined angular speed.
Alternatively, the control device 446 may decrease the diameter of the one of the first and second draw rolls driven by the lower driving current to be smaller than the immediately preceding predetermined diameter. Afterwards, in response to the decrease of the diameter, the control device 446 may increase the predetermined angular speed of the draw roll driven by the lower driving current as a function of the predetermined diameter thereof.
FIG. 12 is a flowchart illustrating a specified example of the methods of FIG. 9 and FIG. 11.
Since the scoring operation of the scoring sub-assembly 921 and the engaging operation of the sheet removal sub-assembly 915 act as disturbing factors that influence electrical driving currents, it may be recommended not to use values of electrical driving currents obtained while there are any disturbances. Specifically, no values of electrical driving current obtained and/or obtainable during a separating period when the sheet separating device 900 is in contact with the glass ribbon 305 (in a exemplary embodiment, between a point in time at which a signal indicating the start of the engagement operation of the sheet removal sub-assembly 915 is input to the control device 446 and a point in time at which a signal indicating the start of the returning operation of the scribe transporter 927 of the scoring sub-assembly 921 is input to the control device 446) are used in the assessment of wear amount and the assessment of drawing conditions. Instead, the control device 446 may monitor the driving currents during a preparation period when the sheet separating device 900 is not in contact with the glass ribbon 305, and then, perform the assessment using only the electrical driving currents obtained during the preparation period.
In some embodiments, values of driving currents supplied to the driving devices may be obtained as follows: i) the control device 446 may monitor a first series of electrical driving currents and a second series of electrical driving currents supplied to the first driving 454a device and the second driving device 454b, respectively, at regular intervals in every period in which a single glass sheet is produced. When the first series of electrical driving currents and the second series of electrical driving currents, that is, a predetermined number (e.g., sixty) of driving current values and a predetermined number (e.g., sixty) of driving current values are collected, the control device 446 may calculate the moving averages thereof, and then use the obtained average electrical driving current values in the assessment of wear amount and the assessment of drawing conditions.
The control device 446 may calculate a difference in electrical driving current values, i.e. the difference between a first electrical driving current (the average of the first series of electrical driving currents in the embodiments as described above) supplied to the first driving device 454a and a second electrical driving current (the average of the second series of electrical driving currents in the embodiments as described above) supplied to the second driving device 454b, and then, compare the first and second electrical driving currents with each other to determine whether or not the difference in driving current values exceeds a predetermined difference range. The control device 446 may assess one of the two draw rolls 450a, 450b driven by a lower driving voltage to have been worn more than the other draw roll. When the difference between the respective electrical driving current values is smaller than or equal to the predetermined difference range, the control device 446 may wait for the next point in time of comparison. In contrast, when the difference in electrical driving current values is greater than the predetermined difference range, the predetermined diameter of the draw roll driven by a higher electrical driving current remains unchanged, while the control device 446 may identify the draw roll driven by a lower electrical driving current as a more worn draw roll and decrease the predetermined diameter thereof by a predetermined amount (e.g. 0.0005”).
In some embodiments, the glass manufacturing apparatus 300 may be configured to sequentially repeat the assessment operation by which the drawing conditions, the wear amounts, and/or the driving currents are assessed and the modification operation by which at least one of the first and second rotating conditions is modified, as described above. Here, the control device 446 may terminate the repetition without proceeding to the modification operation when a difference between the first electrical driving current and the second electrical driving current is determined to continue to increase while the modification operation by which the at least one of the first and second rotating conditions is modified is repeated a predetermined number of times.
In an exemplary embodiment, when the predetermined diameter has been modified by the immediately preceding modification operation, the control device 446 observes a change in the difference in electrical driving current values. When the new difference is smaller than or equal to the immediately preceding difference, the control device 446 initializes the count number as zero (0). In contrast, when the new difference is greater than the immediately preceding difference, the control device 446 increases the count number by 1. When the count number reaches a predetermined value (e.g., 5), the difference in electrical driving current values is interpreted as gradually increasing. In this case, the control device 446 may terminate the control process for compensating for wear and decreasing differences in drawing conditions.
FIG. 13A and FIG. 13B are charts illustrating differences between values of electrical driving currents obtained for a relatively short period of time, before and after the method of FIG. 12 is implemented.
As illustrated in FIG. 13A and FIG. 13B, before the exemplary method was implemented, the values of a first electrical driving current DC1 (maximum 0.075 and minimum -0.15) were significantly smaller than the values of a second electrical driving current DC2 (maximum 0.275 and minimum 0.075). In contrast, after the exemplary method was implemented, the values of the first electrical driving current DC1 (maximum 0.15 and minimum -0.08) became substantially the same as the values of the second electrical driving current DC2 (maximum 0.275 and minimum 0.075).
FIG. 14A and FIG. 14B are charts illustrating differences between values of drawing forces obtained for a relatively long period of time, before and after the method of FIG. 12 is implemented.
As illustrated in FIG. 14A and FIG. 14B, before the exemplary method was implemented, a first drawing force DF1 was significantly less than a second drawing force DF2. In contrast, after the exemplary method was implemented, the first drawing force DF1 became substantially the same as the second drawing force DF2.
According to the present disclosure, it is possible to compensate for the difference in the amount of wear between the draw rolls in real time by repeatedly monitoring changes in the electrical driving currents supplied to the driving devices during a period in which a single glass sheet is produced. It is thereby possible to ensure reducing a difference in operation parameters due to different amounts of wear of the draw rolls, even if the actual diameter of the first draw roll is substantially different from the diameter of the second draw roll.
In addition, after the draw rolls had been used for a prolonged period of time, the forming quality became worse and it was found that the difference between drawing forces increased. After the difference between the amounts of wear is compensated for, the difference between drawing forces can continuously remain at a level measured directly after the replacement of the draw rolls, thereby increasing the lifespans of the drawing rolls.
The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented with respect to the drawings. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed herein, and many modifications and variations are obviously possible for a person having ordinary skill in the art in light of the above teachings.
It is intended therefore that the scope of the present disclosure not be limited to the foregoing embodiments, but be defined by the Claims appended hereto and their equivalents.

Claims (34)

  1. A method of manufacturing a glass ribbon, comprising:
    a) forming a glass ribbon having a width;
    b) operating a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
    c) assessing whether the first and second drawing conditions are substantially different from each other; and
    d) modifying at least one of the first and second rotating conditions to decrease a difference between the first and second drawing conditions when the first and second drawing conditions are assessed to be substantially different from each other.
  2. The method of claim 1,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first drawing condition comprises a first drawing force with which the first draw roll draws the one surface of the glass ribbon and the second drawing condition comprises a second drawing force with which the second draw roll draws the other surface of the glass ribbon,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises:
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first drawing force and the second drawing force to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, and
    wherein step d) comprises increasing the predetermined angular speed of one draw roll of the first and second draw rolls driven by a lesser electrical driving current.
  3. The method of claim 1,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first drawing condition comprises a first drawing force with which the first draw roll draws the one surface of the glass ribbon and the second drawing condition comprises a second drawing force with which the second draw roll draws the other surface of the glass ribbon,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises:
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first drawing force and the second drawing force to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, and
    wherein step d) comprises:
    d1) decreasing a predetermined diameter of one draw roll of the first and second draw rolls driven by a lesser electrical driving current; and
    d2) increasing, in response to the decrease of the predetermined diameter of the one draw roll, the predetermined angular speed of the one draw roll as a function of the predetermined diameter thereof.
  4. The method of claim 1,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first drawing condition comprises a first drawing speed at which the first draw roll draws the one surface of the glass ribbon and the second drawing condition comprises a second drawing speed at which the second draw roll draws the other surface of the glass ribbon,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises:
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first drawing speed and the second drawing speed to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, and
    wherein step d) comprises increasing the predetermined angular speed of one draw roll of the first and second draw rolls driven by a lesser driving current.
  5. The method of claim 1,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first drawing condition comprises a first drawing speed at which the first draw roll draws the one surface of the glass ribbon and the second drawing condition comprises a second drawing speed at which the second draw roll draws the other surface of the glass ribbon,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises:
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first drawing speed and the second drawing speed to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, and
    wherein step d) comprises:
    d1) decreasing a predetermined diameter of one draw roll of the first and second draw rolls driven by a lesser driving current; and
    d2) increasing, in response to the decrease of the predetermined diameter of the one draw roll, the predetermined angular speed of the one draw roll as a function of the predetermined diameter thereof.
  6. A method of manufacturing a glass ribbon, the method comprising:
    a) forming a glass ribbon having a width;
    b) operating a pull roll device comprising at least one pair of draw rolls, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
    c) assessing whether a first wear amount of the first draw roll by which the first draw roll has worn away is substantially different from a second wear amount of the second draw roll by which the second draw roll has worn away, and
    d) modifying at least one of the first and second rotating conditions to compensate for a difference between the first wear amount and the second wear amount when the first wear amount and the second wear amount are assessed to be substantially different from each other.
  7. The method of claim 6,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises,
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first wear amount and the second wear amount to be substantially different from each other when a difference between the first driving current and the second driving current exceeds a predetermined range, and
    wherein step d) comprises increasing the predetermined angular speed of one draw roll of the first and second draw rolls driven by a lesser driving current.
  8. The method of claim 6,
    wherein the pull roll device further comprises a first driving device to drive the first draw roll to rotate in the first rotating condition and a second driving device to drive the second draw roll to rotate in the second rotating condition,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively,
    wherein step c) comprises:
    c1) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c2) assessing the first wear amount and the second wear amount to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range, and
    wherein step d) comprises:
    d1) decreasing a predetermined diameter of one draw roll of the first and second draw rolls driven by a lesser driving current; and
    d2) increasing, in response to the decrease of the predetermined diameter of the one draw roll, the predetermined angular speed of the one draw roll as a function of the predetermined diameter thereof.
  9. A method of assessing drawing conditions, comprising:
    a) operating q pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet in a first drawing condition and the second draw roll rotates to draw the other surface of the sheet in a second drawing condition;
    b) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c) assessing the first and second drawing conditions based on the first and second driving currents.
  10. The method of claim 9,
    wherein each of the first and second drawing conditions comprises a drawing force with which a corresponding draw roll of the first and second draw rolls draws the sheet, and
    wherein step c) comprises assessing the drawing force with which one draw roll of the first and second draw rolls driven by a lesser driving current draws the sheet to be less than the drawing force with which the other draw roll draws the sheet.
  11. The method of claim 9,
    wherein each of the first and second drawing conditions comprises a drawing speed at which a corresponding draw roll of the first and second draw rolls draws the sheet, and
    step c) comprises assessing the drawing speed at which one draw roll of the first and second draw rolls draws the sheet to be less than the drawing speed at which the other draw roll draws the sheet.
  12. A method of assessing amounts of wear of draw rolls, comprising:
    a) operating a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll, to draw a sheet having a width along a draw path extending transverse to the width such that the first draw roll rotates to draw one surface of the sheet and the second draw roll rotates to draw the other surface of the sheet;
    b) monitoring a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll; and
    c) assessing a first wear amount of the first draw roll by which the first draw roll has worn away and a second wear amount of the second draw roll by which the second draw roll has worn away, based on the first and second driving currents.
  13. The method of claim 12,
    wherein step d) comprises assessing the wear amount of one draw roll of the first and second draw rolls driven by a lesser electrical driving current to be greater than the wear amount of the other draw roll.
  14. A method of manufacturing a glass ribbon, comprising:
    a) forming a glass ribbon having a width;
    b) operating a pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device driving the first draw roll and a second driving device driving the second draw roll, to draw the glass ribbon along a draw path extending transverse to the width such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon;
    c) determining whether a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
    d) modifying at least one of the first and second rotating conditions when the first and second driving currents are determined to be substantially different from each other.
  15. The method of claim 14,
    wherein step c) determines the first electrical driving current and the second electrical driving current to be substantially different from each other when a difference between the first electrical driving current and the second electrical driving current exceeds a predetermined range.
  16. The method of claim 14,
    wherein step c) comprises:
    c1) monitoring a first series of electrical driving currents supplied to the first driving device and a second series of electrical driving currents supplied to the second driving device, respectively, at regular intervals;
    c2) averaging the first series of electrical driving currents and the second series of electrical driving currents; and
    c3) performing the determination using the average of the first series of electrical driving currents and the average of the second series of electrical driving currents as the first electrical driving current and the second electrical driving current, respectively.
  17. The method of claim 14,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively, and
    step d) comprises increasing the predetermined angular speed of one draw roll of the first and second draw rolls driven by a lesser driving current.
  18. The method of claim 14,
    wherein step d) comprises:
    d1) decreasing a predetermined diameter of one draw roll of the first and second draw rolls driven by a lower driving current.
  19. The method of claim 18,
    wherein, in step d1), the predetermined diameter of the one draw roll is decreased by a predetermined amount.
  20. The method of claim 18,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively, and
    wherein step d) further comprises: after step d1),
    d2) increasing, in response to the decrease of the predetermined diameter of the one draw roll, the predetermined angular speed of the one draw roll as a function of the predetermined diameter thereof.
  21. The method of claim 14,
    further comprising: separating at least one glass sheet from the glass ribbon using a sheet separating device,
    the sheet separating device comprising a separating period when the sheet separating device is in contact with the glass ribbon and a preparation period when the sheet separating device is released from the glass ribbon, and
    wherein step c) comprises :
    c1) monitoring the first and second electrical driving currents during the preparation period of the sheet separating device, and
    c2) performing the determination using the first and second electrical driving currents monitored during the preparation period of the sheet separating device.
  22. The method of claim 14,
    further comprising: repeating steps c) and d),
    wherein step c) comprises terminating the repetition without proceeding to step d) when a difference between the first electrical driving current and the second electrical driving current is determined to continue to increase while step d) by which the at least one of the first and second rotating conditions is modified is repeated a predetermined number of times.
  23. A glass manufacturing apparatus comprising:
    a forming device configured to form a glass ribbon having a width;
    a pull roll device configured to draw the glass ribbon along a draw path extending transverse to the width from the forming device, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll; and
    a control device configured to:
    operate the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
    determine whether a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
    modify at least one of the first and second rotating conditions when the first electrical driving current and the second electrical driving current are determined to be substantially different from each other.
  24. The glass manufacturing apparatus of claim 23,
    wherein the control device is configured to assess the first and second drawing conditions to be substantially different from each other when a difference between the first and second driving currents exceeds a predetermined range.
  25. The glass manufacturing apparatus of claim 23,
    wherein the control device is configured to:
    monitor a first series of electrical driving currents supplied to the first driving device and a second series of electrical driving currents supplied to the second driving device, respectively, at regular intervals;
    average the first series of driving currents and the second series of driving currents; and
    perform the determination using the average of the first series of electrical driving currents and the average of the second series of electrical driving currents as the first electrical driving current and the second electrical driving current, respectively.
  26. The glass manufacturing apparatus of claim 23,
    wherein the first and second rotating conditions comprise predetermined angular speeds of the first and second draw rolls, respectively, and
    wherein the control device is configured to increase the predetermined angular speed of one draw roll of the first and second draw rolls driven by a lower driving current.
  27. The glass manufacturing apparatus of claim 23,
    wherein the control device is configured to decrease a predetermined diameter of one draw roll of the first and second draw rolls driven by a lower driving current.
  28. The glass manufacturing apparatus of claim 27,
    wherein the control device is configured to decrease the predetermined diameter of the one draw roll by a predetermined amount.
  29. The glass manufacturing apparatus of claim 27,
    wherein the first and second rotating conditions comprise angular speeds of the first and second draw rolls, respectively, and
    wherein the control device is configured to increase, in response to the decrease of the predetermined diameter of the one draw roll, the predetermined angular speed of the one draw roll as a function of the predetermined diameter thereof.
  30. The glass manufacturing apparatus of claim 23,
    further comprising: a sheet separating device configured to separate at least one glass sheet from the glass ribbon, the sheet separating device comprising a separating period when the sheet separating device is in contact with the glass ribbon and a preparation period when the sheet separating device is released from the glass ribbon,
    wherein the control device is configured to
    monitor the first and second electrical driving currents during the preparation period of the sheet separating device; and
    perform the determination using the first and second electrical driving currents monitored during the preparation period of the sheet separating device.
  31. The glass manufacturing apparatus of claim 23,
    wherein the control unit is configured to
    repeat the determination and the modification; and
    terminate the repetition without proceeding to the modification when a difference between the first driving current and the second driving current continues to increase while the modification is repeated a predetermined number of times.
  32. The glass manufacturing apparatus of claim 23,
    wherein the first and second draw rolls are disposed on one of two edge portions of the glass ribbon between which the width extends such that the glass ribbon is drawn between the first and second draw rolls.
  33. The glass manufacturing apparatus of claim 23,
    wherein the at least one pair of draw rolls comprise at least one row of draw roll pairs, the at least one row of draw roll pairs comprising two pairs of draw rolls disposed on two edge portions of the glass ribbon, respectively.
  34. A pull roll apparatus comprising:
    a pull roll device configured to draw a glass ribbon having a width along a draw path extending transverse to the width, the pull roll device comprising at least one pair of draw rolls and at least one pair of driving devices, the at least one pair of draw rolls comprising a first draw roll and a second draw roll, the at least one pair of driving devices comprising a first driving device to drive the first draw roll and a second driving device to drive the second draw roll; and
    a control device configured to:
    operate the pull roll device such that the first draw roll rotates in a first rotating condition to draw one surface of the glass ribbon in a first drawing condition and the second draw roll rotates in a second rotating condition to draw the other surface of the glass ribbon in a second drawing condition;
    determine whether a first electrical driving current supplied to the first driving device to drive the first draw roll and a second electrical driving current supplied to the second driving device to drive the second draw roll are substantially different from each other; and
    modify at least one of the first and second rotating conditions when the first electrical driving current and the second electrical driving current are determined to be substantially different from each other.
PCT/KR2017/005340 2016-05-23 2017-05-23 Glass manufacturing apparatus and method WO2017204526A1 (en)

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WO2017204526A8 (en) 2017-12-28

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