High-precision turbine blade integral casting structure and root extension machining method

Abstract

The invention discloses a high-precision turbine blade integral casting structure and a root extension machining method.The high-precision turbine blade integral casting structure comprises a blade body part, a root extension part and a tenon tooth part, the blade body part, the root extension part and the tenon tooth part are integrally cast and formed, and the root extension part comprises a margin plate part and a damping table; the flange plate and the damping table adopt transition cambered surface design, the root extending part is arranged in a conical shape, grinding machining and electric spark machining technologies are sequentially adopted, the flange plate and the damping table are machined on the root extending part, and root extending part machining of the turbine blade casting structure is carried out. According to the method, the blade casting structure is changed to be matched with the electromachining technology, the problem of mixed crystal casting of the root extension section of the single-crystal turbine blade is fundamentally solved, the size precision of the root extension section of the turbine blade is improved, the mass dispersion degree of the weight, frequency and fatigue strength of the turbine rotor blade is improved, and the size precision in a turbine rotor assembly can be improved.

Description

Technical Field

[0001] This invention relates to the field of aerospace component structural design technology, and in particular to a high-precision integral casting structure for turbine blades and a root extension machining method. Background Technology

[0002] Aero engines are characterized by high thrust-to-weight ratio, large thrust, and high reliability. Their development integrates top technologies from multiple disciplines such as flow, heat transfer, structure, materials, control, and mechanics. Currently, the turbine inlet gas temperature of advanced aero engines can reach 1800-2000K, which is enough to turn the world's most heat-resistant alloys into molten steel. Turbine blades must work reliably at this temperature for a long time, which makes their development extremely difficult. The turbine blade root, as the transition section between the blade body and the tenon, includes a structurally protruding edge plate and a damping platform. The structural shape changes drastically. This is to achieve functions such as flow channel sealing and damping, which is a conventional design. The turbine blade root section is subjected to the combined effects of centrifugal force, aerodynamic force, thermal stress and vibration stress. The stress amplitudes are huge and the coupling modes are varied. Therefore, the structural design and manufacturing problems of the turbine blade root section are very difficult to handle.

[0003] Because the blade root extension section edge plate and damping structure are a structural abrupt change relative to the blade body and tenon, defects such as impurities, small-angle grain boundaries and recrystallization are easily generated in this area during single crystal casting. This is one of the important reasons for the scrapping of the second-generation single crystal blades. For the more advanced third and fourth generation single crystals, the problem is even more prominent due to the increased content of refractory elements such as rhenium and the decline in alloy casting performance. Negative deviations in the blade root region reduce the effective load-bearing area and increase the risk of blade breakage at the root; positive deviations increase blade weight, increase turbine disk load, and increase the risk of turbine disk tenon fracture. Whether it's blade root fracture or turbine disk tenon fracture, due to the large mass and high kinetic energy of the detached fragments, they are prone to penetrating the casing, leading to non-containment failures and endangering aircraft flight safety—both are extremely high-risk failure modes. It can be said that the structural dimensions of the turbine blade root section are limited to both sides, making out-of-tolerance handling extremely difficult. If the dimensions of the turbine disk, turbine blades, and other related components are increased during structural design to ensure sufficient strength reserves, it will increase the weight of turbine components, reduce the overall thrust-to-weight ratio, and decrease the advanced nature of the aero-engine. Furthermore, the large range of variations in the structural dimensions of the turbine blade root section also increases the dispersion of blade weight, frequency, and fatigue life, increasing operational risks.

[0004] Currently, turbine disks are machined, achieving a tolerance of 0.02 mm; however, turbine blade root extension sections are precision cast without allowance, with a dimensional tolerance of only 0.2–0.3 mm, representing a difference in precision by an order of magnitude. Therefore, improving the overall precision of turbine component disk assemblies is primarily limited by the turbine blades. Further improving the dimensional machining accuracy of the blade root extension sections is a key requirement for the design and development of advanced aero-engine turbine blades.

[0005] In summary, turbine blades are core components of aero-engines, and their temperature resistance directly determines the overall performance of the engine. To meet the requirements of ultra-high temperature operating environments, turbine blades employ complex cooling structures within their internal cavities, and the matrix utilizes ultra-high temperature alloys and single-crystal materials. This limits the production of turbine blades to zero-margin precision casting. With the upgrading of single-crystal materials, alloy costs have increased, and casting processability has declined, leading to increasingly prominent casting defects in the root extension section edge plates and damping platforms of advanced single-crystal turbine blades. Furthermore, the casting dimensional accuracy of the blade root extension section is only 0.2–0.3 mm, significantly lower than the 0.02 mm accuracy of other turbine components such as discs and shafts, becoming a bottleneck for improving the overall dimensional accuracy of advanced aero-engine turbine disc assemblies. Therefore, we propose a high-precision integral casting structure for turbine blades and a root extension machining method. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-precision integral casting structure for turbine blades and a root extension machining method. By changing the structure of the blade casting, this invention fundamentally solves the problem of impurities in the casting of the root extension section of single-crystal turbine blades, improves the dimensional accuracy of the root extension section of turbine blades, and not only improves the mass dispersion of turbine rotor blade weight, frequency and fatigue strength, but also improves the dimensional accuracy bottleneck in turbine rotor assemblies.

[0007] The objective of this invention is achieved as follows: a high-precision turbine blade casting, comprising a blade body, an extension root, and a tenon tooth, wherein the blade body, extension root, and tenon tooth are integrally cast, the extension root comprises a rim plate and a damping platform, the damping platform connecting the rim plate and the tenon tooth, the rim plate and the damping platform adopting a transition arc surface design, and the extension root being tapered.

[0008] A method for manufacturing a high-precision turbine blade, comprising the following steps: S1, Casting structure setting: The turbine blade is designed as an integral cast structure, with the lower edge of the flange plate and the damping platform set as the root extension part, specifically an integral conical structure; S2, Directional solidification casting: Using single-crystal directional solidification process, a blade casting with the integral conical root extension section is cast; S3, Machining and Forming: The tenons are machined using grinding, and the flange and damping platform structure are machined on the root extension section using electrical discharge machining.

[0009] Optionally, the volume of the conical structure completely encompasses the original lower edge plate and damping boss structure, and dimensional allowances are provided in each direction.

[0010] Optionally, the specific process of step S2 is as follows: S21, Prepare blade wax mold based on blade design model; S22, a blade wax mold is formed by pressure injection using a wax injection device, and the sprue, crystal selector, blade, etc. are bonded together to form a blade casting wax mold; S23, prepare a ceramic shell on the surface of the wax mold, heat to dewax and calcine the ceramic shell at high temperature; S24 uses directional solidification equipment to heat the blade mold shell, melts the single crystal high-temperature alloy into molten metal, and then pours it into the ceramic mold shell. S25 uses a directional pulling mechanism and a heat insulation device to move the ceramic shell from the high temperature zone to the low temperature zone, forming a high temperature gradient along the blade axis. S26, the single-crystal blade solidifies, crystallizes and grows under the axial temperature gradient. After competing to grow into a single grain through the crystal selector at the bottom of the blade, it continues to solidify into a single-crystal blade inside the ceramic shell of the blade.

[0011] Optionally, the blade root extension section of the blade wax mold is provided as a conical cavity, which completely encloses the original lower edge plate and damping boss structure.

[0012] Optionally, the specific process of step S3 is as follows: S31, calibrate the reference surface, use a six-point positioning fixture to clamp the blade body, set the grinding tool and compile the grinding program based on the tenon parameters; S32, set the grinding parameters and perform the grinding process; S33, coordinate measuring machine for tenon size detection; S34, clamp the blade casting with the tenon teeth machined, and set the electrode based on the final blade structure; S35, sets multi-stage discharge parameters for layered processing; S36, online detection of machining dimensions, and reprocessing of out-of-tolerance areas.

[0013] Optionally, the layered processing includes (parameters may vary depending on the blade material): Roughing stage: peak current 8-15A, pulse width 300±30ti, layered removal of excess material; Finishing stage: peak current 6~10A, pulse width 260±20ti, forming edge plate and root extension structure; Micro-finishing stage: peak current 6-8A, pulse width 200±15ti, polishing the machined surface.

[0014] Optionally, during the finishing stage, the electrode feed path is dynamically adjusted by monitoring the electrode wear in real time and using dual feedback of optical measurement and discharge pulse counting.

[0015] Optionally, during the layered processing, a multi-angle nozzle array is used to apply electrical discharge machining fluid. The fluid is pressure-sprayed after two-stage filtration, and a temperature sensor is installed in the processing area for closed-loop temperature control.

[0016] Optionally, the optical measurement and discharge pulse counting specifically include: Optical measurements are performed by scanning the electrode morphology using a laser displacement sensor, with a measurement accuracy of ≤2μm. Discharge pulse counting is performed by statistically analyzing effective discharge pulses and combining them with a material removal model to calculate cumulative loss. When the electrode single-sided loss is detected to be ≥10μm, a three-dimensional compensation map is generated and the CNC axis feed path is adjusted with a compensation step size ≤5μm. At the same time, based on the abnormal loss rate, the peak current is reduced or the pulse interval is extended. After processing 0.05mm of depth, the feed is paused for optical calibration, and the loss is output after processing is completed.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention fundamentally solves the problem of impurities in the casting root section of single-crystal turbine blades by changing the structure of the blade casting, thereby improving the casting yield of single-crystal blades. By adopting a cone-shaped body that completely encloses the original structure, combined with a directional solidification process with axial gradient heating, the complete growth of high rhenium single crystals is ensured, thereby improving the casting yield. The multi-stage electrical discharge machining process achieves precision forming of complex structures through intelligent electrode loss compensation, multi-angle high-pressure flushing, and a closed-loop temperature control system, ensuring machining accuracy and surface roughness, and solving the problems of difficult machining of high-hardness single-crystal materials and low forming accuracy of complex structures. Compared with traditional processes, this invention improves the dimensional accuracy of the turbine blade root extension section, significantly reduces the mass dispersion of turbine rotor blade weight, frequency and fatigue strength, and improves the dimensional accuracy bottleneck in turbine rotor assemblies. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the original turbine blade.

[0020] Figure 2 This is a schematic diagram of the turbine blade casting structure provided by the present invention.

[0021] Figure 3 This is a schematic diagram of the development of blade cooling structures.

[0022] Figure 4 This is a schematic diagram of a common blade root extension section edge plate damping structure.

[0023] Figure 5This is a schematic diagram of the directional solidification casting process provided by the present invention.

[0024] Figure 6 This is a schematic diagram of the electrical discharge machining process provided by the present invention.

[0025] In the diagram: 1. Leaf blade; 2. Root extension; 3. Leaf blade; 4. Marginal plate; 5. Damping platform. Detailed Implementation

[0026] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that in the common structure of turbine blades, an important means to improve the temperature resistance of turbine blades is to make the inside of the turbine blades hollow and use internal cooling air to reduce the blade wall temperature. This method has achieved remarkable results in engineering applications and has been widely adopted in the industry.

[0028] Currently, turbine blade internal cavity cooling has evolved from simple convection cooling to convection combined with film cooling, and then to enhanced convection combined with impingement combined with film cooling, such as... Figure 3 As shown, even the latest double-wall cooling systems exist. The complex internal structure limits the manufacturing methods of turbine blades, and the extremely high hardness of the blade material makes ordinary machining very difficult. Therefore, turbine blades are currently generally produced using a zero-margin precision casting process.

[0029] To improve the temperature resistance of turbine blades, the materials used have evolved from early wrought high-temperature alloys to cast alloys, directionally solidified alloys, and single crystals. Advanced aero-engine turbine blades are mostly made using single-crystal casting, where the entire blade is formed from a single grain. During casting and machining, it is crucial to prevent the formation of impurities and recrystallization. Because grain boundary strengthening elements are eliminated in the alloy, grain boundaries are removed, effectively improving the material's temperature resistance and load-bearing capacity, leading to its widespread adoption in advanced aero-engines. Currently, four generations of single-crystal alloys have been developed. With each generation increasing the rhenium content, the temperature resistance of single-crystal alloys gradually improves. However, the material price has also increased significantly. Even the second-generation single-crystal alloys, which are widely used in engineering, cost several million yuan per ton, about 10 times the price of ordinary high-temperature alloys. Simultaneously, the reduced processability of high-rhenium single-crystal casting further lowers the casting yield, causing the production cost of more advanced third-generation single-crystal blades to skyrocket, with prices approaching those of gold of the same weight.

[0030] like Figures 1 to 2The high-precision turbine blade casting shown includes a blade body 1, an extension root 2, and a tenon tooth 3. The blade body 1, the extension root 2, and the tenon tooth 3 are integrally cast. The extension root 2 includes a rim plate 4 and a damping platform 5. The damping platform 5 connects the rim plate 5 and the tenon tooth 3. The rim plate 4 and the damping platform 5 adopt a transition arc surface design. The extension root 2 is tapered.

[0031] Furthermore, the blade casting structure was modified according to casting requirements. The complex flange and damping platform structure at the root of the turbine blade was transformed into a simple cone. At the same time, the cone was required to completely enclose the flange and damping platform structure in terms of volume. The modified blade casting structure can improve the abrupt shape of the flange and damping platform structure, fundamentally eliminate the causes of casting defects in the flange and damping platform of the root section of single-crystal blades, reduce the casting difficulty of high rhenium single-crystal blades, improve the yield of single-crystal blade castings, and reduce manufacturing costs. First, the complex edge plate and damping platform structure of the turbine blade root extension section is modified into a simple cone. By optimizing the single crystal growth conditions through geometric continuity, the cone completely encloses the final structure, which can eliminate the solidification interface disorder caused by the abrupt change in cross section in the traditional scheme, and enable dendrites to grow stably along the axial direction. This fundamentally avoids the impurity crystal defects caused by uneven heat flow distribution and solute segregation, and has a significant improvement on the casting process of high rhenium single crystal alloys. Secondly, by reconstructing the stress and temperature field distribution through smooth transition geometric features, the truncated conical structure combined with the large curvature transition arc surface can reduce the stress concentration effect and maintain a uniform solidification front advance speed, which not only improves the integrity of single crystals but also broadens the process parameter window and enhances the controllability of the casting process. Finally, the simplified casting structure can reduce the difficulty and cost of subsequent precision machining. The conical shape, as a reference geometric feature, not only reduces the difficulty of the casting process, but also provides an ideal allowance distribution for the electrical discharge machining process.

[0032] A method for manufacturing high-precision turbine blades includes the following steps: S1, Casting structure setting: The turbine blade is designed as an integral cast structure, with the lower edge of the flange plate and the damping platform set as the root extension part, specifically an integral conical structure; S2, Directional solidification casting: Using single-crystal directional solidification process, a blade casting with the integral conical root extension section is cast; S3, Machining and Forming: The tenons are machined using grinding, and the flange and damping platform structure are machined on the root extension section using electrical discharge machining.

[0033] Furthermore, the method provided by this invention first simplifies the complex edge plate and damping platform structure of the root extension section into an integral conical body for casting, so that the single crystal growth interface remains continuous and smooth, avoiding dendritic disorder and impurity defects caused by abrupt changes in cross section in the traditional scheme, and improving the casting qualification rate of high rhenium single crystal alloy. During the directional solidification stage, the conical structure can optimize the temperature and stress field distribution, ensuring stable growth of single crystals along the axial direction, and is particularly suitable for the preparation of rhenium-containing single crystals of the third generation and above. First, the tenons are ground by machining, and then the final structure is precisely formed on the cone by electrical discharge machining. Through multi-level discharge parameters and adaptive electrode compensation technology, the machining difficulties of high-hardness materials can be overcome, and the dimensional accuracy and surface quality of the edging plate and damping platform can be guaranteed.

[0034] Specifically, the process of step S2 is as follows: S21, Prepare blade wax mold based on blade design model; S22, a blade wax mold is formed by pressure injection using a wax injection device, and the sprue, crystal selector, blade, etc. are bonded together to form a blade casting wax mold; S23, prepare a ceramic shell on the surface of the wax mold, heat to dewax and calcine the ceramic shell at high temperature; S24 uses directional solidification equipment to heat the blade mold shell, melts the single crystal high-temperature alloy into molten metal, and then pours it into the ceramic mold shell. S25 uses a directional pulling mechanism and a heat insulation device to move the ceramic shell from the high temperature zone to the low temperature zone, forming a high temperature gradient along the blade axis. S26, the single-crystal blade solidifies, crystallizes and grows under the axial temperature gradient. After competing to grow into a single grain through the crystal selector at the bottom of the blade, it continues to solidify into a single-crystal blade inside the ceramic shell of the blade.

[0035] Specifically, the blade root extension section of the blade wax mold is set in a conical cavity, which completely encloses the original lower edge plate and damping boss structure.

[0036] Furthermore, in the process of this application, precision wax molding technology is first used to ensure the accurate forming of the complex aerodynamic profile and internal cooling structure of the blade. Then, a ceramic shell preparation process is used to provide a stable forming environment for subsequent high-temperature alloy casting. In the directional solidification stage, by precisely controlling the temperature gradient and solidification rate, the molten alloy is promoted to form a highly oriented single crystal structure, which fundamentally eliminates the grain boundary defect problem of traditional polycrystalline materials. Furthermore, the unique crystal growth method forms a highly oriented single crystal structure through directional solidification technology, fundamentally eliminating the grain boundary weaknesses of traditional polycrystalline materials and improving the high-temperature strength and creep resistance of the blades. This growth method optimizes the uniformity of the microstructure, which can effectively reduce component segregation and residual stress, while reducing defects such as porosity, shrinkage cavities and inclusions commonly encountered in the casting process. Thanks to the density and uniformity of the single crystal structure, the blades exhibit excellent oxidation resistance, thermal fatigue resistance and long-term durability under high temperature and high pressure environments, making them a core technology for high-performance blades in modern aero engines and gas turbines.

[0037] Specifically, the process of step S3 is as follows: S31, calibrate the reference surface, use a six-point positioning fixture to clamp the blade body, set the grinding tool and compile the grinding program based on the tenon parameters; S32, set the grinding parameters and perform the grinding process; S33, coordinate measuring machine for tenon size detection; S34, clamp the blade casting with the tenon teeth machined, and set the electrode based on the final blade structure; S35, sets multi-stage discharge parameters for layered processing; S36, online detection of machining dimensions, and reprocessing of out-of-tolerance areas.

[0038] Specifically, layered processing includes: Roughing stage: peak current 8-15A, pulse width 300±30ti, layered removal of excess material; Finishing stage: peak current 6~10A, pulse width 260±20ti, forming edge plate and root extension structure; Micro-finishing stage: peak current 6-8A, pulse width 200±15ti, polishing the machined surface.

[0039] It should be noted that the above data parameters were obtained through experiments, and the experimental data for the roughing stage parameters are shown in Table 1: Table 1. Experimental data of parameters in the roughing stage

[0040] In the roughing stage, the relationship between parameter balancing material removal efficiency and processing quality is maintained, ensuring high processing efficiency while controlling electrode wear and heat-affected layer depth, laying the foundation for subsequent precision processing. The experimental data of parameters during the finishing stage are shown in Table 2: Table 2. Parameters for the finishing stage

[0041] The parameters in the finishing stage take into account the forming requirements of the complex structure of turbine blades. While ensuring forming accuracy, they are also suitable for machining precision structures such as flanges and damping platforms, thereby improving the overall performance of the blades. This not only ensures the dimensional accuracy and surface integrity of key parts, but also effectively reduces stress concentration and the risk of microcracks, enabling the blades to have better aerodynamic efficiency, vibration damping characteristics and fatigue life under high temperature and high pressure conditions.

[0042] The experimental data for testing the surface quality of micro-finished products are shown in Table 3: Table 3. Surface Quality Testing for Micro-finished Machined Products

[0043] Micro-machining parameters are used to ensure surface integrity, not only meeting aerospace surface quality requirements, but also controlling the recast layer thickness to a minimum, so that the machined surface forms a beneficial compressive stress state, improving the fatigue resistance and service life of the blades.

[0044] Compared with traditional processing methods, the present invention significantly improves processing efficiency, ensures dimensional accuracy and surface quality, and reduces production costs.

[0045] Furthermore, this invention employs a multi-stage discharge parameter layered processing strategy. First, the excess material of the tapered root section is efficiently removed in the roughing stage. Then, the edge plate and damping platform structure are precisely formed in the finishing stage. Finally, the surface is polished in the micro-finishing stage. This progressive processing method can improve processing efficiency and ensure final dimensional accuracy and surface quality. Secondly, the online detection and reprocessing mechanism can control processing errors, which is particularly effective for the high hardness characteristics of high rhenium single crystal materials. By precisely matching the current parameters through electrical discharge machining technology, defects such as surface microcracks can be avoided. 。

[0046] Specifically, during the finishing stage, the electrode wear is monitored in real time, and the electrode feed path is dynamically adjusted by using dual feedback of optical measurement and discharge pulse counting. During the layered processing, a multi-angle nozzle array is used to flush with deionized water. The flushing solution is pressure-sprayed after two-stage filtration, and a temperature sensor is set in the processing area for closed-loop temperature control.

[0047] Furthermore, firstly, a dual feedback mechanism of optical measurement and discharge pulse counting is adopted to achieve real-time compensation for electrode wear, ensuring that the machining trajectory accuracy is controlled at the micron level; secondly, a multi-angle high-pressure flushing system combined with two-stage filtration can remove machining debris and maintain a stable discharge environment; in addition, closed-loop temperature control can avoid material deterioration caused by local overheating.

[0048] Specifically, optical measurement and discharge pulse counting are as follows: Optical measurements are performed by scanning the electrode morphology using a laser displacement sensor, with a measurement accuracy of ≤2μm. Discharge pulse counting is performed by statistically analyzing effective discharge pulses and combining them with a material removal model to calculate cumulative loss. When the electrode single-sided loss is detected to be ≥10μm, a three-dimensional compensation map is generated and the CNC axis feed path is adjusted with a compensation step size ≤5μm. At the same time, based on the abnormal loss rate, the peak current is reduced or the pulse interval is extended. After processing 0.05mm of depth, the feed is paused for optical calibration, and the loss is output after processing is completed.

[0049] Furthermore, in optical measurement, a high-precision laser displacement sensor is used to scan the working surface of the electrode, with an accuracy of less than 2 micrometers, ensuring that the wear condition of the electrode can be accurately captured. Discharge pulse counting: By analyzing the number of valid electric spark discharges (excluding invalid short-circuit or no-load signals) and combining them with the mathematical model of material removal, the total amount of electrode loss is calculated. If wear on one side of the electrode exceeds 10 micrometers, the system will automatically generate a three-dimensional compensation map and adjust the processing path. Each compensation will not exceed 5 micrometers to avoid excessive compensation in one cut, which would affect the accuracy. At the same time, if the electrode wear rate is found to be too fast (for example, much faster than normal), the current will be automatically reduced or the discharge interval will be lengthened to reduce electrode wear.

[0050] Compared to traditional manual measurement or fixed compensation, it is more accurate and intelligent, and can adjust processing parameters in real time to avoid dimensional deviations caused by electrode wear, ensuring that the accuracy of turbine blades is controlled within ±5 micrometers, improving yield, and reducing rework and scrap rates.

[0051] In summary, compared with existing processes, electrical discharge machining (EDM) has the following four advantages: First, for the challenging task of machining high-hardness single-crystal materials, electrical discharge machining (EDM) utilizes the characteristics of high-energy-density pulsed discharge to easily handle metal materials of any hardness, completely solving the problems of severe wear and low efficiency of traditional cutting tools. It is particularly suitable for the precision machining needs of high-hardness and high-strength alloys. Secondly, regarding dimensional accuracy control, this invention can stably achieve a precision of 0.02–0.03 mm using electrical discharge machining (EDM). mm The machining precision is perfectly matched to the machining precision requirements of the turbine disk and shaft, ensuring that the surface quality can stably reach the VDI12 level and improving the assembly precision of the entire rotor assembly. Third, for complex open structures in the root extension section, electrical discharge machining can form a tapered open complex structure in one step, including the multi-sided side structure of the flange and damping platform, which solves the problem of conventional machining difficulties and greatly improves machining efficiency. Fourth, in terms of adaptability to mass production, CNC EDM equipment has significant advantages. CNC EDM can achieve fully automated production, completing the entire process of roughing, semi-finishing and finishing on the same machine tool, meeting the needs of mass production of aero-engine blades, and achieving a perfect combination of high efficiency and low cost.

[0052] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A high-precision turbine blade casting, comprising a blade body (1), an extension root (2), and a tenon tooth (3), characterized in that: The blade (1), root extension (2) and tenon (3) are integrally cast. The root extension (2) includes a rim plate (4) and a damping platform (5). The damping platform (5) connects the rim plate (4) and the tenon (3). The rim plate (4) and the damping platform (5) adopt a transition arc surface design. The root extension (2) is conical.

2. A method for manufacturing a high-precision turbine blade, used to manufacture the high-precision turbine blade of claim 1, characterized in that: Includes the following steps: S1, Casting structure setting: The turbine blade is designed as an integral cast structure, with the lower edge of the flange plate and the damping platform set as the root extension part, specifically an integral conical structure; S2, Directional solidification casting: Using single-crystal directional solidification process, a blade casting with the integral conical root extension section is cast; S3, Machining and Forming: The tenons are machined using grinding, and the flange and damping platform structure are machined on the root extension section using electrical discharge machining.

3. The method for manufacturing a high-precision turbine blade according to claim 2, characterized in that: The volume of the conical structure completely encompasses the original lower edge plate and damping boss structure, and dimensional allowances are provided in all directions.

4. The method for manufacturing a high-precision turbine blade according to claim 2, characterized in that: The specific process of step S2 is as follows: S21, Prepare blade wax mold based on blade design model; S22, a blade wax mold is formed by pressure injection using a wax injection device, and the sprue, crystal selector, blade, etc. are bonded together to form a blade casting wax mold; S23, prepare a ceramic shell on the surface of the wax mold, heat to dewax and calcine the ceramic shell at high temperature; S24 uses directional solidification equipment to heat the blade mold shell, melts the single crystal high-temperature alloy into molten metal, and then pours it into the ceramic mold shell. S25 uses a directional pulling mechanism and a heat insulation device to move the ceramic shell from the high temperature zone to the low temperature zone, forming a high temperature gradient along the blade axis. S26, the single-crystal blade solidifies, crystallizes and grows under the axial temperature gradient. After competing to grow into a single grain through the crystal selector at the bottom of the blade, it continues to solidify into a single-crystal blade inside the ceramic shell of the blade.

5. The method for manufacturing a high-precision turbine blade according to claim 4, characterized in that: The blade root extension section of the blade wax mold is set in a conical cavity, which completely encloses the original lower edge plate and damping boss structure.

6. The method for manufacturing a high-precision turbine blade according to claim 2, characterized in that: The specific process of step S3 is as follows: S31, calibrate the reference surface, use a six-point positioning fixture to clamp the blade body, set the grinding tool and compile the grinding program based on the tenon parameters; S32, set the grinding parameters and perform the grinding process; S33, coordinate measuring machine for tenon size detection; S34, clamp the blade casting with the tenon teeth machined, and set the electrode based on the final blade structure; S35, sets multi-stage discharge parameters for layered processing; S36, online detection of machining dimensions, and reprocessing of out-of-tolerance areas.

7. The method for manufacturing a high-precision turbine blade according to claim 6, characterized in that: The layered processing includes: Roughing stage: peak current 8-15A, pulse width 300±30ti, layered removal of excess material; Finishing stage: peak current 6~10A, pulse width 260±20ti, forming edge plate and root extension structure; Micro-finishing stage: peak current 6-8A, pulse width 200±15ti, polishing the blade surface.

8. The method for manufacturing a high-precision turbine blade according to claim 7, characterized in that: During the finishing stage, the electrode wear is monitored in real time, and the electrode feed path is dynamically adjusted by using dual feedback of optical measurement and discharge pulse counting.

9. The method for manufacturing a high-precision turbine blade according to claim 7, characterized in that: The layered processing process employs a multi-angle nozzle array for EDM flushing. The flushing fluid is pressure-sprayed after two-stage filtration, and a temperature sensor is installed in the processing area for closed-loop temperature control.

10. A method for manufacturing a high-precision turbine blade according to claim 8, characterized in that: The optical measurement and discharge pulse counting are specifically as follows: Optical measurements are performed by scanning the electrode morphology using a laser displacement sensor, with a measurement accuracy of ≤2μm. Discharge pulse counting is performed by statistically analyzing effective discharge pulses and combining them with a material removal model to calculate cumulative loss. When the electrode single-sided loss is detected to be ≥10μm, a three-dimensional compensation map is generated and the CNC axis feed path is adjusted with a compensation step size ≤5μm. At the same time, based on the abnormal loss rate, the peak current is reduced or the pulse interval is extended. After processing 0.05mm of depth, the feed is paused for optical calibration, and the loss is output after processing is completed.

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