A method of manufacturing an aeroengine rotor

Abstract

The application discloses a method for manufacturing an aero-engine rotor, which comprises a disk friction welding step and a rotating residual stress relieving step. In the rotating residual stress relieving step, a trapezoidal spectrum comprising a variable-speed stage and a constant-speed stage is loaded to relieve the welding residual stress. The method can relieve the residual stress caused by welding step by step in the manufacturing process of a multi-stage welded disk, is simple, and effectively avoids the risks of deformation and cracking caused by residual stress accumulation, thereby improving the quality of the finished disk.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aero-engines, and particularly relates to a manufacturing method of an aero-engine rotor. BACKGROUND

[0002] With the continuous progress of aero-engine technology, the structure of the engine rotor is increasingly complex, and the performance requirements of the connecting parts are increasingly high. At the same time, with the progress of material technology, more and more difficult-to-weld alloys such as titanium alloy and nickel alloy are applied to the manufacturing of aero-engine rotors, making it difficult for traditional welding processes to be applied to the manufacturing of engine rotors. As an advanced solid-state welding process, friction welding has become the mainstream process for the manufacturing of aero-engine rotors due to its high reliability and energy saving and material saving advantages.

[0003] Friction welding belongs to a solid-state welding process, and heat is provided by mutual friction of the surfaces to be welded during welding, and pressure is provided to the welding surface to make the welding surface joint together. During this process, the material at the welding joint position undergoes severe plastic deformation, resulting in a very high residual stress in the welding structure. The aero-engine rotor manufactured by using the friction welding process has a residual stress in the welding structure, which is mainly circumferential residual stress, accompanied by certain radial residual stress. In some examples, the circumferential residual stress value is close to the yield strength of the material, which causes great hidden troubles to the fatigue performance and dimensional stability of the aero-engine rotor.

[0004] The conventional method for eliminating residual stress is post-weld heat treatment, but the aero-engine rotor structure is complex, and is often assembled by multiple disc parts through multiple welding. Repeated heat treatment will have an adverse effect on the long-time performance of the disc body. And for the rotor after multiple welding, uniform heat treatment is often performed, but the residual stress of the previous weld is not eliminated in time, the residual stress of the multiple welding process is accumulated, causing the overall torsional deformation of the rotor assembly, and even micro-cracks appear in the weld area. This has a very adverse effect on the production efficiency and product quality of the aero-engine rotor. SUMMARY

[0005] The present application provides a manufacturing method of an aero-engine rotor, which aims to provide an integrated process for friction welding of the disc and eliminating the residual stress of the welding structure without affecting the long-time performance of the disc body.

[0006] A method for manufacturing an aero-engine rotor, comprising a disk friction welding step and a rotating residual stress elimination step. In the rotating residual stress elimination step, the rotating load loading frequency spectrum is a cyclic trapezoidal spectrum, comprising a variable speed stage and a uniform speed stage, and the variable speed stage is divided into an acceleration stage and a deceleration stage. The rotation provides an external stress load for the disk welding part to timely eliminate the residual stress of the weld structure, avoid the adverse effects of repeated heat treatment on the long-term performance of the disk, and avoid the residual stress accumulation hidden danger after multi-stage welding and unified heat treatment.

[0007] Further, the rotating residual stress elimination step eliminates the circumferential residual stress through the variable speed stage and eliminates the radial residual stress through the uniform speed stage.

[0008] Further, the calculation method of the rotating load loading frequency spectrum is:

[0009] S1. According to the metallic material manual, determine the performance parameters of the aero-engine rotor metal material at the processing temperature. S2. According to the size of the aero-engine rotor and the welding parameters, simulate the calculation to determine the numerical range of the radial and circumferential residual stress of the welding area, and the external stress required to eliminate the residual stress. S3. According to the size of the rotor, calculate the rotating speed when the radial equivalent stress can eliminate the radial residual stress. S4. According to the size of the rotor, calculate the angular acceleration when the circumferential equivalent stress can eliminate the circumferential residual stress. S5. According to the numerical values calculated by S3 and S4 and the numerical value distribution of the residual stress obtained by simulation calculation, determine the time of the variable speed stage and the uniform speed stage and the total loading time in each loading cycle.

[0010] As an option, the variable speed stage comprises an acceleration stage for eliminating the circumferential residual stress and a deceleration stage with low angular acceleration. The circumferential stress generated by the rapid acceleration eliminates the circumferential residual stress of the weld structure, and the deceleration is completed at a lower acceleration after the uniform speed stage.

[0011] As an option, the variable speed stage comprises an acceleration stage with low angular acceleration and a deceleration stage for eliminating the circumferential residual stress. The acceleration is completed at a lower acceleration, and the rapid deceleration is performed after the uniform speed stage, and the circumferential stress generated by the deceleration eliminates the circumferential residual stress of the weld structure.

[0012] As preferred, the processing temperature of the residual stress elimination step is 200-350℃.

[0013] As preferred, the disk friction welding step uses the process of inertia friction welding.

[0014] As preferred, the inertia friction welding adopts the welding parameters that the rotating end rotating speed is 300-600 rpm, the moment of inertia is 1000 Kg·m 2-5000 kg·m 2 The pressure during the upsetting stage is 100MPa-500MPa.

[0015] Preferably, the rotational stress relief step is performed on the friction welding equipment, which allows for immediate rotational stress relief after the friction welding step is completed, eliminating the need for equipment change and improving processing efficiency. Attached Figure Description

[0016] Figure 1 A schematic diagram of the equipment structure used in the manufacturing method of aero-engine rotors;

[0017] Figure 2 This is a trapezoidal spectrum diagram of the residual stress elimination step in the manufacturing method of aero-engine rotors, where the horizontal axis represents time and the vertical axis represents rotational speed.

[0018] The above-described drawings are intended to provide a detailed description of the present invention, enabling those skilled in the art to accurately understand the technical concept of the invention, and do not constitute a specific limitation on the embodiments of the present invention. It should be understood that, for ease of description, the above-described drawings only schematically depict the parts related to the technical features of the present invention, and do not strictly depict all equipment, parts, and details according to actual scale.

[0019] Meaning of reference numerals in the attached diagram:

[0020] 1- Rotary end positioning fixture; 2- Rotary end bearing; 3- Rotary end body; 4- Flywheel; 5- Rotary end impeller; 6- Moving end impeller; 7- Moving end fixing fixture; 8- Moving end positioning fixture; 9- Moving end bearing; 10- Moving end body; 11- Moving end push rod; 12- Moving end hydraulic cylinder. Detailed Implementation

[0021] This invention provides a method for manufacturing an aero-engine rotor, employing methods such as... Figure 1The device shown comprises a rotating end and a moving end. The rotating end is connected to a drive motor, which in turn connects to a rotating end positioning fixture 1. A rotating end bearing 2 is mounted on the rotating end body 3, allowing the rotating end positioning fixture 1 to rotate under the drive motor's influence. A flywheel 4 is mounted on the rotating end positioning fixture 1, storing rotational kinetic energy using the flywheel's inertia after the drive motor starts. A rotating end impeller 5 is coaxially mounted at the end of the rotating end positioning fixture 1. The moving end includes a moving end hydraulic cylinder 12 and a moving end push rod 11 connected thereto, used to provide the pressure required for the friction welding upsetting and holding stages. A moving end positioning fixture 8 is mounted on the moving end body 10 via a moving end bearing 9. A moving end impeller 6 is coaxially mounted at the end of the moving end positioning fixture 8, with its welding surface opposite to the welding surface of the rotating end impeller 5. A moving end fixing fixture 7 clamps the edge of the moving end impeller 6 to prevent it from rotating with the rotating end impeller 5 during the welding process.

[0022] In the friction welding step of the bladed disk, the first step is to perform pretreatment: heat treatment is carried out on the bladed disk blank according to the drawings and process requirements to eliminate the residual stress caused by the previous processing; then the welding surface is rough processed before welding to remove the surface oxide scale, while retaining a welding allowance of 1.5mm-3mm on each side.

[0023] Next, inertial friction welding will be performed. (Press...) Figure 1 The rotating end impeller 5 and the moving end impeller 6 are installed as shown, and locked to the rotating end positioning clamp 1 and the moving end positioning clamp 8 respectively. Simultaneously, the moving end impeller 6 is clamped with the moving end fixing clamp 7. The drive motor is started, causing the rotating end positioning clamp 1, flywheel 4, and rotating end impeller 5 to rotate. When the speed reaches 300rpm-600rpm, the drive motor is disengaged from the rotating end positioning clamp 1, allowing the rotating end impeller 5 to rotate freely under the inertia of the flywheel 4. At this point, the moment of inertia is within the range of 1000Kg·m. 2 -5000 kg·m 2 Simultaneously, the moving end hydraulic cylinder 12 is activated, pushing the moving end push rod 11 towards the rotating end. Using the moving end positioning fixture 8, the moving end impeller 6 and the rotating end impeller 5 are pressed together along the welding surface for friction welding. The upsetting pressure is 100MPa-500MPa. At this time, due to the restriction of the moving end positioning fixture 7, the moving end impeller 6 does not rotate. As the rotational speed of the rotating end gradually decreases until it stops, the pressure is maintained at 100MPa-500MPa for 10-15 seconds until the welding surface stabilizes, completing the welding of the rotating end impeller 5 and the moving end impeller 6.

[0024] At this point, due to the intense plastic deformation of the weld surface, high residual stress remains in the weld microstructure, primarily distributed in the circumferential direction, accompanied by a certain amount of radial residual stress. To prevent these residual stresses from adversely affecting the fatigue performance and dimensional stability of the aero-engine rotor, stress relief treatment is required.

[0025] The subsequent rotational stress relief step is performed directly on the original inertial friction welding equipment, without requiring disassembly or transfer of the workpiece. First, the moving end fixing fixture 7 is disengaged from the moving end impeller 6, allowing the welded impeller to rotate freely. Then, the flywheel 4 is removed to prevent its significant weight from consuming excessive kinetic energy during the rotational load-bearing process. The rotating end positioning fixture 1 is then reconnected to the drive motor. When the weld temperature cools to 200℃-350℃, the drive motor is started, cyclically outputting the rotational load in a trapezoidal spectrum. The trapezoidal spectrum is as follows: Figure 2 As shown, the process includes a variable speed phase and a constant speed phase. After the drive motor starts, it first rotates at a valley speed, then enters an acceleration phase where the speed reaches its peak. It then rotates at the peak speed while maintaining the load, followed by a deceleration phase where the speed decreases back to the valley speed, and the loading process repeats. During the constant speed phase, when the speed reaches its peak, the radial equivalent stress of the impeller weldment reaches its maximum, thus eliminating radial residual stress in the weld structure. During the variable speed phase, the circumferential equivalent stress from acceleration or deceleration can eliminate circumferential residual stress in the weld structure: rapid acceleration during the acceleration phase and slow deceleration during the deceleration phase can eliminate circumferential residual stress during acceleration; slow acceleration during the acceleration phase and sudden braking during the deceleration phase can eliminate circumferential residual stress during deceleration. The two methods of eliminating circumferential residual stress have opposite rotational directions.

[0026] After the rotational stress relief step is completed, wait for the bladed disk welded part to stop rotating, remove the part, and continue with subsequent processing.

[0027] The main parameters of the trapezoidal spectrum in the rotational residual stress elimination step include: peak rotational speed ω, loading angular acceleration a, acceleration time t1, constant speed time t2, deceleration time t3, and loading interval t4. Taking the elimination of circumferential residual stress through emergency braking during the deceleration phase as an example, the method for calculating the trapezoidal spectrum includes the following steps:

[0028] Step 1: Determine the statistical value of the yield strength of blade metal materials at 200℃-350℃ according to the metal properties handbook.

[0029] Step 2: Based on the bladed disk dimensions and welding parameters, perform simulation calculations to determine the numerical range of radial and circumferential residual stresses in the welding area. Then, determine the required stress values ​​and loading times to eliminate the residual stresses. Take the loading time required to eliminate circumferential stress as T1 and the loading time required to eliminate radial stress as T2. Typically, the equivalent stress required to eliminate residual stresses is numerically close to the material's yield strength.

[0030] Step 3: Based on the rotor dimensions, calculate the rotational speed ω when the radial equivalent stress during rotation can eliminate the radial residual stress, i.e., the peak rotational speed during the uniform speed stage.

[0031] Step 4: Based on the rotor dimensions, calculate the loading angular acceleration 'a' during emergency braking when the circumferential equivalent stress during rotation can eliminate the circumferential residual stress. The direction of the loading angular acceleration 'a' should be opposite to the direction of the circumferential residual stress.

[0032] Step 5: When the valley speed is very low and negligible, the emergency braking deceleration stage t3 = ω / a, which is the loading time for eliminating circumferential residual stress during the speed change stage within a single cycle. Therefore, the number of cycles N = T1 / t3. Furthermore, the peak constant speed rotation time t2 = T2 / N. The acceleration time t1 is taken to be much larger than t3 to ensure that no additional stress accumulation occurs in the weld microstructure during acceleration.

[0033] The above embodiments are provided to further describe the present invention in more detail with reference to the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention, and do not constitute a limitation on the specific implementation of the present invention. Within the scope of the claims of the present invention, improvements or equivalent substitutions to the technical methods and steps involved in the present invention, especially combinations of various embodiments without constituting a conflict in principle or operation, all fall within the protection scope of the present invention.

Claims

1. A method for manufacturing an aero-engine rotor, comprising a bladed disk friction welding step, characterized in that, The manufacturing method further includes a rotational stress relief step, which is performed on the original equipment after the bladed disk friction welding step is completed, and is executed when the welded aero-engine rotor cools to 200°C-350°C. In the rotational stress relief step, the rotational load spectrum is a cyclic trapezoidal spectrum, which includes a variable speed stage and a uniform speed stage. The rotational residual stress elimination step eliminates circumferential residual stress through the variable speed stage and eliminates radial residual stress through the uniform speed stage. The method for calculating the rotational load spectrum is as follows: S1. Determine the performance parameters of the aero-engine rotor metal material at the processing temperature according to the metal properties handbook; S2. Based on the dimensions of the aero-engine rotor and the welding parameters, perform simulation calculations to determine the numerical range of radial and circumferential residual stresses in the welding area; S3. Based on the rotor dimensions, calculate the rotational speed at which the radial equivalent stress can eliminate the radial residual stress; S4. Based on the rotor dimensions, calculate the angular acceleration at which the circumferential equivalent stress can eliminate the circumferential residual stress; S5. Based on the values ​​calculated in S3 and S4, and the residual stress distribution obtained from simulation calculations, determine the time of the variable speed stage and the uniform speed stage in each loading cycle, as well as the total loading time.

2. The method for manufacturing an aero-engine rotor according to claim 1, characterized in that, The speed change phase includes an acceleration phase for eliminating circumferential residual stress and a deceleration phase with low angular acceleration.

3. The method for manufacturing an aero-engine rotor according to claim 1, characterized in that, The speed change phase includes an acceleration phase with low angular acceleration and a deceleration phase for eliminating circumferential residual stress.

4. The method for manufacturing an aero-engine rotor according to any one of claims 1 to 3, characterized in that, The bladed disk friction welding step uses inertial friction welding.

5. The method for manufacturing an aero-engine rotor according to claim 4, characterized in that, In the friction welding step, the rotating end rotates at a speed of 300 rpm to 600 rpm, and the moment of inertia is 1000 kg·m. 2 -5000 kg·m 2 The pressure during the upsetting stage is 100MPa-500MPa.

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