Laser pulse welding method for thin-wall aluminum alloy butt joint

Abstract

The invention relates to the technical field of laser welding, in particular to a thin-wall aluminum alloy butt joint laser pulse welding method which comprises the following steps of part pretreatment, part assembly, back shielding gas filling, welding parameter adjustment and welding, and inspection and treatment after welding. The energy density of 100-150J / mm is taken as a target reference, the peak duration is reversely limited to be within 8-12ms, and the corresponding peak power is matched, so that the energy of laser pulse acting on a welding area is concentrated and is not overloaded, the burn-through defect caused by too high local temperature of the thin-wall aluminum alloy is avoided, the welding seam forming integrity is guaranteed, and the cold crack problem is solved. According to the method, the basic value power is increased to 600-800 W, meanwhile, the pulse frequency is adjusted to 50-80 Hz, the continuous heat preservation effect is provided for the molten pool by increasing the basic value power, the pulse interval is shortened in cooperation with the high pulse frequency, the cooling speed of the molten pool is slowed down, thermal stress accumulation is reduced, the cold crack generation probability can be greatly reduced, and the mechanical stability of a connector is improved.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to a laser pulse welding method for thin-walled aluminum alloy butt joints. Background Technology

[0002] The laser pulse welding method for thin-walled aluminum alloy butt joints uses a pulsed laser as a heat source, applied to the joint. Its core function is to precisely control the heat input through pulsed energy output, reducing deformation and burn-through problems that are prone to occur in thin-walled aluminum alloys due to their rapid thermal conductivity and high coefficient of linear expansion, thus ensuring the quality of the joint formation. During welding, the laser energy is concentrated on the butt joint gap, causing the local metal to melt rapidly and form a molten pool. The molten pool cools and solidifies during the pulse interval, achieving the joint connection. At the same time, it reduces the heat-affected zone and minimizes the degradation of the joint's mechanical properties. This method can adapt to the butt joint requirements of thin-walled aluminum alloys of different thicknesses. By adjusting parameters such as pulse frequency and energy density, it ensures that the weld at the joint is uniform and meets the strength requirements, satisfying the high-precision and high-quality connection needs of thin-walled aluminum alloy components in aerospace, automotive, and other fields, thereby improving the overall reliability and service life of the components.

[0003] However, during the implementation of the above technical solution, at least the following technical problems were discovered: Current laser pulse welding technology for thin-walled aluminum alloy butt joints does not use quantitative formulas to correlate key parameters such as peak power, peak duration, base power, pulse frequency, and welding speed. Instead, it relies solely on operator experience for setting these parameters. When the peak pulse power exceeds 1500W or the peak duration exceeds 15ms, the thin-walled aluminum alloy, due to its rapid thermal conductivity, experiences excessively high local energy density, making it prone to burn-through. When the base power is below 500W or the pulse frequency is below 30Hz, the molten pool cools too quickly within the pulse interval, especially for 6-series aluminum alloys, easily leading to cold cracks. Furthermore, the existing technology does not balance the average power and welding speed, and adjusting parameters can easily cause an imbalance in overall heat input, resulting in either overheating deformation or rapid cooling and cracking. This severely affects the welding quality and joint mechanical properties, failing to meet the high-precision welding requirements of thin-walled aluminum alloy components in aerospace, automotive, and other fields. Summary of the Invention

[0004] Technical problems to be solved: Existing laser pulse welding technology for thin-walled aluminum alloy butt joints does not use quantitative formulas to correlate key parameters such as peak power, peak duration, base power, pulse frequency, and welding speed. Instead, it relies solely on operator experience for setting parameters. When the peak pulse power exceeds 1500W or the peak duration exceeds 15ms, the thin-walled aluminum alloy, due to its rapid thermal conductivity, experiences excessively high local energy density, making it prone to burn-through. When the base power is below 500W or the pulse frequency is below 30Hz, the molten pool cools too quickly within the pulse interval, especially for 6-series aluminum alloys, easily leading to cold cracks. Furthermore, existing technology does not balance the average power and welding speed, and adjusting parameters can easily lead to an imbalance in overall heat input, resulting in either overheating deformation or rapid cooling and cracking. This severely affects the welding quality and joint mechanical properties, failing to meet the high-precision welding requirements of thin-walled aluminum alloy components in aerospace, automotive, and other fields.

[0005] To address the shortcomings of existing technologies, this invention provides a laser pulse welding method for thin-walled aluminum alloy butt joints, thereby solving the technical problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A laser pulse welding method for thin-walled aluminum alloy butt joints includes the following steps: S1: Part pretreatment. First, the aluminum alloy parts are pickled and degreased to remove surface impurities and oil. Then, the areas to be welded are polished with a wire brush or cleaned with a laser. When using laser cleaning, the average laser power should be set to 160-200W, the pulse frequency to 90-120Hz, and the polishing width should be no less than 15mm until the metal luster is exposed. Finally, the polished areas are cleaned with anhydrous ethanol or acetone to remove residual impurities. S2: Parts assembly: The parts to be welded are precisely assembled using positioning clamps and then clamped onto the rotary device of the laser welding machine. During assembly, the joint thickness is controlled to be 1±0.1mm, the misalignment is ≤0.1mm, and the joint gap is ≤0.1mm. S3: Back protection gas filling. Fill the cavity with 99.99% high-purity argon gas as back protection gas. The pressure of the protection gas is 0.1-0.5MPa and the gas flow rate is 5-10L / min. Back protection gas needs to be filled for 10-15 minutes before welding to purge the air inside the cavity. A vent hole is left at one end of the part to ensure gas flow. S4: Adjust welding parameters and start welding. First, adjust the laser angle to 5°-9° with the workpiece normal, and set a defocusing amount of +4-+6mm to ensure a spot diameter of 0.3-0.45mm. At the same time, adjust the direction and flow rate of the high-purity argon protective gas. First, accurately measure the actual spot diameter. Based on the energy density formula, set the target value to 100-150J / mm². Based on this, control the peak duration to 8-12ms and adjust the peak power to prevent burn-through. Then, increase the base power to 600-800W and adjust the pulse frequency to 50-80Hz to optimize the thermal cycle and prevent cold cracking. Finally, combine the average power and line energy formula to increase the welding speed to 30-50mm / s to balance the heat input. After confirming the parameters, start welding according to the preset trajectory. S5: Post-weld inspection and treatment. After removing the tooling, inspect the forming quality of the front and back of the weld, and check for defects such as pores and cracks. Use grinding tools to grind the oxide layer on the surface of the weld.

[0007] In one possible implementation, the energy density formula in step S4 is: = ; in, Let Pp be the energy density of the laser pulse acting on the workpiece surface, tp be the peak power of the laser pulse, d be the peak duration of the laser pulse, and d be the diameter of the laser spot formed on the workpiece surface.

[0008] In one possible implementation, in step S4, the target energy density is determined using the energy density formula. After calculating the measured spot diameter d, the maximum allowable energy of a single pulse is determined. Based on this, the peak power, Pp, and peak duration tp are set or adjusted to ensure that Pp × tp ≤ .

[0009] In one possible implementation, the formula for calculating the average power in step S4 is: ; Where Pavg is the average output power during the laser welding process, Pp is the peak power, tp is the peak duration, Pb is the base power, tb is the base duration, and T is the pulse period.

[0010] In one possible implementation, the pulse period T is related to the pulse frequency f as T(ms) = 1 / f(Hz) * 1000, and the base duration tb is related to the pulse period T and the peak duration tp as tb(ms) = T(ms) - tp(ms).

[0011] In one possible implementation, the base power Pb is set to 600-800W and the pulse frequency f is set to 50-80Hz.

[0012] In one possible implementation, in step S4, the formula for calculating the line energy is: = ; in, Pavg represents the total energy input per unit length of weld, Pavg is the average power, and v is the welding speed.

[0013] In one possible implementation, after increasing the average power Pavg by increasing the base power Pb and the pulse frequency f in step S4, the heat input is maintained by increasing the welding speed v to 30-50 mm / s. .

[0014] In one possible implementation, in step S4, the waveform of the laser pulse is a square wave.

[0015] In one possible implementation, in step S4, the flow rate of the front protective gas is 15-25 L / min.

[0016] Beneficial effects compared to existing technologies: 1. In this solution, to address the burn-through problem, the present invention first accurately measures the actual laser spot diameter, using an energy density of 100-150 J / mm² as the target benchmark, and then limits the peak duration to within 8-12 ms, matching the corresponding peak power. This ensures that the energy of the laser pulse acting on the welding area is concentrated and not overloaded, avoiding burn-through defects in thin-walled aluminum alloys due to excessively high local temperatures, and ensuring the integrity of the weld formation; 2. In this solution, to address the problem of cold cracking, the present invention increases the base power to 600-800W and adjusts the pulse frequency to 50-80Hz. By increasing the base power, a continuous "heat preservation" effect is provided for the molten pool. Combined with a higher pulse frequency to shorten the pulse interval, the cooling rate of the molten pool can be slowed down, reducing the accumulation of thermal stress. Especially for 6-series aluminum alloys, this can significantly reduce the probability of cold cracking and improve the mechanical stability of the joint. 3. In this solution, to avoid overall heat input imbalance caused by parameter adjustments, the welding speed is optimized to 30-50 mm / s to balance the total heat input. This setting prevents excessive heat input from causing part deformation and ensures sufficient solidification and fusion of the molten pool, achieving high-quality welding with "no burn-through, no cold cracks, and no deformation". This invention can significantly reduce the welding defect rate of thin-walled aluminum alloy butt joints, greatly improve key performance indicators such as weld tensile strength and sealing performance, and can stably achieve high-precision welding without relying on operator experience, meeting the stringent quality requirements of thin-walled aluminum alloy components in high-value-added fields. Attached Figure Description

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0019] To more clearly illustrate the overall concept of the invention, a detailed explanation is provided below with reference to the accompanying drawings.

[0020] In the description of the invention, it should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise expressly specified and limited, the first feature "on" or "below" the second feature may be in direct contact with the first and second features, or indirect contact through an intermediate medium. In the description of this specification, references to terms such as "a solution," "some solutions," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that solution or example is included in at least one solution or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same solution or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more solutions or examples; The technical solution in this application embodiment is to solve the problems mentioned in the background art, and the overall idea is as follows: Example:

[0024] Please refer to Figure 1 As shown in the figure, this embodiment introduces a laser pulse welding method for thin-walled aluminum alloy butt joints, including the following steps: S1: Part pretreatment. First, the aluminum alloy parts are pickled and degreased to remove surface impurities and oil. Then, the areas to be welded are polished with a wire brush or cleaned with a laser. When using laser cleaning, the average laser power should be set to 160-200W, the pulse frequency to 90-120Hz, and the polishing width should be no less than 15mm until the metal luster is exposed. Finally, the polished areas are cleaned with anhydrous ethanol or acetone to remove residual impurities. S2: Parts assembly: The parts to be welded are precisely assembled using positioning clamps and then clamped onto the rotary device of the laser welding machine. During assembly, the butt joint thickness is controlled to be 1±0.1mm, the misalignment is ≤0.1mm, and the butt joint gap is ≤0.1mm to ensure welding quality. S3: Back protection gas filling. Fill the cavity with 99.99% high-purity argon gas as back protection gas. The pressure of the protection gas is 0.1-0.5MPa and the gas flow rate is 5-10L / min. Back protection gas needs to be filled for 10-15 minutes before welding to purge the air inside the cavity. A vent hole is left at one end of the part to ensure gas flow. S4: Adjust welding parameters and start welding. First, adjust the laser angle to 5°-9° with the workpiece normal, and set a defocusing amount of +4-+6mm to ensure a spot diameter of 0.3-0.45mm. At the same time, adjust the direction and flow rate of the high-purity argon protective gas. First, accurately measure the actual spot diameter. Based on the energy density formula, set the target value to 100-150J / mm². Based on this, control the peak duration to 8-12ms and adjust the peak power to prevent burn-through. Then, increase the base power to 600-800W and adjust the pulse frequency to 50-80Hz to optimize the thermal cycle and prevent cold cracking. Finally, combine the average power and line energy formula to increase the welding speed to 30-50mm / s to balance the heat input. After confirming the parameters, start welding according to the preset trajectory. S5: Post-weld inspection and treatment. After removing the tooling, inspect the forming quality of the front and back of the weld, and check for defects such as pores and cracks. Use grinding tools to grind the oxide layer on the surface of the weld to obtain a good appearance and performance, so that the weld can better fuse with the base material.

[0025] In step S4, the energy density formula is: = ; Let Pp be the energy density of the laser pulse acting on the workpiece surface, tp be the peak power of the laser pulse, d be the peak duration of the laser pulse, and d be the diameter of the laser spot formed on the workpiece surface.

[0026] By using the energy density formula, the target energy density is determined. After calculating the measured spot diameter d, the maximum allowable energy of a single pulse is determined. Based on this, the peak power, Pp, and peak duration tp are set or adjusted to ensure that Pp × tp ≤ .

[0027] The formula for calculating average power is: ; Where Pavg is the average output power during laser welding, Pp is the peak power, tp is the peak duration, Pb is the base power, tb is the base duration, and T is the pulse period. First, the actual laser spot diameter is accurately measured, and an energy density of 100-150 J / mm² is used as the target benchmark. The peak duration is then limited to 8-12 ms, and the corresponding peak power is matched to ensure that the energy of the laser pulse acting on the welding area is concentrated and not overloaded, avoiding burn-through defects caused by excessive local temperature in thin-walled aluminum alloys, and ensuring the integrity of the weld formation.

[0028] The relationship between the pulse period T and the pulse frequency f is T(ms) = 1 / f(Hz) * 1000. The relationship between the base duration tb and the pulse period T and peak duration tp is tb(ms) = T(ms) - tp(ms). By setting the base power Pb to 600-800W and the pulse frequency f to 50-80Hz, the average power Pavg is increased, thereby optimizing the thermal cycle of the molten pool, reducing the cooling rate, and preventing cold cracking.

[0029] In step S4, the formula for calculating the linear energy is: = ; in, Pavg represents the total energy input per unit length of weld, Pavg is the average power, and v is the welding speed.

[0030] In step S4, after increasing the average power Pavg by increasing the base power Pb and the pulse frequency f, the heat input is maintained by increasing the welding speed v to 30-50 mm / s. Within a preset and reasonable range, to avoid overall overheating and deformation of the weld, the base power is increased to 600-800W, and the pulse frequency is adjusted to 50-80Hz. By increasing the base power, a continuous "heat preservation" effect is provided for the molten pool. Combined with a higher pulse frequency to shorten the pulse interval, the cooling rate of the molten pool is slowed down, and the accumulation of thermal stress is reduced. Especially for 6-series aluminum alloys, this can significantly reduce the probability of cold cracking and improve the mechanical stability of the joint.

[0031] In step S4, the waveform of the laser pulse is a square wave.

[0032] In step S4, the flow rate of the protective gas on the front is 15-25 L / min. By optimizing the welding speed to 30-50 mm / s, the total heat input is balanced, which not only prevents the deformation of the parts due to excessive heat input, but also ensures that the molten pool is fully solidified and fused, achieving high-quality welding with "no burn-through, no cold cracks, and no deformation". This invention significantly reduces the welding defect rate of thin-walled aluminum alloy butt joints, and greatly improves key performance indicators such as weld tensile strength and sealing performance. High-precision welding can be stably achieved without relying on the operator's experience, fully meeting the stringent quality requirements of thin-walled aluminum alloy components in high-value-added fields.

[0033] Working principle: The first step is to pickle and degrease the thin-walled aluminum alloy parts to remove impurities and oil stains from the surface, so as to prevent impurities from entering the molten pool during welding and affecting the weld quality. Next, for the area to be welded, choose to grind with a wire brush or laser cleaning. When laser cleaning, set the average power to 160-200W and the pulse frequency to 90-120Hz, and ensure that the grinding width is not less than 15mm until the area to be welded shows a metallic luster, thoroughly removing the dense oxide film that is easy to form on the surface of aluminum alloy. Finally, wipe the ground area with anhydrous ethanol or acetone to remove residual debris and cleaning agents, ensuring that the surface to be welded is clean. The second step involves using positioning clamps to assemble two thin-walled aluminum alloy parts to be welded together. The assembled parts are then clamped onto the rotary device of the laser welding machine. During the assembly process, the butt joint thickness is strictly controlled to be 1±0.1mm, the misalignment of the butt joint does not exceed 0.1mm, and the butt joint gap does not exceed 0.1mm. Through precise assembly and fixing, defects such as uneven melting and incomplete penetration during welding are avoided due to misalignment of parts or excessive gaps, thus providing a stable structural foundation for subsequent welding. The third step is to fill the welding cavity with high-purity argon gas (99.99% purity) as a back shielding gas, adjust the shielding gas pressure to 0.1-0.5MPa, and control the gas flow rate at 5-10L / min. Fill the back shielding gas 10-15 minutes before welding begins, and leave a vent at one end of the part to ensure that the air in the cavity is fully discharged, forming a stable inert gas atmosphere. This prevents the molten pool metal from reacting with oxygen and nitrogen in the air during welding, avoiding the formation of oxide inclusions and brittle phases, and ensuring the back-side forming quality and mechanical properties of the weld. The fourth step involves adjusting the laser angle so that the laser beam incident angle is 5°-9° to the workpiece normal, and setting a defocusing amount of +4-+6mm to ensure that the laser forms a spot diameter of 0.3-0.45mm on the workpiece surface. Simultaneously, the direction and flow rate of the high-purity argon protective gas on the front are adjusted (flow rate controlled at 15-25L / min) to create double protection on both the front and back sides. Then, the actual spot diameter is precisely measured, aiming for an energy density of 100-150J / mm², and the laser pulse peak duration is controlled at 8-12ms, matched with an appropriate peak power to avoid localized localization. Excessive energy can cause thin-walled aluminum alloys to burn through. To address this, the base power is increased to 600-800W and the pulse frequency is adjusted to 50-80Hz. By increasing the base power, the molten pool is continuously kept warm. The higher pulse frequency shortens the pulse interval, slowing down the cooling rate of the molten pool, reducing thermal stress accumulation, and preventing cold cracks. Finally, the welding speed is adjusted to 30-50mm / s to balance the overall heat input and prevent the parts from overheating and deforming. After confirming that all parameters are correct, the laser welding machine is started, and welding is performed according to the preset weld seam trajectory, causing the metal in the area to be welded to melt and solidify to form a weld seam.

[0034] Fifth, after welding is completed, remove the tooling fixtures and first visually inspect the forming quality of the front and back of the weld to check for obvious defects such as porosity and cracks. If defects are found, it is necessary to assess whether rework is required. If the forming is good, use a grinding tool to grind the oxide layer on the surface of the weld to remove surface oxide impurities, making the weld appearance smoother. At the same time, it enhances the fusion between the weld and the base material, further improving the mechanical properties and corrosion resistance of the joint, and ensuring that the welded thin-walled aluminum alloy butt joint meets the usage requirements.

[0035] Finally, it should be noted that the basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification, and therefore remain within the spirit and scope of the exemplary embodiments of this specification. Furthermore, this specification uses specific terms to describe embodiments of this specification. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined. Moreover, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods of this specification.

Claims

1. A laser pulse welding method for thin-walled aluminum alloy butt joints, characterized in that, Includes the following steps: S1: Part pretreatment. First, the aluminum alloy parts are pickled and degreased to remove surface impurities and oil. Then, the areas to be welded are polished with a wire brush or cleaned with a laser. When using laser cleaning, the average laser power should be set to 160-200W, the pulse frequency to 90-120Hz, and the polishing width should be no less than 15mm until the metal luster is exposed. Finally, the polished areas are cleaned with anhydrous ethanol or acetone to remove residual impurities. S2: Parts assembly: The parts to be welded are precisely assembled using positioning clamps and then clamped onto the rotary device of the laser welding machine. During assembly, the joint thickness is controlled to be 1±0.1mm, the misalignment is ≤0.1mm, and the joint gap is ≤0.1mm. S3: Back protection gas filling. Fill the cavity with 99.99% high-purity argon gas as back protection gas. The pressure of the protection gas is 0.1-0.5MPa and the gas flow rate is 5-10L / min. Back protection gas needs to be filled for 10-15 minutes before welding to purge the air inside the cavity. A vent hole is left at one end of the part to ensure gas flow. S4: Adjust welding parameters and start welding. First, adjust the laser angle to 5°-9° with the workpiece normal, and set a defocusing amount of +4-+6mm to ensure a spot diameter of 0.3-0.45mm. At the same time, adjust the direction and flow rate of the high-purity argon protective gas. First, accurately measure the actual spot diameter. Based on the energy density formula, set the target value to 100-150J / mm². Based on this, control the peak duration to 8-12ms and adjust the peak power to prevent burn-through. Then, increase the base power to 600-800W and adjust the pulse frequency to 50-80Hz to optimize the thermal cycle and prevent cold cracking. Finally, combine the average power and line energy formula to increase the welding speed to 30-50mm / s to balance the heat input. After confirming the parameters, start welding according to the preset trajectory. S5: Post-weld inspection and treatment. After removing the tooling, inspect the forming quality of the front and back of the weld, and check for defects such as pores and cracks. Use grinding tools to grind the oxide layer on the surface of the weld.

2. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the energy density formula is: = ； in, Let Pp be the energy density of the laser pulse acting on the workpiece surface, tp be the peak power of the laser pulse, d be the peak duration of the laser pulse, and d be the diameter of the laser spot formed on the workpiece surface.

3. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the target energy density is determined using the energy density formula. After calculating the measured spot diameter d, the maximum allowable energy of a single pulse is determined. Based on this, the peak power, Pp, and peak duration tp are set or adjusted to ensure that Pp × tp ≤ .

4. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the formula for calculating the average power is: ； Where Pavg is the average output power during the laser welding process, Pp is the peak power, tp is the peak duration, Pb is the base power, tb is the base duration, and T is the pulse period.

5. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 4, characterized in that, The relationship between the pulse period T and the pulse frequency f is T(ms) = 1 / f(Hz) * 1000, and the relationship between the base duration tb and the pulse period T and the peak duration tp is tb(ms) = T(ms) - tp(ms).

6. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 4, characterized in that, By setting the base power Pb to 600-800W and the pulse frequency f to 50-80Hz.

7. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the formula for calculating the linear energy is: = ; in, Pavg represents the total energy input per unit length of weld, Pavg is the average power, and v is the welding speed.

8. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, after increasing the average power Pavg by increasing the base power Pb and the pulse frequency f, the heat input is maintained by increasing the welding speed v to 30-50 mm / s. .

9. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the waveform of the laser pulse is a square wave.

10. The laser pulse welding method for thin-walled aluminum alloy butt joints as described in claim 1, characterized in that, In step S4, the flow rate of the front protective gas is 15-25 L / min.

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