Brazing method for closed impeller with curvature narrow runner

Abstract

The invention discloses a brazing method for a closed impeller with a curvature narrow runner, which comprises the following steps of: S1, extracting a molded line of a surface to be welded at the joint of a blade and an impeller cover based on a three-dimensional model, and generating a brazing filler metal cutting template; s2, foil strip brazing filler metal is cut and segmented according to the brazing filler metal cutting template; s3, the cut foil strip brazing filler metal is attached to the to-be-welded surface of the blade, and the foil strip brazing filler metal and the blade are fixed through spot welding; s4, trial assembly is conducted, the relative positions of the blades and the wheel cover are adjusted, and it is ensured that assembly gaps are uniform; s5, the blade and the wheel cover are fixed through a tool clamp; and S6, vacuum brazing is conducted. The closed impeller with the curvature narrow flow channel can be filled with brazing filler metal accurately and evenly, and the final joint quality is guaranteed.

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 closed impellers with curvature are widely used in the fields of aviation, energy and industrial compressors. Due to their complex geometric shapes, these impellers are usually manufactured by splitting and then connecting.

[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: 1. The narrow flow channel and the twisted shape of the blades prevent the welding gun from penetrating deeply.

[0004] 2. Fusion welding can easily cause deformation of the joint area, affecting the balance performance of the impeller.

[0005] The vacuum brazing process is the first choice for its advantages of uniform heating, small deformation, and the ability to complete multiple welds at the same time. However, the key to this process lies in the pre-setting of the brazing material before welding. Especially for structures with curvature, how to accurately and evenly fill the brazing material is the core issue that affects the quality of the final joint. Summary of the invention

[0006] The purpose of the present invention is to provide a brazing method for a closed impeller with a narrow flow channel and a curvature in order to solve the above-mentioned problems, so as to accurately and evenly fill the closed impeller with a narrow flow channel and a curvature with brazing material to ensure the quality of the final joint.

[0007] The technical solution adopted by the present invention is as follows: A brazing method for a closed impeller with a curvature narrow flow channel comprises the following steps: S1, extracting the surface profile of the connection between the blade and the wheel cover to be welded based on the three-dimensional model, and generating a solder cutting template; S2, cutting the solder foil strip into sections according to the solder cutting template; S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade to fix them; S4. Test-assemble and adjust the relative position of the blade and the wheel cover to ensure uniform assembly clearance; S5. Fix the blade and the wheel cover with a fixture; S6. Perform vacuum brazing.

[0008] Optionally, S1 comprises the following steps: S11. Using 3D modeling software to create a 3D model of the impeller; S12, selecting the surface to be welded at the connection between the blade and the wheel cover in the model, extracting its profile and projecting it onto the plane; S13, increasing the volume along the profile line toward the periphery to generate a solder cutting template.

[0009] Optionally, in S12, projection is performed perpendicular to the line connecting the vertex and the bottom point of the wheel cover surface.

[0010] Optionally, in S12, the length of the profile is extended by 5-10 mm towards both ends.

[0011] Alternatively, in S13, a 1 to 3 mm increase in volume is made along the profile toward the periphery to generate a solder cutting template.

[0012] Alternatively, in S2, a foil strip solder having a thickness of 0.03 to 0.05 mm is selected and cut according to a cutting template.

[0013] Optionally, in S2, the foil solder is segmented in the three-dimensional modeling software according to the torsion change; or, the cut foil solder is first tried to fit the blade surface, and the segmentation position is determined according to the actual fitting of the solder on the blade surface.

[0014] Alternatively, in S3, the cut foil strip solder is attached to the surface of the blade to be welded section by section, ensuring that the solder edge is consistent with the reserved margin of the profile.

[0015] Alternatively, in S3, low current resistance spot welding is used to fix the solder, and each section of solder is spot welded along its outer contour in sequence, with the spot welding spacing controlled at 10-15 mm.

[0016] Alternatively, 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℃ and a vacuum degree of less than 10 -2 Pa.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The present invention provides a brazing method for a closed impeller with a narrow curvature flow channel. Through precise brazing material presetting and vacuum brazing process, 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

[0018] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 It is a schematic diagram of the process of this brazing method.

[0019] Figure 2 It is a schematic diagram of the solder cutting template. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0021] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0022] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0023] A brazing method for a closed impeller with a curvature narrow flow channel, such as Figure 1 As shown, the following steps are included: S1. Extract the surface profile of the blade and the wheel cover to be welded based on the 3D model, and generate a solder cutting template, such as Figure 2 As shown; S2, cutting the solder foil strip into sections according to the solder cutting template; S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade to fix them; S4. Test-assemble and adjust the relative position of the blade and the wheel cover to ensure uniform assembly clearance; S5. Fix the blade and the wheel cover with a fixture; S6. Perform vacuum brazing.

[0024] The blades of impellers usually have complex curvatures and torsional shapes, which are difficult to accurately handle with traditional manual measurement and template making methods. However, 3D modeling software can easily handle these complex surfaces and ensure 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 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. The fit between the solder and the complex surface is ensured by prestressed forming technology. Vacuum brazing achieves uniform filling of the solder and ensures the strength and sealing of the welded joint. It provides a uniform heating environment, reduces deformation, and completes the welding of multiple welds at the same time, improving welding efficiency and joint quality.

[0025] 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 The foil brazing material has good flexibility and plasticity and can adapt to the complex curvature of the blade. The brazing foil strip suitable for the curved surface shape of the blade can be accurately cut out using a cutting template, and the brazing material can be cut in sections according to the torsion angle of the blade. Each section of the brazing material can better adapt to the local torsion angle of the blade to ensure the full fit of the brazing material on the complex geometric surface. S3 fits the brazing foil strip to the blade and temporarily fixes the brazing material to the blade by spot welding, which ensures the position stability of the brazing material during the welding process and avoids the 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. The uniform assembly gap helps the brazing material to flow evenly during the welding process and avoids welding defects caused by uneven gaps. The S5 fixture can provide sufficient rigidity to ensure the accurate position of the blades and wheel cover during vacuum brazing and prevent relative movement during welding. The S6 vacuum brazing process has a uniform heating process, which can reduce thermal stress and deformation. The brazing material melts and fills the connection gap between the blade and the wheel cover, and completely covers it through capillary action to form a uniform and dense connection joint. The vacuum environment reduces the formation of oxides and improves the strength and reliability of the welded joint. Uniform heating further reduces welding deformation and ensures the balanced performance of the impeller.

[0026] As another specific implementation, S1 includes the following steps: S11. Use 3D modeling software to build a 3D model of the impeller (including blades and wheel cover); through 3D modeling software (such as SolidWorks, Pro / E, UG, etc.), accurately construct a 3D model of the impeller according to the design parameters and geometric shape of the impeller, which can fully reflect the geometric characteristics of the impeller.

[0027] 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 the 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 the plane, generating a two-dimensional template that is highly matched with 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.

[0028] S13, increase the amount along the profile line toward the periphery to generate a solder cutting template to ensure that the solder can completely cover the surface to be welded during the welding process and have enough margin to fill the weld. The cutting template after increasing the amount can ensure that the solder fits tightly with the surface to be welded during the welding process, while avoiding welding defects caused by insufficient solder.

[0029] As another specific implementation, in S12, projection is performed perpendicular to the line connecting the vertices and the bottom points of the wheel cover curved surface. The vertex and bottom point connecting surface refers to a straight line passing through the vertex and the bottom point, 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 type line on the curved surface. By selecting the vertex and bottom point connecting surface as the projection surface, the deviation between the projection direction and the type 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.

[0030] 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 three-dimensional software is used to extend the profile by 5-10 mm to both ends along the length direction of the profile. The extended profile is projected onto a plane to generate a solder cutting template.

[0031] As another specific implementation, in S13, a 1-3 mm release is made 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 and reduce stress concentration points, thereby improving the strength and durability of the welded joint. A certain amount of release is made toward the periphery on the basis of the profile to ensure that the solder can cover the entire corner area during the welding process and form a smooth R angle. Specifically, the release 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, select the extracted profile, select the offset curve function, and complete the release of 1-3 mm along the profile toward the periphery.

[0032] As another specific implementation, in S2, a foil solder with a thickness of 0.03-0.05 mm is selected and cut according to the cutting template. The foil solder with a thickness of 0.03-0.05 mm has good flexibility and operability, and can adapt to the shape of complex curved surfaces. At the same time, it can melt quickly and flow evenly during the vacuum brazing process, fill the weld, and ensure the quality of the welded joint.

[0033] As another specific implementation, the foil solder is segmented in the three-dimensional modeling software according to the torsion change; wherein, the geometric shape of the blade is accurately modeled using the three-dimensional modeling software, including its torsion angle characteristics, and the segmentation position of the solder is determined in the software according to the torsion angle change of the blade; according to the simulation results, a segmentation template of the solder is generated for actual cutting. The segmentation position of the solder can be accurately determined to ensure that the solder is closely fitted to the surface of the blade. Alternatively, in the actual welding process, the cut foil solder is first tried to fit the blade surface, and the segmentation position is determined according to the actual fitting of the solder on the blade surface. Through the actual fitting, the fitting of the solder and the blade surface can be intuitively observed to ensure the rationality of the segmentation. And the segmentation position can be flexibly adjusted according to the actual fitting situation, adapted to different blade geometries, and the fitting effect of the solder can be intuitively observed and optimized. Specifically, according to the torsion angle characteristics of the blade, the cut foil solder is cut into 3 to 5 segments. The position of the segment is determined according to the geometry of the blade and the change of the torsion angle. Typically, the blade can be divided into a tip section, a middle section and a root section, or into more sections according to the change in the twist angle of the blade.

[0034] As another specific implementation, in S3, the cut foil solder is attached to the blade surface to be welded section by section, ensuring that the solder edge is consistent with the reserved margin of the profile. Ensuring that the solder edge is consistent with the reserved margin of the profile can provide sufficient flow space for the solder during the welding process, avoiding welding defects caused by insufficient solder, and at the same time checking whether the actual attachment process is consistent with the extracted profile, so as to immediately discover and solve problems and reduce welding defects.

[0035] As another specific implementation, in S3, the solder is fixed by low-current resistance spot welding, and each section of solder is spot welded in sequence along its outer contour, and the spot welding spacing is controlled at 10-15 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 uniform fixation of the solder on the blade surface and avoid welding defects caused by local loose fixation. The spot welding spacing is controlled at 10-15 mm, which can ensure the fixing effect of the solder without causing excessive thermal impact on the solder, avoiding deformation or damage caused by thermal stress.

[0036] As another specific implementation, in S4, after the solder is fixed, the blade and the wheel cover are assembled, and the wheel cover is rotated to adjust the position to ensure that the assembly gap is uniform. By rotating the wheel cover, the assembly gap between the blade and the wheel cover can be visually observed to ensure that the gap is uniform in all directions.

[0037] As another specific implementation, 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 brazing filler metal can fully melt and flow to fill the weld. It can also avoid the degradation of material properties or overburning of the brazing filler metal caused by overheating, thus ensuring the quality and strength of the welded joint. The vacuum degree is better than 10 -2 Pa can effectively reduce the impurity gas in the furnace, avoid oxidation and pollution, and improve the purity and strength of the welded joint. It can also reduce the generation of pores during welding and improve density.

[0038] In this scheme, vacuum brazing is performed after brazing filler metal is pre-set. There are no obvious pores or inclusions in the joint area, and the brazing quality is high. The ultrasonic C-scan results show that the brazing rate can reach more than 95%. In the manufacture of supercritical CO2 compressor impellers, this method successfully solves the problem of welding defects caused by insufficient brazing filler metal filling.

[0039] The present invention is not limited to the above-mentioned 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, extracting the surface profile of the connection between the blade and the wheel cover to be welded based on the three-dimensional model, and generating a solder cutting template; S2, cutting the solder foil strip into sections according to the solder cutting template; S3, attaching the cut foil solder to the surface of the blade to be welded, and spot welding the foil solder and the blade to fix them; S4. Test-assemble and adjust the relative position of the blade and the wheel cover to ensure uniform assembly clearance; S5. Fix the blade and the wheel cover with a fixture; S6. Perform vacuum brazing.

2. The brazing method according to claim 1, characterized in that: S1 includes the following steps: S11. Using 3D modeling software to create a 3D model of the impeller; S12, selecting the surface to be welded at the connection between the blade and the wheel cover in the model, extracting its profile and projecting it onto the plane; S13, increasing the volume along the profile line toward the periphery to generate a solder cutting template.

3. The brazing method according to claim 2, characterized in that: In S12, projection is performed perpendicular to the line connecting the vertex and the bottom point of the wheel cover surface.

4. The brazing method according to claim 2, characterized in that: In S12, the length of the profile is extended by 5-10 mm toward both ends.

5. The brazing method according to claim 2, characterized in that: In S13, a 1 to 3 mm increase in volume is made along the mold line toward the periphery to generate a solder cutting template.

6. The brazing method according to claim 2, characterized in that: In S2, a foil solder with a thickness of 0.03-0.05 mm is selected and cut according to the cutting template.

7. The brazing method according to claim 1, characterized in that: In S2, the foil solder is segmented in the three-dimensional modeling software according to the torsion change; or, the cut foil solder is firstly tried to fit the blade surface, and the segmentation position is determined according to the actual fitting of the solder on the blade surface.

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

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

10. 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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