JP2024068628A - Method and device for manufacturing glass material - Google Patents

Abstract

To provide a method for manufacturing a glass material that can suppress devitrification of a glass material that is acquired with a container-less floating method.SOLUTION: A method for manufacturing a glass material includes the steps of: heating a glass raw material lump while floating the glass raw material lump and acquiring molten glass in which the glass raw material lump is heated and melt; and cooling the molten glass and acquiring a glass material. In the step of heating the glass raw material lump, the glass raw material lump is heated while the glass raw material lump floats and a gas is jetted and in the step of cooling the molten glass, vibration imparting means imparts vibration to the molten glass while being cooled.SELECTED DRAWING: None

Description

The present invention relates to a method and apparatus for manufacturing glass material using the containerless levitation method.

In recent years, research has been conducted on the containerless levitation method as a method for manufacturing glass materials. For example, Patent Document 1 describes a method for vitrifying a barium-titanium ferroelectric sample by irradiating a barium-titanium ferroelectric sample levitated in a gas levitation furnace with laser light to heat and melt the sample, and then cooling the sample. In this way, the containerless levitation method can suppress the progression of crystallization caused by contact with the wall of the container, so that even materials that could not be vitrified using conventional manufacturing methods using containers can sometimes be vitrified. Therefore, the containerless levitation method is worthy of attention as a method that can manufacture glass materials with new compositions.

JP 2006-248801 A

In the containerless levitation method described in Patent Document 1, during the cooling process of the molten glass obtained by heating and melting the glass raw material lump, the molten glass may come into contact with the forming surface of the manufacturing equipment during cooling. When the molten glass comes into contact with the forming surface during cooling, crystallization may progress in that area, causing the resulting glass material to devitrify.

The object of the present invention is to provide a method and apparatus for manufacturing glass material that can suppress devitrification of glass material obtained by the containerless levitation method.

We will explain various aspects of the glass material manufacturing method and glass material manufacturing device that solve the above problems.

The method for producing a glass material according to aspect 1 of the present invention includes a step of obtaining molten glass by heating a glass raw material lump in a floating state and heating and melting the glass raw material lump, and a step of obtaining a glass material by cooling the molten glass, characterized in that in the step of heating the glass raw material lump, the glass raw material lump is heated in a floating state while gas is ejected, and in the step of cooling the molten glass, vibration is applied to the molten glass during cooling by a vibration applying means.

In the method for manufacturing a glass material of aspect 2, in aspect 1, it is preferable that the vibration frequency of the vibration imparting means is 1 Hz or more and less than 100 Hz.

In the method for producing a glass material of aspect 3, in aspect 1 or aspect 2, it is preferable that the vibration imparting means is a means for imparting vibration to the molten glass during cooling by intermittently ejecting gas.

In the method for producing a glass material of aspect 4, in aspect 3, when the gas is intermittently ejected, it is preferable that the gas is ejected intermittently through a solenoid valve that allows the gas to pass intermittently.

In the method for producing a glass material of aspect 5, in any one of aspects 1 to 4, when the glass raw material lump is heated, it is preferable to heat the glass raw material lump by irradiating the glass raw material lump with laser light.

The glass material manufacturing apparatus according to aspect 6 of the present invention is an apparatus for manufacturing a glass material by heating a glass raw material lump while it is suspended in a gas, heating and melting the glass raw material lump to obtain molten glass, and then cooling the molten glass to manufacture a glass material, and is characterized in that it is equipped with a molding die having a molding surface formed with a plurality of gas ejection holes for suspending the glass raw material lump in a gas, a gas supply mechanism for supplying gas to the gas ejection holes, a heating means for heating the glass raw material lump, and a vibration imparting means for imparting vibration to the molten glass during cooling.

In the glass material manufacturing apparatus of aspect 7, in aspect 6, it is preferable that the vibration imparting means is an electromagnetic valve.

In the glass material manufacturing apparatus of aspect 8, in aspect 6 or aspect 7, it is preferable that the heating means is a laser light irradiation device.

The present invention provides a method and apparatus for producing glass material that can suppress devitrification of glass material obtained by the containerless levitation method.

FIG. 1 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to an embodiment of the present invention. FIG. 2 is a schematic plan view of a portion of the molding surface of the glass material manufacturing apparatus of FIG. FIG. 3A is a schematic cross-sectional view showing a state in which the solenoid valve is open, and FIG. 3B is a schematic cross-sectional view showing a state in which the solenoid valve is opened and closed. FIG. 4 is a diagram showing a first example of a time chart of gas flow rates in a method for producing a glass material according to an embodiment of the present invention. FIG. 5 is a diagram showing a second example of a time chart of gas flow rates in a method for producing a glass material according to an embodiment of the present invention. FIG. 6 is a diagram showing a third example of a time chart of gas flow rates in a method for manufacturing a glass material according to an embodiment of the present invention.

The following describes preferred embodiments. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

The method for producing glass material according to the present invention is a method for producing glass material by a containerless levitation method. The containerless levitation method can produce glass material having a composition that cannot be vitrified by a melting method using a container, for example.

Specifically, the containerless levitation method can be used to suitably produce barium titanate-based glass materials, lanthanum-niobium complex oxide-based glass materials, lanthanum-tungsten complex oxide-based glass materials, lanthanum-titanium complex oxide-based glass materials, lanthanum-tantalum complex oxide-based glass materials, lanthanum-gallium complex oxide-based glass materials, lanthanum-aluminum complex oxide-based glass materials, lanthanum-boron complex oxide-based glass materials, terbium-boron complex oxide-based glass materials, europium-boron complex oxide-based glass materials, aluminum-silicon complex oxide-based glass materials, tantalum-aluminum complex oxide-based glass materials, etc.

Hereinafter, we will first explain an example of a manufacturing apparatus used in the manufacturing method of the glass material of the present invention.

(Glass material manufacturing equipment)
1 is a schematic cross-sectional view showing a glass material manufacturing apparatus used in a glass material manufacturing method according to an embodiment of the present invention. The glass material manufacturing apparatus 1 is an apparatus for manufacturing a glass material by heating a glass raw material lump in a state of being suspended by a gas, heating and melting the glass raw material lump to obtain molten glass, and then cooling the molten glass to manufacture a glass material, and is equipped with a molding die 2 having a molding surface 2a on which a plurality of gas ejection holes 2b are formed for suspending the glass raw material lump as a levitation object 4 by gas, a gas supply mechanism 3 for supplying gas to the gas ejection holes 2b, a heating means for heating the glass raw material lump, and a vibration imparting means for imparting vibration to the molten glass during cooling.

As shown in FIG. 1, the glass material manufacturing apparatus 1 has a molding die 2. The molding die 2 has a molding surface 2a and a plurality of gas ejection holes 2b opening on the molding surface 2a. The molding surface 2a is a curved surface. Specifically, the molding surface 2a is spherical.

The radius of curvature of the forming surface 2a is preferably adjusted to match the target glass size. Specifically, when the diameter of the target glass material is x (mm) and the radius of curvature of the forming surface 2a is y (mm), it is preferable that x<y<5x, and it is more preferable that 1.5x<y<4x. In other words, the radius of curvature y of the forming surface 2a is preferably 1 time or more, more preferably 1.5 times or more, and preferably 5 times or less, and more preferably 4 times or less, of the diameter x of the glass material.

The mold 2 has gas outlets 2b that open to the molding surface 2a. As shown in FIG. 2, the glass material manufacturing apparatus 1 is provided with a plurality of gas outlets 2b. Specifically, the plurality of gas outlets 2b are arranged radially from the center of the molding surface 2a.

The mold 2 may be made of a porous material having continuous pores. In this case, the gas ejection holes 2b are made of continuous pores.

The gas outlet 2b is connected to a gas supply mechanism 3 such as a gas cylinder. Gas is supplied from the gas supply mechanism 3 to the molding surface 2a via the gas outlet 2b. This allows the floating object 4, such as a lump of glass raw material, to be floated.

The type of gas is not particularly limited. For example, the gas may be air or oxygen, a reducing gas such as a nitrogen/hydrogen mixed gas, or an inert gas such as nitrogen gas, argon gas, or helium gas.

The vibration imparting means for imparting vibration to the molten glass during cooling is preferably a solenoid valve. In the glass material manufacturing apparatus 1 of this embodiment, as shown in FIG. 1, a solenoid valve 10 is provided between the gas supply mechanism 3 and the gas outlet 2b. In addition, a pulse generator 6 for sending a pulse signal is connected to the solenoid valve 10.

When the switch of the pulse generator 6 is off, the solenoid valve 10 is open. Therefore, in this case, the gas supplied from the gas supply mechanism 3 passes through the solenoid valve 10 as is and is ejected from the gas ejection hole 2b at the set flow rate.

On the other hand, when the switch of the pulse generator 6 is on, a pulse signal is sent to the solenoid valve 10, which opens and closes. By opening and closing this solenoid valve 10, the gas supplied from the gas supply mechanism 3 passes through the solenoid valve 10 intermittently. This allows the gas that has passed through the solenoid valve 10 to be intermittently ejected from the gas ejection hole 2b.

Next, an example of a method for manufacturing glass material using the glass material manufacturing device 1 will be described.

(Method of manufacturing glass material)
First, a glass frit lump as a floating object 4 is floated on the molding surface 2a by ejecting gas from the gas ejection holes 2b opening on the molding surface 2a of the mold 2. That is, the glass frit lump as a floating object 4 is held in a state where the glass frit lump is not in contact with the molding surface 2a. In this specification, the floating object 4 may refer to molten glass obtained by heating and melting the glass frit lump, in addition to the glass frit lump.

Examples of glass raw material chunks include those obtained by integrating raw material powders of glass material by press molding or the like, sintered bodies obtained by integrating raw material powders of glass material by press molding or the like and then sintering them, and aggregates of crystals having a composition equivalent to the target glass composition. In this embodiment, the shape of the glass raw material chunks is not particularly limited, and can be, for example, lenticular, spherical, cylindrical, polygonal prism, rectangular, ellipsoidal, etc.

Next, while the glass raw material lump as the levitation object 4 is in a levitated state, the glass raw material lump is heated using a heating means. The heating means is preferably a laser light irradiation device 5. In other words, it is preferable to heat the glass raw material lump by irradiating it with a laser light from the laser light irradiation device 5. In this way, the glass raw material lump is heated and melted to obtain molten glass (melt).

The pulse generator 6 is turned off and the solenoid valve 10 is kept open from the time the glass raw material lump is floated to the time the molten glass is obtained. In other words, from the time the glass raw material lump is floated to the time the molten glass is obtained, the glass raw material lump is heated in a floating state while gas is continuously ejected. Note that, as will be explained in the gas flow rate time chart described later, the gas flow rate itself may be changed when gas is continuously ejected.

Next, the molten glass is cooled in a floating state to obtain a glass material. In the process of cooling the molten glass, the switch of the pulse generator 6 is turned on to send a pulse signal to the solenoid valve 10, which opens and closes the solenoid valve 10. By opening and closing the solenoid valve 10, the gas supplied from the gas supply mechanism 3 passes through the solenoid valve 10 intermittently. This allows the gas that has passed through the solenoid valve 10 to be intermittently ejected from the gas ejection hole 2b, and the molten glass being cooled can be vibrated. In this specification, "molten glass being cooled" refers to glass or glass melt (molten glass) that is higher than the crystallization temperature.

In the method for manufacturing a glass material of this embodiment, vibrations can be applied to the molten glass being cooled during the cooling process, so even if the molten glass comes into contact with the molding surface 2a during cooling, it can be quickly removed. This shortens the time that the molten glass is in contact with the molding surface 2a, and prevents crystallization from progressing in that area. Therefore, according to the method for manufacturing a glass material of this embodiment, devitrification of the resulting glass material can be suppressed.

In this embodiment, the intermittent gas ejection is performed only in the cooling process. In the heating process, if the glass raw material lump is heated while gas is ejected intermittently, the floating of the molten glass is likely to become unstable, making it difficult to stably manufacture the glass material. In contrast, in this embodiment, as described above, the glass raw material lump is heated in a floating state while gas is continuously ejected, so that the floating of the molten glass can be stabilized and the glass material can be manufactured more stably.

Next, we will explain the details of the solenoid valve 10 used in this embodiment.

Figure 3(a) is a schematic cross-sectional view showing the solenoid valve in an open state, and Figure 3(b) is a schematic cross-sectional view showing the solenoid valve in an open and closed state.

As shown in Figures 3(a) and 3(b), the solenoid valve 10 is a poppet type valve. The solenoid valve 10 includes a valve body 11 and a valve seat 12. In this solenoid valve 10, the valve body 11 is driven in a direction perpendicular to the valve seat 12 to open and close the gas flow path.

As shown in FIG. 3(a), when the solenoid valve 10 is open, gas supplied from the gas supply mechanism 3 passes through the solenoid valve 10 and is ejected from the gas ejection hole 2b at the set flow rate. On the other hand, as shown in FIG. 3(b), when a pulse signal is sent to the solenoid valve 10, the valve body 11 moves up and down, opening and closing the solenoid valve 10. This allows gas passing through the solenoid valve 10 to be ejected intermittently from the gas ejection hole 2b.

In this way, when gas is intermittently ejected by opening and closing the solenoid valve 10, the gas that was accumulated when the solenoid valve 10 was closed is ejected forcefully when the solenoid valve 10 is opened. Therefore, according to the method of ejecting gas intermittently through the solenoid valve 10 that allows gas to pass intermittently, even if the molten glass being cooled comes into contact with the molding surface 2a, it can be reliably removed by the gas ejected forcefully when the solenoid valve 10 is opened, and devitrification of the resulting glass material can be more reliably suppressed.

When opening and closing the solenoid valve 10, the time interval during which the solenoid valve 10 is open and the time interval during which the solenoid valve 10 is closed may be the same or different. However, from the viewpoint of opening and closing the solenoid valve 10 more easily, it is desirable that the time interval during which the solenoid valve 10 is open and the time interval during which the solenoid valve 10 is closed be the same. For example, it is preferable that the time interval during which the solenoid valve 10 is open is 0.05 seconds, and the time interval during which the solenoid valve 10 is closed is 0.05 seconds.

Also, if the time that the solenoid valve 10 is closed is short (i.e., if the pulse frequency is high), the solenoid valve 10 opens before all the gas in the connection between the solenoid valve 10 and the gas outlet 2b (e.g., gas pipe) is ejected from the gas outlet 2b, and the next gas is supplied from the gas supply mechanism 3. In other words, the next gas is supplied before the gas flow rate ejected from the gas outlet 2b becomes zero, so that gas with varying gas flow rates is ejected from the gas outlet 2b. This makes it possible to more reliably keep the molten glass floating during cooling. Alternatively, the solenoid valve 10 may be designed so that it does not close completely, so that the gas flow rate does not become zero.

When opening and closing the solenoid valve 10, the pulse frequency is preferably 1 Hz or more, more preferably 10 Hz or more, even more preferably 25 Hz or more, particularly preferably 40 Hz or more, and preferably less than 100 Hz, more preferably 80 Hz or less, even more preferably 70 Hz or less, particularly preferably 60 Hz or less. When the pulse frequency is equal to or greater than the lower limit, it is possible to make it more difficult for the molten glass to come into contact with the molding surface 2a during cooling. Even if the molten glass comes into contact with the molding surface 2a during cooling, it can be removed more reliably, and the devitrification of the resulting glass material can be more reliably suppressed. Also, when the pulse frequency is equal to or greater than the upper limit, the strength of the gas flow rate may be too small, and the molten glass during cooling may not be sufficiently vibrated. Therefore, by setting the pulse frequency to the upper limit or less than the upper limit, even if the molten glass comes into contact with the molding surface 2a during cooling, it can be removed more reliably, and the devitrification of the resulting glass material can be more reliably suppressed.

The solenoid valve 10 may be a valve other than a poppet type valve and is not particularly limited.

Below, referring to Figures 4 to 6, first to third examples of time charts of gas flow rates in the glass material manufacturing method of the present invention will be described. In the first to third examples, first, the switch of the pulse generator 6 is turned off and the solenoid valve 10 is left open. In this state, the gas supplied from the gas supply mechanism 3 is ejected from the gas ejection holes 2b to levitate the glass raw material lump on the molding surface 2a. Next, while the glass raw material lump is in a levitated state, a laser beam is irradiated from the laser beam irradiation device 5. This heats and melts the glass raw material lump to obtain molten glass (melt). Next, while the molten glass is in a levitated state, the irradiation of the laser beam is stopped and the glass raw material lump is cooled to obtain a glass material.

In the first example, as shown in FIG. 4, the gas is continuously ejected while the gas flow rate is kept constant from the start of the laser light irradiation (laser ON) until the molten glass is obtained. In the first example, the laser light irradiation is stopped (laser OFF), and the pulse generator 6 is switched on to send a pulse signal to the solenoid valve 10 to open and close the solenoid valve 10. At this time, as shown in FIG. 4, the gas flow rate is periodically increased and decreased by opening and closing the solenoid valve 10. For example, if the set gas flow rate is "10", the gas flow rate is increased and decreased to "8" when the solenoid valve 10 is closed and to "12" when the solenoid valve 10 is open, and this is increased and decreased so as to be repeated periodically. This makes it more difficult for the molten glass to come into contact with the molding surface 2a during cooling, and even if the molten glass comes into contact with the molding surface 2a during cooling, it can be more reliably removed. Therefore, devitrification of the obtained glass material can be more reliably suppressed.

The set gas flow rate depends on the type and size of the glass raw material lump, but can be, for example, 5 L/min or more and 20 L/min or less. The minimum gas flow rate when the solenoid valve 10 is closed can be, for example, 0.8 to 0.95 times the set flow rate. The maximum gas flow rate when the solenoid valve 10 is open can be, for example, 1.05 to 1.2 times the set flow rate.

In the second example, as shown in FIG. 5, gas is supplied at a set flow rate until a certain time has elapsed since the irradiation of the laser light is stopped (laser OFF), and then the pulse generator 6 is switched on to intermittently eject the gas. All other points are the same as in the first example. As in the second example, when the molten glass is cooled by stopping the irradiation of the laser light, if the temperature is equal to or higher than the crystallization temperature of the glass, the gas may be ejected intermittently after the molten glass begins to solidify by cooling.

In the third example, as shown in FIG. 6, after the start of laser light irradiation (laser ON), the gas flow rate is gradually increased until the glass raw material lump begins to be heated and melted. Then, after the glass raw material lump begins to be heated and melted, gas is continuously ejected while keeping the gas flow rate constant until the glass raw material lump is heated and melted to obtain molten glass. Other points are the same as in the first example. As in the third example, in the process of heating the glass raw material lump, it is sufficient to suspend the glass raw material lump while continuously ejecting gas, and the gas flow rate itself may be changed.

In the above embodiment, the gas is intermittently ejected by opening and closing the solenoid valve 10 to impart vibration to the molten glass during cooling. However, in the present invention, the molten glass may be vibrated by other vibration imparting means, and is not particularly limited.

The vibration imparting means may be, for example, a method of intermittently ejecting gas using a rotating drum to impart vibration to the molten glass during cooling. The rotating drum may be, for example, one in which a plurality of gas flow paths are formed, and in which a plurality of gas flow paths, gas inlet holes, and gas outlet holes are arranged such that, as the rotating drum rotates, a state in which one of the plurality of gas flow paths is connected to the gas inlet hole and the gas outlet hole and a state in which it is not connected are repeated. By constructing the rotating drum in this way, gas can be ejected intermittently.

The vibration imparting means may be a method of imparting vibration to the molten glass during cooling by applying ultrasonic waves to the mold from which the gas is ejected, or a method of imparting vibration to the mold itself using an air or motor-driven vibrator.

The vibration frequency of the vibration means is preferably 1 Hz or more, more preferably 10 Hz or more, even more preferably 25 Hz or more, particularly preferably 40 Hz or more, and preferably less than 100 Hz, more preferably 80 Hz or less, even more preferably 70 Hz or less, particularly preferably 60 Hz or less. When the vibration frequency of the vibration means is equal to or greater than the lower limit, it is possible to make it more difficult for the molten glass to come into contact with the molding surface 2a during cooling. Even if the molten glass comes into contact with the molding surface 2a during cooling, it can be removed more reliably, and the devitrification of the resulting glass material can be more reliably suppressed. When the vibration frequency of the vibration means is equal to or greater than the upper limit, it becomes close to a continuous wave, and the molten glass during cooling may not be able to be sufficiently vibrated. Therefore, by making the vibration frequency of the vibration means equal to or less than the upper limit, even if the molten glass comes into contact with the molding surface 2a during cooling, it can be more reliably removed, and the devitrification of the resulting glass material can be more reliably suppressed.

The present invention will be described below based on examples, but the present invention is not limited to these examples.

Table 1 shows Examples 1 to 3 of the present invention and Comparative Examples 1 to 3.

Examples 1 to 3 were prepared as follows. First, raw materials were mixed to obtain the glass composition shown in Table 1. Next, 0.3 g to 0.6 g of the mixed raw materials were press-molded and sintered at 900°C to 1100°C for 3 to 12 hours to produce glass raw material blocks.

Next, the obtained glass raw material lump was used to prepare a roughly spherical glass material with a diameter of about 5 mm to 7 mm by a containerless levitation method using a glass material manufacturing apparatus 1 according to FIG. 1. One to four 100W _CO2 laser oscillators were used as the heat source. The gas flow rate was in the range of 1 L/min to 15 L/min. Specifically, as shown in FIG. 4, from the start of the laser light irradiation to the time when the molten glass was obtained, the gas was continuously ejected while the gas flow rate was kept constant at 8 L/min to 12 L/min. Next, the laser light irradiation was stopped and the glass material was cooled to obtain a glass material. At this time, the laser light irradiation was stopped and the switch of the pulse generator 6 was turned on to send a 50 Hz pulse signal to the solenoid valve 10 to open and close the solenoid valve 10. Thus, in Examples 1 to 3, vibration was applied to the molten glass during cooling by a vibration applying means that intermittently ejects gas.

Using the above manufacturing method, 10 lots of glass material with the same composition were produced and the vitrification rate was confirmed. Among the 10 lots, those with a vitrification rate of 90% or more were rated A, those with a vitrification rate of 70% or more but less than 90% were rated B, and those with a vitrification rate of less than 70% were rated C.

For Comparative Examples 1 to 3, glass materials were produced in the same manner as in Examples 1 to 3, except that no vibration imparting means was used.

As shown in Table 1, the glass materials of Examples 1 to 3 had a vitrification rate of 90% or more. On the other hand, the glass materials of Comparative Examples 1 to 3 had a vitrification rate of less than 90%.

Reference Signs List 1... Glass material manufacturing apparatus 2... Forming mold 2a... Forming surface 2b... Gas jet hole 3... Gas supply mechanism 4... Levitation object 5... Laser light irradiation device 6... Pulse generator 10... Solenoid valve 11... Valve body 12... Valve seat

Claims (8)

a step of heating the glass raw material lump in a floating state to obtain molten glass by heating and melting the glass raw material lump;
cooling the molten glass to obtain a glass material;
Equipped with
In the step of heating the glass raw material lump, the glass raw material lump is heated in a floating state while a gas is ejected,
The method for producing a glass material, wherein in the step of cooling the molten glass, vibration is applied to the molten glass being cooled by a vibration applying means. The method for manufacturing a glass material according to claim 1, wherein the vibration frequency of the vibration applying means is 1 Hz or more and less than 100 Hz. The method for manufacturing a glass material according to claim 1 or 2, wherein the vibration imparting means is a means for imparting vibration to the molten glass during cooling by intermittently ejecting gas. The method for manufacturing a glass material according to claim 3, wherein the gas is intermittently ejected through an electromagnetic valve that allows the gas to pass intermittently. The method for manufacturing a glass material according to claim 1 or 2, wherein the glass raw material lump is heated by irradiating the glass raw material lump with a laser beam. An apparatus for producing a glass material by heating a glass raw material lump in a state where the glass raw material lump is suspended in a gas, thereby obtaining molten glass by heating and melting the glass raw material lump, and then cooling the molten glass, comprising:
a molding die having a molding surface formed with a plurality of gas ejection holes for suspending the glass raw material lump by gas;
a gas supply mechanism for supplying gas to the gas nozzle;
A heating means for heating the glass raw material lump;
a vibration imparting means for imparting vibration to the molten glass during cooling;
An apparatus for manufacturing a glass material comprising: The glass material manufacturing device according to claim 6, wherein the vibration applying means is an electromagnetic valve. The glass material manufacturing apparatus according to claim 6 or 7, wherein the heating means is a laser light irradiation device.

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