A forming die and forming process for a carbon fiber composite material skin

Abstract

This invention relates to the field of composite material preparation technology, specifically disclosing a molding die and molding process for carbon fiber composite skin. The invention uses unidirectional carbon fiber prepreg and carbon fiber fabric prepreg as raw materials, employing a prepreg flanging and twisting method for integral curing, ensuring fiber continuity at corners and providing strength and stiffness in the main load-bearing direction. The mold structure and process of this invention are simple and easy to operate. Through mold design and layup design, fiber continuity is ensured, increasing the overall strength of the product and avoiding processing risks. The product quality is stable, and the product dimensions are precisely controllable, making it suitable for mass production.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, and in particular to a molding die for carbon fiber composite skin and its molding process. Background Technology

[0002] With the continuous development of weaponry and equipment, the requirements for performance such as weight reduction, stealth, impact resistance, and high temperature resistance are becoming increasingly higher. Traditional metal materials are finding it increasingly difficult to meet these requirements, and composite materials have become the foundation of military equipment development. Their application level has become one of the standards for measuring the advancement of weaponry and equipment development.

[0003] As the cost of composite materials decreases, their application in weaponry continues to increase. The use of composite materials in the skin significantly reduces the overall weight of the equipment, increases its flight speed, and extends its launch range. Summary of the Invention

[0004] The purpose of this invention is to provide a molding die for carbon fiber composite skin and its molding process to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides a molding die for a carbon fiber composite skin, comprising:

[0006] The lower mold has a product groove and multiple positioning pins and multiple threaded holes.

[0007] A side baffle is installed on one side of the lower mold via a positioning pin, and the side baffle is fixed to the lower mold by bolts and threaded holes; the product groove is enclosed by the side baffle to form a product cavity;

[0008] The upper cover plate is disposed at one top end of the lower mold. The upper cover plate is installed on the lower mold by the positioning pin, and the upper cover plate and the lower mold are fixed together by bolts and threaded holes. The upper cover plate is used to install a drill bushing with forming and hole-making functions.

[0009] A molding process for carbon fiber composite skin specifically includes the following steps:

[0010] S1. The first prepreg is laid in the product cavity of the lower mold, so that the first prepreg is turned up at the position of the upper cover plate;

[0011] S2. Fill the flange of the first prepreg with twist and compact the twist;

[0012] S3. Lay the second prepreg, turn the second prepreg at the position of the twist strip, and compact the second prepreg at the twist strip;

[0013] S4. Fill the flange of the second prepreg with twist strips and compact the twist strips;

[0014] S5. Lay out multiple layers of the second prepreg in sequence to obtain a pre-formed product;

[0015] S6. Cure the initially formed product and then make holes in the cured product.

[0016] S7. Demold the product after hole making, and trim and install wire thread inserts.

[0017] Preferably, the first prepreg is a carbon fiber fabric prepreg, and the second prepreg is a unidirectional carbon fiber prepreg.

[0018] Preferably, the wire thread insert is installed at the angle between the upper cover plate and the lower mold of the product, and the product thickness at the installation position of the wire thread insert is 10mm.

[0019] Preferably, the drilling direction of the product is consistent with the normal direction of the drilling position.

[0020] Preferably, each prepreg layer of the product extends to the edge of the product groove.

[0021] Preferably, step S5 includes:

[0022] S5.1 When the carbon fiber unidirectional prepreg is laid to the last two layers, use bolts to install the side baffle on the lower mold, and use carbon fiber unidirectional prepreg to fill and compact the gap between the lower mold and the side baffle.

[0023] S5.2 Remove the side panels and lay the last two layers of carbon fiber unidirectional prepreg on the lower mold to cover the entire product.

[0024] Preferably, before step S6, the bolts used to fix the side baffle are removed.

[0025] Preferably, before drilling holes in the cured product, the auxiliary materials on the cured product are removed, and a drill bushing is installed on the top cover plate.

[0026] A carbon fiber composite skin is prepared using the above-mentioned molding process for carbon fiber composite skin.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] 1. Existing skins are mostly made of aluminum alloy, which is relatively heavy. This invention uses carbon fiber unidirectional prepreg and carbon fiber fabric prepreg as raw materials, and adopts the method of prepreg flanging and twisting to integrally cure and form, which reduces the overall weight by about 50%.

[0029] 2. This invention proposes a molding process for composite material skin. Through mold structure design, the continuity of fibers and the requirements of internal and external surfaces are ensured. The carbon fiber prepreg can accurately control the resin content of the product, strictly control the weight of the product, and ensure batch stability.

[0030] 3. The mold structure and process of this invention are simple and easy to operate. Through mold design and layup design, the continuous fiber is ensured to increase the overall strength of the product and avoid processing risks. The product quality is stable and the product shape and size are precisely controllable, making it suitable for mass production. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. 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 effort.

[0032] Figure 1 This is a schematic diagram of the assembled composite material skin molding die of the present invention;

[0033] Figure 2 This is a schematic diagram of the disassembled composite material skin molding die of the present invention;

[0034] Figure 3 This is a schematic diagram of the application of the composite material skin of the present invention;

[0035] In the diagram: 1. Lower mold; 2. Side baffle; 3. Upper cover plate; 4. Locating pin; 5. Product groove; 6. Threaded hole; 7. Drill die bushing. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] like Figures 1 to 3 As shown, the present invention provides a molding die for a carbon fiber composite skin, comprising:

[0038] The lower mold 1 has a product groove 5, and multiple positioning pins 4 and multiple threaded holes 6 are provided on the lower mold 1.

[0039] Side baffle 2 is installed on one side of the lower mold 1 by positioning pin 4, and the side baffle 2 and the lower mold 1 are fixed together by bolts and threaded holes 6; the product groove 5 is enclosed by the side baffle 2 to form a product cavity;

[0040] The upper cover plate 3 is located at one top end of the lower mold 1. The upper cover plate 3 is installed on the lower mold 1 by a positioning pin 4, and the upper cover plate 3 and the lower mold 1 are fixed together by bolts and threaded holes 6. The upper cover plate 3 is used to install the drill bushing 7 with forming and hole-making functions.

[0041] The upper cover plate 3 of this invention serves as both a forming mold and a hole-making tooling. After forming is completed, the drill jig bushing 7 can be installed before hole making to create the hole. This ensures that hole making can be completed without demolding, guaranteeing the positional and dimensional accuracy of the hole.

[0042] A molding process for carbon fiber composite skin specifically includes the following steps:

[0043] S1. The first prepreg is laid in the product cavity of the lower mold 1, so that the first prepreg is turned over at the position of the upper cover plate 3.

[0044] S2. Fill the flange of the first prepreg with twist and compact the twist;

[0045] S3. Lay the second prepreg, turn the second prepreg at the position of the twist strip, and compact the second prepreg at the twist strip;

[0046] S4. Fill the flange of the second prepreg with twist strips and compact the twist strips;

[0047] S5. Lay out multiple layers of the second prepreg in sequence to obtain a pre-formed product;

[0048] S6. Cure the initially formed product and then make holes in the cured product.

[0049] S7. Demold the product after hole making, and trim and install wire thread inserts.

[0050] The scheme was further optimized so that the first prepreg is a carbon fiber fabric prepreg and the second prepreg is a unidirectional carbon fiber prepreg.

[0051] The design was further optimized so that the wire thread insert is installed at the angle between the upper cover plate 3 and the lower mold 1 of the product, and the thickness of the product at the installation position of the wire thread insert is about 10mm.

[0052] The design was further optimized so that the drilling direction of the product is consistent with the normal direction of the drilling location.

[0053] The design was further optimized so that each prepreg layer of the product was laid to the edge of the groove 5 of the product.

[0054] Further optimization of the solution, the S5 steps include:

[0055] S5.1 When the carbon fiber unidirectional prepreg is laid to the last two layers, use bolts to install the side baffle 2 on the lower mold 1, and use carbon fiber unidirectional prepreg to fill and compact the gap between the lower mold 1 and the side baffle 2.

[0056] S5.2 Remove the side baffle 2 and lay the last two layers of carbon fiber unidirectional prepreg on the lower mold 1 to cover the entire product.

[0057] To further optimize the solution, before step S6, remove the bolts used to fix the side baffle 2.

[0058] To further optimize the solution, before drilling holes in the cured product, remove the auxiliary materials on the cured product and install the drill bushing 7 on the upper cover plate 3.

[0059] A carbon fiber composite skin is prepared using the above-mentioned molding process for carbon fiber composite skin.

[0060] The molding process for carbon fiber composite skin provided by this invention involves first positioning the upper cover plate 3 on the lower mold 1 before laying, while the side baffles 2 are not installed yet. The carbon fiber prepreg is laid as the first layer on the lower mold 1, with the upper cover plate 3 being flanged to ensure fiber continuity. After the first layer is laid, a small amount of twisted strips is filled and compacted at the corners before laying the unidirectional carbon fiber prepreg. The unidirectional carbon fiber prepreg remains continuous at the corners of the lower mold 1 and the upper cover plate 3. Twisted strips are then added in a measured quantity.

[0061] When the last two layers of unidirectional carbon fiber prepreg are laid, fix the side baffle 2 with positioning pins 4 and tighten it with bolts. Fill and compact the gap between the lower mold 1 and the side baffle 2 with unidirectional carbon fiber prepreg. After compaction, remove the side baffle 2 and lay the last two layers of unidirectional carbon fiber prepreg on the lower mold 1 to cover the entire product. The layup at the upper cover plate 3 is slightly higher than the edge of the upper cover plate 3 mold. All product layups are laid to the edge of the product groove 5 to ensure that no material squeezing occurs when the side baffle 2 is closed.

[0062] After the tiling is completed, use the positioning pins 4 to fix the side baffle 2 in the corresponding position before sealing. Do not install bolts to ensure that the side baffle 2 is fixed in position during the curing process and can continuously apply pressure to the side of the product.

[0063] The thickness of the product groove 5 in the lower mold 1 is set according to the product thickness, which can ensure the product thickness and prevent excessive resin loss during the curing process.

[0064] After curing, remove the auxiliary materials and install the drill bushing 7 on the upper cover plate 3 to make holes. When making holes, both the inner and outer surfaces are made of prepreg fabric to avoid surface splitting. The hole making direction is consistent with the normal direction of the carbon fiber layup to avoid internal overall splitting.

[0065] After the holes are made, demolding is performed. After demolding, trimming and installation of wire thread inserts are carried out.

[0066] This invention mainly uses carbon fiber unidirectional prepreg as raw material to ensure fiber continuity at corners and provide strength and stiffness in the main load-bearing direction. It adopts the method of prepreg flanging and twisting to integrally cure and form the product. The amount of twist filling can be strictly controlled by the upper cover plate 3 and the side baffle 2, which can effectively control the weight of the product, ensure product quality stability and weight consistency, and ensure the stability of product batches.

[0067] The composite material skin prepared by this invention has advantages such as light weight and easy installation. The molding process is simple and easy to operate, the product's dimensions are precisely controllable, and the surface is smooth and flat, making it suitable for mass production.

[0068] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A molding process for carbon fiber composite skin, characterized in that, Specifically, the following steps are included: S1. The first prepreg is laid in the product cavity of the lower mold (1) so that the first prepreg is turned over at the position of the upper cover plate (3); S2. Fill the flange of the first prepreg with twist and compact the twist; S3. Lay the second prepreg, turn the second prepreg at the position of the twist strip, and compact the second prepreg at the twist strip; S4. Fill the flange of the second prepreg with twist strips and compact the twist strips; S5. Lay out multiple layers of the second prepreg in sequence to obtain a pre-formed product; S6. Cure the initially formed product and then make holes in the cured product. S7. Demold the product after drilling, and trim the edges and install the wire thread insert; The first prepreg is a carbon fiber fabric prepreg, and the second prepreg is a unidirectional carbon fiber prepreg; Step S5 includes: S5.1 When the carbon fiber unidirectional prepreg is laid to the last two layers, use bolts to install the side baffle (2) on the lower mold (1), and use carbon fiber unidirectional prepreg to fill and compact the gap between the lower mold (1) and the side baffle (2); S5.2 Remove the side baffle (2) and lay the last two layers of carbon fiber unidirectional prepreg on the lower mold (1) to cover the product. Before step S6, remove the bolts used to fix the side baffle (2); Before drilling holes in the cured product, remove the auxiliary materials on the cured product and install the drill bushing (7) on the upper cover plate (3).

2. The molding process of the carbon fiber composite skin according to claim 1, characterized in that, The wire thread insert is installed at the angle between the upper cover plate (3) and the lower mold (1) of the product, and the thickness of the product at the installation position of the wire thread insert is 10mm.

3. The molding process of the carbon fiber composite skin according to claim 1, characterized in that, The drilling direction of the product is consistent with the normal direction of the drilling position.

4. The molding process of the carbon fiber composite skin according to claim 1, characterized in that, Each prepreg layer of the product is laid to the edge of the product groove (5).

5. A molding die for a carbon fiber composite skin, used to implement the molding process of the carbon fiber composite skin according to any one of claims 1-4, characterized in that, include: The lower mold (1) has a product groove (5) and multiple positioning pins (4) and multiple threaded holes (6). Side baffle (2), the side baffle (2) is installed on one side of the lower mold (1) by the positioning pin (4), and the side baffle (2) and the lower mold (1) are fixed by bolts and threaded holes (6); the product groove (5) is enclosed by the side baffle (2) to form a product cavity; The upper cover plate (3) is located at the top end of the lower mold (1). The upper cover plate (3) is installed on the lower mold (1) by the positioning pin (4), and the upper cover plate (3) and the lower mold (1) are fixed together by bolts and the threaded hole (6). The upper cover plate (3) is used to install the drill bushing (7) with forming and hole-making functions.

6. A carbon fiber composite skin, characterized in that, The carbon fiber composite skin is prepared using the molding process described in any one of claims 1-4.

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