Short-long wave laser hybrid welding method for aluminum alloy

Abstract

The invention discloses a short-long wave laser hybrid welding method for aluminum alloy, and belongs to the field of laser welding. The method comprises the following steps: firstly, treating the surface of the aluminum alloy by adopting short-wavelength laser as a pretreatment laser source to enable the surface of the aluminum alloy to be in a molten state; according to the method, aluminum is pre-melted, then long-wavelength laser is adopted for welding, due to the fact that the reflectivity of the aluminum to the infrared laser in the liquid state is remarkably reduced, the pre-melting step creates conditions for follow-up long-wavelength infrared laser welding, the absorption rate of the infrared laser is remarkably improved, and loss of laser energy is reduced; according to the process, the utilization rate of welding energy is optimized and the welding quality is improved by utilizing different heating effects of lasers with different wavelengths on the surface of the aluminum alloy.

Description

Technical Field

[0001] The invention belongs to the field of laser welding, and in particular relates to a short-long wave laser composite welding method for aluminum alloy. Background Art

[0002] Aluminum alloys are widely used in aerospace, automobile, shipbuilding and other fields due to their light weight, high strength and good corrosion resistance. Laser welding of aluminum alloys has the advantages of high precision, high speed and low deformation. At present, aluminum alloy laser welding mainly uses infrared wavelength lasers (1030-1070nm), but aluminum alloys have the highest reflectivity to infrared lasers, which can reach more than 90%, reducing energy utilization and welding efficiency. At the same time, high reflectivity may also cause damage to the laser. In contrast, aluminum alloys have a lower reflectivity to short-wavelength lasers. For example, the reflectivity of aluminum alloys to green wavelength lasers (515-532nm) is about 60%, but the low energy density of short-wavelength lasers is only suitable for thin plate welding. Therefore, a new method for short-long wave laser composite welding of aluminum alloys is proposed, that is, a green wavelength laser is set before the infrared wavelength laser, and the surface of the aluminum alloy is first pre-melted using the green laser, and then welded using the red laser. This composite laser welding process can achieve higher welding efficiency and welding quality, and provides a more economical solution for the efficient application of aluminum alloys in the manufacturing field. Summary of the invention

[0003] The present invention provides an aluminum alloy welding process based on a composite of short-wavelength and long-wavelength lasers. The process utilizes the different heating effects of lasers of different wavelengths on the surface of the aluminum alloy to optimize the utilization rate of welding energy and improve the welding quality. Specifically, a short-wavelength green laser (515-532nm) is used as a pretreatment laser source to preheat the surface of the aluminum alloy with its lower reflectivity, so that a thin layer of liquid aluminum is formed on the surface. Since the reflectivity of aluminum to infrared lasers is significantly reduced in liquid state, this pre-melting step creates conditions for subsequent long-wavelength infrared laser (1030-1070nm) welding, significantly improves the absorption rate of infrared lasers, and reduces the loss of laser energy.

[0004] The present invention discloses a short-wave laser composite welding method for aluminum alloy, which specifically comprises the following steps:

[0005] Step 1: Fix the aluminum alloy on the welding platform and pre-treat the surface of the area to be welded;

[0006] Step 2: Fix the position of the dual lasers, with the short-wavelength laser located at the front end of the long-wavelength laser, adjust the angle and focal distance of the dual lasers, and adjust the angle between the wire feeding device and the substrate plane to ensure that the welding wire enters the center of the infrared laser spot; the front end of the dual lasers is provided with a shielding gas, which is turned on during the whole process; the rear end of the dual lasers is provided with a wire feeder and welding wire, and the welding wire is fed into the optical fiber spot of the long-wavelength laser through the wire feeder;

[0007] Step 3: Turn on the protective gas, turn on the short-wavelength laser to preheat the welding surface, and adjust the power parameters so that the short-wavelength laser forms a slight melting layer on the surface of the welding area; the melting layer is the molten state of the aluminum alloy surface.

[0008] Step 4: Turn on the long wavelength laser and the wire feeder to feed the welding wire; use the long wavelength laser to weld the area treated by the short wavelength laser; the optical fiber of the long wavelength laser is perpendicular to the surface of the area to be welded; the long wavelength laser continues to heat the surface of the molten layer to produce a deep molten pool to achieve welding.

[0009] Furthermore, in step 2, the protective gas is argon gas with a flow rate of 15 to 20 L / min.

[0010] Furthermore, in step 3, the wavelength of the short-wavelength laser is 515-532 nm, the power is 800-1000 W, the spot diameter is 0.3-0.5 mm, and the moving speed is 20-30 mm / s.

[0011] Furthermore, in step 4, the wavelength of the long wavelength laser is 1030-1070 nm, the power is 4-5 kW, the spot diameter is 1.0-1.5 mm, and the moving speed is 10-15 mm / s.

[0012] Furthermore, in step 3, the angle between the center line of the optical fiber of the short-wavelength laser and the center line of the optical fiber of the long-wavelength laser is 10 to 15°; in step 4, the angle between the center line of the optical fiber of the long-wavelength laser and the center of the spot where the wire feeder feeds the welding wire is 45 to 60°.

[0013] Furthermore, the short-wavelength laser and the long-wavelength laser are 40 to 50 mm away from the surface of the aluminum alloy.

[0014] The beneficial effects of the present invention are:

[0015] The energy utilization rate of the aluminum alloy welding process method of the present invention is improved. Through green light pre-melting, the high reflection problem of aluminum alloy to infrared laser is reduced, so that the infrared laser can heat the welding area more effectively, thereby improving the overall energy utilization rate.

[0016] The weld quality of the aluminum alloy welding process of the present invention is improved, and the pre-melted liquid aluminum surface is conducive to the stable welding of the subsequent infrared laser, and the depth and uniformity of the weld are improved. The process reduces pores and cracks during the welding process and improves the strength and density of the welded joint.

[0017] In the present invention, the heat input of the infrared laser is concentrated on the surface of the pre-treated liquid aluminum, thereby reducing heat loss, shortening the welding time and improving the welding efficiency.

[0018] The present invention is not only suitable for thin plate welding, but also can realize efficient welding of thick plate aluminum alloy by properly adjusting the power and speed of green light and infrared laser. This short-long wave composite laser process provides a new technical solution for efficient and low-cost welding of aluminum alloy, especially for industrial fields with high requirements on welding quality, such as aerospace, automobile and electronic manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the short-long wave laser composite welding process of aluminum alloy.

[0020] Among them, 1- red light fiber center line, 2- green light fiber center line, 3- red light laser, 4- green light laser, 5- wire feeder, 6- welding wire, 7- shielding gas, 8- distance between red and green light spots on the surface of base material, 9- aluminum alloy base material. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings.

[0022] The present invention discloses a short-wave laser composite welding aluminum alloy process method, comprising the following steps:

[0023] Step 1: Pre-treat the surface of the aluminum alloy to be welded. Fix the workpiece on the welding platform, clean the aluminum alloy surface to remove oxides and impurities, and ensure that the welding area surface is flat and pollution-free to ensure uniform absorption of laser energy.

[0024] Step 2: Fix the position of the dual lasers, with the short-wavelength laser in front and the long-wavelength laser in the back, adjust the angle and focal distance of the dual lasers, and adjust the angle between the wire feeding device and the substrate plane to ensure that the welding wire is fed into the center of the long-wavelength laser spot.

[0025] Step 3: Use short-wavelength laser (green laser, wavelength 515-532nm) to preheat the surface of the welding area. Set the short-wavelength laser in front of the welding path and adjust the power parameters so that the short-wavelength laser forms a slight melting layer on the surface of the welding area. Through the low reflectivity heating of short-wave green light, a thin layer of liquid aluminum is formed on the aluminum surface, reducing its reflectivity and creating good absorption conditions for the subsequent welding process.

[0026] Step 4: Apply long-wavelength laser (infrared laser, wavelength 1030-1070nm) to the pretreated area for welding. The long-wavelength laser follows the short-wavelength laser and continues to heat the low-reflection liquid aluminum layer to produce a deep molten pool, thereby achieving efficient welding. Adjust the long-wavelength infrared laser power and welding speed to ensure appropriate heat input and form a high-quality weld.

[0027] Example

[0028] Combined with Figure 1 The present invention provides a schematic diagram of a short-wave laser composite welding process for aluminum alloy. The following is a specific implementation method based on butt welding of 8 mm thick aluminum alloy:

[0029] Before welding, fix the 8mm thick aluminum alloy base material on the welding platform, clean the surface of the welding area to remove oxides and impurities, and ensure uniform absorption of the laser. In terms of equipment layout, the green laser 4 is placed in the front for pre-melting treatment, and the infrared laser 3 follows closely for deep melting welding. The red light fiber center line 1 generated by the infrared laser 3 and the green light fiber center line 2 generated by the green laser 4 are 1 to 2mm apart on the substrate. The height of the two lasers from the surface of the aluminum alloy base material is 40 to 50mm.

[0030] During the welding process, the fiber laser uses a continuous wave working mode, and the cooling method is water cooling. First, the aluminum alloy surface on the welding path is pre-melted by the short-wave laser (wavelength 515-532nm) of the green laser 4, the power is set at 800-1000W, the spot diameter is 0.3-0.5mm, and the moving speed is 20-30mm / s. The green laser energy partially melts the surface of the aluminum alloy to form a 0.1-0.2mm molten layer, thereby reducing the reflectivity of the aluminum surface. Next, the red laser 3 emits a long-wave laser (wavelength 1030-1070nm), heating the pre-melted aluminum alloy thin layer at a welding speed of 10-15mm / s with a power of 4-5kW, and the spot diameter is 1.0-1.5mm. At the same time, the wire feeder 5 feeds the welding wire 6 into the center of the red light spot at a speed of 1 to 2 m / min, and maintains an angle α of 45 to 60° with the red light fiber centerline 1 to ensure that the welding wire is fully melted. The angle β between the red and green lights is set to 10 to 15° to achieve the best overlap of the light spots. The entire process uses a protective gas 7 (such as argon) with a flow rate set to 15 to 20 L / min to reduce possible oxidation during welding, and ultimately form a weld with high strength and density.

[0031] By using this short-long wave composite welding process, the aluminum alloy surface is pre-melted to significantly reduce the reflectivity and improve the energy utilization of the red laser. The final weld has a uniform and dense microstructure, and the tensile strength and ductility of the weld meet the expected requirements, achieving efficient welding of 8mm aluminum alloy thick plates.

[0032] This set of parameters achieves deep welding of 8mm thick aluminum alloy, while greatly improving the laser energy utilization rate, making it suitable for efficient welding of thick plate aluminum alloy.

[0033] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0034] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A short-long wave laser composite welding method for aluminum alloy, characterized in that: The specific steps include: Step 1: Fix the aluminum alloy on the welding platform and pre-treat the surface of the area to be welded; Step 2: Fix the position of the dual lasers, with the short-wavelength laser located at the front end of the long-wavelength laser, adjust the angle and focal distance of the dual lasers, and adjust the angle between the wire feeding device and the substrate plane to ensure that the welding wire enters the center of the infrared laser spot; the front end of the dual lasers is provided with a shielding gas, which is turned on during the whole process; the rear end of the dual lasers is provided with a wire feeder and welding wire, and the welding wire is fed into the optical fiber spot of the long-wavelength laser through the wire feeder; Step 3: Turn on the protective gas, turn on the short-wavelength laser to preheat the welding surface, and adjust the power parameters so that the short-wavelength laser forms a slight melting layer on the surface of the welding area; Step 4: Turn on the long-wavelength laser, turn on the wire feeder to feed the welding wire; use the long-wavelength laser to weld the area treated by the short-wavelength laser; the optical fiber of the long-wavelength laser is perpendicular to the surface of the area to be welded; The long wavelength laser continues to heat the surface of the molten layer to generate a deep molten pool to achieve welding.

2. The short-wave laser composite welding method for aluminum alloy according to claim 1, characterized in that: In step 2, the protective gas is argon gas with a flow rate of 15 to 20 L / min.

3. The short-wave laser composite welding method for aluminum alloy according to claim 1, characterized in that: In step 3, the wavelength of the short-wavelength laser is 515-532 nm, the power is 800-1000 W, the spot diameter is 0.3-0.5 mm, and the moving speed is 20-30 mm / s.

4. The short-wave laser composite welding method for aluminum alloy according to claim 1, characterized in that: In step 4, the wavelength of the long wavelength laser is 1030-1070 nm, the power is 4-5 kW, the spot diameter is 1.0-1.5 mm, and the moving speed is 10-15 mm / s.

5. The short-wave laser composite welding method for aluminum alloy according to claim 1, characterized in that: In step 3, the angle between the center line of the optical fiber of the short-wavelength laser and the center line of the optical fiber of the long-wavelength laser is 10-15°; in step 4, the angle between the center line of the optical fiber of the long-wavelength laser and the center of the spot where the wire feeder feeds the welding wire is 45-60°.

6. The short-wave laser composite welding method for aluminum alloy according to claim 1, characterized in that: The short-wavelength laser and the long-wavelength laser are 40 to 50 mm away from the surface of the aluminum alloy.

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