Brazing method for closed impeller with curvature narrow flow channel

Abstract

The present invention discloses a brazing method for a closed impeller with a curvature and narrow flow channel, comprising the following steps: S1. Extracting the surface profile of the blade to be welded at the connection between the blade and the shroud based on a three-dimensional model to generate a brazing filler metal cutting template; S2. Cutting and segmenting the brazing filler metal foil according to the brazing filler metal cutting template; S3. Laying the cut brazing filler metal foil to the surface of the blade to be welded, and spot welding the brazing filler metal and the blade; S4. Test-assembling and adjusting the relative position of the blade and the shroud to ensure a uniform assembly gap; S5. Fixing the blade and the shroud using a fixture; and S6. Vacuum brazing. This method can accurately and evenly fill the closed impeller with a curvature and narrow flow channel with brazing filler metal, ensuring the quality of the final joint.

Description

Technical Field

[0001] The invention relates to the technical field of brazing, in particular to a brazing method for a closed impeller with a curvature narrow flow channel. Background Art

[0002] Small, curved, closed impellers are widely used in aviation, energy, and industrial compressors. Due to their complex geometry, these impellers are typically manufactured by machining separate parts and then joining them together.

[0003] Conventional fusion welding methods (such as arc welding or laser welding) are often limited in processing the connection between blades and shrouds due to the following problems:

[0004] 1. The narrow flow channel and the twisted shape of the blade prevent the welding gun from penetrating deeply.

[0005] 2. Fusion welding can easily cause deformation of the joint area, affecting the balance performance of the impeller.

[0006] Vacuum brazing is the preferred process due to its advantages of uniform heating, minimal deformation, and ability to complete multiple welds simultaneously. However, the key to this process lies in the pre-welding filler metal. Especially for structures with curvature, how to accurately and evenly fill the filler metal is a key issue affecting the quality of the final joint. Summary of the Invention

[0007] The object of the present invention is to provide a brazing method for a closed impeller with a narrow curvature flow channel in order to solve the above-mentioned problems, so as to accurately and evenly fill the closed impeller with a narrow curvature flow channel with brazing material to ensure the quality of the final joint.

[0008] The technical solution adopted in the present invention is as follows:

[0009] A brazing method for a closed impeller with a curvature narrow flow channel comprises the following steps:

[0010] S1. Extract the surface profile of the connection between the blade and the wheel cover to be welded based on the 3D model and generate a solder cutting template;

[0011] S2, cutting the solder foil strip into sections according to the solder cutting template;

[0012] S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade;

[0013] S4. Test-assemble and adjust the relative position of the blades and wheel cover to ensure uniform assembly clearance;

[0014] S5. Use fixtures to fix the blades and wheel covers;

[0015] S6. Perform vacuum brazing.

[0016] Optionally, S1 includes the following steps:

[0017] S11. Create a three-dimensional model of the impeller using three-dimensional modeling software;

[0018] S12. Select the surface to be welded at the connection between the blade and the wheel cover in the model, extract its profile, and project it onto a plane;

[0019] S13, increasing the volume along the profile line toward the periphery to generate a solder cutting template.

[0020] Alternatively, in S12, projection is performed perpendicular to the line connecting the vertex and the bottom point of the wheel cover surface.

[0021] Alternatively, in S12, the length of the profile can be extended by 5-10 mm towards both ends.

[0022] Alternatively, in S13, a 1 to 3 mm increase in size is made along the profile toward the periphery to generate a solder cutting template.

[0023] Alternatively, in S2, a foil solder with a thickness of 0.03 to 0.05 mm is selected and cut according to the cutting template.

[0024] Alternatively, in S2, the foil solder is segmented in 3D modeling software according to torsion changes; or, the cut foil solder is first tried to fit the blade surface, and the segmentation position is determined based on the actual fit of the solder on the blade surface.

[0025] Alternatively, in S3, the cut foil solder is applied to the surface of the blade to be welded section by section, ensuring that the solder edge is consistent with the margin reserved for the profile.

[0026] Alternatively, in S3, low-current resistance spot welding is used to fix the solder, and each section of solder is spot welded in sequence along its outer contour, with the spot welding spacing controlled at 10 to 15 mm.

[0027] Alternatively, in S6, the assembled blades, wheel covers and fixtures are placed in a vacuum furnace and heated according to the set brazing parameters. The temperature range is 1000~1100℃ and the vacuum degree is less than 10 -2 Pa.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] The present invention provides a brazing method for a closed impeller with a narrow curvature flow channel. Through precise brazing material pre-setting and vacuum brazing technology, it solves many problems of traditional fusion welding methods in processing closed impellers with narrow curvature flow channels. It has significant advantages such as high welding quality, small deformation, adaptability to complex structures, high efficiency and good cost-effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0031] Figure 1 It is a schematic diagram of the process of this brazing method.

[0032] Figure 2 It is a schematic diagram of the solder cutting template. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below with reference to the accompanying drawings.

[0034] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0035] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0036] A brazing method for a closed impeller with a narrow curvature flow channel, such as Figure 1 As shown, the following steps are included:

[0037] S1. Extract the surface profile of the blade and wheel cover to be welded based on the 3D model and generate a solder cutting template, such as Figure 2 As shown;

[0038] S2, cutting the solder foil strip into sections according to the solder cutting template;

[0039] S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade;

[0040] S4. Test-assemble and adjust the relative position of the blades and wheel cover to ensure uniform assembly clearance;

[0041] S5. Use fixtures to fix the blades and wheel covers;

[0042] S6. Perform vacuum brazing.

[0043] The blades of an impeller usually have complex curvatures and torsional shapes, which are difficult to accurately process using traditional manual measurement and template making methods. However, 3D modeling software can easily handle these complex curved surfaces, ensuring that the cutting template is highly matched with the surface to be welded. This solution uses reverse modeling technology to extract the 3D profile of the blades and generates a solder template through parametric modeling to achieve high-precision matching between the solder shape and the curved surface. Avoid solder accumulation or shortage, thereby improving welding quality. The plastic deformation characteristics of flexible foil solder can adapt to the complex curvature of the blades and are suitable for impeller structures with narrow curvature channels. Prestressed forming technology is used to ensure the fit between the solder and the complex curved surface. Vacuum brazing achieves uniform filling of the solder, ensuring the strength and sealing of the welded joint. It provides a uniform heating environment, reduces deformation, and completes multiple welds simultaneously, improving welding efficiency and joint quality.

[0044] Among them, S1 generates a profile template based on a three-dimensional model to ensure the matching degree of the brazing material and the weld curvature, reduce the need for subsequent processing and repair, and solve the problem of uneven brazing material filling caused by insufficient surface fitting in traditional methods. S2 Foil brazing material has good flexibility and plasticity and can adapt to the complex curvature of the blade. Using a cutting template, you can accurately cut out a brazing foil that fits the curved shape of the blade, and cut the brazing material in sections according to the torsion angle of the blade. Each section of brazing material can better adapt to the local torsion angle of the blade, ensuring that the brazing material on the complex geometric surface is fully fitted. S3 fits the brazing foil to the blade and temporarily fixes the brazing material to the blade by spot welding, ensuring the positional stability of the brazing material during the welding process and avoiding displacement of the brazing material during the welding process. S4 performs trial assembly and adjustment before formal welding to ensure that the assembly gap between the blade and the wheel cover is uniform. A uniform assembly gap helps the brazing material flow evenly during the welding process and avoids welding defects caused by uneven gaps. The S5 fixture provides sufficient rigidity to ensure precise positioning of the blades and shroud during vacuum brazing, preventing relative movement during welding. The S6 vacuum brazing process provides uniform heating, reducing thermal stress and deformation. The brazing filler metal melts and fills the gap between the blades and shroud, achieving complete coverage through capillary action, forming a uniform and dense joint. The vacuum environment reduces oxide formation, improving the strength and reliability of the welded joint. Uniform heating further minimizes weld distortion, ensuring impeller balance.

[0045] As another specific implementation, S1 includes the following steps:

[0046] S11. Use 3D modeling software to create a 3D model of the impeller (including blades and shroud); use 3D modeling software (such as SolidWorks, Pro / E, UG, etc.) to accurately construct a 3D model of the impeller based on the design parameters and geometric shape of the impeller, which can fully reflect the geometric characteristics of the impeller.

[0047] S12. Select the surface to be welded at the connection between the blade and the wheel cover in the model, extract its contour line and project it onto a plane; through the measurement and extraction functions of the software, the contour line of the surface to be welded can be accurately obtained and projected onto a plane, generating a two-dimensional template that highly matches the shape of the surface to be welded, providing precise guidance for subsequent solder cutting, reducing human measurement errors and improving the accuracy of the template.

[0048] S13. Increase the amount of material along the profile toward the periphery to generate a solder cutting template. This ensures that the solder completely covers the surface to be welded during welding, with sufficient margin to fill the weld. The increased-volume cutting template ensures that the solder adheres closely to the surface to be welded during welding, while also preventing welding defects caused by insufficient solder.

[0049] As another specific embodiment, in S12, projection is performed perpendicular to the line connecting the vertices and the bottom points of the wheel cover curved surface. The surface connecting the vertices and the bottom points refers to a straight line passing through the vertices and the bottom points, and this straight line is used as the plane determined by the normal direction of the projection surface. This plane provides a relatively stable reference direction, which is highly consistent with the natural direction of the profile line on the curved surface. By selecting the surface connecting the vertices and the bottom points as the projection surface, the deviation between the projection direction and the profile line direction can be reduced, and the change in the projection length can be effectively reduced, making the projection length closer to the actual length compared to other directions. This method facilitates the selection of the projection surface. In addition, the best projection surface can also be found through software functions.

[0050] As another specific implementation, in S12, the profile is extended by 5-10 mm to both ends along the length direction. When the profile is projected, its curved surface will cause the projection length to be shortened to a certain extent. In the actual welding process, the profile needs to cover the entire area to be welded, and a certain margin is required to ensure the reliability of welding. By extending the profile by 5-10 mm to both ends along the length direction, it can be ensured that the solder can fully cover the area to be welded during the welding process, avoiding welding defects caused by insufficient solder. Specifically, after extracting the profile of the surface to be welded at the connection between the blade and the wheel cover, the profile is extended by 5-10 mm to both ends along the length direction of the profile using three-dimensional software. The extended profile is projected onto a plane to generate a solder cutting template.

[0051] As another specific implementation method, in S13, a 1~3mm expansion is performed along the profile toward the periphery to generate a solder cutting template. Designing an R angle at the connection between the blade and the wheel cover can effectively disperse stress, reduce stress concentration points, and thus improve the strength and durability of the welded joint. Based on the profile, a certain amount of expansion is performed toward the periphery to ensure that the solder can cover the entire joint area during the welding process and form a smooth R angle. Specifically, the expansion size is selected according to the gap between the blade and the wheel cover, that is, the foil solder. Specifically, after extracting the profile of the surface to be welded through the three-dimensional software, the extracted profile is selected, and the offset curve function is selected to complete the 1~3mm expansion along the profile toward the periphery.

[0052] As another specific embodiment, in S2, a brazing foil with a thickness of 0.03-0.05 mm is selected and cut according to a cutting template. This brazing foil has excellent flexibility and maneuverability, adapting to complex curved surfaces. Furthermore, during vacuum brazing, it melts quickly and flows evenly, filling the weld seam and ensuring the quality of the weld joint.

[0053] In another specific embodiment, the foil solder is segmented in 3D modeling software based on torsion changes. The 3D modeling software accurately models the blade geometry, including its torsion angle characteristics, and the software determines the segmentation positions of the solder based on the blade torsion angle changes. Based on the simulation results, a segmentation template for the solder is generated for actual cutting. This allows for precise determination of the solder segmentation positions, ensuring a close fit between the solder and the blade surface. Alternatively, during the actual welding process, the cut foil solder is first test-fitted to the blade surface, and the segmentation positions are determined based on the actual fit of the solder on the blade surface. This actual fit allows for intuitive observation of the fit between the solder and the blade surface, ensuring the rationality of the segmentation. The segmentation positions can also be flexibly adjusted based on the actual fit to accommodate different blade geometries, allowing for intuitive observation and optimization of the solder fit. Specifically, the cut foil solder is divided into 3 to 5 segments based on the blade torsion angle characteristics. The segmentation positions are determined based on the blade geometry and torsion angle changes. Typically, a blade can be divided into a tip section, a middle section, and a root section, or can be divided into more sections according to the twist angle of the blade.

[0054] As another specific embodiment, in S3, the cut foil solder is applied to the blade surface to be welded, section by section, ensuring that the solder edge aligns with the margins reserved for the profile. This ensures that the solder edge aligns with the margins reserved for the profile, providing sufficient space for the solder to flow during the welding process and preventing welding defects caused by insufficient solder. Furthermore, the consistency between the actual bonding process and the extracted profile is verified, enabling immediate identification and resolution of problems and reducing welding defects.

[0055] As another specific embodiment, in S3, the solder is fixed using low-current resistance spot welding, and each section of solder is spot welded in sequence along its outer contour, with the spot welding spacing controlled at 10 to 15 mm. Low-current resistance spot welding can avoid excessive thermal impact on the solder and reduce deformation or damage caused by thermal stress. Each section of solder is spot welded in sequence along its outer contour, which can ensure that the solder is evenly fixed on the blade surface and avoid welding defects caused by local loose fixation. The spot welding spacing is controlled at 10 to 15 mm, which can ensure the fixing effect of the solder without causing excessive thermal impact on the solder, thereby avoiding deformation or damage caused by thermal stress.

[0056] As another specific embodiment, in S4, after the brazing material is fixed, the blade and the wheel cover are tested and the wheel cover is rotated and adjusted to ensure a uniform assembly gap. By rotating the wheel cover, the assembly gap between the blade and the wheel cover can be visually observed to ensure a uniform gap in all directions.

[0057] As another specific embodiment, in S6, the assembled blades, wheel covers and fixtures are placed in a vacuum furnace and heated according to the set brazing parameters, with a temperature range of 1000-1100°C and a vacuum degree of less than 10 -2 Pa. Within this temperature range, the solder can fully melt and flow to fill the weld. It can also avoid the degradation of material properties caused by overheating or overburning of the solder, ensuring the quality and strength of the welded joint. The vacuum degree is better than 10 -2 Pa can effectively reduce impurity gases in the furnace, avoid oxidation and contamination, and improve the purity and strength of the welded joint. It can also reduce the formation of pores during welding and improve density.

[0058] This solution uses vacuum brazing after pre-setting the brazing filler metal. The joint area is free of visible pores or inclusions, resulting in high-quality brazing. Ultrasonic C-scan results indicate a brazing rate exceeding 95%. This method has successfully addressed weld defects caused by insufficient brazing filler metal in the manufacture of supercritical CO2 compressor impellers.

[0059] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A brazing method for a closed impeller with a narrow curvature flow channel, characterized in that: The following steps are involved: S1. Extract the surface profile of the blade and shroud joint to be welded based on the 3D model and generate a solder cutting template: S11. Create a three-dimensional model of the impeller using three-dimensional modeling software; S12. Select the surface to be welded at the connection between the blade and the wheel cover in the model, extract its profile, and project it onto a plane perpendicular to the line connecting the vertex and the bottom point of the wheel cover curved surface to generate a two-dimensional template that highly matches the shape of the surface to be welded; S13, increasing the amount of material along the profile toward the periphery to generate a solder cutting template; S2. Cutting the solder foil strip according to the solder cutting template and dividing it into sections: the solder foil strip is divided into sections according to the torsion change in the 3D modeling software; S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade; S4. Test-assemble and adjust the relative position of the blades and wheel cover to ensure uniform assembly clearance; S5. Use fixtures to fix the blades and wheel covers; S6. Perform vacuum brazing.

2. The brazing method according to claim 1, wherein: In S12, the length of the profile is extended 5-10 mm toward both ends.

3. The brazing method according to claim 1, wherein: In S13, a 1 to 3 mm increase in size is made along the profile toward the periphery to generate a solder cutting template.

4. The brazing method according to claim 1, wherein: In S2, a foil solder with a thickness of 0.03 to 0.05 mm is selected and cut according to the cutting template.

5. The brazing method according to claim 1, wherein: In S3, the cut foil solder is attached to the surface of the blade to be welded section by section, ensuring that the edge of the solder is consistent with the margin reserved by the profile.

6. The brazing method according to claim 1, wherein: In S3, low-current resistance spot welding is used to fix the solder. Each section of solder is spot welded along its outer contour in sequence, and the spot welding spacing is controlled at 10~15mm.

7. The brazing method according to claim 1, wherein: In S6, the assembled blades, wheel covers and fixtures are placed in a vacuum furnace and heated according to the set brazing parameters. The temperature range is 1000~1100℃ and the vacuum degree is less than 10 -2 Pa.

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