JP7707782B2 - Power cable terminal connection and method for manufacturing power cable terminal connection - Google Patents

Description

The present invention relates to a power cable termination connection part to which the termination part of a stepped stripped power cable is connected, and a method for manufacturing the same.

Conventionally, the present applicant has proposed a polymer joint for power cables, which is applied to devices such as transformers and gas-insulated switchgears, as disclosed in Patent Document 1. This polymer joint for power cables is mainly made of a polymer-based material and includes a polymer protective layer having a cable insertion hole into which the end of the power cable is inserted, an insulating plug that connects a compression terminal connected to the conductor of the power cable to the device-side conductor of the device, and a waterproof processing section that seals the rear end side of the polymer protective layer. The polymer protective layer includes an insulator made of a polymer-based material, first and second semiconductive sections that reduce the electric field of the power cable, a protective cover that protects the tip side of the insulator, and a metal tubular member provided on the rear end side of the insulator. The insulator, the first and second semiconductive sections, the protective cover, and the tubular member are integrally molded by molding. The waterproof processing section is formed by wrapping a waterproof tape with an adhesive layer around the outer circumference of the tubular member and the sheath of the power cable, and covering it with a heat-shrink tube. The tubular member has better adhesion to the waterproof tape than the insulating polymer protective layer, making it possible to perform waterproofing treatment reliably.

JP 2016-116277 A

In the case of the device described in Patent Document 1, if an earth wire is connected to the tubular member by a bolt to electrically ground it, the thickness of the tubular member needs to be increased. In this case, the rigidity of the tubular member increases, and it becomes difficult to insert and remove the mold member placed inside the tubular member when integrally molding the polymer protective layer by molding, which reduces workability. Furthermore, if the outer diameter of this mold member is reduced so that it can be easily inserted and removed from the tubular member, the molten polymer material will leak out from the gap between the mold member and the tubular member.

The present invention aims to provide a power cable termination connection part that is easy to manufacture and a method for manufacturing the same.

The present invention aims to solve the above problems, and provides a power cable termination connection part to which a termination part of a power cable having a central conductor, an insulating layer covering the outer periphery of the central conductor, a shielding layer consisting of a plurality of shield wires arranged to surround the outer periphery of the insulating layer, and a sheath covering the outer periphery of the shielding layer is connected, the power cable termination connection part comprising a cable holder having an insertion hole into which the central conductor and the insulating layer of the power cable are inserted, and a metal tubular member fixed to an end of the cable holder, through which the central conductor and the insulating layer are inserted and which accommodates a part of the shielding layer and the sheath, The cable holder has an insulator made of a polymeric material and a semi-conductor made of a polymeric material that has been made conductive by a conductive agent, the tubular member has an embedded portion embedded in the cable holder and a cylindrical portion exposed from the cable holder, the embedded portion and the cylindrical portion are aligned in the axial direction along the longitudinal direction of the power cable, the cylindrical portion has an annular step formed on the inner circumferential surface, and the inner diameter of the portion closer to the embedded portion than the step is smaller than the inner diameter of the portion opposite the embedded portion than the step.

The present invention also aims to solve the above-mentioned problems by providing a method for manufacturing the above-mentioned power cable terminal connection part, which includes an insulator molding process in which the insulator of the cable holder is injection molded using a rod-shaped mold member inserted inside the tubular member, and the rod-shaped mold member has an annular groove formed on the outer circumferential surface of a portion that is positioned closer to the embedded part than the step in the insulator molding process, and a ring-shaped elastic body is housed in the annular groove, and the elastic body elastically contacts the inner circumferential surface of the cylindrical part closer to the embedded part than the step.

The power cable terminal connection part and the manufacturing method thereof according to the present invention can improve the workability during the manufacturing of the power cable terminal connection part.

1 is a cross-sectional view specifically showing an example of a power cable connection structure according to an embodiment of the present invention. 2 is a cross-sectional view of the power cable taken along line AA in FIG. 1. 13A and 13B are side views of a third semiconductor body viewed from different directions. 1A is a perspective view showing a tubular member of a power cable, and FIG. 1B is a perspective cross-sectional view of the tubular member taken along line BB in FIG. FIG. 13 is an explanatory diagram showing a mold for molding an insulator together with a third semiconductive body. 1 is an explanatory diagram showing the first to third semi-conductors and the tubular member arranged in the lower die, together with the first and second columnar dies and the rod-shaped die; FIG. 1A is a perspective view showing a part of an upper mold, and FIG. 1B is a perspective view showing a part of a lower mold. 5A and 5B are explanatory views showing a manufacturing process of a power cable terminal connection part. FIG. 8( b ) is an enlarged view showing a part of FIG. 8( a ).

[Embodiment]
A power cable terminal connection part and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 9. Fig. 1 is a cross-sectional view specifically showing an example of a power cable connection structure including a power cable terminal connection part according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of a power cable taken along line A-A in Fig. 1. This power cable connection structure is a connection structure for connecting a power cable 1 that transmits high-voltage power to a power cable terminal connection part 2 provided, for example, under the floor of a railway vehicle.

(Configuration of power cable 1 and power cable terminal connection portion 2)
2, the power cable 1 has a central conductor 11 formed by twisting together a plurality of wires 111, an insulating layer 12 covering the outer periphery of the central conductor 11, a shielding layer 13 consisting of a plurality of shield wires 131 arranged to surround the outer periphery of the insulating layer 12, and a sheath 14 covering the outer periphery of the shielding layer 13. In this embodiment, an inner semiconductive layer 15 is provided between the central conductor 11 and the insulating layer 12, and an outer semiconductive layer 16 is provided between the insulating layer 12 and the shielding layer 13. A pressure winding tape 17 is spirally wound around the outer periphery of the shielding layer 13, and the outside of the pressure winding tape 17 is covered by the sheath 14.

The wire 111 of the central conductor 11 may be a wire material made of a metal with good electrical conductivity, such as a tin-plated soft copper wire. The central conductor 11 transmits a high voltage of, for example, 7000 V or more. The insulating layer 12 is formed by extruding a material such as ethylene propylene rubber, polyvinyl chloride, cross-linked polyethylene, silicone rubber, or a fluorine-based material. The sheath 14 is formed by extruding a rubber such as natural rubber, butyl rubber, halogenated butyl rubber, or non-halogenated polyolefin elastomer to which a cross-linking agent or the like has been added. The shield wire 131 is made of a wire material such as a tin-plated soft copper wire, and is wound laterally in a spiral shape.

The inner semiconductive layer 15 and the outer semiconductive layer 16 are provided to reduce the concentration of the electric field, and are mainly made of polymer-based materials, which are formed by extrusion molding of materials that have conductive powder dispersed therein to give them conductivity. The pressing and wrapping tape 17 can be, for example, a strip made of plastic or rayon.

The power cable 1 has a terminal end connected to the power cable terminal connection part 2 stripped in stages, exposing each layer in stages. Specifically, the sheath 14 and part of the pressure winding tape 17 are removed to expose the multiple shield wires 131, part of the outer semiconductive layer 16 is removed to expose the insulating layer 12, and further part of the insulating layer 12 and the inner semiconductive layer 15 are removed to expose the central conductor 11.

A compression terminal 10 is attached to the central conductor 11 exposed from the insulating layer 12. The compression terminal 10 has a cylindrical crimped portion 101 that is crimped to compress the central conductor 11, and a flat connecting portion 102 that is integral with the crimped portion 101. The crimped portion 101 has a receiving hole 101a that receives the central conductor 11. The connecting portion 102 has an equipment connecting hole 102a at its tip.

The connection portion 102 of the compression terminal 10 is connected to the device side conductor 91 of the device 9 to be connected by a nut 100 inside the power cable termination connection portion 2. The device 9 has a tapered device side bushing 90 and a device side conductor 91 exposed from the device side bushing 90. A male thread 91a is formed at the tip of the device side conductor 91.

The power cable terminal connection part 2 includes a cable holder 3 having an insertion hole 20 into which the central conductor 11 and insulating layer 12 of the power cable 1 are inserted, a metal tubular member 4 fixed to the end of the cable holder 3, a waterproofing treatment part 5 that prevents water from entering the inside of the tubular member 4, an insulating plug 61 that connects the compression terminal 10 to the equipment side conductor 91 of the equipment 9, and a protective cap 62 that protects the insulating plug 61.

The waterproofing treatment section 5 is formed by wrapping a strip-shaped member with good water resistance, such as a waterproof tape 51 such as a polyethylene tape with an adhesive layer or an epoxy tape, around the outer circumference of the tubular member 4 and the sheath 14 in multiple layers, and further covering the waterproof tape 51 with a heat shrink tube 52. Note that the waterproofing treatment section 5 is not limited to the one using the waterproof tape 51 and the heat shrink tube 52, and may have other structures.

The insulating plug 61 comprises a molded insulator 611, a high-voltage electrode 612 provided at one end of the insulator 611, and a voltage detector electrode 613 provided at the other end of the insulator 611. The high-voltage electrode 612 is formed with a countersunk hole 612a corresponding to the shape of the nut 100, and a female thread 612b into which a male thread 91a provided on the device-side conductor 91 screws. The voltage detector electrode 613 is formed with a tool fitting hole 613a into which the tip of a tool such as a socket wrench fits. The insulator 611 is molded integrally with the high-voltage electrode 612 and the voltage detector electrode 613.

The protective cap 62 is made of a semiconductive rubber material and is formed in a cylindrical shape with a bottom, having a disk-shaped bottom wall 621 and a cylindrical side wall 622 integrally therewith. The bottom wall 621 covers the insulating plug 61. The side wall 622 has an annular protrusion 622a formed on its inner surface for fixing to the cable holder 3.

The cable holder 3 has a holding tube portion 3A with an insertion hole 20 provided in the center, which holds the central conductor 11 and insulating layer 12 of the power cable 1, and a connecting tube portion 3B which houses the connection portion between the compression terminal 10 and the equipment side conductor 91 of the equipment 9. In this embodiment, the axial direction of the connecting tube portion 3B is perpendicular to the axial direction of the holding tube portion 3A, and the cable holder 3 is formed in a T-shape. Hereinafter, in the axial direction of the holding tube portion 3A (left-right direction in FIG. 1), the connecting tube portion 3B side is referred to as the tip side, and the opposite side (the tubular member 4 side) is referred to as the rear side.

The cable holder 3 has an insulator 30 made of a polymer material, and first to third semi-conductors 31 to 33 made of a polymer material to which a conductive agent has been dispersed to impart conductivity. The insulator 30 is provided across the holding tube portion 3A and the connecting tube portion 3B, and is provided around the insertion hole 20 in the holding tube portion 3A. The insulator 30 in the connecting tube portion 3B is provided with a bushing insertion hole 301 into which the device-side bushing 90 is inserted, and an insulating plug insertion hole 302 into which the insulating plug 61 is inserted. The first to third semi-conductors 31 to 33 are provided integrally with the insulator 30, and reduce the electric field around the power cable 1. The third semi-conductor 33 has a shielding function that prevents the electric field around the power cable 1 from leaking to the outside.

As the polymer-based material of the insulator 30 and the first to third semi-conductors 31 to 33 in the cable holder 3, for example, silicone rubber, ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), etc. can be used. As the conductivity imparting agent, for example, conductive fine powder such as carbon black can be used.

The first to third semi-conductors 31 to 33 are formed by injection molding prior to forming the insulator 30. The first semi-conductor 31 surrounds the compression terminal 10 from the tip end of the retaining tube 3A to the connecting tube 3B. The first semi-conductor 31 is formed with a terminal insertion hole 311 into which the compression terminal 10 is inserted together with a longitudinal portion of the central conductor 11 and the insulating layer 12, and an accommodation hole 312 that accommodates a portion of each of the device-side bushing 90 and the insulating plug 61. The second semi-conductor 32 is disposed closer to the rear end of the retaining tube 3A than the first semi-conductor 31.

The insertion hole 20 is formed by a small diameter hole portion 21 with an inner diameter corresponding to the outer diameter of the insulating layer 12 of the power cable 1, a large diameter hole portion 23 provided at the end portion on the rear end side, and a tapered hole portion 22 whose inner diameter gradually increases from the small diameter hole portion 21 toward the large diameter hole portion 23. A part of the small diameter hole portion 21 on the tip side is formed by a first semi-conductor 31, and a part of the rear end side is formed by a second semi-conductor 32. Between the first semi-conductor 31 and the second semi-conductor 32, the small diameter hole portion 21 is formed by an insulator 30. A manufacturing method of the cable holder 3 will be described later.

Figure 3(a) is a side view of the third semi-conductor 33 as viewed from a direction perpendicular to the axial direction of the retaining tube portion 3A and the axial direction of the connecting tube portion 3B, and Figure 3(b) is a side view of the third semi-conductor 33 as viewed from the rear end side along the axial direction of the retaining tube portion 3A. Figures 3(a) and (b) show the ground wire 71 along with the third semi-conductor 33.

The third semi-conductor 33 integrally comprises a cylindrical portion 331 that covers the insulator 30 around the insertion hole 20 in a portion of the tip side of the holding tube portion 3A including the outer periphery of the first semi-conductor 31, first and second protruding pieces 332, 333 that protrude radially outward from the outer periphery 331a of the cylindrical portion 331, and an outer shell portion 334 that constitutes the outer shell of the connecting tube portion 3B. The outer shell portion 334 is formed in a cylindrical shape so as to cover the insulator 30 in the connecting tube portion 3B. The outer shell portion 334 has an annular recess 334a formed on the outer periphery 334b that engages with the protrusion 622a formed on the side wall 622 of the protective cap 62.

The first protrusion 332 and the second protrusion 333 are provided at symmetrical positions on either side of the insertion hole 20. In other words, the first and second protrusions 332, 333 are provided at positions 180° apart in the circumferential direction of the cylindrical portion 331. The first protrusion 332 has a through hole 332a that penetrates the first protrusion 332. The second protrusion 333 has a through hole 333a that penetrates the second protrusion 333.

In this embodiment, when the third semi-conductor 33 is viewed from a direction perpendicular to the axial direction of the holding tube portion 3A and the axial direction of the connecting tube portion 3B, the first and second protrusions 332, 333 are formed in a triangular shape. However, the shape of the first and second protrusions 332, 333 is not limited to this, and may be, for example, a square or semicircular shape.

An earth wire 71 is connected to the first protrusion 332. The earth wire 71 has an earth wire body 711 made of an insulated electric wire whose core is covered with an insulator, and an earth terminal 712 attached to the tip of the earth wire body 711. The earth terminal 712 is attached to the first protrusion 332 by a bolt 72 and a nut 73. The threaded portion 721 of the bolt 72 is inserted into the through hole 332a of the first protrusion 332.

The earth wire 71 may be connected to the second protrusion 333. In this case, the screw portion 721 of the bolt 72 is inserted into the through hole 333a of the second protrusion 333. When the earth wire 71 is connected to the first protrusion 332, the second protrusion 333 does not need to have a through hole 333a, and when the earth wire 71 is connected to the second protrusion 333, the first protrusion 332 does not need to have a through hole 332a. In other words, it is sufficient that at least one of the first and second protrusions 332, 333 has a through hole that penetrates the protrusion.

The tubular member 4 is fixed to the rear end of the cable holder 3, and passes through the central conductor 11 and insulating layer 12 of the power cable 1, and also houses the shielding layer 13 and part of the sheath 14. The tubular member 4 is made of a metal having high conductivity, such as brass or an aluminum alloy. The multiple shield wires 131 of the shielding layer 13 are led out of the sheath 14 inside the tubular member 4, folded back around the outer periphery of the sheath 14, and led out to the outside of the tubular member 4 from between the outer periphery 14a of the sheath 14 and the inner periphery 4a of the tubular member 4.

Figure 4(a) is a perspective view showing the tubular member 4. Figure 4(b) is a perspective cross-sectional view of the tubular member 4 taken along line B-B in Figure 4(a). The tubular member 4 integrally has an embedded portion 41 embedded in the cable holder 3 and a cylindrical portion 42 exposed from the cable holder 3. The tubular member 4 is fixed to the cable holder 3 by embedding the embedded portion 41 in the insulator 30 of the cable holder 3.

The embedded portion 41 is cylindrical, and has through holes 410 formed in the axial direction at multiple locations (four locations in this embodiment) in the circumferential direction. The insulator 30 fits into the multiple through holes 410. The embedded portion 41 is embedded in the insulator 30 in a portion of the tapered hole portion 22 of the insertion hole 20 and in a portion that corresponds to the outer periphery of the large diameter hole portion 23.

The embedded portion 41 and the cylindrical portion 42 are aligned in the axial direction along the longitudinal direction of the power cable 1 inside the tubular member 4. The cylindrical portion 42 further has a large diameter portion 421 and a small diameter portion 422 with different outer diameters. The large diameter portion 421 is formed continuously with the embedded portion 41. The small diameter portion 422 has an outer diameter smaller than that of the large diameter portion 421, and is formed continuously with the end of the large diameter portion 421 on the opposite side to the embedded portion 41. The waterproof tape 51 of the waterproofing treatment portion 5 is wrapped around the outer peripheral surface 422a of the small diameter portion 422.

The embedded portion 41 is formed to have a smaller outer diameter than the large diameter portion 421 and the small diameter portion 422. The embedded portion 41 is also formed to have a thinner radial thickness than the large diameter portion 421 and the small diameter portion 422. The outer peripheral surface 421a of the large diameter portion 421 is not covered by the insulator 30 of the cable holder 3 and is exposed to the outside. The insulator 30 of the cable holder 3 is in close contact with the outer peripheral surface 41a of the embedded portion 41 and the axial end surface 421b of the large diameter portion 421 on the embedded portion 41 side.

In addition, the tubular member 4 has an earth wire connection portion 401 to which the earth wire 74 is connected, and a shield wire connection portion 402 to which the multiple shield wires 131 are connected, provided on the cylindrical portion 42. The earth wire connection portion 401 is provided in a portion that is not covered by the waterproofing treatment portion 5, and the shield wire connection portion 402 is provided in a portion that is covered by the waterproofing treatment portion 5. In this embodiment, the earth wire connection portion 401 is provided at one circumferential location on the large diameter portion 421, and the shield wire connection portions 402 are provided at multiple circumferential locations on the small diameter portion 422. The earth wire connection portion 401 is part of the large diameter portion 421, and the shield wire connection portions 402 are part of the small diameter portion 422.

Connection terminals 75 are attached to the tips of the multiple shield wires 131. In this embodiment, the number of shield wires 131 in the shielding layer 13 is 20, and 10 of these shield wires 131 are electrically connected to the tubular member 4 by two connection terminals 75. In other words, in this embodiment, two shield wire connection parts 402 are provided on the tubular member 4, and these shield wire connection parts 402 are provided at positions 180° apart in the circumferential direction of the small diameter part 422. The waterproofing treatment part 5 covers the 20 shield wires 131 led out from the tubular member 4 together with the two connection terminals 75.

The two connection terminals 75 are each connected to the shield wire connection part 402 by a bolt 76. The shield wire connection part 402 has a threaded hole 402a into which the bolt 76 for connecting the connection terminal 75 is screwed. In this embodiment, the threaded hole 402a penetrates the small diameter part 422 in the radial direction. However, the threaded hole 402a does not have to penetrate the small diameter part 422. The peripheral part of the opening of the threaded hole 402a on the outer circumferential surface 422a of the small diameter part 422 is a flat surface 402b perpendicular to the central axis of the threaded hole 402a so that the connection of the connection terminal 75 by tightening the bolt 76 is reliably performed.

The earth wire 74 has an earth wire body 741 made of an insulated wire whose core is covered with an insulator, and an earth terminal 742 attached to the tip of the earth wire body 741. The earth wire connection part 401 has a screw hole 401a into which a bolt 77 for connecting the earth terminal 742 is screwed, which opens on the outer circumferential surface 421a of the large diameter part 421 of the tubular member 4 and is formed so as not to penetrate the tubular member 4. The periphery of the opening of the screw hole 401a on the outer circumferential surface 421a of the large diameter part 421 is a flat surface 401b perpendicular to the central axis of the screw hole 401a so that the connection of the earth terminal 742 by tightening the bolt 77 is reliably performed.

As shown in FIG. 4B, the thickness _T1 of the embedded portion 41 in the radial direction of the tubular member 4 is thinner than the thickness _T2 of the earth wire connection portion 401 in the radial direction of the tubular member 4. Here, the thickness _T2 of the earth wire connection portion 401 is the distance between the flat surface 401b in the central axis direction of the screw hole 401a and the inner peripheral surface 4a of the tubular member 4. The thickness _T1 of the embedded portion 41 is thinner than the thickness _T3 of the shield wire connection portion 402 in the radial direction of the tubular member 4. Here, the thickness _T3 of the shield wire connection portion 402 is the distance between the flat surface 402b in the central axis direction of the screw hole 402a and the inner peripheral surface 4a of the tubular member 4. The thickness _T1 of the embedded portion 41 is, for example, half or less of the thickness _T2 of the earth wire connection portion 401. The embedded portion 41 has a thickness _T1 of, for example, 4 to 5 mm, and the earth wire connection portion 401 has a thickness _T2 of, for example, 15 mm.

(Method of Manufacturing the Power Cable Terminal Connection Part 2 and the Cable Holder 3)
Next, a method for manufacturing the power cable terminal connection part 2 and the cable holder 3 will be described with reference to Figures 5 to 9. This manufacturing method includes a semi-conductor molding step for molding the first to third semi-conductors 31 to 33, an arrangement step for arranging the first to third semi-conductors 31 to 33 and the tubular member 4 in a mold, and an insulator molding step for injecting a thermoplastic polymer material into the mold to mold the insulator 30. In the semi-conductor molding step, each of the first to third semi-conductors 31 to 33 is injection molded by injecting a thermoplastic polymer material, in which conductive powder has been dispersed to give conductivity, into the mold.

Figure 5 is an explanatory diagram showing the mold 8 for molding the insulator 30 together with the third semi-conductor 33. The mold 8 has an upper mold 81 and a lower mold 82, first and second columnar molds 83, 84, and a rod-shaped mold 85 which is a rod-shaped mold member for forming the insertion hole 20. The first and second columnar molds 83, 84 and the rod-shaped mold 85 can move forward and backward in a direction perpendicular to the relative movement direction of the upper mold 81 and the lower mold 82.

As an example, the lower die 82 is fixed to a die table, and the upper die 81 moves up and down in a vertical direction relative to the lower die 82. The first and second columnar dies 83, 84 and the rod-shaped die 85 move forward and backward in a horizontal direction relative to the lower die 82. The first columnar die 83 and the second columnar die 84 move along the central axis direction so as to approach and move away from each other, and the rod-shaped die 85 moves in a direction perpendicular to the central axis of the first and second columnar dies 83, 84.

Figure 6 is an explanatory diagram showing the first to third semi-conductors 31 to 33 and the tubular member 4 arranged in the lower mold 82, together with the first and second columnar molds 83, 84 and the rod-shaped mold 85. In Figure 6, the cavity space 80 of the mold 8 into which the molten thermoplastic polymer material is injected is shown by gray shading. Figure 7(a) is a perspective view showing a part of the upper mold 81, and Figure 7(b) is a perspective view showing a part of the lower mold 82.

The bushing insertion hole 301 of the insulator 30 is formed by the first columnar die 83, and the insulating plug insertion hole 302 of the insulator 30 is formed by the second columnar die 84. A part of each of the first and second columnar dies 83, 84 is inserted into the accommodation hole 312 of the first semi-conductor 31, and the first semi-conductor 31 is supported in the mold 8 by the first and second columnar dies 83, 84 and the rod-shaped die 85. The second semi-conductor 32 is supported in the mold 8 by the rod-shaped die 85.

The upper die 81 and the lower die 82 are respectively formed with first recesses 811, 821 and second recesses 812, 822 having shapes corresponding to the half-split shapes of the holding tube portion 3A and the connecting tube portion 3B of the cable holding body 3. The holding tube portion 3A is formed by the first recess 811 of the upper die 81 and the first recess 821 of the lower die 82, and the connecting tube portion 3B is formed by the second recess 812 of the upper die 81 and the second recess 822 of the lower die 82.

The third semi-conductor 33 has a cylindrical portion 331 accommodated in the first recess 811 of the upper die 81 and the first recess 821 of the lower die 82, and an outer shell portion 334 accommodated in the second recess 812 of the upper die 81 and the second recess 822 of the lower die 82. The outer peripheral surface 331a of the cylindrical portion 331 contacts the inner surface 811a of the first recess 811 of the upper die 81 and the inner surface 821a of the first recess 821 of the lower die 82, and the outer peripheral surface 334b of the outer shell portion 334 contacts the inner surface 812a of the second recess 812 of the upper die 81 and the inner surface 822a of the second recess 822 of the lower die 82. When the upper die 81 and the lower die 82 are molded together, the first and second protruding pieces 332, 333 of the third semi-conductor 33 are sandwiched between the upper die 81 and the lower die 82.

As shown in FIG. 7(a), the upper mold 81 is provided with a third recess 813 that accommodates a part of the first protrusion 332 of the third semi-conductor 33, and a fourth recess 814 that accommodates a part of the second protrusion 333 of the third semi-conductor 33, which are connected to the first recess 811. As shown in FIG. 7(b), the lower mold 82 is provided with a third recess 823 that accommodates a part of the first protrusion 332 of the third semi-conductor 33, and a fourth recess 824 that accommodates a part of the second protrusion 333 of the third semi-conductor 33, which are connected to the first recess 821.

The third recesses 813, 823 of the upper die 81 and the lower die 82 accommodate a portion of the first protrusion 332 in the thickness direction. The fourth recesses 814, 824 of the upper die 81 and the lower die 82 accommodate a portion of the second protrusion 333 in the thickness direction. The first protrusion 332 is sandwiched between the bottom surface 813a of the third recess 813 of the upper die 81 and the bottom surface 823a of the third recess 823 of the lower die 82, and the second protrusion 333 is sandwiched between the bottom surface 814a of the fourth recess 814 of the upper die 81 and the bottom surface 824a of the fourth recess 824 of the lower die 82.

The lower mold 82 is provided with a first protrusion 825 that is inserted into the through hole 332a of the first protrusion 332, and a second protrusion 826 that is inserted into the through hole 333a of the second protrusion 333. The first protrusion 825 is erected on the bottom surface 823a of the third recess 823 of the lower mold 82, and the second protrusion 826 is erected on the bottom surface 824a of the fourth recess 824. The length of the first protrusion 825 and the second protrusion 826 is, for example, a length equivalent to the thickness of the first protrusion 332 and the second protrusion 333.

In addition, instead of the first protrusion 825 and the second protrusion 826 of the lower die 82, a protrusion to be inserted into the through hole 332a of the first protrusion 332 and a protrusion to be inserted into the through hole 333a of the second protrusion 333 may be provided on the upper die 81. Also, a protrusion to be inserted into the through hole 332a of the first protrusion 332 may be provided on one of the upper die 81 and the lower die 82, and a protrusion to be inserted into the through hole 333a of the second protrusion 333 may be provided on the other of the upper die 81 and the lower die 82.

In the insulator molding process, the first and second protrusions 332, 333 are sandwiched between the upper mold 81 and the lower mold 82, and the first and second protrusions 825, 826 are inserted into the through holes 332a, 333a of the first and second protrusions 332, 333. A molten thermoplastic polymer material is injected into the cavity space 80 in the mold 8. This thermoplastic polymer material solidifies to become the insulator 30, thereby obtaining a cable holder 3 with the tubular member 4 fixed to its end. The thermoplastic polymer material also enters the multiple through holes 410 formed in the embedded portion 41 of the tubular member 4, preventing the tubular member 4 from coming loose.

As shown in FIG. 6, the rod-shaped mold 85 is integrally formed with a tip portion 851 that is disposed within the terminal insertion hole 311 of the first semi-conductor 31, a small diameter shaft portion 852 that is disposed in the portion that will become the small diameter hole portion 21 of the insertion hole 20, a tapered shaft portion 853 that is disposed in the portion that will become the tapered hole portion 22 of the insertion hole 20, a medium diameter shaft portion 854 that is disposed in the portion that will become the large diameter hole portion 23 of the insertion hole 20, and a large diameter shaft portion 855 that is disposed inside the cylindrical portion 42 of the tubular member 4.

Figure 8(a) is an explanatory diagram showing the tubular member 4 and its surroundings in the placement process. In Figure 8(a), the small diameter shaft portion 852, tapered shaft portion 853, medium diameter shaft portion 854, large diameter shaft portion 855, and O-ring 86 are shown in cross section in the portion above the central axis C of the rod-shaped mold 85. Figure 8(b) is an explanatory diagram showing the state when the rod-shaped mold 85 is being removed from the cable holder 3 and the tubular member 4 after the insulator 30 has been formed. Figure 9 is an enlarged view showing a portion of Figure 8(a).

The large diameter shaft portion 855 has an annular groove 855b formed on the outer peripheral surface 855a of the end portion on the medium diameter shaft portion 854 side in the axial direction. An O-ring 86 is housed in this annular groove 855b as an annular elastic body. The O-ring 86 elastically contacts the inner peripheral surface 42a of the cylindrical portion 42 of the tubular member 4, and prevents the thermoplastic polymer material from flowing beyond the O-ring 86 to the small diameter portion 422 side.

An annular step 423 is formed on the inner peripheral surface 42a of the cylindrical portion 42. As shown in FIG. 8B, the inner diameter _D1 of the portion closer to the embedded portion 41 than the step 423 is smaller than the inner diameter D2 of the portion closer to the embedded portion 41 than the step 423, and is slightly larger than the outer diameter _D3 of the large diameter shaft portion 855. The annular groove 855b of the rod-shaped mold 85 is formed on the outer peripheral surface 855a of the large diameter shaft portion 855 at the portion disposed closer to the embedded portion 41 than the step 423 in the disposing step _. Hereinafter, the inner peripheral surface 42a of the cylindrical portion 42 at the portion closer to the embedded portion 41 than the step 423 is referred to as the small diameter inner peripheral surface 42b, and the inner peripheral surface 42a of the cylindrical portion 42 at the portion opposite to the embedded portion 41 than the step 423 is referred to as the large diameter inner peripheral surface 42c.

In the placement step and the insulator molding step, the O-ring 86 is compressed in the annular groove 855b in the radial direction of the large diameter shaft portion 855 and elastically contacts the small diameter inner circumferential surface 42b. The difference between the inner diameter _D1 of the small diameter inner circumferential surface 42b of the cylindrical portion 42 and the outer diameter _D3 of the large diameter shaft portion 855 is a dimension that can prevent the thermoplastic polymer material from entering the gap between the small diameter inner circumferential surface 42b and the outer circumferential surface 855a of the large diameter shaft portion 855, but the O-ring 86 elastically contacts the small diameter inner circumferential surface 42b, thereby reliably preventing the thermoplastic polymer material from flowing toward the small diameter portion 422 side from the O-ring 86.

When the rod-shaped mold 85 is pulled out from the cable holder 3 and the tubular member 4, the O-ring 86 slides on the small diameter inner circumferential surface 42b. When the O-ring 86 passes the step 423, the O-ring 86 faces the large diameter inner circumferential surface 42c, and the amount of compression of the O-ring 86 is alleviated, and the frictional force generated between the O-ring 86 and the tubular member 4 is reduced. This allows the rod-shaped mold 85 to be easily pulled out and reduces wear on the O-ring 86. Also, when inserting the rod-shaped mold 85 inside the tubular member 4 in the arrangement process, the insertion work of the rod-shaped mold 85 is made easier and wear on the O-ring 86 can be reduced.

(Functions and Effects of the Embodiments)
According to the embodiment described above, the annular step 423 is formed on the inner circumferential surface 42a of the cylindrical portion 42 of the tubular member 4, and the inner diameter D2 of the large diameter inner circumferential surface 42c is larger than the inner diameter _D1 of the small diameter inner circumferential surface 42b on the embedded portion ₄₁ side of the step 423, so that the rod-shaped die 85 can be easily inserted and removed from the tubular member 4, improving workability during manufacturing. In addition, the rod-shaped die 85 integrally has the small diameter shaft portion 852, the tapered shaft portion 853, the medium diameter shaft portion 854, and the large diameter shaft portion 855, so that the small diameter hole portion 21, the tapered hole portion 22, and the large diameter hole portion 23 of the insertion hole 20 can be easily formed.

(Summary of the embodiment)
Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[1] A power cable termination connection part (2) to which a termination part of a power cable (1) is connected, the power cable (1) having a central conductor (11), an insulating layer (12) covering the outer periphery of the central conductor (11), a shielding layer (13) consisting of a plurality of shield wires (131) arranged to surround the outer periphery of the insulating layer (12), and a sheath (14) covering the outer periphery of the shielding layer (13), the power cable termination connection part (2) comprising: a cable holder (3) having an insertion hole (20) into which the central conductor (11) and the insulating layer (12) of the power cable (1) are inserted; and a cable holder (3) fixed to an end of the cable holder (3), which passes through the central conductor (11) and the insulating layer (12) and accommodates a part of the shielding layer (13) and the sheath (14). and a metal tubular member (4) having an insulating material (12) formed from a polymer-based material and a semi-conductor (31-33) formed from a polymer-based material to which conductivity has been imparted by a conductivity imparting agent, the tubular member (4) having an embedded portion (41) embedded in the cable holder (3) and a cylindrical portion (42) exposed from the cable holder (3), the embedded portion (41) and the cylindrical portion (42) are aligned in an axial direction along the longitudinal direction of the power cable (1), the cylindrical portion (42) has an annular step portion (423) formed on an inner circumferential surface (42a), and an inner diameter (D ₁ ) of a portion on the embedded portion (41) side relative to the step portion (423) is smaller than an inner diameter (D ₂ ) of a portion on the opposite side to the embedded portion (41) relative to the step portion (423).

[2] A method for manufacturing the power cable terminal connection part (2) described in [1] above, comprising an insulator molding step of injection-molding the insulator (30) of the cable holder (3) using a rod-shaped mold member (85) inserted inside the tubular member (4), the rod-shaped mold member (85) has an annular groove (855b) formed on the outer circumferential surface (855a) of a portion disposed closer to the embedded part (41) than the step portion (423) in the insulator molding step, a ring-shaped elastic body (86) is accommodated in the ring-shaped groove (855b), and the elastic body (86) elastically contacts the inner circumferential surface (42b) of the cylindrical part (42) on the embedded part (41) side closer to the step portion (423).

[3] The method for manufacturing the power cable terminal connection part (2) described in [2] above, in which the rod-shaped member (85) integrally has a small diameter shaft part (852) that is arranged in the part that becomes the insertion hole (20) and a large diameter shaft part (855) that is arranged inside the cylindrical part (42).

Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the embodiments described above. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention.

REFERENCE SIGNS LIST 1...power cable 11...central conductor 12...insulating layer 13...shielding layer 14...sheath 2...power cable termination connection portion 20...insertion hole 3...cable holder 30...insulator 31-33...first to third semi-conductors 4...tubular member 41...embedded portion 42...cylindrical portion 42a...inner circumferential surface 85...rod-shaped (rod-shaped member) 852...small diameter shaft portion 855...large diameter shaft portion 86...O-ring (elastic body)

Claims (3)

A power cable termination connection part to which a termination part of a power cable is connected, the termination part having a central conductor, an insulating layer covering an outer periphery of the central conductor, a shielding layer consisting of a plurality of shield wires arranged to surround an outer periphery of the insulating layer, and a sheath covering the outer periphery of the shielding layer,
a cable holder having an insertion hole into which the central conductor and the insulating layer of the power cable are inserted;
a metal tubular member that is fixed to an end of the cable holder, through which the central conductor and the insulating layer pass and that houses the shielding layer and a portion of the sheath,
The cable holder includes an insulator made of a polymeric material and a semi-conductor made of a polymeric material to which electrical conductivity is imparted by an electrical conductivity imparting agent,
the tubular member has an embedded portion embedded in the cable holder and a cylindrical portion exposed from the cable holder, the embedded portion and the cylindrical portion being aligned in an axial direction along a longitudinal direction of the power cable,
the cylindrical portion has an annular step formed on an inner circumferential surface thereof, and an inner diameter of a portion of the cylindrical portion closer to the embedded portion than the step is smaller than an inner diameter of a portion of the cylindrical portion closer to the embedded portion than the step.
Power cable termination connections. A method for manufacturing the power cable terminal connection part according to claim 1, comprising the steps of:
an insulator molding step of injection-molding the insulator of the cable holder using a rod-shaped mold member that is inserted into the inside of the tubular member;
an annular groove is formed on an outer peripheral surface of a portion of the rod-shaped mold member that is disposed on the embedded portion side relative to the step portion in the insulator molding process, and an annular elastic body is accommodated in the annular groove;
the elastic body is in elastic contact with an inner circumferential surface of the cylindrical portion on the embedded portion side relative to the step portion;
A method for manufacturing a power cable termination. The rod-shaped member integrally includes a small diameter shaft portion disposed in the portion that becomes the insertion hole, and a large diameter shaft portion disposed inside the cylindrical portion.
The method for manufacturing a power cable terminal connection part according to claim 2 .