Cable connection structure and manufacturing method of the cable connection structure

A cable connection structure includes a round cable, a flat cable, a holder holding an end portion of the round cable and an end portion of the flat cable and pulling out the round cable and the flat cable to overlap each other in a same direction, a connecting portion in which a core wire exposed from the end portion of the round cable and a conductor exposed from the end portion of the flat cable held by the holder are connected to each other, and a mold resin portion collectively covering the outer circumference of the holder and the outer circumference of the round cable and the flat cable pulled out from the holder.

CROSS REFERENCE TO RELATED APPLICATION

The present application is based on, and claims priority from Japanese Patent Application No. 2018-043944, filed Mar. 12, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present application relates to a cable connection structure for connecting a round cable and a flat cable and a manufacturing method of the cable connection structure.

BACKGROUND ART

A conventional cable connection structure of this kind is illustrated inFIG. 19. InFIG. 19, the conventional cable connection structure includes a holder50, a plurality of round cables W1held by the holder50, a flat cable W2held by the holder50, and a mold resin portion51covering the outer circumference of the holder50.

The plurality of round cables W1and the flat cable W2held by the holder50overlap each other at the end portions thereof, and are pulled out in mutually opposite directions. Core wires (not illustrated) at end portions of the round cables W1and conductors (not illustrated) at an end portion of the flat cable W2are connected to each other by connecting portions53formed by ultrasonic welding or the like.

The mold resin portion51collectively covers the holder50and the round cables W1and the flat cable W2pulled out from the holder50. Accordingly, the portion including the connecting portions53is waterproofed by the mold resin portion51.

The core wires (not illustrated) of the round cables W1and the conductors (not illustrated) of the flat cable W2are connected by, for example, ultrasonic welding using an ultrasonic welding device30, as illustrated inFIG. 20. The ultrasonic welding device30includes an anvil34that places the holder50in a positioned state, and a horn33that applies, while applying pressure, ultrasonic vibration (in the direction of the arrow inFIG. 10) to the position in which the core wires (not illustrated) of the round cables W1and the conductors (not illustrated) of the flat cable W2overlap each other. The horn33is provided at the distal end of an arm portion32whose base end portion is supported by a device main body31.

Incidentally, when the holder50holding the round cables W1and the flat cable W2is set in the ultrasonic welding device30, the round cables W1may have to be set away from the ultrasonic welding device30, and the flat cable W2may have to be set in the space between the horn33and the device main body31in some cases. For example, in a case where the round cables W1compose a long wire harness (not illustrated), the wire harness (not illustrated) may not be set in the space between the horn33and the device main body31.

SUMMARY

Although the flat cable W2is excellent in flexibility in the direction of bending the flat surface, it can hardly be bent in the direction orthogonal to the flat surface (lateral direction). Therefore, there is a problem that it is difficult to perform ultrasonic welding in a case where the flat cable W2is sufficiently longer than the distance between the horn33and the device main body31. There is a similar problem with a connecting device other than the ultrasonic welding device30.

The present application has been conceived to solve the problem described above, and an object of the present application is to provide a cable connection structure, as well as a manufacturing method of the cable connection structure, capable of being manufactured using a connecting device such as an ultrasonic welding device regardless of a length of a flat cable.

A cable connection structure according to a first aspect of the present application includes: a round cable having a round cross section and including a core wire and a round insulating sheath covering the outer circumference of the core wire; a flat cable having a cross section in a flat rectangular shape and including a tabular conductor and a flat insulating sheath covering the conductor; a holder holding the end portion of the round cable and the end portion of the flat cable and pulling out the round cable and the flat cable in the same direction in an overlapped state; a connecting portion in which the core wire exposed from an end portion of the round cable and the conductor exposed from an end portion of the flat cable held by the holder are connected to each other; and a waterproof exterior portion collectively covering the outer circumference of the holder and the outer circumference of the round cable and the flat cable pulled out from the holder.

A manufacturing method of a cable connection structure according to a second aspect of the present application includes: a cable setting step of holding, in a state in which a round cable and a flat cable are pulled out in a same direction in an overlapped state, the end portion of the round cable and the end portion of the flat cable in a holder; a connecting step of connecting a core wire exposed from the end portion of the round cable held by the holder and a conductor exposed from the end portion of the flat cable held by the holder; and an exterior forming step of forming a waterproof exterior portion covering, with an insulating resin, the holder, the round cable pulled out from the holder, and the flat cable pulled out from the holder.

According to the aspects of the present application, in the connecting step of connecting the core wire exposed from the end portion of the round cable and the conductor exposed from the end portion of the flat cable, the round cable and the flat cable are pulled out from the holder in the same direction, whereby it can be manufactured using a connecting device such as an ultrasonic welding device regardless of a length of the flat cable.

DETAILED DESCRIPTION

First Embodiment

FIGS. 1A to 5illustrate a first embodiment. A cable connection structure3A according to the first embodiment includes a plurality of round cables W1, a flat cable W2, a holder10for holding end portions of the plurality of round cables W1and the end portion of the flat cable W2, connecting portions20in each of which a core wire1aof each of the round cables W1and a corresponding conductor2aof the flat cable W2are connected, and a mold resin portion21that is a waterproof exterior portion covering an outer circumference of the holder10.

Each of the round cables W1has a round cross section, and includes the core wire1aand an insulating sheath1bcovering the outer circumference of the core wire1a. The core wire1ais exposed from the insulating sheath1bat an end portion of each of the round cables W1.

The flat cable W2has a cross section in a flat rectangular shape, and includes a plurality of tabular conductors2aarranged in parallel at intervals, and an insulating sheath2bcollectively covering the plurality of tabular conductors2a. Each of the conductors2ais exposed from the insulating sheath2bat an end portion of the flat cable W2.

The holder10includes a round cable holder11for holding the end portions of the round cables W1, and a flat cable holder15for holding the end portion of the flat cable W2.

The round cable holder11is formed of an insulating material. As illustrated inFIG. 2, the round cable holder11includes a round cable holder main body12in which a plurality of round cable arrangement grooves12bpartitioned by dividing walls12ais formed in parallel with each other, and a pair of lock frames13protruding from the side end portions of the round cable holder main body12. Each of upper surfaces of the dividing walls12aof the round cable holder main body12is an abutting surface. Each of the round cables W1is arranged in the round cable arrangement groove12bin such a manner that the core wire1aexposed at the end portion protrudes from the round cable holder11.

The flat cable holder15is formed of an insulating material. As illustrated inFIGS. 3A and 3B, the flat cable holder15includes a flat cable holder main body16in which a flat cable arrangement chamber16ais formed, and a pair of lock claws17provided on surfaces exposed by cutout portions16bof the flat cable holder main body16. The distal end side of the flat cable arrangement chamber16aof the flat cable holder main body16in the crosswise direction is partitioned by a plurality of partition walls16c. An upper surface of a side wall16dof the flat cable holder main body16is a flush surface. The portion of the flat cable arrangement chamber16apartitioned by the partition wall16cis opened to the outside in the state of the holder10in which the round cable holder11and the flat cable holder15are joined together. At the time of ultrasonic welding, a horn33of an ultrasonic welding device30is inserted from the portion opened to the outside of the holder10. On the back side of the flat cable holder main body16, a plurality of through holes16eopened to the position of the flat cable arrangement chamber16apartitioned by the partition wall16cis formed. At the time of ultrasonic welding, an anvil34of the ultrasonic welding device30is inserted from the through hole16e. The flat cable W2is arranged in the flat cable arrangement chamber16ain such a manner that respective conductors2aexposed at the end portion of the flat cable W2are positioned at respective portions partitioned by the partition walls16c.

As illustrated inFIG. 4, the round cable holder11and the flat cable holder15are joined together by abutting the upper surfaces of the dividing walls12aof the round cable holder main body12and a surface of the flat cable W2arranged in the flat cable arrangement chamber16a. Accordingly, the round cable holder11and the flat cable holder15are joined together in such a manner that the round cables W1from the round cable holder11and the flat cable W2from the flat cable holder15overlap with each other and are pulled out in the same direction. Further, the end portions of the round cables W1and the end portion of the flat cable W2are arranged to overlap each other, and are exposed to the outside.

The mold resin portion21is formed of an insulating resin. The mold resin portion21collectively covers, with no gap left, the outer exposed surface of the round cable holder11, the outer exposed surface of the flat cable holder15, the outer circumference of each of the round cables W1pulled out from the round cable holder11, and the outer circumference of the flat cable W2pulled out from the flat cable holder15.

In the cable connection structure3A according to the first embodiment, the mold resin is firmly attached onto, with no gap left, the outer circumference surface of each of the round cables W1and the outer circumference surface of the flat cable W2at the positions of the round cables W1pulled out from the mold resin portion21to the outside and the position of the flat cable W2also pulled out from the mold resin portion21to the outside, thereby securing waterproof property of the connecting portion20.

The holder10includes the round cable holder11and the flat cable holder15, and the round cables W1are held by the round cable holder11while the flat cable W2is held by the flat cable holder15, thereby achieving good workability of holding cables with the holder10.

Next, a manufacturing method of the cable connection structure3A according to the first embodiment will be described. The manufacturing method of the cable connection structure3A is performed in the order of a cable setting step, a connecting step, and an insert resin molding step that is an exterior forming step. The cable setting step includes a cable holding step and a holder combining step. Hereinafter, the manufacturing method of the cable connection structure3A will be described in order.

In the cable holding step, the round cables W1are held in the round cable holder11, and the flat cable W2is held in the flat cable holder15. Specifically, as illustrated inFIG. 2, a plurality of round cables W1is arranged in the round cable arrangement grooves12bof the round cable holder11in such a manner that the core wire1aexposed from the end portion of each of the round cables W1protrudes outside the round cable holder11(round cable holding step). Further, as illustrated inFIGS. 3A and 3B, the flat cable W2is arranged in the flat cable arrangement chamber16ain such a manner that the conductors2aexposed from the end portion of the flat cable W2are positioned at the flat cable arrangement chamber16apartitioned by the partition walls16c(flat cable holding step). The round cable holding step with respect to the round cable holder11and the flat cable holding step with respect to the flat cable holder15may be performed in no particular order, and may be performed simultaneously.

In the holder combining step, the round cable holder11and the flat cable holder15are joined together. Specifically, as illustrated inFIG. 4, the upper surfaces of the dividing walls12aof the round cable holder main body12and the surface of the flat cable W2arranged in the flat cable arrangement chamber16aare abutted each other, and the lock claws17are locked to the lock frames13. In the state where the round cable holder11and the flat cable holder15are joined together, the core wires1aexposed from the end portions of the plurality of round cables W1and the conductors2aexposed from the end portion of the flat cable W2are arranged to overlap each other, and are exposed to the outside. The round cables W1and the flat cable W2from the combined round cable holder11and the flat cable holder15are pulled out to overlap each other in the same direction.

In the connecting step, the round cables W1and the flat cable W2are electrically connected by ultrasonic welding using the ultrasonic welding device30. As illustrated inFIG. 5, the ultrasonic welding device30includes the anvil34, and the horn33arranged at the position facing the anvil34. The horn33is provided at the distal end of an arm portion32whose base end portion is supported by a device main body31.

Specifically, in the connecting step, the round cables W1and the flat cable W2pulled out from the combined round cable holder11and the flat cable holder15are not arranged in the space between the horn33and the device main body31, but are arranged in the open space on the opposite side, in such a manner that the combined round cable holder11and the flat cable holder15are positioned on the anvil34. Then, by the branched horn33, ultrasonic vibration is applied (in the direction of the arrow inFIG. 5) to, while pressure is applied, the position in which the core wires1aof the round cables W1and the conductors2aof the flat cable W2overlap each other. As a result, the core wires1aof the round cables W1and the conductors2aof the flat cable W2are connected by the ultrasonic welding, respectively.

In the insert resin molding step, insert resin molding is performed with the round cable holder11, the flat cable holder15, the round cables W1pulled out from the round cable holder11, and the flat cable W2pulled out from the flat cable holder15serving as inserts, and the mold resin portion21is molded. In this manner, the cable connection structure3A as illustrated inFIGS. 1A and 1Bis produced.

As described above, the cable connection structure3A according to the first embodiment includes the round cables W1each having a round cross section and including the core wire1aand the round insulating sheath1bcovering the outer circumference of the core wire1a, the flat cable W2having a cross section in a flat rectangular shape and including the tabular conductors2aand the flat insulating sheath2bcovering the conductors2a, the holder10holding the end portions of the round cables W1and the end portion of the flat cable W2and pulling out the round cables W1and the flat cable W2in the same direction in an overlapped state, the connecting portions20in which the core wires1aexposed from the end portions of the round cables W1and the conductors2aexposed from the end portion of the flat cable W2held by the holder10are connected, and the mold resin portion21as a waterproof exterior portion that collectively covers the outer circumference of the holder10and the outer circumference of the round cables W1and the flat cable W2pulled out from the holder10. In the step of connecting the core wires1aof the round cables W1and the conductors2aof the flat cable W2, the round cables W1and the flat cable W2are pulled out from the holder10in the same direction, whereby it can be manufactured using a connecting device such as the ultrasonic welding device30regardless of a length of the flat cable W2.

Second Embodiment

FIGS. 6A to 8Billustrate a second embodiment. A cable connection structure3B according to the second embodiment is different from the cable connection structure3A according to the first embodiment in the following points. That is, as illustrated inFIGS. 6A and 6B, in the cable connection structure3B according to the second embodiment, a flat cable W2is bent to be guided in the direction different from the pulled-out direction from a flat cable holder15, specifically, in the diametrically opposite pulled-out direction. Round cables W1and the flat cable W2are pulled out from a mold resin portion21in different directions, specifically, in the directions diametrically opposed to each other.

Other configurations in the second embodiment are the same as those in the first embodiment, and the same constituent elements are denoted by the same reference signs to omit redundant descriptions.

As illustrated inFIGS. 8A and 8B, in the cable connection structure3B according to the second embodiment, mold resin is firmly attached onto, with no gap left, the outer circumference surface of each of the round cables W1and the outer circumference surface of the flat cable W2at the position of the round cables W1pulled out from the mold resin portion21to the outside and the position of the flat cable W2also pulled out from the mold resin portion21to the outside, thereby securing waterproof property of the connecting portions20.

Next, a manufacturing method of the cable connection structure3B according to the second embodiment will be described. In the manufacturing method of the cable connection structure3B according to the second embodiment, a cable setting step (cable holding step and holder combining step) and a connecting step are performed in a similar manner to those in the first embodiment, and thus descriptions thereof will be omitted. The manufacturing method of the cable connection structure3B according to the second embodiment is different from the first embodiment only in an insert resin molding step. That is, as illustrated inFIG. 7, in the insert resin molding step, insert resin molding is performed in such a manner that the flat cable W2is bent to be guided in the direction different from the pulled-out direction from the flat cable holder15, specifically, set in the diametrically opposite pulled-out direction, and the mold resin portion21is molded. In this manner, the cable connection structure3B according to the second embodiment as illustrated inFIGS. 6A and 6Bis produced.

Third Embodiment

FIGS. 9A to 18illustrate a third embodiment. A cable connection structure3C according to the third embodiment includes a plurality of round cables W1, a flat cable W2, a holder10A for holding end portions of the plurality of round cables W1and the end portion of the flat cable W2, connecting portions20in which core wires1aof the round cables W1and conductors2aof the flat cable W2are connected respectively, and a heat shrinkable tube24to which a hot melt adhesive (thermoplastic adhesive)23is attached and which is a waterproof exterior portion covering the outer circumference of the holder10A.

Each of the round cables W1has a round cross section, and includes the core wire1aand an insulating sheath1bcovering the outer circumference of the core wire1a. The core wire1ais exposed from the insulating sheath1bat the end portion of each of the round cables W1.

The flat cable W2has a cross section in a flat rectangular shape, and includes a plurality of tabular conductors2aarranged in parallel at intervals, and an insulating sheath2bcollectively covering the plurality of tabular conductors2a. Each of the conductors2ais exposed from the insulating sheath2bat the end portion of the flat cable W2.

The holder10A is formed of an insulating material. As illustrated inFIGS. 10A and 10B, the holder10A includes a plurality of round cable arrangement grooves26provided on one side of a base wall25, and a flat cable arrangement chamber27provided on the other side of the base wall25.

The upper side of each of the round cable arrangement grooves26is opened. The round cable arrangement grooves26are partitioned by dividing walls25ain the crosswise direction. The distal end side of each of the round cable arrangement grooves26in the crosswise direction is partitioned by partition walls25b. At the time of ultrasonic welding, the horn33of the ultrasonic welding device30is inserted from the opening portions above the partition walls25b. Each of the round cables W1is arranged in the corresponding round cable arrangement groove26in such a manner that the core wire1aexposed at the end portion is positioned at the portion partitioned by the partition walls25b.

The flat cable arrangement chamber27is formed to be surrounded by the base wall25and a surrounding wall28covering the lower part of the base wall25. The partition walls25bextend toward the distal end side of the flat cable arrangement chamber27in the crosswise direction. The distal end side of the flat cable arrangement chamber27is partitioned in the crosswise direction by the partition walls25b. A plurality of through holes28aopened to the flat cable arrangement chamber27is formed at the position on the surrounding wall28where the partition walls25bare positioned. At the time of ultrasonic welding, the anvil34of the ultrasonic welding device30is inserted from the through holes28a. The flat cable W2is arranged in the flat cable arrangement chamber27in such a manner that the conductors2aexposed at the end portion are positioned at the portions partitioned by the partition walls25b.

On the base wall25, a pair of hooking claws29is provided to protrude from the position on the side opposite to the direction in which the flat cable W2is inserted into the flat cable arrangement chamber27.

The round cables W1and the flat cable W2held by the holder10A are pulled out from the holder10A in the same direction. The end portion of each of the round cables W1and the end portion of the flat cable W2are arranged to overlap each other.

On the inner circumference surface of the heat shrinkable tube24, the hot melt adhesive (insulating resin)23, which is a thermoplastic adhesive, is attached over the entire region. The hot melt adhesive23is thermally melted by heating to the heat shrinkable tube24to collectively cover the outer exposed surface of the holder10A and the outer circumference of the round cables W1and the flat cable W2pulled out from the holder10A with no gap left, and is solidified. The heat shrinkable tube24is made in the shrunk state, and covers the outer circumference of the solidified hot melt adhesive23with no gap left.

In the cable connection structure3C according to the third embodiment, the hot melt adhesive (insulating resin)23is firmly attached to, with no gap left, the outer circumference surface of each of the round cables W1and the outer circumference surface of the flat cable W2at the position of the round cables W1pulled out from the hot melt adhesive23to the outside and the position of the flat cable W2also pulled out from the hot melt adhesive23to the outside, thereby securing waterproof property of the connecting portion20.

Next, a manufacturing method of the cable connection structure3C according to the third embodiment will be described. The manufacturing method of the cable connection structure3C according to the third embodiment is performed in the order of a cable setting step, a connecting step, and a tube shrinking step that is an exterior forming step. Hereinafter, the manufacturing method of the cable connection structure3C according to the third embodiment will be described in order.

In the cable setting step, as illustrated inFIG. 11, the end portion of the flat cable W2as an insertion distal end is inserted into the flat cable arrangement chamber27of the holder10A. Then, as illustrated inFIGS. 12A and 12B, the end portion of the flat cable W2is arranged in the flat cable arrangement chamber27in such a manner that the conductors2aexposed at the end portion of the flat cable W2are positioned at the positions exposed from the upper openings of the partition walls25b(positions above the through holes).

Next, the round cables W1are inserted into the round cable arrangement grooves26from above the holder10A. Then, as illustrated inFIGS. 13A and 13B, the round cables W1are arranged in the round cable arrangement grooves26such that the core wires1aexposed at the end portions of the round cables W1are positioned to be exposed from the upper openings of the partition walls25b(positions above the conductors2a). The flat cable W2and the round cables W1may be set in the holder10A in no particular order. They may be set simultaneously.

The core wires1aexposed at the end portions of the round cables W1and the conductors2aexposed at the end portion of the flat cable W2are arranged to overlap each other, and the overlapping portions are exposed from the holder10A to the outside. The round cables W1and the flat cable W2are pulled out from the holder10A to overlap each other in the same direction.

In the connecting step, the round cables W1and the flat cable W2are electrically connected by ultrasonic welding using the ultrasonic welding device30. As illustrated inFIG. 14, the ultrasonic welding device30includes the anvil34, and the horn33arranged at the position facing the anvil34. The horn33is provided at the distal end of an arm portion32whose base end portion is supported by a device main body31.

As illustrated inFIG. 14, in the connecting step, the round cables W1and the flat cable W2pulled out from the holder10A are not arranged in the space between the horn33and the device main body31, but are arranged in the open space on the opposite side, in such a manner that the holder10A is positioned on the anvil34. Then, by the branched horn33, ultrasonic vibration is applied (in the direction of the arrow inFIG. 14) to, while pressure is applied, the position in which the core wires1aexposed at the end portions of the round cables W1and the conductors2aexposed at the end portion of the flat cable W2overlap each other. As a result, the core wires1aof the round cables W1and the conductors2aof the flat cable W2are connected by the ultrasonic welding.

In the tube shrinking step, first, the flat cable W2is bent in the direction indicated by the broken line arrow inFIG. 15, and then made in the state of being guided in the direction different from the pulled-out direction from the holder10A, specifically, in the diametrically opposite pulled-out direction as illustrated inFIG. 16. Then, as illustrated inFIGS. 17A and 17B, the holder10A with the round cables W1and the flat cable W2pulled out from mutually different directions is inserted into the heat shrinkable tube24.

Next, the heat shrinkable tube24and the hot melt adhesive23are heated. Then, as illustrated inFIG. 18, the heat shrinkable tube24shrinks while the hot melt adhesive23melts (fluidizes). The molten hot melt adhesive23is firmly attached onto, with no gap left, the outer exposed surface of the holder10A, the connecting portions20in which the core wires1aof the round cables W1and the conductors2aof the flat cable W2held by the holder10A are connected, the outer circumference of the holder10A, and the outer circumference of the round cables W1and the flat cable W2pulled out from the holder10A, and is solidified by cooling in the adhered state. As a result, the solidified hot melt adhesive23collectively covers the outer exposed surface of the holder10A, the connecting portions20in which the core wires1aof the round cables W1and the conductors2aof the flat cable W2held by the holder10A are connected, the outer circumference of the holder10A, and the outer circumference of the round cables W1and the flat cable W2pulled out from the holder10A, and the heat shrinkable tube24covers the outer circumference of the hot melt adhesive23with no gap left. In this manner, the cable connection structure3C according to the third embodiment as illustrated inFIGS. 9A and 9Bis produced.

As described above, the cable connection structure3C according to the third embodiment includes the round cables W1each having a round cross section and including the core wire1aand the round insulating sheath1bcovering the outer circumference of the core wire1a, the flat cable W2having a cross section in a flat rectangular shape and including the tabular conductors2aand the flat insulating sheath2bcovering the conductors2a, the holder10A holding the end portions of the round cables W1and the end portion of the flat cable W2and pulls out the round cables W1and the flat cable W2in the same direction in an overlapped state, the connecting portions20in which the core wires1aexposed from the end portions of the round cables W1and the conductors2aexposed from the end portion of the flat cable W2held by the holder10A are connected, and the heat shrinkable tube24to which the hot melt adhesive23is attached as a waterproof exterior portion that collectively covers the outer circumference of the holder10A and the outer circumference of the round cables W1and the flat cable W2pulled out from the holder10A. In the step of connecting the core wires1aof the round cables W1and the conductors2aof the flat cable W2, the round cables W1and the flat cable W2are pulled out from the holder10in the same direction, whereby it can be manufactured using a connecting device such as the ultrasonic welding device30regardless of a length of the flat cable W2.

In the cable connection structure3A according to the first embodiment and the cable connection structure3B according to the second embodiment, the holder10is divided into the round cable holder11and the flat cable holder15. However, it may be one component.

In the cable connection structure3C according to the third embodiment, the holder10A is one component. However, the holder10A may be two components as in the cable connection structure3A according to the first embodiment and the cable connection structure3B according to the second embodiment.

In the cable connection structure3C according to the third embodiment, the tube shrinking step is performed in such a manner that the flat cable W2is bent to be guided in the direction different from the pulled-out direction from the holder10A and set. However, as in the first embodiment, the flat cable W2may not be bent, and the tube shrinking step (heating with respect to heat shrinkable tube24and hot melt adhesive23) may be performed while the flat cable W2and the round cables W1are pulled out from the holder10A in the same direction.

In the cable connection structure3C according to the third embodiment, the heat shrinkable tube24that changes its shape by thermal action is used. However, it may be a shrinkable tube that changes its shape by the action of light or the like.

In the first to third embodiments, the core wires1aof the round cables W1and the conductors2aof the flat cable W2are connected by ultrasonic welding using the ultrasonic welding device30. However, it is only necessary to use a connecting device capable of electrically connecting the core wires1aof the round cables W1and the conductors2aof the flat cable W2, which may be, for example, a resistance welding device.