Large complex ellipsoidal part machining deformation control method based on dynamic cutting planning

Abstract

Disclosed in the present invention is a large complex ellipsoidal part machining deformation control method based on dynamic cutting planning. The method comprises: performing initial clamping on a blank part, constructing a machining coordinate system, completing reference non-contact measurement and reference surface fitting of inner and outer shape surfaces of the blank part, and completing the division of a generatrix tangent plane; on the basis of product feature decomposition, completing in the same coordinate system the comparison between each theoretical section and an actually measured section, completing cutting evaluation based on the generatrix tangent plane in a machining area, and guiding overall machining route planning and local machining route planning; on the basis of route planning and a cuttable margin, using an adjustable support device to complete part clamping based on dynamic adjustment, so as to realize stable cutting under a variable cutting thickness, and thereby solving the problem of overall deformation control of a large complex ellipsoidal part; and completing high-rib feature twist amount identification in combination with adjustable support, and completing tool path trajectory offset compensation on the basis of a relationship between a circumferential offset and an allowance, and thereby realizing precise compensation machining of a mesh after a local twist. The present invention solves the key difficulties of high-rib local twist deformation compensation and overall deformation control on the basis of ensuring the precision of the residual wall thickness during numerical control machining of a large complex thin-walled ellipsoidal part, thereby further improving the overall manufacturing reliability of a large complex ellipsoidal part.

Description

A deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning Technical Field

[0001] The invention belongs to the technical field of mechanical processing and relates to a deformation control method for processing a large complex ellipsoidal part based on dynamic cutting planning. Background Art

[0002] With the rapid advancement of aerospace technology, new aircraft products are moving towards lightweight, high-strength, and integrated design. Large, thin-walled, ellipsoidal curved parts formed by integral spinning are key components. Traditionally, these products are manufactured separately, then assembled using group tooling for fastening, restraint, and welding. This process, characterized by numerous steps, long welds, and a lengthy manufacturing cycle, requires extensive equipment and equipment, making it increasingly difficult to meet the demands for high reliability, efficient manufacturing, and integrated product development.

[0003] The new type of large-scale thin-walled ellipsoidal curved parts adopts a new solution of external grid processing after integral sheet metal spinning, which can significantly reduce the manufacturing cycle and improve product performance. At present, the thinning processing methods of large-scale complex thin-walled ellipsoidal curved parts formed by integral spinning include chemical milling and CNC machining. Chemical milling uses templates for manual marking, and chemical corrosion makes it difficult to accurately control the relationship between the fillet depth and radius, making it impossible to achieve precise thinning and weight control of the product. In addition, chemical milling pollutes the environment and does not meet the needs of green manufacturing development. Another way is overall CNC machining. However, after the product is formed, the reference surface and the theoretical surface deviate unpredictably, and the theoretical digital model cannot be used for processing. In addition, the overall ellipsoidal structure of the product cannot be clamped against the mold, and the local part is a weak rigid thin-walled part, which is very prone to deformation and deviation. The above difficulties make the overall CNC machining quality control extremely difficult.

[0004] In order to achieve high-performance processing of this type of key products, domestic experts and scholars have conducted a series of studies. In terms of process methods, they have proposed an integrated measurement and processing method, using contact / non-contact measurement methods to complete the monitoring of the remaining wall thickness, which basically meets the requirements of equal wall thickness processing. Some experts and scholars have also proposed an overall mirror milling method, using dual five-axis follow-up support processing to efficiently meet the requirements of ultra-thin skin and other wall thickness processing. The above process methods have basically broken through the difficulties of equal wall thickness processing, but none of them mention how to solve the problems of local distortion and deformation of high-rib features and overall deformation control during the processing process. This is because the overall forming of the parts and the subsequent heat treatment process, as well as the removal of large-area allowances, will cause complex stress changes. If the overall constraint processing is used, the deformation after loosening and clamping is difficult to predict and control; and the local constraint process is also difficult to compensate for the accuracy of the distortion of the high-rib features through direct measurement.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the key difficulties of high-rib local distortion compensation and overall deformation control in the CNC machining of large and complex thin-walled ellipsoidal parts in the prior art, and to provide a large and complex ellipsoidal part machining deformation control method based on dynamic cutting planning.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning includes the following steps:

[0009] S1. Vertically clamp the blank part, build the machining coordinate system, complete the non-contact measurement and reference surface fitting of the inner and outer surface of the blank part, and complete the generatrix section division;

[0010] S2. Complete the comparison of each theoretical cross-section with the measured cross-section in the same coordinate system. Based on the product feature decomposition, complete the cutting evaluation of the processing area based on the generatrix section, and guide the overall processing route planning and local processing route planning;

[0011] S3. Overall machining and support adaptation: Based on path planning and machinability margins, adaptive support devices are used to achieve dynamic adaptive part clamping, stable cutting under variable cutting thickness, and solve the problem of overall deformation control while ensuring precise remaining wall thickness.

[0012] S4. Compensation processing after high-rib feature distortion: The roughing circumferential offset is △L, and the side wall roughing allowance is set to D. The increase of △L is observed during the cutting process. When △L=D is the limit value, the allowance D is first reduced to increase the margin. At the same time, the entire machining tool path moves L'=△LD in the direction of the △L deformation circle. When D>△L, the value during machining directly meets the compensation requirements.

[0013] S5. Utilize the relationship between the force and posture of the dynamic support area to further correct the error and achieve accurate processing compensation of the mesh after local distortion.

[0014] As a preferred embodiment, in step S1, a spatial rectangular coordinate system XYZ is established with the bottom surface of the large end of the part as a reference and the center of the bottom surface as the center of the circle.

[0015] As a preferred method, in step S2, parameter characterization of the actual process state blank part section and the theoretical model busbar section in the same coordinate system is completed; and the offset comparison of the actual blank part relative to the theoretical model busbar is completed.

[0016] Further preferably, in the step S2, the curve La is the actual outer surface after the blank is formed; the curve Lb is the actual inner surface after the blank is formed; the curve Lc is the theoretical inner surface of the product; Δh is the thickness distribution of the actual blank along the normal line, which is a gradual value from the small end to the large end; ΔS is the thickness difference between the actual inner surface Lb and the theoretical inner surface Lc along the normal line, which is above when Lc deviates outward and below when it deviates inward; La(xan, zan), Lb(xbn, zbn), and Lc(xcn, zcn) are points on the corresponding curves, and the intersection of the curves is the common point. S(bc-n) (n=1, 2, 3..) is the area of ​​the intersection of Lb and Lc, which represents the offset set, such as S(bc-1) and S(bc-2) are schematic diagrams of the upper offset and the lower offset, respectively;

[0017] f Lb (x) is the internal surface equation of the actual busbar section, f Lc (x) is the cross-sectional equation of the theoretical model busbar. The busbar is continuous after forming. When f Lb (x)>f Lc (x), the blank is offset toward the outside, and when f Lb (x)<f Lc (x), the blank is offset inward; when f Lb (x) = f Lc (x) is the point where the two points coincide (x gn ,y gn ), divide it by the common points, and solve the values ​​of the upper offset and the lower offset. Upper offset Bottom offset When P tends to 0, the overall deviation is the smallest; when P>0, the overall deviation is upward; when P<0, the overall deviation is downward;

[0018] According to the busbar section, the above offset calculations and comparisons are completed respectively.

[0019] As a preferred method, in step S2, the area to be removed of each feature region is K, the cutting depth at the small end is △h1, and the cutting depth at the large end is △h2, which is a variable cutting thickness; the first feature removal area is Total removal area on the busbar Local feature removal rate The evaluation index used to characterize the removal of a single feature on the section surface, the overall removal evaluation of the busbar is

[0020] According to the requirements of equal thickness processing, complete the resection evaluation calculation of the busbar section.

[0021] Further preferably, the actual blank of each cut surface is compared with the theoretical generatrix offset, and Mn is the characterization of the cutting variation margin on the generatrix cut surface m. Compare the cutting variation margins of each cutting surface m to obtain the size ranking of Mm. The distribution of Mm from large to small is the overall path planning order of the cutting generatrix section.

[0022] The local feature cutting variation allowance Kn' is compared, and the distribution of Kn' from large to small is the local path planning order of the selected busbar section.

[0023] As a preferred method, in step S3, the adjustable support device includes a bottom support area, a busbar support area and a movable support mechanism, the busbar support area is provided with a busbar support area slide, the bottom support area is provided with a movable support mechanism slide, the movable support mechanism includes a movable support movable mechanism, a multi-directional movable head and a movable support head, the movable support movable mechanism is arranged in the movable support mechanism slide, the movable support head is arranged in the busbar support area slide, the movable support movable mechanism and the multi-directional movable head are connected by a support rod, and the multi-directional movable head and the movable support head are connected by a support rod.

[0024] Further preferably, the movable support head includes a flexible support head, a flexible support pad and a sensor. The flexible support pad is arranged on the side of the flexible support head away from the busbar support area slide groove, and the sensor is used to monitor the support force and gap / sliding displacement in real time.

[0025] More preferably, the busbar support area is provided with adjustable auxiliary support screws.

[0026] As a preferred method, in step S3, based on the distribution of cutting variation margin on the busbar section and the processing path planning, the adjustable support device is driven and linked to the center of the cutting area. Combined with the index of the local cutting rate, the pneumatic clamping force is adjusted to achieve stable cutting under variable cutting thickness, thereby solving the problem of overall deformation control based on the precise guarantee of the remaining wall thickness.

[0027] As a preferred embodiment, in step S4, when ΔL exceeds the side rough machining allowance, the adjustable support device is readjusted.

[0028] According to the characteristics of the part being a large, complex, thin-walled ellipsoidal structure and having a high-rib cavity, the present invention first decomposes the product characteristics, constructs a processing coordinate system, completes the cross-section division of the busbar section, and simultaneously obtains the actual inner and outer shapes of the part based on a non-contact measurement method, generates a blank reference busbar, and completes the offset comparison with the theoretical reference busbar in the same coordinate system; under the constructed busbar section, the processing area is evaluated based on the structural characteristics, and the optimal deformation control process path planning for the overall processing and local feature processing is completed in combination with the busbar offset; based on the path planning and stiffness of the regional processing, an adaptive equipment is designed to meet the requirements of fast and reliable product support, meet the requirements of stable stiffness of the cavity area and adaptive adjustment of complex curved surface support, meet the requirements of real-time product deformation margin detection through sensors in the support area, meet the requirements of high-rib feature distortion compensation processing based on the detection results, and effectively integrate the device with the product and machine tool processing;

[0029] Specifically: construct a machining coordinate system, clamp parts vertically, complete non-contact measurement of the inner surface datum and datum surface fitting, and complete the busbar section division; complete the comparison of each theoretical section and the measured section in the same coordinate system, complete the cutting evaluation of the machining area based on the busbar section, and on this basis complete equal thickness machining and grid precise machining path planning. Based on path planning and machinable margin, design and utilize adjustable support devices to complete the clamping of large and complex thin-walled parts based on dynamic adaptation; carry out overall thinning machining, utilize support area perception and machining path planning to achieve controllable overall deformation; in the finishing stage, based on the requirements of distortion deformation and remaining wall thickness, combined with the machinable margin, complete the trajectory and compensation design of variable cutting thickness, during which the force and posture relationship of the dynamic support area are utilized to further correct the error, and realize precise mesh machining compensation after local distortion.

[0030] The present invention is not only applicable to integrally forming large thin-walled ellipsoidal parts, but is also applicable to processing other large thin-walled complex structural parts with a balance between medium wall thickness and deformation control.

[0031] The present invention has the following advantages:

[0032] This paper establishes an evaluation and comparison method based on the offset of the actual formed blank and the theoretical benchmark based on the generatrix section, completing the characterization of the processing performance of parts with different structural features and different deformation margins. On this basis, an adjustable support device suitable for large and complex ellipsoidal surfaces is designed to meet the high-speed processing requirements of different process paths and characteristics. By combining process path optimization, adjustable reliable support, and local processing compensation, it ultimately achieves product deformation control. This invention solves the key difficulties in CNC machining of large and complex thin-walled ellipsoidal parts, such as residual wall thickness, high-rib local distortion compensation, and overall deformation control, further improving manufacturing reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of the overall process of the present invention.

[0034] FIG2 is a schematic diagram of the cross-section distribution of the product blank generatrix of the present invention.

[0035] FIG3 is a schematic diagram of a cross section of the actual blank and the theoretical model of the product of the present invention.

[0036] FIG4 is a schematic diagram showing the corresponding distribution of product processing characteristics and busbar section areas of the present invention.

[0037] FIG5 is a schematic diagram of the grid processing sequence planning of the busbar cross-section area of ​​the present invention.

[0038] FIG6 is a schematic structural diagram of the adjustable support device of the present invention.

[0039] FIG7 is a partially enlarged view of FIG6 .

[0040] FIG8 is a schematic diagram of the cutting thickness of the local high-rib feature in the present invention.

[0041] FIG9 is a diagram comparing the actual processing of the local grid and the theoretical processing in the present invention. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to the accompanying drawings.

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] Example:

[0045] A blank is formed by integral spinning. The material is aluminum alloy, with a diameter of 3800 mm and an overall height of 900 mm. After the blank is formed, there are different degrees of deviation between the actual profile and the theoretical profile, and the processing requirement of equal wall thickness of 3 mm needs to be met.

[0046] A deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning includes the following steps:

[0047] Step 1: Establish a unified coordinate system for measurement and machining. As shown in Figure 2, the blank is clamped vertically after forming. Figure 6 shows an adjustable support device. Initially, screws and support positions are evenly spaced. The blank is vertically mounted on the 6-1 bottom support area to ensure flatness and secure the large end. A spatial rectangular coordinate system (XYZ) is established, using the large end bottom surface as the reference and the center of the bottom surface as the center of the circle. The intersection of the cross-section plane along the product ellipsoid generatrix and the product is the generatrix section. Generatrix sections 1 to 8 are divided at 45° intervals.

[0048] Step 2: Acquire the actual blank process state. By mounting the part in the rectangular coordinate system (XYZ), laser scanning of the outer and inner surfaces is performed on the machine to acquire the surface point cloud. Through continuous smooth fitting, the inner and outer surfaces are fitted and imported into this coordinate system, completing the acquisition of the actual blank process state.

[0049] Step 3: Compare the actual blank with the theoretical busbar offset. Figure 3 shows the busbar section parameter representation, with busbar sections 1 to 8 compared. The section Z1-O-X1 is the generatrix section 1, the curve La is the actual outer surface after the blank is formed; the curve Lb is the actual inner surface after the blank is formed; the curve Lc is the theoretical inner surface of the product; △h is the thickness distribution of the actual blank along the normal line, which is a gradual value from the small end to the large end; △S is the thickness difference between the actual inner surface Lb and the theoretical inner surface Lc along the normal line, which is above when Lc deviates outward and below when it deviates inward; La(xan, zan), Lb(xbn, zbn), Lc(xcn, zcn), etc. are points on the corresponding curves, and the intersection of the curves is the common point, as shown in the accompanying drawings Lc4 and Lb4; S(bc-n) (n=1, 2, 3..) is the area of ​​the intersection of Lb and Lc, which represents the offset set, such as S(bc-1) and S(bc-2) are schematic diagrams of the upper offset and lower offset respectively;

[0050] f Lb (x) is the internal surface equation of the actual busbar section, f Lc (x) is the cross-sectional equation of the theoretical model busbar. The busbar is continuous after forming. When f Lb (x)>f Lc (x), the blank is offset toward the outside, and when f Lb (x)<f Lc (x), the blank is offset inward; when f Lb (x) = f Lc (x) is the point where the two points coincide (x gn ,y gn ), divide it by the common points, and solve the values ​​of the upper offset and the lower offset. Upper offset Bottom offset When P tends to 0, the overall deviation is minimal; when P>0, the overall deviation is upward; when P<0, the overall deviation is downward.

[0051] According to busbar sections 1 to 8, the above offset values ​​are calculated and compared respectively.

[0052] As shown in Figure 4, according to the product process characteristics, the characteristic processing areas are distributed as 4-1, 4-2 to 4-m. According to the calculation relationship between the actual blank busbar section and the theoretical model busbar section in Figure 3, the characteristic processing areas 4-1, 4-2 to 4-m are matched with the actual blank busbar.

[0053] As shown in Figure 5, after the product processing features 4-1, 4-2 to 4-m in Figure 4 correspond to the distribution of the busbar section area, the local areas in 4-1, 4-2 to 4-m are sequentially planned, and the grid processing of the busbar section area is sequentially planned from 5-1, 5-2 to 5-m.

[0054] Step 4: Complete the structural feature-based machining area evaluation guidance. Figure 8 shows the local mesh feature cutting thickness in the direction of the generatrix section 1; 8-0 is the local high-rib mesh to be machined below the generatrix section; 8-1 is the cutting depth △h1 at the small end of the mesh; 8-2 is the actual inner profile surface; 8-3 is the bottom surface distribution of the mesh to be machined, and its distance from 8-2 is a certain value δ; 8-4 is the final remaining skin wall thickness δ, which is a given thickness; 8-5 is the cutting depth △h2 at the large end of the mesh; 8-6 is the blank thickness distribution △mn; 8-7 is the outer surface distribution of the mesh to be machined.

[0055] According to the thickness δ=3mm requirement of uniform thickness processing, the allowance removal of each generatrix section is different; the area to be removed in each feature area is K. Taking H1 in Figure 8 as an example, the cutting depth at the small end is △h1, and the large end is △h2, which is a variable cutting thickness; According to the first feature removal area shown in Figure 3, Total removal area on the busbar Local feature removal rate The evaluation index used to characterize the removal of a single feature on the section surface, the overall removal evaluation of the busbar is

[0056] According to the processing requirements of equal thickness 3mm, complete the resection evaluation calculation of busbar section 1 to busbar section 8.

[0057] Step 5: Complete the overall processing plan based on the busbar offset for busbar sections 1 to 8. According to the calculation results in step 4, compare the actual blank of each section with the theoretical busbar offset. Mn is the characterization of the cutting variation allowance on busbar section m. The cutting variation margin of each cutting surface m is compared to obtain the size ranking of Mm, as shown in Figure 4. The distribution of Mm from large to small is the overall path planning order of the cutting generatrix section.

[0058] Step 6: Complete the local path planning on the busbar section. According to the processing sequence of the busbar section, compare the local feature cutting variation allowance Kn'. The distribution of Kn' from large to small is the local path planning sequence of the selected busbar section.

[0059] Step 7: Perform overall machining and support adjustment. Following the steps in step 5, perform overall path machining. Based on the overall installation, the adjustable movable support head is driven to the center of the cutting area according to the distribution of Mm on the generatrix section and the machining path planning. The pneumatic clamping force is adjusted based on the local cutting rate Kn' to achieve stable cutting under variable cutting thickness. Sensors 7-8 detect rigidity and deformation during machining, further compensating for support and clamping forces to achieve reliable feature cutting.

[0060] The blank is installed vertically on the 6-1 bottom support area to ensure flatness and complete the large end fixation. After fixation, non-contact measurement of the blank's outer and inner surfaces is carried out. Data import and surface fitting are completed in the XYZ coordinate system to obtain the actual blank process model.

[0061] On the 6-2 busbar support area, according to the actual blank reference, complete the 7-2 adjustable auxiliary support screws arranged at intervals to ensure the overall rigidity of the product;

[0062] In the local processing area, the 6-3 movable support mechanism is used, on which two linked and controllable movable support heads are arranged. They move on the 7-1 busbar support area slide in the 6-2 busbar support area, and combined with the 7-6 movable support head, under the constraints of the 6-3 movable support mechanism and the 6-2 busbar support area, precise support of the actual inner surface area is achieved. The 7-3 movable support mechanism is combined with the 7-4 movable support mechanism slide, and the 7-5 multi-directional movable head supports the 7-6 movable support head; the 7-5 multi-directional movable head meets the precise fixation and rigidity requirements under different bending angles; the 7-6 movable support head includes the 7-7 flexible support pad (using pneumatic clamping to achieve flexible clamping under adjustable support force), the 7-8 sensor (meeting the support force and gap real-time monitoring), and the 7-9 flexible support head (an edge arc structure that meets the overall support requirements).

[0063] As the excess is removed and different features are processed in place, under the adjustable clamping, the entire part undergoes a controllable deformation in the generatrix section direction and evenly releases complex stresses, achieving deformation increment control for the entire product processing. The overall deformation increment is less than 3mm. When the overall deformation is detected to be too large, steps 3 to 7 are repeated to complete the dynamic adjustment of the processing path.

[0064] Step 8: Carry out local processing and deformation compensation.

[0065] ① Based on the actual state of the blank, grid processing is carried out under the initial adjustable support and processing path position; as the processing progresses, in addition to deformation along the generatrix section, large-scale processing will cause a certain degree of distortion and offset in the circumferential direction. The 7-8 sensor is used to monitor the sliding deformation of the contact surface of the 7-6 movable support head along the circumferential direction during the processing process, and the distance value is extracted as △L. When △L ≥ 2mm (exceeding the side roughing allowance), the support tooling reliability is readjusted, and the preparation process from the first step to the sixth step is completed again;

[0066] ② As shown in Figure 9, △AA'BB' is the offset of the side wall after roughing, and the offset along the circumference of roughing is △L (which can be equivalent to △BB'). The allowance after roughing the side wall is set to D = 2mm. The increase of △L is observed during the cutting process. When △L = D is the limit value, the allowance D at this time is first reduced to increase the margin. The range is reduced to 1-1.5mm. At the same time, the entire machining tool path moves L' = △LD in the direction of the △L deformation circle. When D > △L, the value during machining directly meets the compensation requirements.

[0067] ③ Perform fine machining according to the method in ② to achieve the local grid distortion processing. At the same time, according to the processing planning path based on the busbar offset, the entire product grid feature is accurately processed. The above method solves the deformation control problems such as the overall deformation increment control, reliable support and local deformation compensation of the 3800mm ellipsoid part, meeting the problem of efficient CNC machining and deformation control of the product. The single process preparation time is reduced by 4 hours, with high accuracy. Finally, all dimensions and deformations meet the technical indicators. The above support method, path planning method, measurement and support, etc. of the present invention are integrated through the software and hardware system and can be directly used by process personnel for scheduling in CNC machining.

[0068] The method provided by the present invention completes the overall processing, local processing deformation control and adjustable clamping of large and complex ellipsoidal parts under complex stress states and allowance distribution, effectively improving the product processing quality and guidance. Through the integration of the method and support control hardware and software, it can be used efficiently and conveniently; the technical system of the present invention can not only be used in the processing of large and complex ellipsoidal parts, but also is suitable for the processing planning of other complex spatial curved surface components to meet the requirements of high-performance processing of products.

[0069] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A deformation control method for large and complex ellipsoidal parts machining based on dynamic cutting planning, characterized in that: The steps include: S1. Initially clamp the blank part, build the machining coordinate system, complete the non-contact measurement of the inner and outer surface of the blank part and the reference surface fitting, and complete the generatrix section division; S2. Complete the comparison of each theoretical section with the measured section in the same coordinate system, decompose the product features, complete the cutting evaluation of the processing area based on the generatrix section, and guide the overall processing route planning and local processing route planning; S3, overall processing and support adjustment: Based on path planning and machinable margin, use the adjustable support device to complete the parts clamping based on dynamic adjustment and stable cutting under variable cutting thickness; S4, compensation processing after high-rib feature distortion: the rough machining along the circumference offset is △L, the side wall rough machining allowance after setting is D, and the increase of △L is observed during the cutting process; when △L=D is the limit value, first reduce the value of the allowance D at this time to increase the margin; at the same time, the overall machining tool path trajectory moves L'=△LD in the direction of the △L deformation circle; and when D>△L, the value during machining directly meets the compensation requirements; S5. Use the relationship between the force and posture of the dynamic support area to further correct the error and achieve accurate processing compensation of the mesh after local distortion.

2. According to claim 1, a large complex ellipsoidal part machining deformation control method based on dynamic cutting planning is characterized by: In the step S1, a spatial rectangular coordinate system XYZ is established with the bottom surface of the large end of the part as a reference and the center of the bottom surface as the center of a circle.

3. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 1 is characterized in that: In the step S2, the parameter characterization of the section of the blank part in the actual process state and the section of the generatrix of the theoretical model in the same coordinate system is completed; and the offset comparison of the actual blank part relative to the generatrix of the theoretical model is completed.

4. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 3 is characterized in that: In the step S2, curve La is the actual outer surface after the blank is formed; curve Lb is the actual inner surface after the blank is formed; curve Lc is the theoretical inner surface of the product; △h is the thickness distribution of the actual blank along the normal line, which is a gradual value from the small end to the large end; △S is the thickness difference between the actual inner surface Lb and the theoretical inner surface Lc along the normal line, which is at the top when Lc deviates outward and at the bottom when it deviates inward; La(xan, zan), Lb(xbn, zbn), Lc(xcn, zcn) are points on the corresponding curves, and the intersection of the curves is the common point, S(bc-n) (n=1, 2, 3..) is the area of ​​the intersection of Lb and Lc, which represents the offset set, such as S(bc-1) and S(bc-2) are schematic diagrams of the upper offset and the lower offset respectively; f Lb (x) is the internal surface equation of the actual generatrix section, f Lc (x) is the section equation of the generatrix of the theoretical model. The generatrix is ​​continuous after forming. When f Lb (x)>f Lc (x), the blank is offset toward the outside, and when f Lb (x)<f Lc (x), the blank is offset inward; when f Lb (x) = f Lc (x) is the point where the points coincide (x gn ,y gn ), divide it by the common points, and solve the values ​​of the upper offset and the lower offset. Upper offset Bottom offset When P tends to 0, the overall deviation is minimal; when P>0, the overall deviation is positive; P < 0, overall downward shift; According to the busbar section, the above-mentioned offsets are calculated and compared respectively.

5. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 1 is characterized in that: In step S2, the area to be removed in each characteristic region is K, the cutting depth at the small end is △h1, and the cutting depth at the large end is △h2, which is a variable cutting thickness; The first feature removal area Total removal area on busbar Local feature removal rate It is used to characterize the resection evaluation index of a single feature on the section. The overall resection evaluation of the busbar is According to the equal thickness processing requirements, complete the cutting evaluation calculation of the busbar section.

6. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 5 is characterized in that: The actual blank of each cut surface is compared with the theoretical generatrix offset. Mn is the representation of the cutting variation margin on the generatrix cut surface m. Compare the cutting variation margin of each cutting surface m to obtain the size ranking of Mm. The distribution of Mm from large to small is the overall path planning order of cutting the generatrix cutting surface. The local feature cutting variation margin Kn' is compared, and the distribution of Kn' from large to small is the local path planning order of the selected generatrix section.

7. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 1 is characterized in that: In the step S3, the adjustable support device includes a bottom support area, a busbar support area and a movable support mechanism, the busbar support area is provided with a busbar support area slide groove, the bottom support area is provided with a movable support mechanism slide groove, the movable support mechanism includes a movable support movable mechanism, a multi-directional movable head and a movable support head, the movable support movable mechanism is arranged in the movable support mechanism slide groove, the movable support head is arranged in the busbar support area slide groove, the movable support movable mechanism and the multi-directional movable head are connected by a support rod, and the multi-directional movable head and the movable support head are connected by a support rod.

8. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 7 is characterized in that: The movable support head includes a flexible support head, a flexible support pad and a sensor. The flexible support pad is arranged on a side of the flexible support head away from the slide groove of the busbar support area. The sensor is used to monitor the support force and the gap / sliding displacement in real time.

9. The method for controlling deformation of large complex ellipsoidal parts based on dynamic cutting planning according to claim 7 or 8, characterized in that: The busbar supporting area is provided with adjustable auxiliary supporting screws.

10. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 1, characterized in that: In step S3, according to the distribution of cutting variation margin on the generatrix section and the processing path planning, the adjustable support device is driven to be linked to the center of the cutting area, and the pneumatic clamping force is adjusted in combination with the local cutting rate index to achieve stable cutting under variable cutting thickness.

11. The deformation control method for machining large complex ellipsoidal parts based on dynamic cutting planning according to claim 1, characterized in that: In step S4, when ΔL exceeds the rough machining allowance of the side surface, the adjustable support device is readjusted and the planning and machining are completed again.

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