TW201841857A - Methods and apparatus for finishing edges of glass sheets - Google Patents

Abstract

A method for finishing an edge of a glass sheet comprises grinding the edge of the glass sheet with a grinding wheel. The glass sheet includes a first major surface, a second major surface substantially parallel to the first major surface, and the edge connecting the first and second major surfaces. The grinding produces a central edge portion and two chamfered edge portions connecting the central edge portion with the first and second major surfaces, respectively. The method further comprises polishing the central edge portion with at least one cup wheel rotated about a first axis substantially parallel with the first and second major surfaces of the glass sheet to polish the central edge portion, wherein an abrasive layer of the cup wheel comprises at least one of ferric oxide (Fe2O3), silicon carbide (SiC), and ceric oxide (CeO2).

Description

Method and equipment for refining edge of glass sheet

This case claims the priority of US Provisional Application No. 62 / 449,806 on January 24, 2017. The content of this priority case is incorporated by reference and is hereby incorporated by reference in its entirety.

This disclosure relates to the finishing of glass sheets, and more specifically to methods and equipment for finishing (ie, grinding, polishing, etc.) the edges of glass sheets.

Liquid crystal displays (LCDs) are widely used as display devices for consumer electronics (such as televisions, mobile phones, handheld devices, etc.) due to their small size and outstanding performance with high display resolution. In the LCD, a backlight module is used as a lighting scheme. In other words, the LCD is illuminated by a light source placed behind or at the side of the display panel.

Within the backlight module, a light guide plate (LGP) is used to disperse and guide a one-dimensional light source into two-dimensional uniform light, while requiring very limited space. The necessary conditions for high-quality LGP are high light transmittance and almost no (or no) color shift, among other conditions. LGP can be made of plastic or glass. Among these two common materials, glass has advantages due to, for example, its rigidity and low thermal expansion.

However, for glass sheets that are used as LGPs that are specifically edge-lit LCDs, after the traditional edge finishing process (ie, grinding and polishing of the edges), the glass The level of roughness of the edges of the film and the perpendicularity of the edges have not been optimized. The unoptimized edge properties of the glass sheets affect the light transmittance of the glass sheets. When these glass sheets with non-optimized edge properties are used as LGPs for edge-lit LCD panels, viewers of the LCD panel can observe irregular and / or uneven patterns (such as dots) under certain conditions , Lines, stripes, or any area). This unevenness in the illumination or brightness of the LCD panel is called a Mura defect.

In order to reduce or eliminate Mura defects caused in the manufactured LCD panel, methods and equipment are needed to further improve the process of grinding and polishing glass sheets and to provide improved roughness and perpendicularity of the edges of the glass sheets.

In summary, the present disclosure includes edge finishing equipment and related methods for finishing the edges of glass sheets. The edge finishing device includes a grinding wheel and at least one polishing wheel (such as a cup-shaped wheel), and the rotation axis of the polishing wheel is substantially parallel to the main surface of the processed glass sheet. The grinding surface (or grinding layer) of the cup wheel is disposed on the rim of the cup wheel. This type of grinding wheel exhibits a more uniform abrasion rate over the entire grinding surface than a grinding wheel whose grinding surface is around. The composition of the polishing cup wheel disclosed in this case is also specifically configured to obtain improved polishing efficiency. In addition, the disclosed equipment and methods can help reduce downtime and costs. During the manufacture of the glass sheet, the process of detecting the edge properties is generally performed after the edge finishing process. The use of one or more cup wheels for polishing can help ensure the stable edge quality of the manufactured glass sheet, and the detection process can be omitted or performed only on sampling.

Therefore, the present disclosure discloses a method for refining an edge of a glass sheet, the method comprising: grinding the edge of the glass sheet with a grinding wheel, the glass sheet including a first major surface substantially parallel to the first major surface A second major surface of the surface, and the edge connecting the first and second major surfaces, the grinding step generates a central edge portion and two chamfered edge portions, and the two chamfered edge portions respectively connect the central edge portion with The first and second major surfaces are connected. The method further includes polishing the central edge portion with a first cup-shaped wheel, the first cup-shaped wheel being rotated about a first axis to polish the central edge portion, the first axis being substantially parallel to the glass sheet. The first and second major surfaces, wherein the polishing layer of the first cup wheel includes at least one of iron oxide (Fe ₂ O ₃ ), silicon carbide (SiC), and cerium oxide (CeO ₂ ). The abrasive layer may include Fe ₂ O _{3 in a} volume of about 5% to about 15%. The abrasive layer may contain about 15% to about 27% by volume of SiC or CeO ₂ . The abrasive layer may further include diamond particles including a particle size from about 2 microns to about 4 microns.

In an embodiment, the method further comprises the following steps: conveying at least one of the grinding wheel and the glass sheet such that the relative speed between the grinding wheel and the glass sheet is from about 2 meters per minute to about every minute Within 6 meters. In some embodiments, the method may include: conveying at least one of the first cup-shaped wheel and the glass sheet, such that the relative speed between the first cup-shaped wheel and the glass sheet is from about 4 cm per minute To about 10 meters per minute. The conveying is performed in a direction along a length of the edge of the glass sheet.

The average roughness Ra of the polished central edge portion is equal to or less than about 0.05 micrometers, and the surface energy of the polished central edge portion is within 0.1 perpendicularity with respect to the first or second major surface. The light transmittance through the polished central edge portion in a wavelength range from about 380 nm to about 750 nm is equal to or greater than about 98%, such as across a distance of about 500 mm.

The method may further include performing a middle polishing step on the central edge portion with a second cup-shaped wheel after grinding the edge of the glass sheet but before polishing with the first cup-shaped wheel, wherein the second The cup wheel rotates around a second axis, the second axis being substantially parallel to the first and second major surfaces, and the abrasive particles of the second cup wheel are larger than the abrasive particles of the first cup wheel. The method may include conveying at least one of the second cup-shaped wheel and the glass sheet such that a relative speed between the second cup-shaped wheel and the glass sheet is about 4 meters per minute to about 10 meters per minute In the range. In some embodiments, the second cup wheel can include a plurality of grooves, and the plurality of grooves are distributed along the inner circumference of the abrasive surface of the second cup wheel.

In another embodiment, an apparatus for refining an edge of a glass sheet is described. The apparatus includes: a grinding wheel for grinding the edge of the glass sheet, the glass sheet including a first main A surface, a second major surface substantially parallel to the first major surface, and the edge connecting the first and second major surfaces, the grinding wheel further includes a circumferential groove, and a contour line of the circumferential groove passes through Configured to form a central edge portion and two chamfered edge portions, the central edge portion being substantially perpendicular to the first and second major surfaces, the two chamfered edge portions connecting the central edge portion and the first and second Major surface. The apparatus further includes a first cup wheel for polishing the central edge portion, the first cup wheel being rotatable about a first axis, the first axis being substantially parallel to the first major surface and the second major On the surface, the first cup-shaped wheel includes an abrasive layer including at least one of Fe ₂ O ₃ , SiC, and CeO ₂ .

In some embodiments, the abrasive layer can include about 2 to about 15% Fe ₂ O ₃ by volume. In some embodiments, the abrasive layer can include from about 15% to about 27% by volume of SiC or CeO ₂ . The first cup-shaped wheel contains abrasive particles equal to or greater than about 5000 meshes (5000 #).

In some embodiments, the apparatus may further include a second cup wheel configured to polish the central edge portion, the second cup wheel being supported to be rotatable about a second axis, the second axis being substantially parallel On the first major surface and the second major surface, the abrasive particles of the first cup wheel are smaller than the abrasive particles of the second cup wheel. The second cup-shaped wheel may include a plurality of grooves, and the plurality of grooves are distributed along an inner periphery of one of the grinding surfaces of the second cup-shaped wheel.

The apparatus may further include at least one conveyor coupled to any one of the first cup-shaped wheel and the glass sheet, and the at least one conveyor is configured to be positioned along the edge of the glass sheet. In a length direction, at least one of the first cup-shaped wheel and the glass sheet is conveyed by a relative speed in a range from about 4 meters per minute to about 10 meters per minute.

In yet another embodiment, a glass sheet is described, the glass sheet including edges refined by the apparatus described above, wherein the surface roughness of the central edge portion is less than about 0.05 microns.

In the following embodiments, additional features and advantages will be explained, and part of them will be obvious to those skilled in the art from these descriptions or by implementing the description in this specification (including the following embodiments, patent application scope, and There are accompanying drawings) examples.

It will be understood that the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or structure of the nature and characteristics of the scope of the patent application. The accompanying drawings are incorporated to provide further understanding, and the drawings are incorporated in and constitute a part of this specification. The drawings depict one or more embodiments, and together with the description serve to explain the principles and operations of the various embodiments. It is emphasized that, in accordance with standard practice in the industry, the various characteristics are not drawn to scale. In fact, the dimensions of different characteristics may be arbitrarily increased or decreased for clarity of the discussion.

Reference will now be made in detail to various embodiments of the present application, examples of which are depicted in the accompanying drawings. Where applicable, the same reference symbols will be used throughout the drawings to refer to the same or like parts.

This description will be directed specifically to certain embodiments that form part of (or more directly cooperate with) a device according to the present disclosure. It will be understood that embodiments that are not specifically illustrated or described may take various forms. Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the words "one embodiment" or "one embodiment" appearing in different places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification, the abrasive particle size is referred to by the word "mesh" that follows the number of abrasive particles, or it can be replaced with "#". Therefore, the abrasive grain size of 5000 mesh can also be referred to as 5000 #.

The following description provides a general description of the glass sheet under processing (more specifically, edge finishing) by the apparatus and / or method of the present disclosure.

After a glass sheet is formed (eg, by scoring or cutting a glass ribbon or another glass sheet), the edge surface of the glass sheet may require further processing to achieve the desired edge surface finish. Therefore, FIG. 1 schematically depicts a method 100 for processing the edge of a glass sheet. According to FIG. 1, in a first step 102, a grinding wheel is used to grind the edge of the glass sheet. In one or more subsequent steps, polishing is performed by one or more polishing wheels. For example, in the selective rough polishing step 104, a first rough polishing wheel may be used to polish the ground edges of the glass sheet. Alternatively, in some embodiments, polishing may be performed directly from grinding to the fine polishing step 106 without the need for a coarse polishing step 104. Both rough polishing and fine polishing can be performed using a cup wheel, which will be described in more detail below.

1A to 1C are schematic views of the glass sheet 200 described in the present application. The glass sheet 200 includes a first major surface 202, a second major surface 204 substantially parallel to the first major surface 202, and an edge surface (or simply "edge") connecting the first and second major surfaces 202, 204. 206 and 208. The distance between the first and second major surfaces 202, 204 (also the height of the edge surfaces 206 and 208) defines the thickness T of the glass sheet 200. During the manufacturing process, the glass sheet 200 may be conveyed in a conveying direction 210. Although the edge surfaces 206 and 208 are shown as flat in the FIGS. 1A to 1C, it should be noted that the edge surfaces 206 and 208 may include other shapes in further embodiments. For example, in some embodiments, the edge surface 206 and / or the edge surface 208 may include a chamfered surface or a rounded surface (eg, a result of a previous grinding and / or polishing operation).

In various embodiments of the present disclosure, the thickness of the glass sheet 200 may be in the following ranges: from about 100 m to about 3 mm, from about 300 m to about 3 mm, from about 400 m to about 2 mm, from About 0.5 mm to about 1 mm, or from about 0.5 mm to about 0.7 mm, including all ranges and sub-ranges between the above, without departing from the scope of the present disclosure.

The glass sheet 200 can be positioned such that the first and second major surfaces 202, 204 are parallel to a horizontal plane. However, it should be understood that such an arrangement is not a necessary condition for any embodiment of the present disclosure, and the scope of the claimed subject matter is not limited thereto. Therefore, the glass sheet 200 may be arranged in other planes, such as a vertical plane, or any other plane between the horizontal and vertical planes.

In FIGS. 2A to 2C, the glass sheet 200 can be conveyed in the conveying direction 210 by any appropriate conveyer (not shown). It should be understood that according to the foregoing, the glass sheets 200 can be placed in different arrangement orientations, and the conveying direction 210 can be different based on the needs of different processes. It should also be understood that in more embodiments, the glass sheet 200 may be fixed in a position. Further, although the embodiments described in this specification are directed to glass sheets having a rectangular shape, it should be understood that glass sheets can be processed in many different shapes.

Embodiments of the present disclosure include an edge finishing device for processing one or more edges of a glass sheet, the edge finishing device including a grinding wheel 300 for grinding the edges of the glass sheet 200. FIG. 3A schematically depicts an exemplary grinding wheel 300 and a portion of a glass sheet 200.

The grinding wheel 300 includes a circumferential groove 302 located around the grinding wheel, and the circumferential groove 302 includes a grinding surface. The circumferential groove 302 may have a contour line configured to shape an edge of the glass sheet into any desired edge contour line. For example, in some embodiments, the circumferential groove 302 can include two turning sections 304 and 306 and a middle section 308, which are configured to produce chamfered edges (eg, edges 206) of the glass sheet 200 surface.

During grinding, the grinding wheel 300 is rotated around a central rotation axis 310 at a predetermined rotation speed. The rotation speed may be at least 3,600 revolutions per minute (rpm) to efficiently grind an edge surface (such as the surface of edge 206) of glass sheet 200, such as in a range from about 3,600 rpm to about 6,000 rpm. The grinding wheel 300 may be supported and rotated by a mandrel coupled to a motor. It can be rotated clockwise or counterclockwise.

The grinding wheel 300 may be positioned so that the rotation axis 310 is substantially parallel to the normals of the first and second major surfaces 202 and 204 of the glass sheet 200. Furthermore, the grinding wheel 300 and the glass sheet 200 can be aligned relative to each other so that a median plane that crosses the edge 206 in a direction parallel to the first and second major surfaces 202 and 204 passes through the middle section 308 of the grinding wheel 300. The middle point extends.

In some embodiments, the glass may be conveyed in the conveying direction 210 during grinding by any suitable conveyor (not shown) in a direction along a length of the edge surface 206 (ie, from the page outwards as in FIG. 3A). Sheet 200, and the grinding wheel 300 of the edge finishing device may be fixed at a position adjacent to the conveyance path of the glass sheet 200. In other embodiments, the grinding wheel 300 can be moved along the length of an edge (such as the edge surface 206) of the glass sheet 200 by another conveyor (not shown) while the glass sheet 200 is in a fixed position. In more embodiments, both the glass sheet 200 and the grinding wheel 300 can move in the opposite direction along the length of the edge surface 206. The relative speed between the grinding wheel 300 and the glass sheet 200 can range from about 2 meters per minute to about 6 meters per minute.

As the edge surface 206 of the glass sheet 200 is ground by the grinding wheel 300, different sections 304, 306, and 308 of the circumferential groove 302 can shape the edge surface 206 to be substantially perpendicular to the first and second major surfaces 202 and 204. A central edge portion 212 and two chamfered edge portions 214 and 216 of the two are schematically illustrated in FIG. 3B (not shown to scale).

The two chamfered edge portions 214 and 216 connect the central edge portion 212 with the first main surface 202 and the second main surface 204, respectively. By chamfering the edge 200 of the glass sheet, breakage or chipping of the glass sheet, such as during subsequent processing (eg, when the glass sheet 200 is transferred to a subsequent processing step or station, packaging, or transported) can be avoided.

As shown in Figure 3B, the chamfered edge portion 214 (216) contains the chamfered height, which is marked as "C". Preferably, the chamfered heights C of the chamfered edge portions 214 and 216 are equal, but the individual chamfered heights may be different in more embodiments. It will be understood that the chamfer height C should be as small as possible, because the central edge portion 212 contributes to the overall optical quality of the glass sheet 200 (especially when used as a side-light type light guide plate in a backlight unit). Non-chamfered edge portions 214 and 216. More specifically, it has been found that a better measurement result is obtained for the light transmittance of the edge 200 of the glass sheet when the central edge portion 212 includes most of the thickness of the glass sheet 200. In some embodiments where the thickness T of the glass sheet 200 is approximately 2.0 mm, the chamfer height C obtained from the grinding process is less than 0.2 mm. In other embodiments where the thickness T of the glass sheet 200 is about 0.7 mm, the chamfer height C obtained from the grinding process is in a range of about 0.02 mm to about 0.08 mm.

After grinding by the grinding wheel 300, the generated central edge portion 212 may be substantially perpendicular to the first major surface 202 and the second major surface 204 of the glass sheet 200. However, the central edge portion 212 may still show a small difference from vertical. FIG. 3C is an enlarged and exaggerated view of a portion of the center edge portion 212 after grinding. For comparison, a straight line 312 perpendicular to the first major surface 202 and the second major surface 204 is illustrated. The surface of the central edge portion 212 and the straight line 312 form an angle θ. In an embodiment of the present disclosure, the angle θ after grinding the edge surface 206 with the grinding wheel 300 may be in a range of about -2 to about +2 degrees.

Furthermore, the roughness of the surface of the central edge portion 212 after grinding by the grinding wheel 300 may be greater than that of the edge surface 206 before grinding. As described in this specification, roughness is measured as the arithmetic average roughness of a surface (hereinafter referred to as "Ra"). In the embodiment of the present disclosure, the Ra value of the central edge portion 212 after grinding but before polishing may be about 0.5 μm. The roughness of the polished edge surface affects the light transmittance, and the measured light transmittance through the central edge portion 212 after grinding is only about 2%. According to this, the glass sheet 200 may not be suitable as a light guide plate in a backlight unit (and is particularly used for a light guide plate intended to be lit from its edge) when it is only subjected to grinding.

Because grinding alone is not sufficient to provide the ideal glass sheet edge 200, the edge finishing device for processing glass sheets described in this specification may further include one or more polishing wheels for use after grinding by the grinding wheel 300 Polished edges such as one or more cup wheels. Accordingly, the process 100 may include a selective intermediate polishing step 104 and a fine polishing step 106.

FIG. 3A is a cross-sectional view of an exemplary cup wheel 400 suitable for use with the edge finishing device of the present disclosure. The cross-sectional view of FIG. 3A is taken along the center rotation axis 402 of the cup wheel 400, and the cup wheel 400 is rotated about the center rotation axis.

The cup wheel 400 includes a base portion 404 and an annular portion 406 integrated with the base portion 404. The base portion 404 may be a circular flat plate, and the annular portion 406 may be integrated into the base portion 404 around the outer periphery of the base portion 404.

The annular portion 406 includes a substantially annular abrasive layer 408 which is concentric with the rotation axis 402 and is disposed on a surface of the annular portion 406 opposite to the base portion 404. The polishing layer 408 includes abrasive particles for polishing, and may further include other materials to enhance the polishing effect. The surface of the polishing layer 408 is substantially flat.

In the embodiment of the present disclosure, the thickness (height) of the abrasive layer 408 may be in a range of about 2 mm to about 7 mm (for example, about 5 mm), but the thickness of the layer 408 is not limited thereto and may be other thicknesses.

The annular portion 406 is depicted as a hollow cylinder in Figure 4A. It should be understood that the annular portion 406 of the cup-shaped wheel 400 may be other shapes without departing from the scope of the present disclosure. For example, the outer diameter of the annular portion 406 may be tapered or diverged from one end to the other.

In an embodiment in which the annular portion 406 of the cup-shaped wheel 400 includes a hollow cylindrical shape, the width W (and the width of the annular abrasive layer 408) of the annular portion 406 may be, for example, in a range of about 10 mm to about 20 mm, For example, a range from about 12 mm to about 15 mm, but other values of the width W of the annular portion 406 are also conceivable. However, as will be explained below, the width W of the annular portion 406 (ie, the width of the wall of the annular portion) is preferably larger than the thickness T of the glass sheet 200 to be polished. In addition, the width W of the annular portion 406 should be large enough to allow the annular portion 406 to be efficiently and stably mounted on the base portion 404. FIG. 3B is a perspective view of the cup wheel 400 of FIG. 3A shown as being engaged with the glass sheet 200.

During polishing, the cup wheel 400 rotates around the rotation shaft 402 at a rotation speed in a range of about 3,600 rpm to about 6,000 rpm. Rotation can be done in a clockwise or counterclockwise direction. The cup wheel 400 may be supported and rotated by a mandrel coupled to a motor.

The cup-shaped wheel 400 can be positioned such that the rotation axis 402 is parallel to the first and second major surfaces 204, 206 of the glass sheet 200 so that the abrasive layer 408 contacts the central edge portion 212 of the glass sheet 200.

In some embodiments, during polishing, the glass sheet 200 is conveyed by a conveyor (not shown) in a conveying direction 210 along a length of the central edge portion 212 (ie, from the page outwards as shown in FIG. 4B), and the cup The profile wheel 400 is fixed at a position beside the conveyance path of the glass sheet 200. In other embodiments, another conveyor (not shown) can be used to move the cup-shaped wheel 400 of the edge finishing device along the length of the edge surface (such as the central edge portion 212) of the processed glass sheet 200, while the glass The sheet 200 is in a fixed position. In more embodiments, both the glass sheet 200 and the cup-shaped wheel 400 can move at a relative speed in the opposite direction along the length of the central edge portion 212. In some embodiments, the relative speed between the cup wheel 400 and the glass sheet 200 of the edge finishing device can be in a range of about 4 meters per minute to about 10 meters per minute.

The type of wheel where the grinding surface is around the wheel and is rotated about an axis approximately perpendicular to the main surface of the glass sheet, such as grinding wheel 300 depicted in Figure 3A, there may be fewer parts of the grinding surface than the rest of the grinding surface Faster wear, as points along the edge of the glass sheet touch only a corresponding circumference of the grinding wheel while the grinding wheel rotates. On the other hand, the grinding surface of a cup wheel (such as cup wheel 400) can exhibit a slower wear rate because the area of the grinding surface that is contacted by a workpiece (such as glass sheet 200) during polishing contains a larger portion of the grinding surface . Furthermore, since the rotation axis of the cup-shaped wheel is approximately parallel to the glass sheet 200, the wear of the cup-shaped wheel is evenly distributed over the entire surface of the polishing layer 208, and thus the life of the cup-shaped wheel can be extended.

In some embodiments, the polishing cup wheel may include a grooved cup wheel, such as the cup wheel 500 illustrated in FIG. 5. In some embodiments, the cup-shaped wheel 500 with grooves may be the same as the cup-shaped wheel 400, except that the cup-shaped wheel 500 is formed with a plurality of grooves 502, which are substantially radially and evenly distributed on the The entire outer surface of the polishing layer 508 is polished. In some embodiments, the grooves 502 are evenly distributed on the inner periphery of the abrasive layer 508. In some embodiments, the abrasive layer 508 may include about 20 grooves to about 30 grooves. In some embodiments, the groove width may be about 3 mm to about 4 mm. The grooves may be arranged, for example, at an angle of about 40 ° to about 50 ° with respect to the diameter of the cup wheel 500.

The groove 502 can be effective in dissipating heat generated during polishing. The groove 502 can also provide a greater grinding efficiency for the grooved cup wheel 500 than the cup wheel 200 depicted in Figures 3A and 3B, because the groove can help remove more material from the glass sheet during polishing .

Although the grooves 502 are depicted as a uniform stripe shape in FIG. 4, other shapes and arrangements of the grooves 502 may be used.

In the embodiment of the present disclosure, the composition of the polishing layers 408 and 508 may include a material for enhancing polishing. Table 1 lists exemplary compositions of the abrasive layers 408, 508 of the cup wheels 400, 500 according to some embodiments. Table 1

In the embodiment of the present disclosure, the grinding layers 408 and 508 of the cup wheels 400 and 500 can include cerium oxide (CeO ₂ ), silicon carbide (SiC), and / or iron oxide (Fe ₂ O ₃ ) as an improved polishing efficiency Polishing media. In some embodiments, the abrasive layers 408, 508 can include Fe ₂ O _{3 in a} volume of about 5% to 15%. In some embodiments, the polishing layers 408, 508 include at least one of CeO ₂ and SiC, occupying about 15% to about 27% of the volume.

The abrasive layers 408, 508 may also include copper (Cu) to promote heat dissipation, for example in the range of about 20% to 50% by volume. For example, in some embodiments, a cup wheel designated for fine polishing (ie, the fine polishing step 106) may contain Cu in an amount of about 40% to about 50% by volume, while being designated for rough grinding ( That is, the cup wheel of the rough polishing step 104) may contain an amount of Cu from about 20% to about 40%.

In some embodiments, the cup wheels 400, 500 may include diamond particles, wherein the average particle size may range from about 2 microns to about 8 microns, such as a range from about 2 microns to about 6 microns, such as from about 2 microns to about 4 A range of micrometers, such as a range of about 6 micrometers to about 8 micrometers. The amount of diamond particles may be in the range of about 0.5% to about 1.5% by volume. Typically, a finely polished cup wheel contains diamond particles having an average particle size in a range from about 2 microns to about 4 microns, while a coarsely polished cup wheel contains an average particle size of about 6 Diamond particles in the range of microns to about 8 microns, although other average particle sizes can be used in more embodiments.

In an embodiment, the cup wheels 400 and 500 may be resin bonding wheels, and the abrasive layers 408 and 508 may include a resin bonding agent in an amount of about 20% to about 40% by volume. The resin mixed with the abrasive material is used as a bonding material to keep the abrasive material positioned in the abrasive layer together. Other adhesive materials suitable for retaining the above-mentioned abrasive materials are conceivable. Generally, the amount of epoxy resin contained in the fine-polished cup wheel is from about 30% to about 40% by volume, while the amount of the epoxy resin that can be contained in the coarse-polished cup wheel is about 30% to about 30% by volume. Volume, although other epoxy volume can be used in more embodiments.

As described above, in some embodiments, the edge processing method 100 includes a grinding step 102 using a grinding wheel 300 (as described above), followed by a polishing step. For example, the edge processing method 100 may include a grinding step 102 and a fine polishing step by a fine polishing wheel, such as a cup-shaped wheel 400. During the grinding step 102, the edge surface 206 of the glass sheet 200 is ground by the circumferential groove 302 of the grinding wheel 300. The grinding wheel 300 is rotated about a rotation axis 310 substantially parallel to a normal line of the first and second major surfaces 202 and 204. This grinding step produces a central edge portion 212 and two chamfered edge portions 214, 216, which connect the central edge portion 212 with the first major surface 202 and the second major surface 204. The central edge portion 212 is substantially perpendicular to both the first and second major surfaces 202, 204.

To provide improved verticality and smoothness of the center edge portion 212, in some embodiments, a fine polishing step may be performed using the cup wheel 400 immediately after the grinding step to produce a polished center edge portion 212. The cup wheel 400 is rotated about an axis substantially parallel to both the first and second major surfaces 202, 204 of the glass sheet 200.

In more embodiments, the edge processing method 100 may also include an intermediate polishing step 104 after the grinding step 102 but before the fine polishing step 106, such as using a cup-shaped wheel 500. Accordingly, during step 104, the second cup-shaped wheel may be used to rough polish the ground central edge portion 212 to produce a smoother polished central edge portion. The coarse polishing cup wheel used during step 104 contains larger abrasive grains than the fine polishing cup wheel used during step 106. Both the rough polishing cup wheel and the fine polishing cup wheel during the selective rough polishing step 104 and the fine polishing step 106 rotate about a rotation axis substantially parallel to both the first and second major surfaces 202, 204.

The difference between a fine polishing wheel (such as a cup wheel 400) and a coarse polishing wheel (such as a cup wheel 500) is at least the particle size of the abrasive particles. In other words, in embodiments where the edge finishing device includes two (or even more) cup wheels for polishing the edges of a glass sheet, the two cup wheels may have abrasive grains of different particle sizes.

The size of the abrasive particles of the grinding wheel is usually measured by the "mesh number", which represents the number of holes per square inch of the screen used for the abrasive particles. In the embodiment of the present disclosure, the grinding wheel (eg, grinding wheel 300) of the edge finishing equipment may be 800 mesh or 1200 mesh, and the cup wheel used during the rough polishing process or the fine polishing process is 2000 Meshes, 3000 meshes, 5000 meshes, 6000 meshes, and 9,000 meshes. Commonly, fine polishing cup wheels contain abrasive particles equal to or greater than about 5,000 meshes, such as in the range of about 5000 meshes to about 9,000 meshes, such as in the range of about 5000 meshes to about 8,000 meshes, such as In the range of 5000 mesh to about 7000 mesh, or in the range of about 5000 mesh to about 6000 mesh.

In addition, the cup-shaped wheel 500 tends to produce more positive polishing results, removing more material than a non-grooved polishing wheel, and therefore the grooved cup-wheel 500 is needed more during the intermediate polishing step 104.

It is understood that steps 102, 104, and 106 can be repeated as many times as needed.

It is also understood that multiple grinding and / or polishing wheels may be operated simultaneously in some embodiments. For example, in some embodiments there may be two grinding wheels in the edge finishing device, each grinding wheel grinding the opposite edge of the glass sheet simultaneously. Examples

The following Tables 2 to 6 disclose example configurations in different embodiments of the present disclosure. The average roughness Ra and light transmittance measured for the edges refined by the apparatus and / or method of the present disclosure are also disclosed. All roughness values were obtained using a Keyance VK-850 3D laser scanning confocal microscope.

Among these parameters, the value in the "Grinding wheel type" column refers to the particle size of the wheel and its abrasive grains (in mesh), where "G" indicates the type of the grinding wheel, ""C" indicates a cup-shaped wheel (eg, cup-shaped wheel 400), and "S" indicates a grooved cup-shaped wheel (eg, cup-shaped wheel 500). The parameter "conveying speed" refers to the relative speed between the glass sheet and the edge finishing equipment. The parameter "amount removed" refers to the amount of glass pieces removed by the individual grinding and / or polishing wheels of the edge finishing equipment. Table 2 Table 3 Table 4 Table 5

According to the example described in this disclosure, the arithmetic average roughness (Ra) of the edge surface (such as the central edge portion 212 in FIG. 3B) after being ground by the grinding wheel 300 is about 0.5 μm. The finished edge surface (such as the central edge portion 212) after being processed by the edge finishing equipment (for example, after the fine polishing step 106 and the selective intermediate polishing step 104) contains a Ra value equal to or less than about 0.05 μm.

What's more, the finished edge surface can be approximately perpendicular to the main surface of the glass sheet, with a difference of only 0.1 degree. That is, for the central edge portion 212 processed by the edge finishing device, the value of the angle θ indicated in FIG. 3C is in the range of -0.1 to 0.1 degrees. As the roughness level improves, the light transmittance of the edges refined by the edge finishing equipment and method in this specification can reach more than 98%.

The improved light transmittance achieved by employing the embodiments discussed in this disclosure for edges reduces the occurrence of variations in lighting of the display panel (known as Mura defects).

It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit or scope of the subject matter requested.

100‧‧‧ Method

Steps 102, 104, 106‧‧‧

200‧‧‧ glass

202‧‧‧First major surface

204‧‧‧Second major surface

206, 208‧‧‧Edge surface

210‧‧‧ Conveying direction

212‧‧‧Central edge section

214, 216‧‧‧ chamfered edges

300‧‧‧ grinding wheel

302‧‧‧Circular groove

304, 306‧‧‧turning section

308‧‧‧Mid

310‧‧‧center rotation axis

312‧‧‧Straight

400‧‧‧ cup round

402‧‧‧rotation axis

404‧‧‧ base

406‧‧‧Ring

408‧‧‧abrasive layer

500‧‧‧ cup round

502‧‧‧Groove

508‧‧‧ abrasive layer

C‧‧‧Chamfer height

T‧‧‧ glass thickness

W‧‧‧Width

FIG. 1 is a flowchart of an exemplary process for refining a glass sheet edge according to an embodiment of the present disclosure;

Figure 2A is a top view of an exemplary glass sheet;

Figure 2B is a side view of the glass sheet of Figure 2A;

Figure 2C is a perspective view of the glass sheet of Figure 2A;

Figure 3A is a side view of an exemplary grinding wheel for refining a glass sheet according to an embodiment of the present disclosure;

Figure 3B is a side (edge) view of the glass sheet of Figure 2A after being treated by the grinding wheel of Figure 3A;

Figure 3C is a partially enlarged view of the glass sheet of Figure 3B;

4A is a cross-sectional view of a cup-shaped wheel of an edge finishing device according to some embodiments of the present disclosure;

Fig. 4B schematically depicts the cup-shaped wheel of Fig. 4A which is processing a glass sheet; and

FIG. 5 is a perspective view of an alternative cup wheel of an edge finishing device according to a further embodiment of the present disclosure.

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Claims (10)

A method for refining an edge of a glass sheet, the method comprising the following steps: grinding the edge of the glass sheet with a grinding wheel, the glass sheet including a first major surface, substantially parallel to the first major surface; A second major surface and the edge connecting the first and second major surfaces, the grinding step generates a central edge portion and two chamfered edge portions, and the two chamfered edge portions respectively connect the central edge portion with The first and second major surfaces are connected; and a first cup-shaped wheel is used to polish the central edge portion, and the first cup-shaped wheel is rotated about a first axis to polish the central edge portion, the first axis being approximately Parallel to the first and second major surfaces of the glass sheet, wherein the grinding layer of the cup wheel includes at least one of iron oxide (Fe ₂ O ₃ ), silicon carbide (SiC), and cerium oxide (CeO ₂ ) . The method of claim 1, wherein the abrasive layer comprises Fe ₂ O _{3 in a} volume of about 5% to about 15%. The method of claim 1, wherein the abrasive layer comprises SiC or CeO _{2 in a} volume of about 15% to about 27% by volume. The method of claim 1, wherein the abrasive layer further comprises diamond particles, the diamond particles having a particle size of from 2 μm to 4 μm. The method according to claim 1, further comprising the step of: after grinding the edge of the glass sheet, performing a middle polishing on the central edge portion with a second cup wheel, the second cup wheel being surrounded by a first Two-axis rotation, the second axis is substantially parallel to the first and second major surfaces, and the abrasive particles of the second cup wheel are larger than the abrasive particles of the first cup wheel. The method of claim 5, wherein the second cup-shaped wheel includes a plurality of grooves, and the plurality of grooves are distributed along an inner periphery of one of the abrasive surfaces of the second cup-shaped wheel. A device for refining an edge of a glass sheet, the device comprising: a grinding wheel for grinding the edge of the glass sheet, the glass sheet including a first major surface, substantially parallel to the first A second major surface of the main surface and the edge connecting the first and second major surfaces, the grinding wheel further includes a circumferential groove, and a contour line of the circumferential groove is configured to form a central edge portion and Two chamfered edge portions, the central edge portion being substantially perpendicular to the first and second major surfaces, the two chamfered edge portions connecting the central edge portion and the first and second major surfaces; and a cup-shaped wheel, the cup A profile wheel is used to polish the central edge portion. The cup profile wheel can be rotated around a first axis, the first axis being substantially parallel to the first and second major surfaces of the glass sheet. The cup profile wheel includes a grinding The polishing layer includes at least one of iron oxide (Fe ₂ O ₃ ), silicon carbide (SiC), and cerium oxide (CeO ₂ ). The apparatus according to claim 7, further comprising a second cup wheel configured to polish the central edge portion, the second cup wheel being supported and rotating about a second axis, the The second axis is substantially parallel to the first and second major surfaces, wherein the abrasive particles of the first cup-shaped wheel are smaller than the abrasive particles of the second cup-shaped wheel. The apparatus according to claim 8, wherein the second cup wheel comprises a plurality of grooves, and the plurality of grooves are distributed along an inner circumference of one of the grinding surfaces of the second cup wheel. A glass sheet comprising an edge refined by the device according to any one of claims 8 to 9, wherein the surface roughness of the central edge portion is less than 0.05 micrometer.