WO2013130688A1

WO2013130688A1 - Methods of finishing a sheet of material with magnetorheological finishing

Info

Publication number: WO2013130688A1
Application number: PCT/US2013/028129
Authority: WO
Inventors: Aric Bruce Shorey; Daniel Duane Strong; David A. Tammaro
Original assignee: Corning Incorporated
Priority date: 2012-02-29
Filing date: 2013-02-28
Publication date: 2013-09-06
Also published as: CN104136167A; EP2819809A1; US20130225049A1; JP2015513471A; KR20140136447A; TW201347943A

Abstract

Methods of finishing a sheet of material, such as a glass sheet, include finishing an edge portion of the sheet of material with magnetorheological finishing. In one example, the average thickness of the sheet of material between a first face and a second face is from 50μm to about 500 μm. In another example, the method consists essentially of a single step of finishing the edge portion of the glass sheet with magnetorheological finishing such that the entire edge portion is shaped between the first face and the second face during the a single magnetorheological finishing step.

Description

METHODS OF FINISHING A SHEET OF MATERIAL WITH

MAGNETORHEOLOGICAL FINISHING

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

Provisional Application Serial No. 61/604,863 filed on February 29, 2012, and the benefit of priority under 35 U.S.C. § 120 of U.S. Application Serial No. 13/721,557 filed on December 20, 2012, the contents of which are relied upon and incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present disclosure relates generally to methods of finishing a sheet of material and, more particularly, to methods of finishing an edge portion of a sheet of material with magnetorheological finishing.

BACKGROUND

[0003] It is known to produce a sheet of material, such as display-quality glass sheets, by various techniques. Once formed, a glass sheet is typically separated to trim edge portions from the glass sheet and/or to resize the glass sheet to accommodate a particular application. Typical separation procedures can result in undesirable rough/sharp edge portions that are vulnerable to cracking.

SUMMARY

[0004] Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0005] In one aspect, a method of finishing a sheet of material comprises the step (I) of providing a sheet of material with a first face and a second face, wherein an average thickness of the sheet of material between the first face and the second face is from about 50 μιη to about 500 μιη. The method further comprises the step (II) of finishing an edge portion of the sheet of material with magnetorheological finishing.

[0006] In one example of the aspect, step (I) provides the sheet of material as a glass sheet.

[0007] In another example of the aspect, step (I) provides the average thickness of the sheet of material from about 50 μιη to about 300 μιη. [0008] In still another example of the aspect, step (I) provides the average thickness of the sheet of material from about 75 μιη to about 200 μιη.

[0009] In yet another example of the aspect, step (I) provides the average thickness of the sheet of material from about 75 μιη to about 150 μιη.

[0010] In still another example of the aspect, step (I) provides the sheet of material positioned along a plane at a predetermined orientation within an angular range of from about + 45° to about - 45° with respect to a vertical axis.

[0011] In another example of the aspect, the predetermined orientation of the sheet of material is maintained during step (II).

[0012] In yet another example of the aspect, step (I) provides the edge portion extending along a peripheral portion of the sheet of material between the first face and the second face.

[0013] In another example of the aspect, the method includes a step of strengthening the edge portion before step (II).

[0014] In a further example of the aspect, the method includes a step of separating the sheet of material to provide the edge portion before step (II).

[0015] In still a further example of the aspect, the step of separating occurs after step (I).

[0016] In another further example of the aspect, the method further includes a step of strengthening the edge portion after the step of separating and before step (Π).

[0017] In yet another example of the aspect, the method further includes a step of edging the sheet of material to provide the edge portion before step (II).

[0018] In a further example of the aspect, the step of edging occurs after step (I).

[0019] In yet another example of the aspect, the method includes a step of separating the sheet of material before the step of edging the sheet of material.

[0020] In still another example of the aspect, the method includes a step of strengthening the edge portion after the step of edging and before step (II).

[0021] In another aspect, a method is provided for finishing an edge portion of a glass sheet having a first face and a second face with the edge portion extending along a peripheral portion of the glass sheet between the first face and the second face. The method consists essentially of a single step of finishing the edge portion of the glass sheet with magneto rheological finishing such that the entire edge portion is shaped between the first face and the second face during the a single magnetorheological finishing step. [0022] In yet another aspect, a method for finishing an edge portion of a glass sheet consists essentially of the steps of: (I) providing a glass sheet with a first face and a second face, wherein an average thickness of the glass sheet between the first face and the second face is from about 50 μιη to about 500 μιη; and (II) finishing an edge portion of the glass sheet with magnetorheological finishing.

[0023] In one example of the aspect, during step (II), the entire edge portion is shaped between the first face and the second face during a single magnetorheological finishing step.

[0024] In another example of the aspect, step (I) provides the average thickness of the glass sheet from about 75 μιη to about 150 μιη.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other aspects are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0026] FIG. 1 illustrates a glass manufacturing apparatus configured to produce a glass sheet that may be used with methods in accordance with the disclosure;

[0027] FIG. 2 illustrates methods of separating edge members from a separated glass sheet with a first separation device and a second separation device while supporting the separated glass sheet in accordance with methods of the disclosure;

[0028] FIG. 3 illustrates edge members after separating from the remaining portion of the glass sheet with the methods of separating illustrated in FIG. 2;

[0029] FIG. 4 illustrates a side view of the first separation device of FIG. 2;

[0030] FIG. 5 illustrates a side view of the second separation device of FIG. 2;

[0031] FIG. 6 illustrates a method step of breaking away the edge member after scoring with the second separation device of FIG. 5;

[0032] FIG. 7 illustrates a side view of the separated glass sheet and a magnetorheological finishing apparatus and further illustrates a method step of finishing an edge portion of the separated glass sheet with magnetorheological finishing;

[0033] FIG. 8 is a front view of the separated glass sheet and magnetorheological finishing apparatus of FIG. 7;

[0034] FIG. 9 is a first example flow chart illustrating example methods of the disclosure;

[0035] FIG. 10 is a second example flow chart illustrated further example methods of the disclosure; [0036] FIG. 11 is an enlarged view of an edge portion of a glass sheet after separating and before finishing, wherein the glass sheet has a thickness of about 100 μηι between a first face and a second face of the glass sheet; and

[0037] FIG. 12 is an enlarged view of the edge portion of FIG. 11 after magnetorheological finishing.

DETAILED DESCRIPTION

[0038] Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0039] Methods are provided for finishing a sheet of material. The sheets of material of the present invention may comprise various materials such as glasses, glass-ceramics, ceramics, silicon, semiconductor materials, and combinations of the preceding materials. In one particular example, the sheet of material can comprise a glass sheet, such as a display-quality glass sheet. Such display-quality glass sheets can be transparent and incorporated in liquid crystal display devices and/or other electronic devices. Example methods of the present invention will be described with reference to the sheet of material comprising display-quality glass sheet material although it will be appreciated that the sheet of material may comprise other glass sheets and/or other materials such as the alternative materials mentioned above.

[0040] The glass sheet may be formed by a wide range of techniques. As shown in FIG. 1, there is shown a schematic view of an exemplary glass manufacturing apparatus 101 that may be used in accordance with aspects of the disclosure. The exemplary glass manufacturing apparatus 101 is illustrated as a down draw fusion apparatus although other forming apparatus may be used in further examples.

[0041] The glass manufacturing apparatus 101 can include a melting vessel 103, a fining vessel 105, a mixing vessel 107, a delivery vessel 109, a forming device 111, a pull roll device 113 and a separating device 115.

[0042] The melting vessel 103 is where the glass batch materials are introduced as shown by arrow 117 and melted to form molten glass 119. The fining vessel 105 has a high temperature processing area that receives the molten glass 119 (not shown at this point) from the melting vessel 103 and in which bubbles are removed from the molten glass 119. The fining vessel 105 is connected to the mixing vessel 107 by a finer to stir chamber connecting tube 121. The mixing vessel 107 is connected to the delivery vessel 109 by a stir chamber to bowl connecting tube 123. The delivery vessel 109 delivers the molten glass 119 through a downcomer 125 to an inlet 127 and into the forming device 111.

[0043] Various forming devices may be used in accordance with aspects of the disclosure. For example, as shown in FIG. 1, the forming device 111 includes an opening 129 that receives the molten glass 119 which flows into a trough 131. The molten glass 119 from the trough 131 then overflows and runs down two sides 132 (one side shown in FIG. 1) before fusing together at a root 133 of the forming device 111. The root 133 is where the two sides 132 come together and where the two overflow walls of molten glass 119 flowing over each of the two sides 132 fuse together as the glass ribbon 106 is drawn downward off the root 133.

[0044] A portion of the glass ribbon 106 is drawn off the root 133 into a viscous zone 135 wherein the glass ribbon 106 begins thinning to a final thickness. The portion of the glass ribbon 106 is then drawn from the viscous zone 135 into a setting zone 137. In the setting zone 137, the portion of the glass ribbon 106 is set from a viscous state to an elastic state with the desired profile. The portion of the glass ribbon 106 is then drawn from the setting zone 137 to an elastic zone 139. Once in the elastic zone 139, the glass ribbon 106 may be deformed, within limits, without permanently changing the profile of the glass ribbon 106.

[0045] After the portion of the glass ribbon 106 enters the elastic zone 139, the separating device 115 may be provided to sequentially separate a plurality of separated glass sheets 141 from the glass ribbon 106 over a period of time. The separating device 115 may include the illustrated traveling anvil machine although further separating devices may be provided in further examples.

[0046] As further illustrated in FIG. 1, the glass manufacturing apparatus 101 may be provided with support devices 143, such as a suction cup apparatus, air bearing, or other support device, to help support the glass sheet, such as the glass ribbon 106 and/or the separated glass sheets 141. For purposes of this application, "glass sheet" can be considered to include the glass ribbon and/or the separated glass sheets that are separated from the glass ribbon. As such, when discussing applicability and methods of the present disclosure with the glass sheet, it is understood that the methods can be interpreted as being carried out with various forms of the glass sheet (e.g., the glass ribbon 106, separated glass sheets 141 that are separated from the glass ribbon, or glass sheets formed by other techniques).

[0047] As such, while various methods of the disclosure are described with respect to the separated glass sheets 141, it is understood that the methods of the disclosure may be carried out with other forms of the glass sheets (e.g., the glass ribbon 106 or glass sheets formed with other techniques).

[0048] As discussed above, the glass sheet can be initially formed as a glass ribbon 106 by way of the example glass manufacturing apparatus, although glass sheets may be formed by other techniques. A separating device 115, such as the illustrated traveling anvil machine can be used to separate the glass ribbon 106 into the separated glass sheets 141. As such, the traveling anvil machine may create a first edge portion 141a and a second edge portion 141b, wherein the length of the separated glass ribbon 141 is defined between the first and second edge portions 141a, 141b. It will be appreciated that in further examples, the width of the separated glass ribbon 141 can be defined between the first and second edge portions 141a, 141b. As further shown in FIG. 1, the glass manufacturing apparatus 101 may include a magnetorheological finishing apparatus 145 that may be part of the glass manufacturing apparatus 101 although the magnetorheological finishing apparatus 145 may be provided at a downstream processing location from the glass manufacturing apparatus 101 in further examples. In such examples, the support devices 143 may be operated to transport the separated glass sheet 141 such that the first and/or second edge portions 141a, 141b are finished with the magnetorheological finishing apparatus 145. In some examples, the support devices 143 can support the glass ribbon 106 and then continue to support the separated glass sheet 141 throughout the entire separating and finishing process techniques illustrated in FIGS. 2-8 described more fully below.

[0049] As shown in FIG. 2 and 3, the first and second edge members 201, 203 may further be removed by various techniques. Removal of the second edge members may be desired to remove thickness inconsistencies in the edge members that may result from the formation of the glass ribbon with the glass manufacturing apparatus 101. Alternatively, similar separation techniques may be employed to subdivide the separated glass sheets into a plurality of smaller glass sheets depending on the particular application. Although not shown in FIGS. 2 and 3, the magnetorheological finishing apparatus 145 may be provided at the station where the edge members are removed. For example the magnetorheological finishing apparatus 145 may be used to finish one or both of the first and second edge portion 141a, 141b while the edge members are being removed as illustrated in FIG. 2. In addition or alternatively, the magnetorheological finishing apparatus 145 may be used to finish one or both of the second and third edge portions 301a, 301b shown in FIG. 3.

[0050] Various glass separation devices may be used in accordance with aspects of the present disclosure in order to separate the first and second edge members from the remaining portion of the separated glass sheet 141. FIGS. 2 and 4 illustrate just one glass separation technique that may include use of a first separation device 205 that can include a laser 401 configured to heat a surface of the separated glass sheet 141 and a liquid cooling device 403 configured to propagate a crack to separate the first edge member 201 from the remaining portion of the separated glass sheet 141.

[0051] FIGS. 2, 5 and 6 illustrated another example of a second separation device 207 comprising a scoring device 501 that can create a score line 209 along a separation path. Once formation of the score line is complete, a pivot member 601 can be applied on the opposite side of the score line 209 and a force 603 can be applied to break away the second edge member 203 from the remaining portion of the separated glass sheet 141.

[0052] As shown in FIG. 3, once the first and second edge members 201, 203 are removed, the separated glass sheet 141 includes a third edge portion 301a and a fourth edge portion 301b, wherein the width of the separated glass ribbon 141 is defined between the third and fourth edge portions 301a, 301b. It will be appreciated that in further examples, the length of the separated glass ribbon 141 can be defined between the third and fourth edge portions 301a, 301b.

[0053] The traveling anvil machine (e.g., see the separation device 115 shown in FIG. 1), the first separation device 205 and the second separation device 207 are mere examples of various possible separation devices that may be used to separate the glass sheets. Regardless of the techniques used, each edge portion 141a, 141b, 301a, 301b may include undesirable rough/sharp edge portions that are vulnerable to cracking of the glass sheet.

[0054] Methods of the present disclosure can be used with a sheet of material (e.g., glass sheet comprising a glass ribbon, separated glass sheet, etc.) with a wide range of average thicknesses such as average thicknesses above 500 μηι. For example, the average thicknesses can be from greater than 500 μιη to about 2 mm, such as from about 700 μιη to about 1.5 mm, such as from about 900 μιη to about 1.2 mm, such as about 1.1 mm.

[0055] Removal of undesirable rough/sharp edge portions may be complicated for relatively thin glass sheets that can be brittle and/or relatively fragile. There is an increasing demand for relatively thin glass sheets with particular performance characteristics. For example, as shown in FIG. 4, the relatively thin separated glass sheets 141 can have average thicknesses "T" between a first face 405 and a second face 407, wherein an average thickness of the glass sheet between the first face 405 and the second face 407 is less than or equal to about 500 μιη, such as less than or equal to about 400 μιη, such as less than or equal to about 300 μιη, such as less than or equal to about 200 μιη, such as less than or equal to about 100 μιη, such as less than or equal to about 75 μιη. In one example, the average thickness "T" between the first face 405 and the second face 407 is from about 50 μιη to about 500 μιη, such as from about 50 μιη to about 400 μιη, such as from about 50 μιη to about 300 μιη, such as from about 50 μιη to about 200 μιη, such as from about 50 μιη to about 100 μιη, such as from about 50 μιη to about 75 μιη, such as from about 75 μιη to about 500 μιη, such as from about 75 μιη to about 400 μιη, such as from about 75 μιη to about 300 μιη, such as from about 75 μιη to about 200 μιη, such as from about 75 μιη to about 150 μιη, such as from about 75 μιη to about 100 μιη, such as from about 100 μιη to about 500 μιη, such as from about 100 μιη to about 400 μιη, such as from about 100 μιη to about 300 μιη, such as from about 100 μιη to about 200 μιη. Providing glass sheets having a thin average thickness "T" can be desirable to enhance performance characteristics.

[0056] Finishing the edge portions 141a, 141b, 301a, 301b can include the step of finishing the edge portion with a magnetorheological finishing (MRF) technique. For example, MRF apparatus and/or methods set forth in U.S. Patent Application No. 13/112,498 filed May 20, 201 1 and/or U.S. Patent Application No. 13/169,499 filed June 27, 2011 may be incorporated in accordance with aspects of the disclosure. U.S. Patent Application No. 13/1 12,498 filed May 20, 201 1 and U.S. Patent Application No. 13/169,499 filed June 27, 2011 are each herein incorporated by reference in its entirety.

[0057] MRF may remove damage and/or imperfections such undesirable rough/sharp edge portions generated when separating the glass sheet. MRF can also reduce processing time and/or overcome process complications that may otherwise result when attempting to finish the edge portions of relatively thin glass sheets. For example, MRF can remove relatively little material to achieve the desired finished edge profile. Furthermore, MRF can be used for machining the relatively fragile edge portions of relatively thin glass sheets. Still further, MRF can be used to reduce processing time regardless of the average thickness of the separated glass sheet 141.

[0058] MRF uses a fluid-based conformable tool, called a magnetorheological fluid (Hereinafter "MR fluid"), for finishing. MR fluid can include micron-sized magnetizable particles and micron-sized to nano-sized abrasive particles suspended in a liquid vehicle. For example, the sizes of the magnetizable particles may be in a range from 1 μιη to 100 μιη or greater, for example, 1 μιη to 150 μιη, for example, 5 μιη to 150 μιη, for example, 5 μιη to 100 μιη, for example, 5 μιη to 50 μιη, for example, 5 μιη to 25 μιη, for example, 10 μιη to 25 μιη and the sizes of the abrasive particles may be in a range from 15 nm to 10 μιη. The magnetizable particles may have a uniform or a non-uniform particle size distribution, the same or different shapes, and regular or irregular shapes. Also, the magnetizable particles may be made of a single magnetizable material or a combination of different magnetizable materials. Examples of magnetizable materials include iron, iron oxide, iron nitride, iron carbide, carbonyl iron, chromium dioxide, low-carbon steel, silicon steel, nickel, cobalt, and a combination of the preceding materials. The magnetizable particles may also be coated or encapsulated, for example, with or in a protective material. In one embodiment, the protective material is a material that is chemically and physically stable in the liquid vehicle and that does not react chemically with the magnetizable material. Examples of suitable protective materials include zirconia, alumina, and silica. Similarly, the abrasive particles may have a uniform or a non-uniform particle size distribution, the same or different shapes, and regular or irregular shapes. Also, the abrasive particles may be made of a single non-magnetizable material or a combination of different non-magnetizable materials. Examples of abrasive materials include cerium oxide, diamond, silicon carbide, alumina, zirconia, and a combination of the preceding materials. Other abrasive materials not specifically included in this list and known to be useful in polishing a surface may also be used. The liquid vehicle included in a MR fluid may be aqueous or non-aqueous. Examples of vehicles include mineral oil, synthetic oil, water, and ethylene glycol. The vehicles may further include stabilizers, e.g., stabilizers to inhibit corrosion of the magnetizable particles, and surfactants.

[0059] In another embodiment, a MR fluid that can etch while finishing is provided. The etching MR fluid includes magnetizable particles and abrasive particles suspended in a liquid vehicle including an etching agent. The etching agent is one that is capable of etching the material of the sheet of material and would be selected based on the material of the sheet of material. The liquid vehicle may further include a solvent for the etching agent. The liquid vehicle may further include stabilizers and surfactants. The liquid vehicle may be aqueous or non-aqueous, as described above. The magnetizable particles and abrasive particles are as described above for the non-etching MR fluid. The magnetizable particles may be coated or encapsulated, for example, with or in a protective material, as described above. The protective material, when used, is a material that is chemically and physically stable in the presence of the etching agent and other materials in the liquid vehicle. The protective material is also a material that does not react with the magnetizable particles. Suitable examples of protective materials are zirconia and silica.

[0060] In one embodiment, the etching agent included in the etching MR fluid has a pH less than or equal to 5. In one embodiment, the etching agent that has a pH less than or equal to 5 comprises an acid. In one embodiment, the etching agent is an acid. The acid may exist in liquid form or may be dissolved in a suitable solvent. Examples of suitable acids include, but are not limited to, hydrofluoric acid and sulfuric acid. The liquid vehicle may further include one or more stabilizers, e.g., a stabilizer to inhibit corrosion of the magnetizable particles. Stabilizers used in the liquid vehicle should be stable in the presence of the acid or, more generally, in the presence of the etching agent.

[0061] In another embodiment, the etching agent included in the etching MR fluid has a pH greater than or equal to 10. In one embodiment, the etching agent that has a pH greater than or equal to 10 comprised an alkali salt. In one embodiment, the etching agent is an alkali salt. Examples of such alkali salts include, but are not limited to, alkali hydroxides, e.g., potassium hydroxide, sodium hydroxide, and compounds containing alkali hydroxides. A detergent containing an alkali hydroxide may be used as the alkali salt in the liquid vehicle, for example. The liquid vehicle may include other materials besides alkali salts, such as surfactants and other materials that may be found in detergents. [0062] FIG. 7 illustrates a side schematic view of a magnetorheological finishing apparatus 145 configured to carry out MRF in accordance with aspects of the disclosure. As shown, MR fluid is deposited on a support surface in the form of an MRF ribbon 701. Typically, the support surface is a moving surface, but the support surface may also be a fixed surface. The support surface may have a variety of shapes, e.g., spherical, cylindrical, or flat. For illustration purposes, FIG. 7 shows a side view of the MRF ribbon 701 on a rotating wheel 703. In this case, the circumferential surface 705 of the rotating wheel 703 provides a moving cylindrical support surface for the MRF ribbon 701. A nozzle 707 is used to deliver the MRF ribbon 701 to one end of a segment the surface 705, and a nozzle 709 is used to collect the MRF ribbon 701 from another end of the segment of the surface 705. During the MRF, a magnet 711 applies a magnetic field to the MRF ribbon 701.

[0063] The applied magnetic field induces polarization on the magnetizable particles, causing the magnetizable particles to form chains or columnar structures that restrict flow. This increases the apparent viscosity of the MRF ribbon 701, changing the MRF ribbon 701 from a liquid state to a solid-like state. The edge portion 141a, 141b, 301a, 301b of the separated glass sheet 141 can be finished by contact with the stiffened MRF ribbon 701 and translating the edge portion of the separated glass sheet 141 along direction 713 relative to the stiffened MRF ribbon 701. The relative motion between the edge portion 141a, 141b, 301a, 301b and the MRF ribbon 701 is such that all the portions of the edge portion to be finished make contact with the stiffened MRF ribbon 701. In the case of glass sheets having a relatively thin average thickness in the ranges discussed above (e.g., from about 50 μιη to about 500 μιη) all portions of a segment of the edge portion 141a, 141b, 301a, 301b extending between the first face 405 and the second face 407 of the glass sheet 141 can simultaneously be finished and make contact with the stiffened MRF ribbon 701. As such, the entire edge portion 141a, 141b, 301a, 301b can shaped between the first face 405 and the second face 407 during a single magnetorheological finishing step. In one particular example, the single magnetorheological finishing step can comprise a single pass of each of the edge portions to be finished over the stiffened MRF ribbon 701. For instance, as shown in FIG. 7, finishing of the second edge portion 141b may be carried out with one pass of the separated glass sheet 141 relative to the magnetorheological finishing apparatus 145. As reciprocation is not necessary, finishing of each edge portion 141a, 141b, 301a, 301b of the glass sheet 141 can be carried out with reduced processing time.

[0064] In one embodiment, one or all of the edge portions 141a, 141b, 301a, 301b of the glass sheet 141 can be finished by immersing the respective edge portion into the stiffened MRF ribbon 701. Although the finishing process has been described in terms of finishing a single glass sheet using MRF, it should be noted that multiple glass sheets may be polished simultaneously in a single finishing process.

[0065] As shown in FIG. 8, the glass sheet can be positioned along a plane at a predetermined orientation within an angular range of from about + 45° to about - 45° with respect to a vertical axis. Indeed, as shown, the glass sheet 141 is positioned along a plane that is parallel with a vertical axis 801. In further examples, the glass sheet can be oriented at any orientation between an angle a and an angle β of about 45°.

[0066] MRF removes material from the surface being finished by shearing. This is in contrast to the fracturing mechanism associated with mechanical processes such as mechanical grinding. With this mechanism, MRF has an opportunity to remove material from the edge portion without inducing new fracture sites in the edge portion that could lower the strength of the edge portion. Simultaneously, MRF removes defects from the edge portion that results in an increase in the strength of the edge portion, i.e., from the first edge strength to the second edge strength. Moreover, the MRF ribbon 701, which is fluid -based, has the ability to conform to the shape of the edge portion, no matter the complexity, e.g., in terms of curvature or profile, of the edge portion, which leads to complete, high-quality finishing of the edge portion. MRF is governed by several parameters, e.g., the viscosity of the MR fluid, the rate at which the MR fluid is delivered to the moving surface, the speed of the moving surface, the intensity of the magnetic field, the height of the MRF ribbon, the depth to which the edge portion is immersed into the MRF ribbon, and the rate at which material is removed from the edge.

[0067] FIG. 9 is a first example flow chart illustrating example methods of the disclosure. All of the various methods of FIG. 9 begin at the start position 901 with the step 903 of providing a sheet of material with a first face and a second face. As discussed above, in one example, the sheet of material can comprise a glass sheet, such as the glass ribbon 106 or the separated glass sheet 141 with the first face 405 and the second face 407. Methods of the present disclosure can be used with a sheet of material (e.g., glass sheet comprising a glass ribbon, separated glass sheet, etc.) with a wide range of average thicknesses such as average thicknesses above 500 μιη. For example, the average thicknesses can be from greater than 500 μιη to about 2mm, such as from about 700 μιη to about 1.5mm, such as from about 900 μιη to about 1.2 mm, such as about 1.1 mm. In further examples, methods of the present disclosure can be used with a sheet of material including an average thickness "T" between the first face 405 and the second face 407 from about 50 μιη to about 500 μιη, such as material from about 50 μιη to about 300 μιη, such as from about 75 μιη to about 200 μιη, such as from about 75 μιη to about 150 μιη.

[0068] The step 903 of providing can occur at various relative times in the production process. For example, as shown in FIG. 1, the step 903 of providing can occur immediately after formation of the separated glass sheet 141. In further examples, the step 903 of providing can occur at a later time. For example, the separated glass sheet 141 may be transported to a different location wherein the sheet is subsequently provided during step 903 for processing. In further examples, the glass ribbon 106 may be coiled onto a storage roll. In such circumstances, the step of providing may occur prior to coiling the glass ribbon 106 onto the storage roll. In such examples, the edges of the ribbon may be finished with MRF prior to coiling onto the storage roll. In addition or alternatively, the coil of glass ribbon may be transferred to a different location for subsequent separation into desired separated glass sheets 141. In such examples, the step 903 of providing may occur as the glass ribbon is subsequently uncoiled for processing the separated glass sheets 141.

[0069] As indicated by arrow 905, the method can then optionally proceed from the step 903 of providing to a step 907 of separating the sheet of material to provide the edge portion 141a, 141b, 301a, 301b before a step 919 of finishing the edge portion of the sheet of material with MRF. As such, although not required, as shown in FIG. 9, the step 907 of separating can occur after the step 903 of providing.

[0070] The step 907 of separating may be carried out in a wide variety of ways. For example, separating may be carried out by mechanical separation, laser separation, ultrasonic separation or other separation techniques. The first separation device 205 illustrated in FIGS. 2 and 4 depict just one example laser separation device that may involve creating a mechanical flaw near an edge, then thermally run across the article using a laser 401 then separated using a stress gradient induced by the liquid cooling device 403, such as a water spray. The second separation device 207 illustrated in FIGS. 2 and 5 depict an example mechanical separation device. The second separation device 207 can include the scoring device 501 that may comprise a scoring wheel, water jets, or abrasive water jets. Then, as shown in FIG. 6, the sheet of material can be separated along the score lines, for example, by applying a force 603 to break away the edge member along the score line. Once separated, there may be a single sheet of material or a plurality of sheets of material. If a plurality of sheets of material are generated, one or all of the sheets of material may be processed.

[0071] As indicated by arrow 909, the method can then optionally proceed from the step 907 of separating to a step 911 of edging the sheet of material. If provided, the step 911 of edging the sheet of material can modify the shape and/or texture of the edge of the sheet of material by removing material from the edge. Any of a number of processes may be employed in the step 911 of edging. Examples include, but are not limited to, abrasive machining, abrasive jet machining, chemical etching, ultrasonic polishing, ultrasonic grinding, chemical-mechanical polishing. The step 911 of edging may include a single material removal process or a series or combination of material removal processes. For example, one example step 911 of edging may include a series of grinding steps, where the grinding parameters, such as the grit size of the grinding material, are altered for each step in the series to achieve a different edging result at the end of each step.

[0072] The step 911 of edging may include abrasive machining that may involve one or more and any combination of mechanical grinding, lapping, and polishing. These processes are mechanical in the sense that they involve contact between a solid tool and the surface being processed. Each of the grinding, lapping, and polishing may be accomplished in one or more steps. Grinding is a fixed-abrasive process, while lapping and polishing are loose-abrasive processes. Grinding may be accomplished using abrasive particles embedded in a metal or polymer bonded to a metal wheel. Alternatively, grinding may be accomplished using an expendable wheel made of an abrasive compound. In lapping, abrasive particles, typically suspended in a liquid medium, are disposed between a lap and an edge of a sheet of material. Relative motion between the lap and the edge of the sheet of material abrades material from the edge. In polishing, abrasive particles, typically suspended in a liquid medium, are applied to an edge of the sheet of material using a conformable soft pad or wheel. The conformable soft pad or wheel may be made of a polymeric material, e.g., butyl rubber, silicone, polyurethane, and natural rubber. Abrasives used in abrasive machining may be selected from, for example, alumina, silicon carbide, diamond, cubic boron nitride, and pumice.

[0073] As indicated by arrow 913, the method can then optionally proceed from the step 911 of edging to a step 915 chemical strengthening of the edge portion of the sheet of material (e.g., glass sheet). In one embodiment, the chemical-strengthening process is an ion- exchange process. In order to implement the ion-exchange process, the article provided in the step 903 of providing must be made of an ion-exchangeable material. Typically, ion- exchangeable materials are alkali-containing glasses with smaller alkali ions, such as Li⁺ and/or Na⁺, that can be exchanged for larger alkali ions, e.g., K⁺, during an ion-exchange process. Examples of suitable ion-exchangeable glasses are described in U.S. patent application Ser. Nos. 1 1/888,213, 12/277,573, 12/392,577, 12/393,241, and 12/537,393, U.S. Provisional Application Nos. 61/235,767 and 61/235,762 (all assigned to Corning Incorporated), the contents of which are incorporated herein by reference. These glasses can be ion-exchanged at relatively low temperatures and to a depth of at least 30 μιη.

[0074] An ion-exchange process is described in, for example, U.S. Pat. No. 5,674,790 (Araujo, Roger J.). The process typically occurs at an elevated temperature range that does not exceed the transition temperature of the glass. The process is carried out by immersing the glass in a molten bath comprising an alkali salt (typically a nitrate) with ions that are larger than that of the host alkali ions in the glass. The host alkali ions are exchanged for the larger alkali ions. For example, a glass containing Na⁺ may be immersed in a bath of molten potassium nitrate (KNO₃). The larger K⁺ present in the molten bath will replace the smaller Na⁺ in the glass. The presence of the larger alkali ions at sites formerly occupied by small alkali ions creates a compressive stress at or near the surface of the glass and tension in the interior of the glass. The glass is removed from the molten bath and cooled down after the ion-exchange process. The ion-exchange depth, i.e., the penetration depth of the invading larger alkali ions into the glass, is typically on the order of 20 μιη to 300 μιη, for example, 40 μιη to 300 μιη and is controlled by the glass composition and immersion time.

[0075] As indicated by arrow 917, the method can then optionally proceed from the step 915 of chemical strengthening of the edge portion of the sheet of material (e.g., glass sheet) to the step 919 of finishing the edge portion of the sheet of material with magnetorheological finishing (MRF). For example, as shown in FIG. 8 the separated glass sheet 141 may be moved along direction 713 during a single pass of the separated glass sheet 141 across the magnetorheological finishing apparatus 145 for each edge portion 141a, 141b, 301a, 301b.

[0076] As shown in FIG. 8, the step 903 of providing can position the sheet of material along a plane at a predetermined orientation wherein angles a and β are each 45° such that the predetermined orientation may be positioned within an angular range of from about + 45° to about - 45° with respect to the vertical axis 801 that can extend along the direction of gravity. In the example illustrated in FIG. 8, the separated glass sheet 141 is positioned vertically along a plane that includes the vertical axis 801 such that there is a 0° angle between the vertical axis 801 and the plane of the separated glass sheet 141. In a further example, the predetermined orientation of the sheet of material can be maintained during the step 919 of finishing the edge portion of the sheet of material with MRF.

[0077] As shown in some examples of FIG. 9, various the steps 907, 911, 915 of separating, edging and/or chemical strengthening can occur in any order and one or all of the steps may be omitted. For example, as indicated by arrow 921, the method may proceed from the step 903 of providing to the step 911 of edging; thereby omitting the step 907 of separating. Alternatively, as shown by arrow 923, the method may proceed from the step 903 of providing to the step 915 of chemical strengthening of the edge portion of the sheet of material (e.g., glass sheet); thereby omitting the steps 907, 911 of separating and edging. Still further, as shown by arrow 925, the method may proceed from the step 903 of providing directly to the step 919 of finishing the edge portion of the sheet of material with MRF; thereby omitting the steps 907, 911, 915 of separating, edging and chemical strengthening. As such, the method can consist essentially of the step 903 of providing and the step 919 of finishing the edge portion of the sheet of material with MRF.

[0078] As further shown in FIG. 9, after performing the step 907 of separating, if provided, the method may alternatively omit one or both of the subsequent steps 911, 915 of edging and/or chemical strengthening. For example, as shown by arrow 927, the method may proceed from the step 907 of separating to the step 915 of chemical-strengthening; thereby omitting the step 911 of edging. In another example, as shown by arrow 929, the method may proceed from the step 907 of separating to the step 919 of finishing the edge portion of the sheet material with MRF; thereby omitting both steps 911, 915 of edging and chemical- strengthening may be omitted.

[0079] FIG. 10 illustrates a second example flow chart illustrating further example methods of the disclosure. As shown, the method may begin at the start position 1001 and proceed in a wide variety of paths. As shown in some examples of FIG. 10 and discussed below, various steps 1005, 1009, 1013 of separating, edging and/or chemical strengthening can occur in any order and one or all of the steps may be omitted.

[0080] For example, as indicated by arrow 1003, the method may continue from the start position 1001 to the step 1005 of separating. Alternatively, as indicated by arrow 1007, the method may continue from the start position 1001 to the step 1009 of edging; thereby omitting the step 1005 of separating. Still further, as indicated by arrow 1011, the method may continue from the start position 1001 to the step 1013 of chemically strengthening; thereby omitting the steps 1005, 1009 of separating and edging. In another example, as indicated by arrow 1015 the method may continue from the start position 1001 to the step 1017 of providing; thereby omitting all three steps 1005, 1009, 1013 of separating, edging and chemically strengthening. In further examples, as indicated by arrows 1008, 1012, 1016, the method may sequentially proceed from the step 1005 of separating, to the step 1009 of edging, to the step 1013 of chemically strengthening, and then to the step 1017 of providing. As such, any of the steps of separating, edging, and/or chemical strengthening may occur before the step of providing. As indicated by arrow 1025, the method can then proceed directly from the step 1017 of providing to the step 1027 of finishing the edge portion of the sheet material with MRF.

[0081] Moreover, the step 1005 of separating may be present without the steps 1009, 1013 of edging and/or chemical strengthening. Indeed, as indicated by arrow 1019, the method may proceed from the step 1005 of separating to the step 1013 of chemical strengthening; thereby omitting the step 1009 of edging. As further indicated by arrow 1021, the method may proceed from the step 1005 of separating to the step 1017 of providing; thereby omitting the steps 1009, 1013 of edging and chemical strengthening.

[0082] Still further, the step 1009 of edging may be present without the step 1013 of chemical strengthening. For example, as indicated by arrow 1023, the method may proceed from the step 1009 of edging directly to the step 1017 of providing; thereby omitting the step 1013 of chemical strengthening.

[0083] As shown in FIG. 9 some or all of the steps 907, 911, 915 of separating, edging and/or chemical strengthening may occur after the step 903 of providing. In further examples, some or all of the steps 907, 911, 915 may occur before the step of providing. For example, FIG. 10 demonstrates that all of the steps 1005, 1009, 1013 of separating, edging and chemical strengthening may occur before the step 1017 of providing. Although not shown, in further examples any combination of steps 1005, 1009, 1013 may occur before and/or after the step of providing. For example, one or two of the steps of separating, edging and chemical strengthening may occur before the step of providing while the remaining step(s) occur after the step of providing.

[0084] In one example, of methods of finishing an edge portion 141a, 141b, 301a, 301b of a glass sheet (e.g., glass ribbon, separated glass sheet, etc.) is provided. The glass sheet 141 can include the first face 405 and the second face 407. The edge portion can extend along a peripheral portion of the glass sheet between the first face and the second face. The method can consist essentially of a single step 919, 1027 of finishing the edge portion 141a, 141b, 301a, 301b of the glass sheet with MRF. In such examples, the entire edge portion may be shaped between the first face 405 and the second face 407 during the single MRF step.

[0085] In another example, methods of finishing an edge portion 141a, 141b, 301a, 301b of a glass sheet (e.g., glass ribbon, separated glass sheet, etc.) consists essentially of the step 903, 1017 of providing and the step 919, 1027 of finishing the edge portion of the glass sheet with MRF. For instance, the step 903, 1017 of providing can provide the glass sheet with the first face 405 and the second face 407, wherein an average thickness of the glass sheet between the first face and the second face is from about 50 μιη to about 500 μιη. In one example, during step 919, 1027, the entire edge portion is shaped between the first face and the second face during a single magnetorheological finishing step.

[0086] FIG. 11 illustrates an enlarged view of an edge portion 1101 of a separated glass sheet 141 having a thickness "T" of about 100 μιη between the first face 405 and the second face 407 observed after separating the glass sheet but prior to MRF of the edge portion. As shown, the edge portion 1101 includes undesirable sharp edge portions 1103 that are vulnerable to cracking of the glass sheet. FIG. 12 shows the same observed enlarged view of the edge portion 1101 after a 6 minute MRF step as set forth by the disclosure. As shown, the undesired sharp edge portions 1103 are removed and is left with a smooth surface 1201 that has a smooth shape along the entire edge portion from the first face 405 to the second face 407. Indeed, as shown, the smooth surface 1201 has a rounded and convex shape extending from the first face 405 to the second face 407 with relatively little material removed.

[0087] The rounded edge profile illustrated in FIG. 12 of thin glass (e.g., 100 μιη) can facilitate manufacture of a variety of products including thin glass for light weight and portability. Using a finishing step including MRF can provide a single step shaped edge for laser and mechanical separated thin glass. Using MRF as the finishing step can be uniquely beneficial for thin glass since the low volume removal from the edges, demonstrated by comparing the slightly different lengths from FIGS. 11 and 12, can be accomplished with reasonable cycle times.

[0088] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the claimed invention.

Claims

CLAIMS What is claimed is:

1. A method of finishing a sheet of material comprising the steps of:

(I) providing a sheet of material with a first face and a second face, wherein an average thickness of the sheet of material between the first face and the second face is from about 50 μιη to about 500 μιη; and

(II) finishing an edge portion of the sheet of material with magnetorheological finishing.

2. The method of claim I, wherein step (I) provides the sheet of material as a glass sheet.

3. The method of claim I, wherein step (I) provides the average thickness of the sheet of material from about 50 μιη to about 300 μιη.

4. The method of claim 3, wherein step (I) provides the average thickness of the sheet of material from about 75 μιη to about 200 μιη.

5. The method of claim 4, wherein step (I) provides the average thickness of the sheet of material from about 75 μιη to about 150 μιη.

6. The method of claim 1 , wherein step (I) provides the sheet of material positioned along a plane at a predetermined orientation within an angular range of from about + 45° to about - 45° with respect to a vertical axis.

7. The method of claim 6, wherein the predetermined orientation of the sheet of material is maintained during step (II).

8. The method of claim 1, wherein step (I) provides the edge portion extending along a peripheral portion of the sheet of material between the first face and the second face.

9. The method of claim 1, further comprising a step of strengthening the edge portion before step (II).

10. The method of claim 1 , further comprising a step of separating the sheet of material to provide the edge portion before step (II).

1 1. The method of claim 10, wherein the step of separating occurs after step (I).

12. The method of claim 10, further comprising a step of strengthening the edge portion after the step of separating and before step (II).

13. The method of claim 1, further comprising a step of edging the sheet of material to provide the edge portion before step (II).

14. The method of claim 13, wherein the step of edging occurs after step (I).

15. The method of claim 13, further comprising a step of separating the sheet of material before the step of edging the sheet of material.

16. The method of claim 13, further comprising a step of strengthening the edge portion after the step of edging and before step (II).

17. A method of finishing an edge portion of a glass sheet having a first face and a second face with the edge portion extending along a peripheral portion of the glass sheet between the first face and the second face, the method consisting essentially of a single step of:

finishing the edge portion of the glass sheet with magnetorheo logical finishing such that the entire edge portion is shaped between the first face and the second face during the a single magnetorheological finishing step.

18. A method of finishing an edge portion of a glass sheet consisting essentially of the steps of:

(I) providing a glass sheet with a first face and a second face, wherein an average thickness of the glass sheet between the first face and the second face is from about 50 μιη to about 500 μιη; and

(II) finishing an edge portion of the glass sheet with magnetorheological finishing.

19. The method of claim 18, wherein, during step (II), the entire edge portion is shaped between the first face and the second face during a single magnetorheological finishing step.

20. The method of claim 18, wherein step (I) provides the average thickness of the glass sheet from about 75 μιη to about 150 μιη.