Nozzle for glass fiber manufacturing, glass fiber manufacturing apparatus, and glass fiber manufacturing method

Abstract

To stably manufacture an irregular sectioned glass fiber with a non-circular cross section such as a flat shape.SOLUTION: A glass fiber manufacturing nozzle 5 comprises a pair of long wall parts opposed to each other in a minor diameter direction of a nozzle hole, and a pair of short wall parts opposed to each other in a major diameter direction of the nozzle hole. A notch part 54 is formed on at least one of the pair of the long wall parts. The notch part 54 comprises a first portion 54a shifted to one end side of a major diameter direction Y from a center part of the major diameter direction Y toward a tip end side from a base end side of the long wall part 51, and a second portion 54b shifted to the other end side of the major diameter direction Y from the center part of the major diameter direction Y toward the tip end side from the base end side of the long wall part 51. The first portion 54a and the second portion 54b are respectively formed into a staircases shape having 2 or more steps.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an improvement in the manufacturing technology of glass fibers.

Background Art

[0002] Glass fibers having a non-circular cross-section (hereinafter sometimes referred to as "non-circular cross-section glass fibers") with a non-circular cross-section such as an oval or elliptical flat shape are used in various fields because they can achieve a high reinforcing effect when mixed with a resin to form a composite.

[0003] This type of non-circular cross-section glass fiber is generally manufactured by cooling while pulling molten glass from a nozzle. At this time, since the shape of the nozzle hole at the tip of the nozzle forms the basis of the cross-sectional shape of the manufactured glass fiber, when manufacturing non-circular cross-section glass fibers, the nozzle hole is often made flat at the tip of the nozzle.

[0004] However, even when using a nozzle having a flat nozzle hole, if the viscosity of the molten glass drawn from the nozzle is too low, the cross-section of the molten glass is likely to become round due to surface tension at the tip of the nozzle, and it becomes impossible to manufacture the desired non-circular cross-section glass fiber.

[0005] Therefore, for example, in the nozzle disclosed in Patent Document 1, at the tip of the nozzle where the molten glass flows out, concave notch portions are provided on a pair of long wall portions facing each other in the minor axis direction of the flat nozzle hole. Thereby, the molten glass comes into contact with the outside air through the notch portion and is cooled, and the viscosity of the molten glass at the tip of the nozzle increases. As a result, it can be expected that it becomes easier to manufacture non-circular cross-section glass fibers.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] As disclosed in Patent Document 1, when the shape of the notch is substantially rectangular, the force that causes the molten glass to curl due to surface tension at the tip of the nozzle cannot be sufficiently suppressed, and it may not be possible to stably manufacture glass fibers with irregular cross-sections.

[0008] In view of the above circumstances, the present invention aims to stably produce glass fibers with irregular cross-sections having non-circular cross-sections, such as flattened shapes. [Means for solving the problem]

[0009] (1) The glass fiber manufacturing nozzle according to the present invention, which was devised to solve the above problems, comprises a flat nozzle hole through which molten glass flows out and a wall portion surrounding the nozzle hole, wherein the wall portion has a pair of long wall portions facing each other in the minor axis direction of the nozzle hole and a pair of short wall portions facing each other in the major axis direction of the nozzle hole, wherein a notch portion is formed in at least one of the pair of long wall portions, and the notch portion comprises a first portion which transitions from the central portion in the major axis direction to one end portion in the major axis direction as the long wall portion moves from the base end side to the tip side, and a second portion which transitions from the central portion in the major axis direction to the other end portion in the major axis direction as the long wall portion moves from the base end side to the tip side, and each of the first portion and the second portion has a staircase shape with two or more steps.

[0010] In this way, the molten glass is cooled by contact with the outside air through the notch. Furthermore, because the notch has a stepped shape, when the molten glass in contact with the notch tries to curl due to surface tension, the stepped shape provides resistance to the force that the molten glass tries to curl. In particular, the corners included in the stepped shape of the notch provide significant resistance to the molten glass. Therefore, the synergistic effect of the cooling effect of the notch and the resistance effect of the stepped shape of the notch reliably suppresses the force that the molten glass tries to curl. As a result, glass fibers with irregular cross-sections, such as flattened shapes, can be manufactured stably.

[0011] (2) In the configuration of (1) above, it is preferable that the number of steps in the staircase shape of the first part and the number of steps in the staircase shape of the second part are both 2, and that when the number of steps in the staircase shape of the first part and the number of steps in the staircase shape of the second part are counted sequentially from the base end of the long wall, the height of the nth step of the first part (where n is an integer from 0 to 2) is the same as the height of the nth step of the second part.

[0012] This method can reduce the manufacturing cost of the nozzle.

[0013] (3) In the configuration of (2) above, it is preferable that the sum of the width dimensions of the 0th stage of the first part and the second part is greater than the sum of the width dimensions of the 1st stage of the first part and the second part.

[0014] This method allows for a larger opening area in the central part along the long axis, thereby enhancing the cooling effect of the notch while maintaining the resistance-adding effect of the stepped shape of the notch. In other words, the force that causes the molten glass to curl is further suppressed.

[0015] (4) In the configuration of (2) or (3) above, it is preferable that the sum of the width dimensions of the 0th stage of the first part and the second part is 1 / 2 or more of the sum of the width dimensions of the 2nd stage of the first part and the second part.

[0016] This method allows for a larger opening area in the central part along the long axis, thereby enhancing the cooling effect of the notch while maintaining the resistance-adding effect of the stepped shape of the notch. In other words, the force that causes the molten glass to curl is further suppressed.

[0017] (5) In any of the configurations described in (2) to (4) above, it is preferable that the sum of the width dimensions of the 0th row of the first part and the second part is greater than the sum of the width dimensions of the 1st row of the first part and the second part, and that the sum of the width dimensions of the 1st row of the first part and the second part is greater than the sum of the width dimensions of the 2nd row of the first part and the second part.

[0018] By doing so, the corners included in the stepped shape that imparts a large resistance to the molten glass can be intensively positioned on the outer side in the major axis direction, so that the force that causes the molten glass to round is more suppressed.

[0019] (6) In any of the configurations of (2) to (5) above, it is preferable that the height dimension of the first step based on the height of the 0th step of the first part and the second part is larger than the height dimension of the second step based on the height of the first step of the first part and the second part.

[0020] By doing so, the opening area of the notch portion in the central portion in the major axis direction can be increased, so that the cooling effect by the notch portion can be enhanced while maintaining the resistance-imparting effect by the stepped shape of the notch portion. That is, the force that causes the molten glass to round is more suppressed.

[0021] (7) The glass fiber manufacturing apparatus according to the present invention devised to solve the above problems includes a bushing in which a plurality of nozzles having any of the configurations of (1) to (6) above are provided at the bottom.

[0022] By doing so, the same operational effects as those of the corresponding configurations described above can be enjoyed.

[0023] (8) The glass fiber manufacturing method according to the present invention devised to solve the above problems is characterized by manufacturing glass fibers using a nozzle having any of the configurations of (1) to (6) above.

[0024] By doing so, the same operational effects as those of the corresponding configurations described above can be enjoyed.

Effects of the Invention

[0025] According to the present invention, glass fibers with a deformed cross-section can be stably manufactured.

Brief Description of the Drawings

[0026] [Figure 1] This is a cross-sectional view showing a glass fiber manufacturing apparatus according to the first embodiment of the present invention. [Figure 2] This is a perspective view showing a nozzle according to the first embodiment of the present invention. [Figure 3] This is a view from arrow A in Figure 2. [Figure 4] This is a side view corresponding to the view taken by arrow A in Figure 2, showing a nozzle according to the second embodiment of the present invention. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the accompanying drawings. In each embodiment, corresponding components will be denoted by the same reference numerals, and redundant explanations may be omitted. When only a part of the configuration is described in each embodiment, the configuration of other embodiments described earlier can be applied to the other parts of that configuration. Furthermore, not only the combinations of configurations explicitly stated in the description of each embodiment, but also the configurations of multiple embodiments can be partially combined even if not explicitly stated, as long as there are no particular problems with the combination.

[0028] <First Embodiment> (Glass fiber manufacturing equipment) As shown in Figure 1, the glass fiber manufacturing apparatus according to the first embodiment comprises a glass melting furnace 1, a fore hearth 2 connected to the glass melting furnace 1, and a feeder 3 connected to the fore hearth 2. Here, in the orthogonal coordinate system consisting of XYZ shown in Figure 1, the X and Y directions are horizontal, and the Z direction is vertical.

[0029] The bottom of the feeder 3 is formed by a bushing 4. The bushing 4 is attached to the feeder 3 via a bushing block or the like. Multiple nozzles 5 are provided at the bottom of the bushing 4.

[0030] The glass melting furnace 1, fore hearth 2, feeder 3, bushing 4, and nozzle 5 are at least partially made of platinum or a platinum alloy (for example, a platinum-rhodium alloy). The detailed structure of the nozzle 5 will be described later.

[0031] Cooling means for cooling the molten glass G may be provided near each nozzle 5. Examples of cooling means include cooling pipes through which a refrigerant (e.g., cooling water) circulates, and cooling fins that induce airflow to exert a cooling effect.

[0032] (Method for manufacturing glass fibers) In the glass fiber manufacturing method according to this embodiment, the above-described glass fiber manufacturing apparatus is used. Specifically, as shown in Figure 1, in this manufacturing method, molten glass G is supplied from the glass melting furnace 1 through the fore hearth 2 to the feeder 3 and stored in the feeder 3. The molten glass G stored in the feeder 3 is drawn downward from a plurality of nozzles 5 provided on the bushing 4 to produce glass fibers (monofilaments) Gm. At this time, the viscosity of the molten glass G at the molding temperature is 10 2.0 ~10 3·5 dPa·s (preferably 10) 2.5 ~10 3·3 The viscosity is set within the range of dPa·s). The viscosity of the molten glass G at the molding temperature is the viscosity of the molten glass G at the point where it flows into the nozzle 5. A sizing agent is applied to the surface of the glass fibers Gm using an applicator (not shown), and 100 to 10,000 glass fibers Gm are spun into a single strand Gs. The spun strand Gs is wound as a fiber bundle Gr onto the bobbin 6 of the winding device. The strand Gs is cut to a predetermined length of, for example, 1 to 20 mm and used as chopped strand.

[0033] To adjust the viscosity of the molten glass G, one or more elements selected from the fore hearth 2, feeder 3, and bushing 4 may be heated by electric heating or other means.

[0034] The glass material of molten glass G is not particularly limited, but for example, E glass, D glass, S glass, AR glass, C glass, etc. can be used.

[0035] (nozzle) As shown in Figures 2 and 3, the nozzle 5 according to this embodiment comprises a pair of long wall portions 51 facing each other in the X direction, a pair of short wall portions 52 facing each other in the Y direction, and a flattened nozzle hole 53 partitioned by the long wall portions 51 and the short wall portions 52. The major axis direction of the nozzle hole 53 coincides with the Y direction, and the minor axis direction of the nozzle hole 53 coincides with the X direction. Hereinafter, the Y direction may be referred to as the major axis direction Y, and the X direction as the minor axis direction X.

[0036] The shape of the nozzle hole 53 is not particularly limited, but in this embodiment it is an elongated rectangle in the major axis direction Y.

[0037] Each of the short wall portions 52 in the short-axis direction X is connected to one end of the long wall portion 51 in the long-axis direction Y. The inner surfaces of the pair of short wall portions 52 and the pair of long wall portions 51 are continuous in the circumferential direction of the nozzle hole 53.

[0038] The dimension of the short wall portion 52 in the minor axis direction X is shorter than the dimension of the long wall portion 51 in the major axis direction Y. Preferably, the dimension of the short wall portion 52 in the minor axis direction X is 0.1 to 0.5 times the dimension of the long wall portion 51 in the major axis direction Y, and more preferably 0.2 to 0.4 times.

[0039] Each of the pair of elongated wall sections 51 is provided with a notch 54.

[0040] The notch 54 comprises a first portion 54a that transitions from the center of the major axis Y to one end of the major axis Y as it moves from the base end to the tip end of the long wall portion 51, and a second portion 54b that transitions from the center of the major axis Y to the other end of the major axis Y as it moves from the base end to the tip end of the long wall portion 51. In this embodiment, of the notch 54, one side with the center line CL of the major axis Y of the long wall portion 51 as the boundary is the first portion 54a, and the other side is the second portion 54b. The base end of the long wall portion 51 coincides with the upper end of the long wall portion 51 when the nozzle 5 is attached to the bottom of the feeder 3, and the tip end of the long wall portion 54 coincides with the lower end of the long wall portion 51 when the nozzle 5 is attached to the bottom of the feeder 3. In the following description, the base end side may be referred to as the upper end, and the tip end side as the lower end.

[0041] Each of the first part 54a and the second part 54b has a staircase shape with two or more steps. In this embodiment, we will describe the case where the number of steps in the staircase shape of the first part 54a and the number of steps in the staircase shape of the second part 54b are both two. For each of the first part 54a and the second part 54b, the steps are numbered 0, 1, and 2 in order from the base end side (upper end side) of the long wall portion 51.

[0042] Each of the first part 54a and the second part 54b includes a zero-stage horizontal section 55a, 55b extending in the horizontal direction (e.g., horizontal direction Y) as the zero-stage.

[0043] Each of the first part 54a and the second part 54b comprises, as the first stage, a first-stage horizontal section 56a, 56b extending horizontally, and a first-stage vertical section 57a, 57b extending vertically (e.g., vertical Z) connecting the outer ends of the zero-stage horizontal section 55a, 55b and the inner ends of the first-stage horizontal section 56a, 56b. Corners C0a, C0b are formed at the positions where the outer ends of the zero-stage horizontal section 55a, 55b and the upper ends of the first-stage vertical section 57a, 57b intersect. Corners C1a, C1b are formed at the positions where the lower ends of the first-stage vertical section 57a, 57b and the inner ends of the first-stage horizontal section 56a, 56b intersect. The angles θ0a, θ0b of corners C0a, C0b and θ1a, θ1b of corners C1a, C1b are 90°.

[0044] Each of the first part 54a and the second part 54b comprises, as a second stage, second horizontal sections 58a and 58b extending horizontally, and second vertical sections 59a and 59b extending vertically, connecting the outer ends of the first horizontal sections 56a and 56b to the inner ends of the second horizontal sections 58a and 58b. Corners C2a and C2b are formed where the outer ends of the first horizontal sections 56a and 56b intersect with the upper ends of the second vertical sections 59a and 59b. Corners C3a and C3b are formed where the lower ends of the second vertical sections 59a and 59b intersect with the inner ends of the second horizontal sections 58a and 58b. The angles θ2a and θ2b of corners C2a and C2b and the angles θ3a and θ3b of corners C3a and C3b are 90°.

[0045] With the above configuration, the molten glass G at the tip of the nozzle 5 comes into contact with the outside air through the notch 54 and is cooled. Furthermore, because the notch 54 has a stepped shape, when the molten glass G in contact with the notch 54 tries to curl due to surface tension, the stepped shape provides resistance to the force that causes the molten glass G to curl (the force that pulls the molten glass G toward the center in the major axis direction Y). In particular, the corners C0a~C3a and C0b~C3b included in the stepped shape of the notch 54 provide significant resistance to the molten glass G. Therefore, the synergistic effect of the cooling effect of the notch 54 and the resistance effect of the stepped shape of the notch 54 reliably suppresses the force that causes the molten glass G to curl. As a result, glass fibers Gm with irregular cross-sections such as flattened shapes can be stably manufactured. In particular, it becomes easier to manufacture glass fibers Gm with a high flatness ratio (horizontal dimension / vertical dimension in the cross-section perpendicular to the vertical direction Z).

[0046] The height of the nth (where n is an integer from 0 to 2)th step of the first part 54a is the same as the height of the nth step of the second part 54b. In other words, the horizontal section 55a of the 0th step of the first part 54a is the same height as the horizontal section 55b of the 0th step of the second part 54b. The horizontal section 56a of the 1st step of the first part 54a is the same height as the horizontal section 56b of the 1st step of the second part 54b. The horizontal section 58a of the 2nd step of the first part 54a is the same height as the horizontal section 58b of the 2nd step of the second part 54b. This makes it easier to process the nozzle 5 and reduces the manufacturing cost of the nozzle 5.

[0047] It is preferable that the sum of the width dimension W0a of the first section 54a's 0th step horizontal section 55a and the width dimension W0b of the second section 54b's 0th step horizontal section 55b (W0a + W0b) is at least half of the sum of the width dimension W2a of the second section 54a's 2nd step horizontal section 58a and the width dimension W2a of the second section 54b's 2nd step horizontal section 58b (W2a + W2b). In this way, the opening area of ​​the notch 54 in the center of the major axis direction Y can be increased, thereby enhancing the cooling effect of the notch 54 while maintaining the resistance-adding effect of the stepped shape of the notch 54. In other words, the force that causes the molten glass G to curl is further suppressed.

[0048] It is preferable that the sum of the width dimension W0a of the first section 54a's 0th row horizontal section 55a and the width dimension W0b of the second section 54b's 0th row horizontal section 55b (W0a + W0b) is greater than the sum of the width dimension W1a of the first section 54a's 1st row horizontal section 56a and the width dimension W1b of the second section 54b's 1st row horizontal section 56b (W1a + W1b). Furthermore, it is preferable that the sum of the width dimension W1a of the first section 54a's 1st row horizontal section 56a and the width dimension W1b of the second section 54b's 1st row horizontal section 56b (W1a + W1b) is greater than the sum of the width dimension W2a of the second section 54a's 2nd row horizontal section 58a and the width dimension W2b of the second section 54b's 2nd row horizontal section 58b (W2a + W2b). By setting (W0a+W0b)>(W1a+W1b)>(W2a+W2b) in this way, the corners C0a~C3a and C0b~C3b, which provide significant resistance to the molten glass G, can be concentrated on the outside in the major axis direction Y. As a result, the force that causes the molten glass G to curl due to surface tension is further suppressed.

[0049] It is preferable that the height dimension H1 of the first-stage horizontal sections 56a and 56b, based on the height of the first-stage horizontal sections 55a and 55b, is greater than the height dimension H2 of the second-stage horizontal sections 58a and 58b, based on the height of the first-stage horizontal sections 56a and 56b. Specifically, it is preferable that H1 is 1.5 times or more H2. In this way, the opening area of ​​the notch 54 in the central part in the major axis direction Y can be increased, so that the cooling effect of the notch 54 can be enhanced while maintaining the resistance-adding effect of the stepped shape of the notch 54. In other words, the force that causes the molten glass G to curl is further suppressed.

[0050] The sum of the width dimension W2a of the second horizontal section 58a of the first section 54a and the width dimension W2b of the second horizontal section 58b of the second section 54b (W2a + W2b) is preferably 0.5 mm or more.

[0051] In the notch portion 54, the area of ​​the rectangular second opening (lower opening) defined by the four corners C2a, C3a, C3b, and C2b is preferably 1.5 times or less the area of ​​the rectangular first opening (upper opening) defined by the four corners C0a, C1a, C1b, and C0b. In this embodiment, when the first and second openings are rectangular, for example, the area of ​​the first opening can be calculated as (W0a + W0b) × H1, and the area of ​​the second opening can be calculated as (W0a + W0b + W1a + W1b) × H2.

[0052] The sum of the width dimension W0a of the first section 54a's 0th stage horizontal section 55a and the width dimension W0b of the second section 54b's 0th stage horizontal section 55b (W0a + W0b) is preferably 0.3 to 0.6 times the total width W of the nozzle 5.

[0053] The sum of the width dimension W1a of the first horizontal section 56a of the first section 54a and the width dimension W1b of the first horizontal section 56b of the second section 54b (W1a + W1b) is preferably 0.2 to 0.5 times the total width W of the nozzle 5.

[0054] The sum of the width dimension W2a of the second horizontal section 58a of the first section 54a and the width dimension W2b of the second horizontal section 58b of the second section 54b (W2a + W2b) is preferably 0.2 to 0.5 times the total width W of the nozzle 5.

[0055] <Second Embodiment> (nozzle) In the second embodiment, a modified nozzle will be described. As shown in Figure 4, in the nozzle 5 according to this embodiment, the angles θ0a to θ3a of the corners C0a to C3a and θ0b to θ3b of C0b to C3b are greater than 90°. In other words, the angles θ0a to θ3a of the corners C0a to C3a and θ0b to θ3b of C0b to C3b are not limited to 90° as in the first embodiment. In other words, the vertical portions 57a, 59a, 57b, and 59b are not limited to being parallel to the vertical direction Z, but may be inclined to move outward in the major axis direction Y as they move downward in the vertical direction Z.

[0056] The angles θ0a to θ3a of corners C0a to C3a and θ0b to θ3b of corners C0b to C3b are preferably 90° to 150°, and more preferably 90° to 135°. A portion of the angles θ0a to θ3a of corners C0a to C3a may be 90°, with the remainder exceeding 90°. However, from the viewpoint of suppressing non-uniformity in the flow of molten glass G between the first portion 54a and the second portion 54b, it is preferable that corresponding corners have the same angle. That is, it is preferable that corners C0a and C0b have the same angle. It is preferable that corners C1a and C1b have the same angle. It is preferable that corners C2a and C2b have the same angle. It is preferable that corners C3a and C3b have the same angle.

[0057] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented in various forms.

[0058] In the above embodiment, the case in which a notch 54 is provided in each of the pair of long wall portions 51 was described, but it is also possible to provide a notch 54 in only one of the long wall portions 51.

[0059] In the above embodiment, the lateral portions 55a, 56a, 58a, 55b, 56b, and 58b may be inclined with respect to the horizontal direction. However, from the viewpoint of suppressing uneven flow of molten glass G between the first portion 54a and the second portion 54b, it is preferable that the first portion 54a and the second portion 54b have a shape that is symmetrical with respect to the center line CL of the notch portion 54.

[0060] In the above embodiment, the angles θ0a to θ3a of corners C0a to C3a and θ0b to θ3b of corners C0b to C3b may be less than 90°. In other words, the angles θ0a to θ3a and θ0b to θ3b are not particularly limited and can be appropriately adjusted according to the viscosity of the molten glass G, the extraction speed of the molten glass G, the ambient temperature, etc.

[0061] In the above embodiment, the number of steps in the staircase shape of the first part 54a and the number of steps in the staircase shape of the second part 54b may be three or more. In this case, it is preferable to further include the following configurations (1) to (5). (1) The number of steps in the staircase shape of the first part 54a and the number of steps in the staircase shape of the second part 54b are both m (where m is an integer of 3 or more), and when the number of steps in the staircase shape of the first part 54a and the number of steps in the staircase shape of the second part 54b are counted sequentially from the base end side of the long wall part 51, the height of the k-th step of the first part 54a (where k is an integer from 0 to m) is the same as the height of the k-th step of the second part 54b. (2) In the configuration of (1) above, the sum of the width dimensions of the first section 54a and the second section 54b is greater than the sum of the width dimensions of the first section 1 of the first section 54a and the second section 54b. (3) In the configuration of (1) or (2) above, the sum of the width dimensions of the 0th row of the first part 54a and the second part 54b is 1 / 2 or more of the sum of the width dimensions of the mth row of the first part 54a and the second part 54b. (4) In any of the configurations described in (1) to (3) above, the sum of the width dimensions of the (k-1)th row of the first part 54a and the second part 54b is greater than the sum of the width dimensions of the kth row of the first part 54a and the second part 54b. (5) In any of the configurations (1) to (4) above, the height dimension of the k-th step, based on the height of the (k-1)-th step of the first part 54a and the second part 54b, is greater than the height dimension of the (k+1)-th step, based on the height of the k-th step of the first part 54a and the second part 54b. [Explanation of Symbols]

[0062] 1. Glass melting furnace 2 Forehaas 3 Feeders 4 Bushing 5 nozzles 6 bobbins 51 Long wall section 52 Short wall section 53 Nozzle holes 54 Notch 54a Part 1 54b Second part 55a,56a,58a side part 55b,56b,58b Side part 57a,59a Vertical section 57b,59b Vertical section C0a,C1a,C2a,C3a corner C0b,C1b,C2b,C3b corner CL center line G molten glass Gm glass fiber Gr fiber bundle Gs Strand X Minor axis direction (horizontal direction) Y major axis direction (horizontal direction) Z vertical direction

Claims

1. A glass fiber manufacturing nozzle comprising a flattened nozzle hole from which molten glass flows out, and a wall portion surrounding the nozzle hole, wherein the wall portion has a pair of long wall portions facing each other in the short-axis direction of the nozzle hole, and a pair of short wall portions facing each other in the long-axis direction of the nozzle hole, A notch is formed in at least one of the pair of elongated wall portions. The notch comprises a first portion that transitions from the central portion in the major axis direction to one end portion in the major axis direction as the long wall portion moves from the base end to the tip end, and a second portion that transitions from the central portion in the major axis direction to the other end portion in the major axis direction as the long wall portion moves from the base end to the tip end, A nozzle for manufacturing glass fibers, characterized in that each of the first and second parts has a staircase shape with two or more steps.

2. The number of steps in the staircase shape of the first part and the number of steps in the staircase shape of the second part are both 2 steps. The glass fiber manufacturing nozzle according to claim 1, wherein when the number of steps in the staircase shape of the first part and the number of steps in the staircase shape of the second part are counted sequentially from the base end side of the long wall, the height of the nth step (where n is an integer from 0 to 2) of the first part is the same as the height of the nth step of the second part.

3. The nozzle for manufacturing glass fibers according to claim 2, wherein the sum of the width dimensions of the first and second parts at the 0th stage is greater than the sum of the width dimensions of the first part at the 1st stage.

4. The nozzle for manufacturing glass fibers according to claim 2, wherein the sum of the width dimensions of the first and second sections is 1 / 2 or more of the sum of the width dimensions of the second section of the first and second sections.

5. The sum of the width dimensions of the first and second sections is greater than the sum of the width dimensions of the first section of the first and second sections. The nozzle for manufacturing glass fibers according to claim 2, wherein the sum of the width dimensions of the first stage of the first part and the second part is greater than the sum of the width dimensions of the second stage of the first part and the second part.

6. The glass fiber manufacturing nozzle according to claim 2, wherein the height dimension of the first stage, based on the height of the 0th stage of the first part and the second part, is greater than the height dimension of the second stage, based on the height of the first stage of the first part and the second part.

7. A glass fiber manufacturing apparatus characterized by comprising a bushing having a plurality of nozzles according to any one of claims 1 to 6 provided at its bottom.

8. A method for producing glass fibers, characterized by producing glass fibers using a nozzle described in any one of claims 1 to 6.

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