Thermoplastic composite material 3D printing and continuous carbon fiber composite material composite structure composite material mold and manufacturing method

Abstract

The invention discloses a thermoplastic composite material 3D printing and continuous carbon fiber composite material composite structure composite material mold and a manufacturing method, and belongs to the technical field of aviation equipment manufacturing. The supporting frame is of a discontinuous curved surface supporting structure and is formed by combining a plurality of supporting frame modules. And the molded surface template is an equal-thickness continuous curved surface. Rapid manufacturing of the composite mold in the airplane development process can be achieved, and the problems that when a 3D printing mold is used, the thermal expansion coefficient in the molded surface direction is large, and the product forming precision is poor can be solved.

Description

Technical Field

[0001] This invention belongs to the field of aerospace equipment manufacturing technology, specifically relating to a thermoplastic composite 3D printing and continuous carbon fiber composite structure mold and manufacturing method. Background Technology

[0002] Carbon fiber reinforced resin matrix composites possess high specific strength, specific modulus, and excellent designability and processability, making them widely used in the production of advanced aircraft parts both domestically and internationally. Currently, the aerospace manufacturing field primarily employs autoclave molding processes to manufacture carbon fiber reinforced resin matrix composite parts, with molding dies typically consisting of a metal frame and template combination structure.

[0003] Chinese patent CN 220031236 U discloses a composite molding die, including a frame assembly. A molding die body is disposed on top of the frame assembly. The central longitudinal partition, two side longitudinal partitions, and six transverse partitions are all fixedly connected to the bottom surface of the molding die body. The die is formed using a vacuum bag autoclave process. This type of die can effectively ensure the overall molding accuracy of composite parts. However, the manufacturing process of the metal frame die involves numerous welding, CNC machining, and heat treatment steps, resulting in a long manufacturing cycle and failing to meet the rapid response requirements of die development in aircraft manufacturing. To meet the rapid design and manufacturing needs of composite dies in aircraft manufacturing, existing technologies mainly utilize thermoplastic composite 3D printing dies or multi-point reconfigurable dies.

[0004] Chinese patent CN114290578A discloses a method for manufacturing multi-faceted 3D-printed composite material molds. The method involves printing a rough mold blank using 3D printing technology, followed by CNC precision machining to obtain the finished mold. A special lattice corresponding to the mold's surfaces is designed to provide support for the multi-faceted mold. The mold surfaces and supporting lattice are combined using one or more methods, such as bonding, metal bolts, mortise and tenon structures, and 3D printing. Preferably, the 3D-printed composite material mold and supporting lattice are made of thermoplastic materials such as thermoplastic polyurethane (TPU), nylon (PA), polycarbonate (PC), polylactic acid (PLA), and polyetheretherketone (PEKK), as well as cement, clay, fiber-reinforced plastics, or modified fibers. This type of mold only requires 3D printing of thermoplastic composite materials plus simple machining and joining processes, ensuring the rapid manufacturing of composite molds in aircraft development. Existing thermoplastic composite 3D printing materials exhibit significant anisotropy in their coefficient of thermal expansion (CTE). The CTE is relatively low in the two directions of the slice cross-section, as low as 10 ppm / ℃, similar to traditional metal composite molds (Q235A material, CTE 12 ppm / ℃). However, the CTE is very high in the printing stacking direction, exceeding 60 ppm / ℃. As shown in the figure below, a typical 3D printing composite mold structure has the printing stacking direction in the Y direction, with slice cross-sections in the X and Z directions. Due to the unique nature of thermoplastic composite 3D printing, printing is typically limited to either the X or Y direction of the mold to ensure processability and surface integrity. The composite mold has a high CTE in the X or Y direction, resulting in uneven thermal expansion at high temperatures. Furthermore, the amount of thermal expansion is far greater than that of carbon fiber reinforced resin matrix composites, severely impacting the dimensional accuracy of the formed parts.

[0005] Chinese patent CN104669594B discloses a method for hot pressing of composite material curved surfaces based on a multi-point reconfigurable mold. The method involves leveling the multi-point reconfigurable mold, then sequentially laying an indentation suppression pad, a release cloth, and a composite material sheet on top of the mold. A rubber membrane is then fixed above the composite material sheet using clamps mounted on the outer wall of the molding chamber, forming a sealed enclosure. This method allows for rapid prototyping of different parts by adjusting the mold surface of the multi-point reconfigurable mold, meeting the requirements for rapid manufacturing of composite molds in aircraft development. However, the multi-point reconfigurable mold surface mentioned in this method is discrete, lacking continuous surface support to ensure accuracy during part forming, resulting in poor precision in composite part forming. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of the prior art and provide a thermoplastic composite 3D printing and continuous carbon fiber composite structure composite mold and manufacturing method, which can realize the rapid manufacturing of composite molds in the aircraft development process and reduce the problems of large thermal expansion coefficient along the surface direction and poor product forming accuracy of 3D printed molds during use.

[0007] This invention is achieved through the following technical solution: A thermoplastic composite 3D printing and continuous carbon fiber composite structure mold includes a support frame and a template; the support frame is a discontinuous curved surface support structure, and the support frame is composed of multiple support frame modules; the template is a continuous curved surface of equal thickness.

[0008] Preferably, the support frame module is a standard module.

[0009] Preferably, the various support frame modules are fixedly connected by a first bolt.

[0010] Preferably, the thickness of the template is 5-8 mm.

[0011] Preferably, the template is further provided with reference holes for easy CNC machining and alignment, as well as laser reflective target holes for the projection reference of the composite prepreg layup outline.

[0012] Preferably, the support frame and the template are connected by angle steel, one side of the angle steel is connected to the support frame by a second bolt, and the other side of the angle steel is connected to the template by conformal filler.

[0013] A method for manufacturing a thermoplastic composite 3D printing and continuous carbon fiber composite structure mold includes the following steps: Step S1: Mold template manufacturing: Mold-forming templates are manufactured using thermoplastic composite 3D printing technology; Step S2: Support Frame Manufacturing: The support frame is formed and manufactured using thermoplastic composite 3D printing technology; Step S3: Connect the support frame and the template. Step S4: Overall CNC machining of the mold.

[0014] Preferably, step S1 includes the following steps: Step S11: Design the theoretical model and 3D printing process model of the surface template forming mold; Step S12: Print the surface template forming mold; Step S13: Thermal aging of the molding die for the surface template; Step S14: CNC machining of the molding die for the surface template; Step S15: The template is formed in a hot press.

[0015] Preferably, step S2 includes the following steps: Step S21: Design the process model of the support frame; Step S22: Assemble and connect the various support frame modules; Step S23: CNC machining support frame.

[0016] Preferably, in step S3, according to the theoretical model of the thermoplastic composite 3D printing and continuous carbon fiber composite structure mold, the support frame and the template are combined and connected; each angle steel is installed on the support frame according to the theoretical model position, screw through holes are prepared and bolts are used for fastening; adhesive is evenly applied to the other side of the angle steel and the mating surface of the support frame and the template; the template is covered on the support frame according to the theoretical model position; finally, the composite structure mold is placed in an oven for high-temperature adhesive curing.

[0017] Preferably, the adhesive is a high-temperature resistant epoxy resin with a low coefficient of expansion.

[0018] Preferably, in step S4, according to the theoretical model of thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold, the overall structure of the mold is subjected to CNC rough machining and CNC fine machining to ensure that the theoretical dimensions of the surface are machined in place and the machining accuracy meets the forming requirements of composite parts.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: I. The thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold provided by this invention has the following advantages compared with the traditional metal frame + template combination structure mold: ① The mold is a thermoplastic composite 3D printing and continuous carbon fiber composite structure, which is lighter and easier to use; ② The support frame is a series of standard modules, which can realize advance material preparation. The surface template is made of thermoplastic composite 3D printing process, and the overall manufacturing cycle is shorter, which can meet the rapid manufacturing needs of composite molds in the aircraft development process.

[0020] II. The method for manufacturing a thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold provided by this invention has the following advantages compared with the thermoplastic 3D printing composite mold mentioned in the prior art (a method for manufacturing a multi-faceted 3D printing composite material molding mold): ① The composite structure mold has a larger coefficient of thermal expansion along the Z direction and relatively lower coefficients of thermal expansion along the X and Y directions. The expansion of the mold along the Z direction has little impact on the actual part forming accuracy, while the lower coefficients of thermal expansion along the X and Y directions can effectively ensure the dimensional accuracy of the formed part. ② The template is made of continuous carbon fiber composite material, which has a stable and reliable structure, and the service life of the mold is longer than that of thermoplastic 3D printing composite molding molds.

[0021] III. The method for manufacturing a thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold provided by this invention has the following advantages compared with the multi-point reconfigurable mold mentioned in the prior art (composite material curved surface hot pressing molding method based on multi-point reconfigurable mold): the profile is obtained by continuous fiber composite material layup and curing molding, which can provide continuous profile support for part molding and the part molding accuracy is high. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the composite mold for thermoplastic composite 3D printing and continuous carbon fiber composite structure in this invention; Figure 2 This is a schematic diagram of the supporting frame in this invention. Figure 1 ; Figure 3 This is a schematic diagram of the supporting frame in this invention. Figure 2 ; Figure 4 This is a schematic diagram of the structure of the template in this invention; Figure 5 This is a schematic diagram showing the connection between the support frame and the template in this invention; Figure 6 This is a flowchart of the manufacturing method of thermoplastic composite 3D printing and continuous carbon fiber composite structure mold in this invention; Figure 7 This is a schematic diagram of the molding die and the blank of the molding template in this invention; Figure 8 This is a schematic diagram showing the relationship between the theoretical model of the medium-sized surface template forming mold and the 3D printing mold process model of the present invention; Figure 9 This is a schematic diagram of the supporting frame process model in this invention; The components are: 1. Support frame; 11. Support frame module; 12. First bolt; 13. Standard module; 2. Profile template; 21. Laser reflective target hole; 22. Reference hole; 3. Angle steel; 4. Second bolt; 5. Conformal filler; 6. Profile template forming mold; 7. Profile mold blank; 8. Forming surface of profile mold forming mold; 9. Machining allowance a of profile template; 10. Standard support frame module. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0024] Example 1 like Figures 1-5 As shown, this embodiment is applicable to molding dies for composite products manufactured at medium temperature (120°C).

[0025] A thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold includes a support frame 1 and a template 2. The support frame is a discontinuous curved surface support structure, which is formed by CNC machining of multiple support frame modules 11. The support frame module 11 is a series of standard modules 13, which are formed by 3D printing of short fiber reinforced thermoplastic resin composite material with a fiber length of 5mm. The resin can be polycarbonate (PC) with a temperature resistance of 130℃. The support frame modules 11 are fixedly connected by first bolts 12. After overall CNC machining, they form an integral discontinuous support structure of the template 2, ensuring the overall structural strength of the mold. The template 2 is a continuous curved surface of uniform thickness (thickness can be 5~8mm), and the material can be continuous carbon fiber composite prepreg laid up and formed by medium temperature molding (120℃). One side of the template 2 is curved and connected to the support frame 1, while the other side serves as the molding surface for composite skin forming. Prepreg is laid on the template surface, and the composite skin parts are formed using a vacuum bag-autoclave molding method. Specifically, the template 2 is also equipped with reference holes 22 for easy CNC machining and alignment, and laser reflective target holes 21 for the projection reference of the composite prepreg's overlay outline. The support frame 1 and the template 2 are connected by angle steel 3. One side of the angle steel 3 is connected to the support frame by a second bolt 4, while the other side is bonded to the template surface by curing a conformal filler 5 with a liquid adhesive, ensuring that the support frame 1 and the template 2 form a rigid whole.

[0026] The thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold of this embodiment has a simple structure, short manufacturing cycle, and low coefficient of thermal expansion along the X and Y directions, which can effectively ensure the dimensional accuracy of the parts and the high reliability of the parts. It can meet the rapid manufacturing of thermoplastic composite molding molds in the aircraft development process.

[0027] Example 2 This embodiment presents a thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold, suitable for molding dies for high-temperature (180℃) composite products. Its structure is the same as in Embodiment 1. The difference is that the serialized standard module 13 is formed by 3D printing from short-fiber reinforced thermoplastic resin composite material. The resin can be polycarbonate (PC) with a temperature resistance of 220℃. The template 2 can be made from high-temperature (180℃) continuous carbon fiber composite prepreg.

[0028] The thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold of this embodiment has a simple structure, short manufacturing cycle, and low coefficient of thermal expansion along the X and Y directions, which can effectively ensure the dimensional accuracy of the parts and the high reliability of the parts. It can meet the rapid manufacturing of high temperature composite material molding molds in the aircraft development process.

[0029] Example 3 like Figures 6-9 As shown, a thermoplastic composite 3D printing mold with the above-mentioned structure, suitable for medium-temperature molding (120℃) composite products, is manufactured by the following steps: Step S1: Manufacturing the template 2: The mold-forming template 2, manufactured using thermoplastic composite 3D printing technology, includes the following sub-steps: Step S11: Design the theoretical model and process model of the 6-shaped template forming mold; Based on the theoretical model of the thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold, a theoretical model and a 3D printing process model of the surface template forming mold 6 are designed. Following the mold surface and supporting lattice method mentioned in the invention patent "A Method for Manufacturing a Multi-Surface 3D Printed Composite Material Molding Mold," the structure of the surface template forming mold 6, printed along the X or Y direction of the mold, is designed. The surface portion of the process model of the surface template forming mold 6 is consistent with the surface mold blank 7. After uniformly reducing the thickness by a certain thickness 'a' along the surface direction, it becomes the forming surface 8 of the surface mold forming mold. The uniformly reduced thickness 'a' (the machining allowance 'a9' of the surface template) is typically 3-5 mm, and this thickness is the allowance for overall CNC machining after the template surface is laid up and formed.

[0030] S12: Printing surface template forming mold 6; In the 3D printing editing software, the process model of the surface template forming mold 6 is processed in layers to determine the two-dimensional cross-sectional data of each printing layer. Process parameters including printing path, printing layer thickness and printing line width are set. Carbon fiber reinforced thermoresin particles are placed in the 3D printing equipment to print the process model of the surface template forming mold 6. The fiber length is 5mm and the resin can be polycarbonate (PC) with a temperature resistance of 130℃.

[0031] S13: Surface Template Molding Die 6 - Heat Aging The 3D printing template forming mold 6 is placed in an oven and subjected to heat aging treatment according to certain heating parameters to eliminate internal stress in 3D printing.

[0032] S14: Surface template forming mold 6 CNC machining; The printed surface template forming mold 6 is subjected to CNC roughing and finishing until it conforms to the theoretical model of the surface template forming mold 6.

[0033] S15: Surface template 2 autoclave forming; Continuous carbon fiber composite prepreg is laid on the printed and CNC-machined template forming mold 6. The layup thickness is the theoretical thickness of the template plus the CNC machining allowance 'a'. After laying, the template 2 is formed using a vacuum bag-autoclave molding method. The continuous carbon fiber composite prepreg can be a medium-temperature molding (120℃) continuous carbon fiber composite prepreg.

[0034] Step S2: Manufacturing of support frame 1: The support frame 1 is formed and manufactured using thermoplastic composite 3D printing technology, and its sub-steps include: Step S21: Design the process model of support frame 1 Using the thermoplastic composite 3D printing and continuous carbon fiber composite structure mold as the theoretical model, a process model of the support frame 1 is designed. Standard support frame modules 10 of different specifications are selected and combined. The outer dimensions of the combined support frame 1 process model are slightly larger than the maximum outer dimensions of the theoretical composite part. The height of each module should be greater than the highest height of the theoretical model at that position by more than 10mm, as the minimum allowance for CNC machining. Figure 8 As shown, in this embodiment, five standard support frame modules 10 of 200×400×400 and three of 250×400×400 are combined to form a support frame process model. The standard support frame module 10 is formed by 3D printing process using short fiber reinforced thermoplastic resin composite material. The fiber length is 5mm and the resin can be polycarbonate (PC) with a temperature resistance of 130℃.

[0035] Step S22: Assemble and connect each support frame module 1 According to the process model of the support frame 1 designed in S21, standard support frame modules 10 of corresponding specifications are selected and combined, and the support frame modules 11 are connected by the first bolt 12 to form the overall frame support 1 structure. The standard support frame modules 10 of each specification can be printed and heat-aged in real time according to the support frame process model, or they can be printed in advance using thermoplastic composite 3D printing technology and heat-aged for later use, further shortening the manufacturing cycle of composite molds.

[0036] Step S23: CNC machining support frame 1 According to the theoretical model of the support frame, the overall structure of the support frame 1 is subjected to CNC rough machining and CNC fine machining to ensure the formation of an overall discontinuous support structure of the surface template.

[0037] Step S3: Assemble and connect the support frame 1 and the template 2: Based on the theoretical model of the thermoplastic composite 3D printing and continuous carbon fiber composite structure mold, the supporting frame 1 and the template 2 are combined and connected. Each angle steel 3 is installed onto the supporting frame 1 according to the theoretical model position, screw holes are prepared, and the mold is secured with a second bolt 4. Adhesive is evenly applied to the other side of the angle steel 3 and the mating surface of the supporting frame 1 and the template 2. The template 2 is then placed on top of the supporting frame 1 according to the theoretical model position. Finally, the composite structure mold is placed in an oven for high-temperature adhesive curing. The adhesive can be a high-temperature resistant, low-expansion coefficient epoxy resin, characterized by a paste-like consistency at room temperature, certain fluidity and viscosity, and curing at high temperatures.

[0038] Step S4: Overall CNC machining of the mold Based on the theoretical model of thermoplastic composite 3D printing and continuous carbon fiber composite composite structure mold, the overall structure of the mold is subjected to CNC rough machining and CNC fine machining to ensure that the theoretical dimensions of the surface are machined in place and that the machining accuracy meets the forming requirements of composite parts.

[0039] This embodiment describes a method for preparing a thermoplastic composite 3D printing and continuous carbon fiber composite composite mold for medium-temperature molding (120℃) composite products. The method involves manufacturing a molding template 2 using thermoplastic composite 3D printing technology, molding the template 2, and forming the support frame 1 by CNC machining a combination of standard modules of thermoplastic 3D printed composite materials. The connection between the support frame 1 and the template 2 results in high CNC machining efficiency and allows for the rapid production of the required composite material part molding mold. Compared with the manufacturing of molds using a metal frame + template combination structure, this method has lower manufacturing difficulty and shorter manufacturing cycle.

[0040] Example 4 This embodiment describes a method for manufacturing a thermoplastic composite 3D printing and continuous carbon fiber composite structure mold, applicable to molding dies for high-temperature (180℃) composite products. The manufacturing method is the same as in Embodiment 3. The difference is that the serialized standard module 13 is formed by 3D printing from chopped fiber reinforced thermoplastic resin composite material. The resin can be polycarbonate (PC) with a temperature resistance of 220℃. The template material can be a continuous carbon fiber composite prepreg laid up and formed at high temperature (180℃). The thermoplastic 3D printing material used in the template molding die is polycarbonate (PC) with a temperature resistance of 220℃.

[0041] This embodiment describes a method for preparing a thermoplastic composite 3D printing and continuous carbon fiber composite composite mold for high-temperature molding (180℃) composite products. The method involves manufacturing a surface template 2 using thermoplastic composite 3D printing technology, and shaping the surface template 2. The support frame 1 is CNC machined by combining standard modules of thermoplastic 3D printed composite materials. The connection between the support frame 1 and the surface template 2 results in high CNC machining efficiency, enabling the rapid production of the required composite material part molding mold. Compared with the manufacturing of molds using a metal frame + template combination structure, this method has lower manufacturing difficulty and shorter manufacturing cycle.

[0042] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold, characterized by: The support frame is a non-continuous curved surface support structure, and the support frame comprises a plurality of support frame modules combined together.

2. A thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold according to claim 1, characterized in that: The support frame module is a standard module.

3. A thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold according to claim 1, characterized in that: Each support frame module is fixedly connected by first bolts.

4. The thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold of claim 1, wherein: The thickness of the profile template is 5-8 mm.

5. A thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold according to claim 1, characterized in that: The profile template is further provided with reference holes for facilitating numerical control machining and alignment, and laser reflection target holes for projecting the profile of the prepreg laying of the composite material.

6. A thermoplastic composite 3D printing and continuous carbon fiber composite hybrid structure composite mold according to claim 1, characterized in that: The support frame and the profile template are connected by angle steels, one side of the angle steel is connected with the support frame by second bolts, and the other side of the angle steel is connected with the profile template by a conformal filler.

7. The method of claim 1-6, wherein the method further comprises the steps of: providing a mold having a plurality of cavities; and filling the cavities with a thermoplastic material. The method comprises the following steps: Step S1: manufacturing the profile template: a mold forming profile template is manufactured by a thermoplastic composite 3D printing process; Step S2: manufacturing the support frame: the support frame is formed and manufactured by a thermoplastic composite 3D printing process; Step S3: combining and connecting the support frame and the profile template; Step S4: numerical control machining of the mold as a whole.

8. The method of claim 7, wherein the method further comprises: 3D printing a mold for the thermoplastic composite and continuous carbon fiber composite hybrid structure. In the step S1, the following steps are included: Step S11: designing a profile template forming mold theoretical model and a 3D printing process model; Step S12: printing the profile template forming mold; Step S13: heat aging of the profile template forming mold; Step S14: numerical control machining of the profile template forming mold; Step S15: autoclave forming of the profile template.

9. The method of claim 7, wherein the method further comprises: 3D printing a mold for the thermoplastic composite and continuous carbon fiber composite hybrid structure. In the step S2, the following steps are included: Step S21: designing a support frame process model; Step S22: combining and connecting each support frame module; Step S23: numerical control machining of the support frame.

10. The method of claim 7, wherein the method further comprises: 3D printing a mold for the thermoplastic composite and continuous carbon fiber composite hybrid structure. In the step S3, the support frame and the profile template are combined and connected according to the theoretical model of the thermoplastic composite 3D printing and the continuous carbon fiber composite structure composite mold; each angle steel is installed on the support frame according to the position of the theoretical model, the screw through hole is prepared, and the bolt is connected and fastened; the adhesive is uniformly coated on the other side of the angle steel and the bonding surface of the support frame and the profile template, and the profile template is covered above the support frame according to the theoretical numerical model position; finally, the composite structure composite mold is put into an oven for high-temperature adhesive curing.

11. The method of claim 10, wherein the method further comprises: 2D printing the mold material on the build platform; and 3D printing the thermoplastic material on the mold material. The adhesive is a high-temperature resistant low-expansion coefficient epoxy resin.

12. The method of claim 7, wherein the method further comprises: 3D printing a mold for the thermoplastic composite and continuous carbon fiber composite hybrid structure. In the step S4, according to the theoretical model of the thermoplastic composite 3D printing and the continuous carbon fiber composite structure composite mold, numerical control rough machining and numerical control finishing are respectively performed on the overall structure of the mold to ensure that the profile theoretical size is machined in place, and the machining precision meets the forming requirements of the composite part.

Images