JP2022135164A - Conductor joint structure and conductor ultrasonic joint method - Google Patents

Abstract

To provide a conductor joint structure and a conductor ultrasonic joint method which enable efficient joint of conductors by ultrasonic joint.SOLUTION: A conductor ultrasonic joint device 1 has an anvil 7, a horn 5 arranged so as to face the anvil 7, and a vibration source 3 which is connected to one end of the horn 5 and imparts vibration to the horn 5. A vertical direction of an aggregation of the conductor 15 is sandwiched between the anvil 7 and the horn 5, and a width direction thereof is sandwiched between a pair of gathers 9. Ultrasonic vibration is imparted to the aggregate through the horn 5 from the vibration source 3 while sandwiching the aggregate between the anvil 7 and the horn 5 from the vertical direction and collectively pressurizing the aggregate in a state where the width direction of the aggregate is sandwiched between the gathers 9 and is restricted. At this time, a height of the anvil 7 on a side distant from the vibration source 3 is set to be higher than a height of the anvil 7 on a side close to the vibration source 3.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a conductor bonding structure in which conductors of a plurality of electric wires are ultrasonically bonded together, and a conductor ultrasonic bonding method.

A wire harness used in an automobile or the like is used by joining a plurality of electric wires. For joining such electric wires, for example, the insulation coating of each of a plurality of electric wires is peeled off to expose the core wire, the tips of the core wires are aligned and overlapped, and in this state, the core wires are sandwiched. Thus, there is a method of joining core wires together by ultrasonic joining or the like (for example, Patent Document 1).

International Publication 2019/225492

FIG. 6A is a schematic diagram showing a general ultrasonic bonding apparatus 100. FIG. The ultrasonic bonding apparatus 100 mainly includes a horn 105, an anvil 107, a gather 109, a vibration source 103, and the like. One end of the horn 105 arranged to face the anvil 107 is connected to the vibration source 103 .

A plurality of conductors 111 are positioned between anvil 107 and horn 105 . Gathers 109 are arranged on both sides of the plurality of conductors 111 . In addition, the conductor 111 is configured by, for example, twisting a plurality of strands.

Next, as shown in FIG. 6B, with the conductor 111 placed on the anvil 107, both sides of the conductor 111 are sandwiched between the gathers 109, and the horn 105 is lowered from above to sandwich the conductor 111. In this state, while the horn 105 presses the conductor 111 from above (arrow X in the figure), vibration (ultrasonic vibration) is generated by the vibration source 103, and the conductors 111 vibrate together via the horn 105. By adding the middle arrow Y), the conductors 111 are joined to form a joint 113 .

However, when the horn 105 presses the conductor 111 , the horn 105 receives a reaction force from the conductor 111 . Here, since the horn 105 is in a cantilever state with respect to the vibration source 103, this reaction force causes the horn 105 to warp (arrow Z in the figure) such that the side far from the vibration source 103 is lifted upward. do. In the drawing, the horn 105 is shown to be greatly warped for ease of explanation, but in some cases, the warping may not be noticeable to the naked eye.

Such warping causes a difference in the transmission of the pressing force to the conductor 111 between the side closer to the vibration source 103 and the side farther from the vibration source 103 . For example, on the side closer to the vibration source 103, the effect of warping of the horn 5 is small, and the designed pressing force can be transmitted to the conductor 111, but on the side far from the vibration source, the conductor 111 is sufficiently pressed. Pressure may not be transmitted. In particular, in ultrasonic bonding, when the conductors 111 are pressed against each other and ultrasonic vibration is applied, the ultrasonic vibration propagates between the conductors and integrates the two. If it becomes weak, it becomes difficult for ultrasonic vibrations to propagate, and the joining force immediately drops.

FIG. 7 is a conceptual diagram showing a joint 113 obtained by a conventional method. As described above, since the warp amount of the horn 105 is not large, the joint 113 looks substantially rectangular at first glance. is likely to occur. For this reason, it becomes a factor of deterioration of the yield at the time of manufacture.

The present invention has been made in view of such problems, and an object of the present invention is to provide a conductor bonding structure and a conductor ultrasonic bonding method capable of efficiently bonding conductors by ultrasonic bonding. .

In order to achieve the above-described object, a first invention is a joint structure in which conductors of a plurality of electric wires are ultrasonically joined together, wherein the joint of the conductor is in the ultrasonic joining direction when viewed from the axial direction of the electric wire. and the width direction of the joint portion is defined as the direction perpendicular to the thickness direction, the thickness of the joint portion is inclined from one side to the other side in the width direction and changes. It is a joint structure of a conductor that

It is desirable to include at least one wire made of an aluminum-based conductor.

It is further desirable that the number of electric wires composed of conductors whose main component is aluminum is greater than that of electric wires composed of conductors whose main component is other materials.

Neither the upper surface nor the lower surface in the thickness direction may be perpendicular to the side surface in the width direction of the joint portion.

According to the first invention, in the cross section perpendicular to the axial direction of the electric wire, the ultrasonically welded joint is not rectangular, but is inclined from one side to the other side in the width direction. Therefore, a larger pressing force can be applied to the thinner side. For this reason, it is possible to suppress strand spillage at least on the thin side.

In addition, the effect of the present invention is particularly great in a conductor whose main component is aluminum, because the conductor is easily deformed. For this reason, if the number of conductors whose main component is aluminum is greater than that of conductors whose main component is other materials (for example, if all the wires are composed of conductors whose main component is aluminum), , a greater effect can be obtained.

In addition, neither the anvil side nor the horn side is perpendicular to the pressing direction, and the ultrasonic bonding is performed by an inclined surface, so that neither the upper surface nor the lower surface is formed substantially perpendicular to the side surface. be. For this reason, a larger pressing force can be applied to one of the thinner sides, and the spillage of the strands on the thinner side can be suppressed.

A second invention is a method for ultrasonically joining conductors of a plurality of electric wires, comprising an anvil, a horn arranged opposite to the anvil, and a vibration source connected to one end of the horn to vibrate the horn. and, when an assembly in which a plurality of electric wires are assembled is sandwiched between the anvil and the horn and the vibration is applied while applying pressure, the distance between the anvil and the horn on the far side from the vibration source is 2. A method for ultrasonically bonding a conductor, wherein the distance between the anvil closer to the vibration source and the horn is narrower than the distance between the horn and the anvil.

The height of the anvil farther from the vibration source may be set higher than the height of the anvil closer to the vibration source.

A height of the horn farther from the vibration source may be set to be lower than a height of the horn closer to the vibration source.

According to the second invention, since the distance between the anvil and the horn on the far side from the vibration source is narrower than the distance between the anvil and the horn on the near side from the vibration source, the conductor is more reliably secured on the side far from the vibration source. can be pressed for ultrasonic bonding. Therefore, it is possible to reliably join the conductors together while suppressing the occurrence of wire spillage or the like.

As such a method, the height of the anvil on the far side from the vibration source may be set higher than the height of the anvil on the side close to the vibration source, or the height of the horn on the side far from the vibration source may be set. height may be set to be lower than the height of the horn on the side closer to the vibration source.

ADVANTAGE OF THE INVENTION According to this invention, the joining structure of a conductor and the ultrasonic joining method of a conductor which can join conductors efficiently by ultrasonic joining can be provided.

The figure which shows the joining structure 10. FIG. (a) is a diagram showing a joint portion 13, and (b) is an enlarged view of the I portion of (a). (a), (b) is a figure which shows the joining method of the conductor 15. FIG. (a), (b) is a figure which shows the other joining method of the conductor 15. FIG. (a) is a figure which shows the junction part 13a, (b) is a figure which shows the junction part 13b. (a) and (b) are diagrams showing a conventional bonding method of a conductor 111. FIG. FIG. 2 is a conceptual diagram showing a conventional joint 113;

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a junction structure 10. As shown in FIG. The joint structure 10 is obtained by ultrasonically joining conductors 15 of a plurality of electric wires 17 to each other. The electric wire 17 is configured by covering the outer periphery of the conductor 15 with an insulating coating. A predetermined range of insulation coating is removed from the end of the electric wire 17 to expose the inner conductor 15 . The conductor 15 is configured by twisting a plurality of conductor strands. Note that the conductor 15 may be a single wire.

Materials such as aluminum (aluminum or aluminum alloy) or copper (copper or copper alloy) can be applied to the conductor 15. At least the electric wire 17 made of the conductor 15 whose main component is aluminum (so-called pure aluminum) is used. It is desirable to include one wire, and the number of wires 17 composed of conductors 15 mainly composed of aluminum is more than the number of wires 17 composed of conductors 15 mainly composed of other materials (for example, aluminum alloy, copper, or copper alloy). is desirable. For example, in the case of the aluminum-based conductor 15, although it is relatively soft compared to copper-based materials, if the oxide film is strong and vibrations are not easily transmitted, the oxide film is not removed and the joint is likely to be insufficient. Therefore, this embodiment is particularly effective for aluminum (especially pure aluminum-based) materials.

The conductors 15 of the plurality of electric wires 17 are arranged in the same direction, and the joints 13 are formed by ultrasonically joining the conductors 15 to each other at the distal ends of the conductors 15 . That is, the conductor 15 is integrated at the joint 13 . Note that the directions of the electric wires 17 do not necessarily have to be the same.

FIG. 2(a) is a diagram of the electric wire 17 (joint portion 13) viewed from the distal end side in the axial direction. Here, although the details will be described later, the vertical direction in the figure is the ultrasonic bonding direction, this direction is the thickness direction of the bonding portion 13, and the direction orthogonal to this (horizontal direction in the figure) is the width of the bonding portion 13. direction. At this time, the thickness of the joint portion 13 changes so as to be inclined from one side in the width direction to the other side.

In the illustrated example, the thickness gradually (linearly) increases from one side (C in the figure) in the width direction toward the other side (D in the figure). That is, the upper and lower surfaces of the joint 13 are not parallel. Both side surfaces of the joint portion 13 are substantially parallel to each other. Also, the angle between the upper surface and the side surface of the joint portion 13 (angles G and H in the drawing) is substantially vertical. On the other hand, the angle between the bottom surface and the side surface of the joint 13 (angles E and F in the figure) is not perpendicular. That is, the shape of the joint portion 13 in a cross section perpendicular to the axial direction is substantially trapezoidal.

In addition, FIG.2(b) is an I section enlarged view of Fig.2 (a). As described above, since the vertical direction of the bonding portion 13 in the drawing is the ultrasonic bonding direction, the upper and lower surfaces are the contact surfaces between the anvil and the horn. At this time, since the anvil and the horn are formed with fine uneven surfaces, unevenness is formed in the width direction on the upper and lower surfaces as shown in FIG. 2(b). Although illustration of the lower surface side is omitted, an uneven shape similar to that of the upper surface is formed. In this way, the ultrasonic bonding method is applied to the facing surface on which the concave-convex shape formed by the mold is formed.

Here, the bottoms of the recesses on the upper and lower surfaces are formed by pressing of the mold at the contact portions of the anvil or horn. On the other hand, the convex portions on the upper and lower surfaces are formed by partially deforming and entering the concave portions of the mold. Therefore, the positions (depths) of the concave portions on the upper and lower surfaces are substantially constant (linear), but the heights of the convex portions on the upper and lower surfaces are not necessarily constant. Therefore, it is desirable that the reference of the thickness and the angle of the upper and lower surfaces is based on the concave portion of the concave-convex shape.

It is desirable that the thickness difference (DC) in the width direction is 10% or more of the width W. That is, it is desirable that the thickness of the thinner side is C=D−W×10%. Note that this embodiment is particularly effective when the thick side D is 1.5 mm or less.

Next, a method for ultrasonically bonding the conductors 15 of the electric wires 17 using an ultrasonic bonding apparatus will be described. FIG. 3(a) is a diagram showing an ultrasonic bonding apparatus 1 for forming conductors 15 by ultrasonic bonding. The ultrasonic bonding apparatus 1 has an anvil 7 , a horn 5 facing the anvil 7 , and a vibration source 3 connected to one end of the horn 5 to vibrate the horn 5 .

First, an assembly in which conductors 15 of a plurality of electric wires 17 are assembled is arranged between anvil 7 and horn 5 facing each other in the vertical direction. Gathers 9 are arranged on both sides of the aggregate of conductors 15 . That is, the aggregate of the conductors 15 is sandwiched between the anvil 7 and the horn 5 in the vertical direction, and sandwiched between the pair of gathers 9 in the width direction.

Next, in a state in which the width direction of the aggregate is sandwiched and regulated by the gathers 9, as shown in FIG. (in the direction of arrow A in the figure), and ultrasonic vibrations (in the direction of arrow B in the figure) are applied to the assembly from the vibration source 3 via the horn 5 .

At this time, the height of the anvil 7 farther from the vibration source 3 is set to be higher than the height of the anvil 7 closer to the vibration source 3 . That is, the distance between the anvil 7 and the horn 5 on the far side from the vibration source 3 is narrower than the distance between the anvil 7 and the horn 5 on the side near the vibration source 3 . Therefore, it is possible to more reliably pressurize the conductor assembly on the side far from the vibration source 3 .

As described above, the horn 5 is slightly warped in the direction in which the side far from the vibration source 3 is separated from the anvil 7 . However, the height difference in the width direction caused by this warp is equal to or less than the height difference of the slope formed on the anvil 7 (more preferably, it is smaller than the height difference of the slope formed on the anvil 7). Therefore, even if the horn 5 is warped to some extent (for example, even if the angles G and H in FIG. 2(a) are not vertical but are inclined downward to the left in the drawing), the horn 5 is separated from the vibration source 3. Vibration can be propagated by efficiently compressing the conductor 15 on the opposite side.

As described above, the conductors 15 are joined together to form the joining portion 13 . As described above, in the joint 13 obtained in this way, the direction sandwiched between the anvil 7 and the horn 5 (that is, the ultrasonic welding direction) is the thickness direction of the joint 13, and the direction perpendicular to this direction. (the direction sandwiched by the gathers 9 ) is the width direction of the joint portion 13 .

As described above, according to the first embodiment, when the plurality of electric wires 17 are joined by ultrasonic welding, the upper surface of the anvil 7 has a height with respect to the supporting direction (ultrasonic vibration direction) of the horn 5. By forming an inclined surface that varies, it is possible to suppress strand spillage at the ends of the joint portion 13 in the width direction. Therefore, an efficient and highly reliable conductor bonding structure can be formed by ultrasonic bonding.

It is difficult to immediately determine which direction in the width direction is closer to or farther from the vibration source 3 from the joint 13 after joining. However, if the thinner side of the joint 13 is closer to the vibration source 3 in the width direction, combined with the warp of the horn 5, the pressing force on the side farther from the vibration source 3 becomes smaller. As a result, for example, the conductor 15 does not sufficiently enter the concave portion of the mold on the side where the pressing force is weak with respect to the uneven mold shape formed on the anvil 7 or the horn 5, and the height of the convexity of the upper and lower surfaces is increased. tends to be lower. Therefore, in the upper and lower surfaces of the joint portion 13 , the side with the lower convex height is considered to be the side farther from the vibration source 3 .

In addition, when the height of the convex portion is substantially constant in the width direction, it means that a sufficient pressing force is applied to the whole. For this reason, in the conventional art, the height of the projection on the far side from the vibration source 3 tends to be low, whereas the fact that the entirety is pressed substantially uniformly means that the thin side of the joint 13 has a smaller thickness. , on the far side from the vibration source 3.

Further, by observing the end surface of the joint 13, it is possible to grasp the boundary between the strands forming the original conductor (that is, each strand after compression). Here, if the thinner side of the joint portion 13 is closer to the vibration source 3, the pressing force on the side farther from the vibration source 3 is smaller, so the amount of compression of the conductor at this portion is smaller. For this reason, when the original strands have the same diameter, for example, the size of the strand after compression on the side with the smaller amount of compression is compared with the size of the strand after compression on the side with the larger amount of compression. become relatively large. Therefore, if the thinner side of the joint 13 is closer to the vibration source 3, the size of the wire on the thicker side of the joint 13 after compression tends to be large (that is, the amount of compression is small). be.

On the other hand, if the wires are uniformly compressed in the width direction of the joint portion 13, the wires are compressed substantially uniformly, so that the size of the wires after compression in the width direction becomes substantially uniform. For this reason, in the conventional art, the wire size on the far side from the vibration source 3 tends to be large. It is considered that the thin side was the side far from the vibration source 3 .

It should be noted that the substantially uniform size of the wires means that the compressibility of all the wires is in the range of 60 to 85%, for example. Here, the compressibility is defined as the cross-sectional area of the wire after compression relative to the cross-sectional area of the wire before compression. The cross-sectional area can be calculated, for example, by image analysis of the cross section. As described above, in the conventional method, even if the compression rate of the strands closer to the vibration source 3 is within the above range, the compression rate of the strands farther from the vibration source 3 may exceed 85%. If compression can be performed substantially uniformly, the compressibility of all wires can be set within the above range.

(Second embodiment)
Next, a second embodiment will be described. FIGS. 4A and 4B are schematic diagrams showing the process of ultrasonically bonding the conductor 15 by the ultrasonic bonding apparatus 1a according to the second embodiment. In the following description, the same reference numerals as those in FIGS. 1 to 3 are given to the structures having the same functions as those in the first embodiment, and overlapping descriptions are omitted.

As shown in FIG. 4( a ), in the second embodiment, the upper surface of the anvil 7 is flat (substantially perpendicular to the gathers 9 ), and the conventional anvil 7 is used as it is. The height of the horn 5 on the far side from the vibration source 3 is set to be lower than the height of the horn 5 on the side close to the vibration source 3.例文帳に追加That is, the lower surface (the surface facing the anvil 7 ) of the horn 5 has an inclined surface that approaches the anvil 7 as it goes away from the vibration source 3 .

In a state in which the width direction of the assembly is sandwiched and regulated by the gathers 9, as shown in FIG. direction of arrow A), and ultrasonic vibration (direction of arrow B in the figure) is applied to the assembly from the vibration source 3 through the horn 5 .

At this time, since the height of the horn 5 on the far side from the vibration source 3 is lower than the height of the horn 5 on the side close to the vibration source 3, the distance between the anvil 7 on the side far from the vibration source 3 and the horn 5 is It is narrower than the interval between the anvil 7 and the horn 5 closer to the vibration source 3. Therefore, it is possible to more reliably pressurize the conductor assembly on the side far from the vibration source 3 .

FIG. 5(a) is a diagram showing the obtained joint 13a. As described above, the vertical direction in the drawing is the ultrasonic bonding direction, this direction is the thickness direction of the bonding portion 13a, and the direction orthogonal to this direction (horizontal direction in the drawing) is the width direction of the bonding portion 13a. The thickness of the joint portion 13a is also not constant, and the thickness changes by being inclined from one side in the width direction to the other side.

More specifically, in the illustrated example, from one side in the width direction (the side far from the vibration source 3 and J in the drawing) toward the other side (the side near the vibration source 3 and K in the drawing) The thickness gradually (linearly) becomes thicker. That is, the upper and lower surfaces of the joint portion 13a are not parallel. Both side surfaces are substantially parallel to each other, and the angles between the lower surface and the side surfaces (angles L and M in the drawing) are substantially perpendicular. On the other hand, the angle between the top surface and the side surface (angles N and O in the figure) is not perpendicular. That is, the shape of the joint portion 13 in a cross section perpendicular to the axial direction is substantially trapezoidal.

As described above, the horn 5 is slightly warped in the direction away from the anvil 7 on the side far from the vibration source 3 . However, the height difference in the width direction caused by this warp is equal to or less than the height difference of the slope formed on the horn 5 (more preferably, it is smaller than the height difference of the slope formed on the horn 5). Therefore, even if the horn 5 is warped to some extent, the conductor 15 on the side away from the vibration source 3 can be efficiently compressed to propagate the vibration.

Although the horn 5 is inclined in this embodiment, the anvil 7 may also be inclined as in the first embodiment. FIG. 5(b) is a diagram showing the joint 13b in which the anvil 7 and the horn 5 are both inclined so that the sides farther from the vibration source 3 are closer to each other and ultrasonically welded.

In this case, gradually (linearly ) thickness increases. Both side surfaces are substantially parallel to each other, and neither the angle between the bottom surface and the side surfaces (angles R, S in the figure) nor the angle between the top surface and the side surfaces (angles T, U in the figure) are perpendicular. That is, neither the upper surface nor the lower surface in the thickness direction is perpendicular to the side surface in the width direction.

As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained. That is, it is possible to suppress the strands from spilling out at the ends of the joints 13a and 13b in the width direction, and to form an efficient and highly reliable conductor joint structure by ultrasonic joining.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not influenced by the above-described embodiments. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. be understood to belong to

For example, the number and arrangement of electric wires are not limited to the example shown in the figure, such as the number of strands constituting a conductor.

Reference Signs List 1, 1a... Ultrasonic bonding device 3... Vibration source 5... Horn 7... Anvil 9... Gathers 10... Joining structures 13, 13a, 13b... Joining portion 15... Conductor 17 Electric wire 100 Ultrasonic bonding device 103 Vibration source 105 Horn 107 Anvil 109 Gather 111 Conductor 113 Joint

Claims (7)

A joint structure in which conductors of a plurality of electric wires are ultrasonically joined together,
When viewed from the axial direction of the electric wire, the ultrasonic bonding direction is the thickness direction of the joint of the conductor, and the direction orthogonal to this is the width direction of the joint, and the thickness of the joint is the width direction. A conductor junction structure characterized in that the inclination changes from one side to the other side of the. 2. The conductor joint structure according to claim 1, further comprising at least one electric wire made of a conductor whose main component is aluminum. 3. The conductor joint structure according to claim 2, wherein the number of electric wires composed of conductors whose main component is aluminum is greater than the number of electric wires composed of conductors whose main component is other materials. 4. The conductor joint structure according to claim 1, wherein neither the upper surface nor the lower surface in the thickness direction is perpendicular to the side surface in the width direction of the joint portion. An ultrasonic bonding method between conductors of a plurality of electric wires,
Using an anvil, a horn arranged opposite to the anvil, and a vibration source connected to one end of the horn to vibrate the horn,
When an assembly in which a plurality of electric wires are assembled is sandwiched between the anvil and the horn and is subjected to vibration while being pressurized, the distance between the anvil and the horn on the far side from the vibration source is the same as the vibration source. A method for ultrasonically bonding a conductor, wherein the distance between the near side anvil and the horn is narrower than the distance between the anvil and the horn. 6. The ultrasonic bonding method for conductors according to claim 5, wherein the height of the anvil on the far side from the vibration source is set to be higher than the height of the anvil on the side close to the vibration source. . 7. The conductor according to claim 5, wherein the height of the horn on the far side from the vibration source is set to be lower than the height of the horn on the side close to the vibration source. Ultrasonic bonding method.

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