A multi-component automatic proportioning blending forming system and method of a bio-based composite material

Abstract

The application discloses a multi-component automatic proportioning blending forming system and method of a bio-based composite material. The system collects the rotating speed, torque and pressure and other parameters of each section of a screw rod through a multi-component automatic proportioning system, establishes a material filling state model in combination with the geometric structure of the screw rod, decouples the torque into the distribution of combined shearing action along the axial direction and the radial direction, constructs and dynamically corrects the shearing path experienced by the bio-based fiber according to the pressure jump of the material flow direction and the section junction, simulates the progressive fracture process of the bio-based fiber under the synergistic action of axial stretching and radial bending along the shearing path, accurately obtains the cumulative evolution result of the fiber length, and determines the fiber segmented state of each screw rod section. According to the fiber segmented state, the rotating speed of the screw rod and the position of the multiple axial feeding ports are synergistically adjusted and iteratively optimized, effectively solving the process difficulty that the bio-based fiber is easily broken during blending, and improving the mechanical properties and processing stability of the final composite material.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing and plastic recycling technology, specifically to a multi-component automatic proportioning and blending molding system and method for bio-based composite materials. Background Technology

[0002] With the continuous increase in the use of plastic products, the recycling of waste plastics has become an important research direction in the field of materials engineering. Recycled plastics, due to their wide availability and low cost, are widely used in the preparation of composite materials. To improve the mechanical properties of recycled plastics, bio-based fiber materials are often introduced as reinforcing components, forming composite material structures through blending extrusion. In existing technologies, the preparation of multi-component composite materials is usually completed using screw extrusion equipment, with automatic proportioning of each component achieved through a metering and feeding unit. Simultaneously, material properties are controlled by adjusting process parameters such as screw speed and temperature. This type of technical solution generally belongs to the field of plastic blending technology, and its core lies in controlling the mixing effect through macroscopic process parameter adjustment.

[0003] However, the blending behavior of recycled plastics and bio-based fibers in actual processing is significantly complex. On the one hand, the molecular chains of recycled plastics degrade after multiple thermal processing, altering their flowability and viscoelastic properties, making it difficult to stably control the flow state during processing. On the other hand, bio-based fibers are subjected to shearing forces during screw extrusion, resulting in breakage and continuous changes in their length distribution throughout the process. Existing technologies typically adjust these parameters based solely on mass ratios or overall process parameters, neglecting the local stress states and transmission relationships experienced by bio-based fibers in different sections of the screw. This leads to significant differences in fiber length distribution under the same ratios but different processing paths.

[0004] Furthermore, there is an inherent contradiction between the dispersion and length retention of bio-based fibers: increasing shear strength promotes dispersion of bio-based fibers in the matrix, but simultaneously exacerbates fiber breakage; decreasing shear strength helps maintain fiber length, but reduces dispersion uniformity. Existing technologies typically employ a compromise approach through single parameter adjustment, lacking differentiated control methods for different processing stages.

[0005] Further analysis reveals that the fracture behavior of bio-based fibers is not only related to local shear strength but also closely related to the actual transport path of the bio-based fibers in the screw. Due to the characteristics of material flow in the screw, such as hysteresis, backflow, and local compression, the residence time and action sequence of different components vary in different sections, resulting in a significant path-dependent characteristic of the shearing action experienced by the bio-based fibers.

[0006] Furthermore, existing technologies typically treat the screw extrusion process as a uniformly transmitted process along the axial direction, without modeling the spatial distribution of the composite shear force and its transmission relationship between segments. They also fail to consider the additional effects of pressure changes at segment connections on bio-based fibers. Consequently, it is difficult to accurately describe the force path and fracture process of bio-based fibers during processing. In actual production, the location where bio-based fibers are added is usually fixed, and the impact of the processing path on the fracture process of bio-based fibers is not adjusted. This makes it impossible to optimize the shear path experienced by bio-based fibers after entering the system, further exacerbating the uncertainty of fiber length distribution.

[0007] In view of this, the present invention provides a multi-component automated proportioning and blending molding system and method for bio-based composite materials, thereby solving the above-mentioned problems. Summary of the Invention

[0008] The purpose of this invention is to provide an automated multi-component blending and molding system and method for bio-based composite materials, which solves the problem that the composite shear path experienced by bio-based fibers during multi-component blending and extrusion cannot be characterized and controlled, resulting in uncontrollable fiber length evolution.

[0009] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an automated multi-component blending and molding method for bio-based composite materials, comprising the following steps: Based on a multi-component automatic proportioning system, recycled plastics and bio-based fibers are added to a screw extrusion unit, and the rotational speed, torque, melt pressure and material temperature of each screw section are collected during the material conveying process. Combining the screw lead and screw clearance, the torque and melt pressure are correlated to establish the material filling state in each screw section, and the torque is decomposed into a composite shearing action distribution along the screw axial and radial directions based on the material filling state. Based on the sequential relationship of material conveying in each screw section, the distribution of composite shearing action is correlated according to the material flow direction to form the shearing path experienced by bio-based fibers, and additional shearing action on bio-based fibers is introduced at the connection of adjacent sections due to changes in melt pressure; the range of action of each section in the shearing path is modified according to the residence distribution of different components in the screw, so that the shearing path changes with the material conveying process. Along the shear path, the bio-based fiber is subjected to a fracture action segment by segment according to the distribution of composite shear action in each segment, and the fiber length after the previous segment fracture participates in the fracture process of the next segment to obtain the fiber length change result; the fiber segmentation state of each screw segment is determined according to the fiber length change result and the mixed action relationship of the corresponding segment. Based on the fiber segmentation state of each screw section, the rotation speed and the addition position of the bio-based fiber in the corresponding section are adjusted in a coordinated manner. The addition position is selected from multiple feeding ports distributed along the screw axis. Based on the adjusted rotation speed and feeding port, the shearing path is reconstructed and the fiber length change process is repeated. When the fiber length change result is in a stable range, the corresponding rotation speed and feeding port are locked.

[0010] As a preferred embodiment of the first aspect of the present invention, the method of decomposing the torque into a composite shear force distribution along the screw axial and radial directions based on the material filling state includes the following steps: Obtain the helical propulsion space parameters corresponding to the screw lead and the radial constraint space parameters corresponding to the screw clearance, construct the spatial occupancy profile of the material in the screw section, and map the real-time collected melt pressure distribution to the spatial occupancy profile; Based on the distribution ratio of the material in the axial propulsion vector and the radial spreading vector in the space-occupying contour, the total torque is decoupled into a first component acting on the axial propulsion region and a second component acting on the radial constraint region within the same segment. Combining the screw rotational angular velocity, the first component is converted into a first shear force transmitted along the screw axis, and the second component is converted into a second shear force transmitted along the screw radially. The first shear force and the second shear force are vector-synthesized to obtain the composite shear force distribution corresponding to each screw segment, which serves as the input parameter for constructing the shear path.

[0011] As a preferred embodiment of the first aspect of the present invention, the process of constructing the spatial occupancy contour includes: The axial compression ratio of the material is determined based on the melt pressure gradient between adjacent screw sections, thus defining the axial occupancy range of the material within the section. Based on the axial occupancy range, and combined with the geometric radial boundary of the screw thread gap, the expansion limit of the material in the radial direction is calculated to form the radial occupancy range; By integrating the axial and radial occupancy regions, a three-dimensional spatial occupancy profile of the material within the screw channel is generated. The three-dimensional spatial occupancy contour is coupled and matched with the melt pressure field to output a dynamic filling state model for torque decomposition.

[0012] As a preferred embodiment of the first aspect of the present invention, the modification of the effective range of each segment in the shearing path includes the following steps: Identify the feeding sequence and feed port coordinates of recycled plastics and bio-based fibers in each screw section, and determine the initial distribution phase of each component in the screw axis; Based on the initial distribution phase and material flow rate, the dynamic residence time of each component in each screw section and the actual covered section range are calculated in real time. Monitor the melt pressure change vector at the junction of adjacent screw sections to determine the axial overflow or backflow offset of the material at the junction, and define the physical extension area of ​​shear action to adjacent sections accordingly. The actual covered segment range and the physical extension area are superimposed to update the effective boundary of the shear path.

[0013] As a preferred embodiment of the first aspect of the present invention, the process of determining the shear action propagation region based on the direction of melt pressure change includes: Fit the axial pressure gradient curve at the junction of adjacent screw sections and extract the transmission vector of pressure fluctuation; Based on the transfer vector, determine the advance or lag distance of the material flow at the section junction and identify the deviation parameters of the motion path; The effective points of the combined shear force distributed in the spatially occupied contour are extended along the direction deviating from the parameter to generate the shear force field extension region; The generated extended region is incorporated into the current shear path model as a modified boundary condition for the simulation of bio-based fiber fracture.

[0014] As a preferred embodiment of the first aspect of the present invention, obtaining the fiber length change result includes the following steps: According to the physical arrangement order of each screw segment in the shear path, extract the force vector of the composite shear action distribution corresponding to each segment and its three-dimensional coordinate action position in the spatial contour. Within each screw section, the composite shear force distribution vector is mapped to the real-time distribution area of ​​the bio-based fiber in the spatial contour, and the axial tensile stress and radial bending moment borne by the bio-based fiber within the screw section are calculated. The fiber length state after the current screw section is processed is used as the iterative input condition for the next screw section, and the composite shearing action distribution is accumulated in subsequent sections to form a cumulative fracture process that is transmitted segment by segment during the material conveying process. Traverse all screw segments involved in the shearing path and output the final length distribution data of the bio-based fiber as a quantitative basis for determining the fiber segmentation state.

[0015] As a preferred embodiment of the first aspect of the present invention, the process of forming the fiber segmentation state includes the following steps: Identify the physical contact points between the composite shear force distribution and the bio-based fiber in the spatial occupancy profile, and mark the relative displacement of the contact points with respect to the centroid of the bio-based fiber. Based on the gradient distribution of axial tensile stress in the axial direction of bio-based fibers, the vulnerable tensile regions of bio-based fibers are determined. Based on the curvature distribution of the radial bending moment in the spatially occupied profile, the spatial critical region for nonlinear bending deformation of bio-based fibers is determined. When the tensile region and the spatial critical region spatially overlap at the same coordinate on the bio-based fiber and the stress value exceeds the preset fracture threshold, a fracture node is generated at that location, and the bio-based fiber is discretized and segmented to update the fiber segmentation status of the current segment.

[0016] As a preferred embodiment of the first aspect of the present invention, the coordinated adjustment of the rotation speed and the position of the bio-based fiber addition includes the following steps: Based on the fiber segmentation state of each screw section, the shear energy consumption demand distribution required by each section to maintain the target fiber length is calculated and mapped to the screw axial coordinate system; Adjust the drive speed of each screw section according to the demand distribution to match the real-time composite shear force distribution with the shear energy consumption demand distribution; Retrieve the position coordinates of multiple preset feeding ports along the screw axis, and determine the sequence of shear path segments covered by each feeding port to the screw discharge end; Establish a correlation matrix between the shearing path segment sequence and the fiber length evolution result, and select the feed port from multiple feed ports that makes the fiber segmentation state meet the preset target.

[0017] As a preferred embodiment of the first aspect of the present invention, the process of selecting the feeding port includes the following steps: For each alternative feeding port, extract the composite shear force distribution characteristics and material residence time distribution of each segment within the sequence. The fiber length change after entering each feeding port was simulated and pre-calculated using the fracture transmission mechanism of bio-based fibers to obtain the statistical distribution of fiber length at different feeding positions. By performing a matching degree analysis between the pre-calculation results and the target fiber length range, a set of candidate feeding ports that meet the mechanical performance requirements is identified. In the set of candidate feeding ports, the feeding port with the shortest corresponding shearing path length or the fewest shearing peak segments is selected as the final feeding position, and the switching command of the actuator is executed to update the physical shearing path.

[0018] In a second aspect, the present invention provides a multi-component automatic proportioning and blending molding system for bio-based composite materials, used to perform the first aspect, including a multi-component automatic proportioning module, a screw extrusion module, a parameter acquisition module, a shear action construction module, a shear path construction module, a fiber fracture calculation module, and a collaborative control module; The multi-component automatic proportioning module is connected to the screw extrusion module and is used to add recycled plastic and bio-based fiber into the screw extrusion module through different feeding ports. The parameter acquisition module is set at the position of each screw section corresponding to the screw extrusion module, and is used to collect the rotation speed, torque, melt pressure and material temperature of each screw section, and establish a corresponding relationship according to the axial position of the screw; The shearing action construction module is connected to the parameter acquisition module. It is used to correlate the torque and melt pressure by combining the screw lead and screw clearance, establish the material filling state of each screw section, and decompose the torque into a composite shearing action distribution along the screw axis and radial direction. The shear path construction module is connected to the shear action construction module. It is used to associate the composite shear action distribution according to the material flow direction based on the material conveying relationship in each screw section, forming a shear path experienced by the bio-based fiber. It also introduces melt pressure changes at the connection of adjacent sections to form a pre-shear action, and corrects the range of action of the shear path according to the residence distribution of different components in the screw. The fiber breakage calculation module is connected to the shear path construction module. It is used to apply a compound shearing action to the bio-based fiber segment by segment along the shear path, and use the fiber length state of the previous screw segment as the input condition for the next screw segment to obtain the fiber length change result. Based on the fiber length change result, the fiber segmentation state of each screw segment is determined. The collaborative control module is connected to the fiber breakage calculation module and the screw extrusion module. It is used to adjust the rotation speed of the corresponding section according to the fiber segmentation state of each screw section, select the addition position of bio-based fiber from multiple feeding ports distributed along the screw axis, update the shear path based on the adjusted rotation speed and feeding port position, and lock the corresponding rotation speed and feeding port when the fiber length change result is in a stable range.

[0019] The technical effects and advantages provided by the present invention in the above technical solution are as follows: This invention establishes a correspondence between the material filling state and the distribution of composite shear forces during screw extrusion, and establishes a shear path reflecting the actual material conveying trajectory based on this composite shear force distribution, thus continuously expressing the stress sequence experienced by bio-based fibers in each screw section. Furthermore, by performing segment-by-segment fracture calculations on the bio-based fibers along the shear path and transmitting the fracture results between segments, the fiber length change process becomes calculable. Based on this, the screw speed and feed port position are coordinated and adjusted according to the fiber segmentation state, altering the distribution of composite shear forces along the path, thereby reverse-regulating the bio-based fiber fracture process. This gradually stabilizes the fiber length change, reducing fluctuations during processing and improving the consistency of the composite material's mechanical properties. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a flowchart of the multi-component automatic proportioning and blending molding method for bio-based composite materials of the present invention; Figure 2 This is a structural diagram of the multi-component automatic proportioning and blending molding system for bio-based composite materials of the present invention. Detailed Implementation

[0022] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0023] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details are provided in the following description to give a full understanding of exemplary embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more specific details omitted, or other methods, components, steps, etc., can be employed. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0024] Example 1 like Figure 1 As shown, this embodiment provides a multi-component automated proportioning and blending molding method for bio-based composite materials, including the following steps: Based on a multi-component automatic proportioning system, recycled plastics and bio-based fibers are added to a screw extrusion unit, and the rotational speed, torque, melt pressure and material temperature of each screw section are collected during the material conveying process. Combining the screw lead and screw clearance, the torque and melt pressure are correlated to establish the material filling state in each screw section, and the torque is decomposed into a composite shearing action distribution along the screw axial and radial directions based on the material filling state. It should be noted that the multi-component automatic proportioning system is implemented by combining the metering and feeding unit of the existing screw extrusion device with the main control system. Recycled plastics and bio-based fibers are added to different feed ports of the screw extrusion device through independent metering and feeding units. Each metering and feeding unit continuously supplies materials at a set mass ratio through a mass flow controller. The screw extrusion device includes multiple screw sections arranged sequentially along the axial direction. Each screw section has a corresponding screw lead and screw clearance. During the material conveying process, the screw structural parameters are acquired by sensing components set on the outside of each screw section. The screw structural parameters include rotational speed, torque, melt pressure, and material temperature. Specifically: the rotational speed is directly output by the drive motor encoder; the torque is obtained by converting the motor load signal; the melt pressure is collected by pressure sensors set on the barrel wall of each section; and the material temperature is obtained by embedded thermocouples. The above parameters are synchronously collected according to the axial position of the screw and matched one by one with the corresponding sections.

[0025] The material filling state refers to the combined state of the space occupied and pressure distribution of the material within the screw channel during screw extrusion, influenced by the geometric constraints formed by the screw lead and screw clearance, as well as the melt pressure. For any screw section, the theoretical propulsion distance of the material in the axial direction within a unit rotation cycle is determined based on the screw lead of the current screw section to obtain the basic conveying capacity of the material in the axial direction. Then, based on the screw clearance of the screw section, the expandable space range of the material in the radial direction is determined to obtain the radial constraint boundary of the material in the channel. Based on the melt pressure change between the inlet and outlet of the screw section, the compression or release state of the material within the screw section is determined, and the actual occupancy range of the material in the axial direction is corrected accordingly. The corrected axial occupancy range is spatially combined with the radial space range to obtain the spatial occupancy structure of the material within the screw section. The spatial occupancy structure is associated with the melt pressure distribution of the corresponding section, so that each spatial position corresponds to its pressure state, thereby forming the material filling state.

[0026] It should be noted that since the effect of torque in the screw section depends on the spatial distribution of the material and the pressure conditions, if only the overall torque is considered, it is impossible to distinguish the action modes corresponding to different spatial positions. By constructing the material filling state, a correspondence can be established between the torque and the actual distribution of the material in space, so that the torque can be distributed in different spatial regions, thereby achieving axial and radial decomposition. The distribution of composite shear action can correspond to the actual location of the material, so that the subsequent fiber stress analysis has a clear physical basis.

[0027] Furthermore, the material filling state not only describes the spatial position of the material in the screw channel, but also the pressure condition corresponding to that position, so that the torque action can establish a correspondence with the spatial distribution of the material. The step of decomposing the torque into a composite shear action distribution along the screw axial and radial directions based on the material filling state includes the following steps: Obtain the helical propulsion space parameters corresponding to the screw lead and the radial constraint space parameters corresponding to the screw clearance, construct the spatial occupancy profile of the material in the screw section, and map the real-time collected melt pressure distribution to the spatial occupancy profile; It should be noted that the spatial occupancy profile is used to describe the instantaneous three-dimensional occupancy boundary of the material within the screw channel. This instantaneous three-dimensional occupancy boundary is formed by the geometric range defined by the screw lead and screw clearance, as well as the effect of melt pressure, and changes during the material conveying process. The material filling shape formed by the combined effect of the spatial boundary defined by the screw lead and screw clearance, and the distribution of melt pressure in the channel, transforms the originally difficult-to-observe material distribution state into a calculable spatial model by introducing the spatial occupancy profile.

[0028] To further explain, the process of constructing the spatial occupancy contour includes: The axial compression ratio of the material is determined based on the melt pressure gradient between adjacent screw sections, defining the axial occupied range of the material within each section. By comparing the melt pressure changes between adjacent screw sections, the compression effect experienced by the material upon entering the current section can be obtained. When the inlet pressure is higher than the outlet pressure, the material is in a released state within the screw section; when the inlet pressure is lower than the outlet pressure, the material is in a compressed state within the screw section. Based on the compressed state, the axial occupied length of the material within the screw section can be determined, i.e., the actual range covered by the material in the axial direction of the screw.

[0029] The radial distribution of material is geometrically restricted by the screw gap. When the material is in a compressed state, it will expand into the screw gap region in the radial direction; when the material is in a released state, it tends to shrink back in the radial direction. By combining the axial occupied area with the geometric boundary of the screw gap, the actual spreading range of the material in the radial direction can be determined and the radial occupied area can be formed.

[0030] By spatially combining the axial and radial occupancy regions, a three-dimensional occupancy pattern of the material within the screw channel can be obtained. This pattern can be constructed by discretizing multiple sections along the screw axis and marking the radial occupancy range on each section, thereby forming a complete spatial occupancy profile.

[0031] The spatial occupancy profile is matched with the melt pressure distribution of the corresponding section, that is, the pressure value is mapped to each position point of the spatial occupancy profile, so as to obtain a filling state model reflecting the material under pressure at different positions; this model is used to describe the filling distribution of the material in the screw section and serves as the input condition for subsequent torque decomposition.

[0032] Based on the distribution ratio of the material in the axial propulsion vector and the radial spreading vector in the space-occupying contour, the total torque is decoupled into a first component acting on the axial propulsion region and a second component acting on the radial constraint region within the same segment. It should be noted that during screw extrusion, the driving torque is not uniformly distributed within the material. Instead, it is constrained by the screw lead and screw clearance structure, resulting in different effects in the axial propulsion region and the radial constraint region. The total torque can be divided into a first component along the screw axial direction and a second component along the screw radial direction within the spatial profile, where: The first component corresponds to the tensile force generated during the axial conveying of the material, and the second component corresponds to the extrusion force generated under radially confined conditions.

[0033] Combining the screw rotational angular velocity, the first component is converted into a first shear force transmitted along the screw axis, and the second component is converted into a second shear force transmitted along the screw radially. It should be noted that the screw's rotational angular velocity determines the relative motion speed of the material within its spatial contour. By correlating the torque component with the rotational angular velocity, the torque is transformed into a shearing force acting within the material. Combining the first component with the screw's rotational angular velocity yields the first shearing force transmitted along the screw's axial direction; combining the second component with the screw's rotational angular velocity yields the second shearing force transmitted along the screw's radial direction, thus establishing a correspondence between the shearing force and the material's distribution position within its spatial contour.

[0034] This can be understood as follows: the distribution of composite shear force is decomposed along the orientation direction of the bio-based fiber to obtain the force component along the length of the bio-based fiber, and its axial stress state is determined by combining the cross-sectional area of ​​the bio-based fiber; the shear force component perpendicular to the direction of the bio-based fiber is correlated with its position relative to the centroid of the bio-based fiber to obtain the bending state of the bio-based fiber at that position; the distribution of composite shear force is transformed into the stress form of the bio-based fiber in both axial and radial directions, so that the stress state of the bio-based fiber can establish a correspondence with its spatial position, that is: the first shear force corresponds to the tensile force of the bio-based fiber in the axial direction, and the second shear force corresponds to the bending force of the bio-based fiber in the radial direction; the first shear force and the second shear force correspond to the stress sources of the bio-based fiber in the axial tensile and radial bending processes, respectively; when the bio-based fiber is simultaneously in the tensile region and the bending region at the same position, the structural stability at that position decreases, a fracture node is generated at that position, and the bio-based fiber is segmented, thus forming a fiber length change process.

[0035] The first shear force and the second shear force are vector-synthesized to obtain the composite shear force distribution corresponding to each screw segment, which serves as the input parameter for constructing the shear path.

[0036] For example, the first shear force and the second shear force are superimposed according to their distribution positions in the spatial contour. That is, the axial and radial forces are recorded at each spatial position point to obtain the composite shear force distribution at that position. By summarizing the composite shear force distributions at each position point, the composite shear force distribution corresponding to the entire screw section can be obtained. This distribution serves as the basic input parameter for subsequent shear path construction.

[0037] Based on the material conveying sequence in each screw section, the distribution of composite shearing action is correlated according to the material flow direction to form the shearing path experienced by the bio-based fiber, and additional shearing action caused by melt pressure change is introduced at the connection position of adjacent screw sections; at the same time, the range of action of each section in the shearing path is modified according to the residence distribution of different components in the screw, so that the shearing path is updated with the material conveying process. It should be noted that the shear path is used to describe the distribution of compound shearing action and its spatial position that the bio-based fiber experiences sequentially along the material flow direction during screw extrusion. The shear path not only reflects the spatial arrangement of each screw section, but also reflects the transmission relationship of compound shearing action between sections and the energy transfer process in the material.

[0038] Specifically, during the material conveying process along the screw axis: the distribution of compound shearing action within the current section affects the initial stress state of the material when it enters the next screw section; by corresponding the action state of the previous screw section with the action input of the next screw section, the correlation between screw sections is established; the distribution of compound shearing action within each screw section is connected according to the material entry sequence, and the action output position of the previous screw section is matched with the action input position of the next screw section, thereby forming a shearing path structure with a continuous transmission relationship.

[0039] At the junction of adjacent screw sections, the melt pressure undergoes abrupt changes due to variations in screw geometry and screw clearance. This abrupt change has an additional effect before the material enters the next section. When the pressure increases axially, the material is compressed at this location, enhancing the contact between the bio-based fibers and the matrix, and the combined shear effect manifests as an additional loading effect. When the pressure decreases axially, the material relaxes at this location, and the local orientation of the bio-based fibers is adjusted, resulting in a redistribution of the stress state. Pressure changes alter the stress state of the bio-based fibers before they enter the next screw section, therefore, this effect needs to be introduced as an independent node into the shear path.

[0040] For example, by uniformly describing the distribution of composite shear action with the material flow process, the distribution of composite shear action in each segment is topologically associated according to the material entry sequence. This ensures that each shear action node contains not only the current segment information but also the action state of the source segment, thereby forming a shear path structure with a transmission relationship. The segment connection position is defined as the pre-shear action node, and the pressure change is mapped as an additional shear component. This additional shear component is inserted between the corresponding segments in the shear path, thereby forming a shear path structure that includes intra-segment action and inter-segment action, integrating the shear action originally dispersed in each segment into a continuous action structure.

[0041] Furthermore, the modification of the effective range of each segment in the shearing path includes the following steps: Different components enter the screw at different times and locations, so their initial distribution state needs to be marked in the shearing path. Based on the position coordinates of each feeding port and the corresponding feeding time sequence, the initial position distribution of recycled plastic and bio-based fiber in the screw axial direction is determined, and this distribution is defined as the initial distribution phase. This initial distribution phase is used to describe the starting position of different components in the screw.

[0042] The residence time of material in each screw section depends on the material flow velocity and the section length. When the flow velocity changes, the actual coverage area of ​​the material in the section also changes. Based on the material flow rate and screw speed, the axial propulsion distance of the material per unit time can be determined. Combined with the initial distribution phase, the entry time and exit time of each component in each section can be calculated, thereby obtaining the residence time of each component in the screw section and the actual coverage area.

[0043] At the boundary between adjacent sections, changes in melt pressure can cause overflow or backflow of material in the axial direction, thereby altering the original shearing path. When the direction of pressure change is consistent with the material conveying direction, the material will extend forward; when the direction of pressure change is opposite to the material conveying direction, the material will experience local backflow. By monitoring the changes in melt pressure at the boundary, the axial offset of the material at that location can be determined, and this offset can be used as the basis for the expansion of the shearing action into adjacent sections, thus obtaining the physical expansion area of ​​the shearing action.

[0044] The actual shear path should consider both the section coverage area and the pressure expansion area. By superimposing the actual coverage area of ​​each component in the screw section with the expansion area caused by pressure changes, the actual action boundary of the composite shear action distribution in each section can be obtained. The updated action boundary is then applied to the shear path to correct the original shear path, thereby obtaining a shear path that conforms to the actual processing state.

[0045] Furthermore, the process of determining the shearing action propagation region based on the direction of melt pressure change includes: Multiple pressure sampling points are extracted along the screw axis at the junction of adjacent sections, and a pressure change curve is constructed based on these sampling points. By analyzing the trend of the pressure change curve in the axial direction, the pressure transmission direction can be determined; that is, the pressure gradient curve along the axial direction at the junction of adjacent screw sections is fitted to extract the transmission vector of pressure fluctuation. Based on the pressure transmission direction, the direction of material movement offset at the interface can be determined, and the offset distance of the material in the axial direction can be determined. Then, based on the transmission vector, the flow advance or lag distance of the material at the section junction can be determined, and the deviation parameters of the movement path can be identified.

[0046] The effective points of the combined shear force distributed in the spatially occupied contour are extended along the direction deviating from the parameter to generate the shear force field extension region; The generated extended region is incorporated into the current shear path model, which describes the distribution of composite shear actions and the ordered structure of their spatial positions that bio-based fibers experience sequentially along the material flow direction during screw extrusion, serving as a modified boundary condition for simulating bio-based fiber fracture.

[0047] The shear path model is not a simple sequence of segments, but rather a correlation between the distribution of composite shear forces within each screw segment and the pressure changes between segments, providing a complete description of the force sequence and location experienced by the bio-based fiber during processing. Because the shear path model reflects the spatial distribution and transmission relationship of composite shear forces, it provides continuous input conditions for the fracture process of the bio-based fiber in each segment. Based on this, by applying the composite shear force distribution segment by segment according to the shear path, the fiber length change can be obtained, and the fiber segmentation state of each segment can be further determined. Adjusting the screw speed and feed port position according to the fiber segmentation state alters the distribution of composite shear forces along the path, thereby influencing the fracture process of the bio-based fiber. Through this process, the fiber length change can be regulated.

[0048] For example, a feeding port is taken as the starting position, and the section where the feeding port is located is taken as the starting point of the shearing path. As the screw rotates, the material enters the subsequent sections in sequence. In each section, there is a composite shearing action distribution obtained in step S101. The composite shearing action distributions of each section are connected in series according to the material entry order to obtain the initial shearing path. During the shearing path construction process, the output position of the composite shearing action distribution of the previous section is matched with the input position of the next section, so that the composite shearing action distribution is continuously transmitted along the material conveying direction. In this way, the shearing path forms a continuous structure containing "section action - transmission - section action". The section boundary is set as an independent action node in the shearing path, and the melt pressure change is mapped as an additional shearing component. The additional shearing component is inserted into the position between the corresponding sections in the shearing path, thereby forming an extended shearing path structure containing pre-shearing action.

[0049] Along the shear path, the bio-based fiber is subjected to a fracture action segment by segment according to the distribution of composite shear action in each segment, and the fiber length after the previous segment fracture participates in the fracture process of the next segment to obtain the fiber length change result; the fiber segmentation state of each screw segment is determined according to the fiber length change result and the mixed action relationship of the corresponding segment. It should be noted that, based on the shear path as input, the distribution of compound shear action is transformed into a calculable continuous action process according to the material flow sequence. During this process, segment-by-segment stress and fracture analysis is performed on the bio-based fibers. Since the bio-based fibers have already undergone deformation and length changes in the previous segment, the stress state in the subsequent segment is not the initial state, but a continuation of the previous state, thus forming a fracture process that is transmitted segment by segment along the shear path. The fracture process of the bio-based fibers depends on the transmission sequence of the compound shear action distribution in the shear path; that is, the structural state formed by the bio-based fibers in the previous segment directly affects its stress response in the subsequent segment. When the bio-based fibers enter a certain segment during screw extrusion, their length state already includes the influence of the compound shear action distribution in the previous segment. Therefore, the compound shear action distribution applied in the screw segment does not act on the initial bio-based fibers, but on the already deformed bio-based fiber structure. By using the fracture results of each segment as input conditions for subsequent segments, a fracture process that is transmitted segment by segment along the shear path can be formed, ensuring that the fiber length change is consistent with the actual processing process.

[0050] Furthermore, obtaining the fiber length change result includes the following steps: In the shear path, each screw segment corresponds to a composite shear action distribution node. According to the physical arrangement order of each screw segment in the shear path, the composite shear action distribution force vector corresponding to each segment and its three-dimensional coordinate action position in the spatial contour are extracted to obtain the complete action sequence. This can be understood as follows: to enable the distribution of composite shear action to participate in segment-by-segment fracture calculation, it needs to be transformed into a unified data structure. The following processing is performed on each screw segment in the shear path: the distribution of composite shear action within the screw segment's spatial occupancy contour is discretized, dividing the spatial occupancy contour into multiple positional units, each corresponding to a spatial coordinate; the composite shear action distribution vector is recorded at each positional unit, and a correspondence is established between this vector and the spatial coordinate of that positional unit; simultaneously, the distribution position and orientation direction of the bio-based fibers at that positional unit are read; the originally continuously distributed shear action is transformed into a set of discrete action units, each containing a correspondence of "spatial position—shear action—bio-based fiber orientation"; the action units in each screw segment are sorted according to the material flow direction and spliced ​​along the shear path, thus forming an action data chain covering the entire extrusion process.

[0051] Since bio-based fibers are dispersed in the spatial contour, it is necessary to map the distribution of composite shear forces to the region where the bio-based fibers are located. Within each screw segment, the position of the composite shear forces in the spatial contour is matched with the distribution area of ​​the bio-based fibers, so that the composite shear forces act on the location of the bio-based fibers. In this process, the distribution of composite shear forces can be decomposed into tensile forces along the fiber length direction and bending forces perpendicular to the direction of the bio-based fibers, thereby obtaining the stress state of the bio-based fibers in the screw segment. This can be understood as follows: in each action unit, the composite shear force distribution vector is projected onto the orientation direction of the bio-based fiber to obtain the action component along the fiber length direction, which is used to represent the tensile force of the bio-based fiber; at the same time, the component of the composite shear force distribution vector perpendicular to the orientation direction of the bio-based fiber is used as the source of the bending force; among them, the tensile force determines the tendency of the bio-based fiber to extend or break in the axial direction, and the bending force determines the deformation state of the bio-based fiber in the radial direction. In order to obtain the bending force intensity, it is necessary to combine the positional relationship of the action unit in the spatial contour to determine the distance of the position relative to the constraint position of the bio-based fiber, thereby obtaining the corresponding bending force effect.

[0052] For example, the stress state experienced by the bio-based fiber during screw extrusion originates from the composite shear distribution obtained in step S101 and is transmitted segment by segment through the shear path established in step S102. Therefore, it is necessary to quantitatively describe the stress state of the bio-based fiber in each action unit. The composite shear distribution is directional in space, and the bio-based fiber also has an orientation direction in its spatial outline. Therefore, it is necessary to decompose the composite shear distribution along the orientation direction of the bio-based fiber and its perpendicular direction to obtain different stress forms of the bio-based fiber.

[0053] For example, for any action unit, the distribution of its composite shear action is represented as a vector. The orientation of bio-based fibers is represented as a unit direction vector. ,in: This indicates the distribution of the combined shear force at this location, obtained by torque decomposition and spatial mapping, which includes information on direction and magnitude. This indicates the axial direction of the bio-based fiber at this location, and its value is 1, used only to indicate direction.

[0054] Based on this, the component of the composite shearing action distributed along the direction of the bio-based fiber is obtained by inner product calculation: ; in, This represents the component of the composite shear force distribution along the fiber length direction, which is used to characterize the tensile or compressive forces experienced by bio-based fibers in the axial direction.

[0055] Furthermore, to obtain the stress state of the bio-based fiber in this direction, this component is correlated with the cross-sectional area of ​​the bio-based fiber to obtain the axial tensile stress: ; in: This indicates the strength of the bio-based fiber along its length. It represents the equivalent cross-sectional area of ​​the bio-based fiber under stress, which is determined by the diameter of the bio-based fiber; it transforms spatial shearing into tensile force along the direction of the bio-based fiber, thereby reflecting whether the bio-based fiber is prone to axial fracture.

[0056] Meanwhile, to obtain the stress state of the bio-based fibers in the vertical direction, the component perpendicular to the bio-based fiber direction in the composite shear distribution is extracted, and it is expressed as: ; in, This represents the shear component perpendicular to the direction of the bio-based fiber, which is used to characterize the source of bending deformation of the bio-based fiber in space.

[0057] Furthermore, by combining this component with the spatial distance corresponding to the point of action, the bending force of the bio-based fiber at that location is obtained, which is expressed as: ; in: This indicates the bending strength experienced by the bio-based fiber at that location; This represents the distance of the functional unit relative to the bio-based fiber constraint position, which is determined by the geometric position in the spatially occupied profile.

[0058] It should be understood that the above calculation process is based on the decomposition of forces and the principle of force rectangularity, which divides the distribution of composite shear action into tensile action and bending action, thereby describing the stress state of bio-based fibers in the axial and radial directions respectively. In this way, the spatial shear action, which is originally difficult to directly characterize, is transformed into two independent action quantities that can be used for fracture determination, so that the fracture behavior of bio-based fibers can be described from the perspective of physical mechanism. In the subsequent fracture determination process, when bio-based fibers are subjected to strong axial tensile action and radial bending action at the same location, fracture is more likely to occur at that location, thereby realizing the determination of the fiber segmentation state.

[0059] Furthermore, the process of forming the fiber segmentation state includes the following steps: The composite shearing action is distributed in the spatial contour, while the bio-based fiber exists as a discrete entity in this space. Therefore, it is necessary to first determine the actual interaction position between the shearing action and the bio-based fiber. In the spatial contour, each discrete action unit has a corresponding spatial coordinate position, and the bio-based fiber can be represented as a spatial curve with a length direction in this region. Therefore, by determining the minimum distance relationship between the coordinates of the action unit and the spatial trajectory of the bio-based fiber, the physical contact point between the composite shearing action distribution and the bio-based fiber can be identified.

[0060] This can be understood as representing the bio-based fiber as a spatial line segment formed by connecting multiple discrete nodes. For each action unit location point, the minimum distance from it to each bio-based fiber node is calculated. When this distance is less than the preset contact judgment distance, the action unit is regarded as the contact point that interacts with the bio-based fiber. Taking the geometric center of the bio-based fiber as the centroid, the spatial distance vector from the contact point to the centroid of the bio-based fiber is calculated, thereby obtaining the relative displacement of the contact point relative to the centroid of the bio-based fiber, which is used for subsequent bending action calculation.

[0061] The fracture tendency of bio-based fibers in the axial direction is mainly determined by the distribution of axial tensile stress. The axial tensile stress at different locations along the fiber length varies, so it is necessary to determine the areas prone to fracture based on the stress variation along the fiber length.

[0062] This can be understood as discretizing the bio-based fiber into multiple computational units along its length, calculating the axial tensile stress value for each unit, and arranging these stress values ​​along the fiber length to obtain an axial stress distribution sequence. By comparing the stress changes between adjacent units, regions where the stress changes are more concentrated along the length are identified, and these regions are defined as tensile regions. These regions correspond to the stress concentration locations inside the bio-based fiber and are the main areas where tensile fracture occurs.

[0063] The bending deformation of bio-based fibers in space is determined by the radial bending moment. This bending behavior is closely related to the curvature change of bio-based fibers in space. When bio-based fibers are subjected to a strong radial force in a certain region, their spatial shape will bend, thus forming a local curvature change.

[0064] This can be understood as updating the spatial position of each discrete unit of the bio-based fiber based on the radial bending moment at each action unit, thereby obtaining the spatial morphology of the bio-based fiber in the screw section. By calculating the directional changes between adjacent discrete units, the curvature distribution of the bio-based fiber at each position is obtained. When the curvature change in a certain region is relatively concentrated, the region is defined as the bending critical region. This region represents the location where the bio-based fiber undergoes significant bending deformation and is an important region where structural instability occurs.

[0065] The fracture of bio-based fibers is not caused by a single factor, but by the combined effects of axial tension and radial bending. When a bio-based fiber is in both the tension region and the bending critical region at the same location, that location is subjected to both tension and bending, which reduces its structural stability and makes it more prone to fracture.

[0066] This can be understood as follows: In the discrete unit of bio-based fiber, it is determined whether each unit simultaneously satisfies the following conditions: located in the tension region and located in the bending critical region; when the above conditions are simultaneously satisfied, the unit position is marked as the fracture node, and the bio-based fiber is segmented at this position, dividing the original bio-based fiber into multiple sub-segments; the segmented bio-based fiber is reorganized into a new set of bio-based fibers, and the fiber segmentation state in the screw section is updated. This updated fiber segmentation state will be used as the input for subsequent screw section calculations, thereby realizing the segment-by-segment transmission of the fracture process.

[0067] The fiber length state after the current screw section is processed is used as the iterative input condition for the next screw section. The composite shearing action distribution is accumulated in the subsequent sections to form a cumulative fracture process that is transmitted segment by segment with the material conveying process. This makes the bio-based fiber form a continuous fracture process in the entire shearing path, so that the length change result is consistent with the material conveying process. Traverse all screw segments involved in the shearing path and output the final length distribution data of the bio-based fiber as a quantitative basis for determining the fiber segmentation state.

[0068] For example, the fiber segmentation state is used to describe the distribution and length characteristics of bio-based fibers in each screw section. The fiber length variation results are correlated with the mixing effect of each section: when the fiber length in a certain section remains relatively long, it indicates that the combined shearing effect distribution of the screw section has a weaker impact on the bio-based fibers; when the fiber length in a certain section is significantly shortened, it indicates that the combined shearing effect distribution of the screw section has a stronger impact on the bio-based fibers; thus, the fiber segmentation state of each screw section is determined and used as the basis for subsequent process parameter adjustments.

[0069] Based on the fiber segmentation state of each screw section, the rotation speed and the addition position of the bio-based fiber in the corresponding section are adjusted in a coordinated manner. The addition position is selected from multiple feeding ports distributed along the screw axis. Based on the adjusted rotation speed and feeding port, the shearing path is reconstructed and the fiber length change process is repeated. When the fiber length change result is in a stable range, the corresponding rotation speed and feeding port are locked.

[0070] It should be noted that the fiber segmentation state reflects the intensity of the effect of each segment on the bio-based fiber, so it can be used as a basis for adjustment to achieve directional correction of the shear path; by taking the fiber segmentation state as input, the distribution of the composite shearing effect in the shear path can be changed by adjusting the screw segment rotation speed and the entry position of the bio-based fiber, thereby reversing the adjustment of the bio-based fiber fracture process.

[0071] Furthermore, the coordinated adjustment of the rotation speed and the location of the bio-based fiber addition includes the following steps: Based on the fiber segmentation state of each screw section, the shear energy consumption demand distribution required by each section to maintain the target fiber length is calculated and mapped to the screw axial coordinate system; For example, there is a correspondence between the fiber segmentation state and the distribution of composite shear action, and the degree of fiber length shortening reflects the cumulative intensity of shear action in the screw segment. For each screw segment, the fiber length change result is read; this length change result is compared with the target fiber length to obtain the shear action trend that the screw segment needs to increase or decrease. Combined with the current composite shear action distribution intensity of the screw segment, the required shear energy consumption of the screw segment is calculated.

[0072] It should be understood that the shear energy consumption demand is used to characterize the energy level required for the screw section to cause the bio-based fiber to break. It can be determined by the combined shear action distribution and the material residence time. The shear energy consumption demand of each section is arranged according to the screw axial position to form a shear energy consumption demand distribution along the screw axial direction.

[0073] Adjust the drive speed of each screw section according to the demand distribution to match the real-time composite shear force distribution with the shear energy consumption demand distribution; It should be noted that the screw speed directly affects the shear strength and residence time of the material within the section, thus influencing the distribution of the combined shear action. For each screw section, the required trend of the combined shear action distribution is calculated based on its shear energy consumption requirements. By adjusting the drive speed of the screw section, the relative speed of the material within the screw section is changed. Simultaneously, the impact of speed changes on residence time is considered, thereby adjusting the cumulative effect of the shear action. When the speed increases, the shear action per unit time is enhanced; when the speed decreases, the material residence time increases, and the accumulation process of the shear action changes. Through the above adjustments, the actual distribution of the combined shear action in each section is made closer to the shear energy consumption requirement distribution.

[0074] Retrieve the position coordinates of multiple preset feeding ports along the screw axis, and determine the sequence of shear path segments covered by each feeding port to the screw discharge end; It should be noted that different feeding ports correspond to different shearing path starting points. Therefore, the shearing path length and segment combination experienced by the bio-based fiber after entering the system are different. The position of each feeding port in the screw axis is read, and for each feeding port, the set of screw segments subsequently covered by it is determined. The set of screw segments is arranged according to the shearing path sequence to form the shearing path segment sequence corresponding to the feeding port. The screw segment sequence is used to describe the complete shearing process experienced by the bio-based fiber after entering from the feeding port.

[0075] A correlation matrix is ​​established between the shearing path segment sequence and the fiber length evolution result. The feeding port that makes the fiber segmentation state meet the preset target is selected from multiple feeding ports. Different feeding ports correspond to different shearing paths, so their fiber length change results are different. By comparing the fiber length change results corresponding to different paths, a feeding position that better meets the target requirements can be selected.

[0076] Furthermore, the process of selecting the feeding port includes the following steps: Different feeding ports correspond to different shearing paths. For each candidate feeding port, the corresponding shearing path segment sequence is determined based on the position of the feeding port in the screw axis. For each screw segment in the screw segment sequence, the distribution of compound shearing action is read. The distribution of compound shearing action is spatially discretized within the screw segment to obtain multiple action units, and the shearing action intensity distribution of the screw segment is statistically analyzed. At the same time, based on the screw speed and material conveying relationship of the screw segment, the residence time of the material in the screw segment is calculated, and the residence time of each segment is arranged according to the path sequence to form the residence time sequence of that path.

[0077] It is understandable that each feeding port corresponds to a set of path characteristic data, including the distribution of compound shearing action in each segment and the residence time in each segment; forming a set of input parameters for subsequent length evolution calculations.

[0078] Different feeding ports correspond to different shearing paths. For the path feature data corresponding to each feeding port: take the feeding port as the starting point of the shearing path, and take the initial fiber length and orientation as input; perform stress calculation and fracture judgment segment by segment according to the segment order in the path; in each segment, update the fiber length segmentation state according to the combined effect of the composite shearing action distribution and residence time; take the segmentation result of the current segment as the input of the next segment, until the complete path is traversed.

[0079] Furthermore, after completing the full path calculation, the length segmentation results of all bio-based fibers are statistically analyzed. The lengths are divided into intervals, and the proportion of bio-based fibers in each interval is calculated to obtain the fiber length distribution results corresponding to the feeding port.

[0080] The target fiber length range is determined by the mechanical performance requirements of the composite material. For the fiber length distribution results corresponding to each feeding port, the proportion of bio-based fibers falling within the target length range is counted, and the proportion of bio-based fibers exceeding the target range is counted. When the proportion of bio-based fibers in the target range in the length distribution corresponding to a certain feeding port meets the preset conditions, the feeding port can be used as a candidate feeding position. The feeding ports that meet the conditions are summarized to form a set of candidate feeding ports.

[0081] In the candidate feed port set, different feed ports still correspond to different shear path complexities. The following comparison is performed on the candidate feed port set: the number of segments contained in the shear path corresponding to each feed port is calculated; and the number of segments with high intensity of compound shear action in the path is counted. The fewer the number of path segments, the shorter the shear process experienced by the bio-based fiber; or the fewer the number of high-shear segments, the lower the risk of breakage of the bio-based fiber. The feed port with a shorter shear path length or fewer high-shear segments is selected as the final feeding position. The actuator corresponding to the selected feed port issues a switching command to allow the bio-based fiber to enter the screw from the feed port, thereby updating the actual shear path.

[0082] Example 2 like Figure 2 As shown, this embodiment, based on embodiment 1, provides a multi-component automatic proportioning and blending molding system for bio-based composite materials. The system comprises a multi-component automatic proportioning module, a screw extrusion module, a parameter acquisition module, a shear action construction module, a shear path construction module, a fiber fracture calculation module, and a collaborative control module. Each module is connected via an industrial control bus and data interface, and is uniformly scheduled by a control unit.

[0083] The multi-component automatic proportioning module includes a recycled plastic feeding channel and a bio-based fiber feeding channel. The two materials enter the screw extrusion module via independent conveying devices. Recycled plastic enters through the main feed inlet at the front of the screw extrusion module; bio-based fiber enters through multiple lateral feed inlets spaced along the screw axis. Each feeding channel is connected to a mass flow control device, which adjusts the feeding rate by inputting control signals, ensuring that the recycled plastic and bio-based fiber enter the screw extrusion module in a set ratio.

[0084] Understandably, multiple feed ports constitute discrete spatial input positions, making the starting position of bio-based fibers entering the system adjustable, thereby affecting the subsequent shearing path.

[0085] The screw extrusion module internally houses a screw assembly and a barrel structure. The screw assembly is divided into multiple continuous sections along the axial direction. Each screw section has corresponding screw lead and screw clearance parameters, wherein: The screw lead determines the distance the material is propelled in the axial direction; The clearance between the screw threads determines the confined space for the material in the radial direction; The drive motor drives the screw to rotate through the transmission mechanism and receives control signals from the collaborative control module to adjust the speed. The structural differences in each section determine the spatial distribution characteristics of the composite shear action.

[0086] Parameter acquisition devices are arranged at each section of the screw extrusion module to obtain physical parameters during operation. Among them, the rotational speed is obtained from the feedback signal of the drive motor encoder; the torque is calculated from the motor load signal; the melt pressure is collected by the pressure sensor installed on the barrel wall; and the material temperature is obtained by the embedded temperature measuring element. The above parameters are synchronized through a unified time base, and each set of acquired data is matched with the axial position of the screw to establish the correspondence between parameters and spatial position, ensuring that the parameters in subsequent calculations are consistent with the actual position of action.

[0087] The shearing action construction module receives data output from the parameter acquisition module and establishes the material filling state in conjunction with the screw structure parameters. It determines the material's axial propulsion characteristics based on the screw lead, the radial constraint range based on the screw clearance, and the compression state of the material within the section based on the melt pressure distribution. The torque is divided into components acting on the axial propulsion region and components acting on the radial constraint region according to the spatial distribution, and converted into spatial shearing action based on the screw speed. The axial and radial shearing actions are superimposed in space to obtain the composite shearing action distribution of each screw section.

[0088] The shear path construction module describes the sequence and transmission relationship of shear actions experienced by bio-based fibers during processing. Based on the order of material conveying in each screw section, the composite shear action distribution is associated in axial order. At the boundary between adjacent sections, additional shear actions are introduced based on the change in melt pressure. At the same time, the range of shear action in each section is modified by combining the entry position and residence time of different components, so that the shear path can reflect the actual flow trajectory of the material, forming a shear path structure that includes the action nodes of the sections and the connection nodes.

[0089] The fiber fracture calculation module performs segment-by-segment calculations on the bio-based fiber based on the shear path, mapping the distribution of composite shear forces to the spatial distribution of the bio-based fiber; it calculates the tensile forces in the axial direction and the bending forces in the radial direction of the bio-based fiber; it identifies the tensile and bending regions within the bio-based fiber; when the two types of regions overlap at the same location, it segments the bio-based fiber; it uses the segmentation result of the current segment as the input condition for the next segment, passing the fracture process segment by segment, and finally outputs the fiber length distribution and fiber segmentation status.

[0090] The collaborative control module adjusts the system operating parameters based on the fiber segmentation status, determines the shearing adjustment direction of the corresponding segment according to the fiber length change of each segment, adjusts the screw speed by controlling the drive system, selects a new bio-based fiber addition position from multiple feeding ports, and after completing the parameter adjustment, re-triggers the shearing action construction module, shearing path construction module, and fiber breakage calculation module to form a cyclical update process. When the fiber length change result remains stable in continuous calculation, the current speed and feeding port position are locked.

[0091] By establishing a correspondence between the distribution of composite shear action and the material conveying path in the system, and calculating the fracture process of bio-based fibers segment by segment based on this path, and by coordinating the adjustment of rotation speed and feed port position, the spatial distribution of composite shear action is adjusted, thereby stabilizing the fiber length variation and improving the consistency of composite material performance.

[0092] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for automated blending and molding of multi-component bio-based composite materials, characterized in that, Includes the following steps: Based on a multi-component automatic proportioning system, recycled plastics and bio-based fibers are added to a screw extrusion unit, and the rotational speed, torque, melt pressure and material temperature of each screw section are collected during the material conveying process. Combining the screw lead and screw clearance, the torque and melt pressure are correlated to establish the material filling state in each screw section, and the torque is decomposed into a composite shearing action distribution along the screw axial and radial directions based on the material filling state. Based on the sequential relationship of material conveying in each screw section, the distribution of composite shearing action is correlated according to the material flow direction to form the shearing path experienced by bio-based fibers, and additional shearing action on bio-based fibers is introduced at the connection of adjacent sections due to changes in melt pressure; the range of action of each section in the shearing path is modified according to the residence distribution of different components in the screw, so that the shearing path changes with the material conveying process. Along the shear path, the bio-based fiber is subjected to a fracture action segment by segment according to the distribution of composite shear action in each segment, and the fiber length after the previous segment fracture participates in the fracture process of the next segment to obtain the fiber length change result; the fiber segmentation state of each screw segment is determined according to the fiber length change result and the mixed action relationship of the corresponding segment. Based on the fiber segmentation state of each screw section, the rotation speed and the addition position of the bio-based fiber in the corresponding section are adjusted in a coordinated manner. The addition position is selected from multiple feeding ports distributed along the screw axis. Based on the adjusted rotation speed and feeding port, the shearing path is reconstructed and the fiber length change process is repeated. When the fiber length change result is in a stable range, the corresponding rotation speed and feeding port are locked.

2. The method for automatic blending and molding of multi-component bio-based composite materials according to claim 1, characterized in that, The method of decomposing the torque into a composite shear force distribution along the screw axial and radial directions based on the material filling state includes the following steps: Obtain the helical propulsion space parameters corresponding to the screw lead and the radial constraint space parameters corresponding to the screw clearance, construct the spatial occupancy profile of the material in the screw section, and map the real-time collected melt pressure distribution to the spatial occupancy profile; Based on the distribution ratio of the material in the axial propulsion vector and the radial spreading vector in the space-occupying contour, the total torque is decoupled into a first component acting on the axial propulsion region and a second component acting on the radial constraint region within the same segment. Combining the screw rotational angular velocity, the first component is converted into a first shear force transmitted along the screw axis, and the second component is converted into a second shear force transmitted along the screw radially. The first and second shear forces are vector-synthesized to obtain the composite shear force distribution for each screw segment, which serves as the input parameter for constructing the shear path.

3. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 2, characterized in that, The process of constructing the spatial occupancy contour includes: The axial compression ratio of the material is determined based on the melt pressure gradient between adjacent screw sections, thus defining the axial occupancy range of the material within the section. Based on the axial occupancy range, and combined with the geometric radial boundary of the screw thread gap, the expansion limit of the material in the radial direction is calculated to form the radial occupancy range; By integrating the axial and radial occupancy regions, a three-dimensional spatial occupancy profile of the material within the screw channel is generated. The three-dimensional spatial occupancy contour is coupled and matched with the melt pressure field to output a dynamic filling state model for torque decomposition.

4. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 1, characterized in that, The correction of the effective range of each segment in the shearing path includes the following steps: Identify the feeding sequence and feed port coordinates of recycled plastics and bio-based fibers in each screw section, and determine the initial distribution phase of each component in the screw axis; Based on the initial distribution phase and material flow rate, the dynamic residence time of each component in each screw section and the actual covered section range are calculated in real time. Monitor the melt pressure change vector at the junction of adjacent screw sections to determine the axial overflow or backflow offset of the material at the junction, and define the physical extension area of ​​shear action to adjacent sections accordingly. The actual covered segment range and the physical extension area are superimposed to update the effective boundary of the shear path.

5. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 4, characterized in that, The process of determining the shear propagation region based on the direction of melt pressure change includes: Fit the axial pressure gradient curve at the junction of adjacent screw sections and extract the transmission vector of pressure fluctuation; Based on the transfer vector, determine the advance or lag distance of the material flow at the section junction and identify the deviation parameters of the motion path; The effective points of the combined shear force distributed in the spatially occupied contour are extended along the direction deviating from the parameter to generate the shear force field extension region; The generated extended region is incorporated into the current shear path model as a modified boundary condition for the simulation of bio-based fiber fracture.

6. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 1, characterized in that, Obtaining the fiber length change results includes the following steps: According to the physical arrangement order of each screw segment in the shear path, extract the force vector of the composite shear action distribution corresponding to each segment and its three-dimensional coordinate action position in the spatial contour. Within each screw section, the composite shear force distribution vector is mapped to the real-time distribution area of ​​the bio-based fiber in the spatial contour, and the axial tensile stress and radial bending moment borne by the bio-based fiber within the screw section are calculated. The fiber length state after the current screw section is processed is used as the iterative input condition for the next screw section, and the composite shearing action distribution is accumulated in subsequent sections to form a cumulative fracture process that is transmitted segment by segment during the material conveying process. Traverse all screw segments involved in the shearing path and output the final length distribution data of the bio-based fiber as a quantitative basis for determining the fiber segmentation state.

7. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 6, characterized in that, The process of forming the fiber segmentation state includes the following steps: Identify the physical contact points between the composite shear force distribution and the bio-based fiber in the spatial occupancy profile, and mark the relative displacement of the contact points with respect to the centroid of the bio-based fiber. Based on the gradient distribution of axial tensile stress in the axial direction of bio-based fibers, the vulnerable tensile regions of bio-based fibers are determined. Based on the curvature distribution of the radial bending moment in the spatially occupied profile, the spatial critical region for nonlinear bending deformation of bio-based fibers is determined. When the tensile region and the spatial critical region spatially overlap at the same coordinate on the bio-based fiber and the stress value exceeds the preset fracture threshold, a fracture node is generated at that location, and the bio-based fiber is discretized and segmented to update the fiber segmentation status of the current segment.

8. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 1, characterized in that, The coordinated adjustment of the rotation speed and the addition position of the bio-based fiber in the corresponding section includes the following steps: Based on the fiber segmentation state of each screw section, the shear energy consumption demand distribution required by each section to maintain the target fiber length is calculated and mapped to the screw axial coordinate system; Adjust the drive speed of each screw section according to the demand distribution to match the real-time composite shear force distribution with the shear energy consumption demand distribution; Retrieve the position coordinates of multiple preset feeding ports along the screw axis, and determine the sequence of shear path segments covered by each feeding port to the screw discharge end; Establish a correlation matrix between the shearing path segment sequence and the fiber length evolution result, and select the feed port from multiple feed ports that makes the fiber segmentation state meet the preset target.

9. The method for automatic proportioning and blending of multi-component bio-based composite materials according to claim 8, characterized in that, The process of selecting the feeding port includes the following steps: For each alternative feeding port, extract the composite shear force distribution characteristics and material residence time distribution of each segment within the sequence. The fiber length change after entering each feeding port was simulated and pre-calculated using the fracture transmission mechanism of bio-based fibers to obtain the statistical distribution of fiber length at different feeding positions. By performing a matching degree analysis between the pre-calculation results and the target fiber length range, a set of candidate feeding ports that meet the mechanical performance requirements is identified. In the set of candidate feeding ports, the feeding port with the shortest corresponding shearing path length or the fewest shearing peak segments is selected as the final feeding position, and the switching command of the actuator is executed to update the physical shearing path.

10. A multi-component automated proportioning and blending molding system for bio-based composite materials, used to perform the multi-component automated proportioning and blending molding method for bio-based composite materials according to any one of claims 1-9, characterized in that, It includes a multi-component automatic proportioning module, a screw extrusion module, a parameter acquisition module, a shear action construction module, a shear path construction module, a fiber breakage calculation module, and a collaborative control module; The multi-component automatic proportioning module is connected to the screw extrusion module and is used to add recycled plastic and bio-based fiber into the screw extrusion module through different feeding ports. The parameter acquisition module is set at the position of each screw section corresponding to the screw extrusion module, and is used to collect the rotation speed, torque, melt pressure and material temperature of each screw section, and establish a corresponding relationship according to the axial position of the screw; The shearing action construction module is connected to the parameter acquisition module. It is used to correlate the torque and melt pressure by combining the screw lead and screw clearance, establish the material filling state of each screw section, and decompose the torque into a composite shearing action distribution along the screw axis and radial direction. The shear path construction module is connected to the shear action construction module. It is used to associate the composite shear action distribution according to the material flow direction based on the material conveying relationship in each screw section, forming a shear path experienced by the bio-based fiber. It also introduces melt pressure changes at the connection of adjacent sections to form a pre-shear action, and corrects the range of action of the shear path according to the residence distribution of different components in the screw. The fiber breakage calculation module is connected to the shear path construction module. It is used to apply a compound shearing action to the bio-based fiber segment by segment along the shear path, and use the fiber length state of the previous screw segment as the input condition for the next screw segment to obtain the fiber length change result. Based on the fiber length change result, the fiber segmentation state of each screw segment is determined. The collaborative control module is connected to the fiber breakage calculation module and the screw extrusion module. It is used to adjust the rotation speed of the corresponding section according to the fiber segmentation state of each screw section, select the addition position of bio-based fiber from multiple feeding ports distributed along the screw axis, update the shear path based on the adjusted rotation speed and feeding port position, and lock the corresponding rotation speed and feeding port when the fiber length change result is in a stable range.

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