CN114472548B - System and method for reducing head-tail temperature difference in ultra-long plate rolling process - Google Patents
System and method for reducing head-tail temperature difference in ultra-long plate rolling process Download PDFInfo
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- 238000005096 rolling process Methods 0.000 title claims abstract description 75
- 238000000034 method Methods 0.000 title claims abstract description 35
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 123
- 239000010959 steel Substances 0.000 claims abstract description 123
- 238000001816 cooling Methods 0.000 claims abstract description 83
- 230000001105 regulatory effect Effects 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 239000000498 cooling water Substances 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 description 12
- 238000005516 engineering process Methods 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000008520 organization Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000013072 incoming material Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Abstract
The invention discloses a system for reducing head-tail temperature difference in the rolling process of an ultra-long plate, which comprises the following components: the cooling device is provided with a plurality of rows of nozzles which are arranged along the length direction of the cooling device, and each row of nozzles is provided with a switch valve and a flow regulating valve; a shielding groove provided downstream of the cooling device along a traveling direction of the steel sheet and configured to be capable of traveling in a direction opposite to the traveling direction of the steel sheet so as to shield the nozzle; and the control device is respectively connected with the switch valve, the flow regulating valve and the shielding groove. Correspondingly, the invention also discloses a method for reducing the head-tail temperature difference in the ultra-long plate rolling process by using the system for reducing the head-tail temperature difference in the ultra-long plate rolling process.
Description
Technical Field
The invention relates to a system and a method for controlling temperature difference, in particular to a system and a method for reducing head-tail temperature difference in a steel plate rolling process.
Background
In order to further reduce the cost and improve the competitiveness, the capacity of newly built thick plate production lines is gradually increased in recent years, and the production lines are increased to more than 200 ten thousand tons from 100 to 150 ten thousand tons in early years. In order to improve the productivity of the thick plate production line, the specification of the blank is obviously changed, and long blank rolling becomes an important means for improving the productivity of the thick plate production line.
At the same time, the problems caused by long billet rolling are increasingly apparent, and the length of the finished plate manufactured by long billet rolling is prolonged, and is changed from the traditional length of less than 50m to the length of more than 60m, even 80-100m. Furthermore, it is possible to provide a device for the treatment of a disease. In the rolling process, after the head part of the steel plate enters the rolling mill, the tail part is still in an air cooling state, so that the air cooling time of the tail part is prolonged compared with that of the head part, and the increment delta t=L/v, wherein L is the length of the steel plate, and v is the rolling speed. The longer the steel plate length is, the larger the difference of the head and tail air cooling time of the steel plate is, and the larger the difference of the head and tail air cooling time is, so that the influence on the last several passes of rolling is obvious.
According to the air cooling radiation heat exchange formula Q=h sA(T∞-Ts), the air cooling temperature drop condition of the steel plates with different specifications can be calculated, wherein the radiation heat exchange coefficient is calculatedSigma is Stefan-Bolzman coefficient, T ∞ is known as ambient temperature, and T s is steel plate temperature. By sorting the calculation results, it can be found that: when the rolling speed of the steel plate with the length of 80m is 2.5m/s, the head-tail rolling temperature difference is 23-79 ℃, and the thinner the steel plate is, the larger the head-tail temperature difference is.
It should be noted that, the head-tail temperature difference of more than 30 ℃ is not allowed by the product technology, and the head-tail temperature difference of more than 30 ℃ can lead to uneven head-tail performance, mainly because of influencing the finishing temperature. The effect of the finishing temperature on the product texture properties is complex: the austenite recrystallization zone is rolled, grains with higher final rolling temperature are easy to recrystallize and grow, and the sizes of the head and tail grains are obviously different due to the overlarge head and tail temperature difference; rolling in an austenite non-recrystallization zone, wherein the number of deformation bands, dislocation and twin crystals formed by grain elongation is different due to different finishing temperatures; the high finishing temperature of the two-phase zone rolling results in an increase in the amount of ferrite precipitation, and an increase in the soft phase ratio results in a decrease in strength. Different steel grades are different, and the product performance is different by simply understanding different finishing temperatures. Therefore, the problem of head-to-tail temperature difference in the ultra-long plate rolling process is one of the bottlenecks of long billet rolling.
According to investigation, the existing temperature difference control means for head and tail rolling of the ultra-long plate is mainly controlled through speed-up rolling, and has the advantages of no need of newly added control equipment, limited speed-up range of a rolling mill and no obvious effect of improving the head and tail rolling temperature difference. In addition, the temperature drop of the steel plate is reduced by installing a heat preservation cover above the roller way, so that the temperature difference between the head and the tail is reduced.
For example: the Chinese patent literature with the publication number of CN106955896A and the publication date of 2017, 7 month and 18 days, named as an online water tank parameter adjusting system and method based on head-tail temperature difference of rolled pieces, discloses an online water tank parameter adjusting system and method based on head-tail temperature difference of bars, wherein the temperature of the bars after rolling is estimated by detecting the temperature of the bars before rolling and the temperature of the bars after rolling is compared with the measured temperature of the bars after rolling, so that a water tank water quantity control method is calculated.
Also for example: the Chinese patent literature with publication number CN102366763A and publication day 2012 3-7 entitled "a method for controlling rolling temperature of strip material" describes a method for controlling rolling temperature of strip material, which comprises measuring temperature at different positions along length direction of hot continuous rolling strip steel, comparing temperature difference to judge opening of valve, so as to control water flow at different positions, and realizing uniform rolling temperature.
For another example: chinese patent literature with publication number CN101905247a, publication day 12/8/2010 entitled "control method of head-tail temperature difference of semi-endless rolled ultra-long cast slab" discloses that the head-tail temperature difference of the slab is reduced by adding a soaking pit.
Based on the defects in the prior art, the invention expects to obtain the system and the method for reducing the head-tail temperature difference in the rolling process of the ultra-long plate, which can effectively solve the bottleneck problem of the thick plate long blank rolling technology, improve the head-tail temperature uniformity of the ultra-long plate, realize the uniform temperature rolling production of the ultra-long plate and ensure the uniform and consistent performance of the product in the length direction.
Disclosure of Invention
The invention aims to provide a system for reducing the temperature difference between the head and the tail in the rolling process of an ultra-long plate, which can effectively solve the bottleneck problem of the thick plate long billet rolling technology, improve the temperature uniformity of the head and the tail of the ultra-long plate, realize the uniform temperature rolling production of the ultra-long plate and ensure the uniform and consistent performance of the product in the length direction.
In order to achieve the above object, the present invention provides a system for reducing head-to-tail temperature difference in a super long plate rolling process, comprising:
The cooling device is provided with a plurality of rows of nozzles which are arranged along the length direction of the cooling device, and each row of nozzles is provided with a switch valve and a flow regulating valve;
a shielding groove provided downstream of the cooling device along a traveling direction of the steel sheet and configured to be capable of traveling in a direction opposite to the traveling direction of the steel sheet so as to shield the nozzle;
and the control device is respectively connected with the switch valve, the flow regulating valve and the shielding groove.
Further, in the system of the present invention, the method further includes:
the first thermometer is arranged at the inlet of the cooling device;
the second thermometer is arranged at the outlet of the cooling device;
The first temperature measuring instrument and the second temperature measuring instrument are respectively connected with the control device.
Further, in the system of the present invention, the system further comprises an upper computer connected with the control device, and the control device receives data information of the steel plate to be cooled from the upper computer.
Accordingly, another object of the present invention is to provide a method for reducing the head-to-tail temperature difference in the ultra-long plate rolling process based on the above system, which is implemented based on the above system.
In order to achieve the above object, the present invention provides a method for reducing the head-tail temperature difference in the process of rolling an ultra-long plate based on the system of the present invention, which comprises the steps of:
(1) When the steel plate head reaches the inlet of the cooling device, the control device controls the switch valve and the flow regulating valve to enable the cooling device to start cooling the steel plate head at the water flow density f;
(2) When the steel plate head advances to the outlet of the cooling device, the control device controls the shielding groove to start to walk at a speed V f along the direction opposite to the advancing direction of the steel plate until the shielding groove shields all nozzles of the cooling device.
Further, in the method of the present invention, the water flow density f is obtained based on the following formula:
Wherein c is the specific heat of a known steel plate, and the unit parameter is J/(kg ℃); m represents the known mass of the steel plate, and the unit of m is kg; delta T represents a temperature drop target of the head part of the steel plate, and the unit parameter of the delta T is the temperature; t Water and its preparation method is the known cooling water temperature, and the unit parameter is the temperature; t Head is the known initial temperature of the head of the steel plate, and the unit parameter is the temperature; t is cooling time, and the unit parameter is s; b is the surface area of a known steel plate, and the unit parameter is m 2; r is a known water pressure influence coefficient, and r is more than or equal to 1; f represents the water flow density to be obtained, and the unit parameter is L/(min.m 2); θ is a known heat exchange correction coefficient.
Further, in the method of the present invention, the cooling time t is obtained based on the following formula: t=s/v, where S represents the extension length of the cooling device and v represents the rolling speed.
Further, in the method of the present invention, the steel plate head temperature drop target Δt is obtained based on the steps of:
(1) A temperature drop curve database of steel plates with different thicknesses is established based on the following formula:
Wherein c is the specific heat of the known steel plate, and the unit parameter is J/(kg ℃); m is the known mass of the steel plate, and the unit parameter is kg; t Head is the known initial temperature of the head of the steel plate, and the unit parameter is the temperature; b is the known surface area of the steel plate, the unit parameter is m 2;T∞, the known ambient temperature and the unit parameter is the temperature; stefan-Bolzman constant σ= 5.768 × -8, unit parameter is J/(m 2s℃4); epsilon is a known blackness factor; t t represents the temperature of the length position of the steel plate at the time T.
(2) And searching the tail temperature T Tail of tail of the corresponding steel plate based on the temperature drop curve in the temperature drop curve database.
(3) The steel plate head temperature drop target Δt is obtained from Δt=t Head -T Tail of tail .
Further, in the method of the invention, the value range of the blackness coefficient epsilon is 0.6-0.9.
Further, in the method of the present invention, the velocity V f is obtained based on the following formula:
Wherein S is the extension length of the cooling device, L is the length of the steel plate, and V is the rolling speed.
Compared with the prior art, the system and the method for reducing the head-tail temperature difference in the ultra-long plate rolling process have the following advantages:
The system for reducing the head-tail temperature difference in the ultra-long plate rolling process can effectively solve the problem of overlarge head-tail temperature difference in the ultra-long steel plate production process, realizes uniform temperature rolling of the ultra-long steel plate, ensures uniform and consistent organization performance of the steel plate in the length direction, and has very important practical significance in improving the productivity of a thick plate production line and simultaneously ensuring the quality of products.
Drawings
Fig. 1 schematically shows a schematic structure of a system for reducing the head-tail temperature difference in the rolling process of ultra-long plates according to the present invention in an embodiment.
Fig. 2 schematically shows temperature drop curves for different gauge steel sheets.
Fig. 3 is a flowchart of a method for reducing the head-tail temperature difference in the ultra-long plate rolling process according to an embodiment of the present invention.
Detailed Description
The system and method for reducing the head-tail temperature difference in the ultra-long plate rolling process according to the present invention will be further explained and illustrated with reference to specific embodiments, however, the explanation and illustration do not unduly limit the technical scheme of the present invention.
Fig. 1 schematically shows a schematic structure of a system for reducing the head-tail temperature difference in the rolling process of ultra-long plates according to the present invention in an embodiment.
As shown in fig. 1, in this embodiment, the system for reducing the head-tail temperature difference in the ultra-long plate rolling process according to the present invention may include: a cooling device 1, a shielding tank 2 and a control device (not shown in the figures). The cooling device 1 has an extension length in the travelling direction of the steel plate 3, the cooling device 1 is provided with a plurality of rows of nozzles 11 which are arranged along the length direction of the cooling device, each row of nozzles 11 is provided with a switch valve and a flow regulating valve, and the switch and the flow can be independently controlled; the shielding groove 2 is provided downstream of the cooling device along the traveling direction of the steel sheet 3, and is capable of traveling in a direction opposite to the traveling direction of the steel sheet 3to shield the nozzle 11; the control device is respectively connected with the switch valve, the flow regulating valve and the shielding groove.
In addition, the system of the invention can also comprise: a first thermometer (not shown) and a second thermometer (not shown). The first temperature measuring instrument is arranged at the inlet of the cooling device, the second temperature measuring instrument is arranged at the outlet of the cooling device, and the first temperature measuring instrument and the second temperature measuring instrument can be respectively connected with the control device and used for detecting the temperature of the steel plate 3 so as to transmit the obtained temperature information of the steel plate 3 to the control device.
In addition, in some embodiments, the system according to the present invention may further include a host computer (not shown in the figure), and the host computer may be connected to a control device, where the control device may receive data information of the steel sheet 3 to be cooled from the host computer.
In the invention, the method for implementing the system for reducing the head-tail temperature difference in the ultra-long plate rolling process can comprise the following steps:
Step 1: when the head of the steel plate 3 reaches the inlet of the cooling device 1, the control device controls the on-off valve and the flow regulating valve to cause the cooling device 1 to start cooling the head of the steel plate 3 at the water flow density f.
Step 2: when the head of the steel plate 3 is advanced to the outlet of the cooling device 1, the control device controls the shielding groove 2 to start to advance at a speed V f in a direction opposite to the advancing direction of the steel plate 3 until the shielding groove 2 shields all the nozzles 11 of the cooling device 1.
It can be seen that in the system for reducing the head-to-tail temperature difference in the ultra-long plate rolling process according to the present invention, the nozzle in the cooling device is shielded by the shielding groove, so that the cooling water sprayed from the nozzle flows from both sides of the water tank to the drain. The reason why the shielding groove is used instead of the switching valve for closing the nozzle to control the number of groups sprayed at different positions of the steel plate 3 is that: the speed of the rolling process of the steel plate 3 is high, the response time of closing the valve of the nozzle 11 is low, and the requirement of rapidly adjusting the cooling time cannot be met.
Note that, for a steel sheet of a certain thickness, the head and tail air cooling time difference Δt=l/v of the steel sheet can be determined according to the rolling speed v and the steel sheet length L. Correspondingly, the air cooling time difference between the positions with different lengths and the head is determined by the distance Lx between the positions and the head and the rolling speed v: Δt x =lx/v.
As can be seen from the heat formula q=c×m× (T Head -Tt), the steel plate temperature T t at time T is:
Tt＝T Head -Q/(c×m) (1)
Wherein c represents the specific heat of the steel plate, and the unit parameter is J/(kg ℃); m is the known mass of the steel plate, and the unit parameter is kg; t Head is the known initial temperature of the steel plate head, and the unit parameter is the temperature.
Correspondingly, the main heat dissipation mode of the steel plate air cooling is radiation heat exchange, and the heat released by the steel plate in the t time is as follows:
Q＝t×hsB(T∞-T Head ) (2)
In the above formula, h s represents a radiation heat exchange coefficient, a unit parameter is J/(m 2. S. Cndot.) C, B represents a known surface area of the steel plate, m 2,T∞ represents a known ambient temperature, and a unit parameter is ℃.
Thus, the radiant heat exchange coefficient h s can be calculated from the following formula:
The temperature T t of the steel plate with the thickness at different moments can be calculated by the simultaneous combination of the formulas (1), (2) and (3), and the formula is as follows:
In the formula, the Stefan-Bolzman constant sigma= 5.768 × -8, and the unit parameter is J/(m 2s℃4); epsilon is a known blackness coefficient, and epsilon is generally between 0.6 and 0.9 in the air cooling state of the hot-rolled steel plate; t t represents the temperature of the length position of the steel plate at the time T.
The same calculation is carried out on the steel plates with different thicknesses, so that temperature drop curves of the steel plates with different specifications can be obtained, and a temperature drop curve database of the steel plates with different thicknesses is successfully built, as shown in fig. 2. The initial position of the temperature drop curve represents the head rolling temperature, and the temperatures of other points on the curve represent the rolling temperatures of the positions with different lengths of the steel plate. After the temperature drop curve database is established, the tail temperature T Tail of tail of the corresponding steel plate can be searched based on the temperature drop curve in the temperature drop curve database, so that the head temperature drop target Δt of the steel plate can be obtained according to Δt=t Head -T Tail of tail .
Fig. 3 shows a flowchart of an embodiment of the method for reducing the head-tail temperature difference in the rolling process of the ultra-long plate based on the system.
As shown in fig. 3, and referring to fig. 1 in combination, in the present embodiment, the method according to the present invention may calculate the water flow density f of the cooling device based on the steel plate head cooling time T and the steel plate head temperature drop target Δt.
In the embodiment, the method can confirm the steel types and specifications of the incoming materials according to the production information issued by the upper computer L3, inquire and determine the temperature difference in the length direction of the steel types from a database, and determine the cooling time of the head of the steel plate according to the rolling speed v and the extension length S of the cooling device: t=s/v.
After knowing the steel plate head temperature drop target Δt and the steel plate head cooling time T, the water flow density f can be calculated as follows:
Q＝c×m×ΔT＝(T Head -T Water and its preparation method )·t·B·h (5)
for spray cooling, the heat exchange coefficient h may be expressed as follows (other cooling methods may be expressed by corresponding empirical formulas):
By combining the above formula (5) and formula (6), the magnitude of the water flow density f can be obtained based on the following formula:
Wherein c is the specific heat of a known steel plate, and the unit parameter is J/(kg ℃); m represents the known mass of the steel plate, and the unit of m is kg; delta T represents a temperature drop target of the head part of the steel plate, and the unit parameter of the delta T is the temperature; t Water and its preparation method is the known cooling water temperature, and the unit parameter is the temperature; t Head is the known initial temperature of the head of the steel plate, and the unit parameter is the temperature; t is cooling time, and the unit parameter is s; b is the surface area of a known steel plate, and the unit parameter is m 2; r is a known water pressure influence coefficient, and r is more than or equal to 1; f represents the water flow density to be obtained, and the unit parameter is L/(min.m 2); θ is a known heat exchange correction coefficient.
In the method, after the water flow density f is obtained, the setting of cooling model parameters (v f and f) can be completed, a switch valve is opened, the opening of the valve is adjusted to enable the flow density to meet the set requirement and keep stable, and after the flow is stable, the head of the steel plate enters a cooling device to start cooling.
When the steel plate head reaches the inlet of the cooling device, the control device controls the switch valve and the flow regulating valve to enable the cooling device to start cooling the steel plate head at the water flow density f. When the steel plate head advances to the outlet of the cooling device, the control device controls the shielding groove to start to walk at a speed V f along the direction opposite to the advancing direction of the steel plate until the shielding groove shields all nozzles of the cooling device.
It should be noted that the velocity V f is obtained based on the following formula:
Wherein S is the extension length of the cooling device, L is the length of the steel plate, and V is the rolling speed.
The invention can solve the problem of overlarge temperature difference between the head and the tail in the production process of the overlong plate, realize the uniform temperature rolling of the overlong plate, ensure the uniform and consistent organization performance of the steel plate in the length direction, and ensure the product quality while improving the productivity of the thick plate production line.
In order to better illustrate the application of the system and the method for reducing the head-tail temperature difference in the ultra-long plate rolling process, the invention is provided with a specific embodiment for analysis for further illustration.
Examples
In the present embodiment, taking a Q235 steel grade with a thickness of 20mm as an example, when the rolling speed of a steel plate with a length of l=60 m is v=1.5 m/s, the air cooling time of the tail part of the steel plate is increased by Δt=60/1.5=40 s from the air cooling time of the head part, and the temperature difference Δt=57 ℃ between the head part and the tail part in the rolling process is known by inquiring a database.
The length s=5m of the cooling device before the rolling mill, and the cooling device has 10 groups of nozzles arranged along the length direction, the cooling time t=5/1.5=3.33S of the steel plate head.
The specific heat of the steel plate was set at 620J/(kg ℃ C.); setting the head temperature drop target delta T of the steel plate to 57 ℃; the water temperature is 30 ℃; the water pressure influence coefficient r=1; heat exchange correction coefficient θ=6.15; the cooling time of the steel plate head is controlled to be 3.33s, and the water flow density f=534 l/(min.m 2) is obtained by inputting a cooling model.
In the present embodiment, the shielding speed v f =5×1.5/(60-5) =0.136 m/s of the shielding groove. The on-off valve is opened, and the opening degree of the valve is adjusted to ensure that the flow density meets 534 l/(min.m 2) and keeps stable. The steel plate enters the cooling device at a rolling speed of 1.5m/s, when the head of the steel plate exits the cooling device, the shielding groove is started, and the shielding groove moves in the opposite direction to the running direction of the steel plate at a speed of 0.136m/s, so that the group-by-group shielding of the cooling nozzles is completed.
Finally, after the treatment of the system for reducing the head-tail temperature difference in the rolling process of the ultra-long plate, the temperature of the head of the steel plate measured by the second thermometer at the outlet of the cooling device is 926 ℃, the temperature of the tail of the steel plate is 913 ℃, and the head-tail temperature difference of the steel plate is 13 ℃.
From the above, the system for reducing the temperature difference between the head and the tail in the rolling process of the ultra-long plate can effectively solve the bottleneck problem of the thick plate long blank rolling technology, improve the temperature uniformity of the head and the tail of the ultra-long plate, and realize the uniform temperature rolling production of the ultra-long plate so as to ensure the uniform and consistent performance of the product in the length direction.
It should be noted that the combination of the technical features in the present invention is not limited to the combination described in the claims or the combination described in the specific embodiments, and all the technical features described in the present invention may be freely combined or combined in any manner unless contradiction occurs between them.
It should also be noted that the above-recited embodiments are merely specific examples of the present invention. It is apparent that the present invention is not limited to the above embodiments, and similar changes or modifications will be apparent to those skilled in the art from the present disclosure, and it is intended to be within the scope of the present invention.
Claims (4)
1. A method of reducing head-to-tail temperature differences during ultra-long plate rolling, based on a system for reducing head-to-tail temperature differences during ultra-long plate rolling, the system comprising:
The cooling device is provided with a plurality of rows of nozzles which are arranged along the length direction of the cooling device, and each row of nozzles is provided with a switch valve and a flow regulating valve;
a shielding groove provided downstream of the cooling device along a traveling direction of the steel sheet and configured to be capable of traveling in a direction opposite to the traveling direction of the steel sheet so as to shield the nozzle;
A control device connected with the switch valve, the flow regulating valve and the shielding groove respectively
The method comprises the steps of:
(1) When the steel plate head reaches the inlet of the cooling device, the control device controls the switch valve and the flow regulating valve to enable the cooling device to start cooling the steel plate head at the water flow density f;
(2) When the head of the steel plate advances to the outlet of the cooling device, the control device controls the shielding groove to start to walk at a speed V f along the direction opposite to the advancing direction of the steel plate until the shielding groove shields all nozzles of the cooling device;
wherein the water flow density f is obtained based on the following formula:
Wherein c is the specific heat of a known steel plate, and the unit parameter is J/(kg ℃); m represents the known mass of the steel plate, and the unit of m is kg; delta T represents a temperature drop target of the head part of the steel plate, and the unit parameter of the delta T is the temperature; t Water and its preparation method is the known cooling water temperature, and the unit parameter is the temperature; t Head is the known initial temperature of the head of the steel plate, and the unit parameter is the temperature; t is cooling time, and the unit parameter is s; b is the surface area of a known steel plate, and the unit parameter is m 2; r is a known water pressure influence coefficient, and r is more than or equal to 1; f represents the water flow density to be obtained, and the unit parameter is L/(min.m 2); θ is a known heat exchange correction coefficient;
The cooling time t is obtained based on the following formula: t=s/v, where S represents the extension length of the cooling device and v represents the rolling speed;
The steel plate head temperature drop target delta T is obtained based on the following steps:
(S1) establishing a temperature drop curve database of steel plates with different thicknesses based on the following formula:
wherein c is the specific heat of the known steel plate, and the unit parameter is J/(kg ℃); m is the known mass of the steel plate, and the unit parameter is kg; t Head is the known initial temperature of the head of the steel plate, and the unit parameter is the temperature; b is the known surface area of the steel plate, the unit parameter is m 2;T∞, the known ambient temperature and the unit parameter is the temperature; stefan-Bolzman constant σ= 5.768 × -8, unit parameter is J/(m 2s℃4); epsilon is a known blackness factor; t t represents the temperature of the length position of the steel plate at the moment T;
(S2) searching the tail temperature T Tail of tail of the corresponding steel plate based on a temperature drop curve in a temperature drop curve database;
(S3) obtaining a steel plate head temperature drop target Δt from Δt=t Head -T Tail of tail ;
The velocity V f is obtained based on the following formula:
Wherein S is the extension length of the cooling device, L is the length of the steel plate, and V is the rolling speed.
2. The method of claim 1, wherein the blackness factor epsilon has a value in the range of 0.6 to 0.9.
3. The method of claim 1, wherein the system further comprises:
the first thermometer is arranged at the inlet of the cooling device;
the second thermometer is arranged at the outlet of the cooling device;
The first temperature measuring instrument and the second temperature measuring instrument are respectively connected with the control device.
4. The method of claim 1, wherein the system further comprises a host computer connected to the control device, the control device receiving data information of the steel sheet to be cooled from the host computer.
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| CN202011147822.4A CN114472548B (en) | 2020-10-23 | System and method for reducing head-tail temperature difference in ultra-long plate rolling process |
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| CN202011147822.4A CN114472548B (en) | 2020-10-23 | System and method for reducing head-tail temperature difference in ultra-long plate rolling process |
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| EP0153688A1 (en) * | 1984-02-20 | 1985-09-04 | Nippon Steel Corporation | Method of cooling hot steel plates |
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