Wire powder coaxial welding device and method based on adjustable focal length annular swing laser

Abstract

The invention discloses a wire powder coaxial welding device and method based on adjustable focal length annular swing laser. The device comprises an annular swing laser system, a coaxial wire feeding system, a coaxial powder feeding system, a shielding gas system, a water cooling system, a manipulator and a control system. The welding wire and the powder are melted by adjusting the laser power and the focal length through the annular swinging laser system; by adjusting the swing frequency, powder in a molten pool is promoted to be evenly mixed with components of the welding wire, grains are refined through the stirring effect of light beam swing, and the performance of a to-be-welded part is improved; the swing radius is adjusted to adapt to welding seams of different sizes; all the parameters are matched with the wire feeding speed and the powder feeding speed, so that accurate regulation and control of the center welding wire and the powder deposition amount are achieved, and different areas of the to-be-welded part are filled with welding layers with different components; compared with a traditional laser spot molten pool, stirring is more uniform, crystal grains are refined, and heat affected zones are reduced; and the focal length is adjusted to adapt to precise welding of welding seams with different thicknesses and complex geometry.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding, and in particular relates to a silk-powder coaxial welding device and method based on an annular oscillating laser with adjustable focal length. Background Art

[0002] Laser welding technology has been widely used in aerospace, automobile manufacturing, pipeline welding and other fields due to its advantages such as high energy density, low heat-affected zone and high precision. However, in aerospace, automobile manufacturing and other fields, the welded structures often have complex geometric shapes and strict performance requirements. Traditional fixed-focus laser welding technology is difficult to achieve the control of weld depth, width and material composition uniformity. In addition, the energy distribution of a single laser beam is uneven, which can easily lead to an excessively large heat-affected zone in the welding area, thereby affecting the mechanical properties and microstructure of the welded joint. These problems seriously restrict the application of laser welding technology in high-strength connections of complex structures. Summary of the invention

[0003] In order to solve the above problems, the purpose of the present invention is to provide a silk powder coaxial welding device and method based on an adjustable focal length circular oscillating laser, which can achieve precise control of the welding process and improve welding quality and efficiency by adjusting the laser focal length, oscillation frequency and radius;

[0004] In order to achieve the above-mentioned purpose, the silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length provided by the present invention comprises an annular oscillating laser system, a coaxial wire feeding system, a coaxial powder feeding system, a protective gas system, a water cooling system, a manipulator and a control system; wherein, the annular oscillating laser system is used to generate an annular oscillating light spot with adjustable oscillation radius and oscillation frequency, and the two light spots move clockwise to form a double annular running track, comprising a laser, an optical fiber, a fixed bracket, a first mechanical arm rotating bracket, a second mechanical arm rotating bracket, a servo, an annular oscillating light beam path, a collimator, a first controllable galvanometer, a second controllable galvanometer, a single-sided reflector, a focusing lens and a protective lens; the fixed bracket is connected to the end of the manipulator; the two annular oscillating light beam paths are arranged in a V shape, and a protective gas inlet is provided in the middle; the interior of each annular oscillating light beam path is provided with a collimator, a first controllable galvanometer, a second controllable galvanometer, a single-sided reflector, a focusing lens and a protective lens from bottom to bottom. A galvanometer, a single-sided reflector, a focusing lens and a protective lens; the first mechanical arm rotating bracket comprises an electric rotating bracket, an inner mechanical arm, an outer mechanical arm and a rotating joint; the electric rotating bracket is arranged at the inner upper part of the fixed bracket, and the two sides are respectively connected to the inner end of an inner mechanical arm in a symmetrical manner, and the outer end of each inner mechanical arm is connected to the inner end of an outer mechanical arm through a rotating joint; a steering gear is installed at the outer end of each outer mechanical arm, and the output end of each steering gear is connected to the middle upper part of a circular swinging light beam path; the second mechanical arm rotating bracket has the same structure as the first mechanical arm rotating bracket, wherein the electric rotating bracket is arranged at the inner lower part of the fixed bracket, a steering gear is installed at the outer end of each outer mechanical arm, and the output end of each steering gear is connected to the middle part of a circular swinging light beam path; the upper end of each optical fiber is connected to a laser, and the lower end is located above the collimator in a circular swinging light beam path;

[0005] The coaxial wire feeding system comprises a wire feeder, a wire feeding passage, a first adjustable collimator and a second adjustable collimator; wherein the wire feeding passage is vertically arranged, the upper part of which penetrates through the middle of the fixed bracket and the two electric rotating supports, the middle and lower sides of which are respectively provided with a first adjustable limit hole and a second adjustable limit hole, and the lower end is located between the annular swinging beam passage; the welding wire is arranged on the wire feeder in a coiled shape, and is straightened by the first adjustable collimator and the second adjustable collimator and then transported to the wire feeding passage, during which the welding wire passes through the first adjustable limit hole and the second adjustable limit hole to ensure that the welding wire passes through the wire feeding passage in a straight line, and finally reaches the workpiece to be welded;

[0006] The coaxial powder feeding system comprises an adjustable angle powder feeding passage, an electric rotatable bracket, a powder feeder and a powder feeding tube; the two adjustable angle powder feeding passages are arranged in a V shape between the two annular swinging light beam passages and the wire feeding passage; the powder feeder is connected to the upper ends of the two adjustable angle powder feeding passages through the powder feeding tube, and is used to feed the prepared powder in the powder tube into the adjustable angle powder feeding passage; the middle part of the electric rotatable bracket is sleeved on the outer side of the lower part of the wire feeding passage, and the two ends are respectively connected to the upper parts of the two adjustable angle powder feeding passages;

[0007] The shielding gas system comprises an argon gas bottle and an air supply pipe; wherein the upper end gas outlet of the argon gas bottle is connected to two shielding gas inlets through the air supply pipe, and the argon gas in the argon gas bottle enters into two circular swinging light beam paths through the air supply pipe and the shielding gas inlets, so as to prevent flying powder from contaminating the lens in the circular swinging laser system and prevent metal oxidation and contamination during welding;

[0008] The water cooling system includes a water cooling device, a water cooling machine and a water pipe; the water cooling device is detachably mounted on the lower outer side of the two annular swing beam passages, the wire feeding passage and the two adjustable angle powder feeding passages, and a water inlet and a water outlet are arranged at the upper end; the water cooling machine is connected to the water inlet and the water outlet through a water pipe, and performs cooling circulation in a closed loop, thereby ensuring temperature stability during long-term laser operation;

[0009] The control system is electrically connected to the steering gear, the first controllable galvanometer, the second controllable galvanometer, the single-sided reflector, the electric rotating support, the manipulator, the wire feeder, the electric rotatable support, the powder feeder, the control valve of the argon gas bottle, the water cooler and the laser.

[0010] The movement trajectories of the first controllable galvanometer and the second controllable galvanometer are perpendicular to each other and are used to collaboratively generate a light spot in a ring-shaped oscillating light beam.

[0011] The setting angle of the single-sided reflector is adjustable, and is used to adjust the laser emission path.

[0012] The manipulator adopts a manipulator with six degrees of freedom or more.

[0013] The protective gas system also includes a pressure gauge installed at the upper gas outlet of the argon gas bottle, which is used to adjust the pressure of the argon gas.

[0014] The apertures of the first adjustable limiting hole and the second adjustable limiting hole are adjustable to be suitable for welding wires with different diameters.

[0015] The welding method using the above-mentioned silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length includes the following steps performed in sequence:

[0016] 1. The staff will dry the required powder and place it in the powder barrel on the powder feeder;

[0017] 2. Use a laser cleaning machine to remove oxides and impurities on the surface of the workpiece to be welded and pre-treat it, and then place the part to be welded on it under the lower port of two adjustable angle powder feeding passages, two annular swinging beam passages and the wire feeding passage;

[0018] 3. Fix the fixed bracket on the manipulator with six degrees of freedom or more; under the control of the control system, according to the actual working conditions, use two electric rotating supports to adjust the angle between the two circular swinging beam paths so that the two circular swinging beam paths can work normally; then, according to the practical needs of the material to be welded, adjust the laser focal length in a larger range by adjusting the two rotating joints to adapt to different welding modes and the absorption of laser by different materials, so as to effectively avoid waste and pollution caused by material gasification; then use two servos to accurately adjust the centering of the laser beam, welding wire and powder to ensure that the laser beam, welding wire and powder are accurately focused on one point to achieve precise welding, thereby improving the utilization rate of welding wire and powder;

[0019] 4. Rotate the two adjustable angle metal powder delivery tubes to positions that are compatible with the two circular swinging beam paths through the rotatable bracket, and adjust the angles of the adjustable angle metal powder delivery tubes to match the adjusted laser focal length;

[0020] 5. Open the argon gas bottle and adjust the pressure gauge to allow the argon gas in the argon gas bottle to enter the two circular swinging beam paths through the gas supply pipe and the protective gas inlet to prevent the flying powder from contaminating the lenses in the circular swinging beam paths and prevent oxidation and contamination of the welded parts during the welding process;

[0021] 6. Turn on the powder feeder to allow the powder in the powder barrel to enter the adjustable angle powder feeding passage from the powder feeding pipe;

[0022] 7. Turn on the wire feeder to feed the welding wire, and then the welding wire is straightened by the first adjustable collimator and the second adjustable collimator and then fed into the wire feeding passage, during which the welding wire passes through the first adjustable limit hole and the second adjustable limit hole to ensure that the welding wire passes through the wire feeding passage in a straight line and finally reaches the workpiece to be welded;

[0023] 8. Turn on the water cooler to allow cooling water to enter the water cooling device through the water pipe and the water inlet. Use the water cooling device to cool the lower part of the annular swing beam passage, the wire feeding passage and the adjustable angle powder feeding passage, and then flow back to the water cooler through the water outlet and the water pipe to form a circulating cooling passage.

[0024] 9. Turn on the laser to emit a laser beam. After passing through the optical fiber, the laser beam passes through the collimating mirror, the first controllable galvanometer, the second controllable galvanometer, the one-sided reflector, the focusing lens and the protective lens in the annular swinging beam path in sequence, and then is emitted from the lower port of the annular swinging beam path to form an annular swinging beam, thereby melting the welding wire and powder, thereby performing wire-powder mixed welding on the welding position to be welded to form welding layers with different compositions.

[0025] The present invention has the following beneficial effects:

[0026] The laser power and focal length are adjusted by the circular oscillating laser system to melt the welding wire and powder; the oscillation frequency is adjusted to promote the uniform mixing of the powder and welding wire in the molten pool, and the stirring effect of the beam oscillation is used to refine the grains and improve the performance of the welded parts; the oscillation radius is adjusted to adapt to welds of different sizes; all the above parameters are matched with the wire feeding speed and powder feeding speed to achieve precise control of the central welding wire and powder deposition amount, so as to fill welding layers with different components in different areas of the welded parts; compared with the traditional laser spot, the molten pool is stirred more evenly, the grains are refined, and the heat-affected zone is reduced; the focal length is adjusted to adapt to the precise welding of welds of different thicknesses and complex geometries; the coaxial wire feeding and powder feeding technology is used to ensure the synchronous delivery of welding wire and powder, making it more stable and accurate. Combined with the multi-mode welding function, it can improve welding efficiency and reduce material waste. The device adopts an integrated design, integrating laser control, wire feeding, powder feeding, shielding gas and water cooling systems, simplifying the structure and enhancing reliability. It is suitable for complex structural welding of various materials such as aluminum alloy and stainless steel. In addition, the closed-loop water cooling and inert gas protection system take into account both equipment stability and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A partial structural schematic diagram of a silk-powder coaxial welding device based on an annular oscillating laser with adjustable focal length provided by the present invention;

[0028] Figure 2 A schematic diagram of the silk-powder coaxial welding device based on an annular oscillating laser with adjustable focal length provided by the present invention. DETAILED DESCRIPTION

[0029] The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 , Figure 2As shown, the silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length provided by the present invention comprises an annular oscillating laser system, a coaxial wire feeding system, a coaxial powder feeding system, a protective gas system, a water cooling system, a manipulator and a control system 71; wherein, the annular oscillating laser system is used to generate an annular oscillating light spot 28 with adjustable oscillation radius and oscillation frequency, and the two light spots move clockwise to form a double annular running track 29, comprising a laser 73, an optical fiber 74, a fixed bracket 11, a first mechanical arm rotating bracket 12, a second mechanical arm rotating bracket 13, a servo 16, an annular oscillating light beam path 18, a collimator 22, a first controllable galvanometer 23, a second controllable galvanometer 24, a single-sided reflector 25, a focusing lens 26 and a protective lens 27; the fixed bracket 11 is connected to the end of the manipulator; the two annular oscillating light beam paths 18 are arranged in a V shape, and a protective gas inlet 51 is provided in the middle; the interior of each annular oscillating light beam path 18 is provided with a collimator 22, a first controllable galvanometer 23, a second controllable galvanometer 24, a single-sided reflector 25, a focusing lens 26 and a protective lens 27 from bottom to bottom. 24, a single-sided reflector 25, a focusing lens 26 and a protective lens 27; the first mechanical arm rotating bracket 12 includes an electric rotating bracket, an inner mechanical arm, an outer mechanical arm and a rotating joint 14; the electric rotating bracket is arranged at the inner upper part of the fixed bracket 11, and the two sides are respectively connected to the inner end of an inner mechanical arm in a symmetrical manner, and the outer end of each inner mechanical arm is connected to the inner end of an outer mechanical arm through a rotating joint 14; a steering gear 16 is installed at the outer end of each outer mechanical arm, and the output end of each steering gear 16 is connected to the middle upper part of an annular swing beam path 18; the second mechanical arm rotating bracket 13 has the same structure as the first mechanical arm rotating bracket 12, wherein the electric rotating bracket is arranged at the inner lower part of the fixed bracket 11, a steering gear 16 is installed at the outer end of each outer mechanical arm, and the output end of each steering gear 16 is connected to the middle part of an annular swing beam path 18; the upper end of each optical fiber 74 is connected to a laser 73, and the lower end is located above the collimator 22 in an annular swing beam path 18;

[0031] The coaxial wire feeding system comprises a wire feeder 35, a wire feeding passage 32, a first adjustable collimator 37 and a second adjustable collimator 38; wherein the wire feeding passage 32 is vertically arranged, and the upper part thereof penetrates through the middle of the fixed bracket 11 and the two electric rotating supports, and the middle and lower sides thereof are respectively provided with a first adjustable limiting hole 33 and a second adjustable limiting hole 34, and the lower end thereof is located between the annular swinging beam passage 18; the welding wire 36 is arranged in a coil on the wire feeder 35, and is straightened by the first adjustable collimator 37 and the second adjustable collimator 38 and then transported to the wire feeding passage 32, during which the welding wire 36 passes through the first adjustable limiting hole 33 and the second adjustable limiting hole 34, so as to ensure that the welding wire 36 passes through the wire feeding passage 32 in a straight line; and finally reaches the workpiece 55 to be welded;

[0032] The coaxial powder feeding system comprises an adjustable angle powder feeding passage 41, an electric rotatable bracket 42, a powder feeder 43 and a powder feeding tube 45; the two adjustable angle powder feeding passages 41 are arranged in a V shape between the two annular swinging beam passages 18 and the wire feeding passage 32; the powder feeder 43 is connected to the upper ends of the two adjustable angle powder feeding passages 41 through the powder feeding tube 45, and is used to feed the prepared powder in the powder tube 44 into the adjustable angle powder feeding passage 41; the middle part of the electric rotatable bracket 42 is sleeved on the outer side of the lower part of the wire feeding passage 32, and the two ends are respectively connected to the upper parts of the two adjustable angle powder feeding passages 41;

[0033] The shielding gas system includes an argon gas bottle 52 and an air supply pipe 54; wherein the upper end gas outlet of the argon gas bottle 52 is connected to two shielding gas inlets 51 through the air supply pipe 54, and the argon gas in the argon gas bottle 52 enters the two circular oscillating beam paths 18 through the air supply pipe 54 and the shielding gas inlets 51, so as to prevent the flying powder from contaminating the lens in the circular oscillating laser system, and at the same time prevent the metal from being oxidized and contaminated during the welding process;

[0034] The water cooling system includes a water cooling device 63, a water cooling machine 64 and a water pipe 65; the water cooling device 63 is detachably mounted on the lower outer side of the two annular swinging beam passages 18, the wire feeding passage 32 and the two adjustable angle powder feeding passages 41, and a water inlet 61 and a water outlet 62 are provided at the upper end; the water cooling machine 64 is connected to the water inlet 61 and the water outlet 62 through the water pipe 65, and performs cooling circulation in a closed loop, thereby ensuring temperature stability during long-term laser operation;

[0035] The control system 71 is electrically connected to the steering gear 16, the first controllable galvanometer 23, the second controllable galvanometer 24, the single-sided reflector 25, the electric rotating support, the manipulator, the wire feeder 35, the electric rotatable bracket 42, the powder feeder 43, the control valve of the argon gas bottle 52, the water cooler 64 and the laser 73 respectively.

[0036] The movement trajectories of the first controllable galvanometer 23 and the second controllable galvanometer 24 are perpendicular to each other, and are used to collaboratively generate the light spot in the annular oscillating light beam 28 .

[0037] The setting angle of the single-sided reflector 25 is adjustable, and is used to adjust the laser emission path.

[0038] The manipulator adopts a manipulator with six degrees of freedom or more.

[0039] The protective gas system further comprises a pressure gauge 53 installed at the gas outlet at the upper end of the argon gas bottle 52 for adjusting the pressure of the argon gas.

[0040] The apertures of the first adjustable limiting hole 33 and the second adjustable limiting hole 34 are adjustable to be suitable for welding wires 36 of different diameters.

[0041] The welding method using the above-mentioned silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length includes the following steps performed in sequence:

[0042] 1. The staff dries the required powder and places it in the powder cylinder 44 on the powder feeder 43;

[0043] 2. Use a laser cleaning machine to remove oxides and impurities on the surface of the workpiece 55 to pre-treat it, and then place the part to be welded on it below the lower ports of the two adjustable angle powder feeding passages 41, the two annular swinging beam passages 18 and the wire feeding passage 32;

[0044] 3. Fix the fixed bracket 11 on a manipulator with six degrees of freedom or more; under the control of the control system 71, according to the actual working conditions, use two electric rotating supports to adjust the angle between the two annular swinging beam paths 18 so that the two annular swinging beam paths 18 can work normally; then, according to the practical needs of the material of the welded part 55, adjust the laser focal length in a larger range by adjusting the two rotating joints 14 to adapt to different welding modes and to adapt to the absorption of laser by different materials, so as to effectively avoid waste and pollution caused by material gasification; then use two steering gears 16 to accurately adjust the centering of the laser beam, the welding wire 36, and the powder to ensure that the laser beam, the welding wire 36, and the powder are accurately focused on one point to achieve accurate welding, thereby improving the utilization rate of the welding wire 36 and the powder;

[0045] 4. Rotate the two adjustable angle metal powder delivery tubes 41 to positions that are compatible with the two annular swinging beam paths 18 through the rotatable bracket 42, and adjust the angles of the adjustable angle metal powder delivery tubes 41 to match the adjusted laser focal length;

[0046] 5. Open the argon gas bottle 52 and adjust the pressure gauge 53 so that the argon gas in the argon gas bottle 52 enters the two annular swing beam paths 18 through the gas delivery pipe 54 and the protective gas inlet 51 to prevent the flying powder from contaminating the lenses in the annular swing beam paths 18 and prevent oxidation and contamination of the welded parts 55 during the welding process;

[0047] 6. Turn on the powder feeder 43 to allow the powder in the powder tube 44 to enter the angle-adjustable powder feeding passage 41 from the powder feeding pipe 45;

[0048] 7. Turn on the wire feeder 35, thereby feeding the welding wire 36, and then the welding wire 36 is straightened by the first adjustable collimator 37 and the second adjustable collimator 38 and then fed into the wire feeding passage 32, during which the welding wire 36 passes through the first adjustable limiting hole 33 and the second adjustable limiting hole 34, so as to ensure that the welding wire 36 passes through the wire feeding passage 32 in a straight line and finally reaches the workpiece 55 to be welded;

[0049] 8. Turn on the water cooler 64, so that cooling water enters the water cooling device 63 through the water pipe 65 and the water inlet 61, and uses the water cooling device 63 to cool the lower part of the annular swinging beam passage 18, the wire feeding passage (32) and the adjustable angle powder feeding passage 41, and then flows back to the water cooler 64 through the water outlet 62 and the water pipe 65, forming a circulating cooling passage;

[0050] 9. Turn on the laser 73 to emit a laser beam. After passing through the optical fiber 74, the laser beam passes through the collimating mirror 22, the first controllable galvanometer 23, the second controllable galvanometer 24, the one-sided reflector 25, the focusing lens 26 and the protective lens 27 in the annular swinging beam path 18 in sequence, and then is emitted from the lower port of the annular swinging beam path 18 to form an annular swinging beam 28, thereby melting the welding wire 36 and the powder, so as to perform wire-powder mixed welding on the welding position to be welded to form welding layers with different compositions.

[0051] In addition, the silk-powder coaxial welding device based on an adjustable focal length circular oscillating laser provided by the present invention has multiple working modes, including single laser welding, multi-laser collaborative welding, light-silk-powder (multi-channel, single-channel) welding, light-silk welding and light-powder (multi-channel, single-channel) welding, so the appropriate welding mode can be selected according to needs.

[0052] The present invention is further described below by specific examples;

[0053] Embodiment 1:

[0054] In this embodiment, the welded part 55 is made of a stainless steel plate of 120mm*240mm*2mm, the welding wire is a stainless steel welding wire with a diameter of 1mm, and the shielding gas is argon;

[0055] Perform laser path planning according to the comprehensive performance and size requirements of the welded part 55;

[0056] According to the required composition and mechanical properties of the welded parts, the wire powder feeding speed is designed, and the appropriate swing radius and swing frequency are matched; the welding gap is between 0-1mm, the gap height difference is between 0-0.5mm, and the welded part needs to have good strength and plasticity. The welding parameters are: laser power 1000W, wire feeding speed 32mm / s, laser moving speed 20mm / s, swing radius 2mm, and swing frequency 40Hz;

[0057] Embodiment 2:

[0058] The welded part 55 in this embodiment is made of 100mm*100mm*2mm A3 steel plate, the welding wire is a stainless steel welding wire with a diameter of 0.5mm, and the powder is Fe-J-3 powder with nano-tungsten carbide added;

[0059] According to the required composition and mechanical properties of the welded parts, the wire powder feeding speed is designed, and the appropriate swing radius and swing frequency are matched; the welding gap is between 0-1mm, the gap height difference is between 0-0.5mm, and the welded part needs to have good strength and plasticity. The welding parameters are: laser power 1200W, wire feeding speed 16mm / s, powder feeding speed 0.4g / min, laser moving speed 20mm / s, swing radius 2mm, and swing frequency 30Hz;

[0060] In addition, in this embodiment, the welding powder can be mixed with nanometer or nano-ceramic particles according to different performance requirements; and the laser focal length can be adjusted according to the matching ratio of welding wire and powder.

Claims

1. A silk-powder coaxial welding device based on an adjustable focal length circular oscillating laser, characterized in that: The wire-powder coaxial welding device comprises a circular oscillating laser system, a coaxial wire feeding system, a coaxial powder feeding system, a protective gas system, a water cooling system, a manipulator and a control system (71); wherein the circular oscillating laser system is used to generate a circular oscillating light spot (28) with an adjustable oscillation radius and oscillation frequency, and the two light spots move clockwise to form a double circular running track (29), and comprises a laser (73), an optical fiber (74), a fixed bracket (11), a first mechanical arm rotating bracket (12), a second mechanical arm rotating bracket (13), a steering gear (16), ... The invention relates to a mechanical arm comprising a plurality of ring-shaped swing beam paths (18), a collimator mirror (22), a first controllable galvanometer mirror (23), a second controllable galvanometer mirror (24), a single-sided reflector (25), a focusing lens (26) and a protective lens (27); a fixed bracket (11) is connected to the end of the manipulator; two ring-shaped swing beam paths (18) are arranged in a V shape, and a protective gas inlet (51) is provided in the middle; and the collimator mirror (22), a first controllable galvanometer mirror (23), a second controllable galvanometer mirror (24), a single-sided reflector (25), a focusing lens (26) and a protective lens (27) are provided in each ring-shaped swing beam path (18) from bottom to bottom. mirror (25), a focusing lens (26) and a protective lens (27); the first mechanical arm rotating bracket (12) comprises an electric rotating support, an inner mechanical arm, an outer mechanical arm and a rotating joint (14); the electric rotating support is arranged at the inner upper part of the fixed bracket (11), and the two sides are respectively connected to the inner end of an inner mechanical arm in a symmetrical manner, and the outer end of each inner mechanical arm is connected to the inner end of an outer mechanical arm through a rotating joint (14); a steering gear (16) is installed at the outer end of each outer mechanical arm, and the output end of each steering gear (16) is connected to The second mechanical arm rotating bracket (13) has the same structure as the first mechanical arm rotating bracket (12), wherein the electric rotating support is arranged at the inner lower part of the fixed bracket (11), a steering gear (16) is installed at the outer end of each outer mechanical arm, and the output end of each steering gear (16) is connected to the middle part of the circular swinging light beam path (18); the upper end of each optical fiber (74) is connected to a laser (73), and the lower end is located above the collimator (22) in the circular swinging light beam path (18); The coaxial wire feeding system comprises a wire feeder (35), a wire feeding passage (32), a first adjustable collimator (37) and a second adjustable collimator (38); wherein the wire feeding passage (32) is arranged vertically, the upper part of which penetrates through the middle of the fixed bracket (11) and the two electric rotating supports, the middle and lower sides of which are respectively provided with a first adjustable limit hole (33) and a second adjustable limit hole (34), and the lower end of which is located between the annular swinging beam passage (18); the welding wire (36) is arranged in a coil on the wire feeder (35), and is straightened by the first adjustable collimator (37) and the second adjustable collimator (38) and then transported to the wire feeding passage (32), during which it passes through the first adjustable limit hole (33) and the second adjustable limit hole (34); The coaxial powder feeding system comprises an adjustable angle powder feeding passage (41), an electrically rotatable support (42), a powder feeder (43) and a powder feeding pipe (45); the two adjustable angle powder feeding passages (41) are arranged in a V shape between the two annular swinging light beam passages (18) and the wire feeding passage (32); the powder feeder (43) is connected to the upper ends of the two adjustable angle powder feeding passages (41) through the powder feeding pipe (45) and is used to feed the prepared powder in the powder barrel (44) into the adjustable angle powder feeding passage (41); the middle part of the electrically rotatable support (42) is sleeved on the outer side of the lower part of the wire feeding passage (32), and the two ends are respectively connected to the upper parts of the two adjustable angle powder feeding passages (41); The protective gas system comprises an argon gas bottle (52) and an air supply pipe (54); wherein the upper gas outlet of the argon gas bottle (52) is connected to two protective gas inlets (51) via the air supply pipe (54); The water cooling system comprises a water cooling device (63), a water cooling machine (64) and a water pipe (65); the water cooling device (63) is detachably mounted on the lower outer sides of the two annular swinging light beam passages (18), the wire feeding passage (32) and the two adjustable angle powder feeding passages (41), and is provided with a water inlet (61) and a water outlet (62) at the upper end; the water cooling machine (64) is connected to the water inlet (61) and the water outlet (62) via a water pipe (65); The control system (71) is electrically connected to the steering gear (16), the first controllable galvanometer (23), the second controllable galvanometer (24), the single-sided reflector (25), the electric rotating support, the manipulator, the wire feeder (35), the electric rotatable bracket (42), the powder feeder (43), the control valve of the argon gas bottle (52), the water cooler (64) and the laser (73).

2. The silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length according to claim 1 is characterized in that: The movement trajectories of the first controllable galvanometer (23) and the second controllable galvanometer (24) are perpendicular to each other and are used to collaboratively generate a light spot in the annular oscillating light beam (28).

3. The silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length according to claim 1 is characterized in that: The setting angle of the single-sided reflector (25) is adjustable and is used to adjust the laser emission path.

4. The silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length according to claim 1 is characterized in that: The manipulator adopts a manipulator with six degrees of freedom or more.

5. The silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length according to claim 1, characterized in that: The protective gas system further comprises a pressure gauge (53) installed at the gas outlet at the upper end of the argon gas bottle (52) for adjusting the pressure of the argon gas.

6. The silk-powder coaxial welding device based on annular oscillating laser with adjustable focal length according to claim 1, characterized in that: The apertures of the first adjustable limiting hole (33) and the second adjustable limiting hole (34) are adjustable so as to be suitable for welding wires (36) of different diameters.

7. A welding method using the silk-powder coaxial welding device based on an adjustable focal length circular oscillating laser according to any one of claims 1 to 6, characterized in that: The welding method comprises the following steps performed in sequence: 1) A staff member dries the required powder and places it in a powder cylinder (44) on a powder feeder (43); 2) using a laser cleaning machine to remove oxides and impurities on the surface of the workpiece (55) to be welded and pre-treat it, and then placing the part to be welded on it below the lower ports of two adjustable angle powder feeding passages (41), two annular swinging beam passages (18) and a wire feeding passage (32); 3) Fixing the fixed support (11) on a manipulator with six degrees of freedom or more; under the control of the control system (71), using two electric rotating supports to adjust the angle between the two annular swinging beam paths (18) according to actual working conditions; then adjusting the laser focal length over a large range by adjusting the two rotating joints (14) according to the practical requirements of the material of the welded part (55); and then using two steering gears (16) to accurately adjust the centering of the laser beam, the welding wire (36) and the powder; 4) rotating the two adjustable angle metal powder delivery tubes (41) to positions adapted to the two annular swinging beam paths (18) through the rotatable bracket (42), and adjusting the angles of the adjustable angle metal powder delivery tubes (41) to match the adjusted laser focal length; 5) Open the argon gas bottle (52) and adjust the pressure gauge (53) so that the argon gas in the argon gas bottle (52) passes through the gas delivery pipe (54) and the protective gas inlet (51) into the two annular oscillating light beam paths (18); 6) Open the powder feeder (43) to allow the powder in the powder tube (44) to enter the angle-adjustable powder feeding passage (41) from the powder feeding pipe (45); 7) Turning on the wire feeder (35), thereby feeding out the welding wire (36), and then the welding wire (36) is straightened by the first adjustable collimator (37) and the second adjustable collimator (38) and then fed into the wire feeding passage (32), during which it passes through the first adjustable limiting hole (33) and the second adjustable limiting hole (34), and finally reaches the workpiece (55) to be welded; 8) Turn on the water cooler (64) to allow cooling water to enter the water cooling device (63) through the water pipe (65) and the water inlet (61), and use the water cooling device (63) to cool the lower part of the annular swinging beam passage (18), the wire feeding passage (32) and the adjustable angle powder feeding passage (41), and then flow back to the water cooler (64) through the water outlet (62) and the water pipe (65), forming a circulating cooling passage; 9) Turn on the laser (73) to emit a laser beam. After passing through the optical fiber (74), the laser beam passes through the collimating mirror (22), the first controllable galvanometer (23), the second controllable galvanometer (24), the one-sided reflector (25), the focusing lens (26) and the protective lens (27) in the annular oscillating beam path (18) in sequence, and then is emitted from the lower port of the annular oscillating beam path (18) to form an annular oscillating beam (28), thereby melting the welding wire (36) and the powder, thereby performing wire-powder mixed welding on the welding position to be welded to form a welding layer with different components.

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