CN104148387B - The hot core milling method of a kind of continuous casting - Google Patents

Abstract

The invention discloses the hot core milling method of a kind of continuous casting, once cut anterior horizontal segment at casting blank of continuous casting machine, near casting blank solidification end position, roller mill is set, be greater than minimum start rolling temperature T at milling train position casting blank surface temperature_{R_min}Condition under, obtain the liquid core rate δ of hot core rolling position place strand, if liquid core rate δ is 0, milling train is with mill speed v_rStrand is carried out to drafts and be not less than minimum drafts Δ H_minHot core rolling. The method utilizes continuous casting waste heat to implement online hot core rolling, saves required power, significantly energy-conservation; Greatly reduce casting blank solidification defect, obtain high-quality rolling continuous casting base; Keep the matching of the pulling rate of mill speed and conticaster, pulling rate good stability, controls simple; After milling train, without fan-shaped section is set, directly replace with cast blank conveying roller table, save equipment investment; Same crystallizer specification continuous casting billet is rolled into the continuous casting billet product of various thickness specifications within the scope of certain thickness by the hot core rolling of direct-on-line, realize thickness of strand on-line control.

Description

The hot core milling method of a kind of continuous casting

Technical field

The present invention relates to metal rolled field, relate in particular to the hot core milling method of a kind of continuous casting.

Background technology

The metal rolled energy-conservation important problem in one, rolling field instantly that becomes, iron and steel circle all adopts the whole bag of tricks to reduceRequired power. Current known technology is mainly that continuous casting billet hot charging heat is sent, Direct Rolling etc. (1) continuous casting billet Direct Rolling (hot chargingTemperature is more than 1100 DEG C), be called for short CC-DR (ContinuousCasting-DirectRolling), continuous casting billet is without addingHot stove, and directly send mill milling by corner heat patching device in course of conveying. (2) Hot Charging of Continuous Casting Slab Direct Rolling (shove charge temperatureDegree A3～1100 DEG C), be called for short CC-HDR (ContinuousCasting-HotDirectRolling), refer to that continuous casting billet is notThrough heating furnace and in course of conveying by concurrent heating and soaking, steel billet is reached and can roll temperature, directly send mill milling. ButThe difficult point that realizes continuous casting billet Direct Rolling is the reasonable link of defect free slab production, the production of high temperature strand, continuous casting and tandem rollingWith the technical requirement such as Flexible Production and integrated production management system. It is the key of Direct Rolling that defect free slab is produced, alsoBe the key of conventional continuous casting, how improving slab quality is also one of difficult problem instantly. And these methods are all that continuous casting billet is cutAfter cutting, enter rolling process, strand heat loss is very large again, is difficult to obtain high temperature strand.

Liquid core rolling refers to the rolling of carrying out when steel billet core is liquid state or semisolid, this method be continuous casting billet withoutCutting utilizes continuous casting waste heat to be rolled, and strand heat loss is little, and rolling essence is squeezed time rear portion liquid core of core liquid core, coreThe broken recrystallization of portion's crystal region dendrite. Such as Granted publication number for CN102189102, the day for announcing be on February 6th, 2013,Name is called in the Chinese patent literature of " the online doctor roll formula of a kind of conticaster is depressed greatly liquid core rolling method ", at slab casterHorizontal segment solidification end arranges the duo mill in a big roller footpath, and strand is carried out to single pass heavy reduction liquid core rolling, therebyRemove center porosity and segregation, internal fissure etc., improve slab quality, refinement interior tissue. The difficult point of the method is strandLiquid core Position Control is had relatively high expectations, and rolling mill screwdown position and online seizure on the opportunity of depressing are difficult; To the control of casting machine pulling rate, two cold controlsSystem all requires very high, implements difficulty larger.

Hot core rolling refers to that steel billet is in the time of hot-working rolling, and core temperature is high, under the low this state of temperature of surface temperatureRolling deformation, with the difference of conventional hot rolling be that conventional hot rolling steel billet entire body temperature is even, each several part resistance of deformation is even, hot core rollsTime processed, core high temperature hot deformation resistance is low, and plastic deformation preferentially occurs steel billet core.

Summary of the invention

For the deficiencies in the prior art, the technical problem to be solved in the present invention is to provide a kind of hot core of continuous casting of implementing to be easy toMilling method.

For solving the problems of the technologies described above, the present invention adopts following technical scheme:

The hot core milling method of a kind of continuous casting, once cuts anterior horizontal segment near casting blank solidification end position at casting blank of continuous casting machineInstall roller mill, in described milling train position, casting blank surface temperature is greater than minimum start rolling temperature T_{R_min}Condition under, obtain heatThe liquid core rate δ of core rolling position place strand also judges whether this liquid core rate δ is 0, if liquid core rate δ is 0, with mill speed v_rRightStrand carries out drafts and is more than or equal to minimum drafts Δ H_minOnline hot core rolling.

As further optimization of the present invention, minimum start rolling temperature T_{R_min}＝A_r3-40 DEG C, wherein, A_r3That this steel grade is coldBut time, in austenite, start to separate out ferritic critical-temperature line.

As further optimization of the present invention, minimum drafts Δ H_min＝max[H·(ε_v+ε_l), μ S], wherein, H isThe slab thickness at inlet of rolling mill place, unit is mm; ε_VFor solidification shrinkage rate, the % of unit; ε_lFor linear shrinkage, the % of unit; S isCasting machine mold liquid level is to the distance of described milling train position, the m of unit; μ is light reduction ratio, and span is 0.3～1.4mm/m.

As further optimization of the present invention, if liquid core rate δ is greater than 0, described milling train carries out drafts to strand and is greater thanOr equal minimum drafts Δ H_min' rolling, minimum drafts Δ H_min′＝max[H·(ε_v+ε_l+ δ), μ S], wherein, H isThe slab thickness at inlet of rolling mill place, unit is mm; ε_VFor solidification shrinkage rate, the % of unit; ε_lFor linear shrinkage, the % of unit; δ isMilling train position liquid core rate, the % of unit; S is the distance of casting machine mold liquid level to described milling train position, the m of unit; μ is for gently depressingRate, span is 0.3～1.4mm/m.

As further optimization of the present invention, the mill speed of described milling train $v_r=\frac{H}{[2R(1-\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2})+H\·(1-\mathrm{\ϵ})]\·\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2}}\·v_0\·\mathrm{\λ},$ Wherein, H represents the slab thickness at inlet of rolling mill place, and unit is mm; B represents strand width, and unit is mm; R represents working roll halfFootpath, unit is mm; ε represents the reduction ratio of rolling, the % of unit; v₀Represent casting speed, unit is m/min; λ is that the speed of rolls is repaiiedPositive coefficient, span is 0.9～1.1.

As further optimization of the present invention, the rear portion rollgang of described milling train is with linear velocity v₂Carry, described inThe linear velocity of milling train rear portion rollgangWherein, k is speed correction factor after machine, and span is0.9～1.1。

As further optimization of the present invention, if liquid core rate δ is greater than 0, described milling train is with mill speed v_r' strand is enteredRow rolling, mill speed ${v_r}^{\′}=\frac{H\·[b-\mathrm{\δ}(b-H+\mathrm{\δ}\·H)]}{[2R(1-\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2})+H\·(1-\mathrm{\ϵ})]\·b\·\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2}}\·v_0\·\mathrm{\λ},$ Wherein, H represents that milling train entersThe slab thickness at mouth place, unit is mm; B represents strand width, and unit is mm; δ represents milling train position liquid core rate, the % of unit; R tableShow working roll radius, unit is mm; ε represents the reduction ratio of rolling, the % of unit; v₀Represent casting speed, unit is m/min; λ isSpeed of rolls correction factor, span is 0.9～1.1.

As further optimization of the present invention, the rear portion rollgang of described milling train is with linear velocity v₂' carry, described inThe linear velocity of milling train rear portion rollgangWherein, k is speed correction factor after machine,Span is 0.9～1.1.

Compared with prior art, the main advantage of technical solution of the present invention is as follows:

(1) utilize continuous casting waste heat to implement online hot core rolling, exempt heating again before rolling, and hot core segment resistance of deformationResistance of deformation when solidifying completely, thereby can significantly save required power, significantly energy-conservation.

(2) to being connected between continuous casting and rolling without being strict with, realize easily; Simultaneously owing to implementing hot core rolling, to liquid coreAccurate requirement is not done in position, and depressing position and opportunity are controlled well, conticaster is not produced to the extra requirement of controlling, and implements difficultyLittle.

(3) control simply, pulling rate good stability, strand throwing is smooth and easy; Keep mill speed and conticaster pulling rateJoining property, drives thereby eliminate milling train the impact that casting machine fan-shaped section is driven.

(4) continuous casting billet is implemented to online hot core rolling, can reduce solidification shrinkage and the Solid State Contraction shadow to slab qualityRing, greatly reduce casting blank solidification defect, obtain high-quality rolling continuous casting base.

(5) after milling train without fan-shaped section is set again, can directly replace with cast blank conveying roller table, save equipment investment.

(6) can roll into various within the scope of certain thickness in the hot core rolling of direct-on-line to same crystallizer specification continuous casting billetThe continuous casting billet product of thickness specification, realizes thickness of strand on-line control.

Brief description of the drawings

Fig. 1 is the flow chart of the hot core milling method of continuous casting of the present invention.

Detailed description of the invention

The hot core milling method of continuous casting of the present invention as shown in Figure 1, once cuts anterior horizontal segment at casting blank of continuous casting machine closeCasting blank solidification end position arranges roller mill, and establishing this position maximum liquid core thickness, to account for the percentage of slab thickness before rolling be liquidCore rate is δ, is greater than minimum start rolling temperature T at this milling train position casting blank surface temperature_{R_min}Condition under, obtain liquid core rate δ and sentenceBreaking, whether it is 0, if liquid core rate δ is 0, this milling train is with mill speed v_rStrand is carried out to drafts and be not less than minimum draftsΔH_minContinuous online hot core rolling, make the plastic deformation of strand center, rolling seam strand center porosity and shrinkage cavity etc., andCarry out austenite recrystallization with refinement core tissue thereby smash the thick column crystal of core, ensure strand table after hot core rolling simultaneouslyFace quality is good, keeps the matching of the pulling rate of mill speed and conticaster, and pulling rate good stability is controlled simple.

Wherein, rolling drafts Δ H is the product of the front slab thickness H of rolling and reduction ratio ε, so as long as known rollingReduction ratio, just can obtain drafts.

The setting principle of the minimum reduction ratio of hot core rolling

In the hot core operation of rolling, because hot core segment resistance of deformation is much smaller than the surperficial resistance of deformation of solidifying completely, castingThe inner plasticity of base is greater than surface plasticity, and when rolling, inner preferential distortion, is so just different from traditional hot rolling outside and is first out of shape, normal" pressing the degree of depth " required minimum reduction ratio of rule hot rolling (is about) can greatly reduce.

What slab quality problem produced is coagulation defect at all. Steel occurs from liquid state to solid-state cooling procedureVolume reduces phenomenon and is called contraction. Contraction is to cause many defects in strand as the root of shrinkage cavity, loose, crackle, stress, distortion etc.This reason. Molten steel is cooled to normal temperature all will experience three contraction phases from pouring temperature:

1. the liquid contraction phase: the volume contraction that molten steel is cooled to from pouring temperature the liquidus temperature that starts to solidify is liquidState is shunk. 100 DEG C of the every declines of molten steel, cubical contraction is about 1.5～1.75%. In casting process, temperature liquidus curve withOn molten steel, completely in liquid in-core. Liquid contraction occurs in liquid core inner, and the volume that it brings reduces completely can be by continuouslyThe molten steel pouring into supplements, and therefore slab quality is not almost affected.

2. the solidification shrinkage stage: solidifying of steel is to carry out in two-phase section, and what produce in solidification temperature range is punctured intoSolidification shrinkage, comprises by liquid state and shrinking to solid-state state change and temperature reduction two parts. The solidification shrinkage of steel is decided by itChemical composition, for carbon steel, depends primarily on phosphorus content C%. The solidification shrinkage rate of carbon steel is as table 1:

C％	0.10	0.25	0.35	0.45	0.70
						εV％	2.0	2.5	3.0	4.3	5.3

The solidification shrinkage rate ε of table 1-carbon steel_VRelation with phosphorus content

Solid rate in the two-phase section of strand center reaches predetermined value for example after 0.4～0.6, and dendrite develops into closely knit netNetwork structure, has stoped molten steel to flow interdendritic. Under the inadequate condition of casting compencation, will cause the contracting of strand insideHole and rarefaction defect, the shrinkage cavity of solidification shrinkage to strand, loose and crackle have a direct impact.

3. the Solid State Contraction stage: after solidifying completely, steel to normal temperature, Solid State Contraction can occur by solidus temperature. Consolidating of carbon steelState is shunk and is divided into three phases: contraction before perlitic transformation, roll over altogether the receipts after expansion and the perlitic transformation of tourContracting, whole Solid State Contraction rate is three's sum. The Solid State Contraction of steel is produce stress, distortion and crackle in strand at all formerCause. Solid State Contraction rate is cubical contraction, and its component in slab thickness direction is linear shrinkage ε_l. Come for carbon steelSay linear shrinkage ε_lSee the following form 2 with the relation of phosphorus content C%:

C％	0.08	0.14	0.35	0.45	0.55	0.60
							εl％	2.47	2.46	2.4	2.35	2.31	2.18

The linear shrinkage ε of table 2-carbon steel_lRelation with phosphorus content

Therefore, in the hot core operation of rolling, main consideration overcomes solidification shrinkage and the impact of Solid State Contraction on slab quality,In order to solve casting blank solidification defect, the reduction ratio ε that we set hot core rolling is more than or equal to minimum reduction ratio ε_min, and minimumReduction ratio is:

ε_min＝ε_v+ε_l(1)

Wherein, solidification shrinkage rate ε_VCubical contraction, the % of unit, solidification shrinkage process is because base shell forms, itsCubical contraction is depressed in process and is mainly compressed to carry out feeding by thickness direction in rolling, therefore by the cubical contraction ε solidifying_VDirectly correspond to the reduction ratio of thickness direction.

Because the drafts Δ H=H ε of rolling, so minimum drafts Δ H_minAs follows:

ΔH_min＝H·ε_min＝H·(ε_v+ε_l)(2)

Wherein, H is slab thickness before rolling, and unit is mm. Therefore the drafts Δ H that, sets hot core rolling is not less thanLight reduction Δ H_min。

In addition,, in the situation that hot core is depressed anterior casting machine fan-shaped section and do not dropped into dynamic soft-reduction, minimum drafts also shouldMeet following condition:

ΔH_min＝μ·S(3)

Wherein, S is the distance of casting machine mold liquid level to milling train position, the m of unit; μ is light reduction ratio, and span is0.3～1.4mm/m, its value is subject to the impact of solidification and contraction coefficient and the strand size of steel grade.

In sum, the minimum drafts Δ of hot core rolling H_minShould meet formula (2) and (3) simultaneously and get in bothMaximum, that is:

ΔH_min＝max[H·(ε_v+ε_l)，μ·S](4)

Therefore the drafts Δ H that, sets hot core rolling is not less than minimum drafts Δ H_min。

In actual application, do not get rid of in the hot core operation of rolling, because pulling rate changes, the degree of superheat is high, two cold variationsCause strand liquid core to arrive hot core rolling position etc. factor, at this moment liquid core rate δ is greater than 0, and therefore hot core rolling will be considered first by liquidCore metal is extruded solidified shell inner chamber and is eliminated the impact that metal liquid shrinks, now minimum reduction ratio ε_min' be:

ε_min′＝ε_v+ε_l+δ(5)

Because the drafts Δ H=H ε of rolling, so minimum drafts Δ H_min' as follows:

ΔH_min′＝H·ε_min′＝H·(ε_v+ε_l+δ)(6)

Therefore, the drafts Δ H of setting rolling is not less than minimum drafts Δ H_min'。

In addition,, in the situation that hot core is depressed anterior casting machine fan-shaped section and do not dropped into dynamic soft-reduction, minimum drafts also shouldMeet following condition:

ΔH_min′＝μ·S(7)

In sum, in the situation that strand does not solidify completely, liquid core rate δ is greater than at 0 o'clock, the minimum drafts Δ of rollingH_min' should meet formula (6) and (7) simultaneously and get the maximum in both, that is:

ΔH_min′＝max[H·(ε_v+ε_l+δ)，μ·S](8)

Therefore, the drafts Δ H of setting rolling is not less than minimum drafts Δ H_min'。

The setting principle of the minimum start rolling temperature of casting billet surface

For the defects such as rolling crack well do not appear in cc billet surface quality after ensureing hot core rolling, the hot core of General Requirements rollsCasting billet surface minimum temperature before system:

T_{R_min}＝A_r3-40℃(9)

In formula, A_r3It is the critical-temperature line that this steel grade starts to separate out F (ferrite) when cooling in A (austenite). A_r3Calculating can adopt such as A of empirical equation_r3=910-310C-80Mn-20Cu-15Cr-55Ni-80Mo+0.35 (h-8), formulaMiddle h is product thickness after rolling.

The control principle of hot core mill speed

In the hot core operation of rolling, to consider how to keep matching between mill speed and the pulling rate of conticaster to reduceMilling train drives the impact that casting machine fan-shaped section is driven, and also will consider how to avoid being with the integrated rolling of casting to conticaster crystallizationDevice liquid level causes fluctuation. Thereby, in the hot core operation of rolling, the mill speed of milling train (being roll linear velocity) v_rFollow conticasterCasting speed v₀, the linear velocity v of milling train rear portion rollgang₂Follow milling train muzzle velocity, and then also follow the strand of conticasterPulling rate v₀, its correlation is as follows:

When complete hot core rolling, liquid core rate δ is 0 o'clock, determines roll linear velocity v according to formula (10) below_rAnd machineRear drive line speed (being the linear velocity of milling train rear portion rollgang) v₂：

$\begin{array}{c}{v}_r=\frac{H}{[2R(1-\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2})+H\·(1-\mathrm{\ϵ})]\·\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2}}\·v_0\·\mathrm{\λ},\\ v_2=\frac{1}{1-\mathrm{\ϵ}}\·v_0\·k\end{array}---\left(10\right)$

In above formula, H represents the slab thickness at inlet of rolling mill place, and unit is mm; B represents strand width, and unit is mm;δ represents milling train position liquid core rate, the % of unit; R represents working roll radius, and unit is mm; ε represents the reduction ratio of rolling, the % of unit,Reduction ratio ε is preferably more than or equalsv₀Represent casting speed, unit is m/Min; λ is speed of rolls correction factor, and span is 0.9～1.1; K is speed correction factor after machine, and span is 0.9～1.1。

If hot core rolling position strand exists liquid core, liquid core rate δ is greater than at 0 o'clock, determines and rolls according to following formula (11)Roller linear velocity v_r' and machine after drive line speed v₂'：

$\begin{array}{c}{v_r}^{\′}=\frac{H\·[b-\mathrm{\δ}(b-H+\mathrm{\δ}\·H)]}{[2R(1-\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2})+H\·(1-\mathrm{\ϵ})]\·b\·\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2}}\·v_0\·\mathrm{\λ},\\ {v_2}^{\′}=\frac{b-(b-H+\mathrm{\δ}\·H)\·\mathrm{\δ}}{(1-\mathrm{\ϵ})\·b}\·v_0\·k\end{array}---\left(11\right)$

In above formula, ε represents the reduction ratio of rolling, the % of unit, and reduction ratio ε is preferably more than or equals ${{\mathrm{\ϵ}}_{\min }}^{\′}=\max [({\mathrm{\ϵ}}_v+{\mathrm{\ϵ}}_l+\mathrm{\δ}),\frac{\mathrm{\μ}\·S}{H}].$

Below by concrete instance, hot core milling method of the present invention is described further.

Taking conticaster crystallizer liquid level as reference point, once cut anterior horizontal segment near casting at the strand of slab casterBase solidification end position for example arranges a roller mill on hot core rolling position S=30m, and the working roll radius of milling train is R=550mm, implements to set the rolling of drafts Δ H to continuous casting billet.

For the ease of relatively, in table 3 below, respectively taking four kinds of steel as example, lift with the parameters that wherein every kind of steel is correspondingExample is in table 3.

In each example, thickness of strand is H=250mm before rolling, calculate while setting drafts Δ H, according to table 1, table 2Data are carried out interpolation calculation, obtain solidification shrinkage rate ε_VWith linear shrinkage ε_l. In each example, before rolling, continuous casting billet width is b=1800mm, gets respectively speed correction factor λ=1, k=1, and while calculating after roll linear velocity and machine drive line speed, conticasterCasting speed is all set as v₀=1.0m/min. Calculate the minimum start rolling temperature T of casting billet surface_{R_min}Time, A_r3Value adopt experience public affairsFormula A_r3=910-310C-80Mn-20Cu-15Cr-55Ni-80Mo+0.35 (h-8) calculates that (in formula, h is that after rolling, product is thickDegree).

Table 3.

Claims (7)

1. the hot core milling method of continuous casting, is characterized in that, once cuts anterior horizontal segment near strand at casting blank of continuous casting machineSolidification end position arranges roller mill, and in described milling train position, casting blank surface temperature is greater than minimum start rolling temperature T_{R_min}ConditionUnder, obtain the liquid core rate δ of hot core rolling position place strand and judge whether this liquid core rate δ is 0, if liquid core rate δ is 0, to rollSpeed v processed_rStrand is carried out to drafts and be more than or equal to minimum drafts Δ H_minOnline hot core rolling;

Minimum drafts Δ H_min＝max[H·(ε_v+ε_l)，μ·S]，

Wherein, H is the slab thickness at inlet of rolling mill place, and unit is mm; ε_VFor solidification shrinkage rate, the % of unit; ε_lFor linear contractionRate, the % of unit; S is the distance of conticaster crystallizer liquid level to described milling train position, the m of unit; μ is light reduction ratio, spanBe 0.03～0.14%.

2. the hot core milling method of continuous casting as claimed in claim 1, is characterized in that, minimum start rolling temperature T_{R_min}＝A_r3-40℃，

Wherein, A_r3That strand steel grade starts to separate out ferritic critical-temperature line when cooling in austenite.

3. the hot core milling method of continuous casting as claimed in claim 1, is characterized in that, if liquid core rate δ is greater than 0, and described milling trainStrand is carried out to drafts and be more than or equal to minimum drafts Δ H_min' rolling, minimum drafts Δ H_min'＝max[H·(ε_v+ε_l+δ)，μ·S]，

Wherein, H is the slab thickness at inlet of rolling mill place, and unit is mm; ε_VFor solidification shrinkage rate, the % of unit; ε_lFor linear contractionRate, the % of unit; δ is milling train position liquid core rate, the % of unit; S is the distance of conticaster crystallizer liquid level to described milling train position, singlePosition m; μ is light reduction ratio, and span is 0.03～0.14%.

4. the hot core milling method of continuous casting as claimed in claim 1, is characterized in that the mill speed of described milling train

Wherein, H represents the slab thickness at inlet of rolling mill place, and unit is mm; R represents roller radius, and unit is mm; ε represents rollingReduction ratio, the % of unit; v₀Represent casting speed, unit is m/min; λ is speed of rolls correction factor, and span is 0.9～1.1。

5. the hot core milling method of continuous casting as claimed in claim 4, is characterized in that, the rear portion rollgang of described milling train is with lineSpeed v₂Carry the linear velocity of described milling train rear portion rollgang $v_2=\frac{1}{1-\mathrm{\ϵ}}\·v_0\·k,$

Wherein, speed correction factor after the machine that k is milling train, span is 0.9～1.1.

6. the hot core milling method of the continuous casting as described in claim 1 or 4, is characterized in that, if liquid core rate δ is greater than 0, and described milling trainWith mill speed v_r' strand is rolled to mill speed ${v_r}^{\′}=\frac{H\·\[b-\mathrm{\δ}(b-H+\mathrm{\δ}\·H)\]}{\[2R(1-\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2})+H\·(1-\mathrm{\ϵ})\]\·b\·\cos \frac{\sqrt{\mathrm{\ϵ}\·H/R}}{2}}\·v_0\·\mathrm{\λ},$

Wherein, H represents the slab thickness at inlet of rolling mill place, and unit is mm; B represents strand width, and unit is mm; δ represents milling trainPosition liquid core rate, the % of unit; R represents roller radius, and unit is mm; ε represents the reduction ratio of rolling, the % of unit; v₀Represent throwingSpeed, unit is m/min; λ is speed of rolls correction factor, and span is 0.9～1.1.

7. the hot core milling method of continuous casting as claimed in claim 6, is characterized in that, the rear portion rollgang of described milling train is with lineSpeed v₂' carry the linear velocity of described milling train rear portion rollgang ${v_2}^{\′}=\frac{b-(b-H+\mathrm{\δ}\·H)\·\mathrm{\δ}}{(1-\mathrm{\ϵ})\·b}\·v_0\·k,$

Wherein, speed correction factor after the machine that k is milling train, span is 0.9～1.1.