An adaptive dynamic temperature control and cooling system and its control method for laser molten pools used in joining dissimilar materials

Abstract

This invention discloses an adaptive dynamic temperature control and cooling system and its control method for laser-assisted molten pool joining of dissimilar materials. The system includes: a laser energy input module, a temperature monitoring module, a data acquisition and processing module, an adaptive control module, and a cooling module. The laser energy input module provides the laser beam required for welding and preheating. The temperature monitoring module acquires real-time, non-contact data on the surface temperature of the molten pool and images of the molten pool temperature distribution. The data acquisition and processing module receives the temperature data and temperature distribution images, performs data fusion and processing, and obtains the spatial temperature distribution of the molten pool. The adaptive control module dynamically adjusts the laser power, scanning speed, and path according to the spatial temperature distribution of the molten pool. The cooling module automatically adjusts the cooling gas flow rate or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization. This invention improves weld quality and connection reliability.

Description

Technical Field

[0001] This invention belongs to the field of laser welding technology, and particularly relates to an adaptive dynamic temperature control and cooling system for laser molten pools used in joining dissimilar materials, and its control method. Background Technology

[0002] Laser welding, as a highly efficient and precise joining process, is widely used in high-end equipment manufacturing fields such as automobiles, rail transportation, aerospace, and new energy. In the welding of dissimilar metals (such as aluminum / steel, copper / aluminum, etc.), laser welding has become an important means to improve structural lightweighting and connection strength due to its advantages such as high energy density, concentrated heat input, narrow weld seam, and small heat-affected zone.

[0003] Existing laser welding systems typically employ fixed-parameter laser energy input, meaning that process parameters such as laser power, scanning speed, and focal point position are set before welding based on experiments or experience. Some systems are equipped with basic temperature detection devices (such as single-point infrared thermometers) capable of intermittently and locally monitoring the temperature of the molten pool or weld surface during welding. However, limitations include a small number of temperature measurement points, slow response speed, and deviations from the actual molten pool temperature distribution, making it impossible to accurately reflect the dynamic changes in the instantaneous temperature field of the molten pool. Furthermore, most existing systems are open-loop control systems, lacking practical temperature feedback adjustment mechanisms, resulting in delayed responses to abnormal temperature fluctuations and low control accuracy and welding stability.

[0004] In the process of dissimilar metal laser welding, due to the significant differences in the thermophysical properties (such as melting point, thermal conductivity, coefficient of thermal expansion, etc.) between different materials, the temperature of the molten pool is prone to drastic fluctuations. When the temperature is too high, it can easily lead to an excessively thick intermetallic compound layer, weld porosity, and cracks. When the temperature is too low, it can lead to defects such as poor fusion and incomplete penetration. Traditional cooling methods (such as overall gas coverage or natural cooling after welding) lack precise control over the local temperature of the molten pool, have a slow cooling response, and cannot meet the requirements for fine-tuning the microstructure and properties of the welded joint.

[0005] In recent years, existing technologies have proposed closed-loop temperature control systems for laser welding processes, employing infrared thermometry and optical imaging to achieve real-time monitoring of the molten pool temperature and adjusting the laser power using simple PID algorithms. However, due to the susceptibility of sensors to interference from metal reflection and spatter, the simplistic temperature signal processing methods, and the lack of integrated, efficient local cooling adjustment modules, the actual control effect is limited. Especially under complex operating conditions, existing solutions struggle to simultaneously achieve high-precision dynamic temperature adjustment and coordinated optimization of cooling response, resulting in limited room for improvement in weld quality.

[0006] In summary, existing laser welding temperature control systems generally suffer from the following main shortcomings:

[0007] 1. Temperature monitoring methods are limited, lacking spatial resolution and real-time performance, and cannot obtain complete temperature field information of the molten pool;

[0008] 2. Lack of efficient data fusion and intelligent analysis, resulting in sluggish temperature feedback adjustment response and large fluctuations in the welding process;

[0009] 3. The cooling system is disconnected from the laser energy regulation, making it impossible to achieve dynamic, local, and precise control of the molten pool temperature;

[0010] 4. The adjustment of process parameters relies on manual experience, and the level of intelligence and automation is low, making it difficult to meet the high-quality requirements of high-end manufacturing for the connection of complex dissimilar materials.

[0011] Therefore, there is an urgent need to propose an adaptive dynamic temperature control and cooling system for laser molten pools and its control method for joining dissimilar materials. Summary of the Invention

[0012] To address the aforementioned technical problems, this invention proposes an adaptive dynamic temperature control and cooling system and its control method for laser molten pools used in the joining of dissimilar materials. This system enables real-time monitoring of the welding molten pool temperature on the end face of aluminum-steel dissimilar material gears, intelligent feedback control of laser energy input, and, in conjunction with a high-efficiency cooling module, dynamic adjustment of the molten pool temperature distribution. This effectively suppresses welding defects and improves weld quality and connection reliability.

[0013] To achieve the above objectives, this invention provides an adaptive dynamic temperature control and cooling system for laser molten pools used in joining dissimilar materials, comprising:

[0014] Laser energy input module, temperature monitoring module, data acquisition and processing module, adaptive control module, and cooling module;

[0015] The laser energy input module is used to provide the laser beam required for welding and preheating;

[0016] The temperature monitoring module is used to acquire molten pool surface temperature data and molten pool temperature distribution images in real time without contact.

[0017] The data acquisition and processing module is used to receive temperature data and temperature distribution images, and perform data fusion and processing to obtain the spatial temperature distribution of the molten pool.

[0018] The adaptive control module is used to dynamically adjust the laser power, scanning speed and path according to the spatial temperature distribution of the molten pool;

[0019] The cooling module is used to automatically adjust the cooling gas flow rate or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization.

[0020] On the other hand, to achieve the above objectives, the present invention provides a control method for an adaptive dynamic temperature control and cooling system for laser molten pools used in the joining of dissimilar materials, comprising:

[0021] The laser beam and preheating required for welding are provided through the laser energy input module;

[0022] The temperature monitoring module collects real-time data on the molten pool temperature and temperature distribution.

[0023] The data acquisition and processing module receives temperature data and temperature distribution images, performs data fusion and processing, and obtains the spatial temperature distribution of the molten pool.

[0024] The adaptive control module dynamically adjusts the laser power, scanning speed, and path based on the spatial temperature distribution of the molten pool.

[0025] The cooling module automatically adjusts the cooling gas flow or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization.

[0026] Technical effects of the invention:

[0027] (1) Intelligent fusion of multi-source temperature signals to improve data accuracy and robustness: The data acquisition and processing module is used to fuse different types of temperature signals to achieve complementary and automatic correction of temperature information, which significantly improves the spatial resolution and anti-interference ability of temperature monitoring and ensures the stable operation of the temperature control system.

[0028] (2) Adaptive laser and cooling parameter adjustment, high temperature control accuracy: This invention uses built-in PID control algorithm and fuzzy control algorithm to dynamically adjust the laser energy input (such as power, scanning speed, etc.) and cooling module parameters (such as gas flow rate, cooling intensity) based on the molten pool temperature feedback, so as to achieve high-precision closed-loop control of the molten pool temperature and effectively suppress temperature overshoot, fluctuation and local abnormality in the welding process.

[0029] (3) The cooling system responds quickly and achieves precise local temperature control of the molten pool: The cooling module uses high-flow-rate controllable gas nozzles and / or cooling plates to perform targeted and rapid cooling adjustment of the molten pool area. It can automatically adjust the cooling intensity according to temperature changes to prevent defects such as overheating of the weld and excessive thickness of the intermetallic compound layer, thereby improving the uniformity and density of the weld structure.

[0030] (4) Effectively suppress typical weld defects and improve the quality of dissimilar material connection: Through the coordinated adaptive control of laser energy and cooling system, the present invention can effectively reduce common defects such as porosity, cracks, incomplete penetration and excessive thickness of intermetallic compound layer during the welding process, obtain dense, uniform weld with excellent mechanical properties, and greatly improve the reliability and service life of dissimilar material connection.

[0031] (5) Enhance the automation, intelligence and traceability of the welding process: The system has a human-machine interface, which can realize the visualization setting of process parameters, real-time process monitoring and abnormal alarm, making it convenient for operators to optimize the welding process and track the quality, and significantly improving the automation and intelligence level of laser welding.

[0032] (6) Wide range of applications and high engineering application value:

[0033] This invention is applicable to high-requirement laser welding of various dissimilar materials such as aluminum / steel and copper / aluminum. It is particularly suitable for high-end manufacturing fields such as automobiles, aerospace, rail transportation, and new energy equipment, and has broad engineering application prospects and industrial promotion value.

[0034] In summary, this invention significantly improves the process stability, weld quality, and production automation level of laser welding of dissimilar materials through multi-source temperature monitoring, intelligent data fusion, and adaptive laser energy and cooling parameter control. It has the advantages of strong structural innovation, high control precision, practicality, and significant promotional value. Attached Figure Description

[0035] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0036] Figure 1 This is a schematic diagram of a laser molten pool adaptive dynamic temperature control and cooling system for joining dissimilar materials, according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic flowchart of a control method for an adaptive dynamic temperature control and cooling system for laser molten pools used in joining dissimilar materials, according to an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of a typical cross-sectional structure of a welded joint according to an embodiment of the present invention. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0041] like Figure 1As shown, this embodiment provides an adaptive dynamic temperature control and cooling system for laser molten pools used in joining dissimilar materials, comprising:

[0042] Laser energy input module, temperature monitoring module, data acquisition and processing module, adaptive control module, and cooling module;

[0043] The laser energy input module is used to provide the laser beam required for welding and preheating;

[0044] The temperature monitoring module is used to acquire molten pool surface temperature data and molten pool temperature distribution images in real time without contact.

[0045] The data acquisition and processing module is used to receive temperature data and temperature distribution images, and perform data fusion and processing to obtain the spatial temperature distribution of the molten pool.

[0046] The adaptive control module is used to dynamically adjust the laser power, scanning speed and path according to the spatial temperature distribution of the molten pool;

[0047] The cooling module is used to automatically adjust the cooling gas flow rate or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization.

[0048] Furthermore, the laser energy input module includes a main laser and / or an auxiliary laser;

[0049] The main laser is used to melt dissimilar materials in the welding zone;

[0050] The auxiliary laser is used to locally preheat the steel end.

[0051] Furthermore, the temperature monitoring module includes an infrared thermometer and a high-temperature camera;

[0052] The infrared thermometer is used to acquire the surface temperature of the molten pool in real time;

[0053] The high-temperature camera is used to acquire images of the temperature distribution of the molten pool in real time;

[0054] The infrared thermometer and the high-temperature camera are respectively arranged above the welding area and are communicatively connected to the data acquisition and processing module.

[0055] Furthermore, the data acquisition and processing module includes an industrial PC or an embedded controller;

[0056] The industrial PC is used to synchronously acquire and fuse the temperature data and temperature distribution images, and output the molten pool temperature field in real time.

[0057] The embedded controller is used for high-frequency data acquisition and multi-source temperature signal fusion, wherein the high frequency is not less than 200Hz.

[0058] Furthermore, the adaptive control module includes a PID controller combined with a fuzzy control algorithm. The inputs to the fuzzy control algorithm are the molten pool temperature deviation ΔT and the temperature gradient. By establishing a fuzzy rule base, the PID parameter correction amount and laser power coefficient are output, and the main laser power, scanning speed and auxiliary laser preheating power are dynamically adjusted by combining the relationship between scanning speed and real-time temperature.

[0059] Furthermore, the cooling module includes a high-flow-rate controllable gas nozzle and / or a cooling plate. The high-flow-rate controllable gas nozzle is installed on the welding workbench to provide localized forced convection cooling, enhance heat exchange around the molten pool, and the gas flow rate is automatically adjusted by an adaptive control module. The cooling plate is located below the forming substrate and controls the temperature of the forming zone. The cooling intensity is automatically adjusted by the adaptive control module.

[0060] Furthermore, the system also includes a human-computer interaction module for parameter setting, process monitoring, and alarm functions.

[0061] like Figure 2 As shown, this embodiment also provides a control method for a laser molten pool adaptive dynamic temperature control and cooling system applied to the joining of dissimilar materials, including:

[0062] The laser beam and preheating required for welding are provided through the laser energy input module;

[0063] The temperature monitoring module collects real-time data on the molten pool temperature and temperature distribution.

[0064] The data acquisition and processing module receives temperature data and temperature distribution images, performs data fusion and processing, and obtains the spatial temperature distribution of the molten pool.

[0065] The adaptive control module dynamically adjusts the laser power, scanning speed, and path based on the spatial temperature distribution of the molten pool.

[0066] The cooling module automatically adjusts the cooling gas flow or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization.

[0067] Specifically, the adaptive control module compares the collected temperature information with the preset temperature threshold and uses PID and / or fuzzy control algorithms to automatically adjust the laser energy input (including main laser power, auxiliary laser power, scanning speed, etc.) so that the molten pool temperature is always kept within the optimal welding window.

[0068] When the temperature of the molten pool is higher than the set upper limit, the control system automatically starts the cooling module to adjust the gas jet flow rate or the temperature of the cooling plate to achieve local rapid cooling and avoid overheating; when the temperature is lower than the lower limit, the cooling intensity is appropriately reduced to prevent excessive cooling from causing incomplete penetration.

[0069] The system monitors abnormal temperature fluctuations during the process and issues real-time alarms through the human-machine interface, prompting operators to optimize process parameters.

[0070] Example 1: Temperature control and cooling application in laser lap welding of dissimilar metals such as aluminum and steel

[0071] In this embodiment, the laser molten pool adaptive dynamic temperature control and cooling system of the present invention is used to perform laser lap welding on an aluminum alloy plate with a thickness of 2mm and a galvanized steel plate with a thickness of 2mm. The specific system configuration is as follows:

[0072] Laser energy input module: A 1064nm fiber laser with a power range of 4kW is selected, and an 808nm auxiliary laser with an auxiliary power of 2kW is provided. The main laser beam is used to melt the joint area, and the auxiliary laser beam is used to locally preheat the steel end.

[0073] Temperature monitoring module: An infrared thermometer with a response frequency higher than 100Hz and an industrial high-temperature camera suitable for high-temperature scenarios are set in the welding area to acquire images of the surface temperature of the molten pool and the temperature distribution of the area in real time, respectively.

[0074] Data acquisition and processing module: It adopts an industrial PC and integrates a multi-channel data acquisition card to synchronously acquire and fuse infrared temperature measurement and camera signals, and output the molten pool temperature field in real time.

[0075] Adaptive control module: It incorporates a temperature-feedback-based PID controller and combines it with a fuzzy control algorithm to dynamically adjust the main laser power, scanning speed, and auxiliary laser preheating power. The target temperature window is set to 1350–1450℃.

[0076] Cooling module: Argon gas jet cooling nozzles are arranged on both sides of the weld pool, with the gas flow rate automatically adjusted within the range of 10–50 L / min. The gas flow rate is automatically increased when the temperature exceeds the preset upper limit and decreased when the temperature falls below the lower limit.

[0077] Human-machine interface: Supports process parameter setting, real-time temperature curve display and over-temperature alarm.

[0078] Actual welding verification has shown that dynamic and stable control of the molten pool temperature can be achieved continuously, the thickness of the intermetallic compound layer in the weld zone is stable at 8-12 μm, no defects such as porosity or cracks were found, the tensile and shear strength of the welded joint reaches more than 85% of the strength of the base material, and the process is stable and reliable.

[0079] Example 2: Multi-point temperature feedback adaptive control for copper / aluminum dissimilar metal spot welding

[0080] In this embodiment, the system of this invention is used for temperature control and cooling of the laser spot welding connection of the copper / aluminum tabs in the power battery of new energy vehicles. The main parameters are as follows:

[0081] 1. Laser energy input module: 1.5kW fiber laser with wavelength of 1064nm, equipped with an automatic focusing system.

[0082] 2. Temperature monitoring module: Two infrared thermometers (detecting different points) and a high-temperature camera are respectively arranged above the welding head to realize real-time temperature acquisition at multiple points.

[0083] 3. Data Acquisition and Processing Module: An embedded industrial computer is used for high-frequency (200Hz) data acquisition and multi-source temperature signal fusion.

[0084] 4. Adaptive Control Module: Employs a fuzzy control algorithm to adjust the laser single-pulse energy, spot welding duration, and pulse interval in real time. The temperature window is set to 1050–1150℃ to prevent excessive copper volatilization and aluminum melt-through.

[0085] 5. Cooling module: It adopts a miniature gas nozzle, the gas type is high-purity helium, and the flow rate is dynamically controlled within the range of 5 to 30 L / min.

[0086] 6. Human-computer interaction interface: Supports querying of single-point and multi-point temperature history curves and abnormal alarms.

[0087] Experimental results show that the system of the present invention can control the temperature fluctuation of the spot welding pool within ±30℃, effectively reduce spatter and cold solder joints, and produce low resistance and excellent mechanical properties of the weld joints, making it suitable for mass automated production.

[0088] Example 3: Online quality monitoring and intelligent feedback adjustment of laser welds

[0089] like Figure 3 As shown, this embodiment addresses the longitudinal seam welding of aluminum / steel in high-end equipment manufacturing, utilizing the system of this invention to achieve online monitoring and intelligent control of weld quality.

[0090] Laser energy input module: main laser power 3.5kW, scanning speed 12mm / s.

[0091] Temperature monitoring module: A high-temperature camera is set up to collect the weld width and molten pool temperature distribution in real time; infrared temperature measurement data is collected simultaneously.

[0092] Data acquisition and processing module: Analyzes weld temperature gradient and width changes in real time and compares them with the ideal temperature field in the process database.

[0093] Adaptive control module: When an abnormal local temperature is detected in the weld (such as local overheating or undercooling), the laser path (such as oscillation amplitude), power and cooling airflow direction are automatically adjusted to achieve uniformity of the weld temperature field.

[0094] Cooling module: Employs multi-channel gas jets, with independently adjustable airflow direction and flow rate.

[0095] Human-machine interface: Real-time display of weld thermal images, process alarm prompts, and parameter adjustment suggestions.

[0096] Practical application results: The weld temperature distribution is uniform during the welding process, with no lack of fusion or spatter. The weld structure is dense, the intermetallic compound layer thickness is uniform, the welding quality is stable, and the system has a high degree of intelligence and adaptability.

[0097] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An adaptive dynamic temperature control and cooling system for laser molten pools used in joining dissimilar materials, characterized in that, include: Laser energy input module, temperature monitoring module, data acquisition and processing module, adaptive control module, and cooling module; The laser energy input module is used to provide the laser beam required for welding and preheating; The temperature monitoring module is used to acquire molten pool surface temperature data and molten pool temperature distribution images in real time without contact. The data acquisition and processing module is used to receive temperature data and temperature distribution images, and perform data fusion and processing to obtain the spatial temperature distribution of the molten pool. The adaptive control module is used to dynamically adjust the laser power, scanning speed and path according to the spatial temperature distribution of the molten pool; The cooling module is used to automatically adjust the cooling gas flow rate or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization. The laser energy input module includes a main laser and / or an auxiliary laser; The main laser is used to melt dissimilar materials in the welding zone; The auxiliary laser is used to locally preheat the steel end; The temperature monitoring module includes an infrared thermometer and a high-temperature camera; The infrared thermometer is used to acquire the surface temperature of the molten pool in real time; The high-temperature camera is used to acquire images of the temperature distribution of the molten pool in real time; The infrared thermometer and the high-temperature camera are respectively arranged above the welding area and are communicatively connected to the data acquisition and processing module. The data acquisition and processing module includes an industrial PC or an embedded controller; The industrial PC is used to synchronously acquire and fuse the temperature data and temperature distribution images, and output the molten pool temperature field in real time. The embedded controller is used for high-frequency data acquisition and multi-source temperature signal fusion, wherein the high frequency is not less than 200 Hz. The adaptive control module includes a PID controller, combined with a fuzzy control algorithm. The inputs of the fuzzy control algorithm are the molten pool temperature deviation ΔT and the temperature gradient ∇T. The PID parameter correction and laser power coefficient are output through the established fuzzy rule base. The main laser power, scanning speed and auxiliary laser preheating power are dynamically adjusted by combining the relationship between scanning speed and real-time temperature. The cooling module includes a high-flow-rate controllable gas nozzle and / or a cooling plate. The high-flow-rate controllable gas nozzle is installed on the welding workbench to provide localized forced convection cooling, enhance heat exchange around the molten pool, and the gas flow rate is automatically adjusted by an adaptive control module. The cooling plate is located below the forming substrate and controls the temperature of the forming zone. The cooling intensity is automatically adjusted by the adaptive control module. The system also includes a human-computer interaction module for parameter setting, process monitoring, and alarms.

2. A control method for an adaptive dynamic temperature control and cooling system for laser molten pools applied to the joining of dissimilar materials according to claim 1, characterized in that, include: The laser beam and preheating required for welding are provided through the laser energy input module; The temperature monitoring module collects real-time data on the molten pool temperature and temperature distribution. The data acquisition and processing module receives temperature data and temperature distribution images, performs data fusion and processing, and obtains the spatial temperature distribution of the molten pool. The adaptive control module dynamically adjusts the laser power, scanning speed, and path based on the spatial temperature distribution of the molten pool. The cooling module automatically adjusts the cooling gas flow or cooling plate temperature according to the molten pool temperature to achieve rapid cooling and temperature stabilization.

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