Manufacturing method for glass articles

Abstract

To provide a method for manufacturing a glass article, capable of achieving both the prevention of cracks and the suppression of warp in a thin glass ribbon when slowly cooling the glass ribbon in a slow cooling furnace while conveying the glass ribbon below.SOLUTION: A method for manufacturing a glass article comprises the molding step P1 of molding a glass ribbon 5 and the slow cooling step P2 of slowly cooling the glass ribbon 5 in a slow cooling furnace 8 while conveying the glass ribbon below. First and second conveying rollers CR1 and CR2 for conveying the glass ribbon 5 are arranged at a distance L in the vertical direction in the slow cooling furnace 8; and in the slow cooling step P2, the glass ribbon 5 is conveyed while bringing the first conveying roller CR1 into contact with one surface S1 the glass ribbon 5 and bringing the second conveying roller CR2 into contact with the other surface S2 of the glass ribbon 5.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing a glass article, comprising: a forming step of forming a glass ribbon; and a slow cooling step of slowly cooling the glass ribbon in a slow cooling furnace while conveying the glass ribbon downward. BACKGROUND ART

[0002] As a method for manufacturing a glass sheet, which is one type of glass article, a downdraw method represented by the overflow downdraw method is known. In this method, after performing a forming step of forming a glass ribbon that is a base of the glass sheet, a slow cooling step of slowly cooling the glass ribbon in a slow cooling furnace while conveying the glass ribbon downward is performed. The internal strain of the glass ribbon is removed by performing this slow cooling step. Thereafter, the glass sheet is manufactured through steps such as a cutting step of cutting the glass ribbon into pieces each having a predetermined length.

[0003] One example of a form of conveying a glass ribbon in the slow cooling step includes conveying the glass ribbon while sandwiching it by pairs of rollers arranged in a plurality of upper and lower stages in the slow cooling furnace. Each pair of rollers consists of a roller contacting one surface of the glass ribbon and a roller contacting the other surface of the glass ribbon, and the two rollers can sandwich the glass ribbon in the thickness direction. The pairs of rollers are arranged on one side and the other side in the width direction of the glass ribbon, respectively, at each of the plurality of upper and lower stages. Accordingly, the pairs of rollers on the one side and the other side sandwich both widthwise end portions of the glass ribbon, respectively.

[0004] In recent years, the thinning of glass sheets has been promoted. Along with this, the thinning of glass ribbons formed by the downdraw method is also progressing. However, when a thin glass ribbon (for example, having a thickness of 300 µm or less) is subjected to the slow cooling step under the above-described conveyance form, the glass ribbon sometimes breaks. This is because, as the glass ribbon is sandwiched between the pair of rollers, micro scratches such as microcracks that become starting points of breaking are formed on the glass ribbon.

[0005] As a countermeasure against the cracking of the glass ribbon as described above, it is conceivable to transport the glass ribbon without pinching it with a pair of rollers inside the annealing furnace (annealer 5 in the same document), as disclosed in Patent Document 1. In this configuration, the pair of rollers (the two rollers constituting the roller pair) placed inside the annealing furnace guide the glass ribbon downwards while maintaining a gap between itself and the glass ribbon. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-87004 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The transport method disclosed in Patent Document 1 can prevent glass ribbon breakage, but it has the problem that glass ribbon tends to warp (warp along the width direction). This is because the glass ribbon is not held between roller pairs at both ends in the width direction, causing it to slowly cool and shrink in a relaxed state. For these reasons, there has been a need to establish a technology that can not only prevent the breakage of thin glass ribbons but also suppress warping.

[0008] In light of the circumstances described above, the technical challenge to be addressed is to prevent cracking and suppress warping of glass ribbons when manufacturing glass articles, while slowly cooling thin glass ribbons in an annealing furnace while conveying them downwards. [Means for solving the problem]

[0009] A first method for manufacturing a glass article to solve the above problems comprises a molding step of forming a glass ribbon and an annealing step of slowly cooling the glass ribbon in an annealing furnace while conveying it downwards, wherein a first conveying roller and a second conveying roller for conveying the glass ribbon are arranged in the annealing furnace at a distance from each other in the vertical direction, and in the annealing step, the glass ribbon is conveyed while the first conveying roller is in contact with one side of the glass ribbon and the second conveying roller is in contact with the other side of the glass ribbon.

[0010] In the first method for manufacturing glass articles, the first and second conveyor rollers each contact the glass ribbon, allowing a load in the thickness direction to be applied to the glass ribbon from each of the two conveyor rollers, thereby making the glass ribbon taut. As a result, warping of the glass ribbon can be suppressed. Furthermore, in this manufacturing method, the first and second conveyor rollers contact different surfaces of the glass ribbon, while the two conveyor rollers are spaced apart in the vertical direction. That is, the glass ribbon is not sandwiched in the thickness direction by the two conveyor rollers. As a result, cracking of the glass ribbon can be prevented. As described above, this manufacturing method can achieve both prevention of cracking and suppression of warping of thin glass ribbons.

[0011] The second method for manufacturing a glass article is the same as the first method for manufacturing a glass article described above, but with the first and second conveyor rollers arranged such that they overlap in the thickness direction of the glass ribbon when viewed from a direction parallel to the vertical direction.

[0012] In the second method for manufacturing glass articles, due to the arrangement of the two conveyor rollers, the glass ribbon is pressed in the thickness direction by each of the two conveyor rollers, resulting in a greater load on the glass ribbon from each conveyor roller. Therefore, this is advantageous in giving tension to the glass ribbon and makes it possible to further suppress the warping of the glass ribbon.

[0013] The third method for manufacturing a glass article is the same as the second method for manufacturing a glass article described above, but with L being the vertical distance (mm) from the axis of the first conveyor roller to the axis of the second conveyor roller, and D being the overlapping length (mm) of the first and second conveyor rollers in the thickness direction of the glass ribbon, the L / D value is between 30 and 200.

[0014] In the third method for manufacturing glass articles, by ensuring that the L / D value is within the above range, the distance that each of the first and second conveying rollers pushes the glass ribbon in the thickness direction can be optimized without excess or deficiency. As a result, it becomes possible to further suppress the warping of the glass ribbon.

[0015] The fourth method for manufacturing a glass article is a configuration in which, in any of the first to third methods for manufacturing a glass article described above, the first and second conveyor rollers are placed in a region of the annealing furnace at a temperature of (T-100°C) or higher, with T [°C] being the strain point of the glass ribbon.

[0016] The fourth method for manufacturing glass articles offers a favorable advantage in suppressing warping of the glass ribbon. This is because glass ribbons passing through a region of temperature above (T-100°C) in the annealing furnace are greatly affected by the degree of warping, and therefore, transporting glass ribbons in this state using the first and second transport rollers is advantageous in suppressing warping.

[0017] The fifth method for manufacturing a glass article is a method for manufacturing a glass article according to any of the first to fourth methods described above, wherein a first guide roller is positioned opposite the first conveyor roller via a glass ribbon and forming a gap between it and the glass ribbon, and a second guide roller is positioned opposite the second conveyor roller via a glass ribbon and forming a gap between it and the glass ribbon.

[0018] In the fifth method for manufacturing a glass article, it becomes possible to stably convey the glass ribbon. Specifically, the glass ribbon may swing in the thickness direction due to airflow or the like generated in the annealing lehr. Therefore, disposing the first and second guide rollers makes it possible to restrict the swing of the glass ribbon, thereby achieving stable conveyance of the glass ribbon. Each of the two guide rollers forms a gap between itself and the glass ribbon. Accordingly, the glass ribbon is not sandwiched in the thickness direction by the first conveying roller and the first guide roller, nor by the second conveying roller and the second guide roller. That is, the risk of the glass ribbon breaking due to the arrangement of the first and second guide rollers is eliminated.

[0019] A sixth method for manufacturing a glass article is the method for manufacturing a glass article according to any one of the first to fifth methods described above, wherein the glass ribbon has a thickness of 300 µm or less.

[0020] The thinner the glass ribbon is, the more easily cracking and warping occur. Therefore, when targeting a thin glass ribbon having a thickness of 300 µm or less, the effect of the present manufacturing method (which achieves both prevention of cracking of the glass ribbon and suppression of warping) becomes remarkable. [Effects of the Invention]

[0021] According to the method for manufacturing a glass article of the present disclosure, when manufacturing a glass article, it is possible to achieve both prevention of cracking of the glass ribbon and suppression of warping when the thin glass ribbon is slowly cooled in an annealing lehr while being conveyed downward. [Brief Description of the Drawings]

[0022] [Figure 1] It is a cross-sectional view schematically showing the method for manufacturing a glass article. [Figure 2] It is a cross-sectional view schematically showing the method for manufacturing a glass article. [Figure 3] It is a diagram showing the periphery of the first and second conveying rollers and the first and second guide rollers. [Figure 4] It is a cross-sectional view schematically showing a modification of the method for manufacturing a glass article. [Figure 5] It is a cross-sectional view schematically showing a modification of the method for manufacturing a glass article. MODE FOR CARRYING OUT THE INVENTION

[0023] Hereinafter, a method for manufacturing a glass article according to an embodiment will be described with reference to the attached drawings. In the present embodiment, a case where a glass plate for chemical strengthening (aluminosilicate glass) as a glass article is manufactured is taken as an example. This glass plate can be suitably used as a cover glass for various displays and solar cells. Of course, the present invention is not limited thereto, and for example, a glass plate for display (alkali-free glass) or the like may be manufactured as the glass article. This glass plate can be suitably used as a substrate for various displays. Further, a glass roll may be manufactured instead of the glass plate.

[0024] As shown in Fig. 1 and Fig. 2, when manufacturing a glass plate for chemical strengthening, first, a forming step P1, a slow cooling step P2, and a cooling step P3 are performed using a manufacturing apparatus 1 to obtain a strip-shaped glass film 2 that is a base of the glass plate for chemical strengthening. In the present embodiment, an overflow down-draw method is used to obtain the strip-shaped glass film 2. However, the present invention is not limited thereto, and a slot down-draw method, a redraw method, or the like may be used instead of the overflow down-draw method.

[0025] The forming step P1 is performed in a forming zone ZN1. In the forming step P1, a glass ribbon 5 is continuously formed from molten glass 4 by a formed body 3 for the overflow down-draw method. The formed body 3 is accommodated in a forming furnace 6, and a heating device (for example, a panel heater) (not shown) for heating the formed body 3 is installed in the forming furnace 6.

[0026] The molded body 3 has a groove 3a for allowing molten glass 4 to flow in, a pair of side portions 3b, 3b for allowing the molten glass 4 overflowing from the groove 3a to flow down on both sides, and a lower end portion 3c for fusing (merging) the molten glass 4 that has flowed down along each side portion 3b. The glass ribbon 5 is formed when the molten glass 4 fuses at the lower end portion 3c of the molded body 3.

[0027] The glass ribbon 5 has an effective portion 5a located in the center in the width direction, and non-effective portions 5b located on both sides in the width direction, with the effective portion 5a in between. The effective portion 5a is the part that will later become a product (a glass plate for chemical strengthening), while the non-effective portion 5b is the part that will not become a product and will later be discarded. Of the non-effective portions 5b that form the width direction ends of the glass ribbon 5, the part corresponding to the edge of the glass ribbon 5 has a thicker edge portion formed compared to other parts.

[0028] Immediately after molding, the glass ribbon 5 is subjected to shrinkage in the width direction using an edge roller 7 (cooling roller) positioned directly beneath the molded body 3.

[0029] The edge rollers 7 are arranged as a pair of opposing edge rollers 7,7 connected by a glass ribbon 5. This pair of edge rollers 7,7 is provided on one side and the other side in the width direction of the glass ribbon 5, respectively.

[0030] Each edge roller 7 comprises a shaft 7a extending in the width direction of the glass ribbon 5 and a roll 7b provided at the tip of the shaft 7a. The roll 7b is made of a heat-resistant material (e.g., heat-resistant steel) and contacts the non-effective portion 5b of the glass ribbon 5. A cooling medium circulates inside each edge roller 7. The glass ribbon 5 is then sandwiched in the thickness direction by the rolls 7b, 7b of the pair of edge rollers 7, 7, thereby feeding the glass ribbon 5 downward while suppressing shrinkage in the width direction.

[0031] The annealing process P2 is performed in the annealing zone ZN2. In the annealing process P2, the glass ribbon 5 descending from the molding zone ZN1 is transported downwards and slowly cooled to a temperature below the strain point. The annealing process P2 is performed using an annealing furnace 8 and annealer rollers 9 arranged in multiple vertical stages (six vertical stages in the illustrated example) within the annealing furnace 8. Note that the thinner the glass ribbon 5, the more likely it is to crack and warp. Applying the present invention significantly prevents cracking and suppresses warping, so the thickness of the glass ribbon 5 (effective portion 5a) is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. On the other hand, the lower limit of the thickness of the glass ribbon 5 (effective portion 5a) can be, for example, 20 μm or more.

[0032] The annealing furnace 8 is located below the molding furnace 6. Heating devices (e.g., panel heaters) not shown are installed on the inner surface (the surface of the wall facing the surface of the glass ribbon 5) and the outer surface (the outside of the annealing furnace 8) of the annealing furnace 8 to regulate the temperature inside the annealing furnace 8. A temperature gradient is created inside the annealing furnace 8 by these heating devices, so that the temperature of the glass ribbon 5 decreases as it descends. Here, when the strain point of the glass ribbon 5 is T [°C], all of the annealer rollers 9, which are arranged in multiple stages vertically, are located in a region where the temperature inside the annealing furnace 8 is (T-100°C) or higher. The strain point of the glass ribbon 5 is approximately 560°C as an example. The annealer rollers 9 located at the bottom may be located in a region where the temperature is below (T-100°C).

[0033] In this invention, the region in the annealing furnace 8 that is at a temperature of (T-100°C) or higher means the region where the temperature of the wall of the annealing furnace 8 facing the surface of the glass ribbon 5 is (T-100°C) or higher. The temperature of the wall of the annealing furnace 8 can be measured by a thermometer (thermocouple) placed on the wall.

[0034] In each of the multiple upper and lower tiers, the annealer rollers 9 are arranged in pairs of two annealer rollers 9,9 facing each other via the glass ribbon 5. These pairs of annealer rollers 9,9 are provided on one side and the other side in the width direction of the glass ribbon 5 in each tier. All annealer rollers 9 are positioned to face the non-effective portion 5b of the glass ribbon 5, either in contact with or not in contact with the glass ribbon 5.

[0035] Each annealer roller 9 comprises a shaft 9a extending in the width direction of the glass ribbon 5 and a roll 9b provided at the tip of the shaft 9a. The roll 9b is made of ceramic, for example. The pair of annealer rollers 9, 9 can be adjusted independently of each other in position along the thickness direction of the glass ribbon 5.

[0036] The annealer roller 9 used in this embodiment is a type of roller in which, on each of the glass ribbon 5, on one side S1 and the other side S2, the roll 9b on one side in the width direction and the roll 9b on the other side are mounted on different shafts 9a, 9a and are independent of each other. Alternatively, instead of the annealer roller 9 of the same type, a roller of the type in which the roll 9b on one side in the width direction and the roll 9b on the other side are mounted on a common shaft may be used. Or, a combination of the independent type of roller and the type of roller mounted on a common shaft may be used.

[0037] In the following explanation, to distinguish between the multiple upper and lower tiers (six tiers in total) on which the Annealer Roller 9 is placed, we will refer to them sequentially from the top tier as the first tier, second tier, ... fifth tier, sixth tier, and so on.

[0038] First, let's describe the pair of annealer rollers 9,9 positioned in the first and fourth stages. In the first and fourth stages, the rolls 9b,9b of the pair of annealer rollers 9,9 restrict the oscillation of the glass ribbon 5 along the thickness direction. The two rolls 9b,9b do not sandwich the glass ribbon 5 in the thickness direction, but rather form a gap between themselves and the glass ribbon 5. The gap between the two rolls 9b,9b is larger than the thickness of the glass ribbon 5.

[0039] Next, the pair of annealer rollers 9, 9 positioned in the second and fifth stages will be described. In the second and fifth stages, the roll 9b of the annealer roller 9 positioned on one side S1 contacts the glass ribbon 5, while the roll 9b of the annealer roller 9 positioned on the other side S2 forms a gap between itself and the glass ribbon 5. The annealer roller 9 on the one side S1 functions as a first conveyor roller CR1 that conveys the glass ribbon 5 while in contact with one side S1 of the glass ribbon 5. In contrast, the annealer roller 9 on the other side S2 functions as a first guide roller GR1 that restricts the oscillation of the glass ribbon 5. The gap between both rolls 9b, 9b is larger than the thickness of the glass ribbon 5.

[0040] Finally, the pair of annealer rollers 9,9 positioned in the third and sixth stages will be described. In the third and sixth stages, the roll 9b of the annealer roller 9 positioned on the other side S2 contacts the glass ribbon 5, while the roll 9b of the annealer roller 9 positioned on the one side S1 forms a gap between itself and the glass ribbon 5. The annealer roller 9 on the other side S2 functions as a second transport roller CR2 that transports the glass ribbon 5 while in contact with the other side S2 of the glass ribbon 5. In contrast, the annealer roller 9 on the one side S1 functions as a second guide roller GR2 that restricts the oscillation of the glass ribbon 5. The gap between both rolls 9b,9b is larger than the thickness of the glass ribbon 5.

[0041] As previously described, in each of the multiple upper and lower tiers, a pair of annealing rollers 9,9 are provided on one side and the other side in the width direction of the glass ribbon 5. The arrangement of the pair of annealing rollers 9,9 is identical between the one side and the other side.

[0042] The details of the first conveyor roller CR1, the second conveyor roller CR2, the first guide roller GR1, and the second guide roller GR2, as well as the relationships between these rollers CR1, CR2, GR1, and GR2, will be explained below based on Figure 3. Figure 3 shows the area around the second and third stages of the six-stage structure. Although not shown in the illustration, the fifth and sixth stages have a similar configuration to Figure 3.

[0043] As shown in Figure 3, the first conveyor roller CR1, which belongs to the second stage, and the second conveyor roller CR2, which belongs to the third stage, are positioned with a gap between them in the vertical direction. Specifically, the two conveyor rollers CR1 and CR2 are positioned such that the axis a1 of the first conveyor roller CR1 and the axis a2 of the second conveyor roller CR2 are separated by a distance L in the vertical direction. An example of a distance L is 200 mm to 1000 mm.

[0044] The first conveyor roller CR1 pushes the glass ribbon 5 from one side S1 to the other side S2 along the thickness direction. Specifically, the point on the periphery of the first conveyor roller CR1 (the periphery of the roll 9b) that protrudes the most towards the first guide roller GR1 (point A shown in Figure 3) is located beyond the original pass line PL of the glass ribbon 5 and towards the first guide roller GR1. Here, "original pass line PL" refers to the line extending vertically downward from the lower end 3c of the molded body 3.

[0045] Unlike the first conveyor roller CR1, the second conveyor roller CR2 pushes the glass ribbon 5 along its thickness from the other side S2 to the one side S1. Specifically, the point on the periphery of the second conveyor roller CR2 (the periphery of the roll 9b) that protrudes most towards the second guide roller GR2 (point B shown in Figure 3) is located on the second guide roller GR2 side, beyond the glass ribbon 5's original pass line PL. The distance the second conveyor roller CR2 pushes the glass ribbon 5 (the distance from the original pass line PL to point B) is the same as the distance the first conveyor roller CR1 pushes the glass ribbon 5.

[0046] As described above, both conveyor rollers CR1 and CR2 press down on the glass ribbon 5, causing the glass ribbon 5 to curve so that the other side S2 is convex near the first conveyor roller CR1, and so that the one side S1 is convex near the second conveyor roller CR2. Both conveyor rollers CR1 and CR2 may be driven rollers connected to a power source, or they may be free rollers. When both conveyor rollers CR1 and CR2 are driven rollers, it is preferable to match the peripheral speed of these rollers CR1 and CR2 to the conveying speed V1 of the glass ribbon 5. The diameters of both conveyor rollers CR1 and CR2 are, for example, 25 mm to 300 mm.

[0047] Due to the arrangement of the first conveyor roller CR1 and the second conveyor roller CR2 described above, when observed from a direction parallel to the vertical direction, both conveyor rollers CR1 and CR2 overlap in the thickness direction of the glass ribbon 5. Specifically, both conveyor rollers CR1 and CR2 overlap by a length D, and length D corresponds to the distance from point A to point B along the thickness direction. An example of length D is 1 mm to 6 mm. From the viewpoint of effectively suppressing warping by giving the glass ribbon 5 a moderate tension, the value of L / D, which is the ratio of the distance L to the length D, is preferably 30 to 200, and more preferably 40 to 150. The value of L / D corresponds to the value of tanθ in the right triangle ABC shown in Figure 3.

[0048] Herein, as a modification of this embodiment, the distance at which the glass ribbon 5 is pressed between the first conveyor roller CR1 and the second conveyor roller CR2 may be different. Furthermore, it is not essential that both conveyor rollers CR1 and CR2 press the glass ribbon 5; both conveyor rollers CR1 and CR2 may simply be in contact with the glass ribbon 5.

[0049] Due to the arrangement of the first conveyor roller CR1 and the second conveyor roller CR2 described above, the first guide roller GR1 is positioned further from the pass line PL than the second conveyor roller CR2. Similarly, the second guide roller GR2 is positioned further from the pass line PL than the first conveyor roller CR1. It should be noted that the provision of the first guide roller GR1 and the second guide roller GR2 is not mandatory and they may be removed. However, from the viewpoint of restricting the oscillation along the thickness direction of the glass ribbon 5, it is preferable to provide both guide rollers GR1 and GR2.

[0050] As shown in Figures 1 and 2, the cooling process P3 is performed in the cooling zone ZN3. In the cooling process P3, the glass ribbon 5 that has passed through the annealing zone ZN2 is cooled while being pulled downward by the support roller 10. The support roller 10 is located in the cooling chamber 11, which is positioned below the annealing furnace 8.

[0051] The support rollers 10 are arranged as a pair of opposing support rollers 10,10 connected by a glass ribbon 5. This pair of support rollers 10,10 is provided on one side and the other side in the width direction of the glass ribbon 5.

[0052] Each support roller 10 comprises a shaft 10a extending in the width direction of the glass ribbon 5 and a roll 10b provided at the tip of the shaft 10a. The roll 10b is made of rubber, for example, and contacts the non-effective portion 5b of the glass ribbon 5. The transport speed V1 (sheet pulling speed) of the glass ribbon 5 is determined by sandwiching and pulling the glass ribbon 5 in the thickness direction between the rolls 10b, 10b of the pair of support rollers 10, 10. The glass ribbon 5 that has passed through the cooling zone ZN3 is obtained as a strip-shaped glass film 2.

[0053] Once the strip-shaped glass film 2 is obtained as described above, a removal step is performed to remove the ineffective portion 5b from the strip-shaped glass film 2, a winding step is performed to wind the strip-shaped glass film 2 into a roll to form a glass roll, and a cutting step is performed to cut the unwound strip-shaped glass film 2 into predetermined lengths to produce a glass plate for chemical strengthening. Alternatively, instead of the above steps, a cutting step may be performed to obtain a glass plate by cutting the strip-shaped glass film 2 in the width direction, and a removal step is performed to remove the ineffective portion from the cut glass plate to produce a glass plate.

[0054] Herein, the following modifications can be applied to the above embodiment. In the above embodiment, the first conveyor roller CR1 is placed on the second and fifth stages of the multiple upper and lower stages, and the second conveyor roller CR2 is placed on the third and sixth stages. That is, the first conveyor roller CR1 is placed on one of two consecutive stages, and the second conveyor roller CR2 is placed on the other. However, this is not the only option, and as shown in Figure 4, the first conveyor roller CR1 may be placed on the first and fourth stages, and the second conveyor roller CR2 on the third and sixth stages, thus placing both conveyor rollers CR1 and CR2 with one stage skipped. Of course, it is also acceptable to place both conveyor rollers CR1 and CR2 with two or more stages skipped.

[0055] Furthermore, in the above embodiment, there are stages where neither the first conveyor roller CR1 nor the second conveyor roller CR2 is placed, such as the first and fourth stages of the multiple upper and lower stages. However, this is not limited to this configuration, and as shown in Figure 5, either the first conveyor roller CR1 or the second conveyor roller CR2 may be placed on all stages of the multiple upper and lower stages.

[0056] Furthermore, in the above embodiment, the arrangement of the pair of annealer rollers 9, 9 is the same between one side and the other side in the width direction of the glass ribbon 5 in each of the multiple upper and lower stages. However, this is not limited to this, and the arrangement may differ between one side and the other side. For example, the distance over which the first conveyor roller CR1 (second conveyor roller CR2) pushes the glass ribbon 5 may differ between one side and the other side. In this case, it is preferable to make the pushing distance longer on the side that is more prone to warping. Alternatively, the surface of the glass ribbon 5 that the first conveyor roller CR1 (second conveyor roller CR2) contacts may differ between one side and the other side. For example, when the first conveyor roller CR1 on one side contacts one side of the glass ribbon 5, the opposite side of this one side may be used as one side of the first conveyor roller CR1 on the other side, and the first conveyor roller CR1 on the other side may contact it. [Explanation of symbols]

[0057] 5 Glass Ribbons 8 Annealing furnace a1 axis a2 axis CR1 First Conveyor Roller CR2 Second Conveyor Roller D Overlapping length GR1 First Guide Roller GR2 Second Guide Roller L distance P1 Molding process P2 slow cooling process S1 One side S2 Other side

Claims

1. The molding process for forming glass ribbons, A slow cooling process in which the glass ribbon is slowly cooled in a slow cooling furnace while being conveyed downwards, A method for manufacturing a glass article, comprising: Inside the annealing furnace, a first conveyor roller and a second conveyor roller for conveying the glass ribbon are arranged with a vertical distance between them. In the aforementioned slow cooling process, the glass ribbon is conveyed while the first conveyor roller is brought into contact with one side of the glass ribbon and the second conveyor roller is brought into contact with the other side of the glass ribbon. A method for manufacturing a glass article, characterized in that, in the annealing step, the other side of the glass ribbon is exposed at the height position where the first conveyor roller is positioned, and the one side of the glass ribbon is exposed at the height position where the second conveyor roller is positioned.

2. The method for manufacturing a glass article according to claim 1, characterized in that the first conveyor roller and the second conveyor roller are arranged such that they overlap in the thickness direction of the glass ribbon when viewed from a direction parallel to the vertical direction.

3. Let L be the vertical distance (mm) from the axis of the first conveyor roller to the axis of the second conveyor roller. When D is the overlapping length (mm) of the first conveyor roller and the second conveyor roller in the thickness direction of the glass ribbon, The method for manufacturing a glass article according to claim 2, characterized in that the L / D value is 30 to 200.

4. When the strain point of the glass ribbon is T [°C], A method for manufacturing a glass article according to any one of claims 1 to 3, characterized in that the first conveying roller and the second conveying roller are placed in a region of the annealing furnace where the temperature is (T-100°C) or higher.

5. A first guide roller is positioned to face the first transport roller via the glass ribbon and to form a gap between itself and the glass ribbon, and A method for manufacturing a glass article according to any one of claims 1 to 3, characterized in that a second guide roller is arranged to face the second transport roller via the glass ribbon and to form a gap between itself and the glass ribbon.

6. A method for manufacturing a glass article according to any one of claims 1 to 3, characterized in that the thickness of the glass ribbon is 300 μm or less.

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