CN112191813A - Prediction method of bloom solidification end point - Google Patents

Prediction method of bloom solidification end point Download PDF

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Publication number
CN112191813A
CN112191813A CN202011092361.5A CN202011092361A CN112191813A CN 112191813 A CN112191813 A CN 112191813A CN 202011092361 A CN202011092361 A CN 202011092361A CN 112191813 A CN112191813 A CN 112191813A
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Prior art keywords
displacement
withdrawal
pressure
straightening machine
casting blank
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Inventor
李强
马建超
张康晖
王月
张玉飞
李解
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Jiangsu Shagang Group Co Ltd
Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Zhangjiagang Rongsheng Special Steel Co Ltd
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Jiangsu Shagang Group Co Ltd
Jiangsu Shagang Iron and Steel Research Institute Co Ltd
Zhangjiagang Rongsheng Special Steel Co Ltd
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Priority to CN202011092361.5A priority Critical patent/CN112191813A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1226—Accessories for subsequent treating or working cast stock in situ for straightening strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)

Abstract

The application discloses a method for predicting a bloom solidification end point, which comprises the steps of collecting signals in real time through a pressure sensor and a displacement sensor which are arranged on a withdrawal and straightening machine; processing the collected signals to generate a relation graph of unit displacement pressure and the position of the withdrawal and straightening machine; and then, judging the solidification final position of the casting blank by observing the trend of the line graph. According to the method and the device, the pressure and displacement change conditions can be monitored in real time, and the solidification end point position can be accurately judged according to the solidification rule. The method for predicting the solidification end point of the bloom is simple to operate, is easy to apply in actual production, and ensures the internal quality of a casting blank by matching with a soft reduction technology.

Description

Prediction method of bloom solidification end point
Technical Field
The invention belongs to the technical field of steel making, and relates to a method for predicting a solidification end point position of a bloom.
Background
The main internal defects of the continuous casting billet comprise center segregation, shrinkage cavity and looseness, and are difficult to eliminate in the subsequent heating and rolling processes, so that the product performance is influenced finally. When the continuous casting billet is solidified, solute enrichment occurs in the liquid phase of the two-phase region due to the selective separation and crystallization between the solid phase and the liquid phase. The solidification contraction generates negative pressure to make the molten steel with solute elements enriched between dendrites flow to form macro segregation. Meanwhile, the molten steel has poor fluidity in the later solidification stage, solidification shrinkage cannot be supplemented, and looseness and even shrinkage cavity can be caused.
The soft reduction technology is characterized in that a certain reduction is applied to a casting blank before the solidification end point, so that the volume of a liquid core of the casting blank is reduced, central porosity and shrinkage cavity generated by volume shrinkage in the solidification process are compensated, meanwhile, the phenomenon that molten steel flows due to the enrichment of interdendritic solutes is reduced or avoided, and the purpose of improving macrosegregation and porosity is achieved. Therefore, it is very important to accurately predict the solidification end point position of the continuous casting slab.
At present, the technology which is widely applied is to build a solidification model to predict the solidification end point of the continuous casting billet by utilizing physical property parameters of steel grades, pulling speed, crystallizer water flow, secondary cooling water distribution and the like. The method has more influencing factors, the reduction position is easy to deviate, and the center quality of the casting blank cannot meet the requirement.
Patent CN106345979A describes an apparatus and method for determining the position of the solidified end of a cast strand based on the detection of the load of guide rollers. A plurality of detection positions are arranged between the machine frames supporting the guide rollers, and a load cell and a displacement cell are respectively arranged on each detection position. The load cell and the displacement cell are respectively connected with the processing unit, and the processing unit compares the load change condition sent by each detection position to judge the position of the solidification tail end of the casting blank. The method is mainly suitable for a sector-section multi-roller slab continuous casting machine, the load change is not only related to the solidification state of the blank, but also related to the reduction amount, and the accuracy of judging the solidification end point position is low only by comparing the load change.
Disclosure of Invention
The invention aims to provide a method for predicting a solidification end point position of a bloom, so as to overcome the defects in the prior art.
In order to achieve the purpose, the invention provides the following technical scheme: a method for predicting the solidification end position of a bloom comprises the steps of collecting signals of a tension leveler pressure sensor and a displacement sensor in real time in the production process, and generating a relation graph of unit displacement pressure and the tension leveler position after processing. And judging the position of the solidification end point of the casting blank by observing the trend of the line graph. The method comprises the following specific steps:
(1) and the pressure sensors on the tension leveler feed back pressure values applied to the casting blank by each tension leveler, and the displacement sensors feed back displacement generated by each tension leveler to the casting blank.
(2) Definition of FiPressure value, S, applied to the casting blank for the withdrawal and straightening unitiFor the displacement generated by the withdrawal and straightening machine, the value of i is the corresponding withdrawal and straightening machine number, and 1, 2, … …, n-2, n-1, n and … … are taken (n is a positive integer).
(3) Defining the unit displacement pressure as deltai，δi＝Fi/￡iIn which F isiIs the pressure value applied to the casting blank by the withdrawal and straightening machineiAnd (3) taking the value i as the number of the corresponding withdrawal straightening machine for the actual displacement of the withdrawal straightening machine on the casting blank, and taking 1, 2, … …, n-2, n-1, n and … … (n is a positive integer).
(4) Generating a relation graph of unit displacement pressure and the position of the withdrawal and straightening unit at the main control interface of the continuous casting machine, if the relation graph meets (delta)n-1-δn-2) < 0, and (delta)n-δn-1) When the solidification point is more than 0, the solidification end point is positioned between No. n-2 and No. n-1 withdrawal and straightening machines.
Furthermore, the pressure sensor and the displacement sensor are connected with the supporting roll corresponding to the movable roll of the tension leveler, and when the tension leveler is in an idle state, the feedback values of the pressure sensor and the displacement sensor are both 0.
Further, the number 1 is in £ corresponding to the actual displacement of the casting blank1＝S1The number i of the withdrawal and straightening unit is £i＝Si-Si-1And the value of i is the number of the corresponding withdrawal and straightening machine, and 2, 3, … …, n-2, n-1, n and … … are taken (n is a positive integer).
According to the prediction method of the bloom solidification end point position, solidification latent heat is slowly released in the solidification process of high-carbon steel molten steel according to the solidification rule, and the shrinkage rate of a solidified billet shell is about 0.5-0.7 mu m/s; when the solidification end point is reached, the solidification latent heat and the sensible heat are released rapidly, the temperature of the casting blank is reduced greatly, and the shrinkage rate of a solidified blank shell is about 3.0-5.0 mu m/s. When the manual static displacement control model is adopted, the actual displacement of each tension leveler to the casting blank is a fixed value, because the shrinkage of the casting blank at the solidification end point position is large, only small pressure is needed for achieving the actual displacement of the tension leveler, the unit displacement pressure value corresponding to the tension leveler is small relative to the unit displacement pressure values corresponding to the front tension leveler and the rear tension leveler, so that the solidification end point position is accurately predicted,
compared with the prior art, the invention can monitor the change conditions of pressure and displacement in real time by acquiring the pressure sensor signal and the displacement sensor signal of each tension leveler in the production process in real time, and generate a position relation graph of unit displacement pressure and the tension leveler at a main control interface of a continuous casting machine; according to the solidification rule, the position of the solidification end point can be accurately judged; the method is simple to operate and easy to apply in actual production, and ensures the internal quality of the casting blank by matching with a soft reduction technology.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic installation diagram of a pressure sensor and a displacement sensor of a withdrawal and straightening unit of a method for predicting a solidification end point position of a bloom according to an embodiment of the present invention;
FIG. 2 is a graph showing the relationship between the unit displacement pressure and the withdrawal and straightening unit position in the method for predicting the solidification end point of a bloom in accordance with the embodiment of the present invention;
wherein: the device comprises a support 1, a support roll 2, a displacement sensor 3, a casting blank 4, a movable roll 5 and a pressure sensor 6.
Detailed Description
The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Examples
The cross section of the bloom continuous casting machine is 300mm multiplied by 400mm, and the equipment has 7 withdrawal and straightening machines in total, and 1#, 2#, 3#, 4#, 5#, 6# and 7# execute the function of casting blank reduction. And predicting the solidification end point of the steel type SWRH77B by using a method for predicting the solidification end point position of the continuous casting slab based on pressure and displacement feedback.
(1) According to the figure 1, the pressure sensor 3 and the tension sensor 6 are installed between the movable roller 5 and the supporting roller 2; the 1-7# withdrawal and straightening unit equipment is provided with a pressure sensor and a displacement sensor, and the pressure sensor and the displacement sensor collect signals and transmit numerical values;
(2) in the casting process, the drawing speed is 0.62m/min, secondary cooling water distribution is 0.20L/kg, and a dynamic soft reduction control model is selected;
(3) the pressure sensor collects the pressure value F of each tension leveleriThe specific numerical values are shown in Table 1;
TABLE 1 pressure value of each withdrawal and straightening machine in the production process
Figure BDA0002722567380000041
(4) The displacement sensor collects the displacement S of each tension leveleriThe specific numerical values are shown in Table 2;
TABLE 2 Displacement of each withdrawal and straightening unit in the production process
Figure BDA0002722567380000042
(5) Actual displacement of each withdrawal and straightening machine £i，￡i＝Si-Si-1And the value of i is the number of the corresponding withdrawal and straightening machine, and 2, 3, 4, 5, 6 and 7 are selected, wherein £1＝S1The specific numerical values are shown in Table 3;
TABLE 3 actual displacement of each withdrawal and straightening unit in the production process
Figure BDA0002722567380000043
(6) Pressure per unit displacement amount of deltai，δi＝Fi/￡iThe value i is the number of the corresponding withdrawal and straightening machine, 1, 2, 3, 4, 5, 6 and 7 are taken, and the specific numerical values are shown in a table 4;
TABLE 4 pressure of unit displacement of each withdrawal and straightening unit in production process
Figure BDA0002722567380000044
(7) The relationship between the generated unit displacement amount pressure and the position of the withdrawal and straightening unit is shown in FIG. 2, which is shown in FIG. 2 (delta)4-δ3) < 0, and (delta)5-δ4) And when the solidification point is more than 0, the solidification end point is positioned between No. 3 and No. 4 withdrawal and straightening machines.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing is merely a detailed description of the present application, and it should be noted that modifications and embellishments could be made by those skilled in the art without departing from the principle of the present application, and these should also be considered as the protection scope of the present application.

Claims (3)

1. A prediction method of a bloom solidification end point is characterized in that a pressure sensor and a displacement sensor which are arranged on a withdrawal and straightening machine are used: the method specifically comprises the following steps:
(1) recording the pressure value of the upper tension leveler of the pressure sensor to the casting blank as FiRecording the displacement quantity generated by the tension leveler on the displacement sensor as SiI is the number of the corresponding withdrawal and straightening machine;
(2) obtaining the actual displacement of the casting blank in the tension leveler according to the fact that the displacement generated by the tension leveler in the step (1) is Si; the actual displacement of the casting blank in the tension leveler meets the following requirements:
Figure FDA0002722567370000011
Figure FDA0002722567370000012
wherein:
Figure FDA0002722567370000013
for casting blanks in withdrawal and straightening machines numbered iActual amount of displacement, SiThe displacement of the withdrawal and straightening machine with the number i; si-1The displacement of the withdrawal and straightening machine with the serial number of i-1; i is a positive integer greater than or equal to 2;
(3) the pressure value of the upper withdrawal straightening machine in the steps (1) and (2) to the casting blank is FiAnd the actual displacement of the casting blank in the withdrawal and straightening unit
Figure FDA0002722567370000014
Obtaining unit displacement pressure, wherein the unit displacement pressure meets the following requirements:
Figure FDA0002722567370000015
wherein: deltai
The unit displacement pressure of the withdrawal and straightening machine numbered i;
Figure FDA0002722567370000016
the actual displacement of the casting blank in the tension leveler with the number i is taken as the reference value; fiThe pressure value of the withdrawal and straightening machine to the casting blank is set;
(4) and when the unit displacement pressure of the withdrawal and straightening machine meets the following requirements: (deltan-1-δn-2) < 0, and (delta)n-δn-1) When the solidification point is more than 0, the solidification end point of the bloom is positioned between the withdrawal and straightening machines with the numbers of n-2 and n-1;
wherein: deltan-1Is the unit displacement pressure of the withdrawal and straightening machine with the number of n-1; deltan-2Is the unit displacement pressure of the tension leveler with the number of n-2; deltanN-numbered unit displacement pressure of the withdrawal and straightening machine; n is the number of the withdrawal and straightening unit and n is a positive integer greater than or equal to 3.
2. The method of predicting the solidification end point of a bloom as set forth in claim 1, wherein: the pressure sensor displacement sensor is connected with a supporting roll corresponding to the movable roll of the withdrawal and straightening machine; when the tension leveler is in an idle state, the feedback values of the pressure sensor and the displacement sensor are both 0.
3. The method of predicting the solidification end point of a bloom as set forth in claim 1, wherein: the actual displacement of the casting blank in the tension leveler meets the following requirements:
Figure FDA0002722567370000017
wherein:
Figure FDA0002722567370000018
the actual displacement of the casting blank in the tension leveler with the number of 1 is taken as the reference value; s1The displacement of the withdrawal and straightening machine with the number of 1;
CN202011092361.5A 2020-10-13 2020-10-13 Prediction method of bloom solidification end point Pending CN112191813A (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993004802A1 (en) * 1991-09-12 1993-03-18 Giovanni Arvedi A process and apparatus for the manufacture of billets and blooms from a continuously last steel showing high or excellent quality
JPH08164460A (en) * 1994-12-14 1996-06-25 Sumitomo Metal Ind Ltd Production of continuously cast slab having good internal quality
DE19903928A1 (en) * 1998-11-06 2000-05-11 Schloemann Siemag Ag Production of continuously cast slabs comprises using a solidifying cord shell in a cord guide extending from the mold to the final solidification point
CN101704079A (en) * 2009-09-28 2010-05-12 田陆 Control method for casting of continuous-cast billet
CN102500747A (en) * 2011-11-15 2012-06-20 田志恒 Online detection system for solid-phase internal boundaries and solidification end positions of continuous casting blanks and method
CN203944811U (en) * 2014-06-17 2014-11-19 中冶连铸技术工程有限责任公司 Bloom continuous casting base solidification end position detecting device
CN111507035A (en) * 2020-04-17 2020-08-07 东北大学 Design method for traveling wave electromagnetic stirring at solidification tail end of continuous casting billet

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993004802A1 (en) * 1991-09-12 1993-03-18 Giovanni Arvedi A process and apparatus for the manufacture of billets and blooms from a continuously last steel showing high or excellent quality
JPH08164460A (en) * 1994-12-14 1996-06-25 Sumitomo Metal Ind Ltd Production of continuously cast slab having good internal quality
DE19903928A1 (en) * 1998-11-06 2000-05-11 Schloemann Siemag Ag Production of continuously cast slabs comprises using a solidifying cord shell in a cord guide extending from the mold to the final solidification point
CN101704079A (en) * 2009-09-28 2010-05-12 田陆 Control method for casting of continuous-cast billet
CN102500747A (en) * 2011-11-15 2012-06-20 田志恒 Online detection system for solid-phase internal boundaries and solidification end positions of continuous casting blanks and method
CN203944811U (en) * 2014-06-17 2014-11-19 中冶连铸技术工程有限责任公司 Bloom continuous casting base solidification end position detecting device
CN111507035A (en) * 2020-04-17 2020-08-07 东北大学 Design method for traveling wave electromagnetic stirring at solidification tail end of continuous casting billet

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
朱苗勇: "" 连铸大方坯凝固末端重压下技术及其应用"", 《"第十届中国钢铁年会"暨"第六届宝钢学术年会"论文集》 *

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Application publication date: 20210108