Method for strengthening compressor blades of gas turbine engine

Abstract

FIELD: gas turbine engine.SUBSTANCE: method for strengthening compressor blades of a gas turbine engine.Shot-blast hardening of the blade profile is carried out using microbeads with a diameter of 0.2-0.4 mm. Subsequent vibration machining of the blade profile is performed in an abrasive environment. EFFECT: increase of the fatigue strength of the compressor blades while ensuring the required level of blade profile surface roughness.1 cl, 1 dwg

Description

[0001] This invention relates to aircraft engine manufacturing and gas turbine engines (GTEs), specifically to gas turbine engine compressor blades. The operating conditions of GTE compressor blades are associated with prolonged exposure to static and dynamic stresses. Ensuring the cyclic durability of blades is a key challenge in gas turbine engine design. One solution is to increase the blade fatigue life by surface hardening the aerodynamic profile. At the same time, it is important to ensure a high-grade blade profile surface finish, particularly for high-pressure compressor blades, which is extremely difficult to achieve after profile hardening.

[0002] In the practice of hardening compressor blades in gas turbine engines, a method of ultrasonic hardening of the blade profile with balls (RU 2743500 C1) is known, where plastic deformation of the surface is carried out by the movement and collision of balls with the blade being processed in the working chamber due to the excitation of vibrations by an ultrasonic generator.

[0003] The disadvantages of this hardening method include: the inability to impart a high level of kinetic energy to the balls due to the limitations of the ultrasonic generator and the limited size of the working chamber for processing large batches of blades. Insufficient hardening intensity will prevent the blades from achieving the required increase in fatigue strength, making additional hardening impractical and increasing manufacturing labor intensity.

[0004] The closest technical solution to the claimed invention is the method for processing parts (Patent RU 2 449 878, IPC: B24C1 / 00; B24C11 / 00, published 10.05.2012), adopted as a prototype, where the hardening treatment is carried out with a mixture of balls with a diameter of 0.5 to 5 mm and microballs with a diameter of 0.02 to 0.10 mm.

[0005] The disadvantages of the known hardening method used as a prototype include the inevitable deterioration of the surface quality after processing, as even small-diameter microspheres leave marks on the surface that are significantly deeper than the required roughness of the compressor blade profile. This, in turn, negatively impacts airflow around the blade and leads to a deterioration in the compressor's overall performance.

[0006] The technical problem, the solution of which is provided by the implementation of the proposed invention, and which cannot be provided by using the prototype, is the impossibility of maintaining the required roughness of the blade profile surface after intensive shot-peening.

[0007] The technical objective of the claimed invention is to ensure a high-grade blade profile surface finish after hardening, combined with high hardening intensity. Fulfilling these conditions allows for the compressor's aerodynamic parameters to be maintained and the blades' fatigue strength to be increased.

[0008] The technical problem is solved by the fact that during shot blasting hardening of compressor blades, according to the invention, shot blasting of the blade profile is performed with microballs with a diameter of 0.2...0.4 mm, which have the least effect on the deterioration of roughness, and subsequent vibration processing of the blade profile in an environment of abrasive bodies, restoring the required class of profile surface purity.

[0009] In addition, according to the invention, subsequent vibration processing with free movement of the blades in the environment of abrasive bodies is used.

[0010] In addition, according to the invention, subsequent vibration processing is used with the blades being secured in the device by the shank.

[0011] In addition, according to the invention, dry shot peening can be replaced by hydro-shot peening in suspension.

[0012] In addition, according to the invention, shot peening can be performed with ceramic or glass balls.

[0013] Figure 1 shows a diagram of the distribution of residual stresses along the depth of the compressor blade profile before and after applying the proposed strengthening method.

[0014] The proposed method for hardening blades is carried out as follows: shot blasting of the blade profile is performed, after which vibration treatment is carried out, which restores the required roughness of the profile surface.

[0015] Compressor blades were manufactured from VT8M-1 titanium alloy and EP718-ID heat-resistant alloy using the technical solution described above. Before shot peening, the maximum Ra roughness of the serial blades' profile surface was 0.5 μm. After shot peening, the Ra roughness decreased to a maximum of 0.9 μm, which does not meet the profile surface cleanliness requirements. Subsequent vibration treatment with abrasive media improved the Ra roughness to the required value of 0.5 μm. High compressive residual stresses of up to minus 60 kgf / mm were achieved. 2 with a depth of up to 0.05 mm. Using this method of strengthening the blades, the fatigue limit of the blades was increased by 20% to 50%, as evidenced by the characteristic distribution diagram of residual stresses across the depth of the compressor blade profile in Figure 1.

[0016] Compressor blades with the proposed strengthening method have successfully passed experimental tests and are currently being implemented in compressors of advanced aircraft engines.

[0017] Thus, the implementation of the proposed invention with the above-mentioned distinctive features allows for a high level of fatigue strength of the compressor blades in combination with maintaining the required high class of surface cleanliness of the gas turbine engine compressor profile.

Claims

1. A method for hardening compressor blades of a gas turbine engine, including shot-blasting hardening of the blade profile, characterized in that the shot-blasting hardening of the blade profile is performed with microballs with a diameter of 0.2-0.4 mm and subsequent vibration processing of the blade profile is performed in a medium of abrasive bodies.

2. The method according to paragraph 1, characterized in that the subsequent vibration processing of the blade profile is performed with free movement of the blade in the environment of abrasive bodies.

3. The method according to paragraph 1, characterized in that the subsequent vibration processing of the blade profile is performed by securing the blade in the device by its root.

4. The method according to paragraph 1, characterized in that shot-blasting hardening of the profile is performed by hydro-shot-blasting hardening in suspension.

5. The method according to paragraph 1, characterized in that shot-blasting hardening of the profile is performed with ceramic or glass balls.

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