Extrusion screw current monitoring closed loop control apparatus and control method

Abstract

This invention discloses a closed-loop control device and method for extrusion screw current monitoring, relating to the field of extrusion screw technology. It includes a base mounting frame and a support frame. A screw current monitoring module is mounted on the base mounting frame. The screw current monitoring module includes a drive module, a drive rod, a drive screw, and a sensing module. The drive module contains a servo motor, the output end of which is fixedly connected to the drive rod. The end of the drive rod furthest from the servo motor is fixedly connected to the drive screw. The sensing module is located on the outside of the drive screw. A guide rod is fixedly connected between the base mounting frame and the support frame. A movable extrusion assembly is jointly provided between the drive screw and the guide rod. The movable extrusion assembly includes a hollow sleeve fixedly connected to the support frame, and an extrusion rod fixedly connected to the moving screw nut seat. The size of the extrusion rod is adapted to the size of the hollow sleeve. An adjustment module is mounted on the outside of the drive module, and an electrical connection module is mounted on the outside of the base mounting frame.

Description

Technical Field

[0001] This invention relates to the field of extrusion screw technology, and in particular to a closed-loop control device and control method for extrusion screw current monitoring. Background Technology

[0002] Screw extrusion is a core molding process in the production of rubber and plastic products, medical precision tubing, high-end industrial profiles, and modified composite materials. It is widely used in many core sectors of the national economy, such as automobile manufacturing, medical devices, consumer electronics, and packaging and building materials. With the upgrading of downstream industries towards high-end products, large-scale continuous production has become the industry mainstream. The industry's demand for the controllability of extrusion processes, the reproducibility of processes, and the intelligent management and control capabilities of production processes continues to increase. Precision control technology for extrusion processes that is compatible with the high-quality development of the industry has become an important research and development and industrial application direction in this field.

[0003] Traditional extrusion equipment often operates at a preset fixed speed, making it difficult to detect fluctuations in the melt viscosity of materials, uneven feeding, and changes in screw load caused by slight wear of the equipment. This can easily lead to problems such as fluctuations in extrusion volume, out-of-tolerance product dimensions, and material degradation due to shearing and overheating. Frequent manual inspections and adjustments are required, which not only increases labor costs but also produces a large number of defective products. In particular, it has poor adaptability to heat-sensitive and highly filled materials. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies, such as the inability to detect fluctuations in material melt viscosity, uneven feeding, and changes in screw load caused by slight wear of the equipment, which can easily lead to fluctuations in extrusion volume, out-of-tolerance product dimensions, and material degradation due to shearing and overheating. The invention proposes a closed-loop control device and method for extrusion screw current monitoring.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An extrusion screw current monitoring closed-loop control device includes a base mounting frame and a support frame. A screw current monitoring module is disposed on the base mounting frame. The screw current monitoring module includes a drive module, a drive rod, a drive screw, and a sensing module. The drive module includes a servo motor. The output end of the servo motor is fixedly connected to the drive rod. The end of the drive rod away from the servo motor is fixedly connected to the drive screw. The sensing module is disposed on the outside of the drive screw. A guide rod is fixedly connected between the base mounting frame and the support frame. A movable extrusion assembly is provided between the drive screw and the guide rod. The movable extrusion assembly includes a hollow sleeve fixedly connected to the support frame and a nut movable seat threadedly connected to the drive screw. An extrusion rod is fixedly connected to the nut movable seat. The size of the extrusion rod is adapted to the size of the hollow sleeve. An adjustment module is mounted on the outside of the drive module, and an electrical connection module is mounted on the outside of the base mounting bracket.

[0006] The above technical solution further includes: Specifically, the drive module also includes a servo driver that is matched with the servo motor, and the sensing module is a Hall current sensor; The Hall current sensor is installed on the power supply circuit between the output side of the servo driver and the servo motor, and is used to collect the operating current signal of the servo motor.

[0007] Specifically, a guide slide is symmetrically fixedly connected to the outer side of the nut moving seat, the guide slide and the guide rod are slidably connected, and an annular bracket is fixedly connected to the upper part of the bearing frame, and the inner side of the annular bracket and the hollow sleeve are fixedly connected.

[0008] Specifically, the upper part of the base mounting bracket is fixedly connected to the electrical connection module, which includes a terminal block, a signal filtering unit, a power supply interface, and a communication interface, used to realize signal transmission, electrical isolation, and power distribution between the sensing module, the control module, and the drive module; The control module includes a controller body, a parameter storage unit, a control calculation unit, and a communication unit. The control calculation unit has a built-in PID control program and an overload protection program, which are used to perform speed regulation and abnormal protection actions. The parameter storage unit is used to store pre-calibrated process parameters.

[0009] A closed-loop control method for extrusion screw current monitoring, applied to the aforementioned closed-loop control device for extrusion screw current monitoring, includes the following steps: S1. Pre-calibration determines the target current threshold, allowable deviation range, and overload protection threshold of the drive module corresponding to the target extrusion process; S2. Start the drive module, drive the drive screw to rotate through the drive rod, drive the nut moving seat and the extrusion rod to move along the guide rod, and cooperate with the hollow sleeve to perform the extrusion operation; S3. The operating current signal of the drive module is collected in real time through the sensing module and transmitted to the control module through the electrical connection module; S4. The control module compares the real-time operating current with the preset target current threshold and calculates the current deviation. S5. The control module adjusts the output speed of the drive module according to the current deviation to stabilize the working current within the allowable deviation range, thus completing closed-loop control.

[0010] Specifically, the pre-calibration of step S1 is as follows: determine the material, product specifications, and process temperature parameters corresponding to the target working condition; collect multiple sets of steady-state current and actual extrusion volume data of the drive module under standard process conditions; fit the relationship between current and extrusion volume; and determine the target current threshold, allowable deviation range, and overload protection threshold.

[0011] Specifically, the speed adjustment in step S5 is as follows: when the real-time operating current is greater than the upper limit of the target current threshold, the control module reduces the output speed of the servo motor; when the real-time operating current is less than the lower limit of the target current threshold, the control module increases the output speed of the servo motor.

[0012] Specifically, it also includes safety protection steps: when the control module detects that the real-time operating current exceeds the overload protection threshold, it generates a speed reduction, alarm, or shutdown command and sends it to the drive module for execution.

[0013] Specifically, it also includes a linkage control step: the control module sends adjustment commands to the corresponding feeding mechanism and traction mechanism in sync with the current change of the drive module to achieve coordinated adjustment of parameters across the entire line.

[0014] Specifically, it also includes data recording steps: the control module records the current, speed, and process parameter data of the entire extrusion process.

[0015] The present invention has the following beneficial effects: In this invention, the servo motor operating current of the drive module is collected in real time by the sensing module, and the real-time load status of the screw is fed back. The closed-loop speed dynamic adjustment is completed by the control module, which can offset the load deviation caused by fluctuations in material melting characteristics, slight wear of equipment, and changes in working conditions in real time. This ensures that the extrusion feed speed always matches the optimal load range set by the process, effectively avoiding common problems such as extrusion volume fluctuations, product size deviations, and material shear overheating, and significantly reducing the product defect rate. At the same time, there is no need to add complex melt pressure detection components, so as to achieve precise and controllable extrusion process at low cost and adapt to stable extrusion production of multiple types of materials. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the extrusion screw current monitoring closed-loop control device proposed in this invention. Figure 2 This is a schematic side view of the overall structure of the extrusion screw current monitoring closed-loop control device in this invention; Figure 3 This is a cross-sectional view of the hollow sleeve in this invention. Figure 4 for Figure 1 Enlarged schematic diagram of the structure at point A in the middle; Figure 5A flowchart illustrating the steps of a closed-loop control method for monitoring extrusion screw current. Figure 6 A schematic diagram illustrating the operation of a closed-loop control method for monitoring extrusion screw current.

[0017] In the diagram: 1. Base mounting bracket; 2. Bearing frame; 3. Drive module; 301. Drive rod; 302. Drive screw; 4. Sensing module; 5. Screw nut moving seat; 501. Limit support seat; 6. Guide rod; 7. Extrusion rod; 8. Annular bracket; 801. Hollow sleeve; 9. Control module; 10. Electrical connection module. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0019] like Figures 1-6 As shown, the present invention proposes an extrusion screw current monitoring closed-loop control device, including a base mounting frame 1 and a support frame 2. The base mounting frame 1 is provided with a screw current monitoring module. The screw current monitoring module includes a drive module 3, a drive rod 301, a drive screw 302 and a sensing module 4. The drive module 3 includes a servo motor inside. The output end of the servo motor is fixedly connected to the drive rod 301. The end of the drive rod 301 away from the servo motor is fixedly connected to the drive screw 302. The sensing module 4 is located on the outside of the drive screw 302. A guide rod 6 is fixedly connected between the base mounting frame 1 and the support frame 2. A movable extrusion assembly is provided between the drive screw 302 and the guide rod 6. The movable extrusion assembly includes a hollow sleeve 801 fixedly connected to the support frame 2 and a nut moving seat 5 threadedly connected to the drive screw 302. An extrusion rod 7 is fixedly connected to the nut moving seat 5. The size of the extrusion rod 7 is adapted to the size of the hollow sleeve 801. An adjustment module 9 is installed on the outside of the drive module 3, and an electrical connection module 10 is installed on the outside of the base mounting bracket 1.

[0020] Furthermore, the base mounting frame 1 and the support frame 2 provide stable installation support and positioning reference for the power, transmission, detection, execution and control components of the whole device. Before operation, the control module 9 completes the parameter pre-calibration of the target extrusion process and stores the target current threshold, allowable deviation range and overload protection parameters of the drive module 3 under the corresponding working conditions. After the formal extrusion operation is started, the control module 9 sends an operation command to the drive module 3. The servo motor in the drive module 3 outputs rotational power, and the rotational torque is synchronously transmitted to the drive screw 302 through the drive rod 301. The drive screw 302 converts the rotational motion into the linear feeding action of the nut moving seat 5. The guide rod 6 provides precise guidance and constraint for the linear motion of the nut moving seat 5 to avoid radial movement during the feeding process. The nut moving seat 5 synchronously drives the extrusion rod 7 to perform linear feeding, so that the extrusion rod 7 cooperates with the hollow sleeve 801 fixed on the support frame 2 to complete the continuous extrusion operation of the material. During operation, the sensing module 4 collects the working current signal of the servo motor in the drive module 3 in real time. After the electrical connection module 10 completes signal filtering, format conversion and electrical isolation, the current signal is stably transmitted to the control module 9. The control module 9 compares the real-time collected working current signal with the pre-calibrated target current threshold, calculates the deviation between the two, and sends a speed adjustment command to the drive module 3 in real time to dynamically correct the output speed of the servo motor, so that the motor working current is always stable within the preset allowable deviation range. This offsets the extrusion deviation caused by material characteristic fluctuations, load changes, equipment wear and other interferences, and ensures the long-term stability of extrusion volume and plasticization state. Simultaneously, the control module 9 monitors abnormal current fluctuations and overload conditions in real time. Once the protection threshold is exceeded, it immediately triggers speed reduction, alarm, or shutdown protection actions to prevent equipment damage.

[0021] The drive module 3 also includes a servo driver that is compatible with the servo motor, and the sensing module 4 is a Hall current sensor; The Hall current sensor is installed on the power supply circuit between the servo driver output side and the servo motor to collect the operating current signal of the servo motor.

[0022] Furthermore, during the extrusion operation, the servo driver of the drive module 3 serves as the core drive execution unit of the servo motor. On the one hand, it receives the speed control command issued by the control module 9, converts the power frequency power into variable frequency drive power that matches the command requirements, controls the speed, direction and output torque of the servo motor, and provides stable and controllable power output for the extrusion feeding action. The Hall current sensor in the sensing module 4, installed on the output side of the servo driver and in the power supply circuit of the servo motor, collects the working current data of the three-phase power supply line of the servo motor in real time during motor operation. This current data directly corresponds to the real-time output torque of the servo motor and the screw load status. The Hall current sensor converts the collected current signal into a standard transmittable electrical signal, which is stably transmitted to the control module 9 through the electrical connection module 10, providing the core load feedback basis for the entire closed-loop control system.

[0023] The outer side of the nut moving seat 5 is symmetrically fixedly connected with a guide slide 501, the guide slide 501 and the guide rod 6 are slidably connected, and the upper part of the bearing frame 2 is fixedly connected with an annular bracket 8, the inner side of the annular bracket 8 and the hollow sleeve 801 are fixedly connected.

[0024] Furthermore, during the feeding process of the extrusion operation, the nut moving seat 5 receives the rotational power transmitted by the drive screw 302, converts the rotational motion into linear feed motion, and provides stable power transmission for the feeding action of the extrusion rod 7. Synchronously, the guide slides 501 symmetrically arranged on the outer side of the nut moving seat 5 slide synchronously along the guide rod 6. Through the sliding cooperation with the guide rod 6, the radial movement and circumferential deflection of the nut moving seat 5 during the feeding process are restricted, ensuring the straightness and smooth operation of the feeding action throughout the process, and avoiding the swaying and jamming problems when the extrusion rod 7 moves. The annular bracket 8 fixed on the support frame 2 provides stable radial and axial limiting support for the hollow sleeve 801, ensuring the coaxiality of the hollow sleeve 801 and the extrusion rod 7, so that the linear feeding action of the extrusion rod 7 can be precisely matched with the hollow sleeve 801 to stably complete the extrusion and conveying operation of materials.

[0025] The upper part of the base mounting bracket 1 is fixedly connected to the electrical connection module 10. The electrical connection module 10 includes a terminal block, a signal filtering unit, a power supply interface, and a communication interface, which are used to realize signal transmission, electrical isolation, and power distribution between the sensing module 4, the control module 9, and the drive module 3. The control module 9 includes a controller body, a parameter storage unit, a control calculation unit, and a communication unit. The control calculation unit has a built-in PID control program and an overload protection program, which are used to perform speed regulation and abnormal protection actions. The parameter storage unit is used to store pre-calibrated process parameters.

[0026] Furthermore, in the entire process of extrusion unit operation preparation, closed-loop operation and safety protection, the electrical connection module 10 fixed on the upper part of the base mounting frame 1 achieves reliable crimping of the electrical lines between the sensing module 4, the control module 9 and the drive module 3 through the built-in terminal block, avoiding the fault of loosening of the lines caused by equipment vibration at the production site. The power supply interface is used to allocate a suitable working power to each electrical module, especially to provide a stable low-voltage power supply to the sensing module 4, so as to ensure the continuous normal operation of the current acquisition element. A signal transmission channel is established between the modules through a communication interface to achieve stable uploading of acquired signals and the issuance of control commands; Meanwhile, the built-in signal filtering unit performs noise reduction processing on the original signal of motor operating current collected by the sensing module 4, filtering out electromagnetic interference in the workshop and signal noise caused by motor operation, so as to ensure that the current data transmitted to the control module 9 can accurately reflect the real operating status of the servo motor. The control module 9 takes the controller as the core to coordinate the control logic of the entire device. Before operation, the parameter storage unit pre-stores and retrieves the process parameters such as the target current threshold, allowable deviation range, and overload protection threshold that have been pre-calibrated for the corresponding material and product specifications, so that there is no need to repeat the calibration settings for each operation. During operation, the real-time current signal processed by the electrical connection module 10 is received through the communication unit and synchronously transmitted to the control and calculation unit. The control and calculation unit performs closed-loop calculation on the deviation between the real-time current and the preset target current through the built-in PID control program, generates a matching speed adjustment command, and then sends it to the drive module 3 through the communication unit and the electrical connection module 10 to correct the output speed of the servo motor in real time, so that the motor load current is always stable within the range of process requirements, ensuring the consistency between extrusion volume and product molding quality. Meanwhile, the control unit monitors the current status throughout the process through a built-in overload protection program. Once it detects abnormal conditions such as the current exceeding the overload protection threshold or excessive fluctuations in a short period of time, it immediately generates protection commands such as speed reduction, alarm, or emergency shutdown to prevent the servo motor from burning out due to overload and the extrusion mechanism from jamming and being damaged, thus ensuring the safety and stability of the equipment and the operation process.

[0027] A closed-loop control method for extrusion screw current monitoring, applied to an extrusion screw current monitoring closed-loop control device, includes the following steps: S1. Pre-calibrate to determine the target current threshold, allowable deviation range and overload protection threshold of the drive module 3 corresponding to the target extrusion process; S2. Start the drive module 3, drive the drive screw 302 to rotate through the drive rod 301, drive the screw nut moving seat 5 and the extrusion rod 7 to move along the guide rod 6, and cooperate with the hollow sleeve 801 to perform the extrusion operation. S3. The working current signal of the drive module 3 is collected in real time by the sensing module 4 and transmitted to the control module 9 via the electrical connection module 10. S4, the control module 9 compares the real-time operating current with the preset target current threshold and calculates the current deviation. S5, the control module 9 adjusts the output speed of the drive module 3 according to the current deviation, so that the working current is stabilized within the allowable deviation range, thus completing closed-loop control.

[0028] Furthermore, in the actual production implementation of this extrusion screw current monitoring closed-loop control method, the process pre-calibration work of step S1 is first completed through the control module 9. The operators combine the basic production parameters such as the melting characteristics of the target extruded material, product specifications and dimensions, and preset process temperature, and complete multiple trial productions under standard and stable process conditions. Simultaneously, the steady-state current of the drive module 3 under stable extrusion conditions, the corresponding actual extrusion amount, and the product forming quality data are collected and recorded. The correspondence between current and extrusion load and extrusion amount is established by fitting. Finally, the target current threshold of the drive module 3 corresponding to the target extrusion process, the allowable deviation range of normal production, and the overload protection threshold of equipment safety are determined and stored in the control module 9, providing a benchmark for subsequent closed-loop control. The target current threshold and overload protection threshold are determined by the control module 9, sensing module 4, and drive module 3 of this device, combined with production process requirements and equipment hardware safety boundaries, through a standardized pre-calibration process. The target current threshold prioritizes ensuring stable extrusion quality. First, fixed process parameters such as the target material grade and melt characteristics, process temperatures of each section of the barrel, die specifications, and target extrusion volume are locked. Under baseline conditions completely consistent with subsequent formal production, 3-5 sets of continuous steady-state trial production are completed. The sensing module 4 collects multiple sets of effective steady-state operating current data from the servo motor in drive module 3 under conditions where the product is fully qualified and the extrusion process is stable. The arithmetic mean of the filtered effective data is used as the core target current baseline value. Then, considering the material's thermal sensitivity and the allowable fluctuation range of product quality, an allowable deviation range of 5%-10% is determined above and below the baseline value. The complete target current threshold range is stored in the parameter storage unit of the control module 9. The overload protection threshold is based on the hardware safety of the equipment. First, the rated continuous working current and peak stall current marked on the nameplate of the servo motor of the drive module 3 are extracted as the hardware safety benchmark that cannot be broken. Then, two levels of protection thresholds are set. The first level of overload warning threshold is set at 110%-120% of the rated current of the motor, which is used to trigger speed reduction and audible and visual alarms to remind people to check for abnormalities. The second level of emergency stop protection threshold is set at no more than 150% of the rated current of the motor and no more than 80% of the peak stall current, which is used to trigger emergency stop when extreme abnormalities such as screw jamming and material seizing occur. At the same time, the overload duration judgment condition is added to avoid false triggering caused by instantaneous current fluctuations during production. Both types of thresholds are pre-stored in the control module 9 and are used for closed-loop speed adjustment and equipment safety protection in the subsequent extrusion process, respectively.

[0029] After the formal start of production, the process enters step S2. The control module 9 sends a start-up command to the drive module 3. The servo driver of the drive module 3 drives the servo motor to run at the pre-calibrated initial speed. The output rotational power drives the drive screw 302 to rotate smoothly via the drive rod 301. The screw nut moving seat 5 converts the rotational motion of the drive screw 302 into a linear feed action. During the process, the guide rod 6 provides stable guidance and constraint for the feed action of the screw nut moving seat 5 to avoid swaying or jamming during the feed process. The screw nut moving seat 5 drives the extrusion rod 7 to move linearly, which cooperates with the hollow sleeve 801 fixed on the support frame 2 to complete the continuous and stable extrusion and conveying operation of the molten material in the sleeve. Throughout the entire extrusion process, step S3 is executed synchronously. The Hall current sensor of the sensing module 4 collects the three-phase working current signal of the servo motor in the drive module 3 in real time at a frequency of milliseconds. The collected raw current signal is transmitted to the electrical connection module 10. After the built-in signal filtering unit filters out electromagnetic interference in the production site and signal noise generated by the motor operation, the current signal that truly reflects the motor load status is stably transmitted to the control module 9, providing real-time and accurate working condition feedback data for closed-loop control. Then, the control module 9 synchronously executes step S4. Its built-in control calculation unit compares the received real-time working current effective value with the target current threshold pre-calibrated and stored in step S1 in real time, calculates the current deviation between the real-time current and the target reference value, and clarifies whether the current motor load exceeds, falls below, or is within the normal range required by the process. Finally, the control module 9 executes step S5. Based on the calculated current deviation, it calculates the matching speed adjustment amount through the built-in PID control program, generates the corresponding speed adjustment command, and sends it to the servo driver of the drive module 3 to dynamically correct the output speed of the servo motor. When the real-time operating current exceeds the upper limit of the target threshold, the motor speed is reduced, the extrusion feed speed is slowed down, and the screw load is reduced to bring the current back to the allowable range. When the real-time operating current is lower than the lower limit of the target threshold, the motor speed is increased to accelerate the extrusion feed speed and ensure stable extrusion volume. Through dynamic adjustment, the real-time operating current of the drive module 3 is always kept stable within the pre-calibrated allowable deviation range, thereby offsetting the extrusion instability caused by production variables such as material melt viscosity fluctuations, extrusion load changes, and slight equipment wear. This completes the closed-loop control of the entire extrusion process, ensuring the consistency of extruded product size and quality and the stability of production operations.

[0030] The pre-calibration of step S1 specifically involves: determining the material, product specifications, and process temperature parameters corresponding to the target working condition; collecting multiple sets of steady-state current and actual extrusion volume data of the drive module 3 under standard process conditions; fitting the relationship between current and extrusion volume; and determining the target current threshold, allowable deviation range, and overload protection threshold.

[0031] Furthermore, in the pre-calibration implementation stage before formal mass production, the operator first enters the core basic parameters corresponding to the target working condition into the interactive interface of the control module 9, including the grade, melt index, and filling ratio of the extruded material, the product specifications and tolerance requirements, as well as the standard process temperature and target rated extrusion range of each section of the barrel feeding section, plasticizing section, metering section and forming die. Then, the equipment temperature control system is started to complete the warm-up. After the temperature of each measuring point of the barrel and die stabilizes within the set value ±2℃ range and the heat preservation time meets the material melting requirements, the extrusion system is in a thermal balance state that is completely consistent with formal production, eliminating the interference of temperature fluctuations on material viscosity and screw load. Afterwards, the control module 9 sends 3-5 sets of gradient trial production operation instructions covering the target extrusion volume range to the drive module 3. Each set of instructions lasts for 5-10 minutes. After the extrusion process enters a stable state, data acquisition begins. During the process, the sensing module 4 collects the working current signal of the servo motor in the drive module 3 in real time at a fixed sampling frequency. After the original signal is filtered by the signal filtering unit of the electrical connection module 10 to remove electromagnetic interference and noise, it is converted into stable current effective value data, which is uploaded and stored to the control module 9 in real time. The operator records the actual extrusion volume, product size accuracy, and appearance molding quality data under each set of steady-state working conditions, and selects the effective working condition data that fully meets the quality requirements and has no abnormal fluctuations in the extrusion process. The control module 9 performs fitting calculations on multiple sets of effective steady-state current data and corresponding actual extrusion volume data to establish a model of the correspondence between servo motor operating current, extrusion volume, and screw load. Using the arithmetic average of the steady-state current corresponding to the target rated extrusion volume as the core, the target current threshold is determined. Then, combined with the thermal sensitivity of the material and the allowable fluctuation range of product quality, the allowable deviation range of closed-loop control is defined by fluctuating 5%-8% above and below the target current threshold. At the same time, combined with the rated continuous operating current and peak stall current hardware safety parameters marked on the servo motor nameplate of the drive module 3, the overload warning threshold and emergency shutdown protection threshold are determined in stages. The overload duration judgment condition is added to avoid false triggering caused by instantaneous current fluctuations. Finally, all calibrated parameters are solidified and stored in the parameter storage unit of the control module 9, providing a benchmark for closed-loop control and safety protection in subsequent formal production.

[0032] The speed adjustment in step S5 is as follows: when the real-time operating current is greater than the upper limit of the target current threshold, the control module 9 reduces the output speed of the servo motor; when the real-time operating current is less than the lower limit of the target current threshold, the control module 9 increases the output speed of the servo motor.

[0033] Furthermore, in the real-time execution stage of the closed-loop control of the extrusion operation, the sensing module 4 continuously collects the real-time operating current signal of the servo motor of the drive module 3. After the electrical connection module 10 completes the filtering and noise reduction process, it is transmitted to the control module 9 in real time. The control and calculation unit of the control module 9 continuously compares the received real-time operating current with the upper and lower limits of the pre-calibrated and stored target current threshold in real time. When the real-time operating current is detected to be greater than the upper limit of the target current threshold, it indicates that the current output torque of the servo motor is too high and the screw extrusion load exceeds the stable range set by the process. This is mostly caused by fluctuations in operating conditions such as increased melt viscosity of the material and increased local resistance of the extrusion channel. At this time, the PID control program built into the control module 9 calculates the matching speed reduction range based on the real-time current deviation and generates a corresponding speed reduction control command. This command is sent to the servo driver of the drive module 3 through the electrical connection module 10. The servo driver then adjusts the frequency conversion output parameters to reduce the output speed of the servo motor. This, in turn, slows down the feed speed of the extrusion rod 7 through the transmission mechanism, reduces the extrusion load of the screw, and gradually reduces the operating current of the servo motor to the pre-calibrated allowable deviation range. This avoids problems such as material overheating due to excessive load, product size deviation, or even mechanism jamming. When the control module 9 detects that the real-time operating current is less than the lower limit of the target current threshold, it indicates that the current output torque of the servo motor is too low and the screw extrusion load is insufficient. This is mostly caused by factors such as the decrease in the melt viscosity of the material and fluctuations in the front-end feed rate. At this time, the control module 9 calculates the matching speed increase range through the PID control program, generates a speed-up control command, and sends it to the drive module 3 through the electrical connection module 10. The servo driver drives the servo motor to increase the output speed, accelerates the feed speed of the extrusion rod 7, increases the screw extrusion load, and makes the operating current of the servo motor rise back to the allowable deviation range, ensuring the stability of the extrusion volume and the product molding quality. Through the above bidirectional dynamic adjustment, the influence of the working condition fluctuations is offset throughout the process, and continuous closed-loop stable control of the extrusion process is achieved.

[0034] It also includes safety protection steps: when the control module 9 detects that the real-time operating current exceeds the overload protection threshold, it generates a speed reduction, alarm or shutdown command and sends it to the drive module 3 for execution.

[0035] Furthermore, during the entire extrusion process, the sensing module 4 continuously collects the real-time operating current signal of the servo motor in the drive module 3 at a fixed high frequency. The collected raw current data is filtered, noise-reduced, RMS-converted, and anti-interference processed by the electrical connection module 10, and then transmitted synchronously to the control module 9 without delay. While performing closed-loop speed regulation, the control module 9 simultaneously compares and verifies the received real-time operating current with the overload protection threshold stored in the pre-calibration stage. Once the real-time operating current exceeds the overload protection threshold, the equipment is immediately determined to be in an abnormal overload condition. Such abnormalities are usually caused by foreign objects entering the screw, molten material agglomerating and seizing, transmission mechanism jamming, or a sudden increase in load caused by a sudden increase in material viscosity. Subsequently, the control module 9 will generate corresponding protection commands based on the magnitude and duration of the current over-limit. If it is a minor over-limit and short-term recoverable overload, it will generate speed reduction and audible and visual alarm commands, which will be sent to the drive module 3 through the electrical connection module 10. The servo driver will then perform a speed reduction action to reduce the motor output load and trigger an alarm to prompt the operator to check for process and equipment abnormalities. In the event of an extreme abnormal operating condition such as severe overload or sudden increase in load, an emergency stop command is generated directly and quickly sent to drive module 3. The servo driver immediately cuts off the power output of the servo motor, terminates all operating actions of the equipment, and avoids the servo motor from burning out due to long-term overload and the transmission screw and extrusion mechanism from being deformed and damaged due to strong load, thus ensuring the operational safety of the equipment body and the production site in all aspects.

[0036] It also includes a linkage control step: the control module 9 sends adjustment commands to the matching feeding mechanism and traction mechanism in sync with the current change of the drive module 3 to achieve coordinated adjustment of parameters across the entire line.

[0037] Furthermore, in the entire process of continuous operation of the extrusion production line, the sensing module 4 continuously collects the real-time working current signal of the servo motor of the drive module 3 at high frequency. After the electrical connection module 10 completes signal filtering, anti-interference processing and stable transmission, it is synchronously transmitted to the control module 9. While performing closed-loop speed regulation of the machine, the control module 9 simultaneously analyzes the current change trend, duration, and deviation amplitude of the drive module 3, filters out instantaneous current fluctuation interference during production, and identifies systemic operating condition deviations caused by fluctuations in material melting characteristics, feed rate deviations, and changes in melt pressure. When a continuous deviation of the current from the target range is detected, the control module 9 generates a coordinated adjustment command adapted to the current extrusion state based on the pre-calibrated current-operating condition matching relationship, and sends it to the feeding mechanism and traction mechanism of the extrusion production line through the built-in communication unit. For example, when the current is continuously higher than the upper limit of the target range, while adjusting the speed of the drive module 3, a command to appropriately reduce the feeding rate is issued to the feeding mechanism to reduce the feed load of the screw from the source. At the same time, a matching traction speed adjustment command is issued to the traction mechanism to ensure the consistency between the extrusion volume and the traction speed, and to avoid the product size from exceeding the tolerance. When the current remains below the lower limit of the target range, a command to increase the feeding rate is simultaneously sent to the feeding mechanism to ensure the stability of the material filling degree and extrusion load in the screw. The operating parameters of the traction mechanism are adjusted simultaneously to achieve coordinated adjustment of parameters across the core processes of feeding, extrusion, and traction. This avoids process parameter imbalances and product quality fluctuations caused by single mechanism adjustments, ensuring the continuous and stable operation of the entire extrusion production line and the consistency of product molding quality.

[0038] It also includes a data recording step: the control module 9 records the current, speed, and process parameter data of the entire extrusion process.

[0039] Furthermore, throughout the entire extrusion process, from startup and steady-state production to shutdown and completion, the sensing module 4 continuously collects the real-time operating current data of the servo motor in the drive module 3 at a preset fixed sampling frequency. After signal filtering and format conversion by the electrical connection module 10, the data is stably and synchronously uploaded to the control module 9. The servo driver of drive module 3 synchronously feeds back the real-time output speed, command execution status and other operating data of the servo motor to control module 9 in real time through electrical connection module 10; At the same time, the control module 9 synchronously collects the core process parameters such as the target current threshold, allowable deviation range, and overload protection threshold pre-calibrated for this operation, as well as process data such as speed adjustment commands and abnormal working condition judgment records generated during the closed-loop regulation process; The control module 9 uses a built-in parameter storage unit to continuously record and store the above-mentioned current, speed and process parameters in all dimensions with timestamps, forming a complete and traceable production operation data archive. This can provide historical data reference for subsequent process optimization and parameter reproduction of products of the same specifications, and can also provide complete original data support for cause tracing and problem investigation when product quality deviations or equipment failures occur.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An extrusion screw current monitoring closed loop control device comprising a base mounting frame (1) and a carrier frame (2), characterized in that, The base mounting bracket (1) is provided with a screw current monitoring module. The screw current monitoring module includes a drive module (3), a drive rod (301), a drive screw (302), and a sensing module (4). The drive module (3) includes a servo motor inside. The output end of the servo motor is fixedly connected to the drive rod (301). The end of the drive rod (301) away from the servo motor is fixedly connected to the drive screw (302). The sensing module (4) is located on the outside of the drive screw (302). A guide rod (6) is fixedly connected between the base mounting bracket (1) and the support frame (2). A movable extrusion assembly is provided between the drive screw (302) and the guide rod (6). The movable extrusion assembly includes a hollow sleeve (801) fixedly connected to the support frame (2) and a nut moving seat (5) threadedly connected to the drive screw (302). An extrusion rod (7) is fixedly connected to the nut moving seat (5). The size of the extrusion rod (7) is adapted to the size of the hollow sleeve (801). An adjustment module (9) is installed on the outside of the drive module (3), and an electrical connection module (10) is installed on the outside of the base mounting bracket (1).

2. The extrusion screw current monitoring closed loop control device of claim 1, wherein, The drive module (3) also includes a servo driver that is matched with the servo motor, and the sensing module (4) is a Hall current sensor; The Hall current sensor is installed on the power supply circuit between the output side of the servo driver and the servo motor, and is used to collect the operating current signal of the servo motor.

3. The extrusion screw current monitoring closed loop control device of claim 1, wherein, The outer side of the nut moving seat (5) is symmetrically fixedly connected to a guide slide (501), the guide slide (501) and the guide rod (6) are slidably connected, the upper part of the bearing frame (2) is fixedly connected to an annular bracket (8), and the inner side of the annular bracket (8) and the hollow sleeve (801) are fixedly connected.

4. The extrusion screw current monitoring closed-loop control device according to claim 1, characterized in that, The upper part of the base mounting bracket (1) is fixedly connected to the electrical connection module (10). The electrical connection module (10) includes a terminal block, a signal filtering unit, a power supply interface and a communication interface, which are used to realize signal transmission, electrical isolation and power supply distribution between the sensing module (4), the control module (9) and the drive module (3). The control module (9) includes a controller body, a parameter storage unit, a control calculation unit and a communication unit. The control calculation unit has a built-in PID control program and an overload protection program, which are used to perform speed regulation and abnormal protection actions. The parameter storage unit is used to store pre-calibrated process parameters.

5. A closed-loop control method for extrusion screw current monitoring, characterized in that, The extrusion screw current monitoring closed-loop control device applied to any one of claims 1-4 includes the following steps: S1. Pre-calibrate to determine the target current threshold, allowable deviation range and overload protection threshold of the drive module corresponding to the target extrusion process (3) ; S2. Start the drive module (3), drive the drive screw (302) to rotate through the drive rod (301), drive the nut moving seat (5) and the extrusion rod (7) to move along the guide rod (6), and cooperate with the hollow sleeve (801) to perform the extrusion operation; S3. The working current signal of the drive module (3) is collected in real time through the sensing module (4) and transmitted to the control module (9) through the electrical connection module (10). S4. The control module (9) compares the real-time operating current with the preset target current threshold and calculates the current deviation. S5. The control module (9) adjusts the output speed of the drive module (3) according to the current deviation, so that the working current is stable within the allowable deviation range and the closed-loop control is completed.

6. The extrusion screw current monitoring closed loop control method of claim 5, wherein, The pre-calibration of step S1 is as follows: determine the material, product specifications, and process temperature parameters corresponding to the target working condition, collect the steady-state current and actual extrusion volume data of the drive module (3) under the standard process conditions, fit the relationship between current and extrusion volume, and determine the target current threshold, allowable deviation range and overload protection threshold.

7. The extrusion screw current monitoring closed loop control method of claim 5, wherein, The speed adjustment in step S5 is as follows: when the real-time operating current is greater than the upper limit of the target current threshold, the control module (9) reduces the output speed of the servo motor; when the real-time operating current is less than the lower limit of the target current threshold, the control module (9) increases the output speed of the servo motor.

8. The extrusion screw current monitoring closed loop control method of claim 5, wherein, It also includes safety protection steps: when the control module (9) detects that the real-time operating current exceeds the overload protection threshold, it generates a speed reduction, alarm or shutdown command and sends it to the drive module (3) for execution.

9. The extrusion screw current monitoring closed loop control method of claim 5, wherein, It also includes a linkage control step: the control module (9) sends adjustment instructions to the matching feeding mechanism and traction mechanism in sync with the current change of the drive module (3) to achieve coordinated adjustment of parameters across the entire line.

10. The extrusion screw current monitoring closed loop control method of claim 5, wherein, It also includes data recording steps: the control module (9) records the current, speed and process parameter data of the extrusion process throughout the entire process.

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