WO2019005732A1

WO2019005732A1 - Apparatus and method for sheet separation with pulling force measurement

Info

Publication number: WO2019005732A1
Application number: PCT/US2018/039403
Authority: WO
Inventors: Robert Richard QUIEL
Original assignee: Corning Incorporated
Priority date: 2017-06-26
Filing date: 2018-06-26
Publication date: 2019-01-03
Also published as: TW201906704A; CN110799464A; JP2020525380A; KR20200013059A

Abstract

An apparatus and method for separating a glass sheet from a glass ribbon includes a gripping tool that imparts a pulling force on the glass ribbon sufficient to separate the glass sheet from the glass ribbon. The gripping tool includes at least one force measurement device that takes a plurality of force measurements while the gripping tool imparts a pulling force on the glass ribbon.

Description

APPARATUS AND METHOD FOR SHEET SEPARATION WITH PULLING FORCE

MEASUREMENT

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/524842, filed on June 26, 2017 the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present disclosure relates generally to apparatuses and methods for separating glass sheets from glass ribbons and more particularly to apparatuses and methods for measuring pulling forces during sheet separation processes.

Background

[0003] In the production of glass articles, such as glass sheets for display applications, including televisions and hand held devices, such as telephones and tablets, glass sheets can be separated from a continuously formed glass ribbon. Methods for separating glass sheets from a glass ribbon include scoring the ribbon along a desired line of separation and the pulling on the ribbon to form it into an arched shape, thus producing a bending stress within the glass that increases as the pulling force increases. When the bending stress, in combination with other stresses such as thermal expansion, is of sufficient magnitude and orientation, fracture will occur along the score line, resulting in a separated sheet of glass.

[0004] Because a number of variables can affect the bending and separation of glass sheets from a glass ribbon, such variables can, in turn, affect the quality of the separation, including the quality of the edge of the glass sheet along the separation line. For example, defects known to persons of ordinary skill in the art, such as those referred to as chips, hackle, or dog ears, can occur when one or more variables affecting the bending and separation of glass sheets are unaccounted for. Accordingly, it would be desirable to more fully understand the stresses imposed upon the glass during the separation process, which, in turn, can enable better understanding and control of variables affecting the bending and separation of glass sheets, thereby minimizing the generation of separation-related defects.

l SUMMARY

[0005] Embodiments disclosed herein include an apparatus for separating a glass sheet from a glass ribbon. The apparatus includes a gripping tool configured to impart a pulling force on the glass ribbon sufficient to separate the glass sheet from the glass ribbon. The gripping tool includes at least one force measurement device configured to take a plurality of force measurements while the gripping tool imparts a force on the glass ribbon.

[0006] Embodiments disclosed herein also include a gripping tool configured to impart a pulling force on a glass ribbon. The gripping tool includes at least one force measurement device configured to take a plurality of force measurements while the gripping tool imparts a force on the glass ribbon.

[0007] Embodiments disclosed herein also include a method of separating a glass sheet from a glass ribbon. The method includes imparting a pulling force on the glass ribbon with a gripping tool. The pulling force is sufficient to separate the glass sheet from the glass ribbon and the gripping tool includes at least one force measurement device that takes a plurality of force measurements while the gripping tool imparts a pulling force on the glass ribbon.

[0008] Additional features and advantages of the embodiments disclosed herein 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 disclosed embodiments as described herein, including the detailed description which 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 present embodiments intended to provide an overview or framework for understanding the nature and character of the claimed embodiments. The accompanying drawings are included to provide further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a schematic view of an example fusion down draw glass making apparatus and process; [0011] FIG. 2 is a schematic side view of a stage of an example glass sheet separation process;

[0012] FIG. 3 is a schematic side view of another stage of an example glass sheet separation process;

[0013] FIG. 4 is a schematic side view of yet another stage of an example glass sheet separation process;

[0014] FIG. 5 is a schematic side view of still yet another stage of an example glass sheet separation process;

[0015] FIG. 6 is a schematic front view of an example glass sheet gripping tool;

[0016] FIG. 7 is a schematic bottom cutaway view of a portion of an example glass sheet gripping tool with a sheet tensioning mechanism in a first position;

[0017] FIG. 8 is a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 with a sheet tensioning mechanism in a second position;

[0018] FIG. 9 is a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device in a first location;

[0019] FIG. 10 is a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device in a second location;

[0020] FIG. 11 is a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device in a third location;

[0021] FIG. 12 is a schematic side cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device in a fourth location; and

[0022] FIG. 13 is a chart showing measured strain as a function of time while a gripping tool imparts a pulling force on a glass ribbon.

DETAILED DESCRIPTION

[0023] Reference will now be made in detail to the present preferred embodiments of the present disclosure, 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. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0024] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, for example by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0025] Directional terms as used herein - for example 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.

[0026] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0027] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0028] As used herein, the term "vacuum source" refers to a source capable of generating at least a partial vacuum in an apparatus, system, or component that is in fluid communication with the vacuum source.

[0029] Shown in FIG. 1 is an exemplary glass manufacturing apparatus 10. In some examples, the glass manufacturing apparatus 10 can comprise a glass melting furnace 12 that can include a melting vessel 14. In addition to melting vessel 14, glass melting furnace 12 can optionally include one or more additional components such as heating elements (e.g. , combustion burners or electrodes) that heat raw materials and convert the raw materials into molten glass. In further examples, glass melting furnace 12 may include thermal management devices (e.g., insulation components) that reduce heat lost from a vicinity of the melting vessel. In still further examples, glass melting furnace 12 may include electronic devices and/or electromechanical devices that facilitate melting of the raw materials into a glass melt. Still further, glass melting furnace 12 may include support structures (e.g., support chassis, support member, etc.) or other components.

[0030] Glass melting vessel 14 is typically comprised of refractory material, such as a refractory ceramic material, for example a refractory ceramic material comprising alumina or zirconia. In some examples glass melting vessel 14 may be constructed from refractory ceramic bricks. Specific embodiments of glass melting vessel 14 will be described in more detail below.

[0031] In some examples, the glass melting furnace may be incorporated as a component of a glass manufacturing apparatus to fabricate a glass substrate, for example a glass ribbon of a continuous length. In some examples, the glass melting furnace of the disclosure may be incorporated as a component of a glass manufacturing apparatus comprising a slot draw apparatus, a float bath apparatus, a down-draw apparatus such as a fusion process, an up- draw apparatus, a press-rolling apparatus, a tube drawing apparatus or any other glass manufacturing apparatus that would benefit from the aspects disclosed herein. By way of example, FIG. 1 schematically illustrates glass melting furnace 12 as a component of a fusion down-draw glass manufacturing apparatus 10 for fusion drawing a glass ribbon for subsequent processing into individual glass sheets.

[0032] The glass manufacturing apparatus 10 (e.g., fusion down-draw apparatus 10) can optionally include an upstream glass manufacturing apparatus 16 that is positioned upstream relative to glass melting vessel 14. In some examples, a portion of, or the entire upstream glass manufacturing apparatus 16, may be incorporated as part of the glass melting furnace 12.

[0033] As shown in the illustrated example, the upstream glass manufacturing apparatus 16 can include a storage bin 18, a raw material delivery device 20 and a motor 22 connected to the raw material delivery device. Storage bin 18 may be configured to store a quantity of raw materials 24 that can be fed into melting vessel 14 of glass melting furnace 12, as indicated by arrow 26. Raw materials 24 typically comprise one or more glass forming metal oxides and one or more modifying agents. In some examples, raw material delivery device 20 can be powered by motor 22 such that raw material delivery device 20 delivers a predetermined amount of raw materials 24 from the storage bin 18 to melting vessel 14. In further examples, motor 22 can power raw material delivery device 20 to introduce raw materials 24 at a controlled rate based on a level of molten glass sensed downstream from melting vessel 14. Raw materials 24 within melting vessel 14 can thereafter be heated to form molten glass 28.

[0034] Glass manufacturing apparatus 10 can also optionally include a downstream glass manufacturing apparatus 30 positioned downstream relative to glass melting furnace 12. In some examples, a portion of downstream glass manufacturing apparatus 30 may be incorporated as part of glass melting furnace 12. In some instances, first connecting conduit 32 discussed below, or other portions of the downstream glass manufacturing apparatus 30, may be incorporated as part of glass melting furnace 12. Elements of the downstream glass manufacturing apparatus, including first connecting conduit 32, may be formed from a precious metal. Suitable precious metals include platinum group metals selected from the group of metals consisting of platinum, iridium, rhodium, osmium, ruthenium and palladium, or alloys thereof. For example, downstream components of the glass manufacturing apparatus may be formed from a platinum-rhodium alloy including from about 70 to about 90% by weight platinum and about 10% to about 30% by weight rhodium. However, other suitable metals can include molybdenum, palladium, rhenium, tantalum, titanium, tungsten and alloys thereof.

[0035] Downstream glass manufacturing apparatus 30 can include a first conditioning (i.e., processing) vessel, such as fining vessel 34, located downstream from melting vessel 14 and coupled to melting vessel 14 by way of the above-referenced first connecting conduit 32. In some examples, molten glass 28 may be gravity fed from melting vessel 14 to fining vessel 34 by way of first connecting conduit 32. For instance, gravity may cause molten glass 28 to pass through an interior pathway of first connecting conduit 32 from melting vessel 14 to fining vessel 34. It should be understood, however, that other conditioning vessels may be positioned downstream of melting vessel 14, for example between melting vessel 14 and fining vessel 34. In some embodiments, a conditioning vessel may be employed between the melting vessel and the fining vessel wherein molten glass from a primary melting vessel is further heated to continue the melting process, or cooled to a temperature lower than the temperature of the molten glass in the melting vessel before entering the fining vessel.

[0036] Bubbles may be removed from molten glass 28 within fining vessel 34 by various techniques. For example, raw materials 24 may include multivalent compounds (i.e. fining agents) such as tin oxide that, when heated, undergo a chemical reduction reaction and release oxygen. Other suitable fining agents include without limitation arsenic, antimony, iron and cerium. Fining vessel 34 is heated to a temperature greater than the melting vessel temperature, thereby heating the molten glass and the fining agent. Oxygen bubbles produced by the temperature-induced chemical reduction of the fining agent(s) rise through the molten glass within the fining vessel, wherein gases in the molten glass produced in the melting furnace can diffuse or coalesce into the oxygen bubbles produced by the fining agent. The enlarged gas bubbles can then rise to a free surface of the molten glass in the fining vessel and thereafter be vented out of the fining vessel. The oxygen bubbles can further induce mechanical mixing of the molten glass in the fining vessel.

[0037] Downstream glass manufacturing apparatus 30 can further include another conditioning vessel such as a mixing vessel 36 for mixing the molten glass. Mixing vessel 36 may be located downstream from the fining vessel 34. Mixing vessel 36 can be used to provide a homogenous glass melt composition, thereby reducing cords of chemical or thermal inhomogeneity that may otherwise exist within the fined molten glass exiting the fining vessel. As shown, fining vessel 34 may be coupled to mixing vessel 36 by way of a second connecting conduit 38. In some examples, molten glass 28 may be gravity fed from the fining vessel 34 to mixing vessel 36 by way of second connecting conduit 38. For instance, gravity may cause molten glass 28 to pass through an interior pathway of second connecting conduit 38 from fining vessel 34 to mixing vessel 36. It should be noted that while mixing vessel 36 is shown downstream of fining vessel 34, mixing vessel 36 may be positioned upstream from fining vessel 34. In some embodiments, downstream glass manufacturing apparatus 30 may include multiple mixing vessels, for example a mixing vessel upstream from fining vessel 34 and a mixing vessel downstream from fining vessel 34. These multiple mixing vessels may be of the same design, or they may be of different designs.

[0038] Downstream glass manufacturing apparatus 30 can further include another conditioning vessel such as delivery vessel 40 that may be located downstream from mixing vessel 36. Delivery vessel 40 may condition molten glass 28 to be fed into a downstream forming device. For instance, delivery vessel 40 can act as an accumulator and/or flow controller to adjust and/or provide a consistent flow of molten glass 28 to forming body 42 by way of exit conduit 44. As shown, mixing vessel 36 may be coupled to delivery vessel 40 by way of third connecting conduit 46. In some examples, molten glass 28 may be gravity fed from mixing vessel 36 to delivery vessel 40 by way of third connecting conduit 46. For instance, gravity may drive molten glass 28 through an interior pathway of third connecting conduit 46 from mixing vessel 36 to delivery vessel 40.

[0039] Downstream glass manufacturing apparatus 30 can further include forming apparatus 48 comprising the above-referenced forming body 42 and inlet conduit 50. Exit conduit 44 can be positioned to deliver molten glass 28 from delivery vessel 40 to inlet conduit 50 of forming apparatus 48. For example in examples, exit conduit 44 may be nested within and spaced apart from an inner surface of inlet conduit 50, thereby providing a free surface of molten glass positioned between the outer surface of exit conduit 44 and the inner surface of inlet conduit 50. Forming body 42 in a fusion down draw glass making apparatus can comprise a trough 52 positioned in an upper surface of the forming body and converging forming surfaces 54 that converge in a draw direction along a bottom edge 56 of the forming body. Molten glass delivered to the forming body trough via delivery vessel 40, exit conduit 44 and inlet conduit 50 overflows side walls of the trough and descends along the converging forming surfaces 54 as separate flows of molten glass. The separate flows of molten glass join below and along bottom edge 56 to produce a single ribbon of glass 58 that is drawn in a draw or flow direction 60 from bottom edge 56 by applying tension to the glass ribbon, such as by gravity, edge rolls 72 and pulling rolls 82, to control the dimensions of the glass ribbon as the glass cools and a viscosity of the glass increases. Accordingly, glass ribbon 58 goes through a visco-elastic transition and acquires mechanical properties that give the glass ribbon 58 stable dimensional characteristics. Glass ribbon 58 may, in some embodiments, be separated into individual glass sheets 62 by a glass separation apparatus 100 in an elastic region of the glass ribbon. A robot 64 may then transfer the individual glass sheets 62 to a conveyor system using gripping tool 65, whereupon the individual glass sheets may be further processed.

[0040] FIG. 2 shows a schematic side view of a stage of an example glass sheet separation process. As shown in FIG. 2, glass separation apparatus 100 includes scoring mechanism 102 and nosing 104, wherein scoring mechanism 102 and nosing 104 are positioned on opposite sides of glass ribbon 58. In the stage shown in FIG. 2, scoring mechanism 102 moves across the glass ribbon 58 in the widthwise direction and imparts a widthwise score line across the glass ribbon 58. In addition, in the stage shown in FIG. 2, gripping tool 65 has not yet engaged glass ribbon 58, although engagement while scoring is also known in the art and commonly practiced.

[0041] While scoring mechanism 102 is shown in FIG.2 as a mechanical scoring mechanism, such as a mechanism comprising a score wheel, it is to be understood that embodiments herein include other types of scoring mechanism, such as, for example, laser scoring mechanisms. When scoring mechanism 102 comprises a score wheel, the score wheel may be mounted on a ball bearing pivot which is secured to a shaft which is in turn mounted on a linear actuator (air cylinder) that moves the score wheel towards the glass ribbon 58 so it can be drawn across and score a side of the ribbon. [0042] Nosing 104 may comprise a resilient material, such as silicon rubber. In certain exemplary embodiments, nosing 104 may be a conformable nosing that has a bowed shape of the glass ribbon 58 as disclosed, for example, in U. S. patent no. 8,051,681, the entire disclosure of which is incorporated by reference. Nosing 104 may also be in fluid communication with a vacuum source (not shown) to enhance engagement between the glass ribbon 58 and the nosing, as disclosed, for example, in U. S. patent no. 8,245,539, the entire disclosure of which is incorporated herein by reference.

[0043] FIG. 3 shows a schematic side view of another stage of an example glass sheet separation process wherein scoring mechanism 102 has disengaged glass ribbon 58 and gripping tool 65, including gripping elements 66, is actuated by robot 64 to engage glass ribbon 58. Gripping elements 66 may, for example, comprise a resilient material, such as silicon rubber, and may, in certain exemplary embodiments, comprise a cup-shaped resilient material that may be in fluid communication with a vacuum source (not shown) to enhance engagement between the glass ribbon 58 and the gripping elements 66 (gripping elements comprising cup-shaped material in fluid communication with a vacuum source are hereinafter referred to as vacuum cups).

[0044] As shown in FIG. 3, while the gripping tool 64, including gripping elements 66, imparts a pulling force on glass ribbon 58, the pulling force is not sufficient to substantially bend the glass ribbon 58 away from the draw or flow direction 60. FIG. 4, however, shows a schematic side view of yet another stage of an example glass sheet separation process wherein gripping tool 65 has been further actuated by robot 64, thereby imparting a pulling force that is sufficient to begin to bend the portion of glass ribbon 58 extending below nosing 104 away from the draw or flow direction 60. However, as shown in FIG. 4, the pulling force is not yet sufficient to substantially separate the portion of the glass ribbon 58 extending below nosing 104 from the rest of the glass ribbon 58.

[0045] FIG. 5 shows a schematic side view of still yet another stage of an example glass sheet separation process wherein gripping tool 65 has been further actuated by robot 65, thereby imparting a pulling force that is sufficient to separate the portion of the glass ribbon 58 extending below nosing 104 (i.e., glass sheet) from the rest of the glass ribbon 58. The glass sheet may then be transferred to, for example, a conveyor system for further processing.

[0046] FIG. 6 shows a schematic front view of an example glass sheet gripping tool 65. Gripping tool 65 comprises four corner regions, respectively, A, B, C, and D, and each corner region comprises a gripping element 66. As shown in FIG. 6, gripping tool 65 further includes a gripping element 66 between the gripping elements in corner regions A and C and a gripping element 66 between the gripping elements in corner regions B and D for a total of six gripping elements. However, it is to be understood that embodiments disclosed herein include gripping tools comprising any number of gripping elements in any pattern or arrangement. For example, in certain embodiments, gripping tool 65 may include gripping elements in only corner regions A, B, C, D, for a total of four gripping elements. Gripping tool 65 may also include more than one gripping element between the gripping elements in corner regions A and C and more than one gripping element between the gripping elements in corner regions B and D (i.e., a column of a plurality of gripping elements between corner regions A and C and another column of a plurality of gripping elements between corner regions B and D). For example, the gripping tool 65 can include a gripping element centrally located on gripping tool 65.

[0047] FIG. 7 shows a schematic bottom cutaway view of a portion of an example glass sheet gripping tool 65 with a sheet tensioning mechanism in a first position. Sheet tensioning mechanism includes a sheet tensioning cylinder 74 and a movable slide plate 73 upon which is mounted a gripping element mounting block 68 that is in fluid communication with a vacuum fitting 69 and gripping element connector 67 (e.g., tightening nut) that is mounted on gripping element mounting block 68. Gripping element 66 (e.g., vacuum cup) is mounted on and in fluid communication with gripping element connector 67 and vacuum fitting 69 is in fluid communication with vacuum source (not shown), thereby allowing fluid communication between gripping element 66 and vacuum source via vacuum fitting 69, gripping element mounting block 68, and gripping element connector 67. Gripping tool 65 also includes arm 71, arm mounting block 70, and end face 72.

[0048] FIG. 8 shows a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 with a sheet tensioning mechanism in a second position. As shown in FIG. 8, sheet tensioning cylinder 74 actuates lateral movement of slide plate 73 and corresponding movement of gripping element mounting block 68, vacuum fitting 69, gripping element connector 67, and gripping element 66 in the direction indicated by arrow M. A sheet tensioning mechanism on the opposite side of gripping tool 65 can, for example, correspondingly move in the opposite direction as the direction indicated by arrow M.

Lateral movement of sheet tensioning mechanism can enable increased flattening of a glass sheet engaged by gripping elements 66. Such lateral movement can, for example, occur after the glass sheet has separated from glass ribbon 58, or can occur between when gripping tool 65 initially engages glass ribbon 58 (e.g., as shown in FIG. 3) and when gripping tool 65 imparts a pulling force that is sufficient to begin to bend the portion of glass ribbon 58 extending below nosing 104 away from the draw or flow direction 60 (e.g., as shown in FIG. 4).

[0049] As the gripping tool 65 imparts a pulling force on the glass ribbon 58 (e.g., as shown in FIGS. 3-5) it induces bending stresses on the glass ribbon 58 and measurement of the pulling force or forces on the glass ribbon 58 provides quantitative information regarding the bending stresses experienced by the glass ribbon 58 during the sheet separation process. Pulling force measurement can be achieved according to embodiments disclosed herein, wherein the gripping tool 65 includes at least one force measurement device configured to take a plurality of pulling force measurements while the gripping tool 65 imparts a pulling force on the glass ribbon 58.

[0050] FIG. 9 shows a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device 75a in a first location. As shown in FIG. 9, force measurement device 75a is positioned between gripping element 66 and gripping element mounting block 68. Force measurement device 75a can be, for example, a ring type load cell that circumferentially surrounds gripping element connector 67, such as a miniature low-profile through-hole compression load cell available from Omega Engineering.

[0051] FIG. 10 shows a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device 75b in a second location. As shown in FIG. 10, force measurement device 75b is positioned between slide plate 73 and gripping element mounting block 68. Force measurement device 75b can be, for example, a mini low profile universal load cell, operable in tension or compression mode, such as an MLP Series low profile universal load cell available from Transducer Techniques.

[0052] FIG. 11 shows a schematic bottom cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device 75b in a third location. As shown in FIG. 11 , force measurement device 75b is positioned at the location of arm mounting block 70 and, in this regard, may be positioned on or in place of arm mounting block 70. As with the force measurement device 75b illustrated in FIG. 10, force

measurement device 75b can be, for example, a mini low profile universal load cell, operable in tension or compression mode, such as an MLP Series low profile universal load cell available from Transducer Techniques.

[0053] FIG. 12 shows a schematic side cutaway view of the example glass sheet gripping tool portion of FIG. 7 including a force measurement device 75c in a fourth location. As shown in FIG. 12, force measurement device 75 c is positioned on or within arm 71. Force measurement device 75c can be, for example, a thin beam sensor calibrated to correlate the flexure of arm 71 with a pulling or pushing force on gripping element 66, such as a TBS Series full bridge thin beam sensor available from Transducer Techniques or a full bridge thin beam load cell available from Omega Engineering. While FIG. 12 shows force measurement device 75c at a specific location, force measurement device 75c can be mounted at any location where the flexure of arm 71 is strongly correlated with pulling or pushing force on gripping element 66. Such correlation can be enhanced by increasing the degree of strain within arm 71 at or near the location of the force measurement device such as, for example, by making a cut 76 into the opposite side of arm 71 as force measurement device 75c.

[0054] When positioning force measurement device (e.g., 75a, 75b, 75c), care should be taken to adequately protect the device from heat sources, particularly heat radiating from glass ribbon 58 as force measurement devices can be temperature sensitive. Using relatively less temperature sensitive force measurement devices can also be beneficial. In addition, care should be taken to adequately protect the device from glass fragments and other materials.

[0055] Embodiments disclosed herein include those in which each gripping element 66 of a gripping tool 65 is associated with a corresponding force measurement device, such as the force measurement devices 75a, 75b, and 75c illustrated in FIGS. 9-12. For example, embodiments disclosed herein include those in which gripping tool 65 includes four corner regions (such as is shown, for example, in FIG. 6) and each corner region comprises a gripping element 66 and a corresponding force measurement device. Embodiments disclosed herein also include those in which gripping tool 65 includes any number of a plurality of gripping elements and each gripping element 66 is associated with a corresponding force measurement device.

[0056] Embodiments disclosed herein include those in which there is no sheet tensioning mechanism and gripping element mounting block 68 is, for example, attached directly to arm mounting block 70 or gripping element mounting block 68 is attached directly to arm 71.

[0057] The at least one force measurement device, such as the force measurement devices 75a, 75b, and 75c illustrated in FIGS. 9-12, can take a plurality of force measurements while the gripping tool 65 imparts a pulling force on the glass ribbon 58, such as at least 2, and further such as at least 5, and yet further such as at least 10, and still yet further such as at least 100, and even still yet further such as at least 1000 pulling force measurements while the gripping tool 65 imparts a pulling force on the glass ribbon 58. Accordingly, embodiments disclosed herein include those in which gripping tool 65 includes any number of a plurality of gripping elements 66 and two or more gripping elements 66 are associated with corresponding force measurement devices, wherein each force measurement device takes a plurality of force measurements while the gripping tool 65 imparts a pulling force on the glass ribbon 58.

[0058] FIG. 13 is a chart showing measured strain as a function of time while a gripping tool, similar to the gripping tool 65 illustrated in FIG. 6, imparts a pulling force on a glass ribbon. In order to generate the data shown in FIG. 13, the gripping tool was equipped with thin beam sensors positioned on opposing arms of the gripping tool and calibrated to correlate the measured flexure of the arms with a known pulling force. As can be seen from FIG. 13, the points in time when the gripping tool imparts force on the glass ribbon to bend it, when a glass sheet is separated from the ribbon, and when the robot has moved the glass sheet away from the glass ribbon are clearly discernible.

[0059] Embodiments disclosed herein can enable better understanding of not only the stresses experienced by a glass ribbon during bending and separation processes, but also factors that affect the quality of separation of glass sheets from a glass ribbon, such as, for example, factors that can affect separation associated defects such as chips, hackle, or dog ears. Such factors include, for example, position and orientation of the gripping tool when initially engaging the glass ribbon, position of the nosing, position of pulling rolls, and maximum degree to which the gripping tool will bend the glass ribbon and the rate at which this bending occurs. Accordingly, embodiments disclosed herein include analyzing a plurality of force measurements, including forces while the gripping tool is first engaging the glass ribbon and forces while the glass ribbon is being scored, wherein such analysis can result in improved understanding and control of factors that affect the quality of separation of glass sheets from a glass ribbon.

[0060] While the above embodiments have been described with reference to a fusion down draw process, it is to be understood that such embodiments are also applicable to other glass forming processes, such as float processes, slot draw processes, up-draw processes, tube drawing processes, and press-rolling processes.

[0061] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiment of the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. An apparatus for separating a glass sheet from a glass ribbon comprising:

a gripping tool configured to impart a pulling force on the glass ribbon sufficient to separate the glass sheet from the glass ribbon, wherein the gripping tool comprises at least one force measurement device configured to take a plurality of force measurements while the gripping tool imparts a pulling force on the glass ribbon.

2. The apparatus of claim 1, wherein the gripping tool comprises a plurality of gripping elements.

3. The apparatus of claims 1 or 2, wherein each of the gripping elements

comprises a vacuum cup.

4. The apparatus of claims 2 or 3, wherein the gripping tool comprises four corner regions and each comer region comprises a gripping element.

5. The apparatus of any one of claims 2 to 4, wherein two or more gripping

elements are associated with corresponding force measurement devices.

6. The apparatus of any one of claims 1 to 5, wherein the at least one force

measurement device comprises a load cell.

7. The apparatus of any one of claims 1 to 6, wherein the gripping tool comprises a sheet tensioning mechanism.

8. The apparatus of any one of claims 1 to 7, wherein the apparatus further

comprises a scoring mechanism.

9. A gripping tool configured to impart a pulling force on a glass ribbon wherein the gripping tool comprises at least one force measurement device configured to take a plurality of force measurements while the gripping tool imparts a pulling force on the glass ribbon.

10. The gripping tool of claim 9, wherein the gripping tool comprises a plurality of gripping elements.

11. The gripping tool of claims 9 or 10, wherein each of the gripping elements comprises a vacuum cup.

12. The gripping tool of claims 10 or 11 , wherein the gripping tool comprises four corner regions and each corner region comprises a gripping element.

13. The gripping tool of any one of claims 10 to 12, wherein two or more gripping elements are associated with corresponding force measurement devices.

14. The gripping tool of any one of claims 9 to 13, wherein the at least one force measurement device comprises a load cell.

15. The gripping tool of any one of claims 9 to 14, wherein the gripping tool comprises a sheet tensioning mechanism.

16. A method of separating a glass sheet from a glass ribbon comprising imparting a pulling force on the glass ribbon with a gripping tool, wherein the pulling force is sufficient to separate the glass sheet from the glass ribbon and wherein the gripping tool comprises at least one force measurement device that takes a plurality of force measurements while the gripping tool imparts a pulling force on the glass ribbon.

17. The method of claim 16, wherein the gripping tool comprises a plurality of gripping elements.

18. The method of claims 16 or 17, wherein each of the gripping elements

comprises a vacuum cup.

19. The method of claims 17 or 18, wherein the gripping tool comprises four corner regions and each comer region comprises a gripping element.

20. The method of any one of claims 17 to 19, wherein two or more gripping elements are associated with corresponding force measurement devices.

21. The method of claim 20, wherein the method further comprises analyzing the plurality of force measurements.

22. The method of any one of claims 16 to 21 , wherein the at least one force measurement device comprises a load cell.

23. The method of any one of claims 16 to 22, wherein the method further

comprises tensioning the glass ribbon with a sheet tensioning mechanism.