Manufacturing method of sheet metal centrifugal wind wheel and sheet metal centrifugal wind wheel

Abstract

The application discloses a manufacturing method of a sheet metal centrifugal wind wheel and the sheet metal centrifugal wind wheel. The wind wheel comprises a wheel disc, a wheel cover and a plurality of blades. The plurality of blades are installed between the wheel disc and the wheel cover. The blade comprises an inlet edge, an outlet edge, a blade root and a blade top. The manufacturing method is that the inlet edge of the blade is offset by an equal distance a to one side of the outlet edge, a folding line is formed, the folding line and the inlet edge are surrounded on the blade from the blade root to the blade top to form a front edge part, and the front edge part is bent by a certain angle f to the center of the wind wheel rotating shaft L. The method stabilizes the blade structure modeling, suppresses the rebound effect, reduces the deviation between the actual blade center line and the designed blade center line, ensures that the inlet airflow angle of the rebounded blade is a positive angle of attack, improves the static pressure efficiency of the blade in a large flow interval, reduces the number of correction molds, saves the manufacturing cost and the mold cost, reduces uncontrollable factors, and guarantees the final blade performance and the delivery period of the finished product.

Description

Technical fields:

[0001] This invention relates to a method for manufacturing a sheet metal centrifugal impeller and the sheet metal centrifugal impeller itself. Background technology:

[0002] like Figure 1 The existing sheet metal rearward centrifugal impeller consists of a disc 1a, a cover 2a, and several blades 3a, formed by sheet metal stamping. After stamping, due to the elastic properties of the material, there will be a springback phenomenon, which will cause the actual blade centerline to deviate from the originally designed blade centerline. See the following for a detailed description:

[0003] The blades of a centrifugal wind turbine are a key component, directly affecting the turbine's efficiency, and the blade centerline is an important geometric concept characterizing blade performance. For a centrifugal wind turbine, the blade cross-section can be obtained by cutting the turbine along any plane perpendicular to the axis of rotation between the rotor disk and the shroud, as shown in [reference needed]. Figure 2 As shown, countless inscribed circles of the blade's outline can be drawn within the blade's cross-section. The line connecting the centers of all these inscribed circles forms the blade's centerline. Figure 3 As shown, the blade centerline is the basic geometric unit of the blade. The blade can be regarded as being formed by the accumulation of countless different blade centerlines on various cross sections from the blade root to the blade tip.

[0004] like Figure 4As shown, the blade's geometric parameters are defined as follows: the endpoint in the direction of airflow is the starting point of the blade centerline, and the endpoint in the direction of air departure is the ending point of the blade centerline. Based on the concepts of absolute velocity, relative velocity, and entrainment velocity in theoretical physics, it is known that the air will undergo relative motion along the blade centerline within the wind turbine. Using the Earth as the absolute coordinate system, the absolute velocity vector of the air can be easily decomposed according to the parallelogram theorem, allowing for the easy drawing of the starting and ending points of the blade centerline, as well as the relationships between various velocity vectors during the process. The air velocity vectors at the starting and ending points of the centerline directly determine the blade's work capacity. For the starting point of the centerline: C1 is the absolute velocity of the airflow at the blade inlet, W1 is the relative velocity of the airflow at the blade inlet, and U1 is the entrainment velocity at the starting point of the centerline, i.e., the circumferential velocity at that point. For the ending point of the centerline: C2 is the absolute velocity of the airflow at the blade outlet, W2 is the relative velocity of the airflow at the blade outlet, and U2 is the entrainment velocity at the ending point of the centerline, i.e., the circumferential velocity at that point. Therefore: the angle between the opposing directions of W1 and U1 is the blade inlet angle; the angle between the opposing directions of W2 and U2 is the blade outlet angle. Blade springback phenomenon: Blades are manufactured using sheet metal stamping, a metal processing method based on the plastic deformation of metal. It utilizes molds and stamping equipment to apply pressure to sheet metal, causing plastic deformation or separation to obtain parts (stamped parts) with specific shapes, dimensions, and properties. Due to the elastic modulus (inherent physical property) of the sheet metal, the stamped part exhibits internal stress after plastic deformation. After the stamped part is left to stand for a period of time, this internal stress is released. Areas with less plastic deformation tend to "revert" to their original state; this phenomenon is called springback. For blades manufactured using sheet metal stamping, the plastic deformation is small, making springback very pronounced. Springback causes the blade shape to deviate from the designed shape; essentially, the blade's centerline deviates from the original design.

[0005] like Figure 5 As shown, the dashed blade centerline represents the designed shape, while the solid blade centerline represents the rebounded shape. Based on the definitions of blade geometry parameters above, the absolute positions of the centerline's starting and ending points change after rebound. Macroscopically, this manifests as a smaller blade inlet angle and a larger blade outlet angle. Consequently, the inlet airflow vector relationship directly related to the centerline's starting point changes, as does the outlet airflow vector relationship directly related to the centerline's ending point. Thus, the blade's performance is completely altered, deviating entirely from the original design. The rebound further reduces the blade's inlet angle. A smaller inlet angle weakens the rotor's work capacity in the high-flow-rate range and reduces the blade's static pressure efficiency.

[0006] To ensure that the actual blade centerline matches the original design as closely as possible, the stamping die needs to be modified multiple times, taking into account the material's elastic properties and stamping deformation. This modification process heavily relies on relevant technological experience, and the results are still subject to some deviation. Because the relationship between the material's elastic properties, stamping deformation, and springback is complex, it cannot be predicted through calculations or simulations. Therefore, in actual production, current technology cannot guarantee that the blade performance will perfectly match the design performance. Furthermore, the time-consuming and uncontrollable modification process makes it difficult to guarantee the delivery time of the finished product. Summary of the Invention:

[0007] One objective of this invention is to provide a manufacturing method for a sheet metal centrifugal impeller and a sheet metal centrifugal impeller, which solves the technical problem that in the prior art, after the blades are stamped, there will be a springback phenomenon due to the elastic properties of the material, which causes the actual blade centerline to deviate from the originally designed blade centerline, resulting in a smaller blade inlet angle. This requires multiple corrections of the stamping die, and the die correction process is time-consuming and not entirely controllable, making it difficult to guarantee the delivery time of the finished product.

[0008] The objective of this invention is achieved through the following technical solution.

[0009] A method for manufacturing a sheet metal centrifugal impeller, the impeller comprising a disc, a cover, and several blades, the blades being installed between the disc and the cover, the blades comprising an inlet edge, an outlet edge, a root, and a tip, characterized in that: the manufacturing method involves offsetting the inlet edge of the blade to one side of the outlet edge by an equal distance 'a' to form a folded edge line, forming a leading edge portion on the blade from the root to the tip, between the folded edge line and the inlet edge, and bending the leading edge portion towards the center of the impeller's rotation axis L at a certain angle 'f'.

[0010] The value of the equal distance 'a' mentioned above ranges from 5mm to 15mm; the value of the angle 'f' ranges from 3 degrees to 10 degrees.

[0011] The aforementioned offset of the inlet edge 1 of the blade from the outlet edge by an equal distance a means that each point B on the inlet edge 1 is offset from the blade centerline K corresponding to point B by an equal distance a from the outlet edge.

[0012] The blade centerline mentioned above refers to the blade cross-section obtained by taking a section of the wind turbine from any plane S perpendicular to the rotation axis L between the turbine disk and the turbine cover. Within the blade cross-section, countless inscribed circles of the blade profile can be drawn. The line connecting the centers of all the inscribed circles is the blade centerline K.

[0013] The intersection of the plane S and the rotation axis L is the center O, and the intersection of the blade centerline K and the fold line is C. With point C as the center, the CB segment on the blade centerline K is rotated a certain angle f toward the center O.

[0014] A sheet metal centrifugal impeller, characterized in that it is manufactured using the aforementioned sheet metal centrifugal impeller manufacturing method.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] I. The manufacturing method of the sheet metal centrifugal impeller of the present invention can stabilize the blade structure and suppress the rebound effect caused by the release of material stress, thereby reducing the deviation between the actual blade centerline and the designed blade centerline in the produced product.

[0017] Second, by changing the blade centerline starting point parameter through the manufacturing method of the sheet metal centrifugal impeller of the present invention, the blade inlet angle is increased, which can ensure that the inlet airflow angle of the blade after rebound is a positive angle of attack, thereby increasing the blade's work capacity in the high flow range and improving the blade static pressure efficiency in the high flow range.

[0018] Third, the manufacturing method of the sheet metal centrifugal impeller of the present invention reduces the number of times the mold is modified, saves manufacturing and mold costs, greatly increases the efficiency of mold opening, reduces uncontrollable factors, and ensures the final blade performance and product delivery time.

[0019] IV. Other advantages of the present invention are described in detail in the Embodiments section. Attached image description:

[0020] Figure 1 This is a schematic diagram of the structure of a wind turbine in the existing technology;

[0021] Figure 2 It is a cross-sectional view of the wind turbine taken from a plane perpendicular to the axis of rotation in the prior art;

[0022] Figure 3 yes Figure 2 A magnified view of part A;

[0023] Figure 4 This is a schematic diagram illustrating the definition of geometric parameters of the blade centerline in existing technology;

[0024] Figure 5 This is a comparison diagram of the blade centerline after springback in existing technology and the original design;

[0025] Figure 6 This is a schematic diagram of the sheet metal centrifugal impeller of the present invention being cut by a plane S perpendicular to the axis of rotation L;

[0026] Figure 7 This is a schematic diagram of the sheet metal centrifugal impeller of the present invention after being cut by plane S;

[0027] Figure 8 yes Figure 7 A magnified view of part E;

[0028] Figure 9 This is a perspective view of the blades of the sheet metal centrifugal impeller of the present invention;

[0029] Figure 10 This is a schematic diagram of the blade centerline of the sheet metal centrifugal impeller of the present invention;

[0030] Figure 11 This is a schematic diagram of a point B on the inlet edge of the blade of the sheet metal centrifugal impeller of the present invention and the corresponding CB segment on the blade centerline bent at an angle towards the center O. Detailed implementation method:

[0031] The present invention will now be described in further detail through specific embodiments and in conjunction with the accompanying drawings.

[0032] Example 1:

[0033] like Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 As shown, this embodiment provides a method for manufacturing a sheet metal centrifugal impeller. The impeller comprises a disc 200, a cover 300, and several blades 100. The blades 100 are installed between the disc 200 and the cover 300. Each blade 100 includes an inlet edge 1, an outlet edge 2, a blade root 3, and a blade tip 4. The manufacturing method is characterized in that the inlet edge 1 of the blade is offset by an equal distance a to the outlet edge 2 to form a folded edge line 5. From the blade root 3 to the blade tip 4, the folded edge line 5 and the inlet edge 1 form a leading edge 6 on the blade 100. The leading edge 6 is then bent at a certain angle f toward the center of the impeller rotation axis L.

[0034] The value of the equal distance 'a' mentioned above ranges from 5mm to 15mm; the value of the angle 'f' ranges from 3 degrees to 10 degrees.

[0035] The aforementioned offset of the inlet edge 1 of the blade from the outlet edge 2 by an equal distance a means that each point B on the inlet edge 1 is offset from the blade centerline K corresponding to point B by an equal distance a from the outlet edge.

[0036] The blade centerline mentioned above refers to the blade cross-section obtained by cutting the wind turbine using any plane S perpendicular to the rotation axis L of the wheel disk 200 and wheel cover 300. Within the blade cross-section, countless inscribed circles of the blade profile can be drawn. The line connecting the centers of all the inscribed circles is the blade centerline K.

[0037] The intersection of the plane S and the rotation axis L is the center O, and the intersection of the blade centerline K and the fold line 5 is C. With point C as the center, the CB segment on the blade centerline K is rotated a certain angle f toward the center O.

[0038] The blade centerline K is an important geometric concept characterizing the performance of wind turbine blades. For centrifugal wind turbines, the blade cross-section can be obtained by taking a section of the wind turbine from any plane perpendicular to the axis of rotation L between the rotor disk 200 and the rotor cover 300. Within the blade cross-section, countless inscribed circles of the blade profile can be drawn. The line connecting the centers of all the inscribed circles is the blade centerline. The blade centerline is the basic geometric unit of the blade. The blade can be regarded as being formed by the accumulation of countless different blade centerlines on the cross-section from the blade root to the blade tip.

[0039] The innovation of this solution lies in the 6-directional bending of the rotor's rotation axis L at the leading edge. Its core technology utilizes a novel structural design to alter the airflow characteristics at the blade's centerline K, thus addressing the discrepancy between the actual sheet metal stamping of the blades and the design specifications.

[0040] This innovative method addresses the following issues:

[0041] First, it stabilizes the blade structure and suppresses the rebound effect caused by the release of material stress, thereby reducing the deviation between the actual blade centerline and the designed blade centerline.

[0042] Secondly, by changing the centerline starting point parameter of the blade, the blade inlet angle is increased, which ensures that the inlet airflow angle of the blade after rebound is a positive angle of attack, thereby increasing the blade's work capacity in the high flow range and thus improving the blade's static pressure efficiency in the high flow range.

[0043] Third, it reduces the number of times the mold needs to be modified, saves manufacturing and mold costs, greatly increases the efficiency of mold opening, reduces uncontrollable factors, and ensures the final blade performance and product delivery time.

[0044] The present invention relates to a backward centrifugal impeller, but the technology can be applied to other sheet metal impeller forms, including but not limited to axial flow impellers, mixed flow impellers, forward centrifugal impellers, and other forms.

[0045] Example 2:

[0046] A sheet metal centrifugal impeller, characterized in that it is manufactured using the sheet metal centrifugal impeller manufacturing method described in Example 1.

[0047] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited thereto. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention are equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A method for manufacturing a sheet metal centrifugal impeller, the impeller comprising a disc (200), a cover (300), and a plurality of blades (100), wherein the plurality of blades (100) are installed between the disc (200) and the cover (300), and the blades (100) comprising an inlet edge (1), an outlet edge (2), a blade root (3), and a blade tip (4), characterized in that: The manufacturing method involves offsetting the inlet edge (1) of the blade by an equal distance a to the outlet edge (2), forming a folded edge line (5). From the blade root (3) to the blade tip (4), the folded edge line (5) and the inlet edge (1) form a leading edge (6) on the blade (100). The leading edge (6) is bent at a certain angle f toward the center of the rotor rotation axis L to increase the blade inlet angle. This ensures that the inlet airflow angle of the blade after rebound is a positive angle of attack, thereby increasing the blade's work capacity in the high flow range and improving the blade's static pressure efficiency in the high flow range.

2. A method for manufacturing a sheet metal centrifugal impeller according to claim 1, characterized in that: The range of the equal distance 'a' is 5mm-15mm; the range of the angle 'f' is 3 degrees-10 degrees.

3. A method for manufacturing a sheet metal centrifugal impeller according to claim 1 or 2, characterized in that: The offset of the inlet edge (1) of the blade to the outlet edge (2) by an equal distance a means that each point B on the inlet edge (1) is offset by an equal distance a on the blade centerline K corresponding to point B to the outlet edge (2).

4. The manufacturing method of a sheet metal centrifugal impeller according to claim 3, characterized in that: The blade centerline refers to the blade cross-section obtained by cutting the wind turbine on any plane S perpendicular to the rotation axis L between the wheel disk (200) and the wheel cover (300). Within the blade cross-section, countless inscribed circles of the blade profile can be drawn. The line connecting the centers of all the inscribed circles is the blade centerline K.

5. The method for manufacturing a sheet metal centrifugal impeller according to claim 4, characterized in that: The intersection of plane S and rotation axis L is center O, and the intersection of blade centerline K and fold line (5) is C. With point C as the center, the CB segment on blade centerline K rotates a certain angle f toward center O.

6. A sheet metal centrifugal impeller, characterized in that: It is manufactured using the sheet metal centrifugal impeller manufacturing method described in any one of claims 1 to 5.

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