Forming die and manufacturing method of composite material polygonal pipe

Abstract

The invention belongs to the technical field of composite material manufacturing, and provides a forming mold and a manufacturing method of a composite material polygonal pipe, and the manufacturing method comprises the following steps: S1, paving carbon fiber prepreg on a forming surface of a core mold; s2, a plurality of outer mold flat plate blocks are correspondingly installed on the outer surface where the prepreg is laid, the outer mold flat plate blocks are fixedly connected with the core mold through positioning connecting pieces, and an outer mold R-angle block is placed between every two outer mold flat plate blocks; s3, packaging the core mold, the outer mold flat plate block and the outer mold R-angle block to form a vacuum sealing bag; s4, the packaged mold is conveyed to an autoclave for curing; and S5, after curing is completed, the core mold, the outer mold flat plate block and the outer mold R-angle block are removed, and the composite material polygonal pipe is obtained. On the premise of ensuring the dimensional precision of the inner and outer molded surfaces, the problems that the continuity of fibers is damaged and the void ratio of the R angle is poor can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material manufacturing, and in particular relates to a forming die and a manufacturing method of a composite material polygonal tube. Background Art

[0002] Composite pipe parts are widely used, and their light weight and high strength are particularly suitable for the aerospace field. Traditional composite pipes generally use a molding process to ensure the dimensional accuracy of the internal and external surfaces. Affected by the properties of the composite material itself, the thickness of the composite prepreg before curing is greater than the thickness after curing. This characteristic will cause the preformed parts to be thicker after laying. The upper and lower parting structures of traditional pipe parts are easily clamped at the parting surface during the curing process, resulting in the destruction of the continuity of the outermost fibers. In addition, the R corner cannot provide good pressure for the parts due to the overall structure of the mold, resulting in poor R corner porosity and even bridging. Summary of the invention

[0003] The purpose of the present invention is to provide a forming die and a manufacturing method for a composite polygonal tube to solve the above problems and achieve the purpose of solving the problems of fiber continuity being destroyed and R angle void ratio being poor while ensuring the dimensional accuracy of the inner and outer surfaces.

[0004] To achieve the above object, the present invention provides the following solution: a forming die for a composite polygonal tube, comprising:

[0005] A core mold, wherein the core mold is a prism structure, and the side surfaces of the core mold are all molding surfaces;

[0006] The outer mold assembly includes a plurality of outer mold flat plates and a plurality of outer mold R corner blocks. The plurality of outer mold flat plates are respectively arranged corresponding to the respective forming surfaces of the core mold, and a positioning connector is arranged between the outer mold flat plates and the core mold. The outer mold R corner block is arranged between two adjacent outer mold flat plates, and the outer mold R corner block is adapted to the edge of the outer mold flat plate.

[0007] Preferably, both ends of the several molding surfaces of the core mold are respectively provided with an annular core mold margin line and a core mold product line, the core mold margin line is located outside the core mold product line, and the positioning connector is arranged outside the core mold margin line.

[0008] Preferably, the positioning connector includes two groups of core mold positioning holes and two groups of core mold bolt holes opened on the core mold forming surface, the two core mold positioning holes and the two core mold bolt holes are respectively located at two ends of the core mold forming surface, and a positioning pin is fixedly connected in the core mold positioning hole;

[0009] It also includes two groups of outer mold positioning holes and two groups of outer mold connecting holes opened on the outer mold flat plate. The two outer mold positioning holes and the two outer mold connecting holes are respectively located at the two ends of the outer mold flat plate. The outer mold positioning holes are arranged corresponding to the positioning pins, and the outer mold connecting holes are detachably connected to the core mold bolt holes by bolts.

[0010] Preferably, core mold through holes are provided at both ends of the core mold along the axis of the core mold.

[0011] A method for manufacturing a composite polygonal tube comprises the following steps:

[0012] S1. Laying carbon fiber prepreg on the molding surface of the core mold;

[0013] S2. Install several outer mold flat plates on the outer surface where the prepreg is laid, and use positioning connectors to fix the several outer mold flat plates to the core mold, and place an outer mold R corner block between the two outer mold flat plates;

[0014] S3, encapsulating the core mold, the outer mold flat plate and the outer mold R corner block to form a vacuum sealed bag;

[0015] S4, sending the encapsulated mold to an autoclave for curing;

[0016] S5. After curing is completed, the core mold, the outer mold flat plate and the outer mold R corner block are removed to obtain a composite material polygonal tube.

[0017] Preferably, both ends of the plurality of molding surfaces of the core mold are respectively provided with an annular core mold margin line and a core mold product line, the core mold margin line is located outside the core mold product line, and the positioning connector is arranged outside the core mold margin line. In step S1, both sides of the laid carbon fiber prepreg should exceed the core mold margin line, and unvulcanized rubber ribs are used;

[0018] The paving process requires multiple vacuuming and tank pre-pressing.

[0019] Preferably, in step S2, after placing the outer mold R corner block, a high temperature resistant tape is used to fix the outer mold R corner block.

[0020] Preferably, in step S3, after the core mold is molded with a plurality of outer mold flat plates and outer mold R corner blocks, the outer layer is sequentially covered with an isolation film, a breathable felt and a vacuum bag to encapsulate the core mold, the outer mold flat plates and the outer mold R corner blocks;

[0021] Auxiliary materials need to be placed on the outside of the outer mold flat plate, the outer mold R corner block, and the inside of the core mold to form a vacuum sealed bag.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] 1. The present invention proposes a molding die and a manufacturing method for a composite polygonal tube. After prepreg is laid on the surface of the core mold, each molding surface and R angle are divided into blocks along the R angle edge by an outer mold assembly. During the curing stage of the autoclave process, each outer module can be simultaneously pressurized and moved toward the axis to apply uniform, synchronous and stable pressure to the parts, thereby obtaining a composite polygonal tube with precise product size, continuous fibers and low void ratio.

[0024] 2. Affected by the properties of the composite material itself, the thickness of the composite material prepreg before curing is greater than the thickness after curing. This feature will cause the preformed part to be thicker after laying. Compared with the traditional tube parts, the upper and lower parting structures are very easy to get caught in the cloth at the parting surface during the curing process, which leads to the destruction of the outermost fiber continuity and reduced part performance. The present invention divides the outer mold into blocks along the R-angle edge, and each plane area and R-angle area of ​​the polygonal tube will have a separate outer module. The pre-installation process before curing will evenly distribute the impact of the thick part, and the fiber continuity will not be destroyed due to the cloth being caught.

[0025] 3. Compared with the traditional autoclave process, although the auxiliary materials on the outer surface of the parts can provide uniform, continuous and stable pressure for the parts, the outer surface of the parts is not smooth, and the size and appearance do not meet the requirements of pipe products. On this basis, the present invention adds an outer mold component to the outer surface of the part, and utilizes the smooth surface of the outer mold component to contact the workpiece, so that the internal quality of each area can meet the aerospace quality level requirements while the workpiece meets the dimensional accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the core mold of the present invention;

[0028] Figure 2 It is a schematic diagram of the mold assembly of the core mold, the outer mold flat plate, and the outer mold R corner block of the present invention;

[0029] Figure 3 The polygonal composite material tube after demoulding according to the embodiment of the present invention;

[0030] Among them, 1. core mold; 2. core mold allowance line; 3. core mold product line; 4. core mold positioning hole; 5. core mold bolt hole; 6. outer mold flat plate; 7. outer mold R corner block; 8. core mold through hole; 9. outer mold positioning hole; 10. outer mold connecting hole. DETAILED DESCRIPTION

[0031] The following will be combined with the 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 described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Embodiment 1:

[0034] Reference Figure 1-Figure 3 The present invention provides a forming die for a composite material polygonal tube, comprising:

[0035] The core mold 1 is a prism structure, and the side surfaces of the core mold 1 are all molding surfaces;

[0036] The outer mold assembly includes a plurality of outer mold flat plates 6 and a plurality of outer mold R corner blocks 7. The plurality of outer mold flat plates 6 are respectively arranged corresponding to the respective forming surfaces of the core mold 1, and a positioning connector is arranged between the outer mold flat plates 6 and the core mold 1. The outer mold R corner block 7 is arranged between two adjacent outer mold flat plates 6, and the outer mold R corner block 7 is adapted to the edge of the outer mold flat plate 6.

[0037] The core mold 1 is a metal positive mold, and its main function is to facilitate the laying of carbon fiber unidirectional prepreg, and to define the structure of the composite polygonal tube through its own geometric shape; a number of outer mold flat blocks 6 and a number of outer mold R angle blocks 7 can form a metal modular mold block, and its main function is to apply uniform, synchronous and stable pressure to the parts during the curing stage. On the whole, the present invention divides each molding surface and R angle into blocks along the R angle edge of the outer mold, and during the curing stage, the outer module can be pressurized and moved synchronously into the axis to apply uniform, synchronous and stable pressure to the parts, thereby obtaining a composite polygonal tube with precise product size, continuous fibers, low porosity and high internal quality in each area; at the same time, the outer mold block processing can also evenly distribute the impact of the thick part before curing, and the fiber continuity will not be destroyed due to the clamping of the cloth.

[0038] To further optimize the solution, the structures of the core mold 1 and the outer mold assembly can be customized according to the required structure of the composite polygonal tube, so that the composite polygonal tube can be a tube of uniform cross-section or a tube of non-uniform cross-section, and the number and geometric dimensions of the edges of the workpiece can be adjusted according to different load conditions.

[0039] According to a further optimization scheme, an annular core mold margin line 2 and a core mold product line 3 are respectively provided at both ends of several molding surfaces of the core mold 1, the core mold margin line 2 is located outside the core mold product line 3, and the positioning connector is provided outside the core mold margin line 2.

[0040] like Figure 1 As shown, the main function of the core mold margin line 2 is to provide a boundary reference for the laying of the carbon fiber unidirectional prepreg and to ensure that the demoulding part has sufficient processing margin after curing.

[0041] Further optimizing the scheme, the positioning connector includes two groups of core mold positioning holes 4 and two groups of core mold bolt holes 5 opened on the molding surface of the core mold 1, the two core mold positioning holes 4 and the two core mold bolt holes 5 are respectively located at both ends of the molding surface of the core mold 1, and the core mold positioning holes 4 are fixedly connected with positioning pins;

[0042] It also includes two groups of outer mold positioning holes 9 and two groups of outer mold connecting holes 10 opened on the outer mold flat plate 6. The two outer mold positioning holes 9 and the two outer mold connecting holes 10 are respectively located at the two ends of the outer mold flat plate 6. The outer mold positioning holes 9 are correspondingly arranged with the positioning pins. The outer mold connecting holes 10 are detachably connected to the core mold bolt holes 5 by bolts.

[0043] like Figure 2 As shown, the outer mold flat plate 6 can be prevented from falling by threading the bolts through the outer mold connection holes 10 and the core mold bolt holes 5. The positioning pins and the outer mold positioning holes 9 can be used for sliding connection to provide positioning for the installation of the outer mold flat plate 6, and to provide a limit for the movement of the outer mold flat plate 6 in the axial direction during the curing stage, so as to accurately apply pressure to the parts.

[0044] According to a further optimized solution, core mold through holes 8 are provided at both ends of the core mold 1 along the axis of the core mold 1 .

[0045] like Figure 2 As shown, the main function of the core mold through hole 8 is to facilitate air circulation during the curing stage, that is, the core mold through hole 8 can make the air in the autoclave contact various parts of the core mold 1 more quickly, especially the part close to the middle of the core mold 1, which can improve the heat transfer efficiency.

[0046] Embodiment 2:

[0047] A method for manufacturing a composite polygonal tube comprises the following steps:

[0048] S1, laying carbon fiber prepreg on the molding surface of the core mold 1;

[0049] S2. Install a number of outer mold flat blocks 6 corresponding to the outer surface on which the prepreg is laid, and use positioning connectors to fix the outer mold flat blocks 6 to the core mold 1, and place an outer mold R corner block 7 between two outer mold flat blocks 6;

[0050] In step S2, after the outer mold flat plate 6 is inserted into the positioning pin, a bolt is used to penetrate the outer mold connecting hole 10 and connected to the core mold bolt hole 5, and the outer mold flat plate 6 is placed to fall.

[0051] S3, encapsulating the core mold 1, the outer mold flat block 6 and the outer mold R corner block 7 to form a vacuum sealed bag;

[0052] S4, sending the encapsulated mold to an autoclave for curing;

[0053] S5. After curing is completed, the core mold 1, the outer mold flat block 6 and the outer mold R corner block 7 are removed to obtain a composite material polygonal tube.

[0054] Further optimizing the scheme, the two ends of the several molding surfaces of the core mold 1 are respectively provided with an annular core mold margin line 2 and a core mold product line 3, the core mold margin line 2 is located outside the core mold product line 3, and the positioning connector is arranged outside the core mold margin line 2. In step S1, both sides of the laid carbon fiber prepreg should exceed the core mold margin line 2, and unvulcanized rubber retaining edges are used;

[0055] The paving process requires multiple vacuuming and tank pre-pressing.

[0056] To further optimize the solution, in step S2, after placing the outer mold R corner block 7, use a high temperature resistant tape to fix the outer mold R corner block 7.

[0057] Further optimizing the scheme, in step S3, after the core mold 1 is molded with a plurality of outer mold flat blocks 6 and outer mold R corner blocks 7, the outer layer is sequentially covered with an isolation film, a breathable felt and a vacuum bag to encapsulate the core mold 1, the outer mold flat blocks 6 and the outer mold R corner blocks 7;

[0058] Auxiliary materials need to be placed on the outer side of the outer mold flat block 6, the outer mold R corner block 7 and the inner side of the core mold 1 to form a vacuum sealed bag.

[0059] The specific implementation steps of this embodiment for a certain product are as follows:

[0060] Step S1, laying carbon fiber prepreg on the molding surface of the core mold 1, the prepreg laying needs to exceed the core mold margin line 2, and unvulcanized rubber retaining edges are used on the edges of the workpiece; during the laying process, vacuum pre-pressing is performed once every two layers, and the vacuum degree is required to be guaranteed to be above 0.08Mpa and last for more than 15min; every 6 layers are laid, the tank is put into the pre-pressing for heating, the pressure is 0.6Mpa, the temperature is increased by 60-70℃, and it lasts for more than 15min.

[0061] Step S2, such as Figure 2First, install each outer mold flat plate 6 on the outer surface of the core mold 1 with the prepreg laid, and use bolts to connect the outer mold connecting holes 10 and the core mold bolt holes 5 to prevent the outer mold flat plates 6 from falling; after all the outer mold flat plates 6 are installed, place each outer mold R corner block 7 between two adjacent outer mold flat plates 6, and use high temperature resistant tape to fix the outer mold R corner block 7 to prevent it from falling.

[0062] Step S3, encapsulate the mold after mold closing in the manner of mold → isolation film → breathable felt → vacuum bag. Auxiliary materials need to be placed on the outside of the outer mold assembly and the inside of the core mold 1 to form a vacuum sealing bag; after encapsulation, perform a leakage check, first evacuate the parts, the vacuum degree is not less than 0.092MPa, the parts are connected to the vacuum system for at least 15min, the vacuum system is turned off, and the vacuum gauge reading drops by no more than 0.002Mpa within 5min.

[0063] Step S4, sending the packaged mold to the autoclave for curing, initially pressurizing (0.6~0.7)Mpa, heating to 80±5℃, keeping the temperature constant for 30±5min, then heating to 120±5℃ and keeping the temperature constant for 120±30min, then cooling to below 60℃ and releasing the pressure to take it out of the autoclave; vacuumizing the whole curing process.

[0064] The pressure during the curing process comes from the compressed gas in the autoclave. As the temperature rises, the softening of the material will provide a stable and continuous pressure for the part, which is conducive to the discharge of gas and thus obtains high-quality parts. Because the outer mold structure is divided into blocks along the R angle line, each flat plate and R angle area will well transmit the pressure of the autoclave, thereby ensuring the internal quality of the part.

[0065] Step S5, after curing, the auxiliary materials and the outer mold components are removed, and the parts are removed from the core mold 1 along the length direction with the aid of a demoulding ring and a demoulding device;

[0066] Afterwards, the redundant parts are cut and removed according to the position of the core mold product line 3 reserved by the core mold 1 to obtain a composite polygonal tube, such as Figure 3 .

[0067] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0068] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A forming die for a composite polygonal tube, characterized in that: include: A core mold (1), wherein the core mold (1) is a prism structure, and the side surfaces of the core mold (1) are all molding surfaces; The outer mold assembly comprises a plurality of outer mold flat plates (6) and a plurality of outer mold R-angle blocks (7), wherein the plurality of outer mold flat plates (6) are respectively arranged corresponding to the respective molding surfaces of the core mold (1), and a positioning connection piece is arranged between the outer mold flat plates (6) and the core mold (1), and the outer mold R-angle block (7) is arranged between two adjacent outer mold flat plates (6), and the outer mold R-angle block (7) is adapted to the edge of the outer mold flat plate (6).

2. The forming die for a composite material polygonal tube according to claim 1, characterized in that: An annular core mold margin line (2) and a core mold product line (3) are respectively arranged at both ends of the plurality of molding surfaces of the core mold (1); the core mold margin line (2) is located outside the core mold product line (3); and the positioning connector is arranged outside the core mold margin line (2).

3. The forming die of a composite material polygonal tube according to claim 1, characterized in that: The positioning connecting member comprises two groups of core mold positioning holes (4) and two groups of core mold bolt holes (5) which are opened on the molding surface of the core mold (1); the two core mold positioning holes (4) and the two core mold bolt holes (5) are respectively located at two ends of the molding surface of the core mold (1); and a positioning pin is fixedly connected in the core mold positioning hole (4); It also includes two groups of outer mold positioning holes (9) and two groups of outer mold connecting holes (10) provided on the outer mold flat plate (6), the two outer mold positioning holes (9) and the two outer mold connecting holes (10) are respectively located at the two ends of the outer mold flat plate (6), the outer mold positioning holes (9) are arranged corresponding to the positioning pins, and the outer mold connecting holes (10) are detachably connected to the core mold bolt holes (5) by bolts.

4. The forming die for a composite material polygonal tube according to claim 1, characterized in that: Core mold through holes (8) are provided at both ends of the core mold (1) along the axis of the core mold (1).

5. A method for manufacturing a composite polygonal tube, based on the forming die of a composite polygonal tube according to claim 1, characterized in that: The following steps are involved: S1, laying carbon fiber prepreg on the molding surface of the core mold (1); S2. Install a plurality of outer mold flat plates (6) corresponding to the outer surface on which the prepreg is laid, and use positioning connectors to fix the plurality of outer mold flat plates (6) to the core mold (1), and place an outer mold R angle block (7) between two outer mold flat plates (6); S3, encapsulating the core mold (1), the outer mold flat plate (6) and the outer mold R corner block (7) to form a vacuum sealed bag; S4, sending the encapsulated mold to an autoclave for curing; S5. After curing is completed, the core mold (1), the outer mold flat plate (6) and the outer mold R angle block (7) are removed to obtain a composite material polygonal tube.

6. The method for manufacturing a composite polygonal tube according to claim 5, characterized in that: The two ends of the plurality of molding surfaces of the core mold (1) are respectively provided with an annular core mold margin line (2) and a core mold product line (3), the core mold margin line (2) is located outside the core mold product line (3), and the positioning connector is arranged outside the core mold margin line (2). In step S1, both sides of the laid carbon fiber prepreg should exceed the core mold margin line (2), and unvulcanized rubber retaining edges are used; The paving process requires multiple vacuuming and tank pre-pressing.

7. The method for manufacturing a composite material polygonal tube according to claim 5, characterized in that: In step S2, after placing the outer mold R corner block (7), the outer mold R corner block (7) is fixed using a high temperature resistant tape.

8. The method for manufacturing a composite polygonal tube according to claim 5, characterized in that: In step S3, after the core mold (1) is molded together with a plurality of outer mold flat plates (6) and outer mold R corner blocks (7), the outer layers are sequentially covered with an isolation film, a breathable felt and a vacuum bag to encapsulate the core mold (1), the outer mold flat plates (6) and the outer mold R corner blocks (7); Auxiliary materials need to be placed on the outer side of the outer mold flat plate (6), the outer mold R corner block (7) and the inner side of the core mold (1) to form a vacuum sealed bag.

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