Method and system for welding water nozzle and liquid cooling plate in aluminum alloy battery tray

Abstract

The invention discloses a welding method and system for a water nozzle and a liquid cooling plate in an aluminum alloy battery tray. The method comprises the steps that S1, a welding robot drives a welding gun to do periodic swing motion along a welding seam track of a to-be-welded workpiece, and the path of the swing motion stretches across the two sides of a welding seam; s2, at least one welding transition point is arranged along the track of the welding seam, the welding seam is divided into N sections of welding sub-paths, and the welding heat input quantity of the tail section of the two adjacent sections of welding sub-paths is lower than the welding heat input quantity of the front section of the two adjacent sections of welding sub-paths; s3, in the swinging process of the welding gun, the position of the tip end of the welding gun is detected in real time, and when the welding gun swings to the first side area, the output CMT technology is triggered; and when the welding gun swings to the second side area, the pulse arc process is switched. The welding quality and stability of a welding joint with large plate thickness difference are effectively guaranteed, and the adverse effect on the welding quality caused by overheating of the rear half section plate of the small-radius circular welding seam is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of welding technology, and in particular to a welding method and system for a water nozzle and a liquid cooling plate in an aluminum alloy battery tray. Background Art

[0002] The battery tray of new energy vehicles is the main load-bearing structural component of the power battery, and its welding quality is related to the safety of the battery and the entire vehicle.

[0003] During the welding process of the aluminum alloy battery tray, the welding of the liquid cooling plate and the water nozzle is the most difficult and risky. This is because the thickness of the liquid cooling plate is only 1.5mm, and the thickness of the water nozzle is generally more than 5mm. When the two are welded, due to the large difference in plate thickness and the circular weld.

[0004] When using ordinary CMT arc welding process for welding, due to the limited heat input of CMT welding, it is only suitable for thin plates below 3mm. Therefore, for welding joints with large differences in welding plate thickness, it is easy to have welding penetration on one side of the liquid cooling plate and insufficient penetration on the water nozzle side, resulting in poor joint forming and affecting the strength and sealing of the welded joint.

[0005] In order to solve the welding difficulties of the water nozzle and the liquid cooling plate, the existing technical solution is to adopt the laser wire welding process. This is because the laser line energy is very high and the heat affected zone is very small. The liquid cooling plate will not be burned through during welding. When welding, the direction is pointed to the water nozzle side, which can ensure that the melting depth on one side of the water nozzle meets the requirements.

[0006] However, compared with the CMT welding process, the laser wire welding process has the following three shortcomings: First, the cost of laser wire welding is much higher than that of CMT welding process.

[0007] Second, laser wire welding has extremely high requirements for the assembly accuracy and surface cleanliness of the workpiece, and debugging is difficult.

[0008] Third, due to the limited heat input of laser wire welding and the thick thickness of the nozzle, the welding speed is slow, which affects the production rhythm of the entire battery tray production line.

[0009] It can be seen that how to achieve effective welding of water nozzles and liquid cooling plates based on the CMT welding process is a topic worthy of study. Summary of the invention

[0010] In a first aspect of the present invention, in order to solve the above technical problems, the present invention provides a method for welding a water nozzle and a liquid cooling plate in an aluminum alloy battery tray, the method comprising: S1. The welding robot drives the welding gun to perform periodic swinging motion along the weld track of the workpiece to be welded, and the swinging motion path spans across both sides of the weld; S2. Set at least one welding transition point along the weld path to divide the weld into N welding sub-paths. Among them, the welding heat input of the last sub-path in two adjacent welding sub-paths is lower than that of the previous sub-path. S3. During the swing of the welding torch, the position of the tip of the welding torch is detected in real time, where: When the welding torch swings to the first side area, trigger and output the CMT process. When the welding torch swings to the second side area, switch to the pulsed arc process.

[0011] Further, the S2 further includes: When the welding torch passes through the welding transition point, reduce the welding current and / or increase the welding speed according to the serial number of the current welding sub-path, so that the heat input of the last sub-path is reduced by 20%-50%.

[0012] Further, the reduction of the heat input of the last sub-path by 20%-50% is achieved by at least one of the following methods: a. Reduce the wire feeding speed of the CMT process by 10%-30%. b. Reduce the peak current of the pulsed arc process by 50-100 A. c. Increase the welding speed by 15%-40% when the welding torch is located on the last sub-path.

[0013] Further, the first side area corresponds to the area where the liquid cooling plate is located; The second side area corresponds to the area where the water nozzle is located.

[0014] Further, the heat input of the CMT process is 0.8-1.2 kJ / mm; The heat input of the pulsed arc process is 1.8-2.5 kJ / mm.

[0015] Further, the number of welding transition points in the S2 is determined according to the thickness h of the water nozzle: When 5 mm ≤ h < 7 mm, set 1-2 welding transition points; When h ≥ 7 mm, set 3-5 welding transition points, and the distance between adjacent welding transition points is 15%-30% of the total length of the weld.

[0016] In the first aspect of the present invention, a welding system for a water nozzle and a liquid cooling plate in an aluminum alloy battery tray is provided, including: A segmented path planning module that generates welding sub-paths containing welding transition points according to the thickness of the water nozzle; A heat input control module that dynamically adjusts the welding parameters of the welding sub-path by real-time monitoring of the weld temperature; A process switching actuator is used to control the alternating switching of a dual-process welding power source in response to a welding torch position signal.

[0017] Furthermore, the dual process includes a CMT process and a pulsed arc process, where: When the welding torch is located in the area where the liquid cooling plate is located, the CMT process is triggered and output; When the welding torch is located in the area where the water nozzle is located, it is switched to the pulsed arc process.

[0018] Furthermore, at least one welding transition point is provided along the weld path.

[0019] Furthermore, the welding heat input of the last sub-path in two adjacent welding sub-paths is lower than that of the previous sub-path.

[0020] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: By precisely allocating the low-energy CMT process and the high-energy pulsed arc process to the liquid cooling plate and water nozzle areas, the present invention effectively ensures the welding quality and stability of welding joints with large plate thickness differences.

[0021] In addition, for the circular weld formed by the cooperation of the liquid cooling plate and the water nozzle, a welding transition point is introduced, and the welding heat input of the last sub-path is lower than that of the previous sub-path, effectively solving the adverse effect of overheating of the plate parts in the second half of the small-radius circular weld on the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 Schematic diagram of the alternating use of the dual process disclosed in the embodiments of the present invention; Figure 2 Schematic diagram of the welding transition point in the circular weld formed by the cooperation of the liquid cooling plate and the water nozzle disclosed in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Since the heat input of the conventional CMT process is limited and it is only suitable for thin plates with a thickness of less than 3 mm. Therefore, for welded joints with a large difference in welding plate thickness, the present invention adopts the CMT MIX process, that is, the pulsed arc is fused into the traditional CMT process. Please refer to Figure 1 , during welding, the high-energy pulsed arc process and the low-energy CMT process are alternately performed in cycles to precisely control the heat input.

[0026] The present invention aims to provide a welding method for the water nozzle and the liquid cooling plate in an aluminum alloy battery tray, which mainly includes the following steps: Step 1: The welding robot drives the welding torch to perform a periodic swinging motion along the weld track of the workpiece to be welded, and the swinging path straddles both sides of the weld.

[0027] Step 2: Set at least one welding transition point along the weld track to divide the weld into N welding sub-paths. Among them, the welding heat input of the last sub-path in two adjacent welding sub-paths is lower than that of the previous sub-path.

[0028] Step 3: During the swinging of the welding torch, the position of the tip of the welding torch is detected in real time, where: When the welding torch swings to the first side area, the CMT process is triggered and output; When the welding torch swings to the second side area, it is switched to the pulsed arc process.

[0029] Specifically: The first side area corresponds to the area where the liquid cooling plate is located; the second side area corresponds to the area where the water nozzle is located.

[0030] When the welding torch swings to the area where the liquid cooling plate is located, the CMT process is triggered and output, and the heat input of the CMT process is 0.8 - 1.2 kJ / mm.

[0031] When the welding torch swings to the area where the water nozzle is located, it is switched to the pulsed arc process, and the heat input of the pulsed arc process is 1.8 - 2.5 kJ / mm.

[0032] In a further aspect of the present invention, the actions and rhythm of the welding robot are adjusted through a preset program, so that the welding torch makes a periodic swinging motion, and the periodic swinging of the welding torch needs to be combined with the CMT MIX process cycle. That is, when the welding torch swings to one side of the liquid cooling plate (thin plate), the CMT process is output, and when the welding torch swings to one side of the water nozzle (thick plate), the pulsed arc process is output. For welding joints with large thickness differences, different welding heat inputs can be allocated, avoiding the phenomenon of burn-through of the thin plate and poor formation of the welding joint of the thick plate.

[0033] Optionally, a laser displacement sensor is integrated at the end of the welding robot.

[0034] Optionally, a three-dimensional laser scanner can be used to obtain the three-dimensional point cloud data of the welding of the liquid cooling plate and the water nozzle and identify their thickness differences.

[0035] Please refer to Figure 2 , since the weld shape of the water nozzle and the liquid cooling plate is a small-radius circle and the welds are relatively concentrated, when welding the first half of the weld, the un-welded plate in the second half has a very high temperature. If the same welding process parameters are used to weld the second half, it will cause too much heat input to the weld in the second half, resulting in the phenomenon of burn-through of the liquid cooling plate (thin plate).

[0036] For small-radius circular welds, the present invention introduces welding transition points, that is, at least 1 welding transition point can be set in the middle of the weld, dividing the circular weld into N segments, where N is an integer greater than or equal to 2. When the welding torch passes through the welding transition point, the welding current is reduced and / or the welding speed is increased according to the serial number of the current welding sub-path, so that the heat input of the last sub-path is reduced by 20%-50%.

[0037] Optionally, the reduction of the heat input of the last sub-path by 20%-50% is achieved by at least one of the following methods: a. Reducing the wire feeding speed of the CMT process by 10%-30%; b. Reducing the peak current of the pulsed arc process by 50-100 A; c. Increasing the welding speed by 15%-40% when the welding torch is located in the last sub-path.

[0038] In a further aspect of the present invention, the number of welding transition points is mainly determined according to the thickness h of the water nozzle: When 5 mm ≤ h < 7 mm, 1-2 welding transition points are set; When h ≥ 7 mm, 3-5 welding transition points are set, and the spacing between adjacent welding transition points is 15%-30% of the total weld length.

[0039] The present invention also provides a welding system for a water nozzle and a liquid cooling plate in an aluminum alloy battery tray, which mainly includes a segmented path planning module, a heat input control module, and a process switching actuator.

[0040] The segmented path planning module can generate a welding sub-path containing welding transition points according to the thickness of the water nozzle.

[0041] The heat input control module is used to dynamically adjust the welding parameters of the welding sub-path by real-time monitoring of the weld temperature.

[0042] The process switching actuator is used to control the alternating switching of the dual-process welding power supply in response to the welding torch position signal.

[0043] Among them, the dual process includes the CMT process and the pulsed arc process.

[0044] At least one welding transition point is arranged along the weld track, and the welding heat input of the last sub-path in two adjacent welding sub-paths is lower than that of the previous sub-path.

[0045] The present invention proposes a CMT MIX welding process for a water nozzle and a liquid cooling plate of an aluminum alloy battery tray. During the welding process, the high-energy pulsed arc process and the low-energy CMT process are accurately distributed to the water nozzle and the liquid cooling plate through the swing setting, which can ensure the welding quality and stability of the welding joint with a large difference in plate thickness.

[0046] For the circular weld formed by the cooperation of the water nozzle and the liquid cooling plate, the introduction of the welding transition point effectively solves the adverse effect of overheating of the plate in the second half of the small-radius circular weld on the welding quality.

[0047] The present invention fuses the pulsed arc into the traditional CMT process. Compared with the existing laser wire filling welding process, on the premise of effectively ensuring the welding quality, it not only greatly reduces the welding cost, but also improves the production rhythm.

[0048] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for welding a water nozzle and a liquid cooling plate in an aluminum alloy battery tray, characterized in that: The method comprises: S1. The welding robot drives the welding gun to perform periodic swinging motion along the weld track of the workpiece to be welded, and the swinging motion path spans across both sides of the weld; S2, setting at least one welding transition point along the weld trajectory, dividing the weld into N welding sub-paths, wherein the welding heat input of the last sub-path of two adjacent welding sub-paths is lower than the welding heat input of the previous sub-path; S3. During the welding gun swinging process, the position of the welding gun tip is detected in real time, wherein: When the welding gun swings to the first side area, the output CMT process is triggered; When the welding gun is swung to the second side area, the welding gun is switched to a pulse arc process.

2. The welding method of the water nozzle and the liquid cooling plate in the aluminum alloy battery tray according to claim 1 is characterized in that: The S2 further includes: When the welding gun passes through the welding transition point, the welding current is reduced and / or the welding speed is increased according to the sequence number of the current welding sub-path, so that the heat input of the last sub-path is reduced by 20%-50%.

3. The welding method of the water nozzle and the liquid cooling plate in the aluminum alloy battery tray according to claim 2 is characterized in that: The heat input of the last sub-path is reduced by 20%-50% by at least one of the following methods: a. Reduce the wire feeding speed of the CMT process by 10%-30%; b. Reduce the peak current of the pulse arc process by 50-100A; c. When the welding gun is located at the last sub-path, the welding speed is increased by 15%-40%.

4. The method for welding a water nozzle and a liquid cooling plate in an aluminum alloy battery tray according to claim 1, characterized in that: The first side area corresponds to the area where the liquid cooling plate is located; The second side area corresponds to the area where the water nozzle is located.

5. The method for welding a water nozzle and a liquid cooling plate in an aluminum alloy battery tray according to claim 1, characterized in that: The heat input of the CMT process is 0.8-1.2 kJ / mm; The heat input of the pulse arc process is 1.8-2.5 kJ / mm.

6. The method for welding a water nozzle and a liquid cooling plate in an aluminum alloy battery tray according to claim 4, characterized in that: The number of welding transition points in S2 is determined according to the thickness h of the water nozzle: When 5mm≤h<7mm, set 1-2 welding transition points; When h≥7mm, 3-5 welding transition points are set, and the spacing between adjacent welding transition points is 15%-30% of the total length of the weld.

7. A welding system for a water nozzle and a liquid cooling plate in an aluminum alloy battery tray, characterized in that: include: A segmented path planning module generates a welding sub-path containing a welding transition point according to the thickness of the nozzle; A heat input control module dynamically adjusts the welding parameters of the welding subpath by real-time monitoring of the weld temperature; The process switching actuator is used to control the alternating switching of dual process welding power sources in response to a welding gun position signal.

8. The welding system for the water nozzle and the liquid cooling plate in the aluminum alloy battery tray according to claim 7, characterized in that: The dual process includes a CMT process and a pulse arc process, wherein: When the welding gun is located in the area where the liquid cooling plate is located, the CMT process is triggered and output; When the welding gun is in the area of ​​the water nozzle, switch to the pulse arc process.

9. The welding system for the water nozzle and the liquid cooling plate in the aluminum alloy battery tray according to claim 7, characterized in that: At least one welding transition point is arranged along the weld trajectory.

10. The welding system for the water nozzle and the liquid cooling plate in the aluminum alloy battery tray according to claim 7, characterized in that: The welding heat input of the last sub-path in the two adjacent welding sub-paths is lower than the welding heat input of the first sub-path.

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