JP2014075247A - Water-blocking cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress damage and maintain water-blocking performance by mitigating stress due to bending through deformation of shortening in the inside and lengthening in the outside of the convex and concave section of a water-blocking tape layer when a cable is bent.SOLUTION: Over a cable core 17 constituted of a conductor 11, an insulation layer 13 and so on, a spacer layer 18, a water-blocking tape layer 19 and a sheath layer 20 are laminated in order. As the spacer layer 18, a string-like spacer 18a with its cross section of a half cycle is wrapped spirally and closely over the cable core 17. As the water-blocking tape layer 19 over the spacer layer 18, a water-blocking tape 19a of width wider than the circumference is arranged longitudinally along the longitudinal direction of the spacer layer 18 and rounded tubularly in the circumferential direction for covering, the edges of the water-blocking tape 19a being overlapped to each other. A roller R is applied over the water-blocking tape 19a to follow the spiral shape of the spacer layer 18, and the water-blocking tape layer 19 is shaped to be spiral, following the surface shape of the spacer layer 18.

Description

  The present invention relates to a water shielding cable that prevents water from entering the inside of a power cable, a control cable, and a communication cable and has improved reliability as a cable.

  For example, as shown in FIG. 11A, for example, as a water shielding cable, an inner semiconductive layer 2, an insulator layer 3, an outer semiconductive layer 4, a shielding copper tape 5, A laminate in which a pressing tape 6, an aluminum water shielding layer 7 and a sheath layer 8 are laminated is known. Further, as shown in FIG. 11B, the aluminum water-impervious layer 7 includes a conductive plastic layer 7a, an aluminum foil 7b, a plastic layer 7c, and an adhesive layer 7d from the lower layer.

  Patent Documents 1 to 3 also describe preventing water from entering the cable by winding a water shielding tape.

JP-A-8-329741 JP 2005-327549 A JP 2008-71641 A

  However, when the cable is laid, if the water shielding cable is bent, wrinkles occur in the aluminum foil 7b of the aluminum water shielding layer 7 depending on the degree of bending. In the state where the wrinkles are generated, if a heat cycle is applied to the conductor 1 or due to temperature fluctuation, an expansion and contraction stress is generated in the cable. Due to this expansion and contraction, cracks and tears occur at the wrinkle generating portion of the aluminum foil 7b, and the water shielding performance is significantly impaired.

  An object of the present invention is to provide a water shielding cable that solves the above-described problems and that can prevent water infiltration even when the bending is large and that prevents water from being damaged.

  In order to achieve the above object, a water-impervious cable according to the present invention includes a spacer layer made of a synthetic resin formed in an outer layer of a cable core including a conductor and an insulator layer, and the outer circumferential section in the longitudinal direction is formed in a wave shape. A water shielding tape layer is provided on the outer surface of the spacer layer, and a sheath layer made of resin is coated on the water shielding tape layer.

  According to the waterproof cable according to the present invention, when the cable is bent, the concave and convex portions of the waterproof tape layer are contracted on the inside and the outside is extended, so that stress due to bending is relieved to prevent damage to the waterproof tape layer. , Can keep water shielding performance.

It is sectional drawing which peeled off the edge part of the impermeable cable of Example 1. FIG. It is a perspective view of a string-like spacer. It is sectional drawing of a water shielding tape. It is sectional drawing which peeled off the edge part of the impermeable cable of Example 2. FIG. It is a perspective view of the string-like spacer for embedding. It is explanatory drawing of the state which winds the water shielding tape with a spacer on the cable core of Example 3. FIG. It is sectional drawing which peeled off the edge part of the water-impervious cable of Example 4. 10 is a perspective view in which a spacer layer is formed on a cable core of Example 5. FIG. It is a front view of an extrusion die. It is sectional drawing which peeled off the step which formed the water shielding tape layer on the spacer layer. It is sectional drawing which peeled off the edge part of the conventional water shielding cable, and sectional drawing of a water shielding tape.

  The present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is a cross-sectional view of an end portion of a water-shielding cable according to Example 1 that has been stripped. For example, around a conducting wire 11 formed by twisting 91 2.9φ annealed copper wires, a 1.0 mm thick inner semiconductive layer 12, a 6 mm thick insulator layer 13, and a 1.0 mm thick outer A semiconductive layer 14, a shielding copper tape layer 15 having a thickness of 0.1 mm, and a semiconductive tape layer 16 are laminated, and a cable core 17 having an outer diameter of 46 mm, for example, is formed. On the cable core 17, a spacer layer 18, a water shielding tape layer 19, and a sheath layer 20 are sequentially laminated.

  Such a structure of the spacer layer 18 and the like on the cable core 17 is not limited to a power cable, but for a cable whose characteristics are damaged by water immersion such as a communication and control cable (optical cable, coaxial cable, twisted pair cable, etc.). It can be applied in the same form.

  The copper tape layer 15 is wrapped and wrapped with a copper tape at 1/4 pitch, and the semiconductive tape layer 16 is wrapped with a semiconductive tape stacked at 1/4 pitch.

  As shown in FIG. 2A, the spacer layer 18 is formed of a synthetic resin string spacer 18a having a semicircular cross section having a height of 2 mm and a base width of 8 mm. It is formed by tightly winding. This string-like spacer 18a is kneaded with about 20% of EVA resin, has semiconductive properties, and is molded by extrusion.

  As shown in FIG. 2B, the string-like spacer 18a is inserted with a high-strength core material 18b such as iron or SUS or a thin metal wire or aramid fiber in consideration of the leadability and recyclability. It is preferable to do. These string-like spacers 18a are not a single wire, but may be a plurality of the spacers arranged in parallel as shown in FIG. 2 (c), for example.

  In the case of a power cable, a high voltage is applied. Therefore, in order to avoid discharge between the cable core 17 and the water shielding tape layer 19, the string spacer 18a has a semiconductive property as in the embodiment. preferable.

  Further, as the water shielding tape layer 19 for providing a water shielding function on the spacer layer 18, a water shielding tape 19 a having a width of about 20 mm wider than the circumference is vertically arranged in the longitudinal direction on the spacer layer 18. The spacer layer 18 is covered by rounding into a cylindrical shape in the circumferential direction, and the edges of the water shielding tape 19a are overlapped.

  In the case of a power cable, as shown in FIG. 3A, the water shielding tape 19a is, for example, a semiconductive layer 19b having a thickness of 0.1 mm and a metal layer 19c of an aluminum foil having a thickness of 0.1 mm. It consists of a 1 mm thick reinforcing layer 19d and a 0.1 mm thick adhesive layer 19e. The communication and control cable is composed of a 0.1 mm thick metal layer 19f and a 0.1 mm thick adhesive layer 19g as shown in FIG. 3 (b). The thickness of the water shielding tape 19a to be used is preferably 0.1 to 0.8 mm. If the thickness is thinner than 0.1 mm, it is too soft to hold the shape, and if it is thicker than 0.8 mm, it is rigid. Therefore, the adhesive part may be peeled off when the cable is bent.

  While rotating the plurality of rollers R shown in FIG. 1 along the spiral shape of the spacer layer 18, the rollers R are relatively moved on the water shielding tape 19 a to form the spiral shape following the uneven shape of the spacer layer 18. At this time, the adhesive layer 19e or 19g where the edges of the water shielding tape 19a overlap with each other is heated with an industrial dryer, and is adhered so that there is no water leakage while being pressed by the roller R, and the upper layer is made of, for example, PVC resin. By covering the sheath layer 20 having a thickness of 3.5 mm, the water shielding cable is completed.

  FIG. 4 is a cross-sectional view of the water shielding cable of the second embodiment. The same reference numerals as those in FIG. 1 denote the same members as those in the first embodiment, and the dimensions are the same as those in the first embodiment.

  As shown in FIG. 5, a string-like embedding string spacer 21 made of PVC resin having a circular cross section with a radius of 4 mm is wound along the valley portion 19h of the water shielding tape layer 19 formed of the water shielding tape 19a. Thus, the valley portion 19h is filled so that the difference between the peaks and valleys of the water shielding tape layer 19 is reduced.

  The embedded string spacer 21 serves to prevent the water shielding tape layer 19 from being bent with a small curvature when the cable is bent. The embedded string spacer 21 wound around the valley portion 19h serves as a cushioning material for relaxing the compressive force applied to the water shielding tape layer 19 at the time of bending. Is preferred.

  A PVC resin is covered as a sheath layer 20 on the water-impervious tape layer 19 configured as described above in the same manner as in the first embodiment.

  FIG. 6 is an explanatory view showing a state in which a water shielding tape with a spacer is wound around a cable core in the water shielding cable of Example 3. The spacer layer and the impermeable tape layer 22 are formed by winding the impermeable tape with spacer 22a on the cable core 17 in a spiral shape, and the spacer layer and the impermeable tape layer 22 are formed simultaneously.

  This water-impervious tape 22a with a spacer forms, for example, a concavo-convex portion having a cross-section bellows having five ridges at equal intervals along the longitudinal direction of a tape material having a width of 45 mm. A plurality of string-like spacers 18a each having a length of 2 mm and a base of 8 mm are bonded in advance to the inside of the four peaks except for one peak at the end by thermal fusion or an adhesive. Also, the string-like spacer 18a in this case can also be used in which an aramid fiber of 2840 denier, for example, is arranged at the center of the inside as shown in FIG. 2 (b).

  When winding the water-impervious tape 22a with a spacer on the cable core 17, the ridge portion of the water-impervious tape 22a with a spacer, on which the string-like spacer 18a is not disposed, The crest of the spacer 18a is covered, and one crest of the water shielding tape 22a overlaps. As a result, the spacer layer and the water-impervious tape layer 22 are formed such that four crests are formed in a spiral shape every round. The adhesive layer at the overlapping portion of the wrap winding of the water-impervious tape with spacer 22a is heated and fused with an industrial dryer, and the sheath layer 20 is provided thereon.

  FIG. 7 is a cross-sectional view of the water shielding cable of the fourth embodiment. On the cable core 17, as in the third embodiment, the spacer layer and the water shielding tape layer 22 are provided by the water shielding tape 22 a with a spacer. A trough is embedded by winding a string-like embedding string spacer 21 having a circular cross section with a radius of 4 mm shown in FIG. 5 along the trough of the water shielding tape layer 22. The sheath layer 20 is formed on the water shielding tape layer 22 and the embedment string spacer 21 as in the other embodiments.

  In Example 4, as in Example 2, the difference between the peaks and valleys of the water shielding tape layer 22 is reduced, and the water shielding cable is difficult to bend.

  FIG. 8 is a perspective view in which a spacer layer is formed on the cable core of the water shielding cable of Example 5. A spacer layer 23 made of a semiconductive resin having spiral protrusions is formed on the cable core 17 by extrusion molding.

  The extrusion die 24 for forming the spacer layer 23 has, for example, 16 semicircular mold parts 24a as shown in FIG. 9, and resin is rotated while the cable core 17 and the extrusion die 24 are relatively rotated. By extruding from the mold part 24 a, 16 concentric protrusions having a petal shape are formed on the cable core 17.

  On the spacer layer 23 formed in this manner, as shown in FIG. 10, in the same manner as in Example 1, a water shielding tape 19a is vertically attached to form a cylindrical shape, and the spiral trough portion of the spacer layer 23 is formed. The water shielding tape 19a is traced with the roller R so as to be along, and at the same time, the concave and convex portions are formed on the water shielding tape 19a while adhering the adhesive layer at the overlapping portion, thereby forming the water shielding tape layer 19. The sheath layer 20 is covered on the waterproof tape layer 19 to complete the waterproof cable. The water shielding tape 19a may be wound while being wrapped about 15 mm on the spacer layer 23 instead of vertically. In Example 5 as well, the string-like spacers 21 for embedding can be embedded in the valleys of the water shielding tape layer 19.

  About the water shielding cable of Examples 1-5 manufactured in this way, the comparative verification by the conventional cable and a bending test was performed. The cable core, the water shielding tape layer, and the sheath layer have the same dimensions as those in the first embodiment.

  Table 1 shows the result of disassembling and observing the cable to compare whether or not wrinkles are generated in the water shielding tape layer with respect to the bending diameter of the cable.

Table 1
Cable bending diameter Conventional product Example 1 Example 2 Example 3 Example 4 Example 5
1000mm ○ ○ ○ ○ ○ ○
500mm × ○ ○ ○ ○ ○
400mm × ○ ○ ○ ○ ×
300mm × × ○ × ○ ×
○: No wrinkles in the water-insulating tape layer, ×: Wrinkles in the water-insulating tape layer

  As can be seen from Table 1, the water shielding cable of the present invention is smaller than the conventional product when the cable is bent. It was found that is difficult to occur.

  On the other hand, for conventional cables, the water shielding tape layer is a cylindrical rigid body, so the inner side is compressed against bending, and the water shielding tape layer buckles without escaping as the water shielding tape layer meanders. There are wrinkles in the layer.

  Further, in Examples 2 and 4 in which the embedded string-like spacers 21 made of a flexible resin are inserted along the valley portions of the water shielding tape layers 19 and 22 during bending, the embedded string-like spacers 21 are provided in the valley portions. It was found that wrinkles were more unlikely to occur when compared with Examples 1 and 3 where insertion was not performed. In this case, it is considered that the soft embedding string spacer 21 plays a role of a cushioning material by bending and relaxes the stress applied to the water shielding tape layers 19 and 22.

  In the first to fifth embodiments, the spacer layers 18 and 23 are provided on the cable core 17 in a spiral shape, but may be formed in a bellows shape.

DESCRIPTION OF SYMBOLS 11 Conductor 12 Internal semiconductive layer 13 Insulator layer 14 External semiconductive layer 15 Copper tape layer 16 Semiconductive tape layer 17 Cable core 18, 23 Spacer layer 18a String-like spacer 19, 22 Water shielding tape layer 19a Water shielding tape 20 Sheath Layer 21 Embedding string spacer 22a Water shielding tape with spacer

Claims (8)

  The outer layer of the cable core including the conductor and the insulator layer is formed with a synthetic resin spacer layer having a wavy cross section in the longitudinal direction, and a water shielding tape layer is provided on the spacer layer following the outer shape of the spacer layer. A water shielding cable, wherein a sheath layer made of resin is coated on the water shielding tape layer.   The water-impervious cable according to claim 1, wherein the spacer layer is formed by winding a string-like spacer spirally around the cable core.   The water shielding cable according to claim 2, wherein a core material made of a fine metal wire or high strength fiber is inserted as a core material into the string spacer.   A spacer-coated water-impervious tape formed by bonding a plurality of string-like spacers at equal intervals along the longitudinal direction of the water-shielding tape to form a concavo-convex portion is arranged on the cable core so that the concavo-convex portions of the portions overlap each other. The water shielding cable according to claim 1, wherein the spacer layer and the water shielding tape layer are formed by being wound in a spiral direction.   By rotating the extrusion mold relatively and extruding a synthetic resin in a petal shape with a cross section concentrically on the cable core, the spacer layer is formed in a spiral shape, and the water shielding layer is formed on the spacer layer. The water shielding cable according to claim 1, wherein a water shielding tape layer is formed by vertically attaching or winding the tape.   The shielding string according to any one of claims 1 to 5, wherein an embedded string spacer made of a synthetic resin material is disposed along a trough having a corrugated cross section of the waterproof tape layer. Water cable.   The water shielding cable according to any one of claims 1 to 6, wherein the spacer layer is made of a semiconductive resin.   The water-insulating tape forming the water-insulating tape layer comprises a metal layer and an adhesive layer, or a metal layer, a reinforcing layer, and an adhesive layer, according to any one of claims 1 to 7. Impervious cable.

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