Apparatus and method for forming high dimensional accuracy long stringer skin integrated composite wall panels

Abstract

The application discloses a device and a method for forming a long-string skin-integrated composite wallboard with high size precision, the device comprising a skin forming die and a long-string flexible pressing die; the forming method comprising: laying up skin layers on a process surface; assembling L-shaped and C-shaped long-string blank materials into corresponding long-string accommodation slots to form a combination; sequentially assembling the combination to the process surface and positioning; clamping the combination through a long-string combination clamp, so that the flexible pressing pad is compressed to a theoretical combination position; installing a long-string end head pressing plate to press each combination; after removing the occupying sheet and the combination clamp, encapsulating into a hot pressing tank for curing; and detecting the long-string position precision after demolding. The rigid part and the flexible part are organically combined, the long-string axial position precision and the internal quality of the part are ensured, the formed part has high size precision, and the operation is convenient and the manufacturing efficiency is high.

Description

Technical Field

[0001] This invention belongs to the field of composite material parts manufacturing, specifically relating to an apparatus and method for molding high-precision long stringer skin integrated composite wall panels. Background Technology

[0002] Fiber-reinforced resin matrix composites, as an advanced material, are increasingly widely used in aircraft manufacturing due to their advantages such as high specific strength and specific modulus, good corrosion resistance, high designability, and good fatigue resistance. As composite material components account for an increasingly larger proportion of the overall aircraft, these components are also developing towards larger sizes, greater complexity, and more integrated structures.

[0003] Integrated stringer-skin panels are a new type of composite material panel that has emerged in recent years. Unlike traditional stringer-reinforced panels, the stringer and skin plies are integrated in this design. In traditional stringer-reinforced panels, the stringer and skin plies are separate components, and large stringer-reinforced panels often use co-bonding with two curing cycles to assemble the parts, followed by fasteners installed on the stringer edges to ensure overall strength. Integrated stringer-skin panels reduce the use of fasteners connecting the stringer and skin, eliminating the risk of debonding and significantly contributing to aircraft weight reduction and improved panel performance. However, integrated stringer-skin panels cannot be formed using traditional metal stringer core molds, posing a challenge to the molding and manufacturing technology of this new structural component.

[0004] Currently, the molding methods used for this type of integrated stringer skin panel include: integral flipping device molding and composite cover plate molding. Integral flipping device molding involves assembling the stringer layers, flipping them using a flipping device, laying 0-degree fibers in the radius corner area, compacting, and then flipping them back to their original position before combining them with the skin layers. This molding method is cumbersome, requires a large equipment footprint, has low manufacturing efficiency, and due to the high rigidity of the device, internal quality issues are prone to occur. Composite cover plate molding involves sequentially positioning each stringer layer on the skin using a composite cover plate. This method can better guarantee the internal quality of the parts, is lower in cost, and is convenient to operate. However, because the rigidity of the composite cover plate in this form is lower than that of a metal mandrel, it cannot guarantee high stringer positional accuracy. Parts manufactured using this method are suitable for aircraft parts where stringer positional accuracy is not critical. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for molding high-precision integrated composite wall panels with stringer skin. The apparatus is used to mold integrated composite wall panels with stringer skin. The molded parts have high dimensional accuracy, good internal quality, and are easy to operate with high manufacturing efficiency.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An apparatus for forming high-precision stringer skin integrated composite wall panels, including a skin forming mold and a stringer flexible pressure mold that cooperates with it. The main body of the skin forming mold is a process surface with the same aerodynamic shape as the wall panel. The outer side of the process surface is provided with long string end positioning strips and long string side positioning strips. After the long string flexible pressure mold is assembled on the process surface, the long string end pressure plate is used to realize the positioning and clamping of the long string flexible pressure mold. The stringer flexible pressure mold includes multiple L-shaped rigid limiting pressure plates; the stringer relief groove is machined on the vertical side and horizontal bottom of the L-shaped rigid limiting pressure plate to form a working surface for mating with the inner surface of the L-shaped stringer blank and the C-shaped stringer blank; a flexible pressure pad is set in the stringer relief groove, and the vertical plates of adjacent L-shaped rigid limiting pressure plates are fixed together by the stringer combination clamp.

[0007] Furthermore, the stringer end pressure plate is positioned and connected to the inner side of the stringer end positioning strip by a positioning pin, which is used to flatten and fix the stringer flexible pressure mold; the stringer end pressure plate is provided with multiple grooves at intervals to make way for the vertical edge of the L-shaped rigid limiting pressure plate; the part between the grooves presses against the horizontal edge end of the L-shaped rigid limiting pressure plate.

[0008] Furthermore, a gap is reserved between the end plate of the long stringer and the vertical edge of the L-shaped rigid limiting plate; a gap is reserved between the splice joints of a set of L-shaped rigid limiting plates corresponding to the C-shaped long stringer blank; and a gap is reserved between the vertical plates of adjacent L-shaped rigid limiting plates.

[0009] Furthermore, the flexible pressure pad is bonded to the surface of the stringer relief groove through an adhesive layer, and is used to apply flexible pressure to the L-shaped stringer blank and C-shaped stringer blank during curing; the coefficient of thermal expansion of the flexible pressure pad is greater than that of the L-shaped rigid limiting pressure plate.

[0010] Furthermore, an air guide groove is designed around the clearance groove along the upper edge of the L-shaped rigid limiting pressure plate, and a replaceable air guide rope is placed in the air guide groove to release the vacuum during curing.

[0011] Furthermore, for the two L-shaped stringer blanks on both sides of the integrated stringer skin panel, an L-shaped rigid limiting plate is used for assembly; the horizontal edge of this L-shaped rigid limiting plate is a straight edge, which directly mates with the positioning strip surface of the stringer side for positioning; while for the remaining multiple C-shaped stringer blanks, each C-shaped stringer blank needs to be assembled using a set of L-shaped rigid limiting plates. The set of L-shaped rigid limiting plates are arranged opposite each other and are assembled together into a U-shaped structure, which is connected and fixed by connecting blocks and screws.

[0012] Furthermore, the long stringer combination clamp includes a C-clamp and a tightening handle; the C-clamp is straddling the outside of the vertical edges of two adjacent L-shaped rigid limiting pressure plates, and the clamping opening of the C-clamp is narrowed by rotating the tightening handle, thus applying opposing pressure to the two L-shaped rigid limiting pressure plates.

[0013] Furthermore, an L-shaped spacer is provided between the vertical edges of the two L-shaped rigid limiting pressure plates when the long stringer combination clamp is tightened.

[0014] An L-shaped spacer is provided between the vertical edges of the two L-shaped rigid limiting pressure plates during fastening.

[0015] A method for molding high-dimensional precision stringer skin integrated composite wall panels includes: Step 1: Lay up the skin layers on the process surface of the skin forming mold; Step 2: Assemble the stringer end positioning strip and stringer side positioning strip onto the main body of the skin forming mold using positioning pins and tightening bolts, and surround the process surface; Step 3: Assemble the L-shaped stringer blanks on both sides of the pre-laid and pre-formed stringer skin integrated wall panel into the stringer clearance groove of the corresponding L-shaped rigid limiting pressure plate. Separate the L-shaped stringer blanks from the flexible pressure pads 3-4 with an isolation film, and fix the L-shaped stringer blanks 1-5 with contactable tape to obtain an L-shaped assembly. Step 4: Assemble the two assembled L-shaped assemblies onto both sides of the process surface. The length and width directions of the L-shaped rigid limiting pressure plate are respectively aligned and positioned with the end positioning strip of the stringer and the side positioning strip of the stringer. Step 5: Fill the R-corner area of ​​the L-shaped stringer blank of the L-shaped assembly from the side with the pre-formed 0-degree fiber and compact it to complete the assembly of the L-shaped rigid limiting pressure plates on both sides and the two L-shaped stringer blanks. Step 6: On the inner side of the L-shaped assembly on one side, assemble a set of L-shaped rigid limiting pressure plates corresponding to the first C-shaped stringer blank; the set of L-shaped rigid limiting pressure plates 3-1 are arranged opposite each other and assembled into a U-shaped structure; Step 7: Assemble the C-shaped stringer blank that has been laid out and preformed into the stringer clearance groove in the fixed U-shaped structure. Separate the C-shaped stringer blank from the flexible pressure pad with an isolation film and fix the C-shaped stringer blank with contactable tape to obtain the C-shaped assembly. Step 8: Assemble the C-type assembly onto the process surface near the L-type assembly. Align the C-type assembly with the end positioning strip of the stringer along its length and with the L-type rigid limiting plate of the C-type assembly in its width direction. Insert an L-type spacer in the middle to maintain a gap between the two. Install the stringer assembly clamp on the vertical edge of the adjacent L-type rigid limiting plate. Step 9: Fill the R-corner area of ​​the L-shaped stringer blank of the C-shaped assembly from the side with the pre-formed 0-degree fiber and compact it; complete the assembly of the first C-shaped assembly. Step 10: Following the same method as steps 6 to 9, assemble all other C-type assemblies in sequence; Step 11: Install the stringer end pressure plate on the stringer end positioning strip using positioning pins; Step 12: Remove the connecting block, L-shaped spacer piece, and long stringer assembly clamp; Step 13: Cover the surface of the device with an isolation film, a breathable felt, and a vacuum bag in sequence. The sealing materials are overlapped. Use sealing strips to bond the vacuum bag to the skin forming mold. Expel the air from the bag through the vacuum nozzle and put it into a thermostatic jar to complete the curing of the parts. Step 14: After curing, remove the end pressure plate, end positioning strip, and side positioning strip of the stringer. Remove each stringer flexible pressure mold from the edge to the middle.

[0016] Furthermore, the method also includes: Step 15: Reinstall the stringer end positioning strip and stringer end pressure plate, and check the stringer position accuracy; after the accuracy meets the requirements, remove the stringer end positioning strip and stringer end pressure plate, and demold the entire stringer skin integrated wall panel. After demolding, cut the skin and stringer allowance to the net size to obtain the processed stringer skin integrated wall panel.

[0017] Compared with the prior art, the present invention has the following technical features: The molding apparatus for high-precision integrated composite material wall panels with stringer skin provided by this invention organically combines rigid and flexible components. These components complement each other, fully leveraging their respective material properties and optimizing the overall effect by utilizing the characteristics of different materials. The rigid limiting pressure plate of the stringer precisely controls the axial position of the stringer, while the flexible pressure pad applies uniform pressure to the stringer blank during curing by utilizing the difference in thermal expansion coefficients, ensuring the internal quality of the part. This molding apparatus for high-precision integrated composite material wall panels with stringer skin provided by this invention solves the problem that while traditional "rigid-to-rigid" devices produce parts with high external precision, their internal quality is poor. It also overcomes the shortcomings of flexible devices, which, while having good internal pressure transmission, generally have lower external precision. Furthermore, it is easy to operate and has high manufacturing efficiency. This invention breaks through the technological barriers of traditional integrated stringer skin wall panel manufacturing, achieving the manufacturing of high-precision parts and ensuring part quality. It can be widely applied in the field of composite material part manufacturing technology. Attached Figure Description

[0018] Figure 1 A schematic diagram of an integrated wall panel for a long stringer skin; Figure 2This is a schematic diagram of the skin forming mold; Figure 3 Schematic diagram of the end plate of the stringer; Figure 4 A schematic diagram of a long stringer flexible pressurization mold (without flexible pressurization pads and air guide ropes installed); Figure 5 This is a schematic diagram showing the positions of the adhesive layer, flexible pressure pad, and air guide rope. Figure 6 This is a schematic diagram of two sets of flexible pressurized molds with long stringers. Figure 7 Enlarged view of the positions of the long stringer assembly fixture and the L-shaped spacer piece; Figure 8 A schematic diagram of two flexible pressurizing molds with long stringers combined within the same C-shaped groove; Figure 9 A schematic diagram of the completed flexible pressurization mold assembly for the long stringer.

[0019] Explanation of reference numerals in the attached drawings: 1-Integrated stringer skin panel, 1-1-Pneumatic profile, 1-2-Skin layup, 1-3-Stringer layup, 1-4-0 degree fiber, 1-5-Stringer blank; 2-Skin forming mold, 2-1-Process surface, 2-2-Stringer end positioning strip, 2-3-Stringer side positioning strip, 2-4-Stringer end pressure plate, 2-5-Positioning pin, 2-6-Tightening bolt; 3-Stringer flexible pressure mold, 3-1-L-shaped rigid limiting pressure plate, 3-2-Stringer clearance groove, 3-3-Adhesive layer, 3-4-Flexible pressure pad, 3-5-Air guide groove, 3-6-Air guide rope, 3-7-Connecting block, 3-8-Screw, 3-9-Stringer combination clamp, 3-9-1-C-type clamp, 3-9-2-Tightening handle, 3-10-L-shaped spacer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] See Figure 1 The diagram shows a schematic of an integrated stringer skin panel 1. The outermost layer of the panel is an aerodynamic profile 1-1, the inner side of the aerodynamic profile 1-1 is a skin layer 1-2, and a stringer layer 1-3 is set inside the skin layer 1-2. The stringer layer 1-3 includes multiple adjacent C-shaped stringer blanks 1-5, and L-shaped stringer blanks 1-5 are set on the outer side of the C-shapes at both ends. In the cross-section, the rounded transition area between the horizontal and vertical edges of the adjacent C-shaped stringer blanks 1-5 and L-shaped stringer blanks 1-5 is an R-corner area, which needs to be filled with 0-degree fibers 1-4.

[0022] Part 1: Forming apparatus for high-precision long stringer skin integrated wall panel.

[0023] The high-precision stringer skin integrated wall panel forming device provided by the present invention mainly includes two parts: skin forming mold 2 and stringer flexible pressure mold 3. The device organically combines rigid and flexible components. The rigid component ensures the positional accuracy of the stringer axis, and the flexible component provides uniform pressure during curing to ensure internal quality.

[0024] 1. Skin forming mold 2.

[0025] The main body of the skin forming mold 2 is made of INVAR steel, including the same process surface 2-1 as the aerodynamic shape surface 1-1 of the wall panel, the end positioning strip 2-2 of the stringer, the side positioning strip 2-3 of the stringer, the end pressure plate 2-4 of the stringer, the positioning pin 2-5, and the tightening bolt 2-6.

[0026] The main body of the skin forming mold 2 is a curved structure. A process surface 2-1, formed by the end positioning strip 2-2 and the side positioning strip 2-3 of the stringer, is provided on the inner surface of the main body of the skin forming mold 2. The end positioning strip 2-2 and the side positioning strip 2-3 of the stringer are positioned and connected to the main body of the skin forming mold 2 by positioning pins 2-5 and tightening bolts 2-6, respectively used for limiting the length and width of the stringer. The positioning pins 2-5 are used to achieve precise positioning between components, and the tightening bolts 2-6 are used to achieve a tight connection between components. The process surface 2-1 is used for the layering of the skin ply 1-2.

[0027] The stringer end pressure plate 2-4 is positioned and connected to the inner side of the stringer end positioning strip 2-2 via positioning pins 2-5. It is used to flatten and fix the stringer flexible pressure mold 3 to ensure the surface quality at the stringer end. Multiple grooves are spaced apart on the stringer end pressure plate 2-4 to accommodate the vertical edge of the L-shaped rigid limiting pressure plate 3-1. The portion between the grooves presses against the horizontal edge of the L-shaped rigid limiting pressure plate 3-1. A certain gap is reserved between the stringer end pressure plate 2-4 and the vertical edge of the L-shaped rigid limiting pressure plate 3-1 (i.e., the grooves do not contact the vertical edge), which serves a dual purpose: firstly, to assist in the positioning of the stringer flexible pressure mold 3; and secondly, to provide space for axis detection after curing and demolding. This gap provides space for the thermal expansion of the stringer flexible pressure mold 3 during curing, avoiding rigid interference; and provides operational space for axis detection after demolding.

[0028] 2. Long stringer flexible pressure mold 3.

[0029] The long stringer flexible pressure mold 3 is the core part of the molding device, including an L-shaped rigid limiting pressure plate 3-1, a long stringer clearance groove 3-2, an adhesive layer 3-3, a flexible pressure pad 3-4, an air guide groove 3-5, an air guide rope 3-6, a connecting block 3-7, a screw 3-8, a long stringer combination clamp 3-9, and an L-shaped occupant piece 3-10.

[0030] The L-shaped rigid limiting pressure plate 3-1 is made of INVAR steel. Long string relief grooves 3-2 are machined on the vertical side and the bottom of the horizontal side of the L-shaped rigid limiting pressure plate 3-1, which together form a working surface for mating with the inner surfaces of the L-shaped long string blank 1-5 and the C-shaped long string blank 1-5. That is, the L-shaped rigid limiting pressure plate 3-1 is composed of a vertical side and a horizontal side, and the working surface is the long string relief groove 3-2 machined on the outer surface of the vertical side and the horizontal side, so that the inner surfaces of the L-shaped long string blank 1-5 and the C-shaped long string blank 1-5 can be embedded therein. The long string relief groove 3-2 places and positions the L-shaped long string blank 1-5 and the C-shaped long string blank 1-5 during assembly, and the size matches it to ensure the positional stability of the blanks during the pressurization process.

[0031] The flexible pressure pad 3-4 is bonded to the surface of the stringer relief groove 3-2 via the adhesive layer 3-3. It is used to apply flexible pressure to the L-shaped stringer blank 1-5 and C-shaped stringer blank 1-5 during curing. The coefficient of thermal expansion of the flexible pressure pad 3-4 is greater than that of the L-shaped rigid limiting plate 3-1. During the curing heating process, the flexible pressure pad 3-4 expands due to heat. Because the L-shaped rigid limiting plate 3-1 provides rigid constraint to the outer side of the flexible pressure pad 3-4, the expansion displacement is applied directionally to the surfaces of the L-shaped stringer blank 1-5 and C-shaped stringer blank 1-5, achieving uniform pressure on the blanks. The sum of the thicknesses of the adhesive layer 3-3, the flexible pressure pad 3-4, and the single-sided stringer blank 1-5 is greater than the depth of the stringer relief groove 3-2 to ensure effective pressure application.

[0032] The L-shaped rigid limiting pressure plate 3-1 is surrounded by the long stringer relief groove 3-2. The air guide groove 3-5 is designed around it. The air guide groove 3-5 is filled with a replaceable air guide rope 3-6, which is used to release the vacuum during curing.

[0033] For the two L-shaped stringer blanks 1-5 on both sides of the integrated stringer skin panel 1, an L-shaped rigid limiting plate 3-1 is used for assembly (the inner surface of the L-shaped stringer blank 1-5 is embedded in the stringer clearance groove 3-2 of the L-shaped rigid limiting plate 3-1); the horizontal edge of this L-shaped rigid limiting plate 3-1 is a straight edge, which directly cooperates with the side positioning strip 2-3 of the stringer for positioning. For the remaining C-shaped stringer blanks 1-5, each C-shaped stringer blank 1-5 needs to be assembled using a set of L-shaped rigid limiting pressure plates 3-1 (the inner surface of the C-shaped stringer blank 1-5 is embedded with the concave stringer clearance groove 3-2); specifically, a set of L-shaped rigid limiting pressure plates 3-1 are arranged opposite each other and are assembled together into a concave structure. The splicing is a ramp fit, and a certain gap is reserved at the splicing seam. They are connected and fixed by connecting blocks 3-7 and screws 3-8, so that the relative position of the C-shaped stringer blanks 1-5 remains unchanged during the overall transfer and assembly process.

[0034] The stringer assembly clamp 3-9 includes a C-type clamp 3-9-1 and a tightening handle 3-9-2. The C-type clamp 3-9-1 is straddling the outside of the vertical edges of two adjacent L-shaped rigid limiting pressure plates 3-1. By rotating the tightening handle 3-9-2, the clamping opening of the C-type clamp 3-9-1 is narrowed, applying opposing pressure to the two L-shaped rigid limiting pressure plates 3-1. This clamp is used to apply pressure to the vertical edges of the stringer at a certain distance after the adjacent L-shaped rigid limiting pressure plates 3-1 are assembled. By compressing the flexible pressure pad 3-4, the theoretical assembly position is achieved, ensuring that the position of the stringer is accurately controlled by the L-shaped rigid limiting pressure plates 3-1 and the L-shaped occupant 3-10.

[0035] L-shaped spacer plates 3-10 are used to insert between adjacent L-shaped rigid limiting pressure plates 3-1 during the assembly of the upright plates, and are removed after all stringers are assembled. After all stringers are assembled, the L-shaped spacer plates 3-10 are removed. At this time, the stringer blanks 1-5 have been fixed by the expansion force of the flexible pressure pads 3-4. After the spacer plates are removed, the gap between the L-shaped rigid limiting pressure plates 3-1 provides space for the subsequent thermal expansion of the flexible pressure pads 3-4.

[0036] Part Two: Forming Method for High-Precision Long Truss Skin Integrated Wall Panels

[0037] Based on the above-described molding apparatus, the method of using the high-precision stringer skin integrated wall panel molding apparatus provided by the present invention includes the following steps: Step 1: Lay up the skin layers 1-2 on the process surface 2-1 of the skin forming mold 2.

[0038] Step 2: Using positioning pins 2-5 and tightening bolts 2-6, assemble the stringer end positioning strip 2-2 and stringer side positioning strip 2-3 onto the main body of the skin forming mold 2, surrounding the process surface 2-1.

[0039] Step 3: Assemble the L-shaped stringer blank 1-5 on one side of the pre-laid and pre-formed stringer skin integrated wall panel 1 into the stringer clearance groove 3-2 of the corresponding L-shaped rigid limiting pressure plate 3-1. Separate the L-shaped stringer blank 1-5 from the flexible pressure pad 3-4 with an isolation film, and fix the L-shaped stringer blank 1-5 with contactable tape to obtain an L-shaped assembly. Use the same method to complete the assembly of the L-shaped stringer blank 1-5 on the other side with the L-shaped rigid limiting pressure plate 3-1 to obtain another L-shaped assembly.

[0040] Step 4: Assemble the two assembled L-shaped assemblies onto both sides of the process surface 2-1. The length and width directions of the L-shaped rigid limiting pressure plate 3-1 are respectively aligned and positioned with the end positioning strip 2-2 and the side positioning strip 2-3 of the stringer.

[0041] Step 5: Fill the R-corner area of ​​the L-shaped stringer blank 1-5 of the L-shaped assembly with the pre-formed 0-degree fiber 1-4 from the side and compact it to complete the assembly of the L-shaped rigid limiting pressure plate 3-1 on both sides and the two L-shaped stringer blanks 1-5.

[0042] Step 6: On the inner side of the L-shaped assembly on one side, assemble a set of L-shaped rigid limiting pressure plates 3-1 corresponding to the first C-shaped stringer blank 1-5; the set of L-shaped rigid limiting pressure plates 3-1 are arranged opposite each other and assembled into a U-shaped structure; the set of L-shaped rigid limiting pressure plates 3-1 are connected and fixed by connecting blocks 3-7 and screws 3-8.

[0043] Step 7: Assemble the completed and pre-formed C-shaped stringer blanks 1-5 into the stringer clearance grooves 3-2 of a set of L-shaped rigid limiting pressure plates 3-1 in the fixed U-shaped structure, such as... Figure 8 As shown, the C-shaped stringer blank 1-5 is inserted into the assembled stringer clearance groove 3-2 from bottom to top. The C-shaped stringer blank 1-5 is separated from the flexible pressure pad 3-4 by the isolation film, and the C-shaped stringer blank 1-5 is fixed with contactable tape to obtain the C-shaped assembly.

[0044] Step 8: Assemble the C-type assembly onto the process surface 2-1 near the L-type assembly. The length of the C-type assembly aligns with the end positioning strip 2-2 of the stringer, and the width aligns the L-type rigid limiting plate 3-1 of the C-type assembly with the L-type rigid limiting plate 3-1 of the L-type assembly. Insert an L-type spacer 3-10 in the middle to maintain a gap between the two. Install the stringer assembly clamp 3-9 on the vertical edge of the adjacent L-type rigid limiting plate 3-1. By tightening the handle 3-9-2, use the C-type clamp 3-9-1 to clamp the C-type assembly and the L-type assembly. At this time, the flexible pressure pad 3-4 is compressed to the theoretical assembly position.

[0045] Step 9: Fill the R-corner area of ​​the L-shaped stringer blank 1-5 of the C-shaped assembly with the pre-formed 0-degree fibers 1-4 from the side and compact them; complete the assembly of the first C-shaped assembly.

[0046] Step 10: Following the same method as steps 6 to 9, assemble all other C-type assemblies sequentially. The structure at this point is as follows: Figure 9 As shown.

[0047] Step 11: Install the stringer end pressure plate 2-4 on the stringer end positioning strip 2-2 using the positioning pin 2-5. During installation, insert the vertical edges of adjacent C-shaped assemblies and the vertical edges of adjacent C-shaped and L-shaped assemblies into the grooves on the stringer end pressure plate 2-4, and press the parts between the grooves onto the horizontal ends of the C-shaped and L-shaped assemblies respectively to achieve the clamping of the C-shaped and L-shaped assemblies. After installation, check the stringer assembly according to the theoretically reserved gap.

[0048] Step 12: Remove connecting block 3-7, L-shaped occupant piece 3-10 and long stringer combination clamp 3-9.

[0049] Step 13: Sequentially cover the device surface with an isolation membrane, breathable felt, and vacuum bag. The encapsulation materials are overlapped to avoid bridging. Use sealing strips to bond the vacuum bag to the skin forming mold 2. Expel the air from the bag through the vacuum nozzle and put it into a thermostatic jar to complete the curing of the parts.

[0050] Step 14: After curing, remove the vacuum bag and other auxiliary materials, and then remove the stringer end pressure plate 2-4, stringer end positioning strip 2-2, and stringer side positioning strip 2-3 in sequence. Remove each stringer flexible pressure mold 3 in sequence from the edge to the middle.

[0051] Step 15: Reinstall the stringer end positioning strip 2-2 and stringer end pressure plate 2-4, and check the stringer position accuracy. After the accuracy meets the requirements, remove the stringer end positioning strip 2-2 and stringer end pressure plate 2-4, and demold the entire stringer skin integrated wall panel. After demolding, cut the skin and stringer allowance to the net size to obtain the high-precision stringer skin integrated wall panel 1.

[0052] Example: This embodiment takes a long stringer skin integrated wall panel 1 as an example. The wall panel is about 4000mm long, about 3000mm wide, and about 200mm high. There are 13 long strings with a spacing of about 200mm. The aerodynamic outer surface 1-1 is the outer surface of the part. The part is composed of skin ply 1-2, stringer ply 1-3 and 0 degree fiber 1-4. The long strings exist in the form of long stringer blanks 1-5 with surplus during plying and assembly. After curing, they are cut to the final size.

[0053] The specific parameters of the molding device are as follows: the main body of the skin molding mold 2 is made of INVAR steel; a 10mm gap is reserved between the end plate 2-4 of the stringer and the vertical edge of the L-shaped rigid limiting plate 3-1.

[0054] In the long stringer flexible pressure mold 3, the L-shaped rigid limiting pressure plate 3-1 is made of INVAR steel, and the combined gap between the vertical edges of adjacent L-shaped rigid limiting pressure plates 3-1 is 0.3mm; the long stringer clearance groove 3-2 is smaller than the L-shaped rigid limiting pressure plate 3-1, and the distance between its ends in the length direction is about 40mm; the top of the vertical edges of both the L-shaped long stringer blank 1-5 and the C-shaped long stringer blank 1-5 have a 20mm allowance; the flexible pressure pad 3-4 is made of silicone rubber, and the adhesive layer 3-3 is made of J-168 epoxy modified material. The adhesive, adhesive layer 3-3, flexible pressure pad 3-4, and the combined thickness of L-shaped stringer blank 1-5 / C-shaped stringer blank 1-5 are greater than the depth of stringer clearance groove 3-2 by no more than 1 mm; the air guide groove 3-5 is 5 mm wide, with its edge approximately 5 mm from the stringer clearance groove 3-2; the air guide rope 3-6 is a polytetrafluoroethylene fiber air guide rope matching the size of the air guide groove 3-5; the joint of the two L-shaped rigid limiting pressure plates 3-1 used in the C-shaped stringer blank 1-5 is a bevel fit, with a 0.3 mm gap reserved at the joint. The curing process parameters are 180℃ and 0.6 MPa.

[0055] The usage method is as described in steps 1 to 15 of Part 2, and will not be repeated here.

[0056] This invention provides a molding device for a high-precision integrated composite material panel with a stringer skin. It organically combines rigid and flexible components. An L-shaped rigid limiting pressure plate precisely controls the stringer's axial position, while a flexible pressure pad utilizes the difference in thermal expansion coefficients during curing to achieve uniform pressure on the stringer blank, ensuring the internal quality of the part. This device solves the problem of traditional "rigid-to-rigid" devices, which, while achieving high external precision, suffer from poor internal quality. It also overcomes the shortcomings of flexible devices, which, while providing good internal pressure transmission, generally have lower external precision. Furthermore, it is easy to operate and has high manufacturing efficiency. This invention can be widely applied in the field of composite material parts manufacturing technology.

[0057] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An apparatus for forming high-precision integrated composite wall panels with stringer skin, characterized in that, Includes skin forming mold (2) and stringer flexible pressure mold (3) that works with it; The main body of the skin forming mold (2) is the same process surface (2-1) as the aerodynamic outer surface (1-1) of the wall panel. The outer side of the process surface (2-1) is provided with a long string end positioning strip (2-2) and a long string side positioning strip (2-3). After the long string flexible pressure mold (3) is assembled on the process surface (2-1), the long string end pressure plate (2-4) is used to realize the positioning and pressing of the long string flexible pressure mold (3). The stringer flexible pressure mold (3) includes multiple L-shaped rigid limiting pressure plates (3-1); the stringer relief groove (3-2) is machined on the vertical side and horizontal bottom of the L-shaped rigid limiting pressure plate (3-1) to form a working surface for cooperating with the inner surface of the L-shaped stringer blank (1-5) and the C-shaped stringer blank (1-5); a flexible pressure pad (3-4) is set in the stringer relief groove (3-2), and the vertical plates of adjacent L-shaped rigid limiting pressure plates (3-1) are fixed together by the stringer combination clamp (3-9).

2. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, The stringer end pressure plate (2-4) is positioned and connected to the inner side of the stringer end positioning stop (2-2) by the positioning pin (2-5) for flattening and fixing the stringer flexible pressure mold (3); the stringer end pressure plate (2-4) is provided with multiple grooves spaced apart to make way for the vertical edge of the L-shaped rigid limiting pressure plate (3-1); the part between the grooves presses against the horizontal end of the L-shaped rigid limiting pressure plate (3-1).

3. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, A gap is reserved between the end plate of the long stringer (2-4) and the vertical edge of the L-shaped rigid limiting plate (3-1); a gap is reserved between the splice joints of a set of L-shaped rigid limiting plates (3-1) corresponding to the C-shaped long stringer blank (1-5); a gap is reserved between the vertical plates of adjacent L-shaped rigid limiting plates (3-1).

4. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, The flexible pressure pad (3-4) is bonded to the surface of the stringer relief groove (3-2) through the adhesive layer (3-3) and is used to apply flexible pressure to the L-shaped stringer blank (1-5) and C-shaped stringer blank (1-5) during curing; the coefficient of thermal expansion of the flexible pressure pad (3-4) is greater than that of the L-shaped rigid limiting pressure plate (3-1).

5. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, An air guide groove (3-5) is designed around the long stringer relief groove (3-2) on the upper edge of the L-shaped rigid limiting pressure plate (3-1). A replaceable air guide rope (3-6) is placed in the air guide groove (3-5) to release the vacuum during curing.

6. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, For the two L-shaped stringer blanks (1-5) on both sides of the integrated stringer skin panel (1), an L-shaped rigid limiting plate (3-1) is used for assembly. The horizontal edge of this L-shaped rigid limiting plate (3-1) is a straight edge, which directly matches the side positioning strip (2-3) of the stringer for positioning. For the remaining multiple C-shaped stringer blanks (1-5), each C-shaped stringer blank (1-5) needs to be assembled using a set of L-shaped rigid limiting plates (3-1). A set of L-shaped rigid limiting plates (3-1) are arranged opposite each other and are assembled into a U-shaped structure. They are connected and fixed by connecting blocks (3-7) and screws (3-8).

7. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, The long stringer combination clamp (3-9) includes a C-clamp (3-9-1) and a tightening handle (3-9-2); the C-clamp (3-9-1) is straddling the outside of the vertical edges of two adjacent L-shaped rigid limiting pressure plates (3-1). By rotating the tightening handle (3-9-2), the clamping jaws of the C-clamp (3-9-1) are narrowed, applying opposing pressure to the two L-shaped rigid limiting pressure plates (3-1).

8. The apparatus for forming high-precision long stringer skin integrated composite wall panels according to claim 1, characterized in that, When the long stringer combination clamp (3-9) is tightened, an L-shaped spacer (3-10) is set between the vertical edges of the two L-shaped rigid limiting pressure plates (3-1).

9. A method for molding high-precision long stringer skin integrated composite wall panels, characterized in that, Based on the apparatus according to any one of claims 1-8, it comprises: Step 1: Lay up the skin layers (1-2) on the process surface (2-1) of the skin forming mold (2); Step 2: Using positioning pins (2-5) and tightening bolts (2-6), the end positioning strip (2-2) and the side positioning strip (2-3) of the stringer are assembled onto the main body of the skin forming mold (2) and around the process surface (2-1). Step 3: The L-shaped stringer blanks (1-5) on both sides of the pre-formed and stacked stringer skin integrated wall panel (1) are assembled into the stringer clearance groove (3-2) of the corresponding L-shaped rigid limiting pressure plate (3-1). The L-shaped stringer blanks (1-5) are separated from the flexible pressure pad (3-4) by the isolation film, and the L-shaped stringer blanks (1-5) are fixed with contactable tape to obtain the L-shaped assembly. Step 4: Assemble the two assembled L-shaped assemblies onto both sides of the process surface (2-1). The length and width directions of the L-shaped rigid limiting pressure plate (3-1) are respectively aligned and positioned with the end positioning strip (2-2) of the stringer and the side positioning strip (2-3) of the stringer. Step 5: Fill the R-corner area of ​​the L-shaped stringer blank (1-5) of the L-shaped assembly with the pre-formed 0-degree fiber (1-4) from the side and compact it to complete the assembly of the L-shaped rigid limiting pressure plate (3-1) on both sides and the two L-shaped stringer blanks (1-5). Step 6: On the inner side of the L-shaped assembly on one side, assemble a set of L-shaped rigid limiting plates (3-1) corresponding to the first C-shaped stringer blank (1-5); the set of L-shaped rigid limiting plates (3-1) are arranged opposite each other and assembled into a U-shaped structure; Step 7: Assemble the C-shaped stringer blank (1-5) that has been laid up and preformed into the stringer clearance groove (3-2) in the fixed U-shaped structure. Separate the C-shaped stringer blank (1-5) from the flexible pressure pad (3-4) with the release film, and fix the C-shaped stringer blank (1-5) with the contactable tape to obtain the C-shaped assembly. Step 8: Assemble the C-type assembly onto the process surface (2-1) near the L-type assembly. Align the C-type assembly with the end positioning strip (2-2) of the stringer along its length and with the L-type rigid limiting plate (3-1) of the C-type assembly in its width direction. Insert an L-type spacer (3-10) in the middle to maintain a gap between the two. Install the stringer assembly clamp (3-9) on the vertical edge of the adjacent L-type rigid limiting plate (3-1). Step 9: Fill the R-corner area of ​​the L-shaped stringer blank (1-5) of the C-shaped assembly with the pre-formed 0-degree fiber (1-4) from the side and compact it; complete the assembly of the first C-shaped assembly; Step 10: Following the same method as steps 6 to 9, assemble all other C-type assemblies in sequence; Step 11: Install the stringer end pressure plate (2-4) on the stringer end positioning strip (2-2) using the positioning pin (2-5); Step 12: Remove the connecting block (3-7), L-shaped spacer piece (3-10), and long stringer combination clamp (3-9); Step 13: Sequentially cover the device surface with an isolation film, breathable felt, and vacuum bag. The sealing material is overlapped. Use sealing strips to bond the vacuum bag to the skin forming mold (2) around it. Expel the air from the bag through the vacuum nozzle and put it into the autoclave to complete the curing of the parts. Step 14: After curing, remove the end platen (2-4), end positioning strip (2-2), and side positioning strip (2-3) of the stringer. Remove each stringer flexible pressure mold (3) from the edge to the middle.

10. The method for forming a high-dimensional precision long stringer skin integrated composite wall panel according to claim 9, characterized in that, The method further includes: Step 15: Reinstall the stringer end positioning strip (2-2) and stringer end pressure plate (2-4) and check the stringer position accuracy. After the accuracy meets the requirements, remove the stringer end positioning strip (2-2) and stringer end pressure plate (2-4), demold the stringer skin integrated wall panel as a whole, and cut the skin and stringer allowance to the net size after demolding to obtain the processed stringer skin integrated wall panel (1).

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