A method of oscillating spot ring laser-arc hybrid welding

Abstract

The application discloses a swing point ring laser-arc hybrid welding method, and relates to the field of laser processing.The application solves the problems that the existing point ring laser-arc hybrid welding is not applicable to medium-thick wall metal materials and / or materials with high laser reflectivity, and the suppression effect on process pores has limitations.The application cleans the surface of the base material to be welded, and removes oil stains, oxide films and moisture on the surface of the base material;the base material is fixed on a welding experiment platform by using a clamp;the water cooling machine, the laser, the welding robot, the arc welding power supply and the swing laser control cabinet are started to preheat, and the characteristic points in the teaching welding path are demonstrated;the welding process parameters are set, the protection gas is connected, the welding robot moves according to the teaching route, and the swing point ring laser-arc hybrid welding is carried out.The swing point ring laser is obtained by adopting the point ring laser and the swing laser head, the swing point ring laser-arc hybrid welding is realized, and the medium-thick wall metal material welding joint with good forming is obtained.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and specifically to a laser-arc hybrid welding method for oscillating point rings. Background Technology

[0002] Medium-thick-walled metal structures have numerous applications in aerospace, shipbuilding, rail transportation, and the automotive industry. As a highly efficient welding method, laser-arc hybrid welding is widely used in welding medium-thick-walled components. Lasers offer high energy density and a small heating range, resulting in greater penetration depth and a smaller heat-affected zone. The electric arc enhances the gap bridging capability of laser welding and promotes laser absorption by the base material. Simultaneously, the intense outward ejection of photo-induced plasma from the keyhole increases the charged particle density within the arc, enhancing its conductivity and compressing it around the keyhole, thus improving arc stability during welding and leading to high-quality laser-arc hybrid weld joints. However, conventional laser-arc hybrid welding uses the laser as the primary heat source and the arc as an auxiliary heat source. High-power lasers achieve deep penetration in the thickness direction of the base material using a deep-penetration welding mode, while the arc only melts the upper and middle parts of the weld joint, forming a T-shaped weld. In laser deep-penetration welding mode, the keyhole stability is relatively poor. Unstable keyhole closure can easily lead to the formation of numerous large-sized process pores inside the weld, severely reducing the mechanical properties of the welded joint. For materials with high laser reflectivity, such as aluminum alloys and magnesium alloys, the stability of their laser energy absorption is poor, and the tendency for process pores inside the welded joint is even stronger when using high-power lasers for welding.

[0003] The keyhole formed by oscillating laser welding changes position with the oscillation of the laser beam, thus capturing air bubbles inside the molten pool and carrying them out through plasma ejection. Compared to conventional single lasers, oscillating lasers have a larger heating area, a wider keyhole, and enhanced keyhole stability, making them less prone to closure. Therefore, oscillating laser-arc hybrid welding can reduce the porosity inside the weld. However, with increasing laser power, process porosity and spatter still form in the laser action zone of oscillating laser-arc hybrid welding. Point-ring lasers have attracted attention from researchers in recent years. Patent CN 114043092 A, published on February 15, 2022, discloses a point-ring laser-arc hybrid welding method. The point-ring laser consists of an internal point light source and an external ring light source, which can be adjusted separately. The ring light widens the upper surface of the keyhole, enhancing its stability. Using point-ring lasers for laser-arc hybrid welding can suppress process porosity and welding spatter. However, this effect is only achieved in laser-arc hybrid welding of materials with low laser reflectivity, such as steel, and is mostly used for thin-plate welding. For medium-thick-walled materials with a thickness of 4 mm or more, especially materials with high laser reflectivity such as aluminum alloys, millimeter-scale process porosity is caused by keyhole collapse in the laser-affected zone at the bottom of the weld in spot-ring laser-arc hybrid welding, while a large number of metallurgical pores exist in the upper part of the weld. This is because the solubility of gases such as hydrogen in the liquid and solid phases of aluminum alloys is significantly different. During solidification, a large amount of gas is released from the liquid phase and does not escape from the molten pool in time, thus forming pores in the weld. Therefore, the effect of spot-ring laser-arc hybrid welding in suppressing process porosity still has limitations.

[0004] In summary, existing spot-ring laser-arc hybrid welding methods have limitations in their applicability to medium-thick-walled metal materials and / or materials with high laser reflectivity, and also have limitations in their ability to suppress process porosity. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing spot ring laser-arc hybrid welding, which is not suitable for medium-thick-walled metal materials and / or materials with high laser reflectivity, and has limited effect on suppressing process porosity. Therefore, this invention provides an oscillating spot ring laser-arc hybrid welding method.

[0006] The technical solution of this invention is:

[0007] A laser-arc hybrid welding method for oscillating point rings, wherein the hybrid welding method is achieved through the following steps:

[0008] Step 1: Cleaning the base material:

[0009] First, clean the surface of the base material to be welded, and then remove oil, oxide film and moisture from the surface of the base material;

[0010] Step 2: Fixing the base material:

[0011] The base material is then fixed onto the welding test platform 6 using clamps.

[0012] Step 3: Preheat the equipment and demonstrate the route:

[0013] Turn on the water chiller, laser, welding robot 5, arc welding power supply and oscillating laser control cabinet for preheating, and teach the feature points in the welding path;

[0014] Step 4: Oscillating Point Ring Laser-Arc Hybrid Welding

[0015] The welding process parameters are set, the shielding gas is turned on, and the welding robot 5 moves according to the taught route to perform oscillating point ring laser-arc hybrid welding.

[0016] Furthermore, the thickness of the base material in step one is 4–10 mm.

[0017] Furthermore, the base material in step one is an aluminum alloy.

[0018] Furthermore, in step one, an I-shaped, V-shaped, or Y-shaped bevel is processed at the weldable area of ​​the base material.

[0019] Furthermore, in step one, the surface of the base material to be welded is mechanically ground, and then acetone is used to further clean the surface to be welded.

[0020] Furthermore, in step two, a copper U-shaped forced forming groove is fixed directly below the weld.

[0021] Furthermore, in step four, the dot-ring laser consists of an inner dot light and an outer ring light. The dot-ring laser is obtained by connecting a two-in-one fiber to the laser. The two-in-one fiber includes an inner fiber core 21 and an outer ring core 22. The inner fiber core 21 generates dot light, and the outer ring core 22 generates ring light, forming a composite dot-ring laser.

[0022] Furthermore, in step four, the oscillating dot ring laser is obtained by connecting a two-in-one optical fiber to the oscillating laser head 1, which can realize the linear, circular, octagonal and ∞-shaped oscillation of the dot ring laser.

[0023] Furthermore, the welding process parameters in step four are as follows: laser power of 2000-6000W, welding current of 100-320A, welding speed of 0.5-2.5m / min, oscillation frequency of 50-350Hz, oscillation amplitude of 0.5-3mm, defocusing amount of -6-+6mm, wire spacing of 1-3mm, wire extension of 12-15mm, shielding gas flow rate of 15-25L / min, the angle between the laser head and the workpiece surface of 90°, and the angle between the welding torch and the workpiece surface of 55°-75°.

[0024] Furthermore, the wire distance in step four refers to the distance between the point light spot and the intersection of the extension line of the welding wire and the workpiece surface.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] This invention employs a spot-ring laser and a oscillating laser head to generate an oscillating spot-ring laser, achieving oscillating spot-ring laser-arc hybrid welding to obtain well-formed welded joints in medium-thick-walled metal materials. The oscillating spot-ring laser of this invention agitates the molten pool, improving the fluidity of the molten metal and promoting gas escape. Simultaneously, the keyhole generated by the oscillating spot-ring laser oscillates with the laser's movement, capturing gas inside the molten pool and carrying it out with the plasma plume. Therefore, the weld seam produced by oscillating spot-ring laser-arc hybrid welding has no obvious porosity. Attached Figure Description

[0027] Figure 1 This is an isometric drawing of a swing-ring laser-arc composite welding fixture according to the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of a two-in-one optical fiber in a swinging point ring laser-arc composite welding fixture of the present invention;

[0029] Figure 3 This is a schematic diagram of the dot ring laser of a wobbling dot ring laser-arc hybrid welding fixture of the present invention;

[0030] Figure 4 This is a photograph of the cross-sectional morphology of the weld after composite welding in Example 1;

[0031] Figure 5 This is a photograph of the cross-sectional morphology of the weld after composite welding in Comparative Experiment 1.

[0032] In the diagram: 1-Oscillating laser head; 2-Dot ring laser; 21-Inner fiber core; 22-Outer ring core; 3-Welding torch; 4-Adapter; 5-Welding robot; 6-Welding test platform; 7-Welding torch fixture. Detailed Implementation

[0033] Specific implementation method one: Combining Figures 1 to 5 This embodiment describes a laser-arc hybrid welding method for a wobbling spot ring. The hybrid welding method is implemented through the following steps:

[0034] Step 1: Cleaning the base material:

[0035] First, clean the surface of the base material to be welded, and then remove impurities such as oil, oxide film and moisture from the surface of the base material.

[0036] Step 2: Fixing the base material:

[0037] Then, the base material is fixed on the welding test platform 6 using clamps to prevent the welded joint from undergoing large deformation during and after welding.

[0038] Step 3: Preheat the equipment and demonstrate the route:

[0039] Turn on the water chiller, laser, welding robot 5, arc welding power supply and oscillating laser control cabinet and other equipment for preheating, and teach the characteristic points in the welding path;

[0040] Step 4: Oscillating Point Ring Laser-Arc Hybrid Welding

[0041] The welding process parameters are set, the shielding gas is turned on, and the welding robot 5 moves according to the taught route to perform oscillating point ring laser-arc hybrid welding.

[0042] In this embodiment, a oscillating spot-ring laser-arc hybrid welding method is implemented based on an oscillating spot-ring laser-arc hybrid welding fixture. The hybrid welding fixture includes an oscillating laser head 1, a laser, a two-in-one optical fiber, a welding torch 3, an adapter 4, a welding robot 5, a welding test platform 6, and a welding torch clamp 7. The adapter 4 is installed at the end effector of the welding robot 5. The oscillating laser head 1 and the welding torch clamp 7 are mounted on the adapter 4, and the welding torch 3 is mounted on the welding torch clamp 7. One end of the two-in-one optical fiber is inserted into the fiber optic interface of the laser, and the other end of the two-in-one optical fiber is connected to the oscillating laser head 1. Along the welding direction, the oscillating laser head 1 is located in front of the welding torch 3, and the relative positions of the oscillating laser head 1 and the welding torch 3 remain unchanged. The two-in-one optical fiber is connected to the laser and is connected to the oscillating laser head 1. The two-in-one optical fiber includes an inner core 21 and an outer ring core 22. The inner core 21 has a diameter of 100 μm, and the outer ring core 22 has a diameter of 400 μm.

[0043] In this embodiment, the oscillating laser head 1 is an IPG-manufactured D50 Wobble.

[0044] Specific Implementation Method Two: Combining Figures 1 to 3 This embodiment describes a method where the base material thickness in step one is 4–10 mm. Other components and connections are the same as in specific embodiment one.

[0045] Specific implementation method three: Combining Figures 1 to 3 This embodiment describes a method where the base material in step one is aluminum alloy. Other components and connections are the same as in specific embodiments one or two.

[0046] Specific implementation method four: Combination Figures 1 to 3 This embodiment describes a step where an I-shaped, V-shaped, or Y-shaped bevel is machined at the weldable area of ​​the base material. Other components and connections are the same as in specific embodiments one, two, or three.

[0047] Specific Implementation Method Five: Combining Figures 1 to 3 This embodiment describes a method where, in step one, the surface of the base material to be welded is mechanically ground, followed by further cleaning with acetone. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0048] Specific Implementation Method Six: Combination Figures 1 to 3 This embodiment describes a copper U-shaped forced forming groove fixed directly below the weld in step two. This arrangement ensures good forming on the back side of the weld. Other components and connections are the same as in specific embodiments one, two, three, four, or five.

[0049] Specific implementation method seven: Combination Figure 1 and Figure 3 This embodiment describes a point-ring laser in step four, which consists of an internal point beam and an external ring beam. The point-ring laser is obtained by connecting a two-in-one fiber to the laser. The two-in-one fiber includes an inner core 21 and an outer ring core 22. The inner core 21 generates point beams, and the outer ring core 22 generates ring beams, forming a composite point-ring laser. Other components and connections are the same as in specific embodiments one, two, three, four, five, or six.

[0050] In this embodiment, the laser power of the point light and the ring light can be adjusted independently to achieve different power ratios.

[0051] Specific implementation method eight: Combination Figures 1 to 3 This embodiment describes a method where, in step four, the oscillating dot-ring laser is obtained by connecting a two-in-one optical fiber to the oscillating laser head 1. This allows for linear, circular, octagonal, and infinity-shaped oscillations of the dot-ring laser, with the oscillation frequency and amplitude freely adjustable. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, or seven.

[0052] Specific Implementation Method Nine: Combining Figures 1 to 3This embodiment describes the welding process parameters in step four as follows: laser power of 2000–6000 W, welding current of 100–320 A, welding speed of 0.5–2.5 m / min, oscillation frequency of 50–350 Hz, oscillation amplitude of 0.5–3 mm, defocusing amount of -6–+6 mm, wire spacing of 1–3 mm, wire extension of 12–15 mm, shielding gas flow rate of 15–25 L / min, the angle between the laser head and the workpiece surface of 90°, the angle between the welding torch and the workpiece surface of 55°–75°, and the laser head being in front of the welding torch 3 along the welding direction, with the relative positions of the laser head and the welding torch 3 remaining unchanged. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, seven, or eight.

[0053] Specific Implementation Method Ten: Combining Figures 1 to 3 In this embodiment, the wire spacing in step four refers to the distance between the point spot of the welding wire and the intersection of the extension line of the welding wire and the workpiece surface. Other components and connections are the same as in embodiments one, two, three, four, five, six, seven, eight, or nine.

[0054] The beneficial effects of the present invention are verified using the following embodiments:

[0055] Example 1, combined with Figures 1 to 5 Detailed explanation:

[0056] A laser-arc hybrid welding method for oscillating point rings, wherein the hybrid welding method is achieved through the following steps:

[0057] Step 1: Cleaning the base material:

[0058] First, clean the surface of the base material to be welded, and then remove impurities such as oil, oxide film and moisture from the surface of the base material.

[0059] Step 2: Fixing the base material:

[0060] Then, the base material is fixed on the welding test platform 6 using clamps to prevent the welded joint from undergoing large deformation during and after welding.

[0061] Step 3: Preheat the equipment and demonstrate the route:

[0062] Turn on the water chiller, laser, welding robot 5, arc welding power supply and oscillating laser control cabinet and other equipment for preheating, and teach the characteristic points in the welding path;

[0063] Step 4: Oscillating Point Ring Laser-Arc Hybrid Welding

[0064] The welding process parameters are set, the shielding gas is turned on, and the welding robot 5 moves according to the taught route to perform oscillating point ring laser-arc hybrid welding.

[0065] In step one, the base material is 5083 aluminum alloy with a thickness of 5mm. An I-shaped bevel is machined at the welding point on the base material, with a bevel gap of 0.5mm. Aluminum alloy has high laser reflectivity and unstable absorption of laser energy, making the keyhole prone to collapse and forming process porosity. Simultaneously, metallurgical pores easily form inside the weld joint of aluminum alloy. Choosing an aluminum alloy with high porosity sensitivity as the base material further highlights the advantages of this invention in suppressing weld porosity.

[0066] In step one, the surface of the base material to be welded is mechanically ground, and then acetone is used to further clean the surface to be welded.

[0067] In step two, a copper U-shaped forced forming groove is fixed directly below the weld to ensure good forming on the back of the weld.

[0068] In step four, the point-ring laser consists of an inner point beam and an outer ring beam. A point-ring laser is obtained by connecting a two-in-one fiber to the laser. The two-in-one fiber includes an inner core and an outer ring core. The inner core generates the point beam, and the outer ring core generates the ring beam, forming a composite point-ring laser. The laser power of the point beam accounts for 80% of the total laser power, and the laser power of the ring beam accounts for 20% of the total laser power.

[0069] In step four, the oscillating dot ring laser is obtained by connecting a two-in-one optical fiber to the oscillating laser head, which can realize the linear, circular, octagonal and ∞-shaped oscillation of the dot ring laser, and the oscillation frequency and oscillation amplitude can be freely adjusted.

[0070] The welding process parameters in step four are as follows: laser power is 3500W, welding current is 150A, oscillation mode is circular oscillation, welding speed is 0.8m / min, oscillation frequency is 100Hz, oscillation amplitude is 1mm, defocusing amount is -2mm, the distance between the spot laser beam and the intersection of the welding wire extension line and the workpiece surface (fiber distance) is 2mm, the welding wire extension is 15mm, the shielding gas is argon with a flow rate of 15L / min, the angle between the laser head and the workpiece surface is 90°, the angle between the welding torch and the workpiece surface is 65°, and the laser head is in front of the welding torch along the welding direction, with their relative positions remaining unchanged.

[0071] Figure 4 This is a photograph of the cross-sectional morphology of the weld after composite welding in Example 1; Figure 4 It can be seen that by using oscillating spot ring laser-arc hybrid welding, there is no obvious porosity in the weld and the weld joint has a good morphology.

[0072] Comparative Experiment 1

[0073] The difference between Comparative Experiment 1 and Example 1 is that Comparative Experiment 1 used a non-oscillating spot-ring laser-arc composite welding method for welding, while other conditions were the same as in Example 1.

[0074] Figure 5 This is a photograph of the cross-sectional morphology of the weld after composite welding in Comparative Experiment 1. Millimeter-scale process pores due to keyhole collapse exist in the laser-affected zone at the bottom of the weld. Numerous metallurgical pores are present in the upper part of the weld. This is due to the significant difference in solubility of gases such as hydrogen in the liquid and solid phases of the aluminum alloy. During solidification, a large amount of gas is released from the liquid phase and fails to escape from the molten pool in time, thus forming pores in the weld. Keyholes form during welding once the laser power reaches the threshold for keyhole formation. To ensure keyhole stability, the laser power needs to be slightly higher than the threshold. The formation of welding process pores is closely related to the molten pool flow. Welding process parameters such as laser power, welding current, welding speed, oscillation mode, oscillation frequency, and oscillation amplitude collectively determine the molten pool flow state. Therefore, welding with parameters within a reasonable range obtained after process optimization experiments can achieve the effect of oscillating point ring laser agitation of the molten pool, improving the fluidity of the molten pool metal, and promoting gas escape. Simultaneously, the keyhole generated by the oscillating ring laser also oscillates with the laser's movement. This keyhole captures gas within the molten pool and carries it out with the plasma plume. Therefore, welds produced using oscillating ring laser-arc hybrid welding exhibit no significant porosity. However, welding with parameters outside the range of those described in this invention can lead to problems such as insufficient heat input, excessive heat input, and unreasonable oscillation parameters, resulting in poor suppression of process porosity.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for laser-arc hybrid welding of oscillating point rings, characterized in that: The welding is achieved based on a swinging point ring laser-arc composite welding fixture. The composite welding fixture includes a swinging laser head (1), a laser, a two-in-one optical fiber, a welding torch (3), an adapter (4), a welding robot (5), a welding experimental platform (6), and a welding torch fixture (7). The welding robot (5) has an adapter (4) installed at its execution end. The swinging laser head (1) and the welding torch fixture (7) are installed on the adapter (4). The welding torch (3) is installed on the welding torch fixture (7). One end of the two-in-one optical fiber is inserted into the optical fiber interface of the laser. The other end of the two-in-one optical fiber is connected to the swinging laser head (1). The swinging laser head (1) is located in front of the welding torch (3) along the welding direction. The relative positions of the swinging laser head (1) and the welding torch (3) remain unchanged. The composite welding method is achieved through the following steps: Step 1: Cleaning the base material: First, select an aluminum alloy with a thickness of 4~10mm as the base material, clean the surface of the base material to be welded, and then remove oil, oxide film and moisture from the surface of the base material. Step 2: Fixing the base material: Then, the base material is fixed on the welding test platform (6) using a clamp, and a copper U-shaped forced forming groove is fixed directly below the weld. Step 3: Preheat the equipment and demonstrate the route: Turn on the water chiller, laser, welding robot (5), arc welding power supply and oscillating laser control cabinet for preheating, and teach the feature points in the welding path; Step 4: Oscillating Point Ring Laser-Arc Hybrid Welding A point-ring laser is obtained by connecting the two-in-one fiber to a laser and a oscillating laser head (1). The two-in-one fiber includes an inner core (21) and an outer ring core (22). The inner core (21) generates point light, and the outer ring core (22) generates ring light, forming a composite point-ring laser composed of the inner point light and the outer ring light. The oscillating laser head (1) is used to oscillate the point-ring laser to obtain an oscillating point-ring laser. The welding process parameters are set as follows: laser power is 2000~6000W, welding current is 100~320A, and welding speed is 0.5~2.

5. m / min, oscillation frequency of 50~350Hz, oscillation amplitude of 0.5~3mm, defocusing amount of -6~+6mm, filament distance of 1~3mm, filament distance refers to the distance between the spot of the laser beam and the intersection of the extension line of the welding wire and the surface of the workpiece, the dry extension of the welding wire is 12~15mm, the shielding gas flow rate is 15~25L / min, the angle between the laser head and the surface of the workpiece is 90°, and the angle between the welding gun and the surface of the workpiece is 55°~75°; when the shielding gas is turned on, the welding robot (5) moves according to the taught route to perform oscillating spot ring laser-arc composite welding.

2. The method for laser-arc hybrid welding of oscillating point rings according to claim 1, characterized in that: In step one, an I-shaped, V-shaped, or Y-shaped bevel is processed at the weldable part of the base material.

3. The method for laser-arc hybrid welding of oscillating point rings according to claim 2, characterized in that: In step one, the surface of the base material to be welded is mechanically ground, and then acetone is used to further clean the surface to be welded.

4. The method for laser-arc hybrid welding of oscillating point rings according to claim 3, characterized in that: In step four, the oscillating point ring laser is obtained by connecting a two-in-one optical fiber to the oscillating laser head (1), which can realize the linear, circular, 8-shaped or ∞-shaped oscillation of the point ring laser.

Images