JPH0848529A - Flow rate controller for fused optical glass - Google Patents

Abstract

PURPOSE:To minimize the useless consumption of raw material glass and to maintain the outflow rate of fused glass at a desired value by providing a fused glass outflow vessel with an overflow part, measuring the liquid level height of the fused glass and controlling an overflow rate. CONSTITUTION:This flow rate controller for the fused glass controls the flow rate of the glass in an outflow port at the time of melting the glass raw material in a melting vessel 2, bining the raw material in a bining vessel 5, discharging the fused glass from the fused glass outflow vessel 7 through an outflow pipe 8 and the outflow port and separating the glass at a desired outflow rate. The fused glass outflow vessel 7 is provided with the overflow part 9 and is provided with a measuring means 13 for continuously measuring the liquid level height of the fused glass in an overflow state and a control means 14 for controlling the increase and decrease of the charging amt. to a raw material glass charging device 11 in accordance with the tendency of change in the measured data, in order to maintain the specified liquid level of the fused glass relating to the glass flow rate at the outflow port.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to measure and control the liquid level of molten glass in a glass melting furnace of the type in which a glass raw material is melted and continuously flown out while supplying the glass raw material. The present invention relates to a molten glass flow rate control device for controlling the amount.

[0002]

2. Description of the Related Art Conventionally, in a glass melting furnace of a type in which molten glass is continuously discharged, in order to keep the amount of molten glass flowing out, the liquid level of molten glass is measured and A method of changing the supply amount of the glass raw material to the melting furnace according to the fluctuation has been widely used.

The liquid level measuring device irradiates the molten glass with radiation such as gamma rays from the outside of the furnace, and measures the decrease in the radiation passing through the molten glass to determine the thickness of the molten glass, that is, the liquid level height. A means of measuring the height was adopted.
Alternatively, as another form, there is known an apparatus that measures a product weight as a result of molten glass flowing out and supplies a glass raw material corresponding to the used glass weight at regular intervals based on the measurement result. .

In particular, in a glass melting furnace that requires a small fluctuation of the outflow amount, in order to prevent the fluctuation of the liquid level,
Flow rate control with a method that supplies more glass raw material than the outflow amount of molten glass, discards excess glass due to overflow provided at the outflow portion, and keeps the liquid level of molten glass constant related to the outflow amount of glass Devices have also been used.

[0005]

However, as described above, in the method of controlling the liquid level height by adjusting the supply amount of the raw glass, the raw material is kept until the liquid level of the molten glass reaches a desired height. Since it takes a considerable time for melting, refining, and moving to the outflow portion of the glass, it is difficult to correct the fluctuation of the liquid surface of the molten glass in a short time, particularly, fine correction in units of several mm.

In addition, using radiation such as gamma rays,
Since the liquid level measuring method of molten glass uses harmful radiation of the human body, careful handling is required and the measuring device is expensive.

Further, a method of measuring the weight of the product obtained as a result of the outflow of the molten glass and supplying a glass raw material corresponding to the weight of the glass used at regular intervals also causes the water such as water to flow out into the raw glass. The glass that contains the volatile components that do not remain in the glass, or due to the volatile components during glass melting, etc., the total weight decreases, so it is difficult to completely match the input amounts of the outflow glass and the raw glass, The expected high-precision flow rate control cannot be performed.

Further, a method of discarding excess glass by overflow and keeping the liquid level of the molten glass constant is as follows.
The molten glass is always discarded, and the raw material glass is wasted. However, in the case of glass that requires high quality, such as optical glass, the discarded glass cannot be melted again as a raw material, leading to an increase in cost.

[0009]

In the present invention, an overflow portion is provided in a molten glass outflow tank (the final stage of a continuous glass melting crucible), and a raw material glass which is larger than a glass outflow amount by a predetermined amount is supplied from a raw material glass charging port. Then, by discharging the excess glass from the overflow part, the liquid level of the molten glass is kept constant, so that the molten glass outflow amount is maintained at a desired value, and at the same time, the liquid level of the molten glass or the overflow. If the liquid level tends to rise or the overflow amount tends to increase, the feed amount of the raw glass is reduced and the liquid level tends to fall, or the overflow level increases. When the amount tends to decrease, by increasing the supply amount of raw glass,
Correction of liquid level fluctuation of molten glass in a short time, especially a few meters
The fine correction can be performed in units of m and the amount of overflow is changed according to the amount of outflow of the molten glass, so that the waste of the raw material glass is stopped to a minimum.

As means for measuring the liquid level of the molten glass, a range finder using ultrasonic waves or a range finder using a laser is used, or a platinum alloy electrode plate and a molten glass liquid level are used. By using a means for measuring the change in electric capacity between the
It can be simple and highly accurate.

Further, when the overflow flow rate is measured, the weight of the molten glass that overflows is measured to obtain the outflow glass amount, so that the measuring device can be simplified and highly accurate.

[0012]

EXAMPLES Example 1 Hereinafter, the present invention will be described based on illustrated examples. The embodiment shown in FIG. 1 best represents the features of the present invention, in which reference numeral 1 is a glass melting device, 2 is a glass melting tank (crucible) provided inside thereof, and 3 is a glass melting optical glass. (In this embodiment, SK12 is used), and the glass melting tank 2 is composed of a glass melting tank 4, a glass refining tank 5 and a glass outflow tank 7 which are communicated with each other in sequence. Is arranged, an outflow pipe 8 communicates with the bottom of the glass outflow tank 7, and an overflow section 9 is provided on one side of the upper part thereof.

The glass supplied from the glass raw material charging device 11 into the glass melting tank 4 is melted there, and then stirred in the glass refining tank 5 by the glass stirrer 6 to undergo the refining step. Next, it proceeds to the glass outflow tank 7, passes through the outflow pipe 8, and is guided to the outside from the orifice (outlet) at the lower end. In this case, the temperature of the molten glass in the outflow pipe 8 is 1180 ° C. [the viscosity of the glass is 10
^1.1 Pa · s, the inner diameter of the outflow pipe 8 is set to 6 mm, and the glass flow rate is set to 70 g / min.

The glass melting tank 2 is heated and controlled by heating means (not shown in the figure) in the glass melting apparatus 1 so that the temperature of each glass melting tank 2 becomes a predetermined temperature.

The outflow amount of the molten glass guided to the outside through the outflow pipe 8 depends on the type of glass and the temperature of the glass, but as another important factor for determining the outflow amount of the molten glass, the molten glass is Liquid level height (head)
is connected with.

Therefore, the liquid level height of the overflow portion 9 provided adjacent to the glass outflow tank 7 is measured by, for example, the ultrasonic distance sensor 13, and the liquid level height of the molten glass in the outflow tank 7 is measured. Ask for (head). The ultrasonic waves 15 emitted from the oscillating unit of the ultrasonic distance sensor 13 are reflected when they hit the liquid surface of the overflow unit 9 and return to the receiving unit of the ultrasonic distance sensor 13. The distance can be evaluated by measuring the elapsed time at this time. In the present embodiment, the ultrasonic guide pipe 16 is provided between the ultrasonic distance sensor 13 and the overflow section 9 in order to suppress the diffusion of ultrasonic waves. Further, in order to prevent the ultrasonic distance sensor from being heated and damaged due to heat rise and heat dissipation from the glass melting device, the cooling air blower 17 is provided with a cooling gas between the sensor 13 and the pipe 16. If
It is arranged so that the air is sent at a right angle to the direction of projection of ultrasonic waves.

As a result of the measurement by the sensor 13, when the reflection distance becomes smaller, that is, when the increase in the liquid level height (head) of the molten glass is detected, a signal from the control device 14 causes a signal from the glass raw material charging device 11 of the glass raw material charging device 11. The valve 12 is squeezed to reduce the amount of glass input and stop the rise of the liquid level. On the contrary, the reflection distance increases, that is, the height of the liquid surface of the molten glass (head)
When a decrease in the temperature is detected, a signal from the control device 14 causes the valve 12 to open, increasing the amount of glass input and raising the liquid level.

Thus, the liquid level of the molten glass is continuously measured. When the liquid level tends to rise, the supply amount of the raw glass is reduced, and when the liquid level tends to fall, the raw glass is lowered. By increasing the supply amount of the molten glass, it becomes possible to correct the fluctuation of the liquid surface of the molten glass in a short time, especially fine correction in units of several mm. By changing the overflow amount according to the outflow amount of the molten glass, It is possible to minimize the waste of glass. Further, by using the ultrasonic distance sensor, the liquid level of the molten glass can be measured in a non-contact manner, and the measurer is not directly affected by the infrared rays emitted from the molten glass. .

(Embodiment 2) Next, as another embodiment of the present invention, the configuration shown in FIG. 2 will be described. Here, the configuration is the same as that of the first embodiment except the distance detecting means. That is, the liquid level of the overflow 9 provided adjacent to the glass outflow tank 7 is measured by a laser range finder 18 as a measuring means, and thereby the liquid level height (head) of the molten glass is obtained. You can Here, the laser light 19 projected from the laser rangefinder 18 hits the liquid surface of the overflow 9 and is reflected by the laser rangefinder 1.
Returning to 8, the distance can be measured.

In this embodiment, in order to prevent the rise of hot air from the internal furnace of the glass melting apparatus 1 and the heating of the laser rangefinder due to heat radiation, and the introduction of outside air into the glass melting apparatus,
In order to prevent the temperature distribution in the melting device from deteriorating, a cold filter 20 that transmits laser light but blocks air from entering and exiting is provided in the distance measuring port (window).

However, when the reflection distance of the laser beam becomes small, that is, when the height of the liquid surface (head) of the molten glass is detected, a signal from the control device 14 causes a valve of the glass raw material charging device 11. Squeeze 12 to reduce the amount of glass input to stop the rise of the liquid level. Further, when the reflection distance becomes large, that is, when the decrease in the liquid level (head) of the molten glass is detected, the valve 12 of the glass raw material feeding device 11 is opened by the signal from the control device 14 to feed the glass. Increase the amount to raise the liquid level.

In this way, the liquid level of the molten glass is continuously measured. When the liquid level tends to rise, the feed amount of the raw glass is reduced, and when the liquid level tends to fall, the raw glass is lowered. By increasing the supply amount of the molten glass, it becomes possible to correct the fluctuation of the liquid surface of the molten glass within a short time, in particular, to make a fine correction in several mm, and by changing the overflow amount according to the outflow amount of the molten glass. , It has become possible to minimize the waste of raw glass. In this example,
By using a laser rangefinder, it has become possible to perform highly accurate distance measurement (distance measurement).

(Embodiment 3) Next, Embodiment 3 of the present invention will be described.
This will be specifically described with reference to FIG. Here, the same configuration as that of the second embodiment is basically shown, and in particular, the feature is that the reflection mirror 21 is provided in the distance detection portion of the second embodiment. That is, the liquid level of the overflow 9 provided adjacent to the glass outflow tank 7 is measured by the laser range finder 18 to obtain the liquid level (head) of the molten glass.
At this time, the laser light 19 emitted from the laser range finder 18 has its optical axis bent at a right angle by the reflection mirror 21 and hits the liquid surface of the overflow 9.

In this embodiment, the laser distance meter can be removed from the upper surface of the glass melting device by bending the optical axis at a right angle by the reflection mirror 21, and the laser caused by the rise of hot air and heat radiation from the glass melting device. The heating of the rangefinder can be avoided.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIG. Here, the configuration is the same as that of the first embodiment except the distance detecting means. That is, the peculiar point is that a platinum alloy electrode plate 22 is provided directly above the liquid surface of the overflow 9 from the control unit 25 of the capacitance distance meter through the lead wire 23 of the platinum alloy, and the capacitance distance meter is also provided. From the control section 25 of the above, it is electrically connected to the glass melting tank 2 through another lead wire 24 of platinum alloy. Here, since the glass in the molten state has conductivity, if the distance between the liquid surface of the molten glass and the electrode plate 22 changes, it can be detected as a difference in capacitance with a capacitance distance meter. .

However, when the distance from the electrode plate 22 to the liquid surface becomes small, that is, when the height (head) of the molten glass is detected to increase, a signal from the control unit 25 of the capacitance distance meter is sent. The signal is transmitted to the control device 14, and the signal from the control device 14 is used to squeeze the valve 12 of the glass raw material charging device 11 to reduce the amount of glass charged and stop the rise of the liquid level.
Also, the distance from the electrode plate to the liquid surface increases, that is,
When a decrease in the liquid level height (head) of the molten glass is detected, a signal from the control unit 25 of the capacitance distance meter is transmitted to the control device 14, and the signal from the control device 14 causes
The valve 12 of the glass raw material charging device 11 is opened to increase the amount of glass charged and raise the liquid level.

Thus, the liquid level of the molten glass is continuously measured. When the liquid level tends to rise, the supply amount of the raw glass is reduced, and when the liquid level tends to fall, the raw glass By increasing the supply amount of the molten glass, it becomes possible to correct the fluctuation of the liquid level of the molten glass within a short time, in particular, fine correction in units of several mm, and by changing the overflow amount according to the outflow amount of the molten glass. Now, it is possible to minimize the waste of raw glass.

In this embodiment, by using a capacitance distance meter, the liquid level height of the molten glass can be measured without contact, and the influence of infrared rays emitted from the molten glass can be measured. Since the opening of the melting device for distance measurement can be minimized without receiving it, the temperature distribution inside the melting device is less disturbed.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIG. Here, the overflow tray 10
Is connected to the weight sensor 27 through the drive shaft 26, the molten glass flowing out from the overflow portion is
A signal of the weight of the molten glass that has overflowed is transmitted from the weight sensor 27 to the weighing scale control unit 28 in the process of being sequentially accumulated in the overflow tray 10.
This weight control unit can determine the increase / decrease in the overflow per hour by differentiating the weight of the molten glass that has overflowed with respect to time.

However, when the overflow amount per hour increases, the signal from the weighing scale control unit 28 is transmitted to the control device 14, and the signal from the control device 14 causes the valve 12 of the glass raw material charging device 11 to operate. Stop the rise of the liquid level by reducing the amount of squeezing and glass input. Further, when the overflow amount per hour is reduced, the signal from the weighing scale control unit 28 is transmitted to the control device 14, and the signal from the control device 14 opens the valve 12 of the glass raw material feeding device 11 to turn on the glass. Increase the input amount to raise the liquid level.

In this way, the liquid level of the molten glass is continuously measured. When the liquid level tends to rise, the supply amount of the raw glass is reduced, and when the liquid level tends to fall, the raw glass is lowered. It is possible to correct the fluctuation of the liquid level of the molten glass within a short period of time by increasing the supply amount of, especially fine correction in units of several mm, and change the overflow amount according to the outflow amount of the molten glass. As a result, it is possible to minimize the waste of the raw material glass. If a method of determining the flow rate of the overflow by measuring the weight of the molten glass that overflows as described above, a highly accurate control result can be obtained with a simple measuring device.

In the above embodiments, S is used as the optical glass.
Although the case of using K-12 has been described, it goes without saying that the same apparatus of the present invention can be applied to other optical glasses by adjusting the melting conditions.

[0033]

The present invention has been described in detail above, and the glass at the outlet when the molten glass is discharged from the molten glass outflow tank through the outlet and the desired amount of glass is separated. In a molten glass flow rate control device for controlling the flow rate, in order to keep the liquid surface of the molten glass related to the glass flow rate of the outlet constant, an overflow portion is provided in the molten glass outflow tank, and the molten glass in the overflow state is Measuring means for continuously measuring the liquid level height, and, based on the tendency of the change of the data measured by the measuring means, since it has a control means for controlling the increase and decrease of the input amount of the raw material glass, the overflow amount By changing the amount of molten glass outflow, the waste of raw glass is minimized, the liquid surface of molten glass is kept constant, and the outflow amount of molten glass is reduced. It became possible to retain the value of Nozomu.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass melting device (furnace) 2 Glass melting tank (crucible) 3 Molten optical glass 4 Glass melting tank 5 Glass refining tank 6 Glass stirrer 7 Glass outflow tank 8 Outflow pipe 9 Overflow 10 Overflow saucer 11 Glass raw material charging device 12 Valve 13 Ultrasonic distance sensor 14 Control device 15 Ultrasonic 16 Ultrasonic guide pipe 17 Cooling air blower 18 Laser distance meter 19 Laser light 20 Cold filter 21 Reflective mirror 22 Electrode plate 23 Conductor wire 24 Conductive wire 25 Capacitance distance meter control unit 26 Drive shaft 27 Weight sensor 28 Scale controller

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

Claims (12)

[Claims] 1. A molten glass flow rate control device for controlling a glass flow rate at an outlet when a molten glass is discharged from a molten glass outflow tank through an outlet thereof to separate a desired amount of glass. In order to keep the liquid surface of the molten glass constant with respect to the glass flow rate at the outlet, an overflow section is provided in the molten glass outflow tank, and a measuring means for continuously measuring the liquid surface height of the molten glass in the overflow state. And a control means for controlling the increase and decrease of the amount of raw material glass charged based on the tendency of the change of the data measured by the measuring means. 2. A molten glass flow rate control device for controlling a glass flow rate at an outflow port when a molten glass is flown out of a molten glass outflow tank through an outflow port thereof to separate a desired outflow amount of glass, In order to keep the liquid surface of the molten glass related to the glass flow rate of the outlet constant, a measuring means for continuously measuring the overflow amount together with an overflow part provided in the molten glass outflow tank, and the measuring means A flow control device for molten glass, comprising a control means for controlling an increase and a decrease in the amount of raw material glass charged based on the tendency of the data change. 3. The molten glass flow rate control device according to claim 1, wherein the means for measuring the liquid surface height of the molten glass is a rangefinder using ultrasonic waves. 4. A range finder using ultrasonic waves is installed outside a melting device for holding a molten glass outflow tank in a required atmosphere, and a molten glass is passed through a hollow pipe that penetrates the melting device in and out. The molten glass flow rate control device according to claim 3, wherein the molten glass flow amount control device is configured to measure the liquid level height of the molten glass. 5. The cooling means for flowing a cooling gas between a distance meter using an ultrasonic wave installed outside the melting device and a hollow pipe is provided. Flow control device for molten glass. 6. The molten glass flow rate control device according to claim 1, wherein the means for measuring the liquid surface height of the molten glass is a rangefinder using a laser. 7. A laser-based rangefinder is installed outside the melting device and is configured to measure the liquid level of the molten glass through a window through which the inside of the melting device can be observed. The molten glass flow rate control device according to claim 6. 8. The molten glass flow rate control device according to claim 7, wherein the member of the window capable of observing the inside of the melting device is a cold filter. 9. The flow rate control of the molten glass according to claim 6, wherein the optical axis of the distance meter using the laser and the optical axis of the window for observing the inside of the melting device are on the same straight line. apparatus. 10. An optical axis of a distance meter using a laser and an optical axis of a window for observing the inside of the melting device are arranged such that a laser beam passes through both optical axes via a reflecting member such as a mirror or a prism. The molten glass flow rate control device according to claim 6 or 7, wherein the molten glass flow rate control device is arranged at an angle required for the above. 11. The means for measuring the liquid level of the molten glass is characterized in that it is configured to measure the change in the electric capacity between the electrode plate of platinum alloy and the liquid level of the molten glass. The flow control device for molten glass according to claim 1. 12. A means for measuring the amount of overflow comprises measuring the weight of the molten glass flowing into a container for receiving the molten glass flowing out from the overflow outlet provided in the outer periphery of the molten glass outflow tank. The molten glass flow rate control device according to claim 2, wherein the flow control device is for a molten glass.