JPH04350811A - Method and apparatus for producing metal pipe covered optical fiber cable - Google Patents

Abstract

PURPOSE:To prevent the dust remaining in an introducing pipe and to surely protect the introducing pipe and an optical fiber, etc., against the weld heat in a metallic pipe so as to assure the operation stable over a long period of time. CONSTITUTION:While the optical fiber 2 and gas or packing material are fed into the metallic pipe 10 by the introducing pipe 6 inserted into the metallic pipe 10, a part of the gas and the packing material are allowed to flow over from the inlet of a guide pipe 3 for guiding the optical fiber, by which the dust sticking to the surface of the optical fiber 2 is purged from the inlet of the guide pipe 3. This introducing pipe 6 is brought into elastic pressurized contact with the inside wall of the metallic pipe 10 on the side opposite from the face of weld 17 in the weld zone of the metallic pipe 10, by which the introducing pipe 6 is brought to the side opposite from the face of weld at all times even if vibrations, etc., are generated in the metallic pipe transported continuously.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a manufacturing method and manufacturing apparatus for continuously manufacturing metal tube-coated optical fiber cables,
In particular, it relates to the removal of dust and the like attached to optical fiber cables.

0002

2. Description of the Related Art In order to ensure the installation tension and water resistance of optical fiber cables, metal tube-covered optical fiber cables, which are optical fiber cables covered with thin metal tubes, are used. Apparatuses for continuously manufacturing this metal tube coated optical fiber cable are disclosed in, for example, Japanese Patent Laid-Open No. 58-95304 and Japanese Patent Laid-Open No. 57-100402. Metal-coated fiber optic cable manufacturing equipment forms a continuously fed flat metal strip into a metal tube with a longitudinal gap at the top. An introduction tube is inserted into the metal tube through the gap in the metal tube, and the optical fiber is introduced into the metal tube using the introduction tube. After closing the gap between the metal tubes into which this optical fiber has been introduced, the feed butt portions are welded using a laser welding device or the like. Thereafter, the outer diameter of the metal tube containing the optical fiber cable is reduced to a predetermined size, and then wound around a capstan and continuously pulled out to produce a metal tube-covered optical fiber cable. When manufacturing a metal tube-covered optical fiber cable in this manner, the introduction tube is extended downstream from the welding part to prevent the heat of welding from damaging the optical fiber.

[0003] The optical fiber used in this metal tube coated optical fiber cable usually has a core wire coated with an ultraviolet curable resin, which tends to generate static electricity, and thus tends to attract dust in the air. If the optical fiber to which this dust has adhered is passed through the introduction tube as it is, the dust will remain in the introduction tube during long-term operation, giving the optical fiber an extra backward tension. In particular, when a metal tube is filled with a viscous substance such as gel, dust adhering to the optical fiber is likely to mix with the gel and adhere to and accumulate on the wall of the introduction tube. For this reason, in order to control the extra length of the optical fiber, the tension of the optical fiber adjusted before inserting the introduction tube fluctuates, making it impossible to control the extra length of the optical fiber. It was difficult to manufacture.

In order to solve this problem, a method of manufacturing a metal tube coated optical fiber cable in a clean room has been proposed, for example, in Japanese Patent Laid-Open No. 57-123838 (Japanese Patent Publication No. 59-3414). Disclosed. In this method, an optical fiber core wire drawn in a vacuum atmosphere is coated with a primary coating in that atmosphere, and then the optical fiber is immediately introduced into a metal tube in a vacuum atmosphere and the metal tube is welded to form an optical fiber. Prevents dust from adhering.

[0005]

[Problem to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 1983-1995
As shown in Publication No. 304, etc., when an optical fiber is introduced by simply inserting an introduction tube into a metal tube, no major problem arises when the butt part at the bottom of the metal tube is joined by brazing. , the butt part at the top of the metal tube is TI
When welding and sealing metal tubes using G welding or laser welding, welding spatter accumulates on the inlet tube, and if the operation is continued for a long time, the accumulated welding spatter may come into contact with the inner wall of the metal tube, causing welding defects. was there. For this reason, especially 5km
There is a disadvantage in that it is not possible to continuously manufacture metal tube coated optical fibers as long as above.

[0006] Furthermore, since the introduction pipe is only inserted into the metal pipe without any particular positioning, vibrations of the metal pipe during running may sometimes cause the gap between the introduction pipe and the welded surface of the metal pipe to become very small. turn into. At times like this, T.I.
The heat of G welding and laser welding causes burnout and holes in the upper surface of the introduction tube, which poses a risk of thermal damage to the optical fiber passing through the interior and of the gel burning.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 57-123838, a method of manufacturing a metal tube-coated optical fiber cable in a clean room prevents dust in the air from adhering to the optical fiber. It is possible to prevent this. However, during the metal tube forming process, ducts are formed from the brush of the motor of the drive mechanism and adhere to the optical fiber, and this dust gets mixed into the gel and adheres to and accumulates on the wall of the introduction tube. stay in the jurisdiction for a long time. Since the dust remaining inside the introduction tube cannot be removed, extra backward tension is applied to the optical fiber, and the tension is adjusted to adjust the length of the optical fiber relative to the length of the extra length, that is, the length of the metal tube. In the case of controlling by , it is difficult to uniformly manufacture products of the same quality, especially long products.

[0008] This disadvantage can be overcome by blocking only the path of the optical fiber with a clean gas curtain, but the opening at the boundary with the metal tube forming equipment is large and outside air is drawn in, causing dust to enter the optical fiber. It was difficult to completely prevent the adhesion. Further, due to the curtain structure, each time the metal tube forming device is adjusted, airflow is disturbed, making it easy for dust to adhere to the optical fiber, and the adjustment work of the forming device is also hindered.

The present invention has been made to solve these shortcomings, and is intended to prevent dust from remaining in the introduction tube and to reliably protect the introduction tube and optical fibers from the heat of welding the metal tube. The object of the present invention is to provide a method and apparatus for manufacturing a metal tube-coated optical fiber that can be stably operated for a long period of time.

0010

[Means for Solving the Problems] A method for manufacturing a metal tube-coated optical fiber according to the present invention involves forming a continuously fed metal strip, and welding the abutted portions to form an optical fiber or optical fiber in a metal tube. In a method for manufacturing a metal tube-coated optical fiber in which a bundle is introduced into the metal tube, the fiber is connected to a guide tube that guides the optical fiber or the optical fiber bundle and a supply tube that supplies either one or both of a gas and a filler. Guide a part of the gas and/or filling into the optical fiber or optical fiber bundle while feeding the optical fiber or the optical fiber bundle and/or the gas or the filling into the metal tube with the inserted introduction tube. It is characterized by overflowing from the entrance of the guide tube.

[0011] It is preferable to use an inert gas or a cooling gas as the above gas. It is also preferable to use a waterproof material as the filler.

[0012] Furthermore, the apparatus for manufacturing a metal tube-coated optical fiber according to the present invention molds a continuously fed metal strip and welds the abutting portions to form a metal tube, and introduces an optical fiber or an optical fiber bundle into the metal tube. A metal tube-coated optical fiber manufacturing device includes a guide tube that guides an optical fiber or optical fiber bundle, a supply tube that supplies gas and/or a filler, and a supply tube that is inserted into the metal tube and that guides the optical fiber or optical fiber bundle. A fiber bundle, an introduction pipe that sends either one or both of the gas and the filling material into the metal tube, and a part of the gas and/or the filling material that connects the guide pipe, the supply pipe, and the introduction pipe, and is sent from the supply pipe. and a connecting portion that sends the optical fiber in the direction opposite to the traveling direction of the optical fiber or the optical fiber bundle of the guide tube.

[0013] It is preferable that the introduction pipe is elastically pressed against the inner wall of the metal tube on the side opposite to the welding surface at the welded portion of the metal tube.

[0014]

[Operation] In this invention, an optical fiber or an optical fiber bundle and one or both of the gas and the filling material are fed into the metal tube by the introduction tube inserted into the metal tube. By overflowing from the entrance of the guide tube that guides the optical fiber or optical fiber bundle, dust adhering to the surface of the optical fiber or optical fiber bundle is purged from the entrance of the guide tube.

At the welding part of the metal tube, this introduction tube is inserted and fixed so that it comes into elastic pressure contact with the inner wall of the metal tube on the opposite side to the welding surface, and the metal tube is fed while being continuously formed. Always position the inlet pipe on the opposite side of the welding surface even if vibrations occur.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the present invention. As shown in the figure, the optical fiber introducing device 1 includes a guide tube 3 for guiding an optical fiber or an optical fiber bundle (hereinafter referred to as an optical fiber) 2, a supply tube 5 for supplying a cooling gas 4, and a straight tube. It has a molded introduction pipe 6, a guide pipe 3, and an introduction pipe connecting fitting 7 that connects the supply pipe 5 and the introduction pipe 6. The communication hole 8 of this introduction pipe connecting fitting 7 with the guide pipe 3 is connected to the introduction pipe 6.
The inner diameter is narrower than that of the communicating hole 9. The introduction tube 6 is made of copper or a copper alloy with good thermal conductivity, and is inserted into a metal tube 10 that covers the optical fiber 2.

The metal tube 10 is formed by molding a continuously fed metal strip 10a. That is, the metal strip 10a fed through the pinch rolls 11 is formed into a substantially U-shape by the breakdown forming rolls 12 disposed at an angle while rising from below, and the metal strip 10a is formed into a substantially U-shape by the guide rolls 1.
3 to a forming roll 14. The metal tube 10 is formed by abutting both ends of the substantially U-shaped metal strip 10b with a forming roll 14 and welding the abutted portion with a laser welding device 15. The introduction pipe 6 is inserted at the position of the almost U-shaped metal strip 10b, and a downward pressing force is applied to the introduction pipe 6 by the pressure mechanism 16, so that the introduction pipe 6 is placed near the position of the laser welding device 15. Then, it is pressed and fixed to the inner wall of the metal tube 10 on the side opposite to the welding surface 17.

Metal tube 10 that is continuously fed as described above
2, the tension of the optical fiber 2 is adjusted by the dancer roll 21 provided at the front stage of the optical fiber introduction device 1, and the tension of the optical fiber 2 is adjusted. is sent to the metal tube 10 while being guided by the guide tube 3 and introduction tube 6. At the same time, cooling gas 4 is continuously supplied from the supply pipe 4 at a constant pressure. Then, the abutting portions of the metal tubes 10 are welded using a laser welding device 15. This metal tube 10
When welding the abutting surfaces of the metal tube 10, since the introduction tube 6 that guides the optical fiber 2 is pressed against the inner wall of the metal tube 10 on the opposite side to the welding surface 17, the metal tube 10 is continuously formed and fed. Even if vibration or the like occurs, the introduction pipe 6 can always be positioned on the opposite side to the welding surface 17, and the distance between the introduction pipe 6 and the welding surface can always be kept constant. Therefore, the introduction tube 6 and the optical fiber 2 guided by the introduction tube 6
It is possible to reduce the thermal effect of welding on. Furthermore, since the introduction tube 6 and the optical fiber 2 near the welding part are cooled by the cooling gas 4 continuously supplied from the supply tube 4, the thermal influence of welding can be further reduced. In addition,
Although a case has been described in which the butt portions of the metal tubes 10 are laser welded, the thermal effects of welding can be similarly reduced when welding is performed by TIG welding or the like.

Further, since the introduction pipe 6 is pressed against the inner wall on the opposite side to the welding surface 17, its position does not move and the distance from the welding surface can always be maintained at the maximum. Even if welding spatter accumulates on the upper surface, it does not come into contact with the metal tube 10, allowing long-time operation.

The metal tube 10 with the butt portion welded and containing the optical fiber 2 is reduced in diameter to a predetermined diameter by the aperture means 22 and sent to the capstan 23 . A difference is created in the tension between the metal tube 10 and the optical fiber 2 on the inlet side of the capstan 23, and the tension between the metal tube 10 and the optical fiber 2 is reduced by the capstan 23. The amount of elongation between the optical fiber 10 and the optical fiber 2 is made different to control the extra length. The metal tube coated optical fiber cable 25 whose surplus length has been controlled passes through a dancer roll stand 26 and is wound up by a winder 27.

[0021] While manufacturing the metal tube coated optical fiber cable 25 in this manner, the optical fiber 2 sent to the guide tube 3 has dust in the air still attached to the surface coating. Therefore, a part of the cooling gas 4 supplied from the supply pipe 5 is sent to the inlet side of the guide pipe 3 through the communication hole 8 of the introduction pipe connecting fitting 7 with the guide pipe 3, and is ejected from the inlet of the guide pipe 3. By blowing out the cooling gas 4, dust adhering to the coated surface of the optical fiber 2 is expelled to the outside. Therefore, there is no dust attached to the optical fiber 2 entering the introduction tube 6, and there is no dust attached to the inner wall of the introduction tube 6.
It can prevent it from accumulating and remaining in the pipe.

In the above embodiment, the case where the cooling gas 4 is supplied from the supply pipe 5 has been described, but by supplying an inert gas, the welding part can be protected and the introduction pipe 6 and the optical fiber 2 can be cooled. At the same time, dust attached to the optical fiber 2 can be removed. Furthermore, even if a waterproof filling material is supplied from the supply pipe 5 and filled into the metal tube 10, and a portion of this filling material overflows from the inlet of the guide tube 3, the same effect as in the above embodiment can be obtained. can play.

[0023]Although the above embodiment has been described using a straight introduction tube 6, an introduction tube curved approximately in an L-shape with a constant curvature may also be used.

FIG. 3 shows an inlet pipe 61 curved into an approximately L-shape.
An example is shown below. As shown in the figure, a curved introduction pipe 61 is connected to the guide pipe 3 and the supply pipe 5 using the introduction pipe connecting fitting 7, and while the optical fiber 2 is fed from the vertically arranged guide pipe 3, the supply pipe 5 is used for cooling or cooling. Supply gas for purging or gel for waterproofing. This optical fiber 2 and gas etc. are passed through the introduction tube 61 into the metal tube 1.
0, some of the gas is jetted out from the inlet side of the guide tube 3, or the filling material is allowed to overflow into the container 31, thereby causing the gas to adhere to the surface of the optical fiber 2 sent to the guide tube 3. Dust can be removed. Note that the filling material overflowing into the container 31 is collected through the suction pipe 32.

[0025] When the introduction tube 61 curved in a substantially L-shape with a constant curvature is used as described above, when the introduction tube 61 is inserted into the metal tube 10, the entire introduction tube 61 is pressed downward.
By utilizing the elastic force of the curved portion bent at a constant curvature, the introduction tube 61 can be moved to the inner wall of the metal tube 10 on the side opposite to the welding surface near the welded portion without requiring a pressurizing mechanism that applies a downward pressing force. Can be pressure-welded to.

Furthermore, although each of the above embodiments has been described with reference to the case where the gas or the filler is supplied separately from the supply pipe 5, the gas and the filler can also be supplied simultaneously. For example, as shown in FIG. 4, a gas introduction joint 43 to which a gas supply pipe 42 is connected is provided at the upper part of the guide pipe 3a having the filler overflow hole 41. Then, while sending the optical fiber 2 through the gas introduction joint 43 and the guide tube 3a to the curved introduction pipe 61, gel, which is a waterproofing filling, is supplied from the supply pipe 5 and sent through the introduction pipe 61 into the metal tube 10. . While causing a part of the filling to overflow from the overflow hole 41 of the guide tube 3a, gas is supplied from the gas supply tube 42 to the optical fiber 2.
is ejected from the inlet of the gas introduction joint 43 into which the gas is introduced. By supplying the gas and the filler at the same time in this way, after the dust adhering to the optical fiber 2 is removed by the gas jet, the remaining dust can be further removed by the overflow of the filler, and the inlet pipe 61 is It is possible to more reliably prevent dust from entering.

Furthermore, although each of the above embodiments has been described using a single introduction tube, as shown in FIG. Introductory tube 5 for filling material that covers introductory tube 51 for filling material
An introduction pipe 62 consisting of two double pipes may also be used. Then, the guide tube 3 is connected to the gas supply tube 42 and the optical fiber introduction tube 51 using the introduction tube connecting fitting 7, and the supply tube 5 for supplying the filling material and the introduction tube 52 for the filling material are connected. While introducing the optical fiber 2 and the cooling gas or inert gas into the metal tube 10 using the fiber introduction tube 51, dust attached to the surface of the optical fiber 2 can be removed with a part of the gas. In this case, the filler supplied from the supply pipe 5 passes between the optical fiber introduction tube 51 and the filler introduction tube 52 and is sent into the metal tube 10, so that the optical fiber 2
The optical fiber can be inserted into the metal tube 10 while maintaining a constant tension without being affected by the viscous resistance of the filling when passing through a thin introduction tube, and the extra length of the optical fiber can be controlled with high precision. You can also do it.

Furthermore, although the embodiment shown in FIG. 5 has been described with reference to the case where the gas supply pipe 42 is connected to the introduction pipe connecting fitting 7, as shown in FIG.
Even when connected, the same effect as in the above embodiment can be achieved.

[0029]

Effects of the Invention As explained above, the present invention uses an introduction tube inserted into a metal tube to feed an optical fiber or an optical fiber bundle and one or both of a gas and a filler into the metal tube. Dust adhering to the surface of the optical fiber or optical fiber bundle is purged from the guide tube entrance by causing part of the filler to overflow from the entrance of the guide tube that guides the optical fiber or optical fiber bundle. Since it is possible to reduce the amount of dust entering the tube and prevent it from remaining inside the introduction tube, the optical fiber can be smoothly passed through the introduction tube even during long-term operation. Furthermore, since no dust remains in the introduction tube, no extra backward tension is applied to the optical fiber passing through the introduction tube, and the extra length of the optical fiber can be controlled with high precision.

Furthermore, at the welding part of the metal tube, the introduction tube is inserted and fixed so that it comes into elastic pressure contact with the inner wall of the metal tube on the opposite side to the welding surface, and the metal tube is fed while being continuously formed. Since the introduction pipe is always located on the opposite side of the welding surface, even if vibrations occur in the It is possible to reduce the thermal influence of welding on the optical fiber guided by the filling material and the optical fiber, and to reliably prevent damage due to heat.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the invention.

FIG. 2 is an overall configuration diagram of the above embodiment.

FIG. 3 is a sectional view showing a second embodiment of the invention.

FIG. 4 is a sectional view showing a third embodiment of the invention.

FIG. 5 is a sectional view showing a fourth embodiment of the invention.

FIG. 6 is a sectional view showing a fifth embodiment of the invention.

[Explanation of symbols]

1 Optical fiber introduction equipment 2 Optical fiber 3 Guide tube 5 Supply pipe 6 Introductory pipe 61 Introductory pipe 62 Introductory pipe 7 Introductory pipe connection fittings 10 Metal pipe

Claims (7)

[Claims] Claim 1. A method for manufacturing a metal tube coated optical fiber, in which an optical fiber or a bundle of optical fibers is introduced into a metal tube formed by forming a continuously fed metal strip and welding the abutted portions, the method comprising: The optical fiber or optical fiber bundle and the gas or filler are connected to a guide tube that guides the fiber bundle and a supply tube that supplies either one or both of gas or filler, and is inserted into the metal tube. A metal tube-coated optical fiber characterized in that a part of the gas and/or the filling is allowed to overflow from the entrance of a guide tube that guides the optical fiber or optical fiber bundle while feeding one or both of the above into the metal tube. Production method. Claim 2: Claim 1, wherein the gas is an inert gas.
A method of manufacturing the metal tube coated optical fiber described above. Claim 3: Claim 1, wherein the gas is a cooling gas.
A method of manufacturing the metal tube coated optical fiber described above. 4. The method for manufacturing a metal tube-coated optical fiber according to claim 1, wherein the filler is a waterproof material. 5. The method of manufacturing a metal tube coated optical fiber according to claim 4, wherein the introduction tube is elastically pressed against the inner wall of the metal tube on the opposite side to the welding surface at the welded portion of the metal tube. 6. A metal tube-coated optical fiber manufacturing apparatus in which an optical fiber or optical fiber bundle is introduced into a metal tube formed by forming a continuously fed metal strip and welding the abutted portions. A guide tube that guides the fiber bundle, a supply tube that supplies either one or both of a gas or a filler, and a supply tube that is inserted into the metal tube and that supplies the optical fiber or the optical fiber bundle and one or both of the gas and the filler. An introduction pipe that sends the gas into the metal pipe, and a guide pipe that connects the supply pipe and the introduction pipe, and a part of the gas and/or filling sent from the supply pipe is aligned with the traveling direction of the optical fiber or optical fiber bundle of the guide pipe. 1. An apparatus for manufacturing a metal tube-coated optical fiber, characterized in that the apparatus comprises a connecting portion for sending the optical fiber in the opposite direction. 7. The apparatus for manufacturing a metal tube-covered optical fiber according to claim 6, wherein the introduction tube is elastically pressed against the inner wall of the metal tube on the opposite side to the welding surface at the welded portion of the metal tube.