JP2008189478A - Multiple flow path - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow path for molten glass flowing where an optical glass gob having uniform temperature distribution, not having optical defects such as "striae" and the like and having excellent optical quality can be manufactured. <P>SOLUTION: In the flow path to transport molten glass melted in a glass melting furnace from the glass melting furnace, at least one inner cylindrical pipe is located to the flow path direction in an outer cylindrical pipe constituting the side wall of the flow path. It is characterized by that the ratio of the cross sectional area of the inner cylindrical pipe to that of the outer cylindrical pipe is 2/3 or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a multiple flow channel suitable for outflow of molten glass, particularly for flowing out molten glass from a glass melting furnace, and in particular, a multiple flow channel for outflow of molten glass suitable for forming a glass gob having a uniform temperature distribution. About.

  With the widespread use of digital cameras and camera-equipped mobile phones, there is an increasing demand for glass optical elements such as aspheric lenses that constitute an imaging optical system. In addition, with the widespread use of DVD devices and personal computers, there is an increasing demand for small glass lenses that guide light beams for reading and writing data on optical recording information recording media.

  Conventionally, optical glass elements such as glass lenses have been manufactured by processing a glass block having a predetermined size into a predetermined shape by grinding and polishing. However, the manufacture of a lens having an aspherical shape requires a very high-precision processing technique, which requires a lot of processing time for both grinding and polishing and requires a great deal of cost.

  Thus, a glass precision press molding method (also referred to as a mold optics molding method) has been proposed as a method for producing such an optical element made of glass with high productivity and high accuracy.

  In this precision press molding method, a glass preform called a preform having a predetermined shape and weight, a smooth surface and high internal quality is produced. The preform is heated and precision press-molded to mold the optical element. In order to improve the productivity of this optical element, it is also necessary to increase the productivity of the preform.

  Incidentally, as a method for producing a preform with high productivity, there is a method called a hot preform molding method as disclosed in Patent Document 1. The hot preform molding method is a method in which a predetermined amount of glass is separated from molten glass flowing out from a nozzle to form a glass gob, and the glass gob is molded to obtain a preform. In this method, a homogeneous molten glass that does not contain bubbles is produced, flows out from a heat-resistant nozzle called a nozzle at a constant flow rate, and a molten glass gob having a predetermined weight is separated from the flowing molten glass flow. Is molded into a preform in the process of cooling.

In the hot preform molding method, it is not necessary to cut or polish the glass block, so that the process can be simplified and a large amount of preforms having a constant weight can be produced. Further, since there is no need for machining, there is a feature that glass waste such as sludge can be dispensed with.
Japanese Examined Patent Publication No. 7-51446

  As described above, the hot preform molding method is an excellent method, but when the molten glass is caused to flow out from the outflow nozzle, a temperature distribution is generated in the tube of the outflow nozzle, and thus the formed glass gob also has a temperature distribution. That is, when the molten glass flows from the glass melting furnace to the outflow nozzle, since the inside of the glass melting furnace is in a quasi-static state, the molten glass flowing from here has a substantially uniform flow rate as shown in FIG. And the temperature distribution is substantially uniform.

  However, due to the viscous resistance with the tube wall, the flow velocity distribution in the tube is slower near the tube wall than near the tube center, resulting in a flow velocity distribution as shown in FIG.

  As the flow further proceeds in the outflow nozzle tube, the velocity distribution becomes more prominent, and the state as shown in FIG. 12 (c) is obtained. Finally, as shown in FIG. 12 (d), a parabolic shape is obtained. Has a velocity distribution.

  In addition, although knowledge about such a flow velocity distribution is obtained from an experiment related to a general liquid pipe flow at room temperature, from the viscous fluid theory, the same phenomenon is observed in the molten glass outflow pipe, It is thought that it has occurred.

  Also, near the tube wall, heat is radiated and the temperature drops, but the velocity distribution in the outflow nozzle tube slows down the flow of the molten glass flowing near the tube wall, thereby further promoting the temperature drop. The On the other hand, near the center of the pipe, the flow rate is faster than near the pipe wall, so there is little decrease in temperature. For this reason, the temperature distribution at the outlet of the outflow nozzle has a substantially parabolic temperature distribution in which the temperature near the center of the pipe is higher than the temperature near the pipe wall, similar to the velocity distribution.

  For this reason, as shown in FIG. 13, the glass gob formed at the outlet has a temperature distribution in which both end portions have a temperature lower than that near the center, and the temperature distribution of the glass gob Differences occur in evaporation of easily volatile components in the glass from the surface layer of the molten glass at both end portions, and an optical defect called “striation” due to this occurs. In FIG. 13, the shading is a schematic representation of the temperature distribution, and indicates that the temperature increases as the density changes from dark to light.

  In the method of directly molding a desired optical element by press molding this glass gob with high precision, if there is a defect such as striae on the surface or surface layer of the glass gob, the optical obtained by molding this glass gob Since defects such as striae also occur in the element, it is necessary to manufacture a glass gob free from defects such as striae with a very high yield with high accuracy.

  That is, an object of the present invention is to solve the production of an optical glass gob having an extremely high optical quality that is free from optical defects such as “striation” that cannot be solved by the prior art.

  And the objective of this invention is providing the flow path for molten glass outflow which can manufacture the optical glass gob with which temperature distribution was equalized and was excellent in optical quality.

  As a result of diligent research to solve the above problems, the present inventor has an inner diameter (channel cross-sectional area) at a position where the molten glass flows at the highest temperature in the direction of the outer cylinder of the channel of the molten glass. By disposing at least one small inner cylinder, the flow of molten glass in the part where the temperature inside the inner cylinder is high is suppressed and the flow rate becomes slow. It has been found that the temperature is lowered by the molten glass flowing near the wall of the tube and the temperature distribution becomes more uniform, and the present invention has been completed.

  More specifically, the present invention provides the following.

  (1) A flow path for transporting molten glass melted in a glass melting furnace from the glass melting furnace, wherein at least one inner cylinder is formed in the outer cylinder constituting the side wall of the flow path. Multiple flow paths arranged in the glass flow path direction.

  According to the aspect of (1), since the molten glass flows in the inner cylinder disposed in the flow direction of the outer cylinder, the flow path cross-sectional area of the inner cylinder is smaller than the flow path cross-sectional area of the outer cylinder. The flow rate of the molten glass flowing in the inner cylinder becomes slow. For this reason, by providing the inner cylinder in the part where the flow of the molten glass is fast and the temperature is high, the molten glass having a high temperature flows in the inner cylinder, the flow is suppressed and the flow velocity becomes slow, and the flow velocity in the inner cylinder is slow. The temperature is lowered by the molten glass flowing near the outer cylinder while it is flowing in, and the temperature difference between the molten glass flowing near the wall of the outer cylinder and the inner cylinder is reduced, and the temperature distribution is uniform. It becomes. Thus, since the part where the temperature of molten glass is high can be cooled by providing an inner cylinder, it is good to set it as the part where the flow of molten glass is quick as a position which arrange | positions an inner cylinder.

  While the flow of the molten glass usually has a velocity distribution in which the flow in the central part becomes the fastest while flowing out of the glass melting furnace and flowing in the flow path, it has a temperature distribution that the temperature is higher in the central part. . For this reason, it is preferable to install the inner cylinder in the central portion in the flow path direction because the above-described effect can be obtained more. In addition, when a plurality of inner tube tubes are provided, it is particularly preferable that they are arranged concentrically at the central portion in the flow path direction.

  (2) The multiple flow path according to (1), wherein a ratio between a flow path cross-sectional area of the inner cylinder and a flow path cross-sectional area of the outer cylinder is 2/3 or less.

  According to the aspect of (2), since the cross-sectional area of the inner cylinder is 2/3 or less of the cross-sectional area of the outer cylinder, the cross-sectional area of the inner cylinder is small, and the inner cylinder is melted. Glass flow is suppressed and slowed down. Thereby, the flow of the molten glass near the center in the outer tube is suppressed, and the temperature distribution at the outlet is made more uniform.

  (3) The multiple channel according to (1) or (2), wherein each annular portion channel area where the support member exists is 10% or more of each annular area.

  According to the aspect of (3), molten glass can flow without being disturbed by the support member. Here, the annular portion means a portion surrounded by the inner cylindrical tube and the outer cylindrical tube and / or a portion surrounded by adjacent inner cylindrical tubes, and is a portion serving as a flow path of the molten glass.

  (4) The multiple flow path according to any one of (1) to (3), wherein the inner cylinder is disposed such that a distal end portion thereof is located inside a distal end portion of the outer cylinder.

  When a predetermined amount of glass is separated from the molten glass flowing out, the molten glass is divided through a constricted state as shown in FIG. At this time, if the tip of the inner tube protrudes from the tip of the outer tube, the amount of heat and heat capacity around the inner tube change rapidly immediately after the glass is divided, so that the temperature of the inner tube fluctuates and is stable. Temperature control becomes difficult.

  On the other hand, according to the aspect (4), when the predetermined amount of glass is separated from the molten glass flowing out, the inner tube is present in a substantially steady flow, so that fluctuation of the surrounding heat amount and heat capacity occurs. Therefore, the temperature change of the inner tube can be suppressed. Here, the inside means the counter-flow outlet side (the front side of the outlet) of the outlet from which the molten glass flows out.

  (5) A method for manufacturing a hot formed body using the multiple flow path described in any one of (1) to (4).

  According to the aspect of (5), since the multiple flow path in any one of (1) to (4) can equalize the temperature distribution at the outlet of the molten glass, it can be melted from the glass melting furnace. By using it appropriately for the method of molding glass by flowing it out into a glass molding mold, the method of forming glass gob by outflowing and dropping molten glass, and press molding the glass gob, etc. It is possible to obtain a molded body free from optical defects such as the above.

  (6) The multiple flow path nozzle according to any one of (1) to (5), wherein the molten glass melted in the glass melting furnace is caused to flow out of the glass melting furnace.

  According to the aspect of (6), since the temperature distribution at the outlet of the molten glass where the flow of the molten glass becomes a multiple flow path is made uniform by the multiple tube nozzle, by using the multiple tube nozzle of the multiple flow path, A glass gob with a uniform temperature distribution is obtained, and in a method of forming molten glass from a glass melting furnace into a glass molding mold and a method of forming glass gob by flowing out and dropping molten glass, compared to conventional methods. A molded body free from optical defects such as “stria” can be obtained.

  In the multiple flow path of the present invention, an inner cylinder having a predetermined flow cross-sectional area is provided in a portion where the temperature of the molten glass is high in the outer cylinder constituting the flow path. It flows in the inner cylinder. For this reason, the flow of the molten glass in the high temperature part is suppressed, the flow rate becomes slow, the temperature difference with the molten glass flowing near the inner cylinder wall in the outer cylinder is reduced, and the temperature distribution at the outlet is uniform. It becomes. As a result, the temperature distribution is made uniform from the outlet and flows out, so that a glass gob with a uniform temperature distribution is obtained.

  Hereinafter, the present invention will be specifically described.

  The multiple flow path of the present invention is characterized in that at least one inner cylinder having a predetermined flow path cross-sectional area is disposed at the center in the flow path direction of the outer cylinder constituting the side wall of the flow path.

  Hereinafter, an embodiment of the multiple flow path of the present invention will be described in detail based on a multi-tube nozzle which is an embodiment of the multiple flow path of the present invention, but the present invention is not limited to the following embodiment. However, the present invention can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, description may be abbreviate | omitted suitably, However, The meaning of invention is not limited.

(First embodiment)
Hereinafter, the multiple flow path according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a multi-tube nozzle that is a multi-channel according to the first embodiment, FIG. 2 is a cross-sectional view of the multi-tube nozzle, and FIG. It is an arrow view, (b) is a BB line cross-sectional arrow view. FIG. 3 is a diagram for explaining the operation of the multiple flow path according to the first embodiment of the present invention.

  As shown in FIG. 1 and FIG. 2, a multi-tube nozzle 1 which is a multi-channel of the present invention is an outer cylinder tube 2 constituting a side wall of the nozzle 1, and a substantially fixed upper portion of the outer cylinder tube 2. A nozzle having a double-pipe structure comprising a circular plate-like support member 4 and one inner tube 3 disposed at a substantially central portion of the plate-like support member 4. 4, the inner tube 3 is fixedly disposed at a substantially central portion thereof by welding or the like, and further, a first hole 5 having substantially the same diameter as the tube 3 and communicating with the inner tube 3. Is formed.

  Further, the first annular portion 4a surrounded by the outer cylindrical tube 2 and the inner cylindrical tube 3 includes a plurality of second cylinders having the same diameter at substantially equal intervals along the outer periphery of the inner cylindrical tube 3. Holes 6 are formed (four in this embodiment). The multi-tube nozzle 1 is fixed and attached to a conduit pipe 7 through which molten glass flows out from the glass melting furnace by welding or the like. In addition, it is good also as a structure which can arrange | position the heat generating body 8 around the multi-tube nozzle 1, and can adjust temperature.

  Here, the cross-sectional shape of the outer tube 2 is not particularly limited to a circle, and the length and cross-sectional area of the outer tube 2 are any as long as they have the ability to meet the design specifications of the melting equipment. Can also be used. In addition, if the material has a thermal property that does not significantly corrode or evaporate even at a high temperature up to 1600 ° C, and is chemically difficult to react with molten glass, what is it? Although it can be used, specifically, platinum or an alloy thereof or gold or an alloy thereof can be used.

  The cross-sectional shape of the outer tube 2 is circular in this embodiment, but is not limited to this, and can be, for example, an ellipse, a substantially rectangular shape, or a substantially polygonal shape. Further, there is no problem as long as the tube thickness is a thickness that can maintain sufficient strength.

  Also, the inner tube 3 has a thermal property that does not significantly corrode or evaporate even at a high temperature up to 1600 ° C., and it is chemically difficult to react with the molten glass. Any material can be used, and specific examples thereof include platinum or an alloy thereof or gold or an alloy thereof. The cross-sectional shape is preferably the same as the cross-sectional shape of the outer tube 2.

  The flow passage cross-sectional area of the inner cylindrical tube 3 is appropriately set depending on the composition, temperature, etc. of the molten glass, but is preferably 2/3 or less, more preferably 1 with respect to the flow passage cross-sectional area of the outer tubular tube 2. / 2 or less, most preferably 1/4 or less. This is because if the flow path cross-sectional area of the inner cylindrical pipe 3 is larger than 2/3 of the flow path cross-sectional area of the outer cylindrical pipe 2, the flow rate in the inner cylindrical pipe 3 becomes larger than the annular portion flow rate. . On the other hand, if the cross-sectional area of the inner tube 3 is too small, it becomes difficult for the molten glass to flow through the inner tube 3, so the inner diameter of the inner tube 3 is preferably 0.2 mm or more as a lower limit. The thickness is preferably 0.5 mm or more, and most preferably 1 mm or more. Although the above description is based on the cross-sectional area of the flow path, the inner cylinder inner diameter is preferably 3/4 or less, more preferably 7/10 or less, and more preferably 1/2 or less of the inner cylinder pipe inner diameter. Most preferred.

  Further, the distal end portion of the inner cylindrical tube 3 is preferably located on the inner side (reverse outlet side of the multiple tube nozzle 1) than the distal end portion of the outer cylindrical tube 2. And the distance from the front-end | tip part of the inner cylinder pipe 3 to the front-end | tip part of the outer cylinder pipe 2 is based on the composition and temperature of molten glass, and the heat generating body 8 arrange | positioned around the multi-tube nozzle 1 similarly to an internal diameter. Although it is appropriately set depending on the heating method of the multi-tube nozzle 1 or the like, it is preferably at least 0 mm, more preferably 1.0 mm so that the inner tube 3 is not exposed from the outer tube 2 at least when the glass gob is separated. As described above, the thickness is most preferably 2.0 mm or more. Moreover, it is preferable that the temperature distribution made uniform by the inner tube 3 is a distance that does not return to a substantially parabolic temperature distribution again. In the present embodiment, the flow path of the outflow part is a multiple flow path, but the flow path before the outflow part may be a multiple flow path (not shown). However, as described above, it is most preferable that the flow path of the outflow portion is a multiple flow path.

  The plate-like support member 4 is for supporting the inner tube 3 in the outer tube 2, and has a thermal property that does not significantly corrode or evaporate even at high temperatures up to 1600 ° C. However, platinum or an alloy thereof, gold or an alloy thereof can be used, for example. Moreover, there is no problem as long as the thickness dimension is sufficient to hold the inner tube 3 and maintain a sufficient strength to withstand the flow of the molten glass.

  The second hole 6 is for temporarily stopping the flow of the molten glass by the plate-like support member 4, and is for transferring the stopped flow to the space between the inner tube 3 and the outer tube 2. A plurality of the first annular portions 4a of the support member 4 surrounded by the inner cylindrical tube 3 and the outer cylindrical tube 2 are arranged at substantially equal intervals along the outer periphery of the inner cylindrical tube 3 (4 in this embodiment). Formed). The diameter and the number of the second holes 6 depend on the inner diameters of the outer tube 2 and the inner tube 3 of the multi-tube nozzle 1, but the total opening area (annular shape) of the plurality of second holes 6 is not limited. It may be set as appropriate so that the partial channel area) is 10% or more, preferably 30% or more, and most preferably 50% or more of the annular area of the first annular portion 4a. Thereby, the resistance to the glass flow by the plate-like support member 4 is reduced, and an unnecessary change in the glass flow is prevented.

  The multiple tube nozzle 1 can be fixed to the outlet of the conduit pipe 7 by welding or the like, so that the temperature distribution of the molten glass flowing in the outer tube 2 can be made uniform as described below.

  As described above, at the outlet of the conduit pipe 7, when molten glass that has flowed out of the glass melting furnace (not shown) flows through the conduit pipe 7, near the central wall and the center of the conduit pipe 7. As shown in FIG. 12 (d), the part has a parabolic velocity distribution, and has a substantially parabolic temperature distribution in which the temperature in the central part is high. On the other hand, as shown in FIG. 3, the molten glass A flowing through the central portion of the outer tube 2 is attached to the outlet of the conduit pipe 7 by attaching the multi-tube nozzle 1 to the inner tube having a small channel cross-sectional area. It will flow in the pipe 3, and the flow velocity is suppressed. That is, as shown by the upper arrow in FIG. 3, the flow of the molten glass A is faster at the center of the tube than near the tube wall, but at the outlet of the inner tube 3 as shown by the lower arrow. The flow velocity in the center is slower than the flow velocity near the tube wall. For this reason, while the flow of the molten glass A at a high temperature flows in the inner tube 3 at a slow flow rate, the molten glass A is cooled by the molten glass A flowing in the outer tube, the temperature is lowered, and the interior of the outer tube is reduced. The temperature difference with the flowing molten glass A is reduced, and the temperature distribution of the molten glass A in the outer tube 2 is made uniform as shown by the shading in FIG. 3 (in FIG. 3, the shading schematically represents the temperature distribution). It shows that the temperature increases from dark to light).

  Accordingly, the glass gob B formed at the outlet of the multi-tube nozzle 1 is more uniform without having a substantially parabolic temperature distribution at both ends and the center near the tube wall. Since there is no difference in the evaporation of easily volatile components from the surface layer of the glass gob B at the center and both ends, an optical defect called “striated” is much less likely to occur than before.

  In the present embodiment, the inner tube 3 of the multi-tube nozzle 1 has been described as being provided at a substantially central portion of the outer tube 2. However, the position where the inner tube 3 is provided is the shape of the outer tube 2, etc. Although it depends, it should just be installed in the flow part with high temperature by the flow path of molten glass, and it is not limited to a center part in particular. The same applies to the following embodiments.

(Second embodiment)
Next, the multiple flow path according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a vertical cross-sectional view of a multi-tube nozzle which is a multi-channel according to the second embodiment, FIG. 5 is a cross-sectional view of the multi-tube nozzle, and FIG. It is an arrow view, (b) is a BB line cross-sectional arrow view. In the second embodiment, in the first embodiment, the means for supporting the inner tube 3 of the multi-tube nozzle is changed to a plate-like support member 4 and changed to a rod-like support member 10.

  As shown in FIGS. 4 and 5, the multi-tube nozzle 1, which is a multi-channel of the present invention, is arranged at an outer cylindrical tube 2 constituting the side wall of the nozzle 1 and at a substantially central portion of the outer cylindrical tube 2. 5 is a double tube structure nozzle comprising an inner tube 3 and a rod-like support member 10 that supports the inner tube 3, and the rod-like support member 10 has one end as shown in FIG. Is fixed to the outer tube 2 by welding or the like, and the other end is connected to the inner tube 3 by welding or the like. In addition, it is desirable that the number of the rod-shaped support members 10 is at least one, preferably a plurality (two in this embodiment).

  Here, the rod-shaped support member 10 is for supporting the inner tube 3 in the outer tube 2 and is thermally prevented from being significantly corroded or evaporated even at a high temperature up to 1600 ° C. The material is not particularly limited as long as it is a material that has a unique property and hardly chemically reacts with the molten glass. For example, platinum or an alloy thereof, or a rod-shaped member made of gold or an alloy thereof can be used. And it is preferable to devise such as making it a cross-sectional shape such as a streamline that does not obstruct the flow of the molten glass. Moreover, it is preferable that a cross-sectional area is 90% or less of the area of the annular portion surrounded by the inner tube and the outer tube. Thereby, the resistance to the glass flow by the rod-like support member 10 is reduced, and unnecessary changes in the glass flow are prevented.

  Since the other configuration other than the rod-like support member 10 is the same as that of the first embodiment, the description thereof is omitted.

(Third embodiment)
Next, a multiple flow path according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a longitudinal sectional view of a multi-tube nozzle which is a multi-channel according to the third embodiment of the present invention, FIG. 7 is a cross-sectional view of the multi-tube nozzle, and FIG. It is an A-line cross-sectional arrow view, (b) is a BB line cross-sectional arrow view.

  The multi-tube nozzle 1 which is a multi-channel of the present invention has a triple tube structure in which the inner tube 3 of the multi-tube nozzle is two in the first embodiment, and is shown in FIGS. As shown in FIG. 2, the outer cylindrical tube 2 constituting the side wall of the nozzle 1 and the two inner cylindrical tubes disposed substantially at the center of the outer cylindrical tube 2, that is, the first inner cylindrical tube 3a located inside. And a nozzle having a triple tube structure comprising a second inner cylindrical tube 3b positioned on the outer side and a substantially circular plate-like support member 4 fixed to the upper portion of the outer cylindrical tube 2. The support member 4 is provided with a first inner tube 3a and a second inner tube 3b fixed at the center thereof by welding or the like. The first inner tube 3a and the second inner tube 3b are preferably arranged concentrically.

  Further, a central portion of the support member 4 communicates with the first inner tube 3a, a first hole 5 having a diameter substantially the same as the inner diameter of the first inner tube 3a, the first inner tube 3a, The second annular portion 4b surrounded by the second inner tube 3b is formed at substantially equal intervals along the outer periphery of the first inner tube 3a and the inner periphery of the second inner tube 3b. A plurality of third holes 9 are formed (four in this embodiment).

  Further, the first annular portion 4a surrounded by the outer cylindrical tube 2 and the second inner cylindrical tube 3b located on the outside is provided along the outer periphery of the second inner cylindrical tube 3b and the inner periphery of the outer cylindrical tube 2. Thus, a plurality of second holes 6 having the same diameter are formed at substantially equal intervals (eight in the present embodiment). The multi-tube nozzle 1 is fixed and attached to a conduit pipe 7 through which molten glass flows out from the glass melting furnace by welding or the like. In addition, it is good also as a structure which can arrange | position the heat generating body 8 around the multi-tube nozzle 1, and can adjust temperature.

  Here, the relationship between the inner diameters of the first inner tube 3a and the second inner tube 3b is appropriately determined depending on the composition and temperature of the molten glass, but the inner diameter of the first inner tube 3a is first. Preferably, it is 3/4 or less, more preferably 7/10 or less, and most preferably 1/2 or less with respect to the inner diameter of the second inner tube 3b. (When the flow path cross-sectional area is used as a reference, the inner cylinder flow path cross-sectional area is preferably 2/3 or less, more preferably 1/2 or less, and most preferably 1/4 or less of the outer cylinder flow path cross-sectional area.) When the inner diameter of the first inner cylinder pipe 3a located on the inner side is larger than 3/4 of the inner diameter of the second inner cylinder pipe 3b located on the outer side, the flow rate in the first inner cylinder pipe 3a becomes an annular portion. This is because it becomes larger than the flow rate. On the other hand, if the inner diameter of the first inner tube 3a is too small, it becomes difficult for the molten glass to flow in the first inner tube 3a. Therefore, the inner diameter of the first inner tube 3a is preferably set as the lower limit. Is 0.2 mm or more, more preferably 0.5 mm or more.

  Further, the relationship between the inner diameter of the second inner cylindrical tube 3b located on the outer side and the inner diameter of the outer cylindrical tube 2 is also appropriately determined according to the composition, temperature, etc. of the molten glass. The inner diameter is preferably 3/4 or less, more preferably 1/2 or less with respect to the inner diameter of the outer tube 2. (When the flow path cross-sectional area is used as a reference, the inner cylinder flow path cross-sectional area is preferably 2/3 or less, more preferably 1/2 or less, and most preferably 1/4 or less of the outer cylinder flow path cross-sectional area.) This is because if the inner diameter of the second inner cylindrical tube 3b is larger than 3/4 of the inner diameter of the outer cylindrical tube 2, the flow rate in the second inner cylindrical tube 3b becomes larger than the annular portion flow rate. On the other hand, if the inner diameter of the second inner cylindrical tube 3b is too small, it is difficult to dispose the first inner cylindrical tube 3a inside. Therefore, the lower limit is preferably 0.5 mm or more.

  Further, the size and number of the plurality of third holes 9 formed in the second annular portion 4b surrounded by the first inner tube 3a and the second inner tube 3b are set to a plurality of the number of the third holes 9b. The total opening area of the three holes 9 (corresponding to the annular portion channel area of the annular portion surrounded by the first inner cylindrical tube 3a and the second inner cylindrical tube 3b) is 10% of the annular area of the annular portion 4b. The content may be appropriately set so as to be 30% or more, and most preferably 50% or more. Further, the size and number of the second holes 6 depend on the inner diameters of the outer tube 2, the first inner tube 3a, and the second inner tube 3b of the multi-tube nozzle 1, but there are a plurality of second holes 6. The total opening area of the second hole 6 (corresponding to the annular portion channel area of the annular portion surrounded by the second inner cylindrical tube 3b of the annular portion surrounded by the outer cylindrical tube 2) is the outer cylindrical tube 2. And 10% or more, preferably 30% or more, and most preferably 50% or more of the annular area of the first annular portion 4a surrounded by the second inner cylindrical tube 3b located outside. That's fine. Thereby, the resistance to the glass flow by the plate-like support member 4 is reduced, and an unnecessary change in the glass flow is prevented.

  The distal end portions of the first inner cylindrical tube 3a and the second inner cylindrical tube 3b are located on the inner side (reverse outlet side of the multiple tube nozzle 1) than the distal end portion of the outer cylindrical tube 2, as shown in FIG. Is preferred. And the distance from the front-end | tip part of the 1st inner cylinder pipe | tube 3a and the 2nd inner-cylinder pipe | tube 3b to the front-end | tip part of the outer cylinder pipe 2 is the composition and temperature of a molten glass similarly to an internal diameter, or the multiple tube nozzle Although it is appropriately set depending on the heating method of the multi-tube nozzle 1 by the heating element 8 disposed around, at least the inner cylindrical tube 3a and the second inner cylindrical tube 3b are separated from the outer cylindrical tube 2 when the glass gob is separated. The thickness is preferably 0 mm or more, more preferably 1.0 mm or more, and most preferably 2.0 mm or more so as not to be exposed. Moreover, it is preferable that the temperature distribution made uniform by the first inner tube 3a and the second inner tube 3b is a distance that does not return to a substantially parabolic temperature distribution again.

  It should be noted that the inner diameter of the first inner tube 3a located on the inner side and the second inner tube 3b located on the outer side, the distance between the tips, the first hole 5 and the second hole formed in the support member 4. The relationship such as the size of 6 is the same even when there are three or more inner tube 3. That is, the inner cylinder pipe located inside the adjacent inner cylinder pipes 3 and the inner cylinder pipe located outside are configured in this relationship.

  In addition, since the cross-sectional shape, material, etc. of the outer cylinder pipe 2, the 1st inner cylinder pipe 3a and the 2nd inner cylinder pipe 3b, and the support member 4 are the same as that of 1st embodiment, description is abbreviate | omitted. .

  As described above, by providing the plurality of inner cylindrical tubes 3, the flow of the molten glass is divided into multiple stages, so that a more uniform temperature distribution can be obtained. In particular, an outer tube having a large inner diameter is preferable because it can be controlled in multiple stages.

(Fourth embodiment)
Next, a multiple flow path according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a vertical cross-sectional view of a multi-tube nozzle which is a multi-channel according to a fourth embodiment of the present invention, FIG. 9 is a cross-sectional view of the multi-tube nozzle, and FIG. It is an A-line cross-sectional arrow view, (b) is a BB line cross-sectional arrow view. In the fourth embodiment, the means for supporting the first inner tube 3a and the second inner tube 3b of the multi-tube nozzle 1 is changed to the plate-like support member 4 in the third embodiment. The rod-shaped support member 10 is changed.

  As shown in FIGS. 8 and 9, the multi-tube nozzle 1, which is a multi-channel of the present invention, has an outer tube 2 constituting the side wall of the multi-tube nozzle 1 and a substantially central portion of the outer tube 2. Two arranged inner cylinder pipes, that is, a first inner cylinder pipe 3a positioned inside and a second inner cylinder pipe 3b positioned outside, a first inner cylinder pipe 3a and a second inner cylinder. It is a nozzle of a triple pipe structure comprising a rod-like support member 10 that supports the tube 3b, and the rod-like support member 10 is fixed to the outer tube 2 by welding or the like, as shown in FIG. 9 (a). The other end is connected to the first inner tube 3a and the second inner tube 3b by welding or the like. The first inner tube 3a and the second inner tube 3b are preferably arranged concentrically. Further, the number of the rod-like support members 10 is preferably at least one, preferably a plurality (four in this embodiment).

  Here, the rod-shaped support member 10 is for supporting the first inner tube 3a and the second inner tube 3b in the outer tube 2, and as in the second embodiment, Although it is not particularly limited as long as it has a thermal property that does not significantly corrode or evaporate even at high temperatures up to 1600 ° C. and is chemically difficult to react with molten glass, for example, Platinum or its alloy or gold or its rod-shaped member can be used. The cross-sectional shape and area of the rod-shaped support member 10 are also the same as in the second embodiment.

  Since the other configuration other than the rod-like support member 10 is the same as that of the third embodiment, the description thereof is omitted.

  The multi-tube nozzles having the double tube structure and the triple tube structure have been described above, but the present invention is not limited to this, and the inner tube may be three or more multi-tube nozzles.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.

<Example 1>
The temperature distribution of the outflow glass at the outlet of the nozzle was measured using the double tube nozzle having a double structure, which is the multiple flow path according to the first embodiment described above. Further, as a comparative example, the temperature distribution of the outflow glass at the outlet of the conduit pipe when it was discharged from the conduit pipe was measured without using a multi-tube nozzle. The results are shown in FIGS. The specifications of the used multi-tube nozzle are as follows. The temperature at the nozzle outlet was measured using an infrared camera.

(Multi-tube nozzle specifications)
Outer cylinder tube: platinum alloy cylindrical tube with outer diameter of 7 mm, inner diameter of 6 mm and length of 6.6 mm Inner cylinder tube; platinum alloy cylindrical tube with outer diameter of 3.0 mm, inner diameter of 1.0 mm and length of 3 mm Is disposed in the center of the outer tube. Support member; plate member made of platinum having a diameter of 6 mm and a thickness of 1.0 mm First hole; 1 mm diameter through hole Second hole; 1 mm diameter through hole 4 Individual formation

  FIG. 10 shows the result when molten glass is allowed to flow out (temperature condition 1) when the indicated temperature of a thermocouple (not shown) installed on the outer wall of the outer tube immediately above the outlet is set to about 1100 ° C. FIG. 11 shows the result when the molten glass is flowed out at a temperature of about 1060 ° C. (temperature condition 2). 10 and 11, the horizontal axis indicates the distance from the center of the outlet, and the vertical axis indicates the temperature (relative temperature).

  When the molten glass was caused to flow out using the multiple tube nozzle of Example 1, when the molten glass was discharged at a temperature of about 1100 ° C. in the vicinity of the center of the outlet, compared to the case where the multiple tube nozzle of the comparative example was not used ( Under the temperature condition 1), the temperature decreased about 20 ° C. at the maximum, and it was confirmed that the temperature distribution was uniform. In addition, when the molten glass was allowed to flow out at about 1060 ° C. (temperature condition 2), the temperature decreased about 15 ° C. at the maximum, and it was confirmed that the temperature distribution was uniform.

It is a longitudinal cross-sectional view of the multiple tube nozzle which is the multiple flow path which concerns on 1st embodiment of this invention. It is a cross-sectional view of the multi-tube nozzle shown in FIG. 1, (a) is a cross-sectional view taken along line AA, and (b) is a cross-sectional view taken along line BB. It is a figure explaining the effect | action of the multiple flow path which concerns on 1st embodiment of this invention. It is a longitudinal cross-sectional view of the multiple tube nozzle which is the multiple flow path which concerns on 2nd embodiment of this invention. It is a cross-sectional view of the multi-tube nozzle shown in FIG. 4, where (a) is a cross-sectional view taken along line AA, and (b) is a cross-sectional view taken along line BB. It is a longitudinal cross-sectional view of the multiple tube nozzle which is the multiple flow path which concerns on 3rd embodiment of this invention. It is a cross-sectional view of the multi-tube nozzle shown in FIG. 6, (a) is a cross-sectional view taken along the line AA, and (b) is a cross-sectional view taken along the line BB. It is a longitudinal cross-sectional view of a multiple tube nozzle provided with the multiple flow path which concerns on 4th embodiment of this invention. It is a cross-sectional view of the multi-tube nozzle shown in FIG. 8, (a) is a cross-sectional view taken along line AA, and (b) is a cross-sectional view taken along line BB. It is a figure (outlet temperature 1100 degreeC) which shows the comparison of the temperature distribution of the outflow glass in the outflow port of a conventional nozzle and a double tube nozzle. It is a figure (outlet temperature 1060 degreeC) which shows the comparison of the temperature distribution of the outflow glass in the outflow port of a conventional nozzle and a double tube nozzle. It is a figure explaining the change of the velocity distribution of the molten glass which flows in the outflow nozzle. It is a figure explaining the effect | action of a conventional nozzle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multiple tube nozzle 2 Outer tube 3 Inner tube 4 Plate-shaped support member 5 1st hole 6 2nd hole 7 Conduit pipe 8 Heating element 9 3rd hole 10 Rod-shaped support member

Claims (6)

A flow path for transporting molten glass melted in a glass melting furnace,
A multiple flow path in which at least one inner cylinder is disposed in a flow path direction of the molten glass in an outer cylinder constituting a side wall of the flow path.   The multiple flow path according to claim 1, wherein a ratio of an inner diameter of the inner cylinder and a cross-sectional area of the outer cylinder is 2/3 or less.   3. The multi-channel according to claim 1, wherein each annular portion channel area where the support member is present is 10% or more of each annular area.   The multiple flow path according to any one of claims 1 to 3, wherein the inner cylinder is disposed such that a distal end portion thereof is located inside a distal end portion of the outer cylinder.   A method for producing a hot-formed body using the multiple flow path according to any one of claims 1 to 4.   6. The multi-passage nozzle according to claim 1, wherein the molten glass melted in the glass melting furnace is caused to flow out of the glass melting furnace.

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