CN108446505A - Casting blank solidification Heat Transfer Calculation in a kind of funnel mould - Google Patents
Casting blank solidification Heat Transfer Calculation in a kind of funnel mould Download PDFInfo
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Abstract
Casting blank solidification Heat Transfer Calculation in a kind of funnel mould of present invention offer, is related to steel-making continuous casting technical field.This method consults the physical parameter for obtaining steel, copper coin and cooling water first, and establishes 1/4 casting blank crystallizer finite element model, and assigns its corresponding physical parameter；Then the interface heat transfer model of the distribution of coupling liquid slag blanket, the distribution of solid-state slag blanket and air gap distribution is resettled；Last set contact, contact relation；Load primary condition, boundary condition；Load Creep Equation；Defined analysis engineering, and submit calculate until copper coin hot-face temperature reaches stable state in parallel mode.Casting blank solidification Heat Transfer Calculation in funnel mould provided by the invention; can liquid covering slag, the DYNAMIC DISTRIBUTION of solid-state covering slag and air gap and the Temperature Distribution of copper plate of crystallizer and solidified shell, contact condition during accurate description funnel mould continuous casting sheet billet, heat/mechanical behavior in the sheet billets process of setting such as the contraction of strand and deformation.
Description
Technical field
The present invention relates to casting blank solidification Calculation of Heat Transfer sides in steel-making continuous casting technical field more particularly to a kind of funnel mould
Method.
Background technology
Continuous casting and rolling technique of sheet bar originates from the eighties in last century, is a kind of short route hot-strip production new technique.
As the core component of sheet blank continuous casting, funnel mould directly decides production efficiency and the production of thin slab continuous casting and rolling producing line
Product surface.System understands the solidification and heat transfer behavior of green shell in sheet blank continuous casting production process funnel mould, is to improve infundibular ganglion
The premise and basis of brilliant device structure and the new and effective funnel mould of exploitation.Due to process of setting of the steel in funnel mould
Has the characteristics that "black box", traditional Physical Experiment is relatively difficult to carry out comprehensive description to Heat transfer in crystallizer, currently, more
The Heat transfer in funnel mould is studied using method for numerical simulation.
In practical sheet billet production process, since the inner-cavity structure of funnel mould molten bath zone is complex, simultaneously
By green shell dynamic deformation effect of contraction, the behavior of the interface heat transfers such as flux film and air gap is substantially distinguished from traditional slab production,
Therefore the more traditional slab of solidification behavior of the green shell in funnel mould is increasingly complex, and numerical simulation difficulty is larger.
The paper of entitled " Modeling the thin-slab continuous-casting mold " is by establishing three
Finite element model is tieed up, the influence to green shell Heat transfer in crystallizer in casting process such as pulling rate, copper plate thickness is had studied.So
And the model does not consider that liquid in crystallizer, solid covering slag distribution, air gap are formed and the crystallizers keys such as extension heat transfer influence factor
Influence to strand heat transfer, therefore cannot really reflect the solidification and heat transfer Behavior law of strand in funnel mould.It is entitled
“Thermal and mechanical behavior of copper molds during thin-slab casting(I)：
Plant trial and mathematical modeling " and " Thermal and mechanical Behavior of
copper molds during thin-slab casting(II)：The paper studies of Mold crack formation " are followed
The stress and strain relationship of copper coin under ring load.The model does not consider copper coin-strand equally using copper plate of crystallizer as research object
Between contact condition, the behavior of flux film DYNAMIC DISTRIBUTION influence that copper plate temperature field is developed therefore equally cannot really reflect
The heat transfer of copper coin and deformational behavior.
Application No. is the patents of invention of CN201310355699.9, disclose a kind of based on slag film and air gap DYNAMIC DISTRIBUTION
Continuous cast mold heat flow density determines method, realize to strand-copper plate temperature in conventional plate blank casting process and contact condition,
The coupling analysis that slag film is shunk with air gap distribution, casting blank solidification；However the computational methods are based on two-dimensional finite element model, due to leakage
The funnel structure design that bucket crystallizer wide face from top to bottom continuously reduces, two dimensional model can not be to funnel structures that this continuously becomes smaller
Deformation and casting blank deformation are described, therefore are not suitable for describing the behaviors such as the casting blank solidification heat transfer in funnel mould；
Application No. is the patent of invention of CN201410652827.0, a kind of continuous crystallizer protecting slag liquid, solid is disclosed
The computational methods of state slag film and air gap thickness non-uniform Distribution are realized to covering slag and air gap in conventional plate blank continuous cast mold
The description of non-uniform thickness distribution；The invention is equally based on two dimensional model, thus can not equally be applied to description funnel mould
Interior casting blank solidification heat transfer；
Invention content
In view of the drawbacks of the prior art, casting blank solidification Heat Transfer Calculation in a kind of funnel mould of present invention offer, it is real
Now to the accurate description of green shell dynamic heat transfer behavior in sheet billet funnel mould.
Casting blank solidification Heat Transfer Calculation in a kind of funnel mould, includes the following steps：
Step 1 consults the physical parameter for obtaining steel according to the steel grades of simulation, while consulting and obtaining funnel mould institute
The thermal physical property parameter of the copper coin and cooling water that use, specifically includes：
According to the mass percentage of essential element in the steel grade of wanted simulation casting, the liquidus curve temperature for obtaining the steel is consulted
Degree, solidus temperature, latent heat of solidification and the steel grade in process of setting thermal coefficient, density, specific heat and coefficient of thermal expansion with
The variation of temperature；It consults and obtains steel elasticity modulus, Poisson's ratio and yield limit parameter at different temperatures and crystallizer copper
The thermal coefficient of plate and cooling water, specific heat and density physical parameter；
Step 2 establishes Three Dimensional Thermal/couple of force conjunction finite element model according to funnel mould-strand system, and specific method is：
Step 2.1 pours into a mould cross dimensions according to funnel mould copper coin structure chart and strand, establishes 1/2 wide face crystallizer
The 3-D geometric model of copper coin and 1/2 leptoprosopy crystallizer copper board combining structure；
Step 2.2, according to funnel mould width suitable for reading, narrow copper plate taper and crystallizer effective height, establish curved
The 3-D geometric model of 1/4 casting blank section at lunar surface, the height along throwing direction are crystallizer effective height；
The 3-D geometric model that step 2.1 and step 2.2 are established is imported into mesh generation software by step 2.3, makes its life
The unstrctured grid file approved at current main-stream finite element business software；
Step 2.4, the width by step 2.3 generates, narrow copper plate and strand grid file imported into nonlinear finite element point
Analyse software in, and according in practical casting process cross dimensions, taper be arranged, by 1/2 wide face copper coin, 1/2 narrow copper plate and
1/4 strand is built into 1/4 crystallizer-strand finite element model；
The steel physical parameter and copper coin physical parameter that are determined in step 1 are input to finite element analysis software by step 2.5
In, and distribution is corresponded to strand or the unit grid of copper coin；
Step 3, under the secondary development environment that finite element software is supported, establish coupling protection slag blanket and air gap distribution
Strand-crystallizer interface heat transfer model；
Step 4, the 1/4 crystallizer-strand finite element model established to step 2 complete contact, primary condition, side
The setting of boundary's condition and performance analysis, and calculating task is submitted with parallel computation pattern, make the strand node at meniscus to draw
Base speed is moved to mouth under crystallizer, carries out the calculating of period 1, and specific method is：
Contact pass of the funnel mould copper coin with the contact type of strand and between them is set separately in step 4.1
System and contact type；
The contact type set of the strand is deformable body, and copper coin is set as thermally conductive rigid body；
Contact relation between the strand and copper coin is " the thermally conductive rigid body of deformable body-", sets its contact type " to connect
It touches "；
The primary condition that step 4.2, setting model calculate：
Set the initial temperature of the initial temperature and strand of copper coin；
The mechanics and heat transfer boundary condition that step 4.3, setting model calculate：
Node is set on the strand plane of symmetry on node and the copper coin plane of symmetry along the temperature gradient of method phase, heat flow density and displacement
It is 0；
Apply interface heat transfer boundary condition in casting billet surface and the hot face of copper coin, wherein interface heat flux density is by interface heat transfer
Coefficient, casting blank surface temperature and copper coin hot-face temperature determine that interfacial heat transfer coefficient is true by calculating 3 established models of solution procedure
It is fixed；
Strand lowest level node is moved downward with casting speed along throwing direction；
Apply ferrostatic pressure at the solidification front of strand, value is determined by the vertical range of this to meniscus；
Apply convection current heat transfer boundary condition in copper coin flume surface；
Step 4.4 establishes Creep Equation, the creep behaviour of description steel under the high temperature conditions；
Step 4.5, setting model analyze operating mode：
The analysis operating mode of setting model is " thermal transient/machine creep ", and analysis time is node at meniscus with casting speed
It is moved under crystallizer the time required to mouth；
Each incremental step judges each unit of model before starting in setting solution procedure, if the unit is positioned at curved
Under lunar surface and crystallizer between mouth, then this element is activated, so that it is participated in heat/machine coupling and calculate, otherwise freeze this element, make it not
Participate in any calculating；
At the end of each incremental step, the liquid flux film thickness obtained when calculating interfacial heat transfer coefficient, solid-state are protected
Slag film thickness and air gap thickness write-in post-processing file；
Step 4.6 carries out region division to all units of model, activates parallel computation, and submit task to solver；
Step 5 continues to carry out 1/4 crystallizer-strand finite element model the calculating of multiple calculating cycles, until crystallizer
Temperature reaches stable state, completes the calculating conducted heat to casting blank solidification in funnel mould, and specific method is：
Step 5.1 judges whether current period is second calculating cycle, if so, calculating week by first in step 4
Unit when final carries out grid repositioning, and is saved as a new FEM calculation file；Otherwise, by upper one
A calculating cycle calculates unit when ending and carries out grid repositioning, and is saved as a new FEM calculation text
Part；
Material properties used in step 4 are imported into the new FEM calculation text that step 5.1 is separately deposited by step 5.2
In part, and each material properties are distributed to the strand and copper coin unit in current calculation cycle again；
Step 5.3 extends the strand unit at meniscus to throwing negative direction, and extension length is effective height of crystallizer
Degree；
Step 5.4, contact and contact relation according to step 4.1 setting model；
Step 5.5, the calculating primary condition of setting model：
Judge whether current calculation cycle is second calculating cycle, if so, by first calculating cycle end in step 4
When each node temperature as primary condition, to strand, the copper coin list in current period in addition to newly-generated unit in step 5.3
First temperature is initialized；Otherwise, each node temperature is as primary condition when the calculating of a upper calculating cycle being ended, to current week
Strand, copper coin cell temperature in phase in addition to newly-generated unit in step 5.3 are initialized；
Unit initial temperature newly-generated in step 5.3 in current calculation cycle is set as pouring temperature；
Step 5.6, the mechanics that finite element model is respectively completed according to step 4.3 to 4.6 methods and heat transfer boundary condition
Setting, the load of Creep Equation and the definition for analyzing operating mode, and divide zoning, carried out by parallel computation pattern in terms of
It calculates；
Step 5.7 is monitored copper coin hot-face temperature in calculating process, if copper coin hot-face temperature no longer occurs obviously
Variation, or enter cyclically-varying, then illustrate that current calculation cycle interior crystallizer-strand heat transfer system reaches stable state, to eventually
It only calculates, and extracts temperature, contact condition, casting blank deformation, slag blanket and the air gap point of strand-copper coin system in post-processing file
Otherwise cloth result of calculation repeats the calculating that step 5.1-5.6 completes next calculating cycle, until copper coin hot-face temperature
Reach stable.
As shown from the above technical solution, the beneficial effects of the present invention are：In a kind of funnel mould provided by the invention
Casting blank solidification Heat Transfer Calculation, can liquid covering slag, solid-state during accurate description funnel mould continuous casting sheet billet
The DYNAMIC DISTRIBUTION and copper plate of crystallizer of covering slag and air gap and Temperature Distribution, the contact condition of solidified shell, the contraction of strand
With the heat/mechanical behavior in sheet billets process of setting such as deformation.
Description of the drawings
Fig. 1 is the flow chart of casting blank solidification Heat Transfer Calculation in a kind of funnel mould provided in an embodiment of the present invention；
Fig. 2 is the signal of the 3-D geometric model of provided in an embodiment of the present invention 1/2 wide face copper coin and 1/2 narrow copper plate
Figure；
Fig. 3 is the schematic diagram of 1/4 funnel mould-strand finite element model provided in an embodiment of the present invention, wherein (a)
For front view, it is (b) upward view, is (c) right view, be (d) side view；
Fig. 4 is the copper plate temperature distribution schematic diagram of funnel mould provided in an embodiment of the present invention-strand model；
Fig. 5 is the strand Temperature Distribution schematic diagram of funnel mould provided in an embodiment of the present invention-strand model；
Fig. 6 is the wide face air gap distribution schematic diagram of funnel mould provided in an embodiment of the present invention-strand model.
Specific implementation mode
With reference to the accompanying drawings and examples, the specific implementation mode of the present invention is described in further detail.Implement below
Example is not limited to the scope of the present invention for illustrating the present invention.
The present embodiment is passed by taking certain steel mill CSP funnel moulds as an example using casting blank solidification in the funnel mould of the present invention
Hot computational methods calculate casting blank solidification heat transfer in the funnel mould.
Casting blank solidification Heat Transfer Calculation in a kind of funnel mould, as shown in Figure 1, including the following steps：
The quality of essential element in step 1, the steel grade QST420TM produced according to steel mill CSP continuous casting and rolling production lines
Percentage is consulted and obtains copper coin and cooling used in the physical parameter and funnel mould of this steel grade at different temperatures
The thermal coefficient of water, specific heat, density；
In steel grade QST420TM essential element and its percentage composition be respectively C0.047, Si0.022, Mn1.004,
P0.015, S0.0038, liquidus temperature and solidus temperature are respectively 1799.6K and 1776.1K, and latent heat of solidification is
280kJ/kg, liquid, solid steel specific heat be respectively 0.8kJ/ (kgK) and 0.6kJ/ (kgK), steel two-phase section specific heat by
Liquid, solid steel specific heat interpolation acquire；Steel grade QST420TM thermal coefficients at different temperatures, density, linear thermal expansion system
Number is as shown in table 1：
Thermal coefficient, density, the thermal linear expansion coefficients of 1 steel grade QST420TM of table at different temperatures
The elasticity modulus of steel can be acquired by following formula：
E=968-2.33T+1.9 × 10-3T2-5.18×10-7T3
In formula, E is elasticity modulus, GPa；T is temperature, DEG C；The yield limit of steel at different temperatures may be set to its
The 1/1000 of elasticity modulus at this temperature；
The Poisson's ratio of steel can be acquired by following formula：
V=0.278+8.23 × 10-5T
In formula, v is Poisson's ratio；
Pass through inspection information, it may be determined that the physical parameter of funnel mould copper coin and cooling water, concrete numerical value such as table 2
It is shown：
The physical parameter of table 2 copper coin and cooling water
Step 2, required according to steel mill CSP funnel mould copper coin structure charts and assembled in situ, the equipment such as taper setting and
Technological parameter establishes three-dimensional 1/4 strand-crystallizer heat/machine and couples finite element model, and specific implementation process includes：Establish geometry
Model, mesh generation, component assembling, physical parameter setting；
Step 2.1, according to steel mill CSP funnel mould copper coin blueprint 3 d modeling software SpaceClaim, establish such as
The 3-D geometric model of 1/2 wide face copper coin and 1/2 narrow copper plate shown in Fig. 2；
Step 2.2, according to live funnel mould matching requirements, including crystallizer width suitable for reading, narrow copper plate taper, knot
Brilliant device effective height, establishes the 3-D geometric model of 1/4 casting blank section at meniscus, and the height along throwing direction is crystallizer
Effective height；
The 3-D geometric model that step 2.1 and step 2.2 are established is directed respectively into ICEM softwares by step 2.3, and right
It carries out mesh generation, generates the unstrctured grid file of the entitled .pat of suffix；
Step 2.4, the width by step 2.3 generates, narrow copper plate and strand grid file imported into nonlinear finite element point
It analyses in software MSC.Marc, and is arranged according to the cross dimensions in practical casting process, taper, by 1/2 wide face copper coin, 1/2 narrow
Face copper coin and 1/4 strand are built into 1/4 crystallizer-strand finite element model as shown in Figure 3；
Crystallizer width suitable for reading is fixed as 1110 in the present embodiment, and narrow copper plate back draught is 0.9%.
Step 2-5, the steel physical parameter obtained in step 1 and copper coin physical parameter are input to Nonlinear Finite meta software
In MSC.Marc, and distribute to corresponding strand or copper coin unit grid.
Step 3, under the secondary development environment that finite element software MSC.Marc is supported, establish coupling protection slag blanket and gas
Strand-crystallizer interface heat transfer model of gap distribution, the selection of specific modeling process and parameter are as follows：
Liquid slag layer thermal resistance is calculated by following equation：
In formula, Rliq、Respectively liquid slag layer entire thermal resistance, liquid slag layer heat conduction item thermal resistance and liquid slag layer radiation term heat
Resistance, unit is m2K/W；dliq、kliq、EliqRespectively melt cinder layer thickness, liquid slag layer thermal coefficient, liquid slag layer absorptance, unit
Respectively m, W/ (mK), m-1；εs、εfThe respectively emissivity of strand and covering slag；Tcry、TsRespectively covering slag crystallization temperature
And casting blank surface temperature, unit K；σ is Boltzmann constant, and value is 5.67 × 10-8W/(m2·K4)；rfFor refractive index；
Solid slag layer thermal resistance is calculated by following formula：
In formula, Rsol、Respectively solid slag layer entire thermal resistance, solid slag layer heat conduction item thermal resistance and solid slag layer radiation term heat
Resistance, unit is m2K/W；dsol、ksol、EsolRespectively solid slag layer thickness, solid slag layer thermal coefficient, solid slag layer absorptance, unit
Respectively m, W/ (mK), m-1；εmFor the emissivity of crystallizer；Ta、TbIt is interface temperature, unit is K；
Air gap thermal resistance is calculated by following formula：
In formula, Rair、Respectively air gap entire thermal resistance, air gap heat conduction item thermal resistance and air gap radiation term thermal resistance, unit
It is m2K/W；dair、kair、EairRespectively air gap thickness, air gap thermal coefficient, air gap absorptance, unit are respectively m, W/
(m·K)、m-1；TmFor crystallizer hot-face temperature, unit K；
Solid slag layer-crystallizer interface resistance is determined by following formula：
In formula, RintIndicate solid slag layer-crystallizer interface resistance, unit m2K/W；
Since each dielectric layer heat flux is equal, there are following relationships between liquid slag blanket, the gentle gap layer of solid-state slag blanket：
If (Ts＞ Tcry)
If (Ts＜ Tcry)
By solving above formula, the DYNAMIC DISTRIBUTION of liquid covering slag, solid-state covering slag and air gap is can get, so as into one
Step acquires the thermal resistance of each dielectric layer；
The coefficient of heat transfer is determined by following formula between green shell-copper coin：
In formula, h is crystallizer-strand interface heat exchange coefficient, and unit is W/ (m2·K)；
By detecting the physical characteristic of scene CSP covering slags, the covering slag physical parameter calculated needed for interface heat transfer is obtained；
The concrete numerical value that the parameters used in above formula are solved in the present embodiment is as shown in table 3：
Table 3 solves the physical parameter needed for crystallizer-strand interface heat transfer model
Step 4, the 1/4 crystallizer-strand finite element model established to step 2 complete contact, primary condition, side
The setting of boundary's condition and performance analysis, and calculating task is submitted with parallel computation pattern, make the strand node at meniscus to draw
Base speed is moved to mouth under crystallizer, carries out the calculating of period 1, and specific method is：
Contact pass of the funnel mould copper coin with the contact type of strand and between them is set separately in step 4.1
System and contact type；
The contact type set of the strand is deformable body, and copper coin is set as thermally conductive rigid body；
Contact relation between the strand and copper coin is " the thermally conductive rigid body of deformable body-", sets its contact type " to connect
It touches "；
The primary condition that step 4.2, setting model calculate：
The initial temperature of strand node is set as pouring temperature, i.e. 1824K sets the initial temperature of copper coin as 323K.
The mechanics and heat transfer boundary condition that step 4.3, setting model calculate；
Node along the displacement of method phase is 0 on node and the copper coin plane of symmetry on the strand plane of symmetry；The copper coin degree of freedom on a node basis is 0,
Along it is each to displacement be 0；Strand lowest level is moved down with casting speed 4.0m/s along throwing direction close to node at meniscus；
In view of there is ferrostatic pressure to act on solidification front in actual production process, therefore, applying ferrostatic pressure
During, need the position for determining solidification front first；In the present embodiment, with solidus temperature, i.e. before 1776K is as solidification
The temperature on edge, and thereby determine that the position of solidification front；During loading mechanic boundary condition, each strand unit 8 is saved
Point temperature is averaging, if solidus temperature is just between certain adjacent two cell-averages temperature, adjacent Unit two is total to herein
It enjoys and applies ferrostatic pressure on elemental area, conversely, then not applying any load in period；The concrete numerical value of ferrostatic pressure is under
Formula determines：
P=ρmolten gh
In formula, P is ferrostatic pressure, unit Pa；ρmeltenFor molten steel density, value takes 7200kg/m3；G adds for gravity
Speed, unit m/s2；H is pool depth, unit m；
Apply transmission of heat by contact boundary condition in casting billet surface and the hot face of copper coin, heat flow density can be expressed from the next：
Q=h (Ts-Tm)
In formula, q is interface heat flux density, and unit is W/ (m2)；H is crystallizer-strand interface heat exchange coefficient, unit W/
(m2·K)；TsAnd TmThe respectively temperature in the hot face of casting billet surface and copper coin, unit K；Interface heat exchange coefficient in above formula is by step
The rapid 3 interface heat transfer models established acquire；It is worth noting that, by solving the Nonlinear System of Equations in the model, liquid
The gentle gap thickness of thickness of slag layer, solid-state thickness of slag layer can together be acquired with interface heat exchange coefficient, and be stored in post-processing text
Part；
The heat flow density of strand and copper coin plane of symmetry upper edge method phase is set as 0, temperature gradient 0；
Copper plate of crystallizer sink side heat transfer modes are set as heat convection, and assume cooling water temperature from entrance (309K) line
Property is changed to outlet (317K), and convection transfer rate is determined by following formula：
In formula, hwFor convection transfer rate, unit is W/ (m2K), ρw、vw、kw、μw、cwRespectively the density of cooling water,
Flow velocity, thermal coefficient, dynamic viscosity, specific heat, each variable unit is respectively kg/m3、m/s、W/(m·K)、Pa·s、J/(kg·
K)；D is the hydraulic diameter of sink, unit m；
Step 4.4 establishes Creep Equation, the creep behaviour of description steel under the high temperature conditions；
In view of steel has creep behaviour under the high temperature conditions, traditional elastic-plastic model can not accurately retouch it
It states, therefore describes the strain-stress relation in its creep stage in the present embodiment using following calculation formula：
N=6.365-4.521 × 10-3T+1.439×10-6T2
M=-1.362+5.761 × 10-4T+1.982×10-8T2
In formula,Respectively equivalent strain rate and equivalent stress, unit are respectively s-1、MPa；C is pre-exponential factor,
Its value is related with carbon content wc in steel；N is the temperature index of correlation of equivalent stress, and m is the temperature index of correlation of time；Q is compacted
Become the ratio of activation energy and gas constant, value 17160K-1；T is time, unit s；
Step 4.5, the analysis operating mode of setting model；
The analysis operating mode type of setting model is thermal transient/machine creep, and the whole operating mode time is 15s, is drawn because CSP stablizes
Speed is 4m/s, and crystallizer effective height is 1m, therefore unit is moved to mouth needs under crystallizer with casting speed at meniscus
15s；
Each incremental step judges each unit before starting in setting solution procedure, if its current location is just in knot
Below brilliant device meniscus, under crystallizer more than mouth, then the unit is activated, so that it is participated in mechanics and Calculation of Heat Transfer, conversely, then freezing
This element makes it be not involved in any calculating, and does not appear in post-processing file；
At the end of each incremental step, adjoint interfacial heat transfer coefficient obtains simultaneously during calculating strand-copper coin interface heat transfer
Liquid, admittedly protect slag blanket, air gap DYNAMIC DISTRIBUTION write-in post-processing file；
Step 4.6 carries out region division to all units of model, activates parallel computation, and submit task to solver；
Step 5 continues to carry out 1/4 crystallizer-strand finite element model the calculating of multiple calculating cycles, until crystallizer
Temperature reaches stable state, completes the calculating conducted heat to casting blank solidification in funnel mould, and specific method is：
Step 5.1 judges whether current period is second calculating cycle, if so, calculating week by first in step 4
Unit when final carries out grid repositioning, and is saved as a new FEM calculation file (.mud files)；
Otherwise, a upper calculating cycle is calculated into unit when ending and carries out grid repositioning, and saved as one it is new limited
First calculation document (.mud files)；
Material properties used in step 4 are imported into the new FEM calculation text that step 5.1 is separately deposited by step 5.2
In part, and each material properties are distributed to the strand and copper coin unit in current calculation cycle again；
Step 5.3 extends the strand unit at meniscus to throwing negative direction, and extension length is effective height of crystallizer
Degree；
In the present embodiment, the vertical range of crystallizer meniscus to lower mouth is equal to 1m.
Step 5.4, contact and contact relation according to step 4.1 setting model；
Step 5.5, the calculating primary condition of setting model：
Judge whether current calculation cycle is second calculating cycle, if so, by first calculating cycle end in step 4
When each node temperature as primary condition, to strand, the copper coin list in current period in addition to newly-generated unit in step 5.3
First temperature is initialized；Otherwise, each node temperature is as primary condition when the calculating of a upper calculating cycle being ended, to current week
Strand, copper coin cell temperature in phase in addition to newly-generated unit in step 5.3 are initialized；
Unit initial temperature newly-generated in step 5.3 in current calculation cycle is set as pouring temperature, i.e. 1824K；
Step 5.6, the mechanics that finite element model is respectively completed according to step 4.3 to 4.6 methods and heat transfer boundary condition
Setting, the load of Creep Equation and the definition for analyzing operating mode, and divide zoning, carried out by parallel computation pattern in terms of
It calculates；
Step 5.7 is monitored copper coin hot-face temperature in calculating process, if copper coin hot-face temperature no longer occurs obviously
Variation, or enter cyclically-varying, then illustrate that current calculation cycle interior crystallizer-strand heat transfer system reaches stable state, to eventually
It only calculates, and extracts temperature, contact condition, casting blank deformation, slag blanket and the air gap point of strand-copper coin system in post-processing file
Otherwise cloth result of calculation repeats the calculating that step 5.1-5.6 completes next calculating cycle, until copper coin hot-face temperature
Reach stable.
In the present embodiment, after to be calculated, infundibular ganglion as shown in Figure 4 is extracted in MSC.Mentat post-processes file
Contact condition, liquid slag blanket, solid-state slag blanket and such as Fig. 6 between brilliant device copper plate temperature, strand temperature as shown in Figure 5, copper coin-strand
Shown in air gap the result of calculations such as DYNAMIC DISTRIBUTION, analyze it, discuss that existing mold structure, covering slag physics are special
Property, the reasonability of casting process parameters.
The present embodiment combination attached drawing does preliminary analysis to the Heat transfer of certain steel mill CSP funnel moulds：
From attached drawing 4 as can be seen that factory CSP funnel mould copper coin hot-face temperature distributed poles are uneven, deposited at meniscus
In the larger temperature difference, in casting process, huge temperature gradient can cause larger thermal strain at copper coin meniscus so that this
Larger plastic deformation very likely occurs for one region.Device to be crystallized is offline to be cooled to room temperature, the local meeting being plastically deformed
Concentrated stress is generated, and easily causes copper coin face crack.To avoid such case, it can with due regard to reduce copper coin back
Sink width increases sink quantity, the inhomogeneities of copper coin hot-face temperature when being produced with reducing.
From attached Figures 5 and 6 as can be seen that inside crystallizer, the wide surface side corner of strand and deviation angular zone presence are thicker
Air gap, and the presence of air gap causes the high temperature that strand deviates angular zone.Under the high temperature conditions in view of steel, intensity can obviously drop
Low, deviateing the high temperature of angular zone very likely makes green shell at this that can not bear huge ferrostatic pressure, in turn results in bleed-out thing
Therefore.To avoid the generation of this phenomenon, it should suitably increase the back draught of copper coin through-thickness, to compensate because of strand corner edge
The contraction of thickness direction reduces air gap thickness, strand deflecting angle temperature is made to reduce as far as possible.
Finally it should be noted that：The above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, it will be understood by those of ordinary skill in the art that：Its according to
So can with technical scheme described in the above embodiments is modified, either to which part or all technical features into
Row equivalent replacement；And these modifications or replacements, it does not separate the essence of the corresponding technical solution, and the claims in the present invention are limited
Fixed range.
Claims (5)
1. casting blank solidification Heat Transfer Calculation in a kind of funnel mould, it is characterised in that：Include the following steps：
Step 1 consults the physical parameter for obtaining steel according to the steel grades of simulation, while consulting acquisition funnel mould and being used
Copper coin and cooling water thermal physical property parameter；
Step 2 establishes Three Dimensional Thermal/couple of force conjunction finite element model according to funnel mould-strand system；
Step 3, under the secondary development environment that finite element software is supported, establish coupling protection slag blanket and air gap distribution casting
Base-crystallizer interface heat transfer model；
Step 4, the 1/4 crystallizer-strand finite element model established to step 2 complete contact, primary condition, perimeter strip
The setting of part and performance analysis, and calculating task is submitted with parallel computation pattern, make the strand node at meniscus with throwing speed
Degree is moved to mouth under crystallizer, carries out the calculating of period 1；
Step 5 continues to carry out 1/4 crystallizer-strand finite element model the calculating of multiple calculating cycles, until mould temperature
Reach stable state, completes the calculating conducted heat to casting blank solidification in funnel mould.
2. casting blank solidification Heat Transfer Calculation in a kind of funnel mould according to claim 1, it is characterised in that：Step
1 each physical parameter specifically includes：
According to the mass percentage of essential element in the steel grade of wanted simulation casting, consult obtain the steel liquidus temperature,
Solidus temperature, latent heat of solidification and the steel grade in process of setting thermal coefficient, density, specific heat and coefficient of thermal expansion with temperature
Variation；Consult obtain steel elasticity modulus, Poisson's ratio and yield limit parameter at different temperatures and copper plate of crystallizer with
Thermal coefficient, specific heat and the density physical parameter of cooling water.
3. casting blank solidification Heat Transfer Calculation in a kind of funnel mould according to claim 1, it is characterised in that：It is described
The specific method of step 2 is：
Step 2.1 pours into a mould cross dimensions according to funnel mould copper coin structure chart and strand, establishes 1/2 wide face copper plate of crystallizer
With the 3-D geometric model of 1/2 leptoprosopy crystallizer copper board combining structure；
Step 2.2, according to funnel mould width suitable for reading, narrow copper plate taper and crystallizer effective height, establish meniscus
The 3-D geometric model for locating 1/4 casting blank section, the height along throwing direction are crystallizer effective height；
The 3-D geometric model that step 2.1 and step 2.2 are established is imported into mesh generation software by step 2.3, its generation is made to work as
The unstrctured grid file that preceding mainstream finite element business software is approved；
It is soft that step 2.4, the width by step 2.3 generates, narrow copper plate and strand grid file imported into non linear finite element analysis
In part, and it is arranged according to the cross dimensions in practical casting process, taper, by 1/2 wide face copper coin, 1/2 narrow copper plate and 1/4 casting
Base is built into 1/4 crystallizer-strand finite element model；
The steel physical parameter and copper coin physical parameter that are determined in step 1 are input in finite element analysis software by step 2.5, and
Distribution is corresponded to strand or the unit grid of copper coin.
4. casting blank solidification Heat Transfer Calculation in a kind of funnel mould according to claim 1, it is characterised in that：It is described
The specific method of step 4 is：
Step 4.1, the contact type that funnel mould copper coin and strand is set separately and contact relation between them and
Contact type；
The contact type set of the strand is deformable body, and copper coin is set as thermally conductive rigid body；
Contact relation between the strand and copper coin is " the thermally conductive rigid body of deformable body-", sets its contact type as " contact "；
The primary condition that step 4.2, setting model calculate：
Set the pouring temperature of the initial temperature and strand of copper coin；
The mechanics and heat transfer boundary condition that step 4.3, setting model calculate：
Node is along the temperature gradient of method phase, heat flow density and displacement on node and the copper coin plane of symmetry on the setting strand plane of symmetry
0；
Apply interface heat transfer boundary condition in casting billet surface and the hot face of copper coin, wherein interface heat flux density by interfacial heat transfer coefficient,
Casting blank surface temperature and copper coin hot-face temperature determine that interfacial heat transfer coefficient is determined by calculating 3 established models of solution procedure；
Strand lowest level node is moved downward with casting speed along throwing direction；
Apply ferrostatic pressure at the solidification front of strand, value is determined by the vertical range of this to meniscus；
Apply convection current heat transfer boundary condition in copper coin flume surface；
Step 4.4 establishes Creep Equation, the creep behaviour of description steel under the high temperature conditions；
Step 4.5, setting model analyze operating mode：
The analysis operating mode of setting model is " thermal transient/machine creep ", and analysis time is that node is moved with casting speed at meniscus
Under to crystallizer the time required to mouth；
Each incremental step judges each unit of model before starting in setting solution procedure, if the unit is located at meniscus
Between mouth under crystallizer, then this element is activated, so that it is participated in heat/machine coupling and calculate, otherwise freeze this element, it is made to be not involved in
Any calculating；
At the end of each incremental step, the liquid flux film thickness, the solid-state flux film that will be obtained when calculating interfacial heat transfer coefficient
Thickness and air gap thickness write-in post-processing file；
Step 4.6 carries out region division to all units of model, activates parallel computation, and submit task to solver.
5. casting blank solidification Heat Transfer Calculation in a kind of funnel mould according to claim 1, it is characterised in that：It is described
The specific method of step 5 is：
Step 5.1 judges whether current period is second calculating cycle, if so, by first calculating cycle end in step 4
When unit carry out grid repositioning, and saved as a new FEM calculation file；Otherwise, upper one is counted
It calculates unit when computation of Period ends and carries out grid repositioning, and saved as a new FEM calculation file；
Material properties used in step 4 are imported into the new FEM calculation file that step 5.1 is separately deposited by step 5.2,
And each material properties are distributed to strand and copper coin unit in current calculation cycle again；
Step 5.3 extends the strand unit at meniscus to throwing negative direction, and extension length is the effective height of crystallizer；
Step 5.4, contact and contact relation according to step 4.1 setting model；
Step 5.5, the calculating primary condition of setting model：
Judge whether current calculation cycle is second calculating cycle, if so, by when first calculating cycle ends in step 4
Each node temperature is as primary condition, to the strand in current period in addition to newly-generated unit in step 5.3, copper coin unit temperature
Degree is initialized；Otherwise, each node temperature is as primary condition when the calculating of a upper calculating cycle being ended, in current period
Strand, copper coin cell temperature in addition to newly-generated unit in step 5.3 are initialized；
Unit initial temperature newly-generated in step 5.3 in current calculation cycle is set as pouring temperature；
Step 5.6, be respectively completed according to step 4.3 to 4.6 methods the mechanics of finite element model and the setting of heat transfer boundary condition,
The load of Creep Equation and the definition for analyzing operating mode, and zoning is divided, it is calculated with parallel computation pattern；
Step 5.7 is monitored copper coin hot-face temperature in calculating process, if copper coin hot-face temperature no longer occurs obviously to become
Change, or enter cyclically-varying, then illustrates that current calculation cycle interior crystallizer-strand heat transfer system reaches stable state, to terminate
It calculates, and extracts temperature, contact condition, casting blank deformation, slag blanket and the air gap distribution of strand-copper coin system in post-processing file
Otherwise result of calculation repeats the calculating that step 5.1-5.6 completes next calculating cycle, until copper coin hot-face temperature reaches
To stabilization.
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