A dual-beam coaxial coupling alignment device and method

Abstract

This invention discloses a dual-beam coaxial coupling alignment device, relating to the field of laser welding monitoring technology. It includes an OCT sensing module, a laser welding head module, and a beam coaxial coupling alignment module. The laser welding head module and the OCT sensing module are connected by a detachable rigid fixed connection. This invention also discloses a dual-beam coaxial coupling alignment method, including: S100, laser welding beam positioning; S200, coarse alignment of the dual beams; and S300, precise alignment of the beam spots at the focal points of the dual beams. This invention achieves precise alignment of the beam spots at the focal points of the dual beams. The alignment process is simple, the alignment efficiency is high, and the accuracy and stability of laser welding penetration monitoring are improved.

Description

Technical Field

[0001] This invention relates to the field of laser welding monitoring technology, and in particular to a dual-beam coaxial coupling alignment device and method. Background Technology

[0002] Laser welding technology is widely used in modern manufacturing, and its high precision and efficiency make it an important tool for precision machining. However, real-time monitoring of the penetration depth (i.e., the depth of the weld) during laser welding has always been a technical challenge. Insufficient or excessive penetration depth directly affects weld strength and airtightness.

[0003] Traditional methods for monitoring weld penetration depth have the following limitations: indirect measurement methods (such as acoustic emission and infrared thermography) rely on modeling the correlation between physical signals and weld penetration depth, are easily affected by environmental noise, and have low accuracy; visual monitoring methods (such as high-speed cameras) cannot penetrate the plasma cloud of the molten pool and can only acquire surface morphology; offline detection methods (such as metallographic sectioning) are destructive and have significant time lag, making closed-loop control impossible. Overall, these methods suffer from insufficient accuracy and slow response speed, making it difficult to meet the demands of high-precision welding.

[0004] In recent years, Optical Coherence Tomography (OCT) technology has been introduced into the field of laser welding weld depth monitoring due to its advantages of high resolution and non-contact measurement. Existing OCT weld depth monitoring methods typically employ a coaxial design with the welding beam, using a dichroic mirror tilted at 45° to transmit one beam of light and reflect another orthogonally, achieving coupling alignment, as seen in invention patents such as "A Laser Welding Head Equipped with Industrial OCT" (Publication No. CN114043088A) and "A Laser Welding Seam Depth Measurement System" (Publication No. CN118189847A). However, due to factors such as installation and fixing angle errors of the dichroic mirror and laser connector, machining and assembly errors in CNC machining, and beam deflection caused by refraction when the beam passes through the tilted mirror (Snell's Law), the sensing beam and welding beam cannot be perfectly coaxially aligned after system assembly, leading to measurement errors or even measurement failures. In addition, there is a visual adjustment method that uses visual guidance to adjust the pitch angle of the OCT to align the focused spots of the two beams on the laser focal plane. This method only achieves alignment at the focal point, but does not solve the problem of coaxial coupling alignment of the two beams, which limits the monitoring of the weld penetration depth and cannot meet the requirements for sensing deep penetration. Furthermore, beam alignment relies on complex manual adjustments, requiring repeated iterations of optical path calibration, which is time-consuming and dependent on the operator's experience.

[0005] Therefore, those skilled in the art are dedicated to developing a dual-beam coaxial coupling alignment device and method. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to solve the problem of the precise coaxial alignment of the OCT sensing beam and the laser welding beam in the prior art, which relies on manual adjustment, resulting in low efficiency and difficulty in ensuring accuracy.

[0007] Existing technologies lack a high-precision, high-efficiency method for coaxial coupling and alignment of two beams (i.e., the OCT sensing beam and the laser welding beam), resulting in insufficient reliability of weld depth monitoring data and hindering the intelligent development of laser welding. The applicant first positions the laser welding beam and locks its transmission path; then, coarsely aligns the two beams coaxially, coarsely adjusting the sensing beam's transmission path to achieve near-coaxial alignment with the welding beam's transmission path; finally, precisely aligns the beam spots at the focal points of the two beams, further refining the sensing beam's transmission path to achieve precise alignment of the two beams at the center of the spot at the focal point.

[0008] In one embodiment of the present invention, a dual-beam coaxial coupling alignment device is provided, comprising:

[0009] The OCT sensing module adjusts the OCT sensing beam transmission path to align with the laser welding beam, sensing the coaxial welding penetration depth, including:

[0010] OCT sensing beam collimator receives the OCT sensing beam and adjusts the OCT sensing beam to collimate the OCT sensing beam.

[0011] The four-dimensional adjustment bracket adjusts the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam;

[0012] The OCT scanning galvanometer is driven by a motor to swing the lens and adjust the transmission direction of the collimated OCT sensing beam.

[0013] The OCT sensing beam collimator is fixed to the four-dimensional adjustment bracket via a semi-fixed connection. The four-dimensional adjustment bracket and the OCT scanning galvanometer are connected via a detachable rigid fixed connection.

[0014] The laser welding head module focuses a coaxial laser welding beam or a visually guided beam onto the workpiece welding area, including:

[0015] The welding laser head receives and outputs a coaxial laser welding beam or a visual guide beam;

[0016] The welding beam lens adjusts the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam;

[0017] A dichroic mirror is installed and fixed at an angle of approximately 45°. It reflects the collimated laser welding beam or the collimated visual guide beam through a surface coating and transmits the collimated OCT sensing beam, thus integrating the collimated OCT sensing beam with the collimated laser welding beam or the collimated visual guide beam.

[0018] A focusing lens is used to focus the integrated collimated OCT sensing beam and the collimated laser welding beam or the collimated visual guide beam together. The focal position of the collimated OCT sensing beam is approximately the focal position of the collimated laser welding beam or the collimated visual guide beam.

[0019] Protect the lens from welding spatter and metal vapors and gases generated during high-temperature welding that could contaminate the optical path.

[0020] Laser welding head module housing, which fixes the welding laser head, welding beam lens, dichroic mirror, focusing lens and protective lens;

[0021] The welding laser head receives and outputs a coaxial laser welding beam or a visual guide beam. The welding beam lens adjusts the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam, which is reflected by a dichroic mirror, then focused by a focusing lens, and finally passes through a protective lens. The welding laser head, welding beam lens, dichroic mirror, focusing lens, and protective lens are fixed to the laser welding head module housing in sequence according to the beam transmission order.

[0022] The beam coaxial coupling alignment module performs coarse alignment of the laser welding beam or the collimated visual guide beam and dual beams coaxially, including:

[0023] One light-transmitting element is used to position and control the transmission of a collimated laser welding beam, a collimated visual guide beam, or a dual beam.

[0024] The coaxial support frame fixes and supports the light-transmitting hole element through a detachable rigid fixed connection. The coaxial support frame through holes are evenly arranged around the perimeter, and radial screw holes of the coaxial support frame through holes are arranged along the radial direction of the coaxial support frame through holes.

[0025] The second light-transmitting element is used to position and control the transmission of the collimated laser welding beam, collimated visual guide beam, or dual beams.

[0026] A two-dimensional photosensitive element receives a collimated laser welding beam or a collimated visual guide beam and dual beams, and forms a visual light spot;

[0027] The two-dimensional adjustment bracket uses a semi-fixed connection method to fix and support the light-transmitting hole element two and the two-dimensional photosensitive element. Adjustment elements are set to adjust the X-axis and Y-axis displacement of the light-transmitting hole element two and the two-dimensional photosensitive element respectively. Two-dimensional adjustment bracket through holes are evenly arranged around the perimeter, and radial screw holes of two-dimensional adjustment bracket through holes are set along the radial direction of the two-dimensional adjustment bracket through holes.

[0028] A smooth support base supports the coaxial structure and is used for fixed placement. The support base has through holes evenly distributed around its perimeter, and radial screw holes are provided along the radial direction of the support base through holes.

[0029] There are multiple coaxial support rods that pass through the through holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base. Bolts are screwed into the radial screw holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base respectively, and the coaxial support rods are tightened to fix them, thereby supporting and fixing the beam coaxial coupling alignment module.

[0030] The light beam is transmitted to the two-dimensional photosensitive element through light-transmitting aperture element one and light-transmitting aperture element two, forming a visible light spot; the laser welding head module and the OCT sensing module are connected by a detachable rigid fixed connection method.

[0031] Optionally, in the dual-beam coaxial coupling alignment device in the above embodiments, the light-transmitting aperture element can be replaced with a variable aperture, a slit, or an alignment aperture element.

[0032] Furthermore, in the dual-beam coaxial coupling alignment device in the above embodiments, the second light-transmitting aperture element is a small circular aperture with a diameter of less than 1 mm.

[0033] Furthermore, in the dual-beam coaxial coupling alignment device in the above embodiments, the diameter of the circular aperture of the second light-transmitting aperture element is smaller than that of the first light-transmitting aperture element.

[0034] Optionally, in the dual-beam coaxial coupling alignment device of any of the above embodiments, the two-dimensional photosensitive element is a CCD or CMOS two-dimensional photosensitive device.

[0035] Optionally, in the dual-beam coaxial coupling alignment device of any of the above embodiments, the OCT scanning galvanometer includes an X-axis reflecting mirror and a Y-axis reflecting mirror. The X-axis reflecting mirror and the Y-axis reflecting mirror are respectively fixed on their respective rotating shafts. The motor drives the rotating shaft to swing the X-axis reflecting mirror to adjust the transmission direction of the collimated OCT sensing beam on the X-axis. The motor drives the rotating shaft to swing the Y-axis reflecting mirror to adjust the transmission direction of the collimated OCT sensing beam on the Y-axis.

[0036] Optionally, in the dual-beam coaxial coupling alignment device of any of the above embodiments, the detachable rigid fixing connection method includes bolt connection.

[0037] Optionally, in the dual-beam coaxial coupling alignment device of any of the above embodiments, the semi-fixed connection method includes a pin connection.

[0038] Furthermore, in the dual-beam coaxial coupling alignment device in the above embodiments, the number of coaxial support rods is the same as the number of through holes in the coaxial support frame, the two-dimensional adjustment bracket, and the support base.

[0039] Preferably, in the dual-beam coaxial coupling alignment device of the above embodiments, the number of coaxial support rods is four.

[0040] Based on any of the above embodiments, another embodiment of the present invention provides a dual-beam coaxial coupling alignment method, comprising the following steps:

[0041] S100, laser welding beam positioning, using coaxial visual guide light to position the laser welding beam, adjusting the laser welding head module and the beam coaxial coupling alignment module to focus the coaxial visual guide light onto the two-dimensional photosensitive element;

[0042] S200, dual-beam coaxial coarse alignment, receiving the OCT sensing beam, adjusting it to collimate the OCT sensing beam, adjusting the transmission direction of the collimated OCT sensing beam, so that the collimated OCT sensing beam is focused on the two-dimensional photosensitive element.

[0043] S300, precise alignment of the dual-beam focal spot: Replace the beam coaxial coupling alignment module with the planar welding workpiece, adjust the laser welding head module so that the dual-beam focal point is placed on the surface of the planar welding workpiece, turn on the laser welding beam, perform in-situ static welding to form a welding spot, use an OCT scanning galvanometer to perform 2D scanning, simultaneously acquire OCT 3D data, process and display in en face mode, fine-tune the OCT scanning galvanometer to move the center of the welding spot in the en face field of view to the center of the en face field of view, and complete the precise alignment of the dual-beam focal spot.

[0044] Optionally, in the dual-beam coaxial coupling alignment method of the above embodiments, step S100 includes:

[0045] S110, Receives and outputs a coaxial visual guide beam; the welding laser head receives and outputs a coaxial visual guide beam.

[0046] S120, Collimated visual guide beam: The welding beam lens adjusts the coaxial visual guide beam into a collimated visual guide beam.

[0047] S130, reflecting collimated and guiding beams, the dichroic mirror reflects collimated and guiding beams through surface coating;

[0048] S140. Adjust the collimated visual guide beam, adjust the placement of the beam coaxial coupling alignment module or adjust the position of the laser welding head module so that the center of the collimated visual guide beam illuminates the center of the light-transmitting hole element one.

[0049] S140. Form a visual light spot. Adjust the two-dimensional adjustment bracket so that the collimated visual guide beam illuminates the center position of the aperture element two, and finally illuminates the two-dimensional photosensitive element to form a visual light spot.

[0050] S150, Laser welding beam positioning: Adjust the positions of the light-transmitting aperture element and the two-dimensional photosensitive element to find the boundary position of the visualized light spot from nothing to something and back to nothing, thereby determining the corresponding intermediate position and obtaining the Gaussian light spot. Lock the transmission path of the laser welding beam and maintain the state of the beam coaxial coupling alignment module. The laser welding beam positioning is completed. If the Gaussian light spot cannot be obtained, proceed to step S160.

[0051] S160. Reduce the light intensity by adding an optical attenuator to the beam coaxial coupling alignment module to reduce the light intensity, and return to step S150.

[0052] Furthermore, in the dual-beam coaxial coupling alignment method of the above embodiments, step S200 includes:

[0053] S210, collimating the OCT sensing beam, the welding laser head stops receiving the coaxial visual guide beam, the OCT sensing beam collimator receives the OCT sensing beam, and adjusts the OCT sensing beam to collimate the OCT sensing beam.

[0054] S220. Adjust the OCT scanning galvanometer, start the OCT scanning galvanometer, and set the X-axis and Y-axis reflecting mirrors of the galvanometer to be kept at the center of the swing range.

[0055] S230. Adjust the displacement and angle of the collimated OCT sensing beam. Use a four-dimensional adjustment bracket to adjust the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam.

[0056] S240, coaxial coarse alignment of dual beams, repeat step S230 until the collimated OCT sensing beam is focused onto the two-dimensional photosensitive element to obtain the Gaussian spot of the collimated OCT sensing beam. When the center position of the Gaussian spot of the collimated OCT sensing beam coincides with the center position of the Gaussian spot positioned by the laser welding beam and the spot shape is consistent, lock the state of the four-dimensional adjustment bracket.

[0057] Furthermore, in the dual-beam coaxial coupling alignment method of the above embodiments, step S300 includes:

[0058] S310. Replace the beam coaxial coupling alignment module with a planar welding workpiece. Adjust the laser welding head module through OCT imaging feedback so that the focus of the dual beams is placed on the surface of the planar welding workpiece.

[0059] S320, In-situ static welding spot: Turn on the laser welding beam and perform in-situ static welding spot to form a welding spot. Under the premise of ensuring the welding spot is visible, the smaller the size of the welding spot, the better.

[0060] S330: Acquires OCT 3D data, performs 2D scanning using an OCT scanning galvanometer, simultaneously acquires OCT 3D data, processes the acquired OCT data signals, and displays them in en face mode;

[0061] S340. Complete the precise alignment of the spot at the focal position of the dual beams. Fine-tune the OCT scanning galvanometer to move the center of the welding spot in the en face field of view to the center of the en face field of view. Record the swing position of the X-axis reflecting mirror and the Y-axis reflecting mirror in the OCT scanning galvanometer corresponding to the center position of the en face field of view. Complete the precise alignment of the spot at the focal position of the dual beams.

[0062] Furthermore, in the dual-beam coaxial coupling alignment method in the above embodiments, during the actual welding operation, the OCT scanning galvanometer is activated, and the swing positions of the X-axis reflecting mirror and the Y-axis reflecting mirror are set to the swing positions recorded in step S340.

[0063] Furthermore, in the dual-beam coaxial coupling alignment method in the above embodiments, the processing of the OCT acquired data signal includes K-linearization correction, dispersion correction, removal of DC term, windowing to suppress sidelobes, Fourier transform, and logarithmic transform.

[0064] This invention achieves coaxial coupling alignment of two laser beams through alignment of a laser welding head module, a beam coaxial coupling alignment module, and an OCT sensing module. It uses a visual guide light to lock the transmission path of the welding beam for laser beam positioning, adjusts the OCT beam transmission path to achieve near coaxial alignment with the welding beam, performs coarse alignment of the two beams, and uses OCT imaging feedback for fine-tuning to ensure precise overlap of the beam centers at the focal points. This results in precise alignment of the beam centers at the focal points of the two beams. The alignment process is simple, efficient, and improves the accuracy and stability of laser welding penetration monitoring.

[0065] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0066] Figure 1This is a schematic diagram of the structure of a dual-beam coaxial coupling alignment device according to an exemplary embodiment;

[0067] Figure 2 This is a flowchart of a dual-beam coaxial coupling alignment method according to an exemplary embodiment;

[0068] Figure 3 This is a welding penetration sensing effect diagram of the existing OCT penetration monitoring method;

[0069] Figure 4 This is an en-face view of the exemplary embodiment of the dual-beam coaxial coupling alignment device and method, showing the alignment of the center point of the en-face view with the center of the welding spot.

[0070] Figure 5 This is an illustration of the welding penetration sensing effect of the dual-beam coaxial coupling alignment device and method in an exemplary embodiment.

[0071] In the picture:

[0072] 1. OCT sensing beam collimator; 2. Four-dimensional adjustment bracket; 3. Galvanometer X-axis reflecting mirror; 4. Galvanometer Y-axis reflecting mirror; 5. OCT scanning galvanometer; 6. Dichroic mirror; 7. Welding beam lens; 8. Welding laser head; 9. Focusing lens; 10. Protective lens; 11. Laser welding head module; 12. Light-transmitting aperture element one; 13. Coaxial support frame; 14. Two-dimensional adjustment bracket; 15. Light-transmitting aperture element two; 16. Two-dimensional photosensitive element; 17. Coaxial support rod; 18. Smooth support base; 19. Beam coaxial coupling alignment module; 20. OCT sensing module. Detailed Implementation

[0073] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0074] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of components is schematically exaggerated in some places in the drawings.

[0075] The applicant designed a dual-beam coaxial coupling alignment device, such as Figure 1 As shown, it includes:

[0076] The OCT sensing module adjusts the OCT sensing beam transmission path to align with the laser welding beam, sensing the coaxial welding penetration depth, including:

[0077] OCT sensing beam collimator receives the OCT sensing beam and adjusts the OCT sensing beam to collimate the OCT sensing beam.

[0078] The four-dimensional adjustment bracket adjusts the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam;

[0079] The OCT scanning galvanometer includes an X-axis reflecting mirror and a Y-axis reflecting mirror. The X-axis reflecting mirror and the Y-axis reflecting mirror are fixed on their respective rotating shafts. The motor drives the rotating shaft to swing the X-axis reflecting mirror to adjust the transmission direction of the collimated OCT sensing beam on the X-axis. The motor drives the rotating shaft to swing the Y-axis reflecting mirror to adjust the transmission direction of the collimated OCT sensing beam on the Y-axis.

[0080] The OCT sensing beam collimator is fixed to the four-dimensional adjustment bracket via a semi-fixed connection, and the four-dimensional adjustment bracket and the OCT scanning galvanometer are connected by bolts.

[0081] The laser welding head module focuses a coaxial laser welding beam or a visually guided beam onto the workpiece welding area, including:

[0082] The welding laser head receives and outputs a coaxial laser welding beam or a visual guide beam;

[0083] The welding beam lens adjusts the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam;

[0084] A dichroic mirror is installed and fixed at an angle of approximately 45°. It reflects the collimated laser welding beam or the collimated visual guide beam through a surface coating and transmits the collimated OCT sensing beam, thus integrating the collimated OCT sensing beam with the collimated laser welding beam or the collimated visual guide beam.

[0085] A focusing lens is used to focus the integrated collimated OCT sensing beam and the collimated laser welding beam or the collimated visual guide beam together. The focal position of the collimated OCT sensing beam is approximately the focal position of the collimated laser welding beam or the collimated visual guide beam.

[0086] Protect the lens from welding spatter and metal vapors and gases generated during high-temperature welding that could contaminate the optical path.

[0087] Laser welding head module housing, which fixes the welding laser head, welding beam lens, dichroic mirror, focusing lens and protective lens;

[0088] The welding laser head receives and outputs a coaxial laser welding beam or a visual guide beam. The welding beam lens adjusts the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam, which is reflected by a dichroic mirror, then focused by a focusing lens, and finally passes through a protective lens. The welding laser head, welding beam lens, dichroic mirror, focusing lens, and protective lens are fixed to the laser welding head module housing in sequence according to the beam transmission order.

[0089] The beam coaxial coupling alignment module performs coarse alignment of the laser welding beam or the collimated visual guide beam and dual beams coaxially, including:

[0090] The first light-transmitting element is used to position and control the laser welding beam, collimated visual guide beam, or dual beam. The first light-transmitting element can be a variable aperture, slit, or alignment aperture element.

[0091] A coaxial support frame is used to fix and support the light-transmitting hole element by bolt connection. Coaxial support frame through holes are evenly arranged around the perimeter, and radial screw holes of the coaxial support frame through holes are arranged along the radial direction of the coaxial support frame through holes.

[0092] The second light-transmitting element is a circular hole with a diameter of less than 1 mm. The diameter of the circular hole is smaller than that of the first light-transmitting element. It is used to position and control the laser welding beam or the collimated visual guide beam and dual beam.

[0093] Two-dimensional photosensitive elements, which are CCD or CMOS two-dimensional photosensitive devices, receive collimated laser welding beams or collimated visual guide beams and dual beams, and form a visual light spot;

[0094] The two-dimensional adjustment bracket uses a semi-fixed connection method to fix and support the light-transmitting hole element two and the two-dimensional photosensitive element. The semi-fixed connection method includes pin connection, and adjustment elements are set to adjust the X-axis and Y-axis displacement of the light-transmitting hole element two and the two-dimensional photosensitive element respectively. Two-dimensional adjustment bracket through holes are evenly arranged around the periphery, and radial screw holes of two-dimensional adjustment bracket through holes are set along the radial direction of the two-dimensional adjustment bracket through holes.

[0095] A smooth support base supports the coaxial structure and is used for fixed placement. The support base has through holes evenly distributed around its perimeter, and radial screw holes are provided along the radial direction of the support base through holes.

[0096] There are four coaxial support rods, the same number as the through holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base. They pass through the through holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base, and are fixed by screwing bolts into the radial screw holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base, respectively. The coaxial support rods are then tightened to support and fix the beam coaxial coupling alignment module.

[0097] The light beam is transmitted to the two-dimensional photosensitive element through the first and second light-transmitting elements to form a visible light spot; the laser welding head module and the OCT sensing module are connected by bolts.

[0098] Based on the above embodiments, the applicant provides a dual-beam coaxial coupling alignment method, such as... Figure 2 As shown, it includes the following steps:

[0099] S100, Laser welding beam positioning: The laser welding beam is positioned using a coaxial visible guide light. The laser welding head module and the coaxial coupling alignment module are adjusted to focus the coaxial visible guide light onto the two-dimensional photosensitive element; specifically including:

[0100] S110, Receives and outputs a coaxial visual guide beam; the welding laser head receives and outputs a coaxial visual guide beam.

[0101] S120, Collimated visual guide beam: The welding beam lens adjusts the coaxial visual guide beam into a collimated visual guide beam.

[0102] S130, reflecting collimated and guiding beams, the dichroic mirror reflects collimated and guiding beams through surface coating;

[0103] S140. Adjust the collimated visual guide beam, adjust the placement of the beam coaxial coupling alignment module or adjust the position of the laser welding head module so that the center of the collimated visual guide beam illuminates the center of the light-transmitting hole element one.

[0104] S140. Form a visual light spot. Adjust the two-dimensional adjustment bracket so that the collimated visual guide beam illuminates the center position of the aperture element two, and finally illuminates the two-dimensional photosensitive element to form a visual light spot.

[0105] S150, Laser welding beam positioning: Adjust the positions of the light-transmitting aperture element and the two-dimensional photosensitive element to find the boundary position of the visualized light spot from nothing to something and back to nothing, thereby determining the corresponding intermediate position and obtaining the Gaussian light spot. Lock the transmission path of the laser welding beam and maintain the state of the beam coaxial coupling alignment module. The laser welding beam positioning is completed. If the Gaussian light spot cannot be obtained, proceed to step S160.

[0106] S160. Reduce the light intensity by adding an optical attenuator to the beam coaxial coupling alignment module to reduce the light intensity, and return to step S150.

[0107] S200, dual-beam coaxial coarse alignment, receiving the OCT sensing beam, adjusting it to collimate the OCT sensing beam, adjusting the transmission direction of the collimated OCT sensing beam, so that the collimated OCT sensing beam is focused on the two-dimensional photosensitive element; specifically including:

[0108] S210, collimating the OCT sensing beam, the welding laser head stops receiving the coaxial visual guide beam, the OCT sensing beam collimator receives the OCT sensing beam, and adjusts the OCT sensing beam to collimate the OCT sensing beam.

[0109] S220. Adjust the OCT scanning galvanometer, start the OCT scanning galvanometer, and set the X-axis and Y-axis reflecting mirrors of the galvanometer to be kept at the center of the swing range.

[0110] S230. Adjust the displacement and angle of the collimated OCT sensing beam. Use a four-dimensional adjustment bracket to adjust the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam.

[0111] S240, coaxial coarse alignment of dual beams, repeat step S230 until the collimated OCT sensing beam is focused onto the two-dimensional photosensitive element to obtain the Gaussian spot of the collimated OCT sensing beam. When the center position of the Gaussian spot of the collimated OCT sensing beam coincides with the center position of the Gaussian spot positioned by the laser welding beam and the spot shape is consistent, lock the state of the four-dimensional adjustment bracket.

[0112] S300, precise alignment of the dual-beam focal spot: Replace the coaxial coupling alignment module with a planar welding workpiece, adjust the laser welding head module to place the dual-beam focal point on the surface of the planar welding workpiece, turn on the laser welding beam, and perform in-situ static welding to form a welding spot. Use an OCT scanning galvanometer for 2D scanning and simultaneously acquire OCT 3D data. After processing, display it in en-face mode. Fine-tune the OCT scanning galvanometer to move the center of the welding spot in the en-face field of view to the center of the en-face field of view, completing the precise alignment of the dual-beam focal spot; specifically including:

[0113] S310. Replace the beam coaxial coupling alignment module with a planar welding workpiece. Adjust the laser welding head module through OCT imaging feedback so that the focus of the dual beams is placed on the surface of the planar welding workpiece.

[0114] S320, In-situ static welding spot: Turn on the laser welding beam and perform in-situ static welding spot to form a welding spot. Under the premise of ensuring the welding spot is visible, the smaller the size of the welding spot, the better.

[0115] S330: Acquires OCT 3D data, performs 2D scanning using an OCT scanning galvanometer, and simultaneously acquires OCT 3D data. Processes the OCT acquired data signals, including K-linearization correction, dispersion correction, DC term removal, windowing to suppress sidelobes, Fourier transform, logarithmic transform, and displays in en face mode.

[0116] S340. Complete the precise alignment of the spot at the focal position of the dual beams. Fine-tune the OCT scanning galvanometer to move the center of the welding spot in the en face field of view to the center of the en face field of view. Record the swing position of the X-axis reflecting mirror and the Y-axis reflecting mirror in the OCT scanning galvanometer corresponding to the center position of the en face field of view. Complete the precise alignment of the spot at the focal position of the dual beams.

[0117] To verify the technical effects of the above embodiments, the applicant conducted experiments and compared the welding penetration sensing effects using existing OCT penetration depth monitoring methods and the dual-beam coaxial coupling alignment device and method of the above embodiments. The welding power was set to 1000 watts, the welding speed to 5 mm / s, the welding time to 4 seconds, the total welding length to 2 cm, and the workpiece to be welded to low-carbon steel. Based on existing OCT penetration depth monitoring methods, such as... Figure 3 As shown, the red line represents the actual weld penetration depth. Because the OCT spot and the welding spot are only aligned at the focal point without ensuring that the two beams are completely coaxial, the two beams are not precisely aligned. When the welding depth is too deep, the OCT beam cannot reach the bottom of the keyhole generated by the high-temperature operation of the welding beam. Therefore, the weld penetration depth monitored by OCT is shallower than the actual penetration depth. The deeper the weld penetration depth, the greater the measurement error.

[0118] Based on the dual-beam coaxial coupling alignment device and method described in the above embodiments, precise alignment of the dual beams is achieved. For example... Figure 4 As shown, the two beams are coaxially coupled and precisely coincide with the center of the weld spot at the center point of the en face view. The yellow circle represents the center of the weld spot, and the red line represents the center line of the crosshairs in the en face view.

[0119] The applicant further compared the welding penetration sensing effect after achieving precise coaxial alignment of dual beams using the present invention, such as... Figure 5 As shown, the dual-beam coaxial coupling alignment device and method of the embodiment, after the dual beams are precisely aligned coaxially, the OCT can directly irradiate the bottom of the keyhole to sense the weld penetration depth. The depth sensed by the OCT is approximately consistent with the actual weld penetration depth represented by the red line, and the measurement results are accurate, thus improving the precision of welding processing quality.

[0120] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A dual-beam coaxial coupling alignment device, characterized in that, include: The OCT sensing module adjusts the OCT sensing beam transmission path to align with the laser welding beam, sensing the coaxial welding penetration depth, including: OCT sensing beam collimator receives the OCT sensing beam and adjusts the OCT sensing beam to collimate the OCT sensing beam; The four-dimensional adjustment bracket adjusts the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam; The OCT scanning galvanometer is driven by a motor to swing the lens, thereby adjusting the transmission direction of the collimated OCT sensing beam; The OCT sensing beam collimator is fixed to the four-dimensional adjustment bracket via a semi-fixed connection. The four-dimensional adjustment bracket and the OCT scanning galvanometer are connected via a detachable rigid fixed connection. The laser welding head module focuses a coaxial laser welding beam or a visually guided beam onto the workpiece welding area, including: The welding laser head receives and outputs the coaxial laser welding beam or visual guide beam; A welding beam lens is used to adjust the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam. A dichroic mirror is installed and fixed at an angle of approximately 45°. It reflects the collimated laser welding beam or the collimated visual guide beam through a surface coating and transmits the collimated OCT sensing beam, thus integrating the collimated OCT sensing beam with the collimated laser welding beam or the collimated visual guide beam. A focusing lens is used to focus the integrated collimated OCT sensing beam and the collimated laser welding beam or the collimated visual guide beam together. The focal position of the collimated OCT sensing beam is approximately the focal position of the collimated laser welding beam or the collimated visual guide beam. Protect the lens from welding spatter and metal vapors and gases generated during high-temperature welding that could contaminate the optical path. The laser welding head module housing secures the welding laser head, the welding beam lens, the dichroic mirror, the focusing lens, and the protective lens. The welding laser head receives and outputs the coaxial laser welding beam or visual guide beam. The welding beam lens adjusts the coaxial laser welding beam or visual guide beam into a collimated laser welding beam or collimated visual guide beam, which is reflected by the dichroic mirror, then focused by the focusing lens, and finally passes through the protective lens. The welding laser head, the welding beam lens, the dichroic mirror, the focusing lens, and the protective lens are fixed to the laser welding head module housing in sequence according to the beam transmission order. The beam coaxial coupling alignment module performs coarse alignment of the collimated laser welding beam or collimated visual guide beam and the dual-beam coaxial alignment, including: The first light-transmitting element is used to position and control the transmission of the collimated laser welding beam or the collimated visual guide beam and the dual beams. A coaxial support frame is used to fix and support the light-transmitting hole element through a detachable rigid fixed connection. Coaxial support frame through holes are evenly arranged around the periphery, and radial screw holes of the coaxial support frame through holes are arranged along the radial direction of the coaxial support frame through holes. The second light-transmitting element is used to position and control the transmission of the collimated laser welding beam or the collimated visual guide beam and the dual beams. A two-dimensional photosensitive element receives the collimated laser welding beam or the collimated visual guide beam and the dual beams, and forms a visual light spot; A two-dimensional adjustment bracket is used to fix and support the second light-transmitting hole element and the two-dimensional photosensitive element in a semi-fixed connection manner. An adjustment element is set to adjust the X-axis and Y-axis displacement of the second light-transmitting hole element and the two-dimensional photosensitive element respectively. Two-dimensional adjustment bracket through holes are evenly arranged around the periphery, and radial screw holes of the two-dimensional adjustment bracket through holes are arranged along the radial direction of the two-dimensional adjustment bracket through holes. A smooth support base supports a coaxial structure and is used for fixed placement. The support base has through holes evenly distributed around its perimeter, and radial screw holes are provided along the radial direction of the support base through holes. Multiple coaxial support rods pass through the through holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base. Bolts are screwed into the radial screw holes of the coaxial support frame, the two-dimensional adjustment bracket, and the support base, respectively, and are tightened against the coaxial support rods for fixation, thereby supporting and fixing the beam coaxial coupling alignment module. The laser welding head module and the OCT sensing module are connected by a detachable rigid fixed connection.

2. The dual-beam coaxial coupling alignment device as described in claim 1, characterized in that, The OCT scanning galvanometer includes an X-axis reflecting mirror and a Y-axis reflecting mirror. The X-axis reflecting mirror and the Y-axis reflecting mirror are respectively fixed on their respective rotating shafts. The motor drives the rotating shaft to swing the X-axis reflecting mirror, adjusting the transmission direction of the collimated OCT sensing beam on the X-axis. The motor drives the rotating shaft to swing the Y-axis reflecting mirror, adjusting the transmission direction of the collimated OCT sensing beam on the Y-axis.

3. The dual-beam coaxial coupling alignment device as described in claim 1, characterized in that, The light-transmitting aperture element can be replaced with a variable aperture, a slit, or an alignment aperture element.

4. The dual-beam coaxial coupling alignment device as described in claim 3, characterized in that, The diameter of the circular aperture of the second light-transmitting element is smaller than that of the first light-transmitting element.

5. The dual-beam coaxial coupling alignment device as described in claim 1, characterized in that, The detachable rigid fixed connection method includes bolt connection.

6. The dual-beam coaxial coupling alignment device as described in claim 1, characterized in that, The number of coaxial support rods is the same as the number of through holes in the coaxial support frame, the two-dimensional adjustment bracket, and the support base.

7. A dual-beam coaxial coupling alignment method, using the dual-beam coaxial coupling alignment device as described in any one of claims 1-6, characterized in that, Includes the following steps: S100, Laser welding beam positioning: The laser welding beam is positioned by coaxial visible guide light. The laser welding head module and the coaxial coupling alignment module are adjusted so that the coaxial visible guide light is focused on the two-dimensional photosensitive element. S200, dual-beam coaxial coarse alignment, receiving OCT sensing beam, adjusting to collimate OCT sensing beam, adjusting the transmission direction of the collimated OCT sensing beam, so that the collimated OCT sensing beam is focused on the two-dimensional photosensitive element; S300. The laser beams are precisely aligned at their focal points. The coaxial coupling alignment module is replaced with a planar welding workpiece. The laser welding head module is adjusted so that the focal points of the two beams are placed on the surface of the planar welding workpiece. The laser welding beam is turned on, and in-situ static welding is performed to form a welding spot. The OCT scanning galvanometer is used for 2D scanning, simultaneously acquiring OCT 3D data. After processing, the data is displayed in en-face mode. The OCT scanning galvanometer is finely adjusted to move the center of the welding spot in the en-face field of view to the center of the en-face field of view, thus completing the precise alignment of the focal points of the two beams.

8. The dual-beam coaxial coupling alignment method as described in claim 7, characterized in that, Step S100 includes: S110, Receive and output a coaxial visual guide beam, wherein the welding laser head receives and outputs the coaxial visual guide beam; S120, Collimated visual guide beam, wherein the welding beam lens adjusts the coaxial visual guide beam into the collimated visual guide beam; S130, Reflecting collimated visual guide beam, wherein the dichroic mirror reflects the collimated visual guide beam through a surface coating; S140. Adjust the collimated visual guide beam, adjust the placement position of the beam coaxial coupling alignment module or adjust the position of the laser welding head module so that the center of the collimated visual guide beam irradiates the center position of the light-transmitting hole element one. S140. Form a visual light spot by adjusting the two-dimensional adjustment bracket so that the collimated visual guide beam illuminates the center position of the aperture element two, and finally illuminates the two-dimensional photosensitive element to form a visual light spot. S150, Laser welding beam positioning: Adjust the positions of the light-transmitting aperture element two and the two-dimensional photosensitive element to find the boundary position of the visualized light spot from nothing to something and back to nothing, thereby determining the corresponding intermediate position, obtaining the Gaussian light spot, locking the transmission path of the laser welding beam, maintaining the state of the beam coaxial coupling alignment module, and the laser welding beam positioning ends; when the Gaussian light spot cannot be obtained, execute step S160; S160. Reduce the light intensity by adding an optical attenuator to the coaxial coupling alignment module of the beam to reduce the light intensity, and then return to execute step S150.

9. The dual-beam coaxial coupling alignment method as described in claim 8, characterized in that, Step S200 includes: S210, Collimate the OCT sensing beam, the welding laser head stops receiving the coaxial visual guide beam, the OCT sensing beam collimator receives the OCT sensing beam, and adjusts the OCT sensing beam to collimate the OCT sensing beam; S220. Adjust the OCT scanning mirror, start the OCT scanning mirror, and set the X-axis reflecting mirror and the Y-axis reflecting mirror to be kept at the center position of the swing range; S230. Adjust the displacement and angle of the collimated OCT sensing beam. Using the four-dimensional adjustment bracket, adjust the X-axis and Y-axis displacement direction, pitch angle, and deflection angle of the collimated OCT sensing beam. S240, coaxial coarse alignment of dual beams, repeatedly execute step S230 until the collimated OCT sensing beam is focused on the two-dimensional photosensitive element to obtain the Gaussian spot of the collimated OCT sensing beam. When the center position of the Gaussian spot of the collimated OCT sensing beam coincides with the center position of the Gaussian spot positioned by the laser welding beam and the spot shape is consistent, lock the state of the four-dimensional adjustment bracket.

10. The dual-beam coaxial coupling alignment method as described in claim 9, characterized in that, Step S300 includes: S310. Replace the beam coaxial coupling alignment module with a planar welding workpiece, and adjust the laser welding head module through OCT imaging feedback so that the dual beam focus is placed on the surface of the planar welding workpiece. S320. In-situ static welding spot: Turn on the laser welding beam and perform in-situ static welding spot to form a welding spot. Under the premise of ensuring that the welding spot is visible, the smaller the size of the welding spot, the better. S330. Acquire OCT 3D data, perform 2D scanning using the OCT scanning galvanometer, simultaneously acquire OCT 3D data, process the acquired OCT data signals, and display them in en face mode; S340. Complete the precise alignment of the spot at the focal point of the dual beams. Fine-tune the OCT scanning galvanometer to move the center of the welding spot in the en face field of view to the center of the en face field of view. Record the swing positions of the X-axis reflecting mirror and the Y-axis reflecting mirror in the OCT scanning galvanometer corresponding to the center position of the en face field of view, and complete the precise alignment of the spot at the focal point of the dual beams.

Images