JP2017048102A - Manufacturing method of glass substrate, and manufacturing apparatus of glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method or the like of a glass substrate capable of suppressing deformation of a glass ribbon (glass substrate) caused by creep deformation of a compact.SOLUTION: A manufacturing method of a glass substrate includes a shaping step for supplying molten glass 2 to a supply groove formed on a top face of a compact 62, letting the molten glass 2 overflowing from both sides of the supply groove flow downward along both side faces of the compact 62, and merging the molten glass 2 flowing downward along both side faces at a bottom edge 62a of the compact 62 to shape a glass ribbon 3; and a controlling step for controlling tensile force in the width direction of the glass ribbon 3 caused by cooling both sides 3b in the width direction of the shaped glass ribbon 3 in accordance with shape change of the compact 62 accompanying use of the compact 62.SELECTED DRAWING: Figure 8

Description

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

  A glass substrate used for a flat panel display (FPD) such as a liquid crystal display and a plasma display is required to have high flatness on the surface. Usually, such a glass substrate is manufactured by the overflow down draw method. In the overflow downdraw method, as described in Patent Document 1, the molten glass that has flowed into the groove on the upper surface of the molded body and overflowed from the groove flows down on both side surfaces of the molded body, and lowers the lower end of the molded body. The glass ribbon is formed by joining. The formed glass ribbon is gradually cooled while being pulled downward. The cooled glass ribbon is cut into a predetermined dimension to obtain a glass substrate.

U.S. Pat. No. 3,338,696

  In the overflow down draw method, the molded body is placed in a high-temperature atmosphere in a molding furnace. Moreover, the weight of the dead weight and molten glass is applied to the molded body as a load. For this reason, the molded body gradually creep-deforms due to the thermal creep characteristics of the material of the molded body due to the long-term operation of the glass substrate manufacturing apparatus. In particular, the central portion in the longitudinal direction of the molded body is likely to sag downward due to creep deformation and bend easily. As a result, the amount of molten glass that overflows from the center of the molded body is greater than the amount of molten glass that overflows from both ends of the molded body, and the thickness of the central portion in the width direction of the glass ribbon to be molded increases. There was a problem that the thickness deviation of the glass substrate as the final product increased.

  Creep deformation of a molded body is a particular problem because the temperature of the molded body tends to be high in the manufacturing process of a glass substrate using glass having a high liquidus temperature and glass having a high strain point. In recent years, the size of the glass substrate has been increased, and the dimension in the longitudinal direction of the molded body has become longer. Therefore, the bending of the molded body due to creep deformation tends to become more prominent.

  Then, this invention aims at providing the manufacturing method of the glass substrate which can suppress the deformation | transformation including the plate | board thickness deviation etc. of the glass ribbon (glass substrate) by creep deformation of a molded object, and the manufacturing apparatus of a glass substrate. .

The present invention has the following aspects.
(1)
The molten glass is supplied to a supply groove formed on the upper surface of the molded body, the molten glass overflowing from both sides of the supply groove is caused to flow down along both side surfaces of the molded body, and the molten glass is flowed down on both side surfaces. A molding step of forming a glass ribbon by joining glass at the lower end of the molded body; and
By cooling both sides in the width direction of the glass ribbon after the forming step, the tension applied in the width direction of the glass ribbon is controlled according to the shape change of the formed body that occurs with the use of the formed body. A method of manufacturing a glass substrate, comprising: a control step.

(2)
The control step includes
When the shape change is within a preset reference range, the tension applied in the width direction of the glass ribbon is maintained at a reference tension when there is no shape change, and the shape change exceeds the reference range. In this case, the method of manufacturing a glass substrate according to (1), including controlling the tension applied in the width direction of the glass ribbon to a tension larger than the reference tension according to the degree of the shape change.

(3)
The said shape change is a change in which the said upper surface of the said molded object changes from a plane to a curved surface along the direction where the said supply groove | channel of the said molded object is extended. Method.

(4)
In the control step, in addition to the reference tension applied in the width direction of the glass ribbon when the shape does not change in the width direction of the glass ribbon, the tension corresponding to the shape change of the formed body is The method for producing a glass substrate according to (1), comprising applying to a glass ribbon.

(5)
An acquisition step of acquiring the amount of vertical displacement of the upper surface of the molded body as information on the shape change;
A determination step of determining whether or not the displacement amount acquired in the acquisition step is equal to or less than a reference amount,
When it is determined in the determination step that the displacement amount exceeds the reference amount, the control step is based on a relational expression between a predetermined displacement amount of the formed body and a tension applied in the width direction of the glass ribbon. And the tension | tensile_strength corresponding to the acquired said displacement amount is determined, The manufacturing method of the glass substrate as described in any one of (1)-(4).

(6)
The glass substrate manufacturing method according to (5), wherein, in the control step, the tension is increased as the displacement amount is increased.

(7)
In the acquisition step, the displacement amount is acquired by obtaining a time change in the shape of the molded body by computer simulation, and the method for manufacturing a glass substrate according to (5) or (6).

(8)
In the said control process, the said tension | tensile_strength is controlled so that the plate | board thickness deviation of the thickness direction of the said glass ribbon may become below a reference value, The manufacturing method of the glass substrate as described in any one of (1)-(7).

(9)
The molten glass is supplied to a supply groove formed on the upper surface of the molded body, the molten glass overflowing from both sides of the supply groove is caused to flow down along both side surfaces of the molded body, and the molten glass is flowed down on both side surfaces. A molding device for forming glass ribbon by joining glass at the lower end of the molded body;
By cooling both sides in the width direction of the glass ribbon after the forming step, the tension applied in the width direction of the glass ribbon is controlled according to the shape change of the formed body that occurs with the use of the formed body. A control device;
An apparatus for producing a glass substrate, comprising:

(10)
In the control device, in addition to the reference tension applied in the width direction of the glass ribbon when the shape does not change in the width direction of the glass ribbon, the tension according to the shape change of the formed body is The apparatus for manufacturing a glass substrate according to (9), wherein cooling of both side portions in the width direction of the glass ribbon is controlled so as to be applied to the glass ribbon.

  The glass substrate manufacturing method and the glass substrate manufacturing apparatus described above can suppress deformation including a plate thickness deviation of the glass ribbon (glass substrate) due to creep deformation of the molded body.

It is a flowchart of an example of the manufacturing method of the glass substrate which concerns on this embodiment. It is a schematic diagram of an example of the manufacturing apparatus of the glass substrate used with the manufacturing method of the glass substrate of this embodiment. It is a front view of an example of the shaping | molding apparatus used with the manufacturing apparatus of the glass substrate shown in FIG. It is a side view of an example of the shaping | molding apparatus used with the manufacturing apparatus of the glass substrate shown in FIG. It is a front view of the vicinity of the upper shaping | molding space of the shaping | molding apparatus used with the manufacturing apparatus of the glass substrate shown in FIG. It is a block diagram of an example of a control device used in this embodiment. It is a figure explaining an example of the shape data of the forming object acquired by the acquisition part used by this embodiment. It is a figure which shows an example of the glass ribbon shape | molded with the molded object used by this embodiment. It is a figure which shows an example of the cross section of the glass ribbon shape | molded with the molded object which carried out creep deformation. It is a figure which shows an example of the relationship between the displacement amount of a molded object, and the tension | tensile_strength T applied to a glass ribbon. (A) is the figure which expanded the cross section along the AA line of FIG. 8, (b) is the figure which expanded the cross section along the BB line of FIG.

(1) Configuration of Glass Substrate Manufacturing Apparatus An embodiment of a glass substrate manufacturing method and 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 substrate manufacturing method according to the present embodiment.

  As FIG. 1 shows, the manufacturing method of the glass substrate which concerns on this embodiment mainly has melting process S1, clarification process S2, stirring process S3, shaping | molding process S4, cooling process S5, and cutting process 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 the environmental load, SnO ₂ is used as a fining 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 that is the cause of the striae of the glass substrate is reduced.

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

  In the cooling step S5, the glass ribbon formed in the forming step S4 is cooled while being conveyed downward. In the cooling step S5, the glass ribbon is gradually cooled while adjusting the temperature of the glass ribbon so that the glass ribbon is not distorted and warped.

  In cutting process S6, the glass ribbon cooled by cooling process S5 is cut | disconnected by a predetermined dimension, and a glass substrate is obtained. Thereafter, the end surface of the glass substrate is ground and polished, and the glass substrate is cleaned. Thereafter, the glass substrate is inspected for defects such as scratches, and the glass substrate that has passed the inspection is packed and shipped as a product.

  FIG. 2 is a schematic diagram illustrating an example of the glass substrate manufacturing apparatus 1 according to the present embodiment. The glass substrate manufacturing apparatus 1 includes a melting tank 10, a clarification tube 20, a stirring device 30, a molding 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 S4, the glass ribbon 3 is continuously formed from the molten glass 2 by the forming apparatus 40. In the cooling step S5, the glass ribbon 3 is cooled while being conveyed downward. In the cutting step S6, the cooled glass ribbon 3 is cut into a predetermined size to obtain a glass substrate. The width of the glass substrate is, for example, 500 mm to 3500 mm, and the length is, for example, 500 mm to 3500 mm. The thickness of the glass substrate is, for example, 0.2 mm to 0.8 mm.

The glass substrate manufactured by the glass substrate manufacturing apparatus 1 is particularly suitable as a glass substrate for a flat panel display (FPD) such as a liquid crystal display, a plasma display, and an organic EL display. As the glass substrate for FPD, non-alkali glass, glass containing a trace amount of alkali, glass for low temperature poly silicon (LTPS), or glass for oxide semiconductor is used. As a glass substrate for a high-definition display, a glass having a high viscosity and a high strain point at a high temperature is used. For example, glass used as a raw material for a glass substrate for a high-definition display has a viscosity of 10 ^2.5 poise at 1500 ° C. Since glass having a high temperature viscosity needs to have a higher temperature during molding, deformation due to thermal creep characteristics described later becomes more prominent.

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 a glass substrate having a desired composition can be obtained. As an example of the composition of the glass substrate, non-alkali glass suitable as a glass substrate for FPD is SiO ₂ : 50 mass% to 70 mass%, Al ₂ O ₃ : 10 mass% to 25 mass%, B ₂ O ₃ : 1% by mass to 18% 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.

In addition, a glass containing a trace amount of alkali metal containing a trace amount of alkali metal may be used as a glass substrate 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.

The glass substrate manufactured by the glass substrate 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 substrate manufactured by the glass substrate 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 forming apparatus 40, the glass ribbon 3 is formed from the molten glass 2 by the overflow downdraw method. Next, the detailed 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 as viewed from a direction perpendicular to the surface of the glass ribbon 3 formed by the forming apparatus 40. FIG. 4 is a side view of the molding apparatus 40. FIG. 4 shows the forming apparatus 40 as viewed from a direction parallel to the surface of the glass ribbon 3 formed by the forming apparatus 40.

  The forming apparatus 40 has a space surrounded by a furnace wall made of a refractory material such as a refractory brick. This space is a space in which the glass ribbon 3 is formed from the molten glass 2 and the glass ribbon 3 is cooled. This space includes three spaces, an upper molding space 60, a lower molding space 70, and a slow cooling space 80. FIG. 5 is a front view of the vicinity of the upper molding space 60 of the molding apparatus 40. The glass ribbon 3 has a side portion 3b (end portion, ear portion) located at an end portion in the width direction and a center region 3a in the width direction sandwiched between the side portions 3b. The central region 3a is a region that is a product region having a substantially constant thickness, and the side portion 3b is a region that is thicker than the central region 3a and has a bulbous shape.

  The molding step S4 is performed in the upper molding space 60. The cooling step S5 is performed in the lower molding space 70 and the slow cooling space 80. The upper molding space 60 is a space in which the molten glass 2 supplied from the stirring device 30 to the molding device 40 via the transfer pipe 50 c is molded into the glass ribbon 3. The lower molding space 70 is a space below the upper molding space 60, and is a space where the glass ribbon 3 is rapidly cooled to the vicinity of the annealing point of the glass. The slow cooling space 80 is a space below the lower molding space 70 and is a space where the glass ribbon 3 is gradually cooled.

  The molding apparatus 40 mainly includes a molded body 62, a plurality of heating elements, an upper partition member 64, a cooling roll 72, a temperature adjustment unit 74, a lower partition member 76, pulling rolls 82a to 82g, and a heater 84a. -84g, the heat insulation member 86, the cutting device 98, and the control apparatus 91 (refer FIG. 6). Next, each component of the shaping | molding apparatus 40 is demonstrated.

(2-1) Molded Body The molded body 62 is installed in the upper molding space 60. The formed body 62 is used for forming the glass ribbon 3 by overflowing the molten glass 2. 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 supply groove 62b is formed on the upper surface 62c of the molded body 62 along the longitudinal direction of the molded body 62 (the vertical direction in FIG. 4 and the horizontal direction in FIG. 5). A transfer pipe 50 c communicating with the supply groove 62 b is attached to the end of the molded body 62 in the longitudinal direction. The groove depth of the supply groove 62b is formed so as to gradually become shallower from one end communicating with the transfer pipe 50c toward the other end. Hereinafter, as shown in FIG. 3, of the pair of end portions in the longitudinal direction of the molded body 62, the end portion on the side communicating with the transfer pipe 50 c is referred to as a first end portion 62 d 1, and the opposite end thereof This part is called the second end part 62d2. The second end 62d2 of the molded body 62 is provided with a platinum guide (not shown) for blocking the flow of the molten glass 2 in the supply groove 62b.

  The molten glass 2 sent to the shaping | molding apparatus 40 from the stirring apparatus 30 is poured into the supply groove | channel 62b of the molded object 62 via the transfer pipe 50c. The molten glass 2 flows from the first end portion 62d1 toward the second end portion 62d2 in the supply groove 62b. The molten glass 2 overflowed from the supply 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 ribbon 3 is continuously shape | molded in the vicinity of the lower end 62a of the molded object 62. FIG. The molded glass ribbon 3 flows down through the upper molding space 60 and then is conveyed downward while being cooled in the lower molding space 70 and the slow cooling space 80. The temperature of the glass ribbon 3 immediately after being molded in the upper molding space 60 is 1100 ° C. or higher, and the viscosity is 25000 poise to 350,000 poise. For example, when manufacturing a glass substrate for a high-definition display, the strain point of the glass ribbon 3 formed by the molded body 62 is 655 ° C. to 750 ° C., preferably 680 ° C. to 730 ° C. The viscosity of the molten glass 2 that merges in the vicinity of the lower end 62a is 25000 poise to 100000 poise, preferably 32000 poise to 80000 poise.

  The control device (control unit) 91 controls the viscosity of both side portions 3b of the glass ribbon 3 by controlling the cooling amount of the cooling roll 72 described later. The glass ribbon 3 includes a central region 3a having a substantially constant thickness and side portions 3b having a thickness greater than that of the central region located at both ends of the central region 3a. When the cooling roll 72 cools the both side portions 3b of the glass ribbon 3, a tension is generated in the glass ribbon 3 in the direction from the central region 3a to the both side portions 3b. Therefore, the controller 91 controls the glass ribbon 3 by controlling the tension. The plate thickness of the ribbon 3 can be controlled.

(2-2) Upper Partition Member The upper partition member 64 is a pair of plate-like heat insulating members 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 ribbon 3 in the thickness direction. The upper partition member 64 partitions the upper molding space 60 and the lower molding space 70 and suppresses the movement of heat from the upper molding space 60 to the lower molding space 70.

(2-3) Cooling Roll The cooling roll 72 is a cantilever roll installed in the lower molding space 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 ribbon 3. As shown in FIG. 4, the cooling rolls 72 are disposed on both sides of the glass ribbon 3 in the thickness direction. The glass ribbon 3 is sandwiched between cooling rolls 72 on both sides in the width direction. The cooling roll 72 cools the glass ribbon 3 sent from the upper molding space 60.

  In the lower molding space 70, both side portions in the width direction of the glass ribbon 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 ribbon 3, the contact area of the cooling roll 72 and the glass ribbon 3 becomes large, and the cooling of the glass ribbon 3 by the cooling roll 72 is performed efficiently. . The cooling roll 72 gives the glass ribbon 3 a force that opposes the force by which pulling rolls 82a to 82g described later pull the glass ribbon 3 downward. The thickness of the glass ribbon 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 or a water cooling tube inside. The cooling roll 72 is cooled by an air cooling tube or a water cooling tube. The cooling roll 72 is brought into contact with the glass ribbon 3 by sandwiching both side portions in the width direction of the glass ribbon 3. Thereby, since heat is transmitted from the glass ribbon 3 to the cooling roll 72, both side portions in the width direction of the glass ribbon 3 are cooled. The viscosity of both side portions in the width direction of the glass ribbon 3 cooled in contact with the cooling roll 72 is, for example, 10 ^9.0 poise or more.

  The contact load between the cooling roll 72 and the glass ribbon 3 can be controlled by the control device 91. The contact load is controlled, for example, by adjusting the position of the cooling roll 72 using the air pressure of the air cylinder and the physical load of the spring. The larger the contact load, the stronger the force that the cooling roll 72 presses the glass ribbon 3. Even after the glass ribbon 3 is clamped by the cooling roll 72, the control device 91 controls the air cylinder air pressure and the load applied to the spring, thereby adjusting the vertical and horizontal positions of the cooling roll 72. Therefore, the glass ribbon 3 can be held with an appropriate force, and damage to the glass ribbon 3 can be suppressed.

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

  In the lower molding space 70, the glass ribbon 3 is cooled until the temperature at the center in the width direction of the glass ribbon 3 decreases to the vicinity of the annealing point. The temperature adjustment unit 74 adjusts the temperature of the glass ribbon 3 cooled in the lower forming space 70. The temperature adjustment unit 74 is a unit that heats or cools the glass ribbon 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 74 a adjusts the temperature of the central region 3 a in the width direction of the glass ribbon 3. The side cooling unit 74 b adjusts the temperature of both sides in the width direction of the glass ribbon 3. Here, the center region 3 a in the width direction of the glass ribbon 3 means a region sandwiched between the side portions 3 b on both sides in the width direction of the glass ribbon 3. The side portions 3b on both sides refer to regions in the range in the width direction from the ends on both sides of the glass ribbon 3 to the position advanced by, for example, 200 mm toward the inside in the width direction of the glass ribbon 3. The center region 3a is within a range of, for example, 85% or less of the width in the width direction of the glass ribbon 3 from the center in the width direction of the glass ribbon 3. The range of the central region 3a can vary depending on the length of the glass ribbon 3 in the width direction.

  In the lower molding space 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 ribbon 3 flows down. Yes. The center part cooling unit 74a is arranged so as to face the surface of the center part of the glass ribbon 3 in the width direction. The side cooling unit 74b is disposed so as to face the surfaces of both side portions of the glass ribbon 3 in the width direction.

  The temperature adjustment unit 74 is controlled by the control device 91. Each center part cooling unit 74a and each side part cooling unit 74b can be independently controlled by the control device 91.

(2-5) Lower Partition Member The lower partition member 76 is a pair of plate-like heat insulating members installed below the temperature adjustment unit 74. As shown in FIG. 4, the lower partition member 76 is installed on both sides of the glass ribbon 3 in the thickness direction. The lower partition member 76 partitions the lower molding space 70 and the slow cooling space 80 in the vertical direction, and suppresses the movement of heat from the lower molding space 70 to the slow cooling space 80.

(2-6) Pull-down rolls The pull-down rolls 82 a to 82 g are cantilever rolls installed in the slow cooling space 80. In the slow cooling space 80, a pulling roll 82a, a pulling roll 82b,..., A pulling roll 82f, and a pulling roll 82g are arranged at intervals from above to below. The pulling roll 82a is disposed at the uppermost position, and the pulling roll 82g is disposed at the lowermost position.

  As shown in FIG. 3, the pulling rolls 82 a to 82 g are respectively disposed on both sides of the glass ribbon 3 in the width direction. As shown in FIG. 4, the pulling rolls 82 a to 82 g are respectively disposed on both sides of the glass ribbon 3 in the thickness direction. That is, the two sides of the glass ribbon 3 in the width direction are directed from the top to the bottom, two pairs of pulling rolls 82a, two pairs of pulling rolls 82b, ..., two pairs of pulling rolls 82f and two pairs of pulling rolls. It is sandwiched by 82g.

  The pulling rolls 82a to 82g pull the glass ribbon 3 downward in the vertical direction by rotating while sandwiching both end portions in the width direction of the glass ribbon 3 that has passed through the lower forming space 70. That is, the pulling rolls 82a to 82g are rolls for conveying the glass ribbon 3 downward.

  The angular velocities of the pulling rolls 82a to 82g can be controlled independently by the control device 91. The higher the angular speed of the pulling rolls 82a to 82g, the higher the speed at which the glass ribbon 3 is conveyed downward.

(2-7) Heater The heaters 84 a to 84 g are installed in the slow cooling space 80. As shown in FIG. 4, in the slow cooling space 80, the heater 84a, the heater 84b,..., The heater 84f and the heater 84g are arranged at intervals from the upper side to the lower side. The heaters 84a to 84g are respectively disposed on both sides of the glass ribbon 3 in the thickness direction. The pulling rolls 82a to 82g are disposed between the heaters 84a to 84g and the glass ribbon 3, respectively.

  The heaters 84 a to 84 g radiate heat toward the surface of the glass ribbon 3 to heat the glass ribbon 3. By using the heaters 84a to 84g, the temperature of the glass ribbon 3 conveyed downward in the slow cooling space 80 can be adjusted. Accordingly, the heaters 84 a to 84 g can form a predetermined temperature distribution on the glass ribbon 3 in the conveyance direction of the glass ribbon 3.

  The outputs of the heaters 84a to 84g can be controlled independently by the control device 91. The heaters 84a to 84g are divided into a plurality of heater subunits (not shown) along the width direction of the glass ribbon 3, and the output of each heater subunit can be controlled independently by the controller 91. Also good. In this case, the heaters 84 a to 84 g can form a predetermined temperature distribution in the width direction of the glass ribbon 3 by changing the heat generation amount according to the position in the width direction of the glass ribbon 3.

  In addition, the thermocouple (not shown) which measures the temperature of the atmosphere of the slow cooling space 80 is installed in the vicinity of each heater 84a-84g. The thermocouple measures, for example, the ambient temperature near the center of the glass ribbon 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 slow cooling space 80 measured by a thermocouple.

(2-8) Heat insulation member The heat insulation member 86 is installed in the slow cooling space 80. The heat insulating member 86 is installed at a height position between two pulling rolls 82 a to 82 g adjacent along the conveying direction of the glass ribbon 3. As shown in FIG. 4, the heat insulating member 86 is a pair of heat insulating plates arranged horizontally on both sides of the glass ribbon 3 in the thickness direction. The heat insulating member 86 partitions the slow cooling space 80 in the vertical direction and suppresses the movement of heat in the vertical direction in the slow cooling space 80.

  The heat insulating member 86 is installed so as not to contact the glass ribbon 3 conveyed downward. Moreover, the heat insulation member 86 is installed so that the distance to the surface of the glass ribbon 3 can be adjusted. Thereby, the heat insulating member 86 suppresses the movement of heat between the space above the heat insulating member 86 and the space below the heat insulating member 86.

(2-9) Cutting Device The cutting device 98 is installed in a space below the slow cooling space 80. The cutting device 98 cuts the glass ribbon 3 that has passed through the slow cooling space 80 along the width direction of the glass ribbon 3 for each predetermined dimension. The glass ribbon 3 that has passed through the slow cooling space 80 is a flat glass ribbon 3 that is cooled to near room temperature.

  The cutting device 98 cuts the glass ribbon 3 at predetermined time intervals. Thereby, when the conveyance speed of the glass ribbon 3 is constant, the glass substrate which has a dimension close | similar to a final product is mass-produced.

(2-10) Control Device The control device 91 is a computer mainly composed of a CPU, RAM, ROM, hard disk, and the like. FIG. 6 is a block diagram of the control device 91. As shown in FIG. 6, the control device 91 is connected to a cooling roll drive motor 172, a temperature adjustment unit 74, a pulling roll drive motor 182, heaters 84 a to 84 g, and a cutting device drive motor 198. The cooling roll drive motor 172 is a motor for controlling the position and rotational speed of the cooling roll 72. The pulling roll drive motor 182 is a motor for independently controlling the positions and rotational speeds of the pulling rolls 82a to 82g. The cutting device drive motor 198 is a motor for controlling a time interval or the like at which the cutting device 98 cuts the glass ribbon 3. The control device 91 stores a program for acquiring the state of each component and controlling each component.

  The control device 91 can acquire and adjust the contact load between the pair of cooling rolls 72 and the glass ribbon 3 that sandwich the side portion in the width direction of the glass ribbon 3 by controlling the cooling roll drive motor 172. The control device 91 individually controls the cooling amount of each cooling roll. The control device 91 can control the pulling roll drive motor 182 to acquire the torques of the rotating pulling rolls 82a to 82g and adjust the angular velocities of the pulling rolls 82a to 82g. For example, the control device 91 acquires the contact load and torque from torque sensors (not shown) attached to the cooling roll 72 and the pulling rolls 82a to 82g. Instead of the torque sensor, the control device 91 calculates the actual output torque based on the detection value from the current sensor that detects the current supplied to the cooling roll drive motor 172 and the pulling roll drive motor 182. The actual output torque can also be acquired. The control device 91 individually controls the cooling amount of each roll while controlling the rotation amounts of the cooling roll 72 and the pulling rolls 82a to 82g based on the acquired torque. The control device 91 can adjust the output of the temperature adjustment unit 74 and the outputs of the heaters 84a to 84g. The controller 91 can control the cutting device drive motor 198 to adjust the time interval at which the cutting device 98 cuts the glass ribbon 3.

(3) Operation of Molding Device In the upper molding space 60, the molten glass 2 sent from the stirring device 30 to the molding device 40 via the transfer pipe 50c enters the supply groove 62b formed on the upper surface 62c of the molded body 62. Supplied. The molten glass 2 overflowed from the supply groove 62 b of the molded body 62 flows down along both side surfaces of the molded body 62 and joins in the vicinity of the lower end 62 a of the molded body 62. In the vicinity of the lower end 62a of the formed body 62, the glass ribbon 3 is continuously formed from the molten glass 2 that has joined. The molded glass ribbon 3 is sent to the lower molding space 70.

  In the lower molding space 70, both side portions of the glass ribbon 3 in the width direction are brought into contact with the cooling roll 72 and rapidly cooled. Moreover, the temperature of the glass ribbon 3 is adjusted by the temperature adjustment unit 74 until the temperature of the center part of the width direction of the glass ribbon 3 falls to a slow cooling point. The glass ribbon 3 cooled while being conveyed downward by the cooling roll 72 is sent to the slow cooling space 80.

  In the slow cooling space 80, the glass ribbon 3 is gradually cooled while being pulled down by the pulling rolls 82a to 82g. The temperature of the glass ribbon 3 is controlled by the heaters 84 a to 84 g so that a predetermined temperature distribution is formed along the width direction of the glass ribbon 3. In the slow cooling space 80, the temperature of the glass ribbon 3 gradually decreases from the vicinity of the slow cooling point to a temperature lower than a temperature 200 ° C. lower than the strain point.

  The glass ribbon 3 that has passed through the slow cooling space 80 is further cooled to near room temperature, and is cut into a predetermined size by a cutting device 98 to obtain a glass substrate. Thereafter, polishing and cleaning of the end face of the glass substrate are performed. Thereafter, the glass substrate that has passed the predetermined inspection is packed and shipped as a product.

(4) Operation of Control Device The control device 91 includes a transport unit 91a, an acquisition unit 91b, a determination unit 91c, and a control unit 91d, which are formed by storing and executing at least four programs. It is a module.
The control device 91 cools both side portions in the width direction of the glass ribbon 3 obtained in the forming step S4, so that tension applied in the width direction of the glass ribbon 3 is used with the use of the formed body 62 as described later. It controls according to the shape change of the molded object 62 which arises.

  The transport unit 91 a transports the glass ribbon 3 formed by the molded body 62 downward at a predetermined transport speed in the slow cooling space 80 using the pulling rolls 82 a to 82 g installed below the molded body 62. Adjust the operation. The conveyance unit 91a controls the pulling roll drive motor 182 to adjust the rotation speed of the pulling rolls 82a to 82g, thereby adjusting the conveyance speed of the glass ribbon 3.

  The acquisition unit 91b acquires shape data related to the current shape of the molded body 62 by obtaining a time change (shape change) of the shape of the molded body 62 by computer simulation. Specifically, the acquisition unit 91b acquires the current shape data of the molded body 62 based on the creep characteristic parameter. The creep characteristic parameter is a parameter for reproducing the relationship between the stress applied to the molded body 62, the temperature of the molded body 62, and the strain rate of the molded body 62 due to creep deformation. The creep characteristic parameter is a parameter determined by, for example, the material of the molded body 62, the usage time, the size, the weight, the temperature, the stress applied to the molded body 62, and the temperature of the molten glass 2. The creep characteristic parameter increases as the temperature of the molded body 62 increases and as the stress applied to the molded body 62 increases, and the amount of deformation of the shape of the molded body 62 increases. Here, the stress applied to the molded body 62 is a force that compresses the molded body 62 along the longitudinal direction of the molded body 62. Further, it is assumed that the strain rate of the molded body 62 is constant regardless of time. First, the acquisition unit 91b acquires information on the temperature-dependent change of the molded body 62 of the strain rate of the molded body 62 under the condition that the stress applied to the molded body 62 is constant. Next, the acquisition unit 91b acquires information on the stress-dependent change applied to the molded body 62 of the strain rate of the molded body 62 under the condition that the temperature of the molded body 62 is constant. Next, the acquisition unit 91b determines a creep characteristic parameter that can reproduce the measured values of the temperature-dependent change and the stress-dependent change of the strain rate of the molded body 62. And the acquisition part 91b calculates the strain rate of the molded object 62 on the conditions of predetermined | prescribed temperature and stress using the determined creep characteristic parameter by computer simulation. Furthermore, the acquisition unit 91b acquires the current shape data of the molded body 62 by obtaining a temporal change in the shape of the molded body 62 using the calculated strain rate. FIG. 7 is an example of the shape data of the molded body 62 acquired by the acquisition unit 91b. FIG. 7 shows the molded body 62 viewed from a direction perpendicular to the surface of the glass ribbon 3 formed by the molded body 62. In FIG. 7, the creep deformation of the molded body 62 is shown more emphasized than actual. In FIG. 7, the shape of the unused molded body 62, that is, the shape of the molded body 62 before creep deformation is indicated by a dotted line, and the molded body 62 after creep deformation with use of the molded body 62 is shown. The current shape is indicated by a solid line.

  The acquisition unit 91b acquires at least the upper surface displacement amount, which is the vertical displacement amount L of the upper surface 62c of the molded body 62, from the shape data based on the creep deformation of the molded body 62 as information on the shape change of the molded body 62. In FIG. 7, the upper surface displacement amount is a vertical dimension difference between the upper surface 62c before creep deformation and the upper surface 62c after creep deformation. In FIG. 7, the maximum upper surface displacement amount that is the maximum value of the upper surface displacement amount in the longitudinal direction of the molded body 62 is shown as the upper surface displacement amount. Moreover, the acquisition part 91b acquires the thickness data of the glass substrate measured by the glass substrate shape measuring apparatus (not shown). The thickness data is, for example, a profile in the width direction of the thickness of the glass substrate manufactured by the glass substrate manufacturing apparatus 1.

  The determination unit 91c determines whether or not the displacement amount L acquired by the acquisition unit 91b is equal to or less than a reference amount. Here, the reference amount means that a certain tension (initial tension) is applied to the glass ribbon 3 to form the glass ribbon 3 (glass substrate) to a thickness to be formed (for example, 0.2 mm to 0.8 mm). In this case, the thickness tolerance is an amount that can satisfy ± 0.05 mm, for example. When the tension applied to the glass ribbon 3 is not changed from the initial value, when the displacement L exceeds the reference amount, the thickness tolerance of the glass ribbon 3 exceeds ± 0.05 mm, for example. For this reason, by increasing the tension applied to the glass ribbon 3 from the initial tension, the thickness tolerance of the glass ribbon 3 is controlled to be within ± 0.05 mm, for example. The reference amount can be arbitrarily changed according to the initial tension, the thickness of the glass ribbon 3 to be molded, the thickness tolerance, etc., and is, for example, 3 mm to 30 mm.

When the molded body 62 is not displaced, that is, when the displacement amount L is 0, the control unit 91d sets the tension applied in the width direction of the molded glass ribbon 3 as the reference tension (initial tension), and cools the molded body 62d. By controlling the cooling amount of the roll 72, both side portions 3b in the width direction of the glass ribbon 3 are cooled, so that the tension applied to the glass ribbon 3 becomes the reference tension. In a state where the formed body 62 is not displaced, by applying a reference tension in the width direction of the glass ribbon 3, the glass ribbon 3 has a plate thickness to be formed, and a plate thickness tolerance satisfies ± 0.05 mm. Further, when the upper displacement amount L is not 0 but is equal to or less than the reference amount, the thickness of the glass ribbon 3 is obtained by applying this reference tension to the glass ribbon 3, that is, without changing the cooling amount of the cooling roll 72. The tolerance can be, for example, ± 0.05 mm or less.
When the molded body 62 undergoes creep deformation and the displacement amount L exceeds the reference amount, if the cooling amount of the cooling roll 72 is maintained without being controlled, that is, if the tension applied to the glass ribbon 3 remains the reference tension, The glass ribbon 3 having a thickness to be formed is not formed, and the thickness tolerance does not satisfy ± 0.05 mm. For this reason, the controller 91d applies a tension corresponding to the displacement of the molded body 62 to the glass ribbon 3 in addition to the reference tension. Here, the displacement of the molded body 62 is, for example, an upper surface displacement in the longitudinal direction of the molded body 62. Based on the shape data of the molded body 62 acquired by the acquisition unit 91b, the control unit 91d adjusts the thickness of the glass ribbon 3 to the thickness to be molded, and the thickness deviation of the glass ribbon 3 in the width direction. The tension applied to the glass ribbon 3 is controlled by controlling the cooling amount of the cooling roll 72 so as to be small. The shape data of the molded body 62 is, for example, a shape profile that is a profile of the upper surface displacement amount in the longitudinal direction of the molded body 62. The control unit 91d controls the cooling amount of the cooling roll 72 so that the tension in the width direction of the glass ribbon 3 increases as the displacement amount L obtained from the shape profile increases. As the displacement amount L obtained from the shape profile, for example, the maximum upper surface displacement amount is used. Thus, the shape change of the molded body 62 is a change in which the upper surface of the molded body 62 changes from a flat surface to a curved surface along the direction in which the supply groove 62b of the molded body 62 extends. The quantity L is used in this embodiment.

  FIG. 8 is a view showing an example of the glass ribbon 3 formed by the formed body 62. When the glass ribbon 3 molded at the lower end 62a of the molded body 62 moves away from the lower end 62a, the central region 3a starts to shrink toward the center in the width direction due to its surface tension. Therefore, the cooling roll 72 cools both side portions 3b of the glass ribbon 3 to increase the viscosity of both side portions 3b, and the glass ribbon 3 is moved in the width direction so that tension is applied from the central region 3a toward the both side portions 3b. And the thickness of the central region 3a of the glass ribbon 3 is made uniform. However, when the molded body 62 undergoes creep deformation, the amount of molten glass near the central region 3a of the glass ribbon 3 increases, and the thickness of the central region 3a changes. FIG. 9 is a view showing an example of the glass ribbon 3 whose thickness near the central region 3a is increased by creep deformation of the molded body 62. As shown in FIG. When the molded body 62 undergoes creep deformation, the amount of the molten glass 2 overflowing from between the first end portion 62d1 and the second end portion 62d2 increases, so that the thickness in the vicinity of the central region 3a of the glass ribbon 3 increases. In FIG. 9, the thickness in the vicinity of the central region 3a is D1 thicker than the thickness to be formed, and the thickness of the central region 3a is not uniform. Therefore, the control unit 91d changes the cooling amount of the cooling roll 72 according to the shape data of the formed body 62 so that tension is applied from the central region 3a of the glass ribbon 3 toward both side portions 3b. Is suppressed in the width direction, and the thickness of the central region 3a of the glass ribbon 3 is made uniform.

FIG. 10 is a diagram showing the relationship between the displacement amount L of the molded body 62 and the tension T applied to the glass ribbon 3. When the determination unit 91c determines that the displacement amount L of the molded body 62 does not exceed L1, the control unit 91d can ignore the change in the thickness of the central region 3a of the glass ribbon 3 due to the creep deformation of the molded body 62. That is, assuming that the plate thickness tolerance satisfies, for example, ± 0.05 mm, the tension T applied to the glass ribbon 3 is not changed from the initial value T1 (range of displacement L: 0 or more and L1 or less). If the displacement amount L of the molded body 62 is equal to or less than L1, the control unit 91d maintains the tension T at the initial value T1 without changing the cooling amount of the cooling roll 72, thereby forming the glass ribbon 3 to be molded. The thickness tolerance satisfies ± 0.05mm. When the determination unit 91c determines that the displacement amount L of the molded body 62 exceeds L1, the control unit 91d applies a tension T corresponding to the displacement amount L to the glass ribbon 3 as illustrated in FIG. To control. When the displacement amount L exceeds L1, as shown in FIG. 9, the thickness of the central region 3a of the glass ribbon 3 increases and the thickness becomes non-uniform. Therefore, the control unit 91d has a tension T = T1 + A × displacement amount L (the displacement amount L of the displacement amount L) larger than the initial value T1 from the central region 3a of the glass ribbon 3 toward the both side portions 3b so as to correspond to the displacement amount L. The range is controlled so that the range: L1 or more and less than Lm, A: coefficient) is applied to the glass ribbon 3. Specifically, the control unit increases the cooling amount of the cooling roll 72 to increase the viscosity of the both side portions 3b. When the viscosity of both side portions 3b is increased, the tension T from the central region 3a toward both side portions 3b is increased, and the molten glass in the central region 3a of the glass ribbon 3 is pulled to both side portions 3b, so that the thickness of the central region 3a is increased. The thickness becomes uniform as it approaches the thickness to be molded. The control unit 91d controls the tension T to be increased by increasing the viscosity of the both side portions 3b from, for example, 10 ^9.0 poise to 10 ^14.5 poise. Thus, the control process performed by the control unit 91d is within the reference range in which the shape change of the molded body 62, specifically, the displacement amount L of the molded body 62 is set in advance (the displacement amount L is L1 or less). In this case, the tension applied in the width direction of the glass ribbon 3 is maintained at the reference tension (initial value T1) when there is no shape change, and the shape change of the molded body 62, specifically, the amount of displacement of the molded body 62. When L exceeds the reference range (displacement amount L exceeds L1), the tension applied in the width direction of the glass ribbon 3 is set to a tension larger than the reference tension (initial value T1) according to the degree of shape change of the molded body 62. Controlling.
When the range of the displacement L is not less than L1 and less than Lm, the thickness of the central region 3a approaches the thickness to be formed by controlling the tension T from T1 to Tm, but the thickness becomes uniform. When the displacement amount L exceeds Lm, it is difficult to make the thickness uniform while keeping the thickness of the central region 3a close to the thickness to be formed only by controlling the tension T. Thus, it is determined that the periodic replacement time of the molded body 62 has been reached.

  Further, due to creep deformation of the molded body 62, the surface unevenness difference (plate thickness deviation) of the glass ribbon 3 also changes. Since the volume shrinkage of the glass ribbon 3 immediately after passing through the lower end 62a of the formed body 62 increases from the side 3b of the glass ribbon 3 toward the central region 3a, tensile stress acts in the central region 3a of the glass ribbon 3. As the thickness in the vicinity of the central region 3a increases and the tension from the side portions 3b toward the central region 3a increases, the surface unevenness difference of the glass ribbon 3 increases. 11A is an enlarged view of the cross section taken along the line AA in FIG. 8, and FIG. 11B is an enlarged view of the cross section taken along the line BB in FIG. Before the tension T is applied to the glass ribbon 3 by the cooling roll 72, the glass ribbon 3 contracts toward the central region 3 a, so that the surface unevenness difference of the glass ribbon 3 becomes D 2, and the tension is applied to the glass ribbon 3 by the cooling roll 72. After applying T, the surface unevenness difference of the glass ribbon 3 becomes D3 smaller than D2. When the molded body 62 undergoes creep deformation, the surface unevenness differences D2 and D3 of the glass ribbon 3 also increase. For this reason, since the glass ribbon 3 is pulled by the both side parts 3b by applying the tension T which goes to the both side parts 3b from the center area | region 3a so that it may respond | correspond to the displacement amount L, the surface uneven | corrugated difference D3 of the glass ribbon 3 is small. Become. By applying a tension T so as to correspond to the displacement L in order to bring the thickness of the central region 3a close to the thickness to be formed, the surface unevenness difference D3 of the glass ribbon 3 is reduced, and the central region 3a of the glass ribbon 3 is reduced. The thickness becomes uniform.

  Moreover, the control part 91d can also suppress striae that may occur in the transport direction of the glass ribbon 3 by applying a tension T to the glass ribbon 3. The striae is a kind of distortion in which the thickness (height) of the glass ribbon 3 fluctuates within a predetermined width, and is continuously generated in a streak shape in the conveyance direction of the glass ribbon 3. In addition, striae factors include differences in glass viscosity. When tension is applied in the width direction of the glass ribbon 3 by controlling the cooling amount of the cooling roll 72 by the control unit 91d, locally generated striae, which is a kind of surface irregularity of the glass ribbon 3, is the glass ribbon 3 The glass ribbon is stretched to both end sides 3b to reduce the surface unevenness difference, and a glass ribbon satisfying a thickness tolerance of ± 0.05 mm is formed.

  As described above, by changing the tension T applied to the glass ribbon 3 at the lower end 62a of the molded body 62 in accordance with the displacement L of the molded body 62, the thickness of the central region 3a is changed to the thickness to be molded. The thickness can be made uniform while approaching. When the central portion in the longitudinal direction of the molded body 62 hangs downward and bends due to creep deformation of the molded body 62, the cooling amount of the cooling roll 72 is increased and the tension T applied to the glass ribbon 3 is increased. The thickness deviation in the width direction of the glass ribbon 3 can be reduced. As a result, the glass substrate manufacturing apparatus 1 can reduce the thickness deviation of the glass substrate that is the final product.

  Further, in a glass substrate manufacturing process using glass having a high liquidus temperature and glass having a high strain point, creep deformation of the molded body 62 is particularly problematic because the temperature of the molded body 62 tends to increase. In recent years, the size of the glass substrate has been increased, and the size of the molded body in the longitudinal direction has become longer. Therefore, the bending of the molded body 62 due to creep deformation tends to become more prominent. In the present embodiment, by adjusting the cooling amount of the cooling roll 72 and changing the tension T applied to the glass ribbon 3, the sheet thickness deviation in the width direction of the glass ribbon 3 due to the creep deformation of the molded body 62 is effectively obtained. Can be reduced.

(5-1) Modification A
In the embodiment, the acquisition unit 91b of the control device 91 of the glass substrate manufacturing apparatus 1 acquires shape data related to the current shape of the molded body 62 by obtaining a temporal change in the shape of the molded body 62 by computer simulation. However, the acquisition unit 91b may acquire shape data regarding the current shape of the molded body 62 by another method.

  For example, the acquisition unit 91b may acquire shape data based on an actual measurement value of the shape of the molded body 62. In this case, it is necessary to collect and analyze data related to the actual measurement value of the shape of the molded body 62 and data related to the usage conditions of the molded body 62 in advance. The usage conditions of the molded body 62 are various parameters related to the molded body 62, such as the operating time of the glass substrate manufacturing apparatus 1, the temperature of the molten glass 2, the viscosity of the molten glass 2, and the temperature of the upper molding space 60. is there. The acquisition unit 91b predicts and acquires the shape data of the molded body 62 currently used based on the correlation between the data regarding the actual measurement value of the shape of the molded body 62 and the data regarding the use conditions of the molded body 62. .

  Further, the acquisition unit 91b may acquire shape data based on an actual measurement value of the thickness of the glass ribbon 3 formed by the formed body 62. In this case, the acquisition unit 91b predicts and acquires the shape data of the molded body 62 currently used based on the data regarding the actual measurement value of the thickness of the glass ribbon 3 in the width direction.

(5-2) Modification B
In the embodiment, the cooling amount of the cooling roll 72 is controlled in order to change the tension T applied to the glass ribbon 3. However, instead of the cooling roll 72 or in addition to the cooling roll 72, the tension T can be adjusted by changing the viscosity of the both side portions 3 b of the glass ribbon 3 using a cooling device.

  The cooling device is located, for example, between the lower end 62a of the molded body 62 and the cooling roll 72, and is provided at a position facing the side portion 3b of the glass ribbon 3, and cools both side portions 3b of the glass ribbon 3. Since the controller 91d can control the cooling amount of the both side portions 3b of the glass ribbon 3 by controlling the cooling device, the tension T can be arbitrarily adjusted. Since the cooling device and the glass ribbon 3 are not in direct contact with each other, the tension T can be adjusted by controlling the cooling amount by the cooling device without deforming the glass ribbon 3 by contact.

(5-3) Modification C
In the embodiment, the acquisition unit 91b of the control device 91 of the glass substrate manufacturing apparatus 1 acquires shape data related to the current shape of the molded body 62 by obtaining a temporal change in the shape of the molded body 62 by computer simulation. However, the acquisition unit 91b predicts and acquires the shape data of the molded body 62 currently used by acquiring the total amount (full length) of the glass ribbon 3 molded by the molding apparatus 40 (molded body 62). You can also. For example, the acquisition unit 91b measures the amount of the molten glass 2 flowing into the molding apparatus 40, the thickness, width, weight, and the like of the glass ribbon 3 molded by the molding apparatus 40, thereby forming the glass ribbon molded by the molding apparatus 40. The total amount (full length) of 3 is acquired. Since the total amount (full length) of the glass ribbon 3 and the usage time of the molding device 40 have a positive correlation, the creep of the molding device 40 (molded body 62) is obtained by obtaining the total amount (full length) of the glass ribbon 3. The amount of displacement L due to deformation can be predicted. The controller 91d controls the tension in the width direction of the glass ribbon 3 to be a predetermined reference tension. The predetermined reference tension is an initial value of tension that can satisfy a thickness tolerance of ± 0.05 mm when the glass ribbon 3 (glass substrate) is formed into the glass ribbon 3 having a thickness to be formed. When the displacement amount L is equal to or less than the reference amount, the control unit 91d controls the tension in the width direction of the glass ribbon 3 to be the reference tension. When the displacement amount L exceeds the reference amount, the total amount (total length) of the glass ribbon 3 is controlled. The tension T corresponding to the displacement L due to creep deformation of the molding apparatus 40 (molded body 62) predicted from () is applied to the glass ribbon 3. Thereby, thickness can be made uniform, bringing the thickness of the center area | region 3a of the glass ribbon 3 close to the thickness of shaping | molding schedule.

2 Molten Glass 3 Glass Ribbon 3a Central Region 3b Side 62 Molded Body 62a Lower End 72 Cooling Roll

Claims (10)

The molten glass is supplied to a supply groove formed on the upper surface of the molded body, the molten glass overflowing from both sides of the supply groove is caused to flow down along both side surfaces of the molded body, and the molten glass is flowed down on both side surfaces. A molding step of forming a glass ribbon by joining glass at the lower end of the molded body; and
By cooling both sides in the width direction of the glass ribbon after the forming step, the tension applied in the width direction of the glass ribbon is controlled according to the shape change of the formed body that occurs with the use of the formed body. A method of manufacturing a glass substrate, comprising: a control step. The control step includes
When the shape change is within a preset reference range, the tension applied in the width direction of the glass ribbon is maintained at a reference tension when there is no shape change, and the shape change exceeds the reference range. 2. The method of manufacturing a glass substrate according to claim 1, further comprising: controlling a tension applied in a width direction of the glass ribbon to a tension larger than the reference tension according to a degree of the shape change.   The said shape change is a manufacturing method of the glass substrate of Claim 1 or 2 which is a change from which the said upper surface of the said molded object changes from a plane to a curved surface along the direction where the said supply groove | channel of the said molded object is extended.   In the control step, in addition to the reference tension applied in the width direction of the glass ribbon when the shape does not change in the width direction of the glass ribbon, the tension corresponding to the shape change of the formed body is The manufacturing method of the glass substrate of Claim 1 including applying | hanging on a glass ribbon. An acquisition step of acquiring the amount of vertical displacement of the upper surface of the molded body as information on the shape change;
A determination step of determining whether or not the displacement amount acquired in the acquisition step is equal to or less than a reference amount,
When it is determined in the determination step that the displacement amount exceeds the reference amount, the control step is based on a relational expression between a predetermined displacement amount of the formed body and a tension applied in the width direction of the glass ribbon. The method for manufacturing a glass substrate according to claim 1, wherein a tension corresponding to the obtained displacement amount is determined.   The method for manufacturing a glass substrate according to claim 5, wherein in the control step, the tension is increased as the displacement amount is increased.   The method for manufacturing a glass substrate according to claim 5 or 6, wherein, in the obtaining step, the displacement amount is obtained by obtaining a time change of the shape of the formed body by computer simulation.   The said control process is a manufacturing method of the glass substrate of any one of Claims 1-7 which controls the said tension | tensile_strength so that the plate | board thickness deviation of the thickness direction of the said glass ribbon may become below a reference value. The molten glass is supplied to a supply groove formed on the upper surface of the molded body, the molten glass overflowing from both sides of the supply groove is caused to flow down along both side surfaces of the molded body, and the molten glass is flowed down on both side surfaces. A molding device for forming glass ribbon by joining glass at the lower end of the molded body;
By cooling both sides in the width direction of the glass ribbon after the forming step, the tension applied in the width direction of the glass ribbon is controlled according to the shape change of the formed body that occurs with the use of the formed body. A control device;
An apparatus for producing a glass substrate, comprising:   In the control device, in addition to the reference tension applied in the width direction of the glass ribbon when the shape does not change in the width direction of the glass ribbon, the tension according to the shape change of the formed body is The manufacturing apparatus of the glass substrate of Claim 9 which controls cooling of the both sides of the width direction of the said glass ribbon so that it may put on a glass ribbon.

Images