A steam turbine blade root weight-reducing structure, a steam turbine blade, and a manufacturing method thereof

Abstract

The application discloses a steam turbine moving blade root weight-reducing structure, a steam turbine moving blade and a manufacturing method thereof. The steam turbine moving blade root weight-reducing structure comprises a fir-type blade root and a blade root intermediate body connecting a blade body and the fir-type blade root, and a weight-reducing groove is arranged on the inner arc side of the blade root intermediate body. The opening area of the weight-reducing groove accounts for 60%-40% of the area of the inner arc side without the weight-reducing groove. After the assembly of adjacent blades is completed, the contact area of the inner arc side of the blade root intermediate body accounts for 40%-60% of the contact area of the inner arc side of the blade root intermediate body without the weight-reducing groove. The application has the advantages that the average stress level of the blade root area can be effectively reduced, the manufacturing cost of the blade is reduced, the processing difficulty of the blade is not increased, the blade root weight can be reduced, the strength and rigidity of the blade root can be effectively ensured, and the like.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine technology, specifically a steam turbine blade root weight reduction structure, a steam turbine blade, and its manufacturing method. Background Technology

[0002] In the field of steam turbine technology, blade design and structural optimization are crucial for improving unit stability.

[0003] The blade root is a crucial part connecting the blade and the rotor, and its strength and rigidity directly affect the safe operation of the blade. In traditional fir-type blade root designs, in order to ensure sufficient strength and rigidity, the weight of the blade root area is often relatively large. This not only increases material costs but also increases the inertial force of rotating parts, negatively impacting the stability of the unit.

[0004] Existing technological solutions: To address the aforementioned problems, several solutions already exist in the prior art. For example, the weight of the leaf root can be reduced by altering its shape and size, or by using different materials. However, these methods often affect the strength and stiffness of the leaf root, or increase manufacturing costs.

[0005] Although existing technologies have provided some solutions, some problems and limitations still exist.

[0006] First, existing solutions often fail to achieve significant weight reduction while ensuring the strength and stiffness of the blade root.

[0007] Secondly, existing solutions may increase manufacturing costs or make the blades more difficult to process.

[0008] Furthermore, existing solutions may negatively impact the strength performance of the blades, such as increasing the risk of blade vibration.

[0009] Therefore, how to achieve effective weight reduction while ensuring blade root strength and stiffness is an urgent problem to be solved in the field of turbine blade design. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by providing a turbine blade root weight reduction structure, a turbine blade, and a method for manufacturing the same, which effectively reduces the average stress level in the blade root region without increasing the processing difficulty of the blade, achieves blade root weight reduction, and effectively ensures blade root strength and stiffness.

[0011] The technical objective of this invention is achieved through the following technical solution: A turbine blade root weight reduction structure includes a fir-shaped blade root and a blade root intermediate body connecting the blade body and the fir-shaped blade root. A weight reduction groove is formed on the inner arc side of the blade root intermediate body. The opening area of ​​the weight reduction groove accounts for 60% to 40% of the area of ​​the inner arc side without the weight reduction groove. After adjacent blades are assembled, the contact area of ​​the inner arc side of the blade root intermediate body accounts for 40% to 60% of the contact area of ​​the inner arc side of the blade root intermediate body without the weight reduction groove.

[0012] Preferably, the weight-reducing groove is a U-shaped groove with an opening at the lower end, and the corners of the U-shaped groove are rounded.

[0013] Preferably, the length L of the U-shaped groove satisfies: 20mm ≤ L ≤ 30mm, the width W satisfies: 10mm ≤ W ≤ 15mm, and the depth H satisfies: 3mm ≤ H ≤ 5mm.

[0014] Preferably, the radius R of the U-shaped groove satisfies: 3mm ≤ R ≤ 5mm.

[0015] Preferably, the arc of the U-shaped groove transitions to the groove wall through a continuous smooth curved surface.

[0016] Preferably, the fir-shaped leaf roots have a structure of three to five pairs of teeth.

[0017] Preferably, the axis of symmetry of the weight-reducing groove coincides with the radial centerline of the blade.

[0018] A turbine blade includes a fir-shaped blade root and a blade root intermediate body connecting the blade body and the fir-shaped blade root; the inner arc side of the blade root intermediate body is provided with the aforementioned turbine blade blade root weight reduction structure.

[0019] A method for manufacturing the above-mentioned turbine blades includes the following steps: Step 1: Select low-density, high-tensile-strength alloy steel to make the fir-shaped leaf roots, leaf root intermediates, and leaf blades; Step 2: Machining a weight-reducing groove on the inner arc side of the blade root intermediate body, and dynamically adjusting the opening area of ​​the weight-reducing groove according to the dimensions of the blade root intermediate body to meet the following requirements: (Total surface area of ​​the inner arc side of the leaf root intermediate - opening area of ​​the weight reduction groove) / Total surface area of ​​the inner arc side of the leaf root intermediate × 100% = 40%~60%.

[0020] Preferably, after step three, the weight reduction groove is opened, the shape, size and distribution of the weight reduction groove are adjusted through simulation calculation and experimental verification to make the centrifugal force distribution of the blade more uniform during the rotation process.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1. The turbine blade root weight reduction structure of the present invention involves creating a weight reduction groove on the inner arc side of the blade root intermediate body. By setting the weight reduction groove on the inner arc side of the blade root intermediate body, the average stress level in the blade root region can be effectively reduced, thereby achieving weight reduction of the blade root. This structure not only reduces material costs but also reduces the inertial forces of rotating components. Unlike existing technologies that change the shape and size of the blade root or use different materials to reduce its weight, this structure achieves weight reduction without affecting the strength and stiffness of the blade root. This is because the weight reduction groove is located in the intermediate body of the blade root, where the strength and stiffness have a relatively small impact on the overall blade root. Compared to changing the shape and size of the blade root or using different materials to reduce its weight, this structure is easier to implement and does not increase the processing difficulty of the blade. Therefore, the present invention has the advantages of effectively reducing the average stress level in the blade root region, reducing blade manufacturing costs, not increasing blade processing difficulty, achieving blade root weight reduction, and effectively ensuring blade root strength and stiffness.

[0022] 2. In the specific implementation of the turbine blade root weight reduction structure manufactured by this invention, the axis of symmetry of the weight reduction grooves coincides with the radial centerline of the blade. This technical measure ensures that the arrangement of the weight reduction grooves matches the direction of force on the blade. During blade rotation, centrifugal force mainly acts radially. The symmetrical design allows for a more uniform stress distribution on the weight-reduced blade after being subjected to force, avoiding problems such as excessive local stress or uneven deformation caused by the offset of the weight reduction grooves. This ensures balanced strength and stiffness of the blade in all directions, maintaining the stability and reliability of turbine operation and reducing the risk of vibration and imbalance.

[0023] 3. The turbine blade of the present invention incorporates a blade root weight reduction structure on the inner arc side of the blade root intermediate body. This effectively reduces weight while maintaining blade root strength and rigidity, which is significant for improving turbine stability. Furthermore, it reduces blade manufacturing costs and the inertial forces of rotating components, thus contributing to reduced energy consumption and extended equipment lifespan.

[0024] In addition, it can improve the dynamic performance of the blades and reduce the risk of blade root cracks, which is of great value for improving the operational safety of the equipment.

[0025] 4. The turbine blade manufactured by the method of the present invention can effectively reduce the weight of the blade while ensuring the strength, stiffness and dynamic performance of the blade, reducing the manufacturing cost of the blade, improving the dynamic performance of the blade, reducing the risk of blade root cracks, and improving the operational safety of the equipment. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 The front view; Figure 3 yes Figure 2 Side view; Figure labels: 1—Fir-shaped leaf root; 2—Leaf root intermediate body; 21—Inner arc side; 3—Leaf body; 4—Weight reduction groove. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Example 1 like Figure 1 — Figure 3As shown, a turbine blade root weight reduction structure includes a fir-shaped blade root 1 and a blade root intermediate body 2 connecting the blade body 3 and the fir-shaped blade root 1. A weight reduction groove 4 is formed on the inner arc side 21 of the blade root intermediate body 2. The opening area of ​​the weight reduction groove 4 accounts for 60% to 40% of the area of ​​the inner arc side 21 of the blade root intermediate body 2 without the weight reduction groove 4. After adjacent blades are assembled, the contact area of ​​the inner arc side 21 of the blade root intermediate body 2 accounts for 40% to 60% of the contact area of ​​the inner arc side 21 of the blade root intermediate body 2 without the weight reduction groove 4. By setting the weight reduction groove 4 on the inner arc side 21 of the blade root intermediate body 2, the average stress level in the blade root region can be effectively reduced, thereby achieving weight reduction of the blade root. This structure not only reduces material costs but also reduces the inertial force of rotating parts. Unlike existing technologies that change the shape and size of the blade root or use different materials to reduce the weight of the blade root, this structure achieves weight reduction without affecting the strength and stiffness of the blade root. This is because the weight-reducing groove 4 is located in the middle part 2 of the blade root, where the strength and stiffness have a relatively small impact on the overall blade root. Compared to changing the shape and size of the blade root, or using different materials to reduce its weight, this structural approach is easier to implement and does not increase the processing difficulty of the blade. Therefore, this technique effectively reduces the average stress level in the blade root region, lowers the manufacturing cost of the blade, does not increase the processing difficulty of the blade, achieves weight reduction of the blade root, and effectively ensures the strength and stiffness of the blade root.

[0031] like Figure 1 — Figure 3 As shown, the blade includes a fir-shaped leaf root 1 and a leaf root intermediate body 2 connecting the blade body 3 and the fir-shaped leaf root 1. A weight-reducing groove 4 is formed on the inner arc side 21 of the leaf root intermediate body 2. The opening area of ​​the weight-reducing groove 4 accounts for 60% to 40% of the area of ​​the inner arc side 21 without the weight-reducing groove 4; that is, the opening area of ​​the weight-reducing groove 4 = the area of ​​the inner arc side 21 of the leaf root intermediate body 2 without the weight-reducing groove 4 × (60% to 40%). After adjacent blades are assembled, the contact area of ​​the inner arc side 21 of the leaf root intermediate body 2 accounts for 40% to 60% of the contact area of ​​the inner arc side 21 of the leaf root intermediate body 2 without the weight-reducing groove 4. This technical measure achieves weight reduction by decreasing the contact area, reducing the average stress in the wheel groove, reducing stress concentration, and improving the overall fatigue life of the blade; it also avoids insufficient blade connection stiffness due to an excessively small contact area, which would affect the turbine's operational stability and reliability, thus achieving a balanced optimization of weight reduction and blade performance. like Figure 1 — Figure 3As shown, the fir-shaped blade root 1 has a three- to five-pair tooth structure. This technique ensures that the fir-shaped blade root 1 possesses excellent connection strength and rigidity. Combined with the weight-reducing groove 4, while achieving weight reduction at the blade root, it also guarantees a reliable connection between the blade and the rim, ensuring that the blade can withstand complex loads such as centrifugal force generated by high-speed rotation and steam forces. This maintains the dynamic balance and stable operation of the turbine rotor, providing strong support for the overall performance of the turbine.

[0032] In practice, the axis of symmetry of the weight-reducing groove 4 coincides with the radial centerline of the blade. This technique ensures that the arrangement of the weight-reducing groove 4 matches the direction of force on the blade. During blade rotation, centrifugal force primarily acts radially. The symmetrical design allows for a more uniform stress distribution on the weight-reduced blade after being subjected to force, avoiding problems such as excessive local stress or uneven deformation caused by the offset of the weight-reducing groove 4. This ensures balanced strength and stiffness of the blade in all directions, maintains the smoothness and reliability of turbine operation, and reduces the risk of vibration and imbalance.

[0033] In practical implementation, the weight-reducing groove 4 is a U-shaped groove with an open bottom and rounded corners. By designing the weight-reducing groove 4 as a U-shaped groove with rounded corners, compared to other shapes (such as sharp corners), the rounded transition effectively reduces the stress concentration factor around the weight-reducing groove 4, preventing crack initiation and propagation caused by stress concentration. This enhances the fatigue resistance of the blade under high-frequency vibration and complex stress environments, improving the blade's reliability and service life. In practical implementation, if the U-shaped groove were open at the top, stress would concentrate in the blade root area. The open bottom design avoids stress concentration in the blade root area. The relatively regular shape of the U-shaped groove makes it easy to use existing machining processes (such as milling) for precise machining, ensuring the dimensional accuracy and surface quality of the weight-reducing groove 4. It also facilitates quality inspection and control, reducing manufacturing difficulty and cost. At the same time, the unidirectional open structure of the U-shaped groove allows for one-time forming using a standard tapered milling cutter, reducing multiple finishing processes compared to a closed groove, effectively reducing machining time and tool wear.

[0034] Therefore, this structure effectively reduces the average stress level in the blade root region, has low processing costs, and effectively reduces manufacturing difficulty.

[0035] In practical implementation, the arc of the U-shaped groove transitions to the groove wall through a continuous, smooth curved surface. This structure avoids stress concentration caused by abrupt changes in cross-section, allowing stress to gradually change and disperse along the smooth curved surface. This further reduces the risk of fatigue crack initiation during blade operation, improving blade reliability and service life.

[0036] In this embodiment, the length L of the U-shaped groove satisfies: 20mm ≤ L ≤ 30mm, the width W satisfies: 10mm ≤ W ≤ 15mm, and the depth H satisfies: 3mm ≤ H ≤ 5mm.

[0037] Preferably, the length L of the U-shaped groove is 26 mm, the width W is 12.8 mm, and the depth H is 4 mm. Within this size range, it is possible to ensure that the weight-reduction groove 4 removes enough material to meet the weight reduction requirements, reduce the weight of the blade, and reduce centrifugal force and wheel groove stress; at the same time, it is possible to ensure the structural integrity of the remaining part of the blade, meet the strength and stiffness requirements, and avoid problems such as deformation and cracking of the blade under complex conditions such as high-speed rotation and high temperature and pressure due to excessive weight reduction, thus ensuring the safe and stable operation of the steam turbine.

[0038] In practical implementation, the radius R of the U-shaped groove must satisfy: 3mm ≤ R ≤ 5mm.

[0039] Preferably, the radius R of the arc is 4 mm. A suitable radius of arc helps to better distribute stress, reduce local stress peaks, reduce the risk of stress concentration, improve the fatigue resistance and overall mechanical properties of the blade, and ensure that the blade has good reliability and durability in long-term operation while ensuring weight reduction.

[0040] Example 2 A turbine blade includes a fir-shaped blade root 1 and a blade root intermediate body 2 connecting the blade body 3 and the fir-shaped blade root 1; the inner arc side 21 of the blade root intermediate body 2 is provided with the turbine blade root weight reduction structure of Embodiment 1.

[0041] In practical implementation, the turbine blade root weight reduction structure of Embodiment 1 is provided on the inner arc side 21 of the blade root intermediate body 2. This allows for effective weight reduction while maintaining blade root strength and stiffness, which is of great significance for improving turbine stability.

[0042] Secondly, it can reduce the manufacturing cost of blades and the inertial force of rotating parts, which has a positive effect on reducing energy consumption and increasing the service life of equipment.

[0043] In addition, it can improve the dynamic performance of the blades and reduce the risk of blade root cracks, which is of great value for improving the operational safety of the equipment.

[0044] A method for manufacturing the above-mentioned turbine blades includes the following steps: Step 1: Select low-density, high-tensile-strength alloy steel to make the fir-shaped leaf root 1, leaf root intermediate 2, and leaf body 3.

[0045] In practical implementation, 14NiCr18 alloy steel, with a density of 7.80 g / cm³ and a strength exceeding 1000 MPa, can be selected as the alloy steel material with low density and high tensile strength. The low density reduces blade weight and centrifugal force, while the high tensile strength ensures the blade has sufficient resistance to deformation and fracture under complex stresses. This method enables the weight-reduced blades to possess excellent comprehensive mechanical properties, meeting the operational requirements of steam turbines under harsh conditions such as high temperature, high pressure, and high speed.

[0046] Step 2: Machining a weight-reducing groove 4 on the inner arc side 21 of the blade root intermediate body 2, and dynamically adjusting the opening area of ​​the weight-reducing groove 4 according to the dimensions of the blade root intermediate body 2 to satisfy: (Total surface area of ​​inner arc side 21 of leaf root intermediate 2 - opening area of ​​weight reduction groove 4) / Total surface area of ​​inner arc side 21 of leaf root intermediate 2 × 100% = 40%~60%.

[0047] In practical implementation, the weight-reducing groove 4 is machined using multi-axis CNC milling, and the arc portion is formed using a ball end mill to ensure a continuous and smooth surface transition. The opening area of ​​the weight-reducing groove 4 is dynamically adjusted according to the dimensions of the blade root intermediate body 2 to meet the contact area ratio requirements. This design method can adapt to the manufacturing needs of blades of different specifications and sizes, ensuring that each blade can achieve maximum weight reduction while meeting strength and stiffness requirements, improving the versatility and adaptability of the production process, and reducing production costs.

[0048] Step 3: After the weight reduction groove 4 is set up, the shape, size and distribution of the weight reduction groove 4 are adjusted through simulation calculation and experimental verification to make the centrifugal force distribution of the blade more uniform during the rotation process.

[0049] In practical implementation, after the weight reduction groove 4 is opened, through simulation calculation and experimental verification, we can gain a deep understanding of the actual centrifugal force distribution of the blade during rotation. Based on the verification results, we can adjust the shape, size and distribution of the weight reduction groove 4 in a targeted manner to further optimize the uniformity of centrifugal force distribution of the blade, reduce the overall stress level in the blade root area, reduce vibration risk, improve the reliability and service life of the blade, and ensure that the performance of the blade after weight reduction reaches the best state to meet the requirements of safe and stable operation of the steam turbine.

[0050] Therefore, this method can effectively reduce the weight of the blades while ensuring their strength, stiffness, and dynamic performance, reducing manufacturing costs, improving dynamic performance, reducing the risk of blade root cracks, and enhancing equipment operational safety.

[0051] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A weight reduction structure for the blade root of a steam turbine blade, comprising a fir-shaped blade root and a blade root intermediate connecting the blade body and the fir-shaped blade root, characterized in that: A weight-reducing groove is provided on the inner arc side of the leaf root intermediate body; The opening area of ​​the weight-reducing groove accounts for 40% to 60% of the area of ​​the inner arc side without the weight-reducing groove; after adjacent blades are assembled, the contact area of ​​the inner arc side of the blade root intermediate body accounts for 40% to 60% of the contact area of ​​the inner arc side of the blade root intermediate body without the weight-reducing groove. The weight-reducing groove is a U-shaped groove with an opening at the bottom, and the corners of the U-shaped groove are rounded. The length L of the U-shaped groove satisfies: 20mm ≤ L ≤ 30mm, the width W satisfies: 10mm ≤ W ≤ 15mm, and the depth H satisfies: 3mm ≤ H ≤ 5mm; The arc of the U-shaped groove transitions to the groove wall through a continuous and smooth curved surface; The fir-type leaf roots have a structure of three to five pairs of teeth; The axis of symmetry of the weight reduction groove coincides with the radial centerline of the blade.

2. The turbine blade root weight reduction structure according to claim 1, characterized in that: The radius R of the arc of the U-shaped groove satisfies: 3mm ≤ R ≤ 5mm.

3. A turbine blade, characterized in that, It includes a fir-shaped leaf root and a leaf root intermediate body connecting the leaf body and the fir-shaped leaf root; the inner arc side of the leaf root intermediate body is provided with the turbine motor blade root weight reduction structure as described in any one of claims 1-2.

4. A method for manufacturing turbine blades as described in claim 3, characterized in that... This includes the following steps: Step 1: Select low-density, high-tensile-strength alloy steel to make the fir-shaped leaf roots, leaf root intermediates, and leaf blades; Step 2: Machining a weight-reducing groove on the inner arc side of the blade root intermediate body, and dynamically adjusting the opening area of ​​the weight-reducing groove according to the dimensions of the blade root intermediate body to meet the following requirements: (Total surface area of ​​the inner arc side of the leaf root intermediate - area of ​​the weight reduction groove opening) / Total surface area of ​​the inner arc side of the leaf root intermediate × 100% = 40%~60%.

5. The method for manufacturing turbine blades according to claim 4, characterized in that... The process also includes the following steps: Step 3: After the weight reduction tank is opened, the shape, size and distribution of the weight reduction tank are adjusted through simulation calculation and experimental verification to make the centrifugal force distribution of the blade more uniform during the rotation process.

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