CN105312358A - Tension control method for cold-rolled strip steel in acid continuous rolling working procedure - Google Patents

Abstract

The invention relates to a tension control method for cold-rolled strip steel in the acid continuous rolling working procedure. According to the tension control method, a withdrawal and straightening machine frequency converter and a PLC are adopted for controlling tension of the strip steel on a withdrawal and straightening machine section, when a set value of the tension of the strip steel on the withdrawal and straightening machine section is larger than zero, positive tension control is adopted, when the set value of the tension of the strip steel on the withdrawal and straightening machine section is smaller than zero, negative tension control is adopted, positive or negative switch control over the tension of the strip steel on the withdrawal and straightening machine section is achieved, the tension of strip steel in a pickling bath is controlled by controlling the tension of the strip steel on the withdrawal and straightening machine section, the tension of the pickling bath is increased substantially, and the problems that due to an existing control mode, the surface of the strip steel is scratched, rectorites are replaced frequently, and loss is caused are solved.

Description

The tension control method of cold-strip steel in a kind of sour tandem rolling operation

Technical field

The tension force that the present invention relates to cold-strip steel technical field, particularly cold-strip steel controls, specifically the tension control method of cold-strip steel in a kind of sour tandem rolling operation.

Background technology

There is an important procedure to be pickling in cold rolling process, by the iron scale wash clean of this operation by band steel top layer, be beneficial to the deep processing of follow-up unit.In pickling unit or sour tandem rolling operation unit, band steel goes to toward first through withdrawal straightening machine entering descaling bath.By the effect of withdrawal straightening machine, not only dephosphorization is carried out to belt steel surface, but also band steel plate type is improved, be with steel to enter descaling bath subsequently and carry out pickling, to improve pickling effect.In strip pickling process, because descaling bath reaches rice up to a hundred, band steel is easy to form sagging arc in cell body, causes belt steel surface to occur to scratch phenomenon.Along with the accumulation of the friction between band steel and cell body, also affect the service life of holding in the palm stone bottom cell body, cause maintenance cost to rise.If change slightly not in time, cell body can be caused time serious worn out, and then produce seepage, seepage not only produces a large amount of acid mist, affects the person healthy, but also etching apparatus, make to be repaired by forced-stopping machine.To be that band steel is sagging in pickling section acid tank wipe schematic diagram with holder stone to Fig. 1 mutually, is provided with withdrawal straightening machine body 1, first tension roll assembly, withdrawal straightening machine surveys instrument 2, second tension roll assembly, descaling bath body 4, front and back pinch roll 4a, 4b, holder stone 4c, the 3rd tension roll assembly and acid tank and survey an instrument 6.According to the difference of descaling bath strip tension, the sagging radian of band steel is also different, keeps a principle with radian be with steel and formed and asks stone not grazing to be advisable.First tension roll assembly comprises the first jockey pulley 1a, the second jockey pulley 1b and the 3rd jockey pulley 1c, and the second tension roll assembly comprises the 4th jockey pulley 3a, the 5th jockey pulley 3b and the 6th jockey pulley 3c, and the 3rd tension roll assembly comprises the 7th jockey pulley 5a and the 8th jockey pulley 5b.

In order to reduce in descaling bath with steel sagging with holder stone even cell body produces the loss that grazing causes, need to control well better in descaling bath and be with the sagging radian of steel.Existing 2 kinds of traditional ameliorative way.The specification of first check strap steel and employing manual adjustment method, as 200710038532.4 patent applications of denomination of invention by " a kind of strip tension control method and device " are disclosed, because strip steel specification is partially thin, under equal tension, band steel is drawn more straight.Because of employing is manual mode, and the method can affect unit production capacity and operating efficiency, often can not meet production requirement.It two is specifications of not limit production band steel, adopts and improves descaling bath tension force setting method, amendment descaling bath tension force setting T ₄, reduce band steel sag as far as possible, the sagging minimum point A of band steel progressively raised, increase gap between A point and holder stone 4C, to reduce the loss that between band steel and holder stone, grazing causes.But because of withdrawal straightening machine special process requirement in pickling section, pickling section tension force improves will have influence on withdrawal straightening machine tension force T ₁if, pickling section tension force T ₄improve excessive, withdrawal straightening machine tension force T ₁" bearing " value will be become, and cannot carry out in prior art being with steel " to bear " detection of tension force, thus cannot implement to control, therefore pickling section tension force only can be improved about 5% ~ 10% by the method, often can not solve thick wide specification strip steel and the problem of holder stone grazing, can not production requirement be met.

As can be seen here, in above two kinds of improvement descaling baths, band steel radian method, although can improve the height of the sagging minimum point A of band steel, is all limited raising, need the specification of check strap steel and part to improve the tension force of band steel, often can not meet the requirement of this unit think gauge or specification expansion.

Summary of the invention

The object of this invention is to provide the tension control method of cold-strip steel in a kind of sour tandem rolling operation, this tension control method can detect based on tension leveler torque and convert strip tension to, the "positive" or "negative" of carrying out strip tension switches control, realize the significantly raising of descaling bath tension force, the loss problem that belt steel surface scratches and frequent replacing is held in the palm stone and produced caused in order to solve existing control mode.

For achieving the above object, the solution of the present invention is: the tension control method of cold-strip steel in a kind of sour tandem rolling operation, acid tandem rolling operation unit comprises withdrawal straightening machine, withdrawal straightening machine is surveyed Zhang Yi, descaling bath and descaling bath and surveyed Zhang Yi, described withdrawal straightening machine is arranged on the last procedure of descaling bath, this control method makes strip tension in descaling bath reach setting requirement by the strip tension of adjustment withdrawal straightening machine section, adopt withdrawal straightening machine frequency converter and the strip tension of PLC to withdrawal straightening machine section to control, described control method step is as follows:

(1) according to the band sectional area of steel and the relation of tension force, set up strip tension and withdrawal straightening machine section strip steel tension force static table in descaling bath, and described static table is stored in PLC internal memory, in the descaling bath stored in this static table, strip tension value is the setting value of strip tension in descaling bath;

(2) PLC is according to the specification treating pickled steel strip, obtain the sectional area being with steel, and by the static table described in search step (1), obtain strip tension value in withdrawal straightening machine section strip steel tension value and descaling bath, thus determine to make strip tension in descaling bath reach the withdrawal straightening machine section strip steel tension force setting value of its setting value;

(3) if the setting value of withdrawal straightening machine section strip steel tension force is greater than 0, then PLC receives withdrawal straightening machine and surveys a tension force analog value for instrument measurement, and digitized processing is the positive tension force actual value of band steel, positive for band steel tension force actual value and withdrawal straightening machine section strip steel tension force setting value are compared, export motor for withdrawal & straightening motor speed adjustment amount in withdrawal straightening machine frequency converter, the speed of withdrawal straightening machine frequency converter to motor for withdrawal & straightening machine adjusts, realize controlling the positive tension force of withdrawal straightening machine section strip steel, and enter step (6); If withdrawal straightening machine section strip steel tension force setting value is less than 0, then enter step (4);

(4) PLC receives the motor for withdrawal & straightening machine actual speed that withdrawal straightening machine frequency converter sends, and withdrawal straightening machine section strip steel tension force setting value is converted to the motor negative moment amplitude limit value of withdrawal straightening machine, the given value of current value of withdrawal straightening machine frequency converter is obtained according to the rotating speed of described motor negative moment amplitude limit value and motor, and send to withdrawal straightening machine frequency converter, amplitude limit control is carried out to motor for withdrawal & straightening machine moment, realizes controlling the negative tension force of withdrawal straightening machine section strip steel;

(5) PLC receives the motor for withdrawal & straightening machine moment values that withdrawal straightening machine frequency converter sends, and obtains the negative tension force actual value of withdrawal straightening machine section strip steel according to described motor for withdrawal & straightening machine moment values;

(6) compare the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value, if described deviation is less than the tension force deviate of setting, then complete the control of strip tension in a descaling bath; Otherwise, continue to adjust the tension force of withdrawal straightening machine section strip steel, until withdrawal straightening machine section strip steel tension force actual value and setting value deviation are less than the tension force deviate of setting, realize the control to the strip tension in descaling bath.

According to method of the present invention, in described step (1), in described descaling bath, strip tension and withdrawal straightening machine section strip steel tension force static table are:

According to method of the present invention, in described step (2), describedly determine that the method for withdrawal straightening machine section strip steel tension force setting value is:

$T_2={\left(\frac{\mathrm{Bg}\left(1\right)}{\mathrm{Bg}\left(2\right)}\right)}^{\frac{2}{3}}\×\mathrm{Bg}\left(2\right)$

$T_3={\left(\frac{\mathrm{Bg}\left(1\right)}{\mathrm{Bg}\left(2\right)}\right)}^{\frac{1}{3}}\×\mathrm{Bg}\left(2\right)$

T ₄＝Bg(2)

T ₁＝Bg(1)-Bg(2)-(T ₂+T ₃)×0.95

Wherein, Bg (1) is the withdrawal straightening machine section strip steel tension value that search static table obtains, strip tension value in the descaling bath that Bg (2) search static table obtains, T ₁for withdrawal straightening machine section strip steel tension force setting value, T ₂be the strip tension setting value between the 3rd jockey pulley and the 4th jockey pulley, T ₃be the tension force setting value between the 4th jockey pulley and the 5th jockey pulley, T ₄for strip tension setting value in acid tank.

According to method of the present invention, in described step (4), by the method that withdrawal straightening machine section strip steel tension force setting value converts motor for withdrawal & straightening machine negative moment amplitude limit value to be:

Wherein, M is negative moment amplitude limit calculated value, and D is roller footpath, and Gr is gear-box gear ratio, T ₁for withdrawal straightening machine section strip steel tension force setting value

According to method of the present invention, in described step (4), the given value of current value of withdrawal straightening machine frequency converter is:

I _{spc_min}＝-I _q

Wherein, I _{spc_min}the amplitude limit setting value of withdrawal straightening machine inverter current controller, I _qthe torque current value of motor for withdrawal & straightening machine, I _{withdrawal straightening machine}for withdrawal straightening machine rated current, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, n is the actual speed of motor for withdrawal & straightening machine.

According to method of the present invention, in described step (5), the method obtaining negative tension force actual value is:

I ₁＝I ₃-I ₂

$I_2=\frac{\mathrm{dn}}{\mathrm{dt}}\×C_1$

$T_{1\mathrm{act}}=-\frac{I_1}{D}$

Wherein: T _1actfor negative tension force actual value, C ₁for moment of accelerating conversion coefficient, J _{withdrawal straightening machine}for withdrawal straightening machine rotary inertia, D is roller footpath, and Gr is gear-box gear ratio, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, N _{withdrawal straightening machine}for the rated speed of motor for withdrawal & straightening machine, for withdrawal straightening machine accekeration, I ₁for withdrawal straightening machine section strip steel sets up torque current needed for tension force, I ₂for withdrawal straightening machine moment of accelerating electric current, I ₃for motor for withdrawal & straightening machine actual measurement torque current.

According to method of the present invention, in described step (6), the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value is:

$\mathrm{\ΔT}=\frac{|T_1-T_{\mathrm{act}}|}{T_1}$

Wherein, Δ T is the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value; T ₁for the setting value of withdrawal straightening machine section strip steel tension force; T _actfor withdrawal straightening machine section strip steel tension force actual value, when negative tension force controls, T _actequal negative tension force actual value, when positive tension force controls, T _actequal positive tension force actual value.

According to method of the present invention, in described step (3), withdrawal straightening machine being surveyed the method that tension force analog value that Zhang Yi obtains is converted to positive tension force actual value is:

$T_{2\mathrm{act}}=\frac{F_R}{80}\×(\frac{F}{16}-200)$

Wherein, T _2actfor positive tension force actual value, F _ruse by tensiometer the rated value of pressure head, the tension force analog value of F measured by tensiometer.

According to method of the present invention, in described step (3), to the control adoption rate integration control mode of the positive tension force of band steel.

The beneficial effect that the present invention reaches: 1) control method of the present invention is novel, the place needing to carry out negative tension force control can be widely used in, pickling section strip steel surface quality can not only be improved, and the consumption of holder stone can also be reduced, thering is provided technological means for improving strip surface quality, meeting and producing and technological requirement.

2) the negative tension force that the present invention is based on tension leveler torque controls, and need not separately increase the extras bearing tension force etc. for measuring tape steel newly, therefore cost is low, can save cost for enterprise.

3) the present invention is applicable to the place adopting vector converter, strong adaptability, may extend to the production line adopting vector converter device, has wide promotional value.

4) control method of the present invention can reduce product degradation losses, reduces holder stone renewal cost, thus improves Business Economic Benefit.

Accompanying drawing explanation

Fig. 1 is band steel acid tandem rolling operation unit;

Fig. 2 is control principle drawing of the present invention;

Fig. 3 is control method flow chart of the present invention.

Detailed description of the invention

Below in conjunction with accompanying drawing, the present invention is further detailed explanation.

As Fig. 1, acid tandem rolling operation unit comprises withdrawal straightening machine body 1, first tension roll assembly 1a, 1b, 1c, a withdrawal straightening machine survey instrument 2, second tension roll assembly 3a, 3b, 3c, an instrument 6 surveyed by descaling bath body 4, front and back pinch roll 4a, 4b, holder stone 4c, the 3rd tension roll assembly 5a, 5b and descaling bath.Withdrawal straightening machine surveys an instrument 2 for measuring the strip tension value of withdrawal straightening machine section, and descaling bath body 4 is for carrying out pickling to band steel, and the band steel that each tension roll assembly is used for withdrawal straightening machine and descaling bath produces tension force.Control method of the present invention makes strip tension in descaling bath reach setting requirement by the strip tension of adjustment withdrawal straightening machine section, adopts withdrawal straightening machine frequency converter and the strip tension of PLC to withdrawal straightening machine section to control.Introduce the specific embodiment of control method of the present invention below in detail.

As Fig. 2, the present invention arranges indirect tension measuring appliance A5, negative tension controller A4, directly tonometry device A7, positive tension controller A6, selector A3, given tension device A1 and tension force setting adapter A2 in PLC.Wherein, tension force setting adapter, rule of thumb pre-determines the strip tension value at descaling bath and withdrawal straightening machine place, and is stored in PLC; Given tension device, according to the output valve of tension force setting adapter, calculates the tension force between withdrawal straightening machine tension force setting value and tension roll assembly; Selector, according to the output valve of given tension device, carries out logical process, selects to drop into negative tension controller, or positive tension controller; Direct tonometry device, carries out digitized processing to withdrawal straightening machine tensiometer signal, converts the tension force that band steel is corresponding to; Positive tension controller, puts into operation according to selector, obtains " just " given tension value that given tension device exports, the output valve of more direct tonometry device, adoption rate integration control, output speed adjustment amount, to withdrawal straightening machine frequency converter, realizes direct tension control; Indirect tension measuring appliance, obtains the moment values of withdrawal straightening machine frequency converter and converts the tension force being with steel to; Negative tension controller, puts into operation according to selector, obtains " bearing " given tension value that given tension device exports, converts negative moment amplitude limit value to, send to withdrawal straightening machine frequency converter to carry out moment closed-loop control, indirectly realizes negative tension force controlling functions; Withdrawal straightening machine frequency converter, sends tension leveler torque value, rotating speed periodically in real time, and receives motor for withdrawal & straightening machine speed preset value, negative moment amplitude limit value.

As shown in Figure 3, control method of the present invention comprises the steps:

(1) tension force setting adapter is according to the band sectional area of steel and the relation of tension force, and set up strip tension and withdrawal straightening machine section strip steel tension force static table in descaling bath, and be stored in PLC internal memory by described static table, the static table of foundation is as follows:

Total tension force with steel and its cross-sectional area are substantially proportional, and total tension force of band steel is multiplied by cross-sectional area by unit tension and obtains, and the tension force of band steel unit cross-sectional area is unit tension.

(2) given tension device is according to being about to the strip steel specification entering sour tandem rolling operation unit, calculate the sectional area of band steel, tension force static table in search step (1), determine strip tension Bg (2) in withdrawal straightening machine section strip steel tension force Bg (1) and descaling bath, and obtain withdrawal straightening machine section strip steel tension force setting value, detailed process is as follows:

$T_2={\left(\frac{\mathrm{Bg}\left(1\right)}{\mathrm{Bg}\left(2\right)}\right)}^{\frac{2}{3}}\×\mathrm{Bg}\left(2\right)$

$T_3={\left(\frac{\mathrm{Bg}\left(1\right)}{\mathrm{Bg}\left(2\right)}\right)}^{\frac{1}{3}}\×\mathrm{Bg}\left(2\right)$

T ₄＝Bg(2)

T ₁＝Bg(1)-Bg(2)-(T ₂+T ₃)×0.95

Wherein, Bg (1) is the withdrawal straightening machine section strip steel tension value that obtains of search static table, and Bg (2) searches for strip tension value in descaling bath that static table obtains, T ₁for withdrawal straightening machine section strip steel tension force setting value, T ₂for the strip tension setting value between withdrawal straightening machine the 3rd jockey pulley 1c and the 4th jockey pulley 3a, T ₃be the strip tension setting value between the 4th jockey pulley 3a and the 5th jockey pulley 3b, T ₄for strip tension setting value in acid tank.

(3) selector carries out Logic judgment to the output valve of given tension device, judges that the withdrawal straightening machine section strip steel tension force setting value that given tension device exports is greater than 0, is still less than 0.

(4) if the withdrawal straightening machine section strip steel tension force setting value that given tension device exports is less than 0, then selector selects negative tension controller to carry out negative tension force control to band steel, realizes strip tension in descaling bath and improves the function of more than 10%.Negative tension force control procedure is as follows:

1) negative tension controller obtains withdrawal straightening machine section strip steel tension force setting value and the withdrawal straightening machine tachometer value of withdrawal straightening machine frequency converter transmission, withdrawal straightening machine section strip steel tension force setting value is converted to the motor negative moment amplitude limit value of withdrawal straightening machine by negative tension controller, the given value of current value of withdrawal straightening machine frequency converter is obtained according to the rotating speed of described motor negative moment amplitude limit value and motor, and send to withdrawal straightening machine frequency converter, amplitude limit control is carried out to motor for withdrawal & straightening machine moment.

Motor for withdrawal & straightening machine negative moment amplitude limit value is:

Wherein, M is negative moment amplitude limit calculated value, and D is roller footpath, and Gr is gear-box gear ratio, T ₁for withdrawal straightening machine section strip steel tension force setting value

The given value of current value of withdrawal straightening machine frequency converter is:

I _{spc_min}＝-I _q

Wherein, I _{spc_min}the amplitude limit setting value of withdrawal straightening machine inverter current controller, I _qit is the torque current value of motor for withdrawal & straightening machine.I _{withdrawal straightening machine}for withdrawal straightening machine rated current, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, n is the actual speed of motor for withdrawal & straightening machine.

When carrying out amplitude limit to motor for withdrawal & straightening machine moment and controlling, motor for withdrawal & straightening machine speed ring is in saturation state, by additional for a motor for withdrawal & straightening machine speed preset a reference value stack velocity, and the motor for withdrawal & straightening machine speed preset value of additional stack velocity is sent to withdrawal straightening machine frequency converter, make to there is deviation all the time between withdrawal-straightener speed actual value and set-point, realizing withdrawal straightening machine frequency converter speed ring is saturation state, and output valve is 100%.For the motor for withdrawal & straightening machine speed preset value making motor for withdrawal & straightening machine speed ring be in saturation state is:

V _set＝V _line+V _overide

Wherein, V _setgiven for making motor for withdrawal & straightening machine speed ring be in the motor for withdrawal & straightening machine speed preset value of saturation state; V _linefor motor for withdrawal & straightening machine speed preset a reference value; V _overidefor stack velocity, span 10 ~ 50mpm.

2) indirect tension measuring appliance obtains the moment values of the withdrawal straightening machine frequency converter that withdrawal straightening machine frequency converter sends, and converts the negative tension force actual value of band steel to, that is:

I ₁＝I ₃-I ₂

$I_2=\frac{\mathrm{dn}}{\mathrm{dt}}\×C_1$

$T_{1\mathrm{act}}=-\frac{I_1}{D}$

Wherein: T _1actfor negative tension force actual value, I ₂for withdrawal straightening machine moment of accelerating electric current, C ₁for moment of accelerating conversion coefficient, J _{withdrawal straightening machine}for withdrawal straightening machine rotary inertia, D is roller footpath, and Gr is gear-box gear ratio, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, N _{withdrawal straightening machine}for the rated speed of motor for withdrawal & straightening machine, for withdrawal straightening machine accekeration, I ₁, I ₃be respectively withdrawal straightening machine section strip steel and set up torque current needed for tension force, motor for withdrawal & straightening machine actual measurement torque current.

3) the negative tension force actual value of band steel and tension force setting value are compared, if deviation is less than the tension force deviate of setting, then complete and the negative tension force of band steel is controlled, otherwise proceed step 1), until the band negative tension force actual value of steel and the deviation of setting value are less than the negative tension force deviate of setting.

$\mathrm{\Δ}{T}_1=\frac{|T_1-T_{1\mathrm{act}}|}{T_1}$

Wherein, Δ T ₁for withdrawal straightening machine section strip steel bears the deviation of tension force actual value and setting value; T ₁for the setting value of withdrawal straightening machine section strip steel tension force; T _1actfor withdrawal straightening machine section strip steel bears tension force actual value.

(5) if the withdrawal straightening machine section strip steel tension force setting value that given tension device exports is greater than 0, then selector selects positive tension controller to carry out positive tension force control to band steel, realizes strip tension in descaling bath and improves the function of less than 10%.Positive tension force control procedure is as follows:

1) direct tonometry device obtains the withdrawal straightening machine section strip steel tension force analog value that withdrawal straightening machine survey Zhang Yi records, and digitized of going forward side by side process obtains the positive tension force actual value T of band steel _2act, that is:

$T_{2\mathrm{act}}=\frac{F_R}{80}\×(\frac{F}{16}-200)$

Wherein, T _2actfor the positive tension force actual value of withdrawal straightening machine section, F _ruse by tensiometer the rated value of pressure head, the tension force analog value of F measured by tensiometer.

2) positive tension controller adoption rate integration control mode, the relatively positive tension force actual value of withdrawal straightening machine section strip steel and strip tension setting value, export motor for withdrawal & straightening motor speed adjustment amount to withdrawal straightening machine frequency converter, PLC sends motor for withdrawal & straightening machine Velocity Reference set-point to withdrawal straightening machine frequency converter simultaneously, motor for withdrawal & straightening motor speed adjustment amount and motor for withdrawal & straightening machine Velocity Reference set-point combine by withdrawal straightening machine frequency converter, total set-point as motor for withdrawal & straightening motor speed adjusts motor for withdrawal & straightening motor speed, thus realizes controlling the positive tension force of withdrawal straightening machine section strip steel.

ΔT ₁＝T ₁-T _2act

V _tech＝K _P×ΔT ₁+∑K _I×ΔT ₁×t ₂

V _set1＝V _line+V _tech

Wherein, V _linefor motor for withdrawal & straightening machine Velocity Reference set-point, set in PLC; V _techfor the speed adjustment amount that withdrawal straightening machine section tension controller exports; V _set1the total set-point of speed for motor for withdrawal & straightening machine; K _pfor proportional gain factor, K _ifor integration gain factor, t ₂for program scanning cycle time.

3) the positive tension force actual value of band steel and tension force setting value are compared, if deviation is less than the positive tension force deviate of setting, then complete and the positive tension force of band steel is controlled, otherwise proceed step 1), until the band positive tension force actual value of steel and the deviation of setting value are less than the tension force deviate of setting.

$\mathrm{\Δ}{T}_2=\frac{|T_1-T_{2\mathrm{act}}|}{T_1}$

Wherein, Δ T ₂for the deviation of the positive tension force actual value of withdrawal straightening machine section strip steel and setting value; T ₁for the setting value of withdrawal straightening machine section strip steel tension force; T _2actfor the positive tension force actual value of withdrawal straightening machine section strip steel.

Control method of the present invention is novel, can be widely used in the place needing to carry out negative tension force control, can not only improve pickling section strip steel surface quality, and can also reduce the consumption of holder stone, provides technological means for improving strip surface quality, meets and produces and technological requirement.

Claims (9)

1. the tension control method of cold-strip steel in a sour tandem rolling operation, described sour tandem rolling operation unit comprises withdrawal straightening machine, withdrawal straightening machine is surveyed Zhang Yi, descaling bath and descaling bath and surveyed Zhang Yi, described withdrawal straightening machine is arranged on the last procedure of descaling bath, it is characterized in that: this tension control method makes strip tension in descaling bath reach setting requirement by the strip tension of adjustment withdrawal straightening machine section, adopt withdrawal straightening machine frequency converter and the strip tension of PLC to withdrawal straightening machine section to control, described control method step is as follows:

(1) according to the band sectional area of steel and the relation of tension force, set up strip tension and withdrawal straightening machine section strip steel tension force static table in descaling bath, and described static table is stored in PLC internal memory, in the descaling bath stored in this static table, strip tension value is the setting value of strip tension in descaling bath;

(2) PLC is according to the specification treating pickled steel strip, obtain the sectional area being with steel, and by the static table described in search step (1), obtain strip tension value in withdrawal straightening machine section strip steel tension value and descaling bath, thus determine to make strip tension in descaling bath reach the withdrawal straightening machine section strip steel tension force setting value of its setting value;

(3) PLC judges the size of withdrawal straightening machine section strip steel tension force setting value, if withdrawal straightening machine section strip steel tension force setting value is less than 0, then enters step (4); If the setting value of withdrawal straightening machine section strip steel tension force is greater than 0, then PLC receives withdrawal straightening machine and surveys a tension force analog quantity for instrument measurement, digitized processing is the positive tension force actual value of band steel, and compare with withdrawal straightening machine section strip steel tension force setting value, export motor for withdrawal & straightening motor speed adjustment amount in withdrawal straightening machine frequency converter, the speed of withdrawal straightening machine frequency converter to motor for withdrawal & straightening machine adjusts, and realizes controlling the positive tension force of withdrawal straightening machine section strip steel, and enters step (6);

(4) PLC receives the motor for withdrawal & straightening machine actual speed that withdrawal straightening machine frequency converter sends, and withdrawal straightening machine section strip steel tension force setting value is converted to the motor negative moment amplitude limit value of withdrawal straightening machine, the given value of current value of withdrawal straightening machine frequency converter is obtained according to the rotating speed of described motor negative moment amplitude limit value and motor, and send to withdrawal straightening machine frequency converter, amplitude limit control is carried out to motor for withdrawal & straightening machine moment, realizes controlling the negative tension force of withdrawal straightening machine section strip steel;

(5) PLC receives the motor for withdrawal & straightening machine moment values that withdrawal straightening machine frequency converter sends, and obtains the negative tension force actual value of withdrawal straightening machine section strip steel according to described motor for withdrawal & straightening machine moment values;

(6) compare the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value, if described deviation is less than the tension force deviate of setting, then complete the control of strip tension in a descaling bath; Otherwise, continue to adjust the tension force of withdrawal straightening machine section strip steel, until the positive tension force actual value of withdrawal straightening machine section strip steel and setting value deviation are less than the tension force deviate of setting, realize the control to the strip tension in descaling bath.

2. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (1), and in described descaling bath, strip tension and withdrawal straightening machine section strip steel tension force static table are:

。

3. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (2), describedly determines that the method for withdrawal straightening machine section strip steel tension force setting value is:

T ₄＝Bg(2)

T ₁＝Bg(1)-Bg(2)-(T ₂+T ₃)×0.95

Wherein, Bg (1) is the withdrawal straightening machine section strip steel tension value that search static table obtains, strip tension value in the descaling bath that Bg (2) search static table obtains, T ₁for withdrawal straightening machine section strip steel tension force setting value, T ₂be the strip tension setting value between the 3rd jockey pulley and the 4th jockey pulley, T ₃be the tension force setting value between the 4th jockey pulley and the 5th jockey pulley, T ₄for strip tension setting value in acid tank.

4. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (4), by the method that withdrawal straightening machine section strip steel tension force setting value converts motor for withdrawal & straightening machine negative moment amplitude limit calculated value to is:

Wherein, M is negative moment amplitude limit calculated value, and D is roller footpath, and Gr is gear-box gear ratio, T ₁for withdrawal straightening machine section strip steel tension force setting value.

5. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 4, is characterized in that in described step (4), the given value of current value of withdrawal straightening machine frequency converter is:

I _{spc_min}＝-I _q

Wherein, I _{spc_min}the amplitude limit setting value of withdrawal straightening machine inverter current controller, I _qthe torque current value of motor for withdrawal & straightening machine, I _{withdrawal straightening machine}for withdrawal straightening machine rated current, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, n is the actual speed of motor for withdrawal & straightening machine.

6. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (5), the method obtaining negative tension force actual value is:

I ₁＝I ₃-I ₂

Wherein: T _1actfor negative tension force actual value, C ₁for moment of accelerating conversion coefficient, J _{withdrawal straightening machine}for withdrawal straightening machine rotary inertia, D is roller footpath, and Gr is gear-box gear ratio, P _{withdrawal straightening machine}for withdrawal straightening machine rated power, N _{withdrawal straightening machine}for the rated speed of motor for withdrawal & straightening machine, for withdrawal straightening machine accekeration, I ₁for withdrawal straightening machine section strip steel sets up torque current needed for tension force, I ₂for withdrawal straightening machine moment of accelerating electric current, I ₃for motor for withdrawal & straightening machine actual measurement torque current.

7. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (6), the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value is:

Wherein, Δ T is the deviation of withdrawal straightening machine section strip steel tension force actual value and setting value; T ₁for the setting value of withdrawal straightening machine section strip steel tension force; T _actfor withdrawal straightening machine section strip steel tension force actual value; When negative tension force controls, T _actequal negative tension force actual value; When positive tension force controls, T _actequal positive tension force actual value.

8. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (3), withdrawal straightening machine is surveyed the method that tension force analog value that Zhang Yi obtains is converted to positive tension force actual value to be:

Wherein, T _2actfor positive tension force actual value, F _ruse by tensiometer the rated value of pressure head, the tension force analog value of F measured by tensiometer.

9. the tension control method of cold-strip steel in the sour tandem rolling operation according to claims 1, is characterized in that in described step (3), to the control adoption rate integration control mode of the positive tension force of band steel.