JP2014193780A - Glass plate manufacturing method and glass plate manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate manufacturing method and a glass plate manufacturing device that can manufacture a glass plate of high quality.SOLUTION: A glass plate manufacturing method includes a molding process and a cooling process. The molding process is a process of molding a glass plate 3 by making molten glass 2 flow down from a molding 62. The cooling process is a process of cooling the glass plate 3 while conveying the glass plate 3 downward. In the cooling process, a plurality of heaters 84a-84g arranged along the conveying direction of the glass plate 3 radiate heat toward the glass plate 3 so as to give the glass plate 3 a temperature distribution in a width direction of the glass plate 3. The heaters 84a-84g are divided into a plurality of division heaters 85a1-85a5 along the width direction of the glass plate 3. At least one of the division heaters 85a1-85a5 is so shaped as to change in position of adjacency to other division heaters 85a1-85a5 in the conveying direction of the glass plate 3.

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 surface of the glass plate. 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 nonuniform temperature distribution in which the temperature is locally reduced on the surface of the glass plate. And in the area | region where the temperature on the surface of a glass plate changes rapidly like the area | region where the temperature on the surface of a glass plate 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 heating means is divided into a plurality of divided heating means along the width direction of the glass plate. In each of the heating means, at least one of the divided heating means has a shape in which the position adjacent to the other divided heating means in the width direction of the glass plate changes in the conveyance direction of the glass plate.

  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 so as to face the surface of the glass plate and radiates heat toward the surface of the glass plate. The heating means is divided into a plurality of divided heating means in the width direction of the glass plate. In each heating unit, the plurality of divided heating units are installed adjacent to each other. By individually controlling the heat radiated from the plurality of divided heating means, the heating means can form a predetermined temperature distribution on the glass plate in the width direction of the glass plate.

  In this glass plate manufacturing method, in each heating unit, at least one divided heating unit is adjacent to another divided heating unit in a position where the glass plate is transported. For example, the boundary between two divided heating means adjacent in the width direction of the glass plate is a straight line that is inclined with respect to the conveying direction of the glass plate. Thereby, the area | region where temperature is locally low is hard to be formed in a heating means in the width direction of a glass plate. Therefore, it is suppressed that the glass plate heated by the heating means has a temperature distribution in which the temperature rapidly changes in the width direction of the glass plate. At locations where the temperature on the surface of the glass plate changes abruptly, internal stress due to the temperature difference is likely to occur, so that warpage and distortion of the glass plate are likely to occur. Therefore, this glass plate manufacturing method can manufacture a high quality glass plate by the heating means which consists of a some division | segmentation heating means.

  In the glass plate manufacturing method according to the present invention, it is preferable that the divided heating means has a heat radiation member having a facing surface facing the surface of the glass plate. The heat radiation member radiates heat from the facing surface toward the surface of the glass plate.

  In this glass plate manufacturing method, the heat radiating member is formed of a material that easily diffuses heat over the entire surface thereof. The heating means radiates heat toward the glass plate via the heat radiating member. Specifically, heat is radiated from the entire facing surface of the heat radiation member toward the opposing glass plate surface. Therefore, it is suppressed that the partial area | region of the glass plate surface facing a heating means is heated locally. Thereby, it is suppressed that the glass plate heated by a heating means has the temperature distribution from which temperature changes rapidly in the width direction of a glass plate. Therefore, this glass plate manufacturing method can manufacture a high-quality glass plate.

  In the glass plate manufacturing method according to the present invention, in each of the heating means, it is preferable that the heat radiation members are connected to each other via a heat insulating member.

  In this glass plate manufacturing method, heat is hardly transmitted between two heat radiation members adjacent in the width direction of the glass plate by the heat insulating member. Therefore, the heating means can form a predetermined temperature distribution on the glass plate with high accuracy in the width direction of the glass plate.

  In the glass plate manufacturing method according to the present invention, in each of the heating means, at least one heat radiation member has a shape in which the position adjacent to the other heat radiation member in the width direction of the glass plate changes in the conveyance direction of the glass plate. It is preferable to have.

  In this glass plate manufacturing method, for example, the boundary between two heat radiation members adjacent in the width direction of the glass plate is a straight line that is inclined with respect to the conveyance direction of the glass plate. Thereby, it is suppressed that the glass plate which opposes a heating means has the temperature distribution from which temperature changes rapidly in the width direction of a glass plate.

  In the glass plate manufacturing method according to the present invention, the number of divided heating means is preferably equal to the number of heat radiation members in each of the heating means.

  In this glass plate manufacturing method, in each heating means, it is more preferable that the heat radiation member corresponds to the divided heating means on a one-to-one basis. In this case, since the heat radiation member is mainly heated by the corresponding divided heating means, the temperature of the heat radiation member can be adjusted with high accuracy.

  In the glass plate manufacturing method according to the present invention, the cooling step may be performed when the maximum value of the glass plate temperature in the width direction is between the vicinity of the annealing point of the glass plate and the vicinity of the strain point. preferable.

  In the glass plate manufacturing method according to the present invention, the strain point of the glass plate is preferably 675 ° C to 725 ° C.

  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 heating means is divided into a plurality of divided heating means along the width direction of the glass plate. In each of the heating means, at least one of the divided heating means has a shape in which the position adjacent to the other divided heating means in the width direction of the glass plate changes in the conveyance direction of the glass plate.

  The glass plate manufacturing method and the glass plate manufacturing apparatus according to the present invention can manufacture a high-quality glass plate by a heating unit that is divided into a plurality of divided heating units along the width direction of the glass plate. .

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 which concerns on embodiment. It is a side view of the shaping | molding apparatus which concerns on embodiment. It is a schematic diagram of the heater which concerns on embodiment. It is a top view of the heat equalizing plate which concerns on embodiment. It is a graph showing the temperature distribution of the vertical direction of a soaking plate. It is a graph showing the temperature distribution of the vertical direction of a soaking plate. It is a graph showing the thermal energy distribution of the horizontal direction of a soaking plate. 10 is a plan view of a heat equalizing plate according to Modification A. FIG. It is a top view of the connection part of the division | segmentation heat equalization board which concerns on the modification A. 10 is a side view of a heat equalizing plate according to Modification A. FIG. 10 is a plan view of a heat equalizing plate according to Modification B. FIG. It is a schematic diagram of the conventional heater as a comparative example. It is a graph showing the thermal energy distribution of the horizontal direction of the conventional soaking plate as a comparative 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. In the cooling chamber 80, a plurality of heaters 84 a to 84 g are arranged on both sides of the glass plate 3 along the conveyance 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 radiate heat toward the surfaces on both sides of the 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. The heaters 84a to 84g may be controlled based on the temperature of the atmosphere of the cooling chamber 80 measured by a thermocouple.

  As shown in FIG. 4, each of the heaters 84a to 84g includes a heat source 91a to 91g and a soaking plate 92a to 92g. For example, the heater 84a includes a heat source 91a and a soaking plate 92a. The soaking plate 92 a is located between the heat source 91 a and the glass plate 3. The same applies to the other heaters 84b to 84g.

  The heat sources 91a to 91g are sources of heat radiated from the heaters 84a to 84g to the glass plate 3. The soaking plates 92 a to 92 g are plates having opposing surfaces that face the surface of the glass plate 3. Next, the heat source 91a and the soaking plate 92a of the heater 84a will be described. The following description is applicable to the other heaters 84b to 84g.

(2-7-1) Heat Source FIG. 5 is a three-dimensional schematic diagram of the heater 84a. FIG. 6 is a plan view of the soaking plate 92a of the heater 84a. The arrow H shown in FIGS. 5 and 6 represents the width direction of the glass plate 3, and the arrow V shown in FIGS. 5 and 6 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 heater 84a, the heat source 91a, and the soaking plate 92a.

  As shown in FIG. 5, the heat source 91a is divided into a plurality of divided heat sources 93a1 to 93a5 along the horizontal direction. In the present embodiment, the heat source 91a includes five divided heat sources 93a1 to 93a5. FIG. 5 shows the divided heat sources 93a1 to 93a5 in order from the left side to the right side. As the divided heat sources 93a1 to 93a5, for example, heating wires such as chromium-based heating wires are used. The outputs of the divided heat sources 93a1 to 93a5 can be individually controlled by the control device.

(2-7-2) Soaking Plate The soaking plate 92a receives the heat radiated from the heat source 91a and diffuses the received heat over the entire surface of the soaking plate 92a. The soaking plate 92 a radiates heat from the facing surface toward the surface of the glass plate 3. As shown in FIG. 6, the soaking plate 92a is divided into a plurality of split soaking plates 94a1 to 94a5 along the horizontal direction. In the present embodiment, the soaking plate 92a is composed of five divided soaking plates 94a1 to 94a5. The divided soaking plates 94a1 to 94a5 are adjacent to each other. In FIG. 6, the divided soaking plates 94a1 to 94a5 are sequentially shown from the left side to the right side, and the center line C in the horizontal direction of the soaking plate 92a is shown. The central divided heat equalizing plate 94a3 has a symmetrical shape with respect to the center line C. Further, the divided soaking plate 94a1 has a shape symmetrical to the divided soaking plate 94a5 with respect to the center line C, and the divided soaking plate 94a2 is symmetrical to the divided soaking plate 94a4 with respect to the center line C. Have a different shape.

  The divided soaking plates 94a1 to 94a5 correspond to the divided heat sources 93a1 to 93a5 on a one-to-one basis. For example, the divided soaking plate 94a1 corresponds to the divided heat source 93a1. That is, the divided heat equalizing plate 94a1 mainly receives heat from the corresponding divided heat source 93a1 and radiates the received heat toward the surface of the opposing glass plate 3. Hereinafter, a set of the divided heat equalizing plate 94a1 and the corresponding divided heat source 93a1 is referred to as a divided heater 85a1 for convenience. Similarly, the sets of the divided heat equalizing plates 94a2 to 94a5 and the corresponding divided heat sources 93a2 to 93a5 are referred to as divided heaters 85a2 to 85a5, respectively. That is, the heater 84a includes five divided heaters 85a1 to 85a5.

  As shown in FIG. 6, the boundaries between the two divided heat equalizing plates 94a1 to 94a5 adjacent in the horizontal direction are straight lines that are inclined with respect to the vertical direction. In FIG. 6, boundaries B1 to B4 are shown from the left side to the right side. For example, the boundary B1 indicates the boundary between the divided soaking plate 94a1 and the divided soaking plate 94a2, and the boundary B4 indicates the boundary between the split soaking plate 94a4 and the split soaking plate 94a5. The boundaries B1 to B4 are straight lines that are inclined downward in the vertical direction indicated by the arrow V in FIG. Specifically, as shown in FIG. 6, the boundaries B1 and B2 are inclined to the transport direction of the glass plate 3 toward the right side in the horizontal direction, and the boundaries B3 and B4 are on the left side in the horizontal direction. As it goes to, it inclines so that it may go to the conveyance direction of the glass plate 3. FIG.

  As shown in FIG. 6, the entire heat equalizing plate 92a has a rectangular shape elongated in the horizontal direction, and the boundaries B1 to B4 are straight lines inclined with respect to the vertical direction. Therefore, each of the divided heat equalizing plates 94a1 to 94a5 has a trapezoidal shape. The horizontal dimension of the divided heat sources 93a1 to 93a5 may be set to an average value of the upper side and the lower side of the trapezoid of the corresponding divided heat equalizing plates 94a1 to 94a5.

  As shown in FIG. 5, the heater 84a is divided into five divided heaters 85a1 to 85a5 in the horizontal direction. Each of the divided heaters 85a1 to 85a5 can be controlled independently by a control device. That is, the temperature of the five divided heat equalizing plates 94a1 to 94a5 constituting the heat equalizing plate 92a can be individually adjusted. Thereby, the heater 84a 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 soaking plate 92a. Similarly, the other heaters 84 b to 84 g can also form a predetermined temperature distribution along the width direction of the glass plate 3 on the surface of the opposing glass plate 3. 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 soaking plate 92a is preferably a nickel metal plate that can be used at high temperatures and has high thermal conductivity, for example. From the viewpoint of forming a smooth temperature distribution along the width direction of the glass plate 3, it is preferable that the thermal conductivity of the soaking plate 92a is 10 W / (m · K) or more. Moreover, in order to improve the heat radiation rate from the surface, the soaking plate 92a may apply | coat a ceramic coating material and may form a ceramic layer, and an oxide film may be formed in the surface. From the viewpoint of suppressing adhesion of foreign substances such as dust 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 92a.

(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 to each other along 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 to each other along the conveying direction of the glass plate 3 are 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 heat sources 91a to 91g 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.

  In the present embodiment, the soaking plate 92a of the heater 84a is divided into five divided soaking plates 94a1 to 94a5 in the width direction of the glass plate 3, as shown in FIG. The heat source 91a of the heater 84a heats the heat equalizing plate 92a so that the temperature of the central divided heat equalizing plate 94a3 is higher than the temperatures of the divided heat equalizing plates 94a1 and 94a5 at both ends. Specifically, regarding the five divided heat sources 93a1 to 93a5 constituting the heat source 91a, the output of the central divided heat source 93a3 is made higher than the outputs of the divided heat sources 93a1 and 93a5 at both ends. Thereby, the soaking plate 92a has a temperature distribution in which the center is convex in the horizontal direction. The temperature distribution in the horizontal direction is also controlled for the other soaking plates 92b to 92g in the same manner.

  The soaking plates 92a to 92g may have a temperature distribution in which the center is concave in the horizontal direction. For example, in the cooling chamber 80, the temperature distribution in the horizontal direction of each of the soaking plates 92a to 92g is changed from a shape having a convex center to a shape having a concave center as it goes in the conveying direction of the glass plate 3. It may change gradually.

(4) Features (4-1)
In the cooling chamber 80, the surface of the glass plate 3 is heated by receiving heat radiated from the heaters 84a to 84g. The heaters 84a to 84g include soaking plates 92a to 92g having opposing surfaces that radiate heat toward the surface of the glass plate 3, respectively. Next, the characteristics of the soaking plate 92a of the heater 84a will be described.

  FIG. 7 is a graph showing the temperature distribution of the soaking plate 92a on the vertical line segment L1 shown in FIG. FIG. 8 is a graph showing the temperature distribution of the soaking plate 92a on the vertical line segment L2 shown in FIG. 7 and 8, the horizontal axis represents the distance from the upper end of the soaking plate 92a in the vertical direction, and the vertical axis represents the temperature of the soaking plate 92a.

  In the divided heat equalizing plates 94a1 to 94a5 constituting the heat equalizing plate 92a, the temperature of the peripheral portion is lower than the temperature of the central portion. Therefore, as shown in FIG. 7, the temperature distribution on the line segment L1 passing through the divided heat equalizing plate 94a1 shows a shape having one convex portion. On the other hand, as shown in FIG. 8, the temperature distribution on the line segment L2 passing through the two divided heat equalizing plates 94a1 and 94a2 has a low temperature in the vicinity of the boundary B1. This is because the boundaries B1 to B4 are portions where the peripheral edges of the divided heat equalizing plates 94a1 to 94a5 are in contact with each other, and the temperature in the vicinity of the boundaries B1 to B4 is lower than the surrounding temperature. Therefore, as shown in FIG. 8, the temperature distribution on the line segment L2 shows a shape having two convex portions corresponding to the temperature distributions of the divided soaking plate 94a1 and the divided soaking plate 94a2.

The energy of electromagnetic waves emitted from the surface of an object per unit area and unit time is expressed by the Stefan-Boltzmann law. This law is expressed as I = εσT ^{4 with} respect to the absolute temperature T (K) of the object surface, the emissivity ε of the object surface, the Boltzmann constant σ (JK ⁻¹ ), and the energy I (J) emitted from the object surface. expressed. The total heat energy released on the line segment L1 and the line segment L2 of the soaking plate 92a is expressed in the temperature distribution line based on Stefan-Boltzmann's law I = εσT ⁴ in the graphs of FIGS. It is obtained by converting to a distribution line and calculating the integrated value for the entire range on the horizontal axis. FIG. 9 is a graph showing the distribution of thermal energy with respect to the position in the longitudinal direction (horizontal direction) of the soaking plate 92a. In the graph of FIG. 9, the horizontal axis represents the distance from the horizontal left end of the soaking plate 92a, and the vertical axis represents the heat energy of the soaking plate 92a. As shown in FIG. 9, the thermal energy distribution line has a shape showing a minimum value of thermal energy in the vicinity of the region where the boundaries B1 to B4 exist.

  In the soaking plate 92a, boundaries B1 to B4 of two divided soaking plates 94a1 to 94a5 adjacent in the horizontal direction are inclined with respect to the conveying direction (vertical direction) of the glass plate 3 and are straight. Here, FIGS. 14 and 15 will be described as a comparative example with the present embodiment. FIG. 14 is a three-dimensional schematic diagram of a conventional heater 984a. FIG. 15 is a graph showing the thermal energy distribution in the horizontal direction of the soaking plate 992a of the heater 984a. The heater 984a corresponds to the heater 84a of the present embodiment.

  The heater 984a includes a heat source 991a and a soaking plate 992a. The soaking plate 992a is composed of a single plate elongated in the horizontal direction. As shown in FIG. 14, the heat source 991a for heating the soaking plate 992a is divided into five divided heat sources 993a1 to 993a5 along the horizontal direction. A heating wire is used as the divided heat sources 993a1 to 993a5. Between the two divided heat sources 993a1 to 993a5 adjacent in the horizontal direction is a region where there is no heating wire. Therefore, in the temperature distribution in the horizontal direction of the heat source 991a, a region between the divided heat sources 993a1 to 993a5 is a region where the temperature is locally low.

  When the thermal conductivity of the soaking plate 992a heated by the heat source 991a is too low, the heat supplied from the heat source 991a is difficult to diffuse over the entire surface of the soaking plate 992a. Therefore, the temperature distribution formed on the heat source 991a can be formed on the soaking plate 992a, and the temperature distribution formed on the soaking plate 992a can be formed on the glass plate 3. However, due to the drop in temperature that occurs between two adjacent heat sources 993a1 to 993a5, a temperature distribution having a region where the temperature is locally low is formed in the heat source 991a. This temperature distribution formed in the heat source 991a may also be formed in the soaking plate 992a. As a result, as shown in FIG. 15, locally uneven heat energy distribution in the horizontal direction may be formed on the surface of the glass plate 3 facing the soaking plate 992a.

  On the other hand, when the thermal conductivity of the soaking plate 992a is too high, the heat supplied from the heat source 991a is likely to diffuse over the entire surface of the soaking plate 992a, which is a single plate. Is difficult to form on the soaking plate 992a. Therefore, it is difficult to form a predetermined temperature distribution with high accuracy in the horizontal direction on the surface of the glass plate 3 facing the soaking plate 992a.

  In the present embodiment, the soaking plate 92a is divided into five divided soaking plates 94a1 to 94a5 in the horizontal direction. Each of the divided soaking plates 94a1 to 94a5 mainly receives heat released from the corresponding divided heat sources 93a1 to 93a5. Each of the divided soaking plates 94a1 to 94a5 is formed of a material having a high thermal conductivity such as nickel and is smaller than the entire soaking plate 92a, and therefore the heat received by each of the divided soaking plates 94a1 to 94a5. Is easily diffused over the entire surface of each of the divided soaking plates 94a1 to 94a5. Therefore, each temperature of the division | segmentation soaking | uniform-heating board 94a1-94a5 is easy to be equalize | homogenized. On the other hand, considering the entire heat equalizing plate 92a, the output of each of the divided heat sources 93a1 to 93a5 is individually controlled, and the temperature of each of the divided heat equalizing plates 94a1 to 94a5 is individually adjusted, so that a predetermined value is set in the horizontal direction. The temperature distribution can be formed on the soaking plate 92a. Further, the boundaries B1 to B4 between the two divided heat equalizing plates 94a1 to 94a5 adjacent to each other in the heat equalizing plate 92a are not along the vertical direction. Therefore, the predetermined region on the surface of the glass plate 3 does not always face the boundaries B1 to B4 while flowing down while facing the soaking plate 92a. That is, all the regions of the surface of the glass plate 3 that flows down while facing the soaking plate 92a can face any one of the divided soaking plates 94a1 to 94a5. Thereby, since the specific area | region of the surface of the glass plate 3 does not oppose the division | segmentation soaking | uniform-heating board 94a1-94a5, it is prevented that it is not fully heated.

  As a result, the temperature distribution in which the temperature locally decreases in the horizontal direction is suppressed from being formed on the glass plate 3 that receives the heat radiated from the soaking plate 92a. And in the location where the temperature on the surface of the glass plate 3 changes rapidly, the internal stress resulting from a temperature difference tends to arise, and the curvature and distortion of the glass plate 3 are easy to generate | occur | produce. In this embodiment, since the rapid temperature change in the horizontal direction of the glass plate 3 heated by the soaking plate 92a is suppressed, the curvature and distortion of the glass plate 3 are reduced. Therefore, the glass plate manufacturing apparatus 1 can manufacture a high-quality glass plate by using the heat equalizing plate 92a including the plurality of divided heat equalizing plates 94a1 to 94a5.

  9 and 15, the method described below may be used to determine the magnitude of the undulation of the thermal energy distribution in the horizontal direction. As an example, in FIG. 9, the magnitude of the undulation of the thermal energy distribution in the region where the boundary B1 exists is calculated. First, a common tangent line T1 in contact with the two convex portions E2 and E3 located on both sides of the concave portion E1 of the thermal energy distribution shown in FIG. 9 is drawn. Next, a tangent line T2 that is parallel to the tangent line T1 and that is in contact with the recess E1 is drawn. Next, a distance D between two parallel tangent lines T1 and T2 is calculated. And let the calculated distance D be the magnitude | size of the undulation of the thermal energy distribution between the two convex parts E2 and E3. As the undulation of the thermal energy distribution is smaller, the rapid temperature change of the soaking plate in the horizontal direction is further suppressed, so that the warp and distortion of the glass plate 3 are less likely to occur.

(4-2)
The heaters 84a to 84g include soaking plates 92a to 92g having opposing surfaces that face the surface of the glass plate 3, respectively. The soaking plates 92a to 92g are formed of a material that easily diffuses heat over the entire surface. Each of the soaking plates 92 a to 92 g radiates heat from the entire facing surface toward the surface of the glass plate 3. Therefore, the horizontal temperature distribution formed on the surface of the glass plate 3 facing the soaking plates 92a to 92g is affected by the horizontal temperature distribution formed on the soaking plates 92a to 92g. For example, when the horizontal temperature distribution formed on the soaking plate 92a of the heater 84a has a convex shape at the center, the horizontal direction formed on the surface of the glass plate 3 facing the soaking plate 92a. The temperature distribution also has a shape with a convex center.

  Thereby, the glass plate manufacturing apparatus 1 forms a predetermined horizontal temperature distribution on the soaking plates 92a to 92g of the heaters 84a to 84g, so that the surface of the glass plate 3 facing the soaking plates 92a to 92g is formed. Also, a horizontal temperature distribution having a similar shape can be formed. Therefore, the glass plate manufacturing apparatus 1 can form a predetermined temperature distribution on the glass plate 3 with high accuracy in the width direction of the glass plate 3.

(4-3)
In the cooling chamber 80, the glass plate 3 is gradually cooled as it is conveyed downward by the pulling rolls 82a to 82g. Further, as shown in FIG. 9, the heat energy distribution in the horizontal direction of the soaking plate 92a has a shape with a convex center. Therefore, regarding the five divided heat equalizing plates 94a1 to 94a5 constituting the heat equalizing plate 92a, the temperature of the central divided heat equalizing plate 94a3 is higher than the temperature of the divided heat equalizing plates 94a2 and 94a4 on both sides thereof, and The temperature of the hot plates 94a2 and 94a4 is higher than the temperature of the split soaking plates 94a1 and 94a5 at both ends. The same applies to the other soaking plates 92b to 92g.

  In addition, regarding the soaking plate 92a, boundaries B1 to B4 between the two divided soaking plates 94a1 to 94a5 adjacent in the horizontal direction are straight lines inclined with respect to the vertical direction. As shown in FIG. 6, the boundaries B <b> 1 to B <b> 4 are straight lines that are inclined toward the conveyance direction of the glass plate 3 toward the center line C.

  Therefore, the temperature of the soaking plate 92a tends to decrease as it goes downward from above on a line that crosses the boundaries B1 to B4 in the vertical direction. For example, the divided soaking plate 94a2 is disposed above the boundary B1, and the divided soaking plate 94a1 is disposed below the boundary B1. As described above, the temperature of the split soaking plate 94a2 is higher than the temperature of the split soaking plate 94a1. On the line that crosses the boundary B1 in the vertical direction, the divisional heat equalizing plate 94a2 moves to the divided heat equalizing plate 94a1 as it goes downward from above. Therefore, on this line, the temperature of the soaking plate 92a tends to decrease as it goes from the top to the bottom. The same applies to the other soaking plates 92b to 92g.

  Therefore, the glass plate manufacturing apparatus 1 is gradually cooled as the glass plate 3 is conveyed downward due to the shape of the boundaries B1 to B4 between the two divided heat equalizing plates 94a1 to 94a5 adjacent in the horizontal direction. As described above, the temperature distribution in the horizontal direction of each of the soaking plates 92a to 92g can be appropriately formed.

(4-4)
In each of the heaters 84a to 84g, the number of the heat sources 91a to 91g is equal to the number of the soaking plates 92a to 92g. The soaking plates 92a to 92g correspond to the heat sources 91a to 91g on a one-to-one basis. For example, the soaking plate 92a corresponds to the heat source 91a, and the temperature of the soaking plate 92a is adjusted mainly by controlling the output of the heat source 91a. Therefore, the temperature of each of the soaking plates 92a to 92g can be adjusted with high accuracy by controlling the output of the corresponding heat sources 91a to 91g. Therefore, the glass plate manufacturing apparatus 1 can form a predetermined temperature distribution on the glass plate 3 with high accuracy in the width direction of the glass plate 3.

(4-5)
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, the soaking plate 92a is composed of five divided soaking plates 94a1 to 94a5. The divided soaking plates 94a1 to 94a5 are adjacent to each other in the horizontal direction. However, the divided soaking plates 94a1 to 94a5 may be coupled to each other in the horizontal direction via a heat insulating member.

  FIG. 10 is a plan view of a heat equalizing plate 192a according to this modification. The soaking plate 192a corresponds to the soaking plate 92a of the present embodiment. The soaking plate 192a is composed of five divided soaking plates 194a1 to 194a5. FIG. 11 is a plan view of a connecting portion between the divided soaking plates 194a1 and 194a2 adjacent in the horizontal direction. FIG. 11 is an enlarged view of the soaking plate 192a shown in FIG. 10 viewed from the back side. FIG. 12 is a side view of the heat equalizing plate 192a viewed from the arrow XII in FIG. The shapes of the divided soaking plates 194a1 to 194a5 are substantially the same as the shapes of the divided soaking plates 94a1 to 94a5 of the embodiment, respectively. In the heat equalizing plate 192a, the shapes of the boundaries B11 to B14 between the two divided heat equalizing plates 194a1 to 194a5 adjacent in the horizontal direction are substantially the same as the shapes of the boundaries B1 to B4 of the embodiment, respectively.

  As shown in FIG. 11 and FIG. 12, the divided heat equalizing plates 194a1 and 194a2 have fixing portions 195a1 and 195a2, respectively. A boundary B11 inclined with respect to the vertical direction is formed between the divided soaking plates 194a1 and 194a2. The fixed portion 195a1 is a protrusion that rises in the direction away from the glass plate 3 at the end on the boundary B11 side of the divided soaking plate 194a1. The fixing portion 195a2 is a protrusion that rises in a direction away from the glass plate 3 at the end on the boundary B11 side of the divided soaking plate 194a2.

  A thin heat insulating member 196 is disposed between the divided soaking plate 194a1 and the divided soaking plate 194a2. The heat insulating member 196 is, for example, a heat-resistant ceramic fiber. As the heat insulating member 196, Isowool manufactured by Isolite Industry Co., Ltd. may be used. The heat insulating member 196 is sandwiched between the fixed portion 195a1 of the divided soaking plate 194a1 and the fixing portion 195a2 of the divided soaking plate 194a2. And the fixing | fixed part 195a1, the heat insulation member 196, and the fixing | fixed part 195a2 are mutually fixed with the rivet 197. The rivet 197 passes through the fixed portion 195a1, the heat insulating member 196, and the fixed portion 195a2. The other divided soaking plates 194a2 to 194a5 are similarly connected to each other by a heat insulating member 196 and a rivet 197.

  In this modification, the heat equalizing plate 192a is composed of five divided heat equalizing plates 194a1 to 194a5 connected to each other through a heat insulating member 196. The heat insulating member 196 suppresses the movement of heat between the two divided soaking plates 194a1 to 194a5 adjacent to each other. For example, in the soaking plate 192a, the temperature of the divided soaking plate 194a1 is hardly changed due to the influence of the temperature of the dividing soaking plate 194a2. As a result, a more complicated and more flexible temperature distribution in the horizontal direction can be formed on the soaking plate 192a. Therefore, a predetermined temperature distribution can be formed on the surface of the glass plate 3 with higher accuracy in the width direction of the glass plate 3.

(5-2) Modification B
In the present embodiment, the soaking plate 92a is composed of five divided soaking plates 94a1 to 94a5. In the heat equalizing plate 92a, the boundaries B1 to B4 between the two divided heat equalizing plates 94a1 to 94a5 that are adjacent to each other in the horizontal direction are, as shown in FIG. It is a straight line that inclines toward

  However, the boundaries B1 to B4 of the divided heat equalizing plates 94a1 to 94a5 may be, for example, arcs, or may be line segments composed of a plurality of straight lines and curves. FIG. 13 is a plan view of a heat equalizing plate 292a showing an example of this modification. The soaking plate 292a is composed of five divided soaking plates 294a1 to 294a5. In the heat equalizing plate 292a, the boundaries B21 to B24 between the two divided heat equalizing plates 294a1 to 294a5 adjacent in the horizontal direction are not line segments composed of a single straight line. As shown in FIG. 13, the boundaries B21 to B24 are composed of a plurality of straight lines and curves. The boundaries B <b> 21 to B <b> 24 are line segments that gradually move in the transport direction of the glass plate 3 toward the center line C as in the boundaries B <b> 1 to B <b> 4 of the present embodiment. The shapes of the boundaries B21 to B24 may be appropriately determined according to the temperature distribution of the soaking plate 292a in the width direction of the glass plate 3.

(5-3) Modification C
In the present embodiment, the heater 84a includes five divided heaters 85a1 to 85a5. The heat source 91a of the heater 84a includes five divided heat sources 93a1 to 93a5. The soaking plate 92a of the heater 84a is composed of five divided soaking plates 94a1 to 94a5. Each of the divided heaters 85a1 to 85a5 includes one divided heat source 93a1 to 93a5 and one corresponding divided heat equalizing plate 94a1 to 94a5. That is, the divided heat equalizing plates 94a1 to 94a5 correspond one-to-one with the divided heat sources 93a1 to 93a5.

  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,... Provided in the heater 84a increases, a more complicated and more flexible temperature distribution can be formed on the heat equalizing plate 92a of the heater 84a. . As a result, the temperature distribution in the width direction can be formed with higher accuracy on the surface of the glass plate 3 facing the soaking plate 92a.

(5-4) Modification D
In the present embodiment, the soaking plate 92a is composed of five divided soaking plates 94a1 to 94a5. In the heat equalizing plate 92a, the boundaries B1 to B4 between the two divided heat equalizing plates 94a1 to 94a5 that are adjacent to each other in the horizontal direction are, as shown in FIG. It is a straight line that inclines toward

  However, regarding the five divided heat sources 93a1 to 93a5 constituting the heat source 91a, the boundaries between the two divided heat sources 93a1 to 93a5 adjacent in the horizontal direction are the same as the boundaries B1 to B4 of the soaking plate 92a. It may be a straight line inclined with respect to the transport direction. For example, even if the shapes of the divided heat source 93a1 and the divided heat source 93a2 are set so that the boundary between the divided heat source 93a1 and the divided heat source 93a2 has the same shape as the boundary B1 of the heat equalizing plate 92a shown in FIG. Good.

  In the present modification, the boundary between the two divided heat sources 93a1 to 93a5 that are adjacent in the horizontal direction may be a segment composed of a plurality of straight lines and curves, as in Modification B. Moreover, in this modification, the boundary between the two division | segmentation soaking plates 94a1-94a5 adjacent to a horizontal direction is a straight line inclined with respect to the conveyance direction of the glass plate 3 similarly to boundary B1-B4. It may be a straight line parallel to the conveying direction of the glass plate 3.

(5-5) Modification E
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)
85a1-85a5 Split heater (split heating means)
94a1-94a5 Divided soaking plate (thermal radiation member)
196 Thermal insulation member

JP 2001-31435 A JP 2007-112665 A

Claims (8)

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 heating means is divided into a plurality of divided heating means along the width direction,
In each of the heating means, at least one of the divided heating means has a shape in which the position adjacent to the other divided heating means in the width direction changes in the transport direction.
Glass plate manufacturing method. The divided heating means has a heat radiation member having a facing surface facing the surface of the glass plate,
The heat radiation member radiates heat from the facing surface toward the surface of the glass plate.
The glass plate manufacturing method of Claim 1. In each of the heating means, the heat radiation member is connected to each other via a heat insulating member,
The glass plate manufacturing method according to claim 2. In each of the heating means, at least one of the heat radiation members has a shape in which the position adjacent to the other heat radiation members in the width direction changes in the transport direction.
The glass plate manufacturing method of Claim 3. In each of the heating means, the number of the divided heating means is equal to the number of the heat radiation members.
The glass plate manufacturing method of any one of Claim 2 to 4. The cooling step is performed when the maximum value of the temperature of the glass plate in the width direction is between the vicinity of the annealing point of the glass plate and the vicinity of the strain point.
The glass plate manufacturing method of any one of Claim 1 to 5. The strain point of the glass plate is 675 ° C. to 725 ° C.,
The glass plate manufacturing method of any one of Claim 1 to 6. 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, and is divided into a plurality of divided heating means along the width direction,
In each of the heating means, at least one of the divided heating means has a shape in which the position adjacent to the other divided heating means in the width direction changes in the transport direction.
Glass plate manufacturing equipment.

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