An outer pre-adjusting clamping device for an aeronautical thin-walled cylindrical piece

Abstract

The application belongs to the field of aviation thin-walled part machining and clamping technology. It relates to an outer pre-adjusting clamping device for aviation thin-walled cylindrical parts. The device comprises a base plate, a first guide rail and a second guide rail arranged on the base plate, a front master disc tool fixed to one end of the base plate, a front clamping tool detachably positioned and connected to the front master disc tool, a tail support tool arranged in the inner hole of the tail part of the workpiece and provided with a radial adjustable support structure, a tail seat tool and an auxiliary support tool slidably arranged on the second guide rail, and a measurement assembly slidably arranged on the first guide rail. The device is positioned by the front self-centering expansion and the tail radial adjustable support, thereby reducing the clamping deformation. The detachable positioning cooperation realizes the overall quick replacement of the workpiece and high-precision repeated positioning. The measurement assembly can move axially to detect the outer circle runout, thereby realizing real-time calibration of the clamping precision.

Description

Technical Field

[0001] This invention relates to the field of machining and clamping technology for thin-walled aerospace parts, and specifically to an external pre-adjustment clamping device for thin-walled cylindrical aerospace parts. Background Technology

[0002] Thin-walled cylindrical parts for aerospace applications are prone to deformation during machining and clamping due to their low structural rigidity. Furthermore, their clamping efficiency and repeatability are insufficient to meet the high requirements of aerospace manufacturing. Existing clamping devices often focus on a single clamping function, lacking online detection and calibration methods for the accuracy of the clamped workpiece. This makes it impossible to effectively verify the clamping quality. In addition, their insufficient quick-change capability leads to long machine tool downtime for changeovers and low equipment utilization.

[0003] In the field of thin-walled cylindrical component inspection, patents such as CN116608793A have proposed non-contact dimensional inspection using laser displacement sensors on the inner and outer walls. However, these patents only focus on the measurement process and do not address the quick-change structure and low-stress clamping design of the clamping system. There is still room for research in clamping and inspection.

[0004] To address the aforementioned shortcomings, this invention provides an external pre-adjustment clamping device for thin-walled cylindrical aerospace components. It achieves rapid overall workpiece replacement and micron-level repeatable positioning through the zero-point positioning quick-change cooperation between the front master disc fixture and the front clamping fixture. The synergistic effect of the front self-centering expansion clamp, the rear radially adjustable support, and auxiliary supports effectively suppresses thin-walled clamping deformation. Furthermore, it integrates measurement components to detect outer diameter runout and identify defects after clamping, forming a closed-loop feedback system for clamping, detection, and calibration. This systematically solves the problems of easy clamping deformation, low replacement efficiency, and lack of detection methods. Summary of the Invention

[0005] The present invention aims to provide a clamping device for thin-walled cylindrical parts in aerospace, in order to solve the problems of easy deformation during clamping, low replacement efficiency and lack of detection means in the prior art.

[0006] An external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace includes a base plate, a front master plate fixture, a front clamping fixture, a tailstock fixture, a tail support fixture, an auxiliary support fixture, and a measuring component. The base plate is provided with a first guide rail and a second guide rail. The measuring component is slidably mounted on the first guide rail, and the tailstock fixture and auxiliary support fixture are slidably mounted on the second guide rail. The front mother plate fixture is fixed to one end of the base plate, and the front clamping fixture is detachably positioned and connected to it to support the inner hole of the front end of the cylindrical workpiece. Tail support fixture, used to insert into the inner hole of the tail of the workpiece, is provided with a radially adjustable support structure to fit the inner hole wall of the workpiece. The tailstock fixture moves and locks along the second guide rail. It is equipped with a center point for pressing against the center of the tail support fixture, thereby achieving axial and radial positioning of the tail support fixture. The measuring component moves along the first guide rail to any axial position on the workpiece. The front end of the thin-walled cylindrical workpiece is positioned by the front clamping fixture, while the rear end is inserted into the tail support fixture and secured and centered by the tailstock fixture, forming an offline pre-adjusted clamping layout for the machine tool. The front master plate fixture and the front clamping fixture are detachably positioned together, enabling quick and accurate repetitive positioning of the entire fixture with the workpiece, reducing machine tool downtime for changing fixtures and improving equipment utilization. Both the tailstock fixture and the auxiliary support fixture can slide and lock along the second guide rail, adapting to workpieces of different lengths and specifications, and the device has a wide range of compatibility. The radially adjustable support structure of the tail support fixture can fit against the inner wall of the workpiece's inner hole, compensating for deviations in the inner hole size of the workpiece's tail end, eliminating support gaps, and increasing the inner hole support contact area, effectively reducing the clamping deformation of thin-walled workpieces. The auxiliary support fixture supports the outer wall of the workpiece, enhancing the overall rigidity of the clamping and suppressing machining vibration. The measuring component can move along the guide rail to any axial position of the workpiece, detect the runout of the outer circle of the workpiece after clamping, realize real-time calibration of clamping accuracy, and ensure the form and position tolerance of the workpiece machining.

[0007] Optionally, the tail support fixture includes a first base, several semi-circular sliders, an adjusting screw, and a center block; The first base has a radial groove corresponding to the semi-circular slider. The adjusting screw is connected to the first base along the radial thread, and the inner end of the adjusting screw is in transmission cooperation with the semi-circular slider. Rotating the adjusting screw can drive the semi-circular slider to move radially along the radial groove, so that the outer arc surface of the semi-circular slider fits against the inner wall of the workpiece's inner hole. The center block is fixedly installed at the center of the first base near the tailstock fixture, and the center can be pressed tightly into the center hole of the center block. This tail support fixture adopts a radial transmission structure of adjusting screw and semi-circular slider. By rotating the adjusting screw, the semi-circular slider can be driven to slide precisely along the radial groove of the base. The radial extension of each support point can be adjusted independently to adapt to the dimensional deviation and form and position error of the inner hole of the workpiece tail, completely eliminating support gaps and significantly improving tail positioning accuracy. The outer arc surface of the semi-circular slider fits against the inner wall of the workpiece hole, effectively increasing the support contact area, dispersing local stress, greatly reducing the clamping deformation of thin-walled workpieces, and ensuring the roundness accuracy of the inner hole of the workpiece. The center block set at the center of the base can precisely cooperate with the tailstock center to achieve coaxial centering and axial locking of the tail support fixture, ensuring the coaxiality of the workpiece clamping; the radial groove provides stable guidance for the semi-circular slider, and the threaded transmission structure has self-locking characteristics, ensuring a stable and reliable support state and eliminating the risk of loosening or displacement after clamping.

[0008] Furthermore, the front clamping fixture includes a second base, several semi-circular claws, a sliding positioning block, a rear pull rod, a threaded block, a zero-point pin, and a coarse positioning pin; The second base has a front face and a rear face. The sliding positioning block is fixedly installed on the front end face. The sliding positioning block is provided with a guide groove, and each semi-circular claw is slidably assembled in the radial guide groove of the corresponding sliding positioning block. The rear tie rod is coaxially inserted into the central through hole of the second base. The outer periphery of the front end of the rear tie rod is tapered, and the inner end of each semi-circular claw is provided with an inner inclined surface that matches the tapered surface. The rear end of the rear tie rod is provided with an external thread section that is threaded into the threaded block. The rear end face of the rear tie rod is provided with an internal hexagonal operating hole. When the pull rod is rotated to make it move backward axially, the semicircular claws are driven to expand outward radially synchronously through the cooperation of the tapered surface and the inner inclined surface, which tightens the inner hole at the front end of the workpiece to achieve self-centering clamping. The semicircular claws are provided with limiting holes for placing limiting blocks. Both the zero-point pin and the coarse positioning pin are fixedly set on the rear end face for positioning and engagement with the front master disc tooling.

[0009] This front clamping fixture employs a multi-jaw self-centering structure with wedge-face drive, providing clear and controllable clamping and assembly steps while offering both high centering accuracy and ease of operation. When pre-loading the workpiece, the inner hole at the front end of the cylindrical workpiece is first fitted onto the outer circumference of each semi-circular jaw. The radial guide groove of the sliding positioning block provides precise sliding constraints for the semi-circular jaws, ensuring that each jaw moves only radially without circumferential offset. A single hexagonal tool is used to rotate the pull rod from the rear end of the fixture. Axial retraction is achieved through the threaded engagement between the pull rod and the threaded block. The wedge-face drive between the front conical surface and the inner inclined surface of the semi-circular jaws synchronously drives all the semi-circular jaws to expand radially outward, tightening the inner hole at the front end of the workpiece and completing self-centering clamping. Each semi-circular jaw has a limiting hole for inserting a limiting block; the limiting block and the limiting hole have a clearance fit to prevent excessive radial movement of the semi-circular jaws from damaging the inner hole of the workpiece. Single-point operation achieves synchronous tightening of the multiple jaws, making the clamping process simple and efficient. The clamping force is evenly distributed circumferentially, effectively reducing localized clamping deformation of thin-walled workpieces. The tooling rear end face is integrated with coarse positioning pins and zero-point pins. When docking with the front mother plate tooling, the coarse positioning pins first complete the initial positioning and guidance, and then the zero-point pins achieve high-precision locking and positioning. The docking steps are clearly hierarchical, which can ensure that the tooling after offline pre-assembly can be quickly put on the machine for replacement, and the repeatability positioning accuracy is stable and reliable.

[0010] Specifically, the front master plate fixture includes a master plate and several zero-point seats. The zero-point seats are fixedly installed on the front end face of the master plate, and each zero-point seat corresponds to a zero-point pin, used to achieve rapid positioning and pneumatic locking of the front clamping fixture. This front master plate fixture has zero-point seats arranged on the end face of the master plate, each corresponding to a zero-point pin. The zero-point seats are a mature existing technology, and pneumatic zero-point positioning fixtures from Ingenic can be used, simultaneously achieving high-precision positioning and pneumatic locking of the front clamping fixture. The zero-point seats employ a pneumatic unlocking and spring mechanical locking mechanism, completing positioning and clamping actions in one step, with rapid tooling assembly and disassembly switching response. Its repeatability positioning accuracy can reach the micrometer level, ensuring positioning consistency during multiple assembly / disassembly of the front clamping fixture and effectively eliminating accumulated clamping errors. In the locked state, stable clamping force can be maintained without continuous air supply, exhibiting strong adaptability to working conditions. The multi-point coordinated arrangement provides sufficient connection rigidity and stable bearing of processing loads. With the matching master disk configuration of the machine tool station and offline pre-adjustment table, the pre-installed front clamping fixture can be quickly transferred to the machine along with the workpiece, greatly reducing the downtime for machine tool changeover and alignment, improving equipment processing utilization, and ensuring the reliability of workpiece machining form and position tolerances.

[0011] Furthermore, it also includes a rotary joint device and an external rotary motor; The rotary joint device includes a fixed outer shell and an inner ring that can rotate relative to the outer shell. The inner ring is connected to the mother disc by a connector. The outer shell is provided with an air inlet to access an external air passage for supplying compressed air to the zero point seat. An external rotary motor connects to the inner ring end to drive its rotation. This clamping device incorporates a rotary joint and an external rotary motor, designed to closely match the working characteristics of the zero-point seat. The zero-point seat opens when air is supplied and locks when air is cut off. The rotary joint housing has an air inlet connected to the external air circuit, and the inner ring is synchronously connected to the front master plate fixture. During clamping, air is first supplied to the zero-point seat through the air inlet to open it. The zero-point pin of the front clamping fixture is then placed into the zero-point seat, and the air supply is cut off to lock it, fixing the front clamping fixture onto the master plate. The workpiece is then installed. After inspection, the workpiece is removed, and air is supplied again to open the zero-point seat, allowing the zero-point pin to be removed along with the front clamping fixture. The rotary joint maintains continuous airflow during workpiece rotation inspection, preventing pipe entanglement and ensuring stable and reliable unlocking and locking actions. The external rotary motor drives the master plate to rotate, working in conjunction with the measuring components to complete continuous full-circumference outer diameter runout inspection, improving alignment efficiency and accuracy. The entire process realizes a closed-loop operation of ventilation insertion, air cut-off locking, and ventilation removal, which effectively improves the efficiency of equipment replacement and the accuracy of repeatability.

[0012] Optionally, the tailstock tooling includes a tailstock, a mounting plate, and a locking plate; The mounting plate slides onto the second guide rail, and the tailstock is fixedly mounted on the mounting plate. The base plate has a T-slot, and the locking plate engages with the T-slot via bolts to lock the tailstock in place at the corresponding position on the second guide rail. This tailstock fixture employs a combination structure of sliding guidance from the mounting plate and locking via the T-slot of the locking plate. The sliding engagement between the mounting plate and the second guide rail allows the tailstock to slide freely along the workpiece axis, adapting to thin-walled cylindrical workpieces of varying lengths. The device has a wide axial compatibility range. The guide rail provides precise guidance for the tailstock's sliding, ensuring that the tailstock's tip always maintains a coaxial movement trajectory with the workpiece, preventing coaxiality deviations during adjustment. The locking plate engages with the T-slot of the base plate, enabling reliable locking at any position within the guide rail's travel range. After locking, the tailstock exhibits no axial movement, stably outputting the tip's clamping force, ensuring the axial and radial positioning accuracy of the tail support fixture, and providing sufficient tail support rigidity for the workpiece. Furthermore, the position adjustment and locking operations are convenient, allowing for rapid clamping and adaptation of workpieces of different lengths, effectively improving pre-adjustment efficiency.

[0013] Optionally, the measuring components include a mounting plate, a vertical bar, a horizontal bar, and a dial indicator; The fixed plate is slidably mounted on the first guide rail, the vertical rod is vertically fixed on the fixed plate, and the horizontal rod is horizontally mounted on the vertical rod and can be adjusted up and down along the vertical rod. The dial indicator is mounted on the horizontal rod and can move horizontally along the horizontal rod to detect the outer diameter runout and end face flatness of the workpiece at different positions. This measuring assembly adopts a multi-dimensional adjustable mounting structure, which can flexibly adapt to the clamping accuracy detection requirements of workpieces of different specifications. The fixed plate slides axially along the first guide rail, which can drive the dial indicator to any axial position of the workpiece, covering the detection of the outer diameter runout of the entire length of the workpiece, and adapting to thin-walled cylindrical workpieces of different lengths; the horizontal rod can be vertically raised and lowered along the vertical rod, which can match the size of workpieces with different outer diameters and broaden the specification compatibility range of the device; the dial indicator can slide horizontally along the horizontal rod, which can be aligned with the outer diameter of the workpiece to detect radial runout, or moved to the end face of the workpiece to detect flatness, while meeting the detection requirements of outer diameter coaxiality alignment and end face flatness. The overall adjustment operation is simple and the measurement position switching is flexible. It can complete the clamping accuracy verification in multiple positions and dimensions without repeatedly disassembling and assembling the probe, effectively improving the pre-adjustment alignment efficiency and calibration accuracy, and ensuring the stability of the form and position tolerances of the workpiece after clamping.

[0014] Optionally, the upper end of the auxiliary support fixture is equipped with a bearing that can roll in contact with the outer diameter of the workpiece to support the outer wall of the workpiece and enhance clamping rigidity. This auxiliary support fixture employs a bearing-workpiece rolling contact support structure, which can effectively support the outer wall of thin-walled cylindrical workpieces, compensating for the workpiece's insufficient rigidity, significantly enhancing the overall rigidity of the clamping system, and effectively suppressing workpiece vibration and bending deformation during clamping, calibration, and machining. The bearing and workpiece outer diameter are in rolling contact, resulting in low frictional resistance during circumferential rotation of the workpiece. This prevents scratching the workpiece's outer surface and avoids interfering with its rotation, making it suitable for calibration conditions involving workpiece rotation and dial indicator use. The auxiliary support fixture can slide axially along the guide rail to adjust its support position, providing targeted support for weak sections of the workpiece, adapting to workpieces of different lengths, further improving the stability and adaptability of the clamping system, and ensuring the reliability of the workpiece's machining shape and position accuracy.

[0015] Alternatively, the measurement components include multiple laser displacement sensors, an angle encoder, an electric slider, and a data processing module arranged along the circumference of the workpiece; The data processing module controls the electric slider to drive the measuring component to scan axially along the first guide rail, and collects the circumferential displacement sequence of each laser displacement sensor at each axial section as the workpiece rotates. The data processing module performs differential comparisons on the displacement sequence along the circumferential direction to identify extreme points, and selects extreme points whose amplitude deviates from the mean of the cross-section by more than a set number of standard deviations as candidate anomalies. This measurement component employs a circumferential arrangement of multiple laser displacement sensors in conjunction with an angle encoder, enabling simultaneous acquisition of full-circumferential contour data during low-speed workpiece rotation. Compared to single-sensor segmented detection schemes, this significantly improves detection efficiency and ensures complete contour coverage without omissions. The data processing module controls the measurement component to step-scan along the guide rail axis, achieving automated contour acquisition along the entire length of the workpiece without the need for manual point-by-point alignment, resulting in high operational efficiency. An adaptive amplitude threshold based on the cross-sectional mean is used to filter candidate anomalies, effectively eliminating systematic deviations introduced by differences in workpiece outer diameter and installation eccentricity. This makes candidate anomaly extraction insensitive to individual workpiece differences, resulting in strong detection robustness.

[0016] Furthermore, the data processing module extracts displacement data within a local window for each candidate anomaly point, and makes a comprehensive judgment based on the displacement change amplitude and morphological characteristics within the local area. If the preset defect judgment conditions are met, it is confirmed as a real defect point, and the concavity / convexity type of the defect is determined based on the morphological characteristics. The data processing module also cross-validates the circumferential and axial detection results, retaining only defect points identified simultaneously in both directions, and outputting the axial position, circumferential angle, and radial amplitude of each defect point. This measurement component, based on a comprehensive judgment of displacement variation amplitude and morphological characteristics within a local window, can accurately distinguish between real defects and noise pseudo-signals, avoiding misjudging surface roughness fluctuations or sensor noise as defects. It can also preliminarily determine the concavity / convexity type of defects based on the combination of rising and falling edges of the displacement sequence within the window, providing a basis for subsequent defect classification. Cross-validating the circumferential and axial detection results, retaining only defect points identified simultaneously in both directions, effectively eliminates pseudo-signals generated by accidental factors (such as local vibration or surface texture interference) in a single direction, significantly reducing the false detection rate and ensuring the reliability of the detection results. Finally, the axial position, circumferential angle, and radial amplitude of each defect point are output, providing quantitative data support for subsequent quality grading, defect repair location, and processing technology adjustment.

[0017] Specifically, the data processing module extracts local windows centered on the cross-validated defect points in both the circumferential and axial directions. A predetermined fitting function is used to fit the displacement data within each window. Through iterative optimization, the defect center position, maximum amplitude, and influence width parameters that ensure the fitting residuals meet the convergence condition are determined. The fitted center position is used as the precise coordinates of the defect point, and the spatial influence range of the defect point is defined by a preset multiple of the influence width. The circumferential and axial fitting results are combined to obtain the precise three-dimensional center coordinates of each defect point and its bidirectional circumferential and axial influence ranges. Iterative optimization of the displacement data within each window using a predetermined fitting function achieves high-sampling-level accuracy in obtaining the defect center position, maximum amplitude, and influence width parameters, significantly improving defect positioning accuracy and amplitude quantification accuracy. Using the fitted center position as the precise three-dimensional coordinates of the defect point and defining the spatial influence range by a preset multiple of the influence width enables quantitative characterization of the defect's geometric scale. Combining the circumferential and axial fitting results provides complete and quantitative data support for subsequent defect morphology classification, repair path planning, and workpiece condition determination.

[0018] More specifically, the data processing module classifies defect morphology based on the ratio of the axial to the circumferential influence range of the defect point, and determines the workpiece status according to the defect amplitude. Based on the ratio, defects are categorized as point-like, equiaxial, or strip-like, providing a quantitative basis for determining the stress severity and repair priority of various defects, thus standardizing and automating defect morphology identification. Workpieces are automatically classified as qualified, repairable, or scrapped according to preset amplitude thresholds, achieving automatic quality level determination and avoiding subjective human error. For repairable products, the module outputs the defect category, location, and influence range, providing precise repair guidance for subsequent reprocessing, helping to reduce scrap rates and improve manufacturing economy. Finally, a comprehensive inspection report is generated, including defect statistics and a 3D model mapping, making the inspection results intuitive and visual, facilitating quality traceability and process improvement.

[0019] This invention breaks through the limitations of traditional single clamping or single inspection methods, constructing a systematic solution integrating offline pre-adjustment quick change, multi-point collaborative low-stress clamping, and online inspection and real-time calibration. Through the zero-point positioning quick change cooperation between the front master plate fixture and the front clamping fixture, it enables rapid overall workpiece changeover and micron-level repeatable positioning, significantly reducing machine tool downtime. The synergistic effect of the front self-centering expansion clamp, the rear radially adjustable support, and auxiliary supports not only compensates for workpiece dimensional deviations but also increases the support area, effectively suppressing thin-walled clamping deformation. Simultaneously, the measuring components can directly perform external cylindrical runout detection and surface defect identification after clamping, forming a closed-loop feedback of clamping, inspection, and calibration, ensuring the consistency and reliability of machining accuracy for aerospace thin-walled cylindrical parts. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall device of the present invention.

[0022] Figure 2 This is a schematic diagram of the tail support fixture of the present invention.

[0023] Figure 3 This is a schematic diagram of the semi-circular slider and adjusting screw of the present invention.

[0024] Figure 4 This is a schematic diagram of the tailstock tooling of the present invention.

[0025] Figure 5 This is a schematic diagram of the measurement component in Example 1.

[0026] Figure 6 This is a schematic diagram of the front end face of the front clamping fixture.

[0027] Figure 7 This is a schematic diagram of the rear end face of the front clamping fixture.

[0028] Figure 8 A schematic diagram showing the front clamping fixture concealing the second base.

[0029] Figure 9 This is a sectional view of the front clamping fixture.

[0030] Figure 10 This is a schematic diagram of the guide groove.

[0031] Figure 11 This is a schematic diagram of the front master disc tooling.

[0032] Figure 12 This is a schematic diagram of a rotary joint device.

[0033] Figure 13 This is a cross-sectional view of the rotary joint.

[0034] Figure 14 This is a schematic diagram of the tailstock tooling and the T-slot mating.

[0035] Figure 15 This is a schematic diagram of the auxiliary support tooling.

[0036] Figure 16 This is a schematic diagram of the measurement component in Example 2.

[0037] Figure 17 This is a schematic diagram of the laser displacement sensor placement in Example 2.

[0038] Figure Descriptions: 1-Front master disc fixture, 2-Front clamping fixture, 3-Tailstock fixture, 4-Tail support fixture, 5-Auxiliary support fixture, 6-Measuring assembly, 7-Base plate, 8-Cylindrical workpiece, 9-Rotary joint device, 11-Master disc, 12-Zero point seat, 21-Second base, 21a-Front end face, 21b-Rear end face, 22-Semi-circular claw, 22a-Inner inclined surface, 22b-Limiting block, 23-Slide positioning block, 23a-Guide groove, 24-Rear pull rod, 24a-Conical surface, 24b-Internal hexagonal operating hole, 2 5-Threaded block, 26-Zero point pin, 27-Coarse positioning pin, 31-Center, 32-Mounting plate, 33-Locking plate, 34-Tailstock, 41-First base, 41a-Radial groove, 42-Semi-circular slider, 43-Adjusting screw, 44-Center block, 51-Bearing, 61-Fixing plate, 62-Vertical rod, 63-Horizontal rod, 64-Dial indicator, 65-Laser displacement sensor, 66-Electric slider, 71-First guide rail, 72-Second guide rail, 73-T-slot, 91-Outer shell, 91a-Air inlet, 92-Inner ring. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Example 1: This embodiment describes an external pre-adjustment clamping device for thin-walled cylindrical components in aerospace applications, as shown in the reference... Figure 1 As shown, the entire assembly includes a base plate 7, a front female disc fixture 1, a front clamping fixture 2, a tailstock fixture 3, a tail support fixture 4, an auxiliary support fixture 5, a measuring component 6, a rotary joint device 9, and an external rotary motor. The base plate 7 is equipped with a first guide rail 71 and a second guide rail 72. The measuring component 6 is slidably mounted on the first guide rail 71, and the tailstock fixture 3 and auxiliary support fixture 5 are slidably mounted on the second guide rail 72. A T-slot 73 is provided in the middle of the base plate 7 for locking and fixing the corresponding fixtures. The front female disc fixture 1 is fixed to one end of the base plate 7. The front clamping fixture 2 and the front female disc fixture 1 are connected in a detachable positioning manner to clamp the inner hole at the front end of the cylindrical workpiece 8.

[0042] Reference Figure 11 As shown, the front master plate fixture 1 includes a master plate 11 and multiple zero-point seats 12. The zero-point seats 12 are fixedly installed on the front end face of the master plate 11. The zero-point seats 12 adopt pneumatic zero-point positioning clamps, which operate by pneumatic unlocking and spring mechanical locking. (Refer to...) Figures 6 to 10 As shown, the front clamping fixture 2 includes a second base 21, several semi-circular claws 22, a sliding groove positioning block 23, a rear pull rod 24, a threaded block 25, a zero-point pin 26, and a coarse positioning pin 27. The second base 21 has a front end face 21a and a rear end face 21b. The sliding groove positioning block 23 is fixedly installed on the front end face 21a and has a guide groove 23a (see reference). Figure 10Each semicircular claw 22 is slidably assembled in the radial guide groove 23a of the corresponding sliding groove positioning block 23. The rear pull rod 24 is coaxially inserted into the central through hole of the second base 21. Its rear end is provided with an external thread section and is threadedly engaged with the threaded block 25. The rear end face of the rear pull rod 24 is provided with an internal hexagonal operating hole 24b. The outer periphery of the front end of the rear pull rod 24 is a tapered surface 24a, and the inner end of each semicircular claw 22 is provided with an inner inclined surface 22a that matches the tapered surface. When the rear pull rod 24 is rotated to move it axially, the engagement of the tapered surface 24a and the inner inclined surface 22a drives each semicircular claw 22 to expand radially outward synchronously, tightening the inner hole of the front end of the workpiece 8 to achieve self-centering clamping (refer to...). Figure 8 , Figure 9 (Cross-section and internal structure), the semi-circular claw 22 is provided with a limiting hole for placing the limiting block 22b to prevent excessive radial movement of the semi-circular claw 22. The zero-point pin 26 and the coarse positioning pin 27 are both fixedly set on the rear end face 21b (see reference). Figure 7 The zero-point pin 26 corresponds one-to-one with the zero-point seat 12. After the front clamping fixture 2 completes the initial positioning and guidance through the coarse positioning pin 27, it achieves high-precision locking and positioning through the cooperation of the zero-point pin 26 and the zero-point seat 12.

[0043] Reference Figure 2 and Figure 3 As shown, the tail support fixture 4 is used to insert into the inner hole of the tail of the workpiece 8. It includes a first base 41, several semi-circular sliders 42, an adjusting screw 43, and a center block 44. The first base 41 has a radial groove 41a corresponding to the semi-circular sliders 42. The adjusting screw 43 is radially threaded onto the first base 41, and the inner end of the adjusting screw 43 is in transmission engagement with the semi-circular sliders 42. Rotating the adjusting screw 43 can drive the semi-circular sliders 42 to move radially along the radial groove 41a, so that the outer arc surface of the semi-circular sliders 42 fits against the inner wall of the inner hole of the workpiece 8, realizing radially adjustable support. The center block 44 is fixedly installed at the center of the first base 41 near the tailstock fixture 3.

[0044] Reference Figure 4 As shown, the tailstock fixture 3 includes a tailstock 34, a mounting plate 32, and a locking plate 33. The mounting plate 32 is slidably fitted onto the second guide rail 72, and the tailstock 34 is fixedly mounted on the mounting plate 32; see reference. Figure 14 As shown, the locking plate 33 engages with the T-slot 73 via bolts to lock the tailstock 34 to the corresponding position on the second guide rail 72. The tailstock 34 is provided with a center point 31 to press against the center hole of the center block 44, achieving axial and radial positioning of the tail support fixture 4. (Refer to...) Figure 15 As shown, the upper end of the auxiliary support fixture 5 is provided with a bearing 51 that can roll into contact with the outer circle of the workpiece 8, which is used to support the outer wall of the workpiece 8 to enhance the clamping rigidity; the auxiliary support fixture 5 can slide along the second guide rail 72 to adjust the support position to accommodate workpieces 8 of different lengths.

[0045] Reference Figure 5 As shown, the measuring assembly 6 includes a fixed plate 61, a vertical rod 62, a horizontal rod 63, and a dial indicator 64. The fixed plate 61 is slidably mounted on the first guide rail 71. The vertical rod 62 is vertically fixed to the fixed plate 61. The horizontal rod 63 is horizontally mounted on the vertical rod 62 and its position can be adjusted up and down along the vertical rod 62. The dial indicator 64 is mounted on the horizontal rod 63 and can move horizontally along the horizontal rod 63. It is used to detect the outer diameter runout and end face flatness of the workpiece 8 at different positions. (Refer to...) Figure 12 and Figure 13 As shown, the rotary joint device 9 includes a fixed outer shell 91 and an inner ring 92 that can rotate relative to the outer shell 91. The inner ring 92 is connected to the mother disc 11 by a connector. The outer shell 91 is provided with an air inlet 91a connected to an external air passage for supplying compressed air to the zero point seat 12. An external rotary motor is connected to the end of the inner ring 92 to drive the mother disc 11 to rotate, and works with the measuring component 6 to complete the continuous detection of the full circumference outer diameter runout. The front end of the thin-walled cylindrical workpiece 8 is clamped and positioned by the front clamping fixture 2, and the tail end is inserted into the tail support fixture 4 and clamped and centered by the tailstock fixture 3. The auxiliary support fixture 5 supports the outer wall of the workpiece 8, and the whole constitutes a pre-adjusted clamping layout outside the machine tool.

[0046] Example 2: This embodiment presents a high-precision online surface defect detection method based on the aforementioned external pre-adjustment clamping device. This method is implemented through the multi-sensor collaborative measurement system of the measurement component 6. (Refer to...) Figure 16 , Figure 17 As shown, the multi-sensor collaborative measurement system includes three laser displacement sensors 65, an angle encoder that rotates synchronously with the workpiece 8, a data processing module, and electric sliders 66 arranged on the first guide rails 71 on both sides. The electric sliders 66 are connected to an external power supply and drive the measurement components to move axially along the direction of the workpiece 8. In this embodiment, the three laser displacement sensors 65 are evenly arranged at 90° intervals within the upper semicircle of the workpiece 8 (e.g., ...). Figure 17 As shown in the figure, they are located at 0°, 90° and 180° circumferential positions with the center of the workpiece cross section as the reference, respectively, to cover the upper half of the outer surface area of ​​the workpiece; the optical axes of each sensor point to the workpiece rotation axis.

[0047] Before the test begins, adjust each laser displacement sensor 65 so that its optical axis is focused on the outer surface of the workpiece, and adjust the sensor range to cover the range of changes in the outer diameter of the workpiece. Start the external rotary motor to drive the mother disk 11 to rotate, and the workpiece 8 rotates synchronously. At the same time, the rotary joint device 9 ensures the stability of the air path of the zero point seat 12 to prevent the workpiece from loosening during the test.

[0048] After the detection begins, the data processing module controls the measuring component 6 to perform axial step scanning along the first guide rail 71 with a preset step size Δz (Δz can be set according to the actual project; in this embodiment, Δz = 5mm). At each axial section position Z... j At (j=1, 2, ..., N), the angle θ of the workpiece 8 is as follows. i (i=1,2,…,M), synchronously acquire the displacement measurement values ​​d(θ) output by three laser displacement sensors (65). i Z j The corresponding angle value θ output by the angle encoder. i This forms a circumferential displacement sequence for each cross-section. Since the three sensors are distributed at 90° intervals within the upper semicircle, each sensor sequentially acquires the surface distance data of the corresponding arc segment with each rotation of the workpiece 8. The combination of these three data points reconstructs the complete contour information of the entire circumference. After single-section acquisition, the measuring component 6 is moved to the next axial position by the electric slider 66 until the entire length of the workpiece is covered. In this step, the rotation speed of the workpiece 8 must be very slow to prevent runout errors. At the same axial cross-section, the three sets of laser displacement sensors 65 obtain three complete circumferential displacement sequences, denoted as d1(θ). i Z j ), d2(θ i Z j ) and d3(θ i Z j ).

[0049] Due to manufacturing and assembly tolerances during the mechanical installation of the three sensors, there are slight fixed phase deviations between their actual circumferential installation angles and the theoretical values ​​(0°, 90°, 180°) (measured in this embodiment to be approximately +0.05°, -0.15°, and +0.10° respectively). This deviation causes the same physical defect to be marked at different rotation angles in the displacement sequences recorded by the three sensors. Therefore, before formal defect identification, the data processing module first performs phase synchronization correction on the angle sequences of each sensor.

[0050] Using the first sensor as a reference, d2(θ,Z) is intercepted respectively. j ) and d1(θ,Z j ), d3(θ,Z j ) and d1(θ,Z j For the complete circumferential profile waveforms on the same cross section, the relative phase offset Δφ between the two sets of waveforms is calculated using a cross-correlation algorithm. 21 and Δφ 31Specifically, by iterating through the angular translation δ, the cross-correlation coefficient of the two displacement sequences within the overlapping angle range is calculated, and the translation δ corresponding to the maximum value of the cross-correlation coefficient is taken as the measured phase deviation of the sensor. The arithmetic mean of the phase deviation values ​​measured across all cross sections along the entire axis is taken to obtain the stable and constant system phase deviation compensation for each sensor. Subsequently, the displacement sequences of sensor 2 and sensor 3 are translated in opposite directions along the angle axis according to the corresponding deviation compensation, so that the angular zero points of the three sets of circumferential displacement sequences are completely unified to the same physical reference. Simultaneously, to eliminate random errors introduced by a single comparison, the average value of the phase deviations obtained from pairwise comparisons of the three sets of sensors is taken as the final correction amount to ensure the global consistency of the angular coordinate system. After completing the angle synchronization, the data processing module performs calculations for each axial cross section Z. j The three aligned circumferential displacement sequences are fused to form a single and complete circumferential displacement sequence d(θ) for this cross section. i Z j And perform the following defect identification steps: The first step is to perform a cross-section Z on each axial section. j Displacement sequence d(θ) along the circumferential direction of the workpiece i Z j Perform point-by-point difference comparisons and calculate the first-order forward difference value Δd between each adjacent measuring point. i =d(θ {i+1} )-d(θ i Identify the location θ of the measuring point where the sign of the difference value reverses. k That is, satisfying (Δd) {k-1} >0 and Δd k <0) or (Δd) {k-1} <0 and Δd k Points with values ​​greater than 0 are taken as circumferential extreme points.

[0051] The second step is to filter the circumferential extreme points. Calculate the current cross-section Z. j The average displacement μ j and standard deviation σ j Extract the amplitude deviation from the cross-sectional mean μ. j More than three standard deviations 3σ j The extreme points are used as candidate anomaly points, and the above operation is repeated for all axial sections to obtain a set of candidate anomaly points on the entire workpiece surface.

[0052] The third step is to process each candidate outlier point P(θ) p Z p ), and capture a circumferential local window W centered on it. θ ={θ| θp -w θ ≤θ≤θ p +w θ} and axial local window W z ={Z|Z p -w z ≤Z≤Z p +w z}, where w θ and w z To preset the window half-width, w θ Set an appropriate value based on the actual outer diameter of workpiece 8, w z The appropriate value is set based on the actual length of workpiece 8; in this embodiment, it is assumed to be w. θ =10°, w z =15mm. Calculate the circumferential effective energy E based on the displacement data within the window. θ and axial effective energy E z .

[0053] ; Among them, L θ ω is the number of sampling points within the circumferential window. q These are weighting coefficients (those closer to the center point have higher weights). This is an indicator function, taking a value of 1 only when both an ascending and descending displacement segment exist within the window; otherwise, it is 0. It should be noted that the circumferential effective energy E... θ In the calculation formula, Used to quantify the degree of displacement change between adjacent sampling points within a window, its value directly reflects the steepness of the local surface contour slope; weighting coefficient ω q A distribution pattern with values ​​increasing closer to the window center is adopted to enhance the contribution weight of the central region of the window and reduce noise interference in the edge region; indicator function The value is set to 1 only when the displacement sequence within the window simultaneously contains both rising and falling segments; otherwise, it is set to 0. This eliminates monotonic variations caused by overall workpiece tilt or installation eccentricity, ensuring that the effective energy is calculated only for isolated defects with complete pulse patterns. Only when Eθ exceeds a preset threshold is the candidate point determined to have significant defect morphology characteristics in the circumferential direction.

[0054] The axial effective energy E is calculated in the same way. z .

[0055] ; Among them, E z L represents the effective energy value of the candidate defect point in the axial direction. z The total number of sampling points within the axial local window This is an indicator function that takes a value of 1 only when the displacement sequence within the window simultaneously contains both rising and falling segments; otherwise, it takes a value of 0. ω q These are weighting coefficients (those closer to the center point have higher weights).

[0056] If E θ and E z All exceeded the preset threshold E th (This embodiment assumes E) th =0.005mm 2 (This value can be set based on the accuracy of the laser displacement sensor 65 and the known size of artificial defects on the standard sample), then the candidate anomaly point is determined to be a real defect point.

[0057] The fourth step is to determine the defect type based on the sign combination of the rising and falling slopes within the window for the location identified as a true defect point. The average slope of the rising segment is defined as k. u >0, the average slope of the descending segment is k d If k < 0, it is a convex point (i.e., a protruding defect on the outer surface); if k u <0 and k d If the value is greater than 0, it indicates a depression (i.e., a pit defect on the outer surface).

[0058] The fifth step involves cross-validating the circumferential and axial detection results. For each genuine defect point, it is checked whether it is detected in both the circumferential and axial cross-sectional identification results; only defect points identified simultaneously in both directions are retained, while false defect points detected in one direction are eliminated. Furthermore, since each of the three sensors independently measures the complete circumferential profile, if a defect point is identified only in the data from a single sensor while the other two sensors show no response at the corresponding position, it is determined to be a false signal introduced by individual sensor noise and is eliminated. Only defect points repeatedly identified in the data from at least two sensors are retained, thereby utilizing multi-sensor redundancy information to further reduce the false detection rate.

[0059] Finally, output the axial position Z of each defect point. p Circumferential angle θ p and radial amplitude A p (Measured by the magnitude of the deviation of the displacement value at that point relative to the mean value of the cross section). Simultaneously, a standard template library is established for qualified workpieces. In this embodiment, the test results are compared with the template library to eliminate systematic deviations caused by the roundness error of the workpiece itself, and only defect information exceeding a preset threshold due to deviation from the template is output.

[0060] Example 3: This embodiment presents a method for precise defect localization based on the aforementioned multi-sensor collaborative measurement system. Building upon the cross-validation confirmation described in Embodiment 2, it reconstructs the three-dimensional spatial position and defines the influence range of the actual defect point with sub-sampling level precision. The data processing module performs arcuate curve fitting in both the circumferential and axial directions for each cross-validated defect point. Using a confirmed actual defect point P0 (coarsely located axial position Z),...p0 Circumferential angle θ p0 Radial amplitude A p0 For example, ( ).

[0061] Circumferential fitting: A circumferential window Wθ'={θ|θ' is truncated with P0 as the center. p0 -15°≤θ≤θ p0 +15°}, using an arc curve to fit the displacement data within the window: ; The Levenburg-Marquardt algorithm is used to iteratively solve for the amplitude parameter hθ, the circumferential precise center μθ, and the circumferential influence width σ. θ and circumferential baseline b θ This minimizes the sum of squared residuals. The initial value for the iteration is set to h. θ (0)=A p0 μ θ (0)=θ p0 , σ θ (0) = 3°. It should be noted that h θ (0)=A p0 The amplitude selected through 3σ statistics in Example 2 is a reasonable estimate of the true amplitude and is directly used as the initial value that is closest to the true value. μ θ (0)=θ p0 Since the coarse positioning center is already at the extreme point, using it as the initial value is most reasonable. Subsequent adjustments only require fine-tuning. σ θ (0) = 3° is about 1 / 3 of the half width of the window, which is a conservative and reasonable initial estimate; and the subsequent algorithm will automatically adjust to the optimal value, so the initial value only needs to be within the correct order of magnitude.

[0062] Axial fitting: An axial window Wz'={Z|Z centered at P0 is selected. p0 -20mm≤Z≤Z p0 +20mm}, using the same type of arc curve to fit the axial displacement sequence within the window: ; Similarly, the axial magnitude h is solved iteratively using the Levenberg-Marquardt algorithm. z , Axial precise center μ z Axial influence on width σ z and axial baseline b z The initial value for the iteration is set to h. z (0)=A p0 μ z (0)=Z p0 , σ z (0) = 5mm μ obtained from fitting θ and μ zas the precise three-dimensional central coordinate of the defect point; taking h θ and h z as the mean value to be the final maximum amplitude; using 3σ θ and 3σ z to define their spatial influence ranges in the circumferential direction and the axial direction respectively. During the fitting process, if the coefficient of determination R 2 <0.85, a warning mark is output for manual review, otherwise the precise position and influence range are directly output.

[0063] Repeat the above circumferential and axial fitting process for all real defect points to obtain the precise three-dimensional coordinates and two-way influence range of each defect point on the surface of the entire workpiece. When the coarsely positioned distance between two defect points is less than the sum of the sizes of the fitting windows (i.e., |θ p1 -θ p2 |<2Wθ' or |Z p1 -Z p2 |<2Wz'), the fitting windows of the two overlap. To avoid mutual signal interference, the data processing module automatically reduces the half-width of the fitting window of each of the two defect points to half of the distance between the two, so that each window is demarcated at the middle position between the adjacent defects, ensuring that the data taken for respective fitting are independent and do not contain each other's signals. This is recorded, and manual verification of the actual defect size is required later.

[0064] Embodiment 4: This embodiment is a defect morphology classification and workpiece state determination method based on the aforementioned precise positioning result. For each defect point, the data processing module extracts its axial influence range σ z and circumferential influence range σ θ , and calculates the ratio R=σ z / σ θ : When R≤0.5, it is determined as a point-shaped defect. The influence ranges of this type of defect in the axial direction and the circumferential direction are basically equivalent with a relatively small ratio, and the morphology is approximately an isolated point, typically such as local pores in the material, isolated pits or tiny protrusions. Point-shaped defects are usually caused by internal material defects or local collisions, and their stress concentration effect is relatively limited, but they still need to be strictly controlled for aerospace parts with high fatigue requirements.

[0065] When 0.5<R≤2, it is determined as an isometric defect. This type of defect has a similar extension degree in both the axial direction and the circumferential direction, and its morphology is approximately a circular or square area, typically such as a local scratch area with a very small area, a scratch patch or local material accumulation. The isometric defect has a small area and is easy to locate and locally repair in subsequent reprocessing.

[0066] When R>2, it is determined as a strip-shaped defect. This type of defect extends significantly more in the axial direction than in the circumferential direction, presents an elongated shape, and typically includes machining tool marks, axial scratches, galling, or strip-shaped material accumulation. Strip-shaped defects are often distributed along the direction of machining texture, with a large influence range, a high stress concentration coefficient, and are prone to penetrating the local load-bearing cross-section of thin-walled parts, making them the defect type that requires the most critical control for aerospace thin-walled cylindrical parts.

[0067] After the classification is completed, the state of the workpiece is graded and determined according to the maximum amplitude A of each defect point. Let the first threshold T1=0.01mm and the second threshold T2=0.05mm, wherein the first threshold and the second threshold can be set according to actual working conditions. If all A<T1, the workpiece is judged as a qualified product; if any T1≤A<T2, the workpiece is judged as a repairable product, and the three-dimensional coordinates, category and influence range of the defect point are output for subsequent re-machining; if any A≥T2, the workpiece is judged as a scrap product. The data processing module generates a comprehensive inspection report, which includes the total number of defects, the quantity and proportion of each category, the information of each defect point and the overall conclusion of the workpiece, and maps the defect points marked with different colors by category to the surface of the three-dimensional model of the workpiece. This embodiment realizes automatic and standardized evaluation of the surface quality of aerospace thin-walled cylindrical parts, provides accurate repair guidance for repairable products, and reduces the scrap rate and manufacturing cost.

[0068] The above-described embodiments and / or implementations are only used to illustrate the preferred embodiments and / or implementations for realizing the technology of the present invention, and do not impose any form of limitation on the implementations of the technology of the present invention. Any person skilled in the art may make some modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but such modifications shall still be regarded as technologies or embodiments substantially identical to the present invention. Specific examples are used herein to illustrate the principles and implementations of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. The foregoing is only the preferred embodiment of the present application, and it should be noted that due to the limited nature of textual expression, there are objectively infinite specific structures. For those of ordinary skill in the art, several improvements, modifications or variations may be made without departing from the principles of the present application, and the above technical features may be combined in an appropriate manner; these improvements, modifications, variations or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvements, shall all be regarded as falling within the protection scope of the present application.

Claims

1. An external pre-adjustment clamping device for thin-walled cylindrical parts of aircraft, comprising a base plate (7), a front master plate fixture (1), a front clamping fixture (2), a tail seat fixture (3), a tail support fixture (4), an auxiliary support fixture (5), and a measuring component (6). The base plate (7) is provided with a first guide rail (71) and a second guide rail (72). The measuring component (6) is slidably mounted on the first guide rail (71), and the tailstock fixture (3) and the auxiliary support fixture (5) are slidably mounted on the second guide rail (72). The front mother plate fixture (1) is fixed to one end of the base plate (7), and the front clamping fixture (2) is detachably positioned therewith. Tail support fixture (4) is used to insert into the inner hole of the tail of the workpiece (8), and it is provided with a radially adjustable support structure to fit the inner hole wall of the workpiece (8). The tailstock fixture (3) moves and locks along the second guide rail (72). It is equipped with a top (31) for pressing against the center of the tail support fixture (4) to achieve axial and radial positioning of the tail support fixture (4). The measuring component (6) moves along the first guide rail (71) to any axial position of the workpiece (8).

2. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 1, characterized in that, The tail support fixture (4) includes a first base (41), several semi-circular sliders (42), an adjusting screw (43), and a center block (44). The first base (41) has a radial groove (41a) corresponding to the semicircular slider (42). The adjusting screw (43) is connected to the first base (41) radially. The inner end of the adjusting screw (43) is in transmission cooperation with the semicircular slider (42). Rotating the adjusting screw (43) can drive the semicircular slider (42) to move radially along the radial groove (41a), so that the outer arc surface of the semicircular slider (42) fits against the inner wall of the inner hole of the workpiece (8). The tip block (44) is fixedly installed at the center of the first base (41) near the tailstock tool (3), and the tip (31) can be pressed against the center hole of the tip block (44).

3. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 1, characterized in that, The front clamping fixture (2) includes a second base (21), several semi-circular claws (22), a sliding groove positioning block (23), a rear pull rod (24), a threaded block (25), a zero point pin (26), and a coarse positioning pin (27). The second substrate (21) has a front end face (21a) and a rear end face (21b). The sliding positioning block (23) is fixedly installed on the front end face (21a). The sliding positioning block (23) is provided with a guide groove (23a). Each semi-circular claw (22) is slidably assembled in the radial guide groove (23a) of the corresponding sliding positioning block (23). The rear pull rod (24) is coaxially inserted into the central through hole of the second base (21). The outer periphery of the front end of the rear pull rod (24) is a tapered surface (24a), and the inner end of each semi-circular claw (22) is provided with an inner inclined surface (22a) that matches the tapered surface. The rear end of the rear pull rod (24) is provided with an external thread section and is threadedly engaged with the threaded block (25). The rear end face of the rear pull rod (24) is provided with an internal hexagonal operating hole (24b). When the pull rod (24) is rotated to make it move backward in the axial direction, the semicircular claws (22) are driven to expand outward in the radial direction through the cooperation of the tapered surface (24a) and the inner inclined surface (22a), which tightens the inner hole at the front end of the workpiece (8) to achieve self-centering clamping. The semicircular claws (22) are provided with limiting holes for placing limiting blocks (22b). The zero-point pin (26) and the coarse positioning pin (27) are both fixedly set on the rear end face (21b) for positioning and cooperating with the front mother plate tooling (1).

4. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 3, characterized in that, The front master plate fixture (1) includes a master plate (11) and several zero point seats (12). The zero point seats (12) are fixedly installed on the front end face of the master plate (11). The zero point seats (12) correspond one-to-one with the zero point pins (26) to realize the rapid positioning and pneumatic locking of the front clamping fixture (2).

5. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 4, characterized in that, It also includes a rotary joint device (9), which is adapted to an external rotary motor; The rotary joint device (9) includes a fixed outer shell (91) and an inner ring (92) that can rotate relative to the outer shell (91). The inner ring (92) is connected to the mother plate (11) by a connector. The outer shell (91) is provided with an air inlet (91a) connected to an external air passage for supplying compressed air to the zero point seat (12). The external rotary motor is connected to the end of the inner ring (92) and is used to drive the inner ring (92) to rotate.

6. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 1, characterized in that, The tailstock fixture (3) includes a tailstock (34), a mounting plate (32), and a locking plate (33); The mounting plate (32) is slidably fitted on the second guide rail (72), and the tailstock (34) is fixedly installed on the mounting plate (32); the base plate (7) has a T-slot (73), and the locking plate (33) is fitted with the T-slot (73) by bolts to lock the tailstock (34) at the corresponding position on the second guide rail (72).

7. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 1, characterized in that, The measuring component (6) includes a fixed plate (61), a vertical rod (62), a horizontal rod (63), and a dial indicator (64). The fixed plate (61) is slidably mounted on the first guide rail (71), the vertical rod (62) is vertically fixed on the fixed plate, and the horizontal rod (63) is horizontally mounted on the vertical rod (62) and can be adjusted up and down along the vertical rod; the dial indicator (64) is mounted on the horizontal rod (63) and can be moved horizontally along the horizontal rod (63) to detect the runout of the outer circle and the flatness of the end face of the workpiece (8) at different positions.

8. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 1, characterized in that, The measuring component (6) includes a plurality of laser displacement sensors (65), an angle encoder, an electric slider (66), and a data processing module arranged circumferentially along the workpiece (8); The data processing module controls the electric slider (66) to drive the measuring component (6) to scan axially along the first guide rail (71) and collect the circumferential displacement sequence of each laser displacement sensor (65) with the rotation angle of the workpiece (8) at each axial section. The data processing module performs differential comparisons on the displacement sequence along the circumferential direction to identify extreme points, and selects extreme points whose amplitude deviates from the mean of the cross section by more than a set number of standard deviations as candidate outliers.

9. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 8, characterized in that, The data processing module extracts displacement data within a local window for each candidate anomaly point, and makes a comprehensive judgment based on the displacement change amplitude and morphological characteristics within the local area. If the preset defect judgment conditions are met, it is confirmed as a real defect point, and the concavity / convexity type of the defect is determined based on the morphological characteristics. The data processing module also cross-validates the circumferential and axial detection results, retains only the defect points identified in both directions, and outputs the axial position, circumferential angle, and radial amplitude of each defect point.

10. The external pre-adjustment clamping device for thin-walled cylindrical parts in aerospace as described in claim 9, characterized in that, The data processing module extracts local windows centered on the cross-validated defect points in both the circumferential and axial directions, and uses a predetermined fitting function to fit the displacement data within each window. Through iterative optimization, it determines the defect center position, maximum amplitude, and influence width parameters that make the fitting residuals meet the convergence conditions. The center position obtained by fitting is used as the precise coordinate of the defect point, and the spatial influence range of the defect point is defined by the influence width of a preset multiple. The circumferential and axial fitting results are combined to obtain the precise three-dimensional center coordinates of each defect point and its bidirectional influence range in both the circumferential and axial directions.

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