KR20160047348A - Laser welding method - Google Patents

Laser welding method Download PDF

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Publication number
KR20160047348A
KR20160047348A KR1020140143666A KR20140143666A KR20160047348A KR 20160047348 A KR20160047348 A KR 20160047348A KR 1020140143666 A KR1020140143666 A KR 1020140143666A KR 20140143666 A KR20140143666 A KR 20140143666A KR 20160047348 A KR20160047348 A KR 20160047348A
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KR
South Korea
Prior art keywords
laser welding
welding
base material
welding method
present
Prior art date
Application number
KR1020140143666A
Other languages
Korean (ko)
Inventor
김경모
구본준
조경만
Original Assignee
주식회사 엘지화학
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to KR1020140143666A priority Critical patent/KR20160047348A/en
Publication of KR20160047348A publication Critical patent/KR20160047348A/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20—Bonding
    • B23K26/32—Bonding taking account of the properties of the material involved
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/60—Preliminary treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/08—Non-ferrous metals or alloys
    • B23K2103/10—Aluminium or alloys thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/08—Non-ferrous metals or alloys
    • B23K2103/12—Copper or alloys thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/18—Dissimilar materials

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method, and more particularly, to a laser welding method capable of improving defective products due to a decrease in tensile strength of a base material generated after welding.
The laser welding method according to the present invention includes a preparation step and a welding step of laser welding the base material along a welding line in which the cut-off portion exists.

Description

[0001] LASER WELDING METHOD [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method, and more particularly, to a laser welding method capable of improving defective products due to a decrease in tensile strength of a base material generated after welding.

The battery module is an intermediate assembly unit of a secondary battery pack used as a source of energy for a hybrid vehicle or an electric vehicle. The battery module basically comprises a battery cell, a cell cover, a module upper housing, and a module lower housing. To assemble the battery module, assemble the battery cell into the cell cover and insert it into the lower housing of the module.

At this time, there is a process of laser welding the lead of the cell to the bus bar. Laser welding using the laser welding device is necessary to connect the voltage of each cell in series to make the contact pressure . One exemplary configuration of the laser welding apparatus can be referred to in Patent Document 1 below.

In order to perform laser welding, the base material A and the base material W to be welded must be kept in close contact with each other. In the battery module, the lead of the cell and the bus bar of the module housing are welded, or the lead of the cell is mainly welded to one cell lead. The necessity of securing the welding quality by diversifying the laser welding method according to the base material composition .

The secondary battery battery pack to be used in an electric vehicle is required to have durability that can withstand the situation occurring during the running of the vehicle, such as vibration, and the environment. Therefore, the strength of the welding is a very important factor.

On the other hand, according to the conventional laser welding method, when the laser welding is performed in a state where three or more base materials are overlapped, there is a problem that the tensile strength of the base material located in the intermediate layer is lowered. The degradation of the tensile strength of the battery pack configuration after laser welding is a problem because it causes defective products and can seriously affect the safety of users.

Korean Patent Registration No. 10-0745295

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a laser welding method capable of improving defective products due to a decrease in tensile strength of a base material generated after laser welding.

The laser welding method according to the present invention includes a preparation process for preparing a base material to be welded and a welding process for laser welding the base material along a welding line in which a cut-off portion exists.

The laser welding method according to the present invention includes a preparing step and a welding step of laser welding the base material along the welding line where the cut-off portion exists, thereby improving the defect occurrence of the product due to the decrease in the tensile strength of the base material generated after welding .

1 is a perspective view showing a laser welding method in which tensile strength of a base material is lowered.
2 is a cross-sectional view taken along the line AA in Fig.
3 is a perspective view showing the laser welding method according to the first embodiment of the present invention.
4 is a perspective view showing a laser welding method according to a second embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the following Comparative Examples and Examples.

Laser welding method in which tensile strength is reduced ( Comparative Example )

1 is a perspective view showing a laser welding method in which tensile strength of a base material is lowered. 2 is a cross-sectional view taken along the line A-A in Fig.

Hereinafter, with reference to Figs. 1 and 2, the laser welding method in which the tensile force is lowered will be described first.

Referring to FIGS. 1 and 2, three base materials 131, 133, and 135 are overlapped and disposed for welding. In order to perform laser welding, an aluminum lead 131 (Al lead) is positioned on the uppermost layer irradiated with the laser 111, a copper lead 133 (Cu lead) is positioned on the middle layer, and a copper bus bar 135) (Cu Busbar) is located.

When the laser 111 emitted from the laser welding apparatus 110 is irradiated on the aluminum lead 131, the molten material of the aluminum lead 131 passes through the copper lead 133 and melts with the surface of the copper bus bar 135 , So that an inter-metallic compound 130 is formed.

At this time, a penetration portion 137 is formed in the copper lead 133 located in the intermediate layer by the intermetallic compound 130. In the penetration portion 137, the intermetallic compound 130 and the copper lead 133 The tensile strength of the copper lead 133 in the intermediate layer is lowered due to the presence of the penetrating portion 137 because the bonding force is relatively weak.

As shown in FIG. 2, when the tensile force F acts in both directions, there is a high possibility that the copper lead 133 is broken on both sides around the intermetallic compound 130.

Example  One

3 is a perspective view showing the laser welding method according to the first embodiment of the present invention.

Hereinafter, a laser welding method according to the first embodiment of the present invention will be described with reference to FIG.

The laser welding method according to the first embodiment of the present invention includes a preparation process and a welding process.

The preparation process is a process of preparing a base material to be laser welded. In the laser welding method according to the first embodiment of the present invention, three base materials 131, 133, and 135 are prepared. However, the scope of the present invention is not limited only to the case where three base metals are used, and the principle of the present invention can be applied to the case of welding a plurality of other base metals.

The three parent materials 131, 133 and 135 in Embodiment 1 are aluminum lead 131 (Al lead), copper lead 133 (Cu lead), and copper bus bar 135 (Cu Busbar). An aluminum lead 131 (Al lead) is located on the uppermost surface irradiated with the laser 111, a copper lead 133 (Cu lead) is formed in an intermediate layer, and a copper bus bar 135 (Cu Busbar) do. The three parent materials may be arranged such that at least a part of them overlaps each other.

If more than three preforms overlap, at least one of the preforms positioned between the preforms of the outermost layer may be made of a copper material.

In the laser welding method according to the first embodiment of the present invention, the welding step is a step of laser welding the base material along the welding line 150 using the laser welding apparatus 110, 133, 135 so that the portion 151 is present.

Since laser welding does not occur in the cut-off portion 151, the penetrating portion 137 formed by the intermetallic compound 130 described above is not formed at this portion. Accordingly, both ends of the copper lead 133 are connected to each other with respect to the welding line 150 in the disconnected portion 151. There is a part where the base material is connected to each other without penetrating the base material, so that the tensile force of the base material can be relatively strengthened.

Therefore, in the laser welding method according to the first embodiment of the present invention, even if the tensile force acts on both sides of the base material, the possibility that the copper lead 133 is broken to both sides is remarkably reduced. In this way, the laser welding method according to the first embodiment of the present invention can prevent the tensile strength of the base material from being lowered after the conventional laser welding. When a battery module having a tensile force is mounted in an electric vehicle, the durability of the battery can be ensured even in a vibration environment.

On the other hand, in the laser welding method according to the first embodiment of the present invention, a plurality of disconnected portions 151 may exist. That is, a plurality of disconnected portions 151 may exist on the same welding line 150. As the number of the cutoff portions 151 increases, the tensile strength of the base material can further increase.

The shape of the welding line 150 in which a plurality of the cutoff portions 151 are present can take various forms. If the welding line 150 has a regular broken line shape, the battery module can maintain a more stable and robust state.

Example  2

4 is a perspective view showing a laser welding method according to a second embodiment of the present invention.

The laser welding method according to the second embodiment of the present invention has a configuration similar to the laser welding method according to the first embodiment. However, the second embodiment differs from the first embodiment in that the welding line is different from the first embodiment.

For the sake of reference, the same (or significant) reference numerals are given to the same (or significant) parts as those of the above-described configuration, and a detailed description thereof will be omitted.

Hereinafter, a secondary battery according to a second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 4, in the laser welding method according to the second embodiment of the present invention, a plurality of welding lines 250 may be formed. In FIG. 4, two weld lines 250 are shown, but the number of weld lines 250 may be two or more.

The interlayer interlayers in the welding line 250 are bonded to each other without falling apart so that if the welding line 250 is formed longer or the number of the welding lines 250 is larger, the internal resistance of the battery module can be further reduced . When the internal resistance of the battery module is reduced, the energy efficiency is improved, and the performance of the product can be further improved.

While the present invention has been described in connection with certain exemplary embodiments and drawings, it is to be understood that the present invention is not limited thereto and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

110: Laser welding device
111: Laser
130: intermetallic compound
131: Aluminum lead
133: copper lead
135: Copper bus bar
137:
50, 150, 250: welding line
151, 251:

Claims (5)

A preparation step of preparing a base material to be welded; And
And a welding step of laser welding the base material along a welding line in which the cut-off portion exists. The method according to claim 1,
In the preparation step, three or more preforms are prepared, and at least a part of them is disposed so as to overlap with each other,
Wherein the base material positioned on the laser-irradiated side of the welding process is made of an aluminum material, and at least one of the base materials positioned between the base materials of the outermost layer is made of a copper material. The method according to claim 1,
Wherein a plurality of said cut-off portions are present on the same welding line. The method according to claim 1,
Wherein the welding line has a dashed line shape. The method according to claim 1,
Wherein a plurality of the welding lines are formed.
KR1020140143666A 2014-10-22 2014-10-22 Laser welding method KR20160047348A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020140143666A KR20160047348A (en) 2014-10-22 2014-10-22 Laser welding method

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10439191B2 (en) 2016-07-21 2019-10-08 Panasonic Intellectual Property Management Co., Ltd. Welded metal component and battery including the same
KR102407243B1 (en) * 2022-01-28 2022-06-13 덕양산업 주식회사 Laser-welding method for lead tabs of battery cells

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10439191B2 (en) 2016-07-21 2019-10-08 Panasonic Intellectual Property Management Co., Ltd. Welded metal component and battery including the same
EP3278919B1 (en) * 2016-07-21 2021-09-01 Panasonic Intellectual Property Management Co., Ltd. Welded metal component and battery including the same
KR102407243B1 (en) * 2022-01-28 2022-06-13 덕양산업 주식회사 Laser-welding method for lead tabs of battery cells

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