JP7393985B2 - Optical fiber preform manufacturing device and optical fiber preform manufacturing method - Google Patents

Description

The present invention relates to an optical fiber preform manufacturing apparatus and an optical fiber preform manufacturing method.

Patent Document 1 discloses a glass particle depositing body in which glass particles synthesized by the burner are deposited on the surface of the starting rod while reciprocating a burner array arranged to face a rotating starting rod in parallel with the starting rod. The manufacturing method is described. In addition, in the manufacturing method described in Patent Document 1, the supply of raw materials is sequentially started from the burner of the first burner array that is moving in the direction of deposition, which has reached the deposition start position of the starting rod, and The supply of raw materials is stopped sequentially from the burner that has reached the deposition end position. Furthermore, the manufacturing method described in Patent Document 1 reverses the movement direction of the burner array in which the supply of raw materials to all burners has stopped and returns it to the position before starting the supply of raw materials to the burners, so that glass fine particles are Repeat the operation to perform the deposition.

Patent Document 2 discloses that a starting member having dummy rods welded to both ends of a core rod is rotated around an axis while the starting member and a burner are relatively reciprocated to deposit glass particles on the surface of the starting member to form an optical fiber motherboard. A method of manufacturing the material is described. In the manufacturing method described in Patent Document 2, two or more relative reciprocating axes for relatively reciprocating the burner are arranged parallel to the starting member, a burner is attached to each moving axis facing the starting member, and the burner is attached at the end of the starting member. The moving speed of the burner on each moving axis is changed every time the burner turns back (traverse).

Patent No. 3521865 Patent No. 6245648

However, in the manufacturing method described in Patent Document 1, the supply of raw materials to the burner is unstable because the supply of raw materials to the burner is repeatedly started and stopped. As a result, it is difficult to manufacture a high quality glass particle deposit using the manufacturing method described in Patent Document 1.

Further, in the manufacturing method described in Patent Document 2, it is difficult to uniformly exhaust the burner that is folded and moved, so it is difficult to manufacture a high-quality optical fiber preform. In particular, when manufacturing a large optical fiber preform at high speed, it is difficult to manufacture a high-quality optical fiber preform using the manufacturing method described in Patent Document 2 due to the difficulty of uniform exhaustion.

In view of the above-mentioned problems, an object of the present invention is to provide an optical fiber preform manufacturing apparatus and an optical fiber preform manufacturing method that can manufacture high-quality optical fiber preforms with high efficiency.

According to one aspect of the present invention, the blank rod is rotatably gripped with the central axis of the blank rod as a rotation axis, and the grip is movable in a movement direction along the central axis of the blank rod in a first movable range. and forming a flame for generating glass particles to be deposited on the blank rod, and moving from the home position to the moving direction in a second movable range whose length in the moving direction is shorter than the first movable range. It has a plurality of movable burners, and a control section that controls the gripping section and the plurality of burners, and the control section controls the plurality of burners that have formed the flame while rotating the blank rod with the gripping section. An apparatus for manufacturing an optical fiber preform is provided, characterized in that the gripping section is moved while the burner is stopped, and the plurality of burners that have formed the flame are moved while the gripping section is stopped.

According to another aspect of the present invention, the blank rod is rotatably gripped with the central axis of the blank rod as a rotation axis, and the blank rod is movable in a movement direction along the central axis of the blank rod in a first movable range. a gripping portion and a flame for generating glass particles to be deposited on the blank rod, and a second movable range in which the length in the moving direction is shorter than the first movable range from the home position in the moving direction. A method for manufacturing an optical fiber preform using an apparatus for manufacturing an optical fiber preform having a plurality of burners movable to a plurality of burners, wherein the plurality of flames are formed while the blank rod is rotated by the gripping section. The light is characterized in that the glass particles are deposited on the blank rod by moving the gripping part while stopping the burner, and moving the plurality of burners that have formed the flame while stopping the gripping part. A method of manufacturing a fiber preform is provided.

According to the present invention, a high quality optical fiber preform can be manufactured with high efficiency.

FIG. 1 is a schematic diagram showing an optical fiber preform manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram (part 1) showing a method for manufacturing an optical fiber preform according to an embodiment of the present invention. FIG. 3 is a schematic diagram (Part 2) showing a method for manufacturing an optical fiber preform according to an embodiment of the present invention. FIG. 4 is a schematic diagram (Part 3) showing a method for manufacturing an optical fiber preform according to an embodiment of the present invention. FIG. 5 is a schematic diagram (Part 4) showing a method for manufacturing an optical fiber preform according to an embodiment of the present invention. FIG. 6 is a schematic diagram showing an optical fiber preform manufacturing apparatus according to a first reference example. FIG. 7 is a schematic diagram showing an optical fiber preform manufacturing apparatus according to a second reference example.

[One embodiment]
An apparatus for manufacturing an optical fiber preform and a method for manufacturing an optical fiber preform according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7.

Here, the directions used in the following explanation will be defined. First, let the direction along the horizontal direction be the X direction. Further, the direction along the vertical direction, which is a direction perpendicular to the X direction, is defined as the Z direction. Further, the direction along the direction orthogonal to the X direction and the Z direction is defined as the Y direction. Further, among the X directions, one direction is the +X direction, and the other direction opposite to the +X direction is the −X direction. Note that the X direction does not necessarily have to be a direction along the horizontal direction, but in that case, similarly, the direction along the direction perpendicular to the X direction is the Z direction, and the X direction and the Z direction. The direction along the direction perpendicular to can be defined as the Y direction. Moreover, the X direction, the Y direction, and the X direction are not necessarily limited to directions that are orthogonal to each other, but can also be defined as directions that intersect with each other.

First, the configuration of the optical fiber preform manufacturing apparatus according to the present embodiment will be described using FIG. 1. FIG. 1 is a schematic diagram showing an optical fiber preform manufacturing apparatus according to the present embodiment. FIG. 1(a) is a schematic diagram showing an optical fiber preform manufacturing apparatus viewed in the +Y direction. FIG. 1(b) is a schematic diagram showing the optical fiber preform manufacturing apparatus as viewed in the −X direction.

The optical fiber preform manufacturing apparatus according to this embodiment is a manufacturing apparatus that manufactures an optical fiber preform by, for example, an OVD (Outside Vapor Deposition) method. As shown in FIGS. 1(a) and 1(b), an optical fiber preform manufacturing apparatus 10 according to the present embodiment includes an apparatus base 12 and gripping parts 16a and 16b that grip a blank rod 14. ing. The optical fiber preform manufacturing apparatus 10 also includes a burner stand 18, a plurality of burners 20a, 20b, 20c, an exhaust hood 22, and a control device 24. In addition, in this embodiment, the case where the number of burners n is 3, in which three burners 20a, 20b, and 20c are installed, will be explained as an example, but the number n of burners is not particularly limited as long as it is a plurality of 2 or more. do not have.

The device base 12 functions as a support section that supports the grips 16a and 16b and the burner stand 18. The device base 12 supports the gripping parts 16a, 16b so that the gripping parts 16a, 16b can move in the X direction within a predetermined movable range, as will be described later. Further, the device base 12 supports a burner stand 18 at a central position of the device base 12 . The device base 12 is, for example, a platform-shaped, plate-shaped, or frame-shaped structure that supports the grips 16a, 16b and the burner stand 18 together or individually, although the device base 12 is not particularly limited.

The blank rod 14 is a cylindrical rod-shaped core material for forming an optical fiber preform. On the outer circumferential surface of the blank rod 14, glass fine particles of silica glass, for example, called soot, which are generated by a plurality of burners 20a, 20b, and 20c, are deposited as described later, and a porous light consisting of a deposit of glass fine particles is deposited. A fiber preform is formed. The deposited glass particles are not particularly limited and may vary depending on the manufacturing conditions, but are, for example, glass particles with a particle size of 0.01 μm to several μm.

The gripping parts 16a and 16b rotatably grip the blank rod 14 with the central axis of the blank rod 14 as a rotation axis. The gripping portions 16a and 16b are installed at a distance that allows them to grip the blank rod 14 in the X direction. The grip portion 16a rotatably grips one end of the blank rod 14, and the grip portion 16b rotatably grips the other end of the blank rod 14. Thereby, the gripping parts 16a and 16b grip the blank rod 14 so that the central axis of the blank rod 14 is along the X direction, and grip the blank rod 14 rotatably with the central axis of the blank rod 14 as a rotation axis.

Moreover, the gripping parts 16a and 16b are configured to rotate the blank rod 14 with the central axis of the blank rod 14 as a rotation axis under the control of the control device 24. The gripping parts 16a and 16b can change the rotational speed at which the blanking rod 14 is rotated under the control of the control device 24.

Moreover, the gripping parts 16a and 16b are configured to be movable in the X direction, which is the moving direction along the central axis of the blank rod 14, within a predetermined movable range under the control of the control device 24. Specifically, the gripping parts 16a and 16b are configured so that they can alternately move in the +X direction and the -X direction within a predetermined movable range on the device base 12 under the control of the control device 24. It is composed of The gripping parts 16a and 16b can change the speed and direction of movement in the +X direction and the -X direction under the control of the control device 24. The movement mechanism for the gripping parts 16a, 16b is not particularly limited, but may be, for example, a movement mechanism using a linear motor, a ball screw, or the like.

The movable range length, which is the length in the X direction of the movable range in which the gripping parts 16a and 16b alternately repeat movement in the +X direction and the -X direction, is L0. The movable range length L0 of the grips 16a, 16b is set longer than the movable range length L1 of the burners 20a, 20b, 20c, which will be described later.

The burner stand 18 is fixedly installed at the center of the device base 12 so as to be located on one side, which is the lower side, of the blank rod 14 held by the gripping parts 16a and 16b. The burner stand 18 supports the burners 20a, 20b, 20c so that the burners 20a, 20b, 20c can move within a predetermined movable range, as will be described later.

The plurality of burners 20a, 20b, and 20c are configured to be movable from their respective fixed positions in the X direction, which is the moving direction along the central axis of the blank rod 14, within a predetermined movable range under the control of the control device 24. . Specifically, the plurality of burners 20a, 20b, and 20c alternately move in the +X direction and in the -X direction within a predetermined movable range on the burner stand 18 under the control of the control device 24. It is configured so that it can be done.

The plurality of burners 20a, 20b, and 20c are a plurality of burners arranged diagonally with respect to the X direction at equal intervals in each of the X direction and the Y direction between one end and the other end in the X direction of the burner stand 18. Each position is set as a fixed position. Thereby, the plurality of burners 20a, 20b, and 20c are installed so as to be shifted in the Y direction, which is a direction that intersects with the X direction, which is the direction in which they move. Since the fixed positions of the plurality of burners 20a, 20b, 20c are arranged diagonally with respect to the X direction, each burner 20a, 20b, 20c can move in the +X direction and -X direction without interfering with each other. It is now possible to do so. The plurality of burners 20a, 20b, and 20c can change the speed and direction of movement in the +X direction and −X direction under the control of the control device 24. The movement mechanism for the plurality of burners 20a, 20b, and 20c is not particularly limited, but may be a movement mechanism using a linear motor, a ball screw, or the like, for example.

The movable range in which the plurality of burners 20a, 20b, and 20c alternately repeat movement in the +X direction and the -X direction is between the fixed position of the outermost burner 20a located at one end of the burner table 18 in the X direction and the other end. This is the range between the normal position of the outermost burner 20c. The movable range length L1, which is the length in the X direction of the movable range of the plurality of burners 20a, 20b, and 20c, is set shorter than the movable range length L0 of the grips 16a, 16b. In addition, the movable range length L1 of the plurality of burners 20a, 20b, and 20c is the normal position of one outermost burner 20a located at one end of the burner stand 18 in the X direction and the other outermost end located at the other end. This corresponds to the distance L3 between the burner 20c and the fixed position of the burner 20c.

Each of the burners 20a, 20b, and 20c forms a flame toward the blank rod 14 from its ejection port for producing glass particles. Preferably, each burner 20a, 20b, 20c forms a flame with a width smaller than the distance between the fixed positions of adjacent burners in the X and Y directions. In the case shown in FIG. 1(a), the normal position of one outermost burner 20a located at one end of the burner stand 18 in the X direction and the normal position of the other outermost burner 20c located at the other end The distance between them is L3. Using the distance L3, the distance between the fixed positions of adjacent burners in the X direction is expressed as L3×(1/2). Therefore, in this case, it is preferable that the width L2 of the flame in the X direction satisfies L2<L3×(1/2). Generalizing when the number of burners is n, it is preferable that the flame width L2 satisfies L2<L3×{1/(n−1)}. When the flame width L2 satisfies this relationship, mutual interference between the flames formed by the burners 20a, 20b, and 20c can be avoided and the deposition efficiency of glass particles can be improved. It is preferable that the width of the flame also satisfy the same relationship in the Y direction as in the X direction.

Note that the width of the flame is, for example, the same as the diameter of the outermost layer of the flame forming gas jet nozzles formed concentrically in multiple layers at the flame jet ports of each burner 20a, 20b, and 20c. be able to. The flame forming gas contains, for example, a combustible gas such as hydrogen, and a combustion supporting gas such as oxygen.

The distance L3 between the regular position of one outermost burner 20a located at one end of the burner table 18 in the X direction and the regular position of the other outermost burner 20c located at the other end is the distance L3 between the blank rod 14 It is preferable that L3<L4×(1/2) be satisfied for the length L4. On the contrary, in the case of L3>L4×(1/2), the exhaust hood 22 is installed so as to face the area including the burners 20a and 20c located apart from each other by the distance L3, so the blank rod 14 The central portion of the air conditioner is constantly exposed to exhaust gas from an exhaust mechanism including the exhaust hood 22. Therefore, in the center of the blank rod 14, the surface temperature decreases and the deposition state of the glass particles becomes different from that in the surrounding area, which may cause the outer diameter of the optical fiber preform to be non-uniform. When the distance L3 satisfies L3<L4×(1/2), such non-uniformity of the outer diameter can be avoided. Note that since the distance L3 matches the movable range length L1 of the plurality of burners 20a, 20b, and 20c, the movable range length L1 can also satisfy the same relationship as L3.

The plurality of burners 20a, 20b, and 20c form a flame from their jet ports and introduce raw material gas into the flame, so that multiple types of gases including the flame-forming gas and the raw material gas are supplied. There is. The multiple types of gases supplied to the multiple burners 20a, 20b, and 20c include, for example, hydrogen gas, oxygen gas, argon gas, source gas, and the like. The raw material gas contains silicon tetrachloride and the like. Argon gas is appropriately used as a carrier gas or the like. In each burner 20a, 20b, 20c, an oxyhydrogen flame is formed by combustion of hydrogen gas and oxygen gas, and a raw material gas is introduced into the oxyhydrogen flame. When the raw material gas introduced into the flame undergoes flame hydrolysis, glass fine particles are generated and deposited on the outer peripheral surface of the blank rod 14 .

The plurality of burners 20a, 20b, and 20c are installed on the burner stand 18 with appropriate inclinations depending on their positions in the Y direction so that the respective flame jet ports face the central axis of the blank rod 14. In the case shown in FIGS. 1(a) and 1(b), the burners 20a and 20c, which are located diagonally below the blank rod 14, are installed so that their respective jet outlets are slanted toward the central axis of the blank rod 14. has been done. On the other hand, the burner 20b located directly below the blank rod 14 is installed without being inclined so that its ejection port faces the central axis of the blank rod 14 located directly above. The distance between each burner 20a, 20b, 20c and blank rod 14 is set to a distance that allows glass particles generated by each burner 20a, 20b, 20c to be deposited on blank rod 14.

The exhaust hood 22 is installed so as to face the burner stand 18 via the blank rod 14 so as to face a region of the burner stand 18 that includes the movable range of the plurality of burners 20a, 20b, and 20c. An exhaust fan (not shown) is connected to the exhaust hood 22. The exhaust hood 22 functions, together with an exhaust fan, as an exhaust mechanism that exhausts gas from a space between the exhaust hood 22 and a region of the burner stand 18 that includes the movable range of the plurality of burners 20a, 20b, and 20c. The exhaust hood 22 can stabilize the flames of the plurality of burners 20a, 20b, 20c by exhausting gas containing excess glass particles generated by the plurality of burners 20a, 20b, 20c. .

The control device 24 is an information processing device that functions as a control section that manages and controls each part of the optical fiber preform manufacturing apparatus 10 while manufacturing the optical fiber preform by depositing glass particles onto the blank rod 14. . The control device 24 includes a CPU (Central Processing Unit) (not shown) that executes various operations such as calculation, control, and discrimination. The control device 24 also has a storage device (not shown) that stores various control programs executed by the CPU, databases referenced by the CPU, and the like. The control device 24 also includes a RAM (Random Access Memory) (not shown) that temporarily stores data being processed by the CPU, input data, and the like.

Although the control device 24 is not particularly limited, it can be configured by a general-purpose computer device such as a personal computer, or it can be configured by a computer device dedicated to the optical fiber preform manufacturing apparatus 10. can. Further, each function of the control device 24 can be realized by a single computer device or by a plurality of computer devices.

The control device 24 is communicatively connected to an exhaust mechanism including, for example, the grips 16a, 16b, a plurality of burners 20a, 20b, 20c, and the exhaust hood 22. This makes it possible for the control device 24 to control each part of the optical fiber preform manufacturing apparatus 10, such as the gripping parts 16a and 16b, the plurality of burners 20a, 20b, and 20c, and the exhaust mechanism including the exhaust hood 22. ing.

Further, the control device 24 can control the rotation speed of the blank rod 14 by the grips 16a, 16b by controlling the grips 16a, 16b. Furthermore, the control device 24 can control the movement of the gripping parts 16a, 16b and the plurality of burners 20a, 20b, 20c forming flames as described below while rotating the blank rod 14 with the gripping parts 16a, 16b. can.

The control device 24 can control the movement of the grips 16a, 16b and the movement of the plurality of burners 20a, 20b, 20c. That is, the control device 24 can control the moving speed and direction of the gripping parts 16a, 16b by controlling the gripping parts 16a, 16b. Further, the control device 24 can control the moving speed and moving direction of the plurality of burners 20a, 20b, and 20c.

Further, the control device 24 can control the timing of moving the grips 16a, 16b and the plurality of burners 20a, 20b, 20c such that one of them is stopped while the other is moved. That is, the control device 24 can control the timing at which the grips 16a, 16b and the plurality of burners 20a, 20b, 20c are moved so that they are not moved at the same time. Specifically, the control device 24 maintains the plurality of burners 20a, 20b, and 20c in a stopped state while moving the grips 16a and 16b. Further, the control device 24 maintains the grip portions 16a, 16b in a stopped state while moving the plurality of burners 20a, 20b, 20c.

In this way, the control device 24 can move the grips 16a, 16b while rotating the blank rod 14 with the grips 16a, 16b while stopping the plurality of burners 20a, 20b, 20c that have formed flames. . Further, the control device 24 can move the plurality of burners 20a, 20b, and 20c that have formed flames while rotating the blank rod 14 using the grips 16a and 16b while stopping the grips 16a and 16b.

Further, the control device 24 can control the timing of moving the grips 16a, 16b and the plurality of burners 20a, 20b, 20c so as to alternately move them.

The control device 24 also controls the plurality of burners 20a, 20b, 20c, and controls the flow rate of various gases supplied to the plurality of burners 20a, 20b, 20c. The production of glass particles can be controlled by Further, the control device 24 can control exhaust by the exhaust mechanism including the exhaust hood 22.

In this way, the optical fiber preform manufacturing apparatus 10 according to this embodiment is configured.

Next, a method for manufacturing an optical fiber preform using the optical fiber preform manufacturing apparatus 10 according to the present embodiment will be further described with reference to FIGS. 2 to 5. 2 to 5 are schematic diagrams showing a method for manufacturing an optical fiber preform according to this embodiment. 2(a) and 2(b), FIG. 3(a) and FIG. 3(b), FIG. 4(a) and FIG. 4(b), and FIG. 5(a) and FIG. 5(b). 1 shows the optical fiber preform manufacturing apparatus 10 seen in the +Y direction in the same manner as FIG. 1(a) at each step in the optical fiber preform manufacturing method.

The optical fiber preform manufacturing apparatus 10 starts manufacturing an optical fiber preform from the following initial state. That is, in the initial state, as shown in FIG. 2(a), a plurality of burners 20a, 20b, and 20c are stopped at fixed positions at one end, the center, and the other end in the X direction, respectively, on the burner stand 18. In addition, in the initial state, the relative positional relationship in the X direction between one end of the blank rod 14 held by the gripping part 16a and the burner 20a located at the fixed position at the outermost end on the one end side is the first positional relationship. It has become. The first positional relationship is, for example, a positional relationship in which the position of one end of the blank rod 14 in the X direction and the position of the burner 20a in the X direction match each other. Note that the first positional relationship is not limited to this, and may be a predetermined relationship such as a positional relationship in which both positions in the X direction are close to each other by a predetermined distance.

The control device 24 controls the exhaust mechanism including the exhaust hood 22 to start the exhaust mechanism. Further, the control device 24 controls the plurality of burners 20a, 20b, and 20c to form a flame and start generating glass particles. Furthermore, the control device 24 controls the gripping parts 16a, 16b to start rotation of the blank rod 14 by the gripping parts 16a, 16b, and to start moving the gripping parts 16a, 16b in the -X direction. The control device 24 continuously supplies various gases including flame gas and source gas to each burner 20a, 20b, and 20c from the start to the end of manufacturing the optical fiber preform. Note that the control device 24 can appropriately change the rotational speed of the blank rod 14 by the gripping parts 16a, 16b, the flow rate of various gases supplied to each burner 20a, 20b, 20c, etc.

The gripping parts 16a and 16b move in the -X direction while rotating the blank rod 14, as shown in FIG. 2(b), under the control of the control device 24. While the grips 16a, 16b move in the -X direction, the plurality of burners 20a, 20b, 20c maintain a stopped state without moving in the X direction under the control of the control device 24, and form flames. There is. In this way, the control device 24 moves the grips 16a, 16b in the −X direction while rotating the blank rod 14 with the grips 16a, 16b while stopping the plurality of burners 20a, 20b, 20c that have formed flames. While the gripping parts 16a and 16b that grip the blank rod 14 move in the -X direction in this way, glass particles generated by the burners 20a, 20b, and 20c are deposited on the outer peripheral surface of the rotating blank rod 14. To go.

As the gripping parts 16a and 16b move in the -X direction, the other end of the blank rod 14 gripped by the gripping part 16b and the outermost end on the other end side are The relative positional relationship in the X direction with the burner 20c located at the second position is the second positional relationship. The second positional relationship is, for example, a positional relationship in which the position of the other end of the blank rod 14 in the X direction and the position of the burner 20c in the X direction match each other. Note that the second positional relationship is not limited to this, and may be a predetermined relationship such as a positional relationship in which both positions in the X direction are close to each other by a predetermined distance. When the relative positional relationship between the two becomes the second positional relationship, the control device 24 controls the gripping parts 16a, 16b to maintain the rotation of the blank rod 14 by the gripping parts 16a, 16b, and the gripping part 16a. , 16b stops moving in the -X direction.

Subsequently, with the grips 16a and 16b stopped, the control device 24 controls each burner 20a, 20b, and 20c to move the burner stand 18 as shown in FIGS. 3(a) and 3(b). At the top, each burner 20a, 20b, 20c is moved in the X direction. Specifically, under the control of the control device 24, the burner 20a starts moving in the +X direction from its home position toward the home position of the burner 20c. Under the control of the control device 24, the burner 20b starts reciprocating movement including movement from its home position in the +X direction via the home position of the burner 20c and back to its home position, and then movement in the −X direction. . Under the control of the control device 24, the burner 20c starts moving in the -X direction from its home position toward the home position of the burner 20a. While each burner 20a, 20b, 20c moves in the X direction, the grips 16a, 16b maintain a stopped state without moving in the X direction under the control of the control device 24.

In this way, the control device 24 controls the gripping portion 16a, Switching from movement of burner 16b to movement of a plurality of burners 20a, 20b, and 20c.

The burner 20a moves in the +X direction on the burner stand 18 and stops at the fixed position of the burner 20c. Further, the burner 20b moves in the +X direction on the burner stand 18, returns to the normal position of the burner 20c, and further moves in the -X direction and stops at the original normal position. Further, the burner 20c moves in the -X direction and stops at the regular position of the burner 20a. In this way, the control device 24 moves the plurality of burners 20a, 20b, and 20c that have formed flames in the X direction while rotating the blank rod 14 with the grips 16a and 16b and stopping the grips 16a and 16b. While each burner 20a, 20b, 20c moves in the X direction in this manner, glass particles generated by each burner 20a, 20b, 20c continue to accumulate on the outer peripheral surface of the rotating blank rod 14.

When each burner 20a, 20b, 20c stops, the control device 24 controls the gripping parts 16a, 16b to start moving the gripping parts 16a, 16b in the +X direction, as shown in FIG. 4(a). .

The gripping parts 16a and 16b move in the +X direction while continuing to rotate the blank rod 14 under the control of the control device 24. While the grips 16a and 16b move in the +X direction, the plurality of burners 20a, 20b, and 20c maintain a stopped state without moving in the X direction and form flames under the control of the control device 24. . In this way, the control device 24 moves the grips 16a, 16b in the +X direction while rotating the blank rod 14 with the grips 16a, 16b while stopping the plurality of burners 20a, 20b, 20c that have formed flames. While the gripping parts 16a and 16b that grip the blank rod 14 move in the +X direction in this way, glass particles generated by the burners 20a, 20b, and 20c are deposited on the outer peripheral surface of the rotating blank rod 14. go.

As the gripping parts 16a and 16b move in the +X direction, as shown in FIG. 4(b), one end of the blank rod 14 gripped by the gripping part 16a and the outermost end of the blank rod 14 are positioned at fixed positions on the one end side. The relative positional relationship in the X direction with the burner 20c is the third positional relationship. Similar to the first positional relationship, the third positional relationship is, for example, a positional relationship in which the position of one end of the blanking rod 14 in the X direction and the position of the burner 20c in the X direction match each other. Note that the third positional relationship is not limited to this, and may be a predetermined relationship such as a positional relationship in which both positions in the X direction are close to each other by a predetermined distance. When the relative positional relationship between the two becomes the third positional relationship, the control device 24 controls the gripping parts 16a, 16b to maintain the rotation of the blank rod 14 by the gripping parts 16a, 16b, and the gripping part 16a. , 16b stops moving in the +X direction.

Subsequently, while the gripping parts 16a and 16b are stopped, the control device 24 controls the plurality of burners 20a, 20b, and 20c, and as shown in FIG. 4(b) and FIG. 5(a), the control device 24 controls the burner stand. 18, each burner 20a, 20b, 20c is moved in the X direction. Specifically, under the control of the control device 24, the burner 20a starts moving in the +X direction from its home position toward the home position of the burner 20c. Under the control of the control device 24, the burner 20b starts reciprocating movement from its home position via the home position of the burner 20c and back to its home position in the -X direction and then in the +X direction. . Under the control of the control device 24, the burner 20c starts moving in the +X direction from its home position toward the home position of the burner 20a. While each burner 20a, 20b, 20c moves in the X direction, the grips 16a, 16b maintain a stopped state without moving in the X direction under the control of the control device 24.

In this way, the control device 24 controls the gripping parts 16a and 16b when the positional relationship between one end of the blanking rod 14 and the burner 20c located at the fixed position at the outermost end of the one end becomes the third positional relationship. Switching from movement to movement of a plurality of burners 20a, 20b, and 20c.

The burner 20a moves in the -X direction on the burner stand 18 and stops at the fixed position of the burner 20c. Further, the burner 20b moves in the −X direction on the burner stand 18, returns to the normal position of the burner 20c, moves in the +X direction, and stops at the original normal position. Moreover, the burner 20c moves in the +X direction and stops at the regular position of the burner 20a. In this way, the control device 24 moves the plurality of burners 20a, 20b, and 20c that have formed flames in the X direction while rotating the blank rod 14 with the grips 16a and 16b and stopping the grips 16a and 16b. While each burner 20a, 20b, 20c moves in the X direction in this way, glass particles generated by each burner 20a, 20b, 20c continue to accumulate on the outer peripheral surface of the rotating blank rod 14.

As shown in FIG. 5(b), when each burner 20a, 20b, 20c stops, the control device 24 controls the gripping portions 16a, 16b, and controls the gripping portion 16a as in the case shown in FIG. , 16b starts moving in the -X direction.

In this way, the control device 24 controls each part of the optical fiber preform manufacturing apparatus 10 and repeats the steps shown in FIG. 2(a) to FIG. 5(b) described above. As a result, glass fine particles are deposited on the outer peripheral surface of the blank rod 14 over the entire length of the blank rod 14.

The control device 24 controls the moving speed of the gripping parts 16a, 16b and the plurality of burners 20a, 20b so that the magnitude of the relative speed of the plurality of burners 20a, 20b, 20c with respect to the blank rod 14 is constant while repeating the process. , 20c can be controlled. That is, the control device 24 controls the magnitude of the relative speed of the plurality of burners 20a, 20b, 20c with respect to the blank rod 14 when moving the gripping parts 16a, 16b and when moving the plurality of burners 20a, 20b, 20c. can be maintained constant. By keeping the magnitude of the relative speed of the plurality of burners 20a, 20b, 20c with respect to the blank rod 14 constant, fluctuations in the outer diameter of the optical fiber preform can be suppressed to a smaller extent over the entire length in the longitudinal direction of the blank rod 14. I can do it.

The control device 24 controls each part of the optical fiber preform manufacturing apparatus 10 based on, for example, the result of detecting the weight change of the blank rod 14, the thickness of the deposited glass particles, the elapsed time from the start of manufacturing, etc. The operation of the optical fiber base material is stopped and the production of the optical fiber preform is completed.

In this way, a porous optical fiber preform having a predetermined outer diameter made of a deposit of glass particles is manufactured around the outer periphery of the blank rod 14. After the blank rod 14 is drawn out, the manufactured porous optical fiber preform is dehydrated and sintered by heating in a heating furnace such as an electric furnace to become a transparent optical fiber preform.

Unlike the optical fiber preform manufacturing apparatus 10 according to this embodiment, a configuration in which only one of the gripping parts 16a, 16b and the plurality of burners 20a, 20b, and 20c moves, and the other one is fixed, is also considered. However, with such a configuration, it is difficult to manufacture a high quality optical fiber preform. This point will be explained using FIGS. 6 and 7.

6(a) and 6(b) show an optical fiber preform manufacturing apparatus 110 according to a first reference example in which only the gripping parts 16a and 16b move and a plurality of burners 20a, 20b and 20c are fixed. FIG. Note that in FIGS. 6(a) and 6(b), the same reference numerals are given to structures corresponding to those shown in FIGS. 1(a) and 1(b).

As shown in FIGS. 6(a) and 6(b), in the first reference example, the plurality of burners 20a, 20b, 20c are fixed while the grips 16a, 16b move. In the first reference example, in order for the plurality of burners 20a, 20b, 20c to form flames toward the blank rod 14 over the entire length in the longitudinal direction of the blank rod 14, it is necessary to move the grips 16a, 16b in the X direction. The range needs to be extended. As a result, in the first reference example, it is not possible to avoid increasing the size of the apparatus configuration in the X direction of the optical fiber preform manufacturing apparatus 110. When the device configuration in the X direction becomes larger, the member that grips the blank rod 14 is bent, making it difficult to deposit glass particles uniformly over the entire length of the blank rod 14 in the longitudinal direction. Therefore, in the first reference example, it is difficult to manufacture a high-quality optical fiber preform, and a large edge loss may occur in the optical fiber preform, especially at one end and the other end of the blank rod 14.

On the other hand, FIG. 7 is a schematic diagram showing an optical fiber preform manufacturing apparatus 210 according to a second reference example in which the gripping parts 16a and 16b are fixed and only the plurality of burners 20a, 20b, and 20c are moved. Note that in FIG. 7, the same reference numerals are given to components corresponding to those shown in FIGS. 1(a) and 1(b).

As shown in FIG. 7, in the second reference example, the grips 16a, 16b are fixed, while the plurality of burners 20a, 20b, 20c are moved. In the second reference example, in order for the plurality of burners 20a, 20b, 20c to form a flame toward the blanking rod 14 over the entire length in the longitudinal direction of the blanking rod 14, the plurality of burners 20a, 20b in the X direction, It is necessary to lengthen the range of motion of 20c. Furthermore, in the second reference example, it is necessary to make the exhaust hood 22 larger in the X direction in conjunction with increasing the movable range of the plurality of burners 20a, 20b, and 20c in the X direction. However, with the large exhaust hood 22, it is difficult to uniformly exhaust the air, making it difficult to deposit glass particles uniformly over the entire length of the blank rod 14 in the longitudinal direction. Therefore, in the second reference example, it is difficult to manufacture a high-quality optical fiber preform.

In contrast to these first and second reference examples, the optical fiber preform manufacturing apparatus 10 according to the present embodiment has gripping parts 16a, 16b and a plurality of burners 20a, 20b while glass fine particles are deposited on the blank rod 14. , 20c moves. That is, in this embodiment, the grips 16a, 16b and the plurality of burners 20a, 20b, 20c move alternately. Therefore, in the optical fiber preform manufacturing apparatus 10 according to the present embodiment, a relatively small-sized device configuration can be adopted without increasing the size of the device configuration in the X direction. Furthermore, in the optical fiber preform manufacturing apparatus 10 according to this embodiment, there is no need to make the exhaust hood 22 large in the X direction. Therefore, in the optical fiber preform manufacturing apparatus 10 according to the present embodiment, even in the case of a long blank rod 14, the blank rod 14 is more uniform over the entire length in the longitudinal direction without increasing the size of the apparatus configuration. Glass particles can be deposited on the surface.

Furthermore, in the optical fiber preform manufacturing apparatus 10 according to the present embodiment, the movable range length L1, which is the length in the X direction of the movable range of the plurality of burners 20a, 20b, 20c, is the movable range length of the gripping parts 16a, 16b. It is set shorter than L0. By setting the movable range length L1 of the plurality of burners 20a, 20b, and 20c to be relatively short in this way, the exhaust mechanism including the exhaust hood 22 can more uniformly exhaust the plurality of burners 20a, 20b, and 20c. can be realized. On the other hand, since the movable range length L0 of the gripping parts 16a, 16b is set relatively long, even when the movable range length L1 of the plurality of burners 20a, 20b, 20c is set relatively short, the blank rod 14 Glass particles can be deposited over the entire length of the glass.

Furthermore, in this embodiment, various gases including flame gas and raw material gas are continuously supplied to each burner 20a, 20b, and 20c from the start to the end of manufacturing the optical fiber preform. As described above, in this embodiment, since the start and stop of supply of various gases is not repeated, various gases can be stably supplied to each burner 20a, 20b, and 20c, and various gases can be stably supplied to each burner 20a, 20b, and 20c. There is no need for waiting time until the gas supply becomes stable. Therefore, in this embodiment, the optical fiber preform can be manufactured with high efficiency.

Therefore, according to this embodiment, a high-quality optical fiber preform having a more uniform outer diameter over the entire length in the longitudinal direction of the blank rod 14 can be manufactured with high efficiency.

[Modified embodiment]
The present invention is not limited to the above embodiments, and various modifications are possible.

For example, in the above embodiment, the case where the optical fiber preform is manufactured by the OVD method has been described as an example, but the present invention is not limited to this. The optical fiber preform manufacturing method employed by the optical fiber preform manufacturing apparatus 10 may be, for example, an MCVD (Modified Chemical Vapor Deposition) method. In this case, instead of the blank rod 14, a tubular rod into which a raw material gas for forming glass particles is flowed is used, and burners 20a, 20b, and 20c are configured as burners for heating this tubular rod from the outside. be able to.

Further, in the embodiment described above, the case where the blank rod 14 is held by the holding parts 16a and 16b such that the central axis of the blank rod 14 is along the horizontal direction has been described as an example, but the present invention is not limited to this. The optical fiber preform manufacturing apparatus 10 may be configured, for example, so that the blank rod 14 is held by the holding parts 16a and 16b so that the central axis of the blank rod 14 is along the vertical direction.

10...Optical fiber preform manufacturing device 12...Device base 14...Blank rods 16a, 16b...Gripper 18...Burner stands 20a, 20b, 20c...Burner 22...Exhaust hood 24...Control device 110...Manufacture of optical fiber preform Device 210...Optical fiber preform manufacturing device

Claims (10)

a gripping part that rotatably grips the blank rod with the central axis of the blank rod as a rotation axis, and is movable in a movement direction along the central axis of the blank rod in a first movable range;
forming a flame for generating glass particles to be deposited on the blank rod, and movable in the moving direction from a fixed position in a second movable range whose length in the moving direction is shorter than the first movable range. multiple burners,
a control unit that controls the gripping unit and the plurality of burners;
The control unit is configured to rotate the blank rod with the grip, move the grip while stopping movement of the plurality of burners that formed the flame, and move the grip while stopping the movement of the plurality of burners that formed the flame, and rotate the blank rod while stopping the movement of the grip. An apparatus for manufacturing an optical fiber preform, characterized in that the plurality of burners formed with the above burners are moved. The optical fiber preform manufacturing apparatus according to claim 1, wherein the control section alternately repeats movement of the gripping section and movement of the plurality of burners. The control unit switches from moving the gripping unit to moving the plurality of burners when a positional relationship between one end of the blanking rod and the outermost burner on the one end side becomes a predetermined relationship. 3. The optical fiber preform manufacturing apparatus according to claim 2. The control unit controls the moving speed of the gripping portion and the plurality of burners so that relative speeds of the plurality of burners with respect to the blank rod are constant when moving the gripping portion and when moving the plurality of burners. The optical fiber preform manufacturing apparatus according to any one of claims 1 to 3, characterized in that the moving speed of the burner is controlled. The optical fiber preform manufacturing apparatus according to any one of claims 1 to 4, wherein the plurality of burners are installed so as to face the central axis of the blank rod. The optical fiber preform manufacturing apparatus according to any one of claims 1 to 5, wherein the plurality of burners are installed so as to be shifted in a direction intersecting the moving direction. The distance between the fixed position of one of the outermost burners and the fixed position of the other outermost burner in the moving direction of the plurality of burners is less than half the length of the blanking rod. The optical fiber preform manufacturing apparatus according to any one of claims 1 to 6, wherein the optical fiber preform is also small. The optical fiber preform manufacturing apparatus according to claim 1, wherein the width of the flame is smaller than the distance between the fixed positions of the burners adjacent to each other. The optical fiber preform according to any one of claims 1 to 8, further comprising an exhaust hood installed to face a region including the second movable range via the blank rod. Manufacturing equipment. a gripping part that rotatably grips the blank rod with the central axis of the blank rod as a rotation axis and is movable in a movement direction along the central axis of the blank rod in a first movable range; a plurality of burners that form a flame for generating glass particles and are movable in the movement direction from a fixed position in a second movement range whose length in the movement direction is shorter than the first movement range. A method for manufacturing an optical fiber preform using an optical fiber preform manufacturing device, the method comprising:
While rotating the blank rod by the gripping part, the gripping part is moved while stopping movement of the plurality of burners that have formed the flames, and the plurality of burners that have formed the flames while stopping movement of the gripping part. A method for manufacturing an optical fiber preform, characterized in that the glass particles are deposited on the blank rod by moving a burner.

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