Classifications

• • 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
  • 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
• • 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
  • C03B33/023—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor the sheet or ribbon being in a horizontal position
  • C03B33/033—Apparatus for opening score lines in glass sheets
• • 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
  • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

• the present specification generally relates to methods and devices for flattening glass sheets and, more particularly, to devices for flattening thin glass sheets near a score head assembly.
• Continuous glass ribbons may be formed by processes such as the fusion draw process or other, similar down draw processes.
• the fusion draw process yields continuous glass ribbons which have surfaces with superior flatness and smoothness when compared to glass ribbons produced by other methods.
• Individual glass sheets sectioned from continuous glass ribbons formed by the fusion draw process can be used in a variety of devices including flat panel displays, touch sensors, photovoltaic devices, and other electronic applications.
• Continuous glass ribbons whether formed by the fusion draw process or otherwise, often bow or curve in a lateral direction due to temperature gradients in the glass as it cools, such as temperature gradients between a glass sheet bead and a center area of the glass sheet.
• the distortion of the glass sheet may be exacerbated when the glass sheet is thin, such as 1 mm or less, as the thin center area may cool more quickly than the bead portion.
• the beads may be sectioned from the glass sheet by supporting the glass sheet with a suction apparatus as the glass sheet is scored and the beads are separated along the scoring line.
• the suction apparatus may create a mechanical stress field, like a "bulls-eye", due to the localized sheet deformation.
• This stress field may be located near the score line and, thus, may pull the score line away from the scored median crack, thereby causing sheet breakage.
• the contact between the scoring device and the curved glass sheet may also introduce motion in the glass sheet that is propagated upstream of the scoring device and causes undesirable stress and warp in the sheet.
• An objective when scoring a glass sheet for bead removal is to produce a uniform median vent simultaneously at both the vertical bead scoring machine inlet and at positions where the glass sheet is supported, such as by suction.
• the median crack depth may be easily controlled by applying a stable force to the score wheel.
• the vent depth cannot be controlled using a stable force. Clamping has a limited effect on flattening the score line due to the length of the sheet and friction of a clamping nosing needed to resist sheet movement.
• a method for scoring a glass sheet comprising a flattening device and a scoring apparatus may be positioned at or near one end of the glass sheet.
• the flattening device may then be extended toward the glass sheet so that the flattening device is in moveable contact with the glass sheet.
• a portion of the glass sheet may be flattened by moving the flattening apparatus along a length of the glass sheet to an opposite end of the glass sheet, and the portion of the glass sheet may be scored by moving the scoring apparatus along a length of the glass sheet to the opposite end of the glass sheet.
• the flattening device may be retracted so that it is no longer in contact with the glass sheet.
• the flattening apparatus and the scoring apparatus may then be repositioned at or near the one end of the glass sheet. According embodiments of this method, the flattening apparatus flattens the portion of the glass sheet before the portion of the glass sheet is scored.
• FIG. 1 is a schematic diagram of a glass fabrication apparatus according to embodiments
• FIG. 2 is a schematic diagram of a glass ribbon formed by a drawing process according to embodiments
• FIG. 3 is a schematic side view of a vertical bead scoring machine according to embodiments
• FIGS. 6A - 6C are schematics of flattening wheels according to embodiments.
• FIG. 7 is a schematic of a glass manufacturing system using a vertical bead scoring machine to separate a glass bead of a glass sheet from the glass sheet according to embodiments.
• FIG. 1 shows a fusion process according to embodiments that employs a forming structure 37, which receives molten glass (not shown) in a cavity 39.
• the forming structure 37 may include root 41 where molten glass from the forming structure's two converging sides join together to form a continuous glass ribbon 15.
• the ribbon After leaving the root, the ribbon first traverses edge rollers 27 and then pulling rolls 29. As it moves down the draw, the glass passes through its glass transition temperature region (GTTR), shown schematically at 31 in FIG. 1. At temperatures above the GTTR, the glass behaves basically like a viscous liquid. At temperatures below the GTTR, the glass behaves basically like an elastic solid.
• GTTR glass transition temperature region
• the glass cools from a high temperature through its GTTR it does not show an abrupt transition from viscous to elastic behavior. Instead, the viscosity of the glass gradually increases, and goes through a visco-elastic regime where both viscous and elastic responses are noticeable, and eventually it behaves as an elastic solid.
• the GTTR may vary with the particular composition of the glass being processed, as representative values the upper end of the GTTR may be less than or equal to about 850°C and the lower end of the GTTR may be greater than or equal to about 650°C. In embodiments, the lower end of the GTTR may be greater than or equal to about 700°C.
• the ribbon may include outer edges 19a, 19b, a centerline 17, and bead portions 21a, 21b, which may extend inward from edges 19a, 19b towards the centerline.
• the thickest part of the bead portion may be present along line 23a (line 23b) and the inner extent of the bead portion may be taken to be present along line 25a (line 256), where the final thickness of the ribbon first rises above 1.05*t cen ter, where t cen ter is the final thickness of the ribbon along the centerline.
• a thickness of 1.05*t cen ter may be considered to be a quality or near quality thickness. Thereafter, the thickness may decrease slightly as the glass cools based on the glass' coefficient of thermal expansion (CTE).
• bead portions 21a and 21b are shown as being symmetric in FIG. 2, in embodiments they may have different widths and the locations of their thickest parts may be different for the two beads. For example, in embodiments neither thickest part need be at the center of the bead portion.
• the cross-draw thickness profile of the continuous glass ribbon 15 is non-uniform, where bead portions of the glass may be thicker than the center.
• the bead portion of the glass may be thicker than the center by a factor of 2 or more. This may result in a temperature profile that contains a local maxima in the bead portion and, for most of the ribbon length, the bead may be relatively hotter compared to the centerline. High temperatures in the bead portions may cause undesirable stresses and undesirable shapes in both the ribbon and the final glass product. These stresses may result in distortions in the shape of the ribbon which can adversely impact scoring processes used during bead removal.
• the apparatus and methods disclosed below provide a stable shape in the bead portion when scoring the bead portions to be removed from the ribbon.
• the nosing may be positioned such that a glass sheet 340 may be inserted into the glass conveyance pathway 346 formed between the nosing 345 and the flattening apparatus 310 and between the nosing 345 and the scoring apparatus 320.
• the scoring apparatus 320 or the flattening apparatus 310 may apply a force to a glass sheet such that the glass sheet is impinged between the flattening apparatus 310 and the nosing, thereby flattening and supporting the glass sheet during the flattening and/or scoring process.
• the glass conveyance pathway 346 may be vertically oriented.
• the VBS 300 may be constructed with a different scoring linkage than that depicted in FIG. 3, or even without a scoring linkage, such as when the flattening apparatus 310 and the scoring apparatus 320 are separate devices.
• the flattening apparatus 310 generally comprises a support frame 311, a flattening wheel 312, an actuator 313, and a slide mechanism 314.
• the axis of rotation of the flattening wheel 312 may be horizontally oriented, as shown in FIG. 3.
• it should be understood that other configurations of the flattening apparatus are possible.
• the support frame 311 may be formed from any suitable rigid or semi-rigid material.
• the support frame 31 1 may be made of metal, such as steel or aluminum.
• the support frame 311 may be made of plastic or a polymer.
• the support frame 311 may be a bracket that supports at least one of the actuator 313 and/or the slide mechanism 314.
• the support frame 311 may be attached to the scoring bar linkage 330, for example by bolts or rivets, allowing the support frame 311 to move in a vertical direction (i.e., in the +/- y-direction) with the scoring apparatus 320.
• the support frame 311 and the scoring apparatus 320 may be moved simultaneously in the vertical direction by other mechanisms without deviating from the scope of this disclosure.
• the flattening apparatus 310 may comprise an actuator 313 that moves the flattening wheel 312 in the lateral direction (i.e., +/- x-direction).
• the embodiment shown in FIG. 3 depicts the actuator 313 as a low- friction air cylinder.
• the actuator may comprise hydraulic cylinders, pneumatic cylinders, motor driven linear actuators, or similar linear actuators that are used to move the flattening wheel 312 in a lateral direction.
• the actuator 313 is shown as a low- friction air cylinder that may have a piston 410 mechanically coupled to a shaft 430.
• the shaft 430 may be extended or retracted by controlling the amount of air or compressed fluid supplied to low- friction air cylinder 313.
• the actuator 313 is an Airpel low friction cylinder with a 1 inch stroke length and a 16 mm bore manufactured by Airpot Corporation.
• a bracket 420 may connect the low-friction air cylinder 313 to the scoring bar linkage 330.
• a first end of the low- friction air cylinder 313 may be fixedly attached to the base of the support frame 311.
• the second end of low- friction air cylinder 313 (e.g., the shaft end) may be attached to the flattening wheel 312, which is moveably attached to the support frame 311.
• the flattening wheel mechanism may comprise support structures 450 that connect the flattening wheel 312 to the low- friction air cylinder 313.
• the support structures 450 may include the slide mechanism 414, and may be in any configuration that places the flattening wheel 312 in the desired position relative to the scoring apparatus 320, the nosing 345, and the glass conveyance pathway 346.
• the slide mechanism 414 may be slideably attached to the support frame 311 and may be connected to the flattening wheel 312.
• the slide mechanism 414 moves in a lateral direction (i.e., +/- x-direction of FIG.
• the support frame 311 may comprise a convex portion and the slide mechanism 414 may comprise a concave portion configured to accept the convex portion of the support frame 311.
• the slide mechanism moves in the lateral direction it may be supported and/or guided by the convex portion of the support frame.
• the scoring apparatus 320 may include a score head 321.
• a score wheel turret 322 may be positioned at the end of the score head 321 and comprises a scoring wheel 323 that may be positioned in the glass conveyance pathway 346 and may score a glass sheet 340 at a position adjacent to the bead portion of the glass sheet.
• the axis of rotation of the scoring wheel 323 may be horizontally oriented, as shown in FIG. 3.
• the score wheel turret 322 may comprise multiple scoring wheels 323 (five depicted in FIG. 3) with a pivot 324 around which the score wheel turret 322 rotates.
• the score wheel turret 322 may be configured such that a predetermined rotation of the score wheel turret 322 around the pivot 324 allows a different scoring wheel 323 to be positioned to in the glass conveyance pathway 346.
• other embodiments need not include a score wheel turret 322, such as when the scoring apparatus comprises a single score wheel. Accordingly, it should be understood that other configurations of the scoring apparatus are possible and contemplated.
• the scoring apparatus 320 comprises a mechanical scoring device, such as a scoring wheel or scoring point.
• the scoring apparatus 320 may comprise a laser scoring device.
• the scoring apparatus 320 may be coupled to an actuator (not shown) that is operable to traverse the scoring apparatus 320 in the +/- y-direction.
• the scoring apparatus may also be coupled to an actuator (not shown) which facilitates positioning the scoring apparatus in the +/- x-direction as the scoring apparatus 320 is traversed in the +/- y-direction.
• the flattening wheel may have any suitable geometry for flattening portions of a sheet of glass sheet 340 prior to scoring the sheet of glass sheet 340.
• the flattening wheel 312 may be cylindrical and may have a diameter from about 0.50 inches to about 1.50 inches. In some embodiments, the diameter of the flattening wheel 312 may be from about 0.75 inches to about 1.25 inches, or even 1.00 inch.
• the flattening wheel 312 may have a width from about 0.25 inches to about 1.00 inches. In other embodiments, the flattening wheel may have a width from about 0.33 inches to about 0.75 inches, or even 0.50 inches. In some embodiments, the flattening wheel may have Shore A hardness of 90.
• a flattening wheel with a single o-ring may flatten the score line of the glass sheet by positioning the o-ring over the location of a score line.
• a flattening wheel with two o-rings may flatten areas on both sides of the score line by positioning the score line between the two o-rings.
• a flattening wheel with three o-rings may flatten the score line and the area on both sides of the score line by positioning the score line at the middle of the three o-rings.
• the o-rings may have any suitable geometry.
• the o-rings may be round or square in various embodiments. Round o-rings may provide minimal contact and, thus, minimal friction, with the glass sheet 340.
• Square o-rings may provide maximum contact and, thus, maximum friction, with the glass sheet 340. Accordingly, the o-ring geometry may be selected according to the desired friction between the flattening wheel 312 and the glass sheet 340. As noted hereinabove with respect to the flattening wheel, the hardness of the o- rings may be selected based on the thickness of the glass sheet which the o-rings contact.
• VBS 300 depicted in FIG. 3 is one embodiment of a VBS suitable for use in conjunction with the methods for separating beads of glass sheets from the glass sheet that will be described in more detail herein.
• VBSs may also be used.
• VBSs having two flattening wheels, as shown in FIG. 5 may be used.
• the clamp bars clamp the entire edge of the glass sheet from top to bottom such that the surface of the glass sheet is in a single plane.
• pockets of non-uniformity i.e., warp or distortion
• the use of the flattening rollers counteracts this problem.
• the pull roll assembly 740 delivers the drawn continuous glass ribbon 15 (which at this point in the manufacturing process has a curved/bowed shape) to the sheet separation apparatus 761.
• the continuous glass ribbon 15 is delivered to the sheet separation apparatus 761, which separates the glass sheet from the ribbon.
• the configuration of the sheet separation apparatus is not particularly limited. An exemplary embodiment of a sheet separation apparatus is disclosed in U.S. Patent No. 8,146,385, which is incorporated herein by reference in its entirety.
• the carriage then transfers the glass sheet to the VBS to remove the glass bead from the glass sheet.
• a VBS as shown in FIG. 3 may be used to remove the glass bead from the glass sheet.
• the glass sheet entering the VBS may be cooling, and may have a temperature of from room temperature to about 450°C, or even from about 100°C to about 400°C. In some embodiments, the glass sheet may have a temperature of from about 150°C to about 350°C, or even 200°C to about 300°C when it enters the VBS.
• the method of using the VBS 300 to separate the bead of a glass sheet from the glass sheet 340 will now be described in more detail with reference to FIG. 3.
• the scoring apparatus 320 may be located above the top of the glass sheet 340 in the y-direction, as shown in FIG. 3.
• the shaft of the flattening apparatus is extended, thereby causing the slide mechanism 314 to move in the positive x-direction.
• the actuator 313 is a low-friction air cylinder 313
• the shaft is extended by supplying air pressure to the low- friction air cylinder.
• the low-friction air cylinder may be extended to about the middle of its stroke. The extension of the low-friction air cylinder causes the flattening wheel 312 to be moveably engaged with the glass sheet 340.
• the pressure applied to the glass sheet 340 by the flattening wheel 312 may vary depending on the composition and thickness of the glass, the amount of curvature or distortion to be removed, the wheel geometry, the wheel durometer, sheet stiffness, and the desired scoring regime (i.e., tension or compression).
• the pressure applied by the flattening wheel may be from about 10 psi to about 30 psi, or even from about 15 psi to about 25 psi.
• the pressure applied to the glass sheet 340 by the flattening wheel 312 may be about 20 psi.
• the VBS may be moved in the negative y-direction, thus causing the flattening wheel 312 to engage a portion of the glass sheet 340 before is the glass sheet 340 is scored by the scoring wheel 323.
• the scoring apparatus 320 and the flattening apparatus 310 may be connected by a scoring bar linkage 330. Thus, the scoring apparatus 320 and the flattening apparatus 310 travel along the glass sheet at the same velocity and at constant relative positions.
• a vent may be defined as an indentation line formed in the sheet surface that opens that surface to a certain depth.
• the vent line may extend into a surface of the glass sheet to a vent depth equal to the depth of the surface compression layer, but less than the depth that will cause a fracture in the glass sheet.
• the vent may extend in a vertical direction from one end of the glass sheet to the other end of the glass sheet.
• the low- friction air cylinder 313 is retracted, thus causing the slide mechanism 314 and the flattening wheel 312 to move in the negative x-direction so that the flattening wheel 312 is no longer in contact with the glass sheet 340.
• the scoring wheel 323 may be retracted so that it no longer contacts the glass sheet.
• the scoring apparatus 320 and the flattening apparatus 310 may then be moved in the positive y-direction to their original positions at or near the top of the glass sheet 340 without contacting the glass sheet.
• the glass sheet may then be removed from the VBS, and a new glass sheet may enter the VBS.
• the VBS 300 may be moved in the y-direction by any suitable mechanism.
• the flattening apparatus 310 and the scoring apparatus 320 may be moved in the y-direction by an electro-mechanical actuator, a pneumatic cylinder, a hydraulic cylinder, or an electric motor.
• the VBS 300 may be positioned with a robotic device, such as a robotic arm.
• the movement of the flattening apparatus 310 and the scoring apparatus 320 in the y-direction and extension and retraction of the low- friction air cylinder may be synchronized with the separation of discrete glass sheets from a continuous glass ribbon, such as when the VBS and the glass separation apparatus are controlled with a common controller or separate controllers synchronized with one another.
• the methods for separating the bead of a glass sheet from a glass sheet may be used in conjunction with glass sheets having thickness less than about 1.00 mm, or even less than about 0.75 mm. In some embodiments, the thickness of the glass sheet may be less than about 0.50 mm, or even less than about 0.30 mm.
• the VBS 300 and methods described in embodiments may be used with glass sheets of any thickness, using the VBS and methods with thin glass sheets may provide high yields (i.e., low occurrences of glass fracturing). For example, typical yields when using thin glass, such as 0.3t glass, may be about 30%. Yields using the VBS and methods described herein results in yields of about 80% or greater, even up to 90%>. It should also be understood, however, that the techniques described herein may also be suitable for use in conjunction with glass sheets having thicknesses greater than 1.00 mm.
• the methods described herein may be used to separate beads of glass sheets from glass sheets, such as glass sheets produced with the fusion draw process or similar down draw processes. It should be understood that stresses, deformation and potential breakage of the glass sheets during scoring can be substantially mitigated or eliminated by engaging the flattening wheel with the glass sheet prior to scoring the glass sheet, as described herein. Accordingly, it should be understood that the methods described herein may be utilized to reduce the occurrence of breakage in the glass sheets and thereby reduce waste and improve the throughput of a glass manufacturing system. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

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

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• 2013
  • 2013-12-03 JP JP2015546540A patent/JP6392238B2/ja active Active
  • 2013-12-03 KR KR1020157017752A patent/KR102154544B1/ko active IP Right Grant
  • 2013-12-03 WO PCT/US2013/072712 patent/WO2014088985A1/en active Application Filing
  • 2013-12-03 CN CN201380072062.7A patent/CN105073661B/zh active Active
  • 2013-12-06 TW TW102144871A patent/TWI624437B/zh active

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