Holding member, glass manufacturing apparatus using same, and glass manufacturing method

Abstract

The present invention is a holding member used in a glass manufacturing device in which glass is manufactured by cooling a heat-melted glass raw material that floats on a gas, wherein the holding member has a gas injection surface having a plurality of injection ports for injecting a gas. The gas injection surface has a first region having first injection ports, which constitute a portion of the plurality of injection ports, and a second region having second injection ports different from the first injection ports from among the plurality of injection ports. The first region is positioned on the inner side of the second region when the gas injection surface is viewed in top view. The per-unit area of the injection ports of the first region is smaller than the per-unit area of the injection ports of the second region. The per-unit area of the injection ports of the first region is the ratio of the total of the cross-sectional areas of the first injection ports relative to the area of the first region when the gas injection surface is viewed in top view, and the per-unit area of the injection ports of the second region is the ratio of the total of the cross-sectional areas of the second injection ports relative to the area of the second region when the gas injection surface is viewed in top view.

Description

[Technical Field]

[0001] The present invention relates to a holding member, a glass manufacturing apparatus using the same, and a glass manufacturing method. This invention claims priority to Japanese Patent Application No. 2020-202124, filed on December 4, 2020, and the contents of that application are incorporated by reference into this application in designated states where incorporation by reference of documents is permitted. [Background technology]

[0002] For example, Patent Document 1 discloses a method for manufacturing optical glass using a laser levitation furnace. In such a laser levitation furnace, it is required to stably levitate the glass sample with a levitation gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-196236 Summary of the Invention

[0004] A first aspect of the present invention is a holding member used in a glass manufacturing apparatus that produces glass by cooling heated and melted glass raw material suspended by a gas, the holding member having a gas injection surface with a plurality of injection ports for injecting the gas, the gas injection surface having a first region having first injection ports that are some of the plurality of injection ports, and a second region having second injection ports different from the first injection ports among the plurality of injection ports, the first region being located inside the second region in a top view of the gas injection surface, the area of ​​the injection ports per unit area of ​​the first region being smaller than the area of ​​the injection ports per unit area of ​​the second region, the area of ​​the injection ports per unit area of ​​the first region being a ratio of a sum of cross-sectional areas of the first injection ports to an area of ​​the first region when the gas injection surface is viewed from above, and the area of ​​the injection ports per unit area of ​​the second region being a ratio of a sum of cross-sectional areas of the second injection ports to an area of ​​the second region when the gas injection surface is viewed from above.

[0005] A second aspect of the present invention is a holding member used in a glass manufacturing apparatus that produces glass by cooling heated and melted glass raw material suspended by a gas, the holding member having a gas injection surface with a plurality of injection ports for injecting the gas, the gas injection surface having a first region having first injection ports that are some of the plurality of injection ports, and a second region having second injection ports different from the first injection ports among the plurality of injection ports, the first region being located inside the second region in a top view of the gas injection surface, the number of the injection ports per unit area in the first region being smaller than the number of the injection ports per unit area in the second region, and the number of the injection ports per unit area in the first region being a ratio of the number of the first injection ports to the area of ​​the first region when the gas injection surface is viewed from above, The number of the injection ports per unit area of ​​the second region is the ratio of the number of the second injection ports to the area of ​​the second region when the gas injection surface is viewed from above.

[0006] A third aspect of the present invention is a holding member used in a glass manufacturing apparatus that produces glass by cooling heated and melted glass raw materials suspended by a gas, the holding member having a gas inlet surface having an inlet for introducing the gas, and a gas injection surface having a plurality of nozzles for injecting the gas introduced from the gas inlet surface, the gas injection surface having a first region having first nozzles that are some of the plurality of nozzles, and a second region having second nozzles different from the first nozzles among the plurality of nozzles, the first region being located inside the second region when viewed from above the gas injection surface, and the gas introduction surface having a convex shape.

[0007] A fourth aspect of the present invention is a holding member used in a glass manufacturing apparatus that produces glass by cooling heated and melted glass raw materials suspended by a gas, the holding member having a gas inlet surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas inlet surface and a second region having injection ports for injecting the gas, the first region being located inside the second region in a top view of the gas injection surface, the holding member having a first portion enclosed by a plane including a line extending from the first region perpendicularly to the gas inlet surface, and a second portion enclosed by a plane including a line extending from the second region perpendicularly to the gas inlet surface, the thickness of the first portion being the length of a line extending from a point in the first region relative to the gas inlet surface in the direction of gravity, the thickness of the first portion being thicker than the thickness of the second portion being the length of a line extending from a point in the second region relative to the gas inlet surface in the direction of gravity.

[0008] A fifth aspect of the present invention is a holding member used in a glass manufacturing apparatus that produces glass by cooling heated and melted glass raw material suspended by a gas, the holding member having a gas inlet surface having an inlet for introducing the gas, and a gas injection surface including a first region having a plurality of injection ports for injecting the gas introduced from the gas inlet surface and a second region having injection ports for injecting the gas, the first region being located inside the second region in a top view of the gas injection surface, and an average thickness (K1) of the holding member between the first region and the gas inlet surface being greater than an average thickness (K2) of the holding member between the second region and the gas inlet surface.

[0009] A sixth aspect of the present invention is a glass manufacturing apparatus including the holding member described above.

[0010] A seventh aspect of the present invention is a method for producing glass, comprising: a levitating step of blowing gas onto the glass frit from the nozzle of the holding member described above to levitate the glass sample; a melting step of melting the glass frit by irradiating the levitated sample with laser light; and a cooling step of cooling the molten glass frit. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a glass manufacturing apparatus equipped with a levitation furnace including a holding member according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram (cross-sectional view) showing a state in which the sample suspended above the holding member in FIG. 1 is heated. [Figure 3] 2 is a schematic diagram (cross-sectional view) of a holding member according to the present embodiment. FIG. [Figure 4] FIG. 1 is a partial schematic diagram (top view) (part 1) of a concave surface 1020 of a holding member 102 according to the present embodiment. [Figure 5] 1 is a schematic diagram (cross-sectional view) illustrating the shape of a concave surface 1020 of a holding member 102 according to the present embodiment. [Figure 6] FIG. 1 is a schematic diagram (top view) (part 1) for explaining the relationship between the concave surface and the injection port according to the present embodiment. [Figure 7] FIG. 10 is a schematic diagram (top view) (part 2) for explaining the relationship between the concave surface and the injection port according to the present embodiment. [Figure 8] FIG. 10 is a schematic diagram (top view) (part 3) for explaining the relationship between the concave surface and the injection port according to the present embodiment. [Figure 9] FIG. 10 is a partial schematic diagram (top view) (part 2) of the concave surface of the holding member according to the present embodiment. [Figure 10] FIG. 10 is a schematic diagram (cross-sectional view) (part 1) of a holding member according to a second embodiment. [Figure 11] FIG. 10 is a schematic diagram (cross-sectional view) (part 2) of the holding member according to the second embodiment. [Figure 12] FIG. 10 is a schematic diagram (cross-sectional view) (part 3) of the holding member according to the second embodiment. [Figure 13] FIG. 10 is a schematic diagram (cross-sectional view) (part 4) of the holding member according to the second embodiment. [Figure 14] 10A and 10B are schematic diagrams (top view and cross-sectional view) (part 1) of a holding member according to a third embodiment. [Figure 15] 10A and 10B are schematic diagrams (top view and cross-sectional view) (part 2) of a holding member according to the third embodiment. [Figure 16] 10A and 10B are schematic diagrams (top view and cross-sectional view) (part 3) of a holding member 123 according to the third embodiment. [Figure 17] 10A and 10B are schematic diagrams (top view and cross-sectional view) (part 4) of a holding member 124 according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described. The present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content.

[0013] In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0014] Furthermore, terms with "abbreviation" attached indicate the meaning of the term excluding "abbreviation" within the scope of common general technical knowledge of a person skilled in the art, and also include the meaning itself excluding "abbreviation." The same is true vice versa. For example, the term "circle" does not have "abbreviation" attached, but naturally includes the meaning of "approximately circle" as long as it does not contradict the gist of the invention.

[0015] Furthermore, "top view" or "top view" refers to the surface seen from the direction of the top surface of the holding member 102 when the holding member 102 described below is placed with the concave surface 1020 of the holding member 102 facing up on a horizontal surface perpendicular to the direction of gravity.

[0016] Furthermore, "cross-sectional view" or "cross-sectional view" refers to a cross section passing through the center or center of gravity of the concave surface 1020 when the holding member 102 is placed with the concave surface 1020 facing up on a horizontal surface perpendicular to the direction of gravity.

[0017] <Holding member 102 and levitation furnace of the first embodiment>

[0018] FIG. 1 is a schematic diagram of a glass manufacturing apparatus 1 equipped with a levitation furnace including a holding member 102 according to this embodiment, FIG. 2 is a schematic diagram (cross-sectional view) showing the state in which a sample M levitated on the holding member 102 in FIG. 1 is being heated, and FIG. 3 is a schematic diagram (cross-sectional view) of the holding member 102 according to this embodiment.

[0019] As shown in Fig. 1, glass manufacturing apparatus 1 is an optical glass manufacturing apparatus equipped with a gas jet levitation furnace. Glass manufacturing apparatus 1 produces glass by heating and melting glass raw materials while levitating the glass raw materials using gas. Glass manufacturing apparatus 1 includes a levitation furnace including a holding member 102 that blows gas onto sample M containing glass raw materials to levitate it, a laser light source 103 that irradiates the levitated sample M with laser light L, a radiation thermometer 106 that measures the temperature of the levitated sample M, a computer 107 that controls the output of laser light source 103 based on temperature information from radiation thermometer 106, and a gas flow regulator 110 that adjusts the flow rate of gas supplied to holding member 102.

[0020] In the glass manufacturing apparatus 1, the sample M floating above a holding member 102 arranged on a stage 101 is heated in a non-contact manner by irradiation with laser light L. As a result, the sample M melts and becomes a molten liquid having a substantially spherical or ellipsoidal shape due to its own surface tension, and floats in this state. The sample M then solidifies as it cools, becoming optical glass.

[0021] Non-contact heating of the sample M is performed by irradiating the sample M with laser light L emitted from a laser light source 103 via mirrors 104 and 105. The temperature of the sample M heated by irradiation with the laser light L is monitored by a radiation thermometer 106. Based on the temperature information of the sample M monitored by the radiation thermometer 106, the output of the laser light source 103 is controlled by a computer 107. In addition, the state of the sample M is imaged by a CCD camera 108, and the image is output to a monitor 109. The laser light source 103 is not particularly limited, and examples thereof include a carbon dioxide laser, a semiconductor laser, a fiber laser, and a YAG laser.

[0022] The flow rate of the gas fed into the holding member 102 is controlled by a gas flow regulator 110. The type of gas is not particularly limited, and any known gas can be used as appropriate. Specific examples include oxygen, carbon dioxide, nitrogen, argon, and air. The shape of the nozzle (not shown) connected to the holding member 102 is not particularly limited, and any known method can be used as appropriate.

[0023] After the stably levitated sample M is heated in a non-contact manner, the laser light L is shut off, whereby the melt (sample M) is cooled and solidified, yielding optical glass.

[0024] 2, the holding member 102 has a first surface S1 having a concave surface (gas injection surface) 1020 facing the sample M, and a second surface S2 which is a gas introduction surface located on the opposite side of the first surface S1. The second surface S2 has an inlet 1022 through which gas is introduced, and the concave surface 1020 of the first surface S1 has an injection port 1024 for injecting gas. The inlet 1022 supplies the gas to the injection port 1024 on the concave surface 1020.

[0025] 3, the nozzle 1024 is composed of nozzle 1024a provided in the center of the first surface S1 and nozzles 1024b, c, and d provided in the peripheral portion. The number, shape, and arrangement of the nozzles 1024 are not particularly limited, and suitable conditions can be selected as appropriate. By spraying gas onto the sample M from the nozzles 1024, the sample M can be stably suspended above the holding member 102.

[0026] Furthermore, the holding member 102 preferably includes a through hole 1026 that communicates the inlet 1022 and the ejection port 1024. The through hole 1026 allows the gas supplied from the inlet 1022 provided in the second surface S2 to be efficiently sent toward the ejection port 1024 provided in the concave surface 1020 of the first surface S1. As an example, the cross section of the through hole 1026 parallel to the direction of gravity is rectangular.

[0027] In addition, the inlet 1022 can be said to be an inlet for introducing gas, and the outlet 1024 can be said to be an outlet for injecting gas. In this embodiment, for example, the multiple outlets 1024 of the concave surface 1020 each communicate with one inlet 1022.

[0028] In Figure 3, there are formed through holes 1026a connecting inlet 1022a and outlet 1024a, through hole 1026b connecting inlet 1022b and outlet 1024b, through hole 1026c connecting inlet 1022c and outlet 1024c, and through hole 1026d connecting inlet 1022d and outlet 1024d.

[0029] In this embodiment, not all of the inlets 1022 and all of the injection ports 1024 may be connected by the through-holes 1026 , and only some of them may be connected by the through-holes 1026 .

[0030] Next, the arrangement of the injection ports 1024 of the holding member 102 will be further described.

[0031] <Concave surface 1020 overview example 1>

[0032] FIG. 4 is a partial schematic diagram (top view) of the concave surface 1020 of the holding member 102 according to this embodiment.

[0033] 4, the concave surface 1020 is circular in top view, with a center point O as its center and a radius R. A circle with a radius R1 from the center point O of the circle is a first circle C1, and a circle with a radius R2 is a second circle C2. Note that the "center point" specifically means the center of the circle when the shape of the concave surface 1020 of the first surface S1 when viewed from above is circular, and means the center of gravity when the shape when viewed from above is an ellipse or a polygon such as a rectangle.

[0034] That is, the concave surface 1020 has, in a top view, a region of a first circle C1 and a region of a second circle C2 having a radius R2 that is greater than or equal to the radius R1 of the first circle C1, and they are concentric and adjacent. The concave surface 1020 has a first region P1 that is the region of the first circle C1 and a second region P2 that is an annular region obtained by excluding the region of the first circle C1 from the region of the second circle C2. The first region P1 is a region that includes the center or the centroid in the top view of the concave surface 1020. In other words, the first region P1 is located closer to the inside (closer to the center or the centroid) of the concave surface 1020 than the second region P2. Note that the radius R2 of the second circle C2 may be equal to the radius R of the concave surface 1020. That is, the concave surface 1020 may be composed of the first region P1 and the second region P2.

[0035] The first region P1 is at least a part of a substantially circular region having a radius of r or less from the center point O in the top view of the concave surface 1020. Note that r < R. Also, the second region P2 is at least a part of a substantially annular region having an inner peripheral radius of r or more in the top view of the concave surface 1020.

[0036] In the top view, the first region P1 is preferably a substantially circular region having a radius of 0.2R (0.2 times the radius R) or less from the center point O with respect to the radius R of the concave surface 1020, and more preferably 0.1R or less. Also, the radius R1 is preferably 1 to 3 mm. The lower limit value of the radius R1 is more preferably 1.5 mm, and the upper limit value is more preferably 2.5 mm.

[0037] In the top view, with respect to the radius R of the concave surface 1020, the radius R2 corresponding to the outer peripheral radius of the annular region in the second region P2 may be equal to the radius R, and more preferably 0.9R (0.9 times the radius R) or less, and even more preferably 0.8R or less. Also, the radius R2 is preferably 3 to 8 mm. The lower limit value of the radius R2 is more preferably 4 mm, and the upper limit value is more preferably 7 mm.

[0038] The second region P2 may or may not be adjacent to the first region P1 as long as it is outside the first region P1. The case where the second region P2 is not adjacent will be described later.

[0039] When the concave surface 1020 is circular in top view, the radius R of the concave surface 1020 is preferably 5 to 10 mm. The lower limit of the radius R of the concave surface 1020 is more preferably 5.5 mm, and even more preferably 6.5 mm. The upper limit of the radius R of the concave surface 1020 is more preferably 9.5 mm, and even more preferably 8.5 mm. When the radius R of the concave surface 1020 is within the above range, the sample M can be more stably suspended, and as a result, a larger glass gob or optical glass can be produced. Here, a glass gob refers to a block of glass formed directly from a glass melt.

[0040] In this embodiment, the concave surface 1020 of the first surface S1 has a circular shape when viewed from above, but this is not limiting. For example, the concave surface 1020 of the first surface S1 may have an elliptical shape when viewed from above, or may have a polygonal shape such as a rectangular shape. When the shape is not a perfect circle, the "radius" refers to the shortest diameter from the center of gravity.

[0041] FIG. 5 is a schematic diagram (cross-sectional view) illustrating the shape of the concave surface 1020 of the holding member 102 according to this embodiment.

[0042] In a cross-sectional view of the concave surface 1020, the maximum depth H of the concave surface 1020 is preferably 4 to 10 mm. The maximum depth H of the concave surface 1020 here refers to the distance from the opening of the concave surface 1020 to the deepest point of the concave surface 1020. The lower limit of the maximum depth H of the concave surface 1020 is more preferably 5 mm, and even more preferably 5.5 mm. The upper limit of the maximum depth H of the concave surface 1020 is more preferably 6.5 mm, and even more preferably 6 mm. When the maximum depth H of the concave surface 1020 is within the above range, the sample M can be more stably suspended, and as a result, a larger glass gob can be produced.

[0043] Furthermore, the cross-sectional shape of the concave surface 1020 is not particularly limited, but from the viewpoint of suspending the sample M more stably, it is preferably semicircular or semielliptical.

[0044] The holding member 102 is formed of a non-porous material such as metal. While the material of the holding member 102 is not particularly limited, it is preferable that at least a part or all of the member contains at least one material selected from the group consisting of stainless steel (SUS), silicon carbide (SiC), alumina (Al2O3), zirconia (ZrO2), duralumin, copper (Cu), and carbon (C). These materials have excellent thermal shock resistance and abrasion resistance even at high temperatures, so that gas can be sprayed onto the sample M with higher precision, even at the high temperatures at which laser beam heating is performed, and the sample M can be stably levitated.

[0045] <Configuration example 1 of injection nozzle 1024>

[0046] 6 is a schematic diagram (top view) (part 1) illustrating the relationship between the concave surface 1020 and the jet orifice 1024 according to this embodiment. The jet orifice 1024 provided in the first region P1 will be referred to as jet orifice 1024x (first jet orifice), and the jet orifice 1024 provided in the second region P2 will be referred to as jet orifice 1024y (second jet orifice) different from 1024x. The area of ​​jet orifice 1024x per unit area of ​​the first region P1 is represented by W1, and the area of ​​jet orifice 1024y per unit area of ​​the second region P2 is represented by W2. The area of ​​jet orifice 1024 refers to the area of ​​the space portion as an opening surrounded by the members of the concave surface 1020 having the jet orifice 1024.

[0047] The area W1 of the injection ports 1024x per unit area of ​​the first region P1 is calculated as follows. The area of ​​the first region P1 refers to the area of ​​the first region P1 when the concave surface 1020 is viewed from above, as shown in FIG. 4. The area of ​​the injection ports 1024x included in the first region P1 refers to the sum of the cross-sectional areas of the injection ports 1024x included in the first region P1 in a cross section of the holding member 102 in a plane perpendicular to the direction of gravity (plane AA' in FIG. 3). For example, in the case of FIG. 3, It is the sum of the cross-sectional areas of the three injection ports 1024a and 1024b. Therefore, W1 is expressed by the following formula (1). Area W1 of the injection ports 1024x per unit area of ​​the first region P1 = Sum of cross-sectional areas of the injection ports 1024x included in the first region P1 / Area of ​​the first region P1 when viewed from above (1)

[0048] The area W2 of the ejection port 1024y per unit area of ​​the second region P2 is calculated in the same manner as W1. The area of ​​the second region P2 refers to the area of ​​the second region P2 when the concave surface 1020 is viewed from above as shown in FIG. 4. The area of ​​the ejection port 1024y included in the second region P2 refers to the sum of the cross-sectional areas of the ejection ports 1024y included in the second region P2 in a cross section of the holding member 102 in a plane perpendicular to the direction of gravity (plane AA' in FIG. 3). For example, in the case of FIG. 3, it is the sum of the cross-sectional areas of the four ejection ports 1024, ejection ports 1024c and d. Therefore, W2 is expressed by the following formula (2). Area W2 of the injection port 1024y per unit area of ​​the second region P2 = Sum of areas of the injection ports 1024y included in the second region P2 / Area of ​​the second region P2 when viewed from above (2)

[0049] Furthermore, the AA' cross section is preferably a cross section at the lowest position when the concave surface 1020 is viewed from the side.

[0050] The areas of the injection ports 1024x and 1024y may also be as follows: The areas of the injection ports 1024x and 1024y may be the areas of the injection ports 1024x and 1024y when the concave surface is viewed from above.

[0051] In the example shown in Figure 6, the area W1 of the ejection port 1024x per unit area of ​​the first region P1 is smaller than the area W2 of the ejection port 1024y per unit area of ​​the second region P2. W1 <W2 ···(3) is.

[0052] The ratio (W1 / W2) of the area W1 of the injection ports 1024x per unit area of ​​the first region P1 to the area W2 of the injection ports 1024y per unit area of ​​the second region P2 is preferably 0.05 to 0.7, with the lower limit of W1 / W2 being more preferably 0.1 and the upper limit being more preferably 0.4.

[0053] In this example, by configuring the nozzle 1024 of the concave surface 1020 as described above, the gas flow rate per unit time from the nozzle 1024y provided in the second region P2 is greater than the gas flow rate per unit time from the nozzle 1024x provided in the first region P1. This allows the sample M to be stably levitated near the irradiation target position of the laser light L (stable levitation).

[0054] In the past, for example, in the case of a method for producing optical glass using a container such as a crucible (sometimes called the container method), it was necessary to increase the glass-forming ability by adding a large amount of network-forming oxides such as SiO2, B2O3, P2O5, GeO2, etc. Therefore, when a glass composition containing a large amount of a material that is not a network-forming oxide and a small amount of the above-mentioned network-forming oxides is used, crystallization (heterogeneous nucleation) occurs starting from the container-melt interface, making vitrification difficult.

[0055] Furthermore, with the holding member used in the conventional levitation furnace method, gas is blown from below the sample, but it is difficult to keep the sample stably levitated above the holding member (stable levitation), which makes it difficult to precisely irradiate and heat the sample with laser light, and results in the inability to produce large glass gobs.

[0056] Regarding such problems, by using the holding member 102 according to this embodiment, the conditions for blowing gas onto the sample M can be controlled with high precision. As a result, a stable levitation state can be maintained to a degree that was not possible with conventional methods (high levitation stability), and a larger glass gob can be produced. In other words, high stability of levitation contributes to precise irradiation heating with a laser beam, larger size of the obtained optical glass (glass gob), uniformity of the component composition, etc.

[0057] Glass gobs are sometimes used as materials for optical lenses in various optical devices, such as microscope objective lenses and camera lenses, and there is a demand for the stable production of large glass gobs. The use of the holding member according to this embodiment can meet this demand.

[0058] Furthermore, the number of ejection ports 1024x per unit area in the first region P1 is defined as T1, and the number of ejection ports 1024y per unit area in the second region P2 is defined as T2.

[0059] The multiple jet ports 1024 of the concave surface 1020 shown in Fig. 6 are arranged at approximately equal intervals. That is, the distance L1 from the center of each jet port 1024 to the center of another jet port 1024 adjacent to that jet port 1024 is approximately equal. In other words, in the example shown in Fig. 6, the number T1 of jet ports 1024x per unit area in the first region P1 is equal to the number T2 of jet ports 1024y per unit area in the second region P2.

[0060] To stably levitate the sample M, the radius of the injection port 1024x is preferably 0.05 mm to 0.2 mm. The lower limit of the radius of 1024x is more preferably 0.1 mm, and the upper limit is more preferably 0.15 mm. The radius of the injection port 1024y is preferably 0.2 mm to 0.5 mm. The lower limit of the radius of 1024y is more preferably 0.3 mm, and 0.4 mm is more preferably.

[0061] Note that the number of the ejection ports 1024 in this example is not limited to this. It is sufficient that the area W1 of the ejection ports 1024x per unit area of ​​the first region P1 is smaller than the area W2 of the ejection ports 1024y per unit area of ​​the second region P2, and for example, the number T1 of the ejection ports 1024x per unit area of ​​the first region P1 may be greater than the number T2 of the ejection ports 1024 per unit area of ​​the second region P2.

[0062] Furthermore, one jet port 1024x larger than one jet port 1024y in the second region P2 may be present in the first region P1. Similarly, one jet port 1024y smaller than one jet port 1024x in the first region P1 may be present in the second region P2.

[0063] <Configuration example 2 of injection nozzle 1024>

[0064] 7 is a schematic diagram (top view) (part 2) for explaining the relationship between the concave surface 1020 and the injection ports 1024 according to this embodiment. In the example shown in FIG. 7, the number T1 of the injection ports 1024x per unit area of ​​the first region P1 is smaller than the number T2 of the injection ports 1024y per unit area of ​​the second region P2. That is, T1 <T2 ···(4) is.

[0065] Furthermore, the ratio (T1 / T2) of the number T1 of the injection ports 1024x per unit area in the first region P1 to the number T2 of the injection ports 1024y per unit area in the second region P2 is preferably 0.05 to 0.5. The lower limit of T1 / T2 is more preferably 0.1, and the upper limit is more preferably 0.3.

[0066] For example, in a cross-sectional view of the holding member 102, the through holes can be arranged so that they are spaced apart sparsely in a first region P1 including the center point O of the concave surface 1020, and the through holes can be arranged so that they become more densely spaced as they approach the end of the concave surface 1020. By configuring in this way, the relationship expressed by equation (4) can be satisfied.

[0067] In this example, the number of injection ports 1024 that satisfies formula (4) is provided in the concave surface 1020, and the injection ports 1024 are formed so that the area W1 of the injection ports 1024x per unit area in the first region P1 is smaller than the area W2 of the injection ports 1024y per unit area in the second region P2. That is, in this example, as in the example shown in Fig. 6, the gas flow rate per unit time from the injection ports 1024 provided in the second region P2 is greater than the gas flow rate per unit time from the injection ports 1024 provided in the first region P1. Therefore, the sample M can be stably suspended near the irradiation target position of the laser light L.

[0068] When the sample M is brought into a molten state by laser heating, its viscosity and surface tension decrease with increasing temperature, making it more susceptible to deformation and vibration when subjected to gas pressure. Furthermore, as the volume and total weight of the sample M increase, it becomes more susceptible to the effects of its own weight and gas flow, resulting in more pronounced deformation and vibration of the melt. Therefore, it has been difficult to stably levitate a large sample M. However, with the configuration of this embodiment, the gas flow rate per unit time in the second region is greater than the gas flow rate per unit time in the first region, making it possible to stably levitate even a large sample M.

[0069] 7, the area of ​​each of the ejection ports 1024x in the first region P1 is equal to the area of ​​each of the ejection ports 1024y in the second region P2. However, the area of ​​each of the ejection ports 1024 in this example is not limited to this. <Configuration example 3 of injection nozzle 1024>

[0070] Fig. 8 is a schematic diagram (top view) (part 3) illustrating the relationship between the concave surface 1020 and the ejection ports 1024 according to this embodiment. In the example shown in Fig. 8, the area W1 of the ejection ports 1024x per unit area of ​​the first region P1 is smaller than the area W2 of the ejection ports 1024y per unit area of ​​the second region P2. Furthermore, in the example shown in Fig. 8, the number T1 of the ejection ports 1024x per unit area of ​​the first region P1 is smaller than the number T2 of the ejection ports 1024y per unit area of ​​the second region P2.

[0071] That is, in the example shown in FIG. 8, the above-mentioned formulas (3) and (4) are satisfied.

[0072] In this example, as in the other examples described above, the gas flow rate per unit time from the injection port 1024 provided in the second region P2 is greater than the gas flow rate per unit time from the injection port 1024 provided in the first region P1. That is, the sample M can be stably suspended near the irradiation target position of the laser light L.

[0073] 6 to 8. In order to stably levitate the sample M, it is preferable that the arrangement of the ejection ports 1024 in the top view of the concave surface 1020 has symmetry, such as point symmetry or line symmetry, about the center point O (or center of gravity) of the concave surface 1020 in each of the first region P1 or the second region P2.

[0074] <Concave surface 1020 overview example 2>

[0075] 9 is a partial schematic diagram (top view) (part 2) of the concave surface 1020 of the holding member 102 according to this embodiment. In the partial schematic diagram shown in FIG. 4, the first region P1 and the second region P2 are adjacent to each other. In the example shown in this figure, the first region P1 and the second region P2 are not adjacent to each other.

[0076] When viewed from above, the concave surface 1020 has a first circle C1 region, a second circle C2 region having a radius R2 greater than or equal to the radius R1 of the first circle C1, and a third circle C3 region having a radius R3 greater than the radius R2 of the second circle C2, all arranged concentrically. The first region P1 is the region of the first circle C1, and the second region P2 is an annular region obtained by excluding the region of the second circle C2 from the region of the third circle C3.

[0077] In this example, the first region P1 preferably has a radius R1 of 3 mm or less from the center point O when viewed from above the concave surface 1020. The radius R1 is preferably 1 to 3 mm, with the lower limit being more preferably 1.5 mm and the upper limit being more preferably 2.5 mm.

[0078] In the second region P2, when viewed from above on the concave surface 1020, the radius R2, which corresponds to the inner radius of the annular region, is preferably 3 to 5 mm. The lower limit of the radius R2 is more preferably 3.5 mm, and the upper limit of the radius R2 is more preferably 4.5 mm. The radius R3, which corresponds to the outer radius of the annular region, is preferably 5 to 9 mm. The lower limit of the radius R3 is more preferably 5.5 mm, and the upper limit of the radius R3 is even more preferably 8 mm. Furthermore, the radius R2 is preferably 1 to 3 times the radius R1, and the radius R3 is preferably 3.5 to 6 times the radius R1.

[0079] The concave surface 1020 has a circular shape with a radius R when viewed from above.

[0080] When viewed from above the concave surface 1020, the first region P1 is preferably a circular region in which the radius R1 from the center point O is 0.2R (0.2 times the radius R) or less, where R is the radius of the concave surface 1020.

[0081] In the second region P2, when viewed from above on the concave surface 1020, the radius R2 from the center point O is preferably 0.4R (0.4 times the radius R) or more, and more preferably 0.5R (0.5 times the radius R) or more, where R is the radius of the concave surface 1020. Furthermore, the radius R3 from the center point O is preferably 0.9R (0.9 times the radius R) or less, and more preferably 0.8R (0.8 times the radius R) or less.

[0082] As shown in this example, even when the first region P1 and the second region P2 are not adjacent to each other, the concave surface 1020 can be configured so that the gas flow rate per unit time from the nozzle 1024 provided in the second region P2 is greater than the gas flow rate per unit time from the nozzle 1024 provided in the first region P1. This makes it possible to maintain high floating stability.

[0083] Up to this point, we have described as an example a holding member 102 in which through holes for passing gas extend vertically inside the member, but the holding member according to this embodiment is not limited to this form and may have other forms.

[0084] <Configuration Example 1 of the Holding Member (Holding Member 111) of the Second Embodiment>

[0085] 10 is a schematic diagram (cross-sectional view) (part 1) of a holding member 111 in the second embodiment. Differences from the first embodiment will be described below. At least a portion of the holding member 111 in the second embodiment is porous.

[0086] By including a porous material, the gas supplied to the inlet 1112 can be sprayed onto the sample M from the injection port 1114 via the internal pore structure. In this way, the above-mentioned through-holes may be holes in a porous material. That is, the holes in the porous body of the holding member 111 can be considered one form of the above-mentioned through-holes. FIG. 10 illustrates a case where all of the members constituting the holding member 111 are porous. Specific examples of porous materials include stainless steel (SUS), silicon carbide (SiC), alumina (Al2O3), zirconia (ZrO2), and carbon (C).

[0087] If the pore diameter of the porous body constituting the holding member 111 is too small, the pressure loss increases and the gas cannot pass through sufficiently. On the other hand, if the pore diameter is too large, the surface shape including the concave surface 1110 becomes rough. Therefore, the pore diameter of the porous body constituting the holding member 111 is preferably 1 to 100 μm. The lower limit of the pore diameter is more preferably 5 μm, and even more preferably 9 μm. The upper limit of the pore diameter is more preferably 50 μm, and even more preferably 20 μm.

[0088] When the pore diameter of the porous body constituting the holding member 111 is within the above range, not only can the gas pass through appropriately, but also the influence on the surface shape of the concave surface 1110 can be suppressed.

[0089] By varying the density of the internal pore structure of the holding member 111, the gas can be sprayed so as to satisfy the relationship expressed by formula (3) or formula (4). Here, the portion of the holding member 111 having pores that supply gas to the nozzles 1114 in the first region P1 is defined as part Q1, and the portion of the holding member 111 having pores that supply gas to the nozzles 1114 in the second region P2 is defined as part Q2. For example, the porosity of the portion Q1 of the holding member 111 corresponding to the first region P1, which includes the center point O of the concave surface 1110 of the first surface S1, is defined as V1, and the porosity of the portion Q2 of the holding member 111 corresponding to the second region P2 located outside the first region P1 is defined as V2. Note that the porosity here refers to the ratio of the volume of open space to the total volume of a substance.

[0090] In this embodiment, the porosity V1 of the portion Q1 of the holding member 111 corresponding to the first region P1 including the center point O of the concave surface 1110 of the first surface S1 is lower than the porosity V2 of the portion Q2 of the holding member 111 corresponding to the second region P2 located outside the first region P1. V1 <V2 ···(5) is.

[0091] By configuring the porosity V1 of the portion Q1 to be lower than the porosity V2 of the portion Q2, the area W1 of the nozzles 1114 per unit area in the first region P1 is smaller than the area W2 of the nozzles 1114 per unit area in the second region P2. That is, the above-mentioned formula (3) is satisfied, and the gas flow rate per unit time from the nozzles 1024y provided in the second region P2 is greater than the gas flow rate per unit time from the nozzles 1024x provided in the first region P1. This allows the sample M to be stably levitated near the target position for irradiation with the laser light L (stable levitation). Note that the number T1 of the nozzles 1114 per unit area in the first region P1 can be smaller than the number T2 of the nozzles 1114 per unit area in the second region P2.

[0092] As a result of forming the holding member 111 from a porous material, at least one of the multiple jet ports 1114 of the concave surface 1110 communicates with the multiple inlets 1112. The portion Q1 of the holding member 111 corresponds to the multiple jet ports 1114 provided in the first region P1, and includes pores and inlets 1112 that communicate with the jet ports 1114. Similarly, the portion Q2 of the holding member 111 corresponds to the multiple jet ports 1114 provided in the second region P2, and includes pores and inlets 1112 that communicate with the jet ports 1114.

[0093] In this embodiment, the inlet 1112 is not limited to being provided on the second surface S2. For example, the gas may be introduced from a side surface of the holding member 111. In other words, the gas introduction surface having the inlet 1112 may be at least one of the side surface S3 of the holding member 111 and the second surface S2 opposite the concave surface 1110.

[0094] In addition, the holding member 111 in this embodiment can be formed by combining a porous body located in the portion Q1 and a porous body located in a portion Q2 different from the portion Q1. As another example, the holding member 111 can be made of a single porous body, and the porous body can be formed so that the porosity of the portion Q1 and the portion Q2 is different.

[0095] According to the holding member 111 of this embodiment, the gas flow rate per unit time from the injection port 1114 provided in the second region P2 is greater than the gas flow rate per unit time from the injection port 1114 provided in the first region P1. This allows the sample M to be stably levitated near the irradiation target position of the laser light L (stable levitation).

[0096] <Configuration Example 2 of the Holding Member (Holding Member 112) of the Second Embodiment>

[0097] 11 is a schematic diagram (cross-sectional view) (part 2) of the holding member 112 in the second embodiment. The holding member 112 shown in this figure includes a member made of a porous material and a member made of a non-porous material.

[0098] The holding member 112 has an inlet 1122 and an injection port 1124, and is composed of a non-porous portion 1126 and a porous portion 1128, with a through-hole disposed between the non-porous portion 1126 and the porous portion 1128. That is, the concave surface 1120 of the first surface S1 has both a porous region and a non-porous region, which allows for control of the gas flow rate. The non-porous portion 1126 is made of a non-porous material, such as stainless steel (SUS), silicon carbide (SiC), alumina, zirconia (ZrO2), duralumin, copper (Cu), carbon (C), or any other metal.

[0099] The non-porous portion 1126 corresponds to a first region P1 including the center of the concave surface 1120, and the porous portion 1128 corresponds to a second region P2 located outside the first region P1. The through-holes between the non-porous portion 1126 and the porous portion 1128 are considered to be located in the second region P2. In the holding member 112, the gas flow rate per unit time from the injection ports 1124 provided in the second region P2 is greater than the gas flow rate per unit time from the injection ports 1124 provided in the first region P1.

[0100] In this configuration example, the inlet 1122 is not limited to being provided on the second surface S2, and the gas may be introduced from the side surface S3 of the holding member 112.

[0101] <Configuration Example 3 of Holding Member (Holding Member 113) of Second Embodiment>

[0102] 12 is a third schematic diagram (cross-sectional view) of the holding member 113 according to the second embodiment. In the holding member 113 shown in this figure, at least some of the nozzles 1134 in the second region P2 inject gas in a substantially horizontal direction that is substantially perpendicular to the direction of gravity.

[0103] Holding member 113 has member 1136 and member 1138. The material of member 1136 is not particularly limited. Member 1136 may be formed of a porous material having injection port 1134, or may be formed of a non-porous material having injection port 1134, or may be formed of a non-porous material without injection port 1134. Member 1136 is provided at a position corresponding to first region P1 including center point O of concave surface 1130.

[0104] Member 1138 has an ejection port 1134, and ejects gas introduced from inlet 1132 from outlet 1134. Member 1138 ejects gas in a substantially horizontal direction. Member 1138 is provided at a position corresponding to second region P2 outside first region P1. Note that inlet 1132 that introduces gas into ejection port 1134 may be located on a side surface of holding member 113, or may be located at the bottom of holding member 113 and introduce gas into ejection port 1134 via a curved, hollow member.

[0105] In the holding member 113, the gas flow rate per unit time in the second region P2 is greater than the gas flow rate per unit time in the first region P1.

[0106] With this configuration, the gas is blown onto the sample M from a substantially horizontal direction, and the sample M can be levitated more stably.

[0107] <Configuration Example 4 of the Holding Member (Holding Member 114) of the Second Embodiment>

[0108] 13 is a schematic diagram (part 4) of the holding member 114 in the second embodiment. The holding member 114 shown in this drawing has a member 1141 and a member 1149.

[0109] The member 1141 has a concave surface 1140, and has a first region P1 and a second region P2 on the concave surface 1140. The member 1141 may be any of the above-described holding members 102, 111, and 112. In the member 1141, the area W1 of the ejection port 1134 per unit area of ​​the first region P1 and the area W2 of the ejection port 1134 per unit area of ​​the second region P2 satisfy the above-described formula (3).

[0110] The member 1149 is a member located above the concave surface 1140, and has an outlet 1149a that injects gas in a substantially horizontal direction that is substantially perpendicular to the direction of gravity. By having the outlet 1149a that injects gas in a substantially horizontal direction in addition to the member 1141, the sample M can be levitated more stably.

[0111] Although not shown, the process of levitating the sample by spraying gas onto it in a gas levitation furnace and melting the sample by irradiating it with laser light is preferably carried out in a chamber that can be depressurized. By spraying gas onto the sample under reduced pressure, the gas can more easily pass through the porous or through-holes in the holding member. As a result, even with a low gas flow rate, high levitation stability can be achieved and turbulence can be suppressed. Alternatively, the gas may be heated, which can also suppress turbulence. Furthermore, the irradiated laser light L may be defocused or scanned. This allows the sample to be heated uniformly and improves levitation stability.

[0112] <Configuration Example 1 of the Holding Member (Holding Member 121) of the Third Embodiment>

[0113] 14 is a schematic diagram (top view and cross-sectional view) (part 1) of a holding member 121 in the third embodiment. The upper part of FIG. 14 is a top view of the holding member 121, and the lower part of FIG. 14 is a cross-sectional view of the holding member 121. Below, differences from the first and second embodiments will be described.

[0114] The holding member 121 in the third embodiment has a convex second surface S2, which is a gas inlet surface. The second surface S2 has a portion J1 enclosed by a plane including a line extending from the first circle C1 to the second surface S2 (or the side surface S3) in the direction of gravity (perpendicular to the first circle C1) and a portion J2 enclosed by a plane including a line extending from the second circle C2 to the second surface S2 (or the side surface S3) in the direction of gravity. The thickness of the portion J1, which is the length of the line extending from a point within the first circle C1 to the second surface S2 (or the side surface S3) in the direction of gravity, is thicker than the thickness of the portion J2, which is the length of the line extending from a point within the second circle C2 to the second surface S2 (or the side surface S3) in the direction of gravity. As will be described in detail later, the portion J1 is not included in the portion J2. As an example, the second surface S2 is substantially horizontal near the center and tapered toward the periphery, tapering downward toward the center. In FIG. 14, the surface forming the tapered shape gradually tapering toward the center is referred to as the side surface S3. In other words, the second surface S2 has a generally truncated cone shape that gradually widens in the upward direction.

[0115] In this example, the holding member 121 is made of a porous material. By changing the thickness of the holding member 121, the floating stability of the sample M can be improved.

[0116] Here, the portion of the holding member 121 enclosed by a plane including a straight line extending vertically from the first circle C1 to the second surface S2 (or side surface S3) is defined as part J1, and the portion enclosed by a plane including a straight line extending vertically from the second circle C2 to the second surface S2 (or side surface S3) excluding part J1 is defined as part J2. Part J1 is the portion of the holding member 121 corresponding to a first region P1 including the center point O of the concave surface 1210 of the first surface S1, and part J2 is the portion of the holding member 121 corresponding to a second region P2 located outside the first region P1.

[0117] In this example, "vertical" refers to the vertical direction when the holding member 121 is placed on a horizontal plane perpendicular to the direction of gravity with the concave surface 1210 of the holding member 121 facing upward. For example, if the second surface S2 is a substantially flat surface, the direction is perpendicular to the second surface S2.

[0118] For example, the average thickness of portion J1 is K1, and the average thickness of portion J2 is K2. Note that the average thickness here refers to a value obtained by measuring thicknesses at a number of predetermined points in a cross-sectional view and calculating the average value of those measurements. The thickness indicates the distance from a predetermined point on concave surface 1210 to the point where a line extending perpendicularly from that point intersects with second surface S2 (or side surface S3).

[0119] In this embodiment, the average thickness K1 of the portion J1 of the holding member 121 in a cross-sectional view is greater than the average thickness K2 of the portion J2 of the holding member 121. K1>K2 (6)

[0120] In other words, in this embodiment, the average thickness K1 of the holding member 121 between the first region P1 and the second surface S2, which is the gas introduction surface, is larger than the average thickness K2 of the holding member 121 between the second region P2 and the second surface S2 (or side surface S3).

[0121] The ratio (K2 / K1) of the average thickness K2 of the portion J2 to the average thickness K1 of the portion J1 is preferably 0.5 to 0.95. The lower limit of K2 / K1 is more preferably 0.6, and the upper limit is more preferably 0.9.

[0122] In this embodiment, the thickness of the holding member 121 at the center point O in a cross-sectional view is defined as D1, and the thickness of the holding member 121 at an arbitrary point on the second region P2 is defined as D2. The shortest D2 is configured to be shorter than D1. The longest D1 is configured to be longer than D2.

[0123] This configuration creates a difference in the length of the path through which the gas passes between the portion J1 associated with the first region P1 and the portion J2 associated with the second region P2, with the path through the portion J1 being longer than the path through the portion J2. This makes the flow rate of the gas passing through the portion J2 greater than the flow rate of the gas passing through the portion J1, allowing the sample M to be stably suspended near the center point O and enabling the production of a larger glass gob.

[0124] The holding member 121 in the third embodiment can also be configured to satisfy the above formula (3) or (4), similarly to the holding members in the first and second embodiments.

[0125] <Configuration Example 2 of the Holding Member (Holding Member 122) of the Third Embodiment>

[0126] Figure 15 is a schematic diagram (top view and cross-sectional view) (part 2) of the holding member 122 in the third embodiment. The upper part of Figure 15 is a top view of the holding member 122, and the lower part of Figure 15 is a cross-sectional view of the holding member 122. The holding member 122 in this figure is made of a non-porous material.

[0127] Similar to the holding member 121, the holding member 122 has a convex second surface S2. That is, the second surface S2, including the side surface S3, has a generally truncated cone shape that gradually widens upward. Similarly to the holding member 121, the holding member 122 has an average thickness K1 in a cross-sectional view of a portion J1 of the holding member 121 that corresponds to a first region P1 including a center point O of the concave surface 1220 of the first surface S1, which is thicker than the average thickness of a portion J2 of the holding member 121 that corresponds to a second region P2 located outside the first region P1.

[0128] Also, similar to the holding member 121, if the thickness of the holding member 122 at the center point O in a cross-sectional view is D1 and the thickness of the holding member 122 at any point on the second region P2 is D2, the shortest D2 is configured to be shorter than D1.

[0129] In this configuration, the flow rate of gas passing through portion J2 is greater than the flow rate of gas passing through portion J1, so that sample M can be stably suspended near center point O, and a larger glass gob can be produced.

[0130] The holding member 122 in this example can also be configured to satisfy the above-mentioned formula (3) or formula (4), similarly to the holding members in the first and second embodiments.

[0131] <Configuration Example 3 of Holding Member (Holding Member 123) of Third Embodiment>

[0132] Fig. 16 is a schematic diagram (top view and cross-sectional view) (part 2) of the holding member 123 in the third embodiment. The upper part of Fig. 16 is a top view of the holding member 123, and the lower part of Fig. 16 is a cross-sectional view of the holding member 123. The holding member 123 in this figure is made of a porous body. Note that the holding member 123 may be made of a non-porous body, or may be made of both a porous body and a non-porous body.

[0133] Similar to the holding members 121 and 122, the holding member 123 has a convex second surface S2. More specifically, the second surface S2 of the holding member 123 has a protrusion. The area near the center of the second surface S2 is approximately horizontal. The area of ​​the second surface S2 other than the area near the center is referred to as a side surface S3.

[0134] For example, a protrusion can be formed by making the portion located directly below the first region P1 approximately horizontal and recessing the other portion. As in the above example, the portion of the holding member 123 corresponding to the first region P1 including the center point O of the concave surface 1230 of the first surface S1 is referred to as portion J1, and the portion of the holding member 123 corresponding to the second region P2 located outside the first region P1 is referred to as portion J2. The average thickness K1 of portion J1 in a cross-sectional view is greater than the average thickness of portion J2.

[0135] Also, similar to holding members 121 and 122, holding member 123 is configured such that, if the thickness of holding member 123 at center point O in a cross-sectional view is D1 and the thickness of holding member 123 at any point on second region P2 is D2, the shortest of D2 is shorter than D1.

[0136] In this configuration as well, the flow rate of gas passing through portion J2 is greater than the flow rate of gas passing through portion J1, so that sample M can be stably suspended near center point O, making it possible to produce a larger glass gob. Note that, like the holding members in the first and second embodiments, holding member 123 in this example can also be configured to satisfy the above-mentioned formula (3) or formula (4).

[0137] <Configuration Example 4 of the Holding Member (Holding Member 124) of the Third Embodiment>

[0138] FIG. 17 is a schematic diagram (top view and cross-sectional view) (part 4) of the holding member 124 in the third embodiment. The upper part of FIG. 17 is a top view of the holding member 124, and the lower part of FIG. 17 is a cross-sectional view of the holding member 124. The holding member 124 in this figure is made of a porous body. Note that the holding member 124 may be made of a non-porous body, or may be made of both a porous body and a non-porous body.

[0139] The second surface S2 of the holding member 124 has a convex shape, similar to the holding members 121, 122, and 123. More specifically, the second surface S2 of the holding member 124 is bowl-shaped, with the longest portion being the intersection of a straight line extending vertically from the center point O and the second surface S2. In other words, the second surface S2 of the holding member 124 describes a substantially parabolic curve that is convex downward in a cross-sectional view.

[0140] In the holding member 124 of this example, the average thickness K1 of the portion J1 of the holding member 124 in a cross-sectional view is also greater than the average thickness of the portion J2 of the holding member 123.

[0141] Also, similar to the holding members 121, 122, and 123, if the thickness of the holding member 124 at the center point O in a cross-sectional view is D1 and the thickness of the holding member 124 at any point on the second region P2 is D2, the shortest of D2 is configured to be shorter than D1.

[0142] In this configuration as well, the flow rate of gas passing through portion J2 is greater than the flow rate of gas passing through portion J1, so that sample M can be stably suspended near center point O, making it possible to produce a larger glass gob. Note that, like the holding members in the first and second embodiments, holding member 124 in this example can also be configured to satisfy the above-mentioned formula (3) or formula (4).

[0143] <Manufacturing method>

[0144] The method for manufacturing optical glass according to this embodiment includes the steps of blowing gas onto sample M from the gas injection portion of the holding member described above in a gas levitation furnace to levitate sample M, and irradiating laser light L onto the levitated sample M to melt the sample M, and cooling the molten sample M.

[0145] According to the method for producing optical glass of this embodiment, by using the holding member described above, there is no contact between the container and the melt (sample M), and heterogeneous nucleation can be suppressed to the greatest extent possible. Therefore, it is possible to vitrify compositions that contain little or no network-forming oxides, which cannot be produced by the container method (crucible melting). By adopting this production method, it is possible to produce optical glass of compositions that could not be vitrified in the past. Therefore, it is also possible to produce optical glass with a high refractive index and a high Abbe number.

[0146] In addition, since the gas is injected at a greater flow rate into the melt at the periphery than at the center, the melt can be stably suspended near the center point O, making it possible to produce a large glass gob. Specifically, the diameter is preferably 6 mm or more, more preferably 6.5 mm or more, and even more preferably 7 mm or more.

[0147] The optical glass obtained by the manufacturing method according to this embodiment has many advantages as described above, and therefore can be used as a high-refractive index, low-dispersion glass material or a broadband transmission material. Specific examples will be described below.

[0148] <Example>

[0149] Next, the following examples will be described, but the present invention is not limited to these examples in any way.

[0150] (Preparation of Optical Glass for Each Example) The optical glass of each example was produced using a glass manufacturing apparatus 1 equipped with a gas jet levitation furnace as shown in FIG. 1, and a holding member 121 as shown in FIG. 14. The holding member 121 in Examples 1 to 19 had a structure in which the radius (R) of the concave surface 1210 was 5.5 mm, the maximum depth (H) of the concave surface 1210 was 4.5 mm, the material was a porous stainless steel, and the pore diameter was 10 μm. The radius R1 of the first region P1 of the holding member 121 was 2.1 mm from the center point O, and the radius R2 of the outer periphery of the second region P2 was 5.5 mm from the center point O. The holding member 121 in Examples 20 to 24 had a structure in which the radius (R) of the concave surface 1210 was 8.5 mm, the maximum depth (H) of the concave surface 1210 was 6.8 mm, the material was a porous stainless steel, and the pore diameter was 10 μm. The radius R1 of the first region P1 of the holding member 121 is 5 mm from the center point O, and the radius R2 of the outer periphery of the second region P2 is 8.5 mm from the center point O.

[0151] Gas was fed at a rate of 2 to 3 L / min from the gas flow regulator 110 connected to the holding member 121. Because the holding member 121 was used, the average thickness K1 in cross section of the portion J1 of the first region P1 was greater than the average thickness K2 of the portion J2 of the second region P2.

[0152] Optical glass was then fabricated according to the following procedure. First, raw materials selected from oxides, hydroxides, carbonates, nitrates, sulfates, etc. were weighed to achieve the desired chemical composition and mixed in an alumina mortar. The raw materials were uniaxially pressed at 20 MPa to form cylindrical pellets. The resulting pellets were fired in an electric furnace at 1000–1300°C in air for 6–12 hours to produce sintered bodies. The resulting sintered bodies were roughly crushed, and 500–600 mg of each were placed in the nozzle of a holding member. The raw materials were then melted by irradiating them from above with a carbon dioxide laser while injecting oxygen gas. The molten raw materials took on a spherical or ellipsoidal shape due to their own surface tension and were suspended by the pressure of the sprayed gas. When the raw materials were completely melted, the laser output was shut off, allowing the raw materials to cool and produce roughly spherical glass gobs with diameters of 6 mm or more. In the glasses of the respective Examples, no visible volatilization was observed during melting, and no bubbles or devitrification were observed.

[0153] (Creating a glass gob) In each example, when a roughly spherical glass gob with a diameter of 6 mm or more was produced, it was described as "vitrified."

[0154] (Measurement of refractive index and Abbe number) The refractive index of glass was measured using a prism coupler (Metricon, model "2010 / M"). The glass sample was polished, and the polished surface was attached to a single crystal rutile prism. The refractive index was determined by measuring the angle of total reflection when light of the measurement wavelength was incident. Measurements were taken five times at each of three wavelengths: 473 nm, 594.1 nm, and 656 nm, and the average value was used as the measured value. Furthermore, the measured values ​​were fitted using the Drude-Voigt dispersion equation below by the least squares method to determine the refractive index at the d-line (587.562 nm), F-line (486.133 nm), and C-line (656.273 nm), as well as the Abbe number (ν d ) was calculated.

[0155]

number

[0156] (n: refractive index, m: electron mass, c: speed of light, e: elementary charge, N: number of molecules per unit volume, f: oscillator strength, λ0: characteristic resonance wavelength, λ: wavelength)

[0157] Also, the Abbe number (ν d ) is defined by the following formula:

[0158]

number

[0159] (n d : refractive index at d line, n F : Refractive index at F line, n C : refractive index at C line)

[0160] The compositions and physical properties of each example are shown in the tables. Unless otherwise specified, the content of each component is based on cation %.

[0161] [Table 1]

[0162] [Table 2]

[0163] [Table 3]

[0164] [Table 4]

[0165] From the above, it was confirmed that the manufacturing methods of each Example enable the stable production of large glass gobs, and that the obtained optical glass has a high refractive index, low dispersion, and high levels of resistance to devitrification. [Explanation of symbols]

[0166] 1...glass manufacturing apparatus, 101...stage, 102, 111, 112, 113, 114, 121, 122, 123, 124: holding member, 103...laser light source, 104, 105...mirror, 106...radiation thermometer, 107...computer, 108...CCD camera, 109...monitor, 110...gas flow regulator, 1020, 1110, 1120, 1130, 1140, 1210, 1220, 1230, 1240:concave surface, 1022, 1022a, 1022b, 1022c, 1022d, 1112, 1122, 1132, 1142...inlet, 1 024·1024a·1024b·1024c·1024d·1024x·1024y·1114·1124·1134·1144·1149a·1224... injection nozzle, 1126: non-porous part, 1128: porous part, 1136·1138·1141·1149: member, H: maximum depth, S1...first surface, S2...second surface, S3...side surface, L...laser light, M...sample, O...center point, C1...first circle, C2...second circle, C3...third circle, P1: first region, P2: second region, J1·J2·Q1·Q2: part, R·R1·R2·R3: radius

Claims

1. A glass manufacturing apparatus for manufacturing glass by cooling heated and melted glass raw materials suspended by gas, comprising: a holding member used to face the glass raw material; a laser device that irradiates the glass raw material with laser light, The holding member is a plurality of first through holes through which the gas can pass; a plurality of second through holes that are different from the first through holes and through which the gas can pass; a first surface from which the gas can be ejected, The first surface is a first region including a plurality of first injection ports which are end surfaces of the plurality of first through holes; a second region including a plurality of second injection ports that are end faces of the plurality of second through holes, When viewed from above on the first surface, the first region is inside the second region, a ratio (W1) of an area of ​​the plurality of first injection ports to an area of ​​the first region and a ratio (W2) of an area of ​​the plurality of second injection ports to an area of ​​the second region satisfy a relationship of W1<W2, the plurality of first through holes and the plurality of second through holes are substantially parallel to each other, the laser device irradiates the glass raw material with the laser light without allowing the laser light to pass through the first surface; Glass manufacturing equipment.

2. A glass manufacturing apparatus for manufacturing glass by cooling glass raw materials that are suspended in gas and heated and melted, comprising: a holding member used to face the glass raw material, The holding member is a plurality of first through holes through which the gas can pass; a plurality of second through holes that are different from the first through holes and through which the gas can pass; a first surface from which the gas can be ejected, The first surface is a first region including a plurality of first injection ports which are end surfaces of the plurality of first through holes; a second region including a plurality of second injection ports that are end faces of the plurality of second through holes, When viewed from above on the first surface, the first region is inside the second region, a ratio (W1) of an area of ​​the plurality of first injection ports to an area of ​​the first region and a ratio (W2) of an area of ​​the plurality of second injection ports to an area of ​​the second region satisfy a relationship of W1<W2, the plurality of first through holes and the plurality of second through holes are substantially parallel to each other, The length of the plurality of first through holes is shorter than the length of the plurality of second through holes. Glass manufacturing equipment.

3. A glass manufacturing apparatus for manufacturing glass by cooling heated and melted glass raw materials suspended by gas, comprising: a holding member used to face the glass raw material; a laser device that irradiates the glass raw material with laser light, The holding member is a plurality of first through holes through which the gas can pass; a plurality of second through holes that are different from the first through holes and through which the gas can pass; a first surface from which the gas can be ejected, The first surface is a first region including a plurality of first injection ports which are end surfaces of the plurality of first through holes; a second region including a plurality of second injection ports that are end faces of the plurality of second through holes, When viewed from above on the first surface, the first region is inside the second region, a ratio (T1) of the number of the plurality of first injection ports to an area of ​​the first region and a ratio (T2) of the number of the plurality of second injection ports to an area of ​​the second region satisfy the relationship T1<T2, the plurality of first through holes and the plurality of second through holes are substantially parallel to each other, the laser device irradiates the glass raw material with the laser light without allowing the laser light to pass through the first surface; Glass manufacturing equipment.

4. A glass manufacturing apparatus for manufacturing glass by cooling glass raw materials that are suspended by gas and heated and melted, comprising: a holding member used to face the glass raw material, The holding member is a plurality of first through holes through which the gas can pass; a plurality of second through holes that are different from the first through holes and through which the gas can pass; a first surface from which the gas can be ejected, The first surface is a first region including a plurality of first injection ports which are end surfaces of the plurality of first through holes; a second region including a plurality of second injection ports that are end faces of the plurality of second through holes, When viewed from above on the first surface, the first region is inside the second region, a ratio (T1) of the number of the plurality of first injection ports to an area of ​​the first region and a ratio (T2) of the number of the plurality of second injection ports to an area of ​​the second region satisfy the relationship T1<T2, the plurality of first through holes and the plurality of second through holes are substantially parallel to each other, The length of the plurality of first through holes is shorter than the length of the plurality of second through holes. Glass manufacturing equipment.

5. a ratio (W1) of an area of ​​the plurality of first injection ports to an area of ​​the first region and a ratio (W2) of an area of ​​the plurality of second injection ports to an area of ​​the second region satisfy a relationship of W1<W2; The glass manufacturing apparatus according to claim 3 or 4.

6. a ratio (W1 / W2) of a ratio (W2) of an area of ​​the plurality of second injection ports to an area of ​​the second region to a ratio (W1) of an area of ​​the plurality of first injection ports to an area of ​​the first region is 0.05 to 0.7; The glass manufacturing apparatus according to claim 1, 2 or 5.

7. a ratio (T1 / T2) of a ratio (T2) of the number of the plurality of second injection ports to an area of ​​the second region to a ratio (T1) of the number of the plurality of first injection ports to an area of ​​the first region is 0.05 to 0.5; The glass manufacturing apparatus according to any one of claims 3 to 6.

8. At least a part of the holding member is made of stainless steel (SUS), silicon carbide (SiC), alumina (Al ２ O ３ ), zirconia (ZrO ２ ), duralumin, copper (Cu), and carbon (C), The glass manufacturing apparatus according to any one of claims 1 to 7.

9. The radius of the first injection port is 0.2 mm or less, The radius of the second injection port is 0.5 mm or less. The glass manufacturing apparatus according to any one of claims 1 to 8.

10. At least a portion of the retaining member is porous. The glass manufacturing apparatus according to any one of claims 1 to 9.

11. the holding member has a porous member, and the porosity of the porous member in a portion corresponding to the first region is lower than the porosity of the porous member in a portion corresponding to the second region; The glass manufacturing apparatus according to any one of claims 1 to 10.

12. The holding member includes, at least in part, a member made of a porous material and a member made of a metal material. The glass manufacturing apparatus according to claim 10 or 11.

13. The pore diameter of the porous material is 100 μm or less. The glass manufacturing apparatus according to any one of claims 10 to 12.

14. The gas is ejected in a substantially horizontal direction that is substantially perpendicular to the direction of gravity. The glass manufacturing apparatus according to any one of claims 1 to 13.

15. the holding member has an injection port located above the first surface, which injects gas in a substantially horizontal direction substantially perpendicular to the direction of gravity; The glass manufacturing apparatus according to any one of claims 1 to 14.

16. The first surface is a substantially circular area when viewed from above the holding member. The glass manufacturing apparatus according to any one of claims 1 to 15.

17. the first region is a region including a center or a center of gravity in a top view of the first surface; The glass manufacturing apparatus according to any one of claims 1 to 16.

18. the first region is at least a part of a substantially circular region having a radius from a center point of r or less (r<R, R is the radius of the first surface in a top view of the first surface), the second region is at least a part of a substantially annular region having an inner periphery with a radius equal to or greater than the r when viewed from above on the first surface; The glass manufacturing apparatus according to any one of claims 1 to 17.

19. the first region is at least a part of a substantially circular region having a radius from a center point of 0.2R or less, where R is a radius of the first surface, when viewed from above the first surface; the second region is at least a part of a substantially annular region when viewed from above the first surface, the radius of the inner periphery of the substantially annular region is 0.2R or more relative to the radius (R) of the first surface; The glass manufacturing apparatus according to any one of claims 1 to 18.

20. The radius of the outer periphery of the approximately annular region is 0.9R or less with respect to the radius (R) of the first surface.

20. The glass manufacturing apparatus of claim 19.

21. The first region is at least a part of a substantially circular region having a radius from a center point of 0.2R or less, where R is a radius of the first surface, when viewed from above the first surface. The glass manufacturing apparatus according to any one of claims 1 to 18.

22. the second region is at least a part of a substantially annular region when viewed from above the first surface, the radius of the inner periphery of the substantially annular region is 0.4R or more with respect to the radius (R) of the first surface, The radius of the outer periphery of the approximately annular region is 0.9R or less with respect to the radius (R) of the first surface. The glass manufacturing apparatus according to any one of claims 1 to 19.

23. The first region is at least a part of a substantially circular region having a radius of 3 mm or less from a center point when viewed from above on the first surface. The glass manufacturing apparatus according to any one of claims 1 to 22.

24. the second region is at least a part of a substantially annular region when viewed from above the first surface, The radius of the inner circumference of the substantially annular region is 3 mm or more, The radius of the outer periphery of the approximately circular ring region is 9 mm or less. The glass manufacturing apparatus according to any one of claims 1 to 23.

25. the first surface has, in a top view, a first circular region, a second circular region having a radius equal to or greater than the radius of the first circle, and a third circular region having a radius larger than the radius of the second circle, which are arranged concentrically; the first region is at least a part of the first circular region, the second region is at least a part of a substantially circular region obtained by excluding the second circular region from the third circular region; The glass manufacturing apparatus according to any one of claims 1 to 24.

26. The second region is not adjacent to the first region. The glass manufacturing apparatus according to any one of claims 1 to 25.

27. a gas introduction surface having an inlet for introducing the gas is provided on a side surface of the holding member or on a surface opposite to the first surface; The glass manufacturing apparatus according to any one of claims 1 to 26.

28. the first surface has a plurality of first injection ports and a plurality of second injection ports, each of which communicates with one introduction port; 28. The glass manufacturing apparatus of claim 27.

29. At least one of the first injection ports and the second injection ports of the first surface communicates with a plurality of introduction ports.

28. The glass manufacturing apparatus of claim 27.

30. The radius (R) of the first surface is 5 to 10 mm when viewed from above. The glass manufacturing apparatus according to any one of claims 1 to 29.

31. The maximum depth (H) of the first surface is 4 to 10 mm in a cross-sectional view of the first surface. The glass manufacturing apparatus according to any one of claims 1 to 30.

32. A glass manufacturing apparatus as described in any one of claims 1 to 31, wherein the gas flow rate ejected from the second region is greater than the gas flow rate ejected from the first region.

33. A glass manufacturing apparatus as described in any one of claims 1 to 32, wherein the length of the second through hole gradually increases as it moves outward when viewed from above on the first surface.

34. A method for producing glass, comprising producing glass by the glass producing apparatus according to any one of claims 1 to 33.

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