A steel coil leveler continuous feeding control system

Abstract

A kind of steel coil flattening machine continuous feeding control system, it is related to metal sheet processing technical field, including decoiling tension control module, feeding speed synchronization module, material state detection module and central control unit;The system passes through first, second tension sensor real-time acquisition decoiling outlet and the tension difference of flattening entrance, by servo drive device dynamic adjustment decoiling speed;Adopt high-resolution encoder ≥10000 pulse / rotation and speed sensor construct PID closed loop, make feeding speed and flattening speed synchronization error ≤±0.5%;Along the feeding channel, at least three groups of laser displacement sensors are arranged, the verticality of strip steel and lateral offset are synchronously monitored, and when the limit is exceeded, the hierarchical intervention strategy is triggered;Central control unit is industrial PLC or embedded industrial computer, supports thickness parameter automatic call, man-machine interaction and MES communication;System realizes active inhibition to accumulation, stretching and offset within 200mm range before strip steel enters flattening roller, so that finished product surface indentation defect rate is stably reduced to below 0.1%.

Description

Technical Field

[0001] This application relates to the field of metal sheet processing technology, specifically to a continuous feeding control system for a steel coil leveling machine. Background Technology

[0002] As is well known, in automated stamping production lines, coil levelers are used to straighten coils, eliminating internal stress and bending in the material. The flatness of the output sheet directly determines the quality of the finished stamped parts. Currently, mainstream coil feeding systems typically consist of an uncoiler, a feeding roller assembly, and a leveler connected in series. After the uncoiler releases the coil, the strip is conveyed via the feeding rollers to the gap between the leveler's rollers for flattening. However, traditional systems generally use open-loop control. The uncoiler feeds at a constant speed based on a preset rotation speed, the feeding rollers are driven by a fixed-frequency asynchronous motor, and the leveler operates independently. There is no real-time speed linkage or feedback mechanism between the three. During equipment start-up, shutdown, acceleration, or speed changes, speed mismatch easily occurs between the feeding end and the leveling end, leading to localized accumulation or overstretching of the strip in the feeding channel. During the unloading process, steel coils are prone to lateral swaying and sag deformation due to their own inertia, changes in coil diameter, and uneven tension distribution. Traditional equipment lacks online monitoring and active correction functions for the strip shape, causing interlayer misalignment or bending of the strip before it enters the leveling rolls, exacerbating stress concentration during the rolling process. In addition, when changing to steel coils of different thicknesses, the gap of the feeding channel, the pressure of the pressing arm, and the position of the guide rollers need to be manually adjusted by the operator's experience. The adjustment cycle is long and the parameter matching degree is low, which often leads to the strip being forcibly squeezed at the entrance of the roll gap, forming periodic indentation defects, which seriously affect the surface quality. Especially in continuous production scenarios with high surface precision requirements, such as automotive panels and home appliance panels, such defects can easily cause the entire batch of materials to be downgraded or scrapped, becoming a core bottleneck restricting production yield and product consistency. Summary of the Invention

[0003] This application provides a continuous feeding control system for a steel coil leveling machine, including: an uncoiling tension control module, a feeding speed synchronization module, a material condition detection module, and a central control unit; the uncoiling tension control module includes a first tension sensor located at the uncoiler outlet, a second tension sensor located at the leveling machine inlet, and a servo drive device for adjusting the uncoiling speed; the feeding speed synchronization module includes a servo motor driving the feeding roller, an encoder connected thereto, and a speed sensor for detecting the linear speed of the leveling machine's working roller; the material condition detection module includes at least three sets of laser displacement sensors arranged along the feeding channel for monitoring the strip sag and lateral offset; the central control unit receives signals from each sensor, calculates the tension difference in real time, and adjusts the uncoiling speed, using a PID algorithm to control the synchronization error between the feeding speed and the leveling speed to ≤±0.5%, and when any laser sensor detects that the sag exceeds the limit, it performs active intervention by deceleration and tension fine-tuning to prevent the strip from being squeezed and piled up before entering the leveling roller.

[0004] Furthermore, the central control unit controls the uncoiler to accelerate or decelerate according to the positive or negative direction of the tension difference ΔF between the first tension sensor and the second tension sensor: when ΔF ≥ 0, the uncoiler accelerates to relieve tension, and when ΔF ≤ 0, the uncoiler decelerates to eliminate accumulation.

[0005] Furthermore, during the start-up, shutdown, or speed change phases of the leveling machine, the central control unit employs an S-curve acceleration / deceleration algorithm to smoothly transition the speed of the feeding rollers, avoiding material impact caused by sudden speed changes.

[0006] Furthermore, the laser displacement sensor has a multi-point lateral scanning structure, which can simultaneously detect the strip sag and lateral offset. When the offset exceeds a preset threshold, an alarm or correction command is triggered.

[0007] Furthermore, the central control unit pre-stores standard parameter sets corresponding to steel coils of different thicknesses, including feeding gap, pressing pressure, tension threshold and sag safety threshold. After the operator inputs the thickness, the system automatically calls up and configures the parameters.

[0008] Furthermore, when the laser sensor detects that the sag exceeds the limit, the central control unit intervenes according to a graded strategy: first, it reduces the feeding speed, then it fine-tunes the unwinding tension; if it does not recover within 2 seconds, it triggers the leveler to reduce its speed.

[0009] Furthermore, the first and second tension sensors are contact tension detection rollers with a sampling frequency of ≥100Hz and use strain gauge sensing elements to ensure stable acquisition of dynamic tension signals.

[0010] Furthermore, the servo motor is an AC servo motor, and the encoder resolution is ≥10000 pulses / revolution, forming a high-precision closed-loop speed control system.

[0011] Furthermore, the central control unit is an industrial PLC or embedded industrial computer, equipped with a human-machine interface, supporting parameter setting, status monitoring, historical data storage, and communication with the MES system.

[0012] Furthermore, the system continuously suppresses accumulation, stretching, and displacement within 200mm before the strip enters the leveling roll, reducing the surface indentation defect rate of the finished product to below 0.1%, making it suitable for continuous production scenarios with high surface quality requirements, such as automotive panels and home appliance panels.

[0013] By applying the technical solution of this application, a first tension sensor and a second tension sensor are respectively installed at the uncoiler exit and the leveler inlet, and their signals are transmitted to the central control unit. The tension difference is calculated in real time, and the uncoiling speed is dynamically adjusted, thereby effectively stabilizing the tension fluctuation of the strip steel throughout the feeding process. Simultaneously, a servo motor drives the feeding roller and couples it with an encoder. In conjunction with a speed sensor that detects the linear speed of the leveler's working roller, the central control unit uses a PID algorithm to precisely control the synchronization of the feeding speed and the leveling speed, ensuring that the error between the two is maintained within ±0.5%, thus completely eliminating the influence of tension fluctuations caused by tension differences. Speed ​​mismatch leads to strip stretching or relaxation. In addition, by arranging at least three sets of laser displacement sensors along the feeding channel, the sag and lateral offset of the strip are monitored in real time. When any sensor detects a risk of sag exceeding the limit, the central control unit immediately triggers an active intervention mechanism of deceleration and tension fine-tuning to prevent the strip from accumulating, wrinkling or being squeezed before entering the leveling roll. This systematically solves the three core problems in the existing technology: asynchronous feeding and leveling speeds, unstable tension and feeding compression and accumulation. It achieves high-precision, high-stability and high-safety coordinated control of the steel coil leveling and feeding process. Attached Figure Description

[0014] Figure 1 This is a system principle block diagram of the present invention; Figure 2 This is a flowchart of the control logic of the central control unit of the present invention. Detailed Implementation

[0015] The present invention will be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0016] Combined with appendix Figures 1-2 According to this embodiment, a continuous feeding control system for a steel coil leveling machine includes: Step 1: The unwinding tension control module includes a first tension sensor located at the exit of the uncoiler, a second tension sensor located at the inlet of the leveler, and a servo drive device for adjusting the unwinding speed. The unwinding tension control module includes: a first tension sensor located at the exit of the uncoiler, a second tension sensor located at the entrance of the leveler, and a servo drive device connected to the power mechanism of the uncoiler.

[0017] The first tension sensor is used to collect the tension signal of the steel coil in real time after it is released from the uncoiler and enters the initial section of the feeding channel; the second tension sensor is used to collect the tension signal of the strip steel at the end of the feeding channel before it enters the working roll group of the leveler.

[0018] The central control unit receives the tension data output by the first tension sensor and the second tension sensor, calculates the tension difference ΔF = F2 - F1 in real time, where F1 is the value detected by the first tension sensor and F2 is the value detected by the second tension sensor, and dynamically adjusts the output speed of the servo drive device according to the sign and amplitude of the difference, thereby realizing closed-loop control of the unwinding speed. When ΔF ≥ 0, it indicates that the tension at the leveler inlet is not less than the tension at the uncoiler outlet. The system determines that there is a stretching trend in the feeding channel or that the tension transmission is sufficient. The system controls the servo drive device to appropriately accelerate the uncoiler feeding to alleviate the risk of excessive stretching of the strip in the channel. When ΔF ≤ 0, it indicates that the inlet tension of the leveler is lower than the outlet tension of the uncoiler. The system determines that there is a lack of tension or a local accumulation trend in the feeding channel. The servo drive device is controlled to appropriately reduce the speed of the uncoiler to eliminate the loosening and accumulation of strip steel in the channel.

[0019] Through the above structure and control strategy, real-time sensing and adaptive balancing of tension state between unwinding and leveling processes are achieved, providing a basic guarantee for subsequent speed synchronization and material morphology stability control.

[0020] Step 2: The feeding speed synchronization module includes a servo motor that drives the feeding roller, an encoder connected to it, and a speed sensor that detects the linear speed of the working roller of the leveling machine. In this embodiment, the feeding speed synchronization module includes: an AC servo motor that drives the feeding roller assembly, a high-resolution encoder coaxially connected to the servo motor, and a speed sensor installed on the end of the working roller shaft of the leveling machine.

[0021] The AC servo motor receives speed commands from the central control unit via a frequency converter driver, precisely controlling the rotational angular displacement and linear speed of the feeding roller to achieve direct and stepless adjustment of the strip conveying power. The encoder is integrated with the servo motor, with a resolution of no less than 10,000 pulses / revolution, used to collect the angular displacement information of the motor rotor in real time and feed it back to the central control unit, forming a high-precision closed-loop speed control system to ensure the dynamic response accuracy and stability of the feeding speed.

[0022] The speed sensor is a non-contact photoelectric encoder or magnetic speed sensor, directly installed on the drive shaft end of the main working roller of the leveling machine. It is used to collect the linear speed signal of the leveling roller in real time and use this signal as a reference value for speed synchronization. The central control unit receives the actual linear speed of the feeding roller fed by the encoder and the linear speed of the leveling machine working roller collected by the speed sensor in real time. It calculates the speed deviation between the two through a PID control algorithm and dynamically adjusts the output speed of the servo motor to control the synchronization error between the feeding speed and the leveling speed within ±0.5%.

[0023] In addition, during the start-up, shutdown, or speed change of the leveling machine, the central control unit calls the S-curve acceleration and deceleration algorithm to generate a smooth speed change curve, and controls the servo motor to gradually increase or decrease speed according to the preset acceleration curve, so as to avoid the inertial impact, tension oscillation, or local stretching / accumulation of the strip caused by sudden speed changes, and further ensure the stability of the feeding process and the integrity of the material.

[0024] Step 3: The material condition detection module includes at least three sets of laser displacement sensors arranged along the feeding channel to monitor the strip sag and lateral offset; In this embodiment, the material condition detection module includes at least three sets of laser displacement sensors arranged longitudinally along the feeding channel. Each set of sensors adopts a dual-channel or multi-channel laser ranging structure, which can simultaneously collect the sag deformation of the strip in the vertical direction and the offset displacement in the transverse direction.

[0025] The laser displacement sensor is a non-contact structure, installed on fixed brackets on both sides and above the feeding channel. Its laser emitter and receiver are configured in a face-to-face or reflective manner. The working wavelength is 650nm or 850nm infrared laser, the measurement accuracy is better than ±5μm, and the sampling frequency is not less than 500Hz, ensuring that real-time deformation data can be stably acquired even when the strip is running at high speed, up to 120m / min.

[0026] The three sets of sensors are distributed sequentially along the running direction of the strip: the first set is located 500mm after the exit of the uncoiler and is used to monitor the sag fluctuation in the initial tension transition zone; the second set is located 300mm before the entrance of the leveler and serves as the final shape monitoring point before entering the leveling roller; the third set is located between the two sets of feeding rollers and is used to detect local sagging or wave deformation caused by insufficient support or uneven tension in the middle section.

[0027] Each sensor group is equipped with an independent signal processing unit, which outputs the vertical distance between the upper and lower edges of the strip in real time to calculate the sag and the lateral offset of the strip centerline relative to the preset baseline, in mm, and uploads the data to the central control unit.

[0028] When any sensor detects that the sag exceeds the preset safety threshold, such as ≥3mm or the lateral offset exceeds ±5mm, the central control unit immediately triggers a graded intervention strategy: it prioritizes reducing the feeding speed and fine-tuning the uncoiling tension. If it does not recover within 2 seconds, it links the leveling machine to reduce its speed to prevent the strip from being squeezed, folded or locally piled up before the leveling roll gap, thus avoiding indentation defects caused by abnormal shape from the source.

[0029] Through this multi-point, synchronous, and dual-dimensional spatial monitoring architecture, the system realizes dynamic three-dimensional morphology perception of strip steel throughout the entire conveying process. In particular, it effectively suppresses sudden surface defects caused by the failure to detect local deformation in traditional systems during high-speed continuous production, providing direct data support for achieving a finished product indentation defect rate of less than 0.1%.

[0030] Step 4: The central control unit receives signals from each sensor, calculates the tension difference in real time and adjusts the uncoiling speed. The PID algorithm controls the synchronization error between the feeding speed and the leveling speed to be ≤±0.5%. When any laser sensor detects that the sag exceeds the limit, it performs active intervention by deceleration and tension fine-tuning to prevent the strip from being squeezed and piled up before entering the leveling roller. In this embodiment, the central control unit is an industrial-grade PLC or an embedded industrial control computer, equipped with a real-time multi-tasking operating system and a high-speed data acquisition interface. Its input ports are respectively connected to a first tension sensor, a second tension sensor, an encoder, a speed sensor, and at least three sets of laser displacement sensors, forming a four-dimensional synchronous sensing system for uncoiling tension, feeding speed, leveling speed, and strip shape.

[0031] The central control unit has multiple preset control algorithm modules that run in parallel according to priority, specifically including: 1. Tension difference closed-loop adjustment module: The dynamic sampling data of the first tension sensor F1 and the second tension sensor F2 are read in real time, and the tension difference ΔF = F2 – F1 is calculated. When ΔF ≥ 0, it is determined that the tension at the leveling end is sufficient or there is a stretching tendency. The uncoiling servo drive device is controlled to accelerate appropriately to alleviate the tension accumulation of the strip in the feeding channel. When ΔF ≤ 0, it is determined that the tension at the leveling end is insufficient or there is a risk of loose accumulation. The uncoiling servo drive device is controlled to decelerate appropriately to eliminate local bending and interlayer misalignment of the strip in the channel. The control cycle is ≤10ms and the sampling frequency is ≥100Hz, ensuring a rapid response to transient tension fluctuations.

[0032] 2. Speed ​​synchronization PID control module: Based on the actual linear speed of the feed roller fed by the encoder feedback and the linear speed of the leveler working roller collected by the speed sensor, the speed deviation e(t) = V_leveling – V_feeding is constructed. An improved PID controller is adopted with a proportional gain Kp=1.2, integral time Ti=0.8s, and derivative time Td=0.1s. It outputs speed compensation commands in real time to drive the feeding servo motor to dynamically correct the operating parameters, so that the synchronization error between the feeding speed and the leveling speed is continuously stable within ±0.5%, which is significantly better than the error level of more than ±3% of the traditional open-loop system.

[0033] 3. Active intervention module for morphological abnormalities: When any set of laser displacement sensors detects that the strip sag exceeds a preset threshold, such as ≥3mm or the lateral offset exceeds ±5mm, the system immediately activates a graded response strategy: Level 1: Automatically triggers the feeding servo motor to decelerate by 10%~20% within 0.1 seconds; Second stage: Synchronously adjust the uncoiling servo drive device and fine-tune the tension setting value by ±5%~10% to restore the strip to a straight state; Level 3: If the above intervention fails to restore the sag or offset to the safe range within 2 seconds, the main shaft of the leveling machine will be forcibly decelerated, with a deceleration of ≤15%, and an audible and visual alarm signal will be output, while the event log will be recorded. This intervention mechanism is continuously effective within 200mm before the strip enters the leveling roll, effectively avoiding "clamping and squeezing" and "interlayer friction" caused by abnormal shape, thus eliminating the generation of indentation defects from the source.

[0034] 4. Parameter adaptive configuration module: The central control unit has an embedded database of steel coil thickness parameters, which pre-stores multiple sets of standard process parameters with a thickness range of 0.3mm to 3.0mm, including: feed roller gap, pressure arm pressure, tension reference value, sag safety threshold and S-curve acceleration and deceleration slope; After the operator inputs the current steel coil thickness through the human-machine interface, the system automatically retrieves and loads the corresponding parameter group, completing the one-click configuration of all channels of controller parameters. This eliminates the need for repeated manual adjustments, significantly shortens changeover time, and prevents material damage caused by incorrect parameter settings.

[0035] During the start-up, shutdown, or speed change of the leveling machine, the central control unit uses a five-segment S-curve acceleration / deceleration algorithm to plan the trajectory of the feeding servo motor, achieving continuous and stepless transition of the feeding speed. This algorithm achieves smooth changes in the speed curve by controlling the jerk—the rate of change of acceleration—limiting the maximum jerk to ≤5m / s³, ensuring that the fluctuation amplitude of the inertial force on the strip is reduced by more than 80%, and avoiding local stretching, wrinkling, or relaxation impact caused by sudden acceleration changes.

[0036] Meanwhile, the system controls the transition time of the entire acceleration / deceleration process to within ≤0.5 seconds, balancing response speed and material stability. For example, when the feeding speed accelerates from 0 to 80 m / min (approximately 1.33 m / s), the system completes the entire transition within 0.5 seconds, with the peak acceleration not exceeding 2.67 m / s², far lower than the impact level caused by traditional trapezoidal curves, which typically result in ≥5 m / s².

[0037] The S-curve trajectory operates in conjunction with the PID speed synchronization control module: During the transition period, the central control unit dynamically corrects the target speed curve of the feeding servo motor in real time based on the feedback signal from the speed sensor of the leveling machine's working roller, so that the synchronization error between the feeding speed and the leveling speed is always maintained within ±0.5%, avoiding strip jitter, edge wrinkles or local accumulation caused by asynchronous speeds in the transition section.

[0038] By applying the technical solution of this embodiment, a first tension sensor and a second tension sensor are installed between the uncoiler outlet and the leveler inlet to collect the tension values ​​of the strip at different positions in real time. The central control unit calculates the tension difference and dynamically adjusts the speed of the uncoiler servo drive device, effectively eliminating strip stretching or slack caused by tension imbalance during feeding and leveling. At the same time, a closed-loop feedback system is constructed using the servo motor and encoder of the drive feed roller and the linear speed sensor of the leveler work roller. The PID algorithm precisely controls the synchronization error between the feeding speed and the leveling speed to not exceed ±0.5%, ensuring that the strip maintains a stable speed match during the conveying process, fundamentally avoiding accumulation or breakage caused by speed asynchrony. In addition, at least three sets of laser displacement sensors are arranged along the feeding channel to continuously monitor the sag and lateral offset of the strip. When any sensor detects a risk of sag exceeding the limit, the central control unit immediately triggers an active intervention mechanism of deceleration and tension fine-tuning, eliminating the sag deformation and local extrusion tendency in time before the strip enters the leveling roller, thereby preventing the material from accumulating, twisting or jamming when entering the work roller area. In summary, this solution achieves three major functions in synergy: tension stabilization, speed synchronization, and active protection of material condition. It effectively solves the technical problems in existing technologies, such as asynchronous feeding speed and leveling speed, severe fluctuations in strip tension, and extrusion and accumulation before entering the leveling rollers. This significantly improves leveling quality and production continuity, and ensures the safe and efficient operation of the equipment.

[0039] Example 1: In this example, the central control unit controls the uncoiler to accelerate or decelerate according to the positive or negative direction of the tension difference ΔF between the first tension sensor and the second tension sensor: when ΔF ≥ 0, the uncoiler is accelerated to relieve tension, and when ΔF ≤ 0, the uncoiler is decelerated to eliminate accumulation.

[0040] In this embodiment, the central control unit further constructs a bidirectional closed-loop control logic with the tension difference ΔF = F2 – F1 as input based on the real-time tension signals collected by the first tension sensor and the second tension sensor, where F1 is the tension at the uncoiling machine outlet and F2 is the tension at the leveling machine inlet.

[0041] When ΔF ≥ 0, it indicates that the inlet tension of the leveler is not lower than the outlet tension of the uncoiler. The system determines that the strip is in a tensile-dominated state in the feeding channel, and there is a risk of material plastic deformation or strip breakage. At this time, the central control unit immediately outputs an acceleration command to drive the uncoiler servo drive device to increase the feeding speed and actively increase the feeding amount to reduce the tension difference and release local tensile stress, so as to achieve "increased supply and slowed stretching".

[0042] When ΔF ≤ 0, it indicates that the inlet tension of the leveler is lower than the outlet tension of the uncoiler. The system determines that there is a lack of tension in the feeding channel, the strip is loose, or there is a tendency for local accumulation. At this time, the central control unit outputs a deceleration command to reduce the uncoiling speed of the uncoiler, so that the feeding rate and the leveling traction rate are rematched, and actively eliminates strip wrinkles, interlayer misalignment, or front-end accumulation caused by speed mismatch.

[0043] This bidirectional response mechanism based on the ΔF sign criterion differs from traditional systems that rely solely on fixed tension settings or hysteresis feedback in open-loop control. It achieves precise identification and directional intervention of the direction of tension imbalance. With a control response period of ≤10ms, it works in conjunction with the PID speed synchronization module, enabling directional, dynamic, and anti-interference adjustment of the uncoiling speed. This effectively avoids failure modes such as strip breakage, wrinkling, or feed accumulation caused by tension fluctuations, significantly improving the stability and continuity of material conveying at the leveling inlet, laying the foundation for subsequent high-precision leveling operations.

[0044] Example 2: In this example, the central control unit uses an S-curve acceleration / deceleration algorithm to control the feed roller speed smoothly during the start-up, shutdown, or speed change phases of the leveling machine, thus avoiding material impact caused by sudden speed changes.

[0045] In this embodiment, the central control unit uses a five-segment S-curve acceleration and deceleration algorithm to plan the speed trajectory of the AC servo motor driving the feeding roller under dynamic conditions such as start-up, stop, acceleration, deceleration or specification switching of the leveling machine, so as to achieve continuous and stepless transition of feeding speed.

[0046] The S-curve algorithm divides the velocity change process into: acceleration phase (Jerk rises) → constant acceleration phase → deceleration phase (Jerk falls) → uniform speed phase → deceleration phase (Jerk reverses) → constant deceleration phase → deceleration phase (Jerk rises back to zero). By controlling the temporal change of the acceleration Jerk, the velocity curve is made into a smooth "S" shape, and the rate of acceleration change is controlled at ≤5 m / s³, ensuring that the fluctuation amplitude of the inertial force on the strip is reduced by more than 80%, fundamentally eliminating the instantaneous stretching or relaxation impact caused by sudden acceleration changes in the traditional trapezoidal acceleration and deceleration method.

[0047] The speed planning command works in conjunction with the aforementioned PID speed synchronization control module: during the S-curve transition, the central control unit dynamically corrects the target speed curve of the feeding servo motor in real time based on the feedback signal from the speed sensor of the leveling machine's working roller, so that the synchronization error between the feeding speed and the leveling speed is always kept within ±0.5%, avoiding strip jitter, edge wrinkles or local accumulation caused by asynchronous speeds in the transition section.

[0048] Especially during the process of leveling machine starting from zero speed to rated speed, such as 60m / min or changing multiple specifications of steel coils, S-curve control reduces the strip tension fluctuation range from ±15% in the traditional method to ≤±3%, and there are no visible scratches, indentations or wave deformations on the material surface, which significantly improves the process stability and product yield during high-speed start-up and shutdown.

[0049] This technical solution differs from existing technologies that only use fixed acceleration / deceleration slopes or open-loop speed settings. It achieves a three-in-one approach to speed control under dynamic operating conditions, integrating smoothness, synchronization, and disturbance resistance, providing key support for the continuous and defect-free production of high-surface-quality steel coils, such as automotive steel sheets and home appliance panels.

[0050] Example 3: In this example, the laser displacement sensor is a multi-point lateral scanning structure that can simultaneously detect the strip sag and lateral offset. When the offset exceeds a preset threshold, an alarm or correction command is triggered.

[0051] In this embodiment, the laser displacement sensor is a multi-point lateral scanning structure. Each sensor group integrates two independent laser ranging channels: one channel projects vertically downwards to measure the vertical distance from the upper surface of the strip to the sensor reference surface, thereby calculating the sag of the strip at each longitudinal section, i.e., the maximum and minimum height difference; the other channel moves laterally along the width direction of the strip, using a high-speed galvanometer or linear sliding mechanism to drive the laser beam to perform multi-point sampling at a frequency of ≥200Hz within a width range of 50~200mm, to obtain the lateral offset between the edge of the strip and the preset center reference line.

[0052] This structure enables synchronous, heterogeneous, and homogeneous acquisition of sag and lateral offset. After the data is fused and processed by the internal DSP processor, it outputs real-time digital signals of the strip centerline offset ΔX (in mm) and local sag ΔZ (in mm), which are then transmitted to the central control unit.

[0053] When any sensor detects a lateral offset ΔX exceeding a preset safety threshold, preferably ±5mm, the central control unit immediately triggers a lateral correction command: If the offset direction is positive to the right, the output signal drives the pneumatic or servo correction roller group installed on the side wall of the feeding channel to move slightly to the left to compensate for the strip displacement. If the offset direction is negative to the left, then the correction mechanism is driven to the right; The correction action amplitude is linearly adjusted by the offset amount. For every 1mm increase in ΔX, the correction amount increases by 0.2~0.5mm, and the response time is ≤50ms, ensuring dynamic stability under the condition that the strip travel speed is ≤120m / min.

[0054] At the same time, while triggering the correction, the system simultaneously records the event log, including timestamp, offset value, actuator action, and residual error after correction. It also issues a yellow flashing alarm signal through the human-machine interface to remind operators to pay attention to the quality of incoming materials or the status of the guiding device.

[0055] This active detection and closed-loop correction mechanism for lateral offset works in conjunction with the aforementioned sag over-limit intervention strategy to form a comprehensive dynamic control capability for the "three-dimensional spatial posture" of the strip steel, namely longitudinal sag + lateral offset + axial velocity. This completely solves the problem of hidden defects such as "slant pulling", "twisting" and "edge curling" that occur in the leveling roll gap of traditional systems because they only monitor sag and ignore lateral drift. This provides a key guarantee for achieving a surface indentation defect rate of ≤0.1% for finished products.

[0056] Example 4: In this example, the central control unit pre-stores standard parameter sets corresponding to steel coils of different thicknesses, including feeding gap, pressing pressure, tension threshold and sag safety threshold. After the operator inputs the thickness, the system automatically calls up and configures the parameters.

[0057] In this embodiment, the central control unit has a pre-installed database of steel coil thickness parameters. This database stores multiple standard process parameter groups indexed by steel coil thickness. Each parameter group contains the following four categories of key control parameters: Feeding gap: refers to the opening distance between the upper and lower rollers of the feeding roller group, covering a steel coil thickness of 0.3mm to 3.0mm. The corresponding gap value is set linearly according to 1:1.2 times the thickness. For example, a 0.5mm steel coil corresponds to a 0.6mm gap. Clamping pressure: refers to the positive pressure applied by the clamping arm to the upper surface of the strip. Based on the non-linear matching of the material yield strength and thickness, the range is set to 20N~200N. The greater the thickness, the higher the clamping force to suppress vibration. Tension threshold: including the upper and lower limits of uncoiling tension, used to limit the target adjustment range of the uncoiling servo drive device, such as F1∈[80N, 130N] and F2∈[75N, 125N] for 0.8mm steel coil; Sag safety threshold: This is the critical value of vertical deformation that triggers the intervention of the laser sensor. It is set according to the thickness ratio. For example, the threshold is 3mm for steel coils ≤1.0mm and 4mm for steel coils >1.0mm, to prevent thick plates from being falsely triggered due to their high rigidity.

[0058] When the operator inputs the current steel coil thickness through a human-machine interface, such as a touchscreen (which supports manual input or barcode scanning), the central control unit automatically retrieves and matches the closest set of standard parameters to complete the following four-channel one-click configuration: Adjust the gap between the feed rollers to the corresponding value, and drive the pneumatic or electric actuator to move to the target position; Set the target output value of the servo pressure controller of the pressing device; Lock the ΔF adjustment reference range of the unwinding tension control module; Enable the sag alarm threshold and lateral offset judgment criteria for the laser displacement sensor.

[0059] After the parameters are configured, the system automatically activates the unwinding tension closed-loop control, feeding speed PID synchronous control and material morphology monitoring modules. Based on the real-time data of the aforementioned sensors, the unwinding speed, feeding speed and tension settings are dynamically corrected to ensure that the synchronization error is always ≤±0.5% and the sag does not exceed the limit during actual operation.

[0060] This parameter adaptive mechanism completely replaces the traditional "trial and error" manual debugging mode, reducing the changeover time from an average of 15-30 minutes to ≤90 seconds. It eliminates initial defects such as "indentation", "tears" and "feed accumulation" in strip steel caused by incorrect parameter settings. It is especially suitable for continuous production scenarios of high-end sheet metal with multiple varieties and small batches, such as automotive outer panels and home appliance panels, significantly improving the flexibility and yield stability of the production line.

[0061] Example 5: In this example, when the laser sensor detects that the sag exceeds the limit, the central control unit performs intervention according to the graded strategy: first, the feeding speed is reduced, and then the unwinding tension is finely adjusted; if it does not recover within 2 seconds, the leveling machine is triggered to reduce its speed.

[0062] In this embodiment, when any laser displacement sensor detects that the strip sag exceeds a preset safety threshold, such as ≥3mm, the central control unit immediately activates a three-level progressive active intervention strategy, executing the following actions sequentially according to time sequence and control priority: Level 1 intervention is triggered within 0–0.5 seconds: The central control unit outputs a deceleration command to the feeding servo motor, reducing the feeding speed by 10%–20% to slow down the feed rate of the strip before it enters the leveler, thus mitigating the tendency for local accumulation and interlayer compression caused by excessive sag. The response time of this action is ≤100ms, which does not affect the operation of the leveler spindle, and prioritizes controlling the deterioration of the shape by "reducing input".

[0063] Level 2 intervention is triggered within 0.5–1.5 seconds: If the sag does not recover to below the threshold within 1.5 seconds after the first-level intervention, the central control unit simultaneously activates the uncoiling tension fine-tuning mechanism: based on the real-time tension difference ΔF = F2 – F1, the output torque of the uncoiling servo drive is dynamically adjusted, and the uncoiling tension setting is slightly adjusted within the original reference range of ±5%–10%. If ΔF≤0, the tension is increased first to straighten the strip; if ΔF>0, the tension is appropriately reduced to release local stress, achieving closed-loop correction of the "tension adaptation form".

[0064] Level 3 intervention is triggered within 1.5–3.5 seconds: If the above two levels of intervention fail to restore the sag to a safe range within a cumulative 2 seconds, i.e. the duration of exceeding the limit is ≥2s, the central control unit determines that the system is in a high-risk state and immediately sends a speed reduction command to the main drive system of the leveling machine to reduce the linear speed of the leveling work roller by 5%–15%, thereby reducing the material input rate from the terminal stage and forming a three-level collaborative compensation chain of "feeding deceleration → tension fine adjustment → leveling speed reduction".

[0065] This tiered intervention strategy has a dual mechanism of time-sequence locking and condition triggering: each action level must meet the dual conditions of "duration" and "state not recovered" before it can be upgraded, avoiding accidental triggering due to transient fluctuations; at the same time, each level of action is logged independently, including trigger time, action type, execution range, and recovery status, and uploaded to the human-machine interface in a synchronized manner, supporting operators to trace back and optimize the process afterward.

[0066] This strategy differs from the passive response method of traditional systems that only use a single deceleration or fixed tension setting. Through a progressive control logic of "first slowing down, then adjusting the force, and finally reducing the speed", it significantly improves the system's adaptability to complex deformations, such as local bending, material unevenness, and incoming material fluctuations, without adding sensors or actuators. It effectively prevents failure modes such as "folding and stacking", "interlayer slippage", and "indentation defects" from occurring in the strip before it enters the leveling roll, providing key control assurance for achieving an indentation defect rate of ≤0.1% on the finished product surface.

[0067] Example 6: In this example, the first and second tension sensors are contact tension detection rollers with a sampling frequency ≥100Hz and strain gauge sensing elements to ensure stable acquisition of dynamic tension signals.

[0068] In this embodiment, both the first tension sensor and the second tension sensor adopt a contact tension detection roller structure. The main body is a hollow alloy roller body, the surface of which is polished and coated with a high friction coefficient polyurethane coating to ensure stable contact with the strip surface without damaging the material. At least four strain gauge sensing elements are embedded inside the roller body in a 90° symmetrical distribution. The patch direction is arranged crosswise along the axial and circumferential directions of the roller body to eliminate measurement errors caused by off-center loading. This forms a full-bridge Wheatstone bridge circuit to achieve high-precision conversion of the radial pressure applied to the roller body when the strip passes through.

[0069] The signal conditioning circuit of the sensor module is integrated inside the end cover of the roll body. It adopts a 24-bit high-resolution ADC analog-to-digital converter with a sampling frequency ≥100Hz and a response bandwidth ≥50Hz. It can stably capture transient tension changes caused by sudden tension changes, vibration or material thickness fluctuations in strip steel under high-speed operation of up to 120m / min. The dynamic sampling error is ≤±0.5%FS.

[0070] The tension signal, after filtering, temperature compensation, and linear correction, is uploaded to the central control unit in real-time data stream form, serving as the core input source for calculating ΔF = F2 – F1 and adjusting the uncoiling speed. During the start-up, shutdown, acceleration, or speed change of the uncoiler, the tension oscillation frequency caused by the inertia of the strip can reach 20–40Hz. Traditional non-contact tension gauges often lose key fluctuation information due to response delays. However, the contact strain gauge sensor used in this solution achieves millisecond-level physical response because it directly couples with the mechanical load, ensuring that the PID control module always performs closed-loop adjustment based on real, distortion-free tension data, thus keeping the synchronization error between the feeding speed and the leveling speed stably within ±0.5%.

[0071] In addition, the high-precision tension signal also provides a reliable basis for the "graded intervention strategy" described in claim 6: when the laser sensor detects that the sag exceeds the limit, the central control unit accurately judges whether it is "excessive material supply leading to loose accumulation" (ΔF≤0) or "excessive traction causing stretching" (ΔF≥0) based on the real-time ΔF value, thereby deciding whether to decelerate and unwind or fine-tune the tension to avoid misjudgment and secondary impact.

[0072] This structure and configuration are significantly superior to the photoelectric tension gauges or non-contact pneumatic tension sensing devices used in the prior art. It solves the problem of tension mismeasurement caused by signal lag, environmental interference, and surface reflection, and provides a physical layer reliability guarantee for the dynamic stability and high-precision collaborative control of the entire leveling and feeding process.

[0073] Example 7: In this example, the servo motor is an AC servo motor, and the encoder resolution is ≥10000 pulses / revolution, forming a high-precision closed-loop speed control system.

[0074] In this embodiment, the servo motor driving the feed roller is an AC servo motor. Its rated power is selected based on the maximum running speed of the strip steel ≤120m / min and the load inertia. It has high dynamic response characteristics and zero-speed full torque output capability, and is suitable for frequent start-stop and speed change conditions.

[0075] The AC servo motor is coaxially mounted with a high-resolution rotary transformer encoder. The encoder resolution is no less than 10,000 pulses / revolution, meaning it outputs 10,000 position pulses per revolution. Converted to the linear speed of the feed roller with a diameter of φ150mm, its position resolution can reach approximately 0.0047 mm / pulse, corresponding to a speed resolution of ≤0.002% of the rated speed. Taking 100m / min as an example, the speed resolution reaches 0.002 m / min, far exceeding traditional stepper motors or encoder systems with ≤5000 pulses / revolution.

[0076] The central control unit reads the motor angle and speed information fed back by the encoder in real time through a high-speed communication interface, such as EtherCAT or CANopen. Combined with the linear speed reference signal output by the speed sensor installed at the end of the working roller shaft of the leveling machine, a "dual closed-loop" speed control system is constructed. The inner loop consists of the current loop and speed loop inside the servo driver, which achieves microsecond-level motor response based on encoder feedback; The outer loop is the PID synchronous control loop of the central control unit. Taking the leveling roller linear speed as a reference, it calculates the feed roller speed deviation e(t) = V_leveling – V_feeding, and outputs speed compensation commands to dynamically correct the target speed of the servo motor.

[0077] In this system, because the encoder resolution is ≥10000 pulses / revolution, speed sampling jitter is effectively suppressed, and the speed fluctuation amplitude is reduced from ±1.5% in the traditional system to ≤±0.3%. This provides a stable and non-jumping input source for the PID control algorithm, ensuring that the synchronization error between the feeding speed and the leveling speed is continuously and stably controlled within ±0.5%, and providing high-precision execution guarantee for smooth trajectory tracking during the S-curve acceleration and deceleration phases.

[0078] This high-precision closed-loop structure differs from existing technologies that use low-resolution incremental encoders or open-loop frequency conversion drives. It completely solves problems such as "intermittent synchronization deviation," "speed oscillation," and "feeding pulsation" caused by insufficient speed feedback resolution, sampling delay, or pulse loss. It significantly improves the stability of strip steel during high-speed operation and avoids tensile fatigue, edge wrinkles, and inlet accumulation caused by speed asynchrony. It is the key technical foundation for achieving a finished product surface indentation defect rate of ≤0.1%.

[0079] Example 8: In this example, the central control unit is an industrial PLC or an embedded industrial computer, equipped with a human-machine interface, which supports parameter setting, status monitoring, historical data storage and communication with the MES system.

[0080] In this embodiment, the central control unit uses an industrial-grade programmable logic controller (PLC) or an embedded industrial computer based on the ARM Cortex-A series as the core controller. Its operating environment meets the IEC 61131-3 standard, has real-time multi-task scheduling capability, and a control cycle of ≤10ms, ensuring that all sensor data acquisition, tension difference calculation, PID adjustment, S-curve planning and hierarchical intervention strategies are executed synchronously under a unified time reference.

[0081] This control unit is equipped with a 7-inch or larger color touchscreen HMI, supports Chinese / English bilingual operation interface, and has the following functions: Parameter setting: Operators can manually input key process parameters such as steel coil thickness, tension threshold, sag safety range, PID parameter group, and S-curve acceleration / deceleration slope through a graphical menu, and parameters can be saved as configuration files in .cfg format; Status monitoring: Real-time display of unwinding tension F1 / F2, feeding speed V_feeding, leveling speed V_leveling, synchronization error ΔV, sag / offset of each laser sensor, system operating mode, automatic / debugging / stop and fault alarm codes; Historical data storage: Built-in SD card or eMMC storage unit can continuously record no less than 720 hours of operating data, including timestamps, tension curves, speed curves, intervention events - including trigger type, action amplitude, recovery time, alarm logs and operator login records, supporting local export and USB copy; Communicating with the MES system: Establishing a bidirectional communication link with the factory Manufacturing Execution System (MES) via standard industrial protocols such as Modbus TCP, OPC UA, or Profinet, and actively uploading data: ▶ Current steel coil number, thickness, batch number, running time, and number of defect events; ▶ Key indicators of leveling quality, such as average synchronization error, maximum sag, and frequency of intervention; ▶ The surface quality score of each batch of finished products is based on statistical analysis of laser inspection data; Simultaneously receive the following from MES: ▶ Production plan, instructions for switching steel coil specifications ▶ Process instruction package, automatically calling parameter groups, ▶ Equipment maintenance reminders and other instructions enable a closed-loop process that goes from "order-driven → automatic parameter configuration → intelligent process control → quality data feedback".

[0082] This architecture breaks through the closed control mode of traditional leveling machines, which only have local manual operation, no data recording, and no network connectivity. For the first time, it achieves three-level integration of the control layer, human-machine interaction layer, and production management layer, solving the following problems caused by the isolated operation of the system: Relying on experience for debugging when changing models is inefficient; The quality anomaly could not be traced back to a specific batch or process parameter; The production line has a low level of automation and cannot be integrated into a smart factory system.

[0083] This solution, through data standardization, open communication protocols, and modular design, enables the system to not only meet the high-precision control requirements of a single machine, but also to expand into a core node of a high-end intelligent production line for sheet metal. It provides underlying technical support for achieving intelligent manufacturing goals such as "unmanned changeover," "quality traceability," and "predictive maintenance," significantly enhancing the industrial integration value of the equipment in high-value-added fields such as automotive sheets and home appliance panels.

[0084] Example 9: In this example, the system continuously suppresses accumulation, stretching and displacement within 200mm before the strip enters the leveling roll, reducing the surface indentation defect rate of the finished product to below 0.1%, which is suitable for continuous production scenarios with high surface quality requirements such as automotive panels and home appliance panels.

[0085] In this embodiment, the system integrates closed-loop control of uncoiling tension, PID synchronous control of feeding speed, multi-point laser displacement sensing and morphological monitoring, thickness adaptive parameter calling and dynamic intervention mechanism at the front end of the leveler, to achieve continuous, synchronous and active suppression of the three major failure modes of stacking, stretching and lateral displacement in the critical section of 200mm before the strip enters the working roll group of the leveler.

[0086] This 200mm area is defined as a "safety buffer zone before the leveling entrance," the only critical deformation-sensitive area for the strip as it transitions from a flexible conveying state to rigid flattening. Within this area, three sets of laser displacement sensors, spaced ≤50mm apart, collect real-time data on the strip's sag and lateral offset. Based on this real-time data, the central control unit, through a tiered intervention strategy, reduces the feeding speed by 10–20% and fine-tunes the uncoiling tension by ±5–10% within 10ms. Combined with an S-curve speed transition and high-precision speed synchronization error ≤±0.5%, this ensures that the strip maintains a constant speed before entering the leveling roll gap. Sag ≤ 2.5mm, below the safety threshold; Lateral offset ≤ ±3mm; Tension fluctuation ΔF ≤ ±8N; Speed ​​synchronization error ΔV ≤ ±0.3%.

[0087] In continuous production testing, taking 0.8mm thick cold-rolled automotive steel sheet as an example, with a linear speed of 80m / min and a running cycle of ≥48 hours, this system ensured that no interlayer misalignment, folding, or localized tearing occurred in the 200mm section of the strip. The finished product surface was optically scanned according to ISO 11067 standard, and the indentation defect rate was stably controlled between 0.06% and 0.09%, significantly lower than the industry average of 0.5% to 2.0%. Moreover, the defect distribution was random and did not exhibit periodic repetition, indicating that it originated from process fluctuations rather than inherent equipment defects.

[0088] The effectiveness of this technology stems directly from the synergistic effect of multiple modules focusing on the 200mm critical zone in space, achieving millisecond-level linkage response in time, and forming a closed-loop feedback chain in control. Unlike the traditional system that only detects defects after leveling the roller or relies on manual observation and adjustment, this solution achieves a fundamental technological leap from "defect processing after occurrence" to "defect elimination before occurrence".

[0089] This system is particularly suitable for continuous production scenarios with stringent requirements for surface finish and consistency, including but not limited to: High-strength steel, such as DC06 and DP980, is used for automotive exterior body panels. Home appliance panels use aluminized zinc-plated sheets and electro-galvanized sheets, such as SGCC and SECC; High-precision cold-rolled steel sheets are used for metal structural components in smart homes.

[0090] Its stable output of ≤0.1% indentation defect rate has been confirmed by third-party testing agencies such as SGS and TÜV in customer production line verification reports, providing a reliable technical guarantee for the stable mass production of high value-added sheet materials.

[0091] Obviously, those skilled in the art should understand that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous feeding control system for a steel coil leveling machine, characterized in that, include: The system comprises an uncoiling tension control module, a feeding speed synchronization module, a material condition detection module, and a central control unit. The uncoiling tension control module includes a first tension sensor located at the uncoiler outlet, a second tension sensor located at the leveler inlet, and a servo drive device for adjusting the uncoiling speed. The feeding speed synchronization module includes a servo motor driving the feeding roller, an encoder connected to it, and a speed sensor for detecting the linear speed of the leveler's working roller. The material condition detection module includes at least three sets of laser displacement sensors arranged along the feeding channel to monitor strip sag and lateral offset. The central control unit receives signals from each sensor, calculates the tension difference in real time, and adjusts the uncoiling speed. A PID algorithm is used to control the synchronization error between the feeding speed and the leveling speed to ≤±0.5%. When any laser sensor detects excessive sag, proactive intervention with deceleration and tension fine-tuning is implemented to prevent strip from being squeezed and accumulated before entering the leveling roller.

2. The continuous feeding control system for a steel coil leveling machine according to claim 1, characterized in that, The central control unit controls the uncoiler to accelerate or decelerate according to the positive or negative direction of the tension difference ΔF between the first tension sensor and the second tension sensor: when ΔF ≥ 0, the uncoiler is accelerated to relieve tension, and when ΔF ≤ 0, the uncoiler is decelerated to eliminate accumulation.

3. A continuous feeding control system for a steel coil leveling machine according to claim 1 or 2, characterized in that, During the start-up, shutdown, or speed change phases of the leveling machine, the central control unit uses an S-curve acceleration / deceleration algorithm to control the smooth transition of the feeding roller speed, wherein the acceleration does not exceed 5 m / s³ and the speed transition time does not exceed 0.5 seconds.

4. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 3, characterized in that, The laser displacement sensor has a multi-point lateral scanning structure, which can simultaneously detect the strip sag and lateral offset. When the offset exceeds a preset threshold, an alarm or correction command is triggered.

5. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 4, characterized in that, The central control unit has pre-stored standard parameter sets corresponding to steel coils of different thicknesses, including feeding gap, pressing pressure, tension threshold and sag safety threshold. After the operator inputs the thickness, the system automatically calls up and configures the parameters.

6. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 5, characterized in that, When the laser sensor detects that the sag exceeds the limit, the central control unit intervenes according to a graded strategy: first, it reduces the feeding speed, and then it fine-tunes the unwinding tension; if it does not recover within 2 seconds, it triggers the leveler to run at a reduced speed.

7. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 6, characterized in that, The first and second tension sensors are contact tension detection rollers with a sampling frequency of ≥100Hz and use strain gauge sensing elements to ensure stable acquisition of dynamic tension signals.

8. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 7, characterized in that, The servo motor is an AC servo motor, and the encoder resolution is ≥10000 pulses / revolution, forming a high-precision closed-loop speed control system.

9. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 8, characterized in that, The central control unit is an industrial PLC or embedded industrial computer, equipped with a human-machine interface, and supports parameter setting, status monitoring, historical data storage and communication with the MES system.

10. A continuous feeding control system for a steel coil leveling machine according to any one of claims 1 to 9, characterized in that, The system continuously suppresses accumulation, stretching, and displacement of the strip within 200mm before it enters the leveling roll, reducing the surface indentation defect rate of the finished product to below 0.1%. It is suitable for continuous production scenarios with high surface quality requirements, such as automotive panels and home appliance panels.

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