Laser-induced self-healing repair device and method for thermoplastic composite material

Abstract

The invention relates to a laser-induced self-healing repair device and method for a thermoplastic composite material, and belongs to the field of defect repair of composite materials. The device comprises a laser generator, an infrared imager, a laser range finder, a laser ultrasonic sensor, an air compressor and a material storage bin which are all centrally controlled by a control system. The infrared imager detects and positions a damaged area of the repairing material, and the laser range finder measures the distance between the welding gun and a target area so as to regulate and control the position of the welding gun. The material storage bin can provide a filling material with a self-healing function as required, mainly polyamidoimine, and the filling material is broken and recombined at high temperature to realize the self-healing function; the air compressor is used for cooling the repair area to prevent overheating. According to the method, laser energy is used for inducing the material to be heated and fused, precise self-healing repairing is achieved, and the repairing quality and consistency are improved through whole-process automatic control. The method is suitable for damage repair of the thermoplastic composite material, and has the advantages of high repair efficiency, accurate positioning, high material utilization rate, environmental friendliness and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material repair, and in particular relates to a device and method for automatic positioning and repair of thermoplastic composite materials induced by laser, which realizes automatic positioning with the assistance of an infrared imager and a laser ultrasonic sensor. Background Art

[0002] With the increasing use of thermoplastic composites in industry and aerospace, the durability and self-healing ability of materials have gradually become key research directions. Thermoplastic composites are widely used in the manufacture of various structural components due to their light weight, high strength and good corrosion resistance. However, these materials are susceptible to external impact, scratches and fatigue during use, resulting in microcracks or local damage. If these damages are not repaired in time, they will seriously affect the performance and service life of the material, and then threaten the safety and reliability of the entire structure. Traditional repair methods such as mechanical repair or adhesive repair are often unable to effectively deal with tiny cracks and complex damage. In addition, traditional repair methods are usually time-consuming and inefficient, and it is difficult to ensure that the performance of the repaired material is equivalent to that of the raw material.

[0003] To solve the above problems, the present invention proposes a laser-induced self-healing repair device and method for thermoplastic composite materials. The device integrates key components such as infrared imager positioning device, laser rangefinder and laser ultrasonic sensor, which can realize efficient identification, precise repair and real-time monitoring of the damaged area of ​​thermoplastic composite materials. Through the high-energy excitation of the laser welding gun and the real-time monitoring technology, the temperature of the material is uniform and the repair effect is good during the self-healing process, thereby significantly improving the service life and safety of thermoplastic composite materials. Summary of the invention

[0004] In view of the current problems of low repair quality and slow positioning speed of thermoplastic composite materials, the present invention provides a laser-induced self-healing repair device and method for thermoplastic composite materials.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A laser-induced self-healing repair device and method for thermoplastic composite materials, characterized in that the device mainly comprises an infrared thermal imaging system (1), an air gun (2), an ultrasonic sensor self-healing monitoring system (3), a laser ranging system (5), a robot motion system (8), a data processing system (9), a control system (10), a material supply system (11), an air compressor (12), a CO2 laser generator (13), a fiber laser generator (14), and a protective gas (15), wherein:

[0007] The infrared thermal imaging system is composed of two infrared thermal imagers (1) connected to a welding gun (7) through a screw rod; the imager and the welding gun move synchronously to ensure that the area scanned by the imager is in the same position as the welding gun, thereby improving positioning accuracy. After the infrared imager scans the target area, a temperature schematic diagram within the area is obtained, and the temperature abnormal area is the area to be repaired. The data is then transmitted to a data processing system (9). At the same time, a laser ultrasonic sensor emits ultrasonic waves to detect flaws on the material surface, assisting the infrared imager to further complete positioning analysis, and then transmitting the information to a control system (10). The control system controls a six-axis robot to move the welding gun to the temperature abnormal area.

[0008] The laser distance measuring system is composed of a laser distance meter (5) and a fixing device (4). The distance meter emits laser pulses, which are reflected back after encountering a target object and captured by a receiver of the distance meter. The distance meter measures the time from the emission to the return of the laser pulse, thereby determining the distance between the welding gun muzzle and the repair object. The distance between the welding gun and the object is controlled according to the type of repair material and the type of defect, thereby ensuring that an ideal repair distance is achieved.

[0009] The cooling system comprises an air gun (2), a fixing device (4) and an air compressor (12). The welding gun is embedded in the fixing device. The air gun port can be adjusted to focus on the same area as the welding gun port. After the laser repair is completed, the repair area needs to be cooled down due to the characteristics of the material to avoid excessive temperature in the repair area, which may lead to degradation or deformation failure. The wind speed and temperature of the air outlet can be adjusted under the control of the control system. If the material cools too fast or too slow, the quality of the repair will be affected.

[0010] The self-healing monitoring system is composed of a laser ultrasonic sensor (3). The ultrasonic wave excited by the sensor propagates in the material and scatters, reflects or attenuates when encountering cracks or defects. By measuring the changes in the ultrasonic signal, the location, size and depth of the crack in the material can be detected as the basis for monitoring the self-healing process. During the self-healing process, as the crack gradually closes, the reflection and scattering of the ultrasonic wave will decrease, and the intensity of the ultrasonic wave passing through the damaged area will increase. By comparing the ultrasonic signals at different time points, the progress of self-healing can be tracked in real time. After self-healing is completed, the laser ultrasonic sensor can detect the internal structure of the material again to determine the repair effect. Compared with the initial state, if the ultrasonic signal changes back, it indicates that the self-healing process is relatively successful and the material structure has been restored.

[0011] The laser generator system comprises a CO2 laser (13) and a fiber laser (14). The two laser generators can be switched for use in different occasions. When repairing large-area defects or large parts, the CO2 laser generator is used. Its laser wavelength is longer than that of the fiber laser generator, and its heat-affected zone is larger, which is suitable for repairing large parts. When repairing local defects and delicate parts, the fiber laser generator is used. The fiber laser generator has high efficiency, good stability, and better beam quality than the CO2 laser generator.

[0012] The device and method for laser-induced self-healing repair of thermoplastic composite materials are characterized in that the device integrates an automatic positioning system of an infrared imager (1) and a laser rangefinder (5), and the positioning accuracy of the device is high. The infrared imager uses the different temperatures of different objects to capture temperature difference signals to achieve the positioning function. The laser rangefinder assists the positioning of the infrared imager, which can accurately calculate the relative distance between the welding gun (7) and the repair object, so that the six-axis robot (8) can accurately move the welding gun to the ideal repair position.

[0013] The laser-induced self-healing repair device and method for thermoplastic composite materials are characterized in that the device of the present invention is different from a traditional single laser source repair device. The device is equipped with two laser sources, namely a CO2 laser generator (13) and a fiber laser generator (14), which are suitable for repairing different types of workpieces. The laser system is controlled by a control system, and the control determines the use of the laser source based on the image feedback of the infrared imager, thereby realizing a highly automated repair process.

[0014] The laser-induced self-healing repair device and method for thermoplastic composite materials are characterized by comprising the following steps:

[0015] Step 1: Start the control system and check the working status of the infrared imager (1), the laser ultrasonic sensor (3), the laser rangefinder (5), the welding gun (7), the air compressor (12) and the material storage bin (11), ensuring that all devices are connected normally and that the laser light source of the laser welding gun is in standby mode.

[0016] Step 2: Use an infrared imager to scan the thermoplastic composite material to be repaired to obtain a thermal imaging image of the target position, and then use a laser ultrasonic sensor to detect the material and obtain an acoustic wave signal. The control system (10) analyzes the imaging data to determine the exact position and shape of the damaged area. The six-axis robot (8) is started, and the control system controls the robot to move the welding gun to the repair position.

[0017] Step three, the laser rangefinder (5) emits a laser beam to measure the physical distance between the welding gun (7) and the target repair area, and the measurement result is fed back to the control system. The control system accurately adjusts the position of the welding gun based on the distance measurement result to align it with the damaged area, ensuring that the welding gun remains at the optimal repair distance to optimize the transmission effect of the laser energy.

[0018] Step 4: The self-healing polyamide-imide and other materials are transported from the material storage bin (11) to the repair area through the control system (10), ensuring that the type and quantity of the repair materials meet the repair requirements. Activate the laser welding gun, select a suitable laser generator to start laser emission, and repair the thermoplastic composite material. The control system monitors the temperature changes during the welding process in real time to ensure the melting of the material.

[0019] Step 5: After the laser welding is completed, the air compressor (12) is started for cooling to quickly reduce the temperature of the repaired area to prevent the material from overheating and causing deformation and thermal degradation. After cooling is completed, the laser ultrasonic sensor is used again to detect the material and evaluate the repair effect.

[0020] The beneficial effects of the present invention are:

[0021] The automatic positioning system of the present invention combines an infrared imager, a laser rangefinder and a laser ultrasonic sensor to ensure accurate control of the welding gun position, thereby improving the accuracy and consistency of the repair and reducing errors in the repair process. The fully automatic control system makes the operation easy, reduces manual intervention, and improves operational safety and reliability. The design of the material storage bin can supply materials with self-healing functions according to actual needs, avoid waste, and improve material utilization; the cooling design of the air compressor can quickly reduce the temperature of the repair area, prevent the material from overheating and deformation, and ensure the quality of the repair, and the device can adapt to thermoplastic composite materials of different types and shapes; the design of the self-healing monitoring system can detect the repair effect in real time, and can also realize the monitoring function in the repair of complex surfaces. The invention has important application value and market potential in the field of thermoplastic composite repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a laser-induced self-healing repair device and method for thermoplastic composite materials provided by the present invention;

[0023] Figure 2 It is a schematic diagram of an infrared imaging positioning system, a laser ranging system and an ultrasonic sensing self-healing monitoring system for a thermoplastic composite laser-induced self-healing repair device and method provided by the present invention;

[0024] Figure 3It is a schematic diagram of a fixing device for a laser-induced self-healing repair device and method for thermoplastic composite materials provided by the present invention;

[0025] Explanation of numbers in the figure: 1. Infrared imager; 2. Air gun; 3. Laser ultrasonic sensor 4. Fixing device; 5. Laser rangefinder; 6. Material pipe; 7. Welding gun; 8. Six-axis robot; 9. Data processing system; 10. Control system; 11. Material storage bin; 12. Air compressor; 13. CO2 laser generator; 14. Fiber laser generator; 15. Protective gas. DETAILED DESCRIPTION

[0026] The present invention relates to a laser-induced self-healing repair device and method for thermoplastic composite materials, and the present invention is further described in detail below through drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Figure 1 It is a specific embodiment of the present invention. The figure shows a laser-induced self-healing device for thermoplastic composite materials. The device of the present invention is proposed to address a series of problems such as slow positioning speed and low precision of traditional thermoplastic composite material repair methods. The core part of the device is a positioning system that integrates an infrared imager and a laser rangefinder. The laser ultrasonic sensor is used as an auxiliary positioning, and the infrared imaging uses the different temperatures of different objects to achieve precise positioning. It is also equipped with an automatic material conveying system, a cooling system and a self-healing monitoring system. During repair, polyamideimide with self-healing function is transported to the target area. The material will break and recombine at high temperatures. The cooling system can timely reduce the temperature of the repair area to ensure the quality of the repair.

[0028] In the embodiment, the repaired material is mainly polyetheretherketone-based composite materials used in the aerospace and automotive fields. The main components of the device are opened by the control system to ensure that each component can be used normally, and the infrared imager is started to scan the repaired workpiece to obtain preliminary positioning information. The motion system moves the welding gun to the specified position, and then uses the laser rangefinder and laser ultrasonic sensor to assist in positioning. After the positioning is completed, the laser welding gun is activated to preheat and the laser generator is started; this example repairs fine workpieces in a local range, and a fiber laser generator is selected. The process parameters are laser power P = 500W, scanning speed v = 0.8m / min, defocus z = 5mm, and spot diameter is 0.8mm (the spot diameter of large repair is selected between 1 and 2mm); the repair filling material is polyamide imide (melting point is 280-340℃, service temperature is -196-260℃), which can still maintain good mechanical strength, rigidity and corrosion resistance at 260℃. During the repair of the workpiece, the whole process is monitored, and if the repair path deviates, it is adjusted in time. The cooling system is immediately activated to cool down the repaired area, realizing a dynamic process of repairing and cooling at the same time.

[0029] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A laser-induced self-healing repair device and method for thermoplastic composite materials, characterized in that: It mainly includes infrared thermal imaging system (1), air gun (2), ultrasonic sensor self-healing monitoring system (3), laser ranging system (5), robot motion system (8), data processing system (9), control system (10), material supply system (11), air compressor (12), CO2 laser generator (13), fiber laser generator (14), and protective gas (15); The infrared thermal imaging system is composed of two identical infrared imagers (1) connected to the welding gun via a screw rod. The infrared imager (1) is located at the front end of the welding gun to facilitate scanning and repairing the target area. The scanned data is fed back to the data processing system (9) and further processed by the control system to control the movement of the robot. The laser distance measurement system comprises a laser distance meter (5) and a fixing device (4). The laser distance meter is connected to the fixing device via a screw rod. The laser distance meter measures the relative position between the repair target area and the welding gun, so as to facilitate the six-axis robot (8) to accurately control the welding gun. The distance meter feeds back distance information in real time to achieve accurate positioning. The cooling system comprises an air gun (2), a fixing device (4) and an air compressor (12); the air gun (2) is fixed to the fixing device (4) by embedding; the air gun (2) and the air compressor (12) are connected via an air duct; the cooling system can rapidly cool down and solidify the cladding area; at high temperatures, thermoplastic composite materials are prone to problems such as thermal aging, degradation, thermal deformation and warping, which weaken the performance of the material and shorten its service life. The self-healing monitoring system is composed of a laser ultrasonic sensor (3), which is a non-contact sensor. When damage or cracks occur in the thermoplastic composite material, the ultrasonic sensor can detect the existence, position and size of the cracks through the time delay and intensity change of the ultrasonic echo, thereby assisting the automatic positioning of the infrared imager. At the same time, during the self-healing material repair process, the cracks on the surface and inside of the material gradually close and repair, and the propagation characteristics of the ultrasonic signal (such as reflection, attenuation and scattering) will change. By monitoring the changes in the ultrasonic signal, the progress of the self-healing process can be evaluated in real time. The laser generator system includes a CO2 laser (13) and a fiber laser (14). The advantage of the CO2 laser in the repair of thermoplastic composite materials is that its wavelength is suitable for efficient absorption of polymer materials, can achieve deep penetration and rapid heating, and is suitable for large-area repair work. The fiber laser is known for its high power density and good beam quality, can achieve fine cutting and welding, is suitable for the repair of complex structures, and has greater flexibility and can be operated in a small space. Therefore, the selection of the laser is determined according to the type of the workpiece to be repaired.

2. The laser-induced self-healing repair device and method for thermoplastic composite materials according to claim 1, characterized in that: The infrared imaging system receives infrared radiation from objects and converts it into a visible image based on the different intensities of infrared radiation emitted by objects at different temperatures. The temperature of the repaired area is usually higher than the surrounding unaffected areas, resulting in a significant thermal mismatch (i.e., temperature difference) between the repaired area and the unheated area. The infrared imager can clearly capture this temperature difference and thus accurately locate the repaired area.

3. The laser-induced self-healing repair device and method for thermoplastic composite materials according to claim 1, characterized in that: The laser rangefinder calculates the distance between the welding gun and the target area by emitting a laser beam and measuring the time difference of the laser beam reflecting from the target surface. The laser rangefinder is installed on the welding gun and can continuously emit laser and receive reflected signals during the welding process to achieve real-time distance monitoring. As the welding gun moves over the repair area, the rangefinder can continuously measure the distance between the welding gun and the workpiece surface and feed the information back to the control system. If it deviates from the ideal distance, the control system will immediately make adjustments to ensure the quality of the repair.

4. The laser-induced self-healing repair device and method for thermoplastic composite materials according to claim 1, characterized in that: The laser generator in this device is not single, and the repair quality is largely related to the type of laser generator. This device is equipped with CO2 laser and fiber laser, and the two lasers are suitable for different repair scenarios. CO2 laser emits red light with a wavelength of 10.6um, so the heat generated by CO2 laser has a large diffusion range and is suitable for large-area repair; fiber laser has a common emission wavelength of 1.07um, with high efficiency and flexible energy control, suitable for fine repair of local damage of complex shapes.

5. The use of the laser-induced self-healing repair device and method for thermoplastic composite materials according to claim 1 specifically comprises the following steps: Step 1: Use an infrared thermal imager (1) to scan the thermoplastic composite material and identify the temperature abnormality area; the damaged or defective area of ​​the thermoplastic composite material will show a temperature difference when heated. The control system receives and analyzes the data of the infrared imager, identifies the temperature abnormality area as the repair area, and generates a repair path. At the same time, the ultrasonic sensor emits ultrasonic waves to assist in positioning and identify the location and size of the defect. Step 2: The control system (9) controls the six-axis robot (8) to move the welding gun (7) to the initially designated area of ​​the scanning result, and starts the laser rangefinder (5) to measure the distance from the welding gun to the surface of the repair area to ensure that the welding gun is at an ideal working distance. According to the distance measurement data, the six-axis robot moves the welding gun to a precise position and adjusts the distance between the welding gun and the material surface to ensure uniform coverage of the repair area. Step 3: The welding gun (7) is heated to a predetermined temperature, and the laser beam is concentratedly heated on the defective area. At the same time, a material with self-healing function such as polyamide imide is transported from the material storage bin to the repair area so that it melts and fills the defect; the control system (9) moves the welding gun according to the generated repair path to ensure that the welding gun moves smoothly along the set trajectory to evenly cover the defective area. Step 4: After the repair is completed, the air compressor (12) is immediately started to spray cooling air to the repair area to control the cooling speed of the material and the temperature of the repair area to avoid deformation of the material, fiber damage or thermal degradation of the material. Step 5: After the repaired area has cooled down, start the ultrasonic sensor again to confirm whether the defective area has been completely repaired, and check the uniformity of the repaired layer and whether there are any defects such as cracks. If incomplete repair or new defects are detected, the control system will automatically repeat the repair process until the qualified standards are met.

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