Molding die and molding method for composite material member having a gradually changing cross-sectional characteristic

Abstract

The application discloses a forming die and forming method of a composite material component with a gradually-changing cross-section feature, and belongs to the technical field of composite material component manufacturing. The forming die mainly comprises an upper die, a bottom die, a core block and a middle frame edge strip, wherein the core block comprises a central core block and a plurality of occupying core blocks, and the middle frame edge strip comprises four independent edge strips. When the pre-impregnated material is laid in the forming die, the occupying core blocks are used for occupying, the middle frame edge strip is used for fastening, and pre-compaction operation is performed in combination with a pre-compaction tool and an occupying tool, so that the composite material component with the gradually-changing cross-section feature can be formed. The application can reduce the product extrusion caused by the cooling shrinkage of the mold steel material caused by the thermal expansion factor, the resin enrichment caused by the mold extrusion fluctuation of the thin-thick feature structure area, improve the heat transfer efficiency, control the resin viscosity, and effectively improve the product forming quality.

Description

Molding molds and molding methods for composite material components with gradient cross-section features Technical Field

[0001] This invention relates to a molding die and molding method for composite material components with a gradient cross-section, belonging to the field of composite material component manufacturing technology. Background Technology

[0002] Carbon fiber reinforced bismaleimide resin matrix composites possess characteristics such as high temperature resistance and excellent mechanical properties, and are mainly used in a series of temperature-resistant load-bearing structural components. The commonly used manufacturing process is compression molding. The component to be molded in this invention is made using carbon fiber reinforced bismaleimide resin matrix composites. The structure of this component is shown in Figures 1A-1C, where Figure 1A is a bottom view, Figure 1B is a top view, and Figure 1C is a half-side cross-sectional view. The component is generally annular, containing a central annular groove structure 01. The outer side of the groove structure 01 is an annular skin 02, and the skin 02 is provided with reinforcing ribs 03. Specifically, the reinforcing ribs 03 include the outermost annular rib 03a and four strip ribs 03b connecting the groove structure 01 and the annular rib 03a. The cross-section of the groove structure 01 is a gradient region cross-section (see Figure 1C). Its inner side is the groove 01a, below the groove 01a is a bottom step 01b, and the outer side is a slope 01c. The slope 01c smoothly transitions to the skin 02 for sealing the heat insulation ring. In addition, multiple mounting holes 04 are machined on the annular rib 03a for installation of the final assembly docking compartment, etc.

[0003] Currently, in the process of manufacturing this component using traditional molds, the curing temperature of bismaleimide resin is above 200℃. The mold steel expands due to heat, making the component susceptible to physical defects such as cracks and bending misalignment caused by mold compression. Furthermore, the large height difference in the groove structure leads to material extrusion during mold closing, resulting in localized resin accumulation and poor component processability. In addition, the viscosity of the resin in the mold cavity is affected by heat transfer efficiency and uniformity, with the heat transfer rate primarily determined by mold design. If the viscosity is low, a large amount of resin is lost during the pressurization stage, resulting in delamination and porosity within the component, macroscopically reflecting a rough appearance, widespread pitting and pores, and a weight lower than the theoretical weight. If the viscosity is high, the resin layer undergoes extensive cross-linking, resulting in a thick surface adhesive layer. This leads to a certain mold closing gap during the pressurization stage, with the component's skin and reinforcing ribs being larger than the theoretical thickness, and the actual weight being heavier than the theoretical weight, failing to meet the weight reduction requirements of composite components. Therefore, there is an urgent need to develop a new molding die and molding method to produce ideal components. Summary of the Invention

[0004] The purpose of this invention is to provide a molding die and molding method that can mold composite material components with gradient cross-sectional features that meet the requirements. It has the advantages of facilitating component molding and demolding operations, reducing the compression of components caused by the thermal expansion of the mold steel due to cooling and shrinkage, avoiding resin enrichment caused by the fluctuation of material extrusion during mold closing in the gradient area, improving heat transfer efficiency, component molding quality, and raw material utilization.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A molding die for a composite material component with a gradient cross-section, comprising:

[0007] The upper mold 10 has a bottom surface including an annular upper forming surface 13;

[0008] The bottom mold 20 has a top surface comprising a concentric circular groove 21, an annular cavity 22, an annular lower forming surface 23, an annular movable area 24, and an annular edge 25 from the inside out. The outer edge of the annular cavity 22 includes an inclined forming surface 22a, and the annular lower forming surface 23 includes an annular rib forming groove 23a and four radial strip rib forming grooves 23b located on the outer edge.

[0009] The core block 30 includes a central core block 31 and several occupant core blocks 32; one of the occupant core blocks 32 is a reverse slope core block 32b, and the rest are positive slope core blocks 32a; all the occupant core blocks 32 are assembled around the central core block 31 to form a disk shape, and the side of all the occupant core blocks 32 includes a boss 32c; during mold assembly, the lower end of the central core block 31 is placed in the circular groove 21 of the bottom mold 20, and the occupant core blocks 32 are placed in the annular cavity 22 of the bottom mold 20;

[0010] The middle frame edge strip 40 includes four independent edge strips, which form a ring when assembled. During mold assembly, it is placed in the annular movable area 24 of the bottom mold 20. Each edge strip is provided with at least one glue flow groove 41.

[0011] Furthermore, the upper mold 10 also includes a circular positioning hole 11 located at the center, which is used to limit the upper end of the central core block 31.

[0012] Furthermore, the bottom surface of the upper mold 10 also includes an annular positioning groove 12 for limiting the positioning core block 32.

[0013] Furthermore, the diameters of the upper and lower ends of the central core block 31 are smaller than those of the middle part, and the side of the middle part is a slope, with the upper end of the slope tilting outward.

[0014] Furthermore, the center core block 31 is provided with a screw hole 31a at its center, and screws are used to fix it to the bottom mold 20 through the screw hole 31a.

[0015] Furthermore, the outer surface of the occupier 32 includes a slope, which is the surface between the upper edge and the boss 32c, with the upper edge sloping inward.

[0016] Furthermore, each of the side strips of the middle frame 40 includes two glue-flowing grooves 41 located on the top surface.

[0017] Furthermore, each of the side strips of the middle frame 40 includes a limiting groove 42 located on the bottom surface.

[0018] Furthermore, the annular movable area 24 of the bottom mold 20 includes four radial limiting blocks 24a, which cooperate with the limiting groove 42 to circumferentially limit the middle frame edge strip 40.

[0019] Furthermore, each side of the middle frame edge strip 40 includes a set screw groove 43.

[0020] Furthermore, the bottom mold 20 has several set screw holes evenly distributed around its edge, and set screws 25a are screwed in thereon. The end of the set screw 25a engages with the set screw groove 43.

[0021] A molding method for a composite material component with a gradient cross-section, comprising molding the component using the aforementioned molding die, including the following steps:

[0022] A layer of carbon cloth prepreg is laid on the entire molding area of ​​the bottom mold 20 for the base layer. The entire molding area includes the area where the inclined molding surface 22a, the annular lower molding surface 23, the annular rib molding groove 23a and the strip rib molding groove 23b are located.

[0023] A prepreg layer is laid at the bottom side step of the groove at the position of the inclined forming surface 22a;

[0024] In the annular cavity 22 of the bottom mold 20, the positive slope core block 32a of the occupant core block 32 is placed in sequence, and the reverse slope core block 32b is installed last to occupy the cavity; after the occupant core block 32 is placed, the center core block 31 is placed.

[0025] Prepreg layup is performed in the gradient region of the component at position 22a of the inclined forming surface;

[0026] Prepreg layering is performed in the annular rib forming groove 23a and the strip rib forming groove 23b;

[0027] Skin lay-up is performed at point 23 on the lower ring-shaped surface;

[0028] A full layer of carbon fiber prepreg is laid on the top surface of the component;

[0029] After all layers are laid up, the mold is closed and cured according to a predetermined procedure to obtain a composite material component with a gradient cross-section.

[0030] Furthermore, during and after the carbon fiber prepreg layer is laid in the gradient area of ​​the component, two pre-compaction processes are performed, including:

[0031] Heat the first pre-compression fixture 51 and the third pre-compression fixture 53;

[0032] When half of the inclined forming surface 22a is laid, the first pre-compression operation is carried out: the release film is laid, the corner structure 51a of the first pre-compression tool 51 is used to cooperate with the inclined forming surface 22a, and the second pre-compression tool 52 is pressed on the first pre-compression tool 51 to cooperate and compact.

[0033] Remove the first pre-compression fixture 51, the second pre-compression fixture 52, and the release film, and continue to lay the remaining layers. After completion, perform a second pre-compression operation: lay the release film and place the first occupant fixture 54 and the second occupant fixture 55. The first occupant fixture 54 is placed outside the occupant core block 32 and cooperates with and fixes the occupant core block 32. The second occupant fixture 55 is placed in the annular lower forming surface 23 area of ​​the bottom mold 20, and its outer side cooperates with the middle frame edge strip 40. Finally, place the third pre-compression fixture 53 between the first occupant fixture 54 and the second occupant fixture 55 for pre-compression.

[0034] The beneficial effects of this invention are:

[0035] 1. Addressing defects caused by thermal expansion: Optimized mold structure helps resolve crack defects caused by the shrinkage of steel due to thermal expansion, which leads to component compression. Reasonable mold size design and improved heat transfer efficiency help adjust and optimize the component forming process, thereby improving component quality.

[0036] 2. Reduce the degree of compression in thin and thick structural areas: The addition of pre-compression and positioning tooling effectively reduces the degree of prepreg compression in thin and thick structural areas, reduces the risk of resin enrichment, and helps to improve the quality of components.

[0037] 3. Optimize the utilization rate of prepreg: In view of the gradual characteristics of the annular component and the groove structure with large thickness, a segmented layering method is adopted, with alternating staggered breaks, to save material usage and improve the utilization rate of the prepreg main material.

[0038] 4. Easy to operate and reduces demolding difficulty: The modular design of the mold makes operation more convenient, reduces the difficulty of demolding components, and simplifies the production process.

[0039] This invention effectively solves the extrusion delamination defects that may occur during component production by optimizing the mold structure and adjusting the molding process, thereby improving the quality of the components, reducing production costs, and increasing the utilization rate of prepreg. Attached Figure Description

[0040] Figures 1A-1C show the bottom view, top view, and cross-sectional view of the component.

[0041] Figure 2 is a structural diagram of the molding die in the embodiment.

[0042] Figures 3A-3B show the top and bottom views of the upper mold.

[0043] Figure 4 is a top view of the bottom mold.

[0044] Figures 5A-5D show the three-dimensional view, side view, top view, and exploded view of the core.

[0045] Figure 6 is a structural diagram of the core block assembled on the bottom mold.

[0046] Figures 7A and 7B show the assembly and exploded views of the middle frame side strip.

[0047] Figures 8A-8B show the top and bottom views of a single edge strip.

[0048] Figures 9A-9B are structural diagrams of the first pre-compression fixture.

[0049] Figure 10 is a structural diagram of the second pre-compression fixture.

[0050] Figures 11A-11B show the positional relationship between the third pre-compression fixture and the two stationary fixtures.

[0051] Figures 12A-12B are schematic diagrams of two pre-compaction processes.

[0052] Figure 13 is a schematic diagram of the component forming process in the embodiment.

[0053] Figure 14 is a schematic diagram of the prepreg used for layup of molded components.

[0054] Explanation of reference numerals in the attached figures:

[0055] 01: Groove structure;

[0056] 01a: Groove;

[0057] 01b: Bottom side step;

[0058] 01c: Bevel;

[0059] 02: Skin;

[0060] 03: Reinforcing ribs;

[0061] 03a: Circular reinforcement;

[0062] 03b: Strip reinforcement;

[0063] 04: Mounting holes;

[0064] 10: Upper mold;

[0065] 11: Circular positioning hole;

[0066] 12: Annular positioning groove;

[0067] 13: Ring-shaped upper forming surface;

[0068] 14: Upper mold edge;

[0069] 20: Bottom mold;

[0070] 21: Circular groove;

[0071] 22: Annular cavity;

[0072] 22a: Inclined forming surface;

[0073] 23: Annular lower forming surface;

[0074] 23a: Annular rib forming groove;

[0075] 23b: Strip rib forming groove;

[0076] 24: Circular activity area;

[0077] 24a: Limit block;

[0078] 25: Circular edge;

[0079] 25a: Set screw;

[0080] 25b: Temperature measuring port;

[0081] 30: Chip;

[0082] 31: Central core block;

[0083] 31a: Screw hole;

[0084] 32: Placeholder chip;

[0085] 32a: Positive tilt core block;

[0086] 32b: Reverse slope core

[0087] 32c: Boss;

[0088] 40: Middle frame border;

[0089] 41: Glue delivery tank;

[0090] 42: Limiting groove;

[0091] 43: Set screw groove;

[0092] 51: First pre-compression fixture;

[0093] 51a: Corner structure;

[0094] 52: Second pre-compression fixture;

[0095] 53: Third pre-compression fixture;

[0096] 54: First positioning fixture;

[0097] 55: Second positioning fixture;

[0098] 55a: Thick torus;

[0099] 55b: Thin torus. Detailed Implementation

[0100] To make the technical features, advantages, and effects of the present invention more apparent and understandable, embodiments are listed below and described in detail with reference to the accompanying drawings.

[0101] I. Molding mold

[0102] This embodiment specifically discloses a molding die for a composite material component with a gradient cross-section. It adopts an upper and lower mold structure, with the mold separation surface on the outer surface of the component. Its main components include an upper mold 10, a bottom mold 20, a core block 30, and a middle frame strip 40. The core block 30 and the middle frame strip 40 are located inside the upper mold 10 and the bottom mold 20 when the mold is closed. When the mold is closed, all the structures together form the outer contour cavity of the component for component molding.

[0103] The structure of the upper mold 10 is shown in Figures 3A and 3B, where Figure 3A is a top view and Figure 3B is a bottom view. The upper mold 10 is circular, with a circular positioning hole 11 at its center for positioning the central core block 31 during mold closing. An annular positioning groove 12 surrounding the circular positioning hole 11 is provided on the bottom surface of the upper mold 10 for positioning the occupant core block 32. An annular upper forming surface 13 surrounds the outer side of the annular positioning groove 12 for forming the top surface of the skin of the component. The outer side of the annular upper forming surface 13 is the edge 14 of the upper mold. The depth gradually decreases from the annular positioning groove 12 to the annular upper forming surface 13, and then to the edge.

[0104] The structure of the bottom mold 20 is shown in Figure 4. The center of the top surface of the bottom mold 20 is a circular groove 21 for placing the central core block 31. Around the circular groove 21 is an annular cavity 22 for placing the occupant core block 32. The periphery of the annular cavity 22 is a sloping forming surface 22a, used to form the sloping surface of the groove structure of the component. Around the annular cavity 22 is an annular lower forming surface 23, used to form the skin bottom surface of the component. The heights of the circular groove 21, the annular cavity 22, and the annular lower forming surface 23 increase sequentially. The annular lower forming surface 23 is provided with an annular rib forming groove 23a surrounding the edge and four strip rib forming grooves 23b facing the center. Outside the annular lower forming surface 23 is a surrounding annular movable area 24, used to place the middle frame strip 40. The width of the annular movable area 24 is large enough to increase the stroke of the middle frame strip 40, allowing it to move radially along its width when needed. This ensures that the middle frame strip 40, after being divided into four segments, can be effectively controlled to move along the inner and outer axes. The annular movable area 24 contains four strip-shaped limiting blocks 24a, which engage with the limiting grooves 42 on the middle frame strip 40 to prevent the middle frame strip 40 from rotating around the annular movable area 24, but do not limit radial movement. The outer side of the annular movable area 24, i.e., the edge of the bottom mold 20, is an upwardly protruding annular edge 25. Eight ejector screw holes are evenly distributed circumferentially on this annular edge 25, with ejector screws 25a screwed into them. The ejector screws 25a engage with the ejector screw grooves 43 on the side of the middle frame strip 40 for material closing. A temperature measuring hole 25b is also provided on the side of the annular edge 25, which extends to the circular groove 21 of the bottom mold 20, and can accurately measure the curing temperature of the component. The overall thickness of the bottom mold 20 is lower than that of the bottom mold 20 of traditional molds, which can effectively improve the heat transfer efficiency while ensuring strength.

[0105] The structure of core block 30 is shown in Figures 5A-5D, where Figure 5A is a perspective view, Figure 5B is a side view, Figure 5C is a top view, and Figure 5D is an exploded view. Core block 30 includes a central core block 31 and seven spacer core blocks 32 surrounding the central core block 31. The central core block 31 is circular, and the seven spacer core blocks 32, when assembled, form a ring around the central core block 31. The outer surface of the spacer core blocks 32 is a slightly inclined slope, with the top of the slope slightly inward and the connecting boss 32c slightly outward, as shown in Figure 5B. The diameters of the upper and lower ends of the central core block 31 are smaller than the diameter of the middle part. The lower end is used to confine it within the circular groove 21 of the bottom mold 20, and the upper end is used to confine it within the circular positioning hole 11 of the upper mold 10 when the mold is closed. The contour surface of the middle part has a certain slope, as shown by the dotted line in Figure 5B. This ensures that after the central core block 31 is fixed, the interference of the slope will fix the occupant core block 32 to the bottom mold 20, thus eliminating the need for screw fixing of the occupant core block 32 and facilitating demolding operations. The seven occupant core blocks 32 are all arc-shaped and vary in size. Specifically, they include six positive slope core blocks 32a, with an outer edge length greater than the inner edge length, and one negative slope core block 32b, with an outer edge length less than the inner edge length, as shown in Figures 5C and 5D. Each occupant core block 32 has a boss 32c on its side. After assembly, the bosses 32c form a ring for forming the groove of the component. In practical use, the seven spacer core blocks 32 are assembled with the central core block 31, forming a disc shape. They are placed within the circular area formed by the circular groove 21 and the annular cavity 22 at the center of the bottom mold 20, as shown in Figure 6. This spacer occupies the cavity to form the groove structure of the component. The bottom of the central core block 31 is confined within the circular groove 21, and it is installed vertically during placement. The spacer core blocks 32 are located within the annular cavity 22. The central core block 31 is secured to the bottom mold 20 using fastening screws and top screw holes 31a to ensure the component layup process. Specifically, when placing the core blocks, the placeholder core blocks 32 are placed first, followed by the center core block 31. When placing the placeholder core blocks 32, the forward-sloping core blocks 32a are placed sequentially in the annular cavity 22 of the bottom mold 20. After placing the forward-sloping core blocks 32a, the reverse-sloping core blocks 32b are placed in the empty space. Specifically, the reverse-sloping core blocks 32b are inserted from the inside to the outside of the empty space in the middle (the empty space formed because the center core block 31 has not yet been placed). After all the placeholder core blocks 32 are placed, the center core block 31 is placed from top to bottom, and the side slope of the center core block 31 is used to press against the surrounding placeholder core blocks 32.

[0106] The structure of the middle frame edge strip 40 is shown in Figures 7A-7B. It is a circular structure composed of four independent edge strips, which can be fastened and released, and has a movable stroke. The structure of each edge strip is shown in Figures 8A-8B. Its top surface has two flow grooves 41 to ensure that excess resin can flow out smoothly during molding. The bottom surface has a limiting groove 42, which is used to cooperate with the limiting block 24a on the bottom mold 20 to limit the circumferential movement of the strip, but does not hinder the radial movement of the edge strip. The side of the edge strip has two ejector screw grooves 43. The end of the ejector screw 25a on the bottom mold 20 abuts against the ejector screw groove 43 to control the tightness of the middle frame edge strip 40, which is used for the closing of the middle side edge strip after material filling.

[0107] II. Pre-compaction fixtures

[0108] During component molding, pre-compaction fixtures are used to improve the molding result. This invention mainly focuses on the design of pre-compaction fixtures for the sloped surface of the gradient area of ​​the groove structure of the component. Specifically, three types of pre-compaction fixtures and two auxiliary positioning fixtures are designed, with a circular or near-circular structure, to achieve pre-compression and venting of the thick gradient side area, ensuring the density of the prepreg and reducing the risk of resin enrichment formation.

[0109] Specifically, the three preloading fixtures include a first preloading fixture 51, a second preloading fixture 52, and a third preloading fixture 53. The structure of the first preloading fixture 51 is shown in Figures 9A-9B; it is a ring-like structure with a corner structure 51a on its lower end face, adapting to the inclined surface of the component's gradually changing cross-section. The structure of the second preloading fixture 52 is shown in Figure 10, and the structure of the third preloading fixture 53 is shown in Figures 11A-11B; both are ring-like structures.

[0110] The two auxiliary positioning fixtures specifically include a first positioning fixture 54 and a second positioning fixture 55, the structures of which are shown in Figures 11A-11B. The first positioning fixture 54 is a circular shield type structure; the second positioning fixture 55 is a quasi-circular structure, including an inner thick ring surface 55a and an outer thin ring surface 55b.

[0111] Using the above five types of tooling, a total of two pre-compaction processes are carried out during the layup of the inclined surface of the component groove structure:

[0112] The first pre-compression is shown in Figure 12A. The first pre-compression fixture 51 and the second pre-compression fixture 52 are used together for pre-compression. The area within the elliptical dashed box is the pre-compression area. The corner structure 51a of the first pre-compression fixture 51 is matched and adapted to the gradient area of ​​the component, i.e., the inclined forming surface 22a. The second pre-compression fixture 52 works in conjunction with the first pre-compression fixture 51 to compensate for the height difference and transmit the press pressure.

[0113] The second pre-compression is shown in Figure 12B. The first pre-positioning fixture 54, the second pre-positioning fixture 55, and the third pre-compression fixture 53 work together for pre-compression. The area within the elliptical dashed box is the pre-compression area. The first pre-positioning fixture 54 mates with and is fixed to the pre-positioning core block 32 of the molding die, positioned on the outside of the core block 32 to occupy space between the outer slope of the core block 32 and the slope of the gradient area of ​​the component's groove structure. The outer side of the second pre-positioning fixture 55 mates with the middle frame edge strip 40, occupying space at the cavity where the slope of the gradient area meets the skin. Finally, the third pre-compression fixture 53 is used to transmit pressure, pre-compress and degas the material, increasing the density of the prepreg.

[0114] III. Molding Method

[0115] This embodiment discloses a molding method for a composite material component with a gradient cross-section based on the above-mentioned molding mold. Figure 13 shows the general process of component molding, where the black line represents the prepreg used for laying. The shape of the prepreg used for laying is shown in Figure 14, and the specific steps include:

[0116] S1: A layer of carbon fiber prepreg is laid on the entire molding area of ​​the bottom mold 20 as a base layer. The molding area covered by this base layer includes the areas of the inclined molding surface 22a, the annular lower molding surface 23, the annular rib molding groove 23a, and the strip rib molding groove 23b.

[0117] S2: Lay up the prepreg material at the bottom step of the groove at the position of the inclined forming surface 22a.

[0118] S3: Place the occupier core blocks 32 sequentially into the annular cavity 22 on the bottom mold 20, including first placing the forward slope core block 32a in sequence, and finally placing the reverse slope core block 32b from the inside to the outside into the empty position to occupy the cavity, and finally placing the center core block 31.

[0119] S4: Lay up the prepreg in the gradient area of ​​the component at position 22a of the inclined forming surface.

[0120] S5: During and after the layup of the gradient zone, the two pre-compaction processes mentioned above are performed to remove the air accumulated between the prepregs during the layup process, ensure the density of the prepreg, and improve the quality of component molding.

[0121] Specifically, the first pre-compression fixture 51 and the third pre-compression fixture 53 are placed on the press template and heated to 50±10℃ to soften the prepreg material they come into contact with. When half of the inclined forming surface 22a is laid up, the first pre-compression is performed. An appropriately sized release film is cut and covered on the bottom mold area to prevent material from sticking after the fixtures are pre-compressed. The first pre-compression fixture 51 is placed, followed by the second pre-compression fixture 52. After unscrewing the lifting ring, the first pre-compression is performed, and the press is used to pre-compress until the gap is tightly closed.

[0122] After pre-compression is completed, remove the tooling and release film, and then continue to complete the remaining layup in the gradient zone. After completion, place the release film and the first and second positioning tooling 54 and the second positioning tooling 55, and then place the third pre-compression tooling 53. After the two are used together, perform the second pre-compression. After unscrewing the lifting ring, use the press to pre-compress to the tight gap, and complete the two pre-compression processes.

[0123] S6: Prepreg lay-up in the annular rib forming groove 23a and the strip rib forming groove 23b.

[0124] S7: Perform skin lay-up at point 23 on the lower ring forming surface.

[0125] S8: Lay up a full layer of carbon fiber prepreg on the top surface of the component. After all layers are laid up, close the mold and cure according to the predetermined procedure to obtain a composite material component with a gradient cross-section.

[0126] In the layering process, the carbon cloth is laid as the base layer and then the stepped part is laid on the bottom side of the groove. After that, the excess material is trimmed off along the edge.

[0127] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the protection scope of the present invention, which is defined by the claims.

Claims

1. A molding die for a composite material component with a gradient cross-section, wherein the composite material component with a gradient cross-section is generally annular, including a central annular groove structure (01), the outer side of the groove structure (01) is an annular skin (02), the skin (02) is provided with reinforcing ribs (03), the reinforcing ribs (03) specifically include the outermost annular rib (03a) and four strip ribs (03b) connecting the groove structure (01) and the annular rib (03a), the cross-section of the groove structure (01) is a gradient region cross-section, its inner side is a groove (01a), below the groove (01a) is a bottom step (01b), and the outer side is an inclined surface (01c), the inclined surface (01c) is smoothly connected to the skin (02); characterized in that, The molding die includes: an upper mold (10) with a bottom surface comprising an annular upper molding surface (13) for molding the top surface of the skin (02) of the component; and a bottom mold (20) with a top surface comprising a concentric circular groove (21), an annular cavity (22), an annular lower molding surface (23), an annular movable area (24), and an annular edge (25) from the inside out. The outer edge of the annular cavity (22) includes an inclined molding surface (22a) for molding the component. The groove structure (01) has an inclined surface, and the annular lower forming surface (23) includes an annular rib forming groove (23a) and four radial strip rib forming grooves (23b) located on the outer edge. The annular lower forming surface (23) is used to form the bottom surface of the skin (02) of the component; the core block (30) includes a central core block (31) and several occupant core blocks (32); one of the occupant core blocks (32) is a reverse inclined core block (32b), and the rest are positive inclined core blocks (32a); all occupant core blocks (32) The components are assembled around the central core block (31) to form a disc shape. Each of the occupier core blocks (32) has a boss (32c) on its side. After assembly, the bosses (32c) form an annular shape and are used to form the groove (01a) of the molding component. During mold assembly, the lower end of the central core block (31) is placed in the circular groove (21) of the bottom mold (20), and the occupier core block (32) is placed in the annular cavity (22) of the bottom mold (20). The middle frame edge strip (40) includes four independent edge strips, which form an annular shape when assembled. The mold is placed in the annular movable area (24) of the bottom mold (20) during assembly. Each side strip is provided with at least a glue flow groove (41). Each side strip of the middle frame (40) includes a top screw groove (43) on its side. The bottom mold (20) is provided with several top screw holes evenly distributed around its edge, and top screws (25a) are screwed in. The end of the top screw (25a) cooperates with the top screw groove (43) to control the tightness of the middle frame (40) and to close the middle side strip after the material is filled.

2. The molding die as described in claim 1, characterized in that, The upper mold (10) also includes a circular positioning hole (11) located in the center for limiting the upper end of the center core block (31); the bottom surface of the upper mold (10) also includes an annular positioning groove (12) for limiting the occupier core block (32).

3. The molding die as described in claim 1, characterized in that, The diameter of the upper and lower ends of the central core block (31) is smaller than that of the middle part, and the side of the middle part is a slope, with the upper end of the slope tilting outward.

4. The molding die as described in claim 1, characterized in that, The center core block (31) has a screw hole (31a) at its center, and screws are used to fix it to the bottom mold (20) through the screw hole (31a).

5. The molding die as described in claim 1, characterized in that, The outer surface of the occupier (32) includes a slope, which is the surface between the upper edge and the boss (32c), with the upper edge sloping inward.

6. The molding die as described in claim 1, characterized in that, Each of the side strips (40) of the middle frame contains two glue channels (41) located on the top surface.

7. The molding die as described in claim 1, characterized in that, Each of the middle frame edge strips (40) includes a limiting groove (42) located on the bottom surface; the annular movable area (24) of the bottom mold (20) includes four radial limiting blocks (24a) for cooperating with the limiting grooves (42) to circumferentially limit the middle frame edge strips (40).

8. A molding method for a composite material component with a gradient cross-section, wherein the component is molded using a molding die according to any one of claims 1-7, characterized in that, Includes the following steps: A layer of carbon fiber prepreg is laid as the base layer in the entire molding area of ​​the bottom mold (20). This entire molding area includes the area where the inclined molding surface (22a), the annular lower molding surface (23), the annular rib molding groove (23a), and the strip rib molding groove (23b) are located. A layer of prepreg is laid on the bottom side step of the groove at the position of the inclined molding surface (22a). The positive inclined core block (32a) of the occupant core block (32) is placed in the annular cavity (22) of the bottom mold (20) in sequence, and finally the reverse inclined core block (32a) is installed. b), perform cavity placement; after the placement core block (32) is placed, place the center core block (31); lay up the prepreg in the gradient area of ​​the component at the position of the inclined forming surface (22a); lay up the prepreg in the annular rib forming groove (23a) and the strip rib forming groove (23b); lay up the skin at the annular lower forming surface (23); lay up a whole layer of carbon cloth prepreg on the top layer of the component; after all the layup is completed, close the mold and cure according to the predetermined procedure to obtain a composite material component with gradient cross-section characteristics.

9. The molding method as described in claim 8, characterized in that, During and after the carbon fiber prepreg layering process in the gradient area of ​​the component, two pre-compaction operations are performed, including: heating the first pre-compression fixture (51) and the third pre-compression fixture (53); when half of the inclined forming surface (22a) is laid, the first pre-compression operation is performed: laying the release film, using the corner structure (51a) of the first pre-compression fixture (51) to cooperate with the inclined forming surface (22a), and pressing the second pre-compression fixture (52) on the first pre-compression fixture (51) for cooperation and compaction; removing the first pre-compression fixture (51), the second pre-compression fixture (52) and the release film. Continue to lay the remaining layers, and after completion, perform the second pre-compaction operation: lay the release film and place the first occupant fixture (54) and the second occupant fixture (55). The first occupant fixture (54) is placed outside the occupant core block (32) and cooperates with and fixes the occupant core block (32); the second occupant fixture (55) is placed in the annular lower forming surface (23) area of ​​the bottom mold (20) and cooperates with the middle frame edge strip (40) on the outside; finally, place the third pre-compaction fixture (53) between the first occupant fixture (54) and the second occupant fixture (55) for pre-compaction.

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