Method of forming an edge finished hole in a glass sheet

Abstract

Methods of forming a hole in a sheet of glass include forming a hole extending through the glass sheet from a front surface to a back surface and treating an edge of the hole with heat to remove defects caused during the formation of the hole. The methods include a heat chamfering process that heats the hole with a heating filament while cooling the sheet of glass. The methods also includes directing a plasma plume generated by a plasma torch onto the hole to reflow and reheal a portion of the glass at the hole.

Description

Atorney Docket No.: SP25-024 METHOD OF FORMING AN EDGE FINISHED HOLE IN A GLASS SHEETCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 763,850 filed February 26, 2025, the content of which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure generally relates to glass processing of cut out through holes, and more particularly relates to the formation of a smooth finished hole in a sheet of glass, including related methods.BACKGROUND

[0003] Glass sheets are often employed in glass-to-glass solar panels and may include one or more feed-through holes typically formed by laser cutting or mechanical drilling in the glass sheet on the back side of the solar panel for routing electrical leads to connect internal solar cells to external junction boxes. The junction box feed-through holes formed in the glass sheet often exhibit damaged and / or weakened edges caused by the abrasive cutting with the laser or drill which may result in the glass sheet being susceptible to further damage during extreme events. When subjected to adverse events, such as the impact with objects, for example frozen ice chunks referred to as hail during a hail storm, the glass can be forced to flex which may cause multi-axial stresses that may lead to a weakened performance of the solar panel. It would be desirable to provide for an enhanced strength glass to be provided in the vicinity of the cut out holes.SUMMARY

[0004] The problems caused by mechanical processing, including abrasive laser and drill cutting, of one or more holes in a glass sheet can be solved through one or more embodimentsAtorney Docket No.: SP25-024 of the present disclosure, which include heat chamfer processing or plasma torch edge processing of the as-cut edge surface of the glass hole. Heating the edge region of a mechanically processed glass hole to a sufficient temperature removes the damaged portion of the edge or drives surface reflow, which provides an improved and advantaged glass sheet, including at least one or more of the following: smooth edge finish; strengthened edge compared to the as-cut hole; healing of damage and flaws caused by mechanical cut processing; improved handling and installation of the glass sheet, and longer life of the installed glass sheet and the solar panel, among other advantages and improvements as compared to commercially available unprocessed cut glass holes.

[0005] Through one or more embodiments of methods, as described herein, the heat plasma processing enables a heated filament to heat the inner surface of the as-cut hole while the glass sheet is cooled to create a local thermal stress that causes thermal shock to the surface of the glass to removes a surface layer of glass along the edge of the glass hole, thereby resulting in the removal of the defects resulting in an edge finished glass hole.

[0006] Without being bound by a particular mechanism and / or theory, when the surface of the hole in the glass is heated to a very high temperature and the sheet of glass is cooled with a cooling plate, thermal stress results which creates the thermal shock due to the rapid temperature change at the surface of the edge of the hole and creates an exfoliated strip of glass being peeled off the glass surface around the edge of the hole as the heating filament moves in contact with the edge of the hole to encircle the hole. The exfoliated strip of glass contains the cut induced defects which, once removed from the hole, results in a hole with a reduced defect surface that is smooth.

[0007] Through one or more embodiments of methods, as described herein, the plasma torch edge processing enables a plasma plume and / or high-temperature region to cause glass reflow to finish the edge of the glass hole including the inner surface along the edge of the glass holeAtorney Docket No.: SP25-024 while edge-finishing the glass hole. When the glass layer surface along the edge of the hole is sufficiently heated to cause glass reflow, and glass reflow is maintained for a sufficient duration of time, the surface damages in the glass layer of the mechanically processed cut hole in the glass can be reduced and / or eliminated, and the edge surface of the glass hole can become smooth and pristine.

[0008] Without being bound by a particular mechanism and / or theory, when the surface along the edge of the hole in the sheet of glass is heated up to the annealing temperature, then glass reflow occurs and as the glass is heated, the glass surface becomes more viscous. As the glass on the surface of the hole (which has the flaws and / or damage caused by cutting out the hole) becomes more viscous, the glass edge of the hole begins to flow again, which we call the ‘reflow’. As reflow occurs in the glass surface and / or edge region, glass chips and / or shards from cutting migrate and / or remelt with the reflow. With sufficient heating, the surface is fully reflowed, which means at least one of (a) the flaws created by mechanical processing to cut the hole are healed, (b) the glass edge is smoothed, and (c) initiation sites for cracking and defect propagation are healed.

[0009] According to an aspect of the disclosure, a method of forming a hole in a sheet of glass, the method comprising the steps of cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces and treating the edge of the hole with heat to remove defects caused during the cutting of the hole.

[0010] According to another aspect of the disclosure, the step of cutting the hole comprises cutting the hole with a laser or a mechanical drill.

[0011] According to another aspect of the disclosure, the sheet of glass has a thickness in the range of 0.5 mm to 4.0 mm. According to another aspect of the disclosure, the sheet of glass has a thickness in the range of 0.1 mm to 5 mm.Atorney Docket No.: SP25-024

[0012] According to another aspect of the disclosure, the hole in the glass is round.

[0013] According to another aspect of the disclosure, the method further comprises the step of routing one or more electrical leads through the hole and assembling the sheet of glass onto a solar panel.

[0014] According to another aspect of the disclosure, the step of treating the edge of the hole comprises heating the edge of the hole with a heat chamfer process which comprises applying a heating filament to the edge of the hole to remove a portion of the edge within the hole.

[0015] According to another aspect of the disclosure, the method further comprising the step of cooling the sheet of glass with a cooling plate while the heating filament is heating the edge of the hole to cause local thermal stress to remove a surface portion of the edge.

[0016] According to another aspect of the disclosure, the heated filament removes a strip of glass having a thickness of 50 pm-500 pm from the edge.

[0017] According to another aspect of the disclosure, the cooling plate is cooled at an ambient temperature.

[0018] According to another aspect of the disclosure, the heating filament comprises a wire or rod heated to a temperature of at least 1,100 degrees Celsius.

[0019] According to another aspect of the disclosure, the wire or rod is heated to a temperature in the range of about 1,100 degrees Celsius to 1,600 degrees Celsius.

[0020] According to another aspect of the disclosure, the step of treating an edge of the hole comprises treating the edge of the hole with a plasma plume generated by an atmospheric pressure plasma jet.

[0021] According to another aspect of the disclosure, the plasma torch generates a plasma plume at a temperature in the range of 500 degrees Celsius to 1,500 degrees Celsius.

[0022] According to another aspect of the disclosure, the sheet of glass is laminated with another sheet of glass and an encapsulate layer that encapsulates a solar cell.Atorney Docket No.: SP25-024

[0023] According to another aspect of the disclosure, a method of forming a hole in a sheet of glass, the method comprising the steps of: cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces; heating the edge of the hole with a heating filament; moving the heating filament relative to hole to remove a portion of the edge within the hole; and cooling the sheet of glass with a cooling plate while the edge is heated to cause local thermal stress at the edge of the hole to remove a surface portion of the edge.

[0024] According to another aspect of the disclosure, the heating filament comprises a wire or rod heated to a temperature of at least 1,100 degrees Celsius.

[0025] According to another aspect of the disclosure, the wire or rod is heated to a temperature in the range of about 1,100 degrees Celsius to 1,600 degrees Celsius.

[0026] According to another aspect of the disclosure, the heating filament removes a strip of glass having a thickness of 50 pm-500 pm from the edge.

[0027] According to another aspect of the disclosure, the cooling plate is cooled at an ambient temperature.

[0028] According to another aspect of the disclosure, a method of forming a hole in a sheet of glass, the method comprising the steps of: cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces; heating the edge of the hole with a plasma plume generated by a plasma torch; moving the plasma plume relative to hole to reflow a portion of the edge within the hole; and rehealing the reflowed glass to provide a smooth surface on the edge.

[0029] According to another aspect of the disclosure, the plasma torch is an atmospheric pressure plasma jet.

[0030] According to another aspect of the disclosure, the plasma torch generates the plasma plume at a temperature in the range of 500 degrees Celsius to 1,500 degrees Celsius.Atorney Docket No.: SP25-024

[0031] According to another aspect of the disclosure, the sheet of glass has a thickness in the range of 0.5 mm to 4.0 mm.

[0032] According to another aspect of the disclosure, the hole in the glass is round.

[0033] According to another aspect of the disclosure, a glass sheet comprising: a front surface; a back surface; and a cut out glass hole having an edge-finished region extending between the front and back surfaces, wherein the edge-finished region has a smooth profile with no mechanical cutting defects.

[0034] Additional features and advantages 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 as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0035] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the description serve to explain principles and operation of the various embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the Drawings:

[0037] Figure 1 is an upper front perspective view of an arrangement of solar panels, each having front and back sheets of glass and one or more edge-finished holes provided in the back sheet of glass;

[0038] Figure 2 is a rear perspective view of one of the solar panels shown in Figure 1 having an electrical feed cable extending from a hole in the back sheet of glass;Atorney Docket No.: SP25-024

[0039] Figure 3 is a cross-sectional view of a portion of the solar panel taken through line Illi of Figure 2;

[0040] Figure 4 is an upper perspective view of the back sheet of glass illustrating the as-cut hole formed in the sheet of glass with a cutter;

[0041] Figure 5 is an upper perspective view of the back sheet of glass thermally coupled to a cooling plate and undergoing a heat chamfer process to polish the edge of the hole according to a first embodiment;

[0042] Figure 6 is an upper perspective cross-sectional view of the hole taken through line VIVI of Figure 5 during the heat chamfer process;

[0043] Figure 7 is a flow diagram illustrating the method steps for the heat chamfer process according to the first embodiment;

[0044] Figure 8 is an upper perspective view of the sheet of glass with the hole undergoing plasma torch edge processing according to a second embodiment;

[0045] Figure 9 is an upper perspective cross-sectional view of the hole taken through line IX-IX of Figure 8 during the plasma torch edge processing; and

[0046] Figure 10 is a flow diagram illustrating the method steps for the plasma torch edge processing according to the second embodiment.DETAILED DESCRIPTION

[0047] Reference will now be made in detail to the present preferred embodiments, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0048] Referring to Figures 1-4, a solar panel 10 and the formation of one or more cut through holes 30 in a sheet of glass shown and described herein as the back sheet of glass 20 are illustrated. The one or more holes 30 are formed by cutting through-holes extending throughAtorney Docket No.: SP25-024 the entire thickness of the back sheet of glass to allow electrical leads such as wires or cables to pass therethrough to transmit electrical energy from one or more solar cells that are laminated between front and back sheets of glass within the solar cell 26 to a junction box 90 exterior to the sheets of glass. The one or more holes 30 are formed using a mechanical cutting process such that defects such as flaws, chips and cracks, for example, may be present on the edge surface of the hole. These defects are removed by processing the edge of the hole with an edge finishing process using a heat chamfer process according to the first embodiment or a plasma torch edge process according to the second embodiment, as shown and described herein.

[0049] With particular reference to Figure 1, the arrangement of solar panels 10 is illustrated arranged on a mounting structure 12 and oriented to receive sun light energy so that the solar panels 10 operate to convert the sun light energy to electrical energy. As further shown in Figures 2 and 3, each solar panel 10 includes a frame 14 that generally surrounds the peripheral edge of the solar panel 10 and the individual layers therein that are laminated together one in front of the other. The solar panel 10 is a glass-glass solar panel shown having a front sheet of glass 22 and a back sheet of glass 20 and a solar cell 26 encapsulated in an encapsulate layer 24 that is disposed between the front and back sheets of glass 22 and 20. The front side of the front sheet of glass 22 may have a coating 28 to enhance the light reception. The frame 14 may include an edge seal and the frame 14 and seal surround the peripheral edge of each of the laminated front and back sheets of glass 22 and 20, the encapsulate layer 24 and the coating 28.

[0050] The solar panel 10 may be configured with one or more solar cells 26 that may include any solar cell such as solar panels using cSi, CdTe, Perovskite and Tandem solar cell technologies, for example. The solar cell 26 may be encapsulated in the encapsulate layer 24 which may be made of any of polyolefin, silicon and ethylene vinyl acetate (EVA), for example. The solar cell 26 has one or more electrical leads 16 connected to electricalAtorney Docket No.: SP25-024 connections on the solar cell 26. The one or more electrical leads 16 are routed to extend outside the laminated structure of the solar panel 10 to connect with a junction box 90. The one or more electrical leads 16 may include one more wires or cables configured to transport the electrical energy produced by the solar cell 26 to an electrical transmission line or electrical energy storage unit (e.g., battery).

[0051] The front sheet of glass 22 is coated on the front surface with a coating 28 such as a glass metal oxide coating, for example which may serve to enhance light reception directed to the solar cell . The back surface of the front sheet of glass 22 is laminated onto the front surface of the encapsulate layer 24. The back sheet of glass 20 is laminated on the top surface to the back surface of the encapsulate layer 24. The lamination of the front and back sheets of glass 22 and 20 onto the encapsulate layer 24 of the solar panel 10 may be achieved by any of several techniques known to individuals skilled in the art, such as, for example, temperature / vacuum / pressing processes to soften the interlayers and achieve bonding to the glass layers.

[0052] The back sheet of glass 20 is shown and described herein as formed with one or more holes 30 that extend through the thickness of the sheet of glass to allow the one or more electrical leads 16 to extend through the hole 30 and therefore routed out the back side of the solar panel 10. In some embodiments, the front sheet of glass 22 and the back sheet of glass 20 each have a glass composition and may include one or more holes may be cut and processed in either sheet of glass, and hence the processing of the hole is described in connection with a sheet of glass. For example, the glass layers can have a soda lime glass composition, although other glass compositions can be used without limitation, such as aluminosilicate glass compositions and alkali aluminosilicate glass compositions. The glass sheets can be made by a float manufacturing process or a fusion draw manufacturing process. The glass compositionAtorney Docket No.: SP25-024 can be boro-aluminosilicate glass composition, such as alkaline earth boro-aluminosilicate glass composition, or an alkali-free boro-aluminosilicate glass composition.

[0053] The thickness of the sheet of glass or glass layer is the shortest straight-line distance between the front first major surface and the back second major surface of the glass layer. The thickness of the back sheet of glass 20 is 0.1 mm or greater, or 0.2 mm or greater, or 0.5 mm or greater according to various examples. In other examples, the back layer of glass 20 has a thickness in the range of 0.1 mm to 5.0 mm, or 0.5 mm to 4.0 mm, or more particularly in the range of 2.0 mm to 4.0 mm. The back layer of glass 20 is substantially planar with the flat first and second major surfaces on the front and back surfaces that extend in parallel planes. The width and length of the back sheet of glass 20 may vary depending on the size and shape of the solar panel 10. It should be appreciated that while the one or more holes are shown and described herein formed in the back layer of glass 20, the one or more holes could be formed in the front layer of glass 22 according to other examples.

[0054] Prior to laminating the front and back sheets of glass 22 and 20 onto the encapsulate layer 24, the back sheet of glass 20 is processed to cut out the one or more holes 30 and is then further processed to polish the as-cut one or more holes according to one or more of the embodiments shown and described herein. The one or more electrical leads 16 are aligned and positioned to extend within and be routed through the one or more holes 30 and a potting material 35 fills the remainder of each hole 30 to prevent moisture from entering the holes. The individual layers of the solar panel 10 are then laminated together and bounded by the frame 14 on the periphery.

[0055] One example of a cutter 36 cutting a hole 30 through the thickness of the back sheet of glass 20 is illustrated in Figure 4. The cutter 36 may be a laser cutter according to one example or a mechanical drill or grinder according to another example. The cutter 36 removes a layer of glass extending into the thickness of the sheet of glass 20 while moving generally in aAtorney Docket No.: SP25-024 circular path relative to the glass to thereby cut out a cylindrical portion 38 of glass material. With the cut out cylindrical portion 38 removed from the sheet of glass, a rounded hole 30 in a cylindrical shape is formed in the sheet of glass 20 having an edge with inner walls extending from the front surface 32 to the back surface 34 of the sheet of glass 20. The as-cut hole 30 may have a diameter in the range of 6 to 40 mm, for example. It is contemplated that the hole 30 may have other shapes such as an oblong shape, for example. The laser or mechanical cutter 36 is an abrasive form of cutting which inherently damages the surface along the edge of the glass within the hole 30, typically leaving defects such as flaws, chips and cracks in the glass where the hole was cut. The flaws, chips and cracks in the glass are susceptible to further damage when experiencing high stress causing events such as impact with objects such as falling ice chunks or hail during a hail storm which may cause the solar panel and hence the back sheet of glass 20 to flex and thereby cause multi-axial stresses which could decrease the performance or lead to failure of the solar panel 10.

[0056] To enhance the structural integrity of the back sheet of glass 20 with one or more rough cut holes formed therein, a post treatment of the glass hole edge is performed to remove defects, enhance hole edge strength and result in enhanced survivability of abusive conditions such as impact sustained during a hail storm or other abusive condition. The post treatment process involves treating the edge of the hole 30 with high temperature heat to remove the defects in the surface of the glass as the edge of the hole which was created during the abrasive cutting of the hole 30 in the glass sheet. The post treatment process may include a heat chamfer process according to the first embodiment or a plasma torch edge process according to the second embodiment.

[0057] Referring to Figures 5-7, the post treatment process of edge finishing an as-cut hole in a sheet of glass using the heat chamfer process according to the first embodiment is illustrated. The heat chamfer process includes method steps that include the use of a heat chamfer machineAtorney Docket No.: SP25-024 40 to perform the heat chamfer process on the edge forming the inner wall of the hole 30 in the back sheet of glass 20. The heat chamfer machine 40 has a heating filament 42 that is configured to be heated to an elevated temperature and moved in contact along the inner wall surface of the edge of the hole 30. The heat chamfer process also uses a cooling plate 44 in thermal communication with the back sheet of glass 20. The cooling plate 44 may be placed in contact with the back surface of the back sheet of glass 20 to provide thermal conduction to remove heat from the back sheet of glass 20 and thereby cool the sheet of glass. The cooling plate 44 preferably contacts a sufficient surface area of the back sheet of glass 20 to rapidly cool the glass to result in a rapid temperature change along the edge of the hole 30 while the heating filament 42 contacts the surface at the edge of the hole and applies high temperature thermal energy. The rapid temperature change experienced in the glass causes local thermal stress of the surface edge of the hole 30 which causes a thermal shock when the heating filament 42 is applied at a sufficient elevated temperature.

[0058] The heating filament 42 may be configured as an elongated metal rod or wire that is heated to a temperature of 1, 100 degrees Celsius or greater, and preferably in the range of about 1,100 degrees Celsius to 1,600 degrees Celsius, according to one example. The temperature of the heating filament 42 may be in the range of about 1,200 degrees Celsius to about 1,500 degrees Celsius, or in the range of about 1,350 degrees Celsius to 1,450 degrees Celius and more particularly is about 1,400 degrees Celsius according to other examples. The cooling plate 44 may include highly thermal conductive material such as a metal plate body and a carbon plate for contacting the surface of the sheet of glass and may have the shape of a plate with a flat contact surface that conforms to the shape of a portion of the sheet of glass to be contacted so as to enhance the surface area contact between the cooling plate 44 and the sheet of glass 20. The cooling plate 44 is maintained at a temperature that is substantially cooler than the temperature of the heating filament 42 such that a large temperature difference suchAtorney Docket No.: SP25-024 as 1,200 degrees Celsius is provided. The cooling plate 44 in the example shown is a passive cooling plate that may be kept at an ambient room temperature such as 20-30 degrees Celsius, according to one example. The cooling plate 44 may be configured as a loading plate that provides a vacuum holding of the sheet of glass and provides the passive cooling function. According to other examples, the cooling plate 44 may be an active cooling plate cooled to a temperature lower than the ambient room temperature. According to a further embodiment, the cooling plate 44 may thermally cool the back sheet of glass 20 via other forms of heat transfer such as thermal convection.

[0059] Without being bound by a particular mechanism and / or theory, when the edge along the hole 30 in the sheet of glass 20 is heated locally with the heating filament 42 and the glass sheet is simultaneously cooled with the cooling plate 44 as shown in Figures 5 and 6, the thermal shock resulting from the thermal stress created by the rapid temperature change creates an exfoliated edge surface strip 48 as the heating filament 42 moves in contact with the edge and around the inner surface of the edge of the hole 30. The exfoliated edge surface strip 48 peels off the sheet of glass and results in a strip of glass containing the cut induced defects to be removed with the exfoliated edge surface strip 48, thereby leaving a smooth surface 50 along the edge of the hole 30 in the glass. The exfoliated edge surface strip 48 peels off the glass in the form of a strip of glass material from the front corner portion 52 of the hole to the back corner portion 54 of the hole 30 and may have a width in the range of about 50 micrometers (pm) to 500 micrometers (pm), for example, or more particularly in the range of about 200 pm-400 pm. As a result of the removal of this exfoliated edge surface strip 48, an intrinsic clean glass edge surface 50 is exposed along the edge surface of the hole 30 which is substantially free of the defects such as flaws, cracks and chips that may have existed following the cutting of the hole 30 and prior to the post treatment process.Atorney Docket No.: SP25-024

[0060] The method 100 of post treating the cut out hole in the sheet of glass using the heat chamfer process is shown in detailed steps in Figure 7. The heat chamfer method 100 begins at step 102 with the cutting on the hole(s) in the back sheet of glass. Next, the back sheet of glass is placed in thermal communication with the cooling plate at step 104. Proceeding to step 106, method 100 heats an edge portion of the hole with the heated heating filament and moves the heated heating filament relative to the sheet of glass to circle the inner surface edge of the hole while in contact with the edge surface of the glass hole at step 108. The heating filament may contact the edge surface of the hole with constant pressure to ensure a smooth and uniform surface finish. The heated filament may be moved in a circle while contacting the edge of the hole with the glass sheet fixed in place or the glass sheet may be moved in a circle to follow the circular contour of the hole to contact the heating element with the heating filament fixed in place resulting in a vertical cut or peeling of the edge. The exfoliated edge surface that peels off of the edge of the hole of the glass is removed at step 110 to provide an edge-finished glass hole at step 112. Following the heat chamfer method 100, the sheet of glass including the hole may be strengthened using chemical and / or thermal glass strengthening techniques.

[0061] Referring to Figures 8-10, the plasma torch edge processing technique is illustrated for edge finishing an as-cut hole in the sheet of glass according to the second embodiment. The plasma torch edge processing includes treating the as-cut glass hole with a plasma plume 62 generated by a plasma jet 60 such that the inner surface of the edge of the hole 30 and front and back edges of the hole 30 are smooth with a round profile edge. The plasma torch edge processing uses the plasma jet 60 that has the plasma torch 60 that generates the plasma plume 62 which is heated at an elevated temperature sufficient to remelt the edge of the glass along the inner surface and front and back surfaces of the hole 30 in the sheet of glass 20. The remelted edge defines a reflow zone, concomitant with healing at least one defect in the region of the as-cut hole and providing an edge-finished glass hole that has a polished region from theAtorney Docket No.: SP25-024 reflow of the glass and the rehealing, such that any defects including chips, cracks, flaws, and the like are reflowed into the glass edge and healed. In some embodiments, the edge finished region is a fire polished edge.

[0062] The plasma jet 60 is illustrated in Figures 8 and 9 generating a plasma plume 62 directed to contact and heat the inner surface forming the edge of the hole 30 in the sheet of glass 20. In the example shown, the plasma jet 60 is configured as a plasma torch positioned and oriented to direct the plasma plume 62 onto the front edge and inner walls of the hole 30 from the front side at a torch angle relative to an axis orthogonal to the sheet of glass to heat the edge of the hole from the front side. The torch angle is preferably in the range of 30 degrees to 60 degrees, according to one example. According to another example, the torch angle may be in the range of 40 degrees to 50 degrees, and in one specific example, the torch angle may be approximately 45 degrees.

[0063] The sheet of glass 20 is shown in one example supported on a moveable support tray 75 which is configured to be actuated to move the sheet of glass 20 relative to the plasma jet 60 which may remain fixed during the glass plasma heating process. In doing so, the sheet of glass 20 is rotated with the moveable support tray 75 to place the far side of the edge of the hole 30 in direct contact with the plasma plume 62 such that the plasma plume 62 generated by the plasma jet 60 oriented at the torch angle heats the front corner surface and inner wall of the edge of the hole 30. Once the front side of the hole 30 has been plasma heat treated, the sheet of glass 20 on the moveable support tray 75 may be flipped over to allow plasma heat treatment of the back side of the hole 30 which will heat the back comer of the edge and the inner surface of the hole 30 to cause the glass to reflow and reheal to reduce or eliminate defects on both sides of the hole 30. According to another contemplated example, the heat treatment may use a front plasma jet to plasma heat treat the front side of the hole 30 and a second plasma jet on the back side to heat treat the back side of the hole 30 thereby eliminating the need to flip theAtorney Docket No.: SP25-024 sheet of glass over for heating by a single plasma jet. It is also contemplated that the plasma jet 60 may otherwise be configured to be moved to heat the edge of the hole 30 through a circular path while the sheet of glass remains fixed according to other examples.

[0064] With particular reference to Figure 9, the rough cut glass surface 46 of the hole 30 with defects present in the surface of the glass along the edge of the hole 30 is heated to reflow the glass along the edge of the hole and heal the surface on the edge of the hole 30 to form a smooth, polished inner edge surface 50. In addition, the reflow plasma heating process causes both the front comer portion 52 and the back corner portion 54 of the hole 30 to reflow into a rounded edge that is rehealed to form a smooth and polished surface that is substantially free of the as-cut hole defects in the glass.

[0065] The plasma jet 60 may be configured as an atmospheric pressure (AP) plasma jet (APPJ) that operates as a plasma torch at atmospheric pressure in open air environment conditions to generate a plasma plume 62, according to one example. The plasma jet 60 consumes an input gas such as helium or argon that is ionized by a high-voltage electric field that creates the plasma plume 62 which flows through a nozzle at a high temperature. The plasma plume 62 may exhibit temperatures of at least 500 degrees Celsius, or in the range of 500 degrees Celsius to 1,500 degrees Celius, or 750 degrees Celsius to 1,250 degrees Celsius, or 800 degrees Celsius to 1,200 degrees Celsius, for example such that the glass is heated up to the annealing temperature sufficient to cause the surface of the glass to reflow. The plasma jet 60 may include various gases that provide chain reactions such as Nitrogen, for example.

[0066] The plasma torch or jet 60 enables the plasma plume 62 and / or high-temperature region to cause the glass to reflow to finish the surface on the edge of the hole and create smooth rounded front and back comers on the edge of the hole 30. When the glass layer along the surface of the edge of the hole is sufficiently heated to cause reflow, and reflow is maintained for a sufficient duration of time, the surface damage or defects in the glass at the hole 30 canAtorney Docket No.: SP25-024 be reduced and / or eliminated, and the surface of the glass within the hole 30 can become smooth and pristine. When the glass is heated up to the annealing temperature of the glass, then glass reflow may occur and as the glass is heated, the glass surface becomes more viscous. As the glass on the surface at the edge of the hole 30 which has the flaws and / or damages caused by cutting, becomes more viscous, the glass on the surface begins to flow, which is referred to a “reflow”. As the reflow occurs in the glass surface at the edge of the hole, glass chips and / or shards from the cutting migrate and / or remelt with the reflow. With sufficient heating, the surface is fully reflowed, which means at least one of (a) the flaws created by mechanical processing to cut the hole are healed, (b) the glass edge at the hole is smoothed, and (c) initiation sites for cracking and defect propagation are healed.

[0067] The method 200 of post treating the cut out hole 30 in the sheet of glass using the plasma torch edge processing is shown in detailed steps in Figure 8. The plasma torch edge processing method 200 begins at step 202 with the cutting on the hole(s) in the back sheet of glass. The sheet of back glass is thereafter placed on a moveable tray at step 204 and moved relative to the plasma torch in a generally circular path at step 206 to present the plasma plume in contact with the edge of the hole. In doing so, method 200 heats an edge portion and upper and lower corner surfaces of the hole with the plasma torch which is directed onto the hole at an angle. With sufficient heating, the glass remelts to define a reflow zone and heals defects which were present in the edge portion at step 210. Finally, at step 212 an edge-finished glass hole is provided. The sheet of glass with the edge-finished glass hole may then be assembled by lamination onto the other layers of the solar panel and one or more electrical leads may be routed through the hole before completing assembly on the solar panel.

[0068] The methods of forming a hole in a sheet of glass with post hole processing as shown and described herein advantageously provide for a high strength smooth, polished hole in the sheet of glass that is substantially free of the defects that were caused by mechanical cutting ofAtorney Docket No.: SP25-024 the hole, thereby resulting in an enhanced sheet of glass with a hole having a smooth surface profile free of defects and enhance edge strength.

[0069] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claims.

Claims

Atorney Docket No.: SP25-024 In the Claims:What is claimed is:

1. A method of forming a hole in a sheet of glass, the method comprising the steps of:cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces; and treating the edge of the hole with heat to remove defects caused during the cutting of the hole.

2. The method of claim 1, wherein the step of cutting the hole comprises cutting the hole with a laser or a mechanical drill.

3. The method of claim 1 wherein the sheet of glass has a thickness in the range of 0.5 mm to 4.0 mm.

4. The method of claim 1, wherein the hole in the glass is round.

5. The method of claim 1, further comprising the step of routing one or more electrical leads through the hole and assembling the sheet of glass onto a solar panel.

6. The method of claim 1, wherein the step of treating the edge of the hole comprises heating the edge of the hole with a heat chamfer process which comprises applying a heating filament to the edge of the hole to remove a portion of the edge within the hole.Atorney Docket No.: SP25-024 7. The method of claim 6, further comprising the step of cooling the sheet of glass with a cooling plate while the heating filament is heating the edge of the hole to cause local thermal stress to remove a surface portion of the edge.

8. The method of claim 7, wherein the heated filament removes a strip of glass having a thickness of 50 pm-500 pm from the edge.

9. The method of claim 8, wherein the cooling plate is a passive cooling plate cooled at an ambient temperature.

10. The method of claim 7, wherein the heating filament comprises a wire or rod heated to a temperature of at least 1,100 degrees Celsius.

11. The method of claim 8, wherein the wire or rod is heated to a temperature in the range of about 1,110 degrees Celsius to 1,600 degrees Celsius.

12. The method of claim 1, wherein the step of treating an edge of the hole comprises treating the edge of the hole with a plasma plume generated by an atmospheric pressure plasma jet.

13. The method of claim 12, wherein the plasma torch generates a plasma plume at a temperature in the range of 500 degrees Celsius to 1,500 degrees Celsius.

14. The method of claim 12, wherein the sheet of glass is laminated with another sheet of glass and an encapsulate layer that encapsulates a solar cell.Atorney Docket No.: SP25-02415. A method of forming a hole in a sheet of glass, the method comprising the steps of:cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces; heating the edge of the hole with a heating filament;moving the heating filament relative to hole to remove a portion of the edge within the hole; andcooling the sheet of glass with a cooling plate while the edge is heated to cause local thermal stress at the edge of the hole to remove a surface portion of the edge.

16. The method of claim 15, wherein the heating filament comprises a wire or rod heated to a temperature of at least 1,100 degrees Celsius.

17. The method of claim 16, wherein the wire or rod is heated to a temperature in the range of about 1,100 degrees Celsius to 1,600 degrees Celsius.

18. The method of claim 17, wherein the heating filament removes a strip of glass having a thickness of 50 pm-500 pm from the edge.

19. The method of claim 18, wherein the cooling plate is cooled at an ambient temperature.

20. A method of forming a hole in a sheet of glass, the method comprising the steps of:cutting the hole extending through the sheet of glass extending from a front surface to a back surface, the hole having an edge extending between the front and back surfaces;Atorney Docket No.: SP25-024 heating the edge of the hole with a plasma plume generated by a plasma torch; moving the plasma plume relative to hole to reflow a portion of the edge within the hole; andrehealing the reflowed glass to provide a smooth surface on the edge.

21. The method of claim 20, wherein the plasma torch is an atmospheric pressure plasma jet.

22. The method of claim 21, wherein the plasma torch generates the plasma plume at a temperature in the range of 500 degrees Celsius to 1,500 degrees Celsius.

23. The method of claim 20, wherein the sheet of glass has a thickness in the range of 0.5 mm to 4.0 mm.

24. The method of claim 20, wherein the hole in the glass is round.

25. A glass sheet comprising:a front surface;a back surface; anda cut out glass hole having an edge-finished region extending between the front and back surfaces, wherein the edge-finished region has a smooth profile with no mechanical cutting defects.

Images