JP2014193796A - Glass plate production device and glass plate production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass plate production device capable of producing efficiently a high quality glass plate by devising the structure of a top roll.SOLUTION: A glass plate production device includes a float bath 10 for storing molten metal forming a glass ribbon 50b by floating molten glass 50a supplied from the upstream side, and a top roll 20 rotating and simultaneously abutting on the surface of both side edge parts of the glass ribbon 50b, and conveying the glass ribbon 50b to the downstream side, while pulling it to both side outwards in the width direction. The top roll 20 includes a circular base part 21 provided with a cooling structure 25, and an annular abutting part 22 including graphite provided so as to enclose the circumference of the circular base part 21.

Description

  The present invention relates to a glass plate manufacturing apparatus and a glass plate manufacturing method for manufacturing a glass plate by a float process.

  As a method for producing a glass plate, a float method using a production line called a float bath is known. The glass plate manufactured by the float process is used for a flat panel display (a liquid crystal display, a plasma display, an organic EL display, etc.), a solar cell panel, etc., for example.

  The float bath is usually filled with molten tin (melting point: about 232 ° C.) as a molten metal. The float bath filled with molten tin has an internal space surrounded by side walls and a ceiling, and an inert gas (for example, nitrogen, argon) as an atmospheric gas for the purpose of preventing the oxidation of molten tin in the internal space. Etc.) or a mixed gas of an inert gas and a reducing gas is introduced. In the float process, molten glass is supplied onto the molten tin stored in the float bath, and the molten glass spread on the molten tin is led downstream to form a band-shaped glass ribbon. The glass ribbon is pulled outward in the width direction of the glass ribbon by a plurality of top rolls arranged in the vicinity of both side edges thereof, and adjusted to a desired thickness and width.

  The top roll that pulls the glass ribbon includes a roller portion that rotates while contacting the vicinity of the side edge of the glass ribbon, and a rotating shaft portion that is coaxially connected to the roller portion. Here, when the top roll is rotated and the glass ribbon is pulled outward in the width direction, since the glass ribbon has high viscosity, the glass ribbon may wind around and adhere to the contact surface of the roller portion. In order to prevent this, it is necessary to prevent the glass ribbon from being wrapped around the roller portion by appropriately cooling the roller portion and facilitating the separation of the glass ribbon from the roller portion. Therefore, conventionally, the roller portion is cooled by making the rotating shaft portion have a hollow structure and allowing cooling water to flow inside the rotating shaft portion. Thereby, the peelability of the glass ribbon from the roller portion is improved, and the glass ribbon is prevented from being wound around and attached to the roller portion.

  However, if the water cooling structure as described above is provided on the top roll, the entire top roll acts as a cooling body, and therefore, the glass ribbon may be cooled before being formed into a desired shape by the cold air from the top roll. is there. If the temperature of the glass ribbon before molding is excessively lowered, solidification of the glass ribbon proceeds, and it becomes difficult to adjust the thickness and width of the glass ribbon. Further, when a local low temperature region is generated in the float bath due to the cold air from the top roll, this causes a problem that the ambient temperature in the float bath is destabilized and heat loss occurs. Furthermore, the tin compound volatilized from the surface of the molten tin is likely to aggregate in the low temperature region generated in the float bath, and the tin compound aggregate may fall and adhere to the glass ribbon, resulting in product defects. There is also sex.

  As another problem, in the float bath method, molten tin originally under the glass ribbon may adhere to the surface of the glass ribbon. When the glass ribbon is forcibly pulled by the top roll in such a state, the roller part gets wet with molten tin on the surface of the glass ribbon, and as a result, the glass ribbon is wound around the roller part and the production of the glass plate is interrupted. There is.

  Conventionally, there has been a glass plate manufacturing apparatus using a float method in which a heat insulating material is attached to a tip portion of a top roll (see, for example, Patent Document 1). According to the glass plate manufacturing apparatus of Patent Document 1, the glass ribbon before molding is prevented from being excessively cooled by the cooled low temperature roller portion by the heat insulating material attached to the rotating end surface of the roller portion.

  Moreover, in the top roll used for a glass plate manufacturing apparatus, there exist some which covered the area | region except the part which a roller part contact | abuts a glass ribbon with the heat shield (for example, refer patent document 2). According to the glass plate manufacturing apparatus of Patent Document 2, the heat loss in the float bath is reduced by covering substantially the entire cooled top roll with a heat shield.

JP-A-8-277231 JP-A-10-212128

  The glass plate manufacturing apparatuses of Patent Document 1 and Patent Document 2 are intended to prevent the cold air of the top roll from being transmitted to the internal atmosphere of the glass ribbon or the float bath by applying heat insulation measures to the top roll. is there. However, in these glass plate manufacturing apparatuses, since the cooling water flows to the tip of the roller part constituting the top roll, the roller part is made of glass even if heat insulation measures are taken on the rotating end surface of the roller part and the entire periphery. In areas that are in direct contact with the ribbon, it is difficult to avoid excessive cooling of the glass ribbon. If the glass ribbon in the vicinity of the roller part solidifies more than necessary due to the cold air from the roller part, the glass ribbon cannot be sufficiently stretched by the top roll, and as a result, the glass plate that does not satisfy the required quality The area increases, and the yield of the glass plate is deteriorated. Moreover, in the glass plate manufacturing apparatus of patent document 1 and patent document 2, the problem that a top roll tends to get wet with molten tin is not solved.

  The present invention has been made in view of the above problems, and a glass plate manufacturing apparatus and glass plate manufacturing capable of efficiently manufacturing a high-quality glass plate by devising the structure of the top roll. It aims to provide a method.

The characteristic configuration of the glass plate manufacturing apparatus according to the present invention for solving the above problems is as follows.
A float bath in which molten metal that floats molten glass supplied from the upstream side and forms a glass ribbon is stored;
A top roll that contacts the both side edges of the glass ribbon while rotating, and transports the glass ribbon downstream while pulling the glass ribbon outward in the width direction;
A glass plate manufacturing apparatus comprising:
The top roll includes a circular base portion provided with a cooling structure, and an annular contact portion including graphite provided so as to surround a circumference of the circular base portion.

According to the glass plate manufacturing apparatus of this configuration, the top roll includes the circular base portion provided with the cooling structure and the annular contact portion provided so as to surround the circumference of the circular base portion. Accordingly, when the circular base portion is cooled, the annular contact portion is also indirectly cooled by the cold heat of the circular base portion. As a result, the top roll is appropriately cooled as a whole, and the peelability of the glass ribbon from the top roll can be maintained well.
In addition, since the annular contact portion, which is a portion that directly contacts the glass ribbon, is made of a material containing graphite, even if the circular base portion is cooled too much, the glass ribbon is cooled more than necessary due to the heat insulating effect of graphite. Not. As a result, the glass ribbon can be easily adjusted to a desired thickness and width by pulling the glass ribbon with the top roll while preventing the glass ribbon from adhering to the annular contact portion. In addition, because of the heat insulation effect of graphite, local low temperature regions are less likely to be generated in the float bath, so that the atmosphere in the float bath is maintained in a substantially constant state and heat loss is reduced. Moreover, when it becomes difficult to produce a local low-temperature area | region within a float bath, it can also prevent that the tin compound volatilized from the surface of molten tin aggregates and falls on a glass ribbon.
Furthermore, the graphite used for the annular contact portion has a property of low wettability with respect to molten tin. Therefore, for example, even if molten tin adheres to the glass ribbon, there is no possibility that the annular contact portion of the top roll gets wet with the molten tin and winds up the glass ribbon.
Thus, with the glass plate manufacturing apparatus of this configuration, a high-quality glass plate can be efficiently produced in a high yield while appropriately dealing with various troubles that may occur during the production of the glass plate by the float process. It can be manufactured.

In the glass plate manufacturing apparatus according to the present invention,
When the radius of the circular base portion is Ra and the radial width of the annular contact portion is Rb,
Rb / (Ra + Rb) is preferably set in the range of 0.1 to 0.8.

According to the glass plate manufacturing apparatus of this configuration, the annular contact portion is appropriately cooled from the circular base portion by setting the size of the circular base portion and the size of the annular contact portion to the optimal ratio described above. . As a result, the glass ribbon can be easily adjusted to a desired thickness and width while maintaining good peelability of the glass ribbon from the annular contact portion.
In addition, if the ratio is as described above, the heat resistance of the annular contact portion including graphite and the property of low wettability with respect to molten tin can be exhibited more effectively, so a high-quality glass plate can be produced with high yield. And it becomes possible to manufacture efficiently.

In the glass plate manufacturing apparatus according to the present invention,
It is preferable that the circular base portion and the annular contact portion are mechanically joined.

If the top roll is used over a long period of time, the annular contact portion may be gradually worn, and it may be difficult to pull the glass ribbon. In this case, it becomes difficult to adjust the glass ribbon to a desired thickness and width.
On the other hand, in the case of the glass plate manufacturing apparatus of this configuration, since the circular base portion and the annular contact portion are mechanically joined, when the annular contact portion is worn, only the annular contact portion is used. Can be easily replaced with a new one. By the way, if the entire top roll is made of graphite, not only will the equipment cost increase, but the top roll is always exposed to harsh environments, so the entire top roll tends to become brittle. If graphite is used only for the annular contact part and the annular contact part is mechanically joined so as to surround the circumference of the circular base part, the effect of deterioration of the annular contact part is ensured while ensuring the strength of the top roll. The top roll can be configured at a relatively low cost.

In the glass plate manufacturing apparatus according to the present invention,
It is preferable that a heat insulating material is provided on the rotating end surface of the circular base.

  According to the glass plate manufacturing apparatus of this configuration, since the heat insulating material is provided on the rotating end surface of the circular base portion, it is difficult for the cold heat of the top roll to be transmitted to the internal atmosphere of the float bath. For this reason, a local low temperature region is hardly generated in the float bath, the atmospheric temperature in the float bath is stabilized, and heat loss is reduced.

In the glass plate manufacturing apparatus according to the present invention,
It is preferable that two or three top rolls are provided.

  According to the glass plate manufacturing apparatus of this configuration, by providing two or three continuous top rolls, the grip force of the top roll to the glass ribbon can be increased and the glass ribbon can be reliably stretched. Can be easily adjusted to a desired thickness and width. Moreover, since the glass ribbon does not adhere excessively to the two or three continuous top rolls, troubles such as entrainment of the glass ribbon do not occur, and the glass plate can be continuously manufactured. it can. Thus, the glass plate manufacturing apparatus of the present configuration in which the top rolls are arranged in two or three is excellent in the balance between the gripping force for the glass ribbon and the adhesion of the glass ribbon, and the high quality glass plate is made high. It becomes possible to manufacture efficiently with a yield.

In the glass plate manufacturing apparatus according to the present invention,
It is preferable that the circular base portion is configured as a common base portion, and the annular abutting portions are provided in two or three consecutively around the circular base portion.

  According to the glass plate manufacturing apparatus of this configuration, when the top roll is configured, the circular base portion is configured as a common base portion, and two or three annular contact portions are provided around the circular base portion. Thus, the grip force of the top roll to the glass ribbon can be increased while maintaining a relatively simple device configuration. Moreover, excessive adhesion of the glass ribbon to the top roll can also be prevented. As a result, a high-quality glass plate can be efficiently produced with a high yield.

  In the glass plate manufacturing apparatus according to the present invention, the annular contact portion includes a protrusion whose tip is processed into a mountain shape when viewed in the direction of the rotation axis, and the tip angle of the protrusion is 55 to 105 °. It is preferable to be formed.

  According to the glass plate manufacturing apparatus of this configuration, the top roll is securely gripped against the glass ribbon by forming the tip angle of the protrusion of the annular contact portion in the direction of the rotational axis direction at 55 to 105 °. However, excessive adhesion of the glass ribbon to the top roll can be prevented. As a result, a high-quality glass plate can be efficiently produced with a high yield.

The characteristic structure of the glass plate manufacturing method according to the present invention for solving the above problems is as follows.
A glass ribbon forming step of forming a glass ribbon by floating the molten glass supplied from the upstream side on the molten metal stored in the float bath;
A conveying step of conveying the glass ribbon to the downstream side while pulling the glass ribbon outward on both sides in the width direction;
A glass plate manufacturing method comprising:
The transporting step includes a top roll including a circular base portion provided with a cooling structure and an annular contact portion including graphite provided so as to surround a circumference of the circular base portion, on both sides of the glass ribbon. It is to be carried out by contacting the edge surface while rotating.

  According to the glass plate manufacturing method of this configuration, the same excellent effects as those of the glass plate manufacturing apparatus described above are achieved, and high quality while appropriately dealing with various troubles that may occur during the manufacturing of the glass plate by the float method. It becomes possible to manufacture a simple glass plate with high yield and efficiency.

FIG. 1 is a schematic plan view showing the internal structure of the glass plate manufacturing apparatus. FIG. 2 is an explanatory view showing the structure of a top roll having a cooling structure, (a) a cross-sectional side view of the top roll as seen from the flow direction of the glass ribbon, and (b) a direction perpendicular to the flow direction of the glass ribbon. It is the front view of the top roll seen from. FIG. 3 is an enlarged cross-sectional view of the surface of the glass ribbon in the region surrounded by the dotted line P in FIG. FIG. 4 is a graph showing the thickness of the glass ribbon in the boundary region. 5A and 5B are explanatory views showing the structure of a top roll provided with a protrusion, wherein FIG. 5A is a front view showing the entire top roll, and FIG. 5B is a protrusion in a region indicated by a dotted circle in FIG. (C) is a table | surface which shows the result of the extending | stretching test of a glass ribbon. FIG. 6 is a schematic view showing the structure of a top roll in which an annular contact portion and a heat insulating material are integrated. FIG. 7 is an explanatory diagram of a configuration example of a top roll including a plurality of circular base portions and a plurality of annular contact portions. FIG. 8 is an explanatory diagram of a configuration example of a top roll including a common circular base and a plurality of annular contact portions.

  Hereinafter, the embodiment regarding the glass plate manufacturing apparatus of this invention is described based on FIGS. The glass plate manufacturing method of the present invention will be described together in the description of the glass plate manufacturing apparatus. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

[Overall configuration of glass plate manufacturing equipment]
FIG. 1 is a schematic plan view showing the internal structure of the glass plate manufacturing apparatus of the present invention. This glass plate manufacturing apparatus is a part of equipment for manufacturing various glass plates by a float process, and is shown as a glass plate forming apparatus 100 including a float bath 10 and a top roll 20 in FIG.

[Float bath]
The float bath 10 constituting the lower structure of the glass plate forming apparatus 100 is filled with molten tin M. The bath temperature of the float bath 10 is set to be equal to or higher than the melting point of tin (about 232 ° C.), and is normally maintained at 600 to 1300 ° C. When molten glass is supplied to the float bath 10 from an upstream glass melting furnace (not shown), the molten glass spreads on the liquid surface of the molten tin M, and a plate-shaped molten glass 50a is formed.

  The float bath 10 is surrounded by a side wall 11 from the inlet 12 to the outlet 13, and a ceiling (not shown) as an upper structure is provided above the side wall 11. In order to prevent the molten tin M from being oxidized in the inner space surrounded by the liquid surface of the molten tin M, the side wall 11 and the ceiling portion of the float bath 10, an inert gas or a mixture of an inert gas and a reducing gas is used. Gas has been introduced. Examples of the inert gas include nitrogen and argon. The reducing gas is typically hydrogen. An inert gas or a mixed gas of an inert gas and a reducing gas is introduced into an internal space from an air supply pipe (not shown) provided on the side wall 11 or the ceiling, and is also provided on the side wall 11 or the ceiling. It is exhausted to the outside through an exhaust pipe (not shown) or the outlet 13.

  In manufacturing a glass plate using the glass plate forming apparatus 100, the molten glass 50 a is poured from the inlet 12 on the upstream side of the float bath 10, and the molten glass 50 a is floated on the molten tin M on the downstream side. After making it flow and form the strip | belt-shaped glass ribbon 50b (glass ribbon formation process), the said strip | belt-shaped glass flow (glass ribbon) 50b is cooled and solidified, and it carries out as the glass plate 50c from the downstream exit 13. Thus, in the glass plate forming apparatus 100, the molten glass 50a is formed into the glass plate 50c through the glass ribbon 50b.

[Top roll]
Inside the glass plate forming apparatus 100, a top roll 20 for extending the glass ribbon 50b spread on the liquid surface of the molten tin M is provided. A plurality of top rolls 20 are provided so as to pass through the side walls 11 on both sides of the glass plate forming apparatus 100. Each top roll 20 is arrange | positioned so that the shape of the edge of the glass ribbon 50b may be followed. The top roll 20 can also be configured such that the insertion distance from the side wall 11 can be adjusted so as to cope with a change in the width of the glass ribbon 50b. When the glass ribbon 50b is stretched by the top roll 20, as shown in FIG. 1, the top roll 20 is brought into contact with the surface of both side edges of the glass ribbon 50b while rotating, and the glass ribbon 50b is rotated by the top roll 20. It conveys to the downstream side while pulling outward in the width direction by force (conveying step). The glass plate manufacturing method of this invention is implemented by performing this conveyance process following the above-mentioned glass ribbon formation process. In the transporting process, the top roll 20 is appropriately cooled as a whole by a cooling structure to be described later, and has a heat insulating property, so that the peelability of the glass ribbon 50b from the top roll 20 is favorably maintained, The glass ribbon 50b can be easily adjusted to a desired thickness and width.

  Hereinafter, a specific configuration of the top roll 20 will be described. FIG. 2 is an explanatory view showing the structure of the top roll 20 having a cooling structure. 2A is a side cross-sectional view of the top roll 20 as viewed from the flow direction of the glass ribbon, and FIG. 2B is a front view of the top roll 20 as viewed from a direction perpendicular to the flow direction of the glass ribbon. . The top roll 20 includes a circular base portion 21 and an annular contact portion 22 as main components.

<Circular base>
As shown in FIG. 2A, the circular base portion 21 has a rotary shaft portion 23 connected to the rear thereof, and the rotary shaft portion 23 is rotationally driven by a motor 24. When the motor 24 is driven to rotate, the circular base portion 21 rotates together with the rotating shaft portion 23. A cooling channel 25 as a cooling structure is formed inside the circular base portion 21 and the rotating shaft portion 23. Details of the cooling channel 25 will be described later in the item “Cooling of Top Roll”. The circular base portion 21 is disposed in the internal space of the glass plate forming apparatus 100 in a harsh environment, and receives a rotational driving force from the motor 24 so that a large torque acts. For this reason, it is preferable that the circular base 21 is made of a material having heat resistance, corrosion resistance, and rigidity. Examples of the material constituting such a circular base 21 include stainless steel, and other lightweight metal materials such as an aluminum alloy and a titanium alloy can also be used.

<Annular contact part>
As shown in FIG. 2A, the annular contact portion 22 is provided so as to surround the circumference of the circular base portion 21. The annular contact portion 22 is mechanically joined to the circular base portion 21, and the annular contact portion 22 and the circular base portion 21, which are separate members, form a disk-shaped top roll 20. Examples of the mechanical joining method between the annular contact portion 22 and the circular base portion 21 include screwing, screwing, and fixing with a fastening member. In addition, since it is detachable if it is mechanical joining such as screwing, when the annular contact portion 22 is worn, the annular contact portion 22 is removed from the top roll 20 and only the annular contact portion 22 is replaced with a new one. Can be replaced with something.

  The annular abutting portion 22 is an outer peripheral portion of the top roll 20 and abuts on both side edge surface of the glass ribbon 50b. When the motor 24 is driven to rotate, the glass ribbon 50b receives a rotating action from the annular contact portion 22 of the top roll 20 and is pulled outward on both sides in the width direction to adjust the thickness and width. As shown in FIG. 2B, a protrusion (uneven portion) 22a whose tip is processed into a mountain shape is formed on the outer periphery of the annular contact portion 22. By this protrusion 22a biting into the surface of the glass ribbon 50b, the top roll 20 can be reliably stretched and conveyed downstream without idling. Moreover, since the surface area of the outer peripheral portion of the top roll 20 is increased by forming the protrusion 22a on the outer periphery of the annular contact portion 22, a cooling effect of the top roll 20 by air cooling is slightly obtained. It can be moderate cooling. In addition, the protrusion 22a can be configured as a protrusion having a square shape, a trapezoidal shape, or the like in addition to the mountain-shaped protrusion illustrated in FIG.

  Since the annular contact portion 22 is disposed in the internal space of the glass plate forming apparatus 100 in a harsh environment like the circular base portion 21, heat resistance, corrosion resistance, and rigidity are required. Further, since the annular contact portion 22 is in direct contact with the glass ribbon 50b, heat insulation is required so as not to cool the glass ribbon 50b. In the present invention, the annular contact portion 22 is made of a material containing graphite. Since graphite has a higher heat insulating property than a metal material, the cold heat of the circular base portion 21 cooled by the cooling channel 25 described later is difficult to be transmitted to the glass ribbon 50b via the annular contact portion 22. Therefore, the glass ribbon 50b is solidified while the annular contact portion 22 of the top roll 20 is brought into contact with the both side surfaces of the glass ribbon 50b and the glass ribbon 50b is pulled outward in the width direction. The glass ribbon 50b can be easily adjusted to a desired thickness and width. Moreover, since the local low temperature region is less likely to be generated in the float bath 10 due to the heat insulating effect of graphite, it is possible to prevent the tin compound volatilized from the surface of the molten tin M from aggregating and dropping onto the glass ribbon 50b. Further, graphite has a property of low wettability with molten tin. Therefore, for example, even when the molten tin M scatters and adheres onto the glass ribbon 50b while the glass ribbon 50b is being pulled by the top roll 20, the annular contact portion 22 is difficult to get wet with the molten tin M. There is little possibility that the top roll 20 may wind the glass ribbon 50b.

  The annular contact portion 22 containing graphite is manufactured, for example, by filling a mold with carbon powder as a raw material of graphite, press molding, and heat-treating it to graphitize. Alternatively, it is also possible to produce block-shaped graphite by pressure molding and graphitization of carbon powder, and scraping it into the shape of the annular contact portion 22 to manufacture. The carbon powder used as a raw material for graphite may contain other components such as a reinforcing material, an additive, and a release agent. If the graphite content in the annular contact portion 22 is 50% by weight or more, it is possible to realize the top roll 20 that takes advantage of the properties of graphite such as excellent heat insulation and low wettability with respect to molten tin. .

<Size relationship between the circular base and the annular contact portion>
In order to efficiently manufacture the high-quality glass plate 50c with high yield, the balance between the peelability of the glass ribbon 50b from the top roll 20 and the heat insulation of the top roll 20 is also important. Therefore, in the present invention, the size relationship between the circular base portion 21 and the annular contact portion 22 constituting the top roll 20 is optimized. Specifically, as shown in FIG. 2B, the size of the circular base portion 21 and the annular contact portion 22 is set such that the radius of the circular base portion 21 is Ra and the radial width of the annular contact portion 22 is the same. Let Rb. Here, since the protrusion 22a is provided on the outer periphery of the annular contact portion 22, the radial width Rb of the annular contact portion 22 is from the innermost portion of the annular contact portion 22 to the outermost portion of the protrusion portion 22a. To the distance. At this time, the top roll 20 is set so that Rb / (Ra + Rb) is in the range of 0.1 to 0.8, more preferably in the range of 0.3 to 0.7, More preferably, it is set to be in the range of 0.4 to 0.6. By setting the size relationship between the circular base portion 21 and the annular contact portion 22 to the above ratio, the annular contact portion 22 is appropriately cooled from the circular base portion 21. As a result, the glass ribbon 50b can be easily adjusted to a desired thickness and width while maintaining good peelability of the glass ribbon 50b from the annular contact portion 22. Further, if the ratio is as described above, the heat insulating property of the annular contact portion 22 containing graphite and the property of low wettability with respect to the molten tin M can be more effectively exhibited. It becomes possible to manufacture efficiently with a yield.

<Cooling the top roll>
The cooling channel 25 as a cooling structure provided for cooling the top roll 20 is provided inside the circular base 21 and the entire axial length of the rotary shaft 23 as shown in FIG. ing. The cooling channel 25 is connected to a cooling water supply / discharge section 26 for supplying and discharging cooling water. The rotating shaft portion 23 is driven to rotate by the motor 24, and cooling water is poured from the cooling water supply / discharge portion 26 into the cooling channel 25 in the rotating shaft portion 23 as shown in FIG. Then, the cooling water flows from the rotary shaft portion 23 into the circular base portion 21 and makes a round in the circular base portion 21. At this time, heat exchange is performed between the cooling water and the annular contact portion 22. The cooling water that has absorbed heat from the annular contact portion 22 returns from the circular base portion 21 to the cooling water supply / discharge portion 26 through the rotating shaft portion 23 and is discharged outside.

  2A shows a cooling channel 25 in which cooling water flows linearly through the rotating shaft portion 23 and the circular base portion 21 as a cooling structure. For example, a cooling channel formed in a spiral shape can be employed. In this case, since the cooling efficiency is improved, it is possible to reduce the amount of water flowing into the cooling channel. Further, as the cooling structure, a circulating cooling structure can be configured. For example, in the cooling water supply / drainage section 26 for supplying / draining cooling water to / from the cooling channel 25, the water supply side and the drainage side are connected by a circulation pump to form a circulation path, and a cooling machine is provided in the middle of the circulation path as necessary Is installed. In this case, since it is not necessary to guide the water supply / drainage piping to the glass plate forming apparatus 100, the construction of the facility is facilitated. In addition, it is also possible to flow oil or gas as a refrigerant in the cooling channel 25 instead of the cooling water. In this case, since the rotating shaft part 23 and the circular base part 21 do not touch moisture, corrosion from the inside of the top roll 20 can be prevented.

<Top roll insulation measures>
By the way, when cooling the top roll 20, if the cooling water is passed through the cooling channel 25 of the circular base portion 21, the outer peripheral portion 21 a of the circular base portion 21 is thermally insulated by the annular contact portion 22. It is rare that cold heat of the cooling water is transmitted from the outer peripheral portion 21 a of 21 to the internal atmosphere of the float bath 10. However, since the rotating end surface 21 b of the circular base 21 is exposed to the internal atmosphere, the cold heat from the rotating end surface 21 b of the circular base 21 is transmitted to the internal atmosphere of the float bath 10 and is locally contained in the float bath 10. A low temperature region may occur. Therefore, in the present invention, the top roll 20 is provided with a heat insulation measure. For example, in the top roll 20, the heat insulating material 27 is provided on the rotating end surface 21 b of the circular base 21 where the temperature is particularly low. Thereby, the cold heat from the rotating end surface 21b of the circular base 21 is hardly transmitted to the internal atmosphere of the float bath 10, and a local low-temperature region is not easily generated in the float bath 10. As a result, the atmospheric temperature in the float bath 10 is stabilized and heat loss is reduced. Moreover, when it becomes difficult to produce a local low temperature area | region in the float bath 10, it can also prevent that the tin compound volatilized from the surface of the molten tin M aggregates on the top roll 20, and falls on the glass ribbon 50b.

  As a heat insulating material 27 provided on the rotating end surface 21b of the circular base 21 for heat insulating measures of the top roll 20, it is a matter of course that a material excellent in heat resistance and corrosion resistance is preferable. . Examples of the material of the heat insulating material 27 include ceramic and carbon. As a heat insulation measure for the top roll, instead of attaching the heat insulating material 27 to the circular base portion 21, a heat resistant material such as zirconia can be sprayed on the rotating end surface 21 b of the circular base portion 21.

<Glass ribbon stretching test>
When manufacturing the glass plate 50c using the glass plate shaping | molding apparatus 100 of this invention, in order to confirm the effect of the top roll 20 provided with the above-mentioned structure, the extending | stretching test of the glass ribbon 50b was implemented. When the glass ribbon 50b with which the top roll 20 is brought into contact is viewed in the width direction, as shown in FIG. 2 (a), the width of the product effective portion A usable as a product is W1, and the top roll 20 comes into contact with the trace. Is defined as W2, and the width of the boundary region C between the product effective portion A and the trace portion B is defined as W3. In addition, although the product effective part A is an area | region where the thickness of the glass ribbon 50b is formed in predetermined thickness H1 over the whole width direction, in FIG. 2 (a), only one side of the product effective part A is shown. is there.

  FIG. 3 is an enlarged cross-sectional view of the surface of the glass ribbon 50b in the region surrounded by the dotted line P in FIG. As shown in FIG. 3, the boundary region C has an inclined surface whose thickness gradually decreases from the trace portion B to the product effective portion A. FIG. 4 is a graph (solid line) showing the thickness of the glass ribbon 50b in the boundary region C. Here, the vertical axis indicates the thickness of the glass ribbon 50b, and the horizontal axis indicates the distance from the top roll 20. In addition, in FIG. 4, the graph (dashed line) of the thickness of the glass ribbon which extended | stretched using the conventional top roll is written together for reference.

  In the glass plate forming apparatus 100 of the present invention, since the annular contact portion 22 of the top roll 20 is made of a material containing graphite, the heat insulation effect of the graphite prevents the glass ribbon 50b from solidifying, and the width direction It was possible to pull both sides outward enough. For this reason, the inclination of the surface of the boundary region C becomes gentle. When FIG. 4 is seen in detail, the thickness of the glass ribbon 50b in the boundary region C using the top roll 20 of the present invention is substantially constant at a position about 200 mm away from the top roll 20. On the other hand, in the case of using a conventional top roll with insufficient heat insulating effect, the thickness of the glass ribbon was stabilized at a position about 300 mm away from the top roll. Thus, the glass plate manufactured using the conventional top roll could not ensure the product effective part A shown in FIG. 3, and the yield was low.

  Moreover, the heat insulation effect to the glass ribbon 50b near the trace part B with which the top roll 20 abuts was indirectly evaluated from the temperature change of the cooling water between the water supply side and the drainage side of the top roll 20. When the stretching test of the glass ribbon 50b was performed by the glass plate forming apparatus 100 including the top roll 20 in which the annular contact portion 22 of the present invention was made of a material containing graphite, the temperature change of the cooling water was as follows: It was measured as a temperature difference of 6.3 ° C. from the drainage side. On the other hand, when the same glass ribbon stretching test was performed using a conventional glass plate forming apparatus, the temperature change of the cooling water was measured as a temperature difference of 10 ° C. between the water supply side and the drainage side. Since the glass plate forming apparatus 100 of the present invention has a smaller temperature difference of the cooling water than the conventional glass plate forming apparatus, the glass ribbon 50b is formed from the circular base portion 21 by the annular contact portion 22 containing graphite having a high heat insulating effect. It is presumed that the transmission of cold heat to is effectively suppressed. In the glass plate forming apparatus 100 of the present invention, it is visually confirmed that the glass ribbon 50b is not attached to the protrusion 22a on the outer periphery of the top roll 20, and further, the protrusion 22a is damaged, oxidized, Abnormalities such as deterioration were not observed.

  When the glass ribbon 50b is stretched by the glass plate forming apparatus 100 provided with the top roll 20 of the present invention, the glass ribbon 50b is not cooled too much, so that the thickness H1 of the product effective portion A is substantially equal in the boundary region C described above. It was confirmed that the region C1 having the thickness H2 (the width of the region C1 is W4) is widened. Since the boundary region C is used as a margin for cutting out the product effective portion A from the glass plate 50c, the product effective portion A is surely cut out from the glass plate 50c when the margin portion is sufficiently present. In addition, it is possible to reduce the useless portion C2 that cannot be used as the product effective portion A from the molten glass 50a. As described above, according to the present invention, it is possible to efficiently produce a high-quality glass plate in a high yield while solving various problems that may occur in the float process.

<Influence of protrusions formed on the annular contact portion>
The top roll 20 is a member that affects the production efficiency and quality of the glass plate. In particular, since the protrusion 22a formed on the outer periphery of the annular contact portion 22 of the top roll 20 is a portion that directly contacts the glass ribbon 50b, the quality of the glass plate is greatly affected. In order to effectively prevent adhesion of the glass ribbon 50b to the top roll 20 while increasing the grip force of the top roll 20 to the glass ribbon 50b, the present inventors need to set the tip angle θ of the protrusion 22a. The influence of the tip angle θ of the protrusion 22a in glass plate production was examined.

  FIG. 5 is an explanatory view showing the structure of the top roll 20 provided with the protrusion 22a. In the same figure, (a) is a front view showing the entire top roll 20, and (b) is an enlarged view of the protrusion 22a in the region indicated by the dotted circle in (a). In this examination, a top roll 20 was prepared in which the tip angle θ of the protrusion 22a was changed from 45 ° to 115 ° in increments of 10 °, and a stretching test of the glass ribbon 50b was performed using each top roll 20. The test results are shown in the table of FIG. From the test results, when the tip angle θ of the protrusion 22a is in the range of 45 to 105 °, the top roll 20 was able to maintain a sufficient grip force against the glass ribbon 50b. In addition, when the tip angle θ of the protrusion 22a is in the range of 55 to 115 °, excessive adhesion of the glass ribbon 50b to the top roll 20 was not observed. When these results are comprehensively determined, the tip angle θ of the protrusion 22a is formed to be 55 to 105 °, so that the glass to the top roll 20 is securely gripped with respect to the glass ribbon 50b. It has been found that excessive adhesion of the ribbon 50b can be prevented, and as a result, a high-quality glass plate can be produced with high yield and efficiency.

[Other Embodiments]
In the above embodiment, the top roll 20 includes the circular base portion 21 provided with the cooling channel 25 and the annular contact portion 22 provided so as to surround the circumference of the circular base portion 21, and the circular base portion 21. And the annular contact portion 22 are mechanically joined and integrated, and further, the rotary end surface 21b of the circular base portion 21 is provided with a heat insulating material 27. Can also be integrated. FIG. 6 is a schematic view showing the structure of the top roll 30 in which the annular contact portion 22 and the heat insulating material 27 are integrated. The top roll 30 of the present embodiment includes a cap-shaped contact portion 31 made of a material containing graphite, instead of the annular contact portion 22 and the heat insulating material 27 included in the top roll 20 of the above-described embodiment. The cap-shaped contact portion 31 has a concave portion 31 a into which the circular base portion 21 can be fitted. When the circular base portion 21 is fitted into the concave portion 31 a of the cap-shaped contact portion 31, the outer peripheral portion of the circular base portion 21. 21 a and the rotation end surface 21 b are covered with a cap-shaped contact portion 31. The outer peripheral portion 31b of the cap-shaped contact portion 31 serves as a contact surface that contacts the glass ribbon 50b. Accordingly, when the glass ribbon 50b is stretched using the top roll 30 of the present embodiment, the glass ribbon 50b is not cooled more than necessary due to the heat insulating effect of graphite, which is a constituent material of the cap-shaped contact portion 31, so that the glass ribbon 50b is not cooled. The ribbon 50b can be easily adjusted to a desired thickness and width. Moreover, since the cap-shaped contact part 31 of this embodiment can be easily attached or detached with respect to the circular base part 21, the maintenance of the top roll 30 becomes easy.

  When the glass ribbon 50b is rotated while being brought into contact with the glass ribbon 50b to stretch the glass ribbon 50b, it is possible to provide a plurality of top rolls 20 on one rotating shaft portion 23. In this case, the width W2 of the trace portion B where the top roll 20 shown in FIG. 2 (a) comes into contact and a trace remains is slightly widened, but since the force for pulling the glass ribbon 50b by the top roll 20 is increased, the glass ribbon The adjustment range of the thickness and width of 50b can be increased. An embodiment in which a plurality of top rolls are provided on one rotating shaft portion 23 will be described below.

  FIG. 7 is an explanatory diagram of a configuration example of the top roll 20 including a plurality of circular base portions 21 and a plurality of annular contact portions 22. (A) is provided with two top rolls 20A and 20B with respect to the rotating shaft part 23, and (b) is provided with three top rolls 20C, 20D and 20E with respect to the rotating shaft part 23. Is. In the present embodiment, the circular base portion 21 and the annular contact portion 22 that form the respective top rolls 20A to 20E are configured as independent members. However, the circular base portions 21 communicate with each other because the cooling channel 25 is shared. In FIGS. 7A and 7B, the top rolls 20B and 20E positioned on the respective leading ends are provided with a heat insulating material 27 on the rotating end surface 21b of the circular base 21 as a heat insulating measure.

  As shown in FIG. 7 (a) or (b), by providing two or three top rolls 20, the grip force of the top roll 20 to the glass ribbon 50b increases, and the glass ribbon 50b is reliably stretched. Therefore, the glass ribbon 50b can be easily adjusted to a desired thickness and width. Moreover, it was confirmed by the present inventors that the glass ribbon 50b does not adhere excessively to the top roll 20 provided in two or three. For this reason, troubles, such as entrainment of the glass ribbon 50b, do not occur, and the glass plate can be continuously manufactured. As described above, the glass plate forming apparatus 100 according to this embodiment in which the top rolls 20 are provided in two or three is excellent in the balance between the gripping force to the glass ribbon 50b and the adhesion of the glass ribbon 50b, and has high quality. It becomes possible to manufacture a simple glass plate with high yield and efficiency.

  FIG. 8 is an explanatory diagram of a configuration example of the top roll 20 including the common circular base portion 21 and the plurality of annular contact portions 22. (A) is provided with two annular contact portions 22A and 22B in a series with respect to the circular base portion 21 connected to the rotary shaft portion 23, and (b) is a circular shape connected to the rotary shaft portion 23. The annular contact portions 22C, 22D, and 22E are provided in triplicate with respect to the base portion 21. In the present embodiment, since the circular base 21 is shared, the width of the circular base 21 is changed according to the number of annular contact portions 22 attached to the periphery. A heat insulating material 27 is provided on the rotating end face 21b of each circular base portion 21 as a heat insulating measure.

  As shown in FIG. 8 (a) or (b), even when the circular base 21 is configured as a common base, two annular contact portions 22 are provided around the circular base 21 or three. By providing them continuously, the grip force of the top roll 20 against the glass ribbon 50b can be increased. Furthermore, in this embodiment, it is effective in preventing excessive adhesion of the glass ribbon 50b to the top roll 20 while having a relatively simple device configuration. The glass plate forming apparatus 100 of the present embodiment in which the annular contact portions 22 are provided in two or three is excellent in the balance between the gripping force to the glass ribbon 50b and the adhesion of the glass ribbon 50b, and is a high-quality glass. It is possible to efficiently produce the plate with high yield.

  The glass plate manufacturing apparatus and the glass plate manufacturing method of the present invention can be used, for example, for manufacturing thin glass used in flat panel displays (liquid crystal displays, plasma displays, organic EL displays, etc.), solar battery panels, and the like. However, it is also possible to use it for the production of ordinary plate glass such as building glass.

DESCRIPTION OF SYMBOLS 10 Float bath 20 Top roll 21 Circular base part 22 Annular contact part 22a Protrusion part 25 Cooling channel (cooling structure)
27 Heat insulating material 50a Molten glass 50b Glass ribbon 50c Glass plate 100 Glass plate forming device (glass plate manufacturing device)
M Molten tin Ra Radius of circular base Rb Radial width of annular contact part

Claims (8)

A float bath in which molten metal that floats molten glass supplied from the upstream side and forms a glass ribbon is stored;
A top roll that contacts the both side edges of the glass ribbon while rotating, and transports the glass ribbon downstream while pulling the glass ribbon outward in the width direction;
A glass plate manufacturing apparatus comprising:
The said top roll is a glass plate manufacturing apparatus provided with the circular base part in which the cooling structure was provided, and the cyclic | annular contact part containing the graphite provided so that the circumference | surroundings of the said circular base part might be surrounded. When the radius of the circular base portion is Ra and the radial width of the annular contact portion is Rb,
The glass plate manufacturing apparatus according to claim 1, wherein Rb / (Ra + Rb) is set in a range of 0.1 to 0.8.   The glass plate manufacturing apparatus according to claim 1, wherein the circular base portion and the annular contact portion are mechanically joined.   The glass plate manufacturing apparatus as described in any one of Claims 1-3 in which the heat insulating material is provided in the rotating end surface of the said circular base.   The glass plate manufacturing apparatus according to any one of claims 1 to 4, wherein the top roll is provided in two or three.   The glass plate according to any one of claims 1 to 4, wherein the circular base portion is configured as a common base portion, and the annular contact portions are provided in two or three consecutively around the circular base portion. manufacturing device.   The said annular contact part is provided with the projection part by which the front-end | tip was processed into the mountain shape by the rotation axis direction view, and the front-end | tip angle of the said projection part is formed at 55-105 degrees. The glass plate manufacturing apparatus as described in any one of these. A glass ribbon forming step of forming a glass ribbon by floating the molten glass supplied from the upstream side on the molten metal stored in the float bath;
A conveying step of conveying the glass ribbon to the downstream side while pulling the glass ribbon outward on both sides in the width direction;
A glass plate manufacturing method comprising:
The transporting step includes a top roll including a circular base portion provided with a cooling structure and an annular contact portion including graphite provided so as to surround a circumference of the circular base portion, on both sides of the glass ribbon. A method for producing a glass plate, which is carried out by rotating abutting on the edge surface.

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