Background
Continuous casting is an important part in steel production, and the main process is that high-temperature molten steel is forced-cooled in a cooling area of a crystallizer to form a blank shell with a certain thickness, and a casting blank coming out of the cooling area of the crystallizer enters a secondary cooling area and is continuously cooled and cooled under the forced cooling of spray water until the molten steel in the casting blank is completely solidified. In the cooling process of the casting blank, the schematic drawing of continuous casting cooling is shown in FIG. 2, and the heat conduction of the casting blank and a clamping roller takes away about 15 percent of the total heat; the total heat of the casting blank surface is taken away by radiation heat transfer of about 25%; about 40% of the total heat is taken away by cooling the spray water; about 20% of the total heat is taken away by the evaporation of the cooling water, and it can be seen that about 60% of the total heat is taken away by the cooling water in different ways, so that the amount of sprayed water has a decisive effect on solidification and finally influences the quality of the casting blank.
At present, a lot of continuous casting spray water amount control methods are available, such as a pulling speed-water amount ratio control method, a pulling speed-water amount ratio control method based on effective pulling speed, a target surface temperature method based on-site measured temperature feedback, and a target surface temperature method based on calculated temperature feedback.
Among the above methods, the target surface temperature method based on the calculated temperature feedback is currently the most widely used method. The method generally sets the temperature of the outlet of the cooling area as a target temperature, and performs secondary cooling water control in order to calculate the temperature of a casting blank at the outlet of the cooling area to reach the target temperature in the casting process. There is also a method in which the average value of the surface temperature of the cast slab added to the entire cooling zone is used as a control factor. However, the above methods have a problem that the surface temperature is not effectively controlled after the casting blank enters the next cooling zone, and if the temperature is too high, the requirement of metallurgical criterion on the temperature return of the casting blank is violated, thereby causing quality defects.
Disclosure of Invention
In view of the above, the present invention provides a method for controlling secondary cooling water in continuous casting, which can minimize the sum of the variances between the surface temperature of a casting slab and a target surface temperature by controlling secondary cooling water without increasing the cost, thereby effectively improving the quality of the casting slab.
In order to achieve the purpose, the invention provides the following technical scheme:
a continuous casting secondary cooling water control method comprises the following steps: s1, recording the surface temperature and secondary cooling water amount of the casting blank in at least two adjacent control periods; and S2, performing feedback control on the secondary cooling water quantity through the statistical change of the surface temperature of the casting blank.
Optionally, the surface temperature of the casting blank in step S1 is acquired by a measurement method or calculated by a numerical simulation method.
Optionally, step S1 includes: calculating to obtain the target surface temperature of the corresponding node position of the casting blank
And the current actual temperature
Where i is a positive integer starting from 0 and ending with k
Optionally, step S2 includes: s2.1 calculating the variance sum S of the surface temperature of the casting blank and the target surface temperature of at least two adjacent control cycles
n-2、s
n-1(ii) a And deviation of secondary cooling water amount of nearly two cycles
S2.2 if S
n-2>s
n-1Then
Go to step S1; if s
n-2≤s
n-1Then Q is
n=Q
n-1。:
Alternatively, sn-2、sn-1The calculation formula of (2) is as follows:
the continuous casting secondary cooling water control device comprises a clamping roller for clamping a casting blank, a nozzle arranged on one side of the casting blank, a flowmeter for counting and controlling the water quantity of the nozzle, a temperature sensor for generating a water quantity signal and measuring the temperature of the casting blank and a temperature signal.
Optionally, the system further comprises a memory, a calculator and a controller which are electrically connected; recording the water quantity signal into a memory according to a generation time sequence; the temperature signals are recorded into a memory according to a generated time sequence and are transmitted to a calculator, and the sum of the variances of the surface temperature of the casting blank and the target surface temperature of at least two adjacent control periods is calculated through the temperature signals with the time sequence water quantity signal machine; and then the calculation result and the water quantity signal are transmitted to a controller, and the controller performs feedback regulation on the water quantity of the nozzle after performing logic judgment.
The invention has the beneficial effects that:
the invention can minimize the variance sum of the surface temperature of the casting blank and the target surface temperature by controlling the secondary cooling water quantity, thereby achieving the purpose of controlling the return temperature of the surface temperature of the casting blank and the outlet temperature of the cooling area within a reasonable range and effectively improving the quality of the casting blank.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Referring to fig. 1-4, the reference numbers in the figures refer to the following elements: a nip roller 1 and a nozzle 2.
The invention is suitable for all slab casting machines, and relates to a continuous casting secondary cooling water control device, which comprises a clamping roller 1 for clamping a casting blank, a nozzle 2 arranged on one side of the casting blank, a flowmeter for counting and controlling the water quantity of the nozzle 2, a temperature sensor for generating a water quantity signal and measuring the temperature of the casting blank, and a temperature signal.
Optionally, the system further comprises a memory, a calculator and a controller which are electrically connected; recording the water quantity signal into a memory according to a generation time sequence; the temperature signals are recorded into a memory according to a generated time sequence and are transmitted to a calculator, and the sum of the variances of the surface temperature of the casting blank and the target surface temperature of at least two adjacent control periods is calculated through the temperature signals with the time sequence water quantity signal machine; and then the calculation result and the water quantity signal are transmitted to a controller, and the controller carries out feedback regulation on the water quantity of the nozzle 2 after carrying out logic judgment.
The invention relates to a continuous casting secondary cooling water control method, which comprises the following steps: recording the surface temperature and secondary cooling water amount of the casting blank in nearly two control periods;
s1 method for calculating surface temperature of casting blank and target surface temperature in near two cycles according to the recorded dataThe difference sum is s
n-2And s
n-1And deviation of secondary cooling water amount of nearly two cycles
S2 if S
n-2>s
n-1Then
Go to step S1; if s
n-2≤s
n-1Then Q is
n=Q
n-1;
According to the invention, the difference sum of the surface temperature of the casting blank and the target surface temperature is minimized by controlling the secondary cooling water, so that the purposes of controlling the return temperature of the surface temperature of the casting blank and the outlet temperature of the cooling area within a reasonable range are achieved, and the quality of the casting blank is effectively improved.
The following is illustrated by specific examples:
in this embodiment, the implementation steps on each secondary cooling zone are the same, and therefore, only the secondary cooling 3 zone is selected for detailed description, which is specifically as follows:
1) recording the casting blank surface node temperature (shown as a graph pinch roll 4) and the secondary cooling water amount of nearly two control periods, as shown in a table 1;
TABLE 1 procedure record Table
2) Calculating the variance sum s of the calculated surface temperature of the casting blank and the target surface temperature in nearly two cycles according to the recorded data
n-2/s
n-1And deviation of secondary cooling water amount of nearly two cycles
The results data are shown in table 2;
sn-2=(998-998)2+(997-1015)2+(996-1010)2+(995-1006)2+(994-1003)2+(993-1000)2+(992-997)2+(991-995)2+(990-993)2
sn-1=(998-998)2+(997-1012)2+(996-1007)2+(995-1003)2+(994-1000)2+(993-997)2+(992-994)2+(991-992)2+(990-990)2
TABLE 2 calculation results
3) Due to s in step 2)n-2>sn-1Therefore, the set water amount Q of the next stepn265+8 273l/min, then go to step 1) until sn-2≤sn-1The water amount was kept constant.
The casting blank occasionally has transverse cracks in the original production process, and the transverse crack defect on the surface of the casting blank is greatly improved after the algorithm is applied.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.