TW201700416A - Glass-substrate manufacturing method - Google Patents

Abstract

The purpose of the present invention is to provide a glass-substrate manufacturing method with which it is possible to reduce the plate-thickness deviation of a glass substrate. The glass- substrate manufacturing method includes: a molding step; a transporting step; an acquiring step; and a controlling step. In the molding step, molten glass is supplied to a supply groove that is formed on a top surface of a molding body, the molten glass that has overflowed from the supply groove is made to flow down along both of the side surfaces of the molding body, the molten glass that has flowed down along both of the side surfaces is made to join at the bottom end of the molding body, and thus, a glass ribbon is molded. In the transporting step, the glass ribbon is slowly cooled while being transported downward. In the acquiring step, shape data related to the shape of the molding body are acquired. In the controlling step, the temperature profile is controlled on the basis of the shape data by using a temperature-adjusting means installed above the molding body so that the plate-thickness deviation in the width direction of the glass ribbon is reduced. The temperature profile is a profile in the longitudinal direction of the supply groove of the molding body for the temperature of molten glass that comes into contact with the top surface of the molding body.

Description

Method for manufacturing glass substrate

The present invention relates to a method of manufacturing a glass substrate.

Glass substrates for flat panel displays (FPDs, such as liquid crystal displays and plasma displays) require a high degree of flatness on the surface. Usually, such a glass substrate is produced by an overflow down-draw method. In the overflow down-draw method, as described in the patent document 1 (U.S. Patent No. 3,338,696), the molten glass which flows into the groove on the upper surface of the molded body and overflows from the groove flows down along both sides of the formed body, and is formed on the molded body. The lower ends merge to form a glass ribbon. The formed glass ribbon is stretched downward while being cooled. The glass ribbon is obtained by cutting the cooled glass ribbon to a specific size.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] U.S. Patent No. 3,338,696

In the overflow down-draw method, the formed body is placed in a high-temperature atmosphere in the forming furnace. Further, the molded body is subjected to a load based on its own weight and the weight of the molten glass. Therefore, the molded body is gradually creep-deformed according to the thermal creep property of the material of the molded body by the long-term work 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 to be deflected. As a result, there is a problem in that the amount of molten glass overflowing from the central portion of the molded body is higher than that of the molten glass overflowing from both end portions of the molded body. When the amount is large, the thickness of the central portion in the width direction of the formed glass ribbon increases, and the variation in the thickness of the glass substrate as the final product increases.

When the variation in the thickness of the glass substrate is large, not only the variation in the thickness of one glass substrate is large, but also the variation in thickness between the plurality of glass substrates is large, and the quality of the glass substrate is unstable. In the manufacturing process of the panel for a display, the variation in the thickness of one glass substrate may be corrected by the correction of the pattern shape of a TFT (Thin Film Transistor) wiring or the like. However, the variation in the thickness between the plurality of glass substrates is difficult to cope with by the correction of the pattern shape. Further, since a glass substrate for a high-definition display is formed with a pattern which is thinner and higher in density than before, there is a product variation even if the glass substrate for the prior display is not considered to be a problem. Quality is a problem.

Further, in the production step of using a glass substrate having a glass having a high liquidus temperature and a glass having a high strain point, the creep deformation of the molded body is particularly problematic because the temperature of the molded body is likely to become high. In addition, in recent years, the size of the glass substrate has been increased, and the dimension in the longitudinal direction of the molded article has been increased to more than 3,000 mm. Therefore, the deflection of the molded body due to creep deformation tends to be more remarkable.

Accordingly, an object of the present invention is to provide a method for producing a glass substrate which can reduce variation in thickness of a glass substrate.

The method for producing a glass substrate of the present invention includes a molding step, a transfer step, an acquisition step, and a control step. The forming step supplies the molten glass to the supply grooves formed on the upper surface of the molded body, so that the molten glass overflowing from the supply grooves flows down the both sides of the molded body, and the molten glass flowing down the both sides merges at the lower end of the formed body. And forming a glass ribbon. In the transfer step, the glass ribbon formed in the forming step is conveyed downward while being cooled. The obtaining step acquires shape data related to the shape of the formed body. The control step is based on the shape data obtained in the obtaining step, and the plate pressure deviation in the width direction of the glass ribbon is reduced. In the manner, the temperature distribution is controlled using a temperature adjustment mechanism provided above the molded body. The temperature distribution is a distribution in the longitudinal direction of the supply groove of the molded body at the temperature of the molten glass in contact with the upper surface of the molded body.

Further, in the method for producing a glass substrate of the present invention, the obtaining step is preferably to obtain shape data based on creep deformation of the molded body.

Further, in the method for producing a glass substrate of the present invention, the obtaining step preferably takes at least the displacement amount in the vertical direction of the upper surface of the molded body as the shape data. In this case, the control step preferably controls the temperature distribution according to the distribution of the displacement amount in the longitudinal direction, that is, the shape distribution.

Further, in the method for producing a glass substrate of the present invention, the control step preferably controls the temperature distribution such that the larger the displacement amount of the shape distribution is, the higher the temperature of the corresponding temperature distribution is.

Further, in the method for producing a glass substrate of the present invention, the obtaining step preferably acquires the shape data by obtaining a temporal change in the shape by computer simulation.

Further, in the method for producing a glass substrate of the present invention, it is preferable that the obtaining step acquires the shape data based on the thickness of the glass substrate which is conveyed downward and is cold-cooled in the transporting step.

Further, in the method for producing a glass substrate of the present invention, the temperature adjustment mechanism preferably has a plurality of heat generating bodies provided along the longitudinal direction.

Further, in the method for producing a glass substrate of the present invention, the heating element preferably has a rod-shaped ceramic heater having a space in which a fluid for cooling flows and having a rod shape extending in a direction orthogonal to the longitudinal direction.

The method for producing a glass substrate of the present invention can reduce the variation in thickness of the glass substrate.

1‧‧‧Glass substrate manufacturing equipment

2‧‧‧Solid glass

3‧‧‧glass ribbon

10‧‧‧melting tank

20‧‧‧clarification tube

30‧‧‧Agitator

40‧‧‧Forming device

42‧‧‧ furnace wall

44‧‧‧ top board

46‧‧‧ Upper temperature control space

48‧‧‧heating body

48a‧‧‧Cooling path

50a‧‧‧Transfer tube

50b‧‧‧Transfer tube

50c‧‧‧Transfer tube

60‧‧‧Upper forming space

62‧‧‧Formed body

62a‧‧‧Bottom

62b‧‧‧ supply slot

62c‧‧‧ upper surface

62d1‧‧‧1st end

62d2‧‧‧2nd end

64‧‧‧ upper spacer

70‧‧‧ Lower forming space

72‧‧‧Cooling roller

74‧‧‧temperature adjustment unit

74a‧‧‧Central cooling unit

74b‧‧‧Side cooling unit

76‧‧‧ Lower spacers

80‧‧‧Xu cold space

82a~82g‧‧‧ Pull down roller

84a~84g‧‧‧heater

86‧‧‧Insulation members

91‧‧‧Control device

98‧‧‧cutting device

172‧‧‧Cooling roller drive motor

182‧‧‧ Pull-down roller drive motor

198‧‧‧cutting device drive motor

L‧‧‧Maximum upper surface displacement

S1‧‧‧ melting step

S2‧‧‧Clarification steps

S3‧‧‧ stirring step

S4‧‧‧ forming steps

S5‧‧‧ Cooling step

S6‧‧‧ cutting step

Fig. 1 is a flow chart showing a method of manufacturing a glass substrate of an embodiment.

Fig. 2 is a schematic view showing a manufacturing apparatus of a glass substrate.

Figure 3 is a front view of the forming apparatus.

Figure 4 is a side view of the forming apparatus.

Figure 5 is a front elevational view of the vicinity of the forming space of the upper portion of the forming apparatus.

Figure 6 is a side view of the vicinity of the upper forming space of the forming apparatus.

Figure 7 is a block diagram of the control device.

Fig. 8 is an example of shape data of a molded body obtained by the acquisition unit.

Fig. 9 is an example of a graph showing a strain rate of a molded body depending on a change in temperature.

Fig. 10 is an example of a graph in which the strain rate of the formed body depends on the change in stress.

(1) Composition of a manufacturing apparatus for a glass substrate

Embodiments of the method for producing a glass substrate of the present invention will be described with reference to the drawings. Fig. 1 is a flow chart showing an example of a method of producing a glass substrate of the present embodiment.

As shown in FIG. 1, the manufacturing method of the glass substrate of this embodiment mainly includes a melting step S1, a clarification step S2, a stirring step S3, a molding step S4, a cooling step S5, and a cutting step S6.

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 is electrically heated to have a desired temperature. A clarifying agent is added to the glass raw material. From the viewpoint of reducing environmental load, SnO _{2 is} used as a clarifying agent.

In the clarification step S2, the molten glass obtained in the melting step S1 flows inside the clarification pipe to remove the gas contained in the molten glass, thereby clarifying the molten glass. First, in the clarification step S2, the temperature of the molten glass is raised. The clarifying agent added to the molten glass releases oxygen by a temperature reduction causing a reduction reaction. The bubbles containing gas components such as CO ₂ , N ₂ , and SO ₂ contained in the molten glass absorb oxygen generated by a reduction reaction of a fining agent. The bubble that absorbs oxygen and rises up to the surface of the molten glass, and ruptures and disappears. The gas system contained in the disappearing bubble is released into the gas phase space inside the clarification pipe and discharged to the outside atmosphere. Next, in the clarification step S2, the temperature of the molten glass is lowered. Thereby, the reduced clarifying agent causes an oxidation reaction to absorb a gas component such as oxygen remaining in the molten glass.

In the stirring step S3, the molten glass which has been removed in the clarification step S2 is stirred to homogenize the components of the molten glass. Thereby, the unevenness of the composition of the molten glass which is a cause of the pulse of a glass substrate etc. is reduced.

In the forming step S4, the glass ribbon is continuously formed from the molten glass homogenized in the stirring step S3 by using the overflow down-draw method.

In the cooling step S5, the glass ribbon formed in the forming step S4 is conveyed downward while being cooled. 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 strained or warped.

In the cutting step S6, the glass ribbon cooled in the cooling step S5 is cut into a specific size to obtain a glass substrate. Thereafter, grinding and polishing of the end surface of the glass substrate and cleaning of the glass substrate are performed. Thereafter, the presence or absence of defects such as scratches on the glass substrate is checked, and the glass substrate which has passed the inspection is bundled and shipped as a product.

Fig. 2 is a schematic view showing an example of the glass substrate manufacturing apparatus 1 of the embodiment. The glass substrate manufacturing apparatus 1 includes a melting tank 10, a clarification pipe 20, a stirring device 30, a molding device 40, and transfer pipes 50a, 50b, and 50c. The transfer pipe 50a connects the melting tank 10 to the clarification pipe 20. The transfer pipe 50b connects the clarification pipe 20 to the stirring device 30. The transfer pipe 50c connects the stirring device 30 to the forming device 40.

The molten glass 2 obtained in the melting tank 10 in the melting step S1 flows into the clarification pipe 20 through the transfer pipe 50a. The molten glass 2 which has been clarified in the clarification pipe 20 in the clarification step S2 flows into the stirring device 30 through the transfer pipe 50b. The molten glass 2 stirred in the stirring device 30 in the stirring step S3 flows into the forming device 40 through the transfer pipe 50c. In the forming step S4, the glass ribbon 3 is continuously formed from the molten glass 2 by the forming device 40. Cooling step In step S5, the glass ribbon 3 is conveyed downward while being cooled. In the cutting step S6, the cooled glass ribbon 3 is cut into a specific 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 produced 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, or an organic EL (electroluminescence) display. As the glass substrate for FPD, an alkali-free glass, a glass containing a small amount of alkali, a glass for low-temperature polycrystalline silicon (LTPS), or a glass for an oxide semiconductor is used. As a glass substrate for high-definition displays, it is used for glass having high viscosity and high strain point at high temperatures. For example, a glass which is a raw material of a glass substrate for a high-definition display has a viscosity of 10 ^2.5 poise at 1500 °C.

In the melting tank 10, the glass raw material is melted to obtain molten glass 2. The glass raw material is prepared in such a manner that a glass substrate having a desired composition can be obtained. As an example of the composition of the glass substrate, the alkali-free glass which is preferably a glass substrate for FPD contains SiO ₂ : 50% by mass to 70% by mass, Al ₂ O ₃ : 10% by mass to 25% by mass, and B ₂ O ₃ : 1 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, and 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.

Further, as the glass substrate for FPD, a glass containing a small amount of alkali may be used, and the glass contains a trace amount of an alkali metal. The glass containing a trace amount of alkali contains 0.1% by mass to 0.5% by mass of R' ₂ O, preferably 0.2% by mass to 0.5% by mass of R' ₂ O. Here, R' is at least one selected from the group consisting of Li, Na, and K. The total content of R' ₂ O may not be as much as 0.1% by mass.

Further, the glass substrate produced by the glass substrate manufacturing apparatus 1 may further contain SnO ₂ : 0.01% by mass to 1% by mass (preferably 0.01% by mass to 0.5% by mass), and Fe ₂ O ₃ : 0% by mass to 0.2%. % by mass (preferably 0.01% by mass to 0.08% by mass). Further, from the viewpoint of reducing the environmental load, the glass substrate produced by the glass substrate manufacturing apparatus 1 does not substantially contain As ₂ O ₃ , Sb ₂ O ₃ and PbO.

The glass raw material prepared in the above-described composition is supplied to the melting tank 10 using a raw material dispenser (not shown). The raw material input machine can use a screw feeder to input glass raw materials, and a bucket can also be used to input glass raw materials. In the melting tank 10, the glass raw material is heated to a temperature corresponding to its composition and the like to be melted. In the melting tank 10, for example, a molten glass 2 having a high temperature of 1500 ° C to 1600 ° C is obtained. In the melting tank 10, the molten glass 2 between the electrodes can be electrically heated by a current flowing between at least one pair of electrodes formed by molybdenum, platinum, or tin oxide, or by a burner. The glass material is heated in a flame-assisted manner.

The molten glass 2 obtained in the melting tank 10 flows into the clarification pipe 20 through the transfer pipe 50a from the melting tank 10. The clarification pipe 20 and the transfer pipes 50a, 50b, and 50c are pipes made of platinum or platinum alloy. In the clarification pipe 20, a heating device is provided in the same manner as the melting tank 10. In the clarification pipe 20, the molten glass 2 is further heated and clarified. For example, in the clarification pipe 20, the temperature of the molten glass 2 rises to 1500 ° C to 1700 ° C.

The molten glass 2 clarified in the clarification pipe 20 flows from the clarification pipe 20 through the transfer pipe 50b to the stirring device 30. The molten glass 2 is cooled while passing through the transfer pipe 50b. In the stirring device 30, the molten glass 2 is stirred at a temperature lower than the temperature of the molten glass 2 passing through the clarification pipe 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 homogenized by stirring in the stirring device 30.

The molten glass 2 which has been homogenized in the stirring device 30 flows into the forming device 40 from the stirring device 30 through the transfer pipe 50c. The molten glass 2 is cooled so as to have a viscosity suitable for the formation of the molten glass 2 when passing through the transfer pipe 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 an overflow down-draw method. Next, the detailed configuration and operation of the molding apparatus 40 will be described.

(2) Composition of the forming device

3 is a front view of the forming device 40. 3 shows the forming device 40 as viewed in a direction perpendicular to the surface of the glass ribbon 3 formed by the forming device 40. 4 is a side view of the forming device 40. 4 shows the resulting forming apparatus 40 as viewed in 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 42 made of a refractory such as 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. The space includes three spaces of the upper forming space 60, the lower forming space 70, and the undercooling space 80. Figure 5 is a front elevational view of the vicinity of the upper forming space 60 of the forming apparatus 40. Fig. 6 is a side view of the vicinity of the upper forming space 60 of the forming device 40.

The forming step S4 is performed in the upper forming space 60. The cooling step S5 is performed in the lower forming space 70 and the quenching 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 50c is formed into the glass ribbon 3. The lower forming space 70 is a space below the upper forming space 60, and is a space in which the glass ribbon 3 is quenched to a point near the cold spot of the glass. The space below the lower forming space 70 of the X-Cold space 80 is the space in which the glass ribbon 3 is gradually cooled.

The molding apparatus 40 mainly includes a molded body 62, a plurality of heat generating bodies 48, an upper partitioning member 64, a cooling roller 72, a temperature adjusting unit 74, a lower partitioning member 76, pull-down rollers 82a to 82g, heaters 84a to 84g, and a heat insulating member 86. The cutting device 98 and the control device 91. Next, each component of the molding apparatus 40 will be described.

(2-1) Shaped body

The formed body 62 is provided in the upper forming space 60. The molded body 62 is for overflowing the molten glass 2 to form the glass ribbon 3. As shown in Fig. 4, the formed body 62 has a cross-sectional shape similar to a wedge-shaped pentagon. The tip end of the cross-sectional shape of the formed body 62 corresponds to the lower end 62a of the formed body 62. The formed body 62 is made of refractory brick.

On the upper surface 62c of the molded body 62, a supply is formed along the longitudinal direction of the molded body 62. Slot 62b. A transfer pipe 50c that communicates with the supply groove 62b is attached to an end portion of the molded body 62 in the longitudinal direction. The supply groove 62b is formed to gradually become shallower as it goes from one end to the other end of the transfer tube 50c. Hereinafter, as shown in FIG. 3, the end portion of the one end portion of the longitudinal direction of the molded body 62 that communicates with the transfer pipe 50c is referred to as a first end portion 62d1, and the end portion on the opposite side is referred to as a first portion. 2 end 62d2. Further, a platinum guide (not shown) for blocking the flow of the molten glass 2 in the supply tank 62b is provided in the second end portion 62d2 of the molded body 62.

The molten glass 2 sent from the stirring device 30 to the molding device 40 flows into the supply groove 62b of the molded body 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 overflowing from the supply groove 62b of the molded body 62 flows down the both sides of the molded body 62, and merges in the vicinity of the lower end 62a of the molded body 62. The molten glass 2 after the joining is formed into a plate shape by dropping in the vertical direction by gravity. Thereby, the glass ribbon 3 is continuously formed in the vicinity of the lower end 62a of the molded body 62. The formed glass ribbon 3 flows down the upper molding space 60, and is cooled while being cooled in the lower molding space 70 and the cold space 80, and is conveyed downward. The glass ribbon 3 just after the upper forming space 60 is formed has a temperature of 1100 ° C or more and a viscosity of 25,000 poise to 350,000 poise. For example, in the case of 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, at the lower end of the molded body 62. The viscosity of the molten glass 2 fused in the vicinity of 62a is 25,000 poises to 100,000 poises, preferably 32,000 poises to 80,000 poises.

(2-2) Heating element

As shown in FIGS. 5 and 6, a top plate 44 is provided above the molded body 62. The top plate 44 is a plate-like member containing tantalum carbide. The top plate 44 is fixed to the furnace wall 42. The top plate 44 divides the upper upper temperature control space 46 of the top plate 44 and the lower upper forming space 60 of the top plate 44. The upper temperature control space 46 is a space surrounded by the furnace wall 42 and the top plate 44. As shown in FIG. 5, in the upper temperature control space 46, plural numbers are arranged at equal intervals along the longitudinal direction of the molded body 62. Heating element 48.

The heating element 48 is a porous ceramic heater containing niobium carbide. The heating element 48 is a rod-shaped member that generates heat by energization. As shown in FIG. 6, the heating element 48 is arranged along a direction orthogonal to the longitudinal direction of the molded body 62 and orthogonal to the vertical direction. Each of the heating elements 48 is connected to an individual power source, and the output of each heating element 48 can be individually controlled. The heating element 48 heats the top plate 44 by radiation. The top plate 44 heated by the heating element 48 heats the molten glass 2 that is in contact with the upper surface 62c of the formed body 62 by radiation.

As shown in FIGS. 5 and 6, the heating element 48 has a cooling passage 48a therein. The cooling passage 48a is formed along the longitudinal direction of the heating element 48. The cooling passage 48a is a space in which a fluid for cooling the heating element 48, that is, a cooling fluid flows. The cooling fluid is, for example, air. The cooling passage 48a of each heating element 48 is connected to an individual cooling fluid supply device, and the flow rate of the cooling fluid in the cooling passage 48a can be individually controlled. In the case where the cooling fluid is air, the cooling fluid supply device is an air pump. In addition, from the viewpoint of suppressing deterioration due to oxidation of the furnace wall 42, the top plate 44, and the heat generating body 48, etc., when the glass substrate manufacturing apparatus 1 is operated for a long period of three years or more, it is preferable to use nitrogen gas. An inert gas is used as the cooling fluid.

The control device 91 can control the amount of heat radiated from the heating element 48 by controlling the output of the heating element 48 and the flow rate of the cooling fluid in the cooling passage 48a of the heating element 48. The control device 91 can adjust the temperature of the top plate 44 by increasing the output of the heating element 48 or reducing the flow rate of the cooling fluid in the cooling passage 48a to increase the radiant heat of the heating element 48. Further, the control device 91 can adjust the temperature of the top plate 44 by reducing the output of the heat generating body 48 or increasing the flow rate of the cooling fluid in the cooling passage 48a to reduce the radiant heat of the heat generating body 48. Further, by stopping the output of the heating element 48 and increasing the flow rate of the cooling fluid in the cooling passage 48a, the temperature of the atmosphere in the vicinity of the heating element 48 can be lowered, and the temperature of the top plate 44 can be adjusted by convective heat conduction. The control device 91 manages the temperature distribution of the top plate 44 by individually controlling the radiant heat of each of the heat generating bodies 48 and individually adjusting the flow rate of the cooling fluid in the cooling passage 48a. The temperature distribution of the molten glass 2 which is in contact with the upper surface 62c of the formed body 62, which receives the radiant heat from the top plate 44, is controlled. The temperature distribution is a temperature distribution in the longitudinal direction of the formed body 62.

(2-3) Upper spacer member

The upper partition member 64 is a pair of plate-shaped heat insulating members provided in the vicinity of the lower end 62a of the molded body 62. As shown in FIG. 4, the upper partition members 64 are disposed on both sides in the thickness direction of the glass ribbon 3. The upper partition member 64 spaces the upper forming space 60 from the lower forming space 70, and suppresses the movement of heat from the upper forming space 60 to the lower forming space 70.

(2-4) Cooling roller

The cooling roller 72 is a cantilever roller that is disposed in the lower forming space 70. The cooling roller 72 is disposed directly under the upper partition member 64. As shown in FIG. 3, the cooling roll 72 is arrange|positioned in the both sides of the width direction of the glass ribbon 3. As shown in FIG. 4, the cooling rolls 72 are disposed on both sides in the thickness direction of the glass ribbon 3. The glass ribbon 3 is held by the cooling roller 72 at both side portions in the width direction. The cooling roll 72 cools the glass ribbon 3 sent from the upper forming space 60.

In the lower molding space 70, both side portions in the width direction of the glass ribbon 3 are sandwiched by two pairs of cooling rolls 72. By pressing the cooling rolls 72 toward the surfaces of both side portions of the glass ribbon 3, the contact area between the cooling rolls 72 and the glass ribbon 3 is increased, and the glass ribbon 3 is cooled by the cooling rolls 72 efficiently. The cooling roller 72 applies a force to the glass ribbon 3 against the downward pulling force of the lower rollers 82a to 82g to pull the glass ribbon 3 downward. Further, the thickness of the glass ribbon 3 is determined by the difference between the rotational speed of the cooling roller 72 and the rotational speed of the uppermost lower pulling roller 82a.

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

The contact load between the chill roll 72 and the glass ribbon 3 can be controlled by the control device 91. contact The load is controlled, for example, by adjusting the position of the cooling roller 72 using a spring. The greater the contact load, the stronger the force of the chill roll 72 against the glass ribbon 3.

(2-5) Temperature adjustment unit

The temperature adjustment unit 74 is disposed in the lower forming space 70. The temperature adjustment unit 74 is disposed below the upper spacing member 64 and above the lower spacing member 76.

In the lower molding space 70, the glass ribbon 3 is cooled until the temperature of the center portion in the width direction of the glass ribbon 3 is lowered to the vicinity of the cold spot. The temperature adjusting 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 center portion cooling unit 74a and a side portion cooling unit 74b. The center portion cooling unit 74a adjusts the temperature of the center portion of the glass ribbon 3 in the width direction. The side cooling unit 74b adjusts the temperature of both side portions in the width direction of the glass ribbon 3. Here, the center portion in the width direction of the glass ribbon 3 refers to a region sandwiched between both side portions in the width direction of the glass ribbon 3.

As shown in FIG. 3, in the lower molding space 70, a plurality of central portion cooling units 74a and a plurality of side cooling units 74b are disposed in a vertical direction, that is, a direction in which the glass ribbon 3 flows downward. The center portion cooling unit 74a is disposed to face the surface of the center portion in the width direction of the glass ribbon 3. The side cooling unit 74b is disposed to face the surfaces of both side portions in the width direction of the glass ribbon 3.

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

(2-6) lower spacer member

The lower partition member 76 is provided in a pair of plate-shaped heat insulating members below the temperature adjusting unit 74. As shown in FIG. 4, the lower partition members 76 are provided on both sides in the thickness direction of the glass ribbon 3. The lower partition member 76 spaces the lower forming space 70 from the cold space 80 in the vertical direction, and suppresses the movement of heat from the lower forming space 70 to the cold space 80.

(2-7) pull-down roller

The pull-down rolls 82a to 82g are cantilever rolls provided in the cold space 80. In the Xu cold space 80, a pull-down roller 82a, a pull-down roller 82b, ..., a pull-down roller 82f, and a pull-down roller 82g are disposed at intervals from the upper side toward the lower side. The pull-down roller 82a is disposed at the uppermost position, and the pull-down roller 82g is disposed at the lowest position.

As shown in FIG. 3, the pull-down rolls 82a-82g are respectively arrange|positioned in the both sides of the width direction of the glass ribbon 3. As shown in FIG. 4, the pull-down rolls 82a to 82g are respectively disposed on both sides in the thickness direction of the glass ribbon 3. In other words, the both side portions in the width direction of the glass ribbon 3 are sandwiched by the pair of pull-down rollers 82a, 2, the pair of pull-down rollers 82b, ..., 2, the pair of pull-down rollers 82f, and the pair of pull-down rollers 82g from the upper side toward the lower side.

The pull-down rolls 82a to 82g are rotated while sandwiching the both end portions of the glass ribbon 3 passing through the lower molding space 70 in the width direction, thereby pulling the glass ribbon 3 downward in the vertical direction. That is, the pull-down rolls 82a to 82g are rollers for conveying the glass ribbon 3 downward.

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

(2-8) heater

The heaters 84a to 84g are provided in the cold space 80. As shown in Fig. 4, in the cold space 80, a heater 84a, a heater 84b, ..., a heater 84f, and a heater 84g are disposed at intervals from above. The heaters 84a to 84g are disposed on both sides in the thickness direction of the glass ribbon 3, respectively. The pull-down rolls 82a to 82g are disposed between the heaters 84a to 84g and the glass ribbon 3, respectively.

The heaters 84a to 84g 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 cold space 80 can be adjusted. Thereby, the heaters 84a to 84g can form a specific temperature distribution in the glass ribbon 3 in the conveying direction of the glass ribbon 3.

The outputs of the heaters 84a-84g can be independently controlled by the control unit 91. Further, the heaters 84a to 84g may be divided into a plurality of heating along the width direction of the glass ribbon 3. The sub-units (not shown), and the outputs of the sub-units of the heaters can be independently controlled by the control unit 91. In this case, each of the heaters 84a to 84g can form a specific temperature distribution in the width direction of the glass ribbon 3 by changing the amount of heat generation according to the position in the width direction of the glass ribbon 3.

Further, a thermocouple (not shown) for measuring the temperature of the atmosphere of the quenching space 80 is provided in the vicinity of each of the heaters 84a to 84g. The thermocouple measures, for example, the ambient temperature in the vicinity of the center portion in the width direction of the glass ribbon 3 and the ambient temperature in the vicinity of both side portions. The heaters 84a to 84g can also be controlled according to the temperature of the atmosphere of the cold space 80 measured by the thermocouple.

(2-9) Insulation member

The heat insulating member 86 is disposed in the cold space 80. The heat insulating member 86 is disposed at a height position between the two pull-down rolls 82a to 82g adjacent to each other in the conveyance direction of the glass ribbon 3. As shown in FIG. 4, the heat insulating member 86 is disposed horizontally on one of the two sides of the glass ribbon 3 in the thickness direction. The heat insulating member 86 spaces the cold space 80 in the vertical direction, and suppresses the movement of heat in the vertical direction in the cold space 80.

The heat insulating member 86 is provided so as not to be in contact with the glass ribbon 3 that is transported downward. Further, the heat insulating member 86 is provided to be adjustable to the distance from the surface of the glass ribbon 3. 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.

(2-10) cutting device

The cutting device 98 is disposed in a space below the cold space 80. The cutting device 98 cuts the glass ribbon 3 passing through the cold space 80 at a specific dimension along the width direction of the glass ribbon 3. The glass ribbon 3 of the cold space 80 is cooled to a flat glass ribbon 3 near room temperature.

The cutting device 98 cuts the glass ribbon 3 at specific time intervals. Thereby, when the conveying speed of the glass ribbon 3 is fixed, the glass substrate which has the size similar to a final product is mass-produced.

(2-11) Control device

The control device 91 mainly includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk. FIG. 7 is a block diagram of the control device 91. As shown in FIG. 7, the control device 91 is connected to the cooling roller drive motor 172, the temperature adjustment unit 74, the pull-down roller drive motor 182, the heaters 84a to 84g, the heating element 48, and the cutting device drive motor 198. The cooling roller drive motor 172 is a motor for controlling the position and rotational speed of the cooling roller 72. The pull-down roller drive motor 182 is a motor for independently controlling the position and rotational speed of each of the pull-down rollers 82a to 82g. The cutting device drive motor 198 is a motor for controlling the time interval in which the cutting device 98 cuts the glass ribbon 3 or the like. The control device 91 stores a program for obtaining the state of each component and controlling each component.

The control device 91 can control the cooling roller drive motor 172 to acquire and adjust the contact load between one of the side portions sandwiching the width direction of the glass ribbon 3 and the cooling roller 72 and the glass ribbon 3. The control device 91 can control the pull-down roller drive motor 182 to obtain the torque of each of the rotating pull-down rollers 82a to 82g and adjust the angular velocities of the respective pull-down rollers 82a to 82g. The control unit 91 can acquire and adjust the output of the temperature adjustment unit 74 and the outputs of the heaters 84a to 84g. The control device 91 individually controls the radiant heat of each of the heat generating bodies 48. The control device 91 can control the cutting device drive motor 198 to acquire and adjust the time interval at which the cutting device 98 cuts the glass ribbon 3, and the like.

(3) Action of the forming 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 is supplied to the supply groove 62b formed on the upper surface 62c of the molded body 62. The molten glass 2 overflowing from the supply groove 62b of the molded body 62 flows down the both sides of the molded body 62, and merges in the vicinity of the lower end 62a 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 after the joining. The formed glass ribbon 3 is sent to the lower forming space 70.

In the lower molding space 70, both side portions in the width direction of the glass ribbon 3 are brought into contact with the cooling roller 72 to be quenched. Moreover, the temperature of the glass ribbon 3 is adjusted by the temperature adjusting unit 74. The temperature in the center portion in the width direction of the glass ribbon 3 is lowered to the point of freezing. The glass ribbon 3 which is conveyed downward by the cooling roller 72 and cooled while being cooled is sent to the cold space 80.

In the cold space 80, the glass ribbon 3 is pulled down by the pull-down rolls 82a to 82g, and gradually cooled. The temperature of the glass ribbon 3 is controlled by the heaters 84a to 84g so as to form a specific temperature distribution along the width direction of the glass ribbon 3. In the cold space 80, the temperature of the glass ribbon 3 gradually decreases from the vicinity of the cold point to a temperature lower than the temperature lower than the strain point by 200 °C.

The glass ribbon 3 of the cold space 80 is further cooled to near room temperature, and is cut into a specific size by the cutting device 98 to obtain a glass substrate. Thereafter, polishing, cleaning, and the like of the end faces of the glass substrate are performed. Then, the glass substrate which has passed the specific inspection is bundled and shipped as a product.

(4) Action of the control device

The control device 91 stores and executes at least three programs including a transport unit, an acquisition unit, and a control unit.

In the conveyance unit, the glass ribbons 3 formed by the molded body 62 are conveyed downward at a specific conveyance speed by using the lower rolls 82a to 82g provided below the molded body 62. The conveyance unit controls the pull-down roller drive motor 182 to adjust the rotation speed of each of the pull-down rollers 82a to 82g, thereby adjusting the conveyance speed of the glass ribbon 3.

The acquisition unit acquires shape data relating to the current shape of the molded body 62 by temporally changing the shape of the molded body 62 by computer simulation. The acquisition unit obtains shape data by, for example, obtaining a time change of the shape of the molded body 62 by simulation using a finite element method. Fig. 8 is an example of the shape data of the molded body 62 obtained by the acquisition unit. Fig. 8 shows the obtained molded body 62 as viewed in a direction perpendicular to the surface of the glass ribbon 3 formed by the formed body 62. In Fig. 8, the creep deformation of the formed body 62 is emphasized in comparison with the actual one. In Fig. 8, the shape of the unused molded body 62, that is, the shape of the molded body 62 before creep deformation, is indicated by a broken line, and the current shape of the molded body 62 after creep deformation is indicated by a solid line. shape.

The acquisition unit obtains at least the amount of displacement in the vertical direction of the upper surface 62c of the molded body 62, that is, the amount of displacement of the upper surface, from the shape data based on the creep deformation of the molded body 62. In Fig. 8, the upper surface displacement amount is the dimension in the vertical direction between the upper surface 62c before the creep deformation and the upper surface 62c after the creep deformation. In addition, FIG. 8 shows the maximum upper surface displacement amount L which is the maximum value of the surface displacement amount in the longitudinal direction of the molded body 62.

Moreover, the acquisition unit acquires the thickness data of the glass substrate measured by the glass substrate shape measuring device (not shown). The thickness data is, for example, a distribution in the width direction of the thickness of the glass substrate produced by the glass substrate manufacturing apparatus 1.

The control unit individually controls the radiant heat of each of the heat generating elements 48 and the respective heat generating bodies 48 so that the variation in the thickness of the glass ribbon 3 in the width direction is small, based on the shape data of the molded body 62 obtained by the acquiring unit. The flow rate of the cooling fluid in the cooling passage 48a is controlled to control the temperature distribution of the molten glass 2 which is in contact with the upper surface 62c of the formed body 62. The shape data of the molded body 62 is, for example, a distribution of the surface displacement amount in the longitudinal direction of the molded body 62, that is, a shape distribution. The control unit controls the heating element 48 such that the temperature of the first end portion 62d1 of the temperature distribution becomes lower as the displacement amount of the upper surface 62c is larger, and the temperature distribution is higher. The temperature in the central part becomes a higher value. As the displacement amount of the upper surface 62c obtained from the shape distribution, for example, the maximum upper surface displacement amount L is used.

When the temperature of the first end portion 62d1 of the temperature distribution of the molten glass 2 is lowered, the temperature of the molten glass 2 in the supply groove 62b of the first end portion 62d1 is lowered. Therefore, the molten glass of the supply groove 62b of the first end portion 62d1 is lowered. The viscosity of 2 increases. When the viscosity of the molten glass 2 overflowing from the supply tank 62b rises, the thickness of the molten glass 2 flowing down along both sides of the molded body 62 becomes large, and therefore the thickness of the glass ribbon 3 formed at the lower end 62a of the molded body 62 also changes. Big. Therefore, when the radiant heat of the heating element 48 is controlled and the temperature of the first end portion 62d1 of the temperature distribution of the molten glass 2 is lowered, the thickness of the first end portion 62d1 side of the glass ribbon 3 becomes large.

Further, if the temperature of the central portion of the temperature distribution of the molten glass 2 becomes high, the width direction Since the temperature of the molten glass 2 of the supply groove 62b of the center part rises, the viscosity of the molten glass 2 of the supply groove 62b of the center part of the width direction falls. In this way, the viscosity of the molten glass 2 in the center portion in the width direction of the supply groove 62b is lowered. Therefore, in the supply groove 62b, the molten glass 2 easily flows from the central portion in the width direction toward the second end portion 62d2. As a result, the amount of the molten glass 2 flowing toward the second end portion 62d2 increases, and the amount of the molten glass 2 overflowing from the second end portion 62d2 of the supply groove 62b increases, so that the second end portion 62d2 side of the glass ribbon 3 is increased. The thickness becomes larger. In addition, the viscosity of the molten glass 2 in the supply groove 62b at the center portion in the width direction is lowered, and the thickness of the central portion in the width direction of the glass ribbon 3 is reduced.

Therefore, by controlling the temperature distribution of the molten glass 2 which is in contact with the upper surface 62c of the molded body 62 as described above, the thickness of the central portion in the width direction of the glass ribbon 3 can be made small and both ends in the width direction of the glass ribbon 3 can be made. The thickness becomes larger.

The control unit 91 can reduce the variation in the thickness of the glass ribbon 3 conveyed downward in the cold space 80 by the conveyance unit, the acquisition unit, and the control unit as described below.

(5) Features

In the present embodiment, the molded body 62 is provided in an atmosphere of a high temperature in the upper molding space 60. In the molding step of the glass ribbon 3, the weight of the molded body 62 and the weight of the molten glass 2 supplied to the supply tank 62b are applied to the molded body 62. Therefore, the molded body 62 gradually creeps and deforms according to the thermal creep property of the material of the molded body 62 as shown in FIG. 8 due to the long-term operation of the glass substrate manufacturing apparatus 1. In particular, the central portion of the molded body 62 in the longitudinal direction is likely to sag downward due to creep deformation and to be deflected. In FIG. 8, the maximum upper surface displacement amount L is the amount of surface displacement above the central portion in the longitudinal direction of the molded body 62.

When the molded body 62 is creep-deformed as shown in FIG. 8, the amount of the molten glass 2 overflowing from the center portion in the longitudinal direction of the molded body 62 is larger than that of the molten glass 2 overflowing from both end portions in the longitudinal direction of the molded body 62. More quantity. In this case, the thickness of the central portion in the width direction of the glass ribbon 3 formed by the molded body 62 is larger than the thickness of both end portions in the width direction. As a result, the variation in the thickness of the glass ribbon 3 in the width direction is large, and the thickness deviation of the glass substrate as the final product is large. Increase the number. In particular, the larger the maximum upper surface displacement amount L is, the greater the degree of creep deformation of the molded body 62 is. Therefore, the variation in the thickness of the glass ribbon 3 in the width direction is also large.

In the glass substrate manufacturing apparatus 1 of the present embodiment, the temperature distribution in order to reduce the variation in the thickness of the glass substrate in the width direction is calculated based on the shape data of the molded body 62 and the thickness data of the glass substrate. The temperature distribution is a temperature distribution of the molten glass 2 which is in contact with the upper surface 62c of the formed body 62. Further, the glass substrate manufacturing apparatus 1 individually controls the radiant heat of each of the heat generating bodies 48 and the flow rate of the cooling fluid in the cooling passages 48a of the heat generating bodies 48 based on the calculated temperature distribution, thereby realizing the calculated temperature distribution. The thickness deviation in the width direction of the glass ribbon 3 due to the creep deformation of the molded body 62 can be reduced. Further, after the glass substrate manufacturing apparatus 1 realizes the calculated temperature distribution, the thickness data of the glass substrate can be acquired again, and based on the obtained thickness data, it is further calculated to reduce the variation in the thickness direction of the glass substrate in the width direction. Good temperature distribution.

Next, the reason why the variation in the thickness of the glass ribbon 3 in the width direction is reduced by the control of the temperature distribution of the molten glass 2 will be described. First, the acquisition portion of the control device 91 of the glass substrate manufacturing apparatus 1 acquires a shape distribution which is one of the shape data relating to the current shape of the creep-deformed molded body 62 shown in FIG. Further, the acquisition unit acquires the thickness data of the glass substrate. Next, the control unit of the control device 91 determines the glass to be conveyed downward in the cold space 80 based on the displacement amount of the upper surface 62c (the maximum upper surface displacement amount L) and the thickness data of the glass substrate based on the shape distribution. The variation in the thickness of the strip 3 in the width direction is the smallest temperature distribution of the molten glass 2. Specifically, the control unit determines the temperature distribution such that the temperature of the first end portion 62d1 of the temperature distribution becomes lower as the maximum upper surface displacement amount L increases, and the central portion of the temperature distribution The higher the temperature, the higher the value.

Then, the control unit of the control device 91 controls the radiant heat of the heating element 48 in such a manner as to achieve the determined temperature distribution. By the above steps, the control device 91 controls the heating element 48 based on the shape data of the creep deformed molded body 62, thereby controlling the temperature of the molten glass 2. Degree distribution.

Next, the reason for the fact that the temperature of the first end portion 62d1 of the temperature distribution determined by the control unit is changed to be larger as the maximum upper surface displacement amount L of the molded body 62 which is subjected to the creep deformation is changed The value is low, and the temperature in the central portion of the temperature distribution is changed to a higher value. As described above, the larger the maximum upper surface displacement amount L is, the larger the thickness variation of the glass ribbon 3 in the width direction is, and the thickness of the central portion of the glass ribbon 3 in the width direction is larger than the thickness of both end portions in the width direction. In this case, when the radiant heat of each of the heating elements 48 is individually adjusted to lower the temperature of the first end portion 62d1 of the temperature distribution of the molten glass 2, the first end portion 62d1 side of the glass ribbon 3 is used for the above reason. The thickness becomes larger. In addition, when the radiant heat of each of the heat generating bodies 48 is individually adjusted to increase the temperature of the central portion of the temperature distribution of the molten glass 2, the thickness of the second end portion 62d2 side of the glass ribbon 3 is increased for the above reason. The thickness of the central portion in the width direction of the glass ribbon 3 becomes small. As a result, the difference between the thickness of the central portion in the width direction of the glass ribbon 3 and the thickness of both end portions in the width direction becomes small, and the thickness of the glass ribbon 3 becomes uniform in the width direction. That is, the variation in the thickness of the glass ribbon 3 in the width direction is reduced.

In addition, by controlling the temperature (viscosity) of the molten glass 2 overflowing from the upper surface 62c of the molded body 62 from the first end portion 62d1 to the second end portion 62d2, the glass ribbon 3 is controlled. The thickness deviation in the width direction is reduced. However, the central portion of the formed glass ribbon 3 in the width direction is thickened by the creep deformation of the molded body 62. In order to reduce the thickness of the central portion in the width direction of the glass ribbon 3, it is necessary to lower the viscosity of the molten glass 2 flowing in the central portion between the first end portion 62d1 and the second end portion 62d2 of the supply groove 62b. Therefore, the viscosity of the molten glass 2 flowing in the first end portion 62d1 on the upstream side is increased as compared with the central portion between the first end portion 62d1 and the second end portion 62d2, whereby the glass ribbon 3 is increased. The central portion in the width direction is thinned, and the side of the first end portion 62d1 of the glass ribbon 3 is slightly thinned. In addition, the viscosity of the molten glass 2 flowing in the central portion located on the upstream side is lowered as compared with the second end portion 62d2, whereby the first end portion 62d1 side of the glass ribbon 3 is thickened, and the glass ribbon 3 is thickened. The center portion in the width direction is slightly thicker. The thickness of the central portion in the width direction of the glass ribbon 3 is based on the first end portion 62d1 side. The temperature distribution changes from the central portion downstream of the first end portion 62d1 side. The temperature in the vicinity of the position of the supply groove 62b is increased, the temperature on the side of the first end portion 62d1 is lowered, and the distance between the first end portion 62d1 and the second end portion 62d2 is increased as compared with the initial temperature distribution before the creep deformation is generated. The temperature of the central portion increases the temperature of the second end portion 62d2 side, whereby the variation in the thickness of the glass ribbon 3 in the width direction after the creep deformation of the molded body 62 can be suppressed.

Therefore, the glass substrate manufacturing apparatus 1 can be bent by bending the central portion of the longitudinal direction of the molded body 62 by the creep deformation of the molded body 62, and the molded body can be formed by using the heating element 48. The temperature distribution of the molten glass 2 which is in contact with the upper surface 62c of 62 is controlled to reduce the variation in the thickness of the glass ribbon 3 in the width direction. As a result, the glass substrate manufacturing apparatus 1 can reduce the variation in the thickness of the glass substrate as the final product.

Further, in the production step of using a glass substrate having a high liquidus temperature and a glass substrate having a high strain point, the creep deformation of the molded body 62 is particularly likely to be a problem because the temperature of the molded body 62 is likely to become high. In addition, in recent years, the size of the glass substrate is increased, and the size of the molded body in the longitudinal direction is increased. Therefore, the deflection of the molded body 62 due to creep deformation tends to be more remarkable. In the glass substrate manufacturing apparatus 1 of the present embodiment, the radiant heat of the plurality of heat generating bodies 48 provided above the molded body 62 is adjusted to control the temperature distribution of the molten glass 2 that is in contact with the upper surface 62c of the molded body 62. The thickness deviation of the glass ribbon 3 in the width direction caused by the creep deformation of the molded body 62 can be effectively reduced.

(6) Variations

(6-1) Change A

In the embodiment, the acquisition unit of the control device 91 of the glass substrate manufacturing apparatus 1 obtains shape data relating to the current shape of the molded body 62 by temporally changing the shape of the molded body 62 by computer simulation. However, the acquisition unit may also acquire shape data related to the current shape of the formed body 62 by other methods.

For example, the acquisition unit may acquire the shape data based on the measured values of the shape of the molded body 62. In this case, it is necessary to collect in advance the assets related to the measured values of the shape of the formed body 62. Materials and materials related to the conditions of use of the molded body 62 were analyzed. The conditions of use of the molded body 62 are various parameters relating to the molded body 62 such as the operation 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. The acquisition unit predicts and acquires the shape data of the currently used molded body 62 based on the correlation between the data relating to the measured value of the shape of the formed body 62 and the data relating to the use conditions of the molded body 62.

Moreover, the acquisition unit can also acquire the shape data based on the measured value of the thickness of the glass ribbon 3 formed by the molded body 62. In this case, the acquisition unit acquires data relating to the measured value of the thickness of the glass ribbon 3 in the width direction from the start of the operation of the glass substrate manufacturing apparatus 1, based on the amount of change in the thickness according to the temporality and the operating conditions. The obtained analysis results predict and obtain the shape data of the molded body 62 currently in use.

(6-2) Change B

In the embodiment, the acquisition unit of the control device 91 of the glass substrate manufacturing apparatus 1 obtains shape data relating to the current shape of the molded body 62 by temporally changing the shape of the molded body 62 by computer simulation. However, the acquisition unit may also acquire shape data related to the current shape of the formed body 62 by other methods.

For example, the acquisition unit may also acquire the shape data according to the creep characteristic parameter. The creep characteristic parameter is a parameter for reproducing the relationship between the stress applied to the formed body 62, the temperature of the formed body 62, and the strain rate of the formed body 62 based on the creep deformation. Here, the stress applied to the formed body 62 is a force that compresses the formed body 62 along the longitudinal direction of the formed body 62. Further, it is assumed that the strain rate of the molded body 62 is fixed irrespective of time. Next, a method of determining the creep characteristic parameter will be described.

First, the strain rate of the molded body 62 under the condition that the stress applied to the molded body 62 is fixed depends on the change in the temperature of the molded body 62. Fig. 9 is an example of a graph showing the strain rate of the formed body 62 depending on the change in temperature. In Fig. 9, the magnitude of the stress applied to the formed body 62 was 2.0 MPa. The strain rate of the formed body 62 is utilized, for example, by The amount of change in the shape of the molded body 62 obtained by the four-point bending test of the molded body 62 was measured and calculated. In Fig. 9, the measured values of the strain velocity of the formed body 62 are indicated by black circles.

Next, the strain rate of the molded body 62 under the condition that the temperature of the molded body 62 is fixed depends on the change in the stress applied to the molded body 62. Fig. 10 is an example of a graph in which the strain rate of the formed body 62 depends on the change in stress. In Fig. 10, the temperature of the formed body 62 was 1,250 °C. The strain rate of the molded body 62 is calculated, for example, by measuring the amount of change in the shape of the molded body 62 by laser measurement. In Fig. 10, the measured values of the strain velocity of the formed body 62 are indicated by black circles.

Then, according to the following formula (1), the creep characteristic parameters A, B, and n which determine the strain rate of the reproducible molded body 62 depending on the change in temperature and the measured value depending on the change in stress are determined.

In the formula (1), R is 8.314 [J/mol‧K], ΔH is 4.500 × 10 ⁵ [J/mol], ε ' is the strain rate of the formed body 62 [/hour], and σ is applied to the forming The stress [Pa] of the body 62, T is the temperature [K] of the formed body 62. The creep characteristic parameters A[/hour], B[/Pa], and n are determined such that the strain rate obtained according to the formula (1) conforms to the measured value of the strain rate. In FIGS. 9 and 10, the strain rate of the molded body 62 calculated from the equation (1) based on the determined creep characteristic parameter is represented by a hollow square. Further, the creep characteristic parameters A, B, and n used in Figs. 9 and 10 are 8.648 × 10 ¹² [/hour], 4.491 × 10 ^-9 [/Pa], and 9.987 × 10 ^{-1 , respectively} .

Furthermore, the acquisition unit can also verify the creep characteristic parameters after determining the creep characteristic parameters. The verification of the creep characteristic parameter is performed, for example, by modeling the strain rate measurement system of the formed body 62 and using a computer simulation to confirm whether or not the strain rate based on the determined creep characteristic parameter has been obtained.

Moreover, the acquisition department is calculated by computer simulation using the determined creep characteristic parameters. The shape change of the shape of the molded body 62 is obtained by determining the time change of the shape of the molded body 62 at a specific temperature and stress rate of the molded body 62.

(6-3) Change C

In the embodiment, the control unit of the glass substrate manufacturing apparatus 1 uses the maximum upper surface displacement L shown in FIG. 8 as the shape data of the molded body 62, and determines the molten glass 2 based on the maximum upper surface displacement L. Temperature distribution. However, the control unit may determine the temperature distribution of the molten glass 2 using other parameters related to the shape data of the molded body 62.

For example, the control unit may determine the curvature of the upper surface 62c or the lower end 62a of the molded body 62 when viewed along a direction perpendicular to the surface of the glass ribbon 3 as a parameter relating to the shape data of the molded body 62. The temperature distribution of the molten glass 2. For example, the control unit may determine the temperature distribution in such a manner that the larger the curvature of the upper surface 62c or the lower end 62a of the molded body 62, the larger the amount of deflection of the molded body 62 due to creep deformation, so that the molten glass The temperature of the first end portion 62d1 of the temperature distribution of 2 becomes a lower value, and the temperature at the central portion of the temperature distribution becomes a higher value.

2‧‧‧Solid glass

3‧‧‧glass ribbon

42‧‧‧ furnace wall

44‧‧‧ top board

46‧‧‧ Upper temperature control space

48‧‧‧heating body

48a‧‧‧Cooling path

50c‧‧‧Transfer tube

60‧‧‧Upper forming space

62‧‧‧Formed body

62a‧‧‧Bottom

62b‧‧‧ supply slot

62c‧‧‧ upper surface

62d1‧‧‧1st end

62d2‧‧‧2nd end

64‧‧‧ upper spacer

70‧‧‧ Lower forming space

72‧‧‧Cooling roller

Claims (8)

A method for producing a glass substrate, comprising: a molding step of supplying molten glass to a supply tank formed on an upper surface of the molded body, and flowing the molten glass overflowing from the supply tank along both side surfaces of the molded body; And forming the glass ribbon by merging the molten glass flowing down the two sides on the lower end of the molded body; and carrying out the step of conveying the glass ribbon formed in the forming step downward while being cooled; a step of obtaining shape data relating to the shape of the formed body; and a controlling step of reducing the deviation of the plate pressure in the width direction of the glass ribbon from the shape data obtained in the obtaining step, The temperature distribution is controlled by a temperature adjustment mechanism provided above the molded body; and the temperature distribution is a distribution of the supply grooves in the longitudinal direction of the temperature of the molten glass in contact with the upper surface. The method for producing a glass substrate according to claim 1, wherein the obtaining step is to obtain the shape data based on creep deformation of the molded body. The method for producing a glass substrate according to claim 2, wherein the obtaining step is at least obtaining a displacement amount of the upper surface of the molded body in a vertical direction as the shape data, and the controlling step is based on the displacement in the longitudinal direction The distribution of the quantities, that is, the shape distribution, controls the above temperature distribution. The method of producing a glass substrate according to claim 3, wherein the controlling step controls the temperature distribution such that the amount of displacement of the shape distribution is larger as the temperature of the temperature distribution is higher. The method for producing a glass substrate according to any one of claims 1 to 4, wherein the obtaining step acquires the shape data by determining a temporal change of the shape by computer simulation. The method for producing a glass substrate according to claim 1, wherein the obtaining step acquires the shape data based on a thickness of the glass substrate which is conveyed downward and is cold-cooled in the transferring step. The method for producing a glass substrate according to any one of claims 1 to 6, wherein the temperature adjustment mechanism has a plurality of heat generating bodies disposed along the longitudinal direction. The method for producing a glass substrate according to claim 7, wherein the heat generating system has a space in which a fluid for cooling flows therein and has a rod-shaped ceramic heater extending in a direction orthogonal to the longitudinal direction.