JP6007277B2 - Glass substrate manufacturing method and glass substrate manufacturing apparatus - Google Patents

Description

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

  Conventionally, a method of manufacturing a glass substrate using a downdraw method has been used. In the downdraw method, molten glass is poured into a molded body, and then the molten glass is allowed to overflow from the molded body. The molten glass then flows down along the shaped body. Molten glass merges at the lower end of the molded body, and then leaves the molded body to become sheet-like glass (sheet glass). The sheet glass is cooled by the atmosphere in the furnace in the process of flowing down. Thereafter, the sheet glass is cut into a desired size and further processed into a glass substrate. For example, in Patent Document 1, for the purpose of manufacturing a glass substrate with good warping quality, a cooling device is provided so as to face both side portions in the width direction of the sheet glass, and until both side portions are in the vicinity of the annealing point. A technique for controlling to have a predetermined viscosity in the temperature range is disclosed.

Japanese Patent No. 5154713

  However, when both sides of the sheet glass in the width direction are cooled, the difference between the viscosity of both sides and the viscosity of the central region sandwiched between both sides increases, and stress is generated between the both sides and the central region. In some cases, warping and distortion may occur at the boundary between both side portions and the central region.

  Then, this invention aims at providing the manufacturing method of the glass substrate which can suppress the distortion of a glass substrate, and the manufacturing apparatus of a glass substrate by controlling the viscosity of the both sides and center area | region of a glass substrate. To do.

One embodiment of the present invention is a method for manufacturing a glass substrate according to the present invention by a downdraw method. In the downdraw method, molten glass is overflowed from a molded body and formed into a sheet glass, and the sheet glass is cooled while being stretched downward. When the sheet glass is in the temperature region from the temperature higher than the softening point to the vicinity of the annealing point after the sheet glass is separated from the molded body , a side including the edges, in a thin central region thickness than the side sandwiched by the side, pressure to give a tension toward the side, resulting in boundary between the side and the central region stress The sheet glass is cooled so as to suppress this. The side portion of the sheet glass is a region having a bulbous shape, which is thicker than the central region, and refers to, for example, a range within 200 mm from the edge in the width direction of the sheet glass. The central region of the sheet glass refers to a range sandwiched between the side portions.

In this method for producing a glass substrate, when the temperature of the sheet glass away from the molded body is in a temperature range from a temperature higher than the softening point to the vicinity of the annealing point, the sheet glass has a low viscosity and sufficient fluidity. Because it has, it is easy to shrink. The phrase “in the temperature range from the temperature higher than the softening point to the vicinity of the annealing point” means that at least a part of the sheet glass is in this temperature range. The viscosity of the sheet glass directly below the molded body ^is preferably 10 ^5.7 ~10 7.5 Poise. The annealing point refers to the temperature of glass having a viscosity of 10 ¹³ poise (1 poise = 1 dPa · sec). The softening point refers to the temperature of a glass having a viscosity of 10 ^7.5 Poise. Further, the vicinity of the annealing point means within the range of ± 20 ° C. from the annealing point including the annealing point.

Specifically, the sheet glass is cooled in the width direction of the sheet glass by cooling the sheet glass while maintaining the viscosity of the side portion of the sheet glass away from the molded body within the range of 10 ^9.0 to 10 ^14.5 Poise. Shrinkage is suppressed. If the viscosity of the sides of the sheet glass is less than 10 ^{9.0 Poise,} since the sheet glass is easily deformed, shrinkage in the width direction of the sheet glass is prone. Moreover, when the viscosity of the side part of a sheet glass exceeds 10 ^14.5 Poise, it cannot endure the stress which generate | occur | produces inside a sheet glass, and sheet glass may crack. Therefore, it is preferable to cool while maintaining the viscosity of the sides of the sheet glass ¹⁰ from 9.0 ^{to 10} 14.5 within the scope of Poise. Moreover, it is more preferable to cool by maintaining the viscosity of the side part of the sheet glass within the range of 10 ^10.0 to 10 ^14.5 Poise.

Then, by cooling the sheet glass while maintaining the viscosity of the sides of the sheet glass away from the molded article 10 ^{from 9.0 to 10} 14.5 within the ^Poise, shrinkage in the width direction of the sheet glass is suppressed Therefore, the tension is applied in the width direction of the sheet glass toward both sides of the sheet glass. In addition, it is preferable to hold | maintain a sheet glass with the cooling roller which let air pass inside. Thereby, the shrinkage | contraction to the width direction of sheet glass is suppressed more effectively.

  Moreover, it is preferable to cool so that the viscosity of the side part of sheet glass may become high along a flow-down direction. Thereby, since the side part of a sheet glass is cooled in steps or continuously, it is prevented that a sheet glass is cooled too much at a time and cracks.

Further, (In terms of temperature, e.g., 850 ℃ ~1120 ℃) viscosity ¹⁰ 5.7 ^{to 10} 9.67 Poise range of the central region of the sheet glass away from the molded article by cooling and maintained in The viscosity difference (temperature difference) between the side portion and the central region is reduced, and warpage, distortion, and the like occurring at the boundary between the side portion and the central region are suppressed. When the viscosity of the central region of the sheet glass is less than 10 ^5.7 poise, stress is likely to occur because the viscosity difference (temperature difference) between the side portion and the central region is large. Moreover, when the viscosity of the center area | region of sheet glass exceeds 10 ^9.67 Poise, it cannot endure the stress which generate | occur | produces inside sheet glass, and sheet glass may break. Therefore, it is preferable to cool while maintaining the viscosity of the central region of the sheet glass in the range of ¹⁰ 5.7 ^~10 9.67 Poise. It is more preferable to cool while maintaining the viscosity of the central region of the sheet glass ¹⁰ 7.5 ^{to 10} 9.67 Poise range of.

Since the sheet glass immediately after leaving the molded body is in a state where it is most easily contracted, the shrinkage in the width direction can be effectively suppressed by rapid cooling. Furthermore, by maintaining the viscosity difference between the viscosity of the side portion of the sheet glass away from the molded body and the viscosity of the central region so as to be equal to or less than the reference value, cooling occurs in the vicinity of the boundary between the side portion and the central region. Since the stress is suppressed, warpage, distortion, and the like generated in the sheet glass are more effectively suppressed. Within a first range of viscosities in this case sides ¹⁰ 9.0 ^{to 10} 14.5 Poise, the viscosity of the central region is in the ¹⁰ 5.7 ^{to 10} 9.67 in the second range of Poise, the reference The value is preferably the viscosity difference between the first viscosity at the side and the second viscosity at the central region. Therefore, the reference value ^is a ^{10 9.0 (≒ 10 9.0 -10 5.7} ) less than Poise. Further, the reference value is in the range of less than 10 ^14.5 (≈10 ^14.5 −10 ^9.67 ) Poise to 0 Poise.

Further, the viscosity of the sheet glass immediately below the molded body is 10 ^5.7 to 10 ^7.5 Poise, and the viscosity of the side portion of the sheet glass is in the range of 10 ^9.0 to 10 ^10.5 Poise. The sheet glass is rapidly cooled, and after the sheet glass is rapidly cooled, the side portion has a viscosity within the range of 10 ^10.5 to 10 ^14.5 Poise by lowering the cooling ability than the rapid cooling and cooling the side portion. It is preferable to maintain.

By rapidly cooling the sheet glass having a viscosity of 10 ^5.7 to 10 ^7.5 Poise directly under the molded body so that the viscosity of the side portion is in the range of 10 ^9.0 to 10 ^10.5 Poise, Shrinkage of the sheet glass in the width direction can be suppressed while preventing breakage of the glass. In addition, after the sheet glass is rapidly cooled, the sheet glass is further cooled so that the side viscosity is within the range of 10 ^10.5 to 10 ^14.5 Poise, thereby preventing the sheet glass from cracking. The shrinkage in the width direction can be continuously suppressed.

In addition, the sheet glass having a viscosity of 10 ^5.7 to 10 ^7.5 Poise immediately below the molded body may be rapidly cooled so that the viscosity of the side portion is in the range of 10 ^9.5 to 10 ^10.5 Poise. More preferably, it is more preferable that the side portion is rapidly cooled so that the viscosity of the side portion is in the range of 10 ^10.0 to 10 ^10.5 Poise. Further, after the sheet glass is rapidly cooled, it is more preferable that the sheet glass is cooled to a side viscosity of 10 ^11.0 to 10 ^14.5 Poise, and the side viscosity is 10 ^11.5 to 10 ^14. More preferably, it is cooled within the range of ^.5 Poise.

Further, the sheet glass having a viscosity of 10 ^5.7 to 10 ^7.5 Poise immediately below the molded body may be rapidly cooled so that the viscosity of the central region is within the range of 10 ^5.7 to 10 ^7.5 Poise. More preferably, quenching is further performed so that the viscosity in the central region is in the range of 10 ^6.5 to 10 ^7.5 Poise. Further, after quenching the sheet glass, a sheet glass, it is more preferable that the viscosity of the central region is cooled to ¹⁰ 7.5 ^{to 10} 9.67 Poise within the range of 9.0 viscosity of the central region ^{10 to 109} More preferably, cooling to within the range of ^.67 Poise.

Further, using a cooling roller, the sheet glass directly below the molded body, the viscosity of the sides is preferably quenching to be ¹⁰ 9.0 ^{to 10} 10.5 within the scope of Poise. By bringing the cooling roller into contact with the sheet glass, heat can be removed from the sheet glass in a short time due to heat conduction, so that the sheet glass can be rapidly cooled. Moreover, shrinkage | contraction to the width direction can further be suppressed by hold | maintaining sheet glass with a cooling roller.

Moreover, the sheet glass rapidly cooled by the cooling roller is cooled by using a cooling unit that is installed apart from the sheet glass, so that the viscosity of the side portion of the sheet glass is 10 ^10.5 to 10 ^14.5 Poise. It is preferable to maintain within the range. Thereby, since the sheet glass is continuously cooled by the radiant heat transfer by the cooling unit installed separately from the sheet glass, it is possible to prevent the surface of the sheet glass from being excessively cooled and cracked. A plurality of cooling units are preferably provided. Thereby, it is suppressed effectively that the surface of sheet glass is cooled too much, and the crack of sheet glass can be controlled effectively.

  Moreover, it is preferable to perform a plate | board thickness equalization process and a curvature reduction process in the temperature area | region until the temperature of sheet glass becomes from the temperature higher than a softening point to the annealing point vicinity. The plate thickness equalizing step is a step for making the plate thickness of the sheet glass uniform in the width direction. A warp reduction process is a process for reducing the curvature of a sheet glass after a plate | board thickness equalization process.

  In the plate thickness equalizing step, it is preferable that the temperature distribution in the width direction in the central region of the sheet glass is made uniform, and the temperature on both sides of the sheet glass is made lower than the temperature in the central region. As a result, the side portion of the sheet glass is cooled so that shrinkage in the width direction is suppressed, and the central region of the sheet glass is cooled so that the plate thickness is uniform. It can be made uniform. Here, the central region of the sheet glass is a region including a portion to be uniformed, and the side portion of the sheet glass is a region including a portion to be cut after manufacturing.

  In addition, it is preferable that a plate | board thickness equalization process is performed immediately after the sheet glass leaves | separates from a molded object, and it is preferable to be performed until the temperature of a sheet glass is cooled to a softening point. Thereby, plate | board thickness can be made more uniform.

In the warp reduction process, the temperature distribution in the width direction of the sheet glass is made lower than that in the plate thickness equalization process, and the width direction of the sheet glass extends from the center part in the width direction of the center region of the sheet glass toward the side part. It is preferable to form a temperature gradient. The central portion of the sheet glass is a region that is a product region in which the plate thickness in the range sandwiched between the side portions is substantially constant, for example, a portion in a range that is 200 mm or more away from the edge in the width direction of the sheet glass.
And it can cool so that a tensile stress may always work in the center part of the width direction of a sheet glass by cooling so that the temperature gradient of a sheet glass may reduce as the temperature of a sheet glass goes to a strain point. Thereby, it can cool, maintaining the plate | board thickness of sheet glass uniformly, and the curvature of sheet glass can be reduced. The “temperature gradient” of “the temperature gradient of the sheet glass is reduced” is a value obtained by subtracting the temperature of the edge portion in the width direction of the sheet glass from the temperature in the center portion of the sheet glass in the width direction. The absolute value of the value divided by half the width.

  Moreover, it is preferable that a plate | board thickness equalization process makes the temperature distribution of the width direction in the center area | region of sheet glass uniform, and makes temperature of the both sides of sheet glass lower than the temperature of a center area | region. In the warp reduction process, it is preferable that the temperature distribution in the width direction of the sheet glass is made lower than in the plate thickness equalization process, and a temperature gradient is formed in the width direction of the sheet glass from the center of the central portion toward the side portion.

In the warp reduction step, it is preferable to cool the sheet glass toward the vicinity of the strain point of the sheet glass so that the temperature gradient formed in the width direction of the sheet glass is reduced. The strain point means the temperature of the glass having a viscosity of 10 ^14.5 poise, and the vicinity of the strain point means a predetermined temperature region including the strain point. The predetermined temperature region is a region from “(slow cooling point + strain point) / 2” to “strain point−50 ° C.”.
By cooling the sheet glass to the strain point so that the temperature gradient formed in the warp reduction process is reduced, the cooling amount at the center in the width direction of the sheet glass is the cooling amount at both sides in the width direction of the sheet glass. Bigger than. Thereby, since the volumetric shrinkage of the sheet glass increases from the side part in the width direction of the sheet glass toward the center part, tensile stress acts on the center part of the sheet glass. In particular, a tensile stress acts on the central portion of the sheet glass in the flow direction and the width direction of the sheet glass. In addition, it is preferable that the tensile stress acting in the flow direction of the sheet glass is larger than the tensile stress acting in the width direction of the sheet glass. Since the sheet can be cooled while maintaining the flatness of the sheet glass by the tensile stress, the warp of the sheet glass can be reduced.

The apparatus for manufacturing a glass substrate according to the present invention includes a molded body, a first heat treatment unit, and a second heat treatment unit. The molded body has a pair of top portions, a lower end portion, and a pair of surfaces. The pair of surfaces extends from the pair of top portions to the lower end portions. After a molten glass overflows from a pair of top part, a molded object is made to flow down along a pair of surface, and is made to join at a lower end part, and shape | molds sheet glass. The first heat treatment unit includes a side part including edges on both sides in the width direction of the sheet glass, and the side part sandwiched between the side parts when the sheet glass separated from the molded body is in a temperature region higher than the softening point. of the more thick thin central region, the viscosity of the sides of the heat treatment I line of the side to ¹⁰ 9.0 ^~10 14.5 Poise. The second heat treatment unit performs heat treatment of the side portion and the central region when the sheet glass is in a temperature region from the vicinity of the softening point to the vicinity of the annealing point. Further, the second heat treatment unit applies tension toward the side portion, cools the sheet glass so as to suppress stress generated at a boundary between the side portion and the central region, and in cooling the sheet glass, , the viscosity of said side and to cool maintained ¹⁰ 9.0 ^{to 10} 14.5 within the Poise, cooling the viscosity of the central region ¹⁰ 5.7 ^{to 10} 9.67 Poise range of. Thereby, the improvement of the production amount of a glass substrate and the improvement of curvature quality are realizable. The vicinity of the softening point is a temperature range from a temperature including the softening point and adding 100 ° C. to the softening point of the sheet glass to a temperature obtained by subtracting 100 ° C. from the softening point of the sheet glass.

  According to the present invention, the distortion of the glass substrate can be suppressed by controlling the viscosity of the both side portions and the central region of the glass substrate.

It is a figure which shows an example of the process of the manufacturing method of a glass substrate. It is a schematic block diagram of a glass substrate manufacturing apparatus. It is a schematic block diagram (sectional drawing) of a shaping | molding apparatus. It is a schematic block diagram (side view) of a shaping | molding apparatus. FIG. 5 is a VV cross-sectional view (cross-sectional view of the central cooling unit) of FIG. 4. It is a schematic plan view of a lower air cooling unit. It is VII-VII sectional drawing (sectional drawing of a side part cooling unit) of FIG. It is a perspective view of a lower water cooling unit. It is a figure which shows each mechanism connected to a control apparatus and a control apparatus. It is a figure which shows the atmospheric temperature controlled based on the several temperature profile. (A), (b) is a figure which shows an example of a 1st temperature profile. It is a figure which shows one shape which planarly viewed the sheet glass shape | molded with a shaping | molding apparatus.

(1) Overall Configuration In the method for producing a glass substrate according to the present embodiment, for example, a glass substrate for flat panel display (for example, a glass substrate for liquid crystal display, a glass substrate for plasma display, a glass substrate for organic EL display), a cover glass. A glass substrate on which electronic devices such as a glass substrate for tempered glass such as a magnetic disk, a glass substrate wound up in a roll, and a semiconductor wafer are laminated is manufactured. This glass substrate is manufactured using, for example, a downdraw method.

  With reference to FIG. 1 and FIG. 2, a plurality of steps (a method for manufacturing a glass substrate) until a glass substrate is manufactured and a glass substrate manufacturing apparatus 100 used in the plurality of steps will be described.

  The plurality of steps include a dissolving step S1, a clarifying step S2, a forming step S3, a cooling step S4, and a cutting step S5.

  The melting step S1 is a step in which the glass raw material is melted. As shown in FIG. 2, the glass raw material is put into a melting apparatus 11 arranged upstream. The glass raw material is melted by the melting device 11 to become a molten glass FG. The molten glass FG is sent to the refining device 12 through the upstream pipe 23.

  The clarification step S2 is a step of removing bubbles in the molten glass FG. The molten glass FG from which bubbles have been removed in the refining device 12 is then sent to the forming device 40 through the downstream pipe 24.

  The forming step S3 is a step of forming the molten glass FG into a sheet-like glass (sheet glass) SG. Specifically, the molten glass FG overflows from the molded body 41 after being sent to the molded body 41 included in the molding apparatus 40. The overflowed molten glass FG flows down along the surface of the molded body 41. Thereafter, the molten glass FG joins at the lower end of the molded body 41 to become a sheet glass SG.

  The cooling step S4 is a step of cooling (slow cooling) the sheet glass SG. The glass sheet is cooled to a temperature close to room temperature through the cooling step S4. Note that the thickness (plate thickness) of the glass substrate, the amount of warpage of the glass substrate, and the amount of strain of the glass substrate are determined according to the cooling state in the cooling step S4.

  The cutting step S5 is a step of cutting the sheet glass SG having a temperature close to room temperature into a predetermined size.

  In addition, the sheet glass SG (glass piece) cut | disconnected by the predetermined magnitude | size becomes a glass substrate through processes, such as end surface processing after that.

  Hereinafter, the configuration of the molding apparatus 40 will be described with reference to FIGS. In the present embodiment, the width direction of the sheet glass SG means a direction that intersects the direction (flow direction or flow direction) in which the sheet glass SG flows, that is, the horizontal direction.

(2) Configuration of Molding Apparatus First, a schematic configuration of the molding apparatus 40 is shown in FIGS. FIG. 3 is a cross-sectional view of the molding apparatus 40. FIG. 4 is a side view of the molding apparatus 40. The molding device 40 mainly includes a molded body 41, a partition member 50, a cooling roller 51, a cooling unit 60, a pulling roller 81, and a cutting device 90. Furthermore, the shaping | molding apparatus 40 is provided with the control apparatus 91 (refer FIG. 9). The control device 91 controls the drive unit of each component included in the molding device 40. Hereinafter, each configuration included in the molding apparatus 40 will be described.

(2-1) Molded Body The molded body 41 molds the molten glass FG into a sheet-like glass (sheet glass SG) by overflowing the molten glass FG.

  As shown in FIG. 3, the molded body 41 has a substantially pentagonal shape (a shape similar to a wedge shape) in cross-sectional shape. The substantially pentagonal tip corresponds to the lower end portion 41 a of the molded body 41.

Moreover, the molded object 41 has the inflow port 42 in the 1st end part (refer FIG. 4). The inlet 42 is connected to the above-described downstream pipe 24, and the molten glass FG that has flowed out of the refining device 12 is poured into the molded body 41 from the inlet 42. A groove 43 is formed in the molded body 41. The groove 43 extends in the longitudinal direction of the molded body 41. Specifically, the groove 43 extends from the first end to the second end that is the end opposite to the first end. More specifically, the groove 43 extends in the left-right direction in FIG. The groove 43 is deepest in the vicinity of the inlet 42 and is formed so as to become gradually shallower as it approaches the second end. The molten glass FG poured into the molded body 41 overflows from the pair of top portions 41 b and 41 b of the molded body 41 and flows down along the pair of side surfaces (surfaces) 41 c and 41 c of the molded body 41. Thereafter, the molten glass FG joins at the lower end 41a of the molded body 41 to become the sheet glass SG. Note that the sheet glass SG has a viscosity of, for example, 10 ^5.7 to 10 ^7.5 Poise just below the molded body 41.

(2-2) Partition member The partition member 50 is arrange | positioned in the vicinity of the confluence | merging point of molten glass FG. Moreover, as shown in FIG. 3, the partition member 50 is arrange | positioned at the thickness direction both sides of the molten glass FG (sheet glass SG) merged at the merge point. The partition member 50 is a heat insulating material. The partition member 50 blocks the movement of heat from the upper side to the lower side of the partition member 50 by partitioning the upper atmosphere and the lower atmosphere at the joining point of the molten glass FG.

(2-3) Cooling roller The cooling roller 51 is a unit that heat-treats both side portions of the sheet glass SG. The cooling roller 51 is disposed immediately below the partition member 50. Moreover, the cooling roller 51 is arrange | positioned at the thickness direction both sides of the sheet glass SG, and the width direction both sides of the sheet glass SG. That is, the cooling roller 51 heat-treats the sheet glass SG separated from the molded body 41 immediately below the molded body 41. The cooling rollers 51 disposed on both sides in the thickness direction of the sheet glass SG operate in pairs. Therefore, both sides of the sheet glass SG are sandwiched between two pairs of cooling rollers 51, 51,.

The cooling roller 51 is air-cooled by an air-cooling tube passed through the inside. The cooling roller 51 contacts the side part (ear part) of the sheet glass SG, and quenches the side part of the sheet glass SG by heat conduction (rapid cooling process). The cooling roller 51 rapidly cools the side portion of the sheet glass so that the viscosity of the side portion of the sheet glass SG becomes, for example, 10 ^9.0 Poise or more.

  In addition, cooling of the side part of the sheet glass SG by the cooling roller 51 affects the uniformity of the thickness of the sheet glass SG.

(2-4) Cooling unit The cooling unit 60 is a unit that performs heat treatment of the sheet glass SG. Specifically, the cooling unit 60 is a unit that cools the sheet glass SG in a temperature region in which the temperature in the central region of the sheet glass SG is higher than the softening point to the vicinity of the annealing point. The cooling unit 60 is disposed below the partition member 50 and on the top plate 80 a of the slow cooling furnace 80. The cooling unit 60 cools the upstream region of the sheet glass SG (upstream region cooling step). The upstream region of the sheet glass SG is a region of the sheet glass SG in which the temperature of the central portion (central region) of the sheet glass SG is above the annealing point. Moreover, the center part of the sheet glass SG is a width direction center part of the sheet glass SG, and is an area including the effective range of the sheet glass SG and the vicinity thereof. In other words, the center part of the sheet glass SG is a part sandwiched between both side parts of the sheet glass SG. Specifically, the upstream region includes a first temperature region and a second temperature region. In the first temperature region, the temperature in the central region of the sheet glass SG (more specifically, the temperature in the center in the width direction of the central region) is directly below the lower end portion 41a of the molded body 41 and in the vicinity of the softening point higher than the softening point. It is the area | region of the sheet glass SG until it becomes. Further, the second temperature region is a temperature from the vicinity of the softening point to the vicinity of the annealing point where the temperature of the central region of the sheet glass SG (more specifically, the temperature at the center of the width direction of the central region) is higher than the softening point. It is a temperature range. That is, the cooling unit 60 cools the sheet glass SG so that the temperature of the central region of the sheet glass SG approaches the annealing point. Thereafter, the central region of the sheet glass SG is cooled to a temperature near room temperature through a slow cooling point and a strain point in a slow cooling furnace 80 described later (downstream region cooling step (slow cooling step)).

  The cooling unit 60 cools the sheet glass SG based on a plurality of temperature profiles so that the distortion, thickness, and warpage of the sheet glass SG become desired values. That is, in the upstream region, a plurality of temperature profiles are set along the flow direction of the sheet glass SG. Here, the temperature profile is a temperature distribution along the width direction of the sheet glass SG with respect to the ambient temperature in the vicinity of the sheet glass SG. In other words, the temperature profile is the distribution of the target ambient temperature. The cooling roller 51 and the cooling unit 60 described above control the ambient temperature so as to realize a temperature profile.

  The cooling unit 60 includes a plurality of units. A plurality of temperature profiles are realized by a plurality of units being independently controlled. Specifically, the cooling unit 60 includes a central cooling unit 61 and two side cooling units 71 and 71. As shown in FIG. 4, the center part cooling unit 61 is arrange | positioned in the width direction center of the shaping | molding apparatus 40, and cools the center part of the sheet glass SG (center part cooling process). The center part cooling unit 61 is arrange | positioned at the thickness direction both sides of the sheet glass SG. The side cooling units 71 are arranged at positions adjacent to the central cooling unit 61, respectively. That is, the side part cooling unit 71 is arrange | positioned so that it may oppose on both sides of the thickness direction of the sheet glass SG on both sides of the sheet glass SG, and the side part (ear part) and side part periphery of the sheet glass SG are cooled (side). Part cooling step). Moreover, the center part cooling unit 61 and the side part cooling unit 71 are each arrange | positioned in the position close | similar to the sheet glass SG.

  Hereinafter, the configuration of the central cooling unit 61 and the configuration of the side cooling unit 71 will be described in detail with reference to FIGS. In the cross-sectional views shown in FIGS. 5 and 7, only the configuration on one side of each cooling unit 61, 71 is shown with respect to the passage position (dashed line W) of the sheet glass SG. Moreover, in the following description, back means the direction away from the surface of the sheet glass SG.

(2-4-1) Center part cooling unit The center part cooling unit 61 cools the center part of the sheet glass SG in steps along a flow-down direction (center part cooling process). The central cooling unit 61 is composed of an upper air cooling unit 62 and lower air cooling units 63a and 63b. The upper air cooling unit 62 and the two lower air cooling units 63a and 63b are arranged along the flow-down direction of the sheet glass SG. Specifically, two lower air cooling units 63 a and 63 b are arranged below the upper air cooling unit 62. As shown in FIG. 5, the upper air cooling unit 62 and the two lower air cooling units 63 a and 63 b are connected to each other via a heat insulating member 93. The heat insulating member 93 is between a space (first space SP1) formed inside the upper air cooling unit 62 and a space (second space SP2) formed inside the lower air cooling unit 63a disposed above. The movement of heat and the movement of heat between the second space SP2 and the space (third space SP3) formed by the lower air cooling unit 63b disposed below are blocked. The upper air cooling unit 62 and the lower air cooling units 63a and 63b can be independently controlled.

a) Upper air cooling unit The upper air cooling unit 62 is located immediately below the partition member 50 described above. The upper air cooling unit 62 is a unit for realizing a temperature profile in a region that determines the thickness of the sheet glass SG. The region that determines the thickness of the sheet glass SG corresponds to the first temperature region described above. The upper air cooling unit 62 is controlled so that the thickness of the sheet glass SG is uniform in the width direction (first center cooling step). The upper air cooling unit 62 mainly includes an upper cooling adjustment plate 21 and a rear water cooling unit 22. The upper air cooling unit 62 maintains the viscosity of the central portion (central region) of the sheet glass SG within a range of, for example, 10 ^5.7 to 10 ^7.5 Poise (temperature is about 1000 ° C. to 1120 ° C.). The center part (central area | region) of sheet glass is cooled.

a-1) Upper cooling adjustment plate The upper cooling adjustment plate 21 extends in the width direction (that is, the horizontal direction) of the sheet glass SG. The length in the longitudinal direction of the upper cooling adjustment plate 21 is a length corresponding to a portion excluding the side portion of the sheet glass SG and the periphery of the side portion of the sheet glass SG. Therefore, the length of the upper cooling adjustment plate 21 is shorter than the length in the width direction of the sheet glass SG.

  The upper cooling adjustment plate 21 includes a first ceiling portion 211, a first bottom portion 212, and a first facing portion 213. The first ceiling portion 211 is a portion that becomes the ceiling of the upper air cooling unit 62. The first bottom portion 212 is a portion that becomes the bottom of the upper air cooling unit 62. A portion of the upper cooling adjustment plate 21 excluding the first ceiling portion 211 and the first bottom portion 212 is a first facing portion 213.

  In the present embodiment, a metal member is used as the upper cooling adjustment plate 21. In particular, the first facing portion 213 is preferably a member having heat resistance of 600 ° C. or higher in the atmosphere. The first facing portion 213 is preferably a member having a thermal conductivity of at least 30 W / m · K or more and an emissivity characteristic of 0.85 or more in the operating temperature range. In the present embodiment, pure nickel (thermal conductivity: 79.3 W / m ° C.) is used as the first facing portion 213.

  The first facing portion 213 is bent as shown in FIG. Specifically, the first facing portion 213 is a channel (grooved steel). The 1st opposing part 213 has the surface (1st opposing surface) 213a which opposes the sheet glass SG. The upper cooling adjustment plate 21 forms a first space SP1 together with a side wall (not shown).

a-2) Rear Water Cooling Unit The rear water cooling unit 22 is a unit that water-cools the air in the first space SP1. The rear water cooling unit 22 is disposed behind the upper cooling adjustment plate 21, and water-cools the first space SP1 from the rear. The first space SP1 is closed by the rear water cooling unit 22. The rear water cooling unit 22 is connected to a first cooling water supply unit (not shown). The amount of water supplied from the first cooling water supply unit to the rear water cooling unit 22 is adjusted by the first cooling water supply valve 22a (see FIG. 9).

b) Lower air cooling unit The lower air cooling units 63a and 63b are arranged below the upper air cooling unit 62 as described above. The lower air cooling units 63a and 63b are units for realizing a temperature profile in a region where the control of the warp amount of the sheet glass SG is started. Here, the area | region which starts control of the curvature amount of the sheet glass SG is corresponded to the above-mentioned 2nd temperature area | region.

The lower air cooling unit 63a controls the temperature of the sheet glass SG on the upstream side of the second temperature region (second central part cooling step). The lower air cooling unit 63b controls the temperature of the sheet glass SG on the downstream side of the second temperature region (third central portion cooling step). The lower air cooling unit 63a has a second space SP2, and the lower air cooling unit 63b has a third space SP3. The lower air cooling units 63a and 63b have the same configuration. Therefore, the configuration of the lower air cooling unit 63a will be described below. As shown in FIG. 6, the lower air cooling unit 63 a mainly includes a lower cooling adjustment plate 31 and a temperature control unit 32. Lower cooling units 63a, 63b, the central portion of the sheet glass SG viscosity (central region), for example, ¹⁰ 7.5 ^{to 10} 9.67 Poise (at temperature, 850 ° C. to 1000 ° C. approximately) maintained within the range of Thus, the center part (center area | region) of sheet glass is cooled.

b-1) Lower cooling adjustment plate The lower cooling adjustment plate 31 has the same configuration as the upper cooling adjustment plate 21 described above. That is, the lower cooling adjustment plate 31 extends in the width direction (that is, the horizontal direction) of the sheet glass SG, and the length in the longitudinal direction is the same as the length in the longitudinal direction of the upper cooling adjustment plate 21.

  Further, the lower cooling adjustment plate 31 includes a second ceiling portion 311, a second bottom portion 312, and a second facing portion 313. The 2nd ceiling part 311 is a part used as the ceiling of the lower air cooling unit 63a, and the 2nd bottom part 312 is a part used as the bottom of the lower air cooling unit 63a. A portion of the lower cooling adjustment plate 31 excluding the second ceiling portion 311 and the second bottom portion 312 is the second facing portion 313.

  Similarly to the upper cooling adjustment plate 21, a metal member is used for the lower cooling adjustment plate 31. In particular, the second facing portion 313 is preferably a member having a heat resistance of 600 ° C. or higher in the atmosphere, and further has a thermal conductivity of at least 30 W / m · K, and is 0.85 in the operating temperature range. A member having the above emissivity characteristics is preferable. In the present embodiment, pure nickel (thermal conductivity: 79.3 W / m ° C.) is used as the second facing portion 313.

  In addition, the second facing portion 313 is subjected to a bending process (see FIG. 5), similarly to the first facing portion 213. That is, the second facing portion 313 is also a channel (grooved steel), and the second facing portion 313 has a surface (second facing surface) 313a facing the sheet glass SG. The lower cooling adjustment plate 31 and the side wall 37 form a second space SP2.

b-2) Temperature Control Unit The temperature control unit 32 is a unit for adjusting the temperature of the lower cooling adjustment plate 31. The temperature control unit 32 mainly includes a temperature adjustment pipe 33 and a plurality of gas supply units 34a, 34b, and 34c.

  The temperature adjustment pipe 33 flows a fluid for cooling or heating the entire lower cooling adjustment plate 31. Here, the fluid flowing through the temperature adjustment pipe 33 is a gas (for example, air or an inert gas such as nitrogen). As shown in FIG. 6, the temperature adjustment pipe 33 is disposed along the longitudinal direction of the lower cooling adjustment plate 31. A plurality of air outlets (nozzles) 331, 331,... Are uniformly formed in the temperature adjustment pipe 33. Specifically, the air outlet 331 is formed at a symmetrical position with respect to the center line C of the temperature adjusting pipe 33. The blower outlet 331 is provided in the position which opposes the back surface of the 2nd opposing surface 313a. That is, the gas blown from the blowout port 331 is blown to the back surface of the second facing surface 313a.

  The temperature adjustment pipe 33 has an internal space. The internal space is internally divided into three. Thereby, the temperature adjustment pipe 33 has the 1st side part adjustment part 33a, the 2nd side part adjustment part 33b, and the center part adjustment part 33c. The first side adjustment part 33 a is a part for adjusting the temperature of the first side part of the lower cooling adjustment plate 31. The second side adjustment part 33 b is a part for adjusting the temperature of the second side part of the lower cooling adjustment plate 31. The second side is a side on the opposite side of the first side. The center adjustment part 33 c is a part for adjusting the temperature of the center part in the width direction of the lower cooling adjustment plate 31. The temperature adjustment pipe 33 is connected to a plurality of introduction pipes 35a, 35b, 35c, and 35c. The introduction pipes 35a, 35b, 35c, and 35c are pipes that send a gas serving as a heat exchange medium to the temperature adjustment pipe 33. Specifically, the first introduction pipe 35a is connected to the first side adjustment section 33a of the temperature adjustment pipe 33, and the second introduction pipe 35b is connected to the second side adjustment section 33b of the temperature adjustment pipe 33. In addition, two third introduction pipes 35 c and 35 c are connected to the center adjustment part 33 c of the temperature adjustment pipe 33. The first introduction pipe 35a, the second introduction pipe 35b, and the third introduction pipe 35c send the gas supplied from different gas supply units 34a, 34b, and 34c to the temperature adjustment units 33a, 33b, and 33c, respectively. Specifically, as shown in FIG. 6, the first introduction pipe 35a is connected to the first gas supply unit 34a. The amount of gas sent from the first gas supply unit 34a to the first introduction pipe 35a is adjusted by the first gas supply valve 36a. The second introduction pipe 35b is connected to the second gas supply unit 34b. The amount of gas sent from the second gas supply unit 34b to the second introduction pipe 35b is adjusted by the second gas supply valve 36b. Further, the two third introduction pipes 35c and 35c are connected to the third gas supply unit 34c. The amount of gas sent from the third gas supply unit 34c to the third introduction pipes 35c, 35c is adjusted by the third gas supply valve 36c.

  The flow of the gas blown to the lower cooling adjustment plate 31 is controlled so that the gas flows in the direction d2 opposite to the blowing direction d1 after being blown to the lower cooling adjustment plate 31. By controlling the gas blown out from the blowout port 331 to flow in the direction d2 before flowing in the longitudinal direction of the lower cooling adjustment plate 31, the gas blown out from the one blowout port 331 becomes another blowout port. It is configured not to affect the flow direction d1 of the gas blown from 331. The gas flowed in the direction d2 is released out of the furnace.

(2-4-2) Side Cooling Unit The side cooling unit 71 is configured so that the side portion of the sheet glass SG rapidly cooled by the cooling roller 51 and the side portion periphery of the sheet glass SG are in the flow-down direction of the sheet glass SG. Cool continuously or stepwise (side cooling process). The side cooling unit 71 operates with a cooling ability lower than that of the cooling roller 51. In other words, the amount of heat taken from the side portion of the sheet glass SG by the side cooling unit 71 is smaller than the amount of heat taken from the side portion of the sheet glass SG by the cooling roller 51. As described above, the side cooling units 71 are disposed on both sides of the central cooling unit 61 (see FIG. 4). The side cooling unit 71 is disposed close to the surface of the sheet glass SG. The side cooling unit 71 cools the side portion of the sheet glass so as to maintain the viscosity of the side portion of the sheet glass SG within a range of, for example, 10 ^9.0 to 10 ^14.5 Poise.

  As shown in FIG. 7, the side cooling unit 71 includes an upper water cooling unit 72 and a lower water cooling unit 73. The upper water cooling unit 72 and the lower water cooling unit 73 are arranged along the flow-down direction of the sheet glass SG. Further, the upper water cooling unit 72 and the lower water cooling unit 73 are independently controlled. The cooling roller 51 corresponds to a first heat treatment unit that performs heat treatment on the side portion of the sheet glass, and the central portion cooling unit 61 and the side portion cooling unit 71 correspond to a second heat treatment unit that performs heat treatment on the side portion. .

a) Upper water cooling unit The upper water cooling unit 72 is a unit for realizing a temperature profile in a region that affects the adjustment of the thickness and / or the amount of warpage of the sheet glass SG (first side cooling step). As shown in FIG. 7, the upper water cooling unit 72 is located directly below the cooling roller 51 described above. The upper water cooling unit 72 is placed on a top plate 735 of the lower water cooling unit 73 described later. The upper water cooling unit 72 is configured to be able to move closer to or away from the sheet glass SG by moving horizontally on the top plate 735 of the lower water cooling unit 73. The sheet glass SG is cooled at a required cooling rate by the upper water cooling unit 72 mainly by radiant heat transfer. Here, the required cooling rate is such that the shrinkage of the plate width of the glass SG that has passed through the cooling roller 51 is suppressed to the maximum, and the sheet glass SG is not cracked in the cooling process after the lower water cooling unit 73. Cooling rate. That is, the upper water cooling unit 72 cools the glass SG as much as possible within a range that does not adversely affect the sheet glass SG. The upper water cooling unit 72 mainly includes an upper water cooling plate 721 and an upper connection unit 722.

a-1) Upper water cooling plate The upper water cooling plate 721 is composed of a member having a relatively high thermal conductivity and excellent in oxidation resistance and heat resistance. In the present embodiment, stainless steel is used as the upper water cooling plate 721. Inside the upper water cooling plate 721, a first flow path PS1 for passing a fluid (water in this embodiment) is formed. The first flow path PS1 is configured to cool the surface (surface facing the sheet glass SG) 721a of the upper water cooling plate 721 from the back side.

  The surface of the upper water cooling plate 721 (the surface facing the sheet glass SG) is coated to increase the emissivity. The emissivity of the upper water cooling plate 721 is preferably 0.9 or more.

a-2) Upper Connection Unit The upper connection unit 722 is a unit that is disposed behind the upper water cooling plate 721 and connected to the upper water cooling plate 721. The upper connection unit 722 mainly includes an upper water supply pipe 723 and an upper drainage pipe 724. The upper water supply pipe 723 and the upper drain pipe 724 are disposed inside a fourth space SP4 formed behind the upper water cooling plate 721 (see FIG. 7). The fourth space SP4 is a space formed by a thin plate made of stainless steel, and includes a top plate, a bottom plate, and side walls. The upper water supply pipe 723 is connected to the upper part of the first flow path PS1 of the upper water cooling plate 721. Cooling water sent from a second cooling water supply unit (not shown) is sent to the upper water supply pipe 723. The second cooling water supply unit is a unit different from the first cooling water supply unit. The cooling water is supplied to the first flow path PS1 of the upper water cooling plate 721 through the upper water supply pipe 723. The amount of cooling water supplied from the second cooling water supply unit is adjusted by the second cooling water supply valve 72a (see FIG. 9). The upper drain pipe 724 is connected to the lower portion of the first flow path PS1 of the upper water cooling plate 721. The cooling water heated through the first flow path PS1 is discharged through the upper drain pipe 724.

b) Lower Water Cooling Unit The lower water cooling unit 73 is located directly below the above-described upper water cooling unit 72 as shown in FIG. The lower water cooling unit 73 is a unit for realizing a temperature profile in a region that affects the control of the amount of warp of the sheet glass SG (second side cooling step). The lower water cooling unit 73 is placed on a top plate 80a of a slow cooling furnace 80 described later. The lower water cooling unit 73 is fixed to the central cooling unit 61 described above. The sheet glass SG is cooled at a required cooling rate by the lower water cooling unit 73 mainly by radiant heat transfer. Here, the required cooling rate is a cooling rate at which the periphery of the sheet glass SG ear portion when entering the slow cooling furnace 80 becomes an optimum temperature. Further, the required cooling rate is a cooling rate at which the shrinkage of the plate width of the glass SG is suppressed to the maximum, and the sheet glass SG is not cracked in the cooling process after the slow cooling furnace 80. That is, the lower water cooling unit 73 cools the sheet glass SG to the maximum extent within a range that does not adversely affect the glass SG. The lower water cooling unit 73 mainly includes a lower water cooling plate 731 and a lower connection unit 732.

b-1) Lower water cooling plate The lower water cooling plate 731 is composed of a member having a relatively high thermal conductivity and excellent in oxidation resistance and heat resistance. In the present embodiment, stainless steel is used as the lower water cooling plate 731. Inside the lower water cooling plate 731, a second flow path PS <b> 2 for passing a fluid (water in this embodiment) is formed. The second flow path PS2 is configured to cool the surface (surface facing the sheet glass SG) 731c of the lower water cooling plate 731 from the back side.

  The emissivity of the lower water cooling plate 731 is also preferably 0.9 or more.

  Further, an upper support member 731a and a lower support member 731b are attached to the surface of the lower water cooling plate 731 as shown in FIG. The upper support member 731a and the lower support member 731b are members that make it possible to support a blocking member (such as a fiber board) on the surface of the lower water cooling plate 731. The blocking member is a member that blocks heat radiation from the lower water cooling plate 731. The upper support member 731a and the lower support member 731b support the blocking member, so that a part of the lower water cooling plate 731 is covered.

b-2) Lower connection unit The lower connection unit 732 has the same configuration as the upper connection unit 722. That is, the lower connection unit 732 is a unit that is disposed behind the lower water cooling plate 731 and is connected to the lower water cooling plate 731. The lower connection unit 732 mainly includes a lower water supply pipe 733 and a lower drainage pipe 734. The lower water supply pipe 733 and the lower drainage pipe 734 are disposed inside a fifth space SP5 formed behind the lower water cooling plate 731 (see FIG. 7). Similarly to the fourth space SP4, the fifth space SP5 is also a space formed by a thin plate made of stainless steel. The lower water supply pipe 733 is connected to the upper part of the second flow path PS2 of the lower water cooling plate 731. Cooling water sent from a third cooling water supply unit (not shown) is sent to the lower water supply pipe 733. The third cooling water supply unit is a unit different from the first cooling water supply unit and the second cooling water supply unit. The cooling water is supplied to the second flow path PS2 of the lower water cooling plate 731 through the lower water supply pipe 733. The amount of cooling water supplied from the third cooling water supply unit is adjusted by the third cooling water supply valve 73a (see FIG. 9). The lower drain pipe 734 is connected to the lower part of the second flow path PS2 of the lower water cooling plate 731. The cooling water heated through the second flow path PS2 is discharged through the lower drain pipe 734.

(2-5) Pull-down roller The pull-down roller 81 is disposed inside the slow cooling furnace 80. The slow cooling furnace 80 is a space arranged immediately below the cooling unit 60. In the slow cooling furnace 80, the temperature of the sheet glass SG is cooled from the temperature near the annealing point to the temperature near room temperature (downstream region cooling step (slow cooling step)). Moreover, the pulling-down roller 81 pulls down the sheet glass SG which passed the cooling unit 60 in the flow-down direction of the sheet glass SG. A plurality of pulling rollers 81 are arranged on both sides in the thickness direction of the sheet glass SG (see FIG. 3) and on both sides in the width direction of the sheet glass SG (see FIG. 4). The pulling roller 81 is driven by a motor (not shown). The pulling roller 81 rotates inward with respect to the sheet glass SG. The pull-down rollers 81 arranged on both sides in the thickness direction of the sheet glass SG operate in pairs, and the pair of pull-down rollers 81, 81, ... pulls the sheet glass SG downward.

(2-6) Cutting device The cutting device 90 cuts the sheet glass SG that has passed through the slow cooling furnace 80 and has been cooled to a temperature near room temperature into a predetermined size. As a result, the sheet glass SG becomes a glass piece. The cutting device 90 is disposed below the slow cooling furnace 80, and cuts the sheet glass SG at predetermined time intervals.

(2-7) Control Device The control device 91 includes a CPU, RAM, ROM, hard disk, and the like. As shown in FIG. 9, the control device 91 includes a cooling roller 51, a pulling roller 81, a first gas supply valve 36a, a second gas supply valve 36b, a third gas supply valve 36c, a first cooling water supply valve 22a, The second cooling water supply valve 72a, the third cooling water supply valve 73a, and the cutting device 90 are connected.

  The control device 91 controls driving units such as the cooling roller 51, the pulling roller 81, and the cutting device 90. The control device 91 also includes a first gas supply valve 36a, a second gas supply valve 36b, a third gas supply valve 36c, a first cooling water supply valve 22a, a second cooling water supply valve 72a, and a third cooling water supply. The opening / closing or opening degree of the valve 73a is controlled.

(3) Temperature profile and temperature control by cooling unit Next, with reference to FIG. 10, the temperature profile used in the manufacturing method of the glass substrate which concerns on this embodiment, and control of the cooling unit which implement | achieves the said temperature profile are demonstrated. To do. In FIG. 10, regions divided by broken lines indicate the arrangement of the cooling rollers 51 and the units 62, 63a, 63b, 72, 73 included in the cooling unit. Further, the curves 10b, 10c, 10e, 10f and the straight lines 10a, 10d included in the regions divided by the broken lines are the temperature profiles 20a, 20b realized by the cooling roller 51 or the units 62, 63a, 63b, 72, 73, respectively. , 20c.

  In the present embodiment, as described above, the ambient temperature is controlled independently based on a plurality of temperature profiles in the flow direction of the sheet glass SG. When the temperature of the sheet glass SG is in a predetermined temperature range, the sheet glass SG is cooled so that tension is applied toward the side of the sheet glass SG. The predetermined temperature region is a temperature region after the sheet glass SG is separated from the molded body 41 until the temperature of the sheet glass SG becomes higher than the softening point and near the annealing point. That is, the predetermined temperature region is the upstream region of the sheet glass SG described above.

As described above, the sheet glass SG after leaving the molded body 41 has a viscosity of 10 ^5.7 to 10 ^7.5 Poise. The sheet glass SG is cooled by the cooling roller 51 and the cooling unit 60, whereby the viscosity is increased. That is, the viscosity of the sheet glass SG (viscosity of the central part and the side part) increases along the flow direction of the sheet glass SG. In other words, the viscosity of the sheet glass SG increases toward the downstream side of the sheet glass SG. In the present embodiment, the side portion of the sheet glass SG is cooled by the cooling roller 51 and the side cooling unit 71 in the upstream region. Specifically, the side part of the sheet glass SG is cooled so that the viscosity is maintained within a range of, for example, 10 ^9.0 to 10 ^14.5 Poise. Further, the upper air cooling unit 62 cools the central region (central portion) of the sheet glass SG. Specifically, the central region of the sheet glass SG is cooled to be maintained within the range of viscosity for example ¹⁰ 5.7 ^~10 9.67 Poise.

  The plurality of temperature profiles are respectively set in the width direction of the sheet glass SG and the flow direction of the sheet glass SG (temperature profile setting step). Specifically, as shown in FIG. 10, the plurality of temperature profiles includes a first temperature profile 20a, a second temperature profile 20b, and a third temperature profile 20c. The first temperature profile 20a is located on the higher temperature side in the flow direction than the second temperature profile 20b. The second temperature profile 20b is located on the higher temperature side in the flow direction than the third temperature profile 20c.

  In the first temperature profile 20a, the temperature distribution in the width direction in the central region of the sheet glass SG is uniform, and the temperature on both sides in the width direction of the sheet glass SG is lower than the temperature in the central region of the sheet glass SG. Here, the uniform temperature distribution in the width direction means that the temperature distribution in the width direction is a value in a range of 0 ° C. to ± 10 ° C. with respect to a predetermined reference value (temperature). That is, based on the first temperature profile 20a, both side portions of the sheet glass SG are rapidly cooled, and the temperature of the central region of the sheet glass SG is higher than the temperature of both side portions of the sheet glass SG and in the width direction. To a uniform temperature (plate thickness equalization step: first temperature profile control step). However, when both sides of the sheet glass SG are rapidly cooled, a temperature difference between the temperature of both sides of the sheet glass SG and the temperature of the central region sandwiched between the both sides occurs. If there is a temperature difference, that is, there is a difference in the amount of heat held between both sides and the center region of the sheet glass SG, stress is generated between the both sides and the center region, warping the boundary between both sides and the center region, and distortion. Will occur. For this reason, the 1st temperature profile 20a which suppresses the temperature difference of the temperature of the both sides of the sheet glass SG and the temperature of a center area | region is required. In the first temperature profile 20a, the temperature (average temperature) in the central region of the sheet glass SG and the temperatures on both sides of the sheet glass SG are set to be the first temperature difference X. Here, the temperature difference X is, for example, 30 ° C. to 250 ° C. Not only quenching both sides of the sheet glass SG, but also quenching the central region in the same manner as both sides suppresses warping and distortion occurring at the boundary between the both sides and the central region, and further occurs in the sheet glass SG. The striae can be suppressed. Note that the boundary between both side portions and the central region is a region sandwiched between the both side portions and the central region, and includes a portion to be made uniform in thickness and a portion to be cut after manufacturing.

  Here, the striae occurring in the sheet glass SG will be described. In the space for cooling the sheet glass SG, an upward air flow is generated from the slow cooling furnace 80 along the sheet glass SG. There is a gap, that is, air, between the sheet glass SG and the upper air cooling unit 62 and the lower air cooling units 63a and 63b. The high-temperature sheet glass SG warms the air present in the gap, and the warmed air rises along the sheet glass SG, and thus becomes a rising airflow. The sheet glass SG is cooled by cold (not warmed) air from the bottom to the top, and so-called striae occur at the position of the sheet glass SG corresponding to the position where the ascending airflow is generated. Here, the striae is a kind of distortion in which the thickness (height) of the sheet glass SG fluctuates within a predetermined width, and is continuously generated in a streak shape in the conveying direction of the sheet glass SG. The higher the sheet glass SG is, the larger the amount of cooling that is cooled by the rising air flow, and the more likely the striae are generated. For this reason, the occurrence of striae can be suppressed by reducing the temperature difference between the temperature of the sheet glass SG and the temperature of the air that cools the sheet glass SG. In the present embodiment, in the first temperature profile control step in which the sheet glass SG is the highest temperature, the viscosity of the surface of the sheet glass SG that is easily affected by the rising air current is obtained by quenching the central region and both sides of the sheet glass SG. The time for which is low is shortened. Thereby, the striae which generate | occur | produce in the sheet glass SG by an updraft can be suppressed.

FIGS. 11A and 11B are diagrams illustrating an example of the first temperature profile 20a. In the first temperature profile 20a, the first temperature difference X, which is the difference between the temperature (average temperature) in the central region of the sheet glass SG (sub profile 10a) and the temperature on both sides of the sheet glass SG (sub profile 10d). Is set to be smaller than the temperature difference X1. The first temperature difference X is specifically 30 ° C to 250 ° C, and more preferably 30 ° C to 150 ° C. When only both side portions of the sheet glass SG are rapidly cooled, a difference in the amount of retained heat is generated between the both side portions and the central region of the sheet glass SG, and stress is generated between the both side portions and the central region. For this reason, it is necessary to reduce the difference in the amount of retained heat between the side portions and the central region of the sheet glass SG. FIG. 12 is a diagram illustrating a shape of the sheet glass SG formed by the forming apparatus 40 in plan view. Both side portions G1 in the width direction of the sheet glass SG have a bulbous shape as shown in FIG. This is because the molten glass FG overflows from the pair of top portions 41b and 41b of the molded body 41 and stays on both sides of the sheet glass SG when flowing down along the pair of side surfaces (surfaces) 41c and 41c of the molded body 41. Since it is easy, it becomes such a root-like thick shape. The both side portions G1 have a predetermined thickness with respect to the plate thickness at the center in the width direction of the glass plate G, and a central region (center) having a substantially uniform thickness that can be used as a product (glass substrate) sandwiched between both side portions G1. Part) Since it has a thickness compared with G2, the amount of retained heat is larger than that of the central region G2. When both sides G1 are rapidly cooled, the difference between the amount of retained heat and the central region G2 becomes small. However, when both sides G1 are excessively cooled, the difference in the amount of retained heat with the central region G2 spreads in the opposite direction, causing warpage and the like. Become. For this reason, the difference (temperature difference) in the amount of retained heat between the side portions G1 and the central region G2 does not widen by rapidly cooling the both side portions G1 to reduce the retained heat amount in both side portions G1 and also the central region G2. Thus, warpage, distortion, striae, etc. occurring in the sheet glass SG are suppressed. By setting the first temperature difference X to be 30 ° C. to 250 ° C., the viscosity difference between the viscosity of both side portions G1 and the viscosity of the central region G becomes less than the reference value ^1014.5 , and the sheet glass SG Warpage, distortion, striae, and the like are suppressed.

  In FIG. 11A, the sub-profile 10a in the central region G2 is flat (straight). Thereby, the temperature is uniform in the entire central region G2 having a substantially uniform thickness, and warpage, distortion, and the like in the central region G2 can be suppressed. Further, in FIG. 11B, the sub-profile is formed so that the difference in the amount of heat retained (temperature difference) between the side portions G1 and the central region G2 is eliminated at the boundary between the side portions G1 and the central region G2 where warpage and distortion are likely to occur. 10a and 10d are set to be gentle curves. Thereby, the curvature, distortion, etc. which arise in the boundary of the both sides G1 and the center area | region G2 can be suppressed.

  The second temperature profile 20b and the third temperature profile 20c are lower than the first temperature profile 20a. Moreover, the 2nd temperature profile 20b and the 3rd temperature profile 20c have a temperature gradient in the width direction in the center area | region of the sheet glass SG. Specifically, in the second temperature profile 20b and the third temperature profile 20c, the temperature at the center of the sheet glass SG is high, and the temperatures at both sides of the sheet glass SG are low. More specifically, the second temperature profile 20b and the third temperature profile 20c gradually lower the temperature from the center of the sheet glass SG toward both sides of the sheet glass SG. The central part of the sheet glass SG is the center of the central region. That is, based on the 2nd temperature profile 20b and the 3rd temperature profile 20c, the temperature distribution of the width direction of the sheet glass SG is controlled so that it may become a mountain shape (a parabola which has a convex upward) (warp reduction process) : Second temperature profile control step and third temperature profile control step). That is, the warp reduction step cools the sheet glass SG while maintaining a temperature gradient (a parabola having a convex upward). In other words, the warp reduction step cools the sheet glass SG so that the temperature distribution continuously forms a parabola having a convex upward.

  The control based on the second temperature profile 20b is executed on the upstream side of the second temperature region with respect to the flow direction of the sheet glass SG (second temperature profile control step). The control based on the third temperature profile 20c is executed on the downstream side of the second temperature region with respect to the flow direction of the sheet glass SG (third temperature profile control step). Here, it is preferable that the third temperature profile 20c is set to have a larger gradient than the second temperature profile 20b. Specifically, the second temperature profile 20b is set so that the temperature at the center of the sheet glass SG and the temperature at both sides of the sheet glass SG become the second temperature difference Y1. Further, the third temperature profile 20c is set so that the temperature at the center of the sheet glass SG and the temperature at both sides of the sheet glass SG become the third temperature difference Y2. The third temperature difference Y2 is larger than the second temperature difference Y1. Note that the second temperature difference Y1 is larger than the first temperature difference X. That is, in the temperature profiles 20a to 20c, the temperature difference between the center region and both side portions or the temperature difference between the center portion and both side portions increases along the flow direction of the sheet glass SG (X <Y1 <Y2). .

  Hereinafter, temperature control by each unit will be described in detail.

(3-1) Temperature Control by Upper Air Cooling Unit In the upper air cooling unit 62, as described above, the temperature profile of the region that determines the thickness of the sheet glass SG is realized (first center cooling step). Specifically, the upper air cooling unit 62 makes the temperature distribution in the width direction of the upper cooling adjustment plate 21 uniform. Thereby, the ambient temperature around the surface of the upper cooling adjustment plate 21 (the temperature in the width direction of the sheet glass SG) becomes uniform (sub profile 10a).

(3-2) Temperature Control by Lower Air Cooling Unit In the lower air cooling units 63a and 63b, as described above, the temperature profile of the region where the adjustment of the warp of the sheet glass SG is started is realized (the second central part cooling step and the second cooling step). 3 central part cooling process). Specifically, the lower air cooling units 63a and 63b adjust the temperature distribution of the lower cooling adjustment plate 31 so that the temperature in the width direction of the sheet glass SG becomes a mountain shape (a parabola having a convex upward). Specifically, the temperature at the center in the longitudinal direction of the lower cooling adjustment plate 31 is set to the highest temperature. Moreover, the temperature of the longitudinal direction both ends of the lower cooling adjustment plate 31 is set to the lowest temperature. Further, the temperature is controlled to gradually decrease from the center toward both ends. More specifically, the temperature of the gas blown out from the central adjustment part 33c among the first side adjustment part 33a, the second side adjustment part 33b, and the central part adjustment part 33c included in the temperature adjustment pipe 33 is set. The temperature of the gas blown out from the first side adjustment unit 33a and the second side adjustment unit 33b is increased. As a result, the ambient temperature around the surface of the lower cooling adjustment plate 31 (the temperature in the width direction of the sheet glass SG) becomes a mountain shape (sub profile 10b, sub profile 10c).

  In the present embodiment, two lower air cooling units 63a and 63b are arranged along the flow direction of the sheet glass SG. The lower air cooling unit 63b disposed below the sheet glass SG in the flow direction is controlled so as to form a larger parabolic temperature distribution than the lower air cooling unit 63a disposed above. Specifically, as described above, the lower air cooling unit 63b realizes the temperature gradient of the profile 10b (temperature gradient between the center and both sides) (see Y1 in FIG. 10) realized by the lower air cooling unit 63a. The temperature gradient of the temperature profile 10c (see Y2 in FIG. 10) is increased (Y1 <Y2).

(3-3) Temperature Control by Cooling Roll As described above, the cooling roller 51 realizes a temperature profile in a region that affects the uniformity of the thickness of the sheet glass SG (rapid cooling process). The cooling roller 51 rapidly cools both side portions of the glass joined at the lower end portion 41 a of the molded body 41. That is, the ambient temperature around the side portion and the side portion of the sheet glass SG is lower than the ambient temperature around the center portion of the sheet glass SG (sub profile 10d).

(3-4) Temperature Control by Upper Water Cooling Unit In the upper water cooling unit 72, as described above, the temperature profile of the region that affects the adjustment of the thickness and / or warpage amount of the sheet glass SG is realized (first side portion). Cooling step). The upper water cooling unit 72 generates a temperature lower than the temperatures generated by the upper air cooling unit 62 and the lower air cooling unit 63a. That is, the ambient temperature around the side portion and the side portion of the sheet glass SG is lower than the ambient temperature around the central region of the sheet glass SG (sub profile 10e).

(3-5) Temperature Control by Lower Water Cooling Unit As described above, the lower water cooling unit 73 realizes the temperature profile of the region that affects the adjustment of the warp amount of the sheet glass SG (second side cooling step). The lower water cooling unit 73 generates a temperature lower than the temperature generated by the lower air cooling units 63a and 63b. That is, the ambient temperature around the side portion and the side portion of the sheet glass SG is lower than the ambient temperature around the central region of the sheet glass SG (sub profile 10f).

(4) Features (4-1)
In the method for manufacturing a glass substrate according to the present embodiment, the glass substrate is manufactured by overflowing the molten glass from the molded body and forming it into a sheet glass by a downdraw method, and cooling the sheet glass while stretching it in the flow-down direction. . At this time, when the sheet glass is in the temperature range from the temperature higher than the softening point to the vicinity of the annealing point after the sheet glass is separated from the molded body, the tension is directed toward the side in the width direction of the sheet glass. Is added, and the viscosity difference between the viscosity of the side portion and the viscosity of the central region sandwiched between the side portions is cooled so as to be equal to or less than the reference value. As a result, the difference in the amount of heat retained between the both side portions and the central region of the sheet glass is reduced, the stress generated between the both side portions and the central region is reduced, and the boundary between the both side portions and the central region is generated. Distortion and warpage can be reduced.
Moreover, in the manufacturing method of the glass substrate which concerns on embodiment, in the 1st temperature range from just below a molded object to the annealing point, the temperature of the both sides of the width direction of the sheet glass SG is the flow-down direction of the sheet glass SG. It is controlled according to the position. Specifically, a plurality of temperature profiles are set along the flow direction of the sheet glass SG, and a plurality of water cooling units 72 and 73 arranged along the flow direction of the sheet glass SG based on the plurality of temperature profiles. Thus, the temperature of the side portion of the sheet glass SG is controlled.

  Moreover, in the manufacturing method of the glass substrate which concerns on the said embodiment, the cooling rollers 51 and 51 quench the side part of the sheet glass SG above the water cooling units 72 and 73. FIG. Since the thickness of the side portion of the sheet glass SG cooled by the cooling rollers 51 and 51 increases, the side portion of the sheet glass SG has a larger amount of heat than the central portion of the sheet glass SG. Therefore, the temperature control of the side portion of the sheet glass SG greatly affects the temperature control of the central portion of the sheet glass SG.

  By the way, with the recent increase in demand for glass substrates, mass production of glass substrates has become necessary. Therefore, it has become difficult to spend the same time as before in the process of cooling the sheet glass SG. However, if the cooling rate of the glass sheet SG is simply increased, a glass substrate with good quality cannot be manufactured.

  In the manufacturing method of the glass substrate which concerns on the said embodiment, the temperature of the side part of the sheet glass SG is implement | achieved by controlling independently the several cooling unit arrange | positioned along the flow-down direction of the sheet glass SG. Thereby, since the side part of the sheet glass SG can be cooled effectively, even if it is a case where cooling time is made into a short time, a quality glass substrate can be manufactured.

(4-2)
Moreover, in the said embodiment, after rapidly cooling the ear | edge part which is the both sides of the sheet glass SG using the cooling roller 51, the ear | edge part of the sheet glass SG is continuously cooled by the side part cooling unit 71. FIG.

  When the ears of the sheet glass SG are rapidly cooled by the cooling roller 51, a tension is applied in the width direction of the sheet glass SG as disclosed in JP-A-10-291826. However, even after the sheet glass SG formed immediately below the molded body 41 is rapidly cooled by the cooling roller 51, the width direction shrinkage (shrinkage) easily occurs. In the above embodiment, following the cooling by the cooling roller 51, the ear portion of the sheet glass SG is continuously cooled by the side cooling unit 71. Thereby, the shrinkage | contraction of the width direction of the sheet glass SG can be suppressed.

  Furthermore, in the above embodiment, the cooling capacity of the side cooling unit 71 is made lower than the cooling capacity of the cooling roller 51. Thereby, the crack of the sheet glass SG can be prevented.

(4-3)
Moreover, in the manufacturing method of the glass substrate which concerns on the said embodiment, after quenching the sheet glass SG by heat conduction, the sheet glass SG is cooled by radiant heat transfer. Thereby, the ear | edge part of the sheet glass SG can be cooled efficiently.

(4-4)
Furthermore, in the glass substrate manufacturing method according to the above-described embodiment, members (upper support member 731a and lower support member 731b) on which a fiberboard can be arranged are provided on the surface of the lower water cooling plate 731. Thereby, about the area | region cooled with the lower water cooling plate 731, according to the in-furnace environment at the time of cooling, heat radiation can be partially interrupted | blocked.

(4-5)
In the above embodiment, the upper water cooling unit 72 is configured to be horizontally movable on the top plate 735 of the lower water cooling unit 73. Further, the lower water cooling unit 73 is configured to be able to support the blocking member.

  The upper water cooling unit 72 can control the temperature of the sheet glass SG by changing the temperature and / or flow rate of the fluid sent to the upper water cooling plate 721 and by approaching or moving away from the sheet glass SG. On the other hand, the lower water cooling unit 73 changes the temperature and / or flow rate of the fluid fed into the lower water cooling plate 731, supports the blocking member on the upper support member 731 a and the lower support member 731 b, By removing the blocking member from the support member 731b or changing the area of the blocking member to be supported, the cooling capacity can be changed and the temperature of the sheet glass SG can be controlled.

(4-6)
In the above embodiment, while maintaining the viscosity of the side portion of the sheet glass SG away from the molded body ¹⁰ from 9.0 ^{to 10} 14.5 within the Poise, the step of cooling is performed sheet glass SG. If the viscosity of the side portion of the sheet glass SG is less than ¹⁰ 9.0 Poise, since the sheet glass SG is easily deformed, shrinkage in the width direction of the sheet glass SG prone. Moreover, when the viscosity of the side part of the sheet glass SG exceeds 10 ^14.5 Poise, it cannot endure the stress which generate | occur | produces inside the sheet glass SG, and the sheet glass SG may be broken.

That is, while maintaining the viscosity of the side part of the sheet glass SG away from the molded body within the range of 10 ^9.0 to 10 ^14.5 Poise, the sheet glass SG is prevented from cracking while being cooled. Shrinkage in the width direction can be suppressed. Thereby, it will be in the state where tension is applied to the width direction of sheet glass SG toward the both sides of sheet glass SG. Moreover, the side part of sheet glass SG is cooled in steps or continuously by cooling so that the viscosity of the side part of sheet glass SG may become high along a flow-down direction. Thereby, the sheet glass SG is prevented from being excessively cooled and cracked at a time.

(4-7)
In the above embodiment, the sheet glass SG having a viscosity of 10 ^5.7 to 10 ^7.5 Poise just below the molded body is set so that the viscosity of the side portion is in the range of 10 ^9.0 to 10 ^10.5 Poise. While rapidly cooling and cooling the sheet glass SG, by further cooling the sheet glass SG so that the viscosity of the side portion is in the range of 10 ^10.5 to 10 ^14.5 Poise, while preventing the sheet glass SG from cracking The shrinkage in the width direction of the sheet glass SG is suppressed. The viscosity of the central region is rapidly cooled so that ¹⁰ 5.7 ^{to 10} 7.5 in the range of Poise, after quenching of the sheet glass SG, the viscosity of the central region of ¹⁰ 7.5 ^{to 10} 9.67 Poise By further cooling so as to be within the range, the stress generated between the side portion and the central region can be suppressed, and the sheet glass SG can be prevented from cracking.

  In this way, by bringing the cooling roller 51 into contact with the sheet glass SG, heat can be taken from the sheet glass SG in a short time due to heat conduction, and thus the sheet glass SG can be rapidly cooled. Further, by holding the sheet glass SG by the cooling roller 51, shrinkage in the width direction can be more effectively suppressed.

  Further, since the sheet glass SG rapidly cooled by the cooling roller 51 is continuously cooled by the radiant heat transfer by the cooling unit 60 installed separately from the sheet glass SG, the surface of the sheet glass SG is excessively cooled. Breaking can be prevented. In addition, by providing the some cooling unit 60, it is suppressed effectively that the surface of the sheet glass SG is cooled excessively, and the crack of the sheet glass SG can be suppressed effectively.

(4-8)
In the said embodiment, in a plate | board thickness equalization process, the temperature distribution of the width direction in the center area | region of the sheet glass SG is made uniform, and the temperature of the both sides of the sheet glass SG is made lower than the temperature of a center area | region. Thereby, the side part of the sheet glass SG is cooled so that contraction in the width direction is suppressed, and the central region of the sheet glass SG is cooled so that the plate thickness is uniform. It can be made uniform in the width direction.

  In addition, plate thickness can be made more uniform by performing plate thickness equalization processing from immediately after the sheet glass SG is separated from the molded body until the temperature of the sheet glass SG is cooled to the softening point.

  In the above-described embodiment, in the warp reduction process, the temperature distribution in the width direction of the sheet glass SG is lowered as compared with the plate thickness equalizing process, and the width from the center in the width direction of the central region of the sheet glass SG is directed to the side. Thus, a temperature gradient is formed in the width direction of the sheet glass SG. And it cools so that the temperature gradient of the sheet glass SG reduces as the temperature of the sheet glass SG goes to a strain point. Thereby, it can cool so that a tensile stress may always work in the center part of the width direction of the sheet glass SG. Moreover, it can cool, maintaining the plate | board thickness of the sheet glass SG uniformly, and the curvature of the sheet glass SG can be reduced.

  In the warp reduction step, the sheet glass SG is cooled toward the vicinity of the strain point of the sheet glass SG so that the temperature gradient formed in the width direction of the sheet glass SG is reduced. By cooling the sheet glass SG to the strain point so as to reduce the temperature gradient, the cooling amount at the center in the width direction of the sheet glass SG becomes larger than the cooling amount at both sides in the width direction of the sheet glass SG. . Thereby, since the volumetric shrinkage rate of the sheet glass SG increases from the both sides in the width direction toward the center, tensile stress acts on the center of the sheet glass SG. In particular, a tensile stress acts on the center part of the sheet glass SG in the flow direction and the width direction of the sheet glass SG. In addition, it is preferable that the tensile stress acting in the flow direction of the sheet glass SG is larger than the tensile stress acting in the width direction of the sheet glass SG. Since it can cool, maintaining the flatness of the sheet glass SG by tensile stress, the curvature of the sheet glass SG and by extension, a glass plate can be reduced more.

(5) Modification (5-1) Modification A
In the said embodiment, the temperature adjustment pipe 33 is divided into three internally, and the temperature adjustment pipe 33 has the 1st side part adjustment part 33a, the 2nd side part adjustment part 33b, and the center part adjustment part 33c. The temperature adjustment pipe 33 is not limited to three divisions, and may be divided into five divisions. Thereby, finer temperature control can be independently performed in the width direction of the sheet glass SG.

(5-2) Modification B
In the above embodiment, pure nickel is used as the material having high thermal conductivity, but other materials may be used as the material having high thermal conductivity. For example, molybdenum, sintered SiC, recrystallized SiC, artificial graphite, iron, tungsten, or the like may be used. However, when molybdenum is employed, it is preferably used in a non-oxidizing atmosphere. When molybdenum is used in an oxidizing atmosphere, it is preferable to apply an oxidation resistant coating. Sintered SiC and recrystallized SiC can be employed in an oxidizing atmosphere, and artificial graphite, iron, and tungsten can be employed when used in a non-oxidizing atmosphere.

(5-3) Modification C
In the above embodiment, channels (grooved steel shape) are used as the upper cooling adjustment plate 21 and the lower cooling adjustment plate 31, but the upper cooling adjustment plate 21 and the lower cooling adjustment plate 31 are not limited to the above shapes, and other It may be a shape. At this time, it is possible to minimize the contact between the adjacent upper cooling adjustment plate 21 and the lower cooling adjustment plate 31 and suppress the heat conduction between the adjacent upper cooling adjustment plate 21 and the lower cooling adjustment plate 31. preferable. For example, the upper cooling adjustment plate 21 and the lower cooling adjustment plate 31 may have a round bar (column) shape, an odd-numbered polygonal column shape, or the like.

(5-4) Modification D
In the said embodiment, it controlled so that atmospheric temperature became uniform along the width direction of the sheet glass SG by the upper air cooling unit 62 (plate thickness equalization process). Thereby, in the said embodiment, the thickness (thickness) of the sheet glass SG was made uniform. However, the upper air cooling unit 62 may be configured such that the temperature can be changed along the width direction of the sheet glass SG. For example, the space formed inside the air cooling unit 62 is divided into a plurality of spaces so that each space can be cooled, or a structure in which a heat insulating material can be partially installed inside the air cooling unit 62 is provided. You may enable it to change the atmospheric temperature of a direction. Thereby, even when the temperature in the central region is made uniform, even if the thickness in the width direction of the sheet glass SG cannot be realized due to some influence, the thickness of the sheet glass SG is uniform. Can be achieved.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

(Examples and comparative examples)
In the first temperature profile 20a, the viscosity of the central region G2 of the sheet glass SG (viscosity set by the sub-profile 10a) and the viscosity of both side portions G1 of the sheet glass SG (viscosity set by the sub-profile 10d). The temperature profile was changed so that the difference changed, and the maximum strain (retardation value) generated at the boundary between the central region G2 and both side portions G1 and the viscosity of the central region G2 and both side portions G1 were measured. The measured results are shown in Table 1. The second and third temperature profiles were the same.

As shown in Examples 1-3 of Table 1, both side portions G1, each of the viscosity of the center region ^G2, 10 ^9.0 to 10 14.5 within the ^Poise, 10 ^{5.7 ~10} 9.67 Poise The maximum strain could be reduced to 1.9 nm or less by reducing the difference in viscosity between the both side portions G1 and the central region G2 while maintaining the viscosity so as to be in the above range. Further, as shown in Examples 4 and 5 in Table 1, by maintaining the respective viscosities of the both side portions G1 and the central region G2 within the above-described ranges, the viscosity difference becomes 10 ^14.5 (≈10 ^14.5 − 10 ^9.67 ) Even when there was about Poise, the maximum strain could be 2.3 nm or less. On the other hand, as shown in Comparative Examples 1 and 2 in Table 1, when the viscosities of the both side portions G1 and the central region G2 deviate from the above range, even if the viscosity difference is less than 10 ^14.5 , the maximum strain is 9. It became 1 nm-9.2 nm, and became large compared with Examples 1-5. Further, as shown in Comparative Example 3 in Table 1, when the viscosity of the both side portions G1 and the central region G2 is out of the above range and the difference in viscosity is 10 ^14.5 or more, the maximum strain is 26.5 nm. Compared to 1 and 2, it became larger.

From the above, at a first temperature profile region, both side portions G1, each of the viscosity of the center region ^G2, 10 ^9.0 to 10 14.5 within the ^Poise, 10 ^{5.7 ~10} 9.67 Poise It was found that the strain generated at the boundary between the central region G2 and the both side portions G1 can be reduced by reducing the difference in viscosity between the both side portions G1 and the central region G2 while maintaining the viscosity so as to be in the above range.

DESCRIPTION OF SYMBOLS 11 Dissolving device 12 Clarification device 21 Upper cooling adjustment plate 22 Back water cooling unit 31 Lower cooling adjustment plate 32 Temperature control unit 40 Molding device 41 Molding body 41a Molding body lower end 41b Molding body top 41c Molding body side surface (surface)
43 Groove 50 Partition member 51 Cooling roller 60 Cooling unit 61 Central cooling unit 62 Upper air cooling units 63a and 63b Lower air cooling unit 71 Side cooling unit 72 Upper water cooling unit 73 Lower water cooling unit 80 Slow cooling furnace 81 Pulling down roller FG Molten glass SG Sheet glass 100 Glass Substrate Manufacturing Device 721 Upper Water Cooling Plate 722 Upper Connection Unit 731 Lower Water Cooling Plate 732 Lower Connection Unit

Claims (6)

By a downdraw method, a molten glass is overflowed from a molded body and formed into a sheet glass, which is a glass substrate manufacturing method for manufacturing a glass substrate by cooling while stretching the sheet glass in a flow-down direction,
When the sheet glass is in the temperature range from the temperature higher than the softening point to the vicinity of the annealing point after the sheet glass is separated from the molded body, the side including the edges on both sides in the width direction of the sheet glass parts and, in the thin central region thickness than the side sandwiched by the side, pressure to give a tension toward the side, suppressing so the stress generated in the boundary between the side and the central region To cool the sheet glass,
In cooling the sheet glass,
It said side cooled so that the viscosity of said side becomes ¹⁰ 9.0 ^~10 14.5 Poise,
After cooling the side portion, the side portion is further cooled while maintaining the viscosity of the side portion within a first range of 10 ^9.0 to 10 ^14.5 Poise, and the viscosity of the central region is 10 ^5.7 to 10 ^9.67 cool in the second range of Poise,
A method for producing a glass substrate, comprising: Cooling so that the viscosity of the side portion and the viscosity of the central region become higher along the flow-down direction,
The method for producing a glass substrate according to claim 1 . In the temperature region,
In order to make the thickness of the sheet glass uniform in the width direction, the temperature distribution in the width direction in the central region of the sheet glass is made uniform, and the temperature of both side portions of the sheet glass is set to the temperature of the central region. A lower plate thickness equalizing step,
After the plate thickness homogenizing step, in order to reduce the warp of the sheet glass, the temperature distribution in the width direction of the sheet glass from the thickness homogenizing step to a low temperature, the side from the center of the central region A warp reduction step of forming a temperature gradient in the width direction of the sheet glass toward
The method for producing a glass substrate according to claim 1 or 2 , wherein: The viscosity of the sheet glass directly under the molded body is 10 ^5.7 to 10 ^7.5 Poise,
The viscosity of the side of the sheet glass is rapidly cooled the sheet glass so that the above ¹⁰ 9.0 Poise,
The viscosity of the central region of the sheet glass is rapidly cooled the sheet glass so that the above ¹⁰ 5.7 Poise,
The manufacturing method of the glass substrate of any one of Claim 1 to 3 characterized by the above-mentioned.   The said side part is a manufacturing method of the glass substrate of any one of Claims 1-4 located in the range within 200 mm from the edge of the width direction of the said sheet glass. A pair of top portions, a lower end portion, and a pair of surfaces extending from the pair of top portions to the lower end portion, after overflowing the molten glass from the pair of top portions, flow down along the pair of surfaces, A molded body that forms a sheet glass by joining at the lower end, and
When the sheet glass separated from the molded body is in a temperature region higher than the softening point , the side portion including the edges on both sides in the width direction of the sheet glass, and the thickness of the side portion sandwiched between the side portions of the thin central region, a first thermal processing unit for the viscosity of the side line heat treatment of the side to ¹⁰ 9.0 ^{to 10} 14.5 Poise,
When the sheet glass is in a temperature region from the vicinity of the softening point to the vicinity of the annealing point, the side portion, and a second heat treatment unit for performing heat treatment of the central region ,
The second heat treatment unit applies tension toward the side portion, cools the sheet glass so as to suppress stress generated at a boundary between the side portion and the central region, and in cooling the sheet glass, the viscosity of the side to cool and maintained at ¹⁰ from 9.0 ^{to 10} 14.5 within the Poise, cooling the viscosity of the central area in the range of ¹⁰ 5.7 ^{to 10} 9.67 Poise,
An apparatus for producing a glass substrate.

Images