Composite beam forming die and integral forming method thereof

Abstract

This invention provides a composite material beam molding die and its integral molding preparation method, comprising an upper plate, a bottom plate, an inner segment group, an inner mold, and an outer mold; the inner mold is fixed between the upper plate and the bottom plate, and gaps for molding composite material beams are left between the inner molds, between the inner mold and the inner segment group, and between the inner mold and the outer mold; the outer mold is fixed on the outside of the inner mold and is fixedly connected to the upper plate and the bottom plate; the inner segment group is fixed on the inside of the inner mold and is fixedly connected to the bottom plate. This invention can meet the co-curing molding of irregular beams composed of webs, side flanges, and box-like structures, and the prepared composite material beams have high dimensional accuracy, glossy inner and outer surfaces, high internal quality, and low mold manufacturing cost.

Description

Technical Field

[0001] This invention relates to the technical field, and in particular to a composite material beam molding die and its integral molding preparation method. Background Technology

[0002] Fiber-reinforced thermosetting resins are widely used in cutting-edge technology fields such as aviation and aerospace due to their excellent mechanical properties such as high specific strength and high specific modulus. In recent years, the requirements for lightweighting of aviation and aerospace structural components have become increasingly stringent, and carbon fiber composite materials have gradually replaced metal materials as the main load-bearing structural materials for spacecraft.

[0003] Composite beams and frames play a crucial role in weight reduction, load-bearing capacity, and dimensional stability of projectile and space structures. Currently, composite beams are typically manufactured using the following processes:

[0004] (1) Autoclave and layup process. Due to the characteristic of uniform pressurization of products by the autoclave process, this process has limitations in preparing complex cross-section and variable thickness beam structures, making it difficult to guarantee dimensional accuracy and resulting in high mold manufacturing costs.

[0005] (2) RTM process. This process requires high resin flowability and low fiber volume content. The resulting composite material is prone to internal quality defects and is not suitable for the preparation of high-performance carbon fiber composite materials.

[0006] (3) Secondary assembly process. This process requires drilling holes on the surface of the already prepared web and flange composite materials, which will reduce the performance of the composite materials and require a large amount of assembly work for complex composite beams.

[0007] (4) Press molding process. Due to the limitations of the press's pressure direction and sequence, this process is only suitable for manufacturing simple composite material beams. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a composite material beam molding die and its integrated molding preparation method, which can meet the requirements of co-curing compression molding of irregular beams composed of web, two side flanges and box structure. Moreover, the prepared composite material beam has high dimensional accuracy, glossy inner and outer surfaces, high internal quality, and low mold manufacturing cost.

[0009] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0010] The present invention provides a composite material beam forming mold, comprising an upper plate, a bottom plate, an inner segment group, an inner mold, and an outer mold; the inner mold is fixed between the upper plate and the bottom plate, and gaps for forming composite material beams are left between the inner molds, between the inner mold and the inner segment group, and between the inner mold and the outer mold; the outer mold is fixed on the outside of the inner mold and is fixedly connected to the upper plate and the bottom plate; the inner segment group is fixed on the inside of the inner mold and is fixedly connected to the bottom plate.

[0011] Preferably, the upper plate, the bottom plate, and the inner mold are connected by screws and positioned by locating pins.

[0012] Preferably, a bottom plate stop is also provided on the bottom plate for positioning the inner petal group.

[0013] Preferably, the inner segments are fixed at an angle of 10° to each other. By applying pressure to the middle part of the inner segment group, the surrounding inner segments are squeezed outward, thus pressurizing the prepreg.

[0014] Preferably, the inner mold and inner segments are made of aluminum alloy, while the upper plate, bottom plate and outer mold are made of 45 steel or Q235 steel.

[0015] Preferably, pressure threaded holes for applying pressure are provided on the upper plate and the bottom plate.

[0016] Preferably, bolt through holes for connecting the inner mold are provided on the upper plate and the bottom plate; and bolt through holes for connecting the inner segment group to the bottom plate are provided on the inner segment group.

[0017] The present invention provides a composite material beam, which includes an outer flange, an inner flange, a web and vertical stiffeners. The two ends of the vertical stiffeners are respectively vertically connected to the inner flange and the outer flange. The web and the vertical stiffeners are vertically fixed, and the composite material beam is divided into upper and lower layers with the web as the center line.

[0018] The present invention provides an integral molding preparation method for composite material beams, comprising the following steps:

[0019] S1. Prepare composite prepreg and control the fiber volume content of the composite prepreg to be between 54% and 60%;

[0020] S2. Preheat the molding die. After preheating, lay the composite prepreg on the inner mold. The layup thickness of the composite prepreg is 1 mm.

[0021] S3. After laying, make a vacuum bag, extract the vacuum, and compact the composite prepreg.

[0022] S4. Assemble the laid inner mold with the upper plate and the bottom plate, and lay composite prepreg on the assembled upper plate and bottom plate. The layup thickness of the composite prepreg is 0.5 mm.

[0023] S5. After laying, assemble the top plate and bottom plate and apply pressure;

[0024] S6. After pressurization, lay composite prepreg on the outer and inner wing plates. The layup thickness of the composite prepreg is 1.5 mm.

[0025] S7. After laying out, assemble the outer mold and inner segment groups, and close the mold as a whole;

[0026] S8. Preheat the molding die and the composite prepreg, and then heat seal the die. The preheating time and temperature is 90℃ / 2h.

[0027] S9. After heat sealing, place the molding mold into a curing oven for integrated molding and co-curing. Set the curing regime to 120℃ / 2h~150℃ / 2h~190℃ / 2h.

[0028] S10, demolding, to obtain composite material beam.

[0029] Preferably, the reinforcement of the composite prepreg is T700 and / or T800 grade carbon fiber, and the matrix material of the composite prepreg is cyanate resin, bismaleimide resin, or epoxy resin.

[0030] The present invention can achieve the following technical effects:

[0031] 1. The overall structure of the molding die is simple, which can meet the co-curing molding of irregular beams composed of web, side flanges and box structure.

[0032] 2. Products manufactured using the one-piece molding method are free from internal and external quality defects, and have high dimensional accuracy of the ribs and inner and outer contours; the inner contour is free from quality problems such as bridging, voids, and diffuse defects, making it suitable for manufacturing small batches of complex structural beams.

[0033] 3. The one-piece molding process can significantly shorten the production cycle while ensuring product quality.

[0034] 4. The molding die has a simple structure and low manufacturing cost; it avoids the high mold costs or material performance damage caused by secondary assembly processes when manufacturing complex frame and beam structures using autoclave processes. Attached Figure Description

[0035] Figure 1 This is a cross-sectional view of a composite beam forming mold provided according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the inner lobe structure provided according to an embodiment of the present invention.

[0037] Figure 3 This is an assembly diagram of the inner mold and the upper plate provided according to an embodiment of the present invention.

[0038] Figure 4 This is an assembly diagram of the inner mold and the base plate provided according to an embodiment of the present invention.

[0039] Figure 5 This is an assembly diagram of the base plate and the top plate provided according to an embodiment of the present invention.

[0040] Figure 6 This is an isometric view of a composite material beam provided according to an embodiment of the present invention.

[0041] Figure 7 This is a cross-sectional view of a composite material beam provided according to an embodiment of the present invention.

[0042] Figure 8 This is a flowchart of a method for integrally molding a composite beam according to an embodiment of the present invention.

[0043] Figure 9 This is a schematic diagram of a composite beam layup provided according to an embodiment of the present invention.

[0044] The reference numerals in the attached drawings include: upper plate 1, bottom plate 2, bottom plate stop 21, inner segment group 3, inner segment 31, inner mold 4, outer mold 5, pressure threaded hole 6, bolt through hole 7, inner segment bolt through hole 8, composite material beam 9, outer wing plate 91, inner wing plate 92, web plate 93, and vertical rib 94. Detailed Implementation

[0045] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0047] The embodiments of the present invention include three parts: a composite material beam molding die, a composite material beam, and a method for integrally molding and preparing a composite material beam.

[0048] The first part is the composite material beam molding die:

[0049] Figure 1 The cross-sectional structure of the composite beam forming mold provided in an embodiment of the present invention is shown.

[0050] like Figure 1As shown, the composite material beam forming mold provided in this embodiment of the invention includes an upper plate 1, a bottom plate 2, an inner segment group 3, an inner mold 4, and an outer mold 5; the inner mold 4 is fixed between the upper plate 1 and the bottom plate 2, and a gap is left between the inner molds 4 for forming the composite material beam 9; the outer mold 5 is fixed on the outside of the inner mold 4 and is fixedly connected to the upper plate 1 and the bottom plate 2; the inner segment group 3 is fixed on the inside of the inner mold 4 and is fixedly connected to the bottom plate 2.

[0051] A base plate stop 21 is also provided on the base plate 2 for positioning the inner segment group 3.

[0052] The outer mold 5 is made of 45# steel or Q235 steel. Utilizing the difference in thermal expansion coefficients between aluminum alloy and steel, the prepreg can be further pressurized during the curing process.

[0053] Figure 2 The internal lobe structure provided in an embodiment of the present invention is shown.

[0054] like Figure 2 As shown, the number of inner lobes 31 in the inner lobes group 3 is at least two. In the embodiment provided by the present invention, the inner lobes 31 are fixed at an angle of 10° to each other, and the inner lobes group 3 is triangular. The inner lobes group 3 is provided with inner lobes bolt through holes 8 for connecting the base plate 2.

[0055] For composite material products that require pressure from the inside out and have limited space, it is difficult to use a vertical pressure method. Therefore, the inner pressure mold is set as an inner segment group 3, with a certain angle between each segment. The number of inner segments 31 in the inner segment group 3 and the angle between the inner segments 31 can be adjusted according to the actual pressure requirements. Theoretically, the angle should be greater than 0 degrees. However, in actual operation, in order to comprehensively consider the force transmission and the space where the inner segments 31 can be placed, the angle is usually set to 10 degrees to meet the requirements.

[0056] With the design of the inner segment group 3 mold described above, during the mold closing process, the inner segment 31 in the center can be pressed downward, indirectly squeezing the inner segment 31 around the perimeter outward, thereby pressurizing the prepreg.

[0057] The preferred number of inner segment groups 3 provided in this embodiment of the invention is five inner segments 31. The five inner segments 31 are assembled sequentially at a fixed angle and demolded at a demolding angle of 10°. The outer dimensions of the assembled inner segment group 3 are consistent with the inner cavity dimensions of the inner mold 4. Furthermore, installing the inner segment group 3 can apply pressure to the inner wing plate 92 of the composite material beam 9, thereby improving the accuracy of the internal dimensions.

[0058] The inner mold 4 and the inner segment 31 are preferably made of aluminum alloy, because the coefficient of thermal expansion of aluminum alloy is much greater than that of steel. During the product curing process, the size of the cavity is reduced, which is conducive to pressurizing the upright rib 94.

[0059] Figure 3 An assembly diagram of the inner mold and the upper plate provided in an embodiment of the present invention is shown.

[0060] Figure 4 An assembly diagram of the inner mold and base plate provided in an embodiment of the present invention is shown.

[0061] like Figures 3-4 As shown, the upper plate 1, the bottom plate 2, and the inner mold 4 are connected by screws, and are positioned by locating pins after connection.

[0062] The materials for the upper plate 1 and the bottom plate 2 are 45 steel or Q235 steel.

[0063] Figure 5 This is an assembly diagram of the base plate and the top plate provided according to an embodiment of the present invention.

[0064] like Figure 5 As shown, the upper plate 1 and the bottom plate 2 are provided with a pressurizing threaded hole 6 for pressurizing and a bolt through hole 7 for connecting the inner mold 4.

[0065] The second part consists of composite material beams:

[0066] Figure 6 This is an isometric view of a composite material beam provided according to an embodiment of the present invention.

[0067] like Figure 6 As shown, the composite beam 9 includes an outer flange 91, an inner flange 92, a web 93, and a vertical rib 94. The two ends of the vertical rib 94 are vertically connected to the inner flange 92 and the outer flange 91, respectively, and the web 93 is vertically fixed to the vertical rib 94.

[0068] Figure 7 This is a cross-sectional view of a composite material beam provided according to an embodiment of the present invention.

[0069] like Figure 7 As shown, since the web 93 is fixed vertically to the vertical reinforcement 94, the composite beam 9 is divided into upper and lower layers with the web 93 as the center line.

[0070] Part Three describes the integral molding method for composite beams:

[0071] Figure 8 This is a flowchart of a method for integrally molding a composite beam according to an embodiment of the present invention.

[0072] like Figure 8 As shown in the figure, this invention also provides a method for integral molding of composite beam molds, comprising the following steps:

[0073] S1. Prepare composite prepreg and control the fiber volume content of the composite prepreg to be between 54% and 60%;

[0074] The reinforcement of the composite prepreg is T700 and / or T800 grade carbon fiber, and the matrix material of the composite prepreg is cyanate resin, bismaleimide resin, or epoxy resin.

[0075] S2. Preheat the molding die. After preheating, lay the composite prepreg on the inner mold 4. The layup thickness of the composite prepreg is 1 mm.

[0076] The composite prepreg is laid in a U-shape on the surface of composite beam 9.

[0077] S3. After laying, make a vacuum bag, vacuum it, and compact the composite prepreg.

[0078] S4. Assemble the laid inner mold 4 with the upper plate 1 and the bottom plate 2, and lay composite prepreg on the assembled upper plate 1 and bottom plate 2. The layup thickness of the composite prepreg is 0.5 mm.

[0079] S5. After laying, assemble the upper plate 1 and the bottom plate 2 and apply pressure;

[0080] S6. After pressurization, lay composite prepreg on the outer wing plate 91 and the inner wing plate 92. The layup thickness of the composite prepreg is 1.5 mm.

[0081] Figure 9 A schematic diagram of the composite beam layup provided in an embodiment of the present invention is shown.

[0082] like Figure 9 As shown, the composite beam 9 has the following ply structure: first, a U-shaped ply with a thickness of 1 mm; second, an overall ply with a thickness of 0.5 mm; and third, a ply for both side flanges with a thickness of 1.5 mm.

[0083] S7. After laying out, assemble the outer mold 5 and the inner segment group 3, and close the mold as a whole.

[0084] S8. Preheat the molding die and the composite prepreg, and then heat seal the die. The preheating time and temperature is 90℃ / 2h.

[0085] S9. After heat sealing, place the molding mold into a curing oven for integrated molding and co-curing. Set the curing regime to 120℃ / 2h~150℃ / 2h~190℃ / 2h.

[0086] S10, demolding, to obtain composite beam 9.

[0087] The dimensions of the composite beam 9 in this embodiment of the invention are as follows: the thickness of the vertical rib 94 is 2mm, the thickness of the outer flange 91 is 3mm, the thickness of the inner flange 92 is 3mm, and the thickness of the web 93 is 3mm.

[0088] The composite beam 9 has an H-shaped cross-section, making it a symmetrical structure relative to the H-section with respect to the mid-surface of the web 93. Both the inner and outer contours of the composite beam 9 are triangular. The outer contour dimensions are 650×750×100 mm, and the inner contour dimensions are 350×420×100 mm.

[0089] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0090] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0091] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A composite beam forming mold characterized by, The system includes an upper plate (1), a bottom plate (2), an inner segment group (3), an inner mold (4), and an outer mold (5). The inner mold (4) is fixed between the upper plate (1) and the bottom plate (2). Gaps for forming composite material beams (9) are left between the inner molds (4), between the inner molds (4) and the inner segment group (3), and between the inner molds (4) and the outer mold (5). The outer mold (5) is fixed to the outside of the inner mold (4) and is fixed to the upper plate (1) and the bottom plate (2). The inner segment group (3) is fixed to the inner side of the inner mold (4) and fixedly connected to the bottom plate (2); the number of inner segments (31) in the inner segment group (3) is at least two, the angle between the inner segments (31) is 10°, and the inner segment group (3) is triangular; the material of the inner mold (4) and the inner segments (31) is aluminum alloy, and the material of the upper plate (1), the bottom plate (2) and the outer mold (5) is 45 steel or Q235 steel.

2. The composite beam forming mold of claim 1, wherein, The upper plate (1), the bottom plate (2), and the inner mold (4) are connected by screws and positioned by locating pins.

3. The composite beam forming mold of claim 1, wherein, A bottom plate stop (21) for positioning the inner segment group (3) is also provided on the bottom plate (2).

4. The composite beam forming mold of claim 1, wherein, Pressurizing threaded holes (6) for pressurizing are provided on the upper plate (1) and the bottom plate (2).

5. The composite beam forming mold of claim 1, wherein, Bolt through holes (7) for connecting the inner mold (4) are provided on the upper plate (1) and the bottom plate (2); and inner segment bolt through holes (8) for connecting the bottom plate (2) are provided on the inner segment group (3).

6. A method of integrally forming a composite beam, using the composite beam forming mold according to claim 1, characterized by, Includes the following steps: S1. Prepare composite material prepreg, and control the fiber volume content of the composite material prepreg to be between 54% and 60%; S2. Preheat the molding die, and after preheating, lay the composite prepreg on the inner mold (4). The layup thickness of the composite prepreg is 1 mm. S3. After laying, make a vacuum belt, extract the vacuum, and compact the composite prepreg. S4. Assemble the inner mold (4) after it has been laid out with the upper plate (1) and the bottom plate (2), and lay the composite prepreg on the assembled upper plate (1) and the bottom plate (2). The layup thickness of the composite prepreg is 0.5 mm. S5. After laying, pressurize the upper plate (1) and the bottom plate (2) during assembly. S6. After pressurization, the composite material prepreg is laid on the outer wing plate (91) and the inner wing plate (92), and the layup thickness of the composite material prepreg is 1.5 mm. S7. After laying out, assemble the outer mold (5) and the inner segment group (3) and close the mold as a whole; S8. Preheat the molding die and the composite prepreg, and heat seal the mold. The preheating time and temperature is 90℃ / 2h. S9. After heat sealing, the molding mold is placed in a curing oven for integral molding and co-curing. The curing regime is set to 120℃ / 2h~150℃ / 2h~190℃ / 2h. S10, Demolding, to obtain the composite material beam (9).

7. The method of one piece fabrication of a composite beam according to claim 6, wherein, The reinforcing body of the composite prepreg is T700-grade and / or T800-grade carbon fiber, and the matrix material of the composite prepreg is cyanate resin or bismaleimide resin or epoxy resin.

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