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. A curve AG is formed from a vertex A to a point G on the outlet edge. A curve AH is formed from the vertex A to a point H on the blade top. A crease line is formed by the point H and the point G on the blade. The curve AG, the curve AH and the crease line GH form an angular position bending part on the blade. The angular position bending part is bent towards the center of a rotating shaft L of the wind wheel. The blade structure modeling is stabilized, the rebound effect is inhibited, the deviation between an actual blade profile and a designed blade profile is reduced, the outlet airflow angle of the rebounded blade is ensured to meet the original design, the number of correction molds is reduced, the manufacturing cost and the mold cost are saved, uncontrollable factors are reduced, and the final blade performance and the product delivery period are ensured.

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 backward 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 profile to deviate from the original design blade profile. 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 profile is an important geometric concept characterizing the performance of the blades. For a centrifugal wind turbine, the blade cross-section can be obtained by taking a section of the turbine from any plane perpendicular to the axis of rotation near the bottom of the turbine, as shown in [reference needed]. Figure 2 As shown, countless inscribed circles of the blade profile can be drawn within the blade cross-section. The line connecting the centers of all these inscribed circles forms the blade profile (or blade centerline). Figure 3 As shown, the blade profile is the basic geometric unit of a blade. A blade can be viewed as a collection of countless different blade profiles on various cross sections stacked from the blade root to the blade tip.

[0004] like Figure 4As shown, the blade geometry parameters are defined as follows: the endpoint in the direction of airflow is the starting point of the blade profile, and the endpoint in the direction of air departure is the ending point of the blade profile. 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 profile 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 profile, as well as the relationships between various velocity vectors throughout the process. The air velocity vectors at the starting and ending points of the blade profile directly determine the blade's work capacity. For the starting point of the blade profile: 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 blade profile, i.e., the circumferential velocity at that point. For the ending point of the blade profile: 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 blade profile, i.e., the circumferential velocity at that point. Therefore: the angle between the opposite directions of W1 and U1 is the blade inlet angle; the angle between the opposite directions of W2 and U2 is the blade outlet angle. Blade springback phenomenon: Blades are made using sheet metal stamping, a metal processing method based on the plastic deformation of metal. It uses molds and stamping equipment to apply pressure to the sheet metal, causing plastic deformation or separation, thereby obtaining parts (stamped parts) with specific shapes, dimensions, and properties. Due to the elastic modulus (inherent physical property) of the sheet metal, the stamped part after plastic deformation has internal stress. After the stamped part is left to stand for a period of time, the internal stress will be released. Areas with small plastic deformation will tend to "revert" to the original state of the sheet metal; this phenomenon is called springback. For blades made using sheet metal stamping, the plastic deformation is small, and the springback phenomenon is very obvious. Springback causes the blade shape to deviate from the design shape; essentially, the blade profile deviates from the original design.

[0005] like Figure 5 As shown, the dashed blade profile represents the designed shape, while the solid blade profile represents the shape after springback. Based on the definitions of blade geometry parameters above, the absolute positions of the starting and ending points of the blade profile change after springback. Macroscopically, this manifests as a smaller blade inlet angle and a larger blade outlet angle.

[0006] An excessively large blade exit angle will increase the wind turbine's work capacity, exceeding the original design range. While increased work capacity positively impacts the turbine's properties, it also means increased input and output power for the turbine's motor. For the established design goals, this additional input and output power may exceed the motor's permissible limits, leading to a series of adverse effects such as excessive motor temperature rise, decreased motor output efficiency, and accelerated failure of motor components. Ultimately, this manifests as decreased overall turbine efficiency, reduced operational reliability, and shortened turbine lifespan.

[0007] To ensure that the actual blade profile of the manufactured product 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:

[0008] 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 profile to deviate from the original blade profile, resulting in a larger blade exit angle that affects the efficiency and reliability of the entire fan. Therefore, it is necessary to modify the stamping die multiple times. The die modification process is time-consuming and not completely controllable, which also makes it difficult to guarantee the delivery time of the finished product.

[0009] The objective of this invention is achieved through the following technical solution.

[0010] 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 blade root, and a blade tip, characterized in that: a curve AG is formed on the outlet edge from vertex A to point G, a curve AH is formed on the blade tip from vertex A to point H, a crease line is formed on the blade connecting points H and G, and the curves AG, AH, and crease line GH form an angular bend on the blade, the angular bend bending towards the center of the impeller's rotation axis L.

[0011] The length of the curve AG mentioned above is less than or equal to 1 / 2 the length of the exit edge.

[0012] The crease lines mentioned above are formed as follows:

[0013] S1) Starting from point G and ending at vertex A, sweep along the exit edge to create path GA, drawing surface M. On each normal plane of the sweep path GA, with the end point of the blade profile as the origin and the tangent direction at the end point of the blade profile as the positive X-axis, the... Surface M Its characteristics are: its cross-sectional shape on each normal plane of the scanning path GA is a line segment; one end of the line segment is at the origin of the coordinate system, and the angle between the line segment and the positive direction of the X-axis is f;

[0014] S2) with Surface MIf the starting edge GY where point G is located is the axis, and the surface M is rotated by an angle i towards the center of the wind turbine axis L, then the surface M is extended to intersect with the blade, and the crease line GH can be obtained.

[0015] The included angle f mentioned above ranges from 3 to 10 degrees.

[0016] The angle i mentioned above ranges from 3 to 6 degrees.

[0017] The aforementioned angular bend towards the center of the wind turbine's rotation axis L refers to the bend turning towards the curved surface M and completely coinciding with the curved surface M.

[0018] The aforementioned crease line GH and exit edge intersect with several blade profile lines. Each blade profile line intersects with the crease line GH and exit edge to form a curve VO. The length of curve VO gradually increases from point G to vertex A.

[0019] A sheet metal centrifugal impeller, characterized in that it is manufactured using the aforementioned sheet metal centrifugal impeller manufacturing method.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] I. The manufacturing method of the sheet metal centrifugal impeller of the present invention can stabilize the blade structure and suppress the springback effect caused by the release of material stress, thereby reducing the deviation between the actual blade profile and the designed blade profile in the produced product.

[0022] Second, by modifying the blade profile starting point parameters and reducing the blade exit angle through the manufacturing method of the sheet metal centrifugal impeller of this invention, it is possible to ensure that the airflow angle at the blade exit after rebound conforms to the original design, thereby reducing the amplitude of the impeller exceeding the original design range and preventing the input and output power of the motor connected to the impeller from increasing beyond the motor's allowable limits. This, in turn, avoids a series of deteriorating problems such as excessive motor temperature rise, decreased motor output efficiency, and accelerated failure of motor components.

[0023] 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.

[0024] IV. Other advantages of the present invention are described in detail in the Embodiments section. Attached image description:

[0025] Figure 1 This is a schematic diagram of the structure of a wind turbine in the existing technology;

[0026] 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;

[0027] Figure 3 yes Figure 2 A magnified view of part A;

[0028] Figure 4 This is a schematic diagram illustrating the definition of geometric parameters for blade profiles in existing technologies;

[0029] Figure 5 This is a comparison diagram of the blade profile after springback in the existing technology with the original design;

[0030] Figure 6 This is a perspective view of the sheet metal centrifugal impeller of Embodiment 1 of the present invention from one angle;

[0031] Figure 7 This is a perspective view of the sheet metal centrifugal impeller of Embodiment 1 of the present invention from another angle;

[0032] Figure 8 This is an exploded view of the sheet metal centrifugal impeller of Embodiment 1 of the present invention;

[0033] Figure 9 This is a perspective view of the blades of the sheet metal centrifugal impeller according to Embodiment 1 of the present invention;

[0034] Figure 10 This is a schematic diagram of the blade after being divided into four equal parts according to Embodiment 1 of the present invention;

[0035] Figure 11 yes Figure 10 A schematic diagram marked at the exit edge;

[0036] Figure 12 This is a schematic diagram of the M-surface drawn on the blade in Embodiment 1 of the present invention;

[0037] Figure 13 This is a schematic diagram of the blade scanning at point G and intersecting with the normal plane in Embodiment 1 of the present invention;

[0038] Figure 14 This is a schematic diagram of a line segment obtained by scanning the blade at point G in Embodiment 1 of the present invention, where the M-surface intersects the normal plane.

[0039] Figure 15 This is a schematic diagram of the M-surface after rotation around the axis in Embodiment 1 of the present invention;

[0040] Figure 16 This is a schematic diagram of the blade intersecting with the extended M-surface in Embodiment 1 of the present invention;

[0041] Figure 17 This is a schematic diagram of the intersection of the blade profile and the angular bending portion in Embodiment 1 of the present invention. Detailed implementation method:

[0042] The present invention will now be described in further detail through specific embodiments and in conjunction with the accompanying drawings.

[0043] Example 1:

[0044] like Figure 6 , Figure 7 , Figure 8 , Figure 9 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 characteristic feature is that a curve AG is formed on the outlet edge 2 from vertex A to point G, and a curve AH is formed on the blade tip 4 from vertex A to point H. A crease line 102 is formed on the blade 100 by connecting points H and G. The curves AG, AH, and crease line GH form an angular bending portion 101 on the blade 100, and the angular bending portion 101 bends toward the center of the impeller's rotation axis L.

[0045] The length of the curve AG is less than or equal to 1 / 2 the length of the exit edge 2.

[0046] The following describes in detail the process of bending the corner bend 101 towards the center of the wind turbine rotating shaft L: 1: As Figure 10 As shown, the blade 100 is formed by four sides: the inlet side, the outlet side, the root side, and the tip side. From the tip side to the root side, five edges can be defined to define the blade. Four equal parts The blade profiles are as follows: a) blade profile (located at the leaf tip), b) blade profile (located at 1 / 4 of the blade length), c) blade profile (located at 2 / 4 of the blade length), d) blade profile (located at 3 / 4 of the blade length), and e) blade profile (located at the leaf root). See [link / reference]. Figure 11 As shown, the following definition applies:

[0047] The end point of the blade profile is at the exit edge. Point A ;

[0048] The endpoint of the blade profile is at the exit edge. Point B ;

[0049] The end point of the c-blade profile is at the exit edge. Point C .

[0050] 2: On curve BC A point G Starting from vertex A and ending at vertex A, draw a scan path GA to create a... Surface M (See point 3 below for description), such as Figure 12 As shown, the so-called scan path is based on... GStarting from vertex A and ending at vertex A, by continuously cutting the wind turbine with several planes perpendicular to the wind turbine's rotation axis L, we can obtain the corresponding different blade cross sections and blade profiles.

[0051] 3: In the normal plane of the scanning path GA (the normal plane is perpendicular to the rotor rotation axis L), with the end point of the blade profile as the origin of the coordinate system, and the tangent direction of the end point of the blade profile as the positive X-axis, see as follows. Figure 13 As shown, Figure 13 It is on the normal plane of the starting point G of the scan path. Figure 13 Point G is the origin of the coordinate system, as described above. Surface M Its characteristics are: its cross-sectional shape on the normal plane of the scan path GA is a line segment of arbitrary length; one endpoint of the line segment is at the origin, and the angle between the line segment and the positive X-axis is f. Figure 13 On the normal plane of the starting point G of the scanning path, a line segment GY is obtained. The angle between line segment GY and the positive X-axis is f. In actual implementation, the value of f varies depending on the size of the wind turbine, and usually ranges from 3 to 10 degrees.

[0052] 4: with Surface M Taking the starting side where point G is located as the axis (i.e., with line segment GY as the axis of rotation), rotate by an angle i degrees towards the center of the wind turbine axis L, as follows: Figure 15 As shown, extending the curved surface M to intersect with blade 100 yields the crease line GH, with point H on blade profile line a. Figure 16 As shown, in actual implementation, the value of i varies depending on the size of the wind turbine, and usually ranges from 3 to 6 degrees.

[0053] 5: For example Figure 16 As shown, the AGH region (i.e., the corner bend 101) near the blade tip at the blade exit edge is folded toward the curved surface M and completely overlaps with the curved surface M. The resulting blade shape is the solution of this patent.

[0054] The essence of this invention is that the blade exit angle in the bending region is reduced by f degrees; and on curve GA, the bending length of the blade profile varies at different points. This is because the blade deformation is large at curve GA, resulting in a greater increase in blade work capacity. In practice, it has been found that the deformation is greater closer to point A, therefore, the bending length of the blade profile is longer closer to point A. Specifically, this is manifested in... Figure 17 As shown, the crease line GH and the exit edge 2 intersect with several blade profile lines. Each blade profile line intersects with the crease line GH and the exit edge 2 to form a curve VO. The length of the curve VO gradually increases from point G to vertex A. Of course, the length of the curve VO is zero at point G.

[0055] I. The manufacturing method of the sheet metal centrifugal impeller of the present invention can stabilize the blade structure and suppress the springback effect caused by the release of material stress, thereby reducing the deviation between the actual blade profile and the designed blade profile in the produced product.

[0056] Second, by modifying the blade profile starting point parameters and reducing the blade exit angle through the manufacturing method of the sheet metal centrifugal impeller of this invention, it is possible to ensure that the airflow angle at the blade exit after rebound conforms to the original design, thereby reducing the amplitude of the impeller exceeding the original design range and preventing the input and output power of the motor connected to the impeller from increasing beyond the motor's allowable limits. This, in turn, avoids a series of deteriorating problems such as excessive motor temperature rise, decreased motor output efficiency, and accelerated failure of motor components.

[0057] 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.

[0058] Example 2:

[0059] A sheet metal centrifugal impeller, characterized in that it is manufactured using the sheet metal centrifugal impeller manufacturing method described in Example 1.

[0060] 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 each blade (100) comprises an inlet edge (1), an outlet edge (2), a blade root (3), and a blade tip (4), characterized in that: A curve AG is formed on the exit edge (2) from vertex A to point G. A curve AH is formed on the blade tip (4) from vertex A to point H. A crease line (102) is formed on the blade (100) by connecting point H and point G. Curves AG, curve AH and crease line GH form an angular bend (101) on the blade (100). The angular bend (101) bends toward the center of the wind turbine rotation axis L. The crease line (102) mentioned above is formed as follows: S1) Starting from point G and ending at vertex A, sweep the path GA along the exit edge (2) and draw the surface M. On each normal plane of the sweep path GA, take the end point of the blade profile as the origin of the coordinate system, and the tangent direction of the end point of the blade profile as the positive X-axis. Surface M Its characteristics are: its cross-sectional shape on each normal plane of the scanning path GA is a line segment; one end of the line segment is at the origin of the coordinate system, and the angle between the line segment and the positive direction of the X-axis is f; S2) with Surface M If the starting edge GY where point G is located is the axis, and the surface M is rotated by an angle i towards the center of the wind turbine axis L, then the surface M is extended to intersect with the blade, and the crease line GH can be obtained.

2. The manufacturing method of a sheet metal centrifugal impeller according to claim 1, characterized in that: The length of the above curve AG is less than or equal to 1 / 2 the length of the exit edge (2).

3. The manufacturing method of a sheet metal centrifugal impeller according to claim 1, characterized in that: The value of f ranges from 3 to 10 degrees.

4. The manufacturing method of a sheet metal centrifugal impeller according to claim 3, characterized in that: The angle i ranges from 3 to 6 degrees.

5. The method for manufacturing a sheet metal centrifugal impeller according to claim 4, characterized in that: The corner bend (101) bends toward the center of the wind turbine rotation axis L, meaning that the corner bend (101) bends toward the curved surface M and completely coincides with the curved surface M.

6. A method for manufacturing a sheet metal centrifugal impeller according to any one of claims 1 to 5, characterized in that: The crease line GH and the exit edge (2) intersect with several blade profiles. Each blade profile intersects with the crease line GH and the exit edge (2) to form a curve VO. The length of the curve VO gradually increases from point G to vertex A.

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