JP6624461B2 - Glass sheet chamfering apparatus, glass sheet chamfering method, and glass sheet manufacturing method - Google Patents

Description

  The present invention relates to a glass sheet chamfering apparatus, a glass sheet chamfering method, and a method for manufacturing a glass sheet.

  Glass plates for FPD (Flat Panel Display) used for liquid crystal displays, plasma displays, etc. are formed by a process of forming molten glass into a band-shaped plate glass (also referred to as a glass ribbon), and a glass plate having a predetermined rectangular size. It is manufactured by passing through a cutting step of cutting into a plate and a chamfering step of grinding and polishing the end surface of the glass plate.

  Patent Document 1 discloses a chamfering device used in the chamfering step.

  In the chamfering device of Patent Document 1, a glass plate (work) held by holding means is transported by a transport mechanism to a position where a primary end face grinding unit is installed, and grinding processing is performed on both end faces. . Next, the glass sheet is transported to a position where the secondary end surface grinding unit is installed, and the grinding process is performed on both end surface portions. Patent Document 1 also discloses that an end surface polishing unit is provided on the downstream side in the transport direction of the glass plate in order to perform mirror finishing on the end surface of the glass plate.

  On the other hand, the chamfering device described in Patent Literature 2 includes a metal bond grindstone having a V-shaped groove for grinding on an outer peripheral surface, and an elastic grindstone having a flat outer peripheral surface serving as a polishing surface. According to the chamfering device of Patent Document 2, the end face of the glass plate is ground by the V-shaped groove of the metal bond grindstone to form a chamfered face on the end face, and then the chamfered face is formed by the flat outer peripheral surface of the elastic grindstone. Grind.

JP 2013-198974 A JP 2001-9689 A

  By the way, recently, as the definition of a liquid crystal display has become higher, quality requirements for fine dust (also referred to as particles) attached to the surface of a glass plate have been increasing. That is, fine dust becomes foreign matter when elements such as electrodes are formed on the surface of the glass plate.

  From this, it has been found that fine cullet generated from the chamfered surface (end surface) of the glass plate also affects the quality of the glass plate, and thus further improvement in the glass plate chamfering technology. It has been desired.

  The conventional chamfering devices disclosed in Patent Literatures 1 and 2 dispose two grindstones on one end face of a glass plate, grind the end faces into a desired chamfered shape with a preceding grindstone, and use a subsequent grindstone. The end face is polished.

  However, it has been difficult to reliably polish and remove relatively large chippings and cracks (chips) generated on the end face by the front-stage grindstone only with the rear-stage grindstone. That is, it was difficult to machine the chamfered surface to a mirror surface that does not generate cullet by using only the grinding wheel in the latter stage.

  As a result, the conventional chamfering apparatus has a problem that it is difficult to perform chamfering to the specifications accompanying the recent high definition of the liquid crystal display.

  It is also conceivable to arrange four grindstones having different grinding capabilities, that is, four grindstones having different performances, so that rough grinding, medium grinding, finishing, and mirror finishing can be sequentially performed on the end surface of the glass sheet. However, in this chamfering device, the number of rotating devices is increased by the amount of the grindstone, so that the device configuration becomes complicated, which is not preferable.

  The present invention has been made in view of such circumstances, and without increasing the number of whetstones, a glass sheet chamfering apparatus, a glass sheet chamfering method, and a glass sheet capable of improving the glass sheet chamfering quality. An object of the present invention is to provide a method for manufacturing a board.

The glass sheet chamfering device of the present invention, in order to achieve the above object,
With a whetstone,
Rotating means for rotating the whetstone about its central axis, and first moving means for relatively moving the whetstone and the glass plate along a first direction orthogonal to an end face of the glass plate,
A second moving unit that relatively reciprocates the grindstone and the glass plate along a second direction in which the end surface of the glass plate extends, and grinds the same end surface of the glass plate a plurality of times,
Third moving means for relatively moving the grinding stone and the glass plate along a main surface of the glass plate and a third direction orthogonal to the second direction;
Control means for controlling the first moving means, the second moving means, and the third moving means;
It is characterized by having.

The glass plate chamfering method of the present invention, in order to achieve the above object,
The grindstone is composed of upper and lower divided grindstone portions, and after pressing one of the upper and lower divided grindstone portions against one end surface of a glass plate, the grindstone and the glass plate are separated from each other by the one-piece. A first grinding step of relatively moving the end face in one extending direction, and grinding the one end face by rotating the one split whetstone part around its central axis;
After pressing the other divided whetstone part of the upper and lower divided whetstone parts against the one end surface of the glass plate, the whetstone and the glass plate are moved in the other extending direction of the one end surface or one of the two. A second grinding step of relatively moving in the extending direction, and grinding the same one end face by rotating the other divided whetstone portion about its central axis,
It is characterized by having.

  In order to achieve the above object, the method for producing a glass sheet of the present invention includes a melting step of heating a glass raw material to obtain a molten glass; a forming step of forming the molten glass into a plate to obtain a glass ribbon; The method includes a cutting step of cutting a ribbon to obtain a glass sheet, and a chamfering step of chamfering the glass sheet by the chamfering method of the glass sheet.

  In one aspect of the glass plate chamfering apparatus of the present invention, the whetstone includes at least a first whetstone and a second whetstone, and the first whetstone and the second whetstone are configured in a columnar shape. It is preferable that at least two divided grindstone portions are divided in the axial direction, and that one of the divided grindstone portions has a higher grinding ability than the other divided grindstone portion.

One embodiment of the glass plate chamfering method of the present invention,
The grindstone is composed of at least a first grindstone and a second grindstone,
The first grindstone and the second grindstone are formed in a columnar shape and are axially divided into at least two or more divided grindstone portions, and the grinding ability of one of the divided grindstone portions is divided. It is higher than the grinding capacity of the other split whetstone part,
After pressing one of the divided whetstone portions having a high grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A first chamfering step of grinding the one end face by rotating the first grindstone around its central axis,
After pressing one of the divided whetstone portions having a high grinding ability of the second whetstone against one end surface of the glass plate, the second whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A second chamfering step of grinding the one end face by rotating the second grindstone about its central axis,
After pressing the other divided whetstone part having a low grinding ability of the second whetstone against one end surface of the glass plate, the second whetstone and the glass plate are moved in the other extending direction of the one end surface. A third chamfering step of relatively moving and grinding the one end face by rotating the second grindstone about its central axis;
After pressing the other split whetstone part having a low grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are moved in the other extending direction of the one end surface. A fourth chamfering step of relatively moving and grinding the one end face by rotating the first grindstone about its central axis;
It is preferable to provide

  In one aspect of the glass plate chamfering apparatus of the present invention, the whetstone includes at least a first whetstone and a second whetstone, and the first whetstone is formed in a columnar shape and has at least two wedges in an axial direction. The grinding ability of one of the divided whetstone parts divided into two or more divided whetstone parts is higher than the grinding ability of the divided whetstone part, and the second whetstone is formed in a columnar shape and has the same shape. It is preferable to have the grinding ability of:

One embodiment of the glass plate chamfering method of the present invention,
The grindstone is composed of at least a first grindstone and a second grindstone,
The first whetstone is formed in a columnar shape and is axially divided into at least two or more divided whetstone parts, and the grinding ability of one of the divided whetstone parts is the same as that of the other divided whetstone part. Higher than the grinding capacity,
The second grindstone is configured from the grindstone having a cylindrical shape and the same grinding ability,
After pressing one of the divided whetstone portions having a high grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A first chamfering step of grinding the one end face by rotating the first grindstone around its central axis,
After pressing the second whetstone against one end face of the glass plate, the second whetstone and the glass plate are relatively moved in one extending direction of the one end face, and the second whetstone is moved. A second chamfering step of grinding the one end face by rotating the grindstone about its central axis,
After pressing the second whetstone against one end surface of the glass plate, the second whetstone and the glass plate are relatively moved in the other extending direction of the one end surface, A third chamfering step of grinding the one end face by rotating the whetstone around its central axis;
After pressing the other split whetstone part having a low grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are moved in the other extending direction of the one end surface. A fourth chamfering step of relatively moving and grinding the one end face by rotating the first grindstone about its central axis;
It is preferable to provide

  In one aspect of the glass sheet chamfering apparatus of the present invention, it is preferable that the glass sheet has a rectangular shape, and the grindstone is arranged to face two opposite end faces of the glass sheet.

  In one aspect of the glass sheet chamfering method of the present invention, it is preferable that the glass sheet has a rectangular shape, and the grindstone is arranged to face two opposite end faces of the glass sheet.

  The chamfering apparatus and the chamfering method according to the present invention include a first grinding step in which a grindstone is relatively moved forward (1 Pass) with respect to one end surface of a glass plate in one extending direction to grind, In the second grinding step in which the grindstone is moved backward (2 Pass) relative to the end face in the extending direction in the other direction to grind, the same one end face is ground a plurality of times without increasing the number of grindstones. It is characterized by chamfering. Also, by repeating the forward movement twice (from 1 Pass to 2 Pass), the same one end surface can be chamfered without increasing the number of grindstones.

  According to the whetstone according to one aspect of the present invention, a whetstone formed in a cylindrical shape is axially divided into at least two or more divided whetstone parts, and the grinding power of one of the divided whetstone parts is increased by the other divided whetstone. Higher than the grinding capacity of the part. That is, a single grindstone has a plurality of performances, and a grindstone portion selected according to the performance is used for chamfering a glass plate. For example, when performing the first grinding process on the end face, one of the divided whetstone parts having a high grinding ability is pressed against the end face of the glass plate to perform the grinding. Next, in the case of performing the second chamfering, the other divided whetstone part having low grinding ability is pressed against the end face to perform the grinding.

  As described above, in the present invention, one grinding wheel has two or more types of grinding ability. Therefore, at least two wheels, a first whetstone and a second whetstone, are provided as whetstones, and the first whetstone and the second whetstone are each divided in the axial direction to provide a split whetstone portion. Perform rough grinding in the second split whetstone part, perform medium grinding in the second split whetstone part, perform finishing processing in the third split whetstone part, and apply it to the fourth split whetstone part. Mirroring can also be performed. In addition, one grinding wheel may have four types of grinding ability. The first whetstone is divided into four parts in the axial direction to provide four divided whetstone parts, and the first divided whetstone part performs rough grinding, and the second divided whetstone part performs medium grinding. Processing may be performed, finishing may be performed at the third divided grinding wheel portion, and mirror finishing may be performed at the fourth divided grinding wheel portion. In this case, the second grindstone is unnecessary. In other words, the technical idea of the present invention is to gradually remove chippings and cracks generated on the end face by the preceding processing in a plurality of subsequent processing steps, and to process the end face into a mirror surface in the final processing step. That is, a plurality of grinding wheels having different grinding capabilities are provided on one grinding wheel.

  Thereby, according to the whetstone for a glass plate of the present invention, the chamfering quality of the glass plate can be improved without increasing the number of whetstones.

  The “grinding ability” described in the specification and the claims means the first grinding step, the second grinding step, the first chamfering step, the second chamfering step, and the third chamfering step as described above. Means the grinding / polishing ability of the grindstone used in the step, the fourth chamfering step, and the like, that is, the performance of the grindstone. The grindstone can be broadly classified into a grindstone mainly for “grinding” and a grindstone mainly for “polishing” as described below.

As the grindstone mainly for “grinding”, a hard grindstone in which abrasive grains of diamond or CBN (Cubic Boron Nitride: cubic boron nitride) are fixed by a metal bond can be exemplified. An electrodeposited diamond grindstone can also be exemplified. By changing the grain size of the abrasive grains of these grindstones, a plurality of types of grinding processes such as a rough grinding process and a medium grinding process can be performed.
The grinding wheel which mainly "polishing", diamond, green silicon carbide (GC), alumina (Al 2 O _3), pumice, or butyl rubber grindstone such as garnet, and fixed with bonding, such as natural rubber, or resin A grindstone can be exemplified. By changing the grain size of the abrasive grains and the type of bond, a plurality of types of polishing processes such as finishing and mirror finishing can be performed.

  Furthermore, the “columnar shape” that is the shape of the grindstone includes a disk shape and a cylindrical shape. Further, a whetstone in which a ring-shaped groove is formed on the surface and a whetstone having a flat surface are also included in the “columnar shape”.

  In a conventional chamfering apparatus, one end surface of a glass plate is chamfered in the second direction by 1 Pass (forward movement). In one embodiment of the present invention, after 1 Pass is completed, the grindstone and the glass plate are moved to a third position. In the second direction, and 2 Pass (return) in the second direction. Thereby, the second chamfering process (that is, the second chamfering step) can be performed on the end surface of the glass plate.

  According to one aspect of the present invention, for example, in a form in which two grindstones are arranged on one end face, one grindstone of the first grindstone that first strikes one end face is used as a grindstone for rough grinding, and the other grindstone is used. Is a grindstone for mirror finishing. Then, one of the second grinding stones that comes into contact with one end surface next is a grinding stone for medium grinding, and the other grinding stone is a grinding stone for finishing.

  In this case, one pass of the first grindstone and one of the second grindstones are processed by 1 Pass, and thereafter, the other grindstone of the second grindstone and the other grindstone of the first grindstone are used. 2 Pass processing.

  Thus, in the present invention, the machining process configured by the rough grinding and the finishing in the conventional chamfering apparatus is changed to the rough grinding, the medium grinding, the finishing, and the mirror finishing without increasing the number of grinding wheels in the present invention. It can be configured in four steps of processing. For example, as described above, the above four steps can be performed using two grindstones. Therefore, in the present invention, the quality of chamfering can be significantly improved without increasing the number of grinding wheels.

  Further, in a form in which two grindstones are arranged on one end face, one grindstone of the first grindstone, which first contacts one end face, is a grindstone for rough grinding, and the other grindstone is a grindstone for mirror finishing. . Then, the grindstone of the second grindstone which comes into contact with one end face next is used as a grindstone for medium grinding.

  In this case, 1 Pass processing is performed with one of the first grindstones and the second grindstone, and thereafter, 2 Pass processing is performed with the second grindstone and the other grindstone of the first grindstone.

  Further, in a form in which two grindstones are arranged on one end face, the first grindstone that first hits one end face is a grindstone for rough grinding. Then, the second grindstone, which is next to one end face, is used as a grindstone for medium grinding.

  In this case, 1 Pass processing is performed with the first grinding stone and the second grinding stone, and then 2 Pass processing is performed with the second grinding stone.

  In one aspect of the present invention, it is preferable that the glass plate has a rectangular shape, and the grindstone is arranged to face two opposite end surfaces of the glass plate.

  According to one embodiment of the present invention, by turning the glass plate 90 degrees with respect to the grindstone, the four end surfaces of the rectangular glass plate can be chamfered efficiently.

  According to the glass sheet chamfering apparatus, the glass sheet chamfering method, and the glass sheet manufacturing method according to the present invention, the glass sheet chamfering quality can be improved without increasing the number of grindstones.

The top view showing the schematic structure of the glass sheet chamfering device of the embodiment to which the whetstone for the glass plate of the embodiment is applied. Principal part enlarged perspective view showing the vertical position of the grindstone during forward movement of the glass plate in the direction of arrow A. Principal part enlarged perspective view showing the vertical position of the grindstone during the backward movement of the glass plate in the direction of arrow B. FIGS. 4 (A), 4 (B), 4 (C), 4 (D), and 4 (E) show a state in which the end surface of the glass plate is sequentially chamfered by each grindstone. Illustration shown in 5 (A), 5 (B), 5 (C), 5 (D), and 5 (E) are explanatory diagrams showing the chamfering method by the chamfering device of the embodiment over time. 6 (A), 6 (B), 6 (C), 6 (D), 6 (E), and 6 (F) show another chamfering method by the chamfering apparatus of the embodiment. Explanatory diagram 7 (A), 7 (B), 7 (C), 7 (D), and 7 (E) are explanatory views showing another chamfering method of the embodiment over time. 8 (A), 8 (B), 8 (C), 8 (D), and 8 (E) are explanatory views showing another chamfering method of the embodiment over time.

  Hereinafter, preferred embodiments of a glass sheet chamfering apparatus, a glass sheet chamfering method, and a glass sheet manufacturing method according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 illustrates a first grindstone 10 (hereinafter, the first grindstone 10 is also simply referred to as a grindstone 10) and a second grindstone 12 (hereinafter, the second grindstone 12 is simply referred to as a grindstone 12) according to the embodiment of the present invention. FIG. 1 is a plan view illustrating a schematic configuration of a glass sheet chamfering apparatus 14 according to an embodiment, each of which includes a pair. The chamfering device 14 is a device used in the chamfering step in the method for manufacturing a glass sheet of the embodiment including a melting step, a forming step, a cutting step, and a chamfering step.

  Further, as the chamfering device 14, a device for chamfering the four end surfaces 16A to 16D of the glass plate 16 for a liquid crystal display having a thickness of 0.7 mm or less with the grindstones 10 and 12 is exemplified. The grindstones 10 and 12 will be described later.

  In addition, the glass plate applicable to the chamfering device 14 is not limited to the glass plate 16 for a liquid crystal display. For example, another FPD glass plate such as a glass plate for a plasma display or a glass plate for an LED display may be used, or a general glass plate for a solar cell, for lighting, for a building material, for a mirror, or the like. Further, the thickness of the glass plate is not limited to 0.7 mm or less, and may be more than 0.7 mm. Further, the end surface is chamfered by the chamfering device 14 even if it is not limited to a glass plate and is a metal or resin plate.

[Overall configuration of chamfering device 14]
The chamfering device 14 moves the platen 18 that holds the rectangular glass plate 16 by suction and the platen 18 in the horizontal direction (second direction) in the direction of arrow A (that is, 1 Pass) and in the direction of arrow B. A moving device (that is, a second moving means) 20 that moves (2 Pass) and grinds the same end surfaces 16A and 16B a plurality of times is provided. In addition, the chamfering device 14 of the embodiment is a device that reciprocates the glass plate 16 with respect to the grindstones 10 and 12 that are fixedly arranged. What is necessary is just a device which reciprocates relatively in the horizontal direction along the extending direction of 16A, 16B.

  Further, the chamfering device 14 is a columnar grindstone 10, 12 that is pressed against the end faces 16A to 16D of the glass plate 16 to process the chamfered face into the end faces 16A to 16D, and a motor (rotational) that rotates the grindstones 10, 12 at high speed. (Means) 22, 24. Although two whetstones 10 and 12 are arranged with respect to opposed end surfaces 16A and 16B of the glass plate 16, three or more whetstones may be arranged.

  Further, the chamfering device 14 is configured to move the grindstones 10 and 12 up and down in the vertical direction (third direction) together with the motors 22 and 24 (that is, the third moving means) 26 and 28, and the grinding by the grindstones 10 and 12. Nozzles 30 and 32 for injecting the cooling liquid into the section, a control device (control means) 34 and the like are provided. In addition, feeders (that is, first moving means) 31, 33 for pressing the grinding wheels 10, 12 in a horizontal direction against the end face 16A of the glass plate 16 and moving the grindstones 10 and 12 in a horizontal retreat direction with respect to the end face 16A (see FIG. 2). The chamfering device 14 according to the embodiment is a device for moving the grindstones 10 and 12 up and down with respect to the glass plate 16, and the grindstones 10 and 12 and the glass plate 16 are combined with the main surface 16 </ b> E of the glass plate 16 (FIG. And a device that relatively moves up and down along a vertical direction perpendicular to the horizontal direction. Further, the apparatus is not limited to a device for moving the grindstones 10 and 12 forward and backward with respect to the end surface 16A by the feeders 31 and 33, but may be any device for relatively moving the grindstones 10 and 12 between the end surface 16A of the glass plate 16 and the grindstones 10 and 12. Good. The grinding allowance is set according to the feed amount of the feed devices 31, 33. Further, the feed amount is controlled by the control device 34 based on the grinding ability and performance of the grindstones 10 and 12.

  The control device 34 controls each operation of the moving device 20, the number of rotations / rotational directions of the motors 22 and 24, the lifting devices 26 and 28, and the feeding devices 31 and 33. A control method of each operation by the control device 34 will be described later.

  FIG. 2 is an enlarged perspective view of a main part showing the vertical positions of the grindstones 10 and 12 during forward movement of the glass plate 16 in the direction of arrow A.

  FIG. 3 is an enlarged perspective view of the main part showing the vertical positions of the grindstones 10 and 12 during the backward movement of the glass plate 16 in the direction of arrow B.

  As shown in FIGS. 2 and 3, the grindstone 10 is driven to rotate by a motor 22 about a central axis 10A. Further, by controlling the motor 22 by the control device 34 (see FIG. 1), the rotation speed is controlled, and the forward and reverse rotation directions indicated by the arrow C in FIG. 2 and the arrow D in FIG. 3 are controlled. . In the embodiment, when the glass plate 16 is moved in the direction of arrow A, the grindstone 10 is rotated in the direction of arrow C opposite to the direction of movement. Similarly, when the glass plate 16 is moved backward in the direction of the arrow B, the rotation direction is changed to the direction of the arrow D opposite to the direction of the movement. Note that conversion of the rotation direction of the grindstone 10 is not essential. By not changing the rotation direction of the grindstone, the processing time can be reduced.

  Similarly, the grindstone 12 is driven to rotate by the motor 24 about the central axis 12A. Further, by controlling the motor 24 by the control device 34 (see FIG. 1), the rotation speed is controlled, and the forward and reverse rotation directions indicated by the arrow C in FIG. 2 and the arrow D in FIG. 3 are controlled. . In the embodiment, when the glass plate 16 is moved in the direction of arrow A, the grindstone 12 is rotated in the direction of arrow C facing the direction of movement. Similarly, when the glass plate 16 is moved backward in the direction of the arrow B, the rotation direction is changed to the direction of the arrow D opposite to the direction of the movement. It is not essential to change the rotation direction of the grindstone 12.

<Configuration of First Grinding Stone 10 and Second Grinding Stone 12>
The grindstone 10 is divided into two grindstone portions in the axial direction, and the grinding ability of one divided grindstone portion (the upper divided grindstone portion 36 in the illustrated example) is different from that of the other divided grindstone portion (the upper illustrated portion in the illustrated example). Is set higher than the grinding ability of the divided whetstone part 42).

  Similarly, the grindstone 12 is also axially divided into two divided grindstone portions, and the grinding ability of one divided grindstone portion (upper divided grindstone portion 38) is the same as that of the other divided grindstone portion (lower divided grindstone portion 40). It is set higher than the grinding ability.

  The number of divisions of the grindstones 10 and 12 is not limited to two, and may be divided into three or more.

  The divided grindstone portions 36, 38, 40, and 42 of the embodiment roughen the end faces 16A and 16B by the reciprocating movement of the glass plate 16 described above (that is, a first chamfering step: a first grinding step). Medium grinding (that is, second chamfering step: first grinding step), finishing (that is, third chamfering step: second grinding step), and mirror finishing (that is, fourth chamfering step: first grinding step) (Grinding process 2), that is, the respective grinding capabilities, that is, the performances, are set so that they can be sequentially performed.

  Specifically, the split whetstone part 36 can perform rough grinding, the split whetstone part 38 can perform medium grinding, the split whetstone part 40 can perform finishing processing, and the split whetstone part 42 can perform mirror finishing. Performance is set as follows.

  FIGS. 4 (A) to 4 (E) are explanatory diagrams showing a state in which the same end surface 16A of the glass plate 16 is sequentially chamfered by the divided grindstone portions 36, 38, 40, 42. is there.

  FIG. 4A shows the shape of the end face 16A of the glass plate 16 before chamfering. That is, the end surface 16A of the glass plate 16 is a cut surface cut in a cutting process prior to the chamfering process, and is formed in a direction orthogonal to the main surface 16E.

  FIG. 4B shows the shape of the end face 16A on which the rough grinding has been performed by the divided grindstone portion 36, and an annular groove 36A having a U-shaped cross section, which is a grinding groove of the divided grindstone portion 36 (FIG. 2, FIG. (See FIG. 3). The roughness of the end face 16A after the rough grinding is rough, and chipping and cracks caused by the rough grinding frequently occur on the surface.

  The cross-sectional shape of the annular groove 36A of the divided grindstone portion 36 shown in FIGS. 2 and 3 is not limited to the U-shape, and may be a V-shape or a concave shape. Although the number of the annular grooves 36A may be one, it is preferable that a plurality of the annular grooves 36A be provided at predetermined intervals in the axial direction of the divided grindstone portions 36 in order to save the replacement work of the divided grindstone portions 36. Since a plurality of annular grooves 36A are provided in the divided grindstone portion 36, when the used annular groove 36A reaches the end of its life, the lifting / lowering device 26 moves the divided grindstone portion 36 vertically in the pitch unit of the annular groove 36A. By doing so, the end face 16A can be roughly ground using the new annular groove 36A without replacing the divided whetstone portion 36.

  FIG. 4C shows the shape of the end face 16 </ b> A that has been subjected to the medium grinding by the divided whetstone portion 38. By pressing the surface of the divided whetstone portion 38 against the end face 16A, chipping and cracks, which have frequently occurred in the rough grinding, are almost removed by polishing.

  FIG. 4D shows the shape of the end face 16 </ b> A on which the finishing processing has been performed by the divided whetstone part 40. By pressing the surface of the split whetstone portion 40 against the end face 16A, chipping and cracks that have frequently occurred in the rough grinding are further polished and removed.

  FIG. 4E shows the shape of the end face 16 </ b> A on which the finishing processing has been performed by the divided whetstone part 42. By pressing the surface of the divided whetstone portion 42 against the end face 16A, chipping and cracks that have frequently occurred in the rough grinding are almost completely polished and removed, and the end face 16A is mirror-finished. That is, the end surface 16A is processed into a mirror surface that is assumed not to generate dust from the end surface 16A.

  Here, examples of the divided grindstone portions 36 and 38 that mainly perform “grinding” include hard grindstones in which abrasive grains of diamond or CBN are fixed by metal bonds. An electrodeposited diamond grindstone can also be exemplified. By setting the grain size of the abrasive grains of the divided grindstone portion 36 to, for example, 270 to 600, rough grinding can be performed by the divided grindstone portion 36. More preferably, the grain size of the abrasive grains of the divided whetstone portion 36 is 325 to 500. By setting the grain size of the abrasive grains of the divided grindstone portion 38 to, for example, 400 to 1000, medium grinding can be performed by the divided grindstone portion 38. More preferably, the grain size of the abrasive grains of the divided whetstone portion 38 is 420 to 600.

As the divided grindstone portions 40 and 42 that mainly perform “polishing”, grindstones such as diamond, CBN, green silicon carbide (GC), alumina (Al ₂ O ₃ ), pumice, or garnet are used as butyl rubber, natural rubber, Or, a grindstone fixed by a bond such as a resin can be exemplified. Further, by setting the grain size of the abrasive grains of the divided whetstone part 40 to, for example, 270 to 800, and the grain size of the abrasive grains of the divided whetstone part 42 to, for example, 600 to 4000, the finishing process is performed by the divided whetstone part 40. Mirror processing can be performed by the divided whetstone part 42.
The divided whetstone portion 38 is a whetstone in which a whetstone such as diamond, CBN, green silicon carbide (GC), alumina (Al ₂ O ₃ ), pumice, or garnet is fixed with a bond such as butyl rubber, natural rubber, or resin. In this case, by setting the grain size of the abrasive grains of the divided whetstone portion 38 to, for example, 400 to 600, medium grinding can be performed.

[Operation of chamfering device 14]
First, a grinding allowance by the grindstones 10 and 12 is set in the control device 34 of FIG. At this time, the control device 34 for controlling the moving device 20 such that the processing time at 1 Pass and 2 Pass (reciprocation) of the embodiment is substantially equal to the conventional 1 Pass processing time based on the conventional processing time at 1 Pass. Is preferably set. In this way, the chamfering quality of the glass plate 16 can be improved in the same time as the conventional processing at 1 Pass. In this case, it is preferable that the grain size of the abrasive grains of the divided grindstone portion 36 be 200 to 450, and the grain size of the abrasive grains of the divided grindstone portion 38 be 350 to 500. Further, in the case of performing the processing in which the processing time is short, it is preferable that the 2Pass processing time in the backward movement is shorter than the 1Pass processing time in the forward movement. Further, when performing finishing-oriented processing, it is preferable to make the backward 2 Pass processing time longer than the forward 1 Pass processing time. In addition, the 1 Pass processing time of the forward movement and the 2 Pass processing time of the backward movement may be set to the same time.

  Next, at the time of forward movement of the glass plate 16 by the surface plate 18, the end faces 16A and 16B pass through the divided grindstone portions 36 and 38, and at the time of backward movement, the end faces 16A and 16B pass through the divided grindstone portions 40 and 42. An operation program of the control device 34 for controlling the lifting devices 26 and 28 is set.

  Next, the motors 22 and 24 are controlled so that the grindstones 10 and 12 rotate in the direction of arrow C when the glass plate 16 is moved forward by the platen 18, and the grindstones 10 and 12 rotate in the direction of arrow D when moving backward. The operation program of the control device 34 to be executed is set. As described above, the rotation direction of the grindstones 10 and 12 may be constant without being changed.

  Thus, the pre-setting operation by the chamfering device 14 is completed.

  Next, the glass plate 16 cut in the cutting step is suction-held on the suction surface on the upper surface of the surface plate 18. Thereafter, the control device 34 controls each member of the chamfering device 14 to start chamfering the end surfaces 16A and 16B of the glass plate 16.

  That is, the control device 34 controls the moving device 20 to move the glass sheet 16 forward in the direction of arrow A in FIG. Then, the control device 34 controls the motors 22 and 24 to rotate the grindstones 10 and 12 in the direction of arrow C in FIG. The control device 34 controls the lifting devices 26 and 28 to adjust the height of the grindstones 10 and 12 to the height at which the end face 16A passes through the divided grindstone portions 36 and 38.

  5 (A) to 5 (E) are explanatory diagrams showing the chamfering method by the chamfering device 14 over time.

  FIG. 5A shows a state in which the height of the grindstones 10 and 12 is adjusted to the height at which the end face 16A passes through the divided grindstone portions 36 and 38, and the glass plate 16 is moved in the direction of arrow A. It is a schematic side view.

  Thereafter, the end face 16A of the glass plate 16 is first roughly ground by the divided grindstone portion 36 by a continuous forward movement of the glass plate 16 as shown in FIG. Medium grinding is performed by the grindstone portion 38. That is, a second chamfering step is performed.

  At the time of rough grinding and medium grinding, a coolant is injected from the nozzles 30 and 32 in FIG. 1 to the processing portion where the grinding wheels 10 and 12 and the end face 16A are in contact. Thereby, since the processed portion is cooled by the cooling liquid, it is possible to reduce the occurrence of burning, chipping, and the like generated on the end face 16A of the glass plate 16. In addition, chipping that occurs at the boundaries between the two main surfaces of the glass plate 16 and the end surfaces 16A and 16B can be reduced. In addition, as a cooling liquid, pure water can be illustrated.

  As shown in FIG. 5C, when the middle grinding process of the end face 16A is completed and the glass plate 16 is located at the end point of the forward movement, the control device 34 of FIG. Stop the movement temporarily.

  Thereafter, as shown in FIG. 5C, the control device 34 controls the moving device 20 to move the glass plate 16 in the direction of arrow B by the platen 18. Then, the control device 34 controls the motors 22 and 24 to rotate the grindstones 10 and 12 in the direction of arrow D in FIG. Then, the control device 34 in FIG. 1 controls the lifting devices 26 and 28 to adjust the heights of the grindstones 10 and 12 to the height at which the end face 16A passes through the divided grindstone portions 40 and 42. That is, the grindstones 10 and 12 are moved upward in the direction of arrow E in FIG.

  FIG. 5D is a schematic side view showing the state at the start of the return movement.

  As shown in FIG. 5 (E), the returning glass plate 16 is finished by passing the end face 16A through the divided grindstone portion 40 (that is, subjected to the third chamfering step) and passed through the divided grindstone portion 42. Then, mirror finishing is performed (that is, a fourth chamfering step is performed).

  The other opposing end surfaces 16C and 16D of the glass plate 16 may be chamfered by the grindstones 10 and 12 having the same performance and arranged at the subsequent stage of the grindstones 10 and 12 in FIG. That is, in a device having the same mechanism as that shown in FIG. 1 and disposed at the subsequent stage of FIG. 1, the glass plate 16 is disposed by rotating the glass plate 16 by 90 degrees around a perpendicular to the main surface, and a grindstone having the same performance as the grindstones 10 and 12 is used. The end faces 16C and 16D may be chamfered.

  Alternatively, after the glass plate 16 is moved in the direction B by the surface plate 18 and returned to the original position, the glass plate 16 is rotated 90 degrees by the surface plate 18 around an axis perpendicular to the main surface direction of the glass plate 16. After that, while the glass plate 16 is moved in the direction A by the surface plate 18, the pair of grindstones 10 and 12 whose intervals are changed according to the length in the extending direction of the end surfaces 16 </ b> A and 16 </ b> B of the glass plate 16 are respectively used. The end faces 16C and 16D may be chamfered.

[Characteristics of the first whetstone 10 and the second whetstone 12]
The grindstone 10 (including the grindstone 12) of the embodiment is divided into at least two or more divided grindstone portions in the axial direction, and the grinding capability of the divided grindstone portion 36 is higher than the grinding capability of the divided grindstone portion 42. . That is, a single grindstone 10 is provided with a plurality of performances, and a grindstone selected according to the performance is used for chamfering the glass plate 16.

  For example, when performing the first chamfering process on the end face 16A, the divided grindstone portion 36 having a high grinding ability is pressed against the end face 16A of the glass plate 16 for processing. Next, in the case of performing the second chamfering process, the divided grindstone portion 42 having a low grinding ability is pressed against the end face 16A to perform the processing.

  As described above, the present invention is characterized in that one grindstone 10 has two or more types of performance. Therefore, at least two wheels, a first whetstone and a second whetstone, are provided as whetstones, and the first whetstone and the second whetstone are each divided in the axial direction to provide a split whetstone portion. Perform rough grinding in the second split whetstone part, perform medium grinding in the second split whetstone part, perform finishing processing in the third split whetstone part, and apply it to the fourth split whetstone part. Mirroring can also be performed. In addition, one grinding wheel may have four types of grinding ability. The first whetstone is divided into four parts in the axial direction to provide four divided whetstone parts. The first divided whetstone part is used for rough grinding, and the second whetstone part is used for medium grinding. Processing may be performed, finishing may be performed at the third divided grinding wheel portion, and mirror finishing may be performed at the fourth divided grinding wheel portion. In this case, the second grindstone is unnecessary.

  Thereby, according to the whetstone for a glass plate of the present invention, the chamfering quality of the glass plate can be improved without increasing the number of whetstones.

[Features of chamfering device 14]
While moving the glass plate 16 in the direction of arrow A by the moving device 20, the divided grindstone portion 36 is rotated by the motor 22, and the divided grindstone portion 36 is pressed against the end surface 16 </ b> A of the glass plate 16. Thereby, the first chamfering process can be performed on the end face 16A (that is, the first chamfering step). Next, the whetstone 10 is moved in the direction of arrow E (see FIG. 5C) by the elevating device 26, and the glass plate 16 is moved back in the direction of arrow B by the moving device 20, and the divided whetstone portion 42 is moved to the end face 16A. Press against. Thereby, the second chamfering process can be performed on the end face 16A (that is, the second chamfering step).

  Here, the conventional chamfering device and the chamfering device 14 of the embodiment will be compared.

  The conventional chamfering device is a device for chamfering the end face 16A by moving the glass plate 16 by 1 Pass (forward movement) in the direction of arrow A with respect to the grindstone.

  On the other hand, the chamfering device 14 of the embodiment changes the height of the grindstone 10 after the completion of 1 Pass, moves the glass plate 16 by 2 Pass (that is, moves backward) in the direction of arrow B, and sets the end face 16A of the glass plate 16 to the end surface 16A. Is a device for performing a second chamfering process. Therefore, the chamfering method using the conventional chamfering device and the chamfering method using the chamfering device 14 of the embodiment are completely different.

[Other Embodiments of Chamfering Method]
6 (A) to 6 (F) are explanatory diagrams showing another chamfering method by the chamfering device 14 over time.

  As shown in FIGS. 6A to 6F, the grindstone 10 is provided with a divided grindstone portion 36 and a divided grindstone portion 40, and the grindstone 12 is provided with a divided grindstone portion 38 and a divided grindstone portion 42. Have been.

  FIG. 6A shows a state in which the height of the grindstones 10 and 12 is adjusted to the height at which the end face 16A passes through the divided grindstone portions 36 and 38, and the glass plate 16 is moved in the direction of arrow A. It is a schematic side view.

  Thereafter, as a first chamfering step, the end face 16A of the glass plate 16 is first subjected to rough grinding by the divided whetstone portion 36 by the forward movement of the glass plate 16 as shown in FIG. As the second chamfering step, the middle grinding is performed by the divided whetstone portion 38.

  As shown in FIG. 6C, when the middle grinding process of the end face 16A is completed and the glass plate 16 is located at the end point of the forward movement, the control device 34 of FIG. Stop the movement temporarily.

  Thereafter, the control device 34 controls the feeding devices 31 and 33 to retract the grindstones 10 and 12 from the abutting position of the end face 16A, and controls the elevating devices 26 and 28 so that the end face 16A is , 42 are adjusted to the height at which they pass. That is, the grindstones 10 and 12 are moved upward in the direction of arrow E in FIG. Then, the control device 34 controls the moving device 20 to move the glass plate 16 backward in the direction of arrow B by the surface plate 18, as shown in FIG. 6E, at the end position of the backward movement of the glass plate 16. Let it. Thereafter, the controller 34 controls the feeders 31 and 33 to move the grinding wheels 10 and 12 to the abutting position of the end face 16A. The abutting position is defined as a grinding wheel diameter, an additional driving amount according to a preceding grinding amount, and a grinding wheel according to a bond type with respect to each of the divided grinding wheels 36, 38, 40, and 42 of the grinding wheels 10 and 12. Is set based on the degree of wear of the glass plate and the additional drive-in amount for each processing of one glass sheet according to the degree of wear. Then, the control device 34 controls the moving device 20 to move the glass plate 16 forward again in the direction of arrow A by the surface plate 18.

  As shown in FIG. 6 (F), the forward moving glass plate 16 is finished by passing the end face 16A through the divided grindstone portion 40 (that is, subjected to the third chamfering step) and passed through the divided grindstone portion 42. Then, mirror finishing is performed (that is, a fourth chamfering step is performed).

  FIGS. 7A to 7E are explanatory diagrams showing another chamfering method over time.

  As shown in FIGS. 7A to 7E, the grindstone 10 is provided with a divided grindstone portion 36 and a divided grindstone portion 42, and the grindstone 12 is provided with only the same divided grindstone portion 40. .

  FIG. 7A shows a state in which the height of the grindstones 10 and 12 is adjusted to the height at which the end face 16A passes through the divided grindstone portions 36 and 40, and the glass plate 16 is moved in the direction of arrow A. It is a schematic side view.

  Thereafter, the end face 16A of the glass plate 16 is first roughly ground by the divided grindstone portion 36 due to the continuous forward movement of the glass plate 16 as shown in FIG. 7B (that is, the first chamfering step is performed). Then, finish processing is performed by the divided grindstone portion 40 (that is, a second chamfering step is performed). In this case, the grinding force of the divided whetstone portion 40 is weak.

  As shown in FIG. 7C, when the finish processing of the end face 16A is completed and the glass plate 16 is located at the end point of the forward movement, the control device 34 of FIG. Is temporarily stopped.

  Thereafter, the control device 34 controls the lifting devices 26 and 28 to adjust the heights of the grindstones 10 and 12 to the height at which the end face 16A passes through the divided grindstone portions 40 and 42. That is, the grindstones 10 and 12 are moved upward in the direction of the arrow E in FIG. Then, the control device 34 controls the moving device 20 to move the glass plate 16 backward in the direction of arrow B by the surface plate 18 as shown in FIG.

  As shown in FIG. 7 (E), the glass plate 16 to be returned is subjected to the second finishing process (that is, the third chamfering step) by passing the end face 16A through the divided grindstone portion 40, and the divided grindstone portion 42 is formed. Is mirror-finished (ie, a fourth chamfering step is performed).

  In this other chamfering method, the grinding force of the divided grindstone portion 40 during the forward movement is weak, but the grinding is also performed by the divided grindstone portion 40 during the backward movement, so that the chamfering with the required roughness as a whole can be performed. .

  8 (A) to 8 (E) are explanatory diagrams showing another chamfering method over time.

  As shown in FIGS. 8A to 8E, the grindstone 10 is provided with only the same divided grindstone portion 36, and the grindstone 12 is provided with the divided grindstone portion 38 and the divided grindstone portion 40.

  FIG. 8A shows a state in which the height of the grindstones 10 and 12 is adjusted to a height at which the end face 16A passes through the divided grindstone portions 36 and 38, and the glass plate 16 is moved in the direction of arrow A. It is a schematic side view.

  Thereafter, the end face 16A of the glass plate 16 is first subjected to rough grinding by the divided grindstone portion 36 due to the continuous forward movement of the glass plate 16 as shown in FIG. 8B (that is, the first chamfering step is performed). ) Then, medium grinding is performed by the divided whetstone portion 38 (that is, a second chamfering step is performed).

  As shown in FIG. 8C, when the middle grinding process of the end face 16A is completed and the glass plate 16 is located at the end point of the forward movement, the control device 34 of FIG. Stop the movement temporarily.

  Thereafter, the control device 34 controls the feed device 31 to retreat the grindstone 10 from the contact position of the end face 16A, and controls the elevating device 28 to a height at which the end face 16A passes through the divided grindstone portion 40. Adjust the height of the grindstone 12. That is, the grindstone 12 is moved upward in the direction of the arrow E in FIG. Then, the control device 34 controls the moving device 20 to move the glass plate 16 backward in the direction of arrow B by the surface plate 18 as shown in FIG.

  As shown in FIG. 8E, the returning glass plate 16 is finished by passing the end face 16A through the divided grindstone portion 40 as a third chamfering step.

  In this other chamfering method, the mirror surface processing by the divided whetstone part 42 is not performed. However, if the finishing processing equivalent to the mirror surface processing can be performed by increasing the grain size of the divided whetstone part 40, the divided whetstone part 42 It is not necessary to provide.

[Characteristics of glass sheet manufacturing method using chamfering device 14]
The method for manufacturing a glass plate according to the embodiment of the present invention includes:
A melting step of heating the glass raw material to obtain a molten glass,
A molding step of obtaining a glass ribbon by making the molten glass into a plate shape,
A cutting step of cutting the glass ribbon to obtain a glass plate,
A chamfering step of chamfering the glass plate by the method for chamfering the glass plate,
Having.
In the melting step, silica sand and other glass raw materials are adjusted so as to have a desired glass composition, and the raw materials are put into a melting furnace, and are preferably heated to about 1400 ° C. to 1650 ° C. to obtain a molten glass.
In the forming step, a molten glass is formed into a plate shape by applying a float method, a fusion method or the like to obtain a glass ribbon. For example, in the float method, a molten glass is flowed on a molten metal to form a plate to obtain a glass ribbon.
In the cutting step, the glass ribbon is gradually cooled, and then the glass ribbon is cut into a predetermined size to obtain a glass plate.
In the chamfering method, the glass plate is chamfered by the above-described glass plate chamfering method.
According to the method for manufacturing a glass sheet of the present invention, it is possible to manufacture a glass sheet 16 with improved chamfering quality.

  In addition, it is possible to cope with only the operation software modification of the control device 34 without performing a major modification such as adding a grindstone rotating device, and the time and cost required for the modification can be greatly reduced.

  Furthermore, by increasing the processing speed of the grindstones 10 and 12, the processing quality of the chamfer can be improved without changing the processing tact, that is, without lowering the productivity of the glass plate 16.

  Furthermore, as another chamfering method, the chamfering method of the present invention can be applied to the chamfering method disclosed in JP-A-2008-49449. That is, the first chamfering grindstone performs chamfering from one center of one side to the other end of one side in one side of the glass plate, and the second chamfering grindstone performs the same side from one end of the same side. The chamfering apparatus and the chamfering method of the present invention can be applied to the chamfering method disclosed in the above-mentioned gazette, wherein the chamfering is performed to a substantially central portion.

According to the glass sheet chamfering apparatus, the glass sheet chamfering method, and the glass sheet manufacturing method according to the present invention, the glass sheet chamfering quality can be improved without increasing the number of grindstones.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2014-257462 filed on December 19, 2014 are incorporated herein by reference. .

  10, 12: grinding wheel, 14: chamfering device, 16: glass plate, 16A to 16D: end face, 18: surface plate, 20: moving device, 22, 24: motor, 26, 28: elevating device, 30, 32: nozzle , 31, 33 ... feeding device, 34 ... control device, 36, 38, 40, 42 ... divided whetstone part.

Claims (7)

With a whetstone,
Rotating means for rotating the whetstone about its central axis,
A first moving unit that relatively moves the whetstone and the glass plate along a first direction orthogonal to an end surface of the glass plate,
A second moving unit that relatively reciprocates the grindstone and the glass plate along a second direction in which the end surface of the glass plate extends, and grinds the same end surface of the glass plate a plurality of times,
Third moving means for relatively moving the grinding stone and the glass plate along a main surface of the glass plate and a third direction orthogonal to the second direction;
Control means for controlling the first moving means, the second moving means, and the third moving means;
Equipped with a,
The whetstone includes at least a first whetstone and a second whetstone,
The first grindstone and the second grindstone are formed in a columnar shape and are axially divided into at least two or more divided grindstone portions, and the grinding ability of one of the divided grindstone portions is divided. A glass plate chamfering device that is higher than the grinding ability of the other split whetstone part. With a whetstone,
Rotating means for rotating the whetstone about its central axis,
A first moving unit that relatively moves the whetstone and the glass plate along a first direction orthogonal to an end surface of the glass plate,
A second moving unit that relatively reciprocates the grindstone and the glass plate along a second direction in which the end surface of the glass plate extends, and grinds the same end surface of the glass plate a plurality of times,
Third moving means for relatively moving the grinding stone and the glass plate along a main surface of the glass plate and a third direction orthogonal to the second direction;
Control means for controlling the first moving means, the second moving means, and the third moving means;
Equipped with a,
The whetstone includes at least a first whetstone and a second whetstone,
The first whetstone is formed in a columnar shape and is axially divided into at least two or more divided whetstone parts, and the grinding ability of one of the divided whetstone parts is the same as that of the other divided whetstone part. Higher than the grinding ability,
A chamfering apparatus for a glass plate, wherein the second grindstone has a cylindrical shape and the same grinding ability. The glass plate has a rectangular shape, chamfering apparatus for a glass plate according to claim 1 or 2, wherein the grinding wheel facing the second end surface facing the glass plate is placed. The grindstone is composed of at least a first grindstone and a second grindstone,
The first grindstone and the second grindstone are formed in a columnar shape and are axially divided into at least two or more divided grindstone portions, and the grinding ability of one of the divided grindstone portions is divided. It is higher than the grinding capacity of the other split whetstone part,
After pressing one of the divided whetstone portions having a high grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A first chamfering step of grinding the one end face by rotating the first grindstone around its central axis,
After pressing one of the divided whetstone portions having a high grinding ability of the second whetstone against one end surface of the glass plate, the second whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A second chamfering step of grinding the one end face by rotating the second grindstone about its central axis,
After pressing the other divided whetstone part having a low grinding ability of the second whetstone against one end surface of the glass plate, the second whetstone and the glass plate are moved in the other extending direction of the one end surface. A third chamfering step of relatively moving and grinding the one end face by rotating the second grindstone about its central axis;
After pressing the other split whetstone part having a low grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are moved in the other extending direction of the one end surface. A fourth chamfering step of relatively moving and grinding the one end face by rotating the first grindstone about its central axis;
A method for chamfering a glass sheet, comprising: The grindstone is composed of at least a first grindstone and a second grindstone,
The first whetstone is formed in a columnar shape and is axially divided into at least two or more divided whetstone parts, and the grinding ability of one of the divided whetstone parts is the same as that of the other divided whetstone part. Higher than the grinding capacity,
The second grindstone is configured from the grindstone having a cylindrical shape and the same grinding ability,
After pressing one of the divided whetstone portions having a high grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are relatively moved in one extending direction of the one end surface. A first chamfering step of grinding the one end face by rotating the first grindstone around its central axis,
After pressing the second whetstone against one end face of the glass plate, the second whetstone and the glass plate are relatively moved in one extending direction of the one end face, and the second whetstone is moved. A second chamfering step of grinding the one end face by rotating the grindstone about its central axis,
After pressing the second whetstone against one end face of the glass plate, the second whetstone and the glass plate are relatively moved in the other extending direction of the one end face, and the second whetstone is moved. A third chamfering step of grinding the one end face by rotating the whetstone around its central axis;
After pressing the other split whetstone part having a low grinding ability of the first whetstone against one end surface of the glass plate, the first whetstone and the glass plate are moved in the other extending direction of the one end surface. A fourth chamfering step of relatively moving and grinding the one end face by rotating the first grindstone about its central axis;
A method for chamfering a glass sheet, comprising: The glass plate chamfering method according to claim 4 , wherein the glass plate has a rectangular shape, and the grindstone is arranged to face two opposite end surfaces of the glass plate. A melting step of heating the glass raw material to obtain a molten glass,
Forming the molten glass into a plate to obtain a glass ribbon,
A cutting step of cutting the glass ribbon to obtain a glass plate,
A chamfering step of chamfering the glass sheet according to the glass sheet chamfering method according to any one of claims 4 to 6 ,
A method for producing a glass sheet, comprising:

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