A precision tightening device and method for a low-pressure turbine front locking nut

Abstract

This invention relates to a precision tightening device and method for a low-pressure turbine front locking nut, belonging to the field of engine component assembly technology. The device includes a tooling system, an actuating mechanism, a tightening mechanism, and a control system. The tooling system has a stop sleeve that meshes with the spline of the engine fan disc and a tightening sleeve for tightening the nut. The tightening mechanism drives the tightening sleeve via a servo tightening machine. The control system coordinates and controls the alignment and tightening process. Both the stop sleeve and the servo tightening machine are fixed to the same load-bearing base. The rigid connection between the stop sleeve and the engine body forms a counter-torque support, enabling the tightening torque and counter-torque to achieve self-balancing within the load-bearing base. This invention effectively solves the problems of large system sway and difficulty in controlling precision when assembling high-torque nuts in deep cavities and horizontal positions, achieving precise alignment and high-precision, high-stability tightening of the nut, thus improving assembly efficiency and automation level.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engine part assembly, and particularly relates to a low-pressure turbine front locking nut precision tightening device and method. BACKGROUND

[0002] With the continuous development of automatic assembly technology in the aviation industry, more challenging requirements are put forward for the quality and efficiency of the assembly of an aero-engine. In the actual engine assembly process, the tightening and alignment process of the low-pressure turbine front locking nut is the bottleneck of the traditional assembly of the aero-engine, and the automatic assembly technology of the low-pressure turbine front locking nut with high precision and high efficiency has become an urgent technical problem to be solved.

[0003] The thread member at the butt joint of the low-pressure turbine front locking nut adopts a deep well structure, and the well opening size is small, and the length-diameter ratio can reach 5.3. The assembly torque of the front locking nut is relatively large, reaching 2500 N.m-3500 N.m. However, the traditional assembly adopts a sleeve wrench for tightening, and the sleeve wrench needs to be inserted into the deep well during the assembly process. In actual operation, two groups of torque multipliers are used to realize torque transmission and reduction, so as to save labor. However, this method has problems such as too many transmission elements, input torque relying on a crane for balance, and large shaking during the tightening process, and the tightening precision cannot be guaranteed. Therefore, a tightening device capable of realizing reverse torque self-balance is urgently needed to solve the problems of deep cavity, large torque and high-precision nut assembly. SUMMARY

[0004] In order to solve the above problems existing in the prior art, the application provides a low-pressure turbine front locking nut precision tightening device and method. The technical problems to be solved by the application are realized through the following technical scheme: The application provides a low-pressure turbine front locking nut precision tightening device, which comprises a tooling system, a motion execution mechanism and a tightening mechanism. The tooling system comprises a tightening sleeve, a guide sleeve and a stop sleeve, the tightening sleeve is arranged in the guide sleeve, and the inner wall of the tightening sleeve is provided with an inner spline for meshing with the outer spline of the front locking nut; the outer wall of the stop sleeve is provided with an outer spline for meshing with the inner spline of the engine fan disc; the guide sleeve is sleeved on the tightening sleeve and the stop sleeve at both ends; The motion execution mechanism comprises an alignment device, the alignment device is axially movable and rotatably arranged in the tightening sleeve, and is used for guiding the alignment and meshing of the tightening sleeve and the front locking nut; The control system is electrically connected to the action execution mechanism and the tightening mechanism, and is used to control the axial feed and rotation of the alignment device, and to control the output torque and speed of the servo tightening machine; the control system is also equipped with a display unit, which is used to display the alignment image and tightening parameters of the tightening sleeve and the front locking nut in real time. The stop sleeve and the servo tightening machine are both fixedly installed on the load-bearing base. The stop sleeve engages with the internal spline of the engine fan disc through its external spline, providing counter-torque support for the tightening device. The tightening torque applied by the tightening mechanism is transmitted to the front locking nut through the tightening sleeve. The control system then controls the action execution mechanism and the tightening mechanism, and the tightening torque and the counter-torque are balanced on the load-bearing base.

[0005] In one embodiment of the present invention, the tightening sleeve and the guide sleeve are connected by a clearance sliding fit, and a positioning pin is provided to limit the axial and angular position of the tightening sleeve relative to the guide sleeve. The positioning pin is used to transmit torque between the tightening sleeve and the guide sleeve.

[0006] In one embodiment of the present invention, the guide sleeve and the stop sleeve are slidably connected, and the clearance between them is no greater than 0.015 mm.

[0007] In one embodiment of the present invention, the alignment device includes an alignment guide shaft and an alignment rotating shaft arranged coaxially; the alignment guide shaft is mounted in the guide sleeve through linear bearings at both ends thereon, and the alignment rotating shaft is mounted in the alignment guide shaft through a bearing assembly.

[0008] In one embodiment of the present invention, the action execution mechanism further includes: a rotary drive unit and an axial feed drive unit; The rotary drive unit includes a rotary servo motor and a rotary gear pair. The driven gear in the rotary gear pair is fixedly mounted on the orthogonal rotary shaft. The rotary servo motor drives the rotary gear pair to rotate, thereby driving the orthogonal rotary shaft to rotate. The axial feed drive unit includes a feed servo motor, a feed gear pair, and a lead screw nut; one end of the alignment guide shaft is provided with a lead screw thread, the lead screw nut is engaged with the lead screw thread, and is connected to the feed slave gear through a keyway; the feed servo motor rotates to drive the feed gear pair, which in turn drives the lead screw nut to rotate, thereby driving the alignment guide shaft to move along its axial direction.

[0009] In one embodiment of the present invention, the stop sleeve is fixedly installed on the load-bearing base by screws.

[0010] In one embodiment of the present invention, the torque transmission gear pair is connected between the output end of the servo tightening machine and the drive end of the tightening sleeve, for amplifying the output torque of the servo tightening machine and transmitting it to the tightening sleeve.

[0011] In one embodiment of the present invention, the tightening device is integrally mounted on a guide rail and extends into or out of the engine assembly blind cavity through the guide rail.

[0012] In one embodiment of the present invention, the control system further includes an industrial computer, which is used to control the tightening process of the servo tightening machine according to a preset tightening program, and to collect the tightening torque and angle curves in real time.

[0013] The present invention also provides a digital method for precision tightening of the front locking nut of a low-pressure turbine, using the above-mentioned tightening device, including: Step 1: extending the entire tightening device forward along the guide rail and into the engine assembly blind cavity; Step 2: During the forward movement of the tightening device or after it reaches the predetermined position, rotate the engine fan disc to make the external spline of the stop sleeve engage with the internal spline of the engine fan disc, thus establishing a reverse torque transmission path. Step 3: Drive the alignment device through the action actuator to perform the alignment operation, and use the display unit of the control system for visual guidance to align and engage the tightening sleeve with the front locking nut of the low-pressure turbine; Step 4: With the anti-torque support provided by the stop sleeve, the tightening mechanism is started through the control system, and the servo tightening machine is controlled to drive the tightening sleeve to rotate, tightening the low-pressure turbine front locking nut, and the tightening torque and angle are monitored and recorded in real time. Step 5: After tightening, remove the alignment device and the tightening device in sequence.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The low-pressure turbine front locking nut precision tightening device of the present invention constructs an internal anti-torque self-balancing system by setting a stop sleeve that rigidly engages with the engine fan disc and fixing it together with the servo tightening machine that drives the tightening sleeve on the same load-bearing base. This system transmits the reaction torque generated during tightening through the engine body structure and cancels it out internally, thereby eliminating dependence on unstable external supports. It provides a rigid foundation for the device and effectively solves the problem of precision loss due to system sway during high-torque tightening in deep cavities and horizontal positions.

[0015] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a precision tightening device for a low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 2 This is a structural cross-sectional view of the precision tightening device for the low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 3 This is a structural cross-sectional view of the action execution mechanism provided in an embodiment of the present invention; Figure 4 This is an exploded structural diagram of the action execution mechanism provided in an embodiment of the present invention; Figure 5 This is a partial structural schematic diagram of the action execution mechanism provided in an embodiment of the present invention; Figure 6 This is a simplified kinematic model diagram of the precision tightening device for the low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 7 This is a simplified stress model diagram of the load-bearing base provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the front locking nut provided in an embodiment of the present invention; Figure 9 This is a flowchart illustrating the operation of the precision tightening device for the low-pressure turbine front locking nut provided in this embodiment of the invention.

[0017] Reference numerals: 1-Tooling system; 11-Tightening sleeve; 12-Guide sleeve; 13-Stop sleeve; 2-Actuation mechanism; 21-Alignment rotation shaft; 22-Alignment guide shaft; 23-Linear bearing; 24-Bearing assembly; 25-Rotary drive unit; 251-Rotary servo motor; 252-Rotary gear pair; 26-Axial feed drive unit; 261-Feed servo motor; 262-Feed gear pair; 263-Screw nut; 3-Tightening mechanism; 31-Servo tightening machine; 32-Torque transmission gear pair; 4-Bearing base. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of a precision tightening device for a low-pressure turbine front locking nut, in conjunction with the accompanying drawings and specific embodiments, is provided.

[0019] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0020] Example 1 like Figures 1 to 8 As shown, Figure 1 This is a schematic diagram of the structure of a precision tightening device for a low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 2 This is a structural cross-sectional view of the precision tightening device for the low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 3 This is a structural cross-sectional view of the action execution mechanism provided in an embodiment of the present invention; Figure 4 This is an exploded structural diagram of the action execution mechanism provided in an embodiment of the present invention; Figure 5 This is a partial structural schematic diagram of the action execution mechanism provided in an embodiment of the present invention; Figure 6 This is a simplified kinematic model diagram of the precision tightening device for the low-pressure turbine front locking nut provided in an embodiment of the present invention; Figure 7 This is a simplified stress model diagram of the load-bearing base provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the front locking nut provided in an embodiment of the present invention.

[0021] This embodiment provides a precision tightening device for the front locking nut of a low-pressure turbine. The entire tightening device is mounted on an automated axial alignment guide rail via a load-bearing base 4, and can extend into or out of the engine's assembly blind cavity along the guide rail. The guide rail ensures precise guidance of the device within the deep cavity. The tightening device includes a tooling system 1, an actuating mechanism 2, a tightening mechanism 3, a control system, and a load-bearing base 4.

[0022] In this embodiment, the tooling system 1 includes a tightening sleeve 11, a guide sleeve 12, and a stop sleeve 13. The tightening sleeve 11 is cylindrical, with an internal spline on its inner wall for engaging with the external spline of the front locking nut. The tightening sleeve 11 is located inside the guide sleeve 12, and the two are connected by a sliding fit with a clearance. A locating pin restricts the axial and angular position of the tightening sleeve 11 relative to the guide sleeve 12, and transmits torque between the tightening sleeve 11 and the guide sleeve 12. The two ends of the guide sleeve 12 are respectively fitted inside the tightening sleeve 11 and the stop sleeve 13. The guide sleeve 12 and the stop sleeve 13 are slidably connected, with a clearance of no more than 0.015 mm to ensure flexible rotation of the guide sleeve 12. The stop sleeve 13 is fixedly mounted on the load-bearing base 4 by screws, and its outer wall has an external spline for engaging with the internal spline of the engine fan disc.

[0023] In this embodiment, the action execution mechanism 2 includes an alignment device, which is axially movable and rotatably inserted into the tightening sleeve 11 to guide the tightening sleeve 11 to align and engage with the front locking nut. The alignment device includes an alignment rotating shaft 21 and an alignment guide shaft 22 arranged coaxially. The alignment guide shaft 22 is installed in the guide sleeve 12 through linear bearings 23 at both ends and can move and rotate freely along the axial direction of the guide sleeve 12. The alignment rotating shaft 21 is installed in the alignment guide shaft 22 through two bearing assemblies 24 and can rotate freely along the axial direction of the alignment guide shaft 22.

[0024] Specifically, the actuator 2 controls the axial feed and rotation of the alignment device, and includes a rotary drive unit 25 and an axial feed drive unit 26. The rotary drive unit 25 includes a rotary servo motor 251 and a rotary gear pair 252, wherein the rotary gear pair 252 includes a main rotary gear and a driven rotary gear. The driven rotary gear of the rotary gear pair 252 is fixedly mounted on the alignment rotation shaft 21, and the angular direction is limited by a keyway connection, so that the alignment rotation shaft 21 rotates synchronously with the driven gear. The servo motor of the rotary drive unit drives the main rotary gear of the rotary gear pair 252, thereby driving the rotary gear pair 252 to rotate through the rotary servo motor 251, thereby driving the alignment rotation shaft 21 to rotate. Furthermore, the axial feed drive unit 26 includes a feed servo motor 261, a feed gear pair 262, and a lead screw nut 263. One end of the alignment guide shaft 22 is provided with a lead screw thread, and the lead screw nut 263 is engaged with the lead screw thread at the end of the alignment guide shaft 22 and is connected to the feed driven gear through a keyway. The feed gear pair 262 includes a feed master gear and a feed slave gear. The feed servo motor 261 rotates to drive the feed gear pair 262, which in turn drives the lead screw nut 263 to rotate, thereby driving the alignment guide shaft 22 to move axially.

[0025] In this embodiment, the tightening mechanism 3 includes a servo tightening machine 31 and a torque transmission gear pair 32. The servo tightening machine 31 is fixedly installed on the load-bearing base 4, and its output end is connected to the drive end of the tightening sleeve 11 through the torque transmission gear pair 32. The torque transmission gear pair 32 is used to amplify the output torque of the servo tightening machine 31 and transmit it to the tightening sleeve 11 to meet the tightening and torque distribution requirements of the low-pressure turbine front locking nut.

[0026] In this embodiment, the precision tightening device for the low-pressure turbine front locking nut of the present invention is further equipped with a control system, which includes an industrial computer, a display screen, and a control unit. The control system is electrically connected to the action execution mechanism 2 and the tightening mechanism 3, and is used to control the axial feed and rotation of the alignment device, and to control the output torque and speed of the servo tightening machine 31. The display screen serves as a display unit, outputting in real time the alignment image of the tightening sleeve 11 and the front locking nut, the alignment status of the nut locking groove and the low-pressure turbine locking groove, and simultaneously displaying key data such as the current tightening torque and tightening rotation angle. Specifically, the industrial computer can control the tightening process of the servo tightening machine 31 according to a preset tightening program, and collect the tightening torque and angle curves in real time, realizing comprehensive monitoring of the nut status during the tightening process. Through parameter adjustment, torque monitoring, torque verification, tightening curve optimization, and other methods, the precision tightening assembly of the low-pressure turbine front locking nut is satisfied.

[0027] It is worth noting that both the retaining sleeve 13 and the servo tightening machine 31 are fixedly mounted on the same load-bearing base 4. The retaining sleeve 13 forms a rigid connection by engaging its external spline with the internal spline of the engine fan disc, providing counter-torque support for the tightening device. When the servo tightening machine 31 drives the tightening sleeve 11 to rotate clockwise to tighten the front locking nut, the counter-torque applied by the front locking nut to the tightening sleeve 11 is in the counter-clockwise direction. This counter-torque is transmitted to the servo tightening machine 31 through the torque transmission gear pair 32, and then to the load-bearing base 4. At the same time, the front locking nut transmits torque to the low-pressure turbine shaft through its threads. The low-pressure turbine shaft then transmits the torque forward to the fan shaft. The fan shaft transmits the torque to the external spline of the retaining sleeve 13 through its internal spline, and then to the load-bearing base 4. The load-bearing base 4 simultaneously bears the counterclockwise torque from the servo tightening machine 31 and the clockwise torque from the stop sleeve 13. The two torques cancel each other out inside the load-bearing base 4, thus achieving self-balancing of the counterclockwise torque. This structure eliminates the dependence on unstable external supports, provides a rigid foundation for the tightening process, and effectively solves the problems of swaying and loss of precision control during high-torque tightening in deep cavities and horizontal positions.

[0028] Furthermore, the alignment process can be achieved through the display unit of the control system using visual recognition assistance. Optionally, the display unit includes an image acquisition component and a display screen. The image acquisition component is used to acquire images of the alignment status and locking groove positions of the tightening sleeve and the front locking nut. The display screen is used to display the images acquired by the image acquisition component in real time to achieve visual recognition and guidance. After visually recognizing the groove positions of the turbine shaft and the front locking nut, the actuation mechanism 2 controls the axial feed and rotation to make the groove positions of the two fit together; then, driven by the tightening mechanism, the alignment of the two locking grooves is achieved.

[0029] The low-pressure turbine front locking nut precision tightening device of the present invention constructs an internal anti-torque self-balancing system by setting a stop sleeve that rigidly engages with the engine fan disc and fixing it together with the servo tightening machine that drives the tightening sleeve on the same load-bearing base. This system transmits the reaction torque generated during tightening through the engine body structure and cancels it out internally, thereby eliminating dependence on unstable external supports. It provides a rigid foundation for the device and effectively solves the problem of precision loss due to system sway during high-torque tightening in deep cavities and horizontal positions.

[0030] Example 2 like Figure 9 As shown, Figure 9 This is a flowchart illustrating the operation of the precision tightening device for the low-pressure turbine front locking nut provided in this embodiment of the invention.

[0031] This embodiment provides a digital method for precisely tightening the front locking nut of a low-pressure turbine, including: Step 1: Extend the entire tightening device forward along the guide rail and insert it into the engine assembly blind cavity; Step 2: During the tightening process or after reaching the predetermined position, rotate the engine fan disc to make the external spline of the stop sleeve engage with the internal spline of the engine fan disc, thus establishing a reverse torque transmission path. Step 3: Drive the alignment device through the action actuator to perform the alignment operation, and use the display unit of the control system for visual guidance to align and engage the tightening sleeve with the front locking nut of the low-pressure turbine.

[0032] Specifically, the alignment device is driven by the action actuator to perform the alignment operation, and at the same time, the tightening mechanism is driven to tighten the low-pressure front locking nut. Then, by identifying the slot alignment status in real time, the slot of the low-pressure turbine front locking nut is aligned with the slot of the low-pressure turbine shaft.

[0033] Step 4: With the anti-torque support provided by the stop sleeve, the tightening mechanism is started through the control system, and the servo tightening machine is controlled to drive the tightening sleeve to rotate, tightening the low-pressure turbine front locking nut, and the tightening torque and angle are monitored and recorded in real time. Step 5: After tightening, remove the alignment device and tightening device in sequence.

[0034] To enable those skilled in the art to fully understand and implement this invention, the specific implementation principle of this invention will be further explained below in conjunction with a specific application scenario.

[0035] First, mount the entire tightening device onto the automated axial alignment guide rail, adjust the position of the guide rail, and extend the entire device forward along the guide rail so that the tightening sleeve, guide sleeve and other components extend into the engine assembly blind cavity.

[0036] During the tightening process or after reaching the predetermined position, rotate the engine fan disc to engage the external spline of the stop sleeve with the internal spline of the engine fan disc, thus establishing a reverse torque transmission path.

[0037] The alignment device is then driven by the action actuator to perform the alignment operation: First, the control system drives the rotary drive unit to rotate the alignment rotation shaft, and at the same time, the axial feed drive unit moves the alignment guide shaft axially to adjust the position of the front end of the alignment device; the control system's image acquisition component and display screen provide visual guidance to observe the relative position of the tightening sleeve and the front locking nut, so that the inner spline of the tightening sleeve and the outer spline of the front locking nut are aligned and slowly engaged.

[0038] With the stop sleeve providing counter-torque support, the tightening mechanism is activated by the control system. The servo tightening machine outputs torque and speed according to a preset program, and the tightening sleeve is driven to rotate through the torque transmission gear pair 32 to tighten the locking nut in front of the low-pressure turbine. During the tightening process, the control system monitors and records the tightening torque and angle curve in real time to ensure that the tightening torque is controlled within the range of 2500 Nm to 3500 Nm, and automatically stops after the target torque is reached.

[0039] After tightening, the alignment device is first disengaged via the actuation mechanism 2, and then the entire tightening device is withdrawn from the assembly blind cavity along the guide rail. Furthermore, higher precision assembly can be achieved subsequently through stress relief.

[0040] It should be noted that the alignment method provided in Embodiment 2 of the present invention can be implemented using the alignment device provided in Embodiment 1, and therefore has similar beneficial effects to the device embodiment in Embodiment 1. For technical details not disclosed in the method embodiments of the present invention, please refer to the description of the device embodiments for understanding.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0042] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A precision tightening device for a low-pressure turbine front locking nut, characterized in that, include: The tooling system includes a tightening sleeve, a guide sleeve, and a stop sleeve. The tightening sleeve is disposed inside the guide sleeve, and the inner wall of the tightening sleeve is provided with an internal spline for engaging with the external spline of the front locking nut. The outer wall of the stop sleeve is provided with an external spline for engaging with the internal spline of the engine fan disc. The two ends of the guide sleeve are respectively fitted inside the tightening sleeve and the stop sleeve. The action actuator includes an alignment device, which is axially movable and rotatably inserted into the tightening sleeve, for guiding the tightening sleeve to align and engage with the front locking nut; The tightening mechanism includes a servo tightening machine and a torque transmission gear pair, wherein the servo tightening machine drives the tightening sleeve to rotate through the torque transmission gear pair; The control system is electrically connected to the action execution mechanism and the tightening mechanism, and is used to control the axial feed and rotation of the alignment device, and to control the output torque and speed of the servo tightening machine; the control system is also equipped with a display unit, which is used to display the alignment image and tightening parameters of the tightening sleeve and the front locking nut in real time. The stop sleeve and the servo tightening machine are both fixedly installed on the load-bearing base. The stop sleeve engages with the internal spline of the engine fan disc through its external spline, providing counter-torque support for the tightening device. The tightening torque applied by the tightening mechanism is transmitted to the front locking nut through the tightening sleeve. The control system then controls the action execution mechanism and the tightening mechanism, and the tightening torque and the counter-torque are balanced on the load-bearing base.

2. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The tightening sleeve and the guide sleeve are connected by a clearance sliding fit, and a positioning pin is provided to limit the axial and angular position of the tightening sleeve relative to the guide sleeve. The positioning pin is used to transmit torque between the tightening sleeve and the guide sleeve.

3. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The guide sleeve and the stop sleeve are connected by a sliding fit, and the clearance between them is no greater than 0.015mm.

4. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The alignment device includes an alignment guide shaft and an alignment rotating shaft arranged coaxially; the alignment guide shaft is installed in the guide sleeve through linear bearings at both ends, and the alignment rotating shaft is installed in the alignment guide shaft through a bearing assembly.

5. The precision tightening device for the low-pressure turbine front locking nut according to claim 4, characterized in that, The motion execution mechanism further includes: a rotary drive unit and an axial feed drive unit; The rotary drive unit includes a rotary servo motor and a rotary gear pair. The driven gear in the rotary gear pair is fixedly mounted on the orthogonal rotary shaft. The rotary servo motor drives the rotary gear pair to rotate, thereby driving the orthogonal rotary shaft to rotate. The axial feed drive unit includes a feed servo motor, a feed gear pair, and a lead screw nut; one end of the alignment guide shaft is provided with a lead screw thread, the lead screw nut is engaged with the lead screw thread, and is connected to the feed slave gear through a keyway; the feed servo motor rotates to drive the feed gear pair, which in turn drives the lead screw nut to rotate, thereby driving the alignment guide shaft to move along its axial direction.

6. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The stop sleeve is fixedly installed on the load-bearing base by screws.

7. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The torque transmission gear pair is connected between the output end of the servo tightening machine and the drive end of the tightening sleeve, and is used to amplify the output torque of the servo tightening machine and transmit it to the tightening sleeve.

8. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The tightening device is mounted on the guide rail and extends into or out of the engine assembly blind cavity through the guide rail.

9. The precision tightening device for the low-pressure turbine front locking nut according to claim 1, characterized in that, The control system also includes an industrial computer, which is used to control the tightening process of the servo tightening machine according to a preset tightening program, and to collect the tightening torque and angle curves in real time.

10. A digital method for precisely tightening a low-pressure turbine front locking nut, characterized in that, The tightening device according to any one of claims 1 to 9 comprises: Step 1: Extend the entire tightening device forward along the guide rail and insert it into the engine assembly blind cavity; Step 2: During the forward movement of the tightening device or after it reaches the predetermined position, rotate the engine fan disc to make the external spline of the stop sleeve engage with the internal spline of the engine fan disc, thus establishing a reverse torque transmission path. Step 3: Drive the alignment device through the action actuator to perform the alignment operation, and use the display unit of the control system for visual guidance to align and engage the tightening sleeve with the front locking nut of the low-pressure turbine; Step 4: With the anti-torque support provided by the stop sleeve, the tightening mechanism is started through the control system, and the servo tightening machine is controlled to drive the tightening sleeve to rotate, tightening the low-pressure turbine front locking nut, and the tightening torque and angle are monitored and recorded in real time. Step 5: After tightening, remove the alignment device and the tightening device in sequence.

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