Method for improving wear resistance of vibration reduction boss through micro-scale laser shock peening

Abstract

The invention belongs to the technical field of laser strengthening, and discloses a method for improving the wear resistance of a vibration reduction boss through micro-scale laser shock peening, and the method comprises the following steps: carrying out preprocessing treatment on a to-be-strengthened surface of the vibration reduction boss of a compressor blade; micro-scale laser surface impact strengthening is conducted on the to-be-strengthened surface of the blade vibration reduction boss obtained after preprocessing treatment, and the strengthened surface of the blade vibration reduction boss is obtained; and femtosecond laser shock peening is conducted on the strengthened surface of the blade vibration reduction boss, and the blade vibration reduction boss subjected to compound peening is obtained. According to the method, the abrasion resistance of the surface of the blade vibration reduction boss can be remarkably improved, meanwhile, the surface of the blade vibration reduction boss has low roughness, and the method has the technical advantages of being high in machining precision, uniform in distribution of an introduced residual stress field, high in machining efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of laser strengthening, and in particular relates to a method for improving the wear resistance of a vibration-damping boss by micro-scale laser shock strengthening. Background Art

[0002] Microscale laser shock peening surface modification technology uses high-power density laser to irradiate the surface of the material, inducing plasma shock waves to act on the material, causing it to undergo severe plastic deformation and introduce a large residual compressive stress layer and a work hardening layer. At the same time, it can refine the surface grains of the material and introduce gradient dislocation structures. No absorption protective layer is required during the process. At the same time, due to its small spot diameter, high-precision selective strengthening can be achieved. The vibration-damping bosses between the compressor blades of modern aircraft engines often come into contact and rub during service. Under long-term operation, microcracks or even cracks visible to the naked eye often appear on the wear surface, which seriously endangers the service safety of aircraft engines.

[0003] Therefore, there is an urgent need for a high-performance, high-precision surface treatment technology that can not only improve the wear resistance of the compressor blade damping boss, but also extend its service life after wear. Summary of the invention

[0004] The purpose of the present invention is to provide a method for improving the wear resistance of vibration-damping bosses by micro-scale laser shock strengthening, so as to solve the problem that the wear resistance of vibration-damping bosses of existing compressor blades needs to be improved.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a method for improving the wear resistance of a vibration-damping boss by micro-scale laser shock strengthening, the method comprising: Pre-processing the surface to be strengthened of the vibration reduction boss of the compressor blade; Performing micro-scale laser surface impact strengthening on the surface to be strengthened of the blade vibration-damping boss after pre-processing to obtain the strengthened surface of the blade vibration-damping boss; The reinforced surface of the blade vibration-damping boss is subjected to femtosecond laser shock strengthening to obtain a composite-strengthened blade vibration-damping boss.

[0006] Preferably, the method further comprises: performing post-processing on the composite reinforced blade vibration-damping boss, wherein the post-processing at least comprises: a cleaning process and a drying process; The post-processing of the composite reinforced blade vibration reduction boss comprises: Using the first cleaning medium to clean the composite reinforced blade vibration reduction boss; After the cleaning time of the blade vibration-damping boss reaches a first preset time, the composite-strengthened blade vibration-damping boss is dried.

[0007] Preferably, the first cleaning medium is anhydrous ethanol, and the first preset time is greater than or equal to 5 minutes.

[0008] Preferably, the surface to be strengthened of the compressor blade vibration reduction boss is pre-processed, including: The surface to be strengthened of the compressor blade vibration reduction boss is ground by sandpaper, and then the ground surface to be strengthened is polished; Using a second cleaning medium to clean the polished surface to be strengthened of the compressor blade vibration reduction boss; After the cleaning time of the surface to be strengthened of the compressor blade vibration-damping boss reaches a second preset time, the surface to be strengthened of the compressor blade vibration-damping boss is dried.

[0009] Preferably, the second cleaning medium is anhydrous ethanol, and the second preset time is greater than or equal to 5 minutes.

[0010] Preferably, the particle size of the sandpaper is 600-2000 mesh.

[0011] Preferably, micro-scale laser surface impact strengthening is performed on the surface to be strengthened of the pre-processed blade vibration-damping boss to obtain the strengthened surface of the blade vibration-damping boss, including: The pre-processed blade vibration-damping boss is clamped and installed using a fixture of preset specifications; Fixing a fixture with a pre-processed blade vibration reduction boss on a flexible optical fiber kilohertz high repetition rate laser processing platform; The surface to be strengthened of the blade vibration-damping boss after pre-processing is scanned and impacted with the set first laser parameters and within a preset temperature range until the surface to be strengthened completes a complete microscale laser strengthening to obtain the strengthened surface of the blade vibration-damping boss; wherein the first laser parameters include at least: laser energy, overlap rate, number of laser irradiations, frequency, laser spot diameter and spot shape.

[0012] Preferably, the preset temperature range is 20°C~30°C.

[0013] Preferably, femtosecond laser shock strengthening is performed on the strengthened surface of the blade vibration-damping boss to obtain a composite-strengthened blade vibration-damping boss, including: The strengthened surface of the blade vibration-damping boss is placed on a femtosecond laser shock peening platform, and the strengthened surface of the blade vibration-damping boss is subjected to femtosecond laser shock peening treatment with a set second laser parameter to obtain a compositely strengthened blade vibration-damping boss.

[0014] Beneficial effects: 1. The present invention can significantly improve the wear resistance of the surface of the blade vibration damping boss by successively performing microscale laser surface impact strengthening and femtosecond laser impact strengthening on the surface to be strengthened of the blade vibration damping boss, and at the same time, the surface of the blade vibration damping boss also has a lower roughness; 2. The method of improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening of the present invention also has the technical advantages of high processing accuracy, uniform distribution of the introduced residual stress field, and high processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a flow chart of a method for improving the wear resistance of a vibration-damping boss by micro-scale laser shock strengthening provided by one embodiment of the present invention; Figure 2 It is a schematic diagram comparing the three-dimensional morphology and roughness of the vibration-damping boss surface after different parameter processing; Figure 3 It is a schematic diagram of the friction coefficient curve of the vibration-damping boss surface after different parameter processing; Figure 4 It is a schematic diagram of the cross-sectional area of ​​the wear scar on the surface of the vibration-damping boss after different parameter processing. DETAILED DESCRIPTION

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0017] Embodiment 1 Figure 1 FIG. 1 is a flow chart of a method for improving the wear resistance of a vibration-damping boss by micro-scale laser shock strengthening provided by an embodiment of the present invention. Figure 1 As shown, this embodiment provides a method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening, and the method includes: Step S10: pre-processing the surface to be strengthened of the compressor blade vibration-damping boss.

[0018] In this embodiment, the pre-processing treatment includes: grinding treatment, cleaning treatment and drying treatment, and the pre-processing treatment of the surface to be strengthened of the compressor blade damping boss includes the following steps: Firstly, the surface to be strengthened of the compressor blade vibration reduction boss is ground with sandpaper, and then the ground surface to be strengthened is polished; In this embodiment, the material of the surface to be strengthened of the compressor blade vibration damping boss is 40Cr (standard steel grade), the specimen size of the compressor blade vibration damping boss is 10mm*10mm*3mm, and the area of ​​the surface to be strengthened is 10mm*10mm.

[0019] When polishing, the particle size of sandpaper is 600-2000 mesh. Use 600 mesh, 800 mesh, 1000 mesh, 1200 mesh, 1400 mesh, 1600 mesh, 1800 mesh, and 2000 mesh sandpaper to polish the surface to be strengthened in turn to remove the oxide layer and impurities; that is, first use 600 mesh sandpaper to polish the surface to be strengthened for the first time, and then use 800 mesh sandpaper to polish the surface to be strengthened for the second time, each time increasing by 200 grit, until the final time using 2000 mesh sandpaper to polish the surface to be strengthened, a total of 8 times of polishing.

[0020] After the grinding of the surface to be strengthened is completed, mechanical polishing is performed in a polishing machine using a silica polishing liquid, and the polishing direction is perpendicular to the sandpaper grinding direction to remove surface scratches; then the surface roughness is measured to determine whether the average surface roughness Sa after polishing is 0.085 μm. If the roughness is not reached, the surface to be strengthened is polished again until the average surface roughness Sa after polishing is 0.085 μm.

[0021] Next, the polished surface to be strengthened of the compressor blade damping boss is cleaned with a second cleaning medium; wherein the second cleaning medium is anhydrous ethanol, and the second preset time is greater than or equal to 5 minutes.

[0022] In this embodiment, an ultrasonic cleaning machine is used for cleaning. Anhydrous ethanol is first added into the ultrasonic cleaning machine, and then the polished compressor blade damping boss is placed into the ultrasonic cleaning machine. The ultrasonic cleaning machine is started, and anhydrous ethanol is used as a cleaning medium to clean the surface of the compressor blade damping boss. The cleaning time is more than 5 minutes, and all wear particles or rust can be removed.

[0023] Finally, after the cleaning time of the surface to be strengthened of the compressor blade vibration-damping boss reaches a second preset time, the surface to be strengthened of the compressor blade vibration-damping boss is dried.

[0024] After taking out the sample from the ultrasonic cleaning machine, it is placed in flowing compressed hot air until the surface is completely dry. At this time, the pre-processing of the surface to be strengthened of the compressor blade damping boss is completed.

[0025] Step S20: performing micro-scale laser surface impact strengthening on the surface to be strengthened of the blade vibration-damping boss after pre-processing to obtain a strengthened surface of the blade vibration-damping boss.

[0026] In this embodiment, the specific operation steps of performing micro-scale laser surface impact strengthening on the surface to be strengthened of the pre-processed blade vibration-damping boss are as follows: Firstly, the pre-processed blade vibration-damping boss is clamped and installed using a fixture of preset specifications.

[0027] Next, the fixture with the pre-processed blade vibration reduction boss is fixed on a flexible optical fiber kilohertz high repetition rate laser processing platform, and the flexible optical fiber kilohertz high repetition rate laser processing platform adopts a YSM2000-C30A laser shock strengthening processing platform.

[0028] Finally, the surface to be strengthened of the blade vibration-damping boss after pre-processing is scanned and impacted with the set first laser parameters and within a preset temperature range until the surface to be strengthened completes a complete microscale laser strengthening to obtain the strengthened surface of the blade vibration-damping boss; wherein the first laser parameters include at least: laser energy, overlap rate, number of laser irradiations, frequency, laser spot diameter and spot shape.

[0029] For 40Cr material, the preset first laser parameters are: laser energy 50mj / 150mj / 200mj, spot diameter 0.5mm, spot overlap rate 50%, and impact number 1, and then the processing starts according to the planned path until the predetermined strengthening area is covered.

[0030] In this embodiment, the preset temperature range is 20°C to 30°C, and the temperature of the scanning impact is preferably 25°C.

[0031] Step S30: performing femtosecond laser shock strengthening on the strengthened surface of the blade vibration-damping boss to obtain a composite-strengthened blade vibration-damping boss.

[0032] In this embodiment, the operating steps of performing femtosecond laser shock strengthening on the reinforced surface of the blade vibration damping boss are as follows: placing the reinforced surface of the blade vibration damping boss on a femtosecond laser shock strengthening platform, and performing femtosecond laser shock strengthening on the reinforced surface of the blade vibration damping boss with set second laser parameters to obtain a compositely strengthened blade vibration damping boss; wherein the second laser parameters include at least: laser energy, overlap rate, number of laser irradiations, frequency, laser spot diameter and spot shape, etc.

[0033] In this embodiment, the strengthened surface after the treatment in step S20 is placed on a femtosecond processing platform, and appropriate laser parameters are selected for femtosecond laser shock strengthening treatment to regulate the surface structure and morphology, remove the ablation pits and remelted layer left after the S2 treatment, and reduce the surface roughness.

[0034] As a further optimization of this embodiment, the method further includes: performing post-processing on the composite reinforced blade vibration-damping boss, wherein the post-processing at least includes: cleaning and drying; The post-processing of the composite reinforced blade vibration reduction boss comprises: First, the composite reinforced blade vibration damping boss is cleaned with a first cleaning medium; wherein the first cleaning medium is anhydrous ethanol; specifically, the composite reinforced blade vibration damping boss is placed in an ultrasonic cleaning machine and cleaned with anhydrous ethanol medium for more than 5 minutes.

[0035] Then, after the cleaning time of the blade vibration damping boss reaches the first preset time, the composite reinforced blade vibration damping boss is dried; that is, the composite reinforced blade vibration damping boss is taken out from the ultrasonic cleaning machine and placed in flowing compressed hot air until the surface is completely dry.

[0036] The present invention mainly uses low-energy pulse laser to introduce a work hardening layer and a residual compressive stress layer on the blade wear surface. On the one hand, the work hardening layer can improve the wear resistance of the boss itself, and on the other hand, the residual compressive stress layer can inhibit the further expansion of cracks after the boss is worn, thereby increasing its service life. Therefore, the present invention has the technical advantages of high processing accuracy, uniform distribution of the introduced residual stress field, and high processing efficiency.

[0037] Compared with other surface treatment technologies, such as conventional nanosecond laser shock strengthening technology, the microscale laser shock strengthening technology of the present invention has the following advantages: 1. The spot diameter is small, and high-precision selective strengthening can be performed on components with complex surface morphology; 2. There is no absorption protective layer, which can save time and economic costs; 3. The processing efficiency is high, and a high-repetition-rate pulse laser is used, with the fastest frequency reaching 400Hz; 4. The depth of the affected layer is shallow, and thin-walled components can be processed, and the deformation of the components after processing is small, and stress concentration will not be caused in other positions. The technical advantages of this technology are very suitable for the wear-resistant surface treatment of the compressor vibration damping boss, which increases the service safety and service life of the blades and saves a lot of economic and time costs; 5. The secondary treatment of the femtosecond laser eliminates the adverse effects of the remelting layer and the ablation pit, and further improves and optimizes the hardness and residual stress of the blade vibration damping boss.

[0038] Figure 2-Figure 4 The schematic diagram of the three-dimensional morphology, profile data and friction coefficient of the samples after different energy treatments is given. Figure 2 In, Sa is the roughness; Figure 3In , COF is the friction coefficient, Time is the processing time, Substrate is the substrate, 1 is the sample numbered 1, 2 is the sample numbered 2, and 3 is the sample numbered 3; Figure 4 In the figure, Grinding section area is the cross-sectional area of ​​the wear scar.

[0039] After femtosecond laser treatment, the samples treated with 50mj, 150mj and 200mj are respectively for samples No. 1, 2 and 3. Compared with the substrate, the surface roughness of the samples is significantly reduced after femtosecond laser treatment to adjust the surface structure and morphology. At the same time, it can be seen from the wear scar interface area that the wear resistance of the treated specimens is significantly improved.

[0040] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0041] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0042] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for improving the wear resistance of a vibration-damping boss by micro-scale laser shock strengthening, characterized in that: The method comprises: Pre-processing the surface to be strengthened of the vibration reduction boss of the compressor blade; Performing micro-scale laser surface impact strengthening on the surface to be strengthened of the blade vibration-damping boss after pre-processing to obtain the strengthened surface of the blade vibration-damping boss; The reinforced surface of the blade vibration-damping boss is subjected to femtosecond laser shock strengthening to obtain a composite-strengthened blade vibration-damping boss.

2. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock peening according to claim 1 is characterized in that: The method further comprises: performing post-processing on the composite reinforced blade vibration-damping boss, wherein the post-processing at least comprises: cleaning and drying; The post-processing of the composite reinforced blade vibration reduction boss comprises: Using the first cleaning medium to clean the composite reinforced blade vibration reduction boss; After the cleaning time of the blade vibration-damping boss reaches a first preset time, the composite-strengthened blade vibration-damping boss is dried.

3. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening according to claim 2 is characterized in that: The first cleaning medium is anhydrous ethanol, and the first preset time is greater than or equal to 5 minutes.

4. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening according to claim 1 is characterized in that: Pre-processing of the surface to be strengthened of the compressor blade damping boss includes: The surface to be strengthened of the compressor blade vibration reduction boss is ground by sandpaper, and then the ground surface to be strengthened is polished; Using a second cleaning medium to clean the polished surface to be strengthened of the compressor blade vibration reduction boss; After the cleaning time of the surface to be strengthened of the compressor blade vibration-damping boss reaches a second preset time, the surface to be strengthened of the compressor blade vibration-damping boss is dried.

5. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening according to claim 4 is characterized in that: The second cleaning medium is anhydrous ethanol, and the second preset time is greater than or equal to 5 minutes.

6. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening according to claim 4 is characterized in that: The particle size of the sandpaper is 600 mesh to 2000 mesh.

7. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock peening according to claim 1 is characterized in that: The surface to be strengthened of the pre-processed blade vibration reduction boss is subjected to micro-scale laser surface impact strengthening to obtain the strengthened surface of the blade vibration reduction boss, including: The pre-processed blade vibration-damping boss is clamped and installed using a fixture of preset specifications; Fixing a fixture with the pre-processed blade vibration reduction boss on a flexible optical fiber kilohertz high repetition rate laser processing platform; The surface to be strengthened of the blade vibration-damping boss after pre-processing is scanned and impacted with the set first laser parameters and within a preset temperature range until the surface to be strengthened completes a complete microscale laser strengthening to obtain the strengthened surface of the blade vibration-damping boss; wherein the first laser parameters include at least: laser energy, overlap rate, number of laser irradiations, frequency, laser spot diameter and spot shape.

8. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock strengthening according to claim 7 is characterized in that: The preset temperature range is 20°C to 30°C.

9. The method for improving the wear resistance of the vibration-damping boss by micro-scale laser shock peening according to claim 1, characterized in that: The reinforced surface of the blade vibration reduction boss is subjected to femtosecond laser shock strengthening to obtain a compositely strengthened blade vibration reduction boss, including: The strengthened surface of the blade vibration-damping boss is placed on a femtosecond laser shock peening platform, and the strengthened surface of the blade vibration-damping boss is subjected to femtosecond laser shock peening treatment with a set second laser parameter to obtain a compositely strengthened blade vibration-damping boss.

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