Laser-assisted helium arc penetration fusion welding method

Abstract

The invention discloses a laser-assisted helium arc penetration fusion welding method, and belongs to the technical field of welding. The problems that according to an existing paraxial laser-electric arc composite structure, the welding track is difficult to control, the energy coupling efficiency is low due to laser energy loss, and weld joint partial melting and undercut defects are caused due to uneven distribution of a welding temperature field due to a generated asymmetric heat source are solved. The welding method comprises the steps of 1, pretreatment; 2, after being focused by a focus lens, the laser is divided into three laser beams through a spectroscope, then the three laser beams are converged again through a plurality of reflectors, three fan-shaped light spots are formed on the surface of the to-be-welded plate after convergence, and finally the focal plane position of the laser is adjusted to be located on the surface of the to-be-welded plate; 3, setting welding current and arc voltage; and fourthly, laser is used for assisting helium arc penetration fusion welding. The method is used for laser-assisted helium arc penetration fusion welding.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of welding. BACKGROUND

[0002] Medium-thick plate aluminum alloy can meet the stringent requirements of extreme service environment on the strength and reliability of structural parts due to its excellent physical and chemical properties, and has irreplaceable application value in the manufacturing of key structural parts in aerospace. The welding quality directly determines the performance stability and service life of the structure, so efficient and reliable welding technology has become the core demand of the industry. At present, the main processes used in the field of medium-thick plate aluminum alloy welding are friction stir welding, electron beam welding, laser welding and TIG welding. Although friction stir welding can obtain a well-formed weld by precise process control, the equipment cost is high, and it is difficult to realize the welding of complex structures due to the limitation of rigid fixation requirements and three-dimensional trajectory motion accuracy. Electron beam welding relies on a vacuum environment for operation, and when welding large-size components, a large vacuum chamber is required, which increases the technical implementation difficulty and equipment cost simultaneously. In addition, due to the high reflectivity of aluminum alloy surface, single laser welding requires ultra-high power laser or vacuum environment support, which not only increases the technical cost, but also faces the problems of unstable keyhole, alloy element burning loss, etc. TIG welding has a shallow penetration, and the conventional argon arc process is only suitable for plates below 10 mm. When welding thick plates, a "base + cover" multi-pass welding process is required, which consumes a lot of filler material and has low efficiency. Moreover, the large heat input will cause serious welding deformation and grain coarsening problems. To solve the problem of insufficient penetration of TIG welding, the existing technology uses helium gas with high ionization energy as the protective gas to greatly improve the penetration by utilizing the heat flow concentration characteristics of helium arc. However, single helium arc TIG welding still faces the problems of unstable arc contraction and arc drift, which makes it difficult to control the consistency of weld formation. To solve the problem of arc stability, the existing technology uses laser-assisted helium arc TIG welding to generate a traction effect on the arc, effectively improving the welding quality. However, the traditional off-axis laser-arc coupling structure still has two major technical problems: First, in terms of spatial distribution of laser-arc, the traditional laser-arc composite welding uses laser as the main heat source to act almost vertically on the surface of the workpiece to be welded, and uses the arc as the auxiliary heat source located in front or behind the laser to improve the weld formation. Due to the plasma shielding effect, the energy coupling efficiency is low, and the "one front and one back" arrangement of laser and arc has strict limitations on the weld direction, making it difficult to deal with complex three-dimensional welds and difficult to automate. SUMMARY

[0003] This invention aims to address the problems of existing off-axis laser-arc composite structures, such as difficulty in controlling the welding trajectory, low energy coupling efficiency due to laser energy loss, and uneven welding temperature field distribution caused by asymmetric heat sources, resulting in weld defects such as partial melting and undercut. Therefore, it provides a laser-assisted helium arc deep penetration welding method.

[0004] A laser-assisted helium arc deep penetration welding method is performed according to the following steps:

[0005] 1. Pre-treat the weld area of ​​the aluminum alloy sheet to be welded to obtain the pre-treated sheet to be welded;

[0006] 2. The two pre-treated plates to be welded are joined together and placed on the welding platform in the laser-assisted helium arc deep penetration welding device. The tungsten electrode of the TIG welding torch is perpendicular to the surface of the plate to be welded. After the laser is focused by the focusing lens, it is split into three laser beams by the beam splitter. Then, the three laser beams are converged again by multiple reflectors. After convergence, three fan-shaped light spots are formed on the surface of the plate to be welded. The three fan-shaped light spots are distributed circumferentially along the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, forming the initial position. Then, the reflectors are adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded. After the movement is completed, the termination position is formed. Finally, the position of the laser focal plane is adjusted to be on the surface of the plate to be welded.

[0007] 3. Turn on the arc welding machine, set the welding current to 245A~305A, and then turn on the arc voltage controller and set the arc voltage to 12.5V~12.9V;

[0008] IV. Under the conditions of arc voltage of 12.5V~12.9V, welding current of 245A~305A, laser power of 1750W~2500W, welding speed of 10m / h~15m / h and helium flow rate of 5L / min~10L / min, laser-assisted helium arc deep penetration welding is used, and the weld is formed after natural cooling and solidification. This completes the laser-assisted helium arc deep penetration welding method.

[0009] The beneficial effects of this invention are:

[0010] This invention effectively solves existing problems in the welding of medium and heavy aluminum alloy plates through a laser-assisted helium arc deep penetration welding method, achieving a significant technological breakthrough. The specific effects of the invention are as follows:

[0011] 1. The laser-assisted helium arc deep penetration welding method proposed in this invention uses a helium arc as the main heat source perpendicular to the surface of the workpiece, and a laser as an auxiliary heat source incident from three directions. This effectively reduces the impact of plasma shielding on the laser, thereby improving energy coupling efficiency. The laser-assisted helium arc deep penetration welding method proposed in this invention can significantly increase penetration depth and improve welding efficiency. Utilizing the synergistic effect of the coaxial laser and helium arc, the welding energy density is significantly improved. Compared to the traditional TIG welding of medium-thick aluminum alloy plates, which requires beveling, this invention can adjust the arc characteristics by changing the laser spot distribution pattern, greatly increasing penetration depth. High-quality welding of medium-thick aluminum alloy plates can be achieved without beveling, reducing welding passes and filler material, significantly shortening welding time, and improving production efficiency.

[0012] 2. The laser-assisted helium arc deep penetration welding method proposed in this invention can improve welding stability and quality. The laser beam compresses the arc, effectively suppressing arc drift. While the laser energy distribution in the laser spot mode of this invention is also an asymmetric heat source, it allows for control of the welding temperature field distribution. This avoids the welding defects such as porosity, weld undercut, and uneven melting that are common in laser welding of medium-thick aluminum alloy plates and traditional laser-arc hybrid welding due to the presence of the laser keyhole. It is more conducive to forming smooth, clean, porosity-free, and crack-free high-quality welds, improving the mechanical properties and structural reliability of the joint, and meeting the stringent welding quality requirements of aerospace and other fields.

[0013] 3. The laser-assisted helium arc deep penetration welding method proposed in this invention offers easily controllable welding trajectories, expands the existing welding process window for medium-thick aluminum alloy plates, and exhibits high adaptability to complex joint types. This invention has a higher tolerance for fluctuations in welding process parameters, enabling flexible responses to the welding needs of medium-thick aluminum alloy plates with varying thicknesses and joint types. In the welding of large and complex structural components, compared to the traditional off-axis laser-arc hybrid welding mode, it better adapts to complex joint types, reduces welding difficulty, and ensures stable welding quality.

[0014] 4. The laser-assisted helium arc deep penetration welding method proposed in this invention can reduce equipment operating costs. It eliminates the need for a large vacuum chamber, simplifying equipment requirements and reducing technical difficulty and equipment investment costs. Simultaneously, its high-efficiency welding characteristics reduce energy consumption and material loss, further lowering operating costs and achieving an economical and reliable welding goal, thus promoting the wider application of medium-thick aluminum alloy plates in the industrial field. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the laser-assisted helium arc deep penetration welding device of the present invention;

[0016] Figure 2 This is a schematic diagram showing the initial positions and moving paths of the three fan-shaped light spots of the present invention; the dashed lines represent the moving paths.

[0017] Figure 3 The diagram shows the termination positions of the three fan-shaped light spots after movement, where (a) is a movement distance < 2.5 mm, (b) is a movement distance of 2.5 mm, (c) is a movement distance > 2.5 mm and < 3.077 mm, (d) is a movement distance of 3.077 mm, (e) is a movement distance of 3.6547 mm, and (f) is a movement distance > 3.6547 mm and ≤ 5 mm.

[0018] Figure 4 This is a surface morphology diagram of the welded joint in Example 1;

[0019] Figure 5 This is a cross-sectional topographic view of the welded joint in Example 1;

[0020] Figure 6 For comparison, see the surface morphology of the welded joint in Experiment 1;

[0021] Figure 7 For comparison, see the cross-sectional morphology of the welded joint in Experiment 1;

[0022] Figure 8 For comparison, see the surface morphology of the welded joint in Experiment 2;

[0023] Figure 9 For comparison, the cross-sectional morphology of the welded joint in Experiment 2 is shown. Detailed Implementation

[0024] Specific Implementation Method 1: This implementation method is a laser-assisted helium arc deep penetration welding method, which is carried out according to the following steps:

[0025] 1. Pre-treat the weld area of ​​the aluminum alloy sheet to be welded to obtain the pre-treated sheet to be welded;

[0026] 2. The two pre-treated plates to be welded are joined together and placed on the welding platform in the laser-assisted helium arc deep penetration welding device. The tungsten electrode of the TIG welding torch is perpendicular to the surface of the plate to be welded. After the laser is focused by the focusing lens, it is split into three laser beams by the beam splitter. Then, the three laser beams are converged again by multiple reflectors. After convergence, three fan-shaped light spots are formed on the surface of the plate to be welded. The three fan-shaped light spots are distributed circumferentially along the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, forming the initial position. Then, the reflectors are adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded. After the movement is completed, the termination position is formed. Finally, the position of the laser focal plane is adjusted to be on the surface of the plate to be welded.

[0027] 3. Turn on the arc welding machine, set the welding current to 245A~305A, and then turn on the arc voltage controller and set the arc voltage to 12.5V~12.9V;

[0028] IV. Under the conditions of arc voltage of 12.5V~12.9V, welding current of 245A~305A, laser power of 1750W~2500W, welding speed of 10m / h~15m / h and helium flow rate of 5L / min~10L / min, laser-assisted helium arc deep penetration welding is used, and the weld is formed after natural cooling and solidification. This completes the laser-assisted helium arc deep penetration welding method.

[0029] In this specific implementation method, step three involves using an arc voltage controller to stabilize the arc voltage during the welding process, ensuring stable laser-arc coupling.

[0030] The laser-assisted helium arc deep penetration welding method proposed in this specific embodiment uses a helium arc as the main heat source perpendicular to the surface of the workpiece to be welded, and a laser as an auxiliary heat source incident from three directions.

[0031] This specific implementation method is based on the TIG welding process for medium-thick aluminum alloy plates, and innovatively proposes a laser-assisted helium arc deep penetration welding method. By coaxially integrating the laser beam and the helium arc, efficient energy transmission and dynamic balance control of the molten pool are achieved, providing a solution that combines technological advancement and engineering economy for the manufacturing of medium-thick aluminum alloy components with high reliability requirements.

[0032] The beneficial effects of this embodiment are:

[0033] This embodiment effectively solves the existing problems in the field of welding medium and heavy aluminum alloy plates through laser-assisted helium arc deep penetration welding, achieving a significant technological breakthrough. The specific effects of the invention are as follows:

[0034] 1. The laser-assisted helium arc deep penetration welding method proposed in this embodiment uses a helium arc as the main heat source perpendicular to the surface of the workpiece to be welded, and a laser as an auxiliary heat source incident from three directions. This effectively reduces the impact of plasma shielding on the laser, thereby improving energy coupling efficiency. The laser-assisted helium arc deep penetration welding method proposed in this embodiment can significantly increase the penetration depth and improve welding efficiency. Utilizing the synergistic effect of the coaxial laser and helium arc, the welding energy density is significantly improved. Compared to the traditional TIG welding of medium-thick aluminum alloy plates, which requires beveling, this embodiment can adjust the arc characteristics by changing the spot distribution pattern, greatly increasing the penetration depth. High-quality welding of medium-thick aluminum alloy plates can be achieved without beveling, reducing the number of welding passes and filler material, significantly shortening welding time, and improving production efficiency.

[0035] 2. The laser-assisted helium arc deep penetration welding method proposed in this embodiment can improve welding stability and quality. The laser beam compresses the arc, effectively suppressing arc drift. While the laser energy distribution in this embodiment is also an asymmetric heat source, it allows for control of the welding temperature field distribution. This avoids the welding defects such as porosity, weld undercut, and uneven melting that are common in laser welding of medium-thick aluminum alloy plates and traditional laser-arc hybrid welding due to the presence of the laser keyhole. It is more conducive to forming smooth, clean, porosity-free, and crack-free high-quality welds, improving the mechanical properties and structural reliability of the joint, and meeting the stringent welding quality requirements of aerospace and other fields.

[0036] 3. The laser-assisted helium arc deep penetration welding method proposed in this embodiment offers easy control of the welding trajectory, expands the existing welding process window for medium-thick aluminum alloy plates, and exhibits high adaptability to complex joint types. This embodiment has a higher tolerance for fluctuations in welding process parameters, and can flexibly address the welding needs of medium-thick aluminum alloy plates with different thicknesses and joint types. In the welding of large and complex structural components, compared with the traditional off-axis laser-arc hybrid welding mode, it can better adapt to complex joint types, reduce welding difficulty, and ensure stable welding quality.

[0037] 4. The laser-assisted helium arc deep penetration welding method proposed in this embodiment can reduce equipment operating costs. It eliminates the need for a large vacuum chamber, simplifying equipment requirements and reducing technical difficulty and equipment investment costs. Simultaneously, its high-efficiency welding characteristics reduce energy consumption and material loss, further lowering operating costs and achieving an economical and reliable welding goal, thus promoting the wider application of medium-thick aluminum alloy plates in the industrial field.

[0038] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the aluminum alloy sheet to be welded in step one is made of 2219-T8 material and has a thickness of 6mm~20mm. Everything else is the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the pretreatment described in step one is surface mechanical polishing or acid / alkali washing. Everything else is the same as in Specific Implementation Method One or Two.

[0040] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the acid-base washing treatment is carried out according to the following steps: The aluminum alloy sheet to be welded is immersed in a 10%~15% NaOH solution for 5 to 10 minutes, then rinsed sequentially with water and anhydrous ethanol and dried to obtain an alkali-washed aluminum alloy sheet. The alkali-washed aluminum alloy sheet is then immersed in a 25%~35% HNO3 solution for 2 to 4 minutes, then rinsed sequentially with water and anhydrous ethanol and dried for later use. Welding is performed within 24 hours. Everything else is the same as in Specific Implementation Methods One to Three.

[0041] In this specific implementation method, step one involves alkali washing and acid washing of the weld area of ​​the aluminum alloy sheet before welding, followed by drying. Welding is then carried out within 24 hours to prevent defects such as porosity and inclusions from forming due to the presence of oxide film, oil, moisture, etc. during the welding process.

[0042] Specific implementation method five, combined with Figure 2 and 3 Specific Explanation: This embodiment differs from one of embodiments one to four in that: in step two, the three fan-shaped light spots are distributed circumferentially along the projection point of the TIG welding torch tungsten electrode on the surface of the workpiece to be welded, and are located in different orientations. The apex of the central corner of each fan-shaped light spot faces the projection point of the TIG welding torch tungsten electrode on the surface of the workpiece to be welded, forming the initial position. The distance between the fan edges of two adjacent fan-shaped spots at the initial position is 4.33 mm. Then, the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the TIG welding torch tungsten electrode on the surface of the workpiece to be welded. After the movement is completed, the termination position is formed. The movement distance between the termination position and the initial position of the three fan-shaped light spots is 0 mm to 5 mm. Finally, the laser focal plane position is adjusted to be on the surface of the workpiece to be welded. Everything else is the same as in embodiments one to four.

[0043] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step two, the lines connecting the vertices of the central angles of the three fan-shaped light spots at the initial position form an equilateral triangle; the fan-shaped angles of the fan-shaped light spots in step two are all 120°, and the diameter of the circles containing the fan-shaped spots is 2mm; in step two, the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded, and the termination position is formed after the movement is completed; or the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded, until the three fan-shaped light spots move to the projection point, and the termination position is formed after the movement is completed; or the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded, until the three fan-shaped light spots move past the projection point and then continue to move in a straight line, and the termination position is formed after the movement is completed. Everything else is the same as in Specific Implementation Methods One to Five.

[0044] Specific implementation method seven, combined with Figure 1 Specific description: This embodiment differs from one of the specific embodiments one to six in that: the laser-assisted helium arc deep penetration welding device described in step two consists of a laser 1, an arc welding machine 2, a laser-assisted helium arc welding head 3, and a welding platform 6; the welding platform 6 is set below the laser-assisted helium arc welding head 3.

[0045] The laser-assisted helium arc welding head 3 is internally equipped with a collimating lens 4-1, a beam expander 4-2, a focusing lens 4-3, a beam splitter 4-4, a reflecting mirror 4-5, and a TIG welding torch 5-1. The arc welding machine 2 is connected to the TIG welding torch 5-1 via a cable. The laser generated by the laser 1 passes through the collimating lens 4-1 and the beam expander 4-2 sequentially via an optical fiber, and is then focused by the focusing lens 4-3. It is then split into three laser beams by the beam splitter 4-4, and finally converged again by multiple reflecting mirrors 4-5, forming three fan-shaped light spots. Other aspects are the same as in specific embodiments one to six.

[0046] The laser-assisted helium arc welding head 3 described in this specific embodiment integrates a collimating lens 4-1, a beam expander 4-2, a focusing lens 4-3, a beam splitter 4-4, a reflecting mirror 4-5, and a TIG welding torch 5-1, which can ensure that the laser and the TIG welding torch 5-1 move synchronously during the welding process.

[0047] The beam splitter 4-4 and reflector 4-5 described in this specific embodiment can split and refocus the laser beam. The laser beam enters the laser-assisted helium arc welding head 3 through an optical fiber, passes through the collimating lens 4-1 and the beam expander 4-2 in sequence, is focused by the focusing lens 4-3, and is split into three by the beam splitter 4-4. Then, several reflectors 4-5 are used to focus the three laser beams at the position where the TIG welding torch 5-1 interacts with the workpiece to be welded.

[0048] The TIG welding torch 5-1 described in this specific embodiment is located inside the laser-assisted helium arc welding head 3 and is connected to the external arc welding machine 2 via a cable.

[0049] In this specific embodiment, the laser-assisted helium arc welding head 3 is mounted on a welding robot. During welding, the workpiece to be welded is placed on the welding platform 6, and the welding robot controls the laser-assisted helium arc welding head 3 to move along the planned path to complete the welding process.

[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the welding shielding gas cylinder 7 is connected to the laser-assisted helium arc welding head 3 via a shielding gas hose, and the shielding gas is blown out coaxially along the tungsten electrode of the TIG welding torch 5-1. Everything else is the same as Specific Implementation Methods One to Seven.

[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the arc voltage controller 8 is connected to the arc welding machine 2 via a cable. Otherwise, it is the same as Specific Implementation Methods One to Eight.

[0052] The arc voltage controller 8 described in this specific embodiment can ensure the stability of the arc voltage during welding and avoid adverse effects of the molten pool flow behavior on the arc.

[0053] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the laser-assisted helium arc welding head 3 is mounted on a welding robot. Everything else is the same as in Specific Implementation Methods One to Nine.

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

[0055] Example 1: This example uses the surfacing welding process on a piece of aluminum alloy sheet to be welded, in order to verify the performance effect.

[0056] A laser-assisted helium arc deep penetration welding method is performed according to the following steps:

[0057] 1. Pre-treat the weld area of ​​the aluminum alloy sheet to be welded to obtain the pre-treated sheet to be welded;

[0058] 2. The pre-treated plate to be welded is placed on the welding platform in the laser-assisted helium arc deep penetration welding device. The tungsten electrode of the TIG welding torch is perpendicular to the surface of the plate to be welded. After the laser is focused by the focusing lens, it is split into three laser beams by the beam splitter. Then, the three laser beams are re-converged by multiple reflectors, forming three fan-shaped spots on the surface of the plate to be welded. The three fan-shaped spots are distributed circumferentially along the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, and are located in different directions. The apex of the central corner of the fan-shaped spot faces the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, forming the initial position. The distance between the fan edges of two adjacent fan-shaped spots at the initial position is 4.33 mm. Then, the reflectors are adjusted so that the three fan-shaped spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, until the three fan-shaped spots move to the projection point. After the movement ends, the termination position is formed. The distance moved from the initial position to the termination position of the three fan-shaped spots is 3.077 mm. Figure 3 (d) Finally, adjust the laser focal plane position to be on the surface of the plate to be welded;

[0059] The lines connecting the vertices of the central angles of the three fan-shaped light spots at the initial position form an equilateral triangle; the fan angles of the fan-shaped light spots are all 120°, and the diameter of the circles containing the fan-shaped spots is 2mm.

[0060] 3. Turn on the arc welding machine, set the welding current to 260A, and then turn on the arc voltage controller and set the arc voltage to 12.6V;

[0061] IV. Under the conditions of an arc voltage of 12.6V, a welding current of 260A, a laser power of 2000W, a welding speed of 12.5m / h, and a helium flow rate of 10L / min, laser-assisted helium arc deep penetration welding is used. After natural cooling and solidification, a weld joint is formed, thus completing the laser-assisted helium arc deep penetration welding method.

[0062] The aluminum alloy sheet to be welded mentioned in step one is made of 2219-T8 and has dimensions of 300mm×100mm×13mm.

[0063] The pretreatment mentioned in step one is an acid-base washing treatment, which is carried out in the following steps: the aluminum alloy sheet to be welded is immersed in a 10% NaOH solution for 10 minutes, then rinsed with water and anhydrous ethanol in sequence and dried to obtain an alkaline-washed aluminum alloy sheet. The alkaline-washed aluminum alloy sheet is then immersed in a 30% HNO3 solution for 4 minutes, then rinsed with water and anhydrous ethanol in sequence and dried for later use, and welding is carried out within 24 hours.

[0064] The laser-assisted helium arc deep penetration welding device described in step two consists of a laser 1, an arc welding machine 2, a laser-assisted helium arc welding head 3, and a welding platform 6; the welding platform 6 is set below the laser-assisted helium arc welding head 3.

[0065] The laser-assisted helium arc welding head 3 is equipped with a collimating lens 4-1, a beam expander 4-2, a focusing lens 4-3, a beam splitter 4-4, a reflector 4-5, and a TIG welding torch 5-1. The arc welding machine 2 is connected to the TIG welding torch 5-1 via a cable. The laser generated by the laser 1 passes through the collimating lens 4-1 and the beam expander 4-2 in sequence via an optical fiber, and then is focused by the focusing lens 4-3. After being split into three laser beams by the beam splitter 4-4, the three laser beams are finally converged again by multiple reflectors 4-5 to form three fan-shaped light spots.

[0066] The welding shielding gas cylinder 7 is connected to the laser-assisted helium arc welding head 3 via a shielding gas hose, and the shielding gas is blown out coaxially along the tungsten electrode of the TIG welding torch 5-1.

[0067] The arc voltage controller 8 is connected to the arc welding machine 2 via a cable.

[0068] The laser-assisted helium arc welding head 3 is mounted on a KUKA 6-axis robot.

[0069] In this embodiment, the laser-assisted helium arc deep penetration welding method uses a helium arc as the main heat source perpendicular to the surface of the workpiece to be welded, and a laser as an auxiliary heat source incident from three directions.

[0070] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the laser power in step four is 0W. Everything else is the same as in Example 1.

[0071] Comparative Experiment 2: This comparative experiment differs from Example 1 in that the laser power in step four is 1500W. Everything else is the same as in Example 1.

[0072] Figure 4 The figure shows the surface morphology of the welded joint in Example 1. As can be seen from the figure, this example can obtain a full-penetration weld with a bright surface, no porosity, no cracks, and no oxidation, and no defects such as weld undercut or off-center melting.

[0073] Figure 5 This is a cross-sectional topographic view of the welded joint in Example 1. As can be seen from the figure, this example yields a high-quality weld with a tightly packed microstructure and no obvious porosity, pores, microcracks, weld undercut, or other welding defects.

[0074] According to the national standard GB / T 228.1-2021, the welded joint of Example 1 was processed into a full-size tensile specimen with flush top and bottom. Using an Instron 8862 electronic universal tensile testing machine, a tensile test was conducted at a tensile rate of 1 mm / min. The tensile strength of the welded joint was 277.2 MPa, and the elongation was 4.74%. The mechanical properties of the 2219 aluminum alloy base material were tested and found to be a tensile strength of 446.4 MPa and an elongation of 10.4%. Therefore, the tensile strength and elongation of the welded joint tensile specimen can reach 62.1% and 45.6% of those of the base material, respectively.

[0075] Figure 6 To compare the surface morphology of the welded joint in Experiment 1; as shown in the figure, when the laser power is 0W, that is, when it is single arc welding, the weld cannot be fully penetrated.

[0076] Figure 7 The figure shows the cross-sectional morphology of the welded joint in Experiment 1 for comparison. As can be seen from the figure, combined with the results of Example 1, the addition of laser significantly increases the weld penetration.

[0077] Figure 8 To compare the surface morphology of the welded joint in Experiment 2; as shown in the figure, the back of the weld shows a state of penetration but incomplete formation, indicating that although the heat input during the welding process under this parameter is sufficient to penetrate the weld, it is not sufficient.

[0078] Figure 9 The figure shows the cross-sectional morphology of the welded joint in Experiment 2 for comparison. As can be seen from the figure, combined with the results of Example 1, it indicates that as the laser power increases, the degree of depression on the weld surface gradually increases, and the back of the weld gradually becomes fuller.

[0079] Under the same tensile strength test conditions as in Example 1, the tensile strength of the welded joint in Comparative Experiment 2 was 269 MPa, and the elongation was 4.6%. However, due to insufficient weld penetration, the robustness of the joint's tensile strength was poor.

Claims

1. A laser-assisted helium arc deep penetration welding method, characterized in that... It is done in the following steps:

1. Pre-treat the weld area of ​​the aluminum alloy sheet to be welded to obtain the pre-treated sheet to be welded; 2. The two pre-treated plates to be welded are joined together and placed on the welding platform in the laser-assisted helium arc deep penetration welding device. The tungsten electrode of the TIG welding torch is perpendicular to the surface of the plate to be welded. After the laser is focused by the focusing lens, it is split into three laser beams by the beam splitter. Then, the three laser beams are converged again by multiple reflectors. After convergence, three fan-shaped light spots are formed on the surface of the plate to be welded. The three fan-shaped light spots are distributed circumferentially along the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded, forming the initial position. Then, the reflectors are adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the plate to be welded. After the movement is completed, the termination position is formed. Finally, the position of the laser focal plane is adjusted to be on the surface of the plate to be welded.

3. Turn on the arc welding machine, set the welding current to 245A~305A, and then turn on the arc voltage controller and set the arc voltage to 12.5V~12.9V; IV. Under the conditions of arc voltage of 12.5V~12.9V, welding current of 245A~305A, laser power of 1750W~2500W, welding speed of 10m / h~15m / h and helium flow rate of 5L / min~10L / min, laser-assisted helium arc deep penetration welding is used, and the weld is formed after natural cooling and solidification. This completes the laser-assisted helium arc deep penetration welding method.

2. The laser-assisted helium arc deep penetration welding method according to claim 1, characterized in that... The aluminum alloy sheet to be welded mentioned in step one is made of 2219-T8 material and has a thickness of 6mm~20mm.

3. The laser-assisted helium arc deep penetration welding method according to claim 1, characterized in that... The pretreatment mentioned in step one is surface mechanical polishing or acid / alkali washing.

4. The laser-assisted helium arc deep penetration welding method according to claim 3, characterized in that... The acid-base washing treatment is carried out in the following steps: the aluminum alloy sheet to be welded is immersed in a 10%~15% NaOH solution for 5min~10min, then rinsed with water and anhydrous ethanol in sequence and dried to obtain an alkaline-washed aluminum alloy sheet. The alkaline-washed aluminum alloy sheet is then immersed in a 25%~35% HNO3 solution for 2min~4min, then rinsed with water and anhydrous ethanol in sequence and dried for later use. Welding is carried out within 24 hours.

5. The laser-assisted helium arc deep penetration welding method according to claim 1, characterized in that... In step two, three fan-shaped light spots are distributed circumferentially along the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded, and are located in different directions. The apex of the central corner of the fan-shaped light spot faces the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded, forming the initial position. The distance between the fan edges of two adjacent fan-shaped spots at the initial position is 4.33mm. Then, the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the TIG welding torch tungsten electrode on the surface of the substrate to be welded. After the movement is completed, the termination position is formed. The movement distance between the termination position and the initial position of the three fan-shaped light spots is 0mm~5mm. Finally, the laser focal plane position is adjusted to be on the surface of the substrate to be welded.

6. The laser-assisted helium arc deep penetration welding method according to claim 5, characterized in that... In step two, the lines connecting the vertices of the central angles of the three fan-shaped light spots at the initial position form an equilateral triangle; the fan angles of the fan-shaped light spots mentioned in step two are all 120°, and the diameter of the circles containing the fan-shaped light spots is 2mm; in step two, the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the substrate to be welded, and the termination position is formed after the movement is completed; or the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the substrate to be welded, until the three fan-shaped light spots move to the projection point, and the termination position is formed after the movement is completed; or the reflector is adjusted so that the three fan-shaped light spots move in a straight line from the initial position toward the projection point of the tungsten electrode of the TIG welding torch on the surface of the substrate to be welded, until the three fan-shaped light spots move past the projection point and then continue to move in a straight line, and the termination position is formed after the movement is completed.

7. The laser-assisted helium arc deep penetration welding method according to claim 1, characterized in that... The laser-assisted helium arc deep penetration welding device described in step two consists of a laser (1), an arc welding machine (2), a laser-assisted helium arc welding head (3), and a welding platform (6); the welding platform (6) is set below the laser-assisted helium arc welding head (3); The laser-assisted helium arc welding head (3) is equipped with a collimating lens (4-1), a beam expander (4-2), a focusing lens (4-3), a beam splitter (4-4), a reflecting mirror (4-5), and a TIG welding torch (5-1). The arc welding machine (2) is connected to the TIG welding torch (5-1) via a cable. The laser generated by the laser (1) passes through the collimating lens (4-1) and the beam expander (4-2) in sequence via an optical fiber. After being focused by the focusing lens (4-3), it is split into three laser beams by the beam splitter (4-4). Finally, the three laser beams are re-converged by multiple reflecting mirrors (4-5) to form three fan-shaped light spots.

8. The laser-assisted helium arc deep penetration welding method according to claim 7, characterized in that... The welding shielding gas cylinder (7) is connected to the laser-assisted helium arc welding head (3) through the shielding gas hose, and the shielding gas is blown out coaxially along the tungsten electrode of the TIG welding torch (5-1).

9. A laser-assisted helium arc deep penetration welding method according to claim 7, characterized in that... The arc voltage controller (8) is connected to the arc welding machine (2) via a cable.

10. A laser-assisted helium arc deep penetration welding method according to claim 7, characterized in that... The laser-assisted helium arc welding head (3) is mounted on a welding robot.

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