A Method for Designing Molding Dies for Aerospace Composite Parts Based on 3D Printing

Abstract

This invention discloses a method for designing a molding die structure for aerospace composite material parts based on 3D printing. The method includes: S1. Extracting the molding surface of the aerospace composite material part; S2. Creating a model entity of the molding die on a printing reference surface based on the molding surface; S3. Designing the printing angle of the model entity; S4. Filling the gap between the model entity with the designed printing angle and the printing reference surface; S5. Compensating for the size of the filled model entity based on the thermal expansion coefficient of the die material. This invention can effectively shorten the die manufacturing cycle and reduce die weight and manufacturing costs.

Description

Technical Field

[0001] This invention belongs to the field of mold structure design technology in the field of work-additive manufacturing technology, specifically involving a method for designing a molding mold structure for aerospace composite material parts based on 3D printing. Background Technology

[0002] Composite material parts, with their advantages of high strength and low weight, are widely used in various aircraft structures. These parts require thermosetting manufacturing using specialized molding dies. Patents CN117754779A (a composite wing skin lattice molding die and its manufacturing method), CN107866987A (an aircraft fairing mold and its usage method), and CN104339495A (a template frame type molding die and frame connection method) disclose design methods for molding dies for composite material parts made of Invaganza, carbon steel, aluminum alloy, and other metal materials. These structural molds require manufacturing through rolling, welding, and machining. Patents CN116442517A (fused deposition modeling method, equipment, storage medium, and fused deposition modeling components) and CN117584443A (a three-dimensional fused deposition modeling method for complex models) disclose innovations in component molding methods, equipment, materials, and storage media related to fused deposition modeling 3D printing technology. However, none of the aforementioned inventions address the structural design of molding dies for thermoplastic polymer aerospace composite parts based on fused deposition modeling (FDM) 3D printing technology. Metal structure molding dies suffer from drawbacks such as long manufacturing cycles, large die weight, high production costs, and unstable airtightness. Furthermore, their designed structures cannot be directly used for 3D printing, failing to guarantee printing stability and safety. Summary of the Invention

[0003] The purpose of this invention is to provide a method for designing molding dies for aerospace composite parts based on 3D printing. This invention can effectively shorten the die manufacturing cycle and reduce die weight and manufacturing costs.

[0004] The technical solution of this invention is: a method for designing molding die structures for aerospace composite material parts based on 3D printing, comprising the following steps:

[0005] S1. Extract the molding surface of aerospace composite material parts;

[0006] S2. Create a model entity of the molding die on the printing reference surface based on the molding surface;

[0007] S3. Design the printing angle of the model entity;

[0008] S4. Fill the gap between the model entity after designing the printing angle and the printing reference plane;

[0009] S5. Compensate for the size of the filled model entity based on the thermal expansion coefficient of the mold material.

[0010] The aforementioned method for designing molding die structures for aerospace composite parts based on 3D printing also includes:

[0011] S6. Based on strength analysis, the model entity is filled using the crystal structure.

[0012] The aforementioned method for designing molding die structures for aerospace composite parts based on 3D printing also includes:

[0013] S7. Optimize printing parameters and printing path through simulation using 3D printing slicing software.

[0014] In the aforementioned design method for molding die structure of aerospace composite parts based on 3D printing, in step S1, after extracting the molding surface, the edge of the molding surface is extended.

[0015] In the aforementioned design method for molding die structure of aerospace composite parts based on 3D printing, in step S1, after extracting the molding surface, the empty parts on the molding surface are filled so that the entire molding surface forms a complete closed curved surface.

[0016] In the aforementioned method for designing molding die structures for aerospace composite parts based on 3D printing, the method for creating the model entity in step S2 is as follows:

[0017] S21. Select printing direction: Select the direction with the least change in the curvature of the model solid surface as the printing direction;

[0018] S22. Create a printing reference plane: Select a plane perpendicular to the printing direction as the reference plane for printing the model entity;

[0019] S23. Create solid: Create a rectangular solid on the reference plane, and then cut it through the template surface to form a solid model.

[0020] In the aforementioned method for designing molding die structures for aerospace composite parts based on 3D printing, step S3 is as follows:

[0021] S31. Identify the overhang angle: Find the point of maximum curvature of the surface in the solid model, draw the tangent at the point of maximum curvature, and the angle between the tangent and the perpendicular line of the reference plane is the overhang angle;

[0022] S32. Adjust the printing angle to set the maximum overhang angle to <45°.

[0023] In the aforementioned design method for molding die structure of aerospace composite parts based on 3D printing, in step S5, the die material is PPS-CF, with a coefficient of thermal expansion of 99.5% at 180℃.

[0024] The advantages of this invention are:

[0025] 1. The present invention uses a mixture of thermoplastic polymer and short-cut carbon fiber and manufactures a molding die using fused deposition modeling (FDM) technology. This effectively shortens the mold manufacturing cycle, reduces mold weight and manufacturing cost, and ensures the airtightness of the molding process.

[0026] 2. This invention provides a method for designing mold structures for aerospace composite parts based on fused deposition modeling (FDM) technology and using thermoplastic polymer materials as the main material. This method improves the design efficiency of such molds and enhances the stability and safety of the 3D printing and finishing processes.

[0027] 3. The design time for the molding die of aerospace composite material parts using the present invention is 2 hours, while the design time for the mold of the traditional template frame structure of the same aircraft product parts is 10 hours. The design time is reduced by 80%, which effectively improves the design efficiency of the molding die of aerospace composite material parts and improves the stability and safety of the 3D printing and reprocessing process.

[0028] 4. This invention has been applied to the structural design of molding dies for aerospace composite parts based on fused deposition modeling 3D printing technology and using thermoplastic polymer materials as the main material. It provides a method for the structural design of such dies and further promotes technological innovation in the field of aerospace composite parts molding and manufacturing. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the film surface extraction;

[0030] Figure 2 This is a schematic diagram of surface extension and closure;

[0031] Figure 3 This is a diagram illustrating the selection of the printing direction;

[0032] Figure 4 This is a preliminary schematic diagram of the solid cutting process;

[0033] Figure 5 This is a schematic diagram for overhang angle recognition;

[0034] Figure 6 This is a diagram showing the overhang angle;

[0035] Figure 7 This is a schematic diagram of the adjusted overhang angle;

[0036] Figure 8 This is a schematic diagram of solid filling;

[0037] Figure 9 It is a schematic diagram of the crystal lattice;

[0038] Figure 10 This is a simulation path diagram. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0041] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Example 1. A method for designing molding die structures for aerospace composite parts based on 3D printing, see [link to example]. Figures 1-10 Based on the key technical aspects of fused deposition modeling (FDM) 3D printing and the application advantages of thermoplastic polymer materials, a professional structural design method for molding dies of aerospace composite parts is developed. This method includes steps such as part model processing, initial structural design, printing angle and direction adjustment, lattice structure setting, and simulation, as detailed below:

[0043] 1. Part Model Processing

[0044] 1.1 Extracting the Film-Mounting Surface: The film-mounting surface of an aerospace composite part refers to the surface in contact with the mold. First, the specified film-mounting surface is extracted from the aerospace composite part model using modeling software, serving as the data basis for modeling. See [link to relevant documentation]. Figure 1 .

[0045] 1.2 Surface Extension: Extend the surface edge by 300mm using modeling software. See [link / reference] Figure 2 .

[0046] 1.3 Surface Closure: Using modeling software to fill holes, slots, and other areas on a part to form a closed surface. See [link to modeling software]. Figure 2 .

[0047] 2. Create model entities

[0048] 2.1 Select Printing Direction: Choose the direction with the least change in the curvature of the product surface as the printing direction. See [link to relevant documentation]. Figure 3 .

[0049] 2.2 Creating a Printing Reference Plane: Select a plane perpendicular to the printing direction as the reference plane for printing the mold. See [link to documentation]. Figure 4 .

[0050] 2.3 Creating a Solid: Create a rectangular solid on the reference plane, and after cutting it through the film-coating surface, form a preliminary solid model. See [link to documentation]. Figure 4 .

[0051] 3. Printing angle and height

[0052] 3.1 Identifying Overhang Angles: Since fused deposition modeling (FDM) 3D printing involves the layering of molten material along the outline of the model, when there are discontinuous curvatures on the part's surface, the contact area between subsequent layers decreases, resulting in overhang angles in the printed structure. The overhang angle is calculated as the angle between the tangent to the vertical section of the model and the perpendicular to the ground. (See [link to relevant documentation]). Figure 5 When the overhang angle is greater than 45°, the printed part will deform or sag under the influence of the material's gravity, potentially leading to printing failure. See also... Figure 6 The maximum overhang angle of the preliminary solid model is 86°.

[0053] 3.2 Adjusting the Printing Angle: The overhang angle is reduced by adjusting the printing angle of the solid model. After adjusting the placement angle of the solid model, the maximum overhang angle is adjusted to <45°. See [link / reference]. Figure 7 .

[0054] 4. Solid Filling

[0055] The adjusted solid model had a gap with the reference plane, preventing the printing process from starting normally. Therefore, the gap was completely filled and the excess parts were trimmed. See [link / reference]. Figure 8 .

[0056] 5. Mold thermal expansion compensation

[0057] Aerospace composite material parts are cured and molded in an autoclave at 180°C. Since the material selected for the mold is PPS-CF, which has a coefficient of thermal expansion of 99.5% at 180°C, the solid model needs to be scaled down to 99.5% based on this ratio.

[0058] 6. Lattice filling

[0059] To reduce mold printing costs and weight, the mold underwent lightweighting treatment and increased lattice filling. See [link / reference]. Figure 9 .

[0060] 7. Simulation optimization

[0061] By setting the layer height to 3mm, the linewidth to 20mm, and the layer time to 90s in the 3D printing slicing software, a printing time of 9.8 hours and a printing weight of 255kg were obtained. A printing path was also generated. (See attached image.) Figure 10 The printing path was simulated and analyzed to verify the correctness of the mold structure, and the design of the printing mold structure model was completed.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for designing molding die structures for aerospace composite material parts based on 3D printing, characterized in that, Includes the following steps: S1. Extract the molding surface of the aerospace composite material part; after extracting the molding surface, fill the voids on the molding surface to make the entire molding surface form a complete closed curved surface; S2. Create a model entity of the molding die on the printing reference plane based on the molding surface: S21. Select printing direction: Select the direction with the least change in the curvature of the model solid surface as the printing direction; S22. Create a printing reference plane: Select a plane perpendicular to the printing direction as the reference plane for printing the model entity; S23. Create solid: Create a rectangular solid on the reference plane, and cut it through the template surface to form a solid model; S3. Design the printing angle of the model entity: S31. Identify the overhang angle: Find the point of maximum curvature of the surface in the solid model, draw the tangent at the point of maximum curvature, and the angle between the tangent and the perpendicular line of the reference plane is the overhang angle; S32. Adjust the printing angle to set the maximum overhang angle to <45°; S4. Fill the gap between the model entity after designing the printing angle and the printing reference plane; S5. Compensate for the size of the filled model entity based on the thermal expansion coefficient of the mold material.

2. The method for designing molding die structure for aerospace composite material parts based on 3D printing according to claim 1, characterized in that, Also includes: S6. Based on strength analysis, the model entity is filled using the crystal structure.

3. The method for designing molding die structure for aerospace composite material parts based on 3D printing according to claim 2, characterized in that, Also includes: S7. Optimize printing parameters and printing path through simulation using 3D printing slicing software.

4. The method for designing molding die structure for aerospace composite parts based on 3D printing according to claim 1, characterized in that, In step S1, after extracting the template surface, the edges of the template surface are extended.

5. The method for designing molding die structure for aerospace composite parts based on 3D printing according to claim 1, characterized in that, In step S5, the mold material is PPS-CF, which has a coefficient of thermal expansion of 99.5% at 180°C.

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