Pultrusion method for continuous fiber reinforced thermoplastic composite material

Abstract

The invention discloses a continuous fiber reinforced thermoplastic composite pultrusion method. The preparation method comprises the following steps: modifying different thermoplastic resins, firstly preparing a continuous fiber reinforced thermoplastic pre-impregnated wire material and a pre-impregnated strip material through a melt impregnation process, then feeding the pre-impregnated wire material and the pre-impregnated strip material into a second impregnation mold after passing through heat preservation equipment, and carrying out secondary impregnation, exhausting and cooling molding. According to the method, the influences of difficulty in dipping, higher porosity and unstable quality in large-section pultrusion production are greatly improved, and the production efficiency and the mechanical property of the pultrusion profile are improved.

Description

Technical Field

[0001] The present invention belongs to the field of thermoplastic composite profiles manufacturing, and particularly relates to a pultrusion forming method for continuously fiber-reinforced thermoplastic composites Background Art

[0002] Continuously fiber-reinforced thermoplastic composites have the advantages of light weight, high strength, corrosion resistance, etc. Pultruded profiles can be produced continuously, achieving lightweight and cost reduction. Currently, the main method for preparing large-section thermoplastic composite profiles is one-step forming, which directly pulls the fiber reinforcement into the impregnation mold, impregnates, and cools and forms. This method has simple steps, but in the process of forming large-section profiles, not only is it difficult to arrange the fiber bundles, especially for thermoplastic resins with high viscosity, the multi-fiber and high-viscosity result in poor impregnation effect of pultruded products, high void defects, unstable product quality, and the required impregnation mold is large and the equipment is heavy, making it inconvenient for installation

[0003] Chinese Patent Application CN202410384579.X discloses an impregnation device and process for continuously fiber-reinforced thermoplastic polymer composites, which uses a wavy flow channel instead of a traditional impregnation tank and adjusts the flow channel gap by moving the lower cover of the mold. However, its impregnation mold has a complex structure and cannot form profiles with large cross-sectional dimensions. Chinese Patent Application CN201910602617.3 discloses a preparation method and product of a woven continuous fiber thermoplastic prepreg tape. This invention uses a two-step impregnation method. In the first impregnation, only a layer of resin is simply coated, and the yarn spreading roller does not fully spread the yarn, so a relatively sufficient impregnation is not achieved. Only one impregnation mold is used in the first impregnation, and the entire impregnation and forming process is only applicable to the impregnation of fiber tapes with relatively small and simple cross-sectional shapes and is not applicable to pultruded profiles. Chinese Patent Application CN202310767676.2 discloses a continuous carbon fiber prepreg manufacturing technology, which uses a motor-driven sizing roller to coat the fiber bundle with resin. The yarn spreading mechanism in the patent cannot adaptively change the movement form of the yarn spreading roller according to the change in the pulling force to adjust the pultrusion force and protect the fiber. Chinese Patent Application CN202311266861.X discloses a pre-impregnation method and system for impregnating fibers using vacuum. A vacuum container is used to form a seal with the laid fibers, so that the resin matrix on the upper surface of the prepreg penetrates the fiber bundle and flows downward to achieve continuous impregnation of the fibers. This impregnation method has a large cavity. Although the structure is simple, it is not built into the impregnation mold, the seal is not tight, and only vacuum is relied on to drive resin impregnation, resulting in poor impregnation effect Summary of the Invention

[0004] Based on the above technical problems, the present invention provides a pultrusion molding method for continuous fiber reinforced thermoplastic composites, which can effectively overcome the production disadvantages of difficult impregnation, high porosity, poor product performance stability, and difficult arrangement of fiber reinforcements in the production of large cross-section pultruded products, effectively improve production efficiency, and reduce costs. The specific solution of the present invention is as follows:

[0005] A pultrusion molding method for continuous fiber reinforced thermoplastic composites, comprising the following steps:

[0006] 1) Thermoplastic resin, antioxidant, flow modifier, and compatibilizer are respectively added in proportion to the twin-screw extruder of the fiber bundle pre-impregnation mold, the twin-screw extruder of the fiber cloth pre-impregnation mold, and the twin-screw extruder of the second impregnation pultrusion mold for mixing and plasticizing, and then are respectively transported to the fiber bundle pre-impregnation mold, the fiber cloth pre-impregnation mold, and the second impregnation pultrusion mold. The continuous fiber bundle and the continuous fiber cloth are pulled out from the fiber rack by the traction machine, and under the control of the tension regulating device, are respectively transported to the fiber bundle pre-impregnation mold and the fiber cloth pre-impregnation mold for pre-impregnation;

[0007] 2) The pre-impregnated continuous fiber bundle and continuous fiber cloth are transported to the impregnation pultrusion mold through the heat preservation device and are pultruded into fiber reinforced composites by the front preforming plate, middle preforming plate, and rear preforming plate in the impregnation pultrusion mold. A low-pressure exhaust chamber is provided between the rear preforming plate in the impregnation pultrusion mold and the outlet of the second impregnation pultrusion mold, which can effectively exhaust the gas involved in the pultrusion process. At the same time, the second impregnation pultrusion mold is replenished with materials in real time through the twin-screw extruder;

[0008] 3) The fiber reinforced thermoplastic composite material formed by secondary impregnation and pultrusion is transported to the cooling mold for cooling and shaping, and after being cut by a cutting saw, the pultruded product with the required length is obtained.

[0009] Among them, the fiber bundle pre-impregnation mold and the fiber cloth pre-impregnation mold have a mold body. The yarn spreading roller is arranged in the mold body. Tapered grooves are opened at both ends of the yarn spreading roller. Bolt through holes are opened on the side plates on both sides of the mold body. The yarn spreading roller is fixed on the side plates of the mold body by using headless hexagon socket screws. When the headless hexagon socket screws on both sides are screwed into the mold body, the tapered heads of the screws coincide with the tapered grooves at both ends of the yarn spreading roller, applying a positive pressure to the yarn spreading roller to position the yarn spreading roller at the designated position.

[0010] Among them, the tension adjusting device includes a tension detection and control system, a three-roll tension detection device, a screw drive servo motor, a socket head cap screw, and a yarn spreading roller. The three-roll tension detection device transmits the detected tension data to the tension detection and control system. Through the PID control of the tension detection and control system, a control signal is output to the screw drive servo motor. The screw drive servo motor is rigidly connected to the socket head cap screw through a hexagonal rod. The adjustment of the screwing-in amount of the socket head cap screw is realized through the screw drive servo motor, the positive pressure applied to the yarn spreading roller is controlled, and thus the friction force between the tapered head of the socket head cap screw and the tapered groove is controlled. When the three-roll tension detection device detects a large tension, the tension detection and control system controls the motor to rotate to reduce the screwing-in amount, the friction force decreases, and the yarn spreading roller is in a moving state. When the three-roll tension detection device detects a small tension, the tension detection and control system controls the motor to rotate to increase the screwing-in amount, the friction force increases, and the yarn spreading roller is in a fixed static state.

[0011] Among them, the second impregnation pultrusion die includes a front preforming plate, a middle preforming plate, and a rear preforming plate. Grooves are formed on the side wall of the second impregnation pultrusion die for fixing each preforming plate. Sealing grooves are formed at the top and bottom of the second impregnation pultrusion die at the fixed position of the rear preforming plate for the sealed connection between the rear preforming plate and the side wall of the second impregnation pultrusion die. A low-pressure exhaust chamber is provided between the rear preforming plate and the outlet of the second impregnation pultrusion die. An exhaust hole is provided at the top of the low-pressure exhaust chamber, and the exhaust hole is connected to a vacuum pump through an external pipeline to evacuate and decompress the gas inside the fiber-reinforced composite material.

[0012] Among them, the heat preservation device is an infrared heat preservation device, and the heat preservation temperature is 5 - 10 °C higher than the melting temperature of the thermoplastic resin.

[0013] Among them, the thermoplastic resin is selected from nylon 6, polypropylene, polylactic acid, polyether ether ketone, etc.

[0014] Among them, the mass ratio of the thermoplastic resin, antioxidant, flow modifier, and compatibilizer is 100:1 - 2:3 - 5:4 - 10.

[0015] Among them, the continuous fiber bundle and the continuous fiber cloth are one or more of glass fiber, carbon fiber, and basalt fiber.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0017] 1. Through step-by-step impregnation, the impregnation difficulty of large-section pultruded profiles is greatly reduced, the arrangement difficulty of the fiber reinforcement in large-section pultruded profiles is reduced, the porosity content in the pultruded profiles is reduced, and the impregnation quality of the pultruded products is significantly improved;

[0018] 2. By introducing a low-pressure exhaust chamber into the impregnation pultrusion die, degassing of voids in the product is achieved, effectively reducing the porosity when thermoplastic resin impregnates the fibers and improving the stability of the product performance.

[0019] 3. A tension detection and control system is set up. By controlling the change in the movement form of the yarn spreading roller, dynamic adjustment of the fiber tension in pultrusion production is realized, thereby reducing the frictional damage of the fiber bundle and improving the mechanical properties of the pultruded product.

[0020] 4. By modifying the thermoplastic resin, the anti-aging property and toughness of the pultruded profile are increased, meeting the requirements of more engineering applications. Description of the Drawings

[0021] Figure 1 It is a schematic flow chart of the pultrusion molding method for continuous fiber reinforced thermoplastic composites of the present invention;

[0022] Figure 2 It is a cross-sectional view of the yarn spreading roller structure in the fiber strand impregnation die and the fiber cloth impregnation die in the pultrusion molding method for continuous fiber reinforced thermoplastic composites of the present invention;

[0023] Figure 3 It is a cross-sectional view of the structure of the second impregnation pultrusion die in the pultrusion molding method for continuous fiber reinforced thermoplastic composites of the present invention;

[0024] Figure 4 It is a schematic diagram of the continuous fiber reinforced composite pultruded product prepared by the pultrusion molding method for continuous fiber reinforced thermoplastic composites of the present invention.

[0025] In the figure: 1. Twin-screw extruder of the fiber strand pre-impregnation die; 2. Fiber strand pre-impregnation die; 3. Twin-screw extruder of the fiber cloth pre-impregnation die; 4. Fiber cloth pre-impregnation die; 5. Die body; 6. Fiber rack; 7. Yarn spreading roller; 8. Tension detection and control system; 9. Screw drive servo motor; 10. Three-roller tension detection device; 11. Heat preservation device; 12. Socket head cap screw; 13. Twin-screw extruder of the second impregnation pultrusion die; 14. Second impregnation pultrusion die; 15. Front preforming plate; 16. Middle preforming plate; 17. Rear preforming plate; 18. Low-pressure exhaust chamber; 19. Vacuum pump; 20. Cooling die; 21. Track traction machine; 22. Cutting saw; 23. Pultruded product. Detailed Embodiments

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0027] Figure 1The pultrusion method of the continuous fiber reinforced thermoplastic composite material of the present invention is shown. The thermoplastic resin, antioxidant, flow modifier and compatibilizer are respectively added into the twin-screw extruder 1 of the fiber bundle pre-impregnation die, the twin-screw extruder 3 of the fiber cloth pre-impregnation die and the twin-screw extruder 13 of the second impregnation pultrusion die for mixing and plasticizing, and then are respectively conveyed to the fiber bundle pre-impregnation die 2, the fiber cloth pre-impregnation die 4 and the second impregnation pultrusion die 14. The continuous fiber bundle and the continuous fiber cloth are drawn out from the fiber rack 6 under the pulling of the tractor 20, and are respectively conveyed to the fiber bundle pre-impregnation die 2 and the fiber cloth pre-impregnation die 4 for pre-impregnation under the regulation of the tension regulating device.

[0028] The fiber bundle pre-impregnation die 2 and the fiber cloth pre-impregnation die 4 respectively include a die body 5 and a plurality of yarn spreading rollers 7. The yarn spreading rollers 7 are arranged in parallel in the die body 5 and are perpendicular to the feeding direction of the fiber bundle. The die body 5 is provided with threaded through holes for positioning the yarn spreading rollers 7.

[0029] As Figure 2 shown, tapered grooves are formed at both ends of the yarn spreading roller 7, and bolt through holes are formed on the side plates on both sides of the die body 5. The yarn spreading roller 7 is fixed on the side plate of the die body 5 by using a socket head cap screw 12 without a head. When the socket head cap screws 12 on both sides are screwed into the die body 5, the tapered heads of the screws coincide with the tapered grooves at both ends of the yarn spreading roller 7, and a positive pressure is applied to the yarn spreading roller 7 to position the yarn spreading roller 7 at a specified position.

[0030] The tension regulating device includes a tension detection and control system 8, a three-roller tension detection device 10, a screw driving servo motor 9, a socket head cap screw 12 without a head and a yarn spreading roller 7. The three-roller tension detection device 10 transmits the detected tension data to the tension detection and control system 8. Through the PID control of the tension detection and control system 8, a control signal is output to the screw driving servo motor 9. The screw driving servo motor 9 is rigidly connected to the socket head cap screw 12 without a head through a hexagonal rod. The adjustment of the screwing-in amount of the socket head cap screw 12 is realized through the screw driving servo motor 9, the positive pressure applied to the yarn spreading roller 7 is controlled, and further the friction force between the tapered head of the socket head cap screw without a head and the tapered groove is controlled. When the three-roller tension detection device 10 detects that the tension is large, the tension detection and control system 8 controls the motor to rotate to reduce the screwing-in amount, the friction force is reduced, and the yarn spreading roller 7 is in a moving state. When the three-roller tension detection device 10 detects that the tension is small, the tension detection and control system 8 controls the motor to rotate to increase the screwing-in amount, the friction force is increased, and the yarn spreading roller 7 is in a fixed and static state.

[0031] The pre-impregnated continuous fiber bundles and continuous fiber cloth are transported to the impregnation pultrusion die 14 through the heat preservation device 11 for heat preservation, and are pultruded into fiber-reinforced composites through the front preforming plate 15, middle preforming plate 16 and rear preforming plate 17 in the impregnation pultrusion die 14. A low-pressure exhaust chamber 18 is provided between the rear preforming plate 17 in the impregnation pultrusion die 14 and the outlet of the second impregnation pultrusion die 14, which can effectively remove the gas involved in the pultrusion process. At the same time, the second impregnation pultrusion die 14 is replenished with materials in real time through the second impregnation pultrusion die twin-screw extruder 13. Preferably, the heat preservation device 11 is an infrared heat preservation device, and the heat preservation temperature is 5-10 °C higher than the melting temperature of the thermoplastic resin.

[0032] As Figure 3 shown, the second impregnation pultrusion die 14 includes a front preforming plate 15, a middle preforming plate 16 and a rear preforming plate 17. The side wall of the second impregnation pultrusion die 14 is provided with grooves for fixing each preforming plate. The top and bottom of the second impregnation pultrusion die 14 at the fixed position of the rear preforming plate 17 are provided with sealing grooves for the sealed connection between the rear preforming plate 17 and the side wall of the second impregnation pultrusion die 14. A low-pressure exhaust chamber 18 is provided between the rear preforming plate 17 and the outlet of the second impregnation pultrusion die 14. The top of the low-pressure exhaust chamber 18 is provided with an exhaust hole, and the exhaust hole is connected to a vacuum pump 19 through an external pipeline to evacuate and decompress the gas in the fiber-reinforced composite material.

[0033] The fiber-reinforced thermoplastic composite material formed by secondary impregnation and pultrusion is transported to the cooling die 20 for cooling and shaping, and is cut by a cutting saw 22 to obtain a pultruded product 23 of the required length (as Figure 4 shown).

[0034] Preferably, the thermoplastic resin is selected from nylon 6, polypropylene, polylactic acid, polyether ether ketone, etc. The mass ratio of the thermoplastic resin, antioxidant, flow modifier and compatibilizer is 100:1-2:3-5:4-10. The continuous fiber bundles and continuous fiber cloth are one or several of glass fiber, carbon fiber and basalt fiber. Specific Example 1

[0036] 1 part by weight of antioxidant, 3 parts by weight of modified flow agent, 10 parts by weight of compatibilizer and 100 parts by weight of nylon 6 resin are mixed evenly and added to the fiber bundle pre-impregnation die twin-screw extruder 1, fiber cloth pre-impregnation die twin-screw extruder 3 and second impregnation pultrusion die twin-screw extruder 13, and are respectively extruded into the fiber bundle pre-impregnation die 2, fiber cloth pre-impregnation die 4 and second impregnation pultrusion die 14 through plasticization by the twin-screw extruder, and the die temperature is set at 235 °C.

[0037] Meanwhile, continuously draw out the continuous fiber bundle and the continuous fiber cloth from the fiber rack 6, respectively pass them through the tension detection and control system 8, and introduce them into the fiber bundle pre-impregnation die 2 and the fiber cloth pre-impregnation die 4. The fiber bundle and the fiber cloth pass through the yarn spreading roller 7 in the die to realize the fiber dispersion and spreading of the fiber bundle and the fiber cloth. The molten thermoplastic resin is pressed into the interior of the continuous fiber bundle and the continuous fiber cloth through the extrusion pressure between the continuous fiber bundle and the continuous fiber cloth and the yarn spreading roller 7 to achieve impregnation. The pre-impregnated fiber bundle and the pre-impregnated fiber cloth enter the second impregnation pultrusion die 14 through the heat preservation device 11 at the same time, and pass through the front preforming plate 15, the middle preforming plate 16 and the rear preforming plate 17 to realize the hierarchical and zonal arrangement of the fiber reinforcement, and gradually form the profile cross-sectional shape. When the preformed profile passes through the low-pressure exhaust chamber 18, the internal air holes overflow to the surface of the product in the low-pressure environment, reducing the porosity of the product. Then it enters the cooling die 20, the cooling temperature is set at 220°C, the resin is cooled and crystallized and shaped, and it leaves the die under the traction of the caterpillar tractor 21, and is cut to a fixed length by the cutting saw 22 to obtain the final pultruded product 23.

[0038] After testing, the tensile strength, flexural strength, interlaminar shear strength and porosity of the prepared pultruded composite material can reach 1082 MPa, 958 MPa, 70.6 MPa and 0.95% respectively. Specific Example 2

[0040] Mix 1 part by weight of antioxidant, 3 parts by weight of modified flow agent, 12 parts by weight of compatibilizer and 100 parts by weight of polylactic acid resin evenly, and then add them to the twin-screw extruder 1 of the fiber bundle pre-impregnation die, the twin-screw extruder 3 of the fiber cloth pre-impregnation die and the twin-screw extruder 13 of the second impregnation pultrusion die. After being plasticized by the twin-screw extruder, they are respectively extruded into the fiber bundle pre-impregnation die 2, the fiber cloth pre-impregnation die 4 and the second impregnation pultrusion die 14, and the die temperature is set at 250°C.

[0041] Meanwhile, the continuous fiber bundles and the continuous fiber cloth are drawn out from the fiber rack 6, respectively pass through the tension detection and control system 8, and are introduced into the fiber bundle pre-impregnation die 2 and the fiber cloth pre-impregnation die 4. The fiber bundles and the fiber cloth pass through the yarn spreading rollers 7 in the die to realize the fiber dispersion and spreading of the fiber bundles and the fiber cloth. The molten thermoplastic resin is pressed into the interiors of the continuous fiber bundles and the continuous fiber cloth through the extrusion pressure between the continuous fiber bundles and the continuous fiber cloth and the yarn spreading rollers 7 to achieve impregnation. The pre-impregnated fiber bundles and the pre-impregnated fiber cloth enter the second impregnation pultrusion die 14 through the heat preservation device 11 at the same time, and pass through the front preforming plate 15, the middle preforming plate 16 and the rear preforming plate 17 to realize the hierarchical and zonal arrangement of the fiber reinforcement, and gradually form the profile cross-sectional shape. When the preformed profile passes through the low-pressure exhaust chamber 18, the internal air holes overflow to the surface of the product in the low-pressure environment, reducing the porosity of the product. Then it enters the cooling die 20, the cooling temperature is set at 240 °C, the resin is cooled and crystallized and shaped, and leaves the die under the traction of the caterpillar tractor 21, and is cut to a fixed length by the cutting saw 22 to obtain the final pultruded product 23.

[0042] After testing, the tensile strength, flexural strength, interlaminar shear strength and porosity of the prepared pultruded composite material can reach 895 MPa, 256 MPa, 30.4 MPa and 0.89% respectively. Specific Example 3

[0044] 1 part by weight of antioxidant, 3 parts by weight of modified flow agent, 10 parts by weight of compatibilizer and 100 parts by weight of polyetheretherketone resin are mixed evenly and then added to the twin-screw extruder 1 of the fiber bundle pre-impregnation die, the twin-screw extruder 3 of the fiber cloth pre-impregnation die and the twin-screw extruder 13 of the second impregnation pultrusion die, and are respectively extruded into the fiber bundle pre-impregnation die 2, the fiber cloth pre-impregnation die 4 and the second impregnation pultrusion die 14 through plasticization by the twin-screw extruder, and the die temperature is set at 390 °C.

[0045] Meanwhile, the continuous fiber bundle and the continuous fiber cloth are drawn out from the fiber rack 6, respectively pass through the tension detection and control system 8, and are introduced into the fiber bundle pre-impregnation die 2 and the fiber cloth pre-impregnation die 4. The fiber bundle and the fiber cloth pass through the yarn spreading roller 7 in the die to realize the fiber dispersion and spreading of the fiber bundle and the fiber cloth. The molten thermoplastic resin is pressed into the interior of the continuous fiber bundle and the continuous fiber cloth through the extrusion pressure between the continuous fiber bundle and the continuous fiber cloth and the yarn spreading roller 7 to achieve impregnation. The pre-impregnated fiber bundle and the pre-impregnated fiber cloth enter the second impregnation pultrusion die 14 through the heat preservation device 11 at the same time, and pass through the front preforming plate 15, the middle preforming plate 16 and the rear preforming plate 17 to realize the hierarchical and zonal arrangement of the fiber reinforcement, and gradually form the profile cross-sectional shape. When the preformed profile passes through the low-pressure exhaust chamber 18, the internal pores overflow to the surface of the product in the low-pressure environment, reducing the porosity of the product. Subsequently, it enters the cooling die 20, the cooling temperature is set at 340 °C, and the resin is cooled and crystallized and shaped. It leaves the die under the traction of the caterpillar tractor 21 and is cut to a fixed length by the cutting saw 22 to obtain the final pultruded product 23.

[0046] After testing, the tensile strength, flexural strength, interlaminar shear strength and porosity of the prepared pultruded composite material can reach 1682 MPa, 1023 MPa, 71.6 MPa and 1.1% respectively.

[0047] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. A pultrusion method for continuously fiber-reinforced thermoplastic composites, characterized in that, The steps include the following: 1) Thermoplastic resin, antioxidant, flow modifier and compatibilizer are respectively added in proportion into the twin-screw extruder (1) of the fiber bundle pre-impregnation die, the twin-screw extruder (3) of the fiber cloth pre-impregnation die and the twin-screw extruder (13) of the second impregnation pultrusion die for mixing and plasticizing, and then are respectively conveyed to the fiber bundle pre-impregnation die (2), the fiber cloth pre-impregnation die (4) and the second impregnation pultrusion die (14). The continuous fiber bundle and the continuous fiber cloth are led out from the fiber rack (6) under the pulling of the tractor (20), and are respectively conveyed to the fiber bundle pre-impregnation die (2) and the fiber cloth pre-impregnation die (4) for pre-impregnation under the regulation of the tension regulating device; 2) The pre-impregnated continuous fiber bundle and continuous fiber cloth are conveyed to the impregnation pultrusion die (14) through the heat preservation device (11) for heat preservation, and are pultruded into fiber reinforced composite materials through the front preforming plate (15), the middle preforming plate (16) and the rear preforming plate (17) in the impregnation pultrusion die (14). A low-pressure exhaust chamber (18) is arranged between the rear preforming plate (17) in the impregnation pultrusion die (14) and the outlet of the second impregnation pultrusion die (14), which can effectively discharge the gas involved in the pultrusion process. At the same time, the second impregnation pultrusion die (14) is replenished with materials in real time through the second impregnation pultrusion die twin-screw extruder (13); 3) The fiber reinforced thermoplastic composite material formed by secondary impregnation and pultrusion is conveyed to the cooling die (20) for cooling and shaping, and is cut by the cutting saw (22) to obtain the pultruded product (23) with the required length.

2. The pultrusion forming method of a continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, The fiber bundle pre-impregnation die (2) and the fiber cloth pre-impregnation die (4) have a die body (5). The yarn spreading roller (7) is arranged in the die body (5). Tapered grooves are opened at both ends of the yarn spreading roller (7). Bolt through holes are opened on the side plates on both sides of the die body (5). The yarn spreading roller (7) is fixed on the side plates of the die body (5) by using headless socket head cap screws (12). When the headless socket head cap screws (12) on both sides are screwed into the die body (5), the tapered heads of the screws coincide with the tapered grooves at both ends of the yarn spreading roller (7) and contact each other, applying a positive pressure to the yarn spreading roller (7) to position the yarn spreading roller (7) at a specified position.

3. A pultrusion method for continuously fiber-reinforced thermoplastic composites according to claim 1 or 2, characterized in that The described tension adjustment device includes a tension detection and control system (8), a three-roll tension detection device (10), a screw drive servo motor (9), a socket head cap screw (12), and a yarn spreading roller (7). The three-roll tension detection device (10) transmits the detected tension data to the tension detection and control system (8). Through the PID control of the tension detection and control system (8), a control signal is output to the screw drive servo motor (9). The screw drive servo motor (9) is rigidly connected to the socket head cap screw (12) through a hexagonal rod. The adjustment of the screwing-in amount of the socket head cap screw (12) is achieved through the screw drive servo motor (9) to control the positive pressure applied to the yarn spreading roller (7), and further control the friction force between the socket head of the socket head cap screw and the tapered groove. When the three-roll tension detection device (10) detects a large tension, the tension detection and control system (8) controls the motor to rotate to reduce the screwing-in amount, the friction force decreases, and the yarn spreading roller (7) is in a moving state. When the three-roll tension detection device (10) detects a small tension, the tension detection and control system (8) controls the motor to rotate to increase the screwing-in amount, the friction force increases, and the yarn spreading roller (7) is in a fixed and stationary state.

4. A pultrusion method for a continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that, The described second impregnation pultrusion die (14) includes a front preforming plate (15), a middle preforming plate (16), and a rear preforming plate (17). Grooves are provided on the side wall of the second impregnation pultrusion die (14) for fixing each preforming plate. Sealing grooves are provided at the top and bottom of the second impregnation pultrusion die (14) at the fixed position of the rear preforming plate (17) for the sealed connection between the rear preforming plate (17) and the side wall of the second impregnation pultrusion die (14). A low-pressure exhaust chamber (18) is provided between the rear preforming plate (17) and the outlet of the second impregnation pultrusion die (14). An exhaust hole is provided at the top of the low-pressure exhaust chamber (18), and the exhaust hole is connected to a vacuum pump (19) through an external pipeline to evacuate and decompress the gas inside the fiber-reinforced composite material.

5. A pultrusion method for a continuous fiber reinforced thermoplastic composite material according to claim 1, wherein The described heat preservation device (11) is an infrared heat preservation device, and the heat preservation temperature is 5 - 10 °C higher than the melting temperature of the thermoplastic resin.

6. A pultrusion method for a continuous fiber reinforced thermoplastic composite material according to any one of claims 1-5, characterized in that The described thermoplastic resin is selected from nylon 6, polypropylene, polylactic acid, polyether ether ketone, etc.

7. A pultrusion method for a continuous fiber reinforced thermoplastic composite material according to any one of claims 1-5, characterized in that, The mass ratio of the described thermoplastic resin, antioxidant, flow modifier, and compatibilizer is 100:1 - 2:3 - 5:4 - 10.

8. A pultrusion method for a continuous fiber reinforced thermoplastic composite material according to claims 1-5, characterized in that, The described continuous fiber bundle and continuous fiber cloth are one or several of glass fiber, carbon fiber, and basalt fiber.

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