Underwater double-path ultrasonic synergistic laser-electric arc hybrid welding repair device and method

Abstract

The invention belongs to the technical field of underwater welding, and discloses an underwater double-path ultrasonic synergistic laser-electric arc hybrid welding repair device and method. The device comprises a two-way ultrasonic synergistic TIG welding gun and a laser head which are both fixed on an external drainage cover, and sealing penetration pieces are arranged on the external drainage cover for the two-way ultrasonic synergistic TIG welding gun and the laser head; the double-path ultrasonic synergistic TIG welding gun comprises a tungsten electrode sound path and an end part sound path; the tungsten electrode sound path transmits ultrasonic energy to a welding gun tungsten electrode through a tungsten electrode ultrasonic transducer, the electric field at the root of the welding gun tungsten electrode and the micro-motion behavior of the welding gun tungsten electrode are affected, and therefore the electric arc is compressed, and the position of the root of the electric arc is finely adjusted. The end sound path acts on the end of the welding gun through the end ultrasonic transducers in an annular array, directional sound radiation pressure is applied, an electric arc column and the surface of a molten pool are adjusted, heat input is promoted to be evenly distributed, and the symmetry of the molten pool is improved. The welding quality and the process stability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of underwater welding technology, and particularly relates to an underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device and method. Background Technology

[0002] The localized drainage hood contains a relatively strong protective airflow. This airflow flows around the arc column, superimposed with the flow fields of laser vapor plume and argon arc welding shielding gas, causing random loads on the arc root, resulting in transient offsets and bends. This leads to surface undulations in the molten pool and unstable droplet transition, increasing spatter. In laser-arc hybrid welding, the laser forms deep penetration in the center of the weld, while the arc, attracted by the laser, is more likely to burn in the center, leading to overheating in the center, insufficient heat input on the weld sidewalls, and incomplete fusion. In fillet welds, this results in defects such as incomplete penetration / burn-through at the inner corner and collapse at the outer corner. To control the arc, preventing irregular vibrations and excessive heat input due to continuous burning in the weld center, the arc shape and oscillation direction must be controlled to keep the arc in a manageable state.

[0003] Currently, the main methods for controlling electric arcs are as follows: 1. Mechanical oscillation, which relies on the oscillation of the gun body to distribute heat flow, but it has a large inertia, slow response (tens to hundreds of milliseconds), and a fixed oscillation trajectory, making it difficult to perform real-time vector countermeasures against disturbances; 2. Single-channel coaxial ultrasound, although it can increase the directivity of the electric arc, has poor directionality / insufficient degrees of freedom, making it difficult to simultaneously achieve directional offset and controllable rotation, and has limited effect on suppressing electric arc disturbances under strong disturbance conditions.

[0004] Current methods for controlling the shape and deflection direction of electric arcs mainly include magnetic control, mechanical control, and ultrasonic control.

[0005] Using magnetic control to oscillate plasma, such as the invention patent for a rotating arc sensor with magnetic focusing arc function (publication number CN106891074B, publication date 20191018), provides a magnetically controlled rotating arc sensor that uses a magnetic field to control the deflection of the arc and can also converge the arc while it is deflecting. This is used to solve the current drawbacks such as unstable arc divergence, large arc transition angle, and lack of arc heat concentration.

[0006] A mechanical structure is used to rotate the electric arc, such as the invention patent for a rotating arc narrow gap welding torch (publication number CN100531993C, publication date 20090826), which provides a rotating arc welding torch for narrow gaps. The motor drives the conductive rod and conductive nozzle to rotate eccentrically around the central axis of the welding torch through an eccentric sleeve, and the welding wire is fed out from the center of the conductive nozzle to realize the welding process.

[0007] Using ultrasound to shrink the arc and improve its straightness, such as the invention patent of a welding method combining ultrasound and non-consumable electrode arc (publication number CN100577340C, publication date: 20080716), discloses that under non-consumable electrode gas shielded welding conditions, ultrasound is transmitted to the welding arc through a conductive electrode. After applying ultrasound, the arc produces a significant shrinkage phenomenon, which improves the straightness of the arc and thus enhances the arc's ability to resist disturbances.

[0008] Based on the above analysis, the existing technologies have the following problems and defects: Using magnetron control to oscillate the plasma results in a magnetron-controlled arc that is sensitive to welding current and lacks sufficient thrust in the low-current range; narrow bevels and ferromagnetic workpieces cause magnetic circuit distortion and easy distortion of the deflection direction; implementation requires multiple coils and complex power supplies, leading to large size, heat generation, and sealing difficulties, especially in underwater local dry processes. Furthermore, strong magnetic fields easily cause electromagnetic interference to the laser / sensor, and primarily promote arc propulsion while failing to simultaneously improve molten pool degassing. In contrast, ultrasonic control is decoupled from current, is not limited by magnetic circuits or materials, and allows for small transducers that are easily coaxially integrated; through amplitude / phase coordination of the "tungsten electrode acoustic path + coaxial end-face acoustic path," programmable directional offset and small-radius rotation can be achieved in milliseconds, precisely distributing heat; simultaneously, acoustic flow enhances wetting, aiding in degassing and porosity reduction, breaking columnar crystals, improving sidewall fusion and forming symmetry; and the absence of electromagnetic interference makes its advantages even more significant in space-constrained and highly disturbed scenarios such as laser-arc composite processes, narrow gaps, and underwater local dry processes.

[0009] Rotating the electric arc using a mechanical structure typically relies on the oscillation of the welding torch to distribute heat flow, but this method has significant drawbacks. First, the large inertia results in a slow response time, usually on the order of tens to hundreds of milliseconds, far below the rapid reaction time required for welding. Second, the fixed oscillation trajectory cannot be quickly adjusted according to the direction of real-time disturbances, making it difficult to effectively counteract external disturbances. This fixed trajectory leads to a relatively simple heat distribution pattern, making it impossible to finely control the heat according to the specific needs of the welding process. Furthermore, the oscillation system often experiences significant mechanical wear during operation, affecting the long-term stability and reliability of the system, especially in complex welding environments (such as underwater partial dry welding), where sealing and protecting mechanical components is difficult, thus increasing maintenance costs.

[0010] While single-channel coaxial ultrasound can increase the directivity of the electric arc, directing it towards the target position through the directional effect of sound pressure, it suffers from limitations in directionality and degrees of freedom. Specifically, single-channel ultrasound can only apply force in one direction, making it difficult to simultaneously achieve directional deflection and controllable rotation. This limits its application in complex welding environments, especially under conditions of strong underwater disturbance. Because there is only a single sound pressure source, the effective range of the ultrasound is limited, resulting in a very limited effect on suppressing arc disturbances. When strong shielding gas flows in the environment, single-channel ultrasound struggles to cancel out disturbances, thus making it difficult to maintain stability and consistency during the welding process. Summary of the Invention

[0011] To overcome the problems existing in related technologies, the present invention discloses an underwater dual-channel ultrasonic coordinated laser-arc composite welding repair device and method, specifically relating to an underwater local dry dual-channel ultrasonic coordinated laser-arc composite welding repair device and method.

[0012] The technical solution is as follows: An underwater dual-channel ultrasonic coordinated laser-arc composite welding repair device, including a dual-channel ultrasonic coordinated TIG welding torch and a laser head, wherein the dual-channel ultrasonic coordinated TIG welding torch and the laser head are both fixed on an external drainage cover, and a sealing penetrating part is provided on the external drainage cover for the dual-channel ultrasonic coordinated TIG welding torch and the laser head. The dual-path ultrasonic co-current TIG welding torch includes a tungsten electrode acoustic path and an end acoustic path; The tungsten electrode acoustic path transmits ultrasonic energy to the tungsten electrode of the welding torch through the tungsten electrode ultrasonic transducer, affecting the electric field at the root of the tungsten electrode and the micro-motion behavior of the tungsten electrode, thereby compressing the arc and fine-tuning the position of the arc root. The end acoustic path acts on the end of the welding torch through the end ultrasonic transducers of the ring array, applying directional acoustic radiation pressure to adjust the arc column and the surface of the molten pool, promoting uniform heat input distribution and improving the symmetry of the molten pool.

[0013] Furthermore, the tungsten electrode acoustic path includes a welding torch tungsten electrode, the rear end of which is sequentially fixed to the inner middle of the tungsten electrode ultrasonic connector, the tungsten electrode ultrasonic transducer, and the tungsten electrode ultrasonic fixing component, and at least one set of symmetrically arranged tungsten electrode fixing blocks are installed in the middle of the welding torch tungsten electrode from front to back. The tungsten electrode ultrasonic fixing component is fixed to the rear end of the tungsten electrode ultrasonic transducer, and the tungsten electrode ultrasonic connector is fixed to the front end of the tungsten electrode ultrasonic transducer.

[0014] Furthermore, the end acoustic path includes an end ultrasonic fixing component, and a portion of the tungsten electrode ultrasonic transducer and the tungsten electrode ultrasonic connector are both fixed in the middle of the end ultrasonic fixing component; the end ultrasonic transducer is fixed at the front end of the end ultrasonic fixing component; an end ultrasonic amplitude transformer is fixedly connected to the front of the end ultrasonic transducer; and an argon arc welding gun insulating sleeve is installed through the middle of both the end ultrasonic transducer and the end ultrasonic amplitude transformer.

[0015] Furthermore, the tungsten electrode fixing block is a rubber component, which blocks the transmission of ultrasonic vibration of the tungsten electrode and the insulating sleeve of the argon arc welding gun. The connection between the insulating sleeve of the argon arc welding gun and the end ultrasonic fixing component is made of rubber and insulated with sealant on the outside. The welding torch tungsten electrode serves as the TIG cathode, with an ultrasonic amplitude transformer extending from its front end. The insulating sleeve of the argon arc welding gun is made of ceramic or polymer insulation. The tungsten electrode ultrasonic connector is an ultrasonic amplitude transformer made of titanium alloy, which efficiently couples the ultrasonic energy generated by the tungsten electrode ultrasonic transducer to the tungsten electrode. The tungsten electrode ultrasonic transducer is a piezoelectric / magnetostrictive transducer, which is connected to the tungsten electrode ultrasonic fixing component to form the tungsten electrode acoustic path. The tungsten electrode ultrasonic fixing component is placed outside the external drainage cover and is connected to the tungsten electrode ultrasonic transducer through a sealed connection, providing frequency / amplitude / phase adjustable drive. The end ultrasonic transducers are arranged in a ring sector array at the outer end of the insulating sleeve. Each sector is driven independently or in pairs to achieve directional sound pressure and acoustic flow in different directions, forming the end acoustic path.

[0016] Furthermore, the end ultrasonic amplitude transformer includes a first ultrasonic head, a second ultrasonic head, a third ultrasonic head, a fourth ultrasonic head, a fifth ultrasonic head, a sixth ultrasonic head, a seventh ultrasonic head, and an eighth ultrasonic head arranged in a circular pattern.

[0017] Another objective of this invention is to provide an underwater dual-channel ultrasonic-assisted laser-arc hybrid welding repair method, which implements the aforementioned underwater dual-channel ultrasonic-assisted laser-arc hybrid welding repair device, and the method includes: Step 1, Pre-welding preparation: Install the external drainage cover onto the moving device and bring it into contact with the workpiece surface to complete the cavity drainage and gas filling circulation; Position the laser head and the dual-channel ultrasonic collaborative TIG welding torch at the predetermined angle and relative distance, so that the laser optical axis is basically aligned with the weld centerline and the front end of the welding torch points to the area to be welded; Check the tungsten electrode extension and end face morphology of the welding torch, confirm the mechanical pre-tightening, acoustic coupling and electrical insulation status of the tungsten electrode ultrasonic connector and the tungsten electrode ultrasonic transducer, and confirm the acoustic vibration isolation and water seal of the potting layer of the tungsten electrode fixing block and the tungsten electrode ultrasonic transducer and the insulating sleeve; Connect the tungsten electrode ultrasonic fixing component to the tungsten electrode ultrasonic power supply and the end array drive of the end ultrasonic transducer, complete the no-load frequency response and phase calibration, and calibrate the laser power, focal length / depth of focus, protective gas flow rate and exhaust path; Step 2, Normal Welding without Ultrasonic: Under the condition of maintaining a stable and dry space inside the drainage hood and constant laser head parameters, first turn off both ultrasonic channels, and use only laser + TIG for short-range arc initiation and uniform wire / gun feeding to obtain stable process window and baseline data under ultrasonic-free conditions, including the corresponding relationship between laser power, welding speed, arc voltage, penetration depth and cross-sectional geometry, porosity and spatter statistics. Step 3: Dual-channel ultrasonic phase-coordinated welding; Step 4, Post-weld: After completing the set welding process, first gradually reduce the amplitude and shut down the tungsten electrode acoustic path and the end acoustic path; then maintain TIG and shielding gas for a short time to achieve crater backfilling and slow cooling, then turn off the arc and laser in sequence, restore the cavity to normal pressure and lift the drain cover; finally, check the welding torch tungsten electrode, tungsten electrode fixing block, potting and the ultrasonic annular sector array of the end ultrasonic transducer.

[0018] Step 3, dual-path ultrasonic phase-coordinated welding, includes: while maintaining the laser's stable penetration depth, the tungsten electrode acoustic path and the end acoustic path are introduced sequentially. First, the tungsten electrode ultrasonic transducer is turned on to verify the stable response at the arc root; then, the ultrasonic annular sector array of the end ultrasonic transducer at the welding torch tip is activated, the target sector is selected, and the phase difference φ and amplitude ratio A2 / A1 with the tungsten electrode acoustic path are set. When φ is constant, constant-direction fixed-point offset is achieved, and the arc heat is directed towards the underheated sidewall or root. A small-radius pre-spin is generated by determining the rotation beat frequency to homogenize the circumferential heat flux density and dynamic pressure, and to enhance sidewall wetting and root backfilling; when the rotation beat frequency is set to 50-200Hz, a small-radius pre-spin is generated, and the radius r is 0.2-0.4 of the short axis of the molten pool. Dual-channel ultrasonic excitation forms a stable offset circular or elliptical trajectory during arc motion, used for directional energy replenishment and enhanced heating in the weld edge region. In terms of control strategy, the system employs proportional-integral-derivative (PID) closed-loop regulation, using real-time collected arc pressure fluctuations, arc root bright spot centroid deviation, and molten pool free surface undulations as feedback signals. After fusion processing, the system outputs arc position and disturbance intensity criteria, and accordingly fine-tunes the phase difference φ, offset radius r, and envelope frequency f of the dual-channel ultrasound to counteract arc offset caused by shielding gas flow disturbances and molten pool instability. Through this dynamic adjustment, the alignment of the arc center with the weld centerline is continuously maintained, ensuring full fusion between the weld sidewall and the centerline molten pool. Simultaneously, selective driving of different sectors in the end-effector ultrasonic transducer array enables rapid switching and vectorized control of the arc offset direction, improving welding stability and weld formation consistency under complex spatial postures.

[0019] Furthermore, in the process of generating control parameters based on preset arc offset direction, offset radius, rotation frequency or elliptical trajectory parameters, the amplitude sequence includes the opening sequence, output amplitude, excitation time window and excitation frequency for each array element of the end array. By superimposing sound pressure peaks in a predetermined direction, the fixed-point energy replenishment and heat input enhancement of the molten pool edge or weld toe area are achieved.

[0020] In the process of synthesizing and modulating the electric arc through dual acoustic paths, by periodically changing the initial value of the phase difference φ(t) and the modulation amount Δφ(t), the arc root is made to form a stable circular or elliptical trajectory relative to the weld centerline, thereby realizing programmable heat input distribution and fusion zone morphology control.

[0021] In the closed-loop feedback correction process, a hierarchical PID control strategy is adopted. The bright spot centroid offset is used as the main control variable to accurately correct the alignment error between the arc and the weld centerline. The arc pressure change and the undulation of the molten pool free surface are used as auxiliary control variables to suppress arc length fluctuations and molten pool transition metal instability, thereby achieving coordinated optimization control of arc trajectory, molten pool morphology and heat input uniformity. Combining all the above technical solutions, the beneficial effects of this invention are as follows: This invention employs an ultrasonic actuation path on both the tungsten electrode and the coaxial end face (TIG welding torch nozzle end face): the tungsten electrode acoustic path couples ultrasonic vibrations along the electrode axis to the arc root and plasma column, achieving efficient transmission of additional load / micro-displacement at the arc root; the coaxial end face acoustic path forms a controllable acoustic radiation pressure around the arc column and above the molten pool surface, applying directional pressure to the plasma and free surface. Simultaneously, another ultrasonic path is applied to the coaxial end face. The two ultrasonic paths are decoupled and controlled in terms of amplitude A1 and A2, frequency f1 and f2, and phase φ1 and φ2: using dual-path phase / amplitude, arbitrary planar vectors can be generated to offset and rotate the arc, precisely counteracting any disturbance.

[0022] The ultrasonic control of this invention achieves programmable directional offset and small-radius rotation through acoustic coupling and current decoupling, free from the limitations of mechanical inertia and welding trajectory. It can respond to disturbance changes in milliseconds and achieve programmable directional offset and small-radius rotation through precise coordinated control of phase and amplitude. It can perform fine dynamic distribution of heat flow during welding, while avoiding the inertial lag and wear problems caused by mechanical oscillation, and has higher control accuracy and response speed.

[0023] This invention utilizes a dual-channel ultrasonic coordinated approach to apply force simultaneously in different directions, enabling programmable directional offset and small-radius rotation. This significantly enhances the precise control of the electric arc, especially under conditions of strong disturbance, effectively suppressing random arc drift and morphological instability, thereby significantly improving welding quality and process stability.

[0024] This invention develops a compact device capable of adapting to high underwater airflow disturbances. It employs a composite heat source to improve welding repair efficiency and introduces ultrasonic energy to reduce defects generated during welding repair. This device can improve welding quality and efficiency, producing high-quality welds. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure; Figure 1 This is a schematic diagram of the underwater dual-channel ultrasonic coordinated laser-arc composite welding repair device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the connection of each component of the dual-channel ultrasonic collaborative TIG welding torch provided in an embodiment of the present invention; Figure 3 This is a top view of the dual-channel ultrasonic co-current TIG welding torch provided in an embodiment of the present invention; Figure 4 This is a diagram showing the internal structure of each component of the dual-channel ultrasonic co-current TIG welding torch provided in this embodiment of the invention; Figure 5 This is a schematic diagram of the components of the end ultrasonic amplitude transformer provided in an embodiment of the present invention; In the diagram: 1. Dual-channel ultrasonic co-working TIG welding torch; 1-1. Tungsten electrode of the welding torch; 1-2. Tungsten electrode fixing block; 1-3. Insulating sleeve of the argon arc welding torch; 1-4. Tungsten electrode ultrasonic connector; 1-5. Tungsten electrode ultrasonic transducer; 1-6. Tungsten electrode ultrasonic fixing component; 1-7. End ultrasonic fixing component; 1-8. End ultrasonic transducer; 1-9. End ultrasonic amplitude transformer; 1-9-1. First ultrasonic head; 1-9-2. Second ultrasonic head; 1-9-3. Third ultrasonic head; 1-9-4. Fourth ultrasonic head; 1-9-5. Fifth ultrasonic head; 1-9-6. Sixth ultrasonic head; 1-9-7. Seventh ultrasonic head; 1-9-8. Eighth ultrasonic head; 2. Laser head; 3. External drainage cover. Detailed Implementation

[0026] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] This invention proposes a dual-path ultrasonic synergistic control arc technology based on a tungsten electrode acoustic path and an end array acoustic path. By programmably controlling the phase difference, amplitude sequence, and array element selection of the two ultrasonic paths, customizable heat input distribution such as two-dimensional offset, rotation, and elliptical trajectory of the arc can be achieved within the weld cross-section. Combined with closed-loop control using arc pressure, arc root bright spot centroid, and molten pool free surface undulation as feedback quantities, real-time automatic correction and disturbance rejection stability of the arc position can be achieved. At the same time, acoustic flow is used to enhance the internal flow of the molten pool, promote bubble degassing and microstructure refinement, thereby achieving synergistic optimization in terms of arc stability, molten pool dynamics, and weld formation and mechanical properties.

[0028] Example 1, Technical terms related to the present invention: Local dry underwater welding (LDUW): This method involves creating a localized dry air chamber on the surface of the workpiece underwater using an external drainage hood, thereby enabling welding / repair in a "dry" environment.

[0029] Laser-Arc Hybrid Welding (LAHW): A composite welding method in which two heat sources, a laser and an electric arc, work together coaxially or nearly coaxially to achieve deep penetration and filling / forming.

[0030] Dual-channel ultrasound: The two ultrasound channels of this invention are the tungsten electrode acoustic path and the end acoustic path, which work together to control the deflection and rotation of the electric arc.

[0031] Acoustic Radiation Pressure: The equivalent steady-state pressure generated by ultrasound in a medium, which exerts a considerable directional additional load on an arc column / free surface.

[0032] Vector Bias: By synthesizing the phase and amplitude of two ultrasonic waves, a lateral "thrust" with a fixed direction is generated, causing the arc center to deflect towards the target side.

[0033] Phase and phase difference (φ): refer to the relative phase relationship between two ultrasonic excitations; the phase difference determines the direction of displacement and whether rotation occurs.

[0034] Proportional-Integral-Derivative (PID) control: an error-based closed-loop control algorithm used to fine-tune phase, radius, and cycle time.

[0035] like Figures 1-5As shown in the figure, the underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device provided in this embodiment of the invention includes: a dual-channel ultrasonic-assisted TIG welding torch 1, an external drainage cover 3, and a laser head 2. The dual-channel ultrasonic-assisted TIG welding torch 1 has the following structure: Figures 2-4 As shown, the dual-channel ultrasonic co-processing TIG welding torch 1 includes a welding torch tungsten electrode 1-1, a tungsten electrode fixing block 1-2, an argon arc welding torch insulating sleeve 1-3, a tungsten electrode ultrasonic connector 1-4, a tungsten electrode ultrasonic transducer 1-5, a tungsten electrode ultrasonic fixing component 1-6, and an end ultrasonic welding torch with an end ultrasonic amplitude transformer 1-9, an end ultrasonic transducer 1-8, and an end ultrasonic fixing component 1-7.

[0036] The dual-channel ultrasonic co-working TIG welding torch 1 and laser head 2 are both fixed on the external drainage cover 3. The drainage cover 3 is provided with a sealing through-piece for the dual-channel ultrasonic co-working TIG welding torch 1 and laser head 2 to ensure coaxiality and sealing.

[0037] The rear end of the welding torch tungsten electrode 1-1 is sequentially fixed to the inner middle of the tungsten electrode ultrasonic connector 1-4, the tungsten electrode ultrasonic transducer 1-5, and the tungsten electrode ultrasonic fixing component 1-6. At least one set of symmetrically arranged tungsten electrode fixing blocks 1-2 are installed in the middle of the welding torch tungsten electrode 1-1 from front to back. The front end of the welding torch tungsten electrode 1-1 extends out of the center of the end ultrasonic amplitude transformer 1-9. The tungsten electrode ultrasonic fixing component 1-6 is fixed to the rear end of the tungsten electrode ultrasonic transducer 1-5, and the tungsten electrode ultrasonic connector 1-4 is fixed to the front end of the tungsten electrode ultrasonic transducer 1-5. A portion of the tungsten electrode ultrasonic transducer 1-5 and the tungsten electrode ultrasonic connector 1-4 are both fixed to the middle of the end ultrasonic fixing component 1-7. The end ultrasonic transducer 1-8 is fixed to the front end of the end ultrasonic fixing component 1-7. The end ultrasonic amplitude transformer 1-9 is fixedly connected to the front of the end ultrasonic transducer 1-8. The argon arc welding gun insulating sleeve 1-3 is installed through the middle of the end ultrasonic transducer 1-8 and the end ultrasonic amplitude transformer 1-9. The tungsten electrode 1-1 of the welding torch and at least one symmetrically arranged tungsten electrode fixing blocks 1-2 are both housed inside the insulating sleeve 1-3 of the argon arc welding torch. The tungsten electrode fixing block 1-2 is a rubber component that blocks the transmission of ultrasonic vibrations from the tungsten electrode and the insulating sleeve 1-3 of the argon arc welding gun. The connection between the insulating sleeve 1-3 of the argon arc welding gun and the end ultrasonic fixing component 1-7 is also made of rubber and insulated with sealant on the outside, thus blocking the propagation of ultrasonic waves along the welding gun body and achieving acoustic vibration isolation and electrical insulation.

[0038] For example, the end ultrasonic transducers 1-8 are located outside the insulating sleeve 1-3 of the argon arc welding gun and are a ring array that supports independent or paired driving (phase / amplitude controllable). The dual-channel ultrasound achieves directional displacement and small-radius rotation of the arc column through phase difference and amplitude; at the same time, the end array can selectively activate a certain sector to change the displacement direction.

[0039] like Figure 1 As shown, the external drainage cover 3 is an integral part of a localized dry cavity, forming a controllable localized dry cavity against the workpiece surface to simulate a land-based working environment; it includes an adjustable support for mounting the laser head 2 and the TIG welding torch 1, and is equipped with a sealing through-piece for cables, gas, and cooling channels. Its functions are: to isolate external water pressure and flow, to provide a protective atmosphere, and to provide a dry environment.

[0040] like Figure 1 As shown, the laser head 2 is fixed on the external drainage cover 3, with its optical axis basically aligned with the weld centerline to provide stable penetration depth. The focal length and incident angle are adjustable, and it maintains a fixed relative position with the dual-channel ultrasonic co-current TIG welding torch 1, as shown. Figure 2 As shown; when combined with TIG, the laser is responsible for "stabilizing the melting depth", while the electric arc is "directionally replenished with energy" under the action of dual-channel ultrasound.

[0041] like Figure 4 As shown, in the dual-path ultrasonic co-guided TIG welding torch 1, the tungsten electrode 1-1 of the welding torch serves as the TIG cathode, with its front end extending appropriately; it also acts as an acoustic conductor in the tungsten electrode acoustic path, delivering the ultrasound directly to the arc root. The tungsten electrode fixing block 1-2, a rubber elastomer, provides mechanical support and acoustic vibration isolation between the tungsten electrode and the welding torch body, blocking the propagation of ultrasound along the torch body and providing electrical insulation and a water seal.

[0042] The insulating sleeves 1-3 of the argon arc welding gun are made of ceramic or polymer insulation. The outer end is connected to the "end acoustic path" with potting to ensure insulation, sealing and vibration isolation.

[0043] The tungsten electrode ultrasonic connector 1-4 is an ultrasonic amplitude transformer made of titanium alloy, which efficiently couples the ultrasonic energy generated by the tungsten electrode ultrasonic transducer 1-5 to the tungsten electrode 1-1. The tungsten electrode ultrasonic transducer 1-5 is a piezoelectric / magnetostrictive transducer, which is connected to the tungsten electrode ultrasonic fixing component 1-6 to form the tungsten electrode acoustic path. The tungsten electrode ultrasonic fixing component 1-6 is placed outside the external drainage cover 3 (e.g., Figure 1 The ultrasonic transducer 1-5 is connected to the tungsten electrode ultrasonic transducer 1-5 through a sealed connection, providing frequency / amplitude / phase adjustable drive. The end ultrasonic transducers 1-8 are arranged in an annular sector array (preferably 8 sectors, but not limited to 8) at the outer end of the insulating sleeve 1-3. Each sector can be driven independently or in pairs to achieve directional sound pressure and acoustic flow in different directions, forming the end acoustic path.

[0044] like Figure 3 The end ultrasonic fixing components 1-7 are arranged in an annular sector array at the outer end of the insulating sleeve 1-3, preferably 8 sectors, but not limited to 8, and correspond to the annular sector array of the end ultrasonic transducers 1-8. like Figure 5The end ultrasonic amplitude transformer 1-9 includes a first ultrasonic head 1-9-1, a second ultrasonic head 1-9-2, a third ultrasonic head 1-9-3, a fourth ultrasonic head 1-9-4, a fifth ultrasonic head 1-9-5, a sixth ultrasonic head 1-9-6, a seventh ultrasonic head 1-9-7, and an eighth ultrasonic head 1-9-8 arranged in a circle.

[0045] Example 2: The working principle of this invention relies on the acoustic excitation system of the dual-channel ultrasonic co-current TIG welding torch 1. By using ultrasound to precisely control the arc and molten pool, it solves the problems of arc instability, uneven heat input distribution, and frequent defects in traditional underwater local dry welding processes. Specifically, the acoustic excitation system of the dual-channel ultrasonic co-current TIG welding torch 1 optimizes and controls the arc morphology by precisely adjusting the excitation mode of the ultrasound.

[0046] The acoustic excitation system of the dual-channel ultrasonic co-current TIG welding torch 1 consists of two ultrasonic channels: a tungsten electrode acoustic path and an end acoustic path.

[0047] The tungsten electrode acoustic path transmits ultrasonic energy to the welding torch tungsten electrode 1-1 through the tungsten electrode ultrasonic transducer 1-5, affecting the electric field at the root of the welding torch tungsten electrode 1-1 and the micro-motion behavior of the welding torch tungsten electrode 1-1, thereby compressing the arc, fine-tuning the position of the arc root, increasing the arc's sensitivity to disturbances, and thus improving arc stability.

[0048] The end acoustic path acts on the end of the welding torch through the end ultrasonic transducers 1-8 of the ring array, applying directional acoustic radiation pressure to finely adjust the arc column and the surface of the molten pool, promoting uniform heat input distribution and improving the symmetry of the molten pool.

[0049] The acoustic excitation system of this ultrasonic-assisted TIG welding torch achieves programmable control of the arc shape by precisely programming and adjusting the excitation mode of the ultrasonic waves, including the adjustment of phase, amplitude, and frequency.

[0050] The end-stage ultrasonic amplitude transformer 1-9 (end-stage ultrasonic system) in the end-stage acoustic path includes multiple independently controlled ultrasonic heads, including: first ultrasonic head 1-9-1, second ultrasonic head 1-9-2, third ultrasonic head 1-9-3, fourth ultrasonic head 1-9-4, fifth ultrasonic head 1-9-5, sixth ultrasonic head 1-9-6, seventh ultrasonic head 1-9-7, and eighth ultrasonic head 1-9-8, typically eight ultrasonic transducer units. These ultrasonic heads work together to act on the arc column and the molten pool surface through phase and amplitude adjustment. The excitation mode of each ultrasonic head can be driven individually or in pairs to achieve acoustic radiation pressure and acoustic flow in different directions.

[0051] 1. Amplitude sequence control and directional rotation modulation based on the end acoustic path; When a constant phase difference is maintained between the tungsten electrode acoustic path and the end acoustic path in the ultrasonic device at a certain working position, selective activation of the end ultrasonic heads at different positions can achieve superposition and enhancement of ultrasonic wave peaks in a specific direction, increasing the ultrasonic energy in that direction. This, in turn, applies greater directional sound pressure to the arc, causing the arc to deflect in the specified direction. The eight ultrasonic heads in the end acoustic path can generate ultrasonic excitations of different amplitudes in different directions and at different times. When the eight ultrasonic heads operate sequentially according to a predetermined order and amplitude combination, programmed deflection of the arc can be achieved. For example, at time t0, if only ultrasonic head 1 operates with an amplitude of 10 μm, the arc will deflect in the opposite direction to ultrasonic head 1; at time t1, if ultrasonic head 3 is activated and excited with an amplitude of 15 μm, the arc will deflect in the opposite direction to ultrasonic head 3, and the deflection amplitude will be greater. When each ultrasonic head is periodically activated in a preset sequence, the electric arc will produce continuous and regular deflection, thus forming a rotational trajectory. Combined with differential amplitude control, an elliptical rotational trajectory can be further formed, achieving better heat input distribution and promoting homogenization of the molten pool flow. Furthermore, by adjusting the amplitude of each ultrasonic head in the end acoustic path in real time, the intensity of ultrasonic excitation can be precisely controlled, thereby adjusting the arc offset to keep the arc at the desired position and avoid over- or under-offset. Moreover, by adjusting the activation frequency of each ultrasonic head, the arc rotation speed can be effectively controlled, thereby adjusting its rotational trajectory and achieving stable and precise control of the arc and molten pool morphology.

[0052] 2. Dual-path cooperative directional control based on phase difference modulation; Another method for adjusting the electric arc is phase control. The tungsten electrode acoustic path and the end acoustic path simultaneously influence the arc's shape. The tungsten electrode acoustic path (tungsten ultrasonic) directly transmits ultrasonic excitation to the arc via the tungsten electrode 1-1 of the welding torch, improving the arc's response sensitivity to the end ultrasonic waves and providing a basis for subsequent directional control. The end acoustic path utilizes two paired ultrasonic heads (e.g., ultrasonic heads 1 and 5). By adjusting the relative phase of these two ultrasonic heads, the ultrasonic waves are superimposed or canceled in a certain direction, thereby controlling the arc's directional deviation within the same plane. This improves the lateral distribution of heat input during welding, preventing localized overheating at the center of the weld pool or excessively rapid cooling at the edges. During welding, by adjusting the ultrasonic phase difference between the tungsten electrode acoustic path and the end acoustic path in real time, the system can dynamically correct the arc position, maintaining it on an ideal trajectory, thus improving weld formation stability and weld pool stress balance.

[0053] The two ultrasonic control modes can operate independently or work in conjunction. By precisely adjusting the amplitude and phase of the dual-channel ultrasound, the arc can move stably along a preset elliptical trajectory during welding, thereby achieving a more uniform heat input distribution. Especially at the weld edges, it effectively avoids overheating or insufficient cooling. The system precisely adjusts the phase difference and amplitude ratio to ensure the arc moves stably along the predetermined trajectory during welding, preventing deviation from the welding centerline and improving weld quality.

[0054] To achieve acoustic vibration isolation and electrical insulation of the tungsten electrode acoustic path and the end acoustic path (tungsten electrode ultrasound and end ultrasound), this invention designs a tungsten electrode fixing block 1-2 and an argon arc welding torch insulating sleeve 1-3. The elastic properties of the tungsten electrode fixing block 1-2 effectively block the propagation of ultrasonic waves along the welding torch body, ensuring that the ultrasonic waves are accurately transmitted to the tungsten electrode 1-1 region of the welding torch. At the same time, the tungsten electrode fixing block 1-2 has good electrical insulation properties, preventing the arc or welding current from propagating through the welding torch body, thereby avoiding electrical short circuits. The argon arc welding torch insulating sleeve 1-3 is located between the welding torch body and the end ultrasonic transducer 1-8. In addition to providing electrical isolation, it also effectively plays a role in acoustic vibration isolation, ensuring that the energy of the end ultrasound does not affect the welding torch body.

[0055] Through the above design, the acoustic excitation system of the ultrasonic-assisted TIG welding torch of the present invention improves arc stability, optimizes the heat input distribution during the welding process, reduces the generation of defects, improves welding quality, and can effectively control the arc shape and molten pool flow, thereby making the welding process more precise and stable.

[0056] Example: Description of process parameters.

[0057] The frequency of the ultrasonic welding torch's tungsten electrode 1-1 is typically set between 20kHz and 40kHz to ensure effective transmission of ultrasonic waves to the root of the arc while avoiding interference with the welding current. The amplitude is generally controlled within the range of 1-10μm, and the phase adjustment, together with the phase difference of the end acoustic path, determines the arc's offset direction or rotation mode. When the phase difference is constant, the arc will deviate in a directional manner.

[0058] The end-stage acoustic path applies directional acoustic radiation pressure to the arc column and molten pool surface through end-stage ultrasonic transducers 1-8, forming a precise heat input distribution. Its frequency is typically set in the range of 20kHz to 40kHz, consistent with the ultrasound from the tungsten electrode 1-1 of the welding torch, ensuring accurate energy transfer. The amplitude of the end-stage ultrasound is controlled between 10-20μm; by adjusting the amplitude, the force applied to the molten pool and arc column can be changed, achieving adjustment of both. The phase adjustment of the end-stage acoustic path (end-stage ultrasound) works in conjunction with the phase difference of the tungsten electrode acoustic path to control the directional shift and minute rotation of the arc, thereby optimizing the heat input distribution and avoiding overheating or insufficient cooling in the middle (e.g., 1. amplitude sequence control and directional rotation modulation based on the end-stage acoustic path; 2. dual-path coordinated directional control based on phase difference modulation).

[0059] Example 3, the underwater dual-channel ultrasonic-assisted laser-arc composite welding repair method provided in this embodiment of the invention includes: Step 1, Pre-welding preparation: Install the external drainage cover 3 onto the moving device and ensure good contact with the workpiece surface to complete the cavity drainage and gas filling cycle; Position the laser head 2 and the dual-channel ultrasonic collaborative TIG welding torch 1 at the predetermined angle and relative distance, so that the laser optical axis is basically aligned with the weld centerline and the front end of the welding torch points to the area to be welded; Check the extension and end face morphology of the tungsten electrode 1-1 of the welding torch, and confirm the mechanical pre-tightening, acoustic coupling and electrical insulation status of the tungsten electrode ultrasonic connector 1-4 and the tungsten electrode ultrasonic transducer 1-5. The potting layer of the tungsten electrode fixing block 1-2 and the ultrasonic and insulating sleeve 1-3 at the end of the welding torch should be complete and free of cracks to ensure acoustic vibration isolation and water sealing; Connect the tungsten electrode ultrasonic fixing component 1-6 to the tungsten electrode ultrasonic power supply and the end array drive of the end ultrasonic transducer 1-8, complete the no-load frequency response and phase calibration (select the resonance point in the 20-40kHz carrier frequency range), and calibrate the laser power, focal length / depth of focus, protective gas flow rate and exhaust path.

[0060] Step 2, Normal Welding Without Ultrasonics: Under the condition of maintaining a stable and dry space inside the drainage hood 3 and constant parameters of the laser head 2, first turn off both ultrasonic circuits, and use only laser + TIG for short-range arc ignition and uniform wire / gun feed to obtain stable process window and baseline data under ultrasonic-free conditions, including the corresponding relationship between laser power, welding speed, arc voltage, penetration depth and cross-sectional geometry, porosity and spatter statistics, etc.; This stage is used to verify the stable maintenance capability of the centerline laser for keyholes and deep penetration, as well as the natural drift characteristics of the TIG arc in the underwater local dry environment, to provide a reference for the gain evaluation after subsequent ultrasonic superposition. At the same time, the focal position, shielding gas ratio and nozzle-workpiece distance are corrected according to the actual situation to avoid misjudging non-ultrasonic factors as process improvement or abnormality after ultrasonic intervention.

[0061] Step 3, Dual-path ultrasonic phase-coordinated welding: While maintaining "laser-controlled penetration depth", the tungsten electrode acoustic path and the end acoustic path are introduced sequentially: First, the tungsten electrode ultrasonic transducers 1-5 are turned on with a small amplitude to verify the stable response of the arc root; then, the ultrasonic annular sector array of the end ultrasonic transducers 1-8 at the end of the welding torch is activated, the target sector is selected and the phase difference φ and amplitude ratio A2 / A1 with the tungsten electrode acoustic path are set. When φ is constant, constant directional fixed-point offset is achieved, and the arc heat is directionally deflected towards the underheated sidewall or root (e.g., 1. amplitude sequence control and directional rotation adjustment based on the end acoustic path, 2. dual-path coordinated directional control based on phase difference adjustment).

[0062] When the rotation frequency is set to 50-200Hz, a small radius pre-rotation is generated. The radius r is preferably 0.2-0.4 of the short axis of the molten pool, which is used to homogenize the circumferential heat flux density and dynamic pressure and enhance the wetting of the sidewalls and the backfilling of the root. Superimposing a constant offset phase yields an "offset circle / ellipse" trajectory, used for targeted energy replenishment at the weld edge. The entire process employs a proportional-integral-derivative control closed loop, using arc pressure, arc root bright spot centroid deviation, and free surface undulations as feedback to fine-tune φ, r, and envelope frequency online. This maintains alignment between the arc center and weld centerline, and ensures full fusion of the sidewall and centerline molten pool even during shielding gas flow disturbances. In actual welding, the system first acquires the arc pressure waveform, the centroid coordinates of the arc root bright spot, and the characteristic curves of the molten pool's free surface undulations in real time via a high-speed sampling module. These physical quantities serve as feedback signals characterizing arc offset and molten pool disturbance states. Transient fluctuations in arc pressure are used to determine arc length and stability, the offset of the arc root bright spot centroid reflects the actual position of the arc in the plane, and the amplitude and phase difference of the free surface undulations characterize the intensity of shielding gas flow disturbances and the non-uniformity of flow within the molten pool. Specifically, when the arc deflects towards the protective gas flow side, causing the center of gravity of the arc root bright spot to shift, the system increases the amplitude of the ultrasonic head in the opposite direction and adjusts the phase of adjacent ultrasonic heads to enhance the synthetic sound pressure vector in the opposite direction of the shift, thereby achieving rapid arc return to center. When the free surface undulation of the molten pool increases, indicating that the flow field is more disturbed, the system appropriately increases the envelope frequency f to increase the rotation speed, accelerates the redistribution of heat input, and promotes symmetrical flow of the molten pool. In the case of insufficient fusion of the weld sidewall, the system increases the offset radius r to increase the residence time of the arc in the trajectory edge region, thereby enhancing sidewall heating and achieving full fusion.

[0063] Step 4, Post-weld: After completing the set welding process, first gradually reduce the amplitude and shut down the two ultrasonic channels to avoid transient rebound. Then, maintain TIG and shielding gas for a short time to achieve crater backfilling and slow cooling. Subsequently, turn off the arc and laser in sequence, restore the cavity to normal pressure, and lift the drainage cover 3. Perform appearance and cross-sectional metallographic evaluation on the weld. Finally, perform routine inspection and necessary replacement of the ultrasonic annular sector array of the welding torch tungsten electrode 1-1, tungsten electrode fixing block 1-2, potting and end ultrasonic transducer 1-8 to ensure acoustic coupling, insulation and sealing reliability for the next use.

[0064] Application example.

[0065] like Figure 5 As shown, the end ultrasonic amplitude transformer 1-9 (end ultrasonic system) consists of eight independent ultrasonic heads, including: first ultrasonic head 1-9-1, second ultrasonic head 1-9-2, third ultrasonic head 1-9-3, fourth ultrasonic head 1-9-4, fifth ultrasonic head 1-9-5, sixth ultrasonic head 1-9-6, seventh ultrasonic head 1-9-7, and eighth ultrasonic head 1-9-8. Together with the central tungsten electrode acoustic path (tungsten electrode ultrasound), they form a dual-channel ultrasonic structure.

[0066] For example, when it is necessary to shift the arc towards the direction of the first ultrasonic head 1-9-1, the fifth ultrasonic head 1-9-5 can be turned on, and the frequency of the fifth ultrasonic head 1-9-5 can be made to match the frequency of the tungsten electrode acoustic path (tungsten electrode ultrasound), but there is a phase difference between the two.

[0067] Under this configuration, the end acoustic path (end ultrasound) generates sound pressure, pushing the arc to deflect in the direction of the first ultrasonic head 1-9-1. At the same time, due to the phase difference between the tungsten electrode acoustic path (tungsten electrode ultrasound) and the end acoustic path (end ultrasound), the ultrasonic waves generated by the two interact, enhancing the peak value of the ultrasonic waves in a predetermined direction, further promoting the arc to deflect in that direction.

[0068] When it is necessary to rotate the electric arc, this can be achieved by sequentially starting and stopping the ultrasonic heads. For example, by sequentially turning on the first ultrasonic head 1-9-1 to the eighth ultrasonic head 1-9-8, the electric arc will rotate clockwise. The frequency of rotation is determined by the speed at which the ultrasonic heads are turned on and off. By adjusting the working time and frequency of the ultrasonic heads, the speed and frequency of rotation can be precisely controlled.

[0069] If it is necessary to adjust the amplitude of the arc deflection, it can be controlled by adjusting the amplitude of the tungsten electrode acoustic path (tungsten electrode ultrasound) and the end acoustic path (end ultrasound). The larger the amplitude, the greater the arc deflection, and vice versa.

[0070] Through the above implementation steps, this technical solution can achieve stable drying and adjustment for underwater local dry welding repair, improving the precision, stability, and efficiency of the welding. This technical solution has high technical value and practicality, and can be widely applied in the field of underwater dry welding repair.

[0071] As can be seen from the above embodiments, the present invention proposes a device structure and acoustic coupling: a laser head and a dual-path ultrasonic co-working TIG welding gun 1 are integrated on an external drainage cover, wherein the first acoustic path is a tungsten electrode acoustic path (tungsten electrode ultrasonic transducer → amplitude transformer → tungsten electrode axial coupling), and the second acoustic path is an end acoustic path located on the outside of the insulating sleeve in a ring sector array, preferably 8 sectors, which can be driven independently or in pairs; acoustic vibration isolation, electrical insulation and water sealing are achieved through elastic rubber blocks and potting layers, so that ultrasonic energy is concentrated in the effective channels of "tungsten electrode - arc root" and "end - arc column / free surface".

[0072] This invention proposes a phase-amplitude-frequency coordinated arc vector control method: the two ultrasonic waves are decoupled and controllable in phase / amplitude / frequency; a constant phase difference can generate directional offset; superimposed offset phases can form offset circular / elliptical trajectories; and feedforward amplification and beat adjustment are implemented before the turning angle Δt=50–150ms; the preferred parameter range is: carrier frequency 20–40kHz, rotation beat 50–200Hz, offset radius r=0.2–0.4×molten pool minor axis; closed-loop fine adjustment can be selected with feedback from arc pressure, arc root bright spot centroid and free surface undulation.

[0073] The application scheme and effects of laser-arc functional decoupling in this invention are as follows: In underwater local dry laser-arc hybrid welding, the division of labor is established as "laser stabilizes penetration depth and arc provides directional energy supplementation": the laser provides centerline stability for keyhole and penetration depth, and dual-path ultrasonic waves vectorize and distribute arc heat to the sidewalls and promote gas detachment, achieving consistency in keyhole circumferential homogenization, sidewall wetting, and root backfilling; the corresponding protective technical effects include significant convergence of arc pressure fluctuations, improved penetration depth symmetry, and reduced porosity and burn-through defect rate, thereby widening the process window and improving the first-pass yield.

[0074] By combining the above innovations, the underwater partial dry welding repair device of this invention can achieve stable drying and real-time adjustment during the welding repair process, thereby improving the precision, stability, and efficiency of welding. This technical solution has high technical value and practicality, and can be widely applied in the field of underwater partial dry welding repair.

[0075] To address the imbalance often observed in laser-arc hybrid welding, where heat accumulates at the centerline while the weld periphery is underheated, this invention employs a "dual-path ultrasonic synergy" system. The tungsten electrode acoustic path directly reaches the arc root, while the end-mounted annular acoustic path acts on the arc column and free surface. Phase and amplitude coordination enables directional arc shifting and small-radius rotation. Simultaneously, the laser is confined to provide a stable centerline penetration depth, achieving functional decoupling between "laser-stabilized penetration depth" and "arc-directional energy replenishment." Consequently, heat input and sound pressure can be programmably redistributed, resulting in excellent wetting around the weld, significantly improved cross-sectional symmetry, and effective suppression of defects such as incomplete fusion and burn-through.

[0076] In underwater localized dry processing environments, protective airflow disturbances can cause random arc deflection and induce porosity. This invention utilizes an end-ring array of ultrasonic waves to generate directionally adjustable acoustic radiation pressure and acoustic flow, acting on the molten pool surface to promote gas detachment from the molten pool. Simultaneously, a tungsten electrode acoustic path applies micro-vibration and additional load to the arc root, improving the arc's resistance to external disturbances. The two acoustic fields are used to cancel out disturbances in opposite directions through phase selection proportional-integral-derivative control. The results show convergence of arc pressure fluctuations and arc root drift, more uniform stress on the molten pool surface, reduced metal spatter, and a significant decrease in porosity volume fraction and the number of macropores.

[0077] Compared to solutions relying on mechanical oscillation or magnetic coils, this invention generates a small-radius rotational trajectory on a millisecond scale using ultrasonic phase changes. It eliminates the need for large-inertia moving parts and bulky magnetic circuits, resulting in compact hardware that can be coaxially integrated with the welding torch / drainage cover, and avoids electromagnetic interference issues. Therefore, while ensuring equivalent forming quality, it can increase welding speed or reduce heat input per unit length, shorten cycle time, and reduce rework rates. Simultaneously, it maintains high accessibility and robustness in narrow spaces and complex curved surface conditions, significantly broadening the stable process window for laser-arc hybrid welding in underwater localized dry environments.

[0078] To further illustrate the effects of the embodiments of the present invention, the following experiments were conducted.

[0079] This invention, based on a dual-path ultrasonic collaborative control mechanism of tungsten electrode acoustic path and end acoustic path, achieves programmable control over arc behavior and molten pool flow. Its technical effects can be theoretically explained by three core mechanisms: arc dynamics, acoustohydrodynamics, and energy distribution control. First, by controlling the amplitude sequence of the end acoustic path, a spatiotemporally controllable acoustic pressure field can be constructed around the arc. When each ultrasonic head is sequentially excited according to the set amplitude combination and activation sequence, the acoustic pressure gradients generated in different directions form a periodic directional force on the outer periphery of the arc column, causing the arc column to shift or rotate within milliseconds. This directly applies pressure and shear force to the plasma, independent of current, and therefore not limited by electromagnetic stiffness. Compared to the inertia and hysteresis inherent in mechanical oscillation, the dual-path ultrasonic action possesses extremely short transmission paths and high-speed response characteristics, making the arc trajectory easier to control precisely, and the heat input distribution closer to the theoretically calculated ideal state.

[0080] Secondly, based on the principles of acoustic hydrodynamics, the high-frequency acoustic field generated by the end acoustic path can induce stable acoustic flow on the surface of the molten pool, forming forced convection along the radial and circumferential directions. This acoustic flow can significantly alter the fluid circulation pattern of the molten pool, resulting in a more uniform distribution of temperature and solute. The acoustic flow reduces the resistance encountered by bubbles migrating from the depths of the molten pool to the free surface, shortening their residence time and helping to reduce porosity, a common problem in underwater narrow-gap welding. Simultaneously, the enhanced convection also alters the shape of the solidification interface, thereby increasing the degree of interface disturbance, promoting grain refinement, and increasing the content of equiaxed grains, providing a theoretical basis for the uniformity of weld microstructure and mechanical properties.

[0081] Furthermore, from the perspective of plasma properties and electromagnetic-acoustic-fluid coupling, the tungsten electrode acoustic path directly couples ultrasound to the arc root region, allowing for continuous fine-tuning of the temperature field, conductivity distribution, and current density within the arc column under acoustic pressure modulation. The propagation of sound waves in the plasma leads to transient compression and expansion, causing periodic adjustments in the arc column's contraction, thereby enhancing its self-convergence capability. When shielding gas disturbances, molten pool free surface fluctuations, or thermal plume instabilities exist in the welding environment, the dual-path ultrasound provides additional stabilizing "restoring force" to the arc through the vector synthesis effect of amplitude and phase, enabling it to quickly return to the centerline position after disturbances occur. This significantly reduces arc pressure fluctuations and arc root drift, improving the overall robustness of the welding process.

[0082] Finally, in the dual-path coordinated control mode, amplitude sequence control provides macroscopic "trajectory planning," while phase difference control provides refined "direction correction." When combined, the arc can stably operate along a preset elliptical trajectory or an offset trajectory, achieving directional energy replenishment to the weld edge region while avoiding excessive heat input in the central region. Theoretically, this "programmable heat input" can achieve the optimal temperature field in different bevel shapes and different weld passes, thereby improving sidewall fusion quality, reducing the probability of incomplete penetration and poor fusion, and achieving a comprehensive improvement in forming symmetry, microstructure uniformity, and weld reliability.

[0083] In summary, the dual-path ultrasonic coupling control mechanism of this invention provides solid theoretical support for arc stability, molten pool dynamics, degassing behavior, and heat input controllability through multi-field coupling effects such as acoustic pressure, acoustic flow, and arc property reconstruction. This significantly improves welding quality and process adaptability, demonstrating the unique advantages of this invention in complex scenarios such as narrow gap welding, arc-laser hybrid welding, and underwater local dry welding.

[0084] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device, characterized in that, The device includes a dual-channel ultrasonic co-working TIG welding torch (1) and a laser head (2). The dual-channel ultrasonic co-working TIG welding torch (1) and the laser head (2) are both fixed on an external drainage cover (3). A sealing through-piece is provided on the external drainage cover (3) for the dual-channel ultrasonic co-working TIG welding torch (1) and the laser head (2). The dual-path ultrasonic co-operated TIG welding torch (1) includes a tungsten electrode acoustic path and an end acoustic path; The tungsten electrode acoustic path transmits ultrasonic energy to the welding torch tungsten electrode (1-1) through the tungsten electrode ultrasonic transducer (1-5), affecting the electric field at the root of the welding torch tungsten electrode (1-1) and the micro-movement behavior of the welding torch tungsten electrode (1-1), thereby compressing the arc and fine-tuning the position of the arc root. The end acoustic path acts on the end of the welding torch through the end ultrasonic transducers (1-8) of the ring array, applying directional acoustic radiation pressure to adjust the arc column and the surface of the molten pool, promoting uniform heat input distribution and improving the symmetry of the molten pool.

2. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device according to claim 1, characterized in that, The tungsten electrode acoustic path includes a welding torch tungsten electrode (1-1). The rear end of the welding torch tungsten electrode (1-1) is sequentially fixed to the inner middle of the tungsten electrode ultrasonic connector (1-4), the tungsten electrode ultrasonic transducer (1-5), and the tungsten electrode ultrasonic fixing component (1-6). At least one set of symmetrically arranged tungsten electrode fixing blocks (1-2) are installed in the middle of the welding torch tungsten electrode (1-1) from front to back. The tungsten electrode ultrasonic fixing component (1-6) is fixed at the rear end of the tungsten electrode ultrasonic transducer (1-5), and the tungsten electrode ultrasonic connector (1-4) is fixed at the front end of the tungsten electrode ultrasonic transducer (1-5).

3. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device according to claim 2, characterized in that, The end acoustic path includes an end ultrasonic fixing component (1-7), a portion of the tungsten electrode ultrasonic transducer (1-5) and the tungsten electrode ultrasonic connector (1-4) are both fixed in the middle of the end ultrasonic fixing component (1-7); an end ultrasonic transducer (1-8) is fixed at the front end of the end ultrasonic fixing component (1-7); an end ultrasonic amplitude transformer (1-9) is fixedly connected to the front of the end ultrasonic transducer (1-8); an argon arc welding gun insulating sleeve (1-3) is installed through the middle of both the end ultrasonic transducer (1-8) and the end ultrasonic amplitude transformer (1-9).

4. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device according to claim 3, characterized in that, The tungsten electrode fixing block (1-2) is a rubber part that blocks the transmission of ultrasonic vibration of the tungsten electrode and the insulating sleeve (1-3) of the argon arc welding gun. The connection between the insulating sleeve (1-3) of the argon arc welding gun and the end ultrasonic fixing part (1-7) is made of rubber and insulated with sealant on the outside. The welding torch tungsten electrode (1-1) serves as the TIG cathode, with the front end extending out to the end ultrasonic amplitude transformer (1-9). The insulating sleeve (1-3) of the argon arc welding gun is made of ceramic or polymer insulation. The tungsten electrode ultrasonic connector (1-4) is an ultrasonic amplitude transformer made of titanium alloy, which efficiently couples the ultrasonic energy generated by the tungsten electrode ultrasonic transducer (1-5) to the tungsten electrode (1-1); the tungsten electrode ultrasonic transducer (1-5) is a piezoelectric / magnetostrictive transducer, which is connected to the tungsten electrode ultrasonic fixing component (1-6) to form a tungsten electrode acoustic path; the tungsten electrode ultrasonic fixing component (1-6) is placed outside the external drainage cover (3) and is connected to the tungsten electrode ultrasonic transducer (1-5) through a sealed connection, providing frequency / amplitude / phase adjustable drive; the end ultrasonic transducer (1-8) is arranged in an annular sector array at the outer end of the insulating sleeve (1-3), and each sector is driven independently or in pairs to realize directional sound pressure and acoustic flow in different directions, forming an end acoustic path.

5. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device according to claim 4, characterized in that, The end ultrasonic amplitude transformer (1-9) includes a first ultrasonic head (1-9-1), a second ultrasonic head (1-9-2), a third ultrasonic head (1-9-3), a fourth ultrasonic head (1-9-4), a fifth ultrasonic head (1-9-5), a sixth ultrasonic head (1-9-6), a seventh ultrasonic head (1-9-7), and an eighth ultrasonic head (1-9-8) arranged in a circle.

6. A method for underwater dual-channel ultrasonic-assisted laser-arc hybrid welding repair, characterized in that, This method implements the underwater dual-channel ultrasonic-assisted laser-arc composite welding repair device as described in any one of claims 1-5, and the method includes: Step 1, Pre-welding preparation: Install the external drainage cover (3) onto the moving device and make it contact the workpiece surface to complete the cavity drainage and gas filling cycle; Position the laser head (2) and the dual-path ultrasonic collaborative TIG welding gun (1) at the predetermined angle and relative distance, so that the laser optical axis is basically aligned with the weld centerline and the front end of the welding gun points to the area to be welded; Check the extension amount and end face morphology of the welding gun tungsten electrode (1-1), confirm the mechanical pre-tightening, acoustic coupling and electrical insulation status of the tungsten electrode ultrasonic connector (1-4) and the tungsten electrode ultrasonic transducer (1-5), and confirm the acoustic vibration isolation and water seal of the potting layer of the tungsten electrode fixing block (1-2) and the tungsten electrode ultrasonic transducer (1-5) and the insulating sleeve (1-3); Connect the tungsten electrode ultrasonic fixing piece (1-6) to the end array drive of the tungsten electrode ultrasonic power supply and the end ultrasonic transducer (1-8), complete the no-load frequency response and phase calibration, and calibrate the laser power, focal length / depth of focus, protective gas flow rate and exhaust path; Step 2, Normal welding without ultrasound: Under the condition of maintaining a stable and dry space inside the drainage cover (3) and constant parameters of the laser head (2), first turn off the two ultrasounds, and only use laser + TIG to perform short-range arc initiation and uniform wire / gun feeding to obtain stable process window and baseline data under ultrasound-free conditions, including the corresponding relationship between laser power, welding speed, arc voltage, penetration depth and cross-sectional geometry, porosity and spatter statistics. Step 3: Dual-channel ultrasonic phase-coordinated welding; Step 4, Post-weld: After completing the set welding process, first gradually reduce the amplitude and shut down the tungsten electrode acoustic path and the end acoustic path; then maintain TIG and shielding gas for a short time to achieve crater backfilling and slow cooling, then turn off the arc and laser in sequence, restore the cavity normal pressure and lift the drain cover (3); finally, check the ultrasonic annular sector array of the welding torch tungsten electrode (1-1), tungsten electrode fixing block (1-2), potting and end ultrasonic transducer (1-8).

7. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair method according to claim 6, characterized in that, Step 3, dual-path ultrasonic phase-coordinated welding, includes: while maintaining the laser's stable penetration depth, the tungsten electrode acoustic path and the end acoustic path are introduced sequentially. First, the tungsten electrode ultrasonic transducer (1-5) is turned on to verify the stable response of the arc root; then, the ultrasonic annular sector array of the end ultrasonic transducer (1-8) at the end of the welding torch is activated, the target sector is selected, and the phase difference φ and amplitude ratio A2 / A1 with the tungsten electrode acoustic path are set. When φ is constant, constant-direction fixed-point offset is achieved, and the arc heat is directed towards the underheated sidewall or root. A small-radius pre-rotation is generated by determining the rotation beat frequency to homogenize the circumferential heat flux density and dynamic pressure, and to enhance sidewall wetting and root backfilling; when the rotation beat frequency is set to 50-200Hz, a small-radius pre-rotation is generated, with the radius r being 0.2-0.4 of the short axis of the molten pool; Dual-channel ultrasonic excitation forms a stable offset circular or elliptical trajectory during arc motion, used for directional energy replenishment and enhanced heating in the weld edge region. In terms of control strategy, the system employs proportional-integral-derivative (PID) closed-loop regulation, using real-time collected arc pressure fluctuations, arc root bright spot centroid deviation, and molten pool free surface undulations as feedback signals. After fusion processing, the system outputs arc position and disturbance intensity criteria, and accordingly fine-tunes the phase difference φ, offset radius r, and envelope frequency f of the dual-channel ultrasound to counteract arc offset caused by shielding gas flow disturbances and molten pool instability. Through this dynamic adjustment, the alignment of the arc center with the weld centerline is continuously maintained, ensuring full fusion between the weld sidewall and the centerline molten pool. Simultaneously, selective driving of different sectors in the end-effector ultrasonic transducer (1-8) array enables rapid switching and vectorized control of the arc offset direction, improving welding stability and weld formation consistency under complex spatial postures.

8. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair method according to claim 7, characterized in that, In the process of generating control parameters based on preset arc offset direction, offset radius, rotation frequency or elliptical trajectory parameters, the amplitude sequence includes the opening sequence, output amplitude, excitation time window and excitation frequency for each array element of the end array. By superimposing sound pressure peaks in a predetermined direction, the fixed-point energy replenishment and heat input enhancement of the molten pool edge or weld toe area are achieved.

9. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair method according to claim 8, characterized in that, In the process of synthesizing and modulating the electric arc through dual acoustic paths, by periodically changing the initial value of the phase difference φ(t) and the modulation amount Δφ(t), the arc root is made to form a stable circular or elliptical trajectory relative to the weld centerline, thereby realizing programmable heat input distribution and fusion zone morphology control.

10. The underwater dual-channel ultrasonic-assisted laser-arc composite welding repair method according to claim 7, characterized in that, In the closed-loop feedback correction process, a hierarchical PID control strategy is adopted. The bright spot centroid offset is used as the main control variable to accurately correct the alignment error between the arc and the weld centerline. The arc pressure change and the free surface undulation of the molten pool are used as auxiliary control variables to suppress the arc length fluctuation and the instability of the molten pool transition metal, thereby achieving coordinated optimization control of arc trajectory, molten pool morphology and heat input uniformity.

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