Laser processing method for coupling laser cleaning and laser annealing

Abstract

The invention provides a laser processing method for coupling laser cleaning and laser annealing, which solves the problems that the stress distribution on the cleaning surface is not uniform due to the traditional laser cleaning, and the mechanical property of a part is seriously influenced by residual tensile stress induced after cleaning. Comprising a laser cleaning processing technical scheme, a laser annealing processing technical scheme and a laser cleaning and laser annealing coupling technical scheme. Laser equipment with double light sources is built, a laser cleaning head is arranged at the front section, laser cleaning is firstly carried out, laser annealing of a corresponding area is carried out, and cooperative coupling automatic machining of the two working procedures is achieved. The method has the advantages that the problems that after laser cleaning, surface residual stress distribution is not uniform, and residual tensile stress exists are solved. Production procedures are simplified, and multi-procedure turnover time consumption is saved. Meanwhile, according to the device and the method, adaptive parameter setting is designed for different materials, the matching area and the time sequence of laser cleaning and laser annealing are adjusted, and heat input is strictly controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engines, in particular to a laser processing method coupling laser cleaning and laser annealing. BACKGROUND

[0002] Laser cleaning is an important method for removing pollutants on the surface of metal, which uses laser to directly irradiate and remove the adherents. After the laser is absorbed by the adherents, a large amount of absorption forms a sharply expanding plasma vibration, thereby forcing the substrate and the adherents to separate. Domestic and foreign scholars have made a lot of researches on laser cleaning, and generally believe that ablation and rapid thermal effect are the main mechanisms for removing pollutants. However, the thermal effect process is extremely easy to cause stress changes on the surface of metal, and generate a great amount of residual tensile stress, which affects the service performance of the parts. Therefore, a device and a process method coupling laser cleaning and laser annealing are proposed. Laser annealing can irradiate high-energy-density laser in a very small range in a very short time, so as to reconstruct the surface tissue of the material sample, fully and uniformly distribute the stress, and improve the mechanical properties. SUMMARY

[0003] The purpose of the present application is to remove the pollutants on the surface of material by laser cleaning, and to make up for the surface residual stress disorder caused by laser cleaning by laser annealing, so as to obtain a clean, low-stress and high-performance surface. Moreover, the two light sources of laser cleaning and laser annealing are coupled into one device, so as to reduce the processing procedures and improve the processing efficiency.

[0004] The present application provides a laser cleaning and laser annealing process coupling method mainly aiming at the high-performance laser cleaning demand of aero-engines, so as to solve the problems of uneven stress distribution on the cleaning surface caused by traditional laser cleaning, and the serious influence of residual tensile stress induced after cleaning on the mechanical properties of parts.

[0005] Laser cleaning processing technical scheme: In the laser cleaning process, a nanosecond laser is used as the energy source of laser cleaning, and the energy input of laser cleaning is controlled by adjusting the laser power, repetition frequency and scanning speed, so as to remove the pollutants by gasification and reduce the damage to the substrate.

[0006] For parts with complex structure or unknown model, a three-dimensional scanning device is first used to scan the parts to be cleaned, so as to form a three-dimensional model and establish the positional relationship between the parts and the cleaning device.

[0007] Main process parameter range: Laser power: 5-20 W; Scanning speed: 500-1500 mm / s; Frequency: 40-270 kHz; Laser incidence angle θ: 0-10°; Processing times: 1-5 times; Defocus amount: -0.5-0.5 mm; Laser annealing processing technical solution: In the laser annealing process, a carbon dioxide laser is used as an energy source, and the annealing depth and annealing temperature are controlled by controlling the laser power, scanning speed and other parameters, and argon is filled as necessary to protect the final surface from oxidation and improve the performance of the part.

[0008] Main process parameter range: Laser power: 200-1000W; Scanning speed: 100-500 mm / s; Laser incidence angle θ: 10-45°; Processing times: 1-5 times; Defocus amount: -0.5-0.5 mm; Laser cleaning and laser annealing coupling technical solution The surface of the part is divided into multiple regions, the number of laser cleaning spots in a single region is controlled, and the residence time after laser cleaning is adjusted, and then the laser annealing process is implemented.

[0009] The technical key of this process method is to build a laser device with double light sources, the laser cleaning head is placed in the front section, first laser cleaning is implemented, after n spot laser cleaning, the interval time t is controlled, and then the corresponding region laser annealing is implemented, realizing the automatic processing of the two processes. Coupling, and n and t are adjusted according to the actual situation. Effectively avoid the problem that the surface heat input of traditional laser combined processing process may be too large, and the surface quality cannot be accurately controlled.

[0010] Advantages of the present application: The present application mainly proposes a new laser processing method of laser cleaning and laser annealing coupling, which solves the problem of uneven distribution of residual stress on the surface after laser cleaning, and the existence of residual tensile stress. While solving the problem of disorder of the stress on the cleaned surface, the production process is simplified, and the multi-process turnaround time is saved. At the same time, the device and method adjust the matching area and time sequence of laser cleaning and laser annealing according to the adaptive parameter settings of different materials, and strictly control the heat input. BRIEF DESCRIPTION OF DRAWINGS

[0011] The present application will be further described in detail below in combination with the drawings and embodiments: Figure 1 Laser cleaning-laser annealing coupling equipment schematic diagram; Figure 2 TC4 surface black contaminants; Figure 3The surface photo of TC4 after laser cleaning and laser annealing coupling; Figure 4 The black contaminants on the surface of 0Cr18Ni9; Figure 5 The surface photo of 0Cr18Ni9 after laser cleaning and laser annealing coupling; In the figure, 1 is a laser cleaning head, 2 is a part, 3 is a laser annealing head, and 4 is a rotary table. DETAILED DESCRIPTION

[0012] Example 1: TC4 titanium alloy laser cleaning and laser annealing coupling method (1) Reference Figure 1 The part is clamped to the equipment rotary table, a three-dimensional scanner is used to scan the part to obtain the actual model of the part, and the relative position relationship between the part and the equipment is established.

[0013] (2) Set the laser cleaning parameters (including laser power 20W, scanning speed 1200mm / s, repetition frequency 270KHz, laser incidence angle 0°, processing times 1, and defocusing amount 0mm) in the laser cleaning software.

[0014] (3) Plan the laser cleaning path, divide the laser cleaning area into several areas for partition processing, set the number of single area single laser cleaning spots to 20, and decompose the processing path and code; (4) Set the laser annealing parameters (including laser power 300W, scanning speed 300mm / s, laser incidence angle 30°, processing times 2, and defocusing amount -0.3mm).

[0015] (5) Process implementation: set the interval time between laser cleaning and laser annealing to 20ms, the laser cleaning head first implements laser cleaning on the part, after 20 spots in a single area, the part position changes with the rotary table, and after waiting for 20ms, the laser annealing head performs laser annealing on the part. Partition the cleaning and annealing of the part to finally realize the laser processing of the entire part.

[0016] (6) Figure 3 The cleaning effect of TC4 material under the present embodiment process is shown in the figure, the original black contaminants on the surface are completely removed after laser cleaning and laser annealing coupling, Figure 2 and the surface residual stress is tested to be 10MPa, which meets the high-performance surface quality requirements.

[0017] Example 2: 0Cr18Ni9 stainless steel laser cleaning and laser annealing coupling method (1) Reference Figure 1The part is clamped to the equipment turntable, the part is scanned using a three-dimensional scanner, an actual model of the part is obtained, and a relative position relationship between the part and the equipment is established.

[0018] (2) Set the laser cleaning parameters (including laser power 20W, scanning speed 1000mm / s, repetition frequency 120KHz, laser incidence angle 0°, processing times 1, and defocusing amount 0mm) in the laser cleaning software.

[0019] (3) Plan the laser cleaning path, decompose the laser cleaning area into several areas for partition processing, set the number of single area single laser cleaning spots to 50, and form the processing path and code by decomposition; (4) Set the laser annealing parameters (including laser power 500W, scanning speed 400mm / s, laser incidence angle 20°, processing times 1, and defocusing amount-0.5mm).

[0020] (5) Process implementation: set the interval time between laser cleaning and laser annealing to 5ms, the laser cleaning head first implements laser cleaning on the part, after 50 spots in a single area are circulated, then the position of the part changes with the turntable, and after waiting for 5ms, the laser annealing head performs laser annealing on the part. The cleaning and annealing of the part are carried out in partitions, and finally the laser processing of the whole part is realized.

[0021] (6) Figure 5 The cleaning effect of 0Cr18Ni9 material under the process is shown in the figure. Figure 4 The original black contaminants on the surface are completely removed after coupling of laser cleaning and laser annealing, and the surface residual stress is tested to be 5MPa, which meets the high-performance surface quality requirements.

[0022] The remaining matters of the present application are known technologies.

[0023] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of laser processing coupled with laser cleaning and laser annealing, characterized by: The laser cleaning and laser annealing coupled laser processing method is aimed at the high-performance laser cleaning demand of an aero-engine. Through the laser cleaning and laser annealing process coupling method, the problem of uneven stress distribution on the cleaned surface caused by traditional laser cleaning and the problem of serious residual tensile stress induced after cleaning which seriously affects the mechanical properties of the part are solved. Laser cleaning processing technical scheme: In the laser cleaning process, a nanosecond laser is used as the energy source of laser cleaning. By adjusting the laser power, repetition frequency and scanning speed to control the energy input of laser cleaning, the pollutants are gasified and removed while the damage to the substrate is reduced. For parts with complex structure or unknown model, first use a three-dimensional scanning device to scan the parts to be cleaned to form a three-dimensional model, and establish the position relationship between the parts and the cleaning equipment. Process parameter range: Laser power: 5-20 W; Scanning speed: 500~1500 mm / s; Frequency: 40~270 kHz; Laser incidence angle θ: 0~10°; Processing times: 1~5 times; Defocusing amount: -0.5~0.5 mm; Laser annealing processing technical scheme: In the laser annealing process, a carbon dioxide laser is used as the energy source. By controlling the laser power, scanning speed and other parameters to control the annealing depth and annealing temperature, argon gas is filled as needed to protect the final surface from oxidation and improve the performance of the part. Process parameter range: Laser power: 200-1000 W; Scanning speed: 100~500 mm / s; Laser incidence angle θ: 10~45°; Processing times: 1~5 times; Defocusing amount: -0.5~0.5 mm; Laser cleaning and laser annealing coupling technical scheme: The surface of the part is divided into multiple regions, the number of laser cleaning spots in a single region is controlled, and the dwell time after laser cleaning is adjusted, and then the laser annealing process is implemented.

2. The laser processing method of claim 1, wherein: Build a laser device with double light sources, place the laser cleaning head in the front section, first implement laser cleaning, control the interval time t after n spot laser cleaning, and immediately implement laser annealing in the corresponding area to realize the automatic processing of the two processes. Moreover, n and t are adjusted according to actual conditions; effectively avoid the problem of excessive surface heat input that may exist in traditional laser combined processing technology, which cannot accurately control the surface quality.

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