CN117548639A - Process monitoring method for thick plate blank continuous casting production - Google Patents
Process monitoring method for thick plate blank continuous casting production Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 125
- 238000009749 continuous casting Methods 0.000 title claims abstract description 116
- 230000008569 process Effects 0.000 title claims abstract description 86
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 67
- 238000012544 monitoring process Methods 0.000 title claims abstract description 46
- 238000001816 cooling Methods 0.000 claims abstract description 139
- 238000005266 casting Methods 0.000 claims abstract description 101
- 238000007711 solidification Methods 0.000 claims abstract description 42
- 230000008023 solidification Effects 0.000 claims abstract description 42
- 238000012800 visualization Methods 0.000 claims abstract description 34
- 238000004364 calculation method Methods 0.000 claims abstract description 29
- 230000002159 abnormal effect Effects 0.000 claims abstract description 19
- 239000000463 material Substances 0.000 claims abstract description 13
- 230000000007 visual effect Effects 0.000 claims abstract description 13
- 239000000498 cooling water Substances 0.000 claims description 36
- 238000005516 engineering process Methods 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 238000012546 transfer Methods 0.000 claims description 12
- 239000000443 aerosol Substances 0.000 claims description 11
- 239000012496 blank sample Substances 0.000 claims description 11
- 238000013523 data management Methods 0.000 claims description 11
- 235000011837 pasties Nutrition 0.000 claims description 9
- 238000007726 management method Methods 0.000 claims description 8
- 238000013178 mathematical model Methods 0.000 claims description 8
- 239000011159 matrix material Substances 0.000 claims description 8
- 230000005499 meniscus Effects 0.000 claims description 7
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- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000012937 correction Methods 0.000 claims description 4
- 238000005520 cutting process Methods 0.000 claims description 4
- 239000000523 sample Substances 0.000 claims description 4
- 239000002352 surface water Substances 0.000 claims description 3
- 230000005856 abnormality Effects 0.000 abstract description 4
- 238000009851 ferrous metallurgy Methods 0.000 abstract description 2
- 238000004088 simulation Methods 0.000 abstract description 2
- 238000000465 moulding Methods 0.000 abstract 1
- 229910000831 Steel Inorganic materials 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- 230000004907 flux Effects 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
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- 239000002737 fuel gas Substances 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000011265 semifinished product Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000007794 visualization technique Methods 0.000 description 1
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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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
- B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
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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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
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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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/418—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM]
- G05B19/41875—Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] characterised by quality surveillance of production
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Abstract
The invention belongs to the technical field of ferrous metallurgy production, and discloses a process monitoring method for continuous casting production of thick plate blanks. Aiming at the molding processing characteristics of thick slab continuous casting, the method comprises the following steps: calculating a temperature field in a continuous casting solidification process, extracting key temperature data, and drawing a visual cloud picture in a multi-view solidification process; two-phase region position calculation and visualization based on material solidification properties; monitoring continuous casting process parameters and alarming abnormality. The cooling process record and the position tracking of each casting blank are realized, the casting blank temperature field is calculated through the simulation of production process parameters, and the temperature field is visualized. Control lines are arranged on the quality related process parameters to identify abnormal process conditions and give alarm prompts to technicians. The invention solves the problem that the visualization of the solidification process, the monitoring of the technological parameters and the abnormal alarm cannot be met in the prior art, can calculate in real time according to the production technological parameters and visualize the temperature field of the solidification process, and assists technicians to monitor the production process.
Description
Technical Field
The invention relates to the technical field of ferrous metallurgy production, in particular to a process monitoring method for continuous casting production of thick plate blanks.
Background
In the field of foundation construction such as ocean engineering, ship manufacturing, bridge construction, pressure vessels and the like, the requirements for thick high-strength high-toughness steel plates are vigorous. In order to produce a sheet material having high strength and good impact toughness, it is necessary to use a semifinished product that is 4 to 10 times thicker than the finished product. Because continuous casting has the advantages of high production efficiency, high steel rolling yield, short heating time, low fuel gas consumption, short production period and the like, stable production of flawless thick slabs becomes the main direction of continuous casting technology development.
Due to the metallurgical characteristics of the continuous casting process, the quality of the continuous casting blank is directly affected by the change of a temperature field, when the temperature field is abnormally distributed, the defects of cracks, segregation, shrinkage porosity and the like are easily generated, and when serious, production accidents such as steel leakage and the like can be possibly generated. At present, monitoring of a temperature field in a continuous casting process mainly depends on the surface temperature of a measuring key point of a thermometer and empirical formula calculation, and as a measuring result is influenced by factors such as water vapor, iron scale, water film and the like, the measuring accuracy is difficult to ensure; in addition, the thermometer can only measure the surface temperature of the casting blank, and cannot accurately monitor the internal temperature field. The monitoring of the technological parameters in the production process depends on manual work, and automatic abnormality detection and alarm cannot be realized.
With the development of information technology in recent years, a digital visualization technology and an abnormality detection technology become important means for solving the difficult problem, and technical conditions are provided for monitoring the continuous casting production process. The existing technologies at present are as follows: the utility model provides a continuous casting three-dimensional temperature field visualization method supporting multiple blank types, application number 202210553033.3, which is characterized in that a three-dimensional model can be established according to the blank types, and temperature field visualization is performed through rendering according to temperature data; the method has the defects that the existing temperature field data is relied on, and the three-dimensional model is built and rendering occupies a large amount of calculation resources, so that the instantaneity of the model is affected.
Disclosure of Invention
In view of the above problems, the invention provides a process monitoring method for continuous casting production of thick plate billets, which is used for monitoring a solidification process and technological parameters in the continuous casting production process and aims to solve the problems that the existing continuous casting monitoring system cannot meet the visualization of the solidification process, the technological parameter monitoring and abnormal alarms.
In order to achieve the above purpose, the invention adopts the following technical scheme: a process monitoring method for thick plate blank continuous casting production is divided into a data acquisition and management stage, a continuous casting temperature field visualization stage and an operation technology data monitoring stage;
the data acquisition and management stage is realized by a continuous casting computer system and a continuous casting production data management platform; the continuous casting computer system collects and manages equipment record data and automatic collection data in the production process, the continuous casting production data management platform carries out multi-source data matching and alignment on the equipment record data and the automatic collection data, and carries out data conversion, data cleaning and data matching to obtain component-process data;
the continuous casting temperature field visualization stage comprises cooling zone division, casting blank cooling process calculation, cooling boundary condition correction, continuous casting temperature field solving and continuous casting temperature field visualization; the composition-process data are sequentially processed by each part of the continuous casting temperature field visualization stage to obtain a continuous casting process temperature field visualization result;
the operation technology data monitoring stage comprises a process parameter monitoring part and an alarm part, wherein a control line is set for the operation technology data processed in the data acquisition and management stage, the processed operation technology data is monitored in real time, the data exceeding the control line is judged, the casting blank is determined to be an abnormal casting blank or an alarm is triggered; for the casting blank triggering the alarm, technicians intervene to analyze faults by combining operation technology data with the visual result of the continuous casting temperature field.
The continuous casting production data management platform divides a casting flow into N samples along a blank pulling direction; when the volume of the casting blank passing through the outlet of the crystallizer reaches 1/N of the total volume of the sample, dividing the casting blank corresponding to the volume into a casting blank sample, carrying out multi-source data matching and alignment on each casting blank sample according to equipment record data and automatic acquisition data corresponding to a time stamp, obtaining each stage of component-process data of the casting blank sample through data conversion, data cleaning and data matching, storing the data, and carrying out material tracking on the casting blank sample according to the continuous casting drawing speed;
and collecting a group of drawing speed and cooling process parameter data at intervals of 5-10 s for the composition-process data for constructing the continuous casting integral solidification temperature field, so as to realize integral recording of continuous casting process parameters.
The cooling area is divided into a plurality of cooling areas;
the casting flow is divided into three cooling areas of a crystallizer, a secondary cooling area and an air cooling area; dividing the secondary cooling area into a plurality of cooling sections according to the number and positions of cooling water loops and conical aerosol nozzles capable of being controlled to open and close along the casting flow direction, and calculating the cooling water quantity of the cooling sections according to the condition of the loops; dividing the secondary cooling area into n cooling sections, wherein the closed part of the loop is an air cooling section, and the open part of the loop is a water cooling section; the cooling water quantity Q per unit time of each water cooling section is based on the number and the position of the opened conical aerosol nozzles n For 1/n of the cooling water quantity Q per unit time of the cooling zone, the two side surfaces and the upper and lower surfaces of each cooling section are respectively provided with x conical aerosol nozzles and y conical aerosol nozzles, so that the cooling water quantity Q per unit time of the side surface and the cooling water quantity Q per unit time of the upper and lower surfaces of each section 2 Respectively calculated by the following formulas;
the cooling process is calculated specifically as follows: dividing the casting blank sample into a plurality of calculation units along the direction of drawing the casting blank according to the required calculation precision; the cooling process of the computing unit comprises computing boundary cooling conditions and cooling time, wherein the cooling process depends on the duration of each cooling segment experienced by the computing unit in production and the cooling intensity of each cooling segment; determining a cooling segment where a computing unit is currently located according to the distance of a crystallizer meniscus and the withdrawal speed, wherein the cooling boundary condition is related to the continuous casting withdrawal speed v and the casting time t, and the following relation is satisfied:
wherein L is the distance from a certain position of the casting flow to the meniscus, and the unit is m; v (t) is a function of the continuous casting drawing speed with respect to time t, and the unit is m/min; t is t 1 The unit is min for the time required for the casting blank to reach the position; the whole continuous casting process is divided into a plurality of cooling sections L k The length position corresponding to k epsilon N+ and L belongs to the cooling zone L k The cooling condition of the calculation unit corresponds to the cooling condition of the cooling section.
The cooling boundary condition correction corrects the cooling boundary condition of the cold area section; the cooling water quantity of the lower surface of the casting blank in unit time is alpha times of the cooling water quantity of the upper surface of the casting blank in unit time, and alpha is a cooling water loss coefficient; corrected upper surface water flow density W of casting blank Upper part Density W of water flow with lower surface Lower part(s) The relationship between them is calculated by the following formula;
solving and visualizing the continuous casting temperature field, determining the thermophysical property of a material and the section size of a casting blank for a large-section thick slab with the thickness of more than 400mm, and determining and correcting a cooling boundary condition in the cooling process according to component-process data recorded by a data acquisition and management part; calculating a casting blank solidification temperature field by using a finite difference method according to the continuous casting solidification heat transfer mathematical model and the corrected solidification boundary conditions for each divided calculation unit; solving the obtained result into a temperature field numerical matrix, extracting required data from the temperature field numerical matrix according to a required visual angle, and drawing a temperature field cloud picture to realize temperature field visualization; and drawing the position and the shape of the solidification pasty region on a cross-section temperature field cloud chart according to the liquidus and solidus temperatures of the material.
The continuous casting temperature field solving link uses a self-learning module, a plurality of temperature measuring points are arranged on a production line, and continuous casting solidification heat transfer mathematical model parameters of different cooling sections are corrected according to temperature measuring data and calculation results; and arranging thermometers at the outlet of the crystallizer of the continuous casting machine, at the water cooling end of the last section of the secondary cooling zone, at the inlet of the first withdrawal and straightening machine and at the flame cutting position, and adjusting parameters of a continuous casting solidification heat transfer mathematical model.
Respectively constructing temperature field cross sections perpendicular to the drawing direction and along the drawing direction according to the visual angle required for visualization, and supporting the multi-angle visualization of the internal temperature field of the casting blank; and extracting required data from the calculated temperature field numerical matrix, drawing a temperature field cloud picture according to numerical points, and drawing a solidification pasty area on the section temperature field cloud picture in an unset stage.
The control lines are set as follows: setting control lines of +/-3% - +/-5% for the drawing speed, casting temperature and cooling water quantity of each cooling section in unit time respectively, and marking as abnormal casting blanks when abnormal fluctuation of the process parameters exceeds the control lines for more than 5-10 seconds; when the fluctuation of the pull speed exceeds the control line by 10%, an alarm is triggered, and an operator intervenes.
The invention has the beneficial effects that: the process monitoring method for continuous casting production of the thick plate billets, which is provided by the invention, is applied to continuous casting production of thick plate billets with large cross sections, the thick plate billets with the thickness of more than 400mm, can be dynamically added into a computer system of a casting machine and is parallel to the existing continuous casting production control system, the cooling process record and the position tracking of each casting billet are realized by collecting and managing production data generated by a secondary computer system of the casting machine, and the temperature field of the casting billets is calculated through the simulation of production process parameters and visualized. Control lines are arranged on the quality related process parameters to identify abnormal process conditions and give alarm prompts to technicians. The invention solves the problem that the visualization of the solidification process, the monitoring of the technological parameters and the abnormal alarm cannot be met in the prior art, can calculate in real time according to the production technological parameters and visualize the temperature field of the solidification process, and assists technicians to monitor the production process. The method has the advantages of less calculation resources and high calculation speed, and meets the requirement of real-time regulation and control of online production.
Drawings
FIG. 1 is a flow chart of a process monitoring method for continuous casting production of thick slabs;
FIG. 2 is a flow chart of a continuous casting temperature field solution and continuous casting temperature field visualization;
FIG. 3 is a view showing a visual view of a continuous casting temperature field in a direction of drawing a continuous casting slab in example 1 of the present invention;
fig. 4 is a view showing a visual view of a continuous casting temperature field perpendicular to a continuous casting drawing direction in example 1 of the present invention.
Detailed Description
The process monitoring method for continuous casting production of the thick plate blank is used for realizing visualization and abnormal monitoring of the solidification process of continuous casting production, can detect production parameters in real time and visualize the internal temperature field and solidification condition of the thick plate blank, and assists production technicians to monitor abnormal conditions of the continuous casting process.
In order that the above-described aspects may be better understood, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
A process monitoring method for continuous casting production of thick plate blanks aims at large-section thick plate blanks with the thickness exceeding 400mm, and comprises a temperature field calculation part, a continuous casting process visualization part and a process parameter monitoring and alarming part. The visual monitoring system consisting of the temperature field calculation part and the continuous casting process visualization part and the numerical monitoring system consisting of the process parameter monitoring and alarm part together form the process monitoring system of the whole continuous casting process, and the data from the same source are processed differently to complete the respective functions.
The temperature field calculation part data is derived from a secondary control system, data management is carried out through a continuous casting production data management platform, multi-source data matching and alignment are realized, and the accurate division of a cooling area and the accurate recording of a casting blank cooling process are realized by combining a casting machine structure; and the process parameter monitoring and alarming part is used for monitoring real-time industrial data collected in the secondary control system, determining a casting blank to which the data belong by communicating with the continuous casting production data management platform, and setting a control limit on the data subjected to filtering treatment to judge whether the casting blank is required to be marked as an abnormal casting blank or trigger an alarm.
The continuous casting production data management platform collects and manages data generated in the continuous casting production process, and realizes multi-source data matching and alignment. Dividing a casting flow into N samples along the direction of drawing a casting blank, dividing a casting blank corresponding to the sample volume into a casting blank sample when the casting blank volume (1/N) passing through the outlet of a crystallizer reaches the sample volume, realizing the cooling process record and the position tracking of each casting blank, and constructing a solidification temperature field of any casting blank and marking the abnormality of the casting blank; and collecting a group of data of the pulling speed and the cooling strength of each cooling section at intervals of 5-10 s, so as to realize integral recording of continuous casting process parameters and construct a continuous casting integral solidification temperature field.
The process monitoring range covers the links from the crystallizer to the flame cutting, the monitoring process is not limited by production conditions, and any pulling speed and cooling strength are supported. And solving the solidification temperature field of the thick plate blank by using an unsteady state heat transfer partial differential equation according to the thermophysical properties, specific section size and cooling process of the material for producing the steel blank. The temperature field calculation section includes:
(1) Cooling zone division
(2) Calculation of casting blank cooling process
The division of the cooling zones is not limited to the structure of the continuous casting machine, but is subdivided according to a controllable cooling mechanism, in particular, for each cooling zone of the secondary cooling zones, opening according to the direction of withdrawalThe number and position of the conical aerosol nozzles dividing the cooling zone into n segments, the amount of cooling water per unit time (Q n In L/min) is 1/n of the cooling water amount (Q, in L/min) per unit time of the cooling zone, and each cooling section has x and y conical aerosol nozzles on its two side surfaces and upper and lower surfaces, respectively, so that the side surface (Q 1 In L/min) and upper and lower surfaces (Q) 2 The cooling water amount per unit time in L/min) is calculated by the following formula, respectively.
And correcting the boundary condition of the casting blank in the secondary cooling area. The cooling water quantity of the lower surface of the casting blank in unit time is alpha times of the cooling water quantity of the upper surface in unit time, and alpha is the cooling water loss coefficient. Corrected upper surface water flow density (W) Upper part ，L/(m 2 S) and the lower surface current density (W) Lower part(s) ，L/(m 2 S) may be calculated by the following formula.
Determining a cooling area and a cooling process of a casting blank at present according to the distance from a meniscus of a crystallizer and the blank drawing speed, wherein a cooling boundary condition is related to the continuous casting drawing speed v and the casting time t, and the following relation is satisfied:
wherein L is the distance from a certain position of the casting flow to the meniscus, and the unit is m; v (t) is a function of the continuous casting drawing speed with respect to time t, and the unit is m/min; t is t 1 Required for the casting blank to reach the placeIn minutes. The whole continuous casting process is divided into a plurality of cooling sections L k K represents N+ if the length position corresponding to L is in the cooling zone L k The cooling conditions of the cast slab unit correspond to the cooling conditions of the cooling section.
The visualization part of the continuous casting process is supported at a plurality of angles, and is used for visualizing the whole temperature field of the continuous casting process and the temperature evolution process of a certain steel block, and particularly, the position and the shape of a solidification pasty area can be drawn on a cross section temperature field cloud picture according to the liquidus and solidus temperatures of materials.
According to the visual angle of the needed visualization, temperature field cross sections perpendicular to the direction of drawing the blank and along the direction of drawing the blank can be respectively constructed so as to support the multi-angle visualization of the internal temperature field of the casting blank. And extracting required data from the calculated temperature field numerical matrix, drawing a temperature field cloud picture according to numerical points, and drawing a solidification pasty region on a section temperature field cloud picture in an unset stage, so that technicians can monitor the position and the shape of the casting blank pasty region in real time. In particular, the position of the solidification end in the casting flow can be observed visually.
The visualization process does not need to establish a three-dimensional model and render, so that the calculation resources are effectively saved, the calculation speed is improved, and the requirement of real-time regulation and control of online production is met.
The monitoring of the production process consists of a visualization part and a process parameter monitoring part, when abnormal cooling conditions occur, a cooling section with problems can be identified directly through a temperature field visualization interface, and a casting blank of the section is marked as an abnormal casting blank; control lines of +/-3% -5% are respectively arranged for technological parameters such as drawing speed, casting temperature, cooling water quantity in each sectional unit time and the like, and when abnormal fluctuation of the technological parameters exceeds the control lines for more than 5-10 seconds, abnormal casting blanks are marked. When the fluctuation of technological parameters, such as the pulling speed, possibly causing production accidents, such as continuous casting steel leakage, exceeds 10% of the control line, an alarm function is triggered to prompt the intervention of operators.
And arranging thermometers at the outlet of the crystallizer of the continuous casting machine, at the water cooling end of the last section of the secondary cooling zone, at the inlet of the first withdrawal and straightening machine and at the flame cutting position, and adjusting parameters of the solidification model to ensure the calculation accuracy of the model.
Example 1
The invention discloses a process monitoring method flow for continuous casting production of thick plate billets, which is characterized in that as shown in fig. 1, data management is carried out on production data collected by a continuous casting machine computer system, drawing speed required by temperature field calculation and visualization and data of cooling intensity of each cooling section are extracted, and solving calculation and visualization processes are carried out. The method comprises the steps of detecting data which are collected by all sensors and are directly related to continuous casting quality in real time, setting an error range of +/-3% for drawing speed and casting temperature, setting an error range of +/-4.5% for process parameters such as cooling water quantity in each sectional unit time, recording process parameters exceeding an allowable error range for more than 6 seconds, marking the casting blank as an abnormal casting blank, and triggering an alarm function to prompt intervention of operators when the fluctuation exceeds a control line by 10% for more than 5 seconds.
The flow chart of the visualization part of the temperature field calculation and continuous casting process, as shown in fig. 2, comprises four steps:
101. the thermophysical properties, dimensions and production process parameters of the material required to produce the steel blank are determined, and the solidification boundary conditions are determined from the process parameters.
102. And calculating a casting blank solidification temperature field by using a finite difference method according to the continuous casting solidification heat transfer mathematical model and the boundary conditions.
103. And extracting required data from the calculated temperature field numerical matrix according to the visual angle of the required visualization, and drawing a temperature field cloud picture according to the numerical points.
104. And drawing the position and the shape of the solidification pasty region on a cross-section temperature field cloud chart according to the liquidus and solidus temperatures of the material.
In the embodiment, Q235 carbon structural steel is taken as a concrete production steel grade, and thermodynamic calculation software is used for calculating thermophysical parameters such as Poisson's ratio, young modulus, heat conductivity coefficient, density, specific heat capacity and the like, as well as liquidus and solidus temperatures according to chemical components of the steel.
The section size of the continuous casting blank to be produced is 1600mm multiplied by 400mm, the continuous casting machine is an arc-shaped continuous casting machine, and the cooling section of the continuous casting machine is divided into a crystallizer, a foot roller area, a plurality of secondary cooling areas and an air cooling area.
The crystallizer heat transfer boundary conditions satisfy the following relationship:
wherein q is the heat flux density in kW/m in the crystallizer at a certain moment 2 The method comprises the steps of carrying out a first treatment on the surface of the a is the heat flux density of the meniscus of the crystallizer, and the unit is kW/m 2 ；q a The average heat flux density of the crystallizer is kW/m 2 ；L c The length of the crystallizer is m; v is the speed of the draw in m/min.
The boundary conditions of the heat transfer of the secondary cooling zone meet the following relationship:
h＝1.57×10 3 ×W 0.55 (1-T w ×0.0075)/k
wherein h is a heat exchange coefficient, and the unit is kW/(m) 2 C, a temperature; w is the flow density of cooling water, and the unit is L/(m) 2 ·s)；T w The unit is the temperature of cooling water; k is the adjustment coefficient.
The air cooling zone heat transfer boundary conditions satisfy the following relationship:
q＝ε 2 σ[(T b +273) 4 -(T a +273) 4 ]
wherein ε 2 The value of the radiation coefficient is 0.8; sigma is the stefin-boltzmann constant; t (T) b The unit is the surface temperature of a casting blank; t (T) a Is the ambient temperature in degrees celsius.
The continuous casting process is divided into a plurality of cooling segments according to a controllable cooling mechanism, and the cooling time of each cooling segment meets the following relation:
wherein L is i The length of the ith cooling section is m; a and b are respectively the starting time and the ending time of the casting blank entering the ith cooling section, and the unit is s; v (t) is a function of the continuous casting drawing speed with respect to time t in m/min.
Side surface (Q of each segment 1 ) And upper and lower surfaces (Q) 2 ) The cooling water amount per unit time of (2) is calculated by the following formula:
wherein n is the number of cooling segments of which the cooling area is divided; x and y are the number of conical aerosol nozzles on the two side surfaces and the upper and lower surfaces of each cooling segment, respectively; q is the cooling water quantity of the cooling area in unit time, and the unit is L/min.
The cooling water flow density calculation of the upper and lower surfaces of the slab is corrected by the following formula:
wherein alpha is a cooling water loss coefficient; w (W) Upper part And W is Lower part(s) The water flow density of the upper surface and the water flow density of the lower surface are respectively L/(m) 2 ·s)。
Based on a continuous casting solidification heat transfer mathematical model, a differential equation is replaced by a linear equation set to solve, in the embodiment, a finite difference method is used to divide a solving domain so as to discretize the equation, and then an interpolation method is adopted to obtain an approximate solution on the whole area of a fixed solution problem from the discrete solution.
The cooling conditions of the cast strand unit in the different cooling zones can be described by formulas, respectively.
The cooling boundary conditions of a cast strand in a mold section can be described by the following formula, wherein x and y are the width direction and thickness direction of the cast strand, respectively:
wherein T is the temperature in the unit of DEG C; λ is the coefficient of thermal conductivity, in W/(mK); q m (t) heat flux in W/m at unit time 2 。
The cooling boundary conditions of the slab in the secondary cooling zone can be described by the following formula:
wherein T is b The unit is the surface temperature of a casting blank; t (T) w The unit is the temperature of cooling water; h is the comprehensive heat exchange coefficient between the casting blank and the cooling water, and the unit is W/(m) 2 ·℃)。
The cooling boundary conditions of the cast slab in the air cooling section can be described by the following formula:
wherein epsilon is the emissivity; sigma is the stefin-boltzmann constant; t (T) b The unit is the surface temperature of a casting blank; t (T) a Is the ambient temperature in degrees celsius.
In the continuous casting production process, the solidification end point position and the shell thickness are required to be monitored on the whole casting flow, the calculated solidification temperature field data are extracted, a continuous casting blank temperature field section view along the blank drawing direction is drawn, as shown in fig. 3, and the position and the shape of a solidification pasty region are drawn on a cross section temperature field cloud picture according to the liquidus and solidus temperatures of the materials.
Further, if the temperature field of a specific cooling section is required to be observed in the production process, a cloud chart of the temperature field of the continuous casting blank can be drawn along the direction perpendicular to the continuous casting blank drawing direction, as shown in fig. 4.
Claims (8)
1. A process monitoring method for continuous casting production of thick plate blanks is characterized by comprising a data acquisition and management stage, a continuous casting temperature field visualization stage and an operation technology data monitoring stage;
the data acquisition and management stage is realized by a continuous casting computer system and a continuous casting production data management platform; the continuous casting computer system collects and manages equipment record data and automatic collection data in the production process, the continuous casting production data management platform carries out multi-source data matching and alignment on the equipment record data and the automatic collection data, and carries out data conversion, data cleaning and data matching to obtain component-process data;
the continuous casting temperature field visualization stage comprises cooling zone division, casting blank cooling process calculation, cooling boundary condition correction, continuous casting temperature field solving and continuous casting temperature field visualization; the composition-process data are sequentially processed by each part of the continuous casting temperature field visualization stage to obtain a continuous casting process temperature field visualization result;
the operation technology data monitoring stage comprises a process parameter monitoring part and an alarm part, wherein a control line is set for the operation technology data processed in the data acquisition and management stage, the processed operation technology data is monitored in real time, the data exceeding the control line is judged, the casting blank is determined to be an abnormal casting blank or an alarm is triggered; for the casting blank triggering the alarm, technicians intervene to analyze faults by combining operation technology data with the visual result of the continuous casting temperature field.
2. The process monitoring method for continuous slab casting production according to claim 1, wherein the continuous casting production data management platform divides the casting flow into N samples along the direction of slab drawing; when the volume of the casting blank passing through the outlet of the crystallizer reaches 1/N of the total volume of the sample, dividing the casting blank corresponding to the volume into a casting blank sample, carrying out multi-source data matching and alignment on each casting blank sample according to equipment record data and automatic acquisition data corresponding to a time stamp, obtaining each stage of component-process data of the casting blank sample through data conversion, data cleaning and data matching, storing the data, and carrying out material tracking on the casting blank sample according to the continuous casting drawing speed;
and collecting a group of drawing speed and cooling process parameter data at intervals of 5-10 s for the composition-process data for constructing the continuous casting integral solidification temperature field, so as to realize integral recording of continuous casting process parameters.
3. The process monitoring method for continuous slab casting production according to claim 1 or 2, wherein the cooling zone division is specifically;
the casting flow is divided into three cooling areas of a crystallizer, a secondary cooling area and an air cooling area; dividing the secondary cooling area into a plurality of cooling sections according to the number and positions of cooling water loops and conical aerosol nozzles capable of being controlled to open and close along the casting flow direction, and calculating the cooling water quantity of the cooling sections according to the condition of the loops; dividing the secondary cooling area into n cooling sections, wherein the closed part of the loop is an air cooling section, and the open part of the loop is a water cooling section; the cooling water quantity Q per unit time of each water cooling section is based on the number and the position of the opened conical aerosol nozzles n For 1/n of the cooling water quantity Q per unit time of the cooling zone, the two side surfaces and the upper and lower surfaces of each cooling section are respectively provided with x conical aerosol nozzles and y conical aerosol nozzles, so that the cooling water quantity Q per unit time of the side surface and the cooling water quantity Q per unit time of the upper and lower surfaces of each section 2 Respectively calculated by the following formulas;
the cooling process is calculated specifically as follows: dividing the casting blank sample into a plurality of calculation units along the direction of drawing the casting blank according to the required calculation precision; the cooling process of the computing unit comprises computing boundary cooling conditions and cooling time, wherein the cooling process depends on the duration of each cooling segment experienced by the computing unit in production and the cooling intensity of each cooling segment; determining a cooling segment where a computing unit is currently located according to the distance of a crystallizer meniscus and the withdrawal speed, wherein the cooling boundary condition is related to the continuous casting withdrawal speed v and the casting time t, and the following relation is satisfied:
wherein L is the distance from a certain position of the casting flow to the meniscus, and the unit is m; v (t) is a function of the continuous casting drawing speed with respect to time t, and the unit is m/min; t is t 1 The unit is min for the time required for the casting blank to reach the position; the whole continuous casting process is divided into a plurality of cooling sections L k The length position corresponding to k epsilon N+ and L belongs to the cooling zone L k The cooling condition of the calculation unit corresponds to the cooling condition of the cooling section.
4. The process monitoring method for continuous slab casting production according to claim 3, wherein the cooling boundary condition correction corrects a cooling boundary condition of a cold zone segment; the cooling water quantity of the lower surface of the casting blank in unit time is alpha times of the cooling water quantity of the upper surface of the casting blank in unit time, and alpha is a cooling water loss coefficient; corrected upper surface water flow density W of casting blank Upper part Density W of water flow with lower surface Lower part(s) The relationship between them is calculated by the following formula;
5. the process monitoring method for continuous casting production of thick slabs according to claim 1, wherein the continuous casting temperature field is solved and visualized, and after the thermophysical property of a material and the cross-sectional size of a casting blank are determined for a thick slab with a large cross-section with a thickness of more than 400mm, the cooling boundary condition in the cooling process is determined and corrected according to the component-process data recorded by the data acquisition and management part; calculating a casting blank solidification temperature field by using a finite difference method according to the continuous casting solidification heat transfer mathematical model and the corrected solidification boundary conditions for each divided calculation unit; solving the obtained result into a temperature field numerical matrix, extracting required data from the temperature field numerical matrix according to a required visual angle, and drawing a temperature field cloud picture to realize temperature field visualization; and drawing the position and the shape of the solidification pasty region on a cross-section temperature field cloud chart according to the liquidus and solidus temperatures of the material.
6. The process monitoring method for continuous casting production of thick plate billets according to claim 5, wherein the continuous casting temperature field solving step uses a self-learning module, a plurality of temperature measuring points are arranged on a production line, and continuous casting solidification heat transfer mathematical model parameters of different cooling sections are corrected according to temperature measuring data and calculation results; and arranging thermometers at the outlet of the crystallizer of the continuous casting machine, at the water cooling end of the last section of the secondary cooling zone, at the inlet of the first withdrawal and straightening machine and at the flame cutting position, and adjusting parameters of a continuous casting solidification heat transfer mathematical model.
7. The process monitoring method for continuous slab casting production according to claim 6, wherein temperature field cross sections perpendicular to the slab drawing direction and along the slab drawing direction are respectively constructed according to the required visual angle for supporting multi-angle visual casting blank internal temperature fields; and extracting required data from the calculated temperature field numerical matrix, drawing a temperature field cloud picture according to numerical points, and drawing a solidification pasty area on the section temperature field cloud picture in an unset stage.
8. The process monitoring method for continuous slab casting production according to claim 1, wherein the control line is set as follows: setting control lines of +/-3% - +/-5% for the drawing speed, casting temperature and cooling water quantity of each cooling section in unit time respectively, and marking as abnormal casting blanks when abnormal fluctuation of the process parameters exceeds the control lines for more than 5-10 seconds; when the fluctuation of the pull speed exceeds the control line by 10%, an alarm is triggered, and an operator intervenes.
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