WO2017161104A1

WO2017161104A1 - Methods and apparatus for supporting glass

Info

Publication number: WO2017161104A1
Application number: PCT/US2017/022679
Authority: WO
Inventors: Donald Orrin Bigelow; Chester Hann Huei Chang; Kevin A. Cole; Brian Paul DAUGHERTY; Sean Matthew Garner
Original assignee: Corning Incorporated
Priority date: 2016-03-17
Filing date: 2017-03-16
Publication date: 2017-09-21
Also published as: TW201736295A

Abstract

An airbar to provide a cushion of air to support a glass ribbon can include an arcuate surface including an axis of curvature, and a plurality of apertures arranged on a circumferential portion of the arcuate surface. The circumferential portion of the arcuate surface can include a first region and a second region. A first density of the plurality of apertures of the first region can be greater than a second density of the plurality of apertures of the second region. Methods of testing a strength of a glass ribbon with the airbar, a leveling arm including the airbar, and a vacuum box including the airbar are also provided.

Description

METHODS AND APPARATUS FOR SUPPORTING GLASS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U. S.C. § 119 of U. S. Provisional Application Serial No. 62/309631 filed on March 17, 2016, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates generally to methods and apparatus for supporting glass and, more particularly, to methods and apparatus for supporting a glass ribbon with a cushion of air.

BACKGROUND

[0003] Glass sheets are commonly used, for example, in display applications, including liquid crystal displays (LCDs), electrophoretic displays (EPDs), light emitting diode (LED) displays, organic light emitting diode (OLED) displays, plasma display panels (PDPs), touch sensors, photovoltaics, color-filter, thin film transistor (TFT) backplanes, or other optical, electronic, or display applications. Glass sheets are commonly fabricated by, for example, flowing molten glass to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming processes including slot draw, float, down-draw, fusion down- draw, up-draw, press rolling, or other glass forming processes and techniques. The glass ribbon may then be subsequently divided or cut to provide one or more glass sheets suitable for further processing into desired display applications.

[0004] Airbars are intended to provide a cushion of air to support a glass ribbon without contacting the glass ribbon (e.g., without contacting the glass ribbon with a solid object). Unlike solid objects (e.g., rollers) that may scratch, chip, and otherwise damage a pristine surface of the glass ribbon, a cushion of air can impinge on a pristine surface of the glass ribbon, and therefore impart a force on the glass ribbon, without scratching, chipping, or otherwise damaging the pristine surface of the glass ribbon. In some applications, the glass ribbon can be supported by a cushion of air and conveyed over an airbar. In other applications, the airbar may be used to impart a bend in the glass ribbon. Some existing airbars may be unable to maintain a non-contact relationship with the glass ribbon, for example, during conveyance of the glass ribbon over the airbar, when imparting a bend in the glass ribbon with the airbar, and other instances when the airbar is employed to provide a cushion of air to support the glass ribbon. Thus, in some existing applications, the glass ribbon may unintentionally come into contact with the airbar in which case, the glass ribbon can be subjected to possible scratches, chips, and other damage.

[0005] Accordingly, an airbar that can provide a cushion of air to support a glass ribbon in various configurations of the glass ribbon and without contacting the glass ribbon is desirable.

SUMMARY

[0006] There are set forth methods and apparatus to provide a cushion of air to support a glass ribbon. In particular, some methods and apparatus can support a glass ribbon conveyed in a curved path including, for example, when inserting a curved airbar into an otherwise straight path to impart a bend in a glass ribbon. The methods and apparatus can also determine a strength of a glass ribbon using non-contact techniques.

[0007] In some embodiments, an airbar to provide a cushion of air to support a glass ribbon can include an arcuate surface including an axis of curvature, and a plurality of apertures arranged on a circumferential portion of the arcuate surface. A first region of the circumferential portion of the arcuate surface can be oriented to provide the cushion of air to support the glass ribbon in a planar configuration. The first region of the circumferential portion of the arcuate surface and a second region of the circumferential portion of the arcuate surface can be oriented to provide the cushion of air to support the glass ribbon in a non-planar configuration. A first density of the plurality of apertures of the first region can be greater than a second density of the plurality of apertures of the second region.

[0008] In some embodiments, the first density of the plurality of apertures of the first region can be from about two times to about four times greater than the second density of the plurality of apertures of the second region.

[0009] In some embodiments, the first density of the plurality of apertures of the first region can be about three times greater than the second density of the plurality of apertures of the second region.

[0010] In some embodiments, the first region can include a first axis parallel to the axis of curvature of the arcuate surface at a first radius of curvature of the arcuate surface, the second region can include a second axis parallel to the axis of curvature of the arcuate surface at a second radius of curvature of the arcuate surface, and a first central angle between the first radius of curvature and the second radius of curvature can be about 45 degrees. The first radius of curvature can be oriented to be perpendicular to a major surface of the glass ribbon when the first region of the circumferential portion of the arcuate surface is oriented to provide the cushion of air to support the glass ribbon in the planar configuration. [0011] In some embodiments, the circumferential portion of the arcuate surface can be defined between a third axis parallel to the axis of curvature of the arcuate surface at a third radius of curvature of the arcuate surface and a fourth axis parallel to the axis of curvature of the arcuate surface at a fourth radius of curvature of the arcuate surface. A first angle between the first radius of curvature and the third radius of curvature can be about 5 degrees, a second angle between the second radius of curvature and the fourth radius of curvature can be about 5 degrees, and a second central angle between the third radius of curvature and the fourth radius of curvature can be about 55 degrees.

[0012] In some embodiments, the first region can be defined between the third axis and a fifth axis parallel to the axis of curvature of the arcuate surface at a fifth radius of curvature of the arcuate surface. A third angle between the first radius of curvature and the fifth radius of curvature can be about 10 degrees, and a third central angle between the third radius of curvature and the fifth radius of curvature can be about 15 degrees.

[0013] In some embodiments, the second region can be defined between the fourth axis and the fifth axis.

[0014] In some embodiments, the first region can be defined between the third axis and a sixth axis parallel to the axis of curvature of the arcuate surface at a sixth radius of curvature of the arcuate surface. A fourth angle between the first radius of curvature and the sixth radius of curvature can be about 20 degrees, and a fourth central angle between the third radius of curvature and the sixth radius of curvature can be about 25 degrees.

[0015] In some embodiments, the second region can be defined between the fourth axis and the sixth axis.

[0016] In some embodiments, a method of testing a strength of a glass ribbon can include traversing the glass ribbon over the airbar.

[0017] In some embodiments, the method can further include imparting a plurality of bends in the glass ribbon while traversing the glass ribbon over the airbar. The plurality of bends can produce a corresponding plurality of tensile stresses in the glass ribbon. The method can include determining a strength of the glass ribbon based at least in part on the corresponding plurality of tensile stresses.

[0018] In some embodiments, the method can further include incrementally increasing at least one of the corresponding plurality of tensile stresses and determining a strength of the glass ribbon based at least in part on the increased at least one of the corresponding plurality of tensile stresses. [0019] In some embodiments, the method can further include incrementally increasing at least one of the corresponding plurality of tensile stresses until the glass ribbon fails.

[0020] In some embodiments, the method can further include unwinding the glass ribbon from a first spool, then traversing the glass ribbon over the airbar, and then rewinding the glass ribbon onto a second spool.

[0021] In some embodiments, a leveling arm to maintain a tension in a glass ribbon can include the airbar attached to a first end of the leveling arm. The airbar can be oriented to provide a cushion of air to support the glass ribbon. A counter-balance can be attached to a second end of the leveling arm, and the leveling arm can include a pivot location between the first end and the second end about which the first end and the second end can be oriented to rotate.

[0022] In some embodiments, a weight of the counter-balance can be based at least in part on a force of the glass ribbon acting on the airbar.

[0023] In some embodiments, a vacuum box to impart a bend in a glass ribbon can include an enclosure including two opposing sides and an opening between the two opposing sides. The opening can be oriented to define a plane through which the glass ribbon can cross from outside the enclosure to inside the enclosure. A vacuum port can be oriented to provide a negative pressure within the enclosure. At least one airbar can be arranged at the opening of the enclosure adjacent to at least one of the two opposing sides. The at least one airbar can be oriented to provide a cushion of air to support the glass ribbon.

[0024] In some embodiments, the two opposing sides can be tapered relative to each other to narrow in a direction away from the opening.

[0025] In some embodiments, the vacuum box can further include a vacuum source to provide the negative pressure to the vacuum port.

[0026] The above embodiments may be used in any and all combinations with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other features, embodiments, and advantages are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0028] FIG. 1 is a top view of an exemplary airbar oriented to support a glass ribbon in accordance with embodiments disclosed herein;

[0029] FIG. 2 is a view of the exemplary airbar along line 2-2 of FIG. 1; [0030] FIG. 3 is a cross-sectional view of the exemplary airbar along line 3-3 of FIG. 1, where the airbar is oriented to support a glass ribbon in a planar configuration;

[0031] FIG. 4 is another cross-sectional view of the exemplary airbar along line 4-4 of FIG. 1, where the airbar is oriented to support a glass ribbon in a non-planar configuration;

[0032] FIG. 5 is a cross-sectional perspective view of an exemplary airbar in accordance with embodiments disclosed herein;

[0033] FIG. 6 is a side view of an exemplary apparatus for testing strength of a glass ribbon in accordance with embodiments disclosed herein.

[0034] FIG. 7 is another side view of the exemplary apparatus for testing strength of a glass ribbon in accordance with embodiments disclosed herein;

[0035] FIG. 8 is a partial front view of an exemplary airbar including an enlarged view of a plurality of apertures in accordance with embodiments disclosed herein;

[0036] FIG. 9 is side view of an exemplary vacuum box in accordance with embodiments disclosed herein;

[0037] FIG. 10 is top view of an exemplary leveling arm in accordance with embodiments disclosed herein; and

[0038] FIG. 11 is a side view of the exemplary leveling arm along line 11-11 of FIG.

10

DETAILED DESCRIPTION

[0039] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, claims may encompass many different features of various embodiments and should not be construed as limited to the embodiments set forth herein. Directional terms as used herein (e.g., up, down, right left, front, back, top, bottom) are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0040] Glass is commonly fabricated by flowing molten glass to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming processes including, float, slot draw, down-draw, fusion down-draw, up-draw, or any other forming processes. The glass ribbon from any of these processes may then be subsequently divided to provide glass sheets suitable for further processing into a desired application, e.g., a display application. For example, the glass sheets can be used in a wide range of display applications, including liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), or the like. [0041] It is to be understood that specific embodiments disclosed herein are intended to be exemplary and therefore non-limiting. The present disclosure relates to methods and apparatus for supporting a glass ribbon. In some embodiments, the glass ribbon to be supported can include a glass ribbon formed from a glass manufacturing apparatus. In some embodiments, the glass ribbon can be provided as it is being formed from a glass manufacturing apparatus, can be provided from a spool of previously-formed glass ribbon that can be uncoiled from the spool, or can be provided as a freestanding glass ribbon. In other embodiments, the glass ribbon can include a glass sheet formed by a glass manufacturing apparatus. In some embodiments, the glass sheet can be provided as a freestanding glass sheet, a glass sheet separated from a glass ribbon, a glass sheet separated from another glass sheet, a glass sheet uncoiled from a spool of glass sheets, or a glass sheet from a stack of glass sheets. In some embodiments, the glass ribbon can include an edge portion (e.g., a glass ribbon edge portion, an edge portion including a thickened edge bead, etc.). In other embodiments, the glass ribbon can include an edge from which an edge portion may have been previously separated.

[0042] Methods and apparatus for supporting a glass ribbon will now be described by way of exemplary embodiments for supporting a glass ribbon with the understanding that similar or identical techniques may also be applied to support any glass ribbon, including the exemplary glass ribbons discussed above as well as glass ribbons not explicitly disclosed herein.

[0043] Referring to FIG. 1 and FIG. 2, an airbar 100 to provide a cushion of air 125 to support a glass ribbon 120 can include an arcuate surface 105 including an axis of curvature 102 (e.g., parallel to a width 101 of the airbar 100). A plurality of apertures 110 (schematically illustrated in FIG. 5 and FIG. 8) can be arranged on a circumferential portion 115 of the arcuate surface 105 along a width 116 of the circumferential portion 115. A first region 130 of the circumferential portion 115 of the arcuate surface 105 can be oriented to provide the cushion of air 125 to support the glass ribbon 120 in a planar configuration 150 (e.g., as shown in FIG. 3). In addition, the first region 130 and a second region 140 of the circumferential portion 115 of the arcuate surface 105 can be oriented to provide the cushion of air 125 to support the glass ribbon 120 in a non-planar configuration 160 (e.g., as shown in FIG. 4). The airbar 100 can provide the cushion of air 125 to support the glass ribbon 120 without contacting the glass ribbon 120 (e.g., without contacting the glass ribbon 120 with a solid object). [0044] For example, the first region 130 can be oriented to provide the cushion of air 125 to support the glass ribbon 120 in a planar configuration 150 without contacting the glass ribbon 120 with a solid object. Likewise, the first region 130 and the second region 140 can be oriented to provide the cushion of air 125 to support the glass ribbon 120 in a non-planar configuration 160 without contacting the glass ribbon 120 with a solid object. In the non- planar configuration 160, the airbar 100 can be oriented to support the glass ribbon 120 where the glass ribbon 120 wraps around at least a portion of the airbar 100, for example, in the illustrated counter-clockwise direction relative to the axis of curvature 102 shown in FIG. 2, or the illustrated clockwise direction relative to the axis of curvature 102 shown in FIG. 4. In other embodiments, the glass ribbon 120 can be supported by the cushion of air 125 over any wrap angle in at least one of a clockwise direction and a counter-clockwise direction relative to the axis of curvature 102 of the arcuate surface 105.

[0045] In some embodiments, the airbar 100 can include a hollow structure with the plurality of apertures 110 formed in a wall of the hollow structure (e.g., drilled through a wall of the hollow tube). For example, in some embodiments, a plurality of circular apertures can be formed in the hollow structure using one or more circular drill bits having a prescribed diameter. In other embodiments, any one or more of the plurality of apertures 110 can include a combination of any one or more shapes, including circular apertures, slotted apertures, and polygonal apertures. The plurality of apertures 110 can be positioned in a plurality of rows along the width 116 of the circumferential portion 115 of the arcuate surface 105. In some embodiments, the plurality of apertures 110 can be uniformly spaced along the width 116 of the circumferential portion 115 of the arcuate surface 105. In other embodiments, adjacent rows of the plurality of apertures 110 can be staggered relative to each other along the width 116 of the circumferential portion 115 of the arcuate surface 105 to accommodate, for example, an increased number of apertures in a given area. Unless otherwise noted, any number, pattern, distribution, and alignment, of the plurality of apertures 110 can be provided.

[0046] Furthermore, although schematically illustrated herein as a hollow cylinder having a circular cross-section (e.g., as shown in FIGS. 3 and 4), the airbar 100 can include structure having any shape or combination of shapes. For example, the hollow structure can include a cross-section of any shape, including a combination of any one or more of a circular cross-section, an elliptical cross-section, and a polygonal cross-section, where at least a portion of the cross-section includes the arcuate surface 105. The arcuate surface 105 can include any radius of curvature 106 relative to the axis of curvature 102 including a radius of curvature 106 that is constant over a portion of the arcuate surface 105 or that is constant over the entire arcuate surface 105 as well as a radius of curvature 106 that varies over a portion of the arcuate surface 105 or that varies over the entire arcuate surface 105. In still other embodiments, a radius of curvature 106 of the arcuate surface 105 can be from about 1.25 inches to about 3 inches, although other dimensions can be provided in further embodiments and are considered to be within the scope of the disclosure.

[0047] The glass ribbon 120 can include a width 121 and a thickness 124 defined between a first major surface 122 and a second major surface 123 thereof. The glass ribbon 120 can include any one or more of a variety of compositions including but not limited to soda-lime glass, borosilicate glass, alumino-borosilicate glass, an alkali-containing glass, or an alkali-free glass. In some embodiments, the glass ribbon 120 can further include one or more layers of lamination applied to at least one of the first major surface 122 of the glass ribbon 120 and the second major surface 123 of the glass ribbon 120. As shown in FIG. 1, the width 101 of the airbar 100 can be greater than the width 121 of the glass ribbon 120. Likewise, the width 116 of the circumferential portion 115 including the plurality of apertures 110 can also be greater than the width 121 of the glass ribbon 120. Accordingly, in some embodiments, the airbar 100 can support a glass ribbon 120 of varying widths and can also take into account possible misalignment or transverse motion of the glass ribbon 120 relative to the airbar 100, for example, when the glass ribbon 120 is being traversed over the airbar 100

[0048] In some embodiments, the thickness 124 of the glass ribbon 120 can be from about 50 microns to about 700 microns, for example from about 100 microns to about 700 microns, for example from about 200 microns to about 700 microns, for example from about 300 microns to about 700 microns, for example from about 400 microns to about 700 microns, for example from about 500 microns to about 700 microns, for example from about 600 microns to about 700 microns, for example from about 50 microns to about 100 microns, for example from about 50 microns to about 200 microns, for example from about 50 microns to about 300 microns, for example from about 50 microns to about 400 microns, for example from about 50 microns to about 500 microns, and for example from about 50 microns to about 600 microns. It is to be understood, however, that the methods and apparatus disclosed herein can be employed to support any glass having any thickness 124, including any of the above listed thicknesses, as well as ranges, and subranges, of the above listed thickness, and also thicknesses, ranges, and subranges not explicitly disclosed herein. [0049] In some embodiments, the width 121 of the glass ribbon 120 can be from about 20 mm to about 4000 mm, for example from about 50 mm to about 4000 mm, for example from about 100 mm to about 4000 mm, for example from about 500 mm to about 4000 mm, for example from about 1000 mm to about 4000 mm, for example from about 2000 mm to about 4000 mm, for example from about 3000 mm to about 4000 mm, for example from about 20 mm to about 50 mm, for example from about 20 mm to about 100 mm, for example from about 20 mm to about 500 mm, for example from about 20 mm to about 1000 mm, for example from about 20 mm to about 2000 mm, and for example from about 20 mm to about 3000 mm. It is to be understood, however, that the methods and apparatus disclosed herein can be employed to support any glass having any width 121, including any of the above listed widths, as well as ranges, and subranges, of the above listed widths, and also widths, ranges, and subranges not explicitly disclosed herein.

[0050] In addition, pressurized air can be provided to an interior 107 (e.g., as shown in FIGS. 2, 3, 4, and 5) of the airbar 100 (e.g., from a pressurized air source, not shown) and can pass from the interior 107 of the airbar 100 to an exterior 108 of the airbar 100 through the plurality of apertures 110 to provide the cushion of air 125. In some embodiments, a pressure of the pressurized air can be adjusted to control, for example, a corresponding pressure of the cushion of air 125. In further embodiments, a negative pressure can be provided at one or more of the plurality of apertures 110 to control the pressure of the cushion of air 125. For example, a negative pressure at one or more of the plurality of apertures 110 can pull the glass ribbon 120 towards the airbar 100 in a corresponding localized region, whereas a positive pressure at one or more of the plurality of apertures 110 can lift the glass ribbon 120 away from the airbar 100 in another corresponding localized region. It is to be understood that any pressure of the cushion of air 125 (e.g., 5 inches of water, 10 inches of water, 15 inches of water, 20 inches of water, 40 inches of water, 5-40 inches of water, etc.) can be provided in further embodiments without departing from the scope of the disclosure.

[0051] In some embodiments, the airbar 100 can provide a combination of positive pressure and negative pressure to create a cushion of air 125 that provides greater stability to, for example, support the glass ribbon 120 relative to the airbar 100 at a predetermined distance over the entire supported region of the glass ribbon 120 and to maintain the predetermined distance over a period of time. Furthermore, a combination of positive pressure and negative pressure can create a cushion of air 125 that respectively lifts and pulls the glass ribbon 120 relative to the airbar 100 at selected locations to stabilize the glass ribbon 120 when transitioning between, and when in, various states of disengagement and engagement of the glass ribbon 120 relative to the airbar 100. Moreover, it is to be understood that the cushion of air 125 can include any gas or combination of gases, including noble gases, filtered gases, and any other gas. Accordingly, unless otherwise noted, the term "air," as used herein, is intended to encompass all suitable types of gas and is therefore not intended to limit the scope of the disclosure.

[0052] The cushion of air 125 can support the glass ribbon 120 by producing a pressurized zone that can support (e.g., at least one of lift and pull) the glass ribbon 120 relative to the airbar 100. Therefore, when the glass ribbon 120 includes a non-planar configuration 160 (e.g., as shown in FIG. 2 and FIG. 4) and is wrapped around at least a portion of the airbar 100, the cushion of air 125 can be provided, and the pressurized zone can be contained under the glass ribbon 120 based at least in part on the wrap angle of the glass ribbon 120 around at least a portion of the airbar 100. Conversely, when the glass ribbon 120 includes a planar configuration 150 (e.g., as shown in FIG. 2 and FIG. 3), the pressurized zone can be bounded by the planar surface of the glass ribbon 120 and can therefore escape to the atmosphere more easily than when the glass ribbon 120 is wrapped around at least a portion of the airbar 100. Thus, a relatively higher pressure of air may be employed to support the glass ribbon 120 relative to the airbar 100 when the glass ribbon 120 is in the planar configuration 150 (and the first region 130 is oriented to support the glass ribbon 120) as compared to a pressure of air employed to support the glass ribbon 120 relative to the airbar 100 when the glass ribbon 120 is in the non-planar configuration 160 (and the first region 130 and the second region 140 are oriented to support the glass ribbon 120). Thus, the first region 130 of the airbar 100 can support the glass ribbon 120 in a planar configuration 150 (e.g., as shown in FIG. 3) and the first region 130 and the second region 140 of the airbar 100 can support the glass ribbon 120 in a non-planar configuration 160 (e.g., see FIG. 4) ensuring in both the planar configuration 150 and the non-planar configuration 160 that the glass ribbon 120 is supported by the cushion of air 125 and does not come into contact with solid structure (e.g., arcuate surface 105) the airbar 100.

[0053] As schematically illustrated in FIG. 5, the first region 130 of the circumferential portion 115 of the arcuate surface 105 can include a first axis 171 parallel to the axis of curvature 102 of the arcuate surface 105 at a first radius of curvature 181 of the arcuate surface 105. Similarly, the second region 140 of the circumferential portion 115 of the arcuate surface 105 can include a second axis 172 parallel to the axis of curvature 102 of the arcuate surface 105 at a second radius of curvature 182 of the arcuate surface 105. A first central angle 191 between the first radius of curvature 181 and the second radius of curvature 182 can be about 45 degrees. The first radius of curvature 181 can be oriented to be perpendicular to a major surface (e.g., first major surface 122, second major surface 123) of the glass ribbon 120 when the first region 130 of the circumferential portion 115 of the arcuate surface 105 is oriented to provide the cushion of air 125 to support the glass ribbon 120 in the planar configuration 150. Thus, as shown in FIG. 3, when the glass ribbon 120 is in a planar configuration 150, a first plane 155 parallel to a major surface (e.g., first major surface 122, second major surface 123) of the glass ribbon 120 can be tangent to the arcuate surface 105 along the first axis 171 of the first region 130. In addition, as shown in FIG. 4, when the glass ribbon 120 is in a non-planar configuration 160, the first plane 155 parallel to the major surface (e.g., first major surface 122, second major surface 123) of the glass ribbon 120 can be tangent to the arcuate surface 105 along the first axis 171 of the first region 130 and a second plane 165 parallel to a major surface (e.g., first major surface 122, second major surface 123) of the glass ribbon 120 can be tangent to the arcuate surface 105 along the second axis 172 of the second region 140.

[0054] Based on experimental testing, it was determined, in some embodiments, that a uniform distribution (e.g., uniform density of apertures) on the airbar 100 was not capable of maintaining adequate clearance between the glass ribbon 120 and the airbar 100. For example, it was determined that, in some embodiments, the glass ribbon 120 and the airbar 100 could come into contact with each other when the airbar 100 was transitioned between supporting engagement (e.g., FIG. 3), full supporting engagement including wrap of the glass ribbon 120 around at least a portion of the airbar 100 (e.g., FIG. 4), and disengagement (e.g., no support) of the glass ribbon 120 relative to the airbar 100. Moreover, although defined with respect to the airbar 100 transitioning between states of engagement, it is to be understood that, in some embodiments, the airbar 100 may be stationary and the glass ribbon 120 may be moved relative to the airbar 100 to wrap around the airbar 100 to include the different states of engagement between the glass ribbon 120 and the airbar 100. That is, relative movement of at least one of the airbar 100 and the glass ribbon 120 can put the airbar 100 and the glass ribbon 120 into various states of disengagement and engagement that can include the planar configuration 150 of the glass ribbon 120 (e.g., as shown in FIG. 3) and the non-planar configuration 160 of the glass ribbon 120 (e.g., as shown in FIG. 4).

[0055] In some embodiments, an aperture diameter of about 0.0625 inches can be provided for one or more of the plurality of apertures 110. In further embodiments, an aperture diameter of about 0.0325 inches can be provided for one or more of the plurality of apertures 110. It is to be understood that any aperture diameter (e.g., from about 0.0325 inches to about 0.0625 inches) of the plurality of apertures 110, including aperture diameters not explicitly disclosed herein, can be provided for any one or more of the plurality of apertures 110, including a same diameter for all apertures of the plurality of apertures 110 as well as one or more different diameters for any one or more apertures of the plurality of apertures 110 without departing from the scope of the disclosure. In some embodiments, the airbar 100 can include, for example, 4 rows, 12 rows, 16 rows, 20 rows, 25 rows, or any number of rows of apertures, where each row extends along at least a portion of the width 116 of the circumferential portion 115 of the arcuate surface 105. In some embodiments, one or more rows can extend along the entire width 116 of the circumferential portion 115 of the arcuate surface 105. Moreover, each row can include any number of apertures (e.g., 1 -100 apertures, 50 apertures, 92 apertures, 100 apertures, etc.) per row can be provided in some embodiments) with the understanding that the number and size (e.g., diameter) of any one or more of the apertures of the plurality of apertures 110 can be based at least in part on a selected pressure of the cushion of air 125 that is provided to maintain a predetermined clearance between the glass ribbon 120 and the airbar 100. Similarly, the number and size (e.g. , diameter) of any one or more of the apertures of the plurality of apertures 110 can be based at least in part on the size of the airbar 100 (e.g., radius of curvature 106 of the arcuate surface 105) as well as the width 116 of the circumferential portion 115 of the arcuate surface 105. Accordingly, unless otherwise noted, the number of apertures, number of rows of apertures, etc. are not intended to limit the scope of the disclosure.

[0056] Hinging (e.g., a reduction in wrap angle of the glass ribbon 120 around at least a portion of the airbar 100 due to the nonzero bending stiffness of the glass ribbon 120) was observed in some experiments and can result in a concentrated reaction force at a point of tangency of the airbar 100 relative to the glass ribbon 120 that can lead to a reduction in clearance between the glass ribbon 120 and the arcuate surface 105 at or in the vicinity of the point of tangency. Accordingly, the reduction in clearance based at least in part on hinging of the glass ribbon 120 can occur, for example with respect to FIG. 4, at first tangent location 135 and second tangent location 145 when the glass ribbon 120 is being wrapped around at least a portion of the airbar 100 (e.g. , when the glass ribbon 120 is transitioning between states of engagement relative to the airbar 100) as well as when the glass ribbon 120 is wrapped around at least a portion of the airbar 100 (e.g., when the glass ribbon 120 is in a state of engagement relative to the airbar 100). With reference to FIG. 5, the reduction in clearance based at least in part on hinging of the glass ribbon 120 can occur along the first axis 171 and the second axis 172 when the glass ribbon 120 is wrapped around at least a portion of the airbar 100, (e.g., when the glass ribbon 120 is transitioning between or is in any one or more states of engagement relative to the airbar 100.)

[0057] Further, based on experimental testing, hinging of the glass ribbon 120 can depend, at least in part, on the bending stiffness of the glass ribbon 120, the modulus of the glass ribbon 120, and tension on the glass ribbon 120 per unit width, e.g., 0 kg/m, 1.8 kg/m, 3.6 kg/m or 0 to 3.6 kg/m ( 0 pounds per linear inch (pli), 0.1 pli, 0.2 pli, 0-0.2 pli) applied in a direction along the major surfaces (e.g., first major surface 122, second major surface 123) of the glass ribbon 120 transverse to the width 101 of the airbar 100. Thus, in some embodiments, to compensate for the effects of hinging (e.g., to maintain clearance between the glass ribbon 120 and the arcuate surface 105 of the airbar 100), additional plurality of apertures 110 can be provided at locations on the arcuate surface 105 to extend the circumferential portion 115 of the arcuate surface 105 including the plurality of apertures 110 beyond the first tangent location 135 (e.g., first axis 171) and beyond the second tangent location 145 (e.g. , second axis 172). In some embodiments, the additional plurality of apertures 110 provided on the arcuate surface 105 to extend the circumferential portion 115 of the arcuate surface 105 including the plurality of apertures 110 beyond the first tangent location 135 (e.g., first axis 171) and beyond the second tangent location 145 (e.g., second axis 172) can also reduce the occurrence of flutter (e.g. , air escaping from under the glass ribbon 120) at different angles of wrap of the glass ribbon 120 around at least a portion of the airbar 100.

[0058] Moreover, based on experimental testing, a flow model of the relationship between the glass ribbon 120 and the airbar 100 was developed. The flow model takes into account several variables including an area of the plurality of apertures 110 providing the cushion of air 125 to support the glass ribbon 120, nominal clearance of the glass ribbon 120 relative to the airbar 100, wrap angle of the glass ribbon 120 around at least a portion of the airbar 100, width 121 of the glass ribbon 120, radius of curvature 106 of the airbar 100, tension in the glass ribbon 120, and supply pressure of the air to provide the cushion of air 125. From the model, it was determined that, a desired nominal clearance of the glass ribbon 120 relative to the airbar 100 over varying wrap angles can be maintained when the open area of the plurality of apertures 110 is modified from, for example, a constant uniform distribution of open area of the plurality of apertures 110 over the entire wrap angle to a distribution of open area of the plurality of apertures 110 that is increased (e.g., greater) at or near the first tangent location 135. [0059] Accordingly, in some embodiments, a first density 111 of the plurality of apertures 110 of the first region 130 can be greater than a second density 112 of the plurality of apertures 110 of the second region 140. The first density 111 of the plurality of apertures 110 and the second density 112 of the plurality of apertures 110 can refer to a unit area of the plurality of apertures 110 defined as the total open area of apertures in a selected boundary. For example, as schematically illustrated in FIG. 5, the first density 111 of the plurality of apertures 110 can include a total open area of apertures in a selected boundary that is greater than a total open area of apertures in a corresponding selected boundary including the second density 112 of the plurality of apertures 110. It is to be understood that the selected boundary and the corresponding selected boundary can be identical in terms of area, size and shape, such that a comparison of total open area of the apertures within each respective boundary can define a normalized ratio of the first density 111 of the plurality of apertures 110 to the second density 112 of the plurality of apertures 110. When the airbar applies negative pressure, any apertures used to provide the negative pressure are not counted in the total open area of apertures for purposes of calculating the density of apertures.

[0060] Based on experimental testing, the airbar 100 with a first density 111 of the plurality of apertures 110 of the first region 130 greater than a second density 112 of the plurality of apertures 110 of the second region 140 can be oriented to maintain a desired clearance between the glass ribbon 120 and the airbar 100 (e.g., no contact) when the airbar 100 is transitioned between engagement (e.g., FIG. 3), full engagement (e.g., FIG. 4), and disengagement relative to the glass ribbon 120. In some embodiments, the first density 111 of the plurality of apertures 110 of the first region 130 can be from about two times to about four times greater than the second density 112 of the plurality of apertures 110 of the second region 140. In other embodiments, the first density 111 of the plurality of apertures 110 of the first region 130 can be about three times greater than the second density 112 of the plurality of apertures 110 of the second region 140.

[0061] In further embodiments, as shown in FIG. 5, the circumferential portion 115 of the arcuate surface 105 can be defined between a third axis 173 parallel to the axis of curvature 102 of the arcuate surface 105 at a third radius of curvature 183 of the arcuate surface 105 and a fourth axis 174 parallel to the axis of curvature 102 of the arcuate surface 105 at a fourth radius of curvature 184 of the arcuate surface 105. A first angle 195 between the first radius of curvature 181 and the third radius of curvature 183 can be about 5 degrees, a second angle 196 between the second radius of curvature 182 and the fourth radius of curvature 184 can be about 5 degrees, and a second central angle 192 between the third radius of curvature 183 and the fourth radius of curvature 184 can be about 55 degrees.

[0062] The first region 130 (e.g., one first region 130a) can be defined between the third axis 173 and a fifth axis 175 parallel to the axis of curvature 102 of the arcuate surface 105 at a fifth radius of curvature 185 of the arcuate surface 105. In some embodiments, a third angle 197 between the first radius of curvature 181 and the fifth radius of curvature 185 can be about 10 degrees, and a third central angle 193 between the third radius of curvature 183 and the fifth radius of curvature 185 can be about 15 degrees. In further embodiments, the second region 140 (e.g., one second region 140a) can be defined between the fourth axis 174 and the fifth axis 175.

[0063] In other embodiments, the first region 130 (e.g., another first region 130b) can be defined between the third axis 173 and a sixth axis 176 parallel to the axis of curvature 102 of the arcuate surface 105 at a sixth radius of curvature 186 of the arcuate surface 105. In some embodiments, a fourth angle 198 between the first radius of curvature 181 and the sixth radius of curvature 186 can be about 20 degrees, and a fourth central angle 194 between the third radius of curvature 183 and the sixth radius of curvature 186 can be about 25 degrees. In further embodiments, the second region 140 (e.g., another second region 140b) can be defined between the fourth axis 174 and the sixth axis 176.

[0064] FIG. 8 schematically illustrates a representative portion of the airbar 100 including an enlarged view of the plurality of apertures 110. As illustrated, the first density

111 of the plurality of apertures 110 of the first region 130 can be greater than the second density 112 of the plurality of apertures 110 of the second region 140. In some embodiments, the first density 111 of the plurality of apertures 110 that is greater than the second density

112 of the plurality of apertures 110 can provide a higher airflow in a particular location to compensate for a suction effect that exhausts air from the cushion of air 125 to ambient. Motion of the glass ribbon 120 (e.g. , as it is traversed over the airbar 100) can also impact the pressure of the cushion of air 125, the effects of which can be compensated for by the increased pressure from the first density 111 of the plurality of apertures 110 that is greater than the second density 112 of the plurality of apertures 110.

[0065] In some embodiments, the airbar 100, including any one or more features of the airbar 100, can be employed to proof test a glass ribbon 220. Proof testing (e.g. , proof stress testing) refers to a process by which a minimum strength of a material or sample can be determined. For example, with respect to glass (e.g. , glass sheets, glass ribbons, glass webs), proof testing can determine a minimum strength of the glass. Such minimum strength can be used to, for example, classify the glass, ensure the glass is capable to withstand a prescribed load, or provide a basis by which a user, customer, or other person can determine whether such glass can withstand various loads based at least in part on a particular application or environment in which the glass may be employed. Accordingly, a proof test (e.g., proof stress test) can define at least a minimum strength of glass. United States Patent No. 7,461,564, the contents of which are incorporated herein by reference in their entirety, discloses a method and apparatus for proof testing as sheet of brittle material. The method in the '564 patent includes bending a glass sheet over an arcuate member to detect sheets having a strength greater than a predetermined value.

[0066] As shown in FIG. 6 and FIG. 7, a method of proof testing a strength of a glass ribbon 220 can include the step of traversing the glass ribbon 220 over an airbar 200a, 200b. It is to be understood that the airbars 200a, 200b of a testing apparatus 200 for testing a strength of the glass ribbon 220 can include any one or more features of the airbar 100 disclosed herein. In some embodiments, the airbars 200a, 200b can be identical to the airbar 100 disclosed herein. In some embodiments, as shown in FIG. 6, the glass ribbon 220 can be traversed in a planar configuration 250 in a direction 215 between a first airbar 200a and a second airbar 200b. In other embodiments, as shown in FIG. 7, the glass ribbon 220 can be traversed in a non-planar configuration 260 in the direction 215 between the first airbar 200a and the second airbar 200b.

[0067] Accordingly, in still other embodiments, the method can further include imparting a plurality of bends 260a, 260b in the glass ribbon 220 while traversing the glass ribbon 220 over the airbars 200a, 200b. The plurality of bends 260a, 260b can produce a corresponding plurality of tensile stresses in the glass ribbon 220. The method can include determining a strength of the glass ribbon 220 based at least in part on the corresponding plurality of tensile stresses. As shown in FIG. 7, a first bend 260a in the glass ribbon 220 from the first airbar 200a can impart a tensile stress on a first major surface 222 of the glass ribbon 220 and a second bend 260b in the glass ribbon 220 from the second airbar 200b can impart a tensile stress on a second major surface 223 of the glass ribbon 220. The airbars 200a, 200b can be moved relative to the glass ribbon 220 from a position of disengagement where the glass ribbon 220 is unsupported by the airbars 200a, 200b or a position of supporting engagement by the airbars 200a, 200b in the planar configuration 250 (e.g., as shown in FIG. 6) to a position of full supporting engagement where the glass ribbon 220 can be supported by and wrap around at least a portion of the airbars 200a, 200b (e.g., as shown in FIG. 7) and include the corresponding first bend 260a and second bend 270b. [0068] In other embodiments, the method can further include incrementally increasing at least one of the corresponding plurality of tensile stresses and determining a strength of the glass ribbon 220 based at least in part on the increased at least one of the corresponding plurality of tensile stresses. In yet other embodiments, the method can further include incrementally increasing at least one of the corresponding plurality of tensile stresses until the glass ribbon 220 fails (e.g., cracks, chips, breaks, etc.). Moving at least one of the first airbar 200a and the second airbar 200b relative to the glass ribbon 220 to increase the amount of wrap of the glass ribbon 220 around at least a portion of the at least one of the first airbar 200a and the second airbar 200b can increase a corresponding tension in the glass ribbon 220 on the first major surface 222 of the glass ribbon 220 and the second major surface 223 of the glass ribbon 220.

[0069] Turning to FIG. 9, in still other embodiments, a vacuum box 300 to impart a bend 360 in a glass ribbon 320 can include an enclosure 305 including two opposing sides 306, 307 and an opening 310 between the two opposing sides 306, 307. The opening 310 can be oriented to define a plane 311 through which the glass ribbon 320 can cross from outside the enclosure 305 to inside the enclosure 305. A first airbar 300a and a second airbar 300b can be arranged at the opening 310 adjacent to one of the two opposing sides 306, 307 and can be oriented to provide a cushion of air to support the glass ribbon 320 as the glass ribbon 320 is conveyed along a direction 315 over the opening 310 of the enclosure 305. The airbars 300a, 300b can provide a non-contact transition for the glass ribbon 320 to enter the enclosure 305. The vacuum box 300 can further include a vacuum port 325 oriented to provide a negative pressure within the enclosure 305. The negative pressure can draw the glass ribbon 320 into the enclosure 305, impart the bend 360 in the glass ribbon 320, and support the glass ribbon 320 without contacting the glass ribbon 320 with a solid object as the glass ribbon 320 is conveyed along the direction 315.

[0070] In still other embodiments, the two opposing sides 306, 307 can be tapered relative to each other to narrow in a direction away from the opening 310. In other embodiments, the vacuum box 300 can include a vacuum source 330 to provide the negative pressure to the vacuum port 325. A pressure of the negative pressure from the vacuum source 330 can be adjusted to control, for example, a radius of the bend 360 of the glass ribbon 320. In further embodiments, the vacuum box 300 can be employed alone or with additional vacuum boxes to, for example, proof stress test the glass ribbon 320.

[0071] As shown in FIG. 10 and FIG. 11, in still other embodiments, a leveling apparatus 400 can include a leveling arm 405 to maintain a tension in a glass ribbon 420. An airbar 400a can be attached to a first end 406 of the leveling arm 405. The airbar 400a can be oriented to provide a cushion of air to support the glass ribbon 420, and can include a counter-balance 410 attached to a second end 407 of the leveling arm 405. The leveling arm 405 can include a pivot location 425 between the first end 406 and the second end 407 about which the first end 406 and the second end 407 can be oriented to rotate. In still other embodiments, a weight of the counter-balance 410 can be based at least in part on a force of the glass ribbon 420 acting on the airbar 400a. Accordingly, the weight of the counterbalance 410 can be provided to counteract the force of the glass ribbon 420 acting on the airbar 400a to maintain a tension in the glass ribbon 420. The weight of the counter-balance 410 can therefore automatically rotate about the pivot location 425 to automatically adjust the force on the glass ribbon 420 to maintain a predetermined tension in the glass ribbon 420 in the direction 415 along which the glass ribbon 420 can be conveyed over the airbar 400a.

[0072] Advantageously, maintaining a tension in the glass ribbon 420 can provide uniform rolling of the glass ribbon 420, for example, onto a spool. Accordingly, in still other embodiments the method can further include the steps of unwinding the glass ribbon 420 from a first spool 440 then traversing the glass ribbon 420 over the airbar 400a, and then rewinding the glass ribbon 420 onto a second spool 445. Maintaining tension in the glass ribbon 420 as the glass ribbon 420 is wound onto a spool can further provide consistent, subsequent unspooling of the glass ribbon 420 which can reduce shocks and other unwanted displacement of the glass ribbon 420.

[0073] It is to be understood that the airbars 300a, 300b of the vacuum box 300 as well as the airbar 400a of the leveling apparatus 400 can include any one or more features of the airbar 100 disclosed herein. In some embodiments, the airbars 300a, 300b of the vacuum box 300 as well as the airbar 400a of the leveling apparatus 400 can be identical to the airbar 100 disclosed herein.

[0074] It should be understood that while various embodiments have been described in detail with respect to certain illustrative and specific embodiments thereof, the present disclosure should not be considered limited to such, as numerous modifications and combinations of the disclosed features are possible without departing from the scope of the following claims.

Claims

CLAIMS What is claimed is:

1. An airbar to provide a cushion of air to support a glass ribbon, the airbar comprising: an arcuate surface comprising an axis of curvature;

a plurality of apertures arranged on a circumferential portion of the arcuate surface; a first region of the circumferential portion of the arcuate surface being oriented to provide the cushion of air to support the glass ribbon in a planar configuration;

the first region of the circumferential portion of the arcuate surface and a second region of the circumferential portion of the arcuate surface being oriented to provide the cushion of air to support the glass ribbon in a non-planar configuration; and wherein

a first density of the plurality of apertures of the first region is greater than a second density of the plurality of apertures of the second region.

2. The airbar of claim 1, wherein the first density of the plurality of apertures of the first region is from about two times to about four times greater than the second density of the plurality of apertures of the second region.

3. The airbar of claim 2, wherein the first density of the plurality of apertures of the first region is about three times greater than the second density of the plurality of apertures of the second region.

4. The airbar of claim 1, wherein the first region comprises a first axis parallel to the axis of curvature of the arcuate surface at a first radius of curvature of the arcuate surface, wherein the second region comprises a second axis parallel to the axis of curvature of the arcuate surface at a second radius of curvature of the arcuate surface, wherein a first central angle between the first radius of curvature and the second radius of curvature is about 45 degrees, and wherein the first radius of curvature is oriented to be perpendicular to a major surface of the glass ribbon when the first region of the circumferential portion of the arcuate surface is oriented to provide the cushion of air to support the glass ribbon in the planar configuration.

5. The airbar of claim 4, wherein the circumferential portion of the arcuate surface is defined between a third axis parallel to the axis of curvature of the arcuate surface at a third radius of curvature of the arcuate surface and a fourth axis parallel to the axis of curvature of the arcuate surface at a fourth radius of curvature of the arcuate surface, wherein a first angle between the first radius of curvature and the third radius of curvature is about 5 degrees, wherein a second angle between the second radius of curvature and the fourth radius of curvature is about 5 degrees, and wherein a second central angle between the third radius of curvature and the fourth radius of curvature is about 55 degrees.

6. The airbar of claim 5, wherein the first region is defined between the third axis and a fifth axis parallel to the axis of curvature of the arcuate surface at a fifth radius of curvature of the arcuate surface, wherein a third angle between the first radius of curvature and the fifth radius of curvature is about 10 degrees, and wherein a third central angle between the third radius of curvature and the fifth radius of curvature is about 15 degrees.

7. The airbar of claim 6, wherein the first density of the plurality of apertures of the first region is from about two times to about four times greater than the second density of the plurality of apertures of the second region.

8. The airbar of claim 7, wherein the second region is defined between the fourth axis and the fifth axis.

9. The airbar of claim 6, wherein the first density of the plurality of apertures of the first region is about three times greater than the second density of the plurality of apertures of the second region.

10. The airbar of claim 9, wherein the second region is defined between the fourth axis and the fifth axis.

1 1. The airbar of claim 5, wherein the first region is defined between the third axis and a sixth axis parallel to the axis of curvature of the arcuate surface at a sixth radius of curvature of the arcuate surface, wherein a fourth angle between the first radius of curvature and the sixth radius of curvature is about 20 degrees, and wherein a fourth central angle between the third radius of curvature and the sixth radius of curvature is about 25 degrees.

12. The airbar of claim 11, wherein the first density of the plurality of apertures of the first region is from about two times to about four times greater than the second density of the plurality of apertures of the second region.

13. The airbar of claim 12, wherein the second region is defined between the fourth axis and the sixth axis.

14. The airbar of claim 11, wherein the first density of the plurality of apertures of the first region is about three times greater than the second density of the plurality of apertures of the second region.

15. The airbar of claim 14, wherein the second region is defined between the fourth axis and the sixth axis.

16. A method of testing a strength of a glass ribbon comprising the step of:

traversing the glass ribbon over the airbar of any one of claims 1-15.

17. The method of claim 16, further comprising the steps of:

imparting a plurality of bends in the glass ribbon while traversing the glass ribbon over the airbar, wherein the plurality of bends produce a corresponding plurality of tensile stresses in the glass ribbon; and

determining a strength of the glass ribbon based at least in part on the corresponding plurality of tensile stresses.

18. The method of claim 17, further comprising the steps of:

incrementally increasing at least one of the corresponding plurality of tensile stresses; and

determining a strength of the glass ribbon based at least in part on the increased at least one of the corresponding plurality of tensile stresses.

19. The method of claim 17, further comprising the step of:

incrementally increasing at least one of the corresponding plurality of tensile stresses until the glass ribbon fails.

20. The method of claim 16, further comprising the steps of:

unwinding the glass ribbon from a first spool, then traversing the glass ribbon over the airbar, and then rewinding the glass ribbon onto a second spool.

21. A leveling arm to maintain a tension in a glass ribbon, the leveling arm comprising: the airbar of any one of claim 1 -15 attached to a first end of the leveling arm, the airbar being oriented to provide a cushion of air to support the glass ribbon; and

a counter-balance attached to a second end of the leveling arm, the leveling arm comprising a pivot location between the first end and the second end about which the first end and the second end are oriented to rotate.

22. The leveling arm of claim 21 , wherein a weight of the counter-balance is based at least in part on a force of the glass ribbon acting on the airbar.

23. A vacuum box to impart a bend in a glass ribbon comprising:

an enclosure comprising two opposing sides;

an opening between the two opposing sides, the opening being oriented to define a plane through which the glass ribbon crosses from outside the enclosure to inside the enclosure; and

a vacuum port oriented to provide a negative pressure within the enclosure, wherein at least one airbar of any one of claims 1 -15 is arranged at the opening of the enclosure adjacent to at least one of the two opposing sides, and wherein the at least one airbar is oriented to provide a cushion of air to support the glass ribbon.

24. The vacuum box of claim 23, wherein the two opposing sides are tapered relative to each other to narrow in a direction away from the opening.

25. The vacuum box of claim 23, further comprising a vacuum source to provide the negative pressure to the vacuum port.