Plate glass manufacturing method, manufacturing apparatus thereof, and plate glass

Abstract

This plate glass G production method relates to a plate glass G having a first region G1 and a second region G2 laid next to one another in the width direction and a scribe line S formed in the boundary portion of the regions G1, G2, on the side of front surfaces Ga, Gx, the method comprising a snapping step in which, in a state where the first region G1 is in contact with and supported by a back surface supporting member 3 from a back surface Gb side while the plate glass G is in a vertical attitude, a force oriented toward a back surface Gy is applied to the second region G2, thereby splitting the plate glass G along the scribe line S and cutting off the second region G2. In the snapping step, the first region G1 and the back surface supporting member 3 are brought into contact with one another so as to form a warping portion Gws following an up-down direction protruding on the front surface Ga, Gx side in the scribe line S formation region Gs.

Description

[Technical Field]

[0001] The present invention relates to improvements in glass sheet manufacturing techniques, including techniques for breaking glass sheets along scribe lines. [Background technology]

[0002] As is well known, glass sheets are used in a variety of fields, including glass substrates for displays such as liquid crystal displays, plasma displays, and organic electroluminescence (EL) displays, and cover glass for organic electroluminescence (EL) lighting. The production of this type of glass sheet involves processes such as sequentially cutting glass sheets of predetermined lengths from a glass ribbon and removing unnecessary regions along the edges of the glass sheet. In these processes, scribe lines are formed in the glass ribbon or glass sheet, and then the glass sheet or sheet is bent and split along the scribe lines to obtain the desired glass sheet.

[0003] A specific example of a method for obtaining a glass sheet by breaking is the method disclosed in Patent Document 1. In the method disclosed in this document, a scribe line is formed on the front side of the boundary between a first region and a second region arranged adjacent to each other in the width direction of the glass sheet, and while the first region is supported in contact with the back side by a back support member, the second region is pressed toward the back side by a rolling element. In this way, the glass sheet is broken along the scribe line to cut out the second region. The breaking is performed while the glass sheet is supported in a vertical position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-226549 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Document 1, when a glass sheet is supported in a vertical position, warping in the vertical direction may occur. This warping becomes more pronounced as glass sheets (such as glass sheets used in displays) have become thinner in recent years. The method disclosed in Patent Document 1 causes the following problems when breaking this type of glass sheet.

[0006] That is, because the shape of the vertical warp that occurs in the glass sheet is not uniform, when the first region of the glass sheet is contact-supported from the backside by the backside support member, the contact state between the two is not uniform in the vertical direction. Due to this contact state, the shape of the scribe line formation region is also not uniform in the vertical direction. Therefore, during the process of contacting the two and pressing the second region toward the backside, it becomes difficult to apply an appropriate bending stress uniformly to the scribe line formation region. As a result, chipping, cracking, etc. are likely to occur when the glass sheet is bent and broken.

[0007] From the above viewpoints, the present invention aims to prevent chipping, cracking, etc. by applying an appropriate bending stress uniformly to the area where the scribe line is formed when bending and breaking a glass plate in a vertical position using a back support member. [Means for solving the problem]

[0008] A first aspect of the present invention, which was invented to solve the above-mentioned problems, is a method for manufacturing a plate glass, which includes a bending and cutting step in which, for a plate glass in a vertical position in which a first region and a second region are arranged adjacent to each other in the width direction and a scribe line is formed on the front surface side of the boundary between the regions, the first region is contact-supported from the back surface side by a back surface support member, and a force toward the back surface side is applied to the second region to bend the plate glass along the scribe line and cut out the second region, and the bending and cutting step is characterized in that, by contacting the first region with the back surface support member, a curved portion is formed in the region where the scribe line is formed, which curves along the up-and-down direction and has a convex surface side.

[0009] Here, the scribe line formation region (hereinafter referred to as the scribe line formation region) means the part of the plate glass where the scribe line is formed and the surrounding area, for example, the area between the two parts separated by 50 to 100 mm on both sides of the scribe line in the width direction (the same applies hereinafter).

[0010] According to this method, when bending and breaking a glass sheet in a vertical position during the bending and breaking process, a curved portion is forcibly formed in the scribe line formation region by bringing the first region into contact with the back surface support member. Specifically, a curved portion that curves in the vertical direction so that the front surface side is convex is forcibly formed in the scribe line formation region. This forced formation of a curved portion ensures that the shape of the scribe line formation region during bending and breaking is uniformly determined. Furthermore, when a force toward the back surface is applied to the second region with the curved portion formed in the scribe line formation region, a bending stress greater than that in other regions acts uniformly around the apex of the curved portion in the scribe line formation region. This allows for the appropriate generation of cracks in the scribe line and the extension of the cracks during bending and breaking of the glass sheet. As a result, misalignment of the breaking position and poor breaking are less likely to occur when bending and breaking the glass sheet, and chipping, cracking, and other problems are suppressed.

[0011] In this method, the rear surface support member may have an intermediate convex portion for forming a curved portion along the vertical direction that is convex on the front surface side at a vertical intermediate portion of the scribe line formation region.

[0012] In this way, when the first region and the back surface support member are brought into contact, the presence of the intermediate convex portion of the back surface support member forms a curved portion in the vertical direction in the vertical middle of the scribe line formation region, with the front surface side being convex. In this state, when a force toward the back surface is applied to the second region, a greater bending stress can be applied to the vertical middle of the scribe line formation region than to other parts. As a result, when the glass sheet is bent and broken, a crack can be generated in the vertical middle of the scribe line and the crack can be properly extended to both the top and bottom. This more reliably prevents chipping, cracking, and the like.

[0013] In this method, the intermediate protrusion may be curved so that the length of the protrusion gradually decreases from the center toward both ends in the up-down direction.

[0014] In this way, the shape of the intermediate convex portion is smoothly curved, and therefore, when the first region is brought into contact with the back surface support member, the curved portion formed in the vertical middle portion of the scribe line formation region also has a smoothly curved shape, which makes it possible to break the glass sheet more accurately.

[0015] In this method, the intermediate protrusion may be disposed at a position that does not overlap in the up-down direction with a holding member that holds an upper end of the first region.

[0016] This prevents undue stress from acting around the upper end of the first region. Specifically, the upper end of the first region may become a flat portion when held by the holding member. In this case, if the intermediate convex portion and the holding member are positioned so as to overlap in the vertical direction, the curved portion in the vertical middle of the first region may interfere with the flat portion, causing undue stress that may cause twisting or the like around the upper end of the first region. This configuration avoids such problems.

[0017] In the above method, in the folding and cutting step, a pressing member disposed on the front surface side of the first region may press the first region against the back surface support member.

[0018] In this way, the first region is sandwiched between the pressing member and the back surface support member, which prevents the glass sheet from shaking when forming the curved portion in the scribe line formation region, thereby stabilizing the contact state between the first region and the back surface support member.

[0019] In this method, the pressing member may have an upper convex portion for forming a flat portion at the upper end of the scribe line forming region.

[0020] In this way, when the pressing member presses the first region against the back surface support member, the upper convex portion of the pressing member forms a flat portion at the upper end of the scribe line formation region, thereby ensuring the pressing by the pressing member. As a result, the contact state between the first region and the back surface support member can be further reliably stabilized.

[0021] In this method, the upper convex portion may be disposed at a position that overlaps in the vertical direction with a holding member that holds an upper end portion of the first region.

[0022] In this way, the flat portion formed in the first region by sandwiching the upper convex portion of the pressing member and the back surface support member, and the flat portion formed in the first region by holding with the holding member, can be aligned along the width direction at the upper end of the first region, thereby more reliably preventing undue stress from acting around the upper end of the first region.

[0023] In this method, the back surface support member may have an intermediate convex portion in the vertical middle portion of the scribe line formation area for forming a curved portion along the vertical direction with the front surface side being convex, and the upper convex portion may be arranged in a position that does not overlap with the intermediate convex portion in the vertical direction.

[0024] This prevents interference between the flat portion formed at the upper end of the first region by sandwiching the upper convex portion of the pressing member and the back surface support member, and the curved portion formed at the vertically intermediate portion of the first region by sandwiching the intermediate convex portion of the back surface support member and the pressing member, thereby preventing undue stress from acting on the periphery between the upper end and the vertically intermediate portion of the first region.

[0025] In this method, the pressing member may have a lower convex portion for forming a flat portion at the lower end of the scribe line forming region.

[0026] In this way, when the pressing member presses the first region against the back surface support member, the lower convex portion of the pressing member forms a flat portion at the lower end of the scribe line formation region, thereby ensuring the pressing by the pressing member. As a result, the contact state between the first region and the back surface support member can be further reliably stabilized.

[0027] In this method, the back surface support member may have an intermediate convex portion in the vertical middle of the scribe line formation area for forming a curved portion along the vertical direction with the front surface side being convex, and the lower convex portion may be arranged in a position that does not overlap with the intermediate convex portion in the vertical direction.

[0028] This prevents interference between the flat portion formed at the lower end of the first region by sandwiching the lower convex portion of the pressing member and the back surface support member, and the curved portion formed at the vertically intermediate portion of the first region by sandwiching the intermediate convex portion of the back surface support member and the pressing member, thereby preventing undue stress from acting on the periphery between the lower end and the vertically intermediate portion of the first region.

[0029] A second aspect of the present invention, which was devised to solve the above-mentioned problems, is a plate glass manufacturing apparatus including a breaking device configured to take a vertically oriented plate glass in which a first region and a second region are arranged adjacent to each other in the width direction and a scribe line is formed on the front surface side of the boundary between the regions, and to break the plate glass along the scribe line and cut out the second region by applying a force toward the back surface side to the second region while supporting the first region in contact with the back surface side by a back surface support member, and characterized in that the breaking device is configured to form a curved portion in the scribe line formation region that extends along the up-down direction and has a convex surface side by bringing the first region into contact with the back surface support member.

[0030] This makes it possible to obtain the same effects as those of the previously described manufacturing method, which has substantially the same configuration as this manufacturing apparatus.

[0031] A third aspect of the present invention, which has been devised to solve the above problems, is a rectangular glass plate having two first sides extending in a first direction and two second sides extending in a direction different from the first direction, characterized in that the glass plate has a plurality of streaks extending in the first direction on the front and / or back surface, and has a crack origin within a range of 25% to 75% of the total length of at least one of the first sides from one end to the other end. Here, the crack origin refers to the starting point of a crack.

[0032] According to this configuration, since the crack origin is present within a predetermined range in the longitudinal center of the side of the glass sheet, when the glass sheet is cut, the crack propagates from the longitudinal center of the glass sheet toward both longitudinal ends. In other words, a crack origin is formed in the longitudinal center of the side of the glass sheet, and the crack propagates smoothly from this origin toward both longitudinal ends. Therefore, the glass sheet is properly cleaved, and adhesion of glass powder to the glass sheet due to poor cleaving, etc. is prevented, resulting in high quality. [Effects of the Invention]

[0033] According to the present invention, when bending and breaking a glass plate in a vertical position using a rear support member, it is possible to apply an appropriate bending stress uniformly to the scribe line formation area, thereby preventing chipping, cracking, etc. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a perspective view showing a main part of a cleaving device included in an apparatus for manufacturing a glass sheet according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a longitudinal sectional side view taken along line BB in FIG. [Figure 3] FIG. 2 is a perspective view showing the operation of a cleaving device included in the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a longitudinal sectional side view taken along line CC in FIG. 3. [Figure 5] 1 is a vertical cross-sectional side view showing a main part of a cleaving device included in an apparatus for manufacturing a glass sheet according to an embodiment of the present invention. [Figure 6a] 1A to 1C are cross-sectional bottom views of essential parts showing, in time sequence, the procedure for breaking a glass sheet using a breaking device included in the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 6b] 1A to 1C are cross-sectional bottom views of essential parts showing, in time sequence, the procedure for breaking a glass sheet using a breaking device included in the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 6c] 1A to 1C are cross-sectional bottom views of essential parts showing, in time sequence, the procedure for breaking a glass sheet using a breaking device included in the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 7] 1 is a cross-sectional bottom view of a main part showing the overall configuration of a cleaving device included in a plate glass manufacturing apparatus according to an embodiment of the present invention. [Figure 8] 1 is a schematic perspective view of a glass sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, a method and apparatus for manufacturing a glass sheet, and a glass sheet according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0036] FIG. 1 illustrates a breaking device 1 included in a glass sheet manufacturing apparatus according to an embodiment of the present invention. As shown in the figure, a glass sheet G has a first region G1 and a second region G2 arranged adjacent to each other in the width direction. In this embodiment, the first region G1 is a region that will become the finished product of the glass sheet G and has a uniform thickness throughout. The second region G2 is a region that will be cut out from the glass sheet G and discarded, and has an edge portion Ge at the outer end in the width direction (the left end in the figure) that is thicker than the first region G1. A scribe line S is formed on the front surface Ga, Gx side of the boundary between the first region G1 and the second region G2. In the figure, the scribe line S does not reach the upper and lower ends of the glass sheet G. Note that the scribe line S may reach these ends. In the following description, for convenience, the first region G1 will be referred to as the effective region, and the second region G2 will be referred to as the unnecessary region. Although not shown, numerous vertically extending streaks are formed on the front surface Ga, Gx and / or back surface Gb, Gy of the glass sheet G. These streaks are formed along the drawing direction when the glass sheet G is manufactured by, for example, the overflow method. These streaks can be observed as striped patterns by irradiating the glass sheet G with light from a light source (e.g., a xenon light) while adjusting the angle in a darkroom and projecting the transmitted light onto a screen.

[0037] The glass sheet G is suspended and supported in a vertical position so that the scribe line S faces the up-down direction. The thickness of the glass sheet G (thickness of the region excluding the edge portions Ge) is, for example, 50 to 2000 μm, with the upper limit of this thickness preferably being 500 μm, and more preferably 400 μm. In this embodiment, the glass sheet G is flexible. The glass sheet G has warpage in the vertical direction. The specific shape of the warpage is a shape in which the scribe line S on the surfaces Ga and Gx of the glass sheet G and any imaginary line parallel to the scribe line S are curved. Furthermore, the shape of the vertical warpage that occurs in the glass sheet G is not uniform but is random.

[0038] The breaking device 1 breaks the glass sheet G along the scribe line S to remove the unnecessary region G2. More specifically, the breaking device 1 includes a gripping mechanism 2 that grips the upper end of the effective region G1, a back surface support member 3 arranged on the back surface Gb side of the effective region G1, a pressing member 4 arranged opposite the back surface support member 3 on the front surface Ga side of the effective region G1, a suction mechanism 5 arranged on the back surface Gy side of the unnecessary region G2, and a pushing member 6 arranged opposite the suction mechanism 5 on the front surface Gx side of the unnecessary region G2.

[0039] The gripping mechanism 2 has a pair of gripping pieces 2a and a drive unit 2b that moves the pair of gripping pieces 2a toward and away from each other. The configuration of the drive unit 2b is not limited to that shown in the illustration. The pair of gripping pieces 2a grip the upper end of the effective area G1 by approaching each other to a closed state, and release the grip of the upper end of the effective area G1 by moving away from each other to an open state. The pair of gripping pieces 2a may be configured to be in the open state by spreading their legs apart and in the closed state by closing their legs. Here, spreading their legs means that the pair of gripping pieces 2a rotate around a fulcrum (support shaft) in an opening direction, and closing their legs means that the pair of gripping pieces 2a rotate around a fulcrum (support shaft) in a closing direction.

[0040] The gripping mechanism 2 is slidably held on a rail (not shown) that extends above the glass sheet G in the width direction, and serves to transport the glass sheet G to the breaking position. When breaking the glass sheet G at the breaking position, the gripping mechanism 2 stops while gripping the upper end of the effective region G1. In this case, the lower end of the glass sheet G is not held and is left open. The gripping mechanism 2 grips the upper end of the effective region G1 at multiple locations in the width direction (two locations in this embodiment (one location is not shown)).

[0041] The back surface support member 3 contacts and supports the effective area G1 from the back surface Gb side when breaking the glass sheet G, and is disposed at the end of the effective area G1 on the scribe line S side. The back surface support member 3 moves toward and away from the back surface Gb of the effective area G1 by the operation of a driving means (not shown), such as a fluid pressure cylinder such as an air cylinder, a ball screw mechanism, or a robot arm. The back surface support member 3 is a vertically elongated columnar or plate-like body (surface plate). The widthwise separation distance between the back surface support member 3 and the scribe line S (the separation distance when the back surface support member 3 contacts the effective area G1) is, for example, 10 to 30 mm, and preferably 10 to 20 mm. In the illustrated example, the back surface support member 3 extends from the upper and lower ends of the effective area G1, but it does not have to extend from these upper and lower ends.

[0042] The pressing member 4 presses the effective area G1 against the rear surface support member 3 when breaking the glass sheet G. The pressing member 4 moves toward and away from the surface Ga of the effective area G1 by the operation of a driving means (not shown) such as a fluid pressure cylinder such as an air cylinder, a ball screw mechanism, or a robot arm. In this embodiment, the pressing member 4 is a columnar or plate-like body that is long in the vertical direction. The vertical length of the pressing member 4 is the same as that of the rear surface support member 3 described above.

[0043] The suction mechanism 5 includes a vertically elongated holding base 5a and suction pads 5b attached to the upper and lower ends of the holding base 5a. The holding base 5a rotates (e.g., in the direction of arrow A) by the operation of a driving means (not shown), such as a robot arm. The suction pads 5b suction-hold the back surface Gy of the unnecessary region G2 by negative pressure and are made of an elastic material such as stretchable rubber or resin. The upper suction pad 5b is disposed at a height approximately equal to that of the gripping piece 2a that grips the upper end of the effective region G1. The lower suction pad 5b is disposed at a lower position, spaced apart from the vertical center of the glass plate G by approximately the same length as the upper suction pad 5b. Three or more suction pads 5b may be arranged vertically on the holding base 5a, but only two suction pads arranged at the same positions as shown in the figure are actually used to suction-hold the back surface Gy of the unnecessary region G2.

[0044] The pressing member 6 has a flat portion 6a (see FIG. 5) that contacts the front surface Gx of the unnecessary region G2, and in this embodiment, is a plate-like member that is elongated in the vertical direction. The pressing member 6 rotates (for example, in the direction of arrow A) by the operation of a driving means (not shown) such as a robot arm, thereby applying a pressing force to the unnecessary region G2 toward the back surface Gy. In the illustrated example, the pressing member 6 extends from the upper and lower ends of the unnecessary region G2, but it does not have to extend from these upper and lower ends.

[0045] 2 is a longitudinal sectional side view taken along line BB in FIG. 1. As shown in the figure, the rear surface support member 3 has an intermediate convex portion 7 in the vertical center of a facing portion 3x that faces the rear surface Gb of the glass sheet G (effective area G1). More specifically, the rear surface support member 3 has a columnar or plate-shaped support base 3y. A curved intermediate convex portion 7 is fixed to the surface of the support base 3y. The intermediate convex portion 7 is smoothly curved so that the length of its protrusion from the vertical center to both ends gradually decreases. The intermediate convex portion 7 serves to form a curved portion Gw (details will be described later) that extends vertically and is convex on the surfaces Ga and Gx sides, in the vertical center of the scribe line formation area Gs.

[0046] The vertical length of the intermediate protrusion 7 is ¼ to ¾ of the vertical length of the glass sheet G. The intermediate protrusion 7 is positioned so as not to overlap the gripping piece 2a that grips the upper end of the effective region G1 in the vertical direction. That is, the upper end 7x of the intermediate protrusion 7 is located below the lower end 2y of the gripping piece 2a. The lower end 7y of the intermediate protrusion 7 is located below the vertical center of the glass sheet G by a distance approximately equal to the upper end 7x of the intermediate protrusion 7. The intermediate protrusion 7 is softer than the glass sheet G and the supporting substrate 3y and has excellent elasticity and cushioning properties. For example, it is made of a porous or foamed resin such as plastic corrugated cardboard or Paronia, or FC nylon. A covering sheet 8 is attached to the surfaces of the supporting substrate 3y and the intermediate protrusion 7 to cover them. This covering sheet 8 is softer than the intermediate protrusion 7 and is made of a porous or foamed resin such as sponge or low-resilience sponge.

[0047] The pressing member 4 has an upper convex portion 9 at the upper end of a facing portion 4x facing the surface Ga of the glass sheet G (effective area G1), and a lower convex portion 10 at the lower end of the facing portion 4x. More specifically, the pressing member 4 has a columnar or plate-shaped supporting substrate 4y. The upper convex portion 9 and the lower convex portion 10 are fixedly provided at two locations, upper and lower, on the surface of the supporting substrate 4y. The upper convex portion 9 and the lower convex portion 10 are both wedge-shaped, protruding from the center of the supporting substrate 4y in the vertical direction toward both ends and gradually increasing in length. The upper convex portion 9 and the lower convex portion 10 serve to form an upper flat portion Gcs and a lower flat portion Gds (details will be described later) at the upper and lower ends, respectively, of the scribe line formation region GS.

[0048] The upper protrusion 9 and the lower protrusion 10 are both arranged at positions that do not overlap with the middle protrusion 7 of the back surface support member 3 in the vertical direction. That is, the lower end 9y of the upper protrusion 9 is located above the upper end 7x of the middle protrusion 7, and the upper end 10x of the lower protrusion 10 is located below the lower end 7y of the middle protrusion 7. The upper protrusion 9 is also arranged at a position that overlaps with the gripping piece 2a that grips the upper end of the effective area G1 in the vertical direction. That is, the upper end 9x of the upper protrusion 9 is located above the upper end 2x of the gripping piece 2a, and the lower end 9y of the upper protrusion 9 is located below the lower end 2y of the gripping piece 2a. The upper protrusion 9 may also be arranged at a position that overlaps with the gripping piece 2a only partially in the vertical direction. In this embodiment, the upper end 9x of the upper convex portion 9 and the lower end 10y of the lower convex portion 10 are located at the same height as the upper and lower ends of the glass sheet G, respectively. However, these convex portions 9, 10 may or may not protrude from the upper and lower ends of the glass sheet G, respectively. The upper convex portion 9 and the lower convex portion 10 are both softer than the glass sheet G and the supporting substrate 4y and have excellent elasticity or cushioning properties. For example, they are made of plastic corrugated cardboard, porous resin or foamed resin such as Paronia (registered trademark), or FC nylon. A covering sheet 11 is attached to the surfaces of the supporting substrate 4y, the upper convex portion 9, and the lower convex portion 10 to cover them. This covering sheet 11 is softer than the upper convex portion 9 and the lower convex portion 10 and is made of, for example, porous resin or foamed resin such as sponge or low-resilience sponge.

[0049] Next, a method for manufacturing a glass sheet using the manufacturing apparatus configured as above will be described.

[0050] First, in a process upstream of the position shown in FIG. 1 , a glass sheet G is suspended and supported by a gripping mechanism 2, and a scribe line S is formed on the glass sheet G by pressing with a wheel cutter, irradiating with a laser, or the like. Specifically, a scribe line S is formed on the front surface Ga and Gx sides of the boundary between the effective region G1 and the unnecessary region G2 of the glass sheet G. Next, the glass sheet G with the scribe line S formed thereon is transported widthwise while suspended and supported by the gripping mechanism 2, until the glass sheet G reaches the breaking position shown in FIG. 1 . At this point, the pressing member 4 and the back surface support member 3 are spaced apart from the front surface Ga and back surface Gb of the effective region G1, respectively, and the pushing member 6 and suction mechanism 5 are also spaced apart from the front surface Gx and back surface Gy of the unnecessary region G2, respectively. In this state, vertical warping occurs in the glass sheet G.

[0051] After this, the back surface support member 3 moves toward the effective area G1, and the pressing member 4 also moves toward the effective area G1. When the movements of the back surface support member 3 and the pressing member 4 are completed, the pressing member 4 presses the effective area G1 against the back surface support member 3. As a result, as shown in FIG. 3, a curved portion Gw is formed in the pressed portion of the effective area G1 (hereinafter referred to as the pressed portion) (see FIG. 4 for details), and a curved portion Gws is also formed in the scribe line formation area Gs. More specifically, curved portions Gw and Gws are formed in the vertical centers of the pressed portion and the scribe line formation area Gs, respectively, so that the surfaces Ga and Gx are convex along the vertical direction. In this embodiment, a similar curved portion Gwt is also formed in the vertical center of the unnecessary area G2, and further, a similar curved portion Gwu is also formed in the vertical center of the peripheral area of ​​the gripping portion of the effective area G1 by the gripping piece 2a. In addition, when the pressing member 4 presses the effective area G1 against the back surface support member 3, an upper planar portion Gc and a lower planar portion Gd are formed at the upper and lower ends of the pressed area, respectively (see FIG. 4 for details), and accordingly, an upper planar portion Gcs and a lower planar portion Gds are also formed at the upper and lower ends of the scribe line formation area Gs, respectively. In this embodiment, similar upper planar portions Gct and lower planar portions Gdt are also formed at the upper and lower ends of the unnecessary area G2, respectively, and further similar upper planar portions Gcu and lower planar portions Gdu are also formed at the upper and lower ends of the peripheral area of ​​the gripped portion of the effective area G1 by the gripping pieces 2a.

[0052] FIG. 4 is a longitudinal cross-sectional view taken along line CC in FIG. 3. As shown in the figure, a curved portion Gw is formed in the vertical center of the effective region G1 (pressing portion) by contact with the intermediate convex portion 7. More specifically, the curved portion Gw is smoothly curved so that the degree of convexity toward the surface Ga gradually decreases from the vertical center toward both ends. As a result, the vertical warp that occurred in the vertical center of the effective region G1 disappears. Furthermore, an upper flat portion Gc and a lower flat portion Gd are formed at the upper and lower ends of the effective region G1 by contact with the upper convex portion 9 and the lower convex portion 10, respectively. As a result, the warp that occurred in the upper and lower ends of the effective region G1 also disappears. In this case, the lower end of the upper flat portion Gc is located at a height approximately equal to the lower end 2y of the gripping piece 2a. As shown in the same figure, when the effective area G1 is sandwiched between the back support member 3 and the pressing member 4, the middle convex portion 7 is only slightly compressed and deformed, whereas the upper convex portion 9, the lower convex portion 10 and the covering sheets 8 and 11 are greatly compressed and deformed.

[0053] In this state, the suction mechanism 5 moves toward the unnecessary region G2, and the pushing member 6 also moves toward the unnecessary region G2. When the movements of the suction mechanism 5 and the pushing member 6 are completed, as shown in Figure 5, the two suction pads 5b of the suction mechanism 5 suction-hold the back surface Gy of the unnecessary region G2, and the pushing member 6 comes into contact with the front surface Gx of the unnecessary region G2. In this case, the two suction pads 5b suction-hold the upper flat portion Gct and the lower flat portion Gdt of the unnecessary region G2. The pushing member 6 comes into contact with the periphery of the top of the curved portion Gwt formed in the vertical center of the unnecessary region G2.

[0054] 6a, 6b, and 6c show the subsequent steps of breaking the glass sheet G. Each of these figures is a cross-sectional bottom view of the essential parts of the breaking device 1 and the essential parts of the glass sheet G, viewed from below. FIG. 6a shows the initial stage of the breaking process, in which the scribe line formation region Gs and the unnecessary region G2 of the glass sheet G are forced into the shapes described above. From this state, as shown in FIG. 6b, by rotating the suction mechanism 5 and the pushing member 6 in the direction of arrow A, the pushing member 6 applies a pushing force to the unnecessary region G2 toward the back surface Gy. As a result, the unnecessary region G2 is bent toward the back surface Gy with the back surface support member 3 as a fulcrum. Note that the suction mechanism 5 does not substantially apply a pulling force to the unnecessary region G2 toward the back surface Gy. During this process, the scribe line formation region Gs is curved in the width direction, resulting in a bending stress acting on the scribe line formation region Gs. At this stage, a curved portion Gw is formed in the vertical center of the scribe line formation region Gs. Therefore, the largest bending stress acts on the vertical center of the scribe line formation region Gs. Thereafter, as the suction mechanism 5 and the pressing member 6 continue to rotate, the bending stress acting on the scribe line formation region Gs becomes sufficiently large, and the glass sheet G is broken along the scribe line S, as shown in FIG. 6c. After the glass sheet G is broken and the unnecessary region G2 is cut out, the unnecessary region G2 is transported to a retracted position while being held by the holding mechanism 2, and then the holding by the holding mechanism 2 is released and the unnecessary region G2 is dropped and collected.

[0055] The above-described glass sheet breaking device 1 and breaking process have been described with reference to an unnecessary region G2 at one widthwise end of the glass sheet G. However, the unnecessary region G2 is typically formed at both widthwise ends of the glass sheet G. To break the glass sheet G to remove the unnecessary region G2, the following configuration is adopted. That is, as shown in FIG. 7 , the glass sheet G has an effective region G1 at its widthwise center and unnecessary regions G2 on both sides of the effective region G1. Scribe lines S are formed at the two boundaries between the effective region G1 and each unnecessary region G2. The glass sheet G is broken along these two scribe lines S by a glass sheet breaking device 1 disposed corresponding to each unnecessary region G2. Each of these two glass sheet breaking devices 1 has a pressing member 4 and a back surface support member 3 disposed on the front surface Ga and back surface Gb sides of the effective region G1, respectively, and a pressing member 6 and a suction mechanism 5 disposed on the front surface Gx and back surface Gy sides of the unnecessary region G2, respectively. The pushing member 6 and the suction mechanism 5 are configured to rotate in the direction of arrow A at both locations. The detailed configuration of the two cutting devices 1 is the same as that of the above-described cutting device 1. In this case, the two cutting devices 1 may perform cutting simultaneously, or one cutting device 1 may complete cutting before the other cutting device 1 performs cutting. Alternatively, one cutting device 1 and the other cutting device 1 may be disposed at a distance longer than the width of the glass sheet G, and after one unnecessary region G2 is broken and removed by one cutting device 1, the glass sheet G may be moved in the width direction, and then the other unnecessary region G2 may be broken and removed by the other cutting device 1. Furthermore, separately from this, a single bending / cutting device 1 may be used, and one unnecessary area G2 may be bent / cut and removed by the bending / cutting device 1, and then the glass plate G may be rotated 180 degrees in a planar view, and then the other unnecessary area G2 may be bent / cut and removed by the bending / cutting device 1.

[0056] FIG. 8 is a perspective view showing a rectangular glass sheet G (effective area G1) cut out by such an operation. As shown in the figure, the glass sheet G has two sides 12x extending in a first direction and two sides 12y extending in a direction different from the first direction (in the illustrated example, a direction perpendicular to the first direction). These four sides 12x and 12y also form the four end faces of the glass sheet G. One side (one end face) 12x extending in the first direction has a crack origin D formed due to contact between the pressing member 4 and the intermediate protrusion 7. This crack origin D exists within a range (Lxx) of 25% to 75% of the total length Lx of the side 12x from one end 12xa to the other end 12xb. In the illustrated example, the crack origin D exists only in one side 12x extending in the first direction; however, similar crack origins may also exist in the other sides 12x extending in the first direction. This first direction is along the drawing direction. Therefore, a plurality of streaks extending in the first direction are present on one surface 12za or the other surface 12zb of the front and back surfaces of the glass sheet G, or on both surfaces 12za and 12zb. In this embodiment, the crack origin D is formed on the edge 12x, with one end (the upper end in the illustrated example) of one surface 12za of the front and back surfaces of the glass sheet G, and does not reach the other surface 12zb of the glass sheet G. Here, the one surface 12za corresponds to the back surface of the glass sheet G (a surface of lower quality than the front surface). Note that the crack origin D can be identified or estimated by a method of confirming it with an electron microscope, or, if it cannot be confirmed with an electron microscope, by a method of estimating it from rib marks or Wallner lines that appear on the glass sheet G. For example, the closer to the position of the crack origin D, the narrower the spacing between adjacent rib marks. Therefore, the position of the crack origin D can be estimated based on the spacing between the rib marks. It is preferable that the crack origin D is located within a range (Lxx) of 30% to 70% of the total length Lx of the edge 12x from one end 12xa to the other end 12xb, and it is more preferable that the crack origin D is located within a range (Lxx) of 35% to 65% of the total length Lx.

[0057] The multiple streaks that occur along the sheet drawing direction can be observed as striped patterns by adjusting the angle of the sheet glass G in a darkroom, shining light from a light source (e.g., a xenon light), and projecting the transmitted light onto a screen.

[0058] According to the glass sheet manufacturing apparatus according to the embodiment of the present invention configured as described above and the glass sheet manufacturing method using the same, the following effects can be obtained.

[0059] In the above embodiment, when bending and breaking a vertically oriented glass sheet G in the bending and breaking process, the effective area G1 and the back surface support member 3 are brought into contact with each other to forcibly form a curved portion Gws in the scribe line formation area Gs. By forcibly forming this curved portion Gws, the shape of the scribe line formation area Gs during bending and breaking is uniformly determined to have a curved portion Gws formed in the vertical center that is convex toward the front surfaces Ga and Gx. In this state, when a force toward the back surface Gy is applied to the unnecessary area G2, a greater bending stress can be uniformly applied to the vertical center of the scribe line formation area Gs than to other areas. This allows a crack origin to be generated in the vertical center of the scribe line S when bending and breaking the glass sheet G, and the crack origin can be properly extended toward both the top and bottom. As a result, when bending and breaking the glass sheet G, misalignment of the breaking position or breaking defects are less likely to occur, and chipping and cracking are suppressed.

[0060] In the above embodiment, in the folding and splitting process, the effective area G1 is sandwiched between the pressing member 4 and the back surface support member 3, which prevents the glass sheet G from shaking when the curved portion Gws is forcibly formed in the scribe line formation area Gs. This stabilizes the contact state between the effective area G1 and the back surface support member 3.

[0061] In the above embodiment, since the shape of the intermediate convex portion 7 is smoothly curved, the curved portion Gws formed in the vertical center of the scribe line formation area Gs also has a smoothly curved shape, making it possible to fold and break the glass sheet more appropriately.

[0062] In the above embodiment, the intermediate protrusion 7 is positioned so as not to overlap vertically with the gripping piece 2a that grips the upper end of the effective region G1, thereby preventing undue stress from acting around the upper end of the effective region G1. More specifically, if the intermediate protrusion 7 and the gripping piece 2a were positioned so as to overlap vertically, the curved portion Gw in the vertical center of the effective region G1 would interfere with the flat portion (near Gcu) formed by the gripping piece 2a at the upper end of the effective region G1, potentially causing undue stress that could cause twisting or the like around the upper end of the effective region G1. According to the above embodiment, such a problem can be avoided.

[0063] In the above embodiment, the upper convex portion 9 is disposed at a position that overlaps the gripping piece 2a in the vertical direction, so that the upper flat portion Gc at the pressing portion of the effective area G1 and the flat portion formed in the effective area G1 by the gripping piece 2a are aligned along the width direction at the upper end of the effective area G1, thereby more reliably preventing undue stress from acting around the upper end of the effective area G1.

[0064] In the above embodiment, the intermediate convex portion 7 is disposed at a position that does not overlap the upper convex portion 9 and the lower convex portion 10 in the vertical direction, so that the curved portion Gw in the vertical center of the effective region G1 does not interfere with either the upper flat portion Gc or the lower flat portion Gd of the effective region G1. As a result, it is possible to prevent undue stress from acting on the periphery between the vertical ends and the vertical center of the effective region G1.

[0065] In the above embodiment, since a curved portion Gwt is also formed in the vertical center of the unneeded region G2, the pressing force of the pressing member 6 can be concentrated on the vertical center of the unneeded region G2. Therefore, with the action of this concentrated pressing force, a greater bending stress can be applied to the vertical center of the scribe line formation region Gs. As a result, it is possible to more appropriately generate a crack in the vertical center of the scribe line S and extend the crack to both the top and bottom.

[0066] The above describes the method for manufacturing a sheet glass, the apparatus for manufacturing a sheet glass, and the sheet glass according to an embodiment of the present invention, but the present invention is not limited to this, and various variations are possible within the scope of the gist of the present invention.

[0067] In the above embodiment, the second region G2 is an unnecessary region having an ear portion Ge, but the second region G2 may be an unnecessary region without an ear portion or an effective region that will become a product (an effective region with the same plate thickness as the first region G1).

[0068] In the above embodiment, the curved portion Gws is forcibly formed in the scribe line formation region Gs using the back surface support member 3 and the pressing member 4, but the curved portion Gws may be forcibly formed in the scribe line formation region Gs simply by bringing the back surface Gb of the first region G1 into contact with the back surface support member 3 without using the pressing member 4. In this case, in the initial stage of the bending and cutting process, a force toward the back surface Gy is applied to the second region G2 to forcibly form the curved portion Gws in the scribe line formation region Gs, and in this state, a force toward the back surface Gy is further applied to the second region G2.

[0069] In the above embodiment, the intermediate protrusion 7 is provided in the vertical center of the facing portion 3x of the back surface support member 3, but the intermediate protrusion 7 may be provided in a position offset upward or downward from the vertical center as long as it is in the vertical intermediate portion of the facing portion 3x of the back surface support member 3. Accordingly, the curved portion Gws of the scribe line formation region Gs is not limited to being formed in the vertical central portion, and may be formed in a position offset upward or downward from the vertical center as long as it is in the vertical intermediate portion (the same applies to the other curved portions Gw, Gws, Gwt, Gwu).

[0070] In the above embodiment, the case where the entire second region G2 is curved into the predetermined shape has been exemplified, but as long as the scribe line formation region Gs is curved into the predetermined shape, the periphery of the outer end of the second region G2 in the width direction does not have to be curved into the predetermined shape. Moreover, the peripheral region of the gripping portion of the effective region G1 held by the gripping pieces 2a does not have to be curved into the predetermined shape.

[0071] In the above embodiment, the pushing member 6 and the suction mechanism 5 are used to apply a pushing force to the second region G2 toward the back surface Gy. However, the pushing member 6 may be omitted and the suction mechanism 5 may be used to apply a pulling force to the second region G2 toward the back surface Gy. Furthermore, the pushing member 6 and the suction mechanism 5 are used to apply a pushing force to the second region G2 toward the back surface Gy. However, instead of the pushing member, a member that pulls the second region toward the back surface Gy may be used. Alternatively, the upper and lower ends of the second region G2 may be held by holding members such as gripping pieces, and the holding members may be moved toward the back surface G to apply a force to the second region G2 toward the back surface Gy. In the above embodiment, the shape of the pushing member 6 is not limited to a plate shape having a flat portion 6a. It may also be a rectangular column shape having a flat portion, or a columnar or round bar shape without a flat portion.

[0072] In the above embodiment, the upper end of the first region G1 is held by the gripping piece 2a of the gripping mechanism 2, but instead, it may be held by another holding member such as a suction cup. [Explanation of symbols]

[0073] 1. Sheet glass manufacturing equipment (breaking equipment) 2 Gripping mechanism 2a Grip piece 3 Back support member 4 Presser member 5 Adsorption mechanism 5b Suction pad 6 Push-in member 7 Middle convex part 9 Upper convex part 10 Lower convex part D Crack Origin G Plate glass G1 First area (effective area) Ga first region surface Gb Back side of the first area G2 2nd area (unnecessary area) Gx Second region surface Gy Back side of the second region Gs Scribe line formation area (Scribe line formation area) Gws Curved part (curved part of the scribe line formation area) Gcs flat part (upper flat part of the scribe line formation area) Gds flat surface (flat surface below the scribe line formation area) S scribe line

Claims

1. A method for manufacturing a glass sheet, comprising: a bending and splitting step of: for a glass sheet in a vertical orientation in which a first region and a second region are arranged adjacent to each other in the width direction and a scribe line is formed on the front surface side of a boundary between the regions; the first region is supported in contact with the rear surface side by a rear surface support member; and a force toward the rear surface side is applied to the second region to bend the glass sheet along the scribe line, thereby cutting out the second region; In the bending and splitting step, the first region is brought into contact with the back surface support member, thereby forming a curved portion in the scribe line formation region along the vertical direction, with the front surface side being convex.

2. The method for manufacturing a glass sheet according to claim 1, wherein the rear surface support member has an intermediate convex portion for forming a curved portion along the vertical direction that is convex on the front surface side at a vertical intermediate portion of the scribe line formation region.

3. 3. The method for manufacturing a glass sheet according to claim 2, wherein the intermediate convex portion is curved so that the length of the convex portion protruding from the center in the up-down direction toward both ends gradually decreases.

4. The method for manufacturing a glass sheet according to claim 2 or 3, wherein the intermediate convex portion is disposed at a position that does not overlap in the up-down direction with a holding member that holds an upper end portion of the first region.

5. The method for manufacturing a sheet glass according to any one of claims 1 to 4, wherein in the bending step, a pressing member arranged on the front surface side of the first region presses the first region against the back surface support member.

6. The method for manufacturing a glass sheet according to claim 5, wherein the pressing member has an upper convex portion for forming a flat portion at an upper end of the region where the scribe line is formed.

7. The method for manufacturing a glass sheet according to claim 6 , wherein the upper convex portion is disposed at a position that overlaps in the vertical direction with a holding member that holds an upper end portion of the first region.

8. the rear surface support member has an intermediate convex portion at a vertical intermediate portion of the scribe line formation region for forming a curved portion along the vertical direction in which the front surface side is convex, The method for manufacturing a glass sheet according to claim 6 or 7, wherein the upper convex portion is disposed at a position where it does not overlap with the intermediate convex portion in the up-down direction.

9. 9. The method for manufacturing a glass sheet according to claim 5, wherein the pressing member has a lower convex portion for forming a flat portion at a lower end of the region where the scribe line is formed.

10. the rear surface support member has an intermediate convex portion at a vertical intermediate portion of the scribe line formation region for forming a curved portion along the vertical direction in which the front surface side is convex, The method for manufacturing a glass sheet according to claim 9 , wherein the lower convex portion is disposed at a position that does not overlap the middle convex portion in the up-down direction.

11. A glass sheet manufacturing apparatus including a breaking device configured to break a glass sheet in a vertical orientation, in which a first region and a second region are arranged adjacent to each other in the width direction and a scribe line is formed on the front surface side of a boundary between the regions, by applying a force to the second region toward the back surface side while supporting the first region in contact with the back surface side with a back surface support member, thereby breaking the glass sheet along the scribe line and cutting out the second region, The bending and cutting device is configured to form a curved portion in the scribe line formation area that extends in the vertical direction and has a convex surface side by bringing the first area into contact with the back surface support member.

12. A rectangular glass sheet having two first sides extending in a first direction and two second sides extending in a direction different from the first direction, a plurality of stripes extending in the first direction on the front surface and / or the back surface; At least one of the first sides has one crack origin within a range of 25% to 75% of the total length from one end to the other end of the first side, The crack origin is a starting point from which a crack propagates when the glass plate is bent and broken.

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