CN112122361A - Laminar cooling control method for preventing medium-high carbon steel from cracking - Google Patents
Laminar cooling control method for preventing medium-high carbon steel from cracking Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
- B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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Abstract
The invention relates to a laminar cooling control method for preventing cracking of medium-high carbon steel, which mainly solves the defect of cracking on the surface of strip steel caused by uneven stress due to phase change time difference caused by uneven local cooling in the conventional laminar cooling process of the steel, and can reach the coiling temperature at a higher cooling rate so as to obtain a hot-rolled product with excellent structure and performance. Therefore, a cooling path and a model control method are required in which the cooling process is uniform and rapid.
Description
Technical Field
The invention relates to a control method, in particular to a laminar cooling control method for preventing medium-high carbon steel from cracking, and belongs to the technical field of hot rolling production.
Background
The high carbon steel with omega (C) being more than or equal to 0.45 percent has high strength, high hardness and higher tensile strength and hardness, can obtain good mechanical property after heat treatment, is commonly used in the field of fine blanking processing, and can obtain fine blanking parts with higher dimensional precision, smoother blanking surface, less warpage and better interchangeability than the common blanking parts. The purpose of controlled cooling after rolling of this type of steel is to prevent austenite grains from growing large after deformation, and because of the high carbon content, the microstructure produced after normal cooling is ferrite and pearlite, with pearlite as the main component. The steel grade has the following characteristics in the laminar cooling process: (1) the higher cooling rate can be reduced so as to prevent the precipitation amount and the reduction level of the reticular carbide, maintain the solid solution state of the carbide, achieve the aim of solid solution strengthening, reduce the size of pearlite pellets, improve the appearance of pearlite, the interlayer spacing and the like, and further improve the performance of steel; (2) the heat exchange area when laminar cooling water impacts the steel plate is divided into a single-phase forced convection area, a nucleate boiling and transition boiling area, a film boiling area, a small liquid state gathering area and an air cooling radiation area, so that different heat transfer phenomena are caused at different parts, uneven cooling of the steel strip is easily caused, phase change time difference is caused when the local cooling speed of the steel strip is too high, internal stress is generated, and the steel strip can crack when the internal stress exceeds the tensile strength value of the material. Based on the characteristics, the steel grade is required to ensure a sufficiently rapid cooling rate in the laminar cooling process, and surface cracking caused by the local rapid cooling of the strip steel is avoided, so that the cooling control method needs to be optimized and innovated.
Chinese patent CN 109321729A, "rolling method of high carbon steel", mainly provides a rolling method of high carbon steel, the laminar cooling process that the process step involves is divided into two sections, front and back, the cooling rate of the front section is 30-50 ℃/s, the cooling rate of the back section is 50-200 ℃/s, the intermediate temperature is 450-550 ℃, wherein the intermediate temperature refers to the temperature when the front section is cooled off and the back section is cooled off; the coiling temperature is 50-200 ℃, in the laminar cooling process, the cooling speed of the laminar flow front section cooling is controlled, so that pearlite phase transformation rapidly occurs at a lower temperature of 490-560 ℃, lamellar pearlite with the lamellar spacing being less than or equal to 200nm is obtained, austenite is completely transformed in the front section cooling, the high-speed rear section cooling speed and low-temperature coiling enable the temperature of the steel coil to be uniformly and rapidly reduced to be below 200 ℃, the steel coil is prevented from cracking, the direct delivery condition is met, and the turnover rate of the steel coil warehouse is improved. The method is greatly different from the purposes and ideas of the invention.
Chinese patent CN 104278201B, "preparation method of high-carbon steel with good cold formability", discloses a preparation method of high-carbon steel with good cold formability, which relates to the laminar cooling adopting front-stage rapid cooling with a cooling speed of 100 ℃/s, a laminar cooling finishing temperature of 560 ℃, a rear-stage cooling rate of 15 ℃/s, a coiling temperature of 550 ℃, and does not relate to the problem of avoiding local supercooling in the rapid cooling process, which is different from the problem solved by the method.
Disclosure of Invention
The invention provides a laminar cooling control method for preventing medium-high carbon steel from cracking aiming at the problems in the prior art, and the technical scheme mainly solves the defect of band steel surface cracking caused by stress nonuniformity due to phase change time difference generated by nonuniform local cooling in the conventional laminar cooling process of the steel type, and can reach the coiling temperature at a higher cooling rate so as to obtain a hot-rolled product with excellent structure and performance. Therefore, a cooling path and a model control method are required in which the cooling process is uniform and rapid.
In order to achieve the purpose, the technical scheme of the invention is that the laminar cooling control method for preventing medium-high carbon steel from cracking is characterized by comprising the following steps:
1) determining a designed cooling process path in a coiling process window, and formulating a corresponding cooling control code; 2) making a rolling line speed system; 3) the CTC model pre-calculates the laminar cooling process of the strip steel according to the predicted thickness and temperature of the strip steel head at the outlet of the strip steel rolling mill; 4) continuously measuring and determining the full-length actual measurement thickness of the strip steel in the model input variable through an L1 basic automatic control system; 5) continuously measuring and determining the actual measurement temperature of the full length of the strip steel at a finish rolling outlet in the input variables of the model through an L1 basic automatic control system; 6) performing feedforward calculation by a CTC model according to the steps 1), 2), 3), 4) and 5) in combination with the coiling temperature target value, and setting the opening position of each section of laminar cooling valve of the strip steel; 7) continuously measuring the temperature of the laminar flow outlet by an L1 basic automatic control system, and performing temperature feedback control; 8) when the tail of the strip steel section reaches the coiling temperature measuring instrument, the feedback control program is used for exciting, the layer cooling efficiency self-learning and the section self-adaptive correction are carried out according to the temperature control result, the cooling process of the whole strip steel is completed through a cooling model issued by an L2 process control computer system, and a closed-loop control is formed; 9) and detecting the performance and the structure of the rolled strip steel, and solidifying or correcting the cooling control parameters.
As an improvement of the invention, the step 1) is specifically operated as follows: according to the existing laminar flow cooling device: there are 15 groups of cooling banks, wherein bank1 ~ 3 are strong cold I district, 16 collector pipes respectively on the upper and lower, 16 pneumatic butterfly valves respectively on the upper and lower, upward flow 116m3H, lower flow 70(58) m3H; banks 4-8 are used for conventional coolingThe area comprises 8 upper collecting pipes, 16 lower collecting pipes, 8 upper and lower pneumatic butterfly valves and an upper flow rate of 116m3H, lower flow 58m3H; banks 9 ~ 13 are strong cold II district, 16 respectively collector pipes on the upper and lower, 16 respectively pneumatic butterfly valves on the upper and lower, upward flow 116m3H, lower flow 70(58) m3H; banks 14-15 are feedback cooling areas, each of the upper and lower 16 collecting pipes has an upper flow rate of 58m3H, lower flow 58m3The method comprises the following steps that (h), banks 1-13 are rough adjustment areas, banks 14-15 are fine adjustment areas, 16 groups of side spray valves are arranged, the side spray pressure is 1.2Mpa, the side spray valves are switched on when the head of a strip steel passes through a nozzle and a cooling area begins to cool, the side spray valves are switched off after the tail of the strip steel passes through the nozzle and the cooling area is switched off, when the corresponding cooling valves are used, the side spray valves of each group are switched on and off according to the tracking of the strip steel, the side spray valves are switched on and off through pneumatic control, banks 1, 3, 5, 7, 9, 11 and 13 are set as water cooling valve groups which are opened preferentially, banks 2, 4, 6, 8, 10, 12 and 14 are set as tail end opening valves, so that the air cooling purpose is achieved, namely: the strip steel is subjected to finish rolling, then is subjected to water cooling, is fully cooled in a water-cooling header area, and then enters an air cooling area of bank2, wherein the strip steel is subjected to heat conduction by itself in the area, the temperature tends to be uniform, and then enters a water cooling area of bank3, and the like, so that the cooling strategy of alternating water cooling and air cooling is realized.
As an improvement of the present invention, the step 2) specifically operates as follows: according to the thickness of the strip steel and the finish rolling temperature, a speed schedule is established: under the control condition that the speed system meets the finish rolling temperature, the opening of cooling water between frames is avoided, the rolling is carried out by a uniform acceleration system with smaller acceleration value, the given values of the first adding and the second adding are 0.01m/s2, the CTC model can calculate the time of a strip steel section passing through a valve sequence according to the TVD section data of the strip steel, and the time of a certain section of the strip steel passing through a valve or a valve sequence is calculated according to the TVD data of the strip steel to be used as a time parameter for calculating the cooling temperature drop. When the time of a certain strip steel section passing through a valve group area is calculated, the strip steel head deviation treatment is carried out according to the following steps: the starting valve offset x1 is the length of strip passing through the EMP before the starting valve position + F7 to EMP distance +. The end valve offset x2 is x1+ the time t for a valve block section of the valve block length to pass through a valve block section is the time between x1 and x2 on the TVD line graph of the strip.
As an improvement of the present invention, the step 3) specifically operates as follows: the CTC model calculates the laminar cooling process of the strip steel according to the predicted thickness, temperature and speed of the strip steel head at the outlet of the strip steel rolling mill, and presets laminar cooling nozzles according to the designed cooling mode. And calculating the temperature drop of the strip steel according to the predicted thickness and temperature of the strip steel at the outlet of the rolling mill, the head cooling time and the required coiling target temperature and the maximum valve opening mode, and obtaining a set valve array.
As an improvement of the present invention, the step 4) specifically operates as follows: the thickness is measured by a thickness detector at a finish rolling outlet, the measured thickness of the full length of the strip steel is continuously measured by an L1 basic automatic control system, and the measured thickness is transmitted to an L2 process control computer system to be used as a thickness variable input by a CTC model.
As an improvement of the present invention, the step 5) specifically operates as follows: and detecting the actual measurement temperature of the full length of the strip steel by a pyrometer at a finish rolling outlet, and continuously transmitting the actual measurement temperature to an L2 process control computer system by an L1 basic automatic control system to be used as a temperature variable input by a CTC model.
As a modification of the present invention, the step 6) specifically operates as follows: and calculating the coiling temperature of the current section by the CTC model according to the actual thickness and temperature of the current section at the outlet of the rolling mill, the cooling time of the current section and a set valve, comparing the coiling temperature with the required coiling target temperature, and correspondingly adjusting the opening of the valve according to the deviation to obtain a set valve array.
As an improvement of the present invention, the step 7) specifically operates as follows: the temperature of the laminar flow outlet was continuously measured by an L1 basic automated control system, the model started the function of the feedback program, and the valve array in the feedback zone was controlled according to the deviation of the actual measured value from the target value of the coiling temperature.
As a modification of the present invention, the step 8) specifically operates as follows: when the tail of the strip steel section reaches the coiling temperature measuring instrument, the feedback control program is used for exciting, learning the genetic correction coefficient, carrying out section-to-section self-adaptation and correcting the rest part of the strip steel.
As a modification of the invention, the step 9) takes a representative sample plate of the coiled steel strip to carry out performance and structure detection, if the performance is qualified, ferrite and pearlite structures are obtained, and the cooling path is fixed.
Compared with the prior art, the invention has the following advantages that the technical scheme develops the method of the cooling path of water-cooling and air-cooling alternative cooling in the 'coiling process window' of the high-carbon fine blanking steel. Aiming at the problems that the prior art is limited by the water sweeping effect capability on the spot of the laminar cooling and the local cooling speed is too high due to the accumulated water on the surface of the strip steel, the phase change of the strip steel is time-lag, the stress is uneven and the strip steel is cracked, a water-air alternative cooling path method is developed aiming at the uneven cooling of the strip steel in the laminar flow region, so that the integral temperature of the strip steel tends to be even by the heat conduction of the strip steel when the strip steel is cooled to another relatively high temperature in a high temperature stage, and then the strip steel is cooled in the next step to obtain even ferrite and pearlite structures.
Drawings
FIG. 1 is a schematic view of a plum steel 1780 production line laminar cooling arrangement;
fig. 2 is a schematic diagram of water-cooling and air-cooling alternating cooling.
The specific implementation mode is as follows:
for the purpose of enhancing an understanding of the present invention, the present embodiment will be described in detail below with reference to the accompanying drawings.
Example 1:
the invention discloses a control method for uniform and rapid cooling in a laminar cooling process of high-carbon fine blanking tool steel, which comprises the following steps of:
(1) according to the existing laminar flow cooling device: the cooling strategy data sets banks 1, 3, 5, 7, 9, 11 and 13 as the preferential opening water-cooled valve group and banks 2, 4, 6, 8, 10, 12 and 14 as the tail end opening valves.
(2) According to the thickness of the strip steel and the finish rolling temperature, a speed schedule is established: the speed system avoids the cooling water between the frames from being opened under the control condition of meeting the finish rolling temperature, and micro-addition is adoptedRolling at uniform acceleration system with given values of first acceleration and second acceleration of 0.01m/s2The CTC model can calculate the time of a strip steel segment passing through a valve sequence according to the TVD segment data of the strip steel
(3) After the CTC model determines cooling strategy data, according to a maximum valve opening mode, a cooling pre-calculation module predicts the cooling capacity required by the strip steel at the maximum running speed according to the preset rolling speed of the strip steel, evaluates whether the cooling capacity of the whole laminar cooling can meet the process requirement, displays the estimated coiling temperature on a laminar cooling picture as an operation guide, and calculates the head valve of the strip steel according to material information in PDI, the target thickness of a finished product, the target coiling temperature and the like after the strip steel cooling capacity is confirmed.
(3) The thickness is measured by a thickness detector at a finish rolling outlet, the measured thickness of the full length of the strip steel is continuously measured by an L1 basic automatic control system, and the measured thickness is transmitted to an L2 process control computer system to be used as a thickness variable input by a CTC model.
(4) And detecting the actual measurement temperature of the full length of the strip steel by a pyrometer at a finish rolling outlet, and continuously transmitting the actual measurement temperature to an L2 process control computer system by an L1 basic automatic control system to be used as a temperature variable input by a CTC model.
(5) The running speed of the strip steel calculated by the encoder is continuously transmitted to the L2 process control computer system by the L1 basic automatic control system and is used as a speed variable input by the CTC model.
(6) And calculating the coiling temperature of the current section by the CTC model according to the actual thickness and temperature of the current section at the outlet of the rolling mill, the cooling time of the current section and a set valve, comparing the coiling temperature with the required coiling target temperature, and correspondingly adjusting the opening of the valve according to the deviation to obtain a set valve array.
(7) The temperature of the laminar flow outlet was continuously measured by an L1 basic automated control system, the model started the function of the feedback program, and the valve array in the feedback zone was controlled according to the deviation of the actual measured value from the target value of the coiling temperature.
(8) When the tail of the strip steel section reaches the coiling temperature measuring instrument, the feedback control program is used for exciting, learning the genetic correction coefficient, carrying out section-to-section self-adaptation and correcting the rest part of the strip steel.
(9) And (4) taking a representative sample plate of the coiled strip steel for performance and structure detection, if the performance is qualified, obtaining a ferrite and pearlite structure, and fixing the cooling path.
Application example 1:
taking 65Mn of 5.5 x 1250mm as an example of the finished product specification, the water-air alternative cooling steps are as follows:
1. the chemical composition is shown in table 1:
TABLE 165 Mn chemical composition (mass fraction,%)
| C | Si | Mn | P | S | Cr | Mo | Al |
| 0.65 | 0.24 | 1 | 0.01 | 0.0017 | 0.2185 | 0.0018 | 0.0223 |
The balance being Fe.
2. Designing a strip steel speed system, designing a threading speed of 5.3m/s and setting values of a first acceleration and a second acceleration of 0.01m/s according to the target value 875 ℃ of the finish rolling temperature of the steel grade with the specification2。
3. And calculating the laminar cooling process of the strip steel according to the predicted thickness, temperature and speed of the outlet of the strip steel rolling mill, performing pre-calculation by using a CT (computed tomography) model, and controlling a laminar flow valve to pre-boil water when F2 bites the steel. The pre-boiling water valves are bank1 and bank 3.
4. And performing feedforward calculation on the laminar cooling process of the strip steel according to the actually measured thickness, temperature and speed, performing feedforward calculation on the CT model, and performing real-time adjustment on the refrigerating valve array.
5. By measuring the temperature of the laminar flow outlet, the model starts the function of the feedback program, controls the valve array of the feedback area according to the deviation of the actual measurement value and the target value of the coiling temperature, and starts the BANK 14.
6. And finishing the laminar flow cooling process, coiling the strip steel, using a CTC model, and correcting the self-learning genetic coefficient.
7. And taking a representative sample of the coiled strip steel for performance organization detection.
Results of micro-hardness structure of strip steels in Table 265 Mn
TABLE 365 Mn strip steel mechanical property results
| Yield strength | Tensile strength | Elongation percentage |
| 581 | 876 | 18.5 |
| 539 | 900 | 19 |
| 516 | 865 | 17.5 |
。
Example 2:
taking C45E with the specification of 8.0 x 1290mm as an example, the water-air alternating cooling steps are as follows:
1. the chemical composition is shown in table 1:
TABLE 4C 45E chemical composition (mass fraction,%)
| C | Si | Mn | P | S | Cr | Mo | Al |
| 0.45 | 0.2 | 0.64 | 0.012 | 0.0004 | 0.25 | 0.0016 | 0.03 |
The balance being Fe.
2. Designing a strip steel speed system, designing a threading speed of 3.4m/s and a first acceleration and a second acceleration given value of 0.01m/s according to the target value of the finish rolling temperature of the thick steel grade of 850 DEG C2。
3. And calculating the laminar cooling process of the strip steel according to the predicted thickness, temperature and speed of the outlet of the strip steel rolling mill, performing pre-calculation by using a CT (computed tomography) model, and controlling a laminar flow valve to pre-boil water when F2 bites the steel. The pre-boiling water valves are bank1 and bank 3.
4. And performing feedforward calculation on the laminar cooling process of the strip steel according to the actually measured thickness, temperature and speed, performing feedforward calculation on the CT model, and performing real-time adjustment on the refrigerating valve array.
5. By measuring the temperature of the laminar flow outlet, the model starts the function of the feedback program, controls the valve array of the feedback area according to the deviation of the actual measurement value and the target value of the coiling temperature, and starts the BANK 14.
6. And finishing the laminar flow cooling process, coiling the strip steel, using a CTC model, and correcting the self-learning genetic coefficient.
7. Taking a representative sample of the coiled strip steel for performance organization detection
TABLE 5 micro-hardness structure results for C45E strip
TABLE 6 mechanical Property results for C45E strip
| Yield strength | Tensile strength | Elongation percentage |
| 447 | 788 | 21.5 |
| 458 | 791 | 22.5 |
| 486 | 777 | 20.5 |
。
It should be noted that the above-mentioned embodiments are not intended to limit the scope of the present invention, and all equivalent modifications and substitutions based on the above-mentioned technical solutions are within the scope of the present invention as defined in the claims.
Claims (10)
1. A laminar cooling control method for preventing cracking of medium-high carbon steel is characterized by comprising the following steps:
1) determining a designed cooling process path in a coiling process window, and formulating a corresponding cooling control code; 2) making a rolling line speed system; 3) the CTC model pre-calculates the laminar cooling process of the strip steel according to the predicted thickness and temperature of the strip steel head at the outlet of the strip steel rolling mill; 4) continuously measuring and determining the full-length actual measurement thickness of the strip steel in the model input variable through an L1 basic automatic control system; 5) continuously measuring and determining the actual measurement temperature of the full length of the strip steel at a finish rolling outlet in the input variables of the model through an L1 basic automatic control system; 6) performing feedforward calculation by a CTC model according to the steps 1), 2), 3), 4) and 5) in combination with the coiling temperature target value, and setting the opening position of each section of laminar cooling valve of the strip steel; 7) continuously measuring the temperature of the laminar flow outlet by an L1 basic automatic control system, and performing temperature feedback control; 8) when the tail of the strip steel section reaches the coiling temperature measuring instrument, the strip steel section is excited by a feedback control program, and layer cooling efficiency self-learning is carried out according to a temperature control result, so that the whole strip steel is cooled by a cooling model issued by an L2 process control computer system, and a closed-loop control is formed; 9) and detecting the performance and the structure of the rolled strip steel, and solidifying or correcting the cooling control parameters.
2. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 1, characterized in that the laminar cooling control method is used for preventing cracking of medium-high carbon steel
The step 1) specifically comprises the following operations: according to the existing laminar flow cooling device: there are 15 groups of cooling banks, wherein bank1 ~ 3 are strong cold I district, 16 collector pipes respectively on the upper and lower, 16 pneumatic butterfly valves respectively on the upper and lower, upward flow 116m3H, lower flow 70(58) m3H; the banks 4 ~ 8 are conventional cooling zones, 8 upper headers, 16 lower headers, 8 pneumatic butterfly valves of upper and lower each, and the upper flow is 116m3H, lower flow 58m3H; banks 9 ~ 13 are strong cold II district, 16 respectively collector pipes on the upper and lower, 16 respectively pneumatic butterfly valves on the upper and lower, upward flow 116m3H, lower flow 70(58) m3H; banks 14-15 are feedback cooling areas, each of the upper and lower 16 collecting pipes has an upper flow rate of 58m3H, lower flow 58m3The Bank 1-13 is a coarse adjustment area, the Bank 14-15 is a fine adjustment area, 16 groups of side spray valves are arranged, the side spray pressure is 1.2MPa, and the side spray valves are arranged when the head of the strip steel passes through the spray nozzles and the cooling area begins to coolAnd when the corresponding cooling valves are put into use, each group of side spraying valves are switched on and off according to the tracking of the strip steel, the side spraying valves are switched on and off through pneumatic control, the bank1, 3, 5, 7, 9, 11 and 13 are set as a group of water-cooling valves which are opened preferentially, and the bank2, 4, 6, 8, 10, 12 and 14 are set as tail end opening valves, so that the purpose of air cooling is achieved, namely: the strip steel is subjected to finish rolling, then is subjected to water cooling, is fully cooled in a water-cooling header area, and then enters an air cooling area of bank2, wherein the strip steel is subjected to heat conduction by itself in the area, the temperature tends to be uniform, and then enters a water cooling area of bank3, and the like, so that the cooling strategy of alternating water cooling and air cooling is realized.
3. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 1, characterized in that the step 2) is specifically operated as follows: according to the thickness of the strip steel and the finish rolling temperature, a speed schedule is established: under the control condition that the speed system meets the final rolling temperature, the opening of cooling water between frames is avoided, the rolling is carried out by a uniform acceleration system with smaller acceleration value, the first adding and the second adding have given values of 0.01m/s2And the CTC model can calculate the time of one strip steel segment passing through a valve sequence according to the TVD segment data of the strip steel.
4. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 1, characterized in that the step 3) is specifically operated as follows: the CTC model calculates the laminar cooling process of the strip steel according to the predicted thickness, temperature and speed of the strip steel head at the outlet of the strip steel rolling mill, and presets laminar cooling nozzles according to the designed cooling mode.
5. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 3, characterized in that the step 4) is specifically operated as follows: the thickness is measured by a thickness detector at a finish rolling outlet, the measured thickness of the full length of the strip steel is continuously measured by an L1 basic automatic control system, and the measured thickness is transmitted to an L2 process control computer system to be used as a thickness variable input by a CTC model.
6. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 5, characterized in that the step 5) is specifically operated as follows: and detecting the actual measurement temperature of the full length of the strip steel by a pyrometer at a finish rolling outlet, and continuously transmitting the actual measurement temperature to an L2 process control computer system by an L1 basic automatic control system to be used as a temperature variable input by a CTC model.
7. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 6, characterized in that the step 6) is specifically operated as follows: and calculating the coiling temperature of the current section by the CTC model according to the actual thickness and temperature of the current section at the outlet of the rolling mill, the cooling time of the current section and a set valve, comparing the coiling temperature with the required coiling target temperature, and correspondingly adjusting the opening of the valve according to the deviation to obtain a set valve array.
8. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 7, characterized in that the step 7) is specifically operated as follows: the temperature of the laminar flow outlet was continuously measured by an L1 basic automated control system, the model started the function of the feedback program, and the valve array in the feedback zone was controlled according to the deviation of the actual measured value from the target value of the coiling temperature.
9. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 8, wherein the step 8) is specifically operated as follows: when the tail of the strip steel section reaches the coiling temperature measuring instrument, the feedback control program is used for exciting, learning the genetic correction coefficient, carrying out section-to-section self-adaptation and correcting the rest part of the strip steel.
10. The laminar cooling control method for preventing cracking of medium-high carbon steel according to claim 9, wherein the step 9) is to take a representative sample of the coiled steel strip to perform performance and structure detection, if the performance is qualified, obtain ferrite and pearlite structures, and fix the cooling path.
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