In-situ observation device and in-situ observation method for dynamic process of pore defect in laser-arc hybrid welding

Abstract

The invention discloses an in-situ observation device and an in-situ observation method for a laser-arc hybrid welding pore defect dynamic process, belongs to the technical field of welding process monitoring, and aims to solve the problems that generation, growth and flow changes of pores are difficult to observe during observation due to limitation of real-time observation in the existing laser-arc hybrid welding field. According to the method, primary imaging is carried out according to the intensity difference after the rays penetrate through the molten pool and the base metal, the X-ray signals are converted into the corresponding visible light signals, then high-frame-rate image capture is achieved through high-speed camera shooting, and the dynamic behavior of the air holes in the welding process is reflected in real time. The image processing system is used for recognizing the characteristics of the air holes according to the brightness difference in the image area and identifying the real-time positions of the air holes, the X-ray real-time monitoring method is used, a clearer and more accurate in-situ monitoring method is provided for the air hole defects generated in the laser-arc hybrid welding process, and the real-time monitoring accuracy of the air holes is improved. And a more reliable and objective real-time reference is provided for welding process optimization.

Description

Technical Field

[0001] The invention belongs to the technical field of welding process monitoring, and specifically relates to an in-situ observation device and an in-situ observation method for a dynamic process of a laser-arc hybrid welding porosity defect. Background Art

[0002] As a high-energy-density welding method, laser has significant advantages such as high efficiency, low heat input, precise heat-affected zone control and flexibility. However, the higher energy density and smaller laser spot not only make the gap adaptability of laser welding poor, but also cause a large amount of metal vapor to be generated during the laser welding process, resulting in decreased stability of the laser welding process and poor weld formation. Especially for high-reflectivity materials such as aluminum alloys, the weld quality obtained by single laser welding is often difficult to meet the requirements of actual engineering applications.

[0003] Laser-arc hybrid welding uses laser and arc coupled heat sources, which act on the metal molten pool at the same time, making it not only have the advantages of high speed and high efficiency of laser welding, but also the introduction of arc improves the metal's absorption rate of laser, enhances the bridging ability of the molten pool, and reduces the occurrence of welding defects. However, due to the complex coupling relationship between the dual heat sources, there is a complex molten pool flow process in the laser-arc hybrid welding process. When the laser irradiates the molten pool, the extremely high energy density causes the metal to evaporate rapidly and generate recoil pressure, thereby forming a keyhole in the molten pool. As the molten pool moves, the keyhole will also open and close periodically, but when the keyhole closes, it will cause gas to be drawn into the molten pool to form bubbles. If the bubbles cannot be removed in time, they will remain in the weld after the molten pool solidifies to form pores. These pores will become weak areas under load conditions in the weld, seriously affecting the mechanical properties of the joint. Therefore, real-time observation of the pore defects of laser-arc hybrid welding is an important way to control the pore generation in the hybrid welding process and improve the service performance of the joint. However, due to the complexity of the action mode and system structure of the laser-arc hybrid welding heat source, conventional monitoring methods often cannot meet the requirements of real-time observation for equipment miniaturization and device flexibility. At the same time, due to the small time scale of the behavior of pores and keyholes in the molten pool, the observation of pore defects in laser-arc hybrid welding requires higher resolution and image frame rate.

[0004] Chinese patent CN 107378281 A discloses a method for monitoring the dynamic behavior characteristics of the laser welding molten pool and the keyhole. The method uses a "sandwich" structure to set a high-temperature resistant transparent glass on one side of the workpiece to be welded, and uses the glass to take real-time photos of the side of the workpiece adjacent to the glass, thereby realizing intuitive monitoring of the dynamic behavior of the welding molten pool, keyhole and pores. However, the "sandwich" structure used in this method is significantly different from the heat conduction and molten pool stress conditions of the actual welding process. Chinese patent CN 113210852 A discloses a laser welding process monitoring method based on in-situ measurement of the orifice diameter distortion rate. The method extracts the horizontal and vertical diameters of the small holes by high-speed photography of the molten pool surface, and establishes the ratio of the horizontal and vertical diameters, the impact of the light-induced steam on the keyhole, and the connection between the welding defects such as pores, spatter and weld surface formation, thereby realizing the monitoring of the pore state of the welding process. Although this method is simple and efficient, it only uses the keyhole morphology on the molten pool surface to describe the pores and molten pool flow behavior, which is somewhat one-sided and difficult to fully reflect the complex dynamic process in the molten pool. Chinese patent CN 114559160 A discloses an in-situ detection method for pores in laser-arc hybrid non-penetration welding. This method uses the phenomenon that when the keyhole collapses to form pores, the steam ejected from the keyhole mouth decreases and the metal plasma decreases. By collecting the characteristic linear spectrum intensity of the metal plasma radiation, the minimum plasma intensity area is identified as the pore, thereby realizing the extraction of the pore state of the welding process. However, it is difficult to intuitively describe the generation, growth, and flow process of pores inside the molten pool by analyzing the pore state through plasma intensity. Chinese patent CN 115889975 B discloses a laser welding process monitoring system and method. This method uses a pyrometer and weak coherent optical tomography technology to collect infrared temperature signals and spectral signals of the molten pool, and combines data fitting and empirical mode decomposition to track pores, unfilled, leaked welds, and misweld defects. This method only uses the surface information of the molten pool to describe defects such as welding pores, and it is difficult to intuitively show the dynamic behavior of pores inside the molten pool. In addition, the observation system in CN202410107557.9 uses an X-ray detector to detect the welding molten pool, but due to the detection principle it adopts, it can only judge the keyhole fluctuation through the numerical values ​​shown in the X-ray detector, and cannot perform high frame rate shooting of the overall welding real-time dynamics.

[0005] In summary, developing a high-frame rate method that can intuitively and reliably realize the dynamic behavior of pores inside the molten pool during laser-arc hybrid welding is of great significance for in-depth analysis of the flow behavior of the laser-arc hybrid welding molten pool, eliminating internal pore defects, and improving the mechanical properties of the joint. Summary of the invention

[0006] In order to solve the limitations of real-time observation in the existing laser-arc hybrid welding field and the problem that it is difficult to intuitively observe the generation, growth and flow changes of pores in the in-situ process, the present invention provides an in-situ observation device and an in-situ observation method for the dynamic process of porosity defects in laser-arc hybrid welding.

[0007] An in-situ observation device for the dynamic process of porosity defects in laser-arc hybrid welding, the observation device comprising an X-ray generating system, a laser-arc hybrid welding system, an X-ray imaging system and an image processing system, the X-ray generating system, the laser-arc hybrid welding system and the X-ray imaging system being arranged in sequence from left to right, the signal output end of the X-ray imaging system being connected to the signal input end of the image processing system through a wire, the X-rays emitted by the X-ray generating system passing through a workpiece to be welded on the laser-arc hybrid welding system are received by the X-ray imaging system and image processing is performed on the image through the image processing system;

[0008] Further, the laser-arc hybrid welding system includes an arc welding gun, a laser head, a traveling mechanism, a fixture, a welding gun bracket, a test platform and a laser head bracket, the welding gun bracket and the laser head bracket are relatively arranged at two ends of the test platform, and the bottom of the welding gun bracket and the bottom of the laser head bracket are fixedly connected to the test platform, the traveling mechanism is arranged at the top center of the test platform, and the fixed part of the traveling mechanism is fixedly connected to the test platform, the fixture is fixed on the movable part of the traveling mechanism, the traveling mechanism can drive the fixture to move along the welding track, the arc welding gun is installed on the welding gun bracket, the laser head is installed on the laser head bracket, the workpiece to be welded is clamped on the fixture, and the welding wire and the laser head in the arc welding gun are arranged corresponding to the weld on the workpiece to be welded;

[0009] Furthermore, the X-ray imaging system includes an X-ray image intensifier, an image intensifier input screen, an image intensifier output screen and a high-speed camera, wherein the image intensifier input screen is installed at the ray input end of the X-ray image intensifier, the image intensifier output screen is installed at the ray output end of the X-ray image intensifier, the high-speed camera is arranged on a side of the X-ray image intensifier away from the laser-arc hybrid welding system, and the shooting end of the high-speed camera is arranged toward the image intensifier output screen, and the image output end of the high-speed camera is connected to the signal input end of the image processing system through a wire;

[0010] Furthermore, the laser type used by the laser head is a fiber laser, a disk laser, a semiconductor laser or a Nd-YAG laser;

[0011] Further, the arc type used by the arc welding gun is TIG arc, MIG / MAG arc or plasma arc;

[0012] Furthermore, the laser-arc hybrid welding system adopts a coaxial or side-axis hybrid method; the welding machine current is controlled at 50-150A, the laser power is 800-4000W, and continuous welding is achieved by fixing the heat source and moving the walking mechanism. The welding speed is set to 0.5-8mm / s, and an oscillating laser with an oscillation amplitude of 0.5-6mm and an oscillation frequency of 50-250Hz is used for welding;

[0013] Furthermore, the X-ray generating system is a 100-300 kV ray source, and the ray parameters of the X-ray generating system are tube voltage 120-200 kV, tube current 100-250 μA, and focal spot size <10 μm;

[0014] Furthermore, the X-ray image intensifier performs primary imaging, the source-object distance d1 is 3 to 20 cm, the object-image distance d2 is 40 to 60 cm, and the magnification ratio is 1:4 to 1:8;

[0015] Furthermore, the high-speed camera performs secondary imaging, the lens magnification is 1:1 to 1:1.5, the shooting frame rate is 500 to 1000 FPS, the exposure time is 0.5 to 1 ms, and the shooting time is 5 to 8 s;

[0016] A method for in-situ observation of a dynamic process of porosity defects in laser-arc hybrid welding is achieved by the following steps:

[0017] Step 1: Use a 4-8 mm thick metal block as the workpiece to be welded, and fix it on the walking mechanism of the welding system. Fix the arc welding gun and the laser head on the test platform through the welding gun bracket and the laser head bracket;

[0018] Step 2: Adjust the imaging magnification ratio; ensure that the X-ray generating system, the molten pool area on the workpiece to be welded and the center of the X-ray imaging system are located on the same axis, control the primary imaging ratio by the distance between the X-ray generating system and the workpiece to be welded (source-object distance d1) and the distance between the workpiece to be welded and the input screen of the image intensifier (object-image distance d2), and control the secondary imaging ratio by adjusting the focal length of the high-speed camera lens;

[0019] Step 3: Set system parameters; set the moving speed of the walking mechanism; set the arc welding machine current value, laser output power value and other welding parameters; set the X-ray tube current, tube voltage and focal size; set the high-speed camera shooting frame rate, exposure time and shooting time;

[0020] Step 4: After completing the parameter adjustment, turn on the X-ray generation system and the X-ray imaging system, and start welding after the system is stable. Use a high-speed camera to take real-time photos of the welding molten pool displayed on the image intensifier output screen;

[0021] Step 5: Perform image processing on the captured images and videos, and distinguish and extract the pores in the molten pool by increasing the contrast and binarization, so as to monitor the dynamic behavior of welding pores.

[0022] The beneficial effects of this application compared to the prior art are as follows:

[0023] The present application provides an in-situ observation device and an in-situ observation method for the dynamic process of porosity defects in laser-arc hybrid welding. Compared with the prior art, the in-situ observation device provided by the present application has a simple structure and convenient operation, and realizes intuitive and real-time monitoring of the porosity behavior in the molten pool during laser-arc hybrid welding. The in-situ observation method provided by the present application has a wide range of applicability and can be applied to the welding process of various metal materials such as steel, aluminum alloy, magnesium alloy, titanium alloy, etc. Especially for materials such as aluminum alloys that are prone to porosity defects, the present invention can realize real-time observation of the dynamic behavior of the molten pool, the generation, growth and flow of pores during the composite welding process, and provides a new perspective for in-depth understanding of the mechanism of pore formation. Through the precise monitoring of these dynamic processes, the present invention provides important experimental data support and theoretical basis for the optimization of welding technology, which helps to effectively reduce welding defects and improve the overall quality and mechanical properties of joints. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of the in-situ observation device for the dynamic process of porosity defects in laser-arc hybrid welding described in this application;

[0025] Figure 2 This is a schematic diagram of the structure of the laser-arc hybrid welding system described in this application;

[0026] Figure 3 The dynamic behavior characteristics of pores in laser-arc hybrid welding obtained by the method provided in this application;

[0027] In the figure, 1 is an X-ray generating system, 2 is a laser-arc hybrid welding system, 21 is an arc welding gun, 22 is a laser head, 23 is a workpiece to be welded, 24 is a walking mechanism, 25 is a fixture, 26 is a welding wire, 27 is a welding gun bracket, 28 is a test platform, 29 is a laser head bracket, 3 is an X-ray imaging system, 31 is an X-ray image intensifier, 32 is an image intensifier input screen, 33 is an image intensifier output screen, 34 is a high-speed camera, 4 is an image processing system, d1 is a source-object distance, d2 is an object-image distance, α is an angle between the welding gun and the laser head axis, and D is a light wire spacing. DETAILED DESCRIPTION

[0028] Specific implementation method 1: Combination Figure 1 to Figure 2To explain this embodiment, an in-situ observation device for the dynamic process of porosity defects in laser-arc hybrid welding is provided in this embodiment. The observation device includes an X-ray generating system 1, a laser-arc hybrid welding system 2, an X-ray imaging system 3 and an image processing system 4. The X-ray generating system 1, the laser-arc hybrid welding system 2 and the X-ray imaging system 3 are arranged in sequence from left to right. The signal output end of the X-ray imaging system 3 is connected to the signal input end of the image processing system 4 through a wire. The X-rays emitted by the X-ray generating system 1 pass through a workpiece 23 to be welded located on the laser-arc hybrid welding system 2 and are received by the X-ray imaging system 3 and the image is processed by the image processing system 4.

[0029] The in-situ observation device provided in this embodiment has a working principle based on that under specific welding parameters, the metal melts under the combined action of laser and arc, the laser beam irradiates the liquid metal to generate metal vapor, and then forms a welding keyhole. When the keyhole collapses, welding pores are generated in the molten pool. Due to the density difference between pores, liquid metal and solid metal, the attenuation degree of X-rays when passing through these areas is different, which causes the intensity of the rays input to the imaging system to change. The imaging system first performs an imaging according to the difference in ray intensity, converts the X-ray signal into a corresponding visible light signal, and then realizes high-frame rate image capture through high-speed camera, which reflects the dynamic behavior of pores during welding in real time. The image processing system uses the brightness difference in the image area to identify the pore features and mark their real-time positions. The present invention uses the method of real-time X-ray monitoring to provide a clearer and more accurate in-situ monitoring method for pore defects generated during laser-arc hybrid welding, and provides a more reliable and objective real-time reference for welding process optimization.

[0030] Specific implementation method 2: Combination Figure 1 to Figure 2 The present embodiment is described. The present embodiment differs from the first embodiment in that the laser-arc hybrid welding system 2 comprises an arc welding gun 21, a laser head 22, a traveling mechanism 24, a fixture 25, a welding gun bracket 27, a test platform 28 and a laser head bracket 29. The welding gun bracket 27 and the laser head bracket 29 are relatively arranged at two ends of the test platform 28, and the bottom of the welding gun bracket 27 and the bottom of the laser head bracket 29 are both fixedly connected to the test platform 28. The traveling mechanism 24 is arranged at the top center of the test platform 28, and the fixed part of the traveling mechanism 24 is fixedly connected to the test platform 28. The fixture 25 is fixed on the movable part of the traveling mechanism 24. The traveling mechanism 24 can drive the fixture 25 to move along the welding track. The arc welding gun 21 is installed on the welding gun bracket 27, the laser head 22 is installed on the laser head bracket 29, the workpiece 23 to be welded is clamped on the fixture 25, and the welding wire 26 in the arc welding gun 21 and the laser head 22 are both arranged corresponding to the weld on the workpiece 23 to be welded. Other components and connection methods are the same as those in the first embodiment.

[0031] In this embodiment, the walking mechanism 24 is used to drive the fixture 25 and the workpiece 23 to be welded to move along a predetermined welding trajectory and cooperate with the arc welding gun 21 and the laser head 22 to complete the welding work. The walking mechanism 24 is a screw slider mechanism, and the power source is a DC motor. The fixture 25 is used to fix the workpiece 23 to be welded. The arc welding gun 21 uses a CMT welding gun, and the specific model is TPS3200CMT welding machine. The laser head 22 uses an IPG laser head, and the specific model is IPG D50 Wobble laser head, the workpiece 23 to be welded is 5 series aluminum alloy material. In the specific arrangement, the arc welding gun 21 and the laser head 22 are respectively installed on the welding gun bracket 27 and the laser head bracket 29, and ensure that the welding wire 26 and the laser head 22 are arranged correspondingly to the weld on the workpiece 23 to be welded. During welding, the working positions of the arc welding gun 21 and the laser head 22 are fixed, and the welding work is completed by relying on the movement of the workpiece 23 to be welded. The thickness of the above-mentioned workpiece to be measured is selected to be 5mm, which ensures that the rays can penetrate smoothly while increasing the contrast between the liquid molten pool, pores and unmelted metal.

[0032] Specific implementation method three: Combination Figure 1 to Figure 2 This embodiment is described. The difference between this embodiment and the second embodiment is that the X-ray imaging system 3 includes an X-ray image intensifier 31, an image intensifier input screen 32, an image intensifier output screen 33 and a high-speed camera 34. The image intensifier input screen 32 is installed at the ray input end of the X-ray image intensifier 31, the image intensifier output screen 33 is installed at the ray output end of the X-ray image intensifier 31, the high-speed camera 34 is arranged on the side of the X-ray image intensifier 31 away from the laser-arc hybrid welding system 2, and the shooting end of the high-speed camera 34 is arranged toward the image intensifier output screen 33. The image output end of the high-speed camera 34 is connected to the signal input end of the image processing system 4 through a wire. Other components and connection methods are the same as those of the second embodiment.

[0033] In this embodiment, the X-ray image intensifier 31 selects a Canon X-ray image intensifier, and the high-speed camera 34 is located on one side of the image intensifier output screen 33 in the X-ray image intensifier 31. When the X-ray imaging system 3 is working, the X-ray signal after penetrating the workpiece is received by the impact intensifier input screen 32, and is converted into a visible light signal and displayed on the output screen 33 and captured in real time at a high frame rate by the high-speed camera 34; the image processing system 4 uses an industrial PC to process the image information collected by the high-speed camera 34 to obtain a dynamic image of the porosity defect in the composite welding process.

[0034] Specific implementation method four: Combination Figure 1 to Figure 2This embodiment is described. The difference between this embodiment and the third embodiment is that the laser type used by the laser head 22 is a fiber laser, a disk laser, a semiconductor laser or a Nd-YAG laser. The other components and connection methods are the same as those of the third embodiment.

[0035] Specific implementation method five: Combination Figure 1 to Figure 2 This embodiment is described. The difference between this embodiment and the fourth embodiment is that the arc type used by the arc welding gun 21 is TIG arc, MIG / MAG arc or plasma arc. The other components and connection methods are the same as those of the fourth embodiment.

[0036] Specific implementation method six: Combination Figure 1 to Figure 2 This embodiment is described. The difference between this embodiment and the fifth embodiment is that the laser-arc hybrid welding system 2 adopts a coaxial or side-axis hybrid method; the welding machine current is controlled at 50-150A, the laser power is 800-4000W, and continuous welding is achieved by fixing the heat source and moving the walking mechanism. The welding speed is set to 0.5-8mm / s, and a swinging laser with a swing amplitude of 0.5-6mm and a swing frequency of 50-250Hz is used for welding. Other components and connection methods are the same as those of the fifth embodiment.

[0037] Specific implementation method seven: Combination Figure 1 to Figure 2 This embodiment is described. The difference between this embodiment and the sixth embodiment is that the X-ray generating system 1 is a 100-300 kV ray source, and the ray parameters of the X-ray generating system 1 are tube voltage 120-200 kV, tube current 100-250 μA, and focal spot size <10 μm. Its composition and connection method are the same as those of the sixth embodiment.

[0038] In this embodiment, the X-ray generating system 1 uses a FineTec 300kV micro-focus ray source, the X-ray tube voltage is selected to be 180kV, and the image contrast is controlled by adjusting the tube current, which can improve the recognition of pores and edge contrast in the image.

[0039] Specific implementation method eight: Combination Figure 1 to Figure 2 This embodiment is described. The difference between this embodiment and the seventh embodiment is that the X-ray image intensifier 31 performs primary imaging, the source-object distance d1 is 3 to 20 cm, the object-image distance d2 is 40 to 60 cm, and the magnification ratio is 1:4 to 1:8. Other components and connection methods are the same as those of the seventh embodiment.

[0040] Specific implementation method nine: Combination Figure 1 to Figure 2This embodiment is described. The difference between this embodiment and the eighth embodiment is that the high-speed camera 34 performs secondary imaging, the lens magnification is 1:1 to 1:1.5, the shooting frame rate is 500 to 1000 FPS, the exposure time is 0.5 to 1 ms, and the shooting time is 5 to 8 s. The other components and connection methods are the same as those of the eighth embodiment.

[0041] Specific implementation method ten: Combination Figures 1 to 3 This embodiment describes an in-situ observation device for the dynamic process of porosity defects in laser-arc hybrid welding. The method is implemented by the following steps:

[0042] Step 1: Use a 4-8 mm thick metal block as the workpiece 23 to be welded, and fix it on the walking mechanism 24 of the welding system, and fix the arc welding gun 21 and the laser head 22 on the test platform 28 through the welding gun bracket 27 and the laser head bracket 29;

[0043] Step 2: Adjust the imaging magnification ratio; ensure that the X-ray generating system 1, the molten pool area on the workpiece 23 to be welded and the center of the X-ray imaging system 3 are located on the same axis, and control the primary imaging ratio by the source-object distance d1 between the X-ray generating system 1 and the workpiece 23 to be welded and the object-image distance d2 between the workpiece 23 to be welded and the image intensifier input screen 32, and control the secondary imaging ratio by adjusting the focal length of the high-speed camera lens;

[0044] Step 3: Set system parameters; set the moving speed of the walking mechanism; set the arc welding machine current value, laser output power value and other welding parameters; set the X-ray tube current, tube voltage and focal size; set the high-speed camera shooting frame rate, exposure time and shooting time;

[0045] Step 4: After completing the parameter adjustment, turn on the X-ray generating system 1 and the X-ray imaging system 3, and start welding after the system is stable, and use the high-speed camera 34 to take real-time photos of the welding molten pool displayed on the image intensifier output screen 33;

[0046] Step 5: Perform image processing on the captured images and videos, and distinguish and extract the pores in the molten pool by increasing the contrast and binarization, so as to monitor the dynamic behavior of welding pores.

[0047] The present invention has been disclosed as above with preferred implementation cases, but it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above implementation cases based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An in-situ observation device for the dynamic process of porosity defects in laser-arc hybrid welding, characterized in that: The observation device comprises an X-ray generating system (1), a laser-arc hybrid welding system (2), an X-ray imaging system (3) and an image processing system (4). The X-ray generating system (1), the laser-arc hybrid welding system (2) and the X-ray imaging system (3) are arranged in sequence from left to right. The signal output end of the X-ray imaging system (3) is connected to the signal input end of the image processing system (4) through a wire. The X-rays emitted by the X-ray generating system (1) pass through a workpiece (23) to be welded located on the laser-arc hybrid welding system (2) and are then received by the X-ray imaging system (3) and image processing is performed on the image through the image processing system (4).

2. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 1, characterized in that: The laser-arc hybrid welding system (2) comprises an arc welding gun (21), a laser head (22), a walking mechanism (24), a fixture (25), a welding gun bracket (27), a test platform (28) and a laser head bracket (29), wherein the welding gun bracket (27) and the laser head bracket (29) are arranged at two ends of the test platform (28) relative to each other, and the bottom of the welding gun bracket (27) and the bottom of the laser head bracket (29) are fixedly connected to the test platform (28), the walking mechanism (24) is arranged at the top center of the test platform (28), and the walking mechanism (24) is arranged at the top center of the test platform (28). The fixed part of the walking mechanism (24) is fixedly connected to the test platform (28), the clamp (25) is fixed on the movable part of the walking mechanism (24), the walking mechanism (24) can drive the clamp (25) to move along the welding track, the arc welding gun (21) is installed on the welding gun bracket (27), the laser head (22) is installed on the laser head bracket (29), the workpiece (23) to be welded is clamped on the clamp (25), and the welding wire (26) in the arc welding gun (21) and the laser head (22) are both arranged corresponding to the welding seam on the workpiece (23) to be welded.

3. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 1, characterized in that: The X-ray imaging system (3) comprises an X-ray image intensifier (31), an image intensifier input screen (32), an image intensifier output screen (33) and a high-speed camera (34). The image intensifier input screen (32) is installed at the ray input end of the X-ray image intensifier (31), the image intensifier output screen (33) is installed at the ray output end of the X-ray image intensifier (31), the high-speed camera (34) is arranged on a side of the X-ray image intensifier (31) away from the laser-arc hybrid welding system (2), and the shooting end of the high-speed camera (34) is arranged toward the image intensifier output screen (33). The image output end of the high-speed camera (34) is connected to the signal input end of the image processing system (4) through a wire.

4. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 2, characterized in that: The laser type adopted by the laser head (22) is optical fiber laser, disk laser, semiconductor laser or Nd-YAG laser.

5. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 2, characterized in that: The arc type adopted by the arc welding gun (21) is TIG arc, MIG / MAG arc or plasma arc.

6. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 2, characterized in that: The laser-arc hybrid welding system (2) adopts a coaxial or side-axis hybrid method; the welding machine current is controlled at 50-150A, the laser power is 800-4000W, and continuous welding is achieved by fixing the heat source and moving the walking mechanism. The welding speed is set to 0.5-8mm / s, and an oscillating laser with an oscillation amplitude of 0.5-6mm and an oscillation frequency of 50-250Hz is used for welding.

7. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 1, characterized in that: The X-ray generating system (1) is a 100-300 kV ray source, and the ray parameters of the X-ray generating system (1) are tube voltage 120-200 kV, tube current 100-250 μA, and focal spot size <10 μm.

8. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 3, characterized in that: The X-ray image intensifier (31) performs primary imaging, the source-object distance d1 is 3 to 20 cm, the object-image distance d2 is 40 to 60 cm, and the magnification ratio is 1:4 to 1:

8.

9. The in-situ observation device for dynamic process of porosity defects in laser-arc hybrid welding according to claim 3, characterized in that: The high-speed camera (34) performs secondary imaging, the lens magnification is 1:1 to 1:1.5, the shooting frame rate is 500 to 1000 FPS, the exposure time is 0.5 to 1 ms, and the shooting time is 5 to 8 s.

10. An in-situ observation method using the in-situ observation device for dynamic process of laser-arc hybrid welding porosity defects according to any one of claims 1 to 9, characterized in that: The method is achieved by the following steps: Step 1: A metal block with a thickness of 4 to 8 mm is used as a workpiece to be welded (23), and is fixed on a traveling mechanism (24) of a welding system, and an arc welding gun (21) and a laser head (22) are fixed on a test platform (28) via a welding gun bracket (27) and a laser head bracket (29); Step 2: Adjust the imaging magnification ratio; ensure that the X-ray generating system (1), the molten pool area on the workpiece to be welded (23) and the center of the X-ray imaging system (3) are located on the same axis, control the primary imaging ratio by the distance between the X-ray generating system (1) and the workpiece to be welded (23) (source-object distance d1) and the distance between the workpiece to be welded (23) and the image intensifier input screen (32) (object-image distance d2), and control the secondary imaging ratio by adjusting the focal length of the high-speed camera lens; Step 3: Set system parameters; set the moving speed of the walking mechanism; set the arc welding machine current value, laser output power value and other welding parameters; set the X-ray tube current, tube voltage and focal size; set the high-speed camera shooting frame rate, exposure time and shooting time; Step 4: After the parameter adjustment is completed, the X-ray generation system (1) and the X-ray imaging system (3) are turned on, and welding is performed after the system is stable, and a high-speed camera (34) is used to take real-time photos of the welding molten pool displayed on the image intensifier output screen (33); Step 5: Perform image processing on the captured images and videos, and distinguish and extract the pores in the molten pool by increasing the contrast and binarization, so as to monitor the dynamic behavior of welding pores.

Images