JPH02149438A - Glass plate production device - Google Patents

Abstract

PURPOSE:To eliminate the temp. unevenness in the forming atmosphere and to obtain the glass plate of uniform thickness distribution by providing the unit sending preheat air from above a forming body to the vicinity of the forming body and pulling down the plate type glass while it is being cooled. CONSTITUTION:A molten glass supply pipe 3 is connected with the recessed part 2a of the forming body 2. The molten glass 4 supplied to the recessed part 2a from the molten glass supply pipe 3 is overflowed from a slit type opening of the upper part of the recessed part 2a, flowed down along both side surface of the forming body 2, and joined together at the lower end part of the forming body 2. The confluent molten glass 4 is cooled into glass plate 4' and pulled down by a pair of tension rollers 5 revolvingly driven. The unit sending preheat air as the forming atmosphere 1a is provided above the forming body 2. This preheat air keeps the forming atmosphere 1a in high temp., and prevents the air ascending by convection as shown by arrow 11 from flowing into the forming atmosphere 1a by keeping the pressure in the furnace chamber to be positive, where the furnace chamber means the inner chamber enclosed by furnace walls 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass plate manufacturing apparatus, and more particularly to a glass plate manufacturing apparatus that pulls out a glass plate vertically downward.

[Prior Art] As a method for manufacturing a glass plate, a down-draw manufacturing method is known in which a glass plate is pulled vertically downward (see, for example, Japanese Patent Laid-Open No. 112351/1983). In this case, a glass plate is manufactured by causing the molten glass to flow down along both sides of a molded body with a wedge-shaped cross section, to join together at the lower end of the molded body, and then to be pulled out downward while being cooled.

The molded body is placed above the furnace chamber surrounded by a firebrick furnace wall, and a cooling atmosphere exists below the molded body on the lower side of the furnace chamber to cool the glass plate after molding. .

[Problem that the invention seeks to solve]

In the case of the above-mentioned glass plate manufacturing equipment, an opening is formed at the bottom of the furnace wall for pulling out the glass plate from the furnace chamber, and other gaps are formed in the furnace wall, so the furnace chamber is not completely sealed. , cold air flows into the furnace chamber from outside. Furthermore, in the atmosphere in which the glass is cooled, the air near the glass plate is strongly heated by the radiant heat of the glass plate, creating a temperature difference with the air in other parts. Therefore, air convection occurs within the furnace chamber due to the inflow of cold external air and the temperature difference in the air in various parts of the furnace chamber.

This convection creates a large upward flow of cold air along the glass plate and into the molding atmosphere in which the wedge-shaped compact is provided. This flow is not constant both locally and over time, which makes the temperature in the molding atmosphere unstable, and the molten glass flowing along the molded body causes temperature unevenness and, as a result, viscosity unevenness. Therefore, in areas where the temperature is low, the fluidity of the molten glass is poor and the glass becomes thick, whereas in areas where the temperature is high, the fluidity is too good and the glass plate becomes thin, resulting in uneven thickness distribution of the glass plate.

The present invention has been made to eliminate the above-mentioned problems and drawbacks, and its purpose is to manufacture a glass plate that can eliminate temperature unevenness in the molding atmosphere and produce a glass plate with a uniform thickness distribution. The purpose is to provide equipment.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides a glass plate manufacturing apparatus in which molten glass is formed into a plate shape by a formed body having a substantially wedge-shaped cross section, and the plate glass is pulled out downward while being cooled. It is characterized by being equipped with a device for sending preheated air from above to the vicinity of the molded body.

[Effect]

The device for sending preheated air into the vicinity of the molded body maintains the vicinity of the molded body at a high temperature and prevents cold air rising due to convection from flowing into the vicinity of the molded body.

[Example] Next, the present invention will be explained in detail based on the example shown in the drawings.

FIG. 1 schematically shows a longitudinal section of the glass plate manufacturing apparatus, and FIG. 2 shows a cross section of the glass plate manufacturing apparatus of FIG. 1 along the line . In the figure, 1 is a furnace wall made of refractory bricks, and 2 is a molded body with a substantially wedge-shaped cross section. The illustrated molded body 2 is a so-called feeding cell having a recess 2a in which molten glass 3 is accommodated. A molten glass supply pipe 3 is connected to the recess 2a of the molded body 2. The molten glass 4 supplied from the molten glass supply pipe 3 to the recess 2a overflows from the upper slint-shaped opening of the recess 2a, flows down along both sides of the molded body 20, and joins at the lower end of the molded body 2. The merged molten glass 4 is cooled and becomes a glass plate 4', which is pulled downward by a pair of rotationally driven pulling rollers 5. In addition, molten glass 4
Alternatively, in order to control the temperature of the glass plate 4', a heating device, a water cooling plate, etc. (not shown) are provided at appropriate positions within the furnace wall 1.

Above the molded body 2, preheated air is supplied to the molding atmosphere (the molded body 2
A device is provided for feeding the material into the area (where the material is located) la. This device consists of a blower and an air heating device 6 (not shown). The air heating device 6 includes a guide plate 7 that guides the air in a meandering manner and a heater 8 provided between the guide plates 7 in order to uniformly heat the air.

Further, a thermocouple 9 and a baffle plate 10 are provided at the outlet 6a of the air heating bag W6.

Air from a blower (not shown) flows into the air heating device 6 from an inlet 6b, is guided in a serpentine shape by a guide plate 7 within the device 6, is heated to a predetermined temperature by a heater 8, and is then guided to a predetermined temperature by a heater 8. It is guided by the plate 10 and supplied to the molding atmosphere 1a.

The second preheating air is used to maintain the molding atmosphere 1a at a high temperature and to create positive pressure in the furnace chamber (inner chamber surrounded by the furnace wall 1).
(see arrow 11) from flowing into the molding atmosphere la. As a result, the temperature in the molding atmosphere is stabilized, and the molten glass 4 flowing down along the molded body 2 does not have temperature unevenness and thus viscosity unevenness. Therefore, the molten glass 4 flows uniformly, and the thickness distribution of the glass plate 4' becomes uniform.

Using the above glass plate manufacturing equipment, the temperature was 1060°C1.
Flow ff1lloOf 7 minutes of preheated air, volume approximately 0.1
When the glass plate 4' was supplied to the molding atmosphere 1a at a temperature of 1060°C, the difference between the maximum and minimum thickness when molding the glass plate 4' with an average thickness of 1 opening was 200 μm compared to the conventional case in which no preheated air was fed. It decreased from 90 μm to 90 μm.

Note that the temperature of the preheated air is determined by the selected glass composition, the amount of glass pulled up, and the temperature of the glass overflowing from the molded body.

Further, the flow rate of the preheated air may be any amount that can suppress convection flowing up along the glass plate in the furnace chamber.

The air supplied into the air heating device 6 may be high-temperature air obtained by exchanging waste heat from a glass melting furnace (not shown), but the temperature of this air is such that the molding atmosphere 1a is at a predetermined temperature. It is sufficient if the temperature does not rise above this level.

〔Effect of the invention〕

As explained above, since the present invention is provided with a device that sends preheated air into the vicinity of the molded article, the vicinity of the molded article is maintained at a high temperature, and the low temperature air that rises due to convection is directed to the vicinity of the molded article. prevent the influx of Therefore, the temperature near the molded body is stabilized, the molten glass flows uniformly, and unevenness in the thickness of the glass plate can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of a glass plate manufacturing apparatus according to an embodiment of the present invention, and FIG. 2 shows the glass plate manufacturing apparatus of FIG.
FIG. 3 is a cross-sectional view taken along a line. 1... Furnace wall, 1a... Molding atmosphere, 2...
Molded body, 2a... recess, 3... molten glass supply pipe, 4... molten glass, 4'... glass plate,
5... Tension roller, 6... Air heating device, 7... Guide plate, 8... Heater, 9... Thermocouple, 10... Wind guide plate, 11... Cold air Arrow indicating upward flow Applicant: Shizuo Nakamura, agent of Ho-Ya Co., Ltd., patent attorney

Claims (1)

[Claims] 1. In a glass plate manufacturing device that forms molten glass into a plate shape using a molded body with a nearly wedge-shaped cross section and pulls the glass plate downward while cooling, preheated air is introduced from above the molded body into the vicinity of the molded body. A glass plate manufacturing device characterized by being equipped with a feeding device.