Spaceflight profile frame multi-point stretch bending springback compensation method and shaping template

Abstract

This invention discloses a method for compensating springback during multi-point bending of aerospace profile frames and a shaping template. The shaping template needs to be used in conjunction with a multi-point bending mold and includes a master template and several sub-templates. The master template is provided with master template positioning holes and master template notches. The sub-templates are provided with sub-template bosses. The springback compensation method includes the following steps: designing and manufacturing an initial shaping template, assembling the shaping template and adjusting the mold, multi-point bending forming, deviation measurement, springback compensation profile design, re-preparation of the shaping template and sub-templates, re-shaping, and re-forming. Through multiple iterations of "shaping template design - mold shaping - forming - deviation measurement - springback compensation", the complex springback compensation problem is transformed into a repeatable template shaping problem.

Description

Technical Field

[0001] This invention relates to the field of aerospace profile frame forming technology, specifically to a multi-point bending springback compensation method and a shaping template for aerospace profile frames. Background Technology

[0002] In the aerospace field, profile frames are mostly 180° large central angle structures, and are usually formed using stretch bending or roll bending processes. Roll bending has higher flexibility but lower forming efficiency and poorer profile surface quality; stretch bending has higher forming efficiency but lower flexibility, and often uses integral steel molds or insert-type steel molds, requiring multiple mold repairs to adjust the profile, making it difficult to meet the flexible shaping requirements within a certain forming radius range.

[0003] Multi-point stretch bending forming methods can achieve flexible shaping within a certain forming radius, but traditional multi-point stretch bending forming equipment and systems are costly. Although existing technologies have proposed flexible multi-point stretch bending mold structures for aerospace profile frames, without the support of CNC shaping mechanisms and systems, it is difficult to complete the precise shaping operation of the predetermined surface by relying solely on manual labor.

[0004] Meanwhile, some literature has studied the springback compensation direction and springback compensation algorithm from the perspectives of theoretical analysis and numerical simulation. However, for multi-point stretch bending forming with non-uniform radial shaping method, there is still a lack of experimentally based and production-adapted springback compensation methods. The production site lacks simple and reliable shaping templates and supporting springback compensation methods for guidance.

[0005] Therefore, it is necessary to provide a simple, versatile, and easy-to-operate shaping template, as well as a springback compensation method suitable for multi-point bending processes with non-uniform radiation shaping, in order to improve the surface accuracy and production efficiency of multi-point bending forming of aerospace profile frames. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for multi-point bending springback compensation of aerospace profile frames and a shaping template.

[0007] To achieve the above objectives, the present invention employs the following technical solutions:

[0008] A shaping template for multi-point bending of aerospace profile frames, wherein the shaping template needs to be used in conjunction with a multi-point bending mold, and includes a master template and several sub-templates;

[0009] The master template is provided with master template positioning holes that cooperate with the template positioning pins on the multi-point bending die, so that the master template can be reliably positioned on the multi-point bending die; the master template has multiple master template notches discretely distributed along the length direction of the profile.

[0010] The sub-template is provided with a sub-template boss that mates with the notch of the mother template. Through the engagement of the sub-template boss with the notch of the mother template, the sub-template can be quickly and accurately positioned on the mother template. The positioning arc surface of the sub-template mates with the positioning arc surface of the mother template, and the working arc surface of the sub-template mates with the arc surface of the second forming block of the multi-point bending die. Thus, during the shaping process, the envelope surface of the die surface is defined by the envelope surface of the working arc surface of the sub-template.

[0011] A method for multi-point bending springback compensation of aerospace profile frames includes the following steps;

[0012] Step S1, Design and manufacture the initial shaping template: This also includes the following steps;

[0013] Step S11: Draw the initial mold surface curve;

[0014] Step S12: Design the master template;

[0015] Step S13: Design sub-templates:

[0016] Step S14: Process the template and mark it;

[0017] Step S2: Assembly of the shaping template and shaping of the mold;

[0018] Step S3, Multi-point stretch bending forming: The profile frame is formed by multi-point stretch bending using conventional processes;

[0019] Step S4, Deviation Measurement: Measure the surface deviation of the profile frame along each radial shaping direction after multi-point bending. If the requirements are met, fix the current bending process and use the current master template and sub-template as the final template for batch production; otherwise, proceed to the next step.

[0020] Step S5, Springback Compensation Surface Design: This specifically includes the following steps:

[0021] Step S51, Compensation value calculation: Multiply the deviation values ​​at each point by a certain compensation coefficient to obtain the compensation value for each discrete point;

[0022] Step S52: The compensation values ​​are superimposed on the prototype envelope curve 82h along the radial shaping direction, i.e., the central axis 82g of the T-groove, to obtain several correction points. The correction points should be symmetrical left and right. If they are not symmetrical, the average value is taken.

[0023] Step S53, Surface Fitting. Use spline curves to sequentially fit each correction point, ensuring at least G1 continuity (i.e., the tangent direction of the curve is continuous at the connection point);

[0024] Step S6: Based on the compensation surface obtained in step S5, re-prepare the sub-pattern, design and process the new sub-pattern with reference to steps S13 and S14, and repeat steps S2 to S5 until the surface deviation meets the requirements. The corresponding master pattern and sub-pattern are used as the finalized pattern for mass production.

[0025] The present invention has the following beneficial effects:

[0026] 1. By designing a shaping template structure consisting of a master template and several sub-templates, flexible shaping of the envelope surface of a multi-point bending mold can be achieved without adding an expensive CNC shaping mechanism. The structure is simple, versatile, and saves materials.

[0027] 2. By cooperating with the second basic unit of the multi-point bending die through the adjustment template, the die surface can be adjusted intuitively and visually by adjusting it one by one from the middle of the die to both sides. The adjustment method is easy to understand and easy to operate, and is suitable for application on the production site.

[0028] 3. Based on the actual measurement results of the surface deviation after bending, the deviation value is uniformly scaled by the compensation coefficient and superimposed on the prototype envelope curve along the radial adjustment direction. Combined with left and right symmetry processing and spline fitting, a springback compensation surface suitable for actual production is formed. The compensation method is reasonable and accurate, which can effectively improve the surface accuracy of the profile frame after multi-point bending.

[0029] 4. Through multiple rounds of template design and springback compensation iteration, the complex springback compensation problem can be transformed into a repeatable template adjustment problem, which is convenient for promotion and application in production. Attached Figure Description

[0030] Figure 1 This is a flowchart of a multi-point bending springback compensation method for aerospace profile frames.

[0031] Figure 2 This is a schematic diagram of a multi-point bending template structure for aerospace profile frames.

[0032] Figure 3 This is a schematic diagram of the use of a multi-point bending template for aerospace profile frames (I).

[0033] Figure 4 This is a schematic diagram (II) of the use of a multi-point bending adjustment template for aerospace profile frames.

[0034] Figure 5 This is a magnified view of a typical part of the sub-template drawing of a multi-point bending adjustment template for aerospace profile frames.

[0035] Figure 6 This is a schematic diagram of the overall structure of a flexible multi-point bending mold for aerospace profile frames.

[0036] Figure 7 This is a schematic diagram of the base structure of a flexible multi-point bending mold for aerospace profile frames.

[0037] Figure 8 This is a schematic diagram of the first basic unit structure of a flexible multi-point bending die for aerospace profile frames.

[0038] Figure 9 This is a schematic diagram of the shaping component structure of a flexible multi-point bending mold for aerospace profile frames.

[0039] Figure 10 This is a schematic diagram of the cross-sectional structure of a shaping component for a flexible multi-point bending die for aerospace profile frames.

[0040] Figure 11 This is a schematic diagram of the forming component structure of a flexible multi-point bending die for aerospace profile frames.

[0041] Figure 12 This is a schematic diagram of the cross-sectional structure of a forming component of a flexible multi-point bending die for aerospace profile frames.

[0042] In the diagram: 1-Base, 2-First basic unit, 3-Second basic unit, 4-Template positioning pin, 11-Positioning pin hole, 12-Groove, 13-T-slot, 14-T-slot step, 15-Part theoretical line, 21-First forming block, 22-First pressing block, 31-Shaping assembly, 32-Forming assembly, 311-Lead screw, 312-Cover plate, 313-Baffle, 321-Guide block, 322-Limiting pin, 323-Second forming block, 324-Second pressing block, 32 5-Retaining ring, 8-Shaping template, 81-Mother template, 82-Child template, 81a-Mother template notch, 82a-Child template boss, 82b-Second straight line, 82c-First multi-segment arc, 82d-Third intersection point, 82e-First straight line, 82f-First intersection point, 82g-T-groove center axis, 82h-Shaped envelope curve, 82i-First offset arc, 82j-First circle, 82k-Second intersection point, 82l-Second offset arc, 811-Mother template positioning hole. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings.

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0045] Example 1:

[0046] like Figure 2As shown, a multi-point bending template 8 for aerospace profile frames is provided. The template 8 needs to be used in conjunction with a multi-point bending mold and includes a mother template 81 and several sub-templates 82.

[0047] The master template 81 is provided with a master template positioning hole 811 that cooperates with the template positioning pin 4 on the multi-point bending die, so that the master template 81 can be reliably positioned on the multi-point bending die; multiple master template notches 81a are discretely distributed on the master template 81 along the length direction of the profile.

[0048] The sub-template 82 is provided with a sub-template boss 82a that mates with the notch 81a of the mother template. Through the engagement of the sub-template boss 82a with the notch 81a of the mother template, the sub-template 82 can be quickly and accurately positioned on the mother template 81. The positioning arc surface of the sub-template 82 mates with the positioning arc surface of the mother template 81, and the working arc surface of the sub-template 82 mates with the arc surface of the second forming block of the multi-point bending die. Thus, during the shaping process, the envelope surface of the die surface is defined by the envelope surface of the working arc surface of the sub-template 82.

[0049] The master template 81 has a 1 / 2 structure relative to the entire mold surface. The width and depth of the master template notch 81a are the same, and the width of the master template notch 81a is greater than the upper width of the mold T-slot. The angle of the master template notch 81a is the same as the angle of the T-slots radiating along the upper edge of the multi-point bending mold, so as to facilitate the matching and shaping of the sub-template 82 with the second basic unit of the multi-point bending mold.

[0050] The working arc surface of the sub-template 82 is an inner arc surface. The envelope surface of the working arc surfaces of all sub-templates 82 constitutes the envelope surface of the mold surface, and the working arc surface of each sub-template 82 is inscribed in the envelope curve of the mold surface. Among them, the width, depth and angle of the sub-template boss 82a are consistent with the width, depth and angle of the corresponding mother template notch 81a.

[0051] Sub-templates 82 can be set in multiple groups according to different predetermined surfaces. Each group of sub-templates 82 corresponds to a predetermined surface to meet the needs of different forming radii and different target surfaces.

[0052] Both the mother template 81 and the daughter template 82 are plate-shaped structures, which are processed by CNC equipment. The daughter template 82 is provided with identification marks for marking the predetermined surface, so as to facilitate the identification and assembly of daughter templates 82 with different predetermined surfaces.

[0053] A flexible multi-point bending die for aerospace profile frames includes a base 1, a first basic body unit 2, several sets of second basic body units 3, and a template positioning pin 4.

[0054] The base 1 has grooves 12, positioning pin holes 11, and T-shaped grooves 13 on its upper surface. The T-shaped grooves 13 are distributed on both sides of the grooves 12, and each T-shaped groove 13 points to a different center. Each T-shaped groove 13 has a concave T-shaped groove step 14 at the end away from the center.

[0055] The first basic unit 2 includes a first forming block 21 and a first pressing block 22 connected by hexagon socket screws, and the first forming block 21 and the first pressing block 22 are installed inside the groove 12 by hexagon socket screws.

[0056] Each group of second basic body units 3 includes a shaping component 31 and a forming component 32; by rotating the shaping component 31, the corresponding forming component 32 can be driven to move radially along the T-groove 13, thereby adjusting the position of each second basic body unit 3 on the base 1, so that the first basic body unit 2 and several second basic body units 3 together form a mold envelope surface suitable for the bending and forming of aerospace profile frames.

[0057] The forming component 32 includes a guide block 321. The lower part of the guide block 321 is a T-shaped structure that slides with the T-groove 13, and the upper part is a cylindrical structure, so that the forming component 32 can slide along the T-groove 13 and rotate around the cylindrical axis of the guide block 321. A second forming block 323 is sleeved on the outer side of the cylindrical section on the guide block 321. A second pressure block 324 is connected to the upper end of the second forming block 323 by screws. A retaining ring 325 is connected to the upper end of the guide block 321 by screws, and the lower end of the retaining ring 325 can press down on the second forming block 323 to prevent the second forming block 323 and the second pressure block 324 from moving out along the direction of the guide block 321, but retaining a gap for rotation.

[0058] The shaping component 31 includes a cover plate 312 and a baffle 313 that are fixed together on the T-shaped groove step 14 by internal hexagon screws. One end of a lead screw 311 is rotatably installed in the receiving cavity formed between the cover plate 312 and the baffle 313. The other end of the lead screw 311 is threadedly connected to the guide block 321. By rotating the lead screw 311, the corresponding forming component 32 can be driven to move radially along the T-shaped groove 13, thereby achieving the purpose of adjusting the position of each second basic unit 3 on the base 1.

[0059] The upper surface of the base 1 is also engraved with several theoretical lines 15 of the part arranged along the envelope surface of the aerospace profile to be formed. The projection of the theoretical lines 15 on the base 1 is tangent to the projection of the first forming block 21 on the base 1. This is used to observe the springback of the part during the bending process and as a reference for shaping.

[0060] A limiting pin 322 is provided between the guide block 321 and the second forming block 323. The limiting pin 322 is used to restrict the second forming block 323 and the second pressing block 324 so that the side of its forming arc surface always faces the part to be formed.

[0061] The working surfaces of the first forming block 21 and the second forming block 323 that contact the aerospace profile frame parts to be formed are both arc surfaces. The radius of the arc surface of the first forming block 21 is smaller than the forming radius of the corresponding part. The radius of the arc surface of the second forming block 323 is set to be no less than half of the radius of the largest part that the mold can form, and no greater than the radius of the smallest part that the mold can form, so that different radii of mold envelope surfaces can be formed by adjusting the position combination of each second basic body unit 3.

[0062] Both the first pressure block 22 and the second pressure block 324 are provided with inclined guide surfaces facing the mold cavity, which are used to guide the parts into the mold cavity and limit the deformation of the parts in the height direction when warping occurs after bending and heat treatment; wherein, the bottom surface of the second pressure block 324 is higher than the height of the profile used in the aerospace profile frame to be formed, so as to avoid scratching the surface of the parts during bending and clamping.

[0063] The number and distribution of T-slots 13 are matched with the size of the second basic unit 3 and the radius range of the part to be formed. Under the premise of ensuring that each second basic unit 3 does not interfere with each other during the shaping process, the extension direction of each T-slot 13 is arranged as close as possible to the center of the mold envelope surface so as to form a radially distributed multi-point forming unit.

[0064] The template positioning pin 4 is inserted into the positioning pin hole 11 and is used to position and install the adjustment template during the adjustment stage. It is used in conjunction with the theoretical line 15 of the part. After the adjustment is completed, the template positioning pin 4 and the adjustment template can be removed. The mold envelope surface formed by the adjustment is retained for the bending and forming of the 180° large central angle aerospace profile frame, making the adjustment more accurate.

[0065] Example 2:

[0066] like Figure 1 , Figure 3 , Figure 4 As shown, a multi-point bending springback compensation method for aerospace profile frames includes the following steps;

[0067] Step S1, Design and manufacture the initial shaping template 8: Draw the graphic of the initial shaping template 8 in CAD software, which also includes the following steps;

[0068] Step S11: Draw the initial mold surface curve;

[0069] Step S111: Obtain the initial mold profile: The initial mold profile is designed based on the numerical simulation results or the springback ratio from production experience (the initial mold profile is symmetrical from left to right; if the simulation results are not symmetrical, take the average value to make it symmetrical from left to right).

[0070] Step S112: Fit the envelope curve of the two-dimensional projection of the initial mold surface to obtain the mold envelope curve 82h (the mold envelope curve 82h is a spline curve, which is symmetrical on both sides and at least ensures G1 continuity).

[0071] Step S12: Design the master template 81 (this step can be skipped if there is a master template 81); the master template 81 has a 1 / 2 structure relative to the entire mold surface, and is designed with master template positioning holes 811 that are coordinated with the template positioning pins 4. The width and depth of the notches at all points on the master template 81 are consistent, and the width of the notch 81a on the master template is wider than the upper part of the mold T-slot, and the notch angle is consistent with the T-slots that are radially distributed on the mold.

[0072] Step S13: Design sub-template 82. The width, depth, and angle of the sub-template boss 82a are consistent with the corresponding notch 81a of the parent template. The envelope of the working arc surface of all sub-templates 82 is the envelope of the mold surface, that is, the working arc surface of the sub-template 82 is inscribed in the mold envelope curve 82h. The method for drawing sub-template 82 is described in [link to drawing instructions]. Figure 6 ,

[0073] Step S14: Process and mark the templates. Use CNC equipment to cut the materials to obtain the master template 81 and several sub-templates 82;

[0074] Step S2, assembly of shaping template 8 and mold shaping; specifically, it also includes the following steps:

[0075] Step S21: Clamp the master template 81. Assemble the master template 81 onto one side of the multi-point bending mold using two template positioning pins 4, and perform distributed clamping (clamping can be done using clamping materials with high density and small volume, such as clamps or iron blocks).

[0076] Step S23: Assemble sub-pattern 82. Assemble the marked sub-pattern 82 in order from the middle of the multi-point bending mold outwards, ensuring proper fit;

[0077] Step S24: Multi-point bending die adjustment. By operating the multi-point bending die, the arc surface of the second forming block 323 of the multi-point bending die is made to fit with the arc surface of the sub-template 82. The position of the second basic unit 3 of the multi-point bending die is adjusted from the middle of the die outwards. After the second basic unit 3 on one side is adjusted, the adjustment template 8 is flipped over to adjust the second basic unit 3 on the other side. After the adjustment is completed, the clamping object, the adjustment template 8 and the template positioning pin 4 are removed.

[0078] Step S3: Multi-point stretch bending and forming.

[0079] The profile frame is formed by multi-point bending using conventional bending equipment.

[0080] Step S4, Deviation Measurement. Measure the surface deviation of the profile frame along each radial shaping direction after multi-point bending. If the requirements are met, fix the current bending process and use the currently used master template 81 and sub-template 82 as the final templates for batch production; otherwise, proceed to the next step.

[0081] Step S5, Springback Compensation Surface Design. This specifically includes the following steps:

[0082] Step S51: Compensation value calculation. Multiply the deviation values ​​at each location by a certain compensation coefficient to obtain the compensation value for each discrete point (the compensation coefficient is related to the specific structure of the mold, the bending process, the profile cross-section, and the mechanical properties. It can be explored based on multiple bending results. If the deviation direction at the same measurement position is the same as before after bending again after compensation, the compensation coefficient should be increased; otherwise, the compensation coefficient should be decreased).

[0083] Step S52: The compensation values ​​are superimposed on the prototype envelope curve 82h along the radial shaping direction, i.e., the central axis 82g of the T-groove, to obtain several correction points. The correction points should be symmetrical left and right. If they are not symmetrical, the average value is taken.

[0084] Step S53: Surface Fitting. Use spline curves to sequentially fit each correction point, ensuring at least G1 continuity;

[0085] Step S6: Repeat steps S13 to S5 until the master template 81 and the sub-template 82 are used as the finalized templates for mass production.

[0086] Example 3:

[0087] Based on Example 2, further explanation is given regarding step S13 and the design of sub-pattern 82, such as... Figure 5 As shown

[0088] Specifically, the following steps are included:

[0089] Step S13: Design sub-template 82. The width, depth, and angle of the sub-template boss 82a are consistent with the corresponding notch 81a of the parent template. The envelope of the working arc surface of all sub-templates 82 is the envelope of the mold surface, that is, the working arc surface of the sub-template 82 is inscribed in the mold envelope curve 82h. The method for drawing sub-template 82 is described in [link to drawing instructions]. Figure 6 This includes the following steps:

[0090] Step S131: Draw the center axis 82g of each T-slot on the upper surface of the mold.

[0091] Step S132: Offset the mold surface. Offset the mold envelope curve 82h inward by a first distance to obtain the first offset arc 82i, where the first distance is the minimum distance between the axis of the guide block 312 and the arc surface of the second forming block 323; Offset the mold envelope curve 82h inward by a second distance to obtain the second offset arc 82l, where the second distance is the radius of the arc surface of the second forming block 323;

[0092] Step S133: Draw the normal. The central axis 82g of each T-groove intersects the first offset arc 82i at the first intersection point 82f. At each first intersection point 82f, draw the first straight line 82e, ensuring that the first straight line 82e is perpendicular to the first offset arc 82i at the first intersection point 82f, and ensuring that the first straight line 82e intersects the second offset arc 82l at the second intersection point 82k.

[0093] Step S134: Draw the first circle 82j. Using each second intersection point 82k as the center and the second distance as the radius, draw several first circles 82j.

[0094] Step S135: Trim and draw the second straight line 82b. Trim the intersecting first circles 82j to form several third intersection points 82d, and several arcs to form the first multi-segment arc 82c. Draw the second straight line 82b at each third intersection point 82d, ensuring that the second straight line 82b intersects the shape envelope curve 82h perpendicularly.

[0095] Step S136: Trim redundant line features to obtain the CAD drawing of sub-pattern 82;

[0096] Through the above three implementation methods, the present invention provides a complete springback compensation and shaping template application scheme for multi-point stretch bending forming of non-uniform radiation shaping method, which can effectively improve the surface accuracy and production efficiency of multi-point stretch bending forming of aerospace profile frames.

[0097] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A shaping template for multi-point bending of aerospace profile frames, wherein the shaping template needs to be used in conjunction with a multi-point bending mold, characterized in that: The multi-point bending die includes a master template and several sub-templates, and includes a base, a first basic body unit, several sets of second basic body units, and template positioning pins. The upper surface of the base is provided with grooves, positioning pin holes, and T-shaped grooves. The first basic unit includes a first forming block and a first pressing block connected by hexagon socket screws, and the first forming block and the first pressing block are installed inside the groove by hexagon socket screws. Each group of second basic body units includes a shaping component and a forming component; the forming component includes a guide block, the lower part of the guide block is a T-shaped structure that slides with the T-slot, the upper part is a cylindrical structure, a second forming block is sleeved on the outer side of the cylindrical section on the guide block, a second pressure block is connected to the upper end of the second forming block by a screw, a retaining ring is connected to the upper end of the guide block by a screw, and the lower end of the retaining ring can press down the second forming block; The master template is provided with master template positioning holes that cooperate with the template positioning pins of the multi-point bending mold, and multiple master template notches are discretely distributed along the length direction of the profile on the master template. The sub-template is provided with a sub-template boss that matches the notch of the mother template. The positioning arc surface of the sub-template matches the positioning arc surface of the mother template. The working arc surface of the sub-template matches the arc surface of the second forming block of the multi-point bending die.

2. The shaping template for multi-point bending of aerospace profile frames according to claim 1, characterized in that: The master template has a 1 / 2 structure relative to the entire mold surface. The width and depth of the notch in the master template are the same, and the width of the notch in the master template is greater than the upper width of the T-slot. The angle of the notch in the master template is the same as the angle of the T-slots radially distributed along the upper edge of the multi-point bending mold.

3. The shaping template for multi-point bending of aerospace profile frames according to claim 2, characterized in that: The width, depth, and angle of the sub-template boss are consistent with the width, depth, and angle of the corresponding mother template notch, and the working arc surface of the sub-template is an inner arc surface.

4. The shaping template for multi-point bending of aerospace profile frames according to claim 1, characterized in that: The sub-templates can be set in multiple groups according to different predetermined surfaces.

5. The shaping template for multi-point bending of aerospace profile frames according to claim 1, characterized in that: The sub-template is provided with identification marks for marking the predetermined surface.

6. A method for multi-point bending springback compensation of aerospace profile frames based on any one of the shaping templates described in claims 1-5, characterized in that: Includes the following steps; Step S1, Design and manufacture the initial shaping template: This also includes the following steps; Step S11: Draw the initial mold surface curve; Step S12: Design the master template; Step S13: Design sub-templates: Step S14: Process the template and mark it; Step S2: Assembly of the shaping template and shaping of the mold; Step S3, Multi-point stretch bending forming: The profile frame is formed by multi-point stretch bending using conventional processes; Step S4, Deviation Measurement: Measure the surface deviation of the profile frame along each radial shaping direction after multi-point bending. If the requirements are met, fix the current bending process and use the current master template and sub-template as the final template for batch production; otherwise, proceed to the next step. Step S5, Springback Compensation Surface Design: This specifically includes the following steps: Step S51, Compensation value calculation: Multiply the deviation values ​​at each point by a certain compensation coefficient to obtain the compensation value for each discrete point; Step S52: The compensation values ​​are superimposed along the radial shaping direction, i.e., the central axis of the T-groove, based on the prototype envelope curve to obtain several correction points. The correction points should be symmetrical left and right. If they are not symmetrical, the average value is taken. Step S53, Surface Fitting: Use spline curves to fit each correction point sequentially, ensuring at least G1 continuity, that is, the tangent direction of the curve is continuous at the connection point. Step S6: Based on the compensation surface obtained in step S5, re-prepare the sub-pattern, design and process the new sub-pattern with reference to steps S13 and S14, and repeat steps S2 to S5 until the surface deviation meets the requirements. The corresponding master pattern and sub-pattern are used as the finalized pattern for mass production.

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