US20130225049A1 - Methods of Finishing a Sheet of Material With Magnetorheological Finishing - Google Patents

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 50 μm 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

• This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/604,863 filed on Feb. 29, 2012 the content of which is relied upon and incorporated herein by reference in its entirety.
TECHNICAL FIELD
• 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
• 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
• 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.
• 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 μm to about 500 μm. The method further comprises the step (II) of finishing an edge portion of the sheet of material with magnetorheological finishing.
• In one example of the aspect, step (I) provides the sheet of material as a glass sheet.
• In another example of the aspect, step (I) provides the average thickness of the sheet of material from about 50 μm to about 300 μm.
• In still another example of the aspect, step (I) provides the average thickness of the sheet of material from about 75 μm to about 200 μm.
• In yet another example of the aspect, step (I) provides the average thickness of the sheet of material from about 75 μm to about 150 μm.
• 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.
• In another example of the aspect, the predetermined orientation of the sheet of material is maintained during step (II).
• 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.
• In another example of the aspect, the method includes a step of strengthening the edge portion before step (II).
• 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).
• In still a further example of the aspect, the step of separating occurs after step (I).
• 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 (II).
• 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).
• In a further example of the aspect, the step of edging occurs after step (I).
• 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.
• 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).
• 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 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.
• 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 μm to about 500 μm; and (II) finishing an edge portion of the glass sheet with magnetorheological finishing.
• 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.
• In another example of the aspect, step (I) provides the average thickness of the glass sheet from about 75 μm to about 150 μm.
BRIEF DESCRIPTION OF THE DRAWINGS
• These and other aspects are better understood when the following detailed description is read with reference to the accompanying drawings, in which:
• FIG. 1 illustrates a glass manufacturing apparatus configured to produce a glass sheet that may be used with methods in accordance with the disclosure;
• 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;
• FIG. 3 illustrates edge members after separating from the remaining portion of the glass sheet with the methods of separating illustrated inFIG. 2;
• FIG. 4 illustrates a side view of the first separation device ofFIG. 2;
• FIG. 5 illustrates a side view of the second separation device ofFIG. 2;
• FIG. 6 illustrates a method step of breaking away the edge member after scoring with the second separation device ofFIG. 5;
• 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;
• FIG. 8 is a front view of the separated glass sheet and magnetorheological finishing apparatus ofFIG. 7;
• FIG. 9 is a first example flow chart illustrating example methods of the disclosure;
• FIG. 10 is a second example flow chart illustrated further example methods of the disclosure;
• 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 μm between a first face and a second face of the glass sheet; and
• FIG. 12 is an enlarged view of the edge portion ofFIG. 11 after magnetorheological finishing.
DETAILED DESCRIPTION
• 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.
• 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.
• The glass sheet may be formed by a wide range of techniques. As shown inFIG. 1, there is shown a schematic view of an exemplaryglass manufacturing apparatus101 that may be used in accordance with aspects of the disclosure. The exemplaryglass manufacturing apparatus101 is illustrated as a down draw fusion apparatus although other forming apparatus may be used in further examples.
• Theglass manufacturing apparatus101 can include amelting vessel103, afining vessel105, amixing vessel107, adelivery vessel109, a formingdevice111, apull roll device113 and aseparating device115.
• Themelting vessel103 is where the glass batch materials are introduced as shown byarrow117 and melted to formmolten glass119. Thefining vessel105 has a high temperature processing area that receives the molten glass119 (not shown at this point) from themelting vessel103 and in which bubbles are removed from themolten glass119. Thefining vessel105 is connected to themixing vessel107 by a finer to stirchamber connecting tube121. Themixing vessel107 is connected to thedelivery vessel109 by a stir chamber to bowl connectingtube123. Thedelivery vessel109 delivers themolten glass119 through adowncomer125 to aninlet127 and into the formingdevice111.
• Various forming devices may be used in accordance with aspects of the disclosure. For example, as shown inFIG. 1, the formingdevice111 includes anopening129 that receives themolten glass119 which flows into atrough131. Themolten glass119 from thetrough131 then overflows and runs down two sides132 (one side shown inFIG. 1) before fusing together at aroot133 of the formingdevice111. Theroot133 is where the twosides132 come together and where the two overflow walls ofmolten glass119 flowing over each of the twosides132 fuse together as theglass ribbon106 is drawn downward off theroot133.
• A portion of theglass ribbon106 is drawn off theroot133 into aviscous zone135 wherein theglass ribbon106 begins thinning to a final thickness. The portion of theglass ribbon106 is then drawn from theviscous zone135 into asetting zone137. In thesetting zone137, the portion of theglass ribbon106 is set from a viscous state to an elastic state with the desired profile. The portion of theglass ribbon106 is then drawn from thesetting zone137 to anelastic zone139. Once in theelastic zone139, theglass ribbon106 may be deformed, within limits, without permanently changing the profile of theglass ribbon106.
• After the portion of theglass ribbon106 enters theelastic zone139, theseparating device115 may be provided to sequentially separate a plurality of separatedglass sheets141 from theglass ribbon106 over a period of time. Theseparating device115 may include the illustrated traveling anvil machine although further separating devices may be provided in further examples.
• As further illustrated inFIG. 1, theglass manufacturing apparatus101 may be provided withsupport devices143, such as a suction cup apparatus, air bearing, or other support device, to help support the glass sheet, such as theglass ribbon106 and/or the separatedglass sheets141. 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., theglass ribbon106, separatedglass sheets141 that are separated from the glass ribbon, or glass sheets formed by other techniques).
• As such, while various methods of the disclosure are described with respect to the separatedglass sheets141, it is understood that the methods of the disclosure may be carried out with other forms of the glass sheets (e.g., theglass ribbon106 or glass sheets formed with other techniques).
• As discussed above, the glass sheet can be initially formed as aglass ribbon106 by way of the example glass manufacturing apparatus, although glass sheets may be formed by other techniques. Aseparating device115, such as the illustrated traveling anvil machine can be used to separate theglass ribbon106 into the separatedglass sheets141. As such, the traveling anvil machine may create afirst edge portion141aand asecond edge portion141b,wherein the length of the separatedglass ribbon141 is defined between the first andsecond edge portions141a,141b.It will be appreciated that in further examples, the width of the separatedglass ribbon141 can be defined between the first andsecond edge portions141a,141b.As further shown inFIG. 1, theglass manufacturing apparatus101 may include amagnetorheological finishing apparatus145 that may be part of theglass manufacturing apparatus101 although themagnetorheological finishing apparatus145 may be provided at a downstream processing location from theglass manufacturing apparatus101 in further examples. In such examples, thesupport devices143 may be operated to transport the separatedglass sheet141 such that the first and/orsecond edge portions141a,141bare finished with themagnetorheological finishing apparatus145. In some examples, thesupport devices143 can support theglass ribbon106 and then continue to support the separatedglass sheet141 throughout the entire separating and finishing process techniques illustrated inFIGS. 2-8 described more fully below.
• As shown inFIGS. 2 and 3, the first andsecond edge members201,203 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 theglass manufacturing apparatus101. 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 inFIGS. 2 and 3, themagnetorheological finishing apparatus145 may be provided at the station where the edge members are removed. For example themagnetorheological finishing apparatus145 may be used to finish one or both of the first andsecond edge portion141a,141bwhile the edge members are being removed as illustrated inFIG. 2. In addition or alternatively, themagnetorheological finishing apparatus145 may be used to finish one or both of the second andthird edge portions301a,301bshown inFIG. 3.
• 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 separatedglass sheet141.FIGS. 2 and 4 illustrate just one glass separation technique that may include use of afirst separation device205 that can include alaser401 configured to heat a surface of the separatedglass sheet141 and aliquid cooling device403 configured to propagate a crack to separate thefirst edge member201 from the remaining portion of the separatedglass sheet141.
• FIGS. 2,5 and6 illustrated another example of asecond separation device207 comprising ascoring device501 that can create a score line209 along a separation path. Once formation of the score line is complete, apivot member601 can be applied on the opposite side of the score line209 and aforce603 can be applied to break away thesecond edge member203 from the remaining portion of the separatedglass sheet141.
• As shown inFIG. 3, once the first andsecond edge members201,203 are removed, the separatedglass sheet141 includes athird edge portion301aand afourth edge portion301b, wherein the width of the separatedglass ribbon141 is defined between the third andfourth edge portions301a,301b.It will be appreciated that in further examples, the length of the separatedglass ribbon141 can be defined between the third andfourth edge portions301a,301b.
• The traveling anvil machine (e.g., see theseparation device115 shown inFIG. 1), thefirst separation device205 and thesecond separation device207 are mere examples of various possible separation devices that may be used to separate the glass sheets. Regardless of the techniques used, eachedge portion141a,141b,301a,301bmay include undesirable rough/sharp edge portions that are vulnerable to cracking of the glass sheet.
• 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 μm. For example, the average thicknesses can be from greater than 500 μm to about 2 mm, such as from about 700 μm to about 1.5 mm, such as from about 900 μm to about 1.2 mm, such as about 1.1 mm.
• 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 inFIG. 4, the relatively thinseparated glass sheets141 can have average thicknesses “T” between afirst face405 and asecond face407, wherein an average thickness of the glass sheet between thefirst face405 and thesecond face407 is less than or equal to about 500 μm, such as less than or equal to about 400 μm, such as less than or equal to about 300 μm, such as less than or equal to about 200 μm, such as less than or equal to about 100 μm, such as less than or equal to about 75 μm. In one example, the average thickness “T” between thefirst face405 and thesecond face407 is from about 50 μm to about 500 μm, such as from about 50 μm to about 400 μm, such as from about 50 μm to about 300 μm, such as from about 50 μm to about 200 μm, such as from about 50 μm to about 100 μm, such as from about 50 μm to about 75 μm, such as from about 75 μm to about 500 μm, such as from about 75 μm to about 400 μm, such as from about 75 μm to about 300 μm, such as from about 75 μm to about 200 μm, such as from about 75 μm to about 150 μm, such as from about 75 μm to about 100 μm, such as from about 100 μm to about 500 μm, such as from about 100 μm to about 400 μm, such as from about 100 μm to about 300 μm, such as from about 100 μm to about 200 μm. Providing glass sheets having a thin average thickness “T” can be desirable to enhance performance characteristics.
• Finishing theedge portions141a,141b,301a,301bcan 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 Ser. No. 13/112,498 filed May 20, 2011 and/or U.S. patent application Ser. No. 13/169,499 filed Jun. 27, 2011 may be incorporated in accordance with aspects of the disclosure. U.S. patent application Ser. No. 13/112,498 filed May 20, 2011 and U.S. patent application Ser. No. 13/169,499 filed Jun. 27, 2011 are each herein incorporated by reference in its entirety.
• 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 separatedglass sheet141.
• 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 μm to 100 μm or greater, for example, 1 μm to 150 μm, for example, 5 μm to 150 μm, for example, 5 μm to 100 μm, for example, 5 μm to 50 μm, for example, 5 μm to 25 μm, for example, 10 μm to 25 μm and the sizes of the abrasive particles may be in a range from 15 nm to 10 μm. 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.
• 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.
• 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.
• 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.
• FIG. 7 illustrates a side schematic view of amagnetorheological finishing apparatus145 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 anMRF ribbon701. 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 theMRF ribbon701 on arotating wheel703. In this case, thecircumferential surface705 of therotating wheel703 provides a moving cylindrical support surface for theMRF ribbon701. Anozzle707 is used to deliver theMRF ribbon701 to one end of a segment thesurface705, and anozzle709 is used to collect theMRF ribbon701 from another end of the segment of thesurface705. During the MRF, amagnet711 applies a magnetic field to theMRF ribbon701.
• 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 theMRF ribbon701, changing theMRF ribbon701 from a liquid state to a solid-like state. Theedge portion141a,141b,301a,301bof the separatedglass sheet141 can be finished by contact with the stiffenedMRF ribbon701 and translating the edge portion of the separatedglass sheet141 alongdirection713 relative to the stiffenedMRF ribbon701. The relative motion between theedge portion141a,141b,301a,301band theMRF ribbon701 is such that all the portions of the edge portion to be finished make contact with the stiffenedMRF ribbon701. In the case of glass sheets having a relatively thin average thickness in the ranges discussed above (e.g., from about 50 μm to about 500 μm) all portions of a segment of theedge portion141a,141b,301a,301bextending between thefirst face405 and thesecond face407 of theglass sheet141 can simultaneously be finished and make contact with the stiffenedMRF ribbon701. As such, theentire edge portion141a,141b,301a,301bcan shaped between thefirst face405 and thesecond face407 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 stiffenedMRF ribbon701. For instance, as shown inFIG. 7, finishing of thesecond edge portion141bmay be carried out with one pass of the separatedglass sheet141 relative to themagnetorheological finishing apparatus145. As reciprocation is not necessary, finishing of eachedge portion141a,141b,301a,301bof theglass sheet141 can be carried out with reduced processing time.
• In one embodiment, one or all of theedge portions141a,141b,301a,301bof theglass sheet141 can be finished by immersing the respective edge portion into the stiffenedMRF ribbon701. 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.
• As shown inFIG. 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, theglass sheet141 is positioned along a plane that is parallel with a vertical axis801. In further examples, the glass sheet can be oriented at any orientation between an angle α and an angle β of about 45°.
• 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, theMRF ribbon701, 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.
• FIG. 9 is a first example flow chart illustrating example methods of the disclosure. All of the various methods ofFIG. 9 begin at thestart position901 with thestep903 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 theglass ribbon106 or the separatedglass sheet141 with thefirst face405 and thesecond face407. 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 μm. For example, the average thicknesses can be from greater than 500 μm to about 2 mm, such as from about 700 μm to about 1.5 mm, such as from about 900 μm 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 thefirst face405 and thesecond face407 from about 50 μm to about 500 μm, such as material from about 50 μm to about 300 μm, such as from about 75 μm to about 200 μm, such as from about 75 μm to about 150 μm.
• Thestep903 of providing can occur at various relative times in the production process. For example, as shown inFIG. 1, thestep903 of providing can occur immediately after formation of the separatedglass sheet141. In further examples, thestep903 of providing can occur at a later time. For example, the separatedglass sheet141 may be transported to a different location wherein the sheet is subsequently provided duringstep903 for processing. In further examples, theglass ribbon106 may be coiled onto a storage roll. In such circumstances, the step of providing may occur prior to coiling theglass ribbon106 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 separatedglass sheets141. In such examples, thestep903 of providing may occur as the glass ribbon is subsequently uncoiled for processing the separatedglass sheets141.
• As indicated byarrow905, the method can then optionally proceed from thestep903 of providing to astep907 of separating the sheet of material to provide theedge portion141a,141b,301a,301bbefore astep919 of finishing the edge portion of the sheet of material with MRF. As such, although not required, as shown inFIG. 9, thestep907 of separating can occur after thestep903 of providing.
• Thestep907 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. Thefirst separation device205 illustrated inFIGS. 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 alaser401 then separated using a stress gradient induced by theliquid cooling device403, such as a water spray. Thesecond separation device207 illustrated inFIGS. 2 and 5 depict an example mechanical separation device. Thesecond separation device207 can include thescoring device501 that may comprise a scoring wheel, water jets, or abrasive water jets. Then, as shown inFIG. 6, the sheet of material can be separated along the score lines, for example, by applying aforce603 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.
• As indicated byarrow909, the method can then optionally proceed from thestep907 of separating to astep911 of edging the sheet of material. If provided, thestep911 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 thestep911 of edging. Examples include, but are not limited to, abrasive machining, abrasive jet machining, chemical etching, ultrasonic polishing, ultrasonic grinding, chemical-mechanical polishing. Thestep911 of edging may include a single material removal process or a series or combination of material removal processes. For example, oneexample step911 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.
• Thestep911 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.
• As indicated byarrow913, the method can then optionally proceed from thestep911 of edging to astep915 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 thestep903 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. 11/888,213, 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 μm.
• 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 μm to 300 μm, for example, 40 μm to 300 μm and is controlled by the glass composition and immersion time.
• As indicated byarrow917, the method can then optionally proceed from thestep915 of chemical strengthening of the edge portion of the sheet of material (e.g., glass sheet) to thestep919 of finishing the edge portion of the sheet of material with magnetorheological finishing (MRF). For example, as shown inFIG. 8 the separatedglass sheet141 may be moved alongdirection713 during a single pass of the separatedglass sheet141 across themagnetorheological finishing apparatus145 for eachedge portion141a,141b,301a,301b.
• As shown inFIG. 8, thestep903 of providing can position the sheet of material along a plane at a predetermined orientation wherein angles α 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 axis801 that can extend along the direction of gravity. In the example illustrated inFIG. 8, the separatedglass sheet141 is positioned vertically along a plane that includes the vertical axis 801 such that there is a 0° angle between the vertical axis801 and the plane of the separatedglass sheet141. In a further example, the predetermined orientation of the sheet of material can be maintained during thestep919 of finishing the edge portion of the sheet of material with MRF.
• As shown in some examples ofFIG. 9, various thesteps907,911,915 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 byarrow921, the method may proceed from thestep903 of providing to thestep911 of edging; thereby omitting thestep907 of separating. Alternatively, as shown byarrow923, the method may proceed from thestep903 of providing to thestep915 of chemical strengthening of the edge portion of the sheet of material (e.g., glass sheet); thereby omitting thesteps907,911 of separating and edging. Still further, as shown byarrow925, the method may proceed from thestep903 of providing directly to thestep919 of finishing the edge portion of the sheet of material with MRF; thereby omitting thesteps907,911,915 of separating, edging and chemical strengthening. As such, the method can consist essentially of thestep903 of providing and thestep919 of finishing the edge portion of the sheet of material with MRF.
• As further shown inFIG. 9, after performing thestep907 of separating, if provided, the method may alternatively omit one or both of thesubsequent steps911,915 of edging and/or chemical strengthening. For example, as shown byarrow927, the method may proceed from thestep907 of separating to thestep915 of chemical-strengthening; thereby omitting thestep911 of edging. In another example, as shown byarrow929, the method may proceed from thestep907 of separating to thestep919 of finishing the edge portion of the sheet material with MRF; thereby omitting bothsteps911,915 of edging and chemical-strengthening may be omitted.
• FIG. 10 illustrates a second example flow chart illustrating further example methods of the disclosure. As shown, the method may begin at thestart position1001 and proceed in a wide variety of paths. As shown in some examples ofFIG. 10 and discussed below,various steps1005,1009,1013 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 byarrow1003, the method may continue from thestart position1001 to thestep1005 of separating. Alternatively, as indicated byarrow1007, the method may continue from thestart position1001 to thestep1009 of edging; thereby omitting thestep1005 of separating. Still further, as indicated byarrow1011, the method may continue from thestart position1001 to thestep1013 of chemically strengthening; thereby omitting thesteps1005,1009 of separating and edging. In another example, as indicated byarrow1015 the method may continue from thestart position1001 to thestep1017 of providing; thereby omitting all threesteps1005,1009,1013 of separating, edging and chemically strengthening. In further examples, as indicated byarrows1008,1012,1016, the method may sequentially proceed from thestep1005 of separating, to thestep1009 of edging, to thestep1013 of chemically strengthening, and then to thestep1017 of providing. As such, any of the steps of separating, edging, and/or chemical strengthening may occur before the step of providing. As indicated byarrow1025, the method can then proceed directly from thestep1017 of providing to thestep1027 of finishing the edge portion of the sheet material with MRF.
• Moreover, thestep1005 of separating may be present without thesteps1009,1013 of edging and/or chemical strengthening. Indeed, as indicated byarrow1019, the method may proceed from thestep1005 of separating to thestep1013 of chemical strengthening; thereby omitting thestep1009 of edging. As further indicated byarrow1021, the method may proceed from thestep1005 of separating to thestep1017 of providing; thereby omitting thesteps1009,1013 of edging and chemical strengthening.
• Still further, thestep1009 of edging may be present without thestep1013 of chemical strengthening. For example, as indicated byarrow1023, the method may proceed from thestep1009 of edging directly to thestep1017 of providing; thereby omitting thestep1013 of chemical strengthening.
• As shown inFIG. 9 some or all of thesteps907,911,915 of separating, edging and/or chemical strengthening may occur after thestep903 of providing. In further examples, some or all of thesteps907,911,915 may occur before the step of providing. For example,FIG. 10 demonstrates that all of thesteps1005,1009,1013 of separating, edging and chemical strengthening may occur before thestep1017 of providing. Although not shown, in further examples any combination ofsteps1005,1009,1013 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.
• In one example, of methods of finishing anedge portion141a,141b,301a,301bof a glass sheet (e.g., glass ribbon, separated glass sheet, etc.) is provided. Theglass sheet141 can include thefirst face405 and thesecond face407. 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 asingle step919,1027 of finishing theedge portion141a,141b,301a,301bof the glass sheet with MRF. In such examples, the entire edge portion may be shaped between thefirst face405 and thesecond face407 during the single MRF step.
• In another example, methods of finishing anedge portion141a,141b,301a,301bof a glass sheet (e.g., glass ribbon, separated glass sheet, etc.) consists essentially of thestep903,1017 of providing and thestep919,1027 of finishing the edge portion of the glass sheet with MRF. For instance, thestep903,1017 of providing can provide the glass sheet with thefirst face405 and thesecond face407, wherein an average thickness of the glass sheet between the first face and the second face is from about 50 μm to about 500 μm. In one example, duringstep919,1027, the entire edge portion is shaped between the first face and the second face during a single magnetorheological finishing step.
• FIG. 11 illustrates an enlarged view of anedge portion1101 of a separatedglass sheet141 having a thickness “T” of about 100 μm between thefirst face405 and thesecond face407 observed after separating the glass sheet but prior to MRF of the edge portion. As shown, theedge portion1101 includes undesirablesharp edge portions1103 that are vulnerable to cracking of the glass sheet.FIG. 12 shows the same observed enlarged view of theedge portion1101 after a 6 minute MRF step as set forth by the disclosure. As shown, the undesiredsharp edge portions1103 are removed and is left with asmooth surface1201 that has a smooth shape along the entire edge portion from thefirst face405 to thesecond face407. Indeed, as shown, thesmooth surface1201 has a rounded and convex shape extending from thefirst face405 to thesecond face407 with relatively little material removed.
• The rounded edge profile illustrated inFIG. 12 of thin glass (e.g., 100 μm) 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 fromFIGS. 11 and 12, can be accomplished with reasonable cycle times.
• 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 (20)

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 μm to about 500 μm; and

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

2. The method ofclaim 1, wherein step (I) provides the sheet of material as a glass sheet.

3. The method ofclaim 1, wherein step (I) provides the average thickness of the sheet of material from about 50 μm to about 300 μm.

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

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

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

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

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

11. The method ofclaim 10, wherein the step of separating occurs after step (I).

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

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

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

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

16. The method ofclaim 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 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.

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 μm to about 500 μm; and

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

19. The method ofclaim 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 ofclaim 18, wherein step (I) provides the average thickness of the glass sheet from about 75 μm to about 150 μm.

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