JP2015129060A - Production method of glass material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of crack or fracture in a glass material, when producing the glass material by a containerless floating method.SOLUTION: In a production method of a glass material including a first irradiation step and a second irradiation step, a glass raw material lump 12 is heated and melted by irradiating laser light onto the floated glass raw material lump 12 to obtain molten glass, and then the molten glass is cooled to obtain the glass material. In the first irradiation step, the glass raw material lump 12 is heated and melted by irradiating laser light onto the floated glass raw material lump 12. In the second irradiation step, intensity of laser light irradiated onto the molten glass is lowered, and then irradiation of laser light is stopped.

Description

  The present invention relates to a method for producing a glass material.

  In recent years, research on a containerless floating method has been made as a method for producing a glass material. For example, in Patent Document 1, a barium titanium ferroelectric sample suspended in a gas floating furnace is irradiated with a laser beam, heated and melted, and then cooled, whereby the barium titanium ferroelectric sample is cooled to glass. Is described. Thus, in the containerless floating method, since the progress of crystallization due to contact with the wall surface of the container can be suppressed, even a material that could not be vitrified by a conventional manufacturing method using a container. It may be vitrified. Therefore, the containerless floating method is a method that should be noted as a method capable of producing a glass material having a novel composition.

JP 2006-248801 A

  For example, when trying to manufacture a large glass material by the containerless floating method, cracks or cracks may occur in the glass material.

  The main object of the present invention is to suppress the occurrence of cracks and cracks in a glass material when the glass material is produced by a containerless floating method.

  The method for producing a glass material according to the present invention comprises irradiating a suspended glass raw material lump with laser light to heat and melt the glass raw material lump to obtain molten glass, and then cooling the molten glass to obtain the glass material. It is the manufacturing method of the glass material to obtain. The manufacturing method of the glass material which concerns on this invention is equipped with a 1st irradiation process and a 2nd irradiation process. In the first irradiation step, the glass raw material lump is heated and melted by irradiating the suspended glass raw material lump with laser light. In the second irradiation step, the laser beam irradiation is stopped after the intensity of the laser beam irradiated to the molten glass is reduced.

  In the manufacturing method of the glass material which concerns on this invention, it is preferable to reduce the intensity | strength of a laser beam gradually in a 2nd irradiation process.

In the method for producing a glass material according to the present invention, the ratio (P ₂₎ of the intensity P ₂ of the laser beam immediately before stopping the irradiation of the laser beam to the intensity P ₁ of the laser beam irradiated when the glass raw material lump is heated and melted. / P ₁ ) is preferably 0.95 or less.

  In the method for producing a glass material according to the present invention, the glass raw material lump is floated and held above the molding surface by ejecting gas from a gas ejection hole opened on the molding surface of the mold. It is preferable to irradiate a laser beam and supply a preheated gas to the gas ejection holes.

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing a glass material by a containerless floating method, it can suppress that a crack and a crack arise in a glass material.

It is typical sectional drawing of the manufacturing apparatus of the glass material which concerns on 1st Embodiment. It is a schematic plan view of a part of the molding surface in the first embodiment. It is a time chart showing the intensity | strength of the laser beam in 1st Embodiment. It is a time chart showing the intensity | strength of the laser beam in the modification of 1st Embodiment. It is typical sectional drawing of the manufacturing apparatus of the glass material which concerns on 2nd Embodiment.

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  Moreover, in each drawing referred in embodiment etc., the member which has a substantially the same function shall be referred with the same code | symbol. The drawings referred to in the embodiments and the like are schematically described. A ratio of dimensions of an object drawn in a drawing may be different from a ratio of dimensions of an actual object. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

(First embodiment)
In this embodiment, a normal glass material, for example, a glass material that does not contain a network-forming oxide, and can be suitably manufactured even for a glass material having a composition that does not vitrify by a melting method using a container. Will be described. Specifically, according to the method of the present embodiment, for example, barium titanate glass material, lanthanum-niobium composite oxide glass material, lanthanum-niobium-aluminum composite oxide glass material, lanthanum-niobium-tantalum A composite oxide glass material, a lanthanum-tungsten composite oxide glass material, or the like can be suitably produced.

  FIG. 1 is a schematic cross-sectional view of a glass material manufacturing apparatus 1 according to the first embodiment. As shown in FIG. 1, the glass material manufacturing apparatus 1 includes a mold 10. The molding die 10 has a molding surface 10a. The molding surface 10a is a curved surface. Specifically, the molding surface 10a has a spherical shape.

  The molding die 10 has a gas ejection hole 10b opened in the molding surface 10a. As shown in FIG. 2, in this embodiment, a plurality of gas ejection holes 10b are provided. Specifically, the plurality of gas ejection holes 10b are arranged radially from the center of the molding surface 10a.

  In addition, the shaping | molding die 10 may be comprised with the porous body which has an open cell. In that case, the gas ejection hole 10b is constituted by continuous bubbles.

  The gas ejection hole 10b is connected to a gas supply mechanism 11 such as a gas cylinder. Gas is supplied from the gas supply mechanism 11 to the molding surface 10a via the gas ejection hole 10b.

  The type of gas is not particularly limited. The gas may be, for example, air or oxygen, or an inert gas such as nitrogen gas, argon gas, or helium gas.

  When manufacturing a glass material using the manufacturing apparatus 1, first, the glass raw material lump 12 is arrange | positioned on the molding surface 10a. The glass raw material lump 12 may be, for example, a glass material raw material powder integrated by press molding or the like. The glass raw material lump 12 may be, for example, a sintered body obtained by integrating glass raw material powders by press molding or the like and sintering them. Moreover, the glass raw material lump 12 may be an aggregate of crystals having a composition equivalent to the target glass composition, for example.

  The shape of the glass raw material lump 12 is not particularly limited. The glass raw material block 12 may be, for example, a lens shape, a spherical shape, a cylindrical shape, a polygonal column shape, a rectangular parallelepiped shape, an elliptical shape, or the like.

  Next, the glass raw material block 12 is floated on the molding surface 10a by ejecting gas from the gas ejection holes 10b. That is, the glass raw material lump 12 is held in a state where the glass raw material lump 12 is not in contact with the molding surface 10a. In this state, the glass material block 12 is irradiated with laser light from the laser light irradiation device 13. Thereby, the glass raw material lump 12 is heated and melted to be vitrified to obtain molten glass. Thereafter, the glass material can be obtained by cooling the molten glass. In the step of heating and melting the glass raw material lump 12 and the step of cooling until the temperature of the molten glass and further the glass material becomes at least the softening point or less, at least gas ejection is continued, and the glass raw material lump 12 and the molten glass Or it is preferable to suppress that a glass material and the molding surface 10a contact.

As shown in FIG. 3, in this embodiment, specifically, first, the glass raw material lump 12 is heated and melted by irradiating the suspended glass raw material lump 12 with laser light (first irradiation step). . In the first irradiation step, the intensity of the laser beam to adjust the output of the laser beam irradiation device 13 so that P _1. The laser beam having the intensity P ₁ is irradiated until the time T ₁ when the glass raw material block 12 is completely heated and melted. Time T ₁ is or strength P ₁ of the laser beam can be appropriately set by the size of the glass raw material lump 12. Time _{T 1,} for example, may be 10 seconds to 30 seconds. Intensity P ₁ can be set as appropriate by the size of the laser light source of the type and the glass raw material lump 12.

Next, by reducing the output of the laser beam irradiation device 13, the intensity of the laser beam irradiated on the molten glass is decreased, and then the laser beam irradiation is stopped (second irradiation step). In the present embodiment, specifically, the intensity of the laser light is decreased until the intensity of the laser light becomes P ₂ lower than P ₁ . Intensity P _2, in the period in which irradiating a laser beam intensity P ₂ in the molten glass, is a strength that the temperature of the molten glass is not lower than the softening temperature. The ratio (P ₂ / P ₁ ) of the laser beam intensity P ₂ immediately before stopping the laser beam irradiation to the laser beam intensity P ₁ irradiated when the glass raw material mass 12 is heated and melted is 0.95 or less. Preferably, it is 0.9 or less, more preferably 0.8 or less.

In the present embodiment, the intensity of the laser light is gradually decreased from P ₁ to P ₂ during the time T ₁ to T ₂ . The period (T ₂ −T ₁ ) from time T ₁ to T ₂ is preferably about 3 seconds to 10 seconds, for example. However, the present invention is not limited to this. For example, it may be a stretch reduce the intensity of the laser beam from the intensity P ₁ to P _2.

  As a result of diligent research, the inventor has surprisingly reduced the intensity of the laser light applied to the molten glass and then stopped the laser light irradiation, for example, when the glass material is large. It was also found that cracks and cracks can be suppressed in the produced glass material. In general, it is considered important to reduce the cooling rate in the temperature range from near the softening temperature to near the strain point in order to suppress the occurrence of cracks and cracks in the manufactured glass material. Therefore, it is considered that the cooling rate at a temperature higher than the softening temperature does not affect cracks and cracks. For this reason, this fact was very surprising for those skilled in the art.

  The reason why it is possible to suppress the occurrence of cracks and cracks in the manufactured glass material by stopping the irradiation of the laser light after once reducing the intensity of the laser light irradiating the molten glass is not clear. The following reasons can be considered. That is, the maximum value of the temperature difference between the central portion and the outer portion of the glass material can be reduced by once stopping the irradiation of the laser light after once reducing the intensity of the laser light irradiating the molten glass. . For this reason, the internal stress which arises between the center part and outer part of a glass material can be made small. Therefore, it is considered that cracks and cracks are less likely to occur in the glass material.

From the viewpoint of more effectively suppressing the occurrence of cracks and cracks in the manufactured glass material, it is preferable to gradually reduce the intensity of the laser beam in the second irradiation step. Further, as shown in FIG. 4, after is gradually decreased the intensity of the laser light to P _2, it is preferable to provide a period for holding the intensity of the laser beam at P _2. The period (T ₃ -T ₂ ) is preferably 3 seconds or longer, and more preferably 5 seconds or longer. However, if the period (T ₃ -T ₂ ) is too long, the time required for manufacturing the glass material becomes long. Therefore, the period (T ₃ -T ₂ ) is preferably 20 seconds or shorter, and more preferably 10 seconds or shorter.

The ratio (P ₂ / P ₁ ) is preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. The intensity of the laser beam may be gradually decreased until the intensity of the laser beam becomes zero. That is, P ₂ = 0 may be set.

  It is preferable to provide a heating mechanism 14 between the gas supply mechanism 11 and the gas ejection hole 10b to supply preheated gas to the gas ejection hole 10b. By doing so, the cooling rate of the outer part of glass material can be made low. Therefore, the maximum value of the temperature difference between the central portion and the outer portion of the glass material can be further reduced. The temperature of the gas supplied to the gas ejection hole 10b is preferably 100 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 400 ° C. or higher. However, if the temperature of the gas supplied to the gas ejection hole 10b is too high, the temperature of the mold 10 may become too high. If the temperature of the mold 10 becomes too high, the molten glass may be fused to the molding surface 10a and crystals may be generated in the glass material. Therefore, the temperature of the gas supplied to the gas ejection hole 10b is preferably 1000 ° C. or less, and more preferably 900 ° C. or less.

  Hereinafter, other examples of preferred embodiments of the present invention will be described. In the following description, members having substantially the same functions as those of the first embodiment are referred to by the same reference numerals, and description thereof is omitted.

(Second Embodiment)
FIG. 5 is a schematic cross-sectional view of the glass material manufacturing apparatus 2 according to the second embodiment.

  In the first embodiment, the example in which the plurality of gas ejection holes 10b are opened on the molding surface 10a has been described. However, the present invention is not limited to this configuration. For example, like the glass material manufacturing apparatus 2 shown in FIG. 5, one gas ejection hole 10 b opened at the center of the molding surface 10 a may be provided. Even in this case, as in the first embodiment, the glass material is cracked or broken by once stopping the irradiation of the laser light after once reducing the intensity of the laser light irradiating the molten glass. Can be suppressed, and the glass material can be manufactured stably.

DESCRIPTION OF SYMBOLS 1, 2: Manufacturing apparatus 10 of glass material 10: Mold 10a: Molding surface 10b: Gas ejection hole 11: Gas supply mechanism 12: Glass raw material lump 13: Laser beam irradiation apparatus 14: Heating mechanism

Claims (4)

A glass material manufacturing method for obtaining a glass material by cooling the molten glass after obtaining the molten glass by heating and melting the glass material lump by irradiating laser light to the suspended glass material lump, ,
A first irradiation step of heating and melting the glass raw material lump by irradiating the suspended glass raw material lump with laser light;
A second irradiation step of stopping irradiation of the laser light after reducing the intensity of the laser light irradiating the molten glass;
A method for producing a glass material.   The method for producing a glass material according to claim 1, wherein in the second irradiation step, the intensity of the laser beam is gradually reduced. The ratio (P ₂ / P ₁ ) of the intensity P ₂ of the laser beam immediately before stopping the irradiation of the laser beam to the intensity P ₁ of the laser beam irradiated when the glass raw material mass is heated and melted is 0.95. The manufacturing method of the glass material of Claim 1 or 2 which is the following. By irradiating the glass raw material lump with the laser beam in a state where the glass raw material lump is suspended and held above the molding surface by jetting gas from a gas ejection hole opened on the molding surface of the mold,
The manufacturing method of the glass material as described in any one of Claims 1-3 which supplies the preheated gas to the said gas ejection hole.

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