JP2019116415A - Method and apparatus for manufacturing glass substrate - Google Patents

Abstract

To prevent scratches from occurring in regions on both sides of a glass plate in a width direction when conveying the glass plate.SOLUTION: A method for manufacturing a glass substrate comprises: a molding step of molding molten glass using an overflow down draw method to form a glass plate; and the conveyance step of conveying the glass plate downward while holding the regions on both sides of the glass plate in a width direction by at least a pair of conveyance rollers. In the molding step, an inclined region having a thickness of the glass plate inclined in the width direction is formed in the regions on both sides so as to increase the thickness of the glass plate toward the outside in the width direction. In the conveyance step, a position having the glass plate held by the conveyance roller is controlled within a region where a thickness inclination of a portion of the glass plate facing the conveyance rollers is smaller than an acceptable value, in the inclined region.SELECTED DRAWING: Figure 6

Description

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

  There is known a method of producing a sheet glass (glass plate) using a downdraw method. The sheet glass formed by the downdraw method has a central region in the width direction having a substantially constant thickness, and an end portion (ear portion) located on the width direction outer side of the central region and thicker than the central region. Have. The central region has a product area that is a product of the glass substrate. In the downdraw method, in order to stably convey the formed sheet glass downward, the boundary region between the central region and the end of the sheet glass is nipped by the conveyance roller and conveyed downward (patented) Literature 1).

JP, 2013-212987, A

  Since the thickness of the edge of the sheet glass is thicker than the thickness of the central region, the thickness of the boundary region gradually increases from the side of the central region toward the side of the edge, depending on the position in the width direction The thickness of the sheet glass is different. For this reason, when the boundary region is pinched by the transport roller, the contact area between the sheet glass and the transport roller becomes small, and the pressure that the sheet glass receives from the transport roller tends to be uneven. When the sheet is pinched at a high pressure locally by the transport roller, the sheet glass may be scratched, and when cutting in a later step, the scratch may become a starting point and the sheet glass may be broken.

  Therefore, the present invention provides a method of manufacturing a glass substrate and an apparatus for manufacturing a glass substrate, which can suppress generation of a scratch in regions on both sides in the width direction of the glass plate when transporting the glass plate. To aim.

One aspect of the present invention is a method for producing a glass substrate,
Forming the molten glass using an overflow down draw method to form a glass plate;
And conveying the glass sheet downward while holding the regions on both sides in the width direction of the glass sheet between at least a pair of conveyance rollers,
In the forming step, an inclined area is formed in the area on both sides so that the thickness of the glass plate becomes thicker toward the width direction outer side,
In the transport step, the position at which the transport roller sandwiches the glass sheet is adjusted within the slope area to an area in which the slope of the thickness of the glass sheet facing the transport roller is smaller than the allowable value. Are characterized.

In the forming step, before sandwiching the glass plate by the transport roller, the regions on both sides of the glass plate are pinched by a cooling roller disposed upstream of the transport roller in the transport direction,
It is preferable that the position at which the transport roller sandwiches the glass plate is adjusted to a position at a predetermined interval or more inside in the width direction from the position of the glass plate sandwiched by the cooling roller.

And a control step of adjusting a position at which the transport roller clamps the glass plate,
In the control step, the position at which the transport roller sandwiches the glass plate is adjusted within the tilt area into an area in which the inclination of the thickness of the glass sheet facing the transport roller is smaller than the allowable value. Is preferred.

Furthermore, the method further comprises a measuring step of measuring the inclination of the thickness of the glass sheet in the inclined area,
In the control step, it is preferable to adjust the position at which the transport roller sandwiches the glass sheet, based on the thickness of the central region in the width direction of the glass sheet and the measurement result of the inclination of the thickness.

  In the control step, it is preferable to adjust the position at which the transport roller sandwiches the glass plate in a region where the inclination of the thickness is further reduced.

  It is preferable that the position at which the transport roller sandwiches the glass plate is adjusted to a position at which a predetermined interval or more is opened inward in the width direction from both ends in the width direction of the glass plate.

  It is preferable that the position at which the transport roller sandwiches the glass plate is adjusted in an area in which the thickness of the portion of the glass plate facing the transport roller is equal to or less than the allowable thickness.

In the conveying step, the glass plate is conveyed downward while the regions on both sides are held by a plurality of conveying rollers arranged at intervals in the conveying direction.
The allowable value is preferably set to a smaller value as the transport roller is positioned more downstream in the transport direction.

Another aspect of the present invention is a glass substrate manufacturing apparatus,
A forming apparatus for forming molten glass by an overflow down draw method to form a glass sheet;
A conveyance device configured to convey the glass sheet downward while sandwiching the regions on both sides in the width direction of the glass sheet by at least a pair of conveyance rollers;
The forming apparatus forms, in the regions on both sides, an inclined region which is inclined so that the thickness of the glass plate is thickened outward in the width direction,
The position at which the transport roller sandwiches the glass plate is adjusted within a range in which the slope of the thickness of the glass plate facing the transport roller is smaller than the allowable value in the slope region. It features.

  ADVANTAGE OF THE INVENTION According to this invention, when conveying a glass plate, a glass plate can be conveyed, suppressing that the area | region of the both sides of the width direction of a glass plate generate | occur | produces a damage | wound.

It is a flowchart of the manufacturing method of the glass plate which concerns on this embodiment. It is a schematic diagram which shows the manufacturing apparatus of the glass plate used by the manufacturing method of a glass plate. It is a schematic diagram (cross section) of an outline of a molding device. It is a schematic diagram (side view) of the outline of a forming device. It is a control block diagram of a control device. It is a figure explaining the pinching position of a conveyance roller. It is a figure which shows the relationship between the thickness of a center area | region, and the thickness of the glass plate in a clamping position.

  In the method of manufacturing a glass substrate according to the present embodiment, for example, a glass substrate for a TFT display is manufactured. Glass sheets are manufactured using an overflow downdraw method. Hereinafter, the manufacturing method of the glass substrate concerning this embodiment is explained, referring to drawings.

(1) Outline of Method of Manufacturing Glass Substrate First, with reference to FIG. 1 and FIG. 2, a plurality of processes included in the method of manufacturing a glass substrate and a glass substrate manufacturing apparatus 100 used in the plurality of processes will be described. As shown in FIG. 1, the method for producing a glass substrate mainly includes a melting step S1, a clarifying step S2, a forming step S3, a cooling step S4, and a cutting step S5. In addition to this, the method of manufacturing a glass substrate includes a grinding process, a polishing process, a cleaning process, an inspection process, a packing process, and the like, and a plurality of glass substrates stacked in the packing process are transported to a supplier. .

Melting process S1 is a process in which the raw material of glass is melted. The glass raw material is formulated to have a desired composition, and then introduced into the melting device 11 disposed upstream, as shown in FIG. The glass material comprises, for example, a composition of SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , CaO, SrO, BaO or the like. Specifically, a glass material having a strain point of 660 ° C. or higher is used. The raw material of the glass is melted by the melting device 11 to become the molten glass FG (see FIGS. 3 and 4). The melting temperature is adjusted according to the type of glass. In the present embodiment, the glass material is melted at 1500 ° C to 1650 ° C. The molten glass FG is sent to the refining device 12 through the upstream pipe 23.

  The fining step S2 is a step of removing air bubbles in the molten glass FG. The molten glass FG from which bubbles have been removed in the fining 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 formed body 41 after being continuously supplied to the formed body 41 (see FIGS. 3 and 4) included in the forming apparatus 40. The overflowed molten glass FG flows down along the surface of the formed body 41. Thereafter, the molten glass FG is joined at the lower end portion 41a (see FIGS. 3 and 4) of the formed body 41 and formed into a sheet glass SG. The sheet glass SG has a side (also referred to as an ear or an end) SP (see FIG. 6) located at an end in the width direction and a central area CA in the width direction (see FIG. 6) sandwiched between the sides. Have. The thickness of the side portion of the sheet glass SG is formed thicker than the thickness of the central region. In the forming step S3, in the regions R and L on both sides in the width direction of the sheet glass SG (see FIG. 4), inclined regions (boundary regions) SA inclined such that the thickness of the sheet glass SG becomes thicker toward the width direction outer side (See FIG. 6) is formed. That is, the sheet glass SG further has an inclined region between the central region and the side (the region serving as the boundary). The slope means that the thickness of the sheet glass SG changes in the width direction of the sheet glass SG, that is, it has a slope, and the sloped area indicates the thickness of the sheet glass SG It means a region inclined in the width direction. The central region of the sheet glass SG is a region which becomes a product of the glass substrate, having a constant thickness. The thickness of the central region of the sheet glass SG is, for example, a thin plate of 0.7 mm or less, preferably 0.4 mm or less. The width direction of the sheet glass SG is a direction orthogonal to the direction in which the sheet glass SG flows down (also referred to as the flow direction or the transport direction) and the thickness direction of the sheet glass SG.

  In the cooling step S4, the sheet glass SG is conveyed downward while the regions on both sides in the width direction of the sheet glass SG are sandwiched by a pulling-down roller (conveyance roller) described later provided in the conveyance direction of the sheet glass SG. Cooling (slow cooling). That is, in the cooling step S4, a conveyance step of conveying the sheet glass SG downward while conveying the sheet glass SG downward is performed. The transport process will be described in detail later. The sheet glass SG is cooled to a temperature close to room temperature through the cooling step S4. The thickness (plate thickness) of the glass substrate, the amount of warpage of the glass substrate, and the amount of distortion of the glass substrate are determined in accordance with the state of cooling 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 the cutting step S5, specifically, the sheet glass SG after slow cooling is cut to separate the end portion and the boundary area from the central area, and the central area of the sheet glass SG is cut to a predetermined length, thereby the glass substrate Get The cut glass substrate is further cut into a predetermined size to produce a glass substrate of a target size.

  Next, with reference to FIGS. 3 to 5, the configuration of the forming apparatus 40 included in the glass substrate manufacturing apparatus 100 will be described.

(2) Configuration of Forming Apparatus FIGS. 3 and 4 show a schematic configuration of the forming apparatus 40. FIG. FIG. 3 is a cross-sectional view of the forming apparatus 40. As shown in FIG. FIG. 4 is a side view of the forming apparatus 40. FIG.

  The forming apparatus 40 has a passage through which the sheet glass SG passes, and a space surrounding the passage. A space surrounding the passage is composed of an overflow chamber 20, a forming chamber 30, and a cooling chamber 80.

  The overflow chamber 20 is a space for forming the molten glass FG sent from the fining device 12 into the sheet glass SG. The molten glass FG flows down along the surface of the formed body 41, joins at the lower end portion 41a of the formed body 41, and is formed into a sheet glass SG.

  The forming chamber 30 is disposed below the overflow chamber 20 and is a space for adjusting the thickness and the amount of warpage of the sheet glass SG. In the forming chamber 30, a part of the cooling step ST4 is performed. The temperature of the sheet glass SG is gradually lowered downstream of the lower end portion 41 a of the molded body 41.

  The cooling chamber 80 is disposed below the overflow chamber 20 and is a space for adjusting the amount of strain of the sheet glass SG. Specifically, in the cooling chamber 80, the sheet glass SG which has passed through the inside of the forming chamber 30 is cooled to a temperature near room temperature through the annealing point and the strain point. In addition, the inside of the cooling chamber 80 is divided into a plurality of spaces by a plurality of heat insulating members 80 b arranged at intervals in the transport direction of the sheet glass SG.

  The molding apparatus 40 mainly includes a molded body 41, a partition member 50, a cooling roller 51, a cooling unit 60, pulling rollers 81a to 81g, heaters 82a to 82g, and a cutting device 90. ing. Furthermore, the molding device 40 includes a control device 500 (see FIG. 5). The control device 500 controls the drive unit of each configuration included in the molding device 40.

  Hereinafter, each component included in the molding apparatus 40 will be described in detail.

(2-1) Molded Body The molded body 41 is provided in the overflow chamber 20. The formed body 41 forms the molten glass FG into the sheet glass SG by overflowing the molten glass FG.

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

  In addition, the molded body 41 has an inlet 42 (see FIG. 4) at a first end in the longitudinal direction (left and right direction in FIG. 4). The inflow port 42 is connected to the above-described downstream pipe 24, and the molten glass FG that has flowed out of the fining device 12 is poured into the formed body 41 from the inflow port 42. Grooves 43 are 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 a second end opposite to the first end in the width direction of the sheet glass SG. The groove 43 is formed deepest in the vicinity of the inflow port 42 and gradually shallows closer to the second end. The molten glass FG poured into the formed body 41 overflows from the pair of top portions 41 b and 41 b of the formed body 41 and flows down along the pair of side surfaces (surfaces) 41 c and 41 c of the formed body 41. Thereafter, the molten glass FG merges at the lower end portion 41 a of the formed body 41 to form a sheet glass SG.

At this time, the liquidus temperature of the sheet glass SG at the lower end portion 41a of the formed body 41 is 1100 ° C. or more, the liquidus viscosity is 2.5 × 10 ⁵ poise or more, and more preferably, the liquidus temperature is 1160 The liquid phase viscosity is 1.2 × 10 ⁵ poise or more. Moreover, the viscosity of the side part (ear part, edge part) of the sheet glass SG in the lower end part 41a of the molded object 41 is less than 10 ^5.7 Poise.

(2-2) Partition Member The partition member 50 is a member that blocks the transfer of heat from the overflow chamber 20 to the forming chamber 30. The partition member 50 is disposed in the vicinity of the joining point of the molten glass FG. Moreover, as shown in FIG. 3, the partition member 50 is arrange | positioned at the thickness direction both sides of molten glass FG (sheet glass SG) which joined in the confluence | merging point. The partition member 50 is a heat insulating material. The partition member 50 blocks the transfer of heat from the upper side to the lower side of the partition member 50 by partitioning the upper atmosphere and the lower atmosphere of the joining point of the molten glass FG.

(2-3) Cooling Roller The cooling roller 51 is provided in the forming chamber 30. More specifically, the cooling roller 51 is disposed immediately below the partition member 50. The cooling rollers 51 are disposed on both sides in the thickness direction of the sheet glass SG and on both sides in the width direction of the sheet glass SG. The cooling rollers 51 disposed on both sides in the thickness direction of the sheet glass SG operate in pairs. That is, the regions R, L on both sides in the width direction of the sheet glass SG are sandwiched by the two pairs of cooling rollers 51, 51,.

The cooling roller 51 is air-cooled by a gas such as air passing through an air-cooled pipe passed through the inside. The cooling roller 51 is in contact with the side (ear, end) of the sheet glass SG, and quenches the region on both sides including the side (ear, end) of the sheet glass SG by heat conduction (quenching step) . The viscosity of the side portion of the sheet glass SG in contact with the cooling roller 51 is a predetermined value (specifically, 10 ^9.0 poise) or more.

  The cooling roller 51 is rotationally driven by a cooling roller drive motor 390 (see FIG. 5). The cooling roller 51 also functions to cool the regions R and L on both sides of the sheet glass SG and to pull the sheet glass SG downward.

(2-4) Cooling Unit The cooling unit 60 is provided in the overflow chamber 20 and the forming chamber 30, and is a unit for cooling the sheet glass SG to near the annealing point. The cooling unit 60 has a plurality of cooling elements 61-65. In FIG. 4, the cooling unit 60 is shown only in the forming chamber 30. The plurality of cooling elements 61 to 65 are arranged along the width direction of the sheet glass SG and the flow direction of the sheet glass SG. Specifically, the plurality of cooling elements 61-65 include central area cooling elements 61-63 and side cooling elements 64, 65.
The central area cooling elements 61 to 63 are air cooled to cool the central area CA of the sheet glass SG. Here, the central region of the sheet glass SG is a central portion in the width direction of the sheet glass SG, and is a region including the effective width of the sheet glass SG and the vicinity thereof. In other words, the central area of the sheet glass SG is an area located between the areas R and L on both sides of the sheet glass SG. The central area cooling elements 61 to 63 are arranged along the flow direction so as to face the surface of the central area CA of the sheet glass SG. Each unit included in central region cooling elements 61-63 is independently controllable.
Also, the side cooling elements 64, 65 are water cooled to cool the regions R, L on both sides of the sheet glass SG. The side cooling elements 64 and 65 are disposed along the flow direction at positions opposite to the surfaces of the regions R and L on both sides of the sheet glass SG. Each unit contained in the side cooling elements 64, 65 is independently controllable.

(2-5) Pull-down roller (conveying roller)
The pulling rollers 81a to 81g are provided in the cooling chamber 80, pull the sheet glass SG having passed through the inside of the forming chamber 30 in the flow direction of the sheet glass SG, and transport the sheet glass SG. The pull-down rollers 81a to 81g constitute a conveying device that conveys the sheet glass SG downward. The pull-down rollers 81a to 81g are disposed in the cooling chamber 80 at intervals along the flow direction. In the example shown in FIG. 3 and FIG. 4, the pulling-down rollers 81 a to 81 g are disposed in each space partitioned by the heat insulating member 80 b. The pulling rollers 81a to 81g are disposed in an area in the cooling chamber 80 where the temperature of the sheet glass SG is equal to or lower than the annealing point. The region where the temperature of the sheet glass SG is lower than or equal to the annealing point is the region where the temperature of the central region of the sheet glass SG is lower than or equal to the annealing point, and the sheet glass SG passes through the annealing and strain points and is near room temperature. The region in the cooling chamber 80 along the flow direction which is cooled to the temperature of The annealing point is the temperature at which the viscosity is 10 ¹³ poise, which is 715.0 ° C. here. In the example shown in FIG. 3 and FIG. 4, the position where the temperature of the sheet glass SG is the gradual cooling point is between the heat insulating member 80 b on the most upstream side in the conveying direction and the conveying direction of the pulling roller 81 a.
The pulling rollers 81a to 81g are disposed 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). Thereby, the pulling-down rollers 81a to 81g pull down the sheet glass SG downward while in contact with the surfaces on both sides in the thickness direction of the sheet glass SG in the regions on both sides in the width direction of the sheet glass SG. The pulling-down rollers 81a to 81g disposed on both sides in the thickness direction of the sheet glass SG operate in pairs, and the pair of pulling-down rollers 81a, 81a,... Pulls the sheet glass SG downward.

  The pulling rollers 81a to 81g are driven by a pulling roller drive motor 391 (see FIG. 5). Further, each of the pulling rollers 81a to 81g rotates in the direction in which the upstream portion approaches the sheet glass SG. The circumferential speed of the pulling rollers 81a to 81g is larger as the pulling roller is positioned downstream. That is, among the plurality of pulling rollers 81a to 81g, the circumferential velocity of the pulling roller 81a is the smallest, and the circumferential velocity of the pulling roller 81g is the largest.

  In the conveying step, the control device 500 controls each pair of pulling rollers 81a to 81g based on the measurement result of a pressure sensor (not shown) that measures the pressure contact between the rollers. Position control. Specifically, the relative position of the one roller to the other roller is such that one of the pair of pulling rollers 81a to 81g presses the other roller with a constant force across the sheet glass SG. Position is controlled.

The pull-down rollers 81a to 81g sandwich the high-temperature sheet glass SG, and are thus air-cooled by an air-cooled tube, for example, passed inside the pull-down rollers 81a to 81g to prevent deformation due to heat. The temperature of the sheet glass SG is lowered (the viscosity is increased) in the inclined region where the pulling rollers 81a to 81g sandwich the sheet glass SG. In particular, when the sheet thickness of the central region of the sheet glass SG is to be formed into a thin plate of 0.7 mm or less, preferably 0.4 mm or less, the holding heat of the sheet glass SG is small, and the sheet glass SG It is susceptible to 81g. When the viscosity of the inclined region held by the pulling-down rollers 81a to 81g increases, a difference in viscosity with other regions adjacent to the inclined region occurs, which causes distortion and the like. Therefore, by realizing a temperature profile such that the temperature of the sheet glass SG becomes uniform in the width direction, distortion occurs in the inclined region held by the pulling rollers 81a to 81g and the region adjacent to the inclined region. Suppress.
The pull-down rollers 81a to 81g are configured to be movable in the width direction in order to adjust the position (sandwich position) where the pull-down rollers 81a to 81g hold the sheet glass SG. The holding positions of the pulling rollers 81a to 81g are previously adjusted before the method of manufacturing the glass substrate, but may be adjusted in the method of manufacturing the glass substrate as described later.

(2-6) Heater The heater 82 (82a to 82g) is provided inside the cooling chamber 80, and adjusts the temperature of the internal space of the cooling chamber 80. Specifically, a plurality of heaters 82a to 82g are disposed in the flow direction of the sheet glass SG and in the width direction of the sheet glass SG. In the example shown in FIG.3 and FIG.4, seven heaters 82a-82g are arrange | positioned at intervals in the flow direction of the sheet glass SG, and are arrange | positioned for every space partitioned off by the heat insulation member 80b. The heaters disposed in each space are configured, for example, such that seven heater elements (not shown) are arranged in the width direction of the sheet glass. The seven heater elements respectively heat-treat the central area CA of the sheet glass SG and the areas R and L on both sides of the sheet glass SG, including the inclined areas held by the pulling rollers 81a to 81g. The outputs of the heaters 82a to 82g are controlled by a control device 500 described later. Thereby, the ambient temperature in the vicinity of the sheet glass SG passing through the inside of the cooling chamber 80 is controlled, and the temperature control of the sheet glass SG is performed. As a result, the sheet glass SG is cooled so that the temperature of the sheet glass SG sequentially decreases along the transport direction. By this temperature control, the sheet glass SG shifts from the viscous region to the elastic region through the visco-elastic region. In the cooling chamber 80, the temperature of the sheet glass SG is cooled from the temperature near the annealing point to the temperature near room temperature by the control of the heaters 82a to 82g.

  The heater element adjusts the ambient temperature in the vicinity of the sheet glass SG so that the output is controlled independently by the control device 500 and the predesigned temperature profile is realized in the sheet glass SG.

  For example, a thermocouple 380 is provided in the vicinity of each of the heaters 82a to 82g as a means for detecting the ambient temperature. Specifically, the plurality of thermocouples 380 are arranged at intervals in the flow direction of the sheet glass SG and in the width direction of the sheet glass SG. The thermocouple 380 detects the temperature of the central portion C of the sheet glass SG and the temperatures of the regions R and L on both sides of the sheet glass SG. The outputs of the heaters 82 a to 82 g are controlled based on the ambient temperature detected by the thermocouple 380.

(2-7) Cutting Device The cutting device 90 cuts the sheet glass SG cooled to a temperature near room temperature in the cooling chamber 80. Specifically, the cutting device 90 cuts along a scribe line formed in the sheet glass SG to separate an end and a boundary area, cuts a central area of the sheet glass SG into a predetermined length, and further Cut to size. The cutting device 90 cuts the sheet glass SG at predetermined time intervals. Thereby, the sheet glass SG becomes a plurality of glass plates. The cutting device 90 is driven by a cutting device drive motor 392 (see FIG. 5).

(2-8) Control Device The control device 500 includes a CPU, a RAM, a ROM, a hard disk and the like, and controls each part of the glass substrate manufacturing apparatus 100. FIG. 5 is a block diagram showing an example of the configuration of the control device 500 according to an embodiment.

  Specifically, as shown in FIG. 5, control device 500 receives signals from various sensors (for example, thermocouple 380) and switches (for example, main power switch 381) included in glass substrate manufacturing apparatus 100. It controls the cooling unit 60, the heaters 82a to 82g, the cooling roller drive motor 390, the pull-down roller drive motor 391, the cutting device drive motor 392, and the like.

(Transporting process)
FIG. 6 is a view for explaining the nipping position of the pulling-down roller in the conveyance step. The cross section of the area | region R of the one side of the width direction of the sheet glass SG is shown by FIG. In the following description, among the pull-down rollers 81a to 81g, the pull-down roller 81a will be representatively described, but the pinching positions of the pull-down rollers 81b to 81g are also adjusted similarly to the pull-down roller 81a. In FIG. 6, the holding position of the cooling roller 51 is also shown.

  In the forming step, as described above, the inclined area SA located at the boundary between the central area CA and the end SP is formed. As illustrated, the area including the slope area SA and the end portion SP has a bulb-like shape in cross-sectional view, and the degree of the slope of the thickness changes in the width direction. Specifically, as the inclination of the thickness increases as it proceeds outward in the width direction from the side of the central area CA, the thickness decreases. The area in the width direction outside the position where the inclination of the inclination area SA becomes 0 is the end SP.

The inclined area SA is an area where the thickness is inclined such that the thickness of the sheet glass SG becomes thicker toward the outer side in the width direction, and has a thickness gradient along the width direction. In such an inclined area SA, a thickness difference (deviation) occurs at the position (width direction area) of the sheet glass SG facing the pulling roller 81a, and the sheet glass SG facing the both ends in the width direction of the pulling roller 81a. A thickness difference exists between the positions A and B. For this reason, in the inclined area SA, the contact area between the pulling roller 81a and the sheet glass SG is small, and the pressure contact force that the sheet glass SG receives from the pulling roller 81a tends to be uneven. As a result, the sheet glass SG is nipped from the pulling roller 81a with a locally large pressure contact force. The sheet glass SG is cooled to a temperature below the vicinity of the annealing point and hardened in the cooling chamber 80, and therefore, depending on the nipping position of the pull-down roller 81a, there is a possibility that a scratch may occur. When such a scratch is present in the sheet glass SG, when the sheet glass SG is cut in the downstream process, the scratch may develop and the sheet glass SG may be broken.
In the present embodiment, at the holding position where the inclination of the thickness of the portion of the sheet glass SG facing the pull-down roller 81a is smaller than the allowable value in the tilt area SA, the pull-down roller 81a is the sheet glass SG. Hold the In the region where the inclination of the thickness of the portion of the sheet glass SG opposed to the pulling roller 81a is smaller than the allowable value, the inclination of the thickness of the sheet glass SG is small. The contact area is larger than in the region where the nipping position is equal to or more than the allowable value, and the non-uniformity of the pressure contact force that the sheet glass SG receives from the pull-down roller 81a is alleviated. For this reason, the sheet glass SG is suppressed from being pinched by the pulling roller 81a locally with a large pressure contact force, and the generation of a scratch on the sheet glass SG is suppressed. In addition, the inclination of thickness is represented by the thickness difference of the part of the sheet glass SG which opposes a pulling-down roller so that it may mention later. In addition, at least a part of the holding position of the pull-down roller may be in the inclination region. Such an aspect includes an aspect in which the widthwise outer end of the draw-down roller is located at the widthwise inner end of the inclined region.

As described above, the sloped area SA generally has a greater degree of thickness slope as it proceeds from the side of the central area CA to the outer side in the width direction. In other words, in the inclined area SA, the degree of inclination of the thickness of the sheet glass SG decreases as the central area CA is approached. For this reason, as the holding position is positioned at the inner position in the width direction in the inclined area SA, the unevenness of the pressure contact force received from the pulling roller 81a of the sheet glass SG is greatly alleviated, thereby suppressing the generation of a scratch. The effect is higher. The allowable value is set such that the pulling-down roller 81a sandwiches the sheet glass SG in such a region.
In the inclined area SA, not only the thickness of the sheet glass SG at a position A facing the end in the width direction of the pull-down roller 81a is larger than the thickness of the central area CA, but also the thickness of the central area CA. Also included is an area equal to the width of the sheet glass SG at a position B opposite to the widthwise outer end of the pull-down roller 81a that is larger than the thickness of the central area CA.

  Specifically, the allowable value is a value determined in accordance with the thickness of the central area CA such that the thickness difference (deviation) between the position A and the position B of the sheet glass SG is equal to or less than a predetermined value. It represents by the value of the said thickness difference in the range of the width direction length of the roller 81a. The reason for the value corresponding to the thickness of the central area CA is that the size of the thickness difference in the inclined area SA largely depends on the thickness of the central area CA, and even in the same width direction position of different sheet glasses SG The reason is that the thickness largely changes depending on the thickness of the central area CA. In addition, since the magnitude of the thickness difference of the allowable positions A and B depends on the width (length along the width direction) of the pulling-down roller 81a, the tolerance is the thickness instead of the value of the thickness difference. The difference may be determined so that the value obtained by dividing the difference by the width of the pull-down roller 81a is equal to or less than a predetermined value.

Here, FIG. 7 shows, as an example, a graph representing the relationship between the thickness of the central area CA and the thickness of the sheet glass SG at the positions A and B, respectively. In FIG. 7, the graph passing through the round plot represents the upper limit of the thickness of the desired sheet glass SG at position A, and the graph of the square plot represents the upper limit of the thickness of the desired sheet glass SG at position B. The upper limit value means the height in the thickness direction of the positions A and B with reference to the main surface of the central area CA.
Using such a relationship, for example, in the case of producing sheet glass SG having a thickness of central area CA of 0.7 mm, upper limit 30 μm of the desired thickness at position A and the desired thickness at position B The difference 70 μm from the upper limit 100 μm is set as the allowable value of the thickness difference. That is, the holding position of the pull-down roller 81a is adjusted so as to be positioned inward in the width direction from the position where the thickness difference is 70 μm or less in the inclination area SA, and in the example shown in FIG. By adjusting the nipping position in this manner, the unevenness of the pressure contact force that the sheet glass SG receives from the pulling roller 81a is alleviated compared to the case where the sheet glass SG is nipped on the outside in the width direction from the line PL. It is suppressed that SG generate | occur | produces a wound. If the pinching position of the pulling-down roller 81a is adjusted at least within a region where the inclination of the thickness of the portion of the sheet glass SG facing the pulling-down roller 81a is smaller than the allowable value, the thickness of the portion is the above Although it is not necessary to adjust the position A and the position B within the area that is equal to or less than the upper limit value of the desired thickness (allowable thickness described later), the holding position of the pulling roller 81a is further It is preferable that the thickness of the portion is adjusted in the region where the desired thickness of the position A and the position B is not more than the upper limit value.
Note that the upper limit values of the desirable thicknesses of the position A and the position B are, for example, 15 μm and 80 μm when the thickness of the central area CA is 0.6 mm, and the thickness of the central area CA is 0.5 mm , 5 μm, 60 μm, 1 μm, 40 μm when the thickness of the central area CA is 0.4 mm, less than 1 μm, 30 μm when the thickness of the central area CA is 0.3 mm, the central area CA When the thickness is 0.2 mm, it is less than 1 μm and 20 μm, and when the thickness of the central area CA is 0.1 mm, it is less than 1 μm and 15 μm.
The relationship between the thickness of the central area CA and the thickness of the sheet glass SG at the positions A and B, as shown in FIG. 7, is actually observed when the inclined area SA of the sheet glass SG produced by nipping with a drawdown roller The thickness which does not generate a scratch in the inclined area SA is found and created based on the situation of the scratch. The positions A and B are determined by the widthwise length of the pulling roller 81a. When the width direction length of the pulling-down roller 81a is illustrated, it is 30-150 mm, for example.

  In the adjustment of the holding position of the pulling-down roller 81a, for example, in the inspection process, the thickness distribution in the inclined area SA is obtained by measurement, and in the obtained thickness distribution, the area satisfying the allowable value set in the above manner The holding position can be determined by setting the position in the area where the inclination of the thickness of the sheet glass SG is smaller than the allowable value, and moving the pull-down roller 81a to the set position. The measurement of the thickness distribution will be described later.

  The holding position of the pulling-down roller 81a is preferably a position where the inclination of the thickness is smaller, even in the area where the inclination of the thickness of the portion of the sheet glass SG facing the pulling-down roller 81a is smaller than the allowable value. It is preferable that it is a position where the slope of thickness is the smallest. In the example shown in FIG. 6, the position where the inclination of the thickness is smaller is on the side farther inward in the width direction from the line PL, and when the position B is located at the inner end in the width direction of the inclined area SA Slope is the smallest.

  Further, in addition to the position where the inclination of the thickness of the portion of the sheet glass SG opposed to the pulling-down roller 81a becomes smaller than the allowable value, the holding position of the pulling-down roller 81a is the position A and the position It is preferable that at least one of B is a position at which the thickness is equal to or less than the allowable thickness (the upper limit of the above-described desired thickness). In the region where the thickness is large, for example, the degree of inclination may change due to the sheet glass SG being sandwiched and deformed by the cooling roller 51, and the pressure contact force that the sheet glass SG receives from the pulling roller 81a. May change. For example, in the above-described example of manufacturing the sheet glass SG having a central area CA of 0.7 mm in thickness, the position of the inner end in the width direction of the draw-down roller 81a having a thickness of 30 μm or less at position A; It is preferable that the holding position of the pull-down roller 81a be adjusted to a position that satisfies at least one of the positions of the widthwise outer end of the pull-down roller 81a where the thickness at the position B is 100 μm or less. Further, the pinching position of the pulling-down roller 81a is preferably on the inner side in the width direction than the pinching position of the cooling roller 51 in order to avoid the fluctuation of the pressure contact force described above.

  On the other hand, the nipping position of the pull-down roller 81a is set such that the position B is positioned at the widthwise inner end of the inclined area SA or at the outer side in the widthwise direction from this end. If the position B is positioned inward in the width direction beyond the widthwise inner end of the inclined area SA, no force in the width direction outward can be applied to the sheet glass SG, so the sheet glass SG is a pulling roller There is a possibility that the sheet glass SG may be slipped between the sheet 81 and the sheet 81 a and the sheet glass SG may have a shape defect. In addition, when the position B is positioned inward in the width direction beyond the end excessively, it is necessary to set the cutting position (position where the scribe line S is formed) in the cutting step in the width direction more than the position A Product area will be smaller. The scribe line S is usually set slightly inward in the width direction from the boundary between the central area CA and the slope area SA as in the example shown in FIG.

The holding position of the pull-down roller 81a is adjusted to a position where a predetermined distance L1 or more is opened in the width direction from the position Q of the inner end in the width direction among the positions of the sheet glass SG held by the cooling roller 51. Is preferred.
The surface of the sheet glass SG sandwiched by the cooling roller 51 may have irregularities formed by pressure contact with the cooling roller 51. Therefore, when the sandwiching position is close to the position Q, the thickness of the sheet glass SG When the degree of the inclination of the sheet is largely changed, the pressure contact force that the sheet glass SG receives from the pulling roller 81a may not be stable.
Further, as described above, since the inclined area SA usually has an area in which the thickness inclination is increased as the width area is moved outward from the central area CA, the nipping position is located. If it is close to Q, the force in the width direction outward can not be sufficiently exerted on the sheet glass SG, and the sheet glass SG may slip relative to the pull-down roller 81a during conveyance.
For this reason, the distance L1 is preferably 50% or more of the distance between the cooling roller 51 and the boundary between the inclined area SA and the central area CA, and is, for example, 20 mm or more.
For the same reason, it is preferable that the holding position of the pull-down roller 81a be adjusted to a position where a predetermined distance L2 or more is opened inward in the width direction from the end in the width direction of the sheet glass SG. The distance L2 is preferably 80% or more of the length of the inclined area SA and the end portion SP, and is, for example, 30 mm or more.
In FIGS. 3 and 4, the cooling roller 51 and the pulling rollers 81a to 81g are shown larger than the sizes shown in FIG. Further, in FIG. 3, the sandwiching positions of the sheet glass SG of the cooling roller 51 and the pull-down rollers 81 a to 81 g are shown differently from FIG. 6.

The method of manufacturing the glass substrate preferably further includes a control step of adjusting the nipping position of the pulling roller 81a. In the control step, the holding position of the pulling roller 81a is adjusted in the region of the tilting region SA where the inclination of the thickness of the portion of the sheet glass SG facing the pulling roller 81a is smaller than the allowable value. In the control process, specifically, the control device 500 controls a drive device (not shown) for moving the pull-down roller 81a in the width direction so that the nipping position of the pull-down roller 81a is adjusted.
In the control step, it is determined whether or not the pinching position of the pull-down roller 81a is in a region where the inclination of the thickness is smaller than the allowable value, for example, at constant time intervals, and the pinching position is as described above If it is determined that the inclination of the thickness is within the range where the inclination is smaller than the allowable value, the holding position of the pull-down roller 81a is not changed, and the operation is continued, and the inclination of the thickness is higher than the allowable value. When it is determined that the position is not within the area to be reduced, the control device 500 controls the drive device to pull down the roller 81a so that the nipping position is located within the area where the thickness inclination is smaller than the allowable value. Adjust the width direction position of.
According to this glass substrate manufacturing method, the inclination of the thickness of the sheet glass SG changes during operation, and the holding position of the pulling-down roller 81a is out of the range where the inclination of the thickness is smaller than the allowable value. The feedback position of the pull-down roller 81a is adjusted within a range where the inclination of the thickness is smaller than the allowable value by feedback adjustment of the pinching position, whereby the non-uniform contact pressure received by the sheet glass SG from the pull-down roller 81a Can be mitigated, and the generation of scratches on the sheet glass SG can be suppressed.

It is preferable that the manufacturing method of a glass substrate has the measurement process which measures the inclination of the thickness of sheet glass SG in inclination area | region SA further when it has the said control process. Specifically, the inclination of the thickness of the sheet glass SG can be obtained by associating the thickness of the sheet glass SG measured at a plurality of locations along the width direction in the inclination area SA with each thickness and the position in the width direction it can. The thickness of the sheet glass SG at each widthwise position is measured, for example, using a measuring device (not shown) such as a laser displacement gauge. The measuring device is connected to the control device 500, and is configured to output, to the control device 500, thickness and width direction position information measured at regular time intervals. The control device 500 acquires the inclination of the thickness from the information of the thickness and the width direction position among the information sent from the measuring device, and acquires the inclination of the acquired thickness and the thickness of the central area CA of the sheet glass SG. The above judgment is performed using. The control device 500 may use a thickness set in advance before operation as the thickness of the central region CA, and during the operation, the thickness of the central region CA measured by the measuring means similar to the above-mentioned measuring device You may use. Control device 500 holds information on an allowance according to the thickness of central region CA.
In this glass substrate manufacturing method, feedback adjustment of the holding position is performed based on the thickness of the central area CA, and in particular, when the inclination of the thickness changes due to the thickness of the central area CA, Unevenness of the pressure contact force that the sheet glass SG receives from the pulling roller 81a can be alleviated with high accuracy.

  It is preferable that the thickness inclination tolerance be set for each of the pulling rollers 81a to 81g. In this case, it is preferable that the allowable value be set to a smaller value as the draw-down roller is further positioned downstream. The sheet glass SG is lower in temperature and harder as it is located in the downstream side, so it is more easily scratched and more likely to be cracked than the portion located on the upstream side. However, as described above, if it is set such that the lower the lowering roller located on the downstream side, the smaller the allowable value of the thickness inclination, the lower the lowering roller located on the downstream side, the inclination of the plate thickness Because the nipping position is adjusted to the portion of the sheet glass SG having a small value, the non-uniformity of the pressure contact force applied to the sheet glass SG is largely alleviated. As described above, by setting the allowable value for each of the pulling rollers 81a to 81g and defining the size thereof, it is possible to suppress the occurrence of a scratch in the region on both sides of the sheet glass SG throughout the transport direction. The temperature is higher as the portion of the sheet glass SG located on the upstream side is higher and softer, so the holding position of the pull-down roller is located on the downstream side even if the sheet glass SG has a large inclination of sheet thickness. Scratches are less likely to occur compared to the portion of the sheet glass SG located.

  According to the present embodiment, the pulling-down roller 81a holds the sheet glass SG at the holding position where the inclination of the thickness of the portion of the sheet glass SG facing the pulling-down roller 81a is adjusted to be smaller than the allowable value. Thus, the non-uniformity of the pressure contact force that the sheet glass SG receives from the pulling roller 81a is alleviated as compared with the case where the pinching position is located outside the region smaller than the allowable value. For this reason, the sheet glass SG is suppressed from being pinched by the pulling roller 81a locally with a large pressure contact force, and the generation of a scratch on the sheet glass SG is suppressed.

  As mentioned above, although the manufacturing method of a glass substrate of the present invention and a glass substrate manufacturing device were explained in detail, the concrete composition of the present invention is not restricted to said embodiment, In the range which does not deviate from the gist of an invention It can be changed.

DESCRIPTION OF SYMBOLS 11 Melt apparatus 12 Fining apparatus 40 Forming apparatus 41 Molding body 51 Cooling roller 60 Cooling unit 81a-81g Pull-down roller 82a-82g Heater 90 Cutting apparatus 100 Glass substrate manufacturing apparatus 500 Control apparatus

Claims (9)

Forming the molten glass using an overflow down draw method to form a glass plate;
And conveying the glass sheet downward while holding the regions on both sides in the width direction of the glass sheet between at least a pair of conveyance rollers,
In the forming step, an inclined region in which the thickness of the glass plate is inclined in the width direction is formed in the regions on both sides such that the thickness of the glass plate becomes thicker toward the outer side in the width direction.
The position where the transport roller sandwiches the glass plate in the transport step is adjusted within a range in which the inclination of the thickness of the portion of the glass plate facing the transport roller becomes smaller than the allowable value in the inclination region. The method for producing a glass substrate, characterized in that In the forming step, before sandwiching the glass plate by the transport roller, the regions on both sides of the glass plate are pinched by a cooling roller disposed upstream of the transport roller in the transport direction,
2. The glass according to claim 1, wherein a position at which the transport roller sandwiches the glass plate is adjusted to a position spaced a predetermined distance or more inwardly in the width direction from the position of the glass plate sandwiched by the cooling roller. Method of manufacturing a substrate And a control step of adjusting a position at which the transport roller clamps the glass plate,
In the control step, the position at which the transport roller sandwiches the glass plate is within a range where the thickness of the portion of the glass plate facing the transport roller has an inclination smaller than an allowable value in the tilt region. The manufacturing method of the glass substrate of Claim 1 or 2 adjusted. The method further comprises a measuring step of measuring the thickness slope of the portion of the glass sheet in the sloped region,
The said control process adjusts the position which the said conveyance roller clamps the said glass plate based on the measurement result of the thickness of the center area of the width direction of the said glass plate, and the inclination of the said thickness. Glass substrate manufacturing method.   The method of manufacturing a glass substrate according to claim 3, wherein in the control step, a position at which the transport roller sandwiches the glass plate is adjusted in a region where the inclination of the thickness is further reduced.   The position in which the said conveyance roller clamps the said glass plate is adjusted to the position which opened the space | interval more than predetermined by the width direction inner side from the both ends of the width direction of the said glass plate. The manufacturing method of the glass substrate as described in-.   The position in which the said conveyance roller clamps the said glass plate is adjusted in the area | region where the thickness of the part of the said glass plate facing the said conveyance roller becomes below in an allowance thickness. The manufacturing method of the glass substrate of 1 item. In the conveying step, the glass plate is conveyed downward while the regions on both sides are held by a plurality of conveying rollers arranged at intervals in the conveying direction.
The method for manufacturing a glass substrate according to any one of claims 1 to 7, wherein the allowable value is set to a smaller value as the transport roller is positioned on the downstream side in the transport direction. A forming apparatus for forming molten glass by an overflow down draw method to form a glass sheet;
And a conveyance device configured to convey the glass sheet downward while sandwiching the regions on both sides in the width direction of the glass sheet with at least a pair of conveyance rollers,
The forming apparatus forms, in the regions on both sides, an inclined region in which the thickness of the glass plate is inclined in the width direction such that the thickness of the glass plate becomes thicker toward the outer side in the width direction.
The position at which the transport roller sandwiches the glass plate is adjusted within a range in which the slope of the thickness of the portion of the glass plate facing the transport roller is smaller than the allowable value in the slope region. A glass substrate manufacturing apparatus characterized by

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