CN113146037B - Laser high-speed spiral spot welding method for aluminum/copper dissimilar material sheet - Google Patents

Laser high-speed spiral spot welding method for aluminum/copper dissimilar material sheet Download PDF

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CN113146037B
CN113146037B CN202110413004.2A CN202110413004A CN113146037B CN 113146037 B CN113146037 B CN 113146037B CN 202110413004 A CN202110413004 A CN 202110413004A CN 113146037 B CN113146037 B CN 113146037B
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welding
aluminum
copper
laser
plate
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CN113146037A (en
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黄婷
杜伟哲
肖荣诗
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Beijing University of Technology
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Beijing University of Technology
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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
    • B23K26/21—Bonding by welding
    • 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
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a laser high-speed spiral spot welding method for aluminum/copper dissimilar material thin plates, which comprises the steps of firstly electroplating a layer of metal nickel with the thickness of 1-3 mu m on the surface of a copper plate so as to reduce the formation of aluminum copper intermetallic compounds in the welding process and improve the joint performance. And then assembling in a lap joint mode of an aluminum plate at the upper part and a copper plate at the lower part, and finally performing spiral spot welding by adopting a high-beam quality laser and a scanning galvanometer system. The invention adopts the joint form of combining fusion welding and fusion brazing, generates partial fusion on a scanning path, forms diffusion connection at the non-overlapped part, reduces the generation of defects in welding spots, improves the joint performance and improves the welding efficiency.

Description

Laser high-speed spiral spot welding method for aluminum/copper dissimilar material sheet
Technical Field
The invention relates to a laser welding method, in particular to a laser welding method for a dissimilar material sheet, and belongs to the technical field of material connection.
Background
Industrial blue book jointly issued by units such as China society academy of sciences and the like: the China industry competitiveness report (2020) indicates that China is currently the country with the largest amount of new energy automobiles and establishes the charging facilities with the largest universal rule. According to the prediction, the total production and marketing scale of the Chinese new energy automobile can reach tens of millions during the period of fourteen and fifty. The data show that the production and marketing of the new energy automobile are respectively completed by 16.7 ten thousand and 16 ten thousand in the month 10 of 2020, and the same ratio is respectively increased by 69.7 percent and 104.5 percent.
The lithium ion battery has the characteristics of high energy ratio, long service life, high rated voltage, high power bearing capacity, light weight, environmental protection and the like, and can realize the technical indexes of stability, convenience, light weight and the like, so that the power source adopted by the current mainstream new energy automobile is a lithium ion battery (a lithium iron phosphate battery and a ternary lithium battery).
The lithium ion battery adopted by the new energy automobile power supply is a battery pack, the new energy battery pack is formed by connecting a large number of battery cells, and for a lithium battery cell with larger energy density, the lugs of the lithium battery cell are usually aluminum and copper. Examples of BUSBAR materials used for connecting the electrodes include aluminum, copper, nickel-plated copper, and the like. The connection of the battery tab, the connection of the tab and BUSBAR are all made of aluminum/copper dissimilar materials. Because the physical parameters of the materials of the aluminum and copper are greatly different, and AlCu and Al are extremely easy to be generated 2 Cu、Al 3 Cu 4 、Al 4 Cu 9 Iso-aluminum copper intermetallic compounds, the aluminum copper intermetallic compoundsThe compound has the characteristics of hardness, brittleness, large resistance and the like, and has obvious influence on the mechanical and electrical properties of the welded joint. There is no effective method for welding the aluminum/copper dissimilar materials of the thin plate at home and abroad.
The existing laser melting welding and laser melting brazing adopt the melting welding and brazing principles respectively. During fusion welding, intermetallic compounds are inevitably generated in the weld joint. The joint strength decreases with an increase in intermetallic compound, and the decrease in the static load strength of the joint is particularly serious when the intermetallic compound layer is in a continuous dense state. And the scanning path shown in the figure 1 is generally adopted to expand the area of the welding seam connecting surface, so that the process is extremely easy to generate air hole defects shown in the longitudinal section of the welding seam in the figure 2, and the joint performance is influenced. The laser welding and brazing efficiency is low, the process window is narrow, and the joint strength is not high. The high energy density of nanosecond laser causes severe spattering welding defects in the welding process, and as shown in fig. 3, the spiral can further increase the spattering generation, greatly influence the joint performance, and also cause the problems of narrow process window and the like.
Disclosure of Invention
The invention aims to provide a method for welding aluminum/copper dissimilar material thin plates, so as to solve the problems of performance and welding efficiency of the aluminum/copper dissimilar material thin plate welding joint in the prior art. .
The technical scheme of the invention is as follows.
The invention provides a laser high-speed spiral spot welding method for aluminum/copper dissimilar material thin plates, which comprises the following steps of:
step S1, electroplating a layer of metal nickel on the surface of a copper plate, and cleaning the surfaces of the parts to be welded of the aluminum plate and the nickel-plated copper plate;
s2, assembling in a lap joint mode of aluminum upper part and copper lower part;
and S3, performing laser spiral spot welding by adopting a scanning galvanometer according to a spiral line scanning mode.
Preferably, the thickness of the metallic nickel in the step S1 is 1 to 3 μm.
Preferably, the laser power of the laser welding in the step S3 is 200-1000W.
Preferably, the focused spot diameter of the laser welding in the step S3 is 20-100 μm.
Preferably, the laser welding in the step S3 has a power density of (1-5). Times.10 7 W/cm 2 。
Preferably, the scanning speed of the laser welding in the step S3 is 100-1000mm/S.
Preferably, the pitch of the laser welding in the step S3 is 0.8-1.5 times of the spot diameter.
Preferably, the thickness of the aluminum plate is 100-500 μm.
Preferably, in the step S3, appropriate welding process parameters are selected according to the thickness of the aluminum plate, so that the penetration depth on the copper plate is controlled below 40 μm.
Preferably, the penetration on the copper plate in the step S3 is controlled to be 20 μm or less.
According to the invention, a layer of metal nickel with the thickness of 1-3 mu m is electroplated on the surface of the copper plate, a base mode laser and a scanning galvanometer system are used for high-speed scanning, and the melting amount of copper is accurately controlled by means of accurate and extremely low heat input, so that the formation of intermetallic compounds between aluminum and copper in the welding process is reduced, the joint performance is ensured, and high-efficiency welding is realized.
And a layer of metal nickel with the thickness of 1-3 mu m is electroplated on the surface of the copper plate, so that infinite solid solution can be formed by nickel and copper, and the formation of aluminum-copper intermetallic compounds can be effectively reduced. The high-speed scanning is performed by using the fundamental mode fiber laser and the scanning galvanometer system, and the splashing and burning caused by the nanosecond laser can be effectively avoided by providing an adjusting process, and the melting amount of copper is accurately controlled by means of accurate and extremely low heat input. The invention adopts the joint form of combining fusion welding and fusion brazing, generates partial fusion on a scanning path, forms diffusion connection at the non-overlapped part, reduces the generation of defects in welding spots, improves the joint performance and improves the welding efficiency.
Drawings
FIG. 1 is a schematic diagram of a prior art laser welding scan path;
FIG. 2 is a longitudinal cross-sectional view of the weld obtained by the laser welding scan of FIG. 1;
FIG. 3 is a schematic cross-sectional view of a prior art nanosecond laser spiral spot welding surface;
FIG. 4 is a schematic view of a laser welding scan path according to the present invention;
FIG. 5 is a surface view of a weld obtained by the laser welding of FIG. 4;
fig. 6 is a cross-sectional view of a weld obtained by the laser welding in fig. 4.
Detailed Description
The term "spiral spot welding" as used in the present invention refers to a welding method in which a base material is melted in a spiral scanning manner to form a weld spot.
The term "intermetallic compound" as used herein refers to a compound composed of two or more metal or metalloid components in proportion having metal basic properties and a long-range ordered crystal structure different from the components thereof.
The term "EDS scan analysis" as used herein refers to the qualitative and semi-quantitative analysis of a sample for elements using an X-ray energy spectrum analyzer.
The technical scheme of the invention is specifically described below with reference to specific embodiments.
The technical purpose of the invention is to realize the welding of the aluminum plate with the thickness of 100-500 mu m and copper plates with different thicknesses.
Firstly, a layer of metal nickel with the thickness of 1-3 mu m is electroplated on the surface of the copper plate, so that the formation of aluminum copper intermetallic compounds in the welding process is reduced, and the joint performance is improved.
Then, the aluminum plate is assembled in a lap joint mode with the upper copper plate and the lower copper plate.
And finally, performing spiral spot welding by adopting a high-beam quality laser and a scanning galvanometer system.
The diameter of the focusing spot of the laser beam is 20-100 mu m, and the power density is 10 7 W/cm 2 And forming deep-melting small holes on the aluminum plate in the welding process. In a preferred embodiment
In the welding process, the laser beam is scanned at a high speed according to a spiral path shown in fig. 4, and proper technological parameters are selected to control the penetration of the copper side below 40 mu m.
Those skilled in the art will appreciate that although the helical path is shown in fig. 4 as a left-handed helix, the invention is not so limited. Any two-dimensional spiral suitable for use as a laser scan path may be suitable for use in the present invention, such as a left-handed or right-handed constant velocity spiral, an equiangular spiral, etc.
According to the invention, a layer of metal nickel with the thickness of 1-3 mu m is electroplated on the surface of the copper plate, a base mode laser and a scanning galvanometer system are used for high-speed scanning, and the melting amount of copper is accurately controlled by means of accurate and extremely low heat input, so that the formation of intermetallic compounds between aluminum and copper in the welding process is reduced, the joint performance is ensured, and high-efficiency welding is realized.
And a layer of metal nickel with the thickness of 1-3 mu m is electroplated on the surface of the copper plate, so that infinite solid solution can be formed by nickel and copper, and the formation of aluminum-copper intermetallic compounds can be effectively reduced. The high-speed scanning is performed by using the fundamental mode fiber laser and the scanning galvanometer system, and the splashing and burning caused by the nanosecond laser can be effectively avoided by providing an adjusting process, and the melting amount of copper is accurately controlled by means of accurate and extremely low heat input. The invention adopts the joint form of combining fusion welding and fusion brazing, generates partial fusion on a scanning path, forms diffusion connection at the non-overlapped part, reduces the generation of defects in welding spots, improves the joint performance and improves the welding efficiency.
Example 1
The present example provides a method of welding together an aluminum plate having a thickness of 100-500 μm and a copper plate using the following specific technical scheme.
Electroplating a layer of metal nickel with the thickness of 1-3 mu m on the surface of the copper plate, and cleaning the surfaces of the parts to be welded of the aluminum plate and the nickel-plated copper plate.
And assembling in a lap joint mode of aluminum upper part and copper lower part.
And (4) performing laser spiral spot welding in a spiral line scanning mode shown in fig. 4 by adopting a scanning galvanometer.
In the step of laser welding, proper welding parameters are selected according to the thickness of the aluminum plate. In a preferred embodiment, the welding parameters range as follows:
laser power: 200-1000W;
focused spot diameter: 20-100 μm;
power density: (1-5). Times.10 7 W/cm 2 ；
Scanning speed: 100-1000mm/s;
pitch: 0.8-1.5 times of the diameter of the light spot.
Example 2
The present example provides a method of welding together an aluminum plate having a thickness of 200 μm and a copper plate. The specific technical scheme adopted in this embodiment is as follows.
Electroplating a layer of metal nickel with the thickness of 2 mu m on the surface of the copper plate, and cleaning the surfaces of the parts to be welded of the aluminum plate and the nickel-plated copper plate.
And assembling in a lap joint mode of aluminum upper part and copper lower part.
And (4) performing laser spiral spot welding in a spiral line scanning mode shown in fig. 4 by adopting a scanning galvanometer.
In the step of laser welding, proper welding parameters are selected according to the thickness of the aluminum plate, and the specific welding parameters range is as follows:
laser power: 300W
Spot diameter: 55 mu m
Scanning speed: 500mm/s
Pitch: 80 μm
Welding spot diameter: 0.8mm
The surface view of the weld spot obtained by the laser welding according to the method of the present embodiment is shown in fig. 5, and the cross-sectional view of the weld spot is shown in fig. 6. It can be seen that the present embodiment obtains a joint form in which fusion welding and fusion welding are combined, partial fusion is generated on the scanning path, diffusion connection is formed at the non-overlapped portion, the occurrence of defects in the welding spot is reduced, the joint performance is improved, and the welding efficiency is improved.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art will appreciate that many modifications, variations, substitutions, and equivalents are possible in light of the above teachings without departing from the scope of the invention as defined by the appended claims.

Claims (3)

1. A laser high-speed spiral spot welding method for aluminum/copper dissimilar material thin plates comprises the following steps:
step S1, electroplating a layer of metal nickel on the surface of a copper plate, and cleaning the surfaces of the parts to be welded of the aluminum plate and the nickel-plated copper plate;
s2, assembling in a lap joint mode of aluminum upper part and copper lower part;
s3, performing laser spiral spot welding by adopting a scanning galvanometer according to a spiral line scanning mode to obtain a welding spot joint form combining fusion welding and fusion brazing;
the laser power of the laser welding in the step S3 is 200-1000W;
the diameter of the focusing light spot of the laser welding in the step S3 is 20-100 mu m;
the power density of the laser welding in the step S3 is (1-5) multiplied by 10 7 W/cm 2 Thereby forming deep-melting small holes on the aluminum plate in the welding process;
the scanning speed of the laser welding in the step S3 is 100-1000mm/S;
the thickness of the aluminum plate is 100-500 mu m;
step S3, selecting proper welding process parameters according to the thickness of the aluminum plate, and controlling the penetration depth on the copper plate to be below 40 mu m;
the spiral line is a left-handed or right-handed two-dimensional spiral line;
the pitch of the laser welding in the step S3 is 0.8-1.5 times of the diameter of the light spot, so that partial melting is generated on the scanning path, and diffusion connection is formed at the non-overlapped part.
2. The method for laser high-speed spiral spot welding of aluminum/copper dissimilar material thin plate according to claim 1, wherein the thickness of the metallic nickel in the step S1 is 1-3 μm.
3. The method for laser high-speed spiral spot welding of aluminum/copper dissimilar material thin plate according to claim 1, wherein the penetration depth on the copper plate in the step S3 is controlled below 20 μm.
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CN113770532A (en) * 2021-10-09 2021-12-10 哈尔滨工业大学 Method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel
CN114346429A (en) * 2021-12-27 2022-04-15 深圳泰德激光技术股份有限公司 Laser welding method for thin materials
CN115156651A (en) * 2022-04-29 2022-10-11 深圳市汇北川电子技术有限公司 Laser welding method for copper bar of electronic device
CN114986001B (en) * 2022-06-10 2024-03-29 北京工业大学 Method for welding dissimilar metals of ultrathin plate
CN115464266A (en) * 2022-09-27 2022-12-13 上海工程技术大学 Laser double-beam double-helix spot welding method

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DE102004009651B4 (en) * 2004-02-27 2008-10-09 BLZ Bayerisches Laserzentrum Gemeinnützige Forschungsgesellschaft mbH Process for the welding of dissimilar metallic joining partners, in particular aluminum-copper joints
WO2017190042A1 (en) * 2016-04-29 2017-11-02 Nuburu, Inc Visible laser welding of electronic packaging, automotive electrics, battery and other components
CN110253146B (en) * 2019-07-03 2021-08-27 湖南科技大学 High-strength copper-aluminum dissimilar material double-helix welding process
CN112355420A (en) * 2020-10-14 2021-02-12 北京工业大学 Optical fiber laser aluminum-copper butt fusion brazing method based on welding wire deep melting behavior
CN112439994A (en) * 2020-11-17 2021-03-05 上海思客琦自动化工程有限公司 Laser welding process for dissimilar metal connecting material at lithium battery tab part
CN112439993A (en) * 2020-11-17 2021-03-05 上海思客琦自动化工程有限公司 Single-mode laser welding process for nickel-plated copper and 6-series aluminum alloy

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