JP3217176B2 - Method and apparatus for manufacturing float glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for producing float glass.

[0002]

2. Description of the Related Art In the production of float glass, a glass ribbon is formed while continuously supplying molten glass to a horizontal bath surface of a bath tub containing molten metal, and the glass ribbon is drawn by a drawing force pulling up from an outlet of the bath tub. It is molded to the target thickness. Next, the glass ribbon is pulled out from the outlet of the molten metal bath, conveyed on a lift-out roll, carried into a lehr, and gradually cooled. The glass ribbon is exposed to the outside air between the molten metal bath outlet and the lehr, and is affected by the temperature. Warping that occurs when producing thick thick example 2mm or more glass sheets of Mi, in order to generate a normal permanent deformation zone, (usually 480 ° C. to 530 ° C. in a soda-lime glass) upstream that is, the temperature of the annealing zone in the annealing furnace kill in pairs response in the control. Therefore, the temperature distribution between the outlet of the molten metal bath and the kiln has almost no influence on the warpage.

On the other hand, in the molding of thin e.g. 2mm or less of the thin glass of Thickness, higher temperature of five hundred and thirty to six hundred ° C.
The temperature distribution affects the warpage in the temperature range of. That is,
In forming thin glass having a thickness of 2 mm or less, 530 to 6
Easily deformed by transient distortion occurs at 00 temperature range of ℃ occurs while the deformation at a temperature controlled subsequent slow the cooling kiln may not be repaired, there is a residual Ru problems become warped product.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method and apparatus for manufacturing a float glass capable of manufacturing a thin glass sheet without warpage.

[0005]

According to the present invention, a glass ribbon is formed while continuously supplying molten glass to a horizontal bath surface of a molten metal bath containing molten metal, and the glass ribbon is discharged from the molten metal bath. molded into the target thickness at a stretching force to pull from a method of manufacturing a float glass for conveying the glass ribbon annealing kiln, between the outlet and the annealing kiln of the molten metal bath, in the width direction of the glass ribbon A method and apparatus for manufacturing a float glass characterized by adjusting a temperature distribution.

A description will be given below with reference to the drawings. FIG. 1 is a sectional view of an apparatus suitable for carrying out the manufacturing method of the present invention. Glass ribbon 1 is desired Thickness in the molten metal bath 2,
After being formed into a width, the temperature is adjusted to a temperature at which plastic deformation can be finally performed by an electric heater 3 provided at the upper end of the bathtub downstream end, and is pulled out from the outlet of the molten metal bathtub 2 by the pulling force of the lift-out roll 4 and the layer roll 5. It is transported on the lift-out roll 4.

Next, the glass ribbon 1 is transported into the annealing furnace 6. A temperature adjusting device 19 is provided between the outlet of the molten metal bath 2 and the inlet of the lehr 6, as described later, to prevent the glass ribbon 1 from contacting the outside air and fluctuating the temperature distribution in the width direction. In. A molten mixed gas of hydrogen and nitrogen is supplied to the molten metal bath 2 from a pipe 7 provided in the upper structure, and the inside of the bath is always maintained at a pressure higher than the atmospheric pressure. A reducing atmosphere flows out of an outlet of the molten metal bath 2 from which the glass ribbon 1 is drawn.

In order to prevent the molten metal 8 in the molten metal bath 2 from being contaminated by the pressure drop in the molten metal bath 2 and the intrusion of oxygen, the drape 9 is arranged at a level not in contact with the glass ribbon. Glass ribbon 1 is pulled out
Reducing atmosphere flowing out of the outlet of the molten metal bath 2 is burned along the upper surface of the glass ribbon 1, the temperature change and local heating occurs in the width direction of the glass ribbon 1 by frame <br/> over arm caused by the combustion . Therefore, it is desirable to use a drape 9 made of stainless steel in order to prevent the drape 9 from being deformed by the heat and causing the lower surface level to be unbalanced.

[0009] Under the lift-out roll 4, dross box 10 is provided, a direction perpendicular to the traveling direction of the glass ribbon 1 between the inside dross box 10 and the outlet and the lift-out roll 4 of the molten metal bath 2 Is provided with a pipe 11. This pipe 11 blows out an inert gas such as nitrogen near the center of the lower surface of the glass ribbon. The inert gas is preferably ejected after preheating to 400 to 600 ° C. This is to prevent the glass ribbon from being locally cooled by the inert gas. The inert gas dilutes the hydrogen concentration in the reducing atmosphere flowing out of the bathtub 2 and suppresses temperature fluctuations and local heating caused by the combustion flame.
Anti-contamination of the pressure drop and the bathtub in the bathtub along with the kill in control
Kill at stop.

A drape hood 12 made of steel is provided above the lift out roll 4.
2 is covered with a heat insulating material 13 to prevent heat radiation. A drape 9 is arranged above the contact point between the glass ribbon 1 and the lift-out roll 4. A drape heater 14 is provided between the drapes 9 and 9 in close contact with the drape hood 12 so that the temperature distribution in the width direction of the glass ribbon 1 can be adjusted. Reference numeral 17 denotes a dross box heater, which can adjust the temperature distribution in the width direction of the glass ribbon 1 similarly to the drape heater 14.

FIG. 2 is a plan view of the upper structure of FIG. 1, showing the arrangement of the electric heater. Is in the drape hood 12 disposed drape heater 14 of two rows between drape 9,9, each drape heater is subdivided in the width direction, cut with precision controls the upper surface temperature of the glass ribbon 1.

FIG. 3 is a plan view of the lower structure of FIG. The dross box 10 in which the lift-out rolls 4 are housed in the lower part of the temperature control chamber is made of a steel material and is not actively kept warm by the conventional apparatus, but is an apparatus for manufacturing thin glass in which the present invention is implemented. Then, dross box 10
It is characterized the entire inner surface to a point that prevents heat radiation to the lower and side covered with a heat insulating material 15. A seal block 16 made of graphite is installed below each lift-out roll 4 in order to shut off an air flow between the bathtub 2 and the lehr 6.

Two rows of dross box heaters 17 are arranged between the lift-out rolls 4 and 4 in the dross box 10 so as to face the drape heater 14 with the glass ribbon 1 interposed therebetween. Dross box heater 17
Cut at precisely adjusted even lower surface temperature of the glass ribbon 1 are subdivided similarly in the widthwise direction. Dross box heater 17
Regarding the above, it is sufficiently effective to dispose only the side portions to prevent the heat radiation from the side.

The warpage generated in the thin glass is caused by the temperature difference between the upper and lower surfaces of the glass ribbon 1 and the glass ribbon 1 between the outlet of the molten metal bath 2 and the inlet of the lehr 6.
Is a thermal deformation that occurs due to the temperature distribution in the width direction.
Therefore, the temperature difference between the upper and lower surfaces of the glass ribbon 1 is reduced, and the temperature distribution in the width direction of the glass ribbon 1 is adjusted by a drape heater, a dross box heater, and the like. The glass ribbon 1 is conveyed to the annealing furnace 6 after the temperature is precisely adjusted in the area. 18 is a canopy.

[0015]

In the formation of a thin glass sheet having a thickness of 2 mm or less, deformation is easily caused by temporary strain generated in a higher temperature range than in a gradually cooled region.
This deformation is not repaired in the subsequent slow cooling process and remains as warpage in the product. The temperature range corresponds to 500 to 600 ° C., a glass ribbon viscosity eta (unit: poise) is logη
= 11-17.

In the present invention, the non-uniform temperature drop in the vertical and width directions of the glass ribbon in the plastic state is suppressed by the active heat retention of the dross box, and precisely by the electric heater subdivided in the vertical and width directions. by adjusting the temperature, it suppression of warpage in the molding of thin glass.

[0017]

According to the present invention, the temperature of the glass ribbon can suppression precisely adjusted warpage in a high temperature range in the molding of thin glass. The wear usually high flatness glass having a curvature 500MR (meters radius) or more surface smoothness even in the production of glass Thickness in manufacturing.

[Brief description of the drawings]

FIG. 1 is a sectional view of an apparatus in which the present invention is implemented.

FIG. 2 is a plan view of the superstructure of FIG. 1;

FIG. 3 is a plan view of the lower structure of FIG. 1;

[Explanation of symbols]

 1: glass ribbon 2: molten metal bath 4: lift-out roll 6: slow cooling kiln 10: dross box 12: drape hood 14: drape heater 17: dross box heater 18: canopy 19: temperature controller

Claims (4)

(57) [Claims] 1. A glass ribbon formed while continuously supplying molten glass on a horizontal bath surface of the molten metal bath containing a molten metal, the target Thickness at a stretching force to pull the glass ribbon from the exit of the molten metal bath In the method for manufacturing a float glass in which the glass ribbon is conveyed to an annealing furnace, the temperature distribution in the width direction of the glass ribbon is adjusted between an outlet of the molten metal bath and the annealing furnace. Method for producing float glass. Wherein the glass ribbon is formed while continuously supplying molten glass on a horizontal bath surface of the molten metal bath containing a molten metal, the target Thickness at a stretching force to pull the glass ribbon from the exit of the molten metal bath In a float glass manufacturing apparatus for forming a glass ribbon into a glass ribbon and transferring the glass ribbon to a lehr, a temperature controller for adjusting a temperature distribution in a width direction of the glass ribbon between an outlet of the molten metal bath and the lehr. An apparatus for manufacturing float glass, comprising: Wherein in said bath outlet, lift-out roll for transferring while pulling the glass ribbon is disposed in the dross box, dross box according to 請 <br/> Motomeko 2 Ru insulating structure der float Glass manufacturing equipment. Wherein in said bath outlet, apparatus for manufacturing a float glass according to 請 Motomeko 2 or 3 that have a device to mitigate the burning of reducing atmosphere filled in the tub.