WO2014088985A1

WO2014088985A1 - Device for glass sheet flattening and method of flattening a sheet of glass

Info

Publication number: WO2014088985A1
Application number: PCT/US2013/072712
Authority: WO
Inventors: James William BROWN; Nicholas Dominic CAVALLARO, III; Zung-Sing Chang; Keith Mitchell HILL; Naiyue Zhou
Original assignee: Corning Incorporated
Priority date: 2012-12-07
Filing date: 2013-12-03
Publication date: 2014-06-12
Also published as: KR102154544B1; CN105073661A; JP6392238B2; TW201429900A; CN105073661B; KR20150093199A; TWI624437B; JP2016501180A

Abstract

A glass sheet scoring machine comprises a scoring apparatus, a flattening apparatus, including a flattening device, and a scoring bar linkage that functionally connects the scoring apparatus and the flattening apparatus. The flattening device may contact the glass sheet at or near a portion of the glass sheet that is to be scored before the scoring apparatus scores the glass sheet. A method of separating glass bead of a glass sheet from the glass sheet including flattening the glass sheet with a flattening device and scoring the glass sheet with a scoring apparatus.

Description

DEVICE FOR GLASS SHEET FLATTENING AND METHOD OF

FLATTENING A SHEET OF GLASS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 61/734,623 filed on December 7, 2012 the contents of which are relied upon and incorporated herein by reference in their entirety as if fully set forth below.

BACKGROUND

Field

[0002] 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.

Technical Background

[0003] 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.

[0004] 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. After the glass ribbon is drawn, and the glass sheets are separated from the glass ribbon, 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. On a flat sheet, the median crack depth may be easily controlled by applying a stable force to the score wheel. However, when scoring on glass with deformations, 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.

[0005] Accordingly, a need exists for alternative methods of stabilizing a glass sheet during bead scoring.

SUMMARY

[0006] According to one embodiment, a glass sheet scoring machine comprises a scoring apparatus, a flattening apparatus, including a flattening device, and a scoring bar linkage that functionally connects the scoring apparatus and the flattening apparatus. The flattening device may contact the glass sheet at or near a portion of the glass sheet that is to be scored before the scoring apparatus scores the glass sheet.

[0007] In another embodiment, a method for scoring a glass sheet is provided. A flattening apparatus 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. After the movement is complete, 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. [0008] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description that follows, the claims, as well as the appended drawings.

[0009] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a schematic diagram of a glass fabrication apparatus according to embodiments;

[0011] FIG. 2 is a schematic diagram of a glass ribbon formed by a drawing process according to embodiments;

[0012] FIG. 3 is a schematic side view of a vertical bead scoring machine according to embodiments;

[0013] FIG. 4 is a schematic of a flattening apparatus according to embodiments;

[0014] FIG. 5 is a schematic of a flattening apparatus including a trailing flattening wheel according to embodiments;

[0015] FIGS. 6A - 6C are schematics of flattening wheels according to embodiments; and

[0016] 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. DETAILED DESCRIPTION

[0017] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0018] 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. Although it should be understood that other forming techniques may be used. 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. As 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.

[0019] Although 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.

[0020] Edge rollers 27 may contact the continuous glass ribbon 15 at a location above the GTTR while pulling rolls 29 may be located within the GTTR, as shown in Fig. 1. Pulling rolls may also be located below the GTTR, if desired. The temperature of the edge rollers may be below that of the glass. In embodiments, the edge rollers may be water or air cooled. As a result of this lower temperature, the edge rollers may locally reduce the glass' temperature. This cooling may reduce the thinning of the ribbon. Pulling rolls 29 may also generally be cooler than the glass they contact, but because they may be located further down the draw, the difference in temperature may be less than at the edge rollers 27. [0021] FIG. 2 shows a continuous glass ribbon 15 according to embodiments. As shown in FIG. 2, 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_center, where t_center is the final thickness of the ribbon along the centerline. A thickness of 1.05*t_center, 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). Although 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.

[0022] In embodiments, 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. In embodiments, 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.

[0023] Referring now to FIG. 3, one embodiment of a vertical bead scoring machine (VBS) 300 with a flattening apparatus 310 and a scoring apparatus 320 is schematically depicted from the side. The VBS 300 with flattening apparatus 310 and scoring apparatus 320 may be used in conjunction with one or more embodiments of the methods for separating a bead portion of a glass sheet shown and described herein. In the embodiment depicted in FIG. 3, the VBS 300 also comprises a scoring bar linkage 330 that links the flattening apparatus 310 and the scoring apparatus 320. The VBS may also comprise a nosing 345 positioned to create a glass conveyance pathway and support a glass sheet during scoring. For example, 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. When a glass sheet is present in the glass conveyance pathway, 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. In embodiments, the glass conveyance pathway 346 may be vertically oriented. However, it should be understood that, in alternative embodiments, 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.

[0024] Still referring to FIG. 3, 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. However, it should be understood that other configurations of the flattening apparatus are possible.

[0025] The support frame 311 may be formed from any suitable rigid or semi-rigid material. In embodiments, the support frame 31 1 may be made of metal, such as steel or aluminum. In other embodiments, 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. As shown in the embodiment depicted in FIG. 3, 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. However, it is understood that 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.

[0026] 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. However, in embodiments, 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. [0027] In the embodiment shown in FIG. 4, 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. In one embodiment, the actuator 313 is an Airpel low friction cylinder with a 1 inch stroke length and a 16 mm bore manufactured by Airpot Corporation. However, it should be understood that other, similar low friction cylinders may also be used to actively flatten the glass sheet. 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. In embodiments, 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. As shown in FIG. 4, the slide mechanism 414 may be slideably attached to the support frame 311 and may be connected to the flattening wheel 312. In embodiments, the slide mechanism 414 moves in a lateral direction (i.e., +/- x-direction of FIG. 3) when the actuator 313 is extended or retracted, thereby moving the flattening wheel 312 into position relative to the glass conveyance pathway 346 (shown in FIG. 3). For example, 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. When the slide mechanism moves in the lateral direction it may be supported and/or guided by the convex portion of the support frame.

[0028] Referring again to FIG. 3, the flattening wheel 312 may be moved in a direction towards the nosing 345 (i.e., in the positive x-direction on the coordinate axes depicted in FIG. 3) by extending the shaft 430 of the actuator 313 in the positive x-direction. The flattening wheel 312 may likewise be moved in the negative x-direction by moving the actuator 313 in the negative x-direction.

[0029] As shown in FIG. 3, 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. However, 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.

[0030] In the embodiment shown in FIG. 3, the scoring apparatus 320 comprises a mechanical scoring device, such as a scoring wheel or scoring point. Alternatively, 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 scoring apparatus 320 may be positioned in the x-direction such that the scoring apparatus, specifically the scoring wheel 323, is directly opposite the nosing 345 and positioned in the glass conveyance pathway 346, as depicted in FIG. 3. Accordingly, it should be understood that the scoring apparatus 320 may be utilized to score the glass sheet 340 as the glass sheet is supported on the nosing 345 thereby introducing a scoring line in the surface of the glass sheet opposite the nosing.

[0031] 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. In embodiments, 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. However, it should be understood that flattening wheels with other Shore A hardnesses may also be used. In general, the hardness of the wheel may be changed based on the thickness of the glass sheet. [0032] As shown in the embodiments of FIGS. 6A - 6C, the flattening wheel may comprise one or more o-rings 610. The number of o-rings included on the flattening wheel 312 is not particularly limited and, in embodiments, the flattening wheel may comprise one o-ring 610, as shown in FIG. 6A, two o-rings 610, as shown in FIG. 6B, or three o-rings 610, as shown in FIG. 6C. 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. For example, 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.

[0033] The 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. However, it should be understood that other embodiments of VBSs may also be used. For example, VBSs having two flattening wheels, as shown in FIG. 5 may be used.

[0034] As shown in FIG. 5, the flattening apparatus may include a trailing flattening wheel 510. The trailing flattening wheel may be positioned linearly to the scoring wheel 323 and the flattening wheel 312. A support beam 511 may connect the trailing flattening wheel 510 and the flattening wheel 312. The distance between the trailing flattening wheel 510 and the flattening wheel 312 may be greater than or equal to about 10 mm. For example, in some embodiments, the distance between the trailing flattening wheel 510 and the flattening wheel 312 may be greater than or equal to about 10 mm and less than or equal to 100 mm. The spacing between the trailing flattening wheel 510 and the flattening wheel 312 is adjustable based on the thickness of the glass sheet being operated on. The trailing flattening wheel 510 may move in unison with the flattening wheel 312 in both the x-direction and the y-direction. The trailing flattening wheel 510 is positioned on an opposite side of the scoring apparatus 320 than the flattening apparatus 310. Thus, the trailing flattening wheel 510 maintains the flatness of the glass sheet 340 after the glass sheet has been scored. The configuration of the trailing flattening wheel may be changed to prevent surface tension on the score line before a bending moment is applied to separate the bead from the glass sheet which is discussed further below. For example, trailing flattening wheels may be positioned on both, or a single side of the scoreline to create local tension on the median crack which develops due to scoring. However, it should be understood that other roller options are possible. For example, in the case of very thin glass, compressive stress may be created on the glass surface using the flattening and trailing flattening wheels to arrest or stall uncontrolled crack propagation. In either case the tension or compression imparted to the glass surface are controlled by the flattening wheel, as well as the interaction between the flattening wheels and the trailing flattening wheels with the back-up nosing material geometry and durometer.

[0035] The bending moment that separates the glass bead from the glass sheet may be applied by any suitable mechanism. In embodiments, clamp bars (not shown) may be installed as part of the VBS. Referring back to FIG. 2, the clamp bars may be positioned to contact the glass sheet at some point on the glass bead, for example between 19a, 19b and 25a, 25b respectively, without contacting the thin, central portion of the glass sheet. The clamp bars may cover the entire length of the glass sheet, or any portion thereof. Once the clamp bars are positioned on the glass sheets, they may be moved to provide a bending moment that separates the glass bead from the glass sheet. In some embodiments, the clamp bars may be used with thin glass sheet, such as, for example 0.3t glass sheets. 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. When clamp bars are used with highly warped glass sheets, pockets of non-uniformity (i.e., warp or distortion) may remain causing localized scoring issues in the area of the non-uniformity which can lead to breakage. The use of the flattening rollers counteracts this problem.

[0036] Referring now to FIG. 7, one embodiment of an exemplary glass manufacturing system 700 is schematically depicted. The glass manufacturing system utilizes a VBS 300 as shown in FIG. 3. The glass manufacturing system 700 includes a melting vessel 710, a fining vessel 715, a mixing vessel 720, a delivery vessel 725, a fusion draw machine (FDM) 741 , sheet separation apparatus 761 , and VBS 300. Glass batch materials are introduced into the melting vessel 710 as indicated by arrow 712. The batch materials are melted to form molten glass 726. The fining vessel 715 has a high temperature processing area that receives the molten glass 726 from the melting vessel 710 and in which bubbles are removed from the molten glass 726. The fining vessel 715 is fluidly coupled to the mixing vessel 720 by a connecting tube 722. The mixing vessel 720 is, in turn, fluidly coupled to the delivery vessel 725 by a connecting tube 727.

[0037] The delivery vessel 725 supplies the molten glass 726 through a downcomer 730 into the FDM 741. The FDM 741 comprises an inlet 732, a forming vessel 735, and a pull roll assembly 740. As shown in FIG. 7, the molten glass 726 from the downcomer 730 flows into an inlet 732 that leads to the forming vessel 735. The forming vessel 735 includes an opening 736 that receives the molten glass 726 that flows into a trough 737 and then overflows and runs down two sides 738a and 738£ before fusing together at a root 739. The root 739 is where the two sides 738a and 738£ come together and where the two overflow walls of molten glass 726 rejoin (e.g., re-fuse) before being drawn downward by the pull roll assembly 740 to form the continuous glass ribbon 15.

[0038] As the continuous glass ribbon 15 exits the pull roll assembly 740, the molten glass solidifies. Due to the differences in the thickness of the molten glass at the edges and center of the continuous glass ribbon 15, the center of the continuous glass ribbon cools and solidifies more quickly than the edges of the continuous glass ribbon creating a temperature gradient from the edges to the center of the continuous glass ribbon 15. As the molten glass cools, the temperature gradient causes stresses to develop in the glass which, in turn, causes the glass to bow or curve in a lateral direction (i.e., in the direction from one edge of the glass to the other). Accordingly, it should be understood that the continuous glass ribbon 15 has a radius of curvature in a lateral direction.

[0039] Referring now to the glass manufacturing system 700 schematically depicted in FIG. 7, 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. [0040] The carriage then transfers the glass sheet to the VBS to remove the glass bead from the glass sheet. In embodiments, 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.

[0041] The glass sheet 340 may be pulled through the VBS 300 by any acceptable mechanism, such as, for example, pulling rollers (not shown) or a top-clamp conveyor (not shown). Once in the VBS 300, a surface of the glass sheet 340 facing away from the scoring apparatus 320 and the flattening apparatus 310 (i.e., the b-surface) may be supported by the nosing 345. As shown in FIG. 3, the flattening wheel 312 may initially be positioned at or near the top of the glass sheet 340 in the y-direction. The low- friction air cylinder 313 and the low-friction slide mechanism 314 may be retracted so that the flattening wheel 312 does not initially contact the glass sheet. The scoring apparatus 320 may be located above the top of the glass sheet 340 in the y-direction, as shown in FIG. 3. After the glass sheet is positioned in the VBS 300, the shaft of the flattening apparatus is extended, thereby causing the slide mechanism 314 to move in the positive x-direction. For example, in embodiments where 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). In embodiments, 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. In some embodiments, the pressure applied to the glass sheet 340 by the flattening wheel 312 may be about 20 psi.

[0042] After the low-friction air cylinder 313 has been extended, and the flattening wheel is moveably engaged with the glass sheet, 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. As mentioned above, in embodiments, 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. Flattening of the glass sheet occurs before scoring touchdown and remains active throughout scoring until the scoring wheel 323 is removed from the glass sheet, thereby providing a flattened area of the glass sheet throughout the scoring operation. Allowing the flattening wheel 312 to contact the glass sheet in advance of the scoring wheel 323 may flattens any curvature in the glass sheet at or near the glass bead, which allows the scoring wheel to maintain a uniform vent in the glass sheet. Although not limited thereto, a vent may be defined as an indentation line formed in the sheet surface that opens that surface to a certain depth. In embodiments, 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. In embodiments, the vent may extend in a vertical direction from one end of the glass sheet to the other end of the glass sheet.

[0043] After the flattening wheel 312 and the scoring wheel 323 have traversed the entirety of the height of the glass sheet (i.e., reached the bottom of the glass sheet in the y-direction), 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. Similarly, 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.

[0044] The VBS 300 may be moved in the y-direction by any suitable mechanism. In embodiments, 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. Alternatively, the VBS 300 may be positioned with a robotic device, such as a robotic arm. It should be recognized that, in embodiments, 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.

[0045] 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. Although 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.

[0046] 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.

Claims

CLAIMS What is claimed is:

1. A glass sheet scoring machine comprising:

a scoring apparatus for scoring a glass sheet;

a flattening apparatus comprising a flattening device;

a scoring bar linkage connecting the scoring apparatus and the flattening apparatus; and

a support nosing, wherein the support nosing is positioned opposite and spaced apart from the scoring apparatus and the flattening apparatus by a glass conveyance pathway through the glass sheet scoring machine.

2. The glass sheet scoring machine of claim 1, wherein the flattening device and the scoring apparatus are positioned linearly in a vertical direction.

3. The glass sheet scoring machine of claim 1, wherein a distance between the flattening device and the scoring apparatus is greater than or equal to about 10 mm.

4. The glass sheet scoring machine of claim 1, wherein: the flattening apparatus comprises an actuator that is moveably coupled to the flattening device;

the flattening device is not present in the glass conveyance pathway when the actuator is in a retracted position, and

the flattening device is present in the glass conveyance pathway when the actuator is in an extended position.

5. The glass sheet scoring machine of claim 4, wherein the actuator is a low- friction air cylinder.

6. The glass sheet scoring machine of claim 5, wherein the low-friction air cylinder comprises a stroke and the low-friction air cylinder is at about the middle of the stroke when in the extended position.

7. The glass sheet scoring machine of claim 4, wherein the actuator is moveably coupled to the flattening device via a slide mechanism.

8. The glass sheet scoring machine of claim 1, wherein the flattening device is a flattening wheel.

9. The glass sheet scoring machine of claim 8, wherein the glass conveyance pathway is oriented in a vertical direction, and an axis of rotation of the flattening wheel is oriented in a horizontal direction.

10. The glass sheet scoring machine of claim 8, wherein the flattening wheel has a diameter from about 0.5 inches to about 1.5 inches.

11. The glass sheet scoring machine of claim 8, wherein the flattening wheel has a width of from about 0.25 inches to about 1.00 inches.

12. The glass sheet scoring machine of claim 8, wherein the flattening wheel comprises from one to three o-rings positioned on its circumference.

13. The glass sheet scoring machine of claim 12, wherein at least one o-ring has a rounded shape.

14. The glass sheet scoring machine of claim 12, wherein at least one o-ring has a square shape.

15. The glass sheet scoring machine of claim 1, further comprising a trailing flattening device, wherein the trailing flattening device is positioned on an opposite side of the scoring apparatus from the flattening device.

16. The glass sheet scoring machine of claim 15, wherein a distance between the trailing flattening device and the flattening device is greater than or equal to about 10 mm.

17. A method for removing beads from a glass sheet:

positioning the glass sheet in a flattening apparatus comprising a flattening device and a scoring apparatus at or near one end of the glass sheet when the glass sheet in positioned in the scoring apparatus;

extending the flattening device toward the glass sheet so that the flattening device is in moveable contact with the glass sheet and the glass sheet is impinged between the flattening device and a support nosing;

flattening a portion of the glass sheet by moving the flattening apparatus along a length of the glass sheet to an opposite end of the glass sheet;

scoring the portion of the glass sheet by moving the scoring apparatus along a length of the glass sheet to the opposite end of the glass sheet;

wherein the flattening device flattens the portion of the glass sheet before the portion of the glass sheet is scored.

18. The method of claim 17 further comprising:

retracting the flattening device so that it is no longer in contact with the glass sheet; and

repositioning the flattening apparatus and the scoring apparatus at or near the one end of the glass sheet.

19. The method of claim 17, wherein the flattening apparatus is extended by actuating a low-friction air cylinder that moves the flattening device toward a surface of the glass sheet.

20. The method of claim 17, wherein the extending, flattening, scoring, retracting, and repositioning steps are controlled by timing sequence logic.

21. The method of claim 17, wherein a pressure of from about 10 psi to about 30 psi is applied to the glass sheet by the flattening device when the flattening device is extended.

22. The method of claim 17, wherein a temperature of the glass sheet is from about room temperature to about 450°C.

23. The method of claim 17, wherein the glass sheet has a thickness of 1.00 mm or less.

24. The method of claim 17, wherein the flattening apparatus and the scoring apparatus are operationally connected by a scoring bar linkage that extends from the flattening apparatus to the scoring apparatus.