JPS6235086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical cable, and in particular, provides a method for manufacturing an optical cable having a structure in which even if tension is applied to the cable, no tension is applied to the optical fiber. Although many optical cable structures have been proposed in the past, many of these structures generate tension in the optical fiber when the cable is stretched. If an optical fiber is subjected to tension, it will either break or its lifespan will be shortened, so it is most ideal that no tension be applied to the optical fiber in an optical cable under any circumstances. . The most effective cable structure is one in which one or more optical fibers are in contact with the inner wall of the tube while being bent in a spiral shape. The present invention provides a continuous manufacturing method for such an optical cable.

The optical fiber referred to in the present invention may be a glass fiber for light transmission, an all-plastic fiber for light transmission, or a fiber whose periphery is coated with silicon or plastic. The manufacturing method for creating an optical fiber in spiral contact with the inner wall of a pipe has never been realized, perhaps because it was considered to be extremely difficult. However, according to the present invention, it can be manufactured very easily, so such an ideal optical cable structure can be easily realized. The present invention is characterized in that the optical fibers are once twisted on a vibrating spindle, and then separated from the tip of the spindle so that they are in contact with the inner wall surface of the pipe.For details, see the drawings below. I'll explain it as I go along. FIG. 1 shows a typical structural example of a conventional optical cable, and many cable structures basically adopt this structure. A plurality of optical fibers 1 are twisted around a tension member 2 and protected by a suitable jacket 3 around its outer periphery. The purpose of tension member 2 is
The purpose is to suppress the stretch of the entire cable so that excessive tension is not applied to the optical fiber, but in such a structure, if the tension member stretches, the optical fiber will inevitably stretch in proportion to that stretch. be. The reason is that the optical fiber 1 is tightly wound around the tension member 2. When an optical fiber is stretched, tension is generated within the optical fiber, which may cause it to break at that point, or even if it does not break, it may affect its lifespan and shorten the time it takes to break. In particular, since cable stretching is unavoidable in submarine cables and overhead cables, it is considered necessary for these cables to have a cable structure in which the optical fiber does not stretch at all even if the cable stretches. Such a cable structure is as shown in FIG. A
B is a cross-sectional view of the cable, and B is a partial longitudinal cross-sectional view. In the figure, as an example, optical fiber 1 is 4
A case is shown in which the book is in contact with the inner wall surface of the tube 4 in a spirally curved manner. With this configuration,
Even if the entire cable 5 is stretched in the axial direction, no tension is applied to the optical fiber. In other words, when the tube stretches, the pitch of the helix of the helical optical fiber stretches, but the optical fiber 1 itself does not stretch. This is the same situation as when a coil spring stretches, but the wire that makes up the spring does not. In particular, unlike the structure of FIG. 1 in which the fiber is in close contact with the tension member, this structure does not have a tension member, so the tension member does not prevent the movement of the fiber. Since it can fall in the direction of , that is, toward the central axis, no tension is applied to the optical fiber even when the cable is stretched excessively. FIG. 3 is an example of another cable structure to which the manufacturing method of the present invention can be applied, and shows one in which a central tension member 2 is added to the structure of FIG. 2. The one in Figure 1 is
The difference is that the tension member 2 is not in close contact with the fiber 1. In other words, even though the tension member 2 is provided in the one shown in Fig. 3, the optical fiber 1
Since the optical fiber 1 is in contact with the inner surface of the tube 4 and not in close contact with the tube 4, when the cable stretches, the optical fiber 1 does not stretch due to the same effect as that shown in FIG.

The present invention provides a continuous manufacturing method for optical cables of the type shown in FIGS. 2 and 3. FIG. 4 is a diagram explaining the principle of the present invention, in which a plurality of optical fibers 1 (the figure shows a case where there are two optical fibers for simplicity) are arranged in a cylindrical cage that rotates as shown by the arrow. It is unwound from a fiber winding reel 11 mounted inside the fiber reel 10. The unwound optical fiber 1 is twisted onto an elongated spindle 51.
This spindle 51 is suitably a round metal rod and vibrates. The frequency is suitably in the ultrasonic range, but the present invention is not necessarily limited to ultrasonic vibrations. An oscillation source 50 is attached to one end of the spindle 51, and the oscillation source 50 excites the spindle 51. spindle 51
The reason for vibrating is to reduce the mechanical resistance when the optical fiber 1 twisted thereon moves from right to left in the figure. In other words, when the spindle 51 vibrates at a frequency in or around the ultrasonic range, the coefficient of friction between the spindle 51 and the optical fiber 1 spirally wound thereon becomes almost 0. Therefore, the helical fiber can easily slide over the top of the spindle from right to left in the figure while remaining in a helical state.

In order to promote the advancement of the fiber, it is preferable that the supply tension of the optical fiber 1 has a value of 0 or a negative value. To do this, the optical fiber 1 fed out from the reel 11 must be set to zero or negative winding tension (that is, axial pushing force) using something like a tension helper (not shown) just before it is wound around the spindle 51. It is preferable to

Spindle 51 excited by oscillation source 50
The direction of vibration is not particularly limited. In other words, the vibration may be in the axial direction, the radial direction, or a combination of these two directions. In short, it is preferable to apply vibration in a direction that gives the lowest coefficient of friction with the fiber. Also, the spindle may or may not rotate about its axis. In special cases, it is also possible to make the same rotation as the cage 10. In this case, the cage 10, the oscillation source 50, and the spindle 51 may be integrated. The end of the spindle 51, which is not attached to the oscillation source 50, is inserted into a suitable pipe-making device 41 and terminated there. The spindle 51 is discontinued in the tube 4 formed by the tube making device 41.

In this way, the fiber 1 twisted on the spindle 51 maintains its helical state, and when it slides on the spindle and comes into contact with the tube 4, it is twisted due to the lubricating force between the inner surface of the tube 4 and the fiber 1. In this state, it advances closely to tube 4. To summarize the above mechanism, the spindle 5
1 and the optical fiber 1 is almost 0, but since the friction between the tube 4 and the optical fiber 1 is large, the spirally bent fiber 1 moves on the spindle 51 in that state, and the tube 4 At the point where it touches the tube, it separates from the spindle 51 and moves forward while remaining in contact with the inner wall surface of the tube 4. Therefore, an optical cable as shown in FIG. 2 is manufactured in which no tension is applied to the fiber 1 even when the tube 4 is stretched. The cable thus obtained is taken off to the left in the figure by a capstan or winder (not shown). FIG. 5 shows another embodiment of the invention, in which the tube is obtained by longitudinally molding a plastic tape. The plastic tape 42 forming the tube 4 is unwound from the tape pad 40, rolled into a tube shape in a tube former 41, and then wrapped with another tape or thread 43 to maintain the pipe shape. One end of the spindle 51 is
Inside the tube former 41, the tape 42 is inserted to the point where it is formed into a complete tube. The fiber 1 thus spirally wound around the spindle 51 comes into contact with the inner surface of the tube 4 and advances together with the tube 4. Note that 12 is a tension helper, which is driven and rotated as shown by the arrow, so the winding tension on the spindle is 0.
～Since it can be made negative (that is, pushing force), fiber 1
This contributes to pushing the spiral state into the tube 4. This was mentioned in the explanation of Figure 4.

FIG. 6 also shows another embodiment of the invention, in which the tube 4 is obtained by extrusion of plastic. That is, the tube 4 is extruded by the crosshead section 41 of the extruder 44, and in this case, one end of the spindle 51 is inserted to a position at the outlet of the crosshead where the tube is completely formed. The position is approximately as indicated by the dotted line in the figure. The manufacturing mechanism in this case is also shown in Figure 4 and Figure 5.
This is the same as explained in the figure. Furthermore, Figure 5,
In Figure 6, the cage 10 and reel 1 in Figure 4 are shown.
It should be noted that although 1 etc. have been omitted, it is actually the same as in Figure 4.

In addition, as a suitable pipe-making device, it is also possible to vertically weld a metal tape and to vertically weld a plastic tape. In either case, one end of the spindle should be inserted until a complete tube is formed.

Note that if the direction of vibration of the spindle and the finishing method of its surface are carefully considered, it may be possible to provide an effect of transporting the spirally wound fiber toward the tube forming section. Furthermore, by making the inner wall surface of the tube adhesive or by modifying the condition of the inner surface of the tube, it is possible to more reliably take up the helical fiber with the tube. Fourth
In FIGS. 6 to 6, the explanation of the manufacturing method of the cable having the tension member at the center as shown in FIG. 3 is omitted. However, in order to manufacture the cable shown in FIG. through the
Just guide the tension member to the center of the cable.
In the cable shown in the second figure, a tensile strength member may be embedded in the tube 4 to give the tube the function of a tension member, or the tube 4 may be made of a material with low elongation so that the tube itself functions as a tension member. may be given. For example, a specific example of the latter is when the tube 4 is formed by longitudinally applying copper tape and electrically welding the abutted portions.

Since the present invention is as described above, it is possible to easily manufacture an optical cable in which the optical fiber does not stretch at all even if the entire cable is stretched. Also, in the explanations so far, there has been no mention of the structure outside the tube, but it is possible to provide a tension member on the outside of the tube, further protect it with metal, further apply a plastic sheath, etc. may be applied as appropriate depending on the usage situation of the cable. Furthermore, for example, the cables shown in Figures 2 and 3 can be used as a component of the entire optical cable, that is, as a unit, by twisting a plurality of cables around a more durable tension member and providing a suitable jacket over the entire cable. be. In the case of a multi-core optical cable, it would be a good idea to use the cables shown in the second and third figures as a unit. Furthermore, if necessary, when twisting a plurality of units in their entirety in a pipe, it may be done as shown in Figures 4, 5, and 6, or in the case of a copper cable, the coated copper wire may be spirally connected to the inner surface of the pipe according to the present invention. It is also possible to accommodate the In any case, according to the present invention, since the elongation of the entire cable is not converted into each filament accommodated inside, The significance is extremely great. In optical cables, there is an extremely strong requirement that no tension be applied to the optical fibers, regardless of the usage situation, so it is preferable that the present invention be applied to all optical cable transportation. In addition, in the optical cable obtained by the method of the present invention, a fiber length longer than the cable length is accommodated in the cable, so it is convenient when it is desired to pull out the extra length of the fiber for connection from the cable cutting part. It also has secondary but significant effects such as:

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a typical example of a conventional optical cable. FIGS. 2A and 2B and FIG. 3 are cross-sectional views of cable examples to which the manufacturing method of the present invention is applied. FIG. 4 is a diagram explaining the principle of the present invention. Fifth
6 are explanatory diagrams of other embodiments of the present invention. 1... Optical fiber, 2... Tension member,
3... Jacket, 4... Tube, 5... Cable (entire), 10... Cage, 11... Reel, 12... Tension helper, 40... Tape pad, 41... Tube making device, 42... tape, 4
3... Thread or tape, 44... Extruder.

Claims (1)

[Claims] 1. One or more optical fibers are wound or twisted around an elongated spindle that is excited and vibrated by an oscillation source provided at one end, and the other end of the spindle has a tube formed in a tube former. By inserting the optical fibers until they are completely formed, the optical fibers twisted on the spindle move in a spiral manner on the spindle and are wound into the capstan or wound while being in spiral contact with the inner wall of the tube. A method for manufacturing an optical cable, characterized in that the optical cable is collected at a machine. 2. The method of manufacturing an optical cable according to claim 1, wherein the tension of the fibers immediately before being twisted onto the spindle is set to zero or a negative value. 3. The method of manufacturing an optical cable according to claim 1, wherein the tube is formed by vertically applying plastic tape. 4. The method of manufacturing an optical cable according to claim 1, wherein the tube is formed by plastic extrusion. 5. Claim 1, characterized in that the tube is formed by vertical welding of metal tape.
2. Method for manufacturing an optical cable described in Section 1. 6. The method for manufacturing an optical cable according to claim 1, wherein the frequency of the spindle is in the ultrasonic range.