Melt impregnation device and method for continuous fiber reinforced thermoplastic composite material

Abstract

The invention relates to a melt impregnation device and method for a continuous fiber reinforced thermoplastic composite material, and belongs to the technical field of composite material forming. A lower die dipping tank in the device is provided with a fiber inlet and a prepreg outlet, a plurality of variable-diameter dipping rollers are arranged between the fiber inlet and the prepreg outlet, the two ends of each variable-diameter dipping roller are a large-diameter end and a small-diameter end respectively, the large-diameter ends and the small-diameter ends are connected through smooth roller surfaces, and the small-diameter ends of the adjacent variable-diameter dipping rollers face opposite directions; the mold cover plate covers the lower mold dipping tank, the upper mold cover plate is provided with a plurality of downward supporting blocks, the supporting blocks are located between the adjacent variable-diameter dipping rollers, and the lowest points of the supporting blocks are lower than the highest points of the small-diameter ends of the variable-diameter dipping rollers. Through the variable-diameter design of the variable-diameter dipping roller, the supporting blocks and the fiber guide columns are matched, the unfolding effect of fibers is maintained and improved, the problems of fiber breakage, gathering and twisting are effectively solved, and high-quality output of prepreg is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of melt impregnation molds and processes and the technical field of composite material molding, and specifically relates to a melt impregnation device and method for continuous fiber reinforced thermoplastic composite materials. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Continuous fiber reinforced thermoplastic composites have shown broad application prospects in aerospace, national defense, rail transportation, and new energy vehicles due to their excellent performance advantages, such as high damage tolerance, excellent impact resistance, high fracture toughness, recyclability, and short molding and manufacturing cycle. However, thermoplastic resins usually have high melting points and melt viscosities, which pose severe challenges to the melt impregnation process of continuous fiber reinforced thermoplastic composite prepregs. In the prior art, the melt impregnation process of prepregs often leads to problems such as poor fiber dispersion, insufficient resin impregnation, and fiber breakage, which seriously affects the impregnation quality of the prepregs and the stability of the mechanical properties.

[0004] At present, the melt impregnation process of continuous fiber reinforced thermoplastic composites generally adopts a melt impregnation device equipped with a curved / wavy impregnation flow channel or a multi-channel columnar impregnation roller. The impregnation effect is improved by designing the flow channel length and structure, the number of impregnation rollers and the transmission principle.

[0005] Chinese patent CN118269384A discloses a combined melt impregnation mold system, which forms a wavy resin flow channel through fixed upper and lower templates, so that the continuous fiber bundle can be melt impregnated through the resin flow channel; Chinese patent CN103802231A proposes a double-sided melt impregnation device with a trapezoidal cross-section curved flow channel, which impregnates the fiber through a double-sided resin distribution flow channel structure. However, the impregnation technology based on the flow channel structure has significant limitations: the tension and support force of the fiber during the impregnation process are low, which easily leads to high resin content, and problems such as fiber aggregation, bending or dry fibers in the prepreg.

[0006] Chinese patents CN111452254A and CN118617630A disclose an impregnation mold that forms a W-shaped channel by fixing an impregnation roller. However, due to the large and difficult-to-control fiber tension, this solution easily causes problems such as decreased fiber dispersion quality and fiber breakage and bending. Chinese patent CN114801254A proposes a melt impregnation mold comprising a rotating impregnation roller and a pressure-adjusting impregnation roller, which improves the impregnation quality by adjusting the fiber tension. However, for thermoplastic resins with high melting temperatures and high melt viscosity (such as polyetheretherketone, polyphenylene sulfide, polyetherimide and polyetherketoneketone, etc.), this cylindrical impregnation roller still causes obvious fiber breakage, twisting, aggregation and other problems, affecting the impregnation quality and the thickness consistency of the prepreg. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a melt impregnation device and method for continuous fiber reinforced thermoplastic composite materials, which utilizes variable diameter impregnation rollers and related devices to achieve further expansion of fibers during the melt impregnation process, effectively reduce fiber breakage, hanging and entanglement, and have a broken wire self-cleaning function, thereby significantly improving the impregnation quality and production efficiency of fiber reinforced thermoplastic composite prepregs.

[0008] In order to achieve the above object, the technical solution of the present invention is: In a first aspect, a melt impregnation device for a continuous fiber reinforced thermoplastic composite material comprises an upper mold cover plate and a lower mold impregnation tank; The lower mold impregnation tank is provided with a fiber inlet and a prepreg outlet, and a plurality of variable diameter impregnation rollers are provided between the fiber inlet and the prepreg outlet, wherein the axial direction of the variable diameter impregnation roller is horizontal and perpendicular to the axial direction of the fiber, and the two ends of the variable diameter impregnation roller are respectively a large diameter end and a small diameter end, the large diameter end and the small diameter end are connected by a smooth roller surface, and the small diameter ends of adjacent variable diameter impregnation rollers face oppositely; The upper mold cover plate covers the lower mold dipping tank, and the upper mold cover plate is provided with a plurality of downward support blocks, the support blocks are located between adjacent variable diameter dipping rollers, and the lowest point of the support blocks is lower than the highest point of the small diameter end of the variable diameter dipping roller.

[0009] In a second aspect, a melt impregnation method of a continuous fiber reinforced thermoplastic composite material based on the above device comprises the following steps: S1. Adjust the support block and the variable diameter impregnation roller to the set height; S2, the continuous fiber bundle is introduced into the impregnation tank through the fiber inlet, and after being guided and unfolded by the fiber guide column, the support block and the variable diameter impregnation roller, it passes through the impregnation tank through the prepreg outlet; S3, closing the upper mold cover plate and the lower mold dipping tank, raising the temperature and injecting the high-temperature resin melt into the lower mold dipping tank to a set liquid level; S4. The continuous fibers are pulled through a pulling device to complete the impregnation.

[0010] The beneficial effects of the present invention are: The device and process of the present invention, through the variable diameter design of the variable diameter impregnation roller, cooperates with the support block and the fiber guide column, sets the fiber transmission path to a three-dimensional tortuous state, maintains and improves the fiber expansion effect, effectively solves the fiber breakage, aggregation and twisting problems, and ensures the high-quality output of the prepreg; on the other hand, the broken fibers are gathered to the small diameter end of the variable diameter impregnation roller, that is, flow and accumulate to both sides of the impregnation tank, realize the self-cleaning function of the core working area in the middle of the impregnation tank, and have good production stability and operability. By introducing ultrasonic vibration, a large number of bubbles in the melt are eliminated, and the resin impregnation effect is further improved. Through the design of the post-processing mechanism, the resin content, thickness uniformity and surface smoothness of the prepreg after impregnation are further accurately controlled and regulated, thereby improving the final quality of the prepreg. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0012] Figure 1 This is a schematic structural diagram of the melt impregnation device of the continuous fiber reinforced thermoplastic composite material in Example 1.

[0013] Figure 2 This is a schematic diagram of the structure of the variable diameter impregnation roller in Example 1.

[0014] Figure 3 This is a guide path diagram of the continuous fiber in Example 1.

[0015] Figure 4 Schematic diagram of the outline of the support block in Example 1.

[0016] Figure 5 This is a schematic diagram of the installation of the support block in Example 1.

[0017] Figure 6 Schematic diagram of the structure of the post-processing mechanism in Example 1.

[0018] Figure 7 This is a schematic diagram of the structure of the variable diameter impregnation roller in Example 2.

[0019] Figure 8 Schematic diagram of the outline of the support block in Example 2.

[0020] Fig. 9 This is a schematic diagram of the installation of the support block in Example 2.

[0021] Fig.10This is a guide path diagram of the continuous fiber in Example 2.

[0022] Among them, 1. upper mold cover plate; 2. lower mold impregnation tank; 3. variable diameter impregnation roller; 4. support block; 5. fiber guide column; 6. extruder pouring port; 71. first liquid level sensor; 72. second liquid level sensor; 8. ultrasonic vibration mechanism; 9. heating tube; 10. exhaust port; 11. fiber inlet; 12. prepreg outlet; 13. continuous fiber; 14. rotatable horizontal axis; 15. upper cover plate; 16. lower chamber; 17. extrusion roller; 18. radiation heater. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] A melt impregnation device for continuous fiber reinforced thermoplastic composite material, comprising an upper mold cover plate and a lower mold impregnation tank; The lower mold impregnation tank is provided with a fiber inlet and a prepreg outlet, and a plurality of variable diameter impregnation rollers are provided between the fiber inlet and the prepreg outlet, wherein the axial direction of the variable diameter impregnation roller is horizontal and perpendicular to the axial direction of the fiber, and the two ends of the variable diameter impregnation roller are respectively a large diameter end and a small diameter end, the large diameter end and the small diameter end are connected by a smooth roller surface, and the small diameter ends of adjacent variable diameter impregnation rollers face oppositely; The upper mold cover plate covers the lower mold dipping tank, and the upper mold cover plate is provided with a plurality of downward support blocks, the support blocks are located between adjacent variable diameter dipping rollers, and the lowest point of the support blocks is lower than the highest point of the small diameter end of the variable diameter dipping roller.

[0026] In the above setting, the support block can effectively adjust the tension of the continuous fiber, and the variable diameter impregnation roller can further unfold the fiber yarn, thereby improving its impregnation effect and uniformity. When broken fibers appear, the broken fibers can be collected to the small diameter end of the variable diameter impregnation roller to achieve a self-cleaning function, thereby eliminating broken fibers in the prepreg product and preventing the impregnation device from being blocked.

[0027] Optionally, the roller surface of the variable diameter impregnation roller is a straight conical surface or a convex conical surface. This configuration of the impregnation roller can improve the yarn spreading effect and realize the self-cleaning function of broken yarns. Compared with the cylindrical impregnation roller, at the same impregnation tank length, the fiber tension is effectively reduced, thereby improving the impregnation effect and efficiency.

[0028] Optionally, the support block profile is the same as the roller surface profile of the variable diameter impregnation roller, so that the gap between the support block surface and the roller surface forms a channel of equal width, prompting the passing fiber bundle to unfold along the roller surface and preventing twisting from passing through, and the gap size is between 0.1-0.7mm.

[0029] Optionally, the upper mold cover plate is provided with an extruder pouring port for replenishing the melt into the lower mold immersion tank; the upper mold cover plate is provided with an exhaust port for exhausting gas in the mold cavity.

[0030] Optionally, the upper mold cover plate is provided with a liquid level sensor. When the liquid level of the resin melt in the lower mold impregnation tank is lower than the minimum set value, the low-level sensor sends a signal to the extruder connected to the mold to control the extruder to inject the resin melt into the impregnation tank; when the liquid level reaches the high-level set value, the high-level sensor controls the extruder to stop injecting the resin melt.

[0031] Optionally, the upper mold cover plate is provided with a heating tube, which is evenly embedded in the upper mold cover plate and whose switching state is controlled by a temperature sensor in the lower mold dipping tank to maintain a stable temperature of the resin melt.

[0032] Optionally, a fiber guide column is provided in the lower mold impregnation tank, the height of the fiber guide column is higher than the roller surface of the variable diameter impregnation roller, and the variable diameter impregnation roller is located between the fiber guide column and the support block; the fiber guide column is designed to be non-rotating and rotatable adjustable modes, and the tension during the fiber impregnation process can be increased in the non-rotating mode.

[0033] Optionally, a heating tube is provided in the lower mold impregnation tank, and the heating tube is dispersedly arranged on the entire tank wall, so as to uniformly heat the resin melt and maintain a constant temperature; an ultrasonic vibration mechanism is provided in the lower mold impregnation tank, and the bubbles in the resin melt and the prepreg are rapidly disintegrated or floated up and discharged under the action of ultrasonic cavitation effect through ultrasonic vibration, while reducing the viscosity of the resin, improving its fluidity, allowing it to more fully penetrate between the carbon fiber bundles, thereby improving the impregnation uniformity and interface bonding quality.

[0034] Optionally, the melt impregnation device of the continuous fiber reinforced thermoplastic composite material includes a post-processing mechanism, which is connected to the prepreg outlet of the lower mold impregnation tank, and a product outlet is arranged on the opposite side of the prepreg outlet, and a plurality of upper and lower pairs of extrusion rollers are arranged between the prepreg outlet and the prepreg outlet, and an electromagnetic heating or electric heating device is installed inside the extrusion roller, which is driven by an external motor, and its extrusion gap is used to control the thickness of the prepreg. As the gap between the extrusion rollers decreases step by step, the resin content and thickness of the prepreg gradually decrease, and a product with a set fiber and resin ratio is obtained.

[0035] Optionally, the post-processing mechanism is provided with a heating tube for maintaining the chamber temperature; the post-processing mechanism is provided with a radiation heater for ensuring that the prepreg resin matrix does not solidify during the extrusion process.

[0036] Optionally, the post-processing mechanism is provided with a temperature sensor, and the temperature sensor is connected to the heating device. When the temperature in the cavity deviates from the set temperature range, the sensor transmits a signal and the heating device is turned on or off.

[0037] A method for melt impregnation of a continuous fiber reinforced thermoplastic composite material based on the above-mentioned melt impregnation device for a continuous fiber reinforced thermoplastic composite material comprises the following steps: S1. Adjust the support block and the variable diameter impregnation roller to the set height; S2, the continuous fiber bundle is introduced into the impregnation tank through the fiber inlet, and after being guided and unfolded by the fiber guide column, the support block and the variable diameter impregnation roller, it passes through the impregnation tank through the prepreg outlet; S3, closing the upper mold cover plate and the lower mold dipping tank, raising the temperature and injecting the high-temperature resin melt into the lower mold dipping tank to a set liquid level; S4. The continuous fibers are pulled through a pulling device to complete the impregnation.

[0038] Optionally, in S2, the fibers in the continuous fiber bundle are laid flat on a variable diameter impregnation roller and pass around a fiber guide column in different lateral directions.

[0039] Optionally, in S3, the melt level height is detected and controlled by a liquid level sensor, and the ultrasonic vibration mechanism and the heating tube are started.

[0040] Optionally, in S4, the impregnated fiber bundle passing through the prepreg outlet of the lower mold impregnation tank is passed between the squeezing rollers in the post-processing mechanism, and the impregnated fiber bundle is squeezed to a set thickness by the squeezing rollers, and then discharged from the product outlet.

[0041] Optionally, the high-temperature resin melt is a thermoplastic resin, including one or more of polyetheretherketone (PEEK), polyphenylene sulfide (PPS), low molecular weight polyaryletherketone (LM-PAEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyetherketone (PEK) or polyamide (PA).

[0042] Optionally, the continuous fiber includes one or more of carbon fiber, basalt fiber, aramid fiber, graphite fiber, glass fiber, ceramic fiber, boron fiber, polyamide fiber, polyethylene fiber, PBO fiber, polyester fiber or natural fiber.

[0043] Example 1 The existing problems in the design of continuous fiber reinforced thermoplastic resin melt impregnation equipment include: 1. The fibers are obviously broken and hung, resulting in the accumulation of resin and broken fibers, affecting the normal transmission of the fibers and the stable operation of the impregnation, and even clogging the mold; 2. The fibers are prone to aggregation and twisting. After the fibers are unfolded, they re-aggregate or twist during the impregnation process, reducing the fiber distribution uniformity and performance stability of the prepreg; 3. The thickness consistency of the prepreg is poor, the resin content is unstable, and the surface of the prepreg is rough.

[0044] This embodiment provides a melt impregnation device for continuous fiber reinforced thermoplastic composite materials, such as Figure 1 As shown, it includes an upper mold cover plate 1 and a lower mold dipping tank 2; The lower mold impregnation tank 2 is provided with a fiber inlet 11 and a prepreg outlet 12, and a plurality of variable diameter impregnation rollers 3 are provided between the fiber inlet 11 and the prepreg outlet 12. The axial direction of the variable diameter impregnation rollers 3 is horizontal and perpendicular to the axial direction of the continuous fiber 13 (i.e., the fiber conveying direction). Figure 2 As shown, the two ends of the variable diameter impregnation roller 3 are respectively a large diameter end and a small diameter end, and the large diameter end and the small diameter end are connected by a smooth roller surface, as shown in FIG. Figure 3 As shown, the small diameter ends of adjacent variable diameter impregnation rollers 3 face opposite directions; since the roller surface forms an inclined surface, the fiber tension is small at the position where the roller surface height is low, and the fiber tension is large at the position where the roller surface height is high, and the unfolded continuous fiber 13 passes through the large diameter end and the small diameter end in turn to keep the tension uniform; if the continuous fiber 13 breaks during the transmission process, the fiber tension is uneven, which in turn causes the broken fibers to move to the small diameter end and finally gather on one side of the small diameter end, thereby collecting the broken fibers and avoiding the accumulation of several broken fibers.

[0045] like Figure 1As shown, the upper mold cover plate 1 covers the lower mold impregnation tank 2, and the upper mold cover plate 1 is provided with a plurality of downward support blocks 4, the support blocks 4 are located between adjacent variable diameter impregnation rollers 3, and the lowest point of the support blocks 4 is lower than the highest point of the small diameter end of the variable diameter impregnation roller 3, so the support blocks 4 can press down the continuous fibers 13 stretched on the roller surface, promote the expansion of the continuous fiber bundles, and avoid twisting.

[0046] like Figure 2 As shown, the roller surface of the variable diameter impregnation roller 3 is a straight conical surface, and the variable diameter impregnation roller 3 is externally connected to an external motor. The gears of the rotatable horizontal axes 14 of multiple variable diameter impregnation rollers 3 are connected to an external motor through a chain, and the motor speed is adjustable to achieve synchronous rotation of all variable diameter impregnation rollers 3 during the impregnation process.

[0047] like Figure 4 As shown, the profile of the support block 4 is the same as the roller surface profile of the variable diameter impregnation roller 3, so that the gap between the surface of the support block 4 and the roller surface forms a channel of equal width, and the gap is set to 0.3mm. The specific value of the gap depends on the resin melt viscosity, fiber diameter and the number of monofilaments. It is required to further expand the fiber and provide a better impregnation effect, while preventing the twisted fiber from passing through. Since the surface of the support block 4 is smooth and does not rotate, it can apply resistance to the twisted position to prevent it from passing through the channel; Figure 5 As shown, the support blocks 4 are installed on the upper mold cover plate 1 at a set distance.

[0048] like Figure 1 As shown, a fiber guide column 5 is provided in the lower mold impregnation tank 2, and the height of the fiber guide column 5 is higher than the roller surface of the variable diameter impregnation roller 3, and the variable diameter impregnation roller 3 is located between the fiber guide column 5 and the support block 4. The existence of the fiber guide column 5 increases the constraint degree on the continuous fiber 13 in the horizontal direction, stabilizes and optimizes the travel path of the carbon fiber bundle in the impregnation tank, so that it is evenly distributed and evenly stressed during the impregnation process, and extends the impregnation contact length, thereby improving the resin impregnation effect.

[0049] like Figure 1 As shown, the upper mold cover plate 1 is provided with an extruder pouring port 6 and an exhaust port 10. The extruder pouring port 6 is used to convey the high-temperature resin melt to the lower mold immersion tank 2. The exhaust port 10 is used to maintain the air pressure balance in the lower mold immersion tank 2 and discharge the gas generated by the bubbles in the high-temperature resin melt.

[0050] like Figure 1 As shown, the upper mold cover plate 1 is provided with a liquid level sensor, including a first liquid level sensor 71 and a second liquid level sensor 72. The first liquid level sensor 71 is used to set the lower limit of the liquid level, and the second liquid level sensor 72 is used to set the upper limit of the liquid level. The height difference between the first liquid level sensor 71 and the second liquid level sensor 72 is the upper and lower floating range of the liquid level.

[0051] The upper mold cover plate 1 and the lower mold dipping tank 2 are provided with heating pipes 9 for maintaining the temperature of the high-temperature resin melt so that it has higher fluidity and wettability.

[0052] An ultrasonic vibration mechanism 8 is provided in the lower mold impregnation tank 2 for removing bubbles in the high-temperature resin melt. The ultrasonic vibration mechanism 8 is arranged at the center position between two adjacent variable-diameter impregnation rollers 3. Ultrasonic vibration causes the bubbles in the resin melt to quickly disintegrate or float up and be discharged under the action of the ultrasonic cavitation effect, thereby effectively reducing the residual bubbles in the resin and preventing them from entering the fiber prepreg; at the same time, ultrasonic vibration helps to reduce the viscosity of the resin, improve its fluidity, and enable it to more fully penetrate between the carbon fiber bundles, thereby improving the impregnation uniformity and interface bonding quality.

[0053] like Figure 6 As shown, the melt impregnation device of the continuous fiber reinforced thermoplastic composite material includes a post-processing mechanism, which is connected to the prepreg outlet 12 of the lower mold impregnation tank 2, and a product outlet is arranged on the opposite side of the prepreg outlet 12, and a plurality of upper and lower pairs of squeezing rollers 17 are arranged between the prepreg outlet 12 and the prepreg outlet, and the squeezing rollers 17 are used to squeeze out excess molten resin in the prepreg to form a set product thickness and obtain qualified surface quality.

[0054] The post-processing mechanism is also provided with an upper cover plate 15 and a lower chamber 16 which are interlocked with each other. The lower chamber 16 is provided with a heating tube 9, and the upper cover plate 15 is provided with a radiation heater 18. The heating tube 9 is used to maintain the temperature in the cavity of the post-processing mechanism, and the radiation heater 18 is used to perform non-contact heating on the fiber prepreg to keep its resin matrix in a molten or softened state, and cooperate with the squeezing roller 17 with a gradually decreasing gap to reduce and control the thickness of the prepreg, and at the same time reduce and control the resin content in the prepreg, thereby improving the quality stability of the prepreg and optimizing the resin-fiber ratio.

[0055] The method for melt impregnation of a continuous fiber reinforced thermoplastic composite material based on the melt impregnation device for the continuous fiber reinforced thermoplastic composite material of this embodiment comprises the following steps: S1, adjusting the height of the support block 4 and the variable diameter impregnation roller 3 to a set position; S2, the continuous fiber 13 is introduced into the impregnation tank through the fiber inlet 11, and is gradually unfolded and guided by the fiber guide column 5, the support block 4 and the variable diameter impregnation roller 3, as shown in FIG. Figure 3 As shown, the continuous fiber 13 passes over the variable diameter impregnation roller 3 and is pressed down by the support block 4. The continuous fiber 13 bypasses the fiber guide column 5 from the left and right directions, and the continuous fiber 13 is constrained within the set range of the roller surface, and then passes through the impregnation tank through the prepreg outlet 12; S3, closing the upper mold cover plate 1 and the lower mold dipping tank 2, and heating the temperature to the set thermoplastic resin processing temperature through the heating tube 9, and then maintaining it for more than 0.5-2 hours, injecting the high-temperature resin melt into the lower mold dipping tank 2 to the set liquid level, and controlling the melt level height through the liquid level sensor. When the melt height reaches the set height of the high-level liquid level sensor, stop injecting the resin melt and start the ultrasonic vibration mechanism 8; S4. After vibrating for more than 5 to 10 minutes, the fiber traction device externally connected to the rear of the post-processing device and the external motor of the variable diameter impregnation roller 3 in the lower mold impregnation tank 2 are turned on at the same time, and the continuous fiber 13 is pulled through the lower mold impregnation tank 2 by the traction device to complete the impregnation, and the impregnated fiber bundle passing through the prepreg outlet 12 of the lower mold impregnation tank 2 passes between the squeezing rollers 17 in the post-processing mechanism, and the impregnated fiber bundle is squeezed to a set thickness by the squeezing roller 17. During this period, the rotation speed of the squeezing roller 17 is synchronized with the variable diameter impregnation roller 3 and then led out from the product outlet. After winding, a fiber prepreg with uniform thickness, low resin content and high precision is obtained.

[0056] During the process, all broken wires will move toward the small diameter end of the variable diameter impregnation roller 3 to achieve self-cleaning inside the mold. When too many broken wires accumulate, just open the upper mold cover to quickly remove the broken wires on both sides of the impregnation tank.

[0057] Example 2 A high thermal conductivity composite material forming mold, the difference between this embodiment and embodiment 1 is that the shape of the variable diameter impregnation roller 3 is as follows Figure 7 The roller surface shown is an outwardly convex conical surface, and the curvature of the small diameter end is greater than that of the large diameter end. The design of this convex variable diameter impregnation roller 3 can effectively reduce the local tension of the fiber during the impregnation process, improve the degree of fiber expansion on the impregnation roller and the impregnation quality, and is particularly suitable for rapid melt impregnation production.

[0058] Accordingly, the support block 4 is adjusted to Figure 8 The shape can also be Figure 8 As shown, channels of equal width are formed to eliminate twisting; Fig. 9 As shown, the support blocks 4 are installed on the upper mold cover plate 1 at a set distance.

[0059] The path of the continuous fiber 13 in the lower die impregnation tank 2 is as follows: Fig.10 shown.

[0060] In this embodiment, no post-processing mechanism is provided, and the prepreg is discharged from the prepreg outlet 12 of the lower mold impregnation tank 2, and then cooled and rolled up to obtain a prepreg product.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A melt impregnation device for continuous fiber reinforced thermoplastic composite materials, characterized in that: It includes an upper mold cover plate and a lower mold impregnation tank; the lower mold impregnation tank is provided with a fiber inlet and a prepreg outlet, and a plurality of variable diameter impregnation rollers are arranged between the fiber inlet and the prepreg outlet, the axial direction of the variable diameter impregnation roller is horizontal and perpendicular to the fiber axial direction, the two ends of the variable diameter impregnation roller are respectively a large diameter end and a small diameter end, the large diameter end and the small diameter end are connected by a smooth roller surface, and the small diameter ends of adjacent variable diameter impregnation rollers face oppositely; the upper mold cover plate covers above the lower mold impregnation tank, and the upper mold cover plate is provided with a plurality of downward support blocks, the support blocks are located between adjacent variable diameter impregnation rollers, and the lowest point of the support blocks is lower than the highest point of the small diameter end of the variable diameter impregnation roller.

2. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: The roller surface of the variable diameter impregnation roller is a straight conical surface or a convex conical surface.

3. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: The profile of the support block is the same as the profile of the roller surface of the variable diameter impregnation roller, so that the gap between the surface of the support block and the roller surface forms a channel of equal width.

4. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: The upper mold cover plate is provided with an extruder pouring port and an exhaust port.

5. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: The upper mold cover plate is provided with a liquid level sensor and a heating tube, and the lower mold immersion tank is provided with a heating tube and an ultrasonic vibration mechanism.

6. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: A fiber guide column is arranged in the lower mold dipping tank, the height of the fiber guide column is higher than the roller surface of the variable diameter dipping roller, and the variable diameter dipping roller is located between the fiber guide column and the support block.

7. The melt impregnation device for continuous fiber reinforced thermoplastic composite material according to claim 1, characterized in that: It comprises a post-processing mechanism, which is connected to the prepreg outlet of the lower mold dipping tank, and a product outlet is arranged on the opposite side of the prepreg outlet, and a plurality of upper and lower pairs of extrusion rollers are arranged between the prepreg outlet and the prepreg outlet.

8. A method for melt impregnation of continuous fiber reinforced thermoplastic composite materials based on the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Adjust the support block and the variable diameter impregnation roller to the set height; S2, the continuous fiber bundle is introduced into the impregnation tank through the fiber inlet, and after being guided and unfolded by the fiber guide column, the support block and the variable diameter impregnation roller, it passes through the impregnation tank through the prepreg outlet; S3, closing the upper mold cover plate and the lower mold dipping tank, raising the temperature and injecting the high-temperature resin melt into the lower mold dipping tank to a set liquid level; S4. The continuous fibers are pulled through a pulling device to complete the impregnation.

9. The melt impregnation method of continuous fiber reinforced thermoplastic composite material according to claim 8, characterized in that: In S2, the fibers in the continuous fiber bundle are laid flat on the variable diameter impregnation roller and bypass the fiber guide column in different lateral directions; in S3, the melt liquid level height is detected and controlled by the liquid level sensor, and the ultrasonic vibration mechanism and the heating tube are started.

10. The melt impregnation method of continuous fiber reinforced thermoplastic composite material according to claim 8, characterized in that: In S4, the impregnated fiber bundle exiting from the prepreg outlet of the lower die impregnation tank is passed between the squeezing rollers in the post-processing mechanism, and the impregnated fiber bundle is squeezed to a set thickness by the squeezing rollers, and then discharged from the product outlet.

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