JPH0769648A - Glass fusing furnace - Google Patents

Abstract

PURPOSE:To provide the glass fusing furnace capable of continuously and stably supplying fused glass without causing the glass remaining without being fused and insufficient clarity even with a small amt. of glass. CONSTITUTION:This tank type glass fusing furnace has at least a charging section 8 for charging glass raw materials, a fusing and clearing vessel 1 for fusing and clearing the glass and an outflow nozzle for discharging the fused glass. This fusing and clearing vessel is provided therein with one or plural partition plates 7 forming the flow passages for the glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass melting furnace for continuously melting glass, and more particularly, a very small tank furnace type continuous glass melting furnace with a pulling rate of several kilometers to several hundreds of kilometers / day. It is about.

[0002]

2. Description of the Related Art Conventional glass melting furnaces have several dozens per day.
It can be roughly divided into a tank furnace that continuously processes a large amount of glass in units of several hundred tons, and a batch-type crucible furnace that processes a small amount of glass of several tons or less per day. In addition, there is a small tank furnace made of platinum etc. for the production of some optical glass, but this is basically a structure in which a large furnace is simply reduced, and the daily production amount is In the case of units, crucible furnaces are still used.

[0003]

In recent years, attention has been focused on a precision reheat pressing method in which a glass material which has been softened by heating is directly press-molded in a molding die instead of a method of processing an optical element by grinding and polishing.

In this method, glass melted by a conventionally used glass melting furnace is cold processed into a shape suitable for molding, or molten glass is mass-formed into a shape suitable for direct molding. It is molded at once and prepared as a glass material, and the glass material made there is reheated and used as needed.

However, the method of stocking the glass material once and reheating it in this way is wasteful from the point of view of energy and because of additional steps such as cleaning for removing dirt and the like, and molding from melting. Direct molding is required for consistent production.

However, in order to continuously produce an optical element having a very small diameter such as a lens used in an optical system of a camera or a video camera by direct molding,
There is a need for a melting furnace capable of continuously and stably melting and supplying a very small amount of high-quality glass without waste.

However, a batch type crucible furnace suitable for small-quantity production has a difficulty in continuity, and since it is a batch type, it wastes a lot of glass and is not suitable for such a purpose. For this purpose, the tank furnace type is good,
At present, the tank furnace currently used has not been developed for small-scale production.

[0008] One of the reasons why it has not been developed is that since there was no need for a continuous small-scale tank furnace in the past, the development of a full-scale small continuous furnace was not actually carried out. However, there are problems as described below from the technical point of view.

As the scale of the glass melting furnace becomes smaller,
The influence of the turbulence of the glass flow is likely to occur, and simply decreasing it will cause the flow velocity of the glass to decrease, causing some areas to flow and some areas not to flow, resulting in unmelted parts, inclusion of bubbles and striae. Easier to do.

Further, since it is small, it becomes difficult to provide a temperature distribution for controlling the flow.

An object of the present invention is to provide a glass melting furnace for producing an optical element by direct molding. More specifically, even if a small amount of glass is left unmelted, insufficient clarification and striae occur. It is another object of the present invention to provide a glass melting furnace capable of continuously and stably supplying molten glass.

[0012]

Means for Solving the Problems The present invention which achieves the above object comprises at least a charging section for charging a glass raw material, a melting and refining tank for melting and refining glass, and an outflow nozzle for discharging the molten glass. In a tank-type glass melting furnace equipped with
It is a glass melting furnace in which one or a plurality of partition plates that form a glass flow path are provided inside the melting and refining tank.

Further, the present invention includes that the height of the partition plate is higher than the liquid level of the glass in the melting and refining tank.

Further, according to the present invention, the partition plate is fixed to the bottom of the melting and refining tank so that the partition surface of the partition plate for partitioning the glass flow is perpendicular to the glass flow direction. Is included.

The present invention also includes that one or a plurality of partition plates have one end fixed to the side wall of the melting and refining tank.

Further, the present invention includes that a charging section for charging the glass raw material is provided in the melting and refining tank.

The present invention also includes the provision of a charging section in the melting and refining tank by means of a partition plate having a hole for allowing molten glass to pass therethrough.

Further, according to the present invention, a melting and refining tank for melting and refining glass, a homogenizing tank for agitating the melt-clarified glass and homogenizing it, and agitating the homogenized glass for adjusting the outflow temperature. To the outflow tank, which is sequentially connected by a connecting pipe,
The outflow tank has an outflow nozzle, and a heating means capable of arbitrarily controlling the temperature is provided around each of the tanks, the connection pipes, and the outflow nozzle.

[0019]

[Function] In a glass melting furnace capable of continuously melting and supplying glass, the flow of the molten glass is controlled by providing a partition plate that forms a flow path of the glass in the melting and refining tank, and also in the tank. Since the residence time of the glass increases, even in a small glass melting furnace, it is possible to continuously melt and supply clear glass without leaving unmelted glass and mixing of bubbles, and efficient melting processing even with a small amount of glass. Is possible.

The partition plate has a height higher than the height from the bottom of the tank to the liquid surface of the glass, and the partition surface for partitioning the glass flow is perpendicular to the glass flow direction. By being fixed to the bottom of the tank, the above effect becomes more reliable.

Further, in the case of a smaller melt refining tank,
In addition to the above structure, one or more of the partition plates are fixed to the side wall of the melting and refining tank, so that the flow of glass is reliably controlled.

Further, by providing a partition plate, the temperature of the heating means such as a heater installed near the outer periphery of the tank can be arbitrarily controlled to facilitate the temperature control of the glass along the glass flow. It is possible to greatly improve the maneuverability in a small continuous glass melting furnace.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 FIG. 1 is a plan view of a glass melting furnace according to the present invention as seen from above, and FIG. 2 is a view of the glass melting furnace AB- shown in FIG.
4 is a cross-sectional view of the C-D cut surface viewed from the arrow direction, and FIG. 3 is a cross-sectional view of the EF cut surface of the glass melting furnace shown in FIG. 1 viewed from the arrow direction.

In FIGS. 1, 2 and 3, 1 is a melt refining tank, 2 is a homogenizer tank, 3 is an outflow tank, and the melt refining tank 1 and the homogenizer tank 2 and the homogenizer tank 2 and the outflow tank 3 are They are connected by connecting pipes 4 and 5, respectively. Reference numeral 6 denotes a charging part partition plate for partitioning the front end of the melting and refining tank to form a charging part 8, and 7 is provided in the melting part and the fining part of the melting and refining tank to form a glass flow path. It is a flow path forming partition plate. Figure 2
As shown in FIG. 5, the lower end portions 6a and 7a of the partition plates 6 and 7 are fixed to the tank bottom 20a, and the upper end portions 6b and 7b are configured to always come out above the liquid surface 14a of the molten glass 14. Further, both ends of the supply partition plate 6 are fixed to the furnace wall 20, and an opening 6c is provided in a central portion at a position not exceeding the liquid surface of the molten glass 14 (see FIG. 3). Further, one end of the flow path forming partition plate 7 is fixed to the side wall 20 as shown in the figure. A stirring propeller 11 is installed in the homogenization tank 2 so that the molten glass 14 introduced from the connection pipe 4 is sufficiently stirred. Further, the outflow tank 3 is also provided with a stirring propeller 12, and while maintaining the homogeneity of the molten glass 14 introduced from the connection pipe 5, a glass flow 17 adjusted to a temperature suitable for molding is output from the outflow nozzle 9. It is designed to be leaked.

A plurality of heaters 10 are arranged as heating means around each of the tanks, the connecting pipes, and the outflow nozzles, and the heaters 10 have the functions of the tanks near them. The temperature can be controlled to a suitable temperature. The charging unit 8 melts the glass at a temperature suitable for charging the glass raw material 13 and the melting unit following the charging unit 8 of the melting and refining tank 1 melts the glass without leaving it unmelted. Following the temperature, the refining section is controlled to a temperature such that it has a refining function for removing the gas in the glass. Further, the connection pipe 4 is controlled to a temperature for eliminating dust bubbles in the glass, the homogenization tank 2 is controlled to a temperature suitable for stirring, and the outflow tank 3 is necessary for a post-process after the glass is discharged from the furnace. The temperature is controlled to a temperature close to this temperature, and the outflow nozzle 9 is controlled to a temperature suitable for the outflow required for the subsequent process.
Further, the melting and refining tank, the connecting pipe, the partition plate, and the outflow nozzle are all made of platinum or a platinum alloy, and a heat insulating material is arranged around the heater 10 so as to cover the entire furnace (not shown). ) The structure is such that the thermal efficiency of the furnace is increased and at the same time the temperature outside the furnace is prevented from rising.

Next, the step of melting glass using the above-mentioned glass melting furnace will be specifically described with reference to FIGS.
It should be noted that the glass melted here has a component ratio of S after melting, which is used as an optical element of a camera or a video camera.
_{iO 2: 46%, BaO:} 32%, B 2 O 3: 7%, A
l ₂ O ₃ : 5%, Li ₂ O ₃ + Na ₂ O + K ₂ O: 5
%, ZnO: 4%, and other materials: 1%.

The melting and refining tank 1 except for the charging section 8 is
It is formed in a rectangular shape having a length of 400 mm, a width of 350 mm and a height of 75 mm, and when the liquid level of the molten glass 14 is 58 mm, a capacity of about 8000 cc can be obtained. Similarly, the charging unit 8 has a capacity of about 1000 cc when the height of the liquid surface is 58 mm. Homogeneous tank 2, outflow tank 3
Are made in cylindrical shape, and the stirring propellers 11 and 12 are
With the capacity of 4000cc and 10 respectively
It is configured to be 00cc. Also, the outflow nozzle 9
The inner diameter of was set to 12 mm.

The temperature of each part of the furnace is controlled at 1350 ° C. in the charging part 8, 1450 ° C. at the maximum in the melting part of the melting and refining tank 1, and near the outlet of the fining part of the melting and refining tank 1 by controlling the heater 10 individually. 1150 ° C., 11 in the homogenizer tank 2
The temperature was controlled to 50 ° C., 1100 ° C. in the outflow tank 3, and 1080 ° C. at the outlet of the outflow nozzle 9.

Regarding the flow and melting state of the glass at this time, when the glass raw material 13 is first charged into the charging section 8, the glass in the semi-molten state passes through the closing section 6c of the supply partition plate 6 in an average of 30 minutes and melts. The melted part having a maximum temperature of 1450 ° C. was sufficiently melted in about 2 hours, and then flowed to the clarification part. In the refining section, it is sufficiently defoamed until it reaches 1150 ° C. in about 2 hours, and some dust particles flow into the connection pipe 4 and disappear while flowing through the connection pipe 4, and then exit the connection pipe 4 to leave the homogenization tank 2 Upon entering, glass was obtained with no unmelted residue or bubbles. After that, the mixture was stirred in the homogenization tank 2 for an average of 2 hours to eliminate striae, and then flowed into the outflow tank 3.
In the outflow tank 3, the temperature of the glass is lowered while being agitated, gradually guided to the outflow nozzle 9, and the glass flow 17 is discharged from the outflow nozzle 9.
It leaked out next. The flow rate of the glass flow 17 was 2000 cc / hour, and a high-quality glass lump that could be sufficiently used for direct molding of an optical element and was free from unraveling, bubbles, stria, etc. was obtained.

Second Embodiment Next, another embodiment of the present invention will be specifically described with reference to FIG. FIG. 4 is a plan view of a glass melting furnace of another embodiment according to the present invention as seen from above, and has the same structure as that of the first embodiment except the installation position of the partition plate 27. In FIG. 4, 21 is a melting and refining tank, 22 is a homogenizing tank, 23 is an outflow tank, and the melting and refining tank 21 and the homogenizing tank 22 are the connecting pipes 24 and 25, respectively. It is connected. 26 partitions the front end of the melting and refining tank,
A partitioning plate for the charging part for forming the charging part 28, 27
Is a flow path forming partition plate that is provided in the melting section and the refining section of the melting and refining tank and that forms a glass flow path. As in the first embodiment, the lower ends of the partition plates 26 and 27 are fixed to the bottom of the melting and refining tank, and the upper ends have such a height that they always come out above the liquid surface of the molten glass. Further, as shown in the figure, the flow path forming partition plate 27 has a pair of which one end is connected to the side wall 30 and a pair which is connected only to the bottom of the tank and is not connected to both ends. They are arranged alternately. Further, the supply section partition plate 26 has exactly the same structure as the supply section partition plate 6 of the first embodiment. A stirring propeller 31 is installed in the homogenization tank 22 so that the molten glass introduced from the connection pipe 24 is sufficiently stirred. Further, the outflow tank 23 is also provided with a stirrer 32 so that the molten glass introduced from the connection pipe 25 can maintain the homogeneity of the molten glass and flow out the glass adjusted to a temperature suitable for molding from the outflow nozzle 29. Has become. Further, as in the case of the first embodiment, a plurality of heaters 35 are arranged as heating means around each tank, the connection pipe and the outflow nozzle, and the temperature suitable for the function of the nearby tanks in which each heater is arranged. The material of each member, the arrangement of the heat insulating material, and the like have the same configuration as in the first embodiment.

Next, the step of melting glass using the glass melting furnace shown in FIG. 4 will be specifically described. As the glass material to be melted here, raw cullet obtained by semi-melting the same glass raw material as that used in Example 1 in another furnace in advance, solidifying and then crushing to an appropriate size was used.

The melting and refining tank 21 is formed into a rectangular shape having a length and width of 135 mm and a height of 50 mm except for the charging part 28, and when the liquid level of glass is 40 mm, it is about 700 c.
The capacity of c can be obtained. The charging unit 28 has a capacity of about 100 cc when the liquid surface height is 40 mm. The homogenization tank 22 and the outflow tank 23 are each formed in a cylindrical shape, and are configured so that the capacities are 500 cc and 150 cc, respectively, with the stirring propellers 31 and 32 inserted. The inner diameter of the outflow nozzle 29 was set to 6 mm.

By controlling the heaters 35 individually, the temperature of each part is set to 1280 ° C. from the charging part of the melting and refining tank to the flow path forming partition plate from the charging part to the outlet of the melting and fining tank. , The exit part is 118
The temperature was gradually decreased so that the temperature became 0 ° C. The connection pipe 24 and the homogenization tank 22 are 1180 ° C., and the outflow tank 23 is 11
The temperature was controlled to be 00 ° C and 1080 ° C at the outlet of the outflow nozzle 29.

Regarding the flow and melting state of the glass at this time, first, when raw cullet, which is a glass material, is charged into the charging section 28, the molten glass passes through the charging section partition plate 26 and flows into the melting section in 20 minutes on average. It passed through the melt fining tank over a period of about 2 hours and 20 minutes. At this time, the glass was sufficiently dissolved and bubbles were almost completely removed. After that, the glass passed through the connection pipe 24 into the homogenizing tank 22, was stirred in the homogenizing tank 22 for an average of 1 hour and 40 minutes to remove striae, and then flowed into the outflow tank 23. In the outflow tank 23, the temperature of the glass was lowered while being stirred, gradually guided to the outflow nozzle 29, and outflowed from the tip of the outflow nozzle 29. The flow rate of the glass that flowed out was 300 cc / hour, and a high-quality glass lump that could be sufficiently used for direct molding of an optical element and was free from unraveling, bubbles, stria, etc. was obtained.

[0036]

As described above, according to the present invention, by providing the partition plate for forming the glass flow path in the melting and refining tank, the glass raw material is melted without being left unmelted or mixed with bubbles. The fining tank can be downsized, and the glass material used for direct molding of optical elements can be stably and continuously supplied.

Furthermore, by providing a charging section for charging and melting the glass raw material by partitioning one corner of the melting and refining tank with a partition plate, unmelted residue and bubbles are not generated even in a very small melting and refining tank. High quality glass material can be continuously supplied.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a glass melting furnace of the present invention.

2 is a cross-sectional view of an A-B-C-D cut surface of the glass melting furnace shown in FIG.

FIG. 3 is a cross-sectional view of an E-F cut surface of the glass melting furnace shown in FIG.

FIG. 4 is a plan view showing another embodiment of the glass melting furnace of the present invention.

[Explanation of symbols]

 1, 21 Melt refining tank 2,22 Homogeneous tank 3,23 Outflow tank 4,5 Connection pipe 6,26 Input part partition plate 7,27 Flow path formation partition plate 8,28 Input part 9 Outflow nozzle 20,30 Side wall 20a tank bottom

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mizukazu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. A tank type glass melting furnace comprising at least a charging unit for charging a glass raw material, a melting and refining tank for melting and refining glass, and an outflow nozzle for flowing out the molten glass. A glass melting furnace having therein one or a plurality of partition plates that form a glass flow path. 2. The glass melting furnace according to claim 1, wherein the height of the partition plate is higher than the height from the bottom of the melting and refining tank to the liquid surface of the glass in the melting and refining tank. 3. The partition plate is fixed to the bottom of the melting and refining tank so that the partition surface for partitioning the glass flow of the partition plate is perpendicular to the glass flow direction. The glass melting furnace according to 1. 4. The glass melting furnace according to claim 1, wherein one end of one or a plurality of partition plates is fixed to a side wall of the melting and refining tank. 5. The glass melting furnace according to claim 1, wherein a charging unit for charging the glass raw material is provided in the melting and refining tank. 6. The glass melting furnace according to claim 5, wherein the charging section is provided in the melting and refining tank by a partition plate having a hole for allowing the molten glass to pass therethrough. 7. A melting and refining tank for melting and refining glass.
A homogenizing tank that stirs the molten and clarified glass to homogenize it, and an outflow tank that stirs the homogenized glass to adjust the outflow temperature are sequentially connected by a connecting pipe, and the outflow tank is connected to the outflow nozzle. The glass melting furnace according to any one of claims 1 to 6, which further comprises a heating unit around each of the tanks, the connection pipes, and the outflow nozzle, the heating unit being capable of arbitrarily controlling the temperature.