Continuous extruder for producing plastic hollow plate

Abstract

The invention relates to a continuous extruder for producing a plastic hollow plate, and belongs to the technical field of high polymer material processing. Comprising a main feeding system, a high-shear double-screw extruder, an integrated melt regulation and control system, a dynamic adjustable flow dividing and distributing mechanism, a forming die head and a heat-flow synergistic shaping unit which are connected in sequence, as well as a central control unit and a flow dividing valve group. The dispersion uniformity of the melt is improved through ultrasonic-assisted re-homogenization and magneto-rheological shear enhanced mixing, and the rheological consistency is controlled through dynamic temperature compensation of melt viscoelasticity feedback; according to a product specification instruction, the central control unit drives the diverter valve group to realize melt distribution as required; and after extrusion, mold release expansion and surface temperature are monitored in real time. According to the invention, the melt mixing uniformity is obviously improved, the product switching time is shortened, the wall thickness variation coefficient is reduced, and the production efficiency and the product quality are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer material processing technology, specifically relating to a continuous extruder for producing plastic hollow boards. Background Technology

[0002] Plastic hollow boards, as a functional material combining lightweight, high strength, corrosion resistance, and recyclability, have been widely used in various industrial fields such as logistics packaging, building partitions, advertising displays, and transportation. With the increasing demands from downstream applications for material performance, dimensional accuracy, and production cost control, continuous, efficient, and intelligent production of plastic hollow boards has become an important direction for the development of polymer material processing technology. Continuous extrusion molding, with its advantages of strong production continuity, high molding efficiency, and good product consistency, has become the mainstream manufacturing method. However, facing the market's urgent demand for product diversification, customization, and high performance, the limitations of traditional extrusion processes in terms of equipment adaptability, raw material handling capacity, and molding control precision are gradually becoming apparent, necessitating a system-level restructuring and optimization of the process path and equipment structure.

[0003] Invention patent CN118927559B discloses a continuous extruder for plastic hollow sheets. By setting multiple diversion and transfer mechanisms and matching molding dies at the rear end of the main extrusion system, it realizes the technical concept of parallel extrusion of hollow sheets of different specifications on the same production line. This solution, to a certain extent, breaks through the capacity bottleneck of traditional single-die single-output and improves the output diversity of the equipment. Simultaneously, this solution introduces a secondary mixing section into the extrusion screw structure, utilizing the screw's shearing action to re-mix the plasticized raw materials, thereby improving the dispersion uniformity between different components.

[0004] The invention patent with announcement number CN104260962B discloses a one-time molding hollow packaging box, a continuous extrusion equipment for producing the hollow packaging box, and a production process. It focuses on the one-time molding process of structural components. By optimizing the integrated design of the die flow channel and the shaping unit, the overall extrusion of the hollow packaging box body is achieved, reducing subsequent assembly processes and improving the structural integrity and mechanical reliability of the product.

[0005] As plastic products continue to evolve towards higher performance, greater precision, and lower carbon emissions, the structural contradictions inherent in the aforementioned technical solutions at the principle level are becoming increasingly prominent. While parallel configuration of multiple molds improves the parallel capability of specification switching, it still relies on physical redundancy to achieve functional expansion, resulting in a significant increase in the longitudinal dimensions of the equipment, reduced space utilization, and the possibility of flow imbalance caused by differences in rheological resistance during melt distribution in each branch channel, which in turn makes it difficult to guarantee the consistency of wall thickness for products of different specifications.

[0006] When changing to a mold of a certain specification, this type of system often requires a shutdown to adjust the entire diversion and transfer unit, and the actual flexibility is not significantly improved. Although the secondary stirring mechanism based on screw shearing can enhance the mixing effect, for high-viscosity melts or complex formulation systems containing a high proportion of functional additives (such as flame retardants and antibacterial masterbatches), its mixing intensity is limited by the screw length-to-diameter ratio and the length of the shearing zone, making it difficult to achieve homogeneous distribution at the microscale. This easily leads to local component enrichment or insufficient dispersion, which ultimately manifests as fluctuations in the mechanical properties of the product or defects such as fisheyes and streaks on the surface.

[0007] Existing technologies generally neglect the cumulative influence of the thermal history and shear history of the melt during the pre-mold conveying process on its rheological behavior, and lack a coordinated control mechanism for the temperature field and stress field. As a result, when the melt enters the forming die, there are already local temperature differences or uneven elastic energy storage, which induces forming defects such as deformation, warping or internal stress concentration during the subsequent mold expansion and shaping process. Summary of the Invention

[0008] The purpose of this invention is to provide a continuous extruder for the production of plastic hollow boards, which solves the technical problems of poor melt uniformity, unstable rheological state and low product dimensional accuracy in the continuous extrusion production of multi-specification plastic hollow boards.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A continuous extruder for producing plastic hollow boards includes: a main feeding system, a high-shear twin-screw extruder, an integrated melt control system, a dynamically adjustable flow distribution mechanism, a forming die and a heat-fluid co-forming unit, as well as a central control unit and a flow distribution valve group connected in sequence.

[0011] The continuous extruder operation method includes the following steps:

[0012] Multiple polymer raw materials and functional additives are fed into the main feeding system according to a preset ratio. The mixture is then plasticized and primary mixed by a high-shear twin-screw extruder. The resulting melt is then transported to an integrated melt control system, where it undergoes ultrasonic-assisted re-homogenization, magnetorheological shear-enhanced mixing, and dynamic temperature compensation based on melt viscoelastic feedback. Subsequently, it enters a dynamically adjustable flow distribution mechanism. According to the target product specifications, the central control unit drives the flow distribution valve group to execute a predetermined opening and closing sequence, distributing the homogeneous melt to the corresponding forming die head according to the set flow rate ratio. After being extruded through the die head, the melt enters the heat-fluid co-forming unit. This unit dynamically adjusts the cooling air velocity field and vacuum adsorption pressure gradient based on real-time collected data on die expansion and surface temperature distribution, ultimately forming a dimensionally stable, uniformly thick plastic hollow board, thus completing continuous production.

[0013] Furthermore, the main feeding system includes at least two loss-in-weight metering feeders, used for independent feeding of the main matrix resin and high-concentration functional masterbatch, respectively. Each feeder is equipped with a closed-loop weight feedback controller with a sampling frequency of 100Hz and a control accuracy of ±0.3%. The feeder outlet is connected to the side feed port of the twin-screw extruder via a rigid flange, ensuring that the material is pre-mixed before entering the screw compression section. The twin-screw extruder adopts a co-rotating parallel twin-screw structure with a total screw length-to-diameter ratio of 36:1, divided into five functional sections:

[0014] The first section is the conveying section, with a screw groove depth of 4.5mm;

[0015] The second section is the compression section, where the screw groove depth gradually decreases from 4.5mm to 2.5mm;

[0016] The third section is the melting section, equipped with kneading discs, with a disc thickness of 5mm and a staggered angle of 30°;

[0017] The fourth section is the primary mixing section, equipped with a reverse thread element and a lead of 24mm; the fifth section is the homogenization section, equipped with a single-start thread element and a lead of 36mm. The screw speed is driven by an AC servo motor, with an adjustment range of 50rpm to 300rpm and a speed control accuracy of ±1rpm. The barrel is equipped with a segmented electric heating coil and an annular water cooling channel. Each temperature control zone is 120mm long, with a temperature control range of 160℃ to 220℃ and a temperature control accuracy of ±0.5℃.

[0018] Furthermore, the integrated melt control system is located downstream of the twin-screw extruder outlet and connected via a metal hose. The system includes a melt pipeline, an ultrasonic homogenizing unit, a magnetorheological mixing unit, and a dynamic temperature compensation module. The melt pipeline is made of 316L stainless steel, with an inner diameter of 60mm and a wall thickness of 8mm. The inner wall of the pipeline is mirror-polished, with a surface roughness Ra≤0.4μm. A constant-power electric heating tape is wrapped around the outside of the pipeline to maintain a basic conveying temperature of 200℃±2℃. The ultrasonic homogenizing unit is installed in the middle of the melt pipeline and includes four circumferentially distributed piezoelectric ceramic transducers with a central excitation frequency of 28kHz and a maximum output sound intensity of 15W / cm². The transducers are coupled to the inner wall of the pipeline via titanium alloy amplitude transformers. The end of the amplitude transformer extends 2mm into the pipeline, forming a standing wave field action zone. The standing wave field covers an axial length of 150mm and is used to apply high-frequency mechanical vibration to the melt, breaking up agglomerated particles and promoting the deentanglement of molecular chains.

[0019] Furthermore, the magnetorheological mixing unit is located 500mm downstream of the ultrasonic homogenizing unit and includes a ring-shaped electromagnetic coil, magnetic pole shoes, and a magnetic field control power supply. The electromagnetic coil is wound around the outer circumference of the melt pipe with 1200 turns, using copper-clad aluminum wire with a cross-sectional area of ​​6mm² and an insulation class of H. The magnetic pole shoes are made of electrical pure iron with a relative permeability μr≥4000. Eight symmetrically distributed pole shoes are arranged along the circumference of the pipe, with a distance of 3mm between the end face of the pole shoes and the outer wall of the pipe, forming a closed magnetic circuit. The magnetic field control power supply outputs a DC current ranging from 0A to 20A with a response time of less than 50ms, which can generate a radial gradient magnetic field with a maximum magnetic induction intensity of 0.8T inside the pipe. The pipe section covered by the gradient magnetic field constitutes the magnetic field action zone. When the functional additive containing magnetic nanoparticles passes through the magnetic field action zone with the melt, the particles form a chain structure under the action of the magnetic field, significantly enhancing the interfacial shear stress and achieving micron-scale dispersion strengthening.

[0020] Furthermore, the dynamic temperature compensation module is located 300mm downstream of the magnetorheological hybrid unit and includes a distributed temperature sensor array, an infrared thermal imager, and a rapid heating / cooling actuator. The temperature sensor array consists of six platinum resistance temperature probes, equidistantly arranged along the circumference of the pipe. The probe insertion depth is 5mm, the sampling period is 100ms, and the measurement accuracy is ±0.3℃, used for real-time monitoring of the radial temperature distribution of the melt. The infrared thermal imager is installed directly above the pipe, with a field of view of 45°, a spatial resolution of 0.5mm / pixel, and a frame rate of 60fps, used for capturing… The axial temperature fluctuation of the melt surface is captured. The rapid heating / cooling actuator consists of an embedded ceramic heating element and a micro-nozzle array. The heating element has a power density of 15W / cm², a response time of less than 1s, a nozzle orifice diameter of 0.8mm, and an adjustable airflow speed range of 5m / s to 30m / s. The central control unit dynamically adjusts the heating power or cooling gas flow rate based on the temperature deviation signal using a PID control algorithm (proportional gain Kp=2.5, integral time Ti=10s, derivative time Td=1s) to keep the temperature standard deviation of the melt within ±1.0℃ before entering the distribution mechanism.

[0021] Furthermore, the dynamically adjustable diversion and distribution mechanism includes a main pipeline, a diversion valve group, branch pipelines, and a pressure-flow monitoring unit. The main pipeline is connected to the outlet flange of the integrated melt control system and has an inner diameter of 60mm. There are four branch pipelines, each corresponding to a molding die for four standard specifications of hollow plates. The inner diameters of the branch pipelines are 60mm, 50mm, 40mm, and 35mm, respectively, to match the die requirements for different cross-sectional areas. Each branch pipeline inlet is equipped with an electric proportional ball valve. The valve core material is silicon nitride ceramic with a hardness of HRA≥90, and the sealing ring is perfluoroether rubber with a temperature resistance rating of 300℃. The valve is driven by a stepper motor with a step angle of 1.8°, equipped with an absolute encoder, an angular displacement resolution of 0.018°, and an opening adjustment accuracy of ±0.5%.

[0022] The pressure-flow monitoring unit includes a differential pressure sensor and a Coriolis mass flow meter. The differential pressure sensor has a range of 0 MPa to 10 MPa and an accuracy class of 0.25%. It is installed before and after the inlet of each branch pipe to measure the pressure drop before and after the valve. The mass flow meter has a range of 0 kg / h to 2000 kg / h and an accuracy of ±0.1%. It is used to obtain the melt mass flow rate of each branch in real time. All sensor data are uploaded to the central control unit at 10 ms intervals.

[0023] Furthermore, the central control unit executes a diversion logic control program based on preset product specification instructions. This program includes a specification matching subroutine, a flow balancing subroutine, and a fault self-diagnosis subroutine. The specification matching subroutine calls the corresponding diversion valve opening / closing combination matrix according to the product code input by the operator. For example, when producing specification A, only the first branch valve is opened and the other three are closed; when producing a combination of specifications B and C, the second and third branch valves are opened simultaneously, and the flow is distributed according to a mass ratio of 7:3. The flow balancing subroutine uses a feedforward-feedback composite control strategy based on the mass flow meter feedback value. It uses the actual flow rate of the previous extrusion cycle as the feedforward reference and adjusts proportionally based on the current deviation to ensure that the actual flow rate of each activated branch deviates from the set value by less than ±1.5%. The fault self-diagnosis subroutine continuously monitors the valve position feedback, pressure mutations, and abnormal flow fluctuations. When it detects that the flow rate of a branch is lower than 80% of the set value for more than 3 seconds, it determines a blockage risk and automatically triggers the reverse flushing program for that branch, i.e., briefly opening the reverse pneumatic valve to introduce compressed air for reverse purging for 2 seconds at a pressure of 0.6 MPa.

[0024] Furthermore, the forming die head includes a die body, a flow divider, a die plate, and an adjustment mechanism. The die body is made of H13 hot work die steel, and is quenched and tempered to a hardness of 48HRC to 52HRC. A spiral flow divider channel is provided inside the die body, with an Archimedean spiral cross-section, a starting radius of 30mm, an ending radius of 80mm, a pitch of 100mm, and two and a half turns, ensuring that the melt is evenly distributed circumferentially before entering the die. The flow divider is fixed at the center of the die body and has a streamlined spindle shape. The front end has a radius of curvature of 25mm and a rear end cone angle of 15°. The surface is coated with a CrN coating with a thickness of 25μm and a friction coefficient μ≤0.15. The die template is detachably installed at the front end of the die body and is fastened with eight M16 hexagon socket screws with a preload torque of 120N·m. The die template has a core mold and an outer mold corresponding to the target hollow plate structure, forming an annular extrusion gap between them. The gap width is set according to the product wall thickness, ranging from 1.5mm to 4.0mm, with an adjustment accuracy of 0.1mm.

[0025] Furthermore, the heat-flow synergistic shaping unit includes a shaping sleeve, a cooling air box, a vacuum adsorption system, and an online detection module. The shaping sleeve is made of aluminum alloy and has an internal forming cavity that matches the outer contour of the hollow plate. The cavity is 1200mm long and divided into three temperature zones, each with independent temperature control. The first temperature zone is set to 85℃, the second to 65℃, and the third to 45℃. The temperature control method is internal flow channel circulation of heat transfer oil, with an oil temperature control accuracy of ±1℃. The cooling air box is located at the outlet end of the shaping sleeve and includes upper and lower sets of air knives. The air knife slit width is 1.0mm, the air pressure is adjustable from 1.5kPa to 6.0kPa, and the wind speed distribution uniformity error is less than ±5%. The air source is a centrifugal fan with an air volume of 8000m³ / h, and the air passes through an air filter (filtration class ISO 8573-1 Class). 2) After processing, the air knife is fed into the vacuum adsorption system, which consists of a vacuum pump, a distribution valve and an adsorption hole array. The ultimate pressure of the vacuum pump is 100 Pa and the pumping speed is 120 L / s. The adsorption holes are distributed on the inner wall of the shaping sleeve, with a hole diameter of 1.2 mm and a hole spacing of 20 mm × 20 mm, arranged in a square array. The vacuum degree is set to -60 kPa to prevent the hollow plate from deforming during the cooling process.

[0026] Furthermore, the online detection module includes a laser displacement sensor, an infrared thermal imager, and a machine vision system. Four laser displacement sensors are arranged at the top, bottom, left, and right positions of the hollow board's cross-section, with a measurement range of 0mm to 50mm, a resolution of 1μm, and a sampling frequency of 1kHz, used to acquire wall thickness data in real time. The infrared thermal imager monitors the surface temperature field of the hollow board at a frame rate of 30fps and a temperature resolution of 0.1℃. The machine vision system includes a line-scan camera and an LED backlight. The camera has a resolution of 4096 pixels and a scanning frequency of 20kHz, used to identify surface defects such as fisheyes, scratches, or color differences. All detection data is transmitted to the central control unit at 100ms intervals for closed-loop control.

[0027] Furthermore, the central control unit executes a heat-flow coordinated control algorithm based on the wall thickness deviation and surface temperature gradient fed back by the online detection module. When the wall thickness on a certain side exceeds the tolerance zone (±0.1mm), the system automatically adjusts the cooling air knife pressure on the corresponding side to increase the cooling intensity and suppress mold expansion. The adjustment step is 0.2kPa, and the maximum adjustment range is ±1.5kPa. When the surface temperature difference exceeds 5℃, the heat transfer oil flow regulating valve is activated to change the heating / cooling power of the corresponding temperature zone, so that the temperature gradient is restored to within 2℃. When the machine vision system detects the same type of defect for three consecutive cycles, the system records the defect location and process parameter combination, and generates an early warning signal to prompt the operator to check the raw material batch or mold cleaning status.

[0028] Furthermore, this invention also discloses a rapid mold replacement mechanism. This mechanism achieves automated mold replacement through a standardized interface, which includes a positioning pin, a hydraulic clamping cylinder, and an electrical connector. The positioning pin has a diameter of 20mm and a tolerance grade of H7 / g6, ensuring a repeatability accuracy of less than 0.02mm. The hydraulic clamping cylinder has a working pressure of 10MPa, a clamping force of 40kN, and an action time of less than 8s. The electrical connector is used to transmit heating rod and thermocouple signals and has a mating life of more than 100,000 cycles. The replacement process is performed by a robotic arm, which retrieves the target mold from the mold library, aligns it with the positioning pin, inserts it, activates the hydraulic clamping, and completes the electrical connection. The entire process takes no more than 90s. During this time, the main extrusion system maintains a low speed (50rpm), and the melt circulates in the main pipeline with the diversion valve closed to avoid degradation during downtime.

[0029] Furthermore, this invention also discloses a melt residence time optimization strategy. By adjusting the synergistic relationship between the twin-screw extruder speed, the diverter valve opening, and the molding traction speed, the total residence time of the melt from the feed to the extruder outlet is controlled within the range of 180s to 240s. For heat-sensitive materials such as polyvinyl chloride (PVC), the upper limit is set to 210s, and for high-temperature stable materials such as polypropylene (PP), it can be extended to 240s. The residence time calculation model is based on the screw conveying rate, pipeline volume, and flow distribution ratio, and is calculated in real time by the central control unit and displayed on the human-machine interface.

[0030] Furthermore, it includes an energy consumption monitoring and optimization module, which integrates an energy meter, flow meter, and temperature sensor to collect real-time energy consumption data of the main motor, heating system, and cooling system, and establishes a unit product energy consumption index (kWh / kg). When this index exceeds the benchmark value by 10% for five consecutive batches, the system automatically starts an energy efficiency diagnosis program to analyze whether there are problems such as overheating of the heating zone, excessive cooling water flow, or abnormal screw back pressure, and recommends parameter adjustment schemes, such as lowering the temperature of the third heating zone by 5°C or reducing the cooling water flow by 15% to achieve low-carbon operation.

[0031] Furthermore, the functional additives used include flame retardants, antibacterial agents, UV stabilizers, and toughening agents. The flame retardant is decabromodiphenyl ethane, added at 15 wt%, with a particle size D90 ≤ 10 μm; the antibacterial agent is silver-loaded zirconium phosphate, added at 2 wt%, with a specific surface area ≥ 150 m² / g; the UV stabilizer is a benzotriazole compound, added at 0.8 wt%, with an absorption peak at 340 nm; and the toughening agent is maleic anhydride-grafted polyolefin elastomer, added at 8 wt%, with a grafting rate ≥ 1.5%. All additives are premixed for 30 min in a high-speed mixer at 1200 rpm before being added to the main feeding system, with a mixing uniformity variation coefficient of less than 3%.

[0032] Furthermore, the plastic hollow board structure involved in the method is a double-walled or multi-walled honeycomb structure, with continuous supporting ribs connecting the walls. The supporting ribs have a trapezoidal cross-section, with an upper base width of 2mm, a lower base width of 4mm, a height of 6mm, and a spacing of 20mm. The overall board thickness ranges from 3mm to 15mm, the width ranges from 1000mm to 2000mm, and the length is unlimited. The product density is 0.4g / cm³ to 0.6g / cm³, the flexural modulus is greater than 1500MPa, and the drop hammer impact strength is greater than 40kJ / m², meeting the requirements of GB / T 13520-2018 "Rigid Polyvinyl Chloride Sheets" and ISO 1133-1:2011 melt flow rate test.

[0033] Furthermore, all control signal transmissions adopt the industrial Ethernet protocol with a communication rate of 100Mbps. The network topology is a ring redundant structure, supporting PROFINET IRT real-time communication with a data refresh cycle of 1ms, ensuring that the synchronization error between subsystems is less than 10μs. The central control unit hardware platform adopts a dual redundant PLC controller with a CPU frequency of 1.2GHz, 4GB of memory, and runs a real-time operating system. It has a power failure retention function and can store no less than 1000 process recipes, each recipe containing no less than 200 parameter items.

[0034] Furthermore, when the melt pressure is detected to rise sharply by more than 20% above the set value, the system automatically initiates a pressure relief procedure, opens the bypass valve to guide part of the melt into the recovery tank, and simultaneously reduces the screw speed by 10%. Production is gradually resumed after the pressure returns to normal. When the cooling water temperature is 5°C higher than the set value, the standby cooling tower fan is started and an equipment maintenance reminder is issued. When the mismatch between the traction speed and the extrusion rate exceeds ±3%, the system suspends the diversion operation and prioritizes stable extrusion of a single path until the parameters are recalibrated.

[0035] Furthermore, the setting range of the process parameters is as follows:

[0036] The twin-screw extruder has the following temperature zones: 160℃~220℃; screw speed: 50rpm~300rpm; melt pressure: 10MPa~25MPa; die extrusion temperature: 195℃~205℃; shaping sleeve temperature zones: 80℃~90℃ (first zone), 60℃~70℃ (second zone), 40℃~50℃ (third zone); cooling air pressure: 1.5kPa~6.0kPa; vacuum degree: -50kPa~-70kPa; traction speed: 0.5m / min~15m / min; diverter valve response time: less than 100ms; temperature control accuracy: ±0.5℃; pressure measurement accuracy: ±0.1MPa; flow control accuracy: ±0.1%; wall thickness control accuracy: ±0.1mm; and product straightness error: less than 1mm / m.

[0037] Furthermore, by integrating ultrasonic homogenization, magnetorheological mixing, and dynamic temperature compensation technologies, the uniformity of melt mixing is increased to more than 2.3 times that of the traditional secondary stirring process without increasing the screw length-to-diameter ratio. Taking pigment dispersion testing as an example, the particle size distribution is determined by microscopic image analysis. The number density of agglomerates larger than 5μm in the sample obtained by the method of this invention is less than 8 / mm², while the traditional process is 22 / mm².

[0038] Meanwhile, through a dynamically adjustable flow distribution mechanism, seamless switching between the four product specifications is achieved, reducing the average switching time from 45 minutes of traditional downtime for mold changing to less than 90 seconds, and increasing the overall equipment efficiency (OEE) from 68% to 89%. In addition, through heat-flow synergistic shaping control, the product wall thickness variation coefficient is reduced from 3.5% to below 1.2%, and the warpage is reduced from 5.2mm / m to 1.8mm / m, significantly improving the product's dimensional stability and appearance quality.

[0039] Furthermore, in this invention, all material contact components comply with FDA 21 CFR 177.1520 and EU 10 / 2011 food contact material regulations. The overall protection rating of the equipment is IP54, the noise level is less than 75 dB(A), and it meets the GB5226.1-2019 mechanical and electrical safety standards. The entire line is equipped with an emergency stop button, safety light curtain, and interlocking devices to ensure the safety of operators.

[0040] Furthermore, this invention is applicable to the continuous extrusion production of hollow sheets of various thermoplastic plastics such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) and acrylonitrile-butadiene-styrene copolymer (ABS), and is especially suitable for the processing of highly filled, blended modified and multi-layer composite materials, and has a wide range of material adaptability and process compatibility.

[0041] Furthermore, the central control unit also integrates a process simulation module. The process simulation module establishes a melt flow and heat transfer model based on the finite element method, with a mesh number of no less than 500,000 and a time step of 0.01s. It can predict the pressure distribution, temperature field evolution, and shear rate changes under different combinations of formulations and process parameters, and is used to pre-test the feasibility of new products and optimize the initial parameter settings to reduce trial and error costs.

[0042] Furthermore, the ultrasonic homogenizing unit and the magnetorheological mixing unit of the integrated melt control system can be started and stopped independently, and the activation mode can be selected according to the characteristics of the raw material system: for ordinary blends, only ultrasonic homogenization is activated; for functional composite materials containing magnetic particles, both ultrasonic and magnetorheological effects are activated simultaneously; for materials with poor thermal stability, ultrasonic is turned off to avoid local overheating, and only magnetorheological shear strengthening is relied upon.

[0043] Furthermore, the number of branch lines of the dynamically adjustable diversion and distribution mechanism can be expanded to six according to the production line configuration. Flexible expansion is achieved through modular design. The valves and sensor interfaces of the newly added branch lines follow a unified communication protocol and mechanical interface standard, which facilitates system upgrades and maintenance.

[0044] Furthermore, the surface of the shaping cavity of the heat-flow synergistic shaping unit is coated with a polytetrafluoroethylene (PTFE) coating with a thickness of 30 μm and a surface energy of less than 25 dyn / cm, which effectively reduces the frictional resistance between the hollow plate and the shaping surface, prevents scratches and adhesion, and extends the continuous operation cycle.

[0045] Furthermore, the data from the online testing module is used to build a product quality traceability system. Each hollow board generates a unique electronic tag to record its production time, process parameters, raw material batch, and test results. The data is stored for no less than five years and supports QR code scanning for querying and quality analysis.

[0046] Furthermore, the traction device adopts a dual-track structure, with the track surface covered with polyurethane material, a hardness of 85 Shore A, a traction roller diameter of 200mm, an adjustable traction force range of 5kN to 20kN, and a speed control accuracy of ±0.1%, ensuring stable output and avoiding tensile deformation.

[0047] Furthermore, the abnormal melt collected in the recycling tank can be crushed, cleaned and dried, and then reintroduced into the main feeding system as recycled material. The proportion of recycled material is controlled within 15%, which does not affect the performance of the final product and realizes resource recycling.

[0048] Furthermore, the timing of all actuator actions is uniformly scheduled by the central control unit, forming a strict time sequence control chart. The triggering error of each action is less than ±5ms, ensuring the coordination and stability of the entire extrusion process.

[0049] Furthermore, the Reynolds number Re of the melt in the distribution mechanism is controlled between 80 and 120, which is in the laminar flow transition zone to avoid pressure fluctuations and energy loss caused by turbulence. The flow velocity in the pipeline is set to 0.15 m / s to 0.25 m / s to meet the requirements for stable delivery of high-viscosity melt.

[0050] Furthermore, the extrusion gap of the template is adjusted by precision shims with thicknesses of 0.1mm, 0.2mm, 0.3mm, and 0.5mm, made of stainless steel, and with a surface flatness better than 0.01mm, ensuring uniform gap.

[0051] Furthermore, the central control unit is equipped with a remote monitoring interface that supports 4G / 5G wireless communication, allowing technicians to access device status, modify parameters, and receive alarm information through an encrypted channel, thereby achieving intelligent operation and maintenance management.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] This invention utilizes an ultrasonic-assisted rehomogenization unit to break down van der Waals forces between aggregated particles through cavitation and microjets generated by high-frequency mechanical vibration, promoting molecular chain deentanglement. A magnetorheological shear-enhanced mixing unit manipulates magnetic nanoparticles to form dynamic chain structures via a gradient magnetic field, establishing a microscale high-shear region within the melt and significantly enhancing interfacial mass transfer efficiency. The spatiotemporal synergy of these two mechanisms overcomes the diffusion rate limitations of traditional screw shear mixing, achieving a highly uniform distribution of melt components at the microscale.

[0054] This invention uses a dynamic temperature compensation mechanism based on melt viscoelastic feedback to treat rheological parameters as direct control variables. It captures changes in the thermodynamic state of the melt in real time through a distributed sensor network and uses a rapid heating and cooling actuator to perform localized and precise compensation of the temperature field. This ensures that the melt has highly consistent rheological properties before entering the molding stage, effectively suppressing molding defects caused by differences in thermal history.

[0055] The dynamic adjustable flow distribution mechanism of this invention is based on the principle of fluid dynamics. It accurately matches the flow resistance characteristics of each branch through a feedforward feedback composite control strategy. The central control unit dynamically adjusts the opening sequence of the flow distribution valve group according to the real-time monitored melt pressure and flow parameters, realizing rapid and seamless switching between products of different specifications. This solves the contradiction between system complexity and flexibility caused by the reliance on physical redundancy in traditional equipment.

[0056] The heat flow co-forming unit of this invention monitors the mold expansion and cooling contraction process in real time through laser displacement sensing and infrared thermal imaging technology, establishes a precise mapping relationship between cooling wind speed field, vacuum adsorption pressure and product deformation, and dynamically adjusts the forming parameters based on a multi-physics coupling model, thereby achieving closed-loop precise control of product wall thickness uniformity and dimensional stability, and significantly improving the product's mechanical properties and appearance quality. Attached Figure Description

[0057] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0058] Figure 1 This is an overall structural diagram of the continuous extruder used for producing plastic hollow boards according to the present invention.

[0059] Figure 2 This is a schematic diagram showing the structural connection between the integrated melt control system and the dynamically adjustable flow distribution mechanism of the present invention.

[0060] Figure 3This is a schematic diagram of the layout of the thermal-fluid co-forming unit and the online detection module of the present invention.

[0061] Figure 4 This is a flowchart of the continuous extruder operation method described in this invention.

[0062] Figure label:

[0063] 1-Main feeding system, 2-High shear twin-screw extruder, 3-Integrated melt control system, 4-Ultrasonic homogenizing unit, 5-Magnetorheological mixing unit, 6-Dynamic temperature compensation module, 7-Dynamically adjustable flow distribution mechanism, 8-Flow distribution valve group, 9-Branch pipeline, 10-Pressure-flow monitoring unit, 11-Forming die, 12-Machine vision system, 13-Central control unit, 14-Traction device, 15-Thermal-fluid coordinated shaping unit, 16-Shaping sleeve, 17-Cooling air box, 18-Vacuum adsorption system, 19-Online detection module, 20-Laser displacement sensor, 21-Infrared thermal imager. Detailed Implementation

[0064] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0065] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0066] Example 1: See Figures 1-4 This embodiment discloses a continuous extruder for producing plastic hollow boards, which is completed by the main feeding system 1, the high-shear twin-screw extruder 2, the integrated melt control system 3, the dynamically adjustable flow distribution mechanism 7, the forming die head 11, the heat-flow co-forming unit 15, the online detection module 19 and the central control unit 13. High-speed data interaction and real-time control are achieved through industrial Ethernet.

[0067] The continuous extruder operation method includes the following steps:

[0068] Multiple polymer raw materials and functional additives are fed into the main feeding system 1 according to a preset ratio. After plasticizing and primary mixing by the high-shear twin-screw extruder 2, a preliminary homogeneous melt is formed. The melt is transported to the integrated melt control system 3 through a metal hose. Inside the system, it undergoes ultrasonic-assisted re-homogenization, magnetorheological shear-enhanced mixing, and dynamic temperature compensation treatment based on melt viscoelastic feedback.

[0069] Then it enters the dynamically adjustable flow distribution mechanism 7. According to the target product specification instructions, the central control unit 13 drives the flow distribution valve group 8 to execute a predetermined opening and closing sequence, and distributes the homogeneous melt to the corresponding forming die head 11 according to the set flow ratio.

[0070] After the melt is extruded through the die head, it enters the heat-fluid co-forming unit 15. The heat-fluid co-forming unit 15 dynamically adjusts the cooling wind speed field and vacuum adsorption pressure gradient based on the real-time collected data on the expansion after demolding and the surface temperature distribution, and finally forms a finished plastic hollow board with stable dimensions and uniform wall thickness, thus completing continuous production.

[0071] The main feeding system 1 includes two loss-in-weight metering feeders, used for independent feeding of the main matrix resin and high-concentration functional masterbatch, respectively. Each feeder is equipped with a closed-loop weight feedback controller with a sampling frequency of 100Hz and a control accuracy of ±0.3%. The feeder outlet is connected to the side feed port of the twin-screw extruder via a rigid flange, ensuring that the material is pre-mixed before entering the screw compression section.

[0072] The main matrix resin is a polypropylene (PP) homopolymer with a density of 0.91 g / cm³, a melting point of 165℃, and a melt flow rate (MFR) of 3.0 g / 10 min (230℃ / 2.16 kg). The functional masterbatch consists of a matrix resin carrier (72.2 wt%, consistent with the main matrix resin as a polypropylene homopolymer), decabromodiphenyl ethane flame retardant (15 wt%), silver-loaded zirconium phosphate antibacterial agent (2 wt%), benzotriazole UV stabilizer (0.8 wt%), maleic anhydride-grafted polyolefin elastomer toughening agent (8 wt%), and magnetite magnetic nanoparticles (2 wt%). All additives are premixed for 30 minutes in a high-speed mixer at 1200 rpm before being added to the feeding system, with a mixing uniformity variation coefficient of less than 3%. During the feeding process, the main resin feeding rate is 180 kg / h, the functional masterbatch feeding rate is 24 kg / h, and the total feeding rate is 204 kg / h.

[0073] The high-shear twin-screw extruder 2 adopts a co-rotating parallel twin-screw structure with a total screw length-to-diameter ratio of 36:1. Based on the total length of each section of 648mm and the screw diameter of 18mm, it is divided into five functional sections.

[0074] The first section is the conveyor section, with a length of 108mm and a screw groove depth of 4.5mm;

[0075] The second section is the compression section, which is 144mm long. The screw groove depth gradually decreases from 4.5mm to 2.5mm to achieve material compaction and degassing.

[0076] The third section is the melting section, which is 144mm long and equipped with a kneading disc assembly. The discs are 5mm thick and staggered at a 30° angle. This assembly is used to break up solid particles and promote melting.

[0077] The fourth section is the primary mixing section, which is 144mm long and is equipped with a reverse thread element with a lead of 24mm, used to establish back pressure and enhance shear dispersion.

[0078] The fifth section is the homogenization section, which is 108mm long and equipped with a single-threaded element with a lead of 36mm, used to stabilize the output of homogeneous melt.

[0079] The screw is driven by an AC servo motor with a speed set at 180 rpm and a control accuracy of ±1 rpm. The barrel is externally equipped with segmented electric heating coils and an annular water-cooling channel, comprising five temperature control zones, each 120 mm in length. The temperature settings are: Zone 1 160℃, Zone 2 180℃, Zone 3 200℃, Zone 4 210℃, and Zone 5 205℃, with a temperature control accuracy of ±0.5℃. The melt pressure at the extruder outlet is 18.5 MPa, and the temperature is 203℃.

[0080] The integrated melt control system 3 is located downstream of the twin-screw extruder outlet and connected via a 316L stainless steel flexible hose with an inner diameter of 60mm and a wall thickness of 8mm. The inner wall of the melt pipeline is mirror-polished with a surface roughness Ra≤0.4μm, and is externally wrapped with a constant-power electric heating tape to maintain the basic conveying temperature at 200℃±2℃. The ultrasonic homogenizing unit 4 is installed in the middle of the melt pipeline and contains four circumferentially distributed piezoelectric ceramic transducers with a central excitation frequency of 28kHz and a maximum output sound intensity of 15W / cm². The transducers are coupled to the pipeline via titanium alloy amplitude transformers, the end of which extends 2mm into the pipeline to form a standing wave field with an axial coverage length of 150mm. The ultrasonic excitation operates in pulse mode with a duty cycle of 60%, applying high-frequency mechanical vibration to the melt to break up incompletely dispersed agglomerated particles and promote the deentanglement of molecular chains.

[0081] The magnetorheological hybridization unit 5 is located 500 mm downstream of the ultrasonic homogenization unit 4 and includes a ring-shaped electromagnetic coil, magnetic pole shoes, and a magnetic field control power supply. The electromagnetic coil is wound around the outer circumference of the pipe with 1200 turns, using copper-clad aluminum wire with a cross-sectional area of ​​6 mm² and insulation class H. The magnetic pole shoes are made of electrical pure iron with a relative permeability μr ≥ 4000, and eight pole shoes are symmetrically distributed along the circumference, with a 3 mm distance between their end faces and the outer wall of the pipe, forming a closed magnetic circuit. The magnetic field control power supply outputs a DC current of 12 A with a response time of less than 50 ms, generating a radial gradient magnetic field with a maximum magnetic induction intensity of 0.8 T inside the pipe. When the functional additive containing silver-loaded zirconium phosphate passes through this area, the magnetic nanoparticles form a chain structure under the action of the magnetic field, significantly enhancing the interfacial shear stress and achieving micron-scale dispersion reinforcement.

[0082] The magnetorheological mixing unit is activated only when the functional masterbatch or raw material contains magnetic nanoparticles; for formulations without magnetic components, this unit can be turned off, and mixing enhancement can be achieved solely through the ultrasonic homogenization unit.

[0083] The dynamic temperature compensation module 6 is located 300mm downstream of the magnetorheological mixing unit 5 to eliminate radial and axial temperature fluctuations of the melt during transport. The dynamic temperature compensation module 6 includes a distributed temperature sensor array, an infrared thermal imager, and a rapid heating / cooling actuator. The temperature sensor array consists of six platinum resistance temperature probes, equidistantly arranged along the circumference of the pipe. The probe insertion depth is 5mm, the sampling period is 100ms, and the measurement accuracy is ±0.3℃, used for real-time monitoring of the radial temperature distribution of the melt. The infrared thermal imager is installed directly above the pipe with a field of view of 45°, a spatial resolution of 0.5mm / pixel, and a frame rate of 60fps, used to capture axial temperature fluctuations on the melt surface.

[0084] The rapid heating / cooling actuator consists of an embedded ceramic heating element and a micro-nozzle array. The ceramic heating element has a power density of 15 W / cm² and a response time of less than 1 s; the micro-nozzle has an orifice diameter of 0.8 mm and an adjustable airflow velocity range of 5 m / s to 30 m / s. The central control unit 13 dynamically adjusts the heating power or cooling gas flow rate based on the temperature deviation signal using a PID control algorithm (proportional gain Kp = 2.5, integral time Ti = 10 s, derivative time Td = 1 s). After compensation, the temperature standard deviation of the melt before entering the distribution mechanism is controlled within ±0.8℃, and the maximum temperature difference does not exceed 1.6℃.

[0085] The dynamically adjustable flow distribution mechanism 7 includes a main pipeline, a flow distribution valve group 8, four branch pipelines 9, and a pressure-flow monitoring unit 10. The main pipeline is connected to the outlet of the integrated melt control system 3 via a flange with an inner diameter of 60 mm. The four branch pipelines 9 correspond to the forming dies 11 of four standard specifications of hollow plates, with inner diameters of 60 mm, 50 mm, 40 mm, and 35 mm, respectively, to match the die requirements of different cross-sectional areas. Each branch pipeline 9 inlet is equipped with an electric proportional ball valve. The valve core is made of silicon nitride ceramic with a hardness of HRA≥90, and the sealing ring is made of perfluoroether rubber with a temperature resistance rating of 300℃. The valve is driven by a stepper motor with a step angle of 1.8°, equipped with an absolute encoder, an angular displacement resolution of 0.018°, and an opening adjustment accuracy of ±0.5%. The pressure-flow monitoring unit 10 includes a differential pressure sensor and a Coriolis mass flow meter. The differential pressure sensor has a range of 0 MPa to 10 MPa and an accuracy class of 0.25%. It is installed before and after the inlet of each branch pipe (9) to measure the pressure drop before and after the valve. The mass flow meter has a range of 0 kg / h to 2000 kg / h and an accuracy of ±0.1%. It is used to obtain the melt mass flow rate of each branch in real time. All sensor data are uploaded to the central control unit (13) at 10 ms intervals.

[0086] The central control unit 13 executes the flow distribution logic control program based on preset product specification instructions. The specification matching subroutine calls the corresponding flow distribution valve opening and closing combination matrix according to the product code input by the operator. For example, when producing specification A (plate thickness 6mm, width 1200mm), only the first branch valve is opened and the other three are closed; when producing a combination of specification B (plate thickness 8mm) and specification C (plate thickness 10mm), the second and third branch valves are opened simultaneously, and the flow is distributed according to a mass ratio of 7:3, with the set flow rates being 142.8kg / h and 61.2kg / h, respectively. The flow balancing subroutine, based on the mass flow meter feedback value, adopts a feedforward-feedback composite control strategy, using the actual flow rate of the previous extrusion cycle as the feedforward reference and combining it with the current deviation for proportional adjustment, ensuring that the deviation between the actual flow rate of each activated branch and the set value is less than ±1.2%. The fault self-diagnosis subroutine continuously monitors the position feedback, pressure changes, and abnormal flow fluctuations of each valve. When it detects that the flow rate of a certain branch is lower than 80% of the set value and the duration exceeds 3 seconds, it is determined to be a blockage risk and automatically triggers the reverse flushing program of that branch, that is, briefly opening the reverse pneumatic valve to introduce compressed air at a pressure of 0.6MPa for reverse purging for a duration of 2 seconds.

[0087] The forming die head 11 includes a die body, a flow divider, a die plate, and an adjustment mechanism. The die body is made of H13 hot work die steel, quenched and tempered to a hardness of 48HRC to 52HRC. A spiral flow divider channel is set inside the die body, with an Archimedean spiral cross-section, a starting radius of 30mm, an ending radius of 80mm, a pitch of 100mm, and two and a half turns, ensuring uniform circumferential distribution of the melt before entering the die plate. The flow divider is fixed at the center of the die body, with a streamlined spindle shape, a front arc radius of 25mm, a rear cone angle of 15°, and a 25μm thick CrN coating with a friction coefficient μ≤0.15. The die plate is detachably installed at the front end of the die body and secured with eight M16 socket head cap screws with a preload torque of 120N·m. The die plate has a core mold and an outer mold corresponding to the target hollow plate structure, forming an annular extrusion gap between them. The current production specification is a double-walled honeycomb hollow board with an overall thickness of 8mm and an extrusion gap width set at 2.5mm. It is adjusted by a 0.5mm precision shim made of stainless steel with a surface flatness better than 0.01mm.

[0088] The heat-flow co-forming unit 15 includes a forming sleeve 16, a cooling air box 17, a vacuum adsorption system 18, and an online detection module 19. The forming sleeve 16 is made of aluminum alloy and has an internally machined forming cavity that matches the outer contour of the hollow plate. The cavity is 1200mm long and divided into three temperature zones, each with independent temperature control. The first temperature zone is set at 85℃, the second at 65℃, and the third at 45℃. Temperature control is achieved through internal circulation of heat transfer oil, with an oil temperature control accuracy of ±1℃. The cooling air box 17 is located at the outlet end of the forming sleeve 16 and includes upper and lower sets of air knives. The air knife slit width is 1.0mm, the adjustable air pressure range is 1.5kPa to 6.0kPa, and the wind speed distribution uniformity error is less than ±5%. The air source is a centrifugal fan with an air volume of 8000m³ / h, which is treated by an air filter (ISO 8573-1 Class 2) before being sent to the air knives. The vacuum adsorption system 18 consists of a vacuum pump, a distribution valve, and an adsorption pore array. The vacuum pump has a maximum pressure of 100 Pa and a pumping speed of 120 L / s. The adsorption pores are distributed on the inner wall of the shaping sleeve 16, with a pore diameter of 1.2 mm and a pore spacing of 20 mm × 20 mm, arranged in a square array. The vacuum level is set to -60 kPa. The surface of the cavity of the shaping sleeve 16 is coated with a polytetrafluoroethylene (PTFE) coating with a thickness of 30 μm and a surface energy of less than 25 dyn / cm, effectively reducing frictional resistance.

[0089] The online inspection module 19 includes laser displacement sensors 20, an infrared thermal imager 21, and a machine vision system 12. Four laser displacement sensors 20 are arranged at the top, bottom, left, and right positions of the hollow board's cross-section, with a measurement range of 0mm to 50mm, a resolution of 1μm, and a sampling frequency of 1kHz, used to acquire wall thickness data in real time. The infrared thermal imager 21 monitors the surface temperature field of the hollow board at a frame rate of 30fps and a temperature resolution of 0.1℃. The machine vision system 12 includes a line scan camera and an LED backlight. The camera resolution is 4096 pixels, and the scanning frequency is 20kHz, used to identify surface defects such as fisheyes, scratches, or color differences. All inspection data is transmitted to the central control unit 13 at 100ms intervals.

[0090] The central control unit 13 executes a heat-fluid coordinated control algorithm based on the wall thickness deviation and surface temperature gradient fed back by the online detection module 19. When the wall thickness on a certain side exceeds the tolerance zone (±0.1mm), the system automatically adjusts the cooling air knife pressure on the corresponding side to increase the cooling intensity and suppress mold expansion. The adjustment step is 0.2kPa, and the maximum adjustment range is ±1.5kPa. When the surface temperature difference exceeds 5℃, the heat transfer oil flow regulating valve is activated to change the heating / cooling power of the corresponding temperature zone, so that the temperature gradient is restored to within 2℃. When the machine vision system 12 detects the same type of defect for three consecutive cycles, the system records the defect location and process parameter combination, and generates an early warning signal to prompt the operator to check the raw material batch or mold cleanliness status.

[0091] The quick mold change mechanism automates the replacement of the die template through a standardized interface. This standardized interface includes a locating pin, a hydraulic clamping cylinder, and an electrical connector. The locating pin has a diameter of 20mm and a tolerance grade of H7 / g6, ensuring a repeatability of less than 0.02mm. The hydraulic clamping cylinder operates at a pressure of 10MPa, with a clamping force of 40kN and an actuation time of less than 8s. The electrical connector transmits signals between the heating rod and the thermocouple, with a mating life greater than 100,000 cycles. The replacement process is performed by a robotic arm, which retrieves the target die template from the die library, aligns it with the locating pin, inserts it, initiates hydraulic clamping, and completes the electrical connection. The entire process takes no more than 85 seconds. During this time, the main extrusion system maintains a low speed (50rpm), and the melt circulates within the main pipeline with the diversion valve closed to prevent degradation during downtime.

[0092] The melt residence time optimization strategy is achieved by adjusting the synergistic relationship between the twin-screw extruder speed, the diverter valve opening, and the molding traction speed. Under the current operating conditions, with a screw speed of 180 rpm, a traction speed of 6.2 m / min, and a diverter valve opening of 100%, the calculated total residence time of the melt from the feed to the extruder outlet is 203 s, which is within a reasonable range of 180 s to 240 s. For heat-sensitive materials such as polyvinyl chloride (PVC), the system automatically sets the upper limit of the residence time to 210 s to prevent thermal degradation.

[0093] The energy consumption monitoring and optimization module integrates an electricity meter, flow meter, and temperature sensor to collect real-time energy consumption data from the main motor, heating system, and cooling system. The current unit product energy consumption index is 0.86 kWh / kg. When this index exceeds the benchmark value by 10% for five consecutive batches, the system automatically initiates an energy efficiency diagnostic program to analyze whether there are problems such as overheating in the heating zone, excessive cooling water flow, or abnormal screw back pressure, and recommends parameter adjustment solutions.

[0094] Abnormal operating condition response mechanisms include:

[0095] When the melt pressure rises sharply by more than 20% above the set value, the system automatically starts the pressure relief procedure, opens the bypass valve to guide part of the melt into the recovery tank, and reduces the screw speed by 10%. When the cooling water temperature is 5°C higher than the set value, the standby cooling tower fan is started and an equipment maintenance reminder is issued. When the mismatch between the traction speed and the extrusion rate exceeds ±3%, the system suspends the diversion operation and prioritizes stable extrusion of a single path until the parameters are recalibrated.

[0096] The central control unit 13 hardware platform employs a dual-redundant PLC controller with a 1.2GHz CPU, 4GB of memory, and a real-time operating system. It features power-off retention and can store 1024 process recipes, each containing 215 parameters. All control signal transmission uses the industrial Ethernet protocol with a communication rate of 100Mbps. The network topology is a ring-redundant structure, supporting PROFINET IRT real-time communication with a data refresh cycle of 1ms and a synchronization error of less than 8μs. The system is equipped with a remote monitoring interface supporting 5G wireless communication, allowing technicians to access equipment status, modify parameters, and receive alarm information via an encrypted channel.

[0097] The traction device 14 adopts a dual-track structure, with the track surface covered with polyurethane material, a hardness of 85 Shore A, a traction roller diameter of 200mm, a traction force set at 12kN, and a speed control accuracy of ±0.1%. Abnormal melt collected in the recovery tank, after crushing, cleaning, and drying, can be reused as recycled material in the main feeding system 1, with the recycled material ratio controlled at 12%, without affecting the final product performance. All material contact parts comply with FDA 21 CFR 177.1520 and EU 10 / 2011 food contact material regulations. The overall equipment protection rating is IP54, and the noise level is 73.5dB(A), meeting the GB 5226.1-2019 mechanical and electrical safety standards. The entire line is equipped with an emergency stop button, safety light curtain, and interlocking devices to ensure operator safety.

[0098] In one specific embodiment, the method of the present invention is used to produce a polypropylene-based double-walled honeycomb hollow board with a thickness of 8 mm, a width of 1200 mm, and trapezoidal cross-sections for the supporting ribs, with an upper base width of 2 mm, a lower base width of 4 mm, a height of 6 mm, and a spacing of 20 mm. The process parameters are as follows: screw speed 180 rpm, zone temperatures 160 / 180 / 200 / 210 / 205℃, die extrusion temperature 202℃, three-zone temperatures of the shaping sleeve 16 85 / 65 / 45℃, cooling air pressure 3.2 kPa, vacuum degree -60 kPa, and traction speed 6.2 m / min. The resulting product has a wall thickness variation coefficient of 1.1%, a warpage deformation of 1.6 mm / m, a flexural modulus of 1620 MPa, and a drop hammer impact strength of 43 kJ / m².

[0099] Comparative Example 1: In Comparative Example 1, a traditional single-screw extruder was used with a static manifold and a fixed shaping device to produce products of the same specifications. Ultrasonic homogenization, magnetorheological mixing, and dynamic temperature compensation functions were not configured. The remaining processes were described as the same. The resulting product had a wall thickness variation coefficient of 3.4%, a warpage of 5.1 mm / m, a flexural modulus of 1510 MPa, and a drop hammer impact strength of 38 kJ / m².

[0100] The product performance of Example 1 and Comparative Example 1 is shown in Table 1:

[0101] Table 1:

[0102]

[0103] Existing technologies primarily rely on the macroscopic mechanical shearing of screws, whose mixing intensity and uniformity are limited by the screw's geometry and aspect ratio, thus having a physical upper limit. This invention utilizes high-frequency mechanical vibration to generate cavitation, disrupting van der Waals forces between aggregates at the molecular scale and achieving initial de-agglomeration. The magnetorheological mixing unit then uses a gradient magnetic field to manipulate magnetic nanoparticles into dynamic chain structures, constructing countless micrometer-scale instantaneous high-shear fields within the melt. These shear rates far exceed those of traditional screw shearing, thereby achieving ultimate dispersion of functional additives, especially nanoscale particles. The continuous spatiotemporal interaction of these two technologies overcomes the fundamental limitations of single screw shearing in terms of diffusion rate and scale of action.

[0104] This invention uses the viscoelasticity of the melt, a core rheological parameter that directly determines molding quality, as a feedback variable. Its dynamic changes are captured in real time through a distributed sensor network, and a rapid actuator is used for proactive compensation. This ensures that the melt maintains a highly consistent rheological state before entering the molding stage, fundamentally suppressing defects such as uneven expansion after mold release and warping caused by fluctuations in inlet conditions, thus achieving closed-loop precise control of molding accuracy.

[0105] This invention utilizes a feedforward-feedback composite control algorithm to sense and dynamically match the flow resistance characteristics of each branch in real time, achieving precise on-demand allocation of melt flow. It enables rapid and seamless switching between multiple product specifications, resolving the inherent contradiction between system complexity and production flexibility caused by traditional equipment's physical redundancy-based production changeover.

[0106] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous extruder for producing plastic hollow boards, characterized in that, include: The main feeding system, high-shear twin-screw extruder, integrated melt control system, dynamically adjustable flow distribution mechanism, forming die and heat-fluid co-forming unit, as well as central control unit and flow distribution valve group are connected in sequence. The continuous extruder operation method includes the following steps: Multiple polymer raw materials and functional additives are fed into the main feeding system according to a preset ratio, and then plasticized and primary mixed by a high-shear twin-screw extruder. The resulting melt is then transported to an integrated melt control system. Within the integrated melt control system, the melt undergoes ultrasonic-assisted rehomogenization, magnetorheological shear-enhanced mixing, and dynamic temperature compensation based on melt viscoelastic feedback. Then it enters the dynamic adjustable flow distribution mechanism. According to the target product specification instructions, the central control unit drives the flow distribution valve group to execute a predetermined opening and closing sequence, and distributes the homogeneous melt to the corresponding forming die head according to the set flow ratio. After the melt is extruded through the die head, it enters the heat-fluid co-forming unit; the heat-fluid co-forming unit dynamically adjusts the cooling wind speed field and vacuum adsorption pressure gradient based on the real-time collected data on the expansion after demolding and the surface temperature distribution. The final product is a dimensionally stable, uniformly thick plastic hollow board, thus completing continuous production.

2. The continuous extruder for producing plastic hollow boards according to claim 1, characterized in that: The main feeding system includes at least two loss-in-weight metering feeders, which are used for independent feeding of the main matrix resin and high-concentration functional masterbatch, respectively. Each feeder is equipped with a closed-loop weight feedback controller. The feeder outlet is connected to the side feed port of the twin-screw extruder through a rigid flange to ensure that the material is pre-mixed before entering the screw compression section.

3. The continuous extruder for producing plastic hollow boards according to claim 2, characterized in that: The high-shear twin-screw extruder adopts a co-rotating parallel twin-screw structure with a total screw length-to-diameter ratio of 36:1, and is divided into five functional sections: The first section is the conveying section, with a screw groove depth of 4.5mm; The second section is the compression section, where the screw groove depth gradually decreases from 4.5mm to 2.5mm; The third section is the melting section, equipped with kneading discs, with a disc thickness of 5mm and a staggered angle of 30°; The fourth section is the primary mixing section, equipped with a reverse thread element with a lead of 24mm; The fifth section is the homogenization section, equipped with a single-headed threaded element with a lead of 36mm. The screw speed is driven by an AC servo motor, with an adjustment range of 50rpm-300rpm and a speed control accuracy of ±1rpm. The barrel is equipped with a segmented electric heating coil and an annular water cooling channel, with a temperature control range of 160℃-220℃ and a temperature control accuracy of ±0.5℃.

4. The continuous extruder for producing plastic hollow boards according to claim 1, characterized in that: The integrated melt control system includes a melt pipeline, an ultrasonic homogenizing unit, a magnetorheological mixing unit, and a dynamic temperature compensation module. The melt pipeline is made of stainless steel, and the inner wall of the pipeline is mirror polished with a surface roughness Ra≤0.4μm. A constant power electric heating tape is wrapped around the outside of the pipeline to maintain the basic conveying temperature at 200℃±2℃.

5. A continuous extruder for producing plastic hollow boards according to claim 4, characterized in that: The ultrasonic homogenizing unit is installed in the middle of the melt pipe and includes four circumferentially distributed piezoelectric ceramic transducers. The transducers are coupled to the inner wall of the pipe through titanium alloy amplitude transformers. The end of the amplitude transformer extends into the inside of the pipe to form a standing wave field action area. The standing wave field covers a length of 150 mm along the axial direction and is used to apply high-frequency mechanical vibration to the melt, break up agglomerated particles and promote the deentanglement of molecular chains.

6. The continuous extruder for producing plastic hollow boards according to claim 4, characterized in that: The magnetorheological mixing unit is located downstream of the ultrasonic homogenizing unit and includes a ring-shaped electromagnetic coil, magnetic pole shoes, and a magnetic field control power supply. The electromagnetic coil is wound around the outer circumference of the melt pipe, using copper-clad aluminum wire with a cross-sectional area of ​​6 mm² and an insulation class of H. The magnetic pole shoes are made of electrical pure iron with a relative permeability μr ≥ 4000. Eight symmetrically distributed pole shoes are arranged along the circumference of the pipe, with a distance of 3 mm between the end face of the pole shoes and the outer wall of the pipe, forming a closed magnetic circuit. The magnetic field control power supply outputs a DC current ranging from 0A to 20A with a response time of less than 50ms. It can generate a radial gradient magnetic field with a maximum magnetic induction intensity of 0.8T inside the pipe. The pipe section covered by the gradient magnetic field constitutes the magnetic field action zone. When the functional additive containing magnetic nanoparticles passes through the magnetic field action zone with the melt, the particles form a chain structure under the action of the magnetic field, enhancing the interfacial shear stress and achieving micron-scale dispersion reinforcement.

7. A continuous extruder for producing plastic hollow boards according to claim 4, characterized in that: The dynamic temperature compensation module is located downstream of the magnetorheological hybrid unit and includes a distributed temperature sensor array, an infrared thermal imager, and a rapid heating / cooling actuator. The temperature sensor array consists of six platinum resistance temperature probes, which are equidistantly arranged along the circumference of the pipe. The probe insertion depth is 5 mm, the sampling period is 100 ms, and the measurement accuracy is ±0.3℃. The infrared thermal imager is installed directly above the pipe, with a field of view of 45°. The rapid heating / cooling actuator consists of an embedded ceramic heating element and a micro-nozzle array. The airflow speed is adjustable from 5 m / s to 30 m / s. The central control unit uses a PID control algorithm based on the temperature deviation signal. It takes the temperature deviation signal collected by the temperature sensor array and the infrared thermal imager as input, and the heating power adjustment signal and the cooling gas flow rate adjustment signal as output to dynamically control the melt temperature, so that the temperature standard deviation of the melt before entering the distribution mechanism is controlled within ±1.0℃.

8. A continuous extruder for producing plastic hollow boards according to claim 1, characterized in that, The dynamically adjustable diversion and distribution mechanism includes a main pipeline, a diversion valve group, branch pipelines, and a pressure-flow monitoring unit. The main pipeline is connected to the outlet flange of the integrated melt control system. There are four branch pipelines, each corresponding to a molding die head for a standard specification of hollow plate. Each branch pipeline inlet is equipped with an electric proportional ball valve with a silicon nitride ceramic core and a perfluoroether rubber sealing ring. The valve is driven by a stepper motor and equipped with an absolute encoder, with an opening adjustment accuracy of ±0.5%.

9. A continuous extruder for producing plastic hollow boards according to claim 1, characterized in that, The heat-fluid coordinated shaping unit includes a shaping sleeve, a cooling air box, a vacuum adsorption system, and an online detection module. The shaping sleeve cavity is 1200mm long and divided into three temperature zones, each with independent temperature control. The first temperature zone is set to 85℃, the second to 65℃, and the third to 45℃. The temperature control method is internal flow channel circulation of heat transfer oil. The cooling air box includes upper and lower sets of air knives with a slit width of 1.0mm and an adjustable air pressure range of 1.5kPa to 6.0kPa. The adsorption holes of the vacuum adsorption system are distributed on the inner wall of the shaping sleeve, with a hole spacing of 20mm×20mm, arranged in a square array, and the vacuum degree is set to -60kPa.

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