JP7852644B2 - Method for manufacturing flat glass, method for manufacturing wedge-shaped glass, and method for manufacturing laminated glass - Google Patents

Description

This invention relates to a method for manufacturing flat glass, a method for manufacturing wedge-shaped glass, and a method for manufacturing laminated glass. In particular, it relates to a method for manufacturing flat glass in which the cross-section in the width direction perpendicular to the direction of travel of the glass ribbon is convex (the center in the width direction is thicker than both ends in the width direction).

The thickness of plate glass manufactured by the float process is usually constant. However, for example, in head-up displays (HUDs) that display information on the windshield of automobiles, glass of varying thickness is required to prevent double images from appearing to the driver. Therefore, methods for manufacturing plate glass in which the cross-section in the width direction (hereinafter sometimes simply referred to as the width direction) perpendicular to the direction of travel of the glass ribbon is concave, convex, or tapered have been investigated (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses obtaining wedge-shaped glass by cutting a plate glass with a convex cross-section where the center in the width direction is thicker than both ends in the width direction.

International Publication No. 2016/117650 U.S. Patent No. 7,122,242

Typically, a molten metal bath comprises an upstream wall, a downstream wall, and two side walls. Each side wall may be provided with a shoulder to reduce the width of the molten metal bath in the direction of glass ribbon travel, thereby reducing the amount of molten metal within the bath. In such a molten metal bath with shoulders on the side walls, a flow in the opposite direction to the glass ribbon's travel may occur in the portion of the molten metal surface not covered by the glass ribbon. This reverse flow can cause the glass ribbon on the molten metal surface to be observed to move back and forth (swing) in the width direction as it travels.

In particular, when manufacturing a glass plate with a convex cross-section, as described in Patent Document 1, the temperature of the center of the glass ribbon in the width direction is set lower than when manufacturing a glass plate with a constant thickness. This increases the viscosity of the glass ribbon (making it harder), making it more susceptible to the effects of the reverse flow and prone to causing the glass ribbon to swing. Furthermore, when attempting to manufacture wedge-shaped glass by cutting a glass plate with a convex cross-section, as described in Patent Document 1, the cutting position of the glass plate is usually fixed. Therefore, if the aforementioned swing occurs, the wedge angle of the wedge-shaped glass will vary from product to product.

The present invention has been made in view of the above circumstances, and its objective is to provide a method for manufacturing flat glass that can suppress reciprocating movement (swing) in the width direction of the glass ribbon. Furthermore, it aims to provide a method for manufacturing wedge-shaped glass and laminated glass that can suppress variations in the wedge angle of wedge-shaped glass obtained by cutting the flat glass. In this invention, convex-shaped glass means a glass ribbon in which the center in the width direction is thicker than both ends in the width direction, or flat glass obtained from a glass ribbon.

The above objective of the present invention is achieved by the following configuration.
[1] A method for manufacturing a glass plate, comprising floating a glass ribbon on the surface of a molten metal bath and advancing it, and bringing a plurality of top rolls into contact with both ends of the glass ribbon in the width direction to form the glass ribbon into a plate shape,
The molten metal bath comprises an upstream wall, a downstream wall, and two side walls.
Each of the two side walls includes a shoulder that reduces the width of the molten metal bath in the direction of the glass ribbon's movement.
The ratio W/N of the distance W between the two side walls upstream of the shoulder of the molten metal bath and the distance N between the two side walls downstream of the shoulder of the molten metal bath is greater than 1.0 and less than or equal to 1.6.
A method for manufacturing a glass plate, comprising heating the ends of the glass ribbon more strongly in the width direction than the center in the width direction in the upstream region of the molten metal bath, thereby producing a glass plate where the center in the width direction is thicker than the ends.
[2] The method for manufacturing a glass plate according to [1], wherein the glass ribbon is heated at a position 20% from the upstream wall with respect to the length from the upstream wall to the downstream wall, such that the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(4.5) (dPa·sec) or more.
[3] A method for manufacturing a glass plate according to [1] or [2], wherein the glass ribbon is heated at a position 20% from the upstream wall with respect to the length from the upstream wall to the downstream wall, such that the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(6.0) (dPa·sec) or less.
[4] A method for manufacturing a glass plate according to any one of [1] to [3], wherein, at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, the difference between the temperature of the center of the glass ribbon in the width direction on the molten metal surface and the temperature of both ends of the molten metal in the width direction is 62°C or less.
[5] A method for manufacturing a glass plate according to any one of [1] to [4], wherein the glass ribbon is heated at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, such that the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(4.7) (dPa·sec) or more.
[6] A method for manufacturing a glass plate according to any one of [1] to [5], wherein the glass ribbon is heated at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, such that the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(6.3) (dPa·sec) or less.
[7] A method for manufacturing a glass plate according to any one of [1] to [6], wherein the ratio of the maximum width in the width direction of the glass ribbon in the molten metal bath to the length in the width direction of the glass ribbon at the downstream end of the molten metal bath is 1.4 to 2.2.
[8] A method for manufacturing a glass plate according to any one of [1] to [7], wherein the ratio a/b of the width a of the glass ribbon at a position 35% from the upstream wall to the length from the upstream wall to the downstream wall, and the length b of the glass ribbon in the width direction at the downstream end of the molten metal bath is 1.0 to 1.9.
[9] A method for manufacturing a glass plate according to any one of [1] to [8], wherein, with respect to the length from the upstream wall to the downstream wall, at a position 20% from the upstream wall, the ratio A/B of the widthwise length A of the glass ribbon to the widthwise length B of the molten metal surface not covered by the glass ribbon is 4 to 11.
[10] A method for producing wedge-shaped glass, comprising cutting a plate glass obtained by the plate glass production method described in any of [1] to [9].
[11] The wedge-shaped glass has at least one main surface that is convex,
A method for manufacturing a wedge-shaped glass according to [10], wherein, on a line segment that passes through the centroid G of the convex surface and connects two opposite sides of the four sides of the convex surface by the shortest distance, the point at which the wedge-shaped glass intersects with the sides of the convex surface is the point where the thickness of the wedge-shaped glass in the vertical direction is smaller when the wedge-shaped glass is placed on a horizontal surface is designated as the first point, and the point on the convex surface located at a distance of 2/5 of the length of the line segment from the first point is designated as the second point, and the angle between the line line connecting the first point and the second point and the horizontal plane is 0.020° to 0.050°.
[12] The method for manufacturing wedge-shaped glass according to [10] or [11], wherein the ratio T/M of the maximum thickness T to the minimum thickness M of the wedge-shaped glass is 1.10 to 1.40.
[13] Cut the plate glass obtained by the plate glass manufacturing method described in any of [1] to [9] to obtain wedge-shaped glass.
The aforementioned wedge-shaped glass and other plate glass are laminated and pressed together with an interlayer in between.
A method for manufacturing laminated glass.
[14] The other glass plate is the wedge-shaped glass,
[13] The method for manufacturing laminated glass.
[15] The other glass plate is a glass plate of a constant thickness.
[14] The method for manufacturing laminated glass.

A method for manufacturing flat glass can be provided that can suppress the reciprocating movement of the glass ribbon in the width direction. Furthermore, a method for manufacturing wedge-shaped glass and laminated glass can be provided that can suppress variations in the wedge angle of the wedge-shaped glass obtained by cutting the flat glass.

Figure 1(A) is a view of the glass manufacturing apparatus from the width direction, and Figure 1(B) is a view of the glass manufacturing apparatus from the thickness direction. Figure 2(A) is a cross-sectional view in the width direction of glass manufactured by a manufacturing method according to one embodiment of the present invention, and Figure 2(B) is a wedge-shaped glass obtained by cutting off portion A of the glass in Figure 2(A). Figure 3(A) is a plan view of the windshield, Figure 3(B) is a cross-sectional view of the windshield from Figure 3(A) along line B-B, and Figure 3(C) is a cross-sectional view of the windshield from Figure 3(A) along line C-C. Figure 4 is a magnified view of the top roll. Figures 5(A) and 5(B) show a plate glass according to one embodiment of the present invention, where Figure 5(A) is a plan view and Figure 5(B) is a cross-sectional view in the width direction.

The following describes one embodiment of the present invention. First, the configuration of the glass manufacturing apparatus (i.e., the float glass manufacturing apparatus) will be described.

As shown in Figures 1(A) and (B), the glass manufacturing apparatus 1 comprises a melting section 10, a molding section 20, and an annealing section 30. In the figures, the X direction is the direction of travel of the glass ribbon G2, where X1 is the upstream direction of the glass ribbon G2 and X2 is the downstream direction of the glass ribbon G2. In the figures, the Y direction is perpendicular to the direction of travel X of the glass ribbon G2 and is the width direction of the glass ribbon G2. In the figures, the Z direction is perpendicular to the direction of travel X and the width direction Y of the glass ribbon G2 (i.e., the thickness direction of the glass ribbon G2), where Z1 is upward and Z2 is downward. Figure 1(A) is a view of the glass manufacturing apparatus 1 from the width direction Y, and Figure 1(B) is a view of the glass manufacturing apparatus 1 from the thickness direction Z.

The melting section 10 comprises a melting furnace 11, a twill 12, and a lip 13. In the melting section 10, the glass raw material is melted into molten glass G1 in the melting furnace 11, and the amount of molten glass G1 supplied to the molding section 20 is adjusted by moving the twill 12 in the vertical direction Z relative to the lip 13, which is the flow path for the molten glass G1.

The molding unit 20 comprises a molten metal bath (float bath) 21, molten metal 22 stored in the molten metal bath 21, a plurality of top rolls 23, and a heater 24. In the molding unit 20, molten glass G1 continuously supplied from the melting unit 10 is gradually cooled while flowing in the direction of travel X, and formed into a glass ribbon G2. That is, the molten glass G1 is poured out in the shape of a glass ribbon onto the molten metal surface of the molten metal bath 21 (on the surface of the molten metal 22), and is propelled forward in the direction of travel X (downstream direction X2) while floating on the molten metal surface to be formed into a glass ribbon G2.

A molten metal bath 21 contains molten metal 22, such as tin. Molten glass G1 is continuously supplied onto the surface of the molten metal 22 via the twill 12 and lip 13.

The molten metal bath 21 has an upstream wall 25 located on the upstream side, a downstream wall 26 located on the downstream side, and two side walls 27, 27 connecting the upstream wall 25 and the downstream wall 26. Each of the two side walls 27, 27 is provided with a shoulder 27A that reduces the width of the molten metal bath 21 (dimension in the width direction Y) in the direction of travel X of the glass ribbon G2. That is, the side wall 27 has a first wall 27B connected to the upstream wall 25 and extending linearly in the downstream direction X2, a shoulder 27A connected to the first wall 27B and extending inward in the width direction Y (in the direction approaching the glass ribbon G2) as it moves downstream X2, and a second wall 27C connected to the shoulder 27A and extending linearly in the downstream direction X2. By providing the shoulder 27A in this way, the amount of molten metal 22 stored in the molten metal bath 21 is reduced.

The ratio W/N of the distance W between the two side walls 27, 27 upstream of the shoulder 27A of the molten metal bath 21 (distance between the two first walls 27B, 27B) and the distance N between the two side walls 27, 27 downstream of the shoulder 27A of the molten metal bath 21 (distance between the two second walls 27C, 27C) is set to be greater than 1.0 and less than or equal to 1.6 (1.0 < W/N ≤ 1.6). When manufacturing convex glass, it is necessary to make the glass ribbon G2 have a convex cross-section upstream of the molten metal bath 21 and to make the width of the glass ribbon G2 smaller than when manufacturing a glass plate of constant thickness. Therefore, the area of the molten metal 22 upstream of the shoulder 27A that is not covered by the glass ribbon G2 tends to increase, and thus reciprocating motion (swinging) of the glass ribbon G2 in the width direction Y is more likely to occur than when manufacturing a glass plate of constant thickness. If the W/N ratio is 1.6 or less, the area of the molten metal 22 not covered by the glass ribbon G2 upstream of the shoulder 27A is reduced, making it less likely for the molten metal 22 to flow upstream X1, which particularly affects the reciprocating motion (swing) of the glass ribbon G2, and also making it less likely for the glass ribbon G2 to reciprocate (swing) in the width direction Y when manufacturing wedge glass. If the W/N ratio is greater than 1.0, the distance between the two side walls 27, 27 downstream of the shoulder 27A can be narrowed, and the amount of molten metal 22 in the molten metal bath 21 can be reduced.

The position where the first wall 27B and the shoulder 27A are connected is preferably 60% to 75% of the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), which is 0.60L to 0.75L downstream in the X2 direction from the upstream wall 25. If the position where the first wall 27B and the shoulder 27A are connected is 60% to 75% of the upstream wall 25, the area of the molten metal 22 upstream of the shoulder 27A that is not covered by the glass ribbon G2 will not become too large when manufacturing wedge glass, and a sufficient molding area for the glass ribbon can be secured even when manufacturing glass of a constant thickness. The position where the first wall 27B and the shoulder 27A are connected is preferably 60% or more of the upstream wall 25, and more preferably 62% or more. The position where the first wall 27B and the shoulder 27A are connected is preferably 75% or less from the upstream wall 25, more preferably 70% or less, even more preferably 67% or less, and particularly preferably 65% or less.

The position where the shoulder 27A and the second wall 27C are connected is preferably 65% to 85% of the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), at a position 0.65L to 0.85L downstream X2 from the upstream wall 25. If the position where the shoulder 27A and the second wall 27C are connected is 65% to 85% of the upstream wall 25, the area of the molten metal 22 upstream of the shoulder 27A that is not covered by the glass ribbon G2 will not become too large when manufacturing wedge glass. Also, a sufficient molding area can be secured when manufacturing glass of a constant thickness. The position where the shoulder 27A and the second wall 27C are connected is preferably 65% or more from the upstream wall 25, and more preferably 67% or more. The position where the shoulder 27A and the second wall 27C are connected is preferably 85% or less from the upstream wall 25, more preferably 80% or less, even more preferably 76% or less, and particularly preferably 70% or less.

Multiple top rolls 23 rest on the upper surfaces of both ends G2B, G2B in the width direction of the glass ribbon G2. That is, the multiple top rolls 23 are in contact with both ends G2B, G2B in the width direction of the glass ribbon G2. The peripheral speed of each top roll 23 is adjusted to control the thickness of the glass ribbon G2.

The heater 24 is positioned above Z1 of the molten metal bath 21. The heater 24 is divided into, for example, a central heater 24A that heats the central part G2A in the width direction of the glass ribbon G2, and a pair of end heaters 24B, 24B that heat the width ends G2B, G2B of the glass ribbon G2 in the width direction. The central heater 24A and/or the end heaters 24B may be further divided in the direction of travel X and/or the width direction Y, in which case the temperature of the glass ribbon G2 can be easily adjusted. In the illustrated example, two heaters 24 are positioned in the direction of travel X, divided into an area upstream of the shoulder 27A and a region including the shoulder 27A and an area downstream of the shoulder 27A. The width of the downstream heater 24 is set shorter than the width of the upstream heater 24 according to the relationship between the distance W and the distance N.

The annealing section 30 comprises an annealing chamber 31 and a conveying roll 32. In the annealing section 30, the glass ribbon G2 formed in the molding section 20 is continuously conveyed and annealed by the conveying roll 32 located in the annealing chamber 31. Furthermore, the speed at which the glass ribbon G2 moves between the molding section 20 and the annealing section 30 can be adjusted by adjusting the peripheral speed of the conveying roll 32. Here, because the top roll 23 rested on the upper surfaces of both ends G2B, G2B in the width direction of the glass ribbon G2 in the molding section 20, distortion occurs near the parts of both ends G2B, G2B in the width direction of the glass ribbon G2 where the top roll 23 rested. The glass ribbon G2 is pulled out from the annealing section 30, and both ends of the glass ribbon G2 that have been distorted by the top roll 23 are cut and removed by a cutting machine. Furthermore, the glass ribbon G2 is cut to a predetermined size by the cutting machine to obtain the glass product.

Next, we will describe the glass produced by the manufacturing method according to one embodiment of the present invention (i.e., the float glass manufacturing method).

Figure 2(A) is a cross-sectional view in the width direction of glass manufactured by the manufacturing method according to one embodiment of the present invention, and Figure 2(B) is a wedge-shaped glass obtained by cutting off portion A of the glass in Figure 2(A). Figure 3(A) is a plan view of a windshield using glass manufactured by the manufacturing method according to one embodiment of the present invention, Figure 3(B) is a cross-sectional view of the windshield in Figure 3(A) along the line B-B, and Figure 3(C) is a cross-sectional view of the windshield in Figure 3(A) along the line C-C.

The plate glass manufactured by the manufacturing method according to one embodiment of the present invention is a convex glass 100 that becomes thicker from both ends toward the center in the width direction Y, as shown in Figure 2(A). By cutting this convex glass 100 at a predetermined position (for example, part A in Figure 2(A)), a wedge-shaped glass 200 can be obtained in which one end is thicker than the other end in the width direction Y, as shown in Figure 2(B). According to the manufacturing method of the present invention, the reciprocating movement (swing) of the glass ribbon G2 in the width direction Y can be suppressed, so that the variation in the wedge angle β of the wedge-shaped glass 200 obtained by cutting the convex glass 100 (plate glass) formed from the glass ribbon G2 can be suppressed. Here, the convex glass 100 only needs to become thicker from both ends toward the center in the width direction Y, and both sides may be convex, or one surface may be flat and the other surface may be convex.

The wedge-shaped glass 200 is preferably used in the windshields 300 and 400 of automobiles equipped with a HUD, as shown in Figures 3(A) to (C). By using the wedge-shaped glass 200 in the windshields 300 and 400 in this way, the occurrence of double images as seen by the driver can be suppressed without using a special interlayer (for example, an interlayer with a wedge-shaped cross-section).

The wedge-shaped glass 200 is not limited to automobile windshields; it can also be used as train windows, windshields for motorcycle riders, or any other type of glass that can display information. Furthermore, the wedge-shaped glass 200 is not limited to information display glass in vehicles; it can be used in various other types of information display glass. In addition, it can be used in various devices that utilize continuous changes in transmission characteristics, even for applications other than information display.

Furthermore, the windshield 300 shown in Figure 3(B) is a laminated glass manufactured by laminating and pressing together wedge-shaped glass 301 and wedge-shaped glass 302 with an interlayer 303 sandwiched in between.

As another form of windshield, one of the two panes of glass to be joined may be of uniform thickness. As shown in Figure 3(C), the windshield 400 is a laminated glass manufactured by laminating and pressing together a wedge-shaped glass 401 and a glass of uniform thickness 402 with an interlayer 403 in between.

Next, a method for manufacturing flat glass according to one embodiment of the present invention will be described.
In a method for manufacturing flat glass according to one embodiment of the present invention, when manufacturing a convex glass 100 in which the cross-section in the width direction Y perpendicular to the direction of travel X of the glass ribbon is convex, the glass ribbon G2 formed by continuously supplying molten glass G1, which is melted in the melting section 10, onto the molten metal 22 is heated more strongly at both ends G2B, G2B in the width direction than at the center G2A in the width direction in the upstream area of the molten metal bath 21. By heating both ends G2B, G2B in the width direction of the glass ribbon G2 more strongly than at the center G2A in the width direction, the viscosity of both ends G2B, G2B in the width direction of the glass ribbon G2 does not increase as easily as at the center G2A in the width direction. As a result, the thickness of both ends G2B, G2B in the width direction of the glass ribbon G2 tends to be thinner, and the thickness of the center G2A in the width direction tends to be thicker.

Furthermore, when manufacturing convex glass in the conventional float glass manufacturing apparatus 1 described above, it is preferable to heat the molten metal bath 21 using only the end heaters 24B located at both ends in the width direction, without substantially using the central heater 24A located in the center in the width direction in the upstream area. Here, "upstream area" refers to the 70% upstream area of the molten metal bath 21 that is close to the melting furnace 11. Also, "not substantially using the central heater 24A" means that the output of the central heater 24A is less than 1 kW/ ^m² . By substantially not using the central heater 24A and heating only with the end heaters 24B, the viscosity of the glass ribbon at both ends G2B, G2B in the width direction does not increase as much as the central part G2A in the width direction, resulting in thinner glass ribbons at both ends G2B, G2B in the width direction and thicker central part G2A in the width direction. The output of the central heater 24A may be 0 kW/ ^m² . Also, the central part G2A in the width direction may be cooled.

In the "downstream region," which is the 30% of the molten metal bath 21 closest to the slow-cooling chamber 31, the central part G2A in the width direction of the glass ribbon may be heated by the central heater 24A.

Furthermore, it is preferable to heat the glass ribbon G2 on the molten metal surface such that the cooling rate at both ends G2B, G2B in the width direction is 6.1°C/m or less. Here, "cooling rate" refers to the amount of temperature decrease when the glass ribbon G2 moves 1 m in the direction of travel X in the molten metal bath 21. If the cooling rate at both ends G2B, G2B in the width direction of the glass ribbon G2 is 6.1°C/m or less, the viscosity at both ends G2B, G2B in the width direction will not increase easily, the ends G2B, G2B in the width direction will be thin, and the central part G2A in the width direction will be thicker. It is more preferable that the cooling rate at both ends G2B, G2B in the width direction is 6.0°C/m or less, and even more preferable that it is 5.9°C/m or less. In this specification, when the cooling rate at the ends of the glass ribbon G2 in the width direction is indicated, the ends refer to a position 50 mm from the end of the glass ribbon G2 towards the center in the width direction.

On the other hand, it is preferable to heat the glass ribbon G2 so that the cooling rate of both ends G2B, G2B in the width direction is 3.0°C/m or higher. If the cooling rate of both ends G2B, G2B in the width direction is 3.0°C/m or higher, the glass ribbon G2 will cool down sufficiently. The cooling rate of both ends G2B, G2B in the width direction may be 4.0°C/m or higher, or 5.0°C/m or higher.

The cooling rate of the ends G2B, G2B in the width direction of the glass ribbon G2 is preferably slower than the cooling rate of the central part G2A in the width direction of the glass ribbon G2. If the cooling rate of the ends G2B, G2B in the width direction is slower than the cooling rate of the central part G2A in the width direction, the viscosity of the ends will not increase easily, and the ends G2B, G2B in the width direction will be thinner, while the central part G2A in the width direction will be thicker.

The cooling rate of the ends G2B, G2B in the width direction of the glass ribbon G2 is preferably 0.3°C/m or more slower than the cooling rate of the central part G2A in the width direction of the glass ribbon G2. If it is 0.3°C/m or more slower, the viscosity of the ends G2B, G2B in the width direction will not increase easily, and the ends G2B, G2B in the width direction will be thinner, while the central part G2A in the width direction will be thicker. The cooling rate of the ends G2B, G2B in the width direction may be 0.4°C/m or more slower than the cooling rate of the central part G2A in the width direction, and may also be 0.5°C/m or more slower.

Furthermore, it is preferable to control the heating temperature of the glass ribbon G2B, G2B at both ends G2B, G2B in the width direction on the molten metal surface so that the distance between the position where the viscosity of the glass ribbon G2B at both ends G2B, G2B is ^104.9 (dPa・sec) and the position where the viscosity is ^106.1 (dPa・sec) is 15 m or more. If the distance is 15 m or more, the viscosity of the glass ribbon G2B, G2B at both ends G2B, G2B in the width direction does not increase easily, the glass ribbon G2B, G2B at both ends G2B, G2B in the width direction tends to be thin, and the central part G2A in the width direction tends to be thick. The aforementioned distance is more preferably 16 m or more, and even more preferably 16.5 m or more. Here, the viscosity of the glass ribbon G2 is calculated by measuring the temperature of the glass ribbon G2 with a radiation thermometer and using the glass viscosity curve (Fulcher formula) from the measured temperature. In this specification, when describing the viscosity of the end of the glass ribbon G2 in the width direction, as described above, the end refers to a position 50 mm from the end of the glass ribbon G2 towards the center in the width direction.

On the other hand, it is preferable to control the heating temperature of the widthwise ends G2B, G2B of the glass ribbon G2 on the molten metal surface such that the distance between the position where the viscosity of the widthwise ends G2B, G2B is ^104.9 (dPa・sec) and the position where the viscosity is ^106.1 (dPa・sec) is 30 m or less. If the distance is 30 m or less, the glass ribbon can be cooled sufficiently. The aforementioned distance may be 25 m or less, or 20 m or less.

Furthermore, a top roll 23 is placed on the upper surface of both ends G2B, G2B in the width direction of the glass ribbon G2 heated by the heater 24, and the glass ribbon is shaped to the desired width, thickness, and shape by the action of this top roll 23. At this time, it is preferable that the peripheral speed of each top roll 23 is adjusted so that the one located downstream is faster. Also, when manufacturing the convex glass 100, it is preferable to rotate the multiple top rolls 23 such that the peripheral speed of the top roll 23A upstream in the direction of travel X of the glass ribbon G2 is slower than the peripheral speed of the top roll 23B downstream. In addition, by substantially not using the central heater 24A and heating only with the end heaters 24B, the viscosity of both ends G2B, G2B in the width direction of the glass ribbon does not increase as easily as the central part G2A in the width direction. As a result, when widening the width of the glass ribbon G2 that spreads out on both sides of the rotation axis of the upstream top roll 23A, the ends G2B, G2B in the width direction of the glass ribbon G2 can be made thinner, and the central part G2A in the width direction can be made thicker.

The upstream top roll 23A refers to the top roll 23 closest to the melting furnace 11 among the multiple pairs of top rolls 23 arranged at both ends G2B, G2B in the width direction of the glass ribbon G2 advancing in the molten metal bath 21. It may be just one pair closest to the melting furnace 11, or two pairs or three pairs close to the melting furnace 11. Preferably, there are two pairs. In particular, the pair of top rolls 23 closest to the melting furnace 11 is called the upstream top roll 23A. The downstream top roll 23B refers to the top roll 23 closest to the annealing chamber 31. It may be just one pair closest to the annealing chamber 31, or two pairs or three pairs close to the annealing chamber 31. In particular, the pair of top rolls 23 closest to the annealing chamber 31 is called the downstream top roll 23B. Figures 1(A) and (B) illustrate an example where there are two pairs of upstream top rolls 23A and two pairs of downstream top rolls 23B.

It is preferable to arrange 7 to 15 pairs of top rolls 23 at both ends G2B, G2B in the width direction of the glass ribbon G2. Having 7 to 15 pairs makes it easier to adjust the glass ribbon G2 to a predetermined thickness. It is more preferable to arrange 8 to 13 pairs of top rolls 23. Figures 1(A) and (B) illustrate an example where 9 pairs of top rolls 23 are arranged at both ends G2B, G2B in the width direction of the glass ribbon G2.

Furthermore, in the region where the viscosity of the widthwise ends G2B, G2B of the glass ribbon G2 on the molten metal surface is ^105.3 (dPa・sec) or less (hereinafter referred to as the low viscosity region), the number of top rolls 23 arranged at the widthwise ends G2B, G2B may be 8 pairs or less, 7 pairs or less, 6 pairs or less, 5 rolls or less, or 3 pairs or less.

On the other hand, in the region where the viscosity of the widthwise ends G2B, G2B of the glass ribbon G2 on the molten metal surface is greater than ^105.3 (dPa·sec) (hereinafter referred to as the high viscosity region), the number of top rolls 23 arranged at the widthwise ends G2B, G2B may be 10 pairs or less, 8 pairs or less, 6 pairs or less, 4 rolls or less, 2 pairs or less, or 1 pair or less.

The upstream top roll 23A may be positioned in the low viscosity region, and the downstream top roll 23B may be positioned in the high viscosity region.

In a top roll 23 positioned in a region (low viscosity region) where the viscosity of the widthwise ends G2B, G2B of the glass ribbon G2 on the molten metal surface is ^105.3 (dPa・sec) or less, it is preferable that the difference in peripheral speed of at least one pair of adjacent top rolls 23, 23 in the direction of travel X is 35 (m/hour) or more. If it is 35 (m/hour) or more, in the region where the viscosity of the glass ribbon G2 is ^105.3 (dPa・sec) or less, the glass ribbon G2 is pulled downstream in X2, and the widthwise ends G2B, G2B can be thinned. As a result, the widthwise ends G2B, G2B are thinned and the widthwise center G2A is thickened, resulting in the production of a glass plate with a convex cross-section in the widthwise Y direction.

In the region where the viscosity of both ends G2B, G2B in the width direction of the glass ribbon G2 in the molten metal bath 21 is ^105.3 (dPa·sec) or less, the difference in peripheral speed of at least one pair of adjacent top rolls 23, 23 in the direction of travel X may be 40 (m/hour) or more, 45 (m/hour) or more, or 50 (m/hour) or more.

On the other hand, in a top roll 23 positioned in a region (low viscosity region) where the viscosity of both ends G2B, G2B in the width direction of the glass ribbon G2 on the molten metal surface is ^105.3 (dPa・sec) or less, it is preferable that the difference in peripheral speed of at least one pair of adjacent top rolls 23, 23 in the direction of travel X is 100 (m/hour) or less. If it is 100 (m/hour) or less, it is easy to adjust the thickness of the glass ribbon G2. It may also be 80 (m/hour) or less, or 60 (m/hour) or less.

The peripheral speed R of the uppermost top roll 23A is preferably 120 m/h or less. If it is 120 m/h or less, the width of the glass ribbon G2 extending to both sides of the rotation axis of the uppermost pair of top rolls 23A can be increased. As a result, the widthwise ends G2B, G2B of the glass ribbon G2 tend to be thin, while the widthwise central part G2A tends to be thicker. The peripheral speed R of the uppermost top roll 23A may be 110 m/h or less, 100 m/h or less, 90 m/h or less, 80 m/h or less, 70 m/h or less, or 60 m/h or less.

On the other hand, the peripheral speed R of the uppermost top roll 23A is preferably 30 m/hour or higher. A peripheral speed of 30 m/hour or higher makes it easier to adjust the thickness of the glass ribbon G2. The peripheral speed R of the uppermost top roll 23A may also be 40 m/hour or higher, or even 50 m/hour or higher.

Figure 4 is an enlarged view of the top roll 23. As shown in Figure 4, the angle D between the direction of travel X of the glass ribbon G2 and the rotation axis J of the top roll 23 may be adjusted to adjust the thickness of the glass ribbon G2. By adjusting the angle D of the uppermost top roll 23A to 75° to 90° and the angle D of the lowermost top roll 23B to 90° to 105°, it is easier to reduce the thickness of the widthwise ends G2B, G2B of the glass ribbon G2. The angle D of the uppermost top roll 23A is more preferably 80° to 85°, and even more preferably 81° to 84°. The angle D of the lowermost top roll 23B is more preferably 95° to 100°, and even more preferably 96° to 99°.

Furthermore, by adjusting the advance speed of the glass ribbon G2 in the molding section 20 and the slow cooling section 30, it becomes easier to spread the glass ribbon G2 in the width direction Y upstream of the molten metal bath 21, and the thickness of both ends G2B, G2B in the width direction of the glass ribbon G2 can be reduced.

The advance speed of the glass ribbon G2 in the molding section 20 and the annealing section 30 may be 200 to 1500 m/hours. Setting the advance speed of the glass ribbon G2 in the molding section 20 and the annealing section 30 to 200 to 1500 m/hours makes it easier to spread the glass ribbon G2 in the width direction Y upstream of the molten metal bath 21, and makes it easier to reduce the thickness of the widthwise ends G2B, G2B of the glass ribbon G2. The advance speed of the glass ribbon G2 may be 500 m/hours or more, 600 m/hours or more, or 700 m/hours or more. On the other hand, the advance speed of the glass ribbon G2 may be 1300 m/hours or less, 1100 m/hours or less, or 900 m/hours or less.

The difference (T-M) between the maximum value T and the minimum value M of the thickness of the plate glass manufactured by the manufacturing method according to one embodiment of the present invention is preferably 0.1 mm or more. If the difference (T-M) is 0.1 mm or more, the occurrence of double images can be reduced when used as information display glass, even when installed in a vehicle with a large angle of the windshield to the horizontal plane. Here, the difference (T-M) between the maximum value T and the minimum value M of the thickness of the plate glass is the difference between the maximum and minimum values of the thickness of the convex glass 100 obtained by cutting and removing both ends in the width direction Y of the glass ribbon G2, which is distorted by the top roll 23, using a cutting machine. The difference (T-M) may be 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, or 0.5 mm or more. On the other hand, the difference (T-M) may be 1.5 mm or less. If it is 1.5 mm or less, distortion of the reflected image can be suppressed when used as information display glass, even when installed in a vehicle with a small angle of the windshield to the horizontal plane. The difference (T-M) may be 1.3 mm or less, 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less. When this glass plate is used, for example, as a windshield for an automobile, the optimal difference (T-M) between the maximum value T and the minimum value M of the glass plate thickness is selected depending on the angle at which the windshield is installed and the angle and position of the illuminator for displaying information.

In the plate glass manufactured by the manufacturing method according to one embodiment of the present invention, it is preferable that the maximum height Rz of the roughness curve at a standard length of 25 mm as specified in JIS B 0601:2001 on the main surface of the plate glass is 0.3 μm or less. If the Rz of the main surface of the plate glass is 0.3 μm or less, for example, when the plate glass is used as information display glass, the scenery viewed through the glass will appear without distortion. Also, the reflected image when information is displayed on the plate glass will be less likely to be distorted. Here, the roughness curve is represented by a shape waveform. Rz is more preferably 0.25 μm or less, even more preferably 0.2 μm or less, particularly preferably 0.18 μm or less, and most preferably 0.16 μm or less. The Rz of the main surface of the plate glass can be reduced by slowing down the advance speed V of the glass ribbon G2 in the annealing section 30. Here, the main surface of the glass plate refers to the surface in the molten metal bath 21 that was in contact with the molten metal 22 (hereinafter referred to as the molten metal contact surface), and the surface opposite the molten metal contact surface that was not in contact with the molten metal 22 (hereinafter referred to as the molten metal non-contact surface).

As shown in Figure 1(B), the ratio W/N of the distance W between the two side walls 27, 27 upstream of the shoulder 27A of the molten metal bath 21 (distance between the two first walls 27B, 27B) and the distance N between the two side walls 27, 27 downstream of the shoulder 27A of the molten metal bath 21 (distance between the two second walls 27C, 27C) is preferably greater than 1.0 and less than or equal to 1.6 (1.0 < W/N ≤ 1.6). If W/N is 1.6 or less, the area of the portion of the molten metal 22 upstream of the shoulder 27A that is not covered by the glass ribbon G2 decreases, making it less likely for the molten metal 22 to flow upstream X1, and less likely for the glass ribbon G2 to reciprocate (swing) in the width direction Y. Therefore, variations in the wedge angle β of the wedge-shaped glass 200 (see Figure 2(B)) obtained by cutting the convex glass 100 (see Figure 2(A)) obtained by the manufacturing method of plate glass of this embodiment can be suppressed.

If the W/N ratio is greater than 1.0, the distance between the two side walls 27, 27 downstream of shoulder 27A can be narrowed, and the amount of molten metal 22 in the molten metal bath 21 can be reduced.

The W/N ratio is more preferably 1.1 or higher, and even more preferably 1.3 or higher. Furthermore, the W/N ratio is more preferably 1.55 or lower, and even more preferably 1.50 or lower.

It is preferable that the glass ribbon G2 is heated by the heater 24 such that, at a position 20% from the upstream wall 25 (0.2L downstream X2 from the upstream wall 25) with respect to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), the viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface is 10^(4.5) (dPa·sec) or more. If the viscosity of the central part G2A in the width direction is 10^(4.5) (dPa·sec) or more, the ends G2B, G2B in the width direction tend to be thin, and the central part G2A in the width direction tends to be thick. Therefore, the wedge angle β of the wedge-shaped glass 200 (see Figure 2(B)) obtained by cutting the convex glass 100 (see Figure 2(A)) obtained by the manufacturing method of plate glass of this embodiment can be increased.

The viscosity of the central portion G2A of the glass ribbon G2 in the width direction on the molten metal surface at a position 20% from the upstream wall 25 (0.2L downstream X2 from the upstream wall 25) is more preferably 10^(5.0) (dPa·sec) or higher, and even more preferably 10^(5.3) (dPa·sec) or higher. This is because the temperature of the central portion G2A in the width direction of the glass ribbon G2 is relatively lower than the temperatures of the ends G2B, G2B in the width direction, allowing the wedge angle β to be increased.

It is preferable that the glass ribbon G2 is heated by the heater 24 such that, at a position 20% from the upstream wall 25 (0.2L downstream X2 from the upstream wall 25) with respect to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), the viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface is 10^(6.0) (dPa·sec) or less. If the viscosity of the glass ribbon G2 is too high, the top roll 23 will have difficulty entering the glass ribbon G2, making it difficult to control the position of the glass ribbon G2, and thus reciprocating motion (swing) in the width direction will easily occur. In this embodiment, since the viscosity of the central part G2A in the width direction is 10^(6.0) (dPa·sec) or less, the occurrence of swing can be suppressed.

The viscosity of the central portion G2A of the glass ribbon G2 in the width direction on the molten metal surface at a position 20% from the upstream wall 25 (0.2L downstream X2 from the upstream wall 25) is more preferably 10^(5.8) (dPa·sec) or less, and even more preferably 10^(5.6) (dPa·sec) or less. This is because the lower the viscosity of the glass ribbon G2, the easier it is for the top roll 23 to enter the glass ribbon G2, thereby suppressing the occurrence of swing.

It is preferable that the temperature difference (I-K) between the temperature I of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface and the temperature K of both ends in the width direction of the molten metal 22 at a position 32% from the upstream wall 25 (0.32L downstream from the upstream wall 25 in the X2 direction) is 62°C or less. If the temperature difference (I-K) is 62°C or less, the difference in viscosity between both ends and the central part in the width direction of the glass ribbon G2 becomes small, and the ends G2B, G2B in the width direction tend to be thin, while the central part G2A in the width direction tends to be thick. The temperature difference (I-K) is more preferably 50°C or less, and even more preferably 40°C or less. The lower limit of the temperature difference (I-K) may be 0°C or higher, 10°C or higher, or 15°C or higher in order to suppress excessive output to the heater 24. Note that the temperature K at both ends of the molten metal 22 in the width direction refers to the temperature at a position 50 mm from the center in the width direction from each of the two side walls 27, 27 of the molten metal bath 21.

It is preferable that the glass ribbon G2 is heated by the heater 24 such that, at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) with respect to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), the viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface is 10^(4.7) (dPa·sec) or more. If the viscosity of the central part G2A in the width direction is 10^(4.7) (dPa·sec) or more, the ends G2B, G2B in the width direction tend to be thin, and the central part G2A in the width direction tends to be thick. Therefore, the wedge angle β of the wedge-shaped glass 200 (see Figure 2(B)) obtained by cutting the convex glass 100 (see Figure 2(A)) obtained by the manufacturing method of plate glass of this embodiment can be increased.

The viscosity of the central portion G2A of the glass ribbon G2 in the width direction on the molten metal surface at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) is more preferably 10^(5.0) (dPa·sec) or higher, and even more preferably 10^(5.3) (dPa·sec) or higher. This is because the temperature of the central portion G2A of the glass ribbon G2 in the width direction is lower than the temperatures of the ends G2B, G2B in the width direction, allowing the wedge angle β to be increased.

It is preferable that the glass ribbon G2 is heated by the heater 24 such that, at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) with respect to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), the viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface is 10^(6.3) (dPa·sec) or less. If the viscosity of the glass ribbon G2 is too high, the top roll 23 will have difficulty entering the glass ribbon G2, making it difficult to control the position of the glass ribbon G2, and thus reciprocating motion (swing) in the width direction will easily occur. In this embodiment, since the viscosity of the central part G2A in the width direction is 10^(6.3) (dPa·sec) or less, the occurrence of swing can be suppressed.

The viscosity of the central portion G2A of the glass ribbon G2 in the width direction on the molten metal surface at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) is more preferably 10^(6.0) (dPa·sec) or less, and even more preferably 10^(5.8) (dPa·sec) or less. This is because the lower the viscosity of the glass ribbon G2, the easier it is for the top roll 23 to enter the glass ribbon G2, thereby suppressing the occurrence of swing.

Preferably, the ratio c/b of the maximum width c of the glass ribbon G2 in the width direction Y (located between the upstream wall 25 and the downstream wall 26) and the length b of the glass ribbon G2 in the width direction Y at the downstream end of the molten metal bath 21 is 1.4 to 2.2 (1.4 ≤ c/b ≤ 2.2). If the ratio c/b is 1.4 to 2.2, the area of the molten metal 22 that is not covered by the glass ribbon G2 decreases, making it difficult for the molten metal 22 to flow upstream X1, and making it difficult for the glass ribbon G2 to reciprocate (swing) in the width direction Y.

Furthermore, the ratio c/b is more preferably 1.6 or higher, and even more preferably 1.7 or higher. The ratio c/b is more preferably 2.1 or lower, and even more preferably 2.0 or lower. The widthwise length of the glass ribbon G2 in the molten metal bath 21 is determined from the image obtained by photographing the glass ribbon G2 with a camera and the position of the top roll.

With respect to the length L from the upstream wall 25 to the downstream wall 26, the ratio a/b of the width a (not shown) of the glass ribbon G2 at a position 35% from the upstream wall 25 (0.35L downstream from the upstream wall 25 in the X2 direction) and the length b (not shown) of the glass ribbon G2 in the width direction Y at the downstreammost point of the molten metal bath 21 is preferably 1.0 to 1.9 (1.0 ≤ a/b ≤ 1.9). If the ratio a/b is 1.0 to 1.9, the area of the molten metal 22 that is not covered by the glass ribbon G2 decreases, making it difficult for the molten metal 22 to flow upstream in the X1 direction, and making it difficult for the glass ribbon G2 to reciprocate (swing) in the width direction Y.

Furthermore, the ratio a/b is more preferably 1.3 or higher, and even more preferably 1.4 or higher. The ratio a/b is more preferably 1.8 or lower, even more preferably 1.7 or lower, and particularly preferably 1.6 or lower.

With respect to the length L from the upstream wall 25 to the downstream wall 26, it is preferable that the ratio A/B of the length A (not shown) in the width direction Y of the glass ribbon G2 to the length B (not shown) in the width direction Y of the molten metal surface not covered by the glass ribbon G2 is between 4 and 11 (4 ≤ A/B ≤ 11). Length B is the length in the width direction Y of the molten metal on both sides of the glass ribbon G2 at the 20% position from the upstream wall 25 (0.2L in the downstream direction X2 from the upstream wall 25). Therefore, length B is obtained by subtracting length A from the distance W (see Figure 1(B)) between the two side walls 27, 27 in the upstream region of the shoulder 27A of the molten metal bath 21 (B = W - A). In this way, since the ratio A/B is set to 4 to 11, the molten metal 22 is covered by the glass ribbon G2 over a wide area, making it difficult for the molten metal 22 to flow upstream X1, and suppressing the reciprocating motion (swing) of the glass ribbon G2 in the width direction Y. The length B is determined from an image obtained by photographing the molten metal surface not covered by the glass ribbon G2 with a camera.

Furthermore, if the ratio A/B is less than 4, the exposed area of the molten metal 22 widens, making it easier for the glass ribbon G2 to swing. Also, if the ratio A/B is greater than 11, the width of the glass ribbon G2 widens relative to the molten metal bath 21, making it difficult to control the width of the glass ribbon G2 with the top roll 23, and making it easier for it to interfere with components installed in the molten metal bath 21. Therefore, it is preferable to keep the ratio A/B at 11 or less. Moreover, it is more preferable for the ratio A/B to be 5 or more, and even more preferable for it to be 5.5 or more. It is more preferable for the ratio A/B to be 10 or less, and even more preferable for it to be 9 or less.

Wedge-shaped glass and laminated glass are manufactured using the plate glass produced by the plate glass manufacturing method described above.
A method for manufacturing wedge-shaped glass and laminated glass according to one embodiment of the present invention will be described with reference to Figures 2(A) to (B) and 3(A) to (C). Here, a method for manufacturing laminated glass used in vehicle windshields will be used as an example.

A method for manufacturing wedge-shaped glass according to one embodiment of the present invention includes the step of cutting a convex-shaped plate glass 100 obtained by the plate glass manufacturing method described above to obtain wedge-shaped glass 200. A method for manufacturing laminated glass according to one embodiment of the present invention includes the step of cutting a convex-shaped plate glass 100 obtained by the plate glass manufacturing method described above to obtain wedge-shaped glass 200, and the step of laminating and pressing the wedge-shaped glass 200 and other plate glass with an interlayer film in between.

First, by the above-described method for manufacturing flat glass, a convex glass 100 is obtained that becomes thicker towards the center in the width direction (see Figure 2(A)). By cutting this convex glass 100 at a predetermined position (part A in the figure), a wedge-shaped glass 200 is obtained in which one end is thicker than the other end in the width direction (see Figure 2(B)). The cutting method is not limited, but for example, a scribe line in the shape of a window glass can be formed on the convex glass 100 with a cutter, and the convex glass 100 can be cut out by breaking it, thereby obtaining the wedge-shaped glass 200. The edges of the wedge-shaped glass 200 are then chamfered.

Next, the pair of wedge-shaped glass 200 and another sheet glass are bent by gravity bending or other methods while overlapping with a release agent in between. The pair of sheet glass is heated in a furnace, softened, bent, and then slowly cooled. Note that the bending method is not limited to gravity bending; the pair of sheet glass may be formed by press bending, or each sheet may be bent individually without overlapping.

Next, laminated glass is obtained by laminating the wedge-shaped glass 200 and other flat glass with an interlayer in between and pressing them together. The other flat glass may be the wedge-shaped glass 200 or a flat glass of uniform thickness. The flat glass of uniform thickness is obtained by a known method and cut by the cutting method described above. Laminated glass 300 in which the other flat glass is the wedge-shaped glass 200 (see Figures 3(A) and (B)) is installed in a vehicle with a large angle of the windshield to the horizontal plane, and the reflected image when displaying information is less distorted. Laminated glass 400 in which the other flat glass is a flat glass of uniform thickness (see Figure 3(C)) allows the view through the windshield to appear without distortion. As a material for the interlayer, polyvinyl butyral can be used as an example.

When bonding, the pair of glass plates and the interlayer are first degassed to remove air between them, and then heated to bond them together. For example, the air can be removed by placing the assembled pair of glass plates and the interlayer in a rubber bag and heating it under reduced pressure. Alternatively, the nipper-top roll method or the rubber channel method may be used. Next, the assembled pair of glass plates and the interlayer are subjected to pressure treatment in an autoclave to heat and bond them together. As the interlayer, for example, polyvinyl butyral (PVB) or ethylene vinyl acetate (EVA) can be used.

Next, we will describe a wedge-shaped glass according to one embodiment of the present invention.
Figures 5(A) and 5(B) show a wedge-shaped glass 500 according to one embodiment of the present invention, where Figure 5(A) is a plan view and Figure 5(B) is a cross-sectional view.

The wedge-shaped glass 500 according to one embodiment of the present invention can be obtained, for example, by cutting a plate glass obtained by the plate glass manufacturing method described above. The cutting method is not limited, but for example, the wedge-shaped glass 500 according to one embodiment of the present invention can be obtained by forming scribe lines in the shape of a window glass on the plate glass with a cutter and then breaking it.

When the wedge-shaped glass 500 according to one embodiment of the present invention is used as the windshield of a vehicle, the wedge-shaped glass 500 is installed in the vehicle such that, for example, the side 502 with the minimum thickness is located at the bottom, and information is displayed at the bottom where the windshield is thinner.

A wedge-shaped glass 500 according to one embodiment of the present invention is characterized in that at least one main surface is a convex surface 507. Because the main surface is a convex surface 507, the reflected image when information is displayed on the glass plate is less likely to be distorted. Furthermore, compared to the case where the main surface is concave, the thickness of the upper part of the windshield where no information is displayed is reduced, allowing for a reduction in the weight of the windshield and improving the vehicle's fuel efficiency. The position where information is displayed on the windshield is not limited to the lower part; it may be at the top, on the left or right, or in the center. The glass plate is installed so that the thickness of the area where information is displayed is reduced. In any case, if the main surface is a convex surface 507, the thickness of the portion where no information is displayed can be reduced compared to the case where the main surface is concave, thus reducing the weight of the windshield.

The wedge-shaped glass 500 according to one embodiment of the present invention is preferably rectangular. If the wedge-shaped glass 500 is rectangular, handling such as transportation is easy. Here, the term "rectangle" does not mean a perfect rectangle; the sides may be curved. Also, the angle of the corners is not limited to 90°; it may be between 80 and 100°.

The wedge-shaped glass 500 according to one embodiment of the present invention may have notches and its corners may be arc-shaped.

In one embodiment of the present invention, the wedge-shaped glass 500 passes through the centroid G of the convex surface 507 and connects two opposing sides of the four sides 501, 502, 508, and 509 of the convex surface 507 by the shortest distance. Of the intersection points 504 and 505 of the line segment 503 and the sides of the convex surface 507, the point where the thickness of the wedge-shaped glass 500 in the vertical direction is smaller when the wedge-shaped glass 500 is placed on a horizontal surface is designated as the first point 504. The point on the convex surface 507 located at a distance of 2/5 of the length of the line segment 503 from the first point 504 is designated as the second point 506. Preferably, the angle α between the straight line H connecting the first point 504 and the second point 506 and the horizontal plane is 0.020° to 0.050°. The thickness of the glass plate is determined, for example, by a laser displacement meter, microgauge, ultrasonic thickness gauge, etc., and the angle α is calculated from the measured thickness.

When the windshield is installed in a vehicle where the angle of the windshield with respect to the horizontal plane is small, a smaller angle α of the wedge-shaped glass 500 is preferable because it reduces the double image of the projected image projected onto the windshield. On the other hand, when the windshield is installed in a vehicle where the angle of the windshield with respect to the horizontal plane is large, a larger angle α of the wedge-shaped glass 500 is preferable because it reduces the double image of the projected image projected onto the windshield.

The wedge-shaped glass 500 according to one embodiment of the present invention reduces double images when information is displayed on a flat glass surface when mounted on a vehicle with a large angle of the windshield to the horizontal plane, by having an angle α of 0.020° or more. The angle α may also be 0.023° or more, 0.025° or more, 0.030° or more, or 0.033° or more. Furthermore, by having an angle α of 0.050° or less, double images are reduced when information is displayed on a flat glass surface even when mounted on a vehicle with a small angle of the windshield to the horizontal plane. The angle α may also be 0.04° or less. The optimal angle α is selected depending on the angle at which the windshield is mounted and the mounting angle and position of the illuminator for displaying information.

In one embodiment of the present invention, the wedge-shaped glass 500 preferably has a maximum height Rz of 0.3 μm or less of the roughness curve at a standard length of 25 mm as specified in JIS B 0601:2001 for the main surface of the wedge-shaped glass 500. Because Rz is 0.3 μm or less, the view seen through the wedge-shaped glass 500 appears without distortion. In addition, the reflected image when information is displayed on the glass plate is less likely to be distorted.

In one embodiment of the present invention, the wedge-shaped glass 500 preferably has a difference (T-M) between the maximum value T and the minimum value M of the thickness of the wedge-shaped glass 500 of 0.1 mm or more. Because the difference (T-M) between the maximum value T and the minimum value M of the thickness of the plate glass is 0.1 mm or more, the occurrence of double images can be suppressed when it is installed in a vehicle with a large angle of the windshield with respect to the horizontal plane and used as information display glass. On the other hand, the difference (T-M) may be 1.5 mm or less. If it is 1.5 mm or less, the occurrence of double images can be suppressed when it is installed in a vehicle with a small angle of the windshield with respect to the horizontal plane and used as information display glass. The difference (T-M) may be 1.3 mm or less, 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less.

In one embodiment of the present invention, the wedge-shaped glass 500 preferably has a ratio T/M of 1.10 to 1.40 between the maximum and minimum thickness T of the wedge-shaped glass 500. If T/M is 1.10 or higher, the occurrence of double images can be suppressed when the glass is mounted on a vehicle with a large angle of the windshield to the horizontal plane and information is displayed on the glass. The ratio T/M may be 1.12 or higher, 1.15 or higher, 1.20 or higher, or 1.25 or higher. Furthermore, if the ratio T/M is 1.40 or lower, the occurrence of reflected images can be suppressed when information is displayed on the glass, even when mounted on a vehicle with a small angle of the windshield to the horizontal plane. The ratio T/M may be 1.35 or lower, 1.30 or lower, or 1.28 or lower. The optimal ratio T/M is selected depending on the angle at which the windshield is mounted and the mounting angle and position of the illuminator for displaying information.

In one embodiment of the present invention, the wedge-shaped glass 500 preferably has short sides 508 and 509 of 600 mm or more. If it is 600 mm or more, it can be used in large vehicles. It can also be installed in vehicles where the angle of the windshield with respect to the horizontal plane is small. The plate glass may be 800 mm or more, 1000 mm or more, 1200 mm or more, or 1400 mm or more.

Laminated glass can be manufactured using wedge-shaped glass 500.
A method for manufacturing laminated glass according to one embodiment of the present invention includes the step of cutting a plate glass 100 to obtain wedge-shaped glass. A method for manufacturing laminated glass according to one embodiment of the present invention includes the step of cutting a plate glass 100 to obtain wedge-shaped glass, and the step of laminating and pressing the wedge-shaped glass and other plate glass with an interlayer in between.

First, by cutting the plate glass 100 at a predetermined position, a wedge-shaped glass is obtained in which one end is thicker than the other in the width direction. Then, laminated glass is manufactured by following the same process as the manufacturing method for laminated glass using the plate glass manufactured by the plate glass manufacturing method described above.

As described above, in the above embodiment, the ends G2B, G2B in the width direction of the glass ribbon are heated more strongly than the central part G2A in the width direction in the upstream region of the molten metal bath 21, and the multiple top rolls 23 are rotated such that the peripheral speed of the upstream top roll 23A in the direction of travel F1 is slower than the peripheral speed of the downstream top roll 23B. As a result, the viscosity of the ends G2B, G2B in the width direction does not increase as much as that of the central part G2A in the width direction, and the width of the glass ribbon spreading out on both sides of the rotation axis of the upstream top roll can be widened, making it easier to spread the glass ribbon G2 in the width direction upstream of the molten metal bath 21, and the thickness of the ends G2B, G2B in the width direction of the glass ribbon G2 can be made thinner, and the central part G2A in the width direction can be made thicker.

Furthermore, the ratio W/N of the distance W between the two side walls 27, 27 upstream of the shoulder 27A of the molten metal bath 21 (distance between the two first walls 27B, 27B) and the distance N between the two side walls 27, 27 downstream of the shoulder 27A of the molten metal bath 21 (distance between the two second walls 27C, 27C) is set to be greater than 1.0 and less than or equal to 1.6. This makes it difficult for the molten metal 22 to flow upstream X1, and makes it difficult for the glass ribbon G2 to reciprocate (swing) in the width direction Y. Therefore, it is possible to suppress variations in the wedge angle of wedge-shaped glass obtained by cutting the plate glass obtained by the plate glass manufacturing method of this embodiment.

Next, embodiments of the present invention will be described. Using the glass manufacturing apparatus 1 shown in Figures 1(A) and (B), convex glass 100 according to Examples 1 to 15 was manufactured. Examples 1 to 14 are embodiments, and Example 15 is a comparative example.

In Examples 1 to 15, the distance W between the two side walls 27, 27 upstream of the shoulder 27A of the molten metal bath 21 (the distance between the two first walls 27B, 27B), the distance N between the two side walls 27, 27 downstream of the shoulder 27A of the molten metal bath 21 (the distance between the two second walls 27C, 27C), and their ratio W/N were as shown in Table 1. Examples 1 to 14 satisfy the above formula "1.0 < W/N ≤ 1.6", but Example 15 does not satisfy the above formula.

In Examples 1 to 15, the position where the first wall 27B and the shoulder 27A are connected was at a position relative to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), as shown in Table 1. Examples 1 to 15 satisfied the above-mentioned condition "position between 60% and 75% from the upstream wall 25".

In Examples 1 to 15, the position where shoulder 27A and the second wall 27C are connected was at a position relative to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)), as shown in Table 1. Examples 1 to 15 satisfied the above-mentioned condition "a position between 65% and 85% from the upstream wall 25."

In Examples 1 to 15, the temperature and viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface at a position 20% from the upstream wall 25 (0.2L downstream in the X2 direction from the upstream wall 25) relative to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)) were as shown in Table 1. Examples 1 to 15 satisfied the above-mentioned condition "viscosity of 10^(4.5) (dPa・sec) or more". Also, Examples 1 to 15 satisfied the above-mentioned condition "viscosity of 10^(6.0) (dPa・sec) or less".

In Examples 1 to 15, the temperature I and viscosity of the central part G2A in the width direction of the glass ribbon G2 on the molten metal surface at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) relative to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)) were as shown in Table 1. Examples 1 to 15 satisfied the above-mentioned condition "viscosity of 10^(4.7) (dPa・sec) or more". Also, Examples 1 to 15 satisfied the above-mentioned condition "viscosity of 10^(6.3) (dPa・sec) or less".

In Examples 1 to 15, the temperatures K at both ends of the molten metal 22 in the width direction at a position 32% from the upstream wall 25 (0.32L downstream X2 from the upstream wall 25) relative to the length L from the upstream wall 25 to the downstream wall 26 (see Figure 1(B)) were as shown in Table 1. Furthermore, the difference between temperature I and temperature K (I-K) was as shown in Table 1. Examples 1 to 14 satisfied the above-mentioned condition "(I-K) is 62°C or less".

In Examples 1 to 14, the maximum width c in the width direction Y of the glass ribbon G2 in the molten metal bath 21, the width b at the downstream end, and their ratio c/b were as shown in Table 1. Examples 1 to 14 satisfied the above-mentioned condition "1.4 ≤ c/b ≤ 2.2".

In Examples 1 to 14, the width a of the glass ribbon G2 at a position 35% from the upstream wall 25 (0.35L downstream in the X2 direction from the upstream wall 25) relative to the length L from the upstream wall 25 to the downstream wall 26, the minimum width b of the glass ribbon G2 in the width direction Y in the molten metal bath 21, and their ratio a/b were as shown in Table 1. Examples 1 to 14 satisfied the above-mentioned condition "1.0 ≤ a/b ≤ 1.9".

In Examples 1 to 14, with respect to the length L from the upstream wall 25 to the downstream wall 26, at a position 20% from the upstream wall 25 (0.2L downstream in the X2 direction from the upstream wall 25), the length A (not shown) in the width direction Y of the glass ribbon G2, the length B (not shown) in the width direction Y of the molten metal surface not covered by the glass ribbon G2, and their ratio A/B were as shown in Table 1. Examples 1 to 14 satisfied the above-mentioned condition "4 ≤ A/B ≤ 11".

In Examples 1 to 15, top rolls 23 were placed at both ends of the molten metal bath 21 in the width direction Y. The advance speed V (m/h) of the glass ribbon G2 in the slow cooling section 30 was set as shown in Table 2.

Table 2 also shows the maximum T (mm) and minimum M (mm) thickness of the glass plate (convex glass) obtained under the above manufacturing conditions, the thickness t of the widthwise central part G2A of the glass ribbon G2 in the annealing section 30, the difference (T-M) (mm), and the ratio T/M.

The angles α (see Figure 5(B)) of the convex glass obtained under the above manufacturing conditions were as shown in Table 1. In all of Examples 1 to 14 except for Example 15, the angle α was within the preferred range of 0.020° to 0.050°.

Furthermore, in all Examples 1 to 15, the maximum distance (swing width) moved in the width direction Y over 30 minutes at the point where the glass ribbon G2 is cut was less than 1.5 inches, and was kept to a small value. However, in Example 15, when the maximum distance (swing width) moved in the width direction Y over 30 minutes at the point where the glass ribbon G2 is cut was kept to less than 1.5 inches, the angle α became 0.017°, and it was not possible to make the angle α greater than or equal to 0.020°. If an attempt were made to manufacture a convex glass with an angle α of 0.020° or greater in Example 15, the viscosity of the glass ribbon G2 would need to be increased, which would result in a larger swing width of 2.0 inches or more.

The above describes preferred embodiments of the method for manufacturing convex plate glass according to the present invention. However, the present invention is not limited to these embodiments, and various improvements are possible without departing from the spirit of the present invention.

In the melting section 10, the glass raw material is melted into molten glass G1 in the melting furnace 11. However, it is preferable to remove stainless steel contained in the glass raw material using a metal detector before introducing it into the melting furnace 11. Stainless steel contains iron, nickel, chromium, etc. Conventional metal detectors can distinguish between metals and nonmetals, but they cannot arbitrarily distinguish only stainless steel. Therefore, if stainless steel is removed from the glass raw material, the iron necessary for melting the glass raw material is also removed. The metal detector used to remove stainless steel has one coil and distinguishes between stainless steel and iron by the magnetic field generated by the coil. Iron is magnetized by the alternating magnetic field emitted from the transmitting coil. Magnetic field lines are attracted to the iron, and by detecting this with a differential receiving coil, the iron is detected. In addition, eddy currents are generated in the stainless steel by the alternating magnetic field emitted from the transmitting coil, and a magnetic field is generated near the stainless steel. By detecting this change in magnetic field with a differential receiving coil, the stainless steel is detected. The phase of eddy currents generated in stainless steel lags by approximately 90° compared to the phase of the transmitting coil, allowing for the distinction between stainless steel and iron by detecting the phase angle. The phase angle of iron is 40-80°, while that of stainless steel is 140-180°. The larger the amplitude of the eddy currents generated in stainless steel, the larger the size of the stainless steel. The metal detector is installed, for example, on a conveyor that transports the mixed glass raw materials to the melting furnace 11. Preferably, the metal detector has a mechanism to remove only stainless steel of a certain size or larger from the glass raw materials. An example of such a mechanism is shown. When metal or non-metal passes through the metal detector, two analog signals, X and Y, are input from the metal detector to a PLC (Programmable Logic Controller), and the phase angle and maximum voltage are calculated. When the phase angle is between 140 and 180°, indicating stainless steel, and the maximum voltage is above a preset value, a damper installed on the conveyor opens, removing glass raw materials containing stainless steel of a certain size or larger from the conveyor and preventing the stainless steel from being fed into the melting furnace 11.

This application is based on the Japanese Patent Application No. 2021-141551 filed on August 31, 2021, and its contents are incorporated herein by reference.

1. Glass manufacturing apparatus 10: Melting section 11, Melting furnace 12, Twill 13, Lip 20, Molding section 21, Molten metal bath 21U, Upstream end 22, Molten metal 23, 23A, 23B, Top roll 24, Heater 24A, Central heater 24B, End heater 25, Upstream wall 26, Downstream wall 27, Side wall 27A, Shoulder 27B, First wall 27C, Second wall 30, Annealing section 31, Annealing chamber 32, Convex roll 100, Convex glass (flat glass)
200 Wedge-shaped glass 300 Windshield 301, 302 Wedge-shaped glass 303 Interlayer 400 Windshield 401 Wedge-shaped glass 402 Glass 403 Interlayer 500 Wedge-shaped glass 507 Convex surface 503 Line segment 504 Intersection (first point)
505 Intersection 506 Second point

Claims (15)

A method for manufacturing a glass plate, comprising floating a glass ribbon on the surface of a molten metal bath and advancing it, and bringing a plurality of top rolls into contact with both ends of the glass ribbon in the width direction to form the glass ribbon into a plate shape,
The molten metal bath comprises an upstream wall, a downstream wall, and two side walls.
Each of the two side walls includes a shoulder that reduces the width of the molten metal bath in the direction of the glass ribbon's movement.
The ratio W/N of the distance W between the two side walls upstream of the shoulder of the molten metal bath and the distance N between the two side walls downstream of the shoulder of the molten metal bath is greater than 1.0 and less than or equal to 1.6.
A method for manufacturing a glass plate, comprising heating the ends of the glass ribbon more strongly in the width direction than the center in the width direction in the upstream region of the molten metal bath, thereby producing a glass plate where the center in the width direction is thicker than the ends. A method for manufacturing a plate glass according to claim 1, wherein the glass ribbon is heated so that, at a position 20% from the upstream wall relative to the length from the upstream wall to the downstream wall, the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(4.5) (dPa·sec) or more. A method for manufacturing a glass plate according to claim 1, wherein the glass ribbon is heated such that, at a position 20% from the upstream wall with respect to the length from the upstream wall to the downstream wall, the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^(6.0) (dPa·sec) or less. A method for manufacturing a glass plate according to claim 1, wherein, at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, the difference between the temperature of the center of the glass ribbon in the width direction on the molten metal surface and the temperature of both ends of the molten metal in the width direction is 62°C or less. A method for manufacturing a glass plate according to claim 1, wherein the glass ribbon is heated such that, at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^( 4.7 ) (dPa·sec) or more. A method for manufacturing a glass plate according to claim 1, wherein the glass ribbon is heated such that, at a position 32% from the upstream wall with respect to the length from the upstream wall to the downstream wall, the viscosity of the central part of the glass ribbon in the width direction on the molten metal surface is 10^( 6.3 ) (dPa·sec) or less. The method for manufacturing a glass plate according to claim 1 , wherein the ratio of the maximum width in the width direction of the glass ribbon in the molten metal bath to the length in the width direction of the glass ribbon at the downstream end of the molten metal bath is 1.4 to 2.2. A method for manufacturing a glass plate according to claim 1, wherein the ratio a/b of the width a of the glass ribbon at a position 35% from the upstream wall to the length b of the glass ribbon in the width direction at the downstream end of the molten metal bath is 1.0 to 1.9, with respect to the length from the upstream wall to the downstream wall . A method for manufacturing a plate glass according to claim 1, wherein, with respect to the length from the upstream wall to the downstream wall, at a position 20% from the upstream wall, the ratio A/B of the widthwise length A of the glass ribbon to the widthwise length B of the molten metal surface not covered by the glass ribbon is 4 to 11. A method for producing wedge-shaped glass, comprising cutting a plate glass obtained by the method for producing plate glass described in any one of claims 1 to 9. The aforementioned wedge-shaped glass has at least one main surface that is convex,
A method for manufacturing a wedge-shaped glass according to claim 10, wherein, on a line segment passing through the centroid G of the convex surface and connecting two opposing sides of the four sides of the convex surface by the shortest distance, the point at which the wedge-shaped glass has a smaller vertical thickness when the wedge-shaped glass is placed on a horizontal surface is designated as the first point, and the point on the convex surface located at a distance of 2/5 of the length of the line segment from the first point is designated as the second point, and the angle between the line connecting the first point and the second point and the horizontal plane is 0.020° to 0.050°. The method for manufacturing wedge-shaped glass according to claim 10 , wherein the ratio T/M of the maximum and minimum thicknesses T of the wedge-shaped glass is 1.10 to 1.40. A wedge-shaped glass is obtained by cutting a plate glass obtained by the plate glass manufacturing method described in any one of claims 1 to 9.
The aforementioned wedge-shaped glass and other plate glass are laminated and pressed together with an interlayer in between.
A method for manufacturing laminated glass. The other glass plate is the wedge-shaped glass.
The method for manufacturing laminated glass according to claim 13. The other glass plate is a glass plate of constant thickness.
The method for manufacturing laminated glass according to claim 14.