A co-curing molding process for composite material U-shaped long stringer reinforced wall panels

Abstract

The present invention discloses a co-curing molding process for a composite material U-shaped long stringer reinforced wall panel: S1, providing a long stringer paving mold and a skin paving mold; the long stringer paving mold includes a plurality of first molds and a second mold; S2, paving long stringer prepreg on the first mold and the second mold, and then pre-compacting; removing the prepreg paved on the second mold to obtain a long stringer preformed product; S3, paving prepreg and adhesive film on the skin paving mold; fixing the pre-compacted first mold on the skin paving mold, and reserving a gap between adjacent first molds for placing the long stringer preformed product; S4, placing the preformed product in the gap; S5, paving a pressure pad on the surface of the pre-compacted first mold and the long stringer preformed product; S6, paving a vacuum auxiliary material on the outside of the pressure pad for bagging, curing, and demoulding to obtain a composite material U-shaped long stringer reinforced wall panel blank; S7, machining the blank to form a beveled end at the end of the long stringer to obtain a composite material U-shaped long stringer reinforced wall panel.

Description

Technical Field

[0001] The invention relates to the technical field of composite material manufacturing, and in particular to a co-curing molding process for a composite material U-shaped long-string reinforced wall panel. Background Art

[0002] Common structural forms of composite reinforced wall panels include T-shaped long stringer reinforced wall panels, hat-shaped long stringer reinforced wall panels, J-shaped long stringer reinforced wall panels, I-shaped long stringer reinforced wall panels, etc. Reinforced wall panels with this type of structure generally adopt molding processes such as co-bonding and secondary bonding, which makes it difficult to achieve integrated molding of the stringers and the skin. U-shaped long stringer reinforced wall panels have multiple advantages such as a large number of stringers, good weight reduction effect, smooth load transfer, low manufacturing cost, good stability, and good fatigue resistance. The co-curing integral molding process has the advantage of a larger bonding area between the stringers and the wall panels, which can effectively avoid debonding of the stringers and improve structural strength. The U-shaped long stringer reinforced wall panels prepared by the co-curing molding method provide a very critical technology for the application of composite materials in large aircraft.

[0003] However, the existing forming technology has the following defects: (1) T-shaped long girder reinforced wall panels, hat-shaped long girder reinforced wall panels, J-shaped long girder reinforced wall panels, I-shaped long girder reinforced wall panels, etc. generally adopt forming processes such as co-bonding and secondary bonding, but the bonding parts of this process scheme are prone to delamination, which reduces the structural strength; (2) The existing forming process of U-shaped long girder reinforced wall panels uses metal molds, which are difficult to process and have high mold costs; (3) There is a poor fit between the long girder mold and the skin mold, which easily causes uneven pressure transmission and internal quality defects; (4) There are too many metal molds in the curing process, the temperature uniformity is poor, the heating and cooling rate of the composite material parts is slow and difficult to control, and it is easy to cause internal quality defects; (5) During the curing process, the mold is deformed due to the thermal expansion of the mold, which will cause long girder offset and dimensional deviation. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the existing composite material long-beam reinforced wall panel forming process and provide a composite material U-shaped long-beam reinforced wall panel co-curing forming process. The forming process of the present invention has low manufacturing cost. The composite material U-shaped long-beam reinforced wall panel manufactured by the forming process of the present invention has good stability and fatigue resistance, can effectively avoid the risk of long-beam debonding, and improve the structural strength of the product.

[0005] The present invention is achieved through the following technical solutions:

[0006] A co-curing molding process for a composite material U-shaped long stringer reinforced wall panel, characterized in that the composite material U-shaped long stringer reinforced wall panel comprises: a skin and a plurality of long strings arranged on the skin;

[0007] The long stringer and the skin are transitioned by an R angle, and the end of the long stringer is set as a bevel end;

[0008] The molding process includes the following steps:

[0009] S1. Provide several stringer laying molds and skin laying molds;

[0010] Wherein: the long stringer paving mold is used for paving to form a U-shaped long stringer, which includes a plurality of first molds and a plurality of second molds, and the first molds and the second molds have structures for forming R angles;

[0011] S2. Laying long stringer prepreg on the first mold and the second mold respectively, and pre-compacting after laying; after pre-compacting, removing the prepreg laid on the second mold to obtain a long stringer preform with a partial U-shaped structure;

[0012] S3. Laying skin prepreg on the skin laying mold, and laying adhesive film on the skin prepreg; fixing a plurality of pre-compacted first molds on the laid skin laying mold according to the arrangement positions of the long stringers, and reserving gaps between adjacent first molds just enough to accommodate the long stringer preforms;

[0013] S4, placing the long string preform in the gap, and filling twist strips at the R corner between the long string prepreg and the skin prepreg;

[0014] S5. Laying a pressure pad on the surfaces of the pre-compacted first mold and the long stringer preform;

[0015] S6, laying vacuum auxiliary material on the outside of the pressure pad to make bags, then curing and demoulding to obtain a composite material U-shaped long stringer reinforced wall panel blank;

[0016] S7. Machining the composite material U-shaped long stringer reinforced wall panel blank to form a beveled end at the end of the long stringer to obtain the composite material U-shaped long stringer reinforced wall panel.

[0017] Specifically, in the composite material U-shaped long stringer reinforced wall panel manufactured by the present invention, the value of the R angle is generally between R2 and R5, the height of the long stringer is between 10 and 100 mm, and the spacing between the long stringers is between 100 and 500 mm.

[0018] Specifically, in the co-curing molding process of the composite material U-shaped long truss reinforced wall panel provided by the present invention, a pressure pad (silicone pressure pad) is first laid on the side close to the vacuum bag, which is used to ensure uniform pressure transmission and improve the molding quality of the part surface close to the bag surface.

[0019] Furthermore, a co-curing molding process for a composite U-shaped stringer reinforced wall panel is provided: the skin prepreg and stringer prepreg are selected from carbon fiber prepreg, glass fiber prepreg, or Kevlar prepreg. The prepreg can be in the form of unidirectional tape, fabric, or a hybrid layup. The twisted strands are unidirectional prepreg.

[0020] Furthermore, a composite material U-shaped long truss reinforced wall panel co-curing molding process: the first mold is a metal material mold; the second mold is a wood substitute mold.

[0021] Specifically, the first mold can be made of steel, aluminum alloy or invar steel, which can meet the curing requirements of the composite material. The second mold can be made of a low-cost wood substitute mold, which can meet the pre-compacting requirements of the composite material.

[0022] Furthermore, a composite material U-shaped long truss reinforced wall panel co-curing molding process: the pre-compacting temperature in step S2 is 60-80° C., and the pre-compacting pressure is 0.1-0.3 MPa.

[0023] Furthermore, a composite material U-shaped long stringer reinforced wall panel co-curing molding process: the skin laying mold is provided with a laser projection positioning target for positioning when the skin prepreg is laid.

[0024] Specifically, the skin prepreg can be laid manually by laser projection, or by using an automatic tape laying machine or an automatic wire laying machine.

[0025] Furthermore, a co-curing molding process for a composite material U-shaped long-string reinforced wall panel is provided: the skin laying mold is provided with a positioning pin for fixing the first mold.

[0026] Furthermore, a composite material U-shaped long stringer reinforced wall panel co-curing molding process: the vacuum auxiliary materials described in step S6 include but are not limited to release cloth, isolation film, breathable felt, and vacuum bag.

[0027] Furthermore, a composite material U-shaped long stringer reinforced wall panel co-curing molding process: in step S6, the curing temperature is 120-140° C., and the curing pressure is 0.2-0.7 MPa.

[0028] Beneficial effects of the present invention:

[0029] (1) The composite U-shaped long-string reinforced wall panels manufactured by the molding process of the present invention have the advantages of a large number of long strings, good weight reduction effect, smooth load transfer, low manufacturing cost, good stability, and good fatigue resistance. The composite U-shaped long-string reinforced wall panels manufactured by the co-curing integral molding process adopted by the present invention have the advantage of a larger bonding area between the long strings and the wall panels, which can effectively avoid the problem of long stringer debonding and improve the structural strength of the resulting reinforced wall panels.

[0030] (2) In the molding process of the present invention, low-cost wood-substitute molds are used to replace expensive metal molds as part of the paving molds, which greatly reduces the manufacturing cost of the molds and reduces the production cost. In the curing molding process of the present invention, the first mold (i.e., the metal U-shaped long stringer molding mold) is set at intervals, which reduces the use of half of the metal molds and reduces the mold manufacturing cost. At the same time, it solves the problem of poor temperature uniformity caused by too many metal molds in the curing process, slow and difficult to control heating and cooling rates of composite materials, and easy to cause internal quality defects. That is, the molding process of the present invention improves the uniformity of the temperature field and ensures the molding quality of the product.

[0031] (3) In the present invention, the positioning accuracy of the long stringer is ensured by the positioning pins between the U-shaped long stringer mold (the first mold) and the skin laying mold; in the molding process of the present invention, a silicone pressure pad is also used to ensure uniform pressure transmission, meet the internal molding quality of the parts, and improve the molding quality of the surface of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic structural diagram of a composite material U-shaped long stringer reinforced wall panel manufactured by the present invention;

[0034] Figure 2 A schematic cross-sectional view of a composite material U-shaped long stringer reinforced wall panel manufactured by the present invention;

[0035] Figure 3 The structure of the long stringer laying mold used in the present invention and the schematic diagram of the long stringer prepreg laying; wherein: the first mold and the second mold have the same structure, the difference is that the two are made of different materials;

[0036] Figure 4 4 is a process flow chart of step S3 in the co-curing molding process of the present invention;

[0037] Figure 54 is a process flow chart of steps S4 to S6 in the co-curing molding process of the present invention.

[0038] Markings in the figure: 1 skin, 2 stringer, 3 stringer laying mold, 4 skin laying mold, 5 gap, 6 twist strip, 7 pressure pad, 8 vacuum auxiliary material, 9 R angle, 10 stringer preform, 1-1 skin prepreg, 2-1 bevel end, 2-2 stringer prepreg, 3-1 first mold, 3-2 second mold. DETAILED DESCRIPTION

[0039] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom" and the like to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Moreover, the terms "first", "second" and the like are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0041] Example 1

[0042] A co-curing molding process for a composite material U-shaped long stringer reinforced wall panel is provided, wherein the composite material U-shaped long stringer reinforced wall panel comprises: a skin 1 and a plurality of long strings 2 arranged on the skin 1;

[0043] The transition between the long stringer 2 and the skin 1 is made by an R angle 9, and the end of the long stringer 2 is set as a bevel end 2-1; the structure of the composite material U-shaped long stringer reinforced wall panel is as follows Figure 1 As shown;

[0044] The molding process includes the following steps:

[0045] S1. Provide several stringer laying molds 3 and skin laying molds 4;

[0046] The long stringer paving mold 3 is used to pave and form a U-shaped long stringer, which includes a plurality of first molds 3-1 and a plurality of second molds 3-2, and the second molds 3-2 are selected from wood substitute molds, and the first molds 3-1 and the second molds 3-2 have structures for forming R angles; the structure of the long stringer paving mold 3 is as follows Figure 3 As shown;

[0047] S2, respectively laying long stringer prepreg 2-2 on the first mold 3-1 and the second mold 3-2 (laying of long stringer prepreg is as follows) Figure 3 As shown), after laying, pre-compacting is performed at 60-80° C. and 0.1-0.3 MPa pressure; after pre-compacting, the prepreg laid on the second mold 3-2 is removed to obtain a long stringer preform 10 with a partial U-shaped structure;

[0048] S3, laying the skin prepreg 1-1 on the skin laying mold 4, laying the adhesive film on the skin prepreg 1-1; fixing a plurality of pre-compacted first molds 3-1 on the laid skin laying mold 4 according to the setting position of the long stringer 2 through positioning pins, and leaving a gap 5 (such as 5) between adjacent first molds 3-1 just for placing the long stringer preform 10. Figure 4 shown);

[0049] S4, placing the long string preform 10 in the gap 5, and filling the twist strip 6 (such as Figure 5 shown);

[0050] S5, laying a pressure pad 7 (such as Figure 5 As shown), by laying the pressure pad 7 (silicone pressure pad), the pressure is evenly transmitted, thereby improving the molding quality of the parts;

[0051] S6, laying vacuum auxiliary materials 8 (vacuum auxiliary materials include release cloth, isolation film, breathable felt, vacuum bag) on ​​the outside of the pressure pad 7 to seal the bag (such as Figure 5 As shown), and then cured at 120-140° C. and 0.2-0.7 MPa pressure, demoulding, to obtain a composite material U-shaped long stringer reinforced wall panel blank, the obtained;

[0052] S7, machining the composite material U-shaped long stringer reinforced wall panel blank, forming a beveled end 2-1 at the end of the long stringer 2, and obtaining a composite material U-shaped long stringer reinforced wall panel; the cross-sectional view or layer diagram of the obtained composite material U-shaped long stringer reinforced wall panel is as shown Figure 2 shown.

[0053] The molding process of the present invention has low manufacturing cost. The composite material U-shaped long girder reinforced wall panel manufactured by the molding process of the present invention has good structural stability and good fatigue resistance, can effectively avoid the risk of long girder debonding, and improves the structural strength of the product.

[0054] The above preferred embodiments of the present invention are only used to explain the present invention and are not used to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A co-curing molding process for composite material U-shaped long stringer reinforced wall panels, characterized in that: The composite material U-shaped long stringer reinforced wall panel comprises: a skin (1) and a plurality of long strings (2) arranged on the skin (1); The long stringer (2) and the skin (1) are transitioned by an R angle, and the end of the long stringer (2) is configured as a beveled end (2-1); The molding process includes the following steps: S1, providing a number of long stringer laying molds (3) and skin laying molds (4); The long stringer paving mold (3) is used for paving to form a U-shaped long stringer, and comprises a plurality of first molds (3-1) and a plurality of second molds (3-2), wherein the first molds (3-1) and the second molds (3-2) have structures for forming R angles; S2, laying long stringer prepreg (2-2) on the first mold (3-1) and the second mold (3-2), respectively, and pre-compacting after laying; after pre-compacting, removing the prepreg laid on the second mold (3-2), to obtain a long stringer preform (10) with a partial U-shaped structure; S3, laying a skin prepreg (1-1) on the skin laying mold (4), and laying a film on the skin prepreg (1-1); fixing a plurality of pre-compacted first molds (3-1) on the laid skin laying mold (4) according to the setting position of the long stringer (2), and reserving a gap (5) between adjacent first molds (3-1) just enough to place the long stringer preform (10); S4, placing the long string preform (10) in the gap (5), and filling a twist strip (6) at the R angle between the long string prepreg (2-2) and the skin prepreg (1-1); S5, laying a pressure pad (7) on the surface of the pre-compacted first mold (3-1) and the long stringer preform (10); S6, laying a vacuum auxiliary material (8) on the outside of the pressure pad (7) to make a bag, then curing and demoulding, to obtain a composite material U-shaped long stringer reinforced wall panel blank; S7. Machining the composite material U-shaped long stringer reinforced wall panel blank to form a beveled end (2-1) at the end of the long stringer (2) to obtain a composite material U-shaped long stringer reinforced wall panel.

2. A composite material U-shaped long stringer reinforced wall panel co-curing molding process according to claim 1, characterized in that: The skin prepreg (1-1) and the stringer prepreg (2-2) are selected from one of carbon fiber prepreg, glass fiber prepreg and Kevlar prepreg.

3. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The first mold (3-1) is made of a metal material; the second mold (3-2) is made of a wood material.

4. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The pre-compacting temperature in step S2 is 60-80° C., and the pre-compacting pressure is 0.1-0.3 MPa.

5. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The skin laying mould (4) is provided with a laser projection positioning target for positioning when laying the skin prepreg.

6. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The skin laying mold (4) is provided with a positioning pin for fixing the first mold (3-1).

7. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The vacuum auxiliary materials described in step S6 include a release cloth, an isolation film, a breathable felt and a vacuum bag.

8. The co-curing molding process of a composite material U-shaped long stringer reinforced wall panel according to claim 1, characterized in that: The curing temperature in step S6 is 120-140° C., and the curing pressure is 0.2-0.7 MPa.

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