Multi-spindle hole drilling end effector for aeroengine nacelle acoustic liner hole drilling

Abstract

This invention discloses a multi-spindle end effector for drilling acoustic liner holes in aero-engine nacelles, relating to the field of digital aircraft assembly and manufacturing. It includes an actuator frame, a spindle assembly, a feed assembly, and a pressure foot assembly. The actuator frame includes a front plate and a rear plate. The spindle assembly passes through the front plate and is correspondingly connected to the pressure foot assembly. The feed assembly is mounted on the rear plate and is positioned corresponding to the spindle assembly. The feed assembly controls the extension or retraction of the corresponding spindle assembly and pressure foot assembly. This multi-spindle end effector for drilling acoustic liner holes in aero-engine nacelles can be integrated with industrial robots or CNC machine tools to achieve high-quality and efficient machining of large-scale noise reduction liner holes in aero-engine nacelles, providing technical support for the design and development of multi-spindle end effectors for aero-engine nacelle acoustic liner drilling and the formulation of related standards.

Description

Technical Field

[0001] This invention relates to the field of digital assembly and manufacturing of aircraft, and in particular to a multi-spindle end effector for drilling holes in the acoustic liner of aero-engine nacelles. Background Technology

[0002] Aircraft engine noise is the primary source of aircraft noise, and fan noise is a major component of aircraft engine noise. Fan noise control level is a crucial indicator of the sophistication of modern aircraft engines. To reduce aircraft engine fan noise, an acoustic liner is installed inside the aircraft engine nacelle. Based on the Helmholtz resonance principle, sound energy is dissipated along the noise radiation propagation path through acoustic liner holes and honeycomb cavities. Because the large number, complex arrangement, and precise positioning of the acoustic liner holes all affect the acoustic impedance of the liner, the hole fabrication is a critical step in nacelle acoustic liner manufacturing.

[0003] The current aerospace-grade hole-making methods rely on manual operation, which suffers from poor precision and involves a large amount of repetitive work, making it time-consuming and labor-intensive. Researchers have also developed a robotic automated hole-making system. However, these robotic hole-making systems all use a single-spindle end effector, completing the machining of one hole at a time, which is insufficient to meet the high-efficiency machining requirements for large-scale, small-pitch, and low-noise-reduction lining hole machining.

[0004] In view of this, the inventors of this case conducted in-depth research on the above-mentioned problems, which led to the creation of this case. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-spindle end effector for machining acoustic lining holes in aero-engine nacelles, which can complete the machining of multiple holes in one positioning, so as to achieve high-quality and efficient machining of large-scale noise reduction lining holes in aero-engine nacelles.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-spindle end effector for borehole making of acoustic lining in aero-engine nacelles includes an actuator frame, a spindle assembly, a feed assembly, a solenoid valve assembly, and a pressure foot assembly. The actuator frame includes a front plate and a rear plate arranged opposite each other. The spindle assembly, feed assembly, and solenoid valve assembly are all located inside the actuator frame. The pressure foot assembly is located on the rear plate and outside the actuator frame. The feed assembly is located on the rear plate. One end of the spindle assembly corresponds to the feed assembly, and the other end passes through the front plate and is connected to the pressure foot assembly. The feed assembly is used to control the extension or retraction of the corresponding spindle assembly and pressure foot assembly.

[0007] Preferably, it also includes a hole-making position error measurement system for measuring the angle between the hole-making direction of the equivalent machined hole of the multi-spindle hole-making end effector and the surface normal of the equivalent machined hole on the nacelle acoustic liner. The hole-making position error measurement system includes a laser displacement sensor group installed on the multi-spindle hole-making end effector. The laser displacement sensor group includes four laser displacement sensors for measuring the deviation between the actual tool coordinate system Z-axis and the ideal tool coordinate system Z-axis. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the coordinate system Z-axis is parallel to the hole-making direction.

[0008] Preferably, it also includes a hole-making direction deviation measurement system for measuring the position coordinates of pre-made reference holes on the nacelle acoustic liner and calculating the hole-making position error at each reference hole position coordinate. The hole-making direction deviation measurement system includes a vision unit mounted on the multi-spindle hole-making end effector. The vision unit includes a light source for providing good shooting lighting conditions and an industrial camera and telecentric lens for measuring the actual position coordinates of the reference holes. The direction of the light source is parallel to the direction of the spindle assembly.

[0009] Preferably, it also includes an ultrasonic sensor group for collision detection, the ultrasonic sensor group comprising four ultrasonic sensors, which are respectively mounted at the four corners of the front panel.

[0010] Preferably, the spindle group includes n spindles, the feed group includes n cylinders, and the presser foot group includes n presser feet, where n is an even number greater than 0. Each spindle and cylinder is set in a one-to-one correspondence with the presser foot, and each cylinder independently controls the extension and retraction of the corresponding spindle and presser foot.

[0011] Preferably, the solenoid valve group includes n+1 solenoid valves, each solenoid valve having two interfaces: an air inlet and an air outlet. The n solenoid valves are used to control the extension and retraction of the cylinder, and the other solenoid valve is used for the spindle air cooling switch control.

[0012] Preferably, it also includes a vacuum tube assembly for collecting the chips generated during the sound liner hole making process by vacuum at the presser foot. The vacuum tube assembly includes n vacuum tubes, each of which is installed on the side of the presser foot.

[0013] Preferably, a spring is provided between each presser foot and the front plate to press the presser foot against the surface of the sound liner perforated panel, and the spring is correspondingly sleeved on the outer periphery of the spindle.

[0014] Preferably, n is 6.

[0015] Preferably, it also includes an exhaust duct acoustic liner positioning fixture connected to the actuator frame. The exhaust duct acoustic liner positioning fixture includes a rotary conversion station platform and an acoustic liner support base plate disposed on the rotary conversion station platform, a support frame for supporting the acoustic liner support base plate, and a vacuum suction cup disposed on the acoustic liner support base plate. The acoustic liner support base plate is adapted to the inner shape of the exhaust duct acoustic liner, with an arc-shaped part protruding outward from its middle. The support frame includes a triangular support frame for supporting the periphery of the acoustic liner support base plate and several annular support tubes for supporting the arc-shaped part. Each annular support tube is adapted to the arc-shaped part. The acoustic liner support base plate is provided with several mounting holes that are compatible with the vacuum suction cup. The vacuum suction cup is set in the mounting holes, and the suction cup side of the vacuum suction cup is used to realize multi-point flexible support of the acoustic liner. The other side is used to connect the vacuum suction cup to the acoustic liner support base plate. The axial position of the vacuum suction cup in the mounting hole can be adjusted by the nut. Optimal number of vacuum chucks and optimal layout The calculation is as follows: A greedy algorithm was used to establish a numerical simulation model of the exhaust duct acoustic liner deformation under vacuum suction cup conditions, thereby establishing the correlation between the number and layout of vacuum suction cups and the deformation of the exhaust duct acoustic liner and vacuum suction cups. ; in: Cost of configuring vacuum suction cups; This refers to the number of vacuum suction cups; Vacuum suction cup layout; The relationship between the configuration cost of vacuum suction cups and their quantity and layout; For exhaust duct deformation and its tolerance; For the deformation and tolerance of vacuum chucks; This is the optimal solution obtained based on a greedy algorithm.

[0016] Preferably, the minimum curvature of the curved surface for positioning the exhaust duct acoustic liner is in the horizontal direction. The minimum curvature in the vertical direction is The machining requirement is that the standard deviation of the hole normal should not exceed [a certain value]. Spend; Minimum curvature of the acoustic liner in the horizontal direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum horizontal spacing between spindles is 8 horizontal hole spacings. Assuming the optimal number of principal axes in the horizontal direction is The formula for calculating the maximum normal deviation is as follows: ; in This represents the maximum horizontal normal deviation. Similarly, the minimum curvature of the acoustic liner in the vertical direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum horizontal spacing between spindles is 10 times the spacing of holes drilled in the vertical direction. Assuming the optimal number of principal axes in the horizontal direction is The formula for calculating the maximum normal deviation is as follows: ; in This represents the maximum vertical normal deviation. Considering the normal deviations of the multi-spindle end effector in both the horizontal and vertical directions, the total maximum normal deviation for hole drilling is as follows: ; Analysis revealed the maximum normal deviation of the multi-spindle end effector during hole drilling. Less than the standard deviation of hole normal This ensures that all other spindles meet the requirements for machining with normal deviation in the drilling direction; simultaneously, to minimize the space occupied by the multi-spindle end effector, the number of spindles in both the horizontal and vertical directions is reduced. It should be as close as possible: ; in: The optimal solution that satisfies the maximum hole drilling normal deviation; The number of horizontal spindles of the end effector; The number of vertical spindles of the end effector; This is the difference between the number of horizontal and vertical spindles of the end effector; The optimal number of spindles in the horizontal direction for the end effector; The optimal number of spindles in the horizontal direction for the end effector.

[0017] By adopting the aforementioned design scheme, the beneficial effects of the present invention are as follows: The multi-spindle hole-making end effector of the present invention for making holes for acoustic liners of aero-engine nacelles can be integrated with industrial robots or CNC machine tools to achieve high-quality and efficient processing of large-scale noise reduction lining holes for aero-engine nacelles, providing technical support for the design and development of multi-spindle hole-making end effectors for acoustic liners of aero-engine nacelles and the formulation of related standards. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the multi-spindle hole-making control system for robots in this invention; Figure 2 This is an isometric view of the multi-spindle hole-making system for robots in this invention; Figure 3 This is a front view of the robot multi-spindle hole-making system of the present invention; Figure 4 This is a side view of the robot multi-spindle hole-making system of the present invention; Figure 5 This is a top view of the robot multi-spindle hole-making system of the present invention; Figure 6 This is an isometric view of the multi-spindle bore end effector of the present invention; Figure 7 This is a front view of the multi-spindle bore end effector of the present invention; Figure 8 This is a top view of the multi-spindle bore end effector of the present invention; Figure 9 This is a side view of the multi-spindle bore end effector of the present invention; Figure 10 This is an isometric view (front view) of the exhaust duct acoustic liner positioning fixture in this invention. Figure 11 This is an isometric view (rear view) of the exhaust duct acoustic liner positioning fixture in this invention. Figure 12 This is a front view of the exhaust duct acoustic liner positioning fixture in this invention; Figure 13 This is a side view of the exhaust duct acoustic liner positioning fixture in this invention; Figure 14 This is a top view of the exhaust duct acoustic liner positioning fixture in this invention; In the diagram: 1. Industrial robot; 2. Robotic arm; 3. Multi-spindle end effector; 3. Actuator frame; 31. First side plate; 311. Second side plate; 312. Spindle assembly; 32. Feed assembly; 33. Solenoid valve assembly; 34. Valve island; 341. Presser foot assembly; 35. Spring; 351. Ultrasonic sensor assembly; 36. Laser displacement sensor assembly; 37. Vision unit; 38. Vacuum tube assembly; 39. Exhaust duct acoustic liner positioning fixture; 4. Rotary conversion station platform; 41. Bottom mounting base; 411. Transmission mechanism; 412. Top support base; 413. Support frame; 42. Triangular support frame; 421. Annular support tube; 422. Acoustic liner support base plate; 43. Mounting hole; 431. Vacuum suction cup; 44. Detailed Implementation

[0019] 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.

[0020] Reference Figures 1 to 14 : This embodiment proposes a control system for drilling holes in the acoustic liner of an aero-engine nacelle, including a robot control system, a PLC control system, a host computer, a multi-spindle drilling system, a drilling direction deviation measurement system, and a drilling position error measurement system. The multi-spindle drilling system includes an industrial robot 1, a robotic arm 2 movably connected to the industrial robot 1, and a multi-spindle drilling end effector 3 located at the end of the robotic arm 2.

[0021] The robot control system is used for the motion and logic control of industrial robot 1 and for real-time feedback of its pose and joint angles.

[0022] The PLC control system selects a suitable communication method, such as Profinet communication, to establish communication between the PLC control system and the robot control system, thereby realizing motion and logic control and status feedback for the industrial robot 1, and simultaneously realizing motion and logic control and status feedback for the multi-spindle end effector 3.

[0023] The host computer serves as the human-machine interface. By installing the robot control system on the host computer, the G-code for the core hole-making process can be imported and executed. Communication between the host computer and the PLC control system is achieved by calling communication libraries such as HSL Communication, enabling manual control of the multi-spindle hole-making end effector 3, and displaying and storing the motion status data of the industrial robot 1 and the multi-spindle hole-making end effector 3.

[0024] The hole-making position error measurement system is a laser displacement sensor group 37 (which will be described in detail below) installed on the multi-spindle hole-making end effector 3. It measures the angle between the hole-making direction of the equivalent machined hole of the multi-spindle hole-making end effector 3 and the normal of the curved surface at the equivalent machined hole on the nacelle acoustic liner.

[0025] The hole-making position error measurement system is a vision unit 38 (which will be described in detail below) installed on the multi-spindle hole-making end actuator 3. It measures the position coordinates of the pre-made reference holes on the nacelle acoustic liner, and then obtains the hole-making position error at each reference hole position in the nacelle acoustic liner product coordinate system.

[0026] Preferably, the multi-spindle bore end effector 3 is connected to the robotic arm 2 via a flange. The multi-spindle bore end effector 3 includes an actuator frame 31, a spindle assembly 32, a feed assembly 33, a solenoid valve assembly 34, a pressure foot assembly 35, an ultrasonic sensor assembly 36, a laser displacement sensor assembly 37, and a vision unit 38. The actuator frame 31 is the mounting base for each component in the multi-spindle bore end effector 3.

[0027] The actuator frame 31 has a cubic frame structure. Two opposite side plates of the actuator frame 31 are defined as the first side plate 311 and the second side plate 312. The pressure foot assembly 35, the ultrasonic sensor assembly 36, the laser displacement sensor assembly 37 and the vision unit 38 are all mounted on the first side plate 311. The feed assembly 33 and the solenoid valve assembly 34 are all mounted on the second side plate 312. The spindle assembly 32 is mounted inside the actuator frame 31, and one end passes through the first side plate 311 and is correspondingly connected to the pressure foot assembly 35. The feed assembly 33 is used to control the extension or retraction of the corresponding spindle assembly 32 and pressure foot assembly 35.

[0028] Furthermore, the spindle assembly 32 consists of n spindles arranged in an array, the feed assembly 33 consists of n cylinders arranged in an array, and the pressure foot assembly 35 consists of n pressure feet arranged in an array, where n is an even number greater than 0. The number of spindle assemblies 32, feed assemblies 33, and pressure foot assemblies 35 is the same, and each spindle and cylinder is correspondingly arranged with a pressure foot. The cylinders are used to control the extension and retraction of the corresponding spindle and pressure foot. Preferably, a spring 351 is provided between each pressure foot and the first side plate 311 to press the pressure foot against the surface of the perforated acoustic liner panel. Each spring 351 is respectively sleeved on the outer periphery of the spindle. Driven by each cylinder, the pressure foot extends and presses against the surface of the perforated acoustic liner panel under the pressure of the spring, based on the friction between the end face of the pressure foot and the surface of the perforated panel. In this embodiment, the acoustic liner part and the spindle hole-making end actuator 3 are coupled into a whole to improve the rigidity and stability of the hole-making system and reduce vibration during the hole-making process.

[0029] In this embodiment, n=6.

[0030] Furthermore, the multi-spindle hole-making end effector 3 also includes a vacuum tube group 39, which consists of n vacuum tubes arranged in an array. Each vacuum tube is installed on the side of the pressure foot. Based on the principle of vacuum chip removal, the chips generated during the sound liner hole-making process are collected from the pressure foot into a dust collector (not shown in the figure).

[0031] Furthermore, the solenoid valve assembly 34 consists of an array of n+1 solenoid valves, each including an inlet and an outlet. Six of these solenoid valves control the extension and retraction of the cylinders in the cylinder array, while the remaining valve controls the spindle air cooling switch. Preferably, the second side plate 312 also has a valve island 341 for mounting the solenoid valve assembly 34. The valve island 341 can independently control the solenoid valves in the solenoid valve assembly 34 based on the same air source.

[0032] The ultrasonic sensor group 36 includes four ultrasonic sensors for collision detection, which are evenly distributed and installed at the four corners of the first side plate 311.

[0033] The laser displacement sensor group 37 includes four laser displacement sensors for measuring the deviation between the actual tool coordinate system Z-axis (the axis parallel to the drilling direction) and the ideal tool coordinate system Z-axis. The four laser displacement sensors are evenly distributed at the four corners of the first side plate 311 to provide a basis for end effector attitude correction.

[0034] The vision unit 38 includes a light source to provide good lighting conditions for shooting, and an industrial camera and telecentric lens for measuring the actual position coordinates of the reference holes. The optical axis is parallel to the directions of each spindle on the spindle assembly 32. The light source provides good lighting conditions for shooting, and the industrial camera and telecentric lens measure the actual position coordinates of the reference holes. A hole-making direction deviation measurement system controls the object distance and optical axis direction during industrial camera measurement. After calculating the deviation between the actual positions of multiple reference holes and their corresponding nominal positions, the hole-making positioning error can be calculated based on a certain interpolation compensation strategy, providing a basis for end effector position correction.

[0035] This embodiment also includes an exhaust duct acoustic liner positioning fixture 4 connected to the multi-spindle bore end effector 3. The exhaust duct acoustic liner positioning fixture 4 includes a rotary conversion station platform 41, a support frame 42, an acoustic liner support base plate 43, and a vacuum suction cup 44.

[0036] The rotary conversion station platform 41 includes a bottom mounting base 411, a transmission mechanism 412 consisting of an external gear ring and gears, and a top support base 413. The bottom mounting base 411 is used to install the rotary conversion station platform 41 onto the factory floor, the top support base 413 is used to mount the support frame 42, and the transmission mechanism 412 consisting of the external gear ring and gears is used to achieve relative rotation of the top support base 413 relative to the bottom mounting base 411.

[0037] The support frame 42 consists of a triangular support frame 421 and multiple annular support tubes 422. The triangular support frame 421 is the main support structure, and the annular support tubes 422 are auxiliary back support parts of the acoustic liner support base plate 43. The two together provide support for the entire acoustic liner support base plate 43.

[0038] The acoustic liner support base plate 43 is designed to mimic the inner shape of the acoustic liner in the exhaust duct. Based on a mechanical connection, the acoustic liner support base plate 43 is installed on the support frame 42. Multiple approximately evenly distributed vacuum suction cup 44 mounting holes 431 are designed on the acoustic liner support base plate 43. The vacuum suction cup 44 is installed in the mounting holes 431 of the acoustic liner support base plate 43, using a single-sided fixing method. The suction cup side of the vacuum suction cup 44 is used to achieve multi-point flexible support for the acoustic liner, and the other side is used to connect the vacuum suction cup 44 to the acoustic liner support base plate 43. The axial position of the vacuum suction cup 44 in the mounting hole 431 can be adjusted by a nut.

[0039] Furthermore, the number of vacuum suction cups 44 directly affects the cost and system complexity. The following method is used for optimization: with the goal of minimizing the configuration cost of vacuum suction cups 44, the number and layout of vacuum suction cups 44 are used as design variables, and the exhaust duct acoustic liner and the deformation of vacuum suction cups 44 are used as constraints. The following formula is used to establish an optimization model for the number and layout of vacuum suction cups 44. SA1. A greedy algorithm is used to solve for the optimal number and layout of vacuum suction cups 44. Specifically, a numerical simulation model of the exhaust duct acoustic liner deformation under vacuum suction cup 44 conditions is established to determine the correlation between the number and layout of vacuum suction cups 44 and the exhaust duct acoustic liner and vacuum suction cup 44 deformation. (A1); in: Cost of configuring vacuum suction cup 44; The number of vacuum suction cups is 44; The vacuum suction cup has a 44-fold layout; The relationship between the configuration cost of vacuum suction cup 44 and its quantity and layout; For exhaust duct deformation and its tolerance; Deformation and tolerance of vacuum chuck 44; The optimal solution obtained based on a greedy algorithm includes the optimal number of 44 vacuum suction cups. and optimal layout ; SA2, the steps for positioning and changing the exhaust duct acoustic liner using exhaust duct acoustic liner positioning fixture 4 are as follows: SA21, based on the area to be processed of the exhaust duct acoustic liner, adjusts the relative position of the exhaust duct acoustic liner and the processing robot through the rotary conversion station platform 41 of the exhaust duct acoustic liner positioning fixture, so as to expand the processing space of the processing robot. SA22, based on the optimal number of vacuum suction cups 44 and optimal layout The design includes vacuum suction cup 44 mounting holes 431 on the sound liner support base plate 43; Install the vacuum suction cup 44 in the mounting hole 431, and fine-tune the position of the vacuum suction cup 44 in the axial direction of the mounting hole 431 so that the exhaust duct acoustic liner is tightly attached to the acoustic liner support base plate 43 under vacuum adsorption. The pneumatic vacuum suction cup 44 achieves multi-point adsorption and fixation of the exhaust duct acoustic liner through negative pressure, so as to prepare for the processing robot to process the acoustic liner hole.

[0040] The host computer controls the PLC control system, which sends instructions to the industrial robot 1, driving the multi-spindle hole-making end effector 3 to its initial pre-specified position. The measurement coordinate system is moved to coincide with the nominal coordinate system of the reference hole, and the acquired pose information is transmitted to the PLC control system. The PLC control system compares the actual position coordinates of the reference hole with its nominal coordinates, reads data from each laser rangefinder sensor via the I / O module, calculates the pose deviation matrix of the tool coordinate system, and determines the attitude adjustment command to send to the multi-spindle hole-making end effector 3. The multi-spindle hole-making end effector 3 adjusts its attitude according to the command. After the multi-spindle drilling end effector 3 moves to the target machining position, the PLC control system drives the industrial robot 1 to move, eliminating the drilling direction deviation at the target machining position. After the multi-spindle drilling end effector 3 reaches the target machining position, the position of the industrial robot 1 is locked. The PLC control system sends a drilling command to the multi-spindle drilling end effector 3, and the multi-spindle drilling end effector 3 performs drilling after receiving the drilling command. After completing the drilling operation, feedback is sent to the PLC control system, which sends a command to control the industrial robot 1 to drive the multi-spindle drilling end effector 3 back to the pre-specified position, completing one operation process.

[0041] The host computer generates hole processing technology information based on the hole position design information and sends it to the PLC control system (lower computer); it receives the pose information sent by the industrial camera through the communication layer, determines the hole-making direction deviation of the industrial robot 1 at the target processing position, and sends the direction deviation to the lower motion control layer.

[0042] The minimum curvature of the curved surface for exhaust duct acoustic liner positioning is in the horizontal direction. The minimum curvature in the vertical direction is The machining requirement is that the standard deviation of the hole normal should not exceed [a certain value]. Spend; Since the surface of the acoustic liner is curved, and the spindles of the multi-spindle end effector are arranged on the same horizontal plane, the normal deviation of the hole is inevitably generated during the multi-spindle hole making process. The more spindles in the same direction, the higher the hole making efficiency. However, due to the limitations of the transmission structure, the larger the hole making span of the multi-spindle end effector, the greater the normal deviation of the hole making. Therefore, there is an optimal value for the number of spindles. Minimum curvature of the acoustic liner in the horizontal direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum horizontal spacing between spindles is 8 horizontal hole spacings. Assuming the optimal number of principal axes in the horizontal direction is The formula for calculating the maximum normal deviation is as follows: ; in This represents the maximum horizontal normal deviation. Similarly, the minimum curvature of the acoustic liner in the vertical direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum horizontal spacing between spindles is 10 times the spacing of holes drilled in the vertical direction. Assuming the optimal number of principal axes in the horizontal direction is The formula for calculating the maximum normal deviation is as follows: ; in This represents the maximum vertical normal deviation. Considering the normal deviations of the multi-spindle end effector in both the horizontal and vertical directions, the total maximum normal deviation for hole drilling is as follows: ; Analysis revealed the maximum normal deviation of the multi-spindle end effector during hole drilling. Less than the standard deviation of hole normal This ensures that all other spindles meet the requirements for machining with normal deviation in the drilling direction; simultaneously, to minimize the space occupied by the multi-spindle end effector, the number of spindles in both the horizontal and vertical directions is reduced. It should be as close as possible: ; in: The optimal solution that satisfies the maximum hole drilling normal deviation; The number of horizontal spindles of the end effector; The number of vertical spindles of the end effector; This is the difference between the number of horizontal and vertical spindles of the end effector; The optimal number of spindles in the horizontal direction for the end effector; The optimal number of spindles in the horizontal direction for the end effector.

[0043] This embodiment also proposes a method for controlling the acoustic liner holes of an aero-engine nacelle, which is carried out according to the following steps: S1, the host computer calls the communication library to control the PLC control system; The PLC control system drives the industrial robot to move and moves the camera measurement coordinate system of the multi-spindle hole-making end effector to coincide with the pose of the nominal coordinate system of the reference hole. The host computer controls the industrial camera to capture images of the reference hole and calculates the actual position coordinates of the reference hole. Based on the actual position coordinates of the reference holes and the origin of the nominal coordinate system of the reference holes, the position error of each reference hole is calculated, and then the hole-making position error of the position to be processed within the area surrounded by each reference hole is calculated by interpolation compensation. The hole-making position error is corrected according to the following steps: S11 uses a vision unit integrated on the end effector of the robot's multi-spindle hole-making system to capture images of the reference hole; Here, the camera's optical axis is defined as parallel to the axis of the principal array, and the object distance during visual shooting is defined as... and the perpendicularity of the optical axis to the acoustic liner surface The focal distance and the pose of the visual unit when the optical axis is perpendicular to the acoustic liner surface are obtained. (1); in: Visual unit coordinate system Relative nacelle acoustic liner product coordinate system The position; For the calibrated robot base coordinate system Relative to the product coordinate system The position; To obtain the robot flange coordinate system based on the robot kinematic model Relative to the robot's base coordinate system The position; For the calibrated robot tool coordinate system Relative to the flange coordinate system The position; For the already labeled hand-eye relationship, i.e., the visual unit coordinate system Relative to the tool coordinate system The position; Indicates the focal distance; This indicates that the optical axis is perpendicular to the acoustic liner surface, i.e., the angle is 90°. S12, following S11, uses a robust, accurate, and efficient benchmark hole feature localization algorithm that integrates visual saliency and mean shift to obtain the benchmark hole features in the benchmark hole image. The specific steps are as follows: S121, the obtained original reference hole image Perform Gaussian filtering or median filtering to obtain the corresponding smoothed image. For smoothed images Perform image contrast stretching to obtain an enhanced image. The saliency of the original reference hole image is calculated according to formula (2). ; (2); in: This represents the calculation of the average pixel value of an image. This indicates that the maximum pixel value of the image is retrieved; This indicates that the minimum pixel value of the image is retrieved; S122, Select the saliency map of the reference hole image through region filtering. Obtain the centroid coordinates of the largest salient region in the region. The coordinates of each pixel position and the centroid coordinates of the saliency map are calculated according to formula (3). Distance map ; The weight map is calculated according to formula (4). ; According to the weighting diagram in formula (5) With saliency map Multiplying corresponding elements together removes fragmented salient regions from the salient map, resulting in an updated salient map. ; (3); (4); (5); S123, Based on an automatic threshold segmentation method or by selecting a suitable fixed threshold through repeatability testing, update the saliency map after S122. Threshold segmentation is performed to segment the reference hole feature region from the saliency map; Using edge detection operators or contour extraction algorithms, the baseline hole contour is extracted from the threshold segmentation map of the saliency map. The contour point set is approximately divided into three continuous subsets. Contour points are randomly selected from the three subsets multiple times for circle fitting. The coordinates of the center of all fitted circles are stored in an array. From all the candidate centers, one is randomly selected as the initial centroid. Using this as the center, and based on a preset scanning radius, the mean-drift algorithm is used to iteratively find the true centroid of the set of center centers, which serves as the coordinate system for the reference hole center. ; S13, Set the image coordinate system at the center of the image, with its coordinate axes aligned with the default image coordinate axes. Based on the coordinates of the reference hole center obtained in S12... Combined with the calibrated intra-visual unit parameters and the known image width and height ; The XY plane and its coordinate axes of the visual unit coordinate system are defined to coincide with the coordinate axes of the image coordinate plane and its coordinate system. The physical coordinates of the reference hole in the visual unit coordinate system are obtained according to formula (6). ; (6); Based on formula (7) and S1, the following is obtained: The homogeneous transformation matrix of the reference hole in the product coordinate system is obtained. , By rotation matrix Translation vector composition; Translation vector The transpose of the coordinates of the reference hole in the product coordinate system obtained by the vision unit measurement is given. ; (7); Combining the nominal coordinates of the reference hole in the product coordinate system The hole positioning error at the reference hole is obtained. ; (8); S14. For all reference holes, repeat steps S11 to S13 to measure the hole positioning error at all reference holes using a vision system. S15, through surface interpolation, obtain the hole positioning error at other hole locations within the influence area of ​​the reference hole, and compensate for these errors; S21, the host computer calls the communication library to control the PLC control system; The PLC control system drives the industrial robot to move and moves the tool coordinate system of the multi-spindle hole-making end effector to the target machining position. The PLC control system reads data from each laser rangefinder through the I / O module, calculates the hole-making direction deviation using the algorithm, and then calculates the pose deviation matrix of the tool coordinate system. S3, based on the hole-making position error of the position to be processed obtained by S1, update and save the hole-making position coordinates in the current acoustic liner hole. The PLC control system drives the industrial robot to move and move the tool coordinate system of the multi-spindle hole-making end effector to the target processing pose. The tool coordinate system pose deviation matrix is ​​obtained according to S2. Based on this deviation matrix, the PLC control system drives the industrial robot to move and eliminate the hole-making direction deviation at the target machining position. After the multi-spindle hole-making end effector reaches the target machining posture, the industrial robot posture is locked, and the PLC control system drives the rotation of each independent control spindle of the multi-spindle hole-making end effector as well as the extension of the presser foot and spindle to complete the machining of the acoustic liner hole. S4. After the hole making is completed, the PLC control system controls the spindle and pressure foot to retract and moves the industrial robot to the next target processing position to process the next hole. Until all acoustic liner holes in the hole making area are processed, the PLC control system drives the industrial robot to a safe position and shuts down each hole making spindle.

[0044] By adopting the aforementioned design scheme, the beneficial effects of the present invention are as follows: the control system and control method for drilling holes in the acoustic liner of the aero-engine nacelle of the present invention can realize flexible, high-quality and efficient processing of large-scale noise reduction liner holes in the nacelle acoustic liner, realize accurate measurement of hole positioning error, thereby shortening the manufacturing cycle of the aero-engine nacelle acoustic liner parts, and providing a theoretical basis and technical support for the specification of the drilling process specifications for the aero-engine nacelle acoustic liner.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-spindle end effector for borehole making in the acoustic liner of an aircraft engine nacelle, characterized in that: It includes an actuator frame, a spindle assembly, a feed assembly, a solenoid valve assembly, and a pressure foot assembly. The actuator frame includes a front plate and a rear plate arranged opposite each other. The spindle assembly, feed assembly, and solenoid valve assembly are all located inside the actuator frame. The pressure foot assembly is located on the rear plate and outside the actuator frame. The feed assembly is located on the rear plate. One end of the spindle assembly corresponds to the feed assembly, and the other end passes through the front plate and is connected to the pressure foot assembly. The feed assembly is used to control the extension or retraction of the corresponding spindle assembly and pressure foot assembly. It also includes a hole-making position error measurement system for measuring the angle between the hole-making direction of the equivalent machined hole of the multi-spindle hole-making end effector and the surface normal of the equivalent machined hole on the nacelle acoustic liner. The hole-making position error measurement system includes a laser displacement sensor group installed on the multi-spindle hole-making end effector. The laser displacement sensor group includes four laser displacement sensors for measuring the deviation between the actual tool coordinate system Z-axis and the ideal tool coordinate system Z-axis. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the coordinate system Z-axis is parallel to the hole-making direction. It also includes a hole-making direction deviation measurement system for measuring the position coordinates of pre-made reference holes on the nacelle acoustic liner and calculating the hole-making position error at each reference hole position coordinate. The hole-making direction deviation measurement system includes a vision unit mounted on the multi-spindle hole-making end effector. The vision unit includes a light source for providing good shooting lighting conditions and an industrial camera and telecentric lens for measuring the actual position coordinates of the reference holes. The direction of the light source is parallel to the direction of the spindle assembly. It also includes an exhaust duct acoustic liner positioning fixture, which includes a rotary conversion station platform and an acoustic liner support base plate set on the rotary conversion station platform, a support frame for supporting the acoustic liner support base plate, and a vacuum suction cup set on the acoustic liner support base plate. The acoustic liner support base plate is adapted to the inner shape of the exhaust duct acoustic liner, with an arc-shaped part protruding outward from its middle. The support frame includes a triangular support frame for supporting the periphery of the acoustic liner support base plate and several annular support tubes for supporting the arc-shaped part. Each annular support tube is adapted to the arc-shaped part. The acoustic liner support base plate is provided with several mounting holes that are compatible with the vacuum suction cup. The vacuum suction cup is set in the mounting holes, and the suction cup side of the vacuum suction cup is used to realize multi-point flexible support of the acoustic liner. The other side is used to connect the vacuum suction cup to the acoustic liner support base plate, and the axial position of the vacuum suction cup in the mounting hole can be adjusted by the nut. Optimal number of vacuum chucks and optimal layout The calculation is as follows: A greedy algorithm was used to establish a numerical simulation model of the exhaust duct acoustic liner deformation under vacuum suction cup conditions, thereby establishing the correlation between the number and layout of vacuum suction cups and the deformation of the exhaust duct acoustic liner and vacuum suction cups. ； in: Cost of configuring vacuum suction cups; This refers to the number of vacuum suction cups; Vacuum suction cup layout; The relationship between the configuration cost of vacuum suction cups and their quantity and layout; For exhaust duct deformation and its tolerance; For the deformation and tolerance of vacuum chucks; This is the optimal solution obtained using a greedy algorithm. The minimum curvature of the curved surface for exhaust duct acoustic liner positioning is in the horizontal direction. The minimum curvature in the vertical direction is The machining requirement is that the standard deviation of the hole normal should not exceed [a certain value]. Spend; Minimum curvature of the acoustic liner in the horizontal direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum horizontal spacing between spindles is 8 horizontal hole spacings. Assuming the number of horizontal principal axes is The formula for calculating the maximum normal deviation is as follows: ； in This represents the maximum horizontal normal deviation. Similarly, the minimum curvature of the acoustic liner in the vertical direction It is known that, due to limitations in the spindle drive structure and ease of machining, the minimum vertical spacing between spindles is 10 vertical hole spacings. Assuming the number of vertical principal axes is The formula for calculating the maximum normal deviation is as follows: ； in This represents the maximum vertical normal deviation. Considering the normal deviations of the multi-spindle end effector in both the horizontal and vertical directions, the total maximum normal deviation for hole drilling is as follows: ； Analysis revealed the maximum normal deviation of the multi-spindle end effector during hole drilling. Less than the standard deviation of hole normal This ensures that all other spindles meet the requirements for machining with normal deviation in the drilling direction; simultaneously, to minimize the space occupied by the multi-spindle end effector, the number of spindles in both the horizontal and vertical directions is reduced. It should be as close as possible: ； in: The optimal solution that satisfies the maximum hole drilling normal deviation; The number of horizontal spindles of the end effector; The number of vertical spindles of the end effector; This is the difference between the number of horizontal and vertical spindles of the end effector; The optimal number of spindles in the horizontal direction for the end effector; The optimal number of spindles in the vertical direction for the end effector.

2. The multi-spindle end effector for creating acoustic liner holes in an aero-engine nacelle according to claim 1, characterized in that: It also includes an ultrasonic sensor array for collision detection, comprising four ultrasonic sensors mounted at the four corners of the front panel.

3. The multi-spindle end effector for creating acoustic liner holes in an aero-engine nacelle according to claim 1, characterized in that: The spindle assembly includes n spindles, the feed assembly includes n cylinders, and the presser foot assembly includes n presser feet, where n is an even number greater than 0. Each cylinder independently controls the extension and retraction of its corresponding spindle and presser foot. The solenoid valve assembly includes n+1 solenoid valves, each with one inlet and one outlet. The n solenoid valves are used to control the extension and retraction of the cylinders, and the other solenoid valve is used for controlling the spindle air cooling switch.

4. The multi-spindle end effector for creating acoustic liner holes in an aircraft engine nacelle according to claim 3, characterized in that: It also includes a vacuum tube assembly for collecting the chips generated during the sound liner hole making process by vacuum at the presser foot. The vacuum tube assembly includes n vacuum tubes, each of which is installed on the side of the presser foot.

5. The multi-spindle end effector for creating acoustic liner holes in an aero-engine nacelle according to claim 3, characterized in that: A spring is provided between each presser foot and the front plate to press the presser foot against the surface of the sound liner perforated panel. The spring is correspondingly sleeved on the outer periphery of the spindle.

6. The multi-spindle end effector for borehole making of acoustic liner in aircraft engine nacelles according to any one of claims 3-4, characterized in that: n is 6.

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