Coaxial double-beam welding method and coaxial double-beam welding equipment

Abstract

The invention discloses a coaxial double-beam welding method and coaxial double-beam welding equipment, and relates to the technical field of metal laser welding methods.The coaxial double-beam welding method comprises the following steps that S1, a to-be-welded workpiece is pretreated, and then the to-be-welded workpiece is fixed; s2, the continuous laser beam and the pulse laser beam are coaxially coupled into a composite laser beam, the spraying direction of molten pool shielding gas is adjusted, and the sprayed molten pool shielding gas is aligned to a molten pool; s3, the composite laser beam is adjusted, and the spot diameter d of the composite laser beam irradiating the molten pool is controlled; s4, the average output power and the defocusing amount of the continuous laser are set to be delta z2, the average output power and the defocusing amount of the pulse laser are set to be delta z2, and the frequency is f and the pulse width; and S5, welding is conducted, and meanwhile molten pool shielding gas is sprayed to the molten pool till welding is finished. Continuous laser and pulse laser are coaxially coupled to form a composite laser beam, the composite laser beam jointly acts on a molten pool, the temperature distribution gradient is accurately controlled by regulating and controlling the coaxial double-beam heat source state, and therefore the problem of thin plate welding deformation is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal laser welding methods, and particularly to a coaxial dual-beam welding method and a coaxial dual-beam welding device. Background Art

[0002] The thickness of the thin plate structure is low and the ability to resist stress deformation is poor. Therefore, the most easily encountered problems in thin plate welding are incomplete penetration caused by too low welding power, burn-through caused by too high welding power, and structural deformation caused by thermal stress during welding. Among them, welding deformation is a key problem that urgently needs to be solved. During the welding process, different cooling rates of the workpiece result in a large temperature gradient difference, so that non-uniform stress and strain are generated, ultimately leading to deformation. Summary of the Invention

[0003] The purpose of the present invention is to provide a coaxial dual-beam welding method and a coaxial dual-beam welding device to solve the problems existing in the above-mentioned prior art. A continuous laser and a pulsed laser are coaxially coupled into a composite laser beam, which acts on the molten pool together. By regulating the state of the coaxial dual-beam heat source, the temperature distribution gradient is precisely controlled to solve the problem of welding deformation of thin plates.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] The present invention provides a coaxial dual-beam welding method, including the following steps:

[0006] S1. Pretreat the workpiece to be welded, and then fix the workpiece to be welded;

[0007] S2. Adjust the axis directions of the continuous laser beam and the pulsed laser beam so that the continuous laser beam and the pulsed laser beam are coaxially coupled into a composite laser beam, and adjust the injection direction of the molten pool shielding gas so that the injected molten pool shielding gas is aligned with the molten pool;

[0008] S3. Adjust the composite laser beam and control the spot diameter d of the composite laser beam irradiated on the molten pool;

[0009] S4. Set the average output power of the continuous laser as P1, the defocus amount of the continuous laser as Δz1, set the average output power of the pulsed laser as P2, the defocus amount of the pulsed laser as Δz2, the pulsed laser frequency as f, and the pulsed laser pulse width as τ;

[0010] S5. Weld at a welding speed ν, and at the same time inject the molten pool shielding gas into the molten pool until the welding is completed.

[0011] In one embodiment, in step S2, it further includes adjusting the release direction of the heating zone protective gas so that the released heating zone protective gas covers the weld and the area where the temperature rises on the side of the weld; in step S5, before starting welding, the heating zone protective gas is released for a release time of t1, and after welding ends, the heating zone protective gas continues to be released for a release time of t2.

[0012] In one embodiment, in step S2, it further includes adjusting the release direction of the heating zone protective gas so that the released heating zone protective gas covers the weld and the area where the temperature rises on the side of the weld; in step S5, before starting welding, the heating zone protective gas is released for a release time of t1, and after welding ends, the heating zone protective gas continues to be released for a release time of t2.

[0013] In one embodiment, in step S2, the flow rate of the molten pool protective gas is 10 to 30 liters per minute, and the flow rate of the heating zone protective gas is 25 to 40 liters per minute.

[0014] In one embodiment, in step S3, the value range of the composite laser beam diameter d is from 1.0 mm to 4.0 mm.

[0015] In one embodiment, in step S4, the value range of the continuous laser average output power P1 is from 1400 W to 1800 W, the value range of the pulsed laser average output power P2 is from 200 W to 500 W, and the ratio A of P1 to P2 is 2.5 ≤ A ≤ 5.5. The value range of the continuous laser defocus amount Δz1 is from +2 mm to +10 mm, the value range of the pulsed laser defocus amount Δz2 is from +1 mm to +12 mm, and the ratio B of Δz1 to Δz2 is 0.5 ≤ B ≤ 2.5.

[0016] In one embodiment, in step S4, the value range of the pulsed laser frequency f is from 10 Hz to 100 Hz, and the value range of the pulsed laser pulse width τ is from 2 ms to 8 ms.

[0017] In one embodiment, the value range of the welding speed ν is from 700 mm per minute to 1500 mm per minute.

[0018] The present invention also provides a coaxial dual-beam welding device applied to the above coaxial dual-beam welding method, including a coaxial dual-beam laser head, a protective gas nozzle for spraying the molten pool protective gas, and a fixing seat for fixing the workpiece; the fixing seat includes a workpiece fixing surface, on which a fixator is provided, the workpiece is fixed on the workpiece fixing surface, the coaxial dual-beam laser head and the protective gas nozzle are arranged outside the workpiece, and during welding, the coaxial dual-beam laser head and the protective gas nozzle move synchronously along the welding direction.

[0019] In one embodiment, a drag shield is disposed on the surface of the workpiece and covers the weld seam. A heating zone protective gas release hole is provided on the side of the drag shield facing the workpiece. During welding, the drag shield moves synchronously with the coaxial double-beam laser head along the welding direction; an exhaust pipe for providing heating zone protective gas is disposed inside the fixed seat, and a ventilation hole for releasing heating zone protective gas is provided on the workpiece fixing surface.

[0020] In one embodiment, a condenser lens is disposed inside the coaxial double-beam laser head, and the pulsed laser beam and the continuous laser beam are combined into a composite laser beam that passes through the condenser lens.

[0021] The present invention has achieved the following technical effects compared with the prior art:

[0022] The present invention provides a coaxial double-beam welding method, which uses a continuous laser and a pulsed laser to be coaxially coupled into a composite laser beam, and jointly acts on the molten pool. By regulating the state of the coaxial double-beam heat source, the temperature distribution gradient is precisely controlled to solve the problem of thin plate welding deformation. Laser welding is an efficient and precise welding method that uses a high-energy density laser beam as a heat source, and has the advantages of high energy density, short welding time, and small heat affected zone. It is suitable for high-speed and precise welding of thin plates and will not cause welding deformation. The coaxial double-beam welding method is a technology that coaxially couples two laser beams to weld metal thin plates, which can be combined by two laser beams of the same or different types. The present invention combines a continuous laser and a pulsed laser. The continuous laser beam can provide basic welding energy, and the pulsed laser beam can intermittently provide supplementary energy to keep the temperature of the weld seam and the surrounding area of the weld seam stable and consistent during the welding process, significantly improving the absorption and utilization of laser energy by the workpiece, increasing the welding penetration and width, and improving the welding ability and efficiency of the material, providing new ideas and methods for welding thin plate type metal workpieces.

[0023] The present invention has also achieved the following technical effects compared with the prior art:

[0024] 1. In the present invention, a heating zone protective gas covering the weld seam and the area where the temperature rises on the side of the weld seam is also provided to isolate the heating zone from the air and prevent the workpiece substrate from reacting with components such as oxygen in the air at high temperature, resulting in changes in the composition of the workpiece substrate.

[0025] 2. The present invention also provides a coaxial double-beam welding device, which is applied to the above coaxial double-beam welding method, can stably fix the thin plate workpiece on the fixed seat, and complete coaxial double-beam welding.

[0026] 3. In the present invention, the drag shield and the exhaust pipe are respectively located on both sides of the workpiece, and the released heating zone protective gas can effectively cover the heating zone of the workpiece, improving the protection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0028] Figure 1 It is a schematic diagram of the overall structure of the coaxial double-beam welding device in the embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the structure of the coaxial double-beam laser head in the embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of the spot structure of the combined laser beam irradiating on the molten pool in the embodiment of the present invention.

[0031] Among them, 1. Coaxial double-beam laser head; 101. Condensing lens; 2. Shielding gas nozzle; 3. Fixed seat; 301. Fixator; 302. Exhaust pipe; 4. Workpiece; 5. Drag shield; 6. Pulsed laser beam; 7. Continuous laser beam. Specific embodiments

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Those familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that the structures, proportions, sizes, etc. depicted in the attached drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they do not have any substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the attached drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0034] It should also be noted that in the embodiments of the present application, the same reference numerals are used to represent the same component or the same part.

[0035] The object of the present invention is to provide a coaxial dual-beam welding method and a coaxial dual-beam welding device to solve the problems existing in the prior art. A continuous laser and a pulsed laser are coaxially coupled to form a composite laser beam, which acts on the molten pool together. By regulating the state of the coaxial dual-beam heat source, the temperature distribution gradient is precisely controlled to solve the problem of thin plate welding deformation.

[0036] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the attached drawings and specific embodiments.

[0037] Embodiment 1

[0038] As Figure 1 and Figure 2 shown, the present invention provides a coaxial dual-beam welding method, including the following steps:

[0039] S1. Pretreat the workpiece to be welded, and then fix the workpiece to be welded;

[0040] S2. Adjust the axial directions of the continuous laser beam 7 and the pulsed laser beam 6 so that the continuous laser beam 7 and the pulsed laser beam 6 are coaxially coupled into a composite laser beam, and adjust the injection direction of the molten pool protective gas so that the injected molten pool protective gas is aligned with the molten pool;

[0041] S3. Adjust the composite laser beam and control the spot diameter d of the composite laser beam irradiated on the molten pool;

[0042] S4. Set the average output power of the continuous laser as P1, the defocus amount of the continuous laser as Δz1, set the average output power of the pulsed laser as P2, the defocus amount of the pulsed laser as Δz2, the frequency of the pulsed laser as f, and the pulse width of the pulsed laser as τ;

[0043] S5. Weld at the welding speed ν, and at the same time spray shielding gas for the molten pool until the welding is completed.

[0044] The combination of the continuous laser and the pulsed laser. The continuous laser beam can provide basic welding energy, and the pulsed laser beam can intermittently provide supplementary energy, keeping the temperature of the weld and the area around the weld stable and consistent during the welding process, and significantly improving the absorption and utilization of laser energy by the workpiece. The shielding gas for the molten pool mainly covers the molten pool, providing immediate protection to prevent impurity gases such as oxygen from reacting with the welding position, resulting in a reduction in the strength of the generated weld. The shielding gas for the heating zone can cover the weld and the heating zone on the side of the weld, isolating the heating zone from the air, preventing impurity gases such as oxygen from reacting with the still-hot weld and the area near the weld, and avoiding the appearance of impurities such as rust. The defocus amount is the distance between the laser focus and the working material. The value of the defocus amount represents the distance between the laser focus and the working material along the laser axis direction. A positive defocus amount indicates that the laser focus is located outside the working material, and a negative defocus amount indicates that the laser focus is located inside the working material.

[0045] In one embodiment, the pretreatment includes deburring, decontamination, and polishing.

[0046] In one embodiment, in step S2, it further includes adjusting the release direction of the shielding gas for the heating zone so that the released shielding gas for the heating zone covers the weld and the area where the temperature rises on the side of the weld. In step S5, before starting welding, release the shielding gas for the heating zone, and the release time is t1. After the welding is completed, continue to release the shielding gas for the heating zone, and the release time is t2. Some materials will directly react with the components in the air at high temperatures. Therefore, it is not enough to only set gas protection at the molten pool position. Gas protection is also required in the weld and the high-temperature area around the weld to isolate the contact between the weld and the high-temperature area around the weld and the air. The function of releasing the shielding gas for the heating zone before welding is to create an air-insulated environment. The release time t1 only needs to be able to create an air-insulated environment. Continuing to release the shielding gas for the heating zone after welding can maintain the air-insulated environment, and the release time t2 is such that the weld and the high-temperature area around the weld cool down to no longer react with the air.

[0047] In one embodiment, in step S2, the flow rate of the shielding gas for the molten pool is 10 to 30 liters per minute, and the flow rate of the shielding gas for the heating zone is 25 to 40 liters per minute.

[0048] In one embodiment, in step S3, the value range of the diameter d of the composite laser beam is from 1.0 mm to 4.0 mm.

[0049] In one embodiment, in step S4, the value range of the average output power P1 of the continuous laser is from 1400 W to 1800 W, the value range of the average output power P2 of the pulsed laser is from 200 W to 500 W, and the ratio A of P1 to P2 is 2.5 ≤ A ≤ 5.5.

[0050] In one embodiment, in step S4, the value range of the defocus amount Δz1 of the continuous laser is from +2 mm to +10 mm, the value range of the defocus amount Δz2 of the pulsed laser is from +1 mm to +12 mm, and the ratio B of Δz1 to Δz2 is 0.5 ≤ B ≤ 2.5.

[0051] In one embodiment, in step S4, the value range of the frequency f of the pulsed laser is from 10 Hz to 100 Hz, and the value range of the pulse width τ of the pulsed laser is from 2 ms to 8 ms.

[0052] In one embodiment, the value range of the welding speed ν is from 700 mm per minute to 1500 mm per minute.

[0053] Embodiment 2

[0054] The present invention also provides a coaxial dual-beam welding device applied to the above coaxial dual-beam welding method, including a coaxial dual-beam laser head 1, a shielding gas nozzle 2 for injecting shielding gas for the molten pool, and a fixing base 3 for fixing the workpiece 4; the fixing base 3 includes a workpiece fixing surface, and a fixer 301 is arranged on the workpiece fixing surface. The workpiece 4 is fixed on the workpiece fixing surface. The coaxial dual-beam laser head 1 and the shielding gas nozzle 2 are arranged outside the workpiece 4. During welding, the coaxial dual-beam laser head 1 and the shielding gas nozzle 2 move synchronously along the welding direction. The workpiece 4 is a thin plate workpiece. During welding, a plurality of workpieces 4 are fixed on the fixing base 3 by the fixer 301. The coaxial dual-beam laser head 1 welds along the welding path, that is, the joint position of different workpieces 4. While welding, the shielding gas nozzle 2 injects shielding gas for the molten pool into the molten pool to protect the workpiece 4 in real time. The coaxial dual-beam laser head 1 and the shielding gas nozzle 2 move synchronously.

[0055] In one embodiment, the coaxial dual-beam laser head 1 and the shielding gas nozzle 2 are separately and independently arranged. The coaxial dual-beam laser head 1 and the shielding gas nozzle 2 can also be integrated on the same structure.

[0056] In one embodiment, the trailing shield 5 is disposed on the surface of the workpiece 4 and covers the weld seam. The side of the trailing shield 5 facing the workpiece 4 is provided with heating zone protective gas release holes. During welding, the trailing shield 5 moves synchronously with the coaxial double-beam laser head 1 along the welding direction. An exhaust pipe 302 for supplying heating zone protective gas is arranged in the fixed seat 3, and vent holes for releasing heating zone protective gas are formed in the workpiece fixing surface. The trailing shield 5 and the exhaust pipe 302 are respectively arranged on both sides of the workpiece 4, and the released heating zone protective gas can completely cover the weld seam and the area where the temperature rises on the side of the weld seam. The trailing shield 5 and the exhaust pipe 302 are connected to an external heating zone protective gas supply device.

[0057] In one embodiment, the exhaust pipe 302 is a copper pipe.

[0058] In one embodiment, a condenser lens 101 is arranged in the coaxial double-beam laser head 1. The pulsed laser beam 6 and the continuous laser beam 7 are combined into a composite laser beam and pass through the condenser lens 101. The condenser lens 101 has a condensing function, and adjusting the height of the condenser lens 101 can adjust the spot size of the focal position. The pulsed laser beam 6 and the continuous laser beam 7 respectively originate from different laser generators, and the optical path is adjusted by a refraction device to form a composite laser beam. The refraction device can be an existing prism refraction device.

[0059] In one embodiment, the diameter of the pulsed laser beam 6 is larger than the diameter of the continuous laser beam 7.

[0060] Based on the above embodiments, the present invention has conducted experiments on thin plate workpieces of different materials.

[0061] Experiment 1

[0062] S1. Select a 1.5-mm-thick TC4 titanium alloy thin plate as the workpiece 4, preprocess the workpiece 4 to be welded, and then fix the workpiece 4 to be welded on the fixed seat 3;

[0063] S2. Adjust the axial directions of the continuous laser beam 7 and the pulsed laser beam 6 to coaxially couple the continuous laser beam 7 and the pulsed laser beam 6 into a composite laser beam. Adjust the spraying direction of the shielding gas nozzle 2 so that the sprayed molten pool shielding gas is aligned with the molten pool. Adjust the release directions of the trailing shield 5 and the exhaust pipe 302 so that the released heating zone protective gas covers the weld seam and the area where the temperature rises on the side of the weld seam;

[0064] S3. Adjust the composite laser beam and control the spot diameter d of the composite laser beam irradiated on the molten pool to be 1.6 mm;

[0065] S4. Set the average output power P1 of the continuous laser to 1600 W, the defocus amount Δz1 of the continuous laser to +4 mm, set the average output power P2 of the pulsed laser to 300 W, the defocus amount Δz2 of the pulsed laser to +4 mm, the pulsed laser frequency f to 25 Hz, and the pulsed laser pulse width τ to 6 ms;

[0066] S5. Before welding, introduce the protective gas in the heating zone for 90 s to exhaust the air in the drag shield 5 and the exhaust pipe 302, so that the protective gas can fully protect the weld seam and prevent the weld seam from oxidation. Weld at a welding speed v of 1000 mm per minute. During the welding process, the coaxial double-beam laser head 1, the protective gas nozzle 2 and the drag shield 5 move synchronously. After welding, continue to introduce the protective gas for 90 s to protect the weld seam.

[0067] The surface of the TC4 titanium alloy weld seam obtained by using this method has good forming and a large depth-width ratio. After testing, the tensile strength can reach 948 Mpa, accounting for 92.3% of the base metal, and the deformation angle is controlled within 0.9°.

[0068] Experiment Two

[0069] S1. Select a 1.0-mm-thick 301 stainless steel thin plate as the workpiece 4, preprocess the workpiece 4 to be welded, and then fix the workpiece 4 to be welded on the fixing seat 3.

[0070] S2. Adjust the axial directions of the continuous laser beam 7 and the pulsed laser beam 6 to coaxially couple the continuous laser beam 7 and the pulsed laser beam 6 into a composite laser beam. Adjust the spraying direction of the protective gas nozzle 2 so that the sprayed molten pool protective gas is aligned with the molten pool.

[0071] S3. Adjust the composite laser beam and control the spot diameter d of the composite laser beam irradiated on the molten pool to be 1.8 mm. Before welding, introduce the protective gas in the heating zone for 90 s to exhaust the air in the drag shield and the copper tube, so that the protective gas can fully protect the weld seam and prevent the weld seam from oxidation.

[0072] S4. Set the average output power P1 of the continuous laser to 1700 W, the defocus amount Δz1 of the continuous laser to +5 mm, set the average output power P2 of the pulsed laser to 480 W, the defocus amount Δz2 of the pulsed laser to +5 mm, the pulsed laser frequency f to 25 Hz, and the pulsed laser pulse width τ to 6 ms.

[0073] S5. Weld at a welding speed v of 1000 mm per minute. During the welding process, the coaxial double-beam laser head 1 and the protective gas nozzle 2 move synchronously. After welding.

[0074] The surface of the 301 stainless steel weld seam obtained by using this method has good forming and a small heat affected zone. After testing, the tensile strength can reach 1000 Mpa, accounting for 72.5% of the base metal, and the deformation angle is controlled within 1°.

[0075] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0076] Specific examples are used in the present invention to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, there will be changes in the specific implementation manners and application scopes according to the idea of the present invention. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A coaxial dual-beam welding method, characterized in that: It includes the following steps: S1. Preprocess the workpiece to be welded, and then fix the workpiece to be welded; S2. Adjust the axial directions of the continuous laser beam (7) and the pulsed laser beam (6) so that the continuous laser beam (7) and the pulsed laser beam (6) are coaxially coupled into a composite laser beam, and adjust the spraying direction of the molten pool shielding gas so that the sprayed molten pool shielding gas is aligned with the molten pool; S3. Adjust the composite laser beam and control the spot diameter d of the composite laser beam irradiated on the molten pool; S4. Set the average output power of the continuous laser as P1, the defocus amount of the continuous laser as Δz1, set the average output power of the pulsed laser as P2, the defocus amount of the pulsed laser as Δz2, the pulsed laser frequency as f, and the pulsed laser pulse width as τ; S5. Weld at the welding speed ν, and at the same time spray the molten pool shielding gas onto the molten pool until the welding is completed.

2. The coaxial dual-beam welding method according to claim 1, wherein: In step S2, it also includes adjusting the release direction of the heating zone shielding gas so that the released heating zone shielding gas covers the weld and the area where the temperature rises on the side of the weld; In step S5, before starting welding, release the heating zone shielding gas, and the release time is t1. After the welding is completed, continuously release the heating zone shielding gas, and the release time is t2.

3. The coaxial dual-beam welding method according to claim 1, wherein: In step S2, the flow rate of the molten pool shielding gas is 10 to 30 liters per minute, and the flow rate of the heating zone shielding gas is 25 to 40 liters per minute.

4. The coaxial dual-beam welding method according to claim 1, characterized in that: In step S3, the value range of the diameter d of the composite laser beam is 1.0 mm to 4.0 mm.

5. The coaxial dual-beam welding method according to claim 1, characterized in that: In step S4, the value range of the average output power P1 of the continuous laser is 1400 W to 1800 W, the value range of the average output power P2 of the pulsed laser is 200 W to 500 W, and the ratio A of P1 to P2 is 2.5 ≤ A ≤ 5.

5. The value range of the defocus amount Δz1 of the continuous laser is +2 mm to +10 mm, the value range of the defocus amount Δz2 of the pulsed laser is +1 mm to +12 mm, and the ratio B of Δz1 to Δz2 is 0.5 ≤ B ≤ 2.

5.

6. The coaxial dual-beam welding method according to claim 1, characterized in that: In step S4, the value range of the pulsed laser frequency f is 10 Hz to 100 Hz, and the value range of the pulsed laser pulse width τ is 2 ms to 8 ms.

7. The coaxial dual-beam welding method according to claim 1, characterized in that: The value range of the welding speed ν is 700 mm per minute to 1500 mm per minute.

8. A coaxial dual-beam welding device, characterized in that: Applied to the coaxial double-beam welding method described in any one of claims 1 to 7, it includes a coaxial double-beam laser head (1), a shielding gas nozzle (2) for spraying the molten pool shielding gas, and a fixing seat (3) for fixing the workpiece (4); The fixing seat (3) includes a workpiece fixing surface, and a fixer (301) is arranged on the workpiece fixing surface. The workpiece (4) is fixed on the workpiece fixing surface. The coaxial double-beam laser head (1) and the shielding gas nozzle (2) are arranged outside the workpiece (4). During welding, the coaxial double-beam laser head (1) and the shielding gas nozzle (2) move synchronously along the welding direction.

9. The coaxial dual-beam welding equipment according to claim 8, characterized in that: A drag shield (5) is arranged on the surface of the workpiece (4) and covers the weld. The side of the drag shield (5) facing the workpiece (4) is provided with heating zone shielding gas release holes. During welding, the drag shield (5) moves synchronously with the coaxial double-beam laser head (1) along the welding direction; An exhaust pipe (302) for providing protective gas in the heating zone is arranged in the fixed seat (3), and vent holes for releasing the protective gas in the heating zone are formed in the workpiece fixing surface.

10. The coaxial dual-beam welding device according to claim 8, characterized in that: A condenser lens (101) is arranged in the coaxial double-beam laser head (1), and the pulsed laser beam (6) and the continuous laser beam (7) are combined into a composite laser beam that passes through the condenser lens (101).

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