JP2011088173A - Device and method for controlling tension of cold rolling mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in sheet thickness and also to prevent troubles such as breakage of a rolled stock by controlling tension so that rolling load is constant when accelerating and decelerating rolling speed in a continuous cold rolling. <P>SOLUTION: A device 30 for controlling the tension of a cold rolling mill is the one for controlling the tension of the rolled stock W which is rolled with the cold rolling mill provided with one or a plurality of rolling stands 1. The rolling controller has a tension curve calculating part 31 where the relationship between the rolling speed and a tension between stands is calculated by assuming that the coefficient of friction between the rolling rolls 3 of the rolling stands 1 and the rolled stock W and the deformation resistance of the rolled stock W are depended on the rolling speed and a tension control part 32 where the speed of the rolling rolls 3 of the rolling stand 1 during acceleration and deceleration is controlled on the basis of the relationship between the rolling speed and the tension between stands, which is calculated by the tension curve calculating part 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tension control device and a tension control method for a cold rolling mill that can appropriately control the tension of a rolled material during acceleration / deceleration of the rolled material that is cold-rolled continuously.

Conventionally, as a tension control method used when continuously rolling a rolled material in a cold state, a table value is previously obtained using a relationship between a rolling speed and a tension between stands, and the tension between stands is determined based on the table value. The technique of controlling is used.
By the way, as shown in FIG. 2, during the cold continuous rolling, the rolling speed may be decreased or conversely increased. For example, in a kind of cold rolling mill, an operation called “coil rewinding” is performed. The rewinding of the coil refers to an operation of separating the coiled preceding rolled material from a series of rolled materials that are continuously rolled. At the time of such coil rewinding, after the rolling speed is reduced, rolling may be temporarily interrupted and the rolling speed may become zero. In continuous rolling, in order to continuously roll the preceding rolled material and the subsequent rolled material, an operation of butt welding the rear end portion of the preceding rolled material and the front end portion of the subsequent rolled material is performed. During the abutting operation or when the abutting portion passes through the rolling stand, the rolling speed may be low or zero.

That is, at the time of coil rewinding or continuous rolling, the rolling speed is reduced from the steady speed (V2 in FIG. 2) during the rolling, or then accelerated to the steady speed (V5 in FIG. 2). There is an acceleration / deceleration state where the speed is 10% or less of the steady state.
However, in the above-described method of “table value relation between rolling speed and tension between stands in advance”, since the thickness, material (strength), width, etc. are different for each rolled material, all rolling states, especially There is a problem that it is difficult to convert the relationship between the rolling speed and the tension between the stands into a table value with respect to the acceleration / deceleration state. In addition, when the relationship between the rolling speed and the tension between the stands is deviated from the table value during acceleration / deceleration, manual intervention by the operator is performed. Troubles such as excessively raising the rolled material may occur.

Patent Documents 1 and 2 disclose a technique that can avoid such inconveniences, that is, a plate thickness tension control method that can cope with acceleration / deceleration.
Japanese Patent Laid-Open No. 2004-260688 discloses a method for controlling the rolling speed in a plate thickness correction control method for plate thickness fluctuations for an acceleration / deceleration unit for producing a plate having a uniform thickness in the longitudinal direction when rolling the plate with a continuous tandem rolling mill. During deceleration, the correction amount is calculated according to the steel type, plate thickness, acceleration / deceleration amount, acceleration / deceleration rate, and the calculated correction amount is added to the speed command value or tension command value. A control technique is disclosed.

  In Patent Document 2, when rolling a rolled material using a rolling apparatus provided with a plurality of rolling stands and a plate thickness tension control unit that controls the rolling stand, the rolling material is accelerated or decelerated. Are the input parameters that are the parameters on the input side of the plate thickness tension control unit and the parameters on the output side of the plate thickness tension control unit itself or the plate thickness tension control unit so that the finished plate thickness is within the target range. A technique for optimizing control parameters using a rolling dynamic model capable of expressing rolling transient characteristics, and controlling each rolling stand using optimized input parameters and control parameters is disclosed.

JP 2003-181511 A JP 2007-289990 A

However, in the control method described in Patent Document 1, although the steel type, the plate thickness, and the amount of acceleration / deceleration correction at the time of acceleration / deceleration are presented in the form of a table or curve, the specifics of the table or curve are specific. No such determination method is disclosed. Therefore, it seems difficult to apply the correction amount at the time of acceleration / deceleration to an actual rolling apparatus having various forms.
In addition, the control method described in Patent Document 2 optimizes the input parameter (for example, tension correction amount) of the plate thickness tension control unit and the control parameter (for example, roll speed and / or roll gap) as output parameters at the same time. And optimized input parameters and control parameters are output. However, since this simultaneous optimization process requires calculation time and is complicated, it is difficult to say that this method is suitable for on-line control of plate thickness and tension.

In other words, the techniques of Patent Document 1 and Patent Document 2 cannot reliably perform tension control during acceleration / deceleration in cold continuous rolling.
The present invention has been made in view of the above situation, and suppresses variation in sheet thickness by controlling the tension so that the rolling load is constant during acceleration and deceleration of the rolling speed in cold continuous rolling. It is another object of the present invention to provide a tension control device and a tension control method for a cold rolling mill that can prevent troubles such as breakage of a rolled material.

In order to achieve the above-described object, the present invention takes the following technical means.
A tension control device for a cold rolling mill according to the present invention is a tension control device for controlling the tension of a rolled material rolled by a cold rolling mill provided with one or a plurality of rolling stands, and the rolling control device includes: The friction coefficient between the rolling roll of the rolling stand and the rolled material and the deformation resistance of the rolled material depend on the rolling speed, and a tension curve calculating unit for calculating the relationship between the rolling speed and the tension between the stands, And a tension control unit that controls the peripheral speed of the rolling roll during acceleration / deceleration based on the relationship between the rolling speed calculated by the tension curve calculating unit and the tension between stands.

  Preferably, the tension curve calculation unit determines that the friction coefficient and deformation resistance depend on the rolling speed as in the formulas (1) and (2), and the rolling load at the time of acceleration / deceleration is constant. It may be configured to calculate the relationship between the speed and the tension between the stands.

Where μ: friction coefficient, μ ₀ : asymptotic value of the friction coefficient asymptotically increasing with increasing rolling speed,
μ ₁ : Difference in friction coefficient between when the rolling speed is sufficiently high and zero,
k: deformation resistance, k ₀ : asymptotic value of deformation resistance asymptotically increasing with increasing rolling speed,
k ₁ : difference in deformation resistance when the rolling speed is sufficiently high and zero,
V: rolling speed, a, b: speed dependent coefficient Further, the tension control method of the cold rolling mill according to the present invention is the tension of the rolling material rolled by the cold rolling mill provided with one or a plurality of rolling stands. The method of controlling, the friction coefficient between the rolling roll of the rolling stand and the rolling material and the deformation resistance of the rolling material is dependent on the rolling speed, calculating the relationship between the rolling speed and the tension between the stands, The peripheral speed of the rolling roll is controlled based on the calculated relationship between the rolling speed and the tension between the stands.

  Preferably, the friction coefficient and the deformation resistance of the rolled material depend on the rolling speed as shown in equations (1) and (2), and the rolling load at the time of acceleration / deceleration is constant. It is good to calculate the relationship between the tensions.

Where μ: friction coefficient, μ ₀ : asymptotic value of the friction coefficient asymptotically increasing with increasing rolling speed,
μ ₁ : Difference in friction coefficient between when the rolling speed is sufficiently high and zero,
k: deformation resistance, k ₀ : asymptotic value of deformation resistance asymptotically increasing with increasing rolling speed,
k ₁ : difference in deformation resistance when the rolling speed is sufficiently high and zero,
V: rolling speed, a, b: speed dependence coefficient

  According to the tension control device and the tension control method of the cold rolling mill of the present invention, by controlling the tension so that the rolling load is constant at the time of acceleration / deceleration of the rolling speed in the cold continuous rolling of the rolled material, Thickness variation can be suppressed and troubles such as breakage of the rolled material can be prevented.

It is a figure which shows the principal part of the cold tandem rolling mill to which the plate | board thickness control apparatus which concerns on this invention was applied. It is the figure which showed the rolling condition in the connection part vicinity of a preceding rolling material and a succeeding rolling material. (A) is a figure which shows the relationship between the rolling speed at the time of deceleration, and a friction coefficient, (b) is a figure which shows the relationship between the rolling speed at the time of deceleration, and deformation resistance. It is a figure which shows an example of the tension control curve of this invention. It is a flowchart of the process performed with the plate | board thickness control apparatus which concerns on this invention (at the time of deceleration). It is the figure which showed the fluctuation | variation of the rolling load at the time of controlling using the tension control curve of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings while illustrating a cold tandem rolling mill 2 including a plurality of rolling stands 1.
In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
The cold tandem rolling mill 2 includes a plurality of rolling stands 1 and a coil winder that winds the rolled material W after rolling. In FIG. A plurality of rolling stands 1 existing in FIG.

The rolling stand 1 includes upper and lower rolling rolls 3 (work rolls) and backup rolls 4 that back up the respective rolling rolls 3. The roll amount of the rolling roll 3 of the rolling stand 1 can be changed by the reduction mechanism 5. Each rolling stand 1 is provided with a load meter 6 for measuring a rolling load.
On the exit side of the rolling stand 1, a plate thickness meter 7 for detecting the plate thickness of the rolled material W and a plate speed meter 8 for measuring the speed of the rolled material W are provided. Between the rolling stand 1 and the rolling stand 1, a tension meter 9 capable of detecting the tension between the rolling stands 1 is also provided.

In this cold tandem rolling mill 2, the rolled material W is cold-rolled by passing through a plurality of rolling stands 1 to obtain a product plate having a desired plate thickness, plate width, and plate crown, and coil winding. It is wound up by a machine and conveyed to the next process.
The cold tandem rolling mill 2 is provided with a plate thickness control device (not shown) that controls a gap amount between the rolling rolls 3 by moving a reduction mechanism 5 provided in the rolling stand 1. The plate thickness control device controls at least one or all or all of the rolling stands 1 of the cold tandem rolling mill 2.

  The plate thickness control device is configured by a process control, a PLC, or the like, and includes an AGC control unit that performs AGC control. The AGC control unit controls the roll gap of each rolling stand 1 with a predetermined proportional gain so as to compensate for the amount of change in the roll gap accompanying the deviation of the rolling load in each rolling stand 1. Specifically, control called BISRA-AGC or variable mill stiffness control is performed, and the plate thickness variation is represented by a component accompanying the load variation and a component due to the operation amount of the roll gap, and control is performed to bring the plate thickness variation close to zero. Further, the plate thickness control device includes a gain determining means for determining a proportional gain used in the AGC control unit according to the rolling speed of the rolling stand 1. A value of 1.0 or less is used as the tuning rate α in order to prevent over-response due to interference with the identification error of the mill rigidity M and the AGC control in the steady state.

Furthermore, the cold tandem rolling mill 2 is provided with a tension control device 30 that controls the tension between the stands of the rolled material W by making the rotation speed (roll peripheral speed) of the rolling roll 3 provided in the rolling stand 1 variable. Yes. The tension control device 30 controls the speed of the rolling rolls 3 of at least one or all of the cold tandem rolling mills 2 or all of the rolling stands 1.
The tension control device 30 is composed of a process controller, a PLC, or the like, and includes a tension curve calculation unit 31 that graphs the relationship between the rolling speed and the tension between stands or graphs the table. The tension curve calculation unit 31 has a condition that the rolling load is constant in deriving the relationship between the rolling speed and the tension between the stands. By controlling the tension under these conditions, fluctuations in the plate thickness can be suppressed as much as possible. The tension control device 30 includes a tension control unit 32 that controls the speed of the rolling roll 3 of the rolling stand 1 based on the relationship between the rolling speed calculated by the tension curve calculating unit 31 and the tension between the stands.

Details of the tension curve calculation unit 31 and the tension control unit 32 are as follows.
In the tension curve calculation unit 31, the friction coefficient and the deformation resistance are expressed with respect to an existing rolling load model (for example, Hill's approximate solution) based on actual operation data as shown in FIG. As shown in equation (2), modeling is performed so as to have speed dependency. Then, using Expressions (1) and (2), a relational expression between the rolling speed and the tension between the stands as in Expression (3) is constructed. to create a tension curve to calculate the _in.

Where μ: friction coefficient, μ ₀ : asymptotic value of the friction coefficient asymptotically increasing with increasing rolling speed,
μ ₁ : Difference in friction coefficient between when the rolling speed is sufficiently high and zero,
k: deformation resistance, k ₀ : asymptotic value of deformation resistance asymptotically increasing with increasing rolling speed,
k ₁ : difference in deformation resistance when the rolling speed is sufficiently high and zero,
V: rolling speed, a, b: speed dependence coefficient

Where σ _in : tension between stands on the entry side of the rolling stand 1, σ _out : tension between stands on the exit side of the rolling stand 1, P: rolling load, W: plate width, L: contact length with the rolling roll , R ′: flat roll radius, Δh: reduction amount, r: reduction ratio, V: rolling speed, k: deformation resistance.
In formula (3), subscripts i = 2 to n (n is the number of the final rolling stand), and n corresponds to the total number of stands. As will be described later, these equations are derived by making the rolling load of the rolling stand 1 constant.

  As described above, if the tension between the stands during acceleration / deceleration is controlled based on the tension curve obtained from Equation (3), even if the operator manually intervenes during rolling, the rolling situation of deceleration or acceleration The balance of speed and tension according to the actual condition can be always satisfied, and appropriate tension control is possible. Further, in each rolling stand 1, the rolling load is controlled to be constant (derivation of formula (4) → formula (5) described later), so that fluctuations in sheet thickness can be reliably suppressed.

On the other hand, the tension control unit 32 reads the rolling speed at the time of deceleration / acceleration described above from the tension curve calculated by the tension curve calculation unit 31, calculates the tension between the stands, and calculates the measured inter-stand tension. Find the deviation Δσ _in . In accordance with the tension deviation Δσ _in , a correction amount ΔV of the rolling speed is obtained (the relation between Δσ _in and ΔV is obtained through the advanced rate), and the roll circumference of each rolling stand 1 is considered in consideration of the constraint condition of constant mass flow. Adjust the speed.

In the tension control unit 32, the values of the stand entry side tensions σ _in ^(i-1) to ⁱ obtained by the equations (2) and (3) are allowable values, that is, the breaking stress σ _{B of the} rolled material W. When exceeding × C (C: safety factor <1), each stand entry side tension σ _in ⁽ⁱ⁻¹⁾ to ⁱ = breaking stress σ _B × C. By carrying out like this, troubles, such as a fracture of rolling material W, can be prevented.
Next, the derivation of Equation (3) used in the tension curve calculation unit 31 will be described in detail.

First, as factors affecting the rolling load P in the rolling stand 1, the friction coefficient mu, mention may be made of deformation resistance k _m, the entry side tension of the rolling stand 1 sigma _in and outgoing side tension sigma _out. Considering these factors, the rolling load variation ΔP can be expressed as shown in Equation (4).

  In the present invention, the expression (5) is derived by setting ΔP = 0 in the expression (4) with the intention of eliminating the fluctuation of the rolling load ΔP during tension control.

From equation (5), the tension change Δσ _{in on the} rolling mill entry side is

From equation (6), the advance understand the dependence on the rolling speed of the friction coefficient μ and deformation resistance k _m, by giving tension change .DELTA..sigma _out of the rolling stand 1 the delivery side, in association with the rolling speed The change _in tension Δσ _in on the entrance side of the rolling mill can be obtained.
In equation (6), for the rolling load P, the friction coefficient mu, the tension sigma _in the rolling mill inlet side and outlet side, sigma _out, it is necessary to calculate the influence coefficient of the deformation resistance k _m, existing for rolling theoretical formula It is more practical to obtain the tension change σ _in on the rolling mill entry side in correspondence with the rolling speed as follows using

  The rolling load P can be expressed as the rolling force function Q by, for example, the following expression (7) using Hill's approximate expression.

Here, W: plate width, L: contact length of rolling roll, R ′: flat roll radius, Δh: rolling amount, r: rolling ratio, α, β: coefficient.
(K _m −α × σ _in −β × σ _out ) _in the second term on the right side of the equation (7) is an influence term of the entry side tension σ _in and the exit side tension σ _out of the rolling stand 1. = 0.7 and β = 0.3 are used.
As the flat roll radius R ′, the following Hitchcock roll flat type can be used.

In the formulas (8) and (9), R: roll radius, ν ₀ : Poisson's ratio, E ₀ : Young's modulus.
Regarding the reduction amount Δh, the reduction rate r, and the rolling load P in the equations (7) to (9), measured data in the steady state before entering the deceleration state can be used in the deceleration process. Moreover, in the acceleration process, the setting value of the draft schedule of the next coil (following rolling material) at the time of setup can be used.

  On the other hand, the friction coefficient μ and the deformation resistance k in consideration of the influence of the rolling speed V are the actual coefficient data of the friction coefficient between the roll and the rolled material W and the deformation resistance of the rolled material W as shown in FIG. Considering the above, it is expressed as Expression (1) and Expression (2).

Here, μ: friction coefficient, V: rolling speed, a: speed dependence coefficient, k: deformation resistance V: rolling speed, b: speed dependence coefficient.
In Equation (1), μ ₀ is the friction coefficient μ when the rolling speed is assumed to be infinitely large (V = V∞), and μ ₁ is the case where the rolling speed is infinitely large (V = V∞). It means the difference in friction coefficient between zero (V = 0) and hypothesis, and the speed dependence coefficient a is a correction coefficient when the relationship between the rolling speed V and the friction coefficient μ is approximated by an exponential function.

These μ ₀ , μ ₁ , and a can be determined from the operation performance data shown in FIG. 2A by, for example, regression analysis such as a least square method.
In equation (2), k ₀ is the deformation resistance when the rolling speed approaches infinitely zero, and k ₁ is the deformation when the rolling speed is infinitely large (V = V∞) and zero. The difference in resistance is shown respectively, and the speed dependence coefficient b is a correction coefficient when the relationship between the rolling speed V and the deformation resistance k is approximated by an exponential function. These k ₀ , k ₁ , and b can be determined from the regression analysis of the operation result data shown in FIG. 2B, as in the case of the friction coefficient.

By substituting Equation (1) and Equation (2) into Equation (7), the entry side tension σ _in of the rolling stand 1 is related to the rolling speed V and becomes as in Equation (10).

When Expression (10) is expressed as a general expression as the entry side tension σ _in between each rolling stand in the cold tandem rolling mill 2 shown in FIG. 1, Expression (3) is obtained.

Where σ _in : tension between stands on the entry side of the rolling stand 1, σ _out : tension between stands on the exit side of the rolling stand 1, P: rolling load, W: sheet width, L: contact length of the rolling roll, R ′: flat roll radius, Δh: reduction amount, r: reduction ratio, V: rolling speed.
In formula (3), subscripts i = 2 to n (n: final rolling stand 1 number).
As an example, when the cold tandem rolling mill 2 is composed of five rolling stands 1, the entry side tension σ _in ⁽⁴ to ⁵⁾ of the # 5 rolling stand 1 is as follows.

The entrance-side tensions σ _in ⁽³ to ⁴⁾ , σ _in ⁽² to ³⁾ , and σ _in ⁽¹ to ²⁾ of the rolling stands 1 of # 2 to # 4 can be similarly determined.
In Expression (11), the exit side tension σ _out ⁽⁵ ) of the # 5 rolling stand 1 is a winding tension, and is therefore a constant value (known). Further, the entry side tension σ _in ⁽⁴ to ⁵⁾ of the # 5 rolling stand 115 is equal to the exit side tension σ _out ⁽⁴⁾ of the # 4 rolling stand 1. The entry side tensions σ _in ⁽³ to ⁴⁾ , σ _in ⁽² to ³⁾ , and σ _in ⁽¹ to ^{2) of the} rolling stands 1 of # 2 to # 4 are also rolled in # 1 rolling stands 1 to # 3, respectively. It is equal to the exit side tensions σ _out ⁽¹ to ²⁾ , σ _out ⁽² to ³⁾ , and σ _out ⁽³ to ⁴⁾ of the stand 1.

In this way, as shown by the equation (3), the entry side tension σ _in of each rolling stand 1 corresponding to the change in rolling speed, that is, the tension between the stands can be obtained, and a tension curve can be created. .
Incidentally, the deformation resistance k corresponding to the rolling speed (strain rate) is the deformation resistance ^{_{data, k = c × ε s n}} × ε r m the form (material processing Computational Mechanics, Japan plastic working Gakkai, Corona Publishing Co., 1992, see page 5) and can be calculated by obtaining the strain rate ε _r from the rolling speed and strain ε _s .

FIG. 4 shows, as an example, the relationship between the rolling speed V calculated by the expression (3) and the entry side tension σ _in of the # 5 rolling stand 1, that is, the tension curve of the tension between # 4 to # 5 rolling stands 1. Is.
In FIG. 4, as the rolling speed V decreases, the entry side tension σ _in (inter-stand tension) necessary to keep the rolling load P constant increases. Since the entry side tension σ _in needs to be smaller than the breaking stress σ _B of the rolled material W, on the low rolling speed side, the maximum value of σ _in is the breaking stress σ _B , and practically σ _B × C (C: safety factor). That is, σ _in has a constant value _in the low speed state. Moreover, it turns out that the entrance side tension | tensile_strength of # 4 rolling stand 1 is increasing under the influence of this (sigma) _in .

Similarly, the entry side tension σ _in ⁽³ ~ ⁴⁾ of each rolling stand 114-12 of ^{_{# 4~ # 2, σ in (}} 2 ~ 3), for even σ _in ⁽¹ ~ ^2), downstream of the rolling direction A tension curve can be created in order from the side stand to the upstream side stand.
FIG. 5 is a flowchart showing an outline of “tension control when the rolled material W is decelerated” executed in the tension control device 30. This flowchart shows a process in the case where the cold tandem rolling mill 2 is composed of five rolling stands 1.

First, in S10, it is confirmed that the rolling state has entered the deceleration state from the steady state.
After that, in S20, the tension σ _m (the tension between the rolling stands of # 1 to # 5, which is the entry side tension, at a predetermined sampling period with the exit side rolling speed V ⁽²⁾ of the # 1 rolling stand 1 as a reference. i) (i = 2 to 5), inlet side thickness h _in ^(i), outgoing side thickness h _out ⁽ⁱ⁾ and outgoing side rolling speed V ⁽ⁱ⁾ are tensiometer 9, thickness gauge 7 and plate speed meter 8 is measured respectively.

Next, the entry side tension σ _in ⁽ⁱ⁾ (i = 2 to 5) necessary for keeping the rolling load P constant is obtained from the tension curve illustrated in FIG. Then, the entry side tension deviation Δσ _in ⁽ⁱ⁾ (= σ _in ⁽ⁱ⁾ −σ _in (ob) ⁽ⁱ⁾ (i = 2 to 5) of each rolling stand 1 is calculated.
Further, a correction amount ΔV ⁽ⁱ⁾ of the rolling speed V ⁽ⁱ⁾ with respect to the entry-side tension deviation Δσ _in ^{(i )} , that is, a correction amount ΔV _R ⁽ⁱ⁾ of the roll peripheral speed V _R is calculated. For example, it can be calculated by obtaining _in advance the influence coefficient ∂fs / ∂σ _in ⁽ⁱ⁾ of the entry side tension σ _in ⁽ⁱ⁾ with respect to the advance rate fs based on the equation (12).

Where V _in ⁽ⁱ⁾ : #i rolling speed at the entry side of the rolling stand, h _in ⁽ⁱ⁾ : #i entrance thickness of the rolling stand, h _out ⁽ⁱ⁾ : #i exit thickness of the rolling stand is there.
The correction amount of the correction amount [Delta] V ⁽ⁱ⁾ i.e. a roll circumferential speed V _R of the rolling speed V ⁽ⁱ⁾ for the entrance side tension deviation ^{_{Δσ in (i) ΔV R (}} i) is calculated in advance using the formula (12) For example, it can be stored in the tension control device 30 in a table value format.

By the way, in the rolling process, it is necessary to always keep the mass flow constant. In practice, the rolling speed is corrected (adjusted) to the downstream side based on the rolling speed of the # 1 rolling stand 1 of the cold tandem rolling mill 2. when the in the following flow (order) to adjust the roll peripheral speed V _R of the rolling stand 1.
First, at S30, for the # 2 rolling stand 1, the entry side tension σ _in ⁽ necessary for keeping the rolling load P constant from the tension curve as shown in FIG. ²⁾ is obtained, and a deviation Δσ _in ⁽²⁾ from the actually measured tension σ _in (ob) ⁽²⁾ between the rolling stands 1 is calculated.

In S40, the tension deviation Δσ _in ⁽²⁾ is substituted into Δσ _in ⁽ⁱ⁾ _in the equation (12 ⁾ to calculate the correction amount ΔV _R ⁽²⁾ of the roll peripheral speed V _R ^(2). from the correction amount [Delta] V _R of the circumferential speed V _R ^{(2) (2),} via a forward slip fs ^(2), it is possible to calculate the correction amount of rolling speed V ⁽²⁾ [Delta] V ^(2).
In S50, by adjusting (correcting) the roll peripheral speed V _R ⁽²⁾ of the # 2 rolling stand 1 by ΔV _R ⁽²⁾ , at the same time as this adjustment, the constant mass flow is satisfied. The correction rate ΔV ^{(3) to} ΔV ⁽⁵⁾ of the rolling speed of the three rolling stands 1 to # 5 rolling stand 1 is calculated by the equations (13) to (15), and the advanced rate fs ^{(3) to} fs ⁽⁵⁾ through, it calculates the correction amount ΔV ⁽³⁾ ~ΔV roll peripheral speed corresponding to ⁽⁵⁾ correction amount ^{_{ΔV R (3) ~ΔV R (}} 5).

At S60, # 2 roll peripheral speed of the rolling stand 1 at the same time is corrected by ΔV _R ^(2), # 3 rolling stand 1~ # ΔV _R ⁽³⁾ roll peripheral speed V _R of the rolling stand 1 of 5 ～DerutaV Adjust _R ⁽⁵⁾ all at once.
In S70, for the rolling stands 1 of # 3 to # 5, as shown below, the same steps as steps S30 to S60 for the # 2 rolling stand 1 are executed to correct the rolling speed (roll peripheral speed). To do.

For the # 3 rolling stand 1, the entry side tension σ _in ⁽³⁾ required to keep the rolling load P constant is obtained from the tension curve as shown in FIG. A deviation Δσ _in ⁽³⁾ from the actually measured tension σ _in (ob) ⁽³⁾ between the stands 1 is calculated. Then, .DELTA..sigma _in ⁽ⁱ⁾ of formula (12), calculates the correction amount [Delta] V _R of the tension deviation .DELTA..sigma _in ⁽³⁾ roll peripheral speed V _R ⁽³⁾ by substituting ^(3). From the correction amount [Delta] V _R of the roll peripheral speed V _R ^{(3) (3),} via a forward slip fs ^(3), can be calculated correction amount of the rolling speed V ⁽³⁾ [Delta] V ^(3).

By adjusting the roll peripheral speed V _R ⁽³⁾ of the # 3 rolling stand 1 by ΔV _R ⁽³⁾ and simultaneously satisfying the constant mass flow, the rolling speed ΔV of the # 4 rolling stand 1 to the # 5 rolling stand 1 is satisfied. ^{(4) to} ΔV ⁽⁵⁾ are adjusted all at once as shown in the formulas (14a) to (15a).

Actually, the rolling speeds ΔV ^{(4) to} ΔV ^{( 5)} are adjusted by changing the roll peripheral speed V _R obtained through the advance rates fs ^{(3) to} fs ⁽⁵⁾ to ΔV _R ⁽⁴⁾ and ΔV _R. ⁽⁵⁾ is applied to the rolling stand 1.
Next, for the # 4 rolling stand 1, the entry side tension σ _in ⁽ necessary for keeping the rolling load P constant from the tension curve as shown in FIG. 4 corresponding to the exit side rolling speed V ⁽⁴⁾ . ⁴⁾ is obtained, and the deviation Δσ _in ⁽⁴⁾ from the actually measured tension σ _in (ob) ⁽⁴⁾ between the rolling stands 113-14 is calculated. Then, .DELTA..sigma _in ⁽ⁱ⁾ of formula (12), calculates the correction amount [Delta] V _R of the tension deviation .DELTA..sigma _in ⁽⁴⁾ roll peripheral speed V _R ⁽⁴⁾ by substituting ^(4). From the correction amount [Delta] V _R of the roll peripheral speed V _R ^{(4) (4),} via a forward slip fs ^(4), it is possible to calculate the correction amount of the rolling speed V ⁽⁴⁾ [Delta] V ^(4).

By adjusting the roll peripheral speed V _R ⁽⁴⁾ of the # 4 rolling stand 1 by ΔV _R ⁽⁴⁾ and simultaneously satisfying the constant mass flow, the rolling speed V ⁽⁵⁾ of the # 5 rolling stand 1 is expressed by the formula ( Adjust by ΔV ⁽⁵⁾ as shown in 15b).

Actually, the adjustment of the rolling speed ΔV ⁽⁵⁾ adjusts the roll peripheral speed V _R obtained through the advance rate fs ⁽⁵⁾ by ΔV _R ⁽⁵⁾ .
Finally, for the # 5 rolling stand 1, the entry side tension σ _in ⁽⁵⁾ required to keep the rolling load P constant from the tension curve of FIG. 4 corresponding to the exit side rolling speed V ⁽⁵⁾ . And the deviation Δσ _in ⁽⁵⁾ from the actually measured tension σ _in (ob) ⁽⁵⁾ between the rolling stands 1 is calculated. The correction amount ΔV _R ⁽⁵⁾ of the roll peripheral speed V _R ⁽⁵⁾ can be calculated and adjusted by substituting the tension deviation Δσ _in ⁽⁵⁾ for Δσ _in ⁽ⁱ⁾ _in the equation (12). . From the correction amount [Delta] V _R of the roll peripheral speed _{^{V R (5) (5)}} , can be via a forward slip fs ^(4), calculates the correction amount of rolling speed ^{V (5) ΔV (5)} .

The above-described adjustment of the rolling speed to the downstream side in each rolling stand 1 is executed instantaneously for each predetermined sampling period of the tension control device 30.
In this way, it is possible to perform tension control for keeping the rolling load of each rolling stand 1 constant while satisfying the constant mass flow condition in the deceleration process.
FIG. 5 shows a cold tandem rolling mill 2 composed of a plurality of (5) rolling stands 1 and a steel sheet (soft steel, tensile strength: 20 kg / mm ² ) with an inlet side thickness of 3 mm and a finished thickness of 0. The simulation result (rolling load change) at the time of cold rolling to 8 mm is shown.

As is apparent from this figure, in the uncontrolled state, a decrease in the rolling speed is observed with a constant tension condition, but an increase in the rolling load is recognized, but it can be seen that the rolling load is controlled to be constant by applying this control.
The tension control described above is based on the entry rolling speed of the # 1 rolling stand 1, but the rolling speed is corrected upstream on the basis of the rolling speed of the # 5 rolling stand 1 (final rolling stand). You can also go. However, in the layout of the normal cold tandem rolling mill 2, the distance between the coil supply reel (payoff reel) and the # 1 rolling stand 1 is larger than the distance between the # 5 rolling stand 1 and the take-up reel. Therefore, it is more reasonable to use the rolling speed of the # 1 rolling stand 1 positioned on the upstream side as a reference.

In the acceleration process, tension control for keeping the rolling load of each rolling stand 1 constant can be performed using the tension curve shown in FIG. 4 as in the case of the deceleration process.
As mentioned above, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the embodiment for carrying out the invention, a cold tandem rolling mill provided with a plurality of rolling stands has been exemplified, but the present invention can be applied to a cold rolling mill composed of a single rolling stand.

DESCRIPTION OF SYMBOLS 1 Rolling stand 2 Cold tandem rolling mill 3 Roll roll 4 Backup roll 5 Reduction mechanism 6 Load meter 7 Plate thickness meter 8 Plate speed meter 9 Tensile meter 30 Tension control device 31 Tension curve calculation part 32 Tension control part W Rolling material

Claims (4)

A tension control device for controlling the tension of a rolled material rolled by a cold rolling mill equipped with one or a plurality of rolling stands,
The rolling control device is a tension curve for calculating the relationship between the rolling speed and the tension between the stands, assuming that the friction coefficient between the rolling roll of the rolling stand and the rolling material depends on the rolling speed. A calculation unit;
Based on the relationship between the rolling speed calculated by the tension curve calculation unit and the tension between stands, a tension control unit that controls the peripheral speed of the rolling roll during acceleration and deceleration,
There is provided a tension control device for a cold rolling mill. The tension curve calculation unit assumes that the friction coefficient and deformation resistance depend on the rolling speed as in the formulas (1) and (2), and that the rolling load at the time of acceleration / deceleration is constant. The tension control device for a cold rolling mill according to claim 1, wherein the tension control device is configured to calculate a relationship between the intermediate tensions.

Where μ: friction coefficient, μ ₀ : asymptotic value of the friction coefficient asymptotically increasing with increasing rolling speed,
μ ₁ : Difference in friction coefficient between when the rolling speed is sufficiently high and zero,
k: deformation resistance, k ₀ : asymptotic value of deformation resistance asymptotically increasing with increasing rolling speed,
k ₁ : difference in deformation resistance when the rolling speed is sufficiently high and zero,
V: rolling speed, a, b: speed dependence coefficient A method for controlling the tension of a rolled material rolled by a cold rolling mill provided with one or more rolling stands,
The friction coefficient between the rolling roll and the rolled material of the rolling stand and the deformation resistance of the rolled material depend on the rolling speed, and then calculate the relationship between the rolling speed and the tension between the stands,
A tension control method for a cold rolling mill, wherein the peripheral speed of the rolling roll is controlled based on the calculated relationship between the rolling speed and the tension between stands. The friction coefficient and the deformation resistance of the rolled material depend on the rolling speed as shown in equations (1) and (2), and the rolling load during acceleration / deceleration is assumed to be constant. The tension control method for a cold rolling mill according to claim 3, wherein the relationship is calculated.

Where μ: friction coefficient, μ ₀ : asymptotic value of the friction coefficient asymptotically increasing with increasing rolling speed,
μ ₁ : Difference in friction coefficient between when the rolling speed is sufficiently high and zero,
k: deformation resistance, k ₀ : asymptotic value of deformation resistance asymptotically increasing with increasing rolling speed,
k ₁ : difference in deformation resistance when the rolling speed is sufficiently high and zero,
V: rolling speed, a, b: speed dependence coefficient

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