Laser welding method for liquid cooling plate shell of new energy automobile

Abstract

The invention provides a laser welding method for a liquid cooling plate shell of a new energy automobile. The laser welding method comprises the steps that a welding assembly tool is positioned; fixing the liquid cooling plate profile and the sealing plate on a welding assembly tool; a welding system is set, welding parameters and welding waveforms are determined, and the welding waveforms comprise the pulse laser welding pulse waveform and the laser welding pulse waveform at the light receiving position; adjusting a laser head angle, a welding gun angle and a shielding gas copper nozzle angle; and the liquid cooling plate profile and the sealing plate are welded through pulse laser of the pulse laser welding pulse waveform to obtain a welding seam, the laser receiving position is stopped at the tail end of the welding seam, the laser welding pulse waveform at the laser receiving position is used for adjusting the tail end of the welding seam, a liquid cooling plate shell is obtained, and welding is stopped. The problem of welding deformation can be effectively avoided, the welded liquid cooling plate is pressed to be qualified, the situation of air leakage is avoided, and the product percent of pass is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of metal processing, in particular to the technical field of metal welding, and specifically discloses a laser welding method for a liquid cooling plate shell of a new energy vehicle. Background Art

[0002] Lightweighting of automobiles and advanced welding technology have become hot research topics in the current automobile manufacturing industry. Under the condition of ensuring that the strength and rigidity meet the safety of the body structure, lightweight materials are sought to replace traditional steel plates. In order to reduce the weight of the body, aluminum alloy materials have become one of the indispensable alternative materials in the body, such as extruded profiles, castings, stamped sheet metal parts, etc. Laser welding has the advantages of low welding heat input, high energy density, narrow weld, small heat-affected zone, good joint performance, and high welding efficiency. It is currently widely used in the welding structure of aluminum alloy products of new energy vehicles. As an indispensable structure in new energy electric vehicles, the automotive liquid cooling plate has strict requirements on sealing. At present, the main material is a lightweight aluminum alloy, and the welding method is continuous laser wire welding. However, the continuous laser welding output energy is stable and continuous, and the heat input is large. It is not easy to control the welding deformation for thin plates.

[0003] The liquid cooling plate of the battery box of new energy vehicles is welded and formed by 6 series aluminum alloy extruded profiles and 5 series aluminum alloy stamped sheet metal parts through advanced laser welding technology. In order to ensure the consistency of welding, the precision of the welding fixture is high, and the sealing and overall strength and rigidity must be ensured. Manual pressing is adopted when the sealing plate and the main body of the liquid cooling plate profile are assembled and pressed. Most of the fitting and pressing of the extruded profile and the sheet metal parts are also carried out by manual clamps, and the clamping arm with bosses is pressed at multiple points. The manual assembly and manual clamping will lead to uneven pressing force, large welding stress, and defects after welding. In addition, since the welds at the boss position are not in the same horizontal plane, there will be high and low platform weld trajectories. When the tooling fixture is not robust and the incoming workpiece is inconsistent, it is very easy to have problems such as poor fitting and gaps at the welding of the liquid cooling plate profile and the sealing plate, resulting in defects such as poor weld formation, lack of fusion, and welding leakage, so that the weld quality and product qualification rate cannot be guaranteed. The main welding method is continuous laser wire welding. The problem of assembly gap is inevitable during assembly, and key pit cracks are prone to occur at the key pit after laser welding, resulting in air leakage, unqualified pressure, and reduced product qualification rate. Therefore, it is necessary to add deposited metal to fill the gap during welding. The key pit at the light-receiving part is generally added with a lead-out plate at the end of the weld. After welding, the lead-out plate is removed, or manual TIG welding is used for direct repair. The continuous laser welding output energy is stable and continuous, but the heat input is large, and it is not easy to control welding deformation for thin plates. In view of the above-mentioned problems, it is very necessary to study and design a new laser welding method for the liquid cooling plate shell of new energy vehicles to overcome the problems existing in the existing automobile liquid cooling plate shell welding. Summary of the invention

[0004] The present invention proposes a laser welding method for a new energy vehicle liquid cooling plate shell to solve the problems of poor fitting, poor weld forming, welding deformation, air leakage, unqualified pressing, reduced product qualification rate and the need for repair in the existing welding of a liquid cooling plate shell of a vehicle.

[0005] The present invention provides a laser welding method for a liquid cooling plate shell of a new energy vehicle, comprising the following steps:

[0006] S1. Position the welding assembly tooling;

[0007] S2. The liquid cooling plate profile and the sealing plate are fixed on the welding assembly tooling;

[0008] S3. Set the welding system to determine the welding parameters and welding waveform, the welding waveform includes a pulse laser welding pulse waveform and a laser welding pulse waveform at the light receiving part, the pulse laser welding pulse waveform is a uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform, and the laser welding pulse waveform at the light receiving part is a uniform steep rise-continuous-uniform slow drop-uniform slow drop-uniform steep drop waveform;

[0009] S4. Adjust the angle of the laser head, welding gun and protective gas nozzle;

[0010] S5. The liquid cooling plate profile and the sealing plate are welded by the pulse laser of the pulse laser welding pulse waveform to obtain a weld, the laser light receiving point is stopped at the end of the weld, the laser welding pulse waveform at the light receiving point is used to adjust the end of the weld to obtain a liquid cooling plate shell, and the welding is stopped.

[0011] According to a laser welding method for a liquid cooling plate housing of a new energy vehicle in some embodiments of the present application, the welding assembly tooling includes a base plate, a liquid cooling plate support assembly, a sealing plate conformal assembly, a pneumatic clamping assembly, and a pneumatic limit assembly;

[0012] The upper surface of the base plate is provided with threaded holes, and the base plate is used for positioning the liquid cooling plate support assembly, the pneumatic clamping assembly and the pneumatic limit assembly;

[0013] The liquid cooling plate support assembly includes a first liquid cooling plate support block and a second liquid cooling plate support block, wherein the first liquid cooling plate support block and the second liquid cooling plate support block are respectively arranged on the left and right sides of the upper surface of the substrate, the first liquid cooling plate support block is used to support and position the left side of the liquid cooling plate profile, and the second liquid cooling plate support block is used to support and position the right side of the liquid cooling plate profile;

[0014] The sealing plate follower assembly includes a first sealing plate follower block and a second sealing plate follower block, the sealing plate includes a first sealing plate and a second sealing plate, the first sealing plate follower block is arranged at the upper end of the first sealing plate, and the first sealing plate follower block has the same shape as the first sealing plate, the first sealing plate follower block is used to press the liquid cooling plate profile and the first sealing plate, the second sealing plate follower block is arranged at the upper end of the second sealing plate, and the second sealing plate follower block has the same shape as the second sealing plate, and the second sealing plate follower block is used to press the liquid cooling plate profile and the second sealing plate;

[0015] The pneumatic clamping assembly includes a first pneumatic clamping device, a second pneumatic clamping device, a third pneumatic clamping device and a fourth pneumatic clamping device, the first pneumatic clamping device and the second pneumatic clamping device are respectively arranged on the front and rear sides of the first liquid-cooling plate support block, the first pneumatic clamping device and the second pneumatic clamping device are both used to limit the liquid-cooling plate profile and the sealing plate in the Z-axis direction, the third pneumatic clamping device and the fourth pneumatic clamping device are respectively arranged on the front and rear sides of the second liquid-cooling plate support block, and the third pneumatic clamping device and the fourth pneumatic clamping device are both used to limit the liquid-cooling plate profile and the sealing plate in the Z-axis direction;

[0016] The pneumatic limiting assembly includes a first pneumatic limiting device, a second pneumatic limiting device, a third pneumatic limiting device and a fourth pneumatic limiting device. The first pneumatic limiting device is arranged on the right side of the first pneumatic clamping device, and the first pneumatic limiting device is used to limit the first closing plate in the X-axis direction. The second pneumatic limiting device is arranged on the right side of the second pneumatic clamping device, and the second pneumatic limiting device is used to limit the first closing plate in the X-axis direction. The third pneumatic limiting device is arranged on the left side of the third pneumatic clamping device, and the third pneumatic limiting device is used to limit the second closing plate in the X-axis direction. The fourth pneumatic limiting device is arranged on the left side of the fourth pneumatic clamping device, and the fourth pneumatic limiting device is used to limit the second closing plate in the X-axis direction.

[0017] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, the first pneumatic clamping device includes a first pneumatic clamping support and a first pneumatic clamping arm connected to each other, the first pneumatic clamping support is connected to the base plate, and the first pneumatic clamping arm is arranged on the upper surface of the first sealing plate conforming block;

[0018] The second pneumatic pressing device comprises a second pneumatic pressing support and a second pneumatic pressing arm connected to each other, the second pneumatic pressing support is connected to the base plate, and the second pneumatic pressing arm is arranged on the upper surface of the first sealing plate conforming block;

[0019] The third pneumatic pressing device comprises a third pneumatic pressing support and a third pneumatic pressing arm which are connected to each other, the third pneumatic pressing support is connected to the base plate, and the third pneumatic pressing arm is arranged on the upper surface of the second sealing plate conforming block;

[0020] The fourth pneumatic pressing device comprises a fourth pneumatic pressing support and a fourth pneumatic pressing arm which are connected to each other, the fourth pneumatic pressing support is connected to the base plate, and the fourth pneumatic pressing arm is arranged on the upper surface of the second sealing plate conforming block;

[0021] The first pneumatic limiting device comprises a first pneumatic limiting support and a first pneumatic limiting arm connected to each other, the first pneumatic limiting support is connected to the base plate, and the first pneumatic limiting arm is arranged on the right side surface of the first sealing plate;

[0022] The second pneumatic limiting device comprises a second pneumatic limiting support and a second pneumatic limiting arm connected to each other, the second pneumatic limiting support is connected to the base plate, and the second pneumatic limiting arm is arranged on the right side surface of the first sealing plate;

[0023] The third pneumatic limiting device comprises a third pneumatic limiting support and a third pneumatic limiting arm connected to each other, the third pneumatic limiting support is connected to the base plate, and the third pneumatic limiting arm is arranged on the left side surface of the second sealing plate;

[0024] The fourth pneumatic limiting device includes a fourth pneumatic limiting support and a fourth pneumatic limiting arm connected to each other, the fourth pneumatic limiting support is connected to the base plate, and the fourth pneumatic limiting arm is arranged on the left side surface of the second sealing plate.

[0025] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, in step S3, the welding parameters include wire feeding speed, welding speed, defocus, spot diameter, shielding gas flow, pulse laser welding pulse waveform laser pulse duration, pulse laser welding pulse waveform frequency, laser pulse duration of laser welding pulse waveform at light collection and laser welding pulse waveform frequency at light collection, the wire feeding speed is 4-5m / min, the welding speed is 2.4-3m / min, the defocus is -3-3mm, the spot diameter is 0.42mm, the shielding gas flow is 25-30L / min, the pulse laser welding pulse waveform laser pulse duration is 30-40ms, the pulse laser welding pulse waveform frequency is 40-50Hz, the laser pulse duration of the laser welding pulse waveform at light collection is 100-150ms, and the laser welding pulse waveform frequency at light collection is 50-60Hz.

[0026] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, the uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform includes a first uniform steep rise stage, a first uniform steep drop stage, a first uniform slow drop stage and a steep drop stage.

[0027] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, the time t1 of the first uniform steep rise stage is 6ms~8ms, the starting laser power P1 of the first uniform steep rise stage is 150W~175W, and the end laser power P2 of the first uniform steep rise stage is 3000W~3500W; the time t2 of the first uniform steep drop stage is 6ms~8ms, and the end laser power P3 of the first uniform steep drop stage is 1200W~1400W; the time t3 of the first uniform slow drop stage is 18ms~24ms, and the end laser power P4 of the first uniform slow drop stage is 900W~1050W; the end laser power P5 of the steep drop stage is 150W~175W.

[0028] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, the uniform steep rise-continuous-uniform slow descent-uniform slow descent-uniform steep descent waveform includes a second uniform steep rise stage, a continuous stage, a second uniform slow descent stage, a third uniform slow descent stage and a fourth uniform slow descent stage.

[0029] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, the time t4 of the second uniform steep rise stage is 10ms to 15ms, the starting laser power P6 of the second uniform steep rise stage is 175W to 200W, and the end laser power P7 of the second uniform steep rise stage is 3500W to 40000W; the time t5 of the continuous stage is 40ms to 60ms, and the laser power P8 of the continuous stage is 3500W to 40000W; The time t6 of the second uniform speed slow descent stage is 20ms~30ms, and the terminal laser power P9 of the second uniform speed slow descent stage is 2800W~3200W; the time t7 of the third uniform speed slow descent stage is 10ms~15ms, and the terminal laser power P10 of the third uniform speed slow descent stage is 1750W~2000W; the time t8 of the fourth uniform speed slow descent stage is 20ms~30ms, and the terminal laser power P11 of the fourth uniform speed slow descent stage is 175W~200W.

[0030] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, in step S4, the angle between the laser head and the part to be welded is 80° to 84°, the angle between the welding gun and the part to be welded is 30° to 45°, and the angle between the shielding gas copper nozzle and the part to be welded is 20° to 30°.

[0031] According to a laser welding method for a liquid cooling plate shell of a new energy vehicle in some embodiments of the present application, in step S5, argon gas with a concentration of not less than 99.99% is used for front protection during the welding process.

[0032] The present invention proposes a laser welding method for a liquid cooling plate shell of a new energy vehicle, which adds a sealing plate conformal component, improves the fit of the workpiece, improves the welding quality, reduces welding defects and deformation problems, ensures the consistency of the product after welding, and changes the manual clamp and the tightening device to pneumatic clamping to reduce the working hours. The welding production efficiency is improved through the cooperation between manual and pneumatic clamping. The pulse waveform of the pulse laser welding is used to effectively improve the surface forming of the weld and the welding deformation. The laser welding pulse waveform is used at the light receiving point, and a pulse slow-down waveform is added to effectively suppress the generation of arc crater crack defects and solve the problem of key pit defects after laser welding. Through the present welding method, the problem of welding deformation can be effectively avoided, so that the liquid cooling plate after welding can be pressed to be qualified without leakage, thereby improving the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a process of laser welding a liquid cooling plate housing of a new energy vehicle according to the present invention;

[0034] Figure 2 It is a three-dimensional structural schematic diagram of the welding assembly tooling of the present invention;

[0035] Figure 3 The three-dimensional structural intention of the present invention is to fix the liquid cooling plate profile and the sealing plate on the welding assembly tooling;

[0036] Figure 4 It is a schematic diagram of the three-dimensional structure of the liquid cooling plate profile of the present invention;

[0037] Figure 5 It is a schematic diagram of the top view of the liquid cooling plate profile of the present invention;

[0038] Figure 6 It is a schematic diagram of the top view of the sealing plate of the present invention;

[0039] Figure 7 This is a schematic diagram of the pulse waveform of the pulse laser welding of the present invention;

[0040] Figure 8 It is a schematic diagram of the laser welding pulse waveform at the light receiving end of the present invention.

[0041] In the figure: 1, substrate, 2-1, first liquid cooling plate support block, 2-2, second liquid cooling plate support block, 3-1, first sealing plate following block, 3-2, second sealing plate following block, 4-1, first pneumatic clamping device, 4-2, second pneumatic clamping device, 4-3, third pneumatic clamping device, 4-4, fourth pneumatic clamping device, 5-1, first pneumatic limiting device, 5-2, second pneumatic limiting device, 5-3, third pneumatic limiting device, 5-4, fourth pneumatic limiting device, 6, liquid cooling plate profile, 7-1, first sealing plate, 7-2, second sealing plate, 8-1, first water nozzle, 8-2, second water nozzle. DETAILED DESCRIPTION

[0042] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0043] Embodiment 1, this embodiment provides a new energy vehicle liquid cooling plate shell laser welding method, such as Figure 1 As shown, the following steps are included:

[0044] S1. Position the welding assembly tooling;

[0045] S2. The liquid cooling plate profile 6 and the sealing plate are fixed to the welding assembly tooling;

[0046] S3. Set up the welding system, determine the welding parameters and welding waveform, the welding waveform includes a pulse laser welding pulse waveform and a laser welding pulse waveform at the light receiving end, the pulse laser welding pulse waveform is a uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform, and the laser welding pulse waveform at the light receiving end is a uniform steep rise-continuous-uniform slow drop-uniform slow drop-uniform steep drop waveform;

[0047] S4. Adjust the angle of the laser head, welding gun and protective gas nozzle;

[0048] S5. The liquid cooling plate profile 6 and the sealing plate are welded by a pulse laser with a pulse laser welding pulse waveform to obtain a weld, the laser light receiving point is stopped at the end of the weld, and the laser welding pulse waveform at the receiving point is used to adjust the end of the weld to obtain a liquid cooling plate shell, and the welding is stopped.

[0049] Embodiment 2: This embodiment provides a laser welding method for a liquid cooling plate shell of a new energy vehicle, comprising the following steps:

[0050] S1. Position the welding assembly tooling;

[0051] like Figure 2 and Figure 3 As shown, the welding assembly tooling includes a base plate 11, a liquid cooling plate support assembly, a sealing plate conforming assembly, a pneumatic clamping assembly and a pneumatic limit assembly;

[0052] The upper surface of the base plate 11 is provided with threaded holes, and the base plate 11 is used for positioning the liquid cooling plate support assembly, the pneumatic clamping assembly and the pneumatic limit assembly. In addition, the base plate 11 can also be fixed to the multi-hole tooling platform by bolts;

[0053] The liquid cooling plate support assembly includes a first liquid cooling plate support block 2-1 and a second liquid cooling plate support block 2-2, which are respectively arranged on the left and right sides of the upper surface of the substrate 11, and the first liquid cooling plate support block 2-1 is used to support and position the left side of the liquid cooling plate profile 6, and the second liquid cooling plate support block 2-2 is used to support and position the right side of the liquid cooling plate profile 6, and the material of the first liquid cooling plate support block 2-1 and the second liquid cooling plate support block 2-2 can be copper;

[0054] The sealing plate conforming assembly includes a first sealing plate conforming block 3-1 and a second sealing plate conforming block 3-2. Figure 6 As shown, the sealing plate includes a first sealing plate 7-1 and a second sealing plate 7-2, the first sealing plate following block 3-1 is arranged at the upper end of the first sealing plate 7-1, and the first sealing plate following block 3-1 has the same shape as the first sealing plate 7-1, the first sealing plate following block 3-1 is used to press the liquid cooling plate profile 6 and the first sealing plate 7-1, and the first sealing plate following block 3-1 can increase the fit between the first sealing plate 7-1 and the liquid cooling plate profile 6, and reduce the assembly gap between the first sealing plate 7-1 and the liquid cooling plate profile 6; the second sealing plate following block 3-2 is arranged at the upper end of the second sealing plate 7-2, and the second sealing plate following block 3-2 has the same shape as the second sealing plate 7-2, the second sealing plate following block 3-2 is used to press the liquid cooling plate profile 6 and the second sealing plate 7-2, and the second sealing plate following block 3-2 can increase the fit between the second sealing plate 7-2 and the liquid cooling plate profile 6, and reduce the assembly gap between the second sealing plate 7-2 and the liquid cooling plate profile 6;

[0055] The pneumatic clamping assembly includes a first pneumatic clamping device 4-1, a second pneumatic clamping device 4-2, a third pneumatic clamping device 4-3 and a fourth pneumatic clamping device 4-4. The first pneumatic clamping device 4-1 and the second pneumatic clamping device 4-2 are respectively arranged on the front and rear sides of the first liquid-cooling plate support block 2-1. The first pneumatic clamping device 4-1 and the second pneumatic clamping device 4-2 are both used to limit the liquid-cooling plate profile 6 and the sealing plate in the Z-axis direction. The third pneumatic clamping device 4-3 and the fourth pneumatic clamping device 4-4 are respectively arranged on the front and rear sides of the second liquid-cooling plate support block 2-2. The third pneumatic clamping device 4-3 and the fourth pneumatic clamping device 4-4 are both used to limit the liquid-cooling plate profile 6 and the sealing plate in the Z-axis direction; the first pneumatic clamping device 4-1, the second pneumatic clamping device 4-2, the third pneumatic clamping device 4-3 and the fourth pneumatic clamping device 4-4 are respectively controlled by four independent cylinders;

[0056] More specifically, the first pneumatic clamping device 4-1 includes a first pneumatic clamping support and a first pneumatic clamping arm connected to each other, the first pneumatic clamping support is connected to the substrate 1, and the first pneumatic clamping arm is arranged on the upper surface of the first sealing plate follower block 3-1; the second pneumatic clamping device 4-2 includes a second pneumatic clamping support and a second pneumatic clamping arm connected to each other, the second pneumatic clamping support is connected to the substrate 1, and the second pneumatic clamping arm is arranged on the upper surface of the first sealing plate follower block 3-1; the third pneumatic clamping device 4-3 includes a third pneumatic clamping support and a third pneumatic clamping arm connected to each other, the third pneumatic clamping support is connected to the substrate 1, and the third pneumatic clamping arm is arranged on the upper surface of the second sealing plate follower block 3-2; the fourth pneumatic clamping device 4-4 includes a fourth pneumatic clamping support and a fourth pneumatic clamping arm connected to each other, the fourth pneumatic clamping support is connected to the substrate 1, and the fourth pneumatic clamping arm is arranged on the upper surface of the second sealing plate follower block 3-2;

[0057] The pneumatic limiting assembly includes a first pneumatic limiting device 5-1, a second pneumatic limiting device 5-2, a third pneumatic limiting device 5-3 and a fourth pneumatic limiting device 5-4. The first pneumatic limiting device 5-1 is arranged on the right side of the first pneumatic clamping device 4-1. The first pneumatic limiting device 5-1 is used to limit the first sealing plate 7-1 in the X-axis direction. The second pneumatic limiting device 5-2 is arranged on the right side of the second pneumatic clamping device 4-2. The second pneumatic limiting device 5-2 is used to limit the first sealing plate 7-1 in the X-axis direction. The third pneumatic limiting device 5-4 is arranged on the right side of the second pneumatic clamping device 4-2. The dynamic limit device 5-3 is arranged on the left side of the third pneumatic clamping device 4-3, and the third pneumatic limit device 5-3 is used to limit the second sealing plate 7-2 in the X-axis direction. The fourth pneumatic limit device 5-4 is arranged on the left side of the fourth pneumatic clamping device 4-4, and the fourth pneumatic limit device 5-4 is used to limit the second sealing plate 7-2 in the X-axis direction; the first pneumatic limit device 5-1, the second pneumatic limit device 5-2, the third pneumatic limit device 5-3 and the fourth pneumatic limit device 5-4 are respectively controlled by four independent cylinders;

[0058] More specifically, the first pneumatic limit device 5-1 includes a first pneumatic limit support and a first pneumatic limit arm connected to each other, the first pneumatic limit support is connected to the substrate 1, and the first pneumatic limit arm is arranged on the right side surface of the first sealing plate 7-1; the second pneumatic limit device 5-2 includes a second pneumatic limit support and a second pneumatic limit arm connected to each other, the second pneumatic limit support is connected to the substrate 1, and the second pneumatic limit arm is arranged on the right side surface of the first sealing plate 7-1; the third pneumatic limit device 5-3 includes a third pneumatic limit support and a third pneumatic limit arm connected to each other, the third pneumatic limit support is connected to the substrate 1, and the third pneumatic limit arm is arranged on the left side surface of the second sealing plate 7-2; the fourth pneumatic limit device 5-4 includes a fourth pneumatic limit support and a fourth pneumatic limit arm connected to each other, the fourth pneumatic limit support is connected to the substrate 1, and the fourth pneumatic limit arm is arranged on the left side surface of the second sealing plate 7-2;

[0059] In addition, if Figure 4 and Figure 5 As shown, the liquid cooling plate profile 6 is also provided with a first water nozzle 8-1 and a second water nozzle 8-2. The first water nozzle 8-1 can be a water inlet and also serves as a positioning pin for installing the liquid cooling plate profile 6. The second water nozzle 8-2 can be a water outlet and also serves as a positioning pin for installing the profile.

[0060] S2. Fix the liquid cooling plate profile 6 and the sealing plate on the welding assembly tooling. In this embodiment, the thickness of the sealing plate is 1.2 mm, and the thickness of the liquid cooling plate profile 6 is 1.5 mm. After the liquid cooling plate profile 6 and the sealing plate are fixed in position by the pneumatic limiter assembly, the sealing plate follower assembly is manually pressed onto the sealing plate, and it is pressed and fixed by the pneumatic clamping assembly;

[0061] S3. Set the welding system and determine the welding parameters and welding waveform. The welding waveform includes the pulse waveform of pulse laser welding and the pulse waveform of laser welding at the light receiving part, such as Figure 7 As shown in the figure, the pulse waveform of pulse laser welding is a uniform rapid rise-uniform rapid drop-uniform slow drop-steep drop waveform, such as Figure 8 As shown, the laser welding pulse waveform at the light receiving part is a waveform of uniform rapid rise-continuous-uniform slow fall-uniform slow fall-uniform steep fall;

[0062] Specifically, the welding parameters include wire feeding speed, welding speed, defocus, spot diameter, shielding gas flow, pulse laser welding pulse waveform laser pulse duration, pulse laser welding pulse waveform frequency, laser pulse duration of laser welding pulse waveform at light receiving and laser welding pulse waveform frequency at light receiving. The wire feeding speed is 4-5m / min, the welding speed is 2.4-3m / min, the defocus is -3-3mm, the spot diameter is 0.42mm, the shielding gas flow is 25-30L / min, the pulse laser welding pulse waveform laser pulse duration is 30-40ms, the pulse laser welding pulse waveform frequency is 40-50Hz, the laser welding pulse waveform laser pulse duration at light receiving is 100-150ms, and the laser welding pulse waveform frequency at light receiving is 50-60Hz.

[0063] More specifically, Figure 7 As shown, the uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform includes a first uniform steep rise stage, a first uniform steep drop stage, a first uniform slow drop stage and a steep drop stage; wherein, the time t1 of the first uniform steep rise stage is 6ms-8ms, the starting laser power P1 of the first uniform steep rise stage is 150W-175W, and the end laser power P2 of the first uniform steep rise stage is 3000W-3500W. By setting the first uniform steep rise stage, the surface state of the metal can be quickly changed by utilizing the peak that appears at the beginning, so that the surface temperature of the metal rises to the melting point, thereby reducing the surface reflectivity of the material, forming a keyhole plasma, and increasing Energy absorption increases the melting depth of the metal surface; the time t2 of the first uniform steep drop stage is 6ms to 8ms, and the terminal laser power P3 of the first uniform steep drop stage is 1200W to 1400W. By setting the first uniform steep drop stage, the welding work can be completed while saving energy; the time t3 of the first uniform slow drop stage is 18ms to 24ms, and the terminal laser power P4 of the first uniform slow drop stage is 900W to 1050W. By setting the first uniform slow drop stage, the energy is slowly reduced, the cooling speed of the metal solidification process is controlled, and the internal stress of the metal is reduced; the terminal laser power P5 of the steep drop stage is 150W to 175W;

[0064] More specifically, Figure 8As shown, the uniform steep rise-continuous-uniform slow descent-uniform slow descent-uniform steep descent waveform includes a second uniform steep rise stage, a continuous stage, a second uniform slow descent stage, a third uniform slow descent stage and a fourth uniform slow descent stage; wherein, the time t4 of the second uniform steep rise stage is 10ms-15ms, the starting laser power P6 of the second uniform steep rise stage is 175W-200W, and the end laser power P7 of the second uniform steep rise stage is 3500W-40000W. By setting the second uniform steep rise stage, the surface state of the metal can be quickly changed, so that the surface temperature of the metal rises to the melting point, thereby reducing the reflectivity of the metal surface; the time t5 of the continuous stage is 40ms-60ms, and the laser power P8 of the continuous stage is 3500W-40000W. In the continuous stage, the laser power is always maintained at the peak power. The continuous stage is a balance section, and a stable intensity input energy is used. The second uniform speed steep rise stage and the continuous stage can fully stir the molten metal; the time t6 of the second uniform speed slow decline stage is 20ms~30ms, and the terminal laser power P9 of the second uniform speed slow decline stage is 2800W~3200W. By setting the second uniform speed slow decline stage, the laser energy is slowly reduced and the weld temperature is slowly reduced; the time t7 of the third uniform speed slow decline stage is 10ms~15ms, and the terminal laser power P10 of the third uniform speed slow decline stage is 1750W~2000W; the time t8 of the fourth uniform speed slow decline stage is 20ms~30ms, and the terminal laser power P11 of the fourth uniform speed slow decline stage is 175W~200W; the three slowly declining waveform sections of the second uniform speed slow decline stage, the third uniform speed slow decline stage and the fourth uniform speed slow decline stage are set to avoid extreme cooling of aluminum alloy high thermal conductivity materials after welding, and effectively avoid the generation of key pit crack defects.

[0065] S4. Adjust the angle of the laser head, welding gun and protective gas nozzle;

[0066] Specifically, the angle between the laser head and the part to be welded is 80° to 84°, the angle between the welding gun and the part to be welded is 30° to 45°, and the angle between the shielding gas copper nozzle and the part to be welded is 20° to 30°;

[0067] S5. The liquid cooling plate profile 6 and the sealing plate are welded by a pulsed laser with a pulsed laser welding pulse waveform to obtain a weld, the laser light receiving point is stopped at the end of the weld, and the end of the weld is adjusted by using the laser welding pulse waveform at the receiving point to obtain a liquid cooling plate shell, and the welding is stopped. The first sealing plate 7-1 is a sealing plate on the left side of the liquid cooling plate shell, which is connected to the left side of the liquid cooling plate profile 6, and a closed water channel is formed inside. The second sealing plate 7-2 is a sealing plate on the right side of the liquid cooling plate shell, which is connected to the right side of the liquid cooling plate profile 6, and a closed water channel is formed inside.

[0068] Specifically, during the welding process, front protection is performed by argon gas with a concentration of not less than 99.99%.

[0069] Embodiment 3, this embodiment provides a laser welding method for a liquid cooling plate shell of a new energy vehicle, using the welding assembly tooling mentioned in Embodiment 2 for welding, specifically comprising the following steps:

[0070] S1. Tool positioning: Position the welding assembly tool, place the substrate 11 within the working range of the laser head of the welding robot, position the substrate 11 on the porous platform through bolts, and install the liquid cooling plate support assembly, pneumatic clamping assembly and pneumatic limit assembly in the specified positions in sequence;

[0071] S2. Loading: Fix the liquid cooling plate profile 6 and the sealing plate on the welding assembly tooling, place the liquid cooling plate profile 6 on the upper ends of the first liquid cooling plate support block 2-1 and the second liquid cooling plate support block 2-2, pass the positioning pins through the first water nozzle 8-1 and the second water nozzle 8-2 from top to bottom and fix them on the base plate 11, position the liquid cooling plate profile 6, and then place the first sealing plate 7-1 and the second sealing plate 7-2, respectively, and use the first pneumatic limit device 5-1 and the second pneumatic limit device 5-2 to The first sealing plate 7-1 is positioned, and the second sealing plate 7-2 is positioned by the third pneumatic limiting device 5-3 and the fourth pneumatic limiting device 5-4, the first sealing plate following block 3-1 is placed on the upper end of the first sealing plate 7-1, and is pressed and fixed by the first pneumatic clamping device 4-1 and the second pneumatic clamping device 4-2, and the second sealing plate following block 3-2 is placed on the upper end of the second sealing plate 7-2, and is pressed and fixed by the third pneumatic clamping device 4-3 and the fourth pneumatic clamping device 4-4;

[0072] S3. Set up the welding system, determine the welding parameters and welding waveform, the welding waveform includes a pulse laser welding pulse waveform and a laser welding pulse waveform at the light receiving end, the pulse laser welding pulse waveform is a uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform, and the laser welding pulse waveform at the light receiving end is a uniform steep rise-continuous-uniform slow drop-uniform slow drop-uniform steep drop waveform;

[0073] The welding parameters include wire feeding speed, welding speed, defocus, spot diameter, shielding gas flow, pulse laser welding pulse waveform laser pulse duration, pulse laser welding pulse waveform frequency, laser pulse duration of laser welding pulse waveform at the light receiving end and laser welding pulse waveform frequency at the light receiving end. The wire feeding speed is 4m / min, the welding speed is 2.4m / min, the defocus is 0mm, the spot diameter is 0.42mm, the shielding gas flow is 25L / min, the pulse laser welding pulse waveform laser pulse duration is 34ms, the pulse laser welding pulse waveform frequency is 40Hz, the laser pulse duration of laser welding pulse waveform at the light receiving end is 120ms, and the laser welding pulse waveform frequency at the light receiving end is 50Hz.

[0074] The uniform steep rise-uniform steep fall-uniform slow fall-steep fall waveform includes a first uniform steep rise stage, a first uniform steep fall stage, a first uniform slow fall stage and a steep fall stage; wherein, the time t1 of the first uniform steep rise stage is 6ms, the starting laser power P1 of the first uniform steep rise stage is 150W, and the end laser power P2 of the first uniform steep rise stage is 3000W. By setting the first uniform steep rise stage, the surface state of the metal can be quickly changed by utilizing the peak that appears at the beginning, so that the surface temperature of the metal rises to the melting point, thereby reducing the surface reflectivity of the material, forming a keyhole plasma. body, increasing energy absorption to increase the metal surface melting depth; the time t2 of the first uniform steep drop stage is 8ms, and the terminal laser power P3 of the first uniform steep drop stage is 1200W. By setting the first uniform steep drop stage, the welding work can be completed while saving energy; the time t3 of the first uniform slow drop stage is 20ms, and the terminal laser power P4 of the first uniform slow drop stage is 900W. By setting the first uniform slow drop stage, the energy is slowly reduced to control the cooling speed of the metal solidification process and reduce the internal stress of the metal; the terminal laser power P5 of the steep drop stage is 150W;

[0075] The uniform steep rise-continuous-uniform slow descent-uniform slow descent-uniform steep descent waveform includes a second uniform steep rise stage, a continuous stage, a second uniform slow descent stage, a third uniform slow descent stage and a fourth uniform slow descent stage; wherein, the time t4 of the second uniform steep rise stage is 10ms, the starting laser power P6 of the second uniform steep rise stage is 175W, and the end laser power P7 of the second uniform steep rise stage is 3500W. By setting the second uniform steep rise stage, the surface state of the metal can be quickly changed, so that the surface temperature of the metal rises to the melting point, thereby reducing the reflectivity of the metal surface; the time t5 of the continuous stage is 50ms, and the laser power P8 of the continuous stage is 3500W. In the continuous stage, the laser power is always maintained at the peak power. The continuous stage is a balance stage, and a stable intensity input energy is used. The second uniform speed steep rise stage and the continuous stage can fully stir the molten metal; the time t6 of the second uniform speed slow down stage is 20ms, and the terminal laser power P9 of the second uniform speed slow down stage is 2800W. By setting the second uniform speed slow down stage, the laser energy is slowly reduced and the weld temperature is slowly reduced; the time t7 of the third uniform speed slow down stage is 10ms, and the terminal laser power P10 of the third uniform speed slow down stage is 1750W; the time t8 of the fourth uniform speed slow down stage is 30ms, and the terminal laser power P11 of the fourth uniform speed slow down stage is 175W; the three-stage slow down waveform sections of the second uniform speed slow down stage, the third uniform speed slow down stage and the fourth uniform speed slow down stage are set to avoid extreme cold after welding of aluminum alloy high thermal conductivity materials, and effectively avoid the generation of key pit crack defects;

[0076] S4. Adjust the angle of the laser head, welding gun and protective gas nozzle;

[0077] The angle between the laser head and the part to be welded is 84°, the angle between the welding gun and the part to be welded is 30°, and the angle between the shielding gas copper nozzle and the part to be welded is 20°;

[0078] S5. The liquid cooling plate profile 6 and the sealing plate are welded by a pulsed laser with a pulsed laser welding pulse waveform to obtain a weld, the laser light receiving point is stopped at the end of the weld, and the end of the weld is adjusted by using the laser welding pulse waveform at the receiving point to obtain a liquid cooling plate shell, and the welding is stopped. The first sealing plate 7-1 is a sealing plate on the left side of the liquid cooling plate shell, which is connected to the left side of the liquid cooling plate profile 6, and a closed water channel is formed inside. The second sealing plate 7-2 is a sealing plate on the right side of the liquid cooling plate shell, which is connected to the right side of the liquid cooling plate profile 6, and a closed water channel is formed inside.

[0079] During the welding process, due to the interference between the pressure arm and the laser welding equipment, the weld needs to be welded in sections. The first sealing plate 7-1 and the second sealing plate 7-2 are both divided into two sections for welding. The first sealing plate 7-1 and the second sealing plate 7-2 are both 1.2mm5xxx aluminum alloy, and the liquid cooling plate profile 6 is 1.5mm6xxx aluminum alloy. First, use the second pneumatic clamping device 4-2 and the third pneumatic clamping device 4-3 to clamp the outer sides of the first sealing plate 7-1 and the second sealing plate 7-2 respectively. Carry out welding. After welding is completed, lift the second pneumatic clamping arm of the second pneumatic clamping device 4-2 and the third pneumatic clamping arm of the third pneumatic clamping device 4-3, clamp the first pneumatic clamping arm of the first pneumatic clamping device 4-1 and the fourth pneumatic clamping arm of the fourth pneumatic clamping device 4-4, complete the inner side welding of the first sealing plate 7-1 and the second sealing plate 7-2, and stop the laser light collection point on the weld. Through the adjustment of the light collection pulse process, eliminate the arc pit defect and avoid welding leakage repair.

[0080] During welding, the front side is protected by argon gas with a concentration of not less than 99.99%;

[0081] This embodiment also includes welding of the first water nozzle 8-1 and the second water nozzle 8-2: after laser welding, the workpiece is removed, and the first water nozzle 8-1 and the second water nozzle 8-2 are welded by manual TIG welding, with a welding current of 120A, a voltage of 13.1V, a welding speed of 0.09m / min, and a shielding gas flow rate of 15L / min.

[0082] Quality inspection: Perform air tightness inspection on the liquid cooling plate shell after welding, use 350KPa±5KPa air pressure to inflate the liquid cooling plate, maintain the pressure for 60s, and no leakage occurs.

[0083] Example 4. This example provides a laser welding method for the shell of a liquid cooling plate of a new energy vehicle. The welding assembly tool used in Example 3 is used for welding, and some experimental steps and conditions are the same as those in Example 3. The difference from Example 3 is that in this example, the laser pulse duration of the pulse laser welding pulse waveform is 35 ms, the pulse laser welding pulse waveform frequency is 45 Hz, the laser pulse duration of the laser welding pulse waveform at the light receiving point is 130 ms, and the laser welding pulse waveform frequency at the light receiving point is 55 Hz; the starting laser power P1 of the first uniform and steep rise stage is 160 W, and the end laser power P2 of the first uniform and steep rise stage is 3200W; the terminal laser power P3 of the first uniform steep descent stage is 1280W; the terminal laser power P4 of the first uniform slow descent stage is 960W; the terminal laser power P5 of the steep descent stage is 160W; the starting laser power P6 of the second uniform steep rise stage is 185W, and the terminal laser power P7 of the second uniform steep rise stage is 3700W; the laser power P8 of the continuous stage is 3700W; the terminal laser power P9 of the second uniform slow descent stage is 2960W; the terminal laser power P10 of the third uniform slow descent stage is 1850W; the terminal laser power P11 of the fourth uniform slow descent stage is 185W;

[0084] The quality inspection result of the liquid cooling plate produced in this embodiment is as follows: the air tightness of the liquid cooling plate shell after welding is inspected, the liquid cooling plate is inflated with air at a pressure of 350 KPa ± 5 KPa, and the pressure is maintained for 60 seconds, and no leakage occurs.

[0085] Example 5. This example provides a laser welding method for the shell of a liquid cooling plate of a new energy vehicle. The welding assembly tool used in Example 3 is used for welding, and some experimental steps and conditions are the same as those in Example 3. The difference from Example 3 is that in this example, the wire feeding speed is 4.5 m / min, the welding speed is 2.6 m / min, the pulse laser welding pulse waveform laser pulse duration is 40 ms, the pulse laser welding pulse waveform frequency is 47 Hz, the laser welding pulse waveform laser pulse duration at the light receiving end is 140 ms, and the laser welding pulse waveform frequency at the light receiving end is 58 Hz; the starting laser power P1 of the first uniform speed steep rise stage is 170 W, and the first uniform speed The terminal laser power P2 of the steep rise stage is 3400W; the terminal laser power P3 of the first uniform steep drop stage is 1360W; the terminal laser power P4 of the first uniform slow drop stage is 1020W; the terminal laser power P5 of the steep drop stage is 170W; the starting laser power P6 of the second uniform steep rise stage is 195W, and the terminal laser power P7 of the second uniform steep rise stage is 3900W; the laser power P8 of the continuous stage is 3900W; the terminal laser power P9 of the second uniform slow drop stage is 3120W; the terminal laser power P10 of the third uniform slow drop stage is 1950W; the terminal laser power P11 of the fourth uniform slow drop stage is 195W;

[0086] The quality inspection result of the liquid cooling plate produced in this embodiment is as follows: the air tightness of the liquid cooling plate shell after welding is inspected, the liquid cooling plate is inflated with air at a pressure of 350 KPa ± 5 KPa, and the pressure is maintained for 60 seconds, and no leakage occurs.

[0087] Comparative Example 1. This comparative example provides a laser welding method for the liquid cooling plate shell of a new energy vehicle. The welding assembly tooling used in Example 3 is used for welding, and some experimental steps and conditions are the same as those in Example 3. The difference from Example 3 is that in this comparative example, traditional continuous laser welding is adopted. Without adding pulse laser welding pulse waveform and laser welding pulse waveform at the receiving end, the laser power is set to 3.5kW, the welding speed is 2.4m / min, the defocus amount is 0, the wire feeding speed is 4.0m / min, and high-purity argon gas with a concentration of not less than 99.99% is used for front protection during welding, and the gas flow rate is 25L / min.

[0088] The quality inspection results of the liquid cooling plate produced in this comparative example are as follows: the air tightness of the liquid cooling plate shell after welding is inspected, and the liquid cooling plate is inflated with 350KPa±5KPa air pressure, and the pressure is maintained for 60s. Due to the appearance of arc crater cracks at the weld finish and a small amount of bubbles at the cracks, the inspection result is unqualified.

[0089] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A laser welding method for a liquid cooling plate shell of a new energy vehicle, characterized in that: The steps include: S1. Position the welding assembly tooling; S2. The liquid cooling plate profile (6) and the sealing plate are fixed on the welding assembly tooling; S3. Set the welding system to determine the welding parameters and welding waveform, the welding waveform includes a pulse laser welding pulse waveform and a laser welding pulse waveform at the light receiving part, the pulse laser welding pulse waveform is a uniform steep rise-uniform steep drop-uniform slow drop-steep drop waveform, and the laser welding pulse waveform at the light receiving part is a uniform steep rise-continuous-uniform slow drop-uniform slow drop-uniform steep drop waveform; S4. Adjust the angle of the laser head, welding gun and protective gas nozzle; S5. The liquid cooling plate profile (6) and the sealing plate are welded by using the pulse laser of the pulse laser welding pulse waveform to obtain a weld, the laser light receiving point is stopped at the end of the weld, and the laser welding pulse waveform at the light receiving point is used to adjust the end of the weld to obtain a liquid cooling plate shell, and the welding is stopped.

2. A laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1, characterized in that: The welding assembly tool comprises a base plate (1), a liquid cooling plate support assembly, a sealing plate conforming assembly, a pneumatic pressing assembly and a pneumatic limiting assembly; The upper surface of the base plate (1) is provided with threaded holes, and the base plate (1) is used for positioning the liquid cooling plate support assembly, the pneumatic pressing assembly and the pneumatic limiting assembly; The liquid cooling plate support assembly comprises a first liquid cooling plate support block (2-1) and a second liquid cooling plate support block (2-2), wherein the first liquid cooling plate support block (2-1) and the second liquid cooling plate support block (2-2) are respectively arranged on the left and right sides of the upper surface of the base plate (1), the first liquid cooling plate support block (2-1) is used to support and position the left side of the liquid cooling plate profile (6), and the second liquid cooling plate support block (2-2) is used to support and position the right side of the liquid cooling plate profile (6); The sealing plate follower assembly comprises a first sealing plate follower block (3-1) and a second sealing plate follower block (3-2), the sealing plate comprises a first sealing plate (7-1) and a second sealing plate (7-2), the first sealing plate follower block (3-1) is arranged at the upper end of the first sealing plate (7-1), and the first sealing plate follower block (3-1) and the first sealing plate (7-1) have the same shape, the first sealing plate follower block (3-1) is used to press the liquid cooling plate profile (6) and the first sealing plate (7-1), the second sealing plate follower block (3-2) is arranged at the upper end of the second sealing plate (7-2), and the second sealing plate follower block (3-2) and the second sealing plate (7-2) have the same shape, and the second sealing plate follower block (3-2) is used to press the liquid cooling plate profile (6) and the second sealing plate (7-2); The pneumatic clamping assembly comprises a first pneumatic clamping device (4-1), a second pneumatic clamping device (4-2), a third pneumatic clamping device (4-3) and a fourth pneumatic clamping device (4-4); the first pneumatic clamping device (4-1) and the second pneumatic clamping device (4-2) are respectively arranged on the front and rear sides of the first liquid cooling plate support block (2-1); the first pneumatic clamping device (4-1) and the second pneumatic clamping device (4-2) are both used to limit the position of the liquid cooling plate profile (6) and the sealing plate in the Z-axis direction; the third pneumatic clamping device (4-3) and the fourth pneumatic clamping device (4-4) are respectively arranged on the front and rear sides of the second liquid cooling plate support block (2-2); the third pneumatic clamping device (4-3) and the fourth pneumatic clamping device (4-4) are both used to limit the position of the liquid cooling plate profile (6) and the sealing plate in the Z-axis direction; The pneumatic limiting assembly comprises a first pneumatic limiting device (5-1), a second pneumatic limiting device (5-2), a third pneumatic limiting device (5-3) and a fourth pneumatic limiting device (5-4), wherein the first pneumatic limiting device (5-1) is arranged on the right side of the first pneumatic pressing device (4-1), and the first pneumatic limiting device (5-1) is used to limit the first sealing plate (7-1) in the X-axis direction, the second pneumatic limiting device (5-2) is arranged on the right side of the second pneumatic pressing device (4-2), and the second The pneumatic limiting device (5-2) is used to limit the first sealing plate (7-1) in the X-axis direction, the third pneumatic limiting device (5-3) is arranged on the left side of the third pneumatic pressing device (4-3), and the third pneumatic limiting device (5-3) is used to limit the second sealing plate (7-2) in the X-axis direction, and the fourth pneumatic limiting device (5-4) is arranged on the left side of the fourth pneumatic pressing device (4-4), and the fourth pneumatic limiting device (5-4) is used to limit the second sealing plate (7-2) in the X-axis direction.

3. A laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 2, characterized in that: The first pneumatic pressing device (4-1) comprises a first pneumatic pressing support and a first pneumatic pressing arm which are connected to each other, the first pneumatic pressing support is connected to the base plate (1), and the first pneumatic pressing arm is arranged on the upper surface of the first sealing plate follower block (3-1); The second pneumatic pressing device (4-2) comprises a second pneumatic pressing support and a second pneumatic pressing arm which are connected to each other, the second pneumatic pressing support is connected to the base plate (1), and the second pneumatic pressing arm is arranged on the upper surface of the first sealing plate follower block (3-1); The third pneumatic pressing device (4-3) comprises a third pneumatic pressing support and a third pneumatic pressing arm which are connected to each other, the third pneumatic pressing support is connected to the base plate (1), and the third pneumatic pressing arm is arranged on the upper surface of the second sealing plate follower block (3-2); The fourth pneumatic pressing device (4-4) comprises a fourth pneumatic pressing support and a fourth pneumatic pressing arm which are connected to each other, the fourth pneumatic pressing support is connected to the base plate (1), and the fourth pneumatic pressing arm is arranged on the upper surface of the second sealing plate follower block (3-2); The first pneumatic limiting device (5-1) comprises a first pneumatic limiting support and a first pneumatic limiting arm which are connected to each other, the first pneumatic limiting support is connected to the base plate (1), and the first pneumatic limiting arm is arranged on the right side surface of the first sealing plate (7-1); The second pneumatic limiting device (5-2) comprises a second pneumatic limiting support and a second pneumatic limiting arm which are connected to each other, the second pneumatic limiting support is connected to the base plate (1), and the second pneumatic limiting arm is arranged on the right side surface of the first sealing plate (7-1); The third pneumatic limiting device (5-3) comprises a third pneumatic limiting support and a third pneumatic limiting arm which are connected to each other, the third pneumatic limiting support is connected to the base plate (1), and the third pneumatic limiting arm is arranged on the left side surface of the second sealing plate (7-2); The fourth pneumatic limiting device (5-4) comprises a fourth pneumatic limiting support and a fourth pneumatic limiting arm which are connected to each other, the fourth pneumatic limiting support is connected to the base plate (1), and the fourth pneumatic limiting arm is arranged on the left side surface of the second sealing plate (7-2).

4. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1 is characterized in that: In the step S3, the welding parameters include wire feeding speed, welding speed, defocus, spot diameter, shielding gas flow, pulse laser welding pulse waveform laser pulse duration, pulse laser welding pulse waveform frequency, laser pulse duration of laser welding pulse waveform at light receiving point and laser welding pulse waveform frequency at light receiving point. The wire feeding speed is 4-5m / min, the welding speed is 2.4-3m / min, the defocus is -3-3mm, the spot diameter is 0.42mm, the shielding gas flow is 25-30L / min, the pulse laser welding pulse waveform laser pulse duration is 30-40ms, the pulse laser welding pulse waveform frequency is 40-50Hz, the laser pulse duration of the laser welding pulse waveform at light receiving point is 100-150ms, and the laser welding pulse waveform frequency at light receiving point is 50-60Hz.

5. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1 is characterized in that: The uniform speed steep rise-uniform speed steep fall-uniform speed slow fall-steep fall waveform includes a first uniform speed steep rise stage, a first uniform speed steep fall stage, a first uniform speed slow fall stage and a steep fall stage.

6. A laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 5, characterized in that: The time t1 of the first uniform steep rise stage is 6ms~8ms, the starting laser power P1 of the first uniform steep rise stage is 150W~175W, and the end laser power P2 of the first uniform steep rise stage is 3000W~3500W; the time t2 of the first uniform steep drop stage is 6ms~8ms, and the end laser power P3 of the first uniform steep drop stage is 1200W~1400W; the time t3 of the first uniform slow drop stage is 18ms~24ms, and the end laser power P4 of the first uniform slow drop stage is 900W~1050W; the end laser power P5 of the steep drop stage is 150W~175W.

7. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1 is characterized in that: The uniform speed steep rise-continuous-uniform speed slow fall-uniform speed slow fall-uniform speed steep fall waveform includes a second uniform speed steep rise stage, a continuous stage, a second uniform speed slow fall stage, a third uniform speed slow fall stage and a fourth uniform speed slow fall stage.

8. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 7 is characterized in that: The time t4 of the second uniform steep rise stage is 10ms~15ms, the starting laser power P6 of the second uniform steep rise stage is 175W~200W, and the end laser power P7 of the second uniform steep rise stage is 3500W~40000W; the time t5 of the continuous stage is 40ms~60ms, and the laser power P8 of the continuous stage is 3500W~40000W; the time t6 of the second uniform slow decline stage is 20ms~30ms, and the end laser power P9 of the second uniform slow decline stage is 2800W~3200W; the time t7 of the third uniform slow decline stage is 10ms~15ms, and the end laser power P10 of the third uniform slow decline stage is 1750W~2000W; the time t8 of the fourth uniform slow decline stage is 20ms~30ms, and the end laser power P11 of the fourth uniform slow decline stage is 175W~200W.

9. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1 is characterized in that: In step S4, the angle between the laser head and the part to be welded is 80° to 84°, the angle between the welding gun and the part to be welded is 30° to 45°, and the angle between the shielding gas copper nozzle and the part to be welded is 20° to 30°.

10. The laser welding method for a liquid cooling plate housing of a new energy vehicle according to claim 1, characterized in that: In the step S5, front protection is performed during welding by using argon gas with a concentration of not less than 99.99%.

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