JP2001247320A - Improved method for continuously producing wide plate glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide forming apparatus of glass for forming wide plate glass in forming a glass ribbon by using the thin layer of a vapor film. SOLUTION: When molten glass G is flown down from a glass melting furnace 14 in a ribbon form onto a support 12, water held on the support 12 is instantaneously vaporized by the high temperature of the glass ribbon GL to form the thin layer 18 of a vapor film between the glass ribbon GL and the support 12 and the glass ribbon GL is cast onto the thin layer 18 of the vapor film. Subsequently, both lateral ends of the glass ribbon GL are held by a gear like device 15 and transported, in this case, the gear-like device 15 sends out the glass ribbon GL with holding the both lateral ends of the glass ribbon GL by contacting the gear-like device 15 to a surface of the glass ribbon GL without facing to the support 12 and the glass ribbon GL is formed in a state expanded in the width direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet glass forming apparatus and, more particularly, to a sheet glass wide forming apparatus for forming a glass ribbon into a wide sheet glass when forming a glass ribbon using a thin layer of a vapor film.

[0002]

2. Description of the Related Art As a method of forming a sheet glass, a lifting method,
A downdraw method, a rollout method, a fusion method, a tin float method, and the like are known, and a tin glass method which is most widely used at present is a sheet glass forming method. In this method, a molten glass in which a predetermined raw material is melted in a melting furnace is introduced into a molten tin bath in a reducing atmosphere, and is spread and moved in the vertical and horizontal directions using a mechanical external force. It gradually cools to near the point temperature to form a flat glass plate with a smooth surface.Since the smoothness of the product is significantly improved compared to the conventional pulling method, the polishing process is unnecessary. did.

[0003] However, the tin float method is concerned with the depletion of tin resources, the need to maintain a reducing atmosphere using hydrogen gas in order to prevent oxidation of metallic tin,
Tin penetrates into the glass from the surface in contact with tin and adversely affects the quality of the product, is vulnerable to shaking such as earthquakes, takes time to recover production after an earthquake, and consumes a large amount of energy for heating and keeping the glass Problems.

[0004] In addition, in forming a sheet glass by a roll-out method or a tin float method, since a high-temperature molten glass comes into contact with a base material (metal roll) or a medium (tin) having high thermal conductivity, the heat flow between the molten glass and the molten glass is high. The bundle is large and the molten glass is greatly affected by the temperature of the substrate and the medium. Therefore, there is a problem that the temperature control of the substrate and the medium is very important and difficult.

Further, in the roll-out method, since the glass surface is rapidly cooled by contact with the metal roll, it is unavoidable that contact marks with the roll, wrinkles and irregularities remain on the formed sheet glass surface. The quality of the product deteriorates. On the other hand, in the tin float method, it is necessary to perform slow cooling in which the temperature of the tin bath is gradually brought close to the temperature of the glass so as not to generate a temperature distribution on the surface or inside of the glass during cooling, and the molding time is long. Therefore, there is a problem in terms of production efficiency.

In the pulling method, the downdraw method, and the fusion method, both surfaces of the molten glass are brought into contact with air, which is a medium having smaller thermal conductivity than glass, but are caused by gravity due to vertical molding. It is difficult to control the tension on the molten glass, and in any case, the largest stress acts on the uppermost part, making it difficult to control the thickness of the sheet glass and complicating the temperature control of the medium to reduce it. Problem.

Further, as another manufacturing method, a proposal has been made in which a gas such as air is supplied from pores on the surface of a support, and molten glass is spread thereon to form a glass plate (Japanese Patent Publication No. Sho 50-36445).
However, it is extremely difficult to directly and continuously supply a gas and stably maintain a molten or fluid high-temperature glass.

[0008] As described above, the conventional sheet glass manufacturing methods involve problems of the base material and medium to be used, quality problems such as homogeneity, thickness uniformity, and surface smoothness of the sheet glass, and problems in forming. However, none of the production methods was satisfactory.

[0009] From such a background, the present applicant has proposed a basic technique relating to a sheet glass forming method in which molten glass is formed into a plate shape by using a thin layer of a vapor film obtained by vaporizing a vapor film forming agent (Japanese Patent Laid-Open No. Hei 10 (1994)). 9-295819). According to the manufacturing method of the sheet glass, effects such as resource saving, energy saving, high quality of the sheet glass, reduction of equipment and operation cost, easy job change, various correspondences from small-scale production to large-scale production, and the like are exhibited. be able to.

[0010]

However, a method of forming a molten glass into a plate using a thin layer of a vapor film obtained by vaporizing a vapor film forming agent is a novel molding method that goes beyond the conventional idea. Therefore, it is necessary to improve the quality and process by examining the optimum conditions at the time of molding. In particular, when the molten glass on the support is stretched or moved by continuously applying a force in the longitudinal direction at the time of molding, the molten glass shrinks in the width direction, that is, so-called attenuation occurs. As a result, there is a problem that it is difficult to form a wide sheet glass.

The present invention has been made in view of such circumstances, and provides an improved continuous manufacturing method of a wide sheet glass capable of forming a wide sheet glass in forming a sheet glass using a thin layer of a vapor film. The purpose is to.

[0012]

In order to achieve the above object, the present invention provides a method for continuously forming a molten glass ribbon supplied on a support into sheet glass, wherein a liquid is contained inside. Introducing a vapor film forming agent, which is not a gas at least around normal temperature but a gas at or above the glass transition point of the glass, in a liquid state into the support made of a material or a structure which can be used. And sliding the glass at a temperature equal to or higher than the transition point through a thin layer of a vapor film formed by vaporizing the vapor film forming agent, comprising the steps of: Is held and moved by a gear-shaped jig.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view schematically showing a sheet glass forming apparatus for carrying out the present invention, and FIG. 2 is a plan view.

The molding apparatus 10 mainly includes supports 12, 12,... Formed so as to contain a vapor film forming agent therein.
A gear-shaped jig 15 for holding and moving both ends in the width direction of the glass ribbon GL, a liquid supply device 16 for supplying a vapor film forming agent to the support 12, and forming a vapor film on the support 12 and the glass ribbon GL. A belt conveyor 20 that slides relatively through a thin layer 18 of a vapor film in which the agent is vaporized. Further, a glass melting furnace 14 for supplying a glass melt G obtained by melting a glass raw material onto the support 12 is provided on the front side of the molding apparatus 10. After the glass melt G is supplied onto the support 12, It is formed as a glass ribbon GL.

The glass melting furnace 14 melts a predetermined raw material to be a sheet glass and controls a melting temperature to prepare a glass melt G having a viscosity range and a temperature range suitable for molding. Since the viscosity of the glass melt G is controlled by the temperature, the viscosity is simultaneously controlled by controlling the temperature. In the case of molding a sheet glass, the dissolution depends on the glass composition.
In a temperature range of about 00 ° C., the reaction is carried out for a sufficient time so as to eliminate the glass bubble defect, the composition variation, and other defects.

The glass melt G whose temperature and viscosity have been adjusted by the glass melting furnace 14 is supplied to an outlet hole 14A of the glass melting furnace 14.
Is supplied onto the support 12 in the form of a ribbon. The glass melt G can be supplied from the glass melting furnace 14 by any method as long as the glass melt G can be supplied without excessive distribution in viscosity and temperature. That is,
It may be supplied directly from the orifice, lip, or slit onto the support 12 or may be preformed by a roll or the like (not shown) if excessive cooling can be prevented.

The gear-shaped jigs 15 are opposed to three pairs (six in total) at symmetrical positions with respect to the center line 19 (see FIG. 2) of the glass ribbon GL to be formed. Then, while holding both ends in the width direction of the glass ribbon GL, the glass ribbon GL is rotated by a rotation drive source (not shown) to move the glass ribbon GL from a downstream side of the glass melting furnace 14 toward a slow cooling device (not shown). The rotation drive source for rotating the gear jig 15 is capable of adjusting the rotation speed of the gear jig 15 so that the glass ribbon GL can be adjusted.
It is desirable to be able to control the thickness and quality of the glass ribbon and to control the contact time of the glass ribbon GL in contact with the thin layer 18 of the vapor film.

The support 12 may be a continuous unit or a combination of unit units having a predetermined length. Further, the support 12 may be a belt-shaped one, a unit roll continuously arranged, or the like. However, in the present embodiment, an example will be described in which a plurality of supports 12, 12,... Are arranged and fixed so as to be adjacent to the surface of the endless belt 20A of the belt conveyor 20. On the surface of the support 12 formed in this way on the glass ribbon GL side, a groove 12B that is not parallel to the moving direction of the glass ribbon GL is formed. The groove 12B is formed between the support 12 and the thin layer 18 of the vapor film.
This is effective for efficiently releasing excess steam from the interface with the substrate. The endless belt 20A for moving the support 12 is
A drive roll 20 stretched between a pair of rolls composed of a drive roll 20C and a driven roll 20D and capable of rotating forward and reverse.
It is driven by the rotation of C. Thereby, the endless belt 20A can make a circular movement in the forward direction (solid arrow 26 in FIG. 1) or the reverse direction (dashed arrow 28 in FIG. 1). Further, the moving speed of the endless belt 20A depends on the support 1
2 is set to be different from the moving speed of the glass ribbon GL above. As a result, the support 12 and the glass ribbon GL relatively slide through the thin layer 18 of the vapor film. Also,
The belt conveyor 20 is provided with a guide plate 21 that guides the upper movement path of the endless belt 20A, and the upper surface of the endless belt 20A moves stably by being guided by the guide plate 21.

The support 12 needs to have a material capable of containing a liquid therein or a structure capable of containing a liquid therein. For example, a porous body or a fibrous body is used. In the case of a porous body, it is preferably a communication hole. The surface of the porous body is preferably 5 mm or less,
More preferably 1 mm or less, further preferably 100 μm
It has fine holes with the following hole diameters. Further, it is preferable that the material has high affinity with the vapor film forming agent.

As a basic material of the support 12, porous hydrophilic carbon is particularly preferred, but other materials such as cellulose, paper, wood, bamboo and other natural materials, thermoplastic resin In addition, synthetic polymer materials such as thermosetting resins and rubbers, and carbon materials can be suitably used. Also iron,
Metal materials such as stainless steel and platinum, aluminum oxide,
Ceramic materials mainly containing metal oxides such as zirconium oxide, silicon carbide and silicon nitride, metal carbides and metal nitrides can also be used. Note that the molding surface of the support 12 may be very smooth except for fine holes or fibrous irregularities, or may have certain irregularities.

The support 12 is supplied with a vapor film forming agent from a liquid supply device 16, and the vapor film forming agent is supplied to the glass ribbon GL.
The thin layer 18 of the vapor film is formed between the plurality of arranged supports 12, 12,... And the glass ribbon GL by instantaneous vaporization with high heat. The thickness of the thin film layer 18 is preferably 10 μm or more and 500 μm or less.

As the vapor film forming agent, various organic and inorganic substances which are liquid at ordinary temperature and gas at or above the glass transition point can be used. From the viewpoint of the operability of supply to the support 12, it is preferable that the melting point is 40 ° C or less and the boiling point under atmospheric pressure is 50 to 500 ° C, more preferably 300 ° C or less. Further, it is preferable that the vaporized vapor film forming agent does not chemically react so as not to adversely affect the glass, has low toxicity, and is nonflammable at the temperature used. Can be used. As described above, as the vapor film forming agent, it is necessary to appropriately select a liquid capable of instantaneously vaporizing due to the high heat of the glass ribbon GL and forming a stable vapor film. Since the thermal conductivity of the thin layer 18 of the vapor film formed by instantaneous vaporization with high heat is remarkably lower than that of liquid or solid, an adiabatic environment is formed for the glass ribbon GL. can do.

The liquid supply device 16 for supplying the vapor film forming agent to the support 12 is mainly composed of a bath 30 provided below the belt conveyor 20, and the endless belt 20A moves around and a pair of rolls 20C , 20D, the support 12 supported by the endless belt 20A is formed so as to go under the liquid of the vapor film forming agent in the bathtub 30. Thereby, the vapor film forming agent is supplied from the liquid supply device 16 to the support 12. Note that the liquid supply device 16 is not limited to a bathtub type, and may be, for example, a type in which a vapor film forming agent is sprayed on the support 12 or a wet roll (shown in the drawing). ), The wet roll is brought into contact with the support 12 to supply the vapor film forming agent.

An improved continuous manufacturing method of wide glass sheet of the present invention will be described using the wide glass sheet forming apparatus 10 constructed as described above. An example of water will be described as a vapor film forming material.

When the glass melt G flows from the glass melting furnace 14 in the form of a ribbon and flows down onto the support 12, the water held by the support 12 is instantaneously vaporized by the high heat of the glass ribbon GL. Thereby, water vapor is continuously generated at the interface between the glass ribbon GL and the support 12, and a thin layer 18 of a vapor film is formed between the glass ribbon GL and the support 12. In addition, air exists on the upper surface of the glass ribbon GL. Therefore, the glass ribbon GL is sandwiched between the thin layer 18 of the vapor film and the air to form an adiabatic environment. Here, the adiabatic environment means that the glass ribbon GL is covered with a medium (a thin layer of a vapor film, a gas) having a significantly lower thermal conductivity than glass.
An environment in which heating through the medium is not received so much that cooling of L is hindered, and there is an advantage that the temperature distribution in the thickness direction of the glass ribbon GL and the direction parallel to the glass ribbon GL surface in the forming process of the sheet glass can be reduced. . Then, the glass ribbon GL is cast on the thin layer 18 of the vapor film.

In the formation of the glass ribbon GL, if a certain force is continuously applied in the longitudinal direction of the glass ribbon GL to extend or move the glass ribbon GL, the glass ribbon shrinks in the width direction, which causes so-called attenuation. Therefore, when forming a wide plate glass, it is important to expand or secure the width of the glass ribbon in opposition to this attenuation.

In the present invention, both ends in the width direction of the glass ribbon GL are held and moved by the gear-shaped jig 15. In this case, the gear-shaped jig 15 is brought into contact with the surface of the glass ribbon GL that does not face the support 12. This allows
Since the gear-shaped jig 15 feeds out the glass ribbon GL while holding both ends in the width direction of the glass ribbon GL, the glass ribbon GL can be formed in a state of being stretched in the width direction. Therefore, it is possible to prevent so-called attenuation, in which the glass ribbon GL shrinks in the width direction during molding, so that a glass ribbon GL having a predetermined width can be obtained. Further, if the gear-shaped jig 15 acts in a direction to increase the width of the glass ribbon GL, a wide glass ribbon GL can be formed. In order to widen the glass ribbon GL, if the direction of the gear-shaped jig 15 is arranged in an inverted C shape in the moving direction of the glass ribbon GL, a wide sheet glass can be continuously formed.

The number of the gear-shaped jigs 15 can be variously selected according to the target sheet glass width, thickness, quality, and the like.
Is gradually cooled from the downstream side of the glass melting furnace 14 (not shown).
It is preferable to dispose at least at two or more locations along the moving direction of the glass ribbon GL that moves toward. Thereby, the holding force and the moving force can be more reliably applied to the glass ribbon GL. Further, when the gear-shaped jigs 15 are arranged at both ends in the width direction of the glass ribbon GL, two gear-shaped jigs 15 may be provided in parallel with each other. The shape of the gear-shaped jig 15 is such that, as shown in FIG. 3, in addition to those having tooth-shaped projections 17, 17,... On the peripheral surface, as shown in FIG. What has projection 19 may be used. And the stab-like projection 19 is the tooth-like projection 1.
7, the holding force and the moving force with respect to the glass ribbon GL can be improved.

Although various materials can be used for the gear-shaped jig 15, it is preferable to reduce the thermal conductivity in consideration of the influence on the temperature distribution and the like of the glass ribbon GL. . For example, a method in which the gear-shaped jig 15 is formed from a base material containing a vapor film forming agent therein can be suitably used. Accordingly, heat transfer from the glass ribbon GL to the gear jig 15 can be suppressed, so that the influence on the temperature distribution of the glass ribbon GL can be reduced.

Further, when the arrangement position of the gear-shaped jig 15 is viewed in relation to the temperature of the glass ribbon GL, the temperature of the glass ribbon GL cooled while moving is 700 ° C. or higher.
It is preferable to be located in a temperature range of 00 ° C. or less. This is because holding both ends in the width direction of the glass ribbon GL in this temperature range can effectively prevent the glass ribbon GL from shrinking in the width direction during molding. That is, when the temperature of the glass ribbon GL is lower than 700 ° C., the viscosity of the glass ribbon GL becomes too large, and it is difficult to expand or secure the glass ribbon GL in the width direction. On the other hand, when the temperature of the glass ribbon is 11
If the temperature exceeds 00 ° C., the flowability of the glass ribbon GL is too large, and the effect of holding the glass ribbon GL by the gear-shaped jig 15 is small.

In the present invention, the quality of the thin film of the vapor film, the cooling rate, and the molding factors such as the relative sliding between the support 12 and the glass ribbon GL are organically related to each other, and high quality is obtained. It is for manufacturing sheet glass, and it is desirable to control these forming factors by computer control.

[0033]

As described above, according to the present invention,
Along with being able to stably obtain a sheet glass of a predetermined width,
Wide sheet glass can be formed continuously.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a sheet glass forming apparatus for carrying out the present invention.

FIG. 2 is a plan view schematically showing a sheet glass forming apparatus for carrying out the present invention.

FIG. 3 is a perspective view of a gear-shaped jig having tooth-shaped protrusions.

FIG. 4 is a perspective view of a gear-shaped jig having a barbed projection.

[Explanation of symbols]

10: sheet glass forming device, 12: support, 12B: groove,
14: glass melting furnace, 15: gear-shaped jig, 16: liquid supply device, 18: thin layer of vapor film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Oda 1-12-1 Yurakucho, Chiyoda-ku, Tokyo Asahi Glass Co., Ltd. (72) Inventor Shikuni Inoue 1-12-1 Yurakucho, Chiyoda-ku, Tokyo Asahi Inside Glass Co., Ltd. (72) Inventor Gaku Kubo 1-1-1, Suehirocho, Tsurumi-ku, Yokohama, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Yoshihiro Shiraishi 1-1-1, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture

Claims (7)

[Claims] 1. A method for continuously forming a molten glass ribbon supplied on a support into a sheet glass, wherein the support is made of a material or a structure capable of containing a liquid therein. A step of introducing a vapor film forming agent which is not a gas in the vicinity but a gas at or above the glass transition point of the glass in a liquid state; and And a step of sliding each other through a thin layer of a vapor film in which the agent is vaporized, characterized in that both ends in the width direction of the glass ribbon are held and moved by a gear-shaped jig. Improved continuous manufacturing method for wide sheet glass. 2. The method of claim 1, wherein the vapor film forming agent is water. 3. The improved continuous manufacturing method for wide-plate glass according to claim 1, wherein a surface of said glass ribbon not facing said support is held and moved by said gear-shaped jig. 4. The apparatus according to claim 1, wherein said gear-shaped jigs are arranged in pairs symmetrically with respect to a center line passing through the center in the width direction of said glass ribbon. Improved continuous manufacturing method for wide sheet glass. 5. The glass ribbon is held and moved by arranging two or more pairs of gear-shaped jigs arranged in pairs at the symmetric positions along the longitudinal direction of the glass ribbon. An improved continuous production method for wide plate glass according to claim 1, 2, 3, or 4. 6. The apparatus according to claim 1, wherein said gear-shaped jig is made of a base material containing said vapor film forming agent therein.
Improved continuous production of 2, 3, 4 or 5 wide sheet glass. 7. The temperature of the glass ribbon is not lower than 700 ° C.
7. The improved continuous production method of wide plate glass according to claim 1, wherein the glass ribbon is held and moved by the gear-shaped jig when the temperature is between 100 [deg.] C. or less.