Laser welding method for new energy automobile aluminum alloy water-cooled plate integrated battery shell

Abstract

A laser welding method of an aluminum alloy water-cooled plate integrated battery shell for new energy vehicles belongs to the technical field of aluminum alloy laser welding. The laser welding method of the aluminum alloy water-cooled plate integrated battery shell for new energy vehicles comprises the following steps: S1, welding preparation: polishing, wiping and fixing the workpiece to be welded; setting the welding parameters: the welding power is 3800-4000 W, the welding speed is 2-3 m / min, the spot diameter is 0.4-0.5 mm, the defocusing amount is -3-3 mm; the laser pulse duration is 28-32 ms, the laser pulse frequency is 30-34 Hz, the preheating and holding waveform is selected; the wire feeding speed is 3-3.4 m / min; pre-welding demonstration: pre-welding demonstration is performed on the workpiece to be welded; welding workpiece: the workpiece to be welded is welded by using the laser pulse wire filling welding method. The laser welding method of the aluminum alloy water-cooled plate integrated battery shell for new energy vehicles has simple operation steps, high practicability, low requirement for tool precision, optimized laser welding process parameters, and can ensure good weld performance and good appearance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser welding of aluminum alloy, and particularly relates to a laser welding method of an aluminum alloy water-cooled plate integrated battery shell for a new energy vehicle. BACKGROUND

[0002] Laser welding is a method of using a focused laser beam as an energy source to bombard the welding part to generate heat for welding. Laser welding has always been an essential process in the manufacturing process of automobile batteries. Laser welding technology is widely used from stainless steel shells to aluminum alloy shells. Compared with traditional arc welding, laser welding has the advantages of high energy density, high welding efficiency, small heat input and good accessibility, and is a high-quality and efficient welding method. Laser welding can be divided into continuous laser welding and pulse laser welding.

[0003] Due to the high reflectivity of aluminum alloy and the strong evaporation of low-boiling alloy elements, especially the burning loss of low-boiling strengthening alloy elements is very serious, which causes the fluctuation of deep penetration keyhole, resulting in poor stability in the process of laser welding of aluminum alloy, and defects such as pores and cracks in the weld, and it is difficult to obtain a good weld. The most common problem is porosity, which can seriously damage the density of the weld metal, weaken the effective cross-sectional area of the weld, and greatly reduce the mechanical properties of the weld.

[0004] At present, the pure laser welding method mainly welds through the track determined by the welding fixture. The water-cooled plate integrated battery shell has certain requirements for air tightness, the joint mode is a lap joint structure, so there is a fitting gap in the assembly process, so the positioning accuracy of the fixture is required to be high, and the process parameters are required to be harsh. Due to the fact that the weld is not in the same plane, the difficulty of selecting welding process parameters is increased, and when editing the welding track, the transformation of the laser beam angle and the track of the light speed are considered, which leads to the problems of poor air tightness, pores, welding deviation, craters, welding through and other quality defects after laser welding. SUMMARY

[0005] In order to solve the defects generated in the process of laser welding in the prior art, the present application provides a laser welding method of an aluminum alloy water-cooled plate integrated battery shell for a new energy vehicle, which has the advantages of simple operation, strong practicability, low requirement for fixture precision, optimized laser welding process parameters, and good weld performance and beautiful forming.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A laser welding method of an aluminum alloy water-cooled plate integrated battery shell for a new energy vehicle, comprising the following steps:

[0008] S1, preparation before welding:

[0009] polishing, wiping and fixing the workpieces to be welded;

[0010] S2, setting welding parameters:

[0011] The laser welding parameters are set as follows: welding power is 3800-4000 W, welding speed is 2-3 m / min, spot diameter is 0.4-0.5 mm, and defocusing amount is -3-3 mm;

[0012] The pulse parameters are set as follows: laser pulse duration is 28-32 ms, laser pulse frequency is 30-34 Hz, and preheating and holding waveform is selected;

[0013] The wire feeding parameters are set as follows: wire feeding speed is 3-3.4 m / min;

[0014] S3, teaching before welding:

[0015] The workpieces to be welded are taught before welding;

[0016] S4, welding workpieces:

[0017] According to the welding parameters in step S2, the workpieces to be welded are welded by using the laser pulse wire filling welding method.

[0018] Further, the polishing, wiping and fixing of the workpieces to be welded specifically include: polishing the workpieces to be welded, removing the oxidation layer and oil stains around the welding area until the metal body is exposed; wiping clean with volatile organic solvents; and placing the workpieces to be welded on a special tooling platform for fixed clamping;

[0019] Further, when welding, high-purity argon with a concentration not less than 99.99% is used for front protection, the front side blowing gas flow is 28-32 L / min, and the jet direction of the protective gas forms a 30° angle with the plane of the welded part.

[0020] Further, when welding, the angle formed by the laser beam and the welding surface is 90 degrees.

[0021] Further, the laser welding method of the aluminum alloy water-cooled plate integrated battery shell for new energy vehicles further comprises step S5, post-welding detection and analysis:

[0022] After welding, the aluminum alloy water-cooled plate integrated battery shell is inflated to 355 KPa±5 KPa gas pressure to fill the water-cooled pipe, and the leakage rate in the box is measured for 60 s after stable pressure, and the absolute value of pressure drop is less than 161 Pa for air tightness detection.

[0023] The beneficial effects of the present application are:

[0024] 1) The laser welding method of the present application has simple operation steps, strong practicability, low requirement for tool precision, optimized laser welding process parameters, good weld performance, good appearance, and meets customer needs;

[0025] 2) The laser pulse wire filling welding method combining laser welding, laser wire filling welding and laser pulse is used to obtain a weld with good appearance, no cracks, pores and other defects on the visual surface, no welding through, welding bleeding, heat marks and other defects on the back, increased fault tolerance in the wire filling process, and low requirement for tool precision compared with laser welding;

[0026] 3) The laser welding method of the present application reduces the post-repair rate, reduces the working hours, saves the production cost to a certain extent, and solves the technical problems of traditional laser welding technology, such as strict requirements for tool and workpiece, workpiece welding surface process design not in the same plane, welding with angle slope, and poor workpiece airtightness in the welding process.

[0027] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of the laser welding method of the integrated battery shell of the aluminum alloy water cooling plate for new energy vehicles provided by the embodiment of the present application;

[0029] Figure 2 is a schematic diagram of the fillet weld of the lap joint;

[0030] Figure 3 is a schematic diagram of the single-sided welding structure and weld position of the water cooling plate;

[0031] Figure 4 is a schematic diagram of the integrated battery shell of the water cooling plate;

[0032] Figure 5 is a preheating and holding waveform diagram provided by the embodiment of the present application.

[0033] The reference signs in the drawings of the specification include:

[0034] 1-5 is an aluminum alloy, 2 is a weld, 3-6 is an aluminum alloy, 4 is a box, 5 is a sealing plate, 6 is a water inlet, 7 is a water outlet, 8 is a preheating stage, 9 is a rising stage, 10 is a falling stage, and 11 is a holding stage. DETAILED DESCRIPTION

[0035] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described in the description of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application.

[0036] In the description of the present application, unless otherwise specified and limited, it is necessary to explain that the terms "mounting", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, it can be the communication inside two elements, it can be direct connection or indirect connection through intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0037] In order to solve the problems existing in the prior art, such as Figures 1 to 2 As shown in the drawings, the present application provides a laser welding method of an aluminum alloy water-cooled plate integrated battery shell for a new energy vehicle, comprising the following steps:

[0038] S1, welding preparation:

[0039] The workpiece to be welded is polished, wiped and fixed: the workpiece to be welded is polished to remove the oxide layer and oil stains around the welding area until the metal body is exposed; volatile organic solvents are used for cleaning; the workpiece to be welded is placed on a special tool platform for clamping;

[0040] Specifically, in the field of new energy vehicles, dissimilar alloy welding is mostly 5 series aluminum alloy 1 and 6 series aluminum alloy 3 welding, that is, 5XXX aluminum alloy and 6XXX aluminum alloy, this embodiment uses 1.5mm thick 6063-T6 aluminum alloy and 1.2mm thick 5182-O aluminum alloy dissimilar alloy for welding, the joint form adopts the lap joint fillet weld 2 mode of thin plate on the upper, and ER5087φ1.2 is selected for welding wire. The workpiece to be welded is polished to remove the oxide layer and oil stains around the welding area until the bright white metal body is exposed, then volatile organic solvents are used for cleaning, and then the workpiece is placed on a special tool platform for clamping.

[0041] In this embodiment, as shown in Figure 3 and Figure 4 The aluminum alloy water-cooled plate integrated battery shell includes a box body 4 for carrying batteries and a sealing plate 5 arranged on the box body 4, and the sealing plate 5 is a cover plate buckled on the box body 4. The sealing plate 5 is provided with a water-cooled pipe, the water inlet 6 of the water-cooled pipe flows in cooling water, the water outlet 7 of the water-cooled pipe flows out cooling water, the water inlet 6 and the water outlet 7 play a role of cooling water circulation, and are used for cooling the batteries carried in the box body 4.

[0042] S2, setting welding parameters:

[0043] Set the laser welding parameters: welding power is 3800-4000W, welding speed is 2-3m / min, spot diameter is 0.4-0.5mm, and defocusing amount is -3-3mm;

[0044] Set the pulse parameters: the laser pulse duration is 28-32ms, the laser pulse frequency is 30-34Hz, and the preheating and holding waveform is selected;

[0045] Set the wire feeding parameters: the wire feeding speed is 3-3.4m / min;

[0046] In the laser welding process, the heat transfer mode is extremely important for the formation of the welding pool and the temperature distribution, and the shaped pulse changes the energy distribution of the laser pulse, and different pulse shapes mean different energy delivery modes. Figure 5 As shown in the figure, the preheating and holding waveform adopted by the application includes a preheating stage 8, a rising stage 9, a falling stage 10 and a holding stage 11, the preheating and holding waveform is initially flat, the molten metal is melted through the heat conduction mechanism to reduce the reflection loss of the material and rapidly heat the material, then the power is suddenly increased to form a sharp pulse, during the action of the sharp pulse, the energy transmission is no longer dependent on the wavelength of the laser and the surface state of the material, but a keyhole plasma is formed to increase the energy absorption and increase the penetration depth, and then the energy is slowly reduced to control the cooling speed of the metal solidification process, reduce internal stress, and inhibit the formation of cracks and pores.

[0047] S3, pre-welding teaching:

[0048] The pre-welding teaching is performed on the workpiece to be welded;

[0049] Specifically, the pre-welding teaching is performed on the workpiece, because the weld 2 of such a workpiece is not in the same plane and has a slope angle, the laser pulse wire filling welding is selected for the welding process, and the laser pulse wire filling welding is realized by using a laser welding device.

[0050] S4, welding workpiece:

[0051] According to the welding parameters in step S2, the laser pulse wire filling welding method is used to weld the workpiece to be welded;

[0052] During welding, high-purity argon with a concentration of not less than 99.99% is used for front protection, the front side blowing gas flow is 28-32L / min, the jet direction of the protective gas forms a 30° angle with the plane of the welded part; during welding, the angle formed by the laser beam and the welding surface is 90 degrees.

[0053] The laser welding method of the aluminum alloy water-cooled plate integrated battery shell for new energy vehicles further includes the step S5, post-welding detection and analysis:

[0054] After welding, the water-cooled plate integrated battery shell of the aluminum alloy is filled with water-cooled pipes using 355 KPa ± 5 KPa air pressure, and the leakage rate of the box 4 is measured after the pressure is stabilized for 60 s, and the absolute value of the pressure drop is less than 161 Pa to detect the air tightness.

[0055] As an efficient advanced connection method, laser welding has been widely used in the field of new energy vehicles. Using pulse laser as the welding heat source, the heat input during the welding process can be accurately controlled, which is beneficial to control the deformation. The light output mode of laser can be divided into continuous and pulse, and the pulse width not only affects the penetration and width of the weld 2, but also affects the distribution of pores in the weld 2. Under the condition of certain heat input, the penetration of the weld 2 fluctuates less, and different pulse widths change the time ratio of pulse laser value and base value, and when the pulse width is large, it can ensure that there is enough energy to maintain the small hole of laser welding, which is helpful to control the pores. When the single pulse energy is constant, selecting a larger pulse is helpful to control the number of pores in the weld 2.

[0056] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A laser welding method for an aluminum alloy water-cooled plate integrated battery case for a new energy vehicle, characterized by, Comprise the following steps: S1, before welding preparation: Polish, wipe and fix the workpiece to be welded; S2, set the welding parameters: Set the laser welding parameters: welding power is 3800~4000W, welding speed is 2~3m / min, spot diameter is 0.4~0.5mm, defocusing amount is-3~3mm; Set the pulse parameters: laser pulse duration is 28~32ms, laser pulse frequency is 30~34Hz, select preheating holding waveform, including preheating stage, rising stage, falling stage and holding stage; Set the wire feeding parameters: wire feeding speed is 3~3.4m / min; S3, before welding teaching: Before welding teaching to the workpiece to be welded; Because the weld of such workpiece is not in the same plane, there is a slope angle, the welding process selects laser pulse wire filling welding; S4, weld the workpiece: According to the welding parameters in step S2, the workpiece to be welded is welded by laser pulse wire filling welding method; When welding, use high-purity argon with a concentration not less than 99.99% for front protection, the front side blowing gas flow is 28~32L / min, the jet direction of the protective gas is 30°angle with the welded part plane; S5, after welding detection and analysis: After welding, the aluminum alloy water-cooled plate integrated battery shell is filled with water-cooled pipes with 355KPa±5KPa gas pressure, and the leakage rate in the tank is measured after stable pressure for 60s, and the pressure drop absolute value is less than 161Pa for air tightness detection.

2. The laser welding method of the aluminum alloy water-cooled plate integrated battery case for new energy vehicles according to claim 1, characterized in that, The polishing, wiping and fixing of the workpiece to be welded specifically includes: polishing the workpiece to be welded, removing the oxidation layer and oil stains around the welding area until the metal body is exposed; Wipe clean with volatile organic solvents; Place the workpiece to be welded on the special tool platform for fixed clamping.

3. The laser welding method of the aluminum alloy water-cooled plate integrated battery case for new energy vehicles according to claim 1, characterized in that, When welding, the included angle between the laser beam and the welding surface is 90 degrees.

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