Method for manufacturing glass plates, glass plates, and glass plate packaging.

Abstract

To prevent a damage of a glass plate loaded on a pallet in an upright orientation.SOLUTION: A method of manufacturing a glass plate includes a cutting step S3 of removing an end part Ga of a glass plate G1 in a width direction with the glass plate G1 supported in an upright orientation. The cutting step S3 includes a scribing step, and a bending and dividing step. In the scribing step, a scribe line SL2 is formed so that a maximum depth of a median crack MC in an intermediate part MP1 of the scribe line SL2 is shallower than that in a bottom part BP1 of the scribe line SL2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a glass plate, a glass plate, and a glass plate package.

Background Art

[0002] As is well known, for example, in displays such as liquid crystal displays and organic EL displays, a glass plate is used as a glass substrate or a cover glass. As a method for manufacturing a glass plate, a method using a down-draw method typified by an overflow down-draw method, a slot down-draw method, and a redraw method is widely adopted. As an example of a method for manufacturing a glass plate using the overflow down-draw method, the following can be cited.

[0003] In the method for manufacturing a glass plate, as disclosed in Patent Document 1, a forming step of forming a glass ribbon and a first cutting step (X cutting step) of cutting out a glass plate from the formed glass ribbon by scribing are performed.

[0004] In the forming step, molten glass is supplied to an overflow groove provided at the top of a wedge-shaped forming body and caused to overflow. The overflowed molten glass is caused to flow down along the side surface of the forming body, and then fused and integrated at the lower end of the forming body. Thereby, a plate-shaped glass ribbon is formed. Thereafter, the formed glass ribbon is drawn downward while being sandwiched from both the front and back sides by a pair of rollers arranged in a plurality of upper and lower stages. Ears having a thickness larger than that of the central portion in the width direction are formed at both ends in the width direction of the glass ribbon thus obtained.

[0005] The scribing performed in the first cutting step forms a scribing line along the width direction on the main surface of the glass ribbon conveyed downward, curves the peripheral region of the scribing line to apply bending stress, and cuts the glass ribbon along the scribing line. Thereby, a rectangular glass plate is cut out from the glass ribbon.

[0006] Next, in the method for manufacturing the glass plate, as disclosed in Patent Document 2, a second cutting step (Y cutting step) is performed in which the edges formed on both ends in the width direction of the glass plate are removed by scribe cutting.

[0007] In the second cutting step, scribe cutting is performed to form a scribe line along the vertical direction on the main surface of the widthwise end of the glass plate, which is held in a vertical position. Then, the area around the scribe line is curved to apply bending stress and cut the glass ribbon along the scribe line. This scribe cutting is performed separately on one end and the other end of the glass plate in the widthwise direction. As a result, a glass plate without edges on both ends in the widthwise direction is obtained.

[0008] Next, in the glass plate manufacturing method, as disclosed in Patent Document 3, a process (packaging process) is carried out in which the glass plates from which the edges have been removed are loaded onto a pallet using a conveying device and packaged.

[0009] The conveying device has a holding section consisting of a chuck or the like that holds the top of the glass plate. The glass plate is transported in a suspended state in an upright position, with its top held by the holding section. This packaging process forms a glass plate package in which multiple glass plates are packed vertically on a pallet. The glass plate package is then transported to the next process or stored until the next process is carried out. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2017-202958 [Patent Document 2] Japanese Patent Publication No. 2017-226549 [Patent Document 3] Japanese Patent Publication No. 2020-75752 [Overview of the project] [Problems that the invention aims to solve]

[0011] In the conventional glass film manufacturing method described above, the glass plates packaged in the glass plate packaging have scribe marks remaining on both ends in the width direction due to the formation of scribe lines.

[0012] In the packaging process, when the top of the glass plate is held by the holding part of the conveying device, the glass plate vibrates during transport, causing bending stress to act on it. Therefore, in conventional glass plate manufacturing methods, this bending stress acting during transport could cause cracks to occur at the scribe marks remaining on both ends of the glass plate in the width direction.

[0013] This invention has been made in view of the above circumstances, and its technical objective is to prevent damage to glass plates that are stacked vertically on a pallet. [Means for solving the problem]

[0014] The present invention is for solving the above problems and is a method for manufacturing a glass plate comprising a cutting step of removing the widthwise end of the glass plate while the glass plate is supported in a vertical position, wherein the cutting step includes a scribing step of forming a scribe line including a median crack along the vertical direction in the glass plate using a scribe tool, and a breaking step of applying bending stress to the glass plate on which the scribe line has been formed to break it, wherein the scribe line is formed in the scribing step such that the maximum depth of the median crack in the middle of the scribe line is shallower than the maximum depth of the median crack in the lower part of the scribe line.

[0015] With this configuration, the maximum depth of the median crack in the middle of the scribe line can be made shallower, thereby reducing the maximum depth of the median crack in the scribe mark in the middle of the end face in the width direction of the glass plate after the cutting process. This prevents cracks from occurring in the middle of the end face of the glass plate even if bending stress due to the shaking of the glass plate acts on it during vertical transport. This makes it possible to prevent damage to glass plates that are stacked vertically on a pallet.

[0016] In addition, by making the maximum depth of the median crack at the bottom of the scribe line greater than the maximum depth of the median crack in the middle of the scribe line, it is possible to prevent cutting defects at the bottom of the scribe line during the folding process and to cut the glass plate with high precision.

[0017] In the method for manufacturing a glass plate according to the present invention, the maximum depth of the median crack in the middle portion of the scribe line may be shallower than the maximum depth of the median crack in the upper portion of the scribe line.

[0018] With this configuration, by making the maximum depth of the median crack at the top of the scribe line deeper than the maximum depth of the median crack in the middle section, the crack can be stably propagated from the top of the scribe line downwards towards the middle and bottom sections during the folding process. This makes it possible to prevent the occurrence of cutting defects during the cutting process. Furthermore, even if the glass plate is warped, it is possible to fold the glass plate without causing cutting defects.

[0019] In the method for manufacturing a glass plate according to the present invention, the maximum depth of the median crack in the upper part of the scribe line may be shallower than the maximum depth of the median crack in the middle part of the scribe line.

[0020] According to such a configuration, by reducing the maximum depth of the median crack at the upper part of the scribe line, the maximum depth of the median crack of the scribe mark remaining at the upper part of the end face in the width direction of the glass plate formed by the breaking process can be reduced. Thereby, when manufacturing the glass plate package, even when the upper part of the glass plate is held by holding means such as a chuck, breakage of the upper part of the glass plate due to impact during conveyance or the like can be prevented.

[0021] The present invention is for solving the above problems, and is a glass plate package including a rectangular glass plate and a pallet on which the glass plates are stacked in a vertical posture. The glass plate has end faces extending in the vertical direction at the ends in the width direction. The end faces are fracture surfaces having scribe marks including median cracks. The maximum depth of the median crack in the middle part of the end face is shallower than the maximum depth of the median crack in the lower part of the end face.

[0022] According to such a configuration, by reducing the maximum depth of the median crack of the scribe mark in the middle part of the end face extending in the vertical direction in the glass plate, even if bending stress due to the shaking of the glass plate acts on the glass plate during conveyance in the vertical posture of the glass plate, it is possible to prevent cracks from occurring in the middle part of the end face of the glass plate. Thereby, breakage of the glass plate stacked on the pallet in a vertical posture can be prevented.

[0023] In the glass plate package according to the present invention, the maximum depth of the median crack in the middle part of the end face may be shallower than the maximum depth of the median crack in the upper part of the end face.

[0024] According to such a configuration, even when bending stress due to the shaking of the glass plate acts on the middle part of the end face in the width direction of the glass plate when the glass plate is conveyed in a vertical posture, generation of cracks in the middle part can be more effectively prevented.

[0025] In the glass plate packaging according to the present invention, the maximum depth of the median crack in the upper part of the end face may be shallower than the maximum depth of the median crack in the middle part of the end face.

[0026] With this configuration, even when the upper part of the glass plate is held by a retaining means such as a chuck during the manufacture of the glass plate packaging, it is possible to prevent damage to the upper part of the glass plate due to impacts during transport.

[0027] The present invention is intended to solve the above problems and is a rectangular glass plate having an end face extending in the plate drawing direction, wherein the end face is a fold surface having a scribe mark including a median crack, and the maximum depth of the median crack in the middle portion of the end face in the plate drawing direction is shallower than the maximum depth of the median crack at one end of the end face in the plate drawing direction.

[0028] With this configuration, even if bending stress is applied to the middle of the end face due to the shaking of the glass plate when it is transported in a vertical position, it is possible to prevent cracking in this middle section. This makes it possible to prevent damage to glass plates that are stacked vertically on a pallet. [Effects of the Invention]

[0029] According to the present invention, it is possible to prevent damage to glass plates that are stacked vertically on a pallet. [Brief explanation of the drawing]

[0030] [Figure 1] This is a flowchart showing a method for manufacturing glass plates. [Figure 2] This is a perspective view showing a part of the manufacturing method for glass plates. [Figure 3] This is a side view showing the second cutting step in the glass plate manufacturing method. [Figure 4] This is a perspective view showing an example of a glass plate. [Figure 5]Figure 4 is a graph showing the relationship between the position of the scribe lines on the glass plate and the depth of the median crack. [Figure 6] This is a perspective view showing another example of a glass plate. [Figure 7] Figure 6 is a graph showing the relationship between the position of the scribe lines on the glass plate and the depth of the median crack. [Figure 8] This is a perspective view showing the packaging process in the manufacturing method of glass plates. [Figure 9] This is a perspective view of a glass plate packaging. [Modes for carrying out the invention]

[0031] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Figures 1 to 9 show one embodiment of the glass plate, the method for manufacturing the same, and the glass plate packaging according to the present invention.

[0032] As shown in Figure 1, the method for manufacturing a glass plate according to the present invention mainly comprises a molding step S1, a first cutting step S2, a second cutting step S3, and a packaging step S4.

[0033] The molding process S1 is a process for forming a glass ribbon GR from molten glass GM. As shown in Figure 2, in the molding process S1, molten glass GM is supplied to the overflow groove 1a at the top of the wedge-shaped molded body 1 and allowed to overflow. The overflowing molten glass GM is then allowed to flow down along the sides of the molded body 1 and then fused together at the lower end of the molded body 1.

[0034] This process forms a plate-shaped glass ribbon GR. The formed glass ribbon GR is then held from both sides by multiple pairs of rollers (not shown) arranged in upper and lower tiers and pulled downwards. A cooling roller pair is positioned at the top of the multiple pairs of rollers arranged in upper and lower tiers. In this embodiment, the pulling direction Y in the forming process S1 is set to be aligned with the vertical direction.

[0035] The formed glass ribbon GR has a first main surface 2 and a second main surface 3. In this embodiment, a glass ribbon GR is provided in which the first main surface 2 is a non-guaranteed surface and the second main surface 3 is a guaranteed surface. Here, the guaranteed surface is the surface on which elements, etc., are formed in the glass plate finally obtained from the glass ribbon GR, and its surface properties are guaranteed, whereas the non-guaranteed surface is a surface on which the surface properties do not need to be guaranteed to the same extent as the guaranteed surface.

[0036] At both ends (Ga) of the glass ribbon GR in the width direction, there are tabs that are thicker than those at the center in the width direction. The thickness of the center of the glass ribbon GR in the width direction is 1000 μm or less, preferably 700 μm or less, and its lower limit is, for example, 50 μm or more.

[0037] The first cutting step S2 is a step in which a first glass plate G1 is cut out from the glass ribbon GR formed in the molding step S1 by scribe cutting along the width direction X. The first cutting step S2 includes a scribe step in which a scribe line SL1 is formed on the glass ribbon GR with a scribe tool, and a folding step in which bending stress is applied to the glass ribbon GR on which the scribe line SL1 has been formed, causing it to break.

[0038] In the scribing process, the scribe wheel 4, acting as a scribe tool, is pressed against the surface of the glass ribbon GR and moves from the position indicated by the dashed line to the position indicated by the solid line, thereby forming a scribe line SL1 along the width direction X on the first main surface 2 of the glass ribbon GR.

[0039] At this time, the region where the scribe line SL1 is formed is supported from the second main surface 3 side by a support member (not shown). A gripping mechanism 5 is located below the scribe wheel 4 and the support member, but the gripping mechanism 5 is not activated during the scribe process.

[0040] After the scribe line SL1 is formed, the scribe wheel 4 and support member retract to the retracted position. In the illustrated example, the scribe line SL1 does not reach both ends of the glass ribbon GR in the width direction, but it may reach both ends.

[0041] Next, in the folding process, with the folding member 6 supporting the area where the scribe line SL1 is formed from the second main surface 3 side, the gripping mechanism 5, which grips the lower end of the glass ribbon GR, rotates in the direction of arrow a, thereby applying bending stress to the scribe line SL1. This allows the glass ribbon GR to be folded along the scribe line SL1. This scribe cutting by folding cuts out a rectangular first glass plate G1 having tabs on both ends Ga in the width direction.

[0042] The first glass plate G1 is transported by the transport device 7 to a position where the second cutting process S3 can be performed (transport process). The transport device 7 is configured to transport the first glass plate G1 while holding it in a vertical position. The transport device 7 has a holding part 7a that holds the upper part of the first glass plate G1.

[0043] The holding part 7a is composed of, for example, a chuck that grips the first glass plate G1, but is not limited to this, and may be composed of holding means such as a suction pad. The holding part 7a is configured to be movable in a predetermined direction by a guide rail or the like. The holding part 7a holds only the upper part of the first glass plate G1 and transports the first glass plate G1 in a suspended state in a vertical position.

[0044] The second cutting step S3 is a step in which the widthwise end Ga of the first glass plate G1 is cut. That is, in the second cutting step S3, with the first glass plate G1 supported in a vertical position by the transport device 7, the widthwise end Ga of the first glass plate G2 is cut out by removing the ends Ga along the vertical direction.

[0045] The second cutting step S3 includes a scribing step of forming a scribe line SL2 containing a median crack MC in the first glass plate G1 using a scribe tool, and a folding step of applying bending stress to the first glass plate G1 on which the scribe line SL2 has been formed, thereby breaking it.

[0046] In the scribing process, a portion of the second main surface 3 of the first glass plate G1 is supported by two support members (not shown). In this state, two scribe wheels 8, acting as scribe tools, form scribe lines SL2 at predetermined positions on both ends Ga in the width direction of the first glass plate G1 (slightly inward in the width direction from the edges).

[0047] The two scribe wheels 8 move from the position indicated by the dashed line to the position indicated by the solid line, while pressing predetermined positions on both ends Ga in the width direction of the first main surface 2 of the first glass plate G1. As a result, two scribe lines SL2 are formed along the vertical direction on the first main surface 2 of the first glass plate G1.

[0048] The scribe line SL2 is configured to be a straight line along the vertical direction, corresponding to the plate drawing direction Y. The scribe line SL2 has a starting end SL2a and an ending end SL2b. In this embodiment, the starting end SL2a of the scribe line SL2 is located below the upper end of the first glass plate G1, but it is not limited to this, and the starting end SL2a of the scribe line SL2 may be set at the upper end of the first glass plate G1. The distance from the upper end surface of the first glass plate G1 to the starting end SL2a of the scribe line SL2 is, for example, 10 mm to 300 mm.

[0049] The terminal end SL2b of the scribe line SL2 is located above the lower end of the first glass plate G1, but is not limited to this; the terminal end SL2b of the scribe line SL2 may also be set at the lower end of the first glass plate G1. The distance from the lower end surface of the first glass plate G1 to the terminal end SL2a of the scribe line SL2 is, for example, 10 mm to 300 mm. In this case, the two scribe lines SL2 may be formed simultaneously or separately over time. Also, the starting end SL2a and ending end SL2b of the scribe line SL2 may be in opposite positions vertically.

[0050] Hereinafter, the upper part of the scribe line SL2 is denoted by the symbol UP1, with the upper end (starting end SL2a) of the scribe line SL2 as the starting point and the end point being 25% below the upper surface of the first glass plate G1. The lower part of the scribe line SL2 is denoted by the symbol BP1, with the lower end (ending end SL2b) of the scribe line SL2 as the starting point and the end point being 25% above the lower surface of the first glass plate G1. The portion between the upper UP1 and lower BP1 of the scribe line SL2 is called the middle part of the scribe line SL2 and is denoted by the symbol MP1. Note that the position 25% below the upper surface means the position located a distance A below the upper surface, where A is the length obtained by multiplying the length from the upper surface to the lower surface of the first glass plate G1 by 0.25. Similarly, the position 25% above the lower surface means the position located a distance A above the lower surface.

[0051] As shown in Figure 3, the scribe line SL2 forms a plastic deformation layer PDL and a median crack MC in the first glass plate G1. The plastic deformation layer PDL is formed when the first main surface 2 of the first glass plate G1 is pressed by the scribe wheel 8. The median crack MC is formed integrally with a first crack MCa called a rib mark and a second crack MCb formed at a deeper position than the first crack MCa. In this embodiment, the depth (D1 + D2) obtained by adding the depth D1 of the first crack MCa and the depth D1 of the second crack MCb is called the "depth of the median crack".

[0052] In the scribing process according to this embodiment, by adjusting the pressing force of the scribe wheel 8 against the first main surface 2 of the first glass plate G1, the scribe line SL2 is formed such that the depth of the median crack MC differs along its longitudinal direction (plate drawing direction Y).

[0053] As shown in Figure 2, in the folding process, the first glass plate G1 is folded along two scribe lines SL2 while the second main surface 3 side of the first glass plate G1 is supported by two support members 9. In this case, the support members 9 support the portion of the first glass plate G1 slightly towards the center in the width direction from the two scribe lines SL2. In this state, the first glass plate G1 is folded by pushing both ends Ga in the width direction from the first main surface 2 side toward the back side (second main surface 3 side) with a pressing member (not shown).

[0054] By scribing at these two points, the widthwise ends Ga of the first glass plate G1, including the edges, are removed. This yields a second glass plate G2 without edges. In this case, the scribing at the two points may be performed simultaneously or separately at different times. The resulting second glass plate G2 has a widthwise dimension of, for example, 1500 mm or more, preferably 2000 mm or more, and more preferably 3000 mm or more. On the other hand, the upper limit can be, for example, 4000 mm or less. The dimension of the second glass plate G2 in the cutting direction is, for example, 1300 mm or more, preferably 2000 mm or more, and more preferably 2500 mm or more. On the other hand, the upper limit can be, for example, 3600 mm or less.

[0055] The second glass plate G2 has an upper end surface ESU, a lower end surface ESB, and a pair of side end surfaces ESS newly formed by removing Ga from both widthwise ends of the first glass plate G1. The upper end surface ESU and lower end surface ESB of the second glass plate G2 are elongated surfaces that extend horizontally in the second glass plate G2 when it is in a vertical position. The side end surface ESS of the second glass plate G2 is an elongated folded surface that extends vertically in the direction corresponding to the plate drawing direction Y. Scrib marks, including median cracks MC formed by the second cutting process S3, remain on this side end surface ESS.

[0056] Furthermore, the drawing direction Y of the second glass plate G2 can be observed, for example, by cutting a sample of a predetermined size from the second glass plate G2, irradiating it with light from a light source (e.g., a xenon light) while adjusting the angle of the sample in a dark room, and projecting the transmitted light onto a screen, thereby observing it as a striped pattern. Therefore, even in the state of the second glass plate G2 after the second cutting process S3, the side end face ESS extending along the drawing direction Y during molding can be identified.

[0057] Hereinafter, the portion of the side edge ESS extending 25% downward from the upper end surface ESU of the second glass plate G2 (25% of the length from the upper end surface ESU to the lower end surface ESB) will be referred to as the upper part (end) of the side edge ESS and will be denoted by the symbol UP2. The portion of the side edge ESS extending 25% upward from the lower end surface ESB of the second glass plate G2 will be referred to as the lower part (end) of the side edge ESS and will be denoted by the symbol BP2. The portion of the side edge ESS between the upper part UP2 and the lower part BP2 will be referred to as the middle part of the side edge ESS and will be denoted by the symbol MP2.

[0058] The depth of the median crack MC in the scribe line SL2 formed in the first glass plate G1 by the second cutting step S3 corresponds to the depth of the median crack in the scribe mark remaining on the side edge surface ESS of the second glass plate G2. Therefore, by measuring the depth of the median crack in the scribe mark remaining on the side edge surface ESS of the second glass plate G2 (depth from the first main surface 2), the depth of the median crack MC related to the scribe line SL2 formed by the second cutting step S3 can be determined. The depth of the median crack is measured, for example, by observing the side edge surface ESS of the second glass plate G2 with an electron microscope. In the glass plate packaging and glass plate of the present invention, the maximum depth of the median cracks in the upper, middle, and lower parts shall be determined from the depth distribution obtained by measuring the depth of the median crack at 100 mm intervals along the plate drawing direction. This measurement of the median crack depth shall be performed by taking a sample including the side edge surface ESS of the second glass plate G2 and observing the side edge surface ESS with an electron microscope using that sample.

[0059] The following describes the characteristics of the median cracks in the scribe marks remaining on the side edge face ESS of the second glass plate G2, and their relationship to the median crack MC of the scribe line SL2, with reference to Figures 4 to 7.

[0060] Figures 4 to 7 illustrate second glass plates G2 formed by scribe lines SL2 with different median crack MC characteristics. In these examples, Figures 4 and 6 show the median crack MC of the scribe mark SM remaining on the side edge face ESS of the second glass plate G2.

[0061] In Figures 4 and 6, the upper end of the scribe mark SMa corresponds to the starting end SL2a of the scribe line SL2. The lower end of the scribe mark SMb corresponds to the ending end SL2b of the scribe line SL2.

[0062] The upper part of the scribe mark SM corresponds to the upper part of the scribe line SL2, so the same symbol UP1 is used. The lower part of the scribe mark SM corresponds to the lower part of the scribe line SL2, so the same symbol BP1 is used. The middle part of the scribe mark SM corresponds to the middle part of the scribe line SL2, so the same symbol MP1 is used. The upper part UP1 of the scribe mark SM is included in the upper part UP2 of the side end face ESS of the second glass plate G2. The lower part BP1 of the scribe mark SM is included in the lower part BP2 of the side end face ESS, and the middle part MP1 of the scribe mark SM is included in the middle part MP2 of the side end face ESS.

[0063] Figure 5 is a graph showing the relationship between the position of the scribe line SL2 in the drawing direction Y for forming the second glass plate G2 as illustrated in Figure 4, and the depth of the median crack MC. Figure 7 is a graph showing the relationship between the position of the scribe line SL2 in the drawing direction Y for forming the second glass plate G2 as illustrated in Figure 6, and the depth of the median crack MC. The position of the scribe line SL2 shown in Figures 5 and 7 corresponds to the position of the scribe mark SM in the drawing direction Y on the side edge face ESS of the second glass plate G2.

[0064] As shown in Figure 4, the depth of the median crack MC (depth from the first main surface 2) of the scribe mark SM remaining on the side end surface ESS of the second glass plate G2 in the first embodiment is maximum at the upper end SMa and gradually decreases as it moves downward from the upper end SMa. The depth of the median crack MC is minimum at the middle part P of the middle part MP2 of the side end surface ESS. The position P where the depth of the median crack MC is minimum is preferably set to, for example, an intermediate position in the vertical direction of the median crack MC, that is, a position where the distance from the upper end SMa of the scribe mark SM is equal to the distance from the lower end SMb. Furthermore, the depth of the median crack MC gradually increases as it moves downward from this minimum position P. The depth of the median crack MC is maximum at the lower end SMb of the scribe mark SM.

[0065] Therefore, the maximum depth of the median crack MC in the middle section MP2 of the side end face ESS is shallower than the maximum depth of the median crack MC in the lower section BP2 of the side end face ESS (one end of the side end face ESS in the plate drawing direction Y). Also, the maximum depth of the median crack MC in the middle section MP2 of the side end face ESS is shallower than the maximum depth of the median crack MC in the upper section UP2 of the side end face ESS (the other end of the side end face ESS in the plate drawing direction Y).

[0066] In other words, as shown in Figure 5, the depth of the median crack MC of the scribe line SL2 formed in the first glass plate G1 during the second cutting process S3 is deepest at the beginning end SL2a and the end end SL2b of the scribe line SL2 (D MAX ), the shallowest (D) in the middle part P of the middle part MP1 MIN ).

[0067] In other words, the scribe line SL2 is formed such that the maximum depth of the median crack MC in its intermediate section MP1 (intermediate section P) is shallower than the maximum depth of the median crack MC in its lower section BP1. Furthermore, the scribe line SL2 is formed such that the maximum depth of the median crack MC in its intermediate section MP1 (intermediate section P) is shallower than the maximum depth of the median crack MC in its upper section UP1.

[0068] In the second glass plate G2 of the second embodiment shown in Figure 6, the depth of the median crack MC in the scribe mark SM remaining on the side end face ESS gradually increases from the upper end SMa of the scribe mark SM located on the upper part UP2 of the side end face ESS towards the lower end SMb. The depth of the median crack MC is minimum at the upper end SMa and maximum at the lower end SMb.

[0069] Therefore, the maximum depth of the median crack MC in the middle section MP2 of the side end face ESS is shallower than the maximum depth in the lower section BP2. Also, the maximum depth of the median crack MC in the upper section UP2 of the side end face ESS is shallower than the maximum depth of the median crack MC in the middle section MP2.

[0070] More specifically, as shown in Figure 7, the depth of the median crack MC of the scribe line SL2 formed in the first glass plate G1 during the second cutting step S3 is shallowest at the starting end SL2a (D MIN ), the deepest at the terminal SL2b (D MAX ). Also, the scribe line SL2 is the depth of the median crack MC in the intermediate section MP1 (the maximum depth in the intermediate section MP1 or the depth D in the intermediate section P). P ) is formed such that the depth of the median crack MC in the lower BP1 (the minimum depth in the lower BP1) is shallower. Also, the scribe line SL2 is formed such that the depth of the median crack MC in the upper UP1 (the maximum depth in the upper UP1) is shallower than the depth of the median crack MC in the middle MP1 (the minimum depth in the middle MP1 or the depth D in the intermediate P). PIt is formed to be shallower than ).

[0071] In the second glass plate G2 of the first and second embodiments, when the thickness is 200 μm or more, the maximum depth of the median crack MC in the intermediate MP2 of the side end face ESS can be, for example, 90 μm or less, and from the viewpoint of preventing breakage, it is preferable that it be 80 μm or less. On the other hand, from the viewpoint of stabilizing the folding, the minimum depth of the median crack MC in the intermediate MP2 is preferably 30 μm or more, and more preferably 50 μm or more.

[0072] In the second glass plate G2 of the first and second embodiments, when the thickness is 200 μm or more, the difference (d1-d2) between the maximum depth d1 of the median crack MC in the lower part BP1 of the scribe line SL2 and the maximum depth d2 of the median crack MC in the middle part MP2 is preferably 10 μm or more, and more preferably 20 μm or more, in order to prevent the occurrence of cutting defects in the lower part of the second glass plate G2 in the second cutting step S3. On the other hand, the upper limit of the difference (d1-d2) can be, for example, 80 μm or less.

[0073] In the second glass plate G2 of the first embodiment, the maximum depth of the median crack MC in the upper part UP1 may be the same as the maximum depth of the median crack MC in the middle part MP2, or it may be deeper than the maximum depth of the median crack MC in the middle part MP2.

[0074] In the second glass plate G2 of the second embodiment, the maximum depth of the median crack MC in the upper part UP1 is made shallower than the maximum depth of the median crack MC in the middle part MP1. From the viewpoint of preventing damage to the glass plate when the upper part of the glass plate is held by a holding means such as a chuck, the difference (d2-d3) between the maximum depth d2 of the median crack MC in the middle part MP2 and the maximum depth d3 of the median crack MC in the upper part UP1 is preferably 10 μm or more, and more preferably 20 μm or more. On the other hand, the minimum depth of the median crack MC in the upper part UP1 can be 20 μm or more.

[0075] The packaging process S4 is a process for manufacturing a glass plate package by stacking multiple second glass plates G2 onto a pallet. After the completion of the second cutting process S3, the second glass plates G2 are transported to the pallet by the conveying device 7.

[0076] As shown in Figure 8, in the packaging process S4, the second glass plates G2 cut in the second cutting process S3 are suspended and supported in a vertical position and stacked alternately on the pallet 11 with the protective sheet 10. The protective sheet 10 is a foamed resin sheet, but it may also be a non-foamed resin sheet or laminated paper.

[0077] The second glass plate G2, which is to be loaded onto the pallet 11, is oriented along the vertical plane. In contrast, the back support surface 12a of the back support portion 12 of the pallet 11 is an inclined surface that slopes towards the rear as it moves upward. The angle of inclination of the back support surface 12a with respect to the horizontal plane is, for example, 60° to 85°. Therefore, the glass plate laminate 13, which is composed of the second glass plate G2 and the protective sheet 10 already loaded onto the pallet 11, is in a vertical orientation, but is inclined in accordance with the back support surface 12a.

[0078] The second glass plate G2 is suspended vertically by the conveying device 7 and then loaded onto the pallet 11. In this case, the second glass plate G2 is loaded onto the pallet 11 such that the second main surface 3, which serves as the guarantee surface, faces the back support surface 12a of the pallet 11.

[0079] As shown in Figure 9, the glass plate packaging GPB manufactured by carrying out the packaging process S4 comprises a glass plate laminate 13 in which a rectangular second glass plate G2 and a rectangular protective sheet 10 are alternately stacked in a vertical position (more precisely, in the inclined position described above), and a pallet 11 on which the glass plate laminate 13 is stacked.

[0080] Furthermore, the glass plate packaging GPB also includes packaging materials such as cable ties Ba to prevent the glass plate laminate 13 from collapsing. Preferably, the cable ties Ba are provided so as to be located within the range of the intermediate portion MP2 on the side end face ESS of the second glass plate G2 included in the glass plate laminate 13.

[0081] The pallet 11 includes a rear support portion 12 having the inclined back support surface 12a described above, as well as a bottom support portion 14 that supports the bottom surface of the glass plate laminate 13. The bottom receiving surface 14a of the bottom support portion 14 is an inclined surface that slopes upward as it moves towards the front.

[0082] According to the embodiment described above, in the second cutting step S3, by making the maximum depth of the median crack MC in the middle part MP1 of the scribe line SL2 formed on the first glass plate G1 shallower than the maximum depth of the median crack MC in the lower part BP1, the depth of the median crack MC in the scribe mark SM in the middle part MP2 of the side end face ESS of the cut second glass plate G2 can be made as shallow as possible.

[0083] In the packaging process S4, when the second glass plate G2 is transported by the conveying device 7, the second glass plate G2 experiences vibration. This vibration causes bending stress to act on the intermediate MP2 of the side end face ESS, potentially causing cracks in the intermediate MP2. In particular, the deeper the maximum depth of the median crack MC in the scribe mark SM, the more likely the intermediate MP2 of the side end face ESS is to break. In this embodiment, by making the maximum depth of the median crack MC in the intermediate MP2 of the side end face ESS of the second glass plate G2 shallower, it is possible to prevent cracking of the intermediate MP2 of the side end face ESS during transport. This makes it possible to prevent damage to the second glass plate G2 when it is loaded vertically on the pallet 11.

[0084] Furthermore, by making the maximum depth of the median crack MC in the lower part BP1 of the scribe line SL2 deeper than the maximum depth of the median crack MC in the middle part MP1 of the scribe line SL2, it is possible to prevent the occurrence of cutting defects in the lower part of the second glass plate G2 in the second cutting process S3.

[0085] In other words, if the maximum depth of the median crack MC in the lower BP1 of the scribe line SL2 is shallow, the crack propagation due to the application of bending stress in the second cutting process S3 may become unstable in this lower BP1.

[0086] In this case, the lower part BP2 of the end face of the second glass plate G2 is prone to developing protrusions that extend outward in the width direction X, or concave chips that extend inward in the width direction X. When such cutting defects occur, the lower part of the second glass plate G2 is prone to damage when loading onto the pallet 11 or when transporting the glass plate packaging GPB. In this embodiment, by making the maximum depth of the median crack MC in the lower part BP1 of the scribe line SL2 deeper than the maximum depth of the median crack MC in the middle part MP1 of the scribe line SL2, it is possible to prevent cutting defects and prevent damage to the second glass plate G2 in the glass plate packaging GPB.

[0087] Furthermore, in the glass plate packaging GPB, by providing a cable tie Ba within the range of the intermediate portion MP2 on the side end face ESS of the second glass plate G2 included in the glass plate laminate 13, it is possible to avoid the tightening force of the cable tie Ba acting on the upper UP2 and lower BP2 of the second glass plate G2. This prevents damage to the upper UP2 or lower BP2 of the second glass plate G2 during transport of the glass plate packaging GPB.

[0088] Furthermore, the present invention is not limited to the configuration of the above embodiments, nor is it limited to the effects described above. The present invention can be modified in various ways without departing from the spirit of the invention.

[0089] In the above embodiment, an example was shown of measuring the depth of the median crack MC in the scribe mark SM on the folded surface (side end surface ESS) of the second glass plate G2, but the present invention is not limited to this configuration. For example, in the second cutting step S3, the depth of the median crack MC in the scribe line SL2 may be measured by measuring the depth of the median crack in the scribe mark remaining on the folded surface of the widthwise end Ga cut off from the first glass plate G1. [Explanation of Symbols]

[0090] 8. Scribe Wheel (Scribe Tool) 11 Palettes Lower part of the BP1 scribe line Lower part of the side end face of the second glass plate BP2 Side edge of the second glass plate of ESS G1 First Glass Plate G2 Second Glass Plate Ga The end of the first glass plate in the width direction GPB glass sheet packaging MC Median Crack MP1 scribe line midway MP2 Intermediate part of the side end face of the second glass plate S3 Second cutting process SL2 scribe line SM scribe marks UP1 Top of the scribe line UP2 Upper part of the side end surface of the second glass plate X Width direction Y-shaped board cutting direction

Claims

1. A method for manufacturing a glass plate, comprising a cutting step of removing the widthwise end of the glass plate while the glass plate is supported in a vertical position, The cutting process includes a scribing step of forming a scribe line containing a median crack along the vertical direction in the glass plate using a scribe tool, and a breaking step of applying bending stress to the glass plate on which the scribe line has been formed to break it. A method for manufacturing a glass plate, characterized in that, in the scribing step, the scribe line is formed such that the maximum depth of the median crack in the middle of the scribe line is shallower than the maximum depth of the median crack in the lower part of the scribe line.

2. The method for manufacturing a glass plate according to claim 1, wherein the maximum depth of the median crack in the middle portion of the scribe line is shallower than the maximum depth of the median crack in the upper part of the scribe line.

3. The method for manufacturing a glass plate according to claim 1, wherein the maximum depth of the median crack in the upper part of the scribe line is shallower than the maximum depth of the median crack in the middle part of the scribe line.

4. A glass plate packaging comprising a rectangular glass plate and a pallet on which the glass plates are stacked in a vertical position, The glass plate has an end face extending in the vertical direction at its widthwise end, The end face is a scribing surface having scribe marks including a median crack. A glass plate packaging body characterized in that the maximum depth of the median crack in the middle portion of the end face is shallower than the maximum depth of the median crack in the lower part of the end face.

5. The glass plate packaging body according to claim 4, wherein the maximum depth of the median crack in the intermediate portion of the end face is shallower than the maximum depth of the median crack in the upper part of the end face.

6. The glass plate packaging according to claim 4, wherein the maximum depth of the median crack at the upper part of the end face is shallower than the maximum depth of the median crack at the intermediate part of the end face.

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