Abstract:
An auxiliary tool for cable hauling capable of restraining a tip end of a cable, which is exposed due to cutting on a cable laying site, with a restraint force enough to withstand a hauling force, and being applied even on a laying site where pipe size is small. A tension member ( 51 ) is exposed and is inserted into and received in a tip end receiving section ( 2   a ) and further is inserted through one of insertion holes ( 41 ) of a restraint member ( 4 ) and held back to be inserted through an other insertion hole ( 41 ). The tension member ( 51 ) thus held back is held on itself to be subjected to clamping with a first clamping member ( 42   b ). The tip end receiving section ( 2   a ) and a connection section ( 2   b ) are screw-engaged with each other in a state in which the restraint member ( 4 ) is received in the tool.

Description:
FIELD OF THE INVENTION 
     This invention is related to an auxiliary tool for cable hauling which is used to link a cable tip end with a hauling means at a laying site of communication cable such as an optical fiber cable or other cable such as an electrical wire. 
     BACKGROUND OF THE INVENTION 
     The demand for communication network construction has increased steadily with multimedia development in recent years. Especially, in communication networks such as CATV and intranets, optical fiber cables are generally used because their capacity and communication speed are excellent. 
     As shown in FIG. 8, a tension member  51  of an optical fiber cable  5  is connected to a connecting tool  7  for cable hauling. Connecting tool  7  is linked with hauling means such as a winch, and then optical fiber cable  5  is hauled at a laying site thereof. When the tension member  51  is connected to the connecting tool  7 , a tip end of the tension member  51  is inserted into a tip end insertion hole  71 , and restraint portion  72  is clamped using specialized equipment, thereby restraining the tip end of the optical fiber cable  5 . The restraint portion  72  has such a small diameter that it has to be clamped by specialized equipment under high pressure. As a result, the tip end of tension member  51  will not disconnect from connecting tool  7 , even if it is hauled with a traction of approximately 800 Kgf. 
     However, the above-described specialized clamping equipment cannot be used at the laying site of the cable. A cable that is cut at the laying site cannot be connected to the connecting tool. A tip end of the cable, which is exposed by cutting, will be difficult to link to a hauling means with sufficient restraint force. 
     In the case of delivered cable that has already been connected to a connecting tool by clamping with specialized equipment, such connecting tool may not be suitable for use at certain laying sites because of the diameter of its laying tube. If unable to be used, the connecting tool will have to be cut off from the cable tip end. 
     Further, this connecting tool is too long to turn in a 90° bend of the laying tube, which is turning up from a horizontal tube to a vertical tube. 
     The object of the present invention is to solve the above mentioned problems. The invention provides an auxiliary tool for cable hauling capable of constraining a cable tip end which is exposed due to cutting off at a cable laying site, with sufficient restraint force to withstand a hauling force, and can be used even at a laying site where the pipe diameter size is small. 
     SUMMARY OF THE INVENTION 
     In the present invention, an auxiliary tool for cable hauling is provided which links a cable tip end with a hauling means to haul said cable for laying comprising: a container containing a cable tip end; a linkage interconnected with said hauling means, said linkage being connected to said container; a restraint means restraining said cable tip end; wherein said restraint means is contained and held in said container in such a manner that said restraint means restrains said cable tip end. Since neither the cable tip end nor the restraint means thereof is exposed, both are out of contact with the inner wall of the laying tube. Furthermore, problems such as hooking or breaking off will not occur. The cable tip end is linked with the hauling means by a linkage tool, providing a reliable and strong linkage. 
     Further, an auxiliary tool for cable hauling is provided which comprises: a container containing said cable tip end; a linkage interconnected with said hauling means, said linkage being connected to said container; a restraint means restraining said cable tip end; said container being divisible into a tip end container portion and a linking portion, said tip end container portion containing an inserted cable tip end, said linking portion being connected to a linkage. After a cable tip end is restrained by restraint means, it is installed in the container easily. 
     Furthermore, if a restraint member which is a different body from said container and is freely rotatable is used as the restraint means, it will efficiently prevent twists while cable hauling. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective illustration which shows the structure of an auxiliary tool for hauling cable of Embodiment 1. 
     FIG. 2 is side sectional view which illustrates a condition of the cable tip end restrained by an auxiliary tool for hauling cable of Embodiment 1. 
     FIG. 3 is a graph which compares restraint forces of restraint means of this embodiment and of prior art. 
     FIG. 4 is a perspective view of another restraint member. 
     FIG. 5 is a perspective view of the connecting portion of an auxiliary tool for hauling cable of Embodiment 2. 
     FIG. 6 is an exploded perspective illustration which shows the structure of an auxiliary tool for hauling cable of Embodiment 3. 
     FIG. 7 is a side section which describes a condition of an auxiliary tool for hauling cable connected to the tip end thereof. 
     FIG. 8 is a partial cutaway view of connecting toll for hauling cable of a prior art. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides an auxiliary tool which restrains the tip end of a cable to link with hauling equipment at a laying site of communication line, such as optical fiber cable or an electrical wire, passing through a pulley or laying tube. 
     The auxiliary tool for hauling comprises a container, a restraint means which is installed in the container, and a linking member which interconnects to hauling equipment. The container utilizes a compact design for smooth hauling in a narrow groove of a pulley or laying tube. 
     Preferably, a restraint member is used as a restraint means. The restraint member is freely rotatable around the axis along the cable tip end, and therefore, twisting of the cable while hauling thereof is eliminated. In most cases, when a linking portion which is interconnected with hauling equipment contacts the groove wall of a pulley or inner wall of a laying tube, the linking portion rotates. However, rotation of the linking portion does not convey to the restraint member. The restraint member restrains the tip end of the cable and is not stressed because it is freely rotatable as mentioned above. The cable is thereby prevented from separating during hauling. 
     Various types of restraint members may be used. For example, restraint members may have insertion spaces to insert a cable tip end, such as insertion holes or insertion hollows as described later. To achieve the object of the invention, restraint members of a variety of sizes are selected depending on the type of cable, and a suitable type of container for the selected restraint member is used. Cable can be installed utilizing a narrow existing laying tube having 20 mm diameter or less, up to a big sub-ground tube having a diameter of more than 500 mm. 
     Further, in addition to only one cable being hauled by one auxiliary tool, a plurality of cables, such as a combination of a communication cable and an electrical wire, are capable of being hauled simultaneously by one auxiliary tool if a proper restraint member is selected. Particularly, although the restraint portion could potentially be easily twisted because of unequal tension forces existing when a plurality of cables are hauled, an auxiliary tool can be used to eliminate this twist. As a result, the effect of the invention is more efficiently achieved. 
     Embodiment 1 
     In Embodiment 1, a restraint member restrains a cable tip end as a means of restraining a cable, and the restraint member is put in a container. Thereby, the cable tip end is restrained in the container. 
     As shown in FIG. 1, an auxiliary tool  1  for hauling cable consists of container  2 , a linkage  3  and a restraint member  4 . The container  2  comprises a tip end container portion  2   a , which cable tip end is inserted and stored therein, and a linking portion  2   b , to which linkage  3  is joined. The linkage  3  is joined with container  2  and links with a hauling means. The restraint member  4  restrains a cable tip end and is installed in container  2 . The tip end container portion  2   a  and the linking portion  2   b  are secured to each other by threads  21   a  and  21   b . The restraint member  4  includes restraint metal fitting  40  and clamping members  42   a  and  42   b  (Refer FIG.  2 ). The restraint metal fitting  40  is held on the end of thread  21   a  when tip. end container portion  2   a  and linking portion  2   b  are secured to each other and tension is loaded on the cable tip end. The restraint metal fitting  40  is freely rotatable about an axis of the cable tip end. 
     The restraint metal fitting has six insertion holes  41 . A cable tip end is inserted through the insertion holes  41  and is restrained by clamping of clamping members  42   a  and  42   b  as described below. Therefore, the restraint metal fitting  40  is installed in the container  2  after restraining the cable tip end, and then the cable tip end is restrained by the auxiliary tool  1 . 
     The diameter of restraint metal fitting  40  is slightly smaller than the inner diameter of container  2  therearound. Therefore, the restraint metal fitting  40  is freely rotatable about an axis of the cable tip end in the container  2 . Accordingly, even if the cable twists while hauling thereof, the twist will be eliminated by rotation of restraint metal fitting  40 . The cable tip end restrained by the restraint metal fitting is not stressed and is prevented from wrenching off thereof. 
     An Example of Cable Hauling Using an Auxiliary Tool  1  of Embodiment 1. 
     In this example, an optical fiber cable is hauled. A tension member is a wick wire located within the optical fiber cable. The wick wire is used as a tension member by the auxiliary tool because tension cannot be applied to the optical fibers directly. 
     As shown in FIG.  2 ( a ), a tension member  51  is exposed to haul the covered optical fiber cable  5 . The tension member  51  is inserted through an insertion hole  41  and is bent back to be inserted through another insertion hole  41 . 
     As shown in FIG.  2 ( b ), tension member  51  is bent back,is inserted through another insertion hole  41 , and then is restrained by restraint metal fitting  40 . Since its restraint force is not enough for hauling thereof, it is clamped to be restrained. The tension member, which is turned back, is clamped with the first clamping member  42   a . The tension member is bent back again and is clamped with the second clamping member  42   b  and is thereby strongly restrained by the restraint member  4 . 
     Installing the restraint member  4  that restrains tension member  51 , the tip end container portion  2   a  and the linking portion  2   b  are secured to each other. The tip end of optical fiber cable  5  is restrained by an auxiliary tool  1  and then it sufficiently withstands hauling. 
     The restraint forces of the restraint member of this invention, as well as the prior method using a clamping member only, are hereby compared. 
     A test wire is restrained by a clamping member which is used in the above Embodiment. Another test wire is restrained by restraint member of the Embodiment. These were hauled by a tension tester and the load was measured just before separation failure. 
     Incidentally, the strength limit of test wire was exceeded and the wire was torn off when it was clamped twice as per the above Embodiment in a tension test. Therefore, only one clamping member is used for a restraint member in comparing the tension tests. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Details of the tension test 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1. 
                 Test mode 
                 single (upward) 
               
               
                 2. 
                 Speed 
                 10 mm/min 
               
               
                 3. 
                 Load cell 
                 500 kgf 
               
               
                 4. 
                 F/S Load 
                 500 kgf 
               
               
                   
               
             
          
         
       
     
     As shown in FIG. 3, the maximum load of restraint by the restraint member of this Embodiment was half as much again as the maximum load of restraint by only one clamping member. The time up to separation failure was more than doubled. 
     One optical fiber cable was hauled in the Embodiment. Since restraint metal fitting  40  of the Embodiment has six insertion holes  41 , it can haul up to three cables. The advantages of hauling a plurality of cables are the following: 
     (a) Regarding hauling force, three times as much hauling force for one cable is not required when three cables are being hauled. For instance, even if 100 kgf is required to haul one cable, three cables can be hauled with 200 kgf. Thus, the tension in each cable sharply reduces to 66 Kgf when three cables are hauled. Such reduction of load on the cables effectively prevents the cables from tearing off. 
     (b) When cables are laid on multiple floors or at several positions of one floor, each cable was respectively laid by prior art. However, in the Embodiment, multiple cables are simultaneously and efficiently hauled. Each cable tip end is cut and connected to desired points individual. 
     Although restraint metal fitting  40  has six insertion holes, the present invention is not restricted by the Embodiment. For example, as shown in FIG. 4, a main insertion hole  41   a  and insertion sub-holes  41   b  around a main insertion hole  41   a  are provided. The cable, which wires are intertwined, is inserted through the main insertion hole  41   a , each wire is untied, and each wire is inserted through insertion sub-holes  41   b . The wires are bound and are restrained by the double clampings. 
     A variety of restraint metal fittings could be applied if it is installed in a container and restrains a cable tip end by double clampings. The number of cables is also selected depending on the type of restraint metal fitting. 
     Embodiment 2 
     In the auxiliary tool for hauling cable of Embodiment 2, restraint means, which restrains the cable tip end, is provided on a linking portion of the container. As shown in FIG. 5, a linking portion  6  of Embodiment 2 is the same shape as the linking portion  2   b  of Embodiment 1. A restraint portion  60  is formed as one body on the linking portion  6  to restrain a cable tip end. An insertion hole  61  is bored on the tip of the restraint portion  60 . 
     Embodiment 3 
     As shown in FIG. 6, an auxiliary tool for cable hauling of Embodiment 3 uses a restraint metal fitting  40   b  as a restraint means. The restraint metal fitting  40   b  has insertion hollows  41   c  instead of insertion holes of the above Embodiments. 
     The restraint metal fitting  40   b  is preferably utilized to restrain the tip end of a cable possessing too thick a diameter to insert into an insertion hole of the above Embodiments. Alternately, Embodiment 3 is preferably used in an auxiliary tool for hauling a cable having a small diameter because insertion holes are impossible to be bored on the restraint metal fitting. 
     When a cable tip end is restrained by restraint metal fitting  40   b , as shown in FIG. 6, a tension member  51  is inserted into the insertion hollows  41   c  after it is bent back, and then restrained with a clamping member  42   a  as per Embodiment 1 above. 
     Further, this restraint metal fitting  40   b  has a large diameter portion  43   b  and a small diameter portion  44   b . When a cable tip end is restrained and installed in a container, as shown in FIG. 7, the small diameter portion  44   b  is contained in the tip end container portion  2   a , but the large diameter portion  43   b  is held on the end of the tip end container portion  2   a . The tip end container portion  2   a  and the linking portion  2   b  are secured to each other (refer FIG.  2 ), and then the restraint metal fitting  40   b  is held in the container  2  so that it is freely rotatable about an axis of the cable tip end. 
     Therefore, the present invention achieves the following effects: 
     (1) A cable tip end is easily restrained by using a clamping pliers tool at the laying sight, without specialized equipment. 
     (2) Since a plurality of cables are capable of being hauled simultaneously, they will be hauled more efficiently and load on the cables will be reduced. 
     (3) Even in a narrow laying tube, cables can be smoothly hauled because the hauling means of the cable tip end has enough restraint force, and is designed small, which is shorter than the prior art. Particularly, when the cable is turned up from a horizontal tube to a vertical tube, the cable is simply hauled in the corner of tube, without using a switchboard. 
     (4) Because the restraint metal fitting which restrains the cable is freely rotatable in the container, twisting of the cable is eliminated and breaking off or separation failure by twisting stress is prevented. 
     Industrial Applicability 
     An auxiliary tool for cable hauling of this invention is useful to haul communication cables such as an optical fiber cable or other cable such as electrical wires. Particularly, a cable tip end is strongly restrained to link a tip end thereof with a hauling means, and it is contained in a container and is hauled without exposing the cable tip end in the laying tube.