CN110653265B - Iron scale control method suitable for temperature change of hot-rolled intermediate billet - Google Patents
Iron scale control method suitable for temperature change of hot-rolled intermediate billet Download PDFInfo
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- CN110653265B CN110653265B CN201810685744.XA CN201810685744A CN110653265B CN 110653265 B CN110653265 B CN 110653265B CN 201810685744 A CN201810685744 A CN 201810685744A CN 110653265 B CN110653265 B CN 110653265B
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
- B21B38/006—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring temperature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B2201/00—Special rolling modes
- B21B2201/06—Thermomechanical rolling
Abstract
The invention relates to an iron scale control method suitable for temperature drop change of a hot-rolled intermediate billet, which comprises the steps of determining the state before improvement, gradually reducing second acceleration, determining whether the new second acceleration is qualified, and the like. The method for controlling the iron scale suitable for the temperature drop change of the hot-rolled intermediate billet provided by the invention can control the iron scale of the tail temperature system in the strip steel and can completely meet the quality requirement of products with high surface requirements.
Description
Technical Field
The invention relates to an iron scale control method suitable for temperature drop change of a hot-rolled intermediate billet, and belongs to the technical field of hot rolling.
Background
When the hot-rolled strip steel is produced, because the second flow of the roughing mill is far greater than that of the finishing mill, the time for the head of the intermediate billet to wait for the rolling of the finishing mill is short and the time for the tail of the intermediate billet to wait for the rolling of the finishing mill is long when the intermediate billet rolled by the roughing mill enters the finishing mill for rolling. Inconsistent wait times result in different temperature drops. When entering the finishing mill, the temperature drop of the head part is small, and gradually increases backwards until the temperature drop of the tail part reaches the maximum value. Therefore, the FME (finish rolling entry temperature) curve for an intermediate billet is a continuously decreasing curve, typically with a head temperature 50-100 ℃ higher than the tail.
In order to meet the requirements of product performance, the FDT (finish rolling outlet temperature) of the strip steel meets the requirements of target finish rolling temperature, the finish rolling speed is controlled to require accelerated rolling, and the difference of FME (frequency modulated annealing) is compensated by increasing the rolling speed and generating more deformation heat. In order to reduce energy loss, each hot rolling mill carries out work on reducing the temperature drop of the intermediate billet, so that the temperature difference between the head and the tail of the intermediate billet is gradually reduced. After the heat preservation effect of the intermediate billet is improved by the plum steel hot rolling 1780 production line, when a thin product with the thickness of less than 3.0mm is rolled, iron scales are generated at the tail part of the strip steel, and the surface quality requirement of a high-end user is not met.
Disclosure of Invention
The invention aims to solve the technical problems that: the method overcomes the defects of the technology and can quickly determine the second acceleration of the finishing mill after the heat preservation effect of the intermediate billet is improved, thereby reducing the scale.
In order to solve the technical problems, the technical scheme provided by the invention is as follows: a method for controlling the iron scale suitable for the temperature change of a hot-rolled intermediate billet comprises the following steps:
(1) determining the type and thickness specification of a target product;
(2) inquiring the used cooling water amount of 10 to 50 steel coils with the same type and the same thickness which are produced before, taking the maximum of the cooling water amounts as the maximum cooling water amount Mmax, and simultaneously calculating the average cooling water amount Mave;
(3) inquiring the head finish rolling outlet temperature of 10 to 50 coils of steel coils with the same type and the same thickness produced before, taking the maximum value as the maximum finish rolling outlet temperature FDTmax, and taking the minimum value as the minimum finish rolling outlet temperature FDTmin;
(4) inquiring the first acceleration a1 and the second acceleration a2 of the previously produced steel coil with the same type and the same thickness;
(5) let x1= a1, x2= a 2;
(6) let x = (x1+ x 2)/2; assigning a value of x to a second acceleration a2, i.e. let a2= x, produced as the second acceleration; monitoring the head finish rolling outlet temperature FDTj and the cooling water quantity Mj of the steel coil in the production process;
(7) if FDTj > FDTmax, reducing the temperature of the intermediate billet, and if FDTj < FDTmin, increasing the temperature of the intermediate billet until FDTmin < FDTj < FDTmax is met;
(8) if Mj < Mave, let x1= a2, and return to step 6; if Mj > Mmax, let x2= a2, return to step 6; if Mmax > Mj > Mave; the production test is completed and the current value of a2 is determined as the second acceleration.
The method for controlling the iron scale suitable for the temperature change of the hot-rolled intermediate billet provided by the invention can control the iron scale of the tail temperature system in the strip steel and can completely meet the quality requirement of products with high surface requirements.
Detailed Description
Examples
In the finish rolling process, the threading speed is generally configured according to the variety and specification to ensure stability, the threading is accelerated at a first acceleration after finishing to increase the finish rolling temperature, a target value is expected to be reached, the acceleration is started at a second acceleration after normal rolling to ensure the finish rolling temperature to be reached, and after the finish rolling temperature exceeds a certain range of the target value, closed-loop control is performed by opening cooling water between stands to ensure that the finish rolling temperature is within a standard, wherein the faster the speed is, the larger the temperature rise is, and the larger the cooling water amount between the stands is.
Because the heat preservation effect of the intermediate billet is changed, the tail temperature of the intermediate billet is higher than that before the improvement under the same condition, the strip steel temperature of each rack is improved differently under the same rolling speed condition, the finish rolling FME curve changes smoothly, and the slope (absolute value) becomes small. It is known that the acceleration of finish rolling temperature rise is to compensate for the decrease of FME, and the decrease of FME is small, so that the original acceleration is relatively large, and the final rolling temperature is increased. The rise of the finishing rolling temperature is adjusted and controlled by increasing the cooling water quantity between the stands, but the actual rolling temperature of each stand and the surface temperature of the strip blank between the stands still greatly rise, and when the temperature rises to the degree that the quality of the product is influenced by the generated iron scale, the product cannot meet the use of users.
The acceleration of thick specification products is small, the deformation of each rack is small, the generated deformation heat is small, and similar iron sheets can not be generated generally, but the strip threading speed of thin specification products is limited, the acceleration is high, the deformation degree of each rolling mill is large, the deformation heat is large, the strip temperature is possibly high, and the strip temperature is higher and higher along with the rolling along with the extension of the acceleration time, so that the tail of an important expression middle-tail iron sheet is more and more serious.
Analysis shows that the middle tail iron scale is caused by oxidation due to overhigh temperature in the strip rolling process, and the essential characteristic that the overhigh temperature is covered by large amount of cooling water between the stands.
The iron scale control method suitable for the temperature change of the hot-rolled intermediate billet mainly solves the problem that the tail temperature system iron scale in the strip steel influences the use of users with high surface quality requirements after the temperature drop of the intermediate billet is improved. Since the mid-tail has exceeded the range of first accelerations, it is indicated that the first acceleration a1 is appropriate and no adjustment is required. The second acceleration a2 phase occurs, which indicates that the second acceleration a2 is large, and the second acceleration needs to be reduced. The magnitude of the second acceleration drop takes full consideration of the optimized pre-cooling water level. The final rolling temperature is influenced by overlarge reduction, the rolling speed is influenced, the rolling temperature at the tail part of the strip steel is low, and the rolling stability is influenced; the cooling effect cannot be achieved due to too small drop, and the problem cannot be solved.
The second acceleration adjustment principle of the present embodiment is to maintain the amount of inter-stand cooling water between the original maximum value and the average value on the premise that the finish rolling temperature is within the range before improvement. And the second acceleration adjustment is determined according to an averaging method, the small acceleration and the large acceleration are averaged, the original first acceleration is taken as the first small acceleration, the second acceleration is taken as the large acceleration, and if the test result meets the condition of the finish rolling temperature and the cooling water amount is between the original maximum value and the average value, the second acceleration a2 can be determined (the original first acceleration is not changed). Otherwise, further adjustment is needed, when the cooling water amount is smaller than the original average value, the second acceleration is smaller and needs to be increased, the increased target value is the average value of the calculated value and the original second acceleration, the calculated method is that the small acceleration is the calculated acceleration a2, and the large acceleration is kept unchanged. If the amount of cooling water is larger than the maximum value, it means that the second acceleration is too large and needs to be decreased, and the target value of the decrease is the average value of the calculated value and the original first acceleration. When the cooling water amount is lower than the average value, the calculated value is used for replacing the original small value to increase the acceleration, the calculated value is used for replacing the large value to decrease the acceleration, the superposition replacement and the perfection are continuously carried out, and finally the cooling water amount is ensured to be between the average value and the maximum value of the cooling water amount before improvement
The method specifically comprises the following steps:
(1) determining the type and thickness specification of a target product;
(2) inquiring the used cooling water amount of 10 to 50 steel coils with the same type and the same thickness which are produced before, taking the maximum of the cooling water amounts as the maximum cooling water amount Mmax, and simultaneously calculating the average cooling water amount Mave;
(3) inquiring the head finish rolling outlet temperature of 10 to 50 coils of steel coils with the same type and the same thickness produced before, taking the maximum value as the maximum finish rolling outlet temperature FDTmax, and taking the minimum value as the minimum finish rolling outlet temperature FDTmin; (ii) a
(4) Inquiring the first acceleration a1 and the second acceleration a2 of the previously produced steel coil with the same type and the same thickness;
(5) let x1= a1, x2= a 2;
(6) let x = (x1+ x 2)/2; assigning a value of x to a second acceleration a2, i.e. let a2= x, produced as the second acceleration; monitoring the head finish rolling outlet temperature FDTj and the cooling water quantity Mj of the steel coil in the production process;
(7) if FDTj > FDTmax, reducing the temperature of the intermediate billet, and if FDTj < FDTmin, increasing the temperature of the intermediate billet until FDTmin < FDTj < FDTmax is met;
(8) if Mj < Mave, let x1= a2, and return to step 6; if Mj > Mmax, let x2= a2, return to step 6; if Mmax > Mj > Mave; the production test is completed and the current value of a2 is determined as the second acceleration.
Taking a steel tapping mark DU5821A1 of a 1780 production line as an example, the thickness of the product is 2.5-2.99 mm; iron scales appear at the tail part of the strip steel after the heat preservation cover is optimized; the optimization is carried out according to the following steps:
1. before query optimization, the average value of the cooling water quantity between the coil frames of the normal steel 30 coil with the thickness specification of 2.5-2.99mm of DU5821A1 is 57t/h, and the maximum value is 134 t/h;
2. inquiring the maximum value of the FDT at the head of the 30 rolls to be 854 ℃ and the minimum value to be 837 ℃;
3. inquiring whether the corresponding volume 30 has a first acceleration of 0.02m/s2 and a second acceleration of 0.08m/s 2;
4. the test is carried out according to the first acceleration of 0.02m/s2 and the second acceleration of (0.02 + 0.08)/2, namely 0.05 m/s2, and the tracking head FDT is 842 ℃ and is between the normal maximum and minimum values;
5. the flow rate of cooling water between the racks is 145t/h, which is larger than the maximum value of the original cooling water;
6. adjusting the second acceleration again in this way, and carrying out the test according to the first acceleration of 0.02m/s2 and the second acceleration (0.02 + 0.05)/2, namely 0.035m/s2, wherein the maximum flow of water between the tracking frames is 68t/h and is between the original maximum flow and the average value;
7. a first acceleration of 0.02m/s2 and a second acceleration of 0.035m/s2 are determined.
After the optimization is finished, the steel tapping mark DU5821A1 controls the appearance of iron scale at the tail part in the thickness of 2.5-2.99 mm.
Taking a steel tapping mark DU5821A1 of a 1780 production line as an example, the thickness of the product is 2.1-2.49 mm; iron scales appear at the tail part of the optimized strip steel of the heat-preserving cover; the optimization is carried out according to the following steps:
1. before optimization, the average value of the cooling water quantity between the maximum racks of a normal steel 30 coil with the thickness specification of 2.1-2.49mm of DU5821A1 is inquired, is 30t/h, and the maximum value is 105 t/h;
2. the maximum value of the FDT at the head of the 30 coils of the steel coil is 848 ℃, and the minimum value is 830 ℃.
3. Inquiring the first acceleration of the 30 coils of steel coils to be 0.02m/s2 and the second acceleration to be 0.1m/s 2;
4. performing tests according to the first acceleration of 0.02m/s2 and the second acceleration of (0.02 + 0.1)/2, namely 0.06m/s2, wherein the tracking head FDT is 840 ℃, and is between the normal maximum value and the normal minimum value, and the inter-frame cooling water amount is 98t/h and is between the maximum value and the average value;
5. the first acceleration of 0.02m/s2, the second acceleration of 0.06m/s2,
after the optimization is finished, the steel tapping mark DU5821A1 controls the appearance of iron scale at the tail part in the thickness of 2.1-2.49 mm.
Taking a steel tapping mark DU5821A1 of a 1780 production line as an example, the thickness of the product is 1.8-2.09 mm; iron scales appear at the tail part of the optimized strip steel of the heat-preserving cover; the optimization is carried out according to the following steps:
1. before optimization, the average value of the cooling water amount between the DU5821A1 coil frames with the normal thickness specification of 1.8-2.01mm and the maximum value of 85t/h is inquired;
2. inquiring the maximum value of the FDT at the head part of the 30 coils of the steel coil at 841 ℃ and the minimum value at 828 DEG C
3. Inquiring corresponding 30 volumes of first acceleration 0.02m/s2 and second acceleration 0.12m/s 2;
4. performing tests according to the first acceleration of 0.02m/s2 and the second acceleration of (0.02 + 0.12)/2, namely 0.07m/s2, wherein the tracking head FDT is 832 ℃, and is between the normal maximum value and the normal minimum value, and the amount of cooling water between the racks is 36t/h and is smaller than the average value;
5. performing tests according to the first acceleration of 0.02m/s2 and the second acceleration of (0.07 + 0.12)/2, namely 0.095m/s2, tracking the cooling water amount between the racks to be 55t/h, wherein the cooling water amount is between the average value and the maximum value;
6. a first acceleration of 0.02m/s2 and a second acceleration of 0.095m/s2 were determined.
After the optimization is finished, the steel tapping mark DU5821A1 controls the appearance of iron scale at the tail part in the thickness of 1.8-2.09 mm.
The present invention is not limited to the above-described embodiments. All technical solutions formed by equivalent substitutions fall within the protection scope of the claims of the present invention.
Claims (1)
1. A method for controlling the iron scale suitable for the temperature change of a hot-rolled intermediate billet is characterized by comprising the following steps:
(1) determining the type and thickness specification of a target product;
(2) inquiring the used cooling water amount of 10 to 50 steel coils with the same type and the same thickness which are produced before, taking the maximum of the cooling water amounts as the maximum cooling water amount Mmax, and simultaneously calculating the average cooling water amount Mave;
(3) inquiring the head finish rolling outlet temperature of 10 to 50 coils of steel coils with the same type and the same thickness produced before, taking the maximum value as the maximum finish rolling outlet temperature FDTmax, and taking the minimum value as the minimum finish rolling outlet temperature FDTmin;
(4) inquiring the first acceleration a1 and the second acceleration a2 of the steel coils of the same type and the same thickness produced before;
(5) let x1= a1, x2= a 2;
(6) let x = (x1+ x 2)/2; assigning a value of x to a second acceleration a2, i.e. let a2= x, produced as the second acceleration; monitoring the head finish rolling outlet temperature FDTj and the cooling water quantity Mj of the steel coil in the production process;
(7) if FDTj > FDTmax, reducing the temperature of the intermediate billet, and if FDTj < FDTmin, increasing the temperature of the intermediate billet until FDTmin < FDTj < FDTmax is met;
(8) if Mj < Mave, let x1= a2, and return to step 6; if Mj > Mmax, let x2= a2, and return to step 6; if Mmax > Mj > Mave, the production test is completed, and the current value of a2 is determined as the second acceleration.
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| JPH0773735B2 (en) * | 1987-06-24 | 1995-08-09 | 株式会社日立製作所 | Finishing temperature controller |
| FR2723012A1 (en) * | 1994-08-01 | 1996-02-02 | Mannesmann Ag | METHOD FOR CONTROLLING THE TEMPERATURE WHEN LAMINATING A HOT STRIP |
| JPH08252624A (en) * | 1995-03-16 | 1996-10-01 | Nkk Corp | Method for controlling finishing temperature in continuous hot rolling |
| JP3552646B2 (en) * | 2000-06-09 | 2004-08-11 | Ｊｆｅスチール株式会社 | Temperature control method for hot-rolled steel strip |
| JP4042667B2 (en) * | 2003-09-22 | 2008-02-06 | Ｊｆｅスチール株式会社 | Steel plate cooling method |
| CN100493750C (en) * | 2006-05-30 | 2009-06-03 | 宝山钢铁股份有限公司 | Method for ensuring the uniform temperature of the full-length of the hot fine rolling band steel |
| CN102781598B (en) * | 2010-03-11 | 2015-09-23 | 新日铁住金株式会社 | The manufacture method of hot rolled steel plate and manufacturing installation |
| CN102688900B (en) * | 2011-03-23 | 2014-08-20 | 宝山钢铁股份有限公司 | Method for guaranteeing hot continuous rolling mill finish rolling outlet temperature |
| CN103170506B (en) * | 2011-12-20 | 2015-04-22 | 上海梅山钢铁股份有限公司 | Hot rolling and finish rolling multi-level threading speed control method |
| CN102527739B (en) * | 2011-12-29 | 2014-01-22 | 中冶南方（武汉）自动化有限公司 | Time-optimization based automatic speed control equipment and method of reversible hot mill |
| CN103894425B (en) * | 2013-12-30 | 2016-06-29 | 北京首钢股份有限公司 | The control method of finishing temperature and device |
| CN104841701B (en) * | 2014-02-14 | 2017-01-04 | 宝山钢铁股份有限公司 | Method for controlling sheet coiling temperature during large-deceleration rolling of hot-rolled strip steel |
| CN106925614B (en) * | 2017-03-29 | 2018-12-14 | 首钢京唐钢铁联合有限责任公司 | A kind of hot-strip finishing temperature control method adjusted based on speed |
| CN107282650B (en) * | 2017-06-30 | 2018-12-04 | 北京首钢自动化信息技术有限公司 | A kind of high acceleration control method guaranteeing finishing temperature |
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