An underwater multi-wavelength composite laser welding deformation self-adaptive control device and method

Abstract

The present invention discloses an underwater multi-wavelength composite laser welding deformation self-adaptive regulation device and method. The device includes a control system, an underwater multi-wavelength composite laser welding system, a dual-fiber-semiconductor laser composite welding head, and a deformation monitoring system. It is characterized in that the laser beam output by the dual-fiber-semiconductor laser composite welding head acts on the weldment. The semiconductor short-wave laser with a large spot preheats the material, and the fiber long-wave laser performs high-energy deep penetration welding underwater. The two cooperate to enhance the stability of the molten pool. The control system controls the deformed surface by adaptively adjusting the swing parameters of the fiber lasers on both sides, and adjusts the parameters for different degrees of deformation to ensure the reduction of the height of the deformed median plane. The present invention adjusts the swing parameters of the fiber laser beam through underwater multi-wavelength composite welding to change the energy distribution characteristics in the near-weld zone, realizes the real-time optimization of the stress and deformation in the welding process, and solves the problems of post-weld stress concentration, large deformation, and insufficient weld strength in underwater laser welded structural parts.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater laser welding, and in particular to an underwater multi-wavelength composite laser welding deformation self-adaptive regulation device and method. Background Art

[0002] Underwater laser welding has been widely used to repair and connect damaged components and structures in nuclear power plants or underwater structures. Compared with other underwater welding methods, underwater laser welding has many advantages, such as easy control of heat input and high-precision energy transmission for the components to be repaired and welded. In any fusion welding, the bending deformation of the weld caused by rapid heating and cooling is inevitable, and it has an adverse impact on the subsequent assembly process and service life. Therefore, the laser welding energy control technology applied to underwater laser welding urgently needs to be further broken through.

[0003] The fiber-semiconductor composite laser welding technology preheats the material with a large spot of semiconductor short-wavelength laser, melts the material surface, increases the absorption rate of the material to fiber laser, and performs deep penetration welding in combination with infrared laser. Different positions such as concentric circles and eccentric circles can be achieved between multi-wavelength composite laser beams, which can effectively control the self-adaptive distribution of the heat source, improve the weld forming quality, and reduce the post-weld deformation, etc.

[0004] When the laser oscillates during welding, the beam forcibly stirs the molten pool, which is beneficial to refining the weld grains, and thus improving the joint quality. In addition, the energy distribution of the oscillating heat source is more uniform, which can effectively relieve the post-weld stress concentration, improve the reliability and safety of the welded structural parts, and extend their service life. During underwater laser welding, the oscillation of the beam is beneficial to reducing the temperature gradient of the whole welded part, and the underwater cooling and the beam oscillation effect jointly reduce the concentrated distribution of heat on the welded part. Therefore, how to give full play to the advantages of multi-wavelength composite laser, cooperate with the beam oscillation to design an adaptive control device that meets the requirements of underwater laser welding deformation and joint quality, and realize low-deformation and high-strength connection of structural parts is still a problem to be solved for underwater laser welded structural parts. Summary of the Invention

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device, including a control system, an underwater multi-wavelength composite laser welding system, a double fiber-semiconductor laser composite welding head, a deformation monitoring system, a local dry drainage device, and a welded part. The control system is connected to the underwater multi-wavelength composite laser welding system and the deformation monitoring system through signal lines. The underwater multi-wavelength composite laser welding system is used to output a composite laser beam, including a semiconductor laser, a fiber laser A, a fiber laser B, a fixed structure A, and a fixed structure B. Among them, the semiconductor laser, the fiber laser A, and the fiber laser B are connected to the double fiber-semiconductor laser composite welding head through transmission fibers;

[0006] The dual-fiber-semiconductor laser composite welding head includes a fiber laser head A, a fiber laser head B, and a semiconductor laser head. Among them, the semiconductor laser head includes a semiconductor laser transmission end, a semiconductor laser collimating lens, a semiconductor laser beam, and a confocal lens; the fiber laser head A includes a fiber laser transmission end A, a fiber laser collimating lens A, a reflecting lens A, a galvanometer A, a beam splitter A, and a swinging fiber laser beam A; the fiber laser head B includes a fiber laser transmission end B, a fiber laser collimating lens B, a reflecting lens B, a galvanometer B, a beam splitter B, and a swinging fiber laser beam B. Among them, the fiber laser head A and the semiconductor laser head are assembled by bolt connection at the fixed structure A, and the fiber laser head B and the semiconductor laser head are assembled by bolt connection at the fixed structure B. The distance from the fixed structure A to the bottom plane of the end component of the semiconductor laser head is not less than 100 mm, and the distance from the fixed structure B to the top plane of the QBH component of the semiconductor laser head is not less than 100 mm, and the vertical distance between the fixed structure A and the fixed structure B is not less than 150 mm. The reflecting lens A, the reflecting lens B, the beam splitter A, and the beam splitter B form a 45° angle with the horizontal plane and always remain unchanged, and the swinging of the beam is achieved by the deflection of the lenses of the galvanometer A and the galvanometer B;

[0007] The deformation monitoring system is used to monitor the deformation surface of the welded part relative to the entire workbench plane in real time during the welding process, and includes a displacement sensing device and a workbench, and the displacement sensing device is installed inside the base of the workbench.

[0008] Preferably, mounting components are installed at the edges of the fiber laser collimating lens A, the reflecting lens A, the reflecting lens B, and the fiber laser collimating lens B. The mounting components include a first fixing ring and a second fixing ring. A snap ring groove is formed on the surface of the second fixing ring, and a snap ring strip is fixedly installed on the surface of the first fixing ring. The snap ring strip is engaged with the snap ring groove. A clamping groove is formed on the inner side surface. A receiving groove is formed inside the snap ring groove, and a return spring is fixedly installed inside the receiving groove. The other end of the return spring is fixedly connected with a clamping strip, and the clamping strip is engaged and adapted to the clamping groove. Suction cups are fixedly installed on the opposite surfaces of the first fixing ring and the second fixing ring, and the suction cups are pressed and adapted to the lens. The fiber laser collimating lens A, the reflecting lens A, the reflecting lens B, and the fiber laser collimating lens B are stably installed in the laser through the mounting components, preventing the change of the laser transmission direction due to the shaking of the lens. The clamping structure facilitates the replacement of the lens to adapt to different welding requirements.

[0009] Preferably, the semiconductor laser beam acts on the surface of the welded part through a semiconductor laser collimating lens and a confocal lens. The oscillating fiber laser beam A acts on the left side of the circular spot of the semiconductor laser beam through a fiber laser collimating lens A, a reflecting lens A, a galvanometer A, a beam splitting lens A, and a confocal lens. The oscillating fiber laser beam B acts on the right side of the circular spot of the semiconductor laser beam through a fiber laser collimating lens B, a reflecting lens B, a galvanometer B, a beam splitting lens B, and a confocal lens.

[0010] Preferably, the wavelength of the semiconductor laser is 915 nm, and the wavelength of the fiber laser is 1064 nm.

[0011] Preferably, when starting underwater welding, the light output of fiber laser A and fiber laser B is 100 ms slower than that of the semiconductor laser. The semiconductor short-wave laser reduces the energy loss caused by the scattering effect in the underwater environment to ensure the transmission efficiency. Through the thermal effect of the short-wave laser, the fiber long-wave laser efficiently melts the base material and transfers heat. The two work together to prevent excessive cooling and increase the deformation of the welded structural parts.

[0012] Preferably, when the semiconductor laser beam acts on the surface of the welded part, the spot diameter is D, and when the oscillating fiber laser beam A and the oscillating fiber laser beam B act on the surface of the welded part, the spot diameter is d. The relationship between D and d satisfies 2d ≤ D ≤ 3d.

[0013] Preferably, the displacement sensing devices are arranged in an 8-row × 8-column pattern inside the workbench base, and each displacement sensing device is interconnected to monitor 64 points at the bottom of the welded part to form the deformation surface of the welded part.

[0014] Preferably, there is no interference phenomenon between the beams of the oscillating fiber laser beam A and the oscillating fiber laser beam B in the dual-fiber-semiconductor laser composite welding head. The beam splitting lens A and the beam splitting lens B are respectively distributed on the left and right sides inside the dual-fiber-semiconductor laser composite welding head.

[0015] Preferably, the deformation monitoring system monitors the displacement of the welded part in real time and reconstructs the deformation surface, and feeds the deformation surface back to the control system. The control system adaptively adjusts the process parameter factors through the trained PSO-BP neural network algorithm model to control the deformation surface;

[0016] Taking the swing amplitude D, swing frequency f, and spot position S of the oscillating fiber laser beam of fiber laser beam A and fiber laser beam B as inputs, and the height Z of the median surface of the deformation surface as the output, the objective function of the algorithm model is defined as follows:

[0017] Z = F(m × Di, n × fi, q × Si) i = A, B

[0018] In the objective function, the weighting factors are \(m = 0.3\), \(n = 0.2\), and \(q = 0.5\). The update strategy for the objective function \(Z\) is as follows: When \(Z(t + 1)<Z(t)\), welding continues according to \(D\), \(f\), and \(S\) at time \(t + 1\). When \(Z(t + 1)>Z(t)\), the values of \(S\), \(D\), and \(f\) are modified one by one according to the size of the input parameter weighting factor based on the trained PSO - BP neural network algorithm model until \(Z(t + 1)<Z(t)\).

[0019] The present invention also provides a method for adaptive control of underwater multi - wavelength composite laser welding deformation. Using the underwater multi - wavelength composite laser welding deformation adaptive control device, it includes the following steps:

[0020] Step 1: Before welding, the surface of the welded part is polished with metallographic sandpaper, then soaked and cleaned with absolute ethanol at room temperature, and then placed on the bottom plate in the water tank and clamped.

[0021] Step 2: Adjust the position of the double - fiber - semiconductor laser composite welding head according to the weld position. Set the power of the oscillating fiber laser on both sides, the power of the semiconductor laser, the oscillation frequency, the spot position \(S\) of the oscillating fiber laser beam, the oscillation trajectory, and the welding speed through the control system according to the thickness of the welded part.

[0022] Step 3: The control system turns on the semiconductor laser, the oscillating fiber laser A, and the oscillating fiber laser B. Before starting the underwater laser welding operation, stay at the welding starting point for 10 s and keep high - pressure air and argon flowing in to drain the moisture and form a relatively stable protection environment.

[0023] Step 4: During the welding process, the deformation monitoring system monitors the deformation amount of the welded part in real time and feeds it back to the control system. The control system extracts the height \(Z\) of the median surface of the deformation surface and dynamically adjusts the parameters according to the value of \(Z\), including: the swing amplitude \(D\) of the fiber laser beam A and the fiber laser beam B, the swing frequency \(f\), and the spot position \(S\) of the oscillating fiber laser beam. Modify \(S\), \(D\), and \(f\) one by one according to the size of the input parameter weighting factor based on the trained PSO - BP neural network algorithm model to ensure that \(Z(t + 1)<Z(t)\), so as to ensure that the deformation amount is controlled within the threshold range and complete the welding. The beneficial effects of this application compared with the prior art are:

[0024] The underwater multi-wavelength composite laser welding deformation self-adaptive control device and method provided by the present invention include a control system, an underwater multi-wavelength composite laser welding system, a dual-fiber-semiconductor laser composite welding head, a deformation monitoring system, etc. It can solve problems existing in the existing underwater laser welding technology, such as post-weld stress concentration, large deformation amplitude in thin-plate welding, insufficient performance of welded joints, and unstable processing quality. Moreover, it has a high degree of control integration and good operability. The combination of multi-wavelength lasers can improve welding efficiency and weld quality, monitor the deformed surface in real time, and adjust the swing amplitude, swing frequency of the fiber lasers on both sides, and the spot position of the swinging fiber laser beam; ensure the position of the semiconductor laser beam, and greatly improve the self-adaptive control of underwater laser welding for welding deformation of different plates by adjusting the swing parameters of the fiber laser beams on both sides, which is of great significance for realizing high-efficiency and high-quality welding of underwater laser welding structural parts.

[0025] The present invention provides an underwater multi-wavelength composite laser welding deformation self-adaptive control device. It has the following beneficial effects:

[0026] The underwater multi-wavelength composite laser welding deformation self-adaptive control device and method provided by the present invention include a control system, an underwater multi-wavelength composite laser welding system, a dual-fiber-semiconductor laser composite welding head, a deformation monitoring system, etc. It can solve problems existing in the existing underwater laser welding technology, such as post-weld stress concentration, large deformation amplitude in thin-plate welding, insufficient performance of welded joints, and unstable processing quality. Moreover, it has a high degree of control integration and good operability. The combination of multi-wavelength lasers can improve welding efficiency and weld quality, monitor the deformed surface in real time, and adjust the swing amplitude, swing frequency of the fiber lasers on both sides, and the spot position of the swinging fiber laser beam; ensure the position of the semiconductor laser beam, and greatly improve the self-adaptive control of underwater laser welding for welding deformation of different plates by adjusting the swing parameters of the fiber laser beams on both sides, which is of great significance for realizing high-efficiency and high-quality welding of underwater laser welding structural parts. Brief Description of the Drawings

[0027] Figure 1 It is a schematic diagram of an underwater multi-wavelength composite laser welding deformation self-adaptive control device of the present invention;

[0028] Figure 2 It is a schematic diagram of the dual-fiber-semiconductor laser composite welding head of the present invention;

[0029] Figure 3 It is a schematic diagram of the positions of the dual-fiber-semiconductor laser beams and the beam travel trajectories of the present invention;

[0030] Figure 4 It is a schematic diagram of the appearance of the mounting component of the present invention;

[0031] Figure 5 It is a partial sectional view of the mounting component of the present invention;

[0032] Figure 6 This is an enlarged schematic view of part A of the present invention.

[0033] In the figure: 1, control system; 2, underwater multi-wavelength composite laser welding system; 21, fiber laser A; 22, semiconductor laser; 23, fiber laser B; 3, double fiber-semiconductor laser composite welding head; 31, fiber laser transmission end A; 311, fiber laser collimating lens A; 312, reflecting lens A; 313, beam splitting lens A; 314, oscillating fiber laser beam A; 32, semiconductor laser transmission end; 321, semiconductor laser collimating lens; 322, confocal lens; 323, semiconductor laser beam; 33, fiber laser transmission end B; 331, fiber laser collimating lens B; 332, reflecting lens B; 333, beam splitting lens B; 334, oscillating fiber laser beam B; 34, galvanometer A; 35, galvanometer B; 36, fixing structure A; 37, fixing structure B; 38, bottom plane of the end assembly of the semiconductor laser head; 39, top plane of the QBH assembly of the semiconductor laser head; 4, deformation monitoring system; 41, workbench; 42, displacement sensing device; 5, weldment; 6, local dry drainage device; 7, installation assembly; 71, first fixing ring; 72, second fixing ring; 73, snap ring strip; 74, snap ring groove; 75, clamping groove; 76, clamping strip; 77, receiving groove; 78, return spring; 79, suction cup. Specific embodiments

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for purposes of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application, and to enable those of ordinary skill in the art to understand the invention and design various embodiments with various modifications suitable for specific purposes.

[0035] The first embodiment is as Figure 1As shown in the figure, the present invention provides a technical solution: an underwater multi-wavelength composite laser welding deformation self-adaptive control device, which includes an underwater multi-wavelength composite laser welding system 2, a deformation monitoring system 4, and a dual-fiber-semiconductor laser composite welding head 3 connected to the control system through signal lines. The underwater multi-wavelength composite laser welding system 2 is used to output a composite laser beam. The underwater multi-wavelength composite laser welding system 2 includes a semiconductor laser 22, a fiber laser A 21, and a fiber laser B. Among them, the semiconductor laser 22, the fiber laser A 21, and the fiber laser B are independent of each other and are connected to the dual-fiber-semiconductor laser composite welding head 3 through transmission fibers. The semiconductor laser transmission system and the fiber laser transmission system can respectively output parallel semiconductor laser beams 323 and fiber laser beams downward from the dual-fiber-semiconductor laser composite welding head 3. When underwater welding starts, the light output of fiber laser A and fiber laser B is 100 ms slower than that of the semiconductor laser. The semiconductor short-wave laser reduces the energy loss caused by the scattering effect of the underwater environment to ensure the transmission efficiency. Through the thermal effect of the short-wave laser, the fiber long-wave laser efficiently melts the base material and transfers heat. The two work together to prevent excessive cooling and increase the deformation of the welded structural parts. The deformation monitoring system 4 is used to monitor the deformation surface of the welded part 5 relative to the entire workbench 41 plane in real time during the welding process, including a displacement sensing device 42 and a workbench 41. The displacement sensing device 42 is installed inside the base of the workbench 41. The displacement sensing devices 42 are arranged in an 8-row × 8-column manner inside the base of the workbench 41, and each displacement sensing device 42 is interconnected to monitor 64 points at the bottom of the welded part 5 to form the deformation surface of the welded part 5.

[0036] In this embodiment, the laser power range that the semiconductor laser 22 can output is 0 to 4000 W, and the laser power range that the fiber laser can output is 0 to 6000 W.

[0037] The second embodiment, on the basis of the first embodiment, please refer to Figures 2 to 6As shown in the figure, the dual-fiber-semiconductor laser composite welding head 3 includes a fiber laser head A, a fiber laser head B, a semiconductor laser head, a fixing structure A 36, and a fixing structure B 37. Among them, the semiconductor laser head includes a semiconductor laser transmission end 32, a semiconductor laser collimating lens 321, a semiconductor laser beam 323, and a confocal lens 322; the fiber laser head A includes a fiber laser transmission end A 31, a fiber laser collimating lens A 311, a reflecting lens A 312, a galvanometer A 34, a beam splitting lens A 313, and a swinging fiber laser beam A 314; the fiber laser head B includes a fiber laser transmission end B 33, a fiber laser collimating lens B 331, a reflecting lens B 332, a galvanometer B 35, a beam splitting lens B 333, and a swinging fiber laser beam B 334. Among them, the fiber laser head A and the semiconductor laser head are assembled by bolt connection at the fixing structure A 36, and the fiber laser head B and the semiconductor laser head are assembled by bolt connection at the fixing structure B 37. The distance from the fixing structure A 36 to the bottom plane 38 of the end component of the semiconductor laser head is not less than 100 mm, the distance from the fixing structure B 37 to the top plane 39 of the QBH component of the semiconductor laser head is not less than 100 mm, and the vertical distance between the fixing structure A 36 and the fixing structure B 37 is not less than 150 mm. The reflecting lens A 312, the reflecting lens B 332, the beam splitting lens A 313, and the beam splitting lens B 333 form an angle of 45° with the horizontal plane and always remain unchanged. The swinging of the beam is achieved by the deflection of the lenses of the galvanometer A 34 and the galvanometer B 35; the semiconductor laser beam 323 acts on the surface of the weldment 5 through the semiconductor laser collimating lens 321 and the confocal lens 322. The swinging fiber laser beam A 314 acts on the left side of the circular spot of the semiconductor laser beam 323 through the fiber laser collimating lens A 311, the reflecting lens A 312, the galvanometer A 34, the beam splitting lens A 313, and the confocal lens 322. The swinging fiber laser beam B 334 acts on the right side of the circular spot of the semiconductor laser beam 323 through the fiber laser collimating lens B 331, the reflecting lens B 332, the galvanometer B 35, the beam splitting lens B 333, and the confocal lens 322.

[0038] Installation components 7 are installed at the edges of the fiber laser collimating lens A311, the reflecting lens A312, the reflecting lens B332, and the fiber laser collimating lens B331. The installation component 7 includes a first fixing ring 71 and a second fixing ring 72. A snap ring groove 74 is formed on the surface of the second fixing ring 72. A snap ring strip 73 is fixedly installed on the surface of the first fixing ring 71. The snap ring strip 73 is engaged with the snap ring groove 74. A clamping groove 75 is formed on the inner side surface of 73. A receiving groove 77 is formed inside the snap ring groove 74. A return spring 78 is fixedly installed inside the receiving groove 77. The other end of the return spring 78 is fixedly connected to a clamping strip 76. The clamping strip 76 is engaged and adapted with the clamping groove 75. Suction cups 79 are fixedly installed on the opposite surfaces of the first fixing ring 71 and the second fixing ring 72. The suction cups 79 are pressed and adapted with the lens. When the snap ring strip 73 is inserted into the snap ring groove 74, the return spring 78 contracts. When the clamping groove 75 reaches a suitable position, the elastic force of the return spring 78 will push the clamping strip 76, causing the clamping strip 76 to be snapped into the clamping groove 75, thereby firmly clamping the first fixing ring 71 and the second fixing ring 72 together. At this time, the suction cups 79 tightly adsorb on the lens, realizing stable fixation of the lens, ensuring stable installation of the lens in the laser, avoiding shaking and changing the laser transmission direction. The clamping structure facilitates the replacement of the lens to adapt to different welding requirements.

[0039] The changes in the spot positions of the fiber laser beam A and the fiber laser beam B acting on the surface of the weldment 5 and the changes in the swinging trajectories of the beams are both achieved through the deflection of the galvanometer A34 and the galvanometer B35. During this process, the reflecting lens A312, the beam splitter A313, the reflecting lens B332, and the beam splitter B333 all remain in their original positions unchanged.

[0040] When the semiconductor laser beam 323 acts on the surface of the weldment 5, the spot diameter is D. When the swinging fiber laser beam A314 and the swinging fiber laser beam B334 act on the surface of the weldment 5, the spot diameter is d. The relationship between D and d satisfies 2d ≤ D ≤ 3d.

[0041] There is no interference phenomenon between the swinging fiber laser beam A314 and the swinging fiber laser beam B334 in the dual-fiber-semiconductor laser composite welding head 3. The beam splitters A313 and B333 are respectively distributed on the left and right sides inside the dual-fiber-semiconductor laser composite welding head 3.

[0042] In this embodiment, the weldment 5 is a butt joint structure of a TC4 titanium alloy flat plate with dimensions of 300 mm × 100 mm × 3 mm. Among them, 3 mm is the thickness of the plate, 300 mm is the length of the weld, and 100 mm is the width of the weld, without grooves and gaps. In other embodiments, the welding structure can be of other dimensions.

[0043] The process parameters of laser welding are as follows: the set power of the semiconductor laser 22 is 1200 W, the set powers of the fiber laser A 21 and the fiber laser B are 1600 W, the welding speed is 1.8 m / min. The center of the fiber laser A spot is to the left of the center of the semiconductor laser spot, and the center of the fiber laser B spot is to the right of the center of the semiconductor laser spot. The swing trajectories of the fiber laser beams A and B are set to be circular. The double fiber lasers and the semiconductor laser are combined to carry out underwater laser welding, and underwater laser welding with adaptive regulation of multi-wavelength composite laser energy is completed.

[0044] The transmittance of the semiconductor laser collimating lens 321, the beam splitter lens A 313, the beam splitter lens B 333, and the confocal lens 322 for the semiconductor laser beam 323 with a wavelength of 915 nm is 99.99%.

[0045] The transmittance of the fiber laser collimating lens and the confocal lens 322 for the fiber laser beam with a wavelength of 1064 nm is 99.99%.

[0046] The reflectivity of the fiber laser reflection lens and the beam splitter for the fiber laser beam with a wavelength of 1064 nm is 99.9%.

[0047] During the welding process, the deformation displacement monitoring system monitors and measures the deformation of the 3-mm-thick TC4 titanium alloy thin plate in real time and feeds it back to the control system 1. The control system 1 adaptively adjusts the process parameter factors through the trained PSO-BP neural network algorithm model, thereby regulating the deformed surface.

[0048] Taking the swing amplitude D, swing frequency f, and the spot position S of the swinging fiber laser beam of the fiber laser beam A and the fiber laser beam B as inputs, and the height Z of the median surface of the deformed surface as the output, the objective function of the algorithm model is defined as follows:

[0049] Z = F(m×Di, n×fi, q×Si) i = A, B

[0050] In the objective function, the weighting factors are m = 0.3, n = 0.2, q = 0.5. The update strategy of the objective function Z is as follows: when Z(t + 1) < Z(t), continue welding according to D, f, and S at the (t + 1)-th moment; when Z(t + 1) > Z(t), modify the values of S, D, and f one by one according to the size of the input parameter weighting factors according to the trained PSO-BP neural network algorithm model until Z(t + 1) < Z(t).

[0051] The magnitude of the weighting factor is associated with the amount of deformation. When the deformation amount of the TC4 titanium alloy thin plate is small, the control system 1 preferentially regulates the process parameters with smaller weighting factor parameters and preferentially adjusts the swing amplitude D and the swing frequency f. When the deformation amount of the TC4 titanium alloy thin plate is large, the control system 1 preferentially regulates the process parameters with larger weighting factor parameters and preferentially adjusts the spot position S of the swinging fiber laser beam.

[0052] An underwater multi-wavelength composite laser welding deformation adaptive control method uses an underwater multi-wavelength composite laser welding deformation adaptive control device, including the following steps:

[0053] Step 1: Before welding, polish the surface of the 3mm TC4 titanium alloy weldment 5 with metallographic sandpaper, then soak and clean it with anhydrous ethanol at room temperature, and then place it on the bottom plate in the water tank and clamp it.

[0054] Step 2: Adjust the position of the double fiber-semiconductor laser composite welding head 3 according to the weld position. Through the control system 1, set the swing fiber laser power on both sides to 1600W, the semiconductor laser power to 1200W, the swing frequency f = 60Hz, the center of the swing fiber laser beam spot on both the left and right sides and the center of the semiconductor laser beam 323 spot to be 50μm, the swing trajectory to be circular, and the welding speed to be 1.8m / min.

[0055] Step 3: The control system 1 turns on the semiconductor laser 22, the swing fiber laser A21, and the swing fiber laser B. Before starting the underwater laser welding operation, stay at the welding starting point for 10s and keep high-pressure air and argon flowing in to drain the moisture and form a relatively stable protection environment.

[0056] Step 4: During the welding process, the deformation monitoring system 4 monitors the deformation amount of the weldment 5 in real time and feeds it back to the control system 1. The control system 1 extracts the median surface height Z of the deformed surface and dynamically adjusts the parameters according to the magnitude of the Z value, including: the swing amplitude D, the swing frequency f, and the spot position S of the swing fiber laser beam of the fiber laser beam A and the fiber laser beam B. According to the trained PSO-BP neural network algorithm model, modify S, D, and f one by one according to the magnitude of the input parameter weighting factor to ensure that Z(t + 1) < Z(t), so as to ensure that the deformation amount is controlled within the threshold range and complete the welding.

[0057] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art and related fields without creative work shall fall within the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art without special description and limitation.

Claims

1. An underwater multi-wavelength composite laser welding deformation self-adaptive control device, characterized in that, It includes a control system (1), an underwater multi-wavelength composite laser welding system (2), a dual-fiber-semiconductor laser composite welding head (3), a deformation monitoring system (4), a weldment (5), and a local dry drainage device (6). The control system (1) is connected to the underwater multi-wavelength composite laser welding system (2) and the deformation monitoring system (4) through signal lines. The underwater multi-wavelength composite laser welding system (2) is used to output a composite laser beam, and includes a fiber laser A (21), a semiconductor laser (22), and a fiber laser B (23). Among them, the semiconductor laser (22), the fiber laser A (21), and the fiber laser B (23) are connected to the dual-fiber-semiconductor laser composite welding head (3) through transmission fibers. The dual-fiber-semiconductor laser composite welding head (3) includes a fiber laser head A, a fiber laser head B, a semiconductor laser head, a fixing structure A (36), and a fixing structure B (37). Among them, the semiconductor laser head includes a semiconductor laser transmission end (32), a semiconductor laser collimating lens (321), a semiconductor laser beam (323), and a confocal lens (322). The fiber laser head A includes a fiber laser transmission end A (31), a fiber laser collimating lens A (311), a reflecting lens A (312), a galvanometer A (34), a beam splitting lens A (313), and a swinging fiber laser beam A (314). The fiber laser head B includes a fiber laser transmission end B (33), a fiber laser collimating lens B (331), a reflecting lens B (332), a galvanometer B (35), a beam splitting lens B (333), and a swinging fiber laser beam B (334). Among them, the fiber laser head A and the semiconductor laser head are assembled by bolt connection at the fixing structure A (36), and the fiber laser head B and the semiconductor laser head are assembled by bolt connection at the fixing structure B (37). The distance between the fixing structure A (36) and the bottom plane of the end component of the semiconductor laser head (38) is not less than 100 mm, and the distance between the fixing structure B (37) and the top plane of the QBH component of the semiconductor laser head (39) is not less than 100 mm. Moreover, the vertical distance between the fixing structure A (36) and the fixing structure B (37) is not less than 150 mm. The reflecting lens A (312), the reflecting lens B (332), the beam splitting lens A (313), and the beam splitting lens B (333) form an angle of 45° with the horizontal plane and always remain unchanged. The swinging of the beam is achieved by the deflection of the lenses of the galvanometer A (34) and the galvanometer B (35). The deformation monitoring system (4) is used to monitor the deformation surface of the weldment (5) relative to the plane of the entire workbench (41) in real time during the welding process. The deformation monitoring system (4) includes a displacement sensing device (42) and a workbench (41), and the displacement sensing device (42) is installed inside the base of the workbench (41).

2. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that Installation components (7) are installed at the edges of the fiber laser collimating lens A (311), reflecting lens A (312), reflecting lens B (332), and fiber laser collimating lens B (331). The installation component (7) includes a first fixing ring (71) and a second fixing ring (72). A snap ring groove (74) is formed on the surface of the second fixing ring (72). A snap ring strip (73) is fixedly installed on the surface of the first fixing ring (71). The snap ring strip (73) is engaged with the snap ring groove (74). A clamping groove (75) is formed on the inner side surface of the (73). A receiving groove (77) is formed inside the snap ring groove (74). A return spring (78) is fixedly installed inside the receiving groove (77). The other end of the return spring (78) is fixedly connected to a clamping strip (76). The clamping strip (76) is engaged and adapted with the clamping groove (75). Suction cups (79) are fixedly installed on the opposite surfaces of the first fixing ring (71) and the second fixing ring (72). The suction cups (79) are pressed and adapted to the lens.

3. An underwater multi-wavelength composite laser welding deformation self-adaptive control device according to claim 1, characterized in that, The semiconductor laser beam (323) acts on the surface of the weldment (5) through the semiconductor laser collimating lens (321) and the confocal lens (322). The oscillating fiber laser beam A (314) acts on the left side of the circular spot of the semiconductor laser beam (323) through the fiber laser collimating lens A (311), reflecting lens A (312), galvanometer A (34), beam splitter lens A (313), and confocal lens (322). The oscillating fiber laser beam B (334) acts on the right side of the circular spot of the semiconductor laser beam (323) through the fiber laser collimating lens B (331), reflecting lens B (332), galvanometer B (35), beam splitter lens B (333), and confocal lens (322).

4. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that, The wavelength of the semiconductor laser beam (323) is 915 nm, and the wavelengths of the oscillating fiber laser beam A (314) and the oscillating fiber laser beam B (334) are 1064 nm.

5. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that When underwater welding starts, the light output of the fiber laser A (21) and the fiber laser B (23) is 100 ms slower than that of the semiconductor laser (22). The semiconductor short-wave laser reduces the energy loss caused by the scattering effect in the underwater environment to ensure the transmission efficiency. Through the thermal effect of the short-wave laser, the fiber long-wave laser efficiently melts the base material and transfers heat. The two work together to prevent excessive cooling and increase the deformation of the welded structural parts.

6. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that, The spot diameter of the semiconductor laser beam (323) when acting on the surface of the weldment (5) is D, and the spot diameters of the oscillating fiber laser beam A (314) and the oscillating fiber laser beam B (334) when acting on the surface of the weldment (5) are d. 2d ≤ D ≤ 3d is satisfied between D and d.

7. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that, The displacement sensing devices (42) are arranged in an 8-row × 8-column pattern inside the base of the workbench (41). The displacement sensing devices (42) are interconnected to monitor 64 points at the bottom of the weldment (5) to form the deformation surface of the weldment (5).

8. An underwater multi-wavelength composite laser welding deformation self-adaptive regulation device according to claim 1, characterized in that, There is no interference phenomenon between the swinging fiber laser beam A (314) and the swinging fiber laser beam B (334) in the dual-fiber-semiconductor laser composite welding head (3). The beam splitting lens A (313) and the beam splitting lens B (333) are respectively distributed on the left and right sides inside the dual-fiber-semiconductor laser composite welding head (3). During the welding process, the deformation monitoring system (4) monitors the displacement of the welded part (5) in real time and reconstructs the deformed surface, and feeds back the deformed surface to the control system (1). The control system (1) adaptively adjusts the swinging parameters of the swinging fiber laser beam A (314) and the swinging fiber laser beam B (334) through the trained PSO-BP neural network algorithm model, so as to control the deformed surface. Taking the swinging amplitude D, swinging frequency f, and the spot position S of the swinging fiber laser beam of the swinging fiber laser beam A (314) and the swinging fiber laser beam B (334) as inputs, and taking the median surface height Z of the deformed surface as the output, the objective function of the algorithm model is defined as follows: Z = F(m×Di, n×fi, q×Si) i = A, B In the objective function, the weighting factors are m = 0.3, n = 0.2, and q = 0.

5. The update strategy of the objective function Z is as follows: when Z(t + 1) < Z(t), continue welding according to D, f, and S at the (t + 1)th moment; when Z(t + 1) > Z(t), according to the trained PSO-BP neural network algorithm model, modify the values of S, D, and f one by one according to the size of the input parameter weighting factors until Z(t + 1) < Z(t).

9. An adaptive control method for underwater multi-wavelength composite laser welding deformation, characterized in that, When using an underwater multi-wavelength composite laser welding deformation adaptive control device described in any one of claims 1-8, it includes the following steps: Step 1: Before welding, polish the surface of the welded part (5) with metallographic sandpaper, then soak and clean it with absolute ethanol at room temperature, and then place it on the bottom plate in the water tank and clamp it. Step 2: Adjust the position of the dual-fiber-semiconductor laser composite welding head (3) according to the weld position, and set the swinging fiber laser power, semiconductor laser power, swinging amplitude D, swinging frequency f, the spot position S of the swinging fiber laser beam, the swinging trajectory, and the welding speed on both sides through the control system (1) according to the thickness of the welded part (5). Step 3: The control system (1) turns on the semiconductor laser (22), the swinging fiber laser A (21), and the swinging fiber laser B (23). Before starting the underwater laser welding operation, stay at the welding starting point for 10 s and keep high-pressure air and argon gas flowing in to drain the moisture and form a relatively stable protection environment. Step 4: During the welding process, the deformation monitoring system (4) monitors the deformation amount of the welded part (5) in real time and feeds it back to the control system (1). The control system (1) extracts the median surface height Z of the deformed surface, and dynamically adjusts the parameters according to the magnitude of the Z value, including: the swing amplitude D, the swing frequency f, and the spot position S of the swinging fiber laser beam of the fiber laser beam A and the fiber laser beam B. According to the trained PSO-BP neural network algorithm model, S, D, and f are modified one by one according to the magnitude of the input parameter weighting factor to ensure that Z(t + 1) < Z(t), so as to ensure that the deformation amount is controlled within the threshold range and complete the welding.

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