JP2014009138A - Holding device of support road for optical fiber preform and method for manufacturing optical fiber preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a holding device holding a support rod for an optical fiber preform and an optical fiber preform capable of preventing swing and backlash of a starting material and capable of acquiring a favorable optical fiber preform free from eccentricity.SOLUTION: A holding device 1 has a chuck 2 in which an opening part 4 is provided, and a support rod 6 is retained in such a manner that when a tip part 61 of the support rod 6 is protruded from the opening part 4, a head part 62 is engaged with the bottom of the chuck 2. Also, it has a clamp 5 which presses the head part 62 of the support rod 6 retained in the chuck 2 against the bottom (the opening part 4 side) of the chuck 2. If the head part 62 of the support rod 6 is pressed on a reference surface 63 side by a press bar 51 of the clamp 5, the reference surface 63 of the support rod 6 is firmly fixed on the bottom of the chuck 2.

Description

  The present invention relates to a support rod gripping device used in a VAD method, an OVD method, or the like, and an optical fiber preform manufacturing method using the same.

Conventionally, as a method for manufacturing an optical fiber preform, a VAD method (Vapor phase axial deposition method), an OVD method (Outside Vapor deposition method), and the like are known. In the VAD method and the OVD method, a glass raw material containing silicon (for example, SiCl ₄ ) is introduced into a burner together with a combustion gas such as a flammable gas and an auxiliary combustion gas, and the glass raw material is subjected to a hydrolysis reaction or an oxidation reaction in a flame. In this method, glass fine particles are generated and deposited on a rotating rod (starting material) to form a glass fine particle deposit. In the OVD method, glass particles are deposited on the outer periphery of the rotating starting material, whereas in the VAD method, glass particles are deposited on the lower end of the starting material, and the starting material is gradually moved upward in the axial direction. Is the method.

  FIG. 11 is a cross-sectional view of the glass fine particle deposit manufacturing apparatus 100 used in the VAD method. As shown in FIG. 11, the glass particle deposit manufacturing apparatus 100 includes a starting material 108, a support bar 106 connected to the starting material 108, and a gripping device 101 that grips the support bar 106. Further, two burners 104 and 105 that generate glass particles arranged below the starting material 108, a reaction vessel 110 containing the starting material 108, the burners 104 and 105, the gripping device 101, and the like, and the reaction vessel 110 , And an exhaust pipe 111 disposed on the opposite side of the burners 104 and 105.

  The burners 104 and 105 are supplied with hydrogen gas, oxygen gas combustion gas, and glass raw materials such as silicon tetrachloride, and generate glass fine particles by a hydrolysis reaction. The generated glass particles adhere to and deposit on the lower end of the starting material 108, whereby a glass particle deposit is formed.

  The starting material 108 is supported by a support bar 106 connected to the starting material 108, and the upper end thereof is gripped by the gripping device 101. The gripping device 101 is connected to a rotation pulling device (not shown) by a main shaft 109.

  FIG. 12A is a diagram showing details of a conventional gripping device 101 used in the manufacturing apparatus 100 of FIG. The support rod 106 has a head 107 having a diameter larger than that of the tip. The gripping device 101 includes a chuck 102 having a substantially cylindrical shape and an opening 104 at the bottom, and grips the head 107 of the support bar 106 with the chuck 102. The diameter of the opening 104 is set smaller than the diameter of the head 107 of the support rod 106 and larger than the diameter of the tip. Further, the chuck 102 also has an opening on the side, so that the support bar 106 can be detached, and when the tip of the support bar 106 protrudes from the opening 104, the support bar 106 can be removed. A head 107 of 106 is locked around the opening 104 of the chuck 102, and the support rod 106 is gripped by the chuck 102.

  FIG. 12B is a diagram showing a conventional gripping device 101 b that is used in the manufacturing apparatus 100 of FIG. 11 and is different from the gripping device 101. In the gripping device 101b, an outer diameter of the support bar 106b is substantially constant, and one having a through hole 113 in the upper part is used. The gripping device 101b is provided with a chuck 102b having a substantially cylindrical shape and a through hole 112 in the lower part. By passing a pin 120 made of quartz or metal through the chuck 102b and the through holes 112 and 113 of the support bar 106b, the support bar 106b is provided. Grip.

  By the way, the gripping device 101 (101b) is axially rotated by an unillustrated rotary pulling device or the like. Further, it moves in the axial direction with the deposition of the glass fine particles on the starting material 108. A certain amount of clearance is generated in the chuck 102, the opening 104, the through holes 112 and 113, the pin 120, and the like in a state where the support rod 106 (106b) is accommodated. Therefore, there is a problem that when the shaft is rotated, rattling occurs or misalignment occurs, and the starting material 108 swings around. When the starting material 108 is swung around, the synthesized glass fine particle deposit is decentered from the center, which causes a problem of core decentering when used as an optical fiber preform.

  In addition, as a technique for suppressing such backlash and misalignment of the support rod, for example, in Patent Document 1, a conical protrusion is provided at the tip of one side of the support rod or the starting material, and a cone-like shape is provided at the tip of the other side. It is described that the central axis of the support bar and the central axis of the starting material are aligned by providing a concave portion and inserting and fixing the conical protrusion into the conical concave portion.

  Further, in Patent Document 2, the fitting portion at the tip of the support rod gripped by the chuck is formed into a pipe shape having a through hole passing through the central axis and orthogonal to the central axis, and a starting rod having a similar through hole is inserted. Then, a heat-resistant pin is passed through both through holes to support the weight of the starting rod and the glass base material to be synthesized. Then, a screw hole is provided in the two cross sections in the central axis direction across the through hole in the fitting portion, and a heat resistant screw is screwed through the screw hole to fix the starting rod. I have to.

  Further, in Patent Document 3, a holder hole is formed at the other end of the rotating pull-up bar, a starting rod for manufacturing an optical fiber preform is inserted into the holder hole, and the rotating pull-up bar and the starting bar are inserted. It is described that a starting rod is attached to a rotating pull-up bar through a bottle. Then, between the inner peripheral surface of the holder hole in which the starting bar is inserted and the outer peripheral surface of the starting bar, a glass fine particle-like paste is interposed to fix the starting bar to the holder hole.

  Further, Patent Document 4 discloses that in a gripping device that grips a dummy rod inserted inside a gripping claw member by rotating a tightening ring relative to a holder and advancing screwing, the fastening ring is elastically attached. It is described that a biasing means is provided to elastically bias the gripping claw member to the holder.

JP 2000-086269 A Japanese Patent Laid-Open No. 05-043255 JP-A-62-256735 JP 2008-178906 A

  However, when the structures of the above-mentioned Patent Documents 1 and 2 are used, wear is caused by using the support rod several times, and there is a possibility that rattling may occur. In addition, when the technique of Patent Document 3 is used, it is difficult to interpose a desired amount of paste-like glass fine particles, and the paste-like glass fine particles described above are used when used in the next step or the next rod. It is difficult to handle because it is difficult to remove completely. Moreover, since the structure of the gripping device described in Patent Document 4 is complicated, the cost increases.

  The present invention has been made in view of the above problems, and supports for an optical fiber preform that can prevent a starting material from swinging and rattling and obtain a good optical fiber preform without eccentricity. It is an object of the present invention to provide a gripping device for gripping a rod and a method for manufacturing an optical fiber preform.

In order to achieve the above-described object, a first invention is a gripping device for a support rod for an optical fiber preform, the chuck holding the support rod, and the head of the support rod held in the chuck. A clamp that presses the portion toward the opening of the chuck;
It is a holding device characterized by comprising.

  The support bar is firmly fixed to the chuck by pressing the head of the support bar with the clamp. By fixing the support bar to the chuck, it is possible to reduce backlash at the time of rotation and to suppress the swing of the starting material supported at the tip of the support bar. Thereby, an optical fiber preform without eccentricity can be manufactured.

  It is desirable that the clamp presses the head of the support rod through a pressing member made of an elastic material. Further, the support bar is firmly fixed to the chuck by the elastic force of the pressing member and the pressing force by the clamp.

  Further, the clamp includes a pressing bar that presses the head of the support bar and a moving mechanism that adjusts the position of the pressing bar. Since the pressing force can be adjusted by changing the position of the pressing bar by the moving mechanism, for example, the pressing force can be adjusted for each rod according to the degree of wear or chipping.

  The clamp may be a toggle clamp. A toggle clamp can apply a large load with a small force.

  The chuck is preferably made of metal. By making it metal, the strength of the chuck increases and it can withstand long-term use.

  It is desirable that the pressing load of the clamp be 0.5 kgf or more.

  Further, the support rod has a head having a diameter enlarged at a tip portion, and the chuck has an opening having a diameter smaller than the head of the support rod and larger than the tip portion of the support rod, It is desirable to hold the support bar so that the head is locked around the opening when the tip of the support bar is passed through the opening to the outside.

  In a second aspect of the invention, the gripping device of the first invention is detached from the optical fiber preform manufacturing apparatus, the gripping device grips the support bar, and the support bar and the starting material are connected, and Attaching the gripping device to the optical fiber preform manufacturing apparatus while gripping the support rod with the starting material connected to the gripping device. .

  According to the second invention, the gripping device grips the support rod and connects the support rod and the starting material, and then the gripping device is attached to the optical fiber preform manufacturing apparatus, so that the frequency of occurrence of core bending is small and the bending is performed. The amount can be reduced on average.

  In addition, it is preferable that the method further includes a step of measuring a whirling of a tip portion of the starting material after connecting the support bar and the starting material. Thereby, the optical glass base material without eccentricity can be manufactured.

  According to the present invention, a gripping device for gripping a support rod for an optical fiber preform and an optical device capable of preventing a whirling and rattling of the starting material and obtaining a good optical fiber preform with suppressed eccentricity. A method for manufacturing a fiber preform can be provided.

The figure which shows the holding | grip apparatus 1 for the optical fiber preform | base_material support rod which concerns on this invention. The figure explaining the process and inspection process which connect a support bar and a starting material. The figure which shows the manufacturing apparatus 90 of the glass fine particle deposit body used by VAD method. The figure which shows the holding | grip apparatus 1a for optical fiber preform | base_material support bars which concerns on this invention. The figure which shows the holding | grip apparatus 1b for optical fiber preform | base_material support bars which concerns on this invention. The figure which shows the state which fixed the support rod with the toggle clamp 8 in the holding | grip apparatus 1b. The figure which shows the holding | grip apparatus 1c for optical fiber preform | base_material support bars which concerns on this invention. The graph which shows the frequency of occurrence of core bending in the state where there is no press. The graph which shows the frequency of occurrence of core bending when a clamp is used. The graph which shows the generation | occurrence | production frequency of the core bending at the time of using the holding | grip apparatus of this invention from the connection of a support bar and a starting material in the manufacturing process of an optical fiber preform | base_material. The figure which shows the manufacturing apparatus 100 of the conventional glass fine particle deposit body used by VAD method. (A) is a figure which shows the detail of the conventional holding | grip apparatus 101 part used with the manufacturing apparatus 100 of FIG. 11, (b) is a figure which shows the detail of the other holding | gripping apparatus 101b.

  Hereinafter, a gripping device 1 for an optical fiber preform support rod according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of the gripping device 1. The gripping device 1 mainly includes a chuck 2, a clamp 5, a support bar 6, a support bar pressing member 3, and the like.

  The support rod 6 is a rod that supports the starting material and the like of the glass fine particle deposit, and the head 62 has a diameter larger than that of the rod-like portion (hereinafter referred to as the tip portion 61). In the example of FIG. 1, the head 62 of the support bar 6 has a cylindrical shape, and the upper surface and the bottom surface are perpendicular to the axis of the support bar 6. In the following description, the bottom surface of the head 62 of the support bar 6 is referred to as a reference surface 63. The support bar 6 is gripped by the chuck 2 so that the reference surface 63 is orthogonal to the main shaft 9. Moreover, the front-end | tip part 61 of the support bar 6 protrudes from the opening part 4 of the chuck | zipper 2, and is connected with the starting material (not shown) in the front-end | tip. The starting material is a target on which glass particulates are deposited.

The chuck 2 is a substantially cylindrical member having an opening 4 at the bottom when the main shaft 9 side is at the top, and holds the support bar 6. The diameter of the opening 4 is set smaller than the diameter of the head 62 of the support bar 6 and larger than the diameter of the tip 61 of the support bar 6. Since the head 62 of the support rod 6 has a diameter larger than that of the tip 61, the head 62 of the support rod 6 is accommodated inside the chuck 2, and the tip 61 of the support rod 6 protrudes from the opening 4. At this time, the head 62 of the support bar 6 is locked around the opening 4 of the chuck 2. It is desirable that a fitting portion 22 for fitting the head 62 of the support rod 6 is provided on the inner wall of the bottom of the chuck 2. The diameter of the fitting portion 22 is set so as to substantially match the diameter of the head 62 of the support rod 6.
The chuck 2 also has an opening (not shown) on the side, and the support bar 6 can be detached from the opening on the side.

  The clamp 5 has a pressing bar 51 and a moving mechanism for the pressing bar 51. The moving mechanism includes a pair of rotating bodies 52, a ring 53 fixed to one of the rotating bodies 52, a lever 54, and the like. The presser bar 51 is provided in parallel with the reference surface 63 of the support bar 6, and both ends thereof are connected to and supported by the pair of rotating bodies 52. The rotating body 52 is passed through through holes provided at positions facing each other on the side wall of the chuck 2, and one of the pair of rotating bodies 52 protrudes outside the chuck 2 and is fitted into the ring 53. The ring 53 is provided with a lever 54. When the ring 53 is rotated using the lever 54, the rotating body 52 can be rotated. The presser bar 51 is provided at a position offset from the rotation center of the rotating body 52. When the rotating body 52 is rotated using the lever 54, the presser bar 51 moves in the axial direction of the support bar 6, thereby supporting the support bar. The pressing member 3 is pressed in the direction of arrow A in FIG.

  Thus, since the clamp 5 has the moving mechanism of the pressing bar 51 and the pressing bar 51, the pressing force can be adjusted by adjusting the position of the pressing bar. Therefore, for example, the pressing force can be adjusted for each rod to be gripped according to the degree of wear or chipping of each support rod.

  The support bar pressing member 3 is interposed between the press bar 51 of the clamp 5 and the head 62 of the support bar 6. The support bar pressing member 3 is preferably formed of an elastic material such as a fluorinated resin. The shape of the support bar pressing member 3 is preferably a cylindrical shape whose upper surface and bottom surface are parallel, for example. The support bar pressing member 3 is elastically deformed by the pressing force of the clamp 5, and the head 62 (reference surface 63) of the support bar 6 is pressed against the bottom of the chuck 2 by the elastic force. Thereby, the support bar 6 is more firmly fixed to the chuck 2.

  The chuck 2 and the clamp 5 are preferably made of a metal material. By making it metal, the strength of the chuck increases and it can withstand long-term use. The chuck 2 is preferably made of, for example, titanium or nickel in consideration of heat resistance, durability, corrosion resistance, and the like, but may be made of other metals. In particular, the chuck 2 is often made of glass, but by using a metal, wear due to rotation, chipping around the opening 4 and distortion can be reduced.

  Next, an optical fiber preform manufacturing method using the gripping device 1 will be described. The gripping device 1 shown in FIG. 1 is configured to be detachable from the optical fiber preform manufacturing apparatus. First, the support bar 6 is gripped by the chuck 2 of the gripping device 1 with the gripping device 1 removed from the optical fiber preform manufacturing apparatus. In this state, the support rod 6 and the starting material 7 are connected, and the holding device 6 connected to the starting material 7 is held by the holding device 1 while the holding device 1 is held by an optical fiber preform manufacturing apparatus (for example, FIG. 2 (c) and the glass fine particle deposit manufacturing apparatus 90 shown in FIG.

  FIG. 2 is a diagram for explaining the connecting step between the support bar 6 and the starting material 7 and the run-out inspection step of the starting material 7. This connection step and inspection step are performed before the step of depositing glass particles on the starting material 7. As described above, the gripping device 1 is first removed from the optical fiber preform manufacturing apparatus such as the glass particulate deposit manufacturing apparatus 90 and attached to the starting material connecting apparatus 70 shown in FIG.

  The starting material connecting device 70 has a gripping portion 72 that grips the gripping device 1 in the upper portion and a support portion 73 that supports the starting material 7 in the lower portion. For example, the main shaft 9 of the gripping device 1 is attached to the gripping portion 72. Further, the support bar 6 held by the chuck 2 of the holding device 1 is pressed and fixed by a clamp 5. The tip end of the support bar 6 gripped by the gripping device 1 and the tip end of the starting material 7 supported by the support portion 73 are aligned so that the center axis is aligned, and in this state, are bonded by the burner 74.

  When the starting material 7 is connected to the support rod 6, as shown in FIG. 2 (b), the holding device 1 is removed from the starting material connecting device 70 and connected to the inspection device 77 shown in FIG. 2 (c). The The inspection device 77 is a device that inspects the shake of the starting material 7. The inspection device 77 is provided with a gripping portion 791 for gripping the starting material 7a connected to the support rod 6 gripped by the gripping device 1, a rotating device 79 for rotating the support rod 6 and a shake measuring device 78. It has been. The shake measuring device 78 is provided at the tip position of the starting material 7 in a state where the gripping device 1 is gripped by the gripping portion 791, and the swinging magnitude of the tip of the starting material 7 when the support rod 6 is rotated about the axis is provided. Measure. In the run-out inspection of the starting material 7 by the inspection device 77, the passed starting material 7 a (starting material 7 connected to the support bar 6) whose swing size is a predetermined value or less is transferred from the inspection device 77 to the gripping device 1. After being removed, the process proceeds to the next step (step of depositing glass fine particles on the starting material 7). In addition, what was rejected is adjusted so that the swivel of the tip of the starting material 7 becomes small by heating and softening the connecting portion of the support rod 6 and the starting material 7 again using the starting material connecting device 70. After that, the shake measurement can be performed again.

  FIG. 3 is a cross-sectional view of a glass fine particle deposit manufacturing apparatus 90 used in the VAD method. As shown in FIG. 3, the glass fine particle deposit manufacturing apparatus 90 includes a starting material 7, a support bar 6 to which the starting material 7 is connected, and a gripping device 1 that grips the support bar 6. Further, the glass fine particle deposit manufacturing apparatus 90 includes two burners 94 and 95 for generating glass fine particles arranged below the starting material 7, the starting material 7, the burners 94 and 95, the gripping device 1, and the like. A reaction vessel 91 and an exhaust pipe 92 disposed on the opposite side of the reaction vessel 91 from the burners 94 and 95.

  Glass materials such as hydrogen gas, oxygen gas combustion gas and silicon tetrachloride are supplied to the burners 94 and 95, and glass fine particles are generated by a hydrolysis reaction. The generated glass fine particles adhere to and deposit on the lower end of the starting material 7, thereby forming a glass fine particle deposit.

  The burner 94 is a core burner for forming a core portion located at the center, and the burner 95 is a clad burner for forming a clad portion located on the outer periphery of the core portion. The core burner 94 is supplied with germanium tetrachloride gas, which is a dopant material gas for controlling the refractive index, in addition to silicon tetrachloride gas, which is a glass material gas.

  The step of forming the glass fine particle deposit is performed in the reaction vessel 91, and the gas in the reaction vessel 91 and the glass fine particles not attached to the starting material 7 are sucked from the exhaust pipe 92 by a suction device (not shown). Exhausted.

  The starting material 7 is connected to the support bar 6, and the upper end of the support bar 6 is gripped by the gripping device 1. The gripping device 1 is connected to a rotation pulling device (not shown) by a main shaft 9.

  The gripping device 1 is rotated by an unillustrated rotary pulling device or the like. Further, it moves in the axial direction as the glass fine particles are deposited on the starting material 7. If the gripping device 1 of the present invention is used, the support bar 6 is firmly fixed to the chuck 2 by the clamp 5, so that rattling and misalignment are less likely to occur when the shaft is rotated. Therefore, the shake of the starting material 7 is reduced, and the eccentricity of the glass fine particle deposit can be suppressed. In addition, as described above, if the support bar 6 is pressed and fixed using the gripping device 1 from the step of connecting the starting material 7 to the support bar 6, the swinging of the starting material 7 can be further suppressed.

  As described above, the gripping device 1 according to the embodiment of the present invention has the chuck 2 provided with the opening 4, and the head 62 when the tip 61 of the support bar 6 protrudes from the opening 4. Holds the support bar 6 so as to engage with the bottom of the chuck 2. In addition, a clamp 5 is provided that presses the head 62 of the support rod 6 held in the chuck 2 against the bottom (opening 4 side) of the chuck 2. The clamp 5 includes a pressing bar 51 provided in parallel to the reference surface 63 of the support bar 6 and a moving mechanism (rotating body 52, ring 53, and lever 54) that moves the pressing bar 51. The pressing force can be adjusted by changing. In this manner, when the head 62 of the support bar 6 is pressed toward the reference surface 63 by the pressing bar 51 of the clamp 5, the reference surface 63 of the support bar 6 is firmly fixed to the bottom of the chuck 2.

  Note that the pressing force of the clamp is desirably 0.5 kgf or more. By doing in this way, the head 62 of the support bar 6 can be fixed reliably. Note that the upper limit of the clamp pressing load may be a load that is lower than the compressive strength of the head 62, for example.

  Further, by interposing the support bar pressing member 3 made of an elastic material between the pressing bar 51 of the clamp 5 and the head 62 of the support bar 6, the elastic force of the support bar pressing member 3 and the pressing force by the clamp 5 can be reduced. Thus, the reference surface 63 of the support bar 6 is firmly fixed to the bottom of the chuck 2.

  In this way, by firmly fixing the reference surface 63 of the head 62 of the support bar 6 so as not to be displaced from the bottom of the chuck 2, the starting material supported at the tip of the support bar 6 is reduced. Can suppress the swinging of. Thereby, an optical fiber preform without eccentricity can be manufactured.

  Further, by providing a fitting portion 22 having substantially the same diameter as the head 62 of the support bar 6 on the inner wall of the bottom of the chuck 2, misalignment between the main shaft 9 of the chuck 2 and the support bar 6 is prevented, and eccentricity during rotation is achieved. Can be eliminated.

  Further, by making the chuck 2 made of metal, it is possible to prevent chipping and wear as compared with the case where a conventional glass chuck is used, and it can withstand long-term use.

  In the gripping device 1 in FIG. 1, the example in which the support bar 6 has different diameters for the tip 61 and the head 62 has been described. However, the support bar 6 is gripped with other shapes. It is also effective in some cases. FIG. 4 is a diagram illustrating a gripping device 1 a that grips the support rod 6 having the tapered portion 65 between the tip portion 61 and the head portion 62. In the gripping device 1a in FIG. 4, the same parts as those in the gripping device 1 in FIG.

  As shown in FIG. 4, the gripping device 1 a is provided with a taper portion 65 on the support bar 6 as compared with the gripping device 1 shown in FIG. 1. The taper portion 65 of the support rod 6 gradually increases in diameter from the tip portion 61 toward the head portion 62. The head 62 and the tapered portion 65 have different diameters at the boundary.

  Further, the opening 4 a provided at the bottom of the chuck 2 a is also provided with an inclination that matches the shape of the tapered portion 65 of the support rod 6. That is, the opening 4a is gradually reduced in diameter from the inside (upper side) to the outside (lower side) of the chuck 2a. Thereby, the chuck 2 and the support rod 6 can be easily and accurately aligned.

  The clamp 5 is the same as in FIG. 1, and by tightening the lever 54, the position of the pressing bar 51 can be moved, and the pressing force in the direction of arrow A in FIG. 4 can be adjusted.

  According to the gripping device 1a shown in FIG. 4, the head 62 of the support bar 6 is fitted and supported by the fitting portion 22 provided at the bottom of the chuck 2, as in the gripping device 1 of FIG. Since it is supported by the inclination of the bottom side surface of the chuck 2, misalignment and backlash can be further reduced as compared with the gripping device 1 of FIG. 1. This makes it possible to prevent the starting material supported by the support bar 6 from swinging.

  Furthermore, the clamp 5 is not limited to that shown in FIGS. 1 and 4, and other types of clamps may be used. 5 and 6 are views showing a gripping device 1b using a toggle clamp 8 in place of the clamp 5 in the gripping device 1 of FIG. FIG. 5 shows a state in which the toggle clamp 8 is loosened, and FIG. 6 shows a state in which the toggle clamp 8 is tightened.

  As shown in FIGS. 5 and 6, the toggle clamp 8 is fixed to the side wall of the chuck 2 by a fixing tool 87. The toggle clamp 8 includes a first link 81 whose one end is pivotally supported by the fixture 87, a second link 82 whose one end is pivotally fixed to the other end of the first link 81, and the other end of the second link 82. And an L-shaped third link 83 whose corners are axially fixed. One end of the third link 83 is fixed to the fixture 87. A pressing portion 84 is provided at the other end of the third link 83. A plate spring 85 is provided on the holding portion 84, and the plate spring 85 presses the head of the support bar 6 when the toggle clamp 8 is tightened as shown in FIG. 6.

  The first link 81, the second link 82, and the third link 83 of the toggle clamp 8 rotate with respect to each other at the above-described shaft stopping points. The second link 82 has a lever 86, and the angle of the second link 82 is adjusted by the lever 86.

  When the lever 86 is moved downward and the angle between the first link 81 and the second link 82 approaches 180 degrees, as shown in FIG. The corners of the three links 83 are moved inward of the chuck 2. Along with this, the third link 83 rotates around the axial stop point with the fixture 87, the pressing portion 84 moves, and the head 62 of the support bar 6 is pressed. As a result, the reference surface of the support bar 6 is firmly fixed to the bottom of the chuck 2.

  Further, since the leaf spring 85 is provided on the pressing portion 84 of the toggle clamp 8, the pressing force can be increased by the elastic biasing force of the leaf spring 85. Further, instead of the leaf spring 85, a support bar pressing member 3 as shown in FIG. 1 may be interposed between the pressing portion 84 and the support bar.

  As shown in FIGS. 5 and 6, by using the toggle clamp 8, a large pressing load can be applied with a small force.

  In the above-described embodiment, the support rod 6 having an enlarged head 62 is used, and the grip 62 has a structure in which the head 62 of the support rod 6 is locked and held around the opening 4 of the chuck 2. Although the apparatus has been described, the shapes of the support bar 6 and the chuck 2 and the holding structure are not limited thereto. For example, as shown in FIG. 7, a support rod 6c having a substantially constant outer diameter and having a through hole 13 at the top may be used. In this case, the gripping device 1c is provided with a chuck 2c having a substantially cylindrical shape and having a through-hole 12 in the lower portion, and is supported by passing pins 20 made of quartz or metal through the through-holes 12 and 13 of the chuck 2c and the support rod 6c. Hold the rod 6c. In such a gripping device 1c configured to grip the support bar 6c using the pin 20, the head of the support bar 6c may be pressed by the clamp 5 similarly to the gripping device 1 of FIG. Further, the head of the support bar 6c may be pressed by the clamp 5 through the support bar pressing member 3 made of an elastic material. Further, in the gripping device 1c of FIG. 7, a toggle clamp 8 shown in FIGS. 5 and 6 may be used instead of the clamp 5.

  Using a conventional gripping device 101 (FIG. 12) that is not pressed by a clamp and the gripping device 1 (FIG. 1) according to the present invention, a glass particle deposit is produced in the same manner, and the occurrence of core bending occurs. The frequency was examined. FIG. 8 is a graph showing the frequency of occurrence of core bending when the conventional gripping device 101 (FIG. 12) that is not pressed by a clamp is used. FIG. 9 is a graph showing the frequency of occurrence of core bending when the holding device 1 according to the present invention is used and the support bar 6 is pressed and fixed by a clamp. The pressing load by the clamp was 0.7 [kgf]. In each case, 51 optical fiber preforms are to be measured.

Here, the core bending is a value measured as follows.
First, the produced glass particulate deposit is vitrified by placing it in a high temperature furnace. The vitrified core is set on a chuck of a core bending measuring device prepared separately from the glass fine particle deposit manufacturing apparatus.
The core bending measuring device can grip the distal end portion of the support rod so as to be rotatable about the central axis of the core. Note that the gripping device of the core bending measuring device can be the same as the above-described glass particle deposit manufacturing device.

  Next, the vitrified core set in the core bending measuring device is rotated around the center axis of the core, and the swing width at the position corresponding to the tip of the seed bar and the swing width at the tip of the core Measure. From the obtained measurement result, (swinging width at the tip of the core−swinging width at the position corresponding to the tip of the seed rod) / 2 was calculated to be the core bending.

  When the support rod 6 is not pressed by the clamp as in the conventional case, the occurrence frequency of the core bending is large from 1.1 [mm] to 1.6 [mm] as shown in FIG. 8, and the average is 1.22 [mm]. A core bend occurred. The maximum value of the core bending is as large as 2 [mm], and the standard deviation is 0.29.

  On the other hand, when the pressing load by the clamp is 0.7 [kgf], as shown in FIG. 9, the frequency of occurrence of the core bending is large in the vicinity of 0.5 [mm] to 1.0 [mm], and the average is 0. .80 [mm] core bending occurred. The maximum value of the core bending is 1.3 [mm] and the standard deviation is 0.23.

  As described above, when the support rod 6 is pressed using the clamp, the frequency of occurrence of the core bending is lower and the amount of the bending is smaller and the variation is smaller than the case where there is no pressing by the clamp. Got.

  Further, the gripping device 1 according to the present invention is configured to be removable from the optical fiber manufacturing apparatus, and the gripping device 1 according to the present invention grips from the step of connecting the support bar 6 and the starting material 7 as shown in FIG. It is preferable to do so.

  FIG. 10 shows a configuration in which the gripping device 1 according to the present invention is detachable from the optical fiber manufacturing apparatus, and the support rod 6 is gripped by the gripping device 1 in a state of being detached from the optical fiber manufacturing device. 7 is a graph showing the frequency of occurrence of core bending when the core synthesizing process is performed by attaching the gripping device 1 to the optical fiber manufacturing apparatus while gripping the support rod 6 in which the starting material 7 is connected to the gripping device 1. It is.

In addition, after connecting the support bar 6 and the starting material 7, the process of rotating the holding | grip apparatus 1 and measuring the whirling of the rotating shaft of the starting material 7, and the process of aligning the center axis | shaft of the supporting bar 6 and the starting material 7 further It is preferable to further have.
By doing so, the center axis of the support bar 6 and the starting material 7 can be more aligned, and the center axis is aligned and installed in the manufacturing apparatus without removing the support bar 6 from the gripping device 1. As a result, it is possible to maintain a state where the central axes of the support rod 6 and the starting material 7 are aligned.
The pressing load by the clamp was 0.6 [kgf]. The measurement target is 52 optical fiber preforms.

  In this case, as shown in FIG. 10, the frequency of occurrence of core bending is high in the vicinity of 0.5 [mm] to 0.8 [mm], and an average core bending of 0.60 [mm] occurred. The maximum value of the core bending is 1.1 [mm] and the standard deviation is 0.18.

  As described above, when the gripping device 1 of the present invention is used in common from the process of connecting the support rod 6 and the starting material 7, the occurrence frequency of the core bending is small, and the bending amount is also small on average, resulting in variations. Also obtained a smaller result.

  As described above, the gripping device of the present invention grips the head of the support bar so that the head of the support bar is locked to the bottom of the chuck when the tip of the support bar passes from the bottom opening of the chuck to the outside. By pressing the head of the support rod with the clamp, the reference surface of the support rod is firmly fixed to the bottom, and it is possible to prevent the starting material from swinging and to obtain a good optical fiber preform without eccentricity. Become. Thereby, the productivity of the optical fiber preform can be increased.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. For example, the gripping devices 1, 1 a, 1 b, and 1 c shown in FIGS. 1 to 7 are vertical manufacturing apparatuses in which the glass particulate deposits are held vertically, but are horizontal types that hold the glass particulate deposits in the lateral direction. You may make it use for this manufacturing apparatus. In addition, it is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the scope of claims. It is understood that it belongs to the range.

1, 1 a, 1 b, 1 c... Gripping device 12, 13... Through-hole 2, 2 c. ......... Opening 5 ......... Clamp 51 ......... Presser bar 52 ......... Rotating body 53 ......... Ring 54 ...... Lever 6 ......... Support bar 61 ...... Support bar tip 62 ......... Support rod head 63 ......... Reference surface 65 ......... Tapered portion 7 ... Starting material 70 ...... Starting material connecting device 77 ...... Inspection device 78 ...... Runout measuring device 79 ......... Rotation drive device 8 ......... Toggle clamp 81 ......... First link 82 ......... Second link 83 ......... Third link 84 ......... Pressing portion 85 ......... Plate spring 86 ......... Lever 9 ......... Main shaft 90 ... …… Production apparatus 91 for glass particulate deposits ... …… Reaction vessel 92 ………… Exhaust pipes 94, 95 ……… Burner

Claims (9)

A holding device for a support rod for an optical fiber preform,
A chuck for holding the support rod;
A clamp that presses the head of the support rod held in the chuck toward the opening of the chuck;
A gripping device comprising:   The gripping device according to claim 1, wherein the clamp presses the head of the support rod through a pressing member made of an elastic material.   The gripping device according to claim 1, wherein the clamp includes a pressing bar that presses the head of the support bar, and a moving mechanism that adjusts the position of the pressing bar.   The gripping device according to claim 1 or 2, wherein the clamp is a toggle clamp.   The gripping device according to any one of claims 1 to 4, wherein the chuck is made of metal.   The gripping device according to any one of claims 1 to 5, wherein a pressing load of the clamp is 0.5 kgf or more. The support rod has a head that has an enlarged diameter at the tip,
The chuck has an opening having a diameter smaller than that of the head of the support rod and larger than the tip of the support rod, and the head when the tip of the support rod is passed through the opening to the outside. The gripping device according to any one of claims 1 to 6, wherein the support rod is held so that a portion is locked around the opening. A step of causing the gripping device to grip a support bar and connecting the support bar and the starting material in a state where the gripping device according to any one of claims 1 to 7 is detached from the optical fiber preform manufacturing apparatus. ,
Attaching the gripping device to the optical fiber preform manufacturing apparatus while gripping the support rod to which the starting material is connected to the gripping device;
An optical fiber preform manufacturing method comprising:   9. The method of manufacturing an optical fiber preform according to claim 8, further comprising a step of measuring a whirling of a tip portion of the starting material after connecting the support bar and the starting material.

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