JP2013037970A - Cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cable which can facilitate extrusion molding of a sheath while satisfactorily maintaining ease of operation for skinning the sheath.SOLUTION: A sheath 5 is extrusion-molded from a foamable resin composition, and has a recessed part 7 configured to bury a stripe 6. The stripe 6 is extrusion-molded from an unfoamable resin composition, and is disposed so as to be peelable from the sheath 5. The recessed part 7 of the sheath 5 has a cross-sectional shape that forms a square part 10 on a sheath outer surface 8 side, and forms a triangle part 11 being continuous with the square part 10 and located closer to a sheath inner surface 9. An apex 12 of the triangle part 11 is oriented toward the sheath inner surface 9.

Description

  The present invention relates to a cable formed by covering an insulated wire core including a conductor and an insulator covering the conductor with a sheath.

  Conventionally, cables such as VVF (600 V vinyl insulated vinyl sheath cable flat type) have been used for indoor electrical wiring. In the VVF, an insulating wire core is formed by coating an insulator made of vinyl chloride resin on each of two conductors, and this insulating wire core is placed in parallel and covered with a sheath made of vinyl chloride resin. ing. When connecting an electrical device or the like, such a cable is first peeled off by cutting the sheath at the end of the cable with a cutter, etc., then exposing and separating each insulated conductor, and finally exposing only the conductor. Work is being done. In addition, when performing indoor cable laying work, it is often laid so as to be along a narrow space such as a ceiling or a wall.

  In general, it is known that the peeling operation as described above becomes easier as the sheath itself is made of a soft material. However, if the sheath itself is too soft, it will be easily worn, resulting in a problem with the mechanical strength of the cable.

  Patent Document 1 below discloses a cable in which a sheath is made of a material having a hardness lower than that of a stripe to facilitate a peeling operation. Specifically, an insulation wire core including a conductor and an insulator covering the conductor is covered with a sheath, and a stripe extending straight along the cable axis is provided. The stripe is made of a material having a hardness higher than that of the sheath, and is formed so as to have a base portion embedded so as to form a groove in the sheath and a protruding portion that is coupled to the base portion and protrudes from the sheath surface. A plurality of sheaths are provided over the entire circumference of the sheath. The arrangement of the stripes is an arrangement in which the sheath surface of the adjacent protruding portion can be used as a sheath cut portion for cutting the sheath, and the tangent line between the adjacent protruding portions can be drawn. . According to this disclosed technology, the sheath is less likely to be worn while improving the workability of the peeling operation.

JP 2010-27416 A

  By the way, although the cable disclosed in Patent Document 1 has a shape that improves the peelability of the sheath, such a shape requires many grooves and stripes to be formed in the sheath. However, it is difficult to extrude the sheath.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cable capable of facilitating extrusion molding of a sheath while maintaining good peelability of the sheath.

  In order to solve the above-mentioned problems, the cable of the present invention according to claim 1 is formed by covering a sheath with one or a plurality of insulated wire cores each including a conductor and an insulator covering the conductor. In the cable having a stripe extending straight along the cable axis, the sheath is extruded from a resin composition having foamability and forms a recess for embedding the stripe, and the stripe has foamability. The concave portion of the sheath is formed so as to be peelable from the sheath, and the concave portion of the sheath forms a quadrangular portion on the outer surface side of the sheath, and the inner surface of the sheath continues to the quadrangular portion. A triangular part is formed on the side, and the apex of the triangular part is formed so as to face the inner surface of the sheath.

Cable According to a second aspect of the invention, in the cable according to claim 1, the overall thickness of the sheath t, t ₁ the height of the triangular portion of the recess formed in the _sheath, the When the angle of the apex of the triangular portion is θ, t / 4 ≦ t ₁ ≦ 3t and π / 4 ≦ θ ≦ π / 2.

  The cable of the present invention according to claim 3 is the cable according to claim 1 or 2, wherein the thickness from the apex of the triangular portion formed in the concave portion of the sheath to the inner surface of the sheath is 0.2 to It is characterized by being 0.4 mm.

  According to the first aspect of the present invention, there is an effect that the extruding of the sheath can be facilitated while maintaining good peeling workability of the sheath.

  According to the second aspect of the present invention, there is an effect that the shape of the sheath can be easily formed.

  According to the third aspect of the present invention, there is an effect that the peelability of the sheath becomes better.

It is a figure which shows the perspective sectional view which shows one Embodiment of the cable of this invention. FIG. 2 is an enlarged cross-sectional view in a state in which a stripe of a portion A in FIG. It is an expanded sectional view of the state which stripped off the stripe of the part A in FIG. It is sectional drawing which shows other embodiment of the cable of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective cross-sectional view showing an embodiment of a cable of the present invention. FIG. 2 is an enlarged sectional view of a portion A in FIG. FIG. 3 is an enlarged cross-sectional view of the recess in FIG. 2 and the stripe peeled off from the recess.

  In the following description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to use, purpose, specifications, and the like. To do.

  In FIG. 1, reference numeral 1 indicates a cable of the present invention. The cable 1 includes, for example, a single insulated wire core 4, a sheath 5 that covers and protects the outer periphery of the insulated wire core 4, and a stripe 6 provided on the sheath 5, and has a substantially circular cross section ( It is assumed to be an example). Hereinafter, first, each component of the cable 1 will be described in detail.

  The insulated wire core 4 includes a conductor 2 and an insulator 3 that covers the outer periphery of the conductor 2. The conductor 2 is formed by twisting strands made of a metal material such as copper, copper alloy, or aluminum into a shape having a substantially circular cross section (the material is an example. Known materials used for conductors). Those appropriately selected from metal materials may be used). The insulator 3 is formed of an insulating polyvinyl chloride resin (the material is an example. An appropriate material selected from known coating materials may be used). The insulator 3 is provided to have a predetermined thickness that can protect the conductor 2. That is, the insulated wire core 4 is in a state where the conductor 2 is protected by the insulator 3.

  The sheath 5 is a covering member that is coated on the outer periphery of the insulating core 4 and has an insulating property and is formed of a foamed polyvinyl chloride resin (a material is an example). A material appropriately selected from known coating materials is used, and this is foamed (a specific example will be described later). The sheath 5 is formed to have a predetermined thickness t (see FIG. 3) that can protect the insulated wire core 4. The sheath 5 is adjusted to a hardness that can protect the insulated wire core 4 and that can be torn by hand at a concave portion 7 described later. The sheath 5 is formed so as to be able to reliably protect the insulated wire core 4 and to perform a peeling operation to expose the insulated wire core 4 inside. Further, the material used can be reduced by foaming the sheath 5.

  As shown in FIG. 2, a recess 7 is formed on the sheath outer surface 8, and a stripe 6 is embedded in the recess 7. As shown in FIG. 3, the recess 7 has a cross-sectional shape in which a square portion 10 is formed on the sheath outer surface 8 side. A triangular portion 11 is formed on the sheath inner surface 9 side continuously to the rectangular portion 10. The apex 12 of the triangular portion 11 is formed so as to face the sheath inner surface 9 side.

  When the concave portion 7 is formed in a shape having only a triangular cross section, if the angle θ of the apex 12 is large, the load is dispersed and the tear load becomes large. Therefore, it is necessary to make the angle θ an acute angle in consideration of tearability. However, if the angle θ is too acute, the triangular portion 11 may be crushed by the pressure of the resin when the sheath 5 is pushed out.

  However, by forming the concave portion 7 having the quadrangular portion 10 and the triangular portion 11 as in the present invention, the optimal angle θ (see FIG. 3) of the apex 12 of the triangular portion 11 that does not cause the above-described collapse can be formed.

As shown in FIG. 3, the dimensions of the sheath 5 and the recess 7 are defined as the thickness from the apex 12 of the triangular portion 11 to the sheath inner surface 9 (hereinafter referred to as the sheath portion minimum thickness) d, and the angle of the apex 12 of the triangular portion 11. Is the thickness t from the sheath outer surface 8 to the sheath inner surface 9, the height of the triangular portion 11 of the recess 7 is t ₁ , the height t from the sheath outer surface 8 to the sheath inner surface 9 and the height t of the triangular portion 11 ₁ and the numerical value of the difference between the sheath portion minimum thickness d and t _2, when the width D of the portion corresponding to the sheath outer surface 8 of the recess 7 and a t × tan (θ / 2) , t 1, a theta t / It is desirable that 4 ≦ t ₁ ≦ 3t and π / 4 ≦ θ ≦ π / 2. By forming the triangular portion 11 with such dimensions, the triangular portion 11 is less likely to be crushed by the pressure of the resin when the sheath 5 is pushed out. Accordingly, the angle θ of the apex 12 of the triangular portion 11 having a desired acute angle can be formed. By forming the angle θ of the apex 12 of the triangular portion 11 at an acute angle, the tear load is reduced. The sheath portion minimum thickness d is preferably 0.2 to 0.4 mm (the reason why it is set to 0.2 to 0.4 mm will be described later). By setting the dimensions in this way, it becomes easy to tear the sheath 5 at the portion of the sheath portion minimum thickness d with a small tear load.

  As shown in FIG. 3, the stripe 6 is formed of a polyvinyl chloride resin that has insulating properties and does not have foamability (the material is an example. From a known coating material). Those appropriately selected may be used). The stripe 6 is molded from a resin composition that does not foam, and the sheath 5 is molded from a foamable resin composition, thereby reducing the area where the stripe 6 is in close contact with the sheath 5 and peeling the stripe 6 from the sheath 5. It can be made easier. The entire stripe 6 is provided so as to be embedded in the recess 7 of the sheath 5. In this embodiment, the number of stripes 6 provided on the sheath 5 is two or four in consideration of the peelability of the sheath 5 (assumed to be an example). The stripe 6 is formed so as to extend straight along the cable axis and over the entire length of the cable. The stripe 6 is formed so that the cross-sectional shape has a quadrangular portion 10 ′ on the sheath outer surface 8 side, and has a triangular portion 11 ′ on the sheath inner surface 9 side continuous with the quadrangle portion 10 ′. Further, the cross-sectional shape of the stripe 6 is such that a portion corresponding to the sheath outer surface 8 in the quadrangular portion 10 ′ is formed in a gentle arc shape. In a state where the stripe 6 is embedded in the sheath 5, the entire cable is formed in a circular cross section.

  The arrangement of the stripes 6 in this embodiment is such that one sheath 6 is provided on the sheath outer surface 8 and the other stripe 6 is disposed on the sheath outer surface 8 on the opposite side of the cable diameter direction from the one stripe 6 (an example). ).

  Then, an example of the manufacturing method of the cable 1 which has each structure and structure mentioned above is demonstrated.

  First, as a first step, the cable 1 is manufactured by extruding the sheath 5 on the insulating wire core 4 using an extrusion apparatus. At this time, one recess 7 is formed on the sheath outer surface 8, and the other outer surface 8 is pushed out so that another recess 7 is formed on the sheath outer surface 8 opposite to the cable diameter direction (as an example). To do). Further, the recess 7 is formed straight along the cable axis over the entire length of the cable, and the cross-sectional shape forms a square part 10 on the sheath outer surface 8 side, and continues to the square part 10 on the sheath inner surface 9 side. The triangular portion 11 is formed, and the apex 12 of the triangular portion 11 is formed so as to face the sheath inner surface 9 side. Next, as a second step, an extrusion molding device is used to extrude the stripes 6 so as to fill the respective recesses 7 at an appropriate interval immediately after the sheath 5 is extruded, so that the entire cable is formed into a circular cross section. Is done. The manufacturing of the cable 1 is completed through the above steps.

  The sheath 5 in this embodiment is foamed by blending 50 parts by weight of bis-2-ethylhexyl phthalate and 2 parts by weight of a stabilizer with respect to 100 parts by weight of the polyvinyl chloride resin. Further, the expansion ratio of the entire sheath 5 is set to 5 to 15%.

  Then, the comparison with Examples 1-3 of this invention and Comparative Examples 1-3 is demonstrated.

  First, Examples 1-3 of the present invention will be described based on Table 1.

  Example 1 of Table 1 is a case where the minimum thickness of the sheath portion is 0.2 mm. The tear load in Example 1 is 1.0 N when the sheath foaming rate is 5%, 0.9 N when the sheath foaming rate is 10%, and 0.9 N when the sheath foaming rate is 15%.

  Example 2 of Table 1 is a case where the sheath portion minimum thickness is 0.3 mm. The tear load in Example 2 is 2.1 N when the sheath foaming rate is 5%, 2.0 N when the sheath foaming rate is 10%, and 1.9 N when the sheath foaming rate is 15%.

  Example 3 is a case where the sheath portion minimum thickness is 0.4 mm. The tear load in Example 3 is 3.8 N when the sheath foaming rate is 5%, 3.6 N when the sheath foaming rate is 10%, and 3.4 N when the sheath foaming rate is 15%.

  Next, Comparative Examples 1 to 3 will be described based on Table 2.

  In Comparative Example 1 in Table 2, the sheath portion minimum thickness is 0.1 mm. The tear load in Comparative Example 1 is 0.3 N when the sheath is not foamed. Further, in the state where the sheath foaming rate is 5%, 10%, and 15%, all are 0.2N.

  In Comparative Example 2 in Table 2, the sheath portion minimum thickness is 0.5 mm. The tear load in Comparative Example 2 is 6.3 N when the sheath is not foamed. Further, 5.9N is obtained when the sheath foaming rate is 5%, 5.6N when the sheath foaming rate is 10%, and 5.3N when the sheath foaming rate is 15%.

  In Comparative Example 3 in Table 2, the sheath portion minimum thickness is 0.6 mm. The tear load in Comparative Example 3 is 9.0 N when the sheath is not foamed. On the other hand, when the sheath foaming rate is 5%, it is 8.6N, when the sheath foaming rate is 10%, it is 8.1N, and when the sheath foaming rate is 15%, it is 7.7%.

  When Examples 1 to 3 in Table 1 are compared with Comparative Example 1 in Table 2, the tear load of Comparative Example 1 is smaller than the tear load of Examples 1 to 3. However, since the minimum thickness of the sheath part of Comparative Example 1 is 0.1 mm, it can be said that it is inferior to Examples 1 to 3 in terms of the durability of the sheath.

  Comparing Examples 1 to 3 in Table 1 with Comparative Examples 2 and 3 in Table 2, Comparative Examples 2 and 3 having a sheath portion minimum thickness of 0.5 mm or more are numerical values of tear loads in Examples 1 to 3. It can be seen that the figure is overwhelmingly higher than that of.

  From the above, by forming the sheath 5 in the range where the sheath portion minimum thickness in the first to third embodiments of the present invention is 0.2 to 0.4 mm, compared with the first to third comparative examples, a certain durability is obtained. It can be seen that the figure shows that the sheath 5 can be torn by a relatively small tear load while maintaining.

  In addition, in Examples 1 to 3 of the present invention, the sheath 5 is foamed, so that innumerable hollow portions are generated inside the sheath 5. This reduces the cross-sectional area of the sheath 5 and improves tearability. In addition, since the area of the sheath 5 that is in close contact with the stripe 6 is reduced, the stripe 6 is easily peeled off from the sheath 5.

  Next, an example of the stripping work of the cable 1 will be described based on the above-described configurations and structures.

  First, an appropriate depth of cut is made with a tool such as an electric knife (not shown) at the boundary between one end of the stripe 6 at the end of the cable 1 and the sheath 5. Next, one end of the stripe 6 is grasped by hand and pulled toward the other end of the stripe 6 to peel off the stripe 6 from the sheath 5. When the stripe 6 is peeled off to a desired position in the cable axial direction, the recess 7 is expanded to concentrate the tearing load on the sheath portion minimum thickness portion, where the sheath 5 is torn and the sheath 5 can be peeled off. . Thus, the stripping operation of the cable 1 is completed.

  As described above with reference to FIGS. 1 to 3, according to the cable 1 of the present invention, it is easy to extrude the sheath 5 while maintaining good peeling workability of the sheath 5. Can be. Moreover, according to this invention, the shape of the sheath 5 can be formed easily. Further, according to the present invention, the peelability of the sheath 5 becomes better.

  Hereinafter, another embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view showing another embodiment of the cable 1 ′ of the present invention. In addition, the same code | symbol is attached | subjected to the same component as one above-mentioned embodiment, and detailed description is abbreviate | omitted.

  In FIG. 4, the cable 1 ′ is different from the cable 1 in the number and arrangement of the insulated cores 4 in the cable 1 ′ as compared with the above-described embodiment. Therefore, in this embodiment, only the number and arrangement of the insulated wire cores 4 will be described.

  The insulated wire core 4 includes a conductor 2 and an insulator 3 that covers the conductor 2. The cable 1 ′ is formed by covering three insulated wire cores 4 a, 4 b, 4 c with a sheath 5 (which is an example).

  As described above, in FIGS. 1 to 4, according to the cables 1 and 1 ′ of the present invention, it is possible to facilitate the extrusion molding of the sheath 5 while maintaining good peeling workability of the sheath 5. . Moreover, according to this invention, the shape of the sheath 5 can be formed easily. Further, according to the present invention, the peelability of the sheath 5 becomes better.

  In addition, the present invention can of course be modified in various ways within the scope not changing the gist of the present invention.

DESCRIPTION OF SYMBOLS 1,1 '... Cable 2 ... Conductor 3 ... Insulator 4, 4a, 4b, 4c ... Insulation wire core 5 ... Sheath 6 ... Stripe 7 ... Recess 8 ... Sheath outer surface 9 ... Sheath inner surface 10, 10' ... Square part 11, 11 '... triangle part 12 ... vertex

Claims (3)

In a cable in which one or a plurality of insulated wire cores including a conductor and an insulator covering the conductor are covered with a sheath, and the sheath is provided with a stripe extending straight along the cable axis.
The sheath is extruded from a foamable resin composition, and forms a recess for embedding the stripe,
The stripe is extruded from a resin composition having no foaming property, and is provided so as to be peelable from the sheath,
The concave portion of the sheath has a cross-sectional shape forming a quadrangular portion on the outer surface side of the sheath, forming a triangular portion on the inner surface side of the sheath continuously to the quadrangular portion, and the apex of the triangular portion being on the inner surface side of the sheath A cable characterized by being formed to face. The cable according to claim 1,
The overall thickness of the sheath t, t ₁ the height of the triangular portion of the recess formed in the _sheath, when the angle of the apex of the triangular portions was theta,
t / 4 ≦ t ₁ ≦ 3t, π / 4 ≦ θ ≦ π / 2
A cable characterized by The cable according to claim 1 or 2,
A cable having a thickness from the apex of the triangular portion formed in the concave portion of the sheath to the inner surface of the sheath is 0.2 to 0.4 mm.

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