Laser wire filling welding method for aluminum alloy corner joints

Abstract

The invention relates to the technical field of welding, and discloses a laser wire filling welding method for an aluminum alloy corner joint, which comprises the following steps: cleaning a to-be-welded part before welding; the panel and the web plate are in gapless angle joint; the panel and the web are positioned and welded through a handheld laser welding gun; formal welding is conducted on the panel and the web through a handheld laser welding gun; wherein the laser power of the handheld laser welding gun ranges from 2400 W to 3000 W; the wire feeding speed of the laser wire feeder in the formal welding process is 100 cm / min to 150 cm / min; in the formal welding process, the laser swing amplitude ranges from 3.8 mm to 5.5 mm; the defocusing amount of the laser in the formal welding is 0 mm to 5 mm; by controlling the laser output power, the laser swing amplitude and the laser defocusing amount, the welding wire is heated more evenly and reasonably, the temperature at the welding seam is prevented from being too high, air holes in the welding seam are fewer, the heat input amount at the welding seam is more stable and reliable, and aluminum alloy is not prone to deformation.

Description

Technical Field

[0001] The invention relates to the technical field of welding, in particular to a laser wire-filling welding method for aluminum alloy fillet joints. Background Art

[0002] Due to its inherent low density, rapid cooling rate, and the influence of welding methods, aluminum alloys are easily oxidized and absorb hydrogen during the welding process. This hydrogen has no time to escape, easily forming pores in the weld area. Aluminum alloys also have high thermal conductivity and a large coefficient of expansion. The temperature of the weld and heat-affected zone rises rapidly during welding, and after cooling, it generates significant shrinkage and internal stress, causing deformation of the aluminum alloy. This is especially true in fillet welds of thinner panel profiles, where excessive heat input can easily cause deformation, leading to precision errors in components and sections.

[0003] Aluminum alloys are typically welded using traditional welding methods such as TIG (metal inert gas arc welding) and MIG (metal inert gas arc welding). However, these methods suffer from slow welding speeds, reliance on operator skill, unstable weld quality, and a large heat-affected zone. Laser welding with filler wire also presents similar challenges, including excessive weld heat input, deformation of the weld angle after welding, difficulty in removing pores in the weld, and low welding efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: how to improve the welding quality of laser welding with filler wire. In order to solve the above technical problem, the present invention provides a laser welding method for aluminum alloy fillet joints with filler wire, which is applied to a laser welding system. The laser welding system includes a handheld laser welding gun, a laser host, a gas cylinder and a laser wire feeder. The laser host is connected to the handheld laser welding gun, the gas cylinder and the laser wire feeder respectively, and the laser wire feeder is also connected to the handheld laser welding gun. The welding method includes:

[0005] S1. Before welding, clean the areas to be welded on the face plate and web;

[0006] S2, make the face plate and the web plate fillet joint without gap;

[0007] S3. Position welding the face plate and the web using a handheld laser welding gun;

[0008] S4. Perform formal welding of the face plate and web using a handheld laser welding gun;

[0009] Among them, the power of the laser output by the handheld laser welding gun is 2400W to 3000W; the wire feeding speed of the laser wire feeder in formal welding is 100cm / min to 150cm / min; the swing amplitude of the laser in the formal welding process is 3.8mm to 5.5mm; the defocus amount of the laser in the formal welding process is 0mm to 5mm.

[0010] Preferably, the light source of the handheld laser welding gun is an annular composite light spot, and the laser power output by the handheld laser welding gun is 2600W to 2900W.

[0011] Preferably, the wire feeding speed of the laser wire feeder is 135 cm / min to 145 cm / min.

[0012] Preferably, the diameter of the welding wire ranges from 1.2 mm to 2.0 mm.

[0013] Preferably, the laser has an oscillation amplitude of 5.0 mm to 5.5 mm during the formal welding process.

[0014] Preferably, the scanning speed of the laser during the formal welding process is 380 mm / s to 500 mm / s.

[0015] Preferably, the defocus amount of the laser during the formal welding process is 1 mm to 3 mm.

[0016] Preferably, the height of the tack weld fillet is half the height of the regular weld fillet.

[0017] Preferably, the angle between the welding wire and the laser is 25° to 35°, the angle between the direction of the laser emitted from the welding gun and the extension direction of the weld is 30° to 40°, and the angle between the direction of the laser emitted from the welding gun and the plate surface of the web and panel is 45°.

[0018] Preferably, step S1 includes the following steps:

[0019] S11, using acetone to remove oil stains;

[0020] S12. Use a stainless steel wire brush with a diameter of less than 0.5 mm to polish the face plate and web to remove the surface oxide film in the area to be welded on the face plate and web;

[0021] The scope of removing the surface oxide film includes the seams to be welded on the face plate and web, and the area of 0mm to 20mm on both sides of the seams to be welded.

[0022] Compared with the prior art, the laser wire-filling welding method for aluminum alloy fillet joints provided in the embodiment of the present invention has the following advantages:

[0023] In the present invention, a laser wire filling method is used to weld aluminum alloy materials. By controlling the output power of the laser, the swing amplitude of the laser during the welding process, and the defocus amount of the laser, the heating of the welding wire is made more uniform and reasonable, avoiding excessive temperature at the weld, making the weld quality better after welding, with fewer pores in the weld, the heat input at the weld more stable and reliable, and the aluminum alloy is less likely to deform. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view of the mechanical welding system of the present invention;

[0025] Figure 2 It is a schematic flow diagram of the present invention.

[0026] In the picture: 1. Handheld welding gun; 2. Laser host; 3. Gas cylinder; 4. Laser wire feeder. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0028] like Figure 1 and Figure 2 As shown, a preferred embodiment of the present invention provides a laser wire-filling welding method for aluminum alloy fillet joints, which is applied to a laser welding system. The laser welding system includes a handheld laser welding gun, a laser host, a gas cylinder, and a laser wire feeder. The laser host is connected to the handheld laser welding gun, the gas cylinder, and the laser wire feeder respectively, and the laser wire feeder is also connected to the handheld laser welding gun. The welding method includes:

[0029] S1. Before welding, clean the areas to be welded on the face plate and web;

[0030] S2, make the face plate and the web plate fillet joint without gap;

[0031] S3. Position welding the face plate and the web using a handheld laser welding gun;

[0032] S4. Perform formal welding of the face plate and web using a handheld laser welding gun;

[0033] Among them, the power of the laser output by the handheld laser welding gun is 2400W to 3000W; the wire feeding speed of the laser wire feeder in formal welding is 100cm / min to 150cm / min; the swing amplitude of the laser in the formal welding process is 3.8mm to 5.5mm; the defocus amount of the laser in the formal welding process is 0mm to 5mm.

[0034] Specifically, in the actual operation process, the handheld laser welding gun is connected to the laser host and the laser wire feeder at the same time, and the gas cylinder is connected to the handheld laser welding gun through the laser host. Both the laser host and the laser wire feeder can be moved to ensure the portability of the equipment and meet the needs of use in a variety of different scenarios. In addition, the handheld laser welding gun is a dual-laser optical path system, and its emitting light source is an annular composite spot. The outer ring laser spot is used to preheat the weldment, stabilize the molten pool, and expand the keyhole, thereby reducing the pores in the weld and reducing the spatter of the solder, thereby improving the laser absorption rate of the welded part. The central laser spot located in the center is used to increase the penetration depth, thereby improving the welding quality. Of course, the handheld laser welding gun can adjust the parameters and specifications of the optical path system and the wire feeding device to adapt to aluminum alloy workpieces of different thicknesses and shapes.

[0035] Secondly, the laser host uses a 3000W high-power dual-laser light source to ensure sufficient laser power density during the welding process, preventing the weld from solidifying too quickly and preventing gas from escaping quickly, thus forming porosity defects. The laser host can control the coordinated operation of the laser light source, gas supply system, welding gun, and wire feeder, stabilizing the gas supply, wire feeding, and laser emission states, ensuring that the shielding gas protects the weld throughout the welding process. The welding wire is melted by the laser during the welding process and evenly fills the weld, ensuring the stability of the welding process and the quality of the weld.

[0036] Finally, the faceplate and web are preferably 3mm to 5mm thick and made of aluminum alloy. Too thin a thickness can lead to low weld penetration, poor weld quality, and unstable welding. Too thick a thickness can result in incomplete weld penetration, impacting weld quality. During welding, the assembly gap between the control panel and web must be less than 0.5mm. The faceplate and web must abut vertically.

[0037] In some embodiments, the light source of the handheld laser welding gun is an annular composite light spot, and the laser power output by the handheld laser welding gun is 2600W to 2900W.

[0038] Furthermore, the wire feeding speed of the laser wire feeder is 135 cm / min to 145 cm / min.

[0039] Depending on the actual welding process, the specific settings of welding parameters will also be different:

[0040]

[0041] When the weld angle is larger than 4mm, the sufficient thickness of the faceplate and web allows for a maximum power of 2900W and a higher wire feed speed. However, for welds with smaller angles, the laser power should be appropriately reduced and the wire feed speed should be slowed to allow for sufficient melting of the wire. Insufficient welding power results in excessively rapid weld solidification, preventing gases from escaping and forming porosity. Excessive welding power leads to excessively high weld temperatures and coarse grains, which affect material properties and, in turn, weld quality. The wire feed speed must be matched to the laser power. Increasing the wire feed speed increases the welding speed, preventing the laser from effectively melting the base material and wire, resulting in incomplete fusion and discontinuous welds. Slowing the wire feed speed also slows the welding speed, slowing the fill rate of the weld pool and increasing the heat input, which can lead to weld metal oxidation, increased weld penetration, and ultimately, increased weld distortion.

[0042] In a specific control test, aluminum alloy grade 1561 was selected, the thickness of the face plate and web were both 4 mm, the welding wire diameter was 2 mm, and the weld type was fillet welding. The specific test results are as follows:

[0043]

[0044] Therefore, when performing fillet welding on two 4mm thick 1561 aluminum alloy plates, the optimal welding laser power is 2800W and the wire feed speed is 1.45m / min. It should be noted that according to welding specifications, when the weldment thickness is less than 6mm, the weld fillet size is equal to the plate thickness of the weldment.

[0045] In some embodiments, the diameter of the welding wire ranges from 1.2 mm to 2.0 mm.

[0046] Small fillet sizes can result in weld strength failing to meet design requirements, and different wire diameters can affect fillet sizes. Therefore, it's necessary to select different wire diameters for different welding scenarios. In a specific example, 1561 aluminum alloy was selected, with both the face plate and web thicknesses of 4 mm, a double-wire filler wire used, and a fillet weld as the welding location. The experimental results for different wire diameters are as follows:

[0047] Wire diameter (mm) Welding angle size (mm) 1.2 1.0-1.5 1.6 2.0-2.5 2.0 2.7-3.3

[0048] Therefore, in this embodiment, the diameter of the welding wire is preferably 2 mm, so that the size of the weld angle after welding meets the strength requirements in the design. Of course, in other embodiments, the diameter of the welding wire can also be selected to be larger to meet other welding requirements.

[0049] In some embodiments, the laser oscillation amplitude during the actual welding process is 5.0 mm to 5.5 mm.

[0050] Furthermore, the scanning speed of the laser during the formal welding process is 380 mm / s to 500 mm / s.

[0051] Specifically, during the actual welding process, the laser's swing amplitude has a direct impact on weld fusion. When the laser swing amplitude is too small, the spot cannot effectively cover the welding wire and the joint surface, resulting in poor fusion. When the laser swing amplitude is too large, the filler metal cannot effectively cover the laser-bombarded area, resulting in weld undercut defects. If the scanning speed is too slow, the weld will be unevenly fused, while if the scanning speed is too high, the welding wire will not be fully melted, which will seriously affect the welding quality.

[0052] In the actual welding process, the laser swing amplitude and scanning speed will vary according to the size of the weld angle, as follows:

[0053] Welding angle size (mm) Laser swing amplitude (mm) Scanning speed (mm / s) 2 3.8-4.0 500 3 4.0-5.0 500 4 5.0-5.2 500

[0054] In a specific embodiment, when the diameter of the welding wire is 2.0 mm, the thickness of the face plate and the web is 4 mm, the spacing between the two welding wires is about 4.5 mm, and the preferred laser oscillation amplitude is 5.2 mm.

[0055] In some embodiments, the defocus amount of the laser during the formal welding process is 1 mm to 3 mm.

[0056] Specifically, in the actual laser welding process, due to the excessive power density at the center of the laser spot at the laser focus, it is easy to evaporate and form holes. The power density distribution is relatively uniform in all planes away from the laser focus. At the same time, the high reflectivity of aluminum alloy materials leads to low laser absorption rate. Excessive defocusing will also cause the distance between the laser focus and the base material to be too large. The energy absorbed by the face plate and web at the weld is too low, resulting in incomplete melting of the weld base material, which in turn affects the welding quality. In actual operation, different defocusing amounts were tested on aluminum alloy with the grade of 1561. The specific test results are as follows:

[0057]

[0058] Therefore, during the actual welding process, the laser defocus must be limited to a range of 1 mm to 3 mm.

[0059] In some embodiments, the height of the tack weld fillet is half the height of the main weld fillet. Tack welds ensure accurate positioning of the faceplate and web, preventing misalignment between the faceplate and web during the main welding process. Limiting the tack weld fillet height avoids the need for polishing the tack weld prior to the main welding process, improving welding efficiency and ensuring overall structural strength after welding.

[0060] In some embodiments, the angle between the welding wire and the laser is 25° to 35°, the angle between the direction of the laser emitted from the welding gun and the extension direction of the weld is 30° to 40°, and the angle between the direction of the laser emitted from the welding gun and the plate surface of the web and face plate is 45°. Specifically, the above parameters are set to ensure that the base material and the welding wire are fully melted by the laser at the same time, control the penetration depth of the weld, prevent the laser from burning through the base material, and prevent the weld from being offset and resulting in incomplete weld fusion.

[0061] In some embodiments, step S1 includes the following steps:

[0062] S11, using acetone to remove oil stains;

[0063] S12. Use a stainless steel wire brush with a diameter of less than 0.5 mm to polish the face plate and web to remove the surface oxide film in the area to be welded on the face plate and web;

[0064] The scope of removing the surface oxide film includes the seams to be welded on the face plate and web, and the area of 0mm to 20mm on both sides of the seams to be welded.

[0065] In addition, after the formal welding, it is also necessary to use a 0.5mm stainless steel wire brush to remove the oxide film on the weld surface and correct the surface unevenness and defects;

[0066] During the formal welding process, it is necessary to ensure that the weld is completed in one go; in addition, when the weld is more than 1 meter long, the segmented return welding method is required for formal welding;

[0067] Before positioning welding, exhaust operation is required to remove residual air and moisture in the gas cylinder gas pipeline to ensure the purity of the shielding gas. After the exhaust operation is completed, the argon shielding medium needs to be tested for ≥99.995% requirement.

[0068] In summary, the embodiment of the present invention provides a laser wire-filling welding method for aluminum alloy corner joints. When facing the corner welding of aluminum alloy plates with a thickness of 3mm to 5mm, the method reduces the number of pores in the weld after welding by limiting the laser output power, laser defocus, laser swing amplitude and wire feeding speed during the laser welding process, so that the welding wire can be fully melted, and at the same time improves the welding speed, reduces the accumulation and diffusion transmission of heat at the weld, and makes the welding high-temperature gradient narrow. After the welding is completed, the stress concentration of the product structure is smaller and the deformation is smaller.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A laser wire-filling welding method for aluminum alloy fillet joints, applied to a laser welding system, the laser welding system comprising a handheld laser welding gun, a laser host, a gas cylinder, and a laser wire feeder, the laser host being connected to the handheld laser welding gun, the gas cylinder, and the laser wire feeder, respectively, and the laser wire feeder being further connected to the handheld laser welding gun; characterized in that: The welding method comprises: S1. Before welding, clean the areas to be welded on the face plate and web; S2, make the face plate and the web plate fillet joint without gap; S3. Position welding the face plate and the web using a handheld laser welding gun; S4. Perform formal welding of the face plate and web using a handheld laser welding gun; Among them, the power of the laser output by the handheld laser welding gun is 2400W to 3000W; the wire feeding speed of the laser wire feeder during formal welding is 100cm / min to 150cm / min; the swing amplitude of the laser during the formal welding process is 3.8mm to 5.5mm; the defocus amount of the laser during the formal welding process is 0mm to 5mm.

2. The laser wire welding method for aluminum alloy fillet joints according to claim 1, characterized in that: The light source of the handheld laser welding gun is an annular composite light spot, and the laser power output by the handheld laser welding gun is 2600W to 2900W.

3. The laser wire welding method for aluminum alloy fillet joints according to claim 2, characterized in that: The wire feeding speed of the laser wire feeder is 135 cm / min to 145 cm / min.

4. The laser wire welding method for aluminum alloy fillet joints according to claim 1, characterized in that: The diameter of the welding wire ranges from 1.2 mm to 2.0 mm.

5. The laser wire-filling welding method for aluminum alloy fillet joints according to claim 4, characterized in that: The laser's swing amplitude during the actual welding process is 5.0 mm to 5.5 mm.

6. The laser wire-filling welding method for aluminum alloy fillet joints according to claim 5, characterized in that: The scanning speed of the laser during the formal welding process is 380 mm / s to 500 mm / s.

7. The laser wire welding method for aluminum alloy fillet joints according to claim 1, characterized in that: During the formal welding process, the defocus amount of the laser is 1 mm to 3 mm.

8. The laser wire welding method for aluminum alloy fillet joints according to claim 1, characterized in that: The height of the tack weld fillet is half the height of the regular weld fillet.

9. The laser wire-filling welding method for aluminum alloy fillet joints according to claim 1, characterized in that: The angle between the welding wire and the laser is 25° to 35°, the angle between the direction of the laser emitted from the welding gun and the extension direction of the weld is 30° to 40°, and the angle between the direction of the laser emitted from the welding gun and the plate surface of the web and panel is 45°.

10. The laser wire welding method for aluminum alloy fillet joints according to claim 1, characterized in that: Step S1 includes the following steps: S11. Use acetone to remove oil stains on the face plate, web and welding wire; S12. Use a stainless steel wire brush with a diameter of less than 0.5 mm to polish the face plate and web to remove the surface oxide film in the area to be welded on the face plate and web; The scope of removing the surface oxide film includes the seams to be welded on the face plate and web, and the area of 0mm to 20mm on both sides of the seams to be welded.

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