Method for manufacturing composite cable

Abstract

To provide a method for manufacturing a composite cable that can suppress an increase in component count and weight.SOLUTION: Provided is a method for manufacturing a composite cable formed by joining together a plurality of covered electric wires, each of which includes a conductor covered with an insulator, the method comprising: a first step in which the plurality of covered electric wires are arranged adjacent to each other; a second step in which a pressure-applying jig is used to apply pressure in a direction such that the plurality of covered electric wires, arranged adjacent to each other in the first step, are pressed against each other; and a third step in which the plurality of covered electric wires, having been pressure-applied in the second step, are exposed to an atmosphere of supercritical carbon dioxide for at least a prescribed duration.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a composite cable. [Background technology]

[0002] Conventionally, a composite cable has been proposed in which a plurality of electric wires are twisted together and then spirally wrapped with a tape member (see Patent Document 1). Also, a heat-shrinkable tube capable of accommodating a plurality of electric wires and having an adhesive layer on its inner circumferential surface has been proposed (see Patent Document 2). Such a heat-shrinkable tube can also be used to form a composite cable. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-859 [Patent Document 2] Patent Publication No. 2021-57953 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the techniques described in Patent Documents 1 and 2 require tape members and heat-shrinkable tubes when manufacturing a composite cable, which leads to an increase in the number of parts and weight.

[0005] The present invention has been made to solve these conventional problems, and its object is to provide a method for manufacturing a composite cable that can suppress an increase in the number of parts and weight. [Means for solving the problem]

[0006] The manufacturing method of a composite cable according to the present disclosure is a manufacturing method of a composite cable in which a plurality of insulated electric wires, each having a conductor covered with an insulator, are joined together, and includes the following steps: a first step of arranging the plurality of insulated electric wires adjacent to each other; a second step of applying pressure to the plurality of insulated electric wires arranged adjacent to each other in the first step using a pressure application jig in a direction in which the plurality of insulated electric wires arranged adjacent to each other in the first step are pressed against each other; and a third step of exposing the plurality of insulated electric wires in the pressure applied state in the second step to a supercritical carbon dioxide atmosphere for a predetermined period of time or more. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a method for manufacturing a composite cable that can suppress an increase in the number of parts and weight. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a composite cable according to an embodiment of the present invention; [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] 3A to 3C are process diagrams illustrating a method for manufacturing a composite cable according to the present embodiment. [Figure 4] FIG. 4 is a schematic diagram illustrating the second step shown in FIG. 3. [Figure 5] FIG. 4 is a schematic diagram illustrating the third step shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are applied as appropriate to the details of the omitted technologies within the scope of the content described below.

[0010] Fig. 1 is a perspective view showing a composite cable according to this embodiment, and Fig. 2 is a cross-sectional view taken along line AA shown in Fig. 1. As shown in Fig. 1 and Fig. 2, the composite cable 1 according to this embodiment is formed by coupling together a plurality of coated electric wires 10, each of which has a conductor 11 coated with an insulator 12.

[0011] The conductor 11 is made of a metal such as copper or aluminum, an alloy of these metals, or a metal-plated material thereof. In the example shown in Figures 1 and 2, the conductor 11 is made of a single wire, but is not limited to a single wire and may be made of a twisted wire made of twisted metal wires or the like.

[0012] The insulator 12 covers the conductor 11. The insulator 12 is made of, for example, PP (Polypropylene), PE (Polyethylene), PVC (Polyvinyl Chloride), etc. In this embodiment, the insulator 12 is not limited to PP or the like as long as it exhibits a plasticizing effect when impregnated with carbon dioxide in a supercritical state, as will be described later, and a thermoplastic resin is preferable to a thermosetting resin such as a phenolic or epoxy resin.

[0013] 2, the composite cable 1 according to this embodiment is in a composite state in which the resins constituting the insulators 12 are self-bonded to each other at the contact portions C. That is, since the composite cable 1 is joined by the self-bonding of the insulators 12, it does not need to include a tape member or a heat-shrinkable tube.

[0014] In the example shown in Figures 1 and 2, the composite cable 1 is configured without a tape member or a heat-shrinkable tube, but this is not limited to this and the composite cable 1 may be configured with these for reinforcement purposes.

[0015] Next, a method for manufacturing the composite cable 1 according to this embodiment will be described. The composite cable 1 according to this embodiment is manufactured by exposing it to a carbon dioxide atmosphere in a supercritical state. Fig. 3 is a process chart showing the manufacturing method of the composite cable 1 according to this embodiment.

[0016] First, a first step is performed. In the first step, a plurality of insulated electric wires 10 are arranged adjacent to each other. Note that, after the plurality of insulated electric wires 10 are arranged adjacent to each other in the first step, they may be further twisted to form a twisted configuration. In addition, a connector 100 (see FIG. 4) may be connected to the plurality of insulated electric wires 10.

[0017] Next, the second step is performed. FIG. 4 is a schematic diagram showing the second step shown in FIG. 3. The multiple insulated electric wires 10 arranged adjacent to each other in the first step have connectors 100 connected to their ends. In the second step, as shown in FIG. 4, a pressure application jig 200 is set on the multiple insulated electric wires 10 in this state. The pressure application jig 200 applies pressure to the multiple insulated electric wires 10 arranged adjacent to each other so that they press against each other. The pressure application jig 200 has a spring structure and is configured to be able to compress the multiple insulated electric wires 10, but is not limited to this, and for example, a cable tie may be used. The pressure application jig 200 may also be configured with two vises or the like that compress the insulated electric wires in the up-down direction and the left-right direction, respectively.

[0018] Referring again to FIG. 3, the third step is carried out after the second step is completed. FIG. 5 is a schematic diagram showing the third step shown in FIG. 3. In the third step, a manufacturing apparatus 300 shown in FIG. 5 is used. The manufacturing apparatus 300 includes a supercritical processing chamber 310. A plurality of coated electric wires 10 with pressure application jigs 200 set thereon are housed in the supercritical processing chamber 310. The manufacturing apparatus 300 also includes piping 320, a carbon dioxide cylinder 330, and a pump P. The supercritical processing chamber 310 is connected to the carbon dioxide cylinder 330 via the piping 320. The piping 320 is also provided with a pump P, which is capable of pumping carbon dioxide at high pressure.

[0019] In this manufacturing apparatus 300, the pump P can fill the supercritical processing chamber 310 with high-pressure carbon dioxide. In particular, by using the pump P to increase the pressure of the carbon dioxide, it is also possible to increase the temperature of the carbon dioxide. Here, the carbon dioxide can be brought into a supercritical state by being at least 31.1°C and at 7.38 MPa. In the third step, the multiple coated electric wires 10 on which the pressure application jig 200 was set in the second step are exposed to a carbon dioxide atmosphere in a supercritical state. In particular, in the third step, the coated electric wires 10 are exposed to the carbon dioxide atmosphere in a supercritical state for a sufficient time (an example of a predetermined time) until the carbon dioxide impregnates the resin constituting the insulator 12 of the coated electric wires 10 and the solubility reaches a saturated state.

[0020] Here, a supercritical fluid has a density and dissolving power similar to that of a liquid, while its viscosity and diffusion coefficient are similar to that of a gas. In other words, a supercritical fluid has the diffusive power of a gas and the cohesive power of a liquid. When dissolved in a polymer, such a supercritical fluid has a plasticizing effect, such as a reduction in the glass transition point, viscosity, and surface tension. Therefore, multiple insulated electric wires 10 are impregnated with supercritical carbon dioxide, and pressure is applied between the plasticized insulators 12, causing the interfaces between the insulators 12 to bond gently and become welded. This results in the multiple insulated electric wires 10 self-bonding to each other.

[0021] An example of detailed conditions for the third step is an impregnation pressure of 10 MPa, an impregnation temperature of 40° C., and an impregnation time of 2 hours. The crimping force, which indicates the bonding strength of the coated electric wire 10 manufactured under these conditions, is 18 kPa.

[0022] Increasing the impregnation pressure, impregnation temperature, and impregnation time allows the insulator 12 to be impregnated with more carbon dioxide in a supercritical state, resulting in a plasticizing effect. Therefore, the impregnation pressure may be higher than 10 MPa, the impregnation temperature may be higher than 40°C, and the impregnation time may be longer than 2 hours. Furthermore, if the impregnation time is longer (for example, 3 hours or longer), the impregnation pressure may be 7.38 MPa, which is the pressure at which the supercritical state is reached, and the impregnation temperature may also be 31.1°C, which is the temperature at which the supercritical state is reached. Furthermore, depending on the crimping force required for the composite cable 1, the impregnation time may be shorter. Furthermore, the pressure applied by the pressure application jig 200 in the second step may also be changed depending on the required crimping force.

[0023] Referring again to Figure 3, in the fourth step, carbon dioxide is recovered from the supercritical processing chamber 310. The recovery is carried out, for example, by connecting a separate recovery container to the supercritical processing chamber 310. At this time, the carbon dioxide is recovered while the pressure inside the supercritical processing chamber 310 is reduced. The reduction rate at this time is, for example, 0.5 MPa.

[0024] In the composite cable 1 manufactured as described above, the insulators 12 are joined together with a width of, for example, several tens of micrometers. In other words, the insulated electric wires 10 are joined together on the very surface of the insulators 12, leaving no effect on the core wire. Furthermore, carbon dioxide is impregnated into the connectors and other parts of the insulated electric wires 10 to which no pressure is applied. However, this carbon dioxide is released when the composite cable 1 is exposed to air, and the plasticizing properties of the insulators 12 are lost, so there is no effect on the mechanical performance.

[0025] In this way, according to the manufacturing method of the composite cable 1 of this embodiment, multiple insulated electric wires 10 are exposed to a supercritical carbon dioxide atmosphere for a predetermined time or longer, and the supercritical carbon dioxide plasticizes the insulators 12 of the insulated electric wires 10. Here, since the multiple insulated electric wires 10 are under pressure, the interfaces between the plasticized insulators 12 gradually bond and form a fused state. As a result, the composite cable 1 is self-bonded between the insulated electric wires 10 without using tape or heat-shrink tubing, which increases the number of parts and weight. Therefore, a manufacturing method of the composite cable 1 can be provided that can suppress an increase in the number of parts and weight.

[0026] Furthermore, in this embodiment, the pressure application jig 200 is used, so that the influence of the skill of the worker is suppressed, and a composite cable 1 having a certain level of coupling performance can be obtained.

[0027] Furthermore, the carbon dioxide can be reused by the fourth step of recovering the carbon dioxide that has been brought to a supercritical state in the third step. Also, because no tape is used, the process can be easily disassembled for disposal and can be easily recycled afterwards.

[0028] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and modifications may be made within the scope of the spirit of the present invention, and if possible, publicly known or well-known technologies may be combined.

[0029] For example, in this embodiment, the manufacturing method of the composite cable 1 does not particularly limit the location where the pressure application jig 200 is set, but the location where it is set may be any location, and when it is used as a wire harness, for example, it will be set in the optimal location for each vehicle model.

[0030] Furthermore, in the manufacturing method of the composite cable 1 according to this embodiment, if possible, the setting of the pressure application jig 200 and the supercritical carbon dioxide treatment may be performed automatically.

[0031] 5 is assumed to use an industrial carbon dioxide cylinder 330, but if possible, carbon dioxide emitted from factories, thermal power plants, etc. or from the atmosphere may be captured and used. In particular, capturing and using carbon dioxide emitted from factories, thermal power plants, etc. or from the atmosphere can also contribute to suppressing an increase in carbon dioxide emissions.

[0032] 1 and 2, the insulated electric wires 10 are assumed to have the same diameter, but they are not limited to the same diameter and may have different diameters. Furthermore, the insulators 12 may also be different among the insulated electric wires 10. [Explanation of symbols]

[0033] 1: Composite cable 10: Insulated wire 11: Conductor 12: Insulator 100: Connector 200: Pressure application jig 300: Manufacturing equipment 310: Supercritical processing chamber 320: Piping 330: Carbon dioxide cylinder C: Contact part P: Pump

Claims

1. A method for manufacturing a composite cable in which a plurality of coated electric wires each having a conductor coated with an insulator are joined together, comprising the steps of: A first step of arranging a plurality of coated electric wires adjacent to each other; a second step of applying pressure to the adjacent insulated electric wires in a direction in which the adjacent insulated electric wires are pressed against each other by a pressure application tool; a third step of exposing the plurality of coated electric wires to which pressure has been applied in the second step to a carbon dioxide atmosphere in a supercritical state for a predetermined period of time or more; A method for manufacturing a composite cable comprising:

2. A fourth step of recovering the carbon dioxide brought to a supercritical state in the third step is provided.

2. The method for producing a composite cable according to claim 1.

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