MAG welding pool infrared temperature measurement scanning device and method based on galvanometer system

Abstract

The invention discloses an MAG welding pool infrared temperature measurement scanning device and method based on a galvanometer system, and belongs to the technical field of non-contact MAG welding pool temperature measurement. The device comprises a welding unit, an infrared thermometer, a high-precision galvanometer unit, a data processing unit and a calibration unit. Firstly, integrated installation and optical axis calibration of the infrared thermometer and the high-precision galvanometer unit are achieved through the support; secondly, temperature and position calibration is completed by means of a blackbody furnace and a calibration plate, a high-reflectivity galvanometer is used for driving an infrared temperature measurement light beam to form a linear track, and temperature and angle data are collected; and finally, realizing molten pool temperature field construction through data mapping, interpolation filtering and visual processing to obtain temperature field data. According to the invention, multi-channel array or complex spectrum beam splitting is not needed, and the advantages of high integration and low manufacturing cost are achieved; temperature and position dual calibration is performed through the blackbody furnace and the calibration plate to ensure data accuracy; and after data mapping and interpolation filtering processing, the temperature field is visually presented, and a reliable basis is provided for adjusting welding parameters in real time and improving the welding quality monitoring efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-contact MAG welding molten pool temperature measurement, and relates to an infrared temperature measurement method and device based on continuous scanning of a galvanometer, and in particular to an infrared temperature measurement scanning device and method for a MAG welding molten pool based on a galvanometer system, which is suitable for scenarios where the molten pool temperature field is dynamically monitored during the MAG welding process. Background Art

[0002] During arc welding, real-time monitoring of the molten pool temperature is crucial for welding quality control and process optimization. Traditional temperature measurement methods mainly include thermocouples, single-point infrared thermometers, and infrared thermal imagers. However, these measurement methods have significant limitations when used to dynamically monitor the molten pool temperature field. For example, thermocouples need to directly contact the molten pool or its surrounding area, which results in slow response, easy damage, and interference with the welding process. Single-point infrared thermometers can only measure the temperature of a single point on the welding pool, making it difficult to obtain temperature field distribution information. High-resolution infrared thermal imagers are relatively expensive, and their size and weight are much larger than single-point infrared thermometers. They are difficult to integrate compactly with equipment such as welding gun heads, and place higher demands on on-site space and installation structures.

[0003] To overcome these shortcomings, existing technologies attempt to measure the melt pool temperature field using multi-point infrared temperature measurement arrays or multi-channel spectrometer systems. However, these solutions are often bulky, costly, require multiple signal channels, and require complex calibration. Furthermore, they struggle to meet the requirements for high-speed scanning and high-resolution temperature measurement. Therefore, achieving dynamic measurement of the MAG weld pool temperature field while maintaining instrument miniaturization and high-speed response has become a pressing technical challenge.

[0004] The prior art document, "Design and Experimental Study of an Infrared Temperature Measurement Laser Tin Wire Soldering System," proposes an infrared temperature measurement laser tin wire soldering system. This system uses an infrared thermometer and a spectroscopic system to monitor the temperature of the solder joint during the soldering process. Optical design software simulates and analyzes the propagation paths of the laser beam and infrared temperature measurement beam, verifying the feasibility of the optical system and analyzing the basic characteristics of the output beam. However, the device uses two beam splitters and a total reflection mirror to implement the optical path system design, resulting in a large size and limitations. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention proposes an infrared temperature measurement device and method based on one-dimensional galvanometer line scanning. By using a high-speed galvanometer to drive the single-point temperature measurement beam of the infrared thermometer into a linear scanning temperature measurement beam, the temperature field of the welding pool can be measured quickly, continuously and with high precision, meeting the real-time online monitoring requirements of the MAG welding pool temperature field and significantly improving the welding quality monitoring efficiency.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A MAG welding pool infrared temperature measurement and scanning device based on a galvanometer system, the scanning device includes a welding unit, an infrared thermometer 8, a high-precision galvanometer unit, a data processing unit, a calibration unit part, and a bracket 9. Specifically:

[0008] The welding unit includes a linear module 1, a welding plate 2, a welding gun 3, a slide 4, and a frame. The main body of the frame is a door-shaped structure, including a top transverse beam and longitudinal beam structures on both sides. The bottom of the longitudinal beam structure is installed on the linear module 1, and the linear module 1 drives the frame to reciprocate. The top of the welding gun 3 is fixed to the transverse beam of the frame, and the welding gun 3 can reciprocate on the transverse beam. The bottom of the welding gun 3 is located above the welding plate 2, and the welding gun 3 forms a molten pool 5 on the surface of the welding plate 2. The slide 4 is located below the transverse beam of the frame and is fixed to the bottom workbench and can reciprocate longitudinally. The welding plate 2 is fixed on the slide 4, and the welding position is adjusted by the reciprocating motion of the slide 4.

[0009] The main body of the bracket 9 is two cross-arranged rod-shaped structures, the end of one rod is slidably mounted on the transverse beam of the frame through a linear module 1, which plays a fixing role; the intersection of the two rods is rotatable; the end of the second rod is installed with a high-reflectivity galvanometer 7 and an infrared thermometer 8, which are located obliquely above the molten pool 5.

[0010] The infrared thermometer 8 is used to receive infrared radiation 6 emitted from the surface of the molten pool 5 and convert it into digital temperature data. The infrared thermometer 8 has high sampling frequency and low noise characteristics, ensuring accurate capture of temperature changes during rapid scanning.

[0011] The high-precision galvanometer unit is used to reflect infrared radiation 6 from different locations on the molten pool 5 to the infrared thermometer 8, enabling the acquisition of temperature signals from multiple locations on the molten pool 5. It comprises a high-resolution driver, a high-reflectivity galvanometer 7, and a synchronization control unit. The high-precision galvanometer unit can adjust the scanning range and speed of the high-reflectivity galvanometer 7 according to different welding conditions, achieving full coverage of molten pools 5 of varying widths. The high-reflectivity galvanometer 7 utilizes an analog signal-driven one-dimensional galvanometer. The reflective surface is constructed from high-purity quartz glass and coated with a high-reflectivity gold film to reduce energy loss and enhance the strength and stability of the temperature measurement signal. The high-reflectivity galvanometer 7 is connected to the high-resolution driver via a data cable. The synchronization control unit is connected to the high-resolution driver and the infrared thermometer 8, respectively, to synchronize the control of the high-reflectivity galvanometer 7 and the infrared thermometer 8. During the welding process, the welding plate 2 remains stationary on the slide 4, while the high-reflectivity galvanometer 7 and the infrared thermometer 8 move linearly with the welding torch 3 via the linear module 1.

[0012] The calibration unit comprises a blackbody furnace and a calibration plate. The blackbody furnace is located directly in front of the high-reflectivity galvanometer 7 and infrared thermometer 8, and the calibration plate is located above the welding plate 2. The calibration unit is used to eliminate the loss of infrared radiation from the molten pool 5 after reflection from the high-reflectivity galvanometer 7, as well as the effect of the high-reflectivity galvanometer's own radiation on infrared temperature measurement. It also corrects the deviation between the set position and the actual position of the scanning spot 10 in the scanning optical path. During temperature calibration, the infrared thermometer 8 is aligned with the blackbody furnace cavity to collect the internal temperature of the blackbody furnace. During position calibration, the calibration plate is fixedly placed above the welding plate 2, and the collimated laser emitted by the infrared thermometer 8 is aligned with the specified corner point of the calibration plate.

[0013] The data processing unit consists of a computer and data processing software. The computer is connected to the synchronization control unit via a data cable, receives the angle information of the galvanometer control unit and the temperature data collected by the infrared thermometer, and uses the geometric mapping relationship in the optical design to accurately convert the spot position corresponding to each scanning angle into the spatial coordinates on the molten pool plane.

[0014] Furthermore, in order to facilitate rapid on-site installation and precise alignment, the bracket 9 has a six-degree-of-freedom pitch fine-tuning mechanism, which can be used to calibrate the optical axis with the help of the collimated laser in the infrared thermometer 7. After completion, it is ensured that the scanning start and end positions of the galvanometer 7 completely coincide with the calibration range, thereby achieving accurate positioning.

[0015] A galvanometer-based infrared temperature scanning method for a MAG welding melt pool is implemented based on the aforementioned MAG welding melt pool infrared temperature scanning device. First, a bracket 9 is used to integrate the infrared thermometer 8 and the high-precision galvanometer unit, and the optical axis is aligned to ensure that the scanning optical path accurately covers the melt pool area. Second, a blackbody furnace and a calibration plate are used to complete temperature and position calibration to eliminate measurement errors. Third, during the welding process, a high-reflectivity galvanometer 7 is used to scan back and forth at high speed, driving the infrared temperature measurement beam to form a linear trajectory, and simultaneously collecting temperature and angle data. Finally, the melt pool temperature field is constructed through data mapping, interpolation filtering, and visualization processing to obtain melt pool temperature field data during the MAG welding process. Specifically, the following steps are included:

[0016] Step 1: Install and adjust the infrared temperature scanning device;

[0017] Step 1.1. First, place the reflective surface of the high-reflectivity galvanometer 7 at the focal position of the outgoing light path of the infrared thermometer 8 through the bracket 9 with six-degree-of-freedom adjustment function, and accurately set the angle θ = 45° between the plane of the reflective surface of the high-reflectivity galvanometer 7 and the temperature measurement optical axis of the infrared thermometer 8 to obtain the optimal scanning area.

[0018] Step 1.2. Secondly, use the calibration laser of the infrared thermometer 8 to position the initial light spot generated by the calibration laser of the infrared thermometer 8 at the center of the welding position of the welding plate 2; when the deflection angle of the high-reflectivity galvanometer 7 is 0°, confirm by observing the visible light spot that it falls exactly at the center of the scanning line, thereby ensuring that the first temperature value collected by the infrared thermometer 8 at the beginning of welding corresponds to the temperature at the center of the molten pool 5, completing the preliminary installation.

[0019] Finally, in step 1.3, the high-reflectivity galvanometer mirror 7 is driven to deflect to a maximum deflection angle of ±θmax, and the actual positions of the two ends of the scan line are accurately measured. The measurement results are compared with the theoretically calculated values ​​to ensure that the scanning area completely covers the target molten pool 5 area without missing or exceeding the area, completing the final adjustment. The maximum deflection angle is the maximum angle that the high-reflectivity galvanometer mirror 7 can deflect. The theoretically calculated value is obtained from the trigonometric relationship between the maximum deflection angle and the distance from the center of the reflective surface of the galvanometer mirror 7 to the initial position of the light spot.

[0020] Step 2: Measurement system calibration;

[0021] In step 2.1, a blackbody furnace with a temperature control accuracy of ±0.5°C is used as a calibration heat source. Multiple temperature calibration points are set. At each temperature point, a static measurement is performed using a high-reflectivity galvanometer 7 and an infrared thermometer 8 for 10 seconds to obtain stable temperature data.

[0022] Step 2.2, secondly, at each calibration temperature point, collect 10 sets of original temperature data and pair them with the nominal temperature of each temperature point set by the blackbody furnace.

[0023] Step 2.3, finally, the collected temperature data is fitted with the blackbody furnace nominal temperature data using the least squares method to establish a quadratic correction model.

[0024] Step 2.4: To ensure the position correspondence accuracy during data processing, establish a geometric mapping relationship between the set angle of the high-reflectivity galvanometer 7 during measurement and the actual spatial position of the scanning spot 10. Correct the position error between the ideal position and the actual position of the scanning spot 10 in the scanning light path, eliminate the influence of the galvanometer rotation angle error on the data reconstruction accuracy, and calibrate the position accuracy after temperature calibration. The details are as follows:

[0025] First, a calibration plate with 10 equally spaced graduations, spaced 1 mm apart, was placed on the scanning plane of welding plate 2. This calibration plate was used to establish a mapping relationship between angles and spatial positions. Next, an infrared temperature scanning device was used to scan each graduation on the calibration plate, recording the set of scan angles and their corresponding coordinate positions. Finally, the least squares method was used to fit the relationship between angles and positions, establishing a mapping function and obtaining a geometric mapping relationship.

[0026] Step 3, molten pool temperature data collection;

[0027] Step 3.1: First, after the welding process is started, the synchronous control unit sends a trigger signal to the infrared thermometer 8 and the high-resolution driver simultaneously. From the moment of triggering, the infrared thermometer 8 records the timestamp and the corresponding temperature value at a sampling frequency of ≥16.7Hz, forming the time t-temperature Ti data. From the moment of triggering, the high-resolution driver outputs an analog drive signal to the high-reflectivity galvanometer 7, controlling the high-reflectivity galvanometer 7 to generate deflection motion according to a predetermined scanning strategy, synchronously recording the timestamp and the current deflection angle, forming the time t data and the corresponding deflection angle θ. i data.

[0028] Step 3.2: Next, the high-reflectivity galvanometer 7, driven by a high-resolution driver, oscillates periodically at a fixed angle and frequency (adjusted based on the molten pool width and other working conditions) set by the synchronization control unit, transforming the single-point acquisition optical path of the infrared thermometer 8 into a linear scanning optical path. During a complete scanning cycle, the deflection angle θ of the high-reflectivity galvanometer 7 changes according to the inverse tangent function, ensuring that the scanning spot 10 maintains a uniform motion along the scanning path. The angle θ of the high-reflectivity galvanometer 7 is simultaneously recorded. i —The position x of the scanning spot 10 i Mapping relationship.

[0029] Step 4: Construct the melt pool temperature field data

[0030] Step 4.1: First, the data processing unit processes the time t data and the corresponding deflection angle θ provided by the synchronization control unit in step 3.1. i The data and the time t-temperature T obtained by the infrared thermometer in step 3.1 i Data, establish the scanning angle θ i With temperature data T i The mapping relationship.

[0031] Step 4.2, secondly, the angle θ of the high reflectivity galvanometer 7 obtained by the high precision galvanometer unit in step 3.2 is i —The position x of the scanning spot 10 i Mapping relationship, the temperature value T of each sampling pointi Mapped to the corresponding spatial position x i , get discrete position-temperature data pairs (x i ,T i ).

[0032] Step 4.3: Generate the temperature field visualization interface. Specifically:

[0033] In order to obtain a continuous and smooth temperature field distribution curve, firstly i Discrete position-temperature data pairs (x i ,T i ) applies the cubic spline interpolation algorithm to construct a continuous function T(x) that shows how the temperature changes with the spatial coordinates. Secondly, to further eliminate high-frequency noise that may be introduced during the interpolation process and ensure the reliability of subsequent temperature gradient calculations and pseudo-color visualization, a one-dimensional Gaussian filter is applied to the interpolated continuous function T(x), ultimately obtaining a smooth temperature distribution curve along the target scanning line. Finally, based on the obtained temperature curve and the calibration coefficients, a temperature field visualization interface is generated.

[0034] Furthermore, the temperature field visualization interface includes:

[0035] Real-time curve chart: With spatial position x as the horizontal coordinate and temperature T(x) as the vertical coordinate, it dynamically displays the temperature change trend along the scan line;

[0036] Pseudo-color strips: The temperature curve T(x) is colored according to a predefined temperature-color mapping (such as an RGB gradient from blue to red) to achieve intuitive visualization of the temperature gradient.

[0037] The beneficial effects of the present invention are:

[0038] (1) The present invention only adds a high-reflectivity galvanometer and a synchronous control unit to the single-point thermometer, and combines precise adjustment and scanning strategies. It does not require a multi-channel array or complex spectral beam splitting, and has the advantages of high integration and low manufacturing cost.

[0039] (2) The present invention uses a blackbody furnace and a calibration plate to perform dual calibration of temperature and position, eliminating measurement errors and ensuring data accuracy;

[0040] (3) The present invention visualizes the temperature field after data mapping and interpolation filtering, providing a reliable basis for real-time adjustment of welding parameters and improvement of welding quality monitoring efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the overall architecture of the galvanometer-infrared system designed in the present invention;

[0042] Figure 2This is a schematic diagram of the infrared spot scanning path designed by the present invention;

[0043] Figure 3 is a galvanometer angle control curve diagram in the present invention;

[0044] Figure 4 This is the control logic diagram of the infrared-galvanometer system designed by the present invention;

[0045] Figure 5 It is a system calibration flow chart designed by the present invention;

[0046] Figure 6 This is a flow chart of the method for constructing the molten pool temperature field designed by the present invention;

[0047] In the figure: 1 linear module; 2 welding plate; 3 welding gun; 4 slide; 5 molten pool; 6 infrared radiation; 7 high reflectivity galvanometer; 8 infrared thermometer; 9 bracket; 10 scanning spot. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

[0049] The overall structure of this embodiment is shown as follows Figure 1 As shown, the scanning device includes a welding unit, an infrared thermometer 8, a high-precision galvanometer unit, a data processing unit, a calibration unit, and a bracket 9.

[0050] The welding unit includes a linear module 1, a welding plate 2, a welding gun 3, a slide 4, and a frame. The main body of the frame is a door-shaped structure, including a top transverse beam and longitudinal beam structures on both sides. The bottom of the longitudinal beam structure is installed on the linear module 1, and the linear module 1 drives the frame to reciprocate. The top of the welding gun 3 is fixed to the transverse beam of the frame, and the welding gun 3 can reciprocate on the transverse beam. The bottom of the welding gun 3 is located above the welding plate 2, and a molten pool 5 is formed on the surface of the welding plate 2 through the welding gun 3. The slide 4 is located below the transverse beam of the frame and is fixed to the bottom workbench and can reciprocate longitudinally. The welding plate 2 is fixed to the slide 4, and the welding position is adjusted by the reciprocating motion of the slide 4.

[0051] The main body of the bracket 9 is two cross-arranged rod-shaped structures, the end of one rod is slidably mounted on the transverse beam of the frame through a linear module 1, which plays a fixing role; the intersection of the two rods is rotatable; the end of the second rod is installed with a high-reflectivity galvanometer 7 and an infrared thermometer 8, which are located obliquely above the molten pool 5.

[0052] The infrared thermometer 8 is a non-contact sensor with a spectral response center wavelength of 5 μm, a temperature resolution of ≤1 °C, and a sampling frequency of ≥16.7 Hz. It can obtain real-time molten pool temperature data with high time resolution and high temperature resolution during the welding process, and ensure the accuracy and reliability of the temperature measurement data.

[0053] The high-precision galvanometer unit is used to reflect infrared radiation 6 from different locations on the molten pool 5 to the infrared thermometer 8, enabling the acquisition of temperature signals from multiple locations on the molten pool 5. It includes a high-resolution driver, a high-reflectivity galvanometer 7, and a synchronization control unit. The high-precision galvanometer unit can adjust the scanning range and speed of the high-reflectivity galvanometer 7 according to different welding conditions, achieving full coverage of molten pools 5 of varying widths. The high-reflectivity galvanometer 7 utilizes an analog signal-driven one-dimensional galvanometer with a minimum step size (0.1°) response time of less than 0.4 ms, fully meeting the high-responsiveness requirements of dynamic tracking in high-speed welding scenarios. The galvanometer's repeatability error is controlled to ≤3 μrad, ensuring that each scan returns to the same angular position, enabling high-precision temperature field reconstruction. The galvanometer's deflection angle range is ±11.5°, and at a standard working distance of 450 mm, the scan line length can be adjusted from 0 to 180 mm, enabling flexible coverage of welding areas from small to large. The reflective surface of the galvanometer is made of high-purity quartz glass and coated with a high-reflectivity gold film. The reflectivity of the infrared light in the 5-14 μm band is ≥98%, which minimizes energy loss and improves the intensity and stability of the temperature measurement signal.

[0054] The high-reflectivity galvanometer 7 is connected to a high-resolution driver via a data cable. The synchronization control unit is connected to the high-resolution driver and the infrared thermometer 8, respectively, to achieve synchronized control of the high-reflectivity galvanometer 7 and the infrared thermometer 8. During the welding process, the welding plate 2 remains stationary on the slide 4, while the high-reflectivity galvanometer 7 and the infrared thermometer 8 move linearly with the welding gun 3 through the linear module 1. During the welding process, the welding plate 2 remains stationary on the slide 4, while the galvanometer assembly 7 and the infrared thermometer 8 move linearly with the welding gun 3 through the linear module 1.

[0055] The calibration unit comprises a blackbody furnace and a calibration plate. The blackbody furnace is located directly in front of the high-reflectivity galvanometer 7 and infrared thermometer 8, and the calibration plate is located above the welding plate 2. The calibration unit is used to eliminate the loss of infrared radiation from the molten pool 5 after reflection from the high-reflectivity galvanometer, as well as the effect of the high-reflectivity galvanometer's own radiation on infrared temperature measurement. It also corrects the deviation between the set position and the actual position of the scanning spot 10 in the scanning optical path. During temperature calibration, the infrared thermometer 8 is aligned with the blackbody furnace cavity to collect the internal temperature of the blackbody furnace. During position calibration, the calibration plate is fixedly placed above the welding plate 2, and the collimated laser emitted by the infrared thermometer 8 is aimed at a specified corner point on the calibration plate.

[0056] The data processing unit consists of a computer and data processing software. The computer is connected to the synchronization control unit via a data cable, receives the angle information of the galvanometer control unit and the temperature data collected by the infrared thermometer, and uses the geometric mapping relationship in the optical design to accurately convert the spot position corresponding to each scanning angle into the spatial coordinates on the molten pool plane.

[0057] Furthermore, in order to facilitate rapid on-site installation and precise alignment, the bracket 9 has a six-degree-of-freedom pitch fine-tuning mechanism, which can be used to calibrate the optical axis with the help of the collimated laser in the infrared thermometer 7. After completion, it is ensured that the scanning start and end positions of the galvanometer 7 completely coincide with the calibration range, thereby achieving accurate positioning.

[0058] A galvanometer-based infrared temperature scanning method for a MAG welding melt pool is implemented based on the aforementioned MAG welding melt pool infrared temperature scanning device. First, a bracket 9 is used to integrate the infrared thermometer 8 and the high-precision galvanometer unit, and the optical axis is aligned to ensure that the scanning optical path accurately covers the melt pool area. Second, a blackbody furnace and a calibration plate are used to complete temperature and position calibration to eliminate measurement errors. Third, during the welding process, a high-reflectivity galvanometer 7 is used to scan back and forth at high speed, driving the infrared temperature measurement beam to form a linear trajectory, and simultaneously collecting temperature and angle data. Finally, the melt pool temperature field is constructed through data mapping, interpolation filtering, and visualization processing to obtain melt pool temperature field data during the MAG welding process. Specifically, the following steps are included:

[0059] Step 1: Install and adjust the infrared temperature scanning device

[0060] Step 1.1. First, place the reflective surface of the high-reflectivity galvanometer 7 at the focal position of the outgoing light path of the infrared thermometer 8 through the bracket 9 with six-degree-of-freedom adjustment function, and accurately set the angle θ = 45° between the plane of the reflective surface of the high-reflectivity galvanometer 7 and the temperature measurement optical axis of the infrared thermometer 8 to obtain the optimal scanning area.

[0061] Step 1.2. Secondly, use the calibration laser of the infrared thermometer 8 to position the initial light spot generated by the calibration laser of the infrared thermometer 8 at the center of the welding position of the welding plate 2; when the deflection angle of the high-reflectivity galvanometer 7 is 0°, confirm by observing the visible light spot that it falls exactly at the center of the scanning line, thereby ensuring that the first temperature value collected by the infrared thermometer 8 at the beginning of welding corresponds to the temperature at the center of the molten pool 5, completing the preliminary installation.

[0062] Finally, in step 1.3, the high-reflectivity galvanometer mirror 7 is driven to deflect to a maximum deflection angle of ±θmax, and the actual positions of the two ends of the scan line are accurately measured. The measurement results are compared with the theoretically calculated values ​​to ensure that the scanning area completely covers the target molten pool 5 area without missing or exceeding the area, completing the final adjustment. The maximum deflection angle is the maximum angle that the high-reflectivity galvanometer mirror 7 can deflect. The theoretically calculated value is obtained from the trigonometric relationship between the maximum deflection angle and the distance from the center of the reflective surface of the galvanometer mirror 7 to the initial position of the light spot.

[0063] Infrared temperature measurement light 6 is split into two segments before and after being refracted by the galvanometer. The optimal detection distance of infrared thermometer 8 is 450 mm. The center of galvanometer 7 is 120 mm from the center of the infrared thermometer 8's light emission. To ensure that the temperature measurement light beam 6 is accurately focused on the surface of the molten pool 5 after reflection from the galvanometer 7 and to maintain an effective measurement distance of 450 mm between the infrared thermometer 8 and the molten pool 5, the distance from the center of the galvanometer 7's reflective surface to the surface of the molten pool 5 should be precisely maintained at 330 mm. In this way, the temperature measurement light path, emitting from infrared thermometer 8, first reaches the reflective surface of galvanometer 7 and then refracts to the surface of the molten pool 5. The total distance traveled is 450 mm, meeting the instrument's measurement requirements.

[0064] Step 2: Measurement system calibration

[0065] Step 2.1. First, use a blackbody furnace with a temperature control accuracy of ±0.5°C as the calibration heat source. Set multiple temperature calibration points: 500°C, 700°C, 900°C, 1100°C, 1300°C, 1500°C, 1700°C, 1900°C, 2100°C, 2300°C, and 2500°C. At each temperature point, perform static measurements using a high-reflectivity galvanometer 7 and an infrared thermometer 8 for 10 seconds to obtain stable temperature data.

[0066] Step 2.2, secondly, at each calibration temperature point, collect 10 sets of raw temperature data and pair them with the nominal temperature set by the blackbody furnace.

[0067] Step 2.3, finally, the collected temperature data is fitted with the blackbody furnace nominal temperature data using the least squares method to establish a quadratic correction model.

[0068] Step 2.4: To ensure the position correspondence accuracy during data processing, establish a geometric mapping relationship between the set angle of the high-reflectivity galvanometer 7 during measurement and the actual spatial position of the scanning spot 10. Correct the position error between the ideal position and the actual position of the scanning spot 10 in the scanning light path, eliminate the influence of the galvanometer rotation angle error on the data reconstruction accuracy, and calibrate the position accuracy after temperature calibration. The details are as follows:

[0069] First, a calibration plate with 10 equally spaced graduations, spaced 1 mm apart, was placed on the scanning plane of welding plate 2. This calibration plate was used to establish a mapping relationship between angles and spatial positions. Next, an infrared temperature scanning device was used to scan each graduation on the calibration plate, recording the set of scan angles and their corresponding coordinate positions. Finally, the least squares method was used to fit the relationship between angles and positions, establishing a mapping function and obtaining a geometric mapping relationship.

[0070] Step 3: Melt pool temperature data collection

[0071] Step 3.1: First, after the welding process is started, the synchronous control unit sends a trigger signal to the infrared thermometer 8 and the high-resolution driver simultaneously. From the moment of triggering, the infrared thermometer 8 records the timestamp and the corresponding temperature value at a sampling frequency of ≥16.7Hz, forming the time t-temperature Ti data. From the moment of triggering, the high-resolution driver outputs an analog drive signal to the high-reflectivity galvanometer 7, controlling the high-reflectivity galvanometer 7 to generate deflection motion according to a predetermined scanning strategy, synchronously recording the timestamp and the current deflection angle, forming the time t data and the corresponding deflection angle θ. i data.

[0072] Step 3.2: Next, the high-reflectivity galvanometer 7, driven by a high-resolution driver, oscillates periodically at a fixed angle and frequency (adjusted based on the molten pool width and other working conditions) set by the synchronization control unit, transforming the single-point acquisition optical path of the infrared thermometer 8 into a linear scanning optical path. During a complete scanning cycle, the deflection angle θ of the high-reflectivity galvanometer 7 changes according to the inverse tangent function, ensuring that the scanning spot 10 maintains a uniform motion along the scanning path. The angle θ of the high-reflectivity galvanometer 7 is simultaneously recorded. i —The position x of the scanning spot 10 i Mapping relationship.

[0073] In order to achieve complete coverage of the MAG welding molten pool by the temperature measurement scanning light, the scanning angle-displacement geometric mapping relationship is constructed to achieve the following Figure 2 The scanning path for complete coverage of the molten pool is shown in the figure. In a typical arc welding process, the actual measured width of the molten pool 5 is about 9 mm. In order to completely cover the molten pool 5 area and reserve a margin for edge monitoring, the system sets the effective coverage length of the scanning spot to 9.5 mm, which is 0.5 mm longer than the maximum width of the molten pool 5 to avoid measurement blind spots caused by workpiece vibration or dynamic deformation of the molten pool. The coverage range of the scanning spot 10 is precisely controlled by the deflection angle of the galvanometer 7: when the total length of the scanning line is 9.5 mm, the 7.5 mm spot needs to be offset by 1 mm to both sides of the scanning center line (that is, a total offset of 2 mm). At this time, the mechanical deflection angle θ of the galvanometer 7 can be calculated by trigonometric function:

[0074] (1)

[0075] in, is the offset distance of the scanning spot 10, and L is the distance from the center of the reflecting surface of the high-reflectivity galvanometer 7 to the surface of the molten pool 5.

[0076] Specifically, the deflection angle range of the high-reflectivity galvanometer 7 is set to −0.17° to +0.17°, which enables the scanning spot 10 to form a scanning line with a length of 9.5 mm on the surface of the molten pool 5, achieving the effect of the scanning light completely covering the temperature field of the entire MAG welding molten pool.

[0077] In order to achieve the coordination of the galvanometer deflection angle and the infrared thermometer sampling time, and to scan the entire molten pool area, the control unit of the high-precision galvanometer unit adopts the following Figure 3 The system is driven by the motion trajectory shown. To achieve smooth temporal variation of the deflection angle of the high-reflectivity galvanometer 7 and simplify back-end data processing and interpolation operations, the system adopts an inverse tangent curve scanning mode in the control strategy of the high-reflectivity galvanometer 7. During a complete scanning cycle, the deflection angle θ of the high-reflectivity galvanometer 7 changes according to the inverse tangent function, ensuring that the scanning spot 10 of the infrared thermometer 8 maintains a uniform motion along the scanning path. Uniform scanning not only ensures a uniform distribution of spatial sampling points but also simplifies and efficiently facilitates subsequent interpolation calculations, reducing the computational effort.

[0078] In the actual measurement process, the sampling interval Δt of the infrared thermometer 8 is set to 60ms, that is, temperature data is collected every 60ms. To ensure that the movement of the light spot is synchronized with the sampling rhythm, the system needs to make the light spot move along the scanning path Δs≈0.5mm during this time, and the linear scanning speed v is obtained as:

[0079] (2)

[0080] Wherein, Δt is the sampling time interval of the infrared thermometer 8, and Δs is the change distance of the sampling center point of the infrared thermometer 8 within the sampling time interval.

[0081] This speed not only meets the response time requirement of the infrared thermometer 8, but also can complete the continuous scanning of the entire molten pool width while maintaining the temperature measurement accuracy.

[0082] During the time period of 0 to 120 ms when the high reflectivity galvanometer mirror 7 starts to deflect, the high reflectivity galvanometer mirror 7 deflects from 0° to 0.17°. At this time, the relationship between the deflection angle θ of the high reflectivity galvanometer mirror 7 and the time t is:

[0083] (3)

[0084] Wherein, v is the linear scanning speed, and L2 is the distance from the center of the reflecting surface of the high-reflectivity galvanometer 7 to the surface of the molten pool 5.

[0085] Through the optimization of the above-mentioned geometric arrangement and control strategy, the system can perform stable and accurate line scanning measurement of the molten pool temperature field in the high-speed dynamic environment of arc welding.

[0086] Step 4: Construct the melt pool temperature field data

[0087] Step 4.1: First, the data processing unit processes the time t data and the corresponding deflection angle θ provided by the synchronization control unit in step 3.1. i The data and the time t-temperature T obtained by the infrared thermometer in step 3.1 i Data, establish the scanning angle θ i With temperature data T i The mapping relationship.

[0088] Step 4.2, secondly, the angle θ of the high reflectivity galvanometer 7 obtained by the high precision galvanometer unit in step 3.2 is i —The position x of the scanning spot 10 i Mapping relationship, the temperature value T of each sampling point i Mapped to the corresponding spatial position x i , get discrete position-temperature data pairs (x i ,T i ).

[0089] Step 4.3: Generate a temperature field visualization interface. Specifically:

[0090] In order to obtain a continuous and smooth temperature field distribution curve, firstly i Discrete position-temperature data pairs (x i ,T i ) applies the cubic spline interpolation algorithm to construct a continuous function T(x) that shows how the temperature changes with the spatial coordinates. Secondly, to further eliminate high-frequency noise that may be introduced during the interpolation process and ensure the reliability of subsequent temperature gradient calculations and pseudo-color visualization, a one-dimensional Gaussian filter is applied to the interpolated continuous function T(x), ultimately obtaining a smooth temperature distribution curve along the target scanning line. Finally, based on the obtained temperature curve and the calibration coefficients, a temperature field visualization interface is generated.

[0091] Furthermore, the temperature field visualization interface includes:

[0092] Real-time curve chart: With spatial position x as the horizontal coordinate and temperature T(x) as the vertical coordinate, it dynamically displays the temperature change trend along the scan line;

[0093] Pseudo-color strips: The temperature curve T(x) is colored according to a predefined temperature-color mapping (such as an RGB gradient from blue to red) to achieve intuitive visualization of the temperature gradient.

[0094] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A MAG welding pool infrared temperature measurement and scanning device based on a galvanometer system, characterized in that: The scanning device includes a welding unit, an infrared thermometer (8), a high-precision galvanometer unit, a data processing unit, a calibration unit, and a bracket (9), specifically: The welding unit comprises a linear module (1), a welding plate (2), a welding gun (3), a slide (4), and a frame; the frame body is a door-shaped structure, comprising a top transverse beam and longitudinal beams on both sides, the longitudinal beams being mounted on the linear module (1), and the linear module (1) driving the frame to reciprocate; the top of the welding gun (3) is mounted on the transverse beam and can reciprocate on the transverse beam, the bottom of the welding gun (3) is located above the welding plate (2), and a molten pool (5) is formed on the surface of the welding plate (2) by the welding gun (3); the slide (4) is located below the transverse beam, fixed on the bottom workbench, and can reciprocate longitudinally; the welding plate (2) is fixed on the slide (4), and the welding position is adjusted by the reciprocating motion of the slide (4); The main body of the bracket (9) is a rod-shaped structure arranged in two crosses, wherein the end of one of the rods is slidably mounted on the transverse beam of the frame through a linear module (1); the intersection of the two rods is rotatable; the end of the second rod is mounted with a high reflectivity galvanometer (7) and an infrared thermometer (8), which are located obliquely above the molten pool (5); The high-precision galvanometer unit is used to reflect infrared radiation at different positions of the molten pool (5) to the infrared thermometer (8), thereby acquiring temperature signals at multiple positions of the molten pool (5), and comprises a high-resolution driver, a high-reflectivity galvanometer (7), and a synchronization control unit; the high-precision galvanometer unit adjusts the scanning range and speed of the high-reflectivity galvanometer (7) according to different welding conditions, thereby achieving full coverage of molten pools (5) of different widths; The calibration unit includes a black body furnace and a calibration plate, the black body furnace is located in front of the high reflectivity galvanometer (7) and the infrared thermometer (8), and the calibration plate is located above the welding plate (2); The data processing unit is connected to the synchronization control unit, receives the angle information of the high-precision galvanometer unit and the temperature data collected by the infrared thermometer (8), and uses the geometric mapping relationship in the optical design to accurately convert the spot position corresponding to each scanning angle into the spatial coordinate on the plane of the molten pool (5).

2. The infrared temperature measurement and scanning device for a MAG welding pool based on a galvanometer system according to claim 1, characterized in that: The infrared thermometer (8) is used to receive infrared radiation (6) emitted from the surface of the molten pool (5) and convert it into digital temperature data; the bracket (9) has a six-degree-of-freedom pitch fine-tuning mechanism, and the optical axis is calibrated by the collimated laser in the infrared thermometer (8). After completion, it is ensured that the scanning start and end positions of the galvanometer 7 completely coincide with the calibration range to achieve accurate positioning.

3. The infrared temperature measurement and scanning device for a MAG welding pool based on a galvanometer system according to claim 1, characterized in that: In the high-precision galvanometer unit, the high-reflectivity galvanometer 7 is an analog signal driven one-dimensional galvanometer, the reflective surface substrate is made of quartz glass, and a high-reflectivity gold film is plated on its surface; the high-reflectivity galvanometer 7 is connected to a high-resolution driver.

4. The infrared temperature measurement and scanning device for a MAG welding pool based on a galvanometer system according to claim 1, characterized in that: The synchronization control unit is connected to a high-resolution driver and an infrared thermometer (8) respectively to achieve synchronous control of the high-reflectivity galvanometer (7) and the infrared thermometer (8); during the welding process, the welding plate (2) is fixed on the slide (4) and remains stationary, and the high-reflectivity galvanometer (7) and the infrared thermometer (8) move linearly along with the welding gun (3) through the linear module (1).

5. The infrared temperature measurement and scanning device for a MAG welding pool based on a galvanometer system according to claim 1, characterized in that: The calibration unit is used to eliminate the loss of infrared radiation from the molten pool (5) after being reflected by the high-reflectivity galvanometer (7) and the influence of the high-reflectivity galvanometer's own radiation on infrared temperature measurement, and to correct the deviation between the set position and the actual position of the scanning light spot (10) in the scanning light path; during temperature calibration, the infrared thermometer (8) is aligned with the blackbody furnace cavity opening to collect the temperature inside the blackbody furnace; during position calibration, the calibration plate is fixedly placed on the welding plate (2), and the collimated laser emitted by the infrared thermometer (8) is aligned with the specified corner point of the calibration plate.

6. A method for infrared temperature measurement and scanning of a MAG welding pool based on a galvanometer system, characterized in that: The infrared temperature measurement scanning device for the MAG welding molten pool is realized based on any one of claims 1-5. First, the infrared thermometer (8) and the high-precision galvanometer unit are integrated and the optical axis is calibrated by a bracket (9) to ensure that the scanning light path accurately covers the molten pool area; secondly, the temperature and position calibration is completed with the help of a blackbody furnace and a calibration plate to eliminate measurement errors; thirdly, during the welding process, the high-reflectivity galvanometer (7) is used to scan back and forth at high speed to drive the infrared temperature measurement beam to form a linear trajectory, and the temperature and angle data are collected synchronously; finally, the molten pool temperature field is constructed through data mapping, interpolation filtering and visualization processing to obtain the molten pool temperature field data during the MAG welding process.

7. The infrared temperature measurement scanning method of a MAG welding pool based on a galvanometer system according to claim 6, characterized in that: The following steps are involved: Step 1: Install and adjust the infrared temperature scanning device; Step 1.1, placing the reflective surface of the high-reflectivity galvanometer (7) at the focal position of the outgoing light path of the infrared thermometer (8) through the bracket (9), and accurately setting the angle θ between the plane of the reflective surface of the high-reflectivity galvanometer (7) and the temperature measurement optical axis of the infrared thermometer (8) to obtain the optimal scanning area; Step 1.2, position the initial light spot generated by the calibration laser of the infrared thermometer (8) at the center of the welding position of the welding plate (2); when the deflection angle of the high reflectivity galvanometer (7) is 0°, the light spot falls on the center of the scanning line, ensuring that the first temperature value collected by the infrared thermometer (8) at the beginning of welding corresponds to the temperature of the center of the molten pool (5), completing the preliminary installation; Step 1.3, drive the high reflectivity galvanometer (7) to deflect to the maximum deflection angle, and accurately measure the actual positions of the two ends of the scanning line, compare the measurement results with the theoretical calculated values, ensure that the scanning area completely covers the target molten pool (5) area, and complete the final adjustment; Step 2: Measurement system calibration; Step 2.1, using a black body furnace as a calibration heat source, setting multiple temperature calibration points, and using a high reflectivity galvanometer (7) and an infrared thermometer (8) to perform static measurement at each temperature point to obtain stable temperature data; Step 2.2, at each calibration temperature point, collect multiple sets of raw temperature data and pair them with the nominal temperature of each temperature point set by the blackbody furnace; Step 2.3, use the least squares method to fit the collected temperature data with the blackbody furnace nominal temperature data to establish a quadratic correction model; Step 2.4, establish the geometric mapping relationship between the set angle of the high reflectivity galvanometer (7) during measurement and the actual spatial position of the scanning spot 10, correct the position error between the ideal position and the actual position of the scanning spot 10 in the scanning light path, eliminate the influence of the galvanometer rotation angle error on the data reconstruction accuracy, and calibrate the position accuracy after temperature calibration. Step 3, collecting molten pool temperature data; Step 3.1, after the welding process is started, the synchronous control unit sends a trigger signal to the infrared thermometer (8) and the high-resolution driver at the same time; the infrared thermometer (8) records the timestamp and the corresponding temperature value from the trigger moment, forming the time t-temperature Ti data; the high-resolution driver outputs an analog drive signal to the high-reflectivity galvanometer (7) from the trigger moment, controls the high-reflectivity galvanometer (7) to generate a deflection motion according to a predetermined scanning strategy, and synchronously records the timestamp and the current deflection angle, forming the time t data and the corresponding deflection angle θ. i data; In step 3.2, the high-reflectivity galvanometer (7) is driven by a high-resolution driver to perform periodic swings at a fixed angle and a fixed frequency set by the synchronization control unit, thereby converting the single-point acquisition optical path of the infrared thermometer (8) into a linear scanning optical path. In a complete scanning cycle, the deflection angle θ of the high-reflectivity galvanometer (7) changes according to the inverse tangent function, so that the scanning spot 10 maintains a uniform motion on the scanning path, and the angle θ of the high-reflectivity galvanometer (7) is recorded at the same time. i —The position x of the scanning spot 10 i Mapping relationship; Step 4: Construct the melt pool temperature field data Step 4.1: The data processing unit calculates the time t data and the corresponding deflection angle θ provided by the synchronization control unit in step 3.

1. i The data and the time t-temperature T obtained by the infrared thermometer in step 3.1 i Data, establish the scanning angle θ i With temperature data T i The mapping relationship; Step 4.2, the angle θ of the high reflectivity galvanometer (7) obtained by the high precision galvanometer unit in step 3.2 i —The position x of the scanning spot 10 i Mapping relationship, the temperature value T of each sampling point i Mapped to the corresponding spatial position x i , get discrete position-temperature data pairs (x i ,T i ); Step 4.3: Generate the temperature field visualization interface.

8. The infrared temperature measurement and scanning method of a MAG welding pool based on a galvanometer system according to claim 7, characterized in that: In step 1: In step 1.1, the angle θ=45°; In step 1.3, the maximum deflection angle is the maximum angle of deflection of the high reflectivity galvanometer (7); the theoretical calculated value is obtained by the trigonometric function relationship between the maximum deflection angle and the distance from the center of the reflective surface of the galvanometer 7 to the initial position of the light spot.

9. The infrared temperature measurement and scanning method of a MAG welding pool based on a galvanometer system according to claim 7, characterized in that: In step 2: In step 2.1, a blackbody furnace with a temperature control accuracy of ±0.5°C is used as the calibration heat source; The specific steps of step 2.4 are as follows: first, a calibration plate with 10 equally spaced scales is placed on the scanning plane of the welding plate (2), and the scale spacing is 1 mm. The calibration plate is used to establish a mapping relationship between angles and spatial positions; second, an infrared temperature scanning device is used to scan each scale position on the calibration plate, and the scanning angle set and the actual coordinate position set corresponding to each scale are recorded; finally, the relationship between the angle and the position is fitted, a mapping function is established, and a geometric mapping relationship is obtained.

10. The infrared temperature measurement scanning method of a MAG welding pool based on a galvanometer system according to claim 7, characterized in that: The step 4.3 is as follows: first, the spatial position x i Discrete position-temperature data pairs (x i ,T i ) applies the cubic spline interpolation algorithm to construct a continuous function T(x) that shows how the temperature changes with the spatial coordinates. Secondly, a one-dimensional Gaussian filter is applied to the interpolated continuous function T(x) to obtain a smooth temperature distribution curve on the target scanning line. Finally, a temperature field visualization interface is generated based on the obtained temperature curve and the calibration coefficient. The temperature field visualization interface includes a real-time curve graph and a pseudo-color strip.

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