A support structure for a composite mould and a method of manufacturing the same

Abstract

This invention relates to the field of composite material manufacturing technology, and provides a support structure for a composite mold and its manufacturing method, including composite material sheets and composite material corner pieces. Both the composite material sheets and the composite material corner pieces are composite laminates, and are connected by adhesive bonding and riveting to form a composite material frame. The composite material frame is connected to the composite mold surface by adhesive bonding and riveting. The support structure of this invention uses all composite material components, significantly reducing the overall weight of the mold. The support frame and the composite mold maintain consistent thermal expansion properties, eliminating additional stress caused by thermal expansion mismatch under thermal cycling, improving the molding accuracy of composite products, and extending the service life of the composite mold. The composite connection using adhesive bonding and riveting provides high structural strength and reliability, making it suitable for various composite material molding dies.

Description

Technical Field

[0001] This invention relates to the field of composite material manufacturing technology, and in particular to a support structure for a composite mold and its manufacturing method. Background Technology

[0002] Composite material molding dies (hereinafter referred to as composite molds) are widely used in the preparation and production of composite material components in aerospace and other fields. Currently, the supporting structure of conventional composite molds generally adopts a metal frame structure, and the metal frame mainly relies on welding metal processing methods to complete the connection and assembly between various components.

[0003] However, the metal support frame has significant technical drawbacks: First, the overall weight of the metal frame is large, increasing the burden of hoisting, transporting, and installing the entire composite mold; second, the large difference in the coefficients of thermal expansion between the metal and the composite material of the mold body means that during the cyclical service of mold heating and curing and cooling, the inconsistent thermal expansion and contraction deformation between the composite mold surface and the metal support frame generates additional stress inside the mold. This can lead to the dimensional accuracy of the molded composite product failing to meet theoretical design requirements, and the additional stress from repeated thermal cycles can accelerate mold damage and shorten the mold's service life. Therefore, the existing metal frame composite mold support structure suffers from problems such as heavy weight, poor thermal expansion matching, and limited mold service life, and urgently needs improvement. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a support structure for composite molds and its manufacturing method. The support structure is constructed entirely of composite material components, which can significantly reduce the weight of the entire mold, ensure that the thermal expansion performance between the support structure and the surface of the composite mold is consistent, eliminate the additional stress caused by the mismatch of thermal expansion coefficients under thermal cycling, improve the service life of the composite mold, and ensure the dimensional accuracy of the composite products.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A support structure for a composite mold includes a carbon fiber composite sheet and carbon fiber composite angle members; both the carbon fiber composite sheet and the carbon fiber composite angle members are carbon fiber composite laminates; the component has a total of 6 layers, with the layup angle sequence being 0° / 0° / 90° / 90° / 0° / 0°; the first and last layers use Guangwei brand W-3021 / GE15 / 45% carbon fiber fabric tooling prepreg, and the middle 4 layers use Guangwei brand W-7021 / GE15 / 38% carbon fiber fabric tooling prepreg; the carbon fiber composite sheet and the carbon fiber composite angle members are connected by adhesive bonding and riveting to form a composite frame, and the composite frame is connected to the composite mold surface by adhesive bonding and riveting.

[0006] According to the supporting structure of the composite mold provided by the present invention: the outer dimensions of the carbon fiber composite material sheet are CNC machined; the outer dimensions of the carbon fiber composite angle are manually machined.

[0007] This invention also proposes a method for manufacturing a support structure for a composite mold, comprising the following steps: S1. Preparation of carbon fiber composite angle material: Carbon fiber composite angle material is formed on a wooden mold using a vacuum bag process. The carbon fiber composite angle material is then manually processed to the theoretical external dimensions. S2. Preparation of carbon fiber composite material sheets: Carbon fiber composite material sheets are formed on a forming platform using a vacuum bag process. The carbon fiber composite material sheets are then CNC machined to the theoretical external dimensions. S3. Frame assembly: The processed carbon fiber composite angle pieces and carbon fiber composite plates are assembled and combined by riveting and gluing to form a composite frame; S4. Mold assembly: The composite material frame and the composite mold surface are connected as a whole by a combination of adhesive bonding and riveting to obtain the composite mold support structure.

[0008] According to the manufacturing method of the support structure of the composite mold provided by the present invention: in step S1, the surface of the wooden mold is matched with the target shape of the carbon fiber composite angle, and the vacuum bag forming process of the carbon fiber composite angle completes the heating, heat preservation curing and cooling processes according to the carbon fiber fabric tooling prepreg curing process curve.

[0009] According to the manufacturing method of the support structure of the composite mold provided by the present invention: in step S2, the forming platform is a rigid planar platform, and the vacuum bag forming process of the carbon fiber composite material plate completes the heating, heat preservation curing and cooling processes according to the carbon fiber fabric tooling prepreg curing process curve.

[0010] The manufacturing method of the support structure of the composite mold provided by the present invention includes the following steps: the bonding operation in step S3 includes: applying structural adhesive to the bonding surface of the carbon fiber composite angle and the carbon fiber composite plate, aligning and positioning them and then pre-fixing them, and completing the curing of the adhesive layer; the riveting operation includes pre-drilling assembly holes at the connection parts, and completing the riveting and fastening after the rivets are inserted into the assembly holes.

[0011] The manufacturing method of the support structure of the composite mold provided by the present invention includes the following pretreatment of the bonding surfaces of the carbon fiber composite angle and the carbon fiber composite sheet before applying adhesive: surface grinding and decontamination pretreatment.

[0012] According to the manufacturing method of the support structure of the composite mold provided by the present invention: in step S4, the connection surface between the composite material frame and the composite mold surface is first pretreated by grinding and cleaning, then coated with structural adhesive for bonding, and at the same time, riveting holes are opened for riveting.

[0013] According to the manufacturing method of the support structure of the composite mold provided by the present invention: after the support structure is assembled in step S4, the method further includes testing the shape and connection strength of the assembly of the support structure.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. The main support structure of this invention is constructed entirely of carbon fiber composite laminates to build a composite frame, replacing the traditional metal welded frame, which significantly reduces the total weight of the entire composite mold and reduces the difficulty of hoisting and transportation. 2. The support frame and the composite mold surface belong to the same major composite material system and have similar coefficients of thermal expansion. When the mold undergoes repeated thermal cycles of heating and curing and cooling, the support structure and the mold surface deform synchronously, eliminating the internal additional stress caused by the difference in thermal expansion. This not only ensures the dimensional accuracy of the composite product after molding, but also reduces mold fatigue damage and effectively extends the service life of the composite mold. 3. The components adopt a specific 6-layer layup scheme of 0° / 0° / 90° / 90° / 0° / 0°, which takes into account both the tensile and bending stiffness of the frame plane; two types of tooling prepregs from Guangwei are used for layup, with the surface layer of W-3021 / GE15 / 45% ensuring the surface quality of the components, and the middle layer of W-7021 / GE15 / 38% ensuring the overall mechanical properties; the tooling prepregs are used in combination with vacuum bag molding process, which allows for a lower curing temperature compared to autoclaves, making manufacturing easier and reducing equipment investment.

[0015] 4. CNC machining of sheet metal ensures dimensional accuracy, while corner pieces are hand-processed to fit irregular structures; a combination of adhesive and riveting is used for connection. Adhesive bonding ensures uniform load transfer on large-area bonding surfaces, while riveting provides reliable mechanical locking. The two complement each other, enhancing the overall connection strength and anti-peeling ability of the support frame, resulting in a stable and reliable structure.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the dispersion state of the composite material angle material of the present invention; Figure 2 This is a schematic diagram of the prefabricated composite material sheet of the present invention; Figure 3 This is a schematic diagram of the intermediate state of the composite material frame formed by assembling composite material corner pieces and composite material sheets according to the present invention; Figure 4 This is a schematic diagram of the overall structure of the composite material frame and composite mold surface after assembly of the present invention.

[0018] The attached diagram lists the components represented by each number as follows: 1. Composite angle material; 2. Composite sheet material; 3. Composite frame material; 4. Composite mold surface material. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0020] This invention provides a technical solution: such as Figures 1 to 4As shown in this embodiment, a support structure for a composite mold includes a carbon fiber composite plate 2 and a carbon fiber composite angle 1. Both the carbon fiber composite plate 2 and the carbon fiber composite angle 1 are carbon fiber composite laminates. The layup angle sequence is 0° / 0° / 90° / 90° / 0° / 0°. The first and sixth layers use Guangwei W-3021 / GE15 / 45% tooling prepreg, and the second to fifth layers use Guangwei W-7021 / GE15 / 38% tooling prepreg. The 0° direction is laid along the length of the part, and the 90° direction is laid along the width of the part. This layup design allows the support structure to achieve balanced mechanical properties in different directions, with better rigidity in the outer layer and better toughness in the inner layer, adapting to the stress requirements during the processing of the composite mold and avoiding deformation and cracking problems. Carbon fiber composite angle members 1 are symmetrically arranged between two adjacent carbon fiber composite sheet members 2. The three are bonded and spliced ​​together to form a closed rectangular frame structure as the composite frame 3. The composite frame 3 is bonded and fixed to the back of the composite mold surface 4, providing stable support for the composite mold surface 4. Vacuum bag curing is used for molding; the carbon fiber composite sheet members 2 are CNC milled to their theoretical dimensions; the carbon fiber composite angle members 1 are manually ground to their theoretical dimensions; after pretreatment of the joint surfaces of the carbon fiber composite sheet members 2 and the carbon fiber composite angle members 1, they are assembled using a composite connection method of adhesive bonding and riveting to form the composite frame 3; the composite frame 3 is then assembled with the composite mold surface 4 through a composite connection of adhesive bonding and riveting to form the complete composite mold assembly. Compared with traditional integral processing or single connection methods, this composite connection structure effectively reduces the molding difficulty of large-size support structures, while taking into account both connection strength and structural stability. The low weight of the composite material itself also reduces the difficulty of overall mold handling and assembly, making it suitable for the use of large-size composite molds.

[0021] The manufacturing method of the support structure of the above-mentioned composite mold includes the following steps: S1. Preparation of carbon fiber composite angle: Select a wooden mold that matches the shape of the target angle; lay the prepreg in the following order: layer 1 W-3021 / GE15 / 45%, layers 2-5 W-7021 / GE15 / 38%, layer 6 W-3021 / GE15 / 45%, layup angle 0° / 0° / 90° / 90° / 0° / 0°; after the layup is completed, seal in a vacuum bag, and follow the tooling prepreg curing process curve to perform heating, heat preservation curing, and cooling to form carbon fiber composite angle 1; demold and remove carbon fiber composite angle 1, and process it to the theoretical shape size by manual grinding.

[0022] S2. Preparation of carbon fiber composite material sheet: On a rigid planar forming platform, prepreg is laid in the following order: layer 1 W-3021 / GE15 / 45%, layers 2-5 W-7021 / GE15 / 38%, layer 6 W-3021 / GE15 / 45%, with layup angles of 0° / 0° / 90° / 90° / 0° / 0°; after the layup is completed, the sheet is sealed in a vacuum bag, and the heating, heat preservation, and cooling process is performed according to the same tooling prepreg curing process curve to obtain carbon fiber composite material sheet 2; after demolding, carbon fiber composite material sheet 2 is removed, and CNC machine tool is used to mill the carbon fiber composite material sheet 2 to the theoretical external dimensions.

[0023] S3. Frame Assembly: Grind and clean the surfaces of the carbon fiber composite angle piece 1 and carbon fiber composite plate 2 to be connected. Apply composite structural adhesive evenly to the surfaces and align and position the carbon fiber composite angle piece 1 and carbon fiber composite plate 2 for temporary pre-fixation. At the same time, pre-drill assembly holes in the connection area and insert rivets for riveting and fastening. Then, complete the curing of the adhesive layer according to the curing conditions of the structural adhesive. The carbon fiber composite angle piece 1 and carbon fiber composite plate 2 are connected to form the composite frame 3.

[0024] S4. Mold Assembly: Grind and clean the joint surfaces of the composite material frame 3 and the composite mold surface 4; apply structural adhesive to the joint surfaces; align and pre-fix the composite material frame 3 and the composite mold surface 4; open riveting holes and insert rivets to rivet and tighten; complete the curing of the structural adhesive; after assembly, conduct quality inspection to check that there are no defects such as debonding or air bubbles at the adhesive interface, that all riveting positions are not loose, and that the external dimensions are verified to meet the theoretical design, thus completing the preparation of the entire composite mold with support structure.

[0025] The composite mold support structure obtained in this embodiment has a significantly lower overall weight than a metal welded frame with equivalent stiffness. Both the support frame and the mold body are made of composite materials with matched thermal expansion properties. During repeated heating and cooling cycles, the mold will not experience additional internal stress due to thermal expansion differences, ensuring the dimensional accuracy of the molded composite parts. This also reduces mold fatigue damage and extends mold lifespan. The use of Guangwei tooling prepreg allows for lower curing temperatures, and the vacuum bag process is more convenient than autoclave manufacturing. The adhesive-riveting composite connection method balances the uniform load transfer of large-area adhesive bonding with the reliability of riveting mechanical locking. The overall stiffness and connection reliability of the support structure meet the operating conditions of the composite mold. Compared to traditional metal support structures, this support structure does not require large processing equipment, lowering the equipment investment threshold, shortening the production cycle, and reducing manufacturing costs. Furthermore, the composite material itself has excellent corrosion resistance, eliminating the need for regular anti-corrosion maintenance like metal structures, reducing the maintenance costs throughout the mold's lifespan, and making it more suitable for the use of large-size composite molds.

[0026] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or equivalent changes made by those skilled in the art without departing from the scope of the present invention, using the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, the present invention possesses prominent substantive features and significant progress, is reasonable in content, and the description is complete and possesses sufficient inventiveness.

Claims

1. A support structure for a composite mold, characterized in that, It includes carbon fiber composite material sheet (2) and carbon fiber composite material corner piece (1); the carbon fiber composite material sheet (2) and the carbon fiber composite material corner piece (1) are both carbon fiber composite material laminates. The carbon fiber composite material sheet (2) and the carbon fiber composite material corner piece (1) are connected and combined by adhesive bonding and riveting to form a composite material frame (3). The composite material frame (3) has a composite material mold surface (4) by adhesive bonding and riveting.

2. The support structure for a composite mold according to claim 1, characterized in that, The outer dimensions of the carbon fiber composite material sheet (2) are CNC machined; the outer dimensions of the carbon fiber composite material angle (1) are manually machined.

3. The support structure for a composite mold according to claim 1, characterized in that, The carbon fiber composite material sheet (2) and carbon fiber composite material angle (1) are both laid up with 6 layers, and the layup angle sequence is 0°, 0°, 90°, 90°, 0°, 0°.

4. A method for manufacturing a support structure for a composite mold according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of carbon fiber composite corner piece (1): Carbon fiber composite corner piece (1) is formed on a wooden mold using a vacuum bag process. The carbon fiber composite corner piece (1) is then manually processed to the theoretical external dimensions. S2. Preparation of carbon fiber composite material plate (2): Carbon fiber composite material plate (2) is formed on the forming platform using vacuum bag process. The carbon fiber composite material plate (2) is then CNC machined to the theoretical external dimensions. S3, Frame assembly: The processed carbon fiber composite angle (1) and carbon fiber composite plate (2) are assembled by riveting and gluing to form a composite frame (3). S4. Mold assembly: The composite material frame (3) and the composite mold surface (4) are connected as a whole by a combination of adhesive bonding and riveting to obtain the composite mold support structure.

5. The manufacturing method of the support structure of a composite mold according to claim 4, characterized in that, In step S1, the shape of the wooden mold matches the target shape of the carbon fiber composite angle (1). The vacuum bag forming process of the carbon fiber composite angle (1) completes the heating, heat preservation curing and cooling processes according to the curing process curve of the tooling prepreg.

6. The manufacturing method of the support structure of a composite mold according to claim 5, characterized in that, In step S2, the forming platform is a rigid planar platform, and the vacuum bag forming process of the carbon fiber composite material sheet (2) completes the heating, heat preservation curing and cooling processes according to the curing process curve of the tooling prepreg.

7. The manufacturing method of the support structure of a composite mold according to claim 6, characterized in that, The adhesive bonding operation in step S3 includes: applying structural adhesive to the bonding surfaces of the carbon fiber composite angle (1) and the carbon fiber composite plate (2), aligning and positioning them, pre-fixing them, and completing the curing of the adhesive layer; the riveting operation includes pre-drilling assembly holes at the connection points, inserting rivets into the assembly holes, and completing the riveting and fastening.

8. The manufacturing method of the support structure of a composite mold according to claim 7, characterized in that, The treatment of the bonding surfaces of the carbon fiber composite angle (1) and the carbon fiber composite sheet (2) before applying adhesive includes: surface grinding and decontamination pretreatment.

9. The method for manufacturing a support structure for a composite mold according to claim 8, characterized in that, In step S4, the connection surfaces of the composite material frame (3) and the composite material mold surface (4) are first pretreated by grinding and cleaning, and then structural adhesive is applied for bonding. At the same time, riveting holes are opened to implement riveting.

10. A method for manufacturing a support structure for a composite mold according to claim 9, characterized in that, After the support structure is assembled in step S4, the shape and connection strength of the assembled components of the support structure are also tested.

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