7-series aluminum alloy composite light source laser welding method and system

Abstract

The invention discloses a 7-series aluminum alloy composite light source laser welding method, which is characterized in that stitch welding is carried out on double-layer 7-series aluminum alloy test pieces by using a composite light beam formed by a near-infrared laser beam and a blue laser beam, the thickness of the upper-layer 7-series aluminum alloy test piece is 1-2mm, and the thickness of the lower-layer 7-series aluminum alloy test piece is 2mm; before welding, removing an oxide layer on the surface of the aluminum alloy, then pressing up and down through a jig, and setting welding parameters and paths; during welding, light spots of a near-infrared laser beam and a blue laser beam are concentric and emitted at the same time, the two laser beams are coupled and focused to a swing welding head, and stitch welding is carried out according to set welding parameters and paths; the light spot diameter of the blue light laser beam is larger than that of the near-infrared laser beam. Near-infrared light and blue light form coaxial composite light spots and emit light at the same time, stitch welding is conducted on the double-layer aluminum alloy test piece in combination with the swing welding head, and the stitch welding device has the advantages of being high in welding efficiency, good in air hole state and few in splashing and cracks.

Description

Technical Field

[0001] The invention relates to the field of optical fiber laser technology, and in particular to a method for reducing internal defects of a 7 series aluminum alloy by welding with a composite light source. Background Art

[0002] 7 series aluminum alloy is a super high performance aluminum alloy with advantages such as low density and high strength. It is one of the main structural materials in the fields of aviation, aerospace, and transportation. However, its weldability is poor. Conventional arc welding methods are prone to defects such as thermal cracks and pores, which affect the performance and life of the welded joints. Laser welding technology is very suitable for the welding of 7 series aluminum alloys due to its high energy density characteristics, but defects such as pores and cracks will occur when laser welding is used alone, and single laser heat source welding has problems such as low energy utilization and low welding efficiency. Summary of the invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a 7-series aluminum alloy composite light source laser welding method and system, which forms a coaxial composite light spot through near-infrared and blue light and emits light at the same time, and combines a swing welding head to perform stack welding on double-layer aluminum alloy specimens, which has the advantages of high welding efficiency, good porosity state, and less spatter and cracks.

[0004] According to one aspect of the present invention, a composite light source laser welding method for 7 series aluminum alloy is provided, wherein a composite light beam formed by a near-infrared laser beam and a blue light laser beam is used to stack weld a double-layer 7 series aluminum alloy specimen, wherein the thickness of the upper layer 7 series aluminum alloy specimen is 1-2 mm, and the thickness of the lower layer 7 series aluminum alloy specimen is 2 mm; Before welding, remove the oxide layer on the surface of the aluminum alloy and press it up and down with a jig to set the welding parameters and path; During welding, the spots of the near-infrared laser beam and the blue laser beam are concentric and emitted simultaneously. The two laser beams are coupled and focused on the swing welding head, and the overlap welding is performed according to the set welding parameters and path. The spot diameter of the blue laser beam is larger than the spot diameter of the near-infrared laser beam.

[0005] As a further technical solution, after welding, the internal state of the weld is obtained through metallographic testing, and the crack length and pore area are measured through a digital microscope to obtain the welding effect.

[0006] As a further technical solution, the metallographic detection includes: cutting the welded parts after lap welding along the weld XYZ respectively, grinding and polishing with 80-5000 mesh sandpaper after cutting, mounting the sample with a mounting machine after grinding and polishing, and finally abrading with Keller reagent for a set time.

[0007] As a further technical solution, before welding, a nanosecond MOPA laser is used to remove the oxide layer, and a bow-shaped filling is set to scan the laser incident surface and the contact surface of the upper and lower aluminum alloy specimens.

[0008] As a further technical solution, among the welding parameters, the adjustable parameters include dual laser power, welding speed, welding head swing amplitude, welding head swing frequency and shielding gas flow rate.

[0009] As a further technical solution, before welding, the near-infrared laser power is set to 500-900W, the blue light laser power is set to 500W, the welding speed is set to 50-150mm / s, the welding head swing amplitude is set to 0.8mm, the welding head swing frequency is set to 100-300Hz, and the swing pattern is circular.

[0010] As a further technical solution, before welding, the processing path is planned and the moving path is controlled by coordinates, and the moving length is set to 20 mm.

[0011] As a further technical solution, during welding, the shielding gas is turned on and the shielding gas flow rate is adjusted to 20L / min.

[0012] As a further technical solution, the core diameter of the optical fiber of the near-infrared laser is 14um.

[0013] According to one aspect of the present invention, a 7-series aluminum alloy composite light source laser welding system is provided, comprising a near-infrared laser, a blue laser, an oscillating welding head and a fixture for pressing a double-layer 7-series aluminum alloy specimen, wherein the near-infrared laser and the blue laser simultaneously emit laser beams, the two laser beams are coupled and focused to the oscillating welding head, and the double-layer 7-series aluminum alloy specimen is overlap-welded according to set welding parameters and paths; wherein the thickness of the upper 7-series aluminum alloy specimen is 1-2 mm, and the thickness of the lower 7-series aluminum alloy specimen is 2 mm; the spots of the near-infrared laser beam and the blue laser beam are concentric, and the spot diameter of the blue laser beam is larger than the spot diameter of the near-infrared laser beam.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention arranges the near-infrared laser beam and the blue laser beam concentrically and emits light at the same time. The diameter of the blue light spot is larger than that of the near-infrared spot. Therefore, the low-power blue laser beam can heat the aluminum plate first, and then the high-temperature surface of the aluminum plate is irradiated by the high-power near-infrared laser beam to form deep small holes. Compared with the single laser welding method, the welding efficiency can be increased by 1.45 times.

[0015] The present invention takes into account that the absorption rate of aluminum alloy materials to infrared light is only 3%-5%, which can reach 30%-60% after melting. After forming a small hole and generating the Fresnel effect, the absorption rate can reach 90%. Therefore, the surface state of the aluminum alloy is very important to the laser absorption rate, and the absorption rate of aluminum alloy to blue light can reach more than 10%. When blue light is used as a composite light source, a molten state can appear on the surface of the material, thereby greatly improving the absorption rate of the aluminum alloy to near-infrared laser. Compared with the composite light beam of semiconductor laser and fiber laser, there is no need for high-power semiconductor laser to preheat (high-power laser preheating will cause the weld width to be too large), and a smaller laser power can also be used to meet the welding requirements, thereby reducing energy consumption and improving work efficiency.

[0016] The near-infrared laser beam and the blue light laser beam of the present invention are concentrically arranged and emit light at the same time, and the large-diameter spot of the blue light is used for preheating in advance, and no additional preheating time is required. Compared with the existing composite light beam welding method of first emitting light for preheating and then emitting light for welding, the welding efficiency is greatly improved.

[0017] The present invention selects a suitable fiber core diameter, power and wavelength of the near-infrared laser so that the welding laser has high energy density, small heat input and deformation, and is more suitable for aluminum alloy welding. At the same time, by setting the swing amplitude and frequency of the composite welding head and controlling the action time of the near-infrared laser beam and the aluminum alloy, the energy distribution of the weld is more uniform, which is more conducive to the discharge of pores.

[0018] The present invention achieves the effects of large melting depth and less spatter through the mutual coordination of dual laser power, welding speed, welding head swing amplitude and frequency, and shielding gas flow rate, and cracks only appear at the tail after welding.

[0019] After welding, the present invention performs metallographic detection in three directions, XYZ, and can obtain accurate welding effect data. Compared with the existing method of deducing welding effect through theory, the present invention can perform accurate welding effect evaluation, which is more conducive to engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic flow chart of a 7-series aluminum alloy composite light source laser welding method provided in an embodiment of the present invention.

[0022] Figure 2 A schematic diagram of a fixture provided in an embodiment of the present invention.

[0023] Figure 3 Schematic diagram of a 7 series aluminum alloy specimen provided in an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the appearance after welding provided by an embodiment of the present invention.

[0025] Figure 5 This is a metallographic diagram of single laser welding provided in an embodiment of the present invention.

[0026] Figure 6 This is a metallographic diagram of near-infrared blue light composite welding provided in an embodiment of the present invention.

[0027] Figure 7 (a)-(b) are comparison diagrams of optical fiber semiconductor composite welding and near-infrared blue light composite welding provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] The embodiment of the present invention provides a 7 series aluminum alloy composite light source laser welding method, such as Figure 1 As shown, a composite beam formed by a near-infrared laser beam and a blue laser beam is used to stack weld a double-layer 7 series aluminum alloy specimen, wherein the thickness of the upper 7 series aluminum alloy specimen is 1-2 mm, and the thickness of the lower 7 series aluminum alloy specimen is 2 mm; before welding, the surface oxide layer of the aluminum alloy is removed and then pressed up and down by a fixture, and welding parameters and paths are set; during welding, the spots of the near-infrared laser beam and the blue laser beam are concentric and emitted simultaneously, and the two laser beams are coupled and focused on the swing welding head, and stack welding is performed according to the set welding parameters and paths; the spot diameter of the blue laser beam is larger than the spot diameter of the near-infrared laser beam.

[0030] The purpose of the present invention is to provide a method for reducing internal defects after laser welding of 7 aluminum alloy, so as to overcome the problems existing in the related art to a certain extent. The method adopts a 1080±5nm infrared plus 430-470nm blue light composite light source and combines a composite welding head for welding. Compared with single laser welding, blue light can make the molten pool more stable, reduce spatter and internal cracks and pores during welding; compared with the existing double-beam composite welding, blue light does not need to be preheated in advance, which reduces energy loss and improves work efficiency. At the same time, the swing amplitude and frequency of the composite welding head can control the action time of the near-infrared laser and the aluminum alloy, so that the energy distribution is more uniform and the welding effect is better.

[0031] In the embodiment of the present invention, the adjustable process parameters include: dual laser power, welding speed, welding head swing amplitude, welding head swing speed (frequency) and shielding gas flow rate. In terms of laser light source selection, the present invention selects Gaussian near-infrared light with a core diameter of 14um (this core diameter laser has high energy density, small heat input and deformation, and has significant advantages for aluminum alloy welding) for deep fusion welding, and selects blue light for auxiliary heating, and the core diameter of the blue light is not limited. The near-infrared laser beam and the blue laser beam are coupled together via a composite swing welding head and incident on the welding position concentrically and synchronously.

[0032] Furthermore, the composite swing welding head controls the swing of the lens in the welding head through a motor so that the infrared beam forms a welding track, and then merges into the blue light beam. The composite infrared and blue light beams converge at one point through the focusing lens below. Among them, the swing amplitude and swing frequency can be set according to welding requirements. For example, the swing pattern, amplitude and frequency can be set through the control software, and an electrical signal can be output to the motor to trigger the motor to swing according to the set swing parameters.

[0033] Before welding, prepare near-infrared laser, blue light laser, composite oscillating welding head, jig and blowing device, etc. First, remove the surface curing layer of the aluminum alloy material, then fix the double-layer 7 series aluminum alloy specimen to be welded with the jig, set the relevant process parameters and processing path, and connect the protective gas.

[0034] During welding, the spots of the near-infrared laser beam and the blue laser beam are concentric and emit light at the same time. The two laser beams are coupled and focused on the swing welding head, and overlap welding is performed according to the set welding parameters (including laser parameters and swing parameters) and path.

[0035] After welding, metallographic examination is performed on the welded parts. After metallographic examination, the crack length and pore area are measured using a digital microscope to obtain accurate welding effect data in order to obtain a true welding effect evaluation.

[0036] Specifically, the metallographic detection may include: the first step is to cut along the weld XYZ respectively, the second step is to grind and polish with 80-5000 mesh sandpaper, the third step is to mount the sample with a mounting machine, and the fourth step is to abrade with Keller reagent for 15S.

[0037] It should be noted that, at present, the welding effect of dual-beam composite application on 7 series aluminum alloys tends to be derived theoretically, and lacks practical detection standards, which makes it difficult to obtain welding products with good consistency in engineering applications. For this reason, the present invention provides the above-mentioned metallographic detection and data measurement method, which is convenient for engineering personnel to detect and evaluate the welding effect, and provides a clear welding effect evaluation method, so as to obtain welding products with good consistency in actual engineering applications.

[0038] As a preferred embodiment, the present invention takes aluminum alloy 7075 with an upper layer thickness of 1 mm and a lower layer thickness of 2 mm as an example. Figure 3 As shown in the figure, a composite light source welding method for 7 series aluminum alloy is introduced. The devices involved include near-infrared laser, blue laser, composite swing welding head, fixture, air blowing device, etc. The adjustable process parameters include dual laser power, welding speed, welding head swing amplitude, welding head swing speed, shielding gas flow, etc. After the aluminum material is deoxidized, it is pressed up and down by the fixture, and the relevant parameters and paths are set for overlap welding. After the welding is completed, observe the internal cracks and pores to determine the effect.

[0039] The specific steps of this method are as follows: (1) Prepare the necessary equipment: the infrared laser wavelength is 1080nm and the core diameter is 14um; the blue laser wavelength is 450nm and the core diameter is 400um; the composite welding head infrared lens collimation is 150mm, the blue light collimation is 100mm, and the shared focus is 150mm; the near-infrared laser beam and the blue laser beam have concentric spots.

[0040] (2) Prepare materials and fixtures: Aluminum alloy 7075, upper layer thickness 1mm, lower layer thickness 2mm, design clamping fixtures, such as Figure 2 shown.

[0041] (3) Pre-treat the aluminum alloy plate: Use a nanosecond MOPA laser to remove the oxide layer. The laser wavelength is 1064nm and the power is 70W. Set the bow filling, the line spacing is 0.03mm, and the process parameters are set to 20% power, 200KHz frequency, and 100ns pulse width. During pre-treatment, scan the laser incident surface and the contact surface of the upper and lower materials once (the front and back of the upper material, the front of the lower material). Removing the oxide layer can reduce defects such as inclusions and pores inside the weld and improve the joint performance.

[0042] (4) Use a fixture to clamp the two plates together and set the process parameters: set the near-infrared laser power to 500-900W, set the blue light laser power to 500W, set the welding speed to 50-150mm / s, set the focus position to 0mm, the laser swing amplitude to 0.8mm, the laser swing frequency to 100-300Hz, and the swing pattern to a circle.

[0043] (5) Plan the processing path and control the moving path through coordinates: set the length to 20 mm.

[0044] (6) Connect the protective gas: adjust the protective gas argon flow rate to 20L / min.

[0045] (7) Metallographic examination: The first step is to cut along the weld XYZ respectively, the second step is to polish with 80-5000 mesh sandpaper, the third step is to mount the sample with a mounting machine, and the fourth step is to abrade with Keller reagent for 15S.

[0046] (8) Measurement data: Use a digital microscope to measure the crack length and pore area to confirm the effect, such as Figure 4 shown.

[0047] Figure 5 This is a single laser welding metallographic diagram. Figure 6 This is the metallographic diagram of the dual-light source composite welding of the present invention. Through data comparison, it can be obviously seen that the weld width of the present invention is smaller, the penetration depth is deeper, the porosity state is better, the cracks are fewer and there is almost no spatter.

[0048] Figure 7 The figure is a comparison diagram of optical fiber semiconductor composite welding and near infrared blue light welding. In figure (a), the crack length of optical fiber semiconductor composite welding is 1.52mm, and in figure (b), the crack length of near infrared blue light composite welding is 0.47mm. It can be seen that the method of the present invention has a better control effect on cracks. And because the crack appears at the tail, it is easy to eliminate it through other control methods, further improving the welding quality.

[0049] Based on the same inventive concept as the method embodiment, the present invention also provides a 7-series aluminum alloy composite light source laser welding system, including a near-infrared laser, a blue light laser, an oscillating welding head and a fixture for pressing a double-layer 7-series aluminum alloy specimen, the near-infrared laser and the blue light laser simultaneously emit laser beams, the two laser beams are coupled and focused to the oscillating welding head, and the double-layer 7-series aluminum alloy specimen is stacked according to the set welding parameters and paths; wherein the thickness of the upper 7-series aluminum alloy specimen is 1-2mm, and the thickness of the lower 7-series aluminum alloy specimen is 2mm; the spots of the near-infrared laser beam and the blue light laser beam are concentric, and the spot diameter of the blue light laser beam is larger than the spot diameter of the near-infrared laser beam.

[0050] When the system of the present invention is used for aluminum alloy stitch welding, the parameters such as the dual laser power, welding speed, welding head swing amplitude, welding head swing speed (frequency) and shielding gas flow rate are set before welding and the parameters are adjustable. Before welding, prepare the near-infrared laser, blue laser, composite swing welding head, fixture and blowing device, etc., first remove the surface nutrient layer of the aluminum alloy material, then fix the double-layer 7 series aluminum alloy specimen to be welded by the fixture, set the relevant process parameters and processing path, and connect the shielding gas. During welding, the light spots of the near-infrared laser beam and the blue laser beam are concentric and emit light at the same time. The two laser beams are coupled and focused on the swing welding head, and stitch welding is performed according to the set welding parameters (including laser parameters and swing parameters) and paths. After welding, the welded parts are subjected to metallographic inspection, and after the metallographic inspection, the crack length and pore area are measured using a digital microscope to obtain accurate welding effect data to obtain a true welding effect evaluation.

[0051] In summary, compared with single laser welding, the present invention has the following advantages: 1. The present invention emits the near-infrared laser beam and the blue laser beam concentrically and simultaneously to form a composite beam, in which the blue light spot diameter is larger. The low-power blue laser can heat the aluminum plate first, and then the high-temperature surface of the aluminum plate is irradiated by the high-power infrared laser to form deep small holes. The efficiency of this composite laser welding is 1.45 times higher than that of a single laser.

[0052] 2. At the same welding speed, the penetration depth of near-infrared blue light composite welding is deeper. When the welding speed is reduced, the penetration depth can reach more than 3 times that of single fiber welding, and the porosity state is better.

[0053] 3. The present invention makes the near-infrared blue light composite beam have good welding performance, stabilize the molten pool, and almost no spatter by properly matching the fiber core diameter, power, and wavelength of the two lasers and coaxially and synchronously emitting light. Specifically, by further expanding the molten pool and the small hole, the internal heat convection is stabilized, thereby reducing or even eliminating the generation of spatter.

[0054] 4. Compared with the random cracks produced by single laser welding or other composite laser welding, the post-welding cracks formed by the composite light source combined with swing welding of the present invention only appear at the tail, which greatly improves the welding quality.

[0055] Compared with double beam hybrid welding, the present invention has the following advantages: 1. The present invention takes into account that the absorption rate of aluminum alloy materials for infrared light is only 3%-5%, which can reach 30%-60% after melting. After the pinhole is formed and the Fresnel effect is generated, the absorption rate can reach 90%. Therefore, the surface state of the aluminum alloy is very important for the laser absorption rate, and the absorption rate of aluminum alloy for blue light can reach more than 10%. When blue light is used as a composite light source, the surface of the material can be molten, thereby greatly improving the absorption rate of the aluminum alloy for near-infrared laser. Compared with the composite light beam of semiconductor laser and fiber laser, there is no need for high-power semiconductor laser to preheat (high-power laser preheating will cause the weld width to be too large), and a smaller laser power can be used to meet the welding requirements, reducing energy consumption and improving work efficiency.

[0056] 2. The near-infrared laser beam and the blue light laser beam of the present invention are concentrically arranged and emit light at the same time, and the large diameter spot of the blue light is used for preheating in advance, without the need to reserve additional preheating time. Compared with the existing composite beam welding method of emitting light for preheating first and then emitting light for welding, the welding efficiency is greatly improved.

[0057] 3. The present invention selects the appropriate fiber core diameter, power and wavelength of the near-infrared laser so that the welding laser has high energy density, small heat input and deformation, and is more suitable for aluminum alloy welding. At the same time, by setting the swing amplitude and frequency of the composite welding head and controlling the action time of the near-infrared laser beam and the aluminum alloy, the energy distribution of the weld is more uniform, which is more conducive to the discharge of pores and better pore state after welding.

[0058] 4. The present invention can weld aluminum alloy specimens with relatively large thickness (1-2 mm for the upper layer and 2 mm for the lower layer), which can overcome the problem that the greater the thickness, the greater the energy required and the greater the risk of defects, and achieve high-quality welding with large penetration depth, less spatter and cracks.

[0059] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A 7 series aluminum alloy composite light source laser welding method, characterized in that: A composite beam formed by a near-infrared laser beam and a blue laser beam is used to stack weld a double-layer 7 series aluminum alloy specimen, wherein the thickness of the upper layer of the 7 series aluminum alloy specimen is 1-2 mm, and the thickness of the lower layer of the 7 series aluminum alloy specimen is 2 mm; Before welding, remove the oxide layer on the surface of the aluminum alloy and press it up and down with a jig to set the welding parameters and path; During welding, the spots of the near-infrared laser beam and the blue laser beam are concentric and emitted simultaneously. The two laser beams are coupled and focused on the swing welding head, and the overlap welding is performed according to the set welding parameters and path. The spot diameter of the blue laser beam is larger than the spot diameter of the near-infrared laser beam.

2. According to claim 1, a 7-series aluminum alloy composite light source laser welding method is characterized in that: After welding, metallographic inspection is used to obtain the internal state of the weld, and a digital microscope is used to measure the crack length and pore area to obtain the welding effect.

3. According to claim 2, a 7-series aluminum alloy composite light source laser welding method is characterized in that: The metallographic detection comprises: cutting the welded parts after lap welding along the weld XYZ respectively, grinding and polishing with 80-5000 mesh sandpaper after cutting, mounting the sample with a mounting machine after grinding and polishing, and finally abrading with Keller reagent for a set time.

4. According to claim 1, a 7-series aluminum alloy composite light source laser welding method is characterized in that: Before welding, a nanosecond MOPA laser was used to remove the oxide layer, and a bow-shaped filling was set to scan the laser incident surface and the contact surface of the upper and lower aluminum alloy specimens.

5. According to claim 1, a 7-series aluminum alloy composite light source laser welding method is characterized in that: Among the welding parameters, the adjustable parameters include dual laser power, welding speed, welding head swing amplitude, welding head swing frequency and shielding gas flow rate.

6. A 7-series aluminum alloy composite light source laser welding method according to claim 5, characterized in that: Before welding, set the near-infrared laser power to 500-900W, the blue light laser power to 500W, the welding speed to 50-150mm / s, the welding head swing amplitude to 0.8mm, the welding head swing frequency to 100-300Hz, and the swing pattern to a circle.

7. The composite light source laser welding method for 7 series aluminum alloy according to claim 1, characterized in that: Before welding, plan the processing path and control the moving path through coordinates, setting the moving length to 20 mm.

8. The 7-series aluminum alloy composite light source laser welding method according to claim 1, characterized in that: During welding, turn on the shielding gas and adjust the shielding gas flow rate to 20L / min.

9. The 7-series aluminum alloy composite light source laser welding method according to claim 1, characterized in that: The core diameter of the optical fiber of the near-infrared laser is 14 um.

10. A 7 series aluminum alloy composite light source laser welding system, characterized in that: The invention comprises a near-infrared laser, a blue laser, an oscillating welding head and a jig for pressing a double-layer 7 series aluminum alloy specimen. The near-infrared laser and the blue laser emit laser beams simultaneously, and the two laser beams are coupled and focused to the oscillating welding head, and the double-layer 7 series aluminum alloy specimen is overlap-welded according to the set welding parameters and paths; wherein the thickness of the upper 7 series aluminum alloy specimen is 1-2mm, and the thickness of the lower 7 series aluminum alloy specimen is 2mm; the spots of the near-infrared laser beam and the blue laser beam are concentric, and the spot diameter of the blue laser beam is larger than the spot diameter of the near-infrared laser beam.

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