Active control device and method for elastic deformation of thin-walled ring parts

Abstract

To solve the technical problem that the existing mechanical auxiliary support cannot realize the elastic deformation control in the milling process of the thin-walled annular part, the present application provides a thin-walled annular part processing elastic deformation active control device and method. The present application builds a clamping module to realize the positioning and clamping of the thin-walled annular part; designs an active support module to apply controllable support force to the inner surface of the thin-walled annular part through multiple independent and support force controllable support devices, providing a basis for the active control of the elastic deformation in the milling process; and combines the deformation monitoring module and the regulation and control module to realize the active control of the elastic deformation in the processing of the thin-walled annular part for the first time, solving the elastic deformation problem caused by the introduction of the milling force in the processing of such thin-walled annular parts.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mechanical processing and relates to a thin-walled annular part processing elastic deformation active control device and method. BACKGROUND

[0002] Thin-walled annular parts are widely used in aircrafts, such as aero-engine casings and missile control shell housings, due to their light weight and compact structure. The manufacturing quality of such thin-walled annular parts is crucial for the long-term stable service performance of aircrafts in complex extreme working environments such as high temperature, high pressure and high speed. Therefore, the processing quality of the thin-walled annular parts needs to be strictly controlled. However, the thin-walled annular parts have weak rigidity, low strength and difficult-to-machine material characteristics. Under the action of cutting force, different degrees of deformation will occur during the machining process, thereby affecting the processing quality.

[0003] In order to improve the processing quality of thin-walled annular parts, the deformation during processing needs to be controlled. However, most existing deformation control methods consider less time-varying influencing factors during workpiece processing. Usually, a fixed size of supporting force is applied to the workpiece in advance through mechanical structure, which is difficult to achieve active control of elastic deformation during processing. Therefore, the effect of improving the processing quality of annular thin-walled parts is not ideal.

[0004] The patent document with publication number CN115922226A discloses a self-adaptive machining tooling for thin-walled cylinders and a self-adaptive machining method. In this scheme, the radial support device and the radial adsorption device are driven according to the pressure signal to adaptively adjust the machining deformation of the part. This scheme has a certain inhibitory effect on elastic deformation during processing. However, for milling processing, factors such as weak rigidity of the workpiece, non-uniformity of the material and tool wear will cause strong time-varying of the cutting force. This scheme only adjusts the deformation that occurs in real time based on the pressure signal, which has certain defects: on the one hand, the response of the radial support device has a lag, and there may be a certain amount of error that is not compensated in time; on the other hand, as the process progresses, these un-timely compensated error amounts will gradually accumulate, resulting in ineffective control of the elastic deformation of the workpiece during processing, and ultimately producing an overage. SUMMARY

[0005] To solve the problem that the existing deformation control scheme cannot compensate for the deformation in time and cannot effectively control the elastic deformation during processing, the present application provides a thin-walled annular part processing elastic deformation active control device and method.

[0006] To solve the above technical problems, the technical scheme of the present application is as follows:

[0007] The device is characterized in that it comprises a clamping module, an active support module, a deformation monitoring module and a control module.

[0008] The clamping module is used for circumferential positioning and axial clamping of the thin-walled annular workpiece.

[0009] The active support module is used for providing adjustable, multiple independent and equal radial support forces to the inner profile of the thin-walled annular workpiece; the active support module has a support force detection function and can send the support force provided by the active support module to the control module.

[0010] The deformation monitoring module is used for monitoring the elastic deformation of the thin-walled annular workpiece during the machining process.

[0011] The control module is used for controlling the operation of the active support module and the deformation monitoring module; the control module also has a preset elastic deformation prediction model and a support force control curve of each machining node.

[0012] The control module adjusts the support force provided by the active support module based on the support force data detected by the active support module and the support force control curve in the process; the control module can also process the support force data detected by the active support module and the elastic deformation data detected by the deformation monitoring module before the start of the next process, obtain the actual deformation field of the thin-walled annular workpiece in the previous process, compare the actual deformation field with the deformation field of the previous process predicted by the elastic deformation prediction model to obtain the support force compensation amount of the next process, and send a support force control instruction to the active support module based on the support force compensation amount and the support force control curve before the start of the next process, so as to realize the support force control between processes.

[0013] Further, the clamping module comprises a clamping sub-module and a positioning sub-module; the clamping sub-module comprises a clamping bottom plate, a double-head flange support column and a clamping cover plate connected in sequence from bottom to top, and the thin-walled annular workpiece is clamped by the clamping bottom plate and the clamping cover plate; the positioning sub-module comprises at least three positioning rings arranged on the clamping bottom plate and distributed along the same circumference, and the outer sidewall of the positioning ring is matched with the inner wall profile of the thin-walled annular workpiece.

[0014] Further, the upper surface of the clamping bottom plate is provided with a plurality of arc-shaped holes, a plurality of strip-shaped grooves and a plurality of mounting holes; the arc-shaped holes and the strip-shaped grooves are used for discharging cooling liquid during the machining process; the mounting holes are used for mounting the positioning sub-module; the mounting holes have multiple groups, and each group is distributed on a circumference with different sizes, so as to adjust the positioning size of the positioning sub-module.

[0015] Further, the active supporting module comprises driving devices arranged on the clamping bottom plate and executing devices with supporting force detection function; the executing devices are m in number and are uniformly distributed along the same circumference, and can be independently moved along the radial direction under the driving of the driving devices to press against the inner wall of the thin-walled annular part to support it; the driving devices are connected with the control module and are controlled by the control module; m≥3.

[0016] The executing devices are pneumatic executing devices, electric executing devices or hydraulic executing devices, and correspondingly, the driving devices are pneumatic driving devices, electric driving devices or hydraulic driving devices.

[0017] Further, the executing devices are pneumatic executing devices, which comprise a supporting base and m supporting devices; the supporting legs of the supporting base are fixedly installed on the clamping bottom plate, and the table top of the supporting base is used for supporting and installing the m supporting devices; a single supporting device comprises a cylinder, a sensor connecting plate, a pressure sensor, a supporting head connecting plate and an inner profile supporting head connected in sequence; the cylinder is installed on the table top of the supporting base, and the sensor connecting plate is fixedly connected with the push rod of the cylinder; the sensor connecting plate and the supporting head connecting plate are connected through clamping bolts;

[0018] The driving devices are pneumatic driving devices, which comprise m driving groups arranged on the clamping bottom plate; a single driving group comprises an electromagnetic valve, an electric proportional valve and a signal converter arranged on the clamping bottom plate; the electromagnetic valve and the electric proportional valve are connected with the cylinder, the electric proportional valve is used for adjusting the gas pressure entering the cylinder to a specified gas pressure, and the electromagnetic valve is used for transmitting the gas at the specified gas pressure to the cylinder; the signal converter is connected with the pressure sensor and is used for converting the electric signal output by the pressure sensor into a signal recognizable by the control module.

[0019] Further, the active supporting module is one or more; when there are multiple active supporting modules, they are arranged in sequence along the axial direction and are used in combination to support different axial regions of the thin-walled annular part.

[0020] Further, the deformation monitoring module comprises m deformation monitoring devices arranged on the table top of the supporting base; the m deformation monitoring devices are uniformly distributed along the circumferential direction, and one deformation monitoring device is arranged between every two supporting devices; a single deformation monitoring device comprises a displacement sensor and a preamplifier; the displacement sensor is installed on the table top of the supporting base through a displacement sensor mounting plate, and is used for detecting the elastic deformation of the inner profile of the thin-walled annular part; the preamplifier is used for providing the power required by the displacement sensor and amplifying, detecting and filtering the signal output by the displacement sensor.

[0021] Further, the control module comprises an industrial computer, a PLC, a digital-analog conversion module, a data acquisition module, a power supply and an air compressor; the industrial computer is pre-stored with the elastic deformation prediction model; the PLC is pre-stored with the support force control curve of each processing node, and is provided with a corresponding relationship between a voltage signal and an air pressure value;

[0022] Before the processing procedure starts, the industrial computer sends a first control instruction to the PLC, the PLC cooperates with the digital-analog conversion module to send corresponding analog signals to all electrical proportional valves of the pneumatic driving device in the active support module according to the received first control instruction and based on the support force control curve, so as to realize setting of an initial air source air pressure; subsequently, the PLC sends digital signals to all electromagnetic valves of the pneumatic driving device in the active support module through an IO port to control synchronous extension and retraction of all cylinders of the pneumatic driving device in the active support module, so as to realize setting of an initial state of the active support module;

[0023] Then, the PLC sends a first request instruction to all pressure sensors of the pneumatic driving device in the active support module, the data acquisition module reads monitoring values of the pressure sensors in the active support module to the PLC, and the PLC compares the support force monitoring values with the support force setting values; if the values are inconsistent and need to be adjusted to the setting values, the PLC cooperates with the digital-analog conversion module to perform feedback adjustment by using a PID algorithm until the active support module provides the required support force to the thin-walled annular workpiece, and then a normal milling procedure is started;

[0024] During the processing, the industrial computer sends a second request instruction to the displacement sensors in the deformation monitoring module, the data acquisition module reads monitoring values of all displacement sensors to the industrial computer, and the industrial computer performs data fitting to obtain an actual deformation field of an inner surface of the thin-walled annular workpiece, and then compares the actual deformation field with a workpiece deformation field predicted by the elastic deformation prediction model, calculates a required support force compensation amount in the next processing procedure by using Hooke's law, and all support devices correspond to the same support force compensation amount;

[0025] During the processing procedure, the industrial computer determines the required support force according to the support force compensation amount of the next processing procedure obtained in the foregoing and transmits the support force to the PLC, and then the PLC converts the support force-air pressure value to determine a required air pressure value after support force compensation, the PLC sends analog signals corresponding to the compensated air pressure value to all electrical proportional valves of the pneumatic driving device in the active support module through the digital-analog conversion module, so as to realize adaptive adjustment of the support force.

[0026] The application further provides a thin-walled annular workpiece processing elastic deformation active control method, which is characterized in that the method comprises the following steps:

[0027] Step 1: Obtain the deformation field and stiffness field after each process, as well as the support force control curve within each process;

[0028] Step 1.1 Create a CAD model after each process and import it into the finite element simulation software;

[0029] Step 1.2: Determine the range of fixed support forces corresponding to each process based on the experimentally calibrated milling forces within the process.

[0030] Step 1.3: For each process, within the range of the corresponding fixed support force, select k fixed support force values ​​according to the set step size. Based on the CAD model after the process is completed and through finite element simulation, establish a set of first elastic deformation prediction models for it. This set of first elastic deformation prediction models includes k models, each corresponding to the k fixed support force values. For s processes, s sets of first elastic deformation prediction models need to be constructed. After the model is established, set the model parameters, including milling force, support force, boundary conditions, material properties, and contact conditions. The milling force is obtained by experimental calibration, and the support force is the k fixed support force values ​​selected according to the set step size.

[0031] Step 1.4: For each process, set a milling path, which includes n processing nodes. After simulation, k sets of elastic deformation data can be obtained for each process's n processing nodes.

[0032] Step 1.5: For each process, construct a data set using k sets of elastic deformation data and corresponding fixed support force values ​​for each processing node in the process. Use numerical fitting to solve the functional relationship between elastic deformation and support force at each processing node in the process. Set constraints to constrain the elastic deformation within the design tolerance range, and solve this functional relationship to obtain the target support force for each processing node in the process.

[0033] Step 1.6: For each process, perform function interpolation and fitting on the target support force of each processing node in the process to obtain the support force control curve of each processing node in the process; a total of s support force control curves are obtained for s processes;

[0034] Step 1.7: Build a second elastic deformation prediction model for each process through finite element simulation and set the parameters of the elastic deformation prediction model, including milling force, support force, boundary conditions, material properties, and contact conditions. The milling force is still the milling force calibrated by the experiment, and the support force is determined according to the support force control curve of each processing node in the process. A total of s second elastic deformation prediction models are required for s processes.

[0035] Step 1.8. For each process, a milling path including n machining nodes is first set, and after simulation, the elastic deformation data of the n machining nodes in the process after machining are obtained, each machining node corresponding to an elastic deformation data; the elastic deformation data are arranged according to the positions of the machining nodes, and thus the deformation field of the workpiece after the process is obtained;

[0036] Step 1.9. The stiffness field of the workpiece is calculated according to the deformation field of the workpiece after each process;

[0037] Step 2. In the current machining process, the support force provided by all the support devices for supporting the inner wall of the thin-walled annular workpiece is adjusted by using the closed-loop feedback control method based on the support force control curve of each machining node in the process obtained in step 1.6;

[0038] Step 3. After the current process is completed, the support force compensation amount of the next process is obtained;

[0039] Step 3.1. z characteristic points are selected on the rigid weak area of the inner surface of the thin-walled annular workpiece, and elastic deformation detection devices are arranged at the characteristic points, and the measured data of the elastic deformation at the z characteristic points are obtained by using the elastic deformation detection devices;

[0040] Step 3.2. z elastic deformation extraction points corresponding to the z characteristic points are set on the second elastic deformation prediction model, and after simulation, the prediction data of the elastic deformation at the z characteristic points are obtained;

[0041] Step 3.3. After the current process is completed, the elastic deformation prediction error is obtained by comparing the measured data and the prediction data of the elastic deformation at the z characteristic points, and then the support force compensation amount is obtained, and the support force preset values of each machining node in the next process are compensated by using the support force compensation amount, wherein the support force preset values are determined according to the support force control curve;

[0042] Step 4. The support force compensation amount of the next process determined in step 3 and the support force preset values of each machining node in the next process on the support force control curve are superimposed respectively, and thus the actual support force required by each machining node in the next process is obtained, which is used as the support force provided by all the support devices for supporting the inner wall of the thin-walled annular workpiece;

[0043] Step 5. Steps 2-4 are executed in a loop until all processes are completed.

[0044] Further, the method for obtaining the support force compensation amount is as follows:

[0045] In any current process, the actual cutting depth of the workpiece can be expressed as de,i=dp,i+ei, wherein, d e,iand dp,i are the actual and designed depth of cut in the process, and ei is the machining error of each machining position.

[0046] The support force compensation amount is ΔF s = K G · e i , wherein K G is the workpiece stiffness field obtained by using the second elastic deformation prediction model in step 1.

[0047] The beneficial effects of the present application are as follows:

[0048] 1. The present application uses a clamping module to position and clamp the thin-walled annular part, uses an active support module to apply the required support force to the thin-walled annular part, uses a deformation monitoring module to monitor the actual deformation of the thin-walled annular part during machining, and uses a control module to adjust the support force applied by the active support module to the thin-walled annular part in the next process according to the actual deformation and the predicted machining deformation, thereby achieving the application of the required support force to the weak rigidity area of the thin-walled annular part at different machining stages, effectively improving the elastic deformation problem during the machining of the thin-walled annular part, and improving the machining quality.

[0049] 2. The present application can pre-establish a support force control curve according to the characteristics of the thin-walled annular part, and through the use of a single active support module or the combined use of multiple active support modules, the controllable inner surface support of the support force can be achieved. In addition, in view of the fluctuation of cutting force, the PLC reads the pressure sensor signal in real time and controls the active support module to adjust the support force in real time.

[0050] 3. The present application monitors the deformation of the workpiece during machining in real time through the deformation monitoring module, obtains the deformation field of the thin-walled annular part in the previous process through the joint control module between processes, provides a reference for the support force provided by each support device in the active support module in the next process, compensates for the error accumulation caused by time-varying factors during the machining process, and avoids the workpiece out-of-tolerance caused by error accumulation.

[0051] 4. The present application realizes the deformation control of the thin-walled annular part in the whole process through the combined use of the in-process support force control and the inter-process support force compensation, and does not need to remove the clamping or manually adjust the transverse support device during use, thereby reducing the error introduced by human factors. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a structural schematic diagram of the thin-walled annular part machining elastic deformation active control device of the present application.

[0053] Figure 2 It is a structural schematic diagram of the clamping sub-module in the present application.

[0054] Figure 3 Structure diagram of the positioning sub-module in the application.

[0055] Figure 4 Structure diagram of the active support module in the application.

[0056] Figure 5 Structure diagram of the execution device in the application.

[0057] Figure 6 Structure diagram of the support device in the application.

[0058] Figure 7 Structure diagram of the driving device in the application.

[0059] Figure 8 Structure diagram of the deformation monitoring module in the application.

[0060] Figure 9 Structure diagram of a certain thin-walled ring-shaped part.

[0061] Figure 10 Structure diagram of the state of clamping and supporting the thin-walled ring-shaped part by using the application.

[0062] Figure 11 Usage flow diagram of the thin-walled ring-shaped part machining elastic deformation active control device in the application.

[0063] Figure 12 Diagram of the signal transmission mode involved in the thin-walled ring-shaped part machining elastic deformation active control device in the application.

[0064] Figure 13 Example of the active support module in the application being multiple and used in combination.

[0065] Explanation of reference signs:

[0066] 100-clamping module; 101-clamping sub-module; 1011-clamping bottom plate; 1012-double-head flange support column; 1013-clamping cover plate; 1014-bolt set; 102-positioning sub-module; 1021-first positioning ring; 1022-second positioning ring; 1023-third positioning ring; 1024-fourth positioning ring;

[0067] 200 - Active support module; 201 - Pneumatic actuator; 2011 - Support base; 2012 - First support device; 2013 - Second support device; 2014 - Third support device; 2015 - Fourth support device; 20121 - Cylinder; 20122 - Sensor connection plate; 20123 - Pressure sensor; 20124 - Support head connection plate; 20125 - Inner surface support head; 20126 - Clamping bolt; 202 - Pneumatic drive device; 2021 - First drive group; 2022 - Second drive group; 2023 - Third drive group; 2024 - Fourth drive group; 20211 - Solenoid valve; 20212 - Electric proportional valve; 20213 - Signal converter;

[0068] 300 - deformation monitoring module; 301 - first deformation monitoring device; 302 - second deformation monitoring device; 303 - third deformation monitoring device; 304 - fourth deformation monitoring device; 3011 - eddy current displacement sensor; 3012 - displacement sensor mounting plate; 3013 - front box;

[0069] 400-control module;

[0070] 500-Thin-walled ring parts. DETAILED DESCRIPTION

[0071] The present invention will be further described below with reference to the accompanying drawings.

[0072] like Figure 1 As shown, the active control device for elastic deformation of thin-walled annular parts provided by the present invention includes a clamping module 100, an active supporting module 200, a deformation monitoring module 300 and a control module 400.

[0073] The clamping module 100 is used to perform circumferential positioning and axial clamping of the thin-walled annular part being processed;

[0074] The active support module 200 is used to provide adjustable, multiple independent, and equal lateral support forces to the inner surface of the thin-walled annular component; the active support module 200 has a support force detection function and can send the support force it provides to the control module;

[0075] The deformation monitoring module 300 is used to monitor the deformation of thin-walled annular parts during processing;

[0076] The control module 400 is used to control the operation of the active support module 200 and the deformation monitoring module 300, and to process the support force data detected by the active support module 200 and the elastic deformation data detected by the deformation monitoring module 300 to obtain the deformation field and control parameters of the thin-walled annular part, and then issue control instructions to the active support module 200.

[0077] The following will be described in detail for each part.

[0078] I. Clamping module

[0079] The clamping module 100 comprises a clamping sub-module 101 and a positioning sub-module 102.

[0080] As shown in Figure 2 , the clamping sub-module 101 is used to realize axial clamping of the thin-walled annular part; the clamping sub-module 101 comprises a clamping bottom plate 1011, a double-head flange support column 1012 and a clamping cover plate 1013 connected in sequence from bottom to top, and the clamping bottom plate 1011 and the double-head flange support column 1012, the clamping cover plate 1013 and the double-head flange support column 1012 are connected and fastened by the bolt set 1014. The height of the double-head flange support column 1012 is determined according to the height of the thin-walled annular part to be processed, and the shape of the clamping bottom plate 1011 and the clamping cover plate 1013 is not limited, as long as the thin-walled annular part to be processed can be clamped between the clamping bottom plate 1011 and the clamping cover plate 1013. The upper surface of the clamping bottom plate 1011 is also provided with a plurality of arc-shaped holes 10111, a plurality of strip-shaped grooves 10112 and a plurality of mounting holes 10113; the arc-shaped holes 10111 and the strip-shaped grooves 10112 are used for the discharge of cooling liquid in the processing process to avoid the damage of device components caused by the accumulation of cooling liquid; the mounting holes 10113 are used to realize the installation of the electromagnetic valve and the electrical proportional valve in the positioning sub-module and the driving support module 200, wherein the mounting holes for installing the positioning sub-module have multiple groups, and each group can be distributed on different sizes of circumferences to facilitate the adjustment of the positioning size of the positioning sub-module.

[0081] As shown in Figure 3As shown, the positioning sub-module 102 is arranged on the upper end face of the clamping base plate 1011, and is used to cooperate with the inner profile of the thin-walled annular part to realize the positioning of the thin-walled annular part; the positioning sub-module 102 includes a first positioning ring 1021, a second positioning ring 1022, a third positioning ring 1023 and a fourth positioning ring 1024, each of which has two countersunk bolt through holes; the first positioning ring 1021, the second positioning ring 1022, the third positioning ring 1023 and the fourth positioning ring 1024 are fixedly installed on the upper end face of the clamping base plate 101 by being screwed into the countersunk bolt through holes, and the first positioning ring 1021, the second positioning ring 1022, the third positioning ring 1023 are uniformly distributed along the same circumference, and the side walls thereof are adapted to the inner wall profile of the thin-walled annular part being machined. Since the clamping base plate 1011 is provided with a plurality of mounting holes for mounting the positioning sub-module, the size of the circumference formed by the four positioning rings can be adjusted, thereby meeting the positioning requirements of thin-walled annular parts of different diameters. In addition, it should be noted that the present embodiment is an exemplary description of four positioning rings, and in other embodiments, the number of positioning rings can be appropriately adjusted according to the size of the inner profile of the thin-walled annular part being machined; the larger the diameter of the thin-walled annular part, the more positioning rings are required.

[0082] II. Active support module

[0083] As shown in Figure 4 , the active support module 200 includes a pneumatic execution device 201 and a pneumatic driving device 202 arranged on the clamping base plate 1011. The pneumatic execution device 201 is used to move horizontally under the drive of the pneumatic driving device 202 to push against the inner wall of the thin-walled annular part, thereby providing support force to the inner wall of the thin-walled annular part.

[0084] As shown in Figure 5 , the pneumatic execution device 201 includes a support base 2011, a first support device 2012, a second support device 2013, a third support device 2014 and a fourth support device 2015. The legs of the support base 2011 are fixedly installed on the clamping base plate 1011, the table top of the support base 2011 is used to support and install the first support device 2012, the second support device 2013, the third support device 2014 and the fourth support device 2015, and the first support device 2012, the second support device 2013, the third support device 2014 and the fourth support device 2015 are uniformly distributed along the same circumference. Similarly, the present embodiment is an exemplary description of four support devices, and in other embodiments, the number of support devices can be appropriately adjusted according to the size of the inner profile of the thin-walled annular part being machined; the larger the diameter of the thin-walled annular part, the more support devices are required.

[0085] The first supporting device 2012, the second supporting device 2013, the third supporting device 2014 and the fourth supporting device 2015 are of the same structure, and only the structure of the first supporting device 2012 is taken as an example for description.

[0086] As shown in Figure 6 , the first supporting device 2012 comprises a cylinder 20121, a sensor connecting plate 20122, a pressure sensor 20123, a supporting head connecting plate 20124 and an inner profile supporting head 20125 connected in sequence, and a clamping bolt 20126.

[0087] The cylinder 20121 has a plurality of countersunk bolt holes on the cylinder body, and the supporting base 2011 is provided with threaded holes corresponding to the countersunk bolt holes, so that the cylinder 20121 can be fixedly installed on the tabletop of the supporting base 2011 by screwing bolts into the countersunk bolt holes.

[0088] The push rod end face of the cylinder 20121 is provided with a through hole, and the sensor connecting plate 20122 is provided with a countersunk bolt hole corresponding to the through hole, so that the sensor connecting plate 20122 can be fixedly connected with the push rod of the cylinder 20121 by screwing a bolt into the countersunk bolt hole.

[0089] The bottom of the pressure sensor 20123 is provided with a threaded hole, and the sensor connecting plate 20122 is provided with a countersunk bolt hole corresponding to the threaded hole, so that the pressure sensor 20123 can be fixedly connected with the sensor connecting plate 20122 by screwing a bolt into the countersunk bolt hole. At the same time, the sensor connecting plate 20122 is also provided with a through hole near the edge, and the supporting head connecting plate 20124 is provided with a countersunk threaded hole corresponding to the through hole, so that the pressure sensor 20123 can be arranged between the supporting head connecting plate 20124 and the sensor connecting plate 20122 by means of the corresponding holes and the clamping bolt 20126, and the specified direction of the pressure sensor 20123 can be limited and the pre-tightening force can be applied by adjusting the clamping bolt 20126.

[0090] One end of the inner profile supporting head 20125 is a flat surface, and the other end is an arc surface matched with the inner wall of the thin-walled annular part to be machined; the inner profile supporting head 20125 is provided with a countersunk bolt hole on the flat surface, and the supporting head connecting plate 20124 is provided with a threaded hole corresponding to the countersunk bolt hole, so that the inner profile supporting head 20125 can be fixedly connected with the supporting head connecting plate 20124 by screwing a bolt into the countersunk bolt hole.

[0091] As shown in Figure 7 , the pneumatic driving device 202 comprises a first driving group 2021, a second driving group 2022, a third driving group 2023 and a fourth driving group 2024 arranged on the clamping bottom plate 1011.

[0092] The first driving group 2021, the second driving group 2022, the third driving group 2023 and the fourth driving group 2024 are of the same structure, and hereinafter the structure of the first driving group 2021 will be taken as an example for description.

[0093] The first driving group 2021 comprises an electromagnetic valve 20211, an electric proportional valve 20212 and a signal converter 20213 arranged on the clamping bottom plate 1011. The electromagnetic valve 20211 and the electric proportional valve 20212 are connected with the air cylinders of the supporting devices in the pneumatic execution device 201, and the electric proportional valve 20212 is used to adjust the pressure of the pressure gas provided by the gas source to a specified gas pressure, and then the gas at the specified gas pressure is transmitted to the air cylinders of the supporting devices in the pneumatic execution device 201 through the electromagnetic valve 20211. The signal converter 20213 is connected with the pressure sensors of the supporting devices in the pneumatic execution device 201, and is used to convert the electric signal output by the pressure sensors into a signal recognizable by the PLC in the control module 400, and transmit the signal to the PLC and the upper computer for data processing and control.

[0094] There is no direct signal transmission between the electric proportional valve 20212, the electromagnetic valve 20211 and the signal converter 20213, and they are controlled by the PLC in the control module 400 as the main control to realize the control cooperation, which will be described in detail in the subsequent description of the control module 400.

[0095] It should be particularly pointed out here that the pneumatic execution device 201 in the active supporting module 200 and the pneumatic driving device 202 can be replaced by electric / hydraulic execution devices and electric / hydraulic driving devices respectively, as long as they can realize the controllable support of the inner profile of the thin-walled annular workpiece, and the corresponding adaptive adjustment of other parts required to cooperate with them can be made, and the specific adaptive adjustment is a conventional technical means in the mechanical field, which will not be described here.

[0096] In addition, for the thin-walled annular workpiece with a small axial size, the active supporting module 200 in the present application is one, and can be used alone to meet the radial support requirements, for example, the thin-walled annular workpiece and the active supporting module 200 in the present embodiment; however, when the axial size of the thin-walled annular workpiece is large, the active supporting module 200 in the present application can be multiple, and the multiple active supporting modules 200 are arranged along the axial direction, for example, two active supporting modules 200 arranged above and below can be used to respectively support the upper part and the middle and lower parts of the thin-walled annular workpiece, as shown in Figure 13 When multiple active supporting modules are used, the active supporting module at the upper level can be fixed on the table top of the supporting base of the active supporting module at the lower level, or the supporting base thereof can be fixedly connected with the flange supporting column in the clamping module, so as to be fixed.

[0097] 3. Deformation Monitoring Module

[0098] like Figure 8 As shown, the deformation monitoring module 300 is used to monitor the elastic deformation of the thin-walled annular part in real time during the processing, and includes a first deformation monitoring device 301, a second deformation monitoring device 302, a third deformation monitoring device 303 and a fourth deformation monitoring device 304 arranged on the table of the support base 2011.

[0099] The first deformation monitoring device 301 , the second deformation monitoring device 302 , the third deformation monitoring device 303 and the fourth deformation monitoring device 304 have the same structure, and only the structure of the first deformation monitoring device 301 is used as an example for description.

[0100] The first deformation monitoring device 301 includes an eddy current displacement sensor 3011 , a displacement sensor mounting plate 3012 and a front box 3013 .

[0101] The displacement sensor mounting plate 3012 is used to mount the eddy current displacement sensor 3011 on the tabletop of the support base 2011. The eddy current displacement sensor 3011 is used to detect the elastic deformation of the inner surface of the thin-walled annular part being processed. The number of eddy current displacement sensors 3011 in the deformation monitoring module 300 is consistent with the number of support devices in the active support module 200. All eddy current displacement sensors 3011 are arranged in a circular array along the circumference of the thin-walled annular part, and an eddy current displacement sensor 3011 is provided between every two support devices. In this way, four characteristic points on the inner surface of the thin-walled annular part being processed can be monitored simultaneously. The eddy current displacement sensor 3011 can also be replaced by an inductive displacement sensor, a capacitive displacement sensor, a laser displacement sensor, an LVDT sensor, etc. The pre-box 3013 is used in conjunction with the eddy current displacement sensor 3011 to provide the power required by the eddy current displacement sensor 3011 and to amplify, detect and filter the signal output by the eddy current displacement sensor 3011; the pre-box 3013 is an existing mature product.

[0102] In this embodiment, the displacement sensor mounting plate 3012 is an L-shaped plate, the bottom plate of which is fixedly mounted on the table of the support base 2011 by bolts, and the side plates thereof are processed with threaded holes for mounting the eddy current displacement sensor 3011 .

[0103] The outer surface of the eddy current displacement sensor 3011 is a threaded structure. The eddy current displacement sensor 3011 is screwed into the threaded hole on the side plate of the displacement sensor mounting plate 3012 and matched with a nut for connection and measurement range adjustment.

[0104] The front box 3013 is fixedly mounted on the table of the support base 2011 by means of bolts.

[0105] IV. Regulation module

[0106] The regulation module 400 is used to control the active support module 200 and the deformation monitoring module 300 to work, and process the support force data detected by the active support module 200 and the elastic deformation data detected by the deformation monitoring module 300, so as to obtain the deformation field of the thin-walled ring-shaped part and the support force regulation parameters of the active support module, and then issue the regulation instruction to the active support module 200. The regulation module 400 comprises an industrial computer, a PLC, a digital-analog conversion module, a data acquisition module, a power supply and an air compressor. The industrial computer is pre-stored with s elastic deformation prediction models, which are one-to-one corresponding to each process of the thin-walled ring-shaped part, and are respectively used to predict the elastic deformation after each machining node in each process is machined. For any process, the experimentally calibrated milling force, the pre-set target support force, the boundary condition, the material property, the contact condition and the elastic deformation extraction point are input into the corresponding elastic deformation prediction model, so as to obtain the predicted value of the elastic deformation at the elastic deformation extraction point after each machining node in the process is machined. The pre-set target support force is determined by the support force regulation curve of each machining node, and the support force regulation curve is a curve of the support force changing with the machining node (or time). The support force regulation curve of each machining node and the establishment method of the elastic deformation prediction model will be described in detail in the active control method of elastic deformation. The support force regulation curve of each machining node is pre-stored in the PLC, which is the basis for setting and adjusting the support force. At the same time, the voltage signal 0-10V is set to correspond to the air pressure value 0-0.5Mpa in the PLC, and the 0-10V voltage signal is set to correspond to the 0-20000 digital signal in the analog quantity conversion module. At this time, the setting of the air pressure value and the analog quantity signal can be expressed as The conversion relationship between the analog quantity signal and the digital quantity signal can be expressed as Wherein V is the analog quantity signal, and D is the digital quantity signal.

[0107] The functions of each part are as follows:

[0108] Before the machining process starts, the industrial computer sends the first control instruction to the PLC. The PLC cooperates with the digital-analog conversion module to send the corresponding analog quantity signal to all electrical proportional valves 20212 of the pneumatic driving device 202 in the active support module 200 based on the pre-stored support force regulation curve in the PLC, so as to set the initial air source air pressure. Then, the PLC sends the digital quantity signal to all electromagnetic valves 20211 of the pneumatic driving device 202 in the active support module 200 through the IO port, so as to control the synchronous extension and retraction of all cylinders 20121 of the pneumatic actuator 201 in the active support module 200, and set the initial state of the active support module 200. Then, the normal milling program starts.

[0109] Then, during the processing, the PLC sends a first request instruction to all pressure sensors 20123 of the pneumatic actuator in the active support module 200, the data acquisition module reads the monitoring values of each pressure sensor 20123 in the active support module 200 to the PLC, and the PLC compares the support force monitoring value with the support force set value determined by the support force control curve. If they are inconsistent and need to be adjusted to the set value, the PLC uses the PID algorithm to cooperate with the digital-to-analog conversion module for feedback adjustment until the active support module 200 provides the required support force to the thin-walled annular part, realizing the active control of the support force in the process.

[0110] After the current process is completed, before the next process starts, the industrial computer sends a second request instruction to the eddy current displacement sensor 3011 in the deformation monitoring module 300, the data acquisition module reads the monitoring values of all eddy current displacement sensors 3011 to the industrial computer, and the industrial computer performs data fitting to obtain the actual deformation field of the inner surface of the thin-walled annular part. Then, the industrial computer compares the actual deformation field with the predicted deformation field predicted by the elastic deformation prediction model, calculates the required support force compensation amount of each processing node in the next process through Hooke's law, and all support devices correspond to the same support force compensation amount.

[0111] After the current process is completed, before the next process starts, the industrial computer sends a second control instruction to the PLC to adjust the control parameters of the active support module 200. Specifically, the industrial computer determines the required support force according to the support force compensation amount of the next process obtained above and transmits it to the PLC, and then the PLC converts the support force and the air pressure value according to the relationship F s =P·S c to determine the required air pressure value after compensation (P is the air pressure value, S c is the effective area of the cylinder piston, and F s is the support force), and the PLC sends an analog signal corresponding to the compensated air pressure value to all electric proportional valves 20212 of the pneumatic drive device 202 in the active support module 200 through the digital-to-analog conversion module, thereby realizing the adaptive adjustment of the support force. This control method does not need to re-clamp the thin-walled annular part, ensuring the accuracy and efficiency of the processing.

[0112] According to the requirements of the processing process, the active support module 200 and the data monitoring module 300 can be controlled through the above control instructions and request instructions throughout the entire processing process, thereby realizing the elastic deformation adaptive control of the thin-walled annular part milling.

[0113] The monitoring screen of the industrial computer displays the deformation monitoring results and related information of each controlled component.

[0114] Power supply is used to supply power to the industrial computer, PLC, displacement sensor 3011, pressure sensor 20123, electric proportional valve 20212 and solenoid valve 20211.

[0115] Air compressor is used to provide air source for the cylinder 20121 of the active support module 200.

[0116] Referring to Figure 11 The working process and principle of the thin-walled ring part machining elastic deformation active control device are as follows:

[0117] Step one: install the clamping sub-module 101 on the machine tool workbench and fix it, install the positioning sub-module 102 and the thin-walled ring part 500 together on the clamping sub-module 101, and press the clamping cover plate 1013 of the clamping sub-module 101 to complete the clamping of the thin-walled ring part 500;

[0118] Step two: turn on the power supply and start the thin-walled ring part machining elastic deformation active control device.

[0119] Step three: set the initial support force on the industrial computer and control the inner surface support head 20125 of the pneumatic execution device 201 in the active support module 200 to extend to support the inner wall of the thin-walled ring part 500.

[0120] Step four: start the specified process, due to the time-varying characteristics of the cutting force, the support force will fluctuate during machining, in order to provide stable support force, the support force data is collected by the pressure sensor of each support device in the active support module 200 and feedback adjustment is made by using PID algorithm; at the same time, due to the weak rigidity of the thin-walled ring part 500, the thin-walled ring part will produce elastic deformation to different degrees during machining, the deformation data of the workpiece in the current machining process is obtained by the eddy current displacement sensor of each deformation monitoring device in the deformation monitoring module 300 and the deformation field of the workpiece in the current machining process is calculated by the joint control module 400;

[0121] Step five: after the current process is completed, all the inner surface support heads 20125 of the pneumatic execution device 201 in the active support module 200 retract and are separated from the inner wall of the thin-walled ring part, the initial support force required for the next process is compensated according to the deformation field of the current process, and then all the inner surface support heads 20125 of the pneumatic execution device 201 in the active support module 200 extend again to support the inner wall of the thin-walled ring part 500.

[0122] Step six: repeat steps three and five until all processes are completed.

[0123] In addition to the above-mentioned thin-walled ring part machining elastic deformation active control device, the present application also provides a thin-walled ring part machining elastic deformation active control method, the specific steps of which are as follows:

[0124] Step 1: Obtain the deformation field and stiffness field after each process, as well as the support force control curve within each process;

[0125] Step 1.1 Create CAD models after each process is completed and import these CAD models into finite element simulation software;

[0126] Step 1.2: Determine the range of fixed support force corresponding to each process based on the milling force obtained through experimental calibration.

[0127] Step 1.3: For each process, within the range of the corresponding fixed support force, select k fixed support force values ​​according to the set step size, and establish a set of first elastic deformation prediction models for it based on the CAD model after the process is completed and through finite element simulation. The set of first elastic deformation prediction models includes k models, each corresponding to the k fixed support force values. For s processes, s sets of first elastic deformation prediction models need to be constructed. After the first elastic deformation prediction model is established, set the parameters of the first elastic deformation prediction model, including milling force, support force, boundary conditions, material properties, and contact conditions. The milling force is obtained by experimental calibration, and the support force is the k fixed support force values ​​selected according to the set step size.

[0128] Step 1.4: For each process, a milling path is first set, which includes n processing nodes. Since each processing node corresponds to k first elastic deformation prediction models, after simulation, k sets of elastic deformation data can be obtained for the n processing nodes of each process.

[0129] Step 1.5: For each process, construct a data set with k groups of elastic deformation data and corresponding fixed support force values ​​corresponding to each processing node in the process, and use the numerical fitting method to solve the functional relationship between the elastic deformation and support force at each processing node in the process. By setting constraints, the elastic deformation is constrained within the tolerance range of the design requirements, and the functional relationship is solved to obtain the target support force of each processing node in the process.

[0130] Step 1.6 For each process, perform function interpolation and fitting on the target support force of each processing node in the process to obtain the support force control curve of each processing node in the process, which is used as the basis for adjusting the support force in each process; a total of s support force control curves are obtained for s processes.

[0131] Step 1.7: A second elastic deformation prediction model is established for each process by finite element simulation, and parameters of the elastic deformation prediction model are set, including milling force, support force, boundary condition, material property, and contact condition; wherein the milling force is still the milling force calibrated by experiment, and the support force is valued according to the support force regulation curve of each machining node in the process; s second elastic deformation prediction models are needed in total for s processes.

[0132] Step 1.8: For each process, a milling path is first set, which includes n machining nodes, and after simulation, elastic deformation data of the n machining nodes after machining in the process can be obtained, each machining node corresponding to an elastic deformation data; the elastic deformation data are arranged according to the positions of the machining nodes, and thus a deformation field of the workpiece after machining in the process can be obtained.

[0133] Step 1.9: The stiffness field of the workpiece is calculated according to the deformation field of the workpiece after machining in each process.

[0134] Step 2: In the current machining process, based on the support force regulation curve of each machining node in the process obtained in step 1.6, the support force provided by all support devices for supporting the inner wall of the thin-walled ring-shaped workpiece is adjusted by using a closed-loop feedback control method;

[0135] Step 3: After the current process is completed, the support force compensation amount of the next process is obtained;

[0136] Step 3.1: z feature points are selected on the rigid weak area of the inner surface of the thin-walled ring-shaped workpiece, and elastic deformation detection devices are arranged at the feature points, and the measured data of the elastic deformation at the z feature points are obtained by using the elastic deformation monitoring devices.

[0137] Step 3.2: z elastic deformation extraction points corresponding to the z feature points are set on the second elastic deformation prediction model, and after simulation, the predicted data of the elastic deformation at the z feature points can be obtained.

[0138] Step 3.3: After the current process is completed, by comparing the measured data and the predicted data of the elastic deformation at the z feature points, the elastic deformation prediction error can be obtained, and then the support force compensation amount is obtained, and the support force preset value of each machining node in the next process is compensated by using the support force compensation amount, wherein the support force preset value is a value determined according to the support force regulation curve.

[0139] The method for obtaining the support force compensation amount is as follows:

[0140] In any current process, the actual cutting depth of the workpiece can be expressed as de,i=dp,i+ei, wherein d e,iand dp,i are the actual and designed cutting depths in the process, and ei is the machining error of each machining position. The machining error ei will accumulate with the progress of the process, eventually leading to the workpiece exceeding the tolerance. In the machining process, the influence of the support force and the milling force on the deformation of the workpiece can be regarded as the superposition of deformation in two directions, therefore, in order to offset the deformation, the support force needs to be changed in the next process to compensate for it. The support force compensation amount is ΔF s = K G ·e i , wherein K G is the workpiece stiffness field obtained by using the second elastic deformation prediction model in step 1.

[0141] Step 4: The support force compensation amount of the next process determined in step 3 and the preset support force value corresponding to each machining node in the next process on the support force control curve are superimposed respectively, that is, the actual support force required by each machining node in the next process is obtained, and the actual support force is taken as the support force provided by all support devices for supporting the inner wall of the thin-walled annular workpiece.

[0142] Step 5: Steps 2-4 are executed in a loop until all processes are completed.

Claims

1. An active control device for elastic deformation during machining of thin-walled annular parts, characterized by: It includes clamping module, active support module, deformation monitoring module and control module; The clamping module is used to perform circumferential positioning and axial clamping of the thin-walled annular parts being processed; The active support module is used to provide adjustable, multiple independent, and equal radial support forces to the inner surface of the thin-walled annular component; the active support module has a support force detection function and can send the support force it provides to the control module; The deformation monitoring module is used to monitor the elastic deformation of thin-walled ring parts during processing; The control module is used to control the operation of the active support module and the deformation monitoring module. The control module also has an elastic deformation prediction model and a support force control curve for each processing node preset; The control module uses closed-loop feedback control within the process to adjust the support force provided by the active support module based on the support force data detected by the active support module and the support force control curve; it can also process the support force data detected by the active support module and the elastic deformation data detected by the deformation monitoring module before the start of the next process to obtain the actual deformation field of the thin-walled annular part in the previous process, and compare the actual deformation field with the deformation field of the previous process predicted by the elastic deformation prediction model to obtain the support force compensation amount of the next process, and based on the support force compensation amount and the support force control curve, send a support force control instruction to the active support module before the start of the next process to realize support force control between processes.

2. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 1, characterized in that: The clamping module includes a clamping sub-module and a positioning sub-module; the clamping sub-module includes a clamping base plate, a double-headed flange support column and a clamping cover plate connected in sequence from bottom to top, and the thin-walled annular part is clamped by the clamping base plate and the clamping cover plate; the positioning sub-module includes at least three positioning rings arranged on the clamping base plate and distributed along the same circumference, and the outer wall of the positioning ring is adapted to the inner wall profile of the thin-walled annular part.

3. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 2, characterized in that: The upper surface of the clamping base is provided with a plurality of arc-shaped holes, a plurality of strip-shaped grooves and a plurality of mounting holes; the arc-shaped holes and the strip-shaped grooves are used for discharging coolant during the processing; the mounting holes are used for installing the positioning submodule; there are multiple groups of mounting holes, each group being distributed on a circumference of different sizes so as to adjust the positioning size of the positioning submodule.

4. The active control device for elastic deformation during machining of thin-walled annular parts according to any one of claims 1 to 3, characterized in that: The active support module includes a driving device disposed on a clamping base plate and an actuator having a support force detection function; the actuators are m in number and are evenly distributed along the same circumference. Driven by the driving device, the actuators can independently move radially to support the inner wall of the thin-walled annular member; the driving device is connected to the control module, and its operation is controlled by the control module; m≥3； The actuator is a pneumatic actuator, an electric actuator or a hydraulic actuator, and correspondingly, the drive device is a pneumatic drive device, an electric drive device or a hydraulic drive device.

5. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 4, characterized in that: The actuator is a pneumatic actuator, comprising a support base and m support devices; the legs of the support base are fixedly mounted on the clamping base, and the table of the support base is used to support and mount the m support devices; A single support device includes a cylinder, a sensor connecting plate, a pressure sensor, a support head connecting plate, and an inner surface support head connected in sequence; the cylinder is mounted on the table of the support base, the sensor connecting plate is fixedly connected to the push rod of the cylinder; the sensor connecting plate is connected to the support head connecting plate by clamping bolts; The driving device is a pneumatic driving device, including m driving groups arranged on the clamping base plate; a single driving group includes a solenoid valve, an electrical proportional valve and a signal converter arranged on the clamping base plate; the solenoid valve and the electrical proportional valve are connected to the cylinder, the electrical proportional valve is used to adjust the gas pressure entering the cylinder to a specified air pressure, and the solenoid valve is used to transmit the gas of the specified air pressure to the cylinder; the signal converter is connected to the pressure sensor, and is used to convert the electrical signal output by the pressure sensor into a signal recognizable by the control module.

6. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 5, characterized in that: There are one or more active support modules; when there are multiple active support modules, they are arranged in sequence along the axial direction and used in combination to support different axial areas of the thin-walled annular component.

7. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 6, characterized in that: The deformation monitoring module includes m deformation monitoring devices arranged on the table of the support base; the m deformation monitoring devices are evenly distributed along the circumference, and a deformation monitoring device is provided between every two support devices; a single deformation monitoring device includes a displacement sensor and a front box; The displacement sensor is installed on the table of the support base through the displacement sensor mounting plate. The displacement sensor is used to detect the elastic deformation of the inner surface of the thin-walled annular part; the front box is used to provide the power required by the displacement sensor and amplify, detect and filter the signal output by the displacement sensor.

8. The active control device for elastic deformation during machining of thin-walled annular parts according to claim 7, characterized in that: The control module includes an industrial computer, a PLC, a digital-to-analog conversion module, a data acquisition module, a power supply, and an air compressor; the industrial computer is pre-installed with the elastic deformation prediction model; the PLC is pre-installed with the support force control curve of each processing node, and the PLC is set with the corresponding relationship between the voltage signal and the air pressure value; Before the start of the processing process, the industrial computer sends a first control instruction to the PLC. The PLC cooperates with the digital-to-analog conversion module to send corresponding analog signals to all the electrical proportional valves of the pneumatic drive device in the active support module based on the received first control instruction and the support force control curve, thereby setting the initial air source pressure. Subsequently, the PLC sends digital signals to all the solenoid valves of the pneumatic drive device in the active support module through the IO port to control the synchronous extension and retraction of all the cylinders of the pneumatic actuator in the active support module, thereby setting the initial state of the active support module. Then, the PLC sends a first request instruction to all pressure sensors of the pneumatic actuators in the active support module. The data acquisition module reads the monitoring values ​​of each pressure sensor in the active support module to the PLC, and the PLC compares the support force monitoring value with the support force set value. If there is any inconsistency and it needs to be adjusted to the set value, the PLC uses the PID algorithm in conjunction with the digital-to-analog conversion module to perform feedback adjustment until the active support module provides the required support force to the thin-walled annular part, and then starts the normal milling process. During the machining process, the industrial computer sends a second request command to the displacement sensor in the deformation monitoring module. The data acquisition module reads the monitoring values ​​of all displacement sensors to the industrial computer, which then performs data fitting to obtain the actual deformation field of the inner surface of the thin-walled annular part. The industrial computer then compares the actual deformation field with the workpiece deformation field predicted by the elastic deformation prediction model and calculates the support force compensation required for the next process using Hooke's law. All support devices correspond to the same support force compensation. Between processes, the industrial computer determines the required supporting force based on the supporting force compensation amount of the next process obtained previously and transmits it to the PLC. The PLC then converts the supporting force into air pressure value to determine the air pressure value required after the supporting force compensation. The PLC sends an analog signal corresponding to the compensated air pressure value to all the electrical proportional valves of the pneumatic drive device in the active support module through the digital-to-analog conversion module, thereby realizing adaptive adjustment of the supporting force.

9. A method for actively controlling elastic deformation during machining of thin-walled annular parts, characterized in that: The following steps are involved: Step 1: Obtain the deformation field and stiffness field after each process, as well as the support force control curve within each process; Step 1.1 Create a CAD model after each process and import it into the finite element simulation software; Step 1.2: Determine the range of fixed support forces corresponding to each process based on the experimentally calibrated milling forces within the process. Step 1.3: For each process, within the range of the corresponding fixed support force, select k fixed support force values ​​according to the set step size. Based on the CAD model after the process is completed and through finite element simulation, establish a set of first elastic deformation prediction models for it. This set of first elastic deformation prediction models includes k models, each corresponding to the k fixed support force values. For s processes, s sets of first elastic deformation prediction models need to be constructed. After the model is established, set the model parameters, including milling force, support force, boundary conditions, material properties, and contact conditions. The milling force is obtained by experimental calibration, and the support force is the k fixed support force values ​​selected according to the set step size. Step 1.4: For each process, set a milling path, which includes n processing nodes. After simulation, k sets of elastic deformation data can be obtained for each process's n processing nodes. Step 1.5: For each process, construct a data set using k sets of elastic deformation data and corresponding fixed support force values ​​for each processing node in the process. Use numerical fitting to solve the functional relationship between elastic deformation and support force at each processing node in the process. Set constraints to constrain the elastic deformation within the design tolerance range, and solve this functional relationship to obtain the target support force for each processing node in the process. Step 1.6: For each process, perform function interpolation and fitting on the target support force of each processing node in the process to obtain the support force control curve of each processing node in the process; a total of s support force control curves are obtained for s processes; Step 1.7: Build a second elastic deformation prediction model for each process through finite element simulation and set the parameters of the elastic deformation prediction model, including milling force, support force, boundary conditions, material properties, and contact conditions. The milling force is still the milling force calibrated by the experiment, and the support force is determined according to the support force control curve of each processing node in the process. A total of s second elastic deformation prediction models are required for s processes. Step 1.8: For each process, a milling path is first set. This milling path includes n processing nodes. After simulation, the elastic deformation data of each processing node in the process is obtained. Each processing node corresponds to an elastic deformation data. The elastic deformation data are arranged according to the position of the processing node to obtain the deformation field of the workpiece after the process is completed. Step 1.9 calculates the stiffness field of the workpiece based on the deformation field of the workpiece after each processing step; Step 2: In the current processing step, based on the support force control curves for each processing node of the process obtained in step 1.6, the support force provided by all support devices used to support the inner wall of the thin-walled annular part is adjusted within the process using a closed-loop feedback control method; Step 3: After the current process is completed, obtain the support force compensation amount for the next process; Step 3.1: Select z characteristic points in the rigidity weak area on the inner surface of the thin-walled annular component, and set an elastic deformation detection device at each characteristic point, and use these elastic deformation monitoring devices to obtain measured data of elastic deformation at the z characteristic points; Step 3.2: setting z elastic deformation extraction points corresponding to the z feature points on the second elastic deformation prediction model, and obtaining the predicted data of the elastic deformation at the z feature points after simulation; Step 3.3 After the current process is completed, the measured data of elastic deformation at the z feature points are compared with the predicted data to obtain the elastic deformation prediction error, and then the support force compensation amount is obtained. This support force compensation amount is used to compensate the support force preset value of each processing node in the next process. The support force preset value is determined according to the support force control curve. Step 4: The support force compensation amount of the next process determined in step 3 is superimposed on the support force preset value corresponding to each processing node in the next process on the support force control curve, thereby obtaining the actual support force required for each processing node in the next process. This actual support force is used as the support force provided by all support devices for supporting the inner wall of the thin-walled annular part. Step 5: Repeat steps 2-4 until all processes are completed.

10. The method for actively controlling elastic deformation during machining of thin-walled annular parts according to claim 9, characterized in that: The method for obtaining the support force compensation is: In any current process, the actual cutting depth of the workpiece can be expressed as de,i=dp,i+ei, where d e,i and dp,i are the actual cutting depth and designed cutting depth in the process respectively, and ei is the machining error of each machining position; The support force compensation is ΔF s =K G ·e i , where K G is the workpiece stiffness field obtained in step 1 using the second elastic deformation prediction model.

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