A non-destructive cleaning device and method based on continuous-pulse laser

Abstract

A non-destructive cleaning device and method based on continuous-pulse lasers controls the degree of damage to the surface being cleaned during the laser cleaning process by adjusting the scanning distance between the continuous and pulsed laser beams. The device and method are characterized by comprising a fixed continuous laser optical path, a variable-distance pulsed laser optical path, and a high-performance CCD camera. The continuous laser optical path includes a continuous laser collimator, a reflector, a galvanometer, and a field lens; the pulsed laser optical path includes a pulsed laser collimator, a galvanometer, and a field lens. The pulsed laser scanning system, including the galvanometer and field lens, is movable, enabling control of the distance between the pulsed laser and the continuous laser during scanning. The high-performance CCD camera captures images of the workpiece in real time and, by observing the cleaning status of the workpiece surface, adjusts the distance between the two laser beams in real time to achieve non-destructive cleaning. This cleaning method not only offers high cleaning efficiency but also reduces damage to the workpiece, making the cleaning process more controllable.

Description

Technical Field

[0001] The present invention relates to the field of laser cleaning technology, in particular to a laser cleaning technology capable of achieving the purpose of non-destructive cleaning, specifically to a non-destructive cleaning device and method based on continuous-pulse laser. Background Art

[0002] Laser cleaning technology is an efficient and environmentally friendly surface cleaning technique. With the continuous development of laser technology, it has also experienced rapid growth and is increasingly being used to remove rust and paint from metal surfaces in industry. On the one hand, metal surfaces are prone to chemical reactions with surrounding media, corroding and losing their effectiveness, resulting in waste. Many industrial buildings also suffer from severe steel corrosion due to their age. On the other hand, aircraft skins have complex coating systems. To ensure normal service performance, the surface coatings must be stripped and repainted during overhaul. Traditional paint stripping methods are generally prone to serious pollution and are time-consuming. Laser cleaning technology can achieve high-efficiency and high-precision rust and paint removal.

[0003] Traditional cleaning methods using a single pulsed laser beam are ineffective for rust and paint layers. Short-pulse lasers offer high precision but low efficiency, while long-pulse lasers offer high efficiency but low precision. For rust, multiple cleaning cycles are generally required to achieve effective results, resulting in low efficiency. For the complex multi-layer coatings found on aircraft, pulsed lasers require specific parameters to remove the coating layer by layer, resulting in low removal efficiency. Using high-peak-power laser pulses can also easily damage the substrate.

[0004] The main principle of composite laser cleaning is to use the characteristics of continuous laser high thermal effect ablation to quickly remove the thicker paint layer on the surface, perform preliminary cleaning of the paint layer, and then use pulsed laser to remove the remaining paint layer. It is highly efficient and can completely remove the paint layer while protecting the substrate from damage. Summary of the Invention

[0005] The purpose of the present invention is to address the problems of low efficiency, high time cost and difficulty in controlling substrate damage in current technologies, and to provide a non-destructive cleaning device based on continuous and pulsed lasers, which has the ability to control the spacing between the two laser beams, and a corresponding cleaning method.

[0006] One of the technical solutions of the present invention is:

[0007] A non-destructive cleaning device based on continuous-pulse laser, characterized in that it comprises:

[0008] A bracket 1 is used to install a continuous laser cleaning device 2, a pulse laser cleaning device 3, a linear rolling guide 4 and a high-performance CCD camera 5; the continuous laser cleaning device 2 is located before the pulse laser cleaning device 3, and the high-performance CCD camera 5 is installed after the pulse laser cleaning device 3; the slider 8 on the linear rolling guide 4 is fixedly connected to the pulse laser scanning system 33; the position of the slider 8 on the linear rolling guide 4 is achieved by the cooperation of the fixing hole 9.

[0009] A continuous laser cleaning device 2, comprising a continuous laser generator 21, a continuous laser collimator 22 and a continuous laser scanning system 23;

[0010] a pulse laser cleaning device 3, the pulse laser cleaning device 3 comprising a pulse laser generator 31, a pulse laser collimator 32 and a pulse laser scanning system 33;

[0011] A linear rolling guide 4 is provided with a slider 8, which is provided with a fixing hole 9. A pulse laser scanning system 33 is mounted on the slider 4 through the fixing hole 9 and is connected to a retractable lens barrel 34;

[0012] A high-performance CCD camera 5 is installed after the pulse laser cleaning device 3 and is used to capture images of the workpiece surface after cleaning.

[0013] The continuous laser cleaning device 2 includes a continuous laser generator 21, a continuous laser collimator 22, a continuous laser reflecting mirror 23a, a continuous laser galvanometer 23b and a continuous laser field mirror 23c.

[0014] The pulse laser cleaning device 3 includes a pulse laser generator 31 , a pulse laser collimator 32 , a pulse laser galvanometer 33 a , a pulse laser field mirror 33 b and a retractable lens barrel 34 .

[0015] Furthermore, the continuous laser field mirror 23c is an F-θ lens group, and the surface is coated with an anti-reflection film.

[0016] The linear rolling guide rail 4 is used to control the movement of the pulse laser scanning system 33 to adjust the distance between the continuous laser beam and the pulse laser beam.

[0017] Furthermore, the pulse laser scanning system 33 only reciprocates in the horizontal direction when moving. Through the structure of the telescopic lens barrel 34, the distance between the two laser beams can be adjusted by moving the slider 8.

[0018] A further beneficial effect of the above method is that the distance between the two laser beams can be controlled without changing the position of the pulse laser generator 31 .

[0019] After the continuous laser generator 21 is turned on, the power, scanning width and scanning path are adjusted. The light beam passes through the continuous laser reflector 23a to the continuous laser galvanometer 23b, and then passes through the continuous laser field mirror 23c to reach the surface of the cleaning workpiece.

[0020] After the pulse laser generator 31 is turned on, the power and frequency are adjusted, and the scanning format and scanning path are adjusted to be the same as the continuous laser generator 21. The light beam passes through the retractable lens barrel 34 to reach the pulse laser galvanometer 33a, and passes through the pulse laser field lens 33b to reach the surface of the cleaning workpiece.

[0021] Furthermore, the continuous laser is used to clean most of the objects to be removed on the surface; the pulsed laser is used thereafter to clean the remaining objects to be removed on the surface without damaging the surface.

[0022] Furthermore, the high-performance CCD camera is installed behind the pulse laser beam to photograph the surface of the substrate after scanning. The position of the scanning system in the pulse laser cleaning device is adjusted according to the cleaning condition of the substrate surface after cleaning.

[0023] Furthermore, when the continuous laser power and pulsed laser power frequency remain unchanged, the substrate surface cleaning quality improves as the distance between the two laser beams decreases, and complete cleaning can be achieved when a certain distance is reached; if the damage threshold is exceeded, the damage increases as the distance decreases.

[0024] Therefore, the spacing adjustment between the continuous laser beam and the pulsed laser beam is as follows: if the image analysis shows that the proportion of residual objects to be removed on the surface does not meet the cleaning standard, the spacing is reduced; if the image analysis shows that the surface damage exceeds the surface quality requirements, the spacing is increased.

[0025] Furthermore, the distance the pulsed laser scanning system moves each time is determined by the distance between the fixed holes of the linear rolling guide; the range of reciprocating movement depends on the length of the guide and the set slider stroke. Linear rolling guides provide high-precision, high-rigidity, and high-speed motion control, thereby achieving control over sliding distance.

[0026] Combining laser cleaning with nondestructive testing effectively achieves nondestructive laser cleaning. For rust and paint removal, the system can simultaneously detect whether the substrate has been damaged, cracked, or broken due to cleaning, achieving simultaneous cleaning and testing, effectively improving efficiency.

[0027] The second technical solution of the present invention is:

[0028] A cleaning method for a non-destructive cleaning device based on a continuous-pulse laser is characterized by: first, simultaneously turning on a continuous laser and a pulsed laser, and adjusting the power frequency; in the continuous laser optical path, a continuous laser reflector and a continuous laser galvanometer are both fixed at 45 degrees inside a housing; after light is reflected by the reflector, the direction of the beam changes by 90 degrees, and forms a 45-degree angle with the continuous laser galvanometer lens. After entering the continuous laser galvanometer lens, the direction of the beam changes by 90 degrees again and enters the galvanometer lens; a galvanometer motor drives the galvanometer lens to rotate at high speed to scan the workpiece to be cleaned; in the pulse optical path, the pulsed laser galvanometer is fixed at 45 degrees, the pulsed laser beam is incident on the pulsed laser galvanometer lens at 45 degrees, the beam direction changes by 90 degrees, and enters the pulsed laser field mirror;

[0029] Secondly, during cleaning, the continuous laser beam scans the workpiece in sequence and simultaneously after the pulsed laser beam; the high-performance CCD camera takes real-time photos and monitors after the scanning beam;

[0030] When the continuous laser beam reaches the workpiece surface, it achieves relatively uniform cleaning. By controlling the parameters, it can achieve a cleaning level of about 90% of the surface rust without causing damage to the substrate. The workpiece is cleaned by the pulsed laser while maintaining the residual heat from the continuous laser cleaning. By utilizing the residual heat, the pulsed laser can efficiently remove the remaining rust.

[0031] During the cleaning process, a high-performance CCD camera captures images of the workpiece surface in real time, analyzes whether the workpiece surface meets the cleaning requirements, and dynamically adjusts the spacing between the continuous laser and the pulsed laser based on the results; effectively utilizes residual heat to improve the efficiency of pulsed laser cleaning and reduce the degree of damage to the substrate; the sequential action of continuous laser and pulsed laser can produce better cleaning effects than a single pulse laser of the same power and save energy.

[0032] The steps for real-time monitoring using a high-performance CCD camera are as follows:

[0033] 1) Optical imaging: The image of the workpiece being cleaned is imaged onto a CCD photosensitive chip to form a two-dimensional image;

[0034] 2) Signal conversion: The CCD camera converts the image on the photosensitive chip into an electrical signal, which is then amplified and de-noised to obtain a high-quality digital image signal.

[0035] 3) Real-time detection algorithm: Use image processing algorithms to analyze whether impurities or dirt on the workpiece surface have been removed, or detect whether cracks or other damage have appeared on the workpiece surface;

[0036] 4) Result analysis and feedback control: Through analysis and feedback control of monitoring results, precise control and adjustment of cleaning intervals can be achieved to ensure cleaning effect and workpiece quality.

[0037] The beneficial effects of the present invention are:

[0038] 1. The continuous-pulse laser cleaning device described in this invention efficiently removes complex debris from substrate surfaces using both continuous and pulsed laser beams. First, the continuous laser beam provides initial cleaning of the substrate, achieving a thickness removal rate of approximately 80% to 90% without damaging the substrate. Second, the pulsed laser beam, after the continuous laser treatment, utilizes the residual heat from the continuous laser beam to simultaneously and precisely remove residual debris from the underlying substrate for complete cleaning, significantly saving time and costs while effectively preventing damage to the substrate surface.

[0039] 2. The present invention realizes the simultaneous implementation of continuous and pulsed laser two-step cleaning through the design of two optical paths and structures. The scanning system of the pulsed laser optical path is controlled by a slide rail in the horizontal direction. The spacing between the continuous and pulsed dual laser beams can be controlled without changing the input pulse laser device, thereby achieving the purpose of accurately controlling the laser cleaning effect and avoiding damage to the substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of the present invention.

[0041] Figure 2 Schematic diagram of the internal light path of the present invention.

[0042] Figure 3 It is a structural schematic diagram of the linear rolling guide rail of the present invention.

[0043] Figure 4 It is a schematic structural diagram of the continuous laser galvanometer and the pulsed laser galvanometer of the present invention.

[0044] Figure 5 It is a schematic diagram of the cleaning principle of the present invention.

[0045] Appendix: 1-bracket; 2-continuous laser cleaning device; 21-continuous laser generator; 22-continuous laser collimator; 23-continuous laser scanning system; 23a-continuous laser reflector; 23b-continuous laser galvanometer; 23c-continuous laser field mirror; 3-pulsed laser cleaning device; 31-pulsed laser generator; 32-pulsed laser collimator; 33-pulsed laser scanning system; 33a-pulsed laser galvanometer; 33b-pulsed laser field mirror; 34-retractable lens barrel; 4-linear rolling guide; 5-high-performance CCD camera; 6-galvanometer motor; 7-galvanometer lens; 8-slider; 9-fixing hole; 10-continuous laser beam; 11-pulsed laser beam; 12-cleaning workpiece. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] like Figure 1-4 shown.

[0049] A non-destructive cleaning device based on continuous-pulse laser includes a continuous laser cleaning device 2, a continuous laser scanning system 23, a pulsed laser cleaning device 3, a pulsed laser scanning system 33, a retractable lens barrel 34, a linear rolling guide 4, and a high-performance CCD camera 5.

[0050] like Figure 2 As shown, the continuous laser cleaning device includes a continuous laser 21, a continuous laser collimator 22, a continuous laser reflecting mirror 23a, a continuous laser galvanometer 23b, and a continuous laser field mirror 23c.

[0051] In the continuous laser optical path, the continuous laser emitted by the continuous laser 21 passes through the continuous laser collimator 22 and the continuous laser reflector 23a in turn, and reaches the continuous laser galvanometer 23b after reflection. When the laser beam is incident on the high-speed rotating galvanometer, the rotation of the rotating part reflects the laser beam in different directions, realizing rapid scanning and positioning of the laser beam, and finally passes through the continuous laser field mirror 23c to reach the surface of the cleaning workpiece.

[0052] The pulse laser cleaning device includes a pulse laser generator 31 , a pulse laser collimator 32 , a pulse laser galvanometer 33 a , and a pulse laser field mirror 33 b .

[0053] In the pulse laser optical path, the pulse laser emitted by the pulse laser generator 31 passes through the pulse laser collimator 32a, the pulse laser galvanometer 33a in sequence, and then passes through the pulse laser field mirror 33b to reach the surface of the cleaning workpiece.

[0054] The surfaces of the continuous laser reflector 23a, continuous laser galvanometer 23b, and pulse laser galvanometer 33a are all coated with an anti-reflection film with a reflectivity greater than 99%. The surfaces of the continuous laser field mirror 23c and pulse laser field mirror 33b are all coated with an anti-reflection film with a reflectivity less than 1%.

[0055] like Figure 3 As shown, the linear rolling guide 4 positions the pulse laser scanning system 33 through the slider 8 and the fixed hole 9. By moving the slider 8 to different fixed holes 9, the position of the pulse laser scanning system 33 on the linear rolling guide 4 can be adjusted to adjust the distance between the two laser beams, thereby controlling the influence of the residual heat of the continuous laser beam on the pulse laser beam cleaning.

[0056] In practice, the linear rolling guide 4 can be removed for cleaning purposes and replaced with a linear rolling guide with a different number of fixing holes and a different distance between the fixing holes. Linear rolling guides control the sliding distance through rolling elements between the guide rail and the slider, providing high-precision, high-rigidity, and high-speed motion control, thereby achieving control over the distance of the dual laser beams.

[0057] A high-performance CCD camera is fixed on the bracket 1 after the pulse laser beam, and performs real-time photography and monitoring of the workpiece surface after continuous-pulse laser cleaning, analyzes the image results, and adjusts the laser beam spacing according to whether the cleaning requirements are met or damage to the workpiece is caused.

[0058] Example 2

[0059] like Figure 5 shown.

[0060] A cleaning method based on a continuous-pulsed laser non-destructive cleaning device is:

[0061] First, turn on the continuous laser and the pulsed laser at the same time, and adjust the power frequency. In the continuous laser optical path, the continuous laser reflector 23a and the continuous laser galvanometer 23b are both fixed at 45° inside the housing. After the light is reflected by the reflector, the direction of the beam changes by 90° and is 45° to the continuous laser galvanometer lens 7. After entering the continuous laser galvanometer lens 7, the direction of the beam is converted by 90° again and enters the galvanometer. The galvanometer motor 6 drives the galvanometer lens 7 to rotate at high speed to scan the cleaning workpiece; in the pulsed optical path, the pulsed laser galvanometer 33a is fixed at 45°, and the pulsed laser beam is incident on the pulsed laser galvanometer lens at 45°. The beam direction is converted by 90° and enters the pulsed laser field mirror 33b.

[0062] Secondly, if Figure 5 During cleaning, the continuous laser beam 10 scans the workpiece in sequence and simultaneously after the pulsed laser beam 11. A high-performance CCD camera takes real-time photos and monitors after the scanning beam.

[0063] The steps for real-time monitoring using a high-performance CCD camera are as follows:

[0064] 1. Optical imaging: The image of the workpiece being cleaned is imaged onto the CCD photosensitive chip to form a two-dimensional image.

[0065] 2. Signal conversion: The CCD camera converts the image on the photosensitive chip into an electrical signal, which is then amplified and denoised to obtain a high-quality digital image signal.

[0066] 3. Real-time detection algorithm: Use image processing algorithms to analyze whether impurities or dirt on the workpiece surface have been cleared, or detect whether there are cracks or other damage on the workpiece surface.

[0067] 4. Result analysis and feedback control: Through the analysis and feedback control of monitoring results, the cleaning interval can be accurately controlled and adjusted to ensure the cleaning effect and workpiece quality.

[0068] Taking the cleaning of thick layers of rust on steel structures as an example, when a continuous laser beam reaches the workpiece surface, it achieves relatively uniform cleaning. By controlling the parameters, approximately 90% of the surface rust is removed without damaging the substrate. While maintaining residual heat from the continuous laser cleaning process, the workpiece is cleaned by the pulsed laser. Utilizing this residual heat, the pulsed laser effectively removes the remaining rust. During the cleaning process, a high-performance CCD camera captures real-time images of the workpiece surface, analyzing whether the surface meets the cleaning requirements. Based on the results, the spacing between the continuous and pulsed lasers is dynamically adjusted. This effective utilization of residual heat improves the efficiency of the pulsed laser cleaning process and minimizes substrate damage. The sequential application of continuous and pulsed lasers produces superior cleaning results compared to a single pulsed laser of the same power, while also saving energy.

[0069] When used, the present invention simultaneously outputs a continuous laser beam and a pulsed laser beam to sequentially clean the cleaning area. After the continuous laser beam cleans, the pulsed laser beam uses the heat of the continuous laser beam to clean the remaining objects to be cleaned. The cleaning is simultaneously monitored by a high-performance CCD camera, and the distance between the two laser beams is adjusted in real time. The power of the continuous laser beam is greater than that of the pulsed laser beam.

[0070] The above embodiments are only for illustrating the technical solutions of the present invention, and their purpose is to make it easier to understand the contents of the present invention and implement them, but they are not intended to limit the scope of implementation of the present invention.

[0071] Parts not covered by the present invention, such as image processing technology, are the same as the existing technology or can be implemented by using the existing technology.

Claims

1. A non-destructive cleaning device based on continuous-pulse laser, characterized in that: It includes: A bracket, the bracket being used to mount a continuous laser cleaning device, a pulsed laser cleaning device, a linear rolling guide rail, and a high-performance CCD camera; the continuous laser cleaning device is located before the pulsed laser cleaning device, and the high-performance CCD camera is installed after the pulsed laser cleaning device; the slider on the linear rolling guide rail is fixedly connected to the pulsed laser scanning system; A continuous laser cleaning device, comprising a continuous laser generator, a continuous laser collimator and a continuous laser scanning system; A pulsed laser cleaning device comprising a pulsed laser generator, a pulsed laser collimator and a pulsed laser scanning system; A linear rolling guide rail is provided with a slider, the slider is provided with a fixing hole, and the pulse laser scanning system is installed on the slider through the fixing hole and is connected to the retractable lens barrel; A high-performance CCD camera is installed after the pulse laser cleaning device and is used to capture images of the surface of the workpiece after cleaning.

2. The non-destructive cleaning device based on continuous-pulse laser according to claim 1, characterized in that: The optical path of the continuous laser cleaning device is equipped with a continuous laser collimator, a continuous laser reflector, a continuous laser high-speed rotating galvanometer and a continuous laser field mirror in sequence, and the continuous laser passes through the continuous laser collimator, the continuous laser reflector, the continuous laser high-speed rotating galvanometer and the edge continuous laser field mirror in sequence.

3. The non-destructive cleaning device based on continuous-pulse laser according to claim 1, characterized in that: The pulse laser optical path of the pulse laser cleaning device is provided with a pulse laser collimator, a pulse laser high-speed rotating galvanometer and a pulse laser field mirror in sequence, and the pulse laser passes through the pulse laser collimator, the pulse laser high-speed rotating galvanometer and the pulse laser field mirror in sequence.

4. The non-destructive cleaning device based on continuous-pulse laser according to claim 1, characterized in that: The optical path of the pulse laser scanning system is placed in the telescopic lens barrel. When the pulse laser scanning system moves, the telescopic lens barrel is also telescoped.

5. The non-destructive cleaning device based on continuous-pulse laser according to claim 1, characterized in that: The high-performance CCD camera is fixed in position and shoots the workpiece surface vertically downward.

6. The non-destructive cleaning device based on continuous-pulse laser according to claim 1, characterized in that: The bottom of the pulse laser scanning system is provided with a plurality of mounting holes for connecting with the slider.

7. The non-destructive cleaning device based on continuous-pulse laser according to claim 2, characterized in that: The continuous laser field mirror in the continuous laser scanning system is a lens group, and the surface is coated with an anti-reflection film.

8. A cleaning method based on the cleaning device according to claim 1, Its characteristics are as follows: first, turning on the continuous laser and the pulsed laser at the same time, and adjusting the power frequency; in the continuous laser optical path, the continuous laser reflector and the continuous laser galvanometer are both fixed at 45 degrees inside the shell; after the light is reflected by the reflector, the beam direction changes by 90 degrees and forms a 45 degree angle with the continuous laser galvanometer lens. After entering the continuous laser galvanometer lens, the beam direction is changed by 90 degrees again and enters the galvanometer lens; the galvanometer motor drives the galvanometer lens to rotate at high speed to scan the cleaning workpiece; in the pulsed optical path, the pulsed laser galvanometer is fixed at 45 degrees, the pulsed laser beam is incident on the pulsed laser galvanometer lens at 45 degrees, the beam direction is changed by 90 degrees, and is incident on the pulsed laser field mirror; Secondly, during cleaning, the continuous laser beam scans the workpiece in sequence and simultaneously after the pulsed laser beam; the high-performance CCD camera takes real-time photos and monitors after the scanning beam; When the continuous laser beam reaches the workpiece surface, it achieves relatively uniform cleaning. By controlling the parameters, it can achieve a cleaning level of about 90% of the surface rust without causing damage to the substrate. The workpiece is cleaned by the pulsed laser while maintaining the residual heat from the continuous laser cleaning. By utilizing the residual heat, the pulsed laser can efficiently remove the remaining rust. During the cleaning process, a high-performance CCD camera captures the workpiece surface image in real time, analyzes whether the workpiece surface meets the cleaning requirements, and dynamically adjusts the spacing between the continuous laser and the pulsed laser based on the results. This effectively utilizes residual heat to improve the pulsed laser cleaning efficiency and reduce the degree of substrate damage. The sequential action of continuous laser and pulse laser can produce better cleaning effect than single pulse laser of the same power and save energy.

9. The method according to claim 8, wherein: The steps for real-time monitoring using a high-performance CCD camera are as follows: 1) Optical imaging: The image of the workpiece being cleaned is imaged onto a CCD photosensitive chip to form a two-dimensional image; 2) Signal conversion: The CCD camera converts the image on the photosensitive chip into an electrical signal, which is then amplified and de-noised to obtain a high-quality digital image signal. 3) Real-time detection algorithm: Use image processing algorithms to analyze whether impurities or dirt on the workpiece surface have been removed, or detect whether cracks or other damage have appeared on the workpiece surface; 4) Result analysis and feedback control: Through analysis and feedback control of monitoring results, precise control and adjustment of cleaning intervals can be achieved to ensure cleaning effect and workpiece quality.

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