Laser micro-arc complex coaxial welding device and method based on same-frequency modulation

Abstract

The invention discloses a laser micro-arc complex coaxial welding device and method based on co-frequency modulation, and belongs to the field of laser welding, and the device comprises an optical fiber laser heat source system which is used for generating an optical fiber laser beam to act on a welding wire to assist arcing and welding of a weldment; the semiconductor laser heat source system is used for increasing the metal melting amount of the large-gap to-be-welded joint; the pulse micro-arc welder is used for generating pulse micro-arc to be matched with the optical fiber laser beam for same-frequency adjustment; the control system is used for controlling each system; the pulse micro-arc welding machine is arranged in the laser-micro-arc coaxial welding head; a structured light measuring instrument and a visual scanner are arranged on the laser-micro-arc coaxial welding head and used for recognizing the gap size of a weldment. Through co-frequency modulation of the laser beam and the micro-arc, periodic development of optical fiber laser beam auxiliary arc droplet transfer and laser welding is achieved, and the problems that a large-gap welding joint cannot be welded, and the welding performance is poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a laser micro-arc composite coaxial welding device and method based on same-frequency modulation. Background Art

[0002] Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. Laser welding is to radiate a high-intensity laser beam onto the metal surface, and through the interaction between the laser and the metal, the metal is melted to form a welded joint. After the laser beam is focused by the optical system, its energy density is extremely high, and it can instantly heat the metal to the melting point or even vaporize it, thereby achieving welding.

[0003] Large gap laser welding refers to the process in which the gap of the weld is large, usually exceeding the range that can be tolerated by traditional welding methods. Large gap laser welding has the following difficulties: Welding is difficult: Due to the larger gap, higher energy density is required to melt and connect the materials, making welding more difficult; High welding quality requirements: Large gap welding needs to ensure the strength and sealing of the weld, and the welding quality requirements must meet the product use requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a laser micro-arc composite coaxial welding device and method based on co-frequency modulation. Through the co-frequency modulation of the laser beam and the micro-arc, the fiber laser beam assisted arc droplet transition and laser welding are carried out periodically, thereby solving the problem of the inability to weld and poor welding performance of large gap welding joints.

[0005] To achieve the above object, the present invention provides a laser micro-arc composite coaxial welding device based on co-frequency modulation, comprising: Fiber laser heat source system, used to generate fiber laser beam, part of the energy of fiber laser beam acts on welding wire to assist arc starting, and the other part of the energy acts on weldment to achieve deep penetration welding of metal; A semiconductor laser heat source system is used to generate a semiconductor laser beam to act on the weldment to increase the melting amount of the base metal of the weldment joint to be welded; Pulse micro-arc welding machine is used to generate pulse micro-arc and cooperate with the fiber laser beam to adjust the same frequency to achieve arc starting and stable melting of welding wire; The control system is connected with the fiber laser heat source system, semiconductor laser heat source system, and pulse micro-arc welding machine through signal lines, and controls each system; Laser-micro-arc coaxial welding head, the pulse micro-arc welding machine is arranged inside the laser-micro-arc coaxial welding head, and the laser-micro-arc coaxial welding head is provided with a structured light measuring instrument and a visual scanner for identifying the gap size of the weldment.

[0006] Preferably, the fiber laser heat source system includes a fiber laser connected to the laser-micro-arc coaxial welding head, and a fiber laser one-to-four beam splitter, a reflector one, and a co-frequency modulated reflector arranged inside the laser-micro-arc coaxial welding head. The fiber laser is connected to the fiber laser one-to-four beam splitter through a transmission fiber one, and the reflector one and the co-frequency modulated reflector are arranged below the fiber laser one-to-four beam splitter. The fiber laser beam generated by the fiber laser is split by a fiber laser one-to-four beam splitter, and then is focused on the end of the welding wire through a reflector one and a frequency-modulated reflector in sequence. The split fiber laser beam includes a fiber laser beam one, a fiber laser beam two, a fiber laser beam three, and a fiber laser beam four.

[0007] Preferably, the semiconductor laser heat source system includes a semiconductor laser connected to the laser-micro-arc coaxial welding head, and a semiconductor laser one-to-four beam splitter, a second reflector, and a third reflector arranged inside the laser-micro-arc coaxial welding head. The semiconductor laser is connected to the semiconductor laser one-to-four beam splitter through a second transmission optical fiber, and the second reflector and the third reflector are arranged below the semiconductor laser one-to-four beam splitter. The semiconductor laser beam generated by the semiconductor laser is split by a semiconductor laser one-to-four beam splitter, and then acts on the surface of the weldment through reflector two and reflector three in sequence. The split semiconductor laser beam includes semiconductor laser beam one, semiconductor laser beam two, semiconductor laser beam three, and semiconductor laser beam four.

[0008] Preferably, a welding wire output device for conveying welding wire is provided inside the pulse micro-arc welding machine, and the welding wire output device includes a welding wire reel, and a rotating shaft is provided at the center of the welding wire reel, and the rotating shaft is connected to the output shaft of the welding wire conveying motor. The pulse micro-arc welding machine is connected to a shielding gas cylinder through a conveying pipe, and the shielding gas cylinder is filled with shielding gas. A pulse micro-arc welding gun is provided at the bottom end of the pulse micro-arc welding machine.

[0009] Preferably, the same-frequency modulated reflector is arranged on a mirror base, and a rotating shaft rotatably connected to the inner wall of the laser-micro-arc coaxial welding head is arranged on the mirror base.

[0010] Preferably, there are four reflectors and four frequency modulated reflectors, which are evenly arranged around the pulse micro-arc welding machine; taking the first reflector one or the frequency modulated reflector as the reference, the subsequent three reflectors one or the frequency modulated reflectors are rotated 90 degrees in sequence.

[0011] Preferably, four reflectors 2 and 3 are provided and are evenly arranged around the pulse micro-arc welding machine; taking the first reflector 2 or reflector 3 as a reference, the subsequent three reflectors 2 or reflectors 3 are rotated 90 degrees in sequence, the angle between the first reflector 1 and the first reflector 2 is 45 degrees, and the angle between the first co-frequency modulated reflector and the first reflector 3 is 45 degrees.

[0012] The present invention also provides a laser micro-arc composite coaxial welding method based on co-frequency modulation, based on the above-mentioned laser micro-arc composite coaxial welding device based on co-frequency modulation, comprising the following steps: Step 1: Turn on the pulse micro-arc welding machine through the control system, install the welding wire reel, and adjust the welding wire extension length; Step 2: Adjust the height of the laser-micro-arc coaxial welding head according to the welding position; Step 3: Input the base material brand, welding wire model and welding wire diameter into the control system; Step 4: Identify the gap width of the weldment, and the control system determines the positions of the four-beam semiconductor laser spot, the four-beam fiber laser spot, and the wire feeding speed, pulse width, and pulse time of the pulse micro-arc welding machine according to the gap width of the weldment; Step 5: According to the set pulse width and pulse time, set the same-frequency adjustment angle and adjustment time of the same-frequency modulation reflector; Step six: The control system starts the fiber laser heat source system, the semiconductor laser heat source system and the pulse micro-arc welding machine to start the laser micro-arc coaxial welding. During the welding process, the four-beam fiber laser beam assisted arc droplet transition stage and the laser welding stage are carried out periodically.

[0013] Preferably, the auxiliary arc droplet transition stage is the arc starting stage, and the angles of four relatively independent co-frequency modulated reflectors are adjusted in the arc starting stage to achieve the simultaneous action of four split fiber laser beams on the end of the welding wire to assist the pulse micro-arc welding machine in arc starting; The laser welding stage is the arc closing stage. In the arc closing stage, the same-frequency modulated reflector is adjusted to realize that the fiber laser beam one after splitting moves forward, the fiber laser beam three after splitting moves backward, the fiber laser beam two after splitting moves left relative to the welding direction, and the fiber laser beam four after splitting moves right relative to the welding direction. The four fiber laser beams act on the molten pool together to achieve welding.

[0014] Preferably, in the arc starting stage, the energy P of the fiber laser beam acting on the welding wire is 焊丝 It is expressed as follows: P 焊丝 =P A ×A1%+P B ×B1%+P C ×C1%+P D ×D1%; In the arc closing stage, the energy P of the fiber laser beam acting on the weldment 焊件 It is expressed as follows: P 焊件 =P A ×A2%+P B ×B2%+P C ×C2%+P D ×D2%; A1%+A2%=α, α is the absorption rate of the welding wire and the weld metal to the energy of the fiber laser beam. Among them, P A , P B , P C , P D are the energies of fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four after splitting, respectively; A1%, B1%, C1%, and D1% represent the absorptivity of welding wire to fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four, respectively; A2%, B2%, C2%, and D2% represent the absorptivity of weldment to fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four, respectively; the absorptivity is determined by controlling the angle of the same-frequency modulated reflector.

[0015] Therefore, the present invention adopts the above-mentioned laser micro-arc composite coaxial welding device and method based on co-frequency modulation, which has the following beneficial effects: The present invention realizes the same-frequency adjustment of the relative position of the fiber laser spot and the micro-arc welding wire through the same-frequency modulation reflector, so as to realize the stable one-pulse-one-droplet molten droplet transition in the laser-micro-arc coaxial welding process; through the same-frequency modulation of the laser beam and the micro-arc, it is ensured that the four-beam fiber laser beam-assisted arc molten droplet transition and the laser welding are carried out periodically during the welding process, which can solve the problems of the inability to weld and the poor welding performance of large gap welding joints.

[0016] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the device according to an embodiment of the present invention; Figure 2 A schematic diagram of the position distribution of a reflector according to an embodiment of the present invention; Figure 3 A schematic diagram of the position distribution of the second reflector according to an embodiment of the present invention; Figure 4 A schematic diagram of energy modulation of a composite heat source according to an embodiment of the present invention; Figure 5 It is a structural schematic diagram of a welding wire output device according to an embodiment of the present invention; Figure 6 Schematic diagram of the card block structure of an embodiment of the present invention.

[0018] Reference numerals 1. Fiber laser heat source system; 11. Fiber laser; 12. Transmission fiber 1; 13. Fiber laser 1-to-4 beam splitter; 14. Fiber laser beam; 141. Fiber laser beam 1; 142. Fiber laser beam 2; 143. Fiber laser beam 3; 144. Fiber laser beam 4; 15. Reflector 1; 16. Same frequency modulation reflector; 2. Semiconductor laser heat source system; 21. Semiconductor laser; 22. Transmission optical fiber 2; 23. Semiconductor laser one-to-four beam splitter; 24. Semiconductor laser beam; 241. Semiconductor laser beam one; 242. Semiconductor laser beam two; 243. Semiconductor laser beam three; 244. Semiconductor laser beam four; 25. Reflector 2; 26. Reflector 3; 3. Pulse micro-arc welding machine; 4. Welding wire output device; 41. Welding wire reel; 42. Rotating shaft; 43. Clamp block; 44. Driven guide roller; 5. Protective gas cylinder; 6. Pulse micro-arc welding gun; 7. Welding wire; 8. Laser-micro-arc coaxial welding head. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0020] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0021] Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Example like Figure 1 As shown, a laser micro-arc composite coaxial welding device based on co-frequency modulation described in the present invention includes a fiber laser heat source system 1, a semiconductor laser heat source system 2, a pulse micro-arc welder 3, a control system and a laser-micro-arc coaxial welding head 8. The pulse micro-arc welder 3 is arranged inside the laser-micro-arc coaxial welding head 8, and its main structure avoids the beam transmission path in spatial design. The control system is electrically connected to the fiber laser heat source system 1, the semiconductor laser heat source system 2, and the pulse micro-arc welder 3 through a signal line using an existing structure, and controls each system.

[0025] The fiber laser heat source system 1 is used to generate a fiber laser beam 14. A portion of the energy of the fiber laser beam acts on the welding wire 7 to assist arc starting, and the other portion of the energy acts on the weldment to achieve deep melting welding of the metal. The fiber laser heat source system 1 includes a fiber laser 11 connected to the laser-micro arc coaxial welding head 8, and a fiber laser one-to-four beam splitter 13, a reflector 15, and a co-frequency modulated reflector 16 arranged inside the laser-micro arc coaxial welding head 8. The fiber laser 11 is connected to the fiber laser one-to-four beam splitter 13 through a transmission fiber 12, and the reflector 15 and the co-frequency modulated reflector 16 are arranged below the fiber laser one-to-four beam splitter 13. After the fiber laser beam 14 generated by the fiber laser 11 is split by the fiber laser one-to-four beam splitter 13, it is focused on the end of the welding wire 7 through the reflector 15 and the co-frequency modulated reflector 16 in turn. The split fiber laser beam 14 includes a fiber laser beam 1 141 , a fiber laser beam 2 142 , a fiber laser beam 3 143 , and a fiber laser beam 4 144 .

[0026] The semiconductor laser heat source system 2 is used to generate a semiconductor laser beam 24 to act on the weldment to increase the melting amount of the base metal of the weldment joint to be welded. The semiconductor laser heat source system 2 includes a semiconductor laser 21 connected to the laser-micro-arc coaxial welding head 8 and a semiconductor laser one-to-four beam splitter 23, a second reflector 25, and a third reflector 26 arranged inside the laser-micro-arc coaxial welding head 8. The semiconductor laser 21 is connected to the semiconductor laser one-to-four beam splitter 23 through a transmission optical fiber 22, and the second reflector 25 and the third reflector 26 are arranged below the semiconductor laser one-to-four beam splitter 23. After the semiconductor laser beam 24 generated by the semiconductor laser 21 is split by the semiconductor laser one-to-four beam splitter 23, it acts on the surface of the weldment through the second reflector 25 and the third reflector 26 in turn. The split semiconductor laser beam 24 includes a semiconductor laser beam one 241, a semiconductor laser beam two 242, a semiconductor laser beam three 243, and a semiconductor laser beam four 244.

[0027] like Figure 2 , Figure 3 As shown, four reflectors 15 and four reflectors 16 are provided, and are evenly arranged around the pulse micro-arc welding machine 3. Four reflectors 25 and four reflectors 3 26 are provided, and are evenly arranged around the pulse micro-arc welding machine 3. The first reflector 1 15 or the same frequency modulated reflector 16 is used as a reference, and the subsequent three reflectors 1 15 or the same frequency modulated reflectors 16 are rotated 90 degrees in sequence. The first reflector 2 25 or the reflector 3 26 is used as a reference, and the subsequent three reflectors 2 25 or the reflector 3 26 are rotated 90 degrees in sequence. The angle between the first reflector 1 15 and the first reflector 2 25 is 45 degrees, and the angle between the first same frequency modulated reflector 16 and the first reflector 3 26 is 45 degrees.

[0028] The same frequency modulated reflector 16 is arranged on a mirror seat, and a rotating shaft rotatably connected to the inner wall of the laser-micro-arc coaxial welding head 8 is arranged on the mirror seat, and the rotating shaft is driven to rotate by a driving element such as a driving motor to realize automatic angle adjustment of the same frequency modulated reflector 16. Reflector 1 15, reflector 2 25, and reflector 3 26 are all fixed by the mirror seat.

[0029] The pulse micro-arc welding machine 3 is used to generate a pulse micro-arc, and cooperates with the fiber laser beam 14 to adjust the same frequency to achieve arc starting and stable melting of the welding wire 7. The pulse micro-arc welding machine 3 is provided with a welding wire output device 4 for conveying the welding wire 7. The pulse micro-arc welding machine 3 is connected to the shielding gas cylinder 5 through a conveying pipe. The shielding gas cylinder 5 is filled with shielding gas. The bottom end of the pulse micro-arc welding machine 3 is provided with a pulse micro-arc welding gun 6. Figure 5 , Figure 6As shown, the welding wire output device 4 includes a welding wire reel 41, and the welding wire 7 is wound on the welding wire reel 41. A rotating shaft 42 is arranged at the center of the welding wire reel 41, and the rotating shaft 42 is connected to the output shaft of the welding wire feeding motor. The welding wire reel 41 can be removed from the rotating shaft 42, and the welding wire reel 41 is fixed to the rotating shaft 42 through the slot of the clamping block 43. The output shaft of the welding wire feeding motor drives the rotating shaft 42 to rotate and then drives the welding wire reel 41 to rotate, so as to feed the welding wire 7. The welding wire output device 4 is also provided with a plurality of driven guide rollers 44 for guiding and feeding the welding wire 7.

[0030] The control system adopts the existing structure, and the control system includes a semiconductor laser control module, a fiber laser control module, a micro-arc welding control module, an online monitoring module, etc. The semiconductor laser control module is used to control the semiconductor laser heat source system 2, control the generation and stop of the semiconductor laser beam 24, control the semiconductor laser power, etc. The fiber laser control module is used to control the fiber laser heat source system 1, control the generation and stop of the fiber laser beam 14, control the fiber laser power, adjust the deflection angle of the same frequency modulated reflector 16, etc. The micro-arc welding control module is used to control the pulse micro-arc welding machine 3, control the die feeding speed, the generated arc current, the arc voltage, etc. The online monitoring module is used to monitor each system and the welding process in real time, and cooperate with each module to make corresponding adjustments to each system.

[0031] The laser-micro-arc coaxial welding head 8 is provided with a structured light measuring instrument and a visual scanner for identifying the gap size of the weldment and feeding back to the control system. The control system feeds back various process parameters and the relative positions of the eight laser beams according to the metal material type, plate thickness and gap size of the weldment.

[0032] The pulse micro-arc welding machine 3 is not structurally different from the existing welding machines. Compared with the commonly used MIG welding machine (MIG welding machine automatically matches the appropriate welding current according to the set wire feeding speed), it can control each system through the control system to achieve the matching of low current and wire feeding speed. For the pulse micro-arc welding machine 3, according to the wire feeding speed, the control system will automatically match "fiber laser power + arc current * arc voltage", and then feed back the signal to the corresponding fiber laser control module and micro-arc welding control module, and then the corresponding module controls the corresponding system to achieve laser beam assisted arc starting of welding wire.

[0033] The laser micro-arc composite coaxial welding method based on co-frequency modulation described in the present invention is based on the above-mentioned laser micro-arc composite coaxial welding device based on co-frequency modulation, and comprises the following steps: Step one, open the pulse micro-arc welding machine 3 through the control system, install the wire reel 41, and adjust the dry extension length of the welding wire 7; the pulse micro-arc welding machine 3 itself is provided with a box door with a switching function. After opening the box door, the wire reel 41 is installed through an existing robot or machine tool.

[0034] Step 2: Adjust the height of the laser-micro-arc coaxial welding head by a robot or machine tool according to the welding position; Step 3: Input the base material brand, welding wire 7 model and welding wire 7 diameter in the control system; Step 4: Identify the gap width of the weldment, and the control system determines the positions of the four-beam semiconductor laser spot, the four-beam fiber laser spot, and the wire feeding speed, pulse width, and pulse time of the pulse micro-arc welding machine 3 according to the gap width of the weldment; Step 5: according to the set pulse width and pulse time, set the same frequency adjustment angle and adjustment time of the same frequency modulation reflector 16; Step six: the control system starts the fiber laser heat source system 1, the semiconductor laser heat source system 2 and the pulse micro-arc welder 3, and starts the laser micro-arc coaxial welding. During the welding process, the four fiber laser beams 14 assist the arc droplet transition stage and the laser welding stage are carried out periodically.

[0035] like Figure 4 As shown, the auxiliary arc droplet transition stage is the arc starting stage, and the angles of four relatively independent frequency modulated reflectors 16 are adjusted in the arc starting stage to achieve four split fiber laser beams 14 acting on the end of the welding wire 7 at the same time, assisting the pulse micro-arc welding machine 3 in arc starting; The laser welding stage is the arc closure stage. In the arc closure stage, the same frequency modulated reflector 16 is adjusted to realize the forward movement of the optical fiber laser beam 1 141 after splitting, the backward movement of the optical fiber laser beam 3 143 after splitting, the left movement of the optical fiber laser beam 2 142 after splitting relative to the welding direction, and the right movement of the optical fiber laser beam 4 144 after splitting relative to the welding direction. The four optical fiber laser beams 14 act on the molten pool together to realize welding. The arc starting and arc closure processes are repeated to realize welding.

[0036] In the arc starting stage, the energy P of the fiber laser beam 14 acting on the welding wire 7 is 焊丝 It is expressed as follows: P 焊丝 =P A ×A1%+P B ×B1%+P C ×C1%+P D ×D1%; In the arc closing stage, the energy P of the fiber laser beam 14 acting on the weldment 焊件 It is expressed as follows: P 焊件 =P A ×A2%+P B ×B2%+P C ×C2%+P D ×D2%; A1%+A2%=α, α is the absorption rate of the welding wire and the weld metal to the energy of the fiber laser beam; Among them, P A , P B , P C , P D They are the energies of the fiber laser beam 1 141, the fiber laser beam 2 142, the fiber laser beam 3 143, and the fiber laser beam 4 144 after splitting, respectively; A1%, B1%, C1%, and D1% represent the absorption rates of the welding wire 7 to the fiber laser beam 141, the fiber laser beam 2 142, the fiber laser beam 3 143, and the fiber laser beam 4 144, respectively; A2%, B2%, C2%, and D2% represent the absorption rates of the weldment to the fiber laser beam 141, the fiber laser beam 2 142, the fiber laser beam 3 143, and the fiber laser beam 4 144, respectively; the absorption rates are determined by controlling the angle of the co-frequency modulated reflector 16.

[0037] Therefore, the present invention adopts the above-mentioned laser micro-arc composite coaxial welding device and method based on co-frequency modulation. Through the co-frequency modulation of the laser beam and the micro-arc, the fiber laser beam 14 assists the arc droplet transition and the laser welding to be carried out periodically, thereby solving the problem of the inability to weld and poor welding performance of large gap welding joints.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A laser micro-arc composite coaxial welding device based on co-frequency modulation, characterized in that: include The fiber laser heat source system is used to generate a fiber laser beam, which acts on the welding wire to assist in arc starting and on the weldment to achieve deep metal penetration welding; Semiconductor laser heat source system, used to generate semiconductor laser beam to act on the weldment, increasing the melting amount of the base metal of the weldment joint to be welded; Pulse micro-arc welding machine is used to generate pulse micro-arc and achieve arc starting and welding wire melting in conjunction with the same frequency adjustment of the fiber laser beam; The control system is connected with the fiber laser heat source system, semiconductor laser heat source system, and pulse micro-arc welding machine through signal lines, and controls each system; Laser-micro-arc coaxial welding head, the pulse micro-arc welding machine is arranged inside the laser-micro-arc coaxial welding head, and the laser-micro-arc coaxial welding head is provided with a structured light measuring instrument and a visual scanner for identifying the gap size of the weldment.

2. The laser micro-arc composite coaxial welding device based on co-frequency modulation according to claim 1 is characterized in that: The fiber laser heat source system includes a fiber laser connected to a laser-micro-arc coaxial welding head, and a fiber laser one-to-four beam splitter, a reflector one, and a frequency-modulated reflector arranged inside the laser-micro-arc coaxial welding head. The fiber laser is connected to the fiber laser one-to-four beam splitter through a transmission fiber one, and the reflector one and the frequency-modulated reflector are arranged below the fiber laser one-to-four beam splitter. The fiber laser beam generated by the fiber laser is split by a fiber laser one-to-four beam splitter, and then is focused on the end of the welding wire through a reflector one and a frequency-modulated reflector in sequence. The split fiber laser beam includes a fiber laser beam one, a fiber laser beam two, a fiber laser beam three, and a fiber laser beam four.

3. The laser micro-arc hybrid coaxial welding device based on co-frequency modulation according to claim 2 is characterized in that: The semiconductor laser heat source system includes a semiconductor laser connected to the laser-micro-arc coaxial welding head, and a semiconductor laser one-to-four beam splitter, a second reflector, and a third reflector arranged inside the laser-micro-arc coaxial welding head. The semiconductor laser is connected to the semiconductor laser one-to-four beam splitter through a second transmission optical fiber, and the second reflector and the third reflector are arranged below the semiconductor laser one-to-four beam splitter. The semiconductor laser beam generated by the semiconductor laser is split by a semiconductor laser one-to-four beam splitter, and then acts on the surface of the weldment through reflector two and reflector three in sequence. The split semiconductor laser beam includes semiconductor laser beam one, semiconductor laser beam two, semiconductor laser beam three, and semiconductor laser beam four.

4. The laser micro-arc composite coaxial welding device based on co-frequency modulation according to claim 3 is characterized in that: A welding wire output device for conveying welding wire is arranged inside the pulse micro-arc welding machine. The welding wire output device comprises a welding wire reel. A rotating shaft is arranged at the center of the welding wire reel. The rotating shaft is connected to the output shaft of the welding wire conveying motor. The pulse micro-arc welding machine is connected to a shielding gas cylinder through a conveying pipe. The shielding gas cylinder is filled with shielding gas. A pulse micro-arc welding gun is arranged at the bottom end of the pulse micro-arc welding machine.

5. The laser micro-arc hybrid coaxial welding device based on co-frequency modulation according to claim 4 is characterized in that: The same-frequency modulated reflector is arranged on a mirror seat, and a rotating shaft which is rotatably connected with the inner wall of the laser-micro-arc coaxial welding head is arranged on the mirror seat.

6. The laser micro-arc hybrid coaxial welding device based on co-frequency modulation according to claim 5 is characterized in that: There are four reflectors and four frequency modulated reflectors, which are evenly arranged around the pulse micro-arc welding machine. Taking the first reflector or the frequency modulated reflector as the reference, the following three reflectors or the frequency modulated reflectors are rotated 90 degrees in sequence.

7. The laser micro-arc hybrid coaxial welding device based on co-frequency modulation according to claim 6 is characterized in that: There are four reflectors two and three, which are evenly arranged around the pulse micro-arc welding machine. Taking the first reflector two or reflector three as the reference, the subsequent three reflectors two or reflectors three are rotated 90 degrees in sequence, the angle between the first reflector one and the first reflector two is 45 degrees, and the angle between the first co-frequency modulated reflector and the first reflector three is 45 degrees.

8. A laser micro-arc composite coaxial welding method based on co-frequency modulation, characterized in that: The laser micro-arc composite coaxial welding device based on co-frequency modulation described in claims 1 to 7 comprises the following steps: Step 1: Turn on the pulse micro-arc welding machine through the control system, install the welding wire reel, and adjust the welding wire extension length; Step 2: Adjust the height of the laser-micro-arc coaxial welding head according to the welding position; Step 3: Input the base material brand, welding wire model and welding wire diameter into the control system; Step 4: Identify the gap width of the weldment, and the control system determines the positions of the four-beam semiconductor laser spot, the four-beam fiber laser spot, and the wire feeding speed, pulse width, and pulse time of the pulse micro-arc welding machine according to the gap width of the weldment; Step 5: According to the set pulse width and pulse time, set the same-frequency adjustment angle and adjustment time of the same-frequency modulation reflector; Step six: The control system starts the fiber laser heat source system, the semiconductor laser heat source system and the pulse micro-arc welding machine to start the laser micro-arc coaxial welding. During the welding process, the four-beam fiber laser beam assisted arc droplet transition stage and the laser welding stage are carried out periodically.

9. The laser micro-arc hybrid coaxial welding method based on co-frequency modulation according to claim 8 is characterized in that: The auxiliary arc droplet transition stage is the arc starting stage. In the arc starting stage, the angles of four relatively independent co-frequency modulated reflectors are adjusted to achieve the simultaneous action of four split fiber laser beams on the end of the welding wire to assist the pulse micro-arc welding machine in arc starting. The laser welding stage is the arc closing stage. In the arc closing stage, the same-frequency modulated reflector is adjusted to realize that the fiber laser beam one after splitting moves forward, the fiber laser beam three after splitting moves backward, the fiber laser beam two after splitting moves left relative to the welding direction, and the fiber laser beam four after splitting moves right relative to the welding direction. The four fiber laser beams act on the molten pool together to achieve welding.

10. The laser micro-arc hybrid coaxial welding method based on co-frequency modulation according to claim 9, characterized in that: In the arc starting stage, the energy P of the fiber laser beam acting on the welding wire 焊丝 It is expressed as follows: P 焊丝 =P A ×A1%+P B ×B1%+P C ×C1%+P D ×D1%; In the arc closing stage, the energy P of the fiber laser beam acting on the weldment 焊件 It is expressed as follows: P 焊件 =P A ×A2%+P B ×B2%+P C ×C2%+P D ×D2%; A1%+A2%=α, α is the absorption rate of the welding wire and the weld metal to the energy of the fiber laser beam; Among them, P A , P B , P C , P D are the energies of fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four after splitting, respectively; A1%, B1%, C1%, and D1% represent the absorptivity of welding wire to fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four, respectively; A2%, B2%, C2%, and D2% represent the absorptivity of weldment to fiber laser beam one, fiber laser beam two, fiber laser beam three, and fiber laser beam four, respectively; the absorptivity is determined by controlling the angle of the same-frequency modulated reflector.

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