Holder and power cable connection method

Abstract

To reduce the burden of connecting a power cable.SOLUTION: A retaining device 10 has a retaining member 20 for retaining a diameter expansion retaining cylinder 70 in a removal operation of the diameter expansion retaining cylinder 70 which is pre-inserted into a central hole 81 of an insulating tube 80 which is fitted in a contracted state to cover a conductor connection portion 91 of a power cable 90, 90 and retains the central hole 81 in an expanded diameter. The retaining member 20 includes an end retaining portion 22 which suppresses axial movement of the axial end of the diameter expansion retaining cylinder 70, and a support portion 40 which supports the end retaining portion 22 to suppress its axial movement.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a holder for a diameter-expanding holding cylinder inserted into a central hole of an insulating cylinder coated and attached to a conductor connection part of a power cable, and a method for connecting power cables.

Background Art

[0002] Conventionally, when connecting power cables to each other, the insulating layers at the connection ends of the respective power cables are removed to expose the conductors, and the conductors are electrically connected in a butted state. The conductor connection part is coated with an insulating cylinder made of an insulating material while being inserted into the central hole. As the insulating cylinder, a room-temperature shrinkable tube having high shrinkability was used, and it was possible to closely adhere to the conductor connection part inside the central hole without a gap by its shrinking force.

[0003] Before connecting the conductors of the power cables, the above shrinkable insulating cylinder had to be passed through one of the power cables in advance, and after connecting the conductors, it had to be moved to a position where the conductor connection part could be covered. Therefore, in order to improve workability, a spiral core having an inner diameter larger than the outer diameter of the power cable was inserted into the central hole of the insulating cylinder in advance to hold the central hole with an expanded diameter. The spiral core is a cylindrical body formed by integrally winding a string-like body in a spiral shape. After arranging the insulating cylinder at a position where the conductor connection part can be covered, the string-like body of the spiral core is removed while unwinding from one end, and the insulating cylinder is shrunk from one end (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, an insulating cylinder made of a heat-shrinkable tube with a spiral core inserted therein has been used for the connection part between high-voltage power cables. Since high-voltage power cables have a large outer diameter and require high insulation performance, an insulating cylinder with a large outer diameter is also used. However, since the heat-shrinkable force of an insulating cylinder with a large outer diameter is extremely large, in the operation of removing the spiral core, if the remaining length becomes short, it may jump out vigorously from the end of the insulating cylinder. Therefore, it is necessary for the operator to firmly hold the insulating cylinder, the power cable, and the spiral core by hand to perform the operation, resulting in a heavy work burden.

[0006] An object of the present invention is to reduce the burden of the connection work of power cables.

Means for Solving the Problems

[0007] To solve the above problems, the present invention is a holder having a holding member for holding a diameter-expanding holding cylinder body, which is preliminarily inserted into a central hole of an insulating cylinder coated in a shrunk state on a conductor connection part of a power cable and holds the central hole in a diameter-expanded state, in an operation of removing the diameter-expanding holding cylinder body, wherein the holding member has an end holding part for suppressing the axial movement of the axial end of the diameter-expanding holding cylinder body, and a supporting part for supporting to suppress the axial movement of the end holding part, and is characterized by having the above.

[0008] To solve the above problems, another aspect of the present invention is a method for connecting power cables, comprising: forming a conductor connection part by connecting the connection end of one power cable with the connection end of the other power cable in a state where the connection end of one power cable is passed through the diameter-expanding holding cylinder body inserted into the central hole of the insulating cylinder, and holding the axial end of the diameter-expanding holding cylinder body by the holder described above to suppress the axial movement thereof. It is characterized by performing the removal operation of the cylinder body for maintaining the diameter expansion.

Effects of the Invention

[0009] According to the present invention, it is possible to reduce the burden of the connection work of the power cable, suppress the protrusion of the spiral core from the end of the insulating cylinder, and improve the safety of the work.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0011] [First Embodiment] The first embodiment of the present invention will be described with reference to FIGS. 1 to 8. This embodiment relates to a work of removing a spiral core 70 as a diameter-expanding holding cylinder inserted into a central hole 81 of an insulating cylinder 80 for insulating a conductor connection portion 91 connecting conductors 92 of power cables 90, 90, a holder 10 for holding the spiral core 70, and a method of connecting the power cables 90, 90 using the same.

[0012] [Power Cable] FIG. 1 shows a state in which an insulating cylinder 80 is disposed on a conductor connection portion 91 to cover the conductor connection portion 91 connecting conductors 92, 92 in the process of forming an intermediate connection portion of power cables 90, 90. The ends of the power cables 90, 90 are sequentially stripped of a vinyl sheath 94 and an insulating layer 93 to expose the conductors 92, and the conductor connection portion 91 is formed by a well-known method such as connecting the conductors 92, 92 with a connection pipe.

[0013] [Insulating Cylinder] The insulating cylinder 80 is a room-temperature shrinkable tube, and as shown in FIG. 1, includes a cylindrical insulating layer 82 in which a central hole 81 is formed, inner semi-conductive layers 84 formed at a longitudinal intermediate position and both ends on the inner peripheral portion of the insulating layer 82, and an outer semi-conductive layer 83 formed so as to cover the entire outer peripheral surface of the insulating layer 82. The insulating layer 82 is formed of an insulating material such as silicone rubber, ethylene propylene rubber, or chloroprene, and the inner semi-conductive layer 84 and the outer semi-conductive layer 83 are formed of a semi-conductive rubber in which carbon is added to the insulating material. Further, the insulating layer 82, the inner semi-conductive layer 84, and the outer semi-conductive layer 83 are integrally formed.

[0014] The inner diameter of the central hole 81 of the insulating cylinder 80 was originally set to be smaller than the outer diameters of the power cable 90 and the conductor connection part 91. Before being mounted on the conductor connection part 91, a spiral core 70 with an inner diameter larger than the outer diameter of the power cable 90 is inserted and mounted in the central hole 81 of the insulating cylinder 80. By previously inserting the power cable 90 inside the spiral core 70, the insertion of the power cable 90 into the insulating cylinder 80 is facilitated. Then, after the conductors 92, 92 of the power cables 90, 90 are connected to each other to form the conductor connection part 91, the insulating cylinder 80 is arranged at a position where it can cover the conductor connection part 91, and then the spiral core 70 is removed, so that the insulating cylinder 80 is shrunk to enable close contact with the outer peripheral surfaces of the power cables 90, 90 and the conductor connection part 91. In this state, the insulating cylinder 80 covers the entire periphery of the conductor connection part 91 from the tip of the vinyl sheath 94 and the insulating layer 93 of one power cable 90 to the tip of the vinyl sheath 94 and the insulating layer 93 of the other power cable 90.

[0015] [Spiral Core] The spiral core 70 is formed into a cylindrical shape as a whole, for example, by spirally winding a plastic string-like body 71 and fusing or fitting the side surfaces of the adjacent string-like bodies 71 to each other. The inner diameter dimension of the spiral core 70 is set to be larger than the outer diameter of the power cable 90. By mounting the spiral core 70 in the central hole 81 of the insulating cylinder 80, the insertion of the power cable 90 is facilitated, and the insulating cylinder 80 can be arbitrarily moved with respect to the power cable 90. One end of the string-like body 71 constituting the entire spiral core 70 can be pulled along its center line direction to separate the string-like body 71 into a string shape. As a result, the spiral core 70 can be sequentially disassembled from one end and removed from the inside of the insulating cylinder 80. In addition, in the removal operation of the spiral core 70, the string-like body 71 separated from one end (the right end in FIG. 1) of the spiral core 70 is drawn out to the other end side (the left end in FIG. 1) through the inside of the spiral core 70.

[0016] [Insulator Attachment Work] Figures 2(A) to 2(C) are explanatory diagrams showing the steps of attaching the insulator 80 to the conductor connection parts 91 of the power cables 90, 90. Here, the basic attachment work without using the holder 10 will be described. First, with one of the power cables 90 passed through the spiral core 70 inside the insulator 80, the conductors 92, 92 of the power cables 90, 90 to be connected are connected, and a predetermined process is performed to form the conductor connection part 91. After that, as shown in Fig. 2(A), the insulator 80 is arranged so that the conductor connection part 91 is inside the central hole 81 of the insulator 80, and one end of the string-like body 71 of the spiral core 70 is pulled out from the inside of the spiral core 70 to the opposite end, and the spiral core 70 is disassembled from one end side. As a result, as shown in Fig. 2(B), the insulator 80 contracts from one end side, and its inner peripheral surface adheres closely to the outer peripheral surfaces of the stepped peeling part of the power cable 90 and the conductor connection part 91. Then, as shown in Fig. 2(C), when the disassembly and removal of the spiral core 70 are completed, the insulator 80 adheres closely to the stepped peeling parts of the power cables 90, 90 and the conductor connection part 91, covering all of them, and the attachment is completed.

[0017] [Overall Structure of the Holder] When the removal work of the spiral core 70 is performed without using the holder 10, each power cable 90, insulator 80, and spiral core 70 are supported by the operator's hand. In this state, as shown in Fig. 2(B), when the remaining part of the spiral core 70 becomes less, there is a risk that the spiral core 70 may pop out from the insulator 80 due to the strong contraction force of the insulator 80. To avoid this, the operator has to bear a greater workload, such as holding each power cable 90, insulator 80, and spiral core 70 more firmly and pulling the string-like body 71 of the spiral core 70 more carefully. The holder 10 reduces such a workload and aims to improve workability.

[0018] FIG. 3 is a side view showing a state in which the insulating cylinder 80 and the spiral core 70 are held by the holder 10. Hereinafter, the direction along the central axis of the insulating cylinder 80 is referred to as the axial direction, the direction along the circumference centered on the central axis is referred to as the circumferential direction, and the direction along the radius of the circumference is referred to as the radial direction. Further, the axial direction may be referred to as the front-rear direction, one of the axial directions may be referred to as "front", and the other may be referred to as "rear". Furthermore, the horizontal direction orthogonal to the front-rear direction may be referred to as the left-right direction, and the left side as viewed from the front may be referred to as "left" and the right side as "right". As shown in the figure, the holder 10 includes a holding member 20 that holds the spiral core 70, a pedestal 30 on which the insulating cylinder 80 is disposed, and a connecting member 40 as a supporting portion that connects the holding member 20 to the pedestal 30.

[0019] [Pedestal] FIG. 4 is a front view of the pedestal 30 as viewed from the side of the holding member 20, which is one of the axial directions, and FIG. 5 is a cross-sectional view taken along line V-V in FIG. 4. The pedestal 30 includes a main body portion 31 that supports the insulating cylinder 80 from below, a pair of front and rear end face plates 35 erected inside the lower side of the main body portion 31, a reinforcing plate 36 provided between the pair of end face plates 35 on the lower side of the main body portion 31, and a connecting ring 37 for connecting a wire, a rope, a chain, etc. for suspending the pedestal 30. The main body portion 31, the end face plates 35, and the reinforcing plate 36 are entirely composed of a metal plate. However, some or all of these members may be composed of a resin material plate if the strength is sufficient.

[0020] The main body portion 31 has a receiving plate 32 in the shape of a half-peripheral surface, top plate portions 33, 33 connected to both ends in the diameter direction of the receiving plate 32, and side plate portions 34, 34 connected to the outer edge portions of the respective top plate portions 33, 33. The receiving plate 32, the top plate portions 33, 33, and the side plate portions 34, 34 are integrally formed.

[0021] The receiving plate 32 has a shape obtained by halving a cylinder and is used with its inner peripheral surface facing upward. The receiving plate 32 supports the insulating cylinder 80 from below with the lower half of the insulating cylinder 80 fitted inside it. Therefore, the inner diameter of the receiving plate 32 is substantially the same as or slightly larger than the maximum outer diameter of the insulating cylinder 80.

[0022] The top plates 33, 33 are in the shape of rectangular flat plates and are individually connected to the left and right outer edge portions of the receiving plate 32. The front - rear lengths of the top plates 33, 33 and the receiving plate 32 are equal. The top plates 33, 33 are used with their planes substantially horizontal. Also, cushion layers 321, 331, 331 made of an elastic material such as sheet - like rubber are formed on the inner peripheral surface of the receiving plate 32 and the upper surfaces of the top plates 33, 33 so as to cover the entire respective surfaces.

[0023] Side plates 34, 34 are individually connected to the outer edge portions on the left - right outer sides of each top plate 33, 33. Each side plate 34, 34 is in the shape of a rectangular flat plate along the front - rear direction and the up - down direction. The front - rear lengths of each side plate 34, 34 and each top plate 33, 33 are equal. Also, the dimension of the height in the up - down direction of each side plate 34, 34 is larger than the radius of the receiving plate 32. Mounting holes 341, 341 for attaching the connecting ring 37 are drilled at one axial end and the other axial end at the upper part of each side plate 34, 34.

[0024] The connecting ring 37 is an annular member that can be fixed to each mounting hole 341 by a fastening member such as a bolt (not shown). Since the connecting ring 37 is annular, a wire or a rope can be inserted through it, or a chain can be connected to it. The connecting ring 37 is attached to the four corners in the plan view of the receiving base 30 according to the arrangement of the above - mentioned mounting holes 341. For this reason, the receiving base 30 can be stably suspended from four directions.

[0025] Each end panel 35 has a vertical plate portion 351 composed of a flat plate perpendicular to the front-rear direction, and a bottom plate portion 352 composed of a horizontal flat plate connected to the lower end portion of the vertical plate portion 351. The vertical plate portion 351 and the bottom plate portion 352 are integrally formed. For the front end panel 35, the bottom plate portion 352 extends forward, and for the rear end panel 35, the bottom plate portion 352 extends backward. And the vertical plate portion 351 of each end panel 35 conforms to the front view shape of the lower region (inner region) of the main body portion 31 and is joined to the lower side of the main body portion 31 in a fitted state. Therefore, the pedestal 30 has high strength against loads in the left-right direction. Also, the bottom surface of the bottom plate portion 352 is at the same height as the lower edge portions of the respective side plate portions 34, 34 of the main body portion 31 in a state where the end panel 35 is joined to the lower side of the main body portion 31.

[0026] The reinforcing plate 36 is a vertically standing flat plate that is long in the front-rear direction. The upper end portion of the reinforcing plate 36 is joined to the bottom of the receiving plate 32 of the main body portion 31. Also, the front end portion and the rear end portion of the reinforcing plate 36 are respectively joined to the vertical plate portions 351 of the front and rear end panels 35. Thereby, the reinforcing plate 36 can suppress the deflection of each end panel 35 with respect to the main body portion 31. Also, the corners between the bottom of the receiving plate 32 and the front vertical plate portion 351 and between the bottom of the receiving plate 32 and the rear vertical plate portion 351 of the reinforcing plate 36 are cut off. Therefore, the reinforcing plate 36 can maintain high joint strength against the deflection between each end panel 35, 35 and the receiving plate 32.

[0027] The pedestal 30 has a function of supporting from below in a state where the central axis of the insulating cylinder 80 is substantially horizontal in the removal operation of the spiral core 70. Furthermore, the pedestal 30 also has a function of holding the holding member 20 at a predetermined interval forward with respect to the pedestal 30 in the removal operation of the spiral core 70.

[0028] To realize the former function, the cradle 30 is suspended by connecting the lower ends of wires, ropes or chains to the connecting rings 37 provided at the four corners. The upper ends of the wires, ropes or chains are hooked to two hooks F attached to a rail member R provided along the extension direction of the power cables 90, 90 vertically above the power cables 90, 90. Each hook F is attached to the rail member R so as to be position-adjustable along the rail member R. The rail member R is installed, for example, on a structure S such as a scaffold installed at the construction site for the conductor connection work of the power cables 90, 90 or on the wall surface of the construction site in a temporary state. Note that the rail member R may be installed permanently. Also, if the floor surface of the construction site for the conductor connection work of the power cables 90, 90 is a horizontal flat surface and there is sufficient space below the power cables 90, 90, the cradle 30 may be placed on the floor instead of being suspended. In that case, if height adjustment is required, height-adjusting plates or blocks may be interposed.

[0029] Also, to realize the function of holding the holding member 20 at a predetermined interval in front of the cradle 30, as shown in FIG. 1, mounting holes 353 of the connecting member 40 are formed through the upper left and right ends and the lower generally middle portion in the left-right direction (slightly to the left) of the upright plate portion 351 of the front end face plate 35. The three connecting members 40 are support portions that support to suppress the axial movement of the holding member 20. Each connecting member 40 is a round bar with male threads formed at both ends. The rear end portion thereof is individually inserted into each mounting hole 353, and the upright plate portion 351 is clamped and fixed by a pair of nuts 41 and a pair of washers 42. Thereby, each connecting member 40 maintains a state parallel to the front-rear direction while the other end portion extends forward. The front end portions of the three connecting members 40 also support the holding member 20 by being clamped by a pair of nuts 41 and a pair of washers 42. Since male threads are also formed on the front end portion side of each connecting member 40, the distance of the holding member 20 in the front-rear direction with respect to the cradle 30 can be adjusted and fixedly held.

[0030] Note that the connecting member 40 is not limited to three, and one or more may be used. Further, the connecting member 40 does not have to be in the shape of a round bar, and may be in other forms such as a plate shape. Furthermore, the front end portion of the receiving base 30 may be extended further forward to support the holding member 20 at the front end portion of the receiving base 30.

[0031] [Holding member] FIG. 6 is a front view of the holding member 20, and FIG. 7 is a cross-sectional view taken along the line W-W of FIG. 6. The holding member 20 includes a flat plate-shaped main body portion 21, an end holding portion 22 that holds the front end portion of the spiral core 70, and a reinforcing plate 23.

[0032] The main body portion 21 is formed of a rectangular flat plate that is wide in the left-right direction and has a shape in which the lower left and right corners are cut off. Mounting holes 211 for the connecting member 40 are formed through the upper left and right end portions of the main body portion 21 and three locations in the lower substantially middle portion in the left-right direction (slightly to the left). The front end portion of each connecting member 40 is individually inserted into each mounting hole 211, and the main body portion 21 is clamped by a pair of nuts 41 and a pair of washers 42 to support the holding member 20. Each mounting hole 211 is an elongated hole along the vertical direction, and the support position of the holding member 20 can be adjusted vertically.

[0033] By each connecting member 40, the flat plate surface of the main body portion 21 is supported by the connecting member 40 in a state substantially parallel to the vertical direction and the horizontal direction. A semi-circular notch 212 that is concave downward is formed at the center in the left-right direction on the upper edge portion of the main body portion 21, and the end holding portion 22 is joined to the notch 212.

[0034] The end holding portion 22 has an outer peripheral wall portion 221 and an inner peripheral wall portion 222 that are concentric and have different outer diameters, and an inner bottom portion 223 that closes one axial end portion of the outer peripheral wall portion 221 and the inner peripheral wall portion 222. The outer peripheral wall portion 221 is formed of a curved plate along the peripheral surface in the range of half a circumference, and the inner peripheral wall portion 222 is formed of a curved plate along the peripheral surface having a smaller diameter than the outer peripheral wall portion 221 in the range of half a circumference. The inner diameter of the outer peripheral wall portion 221 is slightly larger than the outer diameter of the spiral core 70, and the outer diameter of the inner peripheral wall portion 222 is slightly smaller than the inner diameter of the spiral core 70. The end holding portion 22 is formed with a semi-circular concave groove 224 that opens rearward, where the outer peripheral wall portion 221, the inner peripheral wall portion 222, and the inner bottom portion 223 are integrally joined.

[0035] The semi-circular notches 212 of the outer peripheral wall portion 221, the inner peripheral wall portion 222, and the main body portion 21 are arranged to be concentric with the receiving plate 32 of the main body portion 31 of the receiving base 30 in a state where the holding member 20 is supported by the receiving base 30 via each connecting member 40. Note that "being concentric" means that when the holding member 20 is vertically adjusted with respect to each connecting member 40 along each long hole-shaped mounting hole 211, it can be made concentric within the adjustment range.

[0036] The reinforcing plate 23 is a flat plate that stands vertically with respect to the main body portion 21 on the front side of the main body portion 21 below the end holding portion 22. The upper end portion of the reinforcing plate 23 is joined to the outer peripheral surface of the outer peripheral wall portion 221, and the rear edge portion of the reinforcing plate 23 is joined to the front surface of the main body portion 21. Thereby, the reinforcing plate 23 can suppress the deflection of the end holding portion 22 with respect to the main body portion 21.

[0037] [Connection Method of Power Cable] The connection direction of the power cables 90, 90 using the holder 10 will be described based on the flowchart of FIG. 8. First, the vinyl sheaths 94 and the insulating layers 93 of both power cables 90, 90 are sequentially stripped step by step to expose the conductors 92 (step S1: stripping step).

[0038] Next, insert the connection end of one power cable 90 into the spiral core 70 inside the insulating cylinder 80 and insert it until it protrudes from the end on the opposite side of the inserted end (Step S3: Insulating cylinder insertion process). At this time, the insulating cylinder 80 may perform the insertion operation of the power cable 90 while being supported from below by the pedestal 30. Further, the insertion operation may be performed while moving the pedestal 30 that supports the insulating cylinder 80 along the rail member R.

[0039] Next, connect the conductors 92, 92 of the power cables 90, 90 to each other by a well-known method such as connecting them with a connecting pipe to form a conductor connection portion 91 (Step S5: Conductor connection process). Then, move the insulating cylinder 80 along the power cables 90, 90 and align it with a position where the conductor connection portion 91 can be covered (Step S7: Insulating cylinder alignment process). Also in this case, the alignment operation may be performed while moving the pedestal 30 that supports the insulating cylinder 80 along the rail member R.

[0040] Note that the lifting height of the pedestal 30 is adjusted so that the central axis of the receiving plate 32 is substantially concentric with the central axes of the power cables 90, 90 while maintaining a posture in which the central axis is horizontal. At this time, when the insulating cylinder 80 is stable inside the receiving plate 32 due to its own weight, the operator may perform the operation while pressing the insulating cylinder 80 or may perform the operation without pressing it.

[0041] Next, insert the end of the spiral core 70 (the end on the pulling-out side of the string-like body 71) until it abuts or approaches the inner bottom portion 223 at the back of the semi-circular concave groove 224 of the holding member 20, and hold the spiral core 70 so that it does not come out of the insulating cylinder 80 during the pulling-out operation of the string-like body 71 (Step S9: Spiral core holding process). Note that this process may be performed in parallel when placing the insulating cylinder 80 on the pedestal 30 (for example, Step S3).

[0042] Next, the extraction of the string-like body 71 is started from the end portion of the spiral core 70 on the side opposite to the end portion where the extraction of the string-like body 71 begins (the extraction side end portion of the string-like body 71) (step S11). As a result, the insulating cylinder 80 contracts from one end side, and its inner peripheral surface adheres tightly to the outer peripheral surfaces of the stepped peeling portion of the power cable 90, the conductor connection portion 91, and the like.

[0043] In the initial stage of the extraction operation of the string-like body 71, the spiral core 70 does not move (pop out) with respect to the insulating cylinder 80. However, as the spiral core 70 becomes shorter, the holding force of the spiral core 70 by the insulating cylinder 80 decreases, and relatively, the force pushing out the spiral core 70 to the extraction side end portion of the string-like body 71 increases. However, since the movement of the spiral core 70 to the extraction side of the string-like body 71 is restricted by the holding member 20, the popping out of the spiral core 70 is suppressed. Note that the upper portion of the front end portion of the spiral core 70 exposed from the end portion holding portion 22 may be pressed by the operator during the operation, or the operation may be performed without pressing.

[0044] Then, when the remaining length of the spiral core 70 reaches the range protruding forward from the front end portion of the insulating cylinder 80, the insulating cylinder 80 contracts over its entire length and adheres in a state of covering all the stepped peeling portions and the conductor connection portions 91 of each power cable 90. Thereby, an intermediate connection portion of the power cables 90, 90 is formed (step S13). On the other hand, the spiral core 70 pulls the string-like body 71 to disassemble all the rest, removes it from the connected power cables 90, 90, and ends the operation.

[0045] [Technical Effects in the First Embodiment] In the above-described holder 10, the end portion holding portion 22 of the holding member 20 suppresses the forward movement of the front end portion of the spiral core 70. For this reason, in the removal operation of the spiral core 70, the popping out from the front end portion of the insulating cylinder 80 that occurs when the remaining length thereof becomes short is effectively suppressed. Therefore, the need for an operator to hold the spiral core 70 while paying attention to the protrusion of the spiral core 70 is reduced, the burden of the connection work of the power cable can be reduced, and the work safety can be improved.

[0046] In addition, since the end holding portion 22 of the holding member 20 holds half of the range in the circumferential direction of the front end portion of the spiral core 70, the front end portion of the spiral core 70 can be easily installed with respect to the end holding portion 22, and the workability can be improved. In addition, in order to hold at least half of the range in the circumferential direction of the front end portion of the spiral core 70, the protrusion of the spiral core 70 can be sufficiently and effectively suppressed.

[0047] In particular, since the end holding portion has the concave groove 224 into which the front end portion of the spiral core 70 can be inserted, it can be installed only by inserting the front end portion of the spiral core 70 into the end holding portion 22, and the workability can be further improved.

[0048] In addition, the holder 10 has a pedestal 30 for arranging the insulating cylinder 80, and the holding member 20 is connected to the pedestal 30. Therefore, if the insulating cylinder 80 is arranged on the pedestal 30, the protrusion of the spiral core 70 forward can be suppressed or blocked, and the burden of the connection work of the power cable can be further effectively reduced.

[0049] Note that the concave groove 224 of the end holding portion 22 has a structure that holds half of the circumferential direction of the front end portion of the spiral core 70, but it may also have a structure that holds a larger range in the circumferential direction, or even the entire circumference. In addition, the end holding portion 22 only needs to have a configuration having an opposing surface that presses against at least the front end portion of the spiral core 70. For example, instead of a concave groove, it may be a concave portion in which the entire front end portion of the spiral core 70 is stored. Also, it does not have to face the entire predetermined range in the circumferential direction at the front end portion of the spiral core 70. For example, it may have an opposing portion (for example, claw-shaped, hook-shaped, etc.) that faces a plurality of locations scattered within the predetermined range in the circumferential direction at the front end portion of the spiral core 70. In addition, a predetermined circumferential range at the front end of the spiral core 70 is preferably at least half of the circumferential direction, but may be less than half. Although the stability when suppressing the protrusion of the front end of the spiral core 70 decreases, it may be configured to hold at least one point in the circumferential direction at the front end of the spiral core 70.

[0050] [Second Embodiment] FIG. 9 is a front view of the holder 10A according to the second embodiment, and FIG. 10 is a side view of the holder 10A. The power cable, insulating cylinder, and spiral core to which the holder 10A is applied are the same as the power cable 90, insulating cylinder 80, and spiral core 70 described above. Note that the holder 10A of the present embodiment does not have a configuration corresponding to the pedestal 30 described above, and has a configuration including a holding member 20A and handles 40A as a plurality of supporting portions. The holding member 20A and the plurality of handles 40A are formed of a metal material, but if the strength is sufficient, a part or all of the configuration may be formed of resin.

[0051] The holding member 20A has a main body portion 21A held by the spiral core 70 and an end holding portion 22A that holds the front end portion of the spiral core 70.

[0052] The main body portion 21A is composed of two main body units 210A that are symmetric with respect to the central axis of the spiral core 70. The main body portion 21A has a cylindrical portion that can be inserted inside the front end portion of the spiral core 70 and a flange portion that projects radially outward from the front end portion of the cylindrical portion. The two main body units 210A constituting the main body portion 21A have a structure in which the main body portion 21A is halved along the center line direction. That is, the main body unit 210A is composed of a semi-cylindrical portion 212A obtained by halving the cylindrical portion of the main body portion 21A and a semi-flange portion 211A obtained by halving the flange portion of the main body portion 21A. The semi-flange portion 211A projects radially outward from the front end portion of the semi-cylindrical portion 212A and has a substantially semi-circular shape.

[0053] The half-split flange portion 211A has connecting arm portions 213A, 213A extending toward both sides in the diameter direction thereof. Each of the connecting arm portions 213A, 213A is formed with an insertion hole through which a connecting bolt 214A, which is a fastening member, is inserted. Then, with respect to the two main body units 210A, 210A, they are faced to each other so that their cross-sectional surfaces match, the connecting bolt 214A is inserted into the insertion holes of the opposing connecting arm portions 213A, 213A, and the connecting arm portions 213A, 213A on both sides are connected to each other with a wing nut 215A as a fastened member. Thereby, the pair of main body units 210A, 210A can be connected to form a main body portion 21A having a cylindrical portion and a flange portion.

[0054] Note that the connecting bolt 214A and the wing nut 215A may be composed of a normal bolt and nut, or the connecting bolt 214A may be composed of a wing bolt and the wing nut 215A may be composed of a normal nut.

[0055] The end holding portion 22A is composed of four end holding units 220A provided at uniform intervals in the circumferential direction with respect to the flange portion of the main body portion 21A. Note that the number of the end holding units 220A may be two or more and is not limited to four. However, it is preferably provided on each of the two half-split flange portions 211A.

[0056] Each end holding unit 220A includes a support block 221A mounted on the rear surface side of each half-split flange portion 211A, mounting bolts 222A as two fastening members for fixing the support block 221A to the half-split flange portion 211A of the main body portion 21A, a gripping member 224A that grips the front end portion of the spiral core 70 by cooperation with each half-split cylindrical portion 212A, and a wing bolt 223A as a fastening member that presses the gripping member 224A toward the half-split cylindrical portion 212A side to apply a gripping pressure.

[0057] The support block 221A is formed of a rectangular parallelepiped and is fixed to the rear surface side of the half-split flange portion 211A in a direction perpendicular to the radial direction of the half-split cylindrical portion 212A with a pair of planes parallel to each other. The support block 221A has two insertion holes for the mounting bolts 222A formed along the axial direction. The half flange portion 211A also has two insertion holes for the mounting bolts 222A. Then, the mounting bolts 222A are inserted through the insertion holes of the support block 221A and the insertion holes of the half flange portion 211A, and a nut 225A as a fastened member is fastened on the front side of the half flange portion 211A. Note that the mounting bolts 222A are also inserted through the base end portion of the handle 40A on the front side of the half flange portion 211A, and the support block 221A and the handle 40A are simultaneously fastened and fixed.

[0058] In addition, the support block 221A is also formed with screw holes that penetrate a pair of parallel planes in the radial direction described above. A wing bolt 223A is screwed into these screw holes from the outside in the radial direction. The tip of the wing bolt 223A abuts against the surface (the back surface) on the outside in the radial direction of the gripping member 224A, and the gripping member 224A is pressed radially inward by tightening the wing bolt 223A.

[0059] The gripping member 224A is composed of a peripheral surface plate along the outer peripheral surface of the spiral core 70. A recess for the tip of the wing bolt 223A to fit into may be formed on the back side of the gripping member 224A. The surface on the inside in the radial direction (the gripping surface) of the gripping member 224A is pressed radially inward by the wing bolt 223A, and the spiral core 70 can be gripped by the gripping member 224A and the semi-cylindrical portion 212A. Therefore, an uneven structure that bites and holds the outer peripheral surface of the spiral core 70 is formed on the gripping surface side of the gripping member 224A. Since four end holding units 220A are provided at uniform intervals in the circumferential direction, the front end portion of the spiral core 70 can be gripped at four locations in the circumferential direction.

[0060] The four handles 40A are attached to the front side of the half flange portion 211A in an arrangement that coincides with each end holding unit 220A in the circumferential direction. The handle 40A is a rod-shaped body extending radially outward from the semi-cylindrical portion 212A. The base end portion has a plate shape that is wider than the extending end portion. The base end portion of the handle 40A is formed with insertion holes through which the two mounting bolts 222A of the aforementioned end holding unit 220A are inserted, and is fixed to the semi-flange portion 211A together with the support block 221A of the end holding unit 220A. By the operator pressing the extending portions of the four handles 40A by hand, the spiral core 70 can be pressed.

[0061] [Connection Method of Power Cable] The connection direction of the power cables 90, 90 using the holder 10A will be described. In this case as well, refer to the flowchart of FIG. 8 described above. First, each layer of both power cables 90, 90 is step-stripped to expose the conductors 92 (step S1: step-stripping process). Then, after inserting the connection end portion of one power cable 90 into the insulating cylinder 80 (step S3: insulating cylinder insertion process), the conductors 92, 92 of the power cables 90, 90 are connected by a well-known method to form a conductor connection portion 91 (step S5: conductor connection process). Furthermore, the insulating cylinder 80 is moved to a position where it can cover the conductor connection portion 91 (step S7: insulating cylinder alignment process). Note that after step S3, the insulating cylinder 80 is supported by the operator so that the central axis is horizontal at an appropriate height together with each power cable 90, 90. The insulating cylinder 80 may be suspended by a rope, chain, etc. from a structure such as a scaffold installed at the construction site or the ceiling surface of the construction site at an appropriate height. Also, the insulating cylinder 80 may be placed on the floor or ground with a cushioning material or the like laid on its lower side to adjust the height.

[0062] Then, the two half body units 210A are connected by a connecting bolt 214A and a wing nut 215A so that the power cable 90 is inserted inside in a state in front of the spiral core 70. At this time, each semi-cylindrical portion 212A of the main body portion 21A is directed rearward. Then, the cylindrical part composed of two semi-cylindrical parts 212A is inserted into the front end part of the spiral core 70. At this time, the cylindrical part is inserted until the front end part of the spiral core 70 abuts or approaches the rear surface of the semi-flange part 211A. Then, the wing bolts 223A of each end holding unit 220A are fastened, and the front end part of the spiral core 70 is gripped by each gripping member 224A. Thereby, the holding member 20A is fixed to the front end part of the spiral core 70, and a state is achieved in which the spiral core 70 can be held so as not to come out of the insulating cylinder 80 during the pulling-out operation of the string-like body 71 (Step S9: Spiral core holding step). Note that this step may be performed at an earlier stage after Step S3.

[0063] Then, while the operator holds each handle 40A of the holder 10A by hand, the pulling-out of the string-like body 71 is started from the end part (the end part to which the holding member 20A is attached) on the side opposite to the end part where the string-like body 71 in the spiral core 70 starts to be untied (Step S11). Thereby, the insulating cylinder 80 contracts from one end side, and its inner peripheral surface adheres closely to the outer peripheral surfaces of the stepped peeling part of the power cable 90, the conductor connection part 91, etc.

[0064] In the initial stage of the pulling-out operation of the string-like body 71, the spiral core 70 does not move (pop out) with respect to the insulating cylinder 80. However, as the spiral core 70 becomes shorter, the holding force of the insulating cylinder 80 on the spiral core 70 decreases, and the force for pushing out the spiral core 70 relatively increases at the end part on the pulling-out side of the string-like body 71. However, since the front end part of the spiral core 70 is supported by the operator through the handle 40A of the holder 10A, the shortened spiral core 70 is held so as not to pop out from the central hole 81 of the insulating cylinder 80.

[0065] When the remaining length of the spiral core 70 reaches the range protruding forward from the front end of the insulating cylinder 80, the insulating cylinder 80 contracts over its entire length and closely adheres in a state of covering all the step-stripped portions and conductor connection portions 91 of each power cable 90. Thereby, an intermediate connection portion of the power cables 90, 90 is formed (step S13). On the other hand, when the holding tool 10A loosens each wing bolt 223A to release the gripping state of the spiral core 70, and removes the wing nut 215A from the connecting bolt 214A to separate the two main body units 210A, the holding tool 10A is removed from the intermediate connection portion of the power cables 90, 90. Also, the spiral core 70 pulls the string-like body 71 to disassemble all the rest, removes it from the connected power cables 90, 90, and ends the operation.

[0066] [Technical Effects in the Second Embodiment] Since the operator can support the spiral core 70 by holding each handle 40A provided on the holding member 20A that holds the end of the spiral core 70, the holding tool 10A can easily suppress the forward protrusion of the front end portion of the spiral core 70. Therefore, it is possible to reduce the burden on the operator for the connection work of the power cable and improve the safety of the work.

[0067] In particular, since each handle 40A has a structure extending radially outward from the holding member 20A, the work of supporting the spiral core 70 to maintain the posture along the power cable 90 can be performed with less labor, and it is possible to further reduce the burden on the operator for the connection work of the power cable. Also, due to the structure in which the spiral core 70 is supported by the handle 40A, the overall configuration of the holding tool 10A can be miniaturized, and the work burden of installation can be reduced.

[0068] In addition, since each end holding unit 220A of the end holding portion 22A is structured to grip the front end portion of the spiral core 70 from the radial direction, it is possible to easily and effectively attach the holder 10A to the spiral core 70 and hold the spiral core 70. As a result, it is possible to further reduce the burden on the operator for the work of connecting the power cable.

[0069] [Others] As described above, each embodiment of the present invention has been explained. However, the present invention is not limited to the above embodiments. For example, in the embodiments, a component integrally formed by a single member may be replaced with a component formed by dividing a plurality of members and connecting or fixing them to each other. Also, a component formed by connecting a plurality of members may be replaced with a component integrally formed by a single member. In addition, the details shown in the embodiments can be appropriately changed without departing from the gist of the invention.

[0070] For example, the holder 10A may be configured to include a pedestal 30. In that case, instead of the handle 40A, attachment holes may be provided in each half flange portion 211A of the main body portion 21A of the holding member 20A, and the holding member 20A and the pedestal 30 may be connected by a plurality of connecting members 40.

Explanation of Reference Numerals

[0071] 10, 10A Holder 20 Holding member 21 Main body portion 211 Attachment hole 212 Notch 22 End holding portion 221 Outer peripheral wall portion 222 Inner peripheral wall portion 223 Inner bottom portion 224 Concave groove 20A Holding member 21A Main body portion 210A Main body unit 211A Half flange portion 212A Half cylindrical portion 213A Connecting arm portion 214A Connecting Bolt 215A Wing Nut 22A End Holding Part 220A End Holding Unit 221A Support Block 222A Mounting Bolt 223A Butterfly Bolt 224A Gripping Member 225A Nut 30 Base 31 Body Part 32 Receiving Plate 321 Cushion Layer 33 Top Plate Part 331, 331 Cushion Layer 34 Side Plate Part 341 Mounting Hole 35 End Panel 351 Standing Plate Part 352 Bottom Plate Part 353 Mounting Hole 36 Reinforcing Plate 37 Connecting Ring 40 Connecting Member (Supporting Part) 40A Handle (Supporting Part) 41 Nut 42 Washer 70 Spiral Core (Cylinder for Diameter Expansion Retention) 71 String-like Body 80 Insulating Cylinder 81 Central Hole 82 Insulating Layer 90 Power Cable 91 Conductor Connection Part 92 Conductor 93 Insulating Layer 94 Vinyl Sheath F Hook R Rail Member

Claims

1. A holder having a holding member for holding a diameter-expanding holding cylinder, which is preliminarily inserted into a central hole of an insulating cylinder covered in a contracted state on a conductor connection portion of a power cable and holds the central hole with an expanded diameter, in a removal operation of the diameter-expanding holding cylinder, wherein the holding member has an end holding portion that suppresses axial movement of an axial end portion of the diameter-expanding holding cylinder, and a support portion that supports the axial movement of the end holding portion, and is characterized by having the above.

2. The holder according to claim 1, wherein the end holding portion holds a range of at least half in the circumferential direction of an axial end portion of the diameter-expanding holding cylinder.

3. The holder according to claim 2, wherein the end holding portion has a concave groove into which a range of at least half in the circumferential direction of an axial end portion of the diameter-expanding holding cylinder can be inserted.

4. The holder according to claim 1, wherein the end holding portion has a structure that clamps an axial end portion of the diameter-expanding holding cylinder from the radial direction of the diameter-expanding holding cylinder.

5. having a pedestal for arranging the insulating cylinder, and the holder according to claim 1, wherein the holding member is connected to the pedestal.

6. The holder according to claim 1, wherein the support portion is a handle for manually supporting the holding member.

7. The holder according to claim 6, wherein the handle extends radially outward from the end holding portion to the diameter-expanding holding cylinder.

8. With the connection end portion of one power cable passed through the diameter-expanding holding cylinder inserted into the central hole of the insulating cylinder, the connection end portion of the other power cable is connected to form a conductor connection portion, the axial end portion of the diameter-expanding holding cylinder is held by the holder according to claim 1 to suppress the axial movement, and a connection method for a power cable, characterized by performing a removal operation of the diameter-expanding holding cylinder.

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