JP2014214062A - Method and apparatus for manufacturing glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for manufacturing a glass plate, capable of manufacturing a high quality glass plate.SOLUTION: A method for manufacturing a glass plate includes a molding step and a cooling step. The molding step is the step of running a molten glass 2 down from a molding 62 to mold a glass plate 3. The cooling step is the step of cooling the glass plate 3 while conveying it downward. In the cooling step, heaters 84a-84g form a temperature distribution in the width direction of the glass plate 3 in the glass plate 3. The heater 84a is divided into a plurality of divided heaters 85a1-85a5 in the width direction. The heater 84b is divided into a plurality of divided heaters 85b1-85b5 in the width direction. At least one of the divided heaters 85a1-85a5 is adjacent to the plurality of divided heaters 85b1-85b5 in a conveying direction.

Description

  The present invention relates to a glass plate manufacturing method and a glass plate manufacturing apparatus.

  The glass plate used for flat panel displays (FPD), such as a liquid crystal display and a plasma display, is manufactured by the down draw method, for example. In the downdraw method, a glass plate formed from molten glass is cooled while being conveyed downward and cut into a predetermined size. The cut glass plate is packed and shipped through an end face processing step, a surface cleaning step, an inspection step, and the like.

  As disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2001-31435) and Patent Document 2 (Japanese Patent Laid-Open No. 2007-112665), a glass formed from molten glass in the glass plate manufacturing process by the downdraw method. A method is known in which a plate is heated by heat treatment means while being conveyed downward by a roll. In this method, the temperature of the glass plate is adjusted by heat treatment means facing the glass plate surface. The heat treatment means is composed of a plurality of heaters divided along the conveying direction of the glass plate and the width direction of the glass plate. The temperature of each heater can be controlled individually. Therefore, the heat treatment means can form a predetermined temperature distribution on the glass plate in the width direction of the glass plate. While the temperature distribution in the width direction of the glass plate is formed on the glass plate using the heat treatment means, the warp and distortion of the glass plate can be reduced by gradually cooling the glass plate.

  In the glass plate manufacturing method disclosed in Patent Document 1, in order to form a temperature distribution in the width direction of the glass plate on the glass plate, a plurality of heaters are arranged adjacent to each other along the width direction of the glass plate, and The temperature of each heater can be individually controlled. However, for example, when a heating wire is used as the heater, a region between two heaters adjacent in the width direction of the glass plate is a region where there is no heating wire. The region between heaters where no heating wire exists is a region where the temperature is locally low in the entire region occupied by a plurality of heaters arranged along the width direction of the glass plate. Therefore, on the surface of the glass plate facing the plurality of heaters arranged in the width direction, the surface facing the inter-heater region is also a region where the temperature is locally low. That is, when a heating wire is used as the heater, the plurality of heaters arranged in the width direction may form a non-uniform temperature distribution in which the temperature locally decreases on the glass plate surface. And in the area | region where the temperature on the glass plate surface changes rapidly like the area | region where the temperature on the glass plate surface is locally low, the curvature and distortion of a glass plate are easy to generate | occur | produce. Therefore, in order to produce a high-quality glass plate, it is preferable not to have a temperature distribution in which the temperature rapidly changes in the width direction of the glass plate in the step of gradually cooling while conveying the glass plate downward. .

  In the glass plate manufacturing method disclosed in Patent Document 2, it is described that a local temperature decrease of the heater is suppressed by providing a density in the arrangement density of heating wires. However, in this method, it is difficult to form a suitable temperature distribution in the width direction of the glass plate in the production of the glass plate having a high strain point, and the procurement cost of the heater increases.

  The objective of this invention is providing the glass plate manufacturing method and glass plate manufacturing apparatus which can manufacture a high quality glass plate.

  The glass plate manufacturing method according to the present invention includes a forming step and a cooling step. The forming step is a step of forming a glass plate by causing molten glass to flow down from the formed body. A cooling process is a process of cooling a glass plate, conveying the glass plate shape | molded by the formation process below. In the cooling step, a plurality of heating means arranged along the conveyance direction in which the glass plate is conveyed radiates heat toward the glass plate, and forms a temperature distribution in the width direction of the glass plate on the glass plate. The first heating means which is one of the plurality of heating means is divided into a plurality of first divided heating means along the width direction. The second heating means that is the heating means adjacent to the first heating means in the transport direction is divided into a plurality of second divided heating means along the width direction. At least one first divided heating means is adjacent to the plurality of second divided heating means in the transport direction. The number of sets of the first divided heating means and the second divided heating means that can be adjacent in the transport direction is larger than at least one of the number of the first divided heating means and the number of the second divided heating means.

  In the glass plate manufacturing method according to the present invention, the glass plate formed at the lower end of the formed body is rapidly cooled to the vicinity of the annealing point of the glass plate, and then gradually cooled while being conveyed downward by a roll or the like. In the step of gradually cooling the glass plate, the temperature of the glass plate is adjusted by radiant heat from a plurality of heating means. The heating means is installed to face the glass plate surface and radiates heat toward the glass plate surface. The heating means is divided into a plurality of divided heating means along the width direction of the glass plate.

  In this glass plate manufacturing method, with respect to two heating means adjacent in the glass plate conveyance direction, the division heating means of one heating means is adjacent to the plurality of division heating means of the other heating means in the glass plate conveyance direction. doing. In other words, the gap between the two divided heating means adjacent in the width direction of the glass plate is adjacent to the divided heating means of the other heating means in the conveyance direction of the glass plate. Thus, the division heating means of each heating means are alternately arranged along the conveyance direction of the glass plate. By arranging the divided heating means of each heating means in this way, the number of divided heating means of each heating means can be reduced, so that the effective area of the heating means increases and the manufacturing cost of the glass plate decreases. . Moreover, the smaller the number of divided heating means of each heating means, the smaller the number of gaps between the adjacent divided heating means in the width direction of the glass plate. Since the glass plate surface facing the gap between the divided heating means is difficult to be heated, the temperature distribution in the width direction of the glass plate surface locally decreases in the region facing the gap between the divided heating means. Show the trend. That is, the smaller the number of gaps between the divided heating means, the smaller the number of regions where the temperature of the glass plate surface locally decreases in the width direction of the glass plate. As a result, it is suppressed that the glass plate heated by the heating means has a temperature distribution in which the temperature locally changes in the width direction of the glass plate. In a region where the temperature on the surface of the glass plate changes locally, internal stress due to a temperature difference from the surroundings tends to occur, and the warp and distortion of the glass plate tend to occur. Therefore, this glass plate manufacturing method suppresses the warp and distortion of the glass plate by forming a good temperature distribution on the glass plate along the width direction of the glass plate, and can manufacture a high-quality glass plate. it can.

  In the glass plate manufacturing method according to the present invention, the cooling step preferably includes a first cooling step, a second cooling step, and a third cooling step. In the first cooling step, the temperature of the glass plate formed in the forming step is lowered to the annealing point. In the second cooling step, the temperature of the glass plate decreases from the annealing point to the strain point. In the third cooling step, the temperature of the glass plate is lowered from the strain point to a temperature 200 ° C. lower than the strain point. In each of the first cooling step, the second cooling step, and the third cooling step, the first heating means and the second heating means form a temperature distribution in the width direction on the glass plate.

  In the glass plate manufacturing method according to the present invention, in the cooling step, the heating means has a temperature distribution in the width direction so that the temperature difference of the glass plate in the width direction gradually decreases as the glass plate is conveyed downward. It is preferable to form on a glass plate.

  The glass plate manufacturing apparatus according to the present invention includes a forming unit and a cooling unit. The forming unit overflows the molten glass from the formed body and fuses the molten glass at the lower end of the formed body to form a glass plate. A cooling part cools a glass plate, conveying the glass plate shape | molded by the formation part below. The cooling unit has a plurality of heating means arranged along the conveyance direction in which the glass plate is conveyed. The heating means radiates heat toward the glass plate to form a temperature distribution in the width direction of the glass plate on the glass plate. The first heating means which is one of the plurality of heating means is divided into a plurality of first divided heating means along the width direction. The second heating means that is the heating means adjacent to the first heating means in the transport direction is divided into a plurality of second divided heating means along the width direction. At least one first divided heating means is adjacent to the plurality of second divided heating means in the transport direction. The number of sets of the first divided heating means and the second divided heating means that can be adjacent in the transport direction is larger than at least one of the number of the first divided heating means and the number of the second divided heating means.

  The glass plate manufacturing method and the glass plate manufacturing apparatus according to the present invention suppress the warpage and distortion of the glass plate by forming a good temperature distribution on the glass plate along the width direction of the glass plate, and high quality. The glass plate can be manufactured.

It is a flowchart of the glass plate manufacturing method which concerns on embodiment. It is a schematic diagram of the glass plate manufacturing apparatus which concerns on embodiment. It is a front view of the shaping | molding apparatus of a glass plate manufacturing apparatus. It is a side view of the shaping | molding apparatus of a glass plate manufacturing apparatus. It is a front view of the heater of a shaping | molding apparatus. It is a table of the output of the division | segmentation heater of a heater. It is a table of the output of the divided heater of two heaters adjacent in the vertical direction and the output of a heater pair composed of two divided heaters adjacent in the vertical direction. It is a table of the output of the divided heater of two heaters adjacent in the vertical direction and the output of a heater pair composed of two divided heaters adjacent in the vertical direction. It is a table of the output of the divided heater of two heaters adjacent in the vertical direction and the output of a heater pair composed of two divided heaters adjacent in the vertical direction. It is a graph showing the temperature distribution of the horizontal direction of the glass plate surface facing a heater. It is a front view of the conventional heater as a reference example. It is a graph showing the temperature distribution of the horizontal direction of the glass plate surface facing a conventional heater as a reference example.

(1) Configuration of Glass Plate Manufacturing Apparatus An embodiment of a glass plate manufacturing method and a glass plate manufacturing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of a glass plate manufacturing method according to the present embodiment.

  As shown in FIG. 1, the glass plate manufacturing method according to the present embodiment mainly includes a melting step S1, a clarification step S2, a stirring step S3, a forming step S4, a cooling step S5, and a cutting step S6. including.

In the melting step S1, the glass raw material is heated to obtain molten glass. The molten glass is stored in a melting tank and energized and heated to have a desired temperature. A fining agent is added to the glass raw material. From the viewpoint of reducing environmental burden, SnO ₂ is used as a clarifying agent.

In the clarification step S2, the molten glass obtained in the melting step S1 flows through the clarification tube, and the gas contained in the molten glass is removed, whereby the molten glass is clarified. First, in the refining step S2, the temperature of the molten glass is raised. The refining agent added to the molten glass causes a reduction reaction by raising the temperature and releases oxygen. Bubbles containing gas components such as CO ₂ , N ₂ and SO ₂ contained in the molten glass absorb oxygen generated by the reductive reaction of the fining agent. Bubbles that have grown by absorbing oxygen float on the liquid surface of the molten glass, break up and disappear. The gas contained in the extinguished bubbles is discharged into the gas phase space inside the clarification tube and discharged to the outside air. Next, in the refining step S2, the temperature of the molten glass is lowered. Thereby, the reduced fining agent causes an oxidation reaction and absorbs gas components such as oxygen remaining in the molten glass.

  In the stirring step S3, the molten glass from which the gas has been removed in the refining step S2 is stirred, and the components of the molten glass are homogenized. Thereby, the nonuniformity of the composition of the molten glass which is the cause of the striae of the glass plate is reduced.

  In the forming step S4, a glass plate is continuously formed from the molten glass homogenized in the stirring step S3 using the overflow downdraw method.

  In the cooling step S5, the glass plate continuously formed in the forming step S4 is cooled. The cooling step S5 includes a gradual cooling step of gradually cooling the glass plate while adjusting the temperature of the glass plate so that the glass plate is not distorted and warped.

  In the cutting step S6, the glass plate cooled in the cooling step S5 is cut into a predetermined size, and thereafter, the end surface of the cut glass plate is ground and polished, and the glass plate is cleaned. Further, the glass plate is inspected for defects such as scratches, and the glass plate that has passed the inspection is packed and shipped as a product.

  FIG. 2 is a schematic diagram illustrating an example of the glass plate manufacturing apparatus 1 according to the present embodiment. The glass plate manufacturing apparatus 1 includes a melting tank 10, a clarification tube 20, a stirring device 30, a forming device 40, and transfer tubes 50a, 50b, and 50c. The transfer pipe 50 a connects the melting tank 10 and the clarification pipe 20. The transfer pipe 50 b connects the clarification pipe 20 and the stirring device 30. The transfer pipe 50 c connects the stirring device 30 and the molding device 40.

  The molten glass 2 obtained in the melting tank 10 in the melting step S1 passes through the transfer pipe 50a and flows into the clarification pipe 20. The molten glass 2 clarified by the clarification tube 20 in the clarification step S2 passes through the transfer tube 50b and flows into the stirring device 30. The molten glass 2 stirred by the stirring device 30 in the stirring step S3 passes through the transfer pipe 50c and flows into the molding device 40. In the forming step S <b> 4, the glass plate 3 is formed from the molten glass 2 by the forming apparatus 40. In the cooling step S5, the glass plate 3 is cooled while being conveyed downward. In the cutting step S6, the cooled glass plate 3 is cut into a predetermined size. The width | variety of the cut | disconnected glass plate is 500 mm-3500 mm, for example, and length is 500 mm-3500 mm, for example. The thickness of the glass plate is, for example, 0.2 mm to 0.8 mm.

The glass plate manufactured by the glass plate manufacturing apparatus 1 is particularly suitable as a glass plate for a flat panel display (FPD) such as a liquid crystal display, a plasma display, and an organic EL display. As the glass plate for FPD, non-alkali glass or alkali-containing glass is used. A glass plate for FPD has a high viscosity at a high temperature. For example, a molten glass on which a glass plate for FPD is formed has a viscosity of 10 ^2.5 poise at 1500 ° C.

In the melting tank 10, the glass raw material is melted to obtain the molten glass 2. The glass raw material is prepared so that the glass plate which has a desired composition can be obtained. As an example of the composition of the glass plate, non-alkali glass suitable as a glass plate for FPD is SiO ₂ : 50 mass% to 70 mass%, Al ₂ O ₃ : 0 mass% to 25 mass%, B ₂ O ₃ : 1% by mass to 15% by mass, MgO: 0% by mass to 10% by mass, CaO: 0% by mass to 20% by mass, SrO: 0% by mass to 20% by mass, BaO: 0% by mass to 10% by mass . Here, the total content of MgO, CaO, SrO and BaO is 5% by mass to 30% by mass.

Moreover, you may use the alkali trace amount glass which contains a trace amount of alkali metals as a glass plate for FPD. Alkaline trace containing glass 'includes a ₂ O, preferably, 0.2 wt% to 0.5 wt% R' of R 0.1 wt% to 0.5 wt% including the ₂ O. Here, R ′ is at least one selected from Li, Na and K. The total content of R ′ ₂ O may be less than 0.1% by mass.

Further, the glass plate manufactured by the glass plate manufacturing apparatus _1, SnO 2: 0.01 wt% to 1 wt% (preferably 0.01 mass% to 0.5 _{mass%), Fe 2 O 3:} 0 You may further contain mass%-0.2 mass% (preferably 0.01 mass%-0.08 mass%). The glass plate manufactured by the glass plate manufacturing apparatus 1, from the viewpoint of environmental load reduction, substantially free of _{As 2 O 3, Sb 2 O} 3 , and PbO.

  The glass raw material prepared to have the above composition is charged into the melting tank 10 using a raw material charging machine (not shown). The raw material input machine may input a glass raw material using a screw feeder, or may input a glass raw material using a bucket. In the melting tank 10, the glass raw material is heated and melted at a temperature according to its composition. In the melting tank 10, the high temperature molten glass 2 of 1500 degreeC-1600 degreeC is obtained, for example. In the melting tank 10, the molten glass 2 between the electrodes may be energized and heated by passing a current between at least one pair of electrodes formed of molybdenum, platinum, tin oxide or the like. The glass raw material may be supplementarily heated by a burner flame.

  The molten glass 2 obtained in the melting tank 10 passes through the transfer pipe 50 a from the melting tank 10 and flows into the clarification pipe 20. The clarification tube 20 and the transfer tubes 50a, 50b and 50c are tubes made of platinum or a platinum alloy. The clarification tube 20 is provided with heating means as in the melting tank 10. In the clarification tube 20, the molten glass 2 is further heated to be clarified. For example, in the clarification tube 20, the temperature of the molten glass 2 is raised to 1500 ° C to 1700 ° C.

  The molten glass 2 clarified in the clarification tube 20 passes through the transfer tube 50 b from the clarification tube 20 and flows into the stirring device 30. The molten glass 2 is cooled when passing through the transfer tube 50b. In the stirring device 30, the molten glass 2 is stirred at a temperature lower than the temperature of the molten glass 2 that passes through the clarification tube 20. For example, in the stirring device 30, the temperature of the molten glass 2 is 1250 ° C. to 1450 ° C., and the viscosity of the molten glass 2 is 500 poise to 1300 poise. The molten glass 2 is stirred and homogenized in the stirring device 30.

  The molten glass 2 homogenized by the stirring device 30 flows from the stirring device 30 through the transfer pipe 50 c and flows into the molding device 40. The molten glass 2 is cooled so as to have a viscosity suitable for forming the molten glass 2 when passing through the transfer tube 50c. For example, the molten glass 2 is cooled to around 1200 ° C.

  In the shaping | molding apparatus 40, the glass plate 3 is shape | molded from the molten glass 2 by the overflow downdraw method. Next, the configuration and operation of the molding apparatus 40 will be described.

(2) Configuration of Molding Device FIG. 3 is a front view of the molding device 40. FIG. 3 shows the forming apparatus 40 viewed along a direction perpendicular to the surface of the glass plate 3 formed by the forming apparatus 40. FIG. 4 is a side view of the molding apparatus 40.

  The molding apparatus 40 has a space surrounded by a furnace wall (not shown). This space is a space in which the glass plate 3 is formed from the molten glass 2 and cooled, and is composed of three spaces: an overflow chamber 60, a forming chamber 70, and a cooling chamber 80.

  The molding step S4 is performed in the overflow chamber 60, and the cooling step S5 is performed in the forming chamber 70 and the cooling chamber 80. The overflow chamber 60 is a space in which the molten glass 2 supplied from the stirring device 30 to the forming device 40 via the transfer pipe 50 c is formed on the glass plate 3. The forming chamber 70 is a space below the overflow chamber 60, and is a space where the glass plate 3 is rapidly cooled to the vicinity of the annealing point of the glass. The cooling chamber 80 is a space below the forming chamber 70 and is a space where a slow cooling process in which the glass plate 3 is gradually cooled is performed. The slow cooling step is preferably performed in a temperature range from the slow cooling point of the glass to a temperature 200 ° C. lower than the strain point of the glass.

  The molding apparatus 40 mainly includes a molded body 62, an upper partition member 64, a cooling roll 72, a temperature adjustment unit 74, a lower partition member 76, pulling rolls 82a to 82g, heaters 84a to 84g, and a heat insulating plate. 86a-86g and a control apparatus (not shown) are comprised. Next, each component of the shaping | molding apparatus 40 is demonstrated.

(2-1) Molded Body The molded body 62 is installed in the overflow chamber 60. The formed body 62 is used to overflow the molten glass 2 and form the glass plate 3. As shown in FIG. 4, the molded body 62 has a pentagonal cross-sectional shape similar to a wedge shape. The sharp end of the cross-sectional shape of the molded body 62 corresponds to the lower end 62 a of the molded body 62. The molded body 62 is made of refractory bricks.

  A groove 62 b is formed on the upper end surface of the molded body 62 along the longitudinal direction of the molded body 62. A transfer pipe 50c communicating with the groove 62b is attached to an end of the molded body 62 in the longitudinal direction. The groove 62b is formed so as to gradually become shallower from one end communicating with the transfer pipe 50c toward the other end.

The molten glass 2 sent to the shaping | molding apparatus 40 from the stirring apparatus 30 is poured into the groove | channel 62b of the molded object 62 via the transfer pipe 50c. The molten glass 2 overflowed from the groove 62 b of the molded body 62 flows down along both side surfaces of the molded body 62 and merges in the vicinity of the lower end 62 a of the molded body 62. The joined molten glass 2 falls in the vertical direction by gravity and is formed into a plate shape. Thereby, the glass plate 3 is continuously shape | molded in the vicinity of the lower end 62a of the molded object 62. FIG. The formed glass plate 3 flows down the overflow chamber 60 and then is conveyed downward while being cooled in the forming chamber 70 and the cooling chamber 80. The temperature of the glass plate 3 immediately after being molded in the overflow chamber 60 is 1100 ° C. or higher, and the viscosity is 2.5 × 10 ⁵ poise or higher.

(2-2) Upper Partition Member The upper partition member 64 is a pair of plates with high heat insulation that are installed in the vicinity of the lower end 62 a of the molded body 62. As shown in FIG. 4, the upper partition member 64 is disposed on both sides of the glass plate 3 in the thickness direction. The upper partition member 64 partitions the overflow chamber 60 and the forming chamber 70 and blocks heat transfer from the overflow chamber 60 to the forming chamber 70.

(2-3) Cooling Roll The cooling roll 72 is a cantilever roll installed in the forming chamber 70. The cooling roll 72 is installed directly below the upper partition member 64. As shown in FIG. 3, the cooling rolls 72 are disposed on both sides in the width direction of the glass plate 3. As shown in FIG. 4, the cooling rolls 72 are disposed on both sides of the glass plate 3 in the thickness direction. The cooling roll 72 cools the glass plate 3 sent from the overflow chamber 60.

  In the forming chamber 70, both sides in the width direction of the glass plate 3 are sandwiched between two pairs of cooling rolls 72, respectively. When the cooling roll 72 is pressed toward the surface of the both sides of the glass plate 3, the contact area of the cooling roll 72 and the glass plate 3 goes up, and the cooling of the glass plate 3 by the cooling roll 72 is performed efficiently. The cooling roll 72 gives the glass plate 3 a force that opposes the force with which pulling rolls 82 a to 82 g described later pull the glass plate 3 downward. In addition, the thickness of the glass plate 3 is determined by the difference between the rotation speed of the cooling roll 72 and the rotation speed of the pulling roll 82a disposed at the uppermost position.

The cooling roll 72 has an air cooling tube inside. The cooling roll 72 is always cooled by an air cooling tube. The cooling roll 72 is in contact with the glass plate 3 at both sides in the width direction of the glass plate 3. Thereby, since heat is transmitted from the glass plate 3 to the cooling roll 72, both side portions in the width direction of the glass plate 3 are cooled. The viscosity of both sides in the width direction of the glass plate 3 cooled in contact with the cooling roll 72 is, for example, 10 ^9.0 poise or more.

(2-4) Temperature Control Unit The temperature control unit 74 is installed in the forming chamber 70. The temperature adjustment unit 74 is installed below the upper partition member 64 and above the lower partition member 76.

  In the forming chamber 70, the glass plate 3 is cooled until the temperature of the central portion in the width direction of the glass plate 3 decreases to the vicinity of the annealing point. The temperature adjustment unit 74 adjusts the temperature of the glass plate 3 cooled in the forming chamber 70. The temperature adjustment unit 74 is a unit that heats or cools the glass plate 3. As shown in FIG. 3, the temperature adjustment unit 74 includes a central cooling unit 74a and a side cooling unit 74b. The center cooling unit 74a adjusts the temperature of the center of the glass plate 3 in the width direction. The side cooling unit 74 b adjusts the temperature of both sides in the width direction of the glass plate 3. Here, the center portion in the width direction of the glass plate 3 is a region sandwiched between both side portions in the width direction of the glass plate 3.

  In the forming chamber 70, as shown in FIG. 3, a plurality of center cooling units 74a and a plurality of side cooling units 74b are arranged along the vertical direction, which is the direction in which the glass plate 3 flows down. . The center part cooling unit 74a is disposed so as to face the surface of the center part in the width direction of the glass plate 3. The side cooling unit 74 b is disposed so as to face the surfaces of both side portions in the width direction of the glass plate 3.

  The temperature adjustment unit 74 is controlled by a control device. Each center cooling unit 74a and each side cooling unit 74b can be individually controlled by a control device.

(2-5) Lower Partition Member The lower partition member 76 is a pair of plates with high heat insulation that are installed below the temperature adjustment unit 74. As shown in FIG. 4, the lower partition members 76 are installed on both sides of the glass plate 3 in the thickness direction. The lower partition member 76 partitions the forming chamber 70 and the cooling chamber 80 in the vertical direction and blocks heat transfer from the forming chamber 70 to the cooling chamber 80.

(2-6) Pulling rolls The pulling rolls 82 a to 82 g are cantilever rolls installed in the cooling chamber 80. The pulling rolls 82a to 82g pull the glass plate 3 that has passed through the forming chamber 70 downward in the vertical direction. That is, the pulling rolls 82a to 82g convey the glass plate 3 downward. The pulling rolls 82a to 82g are arranged in the cooling chamber 80 at intervals along the direction in which the glass plate 3 is conveyed. 3 and 4 show seven pulling rolls 82a to 82g. The pulling roll 82a is disposed at the uppermost position, and the pulling roll 82g is disposed at the lowermost position.

  Each of the pulling rolls 82 a to 82 g is composed of two pairs of rolls sandwiching both side portions in the width direction of the glass plate 3, similarly to the cooling roll 72. For example, the pulling rolls 82a are arranged on both sides in the width direction of the glass plate 3 as shown in FIG. 3, and are arranged on both sides in the thickness direction of the glass plate 3 as shown in FIG. . Similarly, each of the other pulling rolls 82b to 82g is disposed on both sides in the width direction of the glass plate 3 and on both sides in the thickness direction of the glass plate 3.

  The pulling rolls 82a to 82g are driven by a motor (not shown). The pulling rolls 82a to 82g are rotationally driven by a motor so that the glass plate 3 is conveyed downward in the vertical direction. Specifically, in FIG. 4, the pulling rolls 82 a to 82 g shown on the left side of the glass plate 3 rotate clockwise, and the pulling rolls 82 a to 82 g shown on the right side of the glass plate 3 rotate counterclockwise. To do.

(2-7) Heater The heaters 84 a to 84 g are installed in the cooling chamber 80. As shown in FIGS. 3 and 4, in the cooling chamber 80, the plurality of heaters 84 a to 84 g are arranged so as to face the surfaces on both sides of the glass plate 3 along the conveyance direction of the glass plate 3. . Each of the heaters 84 a to 84 g is arranged so as to sandwich the glass plate 3 in the thickness direction of the glass plate 3. 7 and 7 show seven heaters 84a to 84g. The heater 84a is disposed at the uppermost position, and the heater 84g is disposed at the lowermost position.

  The heaters 84 a to 84 g are heat supply sources for raising the temperature of the glass plate 3. The heaters 84 a to 84 g radiate heat toward the surface of the opposing glass plate 3 to heat the glass plate 3. The heaters 84 a to 84 g adjust the temperature of the glass plate 3 conveyed downward in the cooling chamber 80. By using the plurality of heaters 84 a to 84 g installed along the conveyance direction of the glass plate 3, a predetermined temperature distribution can be formed on the glass plate 3 in the conveyance direction of the glass plate 3. Further, the heaters 84 a to 84 g have an elongated shape in the width direction of the glass plate 3. Therefore, each heater 84 a to 84 g can form a predetermined temperature distribution on the glass plate 3 in the width direction of the glass plate 3.

  A thermocouple (not shown) for measuring the temperature of the atmosphere of the cooling chamber 80 is installed in the vicinity of each of the heaters 84a to 84g. The thermocouple measures the ambient temperature near the center of the glass plate 3 in the width direction and the ambient temperature near both sides of the glass plate 3 in the width direction. The outputs of the heaters 84a to 84g may be controlled based on the temperature of the atmosphere in the cooling chamber 80 measured by a thermocouple.

  The arrow H shown in FIG. 3 represents the width direction of the glass plate 3, and the arrow V shown in FIG. 3 and FIG. 4 represents the direction in which the glass plate 3 is conveyed. Hereinafter, the direction indicated by the arrow H is referred to as “horizontal direction” and the direction indicated by the arrow V is referred to as “vertical direction” as necessary. The horizontal direction is the longitudinal direction of the heaters 84a to 84g.

  FIG. 5 illustrates the configuration of the heaters 84a to 84g when the heaters 84a to 84g are viewed along a direction perpendicular to the surface of the glass plate 3. In FIG. 5, the heaters 84a to 84g are drawn so as to be close to each other in the vertical direction. FIG. 5 shows a center line C indicating the center of the heater 84a in the horizontal direction. As shown in FIG. 5, the heaters 84 a to 84 g are each divided into a plurality of divided heaters 85 a 1 to 85 a 5, 85 b 1 to 85 b 5,. For example, the heater 84a is divided into five divided heaters 85a1 to 85a5 along the horizontal direction. The divided heaters 85a1 to 85a5,... Are heating wires such as chromium-based heating wires. The outputs of the divided heaters 85a1 to 85a5,... Can be individually controlled by the control device.

  The detailed configuration of the heaters 84a to 84g will be described by taking the heater 84a as an example. The heater 84a includes five divided heaters 85a1 to 85a5. In FIG. 5, a divided heater 85a1, a divided heater 85a2, a divided heater 85a3, a divided heater 85a4, and a divided heater 85a5 are arranged from left to right. The divided heater 85a1 is disposed on the leftmost side in the horizontal direction. The divided heater 85a5 is disposed on the rightmost side in the horizontal direction. The divided heaters 85a1 and 85a5 heat both ends of the glass plate 3 in the horizontal direction. The divided heater 85a3 heats the central portion of the glass plate 3 in the horizontal direction. A gap is formed along the vertical direction between the divided heaters 85a1 to 85a5 that are adjacent to each other in the horizontal direction. The surface of the glass plate 3 that faces the “heater gap”, which is a gap between the divided heaters 85a1 to 85a5, is a region that is unlikely to receive heat radiated from the heater 85a directly. The divided heater 85a3 has a symmetrical shape with respect to the center line C. The divided heater 85a1 has a shape symmetrical to the divided heater 85a5 with respect to the center line C, and the divided heater 85a2 has a shape symmetrical to the divided heater 85a4 with respect to the center line C. The above description is applicable to the other heaters 85b to 85g. For example, the heater 85b includes five divided heaters 85b1 to 85b5, and the divided heaters 85b1 and 85b5 heat both ends of the glass plate 3 in the horizontal direction.

  As shown in FIG. 5, with respect to some of the heaters 84a to 84g, the heater gap positions of the heaters 84a to 84g may differ between the heaters 84a to 84g adjacent in the vertical direction. That is, the positions of the heater gaps of the heaters 84a to 84g are not all the same. Specifically, the horizontal dimension of each of the divided heaters 85a1 to 85a5,... Varies depending on the heaters 84a to 84g to which the divided heaters 85a1 to 85a5,. Hereinafter, the horizontal dimension of the divided heaters 85a1 to 85a5,... Is simply referred to as the “width” of the divided heaters 85a1 to 85a5,. For example, the widths of the divided heaters 85a1 to 85a5 of the heater 84a are different from the widths of the divided heaters 85b1 to 85b5 of the heater 84b, respectively. Specifically, as shown in FIG. 5, the width of the divided heater 85a1 is smaller than the width of the divided heater 85b1, and the width of the divided heater 85a3 is larger than the width of the divided heater 85b3. Similarly, the widths of the divided heaters 85c1 to 85c5 of the heater 84c are different from the widths of the divided heaters 85d1 to 85d5 of the heater 84d, respectively, and the widths of the divided heaters 85e1 to 85e5 of the heater 84e are respectively divided of the heater 84f. It differs from the width of the heaters 85f1 to 85f5.

  Therefore, some of the divided heaters 85a1 to 85a5,... Are adjacent to the plurality of divided heaters 85a1 to 85a5,. For example, the divided heater 85b1 is adjacent to the divided heater 85a1 and the divided heater 85a2. The divided heater 85a2 is adjacent to the divided heater 85b1 and the divided heater 85b2. The divided heater 85a3 is adjacent to the divided heater 85b2, the divided heater 85b3, and the divided heater 85b4. Therefore, as shown in FIG. 5, the divided heaters 85a1 to 85a5 of some of the heaters 84a to 84g are alternately arranged along the vertical direction.

  On the other hand, as shown in FIG. 5, the heater gap positions of the heaters 84a to 84g may be equal between the heaters 84a to 84g adjacent in the vertical direction. For example, the widths of the divided heaters 85b1 to 85b5 of the heater 84b are the same as the widths of the divided heaters 85c1 to 85c5 of the heater 84c, respectively. Similarly, the widths of the divided heaters 85d1 to 85d5 of the heater 84d are the same as the widths of the divided heaters 85e1 to 85e5 of the heater 84e, and the widths of the divided heaters 85f1 to 85f5 of the heater 84f are respectively the heater 84g. The divided heaters 85g1 to 85g5 have the same width.

  FIG. 6 is an output table of the divided heaters 85a1 to 85a5,. In FIG. 6, the outputs of the divided heaters 85a1 to 85a5,... Are expressed as electric energy per unit length of the divided heaters 85a1 to 85a5,. In FIG. 6, the unit of electric energy is kWh. 6, the cell widths of the divided heaters 85a1 to 85a5,... Correspond to the widths of the divided heaters 85a1 to 85a5,. For example, since the width of the divided heater 85a1 is smaller than the width of the divided heater 85b1, the width of the cell of the divided heater 85a1 is smaller than the width of the cell of the divided heater 85b1. Further, since the width of the divided heater 85a3 is larger than the width of the divided heater 85b3, the width of the cell of the divided heater 85a3 is larger than the width of the cell of the divided heater 85b3.

  The upper table of FIG. 7 is a table of the cells of the divided heaters 85a1 to 85a5 of the heater 84a and the cells of the divided heaters 85b1 to 85b5 of the heater 84b shown in FIG. In FIG. 7, the number of sets of divided heaters 85 a 1 to 85 a 5 and divided heaters 85 b 1 to 85 b 5 that are adjacent in the vertical direction is nine. As shown in FIGS. 6 and 7, these nine sets are divided into a heater pair 85ab1 that is a set of the divided heater 85a1 and the divided heater 85b1, a heater pair 85ab2 that is a set of the divided heater 85a2 and the divided heater 85b1, A heater pair 85ab3 that is a set of the heater 85a2 and the divided heater 85b2, a heater pair 85ab4 that is a set of the divided heater 85a3 and the divided heater 85b2, a heater pair 85ab5 that is a set of the divided heater 85a3 and the divided heater 85b3, and a divided heater 85a3 Heater pair 85ab6, which is a set of divided heater 85b4, heater pair 85ab7 which is a set of divided heater 85a4 and divided heater 85b4, heater pair 85ab8 which is a set of divided heater 85a4 and divided heater 85b5, and divided heater 85a5 And a divided heater 85b5 It is over data versus 85ab9. These nine heater pairs 85ab1-85ab9 are arranged along the horizontal direction and are regarded as individually controllable units. For example, when the heater 84b and the heater 84c are considered as one heater, the outputs of the nine heater pairs 85ab1 to 85ab9 are individually controlled by individually controlling the outputs of the divided heaters 85b1 to 85b5 and 85c1 to 85c5. can do. The lower table in FIG. 7 is an output table of nine heater pairs 85ab1 to 85ab9 configured from the divided heaters 85a1 to 85a5 and 85b1 to 85b5. The outputs of the heater pairs 85ab1 to 85ab9 are the sum of the outputs of the two divided heaters 85a1 to 85a5 and 85b1 to 85b5 that constitute each of the heater pairs 85ab1 to 85ab9. For example, the output of the heater pair 85ab1 is the sum of the output of the divided heater 85a1 and the output of the divided heater 85b1.

  The above description is applicable to other divided heaters 85a1 to 85a5,... Arranged alternately along the vertical direction. FIG. 8 is a table similar to FIG. 7, and is a table of outputs of the divided heaters 85c1 to 85c5 and the divided heaters 85d1 to 85d5, and outputs of nine heater pairs 85cd1 to 85cd9. The heater pairs 85cd1 to 85cd9 are a set of any one of the divided heaters 85c1 to 85c5 and any one of the divided heaters 85d1 to 85d5 which are adjacent in the vertical direction. FIG. 9 is a table similar to FIG. 7, and is a table of outputs of the divided heaters 85e1 to 85e5 and the divided heaters 85f1 to 85f5 and outputs of the nine heater pairs 85ef1 to 85ef9. The heater pairs 85ef1 to 85ef9 are a set of any one of the divided heaters 85e1 to 85e5 and any one of the divided heaters 85f1 to 85f5 that are adjacent in the vertical direction.

  The heaters 84a to 84g can form a predetermined temperature distribution along the width direction of the glass plate 3 on the surface of the glass plate 3 facing the heaters 84a to 84g. In the cooling chamber 80, the glass plate 3 is cooled while a predetermined temperature distribution is formed in the width direction thereof, so that the glass plate 3 transitions from the viscous region to the elastic region through the viscoelastic region. Thus, in the cooling chamber 80, the temperature of the center part in the width direction of the glass plate 3 is gradually cooled from the vicinity of the annealing point to the vicinity of a temperature 200 ° C. lower than the strain point.

  The space in which the heaters 84a to 84c are arranged is a first slow cooling space in which the temperature of the central portion in the width direction of the glass plate 3 is gradually cooled from the vicinity of the slow cooling point to the vicinity of the strain point. The space in which the heaters 84d to 84g are arranged is a second slow cooling space in which the temperature of the central portion in the width direction of the glass plate 3 is gradually cooled from the vicinity of the strain point to a temperature near 200 ° C. below the strain point. .

  In this embodiment, the divided heaters 85a1 to 85a5,..., 85c1 to 85c5 of the heaters 84a to 84c installed in the first slow cooling space are alternately arranged along the vertical direction in at least one place. Yes. Moreover, the divided heaters 85d1 to 85d5,..., 85g1 to 85g5 of the heaters 84d to 84g installed in the second slow cooling space are alternately arranged along the vertical direction in at least one place.

(2-8) Heat Insulating Plates The heat insulating plates 86a to 86g are heat insulating plates installed between the two heaters 84a to 84g adjacent in the conveying direction of the glass plate 3. 3 and 4 show seven heat insulating plates 86a to 86g. The heat insulating plate 86a is disposed at the uppermost position, and the heat insulating plate 86g is disposed at the lowermost position.

  The heat insulating plates 86a to 86g suppress the movement of heat between the two spaces where the two heaters 84a to 84g adjacent in the conveying direction of the glass plate 3 are respectively installed. For example, the heat insulating plate 86a partitions the space in which the heater 84a is installed from the space in which the heater 84b is installed, and suppresses the movement of heat between these spaces.

  Further, the heat insulating plate 86 a is installed at a position as close as possible to the surface of the glass plate 3. That is, the heat insulating plate 86a has a shape that does not come into contact with the surface of the glass plate 3, and heat transfer between the space above the heat insulating plate 86a and the space below the heat insulating plate 86a is suppressed as much as possible. It has such a shape.

(2-9) Control Device The control device is mainly composed of a CPU, RAM, ROM, hard disk, and the like. The control device is connected to the cooling roll 72, the temperature adjustment unit 74, the pulling rolls 82a to 82g, the heaters 84a to 84g, and the like. The control device can control these components included in the molding device 40. Specifically, the control device can control the rotation speed of the cooling roll 72 and the pulling rolls 82a to 82g, the output of the temperature adjustment unit 74, and the outputs of the heaters 84a to 84g.

(3) Operation of the forming apparatus In the overflow chamber 60, the molten glass 2 sent from the stirring device 30 to the forming apparatus 40 via the transfer pipe 50c is supplied to the groove 62b formed on the upper surface of the formed body 62. . The molten glass 2 overflowed from the groove 62 b of the molded body 62 flows down along both side surfaces of the molded body 62 and merges in the vicinity of the lower end 62 a of the molded body 62. The joined molten glass 2 is formed into a plate shape. Thereby, the glass plate 3 is continuously shape | molded in the vicinity of the lower end 62a of the molded object 62. FIG. The formed glass plate 3 flows down by gravity and is sent to the forming chamber 70.

  In the forming chamber 70, both side portions of the glass plate 3 in the width direction are brought into contact with the cooling roll 72 and rapidly cooled. The temperature of the glass plate 3 is adjusted by the temperature adjusting unit 74 until the temperature of the central portion in the width direction of the glass plate 3 is lowered to the annealing point. The glass plate 3 cooled while being conveyed downward by the cooling roll 72 is sent to the cooling chamber 80.

  In the cooling chamber 80, the glass plate 3 is gradually cooled while being pulled down by the plurality of pulling rolls 82a to 82g. The temperature of the glass plate 3 is adjusted by the heaters 84 a to 84 g so that a predetermined temperature distribution is formed in the width direction of the glass plate 3. In the cooling chamber 80, the temperature of the glass plate 3 gradually decreases from the vicinity of the annealing point to a temperature 200 ° C. lower than the strain point. The glass plate 3 that has passed through the cooling chamber 80 and is further cooled to near room temperature is cut into a predetermined size, and polishing and cleaning of the end face are performed. Thereafter, the glass plate 3 that has passed the predetermined inspection is packed and shipped as a product.

  As shown in FIG. 5, the heater 84 a is divided into five divided heaters 85 a 1 to 85 a 5 in the width direction of the glass plate 3. The outputs of the divided heaters 85a1 to 85a5 are controlled so that the output of the divided heater 85a3 at the center in the width direction of the glass plate 3 is larger than the outputs of the divided heaters 85a1 and 85a5 at both ends. Thereby, the surface of the glass plate 3 facing the heater 84 a has a temperature distribution in which the central portion is convex in the width direction of the glass plate 3. The surface of the glass plate 3 facing the other heaters 84b to 84g also has a temperature distribution in which the central portion is convex in the width direction of the glass plate 3 by the same method.

  In addition, the surface of the glass plate 3 facing some of the heaters 84 a to 84 g may have a temperature distribution in which the central portion is concave in the width direction of the glass plate 3. For example, as the glass plate 3 is conveyed downward in the cooling chamber 80, the temperature distribution on the surface of the glass plate 3 facing each of the heaters 84 a to 84 g changes from a shape in which the central portion is convex, so that the central portion is concave. The shape may be gradually changed to the shape.

(4) Features The glass plate manufacturing apparatus 1 includes seven heaters 84 a to 84 g that are installed in the cooling chamber 80 along the conveyance direction (vertical direction) of the glass plate 3. Regarding two heaters 84a and 84b adjacent in the vertical direction, some of the divided heaters 85a1 to 85a5 of one heater 84a are adjacent to the plurality of divided heaters 85b1 to 85b5 of the other heater 84b in the vertical direction. For example, the divided heater 85b1 is adjacent to the divided heater 85a1 and the divided heater 85a2. Therefore, the heater gap between the divided heater 85a1 and the divided heater 85a2 is adjacent to the divided heater 85b1 in the vertical direction. As described above, the divided heaters 85a1 to 85a5 and 85b1 to 85b5 of the heaters 84a and 84b are alternately arranged along the vertical direction. And by arrange | positioning the division | segmentation heater 85a1-85a5, 85b1-85b5 alternately, and controlling the output of division | segmentation heater 85a1-85a5, 85b1-85b5 separately, as FIG. The outputs of the nine heater pairs 85ab1 to 85ab9 arranged along the width direction (horizontal direction) can be individually controlled. The nine heater pairs 85ab1 to 85ab9 are a set of any one of the divided heaters 85a1 to 85a5 and any one of the divided heaters 85b1 to 85b5 that are adjacent in the vertical direction. The outputs of the heater pairs 85ab1 to 85ab9 are the total outputs of the two divided heaters 85a1 to 85a5 and 85b1 to 85b5 that constitute the heater pairs 85ab1 to 85ab9.

  As described above, with respect to the heaters 84a and 84b adjacent in the vertical direction, the outputs of the divided heaters 85a1 to 85a5 and 85b1 to 85b5 are individually controlled, so that the nine heaters 84a and 84b are arranged along the horizontal direction. The outputs of the heater pairs 85ab1 to 85ab9 can be individually controlled. Accordingly, nine temperature controllable regions corresponding to the nine heater pairs 85ab1 to 85ab9 can be formed along the horizontal direction on the surface of the glass plate 3 facing the heaters 84a and 84b. Therefore, it is not necessary to use a heater divided into nine parts along the horizontal direction instead of the heaters 84a and 84b.

  Thus, in the glass plate manufacturing apparatus 1, nine temperature control is possible on the surface of the glass plate 3 along the horizontal direction by arranging the divided heaters 85a1 to 85a5 and 85b1 to 85b5 alternately along the vertical direction. Can be formed. As the number of temperature controllable regions formed on the surface of the glass plate 3 is larger, the temperature of the surface of the glass plate 3 can be controlled in a more complicated and higher degree of freedom along the horizontal direction. it can. The above description is based on the heater pairs 85cd1 to 85cd9 composed of the divided heaters 85c1 to 85c5 and 85d1 to 85d5 of the heaters 84c and 84d, and the heaters composed of the divided heaters 85e1 to 85e5 and 85f1 to 85f5 of the heaters 84e and 84f. It can be applied to the pairs 85ef1 to 85ef9. The heaters 84a to 84g are configured with the number of temperature controllable regions formed on the surface of the glass plate 3 by arranging some of the divided heaters 85a1 to 85a5,... Alternately along the vertical direction. The number of divided heaters 85a1 to 85a5,.

  That is, in the glass plate manufacturing apparatus 1, the divided heaters 85 a 1 to 85 g constituting the heaters 84 a to 84 g are arranged by staggering the divided heaters 85 a 1 to 85 a 5,... Of some of the heaters 84 a to 84 g along the vertical direction. The number of 85a5,... Can be reduced. Thereby, since the number of the division | segmentation heaters 85a1-85a5 ... individually controlled by a control apparatus becomes small, the manufacturing cost of the glass plate manufacturing apparatus 1 is suppressed.

  Moreover, since the number of the divided heaters 85a1 to 85a5,... Constituting the heaters 84a to 84g can be reduced, in each of the heaters 84a to 84g, the divided heaters 85a1 to 85a5,. The number of heater gaps between them can also be reduced. The region that is included on the surface of the glass plate 3 and faces the heater gaps of the heaters 84a to 84g is a region that is not easily heated by the heaters 84a to 84g because it is difficult to directly receive the heat radiated from the heaters 84a to 84g. . Therefore, the temperature distribution in the width direction of the surface of the glass plate 3 shows a tendency for the temperature to locally decrease in a region facing the heater gaps of the heaters 84a to 84g. Therefore, the surface of the glass plate 3 heated by the heaters 84a to 84g has a temperature distribution in which the temperature locally changes in the width direction of the glass plate 3 by reducing the number of heater gaps of the heaters 84a to 84g. It is suppressed. In a region where the temperature of the surface of the glass plate 3 changes locally, internal stress due to a temperature difference from the surroundings tends to occur, and the warp and distortion of the glass plate 3 tend to occur. Therefore, the glass plate manufacturing apparatus 1 suppresses the curvature and distortion of the glass plate 3 by forming a favorable temperature distribution on the glass plate 3 along the width direction of the glass plate 3 using the heaters 84a to 84g. A high quality glass plate 3 can be manufactured.

  FIG. 10 is a graph showing the temperature distribution in the horizontal direction on the surface of the glass plate 3 facing the heater 84c. In the graph of FIG. 10, the horizontal axis represents the horizontal distance from the left end of the glass plate 3, and the vertical axis represents the temperature of the surface of the glass plate 3. As shown in FIG. 10, the horizontal temperature distribution on the surface of the glass plate 3 is unlikely to have a minimum value at which the temperature locally decreases. Next, the reason will be described. As shown in FIG. 5, the heater gaps of the heaters 84a to 84g are adjacent to the divided heaters 85a1 to 85a5,... Of the other heaters 84a to 84g in the vertical direction. For example, the heater gap between the two divided heaters 85a1 and 85a2 of the heater 84a is adjacent to the divided heater 85b1 of the heater 84b in the vertical direction. For this reason, the surface of the glass plate 3 facing the heater gap between the divided heater 85a1 and the divided heater 85a2 of the heater 85a is less susceptible to heat radiated from the heater 84a, but the heater 85b disposed below the heater gap. It is easy to receive the heat radiated from the divided heater 85b1. Therefore, by receiving heat radiated from the heaters 85a and 85b, the horizontal temperature distribution on the surface of the glass plate 3 is unlikely to have a minimum value.

  FIG. 11 is a reference diagram illustrating a configuration of conventional heaters 184a to 184g. FIG. 12 is a graph showing the temperature distribution in the horizontal direction on the surface of the glass plate 3 facing the conventional heater 184a. Each of the heaters 184a to 184g is divided into five divided heaters 185a1 to 185a5,... Along the horizontal direction. Regarding the heaters 184a to 184g, the divided heaters 185a1 to 185a5,... Have the same width. Therefore, for example, as shown in FIG. 11, the heater gap between the divided heater 185a1 and the divided heater 185a2 of the heater 184a is equal to the heater gap between the divided heater 185b1 and the divided heater 185b2 of the heater 184b. Next to each other. Thus, all the heater gaps of the heaters 184a to 184g are adjacent in the vertical direction. And the area | region which is contained in the surface of the glass plate 3, and opposes the heater clearance gap of the heaters 184a-184g is an area | region where temperature falls locally. Therefore, while the glass plate 3 is being conveyed downward through the cooling chamber 80, the temperature is always locally reduced in the horizontal direction corresponding to the region facing the heater gap on the surface of the glass plate 3. A temperature distribution having a region is formed. Therefore, as shown in the graph of FIG. 12, the horizontal temperature distribution on the surface of the glass plate 3 has a shape that greatly decreases locally in the vicinity of the region facing the heater gap of the heater 184a. .

  Moreover, the glass plate manufacturing apparatus 1 is suitable for manufacturing the glass plate 3 by cooling the temperature of the glass plate 3 from the vicinity of the annealing point to the vicinity of the strain point in the cooling chamber 80. Moreover, the glass plate manufacturing apparatus 1 is suitable when manufacturing the glass plate 3 whose strain point is 675 degreeC-725 degreeC.

(5) Modified Example A modified example of the present embodiment will be described with reference to the drawings. The glass plate manufacturing apparatus according to each modification has the same configuration as the glass plate manufacturing apparatus 1 according to the present embodiment, except for the heater. Therefore, the following modifications will be described focusing on the configuration and effects of the heater.

(5-1) Modification A
In the present embodiment, as shown in FIG. 3, a temperature adjustment unit 74 is installed in the forming chamber 70. The temperature adjustment unit 74 includes a center cooling unit 74a and a side cooling unit 74b. The center cooling unit 74a adjusts the temperature of the center of the glass plate 3 in the width direction. The side cooling unit 74 b adjusts the temperature of both sides in the width direction of the glass plate 3.

  As shown in FIG. 3, the temperature adjustment unit 74 includes three cooling units installed along the conveyance direction (vertical direction) of the glass plate 3. Each cooling unit includes one central cooling unit 74a and a pair of side cooling units 74b disposed on both sides of the central cooling unit 74a. Regarding two cooling units adjacent in the vertical direction, the horizontal dimension of the central cooling unit 74a and the horizontal dimension of the side cooling unit 74b are the same. However, similarly to the divided heaters 85a1 to 85a5,... Of the heaters 84a to 84g, the center cooling unit 74a and the side cooling unit 74b of the three cooling units may be alternately arranged along the vertical direction. Good. For example, the side cooling unit 74b of the cooling unit installed at the uppermost position is adjacent to the center cooling unit 74a and the side cooling unit 74b of the cooling unit installed second from the top in the vertical direction. May be.

(5-2) Modification B
In the present embodiment, for example, the heater 84a includes five divided heaters 85a1 to 85a5. However, the heater 84a may be composed of an arbitrary number of divided heaters 85a1, 85a2,. Generally, as the number of the divided heaters 85a1, 85a2,... Included in the heater 84a increases, the surface of the glass plate 3 heated by the heat radiated from the heater 84a becomes more complicated and more flexible. A high horizontal temperature distribution can be formed. As a result, a temperature distribution in the width direction can be formed on the surface of the glass plate 3 with higher accuracy. Similarly, the other heaters 84b to 84g may be composed of an arbitrary number of divided heaters 85b1, 85b2,. The number of heaters 84 a to 84 g installed in the vertical direction in the cooling chamber 80 may be arbitrarily set according to the dimensions of the molding device 40, the composition of the molten glass 2, and the like.

(5-3) Modification C
In the present embodiment, the divided heaters 85a1 to 85a5,... Of the heaters 84a to 84g are, for example, heating wires such as chromium-based heating wires. The heat radiated from each of the divided heaters 85a1 to 85a5,... Transmits the space between the heaters 84a to 84g and the glass plate 3. The surface of the glass plate 3 facing the heaters 84a to 84g is heated by receiving heat from the heaters 84a to 84g.

  However, a soaking plate may be installed in the space between the heaters 84 a to 84 g and the glass plate 3 so as to face the surface of the glass plate 3. The soaking plate receives heat radiated from the heaters 84a to 84g, and diffuses the received heat over the entire surface of the soaking plate. The soaking plate radiates heat from the facing surface toward the surface of the glass plate 3. The soaking plate is composed of one metal plate or a plurality of metal plates. Each of the heaters 84a to 84g radiates heat toward the corresponding heat equalizing plate. For example, the soaking plate corresponding to the heater 84a receives heat radiated from the heater 84a and radiates the received heat toward the surface of the glass plate 3 facing the soaking plate. In the present embodiment, the region that is included on the surface of the glass plate 3 and faces the heater gaps of the heaters 84a to 84g is a region where the temperature locally decreases. The soaking plate diffuses the heat received from the heaters 84 a to 84 g over the entire surface of the soaking plate and radiates it toward the surface of the glass plate 3, thereby locally reducing the temperature of the surface of the glass plate 3. Can be suppressed.

  The soaking plate is preferably a nickel metal plate that can be used at high temperatures and has high thermal conductivity. From the viewpoint of forming a smooth temperature distribution along the width direction of the glass plate 3, the thermal conductivity of the soaking plate is preferably 10 W / (m · K) or more. Further, the soaking plate may be coated with a ceramic coating to form a ceramic layer or an oxide film may be formed on the surface in order to improve the radiation rate of heat from the surface. From the viewpoint of suppressing foreign matters such as dust from adhering to the surface of the glass plate 3, it is preferable that a passive film (super black treatment film) having a thickness of about 1 μm is formed on the surface of the soaking plate.

(5-4) Modification D
In this embodiment, the glass plate 3 is formed from the molten glass 2 by the overflow downdraw method, but the glass plate 3 may be formed from the molten glass 2 by another downdraw method. For example, the glass plate 3 may be formed from the molten glass 2 by a redraw method, a slit down draw method, or the like.

DESCRIPTION OF SYMBOLS 1 Glass plate manufacturing apparatus 2 Molten glass 3 Glass plate 62 Molded body 84a-84g Heater (heating means)
84a heater (first heating means)
84b Heater (second heating means)
85a1 to 85a5 divided heater (first divided heating means)
85b1 to 85b5 divided heater (second divided heating means)

JP 2001-31435 A JP 2007-112665 A

Claims (4)

A molding step of forming a glass plate by letting molten glass flow down from the molded body;
A cooling step of cooling the glass plate while conveying the glass plate formed in the forming step downward;
With
In the cooling step, a plurality of heating means arranged along the conveyance direction in which the glass plate is conveyed radiates heat toward the glass plate, and the temperature distribution in the width direction of the glass plate is changed to the glass. Formed on a plate,
The first heating means that is one of the plurality of heating means is divided into a plurality of first divided heating means along the width direction,
The second heating means that is the heating means adjacent to the first heating means in the transport direction is divided into a plurality of second divided heating means along the width direction,
At least one of the first divided heating means is adjacent to the plurality of second divided heating means in the transport direction,
The number of sets of the first divided heating means and the second divided heating means that can be adjacent in the transport direction is at least the number of the first divided heating means and the number of the second divided heating means. Bigger than one,
Glass plate manufacturing method. The cooling step includes
A first cooling step in which the temperature of the glass plate formed in the forming step is lowered to a slow cooling point;
A second cooling step in which the temperature of the glass plate decreases from the annealing point to the strain point;
A third cooling step in which the temperature of the glass plate is lowered from the strain point to a temperature 200 ° C. lower than the strain point;
Including
In each of the first cooling step, the second cooling step, and the third cooling step, the first heating means and the second heating means form the temperature distribution in the width direction on the glass plate.
The glass plate manufacturing method of Claim 1. In the cooling step, as the glass plate is transported downward, the heating means changes the temperature distribution in the width direction to the glass plate so that the temperature difference of the glass plate in the width direction gradually decreases. Form,
The glass plate manufacturing method of Claim 1 or 2. Overflowing the molten glass from the molded body, and forming a glass plate by fusing the molten glass at the lower end of the molded body,
A cooling unit for cooling the glass plate while conveying the glass plate formed by the forming unit downward;
With
The cooling unit has a plurality of heating means arranged along a conveyance direction in which the glass plate is conveyed,
The heating means radiates heat toward the glass plate to form a temperature distribution in the width direction of the glass plate on the glass plate,
The first heating means that is one of the plurality of heating means is divided into a plurality of first divided heating means along the width direction,
The second heating means that is the heating means adjacent to the first heating means in the transport direction is divided into a plurality of second divided heating means along the width direction,
At least one of the first divided heating means is adjacent to the plurality of second divided heating means in the transport direction,
The number of sets of the first divided heating means and the second divided heating means that can be adjacent in the transport direction is at least the number of the first divided heating means and the number of the second divided heating means. Bigger than one,
Glass plate manufacturing equipment.