Patent Publication Number: US-2021163345-A1

Title: Methods of reinforcing openings in glass and products formed therefrom

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims benefit under 35 U.S.C. § 1.119(b) in U.S., or similar statues in other countries, of U.S. provisional patent application Ser. No. 62/715,496, filed Aug. 7, 2018, entitled METHODS OF REINFORCING OPENINGS IN GLASS AND PRODUCTS FORMED THEREFROM, and also of U.S. provisional patent application Ser. No. 62/795,713, filed Jan. 23, 2019 entitled METHODS OF REINFORCING OPENINGS IN GLASS AND PRODUCTS FORMED THEREFROM, the entire contents of both of which are incorporated herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally directed to a glass product having an opening therethrough which exhibits compressive forces at the opening. 
     BACKGROUND ART 
     Glass may break under certain tensile stress. Where a glass sheet or laminated glass has an opening cut there through, the glass may be weakened. The weakened glass may break more easily and may not hold up to high tensile stress. A sheet of glass having an opening may undergo tempering to provide a strengthened glass sheet. Tempering glass is a thermal or chemical process that provides a strengthened glass sheet having permanent residual internal tension and surface compression. Any openings formed in the glass or shaping of the glass is done prior to thermal tempering as the thermally tempered glass may not be cut after the tempering process. Tempered glass is difficult to break due to the permanent residual surface compression, however, damage to any part the glass may lead to damage of the entire glass sheet. 
     Laminated glass materials may provide more impact protection in a glass material and have various functions. Multiple glass sheets may be combined using various functional intermediate materials. The intermediate materials may function to provide reflective or absorption benefits to the glass laminates or provide switchable functionality. Laminated glass may be desirable over tempered glass where impact is anticipated. The laminate may include at least two glass sheets having an intermediate layer between the glass sheets. The intermediate layer may include, without limitation, a polymer sheet, including polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyethylene terephthalate (PET), or ionomer materials. 
     Providing an opening in a glass sheet or laminated glass sheet may be desirable for various vehicle and architectural applications. However, forming a hole in a glass sheet weakens the glass at the opening. It is not always desirable or possible to temper glass for various applications. Therefore, it is desirable to provide a laminated glass material which may support an opening therethrough. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates generally to a glass product comprising: a glazing having at least one glass sheet; an opening extending through at least part of the glazing; a first bushing extending through the opening; and an adhesive provided between an edge of the opening and an outer edge of the first bushing, wherein compressive stress is formed in the glazing around the opening in the glazing by contraction of the first bushing. 
     In some embodiments, the glazing comprises a first glass sheet, a second glass sheet facing the first glass sheet, and an intermediate layer formed between the first glass sheet and the second glass sheet. The thickness of at least one of the first glass sheet and the second glass sheet is preferably chosen from 0.1 to 12 mm, and the thickness of at least one of the first glass sheet and the second glass sheet is more preferably chosen from 0.3 to 5.0 mm and even more preferably from 0.4 to 2.3 mm. 
     In further embodiments, the bushing is subject to tension. The bushing may have a diameter less than an original diameter of the opening. The adhesive may be thermally, chemically, or ultraviolet radiation cured. The bushing may be made of a metal or metal alloy, and preferably may be aluminum or its alloy. 
     In further embodiments, the bushing comprises a flange and a body, wherein the flange extends outside of the opening against an outer surface of the glazing and the body of the bushing extends through the opening. 
     Further embodiments include an edge of the opening which has a roughness (Ra) of less than 2.5 μcm. In further embodiments, a seal may be provided at the opening, and may be attached to the bushing. In certain embodiments, the glass product may include a second bushing. 
     In another aspect of the present disclosure, a glass product includes a glazing having at least one glass sheet, an opening extending through the glazing; and a stress generating member which extends through the opening to contacting an edge of the opening wherein the stress generating member generates compressive stress in the glazing around the opening. In further embodiments, the stress generating member is made of a resin, wherein the resin decreases in size when the resin is cured. The glazing may include a first glass sheet, a second glass sheet facing the first glass sheet, and an intermediate layer formed between the first glass sheet and the second glass sheet. In some embodiments, the resin may be cured thermally, chemically, or by ultraviolet radiation. The opening edge may have a surface roughness of less than 2.5 μm. Further embodiments may include a seal provided through the opening. 
     The present disclosure relates generally to a method of forming compressive stress at an opening in a glazing, comprising: placing at least one bushing extending through the opening, wherein an adhesive is on an outer edge of the bushing, expanding the outer edge of the bushing at a higher rate than any expansion of the glazing to provide the bushing in an expanded state, curing the adhesive between the bushing and the opening to bond the bushing to an edge of the opening, and allowing the bushing to decrease in size from the expanded state, wherein the adhesive remains adhered to the outer edge of the bushing and the edge of the opening, wherein compressive stress is formed in the glazing around the opening. 
     In certain embodiments, the glazing does not expand. The adhesive may, in some embodiments, be cured by ultraviolet radiation, thermal, or chemical curing. In some embodiments, expanding the outer edge of the bushing comprises heating the bushing and allowing the bushing to decrease in size from the expanded state comprises allowing the bushing to cool. The adhesive may be thermally cured. 
     In further embodiments, the bushing is expanded by applying a mechanical force to the bushing and decreases in size from the expanded state when the mechanical force is removed from the bushing. In additional embodiments, the adhesive is cured using ultraviolet radiation, thermal, or chemical curing before the mechanical force is removed from the bushing. 
     In further embodiments, the adhesive has an outer diameter equal to a diameter of the opening when the bushing is in the expanded state. 
     In further embodiments, a method of forming a compressive stress at an opening in a glazing, in accordance with further embodiments, includes the steps of placing a stress generating member on an edge of the opening in the glazing, and curing the stress generating member on the edge of the opening, wherein the stress generating member decreases in size and remains adhered to the edge of the opening in the glass substrate to form compressive stress in the glazing around the opening. In certain embodiments, the stress generating member may be cured thermally, chemically, or by ultraviolet radiation. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more example aspects of the present disclosure and, together with the detailed description, serve to explain their principles and implementations. 
         FIG. 1  shows a glass product with an opening. 
         FIG. 2  shows an exemplary glass product with an opening having an adhesive and a bushing therein. 
         FIG. 3  shows an opening having an adhesive and a bushing where the opening is under compressive stress, according to an exemplary embodiment of the present disclosure. 
         FIG. 4  shows an end view of a bushing with a flange, according to an exemplary embodiment of the present disclosure. 
         FIG. 5  shows a side view of the bushing with the flange shown in  FIG. 4 . 
         FIG. 6  shows a cross section at an opening of a glass product in an expanded state. 
         FIG. 7  shows a cross section at an opening of a glass product in a contracted state, according to an exemplary embodiment of the present disclosure. 
         FIG. 8  shows a cross section at an opening of a glass product according to another exemplary embodiment of the present disclosure. 
         FIG. 9  shows a glass product according to yet another exemplary embodiment of the present disclosure. 
         FIG. 10  shows a glass product according to a further exemplary embodiment of the present disclosure. 
         FIG. 11  shows a glass sheet having an aluminum bushing and an adhesive within an opening in the glass. 
         FIG. 12  shows a piece of glass having an opening under compressive stress in front of a polarization wall. 
         FIG. 13  shows a piece of glass having an opening under compressive stress in front of a polarization wall. 
         FIG. 14 a    shows measurements of the glass opening in flat glass with a stress meter having a bushing for reinforcement of the glass opening. 
         FIG. 14 b    shows measurements of the glass opening in flat glass with a stress meter having a bushing for reinforcement of the glass opening. 
         FIG. 15 a    shows measurements of a glass opening in bent glass with a stress meter prior to reinforcement of the glass opening. 
         FIG. 15 b    shows measurements of a glass opening in bent glass with a stress meter prior to reinforcement of the glass opening. 
         FIG. 16 a    shows measurements of a glass opening in bent glass with a stress meter having a bushing for reinforcement of the glass opening. 
         FIG. 16 b    shows measurements of a glass opening in bent glass with a stress meter having a bushing for reinforcement of the glass opening. 
         FIG. 17  is a cross section showing a glass opening in a glass product with a wiper device according to yet another exemplary embodiment of the present disclosure. 
         FIG. 18  is a cross section showing a glass opening in a glass product according to a further exemplary embodiment of the present disclosure. 
         FIG. 19  is a cross section showing a glass opening in a glass product according to a yet another exemplary embodiment of the present disclosure. 
         FIG. 20  is a cross section showing a glass opening in a glass product according to a further exemplary embodiment of the present disclosure. 
         FIG. 21  illustrates a manufacturing process for a glass product with a reinforced opening according to an exemplary embodiment of the present disclosure. 
         FIG. 22  illustrates a manufacturing process for a glass product with a reinforced opening according to another exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is a glass product having compressive stress which strengthens an opening through at least part of the glass product and a method of making such a glass product. In the following description, for purposes of explanation, specific details are set forth in order to promote a thorough understanding of one or more aspects of the disclosure. It may be evident in some or all instances, however, that any aspect described below can be practiced without adopting the specific design details described below. 
     Creating an opening within a glass sheet may weaken the glass around the opening, which may lead to cracks in the glass. Mechanical stress may further create a risk of fractures in the glass where a mechanical feature is moved through or within the glass opening. Openings in glass may be desirable for various applications, including, but not limited to, a hole for the placement of a wiper in an automotive window, openings for attaching a side window within a vehicle door, openings for an antenna or camera, openings for the attachment of luggage rails on a sunroof, an opening for placing a handle in a glass door, and connecting electrical devices, including those within a glass laminate. Therefore, there is a need to strengthen glass products having an opening therethrough. 
     Compressive stress may be introduced to a glass sheet to improve the glass strength. Described herein are glass products having a strengthened opening therethrough and methods for introducing compressive stress to an opening in the glass products. As used herein, “glass product” may include a glazing and any other assembled parts. A glazing may include a single glass sheet or multiple glass sheets which are laminated together. The glazing may include, for example, a first glass sheet, a second glass sheet facing the first glass sheet, and an intermediate layer formed between the first glass sheet and the second glass sheet. Materials of the glass product may be any inorganic and organic glasses, including but not limited to, soda-lime silica glass, alumino silicate glass, boro-silicate glass, silica glass, and acrylic glass. The glass used in such products may be any thickness. Preferably, openings in glass sheets from 0.1 to 12 mm thick may be strengthened with the disclosed methods. More preferably, the glass sheets are from 0.3 to 5.0 mm and even more preferably from 0.4 to 2.3 mm thick. In a laminated glass product having more than one glass sheet, the glass sheets may have the same or different thicknesses. Glass sheets having a reinforced opening as disclosed herein may be flat or bent. Further, the glass sheets having the reinforced opening may include tempered glass or non-tempered glass, where additional reinforcement may be desired. In some embodiments, the reinforced opening may be formed prior to tempering the glass. 
     A glass product  10  for use in a vehicle is illustrated in  FIG. 1 . The glass product  10  includes an opening  14  that extends through a glazing  12 . The opening  14  near the bottom of the glazing  12  may be used for a wiper mechanism which may extend through the opening  14 . An opening  14  may be formed in any suitable position(s) in the glazing  12 , including for additional uses, such as luggage racks and handles. Further some glazings  12  may include more than one opening  14 . The opening  14  may be formed by various methods known, including, but not limited to, mechanical drilling, water jet drilling, chemical etching, and laser drilling. Openings in the glazing  12  may be various sizes and shapes, including, but not limited to, circular or oval. 
     The edge of the opening  14  may be formed to provide a minimum roughness at the opening edge. Less surface roughness at the opening  14  may improve resistance to form cracks in the glass. A rough edge may include stress concentrations which may lead to breaks in the glass. A smoother (less rough) edge reduces the stress concentrations and may improve resistance to cracks. The opening edge may have a roughness (Ra) preferably less than 2.5 μm, more preferably less than 2 μm, or even more preferably less than 1.5 μm. The surface roughness may be measured according to ISO standard 13565-1 (1996) at a cut-off wavelength λc is 2.5 μm and λs is 2.5 μm. Chemical etching or laser drilling methods of forming the opening may be preferable to minimize the opening edge roughness. Mechanical drilling may also create a smooth opening, with or without additional finishing, such as polishing. The edge of the opening  14  includes the inner surface of the opening between a first face  12   f  of the glazing  12  and a second face  12   b  of the glazing  12  where the opening  14  is formed through the glass product  10 . 
       FIG. 2  illustrates the glazing  12  having the opening  14  with a bushing  16  and an adhesive  18  within the opening  14 . A bushing  16  used may be any material that may expand and then decrease in size, or namely, may be provided to expand and contract. The bushing  16  has an original diameter that is less than the original diameter of the opening  14 , wherein the “original diameter of the bushing” is the outer diameter of the bushing prior to expansion. The “original diameter of the adhesive” is the outer diameter of the adhesive  18  prior to expansion and curing. The “original diameter of the opening” is the diameter of the opening  14  when it is cut into the glass, prior to reinforcement. In some embodiments, the adhesive  18  may have a thickness less than one half of the difference in diameter between the bushing  16  and the opening  14 . 
     In certain embodiments, the bushing  16  may include a flange  22  which extends out of the opening  14  and along the glazing  12  when the bushing  16  is in place in the opening  14 .  FIG. 4  shows the bushing  16  with a flange  22  when viewed from a bottom end of the bushing  16  and  FIG. 5  shows the bushing  16  with a flange  22  when viewed from a side. The bushing  16  may include a flange  22  which extends along at the outer surface of the first glass sheet or the outer surface of the second glass sheet when the bushing  16  is placed within the opening  14 . An outer circumference of the flange  22  may be greater than the outer circumference of a bushing body portion  24  which extends through the opening  14  formed in the glazing  12  and greater than the circumference of the opening  14 . The flange  22  may aid in the alignment of the bushing  16  within the opening  14  prior to curing the adhesive  18 . The thickness of the bushing  16  may depend on the bushing material. A weaker material may require a thicker bushing  16 , while a stronger material may allow for a thinner bushing  16 . A sufficient strength is required to maintain the compressive force in the glazing  12  at the opening  14 . The bushing  16  may be various materials, including, but not limited to, metal or plastic. Metals which may be used include, but are not limited to, aluminum, copper, steel, tin, zinc, lead, titanium, and iron. In further embodiments, the bushing  16  may be made of an alloy of any suitable metal(s), including aluminum, copper, steel, tin, etc. The bushing  16  material may be selected for a particular Young&#39;s modulus and/or thermal expansion coefficient based on the glass sheet material(s) and the adhesive  18  used. In certain embodiments, the bushing  16  may be formed in a ring or cylindrical shape. Preferably, the bushing  16  may have a shape which is complementary to the shape of the opening  14 . Further, a bushing  16  may include a narrow slit or slits substantially extending in a thickness direction or oblique directions of the glazing, which may aid expansion and contraction. Furthermore, in some embodiments, a bushing may be made of multiple body parts connected to each other. In certain embodiments, there may be more than one bushing  16  within the opening  14 . For example, bushings  16  may be placed through the opening  14  from opposite sides of the glazing  12 . 
     The methods described herein for introducing a compressive stress to the opening  14  in the glazing  12  may be used in any glass products, including, but not limited to, glazings which are individual glass sheets or glass laminates. Where more than one glass sheet is used in a glass laminate, the opening may be cut in the glass sheet(s) before or after lamination. Further, the opening  14  may be formed through flat glass or bent glass. In some embodiments including a laminated glazing  12 , where the opening  14  is formed prior to lamination, the opening  14  may be cut into stacked glass sheets or the glass sheet openings may be cut into each glass sheet separately. Where the opening  14  is cut into glass sheets separately, prior to lamination, the opening cuts may not align completely. A bushing  16  may be used on each side of a laminated glass product to provide compressive strength to each glass sheet in the laminate separately, i.e. more than one bushing  16  may be used in an opening  14 . In further embodiments, the opening  14  may be formed in an already laminated glazing  12 . In a laminated glazing  12 , the opening  14  may be used with one or multiple bushings  16 . 
       FIG. 3  shows an opening  14  having a compressive stress formed by an adhesive  18  provided between the opening  14  and a bushing  16 . In some embodiments, the bushing  16  may expand with the adhesive  18  placed between the bushing  16  and the opening  14  to adhere the bushing  16  to the opening  14 . The method used to expand the bushing may include, but is not limited to, thermal and/or mechanical forces. In the case of a thermally expanded bushing  16 , the bushing  16  may have a thermal expansion coefficient larger than the glazing  12 . Thus, upon heating, the bushing  16  may expand at a higher rate than the glazing  12 , and the outer edge of the bushing  16  within the opening  14  may be adhered to the edge of the opening  14  in an expanded state. Thermal treatment may be applied to the entire glazing  12  or local to the bushing  16 . The bushing  16  may be substantially the same shape as the opening such that the bushing  16  may be adhered to the entire edge of the opening  14  in an expanded state. It may be preferable in some embodiments to form a uniform adhesion around the edge of the opening  14  such that in a contracted state, there may be even compression in the glazing around the opening. Preferably, the adhesive  18  provided between the bushing  16  and the opening  14  is thermally cured while the bushing  16  is in an expanded state. The bushing  16  may then be cooled, and the bushing  16  may decrease in size to a contracted state. The bushing  16  may remain attached to the opening edge, forming a compressive stress in the glazing around the opening  14 . The glazing  12  is thus strengthened at the opening  14 . The adhesive  18  may be compressed between the edge of the opening  14  and the bushing  16  when the bushing  16  is in an expanded state. In some embodiments, as shown in  FIG. 3 , the adhesive  18  may remain compressed after the bushing  16  is in a contracted state. The temperature difference between a heated state and a cooled state is not limited and may be more than or equal to 50 K, 80 K, or 100 K. The difference in temperature may depend on the thermal expansion coefficient and Young&#39;s modulus of the bushing and the glass and desired compressive stress to be formed. 
       FIG. 6  and  FIG. 7  cross-sectionally illustrate the opening  14  formed in the glazing  12  and its vicinities, where  FIG. 6  shows the bushing  16  in an expanded state, and  FIG. 7  shows the bushing  16  in a contracted state. In  FIGS. 6 and 7 , the glazing  12  is formed of a first glass sheet  26 , a second glass sheet  28  facing the first glass sheet  26 , and an intermediate layer  30  formed between the first glass sheet  26  and the second glass sheet  28 . The intermediate layer  30  may be made of any suitable material, including a polymer sheet, such as polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), or polyethylene terephthalate (PET), or ionomer materials. As shown in  FIGS. 6 and 7 , the bushing  16  shown has a flange  22  extending over the first surface of the first glass sheet  26  from the edge of the opening  14 . In some embodiments, the flange may be placed to extend over the outer surface of the second glass sheet. In the expanded state, as shown in  FIG. 6 , the bushing  16  has an outer diameter D B1  whereas the opening  14  has an inner diameter D E1 . To reach an expanded state, in some embodiments, the bushing  16  may be heated or mechanically expanded to increase the outer diameter D B1  to be larger in size, so that the outer diameter D B1  becomes larger than the original outer diameter of the bushing  16 . Where the bushing  16  is in an expanded state, the inner diameter D E1  of the opening  14  may, in some embodiments, be larger than the original inner diameter of the opening  14 . The inner diameter D E1  of the opening  14  may be the same or larger than the original inner diameter of the opening  14  when the bushing  16  is in an expanded state. Where the inner diameter D E1  of the is larger than the original inner diameter of the opening  14 , the bushing  16  has a larger expansion ratio than the glazing  12  forming the opening  14 . In the expanded state, the adhesive  18  receives compressive force from the outer peripheral wall, or the outer circumference, of the bushing body portion  24 . 
     Prior to removal of the application of heat or mechanical force, the adhesive  18  placed between the bushing  16  and the edge of the opening  14  may be cured adequately by heating, ultraviolet (UV) radiation, or any other suitable means. After the adhesive  18  is cured, the heat or mechanical force used to expand the bushing  16  may be removed. Upon removal of the heat or mechanical force, the bushing  16  may gradually reduce in size to have a smaller outer diameter D B2 , and the opening  14  in the glazing  12  may reduce in size to have an inner diameter D E2 . The outer diameter D B2  of the bushing  16  in the contracted state is smaller than the outer diameter D B1  of the bushing  16  in the expanded state. The inner diameter D E2  of the opening  14  in the contracted state is smaller than the inner diameter D E1  of the opening  14  in the expanded state. Because the bushing  16  shrinks after the adhesive  18  is cured, the adhesive  18  is pulled inwardly in the radial direction of the opening  14 , so that the edge of the opening  14  receives force pulled inward, thereby forming compressive stress in the glass around the opening  14 . The adhesive  18  may also decrease in size (based on an inner diameter of the adhesive  18 ) upon curing and removal of the heat or mechanical force. Preferably the adhesive  18  has a thermal expansion coefficient greater than or equal to the thermal expansion coefficient of the bushing  16 . The adhesive  18  may include, but is not limited to, an epoxy or polyurethane. The adhesive  18  used may have an Young&#39;s modulus similar to that of the bushing  16 . The adhesive  18  may have sufficient strength to maintain the compressive stress in the glass by keeping the opening edge adhered to the bushing  16  after the bushing  16  decreases in size. 
     In some embodiments, where the bushing  16  is thermally expanded and the adhesive is thermally cured, the bushing  16  expansion and adhesive  18  curing may be done in an autoclave. The autoclave may be used in preparation of a glass laminate, which can be done at the same time as the thermal bushing  16  expansion and adhesive  18  curing where the glazing  12  is a laminated glazing. In further embodiments, thermal expansion and/or curing may also be induced by applying heat directed at the bushing  16  and/or adhesive  18 . 
       FIG. 8  to  FIG. 10  illustrate further embodiments of the glass products according to aspects of the present disclosure.  FIG. 8  shows a glass product  33  having a single glass sheet  32  as a glazing. The glass sheet  32  may have a cylindrical shaped opening  31  into which a cylindrical bushing  36  may be inserted. An adhesive  34  may be placed between the outer periphery of the bushing  36  and the inner periphery of the opening  31 . The adhesive  34  may be placed on the outer perimeter of the bushing  36  prior to placing the bushing  36  in the opening  31 . In some embodiments, the adhesive  34  may be placed around the edge of the opening  31  prior to placement of the bushing  36  within the opening  31 . The bushing  36  may be expanded and then contracted to produce compressive stress in the glass around the opening edge of the single glass sheet  32 . Because the compressive stress is formed in the glass around the opening edge of the single glass sheet  32 , the glass product  33  may have a durable structure, particularly around the edge of the opening  31 . 
       FIG. 9  shows another embodiment including a glass product  37  with a glazing made of a first glass sheet  38 , a second glass sheet  42  facing the first glass sheet  38 , and an intermediate layer  40  formed between the first glass sheet  38  and the second glass sheet  42 . An opening  44  may be formed through the second glass sheet  42 , such that the opening  44  does not extend through the first glass sheet  38 . In certain embodiments, the intermediate layer  40  may also remain without an opening or hole. It may be preferable that the opening  44  be formed in the second glass sheet  42  prior to lamination of the first glass sheet  38  and the second glass sheet  42 . A bushing  46  may be arranged within the opening  44 , and an adhesive  48  may be provided between the outer periphery of the bushing  46  and the inner periphery of the opening  44 . The bushing  46  may be expanded and then contracted to produce compressive stress in the glass around the opening edge of the second glass sheet  42 . Because the bushing  46  diameter is reduced, the circumference of the opening in the second glass sheet  42  attached to the bushing  46  by adhesive  48  is reduced, compressing the glass at the edge of the opening. Accordingly, the second glass sheet  42  is structured with added strength around the opening  44  due to the compression. 
       FIG. 10  further shows an embodiment of a glass product  51  having substantially the same glass structure as that of the glass product  37  shown in  FIG. 9 . The glass product  51  may include a glazing including a first glass sheet  50 , a second glass sheet  54  facing the first glass sheet  50 , and an intermediate layer  52  formed between the first glass sheet  50  and the second glass sheet  54 . An opening  55  may be formed through the second glass sheet  54 , such that the opening  55  does not extend through the first glass sheet  50 . The intermediate layer  52  may include an opening aligned with the opening  55  in the second glass sheet  54 , or in certain embodiments, the intermediate layer  52  may remain without an opening. A bushing  56  may be arranged within the opening  55  and an adhesive  57  may be provided between the outer periphery of the bushing  56  and the inner periphery of the opening  55 . As shown in  FIG. 10 , an electronic connector  58  may be provided within the glass product  51 . An electronic connector  58  may be used to provide power to various features, such as, e.g., an organic light emitting device, including an electronic display, a coating, or a heatable wire, including for defrosting a wiper park area. The electronic connection  58  may include a connector, such as a wire or cable  60  which may be connected to a power source and may extend out of the opening  55  through an inner circumference of the bushing  62 . The electronic device  58  and the cable  60  may exert force to the glass around the bushing  56  due to the thicknesses of the connector, however, the second glass sheet  54  is strengthened by the formation of compressive stress at the opening  55  in the second glass sheet  54 , such that the glass product  51  significantly reduces any occurrence of cracking. The electronic connector  58  may be placed between the second glass sheet  54  and the intermediate layer  52  or between the first glass sheet  50  and the intermediate layer  52 . Further, the electronic device  58  can be arranged between intermediate layers where two or more intermediate layers are in the laminated glass product. In some embodiments, the electronic connector  58  may be provided within the opening  55 . The opening  55  may be any suitable size to provide electrical connection to a power source. 
     In some embodiments, a mechanical force may be used to expand the bushing  16  within the opening. The mechanical force may be used to expand the bushing  16  towards the edge of the opening  14 . The bushing  16  may be flat or have a three dimensional shape along an inner circumference. In certain embodiments, the bushing  16  may include a threaded shape in an inner circumference of the bushing  16  such that mechanical expansion of the bushing  16  may use the threaded shape. The adhesive  18  may be provided as a layer disposed on the outer circumference of the bushing  16  and may expand with the bushing  16  under the mechanical force to an expanded state. In the expanded state, the diameter of the adhesive  18  may be substantially equal to the diameter of the opening. The adhesive  18  may be cured while the bushing  16  is in an expanded state, adhering the bushing  16  to the opening  14 . The adhesive  18  in such cases may be by any suitable means, including thermal, chemical, or UV radiation treatment. When the mechanical force is removed, the bushing  16  and the adhesive  18  may decrease in size. The bushing  16  may remain adhered to the edge of the opening  14  which may form compressive stress in the glass at the opening  14 . The glass may thus be strengthened at the opening  14 . Mechanical expansion of the bushing  16  may be performed within openings in individual glass sheets or laminated glass products. 
     For example,  FIG. 11  shows an exemplary embodiment of the present disclosure. Particularly, the example includes a 3.15 mm thickness soda-lime silica glass sheet  70  having an opening  72  that is 26.8 mm. As disclosed herein, a glass sheet for use as an individual glass sheet or as part of a lamination, may have any suitable thickness. An aluminum bushing  74  having a 25 mm original outer diameter was placed within the glass sheet opening  72 . The inner aluminum bushing diameter, as shown in  FIG. 11 , is 22 mm. The preferable inner diameter of the bushing  74  may depend on the intended use of the opening. The size of the opening  72  and the bushing  74  used therein are not limited and may be any suitable size, which may be large or smaller than the embodiment shown in  FIG. 11 . A two-component epoxy resin adhesive was placed between the aluminum bushing  74  and the glass opening  72 . The glass  70  having the bushing  74  and the adhesive extending around the opening  72  was heated to 140° C. The bushing  74  and adhesive expanded to the diameter of the opening  72  and the adhesive was cured at this temperature. Upon cooling, the bushing  74  reduced in size but remained adhered to the opening  72 .  FIGS. 12 and 13  illustrate stress at a reinforced opening in glass against a polarization wall after cooling.  FIG. 13  shows the glass sheet of  FIG. 12  which was rotated 90°, which shows that the compression is present around the entire opening. As shown in  FIGS. 12 and 13 , the white ring-like portion  76  shows an adhesive formed between the glass opening edge and the bushing  74 . A layer of compressive stress was visible in each of  FIGS. 12 and 13  around the entire bushing. 
       FIGS. 14 a , 14 b    show measurements using a stress meter, EdgeMaster 2 (Stress Photonics, Inc.), to verify the polarization wall findings in a flat glass sheet sample as shown in  FIG. 11 . The compressive stress was formed along the edge of the opening Op 1  as measured by the EdgeMaster 2. Compressive stress was found between the bushing Bu 1  and the outer perimeter Eg 1  of the glazing. More specifically, as shown in  FIG. 14 a   , a region between the glass outer perimeter Eg 1  and the bushing Bu 1  was subject to compressive stress, which is indicated as a relatively white area Ac 1  in  FIG. 14 a   . This relatively white area Ac 1  was shown in  FIG. 14 b    as the area having stress measured below zero just outside of the bushing Bu 1 . Because the relatively white area Ac 1  is formed at the outer circumference of the opening Op 1 , the glass product is made with higher resistance against cracking around the opening Op 1 . 
       FIGS. 15 a , 15 b    and  FIGS. 16 a , 16 b    show another glass product sample which includes a bent glass sheet.  FIGS. 15 a , 15 b    includes stress measurements of a bent glass sheet having an opening Op 2  without reinforcement and  FIGS. 16 a , 16 b    include stress measurements of the bent glass sheet having an opening Op 3  after reinforcement with a bushing Bu 3  as disclosed herein. 
       FIGS. 15 a , 15 b    show stress measurements of a bent glass sheet having an opening Op 2  cut through the glass sheet without any reinforcement at the opening Op 2 . Where no reinforcement is made to the glass sheet at an opening, the glass sheet between the opening Op 2  edge and the glass outer perimeter Eg 2  was subject to tension, as shown in  FIG. 15 b   , where the area Ar 2  between the opening Op 2  and the glass outer perimeter Eg 2  had a measured stress greater than zero. The area Ac 2  near the glass outer perimeter Eg 2  had slight compression as shown. 
     After the reinforcement is given to the glass substrate, the stress level was largely changed.  FIGS. 16 a , 16 b    show the compressive stress formed with a bushing reinforcement at an opening Op 3  in the bent glass. The EdgeMaster 2 stress meter was used to measure the stress at the opening Op 3  in the glass sheet. With reinforcement, the glass substrate around the opening Op 3  was under compression with a stress measurement of area Ac 3  in the glass, between the opening Op 3  and the outer perimeter Eg 3 , below zero. The relatively white area Ac 3  close to the bushing Bu 3  was turned into the area subject to compressive stress from the area subject to tension, and further, a relatively black area Ar 3  between the relatively white areas Ac 3  and Ac 4 , strongly subject to tension without the reinforcement, was in slight tension, closer to compression after reinforcement. From the comparison with the measured levels, the compressive stress was formed in the glass substrate around the bushing Bu 3  upon application of the reinforcement. Accordingly, the glass product with reinforcement was made with higher resistance against cracking at an opening than the glass product without reinforcement. 
     The glass products described above may be manufactured by any suitable means. For example, glass products may be produced by the steps as follows. First, a glazing may be prepared for fabrication of the glass product. The glass product can be made of a glazing in form of a single glass sheet, a laminated glazing, or any other suitable glazing. An opening may be formed by any suitable means, such as drilling or chemical etching the glazing, such that a hole is formed through all or part of the glazing. The opening may be any suitable shape, such as a circle or an oval. A rectangular shaped or any other polygon shaped opening may be used. In some embodiments including a laminated glazing, openings may be formed in one or more glass sheets prior to lamination. In such laminated glazings, the opening may extend through the entire glazing or part of the glazing, where at least one glass sheet does not include an opening. 
     Where the opening is circular, after formation of the opening in the glazing, a circular bushing having a diameter slightly smaller than the diameter of the opening, is provided within the opening, wherein an adhesive may be provided on the outer circumference of the bushing. In some embodiments, the adhesive may be applied to the edge of the opening or a gap between the outer periphery of the bushing and the inner wall of the opening may be filled with an adhesive. The bushing may be expanded by application of heat or mechanical force. A heat application may be made by applying heat to the inside of the bushing by a heat source such as, e.g., an electrical heater. To uniformly expand the bushing in the circumferential direction, the heat source may be in a cylindrical shape as to uniformly heat the inner peripheral surface of the bushing. In some embodiments, a heat source may surround the entire glass product or apply heat locally to the bushing from a side or sides. Where a mechanical force is used for expanding the diameter of the bushing, a cylindrical device gradually enhancing its diameter may be used. In certain embodiments, a device capable of applying heat and mechanical force at the same time may be useful to expand the bushing. Subsequently, the adhesive may be cured by any suitable means, including heat application where the adhesive is thermosetting. Some adhesives may be cured by mixing components, including a hardening agent. If a UV radiation curable resin is used, the UV radiation curable resin may be cured by ultraviolet radiation. 
     After the bushing is expanded and the adhesive is cured, the bushing may be reduced in size. Where expansion was achieved by heating, the bushing may contract when the bushing returns to room temperature. Alternatively, where the bushing is expanded by mechanical force, such application of force is removed to reduce the size of the bushing. 
     Compressive stress may be formed around the opening in the glazing, where the bushing reduces the size thereof, such that the strength of the glass around the opening is strengthened, thereby reducing the risk of cracking. 
     In certain embodiments, a seal may be provided at the opening, for example, to interact with a device extending through the opening. In  FIG. 17 , a seal  82  is shown around an opening  80 . The opening  80  is formed in a glazing  84 , which is made of a first glass sheet  86 , a second glass sheet  88  facing the first glass sheet  86 , and an intermediate layer  90  formed between the first glass sheet  86  and the second glass sheet  88 . A bushing  98  may be provided in the opening  80  via an adhesive  99 . In some embodiments, the glazing may be a single glass sheet. A wiper mechanism  92  serving as a device for wiping the surface of the glazing  84  is provided so as to extend through the seal  82  by a shaft  96  of the wiper mechanism  92 . The seal  82  made of a rubber material in certain embodiments. The seal  82  may further protect the glazing around the opening by preventing damage due to impact or unwanted force. 
     The seal may be any material, including synthetic or natural rubber or other polymer materials. Where the seal is a rubber it may include vulcanized rubber. The seal may be formed with the bushing, attached to the bushing or otherwise used in an assembly described herein including a bushing. The seal may further be used in an assembly described herein with no bushing. 
     In a further embodiment, compression may be formed at a glass opening without a bushing. A shrinking material which decreases in size after curing may be placed along the edge of the opening and cured in place along the opening edge. Preferably, the shrinking material may decrease in size as the shrinking material is cured. The shrinking material may include, without limitation, a polyurethane. The shrinking material may remain attached to the glass opening edge after curing and decreasing in size and a compressive stress is formed at the glass opening. The shrinking material is in tension in the cured, decreased size state. A seal may further be used in the opening to form a seal with a mechanism extending through the opening. Preferably the shrinking material adheres to the edge of the glass opening.  FIG. 18  illustrates such a shrinking material reinforcing an opening in a glazing. 
       FIG. 18  shows a glazing  100  with an opening  102  extending through the glazing  100 . A shrinking material made stress generating member  104  is provided extending through the opening  102  and contacting the edge of the opening  102  to generate a compressive stress at an edge of the opening  102  in the glazing  100 . The stress generating member  104  may be made of a resin compound decreasing in size after adhering to the edge of the opening  102  in the glazing  100 . With the contraction of the stress generating member  104 , the compressive stress may be formed at the edge of the opening  102  to strengthen the glazing  100  at the opening  102 . In some embodiments, the glazing  100  may be a single glass sheet or a laminated glazing, as shown in  FIG. 19 . A single glass sheet may further be used in a laminated glazing, in some further embodiments. 
     In  FIG. 19 , a glazing is provided having a first glass sheet  106 , a second glass sheet  110  facing the first glass sheet  106 , and an intermediate layer  108  formed between the first glass sheet  106  and the second glass sheet  110 . An opening  114  is formed as to extend through the glazing, and a stress generating member  112  is provided on an inner wall of the opening  114 . The stress generating member  112  is made of a resin compound decreasing in size after adhering to the inner wall of the opening  114  in the glazing. With the contraction of the stress generating member  112 , compressive stress is generated in the glazing around the opening  114 , which provides strength to the glazing around the opening  114  to strengthen the glazing. Alternatively, in some embodiments, the opening may be formed as to penetrate only the second glass sheet such that the glazing may be suitable for connecting an electronic device such as, e.g., an organic light emitting device or a heatable print or coating, as described above. 
       FIG. 20  shows a glass product according to an exemplary embodiment of the present disclosure. Particularly,  FIG. 20  shows a glazing having an opening  114  extending therethrough. The glazing may include a single glass sheet or a laminated glazing. In some embodiments, the single glass sheet may further be used in a laminated glazing. As shown in  FIG. 20 , a stress generating member  113  may extend along the edge of the opening  114  and along one or more of the outer glazing surfaces. 
     According to aspects of the present disclosure, referring to  FIG. 21 , a manufacturing process of a glass product having a reinforced opening may comprise the following steps. 
     Step  2102  includes forming at least one opening in a glazing. The glazing may include a single glass sheet or laminated glass sheets. Where the glazing is laminated glass sheets, the opening may be formed before or after lamination. Step  2104  includes placing at least one bushing extending through the opening, wherein an adhesive is on an outer edge of the bushing. Step  2106  includes expanding the bushing with an external force. The external force may include any suitable means, including heating or mechanical expansion. Step  2108  includes curing the adhesive between the bushing and the opening in the glazing. Step  2110  includes removing the external force from the bushing, such that the bushing decreases in size, creating compression in the glazing around the opening. 
     According to aspects of the present disclosure, referring to  FIG. 22 , a manufacturing process of a glass product having a reinforced opening may comprise the following steps. 
     Step  2202  includes forming at least one opening in a glazing. Step  2204  includes placing at least one stress generating member within the opening. Step  2206  includes curing the stress generating member such that the stress generating member decreases in size, forming compressive stress in the glazing around the opening. 
     The above description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the common principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Further, the above description in connection with the drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. 
     Furthermore, although elements of the described aspects and/or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or embodiment may be utilized with all or a portion of any other aspect and/or embodiment, unless stated otherwise. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.