Exhaust Duct Acoustic Liner Positioning Tooling for Drilling Apertures in Aeroengine Nacelle Acoustic Liners

Abstract

The present invention discloses a positioning tooling for exhaust duct acoustic liner for hole making of an aeroengine nacelle, which relates to the field of aeroengine manufacturing. The positioning tooling includes a rotary transfer station platform, an acoustic liner support bottom plate, a support frame and vacuum suckers. The acoustic liner support bottom plate is adapted to the inner shape of the exhaust duct acoustic liner, and a middle part thereof protrudes outwards to form an arc part. The support frame includes a triangular support frame and a plurality of annular support pipes for supporting the arc part, and each annular support pipe is adapted to the arc part. The present invention can realize flexible and efficient positioning of the exhaust duct acoustic liner of the aeroengine nacelle, provide conditions for automatic and precise hole making of the exhaust duct acoustic liner, and can also provide reference for the design of positioning tooling for other acoustic liner parts, and provide technical support for the formulation of relevant design and development specifications or standards.

Description

Technical Field

[0001] The present invention relates to the field of aero-engine manufacturing, and more particularly to a positioning tool for an exhaust duct acoustic liner for making holes in an aero-engine nacelle acoustic liner. Background Art

[0002] Aero-engine noise is the main source of aircraft noise. Fan noise is the main component of aero-engine noise, and the fan noise control level is an important indicator to measure the advancement of modern aero-engines. In order to reduce the fan noise of an aero-engine, an acoustic liner is laid in the aero-engine nacelle. Through the acoustic liner holes and honeycomb cavities, based on the Helmholtz resonance principle, the sound energy is dissipated on the noise radiation propagation path. Since the number of acoustic liner holes is extremely large, the arrangement is complex, and the position accuracy will affect the acoustic impedance of the acoustic liner. Therefore, making holes in the acoustic liner is an important link in the manufacture of the nacelle acoustic liner.

[0003] Since the perforated panel of the acoustic liner is a curved surface part, the number of acoustic liner holes is large, and the accuracy of the acoustic liner holes directly affects the noise reduction effect, it is necessary to adopt an automated hole-making solution with higher hole-making quality and effect. The automated hole-making solution usually includes two core units: a hole-making system and a positioning tool for the product to be processed. The former is used for hole-making processing of the product, and the latter is used to provide positioning for the product during the processing. The two complement each other. In addition, in order to meet the hole-making requirements beyond the working space of the robot body based on a single industrial robot, it is necessary to set a motion axis for the positioning tool to ensure the accessibility of the robot to the product to be processed. Considering that the nacelle acoustic liner is usually a large-curvature curved surface part, and the cutting force for micro-hole machining is relatively small, it is difficult to clamp and position the workpiece, and the degree of automation and intelligence is low, which obviously cannot meet the requirements for making holes in large-scale noise-reducing acoustic liners.

[0004] In view of this, the inventor of this case has conducted in-depth research on the above problems, and thus this case has been created. Summary of the Invention

[0005] The purpose of the present invention is to provide a positioning tool for an exhaust duct acoustic liner for making holes in an aero-engine nacelle acoustic liner, which can achieve flexible and efficient positioning of the exhaust duct acoustic liner of the aero-engine nacelle, and provide conditions for automated and precise hole-making of the exhaust duct acoustic liner.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solution:

[0007] An exhaust duct acoustic lining positioning tooling for hole making of an aeroengine nacelle acoustic lining, comprising a rotary transfer station platform, an acoustic lining support bottom plate arranged on the rotary transfer station platform, a support frame for supporting the acoustic lining support bottom plate, and a vacuum chuck arranged on the acoustic lining support bottom plate. The acoustic lining support bottom plate is adapted to the inner shape of the exhaust duct acoustic lining, and a curved portion protrudes outward from the middle thereof. The support frame includes a triangular support frame for supporting the periphery of the acoustic lining support bottom plate and a plurality of annular support pipes for supporting the curved portion, and each annular support pipe is adapted to the curved portion.

[0008] Preferably, the rotary transfer station platform includes a bottom mounting seat, a top support seat, and a transmission mechanism for driving the top support seat to rotate relative to the bottom mounting seat. The transmission mechanism is arranged between the bottom mounting seat and the top support seat, and the support frame is arranged on the top support seat. The transmission mechanism includes an external gear ring and a gear.

[0009] Preferably, a plurality of mounting holes adapted to the vacuum chuck are arranged on the acoustic lining support bottom plate. The vacuum chuck is arranged in the mounting holes, and the suction cup side of the vacuum chuck is used to realize the multi-point flexible support of the acoustic lining, and the other side is used to connect the vacuum chuck to the acoustic lining support bottom plate, and the axial position of the vacuum chuck in the mounting hole can be adjusted by a nut.

[0010] Preferably, the optimal number and optimal layout of the vacuum chuck are calculated as follows:

[0011] Adopting a greedy algorithm, by establishing a numerical simulation model of the exhaust duct acoustic lining deformation under the condition of the vacuum chuck, an association relationship between the number and layout of the vacuum chuck and the deformation of the exhaust duct acoustic lining and the vacuum chuck is established.

[0012] Adopting a greedy algorithm, by establishing a numerical simulation model of the exhaust duct acoustic lining deformation under the condition of the vacuum chuck, an association relationship between the number and layout of the vacuum chuck and the deformation of the exhaust duct acoustic lining and the vacuum chuck is established;

[0013] ;

[0014] Wherein:

[0015] is the configuration cost of the vacuum chuck;

[0016] is the number of vacuum chucks;

[0017] is the layout of the vacuum chuck;

[0018] is the relationship between the configuration cost of the vacuum chuck and its number and layout;

[0019] For the exhaust duct deformation and its tolerance;

[0020] For the vacuum chuck deformation and its tolerance;

[0021] For the optimal solution solved based on the greedy algorithm.

[0022] Preferably, it further includes a multi-spindle hole-making end effector connected to the acoustic lining support bottom plate. The multi-spindle hole-making end effector includes an actuator frame, a spindle group, a feed group, a solenoid valve group, and a pressure foot group. The actuator frame includes a front plate and a rear plate arranged oppositely. The spindle group, the feed group, and the solenoid valve group are all arranged in the inner cavity of the actuator frame. The pressure foot group is arranged on the rear plate and located outside the actuator frame. The feed group is arranged on the rear plate. One end of the spindle group corresponds to the feed group, and the other end passes through the front plate and is correspondingly connected to the pressure foot group. The feed group is used to control the extension or retraction of the corresponding spindle group and pressure foot group.

[0023] Preferably, it further includes a hole-making position error measurement system for measuring the angle between the equivalent machining hole-making direction of the multi-spindle hole-making end effector and the surface normal at the equivalent machining hole on the nacelle acoustic lining. 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 respectively used to measure the deviation between the Z-axis of the actual tool coordinate system and the Z-axis of the ideal tool coordinate system. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the Z-axis of the coordinate system is parallel to the hole-making direction.

[0024] Preferably, it further includes a hole-making direction deviation measurement system for measuring the position coordinates of the reference holes prefabricated on the nacelle acoustic lining and calculating the hole-making position errors at the position coordinates of each reference hole. The hole-making direction deviation measurement system includes a vision unit installed on the multi-spindle hole-making end effector. The vision unit includes a light source for providing good shooting lighting conditions, an industrial camera for measuring the actual position coordinates of the reference holes, and a telecentric lens. The direction of the light source is parallel to the direction of the spindle group.

[0025] Preferably, it includes an ultrasonic sensor group for anti-collision detection. The ultrasonic sensor group includes four ultrasonic sensors, and the four ultrasonic sensors are respectively installed at the four corners of the front plate.

[0026] Preferably, the spindle group includes n spindles, the feed group includes n cylinders, and the pressure foot group includes n pressure feet. n is an even number greater than 0. Each spindle, cylinder, and pressure foot are arranged in one-to-one correspondence. Each cylinder independently controls the extension and retraction of the corresponding spindle and pressure foot;

[0027] The solenoid valve group includes n + 1 solenoid valves. Each solenoid valve has two interfaces, namely an air inlet and an air outlet. n solenoid valves are used to control the extension and retraction of the cylinder, and the other solenoid valve is used for the control of the spindle air cooling switch;

[0028] Between each presser foot and the front plate, there is a spring for pressing the presser foot against the surface of the sound lining perforated panel. The spring is correspondingly sleeved on the outer periphery of the spindle.

[0029] Preferably, it also includes a vacuum tube group for vacuum collecting the chips generated during the hole-making process of the sound lining holes from the presser foot. The vacuum tube group includes n vacuum tubes, and each vacuum tube is correspondingly installed on the side of the presser foot. By adopting the foregoing design scheme, the beneficial effects of the present invention are as follows: The exhaust duct sound lining positioning tooling for the sound lining hole-making of the aeroengine nacelle of the present invention can achieve the flexible and efficient positioning of the exhaust duct sound lining of the aeroengine nacelle, provide conditions for the automatic and precise hole-making of the exhaust duct sound lining, and can also provide a reference for the design of other sound lining part positioning toolings, and provide technical support for the formulation of relevant design and development specifications or standards. Brief Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the robot multi-spindle hole-making control system in the present invention;

[0031] Figure 2 It is an axonometric view of the robot multi-spindle hole-making system in the present invention;

[0032] Figure 3 It is a front view of the robot multi-spindle hole-making system in the present invention;

[0033] Figure 4 It is a side view of the robot multi-spindle hole-making system in the present invention;

[0034] Figure 5 It is a top view of the robot multi-spindle hole-making system in the present invention;

[0035] Figure 6 It is an axonometric view of the multi-spindle hole-making end effector in the present invention;

[0036] Figure 7 It is a front view of the multi-spindle hole-making end effector in the present invention;

[0037] Figure 8 It is a top view of the multi-spindle hole-making end effector in the present invention;

[0038] Figure 9 It is a side view of the multi-spindle hole-making end effector in the present invention;

[0039] Figure 10 It is an axonometric view of the exhaust duct sound lining positioning tooling in the present invention (front view);

[0040] Figure 11 Isometric view (rear view) of the exhaust duct acoustic lining positioning tooling in the present invention;

[0041] Figure 12 Front view of the exhaust duct acoustic lining positioning tooling in the present invention;

[0042] Figure 13 Side view of the exhaust duct acoustic lining positioning tooling in the present invention;

[0043] Figure 14 Top view of the exhaust duct acoustic lining positioning tooling in the present invention;

[0044] In the figure:

[0045] Industrial robot 1, robotic arm 2, multi-spindle hole-making end effector 3, effector frame 31, first side plate 311, second side plate 312, spindle group 32, feed group 33, solenoid valve group 34, valve island 341, presser foot group 35, spring 351, ultrasonic sensor group 36, laser displacement sensor group 37, vision unit 38, vacuum tube group 39, exhaust duct acoustic lining positioning tooling 4, rotary transfer station platform 41, bottom mounting seat 411, transmission mechanism 412, top support seat 413, support frame 42, triangular support frame 421, annular support pipe 422, acoustic lining support bottom plate 43, mounting hole 431, vacuum suction cup 44. Detailed implementation manners

[0046] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0047] Refer to Figures 1 to 14 :

[0048] This embodiment proposes a control system for hole-making of the acoustic lining of an aero-engine nacelle, including a robot control system, a PLC control system, a host computer, a robot multi-spindle hole-making system, a hole-making direction deviation measurement system, and a hole-making position error measurement system. The robot multi-spindle hole-making system includes an industrial robot 1, a robotic arm 2 movably connected to the industrial robot 1, and a multi-spindle hole-making end effector 3 provided at the end of the robotic arm 2.

[0049] The robot control system is used for the motion and logic control of the industrial robot 1 and the real-time feedback of its pose and joint angles.

[0050] 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, realizing the motion, logic control, and status feedback of industrial robot 1. Meanwhile, it also realizes the motion, logic control, and status feedback of the multi-spindle hole-making end effector 3.

[0051] The upper computer is the human-machine interaction interface. By installing the robot control system on the upper computer, the import and execution of the G-code for the core hole-making process are realized. By calling communication libraries such as HSL Communication, the communication between the upper computer and the PLC control system is achieved, realizing the manual control of the multi-spindle hole-making end effector 3, and displaying and storing the motion state data of industrial robot 1 and multi-spindle hole-making end effector 3.

[0052] The hole-making position error measurement system is a laser displacement sensor group 37 installed on the multi-spindle hole-making end effector 3 (which will be introduced in detail below), measuring the angle between the hole-making direction of the equivalent processed hole of the multi-spindle hole-making end effector 3 and the surface normal at the equivalent processed hole on the nacelle acoustic lining.

[0053] The hole-making position error measurement system is a vision unit 38 installed on the multi-spindle hole-making end effector 3 (which will be introduced in detail below), measuring the position coordinates of the prefabricated reference holes on the nacelle acoustic lining, and then obtaining the hole-making position error at the positions of each reference hole in the product coordinate system of the nacelle acoustic lining.

[0054] Preferably, the multi-spindle hole-making end effector 3 is connected to the robotic arm 2 through a flange. The multi-spindle hole-making end effector 3 includes an actuator frame 31, a spindle group 32, a feed group 33, a solenoid valve group 34, a pressure foot group 35, an ultrasonic sensor group 36, a laser displacement sensor group 37, and a vision unit 38; the actuator frame 31 is the installation basis for each component in the multi-spindle hole-making end effector 3.

[0055] The actuator frame 31 has a cubic frame structure. Define two opposite side plates of the actuator frame 31 as the first side plate 311 and the second side plate 312. The pressure foot group 35, the ultrasonic sensor group 36, the laser displacement sensor group 37, and the vision unit 38 are all arranged on the first side plate 311. The feed group 33 and the solenoid valve group 34 are both arranged on the second side plate 312. The spindle group 32 is arranged inside the actuator frame 31, and one end passes through the first side plate 311 and is correspondingly connected to the pressure foot group 35. The feed group 33 is used to control the extension or retraction of the corresponding spindle group 32 and the pressure foot group 35.

[0056] Furthermore, the main spindle group 32 is composed of n main spindles in an array form, the feeding group 33 is composed of n cylinders in an array form, and the presser foot group 35 is composed of n presser feet in an array form. n is an even number greater than 0. The numbers of the main spindle group 32, the feeding group 33, and the presser foot group 35 are the same, and each main spindle, cylinder, and presser foot are arranged in one-to-one correspondence. The cylinders are respectively used to control the extension and retraction of the corresponding main spindle and presser foot. Preferably, a spring 351 for pressing the presser foot against the surface of the acoustic lining perforated panel is arranged between each presser foot and the first side plate 311, and each spring 351 is respectively sleeved on the outer periphery of the main spindle. Driven by each cylinder, the presser foot extends and under the pressure of the spring, presses against the surface of the acoustic lining perforated panel based on the friction force between the end face of the presser foot and the surface of the perforated panel. In this embodiment, the acoustic lining part and the end effector 3 for hole making on the main spindle are coupled into a whole to improve the stiffness of the hole making system and the hole making stability and reduce the vibration during the hole making process.

[0057] In this embodiment, n = 6.

[0058] Furthermore, the multi-main-spindle end effector 3 for hole making further includes a vacuum tube group 39. The vacuum tube group 39 is composed of n vacuum tubes in an array form. Each vacuum tube is installed on the side of the presser foot. Based on the principle of vacuum chip collection, the chips generated during the hole making process of the acoustic lining holes are collected from the presser foot to a dust collector (not shown in the figure).

[0059] Furthermore, the solenoid valve group 34 is composed of n + 1 solenoid valves in an array form. Each solenoid valve includes two interfaces, an air inlet and an air outlet. Among them, n solenoid valves are used to control the extension and retraction of the cylinders in the cylinder array, and the other 1 solenoid valve is used for the control of the main spindle air cooling switch. Preferably, a valve island 341 for installing the solenoid valve group 34 is also arranged on the second side plate 312. The valve island 341 can realize the independent control of the solenoid valves in the solenoid valve group 34 based on the same air source.

[0060] The ultrasonic sensor group 36 includes four ultrasonic sensors respectively used for anti-collision detection. The four ultrasonic sensors are evenly installed at the four corners of the first side plate 311.

[0061] The laser displacement sensor group 37 includes four laser displacement sensors respectively used for measuring the deviation between the actual tool coordinate system Z-axis (the axis parallel to the hole making direction) and the ideal tool coordinate system Z-axis. The four laser displacement sensors are evenly installed at the four corners of the first side plate 311 to provide a basis for the attitude correction of the end effector.

[0062] The vision unit 38 includes a light source for providing good shooting lighting conditions, an industrial camera and a telecentric lens for measuring the actual position coordinates of the reference holes. The optical axis direction is parallel to the main axis directions on the main shaft group 32. The light source is used to provide good shooting lighting conditions, and the industrial camera and the telecentric lens are used to measure the actual position coordinates of the reference holes. With the help of the hole-making direction deviation measurement system, the object distance and the optical axis direction during the measurement of the industrial camera are controlled. After calculating the deviations 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 the position correction of the end effector.

[0063] This embodiment further includes an exhaust duct acoustic lining positioning tooling 4 connected to the multi-spindle hole-making end effector 3. The exhaust duct acoustic lining positioning tooling 4 includes a rotary transfer station platform 41, a support frame 42, an acoustic lining support bottom plate 43, and vacuum suction cups 44.

[0064] The rotary transfer station platform 41 includes a bottom mounting base 411, a transmission mechanism 412 composed of an external gear ring and a gear, and a top support base 413. Among them, the bottom mounting base 411 is used to install the rotary transfer station platform 41 on the factory floor, the top support base 413 is used to install the support frame 42, and the transmission mechanism 412 composed of the external gear ring and the gear is used to realize the relative rotation of the top support base 413 relative to the bottom mounting base 411.

[0065] The support frame 42 is composed of a triangular support frame 421 and a plurality of annular support pipes 422. Among them, the triangular support frame 421 is the main support structure, and the annular support pipe 422 is an auxiliary back support part of the acoustic lining support bottom plate 43. The two are combined to realize the support of the entire acoustic lining support bottom plate 43.

[0066] The acoustic lining support bottom plate 43 is designed by copying the inner shape of the exhaust duct acoustic lining. Based on the mechanical connection method, the acoustic lining support bottom plate 43 is installed on the support frame 42. A plurality of approximately evenly distributed vacuum suction cup mounting holes 431 are designed on the acoustic lining support bottom plate 43. The vacuum suction cups 44 are installed in the mounting holes 431 of the acoustic lining support bottom plate 43. In a one-sided fixing manner, the suction side of the vacuum suction cup 44 is used to realize the multi-point flexible support of the acoustic lining, and the other side is used to connect the vacuum suction cup 44 to the acoustic lining support bottom plate 43, and the axial position of the vacuum suction cup 44 in the mounting hole 431 can be adjusted by a nut.

[0067] Furthermore, the number of vacuum suction cups 44 directly affects the cost investment and system complexity. The following method is used for optimization: taking the lowest configuration cost of the vacuum suction cups 44 as the goal, taking the number and layout of the vacuum suction cups 44 as the design variables, and taking the deformation of the exhaust duct acoustic lining and the vacuum suction cups 44 as the constraint conditions, an optimization model for the number and layout of the vacuum suction cups 44 as shown in the following formula is established;

[0068] SA1. Adopt the greedy algorithm to solve the optimal number and layout of the vacuum suction cups 44. Among them, by establishing a numerical simulation model of the exhaust duct acoustic lining deformation under the condition of the vacuum suction cups 44, establish the correlation between the number and layout of the vacuum suction cups 44 and the deformation of the exhaust duct acoustic lining and the vacuum suction cups 44;

[0069] (A1);

[0070] Among them: is the configuration cost of the vacuum suction cups 44;

[0071] is the number of the vacuum suction cups 44;

[0072] is the layout of the vacuum suction cups 44;

[0073] is the relationship between the configuration cost of the vacuum suction cups 44 and its number and layout;

[0074] is the exhaust duct deformation and its tolerance;

[0075] is the deformation of the vacuum suction cups 44 and its tolerance;

[0076] is the optimal solution obtained by the greedy algorithm, including the optimal number of the vacuum suction cups 44 and the optimal layout ;

[0077] SA2. The steps of the exhaust duct acoustic lining positioning tooling 4 for positioning and changing stations of the exhaust duct acoustic lining are as follows:

[0078] SA21. According to the area to be machined of the exhaust duct acoustic lining, through the rotary station-changing platform 41 of the exhaust duct acoustic lining positioning tooling, adjust the relative position between the exhaust duct acoustic lining and the machining robot to expand the machinable space of the machining robot;

[0079] SA22. According to the optimal number of the vacuum suction cups 44 and the optimal layout , design the mounting holes 431 of the vacuum suction cups 44 on the acoustic lining support bottom plate 43;

[0080] Install the vacuum suction cups 44 in the mounting holes 431, and finely adjust the position of the vacuum suction cups 44 in the axial direction of the mounting holes 431 so that the exhaust duct acoustic lining is in close contact with the acoustic lining support bottom plate 43 in the vacuum adsorption state. Pneumatic vacuum suction cups 44 are used to achieve multi-point adsorption and fixation of the exhaust duct acoustic lining through negative pressure, so as to prepare for the machining robot to perform acoustic lining hole machining.

[0081] The host computer controls the PLC control system. The PLC control system sends instructions to the industrial robot 1, driving the multi-spindle hole-making end effector 3 to reach the initially pre-specified position. The measurement coordinate system is moved to coincide with the pose of the nominal coordinate system of the reference hole, and the obtained pose information is transmitted to the PLC control system. The PLC control system compares the actual position coordinates of the reference hole obtained with the nominal coordinates of the reference hole, reads the data of each laser ranging sensor through the I / O module, calculates the pose deviation matrix of the tool coordinate system, determines the pose adjustment instruction and sends it to the multi-spindle hole-making end effector 3. The multi-spindle hole-making end effector 3 adjusts its pose according to the pose adjustment instruction. When the multi-spindle hole-making end effector 3 moves to the target machining pose, the PLC control system drives the industrial robot 1 to move to eliminate the hole-making direction deviation at the target machining position. After the multi-spindle hole-making end effector 3 reaches the target machining pose, the pose of the industrial robot 1 is locked. The PLC control system sends a drilling instruction to the multi-spindle hole-making end effector 3, and the multi-spindle hole-making end effector 3 performs drilling after receiving the drilling instruction. After the drilling operation is completed, it feeds back to the PLC control system, and the PLC control system sends an instruction to control the industrial robot 1 to drive the multi-spindle hole-making end effector 3 to return to the above pre-specified position, completing one operation process.

[0082] The host computer generates hole machining process information according to the hole position design information and sends it to the PLC control system (lower computer); receives the pose information sent by the industrial camera through the communication layer, determines that the industrial robot 1 eliminates the hole-making direction deviation at the target machining position, and sends this direction deviation to the lower motion control layer.

[0083] This embodiment also proposes a control method for hole-making of the acoustic liner of an aeroengine nacelle, which is carried out according to the following steps:

[0084] S1, the host computer calls the communication library to control the PLC control system;

[0085] 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;

[0086] The host computer controls the industrial camera to take an image of the reference hole and calculates and obtains the actual position coordinates of the reference hole;

[0087] Based on the actual position coordinates of the reference hole and the origin of the nominal coordinate system of the reference hole, calculate the position error of each reference hole, and then calculate the hole-making position error of the position to be machined within the enclosed area of each reference hole through interpolation compensation;

[0088] Among them, the hole-making position error is carried out according to the following steps:

[0089] S11, use the vision unit integrated on the end effector of the robot multi-spindle hole-making system to take an image of the reference hole;

[0090] Among them, it is defined that the optical axis of the camera is parallel to the axis of the main axis array, and the object distance during visual shooting as well as the perpendicularity of the optical axis to the surface of the acoustic lining are obtained to get the pose of the vision unit under the condition of the orthographic object distance and the perpendicular state of the optical axis to the surface of the acoustic lining;

[0091] (1);

[0092] Among them:

[0093] is the coordinate system of the vision unit relative to the coordinate system of the nacelle acoustic lining product pose;

[0094] is the calibrated robot base coordinate system relative to the product coordinate system pose;

[0095] is the pose of the robot flange coordinate system relative to the robot base coordinate system pose;

[0096] is the calibrated robot tool coordinate system relative to the flange coordinate system pose;

[0097] is the calibrated hand-eye relationship, that is, the coordinate system of the vision unit relative to the tool coordinate system pose;

[0098] represents the orthographic object distance;

[0099] represents that the optical axis is perpendicular to the surface of the acoustic lining, that is, the angle is 90°;

[0100] S12, passing through S11, the robust, accurate and efficient positioning of the reference hole feature in the reference hole image is obtained by the reference hole feature positioning algorithm combining visual saliency and mean shift. The specific steps are as follows:

[0101] S121, perform Gaussian filtering or median filtering on the obtained original reference hole image to obtain the corresponding smoothed image ; perform image contrast stretching on the smoothed image to obtain the enhanced image , calculate the saliency map of the original reference hole image according to formula (2) ;

[0102] (2);

[0103] where:

[0104] represents calculating the average pixel value of the image:

[0105] represents obtaining the maximum pixel value of the image;

[0106] represents obtaining the minimum pixel value of the image;

[0107] S122, through region screening, select the saliency map of the reference hole image and obtain the centroid coordinates of the largest saliency region by selecting the saliency region with the largest area in it , calculate the distance map between the coordinates of each pixel position in the saliency map and the centroid coordinates according to formula (3) ; ;

[0108] Calculate the weight map according to formula (4) ;

[0109] According to formula (5), the weight map is multiplied by the corresponding elements of the saliency map to remove the fragmented saliency regions in the saliency map and obtain the updated saliency map ;

[0110] (3);

[0111] (4);

[0112] (5);

[0113] S123, based on the automatic threshold segmentation method or by repetitive testing, select an appropriate fixed threshold to perform threshold segmentation on the updated saliency map in S122 and segment the reference hole feature region from the saliency map;

[0114] Use an edge detection operator or a contour extraction algorithm to extract the reference hole contour from the threshold segmentation map of the saliency map, approximately evenly divide the set of contour points into three consecutive subsets, randomly select contour points from the three subsets multiple times for circle fitting, and store all the fitted center coordinates in an array;

[0115] From all the alternative centroids, randomly select one as the initial centroid. With this as the center and based on a preset scanning radius, use the mean shift algorithm to iteratively find the true centroid of the set of centroids as the coordinate system of the reference hole center. ;

[0116] S13. Set the image coordinate system at the center of the image, with its coordinate axis directions the same as the default coordinate axis directions of the image. According to the reference hole center coordinates obtained in S12, combined with the calibrated internal parameters of the vision unit and the known image width and height ;

[0117] Define the XY plane of the vision unit coordinate system and its coordinate axes to coincide with the image coordinate plane and its coordinate axes correspondingly. According to formula (6), obtain the physical coordinates of the reference hole in the vision unit coordinate system ;

[0118] (6);

[0119] According to formula (7), combined with obtained in S1, obtain the homogeneous transformation matrix expression of the reference hole in the product coordinate system , which consists of the rotation matrix and the translation vector ;

[0120] The transpose of the translation vector is the coordinate of the reference hole measured by the vision unit in the product coordinate system ;

[0121] (7);

[0122] Combine with the nominal coordinate of the reference hole in the product coordinate system to obtain the hole-making positioning error at the reference hole ;

[0123] (8);

[0124] S14. For all the reference holes, repeat steps S11 to S13 to measure the hole-making positioning errors at all the reference holes through the vision system;

[0125] S15. Through surface interpolation, obtain the hole-making positioning errors at the positions of the remaining holes to be made within the influence area of the reference holes, and compensate for these errors;

[0126] S2. The host computer calls the communication library to control the PLC control system;

[0127] 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 pose;

[0128] The PLC control system reads the data of each laser ranging sensor through the I / O module, obtains the hole-making direction deviation through the calculation algorithm, and then calculates the pose deviation matrix of the tool coordinate system;

[0129] S3. According to the hole-making position error of the to-be-machined position obtained in S1, update and save the hole-making position coordinates in the current acoustic lining hole. 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 pose;

[0130] According to the pose deviation matrix of the tool coordinate system obtained in S2, based on this deviation matrix, the PLC control system drives the industrial robot to move to eliminate the hole-making direction deviation at the target machining position;

[0131] After the multi-spindle hole-making end effector reaches the target machining pose, lock the pose of the industrial robot. The PLC control system drives the rotation of each independent control spindle of the multi-spindle hole-making end effector and the extension of the pressure foot and the spindle to complete the machining of the acoustic lining hole;

[0132] S4. After the hole-making is completed, the PLC control system controls the spindle and the pressure foot to retract, and moves the industrial robot to the next target machining pose for the machining of the next hole; until all the acoustic lining holes in the hole-making area are machined, the PLC control system drives the industrial robot to move to a safe position and closes each hole-making spindle.

[0133] By adopting the foregoing design scheme, the beneficial effects of the present invention are as follows: The control system and control method for the acoustic lining hole-making of the aero-engine nacelle of the present invention can realize the flexible, high-quality and high-efficiency machining of large-scale noise-reducing acoustic lining holes in the nacelle, and realize the accurate measurement of the hole-making positioning error, thereby shortening the manufacturing cycle of the aero-engine nacelle acoustic lining parts and providing a theoretical basis and technical support for the formulation of the hole-making process specifications of the aero-engine nacelle acoustic lining.

[0134] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle, characterized by: It includes a rotary station switching platform and a sound liner support bottom plate arranged on the rotary switching station platform, a support frame for supporting the sound liner support bottom plate, and a vacuum suction cup arranged on the sound liner support bottom plate. The sound liner support bottom plate is adapted to the inner shape of the sound liner of the exhaust duct, and an arc-shaped portion protrudes outward from the middle thereof. The support frame includes a triangular support frame for supporting the periphery of the sound liner support bottom plate and a plurality of annular support tubes for supporting the arc-shaped portion, and each annular support tube is adapted to the arc-shaped portion. Optimal number of vacuum cups and optimal layout The calculation of is as follows: A greedy algorithm is used to establish a numerical simulation model of the deformation of the exhaust duct acoustic liner under the condition of a vacuum chuck, and the correlation between the number and layout of the vacuum chuck and the deformation of the exhaust duct acoustic liner and the vacuum chuck is established. ； in: Assign cost to vacuum cups; is the number of vacuum cups; Layout for vacuum suction cups; Configure the relationship between the cost of vacuum cups and their number and layout; Exhaust duct deformation and its tolerance; The deformation of the vacuum cup and its tolerance; It is the optimal solution based on the greedy algorithm.

2. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 1, characterized in that: The rotary station-changing platform includes a bottom mounting seat, a top supporting seat, and a transmission mechanism for driving the top supporting seat to rotate relative to the bottom mounting seat. The transmission mechanism is arranged between the bottom mounting seat and the top supporting seat, the support frame is arranged on the top supporting seat, and the transmission mechanism includes an outer gear ring and a gear.

3. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 1, characterized in that: A plurality of mounting holes compatible with the vacuum suction cup are arranged on the sound liner support base plate, and the vacuum suction cup is arranged in the mounting hole. The suction cup side of the vacuum suction cup is used to realize multi-point flexible support of the sound liner, and the other side is used to connect the vacuum suction cup to the sound liner support base plate, and the axis position in the mounting hole of the vacuum suction cup can be adjusted by a nut.

4. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 1, characterized in that: It also includes a multi-spindle hole-making end effector, which includes an actuator frame, a spindle group, a feed group, a solenoid valve group and a presser foot group; the actuator frame includes a front plate and a rear plate arranged opposite to each other, the spindle group, the feed group and the solenoid valve group are all arranged in the inner cavity of the actuator frame, the presser foot group is located outside the actuator frame, the feed group is arranged on the rear plate, one end of the spindle group is arranged corresponding to the feed group, and the other end passes through the front plate and is connected to the presser foot group accordingly, and the feed group is used to control the extension or retraction of the corresponding spindle group and the presser foot group.

5. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 4, characterized in that: It also includes a hole making position error measurement system for measuring the angle between the hole making direction of the equivalent processing hole of the multi-spindle hole making end effector and the surface normal of the equivalent processing 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 respectively used to measure the deviation between the Z axis of the actual tool coordinate system and the Z axis of the ideal tool coordinate system. The four laser displacement sensors are respectively installed at the four corners of the front plate, and the Z axis of the coordinate system is parallel to the hole making direction.

6. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 5, characterized in that: It also includes a hole making direction deviation measurement system for calculating the hole making position error at the position coordinates of each reference hole. The hole making direction deviation measurement system includes a visual unit installed on the multi-spindle hole making end effector. The visual unit includes a light source for providing good shooting lighting conditions and an industrial camera and a telecentric lens for measuring the actual position coordinates of the reference hole. The direction of the light source is parallel to the direction of the spindle group.

7. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 5, characterized in that: The ultrasonic sensor group includes four ultrasonic sensors for anti-collision detection. The four ultrasonic sensors are respectively installed at four corners of the front plate.

8. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 5, characterized in that: 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 arranged 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. The solenoid valve group includes n+1 solenoid valves, each of which includes 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 to control the spindle air cooling switch; A spring for pressing the presser foot against the surface of the acoustic lining perforated panel is arranged between each presser foot and the front plate, and the spring is correspondingly sleeved on the outer peripheral edge of the main shaft.

9. The exhaust duct acoustic lining positioning tool for making holes in the acoustic lining of an aircraft engine nacelle according to claim 5, characterized in that: It also includes a vacuum tube group for collecting the chips generated in the process of making the acoustic lining holes by vacuum at the presser foot. The vacuum tube group includes n vacuum tubes, and each vacuum tube is correspondingly installed on the side of the presser foot.

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