An ultra-thin Invar alloy small-deformation mirror welding device and method based on pulsed laser staggered step distribution

Abstract

The present invention discloses an ultra-thin Invar alloy small-deformation mirror welding device and method based on pulse laser staggered step distribution, including a control system, a multi-source laser system, a pulse-continuous laser composite welding head A, a pulse-continuous laser composite welding head B, a mirror displacement monitoring system and a weldment. The control system is connected to the multi-source laser system and the mirror displacement monitoring system through connecting wires. The present invention can effectively adjust the distribution of the mirror laser energy of the multi-source laser in response to the dynamic changes in the deformation on both sides of the weldment during the laser welding process of the existing thin-walled Invar alloy, solve problems such as excessive deformation and low weld forming uniformity in the laser welding of the Invar alloy thin-walled structure, and has a high degree of automation, real-time monitoring and adjustment, can realize the rapid switching of different distributed laser mirror welding methods, realizes the dynamic conjugate optimization during the welding process, and is of great significance for the high-efficiency and high-quality welding of thin plate welding structures.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser welding, and particularly relates to an ultra-thin Invar alloy small-deformation mirror welding device and method based on a pulse laser staggered step distribution. Background Art

[0002] The Invar alloy with a thickness of only 0.7 mm is adopted in the thin-film LNG fuel tank, and the manufacturing is carried out by welding technology. The laser welding technology is a welding method with high efficiency and high precision. However, for the ultra-thin wall Invar alloy welding structure, problems such as insufficient self-rigidity of the structure and continuous heat accumulation in the welding area are likely to cause the welding deformation to exceed the limit, making it difficult to meet the service requirements. Therefore, the small-deformation laser welding technology applied to the Invar alloy thin-wall structure needs to be further broken through.

[0003] The laser mirror welding technology can realize the conjugate distribution of stress and deformation in the welding process by symmetrically arranging two laser beams on both sides of the weld seam and implementing the welding method. Therefore, the mirror distribution of laser energy can reduce the welding deformation to a certain extent. However, the welding deformation is also affected by factors such as clamping constraints, heat source accumulation, and assembly accuracy, resulting in a real-time change state of the welding deformation during the welding process. Especially for the ultra-thin wall welding structure, multi-directional curved surface deformation occurs under the superposition influence of multiple factors such as continuous heat input accumulation and boundary conditions. In addition, in order to obtain a weld seam that just penetrates and has a stable weld seam size, the ultra-thin wall structure is extremely sensitive to the adjustment of welding parameters such as laser power.

[0004] The pulsed laser can output optical pulses with a high energy density in a short time, which can provide a higher welding speed and more precise energy control, and is suitable for fields with high requirements for welding quality and efficiency. How to give full play to the advantages of the pulsed laser, design an energy spatio-temporal distribution scheme that meets the welding deformation and joint forming quality requirements of the Invar alloy thin-wall structure, and achieve small-deformation and high-quality welding of the ultra-thin Invar alloy is still a problem that needs to be solved by the laser welding technology.

[0005] Therefore, we propose an ultra-thin Invar alloy small-deformation mirror welding device and method based on a pulse laser staggered step distribution to solve the above problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an ultra-thin Invar alloy small-deformation mirror welding device and method based on a pulse laser staggered step distribution.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] An ultra-thin Invar alloy small-deformation mirror welding device based on pulse laser staggered step distribution, comprising a control system, a multi-source laser system, a pulse-continuous laser composite welding head A, a pulse-continuous laser composite welding head B, a mirror displacement monitoring system and a welding part. The control system is respectively connected to the multi-source laser system and the mirror displacement monitoring system through connecting wires.

[0009] Preferably, the multi-source laser system is used to output a continuous-pulse composite laser beam, and includes a semiconductor laser A, a pulsed fiber laser A, a semiconductor laser B, and a pulsed fiber laser B. Among them, the semiconductor laser A and the pulsed fiber laser A are connected to the pulse-continuous laser composite welding head through a transmission fiber, and the semiconductor laser B and the pulsed fiber laser B are connected to the pulse-continuous laser composite welding head B through a transmission fiber.

[0010] Preferably, the pulse-continuous laser composite welding head A includes a semiconductor laser beam A, a pulsed fiber laser beam A, a pulsed fiber laser transmission end, a fiber laser collimating lens, a movable reflection device, a semiconductor laser transmission end, a semiconductor laser collimating lens, a beam splitter, and a confocal lens.

[0011] Preferably, the internal structure of the pulse-continuous laser composite welding head B is the same as that of the pulse-continuous laser composite welding head A.

[0012] Preferably, the mirror displacement monitoring system is used to monitor the angular deformation of the welding part during the welding process in real time, and includes a displacement sensing device A1, a displacement sensing device A2, a displacement sensing device B1, and a displacement sensing device B2. The displacement sensing device A1 and the displacement sensing device A2 are installed on the pulse-continuous laser relatively position-adjustable welding head A.

[0013] Preferably, the pulse-continuous laser composite welding head A and the pulse-continuous laser composite welding head B are symmetrically arranged on both sides of the welding part and are independent of each other, and their spatial postures are respectively controlled by the control system.

[0014] Preferably, the movable reflection device includes a slide rail, a liftable lens mounting groove, and a reflection lens. The liftable lens mounting groove adjusts the height position of the reflection lens through the slide rail to control the relative position of the pulsed fiber laser spot and the semiconductor laser spot.

[0015] Preferably, the semiconductor laser A and the pulsed fiber laser A respectively transmit the laser beams to the semiconductor laser transmission end and the pulsed fiber laser transmission end through their respective transmission fibers; the semiconductor laser beam is connected to the pulsed-continuous laser composite welding head through the semiconductor laser transmission end, and then successively passes through the semiconductor laser collimating lens, the beam splitting lens, and the confocal lens to reach the workpiece surface; the pulsed fiber laser beam is connected to the pulsed-continuous laser composite welding head through the pulsed fiber laser transmission end, and then successively passes through the fiber laser collimating lens, the movable reflection device, the beam splitting lens, and the confocal lens to reach the workpiece surface.

[0016] Preferably, the reflectivity of the beam splitting lens to the pulsed fiber laser beam with a wavelength of 1064 nm is 99.99%, and the transmittance to the semiconductor laser beam with a wavelength of 915 nm is 99.99%.

[0017] Preferably, during the welding process, the mirror displacement monitoring system monitors and measures the deformation amount d on the A side in real time A and the deformation amount d on the B side B , and feeds back the deformation amounts on both sides to the control system. The control system solves the difference between the deformation amounts on both sides, and determines parameters such as the pulsed fiber laser power, pulse frequency, pulse laser duration, and relative position of the bilateral pulsed fiber laser beams on both sides according to the difference solution amount.

[0018] Preferably, when the absolute value of the difference between the deformation amounts on both sides |d A - d B | < a, symmetric distributed laser mirror welding is adopted; when a < |d A - d B | < b, staggered distributed laser mirror welding is adopted; when b < |d A - d B | < c, unilateral step distributed laser mirror welding is adopted; when c < |d A - d B | < d, bilateral asymmetric step distributed laser mirror welding is adopted, where a < b < c < d.

[0019] Preferably, the control system adjusts parameters such as the pulse fiber laser power, pulse frequency, and pulse laser duration by controlling the multi-source laser system, and adjusts the relative position of the bilateral pulse fiber laser beams by controlling the movable reflection device; in the case of a small deformation amount, the control system adopts a symmetric distributed laser mirror welding method by controlling the multi-source laser system; in the case of a large deformation amount, the control system, according to the ratio of the deformation amount to the thickness of the welded part, controls the multi-source laser system and the movable reflection device to perform staggered distributed, unilateral step distributed, and bilateral asymmetric step distributed laser mirror welding methods, and achieves the purpose of correcting the deformation on both sides of the welded part by controlling the asymmetric distribution of the bilateral energy; after the deformation amount is reduced, the control system restores the bilateral energy distribution mode to a symmetric distribution to achieve precise control of the bilateral deformation amount.

[0020] The present invention also provides a method for mirror welding of ultra-thin Invar alloy with small deformation based on the staggered step distribution of pulsed laser, using an ultra-thin Invar alloy small deformation mirror welding device based on the staggered step distribution of pulsed laser. The welding method includes the following steps:

[0021] Step 1: Install and fix the ultra-thin Invar alloy welded part;

[0022] Step 2: Turn on the mirror displacement monitoring system and ensure the pre-welding deformation through the mirror displacement monitoring system;

[0023] Step 3: Adjust the positions of the pulsed-continuous laser composite welding head A and the pulsed-continuous laser composite welding head B according to the weld position so that they present a mirror distribution relative to the weld;

[0024] Step 4: Input the thickness of the welded part into the control system;

[0025] Step 5: According to the welding requirements, set the bilateral pulse fiber laser power, pulse frequency, pulse laser duration, semiconductor laser power, and welding speed through the control panel in the control system;

[0026] Step 6: The control system turns on the semiconductor laser A, pulsed fiber laser A, semiconductor laser B, and pulsed fiber laser B to start the laser mirror welding operation;

[0027] Step 7: During the welding process, the mirror displacement monitoring system records the deformation of the welded part in real time and feeds it back to the control system. The control system calculates the difference between the deformation amounts on both sides and dynamically adjusts the parameters according to the calculated difference, including: the pulse fiber laser power on both sides, the pulse frequency, the pulse laser duration, and the relative position of the bilateral pulse fiber laser beams, so as to achieve rapid switching between the symmetric distributed laser mirror welding method, the staggered distributed laser mirror welding method, the unilateral step distributed laser mirror welding method, and the bilateral asymmetric step distributed laser mirror welding method, ensuring that the deformation amount is controlled within the threshold range and completing the welding.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The present invention can effectively adjust the distribution of multi-source laser mirror laser energy in response to the dynamic changes in the deformation of both sides of the welded part during the laser welding process of the existing thin-walled Invar alloy, solve problems such as excessive deformation and low weld forming uniformity in the laser welding of Invar alloy thin-walled structures, and has a high degree of automation, real-time monitoring and adjustment, can achieve rapid switching between different distributed laser mirror welding methods, realizes dynamic conjugate optimization during the welding process, and is of great significance for the high-efficiency and high-quality welding of thin plate welding structures. Description of the Drawings

[0030] Figure 1 is a schematic diagram of an ultra-thin Invar alloy small-deformation mirror welding device based on pulse laser staggered step distribution;

[0031] Figure 2 is a schematic diagram of a welding head with adjustable relative position of pulse-continuous laser in an ultra-thin Invar alloy small-deformation mirror welding device based on pulse laser staggered step distribution;

[0032] Figure 3 is a schematic diagram of the relative position of pulse-continuous laser composite laser in an ultra-thin Invar alloy small-deformation mirror welding device based on pulse laser staggered step distribution;

[0033] Figure 4 is a schematic diagram of the rapid switching of the bilateral pulse laser staggered step distribution strategy in an ultra-thin Invar alloy small-deformation mirror welding device based on pulse laser staggered step distribution.

[0034] In the figure: 1, control system; 2, multi-source laser system; 3, pulse-continuous laser composite welding head A; 4, pulse-continuous laser composite welding head B; 5 - mirror displacement monitoring system; 6 - welded part;

[0035] 21, semiconductor laser A; 22, pulse fiber laser A; 23, semiconductor laser B; 24, pulse fiber laser B;

[0036] 31. Semiconductor laser beam A; 311. Semiconductor laser spot; 32. Pulsed fiber laser beam A; 321. Pulsed fiber laser spot; 33. Pulsed fiber laser transmission end; 34. Fiber laser collimating lens; 35. Movable reflection device; 351. Slide rail; 352. Liftable lens mounting groove; 353. Reflection lens; 36. Semiconductor laser transmission end; 37. Semiconductor laser collimating lens; 38. Beam splitter lens; 39. Confocal lens;

[0037] 41. Semiconductor laser beam B; 42. Pulsed fiber laser beam B;

[0038] 51. Displacement sensing device A1; 52. Displacement sensing device A2; 53. Displacement sensing device B1; 54. Displacement sensing device B2. Detailed implementation manners

[0039] The following will detail the implementation manners of the present application in conjunction with the accompanying drawings and embodiments, so as to fully understand how the present application uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly.

[0040] Please refer to Figure 1 , the present invention provides a thin - walled Invar alloy small - deformation mirror welding device based on pulsed laser staggered - step distribution, including a control system 1, a multi - source laser system 2, a pulsed - continuous laser composite welding head A, a pulsed - continuous laser composite welding head B, a mirror displacement monitoring system 5 and a weldment 6. The control system 1 is connected to the multi - source laser system 2 and the mirror displacement monitoring system 5 through connecting wires; the multi - source laser system 2 is used to output a continuous - pulsed composite laser beam, including a semiconductor laser A, a pulsed fiber laser A, a semiconductor laser B, and a pulsed fiber laser B. Among them, the semiconductor laser A and the pulsed fiber laser A are connected to the pulsed - continuous laser composite welding head through transmission optical fibers, and the semiconductor laser B and the pulsed fiber laser B are connected to the pulsed - continuous laser composite welding head B through transmission optical fibers. The semiconductor laser transmission system and the fiber laser transmission system can respectively output parallel semiconductor laser beam 31 and fiber laser beam 32 downward from the semiconductor laser output end 36 and the pulsed fiber laser transmission end 33. Heat input modification: bilateral energy

[0041] The internal structure of the pulsed - continuous laser composite welding head B is the same as that of the pulsed - continuous laser composite welding head A, and the two are symmetrically arranged on both sides of the weldment 6 and are independent of each other, and their spatial postures are respectively controlled by the control system 1.

[0042] The mirror displacement monitoring system 5 is used to monitor the angular deformation of the welded part 6 during the welding process in real time, and includes displacement sensing devices A1, A2, B1, and B2. The displacement sensing devices A1 and A2 are installed on the pulse - continuous laser relative position adjustable welding head A. The displacement sensing devices B1 and B2 are installed on the pulse - continuous laser relative position adjustable welding head B. The displacement sensing devices A1, A2, B1, and B2 calculate the corresponding distances in real time by monitoring the time t when their detection lines are blocked, so as to monitor the deformation amounts on both sides of the welded part 6 in real time. The control system 1 receives the displacement deformation signals on both sides of the welded part 6 in the mirror displacement monitoring system 5 through signal connection lines, and retrieves the relationship between the deformation amount difference solution - multi - source laser process parameters - reflector height in the control system. The control system 1 sends the adjusted multi - source laser process parameters and the height of the movable reflector 35 to the multi - source laser system 2 according to the feedback signals of the deformation amounts on both sides.

[0043] In this embodiment, the laser power ranges that the semiconductor lasers A and B can output are 0 - 2000W, and the laser power ranges that the pulsed fiber lasers A and B can output are 0 - 4000W.

[0044] As Figure 2 shown, the pulse - continuous laser composite welding head A includes a semiconductor laser beam A, a pulsed fiber laser beam A, a pulsed fiber laser transmission end 33, a fiber laser collimating lens 34, a movable reflector 35, a semiconductor laser transmission end 36, a semiconductor laser collimating lens 37, a beam splitter 38, and a confocal lens 39.

[0045] The semiconductor laser beam 31 is connected to the pulse - continuous laser composite welding head through the semiconductor laser transmission end 36, and then reaches the surface of the welded part 6 through the semiconductor laser collimating lens 37, the beam splitter 38, and the confocal lens 39 in sequence; the pulsed fiber laser beam 32 is connected to the pulse - continuous laser composite welding head through the pulsed fiber laser transmission end 33, and then reaches the surface of the welded part 6 through the fiber laser collimating lens 34, the movable reflector 35, the beam splitter 38, and the confocal lens 39 in sequence.

[0046] In this embodiment, the welded part 6 is an Invar alloy thin - plate butt joint structure with dimensions of 100mm×200mm×0.5mm, where 0.5mm is the thickness of the plate, 200mm is the length of the weld, and there are no grooves and gaps. In other embodiments, the welding structure can be of other dimensions.

[0047] The laser welding process parameters are as follows: the set power of semiconductor laser A and semiconductor laser B is 1000 W, the set power of pulsed fiber laser A and pulsed fiber laser B is 1500 W, the pulse frequency is set to 20 Hz, the welding speed is 2.4 m / min, the pulse laser duration is 30 ms, the center of the pulsed fiber laser spot coincides with the center of the semiconductor laser spot, and the angle between the bilateral pulsed - continuous laser beam and the weld plane is 90°. The pulsed fiber laser and the semiconductor laser are combined to carry out laser welding, and the ultra - thin Invar alloy small - deformation mirror welding based on the pulsed laser staggered step distribution is completed.

[0048] As Figure 2 shown, the semiconductor laser transmission system and the pulsed fiber laser transmission system jointly form a multi - source laser system 2. The semiconductor laser transmission system is provided with a semiconductor laser collimating lens 37, a beam - splitting lens 38, and a confocal lens 39 from top to bottom. The three are located on the same center line, and the semiconductor laser beam 31 acts on the surface of the welded part through the semiconductor laser collimating lens 37, the beam - splitting lens 38, and the confocal lens 39. The pulsed fiber laser transmission system includes a fiber laser collimating lens 34, a movable fiber laser reflecting lens 353, a beam - splitting lens 38, and a confocal lens 39 arranged in the pulsed - continuous laser composite welding head 3. The pulsed fiber laser beam 32 passes through the laser collimating lens 34, is reflected by the movable fiber laser mirror 353 and the beam - splitting mirror 38 to the confocal lens 39 and is combined with the semiconductor laser beam to act on the surface of the welded part 6.

[0049] The transmittance of the semiconductor laser collimating lens 37, the beam - splitting lens 38, and the confocal lens 39 for the semiconductor laser beam with a wavelength of 915 nm is 99.99%.

[0050] The transmittance of the fiber laser collimating lens 34 and the confocal lens 39 for the pulsed fiber laser beam with a wavelength of 1064 nm is 99.99%.

[0051] The reflectivity of the fiber laser reflecting lens 353 and the beam - splitting lens 38 for the pulsed fiber laser beam with a wavelength of 1064 nm is 99.9%.

[0052] As Figure 3 、 Figure 4 shown, during the welding process, the mirror displacement monitoring system 5 monitors and measures the deformation amount d A on the A side and the deformation amount d B on the B side of the 0.5 - mm - thick Invar alloy thin plate in real - time, and feeds the deformation amounts on both sides back to the control system 1. The control system 1 solves the difference between the deformation amounts on both sides, and determines parameters such as the pulsed fiber laser power, pulse frequency, pulse laser duration, and relative position of the bilateral pulsed fiber laser beams on both sides according to the difference solution amount.

[0053] For the deformation amount |d on both sides of a 0.5-mm-thick Invar alloy thin plate A -d B When |d < 0.02, symmetric distributed laser mirror welding is adopted; when 0.02 < |d A -d B < 0.05, staggered distributed laser mirror welding is adopted; when 0.05 < |d A -d B < 0.1, single-sided step distributed laser mirror welding is adopted; when 0.1 < |d A -d B < 0.2, double-sided asymmetric step distributed laser mirror welding is adopted.

[0054] The control system 1 adjusts parameters such as pulsed fiber laser power, pulse frequency, and pulsed laser duration by controlling the multi-source laser system 2, and adjusts the relative position of the double-sided pulsed fiber laser beams by controlling the movable reflection device 35. The movable reflection device 35 includes a slide rail 351, a liftable lens mounting groove 352, and a reflection lens 353. To adjust the relative position of the pulsed-continuous laser composite laser, the spatial position of the pulsed fiber laser beam is changed by controlling the lifting of the slide rail 351 and the height of the reflection lens 353. When the reflection lens 353 is moved upward, the pulsed fiber laser beam 32 is reflected by the beam splitter lens 38 to the left side of the confocal lens 39, and the pulsed fiber laser beam 32 moves to the left relative to the semiconductor laser beam 31; when the reflection lens 353 is moved downward, the pulsed fiber laser beam 32 is reflected by the beam splitter lens 38 to the right side of the confocal lens 39, and the pulsed fiber laser beam 32 moves to the right relative to the semiconductor laser beam 31.

[0055] In the case of a small deformation amount of the Invar alloy thin plate, the control system 1 adopts the symmetric distributed laser mirror welding method by controlling the multi-source laser system 2. In the case of a large deformation amount, the control system 1 controls the multi-source laser system 2 and the movable reflection device 35 according to the ratio of the deformation amount on both sides of the Invar alloy thin plate to the thickness of the weldment 6, and performs staggered distributed, single-sided step distributed, and double-sided asymmetric step distributed laser mirror welding methods, achieving the purpose of correcting the deformation on both sides of the weldment 6 during welding by controlling the asymmetric distribution of the heat input amount. After the deformation amount is reduced, the control system 1 restores the double-sided energy distribution mode to symmetric distribution to achieve precise control of the double-sided deformation amount.

[0056] For the ultra-thin Invar alloy small-deformation mirror welding method based on the pulsed laser staggered step distribution, an ultra-thin Invar alloy small-deformation mirror welding device based on the pulsed laser staggered step distribution is adopted. The welding method includes the following steps:

[0057] Step 1: Install and fix an Invar alloy weldment with a thickness of 0.5 mm;

[0058] Step 2: Turn on the mirror displacement monitoring system 5, and ensure the pre-welding deformation through the mirror displacement monitoring system 5;

[0059] Step 3: Adjust the positions of the pulsed - continuous laser composite welding head A and the pulsed - continuous laser composite welding head B according to the weld position, so that they present a mirror distribution relative to the weld;

[0060] Step 4: Input the weldment thickness of 0.5 mm into the control system 1;

[0061] Step 5: Set the pulsed fiber laser power P1 = 1500 W, pulse frequency f = 20 Hz, pulsed laser duration t1 = 30 ms, semiconductor laser power P2 = 1000 W, and welding speed v = 2.4 m / min on both sides through the control panel in the control system 1;

[0062] Step 6: The control system 1 turns on the semiconductor laser A, pulsed fiber laser A, semiconductor laser B, and pulsed fiber laser B, and starts the laser mirror welding operation;

[0063] Step 7: During the welding process, the mirror displacement monitoring system 5 records the deformation of the weldment in real time and feeds it back to the control system 1. The control system 1 solves the difference between the deformation amounts d A and d B dynamically adjusts the parameters according to the difference solution amount, including: pulsed fiber laser power on both sides, pulse frequency, pulsed laser duration, relative position of the bilateral pulsed fiber laser beams, and realizes the rapid switching between symmetric distributed laser mirror welding, staggered distributed laser mirror welding method, unilateral step - distributed laser mirror welding method, and bilateral asymmetric step - distributed laser mirror welding method, so as to ensure that the deformation amount is controlled within the threshold range and complete the welding.

[0064] In summary, the above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification and equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

[0065] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. An ultra-thin Invar alloy small deformation mirror welding device based on pulse laser staggered step distribution, characterized in that: It comprises a control system (1), a multi-source laser system (2), a pulse-continuous laser composite welding head A (3), a pulse-continuous laser composite welding head B (4), a mirror displacement monitoring system (5) and a weldment (6), wherein the control system (1) is connected to the multi-source laser system (2) and the mirror displacement monitoring system (5) respectively via connecting lines; The multi-source laser system (2) is used to output a continuous-pulse composite laser beam, and comprises a semiconductor laser A (21), a pulse fiber laser A (22), a semiconductor laser B (23), and a pulse fiber laser B (24), wherein the semiconductor laser A (21) and the pulse fiber laser A (22) are connected to a pulse-continuous laser composite welding head via a transmission optical fiber, and the semiconductor laser B (23) and the pulse fiber laser B (24) are connected to a pulse-continuous laser composite welding head B (4) via a transmission optical fiber; The pulse-continuous laser composite welding head A (3) comprises a semiconductor laser beam A (31), a pulse fiber laser beam A (32), a pulse fiber laser transmission end (33), a fiber laser collimating lens (34), a movable reflecting device (35), a semiconductor laser transmission end (36), a semiconductor laser collimating lens (37), a beam splitter lens (38), and a confocal lens (39); The internal structure of the pulse-continuous laser hybrid welding head B (4) is the same as that of the pulse-continuous laser hybrid welding head A (3); The mirror displacement monitoring system (5) is used to monitor the deformation of the weldment (6) in real time during the welding process, and comprises a displacement sensing device A1 (51), a displacement sensing device A2 (52), a displacement sensing device B1 (53), and a displacement sensing device B2 (54). The displacement sensing device A1 (51) and the displacement sensing device A2 (52) are installed on a pulse-continuous laser relative position adjustable welding head A; During the welding process, the mirror displacement monitoring system (5) monitors the deformation of the A side of the weldment in real time. A Deformation of side B d B , feeding back the deformation on both sides to the control system (1), the control system (1) performs a difference solution on the deformation on both sides, and determines the pulse fiber laser power, pulse frequency, pulse laser duration, and relative position parameters of the pulse fiber laser beams on both sides according to the difference solution; Amount of deformation on both sides |d A -d B When |d < a, symmetric distributed laser mirror welding is adopted; when a < |d A -d B When |d < b, offset distributed laser mirror welding is adopted; when b < |d A -d B When |d < c, single-sided step distributed laser mirror welding is adopted; when c < |d A -d B When |d < d, double-sided asymmetric step distributed laser mirror welding is adopted, where a < b < c < d; The control system (1) adjusts the pulse fiber laser power, pulse frequency, and pulse laser duration by controlling the multi-source laser system (2), and adjusts the relative positions of the double-sided pulse fiber laser beams by controlling the movable reflection device (35); When the deformation is small, the control system (1) controls the multi-source laser system (2) to adopt a symmetrical distributed laser mirror welding method; In the case of a large deformation, the control system (1) controls the multi-source laser system (2) and the movable reflection device (35) according to the ratio of the deformation to the thickness of the weldment (6) to perform peak-shifted distributed, single-sided step-distributed, and double-sided asymmetric step-distributed laser mirror welding methods, thereby achieving the purpose of correcting the deformation on both sides of the weldment (6) during welding by controlling the asymmetric distribution of energy on both sides. After the deformation is reduced, the control system (1) restores the double-sided energy distribution mode to symmetrical distribution to achieve precise control of the deformation on both sides.

2. The ultra-thin Invar alloy small deformation mirror welding device based on pulse laser staggered step distribution according to claim 1 is characterized in that: The pulse-continuous laser hybrid welding head A (3) and the pulse-continuous laser hybrid welding head B (4) are symmetrically arranged on both sides of the weldment (6) and are independent of each other, and their spatial positions are respectively controlled by a control system (1).

3. The ultra-thin Invar alloy small deformation mirror welding device based on pulse laser staggered step distribution according to claim 1 is characterized in that: The movable reflection device (35) comprises a slide rail (351), a liftable lens mounting groove (352), and a reflection lens (353); the liftable lens mounting groove (352) is used to adjust the height position of the reflection lens (353) through the slide rail (351), thereby controlling the relative position of the pulse fiber laser spot (321) and the semiconductor laser spot (311).

4. The ultra-thin Invar alloy small deformation mirror welding device based on pulse laser staggered step distribution according to claim 1 is characterized in that: The semiconductor laser A (21) and the pulse fiber laser A (22) transmit laser beams to the semiconductor laser transmission end (36) and the pulse fiber laser transmission end (33) respectively through their own transmission optical fibers; The semiconductor laser beam is connected to the pulse-continuous laser composite welding head through the semiconductor laser transmission end (36), and then reaches the workpiece surface through the semiconductor laser collimating lens (37), the beam splitting lens (38), and the confocal lens (39) in sequence; The pulse fiber laser beam is connected to the pulse-continuous laser composite welding head through the pulse fiber laser transmission end (33), and then reaches the workpiece surface through the fiber laser collimating lens (34), the movable reflection device (35), the beam splitting lens (38), and the confocal lens (39) in sequence.

5. A welding method of an ultra-thin Invar alloy small deformation mirror welding device based on a pulsed laser staggered step distribution as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Install and fix the ultra-thin Invar alloy weldment (6); S2: Turn on the mirror displacement monitoring system (5); S3: adjusting the positions of the pulse-continuous laser hybrid welding head A (3) and the pulse-continuous laser hybrid welding head B (4) according to the position of the weld so that they are distributed in a mirror image relative to the weld; S4: Inputting the thickness of the weldment (6) into the control system (1); S5: According to welding requirements, the pulse fiber laser power, pulse frequency, pulse laser duration, semiconductor laser power and welding speed on both sides are set through the control panel in the control system (1); S6: The control system (1) turns on the semiconductor laser A (21), the pulse fiber laser A (22), the semiconductor laser B (23), and the pulse fiber laser B (24), and starts the laser mirror welding operation; S7: During the welding process, the mirror displacement monitoring system (5) records the deformation of the weldment (6) in real time and feeds it back to the control system (1). The control system (1) calculates the difference between the deformations on both sides and dynamically adjusts parameters according to the difference, including: the pulse fiber laser power on both sides, the pulse frequency, the pulse laser duration, and the relative position of the pulse fiber laser beams on both sides, so as to achieve rapid switching between symmetrical distributed laser mirror welding, staggered distributed laser mirror welding, single-sided step distributed laser mirror welding, and double-sided asymmetrical step distributed laser mirror welding, so as to ensure that the deformation is controlled within the threshold range and complete the welding.

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