Continuous fiber-reinforced 3d printed filament forming device and method

Abstract

The application provides a continuous fiber reinforced 3D printing filament forming device and method. The device comprises an upper mold, a lower mold, a positioning device, a heating device and a base. The upper and lower molds are provided with double curvature grooves on the surfaces and are relatively rotatable. The relative rotation of the molds is driven by the positioning device, so as to change the effective cross-sectional size of the material forming channel formed by the grooves of the two molds. The method comprises the following steps: preheating the device and setting the initial angle of the mold; feeding the material containing continuous fibers into the channel for preforming trial production; then adjusting the angle of the mold to reduce the size of the channel according to the forming effect, so that the preformed filament realizes deep impregnation and densification, and finally high-quality filament is obtained. The application solves the problems of the traditional fixed mouth mold, such as the inability to adjust online, poor adaptability and process flexibility. The application can significantly optimize the impregnation effect of the resin on the fiber, reduce the porosity of the filament, and realize flexible and accurate control of the filament diameter. The application is suitable for the preparation of high-performance continuous fiber reinforced 3D printing filament.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and more specifically, to a continuous fiber reinforced 3D printing filament forming apparatus and method. Background Technology

[0002] Resin-based composite materials possess advantages such as high specific strength, high specific modulus, strong designability, and ease of integral molding, leading to their widespread application in aerospace, transportation, energy, and communications. Among the numerous molding processes for resin-based composite materials, additive manufacturing technology, represented by 3D printing, is attracting increasing attention due to its unique advantages, including high material utilization, strong designability, ability to achieve integrated molding of complex structures, and the elimination of the need for separate molds. In particular, compared to chopped fiber systems, continuous fiber 3D printed composite materials exhibit higher mechanical properties and a wider range of applications, making them one of the key research and application directions. Continuous fiber reinforced 3D printing filaments have become a crucial material foundation in this technological field.

[0003] The core raw material for continuous fiber 3D printing technology is continuous fiber filament pre-impregnated with resin. The quality of this filament directly determines the performance of the final printed part. High-quality filament requires the fibers to be fully impregnated in the resin matrix, evenly distributed, with low porosity, and a stable and consistent filament diameter. Currently, the conventional method for preparing such filaments mainly relies on extrusion molding using a die of a fixed size. However, this method has significant limitations: for materials with different fiber contents, resin viscosities, or target filament diameters, different dies of different sizes need to be changed, resulting in poor flexibility, long adjustment cycles, and high costs; furthermore, the extrusion and impregnation process of a single-sized die during molding is fixed, making it difficult to optimize the impregnation effect and density through dynamic adjustment. Summary of the Invention

[0004] (a) Technical problems to be solved The technical problem to be solved by the present invention is that the die of the continuous fiber reinforced 3D printing filament forming device is fixed, cannot be adjusted online, and has poor process flexibility.

[0005] (II) Technical Solution To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a continuous fiber reinforced 3D printing filament forming apparatus, comprising an upper mold, a lower mold, a positioning device, a heating device, and a base; the upper mold and the lower mold are rotatably connected to the base, the upper mold and the lower mold have the same structure and are arranged opposite to each other, and their rotation axes are parallel; two positioning devices are respectively connected to the upper mold and the lower mold, and are used to drive and control the rotation angle of the upper mold and the lower mold; the heating device is used to heat the upper mold and the lower mold; wherein, the surfaces of the upper mold and the lower mold are provided with double-curvature grooves for material to pass through, and the positioning device drives the upper mold and the lower mold to rotate relative to each other to change the effective cross-sectional size of the double-curvature groove through which the material passes.

[0006] Specifically, the upper mold and the lower mold have identical structures and are mirror-symmetrical or arranged opposite each other. Both are rotatably connected to the base, and their rotation axes are parallel to each other. A double-curvature groove is formed on the opposing surfaces (i.e., the faces of opposite parts) of the upper and lower molds. The positioning devices (usually two, such as a servo motor with a precision reducer) are connected to the upper and lower molds respectively, for independently or synchronously driving and precisely controlling their rotation angles. The heating device (such as a heating rod, heating jacket, or hot oil circulation system) is integrated into the base or arranged around the molds, for heating the upper and lower molds to maintain the material passing through them at a suitable processing temperature. The base is used to fix and support all the above components.

[0007] The core of this invention lies in the fact that by driving the upper and lower molds to rotate relative to each other through the positioning device (like two cylinders rotating in opposite directions), the effective cross-sectional size and shape of the material forming channel formed by the two hyperboloid grooves coming together can be changed. Different rotation angles result in changes in the equivalent diameter and compression ratio of the material forming channel, thereby achieving the goal of adjusting the forming size online without replacing the physical mold.

[0008] Preferably, the cross-section of the hyperbolic groove is a semi-circular or U-shaped section with a gradually changing diameter. This hyperbolic groove can compress, shape, and densify the material as it passes through. The cross-sectional diameter of the hyperbolic groove varies at different locations, making it suitable for forming 3D printing filaments of different sizes. The diameter of the hyperbolic groove is smallest at one end along its length, ranging from 0.1 to 1.0 mm, and largest at the other end, ranging from 0.2 to 5.0 mm. The included angle α between the centers of the smallest and largest cross-sections of the groove is 45 to 330°. This structure allows different diameter sections of the hyperbolic groove to participate in forming a channel when the mold rotates, thereby achieving continuous change in the channel size. When the upper and lower molds rotate around the axis, the material's own position remains unchanged, but the relative position of the material and the hyperbolic groove changes. That is, the cross-sectional size of the hyperbolic groove through which the material passes changes, achieving online control of the 3D printing filament diameter.

[0009] Preferably, the positioning device is capable of driving the upper mold and the lower mold to rotate by an angle β, where 45°≤β≤α. That is, the rotation range covers the entire effective working range of the hyperbolic groove.

[0010] Preferably, the radial distance from the center of any cross-section of the hyperbolic groove to the rotation axis of the corresponding mold is the same, and the radial distance is 5~100mm. This is the key geometric feature for realizing the rotary diameter change function: when the mold rotates around its axis, the trajectory of the center of the hyperbolic groove is a circle of fixed radius, thereby ensuring that the centerline position of the material remains stable when it passes through, and is only squeezed by the channel wall without lateral displacement.

[0011] Preferably, the upper mold and the lower mold are arranged vertically opposite each other, and the double-curvature grooves of the upper mold and the lower mold together form a closed material forming channel for material to pass through. This method results in uniform forming pressure and good wire roundness.

[0012] Preferably, the upper and lower molds are arranged alternately along the material's travel direction, with the material sequentially passing through the double-curvature grooves of the upper and lower molds. This allows the material to be shaped by passing through the upper and lower molds sequentially, reducing the risk of mold blockage and ensuring good production continuity. The alternating arrangement essentially extends the material's travel path and time under controlled heating and extrusion. This provides more sufficient conditions and time for the resin to more fully and uniformly impregnate the continuous fiber bundles, and for the removal of air bubbles from within the material. The longer processing path more effectively overcomes the poor flowability of high-viscosity resins, better achieving resin encapsulation and wetting of fibers in high-fiber-content materials.

[0013] Preferably, the heating temperature of the heating device is T≥T0, where T0 is the processing temperature of the material. More preferably, the heating temperature of the heating device is T≥T0+50℃. This is used to melt and soften the material to ensure that the mold temperature is sufficient to maintain good fluidity of the material so that it can be smoothly shaped and compacted when passing through the mold.

[0014] Secondly, the present invention also provides a method for forming continuous fiber reinforced 3D printing filaments, which is implemented using a continuous fiber reinforced 3D printing filament forming device, and the method includes the following steps: S1. Preheat the continuous fiber reinforced 3D printing filament forming device and adjust the upper mold and the lower mold to the initial angle; adjust the upper and lower molds to an initial angle (usually corresponding to a larger channel size) using the positioning device.

[0015] S2. The material containing continuous fibers (such as fiber / resin mixture from an extruder or prepreg tape) is fed into the continuous fiber reinforced 3D printing filament forming device, so that the material passes sequentially through the material forming channel formed by the double curvature groove of the upper mold and the double curvature groove of the lower mold to obtain the trial-produced preformed filament. S3. Based on the forming condition of the preformed filament, the rotation angles of the upper and lower molds are adjusted using the positioning device to reduce the effective cross-sectional size of the material forming channel, further densifying the preformed filament and obtaining a continuous fiber-reinforced 3D printing filament. This process further compresses, shears, and shapes the filament, forcing the resin to more fully impregnate the fiber bundles, expel air bubbles, and increase density, thereby obtaining a high-quality continuous fiber-reinforced 3D printing filament. This step can be repeated or performed dynamically as needed.

[0016] S4. Detect the parameters of the continuous fiber reinforced 3D printing filament obtained in step S3. If the parameters meet the requirements, proceed to step S5. If the parameters do not meet the requirements, repeat step S3 until the parameters meet the requirements. S5. Cooling (usually by air cooling or water cooling tank) and collecting the continuous fiber reinforced 3D printing filament.

[0017] Preferably, the material is a mixture of continuous fibers (such as carbon fiber, glass fiber, aramid fiber, etc.) and resin (such as PLA, ABS, PA, PEEK, etc.), or the material is a continuous fiber reinforced resin matrix composite preform (such as prepreg yarn, prepreg tape).

[0018] Preferably, the parameters include: porosity not exceeding 3% and continuous fiber volume content of 20-75%.

[0019] (III) Beneficial Effects The above-described technical solution of the present invention has at least the following advantages: 1. This invention can continuously and precisely change the size of the material forming channel by rotating the upper and lower molds without stopping the machine to change the die, which greatly improves the flexibility and efficiency of production and can quickly adapt to the production needs of different wire diameter specifications or different material formulas.

[0020] 2. This invention employs a pre-forming + secondary (or multiple) variable cross-section extrusion process, providing more sufficient conditions for resin impregnation of fibers and elimination of pores. By dynamically adjusting the channel size, the extrusion shear force can be controlled, thereby optimizing the impregnation process, effectively reducing the porosity of the filament, and improving product quality.

[0021] 3. The device provided by this invention has good structural rigidity and high positioning accuracy, which can ensure precise control and long-term stability of the forming channel size, thereby guaranteeing the uniformity of wire diameter and roundness. The core diameter changing mechanism is realized through simple rotational motion, with a simple and compact mechanical structure, few moving parts, easy manufacturing, maintenance and control, and reliable operation. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the continuous fiber reinforced 3D printing filament forming device provided in an embodiment of the present invention.

[0024] Figure 2 These are three views of the upper mold provided in an embodiment of the present invention.

[0025] The labels for the attached figures are as follows: 1. Upper mold; 2. Lower mold; 3. Positioning device; 4. Heating device; 5. Base; 6. Rotating shaft; 7. Material; 11. Double curvature groove; 12. First end; 13. Second end. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0028] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments: See Figure 1 and Figure 2 This embodiment provides a continuous fiber reinforced 3D printing filament forming device, which includes a base 5, an upper mold 1, a lower mold 2, a positioning device 3, and a heating device 4. The base 5 is a sturdy frame used to support all components. The upper mold 1 and the lower mold 2 are two cylindrical molds with identical structural dimensions, placed vertically opposite each other. Each mold is rotatably mounted on the base 5 via pivots 6 at both ends, and the pivot axes of the upper mold 1 and the lower mold 2 are parallel.

[0030] A special hyperbolic groove 11 is machined along the axial direction on the outer surface of the cylinders of the upper mold 1 and the lower mold 2. For example... Figure 2 As shown, the cross-section of the hyperbolic groove 11 is semi-circular. The key feature is that, firstly, from the first end 12 to the second end 13 of the upper mold 1 / lower mold 2, the diameter of the semi-circular cross-section of the hyperbolic groove 11 gradually changes, with the first end 12 having the smallest diameter D. min (e.g., 0.4mm), the second end 13 is the maximum diameter D. max (For example, 2.0 mm), the central angle α between the first end 12 and the second end 13 is 100°. Secondly, the radial distance R from the center of the semicircle at any cross-section of the hyperbolic groove 11 to the center line of the mold's own rotation axis 6 is constant (for example, 30 mm). This means that the hyperbolic groove 11 is a manifestation of a "gradually changing cross-section spiral groove with equal radius" on a cylindrical surface.

[0031] The positioning device 3 uses two high-precision servo motors, which are connected to the ends of the rotating shafts 6 of the upper mold 1 and the lower mold 2 respectively via couplings, and can independently control the rotation angle and speed of each mold. The heating device 4 consists of a heating rod and a temperature control system embedded in the base 5, which can accurately heat and maintain the temperature of the mold.

[0032] During operation, the double-curvature grooves 11 of the upper mold 1 and the lower mold 2 face each other, forming a complete, approximately circular material forming channel. By driving the molds to rotate via a servo motor, the cross-sectional position of the double-curvature grooves involved in forming the material forming channel can be changed. When the mold is in its initial position (β=0°), channel 8 is formed by the larger diameter double-curvature groove portion, resulting in a thicker channel. When the molds are rotated relative to each other by an angle β (e.g., 90°), the double-curvature groove portion involved in forming the material forming channel moves towards the smaller diameter end, thus reducing the effective diameter of channel 8. By controlling the rotation angle β through a program, the channel size can be adjusted online and steplessly.

[0033] Example 1: like Figure 1 As shown, the continuous fiber reinforced 3D printing filament forming device of the present invention has an upper mold 1 and a lower mold 2 with identical structures. The cross-section of the double curvature groove 11 of the upper mold 1 is a semi-circle with a uniformly varying diameter. The first end 12 has the smallest diameter (0.2 mm), and the second end 13 has the largest diameter (1.1 mm). The included angle between the smallest and largest cross-section sides of the upper mold 1 is 90° (i.e., α = 90°). The distance from the center of the semi-circle of the double curvature groove 11 to the rotating shaft 6 is the same (30 mm). The positioning device 3 controls the position and rotation angle of the upper mold 1 and the lower mold 2 by manual rotation and mechanical limiting. The rotatable angle is 90°, and the two are synchronously rotated through a linkage gear mechanism. The heating device 4 is used to heat the upper mold 1 and the lower mold 2, with a maximum heating temperature of 450°C. The base 5 is used to fix and support the upper mold 1, the lower mold 2, the positioning device 3, and the heating device 4. The upper mold 1 and the lower mold 2 are arranged parallel to each other and are arranged vertically opposite each other. The upper mold 1 is located above, allowing the material to pass through the double curvature groove 11 from below, while the lower mold 2 is located below, allowing the material to pass through the double curvature groove 11 from above.

[0034] Furthermore, the continuous fiber reinforced 3D printing filament forming method of the present invention includes the following steps: (1) Heat the continuous fiber reinforced 3D printing filament forming device to 380°C; (2) Continuous carbon fiber is used as the reinforcing fiber, and polyetheretherketone (PEEK) is used as the matrix resin. The two are premixed to obtain carbon fiber reinforced PEEK preform material, wherein the resin mass fraction is 40%; (3) Adjust the angles of the upper mold 1 and the lower mold 2 so that the material passage path passes through the maximum cross section (diameter 1.1mm) of the double curvature groove 11, and specify this position as the initial angle of the upper mold 1 and the lower mold 2; (4) The carbon fiber reinforced PEEK preform material is fed into the continuous fiber reinforced 3D printing filament forming device, so that the material passes between the double curvature groove 11 below the upper mold 1 and above the lower mold 2, with a speed of 1.0 m / min, to obtain the trial-produced preformed continuous fiber reinforced 3D printing filament (preformed filament). (5) It was observed that the preformed continuous fiber reinforced 3D printing filament could be further densified. Therefore, the upper mold 1 and the lower mold 2 were rotated by 30° to reduce the diameter of the double curvature groove 11 through which the material passage path passes to 0.8 mm, thus obtaining a further densified preformed continuous fiber reinforced 3D printing filament. (6) It was observed that the continuous fiber reinforced 3D printing filament prepared in step (5) could be further densified. Therefore, the upper mold 1 and the lower mold 2 were rotated by 10° to reduce the diameter of the mold groove through which the material passes to 0.7 mm, so as to obtain a high-quality continuous fiber reinforced 3D printing filament that is fully densified. (7) Cool and collect the product. The 3D printing filament has a diameter of 0.65~0.70 mm, a resin mass fraction of about 39%, a fiber volume fraction of about 53%, and a porosity of 1.5%.

[0035] Example 2: The continuous fiber reinforced 3D printing filament forming device of the present invention has an upper mold 1 and a lower mold 2 with identical structures. The cross-section of the double-curvature groove 11 of the upper mold 1 is a semi-circle with a uniformly varying diameter. The first end 12 has the smallest diameter (0.4 mm), and the second end 13 has the largest diameter (1.0 mm). The included angle between the smallest and largest cross-section sides of the upper mold 1 is 120°. The distance from the center of the semi-circle of the double-curvature groove 11 to the rotating shaft 6 is the same (40 mm). The positioning device 3 uses a servo motor to actively drive and control the position and rotation angle of the upper mold 1 and the lower mold 2. The rotatable angle is 120°, and the two can be controlled independently. The heating device 4 is used to heat the upper mold 1 and the lower mold 2, with a maximum heating temperature of 350°C.

[0036] The base 5 is used to fix and support the upper mold 1, lower mold 2, positioning device 3, and heating device 4. The upper mold 1 and lower mold 2 are arranged parallel to each other. The upper mold is at the top, allowing material to pass through the double-curvature groove 11 from below; the lower mold 2 is at the bottom, allowing material to pass through the double-curvature groove 11 from above. The vertical distance between their rotation axes 6 is 80mm. The upper and lower molds are arranged alternately, with the upper mold in front and the lower mold behind. The horizontal distance between their rotation axes is 40mm.

[0037] Furthermore, the continuous fiber reinforced 3D printing filament forming method of the present invention includes the following steps: (1) Heat the continuous fiber reinforced 3D printing filament forming device to 320°C; (2) Using continuous carbon fiber as the reinforcing fiber and polyphenylene sulfide (PPS) as the matrix resin, carbon fiber reinforced PPS prepreg was prepared in advance, with a resin mass fraction of 36%; (3) Adjust the angles of the upper and lower molds so that the material passage path passes through the maximum cross section (diameter of 1.0 mm) of the double curvature groove 11 of the upper and lower molds respectively, and specify this position as the initial angle of the upper and lower molds; (4) The carbon fiber reinforced PPS prepreg is fed into the 3D printing filament forming device, so that the material passes through the double curvature grooves below the upper mold and above the lower mold in succession. The speed is 1.8m / min, and the trial-produced preformed continuous fiber reinforced 3D printing filament is obtained. (5) It was observed that the preformed continuous fiber reinforced 3D printing filament could be further densified. Therefore, the upper and lower molds were rotated by 60° to reduce the diameter of the grooves in the upper and lower molds through which the material passes to 0.7 mm, thus obtaining a further densified preformed continuous fiber reinforced 3D printing filament. (6) It was observed that the continuous fiber reinforced 3D printing filament prepared in step (5) could be further densified. Therefore, the upper and lower molds were rotated by 20° to reduce the diameter of the grooves in the upper and lower molds through which the material passes to 0.6 mm, thus obtaining a further densified pre-formed continuous fiber reinforced 3D printing filament. (7) It was observed that the continuous fiber reinforced 3D printing filament prepared in step (6) could be further compacted. Therefore, the upper and lower molds were rotated by 10° to reduce the diameter of the grooves in the upper and lower molds through which the material passes to 0.55 mm, thus obtaining a fully compacted high-quality continuous fiber reinforced 3D printing filament. (8) Cool and collect the product. Tests showed that the diameter of the 3D printing filament was 0.50~0.60mm, the resin mass fraction was about 36%, the fiber volume fraction was about 56%, the porosity was 2.1%, and the continuous production length was over 1000m.

[0038] Therefore, the continuous fiber reinforced 3D printing filament forming device and forming method disclosed in this invention can achieve online precise control of the diameter of the 3D printing filament during the preparation process, and can finely adjust the filament preparation process while meeting the preparation requirements of filament products of different specifications.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous fiber-reinforced 3D printing filament forming device, characterized in that, The device includes an upper mold, a lower mold, positioning devices, a heating device, and a base. The upper mold and the lower mold are rotatably connected to the base. The upper mold and the lower mold have the same structure and are arranged opposite each other, with their rotation axes parallel. Two positioning devices are connected to the upper mold and the lower mold respectively, and are used to drive and control the rotation angle of the upper mold and the lower mold. The heating device is used to heat the upper mold and the lower mold. The upper mold and the lower mold have double-curvature grooves on their surfaces for material to pass through. The positioning device drives the upper mold and the lower mold to rotate relative to each other, thereby changing the effective cross-sectional size of the double-curvature groove through which the material passes.

2. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 1, characterized in that, The cross-section of the hyperbolic groove is a semi-circle or U-shape with a gradually changing diameter. The diameter of the hyperbolic groove is smallest at one end along its length, ranging from 0.1 to 1.0 mm, and largest at the other end, ranging from 0.2 to 5.0 mm. The included angle α between the center of the groove at the smallest and largest cross-sections is 45 to 330°.

3. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 1, characterized in that, The radial distance from the center of any cross-section of the hyperbolic groove to the rotation axis of the corresponding mold is the same, and the radial distance is 5~100mm.

4. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 1, characterized in that, The upper mold and the lower mold are arranged vertically opposite each other. The double curvature groove of the upper mold and the double curvature groove of the lower mold together form a closed material forming channel for material to pass through.

5. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 1, characterized in that, The upper mold and the lower mold are arranged alternately along the material travel direction, and the material passes through the double curvature groove of the upper mold and the double curvature groove of the lower mold in sequence.

6. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 1, characterized in that, The heating temperature of the heating device is T≥T0, where T0 is the processing temperature of the material.

7. The continuous fiber-reinforced 3D printing filament forming apparatus as described in claim 6, characterized in that, The heating temperature of the heating device is T≥T0+50℃.

8. A method for forming continuous fiber reinforced 3D printing filaments, implemented using the continuous fiber reinforced 3D printing filament forming apparatus as described in any one of claims 1-7, characterized in that, The method includes the following steps: S1. Preheat the continuous fiber reinforced 3D printing filament forming device and adjust the upper mold and the lower mold to the initial angle; S2. The material containing continuous fibers is fed into the continuous fiber reinforced 3D printing filament forming device, so that the material passes through the material forming channel formed by the double curvature groove of the upper mold and the double curvature groove of the lower mold in sequence to obtain the trial preformed filament. S3. Based on the forming condition of the preformed filament, adjust the rotation angle of the upper mold and the lower mold through the positioning device to reduce the effective cross-sectional size of the material forming channel, thereby further densifying the preformed filament and obtaining a continuous fiber reinforced 3D printing filament. S4. Detect the parameters of the continuous fiber reinforced 3D printing filament obtained in step S3. If the parameters meet the requirements, proceed to step S5. If the parameters do not meet the requirements, repeat step S3 until the parameters meet the requirements. S5. Cool and collect the continuous fiber-reinforced 3D printing filament.

9. The method for forming continuous fiber-reinforced 3D printing filaments as described in claim 8, characterized in that, The material is a mixture of continuous fibers and resin, or the material is a preform of a continuous fiber reinforced resin matrix composite material.

10. The method for forming continuous fiber-reinforced 3D printing filaments as described in claim 9, characterized in that, The parameters include: porosity not exceeding 3%, and continuous fiber volume content of 20-75%.

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