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CN-122007621-A - Laser welding detection device and method based on keyhole thermal radiation scanning

CN122007621ACN 122007621 ACN122007621 ACN 122007621ACN-122007621-A

Abstract

The invention provides a laser welding detection device and method based on keyhole thermal radiation scanning, wherein the device comprises a welding mechanism and a detection mechanism, the welding mechanism comprises a welding light source, a welding optical fiber, a welding collimating lens group, a laser beam combining lens, a laser welding vibrating lens and a field lens, welding laser emitted by the welding light source sequentially passes through the welding optical fiber, the welding collimating lens group, the laser beam combining lens, the laser welding vibrating lens and the field lens and then reaches a processing point on a processing workpiece, and the detection mechanism emits detection laser to scan and detect the processing workpiece. The invention can rapidly and accurately detect the welding penetration of the welding seam.

Inventors

  • ZHOU ZHIKAI
  • Kong Ruiming
  • WANG ANXIN
  • XU HAIJIAN

Assignees

  • 苏州卡门哈斯激光技术有限责任公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (9)

  1. 1. The laser welding detection device based on keyhole thermal radiation scanning comprises a welding mechanism, a detection mechanism, a data acquisition module, a processing module and a display module, and is characterized in that the welding mechanism comprises a welding light source, a welding optical fiber (1), a welding collimating lens group (2), a laser beam combining lens (3), a laser welding vibrating lens (4) and a field lens (5), and welding laser emitted by the welding light source sequentially passes through the welding optical fiber (1), the welding collimating lens group (2), the laser beam combining lens (3), the laser welding vibrating lens (4) and the field lens (5) and then reaches a processing workpiece (7) to form a processing point (6); The detection mechanism comprises a detection light source (22), a transmission optical fiber (21), a polarization isolator (20), a light splitting optical fiber coupler (16), a detection assembly, a reference assembly and a processing assembly, wherein the detection assembly comprises a detection optical fiber (11), a detection collimating mirror group (10), a detection vibrating mirror (9) and a detection reflecting mirror (8), laser emitted by the detection light source (22) passes through the transmission optical fiber (21) and the polarization isolator (20) and then reaches the light splitting optical fiber coupler (16) to be divided into detection laser and reference laser, the detection laser sequentially passes through the detection optical fiber (11), the detection collimating mirror group (10), the detection vibrating mirror (9) and the detection reflecting mirror (8) and then is reflected to the laser beam combining mirror (3), the detection laser and the welding laser coaxially enter the laser welding vibrating mirror (4) and form a detection point which coincides with a processing point (6) on a processing workpiece (7), and the detection laser is reflected by the surface of the processing workpiece (7) and returns to the light splitting optical fiber coupler (16) according to an original light path; The reference component comprises a reference optical fiber (12), a reference collimating lens group (13), a reference focusing lens group (14) and a reflecting golden mirror (15), wherein the reference laser sequentially passes through the reference optical fiber (12), the reference collimating lens group (13) and the reference focusing lens group (14) and then reaches the reflecting golden mirror (15) to be reflected, the reference laser returns to a light splitting optical fiber coupler (16) according to an original light path, detection laser and the reference laser in the light splitting optical fiber coupler (16) interfere to form interference laser, the processing component comprises a processing optical fiber (17), a spectrometer (18) and a camera (19), the interference laser enters the spectrometer (18) through the processing optical fiber (17) to obtain an interference spectrum, the camera (19) acquires interference spectrum signals of the interference spectrum, and the data acquisition module is electrically connected with the camera (19) and the processing module, and the processing module is electrically connected with the display module.
  2. 2. The laser welding detection device based on keyhole thermal radiation scanning is characterized in that the detection galvanometer (9) comprises a first detection galvanometer lens (9 b) and a second detection galvanometer lens (9 c), the first detection galvanometer lens (9 b) and the second detection galvanometer lens (9 c) are respectively connected with a first detection motor (9 a) and a second detection motor (9 d), so that the first detection motor (9 a) and the second detection motor (9 d) respectively conduct angle adjustment and swing on the first detection galvanometer lens (9 b) and the second detection galvanometer lens (9 c), detection laser is reflected onto the second detection galvanometer lens (9 c) by the first detection galvanometer lens (9 b) after passing through the detection collimating lens group (10), and the second detection galvanometer lens (9 c) reflects the detection laser onto the detection reflecting mirror (8).
  3. 3. The laser welding detection device based on keyhole thermal radiation scanning is characterized in that the laser welding galvanometer (4) comprises a first welding galvanometer lens (4 b) and a second welding galvanometer lens (4 d), the first welding galvanometer lens (4 b) and the second welding galvanometer lens (4 d) are respectively connected with a first welding motor (4 a) and a second welding motor (4 c), so that the first welding motor (4 a) and the second welding motor (4 c) respectively conduct angle adjustment and swing on the first welding galvanometer lens (4 b) and the second welding galvanometer lens (4 d), and the first welding galvanometer lens (4 b) reflects mixed laser composed of welding laser and detection laser from a self-excitation beam combiner (3) onto the second welding galvanometer lens (4 d), and the second welding galvanometer lens (4 d) reflects the mixed laser onto a field lens (5).
  4. 4. The laser welding detection device based on keyhole thermal radiation scanning as set forth in claim 2, wherein the detection mirror (8) is disposed at an angle of 45 degrees.
  5. 5. The laser welding inspection device based on keyhole thermal radiation scanning as set forth in claim 2, wherein the inspection light source (22) is a super-radiation light emitting diode.
  6. 6. The laser welding detection method based on the keyhole thermal radiation scanning is characterized by adopting the laser welding detection device based on the keyhole thermal radiation scanning as set forth in any one of claims 2-5, and comprises the following steps: S1, operating the welding light source to emit welding laser, and operating the detection light source (22) to emit laser; S2, adjusting the end face height of the detection optical fiber (11), observing the demodulation signal intensity displayed by the display module, and stopping adjusting the end face height of the detection optical fiber (11) when the demodulation signal intensity is maximum, wherein the detection laser focus (25) and the welding laser focus (26) are both arranged on the surface of the processing workpiece (7) at the moment, so that the alignment of detection laser and welding laser in the Z direction is realized; S3, operating the welding light source to emit pulse laser to beat a welding spot (23) on the surface of a machined workpiece (7), operating the detection vibrating mirror (9), and enabling the first detection motor (9 a) and the second detection motor (9 d) to swing the first detection vibrating mirror lens (9 b) and the second detection vibrating mirror lens (9 c) respectively so as to change the detection position of the detection laser to scan the welding spot (23); S4, demodulating the interference spectrum signal by using the processing module to obtain reflectivity and height information of a welding spot area, and displaying an image of the welding spot (23) on the display module, wherein the detection galvanometer (9) is operated to adjust angles of a first detection galvanometer lens (9 b) and a second detection galvanometer lens (9 c) so that the center of a field of view of the detection galvanometer (9) is offset to the center of the welding spot (23), and alignment of welding laser and detection laser in the XY direction is realized; s5, operating the welding light source to emit pulse laser for welding, so that a key hole (29) which is stable in size, continuously opened and controllable in depth is formed in the welding spot (23) of the processed workpiece (7), and simultaneously, using the detection vibrating mirror (9) for carrying out multi-point scanning on the welding spot (23); S6, after welding and synchronous scanning are finished, the processing module is used for processing the interference spectrum signals, the optical phase difference of each scanning point (24) is demodulated from the interference spectrum signals, the corresponding height information is calculated, the height information of all the scanning points (24) is combined with the two-dimensional plane position coordinates, and the complete three-dimensional morphology point cloud data of the scanning area (28) can be reconstructed, so that the three-dimensional coordinates of the lowest point of the key hole (29) are obtained; S7, operating the first detection motor (9 a) and the second detection motor (9 d) to adjust the angles of the first detection galvanometer lens (9 b) and the second detection galvanometer lens (9 c), enabling the scanning center of the detection galvanometer (9) to deviate from a preset position to the lowest point of a keyhole (29), and overlapping the detection laser focus (25) and the actual action focus of welding laser in a three-dimensional space, so that the accurate alignment of the two light beams on the action point level is realized; S8, scanning the welding seam of the processed workpiece (7) synchronously with welding by operating the detection vibrating mirror (9), and obtaining the real three-dimensional coordinates of the lowest point of the key hole (29) of the welding seam by using the processing module, so as to obtain the real depth of the lowest point of the key hole (29), namely the welding penetration of the welding seam.
  7. 7. The method of claim 6, wherein in step S3, the scanning is performed by multi-point scanning, and the plurality of scanning points (24) are arranged in a square shape.
  8. 8. The method for detecting laser welding based on keyhole thermal radiation scanning as set forth in claim 6, wherein in step S5, the side length of the scanning area (28) is 2-5 times the diameter of the welding spot (23).
  9. 9. The laser welding detection method based on keyhole thermal radiation scanning as set forth in claim 6, wherein high-purity inert shielding gas is continuously blown to the welding spot area in the welding process of steps S5 to S7.

Description

Laser welding detection device and method based on keyhole thermal radiation scanning Technical Field The invention relates to the technical field of laser welding on-line quality detection, in particular to a laser welding detection device and method based on keyhole thermal radiation scanning. Background With the deep application of the high-power laser welding technology in the field of precision manufacturing, the stability and reliability of welding quality become core factors for limiting process efficiency especially in key scenes such as power batteries of new energy automobiles, consumer electronic structural parts, aerospace thin-wall components and the like. The welding penetration is used as a core index for evaluating the metallurgical bonding quality of a welding seam and predicting the mechanical property of a joint, and the on-line, real-time and accurate measurement is a key premise of the laser welding to intelligent closed-loop control. However, the off-line or indirect detection method commonly adopted in the industry currently has a significant bottleneck in real-time performance and accuracy, and is difficult to meet the increasing demands of modern precision manufacturing on process quality control. In the prior art, the detection of welding penetration mainly comprises two types of destructive detection and online nondestructive detection, and inherent defects exist as follows: 1. destructive detection (such as metallographic analysis) needs to intercept a sample, polish and observe under a microscope, has complicated process, consumes time and has high cost, essentially belongs to post-sampling detection, cannot feed back and intervene in real time in the production process, and has hidden danger of quality risk lag. 2. On-line nondestructive detection can be monitored by a photoelectric sensor (such as plasma luminescence and thermal radiation monitoring). The welding state is inferred indirectly by monitoring the associated physical phenomena during the welding process. The method has high response speed, but the obtained signals and key geometric parameters such as molten pool morphology, penetration and the like have complex correlation models, are easily interfered by process fluctuation, and are difficult to realize direct and quantitative measurement of the penetration. 3. In the online nondestructive detection, active vision/structured light detection (such as laser triangulation) can be adopted, and the method is easily interfered seriously by intense arc light, splash, plasma and smoke dust generated in the welding process, and has low signal to noise ratio. More importantly, the special keyhole structure of laser welding is in a long and narrow tubular shape with a very large depth-to-width ratio (the aperture is usually tens of micrometers), and detection laser beams are difficult to effectively enter the bottom of the keyhole and return signals with sufficient intensity, so that detection of the shape of the bottom is invalid, and the penetration information cannot be accurately obtained. Disclosure of Invention The invention aims to provide a laser welding detection device and method based on keyhole thermal radiation scanning, so that the welding penetration of a welding line can be directly, rapidly and accurately detected under the condition of not damaging a processed workpiece. The technical scheme includes that the laser welding detection device based on keyhole thermal radiation scanning comprises a welding mechanism, a detection mechanism, a data acquisition module, a processing module and a display module, wherein the welding mechanism comprises a welding light source, a welding optical fiber, a welding collimating lens group, a laser beam combining lens, a laser welding vibrating lens and a field lens, and welding laser emitted by the welding light source sequentially passes through the welding optical fiber, the welding collimating lens group, the laser beam combining lens, the laser welding vibrating lens and the field lens and then reaches a processing point on a processing workpiece; The detection mechanism comprises a detection light source, a transmission optical fiber, a polarization isolator, a beam splitting optical fiber coupler, a detection assembly, a reference assembly and a processing assembly, wherein the detection assembly comprises a detection optical fiber, a detection collimating lens group, a detection vibrating mirror and a detection reflecting mirror, laser emitted by the detection light source passes through the transmission optical fiber and the polarization isolator and then reaches the beam splitting optical fiber coupler to be divided into detection laser and reference laser, the detection laser sequentially passes through the detection optical fiber, the detection collimating lens group, the detection vibrating mirror and the detection reflecting mirror and then is reflected to a laser beam combining mirror, the detection laser and