A laser micro-arc composite coaxial welding device and method based on co-frequency modulation

Abstract

The present invention discloses a laser micro-arc composite coaxial welding device and method based on co-frequency modulation, belonging to the field of laser welding, including: an optical fiber laser heat source system for generating an optical fiber laser beam to act on the welding wire to assist in arc starting and welding of the welded part; a semiconductor laser heat source system for increasing the metal melting amount of the large-gap joint to be welded; a pulsed micro-arc welding machine for generating pulsed micro-arcs to cooperatively adjust the co-frequency with the optical fiber laser beam; a control system for controlling each system; a laser-micro-arc coaxial welding head, and the pulsed micro-arc welding machine is arranged inside the laser-micro-arc coaxial welding head; a structured light measuring instrument and a vision scanner are arranged on the laser-micro-arc coaxial welding head for identifying the gap size of the welded part. The present invention realizes the periodic development of the optical fiber laser beam-assisted arc droplet transfer and laser welding through the co-frequency modulation of the laser beam and the micro-arc, and solves the problems of impossible welding and poor welding performance of large-gap welded joints.

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 frequency modulation. Background Art

[0002] Laser welding is an efficient and precise welding method that uses a laser beam with a high energy density as a heat source. Laser welding irradiates a high-intensity laser beam onto the metal surface. 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 the metal can be heated to the melting point or even vaporized instantly, thus realizing welding.

[0003] Large-gap laser welding refers to a welding process in which the gap of the weld seam is large, usually exceeding the range that can be tolerated by traditional welding methods. Large-gap laser welding has the following difficulties:

[0004] High welding difficulty: Due to the large gap, a higher energy density is required to melt and connect the materials, making the welding more difficult;

[0005] High welding quality requirements: Large-gap welding needs to ensure the strength and tightness of the weld seam, and the welding quality requirements must meet the use requirements of the product. Summary of the Invention

[0006] The purpose of the present invention is to provide a laser micro-arc composite coaxial welding device and method based on frequency modulation. Through the frequency modulation of the laser beam and the micro-arc, the fiber laser beam-assisted arc droplet transfer and laser welding are carried out periodically, so as to solve the problems of inability to weld and poor welding performance of large-gap welded joints.

[0007] To achieve the above purpose, the present invention provides a laser micro-arc composite coaxial welding device based on frequency modulation, including

[0008] A fiber laser heat source system for generating a fiber laser beam. A part of the energy of the fiber laser beam acts on the welding wire to assist in arc starting, and another part of the energy acts on the workpiece to achieve deep penetration welding of the metal;

[0009] A semiconductor laser heat source system for generating a semiconductor laser beam to act on the workpiece to increase the melting amount of the base metal of the welded joint to be welded on the workpiece;

[0010] A pulsed micro-arc welding machine for generating pulsed micro-arcs and realizing arc starting and stable melting of the welding wire in cooperation with the frequency adjustment of the fiber laser beam;

[0011] A control system, which is connected to the fiber laser heat source system, the semiconductor laser heat source system, and the pulsed micro-arc welding machine through signal lines and controls each system;

[0012] Laser - micro - arc coaxial welding head, a pulsed micro - arc welding machine is arranged inside the laser - micro - arc coaxial welding head, and a structured light measuring instrument and a vision scanner are arranged on the laser - micro - arc coaxial welding head for identifying the gap size of the weldment.

[0013] Preferably, the fiber laser heat source system includes a fiber laser connected to the laser - micro - arc coaxial welding head, a fiber laser one - to - four beam splitter, a first mirror, and a co - frequency modulation mirror 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 first transmission fiber. The first mirror and the co - frequency modulation mirror are arranged below the fiber laser one - to - four beam splitter;

[0014] After the fiber laser beam generated by the fiber laser is split by the fiber laser one - to - four beam splitter, it passes through the first mirror and the co - frequency modulation mirror in sequence and is focused on the end of the welding wire. The split fiber laser beams include a first fiber laser beam, a second fiber laser beam, a third fiber laser beam, and a fourth fiber laser beam.

[0015] Preferably, the semiconductor laser heat source system includes a semiconductor laser connected to the laser - micro - arc coaxial welding head, a semiconductor laser one - to - four beam splitter, a second mirror, and a third mirror 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 fiber. The second mirror and the third mirror are arranged below the semiconductor laser one - to - four beam splitter;

[0016] After the semiconductor laser beam generated by the semiconductor laser is split by the semiconductor laser one - to - four beam splitter, it acts on the surface of the weldment through the second mirror and the third mirror in sequence. The split semiconductor laser beams include a first semiconductor laser beam, a second semiconductor laser beam, a third semiconductor laser beam, and a fourth semiconductor laser beam.

[0017] Preferably, a welding wire output device for conveying the welding wire is arranged inside the pulsed micro - arc welding machine. The welding wire output device includes 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 pulsed micro - arc welding machine is connected to a protective gas cylinder through a conveying pipe. The protective gas cylinder is filled with a protective gas. A pulsed micro - arc welding torch is arranged at the bottom of the pulsed micro - arc welding machine.

[0018] Preferably, the co - frequency modulation mirror 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.

[0019] Preferably, there are four first mirrors and co - frequency modulation mirrors each, and they are evenly arranged around the pulsed micro - arc welding machine; taking the first first mirror or co - frequency modulation mirror as a reference, the subsequent three first mirrors or co - frequency modulation mirrors are sequentially rotated 90 degrees.

[0020] Preferably, there are four second reflectors and four third reflectors, which are evenly arranged around the pulsed micro-arc welding machine; taking the first second reflector or third reflector as a reference, the subsequent three second reflectors or third reflectors are successively rotated 90 degrees, and the included angle between the first first reflector and the first second reflector is 45 degrees, and the included angle between the first co-frequency modulation reflector and the first third reflector is 45 degrees.

[0021] 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, the method includes the following steps:

[0022] Step 1: Turn on the pulsed micro-arc welding machine through the control system, install the wire spool, and adjust the wire dry elongation.

[0023] Step 2: Adjust the height of the laser-micro-arc coaxial welding head according to the welding position.

[0024] Step 3: Input the base metal grade, wire type and wire diameter into the control system.

[0025] Step 4: Identify the weld joint gap width, and the control system determines the positions of the four semiconductor laser spots, the positions of the four fiber laser spots, the wire feeding speed, the pulse width, and the pulse time of the pulsed micro-arc welding machine according to the weld joint gap width.

[0026] Step 5: Set the co-frequency adjustment angle and adjustment time of the co-frequency modulation reflector according to the set pulse width and pulse time.

[0027] Step 6: The control system controls the start of the fiber laser heat source system, the semiconductor laser heat source system and the pulsed micro-arc welding machine, and starts laser micro-arc coaxial welding. During the welding process, the four fiber laser beams assist the arc droplet transfer stage and the laser welding stage to develop periodically.

[0028] Preferably, the auxiliary arc droplet transfer stage is the arc starting stage. During the arc starting stage, the angles of the four relatively independent co-frequency modulation reflectors are adjusted to enable the four fiber laser beams after splitting to act on the end of the wire simultaneously, assisting the pulsed micro-arc welding machine to start the arc.

[0029] The laser welding stage is the arc ending stage. During the arc ending stage, the co-frequency modulation reflector is adjusted to enable the first split fiber laser beam to move forward, the third split fiber laser beam to move backward, the second split fiber laser beam to move left relative to the welding direction, and the fourth split fiber laser beam to move right relative to the welding direction. The four fiber laser beams act on the molten pool together to achieve welding.

[0030] Preferably, during the arc starting stage, the energy P of the fiber laser beam acting on the wire ,

[0029] ,

[0024] , ,

[0028] ,

[0023] , ,

[0022] , , 焊丝 , , , ,

[0027] , ,

[0031] ,

[0026] , ,

[0030] ,

[0025] , is expressed as follows:

[0031] P焊丝 =P A ×A1% + P B ×B1% + P C ×C1% + P D ×D1%;

[0032] During the arc ending stage, the energy P of the fiber laser beam acting on the welded part 焊件 is expressed as follows:

[0033] P 焊件 =P A ×A2% + P B ×B2% + P C ×C2% + P D ×D2%;

[0034] A1% + A2% = α, where α is the absorption rate of the fiber laser beam energy to the laser energy by the welding wire and the welded part metal;

[0035] Among them, P A , P B , P C , P D are the energies of the first, second, third, and fourth fiber laser beams after beam splitting respectively. A1%, B1%, C1%, and D1% respectively represent the absorption rates of the welding wire to the first, second, third, and fourth fiber laser beams, and A2%, B2%, C2%, and D2% respectively represent the absorption rates of the welded part to the first, second, third, and fourth fiber laser beams. The absorption rate is determined by controlling the angle of the frequency modulation mirror.

[0036] Therefore, by adopting the above-mentioned laser micro-arc composite coaxial welding device and method based on frequency modulation, the present invention has the following beneficial effects:

[0037] The present invention realizes the frequency modulation of the relative position between the fiber laser spot and the micro-arc welding wire through the frequency modulation mirror, and realizes a stable one-drop-at-a-time droplet transfer in the laser-micro-arc coaxial welding process; through the frequency modulation of the laser beam and the micro-arc, it ensures that the four fiber laser beams assist the arc droplet transfer and the laser welding to be carried out periodically during the welding process, and can solve the problems of inability to weld and poor welding performance of large-gap welded joints.

[0038] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Brief Description of the Drawings

[0039] Figure 1 is the overall structural schematic diagram of the device in the embodiment of the present invention;

[0040] Figure 2Schematic diagram of the position distribution of the first mirror in the embodiment of the present invention;

[0041] Figure 3 Schematic diagram of the position distribution of the second mirror in the embodiment of the present invention;

[0042] Figure 4 Schematic diagram of the composite heat source energy modulation in the embodiment of the present invention;

[0043] Figure 5 Schematic diagram of the structure of the wire output device in the embodiment of the present invention;

[0044] Figure 6 Schematic diagram of the structure of the clamping block in the embodiment of the present invention.

[0045] Reference numerals

[0046] 1. Fiber laser heat source system; 11. Fiber laser; 12. First transmission fiber; 13. Fiber laser one-to-four beam splitter; 14. Fiber laser beam; 141. First fiber laser beam; 142. Second fiber laser beam; 143. Third fiber laser beam; 144. Fourth fiber laser beam; 15. First mirror; 16. Homogeneous frequency modulation mirror;

[0047] 2. Semiconductor laser heat source system; 21. Semiconductor laser; 22. Second transmission fiber; 23. Semiconductor laser one-to-four beam splitter; 24. Semiconductor laser beam; 241. First semiconductor laser beam; 242. Second semiconductor laser beam; 243. Third semiconductor laser beam; 244. Fourth semiconductor laser beam; 25. Second mirror; 26. Third mirror;

[0048] 3. Pulse micro-arc welding machine;

[0049] 4. Wire output device; 41. Wire spool; 42. Rotating shaft; 43. Clamping block; 44. Driven guide roller;

[0050] 5. Protection gas cylinder; 6. Pulse micro-arc welding torch; 7. Welding wire; 8. Laser-micro-arc coaxial welding head. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention more clearly understood, the following further describes the embodiments of the present invention in detail with reference to 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 used to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end.

[0052] It should be noted that the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or server that includes a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0053] Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0054] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0055] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] Embodiment

[0057] As Figure 1 shown, a laser micro-arc composite coaxial welding device based on co-frequency modulation according to the present invention includes a fiber laser heat source system 1, a semiconductor laser heat source system 2, a pulsed micro-arc welding machine 3, a control system, and a laser-micro-arc coaxial welding head 8. The pulsed micro-arc welding machine 3 is disposed inside the laser-micro-arc coaxial welding head 8, and its main structure avoids the beam transmission path in the 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 pulsed micro-arc welding machine 3 through signal lines using existing structures and controls each system.

[0058] The fiber laser heat source system 1 is used to generate a fiber laser beam 14. A part of the energy of the fiber laser beam acts on the welding wire 7 to assist in arc starting, and another part of the energy acts on the welded part to achieve deep penetration 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 first mirror 15, and a frequency-modulated mirror 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 first transmission fiber 12. The first mirror 15 and the frequency-modulated mirror 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 sequentially passes through the first mirror 15 and the frequency-modulated mirror 16 and is focused on the end of the welding wire 7. The split fiber laser beam 14 includes a first fiber laser beam 141, a second fiber laser beam 142, a third fiber laser beam 143, and a fourth fiber laser beam 144.

[0059] The semiconductor laser heat source system 2 is used to generate a semiconductor laser beam 24 that acts on the welded part to increase the melting amount of the base metal of the welded joint to be welded on the welded part. 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 mirror 25, and a third mirror 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 second transmission fiber 22. The second mirror 25 and the third mirror 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 sequentially passes through the second mirror 25 and the third mirror 26 and acts on the surface of the welded part. The split semiconductor laser beam 24 includes a first semiconductor laser beam 241, a second semiconductor laser beam 242, a third semiconductor laser beam 243, and a fourth semiconductor laser beam 244.

[0060] As Figure 2 、 Figure 3 shown, four first mirrors 15 and four frequency-modulated mirrors 16 are both arranged and evenly arranged around the pulse micro-arc welder 3. Four second mirrors 25 and four third mirrors 26 are both arranged and evenly arranged around the pulse micro-arc welder 3. Taking the first first mirror 15 or the frequency-modulated mirror 16 as a reference, the subsequent three first mirrors 15 or the frequency-modulated mirrors 16 are sequentially rotated 90 degrees. Taking the first second mirror 25 or the third mirror 26 as a reference, the subsequent three second mirrors 25 or the third mirrors 26 are sequentially rotated 90 degrees. The included angle between the first first mirror 15 and the first second mirror 25 is 45 degrees, and the included angle between the first frequency-modulated mirror 16 and the first third mirror 26 is 45 degrees.

[0061] The same-frequency modulation mirror 16 is arranged on the mirror base. A rotating shaft rotatably connected to the inner wall of the laser-micro-arc coaxial welding head 8 is arranged on the mirror base. The rotating shaft is driven to rotate by a driving element such as a driving motor, so as to realize the automatic angle adjustment of the same-frequency modulation mirror 16. The first mirror 15, the second mirror 25, and the third mirror 26 are all fixed through the mirror base.

[0062] The pulsed micro-arc welding machine 3 is used to generate pulsed micro-arc and cooperate with the same-frequency adjustment of the fiber laser beam 14 to achieve arc starting and stable melting of the welding wire 7. A welding wire output device 4 for conveying the welding wire 7 is arranged inside the pulsed micro-arc welding machine 3. The pulsed 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. A pulsed micro-arc welding torch 6 is arranged at the bottom of the pulsed micro-arc welding machine 3. As Figure 5 、 Figure 6 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 conveying motor. The welding wire reel 41 can be detached from the rotating shaft 42. The welding wire reel 41 is fixed to the rotating shaft 42 through a clamping block 43 and a clamping groove. The output shaft of the welding wire conveying motor drives the rotating shaft 42 to rotate, and then drives the welding wire reel 41 to rotate to convey the welding wire 7. The welding wire output device 4 is also provided with a plurality of driven guide rollers 44 for guiding and conveying the welding wire 7.

[0063] The control system adopts an existing structure. The control system includes a semiconductor laser control module, a fiber laser control module, a micro-arc welding control module, an on-line 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 modulation mirror 16, etc. The micro-arc welding control module is used to control the pulsed micro-arc welding machine 3, control the wire feeding speed, the generated arc current, the arc voltage, etc. The on-line monitoring module is used to monitor each system and the welding process in real time, and cooperate with each module to adjust each system accordingly.

[0064] A structured light measuring instrument and a vision scanner are arranged on the laser-micro-arc coaxial welding head 8, which are used to identify the gap size of the welded part and feedback it to the control system. The control system feeds back the relative position of each process parameter and eight laser beams according to the type of the metal material of the welded part, the plate thickness and the gap size.

[0065] The pulsed micro-arc welding machine 3 has no structural differences from existing welding machines. Compared with common MIG welding machines (MIG welding machines automatically match appropriate welding currents according to the set wire feeding speed), it can control each system through a control system to achieve the matching of small currents and wire feeding speeds. For the pulsed 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 feedback the signal to the corresponding fiber laser control module and micro-arc welding control module, and then the corresponding modules control the corresponding systems to achieve the starting of the arc assisted by the laser beam for the welding wire.

[0066] A laser micro-arc composite coaxial welding method based on frequency modulation according to the present invention, based on the above-mentioned laser micro-arc composite coaxial welding device based on frequency modulation, includes the following steps:

[0067] Step 1: Turn on the pulsed micro-arc welding machine 3 through the control system, install the wire spool 41, and adjust the dry elongation of the welding wire 7; The pulsed micro-arc welding machine 3 itself is provided with a cabinet door with a switching function. After opening the cabinet door, install the wire spool 41 through an existing robot or machine tool.

[0068] Step 2: Adjust the height of the laser-micro-arc coaxial welding head through a robot or machine tool according to the welding position;

[0069] Step 3: Input the base metal grade, welding wire 7 model, and welding wire 7 diameter into the control system;

[0070] Step 4: Identify the width of the weld joint gap. The control system determines the positions of the four semiconductor laser spots, the positions of the four fiber laser spots, and the wire feeding speed, pulse width, and pulse time of the pulsed micro-arc welding machine 3 according to the width of the weld joint gap;

[0071] Step 5: Set the frequency adjustment angle and adjustment time of the frequency modulation mirror 16 according to the set pulse width and pulse time;

[0072] Step 6: The control system controls the start of the fiber laser heat source system 1, the semiconductor laser heat source system 2, and the pulsed micro-arc welding machine 3 to start laser micro-arc coaxial welding. During the welding process, the four fiber laser beams 14 assist the arc droplet transfer stage and the laser welding stage to develop periodically.

[0073] As Figure 4 shown, the auxiliary arc droplet transfer stage is the arc starting stage. During the arc starting stage, adjust the angles of the four relatively independent frequency modulation mirrors 16 to enable the four fiber laser beams 14 after splitting to act on the end of the welding wire 7 simultaneously, assisting the pulsed micro-arc welding machine 3 to start the arc;

[0074] The laser welding stage is the arc extinguishing stage. During the arc extinguishing stage, the frequency modulation mirror 16 is adjusted to move the first fiber laser beam 141 after beam splitting forward, move the third fiber laser beam 143 after beam splitting backward, move the second fiber laser beam 142 after beam splitting to the left relative to the welding direction, and move the fourth fiber laser beam 144 after beam splitting to the right relative to the welding direction. The four fiber laser beams 14 act together on the molten pool to achieve welding. The arc starting and arc extinguishing processes are repeated to achieve welding.

[0075] During the arc starting stage, the energy P of the fiber laser beam 14 acting on the welding wire 7 焊丝 is expressed as follows:

[0076] P 焊丝 = P A × A1% + P B × B1% + P C × C1% + P D × D1%;

[0077] During the arc extinguishing stage, the energy P of the fiber laser beam 14 acting on the welded part 焊件 is expressed as follows:

[0078] P 焊件 = P A × A2% + P B × B2% + P C × C2% + P D × D2%;

[0079] A1% + A2% = α, where α is the absorption rate of the first fiber laser beam 141 by the welding wire and the welded part metal;

[0080] Among them, P A , P B , P C , P D are the energies of the first fiber laser beam 141, the second fiber laser beam 142, the third fiber laser beam 143, and the fourth fiber laser beam 144 after beam splitting respectively. A1%, B1%, C1%, and D1% respectively represent the absorption rates of the welding wire 7 for the first fiber laser beam 141, the second fiber laser beam 142, the third fiber laser beam 143, and the fourth fiber laser beam 144. A2%, B2%, C2%, and D2% respectively represent the absorption rates of the welded part for the first fiber laser beam 141, the second fiber laser beam 142, the third fiber laser beam 143, and the fourth fiber laser beam 144. The absorption rate is determined by controlling the angle of the frequency modulation mirror 16.

[0081] Therefore, the present invention adopts the above-mentioned laser micro-arc composite coaxial welding device and method based on frequency modulation. Through the frequency modulation of the laser beam and the micro-arc, it realizes the periodic development of the fiber laser beam 14-assisted arc droplet transfer and laser welding, and solves the problems of impossible welding and poor welding performance of large-gap welded joints.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent substitutions, and these modifications or equivalent substitutions cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A laser micro-arc composite coaxial welding method based on co-frequency modulation, characterized in that: The welding device applying the laser micro-arc composite coaxial welding method based on frequency modulation includes a fiber laser heat source system, which is used to generate a fiber laser beam and acts on the welding wire to assist in arc starting and acts on the weldment to achieve deep penetration metal welding; a semiconductor laser heat source system, which is used to generate a semiconductor laser beam and acts on the weldment to increase the melting amount of the base metal of the weld joint to be welded; a pulsed micro-arc welding machine, which is used to generate pulsed micro-arc and cooperate with the fiber laser beam for frequency modulation adjustment to achieve arc starting and melting of the welding wire; a control system, which is connected to the fiber laser heat source system, the semiconductor laser heat source system, and the pulsed micro-arc welding machine through signal lines and controls each system; a laser-micro-arc coaxial welding head, the pulsed micro-arc welding machine is arranged inside the laser-micro-arc coaxial welding head, and a structured light measuring instrument and a vision scanner are arranged on the laser-micro-arc coaxial welding head for identifying the gap size of the weldment; The fiber laser heat source system includes a fiber laser connected to the laser-micro-arc coaxial welding head, a fiber laser one-to-four beam splitter, a first mirror, and a frequency modulation mirror 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 first mirror and the frequency modulation mirror are arranged below the fiber laser one-to-four beam splitter; The fiber laser beam generated by the fiber laser is split by the fiber laser one-to-four beam splitter, and the split fiber laser beams include a fiber laser beam one, a fiber laser beam two, a fiber laser beam three, and a fiber laser beam four; A welding wire output device for conveying the welding wire is arranged inside the pulsed micro-arc welding machine. The welding wire output device includes a welding wire reel, a rotating shaft is arranged 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 laser micro-arc composite coaxial welding method based on frequency modulation includes the following steps: Step one, turn on the pulsed micro-arc welding machine through the control system, install the welding wire reel, and adjust the dry elongation of the welding wire; Step two: Adjust the height of the laser-micro-arc coaxial welding head according to the welding position; Step three: Input the base metal grade, welding wire model, and welding wire diameter into the control system; Step four: Identify the width of the weldment gap, and the control system determines the positions of the four semiconductor laser spots, the positions of the four fiber laser spots, the wire feeding speed, pulse width, and pulse time of the pulsed micro-arc welding machine according to the weldment gap width; Step five: Set the frequency modulation adjustment angle and adjustment time of the frequency modulation mirror according to the set pulse width and pulse time; Step six: The control system controls the start of the fiber laser heat source system, the semiconductor laser heat source system, and the pulsed micro-arc welding machine to start laser micro-arc coaxial welding. During the welding process, the four fiber laser beams assist the arc droplet transfer stage and the laser welding stage to carry out periodically; The auxiliary arc droplet transfer stage is the arc starting stage. In the arc starting stage, the angles of the four relatively independent frequency modulation mirrors are adjusted to enable the four split fiber laser beams to act on the end of the welding wire simultaneously to assist the pulsed micro-arc welding machine in starting the arc; The laser welding stage is the arc ending stage. In the arc ending stage, the same-frequency modulation mirror is adjusted to make the fiber laser beam 1 after beam splitting move forward, the fiber laser beam 3 after beam splitting move backward, the fiber laser beam 2 after beam splitting move left relative to the welding direction, and the fiber laser beam 4 after beam splitting move right relative to the welding direction. The four fiber laser beams act on the molten pool together to achieve welding.

2. The laser micro-arc composite coaxial welding method based on co-frequency modulation according to claim 1, wherein: The semiconductor laser heat source system includes a semiconductor laser connected to a laser-micro-arc coaxial welding head, and a semiconductor laser one-for-four beam splitter, a mirror 2, and a mirror 3 disposed inside the laser-micro-arc coaxial welding head. The semiconductor laser is connected to the semiconductor laser one-for-four beam splitter through a transmission fiber 2. The mirror 2 and the mirror 3 are disposed below the semiconductor laser one-for-four beam splitter. After the semiconductor laser beam generated by the semiconductor laser is split by the semiconductor laser one-for-four beam splitter, it acts on the surface of the workpiece through the mirror 2 and the mirror 3 in sequence. The semiconductor laser beams after beam splitting include a semiconductor laser beam 1, a semiconductor laser beam 2, a semiconductor laser beam 3, and a semiconductor laser beam 4.

3. The laser micro-arc composite coaxial welding method based on co-frequency modulation according to claim 1, characterized in that: The pulsed micro-arc welding machine is connected to a protective gas cylinder through a delivery pipe. The protective gas cylinder is filled with a protective gas. A pulsed micro-arc welding torch is disposed at the bottom of the pulsed micro-arc welding machine.

4. The laser micro-arc composite coaxial welding method based on co-frequency modulation according to claim 3, wherein: The same-frequency modulation mirror is disposed on a mirror base. A rotating shaft rotatably connected to the inner wall of the laser-micro-arc coaxial welding head is disposed on the mirror base.

5. The laser micro-arc composite coaxial welding method based on co-frequency modulation according to claim 4, characterized in that: Four mirror 1s and four same-frequency modulation mirrors are both disposed and evenly arranged around the pulsed micro-arc welding machine. Taking the first mirror 1 or the same-frequency modulation mirror as a reference, the subsequent three mirror 1s or the same-frequency modulation mirrors are sequentially rotated 90 degrees.

6. The laser micro-arc composite coaxial welding method based on co-frequency modulation according to claim 5, wherein: Four mirror 2s and four mirror 3s are both disposed and evenly arranged around the pulsed micro-arc welding machine. Taking the first mirror 2 or the mirror 3 as a reference, the subsequent three mirror 2s or the mirror 3s are sequentially rotated 90 degrees. The included angle between the first mirror 1 and the first mirror 2 is 45 degrees, and the included angle between the first same-frequency modulation mirror and the first mirror 3 is 45 degrees.

7. The laser micro-arc composite coaxial welding method based on same-frequency modulation according to claim 1, characterized in that: During the arc starting stage, the energy P of the fiber laser beam acting on the welding wire 焊丝 is expressed as follows: P 焊丝 = P A × A1% + P B × B1% + P C × C1% + P D × D1%; During the arc-extinguishing stage, the energy P of the fiber laser beam acting on the welded part 焊件 is expressed as follows: P 焊件 = P A × A2% + P B × B2% + P C × C2% + P D × D2%; A1% + A2% = α, where α is the absorption rate of the fiber laser beam 1 by the welding wire and the workpiece metal. Among them, P A , P B , P C , P D are the energies of the first, second, third, and fourth fiber laser beams after beam splitting, respectively. A1%, B1%, C1%, and D1% represent the absorption rates of the welding wire for the first, second, third, and fourth fiber laser beams respectively. A2%, B2%, C2%, and D2% represent the absorption rates of the welded part for the first, second, third, and fourth fiber laser beams respectively. The absorption rate is determined by controlling the angle of the co-frequency modulation mirror.

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