A stress-free clamping method and system for aero-engine precision thin-walled parts

Abstract

The application provides a stress-free clamping method and system for an aero-engine precision thin-wall part, and relates to the technical field of aero-engine part manufacturing. The method comprises the following steps: precisely grinding the upper end face of the jig base blank to form a finished positioning surface; taking the finished positioning surface as a reference, machining a plurality of uniformly distributed precision mounting holes on the circumference of the distribution circle of the part mounting hole to obtain a high-precision jig base; based on the high-precision jig base, installing an inner diameter expansion pin in each precision mounting hole, and making the axis of each inner diameter expansion pin perpendicular to the positioning surface of the base; and attaching the part to be machined to the positioning surface of the base with the design reference surface to obtain initial positioning. The application constrains the clamping force to the local area of the mounting hole through reference construction, precise positioning, measurement compensation and force flow path optimization, and realizes the stress-free clamping state of the thin-wall area of the part.

Description

Technical Field

[0001] This invention relates to the field of aero-engine component manufacturing technology, and in particular to a stress-free clamping method and system for precision thin-walled aero-engine components. Background Technology

[0002] In the field of high-end equipment manufacturing such as aero-engines, there are a large number of thin-walled, weakly rigid, and high-precision parts. When these parts are finally finished, traditional clamping methods such as end face clamping, inner hole expansion, and outer circle clamping have inherent defects: the clamping force acts directly or indirectly on the key positioning reference or weak body of the part, resulting in clamping deformation, which may make it difficult to meet the form and position tolerance requirements.

[0003] With the development of intelligent manufacturing and digital measurement technologies, some existing technologies attempt to introduce online measurement and data processing methods during clamping to improve clamping accuracy. However, existing solutions have the following shortcomings at the data processing level: Existing methods rely solely on manual or simple measurements to obtain part position information, failing to establish a deviation distribution model between the initial and designed shapes of the part in its current clamping state. This can lead to a lack of accurate data foundation for subsequent clamping force compensation. Current technologies often use empirical formulas or uniform distribution methods to set the driving force at each clamping point, without conducting finite element numerical simulations of the elastic deformation characteristics of thin-walled parts. This makes it impossible to quantitatively predict the elastic deformation distribution under clamping force, potentially leading to significant arbitrariness in the calculation of compensation adjustment values. Applying clamping force directly after part positioning, without prior feature point measurement, surface fitting, mesh generation, and finite element simulation to form a closed-loop data processing system of measurement, modeling, simulation, and compensation, may struggle to offset elastic deformation offsets caused by initial shape and position errors and the part's own weight. Due to the lack of precise calculation of deformation prediction values ​​for each clamping point, existing technologies typically apply the same driving torque to all clamping units, failing to differentiate compensation based on the actual deformation trends at each mounting hole. This can result in localized over-tightening or over-loosening, affecting clamping uniformity and machining accuracy. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a stress-free clamping method and system for precision thin-walled parts of aero-engines. By constructing a reference, precise positioning, measurement compensation and force flow path optimization, the clamping force is constrained to a local area of ​​the mounting hole, thereby achieving a stress-free clamping state in the thin-walled area of ​​the part.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, a stress-free clamping method for precision thin-walled components of an aero-engine is provided, the method comprising: The upper end face of the fixture base blank is precision ground to form a precision positioning surface; using the precision positioning surface as a reference, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Based on a high-precision fixture base, an inner diameter expansion pin is installed in each precision mounting hole, and the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base. The part to be processed is placed against the positioning surface of the base with its design reference surface to obtain initial positioning; Based on the initial positioning, each inner diameter expansion pin passes through the corresponding connecting hole on the mounting edge of the part to establish a preliminary connection; based on the preliminary connection, preset feature points on the part are selected for measurement to obtain their spatial coordinate data and fit to obtain a virtual reference surface; after meshing the virtual reference surface, finite element numerical simulation is carried out to obtain the deformation prediction value; based on the deformation prediction value, the compensation adjustment value is calculated. Based on the compensation adjustment value, the driving torque of each inner diameter expansion pin is set; a tightening force is applied to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. Based on radial elastic expansion, the elastic sleeve forms an interference fit with the wall of the mounting hole of the part, and the clamping force is transmitted to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

[0006] Secondly, a stress-free clamping system for precision thin-walled components of an aero-engine includes: The tooling preparation module is used to precision grind the upper end face of the fixture base blank to form a precision-machined positioning surface. Based on the precision-machined positioning surface, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Based on the high-precision fixture base, an inner diameter expansion pin is installed in each precision mounting hole, and the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base. The positioning module is used to align the part to be processed with its designed reference surface against the positioning surface of the base to obtain initial positioning; The measurement and compensation module is used to establish a preliminary connection by having each inner diameter expansion pin pass through the corresponding connection hole on the mounting edge of the part based on the initial positioning; based on the preliminary connection, it selects preset feature points on the part for measurement, obtains their spatial coordinate data, and fits them to obtain a virtual reference surface; after meshing the virtual reference surface, it performs finite element numerical simulation to obtain the deformation prediction value; and calculates the compensation adjustment value based on the deformation prediction value. The clamping actuator module is used to set the driving torque of each inner diameter expansion pin according to the compensation adjustment value; and to apply a tightening force to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. The implementation module is used to form an interference fit between the elastic sleeve and the wall of the mounting hole of the part based on radial elastic expansion, and to transmit the clamping force to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

[0007] Thirdly, a computing device, comprising: One or more processors; A storage device for storing one or more programs that, when executed by one or more processors, cause the one or more processors to implement the method.

[0008] Fourthly, a computer-readable storage medium storing a program that, when executed by a processor, implements the method.

[0009] The above-described solution of the present invention has at least the following beneficial effects: Precision grinding creates a regular, finely machined locating surface, ensuring the consistency of the datum for subsequent machining and clamping. Precision mounting holes are machined to a datum position, improving the overall accuracy of the fixture base and laying a solid hardware foundation for subsequent clamping operations. Inner diameter expansion pins are fitted into the precision mounting holes of the high-precision fixture base, ensuring that each expansion pin is correctly positioned and its axis is perpendicular to the standard. This standardizes the layout of the clamping actuators and simplifies subsequent clamping operations. Initial positioning is achieved by aligning the part's design datum surface with the base's locating surface, conforming to the datum design requirements, ensuring the part's initial placement posture is compliant, reducing positioning deviations, and improving initial clamping accuracy. After the initial connection between the part and the inner diameter expansion pins is completed, spatial coordinate data is collected through feature point measurement. A virtual datum surface is constructed based on data fitting to realize the part's morphology. The digital restoration is performed; meshing and finite element numerical simulation are carried out on the virtual reference surface to quantitatively analyze the deformation trend of the part and obtain the deformation prediction value. Based on the prediction value, the compensation adjustment value is calculated to form a complete data processing link of measurement, modeling, simulation and compensation, which provides reliable data support for subsequent clamping control; the driving torque of each inner diameter expansion pin is set differently according to the compensation adjustment value to achieve precise matching and control of clamping force. The tightening force is applied according to the torque to drive the sleeve to expand evenly, ensuring balanced clamping force and avoiding abnormal local force; the uniform expansion of the elastic sleeve forms an interference fit, constructs a closed-loop force flow path, and transmits the clamping force to the fixture base in a directional manner to achieve local constraint of clamping force, isolate the force interference in the thin-walled area, achieve stress-free clamping of the thin-walled area of ​​the part, and ensure the form and position accuracy of subsequent finishing. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating a stress-free clamping method for precision thin-walled components of an aero-engine, provided by an embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram of a stress-free clamping system for precision thin-walled components of an aero-engine, provided by an embodiment of the present invention. Detailed Implementation

[0012] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0013] like Figure 1 As shown, an embodiment of the present invention proposes a stress-free clamping method for precision thin-walled components of an aero-engine, the method comprising the following steps: Step 100: Precision grinding is performed on the upper end face of the fixture base blank to form a precision positioning surface; using the precision positioning surface as a reference, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Step 200: Based on the high-precision fixture base, install an inner diameter expansion pin in each precision mounting hole, and make the axis of each inner diameter expansion pin perpendicular to the positioning surface of the base. Step 300: Place the part to be processed against the positioning surface of the base with its design reference surface to obtain initial positioning; Step 400: Based on the initial positioning, each inner diameter expansion pin passes through the corresponding connecting hole on the mounting edge of the part to establish a preliminary connection; based on the preliminary connection, preset feature points on the part are selected for measurement to obtain their spatial coordinate data and fit to obtain a virtual reference surface; after meshing the virtual reference surface, finite element numerical simulation is carried out to obtain the deformation prediction value; based on the deformation prediction value, the compensation adjustment value is calculated. Step 500: Based on the compensation adjustment value, set the driving torque for each inner diameter expansion pin; apply a tightening force to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. Step 600: Based on radial elastic expansion, the elastic sleeve forms an interference fit with the wall of the part mounting hole, and the clamping force is transmitted to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

[0014] In this embodiment of the invention, a stable and reliable precision-machined positioning surface is formed by precision grinding. Precision mounting holes are machined evenly distributed using this positioning surface as a reference, ensuring the form and position accuracy of the fixture base is consistent with the mounting reference, providing a stable foundation for subsequent clamping. The axis of the inner diameter expansion pin is ensured to be perpendicular to the positioning surface, making the clamping force transmission direction regular and uniform, avoiding lateral stress during clamping. The part's own design reference surface is used for fitting and positioning, ensuring accurate initial positioning that meets design and machining requirements. The coordinates of feature points are measured and a virtual reference surface is fitted, providing accurate data reference for the clamping state. Mesh generation and finite element numerical simulation can quantitatively analyze the deformation trend of the part, calculate compensation adjustment values, and achieve deformation prediction and parameter optimization based on data processing. Differential drive torques are set according to the compensation adjustment values ​​to precisely control the expansion force of each expansion pin, ensuring the clamping force matches the force characteristics of the part. An elastic sleeve is interference-fitted with the hole wall and transmits the clamping force to the fixture base, avoiding stress on thin-walled areas, maintaining a stress-free clamping state for the part, and ensuring machining accuracy.

[0015] In a preferred embodiment of the present invention, step 100 involves precision grinding the upper end face of the fixture base blank to form a precision-machined positioning surface; using the precision-machined positioning surface as a reference, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base, comprising: Step 101: Provide a fixture base blank and perform rough machining on its shape to form a preliminary base outline. Specifically, this includes: considering the finished fixture base's disc-shaped structure parameters of 550mm outer diameter and 80mm total height, as well as the layout requirements of four evenly distributed countersunk mounting holes on the bottom of the base and 12 precision mounting holes for expansion pins on a 416mm diameter circumference, calculating and determining the pre-cutting allowance in each direction for the outer circumferential end face and upper and lower end faces of the base based on the difference between the original dimensions of the blank and the final dimensions of the finished product; dividing the rough-machined shafts according to the overall rigidity requirements of the disc-shaped structure. For both the axial and circumferential cutting levels, the cutting depth, feed rate, and spindle speed parameters corresponding to each cutting level are calculated and determined according to the general process specifications for precision machining. Through dimensional transfer relationships and tolerance allocation, the intermediate dimensional control range of various external surfaces such as the outer diameter, total height, and bottom mounting plane of the base is determined after rough machining. This completes the calculation of process parameters and the planning of machining procedures for the entire rough machining process, ultimately forming a preliminary base outline with regular dimensions, stable structure, and adaptability to subsequent precision grinding and precision machining of holes.

[0016] Step 102: Based on the preliminary base outline, the upper surface of the blank is precision ground to form a precision-machined positioning surface with high flatness requirements. Specifically, this includes: uniformly selecting multiple detection points along the circumferential and radial directions on the upper surface of the preliminary base outline; using a precision measuring device, sequentially collecting height data of each detection point relative to a fixed measurement reference; importing all height data of the detection points into the data processing unit; and using a least-squares plane fitting algorithm to perform unified calculations on all height data. The least-squares plane fitting algorithm performs overall optimal fitting calculations on spatially distributed multi-point measured data. By balancing the distance deviations between each point and the fitting plane, a reference plane with the smallest overall deviation value from all detection points is obtained. The surface serves as the core basis for evaluating the flatness and parallelism of the upper end face. Based on the height difference between the reference plane generated by fitting and each detection point on the actual end face, the amount of material removed in different areas of the upper end face is calculated. According to the distribution of material removal in each area, combined with the characteristics of precision grinding, the total number of grinding operations and the feed rate of a single grinding operation are determined. After each grinding operation, the end face detection point data is re-collected, and the least squares plane fitting calculation and deviation analysis calculation are repeatedly performed. Based on the calculation results, the grinding path and grinding parameters are iteratively corrected to continuously reduce the deviation values ​​between each area of ​​the end face and the reference plane until the overall flatness and parallelism of the upper end face meet the design requirements, and finally a precision-machined positioning surface that can be used for precise positioning of parts is formed.

[0017] Step 103: Using the precision-machined positioning surface as a reference, drill multiple evenly distributed precision mounting holes on the circumference of the corresponding part mounting hole distribution circle. During the machining process, control the position and diameter tolerance of each hole in real time to obtain the finished precision mounting holes. Specifically, this includes: using the precision-machined positioning surface as the machining reference, determining the distribution center and radius of the hole system based on the diameter of the part mounting hole distribution circle (416mm) and the evenly distributed number of 12 mounting holes, and using the central axis of the fixture base as the rotation center; selecting the symmetrical center line of the countersunk mounting hole on the base used for machine tool fixation as the preset reference axis. The preset reference axis is a reference axis used to calibrate the starting angle and orientation of the hole system. This preset reference axis passes through the center of the base and coincides with the symmetrical center line of the base shape, thereby achieving the relative positional unity of the hole system and the overall structure of the base. The polar coordinate transformation algorithm is used to calculate and transform the hole position parameters. The polar coordinate transformation algorithm converts the hole position parameters on the distribution circle from polar coordinate form to rectangular coordinate form for easy recognition and execution by the CNC machining system.

[0018] Using the center of the base as the pole and the preset reference axis as the polar axis, the polar diameter and polar angle parameters corresponding to each of the 12 precision mounting holes are calculated. Through a polar coordinate transformation algorithm, the above polar diameter and polar angle parameters are converted into rectangular coordinate parameters required for CNC machining, thus obtaining the theoretical center coordinates of each precision mounting hole. At the same time, the equal circumferential angle between adjacent mounting holes is calculated. Based on the positional tolerance and diameter tolerance requirements of the mounting holes, the allowable fluctuation range of the theoretical coordinates and the diameter is determined. During the drilling process, the actual center coordinates and diameter data of each hole are collected in real time. The difference between the actual data and the theoretical data is calculated, and the spatial position and feed parameters of the drilling tool are adjusted in real time according to the calculation results to ensure that the diameter and positional tolerance of each precision mounting hole are continuously controlled, thus completing the calculation and dynamic control of the entire hole system machining process.

[0019] Step 104: Perform positional and perpendicularity tests on each precision mounting hole to confirm that its perpendicularity relative to the precision-machined positioning surface and its positional accuracy with respect to each other meet the design requirements, thereby obtaining a high-precision fixture base with precision mounting holes. Specifically, this includes: using the precision-machined positioning surface as the reference plane for precision testing; acquiring the axial spatial attitude of each of the 12 precision mounting holes using precision testing equipment to obtain the spatial coordinate data of the hole opening and bottom for each mounting hole; calculating the perpendicularity deviation of the axis of each mounting hole relative to the precision-machined positioning surface based on the reference plane and the spatial coordinate data of each mounting hole; and calculating the perpendicularity deviation of the hole axis relative to the precision-machined positioning surface based on the hole system distribution. Using the theoretical center as a reference, and based on the evenly distributed arrangement of 12 holes, the actual center distance deviation and angular deviation between adjacent mounting holes, as well as the total positional deviation of the entire hole system relative to the theoretical distribution circle, are calculated. The calculated verticality deviation of a single hole, the relative positional deviation between holes, and the total positional deviation of the entire hole system are compared with the accuracy limits given in the design. Through deviation compliance verification calculations, it is confirmed that the verticality and positional accuracy of all mounting holes, as well as the overall accuracy of the hole system, meet the requirements for the installation of the inner diameter expansion pin and the requirements for stress-free clamping. After complete accuracy verification calculations, a high-precision fixture base that has passed machining is finally obtained.

[0020] In this embodiment of the invention, the blank of the fixture base undergoes rough machining to regulate its outline, laying a stable structural foundation for subsequent precision machining and reserving reasonable grinding and drilling allowances. Precision grinding is performed on the upper surface of the base, and flatness data monitoring and feedback control are used to ensure the flatness accuracy of the precision machining positioning surface, establishing a unified and accurate machining reference surface to realize the digitization of reference data for subsequent machining. Using the precision machining positioning surface as the data reference, uniform hole drilling is carried out. By collecting hole position and diameter data in real time and controlling tolerances in a closed loop, the uniformity of the distribution of each precision mounting hole is ensured, realizing digital control of hole position accuracy. The position and perpendicularity of each precision mounting hole are checked and calculated. The machining accuracy is verified by comparing the measured data, compliant machining results are selected, the machining quality of the high-precision fixture base is solidified, and a complete precision data verification closed loop is formed.

[0021] In a preferred embodiment of the present invention, step 200, based on a high-precision fixture base, involves installing an inner diameter expansion pin in each precision mounting hole, and ensuring that the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base, including: Step 201: Based on the high-precision fixture base, obtain the position coordinate data of each precision mounting hole as the installation positioning reference for the inner diameter expansion pin. Specifically, this includes: based on the high-precision fixture base that has undergone precision verification, using a spatial coordinate extraction algorithm, obtaining the measured center coordinates, hole axis azimuth angles, and center position data of 12 precision mounting holes on a 416mm diameter circumference; the spatial coordinate extraction algorithm uses precision measuring equipment to collect spatial point information of target feature points on the workpiece and converts the collected discrete point information into three-dimensional coordinate data in a unified coordinate system, thereby achieving a precise quantitative calculation method for feature positions; using the precision-machined positioning surface of the fixture base as the reference surface, with... A three-dimensional measurement coordinate system is established with the geometric center of the base as the origin. A spatial coordinate extraction algorithm is used to scan and calculate the spatial positions of each of the 12 precision mounting holes one by one, obtaining the three-dimensional center coordinates and spatial angle data of the hole axis of each mounting hole in a unified coordinate system. The above multiple sets of hole position data are normalized and transformed into a unified coordinate system, and abnormal data generated during the measurement process are eliminated and the data is smoothed to form a special positioning reference dataset suitable for the assembly of inner diameter expansion pins. Through one-to-one coordinate matching calculation, the unique installation position and standard assembly orientation of each inner diameter expansion pin on the fixture base are determined, providing a complete and reliable data foundation for subsequent orderly assembly and attitude control.

[0022] Step 202: Based on the installation positioning reference of the inner diameter expansion pins, each inner diameter expansion pin is sequentially installed into its corresponding precision mounting hole to obtain the initially installed inner diameter expansion pins. The axial orientation of each initially installed inner diameter expansion pin is adjusted to complete the orientation adjustment. Specifically, this includes: performing coordinate alignment calculations according to the preset numbers of the 12 precision mounting holes based on the installation positioning reference data of the inner diameter expansion pins. The preset numbers are based on the correspondence between the part mounting holes and the base mounting holes, starting from the preset reference axis of the base, and sequentially assigning unique sequential numbers to the 12 precision mounting holes in a clockwise direction along the circumference. This numbering method ensures a clear correspondence between hole positions and an orderly assembly path. The preset reference axis of the base is a reference axis that passes through the geometric center of the fixture base and coincides with the symmetrical center line of the countersunk mounting hole on the base used for machine tool fixation. This preset reference axis is calibrated by the center positioning mark of the base and the symmetrical structural features. The direction is confirmed and preset using the precision-machined positioning surface of the base as the reference plane. Combined with the three-dimensional coordinate correspondence, the guide direction and insertion depth of each inner diameter expansion pin are determined according to the coordinate difference. The 12 inner diameter expansion pins are then accurately guided into their matching precision mounting holes to complete the initial installation and positioning.

[0023] Using a guide fixture with the precision-machined positioning surface of the fixture base as a horizontal reference and the central axis of the base as a rotation reference, the spatial attitude of each inner diameter expansion pin is constrained and calibrated. The actual axial spatial data of each inner diameter expansion pin is collected, and the attitude is compared and calculated with the theoretical vertical axis. The tilt deviation of each expansion pin relative to the positioning surface, the circumferential deflection deviation relative to the central axis, and the radial runout deviation relative to the mounting hole are calculated respectively. The attitude correction amount is generated based on the calculation results of each deviation. The expansion pin is finely adjusted and calibrated according to the correction amount, so that the axis of all inner diameter expansion pins gradually converges to an attitude that is perpendicular to the positioning surface of the base, thus completing the attitude calibration calculation of the expansion pins of the entire hole system.

[0024] Step 203: The perpendicularity between the axis of each inner diameter expansion pin after attitude adjustment and the positioning surface of the base is checked to confirm that the perpendicularity meets the preset accuracy requirements. Specifically, this includes: using the precision-machined positioning surface of the fixture base as the reference plane for perpendicularity detection, collecting the spatial coordinates of the center point of the hole opening and the center point of the hole bottom for each inner diameter expansion pin after attitude adjustment, and uniformly incorporating the collected three-dimensional coordinate data into a three-dimensional measurement coordinate system based on the precision-machined positioning surface; the preset accuracy limit is a deviation allowable threshold preset based on the accuracy requirements of stress-free clamping of thin-walled parts for aero-engines, fixture assembly process standards, and the operating conditions of the inner diameter expansion pins. This limit is preset according to the assembly level of the fixture base, the fitting accuracy of the expansion pins, and the form and position tolerance requirements of the parts; the preset accuracy limit for single-hole perpendicularity is 0. The preset accuracy limits for hole system perpendicularity consistency and axis parallelism are both 0.02mm. Based on the spatial geometric perpendicularity constraint relationship, the coordinate data of the hole opening and hole bottom are calculated to solve the normal offset and angular offset of the actual axis of each inner diameter expansion pin relative to the reference plane. The perpendicularity deviation value of a single expansion pin is calculated based on the offset and angular offset. Using the perpendicularity deviation values ​​of all expansion pins as samples, the overall perpendicularity consistency deviation of the hole system and the parallelism deviation between each axis are calculated. The perpendicularity deviation of a single hole, the perpendicularity consistency deviation of the hole system, and the axis parallelism deviation are compared with the corresponding preset accuracy limits item by item and the compliance is judged. Deviations exceeding the limits are marked and fed back to the attitude calibration stage to complete the comprehensive verification calculation of the perpendicularity accuracy of the inner diameter expansion pins of the entire hole system.

[0025] Step 204: After confirming that the perpendicularity meets the preset accuracy requirements, each inner diameter expansion pin is initially fixed to maintain a stable relative position with the precision mounting hole, thereby obtaining a clamping system in which the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base. Specifically, the preset accuracy requirements are qualification criteria set for the perpendicularity of the inner diameter expansion pin axis to the precision-machined positioning surface of the fixture base. These requirements are preset based on the form and position tolerance requirements for the precision machining of thin-walled parts for aero-engines, the overall assembly process level of the fixture, and the stress-free assembly conditions of the inner diameter expansion pins. Specifically, the perpendicularity deviation of a single inner diameter expansion pin does not exceed 0.015mm, and the entire hole system... The perpendicularity consistency deviation and axis parallelism deviation of the expansion pins do not exceed 0.02mm. Under the premise that the perpendicularity deviation calculation results meet the preset accuracy requirements, a precision clearance measuring instrument is used to collect the circumferential and radial clearances between the outer wall of each of the 12 inner diameter expansion pins and the inner wall of the corresponding precision mounting holes at multiple points. The average and maximum clearance values ​​of each mating position are summarized and calculated to establish a single hole mating clearance characteristic database. Combining the material stiffness, structural dimensions, and rigidity distribution characteristics of the inner diameter expansion pins and the fixture base, the assembly stress distribution simulation calculation is carried out to analyze the local stress concentration and overall stress balance under different fixed parameters.

[0026] Based on the stress distribution calculation results, the optimal fixing torque value for each mounting hole position was determined. Simultaneously, the fixing sequence was calculated based on the circumferential distribution characteristics of the hole system, and a diagonally intersecting fixing sequence was planned to avoid posture deviation caused by unilateral tightening. Following the verified optimal fixing torque and diagonal fixing sequence, preliminary tightening operations were performed on each inner diameter expansion pin. After tightening, the pins were left to stand for a preset time, and the axial spatial coordinates and posture data of each inner diameter expansion pin were collected again. Post-fixing position retention calculations were performed, and the axial posture deviation and hole position coordinate deviation before and after tightening were compared to verify the relative positional stability of the expansion pins and precision mounting holes. This ensured that all inner diameter expansion pins continuously maintained a standard posture perpendicular to the precision-machined positioning surface of the base, completely eliminating the potential posture deviation caused by assembly stress. Ultimately, a stable clamping system with constant accuracy, uniform force, and suitable for stress-free clamping of thin-walled parts was constructed.

[0027] In this embodiment of the invention, a standardized assembly positioning basis is constructed by relying on the acquisition and benchmarking of precision mounting hole coordinate data, achieving precise quantification and data traceability of installation points, and ensuring the consistency of the assembly starting point of the inner diameter expansion pin; alignment assembly and attitude calibration are performed based on the positioning benchmark data, and assembly deviations are corrected by data comparison, improving the regularity of the axis attitude of each inner diameter expansion pin and eliminating positional errors caused by manual assembly; the verticality accuracy of the axis is verified by acquiring verticality data and performing accuracy comparison calculations, and a qualified judgment is completed based on the measured data, providing reliable data support for subsequent fixing; positioning and fixing are implemented based on compliant accuracy data, and the assembly stability is controlled by data, maintaining the vertical relationship between the expansion pin and the base positioning surface, and constructing a data-driven, uniformly stressed, stable, stress-free clamping system.

[0028] In a preferred embodiment of the present invention, step 300, which involves attaching the part to be processed to the positioning surface of the base with its designed reference surface to obtain initial positioning, includes: Step 301: Based on the clamping system where the axes of each inner diameter expansion pin are perpendicular to the positioning surface of the base, the positioning surface of the base is cleaned to remove surface impurities and obtain a clean positioning reference surface. Specifically, this includes: retrieving the perpendicularity and positional accuracy data retained from previous assembly stages of the clamping system, and performing a recalculation of the overall assembly stability of the clamping system; verifying whether the perpendicularity accuracy of each inner diameter expansion pin axis to the positioning surface of the base and the positional accuracy of the hole system remain in their original qualified state, completing the preliminary verification of the reliability of the clamping system reference; performing a thorough cleaning of the base positioning surface to remove chips, dust, and oil stains; and after cleaning, using a flatness tester to perform a full-area cleaning of the positioning surface. Multi-point data acquisition involves selecting the center, edge, and evenly distributed points of the positioning surface, collecting flatness values ​​at each point, and summarizing and calculating the overall flatness error of the positioning surface. Simultaneously, an impurity detection device is used to check for residues on the positioning surface, identifying and marking interference points corresponding to minor surface protrusions and adhering impurities. The collected flatness calculation data and impurity residue detection data are compared item by item with the preset reference surface accuracy threshold to determine whether the cleanliness and flatness accuracy of the positioning surface meet the requirements for part fitting and positioning. For substandard points, secondary cleaning and re-measurement are performed until all test data meet the accuracy standard. Finally, a clean positioning reference surface free of impurity interference and meeting the flatness standard is obtained, providing a stable and reliable positioning foundation for subsequent part reference fitting and coaxial alignment.

[0029] Step 302: Based on the clean positioning reference surface, place the part to be processed with its design reference surface facing the positioning surface of the base, so that the part and the base form a spatial pre-positioning posture; based on the spatial pre-positioning posture, make the design reference surface of the part and the positioning surface of the base form an initial reference fit state, and obtain the reference pre-fit state of the part and the base. Specifically, this includes: based on the clean positioning reference surface, retrieving the outline dimensions of the part to be processed, the flatness parameters of the design reference surface, and the outline dimensions and positioning surface boundary parameters of the fixture base, and importing the above-mentioned dimensional parameters into the three-dimensional assembly space for matching calculation, and carrying out multi-dimensional pre-simulation calculation of the part placement posture; through orientation offset simulation and interference risk investigation, and combined with the correspondence between the distribution of the part mounting holes and the arrangement of the base expansion pins, locking the initial placement orientation of the part, ensuring that the part is initially aligned with the base hole system when it is lowered; according to the calculated lowering path and placement orientation, use a clamping fixture to smoothly move the part to be processed with its design reference surface facing the positioning surface of the base, controlling the moving speed and horizontal tilt angle, so that the part and the base form a standardized and stable spatial pre-positioning posture.

[0030] Based on the pre-positioning posture in space, the initial height difference between the part's design reference surface and the base positioning surface is collected. The height difference is used to calculate and control the uniform lowering distance of the part, so that the part's design reference surface and the base positioning surface slowly approach and gradually contact each other. During this process, a gap detection element is used to collect real-time data from multiple points across the entire mating surface, calculate the mating gap difference at different points, and fine-tune the lowering angle of the part according to the gap difference to eliminate problems such as excessive local gaps or mating offsets, until the gap across the entire mating surface is uniform and meets the pre-matting accuracy requirements. Finally, a reference pre-matting state is obtained in which the part and the base reference surface are flat and the force is balanced, laying a stable foundation for subsequent hole pin axis deviation detection.

[0031] Step 303: Based on the reference pre-fitting state of the part and the base, obtain the positional deviation between the axis of each connecting hole on the mounting edge of the part and the axis of the corresponding inner diameter expansion pin; according to the positional deviation, perform fine-tuning of the displacement of the part to keep the axis of each connecting hole and the axis of the corresponding inner diameter expansion pin coaxially aligned, so as to obtain the alignment state of the part and the base. Specifically, this includes: based on the reference pre-fitting state of the part and the base, collecting the spatial coordinates of the axes of each connecting hole and the corresponding inner diameter expansion pin on the mounting edge of the part one by one, integrating the collected multiple sets of axis coordinate data into a unified three-dimensional measurement coordinate system for integrated processing, and obtaining the positional deviation between the axes of each set of holes and pins through coordinate difference calculation. Radial position deviation and angular offset deviation are summarized to form a position deviation dataset for the entire hole system. In this process, an arc length calculation algorithm is introduced. The arc length calculation algorithm is based on the circumferential uniform distribution characteristics of the hole system. Taking the geometric center of the base as the center, it calculates the arc length required for circumferential fine adjustment of the part based on the angular offset of the pin axis of a single hole and the radius parameter of the distribution circle. This is a precise calculation method that converts angular deviation into linear displacement. The arc length is calculated by combining the 12 evenly distributed distribution circles and the angular offset of a single hole. For example, for the working condition of a distribution circle diameter of 416mm and a single hole angular offset of 1°, the arc length calculation algorithm accurately obtains the circumferential fine adjustment arc length, providing a basis for the fine adjustment of the part.

[0032] Based on the radial position deviation and angular offset deviation values ​​in the deviation dataset, and combined with the circumferential fine-tuning arc length data obtained from the arc length calculation algorithm, the horizontal straight-line fine-tuning amount and the circumferential deflection fine-tuning amount are calculated simultaneously to determine the straight-line fine-tuning distance in the horizontal direction and the deflection arc length and deflection angle in the circumferential direction. According to the calculated complete set of fine-tuning parameters, the part is subjected to graded displacement fine-tuning using fine-tuning fixtures. First, the radial position deviation is corrected, and the circumferential angle deviation is corrected based on the arc length calculation results. The hole pin axis deviation is eliminated group by group. The axis coordinate data after fine-tuning is collected in real time and the deviation value is checked until the axis of each connecting hole is completely coaxially aligned with the corresponding inner diameter expansion pin axis. The coaxiality accuracy of the entire hole system meets the standard, and finally, the part and the base are aligned without deviation and with a regular posture.

[0033] Step 304: With the part aligned with the base, press the part vertically downwards so that its design reference surface is completely in contact with the positioning surface of the base, thereby obtaining the initial positioning of the part on the tooling. Specifically, this includes: after verifying that the part and the base are completely aligned coaxially, retrieving the measured flatness data of the precision-machined positioning surface of the base, the rigidity distribution characteristic data of the thin-walled part to be processed, and the weight parameters of the part itself, and combining the anti-deformation control requirements of thin-walled parts, carrying out the graded calculation of vertical downward pressure and the matching calculation of downward pressure speed, comprehensively calculating the pressure threshold of each area of ​​the part, and determining the segmented and stable downward pressure process parameters; at the same time, planning the vertical downward pressure travel path to avoid the risk of hole pin scraping and reference surface wear during the downward pressure process, and ensuring that the downward pressure action is completely adapted to the posture of the part and the tooling.

[0034] According to the calculated pressing process parameters, a controllable pressing fixture is used to press the part down slowly and uniformly in the vertical direction. During the pressing process, pressure distribution data of the reference mating surface is collected in real time through multi-point pressure sensing devices, and mating gap data of the entire area is collected simultaneously. The collected data is compared and calculated in real time. For points with uneven local pressure or large gaps, the posture is finely adjusted and corrected. Pressing continues until the design reference surface of the part is completely mated with the positioning surface of the base and the mating gap is stably reduced to within the design threshold. The mating accuracy is checked and calculated to verify the mating degree of the reference surface, the stability of the part's posture and the coaxiality of the hole and pin, and to verify the reliability of the initial positioning. Finally, the initial positioning state of the part with accurate position, stable posture and no deformation or displacement is obtained, laying a solid assembly foundation for subsequent stress-free clamping operations.

[0035] In this embodiment of the invention, the base positioning surface is pre-cleaned to remove surface impurities and interference factors, ensuring the flatness and cleanliness of the positioning reference surface, thus laying a reliable foundation for subsequent accurate positioning. Based on the clean positioning reference surface, the parts are pre-placed to standardize the spatial relative posture between the parts and the base, establishing an initial state of reference fit and ensuring the orderly connection of the positioning process. The axial position data of the part's connecting hole and the inner diameter expansion pin are collected, and the coaxial deviation is calculated through data comparison. Precise fine-tuning is then performed based on the deviation data to achieve coaxial alignment of the hole and pin axes, strengthening the data-driven control of positioning accuracy. A vertical pressing operation is then performed based on the aligned state to ensure complete fit between the part's reference surface and the base positioning surface. The initial positioning posture is stabilized based on the calibration results from the previous data, ensuring the consistency and stability of the part's positioning.

[0036] In a preferred embodiment of the present invention, step 400, based on the initial positioning, involves passing each inner diameter expansion pin through the corresponding connecting hole on the mounting edge of the part to establish a preliminary connection; based on the preliminary connection, pre-set feature points on the part are selected for measurement to obtain their spatial coordinate data and fit a virtual reference surface; after meshing the virtual reference surface, finite element numerical simulation is performed to obtain deformation prediction values; based on the deformation prediction values, compensation adjustment values ​​are calculated, including: Step 401: Based on the initial positioning of the part on the tooling, insert each inner diameter expansion pin into the corresponding connecting hole on the mounting edge of the part in sequence to obtain the engagement state of each inner diameter expansion pin and the connecting hole. Specifically, this includes: based on the initial positioning state of the part on the tooling confirmed by multiple checks, retrieving the three-dimensional coordinate data of the axis of each inner diameter expansion pin and the axis of the corresponding connecting hole of the part retained in the previous coaxial alignment process, performing a second check calculation on the above coordinate data, and calculating the coaxiality error of the pin axis. The preset allowable range is that the pin coaxiality error does not exceed 0.01mm. This range is calculated and preset in combination with the assembly accuracy standard of thin-walled parts of aero-engines, the tooling positioning accuracy level, and the machining tolerance of the connecting hole of the part, confirming the error. The value is within the preset allowable range, which serves as the core data basis for the expansion pin introduction. Based on the head taper dimension of the inner diameter expansion pin and the hole diameter tolerance parameters of the connecting hole, the initial introduction clearance and the introduction guide angle are calculated to determine the vertical movement speed and single movement stroke of the expansion pin. At the same time, preset operations are carried out, with the preset introduction resistance warning value being 15N. This value is determined by collecting normal friction resistance data of multiple sets of similar expansion pin introductions, combined with the anti-collision and anti-deformation requirements of thin-walled parts and the safety margin calculation. Simultaneously, the preset radial clearance allowable range is 0.005mm to 0.02mm. This range is preset based on the matching clearance requirements of the connecting hole diameter tolerance and the expansion pin outer diameter tolerance, as well as the introduction smoothness requirements.

[0037] The control transfer fixture drives each inner diameter expansion pin to move smoothly and uniformly along the vertical direction. According to the hole position number, the head of the expansion pin is sequentially inserted into the corresponding connecting hole. During the insertion process, the insertion resistance value is monitored in real time by the pressure sensing element, and the radial clearance data is collected in real time by the clearance detection element. The monitored data is compared and calculated in real time with the aforementioned preset threshold. For points where the resistance exceeds the 15N warning value or the clearance exceeds the range of 0.005mm to 0.02mm, the transfer posture is finely adjusted in time to correct the insertion deviation trend until the head of the expansion pin is fully inserted and the insertion state is stable and smooth. Finally, a precise alignment, no scraping, and no deviation are obtained between each inner diameter expansion pin and the corresponding connecting hole, laying a stable and reliable process foundation for subsequent expansion pin insertion operations.

[0038] Step 402: Based on the initial fit state, continue advancing each inner diameter expansion pin until its elastic sleeve completely passes through the connecting hole, thereby establishing a preliminary connection between the part and the tooling. Specifically, this includes: based on the initial fit state, collecting the effective length and total axial length parameters of the elastic sleeve of each individual inner diameter expansion pin; simultaneously measuring the wall thickness and chamfer dimensions of the corresponding connecting hole; summarizing and calculating these parameters; and combining them with the insertion depth data of the expansion pin head to calculate the target advancement stroke of a single inner diameter expansion pin; and considering the deformation resistance threshold of the thin-walled part material and the stiffness characteristics of the elastic sleeve itself. The appropriate uniform propulsion force was calculated to be 20N. The propulsion positioning criteria were set as follows: the propulsion displacement deviation was less than or equal to 0.02mm, and the deformation warning thresholds were set as follows: circumferential deformation was less than or equal to 0.01mm and axial deformation was less than or equal to 0.015mm. According to the approved propulsion stroke and force, the propulsion tool was controlled to drive each inner diameter expansion pin to feed uniformly along the axial direction. During the propulsion process, deformation detection elements were used to collect circumferential and axial deformation data of the elastic sleeve in real time. The positioning sensing element was used to capture the insertion positioning signal simultaneously. The collected data were compared and verified in real time to determine whether the propulsion status was compliant.

[0039] After confirming that the elastic sleeves of each inner diameter expansion pin have fully penetrated the corresponding connecting holes, that the sleeves have no abnormal deformation, and that there is no jamming or obstruction during advancement, the coaxiality coordinate data of the pins and holes is retrieved again to verify the relative positional accuracy of the parts and the tooling. The coaxiality of the pins and holes is checked to ensure that the pin axes maintain their original coaxial state. After confirming that there is no positional offset and no attitude deviation, the current advancement position of each inner diameter expansion pin is locked, and the connection structure between the parts and the tooling is formally established. Finally, a stable, reliable, accurate, and stress-free preliminary connection state is formed, laying a solid tooling foundation for subsequent feature point measurement and surface fitting operations.

[0040] Step 403: Based on the initial connection between the part and the tooling, determine several preset feature points on the part. These feature points include the edge points of each mounting hole and evenly distributed measurement points on the clean positioning reference surface, forming a set of feature points to be measured. Specifically, this includes: based on the initial connection state between the part and the tooling, combined with the thin-walled structural characteristics and design reference distribution of the part, conducting point position prediction analysis based on the three-dimensional design model of the part and the clamping conditions, and determining several preset feature points. The specific implementation process is as follows: sort out the key points of the part's precision machining form and position tolerance control, lock the mounting hole area and the positioning reference surface area as the core measurement area, combine the deformation sensitivity distribution law of thin-walled parts, exclude surface defect areas and structural stress concentration areas, and pre-set the selection type and point density of the feature points to be measured according to the layout principle of full coverage, highlighting key points and even distribution. The preset feature points are divided into two categories: one category is four points on the upper edge and four points on the lower edge of each mounting hole of the part, evenly distributed in a circle; the other category is eight measurement points on the positioning reference surface of the part arranged according to the principle of equal division of the circle. The two types of measurement points together constitute the core measurement points.

[0041] Based on the aforementioned preset rules, the measurement range of the entity is defined. The edge points of each mounting hole and the uniformly distributed measurement points on the positioning reference surface are selected as the measurement points. The selected measurement points are marked and classified one by one. The surface defects, collision areas and stress concentration areas of the parts are checked one by one. Invalid points in such areas are eliminated. Measurement points are added at adjacent equivalent positions and reclassified. Finally, a set of measurement feature points that covers the key areas of the parts, is evenly distributed and has regular points is formed, which defines a standardized and comprehensive measurement target for subsequent coordinate acquisition.

[0042] Step 404: Based on the set of feature points to be measured, coordinates of each feature point are acquired to obtain spatial coordinate data of each feature point, so as to obtain the measured coordinate dataset of the part in the current state, specifically including: Based on the pre-defined and standardized set of feature points to be measured, the high-precision 3D digital measurement equipment was preheated and calibrated to verify that the measurement error of the equipment met the preset accuracy requirements. The preset accuracy requirements were that the error of the equipment in a single measurement should not exceed 0.002 mm. This value was determined comprehensively based on the form and position tolerance control standards for thin-walled high-precision parts of aero-engines, the tooling positioning accuracy level, and the stability requirements of digital measurement conditions. After verification, the tooling and parts were placed as a whole in the standard measurement position of the measurement equipment. The angle of the equipment probe and the measurement optical path were adjusted to avoid measurement deviations caused by ambient light interference and reflections from the metal surface of the tooling. According to the numbering order of the feature points to be measured, the spatial coordinates of each feature point were collected one by one using the equipment probe. Each feature point was measured five times consecutively, and the coordinate values ​​of each single measurement were recorded simultaneously.

[0043] After completing multiple measurements at a single point, the dispersion of the multiple sets of measurement data at that point is calculated. Outliers that deviate too much from the median are filtered out and directly removed. The arithmetic mean of the remaining valid measurement data is calculated, and the calculated mean is used as the final measured coordinate of the feature point. After completing the measurement, outlier removal, and mean calculation of all the feature points to be measured in the above manner, the final measured coordinates of all feature points are systematically integrated according to the point number, establishing a complete data set with one-to-one correspondence between points and coordinates. This forms a measured coordinate dataset that accurately represents the current clamping posture of the part, realizing the digital and quantitative recording of the actual clamping shape of the part, and providing reliable data support for subsequent theoretical coordinate matching and surface fitting.

[0044] Step 405: Based on the measured coordinate dataset of the part in its current state, extract the theoretical coordinate data corresponding to each feature point in the part's design model to form a paired dataset of measured points and theoretical points. Specifically, this includes: based on the measured coordinate dataset formed after mean calculation and anomaly removal in the part's current clamping state, retrieving the pre-built complete 3D design model of the part. This model is constructed using 3D modeling software based on the design drawings, dimensional tolerances, and geometrical accuracy requirements of thin-walled aero-engine parts, progressively refining the structural contour, hole distribution, and datum surface features; after completing the basic model construction, importing the part's material parameters, assembly conditions, and machining constraints to proceed. Model training involves iterative simulations to optimize model accuracy and correct deviations between the model's shape and the actual part, ultimately forming a standard 3D design model that meets actual production needs. The reference coordinate system of the part's design model is retrieved, and the measurement coordinate system used for the actual measurements is uniformly transformed with the coordinate system of the part's design model, ensuring that the origin and axial directions of the two coordinate systems are completely consistent. Based on the numbering rules of the feature point set to be measured, theoretical points with the same numbers as each measured feature point are sequentially located in the 3D design model. The spatial coordinate data of each theoretical point in the unified coordinate system is extracted one by one, forming a theoretical coordinate dataset with the same number of measured points and corresponding numbers.

[0045] The measured coordinate dataset and the theoretical coordinate dataset were matched item by item according to the same point number. The coordinate correlation of each pair of data was verified. Data entries with mismatched numbers or incorrect point correspondence were identified and removed. Missing or mismatched pairings were re-completed and corrected. After the matching verification and correction of all points were completed, the measured coordinate data and theoretical coordinate data with consistent numbers and corresponding points were systematically integrated to form a paired dataset of measured points and theoretical points containing all valid feature points, with complete data and accurate correspondence. This laid the data foundation for subsequent surface fitting parameter solving and deviation distribution analysis.

[0046] Step 406: Based on the paired dataset of measured and theoretical points, the surface fitting parameters are solved with the goal of minimizing the sum of squared deviations between the measured and theoretical coordinates of each feature point. Specifically, this includes: using the paired dataset of measured and theoretical points, an optimization algorithm for the sum of squared deviations is introduced to solve the surface fitting parameters. The optimization algorithm uses the sum of squared differences between the measured and theoretical coordinates of each feature point as the optimization index. By iteratively reducing this sum, the fitted surface is made to infinitely closely approximate the actual and designed shape of the part. This algorithm takes into account both the balance of global deviations and the accuracy of local deviations, and is suitable for the fitting analysis of the surface shape of thin-walled parts. The optimization objective of the surface fitting is set, with the minimization of the sum of squared deviations between the measured and theoretical coordinates of each feature point as the core criterion. Combined with the surface features and curvature distribution of the part's reference surface, the surface fitting parameters are initialized and iterative calculation is started.

[0047] During the calculation process, single-set point deviation data are extracted in real time. Abnormal deviation items with excessive deviations from the mean are weighted and corrected to weaken the interference of abnormal data on the overall fitting results. After each iteration, the current sum of squares of deviation is calculated and compared with the previous calculation result to determine the optimization trend. The calculation is repeated until the fitting accuracy meets the preset requirements, that is, the fitting deviation of all points does not exceed 0.003mm. Finally, the surface fitting parameters are determined. For the eight feature points arranged on the circumference of the part positioning reference surface, the difference between the measured and theoretical coordinates of each point is extracted. The fitting parameters are gradually corrected through the deviation sum of squares optimization algorithm to minimize the deviation sum of squares. Finally, the surface fitting parameters adapted to the reference surface are obtained, which provides the core basis for the subsequent reconstruction of the virtual reference surface.

[0048] Step 407: Based on the surface fitting parameters, a virtual reference surface is obtained. The virtual reference surface represents the deviation distribution between the initial shape and the design shape of the part in the current clamping state. Specifically, this includes: based on the surface fitting parameters obtained after iterative optimization and deviation correction, retrieving the spatial coordinate boundary, curvature direction, and point distribution characteristics of the part's reference surface, importing the surface fitting parameters into the surface reconstruction operation module, and completing the matching and binding of parameters and model features; starting the surface reconstruction operation, which follows a preset surface generation rule. This rule takes the feature point coordinates as the core anchor point, adopts a global progressive splicing method, takes into account the continuity of surface curvature and the fit of points, and combines the design shape, processing accuracy requirements, and clamping deformation characteristics of the part's thin-walled reference surface in advance. According to the preset rule, the fitting data of each feature point is coherently spliced, and the surface shape of the entire reference surface is gradually deduced to obtain the initial virtual reference surface.

[0049] The initial virtual reference surface is smoothed to eliminate fitting burrs and abrupt changes in shape at local points, ensuring the overall continuity and regularity of the surface. The processed virtual reference surface is then compared point by point with the theoretical reference surface in the part design model using global coordinates. The coordinate differences of each corresponding point are extracted, and the deviation data is mapped to the corresponding area of ​​the virtual reference surface, fully presenting the deviation distribution between the actual shape and the design shape of the part under the current clamping state. The virtual reference surface is then verified for accuracy, confirming that the surface is free of distortion and that no deviation data is missing. This achieves the visualization and data-driven representation of clamping deviations, providing an accurate and reliable model foundation for subsequent finite element mesh generation and numerical simulation.

[0050] Step 408: Based on the virtual reference surface, spatial meshing is performed, discretizing the virtual reference surface into a finite number of mesh elements to form a finite element mesh model. Specifically, this includes: based on the reconstructed virtual reference surface, and considering the structural dimensions, surface curvature distribution, and deformation analysis accuracy requirements of the thin-walled part, spatial meshing calculations are performed. The specific meshing process involves determining the uniform base size and differentiated meshing density of the mesh elements based on the overall area and distribution of local curvature abrupt changes in the virtual reference surface. Large-size, low-density meshing is used for the central region of the reference surface with gentle curvature, while smaller, less dense meshing is used for areas with large curvature changes and holes. Deformation-sensitive areas such as the periphery are divided into small-sized, high-density meshes. Anchor points are divided using the outer contour boundary, inner hole edge, and feature measurement points of the virtual reference surface as the core, and the meshes are extended layer by layer along the surface normal direction. A quadrilateral mesh as the main type and a triangular mesh as the auxiliary type are used to divide the entire surface into regularly arranged and non-intersecting basic mesh units, thus completing the initial model construction. Mesh model training is carried out by importing parameters such as the material properties and clamping force characteristics of thin-walled parts, iteratively optimizing the basic mesh, verifying the fit and discretization rationality of the mesh units, correcting mesh arrangement deviations, and improving the model's ability to adapt to simulated working conditions.

[0051] After the initial mesh generation and model training meet the standards, the discreteness of the entire mesh is checked again based on the actual shape of the virtual reference surface to ensure that all mesh elements are evenly distributed and the number is suitable for the analysis requirements. The boundaries of each mesh are smoothed, and the entire mesh is checked one by one to accurately identify and eliminate distorted, overlapping, and missing meshes. Equivalent meshes are added to missing areas, and the mesh direction is regulated in disordered areas to eliminate mesh morphology defects. The mesh fitting accuracy is verified by comparing the contour overlap between the mesh model and the virtual reference surface. After confirming that the entire mesh is without deviation or anomalies, a complete finite element mesh model suitable for subsequent clamping force numerical simulation is finally formed.

[0052] Step 409: Based on the finite element mesh model, assign the elastic modulus and Poisson's ratio to the part material and load the preset clamping force boundary conditions to establish the finite element solution model. Specifically, this includes: based on the completed finite element mesh model, starting the overall construction process of the finite element solution model; retrieving the measured material performance parameters of the thin-walled part to be processed; verifying and assigning the elastic modulus and Poisson's ratio to the corresponding material in the model to ensure that the material properties are completely matched with the actual part; combining the tooling clamping and positioning conditions and the subsequent cutting and clamping process requirements, determining the clamping force loading points, loading values, constraint boundary ranges, and constraint stiffness conditions one by one; inputting the material property parameters, clamping loading parameters, and boundary constraint parameters into the model calculation system to complete the matching and binding of global parameters, and initially building the finite element solution model framework.

[0053] The finite element method (FEM) model was trained and optimized by importing stress and deformation data and tooling positioning error data under actual clamping conditions. Multiple rounds of iterative training were conducted on the initially built model to simulate real clamping stress scenarios, verify the consistency between the model's calculation results and actual working conditions, correct parameter assignment deviations, boundary constraint deviations, and loading position deviations, and mitigate the interference of abnormal data on calculation accuracy. After completing the iterative training, the model's solution accuracy and computational stability were verified to confirm that the model's calculation results closely match the actual clamping deformation patterns and that parameter transmission is distortion-free. Finally, a finite element method (FEM) model that fully conforms to actual clamping conditions and can be used for clamping force optimization analysis was established.

[0054] Step 410: Numerical simulation is performed based on the finite element solution model to solve the elastic deformation field of the part under the subsequent clamping force. The elastic deformation at the location of each inner diameter expansion pin is extracted as the deformation prediction value. Specifically, this includes: initializing the model operation environment based on the finite element solution model that has been built and trained and verified in the early stage, and verifying that the material parameters, boundary constraints and loading conditions are correct; starting the steady-state numerical simulation operation, using the preset clamping force as the loading parameter. The preset clamping force is 120N at a single point. This value is calculated and preset in combination with the deformation resistance limit of the thin-walled part material, the bearing capacity of the tooling inner diameter expansion pin, the fit accuracy of the part mounting hole, and the stability requirements of the processing conditions. This ensures the reliability of clamping and avoids plastic deformation of the part caused by excessive clamping force. During the operation, the stress transmission and deformation displacement of the whole domain nodes are tracked in real time, and the whole domain elastic deformation field of the part under the continuous action of the preset clamping force is solved step by step until the model operation reaches a steady-state convergence state.

[0055] After the numerical simulation calculations have fully converged, three-dimensional deformation data at each target location is extracted according to the mounting hole points corresponding to each inner diameter expansion pin. Invalid distorted data caused by mesh anomalies and calculation fluctuations are removed, and valid values ​​that conform to the elastic deformation law are retained. The arithmetic mean of multiple sets of valid deformation values ​​at a single point is calculated to eliminate local data deviations, and the calculated mean result is set as the final deformation prediction value for that point. According to the point numbering order, the deformation prediction value calculation for all points corresponding to the inner diameter expansion pins is completed one by one. The prediction data of all points are organized, classified and archived in an orderly manner to form a complete and traceable deformation prediction dataset, providing data support for subsequent clamping force optimization and clamping scheme adjustment.

[0056] Step 411: Based on the deformation prediction value, calculate the compensation adjustment value required for each inner diameter expansion pin during the clamping process. The compensation adjustment value is used to offset the offset caused by the initial form and position error and its own elastic deformation of the part in the subsequent clamping steps. Specifically, it includes: based on the deformation prediction value verified at the corresponding point of each inner diameter expansion pin, retrieving the initial form and position error data detected before the part is processed, sorting out the offset direction and offset amplitude requirements of elastic deformation, and establishing a single-point deformation compensation calculation benchmark; for each inner diameter expansion pin, perform reverse calculation of clamping stroke and locking force, superimpose the deformation prediction value and initial form and position error value at the corresponding point to determine the total compensation amplitude required at that point; combined with the transmission stiffness of the expansion pin itself and the displacement response characteristics of the clamping mechanism, calculate the clamping stroke compensation value and locking force compensation value of a single inner diameter expansion pin step by step, and summarize to obtain the preliminary compensation adjustment amount for a single point.

[0057] After completing the preliminary compensation adjustment calculation for all points, the accuracy verification process is initiated. The adjustment amounts for each point are substituted into the finite element solution model in reverse to simulate the clamping deformation state after compensation. The accuracy verification is then performed to check whether the adjustment amounts can completely offset the elastic deformation offset of the part and the initial form and position deviation. For points that fail the verification, have insufficient or excessive compensation amplitude, the calculation parameters are revised and recalculated until the verification is qualified. The adjustment amounts of each point that pass the verification are classified and organized to distinguish the compensation amplitude and compensation direction of different points, forming precise compensation adjustment values ​​for each point and with differentiation. This completely eliminates the superposition effect of clamping deformation and initial error, providing directly executable data for subsequent stress-free clamping operations.

[0058] In this embodiment of the invention, the inner diameter expansion pin is precisely inserted and fitted into the connecting hole of the part based on the initial positioning, standardizing the initial posture of the pin-hole fit and laying a stable foundation for subsequent connection operations; the inner diameter expansion pin is advanced to complete the insertion operation, establishing a reliable initial connection between the part and the tooling, ensuring the initial stability of the clamping structure; key feature points of the part are selected to construct a set of test points, realizing the standardized delineation of the test points and locking the precise target for subsequent coordinate acquisition; spatial coordinate data of each feature point are collected to form a complete measured coordinate dataset, realizing the digital quantitative representation of the part's clamping posture; measured coordinates and theoretical coordinate data are matched to construct a paired dataset, building the core data carrier for deviation analysis; the goal is to minimize deviation. Solving for fitting parameters ensures the accuracy and reliability of surface fitting; generating a virtual reference surface based on the fitting parameters visually represents the deviation distribution between the actual and designed shapes of the part, realizing the data-driven presentation of clamping deviations; meshing the virtual reference surface and constructing a discretized finite element mesh model to provide a standard carrier for numerical simulation; assigning material parameters and applying boundary conditions establishes a finite element solution model that fits the actual working conditions, improving the realism of the simulation analysis; conducting numerical simulation to solve the elastic deformation field and extracting the predicted deformation values ​​at corresponding locations to achieve early quantitative prediction of clamping deformation; calculating compensation adjustment values ​​based on the predicted deformation values ​​to provide data support for subsequent stress-free clamping and effectively offset the deformation offset of the part.

[0059] In a preferred embodiment of the present invention, step 500, which involves setting the driving torque for each inner diameter expansion pin according to the compensation adjustment value, and applying a tightening force to each inner diameter expansion pin according to the driving torque, causing the internal spindle to move axially and driving the elastic sleeve to achieve uniform radial elastic expansion, includes: Step 501: Convert the compensation adjustment value into the driving torque corresponding to each inner diameter expansion pin to obtain the driving torque setting value of each inner diameter expansion pin. Specifically, this includes: retrieving the differentiated compensation adjustment values ​​at different points formed after finite element simulation and accuracy verification; classifying and sorting the data according to the point number of the inner diameter expansion pin to ensure that the compensation adjustment value at each point corresponds one-to-one with the corresponding expansion pin; extracting the inherent parameters of the inner diameter expansion pin itself; sequentially entering the transmission coefficient, static friction loss of the mechanism, and dynamic torque transmission loss to establish a conversion benchmark between the compensation amount and the driving torque; wherein, the preset compensation amount is the displacement compensation amplitude that adapts to the clamping deformation offset requirement of thin-walled parts, and the preset torque is the execution loading threshold that matches the transmission characteristics of the expansion pin. Both are calculated and preset in combination with the elastic characteristics of the part material, the transmission efficiency of the inner diameter expansion pin mechanism, the clamping form and position tolerance control requirements, and the preliminary test calibration data.

[0060] For single-point compensation adjustment values, a step-by-step conversion is performed, deducting the corresponding mechanical transmission loss value to eliminate numerical deviations caused by mechanical transmission. Combining the preset compensation amount and torque correspondence, the corrected compensation adjustment value is converted into an initial torque value. The initial torque value is then checked for point compatibility, and its rationality is verified in conjunction with the clamping force requirements of thin-walled parts. After eliminating conversion deviations, the final drive torque setting value corresponding to each inner diameter expansion pin is determined, completing the accurate conversion of compensation data into execution parameters. All drive torque setting values ​​are uniformly archived and stored to provide a reliable basis for subsequent torque loading.

[0061] Step 502: Based on the driving torque setting value of each inner diameter expansion pin, tightening force is applied to the driving screw of each inner diameter expansion pin in sequence to obtain the torque loading completion status of each inner diameter expansion pin. Specifically, this includes: after completing the verification, validation, and archiving of the driving torque setting values ​​of all inner diameter expansion pins, based on the distribution characteristics of the part clamping points and the requirements for force balance, verifying and solidifying the preset point execution sequence. This point execution sequence is comprehensively preset by combining the stiffness distribution of the thin-walled structure of the part, the spacing of the connecting hole arrangement, and the principle of clamping force symmetry, prioritizing the selection of intermediate points with higher stiffness. The loading point serves as the starting point, extending symmetrically to both sides sequentially to eliminate the risk of force interference caused by disordered order, forming a standardized loading sequence. The driving torque setting value of the corresponding point is retrieved. This torque setting value is determined after conversion and verification of the previous compensation adjustment value, and is preset in advance in combination with the characteristics of the inner diameter expansion pin mechanism, the deformation resistance threshold of the part material, and the clamping fit requirements, taking into account both clamping stability and no deformation requirements. The high-precision torque actuator is called, and the output end of the actuator is aligned with the driving screw of a single inner diameter expansion pin, applying a directional tightening force according to the set torque value.

[0062] After the tightening operation is started, the loading torque value is collected and calculated in real time. The real-time loading value is compared with the preset torque setting value one by one, and the output force of the actuator is dynamically adjusted to keep the real-time loading value and the setting value in a consistent state. The torque loading value of a single point is continuously monitored. After the loading value collected for several consecutive times is stable without fluctuation or deviation, it is determined that the tightening force at that point has been applied, and the torque loading status of the inner diameter expansion pin is officially confirmed and obtained. After the single-point loading determination is completed, the torque actuator is immediately switched to the next loading point according to the established standardized loading sequence. The above tightening, monitoring, comparison and determination process is repeated to steadily promote the torque loading operation of all inner diameter expansion pins in the entire area. The entire process ensures that the loading at each point is orderly, without omissions or conflicts, and realizes the serialized and controllable execution of the tightening operation.

[0063] Step 503: Based on the torque loading completion status, confirm that each drive screw has been tightened according to the corresponding drive torque setting value, and obtain the pre-tightening status of each inner diameter expansion pin. Specifically, this includes: based on the overall working condition after torque loading is completed for all inner diameter expansion pins, starting a point-by-point verification process according to the preset point numbering order, sequentially collecting the actual loading torque value corresponding to each drive screw, and establishing a one-to-one correspondence between the actual loading data and the preset torque setting value; calculating the collected actual loading torque values ​​one by one, comparing the deviation between the actual loading value and the corresponding setting value, and checking for any abnormalities such as loading exceeding tolerance, not reaching the set threshold, missing loading, or repeated loading. The points of deviation are marked and the deviation values ​​are recorded. For the marked deviation points, the loading process data for those points is retrieved again to verify the standardization of the loading operation and the accuracy of the data acquisition. Minor deviations are corrected by secondary calibration, and for points with serious deviations, the torque loading operation is re-executed and verified again. After all points have been verified and corrected, and after a comprehensive check confirms that all drive screws have been tightened completely and in accordance with the corresponding drive torque settings, the loading status of each point is locked to prevent abnormal fluctuations in the loading values. This ensures a stable and consistent preload state for each inner diameter expansion pin, providing a solid and reliable force foundation for the subsequent axial feed of the mandrel and the expansion of the elastic sleeve mechanism.

[0064] Step 504: Based on the preload state of each inner diameter expansion pin, the drive screw of each inner diameter expansion pin drives the internal mandrel to feed axially under the action of preload force, obtaining the axial feed state of the mandrel. Specifically, this includes: based on the stable preload state determined after the inner diameter expansion pins have been verified and locked, combined with the internal transmission structure of the expansion pins, sorting out the transmission path of the preload force, calculating the transmission amplitude of the preload force from the drive screw to the end of the mandrel, eliminating the force loss value during the transmission process, and determining the effective axial thrust acting on the mandrel; under the continuous action of the stable preload force, the drive screw of each inner diameter expansion pin gradually transmits the circumferential tightening torque through the meshing transmission of the thread pair. The force is converted into a linear thrust along the axial direction. This thrust is continuously applied to the end of the mandrel, causing the mandrel inside the expansion pin to make a directional linear feed along the preset axial direction. During the feed process, the mandrel displacement data and preload value are collected in real time to establish the correspondence between displacement and thrust. The matching accuracy between the mandrel feed displacement and preload is controlled. Combined with the previously verified compensation and adjustment requirements, the feed stroke of the mandrel is precisely controlled to avoid overfeeding or underfeeding. The feed status is continuously monitored until the displacement value is stable and the force is stable, ultimately obtaining a stable and accurate axial feed state for the mandrel, providing a reliable displacement basis for the subsequent expansion drive of the elastic sleeve.

[0065] Step 505: Based on the axial feed state of the mandrel, the conical surface of the mandrel and the inner conical surface of the elastic sleeve slide relative to each other, driving the elastic sleeve to generate radial elastic expansion, thereby obtaining the radial expansion state of each elastic sleeve. Specifically, this includes: based on the stable axial feed state formed after precise control of the mandrel, retrieving structural parameters such as the preset mating angle and the sliding friction coefficient of the contact surface between the outer conical surface of the mandrel and the inner conical surface of the elastic sleeve; this preset mating angle is calculated comprehensively based on the material elastic limit and radial expansion stroke requirements of the elastic sleeve, while also taking into account the stability of the conical surface transmission and the requirement of no deformation when clamping thin-walled parts, and considering both force conversion efficiency and transmission smoothness, calculating the force conversion efficiency and loss amplitude of the conical surface contact transmission; during the continuous axial feed of the mandrel, the outer conical surface of the mandrel and the inner conical surface of the elastic sleeve slide relative to each other. The conical surfaces of the inner wall of the elastic sleeve gradually come into contact and generate smooth relative sliding along the contact slope. Through the inclined plane transmission effect of the conical surface, the axial feed force of the mandrel is gradually decomposed and transformed into a radial tightening force perpendicular to the inner wall of the sleeve, simultaneously eliminating the influence of contact surface friction loss on force transmission. The radial tightening force is uniformly applied to the entire inner wall of the elastic sleeve, driving the sleeve wall to produce uniform radial elastic deformation. During the deformation process, the mandrel feed displacement and the radial expansion dimension of the sleeve are collected in real time. The displacement data is correlated and compared with the expansion amplitude. According to the previously verified compensation adjustment requirements, the mandrel feed displacement is dynamically adjusted to limit the radial expansion amplitude and avoid excessive or insufficient expansion. After the radial expansion dimension is stable and the deformation is uniform and consistent throughout the entire area, a uniform and controllable radial expansion state of each elastic sleeve is finally obtained.

[0066] Step 506: Based on the radial expansion state, the outer wall of each elastic sleeve forms a uniform radial interference fit with the hole wall of the part connection hole to achieve uniform radial elastic expansion of each elastic sleeve. Specifically, this includes: based on the uniform radial expansion state formed after precise adjustment of each elastic sleeve, retrieving the designed inner diameter of the part connection hole and the original outer diameter of the elastic sleeve's outer wall, calculating the real-time fit clearance between the current radial expansion dimension of the elastic sleeve and the inner wall of the part connection hole, and simultaneously comparing the difference between the calculated value and the preset fit clearance threshold to determine the degree of clearance fit; wherein the preset fit clearance threshold is set to 0.02mm, this value is comprehensively preset based on the machining tolerance of the part connection hole, the expansion response accuracy of the elastic sleeve, and the requirement for scratch-free clamping of thin-walled parts; according to the calculated clearance difference, finely adjusting the axial feed displacement of the mandrel, thereby precisely controlling the radial expansion amplitude of the elastic sleeve, gradually reducing the fit clearance until the elastic sleeve... The outer wall of the sleeve is fully fitted to the wall of the connecting hole of the part. During the fitting process, the fitting pressure is monitored throughout to avoid excessive local pressure that could cause deformation of the part. After the fitting is uniform and the pressure is stable, the radial interference is further calculated and controlled within a preset reasonable range, which is set to 0.005mm to 0.015mm. This range is comprehensively preset based on the elastic deformation limit of the elastic sleeve, the deformation resistance of the thin-walled part, and the reliability of clamping. After the fitting is uniform and the pressure is stable, the radial interference is further calculated and controlled within the preset reasonable range of 0.005mm to 0.015mm, ultimately forming a uniform and dimensionally appropriate radial interference fit. The expansion pattern of the elastic sleeve is checked again to ensure that there is no local distortion or stress concentration throughout the process, achieving stable and uniform radial elastic expansion of each elastic sleeve, and ultimately achieving the goal of stress-free and high-precision clamping of thin-walled parts.

[0067] In this embodiment of the invention, the compensation adjustment value is converted into the corresponding drive torque setting value, realizing the precise docking of compensation data to execution parameters and ensuring that the torque setting is based on evidence; the tightening force is applied sequentially according to the torque setting value to realize the orderly execution of clamping force loading, avoid the force interference caused by synchronous loading, and ensure the stability of single-point loading; the torque loading completion status is confirmed to form a closed-loop verification of the execution link, eliminate the problem of missed tightening and incorrect tightening, and ensure the compliance and integrity of the tightening operation; the drive screw drives the mandrel to feed axially, realizing the stable transmission of torque to axial displacement, ensuring the smooth power transmission path and improving the consistency of the mechanism's action; the relative sliding of the mandrel conical surface and the inner conical surface of the elastic sleeve drives radial expansion, realizing the smooth conversion of axial force to radial force, ensuring uniform force on the sleeve expansion, and avoiding local deformation deviation; the outer wall of the elastic sleeve and the wall of the part connection hole form a uniform radial interference fit, realizing stress-free clamping, ensuring the clamping accuracy of the part, and maintaining the stability of the clamping state.

[0068] In a preferred embodiment of the present invention, step 600, based on radial elastic expansion, forms an interference fit between the elastic sleeve and the wall of the part mounting hole, transmitting the clamping force to the fixture base via the inner diameter expansion pin, thereby achieving a stress-free clamping state in the thin-walled region of the part, including: Step 601: Based on the uniform radial elastic expansion of each elastic sleeve, a uniform radial interference fit is formed between the outer wall of each elastic sleeve and the wall of the part mounting hole, obtaining the interference locking state between the part and each inner diameter expansion pin. Specifically, this includes: retrieving the uniform radial expansion parameters of the elastic sleeve determined by numerical simulation and accuracy verification in the early stage; simultaneously extracting the design inner diameter standard parameters of the part mounting hole and the real-time expansion dimension parameters of the outer wall of the elastic sleeve; completing the one-to-one matching of each set of parameters according to the point number of the inner diameter expansion pin; for a single group of elastic sleeves and corresponding part mounting holes, performing step-by-step calculation of the interference fit amplitude; calculating the actual outer diameter dimension of the elastic sleeve after expansion; calculating the difference between this dimension and the design inner diameter dimension of the part mounting hole to obtain the initial interference fit amplitude at a single point. The initial interference fit amplitude is compared and verified with the preset reasonable range, and abnormal data with excessive or insufficient amplitude are eliminated. After completing the amplitude calculation of a single point, the interference fit amplitude of each point in the entire region is further compared and verified laterally to check the uniformity of the amplitude of each point, and to identify local excessive or insufficient fit deviations. For points with deviations, the radial expansion amplitude of the elastic sleeve is finely adjusted to correct the amplitude difference. After the interference fit amplitude of each point in the entire region is within the preset reasonable range and uniform, the outer wall of each elastic sleeve is fully fitted with the hole wall of the part mounting hole to form a uniform and deviation-free radial interference fit in the entire region. This ensures a stable and secure connection between the part and each inner diameter expansion pin, and finally obtains a stable and reliable interference locking state between the part and each inner diameter expansion pin.

[0069] Step 602: Based on the interference-locked state, each inner diameter expansion pin transmits the clamping force along its axial direction to the connection interface between the inner diameter expansion pin and the precision mounting hole of the fixture base, obtaining the interface transmission state of the clamping force. Specifically, this includes: based on the interference-locked state, combined with the overall structural layout and assembly orientation of the inner diameter expansion pins, analyzing the clamping force transmission direction of each set of inner diameter expansion pins, planning the dedicated transmission path of the clamping force, and determining the force transmission relationship of each transmission node; calculating the axial force amplitude for each set of inner diameter expansion pins, collecting the initial clamping force value generated by the interference fit, separating the radial and axial components of the initial clamping force, and eliminating the mechanical loss and friction generated by the radial component during transmission. Various transmission losses, such as force loss, are calculated to obtain the effective clamping force amplitude acting on the axial direction. According to the planned transmission path, each inner diameter expansion pin is guided to transmit the calculated effective clamping force in a directional manner along its own axis, continuously advancing the clamping force transmission until it is completely transmitted to the connection interface between the inner diameter expansion pin and the precision mounting hole of the fixture base. After the clamping force is transmitted in place, the force distribution at the connection interface is fully verified, checking the degree of force fit across the entire interface, and investigating abnormalities such as clamping force leakage, transmission deviation, and uneven local force. Abnormal points are adjusted in a timely manner and re-verified. When the force at the connection interface is uniform and the clamping force transmission is without deviation or loss, a stable and orderly interface transmission state of clamping force is finally obtained.

[0070] Step 603: Based on the interface transmission state of the clamping force, establish a complete force flow path from the part through the inner diameter expansion pin to the fixture base to obtain a closed-loop force flow state. Specifically, this includes: based on the stable and orderly interface transmission state of the clamping force, dividing the clamping force transmission link into nodes, taking the mating position of the part mounting hole and the elastic sleeve as the force starting end, the inner diameter expansion pin body as the core force transmission carrier, and the connection position of the inner diameter expansion pin and the fixture base as the force ending point, determining the spatial orientation and connection relationship of each transmission node; according to the transmission sequence from the force starting end to the force ending point, sequentially calculating the force transmission amplitude of each node, recording the force loss value and transmission efficiency of each transmission path segment, and comparing adjacent nodes. The difference in force amplitude was analyzed to identify force discontinuities and weak points in the transmission path. For the identified force discontinuities, the node connection structure was optimized and the force transmission channel was supplemented. For the weak points, the clamping force transmission amplitude was adjusted and the node force stability was strengthened, and various defects in the transmission path were remedied. Based on the corrected transmission link, a complete force flow path was constructed from the part through the inner diameter expansion pin to the fixture base. The direction and amplitude of force flow transmission were controlled throughout the process to avoid abnormalities such as interruption, divergence, and leakage during force flow transmission. After the force flow path was fully connected and the force transmission was stable and without abnormalities, the overall force flow closed loop was reviewed and verified to finally obtain a stable, controllable, and complete closed force flow closed loop state.

[0071] Step 604: Based on the closed-loop force flow state, the clamping force is constrained within a local area of ​​the mounting hole of the part, obtaining a local constraint state of the clamping force. Based on this local constraint state, the clamping force is directly transmitted to the rigid fixture base via the inner diameter expansion pin, ensuring that the thin-walled area of ​​the part is always in a free state without external clamping force during clamping and subsequent processing, thereby obtaining a stress-free clamping state for the thin-walled area of ​​the part. Specifically, this includes: based on the stable closed-loop force flow state, combined with the structural distribution characteristics of the part and the coordinates of the mounting hole, defining the theoretical boundary of the clamping force, calculating the actual force coverage range of the clamping force, and precisely constraining the clamping force within a local area of ​​the mounting hole of the part by controlling the amplitude and direction of force flow transmission, blocking the diffusion channel of force flow to the surrounding area, and preventing the force range from extending outward, thus forming... The clamping force is locally constrained. Based on this local constraint, the overall transmission efficiency of the force flow in the transmission path is further calculated, the force retention at each transmission node is checked, and redundant losses in the transmission process are eliminated to ensure that the clamping force is directly and completely transmitted to the rigid fixture base through the inner diameter expansion pin body, avoiding force leakage to the thin-walled precision-machined area of ​​the part. At the same time, the stress of the thin-walled precision-machined area of ​​the part is verified in its entirety. The stress distribution is checked by using a multi-point synchronous monitoring method to confirm that there is no external clamping force or additional stress accumulation in the thin-walled area during the clamping process and the entire subsequent precision-machined process, and the area always maintains a free state free from external force interference. After repeated verification confirming that the force constraint is compliant and the thin-walled area is free from stress interference, a stable and reliable stress-free clamping state of the thin-walled area of ​​the part is finally obtained.

[0072] In this embodiment of the invention, uniform radial elastic expansion is used to achieve a uniform interference fit between the elastic sleeve and the wall of the mounting hole of the part, ensuring that the part and the inner diameter expansion pin are locked securely and the force is balanced, thus enhancing the consistency of clamping and positioning. Based on the stable interference locking state, the clamping force is guided to be transmitted directionally along the axis of the inner diameter expansion pin, avoiding force transmission deviation and local stress concentration, and improving the smoothness and controllability of clamping force interface transmission. A complete force flow path is constructed from the part to the inner diameter expansion pin and then to the fixture base, forming a closed-loop force transmission system, realizing full traceability and controllability of force flow transmission, and ensuring the closed-loop clamping force logic. According to the closed-loop force flow, the clamping force is locally constrained, and the force area is accurately defined based on the previous data calculation. The clamping force is directly transmitted to the rigid base, isolating the force interference in the thin-walled area, maintaining the free and stress-free state of the thin-walled area, and ensuring the precision of finishing and the integrity of the part's morphology.

[0073] like Figure 2 As shown, embodiments of the present invention also provide a stress-free clamping system for precision thin-walled components of aero-engines, comprising: The tooling preparation module is used to precision grind the upper end face of the fixture base blank to form a precision-machined positioning surface. Based on the precision-machined positioning surface, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Based on the high-precision fixture base, an inner diameter expansion pin is installed in each precision mounting hole, and the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base. The positioning module is used to align the part to be processed with its designed reference surface against the positioning surface of the base to obtain initial positioning; The measurement and compensation module is used to establish a preliminary connection by having each inner diameter expansion pin pass through the corresponding connection hole on the mounting edge of the part based on the initial positioning; based on the preliminary connection, it selects preset feature points on the part for measurement, obtains their spatial coordinate data, and fits them to obtain a virtual reference surface; after meshing the virtual reference surface, it performs finite element numerical simulation to obtain the deformation prediction value; and calculates the compensation adjustment value based on the deformation prediction value. The clamping actuator module is used to set the driving torque of each inner diameter expansion pin according to the compensation adjustment value; and to apply a tightening force to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. The implementation module is used to form an interference fit between the elastic sleeve and the wall of the mounting hole of the part based on radial elastic expansion, and to transmit the clamping force to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

[0074] It should be noted that this system is a system corresponding to the above method. All implementation methods in the above method embodiments are applicable to this embodiment and can achieve the same technical effect.

[0075] Embodiments of the present invention also provide a computing device, including: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A stress-free clamping method for precision thin-walled components of an aero-engine, characterized in that, The method includes: Step 100: Precision grinding is performed on the upper end face of the fixture base blank to form a precision positioning surface; using the precision positioning surface as a reference, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Step 200: Based on the high-precision fixture base, install an inner diameter expansion pin in each precision mounting hole, and make the axis of each inner diameter expansion pin perpendicular to the positioning surface of the base. Step 300: Place the part to be processed against the positioning surface of the base with its design reference surface to obtain initial positioning; Step 400: Based on the initial positioning, each inner diameter expansion pin passes through the corresponding connecting hole on the mounting edge of the part to establish a preliminary connection; based on the preliminary connection, preset feature points on the part are selected for measurement to obtain their spatial coordinate data and fit to obtain a virtual reference surface; after meshing the virtual reference surface, finite element numerical simulation is carried out to obtain the deformation prediction value; based on the deformation prediction value, the compensation adjustment value is calculated. Step 500: Based on the compensation adjustment value, set the driving torque for each inner diameter expansion pin; apply a tightening force to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. Step 600: Based on radial elastic expansion, the elastic sleeve forms an interference fit with the wall of the part mounting hole, and the clamping force is transmitted to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

2. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 1, characterized in that, Step 100 includes: A fixture base blank is provided, and its shape is roughly machined to form a preliminary base outline; Based on the preliminary base outline, the upper end face of the blank is precision ground to form a precision-machined positioning surface with high flatness requirements; Using the precision-machined positioning surface as a reference, multiple evenly distributed precision mounting holes are drilled on the circumference of the corresponding part mounting hole distribution circle. During the machining process, the position and diameter tolerance of each hole are controlled in real time to obtain each precision mounting hole after machining. The position and perpendicularity of each precision mounting hole are tested to confirm that their perpendicularity to the precision-machined positioning surface and their positional accuracy to each other meet the design requirements, thus obtaining a high-precision fixture base with precision mounting holes.

3. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 2, characterized in that, Step 200 includes: Based on the high-precision fixture base, the position coordinate data of each precision mounting hole are obtained as the installation positioning reference for the inner diameter expansion pin. Based on the installation positioning reference of the inner diameter expansion pin, each inner diameter expansion pin is sequentially installed into the corresponding precision mounting hole to obtain the initially installed inner diameter expansion pin; the axial posture of each initially installed inner diameter expansion pin is adjusted to complete the posture adjustment. The perpendicularity between the axis of each inner diameter expansion pin after attitude adjustment and the positioning surface of the base is checked to confirm that the perpendicularity meets the preset accuracy requirements. After confirming that its perpendicularity meets the preset accuracy requirements, each inner diameter expansion pin is initially fixed to maintain a stable relative position with the precision mounting hole, so as to obtain a clamping system in which the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base.

4. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 3, characterized in that, Step 300 includes: Based on the clamping system where the axes of each inner diameter expansion pin are perpendicular to the positioning surface of the base, the positioning surface of the base is cleaned to remove surface impurities and obtain a clean positioning reference surface. Based on the clean positioning reference surface, the part to be processed is placed with its design reference surface facing the positioning surface of the base, so that the part and the base form a spatial pre-positioning posture; based on the spatial pre-positioning posture, the design reference surface of the part and the positioning surface of the base form an initial reference fitting state, and the reference pre-fitting state of the part and the base is obtained. Based on the reference pre-fitting state of the part and the base, the positional deviation between the axis of each connecting hole on the mounting edge of the part and the axis of the corresponding inner diameter expansion pin is obtained; according to the positional deviation, the part is finely adjusted to keep the axis of each connecting hole coaxially aligned with the axis of the corresponding inner diameter expansion pin, so as to obtain the alignment state of the part and the base. With the part aligned with the base, press the part vertically down so that its design reference surface is fully aligned with the positioning surface of the base to obtain the initial positioning of the part on the tooling.

5. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 4, characterized in that, Step 400 includes: Based on the initial positioning of the part on the tooling, each inner diameter expansion pin is inserted into the corresponding connecting hole on the mounting side of the part in sequence to obtain the insertion and mating state of each inner diameter expansion pin and the connecting hole. Based on the aforementioned engagement state, continue to advance each inner diameter expansion pin until its elastic sleeve completely passes through the connecting hole, thereby establishing a preliminary connection between the part and the tooling. Based on the initial connection between the part and the tooling, several preset feature points are determined on the part. The feature points include the edge points of each mounting hole and the evenly distributed measuring points on the clean positioning reference surface, forming a set of feature points to be measured. Based on the set of feature points to be measured, coordinates of each feature point are collected to obtain spatial coordinate data of each feature point, so as to obtain the actual coordinate dataset of the part in the current state. Based on the measured coordinate dataset of the part in its current state, theoretical coordinate data corresponding to each feature point in the part design model are extracted to form a paired dataset of measured points and theoretical points. Based on a paired dataset of measured and theoretical points, the surface fitting parameters are solved with the goal of minimizing the sum of squared deviations between the measured and theoretical coordinates of each feature point. Based on the surface fitting parameters, a virtual reference surface is obtained, which represents the deviation distribution between the initial shape and the designed shape of the part in the current clamping state.

6. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 5, characterized in that, Step 400 further includes: Based on the virtual reference surface, a spatial mesh is generated, and the virtual reference surface is discretized into a finite number of mesh elements to form a finite element mesh model. Based on the finite element mesh model, the elastic modulus and Poisson's ratio of the part material are assigned, and a preset clamping force boundary condition is applied to establish a finite element solution model. Numerical simulation is carried out based on the finite element solution model to solve the elastic deformation field of the part under subsequent clamping force, and the elastic deformation at the location of each inner diameter expansion pin is extracted as the deformation prediction value. Based on the predicted deformation value, calculate the compensation adjustment value required for each inner diameter expansion pin during the clamping process; the compensation adjustment value is used to offset the offset of the part caused by the initial shape and position error and its own elastic deformation in subsequent clamping steps.

7. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 6, characterized in that, Step 500 includes: The compensation adjustment value is converted into the driving torque corresponding to each inner diameter expansion pin to obtain the driving torque setting value of each inner diameter expansion pin. Based on the driving torque setting value of each inner diameter expansion pin, tightening force is applied to the driving screw of each inner diameter expansion pin in sequence to obtain the torque loading completion state of each inner diameter expansion pin. Based on the torque loading completion status, it is confirmed that each drive screw has been tightened according to the corresponding drive torque setting value, and the pre-tightening status of each inner diameter expansion pin is obtained. Based on the preload state of each inner diameter expansion pin, the drive screw of each inner diameter expansion pin drives the internal spindle to feed axially under the action of preload force, thereby obtaining the axial feed state of the spindle. Based on the axial feed state of the mandrel, the conical surface of the mandrel and the inner conical surface of the elastic sleeve slide relative to each other, driving the elastic sleeve to produce radial elastic expansion, thereby obtaining the radial expansion state of each elastic sleeve. Based on the radial expansion state, the outer wall of each elastic sleeve and the hole wall of the part connection hole form a uniform radial interference fit to achieve uniform radial elastic expansion of each elastic sleeve.

8. The stress-free clamping method for precision thin-walled components of aero-engines according to claim 7, characterized in that, Step 600 includes: Based on the uniform radial elastic expansion of each elastic sleeve, a uniform radial interference fit is formed between the outer wall of each elastic sleeve and the hole wall of the part mounting hole, thereby obtaining an interference locking state between the part and each inner diameter expansion pin. Based on the interference locking state, each inner diameter expansion pin transmits the clamping force along its axial direction to the connection interface between the inner diameter expansion pin and the precision mounting hole of the fixture base, thereby obtaining the interface transmission state of the clamping force. Based on the interface transmission state of the clamping force, a complete force flow path of the clamping force from the part through the inner diameter expansion pin to the fixture base is established to obtain the closed loop state of the force flow. Based on the closed-loop state of force flow, the clamping force is constrained within a local area of ​​the mounting hole of the part, thus obtaining a local constraint state of the clamping force. Based on the local constraint state of the clamping force, the clamping force is directly transmitted to the rigid fixture base through the inner diameter expansion pin, so that the thin-walled area of ​​the part is always in a free state without external clamping force during the clamping process and subsequent processing, thereby obtaining a stress-free clamping state of the thin-walled area of ​​the part.

9. A stress-free clamping system for precision thin-walled components of an aero-engine, the system implementing the method as described in any one of claims 1 to 8, characterized in that, include: The tooling preparation module is used to perform precision grinding on the upper end face of the fixture base blank to form a precision positioning surface; using the precision positioning surface as a reference, multiple evenly distributed precision mounting holes are machined on the circumference of the corresponding part mounting hole distribution circle to obtain a high-precision fixture base. Based on a high-precision fixture base, an inner diameter expansion pin is installed in each precision mounting hole, and the axis of each inner diameter expansion pin is perpendicular to the positioning surface of the base. The positioning module is used to align the part to be processed with its designed reference surface against the positioning surface of the base to obtain initial positioning; The measurement and compensation module is used to establish a preliminary connection by having each inner diameter expansion pin pass through the corresponding connection hole on the mounting edge of the part based on the initial positioning; based on the preliminary connection, it selects preset feature points on the part for measurement, obtains their spatial coordinate data and fits them to obtain a virtual reference surface; after meshing the virtual reference surface, it performs finite element numerical simulation to obtain the deformation prediction value. Calculate the compensation adjustment value based on the predicted deformation value; The clamping actuator module is used to set the driving torque of each inner diameter expansion pin according to the compensation adjustment value; and to apply a tightening force to each inner diameter expansion pin according to the driving torque, so that the spindle inside moves axially and drives the elastic sleeve to achieve uniform radial elastic expansion. The implementation module is used to form an interference fit between the elastic sleeve and the wall of the mounting hole of the part based on radial elastic expansion, and to transmit the clamping force to the fixture base through the inner diameter expansion pin, so as to achieve a stress-free clamping state in the thin-walled area of ​​the part.

10. A computing device, characterized in that, include: One or more processors; A storage device for storing one or more programs, which, when executed by one or more processors, cause the one or more processors to implement the method as described in any one of claims 1 to 8.

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