Laser removal method and equipment for ceramic coating on aircraft engine turbine blades

Abstract

The present invention discloses a method and apparatus for laser removal of ceramic coatings from aircraft engine turbine blades, relating to the field of surface cleaning technology. The apparatus comprises a control cabinet, a drive platform, a work head, an image acquisition module, a clamping module, an operating panel, and the like. Regional division and thickness identification of the ceramic coating on the blade surface are achieved solely through an image acquisition module based on infrared thermal imaging technology, reducing the complexity of the processing system and equipment costs. The drive platform utilizes a gantry-style five-degree-of-freedom drive mechanism, with the five degrees of freedom encompassing movement along the x-, y-, and z-axes, and rotation about the a- and b-axes, adapting to the processing of complex blade surface shapes. A clamping module with adaptive centering and reliable clamping eliminates processing chatter or deformation, and their adverse effects on trajectory planning and processing accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of surface cleaning, and in particular to a method and equipment for laser removal of ceramic coatings on turbine blades of aircraft engines. Background Art

[0002] Because aircraft engine turbine blades are required to operate for extended periods in high-temperature, high-pressure environments, they are typically coated with ceramic thermal barrier coatings to effectively enhance their heat resistance and service life. Ceramic thermal barrier coatings, typically composed of ceramic materials such as yttria-stabilized zirconia (YSZ), offer excellent thermal insulation properties, capable of reducing substrate temperatures by hundreds of degrees Celsius. However, over time, ceramic coatings gradually age, crack, and flake, losing their protective properties. Therefore, efficient and non-destructive removal of these failed coatings is essential during turbine blade remanufacturing and maintenance.

[0003] Traditional coating removal methods, including mechanical or chemical methods like sandblasting and chemical etching, suffer from low precision, severe environmental pollution, and extensive damage to the substrate. In recent years, laser removal technology has become a research hotspot for ceramic coating removal due to its high energy density, non-contact processing, and strong controllability. Lasers heat the coating in a short period of time, causing it to expand, melt, or vaporize, thereby stripping it. This method offers advantages such as high removal efficiency, a small heat-affected zone, and strong automation potential.

[0004] However, existing laser removal technologies face challenges in identifying coating areas, thickness, and reliable blade clamping. Coating area identification typically relies on machine vision systems, high-precision 3D laser scanning, or infrared thermal imaging. After identifying the coating areas, ultrasonic testing, laser-induced ultrasound, eddy current testing, or optical interferometry are used to identify the thickness of different coating areas. It's impossible to simultaneously identify both coating area and thickness using the same system. Furthermore, due to the blade's complex structure, traditional blade clamping can easily lead to machining vibration or deformation, directly impacting trajectory planning and machining accuracy. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser removal processing method that can simultaneously identify the ceramic coating area and thickness only through infrared thermal imaging technology, and based on this method, provide a five-axis linkage laser processing equipment that can adaptively center the blade and provide reliable clamping.

[0006] In response to the above technical problems, the technical solution adopted by the present invention is: a laser removal method for ceramic coating of aircraft engine turbine blades, characterized by comprising the following steps:

[0007] Step S1: A single blade is clamped and fixed, and hot air is continuously blown onto the blade surface from all sides of the blade. After the hot air stops blowing, the blade is allowed to cool naturally. The duration of natural cooling is the cooling time. When the cooling time expires, the surface temperature distribution of two sides of the blade body is photographed in sequence by a thermal imager. The two sides of the blade body are the blade basin curved surface and the blade back curved surface;

[0008] Step S2: Save both surface temperature distribution maps as grayscale images. The pixel values in the grayscale images represent the temperature values at the pixel points. Perform edge detection on the grayscale images to obtain boundary lines of temperature mutations. A closed area enclosed by a boundary line that does not contain other boundary lines, or a closed area enclosed between two inner and outer nested boundary lines, is an isothermal area.

[0009] Step S3: setting a threshold temperature, the isothermal area with an average temperature greater than or equal to the threshold temperature is the coating residual area, and the isothermal area with an average temperature less than the threshold temperature is the metal exposed area;

[0010] Step S4: estimating the surface area of each coating residual area based on the imaging parameters of the thermal imager and the total number of pixels in each coating residual area; estimating the coating thickness of each coating residual area based on the surface area and average temperature of each coating residual area, the physical properties of the coating material, the ambient temperature, the energy parameters of the hot air, and the time parameter when the thermal imager photographs the surface of the coating residual area;

[0011] Step S5: The laser cleaning head is mounted on a gantry-type five-degree-of-freedom drive mechanism, and based on the coating thickness and the material removal characteristic parameters of the laser cleaning head, trajectory planning for the laser cleaning operation of the coating residual area on the entire blade side is completed through offline programming;

[0012] Step S6: Laser clean the surface of the current blade according to the result of trajectory planning. After cleaning, perform quality inspection on the current blade. Remove the unclean blade from the surface coating as the blade to be cleaned, and complete the operations of steps S1 to S5 again.

[0013] Furthermore, in step S1, the temperature of the hot air ranges from 200°C to 255°C; the time for continuously blowing the hot air is the heating time, and the heating time ranges from 30s to 120s; the cooling time ranges from 10s to 60s.

[0014] Furthermore, in step S2, the edge detection process includes the following steps:

[0015] Step S21: De-noising the grayscale image through Gaussian filtering;

[0016] Step S22: using a histogram equalization algorithm to perform contrast enhancement on the denoised grayscale image;

[0017] Step S23: Apply the Sobel algorithm or the Canny algorithm to perform edge detection on the grayscale image that has undergone contrast enhancement processing, and the identified edge line is the boundary line.

[0018] Furthermore, in step S3, the threshold temperature ranges from 100°C to 150°C.

[0019] Furthermore, in step S4, the surface area of the coating residual area is calculated as follows:

[0020] ;

[0021] Where, A is the surface area of the current coating residual area; is the surface curvature coefficient of the current coating residual area, ranging from 1 to 1.5; is the total number of pixels in the current coating residual area; W is the width of the thermal imager sensor; H is the height of the thermal imager imaging sensor; M The lateral resolution of the thermal imager's pictures; K The vertical resolution of the thermal imager's pictures; r is the average of the shortest and longest distances between the thermal imager lens and the blade side; f is the focal length of the thermal imager.

[0022] Furthermore, in step S4, the calculation formula for the coating thickness of the coating residual area is:

[0023] ;

[0024] Where, d is the coating thickness of the current coating residual area; is the compensation coefficient of the current coating residual area; k is the thermal conductivity of the coating in the current coating residual area; t The cumulative time from the start of natural cooling of the blade to the current coating residue area being photographed by the thermal imager; The material density of the coating in the current coating residual area; c is the specific heat capacity of the coating in the current coating residual area; is the heating efficiency of hot air, ranging from 0.3 to 0.7; P The output power of the equipment providing hot air; The current coating residual area is t Average temperature at the time; The surrounding environment of the current coating residue area is t The temperature of the moment; It is the compensation adjustment amount of the current coating residual area.

[0025] The present invention also proposes a laser processing equipment based on the laser removal method of ceramic coating on aircraft engine turbine blades, including a control cabinet, a drive platform, a sealing cover, a working head, an image acquisition module, a shift linear module, a clamping module, an operating panel, a ventilation filter, and a cabin door, characterized in that: the drive platform and the shift linear module are both fixedly installed on the control cabinet; a working head is installed at the end of the drive platform, and the working head is a laser cleaning head; the sealing cover is fixedly installed on the control cabinet; the drive platform and the shift linear module are both located in the sealing cover; the image acquisition module is hoisted in the sealing cover; the clamping module is fixedly installed on the moving end of the shift linear module; the clamping module is used to clamp the blade to be processed; the operating panel is rotatably installed on the side of the control cabinet; the ventilation filter is fixedly installed on the top of the sealing cover; and the cabin door is hinged on the side of the sealing cover.

[0026] Furthermore, the driving platform includes a pillar, an x-axis linear module, a y-axis linear module, a z-axis linear module, an a-axis rotary module, and a b-axis rotary module; there are two x-axis linear modules; each x-axis linear module is fixedly connected to the control cabinet through two pillars; both ends of the y-axis linear module are fixedly connected to the moving end of an x-axis linear module; the z-axis linear module is fixedly installed on the moving end of the y-axis linear module; the a-axis rotary module is fixedly installed on the moving end of the z-axis linear module; the b-axis rotary module is fixedly installed on the rotating end of the a-axis rotary module; and the working head is fixedly connected to the rotating end of the b-axis rotary module.

[0027] Furthermore, the image acquisition module includes a hanging plate, a first motor, a cantilever, a sliding shaft, and an infrared camera; the hanging plate is fixedly installed in the sealing cover; the first motor is fixedly installed on the hanging plate; the first end of the cantilever is fixedly installed on the output shaft of the first motor; the second end of the cantilever is an elastic clip structure with screws, and the sliding shaft is slidably installed in the elastic clip and tightened by screws; the infrared camera is fixedly installed at the end of the sliding shaft; the infrared camera uses a thermal imager.

[0028] Furthermore, the clamping module includes a bracket, a second motor, a sliding sleeve, a spindle, a secondary cone block, a main cone block, a secondary connecting rod, a main connecting rod, a boss, a slide rod, a hollow stud, a spring, a clamping ball, a nozzle, a hot air blower, and an air outlet; the bracket is fixedly connected to the moving end of the displacement linear module; the second motor is fixedly mounted on the bracket; the sliding sleeve is fixedly mounted on the output shaft of the second motor; the middle part of the spindle and the bracket are rotatably connected by threaded fitting; both ends of the spindle are square shaft structures; the main cone block is fixedly mounted on the square shaft at the first end of the spindle; the boss is hinged on the square shaft at the first end of the spindle; the secondary cone block is fixedly mounted on the square shaft at the first end of the spindle The cone block is fixedly mounted on the square shaft at the second end of the spindle; the square shaft at the second end of the spindle is inserted into the sliding sleeve and is slidably connected to the sliding sleeve; the cone apex angle of the secondary cone block is greater than the cone apex angle of the main cone block; the middle circumferences of the two main connecting rods are evenly hinged on the bracket; the middle circumferences of the two secondary connecting rods are evenly hinged on the bracket; the root base of the blade to be processed includes four positioning side surfaces and a positioning bottom surface; the first positioning side surface and the third positioning side surface of the root base of the blade to be processed are tenon tooth structures, and the surface of the tenon tooth structure is a wavy curved surface; the second positioning side surface and the fourth positioning side surface of the root base of the blade to be processed are The side surface is a positioning end surface, and the positioning end surface is a plane; the positioning bottom surface of the base of the root of the blade to be processed is a plane; the first end of the main connecting rod is provided with a cylindrical surface structure for clamping the tenon structure; the second end of the main connecting rod is provided with a spherical structure that is in contact with the sliding point of the main cone block; the first end of the secondary connecting rod is rotatably installed with a hollow stud through thread cooperation; a sliding rod is slidably installed in the hollow stud; a clamping ball is fixedly installed at the end of the sliding rod; a spring is provided on the sliding rod, and the two ends of the spring are respectively fixedly connected to the clamping ball and the hollow stud; the clamping ball is used to clamp the base of the root of the blade to be processed The second end of the auxiliary connecting rod is provided with a spherical structure which is in contact with the sliding point of the auxiliary cone block; the boss is used to fit the positioning bottom surface of the base of the root of the blade to be processed; the rotation axis of the main connecting rod on the bracket is orthogonal to the rotation axis of the auxiliary connecting rod on the bracket; four nozzles are fixedly installed on the bracket evenly distributed around the circumference, and a nozzle is provided between every two adjacent main connecting rods and auxiliary connecting rods; the first end of the nozzle faces the blade to be processed; the hot air blower is fixedly installed on the bracket; four air outlets are provided on the hot air blower; each air outlet is connected to the second end of a nozzle through a pipeline.

[0029] Compared with the prior art, the present invention has the following advantages: (1) the area division and thickness identification of the ceramic coating on the blade surface are achieved only through an image acquisition module based on infrared thermal imaging technology, which reduces the complexity of the processing system and reduces the equipment cost; (2) since each pixel in infrared thermal imaging corresponds to a temperature point, a thickness distribution map with micron-level resolution can be generated to accurately locate the residual coating area and thickness; (3) the driving platform adopts a gantry-type five-degree-of-freedom driving mechanism, and the five degrees of freedom are movement along the x-axis, y-axis and z-axis, and rotation around the a-axis and b-axis, which can adapt to the processing of complex blade surface shapes; (4) the clamping module with adaptive centering and reliable clamping is adopted to eliminate processing vibration or deformation and its adverse effects on trajectory planning and processing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flow chart of the laser removal method for ceramic coatings on aircraft engine turbine blades.

[0031] Figure 2 This is the general assembly diagram of the laser processing equipment of the present invention.

[0032] Figure 3 This is a schematic diagram of the structure and installation relationship of various transmission components on the control cabinet of the present invention.

[0033] Figure 4 It is a schematic structural diagram of the clamping module of the present invention.

[0034] In the figure: 1-control cabinet; 2-drive platform; 3-sealing cover; 4-working head; 5-image acquisition module; 6-shift linear module; 7-clamping module; 8-operation panel; 9-ventilation filter; 10-cabinet door; 11-blade to be processed; 201-pillar; 202-x-axis linear module; 203-y-axis linear module; 204-z-axis linear module; 205-a-axis rotation module; 206-b-axis rotation module; 501-hanging plate; 5 02-first motor; 503-cantilever; 504-sliding shaft; 505-infrared camera; 701-bracket; 702-second motor; 703-sliding sleeve; 704-spindle; 705-secondary cone block; 706-main cone block; 707-secondary connecting rod; 708-main connecting rod; 709-boss; 710-sliding rod; 711-hollow stud; 712-spring; 713-clamping ball; 714-nozzle; 715-hot air blower; 716-air outlet. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods. The accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual drawings, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, certain components of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of actual products. It is understandable to those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0036] Figures 1 to 4 It is a preferred embodiment of the present invention.

[0037] like Figure 1 As shown, the laser removal method of ceramic coating on aero-engine turbine blades of the present invention comprises the following steps:

[0038] Step S1: clamp and fix a single blade, and continuously blow hot air onto the blade surface from all sides of the blade, the temperature of the hot air ranges from 200°C to 255°C, and is 230°C in this embodiment; the time for continuously blowing hot air is the heating time, and the heating time ranges from 30s to 120s, and is 80s in this embodiment; after the hot air stops blowing, the blade is allowed to cool naturally, and the duration of natural cooling is the cooling time, and the cooling time ranges from 10s to 60s, and is 30s in this embodiment; when the cooling time expires, the surface temperature distribution diagrams of the two sides of the blade body are sequentially photographed by a thermal imager, and the two sides of the blade body are the blade basin curved surface and the blade back curved surface;

[0039] Step S2: Save both surface temperature distribution maps as grayscale images, where the pixel values in the grayscale images represent the temperature values at the pixel points; perform denoising on the grayscale images using Gaussian filtering; perform contrast enhancement on the denoised grayscale images using a histogram equalization algorithm; perform edge detection on the contrast-enhanced grayscale images using a Sobel algorithm or a Canny algorithm, identify the edge lines as boundary lines, and obtain boundary lines of temperature mutations; a closed area enclosed by a boundary line that does not contain other boundary lines, or a closed area enclosed between two inner and outer nested boundary lines, is an isothermal area;

[0040] Step S3: Setting a threshold temperature. The threshold temperature range is 100°C to 150°C, and in this embodiment, 140°C is used. The isothermal region with an average temperature greater than or equal to the threshold temperature is the coating residue region, and the isothermal region with an average temperature less than the threshold temperature is the metal exposure region.

[0041] Step S4: Estimate the surface area of each coating residue area based on the imaging parameters of the thermal imager and the total number of pixels in each coating residue area. The surface area of the coating residue area is calculated as follows:

[0042] ;

[0043] Where, A is the surface area of the current coating residual area; is the surface curvature coefficient of the current coating residual area, ranging from 1 to 1.5; is the total number of pixels in the current coating residual area; W is the width of the thermal imager sensor; H is the height of the thermal imager imaging sensor; M The lateral resolution of the thermal imager's pictures; K The vertical resolution of the thermal imager's pictures; r is the average of the shortest and longest distances between the thermal imager lens and the blade side; f is the focal length of the thermal imager; the coating thickness of each coating residual area is estimated based on the surface area and average temperature of each coating residual area, the physical properties of the coating material, the ambient temperature, the energy parameters of the hot air, and the time parameters when the thermal imager photographs the surface of the coating residual area. The calculation formula for the coating thickness of the coating residual area is:

[0044] ;

[0045] Where, d is the coating thickness of the current coating residual area; is the compensation coefficient of the current coating residual area; k is the thermal conductivity of the coating in the current coating residual area; t The cumulative time from the start of natural cooling of the blade to the current coating residue area being photographed by the thermal imager; The material density of the coating in the current coating residual area; c is the specific heat capacity of the coating in the current coating residual area; is the heating efficiency of hot air, ranging from 0.3 to 0.7; P The output power of the equipment providing hot air; The current coating residual area is t Average temperature at the time; The surrounding environment of the current coating residue area is t The temperature of the moment; It is the compensation adjustment amount of the current coating residual area;

[0046] Step S5: The laser cleaning head is mounted on a gantry-type five-degree-of-freedom drive mechanism. Based on the coating thickness and the material removal characteristic parameters of the laser cleaning head, offline programming is performed using PowerMill software to complete the trajectory planning for the laser cleaning operation of the coating residual area on the entire blade side.

[0047] Step S6: Laser clean the surface of the current blade according to the result of trajectory planning. After cleaning, perform quality inspection on the current blade. Remove the unclean blade from the surface coating as the blade to be cleaned, and complete the operations of steps S1 to S5 again.

[0048] like Figure 2 As shown, a laser processing device based on the laser removal method of ceramic coating on aero-engine turbine blades of the present invention is provided; the driving platform 2 and the shifting linear module 6 are both fixedly mounted on the control cabinet 1; a working head 4 is mounted at the end of the driving platform 2, and the working head 4 is a laser cleaning head; the sealing cover 3 is fixedly mounted on the control cabinet 1; the driving platform 2 and the shifting linear module 6 are both located in the sealing cover 3; the image acquisition module 5 is hoisted in the sealing cover 3; the clamping module 7 is fixedly mounted on the moving end of the shifting linear module 6; the clamping module 7 is used to clamp the blade 11 to be processed; the operating panel 8 is rotatably mounted on the side of the control cabinet 1; the ventilation filter 9 is fixedly mounted on the top of the sealing cover 3; and the hatch 10 is hinged on the side of the sealing cover 3.

[0049] like Figure 3 As shown, in the driving platform 2, there are two x-axis linear modules 202; each x-axis linear module 202 is fixedly connected to the control cabinet 1 through two pillars 201; both ends of the y-axis linear module 203 are fixedly connected to the moving end of an x-axis linear module 202; the z-axis linear module 204 is fixedly installed on the moving end of the y-axis linear module 203; the a-axis rotation module 205 is fixedly installed on the moving end of the z-axis linear module 204; the b-axis rotation module 206 is fixedly installed on the rotating end of the a-axis rotation module 205; The working head 4 is fixedly connected to the rotating end of the b-axis rotation module 206; in the image acquisition module 5, the hanging plate 501 is fixedly installed in the sealing cover 3; the first motor 502 is fixedly installed on the hanging plate 501; the first end of the cantilever 503 is fixedly installed on the output shaft of the first motor 502; the second end of the cantilever 503 is an elastic clip structure with screws, and the sliding shaft 504 is slidably installed in the elastic clip and tightened by screws; the infrared camera 505 is fixedly installed at the end of the sliding shaft 504; the infrared camera 505 uses a thermal imager.

[0050] like Figure 3 and Figure 4As shown, in the clamping module 7, the bracket 701 is fixedly connected to the moving end of the shift linear module 6; the second motor 702 is fixedly mounted on the bracket 701; the sliding sleeve 703 is fixedly mounted on the output shaft of the second motor 702; the middle part of the spindle 704 is rotatably connected to the bracket 701 through threaded cooperation; both ends of the spindle 704 are square shaft structures; the main cone block 706 is fixedly mounted on the square shaft at the first end of the spindle 704; the boss 709 is hinged on the square shaft at the first end of the spindle 704; the auxiliary cone block 705 is fixedly mounted on the square shaft at the second end of the spindle 704; the square shaft at the second end of the spindle 704 is inserted into the sliding sleeve 703 and is slidably connected to the sliding sleeve 703; the auxiliary cone block 705 is fixedly mounted on the square shaft at the second end of the spindle 704 The cone apex angle of the cone block 705 is greater than the cone apex angle of the main cone block 706; the middle circumferences of the two main connecting rods 708 are evenly hinged on the bracket 701; the middle circumferences of the two secondary connecting rods 707 are evenly hinged on the bracket 701; the root base of the blade 11 to be processed includes four positioning side surfaces and a positioning bottom surface; the first positioning side surface and the third positioning side surface of the root base of the blade 11 to be processed are tenon structures, and the surface of the tenon structure is a wavy curved surface; the second positioning side surface and the fourth positioning side surface of the root base of the blade 11 to be processed are positioning end surfaces, and the positioning end surfaces are planes; the positioning bottom surface of the root base of the blade 11 to be processed is a plane; the first end of the main connecting rod 708 is A cylindrical surface structure for clamping the tenon structure is provided; the second end of the main connecting rod 708 is provided with a spherical structure connected to the sliding point of the main cone block 706; the first end of the secondary connecting rod 707 is rotatably installed with a hollow stud 711 through threaded cooperation; a sliding rod 710 is slidably installed in the hollow stud 711; a clamping ball 713 is fixedly installed at the end of the sliding rod 710; a spring 712 is provided on the sliding rod 710, and the two ends of the spring 712 are respectively fixedly connected to the clamping ball 713 and the hollow stud 711; the clamping ball 713 is used to clamp the positioning end face of the root base of the blade 11 to be processed; the second end of the secondary connecting rod 707 is provided with a spherical structure connected to the sliding point of the secondary cone block 705 A spherical structure with point contact connection; the boss 709 is used to fit the positioning bottom surface of the root base of the blade to be processed 11; the rotation axis of the main connecting rod 708 on the bracket 701 is orthogonal to the rotation axis of the secondary connecting rod 707 on the bracket 701; four nozzles 714 are fixedly installed on the bracket 701 evenly distributed around the circumference, and a nozzle 714 is provided between every two adjacent main connecting rods 708 and secondary connecting rods 707; the first end of the nozzle 714 faces the blade to be processed 11; the hot air blower 715 is fixedly installed on the bracket 701; four air outlets 716 are provided on the hot air blower 715; each air outlet 716 is connected to the second end of a nozzle 714 through a pipeline.

[0051] Working principle of the present invention: When the laser processing equipment of the present invention is used, the hatch 10 should be opened first to clamp the blade to be processed, and the hatch 10 should be closed after the clamping is completed; for the clamping method, such as Figure 4As shown, the second motor 702 drives the spindle 704 to rotate forward, so that the auxiliary cone block 705 and the main cone block 706 move to the Figure 4 As shown in FIG, the lower side moves, at this time the distance between the first ends of the two main connecting rods 708 and the distance between the two clamping balls 713 are increased to allow the blade 11 to be processed to be placed in, and then the blade 11 to be processed is manually placed in, and the boss 709 supports the bottom, and then the second motor 702 drives the spindle 704 to reverse, so that the auxiliary cone block 705 and the main cone block 706 move to the left and right. Figure 4 As shown in the upper side movement, the main cone block 706 contacts the second ends of the two main connecting rods 708 and forces them to swing, so that the first ends of the two main connecting rods 708 gradually clamp the tenon structure of the blade to be processed 11; the secondary cone block 705 contacts the second ends of the two secondary connecting rods 707 and forces them to swing, so that the clamping balls 713 at the first ends of the two secondary connecting rods 707 gradually clamp the positioning end faces of the blade to be processed 11; in the above process, the main connecting rod 708 and the boss 709 mainly play a rigid clamping role for the blade to be processed, and the secondary connecting rod 707 mainly plays an initial positioning role for the blade to be processed; the structural design of the clamping module 7 enables the blade to be processed to be accurately centered and clamped; in particular, the setting of the slide rod 710 and the spring 712 is used to provide elastic supporting force, and the setting of the hollow stud 711 is used to adjust the initial spacing between the two clamping balls 713, or adjust the elastic supporting force after clamping the blade to be processed.

[0052] like Figure 3 As shown, the two side surfaces of the blade body described in step S1 are respectively the two surfaces of the blade to be processed 11 facing the shift linear module 6 and the two surfaces facing the hot air blower 715. Figure 3 In the embodiment, the side of the blade 11 to be processed facing the shift linear module 6 is the blade basin surface, and the side of the blade 11 to be processed facing the hot air blower 715 is the blade back surface; when using the laser processing equipment of the present invention, the shift linear module 6 is controlled by the operation panel 8 to drive the clamping module 7 to move to the position where the second motor 702 and the first motor 502 axes coincide with each other, corresponding to Figure 3The middle clamping module 7 moves to the left; then, the hot air blower 715 starts to preheat but does not blow air. At the same time, the first motor 502 drives the cantilever 503 to rotate to a position perpendicular to the shift linear module 6, and the infrared camera 505 is located on the side of the shift linear module 6; after the hot air blower 715 is preheated, it continues to blow 230°C hot air into the four nozzles 714 for 80 seconds. The nozzles 714 are thin-walled metal tubes that can be bent and deformed manually. In this embodiment, the first ends of the four nozzles 714 are all inclined upward at 45° to point to the blade 11 to be processed; wait for the hot air to stop After blowing, the blade is allowed to cool naturally for 30 seconds, and then the infrared camera 505 collects the surface temperature distribution map of the blade basin surface of the blade to be processed 11 facing the shift linear module 6, and then the cantilever 503 is driven to rotate 180° by the first motor 502, and then the infrared camera 505 collects the surface temperature distribution map of the blade back surface of the blade to be processed 11 facing the hot air blower 715. The time interval between the two surface temperature distribution map collections is 5 seconds; according to the different specifications of the blade to be processed 11, the clamping position of the sliding shaft 504 on the cantilever 503 can be manually adjusted in advance.

[0053] After collecting the surface temperature distribution map, steps S2 to S4 are performed, where r is approximately the distance from the thermal imager lens to the axis of the first motor 502; at the same time, the clamping module 7 is driven by the shift linear module 6 to move to the processing position on the lower side of the drive platform 2 and remain stationary; after completing step S5, the drive platform 2 drives the working head 4 to perform step S6, and finally completes the removal of the ceramic coating.

[0054] In particular, in this embodiment, the three side surfaces of the sealing cover 3 are hollowed out and transparent glass is embedded therein; the hatch 10 is hollowed out and transparent glass is embedded therein.

[0055] In particular, in this embodiment, a control system and a cooling system are provided in the control cabinet 1. The control system is used to relay the electrical connection between the operation panel 8 and the drive platform 2, the working head 4, the image acquisition module 5, the displacement linear module 6, the clamping module 7 and the ventilation filter 9; the cooling system is used to control the ambient temperature inside the sealing cover 3; the cooling system is also used to cool the working head 4.

[0056] In particular, in this embodiment, the ventilation filter 9 connects the inner and outer spaces of the sealing cover 3 , and the ventilation filter 9 has a built-in fan and a filter element, which are used for ventilation and air exchange while filtering out the smoke generated during processing in the sealing cover 3 .

[0057] In particular, the displacement linear module 6 , the x-axis linear module 202 , the y-axis linear module 203 and the z-axis linear module 204 may all adopt a linear motor or a ball screw structure driven by a motor.

[0058] In particular, the operation panel 8 is hinged to the first ends of two connecting rods that are connected in series and hinged to each other; the second ends of the two connecting rods that are connected in series and hinged to each other are hinged to the control cabinet 1 .

Claims

1. Laser removal method for ceramic coating of aircraft engine turbine blades, characterized in that: The following steps are involved: Step S1: A single blade is clamped and fixed, and hot air is continuously blown onto the blade surface from all sides of the blade. After the hot air stops blowing, the blade is allowed to cool naturally. The duration of natural cooling is the cooling time. When the cooling time expires, the surface temperature distribution of two sides of the blade body is photographed in sequence by a thermal imager. The two sides of the blade body are the blade basin curved surface and the blade back curved surface; Step S2: Save both surface temperature distribution maps as grayscale images. The pixel values in the grayscale images represent the temperature values at the pixel points. Perform edge detection on the grayscale images to obtain boundary lines of temperature mutations. A closed area enclosed by a boundary line that does not contain other boundary lines, or a closed area enclosed between two inner and outer nested boundary lines, is an isothermal area. Step S3: setting a threshold temperature, the isothermal area with an average temperature greater than or equal to the threshold temperature is the coating residual area, and the isothermal area with an average temperature less than the threshold temperature is the metal exposed area; Step S4: estimating the surface area of each coating residual area based on the imaging parameters of the thermal imager and the total number of pixels in each coating residual area; estimating the coating thickness of each coating residual area based on the surface area and average temperature of each coating residual area, the physical properties of the coating material, the ambient temperature, the energy parameters of the hot air, and the time parameter when the thermal imager photographs the surface of the coating residual area; Step S5: The laser cleaning head is mounted on a gantry-type five-degree-of-freedom drive mechanism, and based on the coating thickness and the material removal characteristic parameters of the laser cleaning head, trajectory planning for the laser cleaning operation of the coating residual area on the entire blade side is completed through offline programming; Step S6: Laser clean the surface of the current blade according to the result of trajectory planning. After cleaning, perform quality inspection on the current blade. Remove the unclean blade from the surface coating as the blade to be cleaned, and complete the operations of steps S1 to S5 again.

2. The method for laser removal of ceramic coatings from aircraft engine turbine blades according to claim 1, wherein: In step S1, the temperature of the hot air ranges from 200°C to 255°C; the time for continuously blowing the hot air is the heating time, which ranges from 30s to 120s; and the cooling time ranges from 10s to 60s.

3. The method for laser removal of ceramic coatings from aircraft engine turbine blades according to claim 2, wherein: In step S2, the edge detection process includes the following steps: Step S21: De-noising the grayscale image through Gaussian filtering; Step S22: using a histogram equalization algorithm to perform contrast enhancement on the denoised grayscale image; Step S23: Apply the Sobel algorithm or the Canny algorithm to perform edge detection on the grayscale image that has undergone contrast enhancement processing, and the identified edge line is the boundary line.

4. The method for laser removal of ceramic coatings from aircraft engine turbine blades according to claim 3, wherein: In step S3, the threshold temperature ranges from 100°C to 150°C.

5. The method for laser removal of ceramic coatings from aircraft engine turbine blades according to claim 4, wherein: In step S4, the surface area of the coating residual area is calculated as follows: ； Where, A is the surface area of the current coating residual area; is the surface curvature coefficient of the current coating residual area, ranging from 1 to 1.5; is the total number of pixels in the current coating residual area; W is the width of the thermal imager sensor; H is the height of the thermal imager imaging sensor; M The lateral resolution of the thermal imager's pictures; K The vertical resolution of the thermal imager's pictures; r is the average of the shortest and longest distances between the thermal imager lens and the blade side; f is the focal length of the thermal imager.

6. The method for laser removal of ceramic coatings from aircraft engine turbine blades according to claim 5, wherein: In step S4, the calculation formula for the coating thickness of the coating residual area is: ； Where, d is the coating thickness of the current coating residual area; is the compensation coefficient of the current coating residual area; k is the thermal conductivity of the coating in the current coating residual area; t The cumulative time from the start of natural cooling of the blade to the current coating residue area being photographed by the thermal imager; The material density of the coating in the current coating residual area; c is the specific heat capacity of the coating in the current coating residual area; is the heating efficiency of hot air, ranging from 0.3 to 0.7; P The output power of the equipment providing hot air; The current coating residual area is t Average temperature at the time; The surrounding environment of the current coating residue area is t The temperature of the moment; It is the compensation adjustment amount of the current coating residual area.

7. A laser processing device based on the laser removal method of ceramic coating on aero-engine turbine blades according to claim 6, comprising a control cabinet (1), a drive platform (2), a sealing cover (3), a working head (4), an image acquisition module (5), a displacement linear module (6), a clamping module (7), an operation panel (8), a ventilation filter (9), and a hatch (10), characterized in that: The driving platform (2) and the shifting linear module (6) are both fixedly mounted on the control cabinet (1); a working head (4) is mounted at the end of the driving platform (2), and the working head (4) is a laser cleaning head; the sealing cover (3) is fixedly mounted on the control cabinet (1); the driving platform (2) and the shifting linear module (6) are both located in the sealing cover (3); the image acquisition module (5) is hoisted in the sealing cover (3); the clamping module (7) is fixedly mounted on the moving end of the shifting linear module (6); the clamping module (7) is used to clamp the blade to be processed (11); the operation panel (8) is rotatably mounted on the side of the control cabinet (1); the ventilation filter (9) is fixedly mounted on the top of the sealing cover (3); and the hatch (10) is hinged on the side of the sealing cover (3).

8. The laser processing equipment according to claim 7, wherein: The driving platform (2) comprises a support (201), an x-axis linear module (202), a y-axis linear module (203), a z-axis linear module (204), an a-axis rotation module (205), and a b-axis rotation module (206); there are two x-axis linear modules (202); each x-axis linear module (202) is fixedly connected to the control cabinet (1) via two supports (201); both ends of the y-axis linear module (203) are fixedly connected to the movable end of an x-axis linear module (202); the z-axis linear module (204) is fixedly mounted on the movable end of the y-axis linear module (203); the a-axis rotation module (205) is fixedly mounted on the movable end of the z-axis linear module (204); the b-axis rotation module (206) is fixedly mounted on the rotation end of the a-axis rotation module (205); and the working head (4) is fixedly connected to the rotation end of the b-axis rotation module (206).

9. The laser processing equipment according to claim 8, wherein: The image acquisition module (5) comprises a hanging plate (501), a first motor (502), a cantilever (503), a sliding shaft (504), and an infrared camera (505); the hanging plate (501) is fixedly mounted in the sealing cover (3); the first motor (502) is fixedly mounted on the hanging plate (501); a first end of the cantilever (503) is fixedly mounted on the output shaft of the first motor (502); a second end of the cantilever (503) is an elastic clip structure fastened with screws, and the sliding shaft (504) is slidably mounted in the elastic clip and fastened by the screws; the infrared camera (505) is fixedly mounted on the end of the sliding shaft (504); and the infrared camera (505) is a thermal imager.

10. The laser processing equipment according to claim 9, wherein: The clamping module (7) includes a bracket (701), a second motor (702), a sliding sleeve (703), a spindle (704), a secondary cone block (705), a main cone block (706), a secondary connecting rod (707), a main connecting rod (708), a boss (709), a sliding rod (710), a hollow stud (711), a spring (712), a clamping ball (713), a nozzle (714), a hot air blower (715), and an air outlet (716); the bracket (701) is fixedly connected to the moving end of the displacement linear module (6); the second motor (702) is fixedly mounted on the bracket (701); the sliding sleeve (703) is fixedly mounted on the output shaft of the second motor (702); the middle part of the spindle (704) is connected to the bracket (701) The two ends of the spindle (704) are both square shaft structures; the main cone block (706) is fixedly mounted on the square shaft at the first end of the spindle (704); the boss (709) is hinged on the square shaft at the first end of the spindle (704); the auxiliary cone block (705) is fixedly mounted on the square shaft at the second end of the spindle (704); the square shaft at the second end of the spindle (704) is inserted into the sliding sleeve (703) and is slidably connected to the sliding sleeve (703); the cone apex angle of the auxiliary cone block (705) is greater than the cone apex angle of the main cone block (706); the middle circumferences of the two main connecting rods (708) are evenly hinged on the bracket (701); the middle circumferences of the two auxiliary connecting rods (707) are evenly hinged on the bracket (701); the blade to be processed (11 ) includes four positioning side surfaces and a positioning bottom surface; the first positioning side surface and the third positioning side surface of the root base of the blade to be processed (11) are tenon structures, and the tenon structure surface is a wavy curved surface; the second positioning side surface and the fourth positioning side surface of the root base of the blade to be processed (11) are positioning end surfaces, and the positioning end surfaces are planes; the positioning bottom surface of the root base of the blade to be processed (11) is a plane; the first end of the main connecting rod (708) is provided with a cylindrical surface structure for clamping the tenon structure; the second end of the main connecting rod (708) is provided with a spherical surface structure that is in contact with the main cone block (706) at a sliding point; the first end of the auxiliary connecting rod (707) is rotatably mounted with a hollow stud (711) through threaded engagement; the hollow stud (711) ) is slidably installed in the inner portion; a clamping ball (713) is fixedly installed at the end of the sliding rod (710); a spring (712) is sleeved on the sliding rod (710), and the two ends of the spring (712) are fixedly connected to the clamping ball (713) and the hollow stud (711) respectively; the clamping ball (713) is used to clamp the positioning end face of the root base of the blade to be processed (11); the second end of the secondary connecting rod (707) is provided with a spherical structure that is in contact with the sliding point of the secondary cone block (705); the boss (709) is used to fit the positioning bottom face of the root base of the blade to be processed (11); the rotation axis of the main connecting rod (708) on the bracket (701) is orthogonal to the rotation axis of the secondary connecting rod (707) on the bracket (701);Four nozzles (714) are fixedly mounted on the bracket (701) at a uniform distribution around the circumference, and a nozzle (714) is provided between every two adjacent main connecting rods (708) and auxiliary connecting rods (707); the first end of the nozzle (714) faces the blade (11) to be processed; the hot air blower (715) is fixedly mounted on the bracket (701); the hot air blower (715) is provided with four air outlets (716); each air outlet (716) is connected to the second end of a nozzle (714) through a pipeline.

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