Structural design method of aviation composite material part forming mold based on 3D printing

Abstract

The invention discloses an aviation composite part forming mold structure design method based on 3D printing. The method comprises the following steps: S1, extracting an aeronautical composite part die- S2, creating a model entity of the forming mold on the printing reference surface based on the mold pasting surface; s3, designing a printing angle of the model entity; s4, filling a gap between the model entity and the printing reference surface after the printing angle is designed; and S5, compensating the size of the filled model entity based on the thermal expansion coefficient of the mold material. The die manufacturing period can be effectively shortened, and the die weight and the manufacturing cost are reduced.

Description

Technical Field

[0001] The present invention belongs to the mold structure design technology in the field of operation-additive manufacturing technology, and specifically relates to a method for designing a mold structure for aviation composite parts based on 3D printing. Background Art

[0002] Composite parts are widely used in various aircraft structures due to their high strength and low weight. Such parts need to be manufactured by thermal curing of special molding molds. Patents CN117754779A, a composite wing skin lattice molding mold and its manufacturing method, CN107866987A, an aircraft fairing mold and its use method, CN104339495A, a template frame molding mold body and frame connection method, etc., disclose the design method of composite parts molding molds made of metal materials such as Yinwagang, carbon steel, and aluminum alloy. Such structural molds need to be manufactured by roller forming, welding, machining, etc. Patents CN116442517A, fused deposition molding methods, equipment, storage media, and fused deposition molding components, CN117584443A, a three-dimensional fused deposition molding method for complex models, etc. disclose innovations in component molding methods, applied equipment, materials, storage media, etc. related to fused deposition 3D printing technology. However, none of the above inventions involve the structural design of thermoplastic polymer aviation composite parts molding molds based on fused deposition 3D printing technology. Metal structure molding molds have shortcomings such as long manufacturing cycle, heavy mold weight, high production cost, unstable air tightness, etc. At the same time, the design structure cannot be directly used for 3D printing, and the stability and safety of printing cannot be guaranteed. Summary of the invention

[0003] The purpose of the present invention is to provide a method for designing a mold structure for aviation composite parts based on 3D printing. The present invention can effectively shorten the mold manufacturing cycle, reduce the mold weight and manufacturing cost.

[0004] The technical solution of the present invention is: a method for designing a mold structure for aviation composite parts based on 3D printing, comprising the following steps:

[0005] S1. Extract the die-bonding surface of aviation composite parts;

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

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

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

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

[0010] The aforementioned 3D printing-based aviation composite parts forming mold structure design method also includes:

[0011] S6. Based on the strength analysis, the model entity is filled with a lattice structure.

[0012] The aforementioned 3D printing-based aviation composite parts forming mold structure design method also includes:

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

[0014] In the aforementioned 3D printing-based aviation composite material part forming mold structure design method, in step S1, after the mold attachment surface is extracted, the edge of the mold attachment surface is extended.

[0015] In the aforementioned 3D printing-based aviation composite parts forming mold structure design method, in step S1, after the mold surface is extracted, the hollow parts on the mold surface are filled so that the entire mold surface forms a complete closed curved surface.

[0016] In the aforementioned 3D printing-based aviation composite material part forming mold structure design method, in step S2, the method for creating the model entity is as follows:

[0017] S21. Select printing direction: select the direction with the smallest curvature change 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 entity: Create a rectangular entity on the reference plane and form a solid model after cutting through the mold surface.

[0020] In the aforementioned 3D printing-based aviation composite material part forming mold structure design method, step S3 is specifically as follows:

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

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

[0023] In the aforementioned method for designing a mold structure for aviation composite parts based on 3D printing, in step S5, the mold material is PPS-CF, and the thermal expansion coefficient at 180° C. is 99.5%.

[0024] The advantages of the present invention are:

[0025] 1. The present invention adopts a thermoplastic polymer and chopped carbon fiber mixed material and manufactures a molding mold through fused deposition 3D printing technology, which can effectively shorten the mold manufacturing cycle, reduce the mold weight and manufacturing cost, and ensure molding air tightness.

[0026] 2. The present invention provides a structural design method for aviation composite parts molding molds using thermoplastic polymer materials as the main material based on fused deposition 3D printing technology, which improves the design efficiency of such molds and the stability and safety of 3D printing and repair processes.

[0027] 3. The design time of the aviation composite parts forming mold designed by the present invention is 2 hours, while the design time of the mold of the traditional template frame structure of the aircraft product parts is 10 hours, which reduces the design time by 80%, effectively improving the design efficiency of the aviation composite parts forming mold, and improving the stability and safety of the 3D printing and repair processing process.

[0028] 4. The present invention has been applied to the structural design of aviation composite parts molding molds based on fused deposition 3D printing technology with thermoplastic polymer materials as the main material, providing a method for the structural design of such molds and further promoting technological innovation in the field of aviation composite parts molding and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0031] Figure 3 It is a schematic diagram for selecting the printing direction;

[0032] Figure 4 It is a preliminary solid cutting diagram;

[0033] Figure 5 is a schematic diagram of overhang angle identification;

[0034] Figure 6 is a schematic diagram of the overhang angle;

[0035] Figure 7 is a schematic diagram of the overhang angle after adjustment;

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

[0037] Fig. 9 is a schematic diagram of the lattice;

[0038] Fig.10 It is a schematic diagram of the simulation path. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 making creative work are within the scope of protection of the present invention.

[0040] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] Example 1. A method for designing a mold structure for aviation composite parts based on 3D printing, see Figure 1-Figure 10 According to the technical points of fused deposition 3D printing and the application advantages of thermoplastic polymer materials, a professional structural design method for aviation composite parts forming molds is formed, including part model processing, initial structure design, printing angle and direction adjustment, lattice structure setting and simulation, etc. The specific steps are as follows:

[0043] 1. Part model processing

[0044] 1.1 Extract the film surface: The die surface of the aviation composite part refers to the surface that the mold contacts. First, use the modeling software to extract the film surface specified in the aviation composite part model as the data basis for modeling. Figure 1 .

[0045] 1.2 Surface extension: Use modeling software to extend the surface edge by 300mm, see Figure 2 .

[0046] 1.3 Surface Closure: Use modeling software to fill holes, slots, etc. on parts to form a closed surface, see Figure 2 .

[0047] 2. Create model entities

[0048] 2.1 Select the printing direction: Select the direction with the smallest change in product surface curvature as the printing direction, see Figure 3 .

[0049] 2.2 Create a printing reference plane: Select a plane perpendicular to the printing direction as the reference plane for the model printing. Figure 4 .

[0050] 2.3 Create entity: Create a rectangular entity on the reference plane, and form a preliminary entity model after cutting the film surface. Figure 4 .

[0051] 3. Printing angle and height

[0052] 3.1 Identify the overhang angle: Since the process principle of fused deposition 3D printing is to deposit molten materials layer by layer along the contour of the model, when there is discontinuous curvature on the part surface, the contact area between the next layer and the previous layer will decrease, and the printed structure will have an overhang angle. The calculation method of the overhang angle is the angle between the tangent line of the vertical section of the model and the perpendicular line to the ground, see Figure 5 When the overhang angle is greater than 45°, the printed part will deform or sag under the weight of the material, and may even cause printing failure. Figure 6 , the maximum overhang angle of the preliminary solid model is 86°.

[0053] 3.2 Adjust the printing angle: The method to reduce the overhang angle is to adjust the physical printing angle. After adjusting the placement angle of the physical model, the maximum overhang angle is adjusted to <45°, see Figure 7 .

[0054] 4. Solid Fill

[0055] After adjusting the angle, there is a gap between the solid model and the reference surface, and the printing work cannot be started normally. Therefore, the gap is completely filled and the excess part is trimmed. Figure 8 .

[0056] 5. Mold thermal expansion compensation

[0057] Aviation composite parts are formed by curing in an autoclave at 180°C. Since the mold is made of PPS-CF material, which has a thermal expansion coefficient of 99.5% at 180°C, the solid model needs to be scaled down according to this ratio, with a reduction ratio of 99.5%.

[0058] 6. Lattice filling

[0059] In order to reduce the cost and weight of mold printing, the mold was lightweighted and lattice filling was increased. Fig. 9 .

[0060] 7. Simulation optimization

[0061] By setting the printing layer height to 3mm, the printing line width to 20mm, and the single layer time to 90s in the 3D printing slice software, the printing time is 9.8 hours and the printing weight is 255kg. At the same time, the printing path is generated. Fig.10 . Perform simulation analysis on the printing path to verify that the mold structure is correct and complete the design of the printing mold structure model.

[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 technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for designing a mold structure for aviation composite parts based on 3D printing, characterized in that: The steps include: S1. Extract the die-bonding surface of aviation composite parts; S2. Creating a model entity of the molding mold on the printing reference surface based on the mold surface; S3. Design the printing angle of the model entity; S4. Fill the gap between the model entity after the designed printing angle and the printing reference surface; S5. Compensate the size of the filled model entity based on the thermal expansion coefficient of the mold material.

2. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: Also includes: S6. Based on the strength analysis, the model entity is filled with a lattice structure.

3. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 2, characterized in that: Also includes: S7. Optimize printing parameters and printing paths through 3D printing slicing software simulation.

4. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: In step S1, after the die attaching surface is extracted, the edge of the die attaching surface is extended.

5. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: In step S1, after the die-mounting surface is extracted, the hollow parts on the die-mounting surface are filled so that the entire die-mounting surface forms a complete closed curved surface.

6. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: In step S2, the method for creating the model entity is as follows: S21. Select printing direction: select the direction with the smallest curvature change 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 entity: Create a rectangular entity on the reference plane and form a solid model after cutting through the mold surface.

7. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: Step S3 is as follows: S31. Identify the overhang angle: find the maximum curvature of the surface in the solid model, draw a tangent at the maximum curvature, and the angle between the tangent and the perpendicular to the reference plane is the overhang angle; S32. Adjust the printing angle and adjust the maximum overhang angle to <45°.

8. The method for designing a mold structure for aviation composite parts based on 3D printing according to claim 1, characterized in that: In step S5, the mold material is PPS-CF, and the thermal expansion coefficient at 180° C. is 99.5%.

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