A method for laser welding of ultra-thin stainless steel foils

Abstract

This invention discloses a laser welding method for ultrathin stainless steel foil, belonging to the field of high-energy beam welding. It enables the laser welding of 0.05~0.1mm ultrathin stainless steel foil to irregularly shaped curved surfaces, producing a smooth weld surface with a seamless transition to the substrate, free from oxidation and incomplete welding defects, and exhibiting excellent sealing properties. This invention avoids the problems of incomplete welding, poor sealing, and poor welding quality for irregularly shaped curved and complex structures that are common in existing laser welding methods for ultrathin stainless steel foil, thus improving welding quality.

Description

Technical Field

[0001] This invention relates to the field of high-energy beam welding, and more particularly to a laser welding method for ultrathin stainless steel foil. Background Technology

[0002] With the rapid development of my country's aerospace industry, components are increasingly trending towards lightweight and complex designs, leading to the widespread application of ultra-thin structural units, many of which have complex cross-sections. Currently, ultra-thin structures are mostly welded using ultrafast lasers. However, these laser welding devices typically have poor flexibility, only capable of welding planar welds with good openness. They are unsuitable for complex structures or irregular curved surfaces, resulting in poor weld quality. Traditional laser welding, on the other hand, is more adaptable to welding irregular curved components, but it is extremely sensitive to assembly gaps and requires high assembly precision. Larger gaps in some areas lead to lower weld pass rates. Furthermore, traditional laser welding can result in excessive gaps due to foil deformation during the welding process, leading to incomplete fusion. Its poor compatibility with ultra-thin foil welding hinders the widespread adoption of traditional laser welding. Additionally, subsequent repair welding processes are complex, and product sealing is difficult to guarantee.

[0003] To address the many shortcomings of existing technologies, there is an urgent need to develop a laser welding method for ultrathin stainless steel foil. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a laser welding method for ultra-thin stainless steel foil, which solves one of the problems in the prior art, such as poor compatibility between traditional laser welding and ultra-thin foil welding, extreme sensitivity to assembly gaps, complex post-weld repair processes, and poor process promotion.

[0005] This invention provides a laser welding method for ultrathin stainless steel foil, comprising the following steps: Step (1) Pre-soldering cleaning: Clean the surface of the substrate within the welding area before soldering; Step (2) Assembly and Fixing: Assemble and fix the test piece with the irregular curved surface structure to be welded; Step (3) Demonstration: During the process, the red light path coincides with the laser beam path shown during welding; Step (4) Welding: Laser welding is used to weld the ultra-thin stainless steel foil; Step (5) Post-weld cleaning; Step (6) Machining steps.

[0006] Furthermore, the thickness of the ultra-thin stainless steel foil is 0.05mm to 0.1mm.

[0007] Further, in step (1) pre-welding cleaning: use a wire brush to clean the surface oxide layer within a 20mm~50mm range of the substrate welding area, so as to expose the bright white metal body. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0008] Further, in step (2) assembly and fixing: during assembly, the ultra-thin stainless steel foil is first attached to the inner surface of the irregular curved surface component, and then the conformal tooling pressure plate is assembled to ensure that the ultra-thin stainless steel foil is attached to the irregular curved surface component and the relative position is fixed, with a gap of no more than 0.02mm.

[0009] Further, in step (3) welding: the ultra-thin stainless steel foil is welded using two laser welding processes.

[0010] Furthermore, the parameters for the first welding pass are: laser power 650-900W, laser oscillation mode "8" shape, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and front argon gas flow rate 15~20L / min.

[0011] Furthermore, after the first weld is completed, adjust the position of the conformal tooling pressure plate so that the edge of the conformal tooling pressure plate is about 0.8-1.2mm away from the edge of the first weld. Then, repeat the teaching process to complete the second weld.

[0012] Furthermore, the parameters for the second welding are: laser power 650-900W, laser oscillation mode "8" shape, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and front argon flow rate 15-20L / min.

[0013] Further, step (6) machining: the burned part of the first weld edge is removed by machining.

[0014] Furthermore, it can also achieve laser welding of 0.1mm~0.3mm stainless steel foil to irregularly shaped curved components.

[0015] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The present invention discloses a laser welding method for ultra-thin stainless steel foil, comprising six steps: pre-weld cleaning, assembly and fixing, teaching (overlapping the red light and laser beam paths), welding, post-weld cleaning, and machining. These steps work synergistically: pre-weld cleaning ensures the cleanliness of the foil and substrate surfaces, preventing welding defects such as porosity and cracks; assembly and fixing ensures the gap between the foil and substrate meets welding requirements; teaching ensures correct welding position; and post-weld cleaning and machining ensure the quality of the weld appearance. Together, these steps guarantee high-quality welding of 0.05-0.1mm ultra-thin stainless steel foil to irregularly shaped curved components, resulting in a smooth weld surface free of oxidation and incomplete welding defects, with excellent sealing performance.

[0016] 2. Existing technologies for welding 0.05-0.1mm ultrathin foils can only achieve planar welding using ultrafast lasers, and cannot achieve welding on complex spatial curved surfaces. This invention leverages the flexibility of traditional lasers by employing a double-pass welding process (the first pass fixes the foil, the second passes seals) to solve the problem of stable connection of 0.05-0.1mm foils using traditional lasers. This enables effective connection of ultrathin foils on complex spatial curved surface structures using traditional lasers, while maintaining excellent sealing performance. The ultrathin stainless steel foil of this invention has a thickness of 0.05mm-0.1mm, clearly defining the core applicable thickness range. At this thickness, the material has extremely low heat capacity and is highly sensitive to heat input; traditional processes are prone to burn-through or failure to fuse. Within this scope, the present invention achieves stable welding through subsequent process design (oscillating laser, two-pass welding, mechanical post-processing, etc.), realizing high-quality and high-sealing welding of 0.05-0.1mm ultrathin foil materials to planar and irregular curved surface structural parts. The weld surface is smooth, free of oxidation and incomplete welding defects, effectively solving the problem of poor compatibility between traditional laser welding and ultrathin foil welding.

[0017] 3. The pre-welding cleaning step of this invention removes oxide scale and oil stains from the joint surface, improving the internal quality of the weld. Mechanical grinding with a wire brush can remove the oxide layer within a range of 20-50mm until the "bright white metal body is exposed." This not only provides an active metal surface for welding, ensuring the metallurgical bonding quality of the weld, but also provides a stable and consistent foundation for subsequent laser energy absorption. The white silk cloth has fine fibers that do not shed lint, and anhydrous ethanol is a powerful organic solvent that evaporates completely without residue. This combination can efficiently remove grease and dust, ensuring chemical cleanliness of the welding area and eliminating the risk of porosity and weld embrittlement caused by contamination from the source.

[0018] 4. Traditional laser welding is extremely sensitive to assembly gaps (usually requiring ≤0.01mm). This invention assembles and fixes the workpiece by pressing a conformal tooling plate with pressure blocks and screws. The conformal tooling plate further presses and fixes the curved structure to the foil. By continuously adjusting the tightness of the pressure blocks, the assembly gap is allowed to not exceed 0.02mm. Furthermore, the welding process combines oscillating laser with argon gas protection. Using the welding method of this invention, the first welding pass is mainly used to fix the foil. After offsetting by a certain distance, the second welding pass is performed to ensure welding quality and effectively compensate for the incomplete welding problem caused by assembly gaps. During the welding process, the foil will deform due to heat. The pressure plate cannot completely fix the foil to the substrate, and there will still be some relative sliding between the foil and the substrate. This sliding will cause the gap during welding to increase from the original 0.01mm to 0.02mm or even larger. Taking 0.05mm foil as an example, when the gap is greater than 0.03mm, an effective connection cannot be formed. In this invention, the first weld seam secures the foil to the substrate. During the second weld, relative sliding between the foil and the substrate on one side is prevented, thus suppressing and reducing the deformation of the foil during welding, thereby improving weld quality. This invention reduces assembly precision requirements and improves weld pass rate and sealing performance. While ensuring weld sealing, this method avoids the extreme sensitivity to assembly gaps inherent in traditional laser welding, reduces reliance on the precision of conformal tooling pressure plates and the technical skills of operators, and improves the overall weld pass rate.

[0019] 5. Existing two-pass welding typically involves overlapping welds along the original path or with a large gap between the two welds, making them two independent welds. These are usually used to improve overall connection strength, and both welds play a decisive role in the final strength. In this invention, the two welds influence each other, with only the second weld ensuring performance. The first weld primarily fixes the foil to the substrate, and the conformal tooling pressure plate ensures that the foil does not deform excessively during the second weld, preventing an increase in the gap between the foil and the substrate. Ultimately, this achieves a good weld between the foil and the substrate, ensuring the product's density. In this invention's welding method, the first weld is mainly used to fix the foil, and the second weld is performed after offsetting it by a certain distance to ensure weld quality. The first weld of this invention has already fixed the foil to the substrate, preventing significant deformation during the second weld, achieving good weld quality and good airtightness. In existing single-pass welding techniques, the weld edge is prone to microscopic burn-off and incomplete fusion due to abrupt changes in heat dissipation conditions, becoming a leak initiation point. Repair welding is complex and prone to burn-through. By moving the conformal fixture of the pressure plate to a distance of 0.8-1.2 mm from the weld edge of the first pass, the second pass can accomplish two key tasks: first, it utilizes the heat-affected zone to thermally repair any microscopic edge defects (such as slight incomplete fusion) that may exist in the first weld; second, it covers and improves the appearance of any slight burn-off or imperfections that may occur on the side of the first weld near the pressure plate due to abrupt changes in heat dissipation conditions. This is equivalent to proactively managing appearance quality and ensuring overall weld quality.

[0020] 6. This invention controls the first and second welding parameters: laser power 650-900W, figure-eight oscillation, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and argon flow rate 15-20L / min. The figure-eight oscillation reconstructs the point heat source into a surface heat source, uniformly distributing heat and stirring the molten pool to prevent burn-through. Argon protection, matched with the parameters, forms a stable gas shield to prevent high-temperature oxidation, ensuring a bright weld without inclusions, thus achieving precise heat input control to "avoid burn-through" and "ensure fusion." With identical welding parameters for both passes, and under the same laser power, oscillation mode, and speed, the width of the heat-affected zone, temperature gradient, and peak temperature generated by the two welds are highly consistent. Microscopic defects at the edge of the first weld are generated under specific heat input and heat dissipation conditions; the second weld uses the exact same welding heat conditions to reheat the defect area. This ensures that the melting and repair of defective areas are controllable and predictable, preventing repair failure due to insufficient heat or excessive remelting due to excessive heat.

[0021] 7. After the first weld is completed, the edge of the conformal pressure plate fixture is adjusted to be 0.8-1.2mm away from the edge of the first weld to complete the second weld. The precise setting of the staggered welding distance (0.8-1.2mm) ensures that the heat-affected zone of the second weld exactly covers the edge of the first weld, achieving "in-situ repair". The staggered distribution of the two welds avoids the superposition of defects, forms a sealing barrier, and ensures the product's sealing performance.

[0022] 8. This invention removes the burned area at the edge of the first weld seam through mechanical processing. It actively removes the microscopically unstable region (burnt, oxidized, incomplete fusion) caused by abrupt changes in heat dissipation in the first weld seam, completely eliminating potential leakage points. This ensures both appearance quality and avoids complex repair welding processes, reducing subsequent processing costs.

[0023] 9. The present invention has strong process compatibility and is applicable to the welding of planar and irregularly shaped curved surface structures using foils of various thicknesses. The method described in this invention is not only applicable to ultra-thin stainless steel foils of 0.05–0.1 mm thickness, but the process parameter range can also be extended to welding foils of 0.1–0.3 mm, demonstrating good process versatility and scalability, possessing strong industrial application potential, and broadening the application scenarios of ultra-thin stainless steel foils in aerospace and other fields.

[0024] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1 is a schematic diagram of the assembly and welding of ultra-thin stainless steel foil; Figure 2 For the welding process of ultra-thin stainless steel foil; Figure 3 A schematic diagram (cross-section) of welding an irregularly shaped curved component to an ultra-thin stainless steel foil.

[0027] Figure label: 1 is the substrate, 2 is the ultra-thin stainless steel foil, 3 is the conformal tooling pressure plate, 4 is the laser beam; 5 is the first welding seam, 6 is the second welding seam, 7 is the weld seam after machining; 8 is the irregular curved surface component, 9 is the ultra-thin stainless steel foil, 10 is the conformal tooling pressure plate, 11 is the laser welding head, 12 is the laser beam, and 13 is the protective gas nozzle. Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0029] With the rapid development of my country's aerospace industry, components are increasingly trending towards lightweight and complex designs, leading to the widespread application of ultra-thin structural units, many of which have complex cross-sections. Currently, ultra-thin structures are mostly welded using ultrafast lasers. However, these laser welding devices typically have poor flexibility and can only weld planar welds with good openness. They are unsuitable for complex structures or irregular curved surfaces, resulting in poor weld quality. Traditional laser welding is well-suited for welding irregular curved components, but it is extremely sensitive to assembly gaps and requires high assembly precision. Large assembly gaps in some areas lead to low weld pass rates. During welding, foil deformation can cause excessive gaps and incomplete fusion, limiting its compatibility with welding ultra-thin foil curved surfaces and hindering the widespread adoption of traditional laser welding. Furthermore, subsequent repair welding processes are complex, product sealing is difficult to guarantee, and overall welding costs are high.

[0030] Therefore, the present invention provides a laser welding method for ultrathin stainless steel foil, comprising the following steps: Step (1) Pre-soldering cleaning: Clean the surface of the substrate within the welding area before soldering; Step (2) Assembly and Fixing: Assemble and fix the test piece to be welded; Step (3) Demonstration: During the process, the red light path coincides with the laser beam path shown during welding; Step (4) Welding: Laser welding is used to weld the ultra-thin stainless steel foil; Step (5) Post-weld cleaning; Step (6) Machining steps.

[0031] Furthermore, the thickness of the ultra-thin stainless steel foil is 0.05mm to 0.1mm.

[0032] Further, in step (1) pre-welding cleaning: use a wire brush to clean the surface oxide layer within a 20mm~50mm range of the substrate welding area, so as to expose the bright white metal body. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the base plate and the ultra-thin stainless steel foil clean.

[0033] The purpose of the pre-welding cleaning step is to remove oxide scale and oil stains from the joint surface, improving the internal quality of the weld. Mechanical grinding with a wire brush can remove the oxide layer within a range of 20-50mm until the "bright white metal body is exposed." This not only provides an active metal surface for welding, ensuring the metallurgical bonding quality of the weld, but also provides a stable and consistent foundation for subsequent laser energy absorption. The fine white silk cloth is lint-free, and anhydrous ethanol is a powerful organic solvent that evaporates completely without residue. This combination effectively removes grease and dust, ensuring chemical cleanliness of the welding area and eliminating the risk of porosity and weld embrittlement caused by contamination at the source.

[0034] Further, in step (2) assembly: the test piece to be welded is assembled and fixed, and the ultra-thin stainless steel foil is pressed tightly to the substrate using a conformal tooling pressure plate, with a gap of no more than 0.02mm.

[0035] During assembly, the substrate is at the bottom, and the ultra-thin stainless steel foil is stacked on top of the substrate. The conformal pressure plate and conformal tooling pressure plate are placed on the stainless steel foil last, and at the same time, downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the ultra-thin stainless steel foil and the substrate do not slide relative to each other during the welding process.

[0036] If the specimen to be welded is an irregularly shaped curved surface component, as shown in the attached... Figure 3 The irregular curved surface component shown is... The difficulty in welding curved structural components to foil lies in the limitations of the welding method. Ultrafast laser equipment is characterized by a gantry structure (two-axis) motion, which can only achieve linear motion in the up, down, left, and right directions. It cannot achieve the rotational motion required for spatial curved trajectories, thus making it impossible to weld spatial curved surfaces. Traditional laser welding equipment uses fiber lasers, which are flexible and equipped with welding robots (six-axis) to achieve linear and rotational motion in the X, Y, and Z directions, thus enabling spatial curved trajectory motion. However, traditional laser welding equipment using general welding methods produces poor welding quality for foil. Therefore, the method of this invention improves the welding quality. When assembling the above-mentioned irregular curved surface components, the ultra-thin stainless steel foil is first attached tightly to the inner surface of the irregular curved surface component. Then, a conformal tooling plate is assembled and pressed tightly using pressure blocks, screws, etc. The conformal tooling plate further presses and fixes the curved structural component and the foil. By continuously adjusting the tightness of the pressure blocks, after assembly, a feeler gauge is used to measure to ensure that the stainless steel foil and the irregular curved surface component are tightly attached, their relative positions are fixed, and the gap is no greater than 0.02mm.

[0037] Ultra-thin stainless steel foil has extremely low heat capacity. If a gap exists between the ultra-thin stainless steel foil and the substrate, a localized "air insulation layer" is formed, interrupting heat conduction and leading to poor fusion. Controlling the assembly gap to no more than 0.02mm ensures large-area metal contact between the ultra-thin stainless steel foil and the substrate. The heat generated by laser irradiation can be rapidly and evenly conducted to the substrate. Under the action of surface tension, the molten ultra-thin stainless steel foil actively fills the tiny gaps, forming a complete metallurgical bond. Traditional laser welding is extremely sensitive to assembly gaps (typically requiring ≤0.01mm) because foil deformation during the process can lead to excessively large gaps and incomplete welding. This invention ensures weld sealing while allowing assembly gaps not exceeding 0.02mm, reducing reliance on the precision of the conformal tooling and the operator's skill, and improving the overall welding pass rate. If the gap is too large, the ultra-thin stainless steel foil may deform under the welding heat, making a second welding impossible.

[0038] Furthermore, the red light path during the teaching process in step (3) coincides with the laser beam path during welding. During the teaching process, the distance between the red light and the edge of the conformal tooling pressure plate is 0.8-1.2 mm, and the laser defocusing amount is adjusted.

[0039] The red light path during the teaching process coincides with the laser beam path during welding. The clear red light trajectory allows for intuitive and safe path planning and verification, lowering the technical barrier and improving the scalability and consistency of the process. Previewing the path with red light avoids batch defects caused by incorrect paths, saving significant material costs and rework time. During the teaching process, the red light distance from the edge of the conformal tooling pressure plate is 0.8-1.2 mm (exemplary distances are 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, and 1.2 mm). Adjusting the laser defocus is crucial; excessive distance will cause the pressure plate tooling to fail to clamp, resulting in poor welding quality; insufficient distance will cause the pressure plate tooling to melt and weld together with the foil during welding, also affecting welding quality.

[0040] Further, in step (4) welding: laser welding is used to perform two welding processes on the ultra-thin stainless steel foil.

[0041] After the first weld is completed, adjust the position of the conformal tooling pressure plate to 0.8-1.2mm from the edge of the first weld before welding the second weld, achieving a staggered weld between the second and first welds. The parameters for the first weld are: laser power 650-900W, laser oscillation mode "8", oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and frontal argon flow rate 15-20L / min. After the first weld is completed, adjust the position of the conformal tooling pressure plate so that its edge is 0.8-1.2mm from the edge of the first weld. Then, re-teach the process, ensuring the red light path during teaching coincides with the laser beam path during welding, with the red light 0.8-1.2mm from the edge of the conformal tooling pressure plate. Finally, adjust the laser defocusing amount to complete the second weld. The parameters for the second welding pass are as follows: laser power 650-900W, laser oscillation mode "8" shape, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and front argon gas flow rate 15-20L / min. The parameters for the second welding pass are the same as those for the first welding pass.

[0042] Laser welding is used to perform two-pass welding on ultra-thin stainless steel foil. The first pass is used to fix the ultra-thin foil to the substrate, preventing significant deformation during the second pass and achieving good weld quality and airtightness. Existing single-pass welding techniques often result in microscopic burns and incomplete fusion at the weld edge due to abrupt changes in heat dissipation, becoming the starting point for leaks; repair welding is complex and prone to burn-through. By moving the conformal tooling pressure plate to a distance of 0.8-1.2 mm from the weld edge of the first pass, the second pass accomplishes two key tasks: first, it uses its heat-affected zone to thermally repair any microscopic edge defects (such as slight incomplete fusion) that may exist in the first weld; second, it covers and improves the appearance of any slight burns or imperfections that may occur on the side of the first weld near the pressure plate due to abrupt changes in heat dissipation. This proactively manages appearance quality and ensures weld quality. With identical welding parameters—laser power, oscillation mode, speed, etc.—the width of the heat-affected zone, temperature gradient, and peak temperature are highly consistent between the two passes. The microscopic defects at the edge of the first weld are generated under specific heat input and dissipation conditions. The second weld uses the exact same welding heat conditions to reheat the defect area. This ensures that the melting and repair of the defect area is controllable and predictable—neither repair failure due to insufficient heat nor over-remelting due to excessive heat.

[0043] During the welding process, the foil will deform to some extent due to heat. The pressure plate cannot completely fix the foil to the substrate, and there will still be some relative sliding between the foil and the substrate. This sliding will cause the gap during the welding process to increase from the original 0.01mm to 0.02mm or even larger. Taking 0.05mm foil as an example, when the gap is greater than 0.03mm, an effective connection cannot be formed. In this invention, the first weld has already fixed the foil to the substrate. During the second weld, there will be no relative sliding between the foil and the substrate on one side. The deformation of the foil during the welding process is suppressed to a certain extent, and the amount of deformation is reduced, thereby improving the welding quality.

[0044] The figure-eight oscillation mode of the laser oscillation mode can effectively stir the molten pool and break up the oxide film.

[0045] The figure-eight oscillation mode of the laser oscillation mode, combined with a laser power of 650-900W, features an oscillation frequency of 60-90Hz, an oscillation amplitude of 0.8-1.2mm, and a welding speed of 1.5-2.5m / min. The figure-eight oscillation reconstructs the point heat source into a surface heat source, uniformly distributing heat and stirring the molten pool, achieving dual precise control of laser energy and the molten pool, "avoiding burn-through" and "ensuring fusion".

[0046] An argon flow rate of 15-20 L / min is precisely matched with the welding speed and laser power. This flow rate forms a stable and sufficient gas shield, effectively isolating air, preventing high-temperature oxidation, preventing the ultra-thin stainless steel foil from oxidizing and turning black, ensuring that the weld has a bright metallic color and no internal oxide inclusions.

[0047] Laser power determines the weld penetration and total heat input, oscillation frequency regulates keyhole stability and molten pool stirring intensity, and oscillation amplitude alters energy distribution and range of action. These three factors work together to reshape keyhole dynamics and molten pool flow field, jointly determining the weld penetration, weld width, porosity, and weld quality.

[0048] Laser power: The core controller of weld depth and width. Increased power increases both weld depth and width; excessive power can lead to burn-through and spatter, while insufficient power results in poor fusion. Oscillating frequency: Determines the number of scans per unit time, affecting keyhole stability and molten pool stirring. Too low a frequency can cause keyhole collapse and porosity, while too high a frequency will widen the keyhole, decrease energy density, and trap bubbles. Oscillating amplitude: Changes the trajectory and range of the laser spot. Increased amplitude increases weld width, decreases energy density, and reduces the depth-to-width ratio; excessive amplitude can cause edge biting and burning.

[0049] Laser power determines the basic melt depth, frequency adjusts keyhole stability and stirring, and amplitude controls energy dispersion. High power with high frequency can stabilize the keyhole, reduce porosity, and improve efficiency; low power with low frequency is prone to keyhole collapse and increased porosity; high power with small amplitude can maintain deep melt and increase melt width; high power with large amplitude is prone to energy dispersion, resulting in insufficient melt depth and poor forming; low frequency with large amplitude results in unstable keyhole and many porosity, while high frequency with large amplitude results in energy asymmetry and edge biting.

[0050] For example, the laser power is 650 W, 700 W, 750 W, 800 W, 850 W, or 900 W; the laser oscillation frequency is 60 Hz, 65 Hz, 70 Hz, 75 Hz, 80 Hz, 85 Hz, or 90 Hz; the oscillation amplitude is 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, or 1.2 mm; and the welding speed is 1.5 m / min, 1.7 m / min, 1.9 m / min, 2.1 m / min, 2.3 m / min, or 2.5 m / min. If the laser power is too high, the oscillation frequency is too high, the oscillation amplitude is too low, the welding speed is too slow, or the argon gas flow rate is too high, it is very easy to cause the ultrathin foil to burn through instantly, forming holes, resulting in poor weld formation, leading to continuous welds, shallow penetration, and incomplete weld penetration. Excessive argon gas flow may blow over or interfere with the stability of the molten pool of the ultrathin foil. If the laser power is too low, the oscillation frequency is too low, the oscillation amplitude is too high, the welding speed is too fast, or the argon flow rate is too low, the root will not be welded, the sealing will fail, the molten pool will not be effectively stirred and the heat will not be dispersed, and porosity and undercut will easily occur. Insufficient argon protection will result in severe oxidation and blackening of the weld surface.

[0051] Further, step (5) post-weld cleaning: after welding, use a wire brush to clean the black ash around the weld.

[0052] After welding, use a wire brush to clean the black ash around the weld. The cleaning effect of the wire brush is concentrated on the loosely attached black ash, without damaging the formed stainless steel substrate and the surface of the high-quality weld, thus avoiding surface scratches that may be caused by excessive cleaning.

[0053] Furthermore, step (6) machining: the burned part of the first weld edge is removed by machining to ensure the overall appearance quality of the product.

[0054] In the first welding pass, the weld edge is tightly pressed against the conformal tooling pressure plate, making it highly susceptible to localized overheating. This can lead to microscopic, irregular burns, oxidation, or slight incomplete fusion at the edge. Although these defects are small, they can become the starting point for leaks in high-requirement sealing structures. Machining this area completely removes the weld, ensuring a smooth transition between the weld area and the substrate, guaranteeing the overall appearance quality of the product and good weld airtightness. The welded product is then securely fixed to the machine tool using a pressure plate or specialized fixture, ensuring rigidity and preventing deformation and vibration. A dial indicator is used to align the reference surface, and the appropriate cutting tool is selected. After tool setting and workpiece coordinate system determination, the appropriate machining program is chosen. A small trial cut with minimal allowance is performed, and after confirming no problems, formal machining proceeds to remove the burnt portions of the weld edge, ensuring the overall appearance quality of the product.

[0055] In summary, the laser welding scheme for ultra-thin stainless steel foil designed in this invention mainly includes pre-weld cleaning, assembly, teaching, welding, post-weld cleaning, and machining. It can achieve laser welding of 0.05mm~0.1mm ultra-thin stainless steel foil to planar and irregularly curved structural parts, producing welds with excellent sealing properties. Furthermore, the weld surface is smooth, with a rounded transition, and free from oxidation and incomplete welding defects. This invention solves the problems of poor compatibility between traditional laser welding and ultra-thin foil curved surface welding, extreme sensitivity to assembly gaps, complex post-weld repair processes, and poor process promotion in existing technologies, thus improving welding quality. The process of this invention has strong compatibility and is applicable to welding various ultra-thin foils. The method described in this invention is not only applicable to 0.05–0.1mm thick stainless steel foil, but the process parameter range can also be extended to welding foils of 0.1–0.3mm, demonstrating good process versatility and scalability, and possessing strong industrial application potential.

[0056] The following specific embodiments further illustrate a laser welding method for ultrathin stainless steel foil according to the present invention.

[0057] Example 1 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3 As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.05mm and a substrate thickness of 3mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 20mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0058] (2) Assembly: Use conformal tooling pressure plates to press the stainless steel foil to the irregular curved surface component, with a gap of no more than 0.02mm. During assembly, first press the stainless steel foil tightly against the inner surface of the irregular curved surface component, and then assemble the conformal tooling pressure plates. Press the conformal tooling pressure plates with pressure blocks, screws, etc., and then the conformal tooling pressure plates further press and fix the curved surface component and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, use a feeler gauge to measure to ensure that the stainless steel foil and the irregular curved surface component are tightly attached and their relative positions are fixed, and the gap is no more than 0.02mm.

[0059] (3) Teaching: The welding path is taught through the teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the red light distance is 1mm from the edge of the conformal tooling pressure plate. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0060] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 60Hz, oscillation amplitude 1.0mm, welding speed 1.5m / min, and front argon flow rate 15L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.8mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.8mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The parameters for the second pass were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 60Hz, oscillation amplitude 1.0mm, welding speed 1.5m / min, and front argon flow rate 15L / min.

[0061] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0062] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0063] Example 2 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.1mm and a substrate thickness of 4mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Pre-welding cleaning: Use a wire brush to remove the oxide layer on the surface of the irregular curved component within 40mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the irregular curved component and stainless steel foil clean.

[0064] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the stainless steel foil and the irregular curved surface component together, with a gap of no more than 0.02 mm. During assembly, first press the stainless steel foil against the inner surface of the irregular curved surface component, and then assemble the conformal tooling plate. Press the conformal tooling plate with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved surface component and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, use a feeler gauge to measure to ensure that the stainless steel foil and the irregular curved surface component are close together and the relative position is fixed, and the gap is no more than 0.02 mm.

[0065] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the red light distance from the edge of the conformal tooling pressure plate is 0.09 mm. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0066] (4) Welding: Laser welding was used to weld the stainless steel foil to the irregular curved surface component in the first round. The welding parameters were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 0.8mm, welding speed 1.6m / min, and front argon flow rate 15L / min. After the first weld was completed, the position of the conformal tooling pressure plate was adjusted so that the edge of the conformal tooling pressure plate was 1mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1mm away from the edge of the conformal tooling pressure plate. Then, the laser defocusing was adjusted to complete the second weld. The parameters for the second weld were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 0.8mm, welding speed 1.6m / min, and front argon flow rate 15L / min.

[0067] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0068] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0069] Example 3 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3 As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.08mm and a substrate thickness of 4mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 30mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0070] (2) Assembly: The test piece to be welded is assembled and fixed. The ultra-thin stainless steel foil is pressed tightly to the substrate using a conformal pressure plate and conformal tooling pressure plate, with a gap of no more than 0.02 mm. During assembly, the stainless steel foil is first pressed tightly against the inner surface of the irregular curved component, and then the conformal tooling pressure plate is assembled. The conformal tooling pressure plate is pressed tightly by pressure blocks, screws, etc. Then the conformal tooling pressure plate further presses and fixes the curved structure and foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are pressed tightly together and their relative positions are fixed, and the gap is no more than 0.02 mm, as measured by a feeler gauge.

[0071] (3) Teaching: The welding path is taught through the teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the red light distance is 1mm from the edge of the conformal tooling pressure plate. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0072] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 1.2mm away from the edge of the first weld. Then, the teaching process was repeated. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1.2mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The parameters for the second pass were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min.

[0073] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0074] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0075] Example 4 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3 As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.2mm and a substrate thickness of 4.5mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Pre-welding cleaning: Use a wire brush to remove the oxide layer on the surface of the irregular curved component within 50mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the irregular curved component and stainless steel foil clean.

[0076] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the stainless steel foil and the irregular curved surface component together, with a gap of no more than 0.02 mm. During assembly, first press the stainless steel foil against the inner surface of the irregular curved surface component, and then assemble the conformal tooling plate. Press the conformal tooling plate with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved surface component and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, use a feeler gauge to measure to ensure that the stainless steel foil and the irregular curved surface component are close together and the relative position is fixed, and the gap is no more than 0.02 mm.

[0077] (3) Teaching: The welding path is taught through the teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the distance between the red light and the edge of the conformal tooling pressure plate is 0.8mm. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0078] (4) Welding: Laser welding was used to weld the stainless steel foil to the irregular curved surface component in the first round. The welding parameters were: laser power 680W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 0.9mm, welding speed 2.0m / min, and front argon flow rate 19L / min. After the first weld was completed, the position of the conformal tooling pressure plate was adjusted so that the edge of the conformal tooling pressure plate was 1.1mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1.1mm away from the edge of the conformal tooling pressure plate. Then, the laser defocusing was adjusted to complete the second weld. The parameters for the second weld were: laser power 680W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 0.9mm, welding speed 2.0m / min, and front argon flow rate 19L / min.

[0079] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0080] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0081] Example 5 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.3mm and a substrate thickness of 5mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Pre-welding cleaning: Use a wire brush to remove the oxide layer on the surface of the irregular curved component within 20mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the irregular curved component and stainless steel foil clean.

[0082] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the stainless steel foil and the irregular curved surface component together, with a gap of no more than 0.02 mm. During assembly, first press the stainless steel foil against the inner surface of the irregular curved surface component, and then assemble the conformal tooling plate. Press the conformal tooling plate with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved surface component and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, use a feeler gauge to measure to ensure that the stainless steel foil and the irregular curved surface component are close together and the relative position is fixed, and the gap is no more than 0.02 mm.

[0083] (3) Teaching: The welding path is taught through the teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the distance between the red light and the edge of the conformal tooling pressure plate is 0.8mm. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0084] (4) Welding: Laser welding was used to weld the stainless steel foil to the irregular curved surface component in the first round. The welding parameters were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min. After the first weld was completed, the position of the conformal tooling pressure plate was adjusted so that the edge of the conformal tooling pressure plate was 1.2mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1.2mm away from the edge of the conformal tooling pressure plate. Then, the laser defocusing was adjusted to complete the second weld. The parameters for the second weld were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min.

[0085] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0086] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0087] Example 6 This embodiment provides a method for laser welding irregularly shaped curved surface components to stainless steel foil, including the following steps: like Figure 3 As shown in the diagram, this is a cross-sectional view. The actual welding process involves inserting the laser welding head into the structural component for welding. The joint structure is a lap joint, with a stainless steel foil thickness of 0.25mm and a substrate thickness of 5mm. The two are assembled using a conformal tooling clamp, and then laser welding is performed. The specific steps are as follows: (1) Pre-welding cleaning: Use a wire brush to remove the oxide layer on the surface of the irregular curved component within 40mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the irregular curved component and stainless steel foil clean.

[0088] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the stainless steel foil and the irregular curved surface component together, with a gap of no more than 0.02 mm. During assembly, first press the stainless steel foil against the inner surface of the irregular curved surface component, and then assemble the conformal tooling plate. Press the conformal tooling plate with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved surface component and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, use a feeler gauge to measure to ensure that the stainless steel foil and the irregular curved surface component are close together and the relative position is fixed, and the gap is no more than 0.02 mm.

[0089] (3) Teaching: The welding path is taught through the teaching pendant. The red light path during the teaching process coincides with the laser beam path during the welding process. During the teaching process, the red light distance is 1mm from the edge of the conformal tooling pressure plate. The laser defocusing amount is adjusted, and the teaching is carried out in the order of "circular arc - oblique straight line segment - flat straight line segment - oblique straight line segment".

[0090] (4) Welding: Laser welding was used to weld the stainless steel foil to the irregular curved surface component in the first round. The welding parameters were: laser power 800W, laser oscillation mode "8" shape, oscillation frequency 80Hz, oscillation amplitude 0.9mm, welding speed 2.1m / min, and front argon flow rate 17L / min. After the first weld was completed, the position of the conformal tooling pressure plate was adjusted so that the edge of the conformal tooling pressure plate was 1.1mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1.1mm away from the edge of the conformal tooling pressure plate. Then, the laser defocusing was adjusted to complete the second weld. The parameters for the second weld were: laser power 800W, laser oscillation mode "8" shape, oscillation frequency 80Hz, oscillation amplitude 0.9mm, welding speed 2.1m / min, and front argon flow rate 17L / min.

[0091] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0092] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0093] Example 7 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1 As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.05mm, and the substrate thickness is 5mm. The two are assembled using a conformal clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 50mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0094] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling plate is placed on the stainless steel foil last, and downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling plate is pressed with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other, their relative positions are fixed, and the gap is no more than 0.02 mm.

[0095] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light is 1.2mm away from the edge of the pressure plate or conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0096] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 60Hz, oscillation amplitude 1.0mm, welding speed 1.5m / min, and front argon flow rate 15L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.8mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.8mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The parameters for the second pass were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 60Hz, oscillation amplitude 1.0mm, welding speed 1.5m / min, and front argon flow rate 15L / min.

[0097] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0098] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0099] Example 8 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.08mm, and the substrate thickness is 4mm. The two are assembled using a conformal clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 40mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0100] (2) Assembly: Assemble and fix the test piece to be welded. Use a pressure plate or conformal tooling pressure plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling pressure plate is placed on the stainless steel foil last, and downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling pressure plate is pressed with pressure blocks, screws, etc., and then the conformal tooling pressure plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other and the relative position is fixed with a gap of no more than 0.02 mm.

[0101] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light distance is 1mm from the edge of the conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0102] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 1.0mm, welding speed 1.8m / min, and front argon flow rate 18L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.9mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.9mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The parameters for the second pass were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 1.0mm, welding speed 1.8m / min, and front argon flow rate 18L / min.

[0103] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0104] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0105] Example 9 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1 As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.1mm, and the substrate thickness is 4mm. The two are assembled using a conformal tooling clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 40mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0106] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling plate is placed on the stainless steel foil last, and downward pressure is applied to the stainless steel foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling plate is pressed with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other and the relative position is fixed with a gap of no more than 0.02 mm.

[0107] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light is 0.9 mm away from the edge of the pressure plate or conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0108] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min. After the first pass was completed, the position of the pressure plate or conformal tooling pressure plate was adjusted so that the edge of the conformal tooling pressure plate was 1.1mm away from the edge of the first weld. Then, the teaching process was repeated. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 1.1mm away from the edge of the conformal tooling pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The parameters for the second pass were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min.

[0109] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0110] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0111] Example 10 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1 As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.2mm, and the substrate thickness is 5mm. The two are assembled using a conformal tooling clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 50mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0112] (2) Assembly: Assemble and fix the test piece to be welded. Use a conformal tooling plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling plate is placed on the stainless steel foil last, and downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling plate is pressed with pressure blocks, screws, etc., and then the conformal tooling plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other, their relative positions are fixed, and the gap is no more than 0.02 mm.

[0113] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light is 1.1 mm away from the edge of the pressure plate or conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0114] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 65Hz, oscillation amplitude 0.9mm, welding speed 1.5m / min, and front argon flow rate 15L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.8mm away from the edge of the first weld. Then, the teaching process was repeated. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.8mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The welding parameters were: laser power 650W, laser oscillation mode "8" shape, oscillation frequency 65Hz, oscillation amplitude 0.9mm, welding speed 1.5m / min, and front argon flow rate 15L / min.

[0115] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0116] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0117] Example 11 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.3mm, and the substrate thickness is 5mm. The two are assembled using a conformal tooling clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 50mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0118] (2) Assembly: Assemble and fix the test piece to be welded. Use a pressure plate or conformal tooling pressure plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling pressure plate is placed on the stainless steel foil last, and downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling pressure plate is pressed with pressure blocks, screws, etc., and then the conformal tooling pressure plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other and the relative position is fixed with a gap of no more than 0.02 mm.

[0119] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light is 1.2mm away from the edge of the pressure plate or conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0120] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.8mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.8mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The welding parameters were: laser power 900W, laser oscillation mode "8" shape, oscillation frequency 90Hz, oscillation amplitude 1.2mm, welding speed 2.5m / min, and front argon flow rate 20L / min.

[0121] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0122] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0123] Example 12 This embodiment provides a laser welding method for ultrathin stainless steel foil, including the following steps: like Figure 1 As shown, the joint structure is a lap joint, the stainless steel foil thickness is 0.25mm, and the substrate thickness is 5mm. The two are assembled using a conformal tooling clamping plate, and then laser welding is performed. The specific steps are as follows: (1) Cleaning before welding: Use a wire brush to remove the oxide layer on the surface of the substrate within 40mm of the welding area, so that the bright white metal body is exposed. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

[0124] (2) Assembly: Assemble and fix the test piece to be welded. Use a pressure plate or conformal tooling pressure plate to press the ultra-thin stainless steel foil to the substrate, with a gap of no more than 0.02 mm. During assembly, the substrate is at the bottom, and the stainless steel foil is stacked on top of the substrate. The conformal tooling pressure plate is placed on the stainless steel foil last, and downward pressure is applied to the foil to ensure that the assembly gap meets the requirements and that the stainless steel foil and the substrate do not slide relative to each other during the welding process. The conformal tooling pressure plate is pressed with pressure blocks, screws, etc., and then the conformal tooling pressure plate further presses and fixes the curved structure and the foil. By continuously adjusting the tightness of the pressure blocks, after the assembly is completed, the stainless steel foil and the irregular curved component are measured with a feeler gauge to ensure that they are close to each other and the relative position is fixed with a gap of no more than 0.02 mm.

[0125] (3) Teaching: The welding path is taught using a teaching pendant. The red light path during the teaching process coincides with the laser beam path during welding. During the teaching process, the red light is 0.9 mm away from the edge of the pressure plate or conformal tooling pressure plate, and the laser defocusing amount is adjusted.

[0126] (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 1.0mm, welding speed 1.7m / min, and front argon flow rate 18L / min. After the first pass was completed, the position of the conformal fixture pressure plate was adjusted so that the edge of the conformal fixture pressure plate was 0.9mm away from the edge of the first weld. Then, the teaching was performed again. The red light path during the teaching process coincided with the laser beam path during the welding process. The red light was 0.9mm away from the edge of the conformal fixture pressure plate. Then, the laser defocusing was adjusted to complete the second pass. The welding parameters were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 1.0mm, welding speed 1.7m / min, and front argon flow rate 18L / min.

[0127] (5) Post-weld cleaning: After welding, use a wire brush to clean the black ash around the weld.

[0128] (6) Machining: Remove the burned parts of the first weld edge by machining. Use pressure plates or special fixtures to fix the welded product on the machine tool. Ensure the clamping is firm and rigid to prevent deformation and vibration. Use a dial indicator to align the reference surface, select the appropriate tool, set the tool to determine the workpiece coordinate system, select the appropriate machining program, and perform a small-scale trial cut. After ensuring there are no problems, proceed with the formal machining to remove the burned parts of the weld edge and ensure the overall appearance quality of the product.

[0129] Comparative Example 1 (2) Assembly: The test piece to be welded is assembled and fixed. The ultra-thin stainless steel foil is pressed tightly to the substrate using a conformal tooling plate with a gap of 0.03 mm. The rest is the same as in Example 1.

[0130] Comparative Example 2 (4) Welding: The stainless steel foil was first welded using laser welding. The welding parameters were as follows: laser power 1000W, laser oscillation mode "8" shape, oscillation frequency 200Hz, oscillation amplitude 1.5mm, welding speed 1.8m / min, and front argon gas flow rate 25L / min. The rest were the same as in Example 1.

[0131] Comparative Example 3 (4) Welding: The stainless steel foil was welded using laser welding for the first pass. The welding parameters were: laser power 700W, laser oscillation mode "8" shape, oscillation frequency 70Hz, oscillation amplitude 1.0mm, welding speed 1.8m / min, and front argon gas flow rate 18L / min. After the first pass was completed, no second pass was welded. The rest was the same as in Example 8.

[0132] Comparative Example 4 (4) Welding: After the first weld is completed, adjust the position of the conformal tooling pressure plate so that the edge of the conformal tooling pressure plate is 3mm away from the edge of the first weld. Then, repeat the teaching process to complete the welding of the second weld. The rest is the same as in Example 1.

[0133] Performance testing The airtightness of Examples 1-12 and Comparative Examples 1-4 described above was tested, and the results are shown in Table 1. The tests were performed in accordance with GB / T 150.4-2011, and the results are shown in Table 1.

[0134] Table 1. Results of airtightness test

[0135] As can be seen from Table 1, the welding of ultra-thin stainless steel foil in Examples 1-12 using the parameters and methods within the scope of protection of this invention resulted in welds with good sealing performance. Furthermore, the weld surfaces of Examples 1-12 were smooth, with rounded transitions, and free from oxidation and incomplete welding defects. In contrast, the welds of Comparative Examples 1-4, which were not within the scope of protection of this invention, exhibited poor sealing performance under the welding parameters and methods used, failing to meet practical application requirements.

[0136] In some embodiments, the pressure value at the end of the test is greater than the pressure value at the beginning of the test. This is because in general testing, an increase in ambient temperature may also cause an increase in the pressure of the sealed container, and the change value (0.5%) is within the allowable error range.

[0137] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser welding method for ultrathin stainless steel foil, characterized in that, Includes the following steps: Step (1) Pre-soldering cleaning: Clean the surface of the substrate within the welding area before soldering; Step (2) Assembly and Fixing: Assemble and fix the test piece to be welded; Step (3) Demonstration: During the process, the red light path coincides with the laser beam path shown during welding; Step (4) Welding: Laser welding is used to weld the ultra-thin stainless steel foil; Step (5) Post-weld cleaning; Step (6) Machining steps.

2. The method according to claim 1, characterized in that, The thickness of the ultra-thin stainless steel foil is 0.05mm to 0.1mm.

3. The method according to claim 1, characterized in that, Step (1) Pre-welding cleaning: Use a wire brush to clean the oxide layer on the surface of the substrate within a range of 20mm to 50mm in the welding area, so as to expose the bright white metal body. Then use a white silk cloth dipped in anhydrous ethanol to wipe the surface of the substrate and the ultra-thin stainless steel foil clean.

4. The method according to claim 1, characterized in that, Step (2) Assembly and fixing: During assembly, first attach the ultra-thin stainless steel foil to the inner surface of the irregular curved surface component, and then assemble the conformal tooling pressure plate to ensure that the ultra-thin stainless steel foil is attached to the irregular curved surface component and the relative position is fixed, with a gap of no more than 0.02mm.

5. The method according to claim 1, characterized in that, Step (4) Welding: The ultra-thin stainless steel foil is welded using two laser welding processes.

6. The method according to claim 5, characterized in that, The parameters for the first welding pass are: laser power 650-900W, laser oscillation mode "8" shape, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and front argon flow rate 15~20L / min.

7. The method according to claim 6, characterized in that, After the first weld is completed, adjust the position of the conformal tooling pressure plate so that the edge of the conformal tooling pressure plate is about 0.8-1.2mm away from the edge of the first weld. Then, repeat the teaching process to complete the second weld.

8. The method according to claim 8, characterized in that, The parameters for the second welding pass are: laser power 650-900W, laser oscillation mode "8" shape, oscillation frequency 60-90Hz, oscillation amplitude 0.8-1.2mm, welding speed 1.5-2.5m / min, and front argon flow rate 15-20L / min.

9. The method according to claim 1, characterized in that, Step (6) Machining: Remove the burned parts at the edge of the first weld by machining.

10. The method according to claim 1, characterized in that, It can also achieve laser welding of 0.1mm~0.3mm stainless steel foil to irregular curved surface components.

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