Ultrasonic-Assisted Underwater Laser-FCAW Hybrid Wet Welding Device and Method

Abstract

The present invention discloses an ultrasonic-assisted underwater laser-FCAW hybrid wet welding device and method, which includes a laser-FCAW hybrid welding equipment composed of a laser welding mechanism and a flux-cored wire arc welding mechanism, as well as an ultrasonic assistance mechanism. The laser welding mechanism and the ultrasonic assistance mechanism are coaxially arranged. During the welding process, the ultrasonic radiation force generated by the ultrasonic assistance mechanism acts on the bubbles on the surface of the welded workpiece, delaying the floating time of the bubbles, reducing the floating frequency of the bubbles, and at the same time weakening the repulsive effect of the buoyancy of the bubbles on the droplet transfer, thereby improving the quality of the welded joint. The present invention adopts the above ultrasonic-assisted underwater laser-FCAW hybrid wet welding device and method, controls the bubbles through ultrasonic vibration and the underwater laser-FCAW coupling effect, improves the arc stability, promotes the droplet transfer, thereby improving the stability of the underwater wet welding process and achieving the purpose of improving the quality of the underwater wet welding joint.

Description

Technical Field

[0001] The present invention relates to an underwater welding technology, and particularly to an ultrasonic-assisted underwater laser-FCAW composite wet welding device and method. Background Art

[0002] With the strong demand for marine resources and deep-sea oil and gas energy, underwater welding, as an essential key technology for developing the ocean, exploiting undersea oil, and assembling and repairing offshore oil platforms, undersea oil pipelines, and nuclear power plant pools, etc., in the construction and repair of steel structures, has always been the focus of ocean engineering construction in various countries.

[0003] Common underwater welding methods include three categories: underwater wet welding, local dry welding, and dry welding. Among them, underwater wet welding has become the most common underwater repair method due to its economic efficiency and convenient operation. However, at present, the stability and controllability of the wet welding process and quality are relatively poor, and it cannot meet the growing technical requirements. Summary of the Invention

[0004] To solve the above problems, the present invention provides an ultrasonic-assisted underwater laser-FCAW composite wet welding device and method, which combines ultrasonic technology with underwater laser-FCAW composite wet welding technology, and regulates the laser-FCAW composite welding process through the ultrasonic effect generated during the ultrasonic vibration process, improving the stability of the underwater laser-FCAW composite wet welding process and achieving the purpose of improving the quality of underwater wet welding joints.

[0005] To achieve the above object, the present invention provides an ultrasonic-assisted underwater laser-FCAW composite wet welding device, including a laser-FCAW composite welding device composed of a laser welding mechanism and a flux-cored wire arc welding mechanism, and an ultrasonic assistance mechanism. The laser welding mechanism is coaxially arranged with the ultrasonic assistance mechanism, and is used to utilize the ultrasonic radiation force generated by the ultrasonic assistance mechanism to act on the bubbles on the surface of the welding workpiece during the welding process, delaying the floating time of the bubbles, reducing the floating frequency of the bubbles, and at the same time weakening the repulsive effect of the buoyancy of the bubbles on the droplet transfer, thereby improving the quality of the welding joint.

[0006] Preferably, the laser welding mechanism and the flux-cored wire arc welding mechanism are respectively arranged at both ends of the traveling mechanism through the clamping mechanism; the laser welding mechanism includes a laser head.

[0007] The ultrasonic assistance mechanism includes a waterproof housing fixed to the front end of the laser head, an ultrasonic transducer and an ultrasonic horn fixedly arranged in the waterproof housing from top to bottom in sequence, and a copper tube sequentially passing through the axial inner hole of the ultrasonic transducer and the axial inner hole of the ultrasonic horn. The copper tube is coaxially arranged with the laser head and is perpendicularly arranged with the welding workpiece.

[0008] The copper pipe is communicated with one end of a ventilation pipe connected to the waterproof housing, and the other end of the ventilation pipe is communicated with a gas supply mechanism.

[0009] Preferably, the rear end of the copper pipe is flush with the rear end of the ultrasonic transducer, and an inflation chamber is formed among the rear end of the copper pipe, the rear end of the ultrasonic transducer and the waterproof housing, and the inflation chamber is communicated with the ventilation pipe.

[0010] Preferably, the ultrasonic transducer is electrically connected to an ultrasonic power supply;

[0011] The laser head is connected to a laser generator through an optical fiber;

[0012] The laser welding mechanism is electrically connected to the positive pole of a welding power supply, and the negative pole of the welding power supply is electrically connected to the welded workpiece.

[0013] Preferably, the laser welding mechanism includes a welding torch, a conductive rod and a conductive nozzle which are sequentially connected to the clamping mechanism, and a flux-cored wire passes through the welding torch and the conductive rod in sequence and then passes out through the conductive nozzle;

[0014] The angle between the central axis of the conductive nozzle and the welded workpiece is 30-60°, and the vertical distance between the conductive nozzle and the welded workpiece is between 10 mm and 20 mm;

[0015] The horizontal distance between the front end of the conductive nozzle and the front end of the copper pipe is between 5 mm and 10 mm.

[0016] Preferably, the vertical distance between the laser head and the welded workpiece is between 300 mm and 500 mm;

[0017] The vertical distance between the front end of the ultrasonic horn and the welded workpiece is between 30 mm and 150 mm.

[0018] Preferably, the welding parameters of the ultrasonic assistance mechanism are: ultrasonic frequency: 20-30 kHz, ultrasonic power: 100-400 W, ultrasonic amplitude: 3-50 μm.

[0019] Preferably, the welding parameters of the laser welding mechanism are: laser energy: 1.5-3 kW.

[0020] Preferably, the welding parameters of the flux-cored wire mechanism are: welding voltage: 25-40 V, welding current: 150-250 A;

[0021] An ultrasonic-assisted underwater laser-FCAW hybrid wet welding method includes the following steps:

[0022] Step 1: Installation and debugging

[0023] Step 1.1: Installation

[0024] Respectively set the laser welding mechanism and the flux-cored wire arc welding mechanism with an ultrasonic assisting mechanism on the clamping mechanisms at both ends of the traveling mechanism;

[0025] Step 1.2: Debugging

[0026] Adjust the relative distance and angle between the laser welding mechanism and the flux-cored wire arc welding mechanism, as well as the distance and angle of both with respect to the welding workpiece through the clamping mechanism and the traveling mechanism, until the angle between the central axis of the contact tip and the welding workpiece is 30° - 60°, the vertical distance between the contact tip and the welding workpiece is between 10 mm and 20 mm; the horizontal distance between the contact tip and the copper tube is between 5 mm and 10 mm; the vertical distance between the laser head and the welding workpiece is between 300 mm and 500 mm; the vertical distance between the front end of the ultrasonic horn and the welding workpiece is between 30 mm and 150 mm;

[0027] Step 2: Start the traveling mechanism, control the overall running speed at 2.5 - 8 m / min, simulate a traveling trajectory once, and after confirming smooth running without obstacles, reset;

[0028] Step 3: Turn on the ultrasonic power supply, and after the ultrasonic assisting mechanism works stably, turn on the gas supply mechanism to supply gas into the waterproof housing until the water in the copper tube is drained;

[0029] Step 4: Input welding parameters;

[0030] Step 5: Start the welding power supply and the laser generator in sequence. The flux-cored wire of the flux-cored wire arc welding mechanism contacts the welding workpiece to form a circuit, generating an arc. The laser generator transmits the laser to the laser head through the optical fiber, and the laser is radiated to the welding workpiece by means of the laser head. At the same time, underwater wet welding is carried out under the assistance of the ultrasonic assisting mechanism;

[0031] Step 6: After welding is completed, turn off the traveling mechanism, the laser generator, the welding power supply, the ultrasonic power supply and the gas supply mechanism in sequence.

[0032] The present invention has the following beneficial effects:

[0033] Adjust the laser welding mechanism and the flux-cored wire arc welding mechanism to the set welding position through the clamping mechanism and the traveling mechanism, realize the coupling of the laser welding process and the self-shielded flux-cored wire arc welding process, and regulate the underwater laser - FCAW composite wet welding process under the assistance of the ultrasonic system, so as to achieve the purpose of improving the quality of underwater wet welding joints. Specifically:

[0034] During the welding process, the ultrasonic radiation force generated by ultrasonic vibration acts on the bubbles on the surface of the welded workpiece, delaying the floating time of the bubbles, providing a stable gas environment for laser-FCAW hybrid welding, reducing the absorption of laser energy by water, and improving the utilization rate of laser energy;

[0035] At the same time, the ultrasonic action reduces the floating frequency of the bubbles, weakens the disturbance effect of the bubbles, resulting in a reduction in the degree of arc fluctuation, thereby improving arc stability. Moreover, under the synergistic action of ultrasonic and laser, the repulsive effect of the buoyancy of the bubbles on the droplet transfer is weakened, and the droplets are transferred in a stable manner, which is beneficial to improving the stability of the welding process;

[0036] In addition, the acoustic streaming effect generated by ultrasonic vibration can make the water around the welded workpiece form a stable jet flow, which can effectively reduce the influence of the water flow disturbance at the welded workpiece on the welding quality.

[0037] Therefore, the present invention can effectively improve the stability of the underwater laser-FCAW hybrid wet welding process and achieve the purpose of improving the quality of underwater wet welding joints.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Brief Description of the Drawings

[0039] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0040] Figure 2 is a schematic diagram of the welding part structure of the present invention.

[0041] Wherein: 1, welding power source; 2, positive power supply line; 3, test water tank; 4, welding torch; 5, clamping mechanism; 6, waterproof housing; 7, laser head; 8, laser beam; 9, ultrasonic transducer; 10, optical fiber; 11, ultrasonic power supply; 12, gas supply mechanism; 13, laser generator; 14, welded workpiece; 15, ultrasonic horn; 16, bubble; 17, copper tube; 18, flux-cored wire; 19, contact tip; 20, conducting rod; 21, arc; 22, droplet; 23, fixture; 24, negative power supply line. Detailed Embodiment

[0042] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and gives detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0043] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the welding part structure of the present invention, as Figure 1 and Figure 2As shown in the figure, an ultrasonic-assisted underwater laser-FCAW hybrid wet welding device includes a laser-FCAW hybrid welding device composed of a laser welding mechanism and a flux-cored wire arc welding mechanism, and an ultrasonic assistance mechanism. The laser welding mechanism and the ultrasonic assistance mechanism are coaxially arranged. During the welding process, the ultrasonic radiation force generated by the ultrasonic assistance mechanism acts on the bubbles 16 on the surface of the welding workpiece 14, delaying the floating time of the bubbles 16, reducing the floating frequency of the bubbles 16, and at the same time weakening the repulsive effect of the buoyancy of the bubbles 16 on the droplet 22 transition, thereby improving the quality of the welded joint.

[0044] Preferably, the laser welding mechanism and the flux-cored wire arc welding mechanism are respectively arranged at both ends of the traveling mechanism through the clamping mechanism 5; the laser welding mechanism includes a laser head 7.

[0045] The ultrasonic assistance mechanism includes a waterproof housing 6 fixed to the front end of the laser head 7, an ultrasonic transducer 9 and an ultrasonic horn 15 fixedly arranged inside the waterproof housing 6 from top to bottom in sequence, and a copper tube 17 sequentially passing through the axial inner hole of the ultrasonic transducer 9 and the axial inner hole of the ultrasonic horn 15. The copper tube 17 is coaxially arranged with the laser head 7 and perpendicularly arranged with respect to the welding workpiece 14. In this embodiment, the ultrasonic horn 15 is threadedly connected to the ultrasonic transducer 9; one end of the copper tube 17 communicates with one end of a ventilation pipe connected to the waterproof housing 6, and the other end of the ventilation pipe communicates with the gas supply mechanism 12.

[0046] Preferably, the rear end of the copper tube 17 is flush with the rear end of the ultrasonic transducer 9, and an inflation chamber is formed among the rear end of the copper tube 17, the rear end of the ultrasonic transducer 9 and the waterproof housing 6. The inflation chamber communicates with the ventilation pipe.

[0047] Preferably, the ultrasonic transducer 9 is electrically connected to the ultrasonic power supply 11; the laser head 7 is connected to the laser generator 13 through an optical fiber 10; the flux-cored wire arc welding mechanism is electrically connected to the positive electrode of the welding power supply 1, and the negative electrode of the welding power supply 1 is electrically connected to the welding workpiece 14. In this embodiment, the positive electrode of the welding power supply 1 is connected to the flux-cored wire arc welding mechanism through a positive power line 2 and connected to the welding workpiece 14 through a negative power line 24.

[0048] Preferably, the flux-cored wire arc welding mechanism includes a welding torch 4, a conducting rod 20 and a conducting nozzle 19 sequentially connected to the clamping mechanism 5. In this embodiment, the conducting nozzle 19 and the conducting rod 20 are threadedly connected, and the flux-cored wire 18 passes through the welding torch 4 and the conducting rod 20 in sequence and then passes out through the conducting nozzle 19.

[0049] The angle between the central axis of the contact tip 19 and the welding workpiece 14 is 30°-60°, and the vertical distance between the contact tip 19 and the welding workpiece 14 is between 10 mm and 20 mm; the horizontal distance between the front end of the contact tip 19 and the front end of the copper tube 17 is between 5 mm and 10 mm. Preferably, the vertical distance between the laser head 7 and the welding workpiece 14 is between 300 mm and 500 mm; the vertical distance between the front end of the ultrasonic horn 15 and the welding workpiece 14 is between 30 mm and 150 mm. It should be noted that the front end described in this embodiment refers to the end close to the welding workpiece 14, and the rear end refers to the end far from the welding workpiece 14.

[0050] Preferably, the welding parameters of the ultrasonic assisting mechanism are: ultrasonic frequency: 20 kHz - 30 kHz, ultrasonic power: 100 W - 400 W, ultrasonic amplitude: 3 μm - 50 μm. Preferably, the welding parameters of the laser welding mechanism are: laser energy: 1.5 kW - 3 kW. Preferably, the welding parameters of the flux-cored wire 18 mechanism are: welding voltage: 25 V - 40 V, welding current: 150 A - 250 A.

[0051] The ultrasonic-assisted underwater laser-FCAW hybrid wet welding method includes the following steps:

[0052] Step 1: Installation and debugging

[0053] Step 1.1: Installation

[0054] Respectively set the laser welding mechanism and the flux-cored wire 18 arc 21 welding mechanism with the ultrasonic assisting mechanism on the clamping mechanisms 5 at both ends of the traveling mechanism;

[0055] Step 1.2: Debugging

[0056] Adjust the relative distance and angle between the laser welding mechanism and the flux-cored wire arc welding mechanism, as well as their distances and angles relative to the welding workpiece 14 through the clamping mechanism 5 and the traveling mechanism, until the angle between the central axis of the contact tip 19 and the welding workpiece 14 is 30°-60°, the vertical distance between the contact tip 19 and the welding workpiece 14 is between 10 mm and 20 mm; the horizontal distance between the contact tip 19 and the copper tube 17 is between 5 mm and 10 mm; the vertical distance between the laser head 7 and the welding workpiece 14 is between 300 mm and 500 mm; the vertical distance between the front end of the ultrasonic horn 15 and the welding workpiece 14 is between 30 mm and 150 mm;

[0057] Step 2: Start the traveling mechanism, control the overall running speed at 2.5 - 8 m / min, simulate a traveling trajectory once, and after confirming smooth running without obstacles, reset;

[0058] Step 3: Turn on the ultrasonic power supply 11. After the ultrasonic-assisted mechanism works stably, turn on the air supply mechanism 12 to supply air into the waterproof housing 6 until the water in the copper tube 17 is drained completely;

[0059] Step 4: Input the welding parameters;

[0060] Step 5: Start the welding power supply 1 and the laser generator 13 in sequence. The flux-cored wire 18 of the flux-cored wire arc welding mechanism contacts the welding workpiece 14 to form a circuit, generating an arc. The laser generator transmits the laser to the laser head 7 through the optical fiber, and the laser is radiated to the welding workpiece by means of the laser head 7. At the same time, wet welding is carried out under the assistance of the ultrasonic-assisted mechanism;

[0061] Step 6: After welding is completed, turn off the traveling mechanism, the laser generator 13, the welding power supply 1, the ultrasonic power supply 11 and the air supply mechanism 12 in sequence.

[0062] For further illustration, the following test examples are disclosed:

[0063] This test example takes a 316L steel plate with a thickness of 10 mm as an example to illustrate the test processing steps:

[0064] Step 1: Fix the welding specimen to the bottom of the test water tank 3 through the fixture 23. Then, inject water into the test water tank 3 so that the welding workpiece 14 is below the water surface. Adjust the relative distance and angle between the clamping mechanism 5, the traveling mechanism, the laser welding mechanism and the flux-cored wire arc welding mechanism, as well as the distance and angle between the two relative to the welding workpiece 14, so that the distance between the laser head 7 and the welding workpiece 14 is between 300 mm and 500 mm, the distance between the front end of the ultrasonic horn 15 and the welding workpiece 14 is between 30 mm and 150 mm, the distance between the front end of the contact tip 19 and the welding workpiece 14 is between 10 mm and 20 mm, and the distance between the front end of the contact tip 19 and the front end of the copper tube 17 is between 5 mm and 10 mm;

[0065] Step 2: Start the traveling mechanism, control the overall running speed at 2.5 - 8 m / min, simulate a walking trajectory once. After confirming that the operation is stable and there is no obstacle, reset;

[0066] Step 3: Turn on the ultrasonic power supply 11 and adjust the ultrasonic parameters. Ultrasonic frequency: 20 kHz - 30 kHz, ultrasonic power: 100 W - 400 W, ultrasonic amplitude: 3 μm - 50 μm;

[0067] Step 4: After the ultrasonic-assisted mechanism works stably, turn on the air supply mechanism 12 to supply air into the waterproof housing 6;

[0068] Step 5: After the water in the copper tube 17 is drained, input the welding parameters of the laser welding mechanism: laser energy: 1.5 kW - 3 kW; at the same time, input the welding parameters of the flux cored arc welding mechanism: welding voltage: 25 V - 40 V, welding current: 150 A - 250 A.

[0069] Step 6: Start the welding power supply 1 and the laser generator 13 in sequence. The flux cored wire 18 of the flux cored arc welding mechanism contacts the welding workpiece 14 to form a circuit, generating an arc. The laser generator transmits the laser to the laser head 7 through the optical fiber, and the laser beam 8 is radiated onto the welding workpiece by means of the laser head 7 for underwater laser - FCAW composite wet welding.

[0070] Step 7: After welding is completed, turn off the traveling mechanism, the laser generator 13, the welding power supply 1, the ultrasonic power supply 11 and the gas supply mechanism 12 in sequence, and the welding ends.

[0071] Finally, it should be noted that another patent applied by the same applicant on the same day utilizes the laser - flux cored arc welding (FCAW) composite welding technology, which takes advantage of the characteristics of both the laser and the arc 21, giving full play to the advantages of the heat sources of the laser and the arc 21, and has the advantages of large penetration depth, strong bridging ability, high welding speed, low heat input, and small welding deformation, etc., solving the problem of unstable droplet 22 transfer in existing wet welding. The principle of underwater laser - FCAW composite welding is as follows: First, the laser directly acts on the arc 21, attracting and compressing the arc 21, reducing the electromagnetic force that hinders the droplet 22 transfer, promoting the droplet 22 transfer, increasing the transfer frequency, and thus improving the welding stability; Second, the gas - forming agent and water in the flux cored wire 18 continuously undergo thermal decomposition, evaporation or reaction to form bubbles 16, providing a gas environment for the arc 21 and laser welding. However, during the underwater welding process, the bubbles 16 are periodically formed, grow, float and burst, still disturbing the welding arc 21 and the droplet 22 transfer, and thus affecting the stability of the welding process and the quality of the welded joint.

[0072] In response to this, the present embodiment is further improved.

[0073] Therefore, how to solve the instability of the arc 21, bubbles 16 and droplet 22 transfer, and improve the stability of the underwater laser - FCAW composite wet welding process and the quality of the welded joint is a problem that has always troubled those skilled in the art, and at the same time is the key to the long - term development and wide application of the underwater laser - FCAW composite wet welding technology.

[0074] Therefore, with the above structure adopted in the present invention, during the welding process, the ultrasonic radiation force generated by ultrasonic vibration acts on the bubbles 16 on the welding workpiece 14, delaying the floating time of the bubbles 16, providing a stable gas environment for laser-FCAW hybrid welding, reducing the absorption of laser energy by water, and improving the utilization rate of laser energy. At the same time, the ultrasonic action reduces the floating frequency of the bubbles 16, weakens the disturbance effect of the bubbles 16, resulting in a reduced degree of fluctuation of the arc 21, thereby improving the stability of the arc 21. Moreover, the repulsive effect of the buoyancy of the bubbles 16 on the droplet 22 transfer is weakened, enabling the droplet 22 to transfer in a stable manner, which is beneficial to improving the stability of the welding process. In addition, the acoustic streaming effect generated by ultrasonic vibration can make the water around the welding workpiece 14 form a stable beam flow, effectively reducing the influence of the water flow disturbance at the welding workpiece 14 on the welding quality. Therefore, the present invention can effectively improve the stability of the laser-FCAW hybrid underwater wet welding process and achieve the purpose of improving the quality of underwater wet welding joints.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An ultrasonic-assisted underwater laser-FCAW hybrid wet welding device, characterized in that: It includes a laser-FCAW composite welding device composed of a laser welding mechanism and a flux-cored wire arc welding mechanism, and an ultrasonic assisting mechanism. The laser welding mechanism is coaxially arranged with the ultrasonic assisting mechanism, and is used to, during the welding process, utilize the ultrasonic radiation force generated by the ultrasonic assisting mechanism to act on the bubbles on the surface of the welded workpiece, delay the floating time of the bubbles, reduce the floating frequency of the bubbles, and at the same time weaken the repulsive effect of the buoyancy of the bubbles on the droplet transfer, thereby improving the quality of the welded joint; The laser welding mechanism and the flux-cored wire arc welding mechanism are respectively arranged at both ends of the traveling mechanism through the clamping mechanism; the laser welding mechanism includes a laser head; The ultrasonic assisting mechanism includes a waterproof housing fixed at the front end of the laser head, an ultrasonic transducer and an ultrasonic horn fixedly arranged inside the waterproof housing from top to bottom in sequence, and a copper tube sequentially penetrating through the axial inner hole of the ultrasonic transducer and the axial inner hole of the ultrasonic horn. The copper tube is coaxially arranged with the laser head and is perpendicularly arranged with respect to the welded workpiece; One end of the copper tube communicates with one end of a ventilation pipe connected to the waterproof housing, and the other end of the ventilation pipe communicates with a gas supply mechanism; The flux-cored wire arc welding mechanism includes a welding torch, a conductive rod and a conductive nozzle sequentially connected to the clamping mechanism, and the flux-cored wire sequentially passes through the welding torch and the conductive rod and then exits from the conductive nozzle; The angle between the central axis of the conductive nozzle and the welded workpiece is 30° - 60°, and the vertical distance between the conductive nozzle and the welded workpiece is between 10 mm and 20 mm; The horizontal distance between the front end of the conductive nozzle and the front end of the copper tube is between 5 mm and 10 mm; The vertical distance between the laser head and the welded workpiece is between 300 mm and 500 mm; The vertical distance between the front end of the ultrasonic horn and the welded workpiece is between 30 mm and 150 mm.

2. The ultrasonic-assisted underwater laser-FCAW hybrid wet welding device according to claim 1, wherein: The rear end of the copper tube is flush with the rear end of the ultrasonic transducer, and an air inflation chamber is formed among the rear end of the copper tube, the rear end of the ultrasonic transducer and the waterproof housing. The air inflation chamber communicates with the ventilation pipe; 3. The ultrasonic-assisted underwater laser-FCAW hybrid wet welding device according to claim 1, wherein: The ultrasonic transducer is electrically connected to an ultrasonic power supply; The laser head is connected to a laser generator through an optical fiber; The flux-cored wire arc welding mechanism is electrically connected to the positive pole of a welding power supply, and the negative pole of the welding power supply is electrically connected to the welded workpiece.

4. The ultrasonic-assisted underwater laser-FCAW hybrid wet welding device according to claim 1, characterized in that: The welding parameters of the ultrasonic assisting mechanism are: ultrasonic frequency: 15 kHz - 30 kHz, ultrasonic power: 100 W - 400 W, ultrasonic amplitude: 3 μm - 50 μm.

5. The ultrasonic-assisted underwater laser-FCAW hybrid wet welding device according to claim 1, wherein: The welding parameters of the laser welding mechanism are: laser energy: 1.5 kW - 10 kW.

6. The ultrasonic-assisted underwater laser-FCAW hybrid wet welding device according to claim 1, characterized in that: The welding parameters of the flux-cored wire arc welding mechanism are: welding voltage: 25 V - 40 V, welding current: 150 A - 250 A.

7. An ultrasonic-assisted underwater laser-FCAW hybrid wet welding method, which uses the ultrasonic-assisted underwater laser-FCAW hybrid wet welding device as described in claim 3 above, is characterized in that: It includes the following steps: Step 1: Installation and debugging Step 1.1: Installation The flux-cored wire arc welding mechanism and the laser welding mechanism with the ultrasonic assisting mechanism are respectively arranged on the clamping mechanisms at both ends of the traveling mechanism; Step 1.2: Debugging Adjust the relative distance and angle between the laser welding mechanism and the flux-cored wire arc welding mechanism, as well as their distances and angles relative to the welding workpiece through the clamping mechanism and the traveling mechanism until the angle between the central axis of the contact tip and the welding workpiece is 30°-60°, the vertical distance between the contact tip and the welding workpiece is between 10 mm and 20 mm; the horizontal distance between the contact tip and the copper tube is between 5 mm and 10 mm; the vertical distance between the laser head and the welding workpiece is between 300 mm and 500 mm; the vertical distance between the front end of the ultrasonic horn and the welding workpiece is between 30 mm and 150 mm; Step 2: Start the traveling mechanism, control the overall running speed at 2.5 m / min - 8 m / min, simulate a traveling trajectory, and after confirming smooth running without obstacles, reset; Step 3: Turn on the ultrasonic power supply, and after the ultrasonic auxiliary mechanism works stably, turn on the gas supply mechanism to supply gas into the waterproof housing until the water in the copper tube is drained; Step 4: Input the welding parameters; Step 5: Start the welding power supply and the laser generator in sequence. The flux-cored wire of the flux-cored wire arc welding mechanism contacts the welding workpiece to form a circuit, generating an arc. The laser generator transmits the laser to the laser head through the optical fiber, and the laser is radiated to the welding workpiece by means of the laser head. At the same time, wet welding is carried out under the assistance of the ultrasonic auxiliary mechanism; Step 6: After welding is completed, turn off the traveling mechanism, the laser generator, the welding power supply, the ultrasonic power supply and the gas supply mechanism in sequence.

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