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

Abstract

The present invention relates to a melting impregnation device and method for continuous fiber reinforced thermoplastic composites, belonging to the technical field of composite material molding. In the device, the lower die impregnation tank is provided with a fiber inlet and a prepreg outlet. Between the fiber inlet and the prepreg outlet, a plurality of variable-diameter impregnation rollers are arranged. The two ends of the variable-diameter impregnation roller 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. The small-diameter ends of adjacent variable-diameter impregnation rollers face in opposite directions; the die cover plate covers above the lower die impregnation tank, and the upper die 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 block is lower than the highest point of the small-diameter end of the variable-diameter impregnation roller. Through the variable-diameter design of the variable-diameter impregnation roller, in cooperation with the support block and the fiber guiding column, the unfolding effect of the fiber is maintained and improved, effectively solving the problems of fiber breakage, aggregation and twisting, and ensuring the high-quality output of the prepreg.

Description

Technical Field

[0001] The present invention belongs to the technical fields of melt impregnation molds and processes and composite material forming technologies, and particularly relates to a melt impregnation device and method for continuous fiber reinforced thermoplastic composites. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

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

[0004] Currently, the melt impregnation process of continuous fiber reinforced thermoplastic composites generally uses a melt impregnation device equipped with a curved / wavy impregnation runner or multiple columnar impregnation rollers, and improves the impregnation effect through the design of the runner length and structure, the number of impregnation rollers, and the drive principle.

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

[0006] Chinese patents CN111452254A and CN118617630A disclose an impregnation die that forms a W-shaped channel through a fixed impregnation roller. However, due to the large and difficult-to-control fiber tension, this solution is prone to problems such as a decline in fiber dispersion quality, as well as fiber breakage and bending. Chinese patent CN114801254A proposes a melt impregnation die that includes 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 viscosities (such as polyetheretherketone, polyphenylene sulfide, polyetherimide, and polyetherketoneketone, etc.), such cylindrical impregnation rollers still cause obvious problems such as fiber breakage, twisting, and aggregation, affecting the impregnation quality and the thickness consistency of the prepreg. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a melt impregnation device and method for continuous fiber-reinforced thermoplastic composites, which utilize a variable-diameter impregnation roller and related devices to further unfold the fibers during the melt impregnation process, effectively reduce the phenomena of fiber breakage, hanging, and entanglement, and have a function of self-cleaning broken filaments, thereby significantly improving the impregnation quality and production efficiency of fiber-reinforced thermoplastic composite prepregs.

[0008] To achieve the above purpose, the technical solution of the present invention is as follows:

[0009] In the first aspect, a melt impregnation device for continuous fiber-reinforced thermoplastic composites includes an upper die cover plate and a lower die impregnation tank;

[0010] The lower die impregnation tank is provided with a fiber inlet and a prepreg outlet. Between the fiber inlet and the prepreg outlet, a plurality of variable-diameter impregnation rollers are arranged. The axial direction of the variable-diameter impregnation roller is horizontal and perpendicular to the fiber axis. The two ends of the variable-diameter impregnation roller 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. The small-diameter ends of adjacent variable-diameter impregnation rollers face opposite directions;

[0011] The upper die cover plate covers the upper part of the lower die impregnation tank. The upper die 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 block is lower than the highest point of the small-diameter end of the variable-diameter impregnation roller.

[0012] In the second aspect, a melt impregnation method for continuous fiber-reinforced thermoplastic composites based on the above device includes the following steps:

[0013] S1. Adjust the support block and the variable-diameter impregnation roller to the set height;

[0014] S2. The continuous fiber bundle is introduced into the impregnation tank through the fiber inlet, and after being guided and unfolded by the fiber guiding column, the support block, and the variable-diameter impregnation roller, it passes through the prepreg outlet and exits the impregnation tank;

[0015] 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;

[0016] S4. The continuous fibers are pulled through a pulling device to complete the impregnation.

[0017] The beneficial effects of the present invention are:

[0018] 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

[0019] 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.

[0020] Figure 1 This is a schematic structural diagram of the melt impregnation device of the continuous fiber reinforced thermoplastic composite material in Example 1.

[0021] Figure 2 This is a schematic diagram of the structure of the variable diameter impregnation roller in Example 1.

[0022] Figure 3 This is a guide path diagram of the continuous fiber in Example 1.

[0023] Figure 4 Schematic diagram of the outline of the support block in Example 1.

[0024] Figure 5 This is a schematic diagram of the installation of the support block in Example 1.

[0025] Figure 6 Schematic diagram of the structure of the post-processing mechanism in Example 1.

[0026] Figure 7 This is a schematic diagram of the structure of the variable diameter impregnation roller in Example 2.

[0027] Figure 8Schematic diagram of the contour of the support block in Embodiment 2.

[0028] Figure 9 Schematic diagram of the installation of the support block in Embodiment 2.

[0029] Figure 10 Guiding path diagram of continuous fibers in Embodiment 2.

[0030] Wherein, 1. Upper die cover plate; 2. Lower die impregnation tank; 3. Variable-diameter impregnation roller; 4. Support block; 5. Fiber guiding 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 shaft; 15. Upper cover plate; 16. Lower chamber; 17. Squeezing roller; 18. Radiation heater. Detailed implementation manners

[0031] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0032] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the 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 "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] A melting impregnation device for continuous fiber reinforced thermoplastic composites, comprising an upper die cover plate and a lower die impregnation tank;

[0034] The lower die impregnation tank is provided with a fiber inlet and a prepreg outlet. Between the fiber inlet and the prepreg outlet, a plurality of variable-diameter impregnation rollers are arranged. The axial direction of the variable-diameter impregnation roller is horizontal and perpendicular to the fiber axis. The two ends of the variable-diameter impregnation roller 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. The small-diameter ends of adjacent variable-diameter impregnation rollers face in opposite directions;

[0035] The upper die cover plate covers above the lower die impregnation tank. The upper die 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 block is lower than the highest point of the small-diameter end of the variable-diameter impregnation roller.

[0036] In the above settings, the support block can effectively adjust the tension of continuous fibers, and the variable-diameter impregnation roller can further spread the fiber yarns, thereby improving the impregnation effect and uniformity. When a filament break occurs, the broken fibers can be collected at the small-diameter end of the variable-diameter impregnation, realizing the self-cleaning function, thus eliminating the broken filaments in the prepreg product and preventing the impregnation device from being blocked.

[0037] Optionally, the roller surface of the variable-diameter impregnation roller is a flat conical surface or a convex conical surface. On the one hand, this configuration of the impregnation roller can improve the yarn spreading effect and realize the self-cleaning function of filament break. And compared with a cylindrical impregnation roller, under the same impregnation tank length, the fiber tension is effectively reduced, thereby improving the impregnation effect and efficiency.

[0038] Optionally, the contour of the support block is the same as the roller surface contour of the variable-diameter impregnation roller, so that the gap between the surface of the support block and the roller surface forms a channel with an equal width, which promotes the fiber bundle passing through to unfold along the roller surface and prevents it from twisting through. The gap size is between 0.1 - 0.7 mm.

[0039] Optionally, the upper die cover plate is provided with an extruder pouring port for supplementing the melt into the lower die impregnation tank; the upper die cover plate is provided with an exhaust port for exhausting the gas in the die cavity.

[0040] Optionally, the upper die cover plate is provided with a liquid level sensor. When the resin melt liquid level in the lower die impregnation tank is lower than the lowest set value, the low-level sensor sends a signal to the extruder connected to the die to control the extruder to inject 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 resin melt.

[0041] Optionally, the upper die cover plate is provided with heating tubes, which are evenly embedded in the upper die cover plate, and their on-off states are controlled by temperature sensors in the lower die impregnation tank, for maintaining the stable temperature of the resin melt.

[0042] Optionally, fiber guiding columns are arranged in the lower die impregnation tank. The height of the fiber guiding columns is higher than the roller surface of the variable-diameter impregnation roller, and the variable-diameter impregnation roller is located between the fiber guiding columns and the support block; the fiber guiding columns are designed in non-rotating and rotatable adjustable modes. In the non-rotating mode, the tension during the fiber impregnation process can be increased.

[0043] Optionally, heating tubes are arranged in the lower die impregnation tank, and the heating tubes are dispersedly arranged on the entire tank wall for uniformly heating the resin melt to maintain a constant temperature; an ultrasonic vibration mechanism is arranged in the lower die impregnation tank. Through ultrasonic vibration, the bubbles in the resin melt and in the prepreg quickly collapse or float and discharge under the action of the ultrasonic cavitation effect. At the same time, the viscosity of the resin is reduced, its fluidity is improved, and it can penetrate more fully between the carbon fiber bundles, improving the impregnation uniformity and the interface bonding quality.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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:

[0048] S1. Adjust the support block and the variable diameter impregnation roller to the set height;

[0049] 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;

[0050] 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;

[0051] S4. The continuous fibers are pulled through a pulling device to complete the impregnation.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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).

[0056] 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.

[0057] Example 1

[0058] Problems existing in the design of existing continuous fiber reinforced thermoplastic resin melt impregnation devices include: 1. Obvious fiber breakage and hanging occur, resulting in resin and broken wire accumulation, affecting the normal transmission of fibers and the stable operation of impregnation, and even clogging the mold; 2. Fibers are prone to aggregation and twisting, and re-aggregation or twisting occurs during the impregnation process after the fibers are unfolded, 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.

[0059] A melt impregnation device for continuous fiber reinforced thermoplastic composites provided in this example, as Figure 1 shown, includes an upper mold cover plate 1 and a lower mold impregnation tank 2;

[0060] The lower mold impregnation tank 2 is provided with a fiber inlet 11 and a prepreg outlet 12. Between the fiber inlet 11 and the prepreg outlet 12, a plurality of variable-diameter impregnation rollers 3 are provided. 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). As Figure 2 shown, both ends of the variable-diameter impregnation roller 3 are 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 Figure 3 shown, the small-diameter ends of adjacent variable-diameter impregnation rollers 3 face in opposite directions; due to the inclined surface formed by the roller surface, the fiber tension is small at the position with a low roller surface height, and the fiber tension is large at the position with a high roller surface height. And the unfolded continuous fiber 13 passes through the large-diameter end and the small-diameter end in sequence to keep the tension uniform; if the continuous fiber 13 breaks during the transmission process, the fiber tension will be uneven, which will then cause the broken fiber to move towards the small-diameter end, and finally gather on one side of the small-diameter end, realizing the collection of broken fibers and avoiding the accumulation of broken filaments.

[0061] As Figure 1As shown, the upper die cover plate 1 covers above the lower die impregnation tank 2. The upper die 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 rollers 3. Therefore, the support blocks 4 can press down the continuous fibers 13 tightened on the roller surface, promoting the unfolding of the continuous fiber bundle and avoiding the twisting phenomenon.

[0062] As Figure 2 shown, the roller surface of the variable-diameter impregnation roller 3 is a flat conical surface, and the variable-diameter impregnation roller 3 is externally connected to an external motor. The gears of the rotatable horizontal shafts 14 of the plurality of variable-diameter impregnation rollers 3 are connected to an external motor through a chain, and the motor speed is adjustable to achieve the synchronous rotation of all the variable-diameter impregnation rollers 3 during the impregnation process.

[0063] As Figure 4 shown, the contour of the support block 4 is the same as the roller surface contour 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 with an equal width. The gap is set to 0.3 mm, and the specific value of the gap depends on the resin melt viscosity, fiber diameter, and number of filaments. It is required to enable the fibers to further unfold and give a better impregnation effect, and at the same time can prevent the twisted fibers from passing through. And because the surface of the support block 4 is smooth and does not rotate, it can apply resistance to the twisting position to prevent it from passing through this channel; As Figure 5 shown, the support blocks 4 are installed on the upper die cover plate 1 at a set interval.

[0064] As Figure 1 shown, fiber guiding columns 5 are arranged in the lower die impregnation tank 2. The height of the fiber guiding columns 5 is higher than the roller surface of the variable-diameter impregnation rollers 3, and the variable-diameter impregnation rollers 3 are located between the fiber guiding columns 5 and the support blocks 4. The presence of the fiber guiding columns 5 increases the degree of constraint on the continuous fibers 13 in the horizontal direction, stabilizes and optimizes the traveling path of the carbon fiber bundle in the impregnation tank, makes it evenly distributed and evenly stressed during the impregnation process, and prolongs the impregnation contact length, thereby improving the resin infiltration effect.

[0065] As Figure 1 shown, the upper die 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 into the lower die impregnation tank 2, and the exhaust port 10 is used to maintain the air pressure balance in the lower die impregnation tank 2 and discharge the gas generated by the bubbles in the high-temperature resin melt.

[0066] As Figure 1 shown, the upper die cover plate 1 is provided with liquid level sensors, 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.

[0067] A heating tube 9 is provided in the upper die cover plate 1 and the lower die impregnation tank 2 to maintain the temperature of the high-temperature resin melt, so that it has high fluidity and wettability.

[0068] An ultrasonic vibration mechanism 8 is provided in the lower die impregnation tank 2 to remove bubbles in the high-temperature resin melt. The ultrasonic vibration mechanism 8 is arranged at the central position between two adjacent variable-diameter impregnation rollers 3. Under the action of the ultrasonic cavitation effect, the bubbles in the resin melt quickly disintegrate or float up and are discharged, effectively reducing the residual bubbles in the resin and preventing them from entering the fiber pre-preg; at the same time, the ultrasonic vibration helps to reduce the viscosity of the resin, improve its fluidity, make it penetrate more fully between the carbon fiber bundles, and improve the impregnation uniformity and interface bonding quality.

[0069] As Figure 6 shown, the melting impregnation device for continuous fiber reinforced thermoplastic composites includes a post-treatment mechanism. The post-treatment mechanism is communicated with the pre-preg outlet 12 of the lower die impregnation tank 2, and a product outlet is arranged on the opposite side of the pre-preg outlet 12. A plurality of upper and lower paired extrusion rollers 17 are arranged between the pre-preg outlet 12 and the pre-preg outlet. The extrusion rollers 17 are used to extrude the excess molten resin in the pre-preg to form a set product thickness and obtain qualified surface quality.

[0070] The post-treatment mechanism is also provided with a buckled upper cover plate 15 and a lower chamber 16. A heating tube 9 is provided in the lower chamber 16, and a radiation heater 18 is provided on the upper cover plate 15. The heating tube 9 is used to maintain the temperature in the cavity of the post-treatment mechanism, and the radiation heater 18 is used to perform non-contact heating on the fiber pre-preg to keep its resin matrix in a molten or softened state. In cooperation with the extrusion rollers 17 with gradually decreasing gaps, the thickness of the pre-preg is reduced and controlled, and at the same time, the resin content in the pre-preg is reduced and controlled, thereby improving the quality stability of the pre-preg and optimizing the resin-fiber ratio.

[0071] The melting impregnation method of continuous fiber reinforced thermoplastic composites based on the melting impregnation device of continuous fiber reinforced thermoplastic composites in this embodiment includes the following steps:

[0072] S1. Adjust the heights of the support block 4 and the variable-diameter impregnation roller 3 to the set positions;

[0073] 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 post 5, the support block 4 and the variable-diameter impregnation roller 3. As Figure 3 shown, the continuous fiber 13 passes above the variable-diameter impregnation roller 3 and is pressed down by the support block 4. The continuous fiber 13 bypasses the fiber guide post 5 from the left and right directions respectively, constraining the continuous fiber 13 within the set range on the roller surface, and then passing through the pre-preg outlet 12 to exit the impregnation tank;

[0074] 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;

[0075] 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.

[0076] 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.

[0077] Example 2

[0078] 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.

[0079] 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; Figure 9 As shown, the support blocks 4 are installed on the upper mold cover plate 1 at a set distance.

[0080] The path of the continuous fiber 13 in the lower die impregnation tank 2 is as follows: Figure 10 shown.

[0081] 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.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A melt impregnation device for continuous fiber reinforced thermoplastic composite materials, characterized in that: It 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, a plurality of variable diameter impregnation rollers are provided 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, 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; A fiber guide column is arranged 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, so as to make the fibers in the continuous fiber bundle be flatly laid on the variable diameter impregnation roller and bypass the fiber guide column in different lateral directions.

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: 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.

7. A method for melt impregnation of continuous fiber reinforced thermoplastic composite materials based on the device according to any one of claims 1 to 6, 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.

8. The melt impregnation method of continuous fiber reinforced thermoplastic composite material according to claim 7, 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.

9. The melt impregnation method of continuous fiber reinforced thermoplastic composite material according to claim 7, 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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