JP2001031434A - Forming of plate glass and forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method and a forming apparatus, capable of producing a plate glass excellent in desired plate thickness shape, surface accuracy, warping and internal stain. SOLUTION: In this forming apparatus, a formed body 2 having nearly wedge- shaped cross section and having an over flow groove 2a in the upper part is arranged in a forming chamber 1a comprising a heat-insulating wall 1, and an opening 1b is provided under the forming chamber 1a. Heating elements 3 are each arranged in close to melted glass 4 which is made to flow down through side wall faces 2b every prescribed division in lateral width between the heat-insulating wall 1 and the side wall face 2b of the formed body 2 and the output of each heating element 3 can each independently be controlled. This forming method comprises feeding melted glass 4 to an over flow groove 2a of the formed body 2, making the melted glass 4 flow over both sides of the formed body 2, controlling the temperature of melted glass 4 which is made to flow down through the side wall faces 2b every prescribed division in the lateral width and mixing melted glass together in the lower top 2c of the formed body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forming method and a forming apparatus for forming sheet glass from molten glass.

[0002]

2. Description of the Related Art Generally, when manufacturing thin sheet glass,
The molten glass is supplied to the overflow groove formed on the upper part of the molded body having a substantially wedge-shaped cross section, and the molten glass overflows from both sides of the overflow groove to flow down the side wall surfaces on both sides of the molded body. 2. Description of the Related Art A sheet glass forming method is known in which glass is fused at a lower top portion of a formed body to form one sheet glass.

[0003] The molding apparatus used in the above molding method includes:
As shown in FIG. 2, the molding chamber 1 formed by the heat retaining wall 1
a, a molten glass 4 is supplied to the overflow groove 2 a of the molded body 2, and the molten glass 4 is overflowed to the both sides of the molded body 2. The glass sheet 5 is formed by flowing down the wall surface 2b and fusing at the lower apex 2c of the molded body 2, and is drawn out through the opening 1b. A plurality of rod-shaped heating elements 3 are provided on both sides of the molded body 2. The structure is arranged in parallel.

In the molding apparatus as described above, it is difficult to control the temperature of the molten glass 4 flowing down the side walls 2b on both sides in the width direction of the molded body 2, and the side walls on both sides of the molded body 2 are difficult to control. The molten glass 4 flowing down 2b has a difference in thickness in the width direction of the sheet glass 5 formed under various conditions, and the thickness distribution in the width direction of the formed body 2 at the lower top 2c of the formed body 2 is finely adjusted. It was difficult to do. Therefore, a method of locally changing the viscosity of the glass by locally heating or cooling in the width direction of the plate glass 5 in a region where the plate glass 5 is formed immediately below the molded body 2 to finely adjust the thickness is adopted. It has been.

[0005]

However, when the molten glass 4 is fused and formed into a single sheet of glass 5 and then locally heated or cooled, local residual stress in the formed sheet of glass 5 is reduced. Since the internal strain due to the difference remains, there is a problem that a step of removing the strain by heat treatment is required later. In addition, since the formed glass sheet 5 is locally stretched again, there is a problem that accuracy such as surface flatness is adversely affected.

An object of the present invention is to provide a sheet glass forming method and a forming apparatus which solve the above problems.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for forming a glass sheet, comprising: supplying molten glass to a molded article having a substantially wedge-shaped cross section and having an overflow groove at an upper portion; In a method of forming a glass sheet by overflowing the molten glass and flowing down the side wall surfaces on both sides and then fusing each molten glass at a lower top portion of the molded body to form a glass sheet, the molten glass flowing down the side wall surface of the molded body The temperature is adjusted for each predetermined section in the width direction of the molten glass, and the molten glass in at least a part of the section in the width direction of the molten glass is temperature-controlled for each predetermined section in the flowing direction. Is preferred.

Further, the sheet glass forming apparatus of the present invention comprises a heat insulating wall having an opening below and forming a forming chamber, and a formed body provided in the forming chamber and having a substantially wedge-shaped cross section for forming the sheet glass. The molded body has an upper portion in which the molten glass overflows on the upper portion, a side wall surface for flowing down the molten glass overflowing on both sides of the overflow groove, and a lower portion of the molten glass after flowing down the side wall surface. A plurality of heating elements are disposed in close proximity to the molten glass flowing down the side wall surface of the molded body, for each predetermined section in the lateral width direction, further comprising: It is preferable to arrange a plurality of heating elements in close proximity to the molten glass in at least some of the sections in the width direction of the glass for each predetermined section in the flow-down direction.

[0009]

According to the present invention, since a plurality of heating elements are arranged in close proximity to the molten glass flowing down the side wall surface of the molded body in each predetermined section in the width direction, each heating element is independently provided. By performing the temperature control, it becomes possible to adjust the temperature in the width direction of the molten glass flowing down for each predetermined section,
By controlling the temperature of each heating element, changing the viscosity of the molten glass flowing down the side wall surface for each predetermined section in the width direction and partially controlling the flow rate of the molten glass, the thickness of the formed glass sheet is reduced. It can be uniform over a wide width direction. In addition, since a plurality of heating elements are arranged in close proximity to the molten glass in at least a part of the section in the width direction of the molten glass for each predetermined section in the flowing direction, each heating element is independently temperature-controlled. By performing the control, it is possible to adjust the temperature in the flowing direction of the molten glass for each predetermined section, and by performing the temperature adjustment to form an optimal temperature distribution in the height direction for forming the sheet glass, the temperature can be stabilized. To form sheet glass.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of an embodiment of the present invention. In the figure, 1 is a heat retaining wall, 1a is a molding chamber formed by the heat retaining wall 1, 1b is an opening, 2 is a molded body,
2a is an overflow groove, 2b is a side wall surface of a molded body,
2c is the lower top, 3 is the heating element, 4 is the molten glass, 5
Denotes sheet glass, and the same parts as those in FIG. 2 are denoted by the same reference numerals.

First, an example of a sheet glass forming apparatus according to the present invention will be described.

As shown in FIG. 1, the sheet glass forming apparatus of the present invention has an overflow groove 2a having a substantially wedge-shaped cross section and a molten glass 4 at an upper portion inside a forming chamber 1a formed of a heat insulating wall 1. The molded body 2 is disposed, and an opening 1b through which the sheet glass 5 molded by the molded body 2 passes is provided below the molding chamber 1a. A predetermined section in the width direction of the molten glass 4 flowing down between the heat retaining wall 1 of the molding chamber 1a and the side wall surface 2b of the molded body 2, for example, a plate having a width of 100 mm, a length of 400 mm, and a thickness of 10 mm every 150 mm The heating elements 3 processed in a shape are arranged in parallel and close to each other, and each of the heating elements 3 is connected to a power supply device (not shown) capable of individually controlling the output.

The molding chamber 1a is formed by a heat insulating wall 1 made of a ceramic refractory having high heat insulation and no dust generation. Convection is prevented.

The molded body 2 is made of a ceramic refractory whose surface has corrosion resistance to the molten glass 4.
An overflow groove 2a is formed in the upper part with a substantially wedge-shaped cross section, and one end of the overflow groove 2a communicates with a glass melting furnace (not shown) to supply the molten glass 4. On both sides of the molded body 2, the molten glass 4 overflowing from the overflow groove 2a is divided into two, and the side walls 2b, 2b flow down as molten glass 4 having a substantially uniform thickness. The lower apex portion 2c where the side wall surfaces 2b and 2b intersect is formed in a sharp shape so that the respective molten glasses 4 flowing down the side wall surface 2b are fused into one sheet glass 5 without intervening bubbles or the like. .

The heating elements 3 are made of carbon, silicon carbide, etc., which generate heat when energized. Each of the heating elements 3 is provided with a thermocouple (not shown) so that the surface temperature can be independently controlled automatically. Are connected to a power supply (not shown). When using the heating element 3 in which dust generation cannot be avoided, the surface may be covered with a ceramic refractory that does not generate dust. Such a plurality of heating elements 3 are formed on the side wall surface 2 of the molded body 2.
By arranging in parallel every 150 mm in the width direction of the molten glass 4 flowing down b, the molten glass 4 flowing down the side wall surface 2b can be heated every 150 mm in the width direction. Further, as shown in FIG.
Output control can be performed by dividing a part or all of the plurality of heating elements 3 arranged in parallel and adjacent to the molten glass 4 flowing down b at every predetermined section in the flowing direction, for example, every 100 mm. By substituting the plurality of heating elements 3a, it becomes possible to adjust the temperature distribution in the flowing direction of the molten glass 4 for each predetermined width dimension.

Next, an example of the method for forming a sheet glass according to the present invention will be described.

The method for forming a sheet glass of the present invention comprises the steps of:
The molten glass 4 is supplied to the overflow groove 2a, the molten glass 4 overflows from the overflow groove 2a to flow down the side walls 2b on both sides of the molded body 2, and the molten glass 4 flowing down the side wall 2b is moved in the width direction. For each predetermined section, for example, 15
The temperature is adjusted by automatically controlling each of the heat generating elements 3 independently for each 0 mm width, and is formed into one sheet glass 5 while being fused and stretched at the lower top 2c of the formed body 2.

In place of the heating element 3, a plurality of heating elements 3a are arranged so as to be arranged in predetermined sections in the flowing direction, for example, 100 m.
By automatically controlling the temperature for each m, the temperature distribution of the molten glass 4 in the predetermined section in the width direction can be adjusted for every 100 mm in the flowing direction, and the stretching of the sheet glass 5 can be further stabilized. Can be.

In the present invention, the thickness of the molten glass 4 flowing down the side wall surface 2b of the molded body 2 is determined by the heating elements 3 and 3a arranged as described above for each predetermined section in the width direction and for each predetermined section in the flowing direction. Since it can be adjusted every time, even if the thickness of the formed sheet glass 5 in the width direction changes,
It is not necessary to adjust the temperature in the region below the lower apex 2c of the compact 2 as in the prior art, the plate thickness shape having a wide uniform plate thickness portion, the internal strain having a substantially uniform distribution within a desired range, The sheet glass 5 having extremely excellent warpage and surface accuracy within the range of (1) can be stably obtained.

[0020]

The method and apparatus for forming a glass sheet of the present invention can continuously produce a glass sheet having the desired thickness, internal distortion, warpage and surface accuracy with the above-described structure. It has a practically excellent effect.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a sheet glass forming apparatus of the present invention, wherein (A) is a view showing an arrangement of a heating element, (B) is a sectional view of a main part,
(C) is an explanatory view of a preferred heating element.

FIG. 2 is an explanatory view of a conventional sheet glass forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat insulation wall 1a Molding chamber 1b Opening 2 Molded object 2a Overflow groove 2b Side wall surface 2c Lower top part 3, 3a Heating element 4 Molten glass 5 Sheet glass

Claims (4)

[Claims] 1. A molten glass is supplied to a molded article having a substantially wedge-shaped cross section and having an overflow groove at an upper portion, and the molten glass overflows from both sides of the overflow groove of the molded article to flow down both side wall surfaces. In a sheet glass forming method of forming a sheet glass by subsequently fusing each molten glass at a lower top portion of the formed body, the temperature of the molten glass flowing down the side wall surface of the formed body is adjusted for each predetermined section in the width direction. A sheet glass forming method characterized by the above-mentioned. 2. The method for forming a sheet glass according to claim 1, wherein the temperature of the molten glass in at least a part of the section in the width direction of the molten glass is adjusted for each predetermined section in the flowing direction. 3. A heat insulating wall having an opening below and forming a forming chamber, and a formed body provided in the forming chamber and having a substantially wedge-shaped cross section for forming a sheet glass, wherein the formed body is provided at an upper part thereof. Having an overflow groove of molten glass, a side wall surface for causing molten glass overflowing on both sides of the overflow groove to flow down, and a lower apex portion for fusing each molten glass after flowing down the side wall surface to a lower portion, A plate glass forming apparatus, wherein a plurality of heating elements are arranged in close proximity to a molten glass flowing down a side wall surface of a body for each predetermined section in a lateral width direction. 4. The method according to claim 3, wherein a plurality of heating elements are arranged in close proximity to the molten glass in at least a part of the section in the width direction of the molten glass in each predetermined section in the flowing direction. The sheet glass forming apparatus according to the above.