Production device and method of special-shaped continuous fiber prepreg for 3D printing

Abstract

The present invention relates to a production device and method for a special-shaped continuous fiber prepreg for 3D printing, the method is: after a continuous fiber bundle is impregnated in a resin melt, it passes through a special-shaped die and then cools to obtain a special-shaped continuous fiber prepreg for 3D printing; the special-shaped die is a die with a regular star-shaped cross section, the regular star is an n-gon, the side length is l, the diameter of the continuous fiber bundle is d, l>π×d / n; the production device includes a melt impregnation tank, the outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, a heater and a special-shaped die connected to the melt impregnation tank outlet are provided inside, and a thermoplastic resin feeder is provided on the top. The method of the present invention improves the bonding force of the fiber-matrix interface, and at the same time improves the comprehensive mechanical properties and service life of the product; the device of the present invention realizes the 3D printing production of continuous fiber reinforced thermoplastic composite materials, which is convenient and simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced composite materials, and in particular relates to a production device and method for special-shaped continuous fiber prepregs for 3D printing. Background Art

[0002] In recent years, the demand for lightweight, high-strength, fast and precise manufacturing, environmental protection and sustainable development in various fields has gradually increased, which has led to the rapid development of fiber-reinforced thermoplastic composites, and the growth rate has gradually surpassed that of fiber-reinforced thermosetting composites. Among fiber-reinforced thermoplastic composites, continuous fiber reinforcement has the best effect. When continuous fiber-reinforced thermoplastic composites are subjected to force, the continuous fibers as the reinforcement part are the main receptors of the load, and the continuity of the fibers can effectively transfer the load from the thermoplastic matrix to the reinforcing fibers. Therefore, continuous fiber-reinforced thermoplastic composites can meet the high-strength requirements in certain practical application scenarios, while also having a variety of excellent properties such as light weight, high fatigue resistance, and structural and functional integration. In particular, such composite materials with high thermal performance thermoplastic resins (such as PEEK, PEKK, etc.) as the matrix have gradually been well applied in high-tech fields such as transportation, industrial manufacturing, national defense and military, and aerospace.

[0003] At present, there are many molding methods for continuous fiber reinforced thermoplastic composites, and some molding processes are relatively mature. However, the mainstream molding process has problems such as low product precision, low degree of product customization and production intelligence, limited to the production of large devices, and high equipment costs. Therefore, the emergence of Fused Deposition Modeling (FDM), a representative of 3D printing technology, has provided new possibilities for the processing and molding of continuous fiber reinforced thermoplastic composites.

[0004] So far, there are three main ways to use FDM technology to form continuous fiber reinforced thermoplastic composite materials. The first is to extrude the reinforcing fiber and thermoplastic wire from two 3D printing nozzles respectively, and complete the molding through the method of matrix deposition-reinforcement fiber deposition-matrix deposition; the second is to first prepare a continuous fiber thermoplastic prepreg wire that meets the FDM process requirements, and then use this prepreg wire to complete the molding through a single 3D printing nozzle; the third is that the thermoplastic wire and continuous fiber enter the modified special 3D printing nozzle at the same time, the resin completes the melting and impregnation of the fiber in the 3D printing nozzle, and then wraps the continuous fiber and extrude it from the nozzle for deposition molding. Among them, the third method has higher molding accuracy, unlimited matrix material selection, and gets rid of the dependence on prepreg and dual 3D printing nozzles. It is currently the most feasible solution for FDM to prepare continuous fiber reinforced thermoplastic composites.

[0005] However, the only one-time impregnation of the matrix and the reinforcing fibers in the print nozzle is insufficient, especially when using commercially available carbon fiber tows with epoxy sizing agents on the surface, the thermoplastic matrix still has a high viscosity in the molten state, and it is difficult to fully penetrate into the continuous carbon fiber tows, and can only be loosely distributed around it, which seriously affects the interface bonding between the matrix and the reinforcing fibers, thereby causing the final comprehensive mechanical properties of the product to be poor, and there is a big gap compared to the composite material finally obtained using the traditional process. Therefore, how to improve the interface bonding between the fiber-matrix becomes a key problem to be solved when using this method to prepare a composite material. The main means to improve the interface bonding is fiber surface modification. At present, the schemes for the surface modification of continuous fibers suitable for FDM that have been developed have means such as pre-production of pre-impregnated wires and plasma treatment in advance. These schemes make the production steps cumbersome, or bring higher equipment costs, especially for high thermal performance thermoplastic matrices (such as PEKK, PEEK, etc.), which are not targeted, and seriously limit the application of 3D printing technology in the field of preparing high-performance fiber-reinforced composite materials. Summary of the invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and to provide a device and method for preparing special-shaped continuous fiber prepregs. The present invention can significantly solve the problem of weak interface bonding between continuous fiber bundles and thermoplastic matrix during 3D printing, improve the anisotropy of the parts, and effectively enhance the mechanical properties of the parts.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for producing a special-shaped continuous fiber prepreg for 3D printing, wherein a continuous fiber bundle is impregnated in a resin melt, passed through a special-shaped die, and then cooled to obtain the special-shaped continuous fiber prepreg for 3D printing;

[0009] The special-shaped die has a regular star-shaped cross section (the function of the special-shaped die is to shape the continuous fiber bundle, so as to achieve its close integration with the thermoplastic matrix interface in the subsequent 3D printing process). The regular star shape is an n-gon with a side length of l, and the diameter of the continuous fiber bundle is d, l>π×d / n.

[0010] The special-shaped die makes the cross section of the continuous fiber prepreg in a star shape. The star shape increases the contact area between the resin and the fiber. The increase in contact area can effectively achieve a close combination of the fiber and the resin during 3D printing. For example, if the cross section of a continuous fiber prepreg with a diameter of 1mm and a length of 100mm is an ordinary circle, the maximum area (i.e., the side area) that contacts the resin during 3D printing is about 314mm. 2If its cross section is a regular star shape and the regular star shape is an octagon, the maximum area (i.e., the side area) that contacts the resin during 3D printing is approximately 433 mm 2 , which is about 38% higher than that of the continuous fiber prepreg with a circular cross-section. Therefore, the special-shaped die enables the fiber and resin to be closely combined in the subsequent 3D printing process.

[0011] In order to ensure that the contact area between the continuous fiber prepreg with a regular star-shaped cross-section and the resin is larger than that of the continuous fiber prepreg with an ordinary circular cross-section, the circumference of the regular star-shaped cross-section must be larger than the circumference of a circle of the same size. Therefore, the fiber bundle diameter (i.e., the inner diameter of the special-shaped die) is set to d. For a regular star-shaped n-gon with a side length of l, n*l>π*d.

[0012] In addition to being a true star shape, the cross-section of the special-shaped die can also be in other shapes with grooves on the edges, such as a gear shape. In short, in theory, as long as the cross-sectional edges of the produced prepreg wire have grooves, the effect of tightly combining the fiber and the resin in the subsequent 3D printing process can be achieved. Since 3D printing technology has very high requirements on the precision of products, the cross-sectional diameter of continuous fiber prepregs suitable for 3D printing generally does not exceed 1 mm. It is actually difficult to process special-shaped dies of "other shapes with grooves on the edges" other than true star-shaped polygons at such a small size, so only the true star shape is selected in the present invention.

[0013] As the preferred technical solution:

[0014] A method for producing a special-shaped continuous fiber prepreg for 3D printing as described above, wherein the resin is polyetheretherketone (PEEK) or polyetherketoneketone (PEKK) with a melt index of ≤5g / 10min at a temperature of 350°C and a load (i.e., the total weight of the pressure rod and the weight) of 2.16kg, or polyetherimide (PEI) with a melt index of >5g / 10min and ≤10g / 10min at a temperature of 320°C and a load of 2.16kg, or polyvinylidene fluoride (PVDF) with a melt index of >5g / 10min and ≤10g / 10min at a temperature of 240°C and a load of 2.16kg, or Polylactic acid (PLA) having a melt index > 10 g / 10 min at 180°C and a load of 2.16 kg, or polyamide (PA6 / PA66) having a melt index > 10 g / 10 min at 200°C and a load of 2.16 kg, or acrylonitrile-butadiene-styrene (ABS) having a melt index > 10 g / 10 min at 190°C and a load of 2.16 kg, or polypropylene (PP) having a melt index > 10 g / 10 min at 180°C and a load of 2.16 kg. In the present invention, the melt index of the polymer raw material is only limited to the melt index at a specified temperature and does not involve time.

[0015] As described above, in the method for producing a special-shaped continuous fiber prepreg for 3D printing, when the resin is polyetheretherketone (PEEK), polyetherketoneketone (PEKK) or polyetherimide (PEI), the temperature of the resin melt is 320-350°C; when the resin is polyamide (PA6 / PA66) or polyvinylidene fluoride (PVDF), the temperature of the resin melt is 200-250°C; when the resin is polylactic acid (PLA), polypropylene (PP) or acrylonitrile-butadiene-styrene (ABS), the temperature of the resin melt is 180-200°C.

[0016] As described above, in the method for producing a special-shaped continuous fiber prepreg for 3D printing, when the resin is polyetheretherketone (PEEK), polyetherketoneketone (PEKK) or polyetherimide (PEI), the tension of the continuous fiber bundle during the impregnation is 15 to 20N; when the resin is polylactic acid (PLA), polyamide (PA6 / PA66) or polyvinylidene fluoride (PVDF), the tension of the continuous fiber bundle during the impregnation is 10 to 15N; when the resin is polypropylene (PP) or acrylonitrile-butadiene-styrene (ABS), the tension of the continuous fiber bundle during the impregnation is 5 to 10N.

[0017] In the method for producing a special-shaped continuous fiber prepreg for 3D printing as described above, the impregnation time t=L / v; L is the length of the continuous fiber bundle impregnated in the resin melt, in mm; the unit of v is mm / s; when the resin is polyetheretherketone (PEEK) or polyetherketoneketone (PEKK), v is 2 mm / s; when the resin is polyetherimide (PEI) or polyvinylidene fluoride (PVDF), v is 2 to 6 mm / s; when the resin is polylactic acid (PLA), polyamide (PA6 / PA66), acrylonitrile-butadiene-styrene (ABS) or polypropylene (PP), v is 6 to 10 mm / s.

[0018] In the method for producing a special-shaped continuous fiber prepreg for 3D printing as described above, the continuous fiber bundle is a carbon fiber bundle with 1000 single filaments.

[0019] The present invention also provides a production device for special-shaped continuous fiber prepreg for 3D printing, comprising a melt impregnation tank, a fiber bundle limiting hole connected to the melt impregnation tank inlet for continuous fiber bundles to pass through is arranged on the outside of the melt impregnation tank, a heater and a special-shaped die connected to the melt impregnation tank outlet are arranged inside, and a thermoplastic resin feeder is arranged on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star is an n-gon with a side length of l, and the diameter of the continuous fiber bundle is d, l>π×d / n; the fiber bundle limiting hole is intended to fix the continuous fiber bundle into the impregnation feeding position while preventing the fiber from being pulled out, and the melt impregnation tank inlet is connected to the impregnation tank wall, so as to avoid melt leakage and fiber bundles being rubbed at the inlet; the special-shaped die is intended to better combine with the matrix in the subsequent 3D printing implementation process while ensuring the smooth preparation of the prepreg fiber bundle;

[0020] As the preferred technical solution:

[0021] As described above, in the production device for special-shaped continuous fiber prepregs for 3D printing, there is also a continuous fiber bundle tensioning mechanism inside the melt impregnation tank, which is used to adjust the tension of the fiber bundle and thus control the degree of penetration of the melt into the continuous fiber bundle.

[0022] As described above, a production device for special-shaped continuous fiber prepregs for 3D printing, the continuous fiber bundle tensioning mechanism is composed of a first impregnation roller, a second impregnation roller and a third impregnation roller arranged in sequence along the fiber running direction, the second impregnation roller is located between the first impregnation roller and the third impregnation roller, and is located below the first impregnation roller and the third impregnation roller; the horizontal distance between the first impregnation roller and the second impregnation roller is 60±5mm, and the vertical distance is 80±5mm; the horizontal distance between the second impregnation roller and the third impregnation roller is 60±5mm, and the vertical distance is 80±5mm; the horizontal distance between the fiber bundle limiting hole and the first impregnation roller is 80±5mm, and the vertical distance is 60±5mm; the horizontal distance between the special-shaped die and the third impregnation roller is 50±5mm, and the vertical distance is 5±1mm.

[0023] The production device of a special-shaped continuous fiber prepreg for 3D printing as described above also includes a cooler located in front of the outlet of the molten impregnation tank along the fiber running direction, and a first cooling fan and a second cooling fan are arranged in the cooler; the horizontal distance between the outlet of the molten impregnation tank and the cooler is 1 to 3 cm.

[0024] As described above, a production device for special-shaped continuous fiber prepregs for 3D printing also includes a traction machine located in front of the cooler along the fiber running direction, and a first reel and a second reel are provided in the traction machine; the horizontal distance between the cooler and the traction machine is 5 to 10 cm; the rotation speed of the first reel and the second reel is 2 to 10 mm / s, and the movement speed of the fiber bundle is controlled by adjusting the rotation speed of the traction machine to effectively impregnate it with melts of different viscosities.

[0025] As described above, in a production device for special-shaped continuous fiber prepregs for 3D printing, the material of the fiber bundle limiting hole is a ceramic material with a smooth surface, the inlet of the molten impregnation tank is trumpet-shaped, and the outlet of the impregnation tank is a gate-type switch port operated by a switch rod, which is intended to be used for replacing special-shaped die.

[0026] As described above, in a production device for special-shaped continuous fiber prepreg for 3D printing, the feeding port of the thermoplastic resin feeder is in the shape of a conical funnel, and the feeding port is connected to a material pipe; the thermoplastic resin feeder has a built-in electric-controlled screw to allow the thermoplastic resin pellets to enter the impregnation tank at a uniform speed.

[0027] As described above, in a production device for special-shaped continuous fiber prepregs for 3D printing, a heat-conducting copper plate is provided between the first cooling fan and the second cooling fan in the cooler and the fiber bundles. The purpose of providing the heat-conducting copper plate is to separate the first cooling fan, the second cooling fan and the fiber bundles to prevent high-speed airflow from having an adverse effect on the molding of the prepreg bundles.

[0028] Beneficial Effects

[0029] (1) The device of the present invention, according to the process characteristics of the production process of thermoplastic resin fiber prepreg, forms an effective special-shaped cross-section of the continuous fiber prepreg tow by adding a special-shaped die, cooperates with the melt impregnation equipment to effectively impregnate and penetrate the continuous fiber tow, and optimizes the processing and process parameters of each component of the device. It can effectively solve the problems of loose bonding between the matrix and the reinforcing fiber and inability to produce effective interface bonding during the 3D printing process, and at the same time helps to realize the 3D printing production of two-component continuous fiber reinforced thermoplastic composite materials, and effectively achieves the structural-functional integration goal of the product;

[0030] (2) The present invention can improve the continuous reinforcing fibers before the 3D printing extrusion process of the composite material, making it more suitable for preparing continuous fiber reinforced thermoplastic composite materials by 3D printing process. The method of the present invention can make the continuous reinforcing fiber bundles used for 3D printing produce special-shaped cross-sections. The existence of such special-shaped cross-sections can effectively attach the thermoplastic matrix to the reinforcing fibers during the 3D printing process. The good compatibility between the printing matrix and the prepreg bundle can significantly improve the bonding of the fiber-matrix interface, effectively reduce the stress failure and obvious anisotropy caused by the interface bonding force of the 3D printed parts during service, improve the comprehensive mechanical properties and service life of the parts, and have great significance for manufacturing high-performance complex structure continuous fiber reinforced thermoplastic composite products. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of a device for producing continuous fiber thermoplastic prepreg tows according to the present invention;

[0032] Figure 2 Schematic diagram of a special-shaped die in which the regular star shape is a regular quadrilateral of the present invention, wherein (a) is a longitudinal cross-sectional schematic diagram, and (b) is a three-dimensional structural schematic diagram;

[0033] Figure 3 Schematic diagram of a special-shaped die of the present invention in which the regular star shape is a regular hexagon, wherein (a) is a longitudinal cross-sectional schematic diagram, and (b) is a three-dimensional structural schematic diagram;

[0034] Figure 4 This is a schematic cross-sectional view of a special-shaped continuous fiber prepreg for 3D printing produced by the present invention using a regular quadrilateral special-shaped die;

[0035] Figure 5 This is a schematic cross-sectional view of a special-shaped continuous fiber prepreg for 3D printing produced by the present invention using a regular hexagonal special-shaped die;

[0036] Among them, 1-1-continuous fiber bundle, 2-fiber reel, 3-fiber bundle limiting hole, 4-1-molten impregnation tank inlet, 4-2-first impregnation roller, 4-3-second impregnation roller, 4-4-third impregnation roller, 4-5-special-shaped die, 4-6-molten impregnation tank outlet, 5-thermoplastic resin feeder, 5-1-feeding port, 6-cooler, 6-1-first cooling fan, 6-2-second cooling fan, 7-traction machine, 7-1-first reel, 7-2-second reel, 8-continuous fiber bundle with special-shaped cross-section, 8-1-resin. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] A production device for special-shaped continuous fiber prepreg for 3D printing, such as Figures 1 to 3 As shown, it includes a fiber reel 2, a melt impregnation tank, a cooler 6 and a traction machine 7;

[0039] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole 3 connected to the melt impregnation tank inlet 4-1 for the continuous fiber bundle 1-1 to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die 4-5 connected to the melt impregnation tank outlet 4-6, and a thermoplastic resin feeder 5 is provided on the top; the special-shaped die 4-5 is a die with a regular star-shaped cross section, the regular star shape is an n-gon with a side length of l, the diameter of the continuous fiber bundle 1-1 is d, in, Figures 2-3 Shown are schematic diagrams of special-shaped die with regular star shapes being regular quadrilaterals and regular hexagons;

[0040] The continuous fiber bundle tensioning mechanism is composed of a first dipping roller 4-2, a second dipping roller 4-3 and a third dipping roller 4-4 which are arranged in sequence along the fiber running direction. The second dipping roller 4-3 is located between the first dipping roller 4-2 and the third dipping roller 4-4 and below them. The horizontal distance between the first dipping roller 4-2 and the second dipping roller 4-3 is 60±5mm, and the vertical distance is 80±5mm. The horizontal distance between the second dipping roller 4-3 and the third dipping roller 4-4 is 60±5mm, and the vertical distance is 80±5mm. The horizontal distance between the fiber bundle limiting hole 3 and the first dipping roller 4-2 is 80±5mm, and the vertical distance is 60±5mm. The horizontal distance between the special-shaped die 4-5 and the third dipping roller 4-4 is 50±5mm, and the vertical distance is 5±1mm.

[0041] Along the fiber running direction, the cooler 6 is located in front of the melt impregnation tank outlet 4-6, and the cooler 6 is provided with a first cooling fan 6-1 and a second cooling fan 6-2; the horizontal distance between the melt impregnation tank outlet 4-6 and the cooler 6 is 1 to 3 cm;

[0042] Along the fiber running direction, the traction machine 7 is located in front of the cooler 6, and the traction machine 7 is provided with a first reel 7-1 and a second reel 7-2; the horizontal distance between the cooler 6 and the traction machine 7 is 5 to 10 cm; the rotation speed of the first reel 7-1 and the second reel 7-2 is 2 to 10 mm / s.

[0043] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0044] (1) Preparation of raw materials;

[0045] Resin 8-1;

[0046] Continuous fiber bundle 1-1: a carbon fiber bundle having 1000 filaments;

[0047] (2) The continuous fiber bundle 1-1 is pulled out from the fiber reel 2 by a threading needle, passes through the fiber bundle limiting holes 3 in sequence, and then enters the inlet 4-1 of the melt impregnation tank;

[0048] (3) The continuous fiber bundle 1-1 is sequentially passed through the first dipping roller 4-2, the second dipping roller 4-3, and the third dipping roller 4-4 in the melt impregnation tank, so that the continuous fiber bundle 1-1 forms a "V" shape in the melt impregnation tank, and then sequentially passes through the special-shaped die 4-5, the melt impregnation tank outlet 4-6, and the cooler 6 to be fixed between the first reel 7-1 and the second reel 7-2 in the traction machine 7 to form a certain tension;

[0049] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature that can melt the resin, add the resin to the feeding port 5-1 of the thermoplastic resin feeder 5, and when the amount of resin added is close to the capacity limit of the melt impregnation tank, turn on the traction machine 7;

[0050] (5) When the resin melt appears on the surface of the continuous fiber bundle 1-1 drawn out from the molten impregnation tank, the cooler 6 is turned on to rotate the first cooling fan 6-1 and the second cooling fan 6-2 at high speed to cool the resin melt and form a continuous fiber bundle 8 with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0051] The immersion time of the continuous fiber bundle 1-1 in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle 1-1 immersed in the resin melt, in mm; and v is in mm / s.

[0052] like Figures 4-5As shown, they are schematic cross-sectional views of special-shaped continuous fiber prepregs for 3D printing produced using regular quadrilateral and regular hexagonal special-shaped die, respectively. The final special-shaped continuous fiber prepregs for 3D printing are composed of a continuous fiber bundle 1-1 and a resin 8-1.

[0053] Now, the specific embodiments are described. It should be noted that the test methods of the performance indicators involved in the following embodiments are as follows:

[0054] Interlaminar shear strength: The interlaminar shear strength of 3D printed continuous fiber reinforced thermoplastic composites was tested according to JC / T 773-2010 "Determination of interlaminar shear strength of fiber reinforced plastics by short beam method".

[0055] Flexural strength: The flexural strength of 3D printed continuous fiber reinforced thermoplastic composites was tested according to GB T 1449-2005 “Test method for flexural properties of fiber reinforced plastics”.

[0056] Tensile strength: The tensile strength of 3D printed continuous fiber reinforced thermoplastic composites was tested according to GB 1447-2005 “Test method for tensile properties of fiber reinforced plastics”.

[0057] Example 1

[0058] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0059] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.25mm, and d is 0.6mm;

[0060] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 50 mm, and the vertical distance is 5 mm;

[0061] Along the fiber running direction, the cooler is located in front of the outlet of the melt impregnation tank, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the outlet of the melt impregnation tank and the cooler is 3 cm;

[0062] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 10 cm; the rotation speed of the first reel and the second reel is 7 mm / s.

[0063] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0064] (1) Preparation of raw materials;

[0065] Resin: Polyamide 6 with a melt index of 17.6 g / 10 min at 200°C and a load of 2.16 kg;

[0066] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0067] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0068] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 12N;

[0069] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and when the amount of resin added is close to the capacity limit of the melt impregnation tank, turn on the traction machine; wherein the temperature of the resin melt is 200° C.;

[0070] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0071] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0072] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0073] The above-mentioned special-shaped continuous fiber prepreg and polyamide 6 filament (manufacturer is 3DXTECH, brand name is AmideX TM Nylon6) is used as a raw material to perform 3D printing to prepare a composite material. The specific printing process is as follows: a thermoplastic wire (polyamide 6 wire) and a profiled continuous fiber prepreg simultaneously enter a heated nozzle with a double feed port, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Driven by a driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on a heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 220°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0074] The interlaminar shear strength of the composite material finally prepared is 34.63 MPa, the flexural strength is 544.62 MPa, and the tensile strength is 620.23 MPa.

[0075] Comparative Example 1

[0076] A method for producing a special-shaped continuous fiber prepreg for 3D printing is basically the same as Example 1, except that the special-shaped die in Example 1 is replaced by a die with a circular cross-section and a diameter of 0.8 mm.

[0077] A method for preparing a composite material is basically the same as Example 1, except that the special-shaped continuous fiber prepreg for 3D printing in Example 1 is replaced by the special-shaped continuous fiber prepreg for 3D printing prepared in Comparative Example 1.

[0078] The composite material finally obtained had an interlaminar shear strength of 24.09 MPa, a flexural strength of 301.93 MPa, and a tensile strength of 535.65 MPa.

[0079] Compared with Example 1, the interlaminar shear strength, bending strength and tensile strength of Comparative Example 1 are not as good as those of Example 1. This is because the continuous fiber prepreg with a special-shaped cross-section has a larger surface area when it is in-situ combined with the thermoplastic filament during the 3D printing process, and can be more fully integrated with the matrix material, effectively enhancing the matrix-matrix interface and matrix-fiber interface of the 3D printed product, thereby effectively enhancing the mechanical properties of the product.

[0080] Comparative Example 2

[0081] A method for preparing a composite material is basically the same as that in Example 1, except that the special-shaped continuous fiber prepreg for 3D printing in the raw material in Example 1 is replaced by the continuous fiber bundle in step (1) in Example 1.

[0082] The interlaminar shear strength of the composite material finally prepared is 16.21 MPa, the flexural strength is 229.32 MPa, and the tensile strength is 279.53 MPa.

[0083] Compared with Example 1, the layer shear strength, bending strength and tensile strength of Comparative Example 2 are not as good as those of Example 1. This is because ordinary fiber bundles cannot be effectively impregnated with the resin, so it is difficult for the 3D printed composite material to have an interface bonding between the fiber and the matrix, resulting in poor mechanical properties of the product.

[0084] Comparative Example 3

[0085] A method for producing a special-shaped continuous fiber prepreg for 3D printing is basically the same as that in Example 1, except that l is 0.2 mm (ie, l<π×d / n).

[0086] A method for preparing a composite material is basically the same as Example 1, except that the special-shaped continuous fiber prepreg for 3D printing in Example 1 is replaced by the special-shaped continuous fiber prepreg for 3D printing prepared in Comparative Example 3.

[0087] The composite material finally obtained had an interlaminar shear strength of 19.75 MPa, a flexural strength of 373.28 MPa, and a tensile strength of 405.21 MPa.

[0088] Compared with Example 1, the interlaminar shear strength, bending strength and tensile strength of Comparative Example 3 are not as good as those of Example 1. This is because although the continuous fiber prepreg at this time has a special-shaped cross-section, due to l<π×d / n, its surface area is not significantly larger than that of the ordinary prepreg with a circular cross-section. Therefore, during the 3D printing process, the contact area is reduced when it is in-situ combined with the thermoplastic filament, which is not conducive to the fusion of the matrix material and the special-shaped continuous fiber prepreg, and the matrix-matrix interface and matrix-fiber interface of the 3D printed product cannot be effectively enhanced, thereby failing to effectively enhance the mechanical properties of the product.

[0089] Example 2

[0090] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0091] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.4mm, and d is 0.6mm;

[0092] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 45 mm, and the vertical distance is 5 mm;

[0093] Along the fiber running direction, the cooler is located in front of the melt impregnation tank outlet, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the melt impregnation tank outlet and the cooler is 1 cm;

[0094] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 5 cm; the rotation speed of the first reel and the second reel is 2 mm / s.

[0095] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0096] (1) Preparation of raw materials;

[0097] Resin: polyetheretherketone with a melt index of 4.7 g / 10 min at a temperature of 350°C and a load of 2.16 kg;

[0098] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0099] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0100] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 19N;

[0101] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 350° C.;

[0102] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0103] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0104] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0105] The above-mentioned special-shaped continuous fiber prepreg and polyetheretherketone wire (manufacturer is Victrex, brand name is Victrex-450G) for 3D printing are used as raw materials to prepare composite materials by 3D printing. The specific printing process is as follows: the thermoplastic wire (polyetheretherketone wire) and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 420°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0106] The interlaminar shear strength of the composite material finally prepared is 38.93 MPa, the flexural strength is 602.15 MPa, and the tensile strength is 680.32 MPa.

[0107] Example 3

[0108] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0109] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 12, l is 0.6 mm, and d is 0.6 mm;

[0110] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 45 mm, and the vertical distance is 5 mm;

[0111] Along the fiber running direction, the cooler is located in front of the melt impregnation tank outlet, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the melt impregnation tank outlet and the cooler is 1 cm;

[0112] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 5 cm; the rotation speed of the first reel and the second reel is 2 mm / s.

[0113] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0114] (1) Preparation of raw materials;

[0115] Resin: polyetherketoneketone with a melt index of 4.7 g / 10 min at 350°C and a load of 2.16 kg;

[0116] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0117] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0118] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 17N;

[0119] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 350° C.;

[0120] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0121] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0122] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0123] The above-mentioned special-shaped continuous fiber prepreg and polyetherketoneketone filament (manufacturer: Arkema, brand: Kepstan-7002) for 3D printing are used as raw materials to prepare composite materials by 3D printing. The specific printing process is as follows: the thermoplastic filament (polyetherketoneketone filament) and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 375°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0124] The composite material finally obtained had an interlaminar shear strength of 37.63 MPa, a flexural strength of 632.51 MPa, and a tensile strength of 675.85 MPa.

[0125] Example 4

[0126] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0127] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.25mm, and d is 0.6mm;

[0128] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 45 mm, and the vertical distance is 5 mm;

[0129] Along the fiber running direction, the cooler is located in front of the melt impregnation tank outlet, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the melt impregnation tank outlet and the cooler is 1 cm;

[0130] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 5 cm; the rotation speed of the first reel and the second reel is 2 mm / s.

[0131] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0132] (1) Preparation of raw materials;

[0133] Resin: Polyetherimide with a melt index of 5.8 g / 10 min at a temperature of 320°C and a load of 2.16 kg;

[0134] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0135] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0136] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 15N;

[0137] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 320° C.;

[0138] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0139] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0140] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0141] The above-mentioned special-shaped continuous fiber prepreg and polyetherimide wire (manufacturer is SABIC, brand is Ultem-1000) for 3D printing are used as raw materials to prepare composite materials by 3D printing. The specific printing process is as follows: the thermoplastic wire (polyetherimide wire) and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 350°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0142] The interlaminar shear strength of the composite material finally prepared is 33.56 MPa, the flexural strength is 565.68 MPa, and the tensile strength is 598.32 MPa.

[0143] Example 5

[0144] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0145] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.4mm, and d is 0.6mm;

[0146] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 55 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 75 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 45 mm, and the vertical distance is 5 mm;

[0147] Along the fiber running direction, the cooler is located in front of the melt impregnation tank outlet, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the melt impregnation tank outlet and the cooler is 1 cm;

[0148] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 5 cm; the rotation speed of the first reel and the second reel is 2 mm / s.

[0149] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0150] (1) Preparation of raw materials;

[0151] Resin: polyvinylidene fluoride with a melt index of 7.1 g / 10 min at 240°C and a load of 2.16 kg;

[0152] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0153] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0154] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 14N;

[0155] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 240°C;

[0156] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0157] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0158] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0159] The above-mentioned special-shaped continuous fiber prepreg and polyvinylidene fluoride wire for 3D printing (manufacturer is 3DXTECH, brand is FluorX TM PVDF) is used as a raw material to prepare a composite material by 3D printing. The specific printing process is: thermoplastic wire (polyvinylidene fluoride wire) and profiled continuous fiber prepreg enter a heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Driven by a driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on a heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 275°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0160] The interlaminar shear strength of the composite material finally prepared is 31.24MPa, the flexural strength is 415.85MPa, and the tensile strength is 398.32MPa.

[0161] Example 6

[0162] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0163] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 12, l is 0.6 mm, and d is 0.6 mm;

[0164] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 50 mm, and the vertical distance is 5 mm;

[0165] Along the fiber running direction, the cooler is located in front of the outlet of the melt impregnation tank, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the outlet of the melt impregnation tank and the cooler is 3 cm;

[0166] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 10 cm; the rotation speed of the first reel and the second reel is 8 mm / s.

[0167] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0168] (1) Preparation of raw materials;

[0169] Resin: Melt index is 10.3 g / 10 min at 200°C and 2.16 kg load;

[0170] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0171] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0172] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 14N;

[0173] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and when the amount of resin added is close to the capacity limit of the melt impregnation tank, turn on the traction machine; wherein the temperature of the resin melt is 200° C.;

[0174] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0175] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0176] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0177] The above-mentioned special-shaped continuous fiber prepreg and polylactic acid filament for 3D printing (manufacturer: 3DXTECH, brand: The invention relates to a composite material prepared by 3D printing using polylactic acid (PLA) as raw material. The specific printing process is as follows: the thermoplastic wire (polylactic acid wire) and the profiled continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the push of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare the 3D printed composite material. In this process, the 3D printing temperature is set to 230°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain the composite material.

[0178] The interlaminar shear strength of the composite material finally prepared is 28.73 MPa, the flexural strength is 468.57 MPa, and the tensile strength is 556.79 MPa.

[0179] Example 7

[0180] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0181] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.25mm, and d is 0.6mm;

[0182] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 50 mm, and the vertical distance is 5 mm;

[0183] Along the fiber running direction, the cooler is located in front of the outlet of the melt impregnation tank, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the outlet of the melt impregnation tank and the cooler is 3 cm;

[0184] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 10 cm; the rotation speed of the first reel and the second reel is 8 mm / s.

[0185] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0186] (1) Preparation of raw materials;

[0187] Resin: Polyamide 66 with a melt index of 12.4 g / 10 min at 200°C and a load of 2.16 kg;

[0188] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0189] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0190] (3) The continuous fiber bundle is sequentially passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank to form a "V" shape in the melt impregnation tank, and then sequentially passes through the special-shaped die, the melt impregnation tank outlet, and the cooler to be fixed between the first reel and the second reel in the traction machine to form a tension of 11N;

[0191] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and when the amount of resin added is close to the capacity limit of the melt impregnation tank, turn on the traction machine; wherein the temperature of the resin melt is 200° C.;

[0192] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0193] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0194] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0195] The above-mentioned special-shaped continuous fiber prepreg and polyamide 66 wire (manufacturer is 3DXTECH, brand name is AmideX TM Nylon66) is used as a raw material to perform 3D printing to prepare a composite material. The specific printing process is as follows: thermoplastic wire (polyamide 66 wire) and profiled continuous fiber prepreg enter a heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Driven by a driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on a heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 220°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0196] The interlaminar shear strength of the composite material finally obtained is 33.28 MPa, the flexural strength is 536.89 MPa, and the tensile strength is 605.66 MPa.

[0197] Example 8

[0198] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0199] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 8, l is 0.4mm, and d is 0.6mm;

[0200] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 65 mm, and the vertical distance is 75 mm; the horizontal distance between the second dipping roller and the third dipping roller is 65 mm, and the vertical distance is 75 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 85 mm, and the vertical distance is 65 mm; the horizontal distance between the special-shaped die and the third dipping roller is 55 mm, and the vertical distance is 5 mm;

[0201] Along the fiber running direction, the cooler is located in front of the outlet of the melt impregnation tank, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the outlet of the melt impregnation tank and the cooler is 2 cm;

[0202] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 9.5 cm; the rotation speed of the first reel and the second reel is 7 mm / s.

[0203] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0204] (1) Preparation of raw materials;

[0205] Resin: Acrylonitrile-butadiene-styrene with a melt index of 13.5 g / 10 min at 190°C and a load of 2.16 kg;

[0206] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0207] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0208] (3) The continuous fiber bundle is passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank in sequence, so that the continuous fiber bundle forms a "V" shape in the melt impregnation tank, and then passes through the special-shaped die, the melt impregnation tank outlet, and the cooler in sequence and is fixed between the first reel and the second reel in the traction machine to form a tension of 7N;

[0209] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 190° C.;

[0210] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0211] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0212] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0213] The above-mentioned special-shaped continuous fiber prepreg and acrylonitrile-butadiene-styrene wire for 3D printing (manufacturer: 3DXTECH, brand: ABS) is used as a raw material to prepare a composite material by 3D printing. The specific printing process is: thermoplastic wire (acrylonitrile-butadiene-styrene wire) and profiled continuous fiber prepreg enter a heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Driven by a driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on a heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 210°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0214] The composite material finally obtained had an interlaminar shear strength of 25.68 MPa, a flexural strength of 445.12 MPa, and a tensile strength of 505.29 MPa.

[0215] Example 9

[0216] A production device for special-shaped continuous fiber prepreg for 3D printing, comprising a fiber reel, a melt impregnation tank, a cooler and a tractor;

[0217] The outside of the melt impregnation tank is provided with a fiber bundle limiting hole connected to the melt impregnation tank inlet for the continuous fiber bundle to pass through, the inside is provided with a heater, a continuous fiber bundle tensioning mechanism and a special-shaped die connected to the melt impregnation tank outlet, and a thermoplastic resin feeder is provided on the top; the special-shaped die is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; n is 12, l is 0.8 mm, and d is 0.6 mm;

[0218] The continuous fiber bundle tensioning mechanism consists of a first dipping roller, a second dipping roller and a third dipping roller arranged in sequence along the fiber running direction. The second dipping roller is located between the first dipping roller and the third dipping roller and below the first and third dipping rollers; the horizontal distance between the first dipping roller and the second dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the second dipping roller and the third dipping roller is 60 mm, and the vertical distance is 80 mm; the horizontal distance between the fiber bundle limiting hole and the first dipping roller is 80 mm, and the vertical distance is 60 mm; the horizontal distance between the special-shaped die and the third dipping roller is 50 mm, and the vertical distance is 5 mm;

[0219] Along the fiber running direction, the cooler is located in front of the outlet of the melt impregnation tank, and the cooler is provided with a first cooling fan and a second cooling fan; the horizontal distance between the outlet of the melt impregnation tank and the cooler is 3 cm;

[0220] Along the fiber running direction, the traction machine is located in front of the cooler, and the traction machine is provided with a first reel and a second reel; the horizontal distance between the cooler and the traction machine is 10 cm; the rotation speed of the first reel and the second reel is 9 mm / s.

[0221] A method for producing a special-shaped continuous fiber prepreg for 3D printing using the above device comprises the following specific steps:

[0222] (1) Preparation of raw materials;

[0223] Resin: Polypropylene with a melt index of 10.3 g / 10 min at 180°C and a load of 2.16 kg;

[0224] Continuous fiber bundle: a carbon fiber bundle with 1000 filaments and a diameter (i.e. d) of 0.6 mm;

[0225] (2) The continuous fiber bundle is pulled out from the fiber reel by a threading needle, passes through the fiber bundle limiting holes in sequence, and then enters the entrance of the melt impregnation tank;

[0226] (3) The continuous fiber bundle is sequentially passed through the first dipping roller, the second dipping roller, and the third dipping roller in the melt impregnation tank to form a "V" shape in the melt impregnation tank, and then sequentially passes through the special-shaped die, the melt impregnation tank outlet, and the cooler to be fixed between the first reel and the second reel in the traction machine to form a tension of 8N;

[0227] (4) Turn on the heater of the melt impregnation tank, adjust the temperature to the temperature of the meltable resin (i.e., the temperature of the resin melt), add the resin to the feed port of the thermoplastic resin feeder, and turn on the traction machine when the amount of resin added is close to the capacity limit of the melt impregnation tank; wherein the temperature of the resin melt is 180° C.;

[0228] (5) When the resin melt appears on the surface of the continuous fiber bundle drawn out from the molten impregnation tank, the cooler is turned on to rotate the first cooling fan and the second cooling fan at a high speed to cool the resin melt and form a continuous fiber bundle with a special-shaped cross-section, i.e., a special-shaped continuous fiber prepreg for 3D printing;

[0229] The immersion time of the continuous fiber bundle in the molten impregnation tank is t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; v is in mm / s, which is the same as the rotation speed of the first reel and the second reel.

[0230] The final prepared special-shaped continuous fiber prepreg for 3D printing consists of continuous fiber bundles and resin.

[0231] The above-mentioned special-shaped continuous fiber prepreg and polypropylene filament for 3D printing (manufacturer is 3DXTECH, brand name is HyperLite TM PP) is used as a raw material to perform 3D printing to prepare a composite material. The specific printing process is as follows: thermoplastic wire (polypropylene wire) and profiled continuous fiber prepreg enter a heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Driven by a driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on a heated base plate together with the profiled continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material. In this process, the 3D printing temperature is set to 200°C, the layer thickness is 0.2mm, the routing distance is 0.5mm, and the printing speed is 2mm / s, and then 3D printing is performed to obtain a composite material.

[0232] The composite material finally obtained had an interlaminar shear strength of 25.39 MPa, a flexural strength of 455.45 MPa, and a tensile strength of 549.61 MPa.

Claims

1. A method for producing a special-shaped continuous fiber prepreg for 3D printing, characterized in that: The continuous fiber bundle is impregnated in a resin melt, passed through a special-shaped die, and then cooled to obtain a special-shaped continuous fiber prepreg for 3D printing; The special-shaped die is a die with a regular star-shaped cross section, the regular star-shaped is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, l>π×d / n; The above-mentioned special-shaped continuous fiber prepreg and polyamide 6 wire for 3D printing are used as raw materials to prepare composite materials by 3D printing. The specific printing process is as follows: the polyamide 6 wire and the special-shaped continuous fiber prepreg enter the heating nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the push of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare the 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 34.63MPa, the bending strength is 544.62MPa, and the tensile strength is 620.23MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polyetheretherketone wire for 3D printing are used as raw materials to perform 3D printing to prepare a composite material. The specific printing process is: the polyetheretherketone wire and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 38.93MPa, the bending strength is 602.15MPa, and the tensile strength is 680.32MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polyetherketoneketone filament for 3D printing are used as raw materials to prepare a composite material by 3D printing. The specific printing process is: the polyetherketoneketone filament and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 37.63MPa, the bending strength is 632.51MPa, and the tensile strength is 675.85MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polyetherimide wire for 3D printing are used as raw materials to prepare a composite material by 3D printing. The specific printing process is: the polyetherimide wire and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 33.56MPa, the bending strength is 565.68MPa, and the tensile strength is 598.32MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polyvinylidene fluoride wire for 3D printing are used as raw materials to prepare a composite material by 3D printing. The specific printing process is: the polyvinylidene fluoride wire and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 31.24MPa, the bending strength is 415.85MPa, and the tensile strength is 398.32MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polylactic acid wire for 3D printing are used as raw materials to prepare a composite material by 3D printing. The specific printing process is: the polylactic acid wire and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 28.73MPa, the bending strength is 468.57MPa, and the tensile strength is 556.79MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polyamide 66 wire for 3D printing are used as raw materials to prepare a composite material by 3D printing. The specific printing process is as follows: the polyamide 66 wire and the special-shaped continuous fiber prepreg enter the heated nozzle with double feed ports at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 33.28MPa, the bending strength is 536.89MPa, and the tensile strength is 605.66MPa; Alternatively, the above-mentioned shaped continuous fiber prepreg and acrylonitrile-butadiene-styrene wire for 3D printing are used as raw materials to perform 3D printing to prepare a composite material. The specific printing process is as follows: the acrylonitrile-butadiene-styrene wire and the shaped continuous fiber prepreg enter a heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the interlaminar shear strength of the composite material finally obtained is 25.68MPa, the bending strength is 445.12MPa, and the tensile strength is 505.29MPa; Alternatively, the above-mentioned special-shaped continuous fiber prepreg and polypropylene wire for 3D printing are used as raw materials to carry out 3D printing to prepare a composite material. The specific printing process is: the polypropylene wire and the special-shaped continuous fiber prepreg enter the heated nozzle with a double feed port at the same time, and are combined from the nozzle before extrusion to achieve in-situ impregnation. Under the drive of the driving gear, the molten thermoplastic resin is extruded from the nozzle and deposited on the heated base plate together with the special-shaped continuous fiber prepreg, and then deposited layer by layer to prepare a 3D printed composite material; the final composite material has an interlaminar shear strength of 25.39 MPa, a flexural strength of 455.45 MPa, and a tensile strength of 549.61 MPa.

2. The method for producing a special-shaped continuous fiber prepreg for 3D printing according to claim 1, characterized in that: The resin is polyetheretherketone or polyetherketoneketone with a melt index of ≤5g / 10min at a temperature of 350°C and a load of 2.16kg, or polyetherimide with a melt index of >5g / 10min and ≤10g / 10min at a temperature of 320°C and a load of 2.16kg, or polyvinylidene fluoride with a melt index of >5g / 10min and ≤10g / 10min at a temperature of 240°C and a load of 2.16kg, or ℃ and a load of 2.16kg, polylactic acid having a melt index >10g / 10min at a temperature of 200℃ and a load of 2.16kg, or polyamide having a melt index >10g / 10min at a temperature of 200℃ and a load of 2.16kg, or acrylonitrile-butadiene-styrene having a melt index >10g / 10min at a temperature of 190℃ and a load of 2.16kg, or polypropylene having a melt index >10g / 10min at a temperature of 180℃ and a load of 2.16kg.

3. The method for producing a special-shaped continuous fiber prepreg for 3D printing according to claim 2, characterized in that: When the resin is polyetheretherketone, polyetherketoneketone or polyetherimide, the temperature of the resin melt is 320-350°C; when the resin is polyamide or polyvinylidene fluoride, the temperature of the resin melt is 200-250°C; when the resin is polylactic acid, polypropylene or acrylonitrile-butadiene-styrene, the temperature of the resin melt is 180-200°C.

4. The method for producing a special-shaped continuous fiber prepreg for 3D printing according to claim 2, characterized in that: When the resin is polyetheretherketone, polyetherketoneketone or polyetherimide, the tension of the continuous fiber bundle during impregnation is 15 to 20N; when the resin is polylactic acid, polyamide or polyvinylidene fluoride, the tension of the continuous fiber bundle during impregnation is 10 to 15N; when the resin is polypropylene or acrylonitrile-butadiene-styrene, the tension of the continuous fiber bundle during impregnation is 5 to 10N.

5. The method for producing a special-shaped continuous fiber prepreg for 3D printing according to claim 2, characterized in that: The impregnation time t=L / v; L is the length of the continuous fiber bundle immersed in the resin melt, in mm; the unit of v is mm / s; when the resin is polyetheretherketone or polyetherketoneketone, v is 2 mm / s; when the resin is polyetherimide or polyvinylidene fluoride, v is 2-6 mm / s; when the resin is polylactic acid, polyamide, acrylonitrile-butadiene-styrene or polypropylene, v is 6-10 mm / s.

6. The method for producing a special-shaped continuous fiber prepreg for 3D printing according to claim 1, characterized in that: The continuous fiber bundle is a carbon fiber bundle having 1,000 filaments.

7. A device for realizing a method for producing a special-shaped continuous fiber prepreg for 3D printing as claimed in any one of claims 1 to 6, characterized in that: The invention comprises a melt impregnation tank, the outside of which is provided with a fiber bundle limiting hole (3) connected to an inlet (4-1) of the melt impregnation tank and for allowing a continuous fiber bundle to pass through, the inside of which is provided with a heater and a special-shaped die (4-5) connected to an outlet (4-6) of the melt impregnation tank, and the top of which is provided with a thermoplastic resin feeder (5); the special-shaped die (4-5) is a die with a regular star-shaped cross section, the regular star shape is an n-sided polygon with a side length of l, the diameter of the continuous fiber bundle is d, and l>π×d / n.

8. The device according to claim 7, characterized in that There is also a continuous fiber bundle tensioning mechanism inside the melt impregnation tank.

9. The device according to claim 8, characterized in that The continuous fiber bundle tensioning mechanism consists of a first dipping roller (4-2), a second dipping roller (4-3) and a third dipping roller (4-4) which are sequentially arranged along the fiber running direction, wherein the second dipping roller (4-3) is located between the first dipping roller (4-2) and the third dipping roller (4-4) and below the first dipping roller (4-2) and the third dipping roller (4-4); the horizontal distance between the first dipping roller (4-2) and the second dipping roller (4-3) is 60±5mm, and the vertical distance is 80±5mm; the horizontal distance between the second dipping roller (4-3) and the third dipping roller (4-4) is 60±5mm, and the vertical distance is 80±5mm; the horizontal distance between the fiber bundle limiting hole (3) and the first dipping roller (4-2) is 80±5mm, and the vertical distance is 60±5mm; the horizontal distance between the special-shaped die (4-5) and the third dipping roller (4-4) is 50±5mm, and the vertical distance is 5±1mm.

10. The device according to claim 7, characterized in that It also includes a cooler (6) located in front of the melt impregnation tank outlet (4-6) along the fiber running direction, and a first cooling fan (6-1) and a second cooling fan (6-2) are arranged in the cooler (6); The horizontal distance between the outlet of the molten immersion tank (4-6) and the cooler (6) is 1 to 3 cm.

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