Glass plate manufacturing apparatus and method

Abstract

To provide an apparatus and method for manufacturing a glass plate, capable of preventing the surface of a support roller from deteriorating with heat from a glass ribbon and reducing manufacturing cost by achieving long life.SOLUTION: An apparatus 1 for manufacturing a glass plate includes: a molding furnace 2 for molding molten glass Gm into a glass ribbon Gr; a slow cooling furnace 3 for slowly cooling the glass ribbon Gr; a cooling chamber 4 for radiationally cooling the glass ribbon Gr; and a cutting chamber 5 for cutting the glass ribbon Gr into a predetermined length to obtain a glass plate G. The cooling chamber 4 includes a support roller 41 contacting the glass ribbon Gr and a cooler for cooling the surface of the support roller 41.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an improvement in an apparatus for producing a glass sheet and a method for producing a glass sheet. [Background technology]

[0002] As is well known, methods for manufacturing glass sheets include downdraw methods such as the overflow downdraw method, the slot downdraw method, and the redraw method, and the float method. In particular, the overflow downdraw method is known as a method for producing glass sheets with excellent surface quality, with very little surface waviness or roughness.

[0003] In the overflow downdraw method, a forming body having a wedge-shaped cross section installed in a forming furnace is used, and molten glass is continuously supplied to a groove provided at the top of the forming body. The supplied molten glass overflows from the groove, flows down along both sides of the forming body, and fuses at the lower end of the forming body to form a plate-shaped glass ribbon. The glass ribbon is transported on a conveying path extending vertically in the annealing furnace by pulling while holding both edges of the glass ribbon between a plurality of pulling rollers. At that time, since the atmospheric temperature in the annealing furnace is controlled, the glass ribbon is subjected to an annealing treatment, and the occurrence of unintended thermal distortion in the glass ribbon is suppressed. Since the glass ribbon in the annealing furnace is at a high temperature, the pulling rollers that hold the glass ribbon are required to have high heat resistance. For this reason, the surface of the pulling roller is made of an inorganic material containing ceramic fibers and a binder. The glass ribbon is then allowed to cool by being transported on a conveying path extending into a cooling chamber arranged at the bottom of the annealing furnace. Thereafter, the glass ribbon is transported to a cutting chamber and cut in the width direction at predetermined lengths to obtain glass plates.

[0004] In recent years, glass plates for displays have been getting larger. When the width dimension of the glass ribbon increases, the weight of the glass ribbon transported on the transport path increases. The weight of the glass ribbon may excessively pull the molten glass near the forming body, causing the glass ribbon to break and fall. The glass ribbon is sandwiched between multiple tension rollers, but as described above, the tension rollers are made of an inorganic material and have a small coefficient of friction between the glass ribbon. For this reason, slippage is likely to occur between the tension rollers and the glass ribbon, and the tension rollers cannot fully play the role of adjusting the transport speed of the glass ribbon. In order to prevent such a phenomenon, Patent Document 1 discloses a method in which support rollers made of a material (e.g., synthetic rubber) with a large coefficient of friction between the glass ribbon and the support rollers are installed in a cooling chamber to sandwich the glass ribbon. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-167014 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, for example, when the strain point of glass becomes high, the temperature of the glass ribbon fed into the cooling chamber also becomes high, and the amount of heat conducted from the glass ribbon to the support roller increases. In addition, even if the conveying speed of the glass ribbon is increased to improve manufacturing efficiency, the amount of heat conducted from the glass ribbon to the support roller increases. For this reason, even if the surface of the support roller is made of a highly heat-resistant rubber such as fluororubber or silicone rubber, the surface of the support roller deteriorates due to heat in a relatively short period of time, and frequent replacement is required.

[0007] An object of the present invention is to prevent the surface of the support roller from being deteriorated by heat from the glass ribbon, thereby extending the life of the support roller and reducing manufacturing costs. [Means for solving the problem]

[0008] The present invention, which has been invented to solve the above problems, is a glass sheet manufacturing apparatus including a forming furnace for forming molten glass into a glass ribbon, an annealing furnace for annealing the glass ribbon, a cooling chamber for cooling the glass ribbon, and a cutting chamber for cutting the glass ribbon to a predetermined length to obtain a glass sheet, wherein the cooling chamber includes a support roller that contacts the glass ribbon, and a cooling device for cooling the surface of the support roller. By directly cooling the surface of the support roller with the cooling device, deterioration of the surface of the support roller due to heat can be suppressed, and the life of the support roller can be extended. This can reduce the frequency of replacement of the support roller, thereby reducing manufacturing costs.

[0009] In the above configuration, it is preferable that the cooling device cools the surface of the support roller from the outside. If the surface of the support roller is made of a material with low thermal conductivity (e.g., rubber), the surface cannot be efficiently cooled from the inside of the support roller. By cooling the surface of the support roller from the outside, the surface of the support roller can be efficiently cooled regardless of the material of the surface of the support roller.

[0010] In the above configuration, it is preferable that the support rollers are arranged in a row along the longitudinal direction of the glass ribbon to form a support roller group, and the cooling device is provided on the support roller in the support roller group that contacts a portion of the glass ribbon that is at 200°C or higher. With this configuration, it is possible to selectively cool only the support rollers that have a high surface temperature and a high rate of deterioration among the multiple support rollers. This makes it possible to reduce the number of cooling devices to be installed and to reduce equipment costs.

[0011] In the above configuration, the material of the surface of the support roller is preferably rubber. Since rubber has a large coefficient of friction with respect to glass, a large frictional force can be obtained with a small contact pressure. Therefore, the contact pressure of the support roller with respect to the glass ribbon can be reduced, and damage to the glass ribbon can be prevented. Furthermore, since the physical properties of rubber, such as its hardness, flexibility, and surface smoothness, can be easily adjusted, a material that can reliably support the glass ribbon can be easily obtained.

[0012] In the above configuration, the heat resistance temperature of the rubber is preferably 200°C or higher. With such a configuration, it is possible to reduce the number of support rollers whose surfaces are heated to the heat resistance temperature or higher by contacting the glass ribbon. This makes it possible to reduce the number of cooling devices to be installed, thereby reducing equipment costs. Here, the heat resistance temperature means the maximum temperature within the range at which the rubber is not deformed by heat, does not become uselessly sticky due to heat, and can maintain its physical properties at room temperature.

[0013] In the above configuration, the cooling device is preferably a cooling roller that contacts the surface of the support roller. Examples of cooling devices for cooling the surface of the support roller include a cooling roller or a cooling plate that contacts the surface of the support roller, a coolant spraying device, and the like. When a cooling plate is provided, there are problems such as wear of the surface of the support roller and an increase in the torque required to rotate the support roller due to friction between the surface of the support roller and the cooling plate. When a coolant spraying device is provided, there are problems such as disturbance of the atmospheric temperature and scattering of glass powder due to airflow generated in the glass sheet manufacturing device. By using a configuration in which a cooling roller is contacted, the surface of the support roller can be cooled without causing such problems.

[0014] In the above configuration, it is preferable that the cooling roller has a flow path therein for circulating a refrigerant. With such a configuration, heat conducted from the surface of the support roller to the cooling roller can be rapidly conducted to the refrigerant. Therefore, the surface of the support roller in contact with the cooling roller can be efficiently cooled.

[0015] In the above-mentioned configuration, the refrigerant is preferably a cooling liquid. With this configuration, the surface of the support roller in contact with the cooling roller can be cooled more efficiently.

[0016] In the above configuration, the glass ribbon preferably has a width of 2000 mm or more. With such a configuration, the weight of the glass ribbon becomes large, and slippage between the glass ribbon and the support rollers becomes likely to occur. Therefore, the effect of the support rollers in preventing the glass ribbon from slipping becomes significant.

[0017] The method for producing a glass sheet according to the present invention includes a forming step of forming molten glass into a glass ribbon, an annealing step of annealing the glass ribbon, a cooling step of allowing the glass ribbon to cool while being in contact with a support roller, and a cutting step of cutting the glass ribbon to a predetermined length to obtain a glass sheet, and is characterized in that the cooling step includes cooling the surface of the support roller using a cooling device. The surface of the support roller is in contact with the high-temperature glass ribbon, so that the temperature of the surface of the support roller increases and deteriorates in a relatively short period of time. By directly cooling the surface of the support roller with the cooling device, deterioration due to heat of the surface of the support roller can be suppressed and the life of the support roller can be extended. This reduces the frequency of replacement of the support roller, thereby reducing manufacturing costs. Effect of the Invention

[0018] According to the present invention, the surface of the support roller can be efficiently cooled to extend its life, thereby reducing manufacturing costs. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a front view showing an apparatus for producing a glass sheet according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line A--A of FIG. [Diagram 3] FIG. 3 is a perspective view showing a main part of a support roller according to an embodiment of the present invention. [Figure 4]FIG. 4 is a cross-sectional view showing a cooling roller according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view taken along line BB of FIG. [Figure 6] FIG. 6 is a cross-sectional view showing a cooling roller according to another embodiment of the present invention. [Figure 7] FIG. 7 is a side view showing a main part of a support roller and a cooling device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of a glass sheet manufacturing apparatus and a glass sheet manufacturing method according to the present invention will be described with reference to the accompanying drawings.

[0021] 1 and 2, the glass sheet manufacturing apparatus 1 according to the present embodiment includes a forming furnace 2 for forming molten glass Gm into a glass ribbon Gr, an annealing furnace 3 for annealing the glass ribbon Gr, a cooling chamber 4 for naturally cooling the glass ribbon Gr, and a cutting chamber 5 for cutting the glass ribbon Gr to a predetermined length to obtain a glass sheet G. The glass sheet manufacturing method according to the present embodiment is carried out using the glass sheet manufacturing apparatus 1.

[0022] The forming furnace 2 is a space surrounded by a furnace wall 11, and includes a forming body 21 having a wedge-shaped cross section, and a pair of edge rollers 22 provided below the forming body 21. In the forming furnace 2, molten glass Gm is continuously supplied to a groove provided in a top 211 of the forming body 21. This molten glass Gm is formed, for example, by heating and melting glass raw materials or cullets in a melting furnace, and is subjected to a fining treatment or a stirring treatment as necessary.

[0023] The supplied molten glass Gm overflows from the grooves, flows down along both side surfaces 212 of the forming body 21, and fuses at the lower end 213 of the forming body 21. As a result, a plate-shaped glass ribbon Gr is formed. Both edge portions of the glass ribbon Gr are cooled while being pinched from the front and back by a set of four edge rollers 22. As a result, shrinkage of the glass ribbon Gr in the width direction is minimized.

[0024] The annealing furnace 3 is a space surrounded by a furnace wall 11, and includes a plurality of pairs of pulling rollers 31. The plurality of pulling rollers 31 are arranged along the longitudinal direction of the glass ribbon Gr, and pull the glass ribbon Gr downward while pulling it in the width direction so that the glass ribbon Gr does not shrink in the width direction due to surface tension or the like. The inside of the annealing furnace 3 is set to have a predetermined temperature gradient by a heater (not shown). As the glass ribbon Gr is transported in the annealing furnace 3, the temperature of the glass ribbon Gr gradually decreases, and the glass ribbon Gr is annealed to a temperature below the strain point. This makes it possible to suppress the occurrence of unintended thermal distortion inside the glass ribbon Gr.

[0025] The pulling rollers 31 are made of an inorganic material containing ceramic fibers and a binder. The roller shaft of the pulling roller 31 is connected to a power source (e.g., a motor) not shown, and is controlled to rotate at a constant speed (circumferential speed or rotation speed). In this embodiment, three pairs of pulling rollers 31 are arranged along the longitudinal direction of the glass ribbon Gr, but this is not limited thereto. Depending on the temperature, width, and transport speed of the glass ribbon Gr, the size of the annealing furnace 3, and the like, the number of pairs of the pulling rollers 31 may be two pairs or less or four pairs or more. In addition, the roller shaft of the pulling roller 31 may be controlled to rotate with a constant torque.

[0026] The cooling chamber 4 includes support rollers 41, and the support rollers 41 are arranged in a row along the longitudinal direction of the glass ribbon Gr to form a support roller group 41A. The support rollers 41 move the glass ribbon Gr downward while pinching both edges of the glass ribbon Gr from the front and back. The cooling chamber 4 does not include a heater and allows the glass ribbon Gr to cool. The width of the glass ribbon Gr is preferably 2000 mm or more, more preferably 2500 mm or more, and even more preferably 3000 mm or more. When the width of the glass ribbon Gr is large in this way, the weight of the glass ribbon Gr becomes large, and slippage is likely to occur between the glass ribbon Gr and the support rollers 41. Therefore, the effect of the support rollers 41 in preventing the glass ribbon Gr from slipping becomes significant.

[0027] As shown in FIG. 3, the support roller 41 has a rubber surface layer 413 attached to a metal shaft 411 via a metal core 412. The surface layer 413 contacts the glass ribbon Gr and corresponds to the surface of the support roller 41 of the present invention. The material of the surface layer 413 can be synthetic rubber such as silicone rubber or fluororubber. The heat resistance temperature of the rubber of the surface layer 413 is preferably 200° C. or higher, more preferably 250° C. or higher, and even more preferably 300° C. or higher. The shaft 411 is connected to a power source (e.g., a motor) not shown, and is controlled to rotate at a constant speed (circumferential speed or rotation speed). In this embodiment, four pairs of support rollers 41 are arranged along the longitudinal direction of the glass ribbon Gr, but this is not limited thereto. Depending on the temperature, width, and transport speed of the glass ribbon Gr, the size of the cooling chamber 4, and the like, the number of pairs of the support rollers 41 may be three pairs or less or five pairs or more. The shaft 411 of the support roller 41 may be controlled to rotate with a constant torque.

[0028] The cutting chamber 5 has a cutting mechanism (not shown) that cuts the cooled glass ribbon Gr in the width direction at predetermined lengths to obtain glass sheets G. The obtained glass sheets G are transported by a transport device (not shown) to subsequent processes such as a removal process in which both ends in the width direction of the glass sheet G are cut and removed, various inspection processes, and a packaging process. In this manner, the glass sheets G are manufactured.

[0029] As shown in FIGS. 1 and 2, the cooling chamber 4 of the present embodiment includes a cooling roller 42 as a cooling device for cooling the surface of a support roller 41. The cooling roller 42 is a cooling device for cooling the surface of a support roller 41.

[0030] As shown in Figs. 4 and 5, the cooling roller 42 has a roller part 421 that contacts the surface of the support roller 41, a shaft part 425 that holds the roller part 421, and a flow path 422 through which the cooling liquid Lc (e.g., water) flows inside. The roller part 421 is held by the shaft part 425 via a bearing 426, and can rotate according to the rotation of the support roller 41. The roller part 421 is made of a metal material such as stainless steel, and can quickly conduct heat conducted from the surface of the support roller 41 to the roller part 421 to the cooling liquid Lc. The bearing 426 is provided with a seal structure to prevent leakage of the cooling liquid Lc. The flow path 422 is connected to an inflow path 423 and an outflow path 424 provided inside the shaft part 425. As shown in Fig. 5, an inflow path 423 may be provided on one side of the shaft portion 425 in the longitudinal direction, and an outflow path 424 may be provided on the opposite side of the shaft portion 425. Alternatively, as shown in Fig. 6, one side of the shaft portion 425 in the longitudinal direction may have a double pipe structure, and the inflow path 423 and the outflow path 424 may be provided on one side. The cooling liquid Lc is supplied from a cooling liquid source (not shown) through the inflow path 423 to the flow path 422. After cooling the roller portion 421 in the flow path 422, the cooling liquid Lc is discharged through the outflow path 424.

[0031] According to the above-described glass plate manufacturing apparatus and glass plate manufacturing method, the surface of the support roller 41 can be efficiently cooled by the cooling device (cooling roller 42), thereby extending the life of the support roller 41 and reducing the frequency of replacement, thereby reducing manufacturing costs.

[0032] As shown in Fig. 1 and Fig. 2, among the support roller group 41A arranged along the longitudinal direction of the glass ribbon Gr, the support roller 41 that contacts the portion of the glass ribbon Gr that is 200 ° C or more is preferably provided with the cooling roller 42 in a state of contacting the surface of the support roller 41. According to such a configuration, the number of cooling devices to be installed can be reduced, and therefore the equipment cost can be reduced. In the present embodiment, the cooling roller 42 is provided on three pairs of support rollers 41 from the top among the multiple pairs of support rollers 41, but this is not limited thereto. Depending on the temperature and transport speed of the glass ribbon Gr to be carried into the cooling chamber 4, the number of pairs of support rollers 41 that the cooling roller 42 contacts may be two pairs or less or four pairs or more.

[0033] In the present embodiment, the cooling roller 42 is brought into contact with the support roller 41 from above, but the cooling roller 42 may be brought into contact with the support roller 41 from below, beside, or obliquely. From the viewpoint of protecting the support roller 41 from glass fragments that fall when the glass ribbon Gr is broken, it is preferable to bring the cooling roller 42 into contact with the support roller 41 from above.

[0034] When the surface of the support roller 41 deteriorates, the torque required to rotate the support roller 41 at a constant speed changes. Therefore, it is preferable to monitor the deterioration state of the surface of the support roller 41 by measuring the torque of the power source connected to the shaft portion 411 and detecting the change in the torque over time. When a motor is used as the power source, the torque of the motor can be measured by measuring the load current of the motor using a sensor.

[0035] The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

[0036] In the above embodiment, the case where the present invention is applied to the production of a glass sheet by the overflow downdraw method has been described, but the present invention is not limited thereto. The present invention can also be applied to other glass sheet production methods in which sheet drawing is performed while pulling the glass ribbon Gr using rollers, such as a slot downdraw method.

[0037] In the above embodiment, the cooling liquid Lc is used as the refrigerant, but the present invention is not limited to this, and a cooling gas may be used. From the viewpoint of efficiently cooling the support roller 41, it is preferable to use the cooling liquid Lc.

[0038] In the above embodiment, the surface of the support roller 41 is cooled by contacting the cooling roller 42, but the present invention is not limited to this. As shown in FIG. 7, a cooling plate 43 may be contacted to the surface of the support roller 41 as a cooling device, or a duct 44 that blows a cooling gas Gc onto the surface of the support roller 41 may be used as the cooling device. When the cooling plate 43 is contacted from above the support roller 41, the support roller 41 can be protected from falling objects when the glass ribbon Gr is damaged on the conveying path. In addition, a flow path for circulating a refrigerant may be provided inside the cooling plate 43. In addition, the cooling device may be configured by combining the cooling roller 42, the cooling plate 43, and the duct 44.

[0039] In the above embodiment, the two support rollers 41 that come into contact with both edge portions of the glass ribbon Gr share a common shaft portion 411, and both ends of the shaft portion 411 are supported, but the shaft portion 411 may be divided to provide the shaft portion 411 on each of the two support rollers 41, and the shaft portion 411 may be supported by a cantilever. Similarly, in the above embodiment, the two tension rollers 31 that come into contact with both edge portions of the glass ribbon Gr share a common roller shaft, and both ends of the roller shaft are supported, but the roller shaft may be divided to provide the roller shaft on each of the two tension rollers 31, and the roller shaft may be supported by a cantilever.

[0040] In the above embodiment, two core portions 412 and surface layer portions 413 are provided on one shaft portion 411 to support both edge portions of the glass ribbon Gr, but the present invention is not limited to this. Three or more core portions 412 and surface layer portions 413 may be provided on one shaft portion 411 to support both edge portions and a middle portion of the glass ribbon Gr. With such a configuration, the contact area between the support roller 41 and the glass ribbon Gr can be increased, and therefore the glass ribbon Gr can be supported with a smaller contact pressure. [Industrial Applicability]

[0041] INDUSTRIAL APPLICABILITY The present invention can be suitably used to efficiently cool the surface of a support roller and extend its life, thereby reducing manufacturing costs. [Explanation of symbols]

[0042] 1 Manufacturing equipment 2 Molding furnace 3 Annealing furnace 4 Cooling room 41 Support roller 41A Support roller group 42 Cooling roller 422 Channel 5 Cutting chamber Gr Glass ribbon Gm Molten Glass lc coolant

Claims

1. A glass sheet manufacturing apparatus including: a forming furnace for forming molten glass into a glass ribbon; an annealing furnace for annealing the glass ribbon; a cooling chamber for cooling the glass ribbon; and a cutting chamber for cutting the glass ribbon to a predetermined length to obtain a glass sheet, The cooling chamber includes a support roller that contacts the glass ribbon and a cooling device that cools a surface of the support roller, The apparatus for manufacturing a glass sheet, wherein the cooling device cools the surface of the support roller from outside.

2. The support rollers are configured to configure a support roller group by arranging a plurality of the support rollers in a line along the longitudinal direction of the glass ribbon, The apparatus for manufacturing a glass sheet according to claim 1 , wherein the cooling device is provided on one of the support rollers that comes into contact with a portion of the glass ribbon that is heated to 200° C. or higher.

3. 3. The apparatus for manufacturing a glass sheet according to claim 1, wherein the material of the surface of the support roller is rubber.

4. 4. The apparatus for manufacturing a glass sheet according to claim 3, wherein the heat-resistant temperature of the rubber is 200° C. or higher.

5. 5. The apparatus for producing a glass sheet according to claim 1, wherein the cooling device is a cooling roller that comes into contact with the surface of the support roller.

6. 6. The apparatus for manufacturing a glass sheet according to claim 5, wherein the cooling roller has a flow path therein for circulating a coolant.

7. 7. The apparatus for manufacturing a glass sheet according to claim 6, wherein the refrigerant is a cooling liquid.

8. 8. The apparatus for manufacturing a glass sheet according to claim 1, wherein the glass ribbon has a width of 2000 mm or more.

9. A method for producing a glass sheet, comprising: a forming step of forming molten glass into a glass ribbon; an annealing step of annealing the glass ribbon; a cooling step of allowing the glass ribbon to cool while being in contact with a support roller; and a cutting step of cutting the glass ribbon to a predetermined length to obtain a glass sheet, In the cooling step, a surface of the support roller is cooled using a cooling device, The method for manufacturing a glass sheet, wherein the cooling device cools the surface of the support roller from outside.

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