JPH10334956A - Laser welded structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simultaneously fuse a bus bar and a tub terminal, and extend the welding range or welding depth of stably increasing the bonding strength by emitting a laser beam to a bonding interface between the pattern part of the bus bar and the bent leg part of the tub terminal so as to weld them together. SOLUTION: A bent leg part 17b of a tub terminal 17a is put on the pattern part of a bus bar 17 on an insulating plate from above, and a laser beam LB is emitted to the bonding interface E1 between an upper surface 17j of the bus bar 17 and a front end surface 17k of the bent leg part 17b from the obliquely upper direction. The laser beam LB is also emitted to the bonding interface E2 between the side end surface 17m of the bus bar 17 and the side end surface 17n of the bent leg part 17b from the exactly horizontal direction. Each bonding interfaces E1, E2 between the bent leg part 17b the tub terminal 17 and the pattern part of the bus bar 17 is fused and welded together (a). Namely, the bus bar and the tub terminal start to be welded at the some time, and the bonding strength is stably increased it the emitting energy for welding is constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding structure most suitable for a bus bar housed in an electric junction box, and more particularly, to a structure capable of stably improving a joining strength.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
A laser beam LB is applied to a crimping portion 3a of a crimping terminal 3 for crimping and connecting the conductor 2 to melt and weld the crimping portion 3a and the conductor 2 (Japanese Patent Application No. 2-1038).
No. 786).

[0003] As shown in FIG. 8 (B), a separate metal projection 5 for replenishing the molten volume is provided on the flat plate-shaped welding metal conductor 4, and a plurality of metal projections are provided below the projection 5. The conductor 2 composed of the element wire 2a is arranged, and the laser beam LB is
Irradiation is performed to fuse and weld the protruding portion 5 together with the conductor 2 (Japanese Patent Laid-Open No. 6-302).
No. 341).

By the way, in an electric junction box used for branch connection of an automobile wire harness or the like to various electric components, the branch connection points are concentrated at one place, and the wiring is rationally and economically connected. With the increase in the density of wire harnesses, various types have been developed according to vehicle types or applications.

[0005] As shown in FIG. 7, the electric connection box is formed by pressing a hoop material 6 with a bus bar 7A using a press die.
To 7C, and each of the bus bars 7A to 7C
The tab terminals 7a and 7b are cut and raised from the pattern portion in the vertical direction, and insulating plates 8A to 8C are interposed between the bus bars 7A to 7C, respectively. And a lower case 9B.

As shown in detail in FIG. 6 of the bus bars 7A to 7C, a tab terminal 7a cut upward from a middle bus bar 7B is connected to an upper insulating plate 8A.
The tab terminals 7a cut upward from the upper bus bar 7A are set so as to have the same height as the tab terminals 7a cut upward from the upper bus bar 7A. The board 8B and the upper insulating plate 8A are penetrated so that the tab terminals 7a cut and raised upward from the upper bus bar 7A are set to have the same height.

Similarly, the tab terminal 7b cut and raised from the middle bus bar 7B extends downward through the lower insulating plate 8C, and the height of the tab terminal 7b cut and raised from the lower bus bar 7C is lowered. The tab terminals 7 which are set so as to be aligned and cut and raised downward from the upper bus bar 7A.
“b” is set so as to penetrate the middle insulating plate 8B and the lower insulating plate 8C, and to have the same height as the tab terminals 7b cut and raised downward from the lower bus bar 7C.

[0010] As shown in FIG. 7, external components such as a fuse 11 and a relay 12 are inserted and connected to the tab terminals 7 a and 7 b via a relay terminal 10 and the like, and externally integrated. The connector on the side is directly inserted and connected.

When the circuit volume in the electric junction box 9 increases, the bus bars 7A (7
B, 7C), the pattern parts of the bus bars 7A to 7C of different levels, and the pattern parts of the bus bars 7A to 7C, and other wiring members (FPC, PC).
B or a conductor such as an electric wire) with a connector.

On the other hand, in recent years, a plurality of electric connection boxes dispersedly mounted in an automobile are integrated into one and arranged in a center cluster or the like, and a wire harness for connecting between the electric connection boxes is provided. Attempts have been made to simplify (line saving).

If the number of circuits in the electric junction box is about 40, a three-layer bus bar laminated structure as described above may be used. However, the number of circuits in the electric junction box is reduced by 80 to 100 due to integration.
When it is increased to the extent, a bus bar laminated structure of 8 to 10 layers is obtained.

With the bus bar laminated structure of eight to ten layers as described above, when the tab terminals are vertically cut from the bus bar pattern portion of each layer, the tab terminals cut and raised upward from the uppermost bus bar are formed. In order to set the height to be the same as the height of the tab terminal cut and raised from the lowermost bus bar, the maximum number of tab terminals is 8 to 1
It is necessary to set the length to penetrate as many as 0 layers of the insulating plate.

However, in order to cut a long tab terminal from the bus bar pattern portion, a space for cutting and raising the tab terminal is required in the pattern portion.
Since this space becomes a dead space and the size of the bus bar cannot be reduced in size and density, there is a problem that the number of stacked bus bars cannot be reduced.

To solve this problem, the applicant has
We have proposed a laser welding structure that makes it possible to reduce the size and density of busbars housed in electrical junction boxes by utilizing laser welding technology.

In the laser welding structure, basically, the tab terminals are not cut and raised in the vertical direction from the bus bar pattern portion, but the tab terminals are formed separately, and the separate tab terminals are connected to the bus bar pattern portion. By irradiating a laser beam, and melting and welding the tab terminal and the pattern portion, a dead space for cutting and raising the tab terminal in the pattern portion of the bus bar becomes unnecessary. By adding a pattern part to
The bus bar can be made smaller and more dense.

[0016]

SUMMARY OF THE INVENTION The present invention relates to an improvement in a laser welding structure proposed by the present applicant, and is particularly suitable for welding a bus bar housed in an electric junction box and having a stable joining strength. An object of the present invention is to provide a laser welding structure that can be improved.

[0017]

In order to solve the above-mentioned problems, in the first aspect of the present invention, an object to be welded is applied to the object to be welded, and the object to be welded is welded with a laser beam. A laser welding structure characterized by irradiating a laser beam from a diagonal direction or a lateral direction to a joint interface between the welded body and the workpiece to be welded. Specifically, as in claim 5, the welded body is a bus bar housed in an electric junction box, the welded body is a tab terminal, and the bent leg portion of the tab terminal is applied to a pattern portion of the bus bar. Accordingly, a laser beam is applied to the joining interface between the pattern portion of the bus bar and the bent leg portion of the tab terminal from a diagonal direction or a sideways direction, and is welded to the bus bar pattern portion.

According to claim 1 (or claim 5), when a laser beam is applied to the bent leg of the tab terminal from directly above (or directly below) and welded, first, the thickness of the plate of the bent leg is reduced. Is melted, the upper surface (or lower surface) of the bus bar starts to be melted, so that the irradiation energy for melting becomes large and the bonding strength is small.

Therefore, by irradiating a laser beam to the joint interface between the pattern portion of the bus bar and the bent leg portion of the tab terminal and welding the same, the bus bar and the tab terminal begin to be melted at the same time. Is the same, the melting range and the melting depth are widened, and the bonding strength is stably increased.

The bonding interface is formed between the upper surface of the bus bar and the end surface of the bent leg of the tab terminal as described in claim 2 (or claim 5).
An end surface of the welding through hole formed between the end surface of the bus bar and the bent leg portion of the tab terminal, and between the end surface of the bus bar and the bent leg portion of the tab terminal. It is preferable that the distance between the respective inner end surfaces is within the range.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the same components and operations as those of the prior art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 shows a laser welding structure according to the first embodiment. The tab terminal 17a does not cut and raise each of the tab terminals 17a in the vertical direction from the pattern portion of the bus bar 17 as in the related art, but separates the tab terminal 17a and integrally forms a bent leg 17b at the lower end of the tab terminal 17a. I do.

The tab terminal 17a is connected to the bent leg 17
b is applied to the pattern portion of the bus bar 17 on the insulating plate from above, and the upper surface 17j of the bus bar 17 and the bent leg 1
The laser beam LB is applied to the joint interface E1 between the front end face 17k and the front end face 17b from an obliquely upward direction.

Further, a laser beam LB is applied to the joining interface E2 between the side end face 17m of the bus bar 17 and the side end face 17n of the bent leg 17b from just beside. The irradiation of the laser beam LB may be performed on one of the bonding interfaces E1 and E2.

By this irradiation, the respective joint interfaces E1 and E2 between the bent leg portion 17b of the tab terminal 17a and the pattern portion of the bus bar 17 are melted and welded.

As shown in the comparative example of FIG.
When the laser beam LB is applied from directly above to the bent leg portion 17b and welded, the upper surface 17j of the bus bar 17 starts to be melted after the plate thickness T of the bent leg portion 17b is melted. And the bonding energy is large.

Therefore, as described above, the laser beam LB is applied to the joint interfaces E1 and E2 between the pattern portion of the bus bar 17 and the bent leg portion 17b of the tab terminal 17a to perform welding, thereby obtaining the structure shown in FIGS. 4), the bus bar 17 and the bent leg portion 17b of the tab terminal 17a start to be melted at the same time. Therefore, if the irradiation energy for melting is the same as that of the comparative example of FIG. It becomes wider and the bonding strength increases stably.

All the tab terminals 17a of the bus bar 17
Are not welded separately, but if necessary, the tab terminals 17a
Can be used in combination with each other.

Further, as shown in FIG.
When the relay terminal 17c is integrally formed with the 7a, a separate relay terminal is not required.

When the bus bar 17 is welded by conventional resistance welding, a large jig is required for each bus bar in order to sandwich the bus bar between the electrodes. Not suitable for In the case of conventional arc welding, since the gap between the busbar and other circuits is narrow, it is necessary to insulate or widen the gap, so that the density cannot be increased, and it is necessary to ground each circuit to be welded. Therefore, processing man-hours and the like become expensive, which is not suitable for mass production. Furthermore, in ultrasonic welding, partial plating is necessary because welding cannot be performed on a portion of the bus bar that has plating, and the bus bar shape is different one by one, so jigs are required for the number of circuits, so processing man-hours and equipment are required. However, they are expensive and unsuitable for mass production.

On the other hand, in the case of the laser welding of the present invention, the laser beam LB is not in contact with the laser beam LB, so that the laser beam LB is non-contact compared with the above-described resistance welding, arc welding, ultrasonic welding and the like. The bus bar 17 can be welded to
Since the welding seconds per location are short, mass productivity is good, and since the laser beam LB has a small beam diameter, the pitch between the bus bar 17 and the tab terminal 17a can be narrowed to improve the degree of freedom in design wiring. There is an advantage of doing so.

Among various laser weldings, YAG laser welding is non-contact, has a small heat affected layer,
It has low power consumption, is small in size, can be easily used for three-dimensional welding due to the use of optical fibers, and can divide a beam into multiple parts for simultaneous multipoint welding.
It is optimal because the automation is easy and the production cost is significantly reduced.

FIG. 2 shows a laser welding structure according to a second embodiment. FIG. 2A shows the bent leg 17 of the tab terminal 17a.
b, a concave portion 17p cut inward is formed, and the upper surface 17j of the bus bar 17 and the front end surface 17 of the bent leg portion 17b are formed.
k and the respective bonding interfaces E1, E between the bottom end face of the recess 17p
3 is obtained by irradiating a laser beam LB from an obliquely upward direction and welding. Thereby, the position of the welding a is dispersed at a plurality of positions, and the joining strength is stabilized.

FIG. 2 (B) shows a projection 17q projecting outward on the bent leg 17b of the tab terminal 17a.
Each bonding interface E between the upper surface 17j of the bus bar 17, the front end face 17k of the bent leg 17b, and the front end face of the projection 17q.
The laser beam LB was irradiated to each of E1 and E4 from an obliquely upward direction and welded. As a result, FIG.
Similarly to the above, the position of the weld a is dispersed at a plurality of locations, and the bonding strength is stabilized.

Incidentally, when the irradiation energy was the same, the bonding strength was 5.5 kgf in the comparative example of FIG. 4, but in the first embodiment of FIG. 1 or the second embodiment of FIG. It was 0.0 kgf, and the bonding strength was improved about five times.

FIG. 3 shows a laser welding structure according to a third embodiment. An upper through-hole 17r is formed at the joint interface E5 between the bus bar 17 and the inner end surfaces of the welding through-holes 17r and 17s formed coaxially with the bent legs 17b of the tab terminals 17a.
And welded by irradiating the laser beam LB from an obliquely upward direction. As a result, the bus bar 17 and the bent leg 17b of the tab terminal 17a start to be melted at the same time, so that the melting range and the melting depth are widened, and the bonding strength is stably increased.

When the irradiation energy is the same, the bonding strength is 5.5 kgf in the comparative example of FIG. 4, but is 20.2 kgf in the third embodiment of FIG. Double the joint strength.

[0038]

As is clear from the above description, in the laser welding structure of the present invention, welding is performed by irradiating a laser beam to the joining interface between the pattern portion of the bus bar and the bent leg portion of the tab terminal. Therefore, the bus bar and the tab terminal begin to be melted at the same time, so that if the irradiation energy for melting is the same, the melting range and the melting depth are widened, and the bonding strength is stably increased.

Further, the defect rate in the welding process is reduced,
Productivity is improved.

[Brief description of the drawings]

FIG. 1 is a laser welding structure according to a first embodiment of the present invention, in which (A) is a perspective view in which a tab terminal is laser-welded to a bus bar, and (B) and (C) are side sectional views, respectively.

FIG. 2 is a laser welding structure according to a second embodiment,
(A) and (B) are the perspective views which carried out the laser welding of the tab terminal to the bus bar, respectively.

FIG. 3 is a laser welding structure according to a third embodiment,
(A) is a perspective view in which a tab terminal is laser-welded to a bus bar,
(B) is a side sectional view.

FIG. 4 is a laser welding structure of a comparative example, in which (A) is a perspective view in which a tab terminal is laser-welded to a bus bar, and (B) is a side sectional view.

FIG. 5 is a perspective view of a tab terminal formed integrally with a relay terminal.

FIG. 6 is a perspective view of a conventional bus bar.

FIG. 7 is an exploded perspective view of a conventional bus bar processing and assembling procedure.

FIGS. 8A and 8B are perspective views of a conventional laser welding structure for a crimp terminal and the like.

[Explanation of symbols]

 9 Electrical connection box 17 Bus bar 17a Tab terminal 17b Bend leg 17c Relay terminal 17j Upper surface 17k Front end surface 17m, 17n Side end surface 17r, 17s Through hole 18 Insulating plate LB Laser beam a Welding E1-E5 Joining interface

Continuation of the front page (72) Inventor Takahiro Onizuka 1-7-10 Kikuzumi, Minami-ku, Nagoya City, Aichi Prefecture Inside Harness Research Institute, Inc. (72) Inventor Atsuhiko Fujii 1-7-10 Kikuzumi, Minami-ku, Nagoya City, Aichi Prefecture No. Harness Research Institute Co., Ltd. (72) Inventor Yoshifumi Saka 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi Pref.

Claims (5)

[Claims] 1. A structure in which an object to be welded is applied to the object to be welded, and the object to be welded is welded with a laser beam. A laser welding structure characterized by welding by irradiating a laser beam from a direction or a sideways direction. 2. The laser welding structure according to claim 1, wherein the joining interface is between an upper surface of the welded body and an end face of the welded body. 3. The laser welding structure according to claim 1, wherein the joining interface is between an end face of the welded body and an end face of the welded body. 4. The laser welding structure according to claim 1, wherein the joining interface is between each inner end face of the welding through hole formed in the welded body and the welded body. 5. The bus bar according to claim 1, wherein the welded body is a bus bar housed in an electric junction box, the welded body is a tab terminal, and a bent leg of the tab terminal is applied to a pattern portion of the bus bar. The joint interface between the tab portion and the bent leg portion of the tab terminal is welded by a laser beam.
The laser welding structure according to any one of the above.