Method for manufacturing electric wire harness and method for manufacturing electric wire assembly

Abstract

Provided is a method for manufacturing an electric wire harness, the electric wire harness being formed by joining a plurality of electric wires (10) equipped with terminals to each other, the electric wires (10) equipped with terminals being formed by connecting a terminal fitting (30) to one end of an electric wire (20) having a conductor (21) covered by an insulating coating (22), the method comprising: heating the insulating coating (22) in the plurality of electric wires (10) equipped with terminals to expand the insulating coating (22); and ultrasonically joining the plurality of conductors (21) to each other by applying ultrasonic vibration to the plurality of conductors (21) exposed from the plurality of electric wires (10) equipped with terminals in a state where the insulating coating (22) is expanded.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electric wire harness and a method for manufacturing an electric wire assembly. Background Art

[0002] Generally, as a method of connecting a plurality of electric wires without using a connection member such as a connector, a method has been proposed in which a plurality of conductors exposed from the ends of the plurality of electric wires are directly joined to form a conductor joint portion. Specifically, a plurality of conductors are set together in a joining machine for joining conductors, and the conductors are joined by subjecting the plurality of conductors to an ultrasonic joining process.

[0003] When an electric wire equipped with a terminal having a terminal fitting crimped on one end is used as an electric wire, if ultrasonic vibration is applied to the electric wire equipped with the terminal, the vibration is transmitted to the terminal fitting through the conductor. Therefore, there is a risk of breakage at parts with relatively low strength, such as the bent part of the terminal fitting. Therefore, patent document JP 2020-177863A proposes a technology for suppressing the breakage of terminal fittings by reducing the transmission of vibration to terminal fittings. Specifically, patent document JP 2020-177863A discloses a method for manufacturing an electric wire equipped with a terminal, in which the terminal fitting is connected to one end of an electric wire having a conductor covered by a sheath, the middle portion of the electric wire is sandwiched between a pair of plate bodies, and ultrasonic vibration is applied to the conductor exposed at the other end of the electric wire to perform ultrasonic bonding treatment on it. Summary of the invention

[0004] Patent document JP 2020-177863A discloses suppressing the transmission of vibration to terminal fittings by clamping each wire between a pair of clamps (plates). However, in order to suppress the transmission of vibration, it is necessary to apply sufficient pressure to each wire with a clamp, and for this purpose, it is desirable to use a clamp suitable for each wire. Therefore, a method is needed that can suppress the transmission of ultrasonic vibration to terminal fittings in a simpler way.

[0005] The present invention has been made in view of the problems of the prior art. An object of the present invention is to provide a method of manufacturing a wire harness and a method of manufacturing a wire assembly, which can suppress the transmission of ultrasonic vibration to a terminal fitting in a simpler manner.

[0006] A method for manufacturing an electric wire harness according to the present invention is a method for manufacturing an electric wire harness, which is formed by joining a plurality of electric wires equipped with terminals to each other, wherein the electric wires equipped with terminals are formed by connecting terminal accessories to one end of an electric wire having a conductor covered by an insulating coating, the method comprising: heating the insulating coating in the plurality of electric wires equipped with terminals to expand the insulating coating; and ultrasonically joining the plurality of conductors to each other by applying ultrasonic vibration to a plurality of conductors exposed from the plurality of electric wires equipped with terminals in a state where the insulating coating is expanded.

[0007] A method for manufacturing an electric wire assembly according to the present invention is a method for manufacturing an electric wire assembly, which is formed by joining a conductive component to an electric wire equipped with a terminal, wherein the electric wire equipped with a terminal is formed by connecting a terminal accessory to one end of the electric wire having a conductor covered by an insulating coating, the method comprising: heating the insulating coating in the electric wire equipped with the terminal to expand the insulating coating; and ultrasonically joining the conductor to the conductive component by applying ultrasonic vibration to the conductor exposed from the electric wire equipped with the terminal in a state where the insulating coating is expanded.

[0008] According to the above configuration, it is possible to provide a method of manufacturing a harness of electric wires and a method of manufacturing a wire assembly which can suppress the transmission of ultrasonic vibration to the terminal fitting in a simpler manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A : is a perspective view schematically showing an example of terminal-equipped electric wires used in the method of manufacturing the electric wire harness according to the present embodiment.

[0010] Figure 1B is a schematic diagram showing a cross section of a terminal fitting in a terminal-equipped electric wire.

[0011] Figure 2 1 is a schematic diagram showing a state in which a plurality of terminal-equipped electric wires are mounted in an ultrasonic splicer in the method of manufacturing a harness of electric wires according to the present embodiment.

[0012] Figure 3 : is a schematic diagram showing a state in which a plurality of terminal-equipped electric wires are heated in the method of manufacturing the electric wire harness according to the present embodiment.

[0013] Figure 4 1 is a schematic diagram showing a state in which a plurality of terminal-equipped electric wires are ultrasonically joined while being heated in the method of manufacturing the electric wire harness according to the present embodiment.

[0014] Figure 5 : is a schematic diagram showing another example of a state in which a plurality of terminal-equipped electric wires are heated in the method of manufacturing the electric wire harness according to the present embodiment.

[0015] Figure 6 : is a schematic diagram showing another example of a state in which a plurality of terminal-equipped electric wires are heated in the method of manufacturing the electric wire harness according to the present embodiment.

[0016] Figure 7 : is a schematic diagram showing a state in which a terminal-equipped electric wire is heated in the method of manufacturing an electric wire assembly according to the present embodiment. DETAILED DESCRIPTION

[0017] The method of manufacturing a wire harness and the method of manufacturing a wire assembly according to the present embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

[0018] [Method of manufacturing electric wire harness]

[0019] The method of manufacturing an electric wire harness of the present embodiment is a method of manufacturing an electric wire harness formed by directly joining conductors of a plurality of electric wires 10 equipped with terminals. Figure 1A and 1B As shown, each of the terminal-equipped electric wires 10 includes an electric wire 20 and a terminal fitting 30 connected to one end of the electric wire 20 .

[0020] The electric wire 20 is an insulated electric wire having a conductor 21 and an insulating coating 22 covering the periphery of the conductor 21. For the conductor 21, a stranded wire formed by stranding element wires made of a conductive metal material such as copper, copper alloy, aluminum, or aluminum alloy can be used. The insulating coating 22 is formed of a resin material having flexibility and electrical insulation. The insulating coating 22 at both ends of the electric wire 20 is removed, and a portion of the conductor 21 is exposed.

[0021] The terminal fitting 30 is crimped to one end of the exposed conductor 21 of the electric wire 20. The terminal fitting 30 is formed by processing a plate made of a conductive metal material such as copper, copper alloy, aluminum, or aluminum alloy. Figure 1B As shown, the terminal fitting 30 includes a wire connecting portion 31 and an electrical connecting portion 32 .

[0022] The wire connecting portion 31 of the terminal fitting 30 has a conductor crimping portion 311 crimped to the conductor 21 of the wire 20 and a covering crimping portion 312 crimped to the insulating covering 22 of the wire 20. The conductor crimping portion 311 has a pair of conductor crimping pieces 311a. By pressing the conductor crimping pieces 311a, the conductor 21 is crimped and fixed to the conductor crimping portion 311. Similarly, the covering crimping portion 312 has a pair of covering crimping pieces 312a, and the insulating covering 22 is crimped and fixed to the covering crimping portion 312 by pressing the covering crimping pieces 312a. This connects the terminal fitting 30 to the wire 20, and electrically connects the terminal fitting 31 to the conductor 21 of the wire 20.

[0023] The electrical connection part 32 of the terminal fitting 30 has a square tubular box part 33 into which a lug formed on the male terminal of the connection counterpart is inserted from the distal end side of the square tubular box part 33. A coupling part 34 is arranged on the side of the electrical connection part 32 opposite to the lug insertion side, and the wire connection part 31 and the electrical connection part 32 are integrated by the coupling part 34 therebetween.

[0024] The box portion 33 of the electric connection portion 32 includes a bottom plate 331, side plates 332 and 333 erected from both edges of the bottom plate 331, and a top plate 334 closing the upper portion of the box portion 33. A contact 335 protruding toward the inside of the box portion 33 is formed on the top plate 334. The coupling portion 34 is integrally formed on the electric wire connection portion 31 side of the bottom plate 331, and a spring contact 336 is continuously connected to the end side of the bottom plate 331. The spring contact 336 is formed in the box portion 33 by folding back from the end of the bottom plate 331 toward the electric wire connection portion 31. The spring contact 336 has a pressing contact 337 protruding toward the contact 335 on the top plate 334.

[0025] When the conductor 21 of the other end side of the electric wire 20 of which one end is connected to the terminal fitting 30 in the electric wire 10 equipped with a terminal is subjected to ultrasonic bonding treatment, ultrasonic vibration is transmitted to the terminal fitting 30 through the electric wire 20. The spring contact 336 vibrates in response to the ultrasonic vibration transmitted in the terminal fitting 30. Therefore, a large load is applied to the portion continuously connected to the bottom plate 331, and there is a risk of rupture. Therefore, in the method for manufacturing an electric wire harness according to the present embodiment, when the conductors 21 of a plurality of electric wires 10 equipped with terminals are ultrasonically bonded to each other, the transmission of the terminal fitting 30 of the ultrasonic vibration is suppressed.

[0026] In the method for manufacturing an electric wire harness according to the present embodiment, first, Figure 1A and 1B As described above, the insulating coating 22 at both ends of the electric wire 20 of the terminal-equipped electric wire 10 is removed, and a part of the conductor 21 is exposed. Then, the terminal fitting 30 is crimped to one end of the electric wire 20.

[0027] Then, if Figure 2 As shown, the conductor 21 exposed at the other end of the electric wire 20 is installed in the ultrasonic splicer 40. At this time, the conductors 21 at the other end side of the electric wire are installed in the ultrasonic splicer 40 in a state where the ends of the conductors 21 are aligned in a direction perpendicular to the length direction of the electric wire 20.

[0028] The ultrasonic bonder 40 includes a horn 41 located below the conductor 21 and an anvil 42 located above the conductor 21. In addition, the ultrasonic bonder 40 includes a fixed side plate and a movable sliding core located on the side of the conductor 21. The horn 41 ultrasonically vibrates in the horizontal direction in the figure by a vibrator. Knurling consisting of a plurality of protrusions protruding in a direction orthogonal to the vibration direction is formed on the upper surface (the surface in contact with the conductor 21) of the horn 41, which suppresses sliding between the upper surface of the horn 41 and the conductor 21. Similarly, knurling consisting of a plurality of protrusions protruding in a direction orthogonal to the vibration direction is formed on the lower surface of the anvil 42. The space defined by the horn 41, the side plate, the sliding core and the anvil 42 of the ultrasonic bonder 40 is used as a bonding processing space, and the conductors 21 installed in the bonding processing space are ultrasonically bonded to each other.

[0029] Next, while the plurality of terminal-equipped electric wires 10 are mounted in the ultrasonic splicer 40, the insulating coating 22 of the electric wire 20 among the plurality of terminal-equipped electric wires 10 is heated to expand the insulating coating 22. Specifically, as shown in FIG. Figure 3 As shown, at least a portion of each insulating coating 22 is heated using a heater 50. When each insulating coating 22 is heated, the entire heated portion 60 of each insulating coating 22 expands outward in the radial direction of each electric wire 20, and this reduces the adhesion between each conductor 21 and each insulating coating 22.

[0030] The method of heating each insulating coating 22 is not particularly limited, and it is possible to use, for example, a heater 50 that emits warm air. Specifically, in a state where the heater 50 is arranged near each terminal-equipped electric wire 10, warm air 51 is emitted from the heater 50, and the warm air 51 is blown out from the side surface of each insulating coating 22. This heats a part of each insulating coating 22 to the temperature of the warm air 51, and produces each heated portion 60. The heating medium that comes into contact with each insulating coating 22 is not limited to gas, and may be liquid.

[0031] Then, while the insulating coating 22 is heated, ultrasonic vibration is applied to the plurality of conductors 21 installed in the ultrasonic bonder 40, so that the conductors 21 are ultrasonically bonded to each other. Figure 4 As shown, after a plurality of conductors 21 are sandwiched between a horn 41 and an anvil 42 of an ultrasonic bonder 40, current is passed through a vibrator. As a result, the horn 41 is ultrasonically vibrated by the vibrator, and ultrasonic vibration energy is transmitted to the conductors 21. After oxide films and the like on the surfaces of the respective conductors 21 are destroyed and removed, the conductors 21 are bonded to each other.

[0032] Finally, the joined conductors 21 are taken out from the ultrasonic joiner 40 , the respective insulating covers 22 are cooled to room temperature, and thus an electric wire bundle formed by ultrasonically joining the conductors 21 of a plurality of terminal-equipped electric wires 10 can be obtained.

[0033] If each insulating coating 22 is not heated, each conductor 21 and each insulating coating 22 adhere to each other, and therefore the adhesion between each conductor 21 and each insulating coating 22 is high. If the adhesion between each conductor 21 and each insulating coating 22 is high, the friction between each conductor 21 and each insulating coating 22 is also high. Therefore, if ultrasonic vibration is applied to each conductor 21 exposed at the other end of each electric wire 20, each conductor 21 and each insulating coating 22 will vibrate as a whole. That is, each conductor 21 and each insulating coating 22 vibrate at approximately the same frequency. As a result, the ultrasonic vibration is transmitted to each terminal fitting 30 through each conductor 21 and each insulating coating 22, and therefore there is a risk of each terminal fitting 20 being broken.

[0034] In contrast, when each insulating coating 22 is heated, the entirety of each insulating coating expands radially outward at each heated portion 60 thereof, and thus the adhesion between each conductor 21 and each insulating coating becomes low. When the adhesion between them becomes low, the force that moves each conductor 21 due to ultrasonic vibration becomes greater than the static friction between each conductor 21 and each insulating coating 22, so each conductor 21 and each insulating coating 22 vibrate independently of each other. That is, each conductor 21 and each insulating coating 22 vibrate at different frequencies. If each conductor 21 and each insulating coating 22 vibrate independently of each other, sliding occurs between each conductor 21 and each insulating coating 22, and friction (dynamic friction) is generated between each conductor 21 and each insulating coating 22. As a result, by this friction, the ultrasonic vibration transmitted to each conductor 21 and each insulating coating 22 is attenuated, and thus the ultrasonic vibration is difficult to be transmitted to each terminal fitting 30, and the rupture of each terminal fitting 20 can be suppressed.

[0035] Therefore, it is preferable that when each insulating coating 22 is heated, the temperature of each insulating coating 22 is equal to or higher than the temperature at which each insulating coating 22 expands and each conductor 21 and each insulating coating 26 start to move independently of each other. That is, it is preferable that when each insulating coating 22 is heated, the temperature of each insulating coating 22 is equal to or higher than the temperature at which each insulating coating 22 expands and each conductor 21 and each insulating coating 22 vibrate at frequencies different from each other.

[0036] Incidentally, although there is no particular limitation on the upper limit of the temperature of each insulating coating 22 when heating each insulating coating 22, the upper limit may be the upper limit of the temperature determined when processing each electric wire 20, ie, for example, the heat-resistant temperature.

[0037] As described above, in the manufacturing method of the present embodiment, the insulating coating 22 can be heated in a state where the plurality of terminal-equipped electric wires 10 are installed in the ultrasonic splicer 40. However, the timing of heating the insulating coating 22 is not limited to this mode. For example, the plurality of terminal-equipped electric wires 10 may be installed in the ultrasonic splicer 40 after the insulating coating 22 of the terminal-equipped electric wires 10 is preheated.

[0038] like Figure 3 As shown, when each insulating coating 22 is heated, each heated portion 60 can be at least a portion of each insulating coating 22. For example, each heated portion 60 can be located near a middle position of each insulating coating 22, which is located between each terminal fitting 30 and each conductor 21 exposed at the other end of each electric wire 20. In addition, each heated portion 60 of each insulating coating 22 can be located near each terminal fitting 30, or near each conductor 21 exposed at the other end of each electric wire 20.

[0039] In addition, if Figure 5 As shown, each heated portion 60 may be the entirety of each terminal fitting 30 and each insulating coating 22 in each terminal-equipped electric wire 10. In particular, since the entirety of each insulating coating 22 is each heated portion 60, each conductor 21 and each insulating coating 22 easily vibrate independently of each other, and thus sliding occurs between each conductor 21 and each insulating coating 22, and ultrasonic vibration is easily attenuated.

[0040] like Figure 3 As shown, the number of heated portions 60 of each insulating coating 22 may be one. Figure 6 As shown, the number of heated portions 60 may be more than one along the length direction of each electric wire 20. If the number of heated portions 60 is one, each insulating coating 22 can be easily heated. If the number of heated portions 60 is more than one, the number of portions where sliding occurs between each conductor 21 and each insulating coating 22 increases, so that ultrasonic vibration is easily attenuated.

[0041] As described above, there is no particular limitation on the method of heating each insulating cover 22, and each heated portion 60 may be produced by blowing warm air to each insulating cover 220. In addition, each heated portion 60 may be produced by spraying heated liquid onto each insulating cover 22. In addition, each heated portion 60 may be produced by heating each insulating cover 22 using a thermostatic chamber.

[0042] As long as there is no influence on the ultrasonic joint portion formed by ultrasonically joining the plurality of conductors 21 and the terminal crimping portion formed by crimping each terminal fitting 20 to one end of each electric wire 20, each heated portion 60 can be produced by immersing each electric wire 20 and each terminal fitting 30 in the heated liquid.

[0043] In addition, the thickness (diameter) of the wires 20 of the plurality of terminal-equipped wires 10 may be the same or different from each other. In the present embodiment, regardless of the thickness of each wire 20, each heated portion 60 can be generated in each wire 20, thereby attenuating the ultrasonic vibration of each terminal fitting 30.

[0044] In this way, the method of manufacturing a wire bundle according to the present embodiment is a method of manufacturing a wire bundle formed by connecting a plurality of terminal-equipped wires 10 to each other, each of the terminal-equipped wires 10 being formed by connecting respective terminal fittings 30 to one end of respective wires 20 having respective conductors 21 covered by respective insulating coatings 22. Further, the manufacturing method includes a step of heating the insulating coatings 22 in the plurality of terminal-equipped wires 10 to expand the insulating coatings 22. Further, the manufacturing method includes a step of ultrasonically bonding the plurality of conductors 20 to each other by applying ultrasonic vibration to the plurality of conductors 21 exposed from the plurality of terminal-equipped wires 10 while the insulating coatings 22 are expanded.

[0045] In the manufacturing method of the present embodiment, since ultrasonic vibration is applied to the conductor 21 while the insulating coating 22 expands, sliding occurs between the conductor 21 and the insulating coating 22, and frictional force is generated between the conductor 21 and the insulating coating 22. As a result, the ultrasonic vibration transmitted to the conductor 21 and the insulating coating 22 by the frictional force is attenuated, and thus the ultrasonic vibration is difficult to be transmitted to the terminal fitting 30, and the breakage of the terminal fitting 30 can be suppressed. In addition, in the manufacturing method of the present embodiment, since it is not necessary to clamp each electric wire with a pair of clamps (plates) as disclosed in JP 2020-177863A, the transmission of ultrasonic vibration to the terminal fitting can be suppressed in a simpler manner.

[0046] In the present embodiment, when the respective insulating coatings 22 are heated, the temperature of the respective insulating coatings can be equal to the temperature at which the respective conductors and the respective insulating coatings in the respective terminal-equipped electric wires 10 vibrate at different frequencies when ultrasonic vibration is applied to the respective conductors 21 in a state where the respective insulating coatings are expanded. As a result, sliding occurs between the respective conductors 21 and the respective insulating coatings 22, and frictional force is generated therebetween. This can attenuate the ultrasonic vibrations transmitted to the respective conductors 21 and the respective insulating coatings 22.

[0047] In the present embodiment, each insulating cover 22 can be heated by bringing at least one of heated warm air and heated liquid into contact with each insulating cover 22. Therefore, each heated portion 60 can be produced with a simple device such as a warm air generator.

[0048] In the present embodiment, more than one portion of each insulating coating 22 in each terminal-equipped electric wire 10 can be heated. If the number of heated portions 60 is one, it is possible to easily heat each insulating coating 22. If the number of heated portions 60 is more than one, the number of portions where sliding occurs between each conductor 21 and each insulating coating 22 increases, so that ultrasonic vibration is easily attenuated.

[0049] In the present embodiment, the entirety of each terminal fitting and each insulating coating in each terminal-equipped electric wire 10 can be heated. As a result, it becomes easy for each conductor 21 and each insulating coating 22 to vibrate independently of each other. Therefore, sliding occurs between each conductor 21 and each insulating coating 22, and ultrasonic vibration is easily attenuated.

[0050] [Method of manufacturing electric wire assembly]

[0051] Next, the method of manufacturing the electric wire assembly according to the present embodiment will be described in detail. The description overlapping with the description of the method of manufacturing the electric wire harness described above will be omitted.

[0052] As described above, by forming the heated portion 60 in the insulating coating 22 of the terminal-equipped electric wire 10, the transmission of ultrasonic vibration to the terminal fitting can be suppressed. This attenuation method can be applied not only to the manufacture of electric wire bundles but also to the manufacture of electric wire assemblies formed by ultrasonically joining the terminal-equipped electric wire and the conductive member.

[0053] In the method for manufacturing a wire assembly according to the present embodiment, first, a wire 10 equipped with a terminal is produced. The number of wires 10 equipped with a terminal may be one or more. In addition, a conductive component 70 to be connected to the wire 10 equipped with a terminal is produced. There is no particular limitation on the conductive component 70, and an example of the conductive component 70 is a metal terminal or a bus bar other than the terminal fitting 30.

[0054] Then, if Figure 7 As shown, the conductor 21 and the conductive member 70 exposed at the other end of the electric wire 20 are installed in the ultrasonic bonder 40. At this time, the conductor 21 and the conductive member 70 of the electric wire 20 are installed in the ultrasonic bonder 40 so that they overlap each other in a direction perpendicular to the length direction of the electric wire 20.

[0055] Next, while the terminal-equipped electric wire 10 and the conductive member 70 are mounted in the ultrasonic splicer 40 , the insulating coating 22 is expanded by heating the insulating coating 22 of the electric wire 20 in the terminal-equipped electric wire 10 to produce the heated portion 60 .

[0056] Then, the conductor 21 and the conductive member 70 are ultrasonically bonded by applying ultrasonic vibration to the conductor 21 and the conductive member 70 installed in the ultrasonic bonder 40 while heating the insulating cover 22 .

[0057] Finally, the joined conductor 21 and conductive member 70 are taken out of the ultrasonic bonder 40, and the insulating coating 22 is cooled to room temperature. Thus, a wire assembly formed by ultrasonically bonding the conductor 21 and conductive member 70 in the terminal-equipped wire 10 can be obtained.

[0058] Thus, the method for manufacturing a wire assembly according to the present embodiment is a method for manufacturing a wire assembly formed by joining a conductive component 70 to a terminal-equipped wire 10, the terminal-equipped wire 10 being formed by connecting a terminal fitting 30 to one end of the wire 20 having a conductor 21 covered by an insulating coating 22. The manufacturing method includes a step of heating the insulating coating 22 in the terminal-equipped wire 10 to expand the insulating coating 22. Furthermore, the manufacturing method includes a step of ultrasonically joining the conductor 21 to the conductive component 70 by applying ultrasonic vibration to the conductor 21 exposed from the terminal-equipped wire 10 while the insulating coating 22 is expanded.

[0059] In the manufacturing method of the present embodiment, since ultrasonic vibration is applied to the conductor 21 while the insulating coating 22 expands, sliding also occurs between the conductor 21 and the insulating coating 22, and frictional force is generated between the conductor 21 and the insulating coating 22. As a result, the ultrasonic vibration transmitted to the conductor 21 and the insulating coating 22 is attenuated by the frictional force. Therefore, the ultrasonic vibration is difficult to be transmitted to the terminal fitting 30, and the breakage of the terminal fitting 30 can be suppressed.

[0060] Although specific embodiments have been described, these embodiments are disclosed only by way of example and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be implemented in a variety of other forms; furthermore, various omissions, substitutions, and changes in the forms of the embodiments described herein may be made without departing from the spirit of the invention. The appended claims and their counterparts are intended to cover such forms or modifications that fall within the scope and spirit of the invention.

Claims

1. A method for manufacturing an electric wire harness formed by joining a plurality of electric wires equipped with terminals to each other, the electric wires equipped with terminals being formed by connecting a terminal fitting to one end of an electric wire having a conductor covered with an insulating coating, the method comprising: heating the insulation coatings in the plurality of terminal-equipped electric wires to expand the insulation coatings; as well as The plurality of conductors are ultrasonically bonded to each other by applying ultrasonic vibration to the plurality of conductors exposed from the plurality of terminal-equipped electric wires in a state in which the insulating coating is expanded.

2. The method for manufacturing an electric wire harness according to claim 1, wherein: The temperature of the insulating coating when the insulating coating is heated is equal to a temperature at which the conductor and the insulating coating in each terminal-equipped electric wire vibrate at different frequencies when ultrasonic vibration is applied to the conductor in a state in which the insulating coating is expanded.

3. The method for manufacturing an electric wire harness according to claim 1 or 2, wherein: The insulating coating is heated by bringing at least one of heated warm air and heated liquid into contact with the insulating coating.

4. The method for manufacturing an electric wire harness according to claim 1 or 2, wherein: One or more portions of the insulating coating in each of the terminal-equipped electric wires are heated.

5. The method for manufacturing an electric wire harness according to claim 1 or 2, wherein: The entirety of the terminal fitting and the insulating coating in each terminal-equipped electric wire is heated.

6. A method of manufacturing an electric wire assembly formed by joining a conductive member to an electric wire equipped with a terminal formed by connecting a terminal fitting to one end of an electric wire having a conductor covered with an insulating coating, the method comprising: heating the insulating coating in the terminal-equipped electric wire to expand the insulating coating; as well as The conductor is ultrasonically bonded to the conductive member by applying ultrasonic vibration to the conductor exposed from the terminal-equipped electric wire in a state in which the insulating coating is expanded.

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