JP2002047020A - Method of continuously manufacturing wide plate glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture high quality wide plate glass excellent in uniformity of thickness and surface smoothness. SOLUTION: Both the end parts 12A, 12A of the supporting base 12 of the forming device 10 is made folded down shape making a step downward. By that, the vicinity part of both the ends 13A, 13A of the glass ribbon 13 are folded down by gravity to the double end part 12A, 12A of the supporting base 12, and the weight of the vicinity of folding parts of both the ends 13A, 13A are applied to the glass ribbon 13, thereby the glass ribbon doesn't shrink in cross direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous production method for wide glass sheets, and more particularly to a continuous production method for wide glass sheets in which molten glass is continuously formed into wide glass sheets.

[0002]

2. Description of the Related Art As a method for producing a sheet glass, a float method using molten tin, a pulling method, a downdraw method, a fusion method and the like are known.

However, in the above-mentioned float method, since the glass ribbon is floated on a medium having higher thermal conductivity than the glass (on a float bath of molten tin) and formed, heat transfer with the medium is large, The temperature of the medium is very important because it is greatly affected by the temperature of the medium.In addition, the temperature of the medium is set close to the temperature of the glass so that the temperature difference between the glass ribbon surface and the inside during cooling is reduced. Since it is necessary to gradually cool under control, the cooling must be slow, a sufficiently long float bath is required, and the molding time becomes long. In addition, various defects derived from tin often occur in terms of quality. In addition, there is a concern about depletion of tin resources.

On the other hand, in the pulling method, the downdraw method, and the fusion method, it is difficult to control the force applied to the glass ribbon due to gravity due to the vertical molding, and it is difficult to control the thickness of the glass. However, there is a problem that the temperature control of the medium for performing the operation is complicated.

[0005] From such a background, the present applicant has proposed a technique relating to a sheet glass forming method for forming a molten glass ribbon into a plate shape through a thin layer of a steam film using a base material containing a steam film forming agent. (JP-A-9-295819). According to the manufacturing method of the sheet glass, resource saving, energy saving, high quality of the sheet glass, reduction of equipment and operation costs,
It has the effects of facilitating job change and enabling various responses from small-scale production to large-scale production.

[0006]

However, in the conventional manufacturing method disclosed in Japanese Patent Application Laid-Open No. 9-295819, the following problems tend to occur due to the force acting on the glass ribbon during molding. That is, in the transport direction (longitudinal direction) of the glass ribbon, substantially a tensile stress is applied to the glass ribbon by a transport roller or a pinch roller disposed on the downstream side of the forming apparatus. Direction), it is difficult to apply a tensile stress, so that a phenomenon (attenuation) generally occurs in which the width of the glass ribbon shrinks. Due to this phenomenon, a glass ribbon of a desired width cannot be obtained, and wrinkles occur on the surface of the formed sheet glass,
There is a disadvantage that surface smoothness / flatness and uniformity are likely to deteriorate.

The present invention has been made in view of such circumstances, and in a method of forming a molten glass into a sheet glass using a substrate containing a vapor film forming agent, the molten glass is prevented from shrinking in the width direction. Accordingly, an object of the present invention is to provide a continuous production method of a wide sheet glass capable of obtaining a predetermined wide glass ribbon and producing a high quality sheet glass excellent in surface smoothness and uniform thickness.

[0008]

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. In the support made of a material or structure that can be used,
Introducing a vapor film forming agent which is not a gas at around normal temperature but a gas at least at the glass transition point of the glass in a liquid state; and Sliding the film-forming agent through a thin layer of a vapor film vaporized by a film forming agent, wherein the sheet glass is kept in a shape that is hardly shrunk in the width direction near both ends in the width direction of the glass ribbon. It is characterized by being molded into

[0009]

DETAILED 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 and FIG. 2 are views schematically showing a continuous forming apparatus for wide glass sheet for carrying out the present invention.

The molding apparatus 10 mainly includes supports 12, 12,... Formed so as to be able to contain a vapor film forming agent therein;
A liquid supply device 16 for supplying a vapor film forming agent to the support 12;
A belt conveyor 20 for rotating the support 12, a roller 23 for conveying the formed glass ribbon 13, a tension applying device 22 for applying a force in the conveying direction to the glass ribbon 13,
The cooling device 30 is provided with an air blowing nozzle 32 for cooling both ends of the glass ribbon 13 in the forming process. A glass melting furnace 14 for melting the glass raw material is provided on the front side of the molding apparatus 10, and molten glass G is supplied onto the support 12 from the glass melting furnace 14. The molten glass G is supplied to the forming apparatus 10, where the vapor film forming agent is conveyed from the support 12 through the thin layer 18 of the vaporized vapor film, thereby forming the plate glass ribbon 13 on the support 12. Molded.

The glass melting furnace 14 melts a predetermined raw material to be a sheet glass and controls a melting temperature to prepare a molten glass G having a viscosity range and a temperature range suitable for molding. In order to perform such glass molding, it is important that the temperature of the molten glass G in the initial stage of molding be within a predetermined range and that the viscosity of the molten glass G be suitable for molding. That is, the viscosity of the molten glass G is 1
It is in the range of 100 to 1,000,000 poise, preferably 500 to
Preferably, the treatment is performed in a temperature range such as between 100,000 poises.

The molten glass G whose temperature and viscosity have been adjusted by the glass melting furnace 14 is supplied to the exit slit 1 of the glass melting furnace 14.
From 4A, it is supplied on the support 12 as a ribbon-like flow. The molten glass G may be supplied from the glass melting furnace 14 by any method as long as a predetermined glass ribbon can be obtained at the viscosity and the temperature. That is, it may be supplied directly from the orifice, lip, slit, or hole onto the support 12, or may be preformed by a roll or the like (not shown) if excessive cooling can be prevented.

The support 12 may be a continuous unit or a combination of unit units of a predetermined length. Further, the support 12 may be a belt-shaped one, a unit roll continuously arranged, or the like. can do. In the present embodiment, an example will be described in which a plurality of rectangular supports 12, 12,... Are arranged and fixed in the longitudinal direction at regular intervals on the surface of the endless belt 20A of the belt conveyor 20. When the supports 12 are arranged at a small interval in this manner, a groove 12B orthogonal to the moving direction of the glass ribbon 13 is formed between the supports 12.

The endless belt 20A is driven by a driving roll 20C.
And a pair of driven rolls 20D, and is driven by the clockwise rotation of the drive roll 20C in FIG. Thereby, the endless belt 20A
Can move around in the direction of arrow 26 in FIG.
Further, the moving speed of the endless belt 20 </ b> A is set to be different from the traveling speed of the glass ribbon 13 on the support 12. This causes the support 12 and the glass ribbon 13 to slide through the thin layer 18 of the vapor film. Further, the belt conveyor 20 is provided with a guide plate 21 for guiding the upper moving path of the endless belt 20A, and the endless belt 20A
Is moved by the guide plate 21 in a stable manner.

The support 12 is required 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 suitably 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, and still more preferably 100 mm or less.
It has fine pores with a pore diameter of not more than μm. 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 having communicating holes can be suitably used, but other materials derived from natural substances such as cellulose, paper, wood, bamboo, etc. Materials, carbon-based materials and the like can also be used. In addition, metal materials such as iron, stainless steel, nickel, aluminum, platinum, and titanium; metal oxides such as aluminum oxide, zirconium oxide, silicon carbide, and silicon nitride; ceramic materials mainly containing 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.

A vapor film forming agent is supplied to the support 12 from a liquid supply device 16 and the vapor film forming agent is supplied to the glass ribbon 13.
The thin layer 18 of the vapor film is formed between the plurality of the arranged supports 12, 12... And the glass ribbon 13 by instantaneous vaporization with the high heat.

As the vapor film forming agent, various organic and inorganic substances which are liquid at normal temperature and are gas at least at the glass transition point or higher can be used. Further, in view of the operability of supply to the support 12, the melting point is 40
° C or less, boiling point under atmospheric pressure is 50-500 °
C, more preferably 300 ° C or lower. Further, the vaporized vapor of the vapor film forming agent is applied to the glass and the support 12.
Does not react chemically enough to adversely affect
It is preferably non-flammable at the temperatures used, and typically water can be used. in this way,
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 13 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 significantly smaller than the thermal conductivity of a liquid or a solid, an adiabatic environment is effective for the glass ribbon 13. Can be formed.

The liquid supply device 16 for supplying the vapor film forming agent to the support 12 is mainly composed of a bathtub 29 provided below the belt conveyor 20. The endless belt 20A moves around and a pair of rolls 20C is provided. , 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 29. Thereby, the vapor film forming agent is supplied from the liquid supply device 16 to the support 12. In addition, as the liquid supply device 16,
It is not limited to a bathtub type, and for example, a type in which a vapor film forming agent is sprayed on the support 12 may be used,
Alternatively, the liquid in the bath may be once contained in a wet roll (not shown), and then the wet roll is brought into contact with the support 12 to supply the vapor film forming agent. Further, a spray type may be used.

The tension applying device 22 includes a belt conveyor 20.
And a pair of pinch rollers 22A and 22B provided at the rear of the transport roll 23 on the end side (drive roll 20C side). The pinch rollers 22A and 22B are pinched and rotated in a direction to pull the glass ribbon 13 in the transport direction. Is applied for conveying and stretching. Pinch roller 22
A and 22B can change the rotation speed. Thus, by adjusting the force applied to the glass ribbon 13 in the transport direction, the adjustment of the thickness and quality of the formed glass sheet is controlled, and the force of the glass ribbon 13 in contact with the thin layer 18 of the vapor film is controlled. The contact time and the like are varied to control the cooling time and the like.

Incidentally, in such a molding apparatus 10,
In order to obtain a glass ribbon 13 having a predetermined width, it is necessary to prevent shrinkage in the width direction. Therefore, in the molding apparatus 10,
As shown in FIG. 2 and FIG. 3, the portions 13A, 13A near both ends in the width direction of the glass ribbon 13 are formed into a sheet glass while being kept in a shape that makes it difficult to shrink in the width direction.

There are various shapes that make the glass ribbon 13 hardly shrink in the width direction, that is, a shape for fixing the width. For example, as shown in FIGS. 2 and 3, one of the effective shapes is to make both ends of the support body 12 bend so that a step is formed downward. This example is an example in which step portions 12A, 12A are provided at both ends of the support 12. In this support 12, portions 13 </ b> A near both ends of the glass ribbon 13, 1.
3A is bent toward the stepped portions 12A, 12A of the support 12 by gravity, so that the flat portion of the glass ribbon 13 can be prevented from contracting in shape. Further, the weight of the bent portions 13A, 13A is applied to the glass ribbon 13 as a tensile force in the width direction, so that the glass ribbon 13 is prevented from shrinking in the width direction. Therefore, a high-quality glass sheet having a predetermined width and a predetermined thickness without wrinkles can be formed. In addition, it is also preferable to provide a cooling device 30 that injects cooling air at the bent portions 13A near the both ends.
The cooling air injected from the nozzle 32 of the cooling device 30 cures the portions 13A, 13A near both ends before the portions 13A, 13A near both ends contact (fall) the step portions 12A, 12A of the support 12. Because it can be. The bent portions 13A, 13A near both ends are called so-called ears, and are cut before shipment of the product, so that the quality of the product sheet glass is not adversely affected. Further, the transport roll 23 and the pinch rollers 22A and 22B are formed in advance in such a shape as to allow the near-end portions 13A and 13A to escape.

On the other hand, a support 12 having a shape having a recess 12C as shown in FIG. 4 is also effective. This recess 1
Since 2C is continuous in the transport direction, the belt conveyor 20 as a whole has a structure in which a groove is formed in parallel with the glass transport direction. The glass ribbon 13 is provided in the recess 12C.
13A, 13A near both ends are swelled and immersed.

A method of forming a sheet glass using the forming apparatus 10 configured as described above will be described. An example of water as a vapor film forming agent will be described.

When the molten glass G is continuously supplied in a ribbon form from the glass melting furnace 14 onto the support 12, the water held on the support 12 is instantaneously vaporized by the high heat of the glass ribbon 13. I do. Thereby, water vapor is continuously generated at the interface between the glass ribbon 13 and the support 12, and the glass ribbon 13
A thin layer 18 of a vapor film is formed between the substrate and the support 12. In this case, the molten glass G usually supplied from the glass melting furnace 14 is supplied to the support 12 at about 950 to 1300 ° C. suitable for molding in the case of ordinary soda lime glass, but if the temperature becomes too high. The generation of steam from the support 12 is so intense that the stable supply operation is hindered,
The durability of various members and devices including the support 12 is also adversely affected. Therefore, depending on the composition of the glass,
Generally, it is preferable that the glass ribbon 13 is allowed to flow down to the support 12 at a temperature not exceeding 1400 ° C. Then, the glass ribbon 13 is cast on the thin layer 18 of the vapor film from the downstream side of the glass melting furnace 14 toward the annealing furnace (not shown), and a tensile force in the transport direction is applied by the tension applying device 22. 3A and 3B, the portions 13A and 13A near both ends of the glass ribbon 13 as shown in FIG.
The plate 12 is formed by controlling the shrinkage in the width direction by the support 12 having the steps 12A, 12A or the recess 12C formed in the length direction of the step 12A in the portion corresponding to 3A.

Therefore, in the forming apparatus 10, since a force in the conveying direction and the width direction can be applied to the glass ribbon 13, a high-quality wide glass sheet satisfying the uniformity and the surface smoothness can be obtained.

[0028]

As described above, according to the present invention, the sheet glass is formed while maintaining the vicinity of both ends in the width direction of the glass ribbon in a shape that does not shrink in the width direction. It can produce high quality wide plate glass with excellent quality.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a continuous wide-pane glass forming apparatus for carrying out the present invention.

FIG. 2 is a plan view of a main part of the continuous wide glass sheet forming apparatus shown in FIG. 1;

FIG. 3 is a cross-sectional view of the continuous molding apparatus for wide sheet glass as viewed from the line 3-3 in FIG. 2;

FIG. 4 is a sectional view showing another embodiment of the support.

DESCRIPTION OF SYMBOLS 10: Sheet glass forming device, 12: Support, 12A: Stepped portion, 12C: Depressed portion, 14: Glass melting furnace, 16: Liquid supply device, 18: Thin layer of vapor film, 20: Belt conveyor , 22
... Tension applying device

Claims (3)

[Claims] 1. A method for continuously forming a molten glass ribbon supplied on a support into a sheet glass, wherein the support comprises a material or a structure capable of containing a liquid therein.
Introducing a vapor film forming agent which is not a gas at around normal temperature but a gas at least at the glass transition point of the glass in a liquid state; and A step of sliding each other through a thin layer of a vapor film in which a film forming agent is vaporized, comprising: a step of holding the glass ribbon in a shape that is hardly shrunk in the width direction at both ends in the width direction of the glass ribbon. Continuous production method of wide sheet glass characterized by being molded into 2. The wide sheet glass according to claim 1, wherein the width of the glass ribbon is reduced by holding the vicinity of both ends in the width direction of the glass ribbon in a downwardly bent shape. Continuous manufacturing method. 3. The continuous wide glass sheet according to claim 1, wherein the shrinkage of the width of the glass ribbon is controlled by holding the vicinity of both ends in the width direction of the glass ribbon in a shape having a downward swelling. Manufacturing method.