JPH06234533A - Device for producing float glass - Google Patents

Abstract

PURPOSE:To prevent the contamination of a molten metal, disturbance of production due to temp. change, etc., by providing a metal melting furnace outside a molten metal bath and supplying the metal melted in the furnace to the bath. CONSTITUTION:The molten metal 10 is housed in the recessed part on the upper surface of a bottom block 8 being the lower structure of a molten metal bath 30. Molten glass is continuously supplied to the horizontal surface of the molten metal 10 to form a glass ribbon 11, and the ribbon 11 is pulled out of the downstream side of the bath 10 into a desired thickness to produce a float glass. In this case, a metal melting furnace 1 is provided outside the bath 30, and the metal melted in the furnace 1 is supplied to the bath 30 through a launder 3. A reducing atmosphere is preferably supplied to the furnace 1. Consequently, dross due to the reaction between the molten metal 10 and oxygen in the air is not formed on the bath surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to the manufacture of float glass.

[0002]

2. Description of the Related Art In a molten metal bath containing molten metal,
A glass ribbon is formed while continuously supplying molten glass to a horizontal bath surface, and the glass ribbon is drawn out from the downstream end of the bath to be formed into a target thickness. In this forming method, tin is usually used as the molten metal, but when the glass ribbon is pulled out from the downstream end of the bath, a small amount of tin adheres to the lower surface of the glass ribbon due to friction and flows out and is lost from the molten metal bath. On the other hand, tin is evaporated because the temperature inside the molten metal bath is controlled within the range of 600 to 1100 ° C. in order to form the glass ribbon in an appropriate thickness.

Volatiles of tin easily form a compound with the molten glass together with the sulfur content brought into the molten metal bath and the oxygen invading from the outside. Therefore, since the upper space of the molten metal bath is kept airtight and ventilation is performed while supplying a mixed gas of nitrogen and hydrogen to the upper space, a small amount of tin vapor and tin compound vapor are exhausted to the outside of the molten metal bath. To be done. Therefore, it is necessary to replenish tin during operation in the molten metal bath.

Conventionally, since tin is introduced in the form of an ingot from the opening of the side wall of the molten metal bath, oxygen invades from the opening to contaminate the molten tin in the molten metal bath and heat of fusion of the ingot causes molten tin to melt. There was a problem that the temperature fluctuated and the production inhibition such as deterioration of surface irregularity property called distortion of the glass ribbon was caused.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art and provides a float glass manufacturing apparatus which does not cause contamination of molten tin and production inhibition due to temperature fluctuations. The purpose is to

[0006]

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 attached to the molten metal bath. In a float glass manufacturing apparatus that draws from a downstream end to form a target thickness, a melting furnace for melting metal is provided outside the molten metal bath, and the metal melted in the melting furnace is supplied into the molten metal bath. An apparatus for manufacturing float glass is provided.

A description will be given below with reference to the drawings. FIG. 1 is a cross-sectional view of a float glass manufacturing apparatus according to the present invention.
The lower structure of the molten metal bath 30 is made of a refractory called a bottom block 8, and a casing 9 is provided outside the refractory. Molten tin 10 is housed in the recess on the upper surface of the bottom block 8. The glass ribbon 11 is drawn on a horizontal bath surface of molten tin by a pulling force from the downstream end of the molten metal bath to be formed into a desired thickness. On the other hand, molten metal bath 3
An electric heater 13 is arranged in the lower space of the roof tile 12 in the upper structure of No. 0 in order to control the temperature suitable for forming the glass ribbon. A side sealing block 14 is inserted in the gap between the upper and lower structures of the molten metal bath to maintain airtightness in the molten metal bath.

A melting furnace 1 for melting tin is arranged beside the molten metal bath 30, and the melting furnace 1 is arranged on a workbench 2. The melting furnace and the molten metal bath are gutter 3
The side sealing block 14 communicates with each other through the observation window for observing the inside of the bath, and the high temperature tin melted in the melting furnace is made to flow into the molten metal bath by the gutter 3.

FIG. 2 is a sectional view of a tin melting furnace 1 for carrying out the present invention. The melting furnace is covered with a furnace shell 15 made of stainless steel, and has a structure having a melting chamber above a combustion chamber 16.
The heat-insulating bricks 17 were stuck on the inner surface of the combustion chamber to keep it warm. Reference numeral 4 is a gas burner for combustion, and an exhaust duct 6 having a slide damper 5 is arranged on the side wall of the combustion chamber.

A heat insulating brick 18 is arranged in front of the gas burner in the combustion chamber to disperse the flame of the gas burner and avoid local heating. In the melting chamber, a highly conductive material 19 such as graphite is stuck inside a stainless steel furnace shell to prevent contamination of the molten tin 20 and corrosion of the furnace shell 15 by the molten tin. Also, the melting chamber is a partition plate 2 made of graphite.
At 1, the melting section 22 and the cleaning section 23 are separated, and a gap of about 10 mm is provided at the lower end of the partition plate so that they are communicated with each other. An opening 24 is provided in the side wall of the melting portion, and the tin ingot 25 inserted from the opening is melted by conduction heat transfer of the combustion chamber 16 and flows into the clean portion from the gap below the partition plate. ing.

A mixed gas of nitrogen and hydrogen is fed from the pipe 7 above the cleaning section to reduce the contaminated molten tin. The high temperature molten tin sufficiently purified in the reducing atmosphere reaches the level of the sink 3 and is then supplied into the molten metal bath.

[0012]

In the conventional apparatus, the molten tin in the melting furnace provided outside the molten metal bath is combined with oxygen in the air entering through the opening to form dross on the bath surface. In the first aspect, high-temperature and clean molten tin that flows into the refining section through the gap below the partition plate can be supplied without opening the molten metal bath.

[0013]

EXAMPLES Using the apparatus shown in FIGS. 1 and 2, 2 tons of tin was melted per hour while feeding a reducing atmosphere into the cleaning section 23 of the melting furnace 1 at a rate of 10 Nm ³ / h. 60 in a molten metal bath 30 having a temperature gradient in the longitudinal direction.
While replenishing to a place corresponding to the temperature range of 0 to 700 ° C,
Float glass was manufactured. At this time, the molten metal bath 3
The temperature of the molten tin within 0 could be kept constant, and the distortion quality of the product did not change. No dross was found on the tin bath surface in the molten metal bath 30 at the location.

[0014]

According to the present invention, even if replenishment of tin is carried out during production, the molten tin is not contaminated and the production is not hindered by temperature fluctuations, and the productivity can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a float glass manufacturing apparatus according to the present invention.

FIG. 2 is a sectional view of the melting furnace of the present invention.

[Explanation of symbols]

 1: Melting furnace 3: Gutter 4: Gas burner 6: Exhaust duct 10, 20: Molten tin 11: Glass ribbon 13: Electric heater 25: Ingot 30: Molten metal bath

Claims (2)

[Claims] 1. 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 pulled out from a downstream end of the molten metal bath to obtain a target thickness. A float glass manufacturing apparatus for forming a float glass, characterized in that a melting furnace for melting metal is provided outside a molten metal bath, and the metal melted in the melting furnace is supplied into the molten metal bath. apparatus. 2. The manufacturing apparatus according to claim 1, wherein a reducing atmosphere is supplied into the melting furnace.