Laser welding process for refrigerator liner seam

Abstract

The invention discloses a laser welding process for refrigerator liner joints. The laser welding process comprises the following steps that a composite aluminum plate is pretreated and then put into a laser welding box; preheating the peripheral area of the to-be-welded joint; laser continuous welding is conducted on the to-be-welded joint, and in the welding process, generated smoke dust is synchronously sucked away; and after laser continuous welding is completed, the joint area is scoured through argon, and the temperature of the joint area is slowly cooled to the room temperature. In the process that a composite aluminum plate with the thickness of silicon nitride and aluminum being 1-3 mm is subjected to seam welding to form the refrigerator inner container, pretreatment, seam preheating, welding environment control, strict control over laser welding parameters, real-time smoke extraction and slow cooling means after welding are conducted in sequence. The welding quality and efficiency can be ensured, meanwhile, the existence time of a molten pool can be prolonged, hydrogen has more time to escape from the molten pool, the risk that air holes are formed in the solidification process of the molten pool is reduced, the porosity of a seam after welding is reduced, and the hardness of the seam is improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser welding, and in particular to a laser welding process for a seam of a refrigerator liner. Background Art

[0002] The refrigerator liner is the core structural component inside the refrigerator. The material selection and manufacturing process are directly related to the refrigerator's thermal insulation performance, durability and overall quality. Composite aluminum materials are used to prepare refrigerator liner based on its good thermal conductivity, lightweight characteristics and relatively high corrosion resistance. Composite aluminum can significantly improve the material's strength, hardness and wear resistance by uniformly embedding or coating other reinforcing materials (such as silicon carbide SiC, aluminum oxide Al2O3, etc.) in the aluminum matrix, thereby extending the service life of the refrigerator liner.

[0003] However, while these reinforced particles in composite aluminum bring performance improvements, they also bring challenges to the laser welding process. These hard particles are not easy to melt during the welding process, and due to the difference in thermal expansion coefficient between them and the aluminum matrix, they easily cause stress concentration in the welding area, which in turn causes the formation of cracks or pores. These defects not only affect the strength and sealing of the weld, but may also become potential leakage points during the future use of the refrigerator liner, affecting the insulation effect and safety.

[0004] Therefore, it is necessary to provide a laser welding process for the seams of refrigerator liner to solve the above technical problems. Summary of the invention

[0005] The invention overcomes the shortcomings of the prior art and provides a laser welding process for the seams of refrigerator liner.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a laser welding process for the seam of the refrigerator liner, comprising the following steps: Step S1, after pre-processing the composite aluminum plate, put it into a laser welding box, position the two composite aluminum plates so that a seam to be welded extending along the welding direction is formed between the two composite aluminum plates, and the seam to be welded is automatically identified by using visual positioning technology; Step S2, based on the recognition result of step S1, preheating the surrounding area of ​​the weld to be welded, controlling the temperature at 150-200° C., and performing laser spot welding at multiple equidistant points on the weld to be welded after the preheating temperature reaches the standard, keeping the weld to be welded relatively fixed; Step S3, performing laser continuous welding on the seam to be welded, the process parameters of the laser continuous welding are: laser pulse peak power 1350-1700W, pulse waveform is rectangular wave, pulse width 3.5-4ms, welding speed 100mm / min-128mm / min, defocus amount -1mm--0.5mm, and during the welding process, the generated smoke is synchronously extracted; Step S4: After the laser continuous welding is completed, the joint area is flushed with argon gas to slowly cool the temperature of the joint area to room temperature, thereby completing the welding of the refrigerator liner joint.

[0007] In a preferred embodiment of the present invention, the composite aluminum plate is a composite material of silicon nitride and aluminum, and has a thickness of 1 to 3 mm.

[0008] In a preferred embodiment of the present invention, in step S2, preheating the surrounding area of ​​the weld to be welded specifically includes the following steps: Step S21, based on the recognition result of the weld to be welded in step S1, move the ceramic heater closer to the composite aluminum plate from the bottom of the composite aluminum plate until it contacts the bottom surface of the composite aluminum plate, and the position of the ceramic heater is directly above the weld to be welded area; Step S22, start the ceramic heater to heat the seam area to be welded of the composite aluminum plate, detect the temperature of the seam area to be welded in real time, stop heating after the temperature of each location in the seam area to be welded reaches 150-200°C, and recycle the ceramic heater.

[0009] In a preferred embodiment of the present invention, in step S4, the cooling method of the joint area comprises the following steps: Step S41, arranging a number of infrared thermometers evenly distributed along the length direction of the joint, monitoring the temperature of the joint area in real time, and generating a joint temperature distribution curve based on the collected temperatures at different positions in the joint area; Step S42, arranging a plurality of nozzles above the joint area, each nozzle being provided with a flow control valve, the nozzle being connected to an argon gas supply unit through a pipeline, and spraying argon gas toward the joint area; Step S43, establishing a cooling control strategy, dynamically adjusting the argon flow rates of nozzles at different positions according to the joint temperature distribution curve output by the temperature monitoring unit to achieve the same cooling efficiency.

[0010] In a preferred embodiment of the present invention, in step S41, the generation of the seam temperature distribution curve specifically includes the following steps: Step S411, dividing the measuring point coordinates for each infrared thermometer along the length direction of the joint, which is the X-axis coordinate in the joint temperature distribution curve; Step S412, arranging the seam temperature data collected by each infrared thermometer according to the corresponding measuring point coordinates, and performing interpolation processing to estimate the temperature value of the unmeasured point, that is, the Y-axis coordinate in the seam temperature distribution curve; Step S413, the temperature data after interpolation processing are sequentially connected using a curve according to the order of the measuring point coordinates to obtain a joint temperature distribution curve, where the X-axis represents the position in the length direction of the joint, and the Y-axis represents the temperature value.

[0011] In a preferred embodiment of the present invention, in step S42, the establishment of the cooling control strategy includes the following steps: Step S421: Determine the final target temperature of the joint after cooling based on the thickness, material and maximum temperature reached during welding of the composite aluminum plate. 30~40℃, and preset cooling rate control target ; Step S422: Divide the joint temperature distribution curve into several cooling sub-areas according to the nozzle position , for each cooling sub-area , calculate the average temperature ,in The cooling sub-area The number of measuring points within Step S423: Calculate each cooling sub-area Argon flow rate of inner nozzle , where k is the proportionality constant, For cooling time, ; In a preferred embodiment of the present invention, the determination of the proportional constant k comprises the following steps: Step S434: Based on prior experience, different argon flow rates are preset, and experiments are conducted under different initial temperatures and environmental conditions to determine the relationship between the argon flow rate and the temperature reached. Required cooling time The experimental environment conditions are consistent with the actual welding process; specifically, prior experience refers to literature, experience, etc., and the experiment can be carried out based on the argon flow rate used in previous processing as the initial parameter; Step S435: Establish a machine learning model based on the experimental data of step four to describe the relationship between argon flow rate, cooling time, temperature change and cooling rate, that is, the value of the proportional constant k; the machine learning model is constructed using a machine learning algorithm, and the machine learning model is iteratively optimized according to the difference between the prediction of the machine learning model and the actual cooling effect.

[0012] In a preferred embodiment of the present invention, the preprocessing in step S1 specifically includes the following steps: Step S11, mechanically grinding the butt weld area of ​​the composite aluminum plate until the weld area reveals a metallic luster; Step S12, using acetone and anhydrous ethanol to clean the composite aluminum plate in sequence, wiping the surface of the composite aluminum plate with dust-free paper, and then blowing the surface of the composite aluminum plate dry with argon gas; Step S13, placing the composite aluminum plate in an oven for vacuum baking for 1 to 3 hours, the baking temperature is 100 to 140° C., and the vacuum degree is 9 to 14 Pa.

[0013] In a preferred embodiment of the present invention, the laser welding box is filled with argon gas, and the water and oxygen contents are both below 20 PPM; the laser welding box comprises: a box body, a workbench arranged in the center of the box body, a laser welding system and a dust and fume exhaust system arranged inside the box body; The workbench is provided with a clamping mechanism for positioning the two composite aluminum plates; The laser welding system comprises: a welding head, a first mechanical arm, a second mechanical arm, a three-dimensional camera and a welding control module; the first mechanical arm and the second mechanical arm both have a plurality of freely movable joints and are arranged at the upper position of the inner wall of the box body; wherein the welding head is arranged at the end of the first mechanical arm, and is used for laser welding the seams to be welded of the two composite aluminum plates; the three-dimensional camera is arranged at the end of the second mechanical arm, and is used for collecting images of the seams to be welded of the two composite aluminum plates, the working path of the welding head and real-time working images; The welding control module is used to drive the welding head and the three-dimensional camera to work, and to determine the spot welding position information and the welding path information according to the image of the seam to be welded acquired by the three-dimensional camera based on the visual positioning technology, and then feed back the information to the first robotic arm, so as to control the first robotic arm to adjust its posture in real time, drive the welding head to move along the spot welding position information and the welding path information, and complete the laser spot welding and laser continuous welding of the seam to be welded.

[0014] In a preferred embodiment of the present invention, in step S3, the dust generated during welding is extracted using the dust suction and fume exhaust system; The dust collection and smoke exhaust system comprises: a mounting frame, an exhaust module arranged on the mounting frame, and an automatic adjustment module; The exhaust module includes: a fan arranged outside the box, an air duct arranged at the output end of the fan, and an exhaust head arranged at the other end of the air duct; the exhaust head is connected to the end of the first mechanical arm through the mounting frame to extract smoke and dust generated by laser welding in real time; The automatic adjustment module comprises: Smoke monitoring unit, which uses visual technology to obtain smoke concentration and distribution; An air volume regulating unit, which sets a plurality of air volume gears based on smoke concentration and fan operating power, and adjusts the fan operating power in real time according to the smoke concentration obtained by the smoke monitoring unit; The angle adjustment mechanism adjusts the angle of the exhaust head in real time according to the distribution area of ​​the smoke in the space output by the smoke monitoring unit; specifically, the smoke center is calculated according to the distribution area of ​​the smoke in the space, and the center of the exhaust head is adjusted to align with the smoke center.

[0015] In a preferred embodiment of the present invention, the smoke monitoring unit uses visual technology to obtain the concentration and distribution of smoke, which specifically includes the following steps: Step 1: extracting smoke and dust images based on the real-time working images collected by the three-dimensional camera, and preprocessing the images, wherein the preprocessing includes operations such as denoising and contrast enhancement; Step 2: Analyze the smoke image through image processing technology to obtain the concentration and distribution area of ​​the smoke; specifically, first use image segmentation technology, preferably use edge detection method to separate the smoke area from the image background, and accurately define the smoke area; use pixel value and grayscale parameters to quantitatively analyze the smoke area to estimate the concentration of the smoke; combine the depth information of the three-dimensional camera to construct a three-dimensional distribution model of the smoke and obtain the distribution area of ​​the smoke in space.

[0016] In a preferred embodiment of the present invention, a filter assembly is further provided between the fan and the air duct for filtering smoke and dust; the filter assembly comprises a primary filter layer, a medium filter layer and a high efficiency filter layer which are stacked.

[0017] In a preferred embodiment of the present invention, the process parameters of the laser continuous welding are: laser pulse peak power 1450~1620W, pulse width 3.5~4ms, welding speed 110mm / min~128mm / min, defocus -1mm~-0.5mm.

[0018] The present invention solves the defects existing in the background technology and has the following beneficial effects: (1) The present invention provides a laser welding process for the seams of refrigerator liner. In the process of seam welding of composite aluminum plates of silicon nitride and aluminum with a thickness of 1 to 3 mm to form a refrigerator liner, pretreatment, seam preheating, welding environment control, strict control of laser welding parameters, real-time extraction of smoke and dust, and slow cooling after welding are performed in sequence, which can ensure the quality and efficiency of welding while extending the existence time of the molten pool, so that hydrogen has more time to escape from the molten pool, reduce the risk of pores formed during the solidification process of the molten pool, reduce the porosity of the seam after welding, and thus improve the hardness of the seam. Compared with the prior art, the present invention solves the problem that the reinforced particles in the composite aluminum cause cracks or pores to easily form during welding, thereby increasing the difficulty of welding.

[0019] (2) The present invention provides a laser welding process for the seams of refrigerator liner, and the process parameters for controlling the laser continuous welding are: laser pulse peak power 1350-1700W, pulse waveform is rectangular wave, pulse width 3.5-4ms, welding speed 100mm / min-128mm / min, defocus amount -1mm--0.5mm. When the seam welding of composite aluminum plates with a thickness of 1-3mm is performed, by controlling the combination of laser continuous welding process parameters within the above range, it is possible to ensure the welding quality and efficiency while extending the existence time of the molten pool, so that hydrogen has more time to escape from the molten pool, and reduce the risk of pores forming during the solidification of the molten pool.

[0020] (3) The present invention adopts a preheating mechanism and a controllable slow cooling strategy during laser welding, which significantly reduces the stress concentration and structural deformation generated during the welding process, thereby optimizing the microstructure and macroscopic mechanical properties of the welded joint. Specifically, in the preparation stage before welding of the composite aluminum plate, precise heating of the area surrounding the weld is implemented to achieve a uniform preheating effect before welding, effectively reducing the thermal stress accumulation and structural deformation caused by the temperature gradient during welding. After the joint welding is completed, according to the preset cooling rate target, fine cooling process management is performed to avoid the phenomenon of insufficient solidification time of the molten pool due to excessively fast cooling speed, thereby hindering the effective escape of hydrogen. At the same time, through the precise regulation of the argon flow rate, uniform and stable control of the cooling rate of each area of ​​the joint is achieved, ensuring the balance and controllability of the cooling process.

[0021] (4) The present invention provides a laser welding box, in which the design of the heating module can heat the welding seam area and its periphery in advance, so that the entire welding area reaches a relatively uniform temperature state before welding, thereby effectively reducing the stress and deformation caused by temperature difference during the welding process, and the design of the lifting unit can lift the ceramic heater in the preheating step to heat the welding seam area and retract it after the temperature reaches the standard, thereby avoiding the ceramic heater always being in contact with the composite aluminum plate during the welding process, causing damage to the ceramic heater.

[0022] (5) The present invention provides a laser welding box, which is provided with a dust suction and exhaust system to extract the smoke generated during the welding process. Through the coordinated work of the smoke monitoring unit, the air volume adjustment unit and the angle adjustment mechanism, real-time monitoring of the smoke concentration and distribution and automatic adjustment of the exhaust system are achieved, so that the exhaust head can be accurately aimed at the center of the smoke, thereby improving the smoke capture efficiency and extracting the smoke generated during the laser welding process in real time, effectively avoiding the influence of smoke on the laser focusing and penetration ability, and preventing the smoke from absorbing the laser beam energy and causing the welding power to decrease, thereby ensuring the welding depth and weld quality, and improving the overall quality of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. Figure 1 This is a process flow chart of laser welding for refrigerator liner seams according to a preferred embodiment of the present invention; Figure 2 1 is a graph showing the porosity test results of the embodiments of the present invention and the comparative examples; Figure 3 It is a hardness test result diagram of the preferred embodiment and the comparative example of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0028] like Figure 1 As shown, the present invention provides a laser welding process for the seam of a refrigerator liner, comprising the following steps: S1. After pre-treatment, the composite aluminum plate is placed in a laser welding box, two composite aluminum plates are positioned so that a seam to be welded extending along the welding direction is formed between the two composite aluminum plates, and the seam to be welded is automatically identified using visual positioning technology; S2. Based on the recognition result of step S1, the surrounding area of ​​the weld to be welded is preheated, and the temperature is controlled at 150-200° C. After the preheating temperature reaches the standard, laser spot welding is performed on the weld to be welded at multiple positions at equal distances to keep the weld to be welded relatively fixed; S3. The seam to be welded is subjected to laser continuous welding. The process parameters of laser continuous welding are: laser pulse peak power 1350-1700W, pulse waveform is rectangular wave, pulse width 3.5-4ms, welding speed 100mm / min-128mm / min, defocusing amount -1mm--0.5mm. During the welding process, the smoke generated is extracted synchronously; S4. After the laser continuous welding is completed, the joint area is flushed with argon gas to slowly cool the temperature of the joint area to room temperature to complete the welding of the refrigerator liner joint.

[0029] The seam welding process involved in the present invention can be applied to a variety of composite aluminum plate structures. Specifically, these structures include but are not limited to: a seam formed by directly butting two rectangular composite aluminum plates, an L-shaped structure formed by a composite aluminum plate after a bending process, and further, a complex seam formed by butting the edges of two L-shaped structures. The purpose is to efficiently and stably combine two or more composite aluminum plates through the precise butt joint and seam welding technology of the above structure to construct the key component of the refrigerator liner.

[0030] The preprocessing in step S1 specifically includes the following steps: S11. Mechanically grind the butt weld area of ​​the composite aluminum plate until the weld area reveals a metallic luster; specifically, the mechanically grinded area is within an area 20 mm around the weld to be welded, and a high-precision grinding wheel or abrasive belt is used for grinding until the surface roughness reaches Ra0.8um or less, which can significantly improve the strength and sealing of the weld joint.

[0031] S12. Use acetone and anhydrous ethanol to clean the composite aluminum plate in turn, wipe the surface of the composite aluminum plate with dust-free paper, and then blow dry the surface of the composite aluminum plate with argon gas; specifically, further purify the surface of the composite aluminum plate through chemical cleaning. Acetone, as an organic solvent, can effectively remove residual grease and organic pollutants, while anhydrous ethanol is used to remove acetone residues and possible moisture to ensure absolute cleanliness of the surface. In this step, use dust-free paper to wipe gently to avoid scratching the surface, and then use high-purity argon gas to blow dry to ensure that there is no residual liquid affecting the welding quality. The strict cleaning process performed in this step can reduce the welding defect rate by about 30%.

[0032] S13. Place the composite aluminum plate in an oven for vacuum baking for 1 to 3 hours at a baking temperature of 100 to 140°C and a vacuum degree of 9 to 14 Pa. Place the composite aluminum plate in an oven with set temperature and vacuum degree to remove moisture, volatile gases and residual stress inside the material by heating, which helps to reduce pore formation during welding and improve the density and stability of the welded joint.

[0033] Through the above-mentioned pretreatment steps, mechanical grinding, chemical cleaning and drying, and vacuum baking are carried out in sequence, which lays a solid foundation for the subsequent laser seam welding, ensuring the high-quality welding of the refrigerator liner seams, thereby improving the overall performance and service life of the product.

[0034] In step S2, the area around the weld to be welded is preheated, which specifically includes the following steps: Step S21, based on the recognition result of the weld to be welded in step S1, move the ceramic heater closer to the composite aluminum plate from the bottom of the composite aluminum plate until it contacts the bottom surface of the composite aluminum plate, and the position of the ceramic heater is directly above the weld to be welded area; Step S22, start the ceramic heater to heat the seam area to be welded of the composite aluminum plate, detect the temperature of the seam area to be welded in real time, stop heating after the temperature of each location in the seam area to be welded reaches 150-200°C, and recycle the ceramic heater.

[0035] By setting the preheating step, the welding seam area and its surroundings can be heated in advance, so that the entire welding area reaches a relatively uniform temperature state before welding, thereby effectively reducing the stress and deformation caused by temperature difference during welding.

[0036] In step S4, the cooling method of the joint area includes the following steps: Step S41, arrange a number of infrared thermometers evenly distributed along the length direction of the joint, monitor the temperature of the joint area in real time, and generate a joint temperature distribution curve based on the collected temperatures at different positions in the joint area.

[0037] In step S41, the generation of the joint temperature distribution curve specifically includes the following steps: Step S411, dividing the measuring point coordinates for each infrared thermometer along the length direction of the joint, which is the X-axis coordinate in the joint temperature distribution curve.

[0038] Step S412: Arrange the joint temperature data collected by each infrared thermometer according to the corresponding measuring point coordinates, and perform interpolation processing to estimate the temperature value of the unmeasured point, that is, the Y-axis coordinate in the joint temperature distribution curve.

[0039] Step S413, the temperature data after interpolation processing are sequentially connected using a curve according to the order of the measuring point coordinates to obtain a joint temperature distribution curve, where the X-axis represents the position in the length direction of the joint, and the Y-axis represents the temperature value.

[0040] Through the above steps, the real-time temperature distribution of the joint area can be obtained, which provides data support for the cooling of the joint after welding is completed and accurately controls the cooling process of the entire welding joint.

[0041] Step S42, arranging a plurality of nozzles above the joint area, each nozzle being provided with a flow control valve, and the nozzle being connected to an argon supply unit through a pipeline to spray argon gas toward the joint area.

[0042] Step S43, establishing a cooling control strategy, dynamically adjusting the argon flow rates of nozzles at different positions according to the joint temperature distribution curve output by the temperature monitoring unit to achieve the same cooling efficiency.

[0043] In step S43, the establishment of the cooling control strategy includes the following steps: Step S431: Determine the final target temperature of the joint after cooling based on the thickness, material and maximum temperature reached during welding of the composite aluminum plate. 30~40℃, and preset cooling rate control target ; The cooling rate control target The setting is based on the premise of ensuring welding quality. By controlling the cooling rate, the closing time of the molten pool is delayed to allow hydrogen as much time as possible to overflow from the molten pool.

[0044] Step S432: Divide the joint temperature distribution curve into several cooling sub-areas according to the nozzle position , for each cooling sub-area , calculate the average temperature ,in The cooling sub-area The number of measurement points within.

[0045] Furthermore, the cooling sub-area The division is based on the X-axis coordinate.

[0046] Step S433: Calculate each cooling sub-area Argon flow rate of inner nozzle , where k is the proportionality constant, For cooling time, , the flow Applied to the opening control of flow control valve.

[0047] Further, the determination of the proportional constant k includes the following steps: Step S434: Based on prior experience, different argon flow rates are preset, and experiments are conducted under different initial temperatures and environmental conditions to determine the relationship between the argon flow rate and the temperature reached. Required cooling time The experimental environment conditions are consistent with the actual welding process; specifically, prior experience refers to literature, experience, etc., and the experiment can be carried out based on the argon flow rate used in previous processing as the initial parameter.

[0048] Step S435: Establish a machine learning model based on the experimental data of step four to describe the relationship between argon flow rate, cooling time, temperature change and cooling rate, that is, the value of the proportional constant k; the machine learning model is constructed using a machine learning algorithm, and the machine learning model is iteratively optimized according to the difference between the prediction of the machine learning model and the actual cooling effect.

[0049] Furthermore, the cooling rate control target Is a range value, specifically, controls the cooling rate Within a range of + / - 5%.

[0050] By setting the above cooling control strategy, different positions of the welding area can be evenly cooled in laser seam welding. Even if the temperatures at different positions on the welding area are different, a uniform cooling rate can be achieved, thereby reducing welding stress and deformation and improving the microstructure and macroscopic properties of the welded joint.

[0051] The preheating and cooling system of the present invention adopts a preheating mechanism and a controllable slow cooling strategy, which significantly reduces the stress concentration and structural deformation generated during the welding process, thereby optimizing the microstructure and macroscopic mechanical properties of the welded joint. Specifically, in the preparation stage before welding of the composite aluminum plate, precise heating of the area surrounding the weld is implemented to achieve a uniform preheating effect before welding, effectively reducing the thermal stress accumulation and structural deformation caused by the temperature gradient during welding.

[0052] After the seam welding is completed, according to the preset cooling rate target, the fine cooling process management is performed to avoid the phenomenon that the molten pool solidification time is insufficient due to excessive cooling speed, which in turn hinders the effective escape of hydrogen. At the same time, through the precise control of the argon flow rate, the cooling rate of each area of ​​the seam is uniformly and stably controlled, ensuring the balance and controllability of the cooling process.

[0053] In summary, by integrating preheating and slow cooling technology, the present invention significantly reduces the diffusion efficiency and release amount of hydrogen during the welding process of silicon nitride and aluminum composite aluminum plates, thereby effectively reducing the risk of welding pore formation and improving the overall quality and reliability of the welded joint.

[0054] The laser welding box in this embodiment is filled with argon gas, and the water and oxygen contents are both below 20 PPM. The laser welding box specifically includes: a box body, a workbench arranged in the center of the box body, a laser welding system and a dust suction and fume exhaust system arranged inside the box body.

[0055] The box body is made of high-strength, corrosion-resistant metal material, preferably stainless steel. The box body is designed to be sealed and is equipped with a sealable loading and unloading door and an observation window. The loading and unloading door is used for loading and unloading of composite aluminum plates, and the observation window is made of explosion-proof glass to facilitate observation of the welding process without affecting the internal environment.

[0056] A clamping mechanism is provided on the workbench to position the two composite aluminum plates so that a welding seam extending along the welding direction is formed between the two composite aluminum plates, and to fix them so that their position does not change during the welding process. The specific structure of the clamping mechanism is not limited here, as long as the clamping effect can be achieved.

[0057] The laser welding system includes: a welding head, a first mechanical arm, a second mechanical arm, a three-dimensional camera and a welding control module; the first mechanical arm and the second mechanical arm both have multiple freely movable joints and are arranged at the upper position of the inner wall of the box. Among them, the welding head is arranged at the end of the first mechanical arm, and is used to laser weld the seams to be welded of the two composite aluminum plates; the three-dimensional camera is arranged at the end of the second mechanical arm, and is used to collect images of the seams to be welded of the two composite aluminum plates, the working path of the welding head and real-time working images.

[0058] The welding control module is used to drive the welding head and the three-dimensional camera to work, and to determine the spot welding position information and the welding path information according to the image of the seam to be welded acquired by the three-dimensional camera based on the visual positioning technology, and then feed back the information to the first robotic arm, so as to control the first robotic arm to adjust the posture in real time, drive the welding head to move along the spot welding position information and the welding path information, and complete the laser spot welding and laser continuous welding of the seam to be welded.

[0059] Furthermore, a transfer mechanism is provided at the bottom of the workbench, and when the seam to be welded exceeds the travel range of the first mechanical arm, the composite aluminum plate is moved to ensure the welding of the long seam to be welded. The transfer mechanism can be a motor guide rail structure, a motor lead screw structure, etc., which can complete the smooth movement of the workbench.

[0060] Furthermore, a welding working groove is provided on the upper surface of the workbench, and the seam to be welded is placed above the welding working groove. The length and width of the welding working groove both exceed the welding area, and are preferably 1.5 to 2 times of the welding area.

[0061] Furthermore, a preheating and cooling system is also arranged in the box, including: a heating module arranged in the welding working tank, and a cooling mechanism arranged above the composite aluminum plate.

[0062] The heating module is used to implement the preheating operation of step S2, specifically including: The lifting unit is a scissor-type lifting device arranged at the bottom of the welding working tank, driven by a motor, and used to lift the ceramic heater from the welding working tank to contact the lower surface of the composite aluminum plate; The ceramic heater is a long strip structure arranged at the top of the lifting unit, which is smaller than the welding working groove and is used to heat the surrounding area of ​​the composite aluminum plate to be welded; The temperature control unit integrates a temperature sensor and a controller to maintain the temperature of the area around the weld seam of the composite aluminum plate within a set range.

[0063] The design of the heating module in the present invention can heat the welding seam area and its surroundings in advance, so that the entire welding area reaches a relatively uniform temperature state before welding, thereby effectively reducing the stress and deformation caused by temperature difference during welding. The design of the lifting unit can lift the ceramic heater in the preheating step to heat the welding seam area and recover it after the temperature reaches the standard, thereby avoiding the ceramic heater from always contacting with the composite aluminum plate and causing damage to the ceramic heater during the welding process.

[0064] The cooling mechanism is used to cool down the laser welding after it is completed in step S4, and specifically includes: a gas supply unit, a gas distribution component, a gas outlet component, a temperature monitoring unit, a cooling control unit and a gas circulation unit.

[0065] The gas supply unit is one or more high-pressure argon cylinders, each of which is provided with a pressure reducing valve to reduce the high-pressure argon gas to a working pressure suitable for the welding area.

[0066] The gas distribution assembly comprises: a main pipeline connected to the pressure reducing valve, and a plurality of branch pipelines connected to the other end of the main pipeline; the branch pipelines are separated from the main pipeline and connected to various gas outlet points.

[0067] The gas outlet assembly includes: a plurality of nozzles and a flow control valve; the plurality of nozzles are evenly distributed along the length direction of the joint, vertically upwardly arranged or inclined toward the joint, and the flow control valve is installed in front of each nozzle to adjust the argon flow through the nozzle.

[0068] The temperature monitoring unit uses non-contact infrared thermometers that are evenly distributed along the length of the joint to monitor the temperature of the joint area in real time. Adjacent infrared thermometers are spaced 10 to 20 cm apart to cover the entire welding area and capture temperature gradient changes. The infrared thermometer can penetrate slight smoke and obstructions to accurately measure the surface temperature of the welding area, and does not contact the composite aluminum plate to avoid damage to the device during the laser welding process. Furthermore, the joint temperature distribution curve is obtained based on the collected temperatures at different positions in the joint area.

[0069] The cooling control unit establishes a cooling control strategy and dynamically adjusts the argon flow rate of nozzles at different positions to achieve the same cooling efficiency, specifically implementing step S43.

[0070] The gas circulation unit includes a return air duct arranged on the inner wall of the box body near the top, and a filtering system arranged in the return air duct; the return air duct is used to collect argon gas passing through the welding area and guide it back to the system or discharge it to the outside; the filtering system is used to clean impurities in the return air duct to ensure the purity of the argon gas circulation.

[0071] In step S3 of the present invention, a dust suction and fume exhaust system is used to extract the fume generated during the welding process; the dust suction and fume exhaust system includes: a mounting frame, an exhaust module arranged on the mounting frame, and an automatic adjustment module.

[0072] The exhaust module includes: a fan arranged outside the box, an air duct arranged at the output end of the fan, and an exhaust head arranged at the other end of the air duct; the exhaust head is connected to the end of the first robot arm through a mounting frame to keep the relative position of the exhaust head and the laser welding head fixed, and to extract the smoke generated by the laser welding in real time, so as to avoid the presence of smoke during the laser welding process, which affects the focusing and penetration ability of the laser, or even absorbs the energy of the laser beam, reduces the welding power, and causes insufficient welding depth and reduced weld quality.

[0073] The automatic adjustment module includes: a smoke monitoring unit, an air volume adjustment unit and an angle adjustment mechanism.

[0074] The smoke monitoring unit uses visual technology to obtain the concentration and distribution of smoke, which specifically includes the following steps: Step 1: Based on the real-time working image captured by the 3D camera, extract the smoke image and preprocess it. The preprocessing includes denoising, contrast enhancement and other operations to improve the quality of the extracted smoke image and increase the accuracy.

[0075] It is worth noting that the three-dimensional camera used in the present invention is a multi-spectral three-dimensional camera, which can penetrate a smoke layer of a certain thickness and capture clearer details of smoke distribution.

[0076] Step 2: Analyze the smoke image through image processing technology to obtain the concentration and distribution area of ​​the smoke.

[0077] Specifically, first use image segmentation technology, preferably use edge detection method to separate the smoke area from the image background, and accurately define the smoke area; use pixel value and grayscale parameters to quantitatively analyze the smoke area and estimate the concentration of the smoke; combine the depth information of the three-dimensional camera to construct a three-dimensional distribution model of the smoke and obtain the distribution area of ​​the smoke in space.

[0078] The air volume regulating unit sets a number of air volume gears based on the smoke concentration and the fan operating power, and adjusts the fan operating power in real time according to the smoke concentration obtained by the smoke monitoring unit.

[0079] The following is a setting of air volume gear, see Table 1: Table 1. Air volume setting

[0080] In the present invention, a real-time dynamic matching adjustment mechanism between fan power and smoke concentration is realized. This mechanism is designed to efficiently and accurately extract smoke from the laser welding box quickly, while minimizing the disturbance of the air in the welding box. By precisely controlling the fan power, the present invention significantly reduces smoke retention and its negative impact on the laser welding process (including laser focusing, penetration ability and welding power), while also effectively reducing the energy consumption of the fan, reflecting a high degree of energy efficiency optimization and environmental protection design concept.

[0081] The angle adjustment mechanism adjusts the angle of the exhaust head in real time according to the distribution area of ​​the smoke in the space output by the smoke monitoring unit; specifically, the smoke center is calculated according to the distribution area of ​​the smoke in the space, and the center of the exhaust head is adjusted to align with the center of the smoke, thereby improving the smoke capture efficiency.

[0082] It is worth noting that the mounting frame is fixedly connected to the end of the first robotic arm, and the other end of the mounting frame can drive the exhaust head to change its angle. It is preferably a multi-directional rotating robotic arm. The present invention does not limit the specific structure of the mounting frame, and it only needs to be able to achieve the rotation of the angle of the exhaust head.

[0083] Furthermore, a filter assembly is provided between the fan and the air duct to filter smoke and dust. Specifically, the filter assembly includes a primary filter layer, a medium filter layer and a high efficiency filter layer which are stacked; the primary filter layer is used to intercept large particles, the medium filter layer further refines the filtering effect, and the high efficiency filter layer ensures that the final discharged air meets environmental protection standards.

[0084] The present invention is provided with a dust suction and smoke exhaust system, and through the coordinated work of a smoke monitoring unit, an air volume adjustment unit and an angle adjustment mechanism, real-time monitoring of smoke concentration and distribution and automatic adjustment of the exhaust system are achieved, so that the exhaust head can be accurately aimed at the center of the smoke, thereby improving the smoke capture efficiency, and extracting the smoke generated in the laser welding process in real time, effectively avoiding the influence of smoke on the focusing and penetration ability of the laser, and preventing the problem of smoke absorbing the energy of the laser beam and causing a decrease in welding power, thereby ensuring the welding depth and weld quality, and improving the overall quality of the product.

[0085] The composite aluminum plate in this embodiment is a composite material of silicon nitride and aluminum, with a thickness of 1 to 3 mm, wherein the mass ratio of silicon nitride to aluminum is 1:9 to 15. This composite material is used as the refrigerator liner, utilizing the corrosion resistance and antibacterial properties of silicon nitride, thereby having the effects of improving corrosion resistance, extending service life and improving hygienic properties.

[0086] In step S3, the process parameters of laser continuous welding are: laser pulse peak power 1350-1700W, pulse waveform is rectangular wave, pulse width 3.5-4ms, welding speed 100mm / min-128mm / min, defocus amount -1mm--0.5mm. When the present invention performs seam welding on a composite aluminum plate with a thickness of 1-3mm, by controlling the combination of laser continuous welding process parameters within the above range, it is possible to ensure welding quality and efficiency while extending the existence time of the molten pool, so that hydrogen has more time to escape from the molten pool, and reduce the risk of pores forming during the solidification process of the molten pool.

[0087] Furthermore, the process parameters of laser continuous welding are: laser pulse peak power 1450~1620W, pulse width 3.5~4ms, welding speed 110mm / min~128mm / min, defocus -1mm~-0.5mm. Embodiment 1

[0088] Based on the above-mentioned laser welding process for the seam of refrigerator liner, a 2mm thick and 2mm long and wide laser welding process is used. The composite aluminum plate is laser welded along the length direction of the composite aluminum plate, specifically including the following steps: Step 1: First, the composite aluminum plate is mechanically polished and chemically cleaned in sequence, and then blown dry with argon gas. Then, the composite aluminum plate is placed in an oven for vacuum baking for 2 hours at a baking temperature of 120°C and a vacuum degree of 12Pa. Then, it is placed in a laser welding box for positioning. A welding seam extending along the welding direction is formed between the two composite aluminum plates, and the welding seam is automatically identified using visual positioning technology.

[0089] Step 2: Preheat the surrounding area of ​​the weld seam and control the temperature at 180°C. After preheating, laser spot weld the weld seam. The length of the weld seam is 1100mm, and laser spot welds are performed at both ends and the center of the weld seam.

[0090] Step 3: Perform continuous laser welding on the weld seam. The welding process parameters are set as follows: laser pulse peak power 1540W, pulse waveform is rectangular wave, pulse width 4ms, welding speed 115mm / min, defocus amount -0.5mm. During the welding process, the dust generated is extracted synchronously with the dust suction and exhaust system.

[0091] Step 4: After the laser continuous welding is completed, the joint area is flushed with argon gas. Specifically, 10 nozzles are set equidistantly above the joint. In the cooling control strategy, the highest temperature reached during laser welding in this embodiment is 2200°C, and the final target temperature after the joint is cooled is 40°C. The preset cooling rate control target is 110°C / s, and the proportional constant k=0.0153. The cooling method of the joint area of ​​the present invention is implemented, and the spray argon gas temperature is 80°C. When the temperature in the joint area drops below 200°C, switch to using room temperature argon gas, and slowly cool the temperature of the joint area to 40°C to complete the welding of the refrigerator liner seam. Embodiment 2

[0092] Based on Example 1, a 1 mm thick, 1 mm long, and 1 mm wide The composite aluminum plate is laser welded along the length of the composite aluminum plate. The welding process parameters in step 3 are adjusted as follows: laser pulse peak power 1350W, pulse waveform is rectangular wave, pulse width 3.5ms, welding speed 105mm / min, defocus amount -1mm. During the welding process, the dust generated is extracted synchronously with the dust extraction and exhaust system. Embodiment 3

[0093] Based on Example 1, a 3 mm thick, 3 mm long, and 3 mm wide The composite aluminum plate is laser welded along the length of the composite aluminum plate. The welding process parameters in step 3 are adjusted as follows: laser pulse peak power 1700W, pulse waveform is rectangular wave, pulse width 4ms, welding speed 125mm / min, defocus amount -1mm. During the welding process, the dust generated is extracted synchronously with the dust extraction and exhaust system.

[0094] Embodiments 4 and 5 Based on the first embodiment, the difference is that the peak power of the laser pulse in step three is adjusted to 1450W and 1620W respectively.

[0095] Comparative Examples 1, 2 and 3 Based on the first embodiment, the difference is that the peak power of the laser pulse in step three is adjusted to 1200W, 1900W and 2200W respectively.

[0096] Comparative Examples 4, 5 and 6 Based on the first embodiment, the difference is that the welding speeds in step three are adjusted to 90 mm / min, 138 mm / min and 150 mm / min respectively.

[0097] Comparative Example 7 Based on the first embodiment, the difference is that after the laser continuous welding is completed in step 4, the room temperature argon gas is directly used for circulation cleaning twice.

[0098] Comparative Example 8 Based on the first embodiment, the difference is that after the laser continuous welding is completed in step 4, a high flow rate of low-temperature argon gas is used for rapid cooling, the cooling rate is 200°C / s, and the argon gas temperature is controlled at -10 to 0°C.

[0099] The joints finally completed in the above embodiments and comparative examples were tested, and the testing contents included: using ultrasonic testing to evaluate the porosity in the joints, and using a Vickers hardness tester to test the hardness of the joints according to GB / T 2654-2008 "Test method for hardness of welded joints".

[0100] The results of the seam porosity test are as follows: Figure 2 The Vickers hardness of the composite aluminum plate used in the present invention is similar, with an average value of 134HV. Figure 3 The joint hardness expressed in is the percentage of the joint Vickers hardness reaching the hardness of the composite aluminum plate. Figure 2 and Figure 3 It can be seen that: In Examples 1 to 5 using the welding process of the present invention, where the process parameters of laser continuous welding are within the range of "laser pulse peak power 1350 to 1700 W, pulse waveform is a rectangular wave, pulse width 3.5 to 4 ms, welding speed 100 mm / min to 128 mm / min, defocus amount -1 mm to -0.5 mm", the porosity at the joints after completion all reached less than 0.6%, and the Vickers hardness at the joints also reached more than 85% of the hardness of the composite aluminum plate, with excellent performance.

[0101] In addition, in Examples 1 to 3 using the welding process of the present invention, where the process parameters of laser continuous welding are within the range of "laser pulse peak power 1450 to 1620 W, pulse width 3.5 to 4 ms, welding speed 110 mm / min to 128 mm / min, defocus amount -1 mm to -0.5 mm", the porosity at the joints after completion is less than 0.3%, or even 0, and the Vickers hardness at the joints is more than 88% of the hardness of the composite aluminum plate, which is an extremely excellent performance.

[0102] Relatively speaking, although the comparative example 1 can achieve the effect of extending the existence time of the molten pool due to the low laser pulse power, the low power leads to the unstable existence of the molten pool, and the hydrogen discharge effect and hardness performance are not ideal; while the comparative examples 2 and 3 are both laser pulse power high, and the laser welding is carried out at a welding speed of 115mm / min, resulting in an excessively large molten pool at the joint and poor joint hardness. For comparative example 4, the welding speed is too slow, one is low efficiency, and the other is that the slow welding speed causes the molten pool at the joint to become larger, generating more hydrogen, and the porosity and hardness performance are worse than the embodiment; and for comparative examples 5 and 6, the welding speed is too fast, the existence time of the molten pool is short, and the hydrogen has no time to be discharged.

[0103] Comparative Examples 7 and 8 are adjustments to the cooling method after welding. Figure 2 and Figure 3 According to the test results, Comparative Example 7 uses room temperature argon gas for circulating cleaning, and Comparative Example 8 uses low-temperature argon gas for rapid cooling. Compared with Example 1, the cooling rates are arranged from fast to slow as follows: Comparative Example 8, Comparative Example 7 and Example 1. The cooling rate is too fast. Compared with the slow cooling measures in Example 1, the existence time of the molten pool is greatly shortened. The hydrogen generated during welding has no time to escape, and there is a greater risk of pores forming during the solidification of the molten pool, which leads to poor hardness.

[0104] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A laser welding process for refrigerator liner seams, characterized in that: The following steps are involved: Step S1, after pre-processing the composite aluminum plate, put it into a laser welding box, position the two composite aluminum plates so that a seam to be welded extending along the welding direction is formed between the two composite aluminum plates, and the seam to be welded is automatically identified by using visual positioning technology; Step S2, based on the recognition result of step S1, preheating the surrounding area of ​​the weld to be welded, controlling the temperature at 150-200° C., and performing laser spot welding at multiple equidistant points on the weld to be welded after the preheating temperature reaches the standard, keeping the weld to be welded relatively fixed; Step S3, performing laser continuous welding on the seam to be welded, the process parameters of the laser continuous welding are: laser pulse peak power 1350-1700W, pulse waveform is rectangular wave, pulse width 3.5-4ms, welding speed 100mm / min-128mm / min, defocus amount -1mm--0.5mm, and during the welding process, the generated smoke is synchronously extracted; Step S4: After the laser continuous welding is completed, the joint area is flushed with argon gas to slowly cool the temperature of the joint area to room temperature, thereby completing the welding of the refrigerator liner joint; In step S4, the cooling method of the joint area includes the following steps: Step S41, arranging a number of infrared thermometers evenly distributed along the length direction of the joint, monitoring the temperature of the joint area in real time, and generating a joint temperature distribution curve based on the collected temperatures at different positions in the joint area; Step S42, arranging a plurality of nozzles above the joint area, each nozzle being provided with a flow control valve, the nozzle being connected to an argon gas supply unit through a pipeline, and spraying argon gas toward the joint area; Step S43, establishing a cooling control strategy, dynamically adjusting the argon flow rate of nozzles at different positions according to the joint temperature distribution curve output by the temperature monitoring unit to achieve the same cooling efficiency; In step S41, the generation of the joint temperature distribution curve specifically includes the following steps: Step S411, dividing the measuring point coordinates for each infrared thermometer along the length direction of the joint, which is the X-axis coordinate in the joint temperature distribution curve; Step S412, arranging the seam temperature data collected by each infrared thermometer according to the corresponding measuring point coordinates, and performing interpolation processing to estimate the temperature value of the unmeasured point, that is, the Y-axis coordinate in the seam temperature distribution curve; Step S413, the temperature data after interpolation processing are sequentially connected using a curve according to the order of the measuring point coordinates to obtain a joint temperature distribution curve, where the X-axis represents the position in the length direction of the joint, and the Y-axis represents the temperature value; In step S43, the establishment of the cooling control strategy includes the following steps: Step S431: Determine the final target temperature of the joint after cooling based on the thickness, material and maximum temperature reached during welding of the composite aluminum plate. 30~40℃, and preset cooling rate control target ; Step S432: Divide the joint temperature distribution curve into several cooling sub-areas according to the nozzle position , for each cooling sub-area , calculate the average temperature ,in The cooling sub-area The number of measuring points within Step S433: Calculate each cooling sub-area Argon flow rate of inner nozzle , where k is the proportionality constant, For cooling time, .

2. The laser welding process for the seam of the refrigerator liner according to claim 1 is characterized in that: The composite aluminum plate is a composite material of silicon nitride and aluminum, and has a thickness of 1 to 3 mm.

3. The laser welding process for the seam of the refrigerator liner according to claim 1 is characterized in that: In step S2, preheating the surrounding area of ​​the weld to be welded specifically includes the following steps: Step S21, based on the recognition result of the weld to be welded in step S1, move the ceramic heater closer to the composite aluminum plate from the bottom of the composite aluminum plate until it contacts the bottom surface of the composite aluminum plate, and the position of the ceramic heater is directly above the weld to be welded area; Step S22, start the ceramic heater to heat the seam area to be welded of the composite aluminum plate, detect the temperature of the seam area to be welded in real time, stop heating after the temperature of each location in the seam area to be welded reaches 150-200°C, and recycle the ceramic heater.

4. The laser welding process for the seam of a refrigerator liner according to claim 1 is characterized in that: The preprocessing in step S1 specifically includes the following steps: Step S11, mechanically grinding the butt weld area of ​​the composite aluminum plate until the weld area reveals a metallic luster; Step S12, using acetone and anhydrous ethanol to clean the composite aluminum plate in sequence, wiping the surface of the composite aluminum plate with dust-free paper, and then blowing the surface of the composite aluminum plate dry with argon gas; Step S13, placing the composite aluminum plate in an oven for vacuum baking for 1 to 3 hours, the baking temperature is 100 to 140° C., and the vacuum degree is 9 to 14 Pa.

5. The laser welding process for the seam of the refrigerator liner according to claim 1 is characterized in that: The laser welding box is filled with argon gas, and the water and oxygen contents are both below 20 PPM; the laser welding box comprises: a box body, a workbench arranged in the center of the box body, a laser welding system and a dust and fume exhaust system arranged inside the box body; The workbench is provided with a clamping mechanism for positioning the two composite aluminum plates; The laser welding system comprises: a welding head, a first mechanical arm, a second mechanical arm, a three-dimensional camera and a welding control module; the first mechanical arm and the second mechanical arm both have a plurality of freely movable joints and are arranged at the upper position of the inner wall of the box body; wherein the welding head is arranged at the end of the first mechanical arm, and is used for laser welding the seams to be welded of the two composite aluminum plates; the three-dimensional camera is arranged at the end of the second mechanical arm, and is used for collecting images of the seams to be welded of the two composite aluminum plates, the working path of the welding head and real-time working images; The welding control module is used to drive the welding head and the three-dimensional camera to work, and to determine the spot welding position information and the welding path information according to the image of the seam to be welded acquired by the three-dimensional camera based on the visual positioning technology, and then feed back the information to the first robotic arm, so as to control the first robotic arm to adjust its posture in real time, drive the welding head to move along the spot welding position information and the welding path information, and complete the laser spot welding and laser continuous welding of the seam to be welded.

6. The laser welding process for the seam of the refrigerator liner according to claim 5 is characterized in that: In the step S3, the dust generated during the welding process is extracted using the dust suction and fume exhaust system; The dust collection and smoke exhaust system comprises: a mounting frame, an exhaust module arranged on the mounting frame, and an automatic adjustment module; The exhaust module includes: a fan arranged outside the box, an air duct arranged at the output end of the fan, and an exhaust head arranged at the other end of the air duct; the exhaust head is connected to the end of the first mechanical arm through the mounting frame to extract smoke and dust generated by laser welding in real time; The automatic adjustment module comprises: Smoke monitoring unit, which uses visual technology to obtain smoke concentration and distribution; An air volume regulating unit, which sets a plurality of air volume gears based on smoke concentration and fan operating power, and adjusts the fan operating power in real time according to the smoke concentration obtained by the smoke monitoring unit; The angle adjustment mechanism adjusts the angle of the exhaust head in real time according to the distribution area of ​​the smoke in the space output by the smoke monitoring unit; specifically, the smoke center is calculated according to the distribution area of ​​the smoke in the space, and the center of the exhaust head is adjusted to align with the smoke center.

7. The laser welding process for the seam of a refrigerator liner according to claim 1, characterized in that: The process parameters of the laser continuous welding are: laser pulse peak power 1450-1620W, pulse width 3.5-4ms, welding speed 110mm / min-128mm / min, and defocusing amount -1mm--0.5mm.

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