Mirror milling machining and measurement-control process method, and system therefor

Abstract

A mirror milling machining and measurement and control process method, and a system therefor. A thin-walled-part machining path program migration process comprises: according to actual locating holes in point cloud data obtained by scanning a thin-walled part and theoretical locating holes on a theoretical triangular mesh curved surface generated on the basis of a design curved surface, aligning the theoretical triangular mesh curved surface and an actual triangular mesh curved surface corresponding to the point cloud data; for a plurality of cutter location points in a cutter location file, respectively calculating geodesic information of each cutter location point relative to the theoretical locating holes; and according to the geodesic information, migrating the cutter location points to the corresponding actual triangular mesh curved surface to form a migrated machining path. According to geodesic information, corresponding cutter location points are accurately mapped onto an actual machining curved surface of skinning data to form a migrated machining path, thereby reducing the impact of skin deformation on a tool path and improving the machining accuracy.

Description

Mirror milling machining and measurement and control process methods and systems Technical Field

[0001] This invention relates to the field of mirror milling technology, and specifically to a mirror milling machining and measurement control process method and system. Background Technology

[0002] Mirror milling is a machining method designed for large, thin-walled aircraft skins. Its main difference from traditional milling lies in the application of a support and measuring device to the back of the skin during the machining process. The milling cutter and the support and measuring device are aligned with the skin from both sides, and milling is performed synchronously. Compared to chemical etching milling used in traditional skin machining, it achieves better product uniformity.

[0003] Existing technologies already exist for milling thin-walled parts such as aircraft skin.

[0004] For example, Chinese patent CN201410532797.X discloses a method and equipment for mirror milling of aircraft skin. The equipment mainly includes a machine tool frame, a milling device, a vertical-to-horizontal conversion device, a lug clamping device, a flexible adsorption device, a top support device, a detection device, and a thickness measuring device. This invention improves the clamping efficiency of the skin by vertically clamping it using the vertical-to-horizontal conversion device. Combined with the vacuum adsorption device, it further improves the positioning accuracy of the skin, avoiding deformation caused by gravity. Based on in-machine detection using a laser displacement sensor, the actual curved surface of the skin part can be detected before processing, and the skin machining toolpath can be adjusted according to the actual clamping state to achieve adaptive CNC machining. The top support device can support the skin part from the reverse side during milling, avoiding machining chatter and improving machining stability. Online thickness monitoring is achieved during processing, providing thickness compensation. The integrated control system ensures the coordinated operation of all machine tool units, avoiding interference.

[0005] For example, Chinese patent CN201910811713.9 discloses a defect detection device for skin milling, relating to the field of skin processing, aiming to detect and locate defects in skin milling in real time. The device is used on a milling machine and includes: a PC, an infrared camera, a TOF depth camera, and a magnetic field motion module; the magnetic field motion module and the milling cutter are connected to the milling machine spindle via a milling chuck to transmit milling torque; during the skin milling process, the milling machine spindle drives the milling cutter and the magnetic field motion module to rotate, and the skin cuts the magnetic lines of force of the magnetic field motion module, generating motional eddy currents within it; the infrared camera is used to detect the temperature distribution on the skin surface; the TOF depth camera is used to reconstruct the three-dimensional shape of the skin; the PC is used to obtain and analyze a three-dimensional temperature distribution map based on the temperature distribution and the three-dimensional shape to detect internal defects in the skin.

[0006] However, in actual implementation, the inventors found that due to the physical characteristics of the thin-walled parts themselves, they are prone to certain deformations during processing, such as arching or sinking in the central area. This results in the curved surface of the thin-walled parts not being completely consistent with the designed curved surface and tool path during milling, which in turn affects the processing accuracy.

[0007] Summary of the Invention

[0008] In view of the above-mentioned problems in the prior art, a mirror milling machining and measurement and control process method is provided; on the other hand, a machining system for implementing the machining method is also provided.

[0009] The specific technical solution is as follows:

[0010] A mirror milling machining and measurement and control process method, comprising a thin-walled part clamping and transfer process, a thin-walled part measurement and point cloud acquisition process, a thin-walled part machining path program porting process, a thin-walled part machining path post-processing process, a thin-walled part machining and thickness measurement and control process, and a thin-walled part machining contour detection process;

[0011] The process of porting the machining path for thin-walled parts includes:

[0012] Based on the actual positioning holes in the point cloud data obtained from scanning the thin-walled part and the theoretical positioning holes on the theoretical triangular mesh surface generated based on the design surface, align the actual triangular mesh surface corresponding to the point cloud data with the theoretical triangular mesh surface.

[0013] For multiple tool positions in the tool position file, calculate the geodesic information between each tool position and the theoretical positioning hole;

[0014] Based on the geodesic information, the tool position point is transferred to the actual triangular mesh surface to form a transfer processing path.

[0015] On the other hand, during the clamping and transfer of the thin-walled part, a clamping fixture is used to clamp the thin-walled part. The clamping fixture includes a fixture frame, which is U-shaped, and multiple movable columns are distributed inside the fixture frame.

[0016] The tooling frame and the movable column are equipped with grippers, which clamp and fix the thin-walled part.

[0017] The tooling frame also contains multiple top support devices, which move from the back of the thin-walled component to the front to support it.

[0018] On the other hand, the thin-walled part clamping and transfer process includes:

[0019] The thin-walled component is hoisted into the tooling frame, and a laser projection is projected onto the tooling frame;

[0020] The thin-walled component is located within the coverage area of ​​the laser projection;

[0021] The top support device and the gripper are adjusted according to the laser projection and tooling program to adjust the thin-walled part to the predetermined processing state;

[0022] The thin-walled components are clamped sequentially, and then scanned to obtain the point cloud data.

[0023] On the other hand, during the measurement and point cloud acquisition process of the thin-walled component, the thin-walled component is scanned and the point cloud data is constructed by a machine tool driven line laser.

[0024] On the other hand, the process of extracting tool positions from the tool position file includes:

[0025] The theoretical positioning hole center coordinates are extracted from the theoretical triangular mesh surface, and the tool position information of each tool position is extracted from the tool position file.

[0026] The tool position information includes the tool position coordinates;

[0027] For each tool position point, the tool position point is projected onto the theoretical mesh surface of the theoretical triangular mesh surface to generate a first projection point and the projection length between the first projection point and the coordinates of the tool position point;

[0028] Calculate the area coordinates of the first projection point relative to the grid of projection points it belongs to. For each theoretical positioning hole center coordinate, calculate the geodesic length relative to the area coordinates to serve as the geodesic information.

[0029] On the other hand, the path transplantation process that forms the transplantation processing path includes:

[0030] The actual positioning hole center coordinates of the actual positioning hole are extracted from the point cloud data, and the tool position point is projected onto the actual grid surface corresponding to the point cloud data to obtain a second projection point.

[0031] The length of the pre-projected geodesic line relative to the actual positioning hole center coordinates of the second projection point is calculated, and then the geodesic line deviation value is obtained by processing the geodesic line information and the pre-projected geodesic line length.

[0032] The second projection point is iterated according to the geodesic deviation value and the preset geodesic deviation range until the geodesic deviation range is met, and then it is used as the actual transplant point.

[0033] The transplantation processing path is generated based on the actual transplantation point.

[0034] On the other hand, the post-processing of the thin-walled part machining path includes generating a new transplant tool position file according to the transplant machining path, and performing simulation verification on the transplant tool position file.

[0035] During the machining and thickness measurement and control of the thin-walled part, the transplanted tool position file is used to machine the thin-walled part.

[0036] On the other hand, during the processing and thickness measurement and control of the thin-walled part, the supporting device is also used to support the sunken area of ​​the thin-walled part.

[0037] On the other hand, during the processing and thickness measurement and control of the thin-walled part, an ultrasonic probe is used to measure the thickness of the thin-walled part in real time to obtain the real-time thickness of the thin-walled part. The real-time thickness is used to control the mirror milling process of the thin-walled part.

[0038] On the other hand, the ultrasonic probe has multiple eddy current sensors distributed circumferentially. The eddy current sensors are used to generate eddy currents during the measurement process of the ultrasonic probe to measure the eddy current spacing of the ultrasonic probe relative to the thin-walled member.

[0039] During the mirror milling process, the distance between the ultrasonic probe and the thin-walled part is also controlled based on the eddy current spacing.

[0040] On the other hand, during the measurement process of the ultrasonic probe, the ultrasonic probe is controlled to point towards the back normal of the thin-walled component by an eddy current normal holding process.

[0041] The eddy current normal holding process includes:

[0042] Obtain the distances of multiple eddy current sensors relative to the back surface of the thin-walled component;

[0043] A machine tool coordinate system is constructed based on the eddy current distribution generated by the eddy current sensor, and the back surface distance is transferred into the machine tool coordinate system respectively;

[0044] The distribution center of the eddy current coincides with the origin of the machine tool coordinate system;

[0045] The eddy current normal vector is calculated in the machine tool coordinate system according to the back face distance obtained by transplantation;

[0046] The orientation of the ultrasonic probe is adjusted based on the eddy current normal vector so that the eddy current normal vector coincides with the back normal vector of the thin-walled component.

[0047] On the other hand, the ultrasonic probe is a water immersion ultrasonic probe, and a nozzle is provided on the outside of the coupling part of the ultrasonic probe. The nozzle is used to output water flow filling the area between the coupling part and the thin-walled member during the measurement process of the ultrasonic probe.

[0048] The nozzle is equipped with a water pressure sensor in front of it and collects real-time water pressure values. During the mirror milling process, the real-time water pressure value is compared with the water pressure standard value to adjust the water flow pressure and support the thin-walled part through water pressure.

[0049] On the other hand, the thin-walled part machining contour detection process includes:

[0050] The processed thin-walled part is scanned to obtain the processed point cloud data, and a processed scanned surface is generated according to the processed point cloud data;

[0051] The feature regions in the designed surface are identified to obtain the boundaries of the feature regions;

[0052] The boundary of the feature region is projected onto the processed scanned surface, and then geodesic verification is performed on the first feature point in the boundary of the feature region and the second feature point on the processed scanned surface.

[0053] A machining system for implementing the above-described mirror milling and measurement and control process.

[0054] On the other hand, the processing system includes a clamping fixture for holding thin-walled parts;

[0055] The clamping fixture is equipped with a top support device, which is used to move synchronously with the milling cutter during mirror milling to support the thin-walled part.

[0056] An ultrasonic probe is provided on the top of the top support device. The ultrasonic probe is used to measure the thickness from the back of the thin-walled part during the mirror milling process.

[0057] An eddy current sensor is provided circumferentially on the ultrasonic probe, and the processing system controls the ultrasonic probe to maintain a constant normal and spacing relative to the thin-walled part according to the eddy current sensor.

[0058] A nozzle is provided on the outer side of the coupling part of the ultrasonic probe. The nozzle is used to output water flow that fills the area between the coupling part and the thin-walled member during the measurement process of the ultrasonic probe.

[0059] The nozzle is equipped with a water pressure sensor that collects real-time water pressure values. During the mirror milling process, the pressure of the water flow is adjusted by comparing the real-time water pressure value with the standard water pressure value.

[0060] The above technical solution has the following advantages or beneficial effects:

[0061] To address the issue that existing skin machining methods are prone to affecting machining accuracy due to skin deformation during actual processing, this solution employs laser scanning to obtain point cloud data after clamping the thin-walled part. Simultaneously, positioning holes are added during the pre-machining and design processes of the thin-walled part. Based on this, geodesic information between the tool position point and the theoretical positioning holes on the design surface is obtained by projecting the tool position point onto the design surface. Subsequently, the corresponding tool position point can be accurately mapped onto the actual machining surface of the point cloud data according to the geodesic information to form a transfer machining path, reducing the impact of skin deformation on the toolpath and improving machining accuracy. Attached Figure Description

[0062] Embodiments of the invention will be described more fully with reference to the accompanying drawings. However, the drawings are for illustration and explanation only and do not constitute a limitation on the scope of the invention.

[0063] Figure 1 is an overall schematic diagram of an embodiment of the present invention;

[0064] Figure 2 is a schematic diagram of the program transfer process for the thin-walled part processing path in an embodiment of the present invention;

[0065] Figure 3 is a simplified diagram of the mirror milling system in an embodiment of the present invention;

[0066] Figure 4 is a schematic diagram of the clamping fixture in an embodiment of the present invention;

[0067] Figure 5 is a schematic diagram of the point cloud acquisition process in an embodiment of the present invention;

[0068] Figure 6 is a schematic diagram of the knife site extraction process in an embodiment of the present invention;

[0069] Figure 7 is a schematic diagram of the geodesic calculation process in an embodiment of the present invention;

[0070] Figure 8 is a schematic diagram of the path migration process in an embodiment of the present invention;

[0071] Figure 9 is a schematic diagram of the eddy current normal holding process in an embodiment of the present invention;

[0072] Figure 10 is a schematic diagram of the nozzle in an embodiment of the present invention;

[0073] Figure 11 is a schematic diagram of the water supply system in an embodiment of the present invention;

[0074] Figure 12 is a schematic diagram of the thin-walled part machining contour detection process in an embodiment of the present invention;

[0075] Figure 13 is a schematic diagram of the processing system in an embodiment of the present invention. Detailed Implementation

[0076] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0078] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0079] This invention includes:

[0080] A mirror milling machining and measurement and control process method, as shown in Figure 1, includes the following sequential processes: thin-walled part clamping and transfer process, thin-walled part measurement and point cloud acquisition process, thin-walled part machining path program porting process, thin-walled part machining path post-processing process, thin-walled part machining and thickness measurement and control process, and thin-walled part machining contour detection process.

[0081] As shown in Figure 2, the process of porting the machining path program for thin-walled parts includes:

[0082] Based on the actual positioning holes in the point cloud data obtained from scanning the thin-walled part and the theoretical positioning holes on the theoretical triangular mesh surface generated based on the design surface, align the actual triangular mesh surface corresponding to the point cloud data with the theoretical triangular mesh surface.

[0083] For multiple tool positions in the tool position file, calculate the geodesic information between each tool position and the theoretical positioning hole;

[0084] Based on the geodesic information, the tool position point is transferred to the corresponding actual triangular mesh surface to form a transfer processing path.

[0085] Specifically, addressing the issue that existing mirror milling methods are prone to affecting machining accuracy due to deformation of thin-walled parts during actual processing, this embodiment improves the toolpath transfer process for thin-walled parts. Multiple positioning holes are pre-drilled on the thin-walled part using flanging or other equivalent processes. Corresponding positioning holes also exist on the design surface in the thin-walled part's design program. For distinction, the positioning holes on the design surface are called theoretical positioning holes, while the actual positioning holes on the thin-walled part are called actual positioning holes; they are one-to-one correspondences. Typically, four positioning holes are located at the four corners of the outer perimeter of the machined body of the thin-walled part, but the number and position may vary depending on the type of thin-walled part.

[0086] Before toolpath transplantation, multiple tool position points can be extracted from the toolpath file obtained after toolpath design. These tool position points correspond to the tool positions used during machining to mill the thin-walled part to match the designed curved surface. To achieve a more accurate tool position transplantation process, the positioning holes on the designed curved surface are used as references beforehand. The geodesic information between each tool position point and the positioning hole is calculated. Then, based on this geodesic information, the tool position points can be mapped onto the measured point cloud data with reference to the actual positioning hole positions, thus achieving a more accurate transplantation process.

[0087] Point cloud data refers to the data obtained by scanning a thin-walled part after it has been clamped. Because thin-walled parts have a certain degree of flexibility, they need to be clamped and supported to a predetermined processing state beforehand. Then, a corresponding scanning device, such as a line laser scanner, is used to scan the entire curved surface of the thin-walled part, and the returned laser point cloud data is collected and used as point cloud data. This point cloud data includes the positional information of each point on the thin-walled part in three-dimensional space. Further analysis of the point cloud can easily extract holes on the thin-walled part, such as actual positioning holes.

[0088] Based on the above-described migration process, the tool positions in the toolpath file can be migrated one by one to the actual curved surface of the thin-walled part. Further processing is then performed using toolpath information, such as toolpath normal, sequence, and row number, to obtain the corresponding migration machining path. Based on this migration machining path, in the subsequent mirror milling process, the milling cutter's machining and the movement of the support and measuring devices are controlled according to the corresponding mirror milling flow, thereby achieving better machining results.

[0089] In practice, the above-mentioned machining method mainly relies on a specific mirror milling system. This mirror milling system includes a corresponding multi-axis machining center, a support device that matches the milling cutter and can move synchronously, and a measuring device. Figure 3 shows a typical mirror milling system, including a spindle component A001 for milling thin-walled parts, a scanning device A002 for acquiring the curved surface of the thin-walled parts, a support device A003, a measuring device A004, and a computer device A005. The computer device A005 may be the machine tool's control system or other equivalent equipment, which is equipped with specific computer programs to implement the corresponding functions, particularly the aforementioned machining method.

[0090] To achieve better measurement results, the measuring device can be positioned at the end of the support device and move synchronously with it. For example, the measuring device can be an ultrasonic probe, located at the end of the support device, which measures the real-time thickness of the thin-walled part from the back when the support device lifts it up. This, in conjunction with the milling cutter on the front, allows for precise judgment of the current milling status of the thin-walled part and whether the thickness meets the actual processing requirements.

[0091] Before actual measurement begins, the thin-walled part should have undergone appropriate pretreatment processes, including heat treatment, cold rolling, stretching, roughing or other equivalent processing steps, so that the thin-walled part can be milled into shape.

[0092] Furthermore, prior to actual machining, corresponding design work should be carried out for thin-walled parts, including designing the desired thin-walled part surfaces, such as skin surfaces, using 3D design software to obtain the design surface. This design surface is actually represented as a computer program model file, which can be read and displayed by specific 3D industrial design software, and the corresponding machining drawings can be exported as needed.

[0093] The toolpath file, designed based on the machining parameters of the mirror milling system after determining the raw material parameters and design surface of the thin-walled part, includes a feasible machining scheme. This scheme comprises the tool positions required to mill the thin-walled part to match the design surface, the trajectory of these tool positions, and corresponding tool information such as the tool normal, row number, and spindle speed. The toolpath file is in a specific format, such as CLS / APT, and can be read and executed by CNC equipment for machining the workpiece. However, in the scenario addressed by this invention, directly generated toolpath files often exhibit a certain offset in three-dimensional space between the actual machining tool positions and the desired tool positions due to factors such as the clamping accuracy of the thin-walled part and material deformation. Therefore, this invention involves a process of remapping the tool positions onto the actual machining surface. After this process, a corrected toolpath file is generated, and a more accurate milling process is then performed based on this file.

[0094] It is important to note that the tool position transfer process should be carried out after the thin-walled part is initially clamped and scanned, and then directly used to mill the thin-walled part after the transfer is completed, so as to avoid introducing new offsets into the thin-walled part during repeated clamping.

[0095] In one embodiment, during the clamping process, the clamping fixture shown in FIG4 is used to clamp the thin-walled part. The clamping fixture includes a fixture frame 101, which is U-shaped, and multiple movable columns 102 are distributed inside the fixture frame 101.

[0096] The tooling frame 101 and the movable column 102 are equipped with grippers 103, which clamp and fix the thin-walled parts.

[0097] Multiple top support devices 104 are also distributed inside the tooling frame 101. The top support devices 104 move from the back of the thin-walled part to the front to support the thin-walled part.

[0098] Specifically, to achieve a better fixing effect, in this embodiment, the thin-walled part is pre-clamped using the aforementioned clamping fixture before scanning. The clamping fixture includes a U-shaped fixture frame 101, which has a hollow frame structure and two sides. When clamping the thin-walled part, the fixture frame 101 is placed with its front side facing upwards, and the movable column 102 and the top support device 104 are located on the side near the back of the fixture frame 101. Multiple grippers 103 are distributed circumferentially on the fixture frame 101 for clamping and fixing the thin-walled part circumferentially.

[0099] Since the thin-walled part itself may be an irregular structure with raised edges in three-dimensional space, an additional gripper 103 is provided in the tooling frame 101 via a movable column 102. Multiple guide rails are distributed on the side of the tooling frame 101 near the back. The movable column 102 is movably mounted on the tooling frame 101 via the guide rails and its position can be adjusted as needed so that the gripper 103 can effectively clamp the raised edges.

[0100] In addition, to maintain the shape of the thin-walled part, a plurality of support devices 104 are distributed in the tooling frame 101. The support devices 104 are used to support the back of the thin-walled part according to the set support program, thereby maintaining the thin-walled part in a specific bending state to facilitate subsequent scanning, measurement, milling and other operations.

[0101] To achieve a better supporting effect, multiple supporting devices 104 can be distributed in a rectangular shape inside the rectangular tooling frame 101, and their supporting height can be controlled respectively to achieve support and shape preservation of the thin-walled part.

[0102] Similarly, the number of the aforementioned grippers 103 and movable columns 102 can also be adjusted by disassembling, installing, positioning, and angle according to the shape, specifications, and other parameters of the thin-walled parts being processed.

[0103] In one embodiment, as shown in Figure 5, the thin-walled part clamping and transfer process includes:

[0104] The thin-walled component is hoisted into the tooling frame, and a laser projection is projected onto the tooling frame;

[0105] The thin-walled component is located within the coverage area of ​​the laser projection;

[0106] Adjust the top support device and grippers according to the laser projection and tooling program to adjust the thin-walled part to the predetermined processing state;

[0107] The thin-walled parts are clamped sequentially, and then scanned to obtain point cloud data.

[0108] Specifically, this process can be used to clamp and scan the aforementioned fixture to obtain more accurate point cloud data.

[0109] Specifically, before hoisting the thin-walled component, a corresponding support program was pre-programmed around the design surface. This program included the support parameters required to support the thin-walled component to the predetermined processing state. The program was then matrixed based on the actual number of support devices on the tooling frame to generate matrix point elements. Subsequently, a corresponding tooling program was generated to control the support devices.

[0110] Furthermore, laser projection assistance was introduced during the clamping process of thin-walled parts, thereby achieving a better clamping indication process. This laser projection assistance is achieved through a laser projector, which projects laser patterns onto the surface of the object to indicate various positions during the clamping process, including the correct position of the edge of the thin-walled part, the clamping position of the jaws on the thin-walled part, and so on.

[0111] To achieve this process, laser projection programming is required beforehand. This includes planning the front of the tooling frame and determining the positioning markers that the laser projection relies on during the projection process, such as the positioning markers of the tooling frame and the actual positioning holes of the thin-walled parts. Based on the determined relative reference objects, the corresponding clamping lines are further planned and laser projection programming is performed through the Projector, converting them into corresponding laser projection programming files for subsequent use.

[0112] After completing the preliminary preparations, the thin-walled component can be hoisted. Specifically, this involves placing the fixture frame horizontally, then hoisting the thin-walled component above the fixture frame and lowering it. During this process, the height of the support device is pre-adjusted using the fixture program. After the thin-walled component is lowered, the laser projector is controlled based on the laser projection programming file to project the component. Specifically, the center mark of the laser projection is first aligned with the target point on the surface of the thin-walled component or the fixture frame. Then, the actual positioning holes of the thin-walled component are projected, and the orientation of the thin-walled component and the height of the support device are fine-tuned according to the projection position until the actual positioning holes coincide with the projected positioning hole marks. This indicates that the thin-walled component has reached the predetermined processing state and can be clamped. During clamping, the corresponding construction specifications should be followed to clamp the jaws sequentially, avoiding applying additional stress to the thin-walled component.

[0113] Finally, after the thin-walled part is clamped, the process transitions to the measurement and point cloud acquisition of the thin-walled part, where scanning is performed to obtain point cloud data. In one embodiment, a line laser is used as the scanning method. Specifically, a line laser scanning program capable of completely scanning the design surface is pre-built in the same coordinate system as the design surface. Subsequently, the entire front surface of the thin-walled part is scanned by the line laser driven by the machine tool, and the reflected signals are collected as scanning data. Based on this scanning data, combined with the kinematic algorithm of the machine tool, reconstruction is performed, and the spatial point cloud data corresponding to the surface of the thin-walled part is easily obtained as the point cloud data output.

[0114] In one embodiment, during the processing and thickness measurement of thin-walled parts, a support device is used to support the sunken area of ​​the thin-walled parts.

[0115] Specifically, after selecting the aforementioned clamping fixture for clamping, to achieve better milling accuracy, after scanning the thin-walled part, the fixture frame used during scanning can be directly flipped and transferred to the machining position for subsequent milling. At this time, the support device is connected to the mirror milling system and moves synchronously with the milling cutter on the front during machining to support the sunken area of ​​the thin-walled part during machining, thereby achieving better machining results.

[0116] In one embodiment, as shown in Figure 6, the process of extracting tool position points calculated from the tool position file includes:

[0117] The theoretical positioning hole center coordinates are extracted from the design surface, and the tool position information of each tool position is extracted from the tool position file.

[0118] Tool position information includes tool position coordinates;

[0119] For each tool position point, the tool position point is projected onto the theoretical mesh surface of the design surface to generate the first projection point and the projection length between the first projection point and the tool position point coordinates;

[0120] Calculate the area coordinates of the first projection point relative to its grid, and calculate the geodesic length relative to the area coordinates for the center coordinates of each theoretical positioning hole, as geodesic information.

[0121] Specifically, after obtaining the design surface and tool position files, the geodesic information of each tool position point relative to the theoretical positioning hole coordinates can be obtained through the above process, which serves as a reference for subsequent tool position point transplantation.

[0122] For the designed curved surface, a point cloud of the designed surface can be pre-generated through discretization at equal intervals, thereby constructing a point cloud data similar to the original point cloud data. The spacing can be selected based on the scanning interval of the line laser. The discretization process includes obtaining the parameter range of the designed surface, parameterizing the surface, and then changing the UV values ​​on the UV surface according to the spacing to obtain multiple points, which are then added to the point cloud of the designed surface. Subsequently, by combining the positions of predetermined theoretical positioning holes in the designed surface, the center coordinates of the theoretical positioning holes on the designed surface can be easily extracted. Combined with the point cloud of the designed surface, the center coordinates of the theoretical positioning holes after point cloudification can be extracted. This process allows the center coordinates of the theoretical positioning holes to be adjusted to match the coordinates of the point cloud data, facilitating subsequent alignment with the actual positioning holes in the point cloud data.

[0123] Furthermore, for the toolpath file, multiple toolpoints can be obtained by repeatedly reading the file. The toolpoint information mainly includes the toolpoint coordinates, normal, and row number. During the porting process, the main focus is on the spatial positional changes of the mapped toolpoints due to the deformation of the thin-walled part, i.e., the migration of the toolpoint coordinates.

[0124] To achieve better processing efficiency, in this embodiment, the point cloud data of the design surface and the point cloud data obtained from scanning are respectively meshed. In one embodiment, the Delaunay triangulation algorithm is used to mesh the design surface and the point cloud data respectively. The meshed surface after meshing the design surface is called the theoretical mesh surface, and the meshed surface after meshing the point cloud data is called the actual mesh surface.

[0125] Then, for the theoretical mesh surface, the tool point is first projected onto the theoretical mesh surface along the surface normal, which will inevitably fall into a triangular mesh on the theoretical mesh surface. At this time, the projection length between the projection point and the tool point, as well as the triangular mesh in which the projection point is located, are recorded as the projection point mesh. Inside the projection point mesh, for each projection point, a vertex of the projection point mesh is connected, resulting in multiple mesh sub-cells within the projection point mesh. In the triangular mesh, there are three mesh sub-cells. The area coordinates of the mesh sub-cells are calculated. The geodesic length of the projection point relative to one of the theoretical positioning holes can be obtained by interpolating the geodesic lengths from the positioning hole coordinates to the three vertices with the area coordinates. Finally, the geodesic lengths of the projection points relative to each theoretical positioning hole are summarized to obtain complete geodesic information, which is convenient for subsequent tool point transplantation.

[0126] Specifically, referring to Figure 7, in a triangular mesh with three vertices A, B, and C, there are three mesh sub-units with the center position being the projection point p. The area coordinates of the mesh sub-units are S1, S2, and S3, respectively, and they satisfy S1+S2+S3=1. Then, the geodesic length d between the external theoretical positioning hole pos and the projection point is d=d1*S1+d2*S2+d3*S3.

[0127] In one embodiment, as shown in Figure 8, the path migration process for forming the migration processing path includes:

[0128] The actual positioning hole center coordinates are extracted from the point cloud data, and the tool position point is projected onto the actual grid surface corresponding to the point cloud data to obtain the second projection point.

[0129] The length of the pre-projected geodesic line relative to the actual center coordinates of the positioning hole is calculated for the second projection point. Then, the geodesic line deviation value is obtained by processing the geodesic line information and the pre-projected geodesic line length.

[0130] The second projection point is iterated according to the geodesic deviation value and the preset geodesic deviation range until the geodesic deviation range is met, and then it is used as the actual transplant point.

[0131] Generate a transplantation processing path based on the actual transplantation site.

[0132] Specifically, after determining the aforementioned geodesic information, the tool position point can be migrated to the point cloud data based on the geodesic information.

[0133] For the point cloud data, since it has been pre-scanned with a line laser, point cloud data associated with the actual positioning hole has been extracted. At this point, the point cloud can be identified using a boundary recognition algorithm to obtain the edge portion of the point cloud data, and the hole portion in the edge can be obtained by combining it with curvature recognition. By fitting the point cloud data of this portion, the center coordinates of the actual positioning hole can be obtained.

[0134] Similarly, following the above meshing process, the actual mesh surface has been obtained in advance. For the actual mesh surface, the tool point is first projected onto the actual mesh surface along the surface normal, which will inevitably fall into a triangular mesh on the actual mesh surface.

[0135] At this point, the projected length between the pre-projection point and the tool position point, as well as the triangular mesh containing the pre-projection point, are recorded as the projection mesh. Inside the projection mesh, for each pre-projection point, a connection is made to the vertices of the projection mesh, resulting in multiple mesh sub-cells within the pre-projection point mesh. In the triangular projection mesh, there are three mesh sub-cells. The area coordinates are calculated for each mesh sub-cell. The geodesic length from the tool position point to the pre-projection point can then be obtained by interpolating the geodesic lengths from the tool position point to the three vertices with the area coordinates. Finally, combining the positional information of the pre-projection point mesh with its relative positional relationship to the actual positioning hole, the pre-projected geodesic length is obtained.

[0136] Based on the length of the pre-projected geodesic line, it can be compared with the geodesic information collected in advance to determine whether the position of the pre-projected point relative to the actual positioning hole meets the expected projection. That is, it is determined whether the difference between the length of the pre-projected geodesic line and the geodesic information is within the geodesic deviation range. If not, the position of the pre-projected point is shifted through the optimization algorithm until it enters the geodesic deviation range, and then it is used as the actual projection point.

[0137] Then, based on the normals of the surrounding mesh points associated with the actual transplant point on the actual mesh surface, the normal of the actual transplant point on the actual mesh surface is calculated using an interpolation fitting method. The actual transplant point on the actual mesh surface is then offset along its normal by its corresponding projection length to obtain the actual transplanted point position. Based on this actual transplant point and the adjusted normal, the transplant machining trajectory can be obtained for subsequent mirror milling processes.

[0138] In one embodiment, during the processing and thickness measurement of thin-walled parts, an ultrasonic probe is used to measure the thickness of the thin-walled parts in real time to obtain the real-time thickness of the thin-walled parts. The real-time thickness is used to control the mirror milling process of the thin-walled parts.

[0139] Specifically, to achieve a more accurate milling process, in this embodiment, during mirror milling, an ultrasonic probe is used to measure the thickness of the thin-walled part in real time to obtain the real-time thickness of the thin-walled part, which is used to provide closed-loop control for the mirror milling system. Specifically, to achieve better machining results, the mirror milling system will configure a support device on the back of the thin-walled part during machining to support and maintain its shape. During the movement of the milling cutter, the support device will move synchronously with the milling cutter. In this system, the ultrasonic probe can be optionally placed at the top of the support device to achieve a more accurate thickness measurement of the cutting area of ​​the milling cutter. During the measurement process, the coupling agent can be adjusted according to the measurement requirements. In one embodiment, the coupling agent is water injected between the ultrasonic probe and the thin-walled part through a nozzle.

[0140] In one embodiment, the ultrasonic probe has multiple eddy current sensors distributed circumferentially. The eddy current sensors are used to generate eddy currents during the measurement process of the ultrasonic probe to measure the eddy current spacing between the ultrasonic probe and the thin-walled component.

[0141] During the mirror milling process, the distance between the ultrasonic probe and the thin-walled part is also controlled based on the eddy current spacing.

[0142] Specifically, to achieve better measurement results, the spacing between the transducer array and the thin-walled component of the ultrasonic probe needs to be controlled so that the gap is filled with coupling agent, but the coupling agent is not too thick to ensure measurement accuracy.

[0143] In this embodiment, the ultrasonic probe has been modified by installing multiple eddy current sensors in the circumferential direction of the ultrasonic probe. These sensors can generate corresponding eddy currents in the direction the ultrasonic probe is pointing and collect echo signals. Based on the intensity of the echo signals and a pre-calibrated reflection intensity-distance comparison function, the eddy current spacing between the ultrasonic probe and the thin-walled part can be easily calculated and used as the machine tool control parameters of the mirror milling system to achieve closed-loop control of the milling cutter's cutting process.

[0144] As an optional implementation, four eddy current sensors are evenly distributed at the 12, 3, 6, and 9 o'clock positions on the ultrasonic probe.

[0145] Furthermore, to achieve the aforementioned spacing control process, the relationship between eddy current intensity and spacing needs to be calibrated before processing. The calibration process includes:

[0146] A metal calibration block is pre-introduced. The normal of the eddy current sensor is then aligned with the surface of the metal calibration block, maintaining a certain gap, which serves as the zero-point gap. Eddy current values ​​are then read and associated with the zero-point position for storage. Based on this, the eddy current sensor is moved along the normal in specific steps to increase the gap, and eddy current values ​​are recorded and stored. By performing linear fitting on the collected distances and eddy current values, the reflection intensity-distance correlation function can be easily obtained.

[0147] In one embodiment, during the measurement process of the ultrasonic probe, the ultrasonic probe is controlled to point towards the back normal of the thin-walled component by an eddy current normal holding process.

[0148] As shown in Figure 9, the eddy current normal-maintaining process includes:

[0149] Obtain the distance between multiple eddy current sensors and the back surface of the thin-walled component;

[0150] A machine tool coordinate system is constructed based on the eddy current distribution generated by the eddy current probe, and the back face distance is mapped in the machine tool coordinate system respectively;

[0151] The distribution center of the eddy currents coincides with the origin of the machine tool coordinate system;

[0152] The eddy current normal vector is calculated in the machine tool coordinate system based on the back face distance obtained by mapping.

[0153] The orientation of the ultrasonic probe is adjusted based on the eddy current normal vector so that the eddy current normal vector coincides with the back normal vector of the thin-walled component.

[0154] Specifically, to achieve better measurement results, in this embodiment, the ultrasonic probe is kept aligned with the back normal of the thin-walled component by utilizing the feedback signal from the eddy current sensor. In this embodiment, the ultrasonic probe and eddy current sensor are mounted on a ball joint, allowing their orientation to be freely changed.

[0155] After obtaining the real-time thickness using eddy currents, the distances of multiple eddy current sensors relative to the back surface of the thin-walled part can be obtained according to this process. Then, three of the eddy current sensors are selected, and a machine tool coordinate system is established based on the distribution surface of the eddy currents they generate. This machine tool coordinate system has the distribution centers of the three eddy currents as its origin, and the measurement distances of the three eddy current sensors are mapped to the machine tool coordinate system.

[0156] Then, calculate the eddy current normal vector between the three eddy currents, which is: n = n1 × n2.

[0157] In the formula, n1 represents the vector of the first eddy current and the second eddy current, with the direction from the second eddy current to the first eddy current; n2 represents the vector of the first eddy current and the third eddy current, with the direction from the third eddy current to the first eddy current; n represents the eddy current normal vector of the first eddy current, with the direction being the cross product of vectors n1 and n2. The calculation process follows the right-hand rule.

[0158] Based on the above process, the eddy current normal vector can be obtained. The back side of the thin-walled part has a predetermined theoretical normal vector (0, 0, 1) in the machine tool coordinate system. For these two vectors, the vector angle between them can be easily calculated, which corresponds to the deviation angle of the ultrasonic probe. Then, the spherical joint is rotated based on the deviation angle to make the two vectors coincide, thus completing the normal control process of the ultrasonic probe.

[0159] In one embodiment, the ultrasonic probe is a water immersion ultrasonic probe, and a nozzle is provided on the outer side of the coupling part of the ultrasonic probe. The nozzle is used to output water flow filling the area between the coupling part and the thin-walled component during the measurement process of the ultrasonic probe.

[0160] The nozzle is equipped with a water pressure sensor that collects real-time water pressure values. During the mirror milling process, the water pressure is adjusted by comparing the real-time water pressure value with the standard water pressure value.

[0161] Specifically, to achieve better measurement results, in this embodiment, a water immersion ultrasonic probe is selected. A nozzle is arranged around the ultrasonic probe to output water flow filling the area between the coupling part and the thin-walled component during the measurement process. As shown in Figure 10, the nozzle 201 is roughly U-shaped, with the water immersion ultrasonic probe 202 located at its central bottom. An outlet is arranged around the water immersion ultrasonic probe 202, from which the coupling agent flows and fills the U-shaped structure. An eddy current sensor 203 for distance measurement is also arranged on the outside of the nozzle 201. The nozzle 201 is spaced apart from the thin-walled component 204.

[0162] Furthermore, the water pressure generated by the nozzle 201 is also used to support the thin-walled component.

[0163] In addition, as shown in Figure 11, the pre-stage of the nozzle includes a series of water supply systems, including a water tank 301 as a water source, a water pump 302 that provides water flow, a defoaming device 303 that defoams the water flow output by the water pump 302, and a fluid valve 304 that outputs water flow to the nozzle 201.

[0164] During thickness measurement, water pump 302 operates and draws coupling agent from water tank 301. After being output through the outlet of water pump 302, the coupling agent passes through defoaming device 303 to remove air bubbles generated in the coupling agent due to the pressurization disturbance of water pump 302. Subsequently, fluid valve 304 opens, and the coupling agent is sprayed out through nozzle. Due to the semi-enclosed structure of nozzle 302 itself, the water flow, after contacting the back of the thin-walled part, will form a back pressure pointing towards nozzle 201 to a certain extent, which is positively correlated with the thickness measurement water pressure.

[0165] During the measurement process, to maintain consistency between the preceding and following measurements, it is necessary to keep the thickness measurement water pressure constant. To address this, in this embodiment, a water pressure sensor 305 is introduced between the fluid valve 304 and the defoaming device 303 to collect the drainage back pressure and output the real-time water pressure value. For the nozzle 201, a standard water pressure value was pre-calibrated experimentally, and by controlling the real-time water pressure value to match the standard value, a better thickness measurement effect is achieved.

[0166] The control process of real-time water pressure value can be achieved by processing the difference between real-time water pressure value and standard water pressure value based on PID algorithm and controlling the speed of water pump 302. Alternatively, it can be achieved by bypassing pressure relief.

[0167] Specifically, a three-way connector is installed upstream of the fluid valve 304, which connects to the water inlet of the water tank 301 via an electric ball valve 306, forming a return channel from the water pump 302 to the electric ball valve 306 and then to the water tank 301. The opening angle of the electric ball valve 306 depends on the difference between the real-time water pressure value and the standard water pressure value. Specifically, when the water pressure difference is positive, it indicates that the real-time water pressure value exceeds the standard water pressure value, and the opening angle of the electric ball valve 306 increases, thus reducing the real-time water pressure value; when the water pressure difference is negative, it indicates that the real-time water pressure value is lower than the standard water pressure value, and the opening angle of the electric ball valve 306 decreases, thus reducing the real-time water pressure value.

[0168] In one embodiment, as shown in Figure 12, the thin-walled part machining contour detection process includes:

[0169] The processed thin-walled part is scanned to obtain the processed point cloud data, and the processed scanned surface is generated according to the processed point cloud data.

[0170] The feature regions in the designed surface are identified to obtain the boundaries of the feature regions;

[0171] The boundary of the feature region is projected onto the processed scanned surface, and then geodesic verification is performed on the first feature point in the feature region boundary and the second feature point on the processed scanned surface.

[0172] Specifically, to ensure the processed thin-walled part matches the designed surface, the processed contour of the thin-walled part is inspected after the processing and thickness measurement of the thin-walled part are completed. Specifically, for the designed surface, feature regions and feature points within these regions are pre-marked for comparison. After processing, the same line laser is used to scan the processed thin-walled part to obtain point cloud data, and the scanned surface is reconstructed. Correspondingly, a feature boundary recognition algorithm is used to extract the pre-marked feature region boundaries for the designed surface. Since the designed surface and the thin-walled part have been aligned beforehand, the feature region boundaries can now be projected onto the scanned surface. Then, geodesic information is calculated for the feature points corresponding to the feature regions on the scanned surface. This geodesic information is compared with the geodesic information of the pre-marked feature points on the designed surface to determine whether the processed contour meets expectations.

[0173] A processing system for implementing the above-described processing method.

[0174] As shown in Figure 13, the machining system includes a clamping fixture B020, which is used to clamp thin-walled parts.

[0175] The clamping fixture B020 is equipped with a top support device B021, which is used to move synchronously with the milling cutter during mirror milling to support the thin-walled part.

[0176] To implement the above-described machining method, this embodiment also provides a corresponding machining system. This machining system should include at least a mirror milling system B010, a clamping fixture B020, a surface scanning device B030, a machining process measuring device B040, and a control device B050. The clamping fixture B020 includes a support device B021, which moves synchronously with the milling cutter during mirror milling to support the thin-walled part. The machining process measuring device B040 provides real-time machining process data to the control device B050 during mirror milling to achieve closed-loop control. The control device B050 controls the above modules according to a pre-configured computer program.

[0177] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A mirror milling machining and measurement and control process method, characterized in that, The mirror milling and measurement and control process includes the clamping and transfer process of thin-walled parts, the measurement and point cloud acquisition process of thin-walled parts, the program porting process of thin-walled parts machining path, the post-processing process of thin-walled parts machining path, the machining and thickness measurement and control process of thin-walled parts, and the machining contour detection process of thin-walled parts. The process of porting the machining path for thin-walled parts includes: Based on the actual positioning holes in the point cloud data obtained from scanning the thin-walled part and the theoretical positioning holes on the theoretical triangular mesh surface generated based on the design surface, align the actual triangular mesh surface corresponding to the point cloud data with the theoretical triangular mesh surface. For multiple tool positions in the tool position file, calculate the geodesic information between each tool position and the theoretical positioning hole; Based on the geodesic information, the tool position point is transferred to the actual triangular mesh surface to form a transfer processing path.

2. The mirror milling and measurement control process method according to claim 1, characterized in that, During the clamping and transfer process of the thin-walled part, a clamping fixture is used to clamp the thin-walled part. The clamping fixture includes a fixture frame, which is U-shaped, and multiple movable columns are distributed inside the fixture frame. The tooling frame and the movable column are equipped with grippers, which clamp and fix the thin-walled part. The tooling frame also contains multiple top support devices, which move from the back of the thin-walled component to the front to support it.

3. The mirror milling and measurement control process method according to claim 2, characterized in that, The thin-walled component clamping and transfer process includes: The thin-walled component is hoisted into the tooling frame, and a laser projection is projected onto the tooling frame; The thin-walled component is located within the coverage area of ​​the laser projection; Adjust the top support device and the gripper according to the laser projection and tooling procedure, so as to Adjust the thin-walled part to the predetermined processing state; The thin-walled components are clamped sequentially, and then scanned to obtain the point cloud data.

4. The mirror milling and measurement control process method according to claim 1, characterized in that, During the measurement and point cloud acquisition process of the thin-walled component, the thin-walled component is scanned and the point cloud data is constructed by using a machine tool driven line laser.

5. The mirror milling and measurement control process method according to claim 1, characterized in that, The process of extracting tool positions from the tool position file includes: The theoretical positioning hole center coordinates are extracted from the theoretical triangular mesh surface, and the tool position information of each tool position is extracted from the tool position file. The tool position information includes the tool position coordinates; For each tool position point, the tool position point is projected onto the theoretical mesh surface of the theoretical triangular mesh surface to generate a first projection point and the projection length between the first projection point and the coordinates of the tool position point; Calculate the area coordinates of the first projection point relative to the grid of projection points it belongs to. For each theoretical positioning hole center coordinate, calculate the geodesic length relative to the area coordinates to serve as the geodesic information.

6. The mirror milling and measurement control process method according to claim 1, characterized in that, The path transplantation process that forms the transplantation processing path includes: The actual positioning hole center coordinates of the actual positioning hole are extracted from the point cloud data, and the tool position point is projected onto the actual grid surface corresponding to the point cloud data to obtain a second projection point. The length of the pre-projected geodesic line relative to the actual positioning hole center coordinates of the second projection point is calculated, and then the geodesic line deviation value is obtained by processing the geodesic line information and the pre-projected geodesic line length. The second projection point is iterated according to the geodesic deviation value and the preset geodesic deviation range until the geodesic deviation range is met, and then it is used as the actual transplant point. The transplantation processing path is generated based on the actual transplantation point.

7. The mirror milling and measurement control process method according to claim 1, characterized in that, The post-processing of the thin-walled part machining path includes generating a new transplant tool position file according to the transplant machining path, and performing simulation verification on the transplant tool position file. During the processing and thickness measurement and control of the thin-walled part, the transplanted tool position file is used to process the thin-walled part.

8. The mirror milling and measurement control process method according to claim 2, characterized in that, During the processing and thickness measurement and control of the thin-walled part, the supporting device is also used to support the sunken area of ​​the thin-walled part.

9. The mirror milling and measurement control process method according to claim 1, characterized in that, During the processing and thickness measurement and control of the thin-walled part, an ultrasonic probe is used to measure the thickness of the thin-walled part in real time to obtain the real-time thickness of the thin-walled part. The real-time thickness is used to control the mirror milling process of the thin-walled part.

10. The mirror milling and measurement control process method according to claim 9, characterized in that, The ultrasonic probe has multiple eddy current sensors distributed circumferentially. The eddy current sensors are used to generate eddy currents during the measurement process of the ultrasonic probe to measure the eddy current spacing of the ultrasonic probe relative to the thin-walled component. During the mirror milling process, the distance between the ultrasonic probe and the thin-walled part is also controlled based on the eddy current spacing.

11. The mirror milling and measurement control process method according to claim 10, characterized in that, During the measurement process of the ultrasonic probe, the ultrasonic probe is controlled to point towards the back normal of the thin-walled component by an eddy current normal holding process; The eddy current normal holding process includes: Obtain the distances of multiple eddy current sensors relative to the back surface of the thin-walled component; A machine tool coordinate system is constructed based on the eddy current distribution generated by the eddy current sensor, and the back surface distance is transferred into the machine tool coordinate system respectively; The distribution center of the eddy current coincides with the origin of the machine tool coordinate system; The eddy current normal vector is calculated in the machine tool coordinate system according to the back face distance obtained by transplantation; The orientation of the ultrasonic probe is adjusted based on the eddy current normal vector so that the eddy current normal vector coincides with the back normal vector of the thin-walled component.

12. The mirror milling and measurement control process method according to claim 9, characterized in that, The ultrasonic probe is a water immersion ultrasonic probe. A nozzle is provided on the outside of the coupling part of the ultrasonic probe. The nozzle is used to output water flow that fills the area between the coupling part and the thin-walled component during the measurement process of the ultrasonic probe. The nozzle is equipped with a water pressure sensor in front of it and collects real-time water pressure values. During the mirror milling process, the real-time water pressure value is compared with the water pressure standard value to adjust the water flow pressure and support the thin-walled part through water pressure.

13. The mirror milling and measurement control process method according to claim 1, characterized in that, The thin-walled part machining contour detection process includes: The processed thin-walled part is scanned to obtain the processed point cloud data, and a processed scanned surface is generated according to the processed point cloud data; The feature regions in the designed surface are identified to obtain the boundaries of the feature regions; The boundary of the feature region is projected onto the processed scanned surface, and then geodesic verification is performed on the first feature point in the boundary of the feature region and the second feature point on the processed scanned surface.

14. A processing system, characterized in that, Used to implement the mirror milling and measurement and control process method as described in any one of claims 1-13.

15. The processing system according to claim 14, characterized in that, The processing system includes a clamping fixture for holding thin-walled parts. The clamping fixture is equipped with a top support device, which is used to move synchronously with the milling cutter during mirror milling to support the thin-walled part. An ultrasonic probe is provided on the top of the top support device. The ultrasonic probe is used to measure the thickness from the back of the thin-walled part during the mirror milling process. An eddy current sensor is provided circumferentially on the ultrasonic probe, and the processing system controls the ultrasonic probe to maintain a constant normal and spacing relative to the thin-walled part according to the eddy current sensor. A nozzle is provided on the outer side of the coupling part of the ultrasonic probe. The nozzle is used to output water flow that fills the area between the coupling part and the thin-walled member during the measurement process of the ultrasonic probe. The nozzle is equipped with a water pressure sensor that collects real-time water pressure values. During the mirror milling process, the pressure of the water flow is adjusted by comparing the real-time water pressure value with the standard water pressure value.

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