A method for controlling the tightening of an aircraft engine rotor based on bolt preload force feedback and an automated tightening equipment

Abstract

The present invention belongs to the field of tightening control methods and automated tightening technology, and discloses an aircraft engine rotor tightening control method and automated tightening equipment based on bolt pre-tightening force feedback. The automated tightening equipment is based on a main structure, and is provided with a turntable mechanism, a ball guide mechanism, and a slide mechanism to realize the freedom of movement of the aircraft engine rotor automated tightening equipment in the rotor cavity space, so that the tightening mechanism can enter and exit; a pre-tightening force detection mechanism is also provided, which relies on an ultrasonic pre-tightening force test system to measure the real-time pre-tightening force of the bolt during the tightening process, and transmit the pre-tightening force value to the tightening gun to realize a tightening method of pre-tightening force feedback control. The characteristics of the present invention are that it can realize the real-time pre-tightening force feedback during the tightening process, and realize the precise control of the target pre-tightening force; the automated tightening equipment can solve the problems of narrow entrance and poor operability of the internal structure of the aircraft engine rotor, realize automated tightening, and improve tightening efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of tightening control methods and automated tightening, and relates to an aero-engine rotor tightening control method based on bolt pre-tightening force feedback and automated tightening equipment. Background Art

[0002] The assembly quality of the rotor connection bolts directly affects the overall performance of the aircraft engine. The internal structure of the aircraft engine rotor is complex, the entrance is narrow and the entry depth is large. At the same time, the radial distance from the bolt to the rotor rotation center is large, which brings great difficulties to the assembly. At present, manual mechanical tooling or equipment with a low degree of automation is mainly used to tighten the bolts in the assembly of the engine rotor. The assembly efficiency is low, the labor intensity of the workers is high, and the assembly quality is difficult to guarantee, and the assembly consistency is not ideal. At the same time, the bolts are currently tightened by manual tightening through a single torque method, with the help of a torque wrench. The tightening efficiency is low, the tightening quality is difficult to guarantee, and the preload deviation of the tightening bolts can reach 25%-50%. These problems restrict the improvement of the rotor assembly quality to a certain extent, thereby affecting the performance of the aircraft engine.

[0003] Zhao Bing et al. published a method in the patent "A method for accurately controlling the pre-tightening force of aircraft engine bolts" to characterize the actual pre-tightening force of the bolt by the deformation of the bolt, apply a tensile force F to the bolt with a tensile machine, use the ultrasonic echo method to measure the bolt echo time T0 before stretching and the bolt echo time T1 after being stretched by the tensile force F, use the tensile force as the pre-tightening force, establish a pre-tightening force-acoustic time difference curve, realize the low error rate calibration of the bolt pre-tightening force, and realize the accurate control of the pre-tightening force under different process parameters. However, the tightening method still adopts the manual form, and the automatic tightening is not realized. In addition, the ultrasonic echo is only used for the calibration of the pre-tightening force, and the closed-loop control of the pre-tightening force is not realized. Li Xiaoqiang et al. published a device for automatically tightening the blind cavity nuts of aircraft engine compressor rotors in the patent "An automatic tightening device and method for blind cavity nuts of aircraft engine compressor rotors", which realizes the automation of the tightening process and nut supply, and the visualization of the tightening state, so as to improve the tightening efficiency and tightening accuracy, but the controlled tightening process is still an open-loop process, which will still produce a large pre-tightening force deviation.

[0004] In order to improve the assembly quality of the engine, it is necessary to study the tightening control method of the bolts and the automated assembly equipment. In view of the problem of preload deviation, the causes of deviation in the existing tightening control method are analyzed, and a tightening control method to reduce the preload deviation is proposed. In view of the problem of difficulty in tightening the complex structure of the rotor, low assembly efficiency and poor quality, the specific structure of the rotor is analyzed, and automated tightening equipment is designed to achieve efficient and high-quality tightening of the bolts and improve assembly performance. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of large dispersion of the tightening pre-tightening force of the existing aero-engine rotor, and to provide an aero-engine rotor feedback tightening control method and an automated tightening device. The tightening device can detect its pre-tightening force in real time, compare the current value with the given pre-tightening force, and realize the control of the motor speed, thereby controlling the tightening of the motor. The present invention can carry out tightening work in the narrow space of the aero-engine, and utilizes the feedback tightening control method to effectively reduce the deviation of the pre-tightening force and ensure the tightening consistency.

[0006] The technical solution of the present invention:

[0007] An automated tightening device for an aircraft engine rotor based on bolt pre-tightening force feedback, comprising a main structure 30, a turntable structure 31, a ball guide rail structure 32, a slide structure 33, a tightening structure 34, a connected part structure 35, and an ultrasonic pre-tightening force detection system 36;

[0008] The main structure 30 is mainly composed of support legs 2, a device base 3, support columns 4, and a platform plate 9. The four support legs 2 are fixed on the device base 3, the lower end of the support column 4 is fixed in the support legs 2, and the upper end of the support column 4 is fixed with a platform plate 9;

[0009] The connected structure 35 is mainly composed of a base bottom plate 5, a base 6 and a rotor 7. The four bases 6 are cylindrical, the lower ends of which are fixed on the base bottom plate 5, and the upper ends of which are connected to the rotor 7. The connected structure 35 is fixed to the center of the device base 3 through the base bottom plate 5, and realizes the counter-torque of the automated tightening equipment.

[0010] The turntable structure 31 includes a turntable motor 10 and a turntable 11, and the turntable 11 is connected to the turntable motor 10 to realize the rotation of the tightening device;

[0011] The ball guide rail structure 32 is mainly composed of a ball screw 18, a ball guide rail 19 and a guide rail plate 20. The turntable 11 is connected to the platform plate 9 at the bottom and the guide rail plate 20 at the top. There are two ball guide rails 19 and a ball screw 18 on the guide rail plate 20. The feeding and retreating actions of the tightening structure 34 can be realized by shaking the handle 28.

[0012] The slide structure 33 is mainly composed of a slide motor 12, a slide 13, a slide back plate 14 and a slide plate 15. A slide base plate 16 is connected to the slider of the ball guide 19 and the ball screw 18. The slide base plate 16 is connected to the slide 13 and the slide back plate 14. The top of the slide 13 is connected to the slide motor 12. The slide 13 is also connected to the slide plate 15 to realize the lifting movement of the tightening structure 34.

[0013] The tightening structure 34 is mainly composed of a tightening motor 21, a reducer 22, a transverse gear box 23 and a tightening sleeve 24. The end of the transverse gear box 23 is connected to the tightening sleeve 24. One end of the reducer 22 is connected to the tightening motor 21, and the other end is connected to the mounting plate 17 and the transverse gear box 23. The mounting plate 17 is connected to the slide plate 15 through the through hole on the guide plate 20.

[0014] The ultrasonic preload force detection system 36 is mainly composed of an ultrasonic probe 25, an oscilloscope 26 and a PC module 27 connected in sequence; wherein the PLC module and the PC module 27 communicate with each other via a network cable in the form of ModbusTCP, the PC module 27 and the oscilloscope 26 are connected via a network cable, and the ultrasonic probe 25 is connected to the oscilloscope (26), thereby realizing mutual communication between the oscilloscope 26 and the PC module 27, and between the PC module 27 and the PLC module. When in use, the ultrasonic probe 25 needs to be manually pressed against the bolt head of the bolt 8 to be tightened, and the actual value of the preload force detected by the ultrasonic probe 25 can be transmitted to the PLC module.

[0015] The automated tightening equipment also requires a set of automated control operating systems, including an HMI touch screen, a PLC module, a servo motor, a servo drive, a 24V DC power supply, cables, etc.; the servo motors include: a turntable motor 10, a slide motor 12, and a tightening motor 21; the HMI touch screen is connected to the PLC module via a network cable to achieve human-computer interaction; the PLC module is powered by a 24V DC power supply; the PLC module is respectively connected to the servo drive, the HMI touch screen, and the ultrasonic preload force detection system 36; the servo drive is powered by a 220V power supply, and the communication between the servo drive and the PLC module is achieved through a network cable; one end of the servo drive is connected to the PLC module, and the other end is connected to the next servo drive to achieve the control of multiple servo drives by the PLC module; at the same time, the servo drive is connected to the power line of the servo motor and the encoder line built into the servo motor to achieve control of the servo motor.

[0016] A method for controlling the tightening of an aero-engine rotor based on bolt pre-tightening force feedback comprises the following steps:

[0017] Step 1: Introduce vector control of the preload ring;

[0018] The tightening motor 21 is a permanent magnet synchronous motor. On the basis of the three-closed-loop vector control of the permanent magnet synchronous motor, a preload loop is introduced, and the preload loop and the position loop are combined into one loop, thereby obtaining a new three-closed-loop vector control method of the preload loop, the speed loop, and the current loop; the bolt 8 to be tightened is installed on the rotor 7, and in the new preload loop, an ultrasonic preload test method is used to detect the actual value of the preload force of the bolt 8 to be tightened in real time, and the preload force is fed back to the fuzzy PID controller. The controller calculates the required speed of the motor according to the difference between the expected value and the actual value and transmits it to the speed loop, thereby completing the control of the tightening process of the bolt 8 to be tightened;

[0019] At the same time, the ultrasonic preload force detection system 36 will continue to collect the actual value of the preload force of the bolt 8 to be tightened;

[0020] Step 2: Establish a tightening angle-preload force model based on the preload force feedback method of the permanent magnet synchronous motor;

[0021] The tightening angle-preload model is the feedback link of real-time preload, and its accuracy has an important impact on the design of the subsequent fuzzy PID controller and modeling and simulation verification;

[0022] In the torque-angle method, the connection stiffness is regarded as a constant, that is, the tightening angle and the preload are linearly related; however, in the actual tightening process, due to the influence of factors such as the surface roughness of the connection, the increase in preload shows nonlinearity as the tightening angle increases; the tightening angle-preload model is specifically expressed as:

[0023] (1)

[0024] In the formula, is the tightening angle, is the thread pitch, is the bolt preload, is the bolt stiffness, is the stiffness of the connected component, is the thread stiffness, , and are the thread stiffness, nut stiffness and bolt head stiffness affected by surface roughness. Formula (1) takes into account the nonlinearity of connection stiffness caused by surface roughness, and can more accurately describe the relationship between rotation angle and preload during tightening, providing a modeling basis for the tightening method of preload feedback control.

[0025] Step 3, designing a fuzzy PID controller based on the preload force feedback method;

[0026] Based on the three-closed-loop vector control method and the established tightening angle-preload model, a fuzzy PID controller is designed to achieve accurate control of the preload by taking the current actual value of the preload as feedback.

[0027] The ultrasonic preload force detection system 36 collects the actual preload force value of the bolt 8 to be tightened, compares it with the set final preload force value, and calculates the error value. Error change rate The fuzzy PID controller uses the error as input. Error change rate Fuzzification, and then the fuzzy control quantity is obtained through fuzzy rules. The fuzzy control quantity is then processed through non-fuzzy processing to obtain the actual control quantity, that is, the required speed value. The speed value is input into the speed loop to control the tightening of the motor.

[0028] Step 4: Build the experimental system;

[0029] The automated tightening equipment needs to simultaneously control the tightening motor 21, the slide 13, the turntable motor 10 of the turntable 11, and the slide motor 12, and also communicate with the ultrasonic preload force detection system 36 to obtain the actual value of the preload force of the bolt 8 to be tightened;

[0030] PLC module is selected as the control system. The control system is divided into hardware and software parts. The overall block diagram of the system is shown below. The tightening motor 21, the slide motor 12, the turntable motor 10 and the motion control program written by the user constitute the control layer; the PLC module, the ultrasonic preload detection system 36, the switch for adding the network cable interface, the servo motor, the servo driver and the 220V and 24V power supplies constitute the electrical layer of the overall system; the tightening structure 34, the slide structure 33 and the turntable structure 31 constitute the execution layer; the control layer is programmed by the user to set the final value of the preload and the movement speed for the turntable motor 10 and the slide motor 12, and the measured current real-time preload value is transmitted to the PLC module through the ultrasonic probe, and the fuzzy PID control method is used to specify the PLC module's processing of the preload value and the speed of the tightening motor 21 and the control of the tightening motor 21, that is, the conversion between the control layer and the electrical layer is realized through the PLC module; similarly, the rotation of the turntable motor 10 and the slide motor 12 is used to control the rotation and advance and retreat of the tightening structure 34, that is, the conversion from the electrical layer to the execution layer is realized through the servo motor and the servo driver;

[0031] The PLC module is powered by a 24V DC power supply. The PLC module needs to be connected to the servo driver, touch screen, and ultrasonic preload detection system 36 respectively. The servo driver used in the automatic control system is powered by a 220V power supply, and the communication between the servo driver and the PLC module is realized through a network cable. One end of the servo driver is connected to the PLC module, and the other end is connected to the next servo driver to realize the control of multiple servo drivers by the PLC module. At the same time, the servo driver needs to be connected to the power line and encoder line of the servo motor to realize the control of the servo motor.

[0032] At the same time, for the motor of the electric slide, if the power is suddenly cut off and the motor is disabled, the slide connection and tightening part may fall vertically and cause danger. Therefore, a servo motor with a brake function needs to be selected. Therefore, for this servo motor, in addition to the conventional connection with the servo driver, its servo motor brake line needs to be connected to the 24V power supply. The PLC module communicates with the ultrasonic test system through the network cable. At the same time, the preload measurement of the ultrasonic preload detection system 36 also requires the oscilloscope to be connected to the PC module 27 through the network cable. Therefore, a switch is used to increase the network cable interface to realize the mutual communication between the oscilloscope and the PC module 27, and the PC module 27 and the PLC module. In order to realize the touch screen used for human-computer interaction, it is necessary to be connected to the PLC module through a network cable. In this way, the preliminary construction of the automatic tightening control system is realized.

[0033] Step 5, tightening preparation stage;

[0034] When tightening the bolts 8 to be tightened on the aero-engine rotor, the rotor 7 is placed in the tightening position of the automated tightening equipment and fixed; after completing the positioning of the automated tightening equipment and the rotor 7, the automated tightening equipment drives the tightening structure 34 to move and enter the interior of the rotor from the entrance of the rotor 7; then the motion control program is used to control the tightening sleeve 24 to continue to move horizontally and rotate in space, thereby realizing the capping action of the tightening sleeve 24; then the ultrasonic probe 25 of the ultrasonic preload force detection system 36 is pressed against the bolt head of the bolt 8 to be tightened, thereby ensuring real-time measurement of the preload force.

[0035] Step 6: Tightening process with preload force feedback;

[0036] The tightening structure 34 is started to tighten the bolt 8 to be tightened; the ultrasonic pre-tightening force detection system 36 feeds back the real-time pre-tightening force to the tightening motor 21, and after the tightening bolt 8 is tightened to the pre-tightening force final value set by the user, the tightening process of the bolt 8 to be tightened is completed; after the tightening of a bolt 8 to be tightened is completed, the motion control program controls the tightening structure 34 to move upward to ensure that the tightening sleeve 24 is disengaged from the nut, and moves the tightening sleeve 24 to the next bolt 8 to be tightened through a rotational motion, and repeats the tightening action until all the bolts installed on the entire rotor 7 are tightened.

[0037] Beneficial effects of the invention: The invention provides an aero-engine rotor feedback tightening control method and an automated tightening device. Aiming at the problem of pre-tightening force dispersion in the assembly of aero-engine rotors, a pre-tightening force feedback control tightening method is proposed, which can effectively improve the pre-tightening force control accuracy, reduce the pre-tightening force dispersion, and realize tightening automation to improve efficiency.

[0038] One advantage of the present invention is that it provides an aero-engine rotor feedback tightening control method and an automated tightening device. The present invention can perform tightening operations on the drum bolts of a certain type of aero-engine rotor structure according to a set tightening sequence, effectively improving work efficiency and making operation more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the automated tightening equipment for aero-engine rotors according to the present invention.

[0040] Figure 2 This is a stereoscopic diagram of the main structure of the aero-engine rotor automated tightening equipment of the present invention.

[0041] Figure 3 It is a stereoscopic diagram of the partial structure of the aero-engine rotor automated tightening device according to the present invention.

[0042] Figure 4 This is a schematic diagram of the preload force testing system of the aero-engine rotor automated tightening equipment of the present invention.

[0043] Figure 5 This is a diagram of the ultrasonic probe assembly position of the aero-engine rotor feedback tightening control method described in the present invention.

[0044] Figure 6 This is a flow chart of the aircraft engine rotor feedback tightening control program described in the present invention.

[0045] Figure 7 The figure is an overall block diagram of the aero-engine rotor feedback tightening control system of the present invention.

[0046] Figure 8 This is a schematic diagram of the three-closed-loop vector control of the permanent magnet synchronous motor described in the present invention.

[0047] In the figure: 1 fastening bolts; 2 supporting feet; 3 device base; 4 supporting columns; 5 base bottom plate; 6 base; 7 rotor; 8 bolts to be tightened; 9 platform plate; 10 turntable motor; 11 turntable; 12 slide motor; 13 slide; 14 slide back plate; 15 slide plate; 16 slide bottom plate; 17 mounting plate; 18 ball screw; 19 slide guide; 20 guide plate; 21 tightening motor; 22 reducer; 23 transverse gear box; 24 tightening sleeve; 25 ultrasonic probe; 26 oscilloscope; 27 PC module; 28 handle; 30 main structure; 31 turntable structure; 32 ball guide structure; 33 slide structure; 34 tightening structure; 35 connected part structure; 36 ultrasonic preload detection system. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0049] like Figure 1-3As shown, an aero-engine rotor feedback tightening control method and an automated tightening device include a main structure 30, a turntable structure 31, a ball guide rail structure 32, a slide structure 33, a tightening structure 34, a connected part structure 35, and an ultrasonic preload force detection system 36.

[0050] The device base 3 is a square bottom plate, and four support legs 2 are arranged on the device base 3 by fastening bolts 1. Four support columns 4 are inserted into the four support legs 2 and fixed by top screws. At the same time, eight bolt holes are provided at the center of the device base 3 for fixing the base 6 of the rotor 7 to achieve the fixation of the engine rotor connector, determine the positional relationship between the rotor and the tightening system, and realize the counter-torque of the automatic tightening system. There are 48 bolts 8 to be tightened on the rotor.

[0051] The platform plate 9 and the four support columns 4 are connected by bolts to form a placement surface, and the turntable 11 is placed on this plane. Bolt holes are provided on the platform plate 9 and the turntable 11, and the turntable 11 is fixed to the platform plate 9 by bolt connection. In addition, the turntable 11 is connected to a motor 21 to drive the slide to rotate, thereby realizing the rotation function of the device.

[0052] The guide rail plate 20 is connected to the upper surface of the turntable 11 by bolt connection, and two ball guide rails 19 and a ball screw 18 are provided on the guide rail plate.

[0053] The slide base plate 16 is connected to the ball guide rail 19 and the ball screw 18 by bolt connection. The slide base plate 16 is connected to the slide back plate 14, and the slide 13 is connected to the slide base plate 16 and the slide back plate 14 respectively to achieve fixation. The top of the slide 13 is connected to the slide motor 12 to drive the slide. The slide plate 15 is connected to the mounting plate 17 with the tightening structure 34. In this way, the lifting, feeding and retreating functions of the tightening device are realized.

[0054] The tightening structure 34 includes a tightening motor 21, a reducer 22, a transverse gearbox 23 and a tightening sleeve 24. One end of the reducer 22 is connected to the tightening motor 21, and the other end is connected to the mounting plate 17 and the transverse gearbox. The motor and the reducer are both in the space surrounded by the mounting plate 17, and the end of the transverse gearbox 23 is connected to the tightening sleeve 24. The transverse gearbox is used here for two reasons. First, due to the limitation of the internal size of the rotor, the torque of the tightening gun cannot be directly output to the nut position of the tightening bolt, so a torque transmission mechanism is required to perform radial torque transmission. Second, the gear transmission has the advantages of relatively simple structure, relatively stable torque transmission, and simple control method of torque transmission.

[0055] The ultrasonic preload force detection system 36 includes an ultrasonic probe 25, an oscilloscope 26, and a PC module 27. Figure 4 shown.

[0056] In addition, an automated control operating system is required, including HMI touch screen, PLC module, servo motor, servo drive, 24V DC power supply, cables, etc.

[0057] The implementation steps of the present invention are:

[0058] Step 1: Introduce vector control of the preload ring;

[0059] The tightening motor 21 is a permanent magnet synchronous motor. On the basis of the three-closed-loop vector control of the permanent magnet synchronous motor, a preload loop is introduced, and the preload loop and the position loop are combined into a new preload loop, thereby obtaining a new three-closed-loop vector control method of a preload loop, a speed loop, and a current loop; the bolt 8 to be tightened is installed on the rotor 7, and in the new preload loop, an ultrasonic preload test method is used to detect the actual value of the preload force of the bolt 8 to be tightened in real time, and the actual value of the preload force is fed back to the fuzzy PID controller. The controller calculates the required speed of the motor according to the difference between the expected value and the actual value and transmits it to the speed loop, thereby completing the control of the tightening process of the bolt 8 to be tightened;

[0060] The ultrasonic preload force detection system 36 continues to collect the current bolt preload force.

[0061] Step 2, establishing a tightening mathematical model based on the preload force feedback method of the permanent magnet synchronous motor;

[0062] The tightening angle-preload model is the feedback link of real-time preload, and its accuracy has an important impact on the design of subsequent fuzzy PID controller and modeling simulation verification.

[0063] During the bolt tightening process, the relationship between the rotation angle and the preload force is shown in formula (2):

[0064] (2)

[0065] In the formula, is the tightening angle, is the thread pitch, is the bolt preload, is the bolt stiffness, is the stiffness of the connected component, is the thread stiffness, , and They are the thread stiffness, nut stiffness and bolt head stiffness affected by surface roughness. Formula (2) takes into account the nonlinearity of the connection stiffness caused by surface roughness, and can more accurately describe the relationship between the rotation angle and the preload during the tightening process, providing a modeling basis for the tightening method of preload feedback control.

[0066] Step 3: Design of fuzzy PID controller based on preload force feedback method;

[0067] Based on the vector control theory of three-phase permanent magnet synchronous motor and the established tightening angle-pretightening force model, a fuzzy PID controller is designed. The current actual value of the pretightening force is used as feedback to achieve accurate control of the pretightening force.

[0068] The ultrasonic preload detection system 36 collects the preload of the bolt 8 to be tightened, compares it with the final value of the preload set by the user, and calculates the error. Error change rate The fuzzy PID controller uses the error as input. Error change rate Fuzzification, then the fuzzy control quantity is obtained through fuzzy rules, and the fuzzy control quantity is then processed through non-fuzzy processing to obtain the actual control quantity, that is, the required speed, which is input into the speed loop to control the tightening of the motor;

[0069] Step 4: Build the experimental system;

[0070] The automated tightening equipment controls the tightening motor 21, the slide 13, the turntable motor 10 of the turntable 11, and the slide motor 12 at the same time, and the control system needs to communicate with the ultrasonic preload force detection system 36 to input the collected actual value of the preload force of the bolt 8 to be tightened into the control system;

[0071] The PLC module is selected as the control system. The control system is divided into hardware and software parts. The overall block diagram of the system is shown below. The tightening motor 21, the slide motor 12, the turntable motor 10 and the motion control program written by the user constitute the control layer; the PLC module, the ultrasonic preload detection system 36, the switch for adding the network cable interface, the servo motor, the servo driver and the 220V and 24V power supplies constitute the electrical layer of the overall system; the tightening structure 34, the slide structure 33 and the turntable structure 31 constitute the execution layer. The control layer is programmed by the user to set the final value of the preload and the movement speed for the turntable motor 10 and the slide motor 12. The measured current real-time preload value is transmitted to the PLC module through the ultrasonic probe. The fuzzy PID control method is used to specify the PLC module's processing of the preload value and the speed of the tightening motor 21 and the control of the tightening motor 21, that is, the conversion between the control layer and the electrical layer is realized through the PLC module; similarly, the rotation of the turntable motor 10 and the slide motor 12 controls the rotation and advance and retreat of the tightening structure 34, that is, the conversion from the electrical layer to the execution layer is realized through the servo motor and the servo driver; wherein the PLC module is powered by a 24V DC power supply. The PLC module needs to be connected to the servo driver, the touch screen, and the ultrasonic preload detection system 36 respectively. The servo driver used in the automatic control system is powered by a 220V power supply, and the communication between the servo driver and the PLC module is realized through the network cable. One end of the servo driver is connected to the PLC module, and the other end is connected to the next servo driver, so as to realize the control of multiple servo drivers by the PLC module. At the same time, the servo driver needs to be connected to the power line of the servo motor and the encoder line built into the servo motor to control the servo motor.

[0072] At the same time, for the motor of the electric slide, if the power is suddenly cut off and the motor is disabled, the slide connection and tightening part may fall vertically and cause danger. Therefore, a servo motor with a brake function needs to be selected. Therefore, for this servo motor, in addition to the conventional connection with the servo driver, its servo motor brake line needs to be connected to the 24V power supply. The PLC module communicates with the ultrasonic test system through the network cable. At the same time, the preload measurement of the ultrasonic preload detection system 36 also requires the oscilloscope to be connected to the PC module 27 through the network cable. Therefore, a switch is used to increase the network cable interface to realize the mutual communication between the oscilloscope and the PC module 27, and the PC module 27 and the PLC module. In order to realize the touch screen used for human-computer interaction, it is necessary to be connected to the PLC module through a network cable. In this way, the preliminary construction of the automatic tightening control system is realized.

[0073] Step 5, tightening preparation stage;

[0074] This tightening system uses 45000 N preload as the target preload final value. Connect the rotor 7 to the base 6 to form a connected structure, and fix it to the center of the device base 3 by bolt connection. Start the turntable motor 10, the turntable rotates, the tightening mechanism moves to the top of the first bolt position, shake the handle 28 to move the tightening mechanism radially to the top of the nut, control the slide motor 12, and move the tightening head downward at a faster speed. Move it to 2 cm above the bolt tail and switch to low speed, so that the tightening sleeve 24 is slowly inserted into the nut, and the sleeve is rotated to cap the nut. At this time, the preload feedback method tightening control program is entered and wait for tightening. Apply ultrasound to the bolt head of the bolt 8 to be tightened to detect the real-time preload during the tightening process.

[0075] Step 6: Tighten and obtain real-time preload force;

[0076] The tightening motor 21 is started, and the bolt begins to be tightened. A subroutine in the tightening control program is responsible for reading the real-time preload force transmitted to the PLC module by the ultrasonic preload force detection system 36 and storing it in the corresponding variable. Another subroutine calculates the preload force error and the error change rate by setting the preload force and the real-time preload force, and performs fuzzy reasoning to obtain the corresponding PID parameters and calculate the required speed at this time. The main program adjusts the motor speed in real time through the speed value calculated in the interrupt subroutine, and finally tightens the bolt to the target preload force to complete the tightening action.

[0077] The tightening sleeve 24 stops rotating, the control slide 13 moves upward, and the control turntable 11 rotates to the next station until all tightening is completed.

[0078] Step 7, tightening end stage;

[0079] Control the slide 13 to move upward, withdraw the rotor, shake the ball screw to make the tightening structure return to the center of the device, and control the turntable 11 to return it to the center. Close the operating system, turn off the power, and withdraw the rotor from the tightening device.

Claims

1. A method for controlling the tightening of an aircraft engine rotor based on bolt preload force feedback, characterized in that: The automated tightening equipment used in the tightening control method for the aircraft engine rotor comprises a main structure (30), a turntable structure (31), a ball guide structure (32), a slide structure (33), a tightening structure (34), a connected part structure (35), and an ultrasonic pre-tightening force detection system (36); The main structure (30) is mainly composed of support legs (2), a device base (3), support columns (4), and a platform plate (9); the four support legs (2) are fixed on the device base (3); the lower end of the support column (4) is fixed in the support legs (2); and the upper end of the support column (4) is fixed with the platform plate (9); The connected component structure (35) is mainly composed of a base bottom plate (5), a base (6) and a rotor (7); the four bases (6) are cylindrical, the lower ends of which are fixed to the base bottom plate (5), and the upper ends of which are connected to the rotor (7); the connected component structure (35) is fixed to the center of the device base (3) through the base bottom plate (5), and realizes the counter-torque of the automated tightening equipment; The turntable structure (31) comprises a turntable motor (10) and a turntable (11), wherein the turntable (11) is connected to the turntable motor (10) to realize rotation of the tightening device; The ball guide rail structure (32) is mainly composed of a ball screw (18), a ball guide rail (19) and a guide rail plate (20). The turntable (11) is connected to the platform plate (9) at the bottom and the guide rail plate (20) at the top. The guide rail plate (20) is provided with two ball guide rails (19) and a ball screw (18). The tightening structure (34) can be fed and retracted by shaking the handle (28). The slide structure (33) is mainly composed of a slide motor (12), a slide (13), a slide back plate (14) and a slide plate (15); a slide base plate (16) is connected to the ball guide rail (19) and the slider of the ball screw (18); the slide base plate (16) is connected to the slide (13) and the slide back plate (14); the top of the slide (13) is connected to the slide motor (12); the slide (13) is also connected to the slide plate (15), so as to realize the lifting movement of the tightening structure (34); The tightening structure (34) is mainly composed of a tightening motor (21), a reducer (22), a transverse gear box (23) and a tightening sleeve (24); the end of the transverse gear box (23) is connected to the tightening sleeve (24); one end of the reducer (22) is connected to the tightening motor (21), and the other end is connected to the mounting plate (17) and the transverse gear box (23); the mounting plate (17) passes through a through hole on the guide plate (20) and is connected to the slide plate (15); The ultrasonic preload force detection system (36) is mainly composed of an ultrasonic probe (25), an oscilloscope (26) and a PC module (27) which are connected in sequence; wherein the PLC module and the PC module (27) communicate with each other via a network cable in a ModbusTCP manner, the PC module (27) and the oscilloscope (26) are connected via a network cable, and the ultrasonic probe (25) is connected to the oscilloscope (26), thereby realizing mutual communication between the oscilloscope (26) and the PC module (27), and between the PC module (27) and the PLC module. When in use, the ultrasonic probe (25) needs to be manually pressed against the bolt head of the bolt (8) to be tightened, and the actual value of the preload force detected by the ultrasonic probe (25) can be transmitted to the PLC module; The automated tightening equipment is also equipped with an automated control operating system, including an HMI touch screen, a PLC module, a servo motor, a servo drive, a 24V DC power supply and cables; wherein the servo motor includes: a turntable motor (10), a slide motor (12) and a tightening motor (21); the HMI touch screen is connected to the PLC module via a network cable to achieve human-computer interaction; the PLC module is powered by a 24V DC power supply; the PLC module is respectively connected to the servo drive, the HMI touch screen and the ultrasonic preload force detection system (36); the servo drive is powered by a 220V power supply, and the communication between the servo drive and the PLC module is achieved through the network cable; one end of the servo drive is connected to the PLC module, and the other end is connected to the next servo drive, so as to achieve the control of multiple servo drives by the PLC module; at the same time, the servo drive is connected to the power line of the servo motor and the encoder line built into the servo motor, so as to achieve the control of the servo motor; The following steps are involved: Step 1: Introduce vector control of the preload ring The tightening motor (21) is a permanent magnet synchronous motor. On the basis of the three-closed-loop vector control of the permanent magnet synchronous motor, a preload loop is introduced, and the preload loop and the position loop are combined into a new preload loop, thereby obtaining a new three-closed-loop vector control method of a preload loop, a speed loop, and a current loop. The bolt (8) to be tightened is installed on the rotor (7). In the new preload loop, an ultrasonic preload test method is used to detect the actual value of the preload force of the bolt (8) to be tightened in real time, and the actual value of the preload force is fed back to the fuzzy PID controller. The controller calculates the required speed of the motor according to the difference between the expected value and the actual value and transmits it to the speed loop, thereby completing the control of the tightening process of the bolt (8) to be tightened. At the same time, the ultrasonic preload force detection system (36) will continue to collect the actual value of the preload force of the bolt (8) to be tightened; Step 2: Establish a tightening angle-preload force model based on the preload force feedback method of the permanent magnet synchronous motor The tightening angle-preload model is specifically expressed as: In the formula, is the tightening angle, is the thread pitch, is the bolt preload, is the bolt stiffness, is the stiffness of the connected component, is the thread stiffness, , and They are thread stiffness, nut stiffness and bolt head stiffness affected by surface roughness; Step 3: Design fuzzy PID controller based on preload force feedback method Based on the three-loop vector control method and the established tightening angle-preload force model, a fuzzy PID controller is designed to control the preload force of the bolt to be tightened (8) by taking the current actual value of the preload force as feedback; The ultrasonic preload force detection system (36) collects the actual preload force value of the bolt (8) to be tightened, compares the actual preload force value with the set final preload force value, and inputs the obtained error and error change rate as input quantities into the fuzzy PID controller. The fuzzy PID controller fuzzifies the error and error change rate, and then obtains the fuzzy control quantity through fuzzy rules. The fuzzy control quantity is then processed through non-fuzzy processing to obtain the actual control quantity, that is, the required speed value. The speed value is input into the speed loop, thereby controlling the tightening of the tightening motor. Step 4: Build the experimental system The automated tightening equipment controls the tightening motor (21), the turntable motor (10) of the turntable (11), and the slide motor (12) at the same time, and the control system needs to communicate with the ultrasonic pre-tightening force detection system (36) so as to input the collected actual value of the pre-tightening force of the bolt (8) to be tightened into the control system; A PLC module is selected as a control system, and the control system is divided into a control layer, an electrical layer and an execution layer; a tightening motor (21), a slide motor (12), a turntable motor (10) and a motion control program written by a user constitute the control layer; a PLC module, an ultrasonic preload force detection system (36), a switch for adding a network cable interface, a servo motor, a servo driver, a 220V power supply and a 24V power supply constitute the electrical layer; a tightening structure (34), a slide structure (33) and a turntable structure (31) constitute the execution layer; a motion control program is written by a user in the control layer to set a final value of the preload force and a motion speed for the turntable motor (10) and the slide motor (12), and the measured actual value of the current preload force is transmitted to the PLC module through the ultrasonic probe (25), and a fuzzy PID control method is used to specify the PLC module's processing of the actual value of the preload force and the speed of the tightening motor (21) and the tightening motor The control of the machine (21) is realized by the PLC module, that is, the conversion between the control layer and the electrical layer is realized; similarly, the rotation of the turntable motor (10) and the slide motor (12) is used to control the rotation and advance and retreat of the tightening structure (34), that is, the conversion from the electrical layer to the execution layer is realized by the servo motor and the servo driver; wherein the PLC module is powered by a 24V DC power supply; the PLC module is respectively connected to the servo driver, the HMI touch screen, and the ultrasonic preload force detection system (36); the servo driver used in the electrical layer is powered by a 220V power supply, and the communication between the servo driver and the PLC module is realized through the network cable; one end of the servo driver is connected to the PLC module, and the other end is connected to the next servo driver, so as to realize the control of multiple servo drivers by the PLC module; at the same time, the servo driver is connected to the power line of the servo motor and the encoder line built into the servo motor, so as to realize the control of the servo motor; Step 5: Tightening preparation stage When tightening the bolts (8) to be tightened of the aero-engine rotor, the rotor (7) is placed in the tightening position of the automated tightening equipment and fixed; after the automated tightening equipment and the rotor (7) are positioned, the automated tightening equipment drives the tightening structure (34) to move and enter the interior of the rotor from the entrance of the rotor (7); then, the motion control program is used to control the tightening sleeve (24) to continue to move horizontally and rotate in space, thereby realizing the capping action of the tightening sleeve (24); then, the ultrasonic probe (25) of the ultrasonic pre-tightening force detection system (36) is pressed against the bolt head of the bolt (8) to be tightened, thereby ensuring real-time measurement of the pre-tightening force; Step 6: Tightening process with preload feedback The tightening structure (34) is started to tighten the bolt (8) to be tightened; the ultrasonic pre-tightening force detection system (36) feeds back the real-time pre-tightening force to the tightening motor (21); after the tightening bolt (8) is tightened to the set pre-tightening force final value, the tightening process of the bolt (8) to be tightened is completed; after the tightening of a bolt (8) to be tightened is completed, the motion control program controls the tightening structure (34) to move upward to ensure that the tightening sleeve (24) is separated from the nut, and the tightening sleeve (24) is moved to the next bolt (8) to be tightened through a rotary motion, and the tightening action is repeated until all the bolts installed on the entire rotor (7) are tightened.

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