JP2001180949A - Roll-molding method for sheet glass product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sheet glass of high quality continuously by roll molding. SOLUTION: A molding method comprises rolls 18 and 20 made of a roll base material consisting of materials or structures which can include vapor film forming agent inside, supplying the vapor film forming agent to the inside of the roll base material from feeder 14, and conveying a glass ribbon GL with a temperature not lower than glass transition temperature by rotating rolls 18 and 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a sheet glass product using a roll, and more particularly to a method for forming a sheet glass product using a roll.

[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, according to the conventional sheet glass manufacturing methods, there are problems with the base material and medium used, and the quality of the sheet glass such as uniformity, uniformity, surface smoothness, etc., depending on each manufacturing method. However, there are problems such as productivity, temperature control during molding, and productivity such as molding time, and none of the production methods is satisfactory.

[0009] In particular, the forming method using a roll has a great advantage that a sheet glass can be formed at low cost because of a simple apparatus configuration. However, as described above, a high-temperature molten glass comes into contact with the roll and suddenly becomes sharp. When cooled, it is unavoidable that contact marks with rolls, wrinkles and irregularities remain on the surface of the formed sheet glass, and the quality of the product deteriorates. In addition, the roll forming method also has a disadvantage that a temperature distribution is easily generated in the glass because the molten glass is greatly affected by the temperature of the roll.

The present invention has been made in view of such circumstances, and makes it possible to form a high quality sheet glass by making the molten glass less susceptible to the temperature of the roll while taking advantage of the roll forming. It is an object of the present invention to provide a sheet glass roll forming method and apparatus.

[0011]

According to the present invention, there is provided a method for forming glass supplied in a molten state into sheet glass, which comprises a material or a structure capable of containing a liquid therein. In the base material, a step of introducing in a liquid state a vapor film forming agent that is not a gas at least near normal temperature but a gas at or above the glass transition point of the glass, and rotating a roll composed of the roll base material, Transferring the glass having a temperature equal to or higher than the glass transition point while forming the glass through a thin layer of the vapor film in which the vapor film forming agent is vaporized.

Further, the glass is formed using at least one pair of rolls made of a roll base material containing the vapor film forming agent.

[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 10 for carrying out the present invention.

The molding apparatus 10 mainly includes a roll device 12 having a plurality of rolls each of which is formed of a roll base material capable of containing a vapor film forming agent therein, and a liquid film forming agent supplied to each roll base material. And a liquid supply device (not shown). Further, a glass melting furnace 16 is disposed at the front stage of the roll forming apparatus 10, and the glass melt G melted from the glass raw material is supplied to the roll apparatus 12 from an outlet 16 </ b> A of the glass melting furnace 16.

The glass melting furnace 16 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 16 is supplied to an exit hole 16A of the glass melting furnace 16.
Is supplied to the roll device 12 as a ribbon-like flow. The glass melt G is supplied to the roll device 12, and then formed as a glass ribbon GL.

The roll device 12 includes a roll 18 and a roll 2
A pair of rolls of 0 is provided in one or more stages. For example, as shown in FIG. 1, the rolls are formed in three stages of a first roll 22, a second roll 24, and a third roll 26. First
The rolls 22, 24, 26 of the first to third stages are sequentially arranged along the transport path of the glass ribbon GL, and are rotated in the direction of the arrow by a rotation drive source (not shown). The clearance between the rolls 18 and 20 in the first to third rolls 22, 24 and 26 is determined by the glass ribbon GL.
It is configured to be narrower on the downstream side of. This allows
The glass ribbons GL are rolls 22 of the first to third stages,
The sheet is gradually thinned by being conveyed while being formed at 24 and 26. In this case, it is desirable that the clearance between the roll 18 and the roll 20 and the number of rotations can be changed so as to be able to cope with a desired thickness of the sheet glass to be formed.

In the rolls 18 and 20, the peripheral surface of the roll body is formed of a roll base material capable of containing a vapor film forming agent therein, and both ends of the roll are formed of a base material containing no vapor film forming agent. The vapor film forming agent introduced into the roll base material is configured to be vaporized from the roll peripheral surface. Thereby, a thin layer of a vapor film is stably formed between the glass ribbon GL and the rolls 18 and 20. As a method of supplying the vapor film forming agent to the roll base material, the vapor film forming agent may be supplied to the center of the rolls 18 and 20 so as to penetrate the entire roll base material, or the glass ribbon GL of the rolls 18 and 20 may be used. A wet roll (not shown) is placed in contact with the side not facing the, and the vapor film forming agent supplied to the wet roll is supplied to the roll 18,
20 may be transferred. Further, a spray method may be used. In short, any method can be used as long as it can be supplied so that the vapor film forming agent is sufficiently contained in the roll substrate.

The roll substrate 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 cellulose, paper, wood, bamboo and other natural polymer materials, 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 and fibrous irregularities, and may have certain irregularities.

As the vapor film forming agent to be used, various organic and inorganic substances which are liquid at normal temperature and gas at or above the glass transition point can be used. Further, from the viewpoint of operability of supply to the roll base material, the melting point is 40.
° C or less, boiling point under atmospheric pressure is 50-500 °
C, more preferably 300 ° C or lower. Furthermore, it is preferable that the vaporized vapor film forming agent does not react chemically enough to adversely affect the glass, has low toxicity, and is nonflammable at the temperature used, and water is typically used. can do. 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 of the vapor film formed by instantaneous vaporization with high heat is significantly smaller than the thermal conductivity of liquid or solid, it forms an adiabatic environment for the glass ribbon GL. be able to.

The method of forming a roll of a sheet glass product of the present invention using the forming apparatus 10 constructed as described above will be described. Note that an example of water will be described as a vapor film forming material.

The glass ribbon GL supplied from the glass melting furnace 16 to the roll device 12 is sequentially formed by the first-stage roll 22, the second-stage roll 24, and the third-stage roll 26 while the temperature is equal to or higher than the glass transition point. While being transported. Thus, the glass ribbon GL is gradually formed into a thin plate glass by receiving the roll pressure from the rolls 18 and 20. In this case, since it is affected by the clearance between the two rolls 18 and 20, the roll temperature, the number of rotations of the roll, the temperature and the viscosity of the glass ribbon GL, it is preferable to appropriately set the thickness according to the type and thickness of the glass sheet to be formed. .

According to the present invention, when the glass ribbon GL is sandwiched between the rolls 18 and 20 of the first to third rolls 22, 24 and 26, the glass ribbon GL is contained in the roll base material. The water is instantaneously vaporized by the high heat of the glass ribbon GL. Thereby, the glass ribbon GL and both rolls 18,
Water vapor is continuously generated at the interface with the glass ribbon G.
Between L and both rolls 18 and 20, a heat insulating layer is formed by a thin layer of a vapor film. This heat insulation layer allows the glass ribbon GL
Can be prevented from being rapidly cooled. Also,
Since the thin layer of the vapor film is interposed between the glass ribbon GL and the two rolls 18 and 20, the surfaces of the rolls 18 and 20 do not directly contact the glass ribbon GL. No contact marks, wrinkles or irregularities remain. In this case, if the thickness of the thin layer of the vapor film is too small, the risk of direct contact between the rolls 18 and 20 and the glass ribbon GL increases, and the formation of the heat insulating layer becomes insufficient. The surface should be at least 10 μm, preferably at least 50 μm, because it is easily affected by surface irregularities. If the thin layer 40 of the vapor film is too thick, the pressure of the rolls 18 and 20 becomes difficult to be transmitted, so that the thickness is preferably 500 μm or less, more preferably 200 μm or less.

As the vapor film forming agent, various ones can be used as described above, but usually water is preferably used in terms of operability, availability, safety and the like. Further, as the roll substrate, various materials can be used as described above, but a material which easily contains a vapor film forming agent is preferable, and a hydrophilic porous or fibrous material is usually preferable. Can be used.

In the present embodiment, an example has been described in which the roll device 12 is formed with three roll stages of a first roll 22, a second roll 24, and a third roll 26. It is not limited, and it is preferable to set the number of roll stages according to the thickness of the sheet glass to be formed.

Further, as described above, according to the present invention, the molding factors such as the clearance between the two rolls 18 and 20, the number of rotations of the rolls, and the temperature and viscosity of the glass ribbon GL are organically related to each other, so that high quality It is a method of manufacturing a sheet glass, and it is desirable to control these forming factors by computer control.

It should be noted that the present invention provides a plate-like glass product at a low cost by a simpler apparatus than the tin float method, the down-draw method or the fusion method, as well as a high-addition method such as a netted glass or a mold plate glass. It can be applied to the molding of valuable glass products. Further, a high quality sheet glass product having excellent surface properties such as smoothness and flatness can be obtained as compared with the conventional roll-out method.

[0030]

As described above, according to the present invention,
By roll forming, a high quality sheet glass product having excellent surface properties such as smoothness and flatness can be obtained.

[Brief description of the drawings]

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

[Explanation of symbols]

10: forming device, 12: roll device, 14: supply device,
16: glass melting furnace, 18: roll, 20: roll, 22
... 1st roll, 24 ... 2nd roll, 26 ... 3rd roll

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Isamu Kaneko 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Yoshihiro Shiraishi 1-1-1, Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. (72) Inventor Kenji Oda 1-12-1, Yurakucho, Chiyoda-ku, Tokyo Asahi Glass Co., Ltd.

Claims (5)

[Claims] 1. A method for forming glass supplied in a molten state into a sheet glass, wherein the glass is not a gas at least at around normal temperature, but is a gas. Introducing a vapor film forming agent that is a gas at or above the glass transition point in a liquid state, and rotating a roll composed of the roll base material to form glass at a temperature equal to or higher than the glass transition point by the vapor film formation. A step of forming and transporting the agent through a thin layer of a vapor film in which the agent is vaporized. 2. The method according to claim 1, wherein the glass is formed using at least one pair of rolls made of a roll base material containing the vapor film forming agent. 3. The method according to claim 1, wherein the vapor film forming agent is water. 4. The roll forming method for a sheet glass product according to claim 1, wherein both ends of said roll are made of a substrate not containing said vapor film forming agent. 5. The roll base material according to claim 1, wherein said roll base material is made of a hydrophilic porous or fibrous material.
Roll forming method of 2, 3 or 4 sheet glass products.