JP2019064846A - Method and apparatus for manufacturing glass substrate - Google Patents

Abstract

To suppress the variation of the shape of a glass plate during conveyance.SOLUTION: In the method for manufacturing a glass substrate, a conveyance roller pair is arranged in a temperature range in which the temperature of the glass plate is equal to or less than a strain point, and the conveyance roller pair has a first roller and a second roller sandwiching a sheet glass therewith and contacted by pressure to the first roller. Since a position of the rotation axis center of the first roller in a second conveyance roller pair is positioned on a side away from a straight line extended vertically downward from a molding to a position of the rotation axis center of the first roller in a first conveyance roller pair, the second conveyance roller pair arranged below the first conveyance roller pair in the conveyance roller pairs shifts regions on both sides on a side away from a straight line to a central region between the regions on both sides and curves and conveys the glass plate so that the glass plate has a convex surface in a conveyance step.SELECTED DRAWING: Figure 6

Description

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

  The method of manufacturing a glass plate (sheet glass) using the down draw method is known. 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 area is the product area. In the downdraw method, in order to stably convey the formed sheet glass downward, an area (sandwich area) located at the boundary between the central area and the end of the sheet glass is nipped by the conveyance roller. The sheet glass is cooled while being conveyed downward in the lehr.

JP, 2013-212987, A

  When the sheet glass is conveyed, an air flow in which air warmed by the sheet glass flows upward is generated on both sides in the thickness direction of the sheet glass. Under the influence of the air flow, for example, in a cross section orthogonal to the flow direction of the sheet glass, the sheet glass may be curved so as to be convex or concave on one side. The curved sheet glass may come into contact with a heat insulating member or the like sandwiching the sheet glass from both sides, and may cause scratches or cracks in the sheet glass. In addition, the sheet glass may also be cracked due to the occurrence of a phenomenon such as inversion where the sheet glass is convex on one side and depression where it is switched, or hunting which repeats the inversion. Moreover, when the stress which generate | occur | produced in sheet glass by inversion and hunting is transmitted to the area | region where temperature of sheet glass becomes more than a strain point, distortion may be formed in sheet glass.

  Then, an object of this invention is to provide the manufacturing method of a glass substrate which can suppress the change of the shape of the glass plate in conveyance, and a glass substrate manufacturing apparatus.

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 a plurality of conveyance roller pairs provided in the conveyance direction of the glass sheet,
The transport roller pair is disposed in a temperature range where the temperature of the glass plate is equal to or lower than the strain point, and each of the transport roller pair is pressed against the first roller and the first roller across the sheet glass. And a second roller,
With respect to the second transport roller pair disposed below the first transport roller pair in the transport roller pair, the position of the rotational axis of the first roller is the center of the rotational axis of the first roller of the first transport roller. With respect to the position, by being located on the side away from the straight line extending vertically downward from the molded body, in the transfer step, the regions on the both sides are straight lines with respect to the central region between the regions on the both sides. And moving the glass plate so that the glass plate has a convex curved surface, and moving the glass plate so as to have a convex curved surface.

  With regard to the third transport roller pair disposed below the second transport roller pair in the transport roller pair, the position of the rotational axis center of the first roller is the rotational axis of the first roller of the second transport roller pair It is preferable to be located on the side away from the straight line with respect to the center position.

  The distance D2 between the position of the rotation axis of the first roller of the third conveyance roller pair and the position of the rotation axis of the first roller of the second conveyance roller along the direction away from the straight line is The distance D1 between the position of the rotation axis of the first roller of the second conveyance roller pair and the position of the rotation axis of the first roller of the first conveyance roller pair along the direction away from the straight line preferable.

Another aspect of the present invention is a glass substrate manufacturing apparatus,
A forming apparatus for forming a glass sheet by forming molten glass using an overflow downdraw method,
The forming apparatus is provided in the temperature direction where the temperature of the glass sheet is equal to or lower than the strain point at intervals in the transport direction of the glass sheet, and holds the areas on both sides in the width direction of the glass sheet. It has a plurality of transport roller pairs for transporting the glass plate downward,
Each of the conveyance roller pair has a first roller, and a second roller press-contacted to the first roller with the sheet glass interposed therebetween;
With respect to the second transport roller pair disposed below the first transport roller pair in the transport roller pair, the position of the rotational axis of the first roller is the center of the rotational axis of the first roller of the first transport roller. By being positioned on the side away from the straight line extending vertically downward from the molded body with respect to the position, the transport roller pair is configured such that the area on the both sides is the center area between the areas on the both sides. It is characterized in that the glass sheet is curved and conveyed such that the glass sheet has a convex curved surface while being shifted to the side away from the straight line.

  ADVANTAGE OF THE INVENTION According to this invention, the change of the shape of the glass plate in conveyance can be suppressed.

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 side view showing the 1st conveyance roller pair and the 2nd conveyance roller pair. It is a figure which shows the cross section orthogonal to the flow direction of the glass plate conveyed. It is a figure which shows the 1st-3rd conveyance roller pair by one Embodiment. It is a figure which shows the 1st-3rd conveyance roller pair by one Embodiment.

  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 FIGS. 1 and 2, a plurality of processes included in the method of manufacturing a glass substrate and a manufacturing apparatus 100 of a glass substrate 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.

Melting process S1 is a process in which the raw material of glass is melted. The glass raw material is introduced into the melting device 11 disposed upstream after being formulated to have a desired composition. 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 (ear, end) located at the end in the width direction and a central region in the width direction sandwiched between the sides. The thickness of the side portion of the sheet glass SG is formed thicker than the thickness of the central region. The central region of the sheet glass SG is a region to be a product of a glass substrate having a constant thickness. The plate thickness of the central region of the sheet glass SG is formed into a thin plate of, for example, 0.4 mm or less. In addition, the width direction of the sheet glass SG is a direction orthogonal to the direction (flow direction, conveyance direction) in which the sheet glass SG flows down and the thickness direction of the sheet glass SG.

  In the cooling step S4, the sheet glass SG is conveyed downward for cooling while holding the regions on both sides in the width direction of the sheet glass SG with a pulling-down roller, which will be described later, provided in the conveyance direction of the sheet glass SG Cold). The area pinched by the pulling-down roller is a pinching area located at the boundary between the central area and the side portion. 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.

  The sheet glass SG cut into a predetermined size is then subjected to a process such as end face processing to become a glass substrate.

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

(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 forming apparatus 40 mainly includes a formed body 41, a partition member 50, a cooling roller 51, a cooling unit 60, pulling rollers (conveying rollers) 81a to 81g, heaters 82a to 82g, and a cutting device 90. , Is composed of. 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.

  The molded body 41 also has an inlet 42 (see FIG. 4) at the first end. 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 (left and right direction in FIG. 4) of the molded body 41. Specifically, the groove 43 extends from the first end to the second end opposite to the first end. 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 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, among the areas on both sides of the sheet glass SG, the nipping area is nipped by the two pairs of cooling rollers 51, 51,.

The cooling roller 51 is air-cooled by an air-cooling pipe passed through inside. The cooling roller 51 contacts the side portions (ears, ends) R, L of the sheet glass SG and rapidly cools the side portions (ears, ends) R, L of the sheet glass SG by heat conduction (quenching step ). The viscosity of the side portions R and L of the sheet glass SG in contact with the cooling roller 51 is not less than a predetermined value (specifically, 10 ^9.0 poise).

  The cooling roller 51 is rotationally driven by a cooling roller drive motor 390 (see FIG. 5). The cooling roller 51 not only cools the side portions R and L of the sheet glass SG, but also has a function of pulling 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 annealing point is the temperature of the sheet glass SG when the viscosity is 10 ¹³ poise, and in this case, it is 715.0 ° C. 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 region of the sheet glass SG is a region located between both sides (both ears, both ends) 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 side portions (ears, ends) R, L 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 side portions R and L (both ends in the width direction) 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 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 at least partially disposed in the area in the cooling chamber 80 where the temperature of the sheet glass SG is equal to or less than the strain. The area where the temperature of the sheet glass SG is equal to or less than the strain point means the area where the temperature of the entire area of the sheet glass SG in the width direction is equal to or less than the strain point. The strain point is the temperature of the sheet glass SG when the viscosity is 10 ^14.5 Poise. In the example shown in FIG. 3 and FIG. 4, the position where the temperature of the sheet glass SG is the strain point is, for example, between the conveying direction of the pulling roller 81 c and the pulling roller 81 d.
The pulling-down 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). As a result, the pulling rollers 81a to 81g contact the sheet glass SG while contacting the surfaces on both sides in the thickness direction of the sheet glass SG of the both sides (both ears, both ends) R and L in the width direction of the sheet glass SG. Pull it down. 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 (conveying roller pairs) 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). The pulling rollers 81a to 81g rotate in the direction in which the upstream side portion approaches the sheet glass SG.

(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 heater elements are disposed at positions opposite to the areas on both sides of the sheet glass SG and the area between the areas on both sides. The heater 82 is disposed farther from the sheet glass SG than the pull-down 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. Specifically, the temperature profile is designed such that the temperature of the sheet glass SG is uniform in the width direction. Here, that the temperature is uniform means that the temperature forming the temperature distribution in the width direction at least in the sandwiching region and the central region is within ± 20 ° C. with respect to the average temperature of the sandwiching region and the central region . By cooling so that the temperature of the sheet glass SG becomes uniform in the width direction, the occurrence of distortion in the holding area of the sheet glass SG and the area adjacent to the holding area is suppressed.

  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 side portions R and L 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 into a predetermined 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).

  Thus, when manufacturing a glass plate with the manufacturing apparatus 100 of a glass substrate, the formation process of shape | molding sheet glass SG using the overflow down draw method from molten glass FG, the area | region of the both sides of the width direction of a glass plate A conveyance step of conveying the sheet glass SG downward is performed while being sandwiched by a plurality of conveyance roller pairs provided in the conveyance direction of the sheet glass SG. In the present embodiment, the sheet glass is cooled in the transport step.

(2-8) Control Device The control device 500 includes a CPU, a RAM, a ROM, a hard disk, and the like, and controls various devices included in 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, the control device 500 includes various sensors (eg, thermocouple 380, roller pressure sensor 382) and switches (eg, main power switch 381) included in the glass substrate manufacturing apparatus 100. Control the cooling unit 60, heaters 82a to 82g, cooling roller drive motor 390, pull-down roller drive motor 391, cutting device drive motor 392, pull-down roller position control motors 394a to 394g, etc. . The pulling roller position control motors 394a to 394g are motors for moving the positions of the pulling rollers 81a to 81g in order to control the position of the pulling rollers 81a to 81g described later. The roller pressure sensor 382 is a sensor that measures the force with which the pulling rollers 81a to 81g press the sheet glass SG. The roller pressure sensor 382 is provided at each position of the pulling rollers 81a to 81g.
The control device 500 further performs position control of the pulling rollers 81a to 81g using the pulling roller position control motors 394a to 394g in the conveyance step. The transport process will be described below.

(3) Conveying Step In the conveying step, in the control device 500, the pulling-down rollers 81a to 81g are position-controlled based on the measurement result of the roller pressure sensor 382. Specifically, of the pair of first rollers and second rollers forming the pair of pulling rollers 81a to 81g, the second roller is pressed against the first roller with a constant force across the sheet glass SG. The relative position of the second roller to the first roller is controlled.

In the following description, among the pulling rollers 81a to 81g, each pair of pulling rollers disposed in a region where the sheet glass SG is at or below the strain point is a pair of the first roller A1 and the second roller B1, and It is described as a pair of the roller A2 and the second roller B2, or further as a pair of the first roller A3 and the second roller B3. FIG. 6 is a side view showing a pair of a first roller A1 and a second roller B1 and a pair of a first roller A2 and a second roller B2 as a first conveying roller pair and a second conveying roller pair. .
In the present embodiment, among the transport roller pairs disposed in the region where the temperature of the sheet glass SG is equal to or lower than the strain point, a pair of the first roller A1 and the second roller B1 (first transport roller pair), and The position of the center of the rotation axis of the first roller A2 with respect to the pair of the first roller A2 and the second roller B2 arranged below (second conveying roller pair) is, as shown in FIG. 6, the position of the first roller A1. With respect to the position of the center of rotation axis, it is located on the side (right side in FIG. 6) away from an imaginary straight line S extending vertically downward from the molded body 41. As described above, the center of the rotation axis of the first roller A2 is displaced with respect to the center of the rotation axis of the first roller A1, so that the areas on both sides of the sheet glass SG are as shown in FIG. The sheet glass SG is conveyed in a curved state so as to have a convex curved surface SG1 with a deviation from the virtual straight line S to the central area between the two areas.

  FIG. 7 is a view showing a cross section orthogonal to the flow direction of the sheet glass SG to be conveyed, as viewed from the upstream side. In FIG. 7, the cross section of the portion of the sheet glass SG on the upstream side in the flow direction with respect to the pair of the first roller A1 and the second roller B1 is indicated by an alternate long and short dash line. On the upstream side of the pair of the first roller A1 and the second roller B1, the conveyance path of the sheet glass SG linearly extends along the imaginary straight line S. In this embodiment, when the sheet glass SG passes through the pair of the first roller A1 and the second roller B1, the pair of the first roller A2 and the second roller B2 has a center of rotation axis of the first roller A2 as the first roller. As described above, the side portions L and R on both sides of the sheet glass SG are deviated from the imaginary straight line S with respect to the rotation axis center of A1. On the other hand, in the central area CA, since the weight of the sheet glass SG acts largely, the amount of deviation toward the side away from the imaginary straight line S is small compared to the side portions L and R on both sides. As a result, the sheet glass SG is curved so as to have a convex curved surface SG1 as shown by a solid line in FIG. In the present embodiment, by conveying the sheet glass SG in such a curved state, it is possible to suppress the change in shape under the influence of the air flow flowing in the vicinity of the sheet glass SG. Thereby, it is suppressed that sheet glass SG contacts heat insulation member 80b etc. during conveyance, and a scratch and a crack arise in sheet glass SG. In addition, by conveying the sheet glass SG in a curved state, a phenomenon such as inversion where the sheet glass SG is convex on one side in the thickness direction and switching when it is recessed occurs or hunting which repeats the inversion occurs. The occurrence of these phenomena suppresses the occurrence of sheet glass cracking. In addition, when stress generated by inversion and hunting is transmitted to the area of the sheet glass SG where the temperature of the sheet glass SG is equal to or higher than the strain point, distortion is formed in the sheet glass SG. By suppressing the occurrence of a phenomenon such as hunting, the strain formed on the sheet glass SG is suppressed.

According to one embodiment, as illustrated in FIG. 8, the position of the center of the rotation axis of the first roller A3 with respect to the third transport roller pair disposed below the second transport roller pair in the transport roller pair is It is preferable to be located on the side away from the virtual straight line S with respect to the position of the center of rotation axis of the first roller A2 of the second conveyance roller pair. In other words, it is preferable that the positions of the centers of rotation axes of the first rollers A1, A2, and A3 be positioned so as to be away from the imaginary straight line S on the downstream side. Thereby, the state which curved the sheet glass SG can be stabilized, and the effect that the shape of the sheet glass SG becomes difficult to change during conveyance increases. FIG. 8 is a view showing first to third pairs of transport rollers according to an embodiment.
On the other hand, when the third conveyance roller pair is located on the side closer to the imaginary straight line S with respect to the second conveyance roller pair, the sheet glass SG passes through the second conveyance roller pair, The side portions L and R on both sides are shifted to the side approaching the imaginary straight line S, and curved so as to have a convex curved surface protruding on the opposite side (left side in FIG. 7) to the example shown by solid lines in FIG. As described above, when the projecting side of the sheet glass SG is switched in the middle of the conveyance path, the sheet glass SG becomes flat in the width direction in a partial area in the conveyance direction. The sheet glass SG which is flat in the width direction is susceptible to air flow, and its shape is easily changed.
As described above, in the case where the position of the center of rotation axis of the first rollers A1, A2 and A3 is positioned so as to move away from the virtual straight line S as it goes downstream, Since the sheet glass SG does not have a flat portion in the width direction in the middle, the shape of the sheet glass SG is not easily changed by the influence of the air flow.

In this case, as shown in FIG. 9, the distance D2 between the position of the rotation axis of the first roller A3 and the position of the rotation axis of the first roller A2 along the direction away from the imaginary straight line S is It is preferable that the distance D1 between the position of the rotation axis of the first roller A2 and the position of the rotation axis of the first roller A1 along the direction away from the imaginary straight line S be larger than the distance D1. When the distance D2 is larger than the distance D1, the curved state of the sheet glass SG can be more stably transported, and the effect of making the shape of the sheet glass SG less likely to change during transportation is further enhanced. FIG. 9 is a view showing first to third pairs of transport rollers according to an embodiment.
On the other hand, when the distance D becomes excessively large, the degree of curvature of the sheet glass SG may be too large, which may make it difficult to convey the sheet glass SG. Moreover, since the inclination of the sheet glass SG when passing the conveyance roller pair located downstream is large, a crack may occur due to this. For this reason, according to one embodiment, the distance D with respect to the distance L is such that the ratio D / L of the distance D to the distance L between the pair of conveyance rollers adjacent in the conveyance direction is 0.001 to 0.02. It is preferable to set. Since the sheet glass SG is nipped by the pair of transport rollers and transported downward while being pulled in the width direction, the sheet glass SG is curved even if the ratio D / L is set to the above-described small range. It can be stabilized. The ratio D / L is preferably larger as it goes downstream, but may be smaller.

  The positional deviation of the first roller of the transport roller pair downstream of the upstream transport roller pair with respect to the first roller of the upstream transport roller pair corresponds to the plurality of transport roller pairs disposed in the area where the temperature of the sheet glass SG is below the strain point. Although it is preferable to set in any of, it may be set in at least one of the plurality of conveyance roller pairs.

According to one embodiment, regarding the shortest length of the horizontal gap between the heat insulating member 80b and the sheet glass SG (the gap between the portion of the heat insulating member 80b facing the convex curved surface SG1 and the convex curved surface SG1) The gap between the heat insulating member 80b located below the second transport roller pair and the sheet glass SG is larger than the gap between the heat insulating member 80b located above the second transport roller pair and the sheet glass SG Preferably, the position of the end of the heat insulating member 80b disposed close to the sheet glass SG is adjusted. Thereby, the contact with the heat insulation member 80b of the sheet glass SG can be suppressed, interrupting the movement of heat from the upper side to the lower side.
In this case, when the distance D2 is larger than the distance D1, the gap between the sheet glass SG and the heat insulating member 80b located below the third conveyance roller pair is the second conveyance roller pair and the third conveyance roller pair. The position of the end portion of the heat insulating member 80b disposed close to the sheet glass SG is adjusted so as to be larger than the gap between the heat insulating member 80b positioned between the conveying direction of the pair of conveying rollers and the sheet glass SG. Is preferred.

  According to the present embodiment, by conveying the sheet glass SG in a curved state, it is possible to suppress the change in shape under the influence of the air flow flowing in the vicinity of the sheet glass SG. Thereby, it is suppressed that sheet glass SG contacts heat insulation member 80b etc. during conveyance, and a scratch and a crack arise in sheet glass SG.

Although the present embodiment has been described above based on the drawings, the specific configuration is not limited to the above embodiment and can be changed without departing from the scope of the invention.
For example, the pulling rollers 81a to 81g may be arranged at equal intervals in the transport direction, but may be arranged at different intervals in the transport direction. For example, the interval between the pulling-down rollers 81a to 81g adjacent to each other in the transport direction may be larger as the downstream side is located.

DESCRIPTION OF SYMBOLS 11 Dissolution apparatus 12 Fining apparatus 40 Molding 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 (4)

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 a plurality of conveyance roller pairs provided in the conveyance direction of the glass sheet,
The transport roller pair is disposed in a temperature range where the temperature of the glass plate is equal to or lower than the strain point, and each of the transport roller pair is pressed against the first roller and the first roller across the sheet glass. And a second roller,
With respect to the second transport roller pair disposed below the first transport roller pair in the transport roller pair, the position of the rotational axis of the first roller is the center of the rotational axis of the first roller of the first transport roller. With respect to the position, by being located on the side away from the straight line extending vertically downward from the molded body, in the transfer step, the regions on the both sides are straight lines with respect to the central region between the regions on the both sides. A method of manufacturing a glass substrate, wherein the glass plate is curved and conveyed such that the glass plate has a convex curved surface while being shifted to the side away from the glass substrate.   With regard to the third transport roller pair disposed below the second transport roller pair in the transport roller pair, the position of the rotational axis center of the first roller is the rotational axis of the first roller of the second transport roller pair The manufacturing method of the glass substrate of Claim 1 located in the side which distances from the said straight line with respect to the position of a center.   The distance D2 between the position of the rotation axis of the first roller of the third conveyance roller pair and the position of the rotation axis of the first roller of the second conveyance roller along the direction away from the straight line is The distance D1 between the position of the center of the rotation axis of the first roller of the second pair of transport rollers and the position of the center of the rotation axis of the first roller of the first pair of transport rollers along the direction away from the straight line The manufacturing method of the glass substrate of claim 2. A forming apparatus for forming a glass sheet by forming molten glass using an overflow downdraw method,
The forming apparatus is provided in the temperature direction where the temperature of the glass sheet is equal to or lower than the strain point at intervals in the transport direction of the glass sheet, and holds the areas on both sides in the width direction of the glass sheet. It has a plurality of transport roller pairs for transporting the glass plate downward,
Each of the conveyance roller pair has a first roller, and a second roller press-contacted to the first roller with the sheet glass interposed therebetween;
With respect to the second transport roller pair disposed below the first transport roller pair in the transport roller pair, the position of the rotational axis of the first roller is the center of the rotational axis of the first roller of the first transport roller. By being positioned on the side away from the straight line extending vertically downward from the molded body with respect to the position, the transport roller pair is configured such that the area on the both sides is the center area between the areas on the both sides. A glass substrate manufacturing apparatus, characterized in that the glass plate is curved and conveyed such that the glass plate has a convex curved surface while being shifted to a side away from a straight line.

Images