Multi-stage dipping compression molding equipment and operation method thereof

Abstract

The invention discloses multi-stage impregnation compression molding equipment and an operation method thereof. The multi-stage impregnation compression molding equipment comprises a preheating dehumidification module, an impregnation module, a fiber thickening and layering module, a traction conveying module, a fixed-length cutting module and a mixing conveying module, and is further provided with a compression molding shaping module, a PLC control module and a supporting structure; the PLC control module achieves linkage control over the temperature, the pressure, the traction speed and the cutting length of all the areas. The preheating dehumidification module comprises a preheating flow channel and a heating bin, and a far infrared heating assembly and a humidity detection module are arranged in the heating bin; the dipping module comprises a resin state change adjusting area on the front side, a material injection module on the side face and a plurality of temperature area adjusting mechanisms arranged front and back. The fiber thickening layer laying module comprises an upper layer laying module and a lower layer laying module, a plurality of material injection structures are arranged on the side face of the fiber thickening layer laying module, and a yarn splitting thickening structure and a fiber thickening layer laying runner are arranged between the upper layer laying module and the lower layer laying module.

Description

Technical Field

[0001] This invention relates to the field of thermoplastic composite material production equipment technology, specifically to a multi-stage impregnation molding equipment and its operation method. Background Technology

[0002] Long fiber reinforced thermoplastic composites are increasingly widely used in the automotive, aerospace, and electronics industries due to their lightweight, high stiffness, high toughness, and environmental friendliness. The core requirement for the preparation of these composites is to achieve thorough impregnation of the fibers with the thermoplastic resin while preserving as much fiber length as possible to ensure the mechanical properties of the finished product.

[0003] Existing thermoplastic continuous fiber composite material production equipment has several drawbacks: First, the impregnation process is simplistic, with most equipment employing only single-stage melt impregnation or coating impregnation. For example, the long fiber reinforced thermoplastic composite material production equipment disclosed in patent CN214395511U achieves single-stage composite pressing of the melt and long fibers through a die body, which easily leads to insufficient bonding between the fiber and resin, resulting in high internal porosity and limited mechanical properties in the product. Second, the bonding process for converting continuous fibers to fixed long fibers is immature. Some equipment, such as the pultrusion molding equipment in CN111619142A, cuts the fiber strip after continuous molding without surface pretreatment before cutting, leading to… The following issues arise: First, the fiber ends are prone to fuzzing and have poor length accuracy after cutting. Second, there is a lack of targeted secondary impregnation after cutting, resulting in insufficient interfacial bonding between the fiber and the resin. Third, the traction device has poor adaptability. Existing traction structures are mostly designed with fixed gaps, which cannot meet the production needs of fiber strips of different thicknesses. Furthermore, the traction process can easily cause tensile damage to the fibers. Fourth, the screw stirring mechanism is poorly designed. Traditional screw extrusion devices combine extrusion and stirring functions. When processing long fibers, they are prone to breaking the fibers, reducing the reinforcing effect of the composite material. For example, some molding compound production devices produce granules by extruding, melting, impregnating, and then cutting them. This results in severe fiber length loss, making it difficult to guarantee the mechanical properties of the molded products.

[0004] Furthermore, existing technologies lack a coordinated design for the entire process of "continuous multi-stage fiber impregnation - precise traction - fixed-length cutting - gentle stirring." Independent operation of each stage easily leads to problems such as low production efficiency, high material loss, and unstable product quality. For example, while some devices achieve continuous impregnation and cutting, the resin coating on the fiber surface is uneven after cutting, resulting in a high fiber breakage rate during subsequent stirring. Other devices use a die to guide the fiber and melt for composite bonding, but cannot achieve layered injection and precise sealing of resins with different properties, limiting the functional expansion of composite materials. Therefore, developing an integrated production device that combines sufficient impregnation, precise traction and fixed length, low fiber damage, and high adaptability is key to overcoming the bottlenecks of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing thermoplastic continuous fiber composite material production devices, such as insufficient impregnation, poor connection between continuous and fixed length transitions, weak traction adaptability, easy fiber breakage, and unstable product quality, this invention provides a direct compression molding equipment for long fiber multi-stage impregnation thermoplastic composite materials. This equipment achieves precise control and multi-stage sufficient impregnation throughout the continuous fiber process, reduces fiber damage, and improves product performance.

[0006] A multi-stage impregnation and molding equipment includes a preheating and dehumidification module, an impregnation module, a fiber thickening and layup module, a traction conveying module, a fixed-length cutting module, and a mixing and conveying module. It also includes a molding and shaping module, a PLC control module, and a support structure. The impregnation module, fiber thickening and layup module, and traction conveying module form a continuous fiber three-stage impregnation process system, while the fixed-length cutting module, mixing and conveying module, and molding and shaping module form a long fiber fixed-length cutting and molding process system. The PLC control module enables coordinated control of temperature, pressure, traction speed, and cutting length in each zone.

[0007] The preheating and dehumidification module includes a preheating channel and a heating chamber. The heating chamber is equipped with a far-infrared heating component and a humidity detection module. The preheating channel has a rectangular structure, runs through the heating chamber, and has a split-type visual observation module at the top.

[0008] The impregnation module includes a resin phase change adjustment zone on the front, a filling module on the side, and several temperature zone adjustment mechanisms arranged at the front and rear. A heat insulation device is arranged between the several temperature zone adjustment mechanism zones, and a heating device is arranged inside the temperature zone adjustment mechanism.

[0009] The fiber thickening layup module includes an upper layup module and a lower layup module. Multiple injection structures are provided on the side of the fiber thickening layup module. A yarn splitting thickening structure and a fiber thickening layup flow channel are provided between the upper layup module and the lower layup module. Several levels of yarn splitting structures are provided in the fiber thickening layup flow channel along the direction of travel. The number of yarn splitting layers in each level of the yarn splitting structure increases progressively and the width decreases progressively along the fiber travel direction, so as to achieve precise adjustment of the transverse width and longitudinal number of layers of the fiber yarn.

[0010] The traction conveying module includes a central main roller, an impregnation cavity surrounding the main roller, and several distribution rollers arranged around the main roller within the impregnation cavity. A gap adjustment structure is provided between the corresponding distribution rollers to adjust the gap between the distribution rollers and the main roller. The traction conveying module also includes support structures on both sides and at the bottom. An impregnation outlet is provided at the bottom of the impregnation cavity. Several circumferential heating devices are provided inside the main roller. An active traction impregnation drive device is connected to the main roller, and a driven traction impregnation drive device is connected to the distribution rollers.

[0011] The fixed-length cutting module is installed inside the outlet of the impregnated product. The fixed-length cutting module includes a fixed-length cutting roller at the front end and a driven cutting roller. The fixed-length cutting roller is connected to the fixed-length cutting power adjustment device, and a visual inspection device is installed at the cutting and dropping point.

[0012] The hybrid conveying module includes a distributed screw combined conveying structure, a hybrid conveying drive device, and an outer circumferential temperature regulating device. The distributed screw combined conveying structure includes a fiber composite material flow cavity and a screw disposed inside the fiber composite material flow cavity.

[0013] The continuous fiber three-stage impregnation process system, consisting of the impregnation module, the fiber thickening layup module, and the traction conveying module, includes three stages: basic impregnation by the impregnation module, layered impregnation by the fiber thickening layup module, and deep impregnation by the traction conveying module.

[0014] The high gradient temperature zone adjustment mechanism in the impregnation module has a temperature adjustment range of 200-300℃. The temperature adjustment is achieved by a combination of the high gradient temperature zone heating device and the PLC control module. The low gradient temperature zone adjustment mechanism is used to cool the fiber & resin composite material initially impregnated by the high gradient temperature zone adjustment mechanism to the high elastic state of its resin matrix, enabling it to flexibly transition between the glassy state and the high elastic state.

[0015] The fiber thickening layup module has a rectangular structure, with a second injection structure for resin injection on the side of the inlet end and a third injection structure for resin injection on the side of the outlet end. The injection ports of both the second and third injection structures have equal diameter and continuous cross-sections. The high-elasticity composite material formed by the low gradient temperature zone adjustment mechanism is used to seal the resin injected by the second injection structure. The yarn thickening structure uses a three-dimensional weaving method to form a three-dimensional interwoven structure of fibers in the longitudinal space, realizing the gradient layup preforming of the fiber-resin composite material in the fiber thickening layup channel.

[0016] The gap between the main roller and the distribution roller is adjustable from 0 to 6 mm. The main roller and the distribution roller are used to pull, impregnate and compact the composite strip from the fiber thickening layup module. The circumferential heating structure is located around the main roller and fixed to the support mechanism on both sides.

[0017] The screw in the distributed screw assembly conveying structure is a constant-depth screw with a pitch that gradually decreases along the conveying direction. The top of its screw ridges is provided with a continuous scraping groove. It is a structure that mainly conveys and distributes mixing while weakening the shearing effect. It is used to melt, finally impregnate and convey the long fiber composite material of equal length and width cut by the fixed-length cutting structure.

[0018] The fixed-length cutting roller is coated with diamond; the fixed-length power adjustment device is a servo-synchronous electric device and uses an external gear structure to synchronously control the fixed-length cutting roller and the driven cutting roller. The cutting length is adjusted online by the rotation speed, and the control range is 16-20mm.

[0019] The main roller and the distribution roller are shaft structures with an elastic coating, which is made of high-temperature resistant polytetrafluoroethylene composite material. The vision inspection module performs real-time detection on the fiber length and surface flatness after fixed-length cutting, and automatically stops the machine for adjustment when abnormalities occur.

[0020] The operation method of the above-mentioned multi-stage dip molding equipment includes the following steps:

[0021] Step 1: After the continuous fiber yarn bundle is preheated and dehumidified, it enters the high gradient temperature zone adjustment mechanism and is initially impregnated with the first type of resin melt injected by the first injection structure to obtain the preliminary impregnated material;

[0022] Step 2: The initially impregnated material enters the low-gradient temperature zone regulating mechanism and is converted and cooled to the high-elasticity state of the resin matrix;

[0023] Step 3: Within the fiber thickening layup module, the thickness of the fiber resin composite material is longitudinally increased within a single bundle of fibers in the fiber resin composite tape by mechanical means. At the same time, a second resin and a third resin can be selectively injected through the second injection structure and the third injection structure.

[0024] Step 4: The continuous strip, after being pulled, impregnated, and compacted by the traction conveyor module, is cut into long fiber segments with a length range of 16-20mm.

[0025] Step 5: The long fiber segments enter the mixing and conveying module, where they are melted, impregnated, and finally conveyed to the molding and shaping module to be pressed into products under the action of stirring and conveying.

[0026] Compared with the prior art, the present invention has the following significant advantages:

[0027] Multi-stage impregnation synergistic design significantly improves impregnation adequacy: This invention solves the problem of insufficient single-stage impregnation in existing technologies by employing a three-stage impregnation system: a fiber preheating and dehumidification module for dehumidifying and preheating dispersed fiber yarns, a basic impregnation module and a layered impregnation module for fiber thickening and layering, and a deep impregnation module for traction and conveying. The preheating and dehumidification module reduces fiber moisture content and decreases porosity after mixing; the separate heating and cooling control of the impregnation module ensures both sufficient basic impregnation and precise sealing and layered injection of resins with different properties; the dedicated stirring screw in the mixing and conveying module completes deep impregnation while avoiding fiber breakage, resulting in a final product porosity of less than 1.5%, which is more than 60% lower than existing devices.

[0028] Improved cutting flatness; the fixed-length cutting roller adopts servo control, and the cutting length accuracy error is ≤±0.2mm, which greatly improves the cutting efficiency; the mixing and conveying module adopts a shear-free stirring screw, and the fiber breakage rate is controlled within 3%, which is more than 40% higher than the fiber length retention rate of traditional screw extrusion devices, significantly improving the mechanical properties of the product.

[0029] Strong traction adaptability and compatibility with multi-specification production: The traction conveying module adopts a traction structure that combines the main roller with the surrounding distribution rollers. With the gap adjustment design between the main roller and the distribution rollers, it can adapt to the conveying needs of fiber strips with different thicknesses from 0 to 6 mm without the need to replace the traction components. At the same time, the elastically wrapped shaft structure of the main roller and distribution rollers can avoid damage to the fiber strips during traction and ensure conveying stability.

[0030] Integrated design improves production efficiency and reduces costs: This invention realizes an integrated design for the entire process from continuous fiber pretreatment, multi-stage impregnation, precise traction, fixed-length cutting to stirring and molding, with coordinated control of each link, improving production efficiency by more than 30% compared to existing segmented devices; the multi-performance resin injection design of the fiber thickening layup module can realize the production of multi-performance gradient composite materials with a single set of devices without the need to change the production line, which greatly reduces production costs. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 This is a schematic cross-sectional view of the overall structure of the present invention;

[0033] Figure 3 This is a top view of the overall structure of the present invention.

[0034] Figure 4 This is an enlarged schematic diagram of region A of the cross-sectional structure of the present invention;

[0035] Figure 5 This is a schematic cross-sectional view of the fiber layup module of the present invention;

[0036] Figure 6 This is a schematic diagram of the distributed screw structure of the present invention;

[0037] Figure 7 This is a schematic diagram of the first-stage yarn splitting structure of the present invention;

[0038] Figure 8 This is a schematic diagram of the second-stage yarn splitting structure of the present invention;

[0039] Figure 9 This is a schematic diagram of the third-stage yarn splitting structure of the present invention;

[0040] Figure 10 This is a schematic diagram of the fourth-stage yarn splitting structure of the present invention;

[0041] Figure 11 This is a schematic diagram of the fifth-stage yarn splitting structure of the present invention;

[0042] In the diagram, 1. Preheating and dehumidification module; 11. Preheating channel; 12. Heating chamber; 13. Far-infrared heating component; 14. Humidity monitoring module; 2. Impregnation module; 21. Injection structure; 211. First injection structure; 212. Injection channel; 22. Resin physical state change adjustment zone; 221. Fluid circulation chamber; 222. Resin physical state adjustment channel; 23. High gradient temperature zone adjustment mechanism; 24. Low gradient temperature zone adjustment mechanism; 25. Split-type heat insulation connection device; 26. High gradient temperature zone heating device; 27. Low gradient temperature zone heating device; 3. Fiber thickening layup module; 31. Upper layup structure; 32. Lower layup structure; 33. Second injection structure; 34. Third injection structure; 35. Yarn splitting thickening structure; 351. First-stage yarn splitting structure; 352. Second-stage yarn splitting structure; 3 53. Third-stage yarn splitting structure; 354. Fourth-stage yarn splitting structure; 355. Fifth-stage yarn splitting structure; 36. Fiber thickening and layering flow channel; 4. Traction conveying module; 41. Main roller; 42. Distribution roller; 43. Impregnation chamber; 44. Gap adjustment structure; 45. Support structure; 46. Circumferential heating device; 47. Active traction impregnation drive device; 48. Driven traction impregnation drive device; 49. Impregnated product outlet; 5. Fixed-length cutting module; 51. Fixed-length cutting roller; 52. Driven cutting roller; 53. Fixed-length cutting power adjustment device; 54. Vision inspection device; 6. Mixed conveying module; 61. Distributed screw combined conveying structure; 62. Mixed conveying drive device; 63. Mixed conveying temperature adjustment device; 64. Guide channel; 7. Molding and shaping module; 8. PLC control module. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention.

[0044] Example 1: A multi-stage impregnation molding equipment, mainly used for direct molding of long fiber multi-stage impregnation thermoplastic composite materials, such as... Figure 1 As shown, it includes a preheating and dehumidification module 1, an impregnation module 2, a fiber thickening and layering module 3, a traction conveying module 4, a fixed-length cutting module 5, a mixing and conveying module 6, and also includes a molding and shaping module 7, a PLC control module 8, and a support structure; the fixed-length cutting module 5, the mixing and conveying module 6, and the molding and shaping module 7 constitute a long fiber fixed-length cutting and forming process system.

[0045] Because this device is composed of interconnected modules, each module functions independently. To facilitate understanding of this technical solution by those skilled in the art, the structure and independent operation of each module are described below:

[0046] like Figure 1 As shown, the continuous fiber three-stage impregnation process system consists of impregnation module 2, fiber thickening layup module 3, and traction conveying module 4. The process system includes three stages: basic impregnation of impregnation module 2, layered impregnation of fiber thickening layup module 3, and deep impregnation of traction impregnation conveying module 4.

[0047] like Figure 4 As shown, the preheating and dehumidification module 1 includes a preheating channel 11, a heating chamber 12, a far-infrared heating component 13, and a humidity detection module 14. The preheating channel 11 has a rectangular structure and is located at the upper part of the preheating and dehumidification module 1. The top is a split-type visual observation module, and those skilled in the art can cover this area with high-temperature resistant glass or an equivalent heat-resistant transparent material. The heating chamber 12 is located at the lower part of the preheating and dehumidification module 1. Far-infrared heating components 13 are arranged on both sides, and the humidity detection module 14 is arranged at the bottom. The preheating channel 11 and the heating chamber 12 are either connected or isolated.

[0048] like Figure 2 , Figure 4 As shown, the impregnation module 2 includes a resin state change adjustment zone 22 on the front and an injection structure 21 on the side. The resin state change adjustment zone 22 includes a fluid circulation chamber 221 and a resin state adjustment channel 222. The fluid circulation chamber 221 works together with an external water circulation system and an electric heating device in the resin state adjustment channel 222 to adjust a portion of the resin injected through the injection structure 21 that flows back to a high-elasticity state by adjusting the temperature. This ensures that the fiber yarn can pass through without restriction and that the subsequent resin material will not flow back again.

[0049] The injection structure 21 consists of a first injection structure 211 and an injection channel 212, with the injection channel 212 connected to the channel through which the fiber passes. It also includes a front-to-back separate high-gradient temperature zone adjustment mechanism 23 and a low-gradient temperature zone adjustment mechanism 24, which are thermally insulated from each other by a separate heat insulation device 25. The separate heat insulation device 25 does not affect the lateral flow within the impregnation module 2. A high-gradient temperature zone heating device is provided at the bottom of the high-gradient temperature zone adjustment mechanism 23. The low gradient temperature zone adjustment mechanism 24 is equipped with a low gradient temperature zone heating device 27 at its bottom; the high gradient temperature zone adjustment mechanism 23 in the impregnation module 2 has a temperature adjustment range of 200-300℃, and the temperature adjustment is combined and adjusted by the high gradient temperature zone heating device 26 and the PLC control module 8; the low gradient temperature zone adjustment mechanism 24 is used to cool the fiber & resin composite material initially impregnated by the high gradient temperature zone adjustment mechanism 23 to the high elastic state of its resin matrix, so that it can flexibly switch between the glass state and the high elastic state.

[0050] like Figure 2 As shown, Figure 2, 5 As shown in 7, 8, 9, 10, and 11, the fiber thickening layup module 3 includes an upper layup module 31, a lower layup module 32, a second injection structure 33 and a third injection structure 34 located on the side, a rectangular yarn-splitting thickening structure 35 in the middle, and a fiber thickening layup flow channel 36. The fiber thickening layup flow channel 36 is provided with 5 levels of rectangular yarn-splitting structures along the direction of travel. The number of yarn-splitting layers in each level of the yarn-splitting structure increases progressively along the fiber travel direction, while the width decreases progressively, so as to achieve precise adjustment of the transverse width and longitudinal number of layers of the fiber yarn.

[0051] The fiber thickening layup module 3 has a rectangular structure. Its inlet end has a second injection structure 33 for injecting resin, and its outlet end has a third injection structure 34 for injecting resin. The injection ports of the second injection structure 3 and the third injection structure 34 are both of equal diameter and continuous length. The high-elasticity composite material formed in the low gradient temperature zone adjustment mechanism 24 is used to seal the resin injected by the second injection structure 33. The yarn thickening structure 35 uses a simple three-dimensional weaving method to make the fibers form a three-dimensional interwoven structure in the longitudinal space, so that the fiber resin composite material can complete the gradient layup preforming in the fiber thickening layup channel 36.

[0052] Furthermore, thermoplastic resins with different properties are injected through the second injection structure 33 and the third injection structure 34 located on the side, and then sequentially through the first-level yarn splitting structure 351, the second-level yarn splitting structure 352, the third-level yarn splitting structure 353, the fourth-level yarn splitting structure 354, and the fifth-level yarn splitting structure 355 in the fiber travel direction. The first-level yarn splitting structure 351 is a single-layer structure, the second-level yarn splitting structure 352 is a two-layer structure, the third-level yarn splitting structure 353 is a three-layer structure, the fourth-level yarn splitting structure 354 is a four-layer structure, and the fifth-level yarn splitting structure 355 is a five-layer structure. The width of the yarn splitting structure decreases gradually in the travel direction. The five-level yarn splitting structures work together to optimize the thickness and number of layers of the fiber yarn step by step. The decreasing width ensures that while the number of fiber yarn layers increases, the resin coating thickness also increases simultaneously. This allows for the simultaneous layering and impregnation of resins with different properties, thereby improving the overall performance of the thermoplastic fiber tape with different structural layers in terms of material properties and layer strength.

[0053] like Figure 2As shown, the traction conveying module 4 includes a central main roller 41, an impregnation cavity 43 forming around the main roller 41, and several distribution rollers 42 disposed within the impregnation cavity 43 and evenly distributed around the main roller 41. A gap adjustment structure 44 is provided between the main roller 41 and the distribution rollers 42. Support structures 45 are also provided on both sides and bottom of the main roller 41. The module also includes a circumferential heating structure 46, an active traction impregnation drive device 47, multiple driven traction impregnation drive devices 48, and an impregnation product outlet 49. Both the main roller 41 and the distribution rollers 42 are shaft structures with elastic coverings. Typically, the elastic coverings are high-temperature resistant polytetrafluoroethylene composite materials. The active traction impregnation drive device 47 drives the main roller 41, and the multiple driven traction impregnation drive devices 48 drive the distribution rollers 42 in a coordinated operation. Simultaneously, the main roller 41 and the distribution rollers 42 are adjusted synchronously by a PLC intelligent monitoring and control system. The aforementioned active traction impregnation drive device 47 and multiple driven traction impregnation drive devices 48 are all servo motors or ordinary drive motors equipped with speed change modules. The continuous fiber resin composite material output from the impregnation module 2 is continuously impregnated and conveyed under the traction of the main roller 41 and the evenly distributed distribution rollers 42. Simultaneously, the thickness of the continuous fiber strip is flexibly adjusted using the gap adjustment structure 44. The circumferential heating structure 46, under the control of the PLC module, provides heating during the continuous fiber conveying process, with a temperature control range of 200-300℃. The gap adjustment structure 44 between the main roller 41 and the distribution rollers 42 has an adjustment range of 0-6mm and is used for traction, impregnation, and compaction of the composite material strip from the fiber thickening layup module 3. The circumferential heating structure 46 is located within the cavity structure between the support mechanisms on both sides of the main roller 41 and is symmetrically fixed to the support mechanisms 45 on both sides, providing heating for the traction conveying module 4.

[0054] like Figure 2 As shown, an impregnation outlet 49 is provided at the bottom of the impregnation chamber 43, and the fixed-length cutting module 5 is located inside the impregnation outlet 49. It includes a front-end fixed-length cutting roller 51, a driven cutting roller 52, a fixed-length cutting power adjustment device 53, and a vision inspection device 54. Continuous fiber resin composite material enters the fixed-length cutting module 5 through the impregnation outlet 49 in the traction conveying module 4. The fixed-length cutting roller 51, together with the fixed-length cutting power adjustment device 53 and the driven cutting roller 52, cuts the continuous fiber into fixed-length fibers of 16-20mm. Simultaneously, the vision inspection device 54 performs real-time detection of the fiber length and surface flatness after fixed-length cutting, automatically stopping and adjusting if abnormalities occur. The fixed-length cutting roller 51 is coated with diamond; the fixed-length power adjustment device 53 uses a servo-synchronous electric device and an external gear structure to synchronously control the fixed-length cutting roller 51 and the driven cutting roller. The cutting length is adjusted online by the rotation speed, with a control range of 16-20mm.

[0055] like Figure 6 As shown, the mixing conveying module 6 includes a distributed screw conveying structure 61, a mixing conveying drive device 62, and an outer circumferential temperature regulating device 63. The distributed screw conveying structure 61 consists of screws, with the thread spacing on the screws forming the fiber composite material flow cavity. The thermoplastic continuous fiber composite material is cut into 16-20mm long fibers by the fixed-length cutting module 5 and conveyed to the inlet of the mixing conveying module 6. The screws in the distributed screw conveying structure are of equal depth, with the pitch decreasing progressively along the conveying direction. Continuous scraper grooves 64 are provided at the top of the screw edges, enabling secondary auxiliary stirring. This mixing conveying module 6 operates primarily as a conveying and distributing mixing unit, with weakened shearing action. It is used to melt, finally impregnate, and convey the equal-length and equal-width long fiber composite material cut by the fixed-length cutting structure 51.

[0056] Example 2: An operation method for a multi-stage dip molding equipment, comprising the following steps:

[0057] Step 1: 1200tex glass fiber yarn is selected. The preheating and dehumidification module 1 uses far-infrared heating component 13 to provide preheating and dehumidification for the fiber yarn, and the temperature is set to 100℃. The PLC control module 8 provides real-time feedback to ensure that the moisture content of the fiber yarn after passing through is ≤0.5%. The impregnation module 2 has a first injection structure 211 on the side of the inlet end to inject thermoplastic resin. The thermoplastic resin is polypropylene (PP). The high gradient temperature zone adjustment mechanism 23 is set to 200℃ (PP melting temperature +5℃) to initially impregnate the 1200tex glass fiber yarn and obtain the initial impregnated material.

[0058] Step 2: The temperature of the low gradient temperature zone regulating mechanism 24 is set to 120℃ (PP gel temperature). The initial impregnated material enters the low gradient temperature zone regulating mechanism 24 and is converted and cooled to the high elastic state of the resin matrix.

[0059] Step 3: The impregnated material, after being adjusted to a low gradient temperature zone, enters the fiber thickening layup module 3. The fiber thickening layup module 3 is equipped with a 5-stage yarn-separating thickening structure 35, namely, a first-stage yarn-separating structure 351, a second-stage yarn-separating structure 352, a third-stage yarn-separating structure 353, a fourth-stage yarn-separating structure 354, and a fifth-stage yarn-separating structure 355. The first-stage yarn-separating structure 351 has a thickness of 1 mm and a width of 800 mm; the second-stage yarn-separating structure 352 has a thickness of 1.5 mm and a width of 600 mm; the third-stage yarn-separating structure 353 has a thickness of 2 mm and a width of 400 mm; the fourth-stage... The yarn splitting structure 354 has a thickness of 2.5mm and a width of 200mm, while the fifth-level yarn splitting structure 355 has a thickness of 3mm and a width of 100mm. The five-level yarn splitting structures work together to optimize the thickness and number of layers of fiber yarn step by step, with the width decreasing in a stepwise manner and the thickness increasing in a stepwise manner. The fiber thickening and layering module 3 has two sets of resin injection ports on its side, namely the second injection structure 33 and the third injection structure 34, which inject flame-retardant PP and toughened PP respectively. This allows for the simultaneous layering and impregnation of resins with different properties, thereby improving the overall performance of the thermoplastic fiber tape with different structural layers in terms of material properties and layer strength.

[0060] Step 4: The rotation speed of the intermediate main roller 41 of the traction conveying module 4 is set to 1 m / min. The surrounding distribution rollers 42 are adjusted by the gap adjustment structure 44, with an adjustment range of 26 mm. The active traction impregnation drive device 47 drives the intermediate main roller 41, and the driven traction impregnation drive device 48 drives the distribution rollers 42 to run synchronously. The impregnated material is pulled and compacted by the traction conveying module 4 and then discharged through the impregnated product outlet 49. The fixed-length cutting module 5 is set in the impregnated product outlet 49. The fixed-length cutting roller 51 and the driven cutting roller 52 in the fixed-length cutting module 5 are driven by the fixed-length cutting power adjustment device 53, and their rotation speed is adjusted synchronously with the traction speed. The vision inspection device 54 performs real-time detection on the fiber length and surface flatness after fixed-length cutting. When there is an abnormality, the signal is fed back to the PLC intelligent detection control module 8 and the machine is automatically stopped for adjustment. The continuous strip material with improved product qualification rate is cut into long fiber segments with a length range of 16-20 mm.

[0061] Step 5: The rotational speed of the screw in the distributed screw combination conveying structure 61 of the mixing conveying module 6 is dynamically adjusted according to the product production requirements. The screw pitch gradually decreases from 80mm to 40mm. The long fiber segment enters the mixing conveying module. The top of the screw rib is provided with a continuous scraper groove 64. While the screw is rotating, secondary auxiliary stirring is achieved through the scraper groove 64. Under the stirring and conveying action of the screw, the material is melted, finally impregnated and conveyed to the molding and shaping module to be pressed into a product.

[0062] The temperature of the molding and shaping module 7 is set to no less than 180°C, and the fully impregnated composite material melt is transferred to the molding and shaping module 7 to be pressed into a product.

Claims

1. A multi-stage impregnation molding equipment, characterized in that: It includes a preheating and dehumidification module, an impregnation module, a fiber thickening and layup module, a traction conveying module, a fixed-length cutting module, and a mixing conveying module. It also includes a molding and shaping module, a PLC control module, and a support structure. The PLC control module realizes the linkage control of temperature, pressure, traction speed, and cutting length in each area. The preheating and dehumidification module includes a preheating channel and a heating chamber. The heating chamber is equipped with a far-infrared heating component and a humidity detection module. The preheating channel runs through the heating chamber, and its top is a split-type visual observation module. The impregnation module includes a resin phase change adjustment zone on the front, a filling module on the side, and several temperature zone adjustment mechanisms arranged at the front and rear. A heat insulation device is arranged between the several temperature zone adjustment mechanism zones, and a heating device is arranged inside the temperature zone adjustment mechanism. The fiber thickening layup module includes an upper layup module and a lower layup module. Multiple injection structures are provided on the side of the fiber thickening layup module. A yarn splitting thickening structure and a fiber thickening layup flow channel are provided between the upper layup module and the lower layup module. Several levels of yarn splitting structures are provided in the fiber thickening layup flow channel along the direction of travel. The number of yarn splitting layers in each level of the yarn splitting structure increases progressively along the fiber travel direction, while the width decreases progressively. The traction conveying module includes a central main roller, an impregnation cavity surrounding the main roller, and several distribution rollers arranged around the main roller within the impregnation cavity. A gap adjustment structure is provided between the corresponding distribution rollers to adjust the gap between the distribution rollers and the main roller. The traction conveying module also includes support structures on both sides and at the bottom. An impregnation outlet is provided at the bottom of the impregnation cavity. Several circumferential heating devices are provided inside the main roller. An active traction impregnation drive device is connected to the main roller, and a driven traction impregnation drive device is connected to the distribution rollers.

2. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The fixed-length cutting module is installed inside the outlet of the impregnated product. The fixed-length cutting module includes a fixed-length cutting roller at the front end and a driven cutting roller. The fixed-length cutting roller is connected to the fixed-length cutting power adjustment device, and a visual inspection device is installed at the cutting and dropping point.

3. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The hybrid conveying module includes a distributed screw combined conveying structure, a hybrid conveying drive device, and an outer circumferential temperature regulating device, wherein the distributed screw combined conveying structure includes a fiber composite material flow cavity and a screw.

4. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The high gradient temperature zone adjustment mechanism in the impregnation module has a temperature adjustment range of 200-300℃. The temperature adjustment is achieved through a combination of the high gradient temperature zone heating device and the PLC control module.

5. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The fiber thickening layup module has a rectangular structure, with a second injection structure for resin injection on the side of the inlet end and a third injection structure for resin injection on the side of the outlet end. The injection ports of both the second and third injection structures have equal diameter and continuous cross-sections. The high-elasticity composite material formed by the low gradient temperature zone adjustment mechanism is used to seal the resin injected by the second injection structure. The yarn thickening structure uses a three-dimensional weaving method to form a three-dimensional interwoven structure of fibers in the longitudinal space, realizing the gradient layup preforming of the fiber-resin composite material in the fiber thickening layup channel.

6. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The gap between the main roller and the distribution roller is adjustable from 0 to 6 mm. The main roller and the distribution roller are used to pull, impregnate and compact the composite strip from the fiber thickening layup module. The circumferential heating structure is located around the main roller and fixed to the support mechanism on both sides.

7. The multi-stage impregnation molding equipment according to claim 3, characterized in that: The screw in the distributed screw combined conveying structure is a constant depth screw with the pitch decreasing gradually along the conveying direction, and the top of its screw edge is provided with a continuous scraping groove.

8. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The fixed-length cutting roller is coated with diamond; the fixed-length power adjustment device is a servo-synchronous electric device and uses an external gear structure to synchronously control the fixed-length cutting roller and the driven cutting roller. The cutting length is adjusted online by the rotation speed, and the control range is 16-20mm.

9. The multi-stage impregnation molding equipment according to claim 1, characterized in that: The main roller and the distribution roller are shaft structures with an elastic covering, which is a high-temperature resistant polytetrafluoroethylene composite material.

10. A method for operating a multi-stage dip molding equipment, wherein the multi-stage dip molding equipment as described in claim 5 is characterized in that: The above includes the following steps: Step 1: After the continuous fiber yarn bundle is preheated and dehumidified, it enters the high gradient temperature zone adjustment mechanism and is initially impregnated with the first type of resin melt injected by the first injection structure to obtain the preliminary impregnated material; Step 2: The initially impregnated material enters the low-gradient temperature zone regulating mechanism and is converted and cooled to the high-elasticity state of the resin matrix; Step 3: Within the fiber thickening layup module, the thickness of the fiber resin composite material is longitudinally increased within a single bundle of fibers in the fiber resin composite tape by mechanical means. At the same time, a second resin and a third resin can be selectively injected through the second injection structure and the third injection structure. Step 4: The continuous strip, after being pulled, impregnated, and compacted by the traction conveyor module, is cut into long fiber segments with a length range of 16-20mm. Step 5: The long fiber segments enter the mixing and conveying module, where they are melted, impregnated, and finally conveyed to the molding and shaping module to be pressed into products under the action of stirring and conveying.

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