Method for controlling slurry height in continuous production process

Abstract

The present disclosure proposes a method of controlling the height of a slurry in a continuous production process for wet forming of the slurry. The method comprises the following steps: obtaining production process information, wherein the production process information comprises: a) the position of a starting section of slurry in the production process; and b) judging whether the field equipment is abnormally operated or not, and adjusting a control output signal applied to the field equipment based on the production process information.According to the method, the control output signal is correspondingly changed according to the complex working condition in the continuous production process of the gypsum board, and the slurry height is dynamically adjusted by adjusting a control strategy.

Description

Technical Field

[0001] This disclosure relates to the field of process control technology, specifically to a method for controlling slurry height in a continuous production process, a continuous production process control system, a computer-readable storage medium, and a computer program product. Background Technology

[0002] In continuous production processes such as paper-faced gypsum board manufacturing, where wet molding with slurry is the core technology, the slurry accumulation height at the extruder is a critical process parameter determining the final board quality. If the slurry height is too low, defects such as insufficient material and incomplete edge sealing can occur, affecting the structural integrity of the board. Conversely, if the height is too high, slurry leakage can occur, leading to material waste, damage to the board's appearance, and exceeding the standard thickness range, thus reducing the uniformity of the finished product's strength. Therefore, maintaining a stable slurry height at the extruder within the preset target range is crucial for ensuring continuous production line operation and high product yield.

[0003] Currently, the industry commonly uses PID (Proportional-Integral-Derivative) control algorithms to construct closed-loop control systems. This involves coordinated control of multiple field devices on the production line to ensure that the slurry height at the extruder remains within a preset target range. However, existing control methods based on a single PID control strategy have significant drawbacks in practical applications and are difficult to adapt to the complex working conditions of continuous gypsum board production.

[0004] First, a single PID control strategy is difficult to adapt to the differentiated needs of multiple operating conditions, easily leading to inefficient or erroneous control. The continuous production process of gypsum board is not always in a stable operating state; various non-stationary operating conditions frequently occur during production. When these non-stationary conditions occur, fixed-parameter PID control cannot adapt to the changes in system characteristics in a timely manner. This ultimately results in inefficient control and may even cause quality problems such as excessive board thickness and surface defects.

[0005] Secondly, a single PID control strategy is inefficient and time-consuming during the production start-up phase. The transition from start-up to stable operation of the production line exhibits significant system initialization characteristics. During this phase, the extruder and its conveying equipment are under low load, and the slurry needs to be rapidly filled to the preset height from nothing. PID control parameters applicable only to stable conditions may result in a slow slurry height increase, requiring repeated adjustments to stabilize the system. This significantly prolongs the start-up time, increases the output of defective sheets during the start-up phase, and reduces overall production efficiency.

[0006] In summary, existing PID-based slurry height control technology for gypsum board production has significant room for improvement in terms of adaptability to operating conditions and control effectiveness during startup, making it difficult to meet the stringent requirements of modern continuous production for efficient and precise control. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this disclosure proposes a method for controlling slurry height during continuous production. This method adjusts the control output signal according to the complex working conditions during the continuous production of gypsum board, and dynamically regulates the slurry height by adjusting the control strategy.

[0008] A first aspect of this disclosure provides a method for controlling slurry height during a continuous production process for wet molding of slurry, comprising: obtaining production process information including: a) the location of the initial segment of the slurry during the production process; and b) whether the field equipment is operating abnormally; and adjusting control output signals applied to the field equipment based on the production process information.

[0009] During the transition from start-up to stable operation of the production line, the control method proposed in this disclosure formulates differentiated control strategies based on the location of the initial slurry section (e.g., whether it has passed through the extrusion device, whether it has passed through the cutting device, etc.). Under complex operating conditions (e.g., when a certain field equipment is in an abnormal operating state), the control method will also adjust the control strategy accordingly to avoid chain reactions such as response lag, control deviation, or even regulation failure in the closed-loop control system.

[0010] In one embodiment, the method further includes: receiving process input signals from the field equipment during the production process, and obtaining production process information based on the process input signals.

[0011] In one embodiment, the field device includes an extrusion device, and the step of obtaining the production process information includes: determining, based on the location of the starting section, that the starting section has not yet passed through the extrusion device; the step of adjusting the control output signal includes: adjusting the current control strategy of the production process to an open-loop control strategy, and generating the control output signal based on the open-loop control strategy.

[0012] In one embodiment, the step of obtaining the production process information further includes: determining, based on the location of the starting section, that the starting section has passed through the extrusion device; the step of adjusting the control output signal further includes: adjusting the current control strategy of the production process to a closed-loop control strategy, and generating the control output signal based on the closed-loop control strategy.

[0013] In one embodiment, the field device includes an extrusion device, and the step of obtaining the production process information includes: knowing that the extrusion device is operating abnormally; the step of adjusting the control output signal includes: adjusting the current control strategy of the production process to an open-loop control strategy, and generating the control output signal based on the open-loop control strategy.

[0014] In one embodiment, the step of obtaining the production process information further includes: knowing that the time for the extrusion device to resume normal operation exceeds a first time threshold; the step of adjusting the control output signal further includes: adjusting the current control strategy of the production process to a closed-loop control strategy, and generating the control output signal based on the closed-loop control strategy.

[0015] In one embodiment, the field equipment further includes a conveying device and a foaming medium injection device, and the closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

[0016] In one embodiment, the closed-loop control strategy further includes a second closed-loop control strategy, which adjusts the foaming parameters so that the real-time height of the slurry at the extrusion device approaches the target height; wherein the step of adjusting the control output signal further includes: executing the first closed-loop control strategy in a first time period and executing the second closed-loop control strategy in a subsequent second time period.

[0017] In one embodiment, the switching between the first time period and the second time period is based on at least one of the following conditions: the fluctuation value of the real-time height of the slurry within a preset time window is less than a first fluctuation threshold; the fluctuation value of the operating parameters within a preset time window is less than a second fluctuation threshold; and the fluctuation value of the foaming parameters within a preset time window is less than a third fluctuation threshold.

[0018] In one embodiment, the field device further includes a cutting device, and the step of obtaining the production process information further includes: determining whether the starting section has passed the cutting device based on the location of the starting section; the step of adjusting the control output signal further includes: when the starting section has not yet passed the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting section has passed the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, the second fine-tuning range being smaller than the first fine-tuning range.

[0019] A second aspect of this disclosure provides a continuous production process control system for wet molding of slurry, the system including field devices and a process control unit. The field devices are configured to send process input signals. The process control unit communicates with the field devices and is configured to perform the following operations: based on the process input signals from the field devices during the production process, obtain production process information, including: a) the location of the initial segment of the slurry during the production process; and b) whether the field devices are operating abnormally; and based on the production process information, adjust the control output signals applied to the field devices.

[0020] In one embodiment, the process control unit is further configured to receive process control signals from the field equipment during the production process.

[0021] In one embodiment, the field device includes an extrusion device, and the process control unit is further configured to: determine, based on the location of the starting section, that the starting section has not yet passed through the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate the control output signal based on the open-loop control strategy.

[0022] In one embodiment, the process control unit is further configured to: determine, based on the location of the starting section, that the starting section has passed through the extrusion device; adjust the current control strategy of the production process to a closed-loop control strategy; and generate the control output signal based on the closed-loop control strategy.

[0023] In one embodiment, the field device includes an extrusion device, and the process control unit is further configured to: detect abnormal operation of the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate the control output signal based on the open-loop control strategy.

[0024] In one embodiment, the process control unit is further configured to: detect that the time for the extrusion device to resume normal operation exceeds a first time threshold; adjust the current control strategy of the production process to a closed-loop control strategy; and generate the control output signal based on the closed-loop control strategy.

[0025] In one embodiment, the field equipment further includes a conveying device and a foaming medium injection device, and the closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

[0026] In one embodiment, the closed-loop control strategy further includes a second closed-loop control strategy, which adjusts the foaming parameters so that the real-time height of the slurry at the extrusion device approaches the target height; the process control unit is further configured to execute the first closed-loop control strategy in a first time period and execute the second closed-loop control strategy in a subsequent second time period.

[0027] In one embodiment, the switching between the first time period and the second time period is based on at least one of the following conditions: the fluctuation value of the real-time height of the slurry within a preset time window is less than a first fluctuation threshold; the fluctuation value of the operating parameters within a preset time window is less than a second fluctuation threshold; and the fluctuation value of the foaming parameters within a preset time window is less than a third fluctuation threshold.

[0028] In one embodiment, the field device further includes a cutting device, and the process control unit is further configured to: determine whether the starting segment has passed the cutting device based on the location of the starting segment; when the starting segment has not yet passed the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting segment has passed the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, the second fine-tuning range being smaller than the first fine-tuning range.

[0029] A third aspect of this disclosure provides a computer-readable storage medium having computer-executable instructions stored thereon for performing the above-described method for controlling slurry height during continuous production.

[0030] A fourth aspect of this disclosure provides a computer program product tangibly stored on a computer-readable storage medium and comprising computer-executable instructions that, when executed, cause at least one processor to perform the above-described method for controlling slurry height during continuous production. Attached Figure Description

[0031] The features, advantages, and other aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description, in which several embodiments of the invention are illustrated by way of example and not limitation, in the drawings:

[0032] Figure 1 A system schematic diagram of a continuous production process according to an embodiment of the present disclosure is shown.

[0033] Figure 2 A schematic diagram of a process control system according to an embodiment of the present disclosure is shown.

[0034] Figure 3 A flowchart illustrating a method for controlling slurry height during continuous production according to an embodiment of the present disclosure is shown.

[0035] Figure 4 A schematic diagram of the extrusion device during normal operation is shown.

[0036] Figure 5 A schematic diagram is shown when the compression device is lifted.

[0037] Figure 6 A schematic diagram of a first closed-loop control strategy according to a first embodiment of the present disclosure is shown.

[0038] Figure 7 A schematic diagram of a second closed-loop control strategy according to a first embodiment of the present disclosure is shown.

[0039] List of reference numerals

[0040] 10: Gypsum mortar

[0041] 101: Stirring device

[0042] 102: Extrusion device

[0043] 1021: Forming port of the extrusion device

[0044] 1022: Inlet of the extrusion unit

[0045] 103: Conveying device

[0046] 104: Cutting device

[0047] 105: Material level detection sensor

[0048] 106: Basic raw material injection device

[0049] 107: Foaming medium injection device

[0050] 108: Position Sensor

[0051] 200: Process Control System

[0052] 201: Process Control Unit Detailed Implementation

[0053] Various exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. While the exemplary methods and apparatuses described below include software and / or firmware executed on hardware among other components, it should be noted that these examples are merely illustrative and should not be considered limiting. For example, it is conceivable that any or all hardware, software, and firmware components may be implemented exclusively in hardware, exclusively in software, or in any combination of hardware and software. Therefore, although exemplary methods and apparatuses have been described below, those skilled in the art will readily understand that the examples provided are not intended to limit the ways in which these methods and apparatuses may be implemented.

[0054] Furthermore, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of methods and systems according to various embodiments of the present invention. It should be noted that the functions indicated in the blocks may occur in a different order than that shown in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0055] The terms "comprising," "including," and similar terms used in this invention are open-ended, meaning "including / including but not limited to," indicating that other content may also be included. The term "based on" means "at least partially based on." The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment," and so on.

[0056] To address the shortcomings of existing technologies, this disclosure proposes a method for controlling slurry height during a continuous production process for wet molding of slurry, comprising: obtaining production process information, including: a) the location of the initial section of the slurry during the production process; and b) whether there is any abnormal operation of the field equipment; and adjusting the control output signal applied to the field equipment based on the production process information.

[0057] The process control disclosed herein pertains to a continuous production process of wet molding of slurry. This process is an industrial technology that directly molds and prepares boards from liquid slurry, and it is widely used in the manufacture of building materials such as gypsum board and fiber cement board. Taking gypsum board production as an example, its core processes include slurry preparation, continuous wet molding, cooling and shaping, and post-processing (such as cutting operations). The system, from right to left, includes a mixing device 101, an extrusion device 102, a conveying device 103, and a cutting device 104. The gypsum slurry 10, shown as a gray strip in the figure, is processed on this production line.

[0058] The mixing device 101 is used in the slurry preparation process on the gypsum board production line. It is connected to both the base raw material injection device (not shown) and the foaming medium injection device (not shown), receiving the base raw materials and foaming medium injected by these devices according to the gypsum board formula ratio. The base raw materials typically include STUCCO (calcium sulfate dihydrate), starch, dispersant, and water; this mixture can be considered as "dense gypsum slurry" before foam is added. The foaming medium typically includes foaming water, AOS (alkenyl sulfonate), foam stabilizer, and air; these are the "pre-made foam" that will be injected into the base raw materials. The mixer adjusts the mixing parameters to uniformly mix the base raw materials and foaming medium, thereby obtaining the prepared gypsum slurry.

[0059] The extrusion device 102 is used in the continuous wet forming process of the gypsum board production line. Gypsum slurry from the mixing device 101 enters the feed hopper at the front end of the extrusion device 102. After being extruded through the forming port 1021 of the extrusion device, the slurry is discharged from the rear end of the extrusion device 102. During this process, the extrusion device 102 simultaneously introduces upper and lower facing papers. As the rollers of the extrusion device continue to run, the upper and lower facing papers clamp and wrap the extruded slurry layer, ultimately forming a continuous wet board blank with a predetermined thickness and completely covered by the upper and lower papers. Among these processes, the control of the slurry height at the extrusion device inlet 1022 (hereinafter referred to as "slurry height at the extrusion device") is a core aspect. (Reference) Figure 1 A material level sensor 105 is located near the extrusion device 102 to monitor the slurry height at the inlet 1022 in real time and feeds the real-time height data back to the process control unit of the process control system. The process control unit adjusts the process control system to stabilize the slurry height within a set process range. The control method and control system proposed in this disclosure aim to effectively control the slurry height at the inlet 1022 of the extrusion device.

[0060] The conveying device 103 is used in the cooling and forming process of the gypsum board production line. The conveying device 103 includes a belt conveyor and an open roller conveyor. The front end of the belt conveyor is synchronously connected to the outlet of the extrusion unit 102, smoothly receiving the wet gypsum board blanks from the extrusion unit 102. The belt conveyor provides stable and continuous transport and support for the wet gypsum board blanks within the tunnel. After the gypsum board has basically solidified on the belt conveyor, the blank is transferred to the open roller conveyor, where, through continuous ventilation and heat dissipation, it finally forms a solid gypsum board.

[0061] The cutting device 104 is used in the post-processing of the gypsum board production line. After the gypsum board comes out of the conveyor 103, it enters the cutting device 104. According to the production order requirements, the cutting device 104 cuts the continuously running strip of boards to a fixed length, thereby obtaining finished gypsum boards with the same specifications.

[0062] Figure 2 A process control system 200 according to an embodiment of the present disclosure is shown, comprising a process control unit 201 and one or more field devices communicating with the process control unit 201. The field devices may be a mixing device 101, an extrusion device 102, a conveying device 103, or a cutting device 104; they may also be a base material injection device 106 or a foaming medium injection device 107 communicating with the mixing device 101; or a material level detection sensor 105 disposed near the extrusion device 102. In this embodiment, the field device may also be a position sensor 108 disposed on the production line, capable of indicating the location of the initial section of the slurry. The process control unit 201 receives signals from the field devices and sends signals to the field devices to control the process control system 200. Specifically, the process control unit 201 sends control routines to the field devices to control the operation of the field devices.

[0063] This method 300 can be applied to Figure 2 The process control system 200 shown includes steps S301 to S303.

[0064] Step S301: Receive process input signals from field equipment during the production process.

[0065] For example, the process control unit can receive material filling time records from the mixing unit and speed records from each conveyor belt on a continuous production line. The process control unit can also receive input signals from position sensors. Furthermore, the process control unit can receive operating status data from various field devices, indicating whether the field devices are in a normal or abnormal operating state. For example, for an extrusion unit, its operating status data can further provide information about abnormal operation, such as abnormal operation caused by mechanical equipment failure.

[0066] Step S302: Based on the process input signals, obtain production process information, including: a) the location of the initial slurry section during the production process; and b) whether there is any abnormal operation of the field equipment. In one example, based on the material filling time of the mixing device and the speed records of each conveyor belt in the continuous production line, the process control unit can roughly estimate the location of the initial slurry section. In another example, based on the input signals provided by the position sensor, the process control unit can directly determine the location of the initial slurry section.

[0067] Step S303: Based on the production process information, adjust the control output signals applied to the field equipment.

[0068] As described in the background section, existing gypsum board production processes typically employ a single PID control strategy, which is ill-suited to the complex operating conditions of continuous gypsum board production. During the transition from start-up to stable operation, differentiated control strategies are needed based on the initial location of the slurry (e.g., whether it has passed through the extrusion device, cutting device, etc.). Compared to the standardized control scheme in the stable operation phase, the control logic in the transition phase should be dynamically adjusted based on the characteristics of the process stage. Furthermore, under complex operating conditions (e.g., when a piece of equipment is in an abnormal operating state), the control system must possess strategy self-adaptation capabilities. If a single PID control scheme is used, abnormal equipment operation will lead to a chain reaction of response lag, control deviation, or even regulation failure in the closed-loop control system. The technical solution proposed in this disclosure highlights the necessity and superiority of multi-mode control strategies in continuous production processes.

[0069] In step S302, it is further determined that the starting section has not yet passed through the extrusion device based on the location of the slurry starting section; in step S303, the current control strategy of the production process is further adjusted to an open-loop control strategy, and a control output signal is generated based on the open-loop control strategy.

[0070] From the initial filling of the basic raw material injection device and the foaming medium injection device until the mixed slurry reaches the extrusion device, this time can be as long as 90 seconds. The process control unit can store the first set of control parameter tables based on the open-loop control strategy, which sets the injection speed and injection volume of the basic raw material injection device, the foaming parameters of the foaming medium injection device, the stirring operation parameters of the agitator, the extrusion height of the extrusion device, and the conveying speed of the conveyor and the cutting time interval of the cutting device. When the production process starts but the initial section has not passed through the extrusion device, the process control unit directly applies the set control parameter tables to each field device, enabling each field device to start working, and at the same time, the entire production line responds quickly.

[0071] In step S302, it is further determined that the starting section has passed through the extrusion device based on the location of the starting section; in step S303, the current control strategy of the production process is further adjusted to a closed-loop control strategy, and a control output signal is generated based on the closed-loop control strategy.

[0072] When the initial section of the slurry passes through the extrusion device, the slurry height at the extrusion device inlet can be used as the controlled variable in closed-loop control. As a core process parameter, the slurry height at this location directly affects the height and quality characteristics of the formed gypsum board. After the slurry passes through the extrusion device, the transition phase of the production line startup enters a more advanced stage. At this time, the process control unit can implement closed-loop regulation of key actuators in the system (such as foaming medium injection devices and conveying devices) through a PID control algorithm based on the real-time monitored actual slurry height value and the preset target value, thereby achieving dynamic and precise control of the slurry height.

[0073] In step S302, it is further determined that the extrusion device is operating abnormally; in step S303, the current control strategy of the production process is further adjusted to an open-loop control strategy, and a control output signal is generated based on the open-loop control strategy.

[0074] Figure 4 A schematic diagram of the extrusion device 102 during normal operation is shown. Referring to the enlarged view on the left, the forming port 1021 of the extrusion device extrudes the passing gypsum slurry 10. Figure 5 A schematic diagram is shown when the extrusion device 102 is lifted. Referring to the enlarged view on the left, there is a certain gap between the forming port 1021 of the extrusion device and the gypsum slurry 10 below, which prevents it from completing the extrusion operation.

[0075] During production, workers discovered dirt on the extrusion unit and needed to temporarily lift it for cleaning, placing the extrusion unit in an abnormal operating state. If closed-loop control continued, the process control unit would still adjust based on the deviation between the setpoint and actual slurry height. Since the slurry could not be effectively extruded, its height loss exceeded the effective adjustment range of the original closed-loop control. Therefore, the process control unit could store a second set of control parameter tables based on an open-loop control strategy, specifically designed to handle the situation where the extrusion unit is lifted.

[0076] In step S302, it is further determined that the time for the extrusion device to resume normal operation exceeds a first time threshold; in step S303, the current control strategy of the production process is further adjusted to a closed-loop control strategy, and a control output signal is generated based on the closed-loop control strategy.

[0077] Current technology uses a single PID controller for the entire production process. After the worker wipes away the dirt and puts down the extruder, the slurry level may have deviated from the normal range (e.g., too high or too low), requiring the PID controller to re-search for suitable control parameters (such as foaming parameters, conveying speed, etc.). Therefore, the settling time may be longer, potentially leading to overshoot or oscillation. Activating closed-loop control only after the extruder has resumed operation for more than a first time threshold (e.g., 10 seconds) can avoid these issues and reduce waste material caused by prolonged settling time.

[0078] Optionally, in step S302, production process information is obtained based on the process control signal, wherein the production process information may further include c) the real-time height of the slurry at the extrusion device.

[0079] refer to Figure 1 The material level detection sensor 105 near the extrusion unit 102 can send real-time height data of the slurry 10 at the inlet 1022 of the extrusion unit to the process control unit 201. This data can be used to observe whether the current process control system is operating normally. If the slurry height indicates an abnormality in the production process, then, according to step S303, the control output signals applied to the field equipment can be adjusted based on the production process information.

[0080] In step S302, it is further determined that the real-time height of the slurry at the extrusion device exceeds a preset height range; in step S303, the current control strategy of the production process is further adjusted to an open-loop control strategy, and the control output signal is generated based on the open-loop control strategy.

[0081] During gypsum board production, when the system is operating smoothly, the normal height range of the slurry at the extrusion device is typically set to 15 mm to 25 mm. This range can be written into the process control unit as a preset height range. Under specific circumstances, if the slurry height measured by the level sensor is significantly lower than the normal range (e.g., below 5 mm, or even 0 mm), it may indicate one of two situations. The first situation is that the initial section has not yet passed through the extrusion device. At this time, the slurry has not yet entered a stable flow state and needs to wait for the process parameters to adjust naturally. The second situation is that the slurry flow is interrupted, which may be caused by a malfunction in the feeding equipment or an abnormal supply of raw materials. Furthermore, if the slurry height value output by the level sensor shows an abnormally extreme value (e.g., above 30 mm or below 0 mm), it usually indicates that the sensor is malfunctioning (e.g., probe misalignment, signal interference, etc.).

[0082] When the slurry level exceeds its normal adjustment range, or when the control system cannot reliably sense the process status, the feedback-based closed-loop control should be stopped immediately and switched to the preset open-loop control mode. This measure can prevent equipment damage or product quality accidents caused by incorrect adjustments.

[0083] The following will describe the closed-loop control strategy applicable to the production process based on the first embodiment. This closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

[0084] Figure 6 A first closed-loop control strategy according to a first embodiment of the present disclosure is illustrated, wherein the strategy adjusts the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device. The first closed-loop control strategy includes a closed-loop control P1 and a cascaded closed-loop control P2. Closed-loop control P1 serves as the main control loop, and its input is the target height H of the slurry at the extrusion device. target and real-time height H real The output is the fine-tuning value of the operating parameters of the conveying device. This operating parameter can be the belt conveyor speed. Closed-loop control P1 is based on H. target and H real Calculate the height deviation of the slurry And by using, for example, PID control algorithms to calculate It dynamically compensates for slurry height deviations by adjusting the conveying speed of the conveying device.

[0085] In a specific example, the target height H of the slurry at the extrusion device target The slurry height H is set to 20 mm and monitored in real time. real The value is 18 mm, which is lower than the target height. This is calculated based on the PID control algorithm. The value is 0.997. Given that the base speed of the conveyor is 1000 rpm, the closed-loop control P1 fine-tunes the conveyor speed to 997 rpm. (Reference) Figure 1 In this way, as the speed of the left conveying device 103 slows down, more slurry will accumulate at the extrusion device 102, thereby increasing the slurry height.

[0086] The closed-loop control P2 serves as the secondary control loop, and its inputs are the target value N0 and the fine-tuning value of the conveyor's operating parameters. Its output is the foaming parameter M from the foaming medium input device. This foaming parameter can be the foaming factor, which directly determines the number and distribution of bubbles in the core. The larger the foaming factor, the larger the bubbles in the slurry, and the further the volume of the slurry increases. Closed-loop control P2 is based on N0 and The deviation in conveying speed is calculated, and M is determined using, for example, a PID algorithm. The height of the slurry is dynamically changed by adjusting the foaming factor.

[0087] In a specific example, the target value N0 of the conveyor's operating parameters is set to 1, corresponding to a base speed of 1000 rpm; the fine-tuning value of the conveyor's operating parameters... The value is 0.997, corresponding to a conveying speed of 997 rpm. Since the conveying speed is lower than the reference speed, this indicates that the slurry height at the extrusion device is too low. Based on the PID control algorithm, M is calculated to be 1010 L / min, which is greater than the reference foaming factor of 1000 L / min in the formulation. (Reference) Figure 1 In this way, as the foaming medium input device injects more foaming medium into the mixing device 101, the volume of the slurry is further increased, thereby increasing the height of the slurry at the extrusion device 102.

[0088] In the above embodiments, the first closed-loop control strategy uses a cascaded system to coordinate the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, thereby achieving rapid adjustment of the slurry height at the extrusion device. The significant advantage of this strategy is its fast response speed, which effectively reduces downstream waste generation and allows the slurry height to quickly reach the target range.

[0089] Compared to adjusting the slurry height using foaming agents, adjusting the height using conveying speed is more efficient and has a faster response. In other embodiments, the first closed-loop control strategy can also adjust the operating parameters of the conveying device to make the real-time height of the slurry at the extrusion device approach the target height. For example, in Figure 6 In this case, the first closed-loop control strategy may only include closed-loop control P1, without the need to introduce closed-loop control P2.

[0090] Optionally, within the framework of using the first closed-loop control strategy, in step S302, based on the location of the starting segment, it is determined whether the starting segment has passed through the cutting device; in step S303, when the starting segment has not yet passed through the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting segment has passed through the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, wherein the second fine-tuning range is smaller than the first fine-tuning range.

[0091] For example, in the above embodiment, when the initial section has not yet passed the cutting device, the first fine-tuning range of the operating parameters (such as the conveying speed) is 0.99 to 1.01 times the reference value. Taking a reference speed of 1000 rpm as an example, the closed-loop control P1 can adjust the conveying speed between 990 rpm and 1010 rpm to quickly respond to deviations in slurry height and approach the target value. When the initial section has passed the cutting device, the second fine-tuning range of the operating parameters is reduced to 0.994 to 1.006 times the reference value, corresponding to a conveying speed adjustment range of 994 rpm to 1006 rpm. At this time, the adjustment range of the closed-loop control P1 is limited to avoid dimensional deviations or edge defects in the gypsum board to be cut due to parameter fluctuations.

[0092] Optionally, in step S303, when the starting section has not yet passed the cutting device, the foaming parameter in the first closed-loop control strategy has a third fine-tuning range; when the starting section has passed the cutting device, the foaming parameter in the first closed-loop control strategy has a fourth fine-tuning range, wherein the fourth fine-tuning range is smaller than the third fine-tuning range.

[0093] For example, in the above embodiment, when the initial section has not yet passed through the cutting device, the foaming parameters (such as the foaming factor) can be adjusted between 980 L / min and 1200 L / min. However, when the initial section has passed through the cutting device, the adjustment range of the foaming factor is further narrowed, and it can only be adjusted between 990 L / min and 1100 L / min.

[0094] In general, when the initial section of the slurry is at the front end of the production line, fluctuations in parameters such as conveyor speed and foaming factor have not yet manifested their impact on subsequent processes (such as cutting). This allows for rapid adjustments within a wider fine-tuning range to quickly stabilize process parameters. However, once the gypsum board in the initial section has been cut to standard lengths, excessive adjustments to the conveyor speed or foaming factor may lead to deformation of the cut boards. Therefore, the fine-tuning range needs to be narrowed to avoid affecting the quality of the finished product due to parameter fluctuations.

[0095] Furthermore, the closed-loop control strategy applicable to this production process also includes a second closed-loop control strategy, which adjusts the foaming parameters to make the real-time height of the slurry at the extrusion device approach the target height. The step of adjusting the control output signal further includes: executing the first closed-loop control strategy in a first time period, and executing the second closed-loop control strategy in a subsequent second time period.

[0096] Figure 7 A second closed-loop control strategy according to a first embodiment of the present disclosure is shown, wherein the strategy adjusts the foaming parameters of the foaming medium injection device. The second closed-loop control strategy includes a closed-loop control P3, the input of which is the target height H of the slurry at the extrusion device. target and real-time height Hreal The output is the foaming parameter M of the foaming medium input device. Closed-loop control P3 is based on H. target and H real Calculate the height deviation of the slurry Furthermore, M is calculated using algorithms such as PID control. This dynamically compensates for slurry height deviations by adjusting the foaming parameters of the foaming medium input device.

[0097] In a specific example, the target height H of the slurry at the extrusion device target The slurry height H is set to 20 mm and monitored in real time. real The height is 19.5 mm, which is lower than the target height. Based on the PID control algorithm, M is calculated to be 1005 L / min, which is greater than the baseline foaming factor of 1000 L / min in the formulation. (Reference) Figure 1 In this way, as the foaming medium input device injects more foaming medium into the mixing device 101, the volume of the slurry is further increased, thereby increasing the height of the slurry at the extrusion device 102.

[0098] During the first production phase (which can be understood as the start-up or adjustment stage), the height of the slurry at the extrusion device may deviate significantly due to equipment startup, raw material fluctuations, or process parameter changes. At this time, it is necessary to simultaneously adjust the parameters of the conveying device and the foaming medium injection device to quickly stabilize the slurry height. However, during the second production phase (which can be understood as the stable operation stage), the slurry height is close to the target value. At this point, only fine-tuning the foaming parameters is needed to maintain a stable height, avoiding equipment wear or energy waste caused by frequent adjustments to the conveying speed.

[0099] The switching between the first time period and the second time period is based on at least one of the following conditions: e) the fluctuation value of the real-time height of the slurry within the preset time window is less than the first fluctuation threshold; d) the fluctuation value of the operating parameters within the preset time window is less than the second fluctuation threshold; f) the fluctuation value of the foaming parameters within the preset time window is less than the third fluctuation threshold.

[0100] Regarding condition e), in a specific example, the slurry height fluctuation should be continuously below ±0.5 mm within a preset time window of 30 seconds. Regarding condition d), in a specific example, the conveying speed fluctuation should be continuously below ±2 rpm within a preset time window of 60 seconds. Regarding condition f), in a specific example, the foaming rate fluctuation should be continuously below ±1 L / min within a preset time window of 120 seconds. Once one of the above conditions is met, it indicates that the first closed-loop control has stabilized, and the process control unit can close the first closed-loop control and open the second closed-loop control.

[0101] The following section will elaborate on the closed-loop control strategy applicable to this production process based on the second embodiment.

[0102] The closed-loop control strategy in the second embodiment adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height. The closed-loop control strategy includes a third closed-loop control strategy and a fourth closed-loop control strategy. The response speed of the third closed-loop control strategy is faster than that of the fourth closed-loop control strategy, but the stability margin of the third closed-loop control strategy is lower than that of the fourth closed-loop control strategy. In step S303, the step of adjusting the control output signal further includes: executing the third closed-loop control strategy in a first time period, and executing the fourth closed-loop control strategy in a subsequent second time period.

[0103] For example, the input to both the third and fourth closed-loop control strategies is the target height H of the slurry at the extrusion device. target and real-time height H real The outputs of both strategies are the foaming parameters M of the foaming medium input device. Both the third and fourth closed-loop control strategies are PID control, but with different PID control parameters. In one example, the Kp, Ki, and Kd of the third closed-loop control strategy are 5, 0.1, and 2, respectively; while the Kp, Ki, and Kd of the fourth closed-loop control strategy are 2, 0.5, and 0.5, respectively. In the third closed-loop control strategy, high Kp and high Kd make the system respond quickly to slurry height deviations, while low Ki may cause the slurry height to oscillate around the target value (e.g., fluctuations of ±1~2 mm). Conversely, in the fourth closed-loop control strategy, low Kp and low Kd make the system adjustment smoother but require more time, while high Ki stabilizes the slurry height within the target value range of ±0.5 mm without significant oscillations.

[0104] Based on the different characteristics of the third and fourth closed-loop control strategies, the process control unit can apply the third closed-loop control strategy during the system startup or adjustment phase, and apply the fourth closed-loop control strategy during the system stable operation phase.

[0105] It should be noted that although this article mainly uses PID control as an example to implement closed-loop control, those skilled in the art will understand that in suitable process control systems, closed-loop control may also be achieved through improved PID control, cascade control, feedforward-feedback composite control, or model predictive control, etc.

[0106] Furthermore, this disclosure also proposes a continuous production process control system for the wet molding of slurry, the system comprising: Figure 2The diagram shows one or more field devices (e.g., 101, 102, 103, 104, 105, 106, 107, 108) and a process control unit 201. The field devices are configured to send process input signals. The process control unit communicates with the field devices and is configured to perform the following operations: obtain production process information based on the process input signals from the field devices during production, including: a) the location of the initial section of the slurry during production; and b) whether there is any abnormal operation of the field devices; and adjust the control output signals applied to the field devices based on the production process information.

[0107] In one embodiment, the process control unit is also configured to receive process control signals from field devices during the production process.

[0108] In one embodiment, the field device includes an extrusion device. The process control unit is also configured to: determine, based on the location of the starting section, that the starting section has not yet passed through the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate a control output signal based on the open-loop control strategy.

[0109] In one embodiment, the process control unit is further configured to: determine that the starting section has passed through the extrusion device based on the location of the starting section; adjust the current control strategy of the production process to a closed-loop control strategy; and generate a control output signal based on the closed-loop control strategy.

[0110] In one embodiment, the process control unit is further configured to: detect abnormal operation of the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate a control output signal based on the open-loop control strategy.

[0111] In one embodiment, the process control unit is further configured to: detect that the time for the extrusion device to resume normal operation exceeds a first time threshold; adjust the current control strategy of the production process to a closed-loop control strategy; and generate a control output signal based on the closed-loop control strategy.

[0112] In one embodiment, the field equipment further includes a conveying device and a foaming medium injection device, and the closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

[0113] In one embodiment, the closed-loop control strategy further includes a second closed-loop control strategy, which adjusts the foaming parameters so that the real-time height of the slurry at the extrusion device approaches the target height. The process control unit is also configured to execute the first closed-loop control strategy in a first time period and execute the second closed-loop control strategy in a subsequent second time period.

[0114] In one embodiment, the switching between the first time period and the second time period is based on at least one of the following conditions: the fluctuation value of the real-time height of the slurry within the preset time window is less than the first fluctuation threshold; the fluctuation value of the operating parameters within the preset time window is less than the second fluctuation threshold; and the fluctuation value of the foaming parameters within the preset time window is less than the third fluctuation threshold.

[0115] In one embodiment, the field device further includes a cutting device. The process control unit is also configured to: determine whether the starting section has passed the cutting device based on the location of the starting section; when the starting section has not yet passed the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting section has passed the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, the second fine-tuning range being smaller than the first fine-tuning range.

[0116] Furthermore, the method for controlling slurry height during continuous production as proposed in this disclosure can be implemented using a computer-readable storage medium. The computer-readable storage medium carries computer-readable program instructions for executing the various embodiments of this application. The computer-readable storage medium can be a tangible device capable of holding and storing instructions used by an instruction execution device. The computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (not exhaustive) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combinations thereof. The computer-readable storage medium used herein is not to be interpreted as a transient signal itself, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0117] Therefore, in another embodiment, this application proposes a computer-readable storage medium having computer-executable instructions stored thereon for performing the method of controlling slurry height in a continuous production process proposed in this disclosure.

[0118] This application also proposes a computer program product tangibly stored on a computer-readable storage medium and including computer-executable instructions that, when executed, cause at least one processor to perform the methods of various embodiments of this application.

[0119] Generally, the various example embodiments of this application can be implemented in hardware or dedicated circuitry, software, firmware, logic, or any combination thereof. Some aspects can be implemented in hardware, while others can be implemented in firmware or software that can be executed by a controller, microprocessor, or other computing device. When aspects of the embodiments of this application are illustrated or described as block diagrams, flowcharts, or using some other graphical representation, it will be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented as non-limiting examples in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

Claims

1. A method for controlling slurry height during a continuous production process, said production process being used for wet molding of slurry, comprising: Obtain production process information, including: a) the location of the initial section of the slurry in the production process; and b) whether there is any abnormal operation of the on-site equipment; and Based on the production process information, the control output signals applied to the field equipment are adjusted.

2. The method according to claim 1, further comprising: Receive process input signals from the field equipment during the production process, and obtain the production process information based on the process input signals.

3. The method according to claim 1, wherein, The field equipment includes a pressing device. The steps for obtaining the production process information include: determining, based on the location of the starting section, that the starting section has not yet passed through the extrusion device; The step of adjusting the control output signal includes: adjusting the current control strategy of the production process to an open-loop control strategy, and generating the control output signal based on the open-loop control strategy.

4. The method according to claim 3, wherein, The step of obtaining the production process information further includes: determining, based on the location of the starting section, that the starting section has passed through the extrusion device; The step of adjusting the control output signal further includes: adjusting the current control strategy of the production process to a closed-loop control strategy, and generating the control output signal based on the closed-loop control strategy.

5. The method according to claim 1, wherein, The field equipment includes a pressing device. The steps for obtaining the production process information include: knowing that the extrusion device is not operating normally; The step of adjusting the control output signal includes: adjusting the current control strategy of the production process to an open-loop control strategy, and generating the control output signal based on the open-loop control strategy.

6. The method according to claim 5, wherein, The step of obtaining the production process information further includes: knowing that the time for the extrusion device to resume normal operation exceeds a first time threshold; The step of adjusting the control output signal further includes: adjusting the current control strategy of the production process to a closed-loop control strategy, and generating the control output signal based on the closed-loop control strategy.

7. The method according to claim 4 or 6, wherein, The field equipment also includes a conveying device and a foaming medium injection device. The closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

8. The method according to claim 7, wherein, The closed-loop control strategy also includes a second closed-loop control strategy, which adjusts the foaming parameters so that the real-time height of the slurry at the extrusion device approaches the target height. The step of adjusting the control output signal further includes: executing the first closed-loop control strategy in a first time period and executing the second closed-loop control strategy in a subsequent second time period.

9. The method according to claim 8, wherein, The switching between the first time period and the second time period is based on at least one of the following conditions: The fluctuation value of the real-time height of the slurry within a preset time window is less than a first fluctuation threshold. The fluctuation value of the operating parameter within the preset time window is less than the second fluctuation threshold; The fluctuation value of the foaming parameter within the preset time window is less than the third fluctuation threshold.

10. The method according to claim 7, wherein, The field equipment also includes a cutting device. The step of obtaining the production process information further includes: determining whether the starting section has passed through the cutting device based on the location of the starting section; The step of adjusting the control output signal further includes: when the starting section has not yet passed the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting section has passed the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, the second fine-tuning range being smaller than the first fine-tuning range.

11. A continuous production process control system, the production process being used for wet molding of slurry, the system comprising: Field devices, configured to send process input signals; A process control unit, which communicates with the field devices, is configured to perform the following operations: Based on the process input signals from the field equipment during the production process, production process information is obtained, including: a) the location of the initial section of the slurry during the production process; and b) whether the field equipment is operating abnormally; and Based on the production process information, the control output signals applied to the field equipment are adjusted.

12. The system according to claim 11, wherein, The process control unit is also configured to receive process control signals from the field equipment during the production process.

13. The system according to claim 11, wherein, The field equipment includes the extrusion device. The process control unit is further configured to: determine, based on the location of the starting section, that the starting section has not yet passed through the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate the control output signal based on the open-loop control strategy.

14. The system according to claim 13, wherein, The process control unit is further configured to: determine, based on the location of the starting section, that the starting section has passed the extrusion device; adjust the current control strategy of the production process to a closed-loop control strategy; and generate the control output signal based on the closed-loop control strategy.

15. The system according to claim 11, wherein, The field equipment includes the extrusion device. The process control unit is further configured to: detect abnormal operation of the extrusion device; adjust the current control strategy of the production process to an open-loop control strategy; and generate the control output signal based on the open-loop control strategy.

16. The system according to claim 15, wherein, The process control unit is further configured to: detect that the time for the extrusion device to resume normal operation exceeds a first time threshold; adjust the current control strategy of the production process to a closed-loop control strategy; and generate the control output signal based on the closed-loop control strategy.

17. The system according to claim 14 or 16, wherein, The field equipment also includes a conveying device and a foaming medium injection device. The closed-loop control strategy includes a first closed-loop control strategy, which adjusts at least one parameter among the operating parameters of the conveying device and the foaming parameters of the foaming medium injection device, so that the real-time height of the slurry at the extrusion device approaches the target height.

18. The system according to claim 17, wherein, The closed-loop control strategy also includes a second closed-loop control strategy, which adjusts the foaming parameters so that the real-time height of the slurry at the extrusion device approaches the target height. The process control unit is further configured to execute the first closed-loop control strategy in a first time period and execute the second closed-loop control strategy in a subsequent second time period.

19. The system according to claim 18, wherein, The switching between the first time period and the second time period is based on at least one of the following conditions: The fluctuation value of the real-time height of the slurry within a preset time window is less than a first fluctuation threshold. The fluctuation value of the operating parameter within the preset time window is less than the second fluctuation threshold; The fluctuation value of the foaming parameter within the preset time window is less than the third fluctuation threshold.

20. The system according to claim 17, wherein, The field equipment also includes a cutting device. The process control unit is further configured to: determine whether the starting section has passed through the cutting device based on the location of the starting section; When the starting segment has not yet passed the cutting device, the operating parameters in the first closed-loop control strategy have a first fine-tuning range; when the starting segment has passed the cutting device, the operating parameters in the first closed-loop control strategy have a second fine-tuning range, which is smaller than the first fine-tuning range.

21. A computer-readable storage medium having computer-executable instructions stored thereon for performing a method for controlling slurry height in a continuous production process according to any one of claims 1-10.

22. A computer program product tangibly stored on a computer-readable storage medium and comprising computer-executable instructions that, when executed, cause at least one processor to perform a method for controlling slurry height in a continuous production process according to any one of claims 1-10.

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