A high-precision assembly frame skin negative pressure composite panel forming process

Abstract

This invention discloses a high-precision assembly frame skin negative pressure composite panel forming process, including: first, designing a three-dimensional orthogonal splicing frame mold; second, completing the design of the working panel, back panel, and edge banding strip, including segmentation and seam opening, and unfolding the cutting drawing; third, cutting the material according to the sequence of "segment boundary - positioning hole - marker point - stress joint", ensuring that the shape and position accuracy of the material meets ±0.1mm; next, completing the assembly and precision adjustment of the frame mold, so that the surface accuracy of the frame is better than 0.040mm; then, through positioning, lay-up, and adhesive application, performing negative pressure forming and curing of the panel; finally, bonding the edge banding strip, filling the stress gaps, polishing, and then performing surface spraying. This invention can achieve 10m 2 The above-mentioned ultra-large and complex panel forming process achieves a typical RMS accuracy better than 0.045mm. This invention is applicable to the manufacturing of small batches of complex curved, high-precision, ultra-large-sized reflective panels.

Description

Technical Field

[0001] This invention belongs to the field of reflector antenna manufacturing, specifically involving a high-precision assembly frame skin negative pressure composite panel forming process, which is particularly suitable for the forming requirements of ultra-large size high-precision complex curved surfaces (including non-analytical curved surfaces), and especially suitable for small-batch customization of high-precision reflector antennas. Background Technology

[0002] High-precision reflective panels are core components in microwave communications, radar, and stealth applications, commonly used in large-aperture communication antennas, radio telescopes, and compact test ranges. To meet testing requirements such as ultra-large sizes, ultra-wide bandwidths, and complex extreme operating environments, it is necessary to improve the utilization rate of the reflective surface aperture to reduce technical risks and production costs. Therefore, the engineering difficulty of high-precision panels is increasing, posing higher requirements and challenges to the design and manufacturing of complex high-precision panels.

[0003] Currently, common panel manufacturing and forming processes mainly include: skin and frame riveting forming, solid mold stretch forming, precision machining, surface metallization treatment of non-metallic composite substrates after machining, and sandwich panel flexible mold negative pressure forming. Based on the applicant's extensive research and practical experience, the existing technologies mainly have the following shortcomings: 1) Traditional skin and frame riveting forming processes are simple and low-cost, but do not meet high precision requirements (surface accuracy better than 10). -2 Application scenarios (mm); 2) Solid mold stretch forming accuracy can reach sub-millimeter level, but the mold cost is extremely high for small batch customization needs; 3) High machining accuracy, but long processing cycle and high processing cost; 4) Metallization treatment of composite material surface after machining requires special process equipment, long production cycle, complex process and high cost; 5) The sandwich panel flexible mold negative pressure forming process is mature, but it cannot meet the accuracy requirements of forming complex surfaces (including non-analytical curved surfaces) with local concave and convex transitions. At the same time, after the multi-layer adhesive sandwich structure is formed and demolded, there is internal stress and springback phenomenon. Especially under high temperature conditions, the adhesive layer softens, causing the panel to produce irreversible deformation. The sandwich panel structure has poor adaptability to high temperature environment. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a high-precision assembly frame skin negative pressure composite panel forming process, which achieves the technical goals required for complex surface panels, such as large size, complex non-analytical curved surface, high precision, and good environmental adaptability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-precision assembly frame skin negative pressure composite panel forming process is applicable to large-size complex curved surfaces, including non-analytical curved surfaces, and 10 -2Panel forming with millimeter-level precision requirements: The high-precision assembled frame mold skin negative pressure composite panel includes a frame mold, a working panel, a back panel, and edge sealing strips. It is bonded and formed on a high-precision vacuum negative pressure reference platform using room-temperature curing adhesive, including the following steps:

[0007] Step 1: Design a 3D orthogonal frame mold;

[0008] Step 2: Design the panel segmentation and cutting of each panel;

[0009] Step 3: Cutting the material: First, use a laser cutting machine to cut the material in the order of "outer frame - positioning hole - mounting hole - stress gap". The cutting shape and position accuracy error should be ≤0.1mm.

[0010] Step 4: Assemble the frame mold and adjust its precision;

[0011] Step 5: Apply negative pressure to the panel and allow it to cure naturally;

[0012] Step Six: Perform edge banding and panel surface treatment.

[0013] Further, step one includes:

[0014] 1.1) A plane perpendicular to the normal at the geometric center point of the working surface of the panel to be formed, and at a distance equal to the thickness of the selected frame model, is made in the direction close to the back plate.

[0015] 1.2) Calculate the equidistant surfaces of the working curved surface of the panel to be formed based on the thickness of the working panel to obtain the frame mold surface;

[0016] 1.3) Take the boundary of the frame mold surface and stretch it along the normal of the reference surface to the forming reference surface to obtain the boundary stretching surface; take the intersection of the boundary stretching surface and the forming reference surface to obtain the reference section; combine the frame mold surface, the boundary stretching surface and the reference section to obtain the closed panel three-dimensional envelope boundary.

[0017] 1.4) Based on the selected frame mold spacing and frame mold rib thickness, draw sketches of the center line positions of the transverse and longitudinal frame ribs on the forming reference plane, ensuring that the projection area of ​​the center line position sketch is larger than the projection range of the panel's three-dimensional envelope surface on the reference plane, wherein the frame mold rib thickness is above 3mm;

[0018] 1.5) The centerline position sketch is stretched along the normal of the forming reference plane to form a rib array. The three-dimensional envelope boundary is used as the dividing boundary. The internal part of the rib array is divided to obtain the overall digital model of the frame mold.

[0019] 1.6) Complete the design of the joints of longitudinal and transverse stiffeners, the mounting holes of corner fittings, the installation interfaces of the adjustment structure, and the positioning pins of the work panel;

[0020] 1.7) Take the projection of the middle section of each rib to generate the rib cutting diagram.

[0021] Furthermore, step two includes:

[0022] 2.1) In the design of the work panel segmentation and blanking, firstly, based on the principle of ensuring the accuracy of the central area, the work panel is segmented according to the material and processing capacity, and the segmentation position is determined. The total width of the segment gap is determined according to the gap thickness ratio of 0.3, and all segment gaps are open. Secondly, the position and length of the stress gap are determined through finite element simulation. The width of the stress gap is determined according to the gap thickness ratio of 0.2. The single panel after segmentation is not broken as a whole, and at least a connection area of ​​not less than 2mm is retained within every 400mm length of the stress gap. Next, the position of the work panel marker point is determined according to the optimization of minimizing deformation under working conditions, and a φ0.1mm circular hole is reserved. Then, the positioning square hole on the work panel is determined according to the position of the positioning hole pin on the rib, and its diameter is 0.1mm to 0.2mm larger on one side than the positioning hole pin on the rib. Next, the unfolded surface of the work panel is generated by surface unfolding. Then, the position of the φ1.0mm marker hole is determined on the unfolded surface with the center of the unfolded shape with the reserved φ0.1mm circular hole as the center. Finally, the blanking drawing of the work panel is generated by surface unfolding.

[0023] 2.2) In the design of back panel segmentation and blanking, firstly, after the edge of the reference section is reduced inward by 10mm, the back panel is segmented according to the material size while ensuring rigidity. It is required that the back panel segmentation line and the panel segmentation line should not coincide, but be orthogonal and staggered. The method of opening the gap is the same as in step 2.1). Secondly, the projection position of the working panel mark point on the back panel is determined according to the optimization of the minimum deformation under working conditions, and the installation interface position of the adjustment mechanism is reserved. Finally, the back panel blanking drawing is generated by surface unfolding.

[0024] 2.3) Edge banding material cutting design: First, the part of the stretch boundary surface that deviates more than 2mm from the forming reference surface in the direction of the working panel is cut off as the edge banding surface; second, the edge banding surface is unfolded to generate the edge banding unfolded drawing; finally, the edge banding unfolded drawing is divided according to the material length and edge structure to form the edge banding cutting drawing.

[0025] Furthermore, step four includes: firstly, on a forming platform of grade 0 or above, roughly assembling each rib according to the designed position using bolts and corner fittings; secondly, using a laser tracker or articulated arm to measure the upper surface of the roughly assembled frame ribs and comparing it with the theoretical frame surface, and repeatedly adjusting the frame mold accuracy by adjusting the corner fitting bolts, removing and polishing local burrs, and padding the bottom of the ribs with thin shims, until the RMS accuracy of the frame surface is less than 0.040mm; after the accuracy is adjusted to the correct position, checking and tightening the corner fitting connecting bolts one by one, requiring each bolt to be properly sealed with thread sealant to prevent loosening.

[0026] Further, step five includes: first, roughening the adhesive surfaces of the work panel and back panel, cleaning them with industrial alcohol of 95% or higher, and drying them with hot air; second, fully applying adhesive to the contact areas between the work panel, back panel, and the rib surfaces of the frame mold; then, laying and positioning the back panel, frame mold, work panel, and pad layer by layer on the marble forming platform; next, selecting an appropriate negative pressure based on the stress analysis of the surface film application, and performing negative pressure forming using a vacuum hood, with a negative pressure film application time of 2-4 hours; finally, allowing the panel to cure naturally at room temperature, with the curing time meeting the requirement of being greater than 70% of the adhesive's curing time.

[0027] Furthermore, step six includes: firstly, using a metal repair agent to adhesively seal the edge banding strip to the working panel and back panel; secondly, using a metal conductive repair agent to fill the stress gaps and then polishing with sandpaper of 800 grit or higher or a wool wheel; then, spraying the entire reflective surface to ensure that the primer and topcoat are sprayed evenly and the thickness is less than 0.02 mm, wherein the working surface uses a wave-transmitting paint with a wave transmittance of >97%; finally, re-testing the accuracy of the sprayed reflective surface, and the typical value of the final surface RMS accuracy is less than 0.045 mm.

[0028] Furthermore, it is formed by connecting two types of orthogonal horizontal and vertical ribs with corner fittings using threads.

[0029] Furthermore, the centerline projection of the ribs is used as the cutting diagram for the ribs to ensure the accuracy of the frame mold.

[0030] Furthermore, using a laser tracker to measure and adjust in real time can correct material cutting errors and improve the precision of the frame mold.

[0031] Furthermore, the working panel thickness is 0.5mm to 1.5mm, the rib thickness is more than 3mm, and the back panel and edge banding thickness is 1.0mm to 1.5mm.

[0032] This invention combines the advantages of solid molds and flexible molds, proposing an orthogonal assembly frame mold composite panel forming process. The final panel is formed by gluing the working surface, back plate, edge banding strip, and frame mold together. Its surface accuracy depends on the accuracy of the frame mold surface. During and after forming, there is virtually no residual stress or springback in the panel. Based on current technology, the peak-to-peak error of a single panel is less than 0.2 mm, and the RMS accuracy is better than 0.045 mm. The advantages of this process are:

[0033] 1) Because of the frame mold substrate, thinner materials can be used as the working surface, making it easier to meet the forming requirements of complex curved surfaces (such as large curvature, non-analytical curved surfaces, etc.);

[0034] 2) As long as the film on the working surface is properly applied during the negative pressure forming process and does not come unglued during use, the surface accuracy and long-term stability of the accuracy can be guaranteed. Therefore, the panel has better environmental adaptability and a wider range of applications.

[0035] 3) The reflector surface features a simple structure, high specific stiffness, large single-piece forming area, low forming stress and no springback, high forming accuracy, short curing time and high forming efficiency. It is particularly suitable for small-batch customization of complex-shaped antenna reflectors with ultra-large dimensions of 10m2 or more. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart illustrating the high-precision assembly frame skin negative pressure composite panel forming process in an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of a high-precision assembled frame mold skin negative pressure composite panel structure according to the present invention;

[0039] Figure 3 This is a schematic diagram of the theoretical curved surface of the panel to be formed in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the forming reference surface in an embodiment of the present invention;

[0041] Figure 5 This is a schematic sketch of the panel envelope and three-dimensional orthogonal centerline in an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram showing the details of the frame mold, front panel, and back panel in an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of negative pressure forming in an embodiment of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Contents not described in detail in the embodiments of this invention belong to prior art known to those skilled in the art.

[0045] like Figure 2 As shown, this invention provides a high-precision assembled frame skin negative pressure composite panel, which is formed by a working panel 1, a frame mold 2, a back plate 3, an edge sealing strip 4, and a room temperature curing structural adhesive 5 through negative pressure film bonding. The frame mold 2 includes transverse ribs, longitudinal ribs, connecting corner pieces, and connecting bolts. Figure 3 As shown, in this embodiment of the invention, the central region of the working surface is a paraboloid of revolution with a focal length of 5400mm, and the edge region is a non-analytic surface. In the design coordinate system, the projected size on the XOY plane is 4500mm × 2100mm, and the surface area of ​​the working surface is 11.23m². 2 It is characterized by its large area, complex shape, and high forming difficulty. For clarity, this embodiment uses CATIA software for visual modeling, such as... Figure 1 As shown, the specific implementation process includes the following steps:

[0046] Step 1: Design of a 3D orthogonal frame mold:

[0047] 1.1) A plane perpendicular to the normal at the geometric center point of the working surface of the panel to be formed, and at a distance of 60mm from the geometric center point of the selected frame model, is designated as the forming reference plane (hereinafter referred to as the reference plane). For example... Figure 4 As shown.

[0048] 1.2) Calculate the equidistant surfaces of the working curved surface of the panel to be formed based on the panel thickness of 1.0mm, thus obtaining the frame mold surface; take the boundary of the frame mold surface and stretch it along the normal of the reference surface to the forming reference surface to obtain the boundary stretching surface; take the intersection of the boundary stretching surface and the reference surface to obtain the reference section; combine the frame mold surface, the boundary stretching surface, and the reference section to obtain the closed three-dimensional envelope boundary of the panel, such as... Figure 5 As shown.

[0049] 1.3) Select the horizontal and vertical frame mold spacing as 150mm×150mm and the frame mold rib thickness as 4mm. Draw the center line sketches of the horizontal and vertical ribs on the forming reference plane respectively. The projection area of ​​the center line sketch is 200mm larger than the projection of the panel's three-dimensional envelope surface on the reference plane.

[0050] 1.4) The centerline sketch is stretched along the normal of the forming reference plane to form a rib array. The three-dimensional envelope boundary is used as the dividing boundary. The internal part of the rib array is divided to obtain the three-dimensional digital model of the frame mold.

[0051] 1.5) Complete the design of the joints of longitudinal and transverse stiffeners, corner fitting mounting holes, adjustment structure installation interfaces, and work panel positioning pins, etc., and generate stiffener cutting drawings by projecting the mid-section of each stiffener, such as... Figure 6 As shown.

[0052] Step Two: Design of Each Skin Segment and Cutting:

[0053] 2.1) Work Panel Segmentation and Cutting Design: First, based on the principle of ensuring the accuracy of the central area, the work panel is segmented according to the material and processing capacity, and the segmentation positions are determined. The total width of the segment gaps is determined according to a gap thickness ratio of 0.3, and all segment gaps are open. Second, the location and length of stress gaps are determined through finite element simulation. The width of stress gaps is determined according to a gap thickness ratio of 0.2. The segmented individual panels are not completely separated, and a connection area of ​​not less than 2mm is retained within every 400mm length of the stress gap. Next, the position of the work panel marker point is determined according to the optimization of minimizing deformation under working conditions, and a φ0.1mm circular hole is reserved. Then, based on the position of the work panel positioning hole pin on the rib, the positioning square hole on the work panel is determined, and its diameter is 0.1mm to 0.2mm larger on one side than the positioning hole pin on the rib. Next, the unfolded surface of the work panel is generated through surface unfolding. Then, the position of the φ1.0mm marker hole is determined on the unfolded surface, with the center of the unfolded shape of the reserved φ0.1mm circular hole as the center. See [reference missing]. Figure 6 .

[0054] 2.2) Backplate segmentation and cutting design: First, after the reference section edge is reduced by 10mm, the backplate is segmented according to the material size while ensuring rigidity. It is required that the backplate dividing line and the panel dividing line should avoid overlapping and should be orthogonal and staggered as much as possible. The cutting method is the same as in step 2.1. Second, the projection position of the working panel mark point on the backplate is determined according to the minimum deformation under working conditions, and the installation interface position of the adjustment mechanism is reserved. Finally, the backplate cutting drawing is generated by surface unfolding.

[0055] 2.3) Edge banding material cutting design: First, the part of the stretch boundary surface that is more than 2mm away from the standard surface is cut out as the edge banding surface; second, the edge banding surface is unfolded to generate the edge banding unfolded drawing; finally, the edge banding unfolded drawing is divided according to the material length and edge structure to form the edge banding cutting drawing.

[0056] Step 3: Cutting and blanking: First, use a laser cutting machine to cut the outer frame, positioning holes, mounting holes and stress gaps in that order. The cutting shape and position accuracy error should be ≤0.1mm.

[0057] Step 4: Frame Mold Assembly and Precision Adjustment: First, on a forming platform of grade 0 or above, roughly assemble each rib according to the designed position using bolts and corner fittings; second, use a laser tracker (or measuring equipment such as an articulated arm) to measure the upper surface of the roughly assembled frame ribs and compare it with the theoretical frame surface. Based on the error distribution, the frame mold precision can be repeatedly adjusted by adjusting corner fitting bolts, removing and polishing local burrs, and placing thin shims at the bottom of the ribs, until the RMS precision of the frame surface is less than 0.040mm; after the precision adjustment is in place, check and tighten each corner fitting connecting bolt, requiring each bolt to be properly sealed with thread sealant to prevent loosening.

[0058] Step 5: Panel Negative Pressure Film Application and Natural Curing: First, roughen the adhesive surfaces of the working panel 1 and back panel 3, then clean them with 95% or higher industrial alcohol and dry them with hot air; second, fully apply adhesive 5 to the contact areas between the working panel 1, back panel 3, and the rib surfaces of the frame mold 2; next, lay and position the back panel 3, frame mold 2, working panel 1, and pad 6 layer by layer on the marble forming platform 8; then, select an appropriate negative pressure based on the surface film application stress analysis, and use a vacuum hood 7 for negative pressure forming, setting the vacuum system 9 for 2-4 hours of negative pressure film application; finally, allow the panel to cure naturally at room temperature, ensuring the curing time is greater than 70% of the adhesive's curing time. Figure 7 As shown.

[0059] Step Six: Edge Sealing and Panel Surface Treatment: First, use a metal repair agent to adhesively seal the edge sealing strip to the working panel and back panel; second, fill the stress gaps with a metal conductive repair agent and then polish with 800-grit or higher sandpaper or a wool wheel; then, spray the entire reflective surface, ensuring that both the primer and topcoat are applied evenly and with a thickness of less than 0.02mm. For the working surface, a wave-transmitting paint with a transmittance of >97% is recommended; finally, re-measure the accuracy of the sprayed reflective surface. The typical RMS accuracy value of the final surface is generally required to be less than 0.045mm.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-precision assembly frame skin negative pressure composite panel forming process, applicable to large-size complex curved surfaces including non-analytical curved surfaces, 10 -2 The panel is formed with millimeter-level precision. The high-precision assembled frame skin negative pressure composite panel includes a frame mold, a working panel, a back panel, and edge sealing strips. It is bonded and formed on a high-precision vacuum negative pressure reference platform using room temperature curing adhesive. Its characteristic is... The high-precision assembly frame skin negative pressure composite panel forming process includes the following steps: Step 1: Design a 3D orthogonal frame mold, including: 1.1) A plane perpendicular to the geometric center point of the working surface of the panel to be formed, and whose distance from the geometric center point of the working surface of the panel to be formed is the thickness of the selected frame model, is made as the forming reference plane in the direction close to the back plate. 1.2) Calculate the equidistant surfaces of the working curved surface of the panel to be formed based on the thickness of the working panel to obtain the frame mold surface; 1.3) Take the boundary of the frame mold surface and stretch it along the normal of the forming reference surface to obtain the boundary stretching surface; take the intersection of the boundary stretching surface and the forming reference surface to obtain the reference section; combine the frame mold surface, the boundary stretching surface and the reference section to obtain the closed panel three-dimensional envelope boundary. 1.4) Based on the selected frame mold spacing and frame mold rib thickness, draw sketches of the center line positions of the transverse and longitudinal frame ribs on the forming reference plane, respectively, to ensure that the projection area of ​​the center line position sketch is larger than the projection range of the panel's three-dimensional envelope boundary on the reference plane, wherein the frame mold rib thickness is more than 3 mm. 1.5) The centerline position sketch is stretched along the normal of the forming reference plane to form a rib array. The three-dimensional envelope boundary of the panel is used as the dividing boundary. The internal part of the rib array is divided to obtain the overall digital model of the frame mold. 1.6) Complete the design of the stop at the splice of longitudinal and transverse ribs, the installation hole position of the corner piece, the installation interface of the adjustment structure, and the positioning hole pin of the work panel; 1.7) Generate the cutting diagram of the reinforcing bars by projecting the mid-section of each reinforcing bar; Step 2: Design the panel segmentation and cutting of each panel; Step 3: Cutting the material: First, use a laser cutting machine to cut the outer frame, positioning holes, mounting holes, and stress gaps in that order. The shape and position accuracy of the cut should be ≤0.1 mm. Step 4: Assemble the frame mold and adjust its precision; Step 5: Apply negative pressure to the panel and allow it to cure naturally; Step Six: Perform edge banding and panel surface treatment.

2. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 1, characterized in that, Step two includes: 2.1) In the design of the work panel segmentation and blanking, firstly, based on the principle of ensuring the accuracy of the central area, the work panel is segmented according to the material and processing capacity, and the segmentation position is determined. The total width of the segment gap is determined according to the gap thickness ratio of 0.3, and all segment gaps are open. Secondly, the position and length of the stress gap are determined through finite element simulation. The width of the stress gap is determined according to the gap thickness ratio of 0.

2. The single panel after segmentation is not broken as a whole, and at least a connection area of ​​not less than 2 mm is retained within every 400 mm length of the stress gap. Next, the position of the work panel marker point is determined according to the optimization of minimizing deformation under working conditions, and a circular hole with a diameter of 0.1 mm is reserved. Then, the positioning square hole on the work panel is determined according to the position of the positioning hole pin on the rib, and its diameter is 0.1 mm to 0.2 mm larger on one side than the positioning hole pin on the rib. Next, the unfolded surface of the work panel is generated by surface unfolding. Then, the position of the marker hole with a diameter of 1.0 mm is determined on the unfolded surface of the work panel with the center of the unfolded shape of the reserved 0.1 mm diameter circular hole as the center. Finally, the blanking drawing of the work panel is generated by surface unfolding. 2.2) In the design of back panel segmentation and blanking, firstly, after the edge of the reference section is reduced inward by 10 mm, the back panel is segmented according to the material size while ensuring rigidity. It is required that the back panel segmentation line and the panel segmentation line should not coincide, but should be orthogonal and staggered. The method of opening the gap is the same as in step 2.1). Secondly, the projection position of the working panel mark point on the back panel is determined according to the optimization of the minimum deformation under working conditions, and the installation interface position of the adjustment mechanism is reserved. Finally, the back panel blanking drawing is generated by surface unfolding. 2.3) Edge banding material cutting design: First, the part of the stretch boundary surface offset from the forming reference surface by more than 2mm in the direction of the working panel is cut off as the edge banding surface; second, the edge banding surface is unfolded to generate the edge banding unfolded drawing; finally, the edge banding unfolded drawing is divided according to the material length and edge structure to form the edge banding cutting drawing.

3. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 2, characterized in that, Step four includes: First, on a forming platform of grade 0 or above, the frame mold ribs are roughly assembled according to the designed positions using bolts and corner pieces; second, a laser tracker or articulated arm is used to measure the upper surface of the roughly assembled frame mold ribs and compare it with the theoretical frame surface. Based on the error distribution, the frame mold accuracy is repeatedly adjusted by adjusting corner pieces and bolts, removing and polishing local burrs, and placing thin shims at the bottom of the ribs until the RMS accuracy of the frame surface is less than 0.040mm; after the accuracy is adjusted to the correct position, each corner piece is checked to ensure it is locked and the bolts are connected. Each bolt is coated with thread sealant to prevent loosening.

4. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 3, characterized in that, Step five includes: first, roughening the adhesive surfaces of the work panel and back panel, cleaning them with industrial alcohol of 95% or higher, and drying them with hot air; second, fully applying adhesive to the contact areas between the work panel, back panel, and the frame mold ribs; then, laying and positioning the back panel, frame mold, work panel, and pad layer by layer on the marble forming platform; next, selecting an appropriate negative pressure based on the stress analysis of the surface film application, and using a vacuum hood for negative pressure forming, with a negative pressure film application time of 2-4 hours; finally, allowing the panel to cure naturally at room temperature, with the curing time meeting the requirement of being greater than 70% of the adhesive's curing time.

5. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 4, characterized in that, Step six includes: first, using a metal repair agent to adhesively seal the edge banding strip to the working panel and back panel; second, using a metal conductive repair agent to fill the stress gaps and then polishing with sandpaper of 800 grit or higher or a wool wheel; then, spraying the entire reflective surface to ensure that the primer and topcoat are evenly applied and that the thickness is less than 0.02 mm, with the working panel using a wave-transmitting paint with a transmittance >97%; finally, re-measuring the accuracy of the sprayed reflective surface, with the final surface RMS accuracy typically less than 0.045 mm.

6. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 1, characterized in that, The two types of orthogonal horizontal and vertical ribs are connected by threads through corner fittings.

7. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 1, characterized in that, The centerline projection of the ribs is used as the cutting diagram for the ribs to ensure the accuracy of the frame mold.

8. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 1, characterized in that, A laser tracker is used to measure and adjust in real time to correct material cutting errors and improve the precision of the frame mold.

9. The high-precision assembly frame skin negative pressure composite panel forming process according to claim 1, characterized in that, The working panel thickness is 0.5mm~1.5mm, the rib thickness is more than 3mm, and the back panel and edge banding thickness is 1.0mm~1.5mm.

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