Fixed-wing aircraft covering cloth manufacturing method based on CATIA software platform

Abstract

The invention belongs to the technical field of digital design, and particularly relates to a fixed wing aircraft covering cloth manufacturing method based on a CATIA software platform, three-dimensional curved surface modeling of an aircraft covering cloth is completed through the software platform, and the steps of designing, segmenting, unfolding, measuring, template exporting, tailoring, splicing, punching holes and the like of covering cloth cutting pieces are further completed. The method has the beneficial effects that by combining the digital design of a CATIA V5 software platform, the cutting and lofting of the fixed-wing aircraft covering cloth cutting piece are completed, the size adjustment and repeated trial and error of the covering cloth cutting piece are avoided, the design and development period is shortened, and the reference of the digital process is provided for the manufacturing of the aircraft covering cloth; most work design steps are completed at a computer end, and the material cost consumed in the whole covering cloth development process is remarkably reduced; the cover cloth design process and the airplane design process can be synchronously carried out, the development of support equipment is carried out at the early design stage of an airplane, and the rationality of the size and style of the cover cloth is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital design technology, and particularly relates to a method for manufacturing a fixed-wing aircraft cover based on the CATIA software platform. Background Art

[0002] With the development of China's low-altitude economy and the increase in the types of light fixed-wing aircraft, the demand for ground support equipment is increasing day by day. An aircraft cover is a ground support equipment that can provide protection for the aircraft body. During the daily operation of the aircraft, it is necessary to use the aircraft cover for necessary protection during ground parking to reduce the damage caused by sunlight, rain, snow and sand to the aircraft body and equipment.

[0003] The key to the external shape design of the aircraft cover is rain and wind protection. Other performances such as fire prevention and sun protection are mainly reflected in the material selection. When designing the aircraft cover, the following several elements usually need to be considered in addition to the material: First, in order to reduce the risk of aircraft water leakage, the principle of reducing sewing threads should be adhered to during the cover design process. The waterproof performance of the fabric itself must be better than the position where the fabric is sewn. Therefore, reducing the sewing part is an effective means to reduce water leakage. Second, in order to reduce the influence of crosswind, the external shape of the cover should fit the external shape surface of the aircraft as much as possible and be able to cover the main parts of the aircraft body, including the aircraft skin, the gaps between the skins and the exposed equipment, etc., which can effectively avoid the appearance of water accumulation points and reduce the risk of water seepage; Third, wind protection generally adopts the form of straps. Reinforcement points generally need to be designed at the connection parts between the straps and the cover to avoid the straps tearing the cover due to strong winds. Fourth, for the exposed equipment of the aircraft or other easily worn parts, such as the antenna windshield, the radome, etc., a raised wrapping cover should be designed to avoid damage to this part during the installation, use and disassembly processes; Fifth, the convenience of installation should be considered. The aircraft cover should ensure integrity as much as possible. Generally speaking, however, the size of the aircraft external shape is large and the shape is complex. For a fixed-wing aircraft, its external shape is generally divided into several parts such as the fuselage, wings, tail wings, and engine nacelles. If the whole cover cannot be used for covering, segmented design is required, and then each part is connected. The segmented parts generally adopt the methods of snap band bonding, zipper connection, sleeve buckle connection, and rope tying. At the same time, the connection parts must be accessible and easy for the operator to contact.

[0004] Generally speaking, the design of the aircraft covering is carried out after the production of the aircraft entity. Based on the aircraft drawings or its shape, actual measurements are taken, and then appropriate cutting patterns are planned. However, due to the presence of non-developable surfaces on the aircraft's curved surfaces, especially at the connection positions of the wings, tail fins, and fuselage, and the fabric is a two-dimensional surface before cutting. It is necessary to divide the non-developable surface of the covering into several developable surfaces through cutting and minimize the area distortion during the surface development. The lower the area distortion, the closer the area of the developed two-dimensional plane is to that of the three-dimensional surface, and the lower the degree of surface distortion. Therefore, the design of the cutting pattern of the cutting piece is particularly important. If the number of cuts or cutting pieces is too large, the length of the connection of the cutting pieces will increase, resulting in a higher complexity of the process; if the number is too small, the curvature of the cutting piece will deviate significantly from the curvature of the aircraft skin, increasing the gap between the covering and the aircraft or causing wrinkles.

[0005] The production of the aircraft covering generally mainly adopts the plane cutting method. This method needs to continuously improve the shape structure and cutting piece size of the aircraft covering through repeated trial and error in the practical process, and finally coordinate with the aircraft shape. The traditional covering design process generally includes the following steps: 1) Field measurement of the skin size of the aircraft; 2) Confirmation of the cutting piece size and drawing of the plane template; 3) Production of the plane template; 4) Cutting the fabric according to the plane template; 5) Assembly and sewing of the cutting pieces; 6) Trial fitting on the aircraft entity; 7) Adjustment of the cutting piece profile; 8) Determination of the final covering shape. The design of the cutting pieces of the aircraft covering and the adjustment of the contour details take a long time. Steps 1-5 need to be continuously repeated throughout the testing stage until a satisfactory forming effect of the aircraft covering is obtained, resulting in high time costs and material costs. At the same time, it cannot guarantee the fitting effect between the aircraft covering and the aircraft shape surface. Therefore, it is very necessary to improve the design method of the fixed-wing aircraft covering through digital design means. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for manufacturing the fixed-wing aircraft covering based on the CATIA software platform, overcoming the deficiencies of the prior art. Through the digital design combined with the CATIA V5 software platform, the design and division lofting of the cutting pieces of the fixed-wing aircraft covering are completed, thus avoiding the repeated trial and error process during the adjustment and production of the cutting piece size of the covering, saving the design cycle, and providing a reference for the digital process of manufacturing the aircraft covering.

[0007] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0008] A method for manufacturing the fixed-wing aircraft covering based on the CATIA software platform, which completes the three-dimensional surface modeling of the aircraft covering through the software platform, and further completes each step of the design, division, unfolding, measurement, template export, cutting, assembly, and punching of the covering cutting pieces. The specific steps are as follows:

[0009] 1) Modeling: Import the 3D digital model of the aircraft into the CATIA V5 software;

[0010] 2) Design: Complete the 3D surface design of the canvas in the Generative Shape Design module;

[0011] 3) Division: Use splines to divide the 3D canvas surface into several developable surfaces;

[0012] 4) Development: Unroll all the cut-piece 3D surfaces after division into 2D planes;

[0013] 5) Measurement: Project the 2D contours of each cut-piece in the Engineering Drawing module and determine the dimensions of the cut-piece template;

[0014] 6) Export the template: Export the vector drawing and make the cut-piece template;

[0015] 7) Cutting: Complete the fabric cutting according to the cut-piece template;

[0016] 8) Sewing: Sew and piece together the cut-pieces;

[0017] 9) Punching holes: Punch holes and install eyelets to complete the entire production process of the aircraft canvas.

[0018] The CATIA V5 software is a 3D design, analysis, and simulation software developed by Dassault Systèmes of France.

[0019] The design steps in step 2) are as follows: 1) Using the aircraft 3D digital model as a reference, use the "Extract" command in the Generative Shape Design module to extract the outer surface of the aircraft, use the "Fill" command to fill the positions where the surface is not extracted, and use the "Stitch" command to stitch the extracted surface and the filled surface into a complete surface; 2) Offset the complete surface outward by 0.03% d according to the general tolerance standard, where d is the maximum width of the aircraft fuselage in millimeters, measure the positions and protruding volumes of the exposed equipment on the aircraft, and design the protruding surface of the canvas at this position according to the three-dimensional dimensions of this volume to ensure that the protruding surface can accommodate the equipment and the minimum gap with the equipment is the same as the offset; 3) Stitch the protruding surface and the stitched surface, and use a measuring tool to check that the gap between the surface and the outer surface of the aircraft is not less than 3 mm.

[0020] The division steps in step 3) are as follows: 1) Use the "Spline" command in the Generative Shape Design to draw splines on the surface of the non-developable surface, and then use the "Split" command to divide all non-developable surfaces; 2) The canvas opening is designed on the lower surfaces of the fuselage, wings, and tail, and the width of the opening is not less than 150 mm. After confirming that the divided surface can be developed through the CATIA "Surface Development" command, the division result of the 3D canvas surface is obtained.

[0021] In step 4), all the divided surfaces in step 3) are unfolded into a plane, and the width of the plane edge is extended using the extrapolation extension command, with the extended width being 20 - 30 mm.

[0022] The measurement steps in step 5) are as follows: 1) Use the engineering drawing module to project the plane into a 2D wireframe, measure whether the lengths of the two side lines that need to be aligned for sewing are the same, and after confirming that they can be aligned, label each pair of aligned sewing side lines for easy identification during the sewing process; 2) Align the longest diagonal of the 2D wireframe with the long side of the cutting template according to the standard width of the cutting template material, and divide the 2D wireframe with the minimum number of cutting templates arranged in the normal directions of the long side and the short side of the cutting template to obtain the 2D contours of several cutting templates.

[0023] The process of exporting the cutting template in step 6) is as follows: First, export the file of the cutting template contour as a dxf vector drawing, import it into a laser engraving machine to make the cutting die. After the cutting die is made, it is necessary to splice the cutting die to confirm that the cutting size is within the error range, and finally number the cutting templates for subsequent splicing.

[0024] In step 7), after splicing the cutting dies obtained in step 6), place them on the fabric, draw side lines along the edges of the cutting dies, and cut the fabric.

[0025] The material of the cutting die in step 6) can be any one of cardboard, thin wood board, and acrylic board.

[0026] Repeat steps 2) to 8) to complete the cutting design and cutting of the left and right fuselages, left and right wings, and the exposed equipment on the aircraft, and finally complete the sewing of the covering cloth.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1) By combining the digital design of the CATIA V5 software platform, the division and lofting of the covering cloth cutting pieces of the fixed-wing aircraft are completed, avoiding the repeated trial-and-error process during the size adjustment and production of the covering cloth cutting pieces, shortening the design and development cycle, and providing a reference for the digital process of making the aircraft covering cloth;

[0029] 2) Through the design functions of the CATIA V5 software platform, most of the design steps are completed on the computer side, and the material cost consumed in the entire process of developing the covering cloth is significantly reduced;

[0030] 3) The design of the covering cloth can be carried out synchronously with the aircraft design process, and the development of the guarantee equipment can be carried out at an earlier stage of the aircraft design to ensure the rationality of the covering cloth size and style;

[0031] 4) The manufacturing method implemented through the CATIA V5 software platform can detect in advance the non-unfolding surfaces of the aircraft cover and details of external devices such as antennas, avoid surface defects in the later stage, reduce the process difficulty to a certain extent, and enable the surface shape of the cover to fit the external shape surface of the aircraft to the greatest extent.

[0032] 5) CATIA V5 is the most widely used CAD engineering software in the aviation field. This innovative design method of aircraft cover manufacturing technology based on the CATIA V5 software platform provides ideas for online and offline hybrid design methods and practices, and its practical achievements can also be applied to other application fields of aviation design. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the flowchart of the aircraft cover design in the embodiment of the present invention;

[0034] Figure 2 is the schematic diagram of the segmentation of the 2D wireframe by the cover cutting template in the embodiment of the present invention, showing the patterns of the left and right fuselage cover cuttings. The two cover cuttings are sewn together along the longitudinal seam to form the fuselage cover;

[0035] Figure 3 is the schematic diagram of the segmentation of the 2D wireframe by the cover cutting template in the embodiment of the present invention, showing the patterns of the left and right wing cover cuttings;

[0036] Figure 4 is the schematic diagram of the 2D cutting of the external devices on the aircraft in the embodiment of the present invention;

[0037] Figure 5 is the schematic diagram of the unfolded structure of the cover obtained after sewing the seams of each 2D cutting in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments required for use in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those of ordinary skill in the art, other specific embodiments can be obtained based on these specific embodiments without creative efforts.

[0040] The components of the embodiments of the present invention that are typically described and shown in detail in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0041] See Figures 1-5 , which is a method for manufacturing the fixed-wing aircraft canvas based on the CATIA software platform. The three-dimensional surface modeling of the aircraft canvas is completed through the software platform, and further steps such as the design, segmentation, unfolding, measurement, template export, cutting, splicing, and punching of the canvas cut pieces are completed. The specific steps are as follows:

[0042] Step 1) Modeling: Import the standard 3D digital model of the aircraft into the CATIA V5 software. The CATIA V5 software is developed by Dassault in France and is mainly used for three-dimensional design, analysis, and simulation in industries such as aerospace, automotive, shipbuilding, electronics, and consumer goods.

[0043] Step 2) Design: Complete the 3D surface design of the canvas in the Generative Shape Design module. Based on the 3D digital model of the aircraft, first use the "Extract" command in the Generative Shape Design module to extract the outer surface of the aircraft. Here, pay attention to avoiding extracting the surfaces with large curvatures such as the depressions and air inlets on the aircraft surface. Use the "Fill" command to fill the positions of the unextracted surfaces, and use the "Stitch" command to stitch the extracted surface and the filled surface into a complete surface. Second, offset the complete surface outward by 0.03% d (where d is the maximum width of the aircraft fuselage in millimeters) according to the general tolerance standard, aiming to accommodate the manufacturing errors of the aircraft skin and the canvas. Fourth, measure the positions and protruding volumes of the equipment protruding from the aircraft skin, and design the protruding surface of the canvas at this position according to the three-dimensional dimensions of the volume, ensuring that the protruding surface can accommodate the equipment and the minimum gap with the equipment is the same as the offset. Finally, stitch the protruding surface and the stitched surface, and use the measurement tool to check that the gap between the surface and the outer surface of the aircraft is not less than 3 mm.

[0044] Step 3) Segmentation: Use spline curves to segment the 3D surface of the canvas into several developable surfaces. The outer shape of a fixed-wing aircraft generally consists of several developable surfaces and non-developable surfaces (Gaussian curvature ≠ 0). Wings, fuselages, horizontal tails, etc. are generally partial developable surfaces, and connecting surfaces (such as wing-fuselage connecting surfaces) are generally non-developable surfaces.

[0045] First, use the "Spline" command in generative surface design to draw splines on the surface of the non-developable surface, and then use the "Split" command to split all non-developable surfaces; Second, since the canvas is unfolded from above the aircraft and fixed after covering the aircraft during use, it is necessary to design a canvas opening. The opening is designed to be divided by two parallel lines. In addition, for the convenience of disassembly and fixing of the canvas, the canvas opening should be designed on the lower surfaces of the fuselage, wings, and tail. Third, the width of the opening should be no less than 150 mm to leave enough tension space when fixing the canvas to make the canvas fit the aircraft surface better; Fourth, through the "Surface Development" command in CATIA, after confirming that the split surface can be developed, the split result of the canvas 3D surface is obtained.

[0046] Step 4) Unfolding: Unfold all the cut-piece 3D surfaces after splitting into 2D planes, unfold all the split surfaces into planes, and use the extrapolation extension command to extend the width of the plane edges. Note that the extended widths of the sewing edge and the opening edge of the canvas are different. The width of the sewing edge should leave enough sewing allowance according to different sewing methods (for example, for double-line sewing, it is necessary to extend a width of no less than 20 mm); since the opening edge needs to be punched or sealed, the extrapolation extension is no less than 30 mm in width.

[0047] Step 5) Measuring: Project the 2D contours of each cut-piece in the engineering drawing module and determine the size of the cut-piece template. First, use the engineering drawing module to project the plane into a 2D wireframe. Second, measure whether the lengths of the two side edges that need to be aligned for sewing are the same. After confirming that they can be aligned, mark each pair of aligned sewing side edges to facilitate identification during the sewing process; Third, align the longest diagonal of the 2D wireframe with the long side of the cut-piece template according to the standard width of the cut-piece template material (such as cardboard, thin wood board, acrylic board, etc.), and divide the 2D wireframe with the minimum number of cut-piece templates arranged in the normal directions of the long side and short side of the cut-piece template, as shown in the figure. Obtain the 2D contours of several cut-piece templates.

[0048] Step 6) Exporting the template: Export the vector drawing and make the cut-piece template. First, export the file of the cut-piece template contour as a dxf vector drawing and import it into the laser engraving machine to make the cut-piece die; Second, after the cut-piece die is made, it is necessary to splice the cut-piece die to confirm that the cutting size is within the error range; Finally, number the cut-piece templates for easy splicing.

[0049] Step 7) Cutting: Complete the fabric cutting according to the cut-piece template. After splicing the cut-piece die, place it on the fabric, draw the side lines on the fabric along the edge of the die, and perform fabric cutting.

[0050] Step 8) Splicing: Cut-piece splicing and sewing. Splice and sew the cut fabric pieces according to the marks on the cut-piece template.

[0051] Step 9): Punch holes and install grommets to complete the entire production process of the aircraft cover. After sewing the cover pieces, holes need to be punched and grommets riveted at the edges of the opening positions to provide fixed positions for the straps.

[0052] For the surface dimensions and positions of the exposed equipment on the aircraft obtained during the modeling process, corresponding template pieces for the cover are designed. Repeat Steps 2) to 8) to complete the design and cutting of the covers for the left and right fuselages, left and right wings, and the exposed equipment on the aircraft. Finally, complete the seam joining of the cover to obtain the final cover for the fixed-wing aircraft.

[0053] When the cover of the present invention is in use, after covering the top of the fixed-wing aircraft from head to tail, the left and right sides are wrapped downwards and joined together at the belly of the aircraft; the cover on the fixed wing is wrapped downwards from the front and back of the fixed wing and joined together below the fixed wing, and the joining seam below the fixed wing extends downwards to the joining position at the belly of the aircraft; the joining positions are all connected by elastic hook-and-loop fasteners, and the elastic hook-and-loop fasteners can apply a certain pulling force to the joining positions to ensure a good fit between the cover and the aircraft body, reducing the damage caused by sunlight, rain, snow, and sand and dust to the aircraft body and exposed equipment.

[0054] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for making fixed-wing aircraft fabric based on CATIA software platform, characterized in that: The software platform is used to complete the three-dimensional surface modeling of the aircraft fabric, and further complete the steps of designing, segmenting, unfolding, measuring, exporting templates, cutting, splicing and punching holes for the fabric pieces. The specific steps are as follows: 1) Modeling: import the aircraft 3D digital model into CATIAV5 software; 2) Design: Complete the 3D surface design of the fabric in the generative surface design module; 3) Segmentation: Use splines to segment the 3D surface of the fabric into several developable surfaces; 4) Expanding: Expand all the 3D surfaces of the split pieces into 2D planes; 5) Measure, project the 2D outline of each piece in the engineering drawing module, and determine the size of the piece template; 6) Export templates, export vector graphics and make cutting templates; 7) Cutting: Cut the fabric according to the cutting template; 8) Stitching, piece joining and sewing; 9) Punch holes, drill holes and install eyelet buckles to complete the entire production process of aircraft cover.

2. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: The CATIAV5 software is a three-dimensional design, analysis and simulation software developed by Dassault Systèmes of France.

3. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: The design steps in step 2) are as follows: 1) taking the 3D digital model of the aircraft as a reference, using the "extract" command in the generative surface design module to extract the outer surface of the aircraft, using the "fill" command to fill the position of the unextracted surface, and using the "join" command to join the extracted surface and the filled surface into a complete surface; 2) offsetting the complete surface outward by 0.03%d according to the general tolerance standard, where d is the maximum width of the aircraft fuselage in millimeters, measuring the position and protruding volume of the exposed equipment on the aircraft, and designing the convex surface of the cloth at this position according to the three-dimensional size of the volume, ensuring that the convex surface can accommodate the equipment and the minimum gap with the equipment is the same as the offset; 3) stitching the convex surface and the joint surface, and using a measuring tool to check that the gap between the surface and the outer surface of the aircraft is not less than 3mm.

4. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: The segmentation steps in step 3) are as follows: 1) Use the "Spline" command in the generative surface design to draw splines on the surface of the non-developable surface, and then use the "Split" command to segment all non-developable surfaces; 2) The fabric openings are designed on the lower surfaces of the fuselage, wings and tail, and the width of the openings is not less than 150 mm. After confirming that the segmented surface can be expanded through the CATIA "Surface Unfolding" command, the segmentation result of the fabric 3D surface is obtained.

5. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: In the step 4), all the divided surfaces in step 3) are unfolded into planes, and the width of the edge of the plane is extended by 20-30 mm using the "extrapolation extension" command.

6. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: The measurement steps in step 5) are as follows: 1) Use the engineering drawing module to project the plane into a 2D wireframe, measure whether the lengths of the two side lines that need to be aligned for sewing are the same, and after confirming that they can be aligned, mark each pair of side lines that are aligned for sewing to facilitate identification during the sewing process; 2) According to the standard width of the cutting template material, the longest diagonal line of the 2D wireframe is overlapped with the long side of the cutting template, and the 2D wireframe is divided by arranging the minimum number of cutting templates in the normal direction of the long side and the normal direction of the short side of the cutting template to obtain the 2D contours of several cutting templates.

7. The method for making fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: The process of exporting the cutting template in step 6) is: first export the file of the cutting template outline as a dxf vector diagram, import it into a laser engraving machine to make a cutting mold, and after the cutting mold is made, it is necessary to splice the cutting mold to confirm that the cutting size is within the error range, and finally number the cutting template for subsequent splicing.

8. The method for manufacturing fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: In the step 7), the cutting piece molds obtained in the step 6) are spliced ​​together and placed on the cloth, and a border line is drawn on the cloth along the edge of the cutting piece mold to cut the cloth.

9. The method for manufacturing fixed-wing aircraft fabric based on CATIA software platform according to claim 7, characterized in that: The material of the cutting mold in step 6) is any one of thick cardboard, thin wood board and acrylic board.

10. The method for manufacturing fixed-wing aircraft fabric based on CATIA software platform according to claim 1, characterized in that: Repeat steps 2) to 8) to complete the design and cutting of the left and right fuselages, left and right wings, and exposed equipment on the aircraft, and finally complete the stitching of the cover fabric.

Images