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CN-122007691-A - Nickel-plated copper-aluminum dissimilar metal water-adding welding method

CN122007691ACN 122007691 ACN122007691 ACN 122007691ACN-122007691-A

Abstract

The invention relates to the technical field of manufacturing of new energy automobile battery packs, and particularly discloses a water-adding welding method of nickel-plated copper-aluminum dissimilar metals, which comprises the following steps of S1, stacking and fixing a cleaned nickel-plated copper sheet and an aluminum sheet in a tool fixture provided with a flow passage; S2, supplying a water-based protective liquid containing a modified antioxidant auxiliary agent to a welding area through a runner, forming a gas-phase protective layer by utilizing in-situ vaporization of the water-based protective liquid, wherein the auxiliary agent is prepared by high-temperature condensation reaction of triethanolamine and boric acid, S3, starting an electrode to perform resistance hot-press welding on the welding area, continuously supplying the protective liquid in the welding process, controlling the flow and the temperature and the humidity of the protective liquid, and S4, continuously supplying the protective liquid or carrying out quenching treatment after the welding is finished. The invention utilizes the dual mechanism of physical isolation of water vapor and chemical reduction of auxiliary agent, effectively inhibits the yellowing of nickel plating layer due to high temperature oxidation, ensures that the welded joint keeps silvery white luster, and has excellent corrosion resistance and connection strength.

Inventors

  • YANG XUANPING
  • Jin Ziping
  • XU HUIJUN
  • XU YAZHU

Assignees

  • 福立旺精密机电（中国）股份有限公司

Dates

Publication Date
20260512
Application Date
20260318

Claims (9)

  1. 1. The water-adding welding method of the nickel-plated copper-aluminum dissimilar metal is characterized by comprising the following steps of: S1, providing a nickel-plated copper sheet and an aluminum sheet to be welded, and carrying out surface cleaning treatment on a region to be welded of the nickel-plated copper sheet and the aluminum sheet; s2, stacking and fixing the nickel-plated copper sheet and the aluminum sheet in a welding tool fixture, wherein the tool fixture is provided with a liquid diversion channel extending towards a welding area; S3, supplying a liquid protection medium to the welding area through the liquid diversion channel, wherein the liquid protection medium is vaporized in situ under the action of a welding thermal field to form a gas phase protection layer; S4, starting a welding heat source to heat and press the welding area, continuously supplying the liquid protection medium in the welding process, and controlling the flow of the liquid protection medium to be 0.05-0.10ml/s; S5, stopping heating after welding is finished, and continuously supplying the liquid protection medium or placing the welding piece in cooling liquid for cooling treatment; wherein the liquid protection medium is water-based solution, and the solvent is deionized water.
  2. 2. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein a modified antioxidation auxiliary agent is also dissolved in the liquid protection medium, and the preparation method of the modified antioxidation auxiliary agent comprises the following steps: P1, adding triethanolamine into a reaction vessel, heating to 60-70 ℃ and stirring at 300-500rpm; p2, adding boric acid into the triethanolamine in batches until the boric acid is completely dissolved to form transparent viscous liquid; p3. heating the reaction system to 110-120 ℃ and carrying out dehydration condensation reaction under the vacuum condition of-0.08 MPa to-0.09 MPa for 2-3 hours; P4. cooling to 80 ℃, adding benzotriazole, and stirring until the benzotriazole is completely dissolved; p5. adding deionized water to regulate the viscosity and cooling to room temperature to obtain the modified antioxidant auxiliary.
  3. 3. The water-added welding method for nickel-plated copper-aluminum dissimilar metals according to claim 2 is characterized in that the preparation raw materials of the modified antioxidation auxiliary agent comprise, by mass, 100 parts of triethanolamine, 40-50 parts of boric acid, 2-5 parts of benzotriazole and 20-30 parts of deionized water, and the volume ratio of the modified antioxidation auxiliary agent to the deionized water in the liquid protection medium is 1:10-1:20.
  4. 4. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein in step S3, the liquid protection medium is supplied by a method comprising: and (3) dripping liquid drops into the liquid diversion channel by using a guide pipe in a gravity dripping mode, wherein the diameter of the liquid drops is controlled to be smaller than 2mm, or atomizing the liquid protection medium into micro mist with the average particle diameter smaller than 50 mu m by using an ultrasonic atomizing device, and spraying the micro mist to the welding area by using a nozzle.
  5. 5. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein in step S3, the supply start time of the liquid protective medium is 0.5-1.0 seconds before the start of the welding heat source, and in step S4, the ambient relative humidity of the welding process is controlled to 20% -30%.
  6. 6. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein the welding heat source adopts a graphite electrode for resistance hot-press welding, the welding temperature is 600-650 ℃, the welding pressure is 0.3-0.5MPa, and the single-point welding time is 0.5-2.0 seconds.
  7. 7. The method for water-adding welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein the horizontal distance between the outlet of the liquid diversion channel and the center of the welding area is 10-20mm, the liquid diversion channel is in a slope shape, and the liquid protection medium is guided to flow to the bonding interface of the nickel-plated copper sheet and the aluminum sheet.
  8. 8. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein in step S5, the specific operation of the cooling treatment is that the welding piece is immersed in deionized water at normal temperature or running tap water immediately after the heating of the welding heat source is stopped until the temperature of the workpiece is lowered to room temperature.
  9. 9. The method for water-added welding of nickel-plated copper-aluminum dissimilar metals according to claim 1, wherein the thickness of the nickel-plated copper sheet is 0.5-2.0mm, the thickness of the aluminum sheet is 0.5-2.0mm, and the thickness of the nickel-plated layer is 2-10 μm.

Description

Nickel-plated copper-aluminum dissimilar metal water-adding welding method Technical Field The invention belongs to the technical field of manufacturing of new energy automobile battery packs, and particularly relates to a water-adding welding method for nickel-plated copper-aluminum dissimilar metals. Background In the manufacture of a battery pack for a new energy automobile, a nickel-plated copper sheet and an aluminum sheet need to be firmly welded together to complete the electrical connection between batteries. The surface of the copper sheet is plated with a layer of nickel mainly to improve the corrosion resistance of the copper sheet and enhance the compatibility of the copper sheet and an aluminum sheet during welding. When welding is performed by laser, ultrasonic, or the like, a high temperature is generated in the welding region. Such high temperatures can cause the surface of the nickel plating layer, which is originally silvery white, to change, and the color can change to yellow or tan. This change in color not only directly affects the appearance of the product, but may also mean that the original protective properties of the nickel plating layer are reduced. At present, it is common practice in the industry to blow inert gas such as argon gas to the welding area during welding in an attempt to isolate air to suppress such oxidative discoloration. However, this method is not effective for solving the yellowing problem of the nickel plating layer. The yellowing phenomenon of the nickel plating layer may be related to oxidation of nickel at high temperature, diffusion between nickel and copper, and optical interference effect caused by surface microstructure change. Therefore, a new process method is needed in the industry, the problem of yellowing of the appearance of the nickel plating layer in the welding process can be effectively solved while the quality of the welded joint is ensured, and the due metallic luster of the nickel plating layer is maintained. Disclosure of Invention The invention aims to provide a water-adding welding method for nickel-plated copper-aluminum dissimilar metals, which aims to solve the problems in the prior art. In order to achieve the above purpose, the invention provides a water-added welding method of nickel-plated copper-aluminum dissimilar metal, which comprises the following steps: S1, providing a nickel-plated copper sheet and an aluminum sheet to be welded, and carrying out surface cleaning treatment on a region to be welded of the nickel-plated copper sheet and the aluminum sheet; s2, stacking and fixing the nickel-plated copper sheet and the aluminum sheet in a welding tool fixture, wherein the tool fixture is provided with a liquid diversion channel extending towards a welding area; S3, supplying a liquid protection medium to the welding area through the liquid diversion channel, wherein the liquid protection medium is vaporized in situ under the action of a welding thermal field to form a gas phase protection layer; S4, starting a welding heat source to heat and press the welding area, continuously supplying the liquid protection medium in the welding process, and controlling the flow of the liquid protection medium to be 0.05-0.10ml/s; S5, stopping heating after welding is finished, and continuously supplying the liquid protection medium or placing the welding piece in cooling liquid for cooling treatment; wherein the liquid protection medium is water-based solution, and the solvent is deionized water. Preferably, the liquid protection medium is further dissolved with a modified antioxidant auxiliary agent, and the preparation method of the modified antioxidant auxiliary agent comprises the following steps: P1, adding triethanolamine into a reaction vessel, heating to 60-70 ℃ and stirring at 300-500rpm; p2, adding boric acid into the triethanolamine in batches until the boric acid is completely dissolved to form transparent viscous liquid; p3. heating the reaction system to 110-120 ℃ and carrying out dehydration condensation reaction under the vacuum condition of-0.08 MPa to-0.09 MPa for 2-3 hours; P4. cooling to 80 ℃, adding benzotriazole, and stirring until the benzotriazole is completely dissolved; p5. adding deionized water to regulate the viscosity and cooling to room temperature to obtain the modified antioxidant auxiliary. Preferably, the preparation raw materials of the modified antioxidant auxiliary comprise, by mass, 100 parts of triethanolamine, 40-50 parts of boric acid, 2-5 parts of benzotriazole and 20-30 parts of deionized water, wherein the volume ratio of the modified antioxidant auxiliary to the deionized water in the liquid protective medium is 1:10-1:20. Preferably, in step S3, the supplying manner of the liquid protection medium includes: and (3) dripping liquid drops into the liquid diversion channel by using a guide pipe in a gravity dripping mode, wherein the diameter of the liquid drops is controlled to be smaller than 2mm