JP2002193630A - Improvement in method of producing wide sheet glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to stabilize the shape of a glass ribbon to be formed and also to carry stably the glass ribbon to be conveyed on a supporting body. SOLUTION: A pressing roll 24 is arranged in the vicinity of a position on a supporting body 12 wherein a glass ribbon 13 flows down and the surface of the glass ribbon 13 on the pressing roll 24 side is press-held. The pressing roll 24 has a roll substrate having a material or structure capable of containing fluid inside it. This roll substrate introduces, in a fluid state, a vapor film forming agent which is not fluid in the vicinity of normal temperature but fluid at least at a temperature higher than a glass transition temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the production of wide sheet glass, and more particularly to an improvement in a method for producing a wide sheet glass by continuously forming molten glass into a wide sheet glass.

[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 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 molded, the transfer of heat to and from 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 must be close to the temperature of the glass so that the temperature difference between the surface and the inside of the glass ribbon 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 on the glass ribbon caused by gravity due to the vertical forming, and it is difficult to control the glass thickness, which is reduced. 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 that has flowed down onto the support from the glass melting furnace, a tensile force is applied to the glass ribbon by a transport roller or a pinch roller disposed downstream of the forming apparatus. Due to this tensile tension, there is a problem that the upstream side of the glass ribbon rises from the support. Since the raised glass ribbon portion flies in the air without being supported by the support, the shape of the glass ribbon becomes unstable,
The glass ribbon has a drawback that it is apt to be wrinkled or uneven. In addition, there is also a drawback that the conveyance of the glass ribbon becomes unstable and causes meandering or the like.

The present invention has been made in view of such circumstances, and in a manufacturing method of forming a molten glass into a sheet glass using a base material containing a vapor film forming agent, the shape of a formed glass ribbon is stabilized. It is an object of the present invention to improve a method for manufacturing a wide glass sheet capable of stably transporting a glass ribbon transported on a support.

[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 room temperature but is a gas at least above the glass transition point of the glass in a liquid state; and Sliding the film forming agent with each other through a thin layer of a vapor film vaporized by the film forming agent, wherein the liquid is internally filled above the vicinity of the supply position of the glass ribbon supplied to the support. In a roll substrate composed of a material or structure that can be included, a pressing roll is introduced in a liquid state, in which a vapor film forming agent that is not a gas at around normal temperature but a gas at least at a glass transition point is introduced in a liquid state,
The side opposite to the support of the glass ribbon is pressed from above the glass ribbon.

[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 is a view schematically showing a continuous molding apparatus for wide glass sheets 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 holding roll 24 is disposed above the vicinity of the supply position of the glass ribbon 13 supplied to the support 12.
Further, a glass melting furnace 14 for melting the glass raw material is provided at a front side of the molding apparatus 10.
The glass G in a molten state is supplied from above to the support 12. The molten glass G is supplied to a molding apparatus 10 where the support 12
The vapor film forming agent is conveyed through the thin layer 18 of the vaporized vapor film to form the glass ribbon 13 on the support 12.

The glass melting furnace 14 melts a predetermined raw material to be a sheet glass and controls a melting temperature to adjust 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 rotation of the drive roll 20C in the clockwise or counterclockwise direction in FIG. Thereby, the endless belt 20A can move in the direction of arrow 26 or the direction of arrow 28 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. As a result, the support 12 and the glass ribbon 13 are formed into a thin layer 18 of a vapor film.
Make a sliding motion via Further, the belt conveyor 20 is provided with a guide plate 21 for guiding 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 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, and 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 ordinary 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 water can be used as a representative. 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 for the glass ribbon 13 is effective. 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, 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 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.
Is formed of a pair of pinch rollers 22A and 22B provided at the rear of the transport roll 23 on the end portion side (drive roll 20C side) of the glass ribbon 13 by rotating the glass ribbon 13 in the direction of pulling 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 of the glass ribbon 13, it is possible to control the adjustment of the thickness and quality of the formed glass sheet, and to control the glass ribbon 13 in contact with the thin layer 18 of the vapor film. The contact time and the like are varied to control the cooling time and the like.

By the way, in order to form a wide glass sheet stably by such a forming apparatus 10, there is a possibility that the upstream side of the glass ribbon may be lifted by the tension applied by the tension applying apparatus 22. Therefore, it is necessary to improve the shape stability and transport stability of the glass ribbon. Therefore, in the molding apparatus 10 of the present invention, as shown in FIG.
A water-containing substrate roll is disposed above the vicinity of the supply position of the glass ribbon 13 flowing down to the support 12, and the glass ribbon 13
The opposite side of the support is held down.

As shown in FIG. 2, the pressing roll 24 is
A peripheral portion 30 of the roll body is formed of a roll base material capable of containing a vapor film forming agent therein, and both end portions 32 of the roll are formed.
Is formed of a substrate that does not contain a vapor film forming agent, and is configured such that the vapor film forming agent introduced into the roll substrate evaporates from the roll surface. Thus, the thin layer 18 of the vapor film is stably formed between the side of the glass ribbon 13 opposite to the support and the pressing roll 24. As a method for supplying the vapor film forming agent to the roll base material, the rotating shaft 3
By supplying to the central cavity portion 36 formed between the peripheral portion 30 and the peripheral portion 30, it may be made to permeate the entire roll base material, or to the side of the holding roll 24 not facing the glass ribbon 13. Wet rolls (not shown) are placed in contact,
The vapor film forming agent supplied to the wetting roll is
May be transferred. Further, a spray method in which a vapor film forming agent is sprayed on the surface of the holding roll 24 using a nozzle may be used. In short, any method may be used as long as it can be supplied so that the vapor film forming agent is sufficiently contained in the roll base material of the holding roll 24.

The roll base material has a material or structure capable of containing a liquid therein, and for example, a porous or fibrous material can be suitably used. In the case of a porous body,
It is preferably a communication hole. The surface of the porous body has fine pores having a pore diameter of preferably 5 mm or less, more preferably 1 mm or less, and still more preferably 100 μm or less. Further, it is preferable that the material has high affinity with the vapor film forming agent.

As a basic material of the roll base material, porous hydrophilic carbon is particularly preferable, but other materials such as polymer materials derived from natural products such as cellulose, paper, wood and bamboo, and thermoplastic resins 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. The molding surface of the roll base material may be very smooth except for fine holes or fibrous irregularities, and may have certain irregularities. The vapor film forming agent to be used is the same as the vapor film forming agent supplied to the support 12.

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 the form of a ribbon from the glass melting furnace 14 onto the support 12, the water retained 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.

As described above, the support 1 is moved from the glass melting furnace 14.
The falling temperature of the glass ribbon 13 flowing down to 2 is preferably lower, but when the falling temperature is lowered, the upstream side of the glass ribbon 13, particularly the falling part, is easily lifted from the support 12 by the tension applying device 22. Become. Therefore, in the present invention, the holding roll 24 is arranged above the vicinity of the falling position of the glass ribbon 13 flowing down to the support 12 so as to press the glass ribbon 13 on the side opposite to the support. Thereby, even if a tensile force is applied to the downstream side of the glass ribbon 13 by the tension applying device 22, the upstream side of the glass ribbon 13 can be prevented from floating from the support 12, so that the shape of the glass ribbon 13 becomes unstable. Rin, glass ribbon 13
Does not meander. Moreover, between the press roll 24 and the glass ribbon 13, a thin layer 1 of the vapor film is provided.
8 forms a heat insulating layer, so that the glass ribbon 13 does not directly contact the surface of the pressing roll 24. Therefore, it is possible to prevent the glass ribbon 13 from being rapidly cooled, and no contact mark of the pressing roll 24, wrinkles or unevenness remains on the surface of the formed glass sheet. As a result, it is possible to obtain a high quality wide glass sheet having a stable shape and satisfying the uniformity and the surface smoothness.

Although it has been described above that the glass ribbon 13 is prevented from rising from the support 12 by the pressing roll 24, it is necessary to secure a wide glass plate width in the production of the wide glass plate of the present invention. For this purpose, it is preferable to use both the press roll 24 and a means for securing a wide glass plate width.

As means for securing a wide glass plate width, concave portions 12A are provided at both ends of the support 12 as shown in FIG.
12A is formed, and a portion 13 near both ends of the glass ribbon 13 is formed.
A and 13A may be bent toward the concave portions 12A and 12A of the support 12 by gravity. This prevents the flat portion of the glass ribbon 13 from shrinking, thereby ensuring a wide glass plate width.
The bent portions 13A, 13A of both ends act as downward force due to gravity, so that the glass ribbon 13
2 can be further prevented from rising. In addition, since the bent portions 13A, 13A near both ends of the glass ribbon 13 hold the support 12, it is also effective in preventing meandering when the glass ribbon 13 is transported.

As another means for securing a wide glass plate width, rotating gear-shaped members are arranged at both ends in the width direction of the upper surface of the glass ribbon 13 (not shown). By adjusting the angle of the glass ribbon 13 with respect to the advancing method, it may be possible to continuously adjust the securing of a wide glass plate width. In addition, since the rotating gear-shaped member holds both ends of the glass ribbon 13, it is effective in preventing meandering when the glass ribbon 13 is conveyed.

The bent portions 13A, 13A near both ends of the glass ribbon 13 are called so-called ears, which are cut off before shipment of the product, so that the quality of the product sheet glass is not adversely affected.

[0033]

As described above, according to the present invention, the upstream side of the glass ribbon can be prevented from rising from the support, so that the shape of the glass ribbon to be formed and the stability of conveyance can be improved.

[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 cross-sectional view illustrating a holding roll.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Sheet glass shaping | molding apparatus, 12 ... Support body, 12A ... recessed part, 14 ... Glass melting furnace, 16 ... Liquid supply apparatus, 18 ... Thin layer of a vapor film, 20 ... Belt conveyor, 22 ... Tension giving apparatus,
24 ... Pressing roll

Claims (2)

[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.
Introducing a vapor film forming agent which is not a gas at around room temperature but is a gas at least above the glass transition point of the glass in a liquid state; and Sliding the film forming agent with each other through a thin layer of a vapor film in which a film forming agent is vaporized, wherein a liquid is internally filled above the vicinity of a supply position of the glass ribbon supplied to the support. In a roll substrate made of a material or a structure that can be included, a holding roll into which a vapor film forming agent that is not a gas at around normal temperature but is a gas at least at a glass transition point or more is introduced in a liquid state is disposed, A method for manufacturing a wide sheet glass, wherein the side opposite to the support of the ribbon is pressed from above the glass ribbon. 2. The method of manufacturing a wide glass sheet according to claim 1, wherein the glass ribbon is held in a shape bent downward at both ends in the width direction.