Machining method for long-journal centrifugal impeller of aero-engine

Abstract

The invention relates to a machining method for a long-journal centrifugal impeller of an aero-engine, and relates to the field of centrifugal impeller machining. Through detailed preparation procedures before welding, hot pressing assembly, electron beam welding and subsequent finish machining and special treatment steps, high accuracy and reliability of the impeller assembly are ensured. According to the method, the mass of the impeller is reduced as much as possible on the premise that enough strength is guaranteed, the inertia and fuel consumption of a whole engine system are reduced, the smoothness of the blades is improved through a strict surface treatment process, and therefore the friction loss in the running process is reduced. Particularly, the double-disc clamping type welding clamp is adopted for electron beam welding, the precision and stability of the long-journal centrifugal impeller in the machining process are effectively guaranteed, and the quality of a final product is improved. In addition, the welded impeller assembly is subjected to X-ray inspection and vacuum destressing treatment, and finish machining after welding is carried out, so that the durability and safety of the impeller are further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal impeller processing, and in particular to a processing method for a long-journal centrifugal impeller of an aero-engine. Background Art

[0002] As the core component of an aircraft engine, the centrifugal impeller compresses and accelerates the gas through high-speed rotation, providing a stable and high-pressure airflow for the combustion chamber, thereby ensuring that the engine can run efficiently and smoothly. Since the beginning of the aviation industry in the early 20th century, centrifugal impeller technology has grown and developed with it. Early designs were relatively simple, and limited by the level of material science and technology at the time, these initial attempts laid the foundation, but were far from meeting the needs of the modern aviation industry. With the development of the times, especially the advent of the jet era after World War II, the requirements for aircraft performance have become increasingly stringent, prompting engineers to continuously improve the design and manufacturing process of centrifugal impellers. Today, thanks to the application of advanced computational fluid dynamics (CFD) analysis tools and the development of new materials such as high-strength and lightweight materials such as titanium alloys, modern centrifugal impellers have not only made leaps and bounds in structural complexity, but have also made remarkable achievements in improving aerodynamic efficiency, reducing weight, and enhancing durability.

[0003] However, in the face of growing environmental awareness and strict emission standards around the world, how to further improve the efficiency of centrifugal impellers, reduce energy consumption, and reduce the impact on the environment has become an important problem in the field of contemporary aviation engineering. In order to meet the above challenges, researchers and engineers are committed to exploring more optimized design concepts and technical means. For example, minimizing the mass of the impeller while ensuring sufficient strength to reduce the inertia and fuel consumption of the entire engine system; developing new processing methods to improve the surface finish of the blades and thus reduce friction losses; using advanced clamping methods to ensure the accuracy and stability of long-neck centrifugal impellers during processing are all key research directions. In addition, considering the special status of aircraft engines as the "heart" of aircraft, any slight design defects or manufacturing errors may affect the safety of flight. Therefore, in-depth exploration of the manufacturing process of centrifugal impellers, especially the treatment solutions for key parts such as the long-neck part, is crucial to ensure the safe and reliable operation of the engine and even the entire aircraft. Summary of the invention

[0004] The purpose of the present invention is to provide a method for processing a long-neck centrifugal impeller of an aero-engine to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a method for processing a long-neck centrifugal impeller of an aircraft engine, wherein the long-neck centrifugal impeller is formed by combining a front neck and a centrifugal impeller through electron beam welding, and the method comprises: S1, performing a pre-welding preparation process on the front journal, wherein the pre-welding preparation process of the front journal at least includes material preparation, rough turning, stress relief, fine turning, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing, to obtain a front journal part to be welded; S2, performing a pre-welding preparation process on the centrifugal impeller, the pre-welding preparation process of the centrifugal impeller at least includes material preparation, rough turning, milling of angular grooves, rough milling of blade profiles and flow channels, stress relief, fine turning, expanding and repairing angular grooves, fine milling of blade profiles and flow channels, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing, to obtain a centrifugal impeller to be welded; S3, hot pressing the front journal member to be welded and the centrifugal impeller member to be welded, wherein the matching stoppers of the front journal member to be welded and the centrifugal impeller member to be welded are interference fit, and an assembled impeller assembly is obtained; S4, placing the assembled impeller assembly into a double-disc clamping welding fixture for electron beam welding to obtain a welded impeller assembly; S5, performing X-ray inspection and vacuum stress relief on the welded impeller assembly, and performing post-weld finishing on the welded impeller assembly after stress relief, wherein the post-weld finishing at least includes datum repair, precision turning, and grinding, to obtain a finished impeller assembly; S6. Place the finely machined impeller assembly into a keyway machining fixture for involute spline milling, end face groove and circumferential hole machining to obtain the long-neck centrifugal impeller.

[0006] In a possible implementation, in step S1 and step S2: The welding grooves of the front journal component to be welded and the centrifugal impeller component to be welded are set as a locking bottom structure, a 1-2mm wide exhaust groove is set at the root of the locking bottom structure, and a 0.1-0.2mm shrinkage amount is reserved at the welding groove.

[0007] In a possible implementation, in step S3: The front journal member to be welded is heated to 80-110°C and kept warm for 30 minutes, and then hot-pressed assembled with the centrifugal impeller member to be welded, ensuring that the gap at the assembly is no greater than 0.03 mm; The interference amount of the matching stop between the front journal component to be welded and the centrifugal impeller component to be welded is 0.02-0.04mm.

[0008] In a possible implementation, before step S4, the method further includes: The welding test piece is used to simulate the parts to be welded. After the test piece is dissected, its metallographic structure, performance, surface and internal quality are checked to see if they fully meet the requirements, so as to determine the welding parameters.

[0009] In a possible implementation, in step S4: The double-disc clamping welding fixture includes a welding positioning disk, an anti-rotation disk, a hexagon socket screw, a screw, a first pressure plate, a dish-shaped elastic washer, and a first nut. The welding positioning disk is connected to the welding equipment. The anti-rotation disk is installed on the connecting side of the welding positioning disk and the welding equipment through the hexagon socket screw. The screw is inserted into the center hole of the welding positioning disk. After the assembly, the impeller assembly is sleeved on the screw. The first pressure plate and the dish-shaped elastic washer are successively inserted into the side of the screw away from the welding positioning disk, and are tightened and fixed by the first nut.

[0010] In a possible implementation, in step S5: The temperature for vacuum stress relief of the welded impeller assembly is 500°C±10°C, which is kept for 4h±10min and then furnace cooled.

[0011] In a possible implementation, in step S6: The keyway processing fixture includes a connecting seat, a core rod, a second pressure plate, and a second nut. The connecting seat is connected to the processing equipment, the core rod is inserted into the center hole of the connecting seat, the impeller assembly after fine processing is sleeved on the core rod, and the second pressure plate is inserted into the side of the core rod away from the connecting seat and is tightened and fixed by the second nut.

[0012] In a possible implementation, the front journal and the centrifugal impeller blank bars are both made of titanium alloy TC11.

[0013] The beneficial effects brought about by the technical solution provided by the present invention include at least: The processing method of the long-neck centrifugal impeller of the aircraft engine provided by the technical solution ensures the high accuracy and reliability of the impeller assembly through detailed pre-welding preparation process, hot pressing assembly, electron beam welding, and subsequent finishing and special processing steps. This method not only minimizes the mass of the impeller while ensuring sufficient strength, which helps to reduce the inertia and fuel consumption of the entire engine system, but also improves the finish of the blades through a strict surface treatment process, thereby reducing the friction loss during operation. In particular, the use of a double-disc clamping welding fixture for electron beam welding effectively guarantees the accuracy and stability of the long-neck centrifugal impeller during the processing process and improves the quality of the final product. In addition, the durability and safety of the impeller are further enhanced by performing X-ray inspection and vacuum stress relief treatment on the impeller assembly after welding, and implementing post-welding finishing. This high-quality processing technology plays an important role in improving the working efficiency and extending the service life of aircraft engines, and also contributes to promoting the technological progress and sustainable development of the aviation industry in my country and even the world. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0015] Figure 1 A flow chart of a method for machining a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown.

[0016] Figure 2 A detailed process route diagram of a method for machining a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown.

[0017] Figure 3 A diagram showing the state before welding of the front journal of a method for machining a long journal centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown.

[0018] Figure 4 A diagram of a centrifugal impeller before welding is shown, showing a method for machining a centrifugal impeller with a long shaft neck for an aircraft engine provided by an exemplary embodiment of the present invention.

[0019] Figure 5 A state diagram of electron beam welding of a method for processing a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown.

[0020] Figure 6 A schematic diagram of a double-disc clamping welding fixture is shown for a method for machining a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention.

[0021] Figure 7 A schematic diagram of the repair reference of a welded impeller assembly during post-welding finishing of a method for machining a long-neck centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown.

[0022] Figure 8 A schematic diagram of an impeller assembly after fine machining of a method for machining a long-neck centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown.

[0023] Fig. 9 A schematic diagram of a keyway machining fixture for a machining method of a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1 A flowchart of a method for machining a long-journal centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown. Figure 2 A detailed process route diagram of a method for machining a long-neck centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown. The long-neck centrifugal impeller is assembled and machined by electron beam welding a front neck and a centrifugal impeller. The method comprises: Step S1, performing a pre-welding preparation process on the front axle neck, the pre-welding preparation process of the front axle neck at least includes material preparation, rough turning, stress relief, fine turning, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing to obtain the front axle neck part to be welded.

[0027] In one example, Figure 3 A diagram of the front neck state before welding of a method for processing a long-neck centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown. Except for the end face and inner hole marked with thick solid lines in the figure, which have been processed to the final state, a 1mm margin is reserved on one side of the remaining positions.

[0028] Specifically, the pre-welding preparation process of the front journal is to process the front journal to a size close to the final size, with only a 1mm single-sided margin reserved for final finishing at certain key locations. Rough turning is to remove most of the blank margin to make the workpiece close to the final shape and size; while stress relief annealing is to eliminate the internal stress generated during cold processing to avoid deformation or cracking during subsequent processing or use. Finish turning ensures that the workpiece surface meets high precision requirements, providing a good foundation for subsequent assembly.

[0029] Step S2, performing a pre-welding preparation process on the centrifugal impeller, the pre-welding preparation process of the centrifugal impeller at least includes material preparation, rough turning, milling of angular grooves, rough milling of blade profiles and flow channels, stress relief, fine turning, expanding and repairing angular grooves, fine milling of blade profiles and flow channels, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing to obtain the centrifugal impeller parts to be welded.

[0030] In the pre-welding preparation process of the above-mentioned step S1 and step S2, in order to ensure the axial and radial runout and coaxiality after welding and to enable self-centering during assembly, the welding grooves of the front journal part to be welded and the centrifugal impeller part to be welded are set as a bottom locking structure. Figure 5 The electron beam welding state diagram of a processing method for a long-journal centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown. A 1-2mm wide exhaust groove is provided at the root of the lock bottom structure, and a 0.1-0.2mm shrinkage is reserved at the welding groove. This design not only facilitates self-centering, but also effectively exhausts the gas generated during welding, prevents the formation of pore defects, and thus improves the quality of the weld.

[0031] In one example, the blank bars of the front journal and the centrifugal impeller of the present application are both made of titanium alloy TC11 / GJB2218A, which has excellent mechanical properties and corrosion resistance and is suitable for manufacturing high-performance aircraft engine components.

[0032] In one example, Figure 4 A diagram of the pre-welding state of a centrifugal impeller of a long-neck centrifugal impeller of an aircraft engine provided by an exemplary embodiment of the present invention is shown. Except for the end face, inner hole, and blade flow channel marked with thick solid lines in the figure, which have been processed to the final state, a 1mm margin is reserved on one side of the remaining positions.

[0033] Specifically, the pre-welding preparation process of the centrifugal impeller includes steps similar to those of the front journal, but also includes specific operations such as milling angular grooves, rough milling of blade profiles and flow channels, expanding and repairing angular grooves, and fine milling of blade profiles and flow channels. This is because the structure of the centrifugal impeller is more complex, and the blade shape and its internal flow channels need to be finely processed to ensure its aerodynamic performance. Similarly, after completing the above processing, in addition to the key areas marked in the figure that have reached the final state, the rest of the parts also reserve a single-sided allowance of 1mm to facilitate subsequent fine processing adjustments.

[0034] Step S3, hot pressing the front journal component to be welded and the centrifugal impeller component to be welded, the matching stoppers of the front journal component to be welded and the centrifugal impeller component to be welded are interference fit, and the assembled impeller assembly is obtained.

[0035] In an embodiment of the present application, the front shaft neck part to be welded is heated to 80-110°C and kept warm for 30 minutes, and then hot-pressed assembled with the centrifugal impeller part to be welded to ensure that the gap at the assembly is no more than 0.03mm; the interference fit of the mating stop of the front shaft neck part to be welded and the centrifugal impeller part to be welded is 0.02-0.04mm.

[0036] Specifically, the front journal to be welded is heated to 80-110℃ and kept warm for 30 minutes before being assembled with the centrifugal impeller to be welded. This process utilizes the thermal expansion and contraction characteristics of the material, so that the front journal expands when heated, so that it can smoothly cooperate with the centrifugal impeller to achieve interference fit. When the temperature gradually returns to room temperature, the front journal shrinks to form a tight mechanical connection, ensuring that the gap at the assembly is no more than 0.03mm, while maintaining an interference of 0.02-0.04mm. This hot pressing assembly method has several significant advantages: first, it can complete the tight fit between parts without applying excessive external pressure, avoiding damage or deformation problems that may be caused by forced assembly; second, by strictly controlling the heating temperature and holding time, it can be ensured that the workpiece will not undergo metallographic changes due to excessive temperature, affecting its mechanical properties; in addition, the use of interference fit not only improves the assembly accuracy, but also enhances the fatigue resistance and sealing of the interface, which is particularly important for aircraft engines that withstand high speed and high pressure environments.

[0037] In order to ensure the success rate and quality of hot press assembly, parameters such as heating temperature, holding time and cooling rate must be accurately monitored during the operation. For example, heating within the range of 80-110°C specified in this embodiment and maintaining sufficient time to allow the heat to be evenly distributed throughout the component can allow the front journal to fully expand without damaging the material structure. After assembly, as the temperature drops, the front journal naturally shrinks and tightly combines with the centrifugal impeller component to form a solid whole, that is, the rear impeller assembly. This method can not only effectively prevent loosening, but also reduce vibration transmission, thereby improving the stability and efficiency of the entire engine system.

[0038] Step S4, placing the assembled impeller assembly into a double-disc clamping welding fixture for electron beam welding to obtain a welded impeller assembly.

[0039] It is worth mentioning that before step S4, it also includes: simulating the parts to be welded by welding test pieces, dissecting the test pieces to check whether their metallographic structure, performance, surface and internal quality fully meet the requirements, so as to determine the welding parameters. This step is crucial to ensure the quality of welding and the reliability of subsequent products, because it allows engineers to identify and solve potential problems in advance, thus avoiding unnecessary rework or scrap.

[0040] In the embodiments of the present application, Figure 6 A schematic diagram of a double-disc clamping welding fixture for a method of processing a long-journal centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown. The double-disc clamping welding fixture comprises a welding positioning disc 1, an anti-rotation disc 2, a hexagon socket screw 7, a screw 4, a first pressure plate 3, a dish-shaped elastic washer 5, and a first nut 6. The welding positioning disc 1 is connected to the welding equipment. The anti-rotation disc 2 is installed on the side of the welding positioning disc 1 connected to the welding equipment through the hexagon socket screw 7. The screw 4 is inserted into the center hole of the welding positioning disc 1. After assembly, the impeller assembly is sleeved on the screw 4. The first pressure plate 3 and the dish-shaped elastic washer 5 are inserted in sequence on the side of the screw 4 away from the welding positioning disc 1, and are tightened and fixed by the first nut 6. The double-disc clamping welding fixture ensures that the welding process will not loosen due to weld shrinkage, the clamping force is constant, and it is not affected by thermal expansion and contraction. Among them, the impeller assembly after assembly needs to be loaded into the double-disc clamping welding fixture and the welding needs to be completed within 8 hours. This time limit is to ensure that the material properties and process conditions during the welding process are in the best state, and to avoid changes in material properties or interference from environmental factors due to waiting too long, which will affect the welding quality. Electron beam welding itself is a high-precision, low-heat input welding method that can achieve deep penetration in a short time while reducing the thermal impact on the surrounding area. It is very suitable for difficult-to-weld materials such as titanium alloys.

[0041] Step S5, X-ray inspection and vacuum stress relief are performed on the welded impeller assembly, and post-welding finishing is performed on the welded impeller assembly after stress relief, and the post-welding finishing includes at least repairing the datum (see Figure 7 )、Fine Turning(See Figure 8 ), and grinding to obtain the finished impeller assembly.

[0042] In the embodiment of the present application, the temperature for vacuum stress relief of the impeller assembly after welding is 500°C±10°C, and the temperature is kept for 4h±10min and then furnace cooled.

[0043] Specifically, X-ray inspection is used to evaluate whether there are internal defects in the weld area, such as cracks, pores or lack of fusion, which is an indispensable part of ensuring welding quality. X-ray non-destructive testing can intuitively display the internal structure of the weld, helping engineers to promptly discover and solve potential quality problems, thereby preventing unqualified products from entering the next process. Next is vacuum stress relief, which is a heat treatment process for the welded impeller assembly under specific conditions (such as a temperature of 500℃±10℃, holding for 4 hours±10 minutes, and then furnace cooling) to eliminate the residual stress generated during the welding process. Due to uneven local heating and cooling rates during welding, internal stresses will be generated in the workpiece, which may cause deformation or cause fatigue fractures in long-term use. Therefore, by controlling the heating and cooling rates, these adverse effects can be effectively reduced or eliminated without affecting the mechanical properties of the material. Choosing to perform this process in a vacuum can also prevent oxidation and other surface contamination, and maintain the original physical properties of the material. After completing vacuum stress relief, the welded impeller assembly is followed by post-welding finishing. Finishing includes at least three main steps: datum repair, fine turning, and grinding. The purpose of re-datuming is to redefine or restore key dimensional reference points to ensure that subsequent processing operations can achieve the required accuracy requirements; finishing turning further improves the surface quality and dimensional accuracy of the parts, making the appearance closer to the design value; and grinding, as the last step, can not only obtain an extremely smooth surface finish, but also correct small errors introduced by the previous process to ensure that all geometric parameters meet strict standards.

[0044] Step S6, placing the finely machined impeller assembly into a keyway machining fixture for involute spline milling, end face groove, and circumferential hole machining to obtain a long-neck centrifugal impeller.

[0045] In the embodiments of the present application, Fig. 9A schematic diagram of a keyway processing fixture for a method for processing a long-neck centrifugal impeller of an aero-engine provided by an exemplary embodiment of the present invention is shown. The keyway processing fixture includes a connecting seat 8, a core rod 9, a second pressing plate 10, and a second nut 11. The connecting seat 8 is connected to the processing equipment, and the core rod 9 is inserted into the center hole of the connecting seat 8 to ensure the stability and concentricity of the entire processing. After fine processing, the impeller assembly is sleeved on the core rod 9, and the second pressing plate 10 is inserted into the side of the core rod 9 away from the connecting seat 8, and is tightened and fixed by the second nut 11. This design ensures that the workpiece will not be displaced or loosened during the entire processing process, thereby improving the processing accuracy. The milling of the involute spline on both sides, the end face groove, and the circumferential hole processing are completed by one clamping, which greatly reduces the clamping time. The use of such a keyway processing fixture and technical solution can not only meet the requirements of high precision, but also effectively shorten the manufacturing cycle and reduce production costs. This is particularly important for the aero-engine manufacturing industry that pursues high performance and high quality standards. By optimizing the fixture design and processing process, manufacturers can improve productivity while ensuring product quality and enhance market competitiveness.

[0046] In summary, the processing method of the long-neck centrifugal impeller of an aero-engine provided by the technical solution ensures the high accuracy and reliability of the impeller assembly through detailed pre-welding preparation procedures, hot pressing assembly, electron beam welding, and subsequent finishing and special processing steps. This method not only minimizes the mass of the impeller while ensuring sufficient strength, which helps to reduce the inertia and fuel consumption of the entire engine system, but also improves the finish of the blades through a strict surface treatment process, thereby reducing the friction loss during operation. In particular, the use of a double-disc clamping welding fixture for electron beam welding effectively ensures the accuracy and stability of the long-neck centrifugal impeller during the processing process and improves the quality of the final product. In addition, by performing X-ray inspection and vacuum stress relief treatment on the impeller assembly after welding, and implementing post-welding finishing, the durability and safety of the impeller are further enhanced. This high-quality processing technology plays an important role in improving the working efficiency and extending the service life of aero-engines, and also contributes to promoting the technological progress and sustainable development of the aviation industry in my country and even the world.

[0047] It should be understood that the specific examples herein are only intended to help those skilled in the art to better understand the present disclosure, rather than to limit the scope of the present invention.

[0048] It is understood that in the various implementations of this specification, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the present disclosure.

[0049] It can be understood that the various implementation modes described in this specification can be implemented individually or in combination, and the present disclosure is not limited to this.

[0050] Unless otherwise stated, all technical and scientific terms used in this disclosure have the same meaning as those generally understood by those skilled in the art of the technical field of this specification. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the scope of this specification. The term "and / or" used in this specification includes any and all combinations of one or more related listed items. The singular forms of "a", "above", and "the" used in this disclosure and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0051] The above is only a specific implementation of this specification, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this specification, which should be included in the protection scope of this specification. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for processing an aero-engine long-journal centrifugal impeller, characterized in that: The long-journal centrifugal impeller is formed by combining a front journal and a centrifugal impeller through electron beam welding, and the method comprises: S1, performing a pre-welding preparation process on the front journal, wherein the pre-welding preparation process of the front journal at least includes material preparation, rough turning, stress relief, fine turning, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing, to obtain a front journal part to be welded; S2, performing a pre-welding preparation process on the centrifugal impeller, the pre-welding preparation process of the centrifugal impeller at least includes material preparation, rough turning, milling of angular grooves, rough milling of blade profiles and flow channels, stress relief, fine turning, expanding and repairing angular grooves, fine milling of blade profiles and flow channels, clamp repair, marking, intermediate inspection, fluorescent inspection, cleaning, final inspection, and packaging and warehousing, to obtain a centrifugal impeller to be welded; S3, hot pressing the front journal member to be welded and the centrifugal impeller member to be welded, wherein the matching stoppers of the front journal member to be welded and the centrifugal impeller member to be welded are interference fit, and an assembled impeller assembly is obtained; S4, placing the assembled impeller assembly into a double-disc clamping welding fixture for electron beam welding to obtain a welded impeller assembly; S5, performing X-ray inspection and vacuum stress relief on the welded impeller assembly, and performing post-weld finishing on the welded impeller assembly after stress relief, wherein the post-weld finishing at least includes datum repair, precision turning, and grinding, to obtain a finished impeller assembly; S6. Place the finely machined impeller assembly into a keyway machining fixture for involute spline milling, end face groove, and circumferential hole machining to obtain the long-neck centrifugal impeller.

2. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: In the steps S1 and S2: The welding grooves of the front journal component to be welded and the centrifugal impeller component to be welded are set as a locking bottom structure, a 1-2mm wide exhaust groove is set at the root of the locking bottom structure, and a 0.1-0.2mm shrinkage amount is reserved at the welding groove.

3. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: In step S3: The front journal member to be welded is heated to 80-110°C and kept warm for 30 minutes, and then hot-pressed assembled with the centrifugal impeller member to be welded, ensuring that the gap at the assembly is no greater than 0.03 mm; The interference amount of the matching stop between the front journal component to be welded and the centrifugal impeller component to be welded is 0.02-0.04mm.

4. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: Before step S4, the method further includes: The welding test piece is used to simulate the parts to be welded. After the test piece is dissected, its metallographic structure, performance, surface and internal quality are checked to see if they fully meet the requirements, so as to determine the welding parameters.

5. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: In step S4: The double-disc clamping welding fixture includes a welding positioning disk, an anti-rotation disk, a hexagon socket screw, a screw, a first pressure plate, a dish-shaped elastic washer, and a first nut. The welding positioning disk is connected to the welding equipment. The anti-rotation disk is installed on the connecting side of the welding positioning disk and the welding equipment through the hexagon socket screw. The screw is inserted into the center hole of the welding positioning disk. After the assembly, the impeller assembly is sleeved on the screw. The first pressure plate and the dish-shaped elastic washer are successively inserted into the side of the screw away from the welding positioning disk, and are tightened and fixed by the first nut.

6. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: In step S5: The temperature for vacuum stress relief of the welded impeller assembly is 500°C±10°C, which is kept for 4h±10min and then furnace cooled.

7. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: In step S6: The keyway processing fixture includes a connecting seat, a core rod, a second pressure plate, and a second nut. The connecting seat is connected to the processing equipment, the core rod is inserted into the center hole of the connecting seat, the impeller assembly after fine processing is sleeved on the core rod, and the second pressure plate is inserted into the side of the core rod away from the connecting seat and is tightened and fixed by the second nut.

8. The method for machining an aero-engine long-journal centrifugal impeller according to claim 1, characterized in that: The blank bars of the front journal and the centrifugal impeller are both made of titanium alloy TC11.

Images