Patent Publication Number: US-2016221148-A1

Title: Glass sleeve internal polishing

Description:
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 62/109857 filed on Jan. 30, 2015 the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The disclosure relates to systems and methods for polishing internal surfaces of a hollow structure, and more particularly to a system, such as a magnetic polisher, for polishing an internal surface of a glass sleeve, and methods for polishing a glass sleeve to produce a three-dimensional formed glass cover for a handheld smart phone or other consumer electronic device. The glass cover optionally may be sleeve-shaped. 
     SUMMARY 
     The present disclosure relates, in various embodiments, generally to a magnetic polisher for polishing internal surface of glass sleeve. The magnetic polisher may comprise at least one rotatable driver and at least one rotatable polishing tool. The at least one rotatable driver may comprise driver magnetic material. The at least one rotatable polishing tool may comprise tool magnetic material and a first polishing surface. At least one of the driver magnetic material and the tool magnetic material may be a magnet. The driver and polishing tool may be configured to be magnetically coupled with a workpiece. The workpiece may have at least a first internal surface to be polished. The workpiece may be located between the first polishing surface and the driver. The rotation of the driver about an axis may cause rotation of the first polishing surface against the first internal surface. 
     The present disclosure relates, in various embodiments, to a method for polishing a glass sleeve with a flattened portion. The method may be useful in manufacturing a sleeve-like structure. The method is carried out by providing a glass sleeve. The glass sleeve may have at least one substantially flat internal surface extending along a longitudinal axis and an internal opening extending along the longitudinal axis enclosing a space. A rotatable polishing tool may be introduced to polish the glass sleeve. The rotatable polishing tool may include a magnetic material and a first polishing surface which may be brought into the space within the glass sleeve. The first polishing surface may be brought into contact with the substantially flat internal surface. A rotatable driver may be introduced. The rotatable driver may include a magnetic material outside the glass sleeve. The tool magnetic material may be a magnet so that the driver may magnetically couple with the polishing tool. The driver may be rotated, causing the polishing tool to rotate. 
     Additional features and advantages of the present disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       The following is a description of the figures in the accompanying drawings. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity or conciseness. 
         FIG. 1  is a schematic side view of a magnetic polisher in use according to an embodiment; 
         FIG. 2  is a schematic side view of a magnetic polisher in use according to another embodiment; 
         FIG. 3  is a top view of a rotatable polishing tool in use according to the embodiment of  FIG. 2 ; 
         FIG. 4  is a perspective view of a polishing pad usable, for example, in the embodiments of any Figure; 
         FIG. 5  is a schematic side view of a magnetic polisher usable, for example, in the embodiments of any Figure; 
         FIG. 6  is a schematic side view of another type of magnetic polisher usable, for example, in the embodiments of  FIGS. 1-4 and 7 ; and 
         FIG. 7  is a flow chart illustrating a method for polishing a glass sleeve according to one embodiment. 
       The following reference characters are used in this specification: 
       
         
           
             
                 
                 
               
                 
                     
                 
               
              
                 
                   100 
                   Magnetic polisher 
                 
                 
                   102 
                   Axis 
                 
                 
                   110 
                   Rotatable driver 
                 
                 
                   120 
                   Rotatable polishing tool 
                 
                 
                   122 
                   Polishing surface 
                 
                 
                   130 
                   workpiece 
                 
                 
                   132 
                   First internal surface 
                 
                 
                   140 
                   Driving motor 
                 
                 
                   140 
                   Variable spacer 
                 
                 
                   150 
                   Translation stage 
                 
                 
                   160 
                   Magnet for driver 
                 
                 
                   170 
                   Magnet for polishing tool 
                 
                 
                   180 
                   Polishing pad 
                 
                 
                   210 
                   Shaft 
                 
                 
                   410 
                   radial slots 
                 
                 
                   500 
                   Driving pad 
                 
                 
                   510 
                   Driver polishing surface 
                 
                 
                   520 
                   External surface 
                 
                 
                   600 
                   Internal spring 
                 
                 
                   610 
                   Second polishing surface 
                 
                 
                   620 
                   second internal surface 
                 
                 
                   630 
                   Second non-magnetic polishing pad 
                 
                 
                   640 
                   Polishing paper 
                 
                 
                   700 
                   Method for polishing a glass sleeve 
                 
                 
                   710 
                   First step of the method 
                 
                 
                   720 
                   Second step of the method 
                 
                 
                   730 
                   Third step of the method 
                 
                 
                   740 
                   Fourth step of the method 
                 
                 
                   750 
                   Fifth step of the method 
                 
                 
                     
                 
              
             
           
         
       
       The foregoing summary, as well as the following detailed description of certain inventive techniques, will be better understood when read in conjunction with the figures. It should be understood that the claims are not limited to the arrangements and instrumentalities shown in the figures. Furthermore, the appearance shown in the figures is one of many ornamental appearances that can be employed to achieve the stated functions of the apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure can be understood more readily by reference to the following detailed description, drawings, examples, and claims, and the previous and following description. However, before the present compositions, articles, devices, and methods are disclosed and described, it is to be understood that this disclosure is not limited to the specific compositions, articles, devices, and methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. 
     The following description of the disclosure is provided as an enabling teaching of the disclosure in its currently known embodiments. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the disclosure described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof. 
     Disclosed are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are embodiments of the disclosed method and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein. 
     Reference will now be made in detail to the present preferred embodiment(s), examples of which are illustrated in the accompanying drawings. The use of a particular reference character in the respective views indicates the same or like parts. 
     As noted above, broadly, this disclosure teaches a magnetic polisher and a process to polish an internal surface of a glass sleeve by using a magnetic polisher. The present disclosure involves a process for grinding and polishing the internal surface of a glass sleeve which presents a narrow open frontal area (6-8×60-70 mm) and a deep cavity (120 -140 mm), preventing use of conventional finishing techniques. The glass surface quality, potentially affected by tube reforming processes, may need to be compatible with display applications, optical clarity, non-local deformations or local surface defects, such as pits, scratches, or dimples. These defects may typically have roughness higher than 0.2 nm, for example. The current disclosure may involve a magnetic coupling between one or more inner rotatable polishing tools put in rotation by an external rotating motor. It may also involve a stage or other translation mechanism in order to manage the polishing of a generally rectangular surface with a substantially round tool. The magnetic coupling may be insured by a North or South pole orientation of magnets. 
     The disclosure may present many advantages, such as internal surface finishing of non-accessible flat glass cavity, thin polishing tool being able to enter a fragile narrow glass cavity; magnetic coupling between the polishing tool and an external rotating motor, flexible and compliant polishing tool being able to follow a generally flat surface that could involve a very large radius of curvature (such as several meters). The advantages may further include combined translation motion in order to be able to generate a flat polished surface, use of different grain size grinding and polishing mediums that may be coated papers, fabric or polyurethane pads with free abrasive, possible double side polishing, internal and external at the same time, possible double internal side polishing, cost effective technique that may be applied to finished sleeve enclosure or long sleeve preforms before cutting and edge finishing, control of the grinding and polishing force by variation of the power/density of magnetic elements and/or of the magnetic gap in between the driving and the grinding parts. 
     As used herein, the term “sleeve” describes a three-dimensional, tubular glass article having a non-circular cross section and an aspect ratio greater than 1. The aspect ratio is the ratio of the largest and smallest diameters of the cross section of the tubing or sleeve. The aspect ratio has a minimum value of 1 by definition for a round or axisymmetric tube. The aspect ratio has a value larger than 1 for a flattened sleeve. Optionally in any embodiment, aspect ratios from about 1.5 to about 50, optionally from about 3 to about 39, optionally from about 5 to about 25, optionally from about 5 to about 15, optionally from about 7 to about 11, optionally from about 18 to about 28, are contemplated. 
     While most of the embodiments herein are used particularly in application to sleeve glass enclosures, it is contemplated that the same method could be applied more widely, for example with an additional step of cutting the tubes in half or severing optically flat portions to provide for a 3D shaped cover glass, touch screen, or other part. 
     As shown in the Figures, the magnetic polisher  100  may include at least one rotatable driver  110  and at least one rotatable polishing tool  120 . The at least one rotatable driver  110  may include driver magnetic material, such as a magnet  160 . The at least one rotatable polishing tool  120  may include tool magnetic material, such as a magnet  170 , and a first polishing surface  122 . In one embodiment, the at least one magnet  160  or  170  may include a permanent magnet, such as neodymium magnet, samarium-cobalt or an alloy of neodymium, neodymium-iron-boron (NIB) magnet, for example. The at least one of the driver magnetic material and the tool magnetic material may comprise a magnetic neodymium alloy, such as neodymium-iron-boron magnet. In another embodiment, the magnet  160  for driver magnetic material may be electromagnet. 
     Optionally in any embodiment, the rotatable driver  110  and the polishing tool  120  may be configured to be magnetically coupled with a workpiece  130 , such as a glass sleeve. The rotatable driver  110  may be connected to a driving motor  140 . The rotatable driver  110  may be operated at various speeds ranging from 200 to 800 rpm, for example. The workpiece  130  may have at least a first internal surface  132  to be polished. The workpiece  130  may be located between the first polishing surface  122  and the driver  110  so that rotation of the driver  110  about an axis  102  may cause rotation of the first polishing surface  122  against the first internal surface  132 . The first polishing surface  122  may be defined by a non-magnetic polishing pad  180 . The non-magnetic polishing pad  180  may be used in order to prevent any impact on the magnetic coupling between the polishing pad  180  and the rotatable driver  110 . A magnetic polishing pad  180  may alternatively be used, if desired. 
     The magnetic polisher  100  may further include a variable spacer  140 . The variable spacer  140  may be configured to adjust and maintain the axial distance between the rotatable driver  110  and the rotatable polishing tool  120 , while the first internal surface  132  is located between the first polishing surface  122  and the driver  110  to provide the desired normal force between the first polishing surface  122  and the first internal surface  132 . The variable spacer  140  may allow a fine tuning of the grinding or polishing force. The variable spacer may vary from 2 to 10 mm for 50 N to 5 N corresponding forces, for example. In another embodiment, the variable spacer may be less than 2 mm or more than 10 mm depending on the workpiece  130 . There may be many advantages of using a variable spacer  140 . For example, as one of the advantages, the rotatable driver  110  may be configured to remain out of contact with the workpiece  130 , such as a glass sleeve, when the rotatable driver  110  and the polishing tool  120  are magnetically coupled and the first polishing surface  122  is rotating against the first internal surface  132 . 
     The magnetic polisher  100  may further include a translation stage  150  upon which either the workpiece  130  or the rotatable driver  110  may be mounted. The translation stage may allow the workpiece  130  to be moved relative to the magnetic polisher  100  generally perpendicular to the rotation axis  102 . As shown in  FIG. 2 , for example, the translation stage  150 , such as a translation belt, may be connected to a shaft  210  of the motor so that one motor  140  may control several, such as four, rotatable drivers  110 . The rotatable drivers  110  may in turn control several, such as four, polishing tools  120  to have individual tool  120  overlapping for uniform polishing (as shown in  FIG. 3 ). In this way, the internal surface polishing may be operated on a long sample, such as exceeding one meter, on a multi-head polishing set-up. The translation belt may form a rotating system. 
     As shown in  FIG. 3 , in one embodiment, the workpiece  130 , such as a glass sleeve, to be internally polished may sit on the translation stage  150 , such as a translation belt, being also motorized in order to insure the polishing of the whole internal surface. The translating support may move on both directions covering the whole surface at a rate of 2 to 10 cycles per minute, for example. In another embodiment, the translation stage  150  may be used to translate the rotatable driver  110  relative to the workpiece  130 . 
     The polishing pad  180  may be equipped with one or more magnets. For example, still in  FIG. 3 , the polishing pad  180  may be equipped with four magnets  170 , for example. The four magnets  170  may be arranged spreading out as a cross. In another embodiment, in  FIG. 4 , the polishing pad  180  may have 6 magnets  170 , which equally spread close to the periphery of a polymer disk. As an example, the polymer disk can have a diameter of about 60 mm. The magnet  170  may have 12 mm diameter and 3 mm high iron Neodymium magnet. The magnet  170  may fit into about 6 radial slots  410 . The radial slots may allow some compliancy in addition to polymer intrinsic stiffness that may be adjusted from totally rigid (aluminum), mid stiff (polyvinyl carbonate, Delrin, polypropylene) to soft (polyurethane, silicone), for example. The polishing pad  180  may be 4 mm thick for a 6 mm thick radial slot, leaving enough room for grinding or polishing paper or polyurethane layer usually stuck to it. 
     As shown in  FIG. 5 , the rotatable driver  110  may comprise a driver polishing surface  510  configured to contact an external surface  520  of the workpiece  130  to be polished during rotation of the first polishing surface  122  against the first internal surface  132 . In one embodiment, the driver polishing surface  510  may be defined by a non-magnetic polishing driving pad  500 . The magnetic coupling may be insured by non-magnetic driving pad  500  involving the corresponding set of magnets  160 . These magnets  160  may be advantageously thicker, in order to provide potentially higher coupling forces, or/and larger gap in between pads. In one embodiment, the driving magnets  160  may have about 12 mm diameter, about 6 mm high, for example. Magnets may be secured on polymer pads with bi-component structural adhesives non-sensitive to moisture. Optionally in all embodiments, all magnets on polishing and driving pads may be oriented top north by convention. 
     Still in  FIG. 5 , the polisher  100 , while shown approximately as wide as the glass sleeve, may be substantially smaller than the glass sleeve. The polisher  100  may be moved about the internal or external surfaces of the sleeve in a random or ordered manner in order to deliver uniform surface finishing, for example. 
     The polishing tool may further include a second polishing surface  610  axially separated from the first polishing surface  122 , as shown in  FIG. 6 . The second polishing surface  610  may be configured to contact a second internal surface  620  of the workpiece  130  to be polished during rotation of the first polishing surface  122  against the first internal surface  132 . The second polishing surface  610  may be defined by a second non-magnetic polishing pad  630 . The first and second non-magnetic polishing pad  180  and  620  may be covered by a polishing paper  640 . A polishing tool  100  may further include an expander urging the first and second polishing pads apart, such as an internal spring  600 , a compressive polymer layer or an expandable polymer that functions as a spring, a pneumatic or hydraulic cylinder and piston, an expandable pneumatic or hydraulic diaphragm or bladder, a telescoping lead screw in a threaded sleeve, a magnetic repulsion provided by magnets with facing north or facing south poles, or any other suitable expansion device, to maintain contact between the first and second polishing surfaces  122  and  620  and the first and second internal surfaces  132  and  620 . The expander may help expand the double side polishing pads to polish both internal surfaces of the workpiece. 
     Optionally in any embodiment, a polishing pad, as shown in  FIGS. 5 and 6 , may have rounded edges that contact a part or all of the rounded area of the sleeve. Optionally, the rounded edges may mirror the shape of part or all of the rounded area of the sleeve. For example, the polishing pad may have permanently rounded edges. For another example, the rounded edges of the polishing pad may be composed of a sufficiently flexible material to conform to a part or all of the rounded area of the sleeve during polishing. 
     In another embodiment, a method  700  for polishing a glass sleeve may be carried out as follows, for example. Step  710  is providing a glass sleeve having at least one substantially flat internal surface extending along a longitudinal axis and an internal opening extending along the longitudinal axis, enclosing a space. Step  720  is introducing a rotatable polishing tool comprising a magnetic material, such as a magnetic alloy of neodymium, and a first polishing surface into the space. Step  730  is bringing the first polishing surface into contact with the substantially flat internal surface. Step  740  is introducing a rotatable driver comprising a magnetic material to the exterior of the glass sleeve, wherein at least one of the driver magnetic material and the tool magnetic material is a magnet, such as a neodymium magnet, such that the driver magnetically couples with the polishing tool. Step  750  is rotating the driver, causing the polishing tool to rotate. Optionally in any embodiment, the polishing tool further comprises a second polishing surface axially separated from the first polishing surface. The method further may comprise bringing the second polishing surface into contact with a second substantially flat internal surface of the glass sleeve. Optionally in any embodiment, the driver may further comprise a driver polishing surface. The method  700  may further comprise bringing the driver polishing surface into contact with an external surface of the glass sleeve. 
     The method  700  may be further carried out by biasing the first and second polishing surfaces axially apart against the first and second substantially flat internal surfaces and mounting at least one of the glass sleeve and the rotatable driver upon a translation stage. The translation stage allows at least one of the workpiece and the polishing tool to be moved generally perpendicular to the axis of rotation, relative to the other of the workpiece and the polishing tool. 
     In operation, a glass sleeve may be mounted inside a holder, such as a V-shaped holder, and the following grinding sequence can be used, for example. 
     Grinding paper (600 mesh) may be put on a grinding pad. The glass sleeve may be ground at about 200 rpm, 4×45 mm amplitude during a 2-minute run. The glass sleeve then may be rinsed with water. 
     Grinding paper (1200 mesh) may then be put on the grinding pad. The glass sleeve may be ground at 200 rpm, at 4×45 mm amplitude during a 4-minute run. The glass sleeve then may be rinsed with water. 
     Polishing paper having a 9-micron grid may then be put on a polishing pad. The glass sleeve may be polished at 200 rpm, at 4×45 mm amplitude during an 8-minute run. The glass sleeve may be rinsed with water after that. 
     Polishing paper having a 3-micron grid may be put on the polishing pad. The glass sleeve may be polished at 200 rpm, 4×45 mm amplitude during an 8-minute run. The glass sleeve may be rinsed with water after that. 
     A polyurethane layer may be put on a finishing pad. The glass sleeve may be polished at 200 rpm at 4×45 mm amplitude during an 8-minute run. The glass sleeve may be rinsed with water after that. After the grinding and polishing have been completed, the internal surface may present flattened topography. 
     While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.