Bushing device and glass fiber production method

Abstract

A bushing device (12) used for the production of glass fibers comprises a bushing (13). The bushing (13) has a nozzle group (14) through which molten glass flows out, and a bushing plate (15) on which the nozzle group (14) is provided. The bushing device (12) is provided with a terminal (19) for heating the bushing plate (15) by energization. The bushing plate (15) has a plate body part (20) in which the nozzle group (14) is disposed, and a thin-walled part (21) having a smaller thickness than the plate body part (20).

Description

Bushing device and method for manufacturing glass fiber

[0001] The present invention relates to a bushing device and a method for manufacturing glass fiber.

[0002] As described in Patent Document 1, for the production of glass fiber, a bushing through which molten glass flows out is used. The bushing includes a bushing plate provided with a nozzle group. During the production of glass fiber, the bushing plate of the bushing may be electrically heated to adjust the temperature of the molten glass in the bushing.

[0003] Japanese Unexamined Patent Application Publication No. 2017-024967

[0004] The temperature of the bushing plate of the bushing for manufacturing glass fiber as described above may partially decrease due to the influence of the ambient environment such as the airflow flowing around the bushing. Such partial temperature decrease of the bushing plate may cause unstable outflow of the molten glass from the nozzle group. To stably discharge the molten glass from the nozzle group, it is important to improve the temperature uniformity of the bushing plate.

[0005] An object of the present invention is to provide a bushing device and a method for manufacturing glass fiber that enable improvement of the temperature uniformity of the bushing plate.

[0006] Each aspect of the bushing device and the method for manufacturing glass fiber that solve the above problems will be described. The bushing device according to Aspect 1 includes a bushing having a nozzle group for discharging molten glass and a bushing plate provided with the nozzle group, and is a bushing device used for manufacturing glass fiber. The bushing device includes a terminal for electrically heating the bushing plate, and the bushing plate has a plate main body portion where the nozzle group is arranged and a thin portion having a smaller thickness dimension than the plate main body portion.

[0007] This configuration makes it possible to increase the current density in the thin-walled portion of the bushing plate compared to the main body of the bushing plate. This allows for faster heat generation in the thin-walled portion of the bushing plate compared to the main body. By utilizing this heat generation in the thin-walled portion, it is possible to suppress localized temperature drops in the bushing plate.

[0008] In the bushing device of embodiment 2, the thin-walled portion may be provided so as to extend from the outer peripheral edge of the bushing plate in embodiment 1. The outer peripheral edge of the bushing plate is prone to temperature drops due to, for example, the influence of airflow from outside the bushing plate. Therefore, by providing the thin-walled portion as described above, the portion of the bushing plate that is prone to temperature drops can be preferentially heated.

[0009] In the bushing device of embodiment 3, in embodiment 1 or embodiment 2, the plate body portion includes a first plate body portion on which a first nozzle group is arranged and a second plate body portion on which a second nozzle group adjacent to the first nozzle group is arranged, and the thin-walled portion may be provided between the first plate body portion and the second plate body portion.

[0010] In the bushing plate, airflow easily flows in from the outside of the bushing plate between the first nozzle group and the second nozzle group. Therefore, the temperature of the portion of the bushing plate between the first plate body and the second plate body tends to be lower than the temperature of the plate body. For this reason, by providing a thin-walled portion as described above, the portion of the bushing plate that tends to lose temperature can be preferentially heated.

[0011] In the bushing device of embodiment 4, in any one of embodiments 1 to 3, the terminal includes a first terminal and a second terminal arranged opposite to the first terminal, and the thin-walled portion may be provided so as to divide the space between the first terminal and the second terminal in a plan view of the bushing plate. With this configuration, for example, it is possible to efficiently promote the heating of the thin-walled portion by utilizing the current flow between the first terminal and the second terminal.

[0012] In the bushing device of embodiment 5, in any one of embodiments 1 to 4, if the thickness dimension of the plate body is T1 and the thickness dimension of the thin-walled portion is T2, then T1 and T2 may satisfy the relationship represented by the following formula (1).

[0013] 0.75 × T1 ≤ T2 ≤ 0.95 × T1 ... (1) This configuration promotes heat generation in the thin-walled section and suppresses the reduction in strength of the bushing plate due to the thin-walled section.

[0014] In the bushing device of embodiment 6, in any one of embodiments 1 to 5, the thin-walled portion has a longitudinal direction, and the thickness dimensions of both ends of the thin-walled portion in the longitudinal direction may be smaller than the thickness dimension of the intermediate portion between the two ends. This configuration allows for better heat generation at both ends of the thin-walled portion in the longitudinal direction than at the intermediate portion. For this reason, for example, when using the bushing device in an environment where the temperature of both ends of the thin-walled portion of the bushing plate tends to drop more easily than at the intermediate portion, it is advantageous in terms of improving the uniformity of the temperature of the bushing plate. Furthermore, by having a thickness dimension of the intermediate portion of the thin-walled portion that is larger than the thickness dimensions of both ends of the thin-walled portion, it is possible to suppress a decrease in the strength of the bushing plate.

[0015] In the bushing device of embodiment 7, in any one of embodiments 1 to 6, the thin-walled portion may be composed of a groove that opens below the bushing plate. This configuration makes it possible to avoid, for example, the formation of irregularities on the upper surface of the bushing plate, which is the inner surface of the bushing, due to the thin-walled portion, or to reduce the irregularities formed on the upper surface of the bushing plate. As a result, for example, it becomes possible to smoothly flow molten glass along the upper surface of the bushing plate.

[0016] In the bushing device of embodiment 8, in any one of embodiments 1 to 7, the bushing plate may be constructed as an integral structure without a welded joint. In this case, it is possible to suppress the occurrence of unintended uneven heating when the bushing plate is heated by electric current.

[0017] The glass fiber manufacturing method of embodiment 9 comprises a molding step of forming glass fibers using the bushing device described above, wherein the bushing plate is heated by applying an electric current during the molding step.

[0018] This invention has the effect of improving the uniformity of the temperature of the bushing plate.

[0019] Figure 1 is a front view showing a glass fiber manufacturing apparatus in an embodiment. Figure 2 is a bottom view showing a bushing device. Figure 3 is a cross-sectional view along line 3-3 in Figure 2. Figure 4 is a cross-sectional view showing a first modified example of the bushing device. Figure 5 is a cross-sectional view showing a second modified example of the bushing device. Figure 6 is a bottom view showing a third modified example of the bushing device.

[0020] An embodiment of a method for manufacturing a bushing and glass fiber will be described below with reference to the drawings. Note that, for the sake of clarity, some parts of the structure may be exaggerated or simplified in the drawings. Also, the dimensional ratios of each part may differ from those of the actual structure.

[0021] <Overview of the Glass Fiber Manufacturing Apparatus> As shown in Figure 1, the glass fiber manufacturing apparatus 11 is equipped with a bushing apparatus 12. The bushing apparatus 12 is equipped with a bushing 13. The bushing 13 has a group of nozzles 14 for discharging molten glass MG and a bushing plate 15 on which the group of nozzles 14 is provided. The group of nozzles 14 of the bushing 13 forms glass filaments GF.

[0022] The glass fiber manufacturing apparatus 11 includes an applicator 16 for applying a liquid sizing agent to glass filaments GF, and a gathering shoe 17 for gathering multiple glass filaments GF coated with the sizing agent. By gathering multiple glass filaments GF with the gathering shoe 17, a glass strand GS is obtained. Although not shown in the figures, the glass fiber manufacturing apparatus 11 also includes a traverse for moving the glass strand GS back and forth, and a collet for winding up the glass strand GS that has passed through the traverse.

[0023] Examples of molten glass MG include E glass (alkaline content of 2% or less), D glass (low dielectric constant glass), AR glass (alkali-resistant glass), C glass (acid-resistant glass), M glass (high modulus glass), S glass (high strength, high modulus glass), T glass (high strength, high modulus glass), H glass (high dielectric constant glass), and NE glass (low dielectric constant glass). The density of the glass is, for example, 2.0 to 3.0 g / cm³. ３ That is the case.

[0024] In the following diagrams, the X-axis represents the horizontal direction, the Y-axis represents the horizontal direction perpendicular to the X-axis, and the Z-axis represents the vertical direction perpendicular to the XY plane. The molten glass MG flows down along the Z-axis. The bushing plate 15 is positioned so that its main surface is aligned with the horizontal direction.

[0025] <Bushing Device> As shown in Figures 1 to 3, the bushing 13 of the bushing device 12 is equipped with a bushing body 18 to which molten glass MG is supplied. The bushing plate 15 of the bushing 13 is provided at the bottom of the bushing body 18. Molten glass MG is supplied to the bushing body 18 from a supply port (not shown). The bushing body 18 may be equipped with a screen to suppress the accumulation of foreign matter on the bushing plate 15.

[0026] The bushing device 12 is equipped with a terminal 19 for electrically heating the bushing plate 15. The terminal 19 is connected to a power supply (not shown). By supplying power from the power supply to the terminal 19, the bushing plate 15 can be electrically heated.

[0027] Terminal 19 includes a first terminal 19a and a second terminal 19b positioned opposite the first terminal 19a. In this embodiment, the first terminal 19a is connected to the side wall of the bushing body 18, but may also be connected to the bushing plate 15. In this embodiment, the second terminal 19b is connected to the side wall of the bushing body 18, but may also be connected to the bushing plate 15.

[0028] The planar shape of the bushing plate 15 is, for example, a rectangle. In this embodiment, the planar shape of the bushing plate 15 is rectangular, having a pair of long sides extending along the X-axis and a pair of short sides extending along the Y-axis. The planar shape of the bushing plate 15 may also be, for example, a square.

[0029] The bushing plate 15 has a plate body portion 20 on which the nozzle group 14 is arranged, and a thin-walled portion 21 which is thinner than the plate body portion 20. The plate body portion 20 of the bushing plate 15 has multiple through holes for attaching the multiple nozzles. The plate body portion 20 is the area surrounding the through holes located on the outermost periphery among the multiple through holes for attaching the nozzle group 14. In other words, the plate body portion 20 of the bushing plate 15 refers to the area enclosed by the dashed line in the plan view of the bushing plate 15 shown in Figure 2.

[0030] The nozzle group 14 of this embodiment includes a first nozzle group 14a and a second nozzle group 14b adjacent to the first nozzle group 14a. The plate body portion 20 of this embodiment has a first plate body portion 20a on which the first nozzle group 14a is arranged and a second plate body portion 20b on which the second nozzle group 14b is arranged. The distance between the first plate body portion 20a and the second plate body portion 20b is wider than the distance between adjacent through holes in the plate body portion 20. The first plate body portion 20a and the second plate body portion 20b are arranged along the longitudinal direction of the bushing plate 15.

[0031] Molten glass MG is supplied to each of the multiple first nozzles N1 of the first nozzle group 14a and the multiple second nozzles N2 of the second nozzle group 14b, thereby drawing out glass filaments GF from each nozzle. More specifically, the first glass filament group GF1 is drawn out from the first nozzle group 14a. The first glass filament group GF1 is bundled to obtain the first glass strand GS1. The second glass filament group GF2 is drawn out from the second nozzle group 14b. The second glass filament group GF2 is bundled to obtain the second glass strand GS2.

[0032] In the drawings, the plurality of first nozzles N1 of the first nozzle group 14a and the plurality of second nozzles N2 of the second nozzle group 14b are shown in a simplified manner. The number of nozzles in each of the plurality of first nozzles N1 and the plurality of second nozzles N2 is preferably 800 to 10,000, and more preferably 2,000 to 8,000.

[0033] The thin-walled portion 21 of the bushing plate 15 is provided so as to extend from the outer peripheral edge of the bushing plate 15. More specifically, the thin-walled portion 21 is provided so as to extend from the first edge portion E1 and the second edge portion E2 of the bushing plate 15 that are opposite each other. The thin-walled portion 21 is provided between the first plate body portion 20a and the second plate body portion 20b.

[0034] The thin-walled portion 21 is provided to divide the bushing plate 15 between the first terminal 19a and the second terminal 19b in a plan view. The first terminal 19a is connected to the first plate body portion 20a side of the bushing 13. The second terminal 19b is connected to the second plate body portion 20b side of the bushing 13. The thin-walled portion 21 of the bushing plate 15 is provided to traverse a pair of long sides in a plan view of the bushing plate 15.

[0035] As shown in Figures 2 and 3, the thin-walled portion 21 of this embodiment has a longitudinal direction extending along a pair of short sides in a plan view of the bushing plate 15. The shape of the thin-walled portion 21 can be, for example, straight, curved, or bent in a plan view of the bushing plate 15. The shape of the thin-walled portion 21 may be a combination of different shapes, such as a straight line and a curved line. The thin-walled portion 21 of this embodiment is composed of a groove that opens to the bottom of the bushing plate 15. The upper surface of the bushing plate 15, including the upper surface of the thin-walled portion 21, is preferably a flat surface.

[0036] When the thickness dimension of the main body of the plate 20 is T1 and the thickness dimension of the thin-walled portion 21 is T2, it is preferable that T1 and T2 satisfy the relationship expressed by the following formula (1): 0.75 × T1 ≤ T2 ≤ 0.95 × T1 ... (1) As the thickness dimension T2 of the thin-walled portion 21 decreases, it becomes possible to further promote heat generation by the thin-walled portion 21. As the thickness dimension T2 of the thin-walled portion 21 increases, it becomes possible to suppress the reduction in strength of the bushing plate 15 due to the thin-walled portion 21.

[0037] The thickness dimension of the plate body portion 20 is preferably constant. If the thickness dimension of the plate body portion 20 is not constant, the thickness dimension T1 of the plate body portion 20 in formula (1) above is the minimum thickness dimension of the plate body portion 20. The thickness dimension of the plate body portion 20 is preferably, for example, within the range of 1 mm or more and 5 mm or less.

[0038] In this embodiment, the thickness dimension of the thin-walled portion 21 is constant, but the thickness dimension of the thin-walled portion 21 does not have to be constant. If the thickness dimension of the thin-walled portion 21 is not constant, the thickness dimension T2 in the above formula (1) is the maximum thickness dimension of the thin-walled portion 21.

[0039] The bushing plate 15 has an outer peripheral portion 22 adjacent to the outer circumference of the plate body portion 20. The outer peripheral portion 22 reinforces the plate body portion 20, for example. The bushing plate 15 of this embodiment includes a first outer peripheral portion 22a adjacent to the outer circumference of the first plate body portion 20a and a second outer peripheral portion 22b adjacent to the outer circumference of the second plate body portion 20b. The thin-walled portion 21 of this embodiment is adjacent to the first outer peripheral portion 22a and the second outer peripheral portion 22b. The first outer peripheral portion 22a has a portion that is positioned between the thin-walled portion 21 and the first plate body portion 20a. The second outer peripheral portion 22b has a portion that is positioned between the thin-walled portion 21 and the second plate body portion 20b.

[0040] The first outer periphery 22a has the same thickness dimension as the first plate body 20a. The thickness dimension of the first outer periphery 22a may be greater than the thickness dimension of the first plate body 20a. The shape of the first outer periphery 22a in this embodiment is a continuous frame shape, but it may also be a frame shape with a part cut out.

[0041] The second outer periphery 22b has the same thickness dimension as the second plate body 20b. The thickness dimension of the second outer periphery 22b may be greater than the thickness dimension of the second plate body 20b. In this embodiment, the shape of the second outer periphery 22b is a continuous frame shape, but it may also be a frame shape with a part cut out.

[0042] The bushing plate 15 is obtained by processing a metal plate using a well-known processing method. The thin-walled portion 21 of the bushing plate 15 can be formed, for example, by processing methods such as grinding, pressing, or etching of the metal plate.

[0043] Furthermore, a bushing plate 15 can also be obtained by welding a first metal plate which becomes the first plate body portion 20a, a second metal plate which becomes the second plate body portion 20b, and a third metal plate which becomes the thin-walled portion 21. However, when a bushing plate 15 is obtained by joining multiple metal plates by welding in this way, a welded portion with a raised shape, for example, is formed on the bushing plate 15. Such a bushing plate 15 is prone to minute irregularities caused by the welded portion. Differences in current density between the minute irregularities caused by the welded portion of the bushing plate 15 and the area around these irregularities may cause differences in the amount of heat generated. As a result, unintended uneven heating may occur in the bushing plate 15. In contrast, if the bushing plate 15 is formed by at least one of the above-mentioned metal plate grinding, pressing, and etching methods, minute irregularities caused by the welded portion will not occur, making it possible to suppress the occurrence of unintended uneven heating. In other words, when the bushing plate 15 is constructed as an integral structure without welded joints, it becomes possible to suppress the occurrence of unintended uneven heating when the bushing plate 15 is heated by electric current.

[0044] As materials for each of the bushing body 18, the bushing plate 15, the nozzle group 14, and the terminal 19, for example, noble metals, noble metal alloys, etc. may be mentioned. The noble metal is gold, silver, platinum, palladium, rhodium, iridium, ruthenium, or osmium. Among these materials, from the viewpoint of enhancing durability, it is preferable to be at least one of platinum and platinum alloys. Examples of the platinum alloy include a platinum-rhodium alloy.

[0045] <Method for manufacturing glass fiber> Next, the method for manufacturing glass fiber will be described together with the main operations of the bushing device 12.

[0046] The method for manufacturing glass fiber includes a molding step of molding the glass filament GF using the above-described bushing device 12. In the molding step, a plurality of glass filaments GF are molded by causing the molten glass MG supplied to the bushing 13 to flow out from the nozzle group 14 of the bushing 13. The obtained plurality of glass filaments GF are gathered using the applicator 16 and the gathering shoe 17 to obtain a glass strand GS.

[0047] The glass strand GS can be used, for example, as a chopped strand cut to a predetermined length. Further, the glass strand GS can be used as a milled fiber, roving, yarn, mat, cloth, tape, or woven fabric. Examples of the uses of the glass strand GS include vehicle uses, electronic material uses, building material uses, civil engineering uses, aircraft-related uses, shipbuilding uses, logistics uses, industrial machinery uses, and daily goods uses.

[0048] In the molding step in the method for manufacturing glass fiber, the bushing plate 15 of the bushing 13 is heated by energization. Thereby, the bushing plate 15 and the nozzle group 14 can be heated.

[0049] The bushing plate 15 of the bushing device 12 has the plate body portion 20 and the thin-walled portion 21 described above. With this configuration, it is possible to increase the current density of the thin-walled portion 21 of the bushing plate 15 compared to the plate body portion 20 of the bushing plate 15. This makes it possible to promote the heat generation of the thin-walled portion 21 of the bushing plate 15 more than that of the plate body portion 20. By utilizing the heat generated by this thin-walled portion 21, it is possible to suppress a localized temperature drop of the bushing plate 15.

[0050] Next, an example of utilizing the heat generated by the thin-walled portion 21 of the bushing plate 15 will be described. In the molding process of the glass fiber manufacturing method, for example, an airflow may be generated from the outside of the bushing plate 15 toward the first plate body portion 20a and the second plate body portion 20b. Such an airflow is called an accompanying airflow. The accompanying airflow lowers the temperature of the portion of the bushing plate 15 between the first plate body portion 20a and the second plate body portion 20b. At this time, by utilizing the heat generated by the thin-walled portion 21 of the bushing plate 15, it is possible to suppress the temperature drop of the portion between the first plate body portion 20a and the second plate body portion 20b. As a result, it is possible to suppress the temperature drop of the nozzle adjacent to the portion between the first plate body portion 20a and the second plate body portion 20b. Therefore, it is possible to stably discharge molten glass MG from the nozzle group 14.

[0051] <Operation and Effects of the Embodiment> Next, the operation and effects of the embodiment will be described. (1) The bushing 13 of the bushing device 12 used in the manufacture of glass fibers has a group of nozzles 14 for discharging molten glass MG and a bushing plate 15 on which the group of nozzles 14 is provided. The bushing device 12 is equipped with a terminal 19 for electrically heating the bushing plate 15. The bushing plate 15 of the bushing 13 has a plate body portion 20 on which the group of nozzles 14 is arranged and a thin-walled portion 21 which has a smaller thickness than the plate body portion 20.

[0052] With this configuration, as described above, it is possible to promote the heat generation of the thin-walled portion 21 of the bushing plate 15 more than that of the plate body portion 20. By utilizing the heat generated by this thin-walled portion 21, it is possible to suppress localized temperature drops in the bushing plate 15. Therefore, it is possible to improve the uniformity of the temperature of the bushing plate 15. As a result, it is possible to stably discharge molten glass MG from the nozzle group 14, thereby increasing the productivity of glass fibers.

[0053] (2) The thin-walled portion 21 of the bushing plate 15 is provided so as to extend from the outer edge of the bushing plate 15. The outer edge of the bushing plate 15 is prone to temperature drops due to the influence of airflow from outside the bushing plate 15, for example. Therefore, by providing the thin-walled portion 21 as described above, the parts of the bushing plate 15 that are prone to temperature drops can be preferentially heated. Thus, it is possible to easily improve the uniformity of the temperature of the bushing plate 15.

[0054] (3) The plate body portion 20 of the bushing 13 includes a first plate body portion 20a on which the first nozzle group 14a is arranged, and a second plate body portion 20b on which the second nozzle group 14b adjacent to the first nozzle group 14a is arranged. The thin-walled portion 21 is provided between the first plate body portion 20a and the second plate body portion 20b.

[0055] In the bushing plate 15, airflow easily flows in from the outside of the bushing plate 15 between the first nozzle group 14a and the second nozzle group 14b. Therefore, the temperature of the portion of the bushing plate 15 between the first plate body portion 20a and the second plate body portion 20b tends to be lower than the temperature of the plate body portion 20. By providing the thin-walled portion 21 as described above, the portion of the bushing plate 15 that tends to lose temperature can be preferentially heated. Thus, it is possible to improve the uniformity of the temperature of the bushing plate 15 provided with the first nozzle group 14a and the second nozzle group 14b.

[0056] (4) The terminal 19 of the bushing device 12 includes a first terminal 19a and a second terminal 19b which is positioned opposite the first terminal 19a. The thin-walled portion 21 of the bushing plate 15 is provided to divide the space between the first terminal 19a and the second terminal 19b in a plan view of the bushing plate 15. In this case, for example, it is possible to efficiently promote the heating of the thin-walled portion 21 by utilizing the current flow between the first terminal 19a and the second terminal 19b.

[0057] (5) It is preferable that the thickness dimension T1 of the plate body portion 20 and the thickness dimension T2 of the thin-walled portion 21 satisfy the relationship expressed by formula (1) above. In this case, it is possible to further promote the generation of heat by the thin-walled portion 21 and suppress the reduction in strength of the bushing plate 15 due to the thin-walled portion 21.

[0058] (6) The thin-walled portion 21 of the bushing plate 15 is formed by a groove that opens to the lower side of the bushing plate 15. In this case, for example, it is possible to avoid the formation of irregularities on the upper surface of the bushing plate 15, which is the inner surface of the bushing 13, due to the thin-walled portion 21, or to reduce the irregularities formed on the upper surface of the bushing plate 15. For this reason, for example, it is possible to smoothly flow the molten glass MG along the upper surface of the bushing plate 15.

[0059] (7) It is preferable that the bushing plate 15 be constructed as an integral structure without welded parts. In this case, it is possible to suppress the occurrence of unintended uneven heating when the bushing plate 15 is heated by electric current.

[0060] <Examples of Modifications> The above embodiment can be implemented with the following modifications. The above embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0061] The position of the thin-walled portion 21 of the bushing plate 15 is not limited to the area between the first nozzle group 14a and the second nozzle group 14b. Furthermore, although the thin-walled portion 21 is provided so as to extend from the outer peripheral edge of the bushing plate 15, it is not limited to this. The position of the thin-walled portion 21 of the bushing plate 15 can be set according to the location on the bushing plate 15 that is prone to temperature drops due to various ambient environmental influences.

[0062] - The thickness dimension of the thin-walled portion 21 of the bushing plate 15 can be configured to differ in the longitudinal direction of the thin-walled portion 21. For example, as shown in Figure 4, the thickness dimension T2a of both ends A, A in the longitudinal direction of the thin-walled portion 21 of the bushing plate 15 may be smaller than the thickness dimension T2b of the intermediate portion B between both ends A, A in the longitudinal direction of the thin-walled portion 21. In this case, the heat generation at both ends A, A in the longitudinal direction of the thin-walled portion 21 can be promoted more than at the intermediate portion B. For this reason, for example, when using the bushing device 12 in an environment where the temperature of both ends A, A in the longitudinal direction of the thin-walled portion 21 of the bushing plate 15 is more likely to decrease than at the intermediate portion B, it is advantageous in terms of improving the uniformity of the temperature of the bushing plate 15. In addition, by having a thickness dimension of the intermediate portion B of the thin-walled portion 21 that is larger than the thickness dimension of both ends A, A of the thin-walled portion 21, it is possible to suppress a decrease in the strength of the bushing plate 15.

[0063] Furthermore, although not shown in the illustration, for example, the thickness dimensions of both ends A, A in the longitudinal direction of the thin-walled portion 21 of the bushing plate 15 may be made larger than the thickness dimension of the intermediate portion B between both ends A, A in the longitudinal direction of the thin-walled portion 21.

[0064] The number of thin-walled portions 21 on the bushing plate 15 may be one, or there may be multiple thin-walled portions spaced apart from each other. For example, as shown in Figure 5, the first thin-walled portion 21a and the second thin-walled portion 21b can be arranged corresponding to the first end edge E1 and the second end edge E2 of the bushing plate 15, respectively. In this case, the intermediate portion B between the first thin-walled portion 21a and the second thin-walled portion 21b of the bushing plate 15 makes it easy to ensure the strength of the bushing plate 15.

[0065] Furthermore, in a bushing 13 having three or more nozzle groups 14, thin-walled portions 21 can be arranged between adjacent nozzle groups 14. For example, the bushing 13 shown in Figure 6 has a first nozzle group 14a and a second nozzle group 14b, as well as a third nozzle group 14c consisting of a plurality of third nozzles N3. A third glass filament group (not shown) is drawn out from the third nozzle group 14c. A third glass strand is obtained by bundling the third glass filament group. The bushing plate 15 of this bushing 13 has a second plate body portion 20b and a third plate body portion 20c adjacent to it. The bushing plate 15 has a third outer peripheral portion 22c adjacent to the outer circumference of the third plate body portion 20c. The bushing plate 15 has a first thin-walled portion 21a provided between the first outer peripheral portion 22a and the second outer peripheral portion 22b, and a second thin-walled portion 21b provided between the second outer peripheral portion 22b and the third outer peripheral portion 22c.

[0066] - As shown in Figure 5, the thin-walled portion 21 of the bushing plate 15 can be provided so as not to divide the space between the first terminal 19a and the second terminal 19b. - As shown in Figure 5, the thin-walled portion 21 of the bushing plate 15 can also be provided so as not to cross the pair of long sides of the bushing plate 15. Although not shown in the figure, the thin-walled portion 21 can also be provided so as to cross the pair of short sides of the bushing plate 15.

[0067] The first plate body portion 20a and the second plate body portion 20b of the bushing plate 15 are arranged along the longitudinal direction of the bushing plate 15, but they may also be arranged along the short direction of the bushing plate 15.

[0068] - The second nozzle group 14b of the bushing 13 may be omitted. That is, the second plate body portion 20b and the second outer peripheral portion 22b of the bushing plate 15 may be omitted. - The thin-walled portion 21 of the bushing plate 15 is not limited to a groove that opens downwards of the bushing plate 15, but may also be a groove that opens upwards of the bushing plate 15. Furthermore, the thin-walled portion 21 may be composed of both a groove that opens upwards and a groove that opens downwards. In this case, from the viewpoint of reducing unevenness on the upper surface of the bushing plate 15, it is preferable that the depth of the groove that opens upwards is shallower than the depth of the groove that opens downwards.

[0069] The bushing device 12 may have three or more terminals 19.

[0070] 12...Bushing device 13...Bushing 14...Nozzle group 14a...First nozzle group 14b...Second nozzle group 15...Bushing plate 19...Terminal 19a...First terminal 19b...Second terminal 20...Plate body 20a...First plate body 20b...Second plate body 21...Thin-walled section A...End section B...Middle section GF...Glass filament GS...Glass strand GS1...First glass strand GS2...Second glass strand MG...Molten glass N1...First nozzle group N2...Second nozzle group T1, T2...Thickness dimensions

Claims

1. A bushing apparatus used in the manufacture of glass fibers, comprising a bushing having a group of nozzles for discharging molten glass and a bushing plate on which the group of nozzles is provided, wherein the bushing apparatus comprises a terminal for electrically heating the bushing plate, and the bushing plate has a plate body portion on which the group of nozzles is arranged and a thin-walled portion having a thickness smaller than that of the plate body portion.

2. The bushing device according to claim 1, wherein the thin-walled portion is provided so as to extend from the outer peripheral edge of the bushing plate.

3. The bushing device according to claim 1, wherein the plate body portion includes a first plate body portion on which a first nozzle group is arranged, and a second plate body portion on which a second nozzle group adjacent to the first nozzle group is arranged, and the thin-walled portion is provided between the first plate body portion and the second plate body portion.

4. The bushing device according to claim 1, wherein the terminal includes a first terminal and a second terminal arranged opposite to the first terminal, and the thin-walled portion is provided to divide the space between the first terminal and the second terminal in a plan view of the bushing plate.

5. The bushing device according to claim 1, wherein when the thickness dimension of the plate body is T1 and the thickness dimension of the thin-walled portion is T2, T1 and T2 satisfy the relationship expressed by the following formula (1): 0.75 × T1 ≤ T2 ≤ 0.95 × T1 ... (1).

6. The bushing device according to claim 1, wherein the thin-walled portion has a longitudinal direction, and the thickness dimension of both ends of the thin-walled portion in the longitudinal direction is smaller than the thickness dimension of the intermediate portion between the two ends.

7. The bushing device according to claim 1, wherein the thin-walled portion is formed by a groove that opens below the bushing plate.

8. The bushing device according to claim 1, wherein the bushing plate is constructed as an integral structure without a welded portion.

9. A method for manufacturing glass fibers, comprising a molding step of forming glass fibers using a bushing device according to any one of claims 1 to 8, wherein the bushing plate is electrically heated in the molding step.

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