A high-efficiency and high-quality processing method for PEEK-based composite grids

Abstract

The present invention relates to the technical field of 3D printing molding of composite materials, and discloses a method for efficiently and high-quality processing of PEEK-based composite material grids. The method comprehensively considers the requirements of 3D printing process and CNC machining process, processing quality and stability, processing efficiency, etc. to design a process model of multiple combinations, completes 3D printing of parts based on the process model, and then completes batch processing of parts according to the process flow of "3D printing→heat treatment→CNC machining", wherein CNC machining should follow the corresponding processing sequence, thereby achieving efficient and high-quality processing of grid parts.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material 3D printing molding, and in particular to a method for efficiently and high-quality processing of a PEEK-based composite material grid. Background Art

[0002] Composite materials, with their high strength, lightweight, and multifunctionality, are widely used in aircraft, and their usage has become a key indicator of aircraft advancement. Advanced composite grid structures, combining the advantages of new material technologies and novel structural designs, have attracted widespread attention for their strong designability and diverse performance characteristics, leading to a surge in research and application both domestically and internationally.

[0003] Currently, advanced composite grid structures are primarily used in aircraft fuselages, tail wings, leading edges, and other structural or functional components, expanding and enhancing component functions and performance, while also reducing weight. However, due to limitations in existing composite manufacturing technology, grid structures currently primarily take the form of regular structures such as flat plates and cylinders, and are relatively large in size, severely limiting the scope of application for advanced composite grid structures. The combination of high-performance thermoplastic composites such as carbon fiber-reinforced polyetheretherketone (CEEK) with 3D printing technology offers new avenues for the application of grid structure components. Some grid structures designed to meet aircraft weight reduction, heat dissipation, and other functional and assembly requirements exhibit complex features such as variable curvature, small grid cell size (5.2mm side length, 1mm wall thickness), and variable thickness. However, current component manufacturing processes suffer from poor quality, heavy manual labor, and poor component precision, making it difficult to meet technical requirements. Summary of the Invention

[0004] In order to solve the problems and shortcomings existing in the above-mentioned prior art, the present invention proposes an efficient and high-quality processing method for PEEK-based composite material grids, which is particularly suitable for the manufacturing and processing of parts with complex features such as complex surfaces, small grid cell size, and uneven thickness, and can realize efficient and high-quality molding and manufacturing of parts.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0006] A method for efficiently and high-quality processing of PEEK-based composite grilles is described. This method uses a process model to complete 3D printing of parts, then follows a process flow of "3D printing → heat treatment → CNC machining" to complete batch processing of parts. The CNC machining process follows the corresponding processing sequence, thereby achieving efficient and high-quality processing of grille parts. Specifically, the method includes the following steps:

[0007] Step S1. 3D printing plan design

[0008] Step S1.1. Assuming the original part process digital model is Model A, add a 2% margin to the perimeter of Model A, and a 1mm margin in the thickness direction and on the bottom. Then, add two positioning tabs of different structural shapes (different shapes for differentiation) on both sides of Model A, and add a φ4.9 mm (or φ5.2 mm) pin hole on each tab. Finally, generate a new process model A1.

[0009] Step S1.2. Select the lowest three points on process model A1 to establish plane P. The distance between the highest point on process model A1 and plane P is the minimum thickness δ that can wrap process model A1. The normal (upward) of the plane is defined as the 3D printing growth direction of the part (i.e., the +Z direction). Therefore, plane P is offset along the +Z direction by a distance δ" to generate plane P1.

[0010] Step S1.3. Offset plane P1 along the +Z direction by a distance δ″′ to generate plane P1″. Offset plane P along the -Z direction by a distance δ″′ to generate plane P″. Stretch the grille area along the grille opening (i.e., extend the grille up and down along the grille opening). The upper and lower boundaries of the stretching are planes P1″ and P″, respectively. Finally, generate process model A2.

[0011] Step S2. Group processing plan design

[0012] Step S2.1. Array the process model A2 in the +Z direction, with an array distance of δ"+5mm and an array quantity a < part width / (δ"+5), and finally generate the process model A3;

[0013] Step S3. CNC machining scheme design

[0014] Step S3.1. Extract the upper surface of process model A1 to generate surface S. Rotate and translate surface S so that its contour matches that of process model A1 as closely as possible. Surface S is then translated in the -Z direction with a minimum movement distance of 5 mm, typically no more than 10 mm. Surface S is then thickened in the -Z direction by 2 mm to generate the clamping mold process model B.

[0015] Step S3.2. Design planar baseplate process model C: Create a plane below process model B. Project the dimensions of process model A3 and process model B onto this plane. Deflect the maximum projected dimensions outward by a distance δ″′ to construct planar baseplate process model C. The offset δ″′ is typically 50-80 mm. Process model C is typically 2-5 mm thick and is positioned below process model B with a minimum spacing of 2 mm. Add a φ3 mm machined locating hole on the baseplate outside the projected area.

[0016] Step S4. Auxiliary structure design and slicing parameter setting

[0017] Auxiliary structures of grouped parts are directly generated by slicing software

[0018] Step S4.1. Auxiliary support design: The support form is full support, the support shape is a triangular grid, the spacing is 1 / 2 the length of a single grid side, and the wiring is once;

[0019] Step S4.2. Slicing Parameter Setting: Simultaneously import process models C, B, and A3 into the slicing software and assemble them in their original positions. Before importing process models B and A3 into the slicing software, all pin holes on them must be sealed to prevent them from being printed during 3D printing. Slicing parameters are then set based on the part structure. Finally, the three process models will generate a 3D printing code, which can then be 3D printed to form a complete component.

[0020] Step S5. Processing procedure design

[0021] Step S5.1. Based on process model C, process model B, and process model A3, 3D print the entire component according to the printing code generated in step S4;

[0022] Step S5.2. Remove the entire assembly from the 3D printing equipment and place it in an oven for heat treatment at a temperature of 280-300°C, a heating rate of 2°C / min, and a holding time of 120 min.

[0023] Step S5.3. After heat treatment, place the part on the CNC machine for clamping and perform CNC machining according to the machining code compiled in the programmed CNC machining sequence. During machining, strictly follow the following sequence (assuming the parts are numbered D1 to Dn from bottom to top):

[0024] Step S5.3.1. CNC machine the upper surface of Dn and drill the pin holes on Dn;

[0025] Step S5.3.2. Cutting the part Dn from the overall assembly by means of a heating wire;

[0026] Step S5.3.3. CNC machine the upper surface of Dn-1 and drill the pin holes on Dn-1;

[0027] Step S5.3.4. Cutting part Dn-1 from the overall assembly using a heating wire;

[0028] Step S5.3.5. Repeat the above process until part D1 is cut from the entire assembly;

[0029] Step S5.3.6. Add the clamping die and drill the pin holes on the clamping die using the CNC machine;

[0030] Step S5.3.7. Place D1 to Dn on the clamping mold for positioning and fixing respectively, and CNC machine the other side of the part. After the surface processing is completed, the positioning ears are milled off to obtain the final shape of the part.

[0031] In the entire machining process, process model C is the base plate, and its main function is to position the entire assembly on the machine tool during CNC machining. It is not a part and does not require processing.

[0032] Furthermore, in the present invention, the offset distance δ" of plane P along the +Z direction is an integer slightly larger than δ, for example, 0-1 mm; the offset distance δ′" between plane P1 and plane P is generally 2.5 mm. If it is lower than this value, it will be difficult to separate them after subsequent group forming. If it is greater than this value, the printing time and printing risk will be increased.

[0033] Furthermore, in the present invention, when setting the slicing parameters according to the part structure, the slicing parameters of the process model C need to be set separately, including: designing the process model C to have no top and bottom surfaces (the base plate has no upper surface and lower surface after printing), the outer wall thickness is 2mm, the internal filling pattern is a triangle, the spacing is 5mm, and the wiring is once.

[0034] Beneficial effects of the present invention:

[0035] (1) The present invention does not require manual polishing and other workloads, and the processed parts are of good quality and high precision. In addition, the invention can realize the combined manufacturing of multiple parts, which has higher processing efficiency.

[0036] (2) The present invention does not require additional manufacturing of clamping molds, has low manufacturing costs and does not require the use of tooling warehouses, thus reducing tooling turnover and shortening the manufacturing cycle.

[0037] (3) The present invention can eliminate the influence of part deformation during the printing process on the manufacturing accuracy and quality of parts by designing a reasonable process margin, and has a high fault tolerance rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which:

[0039] Figure 1-Figure 3 This is a schematic diagram of a typical composite material grid component of the present invention;

[0040] Figure 4 Schematic diagram of process model A1 of the present invention;

[0041] Figure 5 This is a schematic diagram of the minimum thickness and Z direction of the process model A1 of the present invention;

[0042] Figure 6 This is a schematic diagram of the design process of process model B of the present invention;

[0043] Figure 7 This is a three-dimensional view of the process model A2 of the present invention;

[0044] Figure 8 This is a front view of the process model A2 of the present invention;

[0045] Figure 9 This is an enlarged view of the grid in the stretching direction of the present invention;

[0046] Figure 10 This is a schematic diagram of 3D printing of parts of the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will further illustrate the technical solutions for achieving the purpose of the present invention through several specific embodiments. It should be noted that the technical solutions claimed for protection by the present invention include but are not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] Currently, advanced composite grid structures are primarily used in aircraft fuselages, tail wings, leading edges, and other structural or functional components, expanding and enhancing component functions and performance, while also reducing weight. However, due to limitations in existing composite manufacturing technology, grid structures currently primarily take the form of regular structures such as flat plates and cylinders, and are relatively large in size, severely limiting the scope of application for advanced composite grid structures. The combination of high-performance thermoplastic composites such as carbon fiber-reinforced polyetheretherketone (CEEK) with 3D printing technology offers new avenues for the application of grid structure components. Some grid structures designed to meet aircraft weight reduction, heat dissipation, and other functional and assembly requirements exhibit complex features such as variable curvature, small grid cell size (5.2mm side length, 1mm wall thickness), and variable thickness. However, current component manufacturing processes suffer from poor quality, heavy manual labor, and poor component precision, making it difficult to meet technical requirements.

[0049] Based on this, an embodiment of the present invention proposes an efficient and high-quality processing method for PEEK-based composite material grids, which is particularly suitable for the manufacturing and processing of complex feature parts with complex surfaces, small grid cell size, uneven thickness, etc., and can realize efficient and high-quality molding and manufacturing of parts.

[0050] This embodiment discloses a method for processing a PEEK-based composite material grid with high efficiency and high quality. Figure 1-Figure 3 ( Figure 1 For top view, Figure 2 is a side view, Figure 3(a cross-sectional view) is a schematic diagram of a typical grid-type composite part of the present invention; the surface is complex, the thickness is variable (there are three thicknesses of 1.40mm, 2.05mm, and 4.05mm), the grid cell side length is 5.2mm, and the wall thickness is 1mm. The four sides of the part are about 175mm long, so a 3.5mm process allowance is added to the periphery (175mm×2%), and a 1mm allowance is added to the upper and lower surfaces. Then, two positioning ears are added to the model in an offset manner (one of which is a square ear and the other is a round ear to distinguish them), and a φ4.9mm (or φ5.2mm) pin hole is added to each ear. Finally, the process model A1 is generated. The model diagram is attached to the instruction manual. Figure 4 . Further, refer to the appendix of the specification Figure 5 , select the three lowest points on the process model A1 (relatively lowest, not absolutely accurate, and the three points cannot be on a straight line, they should be as dispersed as possible) to establish plane P, set the normal direction of plane P (upward) as the 3D printing growth direction of the part (i.e. +Z direction), after measurement, the distance δ between the highest point on the part and plane P is about 9.912mm, round δ" = 10mm and record it, and offset plane P by 10mm in the +Z direction to generate plane P1. For further information, please refer to Figure 7-Figure 9 , offset the plane P1 of the process model A1 by 2.5mm in the +Z direction to generate plane P1", offset the plane P by 2.5mm in the -Z direction to generate plane P", stretch the grille area in the direction of the grille opening, when stretching, the upward extended boundary (upper boundary) is plane P1", and the downward extended boundary (lower boundary) is P", and finally generate the process model A2.

[0051] Refer to the instruction manual Figure 10 , array process A2 in the +Z direction, with an array distance of 15 mm (array distance is δ"+5 mm), array quantity a<part width / (δ"+5)=175 / 15=11.7, so the array quantity is 11, and the parts are numbered D1 to D11 from bottom to top, generating process model A3.

[0052] Refer to the instruction manual Figure 6 , extract the upper surface of process model A1, generate surface S, rotate and move it to face process model A1, surface S is 5mm away from process model A1, and surface S is thickened by 2mm in the -Z direction to generate process model B; establish a plane 4mm below process model B, project the outer dimensions of process model A3 and process model B onto the plane, and construct a flat bottom plate process model C with a thickness of 2mm, with the maximum projection dimension offset 70mm outward.

[0053] Seal all pin holes on process models A3 and B, then import process models A3, B, and C into the slicing software for slicing. Select appropriate slicing parameters (such as layer thickness, line width, etc.) based on the material and configuration. The following special settings are required when setting the slicing parameters for the example parts: When designing supports, select the support form: full support, the support shape is a triangular grid, the spacing is 2.6mm (the grid side length is 5.2mm / 2), and the line is routed once; the parameters for process model C are set to no top or bottom, the outer wall thickness is 2mm, the internal fill pattern is a triangle, the spacing is 5mm, and the line is routed once. After slicing is completed, the 3D printing code for the entire component is generated.

[0054] The part is printed according to the generated print code. After printing, it is heat treated in an oven at 300±5℃ with a heating rate of 2℃ / min and a holding time of 120min. The part base is then fixed and pressed on the CNC machine tool and CNC machining is performed in the following order:

[0055] ① Add the upper surface of D11 to the control machine and drill two pin holes on D11;

[0056] ② Cut part D11 from the overall assembly using a heating wire;

[0057] ③ CNC machine the upper surface of D10 and drill two pin holes on D10;

[0058] ④ Cut part D10 from the overall assembly using a heating wire;

[0059] ⑤ Repeat the above process until part D1 is cut off from the entire assembly;

[0060] ⑥ Add the clamping die (process model B) to the CNC machine and drill two pin holes on the clamping die;

[0061] ⑦ Place D1~D11 on the clamping mold for positioning and fixing respectively, and CNC machine the other side of the part. After the surface processing is completed, mill off the positioning ears to obtain the final shape of the part, and finally obtain D1~D11.

[0062] In the present invention, the processed parts are made of PEEK-based composite materials and are formed according to the above specific processing steps.

[0063] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as an obstacle to the scope of protection of the present invention.

[0064] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0065] The above description is only a preferred embodiment of the present invention and does not constitute any form of obstruction to the present invention. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-efficiency and high-quality processing method for PEEK-based composite material grids, characterized in that: The following steps are involved: Step S1. 3D printing plan design Step S1.

1. Assuming that the original part process digital model is model A, add process allowance to model A, add positioning tabs, and add pin holes to the tabs to generate a new process model A1. Step S1.

2. Select the three lowest points on process model A1 to establish plane P. The distance between the highest point on process model A1 and plane P is the minimum thickness δ that can wrap process model A1. Plane P is offset by a distance δ" along the part's 3D printing growth direction to generate plane P1. Step S1.

3. Offset plane P1 by a distance δ″′ along the part's 3D printing growth direction to generate plane P1″. Also offset plane P by a distance δ″′ in the opposite direction of the part's 3D printing growth direction to generate plane P″. Stretch the grille area along the grille opening, with the upper and lower boundaries of the stretching being planes P1″ and P″, respectively. Finally, generate process model A2. Step S2. Group processing plan design Step S2.

1. Array the process model A2 according to the part 3D printing growth direction to generate the process model A3; Step S3. CNC machining scheme design Step S3.

1. Extract the upper surface of process model A1 to generate surface S. Flip surface S by rotating and moving it. Then move surface S in the opposite direction of the part's 3D printing growth. Then, thicken surface S in the opposite direction of the part's 3D printing growth to generate the clamping mold process model B. Step S3.

2. Create a plane below the process model B, project the dimensions of the process model A3 and the process model B onto the plane, and construct a planar base plate process model C with a maximum projection dimension offset outward by δ″”; Add machined positioning holes outside the projection area on the base plate; Step S4. Auxiliary structure design and slicing parameter setting Step S4.

1. Auxiliary support design: The support form is full support, the support shape is a triangular grid, the spacing is 1 / 2 the length of a single grid side, and the wiring is once; Step S4.

2. Slicing parameter setting: Import process model C, process model B, and process model A3 into the slicing software at the same time and assemble them in their original positions. Set the slicing parameters according to the part structure. Finally, the three process models will generate a 3D printing code; Step S5. Processing procedure design Step S5.

1. Based on process model C, process model B, and process model A3, 3D print the entire component according to the printing code generated in step S4; Step S5.

2. Remove the entire assembly from the 3D printing equipment and place it in an oven for heat treatment; Step S5.

3. After heat treatment, the parts are placed on the CNC machine tool for clamping and CNC machining is performed according to the processing code compiled in the programmed CNC machining sequence.

2. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: Increasing the process allowance for model A includes: increasing the allowance by 2% on the periphery of model A, and increasing the allowance by 1 mm in the thickness direction and on the bottom.

3. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: The positioning lugs added to the model A are distributed on both sides of the model and staggered with each other, and the two lugs are of different shapes.

4. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: When the process model A2 is arrayed, the array distance is δ″+5 mm, and the array quantity a is less than the part width / (δ″+5).

5. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: Before importing process model B and process model A3 into the slicing software, all pin holes on process model B and process model A3 are blocked.

6. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: When setting the slicing parameters according to the part structure, the slicing parameters of process model C are set separately, including: process model C has no top and bottom surface, the outer wall thickness is 2mm, the internal filling pattern is a triangle, the spacing is 5mm, and the routing is once.

7. The method for efficiently and high-quality processing of a PEEK-based composite material grid according to claim 1, characterized in that: Assuming the parts are numbered D1 to Dn from bottom to top, the CNC machining process is performed in the following order: Step S5.3.

1. CNC machine the upper surface of Dn and drill the pin holes on Dn; Step S5.3.

2. Cutting the part Dn from the overall assembly; Step S5.3.

3. CNC machine the upper surface of Dn-1 and drill the pin holes on Dn-1; Step S5.3.

4. Cutting part Dn-1 from the overall assembly; Step S5.3.

5. Repeat the above process until part D1 is cut from the entire assembly; Step S5.3.

6. Add the clamping mold and drill the pin holes on the clamping mold using the CNC machine; Step S5.3.

7. Place D1 to Dn on the clamping mold for positioning and fixing respectively, and CNC machine the other side of the part. After the surface processing is completed, the positioning ears are milled off to obtain the final shape of the part.

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