Control implementation method for cold rolling stability

Abstract

The invention provides a cold rolling stability control implementation method, which comprises the following steps of: after position or pressure information detected by a rolling mill sensor is obtained, determining a preliminary output signal of a rolling mill control servo valve; and then the working mode of the rolling mill is detected, if the rolling mill is in the rolling mode, amplitude limiting is conducted on the initial output signal of the rolling mill control servo valve based on a first preset amplitude limiting value, and if the rolling mill is in the roller changing mode, amplitude limiting is conducted on the initial output signal of the rolling mill control servo valve based on a second preset amplitude limiting value. And controlling a rolling mill control hydraulic cylinder based on a final output signal of the rolling mill control servo valve after amplitude limiting. In the scheme, the output signal of the rolling mill control servo valve is subjected to amplitude limiting based on the preset amplitude limiting value, and the problem of system oscillation caused by instability of the output signal due to contamination of the rolling mill sensor can be avoided. In addition, the corresponding amplitude limiting value is adopted for amplitude limiting in combination with the working mode of the rolling mill, and the actual process scene is more consistent.

Description

Technical Field

[0001] The present invention relates to the field of automatic control technology, and in particular to a method for controlling cold rolling stability. Background Art

[0002] The Pickling and Tandem Cold Mill (PL-TCM) combines pickling and tandem cold rolling processes. Through the coordinated action of a series of mechanical and automated equipment, it achieves surface treatment and thickness and shape control of the strip, ultimately producing cold-rolled strip with high precision and surface quality.

[0003] The rolling mill control system is one of the core systems in the pickling mill group. The rolling mill control system includes a rolling mill control hydraulic cylinder and a sensor for detecting the pressure and displacement of the rolling mill control hydraulic cylinder. Based on the position or pressure feedback of the sensor, closed-loop control of the position or pressure of the rolling mill control hydraulic cylinder is realized, thereby performing rolling that meets the requirements on the material.

[0004] However, in actual scenarios, due to the harsh environment inside the unit, the sensors installed in the unit are easily affected by water vapor, etc., which leads to unstable output signals of the sensors, which may cause oscillation of the entire closed-loop control system and ultimately affect the rolling results. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a method for controlling cold rolling stability to avoid problems such as system oscillation.

[0006] In a first aspect, the present invention provides a method for controlling cold rolling stability, which is used for controlling a pickling mill group, wherein the pickling mill group includes a rolling mill system and a rolling mill control system, wherein the rolling mill system includes a rolling mill, and the rolling mill control system includes a rolling mill control hydraulic cylinder, a rolling mill sensor, and a rolling mill control servo valve. The method comprises:

[0007] obtaining position or pressure information detected by the rolling mill sensor during operation of the rolling mill, and determining a preliminary output signal of the rolling mill control servo valve based on the position or pressure information;

[0008] detecting an operating mode of the rolling mill, selecting a first preset amplitude limit value when the rolling mill is in a rolling mode, and performing amplitude limiting processing on a preliminary output signal of the rolling mill control servo valve based on the first preset amplitude limit value;

[0009] When the rolling mill is in a roll changing mode, selecting a second preset amplitude limit value, and performing amplitude limiting processing on a preliminary output signal of the rolling mill control servo valve based on the second preset amplitude limit value;

[0010] The rolling mill control hydraulic cylinder is controlled based on the final output signal of the rolling mill control servo valve after the limiting process.

[0011] In an optional embodiment, the step of controlling the rolling mill control hydraulic cylinder includes:

[0012] When the rolling mill is in a rolling mode and has not passed through a strip weld, controlling the rolling mill control hydraulic cylinder in a PID adjustment mode with a first set gain coefficient and a first set integral time;

[0013] When the rolling mill is in rolling mode and passes through a strip weld, the rolling mill control hydraulic cylinder is controlled in a PID adjustment mode with a second set gain coefficient and a second set integral time;

[0014] The second set gain coefficient is smaller than the first set gain coefficient, and the second set integration time is larger than the first set integration time.

[0015] In an optional embodiment, the pickling mill group further includes an outlet section system, and the rolling mill control system further includes a hydraulic station oil tank, wherein an oil level detection sensor is provided in the hydraulic station oil tank;

[0016] The method further comprises:

[0017] Obtaining the actual oil level in the oil tank of the hydraulic station detected by the oil level detection sensor, and obtaining the working status of the equipment in the outlet section system;

[0018] Whether to issue an oil leakage alarm signal is determined based on the actual oil level and the working status of the equipment in the outlet section system.

[0019] In an optional embodiment, the step of determining whether to issue an oil leakage alarm signal based on the actual oil level and the working status of the equipment in the outlet section system includes:

[0020] Calculating a difference between the actual oil level and a set oil level value, and comparing the difference with a set difference value;

[0021] When the difference is less than or equal to the set difference, it is determined that there is no need to issue an oil leakage alarm message;

[0022] When the difference is greater than the set difference, the working status of the equipment in the outlet section system is obtained, and whether to issue an oil leakage alarm is determined based on the working status.

[0023] In an optional embodiment, the step of determining whether to issue an oil leakage alarm based on the working status includes:

[0024] If the working state of the equipment in the outlet section system indicates that the equipment in the outlet section system is in an operating state, it is determined that there is no need to issue an oil leakage alarm;

[0025] If the working state of the equipment in the outlet section system indicates that the equipment in the outlet section system is in a non-operating state, it is determined that an oil leakage alarm message needs to be issued.

[0026] In an optional embodiment, the rolling mill control system includes a plurality of devices, each of the devices having a standby state and an active state, and the method further includes:

[0027] When it is detected that a device in use stops operating, the device is switched to a standby state and the downtime of the device is recorded;

[0028] Starting from the downtime, the accumulated downtime is counted, and when the accumulated downtime reaches the set duration, a switching prompt message is issued;

[0029] When a switching operation is detected, the device in standby state is controlled to be put into operation and its state is switched to the in-use state. When it is monitored that the working time of the device reaches a preset time, the accumulated inactivity time is cleared.

[0030] In an optional embodiment, the pickling mill group further includes an outlet section system, and a digital display meter provided between the rolling mill control system and the outlet section system;

[0031] The method further comprises:

[0032] The output signal of the rolling mill control system is first transmitted to the digital display meter and then transmitted to the proportional valve of the equipment in the outlet section system, so that the output signal is displayed through the digital display meter, and the proportional valve of the equipment in the outlet section system is controlled by the output signal.

[0033] The rolling mill control system further includes a wedge adjustment device located below the rolling mill, and the method further includes:

[0034] When the rolling mill switches from a roll changing mode to a rolling mode, obtaining an actual position of the wedge adjustment device at the time of switching;

[0035] When the rolling mill is in the rolling mode, the position information of the wedge adjustment device is set to the actual position.

[0036] The rolling mill system includes a plurality of rolling mills, the rolling mill control system further includes a roll gap control servo valve, a roll gap hydraulic cylinder, and a roll gap displacement sensor, and the method further includes:

[0037] The number of interference pulses occurring in the roll gap displacement sensor in a single rolling mill is accumulated to detect whether the roll gap displacement sensor is abnormal.

[0038] The present invention provides a method for implementing control of cold rolling stability. After obtaining the position or pressure information detected by the rolling mill sensor, the preliminary output signal of the rolling mill control servo valve is determined. The working mode of the rolling mill is then detected. If it is in the rolling mode, the preliminary output signal of the rolling mill control servo valve is limited based on the first preset limit value. If it is in the roll changing mode, the preliminary output signal of the rolling mill control servo valve is limited based on the second preset limit value. The rolling mill control hydraulic cylinder is controlled based on the final output signal of the rolling mill control servo valve after limiting. In this solution, the output signal of the rolling mill control servo valve is limited based on the preset limit value, which can avoid the problem of unstable output signal of the rolling mill sensor due to contamination, thereby causing system oscillation. In addition, the corresponding limit value is used for limiting in combination with the working mode of the rolling mill, which is more consistent with the actual process scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 Schematic structural diagram of a pickling mill in an embodiment of the present invention;

[0041] Figure 2 A flow chart of a method for controlling cold rolling stability provided by an embodiment of the present invention;

[0042] Figure 3 Schematic waveform diagram of the pulse signal and the sensor signal in the embodiment of the present invention;

[0043] Figure 4 This is a functional module block diagram of a device for controlling cold rolling stability provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

[0045] Please refer to Figure 1 , which is a schematic block diagram of a pickling mill in an embodiment of the present invention, includes a rolling mill system and a rolling mill control system. The rolling mill system includes a rolling mill, which specifically includes roll shifting, backup roll balancing, work roll balance bending, intermediate roll balance bending systems, and a cam control system.

[0046] The rolling mill control system includes a rolling mill control hydraulic cylinder, a rolling mill sensor and a rolling mill control servo valve. Among them, the rolling mill sensor can detect the position or pressure information of the rolling mill control hydraulic cylinder during the operation of the rolling mill, and can adjust the rolling mill control servo valve based on the position or pressure information, and then adjust the rolling mill control hydraulic cylinder to achieve rolling operations that meet the requirements.

[0047] It should be noted that, in addition to this, the pickling mill may also include other systems, such as an inlet section system, an outlet section system, etc. Each system works in coordination with each other to complete the rolling operation of the material.

[0048] The pickling mill also includes a controller (not shown in the figure), which can be connected to various components in the pickling mill through wires to achieve interaction of data and instructions.

[0049] The following, combined Figure 2 A method for controlling cold rolling stability provided by an embodiment of the present invention is described. Figure 2 1 is a flow chart of a method for controlling cold rolling stability provided by an embodiment of the present invention, the method for controlling cold rolling stability comprising the following steps:

[0050] S11, obtaining position or pressure information detected by a rolling mill sensor during operation of the rolling mill, and determining a preliminary output signal of a rolling mill control servo valve based on the position or pressure information.

[0051] S12, detecting the working mode of the rolling mill.

[0052] S13, when the rolling mill is in the rolling mode, selecting a first preset amplitude limit value, and performing amplitude limit processing on the preliminary output signal of the rolling mill control servo valve based on the first preset amplitude limit value.

[0053] S14, when the rolling mill is in the roll changing mode, selecting a second preset amplitude limit value, and performing amplitude limit processing on the preliminary output signal of the rolling mill control servo valve based on the second preset amplitude limit value.

[0054] S15, controlling the rolling mill control hydraulic cylinder based on the final output signal of the rolling mill control servo valve after the amplitude limiting process.

[0055] On the drive side of the pickling mill, a hydraulic cylinder controls the roll shifting. This cylinder drives the shifting beam and intermediate rolls via a pull rod to achieve shifting. The two intermediate rolls can be shifted simultaneously or individually, and this shifting can be accomplished under load and while rotating. When the roll system is under significant load, the roll shifting relies on emulsion lubrication.

[0056] In order to produce high-quality products, the intermediate roll stringing system works together with the roll bending system to quickly, continuously and arbitrarily change the roll gap convexity to achieve the most suitable rolling mill roll gap. When combined with the supporting control software, its ability to control plate shape is enhanced.

[0057] To ensure accurate control of intermediate roll movement during rolling, the intermediate roll shifting system utilizes closed-loop position control. Displacement sensors are installed in the intermediate roll shifting cylinders. However, due to the harsh environment within the mill, water vapor entering the displacement sensors can cause unstable output signals, including interference pulses. This can cause oscillations in the entire closed-loop control system, including oscillations in the outputs of both the upper and lower shifting servo valves. The output of the lower shifting servo valve can fluctuate between -100% and 0%, while the output of the upper shifting servo valve can fluctuate between 0% and 100%. This in turn causes violent vibrations in the hydraulic lines of both the upper and lower shifting servo valves, causing the entire mill to vibrate. This can damage the tensiometer, bend and break the magnetic scale of the mill's roll gap measurement device, produce chatter marks in the strip, and, in severe cases, break the strip.

[0058] like Figure 3 The figure schematically shows the output signal of the lower string roller position sensor containing interference pulses, the interference pulse of the lower string roller displacement sensor, the output signal of the lower string roller servo valve, and the output signal of the upper string roller displacement sensor without interference pulses, the output signal of the upper string roller servo valve, and the servo valve output oscillation pulse.

[0059] Based on this, this embodiment introduces a limiting mechanism to prevent system oscillation. Specifically, by analyzing the output signal of the rolling mill control servo valve during normal operation, a limiting step is added to the output of the rolling mill control servo valve, and the output during normal production is used as the limiting value of the limiting step.

[0060] Before adding the limiting mechanism, the output of the mill control servo valve can vary between -100% and +100%. By observing the actual mill control servo valve output, it can be found that the actual output of the mill control servo valve varies between -10% and +10% during the rolling process. During the roll changing process, since the roll stringing needs to run to the roll changing position, the servo valve output can reach -100% and +100% at the moment of roll stringing start, and then the actual output is reduced to between -30% and +30%.

[0061] Because roll-changing mode inherently introduces interference pulses, relatively large changes within a short period of time are permitted in this mode. However, when the mill is in rolling mode, strict protection against the effects of interference pulses is required. To this end, in this embodiment, a first preset amplitude limit value and a second preset amplitude limit value are pre-set for rolling mode and roll-changing mode, respectively. The first preset amplitude limit value can be, for example, -10% to +10%, and the second preset amplitude limit value can be, for example, -30% to +30%.

[0062] Therefore, during the process, the initial output signal of the mill control servo valve can be determined based on the position or pressure information detected by the mill displacement sensor in the mill's roll-shifting control hydraulic cylinder. Based on this, an appropriate limiter value is selected based on the mill's operating mode, and the initial output signal is then limited based on the limiter value. This ensures that when the mill is in rolling mode, the final output signal of the mill control servo valve is between -10% and +10%, and when the mill is in roll-changing mode, the final output signal of the mill control servo valve is between -30% and +30%.

[0063] By adding a limiting mechanism, even when the mill displacement sensor contains interference pulses, the mill servo valve output can only vary between -10% and +10% during rolling. Only during roll change mode can it briefly vary between -30% and +30%. This eliminates system vibration caused by interference pulses in the mill control hydraulic cylinder displacement sensor. With the addition of the limiting mechanism, even when the mill displacement sensor contains interference pulses, the mill control servo valve output can only vary between -10% and +10% during rolling.

[0064] In this embodiment, amplitude limiting is also implemented for other types of rolling mills in the pickling mill, including those for backup roll balancing, work roll balancing and bending, and intermediate roll balancing and bending. These mills utilize different servo valve output amplitude limiting during normal production and roll changing. A amplitude limiting program has been added to the servo valve outputs for backup roll balancing, work roll balancing and bending, and intermediate roll balancing and bending. In rolling mode, the servo valve output has a maximum negative amplitude limit of -10% and a maximum positive amplitude limit of +10%. In roll changing mode, the servo valve output has a maximum negative amplitude limit of -100% and a maximum positive amplitude limit of +100%. This reduces system vibration caused by pressure sensor damage during rolling.

[0065] The cold rolling stability control method provided in this embodiment limits the output signal of the rolling mill's control servo valve based on a preset limiter value. This prevents the problem of unstable output signals from the rolling mill's displacement sensor due to contamination, which can lead to system oscillation. Furthermore, the limiter value is used in conjunction with the mill's operating mode, making it more consistent with actual process scenarios.

[0066] To further prevent the problem of unstable output signals caused by contamination of the rolling mill roller displacement sensor, a metal jacket can be installed outside the electrical conversion part of the rolling mill roller displacement sensor and installed with a sealing ring. This can effectively reduce the ingress of water vapor and other substances into the rolling mill roller displacement sensor.

[0067] In addition, in order to intuitively display the interference to the sensor, the number of pulses can be accumulated each time an interference pulse occurs in the rolling mill displacement sensor, and then displayed on the display interface of the PLC touch device, so that the staff can detect sensor abnormalities in time.

[0068] In this embodiment, the hydraulic system is controlled based on the final output signal of the rolling mill control servo valve after the amplitude limiting process, so that the rolling mill is controlled by the hydraulic system to form a closed-loop control.

[0069] In actual scenarios, during the rolling mill control process, there may be a contradiction between control speed, accuracy and stability. In this case, product quality should be the main goal, and we should not only pursue high speed and accuracy.

[0070] Research and analysis revealed that the mill's (roller shifting) setpoints fluctuate significantly when transitioning from one coil to the next—that is, when the mill passes through a weld seam. If the roll bending and shifting systems respond too quickly when passing the weld seam, strip breakage can occur.

[0071] Based on this, in this embodiment, the step of controlling the rolling mill control hydraulic cylinder can be achieved by the following methods:

[0072] When the rolling mill is in rolling mode and has not passed the strip weld, the rolling mill control hydraulic cylinder is controlled in a PID adjustment mode with a first set gain coefficient and a first set integral time; when the rolling mill is in rolling mode and has passed the strip weld, the rolling mill control hydraulic cylinder is controlled in a PID adjustment mode with a second set gain coefficient and a second set integral time.

[0073] The hydraulic system performs control based on the PID control model, which consists of a proportional, integral, and differential component. The proportional component generates a control signal based on the current error and a proportional coefficient (gain factor), while the integral component accumulates the error over a certain period of time to generate a control signal proportional to the accumulated error.

[0074] When the mill is not passing through a strip weld, the gain coefficient can be set larger and the integral time can be set smaller for faster response. However, when the mill is passing through a strip weld, in order to meet product quality and reduce the response speed of the PID control model when the mill passes through the weld and the specifications are dynamically changed, the gain coefficient can be set smaller and the integral time can be set larger. This will improve system stability and prevent system oscillation.

[0075] Therefore, the second set gain coefficient is smaller than the first set gain coefficient, and the second set integration time is larger than the first set integration time. For example, the first set gain coefficient may be 1.5, the first set integration time may be 110 milliseconds, the second set gain coefficient may be 0.6, and the second set integration time may be 310 milliseconds.

[0076] During the operation of the pickling mill, the hydraulic system of the pickling mill often suffers from oil pipe ruptures and seal failures, resulting in oil leaks. Because the mill is operating normally and the periphery of the mill is closed when the oil leak occurs, the operator is unaware of the oil leak in the hydraulic system of the mill.

[0077] Therefore, an oil level detection sensor is usually installed in the hydraulic station tank to transmit the real-time numerical detection of the oil level in the hydraulic station tank to the control system. The control system sets an oil level alarm setting value. When an oil leakage accident occurs due to oil pipe rupture and sealing ring damage, the actual oil level is lower than the oil level alarm setting value, the control system will issue an alarm and the hydraulic station pump will be stopped.

[0078] However, if the difference between the oil tank level alarm setting and the actual oil level is significantly greater, a large volume of oil will need to leak in the event of an oil leak before the tank level drops below the alarm setting, prompting the control system to issue an alarm and shut down the hydraulic station pump, resulting in significant waste. If the difference between the oil tank level alarm setting and the actual oil level is smaller, the mill's exit system will require the mill to operate with larger cylinders, such as the walking beam at the mill's exit. Every 10 minutes or so, the exit walking beam will operate to transport the mill's rolled steel coils. This occurs with intervals of approximately 10 minutes between each movement. This will cause the tank's oil usage to be significantly higher, resulting in a transiently low oil level and a erroneous alarm from the control system and shutting down the hydraulic station pump.

[0079] In order to solve the above problems, in this embodiment, the following methods can be used to solve the problems of excessive oil leakage or false alarms:

[0080] The actual oil level in the hydraulic station tank is obtained by the oil level detection sensor, and the working status of the equipment in the outlet section system is obtained; based on the actual oil level and the working status of the equipment in the outlet section system, it is determined whether to issue an oil leakage alarm signal.

[0081] In this embodiment, the equipment in the outlet section system primarily includes devices such as a walking beam. An oil level sensor detects the actual oil level in the hydraulic station's oil tank and simultaneously obtains the operating status of the walking beam and other devices. Combining the detected actual oil level and the operating status of the walking beam and other devices, an oil leak is determined, and the decision is made whether an oil leak alarm should be issued.

[0082] In this embodiment, the step of determining whether to issue an oil leakage alarm signal based on the actual oil level and the working status of the equipment in the outlet section system can be achieved by:

[0083] Calculate the difference between the actual oil level and the set oil level value, and compare the difference with the set difference; if the difference is less than or equal to the set difference, determine that there is no need to issue an oil leak alarm; if the difference is greater than the set difference, obtain the working status of the equipment in the outlet section system, and determine whether to issue an oil leak alarm based on the working status.

[0084] In this embodiment, if the difference between the actual oil level and the set oil level value is less than or equal to the set difference, it can be indicated to a certain extent that the oil usage in the fuel tank is normal and the remaining oil amount in the fuel tank is normal. In this case, it can be determined that there is no need to issue an oil leak alarm.

[0085] If the difference between the actual oil level and the oil level setting value is greater than the set difference, it is also necessary to combine the working status of the equipment in the outlet section system to determine whether there is an oil leak.

[0086] Since the equipment in the unit continuously requires oil during startup, the oil level in the tank decreases as the startup progresses. For a period of time after startup, the oil level in the tank fluctuates. After the unit has been started and operated for a period of time and stabilized, the mill control system automatically stores the current actual tank level as the setpoint.

[0087] In this embodiment, after the unit is started and runs stably for a period of time, each preset time interval can be used as a recording period to obtain the actual oil level detected in each recording period, and the actual oil level of each recording period can be compared with the oil level set value to obtain the difference of each recording period.

[0088] For example, after the mill has been powered on and running for five minutes, and after the mill has stabilized, the mill control system automatically stores the current actual oil tank level as the set oil level. Then, every 20 seconds, as a recording period, the actual oil level after 20 seconds is compared with the set oil level to obtain the difference. If the difference is less than or equal to the set difference for that recording period, no alarm is required. However, if the difference is greater than the set difference for that recording period, it indicates a possible oil leak in the hydraulic system, requiring further analysis based on the operating conditions of the walking beam and other components to accurately determine the cause.

[0089] Specifically, the step of determining whether to issue an oil leak alarm based on the working status can be achieved by:

[0090] If the working status of the equipment in the outlet section system indicates that the equipment in the outlet section system is in an operating state, it is determined that there is no need to issue an oil leakage alarm message; if the working status of the equipment in the outlet section system indicates that the equipment in the outlet section system is in a non-operating state, it is determined that an oil leakage alarm message needs to be issued.

[0091] When the walking beam at the mill outlet is in motion, the oil level in the tank will fluctuate greatly. Therefore, although the difference at this time is greater than the set difference, it may be caused by the movement of the walking beam, not by oil leakage in the tank. Therefore, there is no need to issue an oil leakage alarm.

[0092] If the walking beam is in a non-operating state at this time, it indicates that there is a high probability of oil leakage and an oil leakage alarm needs to be issued.

[0093] In this embodiment, the comparison result between the actual oil level detected and the oil level set value, as well as the operating status of equipment such as the walking beam, are combined to determine whether there is an oil leakage phenomenon, thereby preventing equipment such as the walking beam at the mill outlet that consumes a lot of oil from interfering with the alarm of the dynamic detection program of the oil level in the mill tank. This is more consistent with the actual process scenario and the judgment result is more accurate.

[0094] In addition, in this embodiment, the set difference value can be set smaller, that is, the threshold value used for comparison is set smaller, so that when the rolling mill oil pipe is broken or the sealing ring is damaged, the oil leakage accident can be quickly discovered.

[0095] In the hydraulic system of a pickling mill, the hydraulic station's main pump supplies oil to the on-site hydraulic equipment, while the hydraulic station's circulating pump circulates and cools the oil. Hydraulic stations typically have backup main pumps and backup circulating pumps. However, when a problem occurs with the main pump or circulating pump, operators often switch to the backup pump only to discover that the backup pump is faulty and unable to operate. Therefore, in practice, management requirements are typically established, requiring operators to regularly switch to the backup pump, promptly identify any problems with the backup pump, and complete switching records. However, this practice is ineffective. Operators often forget to regularly switch to the backup pump and falsify switching records, resulting in unreliable operation of the backup main pump or circulating pump.

[0096] Furthermore, strip thickness control in the pickling mill is achieved by automatic roll gap control hydraulic cylinders on the drive and operating sides of each mill. The mill control system controls the operation of the hydraulic cylinders via servo valves. Each hydraulic cylinder is equipped with two servo valves. Under normal circumstances, one servo valve is in online operation and the other is in standby mode. However, when the online servo valve experiences a problem, the standby servo valve fails and the system is switched to the standby servo valve.

[0097] Based on the above analysis and to address the aforementioned issues, in this embodiment, each of the multiple devices included in the rolling mill control system has a standby state and an active state, and the two states can be switched between. When a device is in the active state, it is referred to as an active device; when it is in the standby state, it is referred to as a standby device. When an active device stops being used, it becomes a standby device. When a standby device begins operating, it becomes an active device.

[0098] On this basis, the provided method for controlling cold rolling stability may further include the following steps:

[0099] When it is detected that a device in use stops running, the device's status is switched to the standby status and the device's downtime is recorded; the cumulative downtime is counted starting from the downtime, and when it is detected that the cumulative downtime reaches the set duration, a switching prompt message is issued; when a switching operation is detected, the device in the standby status is controlled to be put into operation and its status is switched to the in-use status, and when it is detected that the working time of the device reaches the preset duration, the cumulative downtime is cleared.

[0100] The plurality of devices may include a main pump, a main circulation pump, a main servo valve, etc., and the status of the plurality of devices may be switched between a standby state and an active state. In this embodiment, an automatic detection program for the status of active devices and standby devices in the system is added.

[0101] When the main pump or circulating pump equipment in the hydraulic station stops, it becomes the standby pump. When the control system detects that the pump operation feedback is stopped, the control system automatically stores the standby pump downtime. The control system then uses the current actual time to subtract the stored pump downtime, which is the cumulative downtime of the standby pump. The accumulated downtime can be displayed on the on-site screen or remote monitoring system. When the accumulated downtime exceeds the set duration, an alarm will automatically sound to prompt the operator or manager that the cycle for switching the standby pump into use has arrived. After the operator or manager triggers the switching operation, the standby pump starts to work online and becomes the active pump. When the standby pump working time reaches the preset time (for example, set to 1 hour), the accumulated downtime is reset.

[0102] Similarly, when the active servo valve in a hydraulic control system is deactivated, becoming the standby servo valve, and the control system servo valve's operational feedback reaches zero, the servo valve's control system automatically stores the servo valve's downtime. The control system then subtracts the stored servo valve downtime from the current actual time, representing the servo valve's cumulative downtime. This accumulated downtime is displayed on the on-site screen or remote monitoring system. When the accumulated downtime exceeds the set duration, the servo valve automatically issues an alarm, alerting the operator or management personnel that it's time to switch to the standby servo valve. When the standby servo valve begins online operation, becoming the active servo valve, the accumulated downtime is reset to zero once the standby servo valve's operating time reaches a preset duration (e.g., one hour).

[0103] If, after the control system issues a command to operate the standby pump, no pump operation feedback is received within a set period of time (e.g., 5 seconds), the control system determines that the pump is faulty, stores the pump fault, and displays it on the screen. Furthermore, a prompt message may be issued to inform the operator or manager that the pump is faulty. The stored fault status is not reset until the operator resets the pump.

[0104] After the control system sends 4-20 mA DC to control the servo valve, if the control system receives zero operational feedback from the servo valve after a set period of time (e.g., 5 seconds), the control system determines that the servo valve is faulty, stores the fault information, and displays it on the screen. Furthermore, a prompt message is issued to inform the operator or manager that the servo valve is in a faulty state. The stored fault status is not reset until the operator resets the servo valve.

[0105] When the mill rolls wear or are replaced, their diameters change, causing fluctuations in the rolling line. This is accomplished by adjusting the strip's path through the mill using the wedge adjustment device located below the stand to maintain a constant rolling height. Failure of the wedge displacement sensor is initially manifested by unstable output signals containing interference pulses, which cause vibrations in the entire rolling line's closed-loop control system. Fluctuations in the rolling line can also cause drastic changes in the mill roll gap, directly leading to strip breakage.

[0106] Based on the above considerations, the cold rolling stability control implementation method provided in this embodiment may further include the following steps:

[0107] When the rolling mill switches from roll changing mode to rolling mode, the actual position of the wedge adjustment device is obtained during the switching; when the rolling mill is in rolling mode, the position information of the wedge adjustment device is set to the actual position.

[0108] Because the cam adjustment mechanism doesn't adjust in rolling mode, the mill's cam program has been modified so that, while the mill is rolling and the cam adjustment mechanism is locked, the current cam adjustment mechanism position is set to the actual position saved when switching from roll change mode to rolling mode. This ensures that even if the cam displacement sensor experiences an interference pulse, the cam adjustment mechanism remains stable, ensuring continued stable mill operation.

[0109] The hydraulic control equipment of a rolling mill, such as the exit unloading trolley and the walking beam, is controlled by proportional valves controlled by 4-20 mA DC. The control system's output card outputs 4-20 mA DC to control the corresponding proportional valves, thereby controlling the operation of the corresponding equipment. Failures with the output card, proportional valve, cylinder, or cable can cause the corresponding equipment to malfunction. In such cases, a multimeter is required to locate the corresponding drawings and wiring terminals, perform measurements, and determine the fault point, which can be time-consuming to troubleshoot.

[0110] Based on the above considerations, in this embodiment, a digital display meter can be set up between the rolling mill control system and the exit section system. During the execution process, the output signal of the rolling mill control system is first transmitted to the digital display meter and then to the proportional valve of the equipment in the exit section system. The output signal is displayed on the digital display meter, and the proportional valve of the equipment in the exit section system is controlled by the output signal. In turn, the unloading trolley, walking beam, etc. are controlled.

[0111] In this way, when the proportional valve control equipment such as the rolling mill exit unloading trolley and walking beam operates abnormally, maintenance personnel can easily see whether the output 4~20mADC of the control system is normal, so that they can clearly judge the fault and greatly reduce the fault handling time.

[0112] A pickling mill typically uses multiple stands for continuous rolling, for example, five stands. The finished strip thickness is determined by the automatic roll gap control system of the five rolling mills. Each rolling mill's automatic roll gap control system uses a roll gap position closed loop, which is determined by the performance of each mill's servo valve, unloading valve, roll gap displacement sensor, and roll gap control hydraulic cylinder. When problems arise with the servo valve, unloading valve, roll gap displacement sensor, or roll gap control hydraulic cylinder, they cannot be effectively detected, affecting the stability of the roll gap position closed loop of each rolling mill. Unstable roll gap position closed loop stability control of one rolling mill can lead to unstable rolling of the five rolling mills in the pickling mill, causing strip breakage or crushing within the mills.

[0113] Based on the above research findings, the control method of the pickling mill provided in this embodiment further includes the following steps:

[0114] The roll gap control servo valve is controlled by a positive or negative small current signal output method, so that the roll gap hydraulic cylinder moves slowly upward or downward respectively; the sensor value of the roll gap hydraulic cylinder after each upward movement to the mechanical upper limit position or the sensor value after each downward movement to the mechanical lower limit position is obtained by the roll gap displacement sensor.

[0115] Compare the sensor values after each roll gap hydraulic cylinder moves upward to the mechanical upper limit position, or each time it moves downward to the mechanical lower limit position in a single rolling mill or multiple rolling mills to detect whether the roll gap displacement sensor is abnormal, whether there is interference signal influence, and whether there is an abnormal roll gap control servo valve or roll gap hydraulic cylinder.

[0116] In this embodiment, a roll gap position measurement stability test is provided for the mill's hydraulic closed-loop roll gap control system. The stroke of the roll gap control hydraulic cylinder can be 165 mm. During the test process, the mill's roll gap is first controlled to open, a pump in the mill's servo hydraulic system is activated, and the hydraulic pressure reducing valve is adjusted to reduce the servo hydraulic system pressure, for example, from 26 MPa to 10 MPa.

[0117] Remove the working rolls, intermediate rolls, and backup rolls of the rolling mill to be tested. Run the configured roll gap position measurement stability detection program to directly control the output of the roll gap control servo valve using a positive or negative low current output signal control method.

[0118] When using a continuous positive current output signal, the signal amplitude is 5%. When using a negative positive current output signal, the signal amplitude is -5%.

[0119] When the roll gap control servo valve is given a positive current, the roll gap hydraulic cylinders on the transmission side and the operating side of the rolling mill move upward to the mechanical upper limit position.

[0120] When the roll gap control servo valve is given a negative current, the roll gap hydraulic cylinders on the transmission side and the operating side of the rolling mill move downward to the mechanical lower limit position.

[0121] Theoretically, the sensor values detected by the roll gap displacement sensor each time the roll gap hydraulic cylinder moves to the upper limit position of the machine should be the same. If they are inconsistent, there may be an abnormality in the roll gap displacement sensor. You can check the installation and cleanliness of the roll gap displacement sensor, or replace the roll gap displacement sensor.

[0122] Similarly, the sensor value obtained by the roll gap displacement sensor each time the roll gap hydraulic cylinder moves to the mechanical lower limit should theoretically be the same. If it is inconsistent, it may be that the roll gap displacement sensor has an abnormality.

[0123] In this embodiment, the full-line coordinated controller of the rolling mill control system, using a roll gap position measurement stability detection program, simultaneously controls the output of the drive-side and operator-side roll gap control servo valves of five rolling mills to 5%. The roll gap hydraulic cylinders on the drive and operator sides of the five rolling mills are slowly moved forward to their upper mechanical limit positions. The roll gap displacement sensor curve data for the five rolling mills is analyzed as the roll gaps on the drive and operator sides slowly open. The roll gap curves for the five rolling mills should be synchronized over the time period from 0 to 165 mm. If the roll gap opening curves for any stand are out of sync, this indicates a possible performance anomaly in the roll gap control servo valve or roll gap hydraulic cylinder of that stand, requiring replacement.

[0124] In addition, in this embodiment, anomaly detection can also be performed in the following ways:

[0125] Simultaneously, the roll gap hydraulic cylinders of multiple rolling mills are controlled to move forward rapidly, and the curve information of the roll gap is detected by the roll gap displacement sensor; the curve information of the roll gaps of all rolling mills is compared to detect whether there is any abnormality in the roll gap hydraulic cylinders of each rolling mill.

[0126] The servo hydraulic system of the rolling mill can start and run four pumps, and the pressure of the servo hydraulic system is 26MPa. The backup rolls, intermediate rolls and work rolls are installed in the rolling mill.

[0127] Five rolling mills are started in hot roller state, and the rolling force of the five rolling mills is under closed-loop control. The rolling force of each stand is 2MPa, and the rolling mill speed is 200m / min.

[0128] The full-line coordination controller of the rolling mill control system simultaneously sends a command for the rolling mill roll gap to be quickly opened to the five rolling mill controllers. The five rolling mill roll gaps are quickly opened at the same time, and the roll gap hydraulic cylinders are opened to the maximum mechanical position at the same time.

[0129] Analyze the curve data of the roll gap displacement sensor when the roll gap of the five rolling mills is quickly opened. During the time period when the roll gap of the five rolling mills opens from 0 to 20 mm, the roll gap curves should be synchronized. If the roll gap opening curve of a certain frame is not synchronized, it means that there is a problem with the performance of the quick-opening valve or hydraulic cylinder of the frame and it needs to be replaced.

[0130] In summary, the cold rolling stability control implementation method provided in this embodiment adopts different limiting mechanisms to limit the stringing rolls, support roll balancing, working roll balance bending rolls, intermediate roll balance bending roll systems and wedge hydraulic servo control systems to prevent system vibration caused by sensor interference pulses.

[0131] Equipped with an automatic detection program for the status of standby equipment in the rolling mill hydraulic control system, it can conveniently and effectively digitally detect and display the status of standby equipment such as the main pump, circulation pump, and servo valve of the hydraulic control system, ensuring that the status of the standby equipment is controllable and eliminating the uncertainty caused by manual management.

[0132] In addition, a dynamic detection program for the oil level in the hydraulic station tank has been designed to diagnose oil leakage in the rolling mill in a timely and effective manner, and to eliminate detection interference caused by the movement of equipment such as the walking beam in the exit section system. This reduces the losses and accidents caused by oil leakage and reduces the probability of misjudgment.

[0133] Furthermore, a real-time detection program for the proportional valve output of the rolling mill control system was designed to analyze and diagnose equipment failures controlled by the proportional valve in a timely and effective manner. This can solve the problem of long fault handling time when on-site maintenance personnel maintain proportional valve control equipment, thereby achieving the purpose of reducing equipment failures and fault handling time.

[0134] By adopting different limiting mechanisms to limit the roll stringing, support roll balancing, work roll balance bending, intermediate roll balance bending system and wedge hydraulic servo control system, the system vibration caused by sensor interference pulse is prevented.

[0135] By designing the stability of the rolling mill roll gap hydraulic closed-loop control system and the synchronization inspection and detection method of multiple rolling mill roll gap controls, the performance of the servo valve, unloading valve, roll gap displacement sensor, and roll gap control hydraulic cylinder can be effectively detected to ensure the stability of the rolling mill roll gap hydraulic control system.

[0136] In order to execute the corresponding steps in the above-mentioned cold rolling stability control implementation method embodiment and various possible methods, a method for implementing the cold rolling stability control implementation device is given below. Figure 4 , Figure 4 This is a functional module diagram of a cold rolling stability control device provided by an embodiment of the present invention. It should be noted that the basic principles and technical effects of the cold rolling stability control device provided by this embodiment are the same as those of the corresponding method embodiments described above. For the sake of simplicity, any parts not mentioned in this embodiment can be referred to the corresponding contents of the corresponding method embodiments described above. The cold rolling stability control device includes:

[0137] a determination module, configured to obtain position or pressure information detected by the rolling mill sensor during operation of the rolling mill, and determine a preliminary output signal of the rolling mill control servo valve based on the position or pressure information;

[0138] Detection module, used to detect the working mode of the rolling mill;

[0139] a first processing module, configured to select a first preset amplitude limit value when the rolling mill is in a rolling mode, and perform amplitude limit processing on a preliminary output signal of a rolling mill control servo valve based on the first preset amplitude limit value;

[0140] a second processing module, configured to select a second preset amplitude limit value when the rolling mill is in a roll changing mode, and perform amplitude limiting processing on a preliminary output signal of the rolling mill control servo valve based on the second preset amplitude limit value;

[0141] A control module is used to control the rolling mill control hydraulic cylinder based on the final output signal of the rolling mill control servo valve after the limiting process.

[0142] The above are merely embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for controlling cold rolling stability, characterized in that: For controlling a pickling mill group, the pickling mill group includes a mill system and a mill control system, the mill system includes a mill, the mill control system includes a mill control hydraulic cylinder, a mill sensor and a mill control servo valve, the method comprising: obtaining position or pressure information detected by the rolling mill sensor during operation of the rolling mill, and determining a preliminary output signal of the rolling mill control servo valve based on the position or pressure information; detecting an operating mode of the rolling mill, selecting a first preset amplitude limit value when the rolling mill is in a rolling mode, and performing amplitude limiting processing on a preliminary output signal of a control servo valve of the rolling mill based on the first preset amplitude limit value; When the rolling mill is in a roll changing mode, selecting a second preset amplitude limit value, and performing amplitude limiting processing on a preliminary output signal of the rolling mill control servo valve based on the second preset amplitude limit value; The rolling mill control hydraulic cylinder is controlled based on the final output signal of the rolling mill control servo valve after the limiting process.

2. The method for controlling cold rolling stability according to claim 1, characterized in that: The step of controlling the rolling mill control hydraulic cylinder includes: When the rolling mill is in a rolling mode and has not passed through a strip weld, controlling the rolling mill control hydraulic cylinder in a PID adjustment mode with a first set gain coefficient and a first set integral time; When the rolling mill is in rolling mode and passes through a strip weld, the rolling mill control hydraulic cylinder is controlled in a PID adjustment mode with a second set gain coefficient and a second set integral time; The second set gain coefficient is smaller than the first set gain coefficient, and the second set integration time is larger than the first set integration time.

3. The method for controlling cold rolling stability according to claim 1, characterized in that: The pickling mill group further includes an outlet section system, and the rolling mill control system further includes a hydraulic station oil tank, wherein an oil level detection sensor is provided in the hydraulic station oil tank; The method further comprises: Obtaining the actual oil level in the oil tank of the hydraulic station detected by the oil level detection sensor, and obtaining the working status of the equipment in the outlet section system; Whether to issue an oil leakage alarm signal is determined based on the actual oil level and the working status of the equipment in the outlet section system.

4. The method for controlling cold rolling stability according to claim 3, characterized in that: The step of determining whether to issue an oil leakage alarm signal based on the actual oil level and the working status of the equipment in the outlet section system includes: Calculating a difference between the actual oil level and a set oil level value, and comparing the difference with a set difference value; When the difference is less than or equal to the set difference, it is determined that there is no need to issue an oil leakage alarm message; When the difference is greater than the set difference, the working status of the equipment in the outlet section system is obtained, and whether to issue an oil leakage alarm is determined based on the working status.

5. The method for controlling cold rolling stability according to claim 4, characterized in that: The step of determining whether to issue an oil leakage alarm based on the working status includes: If the working state of the equipment in the outlet section system indicates that the equipment in the outlet section system is in an operating state, it is determined that there is no need to issue an oil leakage alarm; If the working state of the equipment in the outlet section system indicates that the equipment in the outlet section system is in a non-operating state, it is determined that an oil leakage alarm message needs to be issued.

6. The method for controlling cold rolling stability according to claim 1, characterized in that: The rolling mill control system includes a plurality of devices, each of the devices having a standby state and an active state, and the method further includes: When it is detected that a device in use stops operating, the device is switched to a standby state and the downtime of the device is recorded; Starting from the downtime, the accumulated downtime is counted, and when the accumulated downtime reaches the set duration, a switching prompt message is issued; When a switching operation is detected, the device in standby state is controlled to be put into operation and its state is switched to the in-use state. When it is monitored that the working time of the device reaches a preset time, the accumulated inactivity time is cleared.

7. The method for controlling cold rolling stability according to claim 1, characterized in that: The pickling mill group further includes an outlet section system, and a digital display meter arranged between the rolling mill control system and the outlet section system; The method further comprises: The output signal of the rolling mill control system is first transmitted to the digital display meter and then transmitted to the proportional valve of the equipment in the outlet section system, so that the output signal is displayed through the digital display meter, and the proportional valve of the equipment in the outlet section system is controlled by the output signal.

8. The method for controlling cold rolling stability according to claim 1, characterized in that: The rolling mill control system further includes a wedge adjustment device located below the rolling mill, and the method further includes: When the rolling mill switches from a roll changing mode to a rolling mode, obtaining an actual position of the wedge adjustment device at the time of switching; When the rolling mill is in the rolling mode, the position information of the wedge adjustment device is set to the actual position.

9. The method for controlling cold rolling stability according to claim 1, characterized in that: The rolling mill system includes a plurality of rolling mills, the rolling mill control system further includes a roll gap control servo valve, a roll gap hydraulic cylinder, and a roll gap displacement sensor, and the method further includes: The number of interference pulses occurring in the roll gap displacement sensor in a single rolling mill is accumulated to detect whether the roll gap displacement sensor is abnormal.

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