Recognition and early warning method for abnormal blocking of rolling mill plate blank

Abstract

The invention belongs to the technical field of automatic control of hot continuous rolling, and particularly relates to a method for identifying and early warning abnormal blocking of a plate blank of a rolling mill, which comprises the following steps of: additionally arranging pressure relays in guide hydraulic oil cylinder loops at an inlet and an outlet of a roughing mill; and the system judges whether the threshold value is exceeded according to the hydraulic pressure change and alarms for shutdown. Meanwhile, a theoretical rolling time model is established in combination with the position of a roughing mill thermal detection device and the rolling speed, actual rolling time is collected in real time, difference judgment is conducted, when the time difference exceeds a set threshold value, it is judged that blocking is generated, and shutdown operation is triggered as well; the method has the advantages of being rapid in judgment, accurate in control, simple in structure, high in adaptability and the like, steel piling accidents of the roughing mill can be effectively prevented, and the safety and stability of a hot rolling production line are improved.

Description

Technical Field

[0001] This invention belongs to the field of automated control technology for iron and steel metallurgical rolling, and relates to a system for equipment safety monitoring and intelligent shutdown of the roughing mill section in a hot continuous rolling production line. Specifically, it is a method for identifying and warning of abnormal obstruction of rolling mill slabs. Background Technology

[0002] Hot rolling mill is one of the key processes in modern steel manufacturing. As the first step in the hot rolling process, the roughing mill is mainly responsible for the initial compression and extension of the heated slab. Its operational stability is directly related to the efficiency and product quality of the entire production line.

[0003] During roughing, various factors such as slab tilting or buckling, improper installation of guides and scrapers, or inconsistent heights can easily lead to rolling abnormalities. When the slab makes abnormal contact with the internal mechanical structure of the roughing mill, rolling may be obstructed, and in severe cases, slabs may accumulate, a phenomenon known as "slab accumulation accident." Such accidents not only interrupt the rolling rhythm but also severely damage critical equipment such as inlet or outlet guides, roll systems, and hydraulic devices, resulting in equipment downtime, increased repair costs, and lost production capacity.

[0004] Traditional steel stacking accident identification relies on operator experience or equipment overload alarms, but these methods suffer from slow response times and high false alarm rates. Especially under high-speed, high-temperature, and highly automated operating conditions, manual intervention alone is insufficient to prevent accidents in a timely and effective manner. Therefore, there is an urgent need for an intelligent early warning and control method based on the linkage between rolling process parameters and real-time data, capable of promptly identifying abnormal states in the early stages of steel stacking and proactively issuing shutdown commands to prevent further escalation of the accident.

[0005] Although existing technologies include research on rolling load detection and hot rolling signal acquisition, there is still no mature method to compare theoretical rolling time with actual time to determine the obstruction state. Therefore, developing an early warning and control system that combines equipment pressure changes, rolling speed, equipment structural parameters, load triggering conditions, and time discrimination mechanisms will provide important protection for safe hot rolling production. Summary of the Invention

[0006] The purpose of this invention is to provide a method for identifying and warning of abnormal obstruction of slabs in rolling mills. This method can overcome the shortcomings of existing technologies, such as excessive human intervention, delayed response, and insufficient warning accuracy. It can effectively avoid steel pile-up accidents, protect equipment safety, and improve the stability and reliability of hot rolling production line operation.

[0007] The technical solution adopted by the present invention to achieve the above objectives is as follows: A method for identifying and providing early warning of abnormal obstruction in rolling mill slabs includes the following: S1. Abnormal contact identification of slab based on hydraulic signal of guide cylinder; S11. Install pressure relays in the hydraulic circuits of the guide cylinder hydraulic systems at the inlet and outlet of the roughing mill. S12, Configure a threshold pressure value for the pressure relay; S13. Real-time monitoring of the pressure borne by the guide. If the hydraulic pressure exceeds the set threshold pressure value, an alarm will be triggered immediately to remind manual inspection and issue a shutdown command. S2. Slab resistance identification based on the theoretical and actual rolling time difference; S21. Heat detection sensors are installed at the inlet and outlet of the roughing mill; S22. Calculate the theoretical rolling time of the slab through the roughing mill by combining the rolling speed and the load relay signal of the rolling pass; S23. Record the actual rolling time using a logic scan method; S24. By establishing a time domain model through thermal sensors, rolling speed parameters, and logic scanning, the obstruction of the slab is detected. When the difference between the actual rolling time and the theoretical rolling time exceeds the set threshold time value, the slab is automatically judged to be obstructed, an early warning is issued, and a stop command is immediately issued.

[0008] Furthermore, the time-domain model established using thermal sensors, rolling speed parameters, and logic scanning methods includes: Record the fixed distance between the thermal sensors at the inlet and outlet of the roughing mill. The theoretical rolling time is calculated based on the fixed distance between the thermal sensors and the rolling speed set for the current pass. In the automatic operation mode of the system, after detecting that the load relay of the roughing mill is ON, the time scanning program is started to record the actual rolling time. Compare the difference between the theoretical rolling time and the actual rolling time; If the difference is greater than the set threshold time, it is determined that the slab is obstructed during the rough rolling process. The control system immediately issued a stop command and activated the alarm.

[0009] Furthermore, the time scanning procedure is as follows: (1) Check every 0.05 seconds whether the following two conditions are met simultaneously: a. A rolling pass signal was detected in the roughing mill; b. No slab was detected during export heat inspection; (2) If both conditions are met, the scan time is accumulated; if neither condition is met, the stop time is accumulated.

[0010] Furthermore, the slab abnormal contact identification mechanism based on the guide cylinder hydraulic signal and the slab obstruction identification mechanism based on the theoretical and actual rolling time difference can be simultaneously connected to the roughing mill control system. When either mechanism triggers an abnormal condition, the system will issue a shutdown and alarm command.

[0011] Furthermore, the threshold pressure, rolling speed, and threshold time are adaptively set according to the slab specifications and production rhythm.

[0012] The beneficial effects of this invention are: This invention achieves rapid identification and automatic response control of abnormal slab behavior through a complementary mechanism that combines pressure changes in the guide hydraulic circuit with the rolling time difference. It can accurately identify abnormal states such as slab tilting, buckling, or stagnation as soon as they appear, significantly improving the timeliness of early warning of steel accumulation risks. This enables early, efficient, and accurate identification and handling of abnormal conditions in the roughing mill, greatly reducing the risk of steel accumulation accidents. When it is determined that the slab is in abnormal contact with the guide or internal components, or fails to complete the normal rolling process within the set time, the system immediately stops the rolling action to prevent further slab accumulation or jamming. This effectively protects the guide, scraper, and roll system of the roughing mill, effectively protecting production equipment, reducing equipment failure rates and maintenance costs, and ensuring continuous, safe, and stable production.

[0013] This invention eliminates the reliance on human experience or visual judgment, and automatically determines whether slab obstruction occurs by relying on changes in system parameters and logical analysis, thereby automatically executing shutdown and alarm operations, improving the intelligence and inherent safety level of the rolling process.

[0014] This invention only requires adding a pressure relay to the existing rolling mill hydraulic system and logically extending the existing heat detection device and control system software. It requires no large-scale equipment modification and possesses good engineering feasibility and adaptability for widespread application. It can be parameterized to adapt to different production scenarios; whether it's pressure threshold, rolling speed, or time difference threshold, all can be flexibly set in the control system to adapt to different slab specifications, production rhythms, and rolling conditions, exhibiting wide applicability and stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the control hardware structure of the method of the present invention; In the diagram: 1. Human-Machine Interface; 2. Control System PLC; 3. First Pressure Relay; 4. Second Pressure Relay; 5. Inlet Guide; 6. Outlet Guide; 7. First Thermal Sensor; 8. Second Thermal Sensor; 9. Roughing Mill. Detailed Implementation

[0016] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred examples described herein are for illustration and explanation only and are not intended to limit the present invention.

[0017] like Figure 1 As shown, a first pressure relay 3 and a second pressure relay 4 are added to the hydraulic drive system circuits of the inlet guide 5 and outlet guide 6 of the roughing mill 9, respectively, to collect the pressure signals of the guide actuators in real time. The signals of the first pressure relay 3 and the second pressure relay 4 are connected to the roughing mill control system PLC2, and a threshold pressure value is set, usually according to the actual working conditions (e.g., 8~12 MPa). When the slab enters the roughing mill, if there are abnormalities such as tilting or buckling, the contact resistance with the guide will increase, and the back pressure of the hydraulic cylinder will rise rapidly. Once the signal pressure value is detected to be greater than the threshold pressure value, the system immediately triggers an alarm and sends a command to the control system to stop the roughing mill. At the same time, a fault prompt is displayed on the human-machine interface 1 (HMI), requiring the operator to conduct on-site troubleshooting. By setting an alarm delay (e.g., 0.2 seconds), false shutdowns due to short-term interference are avoided, thus improving system stability.

[0018] A first thermal detection sensor 7 and a second thermal detection sensor 8 are installed at the inlet and outlet of the roughing mill 9, respectively, to detect the slab head passing signal. The thermal detection signal is connected to the roughing mill control system PLC2. The human-machine interface 1 sends the rolling speed V and the roughing mill pass signal of each pass to the control system PLC2 via communication. The system stores the fixed distance L between the inlet and outlet thermal detectors and the roughing mill; and calculates the theoretical rolling time Ttheory.

[0019] In actual production, when the system is in automatic control mode and the roughing mill load relay is ON, a time scanning program is started to statistically analyze the actual rolling time. Every 0.05 seconds, it checks whether the following two conditions are met: the roughing mill pass signal is detected as "valid"; and the exit hot inspection still "does not detect" the slab head. If the above conditions are met continuously, the current time is accumulated as the actual rolling time (Tactual). If either condition is no longer met, the stop time is accumulated, and the difference is calculated. If the difference is greater than the threshold time (0.3 seconds), the system judges that the slab is running abnormally and issues a shutdown control signal.

[0020] The two identification and judgment methods mentioned above are respectively connected to the control system PLC of the hot rolling roughing mill, and the shutdown is triggered by "OR" logic: when either mechanism triggers an abnormal condition, that is, the pressure relay detects that the pressure exceeds the threshold or the time difference exceeds the threshold, the control system immediately controls the mill to stop to ensure that the equipment is not further damaged; all parameters (pressure threshold, rolling speed, time threshold, scanning frequency) can be set through the HMI interface to adapt to different steel grades, working conditions and production plans.

[0021] The method of this invention integrates each monitoring module with the rolling mill control system, supporting closed-loop control of the entire process, including real-time signal acquisition, anomaly judgment, alarm output, shutdown control, and human-machine interface prompts. The scanning logic relies on the combined condition control of "pass signal detected" and "no signal detected at the exit hot inspection", which has logical judgment capability rather than single-point triggering, and can effectively reduce the false judgment rate.

[0022] Hydraulic pressure fluctuations are used as an anomaly detection signal source to achieve early anomaly identification. By adding a pressure relay to the hydraulic circuit of the guide cylinder in the roughing mill, it monitors in real time whether the slab is in abnormal contact with the guide due to tilting or buckling. When the pressure value exceeds the set threshold, an alarm signal is automatically triggered, the system interrupts rolling, and prompts manual inspection. At the same time, a "comparison mechanism between theoretical rolling time and actual rolling time" is introduced. A model is established using multiple parameters such as hot inspection position, rolling speed, and load ON signal to determine if the slab is obstructed. A triple-condition start logic of "automatic mode + load relay ON + slab timing" is adopted to improve fault tolerance. When "theoretical time - actual time ≥ threshold value", obstruction can be determined, and the system can automatically issue a stop rolling command, providing early protection. The time comparison method enables rapid identification of the initial signs of steel piling, avoiding equipment damage caused by slab tilting, unevenness of the scraper guide, etc. The threshold time setting has a certain degree of adaptability and can be flexibly adjusted according to the production rhythm and different slab specifications.

[0023] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for identifying and warning of abnormal obstruction in rolling mill slabs, characterized in that: Includes the following: S1. Abnormal contact identification of slab based on hydraulic signal of guide cylinder; S11. Install pressure relays in the hydraulic circuits of the guide cylinder hydraulic systems at the inlet and outlet of the roughing mill. S12, Configure a threshold pressure value for the pressure relay; S13. Real-time monitoring of the pressure borne by the guide. If the hydraulic pressure exceeds the set threshold pressure value, an alarm will be triggered immediately to remind manual inspection and issue a shutdown command. S2. Slab resistance identification based on the theoretical and actual rolling time difference; S21. Heat detection sensors are installed at the inlet and outlet of the roughing mill; S22. Calculate the theoretical rolling time of the slab through the roughing mill by combining the rolling speed and the load relay signal of the rolling pass; S23. Record the actual rolling time using a logic scan method; S24. By establishing a time domain model through thermal sensors, rolling speed parameters, and logic scanning, the obstruction of the slab is detected. When the difference between the actual rolling time and the theoretical rolling time exceeds the set threshold time value, the slab is automatically judged to be obstructed, an early warning is issued, and a stop command is immediately issued.

2. The method for identifying and warning of abnormal obstruction of slab in a rolling mill according to claim 1, characterized in that: The time-domain model established using thermal sensors, rolling speed parameters, and logic scanning includes: (1) Record the fixed distance between the thermal detection sensors at the inlet and outlet of the roughing mill. (2) Calculate the theoretical rolling time based on the fixed distance between the thermal sensors and the rolling speed set for the current pass; (3) In the automatic operation mode of the system, after the ON state of the load relay of the roughing mill is detected, the time scanning program is started to record the actual rolling time; (4) Compare the difference between the theoretical rolling time and the actual rolling time; (5) If the difference is greater than the set threshold time, it is determined that the slab is obstructed during the rough rolling process; (6) The control system immediately issues a stop command and activates the alarm.

3. The method for identifying and warning of abnormal obstruction of slab in a rolling mill according to claim 2, characterized in that: The time scanning procedure is as follows: (1) Check every 0.05 seconds whether the following two conditions are met simultaneously: a. A rolling pass signal was detected in the roughing mill; b. No slab was detected during export heat inspection; (2) If both conditions are met, then the scan time is accumulated; If any condition is not met, the stopping time is incremented.

4. The method for identifying and warning of abnormal obstruction of slab in a rolling mill according to claim 1, characterized in that: The slab abnormal contact identification mechanism based on the guide cylinder hydraulic signal and the slab obstruction identification mechanism based on the theoretical and actual rolling time difference can be simultaneously connected to the roughing mill control system. When either mechanism triggers an abnormal condition, the system will issue a shutdown and alarm command.

5. The method for identifying and warning of abnormal obstruction of slab in a rolling mill according to claim 1, characterized in that: The threshold pressure value, rolling speed, and threshold time are adaptively set according to the slab specifications and production rhythm.

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