JP7535223B2 - Glass fiber manufacturing apparatus and manufacturing method - Google Patents

Description

The present invention relates to an apparatus and method for manufacturing glass fibers, and more specifically to an apparatus and method for manufacturing glass fibers with irregular cross sections that have flat cross sections.

As a type of glass fiber, irregular cross-section glass fiber with a flat cross-sectional shape is known (see Patent Document 1). Fiber-reinforced plastics (FRP) obtained by kneading irregular cross-section glass fiber with resin to form a composite have high strength, so irregular cross-section glass fiber is used in various fields, such as as fibers for FRP.

Here, modified cross-section glass fibers can be produced, for example, by the following method.

Irregular cross-section glass fiber is manufactured using an apparatus equipped with a feeder for circulating molten glass produced in a glass melting furnace or the like, and a bushing arranged below the feeder. The bushing is equipped with many nozzles, and the nozzle holes of each nozzle are formed into a flat shape (oval, elliptical, etc.). Irregular cross-section glass fiber is manufactured by filling the entire flow path from inside the feeder to the nozzle holes of the bushing with molten glass, allowing the molten glass to flow out of the nozzle holes of each nozzle, and cooling the flowed-out molten glass while drawing it out.

International Publication No. 2018/020743

However, the above method has the following problems:

When molten glass flows out of the nozzle hole, the surface tension of the glass causes the glass to deform in a direction that reduces its surface area. In other words, the glass deforms so that the cross section becomes a perfect circle. Therefore, it is not easy to mold irregular cross-section glass fibers with a high flattening ratio. One possible solution to this problem is to lower the temperature of the molten glass flowing out of the nozzle hole in order to increase the viscosity of the molten glass and suppress deformation due to surface tension. However, this solution increases the viscosity of the molten glass, making it difficult to flow it out of the nozzle hole. Therefore, when manufacturing irregular cross-section glass fibers, improvements are needed to make it easier for the molten glass to flow out of the nozzle hole. However, such improvements place a load on the bushing. Therefore, it is desirable to manufacture irregular cross-section glass fibers with a high flattening ratio without increasing the load on the bushing.

In light of the above circumstances, the technical objective of the present invention is to make it possible for molten glass to easily flow out of the nozzle hole when producing modified cross-section glass fiber, while avoiding excessive load on the bushing.

The present invention, which aims to solve the above problems, is a glass fiber manufacturing device that includes a feeder for circulating molten glass, and a bushing with a flat nozzle hole disposed below the feeder, and produces irregular cross-section glass fiber by causing the molten glass supplied from the feeder to the bushing to flow out of the nozzle hole while the entire flow path from inside the feeder to the nozzle hole of the bushing is filled with molten glass, and is configured so that the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder is 0.3 m to 1.5 m.

In this device, the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder is 1.5 m or less, so that the pressure acting on the bushing from the molten glass can be kept within a range where the load on the bushing is not excessive. Furthermore, the height difference is 0.3 m or more, so that a pressure (head pressure) large enough to easily make the molten glass flow out of the nozzle hole can be secured. From the above, this device can easily make the molten glass flow out of the nozzle hole when manufacturing irregular cross-section glass fiber, and can suppress excessive load on the bushing. In addition, this device can achieve the following effects. That is, since excessive load on the bushing can be avoided, it is possible to increase the number of nozzle holes provided in the bushing compared to the conventional method, or to change the design to reduce the strength of the bushing by increasing the opening area per nozzle hole, and it is possible to widely respond to various glass fiber manufacturing conditions.

In the above configuration, it is preferable to have a pipe connecting the feeder and the bushing.

In this way, by adjusting the vertical length of the pipe, it is possible to easily change the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder. Therefore, the pressure acting on the bushing from the molten glass can be easily changed. As a result, it is possible to avoid placing excessive load on the bushing while ensuring a head pressure appropriate for the flat nozzle hole to allow the molten glass to easily flow out of the nozzle hole.

The present invention, which aims to solve the above problems, is a method for producing glass fibers, which uses a feeder for circulating molten glass and a bushing with a flat nozzle hole disposed below the feeder, and produces irregular cross-section glass fibers by causing the molten glass supplied from the feeder to the bushing to flow out of the nozzle hole while the entire flow path from the feeder to the nozzle hole of the bushing is filled with molten glass, and the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder is set to 0.3 m to 1.5 m.

This method makes it possible to obtain the same effects and advantages as those obtained by the above-mentioned glass fiber manufacturing apparatus.

According to the present invention, when manufacturing irregular cross-section glass fibers, it is possible to easily allow molten glass to flow out of the nozzle hole and to avoid placing excessive load on the bushing.

1 is a cross-sectional view showing a glass fiber manufacturing apparatus and a manufacturing method according to a first embodiment. FIG. 2 is a cross-sectional view showing the periphery of a nozzle for modified cross-section glass fibers provided in the glass fiber manufacturing apparatus according to the first embodiment. FIG. 2 is a bottom view showing the periphery of a nozzle for modified cross section glass fibers provided in the glass fiber manufacturing apparatus according to the first embodiment. FIG. 1 is a diagram showing a nozzle for modified cross-section glass fiber provided in a glass fiber manufacturing apparatus according to a first embodiment, in which (a) is a side view of the nozzle, (b) is a cross-sectional view taken along 4b-4b of (a), (c) is a cross-sectional view taken along 4c-4c of (a), and (d) is a cross-sectional view taken along 4d-4d of (a). FIG. 2 is a cross-sectional view showing a modified cross-section glass fiber. 1A and 1B are diagrams showing a nozzle for modified cross-section glass fiber provided in a glass fiber manufacturing apparatus according to a second embodiment, in which (a) is a side view of the nozzle, (b) is a cross-sectional view taken along line 9b-9b of (a), and (c) is a cross-sectional view taken along line 9c-9c of (a). 11A and 11B are diagrams showing a nozzle for modified cross section glass fibers provided in a glass fiber manufacturing apparatus according to a third embodiment, in which (a) is a side view of the nozzle and (b) is a plan view. FIG. 11 is a cross-sectional view showing a glass fiber manufacturing apparatus and a manufacturing method according to a fourth embodiment. FIG. 13 is a bottom view showing a schematic view of the periphery of a nozzle for modified cross section glass fibers provided in a glass fiber manufacturing apparatus according to a fifth embodiment.

The glass fiber manufacturing apparatus and manufacturing method according to an embodiment of the present invention will be described below with reference to the attached drawings.

First Embodiment
To carry out the glass fiber manufacturing method according to the first embodiment, a glass fiber manufacturing apparatus 1 (hereinafter referred to as manufacturing apparatus 1) as shown in Fig. 1 is used. The manufacturing apparatus 1 includes a feeder 3 for circulating molten glass 2, a bushing 4 arranged below the feeder 3, and a pipe 5 for connecting the feeder 3 and the bushing 4. The manufacturing apparatus 1 is configured to supply molten glass 2 from the feeder 3 to the bushing 4 via the pipe 5, and to produce modified cross-section glass fiber 2f (hereinafter referred to as glass fiber 2f) by drawing out and cooling the molten glass 2 that has flowed out of a nozzle hole 6 of the bushing 4.

In this embodiment, the molten glass 2 is made of E glass. However, this is not limited, and the molten glass 2 may be made of other glasses such as D glass, S glass, AR glass, and C glass.

The feeder 3 is connected to a glass melting furnace (not shown), and is capable of circulating the molten glass 2 produced by continuously melting glass raw materials in the melting furnace. A liquid level 2a of the molten glass 2 is formed inside the feeder 3. The height of the liquid level 2a of the molten glass 2 is adjusted by the amount of glass raw materials supplied to the melting furnace per unit time, etc.

The bushing 4 has a base plate 7 at its bottom. The base plate 7 has a number of nozzles 8 for irregular cross-section glass fibers (hereinafter referred to as nozzles 8) that have the same configuration, and cooling pipes 9 arranged in the vicinity of these nozzles 8. Each nozzle 8 has one nozzle hole 6 formed therein. Details will be described later, but the nozzle hole 6 provided in each nozzle 8 is formed flat.

The pipe 5 has a cylindrical cross-sectional shape and is arranged so that its axis extends in the vertical direction. The upper end of the pipe 5 is connected to the bottom of the feeder 3, and the lower end of the pipe 5 is connected to the upper end of the bushing 4. Note that the cross-sectional shape of the pipe 5 and the direction in which its axis extends may be different from that of this embodiment, as long as the pipe 5 can connect the feeder 3, which is located relatively higher, and the bushing 4, which is located relatively lower. The feeder 3 and the pipe 5 may also be connected by a flow block or bushing block (not shown).

The bushing 4, pipe 5, nozzle 8 and cooling tube 9 are made in part or in whole of platinum or a platinum alloy (e.g., a platinum-rhodium alloy).

The entire flow path from the connection between the bottom of the feeder 3 and the upper end of the pipe 5 to the nozzle hole 6 of the bushing 4 is filled with molten glass 2. As a result, the pressure (head pressure) for causing the molten glass 2 to flow out of the nozzle hole 6 is determined by the height difference H between the nozzle hole 6 and the liquid surface 2a of the molten glass 2 in the feeder 3. Here, the height difference H can be adjusted, for example, mainly by changing the length of the pipe 5.

The height difference H is adjusted to 0.3 m to 1.5 m. This is because if the height difference H is less than 0.3 m, the head pressure will be too small, which may make it difficult to cause the molten glass 2 to flow out of the flat nozzle hole 6. On the other hand, if the height difference H is more than 1.5 m, the head pressure will be too high, which will place an excessive load on the bushing 4 (base plate 7). Preferably, the height difference H is adjusted to 0.5 m to 1.2 m, and more preferably, the height difference H is adjusted to 0.5 m to 1 m.

The temperature and viscosity of the molten glass 2 when forming the glass fiber 2f are set to 1100°C to 1250°C (preferably 1150°C to 1200°C) and 10 ^2.6 dPa·s to 10 ^3.8 dPa·s (preferably 10 ^2.9 dPa·s to 10 ^3.3 dPa·s), respectively. The "temperature and viscosity of the molten glass 2" referred to here means the temperature and viscosity of the molten glass 2 at the position where the molten glass flows into the nozzle 8. The temperature and viscosity of the molten glass 2 are adjusted, for example, by heating both the bushing 4 and the pipe 5. In addition, the temperature and viscosity of the molten glass 2 may be adjusted by heating the molten glass 2 and the feeder 3 in the glass melting furnace by electrical heating or the like.

A bundling agent is applied to the surface of the glass fiber 2f by an applicator (not shown), and several hundred to several thousand glass fibers 2f are spun into a single strand 2s. The spun strand 2s is wound as a fiber bundle 2r around a bobbin 10, which is a winding device. The strand 2s is cut to a length of, for example, about 1 mm to 20 mm, and used as a chopped strand.

As shown in Figures 2 and 3, the nozzle 8 has a pair of relatively long walls 11 and a pair of relatively short walls 12 at the tip from which the molten glass 2 flows. A flat nozzle hole 6 is formed by being surrounded by these walls 11, 12. A notch 13 is provided in each of the pair of long walls 11, 11, and the nozzle hole 6 is connected to the external space of the nozzle 8 through the notch 13.

The cooling pipe 9 cools the molten glass 2 by circulating cooling water 14 inside the cooling pipe 9. The cooling pipe 9 has a plate-like outer shape and is arranged so that the plate surface is parallel to the long wall portion 11. Here, the cooling pipe 9 is provided integrally with the base plate 7, but it may be provided at a position away from the base plate 7. The cooling pipe 9 may also be formed in a circular pipe shape.

The height position of the cooling pipe 9 is adjusted according to the cooling conditions of the molten glass 2. As an example, the cooling pipe 9 may be arranged above the tip of the nozzle 8 so that the molten glass 2 drawn from the nozzle 8 does not face the plate surface. On the other hand, the cooling pipe 9 may be arranged above and below the tip of the nozzle 8 so that both the nozzle 8 and the molten glass 2 drawn from the nozzle 8 face the plate surface. In addition to the cooling pipe 9, cooling fins that cool the molten glass 2 by air flow may be used to cool the molten glass 2. The cooling pipe 9 is not an essential component and may be omitted.

As shown in FIG. 3, multiple nozzle rows P are arranged in parallel with a gap between them on the base plate 7. Each nozzle row P includes multiple nozzles 8. The multiple nozzles 8 included in the same nozzle row P are arranged so that the nozzle holes 6 formed therein are positioned on the same straight line. The number of nozzle holes 6 is, for example, 100 or more, preferably 300 or more, and more preferably 800 or more. The number of nozzle holes 6 is 5,000 or less, preferably 3,000 or less, and more preferably 1,500 or less.

The cooling pipe 9 is arranged between the adjacent nozzle rows P, P so as to extend parallel to the nozzle row P. This allows the molten glass 2 in the nozzle hole 6 to be cooled through the notch 13 facing the cooling pipe 9. Specifically, at the tip of the nozzle 8, the molten glass 2 is rapidly cooled from a temperature of 1000°C or higher by the cooling pipe 9. Here, the cooling pipe 9 also functions to cool the bushing 4 (base plate 7) and the nozzle 8, thereby suppressing thermal deterioration of these components and increasing their durability.

As shown in Figures 4(a) to (d), the notch 13 provided in each long wall 11 of each nozzle 8 is formed in an isosceles trapezoid shape with an upper base shorter than the lower base. As a result, the opening width of the notch 13 gradually increases as it moves toward the tip of the nozzle 8. In this embodiment, the lower base of the trapezoid is approximately the same length as the long wall 11. The depth D (length along the vertical direction) of the notch 13 is set to 0.1 mm to 2 mm. This is because if the depth D exceeds 2 mm, both ends in the longitudinal direction of the cross section of the manufactured glass fiber 2f become too thin, making the glass fiber 2f more likely to break.

The shape of the notch 13 is not limited to a trapezoidal shape, and may be other shapes. For example, it may be triangular or semicircular. However, even when these other shapes are adopted, it is preferable that the opening width of the notch 13 gradually increases as it moves toward the tip of the nozzle 8. Also, the notch 13 is not an essential component and may be omitted.

The nozzle hole 6 has an inlet for the molten glass 2 formed at the base end of the nozzle 8 and an outlet for the molten glass 2 formed at the tip end, and the cross section of the nozzle hole 6 has a uniform shape from the inlet to the outlet. Here, each nozzle hole 6 formed in the multiple nozzles 8 has the same configuration (shape, dimensions, surface roughness of the inner circumferential surface 15). The cross-sectional shape of the nozzle hole 6 may be different between the inlet and the outlet. In other words, the shape of the nozzle hole 6 may change from the inlet to the outlet.

The nozzle hole 6 has an inner peripheral surface 15 made of platinum or a platinum alloy. The inner peripheral surface 15 has a pair of short wall surfaces 15a, 15a that face each other in the long diameter direction of the nozzle hole 6, and a pair of long wall surfaces 15b, 15b that face each other in the short diameter direction. In this embodiment, the pair of short wall surfaces 15a, 15a are arc-shaped, and the pair of long wall surfaces 15b, 15b are parallel. Therefore, the nozzle hole 6 has an elliptical shape. Here, when the length of the short wall surface 15a along the short diameter direction is X and the length of the long wall surface 15b along the long diameter direction is Y, the value of (Y/X) is set to 2 to 5. In addition, when the cross-sectional shape of the nozzle hole 6 changes from the inlet to the outlet, the value of (Y/X) is set to be within the range of 2 to 5 before and after the change. In this case, the value of (Y/X) may be different before and after the change.

The average value of the surface roughness Ra on the short wall surface 15a is greater than the average value of the surface roughness Ra on the long wall surface 15b. Specifically, the average value of the surface roughness Ra on the short wall surface 15a is in the range of 2 μm or more and 10 μm or less, and the average value of the surface roughness Ra on the long wall surface 15b is in the range of 1 μm or more and less than 10 μm.

The average surface roughness Ra can be adjusted by changing the shape of the drill used to form the nozzle hole 6 by drilling or by vibrating the drill. It can also be adjusted by contacting the nozzle hole 6 with the drill again after it has been formed or by annealing it.

Here, the average value of the surface roughness Ra is the value in an unused state (before the molten glass 2 is circulated). Specific measurement modes of the average value of the surface roughness Ra are as follows (1) to (4). (1) After producing a plurality of nozzles 8 that can be incorporated into this manufacturing apparatus under the same manufacturing conditions, the nozzle 8 to be measured is extracted as a sample from among them. (2) The extracted sample is cut along the direction in which the hole axis of the nozzle hole 6 extends (the direction that becomes the up-down direction in Figures 1 and 2 when incorporated into this manufacturing apparatus). (3) The inner surface 15 (short wall surface 15a and long wall surface 15b) of the nozzle hole 6 is measured along the direction in which the hole axis extends in accordance with JIS B 0601:2001. Note that the measurement is performed using a Surfcorder (product name: ET4000) manufactured by Kosaka Laboratory Co., Ltd., and the measurement distance is 1 mm. Here, measurements are performed at six different locations (three locations on each of the short wall surface 15a and the long wall surface 15b). (4) The surface roughness Ra values measured at each of the six locations are averaged to obtain the average surface roughness Ra of the inner circumferential surface 15. Furthermore, the three surface roughness Ra values measured on each of the short wall surface 15a and the long wall surface 15b are averaged to obtain the average surface roughness Ra of the short wall surface 15a and the long wall surface 15b. The average surface roughness Ra of the inner circumferential surface 15, the short wall surface 15a, and the long wall surface 15b of the nozzle 8 other than the sample is then considered to be the same value as the average surface roughness Ra measured for the sample.

The average value of the kurtosis Rku (kurtosis) on the inner peripheral surface 15 of the nozzle hole 6 is 2 or more (preferably in the range of 4 to 10). The magnitude relationship of the kurtosis Rku between the short wall surface 15a and the long wall surface 15b is the same as the surface roughness Ra.

Each of the glass fibers 2f produced by the present manufacturing apparatus configured as described above is an irregular cross-section glass fiber having a flat cross-sectional shape (shape in a cross section perpendicular to the drawing direction) as shown in FIG. 5. With this manufacturing apparatus, the contact resistance between the molten glass 2 on the short wall surface 15a and the inner peripheral surface 15 is greater than the contact resistance between the molten glass 2 on the long wall surface 15b and the inner peripheral surface 15. Therefore, it is possible to prevent the entire cross section of the glass fiber 2f from curling, and it is possible to produce a fiber with a high flatness ratio.

Therefore, according to the manufacturing device 1 configured as described above, the height difference H can be made 1.5 m or less, and excessive load on the bushing 4 (base plate 7) can be avoided. Furthermore, according to the manufacturing device 1 configured as described above, the height difference H is 0.3 m or more, so that the molten glass 2 can easily flow out of the nozzle hole 6. Therefore, while avoiding damage to the bushing 4 (base plate 7) due to high pressure, glass fibers 2f having a cross-sectional shape with a high flattening ratio (cross-sectional shape perpendicular to the drawing direction of the glass fibers 2f) as shown in FIG. 5 can be obtained. Specifically, the cross-sectional shape of the glass fibers 2f is formed into a shape close to an ellipse.

Other embodiments will be described below. In the description of the other embodiments, elements that are substantially the same as those already described in the first embodiment will be given the same reference numerals to omit redundant description, and only the differences from the first embodiment will be described.

Second Embodiment
As shown in Fig. 6(a) to (c), the second embodiment is different from the first embodiment in that, when viewed from the direction along the axis of the nozzle hole 6, the pair of short wall surfaces 15a are linear and parallel to each other, and the distance between the pair of long wall surfaces 15b decreases toward the center of the nozzle hole 6. As a result, the cross-sectional area of both ends of the nozzle hole 6 is larger than that of the center. As a result, the amount of molten glass 2 flowing out from the center of the nozzle hole 6 is smaller than the amount of molten glass 2 flowing out from both ends of the nozzle hole 6, so that the molten glass 2 in the center is quickly cooled and solidified, and as a result, the molten glass 2 is less likely to deform in a direction that reduces its surface area. Therefore, it is possible to manufacture a high flatness fiber. In addition, by adjusting the distance between the pair of long wall surfaces 15b at the center and both ends, the height difference H can be set according to the distance.

It is preferable that the surface roughness Ra of the short wall surface 15a and the long wall surface 15b be the same as in the first embodiment.

Third Embodiment
As shown in Figures 7(a) and 7(b), the third embodiment differs from the first embodiment in that the nozzle hole 6 is formed in a dumbbell shape. In this embodiment, as shown in Figure 7, the nozzle 8 includes a pair of central wall surfaces 15c, 15c constituting a wall surface on the central side of the nozzle hole 6, and a pair of end wall surfaces 15d, 15d constituting wall surfaces on both ends of the nozzle hole 6. The end wall surfaces 15d include a pair of vertical end wall surfaces 15d1, 15d1 that are continuous with the central wall surface 15c and perpendicular to the central wall surface 15c in a plan view, a pair of parallel end wall surfaces 15d2, 15d2 that are continuous with the vertical end wall surface 15d1 and parallel to the central wall surface 15c in a plan view, and end wall surfaces 15d3 that are continuous with the pair of parallel end wall surfaces 15d2 and parallel to the vertical end wall surfaces 15d1. As a result, the molten glass 2 flowing out from both end wall surfaces 15d is surrounded by both vertical end wall surfaces 15d1, both parallel end wall surfaces 15d2, and both end wall surfaces 15d3, so that the molten glass 2 receives a large resistance force from both end wall surfaces 15d. As a result, curling of the entire cross section of the glass fiber 2f can be prevented, and it is possible to produce a fiber with a high flatness. The height difference H can be adjusted by adjusting the shape of both end wall surfaces 15d.

As in the first embodiment, it is preferable that the average value of the surface roughness Ra at both end wall surfaces 15d is greater than the average value of the surface roughness Ra at the central wall surface 15c.

<Fourth embodiment>
In the fourth embodiment shown in Fig. 8, the manufacturing apparatus 1 includes a heating means 18 for creating a temperature difference between the bushing 4 and the pipe 5, and the heating means 18 adjusts the temperature of the pipe 5 to a higher temperature than the temperature of the bushing 4. This allows the temperature of the molten glass 2 before it flows into the bushing 4 to be maintained higher than the temperature of the molten glass 2 when it flows out of the nozzle hole 6 (a temperature suitable for forming the glass fiber 2f). The temperature of the molten glass 2 before it flows into the bushing 4 and the temperature of the molten glass 2 when it flows out of the nozzle hole 6 are adjusted as described below, so that the height difference H can be set according to the temperature.

The heating means 18 includes a first heater 19 that electrically heats the bushing 4, and a second heater 20 that electrically heats the pipe 5. The first heater 19 and the second heater 20 can independently adjust the magnitude of the current flowing through the bushing 4 and the pipe 5, making it possible to heat the bushing 4 and the pipe 5 separately. Note that instead of the second heater 20, a heater equipped with a coil for induction heating that surrounds the pipe 5 may be disposed.

In this device, the temperature of the pipe 5 can be adjusted to a higher temperature than the temperature of the bushing 4, so that the temperature of the molten glass 2 can be kept high until just before it flows from the pipe 5 into the bushing 4, and the viscosity can be kept low upstream of the bushing 4. Furthermore, it is possible to lower the temperature of the molten glass 2 after it flows into the bushing 4, and to increase its viscosity to a level suitable for producing fibers with a high flattening ratio. In this way, the pressure loss when the molten glass 2 flows through the pipe 5 can be reduced to the extent that the viscosity of the molten glass 2 can be reduced until just before it flows into the bushing 4. Therefore, the height difference between the nozzle hole 6 and the liquid surface of the molten glass 2 in the feeder 3 can be reduced.

Here, the temperature of the bushing 4 is preferably 1100°C or higher to avoid devitrification of the molten glass 2. The temperature of the bushing 4 is, for example, 1130°C to 1280°C. Meanwhile, the temperature of the pipe 5 is, for example, 1180°C to 1350°C. In this embodiment, the temperature difference between the bushing 4 and the pipe 5 is set to 50°C to 200°C.

Fifth Embodiment
9 (excluding components other than nozzle hole 6 and base plate 7), nozzle hole 6 is formed in an elliptical shape, and the ratio of the opening area of nozzle hole 6 to a unit area of base plate 7 is adjusted to 5% to 15%. The reason for adjusting the ratio within this range is that if the ratio is less than 5%, it may be difficult to cause molten glass 2 to flow out from nozzle hole 6, and if the ratio exceeds 15%, the strength of bushing 4 (base plate 7) may be insufficient.

In this embodiment, the above ratio is calculated by {(sum of areas of hatched regions in FIG. 9)/(S1×S2)}×100. The above ratio may be adjusted by increasing or decreasing the number of nozzle holes 6 while fixing the opening area of each nozzle hole 6, or by increasing or decreasing the opening area of each nozzle hole 6 while fixing the number of nozzle holes 6. However, the opening area of each nozzle hole 6 is preferably 3 mm ² to 15 mm ^2. The value of (Y/X) for the nozzle holes 6 is preferably 2 to 8.

The glass fiber manufacturing apparatus and manufacturing method according to the present invention are not limited to the configurations and aspects described in the above embodiment. For example, in the above embodiment, the bottom of the feeder 3 and the upper end of the bushing 4 are connected by a pipe 5, but this is not limited to the above. The pipe 5 may be removed and the upper end of the bushing 4 may be directly attached to the bottom of the feeder 3. Even in this case, the height difference H between the nozzle hole 6 and the liquid surface 2a of the molten glass 2 in the feeder 3 is set to 0.3 m to 1.5 m.

Reference Signs List 1: Glass fiber manufacturing device 2: Molten glass 2a: Liquid surface 2f: Deformed cross-section glass fiber 3: Feeder 4: Bushing 5: Pipe 6: Nozzle hole H: Height difference

Claims (3)

a feeder for flowing molten glass, a bushing having a flat nozzle hole and disposed below the feeder , a pipe connecting the feeder and the bushing, and a heating means for providing a temperature difference between the bushing and the pipe ,
A glass fiber manufacturing apparatus for manufacturing a modified cross section glass fiber by causing molten glass supplied from the feeder to the bushing to flow out of the nozzle hole in a state where an entire flow path from inside the feeder to the nozzle hole of the bushing is filled with molten glass,
The temperature of the pipe is adjusted by the heating means to be higher than the temperature of the bushing, and the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder is set to 0.3 m to 1.5 m. 2. The glass fiber manufacturing apparatus according to claim 1 , wherein the temperature difference between the bushing and the pipe is 50°C to 200°C. A method for producing a molten glass by using a feeder for flowing molten glass, a bushing having a flat nozzle hole and disposed below the feeder , a pipe connecting the feeder and the bushing, and a heating means for providing a temperature difference between the bushing and the pipe ,
A method for producing a modified cross section glass fiber, comprising the steps of: filling an entire flow path from the inside of the feeder to the nozzle hole of the bushing with molten glass; and causing molten glass supplied from the feeder to the bushing to flow out of the nozzle hole to produce a modified cross section glass fiber,
A method for manufacturing glass fibers , wherein the temperature of the pipe is adjusted by the heating means to be higher than the temperature of the bushing, and the height difference between the nozzle hole and the liquid surface of the molten glass in the feeder is set to 0.3 m to 1.5 m.