A curvature-variable, multi-sag, long-size J-shaped rib solidification forming process and device

Abstract

The present invention relates to the technical field of composite material manufacturing, and specifically discloses a variable curvature, multi-sag, long-size J-shaped rib curing molding process and device, including a C-shaped paving mold, a Z-shaped paving mold and an edge strip paving mold made of metal material. The present invention adopts an integral metal tooling molding process to replace the molding process of a metal mold and a composite mold or a metal mold and a silicone rubber mold, adopts an integral metal tooling posture to drive the product under the curing pressure, and at the same time uses the C-shaped paving mold to increase the component of its own gravity and coordinate with the Z-shaped paving mold to ensure the molding quality of the R corner area and the surface contour of the edge strip surface.

Description

Technical Field

[0001] The invention relates to the technical field of composite material manufacturing, and in particular to a curing and forming process and a device for a J-shaped rib with variable curvature, multiple depressions and long size. Background Art

[0002] Carbon fiber composite materials have the advantages of high specific strength, high specific stiffness, excellent corrosion resistance, strong designability, and good fatigue fracture resistance. They have gradually become the main structural materials for the new generation of aircraft at home and abroad. Composite reinforced panel structures are widely used in main load-bearing structures such as large wings and fuselages due to their good post-buckling bearing capacity and weight reduction effects. J-ribbed panels mostly use secondary bonding technology, so the profile and internal quality of the J-ribbed panels themselves are particularly important;

[0003] At present, composite J-shaped bars are mostly made of unidirectional tape materials, and most of them are straight or single-curved structures, and the J-shaped bar edge strip surface is uniform, and most of them have no sinking area. In the existing J-shaped bar manufacturing process, the molding process of metal mold and composite mold and metal mold and silicone rubber mold is mostly used. However, for the curved structure edge strip surface with more sinking areas and longer length (J-shaped bar structure with arc length greater than 1800mm), the difficulty of paving this structure itself is increased, resulting in the J-shaped bar R corner area, especially in the edge strip sinking area, bridging phenomenon is very easy to occur during the paving process, resulting in delamination after curing. At the same time, if metal and composite molds or metal and silicone rubber molds are used, due to the deformation of the composite mold or silicone rubber mold itself and deformation after use, the thick composite mold or silicone rubber mold is difficult to position with the metal main mold, and the matching between the two parts of the J-shaped bar cannot be guaranteed, resulting in delamination or pores in the R corner after the J-shaped bar is cured. At the same time, the service life of the composite mold or silicone rubber mold is low (less than 3 times), which greatly increases the cost. Therefore, it is increasingly important to find a method that can ensure the internal and external quality of long-sized composite J-shaped ribs with variable curvature and multiple depressions.

[0004] Through the above analysis, the problems and defects of the prior art can be summarized as follows:

[0005] (1) In the prior art, metal mold + composite mold or metal mold + silicone rubber mold is often used to form composite J-shaped ribs. This method is mostly suitable for straight or single-curved structures, uniform J-shaped rib edge strip surface, mostly without sink areas and with a small number of laying layers. For composite J-shaped ribs with variable curvature, multiple sink areas and long dimensions, the composite mold or silicone rubber mold for auxiliary molding of the Z-shaped part preform deforms itself and deforms after use, resulting in poor fit of the edge strip surface, affecting the internal and external quality of the parts;

[0006] (2) It cannot be avoided that the prepreg is in an uncured state. Since the resin inside the composite material does not flow fully, the overall thickness of the uncured part is thicker than the thickness after curing. In particular, the size of the R angle deviates from the theoretical size, which makes it easy to form a cavity in the R angle area after the C-shaped part and the Z-shaped part are positioned and installed, causing internal defects;

[0007] (3) Composite material J-shaped bars are mostly made of unidirectional tape materials, which makes it difficult to lay them out as a whole for long structures with variable curvature and many depressions. After curing in the autoclave, wrinkles, bridges, and voids are likely to form on the side close to the vacuum bag. Summary of the invention

[0008] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a variable curvature, multi-sag, long-size J-shaped rib curing molding process and device.

[0009] To achieve the above object, the present invention provides the following technical solution: a curvature-variable, multi-sag, long-size J-shaped rib solidification molding process, comprising the following steps:

[0010] S1, laying carbon fiber materials on a C-type laying mold, a Z-type laying mold and an edge strip laying mold, laying carbon fiber unidirectional tape on a composite material twist strip forming mold, and packaging and hot pressing them in a vacuum bag to obtain a C-type preform, a Z-type preform, an edge strip preform and a carbon fiber unidirectional tape twist strip respectively;

[0011] S2, positioning and installing the C-shaped paving mold and the Z-shaped paving mold through the positioning baffle to obtain a first assembly;

[0012] S3, packaging the first assembly with a vacuum bag and performing vacuum compaction, then filling the carbon fiber unidirectional twisted strips into the R corner area of ​​the first assembly, and combining the edge strip paving mold with the first assembly through a positioning baffle and a positioning rib to obtain a second assembly;

[0013] S4. The second assembly is packaged in a vacuum bag and vacuum compacted, the positioning baffle is removed, and the edge of the peripheral contour of the part is protected by unvulcanized rubber. Finally, it is packaged in a vacuum bag, cured in an autoclave, and demoulded to obtain a molded product.

[0014] Preferably, in S3, after the first assembly is vacuum compacted, carbon fiber unidirectional tape filaments are first used for pre-filling, and then carbon fiber unidirectional tape twisted strips are filled into the R corner area of ​​the first assembly, and after filling, the local cavity position is filled with carbon fiber filaments.

[0015] The present invention also provides a curvature-variable, multi-sag, long-size J-shaped rib solidification and molding device, comprising:

[0016] A C-type laying mold, used for laying carbon fiber materials of a C-type preform;

[0017] A Z-type laying mold is used to lay the carbon fiber material of the Z-type preform and to combine and position it with the C-type laying mold;

[0018] The edge strip laying mold is used for laying the carbon fiber material of the edge strip preform and pressurizing and curing the edge strip surface. The inner wall of the edge strip laying mold is provided with a plurality of protrusions along the arc length direction thereof for forming a depression of the edge strip surface;

[0019] C-type paving molds, Z-type paving molds and edge strip paving molds are all made of metal.

[0020] Preferably, a positioning baffle is provided on the Z-shaped paving mold for installation and positioning with the C-shaped paving mold, and the degree of freedom of the C-shaped paving mold and the edge strip paving mold in the length direction is constrained by the positioning baffle.

[0021] Preferably, the edge strip paving mold is positioned and installed by means of a positioning rib provided on the Z-shaped paving mold.

[0022] The present invention also proposes a curvature-variable, multi-sag, long-size J-shaped rib solidification molding process, which is applied to the above-mentioned device and includes the following steps:

[0023] S1, laying carbon fiber materials on a C-type laying mold, a Z-type laying mold and an edge strip laying mold, laying carbon fiber unidirectional tape on a composite material twist strip forming mold, and packaging and hot pressing them in a vacuum bag to obtain a C-type preform, a Z-type preform, an edge strip preform and a carbon fiber unidirectional tape twist strip respectively;

[0024] S2, positioning and installing the C-shaped paving mold and the Z-shaped paving mold through the positioning baffle to obtain a first assembly;

[0025] S3, packaging the first assembly with a vacuum bag and performing vacuum compaction, then filling the carbon fiber unidirectional twisted strips into the R corner area of ​​the first assembly, and combining the edge strip paving mold with the first assembly through a positioning baffle and a positioning rib to obtain a second assembly;

[0026] S4. The second assembly is packaged in a vacuum bag and vacuum compacted, the positioning baffle is removed, and the edge of the peripheral contour of the part is protected by unvulcanized rubber. Finally, it is packaged in a vacuum bag, cured in an autoclave, and demoulded to obtain a molded product.

[0027] Preferably, in S1, the C-type preform and the Z-type preform are hot compacted separately by using an autoclave, the pressure is controlled at 0.3 MPa to 0.6 MPa, and a breathable felt is used to guide air to the R corner area during the hot compaction process.

[0028] Preferably, in S3, the vacuum pressure of the first assembly during vacuum compaction is not less than -0.08 MPa.

[0029] Preferably, after the first assembly is vacuum compacted, carbon fiber unidirectional tape filaments are first used for pre-filling, and then carbon fiber unidirectional tape twisted strips are filled into the R corner area of ​​the first assembly, and after filling, carbon fiber filaments are used to fill the local cavity position.

[0030] Preferably, the step difference between the C-type preform and the Z-type preform is no more than 0.1 mm.

[0031] In addition, the present invention also proposes a J-shaped rib with variable curvature, multiple depressions and long size. The product is made by the process or device mentioned above. The arc length of the J-shaped rib is 1850mm, the wall thickness is 3mm, and there are a total of five depressions on the edge surface.

[0032] Compared with the prior art, the present invention provides a curvature-variable, multi-sag, long-size J-shaped rib curing forming process, which has the following beneficial effects:

[0033] (1) The present invention adopts an integral metal tooling forming process to replace the forming process of a metal mold and a composite mold or a metal mold and a silicone rubber mold, and simultaneously adopts layer-by-layer laying and vacuum compaction to effectively improve the compaction degree of the R corner and the sunken position. At the same time, after the C-type part and the Z-type part preform are laid, hot compaction is performed in an autoclave, and breathable felt is used to strengthen the air conduction of the R corner area during the hot compaction process, thereby promoting the flow of resin in the R corner area during the process, thereby promoting uniform thickness of the R corner area, improving the fit degree of the R corner area during the positioning and assembly process of the C-type part and the Z-type part, and avoiding the risk of cavity formation in the R corner area and causing internal defects.

[0034] (2) The part adopts an overall metal tooling posture, which releases the freedom of the C-type partial paving mold in the gravity direction. At the same time, a positioning baffle is set in the length direction. While releasing gravity, it effectively limits the freedom in the length direction to ensure the overall positioning accuracy. After the C-type preform and the Z-type preform are positioned and combined, vacuum compaction is added and the step difference control of the C-type preform and the Z-type preform on the edge strip side is increased. The step difference range is controlled within 0.1mm, and the local position of the step difference is filled with unidirectional tape material for transition. This tooling posture increases the effect of the gravity component in the R corner area during the positioning and combination process of the C-type preform and the Z-type preform and the curing process. At the same time, with the help of the external pressure of the autoclave and the negative pressure in the vacuum bag during the product curing process, the C-type partial paving mold and the Z-type paving mold are coordinated to avoid the formation of cavities in the R corner area. This ensures the molding quality of the R corner area and the profile of the edge strip surface.

[0035] (3) In addition, by using the curing molding device of the present invention, the R corner area of ​​the J-shaped rib of the composite material is in contact with the molding tool surface, reducing the contact with the vacuum bag. The compaction degree of the R corner area is enhanced by the three external forces of the tooling's own gravity component, the external curing pressure of the autoclave, and the negative pressure in the vacuum bag. The above two methods improve the molding quality of the R corner area and avoid the situation where wrinkles, bridges, and pores are easily generated on the side close to the vacuum bag.

[0036] (4) The composite material J-shaped rib prepared by the method proposed in the present invention has an arc length of 1850 mm, an overall arc-shaped structure, a total of 5 depressions on the edge strip surface, and a J-shaped rib wall thickness of 3 mm. This breaks through the conventional structural form in the industry that the J-shaped rib structure is a straight or single-curved structure, the J-shaped rib edge strip surface is uniform, most of them have no depression area, and the J-shaped rib thickness is thin, and solves the manufacturing problem of J-shaped ribs with variable curvature, multiple depressions, and long sizes of composite materials.

[0037] (5) The present invention adopts metal molds as a whole, which greatly increases the service life. It can reach at least 200 molds under high temperature and high pressure conditions, thereby reducing the manufacturing cost.

[0038] (6) In addition, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following: the technical solution used in the present invention is a research object of a long composite material J-shaped rib with variable curvature and multiple depressions. Composite material J-shaped ribs are widely used as reinforcement ribs in the aerospace field in structures such as aircraft wings, fuselages, and tail fins. At present, the structure of composite material J-shaped ribs in China is mostly straight or single-curved, the J-shaped rib edge strip surface is uniform, most of them have no depression area, and the thickness of the J-shaped ribs is relatively thin. In addition, the traditional composite material J-shaped ribs are prone to wrinkles, bridges, pores and other defects at the R angle, and the product quality is unstable. The curing and molding device and solution of the composite material J-shaped rib of the present invention effectively improves the problems of wrinkles, bridges, pores and other problems at the traditional R angle, and solves the problems of deformation of the composite tooling or silicone rubber mold itself and deformation after use of the Z-shaped part of the composite material J-shaped rib. The solution is reliable and stable. At present, the solution has been verified on a certain type of main load-bearing product and can be applied to batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 A schematic diagram of a curing and molding device at a first angle in an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of a curing and molding device from another angle in an embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of the structure of the curing and molding device after being decomposed at a first angle in an embodiment of the present invention;

[0043] Figure 4 It is a schematic structural diagram of another angle after the curing and molding device in the embodiment of the present invention is decomposed;

[0044] Figure 5 Schematic diagram of the composite material J-shaped rib forming process in an embodiment of the present invention;

[0045] Figure 6 is a cross-sectional schematic diagram of a first assembly in an embodiment of the present invention;

[0046] Figure 7 is a cross-sectional schematic diagram of a second assembly in an embodiment of the present invention;

[0047] Figure 8 Schematic diagram of the cross section of the sunken area of ​​the edge strip surface in the embodiment of the present invention;

[0048] Fig. 9 Schematic diagram of the structure of the J-shaped rib in an embodiment of the present invention.

[0049] Among them, 01, C-type paving mold; 02, Z-type paving mold; 03, edge strip paving mold; 04, positioning baffle; 05, positioning retaining edge; 06, bolt; 07, lifting eye hole; 08, R corner area; 09, edge strip surface depression. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0051] This embodiment provides a curvature-varying, multi-depression, long-size J-shaped rib solidification forming device, such as Figure 1-Figure 4 As shown, the device includes:

[0052] C-type laying mold 01, which is used to lay carbon fiber materials of C-type preform;

[0053] The Z-type laying mold 02 is used for laying the carbon fiber material of the Z-type preform and for positioning in combination with the C-type laying mold 01;

[0054] The edge strip paving mold 03 is used for paving the carbon fiber material of the edge strip preform and pressurizing and curing the edge strip surface. The inner wall of the edge strip paving mold 03 is distributed along the arc length direction with several protrusions for forming the edge strip surface depression 09; the Z-type paving mold 02 is provided with a positioning baffle 04 installed and positioned with the C-type paving mold 01. Since the device in the present invention is suitable for the production of long-sized parts, the overall weight of the tooling is heavy and requires the assistance of an external lifting device. Therefore, two lifting ring holes 07 are opened on the outer wall of the Z-type paving mold 02 to facilitate the lifting device to suspend the tooling. The length direction of the C-type paving mold 01 and the edge strip paving mold 03 is constrained by the positioning baffle 04. The edge strip paving mold 03 is positioned and installed by the positioning retaining edge 05 provided on the Z-type paving mold 02.

[0055] C-type paving mold 01, Z-type paving mold 02 and edge strip paving mold 03 are all made of metal. The overall metal tooling posture is driven by the product under the curing pressure. At the same time, the C-type paving mold increases the component of its own gravity and coordinates with the Z-type paving mold to ensure the molding quality of the R corner area and the profile of the edge strip surface. In addition, the entire device uses a metal mold, which greatly increases the service life of the tooling and reduces the overall manufacturing cost of the parts.

[0056] The specific process of using the above device to prepare variable curvature, multiple depressions, and long-sized J-shaped ribs is as follows: Figure 5-8 As shown, the following steps are included:

[0057] S1. First, lay carbon fiber materials on C-type laying mold 01, Z-type laying mold 02 and edge strip laying mold 03, and lay carbon fiber unidirectional tape on the composite material twist strip forming mold. Among them, the actual filling amount width of the unidirectional tape is obtained by dividing the theoretical cavity cross-sectional surface area by the thickness of the unidirectional tape material to obtain the theoretical width, and the theoretical width multiplied by 1.15 to 1.25 is the actual unidirectional tape filling amount. In this embodiment, the R angle radius of the inner side of the J-type rib is 3mm, the wall thickness of the J-type rib is 3mm, and the thickness of the unidirectional tape single layer is 0.125mm, then the R angle area 08 needs to be filled with unidirectional tape material with a width of 83.6mm. Subsequently, vacuum bags are used for packaging and hot compaction to obtain C-type preforms, Z-type preforms, edge strip preforms and carbon fiber unidirectional tape twist strips respectively. Among them, the C-type preform and the Z-type preform are hot compacted separately by autoclave, and the pressure is controlled at 0.3MPa~0.6MPa. Breathable felt is used to guide air to the R corner area 08 during the hot compaction process to promote the flow of resin in the R corner area 08 during the process, thereby promoting uniform thickness in the R corner area 08, improving the fit between the C-type part and the Z-type part in the R corner area 08 during the positioning and assembly process, and avoiding the risk of cavity formation in the R corner area 08 and causing internal defects.

[0058] S2. Position and install the C-shaped paving mold 01 and the Z-shaped paving mold 02 through the positioning baffle 04 to obtain a first assembly. The positioning baffle 04 connects and fixes the C-shaped paving mold 01 and the Z-shaped paving mold 02 through bolts 06.

[0059] S3. The first assembly is packaged in a vacuum bag and vacuum compacted, and the vacuum pressure is not less than -0.08MPa. At the same time, the step difference between the C-type preform and the Z-type preform on one side of the edge strip surface is controlled, and the step difference range is controlled within 0.1mm. After compaction, in order to ensure that the sharp corner position of the R corner area 08 in the first assembly is completely filled, carbon fiber unidirectional tape filaments are first used for pre-filling, and then the carbon fiber unidirectional tape twisted strips are raised and filled into the R corner area 08 of the first assembly. After filling, the local cavity position is filled with carbon fiber filaments, and then the edge strip paving mold 03 is combined with the first assembly through the positioning baffle 04 and the positioning retaining edge 05 to obtain the second assembly.

[0060] S4. The second assembly is packaged in a vacuum bag and vacuum compacted, the positioning baffle 04 is removed, and the edge of the peripheral contour of the part is protected by unvulcanized rubber. Finally, it is packaged in a vacuum bag, cured in an autoclave, and demolded to obtain a molded product.

[0061] The products prepared by the above-mentioned device and the above-mentioned process are as follows Fig. 9 As shown, its specifications are: the arc length of the J-shaped rib is 1850mm, the wall thickness is 3mm, and there are a total of five edge surface depressions of 09 on the edge surface.

[0062] In the description of the present invention, the terms "first", "second", "another", and "yet another" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0063] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0064] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A curing and forming process for J-shaped ribs with variable curvature, multiple depressions and long dimensions, characterized in that: The process is completed by a molding device, which includes: A C-type laying mold (01), used for laying the carbon fiber material of the C-type preform; A Z-shaped paving mold (02) is used for paving the carbon fiber material of the Z-shaped preform and for positioning in combination with the C-shaped paving mold (01); The edge strip laying mold (03) is used for laying the carbon fiber material of the edge strip preform and pressurizing and curing the edge strip surface. The inner wall of the edge strip laying mold (03) is provided with a plurality of protrusions distributed along the arc length direction thereof for forming edge strip surface depressions (09); The C-shaped paving mold (01), the Z-shaped paving mold (02) and the edge strip paving mold (03) are all made of metal; A positioning baffle (04) is provided on the Z-shaped paving mold (02) for mounting and positioning with the C-shaped paving mold (01), and the degree of freedom in the length direction of the C-shaped paving mold (01) and the edge strip paving mold (03) is constrained by the positioning baffle (04); The edge strip paving mold (03) is positioned and installed by means of a positioning retaining edge (05) provided on the Z-shaped paving mold (02); The steps of the molding process are as follows: S1, laying carbon fiber materials on a C-type laying mold (01), a Z-type laying mold (02) and an edge strip laying mold (03), laying a carbon fiber unidirectional tape on a composite material twist strip forming mold, packaging with a vacuum bag and hot compacting to obtain a C-type preform, a Z-type preform, an edge strip preform and a carbon fiber unidirectional tape twist strip, respectively, wherein the C-type preform and the Z-type preform are hot compacted in an autoclave, the pressure is controlled at 0.3MPa to 0.6MPa, and a breathable felt is used to guide air to the R corner area (08) during the hot compaction process; S2, positioning and installing the C-shaped paving mold (01) and the Z-shaped paving mold (02) through the positioning baffle (04) to obtain a first assembly; S3, packaging the first assembly with a vacuum bag and performing vacuum compaction, then filling the carbon fiber unidirectional twisted strips into the R corner area (08) of the first assembly, and combining the edge strip laying mold (03) with the first assembly through the positioning baffle (04) and the positioning retaining edge (05) to obtain a second assembly; S4. The second assembly is packaged with a vacuum bag and vacuum compacted, the positioning baffle (04) is removed, the peripheral contour of the part is edge-guarded with unvulcanized rubber, and finally, it is packaged with a vacuum bag, cured in an autoclave, and demoulded to obtain a molded product.

2. The curing and forming process of a J-shaped rib with variable curvature, multiple depressions and long dimensions according to claim 1, characterized in that: In S3, the vacuum pressure of the first assembly is not less than -0.08 MPa during vacuum compaction.

3. A curing and forming process for J-shaped ribs with variable curvature, multiple depressions and long dimensions according to claim 2, characterized in that: After the first assembly is vacuum compacted, it is pre-filled with carbon fiber unidirectional tape filaments, and then the carbon fiber unidirectional tape twist strips are filled into the R corner area of ​​the first assembly, and after filling, the local cavity position is filled with carbon fiber filaments.

4. The curing forming process of a J-shaped rib with variable curvature, multiple depressions and long dimensions according to claim 3, characterized in that: The step difference between the C-type preform and the Z-type preform is no more than 0.1 mm.

5. A J-shaped rib with variable curvature, multiple depressions and long dimensions, obtained by the process described in any one of claims 1 to 4, characterized in that: The arc length of the J-shaped rib is 1850 mm, the wall thickness is 3 mm, and there are a total of five edge depressions on the edge surface (09).

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