JP2010129200A - Electric cable, electric cable with resin molding, and method for manufacturing the same - Google Patents

Abstract

[PROBLEMS] To effectively close the cable inlet of the upper and lower molds when the resin molding is directly injection-molded on the outer jacket of the electric cable, even if there is some variation in the outer jacket outer diameter. Provided are an electric cable that does not cause biting of the object and resin leakage, an electric cable with a resin molded body, and a method for manufacturing the same.
A conductor, an insulating core, a shield core, or a combination core thereof is covered with two or more resin insulators 16 and an outermost insulating layer is formed on a foamed layer 15 by injection molding into a resin. The compacts 18 and 19 are integrated. Further, when the resin molded body is formed by injection molding with the upper mold and the lower mold on the electric cable, the foamed layer 15 of the electric cable is compressed in the vertical direction and is not subjected to compression in the horizontal direction. To mold.
[Selection] Figure 3

Description

  The present invention relates to an electric cable in which a resin molded body is formed integrally with an intermediate portion or a terminal portion of an electric cable.

Electrical cables used for electronic equipment, automobile wiring, power cords, and the like have connectors, sensors, and the like for electrical connection at their terminal portions. Connectors and sensors are usually protected by a cover or a housing, and these covers and housing may be integrally injection-molded as a resin molded body in advance on a cable jacket portion of an electric cable terminal (for example, Patent Document 1). , 2).
Japanese Patent Laid-Open No. 10-12346 Japanese Patent Laid-Open No. 9-45399

  When integrally forming a resin molded body such as a cover or a housing as in Patent Documents 1 and 2 on an electric cable, normally, as shown in FIG. 5B, an upper mold 4a divided into two parts A lower mold 4b is used. On the other hand, the electric cable 1 is formed, for example, by covering the outer periphery of the conductor core 2 with a jacket 3 made of a resin having a withstand voltage and flame resistance. Note that the cable jacket 3 also serves as protection of the electric cable and may be formed in multiple layers. The upper mold 4a and the lower mold 4b have a semicircular fitting port 5 into which the electric cable 1 is fitted and introduced into at least one wall portion, and a resin casting cavity 6 therein. .

  If the cable jacket 3 of the electric cable 1 varies to the side with a large manufacturing tolerance, a part of the cable jacket 3 is bitten by the joint surface portion 7 of the upper and lower molds 4a and 4b, and the ear-shaped portion 3a. Become. As a result, the cable jacket is damaged, and a gap is formed in the joint surface portion 7 of the upper and lower molds 4a and 4b. Therefore, the resin protrudes during injection molding, and a burr is generated in the resin molded body. In addition, if the manufacturing tolerance varies to the side where the tolerance is small, a gap is formed between the fitting port 5 and the cable jacket 3, and the resin may leak out from the gap during injection molding. Further, in addition to the variation in the outer diameter of the outer jacket of the cable, there is also a manufacturing variation on the injection mold side, which may cause a molding failure in the resin molded body.

  The present invention has been made in view of the above-described circumstances, and when the resin molded body is directly injection-molded on the outer sheath of the electric cable, the upper and lower molds can be used even if there is some variation in the outer sheath diameter of the cable. It is an object of the present invention to provide an electric cable, an electric cable with a resin molded body, and a method for manufacturing the same, which effectively close the cable fitting opening and prevent the cable jacket from being bitten and causing resin leakage.

The electric cable according to the present invention is characterized in that a conductor, an insulating core, a shield core, or a combination core thereof is covered with two or more resin insulators, and the outermost insulating layer is formed of a foam layer. The thickness of the foam layer is preferably not less than the tolerance of the cable jacket and not more than 0.2 mm.
In the electric cable with a resin molded body according to the present invention, the resin molded body is integrated with the electric cable by injection molding, or a plurality of electric cables are bundled by the resin molded body.
Further, the method for producing an electric cable with a resin molded body according to the present invention is such that when the resin molded body is formed by injection molding with the upper mold and the lower mold on the electric cable, the foam layer of the electric cable is vertically aligned. Molded so that it is compressed and not subjected to compression in the lateral direction.

  According to the present invention, even when the outermost foam layer is compressed at the fitting opening portion of the mold, the foam layer is not crushed and protrudes into the joint portion of the upper and lower molds. In addition, by forming the fitting port of the upper and lower molds with a size that compresses the foam layer, no gap is generated between the electric cable and the fitting port, and the resin does not leak during injection molding. Thereby, the defect incidence rate of the resin molding integrally molded with the electric cable can be reduced.

  Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an example of the configuration of an electric cable according to the present invention. FIG. 1 (A) is a single-core electric cable, FIG. 1 (B) is a coaxial electric cable, and FIG. 2 (A) is a two-core electric cable. FIG. 2B shows an example of another electric cable of a single core. In the figure, 10a, 10b, 10c and 10d are electrical cables, 11 is a conductor, 12 is an insulator, 13 is a shield conductor, 14 is an inner layer insulator, 15 is a foam layer, and 16 is a resin insulator.

  The electric cable according to the present invention can be configured, for example, as a single-core cable having a shape as shown in FIG. This single-core electric cable 10a is an example in which the conductor 11 is a core and the outer periphery is covered with a resin insulator 16 with a cable jacket. The conductor 11 is a single wire or a stranded wire made of a tinned annealed copper wire or a copper alloy wire.

  The resin insulator 16 is formed of two or more layers, and the outermost layer is formed of a porous foam layer 15 with respect to the inner inner layer insulator 14. The foam layer 15 is formed, for example, by adding a foaming agent to polyethylene, polyvinyl chloride resin, or the like and physically and chemically foaming it. The inner layer insulator 14 is a non-foamed resin layer and is made of a fluororesin, a polyethylene resin, a polyvinyl chloride resin, an ethylene vinyl acetate copolymer resin, an ethylene / ethyl acrylate resin, or the like. A resin insulation material is used.

  FIG. 1B shows an example in which the electric cable according to the present invention is configured as a coaxial cable. The coaxial electric cable 10b has a configuration in which a shield conductor 13 is arranged on an insulated electric wire having a shape in which the outside of the conductor 11 is covered with an insulator 12, and is a shield core. The shield core is formed by winding a tinned annealed copper wire around the outer periphery of the insulator 12 with a horizontal winding or a braided structure. The outside of the shield core is covered with a resin insulator 16 similar to that described with reference to FIG. The resin insulator 16 is formed of two or more layers, and the outermost layer is formed of a porous foam layer 15 with respect to the inner inner layer insulator 14.

  FIG. 2A is an example in which the electric cable according to the present invention is configured as a two-core cable. This two-core electric cable 10c is a core formed by twisting a pair of insulated wires having a shape in which the outside of the conductor 11 is covered with an insulator 12, and the insulation core has a multi-core structure. It is an example of a case. The outside of the insulator 12 of the insulated wire paired is covered with the resin insulator 16 as described with reference to FIG. In this case, the resin insulator 16 is also formed of two or more layers, and the outermost layer is formed of the porous foam layer 15 with respect to the inner inner layer insulator 14.

FIG. 2B shows an example of a single-core insulated core in which a single-core insulated wire in which the outside of the conductor 11 is covered with an insulator 12 is used as a core. The electric cable 10 d further covers the outside of the insulator 12 with a resin insulator 16. In this case, the resin insulator 16 is also formed of two or more layers, and the outermost layer is formed of the porous foam layer 15 with respect to the inner inner layer insulator 14.
The configuration of the electric cable of the present invention when a multilayer resin insulator is provided as a cable jacket also for configurations other than FIGS. 1 and 2, for example, multi-core cables, multi-core coaxial cables, multi-pair cables, etc. Can be applied.

  FIG. 3 is a diagram showing a configuration example of an electric cable with a resin molded body according to the present invention. FIG. 3A shows an example in which a sensor component is formed on a cable terminal, and FIG. 3B shows an example in which a connecting member that integrates a plurality of electric cables is formed. In the figure, 17 is a sensor element, 18 is a sensor housing, and 19 is a connecting member. Description of other reference numerals is omitted by using the same reference numerals as those used in FIG.

  FIG. 3A is a schematic diagram of a wheel speed sensor cable (ABS sensor cable) used in, for example, an antilock brake system (ABS). This cable is usually an electric cable in which a pair of insulated wires is twisted into a pair and a resin insulator as a cable jacket is coated on the outside thereof. In the present invention, the ABS sensor cable can be formed using the two-core electric cable described with reference to FIG. That is, an electric cable 10c is used in which a conventional cable jacket is formed of a multilayer resin insulator 16 composed of an inner layer insulator 14 and an outermost foam layer 15.

  The sensor element 17 of the wheel speed sensor is electrically connected to a pair of insulated wires at one end of the two-core electric cable 10c as in the conventional case. The sensor housing 18 that protects the sensor element 17 is molded by injection molding using a separable upper and lower mold on the resin insulator 16 of the electric cable 10c. As will be described later, the sensor housing 18 to be molded can be excellent in appearance without molding defects or burrs.

  FIG. 3B shows a schematic diagram in which a plurality of insulated wires are assembled into a multi-core electric cable. This electric cable is an example in which the number of cores is increased by using the coaxial electric cable 10b described with reference to FIG. That is, a coaxial electric cable 10b formed by a multilayer resin insulator 16 including an inner layer insulator 14 and an outermost foam layer 15 is used as an assembled electric cable. Then, a plurality of electric cables 10b are arranged in parallel, and a connecting member 19 for connecting the cables to each other is formed by injection molding at a predetermined position using upper and lower molds. The molded connecting member 19 can be made excellent in appearance without molding defects or burrs, as in the case of the sensor housing.

  FIG. 4 is a diagram for explaining a method of manufacturing an electric cable with a resin molded body as shown in FIG. 4A is a diagram showing an outline of the upper and lower molds, FIG. 4B is a diagram showing an example of an electric cable according to the present invention, and FIG. 4C is a diagram for explaining a molding state by the upper and lower molds. is there. In the figure, 10 is an electric cable, 11 'is a conductor, 14' is an inner layer insulator, 15 'is a foam layer, 20a is an upper mold, 20b is a lower mold, 21a and 21b are fitting ports, 22 is a cavity, and 23 is A joint surface part is shown.

  As the mold for molding the resin molded body, an upper mold 20a and a lower mold 20b as shown in FIG. 4A are used. The upper and lower molds 20a and 20b have cavities 22 into which casting resin is injected, and are provided with semi-columnar fitting ports 21a and 21b into which the electric cable 10 is fitted and introduced into at least one side wall. ing. The electric cable 10 is inserted into the fitting ports 21a and 21b of the upper and lower molds 20a and 20b, and then the bonding surface portion 23 of the mold is closed. In the cavity 22 of the upper and lower molds, an injection resin injected from a resin injection port (not shown) covers the outer periphery of the electric cable 10 and is integrally molded as a resin molded body.

  In the electric cable 10 to which the resin molded body is added, as shown in a simplified manner in FIG. 4B, the outer periphery of the conductor 11 'is a non-foamed inner layer insulator 14' made of a resin having a withstand voltage and flame resistance. And the outer periphery thereof is covered with a foam layer 15 ′. The inner layer insulator 14 ′ has all the functions of insulating coating and protection as an electric cable, and may be formed in multiple layers. When the inner layer insulator 14 ′ is formed of multiple layers, the outer layer side may be non-foamed and the inner layer side may be a foamed insulator for ensuring electrical characteristics. In addition, the electric cable 10 can have various configurations shown in FIG.

  The foam layer 15 ′ (including the foam layer 15 of FIGS. 1 to 3) may be formed of a resin material different from the inner layer insulator 14 ′ (including the inner layer insulator 14 of FIGS. 1 to 3), and the same resin. It may be made of a material. The foamed layer 15 ′ is made of a crosslinked or non-crosslinked thermoplastic resin, and is formed by, for example, chemically foaming by adding a foaming agent. For example, it is made of foamed polyethylene (FPE).

  Further, the foam layer 15 ′ collapses the volume when heated and compressed with a mold, and the volume shrinks. The degree of foaming that expects volume shrinkage is 40% or less (preferably about 5 to 20%). It is preferable to do this. When the foaming degree exceeds 40%, the cable surface is rough and noticeable, and the commercial value of the cable is lowered. Further, the outer diameter D of the foam layer 15 ′ is set to be on the maximum side of the outer diameter tolerance of the electric cable, and the coating thickness d is at least within the tolerance range (for example, a single-core cable having a cable outer diameter of 7 mm). , 0.2 mm or less).

  When the resin molded body shown in FIG. 3 is molded, the electric cable 10 is set so that the electric cable 10 is held by the fitting ports 21a and 21b of the upper and lower molds 20a and 20b, as shown in FIG. 4C. The In this case, for example, the vertical diameter D1 of the fitting ports 21a and 21b when the space between the joint surfaces 23 of the upper and lower molds 20a and 20b is completely closed is smaller than the outer diameter D of the electric cable 10. It is preferable to keep it. Thereby, when the electric cable 10 is set in the upper and lower molds 20a and 20b, the foamed layer 15 'is compressed in the vertical direction at least by the fitting ports 21a and 21b.

  Further, the diameter D2 of the fitting ports 21a and 21b in the lateral direction (the direction parallel to the joint surface portion 23) is formed with a diameter (may be slightly larger) that is substantially equal to the outer diameter D of the electric cable 10, and the foam layer 15 ′ is formed. It is possible to prevent compression in the lateral direction of the mold. That is, the cable fitting ports 21a and 21b of the upper and lower molds 20a and 20b have an elliptical shape that satisfies “D1 <D2”.

  By forming the upper and lower molds 20a and 20b as described above, when the electric cable is gripped by the fitting ports 21a and 21b, the vertical foam layer 15 'is compressed, and the compressed volume is set in the lateral direction. By extruding, it is possible to prevent a gap from being generated between the foamed layer 15 ′ of the cable and the fitting openings 21 a and 21 b of the mold. As a result, the molded resin cast into the cavity 22 does not leak out, and an electric cable having a resin molded body excellent in appearance without burrs or the like can be obtained.

It is a figure which shows the structural example of the electric cable by this invention. It is a figure which shows the other structural example of the electric cable by this invention. It is a figure which shows the structural example of the electric cable with a resin molding by this invention. It is a figure explaining the outline of the manufacturing method of the electric cable with a resin molding by this invention. It is a figure explaining a prior art.

Explanation of symbols

10a, 10b, 10c, 10d ... electric cable, 11, 11 '... conductor, 12 ... insulator, 13 ... shield conductor, 14, 14' ... inner layer insulator, 15, 15 '... foam layer, 16 ... resin insulator , 20a ... upper die, 20b ... lower die, 21a, 21b ... fitting port, 22 ... cavity, 23 ... joint surface part.

Claims (5)

  An electric cable, wherein a conductor, an insulating core, a shield core, or a combination core thereof is coated with two or more resin insulators, and an outermost insulating layer is formed of a foam layer.   The electric cable according to claim 1, wherein the thickness of the foamed layer is not less than a tolerance of the cable outer diameter and not more than 0.2 mm.   An electric cable with a resin molding, wherein the electric cable according to claim 1 or 2 is integrated with a resin molding by injection molding.   The electrical cable with a resin molded body according to claim 3, wherein a plurality of electrical cables are bundled by the resin molded body.   When the resin molded body is molded into the injection molding by the upper mold and the lower mold in the electrical cable according to claim 1 or 2, the foam layer of the electrical cable is compressed in the vertical direction and compressed in the lateral direction. A method for producing an electric cable with a resin molded body, characterized in that the electric cable is molded so as not to be received.

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