TW201619074A - Manufacturing method of glass substrate, and manufacturing device of glass substrate - Google Patents

Abstract

The purpose of the present invention lies in providing a manufacturing method of the glass substrate capable of improving the quality of glass substrate manufactured by utilizing the Overflow Down Draw Process, and the manufacturing device of glass substrate. The manufacturing method of the glass substrate is to form the glass band 3 from the molten glass 2 by means of the Overflow Down Draw Process. The transportation step is to hold the glass band by utilizing the pairs of plural cooling rollers 82a~82g disposed along the perpendicular direction on one hand, and to make the cooling roller rotate to transport the glass band downwards. The measurement step is to determine the torque of the cooling roller in rotation during the period of transporting the glass band downwards. The adjustment step is to adjust the state of cooling roller based on the measured torque in the way of making the load of each cooling roller from the glass band transporting downwards reach uniformity.

Description

Method for producing glass substrate and device for manufacturing glass substrate

The present invention relates to a method for producing a glass substrate and a device for producing a glass substrate.

Glass substrates for flat panel displays (FPDs) such as liquid crystal displays and plasma displays require less strain, less warpage, and higher flatness. Such a glass substrate is produced by an overflow down-draw method as disclosed in Patent Document 1 (Japanese Patent Laid-Open Publication No. 2009-196879). The overflow down-draw method flows into the groove on the upper surface of the formed body and the molten glass overflowing from the groove flows downward along both sides of the formed body, and merges at the lower end of the formed body to form a glass ribbon. The glass ribbon is annealed while being conveyed to the lower side, and is cut into a glass substrate of a specific size. The glass substrate is packaged and shipped through an end surface processing step, a surface cleaning step, an inspection step, and the like.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-196879

The annealing step of the glass ribbon of the overflow down-draw method uses a plurality of rolls for transporting the glass ribbon to the lower side. The roller system is rotated while being in contact with both end portions in the width direction of the glass ribbon to pull the glass ribbon to the lower side. The contact load acts between the rolls and the glass ribbon.

Further, in the production of a glass substrate for a high definition display, a glass substrate having a small heat shrinkage rate and strain is required. In the manufacturing step of the glass substrate having such a property, there is a tendency that the temperature of the glass ribbon conveyed to the lower side in the annealing step is high. Therefore, there is a problem that the roller which is in contact with the glass ribbon of high temperature is easily deteriorated. Further, in order to manufacture a high-quality glass substrate, it is necessary to achieve a specific temperature distribution in the width direction of the glass ribbon with high precision in the annealing step. In particular, since a glass substrate for a high-definition display is required to have a low heat shrinkage rate, for example, a glass composition having a high strain point is applied. Further, in the production of a glass substrate for a high definition display, the heat shrinkage rate is required to be stable. Therefore, it is necessary to maintain the temperature of the glass substrate at a high level in the annealing step, and the space in which the annealing step is performed becomes an environment in which the roller is easily deteriorated. When the roll is deteriorated, the contact load between the rolls and the glass ribbon becomes uneven, and there is a cause of internal strain, vibration, and deformation of the glass ribbon.

An object of the present invention is to provide a method for producing a glass substrate which can improve the quality of a glass substrate produced by an overflow down-draw method, and a glass substrate manufacturing apparatus.

The method for producing a glass substrate of the present invention is a method for producing a glass substrate by forming a glass ribbon from molten glass by an overflow down-draw method. The method for producing a glass substrate includes a transport step, a measurement step, and an adjustment step. In the transport step, the glass ribbon is held by a plurality of roller pairs arranged in the vertical direction, and the roller is rotated to transfer the glass ribbon to the lower side. The measuring step is a period in which the glass ribbon is conveyed to the lower side, and the torque of the rotating roller is measured. The adjustment step is based on the measured torque, and the state of the roller is adjusted such that the load on the glass ribbon conveyed by each roller from the downward direction becomes uniform.

The method for producing the glass substrate is measured as a torque of a roller that rotates the glass ribbon to the lower side. Then, based on the measurement data of the torque of each roller, it was judged whether the contact load between each roller and the glass ribbon was uniform. Then, the state of the roller is adjusted in such a manner that the contact load is uniform. Thereby, the internal strain, vibration and deformation of the glass ribbon are suppressed. Therefore, the method of manufacturing the glass substrate can improve the quality of the glass substrate produced by the overflow down-draw method.

Further, in the method for producing a glass substrate of the present invention, the adjustment step is preferably such that when the difference between the torques of the two rolls adjacent to each other in the conveying direction of the glass ribbon is a specific value or more, the angular velocity of the two rolls is used. The state of the roller is adjusted in such a way that the difference becomes smaller.

In the method of manufacturing the glass substrate, when the difference between the torques of the two rolls adjacent to each other in the conveyance direction of the glass ribbon is equal to or greater than a specific reference value, the contact load between the rolls and the glass ribbon is determined to be non-uniform. In this case, the roller is controlled such that the difference between the angular velocities of the adjacent two rolls becomes small.

Further, in the method of manufacturing a glass substrate of the present invention, the adjusting step preferably controls the number of revolutions of the motor for rotating the roller to adjust the state of the roller.

In the method of manufacturing the glass substrate, when the difference between the torques of the two rolls adjacent to each other in the conveyance direction of the glass ribbon is equal to or greater than a specific reference value, the contact load between the rolls and the glass ribbon is determined to be non-uniform. In this case, the number of revolutions of the motor that drives the roller is controlled such that the difference between the angular velocities of the two adjacent rollers becomes smaller.

Further, in the method for producing a glass substrate of the present invention, the adjustment step is preferably a torque variation when the amount of torque fluctuation which is the difference between the maximum value and the minimum value of the torque is greater than or equal to a specific value during one rotation of the roller. The amount of the roller is adjusted in such a way that the amount becomes smaller.

The method for producing the glass substrate is to measure the change in the contact load between the roller and the glass ribbon based on the change in torque during one rotation of the roller. The excessive contact load is a cause of cracking or strain of the glass ribbon, and causes a change in the contact load between the roller adjacent to the glass ribbon in the conveying direction and the glass ribbon. Therefore, by adjusting the state of the roller so that the torque fluctuation amount becomes small, it is suppressed that an excessive contact load acts between the roller and the glass ribbon. Thereby, the internal strain, vibration and deformation of the glass ribbon are suppressed.

Further, in the method for producing a glass substrate of the present invention, the adjustment step preferably controls the contact load between the roll and the glass ribbon to adjust the state of the roll.

The method of manufacturing the glass substrate is such that when the contact load between the roller and the glass ribbon is excessive, for example, by adjusting the pressure of the cylinder for position adjustment of the roller, the excess is suppressed. The contact load acts between the roller and the glass ribbon.

Further, in the method for producing a glass substrate of the present invention, it is preferable that the adjustment step is to adjust the state of the roller by replacing the roller used in the transfer step with the backup roller.

The method for producing the glass substrate is such that when the roller is deteriorated due to long-term use, the contact load between each roller and the glass ribbon is made uniform by replacing the deteriorated roller with a new backup roller, and the excess is suppressed. The contact load acts between the roller and the glass ribbon.

The apparatus for producing a glass substrate of the present invention is a device for producing a glass substrate by forming a glass ribbon from molten glass by an overflow down-draw method. The glass substrate manufacturing apparatus includes a conveying unit, a measuring unit, and an adjusting unit. The conveyance unit has a plurality of roller pairs arranged along the vertical direction, and the glass ribbon is held by the pair of rollers, and the roller of the roller is rotated to convey the glass ribbon to the lower side. The measurement unit measures the torque of the roller during rotation while the glass ribbon is being conveyed to the lower side. The adjustment unit adjusts the state of the roller so that the load on the glass ribbon that is conveyed from the downward direction to the lower side is uniform based on the measured torque.

The method for producing a glass substrate of the present invention and the apparatus for producing a glass substrate can improve the quality of the glass substrate produced by the overflow down-draw method.

1‧‧‧Glass substrate manufacturing equipment

2‧‧‧Solid glass

3‧‧‧glass ribbon

10‧‧‧melting tank

20‧‧‧clarification tube

30‧‧‧Agitator

40‧‧‧Forming device

50a, 50b, 50c‧‧‧ transfer tube

60‧‧‧Upper forming space

62‧‧‧Formed body

62a‧‧‧ Lower end of the formed body

62b‧‧‧ slots

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‧‧‧ Annealing space

82a~82g‧‧‧Cooling roller (roller)

84a~84g‧‧‧heater

86‧‧‧Insulation members

91‧‧‧Control device

98‧‧‧cutting device

172‧‧‧Cooling roller drive motor

182‧‧‧Rolling roll drive motor

198‧‧‧cutting device drive motor

Fig. 1 is a flow chart showing a method of manufacturing a glass substrate according to the first embodiment.

Fig. 2 is a schematic view showing a manufacturing apparatus of a glass substrate according to the first embodiment.

Fig. 3 is a front elevational view showing the molding apparatus of the first embodiment.

Fig. 4 is a side view of the molding apparatus of the first embodiment.

Fig. 5 is a block diagram of a control device according to the first embodiment.

Fig. 6 is a graph showing changes in torque of a rolling roll due to long-term use in the first embodiment.

Fig. 7 is a graph showing changes in torque of a rolling roll due to long-term use in the first embodiment.

Fig. 8 is a graph showing an example of a change in torque during a period in which the rolling rolls are rotated one rotation in the second embodiment.

- First embodiment -

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

The first embodiment of the method for producing a glass substrate of the present invention and the apparatus for producing a glass substrate will be described with reference to the drawings. Fig. 1 is a flow chart showing an example of a method for 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 the melting step S1, the clarification step S2, the stirring step S3, the molding step S4, the cooling step S5, and the cutting step S6.

The melting step S1 heats the glass raw material 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. SnO _{2 was} used as a fining agent in view of reducing the environmental load.

In the clarification step S2, the molten glass obtained in the melting step S1 flows inside the clarification pipe, and the gas contained in the molten glass is removed, whereby the molten glass is clarified. First, in the clarification step S2, the temperature of the molten glass is raised. The clarifying agent added to the molten glass causes a reduction reaction due to the temperature rise, and releases oxygen. The bubbles containing gas components such as CO ₂ , N ₂ , and SO ₂ contained in the molten glass absorb oxygen generated by the reduction reaction of the clarifying agent. The bubble that has grown by absorbing oxygen floats up to the liquid surface of the molten glass, and then ruptures and disappears. The gas contained in the disappearing bubble is released into the gas phase space inside the clarification pipe and discharged to the outside atmosphere. Then, in the clarification step S2, the temperature of the molten glass is lowered. Thereby, the reduced clarifying agent causes an oxidation reaction and absorbs a gas component such as oxygen remaining in the molten glass.

In the stirring step S3, the molten glass from which the gas is removed in the clarification step S2 is stirred to homogenize the components of the molten glass. Thereby, the composition unevenness of the molten glass which is a stripe of a glass substrate etc. is reduced.

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

In the cooling step S5, the formed glass ribbon in the forming step S4 is cooled. The cooling step S5 prevents the glass ribbon from being slowly cooled while adjusting the temperature of the glass ribbon in such a manner as to cause strain and warpage in the glass ribbon.

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, the end surface of the glass substrate is ground and polished, and the glass substrate is washed. Thereafter, the glass substrate is inspected for defects such as scratches, and the glass substrate that has passed the inspection is packaged 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 has 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 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. In the cooling step S5, the glass ribbon 3 is cooled while being conveyed to the lower side. In the cutting step S6, the glass ribbon 3 to be cooled 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 manufactured by the glass substrate manufacturing apparatus 1 is especially 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, an alkali-free glass, a trace amount of alkali-containing glass, a glass for low temperature polycrystalline silicon (LTPS), or a glass for an 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 which is a raw material for 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 suitable for the 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 trace amount of alkali-containing glass containing an alkali metal in a small amount can be used. The trace alkali glass 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 content of R' ₂ O may also be less than 0.1% by mass in total.

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. (it is preferably 0.01% by mass to 0.08% by mass). Further, 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 from the viewpoint of reducing environmental load.

The glass raw material prepared in the above-described composition is supplied to the melting tank 10 using a raw material loader (not shown). The raw material loader can use the screw feeder to input the glass raw material, or use the bucket to input the glass raw material. 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, a molten glass 2 having a high temperature of, for example, 1500 ° C to 1600 ° C is obtained. In the melting tank 10, a current can flow between at least one pair of electrodes formed by molybdenum, platinum, tin oxide, or the like. The molten glass 2 between the electrodes is electrically heated, and in addition to the electric heating, the glass raw material can be additionally heated by the flame of the burner.

The molten glass 2 obtained in the melting tank 10 flows from the melting tank 10 through the transfer pipe 50a into the clarification pipe 20. 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 mechanism is provided similarly to 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 is raised to 1500 ° C to 1700 ° C.

The clarified molten glass 2 in the clarification pipe 20 flows from the clarification pipe 20 through the transfer pipe 50b into 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 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 while passing through the transfer pipe 50c to have a viscosity suitable for forming the molten glass 2. For example, the molten glass 2 is cooled to around 1200 °C.

The forming apparatus 40 is formed into a glass ribbon 3 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 elevational view of the forming device 40. Figure 3 shows the forming device 40 as viewed along a direction perpendicular to the surface of the glass ribbon 3 formed in the forming device 40. 4 is a side view of the forming device 40. 4 shows the forming device 40 as viewed in a direction parallel to the surface of the glass ribbon 3 formed in the forming device 40.

The molding apparatus 40 has a space surrounded by a furnace wall (not shown) including a refractory such as refractory brick. This space is formed from the molten glass 2 into a glass ribbon 3, and the glass ribbon 3 is cooled. between. This space includes three spaces of the upper forming space 60, the lower forming space 70, and the annealing space 80.

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 annealing 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 the glass ribbon 3 is quenched to a space in the vicinity of the annealing point of the glass. The annealing space 80 is a space below the lower forming space 70, and the glass ribbon 3 is slowly cooled.

The molding apparatus 40 mainly includes a molded body 62, an upper partition member 64, a cooling roll 72, a temperature adjusting unit 74, a lower partition member 76, calender rolls 82a to 82g, heaters 84a to 84g, a heat insulating member 86, a cutting device 98, And a 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 used to form the glass ribbon 3 by overflowing the molten glass 2 . 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.

A groove 62b is formed in the upper end surface of the molded body 62 along the longitudinal direction of the molded body 62. A transfer pipe 50c that communicates with the groove 62b is attached to an end portion of the molded body 62 in the longitudinal direction. The groove 62b is formed to gradually become shallow as it comes from one end portion communicating with the transfer pipe 50c toward the other end portion.

The molten glass 2 conveyed from the stirring device 30 to the molding device 40 flows into the groove 62b of the molded body 62 via the transfer pipe 50c. The molten glass 2 overflowing from the groove 62b of the molded body 62 flows downward along both side faces 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 merging falls in the vertical direction by gravity, and is formed into a plate shape. Thereby, the glass ribbon 3 is continuously formed in the vicinity of the lower end 62a of the molded body 62. Has After the formed glass ribbon 3 flows downward to the upper molding space 60, it is cooled while being cooled in the lower molding space 70 and the annealing space 80, and is conveyed to the lower side. The temperature of the glass ribbon 3 immediately after forming in the upper forming space 60 is 1100 ° C or more, and the viscosity is 25000 poise to 350,000 poise. For example, in the case of manufacturing a glass substrate for a high-definition display, the glass ribbon 3 formed by the molded body 62 has a strain point of 655 ° C to 750 ° C, preferably 680 ° C to 730 ° C, and is formed on the molded body. The viscosity of the molten glass 2 fused near the lower end 62a of 62 is 25000 poise to 100000 poise, preferably 32,000 poise to 80000 poise.

(2-2) 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 separates the upper forming space 60 from the lower forming space 70, and prevents heat from moving from the upper forming space 60 toward the lower forming space 70.

(2-3) 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 below the upper partition member 64. As shown in FIG. 3, the cooling rolls 72 are disposed on both side portions in 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 attached to both sides in the width direction thereof, and is held by the cooling roller 72. The cooling roller 72 cools the glass ribbon 3 conveyed from the upper forming space 60.

In the lower forming space 70, both side portions in the width direction of the glass ribbon 3 are sandwiched by the pair of cooling rolls 72, respectively. By pressing the cooling roller 72 toward the surfaces of both side portions of the glass ribbon 3, the contact area between the cooling roller 72 and the glass ribbon 3 is increased, and the cooling of the glass ribbon 3 by the cooling roller 72 is effectively performed. The cooling roller 72 imparts a force to the glass ribbon 3 against the force of pulling the glass ribbon 3 downward by the following rolling rolls 82a to 82g. 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 calender roll 82a disposed at the uppermost position.

The cooling roller 72 has an air cooling tube inside. The chill roll 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 of the glass ribbon 3 in the width direction are cooled. The viscosity of both sides in the width direction of the glass ribbon 3 which is cooled in contact with the cooling roll 72 is, for example, 10 ^9.0 poise or more.

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

(2-4) 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 annealing point. 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 central 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 temperatures 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 indicates 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 arranged in a vertical direction in 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.

(2-5) lower spacer member

The lower spacer member 76 is disposed below one of the temperature adjusting unit 74 to the plate shape. Insulation member. As shown in FIG. 4, the lower partition members 76 are disposed on both sides in the thickness direction of the glass ribbon 3. The lower partition member 76 separates the lower forming space 70 from the annealing space 80 in the vertical direction, thereby suppressing the movement of heat from the lower forming space 70 toward the annealing space 80.

(2-6) calender roll

The calender rolls 82a to 82g are cantilever rolls provided in the annealing space 80. In the annealing space 80, the rolling rolls 82a, the rolling rolls 82b, ..., the rolling rolls 82f, and the rolling rolls 82g are arranged at intervals from above. The rolling rolls 82a are disposed at the uppermost position, and the rolling rolls 82g are disposed at the lowest position.

As shown in Fig. 3, the rolling rolls 82a to 82g are disposed on both side portions in the width direction of the glass ribbon 3, respectively. As shown in Fig. 4, the rolling rolls 82a to 82g are disposed on both sides in the thickness direction of the glass ribbon 3, respectively. In other words, both side portions in the width direction of the glass ribbon 3 are directed downward from the upper side, and are sandwiched between the pair of rolling rolls 82a and 2, the pair of rolling rolls 82b, ..., the pair of rolling rolls 82f, and the pair of rolling rolls 82g.

The rolling rolls 82a to 82g are rotated while being sandwiched by both end portions in the width direction of the glass ribbon 3 that has passed through the lower molding space 70, and the glass ribbon 3 is pulled down to the lower side in the vertical direction. That is, the rolling rolls 82a to 82g are used to convey the glass ribbon 3 to the lower roller.

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

(2-7) heater

The heaters 84a to 84g are provided in the annealing space 80. As shown in FIG. 4, in the annealing space 80, the heater 84a, the heater 84b, ..., the heater 84f, and the heater 84g are arranged at intervals from the upper side toward the lower side. The heaters 84a to 84g are disposed on both sides in the thickness direction of the glass ribbon 3, respectively. The rolling rolls 82a to 82g are disposed between the heaters 84a to 84g and the glass ribbon 3, respectively.

The heaters 84a-84g are directed toward the surface of the glass ribbon 3, and the radiant heat is added to the glass ribbon 3 heat. The temperature of the glass ribbon 3 conveyed to the lower side can be adjusted in the annealing space 80 by using the heaters 84a to 84g. Thereby, the heaters 84a to 84g can form a specific temperature distribution on 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 heater subunits (not shown) along the width direction of the glass ribbon 3, and the outputs of the heater subunits may be independently controlled by the control device 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 environment of the annealing 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-84g can also be controlled based on the temperature of the environment in which the annealing space 80 is measured by the thermocouple.

(2-8) Insulation member

The heat insulating member 86 is disposed in the annealing space 80. The heat insulating member 86 is disposed at a height position between the two rolling rolls 82a to 82g adjacent to each other in the conveying 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 in the thickness direction of the glass ribbon 3 to form a pair of heat insulating sheets. The heat insulating member 86 separates the annealing space 80 in the vertical direction, and suppresses thermal movement in the vertical direction in the annealing space 80.

The heat insulating member 86 is provided so as not to be in contact with the glass ribbon 3 conveyed to the lower side. Further, the heat insulating member 86 is provided so as to be adjustable to the distance from the surface of the glass ribbon 3. Thereby, the heat insulating member 86 suppresses heat transfer 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 disposed in a space below the annealing space 80. The cutting device 98 cuts the glass ribbon 3 passing through the annealing space 80 in the width direction of the glass ribbon 3 for each specific size. The glass ribbon 3 passing through the annealing space 80 is cooled to a flat temperature near room temperature. Glass belt 3.

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, a glass substrate having a size close to the final product can be mass-produced.

(2-10) Control device

The control device 91 mainly includes a computer such as a CPU (central processing unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a hard disk. FIG. 5 is a block diagram of the control device 91. As shown in FIG. 5, the control device 91 is connected to the cooling roll drive motor 172, the temperature adjustment unit 74, the rolling roll drive motor 182, the heaters 84a to 84g, 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 calender roll drive motor 182 is a motor for independently controlling the position and rotation speed of each of the calender rolls 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 acquires the state of each component and stores a program for 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 in the width direction of the holding glass ribbon 3 and the cooling roller 72 and the glass ribbon 3. The control device 91 can control the calender roll drive motor 182 to obtain the torque of each of the calender rolls 82a to 82g in rotation, and adjust the angular velocities of the respective calender rolls 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 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 conveyed from the stirring device 30 to the forming device 40 via the transfer pipe 50c is supplied to the groove 62b formed on the upper surface of the molded body 62. The molten glass 2 overflowing from the groove 62b of the molded body 62 follows the both sides of the formed body 62 downward. The motion is merged and merged near the lower end 62a of the formed body 62. In the vicinity of the lower end 62a of the formed body 62, the molten glass 2 which has merged from the continuous flow is continuously formed into the glass ribbon 3. The formed glass ribbon 3 is conveyed 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 roll 72 to be quenched. Further, the temperature of the glass ribbon 3 is adjusted by the temperature adjusting unit 74 until the temperature of the central portion in the width direction of the glass ribbon 3 is lowered to the annealing point. The glass ribbon 3 cooled by the cooling roll 72 while being conveyed to the lower side is conveyed to the annealing space 80.

In the annealing space 80, the glass ribbon 3 is slowly cooled while being pulled down by the rolling rolls 82a to 82g. 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 annealing space 80, the temperature of the glass ribbon 3 is slowly lowered from the vicinity of the annealing point to a temperature lower than the temperature lower than the strain point by 200 °C.

The glass ribbon 3 passing through the annealing space 80 is further cooled to near room temperature, and cut into a specific size by a cutting device 98 to obtain a glass substrate. Thereafter, polishing and washing of the end faces of the glass substrate are performed. Thereafter, a specific glass substrate that has passed the inspection is packaged and shipped as a product.

(4) Action of the control device

The control device 91 of the glass substrate manufacturing apparatus 1 stores and executes at least three programs including a transport unit, a measurement unit, and an adjustment unit. In the conveyance unit, the glass ribbon 3 is held by the rolling rolls 82a to 82g, and the rolling rolls 82a to 82g are rotated, and the glass ribbon 3 is conveyed to the lower side in the annealing space 80. The measurement unit measures the torque of the rolling rolls 82a to 82g that rotate while contacting the glass ribbon 3 in the annealing space 80 while the glass ribbon 3 is being conveyed to the lower side. The adjustment unit determines whether or not the difference in torque between the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is a specific value or more. For example, the adjustment unit compares the torque of the rolling roll 82a with the torque of the rolling roll 82b, and determines whether or not the difference between the two torques is equal to or greater than a specific value. Specifically, one of the four calender rolls 82a and four rolls are rolled. One of the rollers 82b is compared. The rolling rolls 82a and the rolling rolls 82b which are the comparison targets of the torques have the same position in the horizontal plane, and only the height positions are different.

When the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is a specific value or more, the difference between the angular velocities of the two rolling rolls 82a to 82g becomes small. In this manner, the state of the rolling rolls 82a to 82g is adjusted. Specifically, the adjustment unit controls the number of rotations of the drive motor connected to the calender rolls 82a to 82g, and adjusts the angular velocities of the calender rolls 82a to 82g. Each of the calender rolls 82a to 82g is connected to a different drive motor, so that the angular velocities of the respective calender rolls 82a to 82g can be independently controlled. In the adjustment unit, the angular velocities of the rolling rolls 82a to 82g are adjusted such that the difference between the angular velocities of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is small. Thereby, the adjustment unit can make the contact load between the glass ribbon 3 conveyed to the lower side and each of the rolling rolls 82a to 82g uniform based on the measurement data of the torque of the rolling rolls 82a to 82g.

(5) Features

In the manufacturing step of the glass substrate in the overflow down-draw method, the glass ribbon formed from the molten glass is annealed while being conveyed to the lower side by the rolling rolls. The calender rolls that are in contact with the high temperature glass ribbon deteriorate due to long-term use. In particular, the manufacturing process of the glass substrate for a high-definition display requiring a glass substrate having a small heat shrinkage rate and strain is higher than that of a normal glass substrate, and the temperature of the glass ribbon which is conveyed to the lower side while being annealed is higher. Thus, the calender rolls are easily deteriorated. Further, in order to manufacture a high-quality glass substrate, it is necessary to control the temperature distribution in the width direction of the glass ribbon with high precision in the annealing step of the glass ribbon. When the calender roll is deteriorated, the contact load between each of the calender rolls and the glass ribbon becomes uneven, which causes internal strain, vibration, and deformation of the glass ribbon, and the quality of the glass substrate is lowered.

The glass substrate manufacturing apparatus 1 of the present embodiment includes rolling rolls 82a to 82g for conveying the glass ribbon 3 formed from the molten glass 2 by the overflow down-draw method while being cooled. The calender rolls 82a to 82g are held by the ends of the width direction of the glass ribbon 3 The part is rotated and the glass ribbon 3 is pulled down. At this time, the contact load acts between the respective rolling rolls 82a to 82g and the glass ribbon 3.

In the control device 91 of the glass substrate manufacturing apparatus 1, the contact load between each of the rolling rolls 82a to 82g and the glass ribbon 3 is made uniform by measuring and adjusting the torque of each of the rolling rolls 82a to 82g. Specifically, when the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is a specific value or more, the angular velocity of the two rolling rolls 82a to 82g is adjusted. Reduce the difference in torque. The control device 91 adjusts the angular velocity of each of the calender rolls 82a to 82g so that the torque of each of the calender rolls 82a to 82g is uniform, and the contact load between each of the calender rolls 82a to 82g and the glass ribbon 3 is uniform. Thereby, the internal strain, vibration, and deformation of the glass ribbon 3 are suppressed, and the quality of the glass substrate is improved.

Then, in order to show that the quality of the glass substrate is improved by the glass substrate manufacturing apparatus 1, the difference in torque between the two rolling rolls 82a and 82b adjacent to the conveying direction of the glass ribbon 3 is a specific value or more. In the case, the problem caused by the angular velocity of the rolling rolls 82a and 82b is not adjusted.

Fig. 6 is a graph showing changes in torque of the calender rolls 82a, 82b caused by long-term use. In Fig. 6, the horizontal axis represents time and the vertical axis represents the magnitude of torque. In Fig. 6, the solid line indicates the time change of the torque of the calender roll 82a, and the broken line indicates the time change of the torque of the calender roll 82b located below the calender roll 82a. Fig. 6 is a view showing a mode in which the wear speed of the calender roll 82a is greater than the wear speed of the calender roll 82b. In this case, the outer diameter of the calender roll 82a becomes smaller in a shorter time due to abrasion than the outer diameter of the calender roll 82b. Therefore, due to long-term use, the contact overload between the calender roll 82a and the glass ribbon 3 becomes smaller than the contact overload between the calender roll 82b and the glass ribbon 3, and as a result, the time from the start of use of the calender rolls 82a, 82b As a result, the torque of the calender roll 82a becomes smaller than the torque of the calender roll 82b. Thereby, the speed at which the rolling roll 82a conveys the glass ribbon 3 downward is made smaller than the speed at which the rolling roll 82b transports the glass ribbon 3 downward. Between the calender roll 82a and the calender roll 82b, the force of pulling the glass ribbon 3 along the conveyance direction acts on the glass ribbon 3. If the force acts excessively, it becomes a cause of cracking or strain of the glass ribbon 3.

Fig. 7 is a graph similar to Fig. 6, and shows a mode in which the wear speed of the calender roll 82b is greater than the wear speed of the calender roll 82a. In this case, the torque of the calender roll 82b becomes smaller than the torque of the calender roll 82a due to long-term use. Thereby, the speed at which the rolling roll 82a conveys the glass ribbon 3 downward is greater than the speed at which the rolling roll 82b transports the glass ribbon 3 downward, and therefore, the rolling roll 82a and the rolling roll 82b are compressed in the conveying direction. The force of the glass ribbon 3 acts on the glass ribbon 3. When the force acts excessively, the surface of the glass ribbon 3 is bent, which causes the glass ribbon 3 to be conveyed to vibrate. The vibration of the glass ribbon 3 causes the glass ribbon 3 to crack or strain.

As a result, in any of the modes of FIGS. 6 and 7, the difference in torque between the two rolling rolls 82a and 82b adjacent to the conveying direction of the glass ribbon 3 causes the quality of the glass substrate to deteriorate. Therefore, the glass substrate manufacturing apparatus 1 can reduce the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3, and between the rolling rolls 82a to 82g and the glass ribbon 3 The contact load is uniform, and the quality of the glass substrate manufactured by the overflow down-draw method is improved.

- Second embodiment -

The second embodiment of the method for producing a glass substrate of the present invention and the apparatus for manufacturing a glass substrate will be described with reference to the drawings. The glass substrate manufacturing apparatus of the present embodiment is the same as the glass substrate manufacturing apparatus 1 of the first embodiment except for the operation of the adjustment unit of the control device 91. Therefore, the description relating to the configuration of the glass substrate manufacturing apparatus will be omitted, and the operation of the adjustment unit of the control device 91 will be mainly described.

In the present embodiment, when the adjustment portion of the control unit 91 rotates the rolling rolls 82a to 82g for one rotation, the difference between the maximum value and the minimum value of the torque, that is, the torque variation amount is equal to or greater than a specific value, the torque variation amount is reduced. The state of the rolling rolls 82a to 82g is adjusted in a manner.

The change in torque is mainly caused by the eccentricity of the rotating shaft of the rolling rolls 82a to 82g. When the rotation axes of the rolling rolls 82a to 82g are eccentric, the rolling rolls 82a to 82g vibrate at the time of rotation. As a result, there is a possibility that the torque changes during the one rotation of the rolling rolls 82a to 82g, and when the torque becomes maximum, an excessive contact load acts between the rolling rolls 82a to 82g and the glass ribbon 3. Excessive contact load becomes a cause of cracking or strain of the glass ribbon 3. Further, when the rolling rolls 82a to 82g increase the force of the glass ribbon 3 toward the lower side due to the excessive contact load, the burden of the upper rolling rolls 82a to 82g increases. On the other hand, if the contact force of the rolling rolls 82a to 82g to convey the glass ribbon 3 downward is reduced by too little contact load, the burden of the lower rolling rolls 82a to 82g is increased. As a result, the periodic fluctuation of the torque of the rolling rolls 82a to 82g becomes a periodic fluctuation of the contact load, and the contact load between the adjacent rolling rolls 82a to 82g and the glass ribbon 3 in the conveying direction of the glass ribbon 3 changes. The quality of the glass substrate is degraded.

In the present embodiment, the change in the torque during the period in which the rolling rolls 82a to 82g are rotated by one rotation is measured. Then, by adjusting the state of the rolling rolls 82a to 82g so that the amount of torque fluctuation of the rolling rolls 82a to 82g is small, the fluctuation of the contact load between the rolling rolls 82a to 82g and the glass ribbon 3 is suppressed, thereby preventing excessive contact. The load acts on the glass ribbon 3. Specifically, by reducing the contact load between one of the end portions of the glass ribbon 3 in the width direction and the rolling rolls 82a to 82g and the glass ribbon 3, the variation in contact load is suppressed, thereby preventing excessive contact load. Acts on the glass ribbon 3. In the present embodiment, the control device 91 can control the rolling roller drive motor 182 to adjust the contact load between one of the end portions of the glass ribbon 3 in the width direction and the rolling rolls 82a to 82g and the glass ribbon 3. The contact load is adjusted, for example, by changing the pressure of the cylinder for adjusting the position of the rolling rolls 82a to 82g. Furthermore, the contact load can also be adjusted using an actuator other than the cylinder.

Fig. 8 is a graph showing an example of a change in torque during a period in which the rolling roll 82a is rotated. In FIG. 8, the period from the time t1 to the time t2 is the time required for the rolling roll 82a to rotate one revolution. The amount of torque variation during the rotation of the solid line rolling roll 82a is one The graph when the value is above. The dotted line is a pattern in which the contact load between the one end portion in the width direction of the glass ribbon 3 and the rolling roll 82a and the glass ribbon 3 is reduced from the state of the solid line. The chain line is a graph showing an ideal state in which the amount of torque fluctuation is zero. In Fig. 8, in the solid line pattern, in the vicinity of the time t3 at which the torque becomes maximum, excessive contact acts between the load rolling roll 82a and the glass ribbon 3. On the other hand, the graph of the broken line is smaller than the pattern of the solid line, and the maximum value of the torque at the time t3 is small, so that the contact load is also small, thereby preventing excessive contact load from acting on the glass ribbon 3.

Therefore, in the glass substrate manufacturing apparatus of the present embodiment, the difference between the maximum value and the minimum value of the torque during the period in which the rolling rolls 82a to 82g are rotated by one rotation can be reduced, and the excessive contact load can be prevented from acting on the glass ribbon 3. Thereby the quality of the glass substrate is improved.

-Changes -

(1) Change A

In the first embodiment, the state of the rolling rolls 82a to 82g is adjusted by reducing the difference in torque between the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3, and the second embodiment is The difference between the maximum value and the minimum value of the torque during the one-rotation of the rolling rolls 82a to 82g is reduced, and the state of the rolling rolls 82a to 82g is adjusted. However, in the first embodiment and the second embodiment, the state of the rolling rolls 82a to 82g may be adjusted by another method.

For example, when it is determined that the adjustment unit has to adjust the state of the rolling rolls 82a to 82g, the calender rolls 82a to 82g which are currently used may be replaced with the new new calender rolls 82a to 82g, and the calender rolls 82a may be adjusted. State of 82g. Therefore, when the calender rolls 82a to 82g are deteriorated due to long-term use, the quality of the glass substrate can be improved by replacing the deteriorated calender rolls 82a to 82g with the new calender rolls 82a to 82g.

(2) Change B

In the first embodiment, the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is reduced, and the state of the rolling rolls 82a to 82g is adjusted. Improve the quality of the glass substrate. However, the state of the rolling rolls 82a to 82g can be adjusted by reducing the difference in torque between the two rolling rolls 82a to 82g adjacent in the width direction of the glass ribbon 3. For example, when the difference between the torque of the rolling roll 82a which is in contact with one of the end portions in the width direction of the glass ribbon 3 and the torque of the rolling roll 82a which is in contact with the other end portion is a specific value or more, the torque can also be used. The state of the rolling roll 82a is adjusted in such a manner that the difference is reduced.

In this case, the difference in torque between one of the same height positions and the rolling roll 82a causes a speed difference between both end portions in the width direction of the glass ribbon 3 conveyed downward, and therefore, the glass ribbon 3 is twisted. It becomes the cause of the crack or strain of the glass ribbon 3. Therefore, the quality of the glass substrate can be improved by lowering the difference in torque between the rolling rolls 82a to 82g at the same height position.

(3) Change C

In the first embodiment, the state of the rolling rolls 82a to 82g is adjusted by reducing the difference in torque between the two rolling rolls 82a to 82g adjacent to the conveying direction of the glass ribbon 3, and the second embodiment is reduced by the second embodiment. The state of the rolling rolls 82a to 82g is adjusted by the difference between the maximum value and the minimum value of the torque during the period in which the small rolling rolls 82a to 82g rotate one revolution. However, it is also possible to reduce the difference in torque between the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3, and to reduce the maximum value of the torque during the one rotation of the rolling rolls 82a to 82g. The difference between the minimum value and the minimum value, that is, the amount of torque fluctuation, adjusts the state of the rolling rolls 82a to 82g.

(4) Change D

In the first embodiment, when the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction of the glass ribbon 3 is a specific value or more, the two rolling rolls 82a are adjusted. 82g angular velocity, reducing the difference in torque. Thereby, the control device 91 makes the torque of each of the rolling rolls 82a to 82g uniform, so that the contact load between each of the rolling rolls 82a to 82g and the glass ribbon 3 is uniform.

However, the control device 91 may adjust the angular velocities of the calender rolls 82a to 82g based on other conditions to make the contact load between the calender rolls 82a to 82g and the glass ribbon 3 uniform.

As an example, when the difference between the torques of the two rolling rolls 82a to 82g adjacent to each other in the conveying direction is equal to or greater than a specific reference value, the angular velocity of the two rolling rolls 82a to 82g may be adjusted. The difference between the small torques is smaller, and a smaller reference value is used for the two rolling rolls 82a to 82g disposed above. In the annealing space 80, the calender rolls 82a to 82g disposed above the upper portion are likely to deteriorate due to high temperature. Therefore, the torque of each of the calender rolls 82a to 82g can be effectively made uniform by adjusting the angular velocities of the calender rolls 82a to 82g disposed at the upper side more frequently.

As another example, the control device 91 may calculate all the torque differences between the two rolling rolls 82a to 82g adjacent to each other in the conveying direction, and adjust the deviation when the dispersion or standard deviation of all the torque differences exceeds a certain value. The angular velocity of the rolled rolls 82a to 82g.

(5) Change E

In the second embodiment, the control device 91 adjusts the state of the rolling rolls 82a to 82g so that the amount of torque fluctuation during the period in which the rolling rolls 82a to 82g rotate for one week, thereby suppressing the rolling rolls 82a to 82g and the glass ribbon. The change in contact load between 3.

However, the control device 91 can adjust the state of the rolling rolls 82a to 82g based on other conditions, and suppress the fluctuation of the contact load between the rolling rolls 82a to 82g and the glass ribbon 3.

As an example, when the amount of torque fluctuation of the rolling rolls 82a to 82g is equal to or greater than a specific reference value, the control device 91 may adjust the state of the rolling rolls 82a to 82g and the rolling rolls 82a arranged at the upper side. 82g, use a smaller benchmark. In the annealing space 80, the calender rolls 82a to 82g disposed above the upper portion are likely to deteriorate due to high temperature. Therefore, the amount of torque fluctuation of the rolling rolls 82a to 82g can be effectively reduced by more frequently adjusting the state of the rolling rolls 82a to 82g disposed above.

As another example, the control device 91 can also replace the torque variation amount in the calender roll. When the maximum value of the time change amount of the torque during the period of the rotation of 82a to 82g exceeds the reference value, the state of the rolling rolls 82a to 82g is adjusted.

(6) Variation F

In the first embodiment and the second embodiment, the glass ribbon 3 is formed from the molten glass 2 by the overflow down-draw method. However, the glass ribbon 3 may be formed from the molten glass 2 by another down-draw method. For example, the glass ribbon 3 can be formed from the molten glass 2 by a re-down-down method, a flow-down method, or the like.

2‧‧‧Solid glass

3‧‧‧glass ribbon

40‧‧‧Forming device

50c‧‧‧Transfer tube

60‧‧‧Upper forming space

62‧‧‧Formed body

62a‧‧‧ Lower end of the formed body

62b‧‧‧ slots

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‧‧‧ Annealing space

82a~82g‧‧‧Cooling roller (roller)

84a~84g‧‧‧heater

86‧‧‧Insulation members

98‧‧‧cutting device

Claims (7)

A method for producing a glass substrate, which is a method for producing a glass substrate from a molten glass by an overflow down-draw method, and a transfer step of using a plurality of rolls arranged along a vertical direction And the glass ribbon is held by the roller, and the glass ribbon is conveyed to the lower side, and the measuring step is performed to measure the torque of the roller during the rotation while the glass ribbon is conveyed to the lower side. And an adjustment step of adjusting the state of the roller so that the load on the glass ribbon conveyed from each of the rollers from the downward direction is uniform based on the measured torque. The method for producing a glass substrate according to claim 1, wherein the adjusting step is such that the difference between the torques of the two rolls adjacent to each other in the conveying direction of the glass ribbon is a specific value or more, and the two rolls are The state of the above roller is adjusted in such a manner that the difference in angular velocity becomes small. The method of manufacturing a glass substrate according to claim 2, wherein the adjusting step controls a number of revolutions of the motor for rotating the roller to adjust a state of the roller. The method for producing a glass substrate according to any one of claims 1 to 3, wherein the adjusting step is a torque variation amount which is a difference between a maximum value and a minimum value of the torque in a period in which the roller rotates one time; In the case, the state of the above roller is adjusted so that the amount of torque fluctuation described above becomes small. The method of producing a glass substrate according to claim 4, wherein the adjusting step controls a contact load between the roller and the glass ribbon to adjust a state of the roller. The method for producing a glass substrate according to any one of claims 1 to 3, wherein the adjusting step adjusts a state of the roller by replacing the roller and the backup roller used in the transporting step. A glass substrate manufacturing apparatus which is formed by forming a glass substrate from molten glass by an overflow down-draw method, and has a conveying unit having a plurality of roller pairs arranged along a vertical direction While the glass ribbon is held by the pair of rollers, the roller of the pair is rotated to transfer the glass ribbon to the lower side, and the measuring unit is rotated while the glass ribbon is being conveyed to the lower side. The torque of the roller and the adjustment unit adjust the state of the roller so that the load on the glass ribbon that is conveyed from the downward direction by the respective rollers is uniform based on the measured torque.