CN104492823B - A kind of method obtaining constant elongation percentage under acceleration and deceleration state - Google Patents

Abstract

The present invention provides a kind of method obtaining constant elongation percentage under acceleration and deceleration state, gather strip steel at entry speed and outlet strip speed respectively, variable-length is set and calculates the cycle, calculate elongation percentage actual value, compare with elongation percentage setting value, obtain elongation percentage difference, with the product of the elongation percentage self-adaptative adjustment factor as the input value of PI controller, output roll-force controls ring and the additional controlled quentity controlled variable of tension force control ring, superimposed with the roll-force self-adaptative adjustment factor, obtains final roll-force adjustment amount.The present invention, by arranging the elongation percentage length computation cycle in friction speed section, solves strip steel slippage problems during acceleration and deceleration；By the 3 of actual speed evolution related operations, carry out the feedforward and accelerate the adjustment of elongation percentage fluctuation during acceleration and deceleration；By the expection roll-force error dynamics correction of actual roll-force and elongation percentage with consider thickness, width and elongation percentage relation, adaptive factor is set to solve control accuracy and the stability of elongation percentage during acceleration and deceleration.

Description

A kind of method obtaining constant elongation percentage under acceleration and deceleration state

Technical field

The present invention relates to cold-strip steel planisher production field, particularly relate to obtain constant elongation percentage under a kind of acceleration and deceleration state Method.

Background technology

In annealing operation, strip steel is due to recrystallization, creates strain-aging, there will be yield point elongation in following process, this Strip steel after annealing almost goes completely into soft state, is not suitable for processing；As long as giving slightly slight punch process, band Steel surface will produce elongation strain and irregular skid wire.Therefore the cold-strip steel after annealing is carried out slight smooth process, To eliminate yield point elongation, to improve tensile strength so that it is there is good strip steel mechanical performance, improve belt plate shape, adjust strip steel Surface roughness, it is thus achieved that satisfactory coil of strip.

In Cold-Rolled Strip Temper Mill, elongation percentage is important technic index, for obtaining constant elongation percentage, by regulating roll-force and can open Power reaches the purpose that specific elongation steadily controls.But under acceleration and deceleration state, the speed of skin pass mill group, tension force, roll-force, prolong Stretching rate, leveling precision adhesion amount etc., all in labile state, therefore occurs that elongation percentage fluctuation is excessive so that smooth section of acceleration and deceleration band Steel Properties does not meets technological requirement.

Summary of the invention

The technical problem to be solved in the present invention is: provide a kind of method obtaining constant elongation percentage under acceleration and deceleration state so that plus-minus The smooth section strip steel performance of speed meets technological requirement.

The present invention solves that the technical scheme that above-mentioned technical problem is taked is: under a kind of acceleration and deceleration state, obtain constant elongation percentage Method, it is characterised in that: it comprises the steps:

S1, respectively collection strip steel at entry speed and outlet strip speed, arrange variable-length and calculate the cycle, calculate elongation percentage actual Value；

On the basis of strip steel at entry speed or outlet strip speed, obtain variable-length according to its scope and calculate the cycle, and calculating is prolonged Stretch rate；Measure the periodic quantity that roller rotation girth has reached and friction speed section is arranged, initiate as next elongation percentage measured value Point, i.e. measures roller girth and often rotates certain distance elongation percentage actual value of calculating, and this certain distance has with friction speed section Close；

S2, will extend over rate actual value and compare with elongation percentage setting value, obtain elongation percentage difference, with the elongation percentage self-adaptative adjustment factor gain_aptProduct as the input value of PI controller, output roll-force controls ring and tension force controls the additional controlled quentity controlled variable of ring；Wherein Elongation percentage self-adaptative adjustment factor gain_aptComputing formula as follows:

$\mathrm{gai}{n}_{\mathrm{apt}}\left(n\right)=\frac{{\mathrm{Width}}_{\mathrm{set}}\×{\mathrm{Thk}}_{\mathrm{set}}}{{\mathrm{Width}}_{\max }\×{\mathrm{Thk}}_{\max }}\×\∫({\mathrm{FR}}_{\mathrm{act}}-100\×\mathrm{ELC}\×\∫{\mathrm{gain}}_{\mathrm{apt}}(n-1))$

In formula, Width_setFor setting strip width, Thk_setSet belt steel thickness, FR_actFor roll-force actual value, ELC is for extending Rate actual value, Width_maxFor strip width maximum, Thk_maxFor belt steel thickness maximum, n is iterative times, n=1,2,3 ...；

S3, the additional controlled quentity controlled variable that roll-force controls ring are superimposed with the roll-force self-adaptative adjustment factor, obtain final roll-force Adjustment amount, is adjusted roll-force；Wherein the computing formula of roll-force adjustment amount is as follows:

${\mathrm{\ΔFR}}_{\mathrm{corr}}=\left({\mathrm{FR}}_{\mathrm{cal}}\right)\×\frac{\sqrt[3]{V_{\mathrm{act}}}-\sqrt[3]{V_{\mathrm{thread}}}}{\sqrt[3]{V_{\max }}}+\mathrm{\ΔFR}$

In formula, △ FR_corrControl the final adjustment amount of ring for roll-force, △ FR is the additional controlled quentity controlled variable that roll-force controls ring, FR_cal For demarcating roll-force, V_actFor the actual strip speed of planisher unit, V_threadCreep setting speed for planisher unit, V_maxFor smooth Machine unit maximal rate.

By such scheme, V_maxFor planisher unit maximal rate, Cir_RollFor measuring roller girth, on the basis of strip steel at entry speed,

If it is less than or equal to n₁V_max, then measure roller girth and often rotate m₁Cir_RollAn elongation percentage actual value is calculated during distance；

If it is more than n₁V_maxAnd less than or equal to n₂V_max, then measure roller girth and often rotate m₂Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₂V_maxAnd less than or equal to n₃V_max, then measure roller girth and often rotate m₃Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₃V_maxAnd less than or equal to n₄V_max, then measure roller girth and often rotate m₄Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₄V_max, then measure roller girth and often rotate m₅Cir_RollAn elongation percentage actual value is calculated during distance；

Wherein 0 < n₁<n₂<n₃<n₄< 1,0 < m₁<m₂<m₃<m₄<m₅<1。

By such scheme, described elongation percentage actual value is calculated by below equation:

$\mathrm{ELC}=\frac{{\mathrm{Len}}_{\mathrm{exit}}-{\mathrm{Len}}_{\mathrm{entry}}}{{\mathrm{Len}}_{\mathrm{entry}}}\&times;100\%$

In formula, ELC is elongation percentage actual value, Len_exitFor the strip length passed through in the planisher exporting unit time, Len_entryFor The strip length that planisher passed through in the entrance unit time,

Wherein Len_entry=Cir_{Roll enters}*Δt*V_{Roll enters}, Cir_{Roll enters}For the girth of entrance guide roller, V_{Roll enters}Turning for entrance guide roller Speed, Δ t is the unit time；Len_exitIn like manner obtain.

The invention have the benefit that by arranging the different elongation percentage length computation cycles in friction speed section, solve plus-minus Strip steel slippage problems during speed；By the 3 of actual speed evolution related operations, carry out the feedforward and accelerate acceleration and deceleration process The adjustment of middle elongation percentage fluctuation；By actual roll-force and elongation percentage expection roll-force error dynamics correction and consideration thickness, width With elongation percentage relation, adaptive factor is set to solve control accuracy and the stability of elongation percentage during acceleration and deceleration；Final realization The effect of constant elongation percentage is obtained under acceleration and deceleration state.

Accompanying drawing explanation

Fig. 1 is the control principle drawing of one embodiment of the invention.

Fig. 2 is the elongation percentage length computation periodogram that friction speed section is arranged.

Fig. 3 is the application principle figure of one embodiment of the invention.

Fig. 4 is the test effect figure of one embodiment of the invention.

Detailed description of the invention

Below in conjunction with instantiation and accompanying drawing, the present invention will be further described.

Fig. 1 is the control principle drawing of one embodiment of the invention, and the present embodiment provides and obtains constant elongation percentage under a kind of acceleration and deceleration state Method, comprise the steps:

S1, respectively collection strip steel at entry speed and outlet strip speed, arrange variable-length and calculate the cycle, calculate elongation percentage actual Value；

On the basis of strip steel at entry speed or outlet strip speed, obtain variable-length according to its scope and calculate the cycle, and calculating is prolonged Stretch rate；Measure the periodic quantity that roller rotation girth has reached and friction speed section is arranged, initiate as next elongation percentage measured value Point.I.e. measure roller girth and often rotate certain distance (this certain distance is relevant with friction speed section) elongation percentage of calculating in fact Actual value；

Concrete, make V_maxFor planisher unit maximal rate, Cir_RollFor measuring roller girth, can be with strip steel at entry speed as base Standard,

If it is less than or equal to n₁V_max, then measure roller girth and often rotate m₁Cir_RollAn elongation percentage actual value is calculated during distance；

If it is more than n₁V_maxAnd less than or equal to n₂V_max, then measure roller girth and often rotate m₂Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₂V_maxAnd less than or equal to n₃V_max, then measure roller girth and often rotate m₃Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₃V_maxAnd less than or equal to n₄V_max, then measure roller girth and often rotate m₄Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₄V_max, then measure roller girth and often rotate m₅Cir_RollAn elongation percentage actual value is calculated during distance；

Wherein 0 < n₁<n₂<n₃<n₄< 1,0 < m₁<m₂<m₃<m₄<m₅<1。

In the present embodiment, n₁=0.05, n₂=0.15, n₃=0.35, n₄=0.65；m₁=0.1, m₂=0.12, m₃=0.15, m₄=0.3, m₅=0.5.

S2, will extend over rate actual value and compare with elongation percentage setting value, obtain elongation percentage difference, with the elongation percentage self-adaptative adjustment factor gain_aptProduct as the input value of PI controller, output roll-force controls ring and tension force controls the additional controlled quentity controlled variable of ring；Wherein Elongation percentage self-adaptative adjustment factor gain_aptComputing formula as follows:

$\mathrm{gai}{n}_{\mathrm{apt}}\left(n\right)=\frac{{\mathrm{Width}}_{\mathrm{set}}\&times;{\mathrm{Thk}}_{\mathrm{set}}}{{\mathrm{Width}}_{\max }\&times;{\mathrm{Thk}}_{\max }}\&times;\&Integral;({\mathrm{FR}}_{\mathrm{act}}-100\&times;\mathrm{ELC}\&times;\&Integral;{\mathrm{gain}}_{\mathrm{apt}}(n-1))$

In formula, Width_setFor setting strip width, Thk_setSet belt steel thickness, FR_actFor roll-force actual value, ELC is for extending Rate actual value, Width_maxFor strip width maximum, Thk_maxFor belt steel thickness maximum, n is iterative times, n=1,2,3 ....

S3, the additional controlled quentity controlled variable that roll-force controls ring are superimposed with the roll-force self-adaptative adjustment factor, obtain final roll-force Adjustment amount, is adjusted roll-force；Wherein the computing formula of roll-force adjustment amount is as follows:

${\mathrm{\&Delta;FR}}_{\mathrm{corr}}=\left({\mathrm{FR}}_{\mathrm{cal}}\right)\&times;\frac{\sqrt[3]{V_{\mathrm{act}}}-\sqrt[3]{V_{\mathrm{thread}}}}{\sqrt[3]{V_{\max }}}+\mathrm{\&Delta;FR}$

In formula, △ FR_corrControl the final adjustment amount of ring for roll-force, △ FR is the additional controlled quentity controlled variable that roll-force controls ring, FR_cal For demarcating roll-force, V_actFor the actual strip speed of planisher unit, V_threadCreep setting speed for planisher unit, V_maxIt is flat Complete machine unit maximal rate.

Below in conjunction with principle, the present invention is elaborated.

One, planisher elongation percentage computational methods

Skin pass rolling is production prime sheet, guarantees last one critical process of strip steel end product quality, and it is for improving product matter Amount, panel shape, thin plate is made to have suitable mechanical property according to user's request and apparent condition plays an important role.Cold Offseting elongation percentage in complete machine is important technic index, for obtaining constant elongation percentage, can be reached by regulation roll-force or tension force The purpose that specific elongation steadily controls.

Elongation percentage conventionally calculation formula is

$\mathrm{ELC}=\frac{V_{\mathrm{exit}}-V_{\mathrm{entry}}}{V_{\mathrm{entry}}}\&times;100\%$ (formula 1-1)

In formula, V_exitPlanisher outlet strip speed m/s, V_entryPlanisher strip steel at entry speed m/s, ELC is that elongation percentage is actual Value.

Due to the smooth secondary deformation carrying out light reduction for strip steel, length direction extends negligible, according to constancy of volume principle, Elongation percentage computing formula also can be exchanged into:

$\mathrm{ELC}=\frac{{\mathrm{Len}}_{\mathrm{exit}}-{\mathrm{Len}}_{\mathrm{entry}}}{{\mathrm{Len}}_{\mathrm{entry}}}\&times;100\%$ (formula 1-2)

In formula, ELC is elongation percentage actual value, Len_exitFor the strip length passed through in the planisher exporting unit time, Len_entryFor The strip length that planisher passed through in the entrance unit time,

Wherein Len_entry=Cir_{Roll enters}*Δt*V_{Roll enters}, Cir_{Roll enters}For the girth of entrance guide roller, V_{Roll enters}Turning for entrance guide roller Speed, Δ t is the unit time；Len_exitIn like manner obtain.The present invention preferably this mode calculates elongation percentage actual value.

Two, planisher elongation control principle

Elongation control model can be controlled by roll-force or be controlled by tension force or roll-force adds tension force control.

According to the size of belt steel thickness, the weight that distribution roll-force controls and tension force controls, when often supplied materials thickness is bigger, use Roll-force control model, uses tension control mode or roll-force to add tension control mode time relatively thin；Actual control principle is: Will extend over rate actual value and compare difference with target setting value, this difference is sent to elongation control device.Elongation control device is according to adopting Control model determine tension value size before and after actual additional roll-force or planisher, revise pressure rolling force setup value or Revise the setting tension value before and after planisher.Outside finally by tension force Controlling model before and after pressure roll-force Controlling model or planisher The size of ring regulation elongation percentage.

Three, constant elongation percentage method is obtained under acceleration and deceleration state

Under acceleration and deceleration state, the speed of skin pass mill group, tension force, roll-force, elongation percentage, leveling precision adhesion amount etc. is not all in Steady statue, therefore occurs that elongation percentage fluctuation is excessive so that the smooth section strip steel of acceleration and deceleration does not meets technological requirement.

By groping of the debugging process of elongation percentage in certain planisher Practical Project, invent from three angles to solve acceleration and deceleration The fluctuation problem method of elongation percentage in journey, it was demonstrated that effect is good.Elongation percentage detection is by arranging not in friction speed section In the same elongation percentage length computation cycle, solve strip steel slippage problems during acceleration and deceleration；By the 3 of actual speed evolution phases Close computing, carry out the feedforward and accelerate the adjustment of elongation percentage fluctuation during acceleration and deceleration；Expected with elongation percentage by actual roll-force Roll-force error dynamics correction and consider thickness, width and elongation percentage relation, arranges adaptive factor to during solving acceleration and deceleration The control accuracy of elongation percentage and stability.

(1) process of elongation percentage measured value under acceleration and deceleration

The elongation percentage of planisher is typically measured or two of inlet/outlet guide roller by two laser velocimeters of planisher inlet/outlet Encoder is measured.Laser velocimeter is vertical with belt steel surface, directly detects the linear velocity of strip steel.Encoder is separately mounted to machine On the shaft centre line of frame inlet/outlet guide roller, by the linear velocity of guide roller rotating speed conversion inlet/outlet strip steel.Laser velocimeter precision Height, and it is not skidded by strip steel acceleration and deceleration and is affected, and is the first-selection of planisher elongation percentage instrumentation configuration.But laser velocimeter Instrument is expensive, it is often necessary to safeguard, uses encoder detection elongation percentage cost performance higher for medium-sized and small enterprises.

Using encoder to measure elongation percentage precision and be less than laser velocimeter, skidding during these external acceleration and deceleration influences whether detection Actual strip speed.According to constancy of volume principle, and the extension of width is negligible after smooth, encoder speed is surveyed Value is converted into length value, then uses elongation percentage length computation formula (1-2), calculates actual elongation percentage.

Owing to encoder is arranged on inlet/outlet guide roller, it is output as guide roller actual speed, in actual control, and sampling week Phase is 1.6ms, takes the guide roller rotating speed meansigma methods in 4 sampling periods as guide roller actual speed, is then directed to roller actual Rotating speed is scaled actual strip length.

For the slippage problems avoiding velocity variations to cause, improving elongation control precision, the present invention provides a kind of addition method of measuring to use In the measurement of elongation percentage, i.e. eliminate, by the length computation cycle, the impact that encoder measurement accuracy is low.Simultaneously because different bands Steel speed slippery conditions is different, measures roller in the detection of FM458 controller and rotates girth and have reached and friction speed section is arranged prolongs Stretch rate length computation periodic quantity, as next elongation percentage measured value starting point, as shown in Figure 2.

(2) the feed forward open loop regulation of elongation percentage controller output under acceleration and deceleration.

Considering that velocity variations can cause coefficient of friction to change, acceleration mode elongation percentage actual value when not being modified reduces, deceleration shape State elongation percentage actual value when not being modified increases.By repeatedly testing, invent a kind of 3 evolutions relevant to actual speed Related operation, carries out the feedforward and adjusts elongation percentage fluctuation during acceleration and deceleration in advance.

Owing to feedforward control accuracy is limited, therefore when carrying out the feedforward, be only added to roll-force by feedforward preconditioning amount Control ring.

(3) the feedback closed loop Automatic adjusument of elongation percentage controller under acceleration and deceleration.

Detection and feed forward open loop regulation can pre-adjust elongation percentage when acceleration and deceleration so that it is fluctuate near setting value, but at plus-minus Elongation percentage constant control to be reached under Su, in addition it is also necessary to according to actual roll-force, preset roll-force, width and thickness etc. to elongation percentage control Device processed dynamically adjusts, it is achieved self-adapting closed loop controls.

Consider thickness and width and elongation percentage relation, and change of external conditions can cause elongation percentage to change, and then cause roll-force Change, according to actual roll-force with elongation percentage expection roll-force error as the elongation percentage self-adaptative adjustment factor.Elongation percentage self adaptation The product of Dynamic gene and elongation percentage difference, as elongation control object, iterates adjustment during acceleration and deceleration repeatedly.

(4) for being embodied as by the elongation control algorithm of design under acceleration and deceleration state, FM458 has carried out programming, Programming uses CFC to complete, programme-control block diagram such as Fig. 3.Five clock cycle as elongation control unit F M458 It is respectively set to 1.6ms, 6.4ms, 12.8ms, 51.2ms, 204.8ms, WINCC (the process prison run in man machine interface Viewing system) show for practical production status, process data acquisition system iba is used for gathering, Real time displaying and analysis carry out automatic control The analog and digital signal of system processed and control effect.

Four, actual verification and interpretation of result

The acceleration and deceleration elongation control algorithm of the present invention is tested in actual planisher, and this planisher elongation control is added and subtracted Guarantee value under speed state is ± 0.15%.For checking effectiveness of the invention, have employed iba data collecting system, intercept and survey During examination, real data is analyzed, as shown in Figure 4.

From data and curves shown in Fig. 4 it can be seen that use the acceleration and deceleration elongation control algorithm of the present invention, there is higher control Precision, when elongation percentage setting value is 1%, actual elongation control 0.924%～1.075% (accuracy rating-0.076%～ + 0.075%), guarantee value requirement has been reached far away.This explanation controlling plan design be highly effective and also successfully.

Obtain constant elongation percentage method under the acceleration and deceleration state that the present invention proposes and compared with prior art have the effect that (1) adds Lower elongation percentage control accuracy of slowing down reaches-0.076%～+0.075%, has higher control accuracy, has reached guarantee value requirement and (protected Card value required precision ± 0.15%), the processing performance of smooth strip steel during improving acceleration and deceleration；(2) present invention realizes simply, can It is generalized to the electrical control of this type skin pass mill group elongation control system；(3) elongation percentage detection is by friction speed section The different elongation percentage length superposition cycles is set, solves strip steel slippage problems during acceleration and deceleration；(4) by repeatedly testing, adopt Carry out the feedforward with a kind of 3 evolution related operations relevant to actual speed, control ring in advance to acceleration and deceleration by roll-force During elongation percentage fluctuation adjust, improve accelerate time elongation percentage actual value less than normal, elongation percentage actual value problem bigger than normal during deceleration.(5) According to actual roll-force with elongation percentage expection roll-force error as the self-adaptative adjustment factor, the self-adaptative adjustment factor is inclined with elongation percentage The product of difference, as elongation control object, iterates adjustment during acceleration and deceleration repeatedly, solves elongation percentage during acceleration and deceleration Control accuracy and stability problem.

Above example is merely to illustrate design philosophy and the feature of the present invention, its object is to make those skilled in the art's energy Solution present disclosure much of that is also implemented according to this, and protection scope of the present invention is not limited to above-described embodiment.So, all according to this Equivalent variations that bright disclosed principle, mentality of designing are made or modification, all within protection scope of the present invention.

Claims (1)

1. the method obtaining constant elongation percentage under an acceleration and deceleration state, it is characterised in that: it comprises the steps:

S1, respectively collection strip steel at entry speed and outlet strip speed, arrange variable-length and calculate the cycle, calculate elongation percentage actual Value；

On the basis of strip steel at entry speed or outlet strip speed, obtain variable-length according to its scope and calculate the cycle, and calculating is prolonged Stretch rate；Measure the periodic quantity that roller rotation girth has reached and friction speed section is arranged, initiate as next elongation percentage measured value Point, i.e. measures roller girth and often rotates certain distance elongation percentage actual value of calculating, and this certain distance has with friction speed section Close；

S2, will extend over rate actual value and compare with elongation percentage setting value, obtain elongation percentage difference, with the elongation percentage self-adaptative adjustment factor gain_aptProduct as the input value of PI controller, output roll-force controls ring and tension force controls the additional controlled quentity controlled variable of ring；Wherein Elongation percentage self-adaptative adjustment factor gain_aptComputing formula as follows:

${\mathrm{gain}}_{apt}\left(n\right)=\frac{{\mathrm{Width}}_{set}\&times;{\mathrm{Thk}}_{set}}{{\mathrm{Width}}_{\max }\&times;{\mathrm{Thk}}_{\max }}\&times;\&Integral;({\mathrm{FR}}_{act}-100\&times;ELC\&times;\&Integral;{\mathrm{gain}}_{apt}(n-1\left)\right)$

In formula, Width_setFor setting strip width, Thk_setSet belt steel thickness, FR_actFor roll-force actual value, ELC is for extending Rate actual value, Width_maxFor strip width maximum, Thk_maxFor belt steel thickness maximum, n is iterative times, n=1,2,3 ...；

S3, the additional controlled quentity controlled variable that roll-force controls ring are superimposed with the roll-force self-adaptative adjustment factor, obtain final roll-force Adjustment amount, is adjusted roll-force；Wherein the computing formula of roll-force adjustment amount is as follows:

${\mathrm{\&Delta;FR}}_{corr}=\left({\mathrm{FR}}_{cal}\right)\&times;\frac{\sqrt[3]{V_{act}}-\sqrt[3]{V_{thread}}}{\sqrt[3]{V_{max}}}+\mathrm{\&Delta;}FR$

In formula, △ FR_corrControl the final adjustment amount of ring for roll-force, △ FR is the additional controlled quentity controlled variable that roll-force controls ring, FR_cal For demarcating roll-force, V_actFor the actual strip speed of planisher unit, V_threadCreep setting speed for planisher unit, V_maxIt is flat Complete machine unit maximal rate；

Make V_maxFor planisher unit maximal rate, Cir_RollFor measuring roller girth, on the basis of strip steel at entry speed,

If it is less than or equal to n₁V_max, then measure roller girth and often rotate m₁Cir_RollAn elongation percentage actual value is calculated during distance；

If it is more than n₁V_maxAnd less than or equal to n₂V_max, then measure roller girth and often rotate m₂Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₂V_maxAnd less than or equal to n₃V_max, then measure roller girth and often rotate m₃Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₃V_maxAnd less than or equal to n₄V_max, then measure roller girth and often rotate m₄Cir_RollAn elongation percentage is calculated during distance Actual value；

If it is more than n₄V_max, then measure roller girth and often rotate m₅Cir_RollAn elongation percentage actual value is calculated during distance；

Wherein 0 < n₁<n₂<n₃<n₄< 1,0 < m₁<m₂<m₃<m₄<m₅<1；

Described elongation percentage actual value is calculated by below equation:

$ELC=\frac{{\mathrm{Len}}_{exit}-{\mathrm{Len}}_{entry}}{{\mathrm{Len}}_{entry}}\&times;100\%$

In formula, ELC is elongation percentage actual value, Len_exitFor the strip length passed through in the planisher exporting unit time, Len_entryFor The strip length that planisher passed through in the entrance unit time,

Wherein Len_entry=Cir_{Roll enters}*Δt*V_{Roll enters}, Cir_{Roll enters}For the girth of entrance guide roller, V_{Roll enters}Turning for entrance guide roller Speed, Δ t is the unit time；Len_exitIn like manner obtain.