Method for controlling uniform head and tail temperature in high-strength steel plate rolling process

Abstract

The invention discloses a control method for uniform head and tail temperature in a high-strength steel plate rolling process, which is realized based on a rolling mill guide cooling water pipe device consisting of a guide base frame, a cooling water pipe, an electric control valve, a position sensor and a PLC (Programmable Logic Controller) control system, the cooling water pipe is integrated on the guide base frame, the electric control valve is connected with the cooling water pipe, and the position sensor is connected with the PLC control system. The position sensor is in signal connection with the PLC control system, the PLC control system is electrically connected with the electric adjusting valve, and the specific control method comprises the following steps that (1) the device is installed and debugged; 2) setting basic parameters; 3) position and speed detection; 4) dynamic avoidance and time node calculation; 5) gradient cooling control; and 6) closed-loop feedback regulation and control. The cooling water pipe assembly is integrated in the rolling mill rear guide and guard system, linkage control of the electric adjusting valve and the position detection mechanism is combined, accurate space-time control over cooling water flow is achieved, a closed-loop temperature control system is formed, the problem that the temperature of the head and the tail of steel plate rolling is not uniform is effectively solved, and the steel plate product quality and the production yield are improved.

Description

Technical Field

[0001] This invention belongs to the field of metal processing technology, specifically relating to a method for controlling the uniform temperature at the beginning and end of the rolling process of high-strength steel plates. It is applicable to rolling production lines for high-strength steel products such as medium and heavy plates and wire rods, and is especially suitable for high-strength steel production scenarios with stringent requirements for temperature uniformity, such as military and energy equipment. Background Technology

[0002] In the high-strength steel plate rolling process, uneven temperature distribution at the beginning and end of the rolling process has long been a technical challenge in the industry, directly affecting the quality of steel plate products and production efficiency. Current traditional laminar flow cooling systems have several drawbacks: the long cooling zone leads to a final cooling temperature control error of ±15℃; the distance between temperature sensors and control equipment exceeds 10 meters, resulting in poor data transmission timeliness and significant delays in temperature control response; and cooling water splashing can interfere with temperature sensor readings, causing measurement errors.

[0003] The temperature difference between the head and tail of a rolled product is affected by multiple factors. During the rolling process of a 20mm thick steel plate, the temperature difference between the head, middle, and tail can reach 50℃. The temperature difference between the head and tail of a 220mm steel billet produced by a continuous casting machine can reach 40-50℃, directly causing the standard deviation of the yield strength of the rolled steel plate to exceed the standard. Existing improvement measures in the industry all have significant shortcomings: although induction heating technology can equalize the temperature of the billet, the power consumption per ton of steel is as high as 15-30 kWh; edge shielding devices can only improve the temperature difference in the width direction and cannot solve the problem of the head and tail temperature difference in the length direction; traditional water cooling systems have a steel removal rate as high as 1% due to the problems of "thermal length" and "transition length", resulting in serious waste of metal resources. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method for controlling the uniform temperature at the beginning and end of the high-strength steel plate rolling process. By integrating a cooling water pipe assembly into the mill's rear guide system and combining it with the linkage control of an electric regulating valve and a position detection mechanism, precise spatiotemporal control of the cooling water flow is achieved, forming a closed-loop temperature control system. This effectively solves the problem of uneven temperature at the beginning and end of the steel plate rolling process, thereby improving the quality of steel plate products and the yield rate.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process. This method is based on a rolling mill guide cooling water pipe device, which consists of a guide frame, cooling water pipes, an electric regulating valve, a position sensor, and a PLC control system. This device is integrated into the rolling mill's rear guide system, forming a closed-loop temperature control system. The specific control method includes the following steps: 1) Installation and commissioning of the device: Fix the guide frame on the exit side of the rolling mill. The deviation between the center line of the cooling water pipe and the rolling center line should be ≤1mm. The height of the cooling water pipe assembly from the surface of the steel plate should be about 150mm, and the angle error should be ≤0.5°. The position sensor signal line should use shielded twisted pair cable with a grounding resistance of ≤4Ω. A UPS uninterruptible power supply should be configured. The suspended solids in the water supply system should be ≤5mg / L. A bypass pipeline and a backup electric regulating valve should be installed. 2) Basic parameter settings: In the PLC control system, set the rolling speed to 0.5-3.8m / s, steel plate thickness to 8-60mm, cooling temperature to 850-950℃, cooling intensity to strong cooling 150m³ / h, medium cooling 100m³ / h, and weak cooling 20m³ / h, set the steel plate head and tail clearance zone to 500mm from the head and tail, electric regulating valve response time ≤0.3 seconds, control accuracy ±1%, and PLC sampling period 50ms; 3) Position and speed detection: The rolling position of the steel plate is detected in real time by a position sensor, and the main drive speed of the rolling mill is collected by an encoder and transmitted to the PLC control system in real time; 4) Dynamic avoidance and time node calculation: The PLC control system accurately calculates the time node when the head and tail of the steel plate reach the cooling zone based on the steel plate length and rolling speed. When the edge of the steel plate enters the preset avoidance zone, the PLC outputs a control signal, and the electric regulating valve completes the opening adjustment within 0.3 seconds. 5) Gradient cooling control: When the middle part of the steel plate passes through the cooling zone, a strong cooling mode is adopted. The transition area outside the head and tail avoidance zone is subjected to linear gradual cooling from strong cooling to weak cooling. The head and tail avoidance zone adopts a weak cooling mode. For every 5mm increase in steel plate thickness, the cooling water volume increases by 15%. For every 0.5m / s increase in rolling speed, the avoidance zone is extended by 100mm. 6) Closed-loop feedback control: The position sensor and temperature detection element collect data and transmit it to the PLC in real time. The PLC dynamically adjusts the opening of the electric regulating valve according to the actual temperature difference to ensure that the temperature difference between the head, middle and tail of the steel plate is controlled within 10℃.

[0006] Furthermore, the cooling water pipe in step 1) is a ring-shaped stainless steel water pipe with a diameter of φ200mm and a wall thickness of 8mm. The surface has spirally arranged φ10mm water outlet holes. The water nozzles at the water outlets are equipped with shut-off valves, which can realize independent control of individual water nozzles. The water pipe is connected to the main water supply system through a connector, which is convenient for maintenance and replacement.

[0007] The electric regulating valve in step 1) is a DN200 electric ball valve equipped with a position feedback sensor, which can achieve stepless adjustment of 0-100% opening degree. The backup electric regulating valve can be automatically put into use within 0.5 seconds when the main valve fails.

[0008] In step 1), the guide frame is fixed to the mill outlet side with bolts, and the water supply system is equipped with a bypass pipe to facilitate the maintenance of guide lubrication during maintenance.

[0009] In step 4), the position of the steel plate is detected in real time by high-temperature thermal inspection before the rolling mill. Combined with the rolling pass length data, the position status of the head and tail of the steel plate is accurately determined.

[0010] The mill guide cooling water pipe device consists of a guide frame, cooling water pipes, an electric regulating valve, a position sensor, and a PLC control system. The cooling water pipes are integrated into the guide frame, the electric regulating valve is connected to the cooling water pipes, the position sensor is connected to the PLC control system via signal, and the PLC control system is electrically connected to the electric regulating valve. The entire device is integrated into the mill rear guide system, forming a closed-loop temperature control system.

[0011] The PLC control system uses a Siemens S7-1500 PLC, which works in conjunction with the electric regulating valve and position sensor to achieve precise time and space control of the cooling water flow.

[0012] This invention is applicable to rolling production lines for high-strength steel products such as medium and heavy plates and wire rods, and is especially suitable for the production of high-strength steel for military and energy equipment.

[0013] The guide cooling module of this invention uses a ring-shaped stainless steel cooling water pipe with a diameter of φ200mm and a wall thickness of 8mm. The surface has spirally arranged φ10mm water outlet holes to ensure that the cooling water evenly covers the surface of the steel plate. The water pipe is connected to the main water supply system through a connector for easy maintenance and replacement.

[0014] The electric regulating system in this invention uses a DN200 electric ball valve as the electric regulating valve, with a response time of ≤0.3 seconds. Equipped with a position feedback sensor, the valve control accuracy reaches ±1%, and it can achieve stepless adjustment of 0-100% opening degree. It forms a control system with a Siemens S7-1500 PLC, with a sampling period of 50ms, to achieve precise control of cooling water flow.

[0015] The obstacle avoidance control mechanism in this invention combines high-temperature thermal detectors and encoders before the rolling mill to monitor the steel plate position, rolling speed, and head and tail positions in real time. When the edge of the steel plate is detected to enter the preset obstacle avoidance zone, the PLC control system quickly outputs a control signal, and the electric regulating valve achieves millisecond-level action to complete the timely adjustment of the cooling water flow. By obtaining the main drive speed of the rolling mill through the encoder and combining it with the steel plate length data, the PLC control system accurately calculates the time node when the head and tail of the steel plate reach the cooling zone and issues a pre-control command in advance to achieve precise dynamic obstacle avoidance cooling of the head and tail of the steel plate. For example, when the rolling speed is 2m / s and the steel plate length is 12m, the system issues a pre-opening command 0.25 seconds after the head of the steel plate reaches the cooling zone. The solution to the problem of uneven temperature at the beginning and end of the steel plate rolling process is to achieve precise control of cooling water flow and dynamic avoidance cooling at the beginning and end of the steel plate through the deep integration of mechanical structure and intelligent control technology. This effectively reduces the temperature difference between the beginning, middle and end of the steel plate rolling process, improves the temperature uniformity of the steel plate, increases the steel yield, reduces production energy consumption and resource waste, and meets the quality requirements of high-end high-strength steel production. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments.

[0017] Example: This example focuses on the uniform temperature control at the beginning and end of the rolling process of a 25mm thick high-strength steel plate. The control method of this invention is used, with the rolling speed set at 2.5m / s and the initial cooling temperature at 900℃. The specific implementation steps are as follows: 1. Installation and commissioning of the device: Install the cooling water pipe device of the guide in the guide system after the rolling mill. The guide frame is fixed on the exit side of the rolling mill. The deviation between the center line of the cooling water pipe and the rolling center line is 0.8mm. The height of the water pipe from the surface of the steel plate is 150mm and the angle error is 0.3°. The position sensor signal line uses shielded twisted pair cable with a grounding resistance of 3.5Ω. UPS uninterruptible power supply is configured. The water quality of the water supply system has suspended solids of 3mg / L. Bypass pipe and backup electric regulating valve are set.

[0018] 2. Parameter settings: Set the basic parameters in the PLC control system: rolling speed 2.5m / s, steel plate thickness 25mm, cooling temperature 900℃; cooling intensity: strong cooling 150m³ / h, weak cooling 20m³ / h. Since the steel plate thickness is 25mm, it is increased by 5mm from the basic 20mm, and the cooling water volume is increased by 15%, with the strong cooling water volume adjusted to 172.5m³ / h; the rolling speed is 2.5m / s, which is increased by 2m / s from the basic 0.5m / s, and the head and tail avoidance zone is extended by 400mm, set to 900mm from the head and tail of the steel plate.

[0019] 3. Detection and Calculation: The position of the steel plate is detected by high-temperature heat detection before the rolling mill. The encoder collects the rolling speed of 2.5m / s. The PLC control system calculates the time node when the head of the steel plate reaches the cooling zone based on the length of the steel plate of 15m and issues a pre-control command in advance.

[0020] 4. Gradient Cooling and Clearance: When the middle of the steel plate passes through the cooling zone, the electric regulating valve is fully open, and the cooling water flow rate is 172.5 m³ / h for strong cooling; when the steel plate enters the transition area outside the 900 mm clearance zone at the head and tail, the cooling water flow rate is linearly reduced from 172.5 m³ / h to 20 m³ / h; when the head and tail of the steel plate enter the 900 mm clearance zone, the weak cooling mode is maintained, with a flow rate of 20 m³ / h.

[0021] 5. Closed-loop feedback: The position sensor and temperature detection element provide real-time feedback data, and the PLC control system dynamically adjusts the opening of the electric regulating valve. Ultimately, the temperature difference between the head, middle and tail of the 25mm thick steel plate after rolling is controlled at 8℃, which is much lower than the 50℃ temperature difference of the traditional process.

[0022] The embodiments of the present invention solve the problem of uneven temperature at the beginning and end of the steel plate rolling process by describing the above steps, achieving significant technical, quality, and economic benefits: Temperature uniformity is greatly improved: the temperature difference between the beginning, middle and end of the steel plate rolling process is reduced from 50℃ in the traditional process to less than 10℃, the temperature control accuracy is significantly improved, and the temperature uniformity requirements of high-end high-strength steel production are met.

[0023] Steel plate performance stability optimization: The standard deviation of elongation of 25mm thick steel plate has been reduced from 4.5% to 1.8%, and the stability of mechanical properties such as yield strength of steel plate has been greatly improved, fully meeting the requirements of API standards.

[0024] Significantly improved production efficiency: The elimination of the "transition length" cutting problem in the traditional cooling system increased the steel yield by 0.6 percentage points, resulting in an annual increase in benefits of 3 million yuan based on an annual production of 500,000 tons of high-strength steel; reduced metal removal by 1.2%, resulting in annual cost savings of 3.6 million yuan based on an average high-strength steel price of 6,000 yuan / ton; and improved product grade rate by 8%, increasing the added value of high-quality products by 200 yuan / ton, resulting in an annual increase in benefits of approximately 10 million yuan.

[0025] Outstanding energy-saving and carbon-reduction effects: It does not require the use of high-energy-consuming induction heating technology, saving 1.25 million kWh of electricity and reducing carbon emissions by 980 tons per year, which is in line with the industry development trend of green production.

[0026] The core of this invention lies in the linkage between the cooling water pipe device of the rolling mill rear guide system and the PLC control system to achieve precise spatiotemporal control of cooling water flow and dynamic avoidance cooling of the head and tail of the steel plate. The above embodiments are only preferred embodiments of this invention and are not intended to limit the invention.

[0027] In practical production applications, control parameters such as cooling water volume, clearance zone range, and cooling intensity can be flexibly adjusted according to the specifications, material, and rolling speed of the rolled steel plate, all of which fall within the protection scope of this invention. Furthermore, core components of this device, such as the electric regulating valve and PLC control system, can be replaced with equivalent equipment based on production needs. As long as the control method and technical effects of this invention can be achieved, they all fall within the protection scope of this invention.

[0028] The method of the present invention is simple to operate, the device is easy to install and maintain, and can be directly integrated into the existing rolling mill rear guide system without large-scale modification of the existing rolling production line. The modification cost is low and the application prospects are broad.

Claims

1. A method for controlling the uniform temperature at both the beginning and end of the rolling process of high-strength steel plates, characterized in that: This is achieved using a mill guide cooling water pipe device, which consists of a guide frame, cooling water pipes, electric regulating valves, position sensors, and a PLC control system. This device is integrated into the mill's rear guide system, forming a closed-loop temperature control system. The specific control method includes the following steps: 1) Installation and commissioning of the device: Fix the guide frame on the exit side of the rolling mill. The deviation between the center line of the cooling water pipe and the rolling center line should be ≤1mm. The height of the cooling water pipe assembly from the surface of the steel plate should be about 150mm, and the angle error should be ≤0.5°. The position sensor signal line should use shielded twisted pair cable with a grounding resistance of ≤4Ω. A UPS uninterruptible power supply should be configured. The suspended solids in the water supply system should be ≤5mg / L. A bypass pipeline and a backup electric regulating valve should be installed. 2) Basic parameter settings: In the PLC control system, set the rolling speed to 0.5-3.8m / s, steel plate thickness to 8-60mm, cooling temperature to 850-950℃, cooling intensity to strong cooling 150m³ / h, medium cooling 100m³ / h, and weak cooling 20m³ / h, set the steel plate head and tail clearance zone to 500mm from the head and tail, electric regulating valve response time ≤0.3 seconds, control accuracy ±1%, and PLC sampling period 50ms; 3) Position and speed detection: The rolling position of the steel plate is detected in real time by a position sensor, and the main drive speed of the rolling mill is collected by an encoder and transmitted to the PLC control system in real time; 4) Dynamic avoidance and time node calculation: The PLC control system accurately calculates the time node when the head and tail of the steel plate reach the cooling zone based on the steel plate length and rolling speed. When the edge of the steel plate enters the preset avoidance zone, the PLC outputs a control signal, and the electric regulating valve completes the opening adjustment within 0.3 seconds. 5) Gradient cooling control: When the middle part of the steel plate passes through the cooling zone, a strong cooling mode is adopted. The transition area outside the head and tail avoidance zone is subjected to linear gradual cooling from strong cooling to weak cooling. The head and tail avoidance zone adopts a weak cooling mode. For every 5mm increase in steel plate thickness, the cooling water volume increases by 15%. For every 0.5m / s increase in rolling speed, the avoidance zone is extended by 100mm. 6) Closed-loop feedback control: The position sensor and temperature detection element collect data and transmit it to the PLC in real time. The PLC dynamically adjusts the opening of the electric regulating valve according to the actual temperature difference to ensure that the temperature difference between the head, middle and tail of the steel plate is controlled within 10℃.

2. The method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: The cooling water pipe in step 1) is a ring-shaped stainless steel water pipe with a diameter of φ200mm and a wall thickness of 8mm. The surface has spirally arranged φ10mm water outlet holes. The water nozzles at the water outlets are equipped with shut-off valves, which can realize independent control of individual water nozzles. The water pipe is connected to the main water supply system through a connector for easy maintenance and replacement.

3. The method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: The electric regulating valve in step 1) is a DN200 electric ball valve equipped with a position feedback sensor, which can achieve stepless adjustment of 0-100% opening degree. The backup electric regulating valve can be automatically put into use within 0.5 seconds when the main valve fails.

4. The method for controlling the uniform temperature at the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: In step 1), the guide frame is fixed to the mill outlet side with bolts, and the water supply system is equipped with a bypass pipe to facilitate the maintenance of guide lubrication during maintenance.

5. The method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: In step 4), the position of the steel plate is detected in real time by high-temperature thermal inspection before the rolling mill. Combined with the rolling pass length data, the position status of the head and tail of the steel plate is accurately determined.

6. The method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: The mill guide cooling water pipe device consists of a guide frame, cooling water pipes, an electric regulating valve, a position sensor, and a PLC control system. The cooling water pipes are integrated into the guide frame, the electric regulating valve is connected to the cooling water pipes, the position sensor is connected to the PLC control system via signal, and the PLC control system is electrically connected to the electric regulating valve. The entire device is integrated into the mill rear guide system, forming a closed-loop temperature control system.

7. The method for controlling the uniform temperature at both the beginning and end of the high-strength steel plate rolling process according to claim 1, characterized in that: The PLC control system uses a Siemens S7-1500 PLC, which works in conjunction with the electric regulating valve and position sensor to achieve precise time and space control of the cooling water flow.