JP3120007B2 - Thickness control device for tandem cold rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem cold rolling mill for rolling steel or the like, and in particular, suppresses a thickness variation at the time of acceleration / deceleration, which remarkably appears when a rolling roll of a final stand is a dull roll. To a thickness control device.

[0002]

2. Description of the Related Art Dull rolling, in which a final stand is rolled using dull rolls, has a higher coefficient of friction between a roll and a metal material than bright rolling, which rolls using bright rolls. Very large. Therefore, even if the rolling opening of the final stand is operated, the rear tension of the final stand cannot be changed much,
It was difficult to accurately control the final thickness to a target value. Therefore, the plate thickness control device shown in FIG. 4 has been used.

In FIG. 4, a metal material 1 to be tandem cold-rolled is sequentially rolled by an n-2 stand rolling mill 2, an n-1 stand rolling mill 3 and an n stand rolling mill 4, and wound on a tension reel 5. Can be n-1 to n-
Between the two stands, a tensiometer between n-1 and n-2 stands 6
Is provided. In addition, n-
A one-stand output thickness gauge 7 is provided, and an n-stand output thickness gauge 8 is provided between the tension reels 5 and n stands.

Accordingly, the tension t-1 between the stands n-1 and n-2 detected by the tension meter 6 between the stands n-1 and n-2.
_n-1 is added to the n-1 stand opening correction amount calculating means 10. The n-1 stand opening correction amount calculating means 10 compares the rolling opening correction amount ΔS _n-1 with a tension reference calculated in advance by a process computer (not shown) as a host computer to reduce the deviation of the tension to zero. Is calculated and added to the (n-1) stand pressure reduction opening control means 11. The n-1 stand rolling opening control means 11 corrects the rolling opening reference calculated in advance with the rolling opening correction amount ΔS _n-1 , and according to the corrected rolling opening reference, the n-1 stand rolling mill 3 Controls roll opening.

On the other hand, an n-stand output side thickness gauge 8 detects an n-stand output side thickness h _xn and adds the thickness to the n-stand feedback thickness correction amount calculating means 9. The n-stand feedback thickness correction amount calculating means 9 calculates a correction amount Δh _cn-1 of the exit side thickness of the (n-1) -th stand for making the deviation zero by comparing with a previously calculated thickness reference. It is added to the n-1 stand feedback speed correction amount calculating means 12. Also, n
The -1 stand exit side thickness gauge 7 detects the exit side thickness h _xn-1 of the n-1 stand and adds it to the n-1 stand feedback speed correction amount calculating means 12.

The n-1 stand feedback speed correction amount calculating means 12 corrects the pre-calculated reference plate thickness at the exit side of the n-1 stand by the correction amount Δh _cn-1 , and calculates the corrected plate thickness reference and the plate thickness. _N- for making the difference from the detected value h _xn-1 zero
The speed correction amount ΔV _n−2 for two stands is calculated and added to the n−2 stand speed control means 13. The n-2 stand speed control means 13 corrects the speed reference of the n-2 stand calculated in advance by the speed correction amount ΔV _n-2 and controls the speed of the n-2 stand according to the corrected speed reference.

Thus, the conventional plate thickness control device corrects the speed of the n-2 stand so as to absorb any change in the outlet plate thickness of the n stand and the n-1 stand. When the tension between the n-1 and n-2 stands changes, the rolling opening of the n-1 stand rolling mill 3 is corrected so as to absorb the change.

[0008]

In the conventional thickness control apparatus described above, the output side thickness of the last n stands is compared with its reference value, and the n-2 stand is controlled so that the difference becomes zero. Since the roll speed is corrected, there is a problem that the control is delayed with respect to the thickness variation on the exit side of the final stand due to the variation of the friction coefficient during acceleration / deceleration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a thickness control apparatus for a tandem cold rolling mill capable of suppressing a thickness variation on the exit side of a final stand due to a change in speed of a rolling line. The purpose is to obtain.

[0010]

According to a first aspect of the present invention, there is provided a sheet thickness control device for a tandem cold rolling mill, wherein the final stand of the tandem cold rolling mill is n stands, and the upstream stand is n-th stand.
One stand and an upstream stand are referred to as an n-2 stand. The reference values of the speed of each stand, the exit side plate thickness, and the acceleration / deceleration rate are calculated in advance by a host computer. The relationship between the stand-side exit thickness correction amount of one stand and the reference thickness and the stored value is controlled, and the n-stand and n-1 are controlled.
Outgoing plate thickness detecting means for detecting each outgoing plate thickness of the stand,
a first thickness correction amount calculating means for calculating a difference between a reference value and a detection value of the output side plate thickness of the n-th stand, and calculating a correction amount of the output side plate thickness of the (n-1) th stand to make the difference zero; And n
Based on the speed reference of the stand and the stored exit thickness correction amount, the exit thickness correction amount of the (n-1) th stand for correcting the variation of the exit thickness of the n-stand during acceleration / deceleration is calculated.
Second sheet thickness correction amount calculating means for outputting when the corresponding rolled material position reaches the n-1 stand, and correction of each delivery side sheet thickness calculated by the first and second sheet thickness correction amount calculating means. The output thickness reference of the n-1 stand is corrected according to the amount, and the difference between the corrected output thickness reference and the output thickness detection value of the n-1 stand by the output thickness detection means is set to zero. Speed correction amount calculating means for calculating the speed correction amount of the two stands;
speed correction means for correcting the speed reference of the n-2 stand by the speed correction amount calculated by the speed correction amount calculation means, and controlling the speed of the n-2 stand in accordance with the corrected speed reference.

According to a second aspect of the present invention, in the tandem cold rolling mill according to the second aspect, the host computer further comprises: n-1 to n-2.
When calculating respective reference values of the tension between the stands and the rolling opening of the n-1 stand, tension detecting means for detecting the tension between the n-1 to n-2 stands, and the n-1 to n-2 stands And an upper-level computer that calculates a difference between a reference value and a detected value of tension between the two, and calculates a correction amount of a rolling-down opening of an n-1 stand for making the difference zero. A rolling-down opening control means for correcting the corrected rolling-down opening reference by the speed correction amount calculated by the opening-correction-amount calculating means, and controlling the rolling-down opening of the n-1 stand according to the corrected rolling-down opening reference; It has.

[0012]

The operation of the present invention will be described below after describing the principle of the present invention. When the friction coefficient in cold rolling is μ,
When the rolling roll is a bright roll, there is a relationship shown in a curve B in FIG. 2 between the rolling speed V and the friction coefficient μ. That is, only in the low speed region, the friction coefficient μ decreases in inverse proportion to the increase in the speed, and in a region higher than this speed region, that is, a normal variable speed region, the friction coefficient μ shows a substantially constant value. However, when the rolling roll is a dull roll, there is a relationship shown by a curve D in FIG. 2 between the rolling speed V and the friction coefficient μ. That is, the friction coefficient μ changes not only in the low speed region but also in the normal variable speed region. Therefore, it has been found that the rolling load also changes in proportion to the change in the friction coefficient during the acceleration and deceleration of the dull rolling.

Generally, the rolling load can be represented by the following theoretical formula. P _n = f (H ₁ , H _n , h _n , q _fn , q _bn , k _n , μ _n , b) (1) where P _n : rolling load H ₁ : metal material material thickness H _n : stand entry side thickness h _n: stand delivery side thickness q _fn: forward tension q _bn: rear tension k _n: material deformation resistance mu _n: coefficient of friction b: width of material subscript n: respectively show n stand. As is apparent from the equation (1), the rolling load _Pn is represented as a function of each of the above-mentioned elements, and the friction coefficient μ is one of the elements.

[0014] Now, the following equation is obtained when to determine the amount of change in rolling load P _n associated with a change of the friction coefficient mu _n the equation (1) is partially differentiated by the coefficient of friction mu _n.

[0015]

(Equation 1) Thus, increment of the rolling load P _n for increment of the friction coefficient mu _n is expressed by the following equation.

ΔP _n = f ′ (H ₁ , H _n , h _n , q _fn , q _bn , k _n , μ _n , b) · Δμ _n (3) On the other hand, the exit side sheet thickness and the rolling in the cold rolling There is a relation between the load and the following equation.

[0017]

(Equation 2) However h _n: exit side thickness S _n: pressure opening P _n: rolling load M _n: Mill stiffness coefficient indices n: represents n stand respectively.

Thus, it can be seen that a change in the friction coefficient μ _n causes a change in the rolling load P _n , and that when the rolling load P _n changes, the plate thickness h _n changes. Therefore, in order to suppress the thickness variation due to the change in the friction coefficient in the dull rolling, the variation in the rolling speed is predicted, and in the direction of increasing the thickness h _n-1 on the exit side of the n-1 stand during acceleration, and during the deceleration. n-1 may be respectively corrected to reduce the plate thickness h _n-1 stand outlet side. The relationship between the speed change of the n stands and the exit side thickness correction amount of the n-1 stand for correcting the thickness change corresponding to the speed change is stored in the process computer.

In the sheet thickness control device for a tandem cold rolling mill according to the first aspect, the output side plate of the n-1 stand for reducing the difference between the reference value and the detected value of the output side thickness of the n stand to zero. Discharge thickness correction of the n-1 stand for correcting the variation of the discharge thickness of the n stand during acceleration / deceleration based on the thickness correction amount, the speed reference of the n stands, and the stored discharge thickness correction amount stored. At the time when the corresponding rolled material position reaches the n-1 stand, the speed / speed reference of the n-2 stand is corrected by feedforward based on these two exit side thickness correction amounts, and the correction is performed. Since the speed of the n-2 stand is controlled in accordance with the speed standard, it is possible to suppress a variation in the thickness of the final stand exit side due to a change in the speed of the rolling line.

According to a second aspect of the present invention, in the thickness control apparatus for a tandem cold rolling mill, the tension variation between the n-1 and n-2 stands caused by changing the speed of the n-2 stand is further reduced. , N−1 stand by correcting the rolling opening of the stand, it is possible to enhance the effect of suppressing the sheet thickness fluctuation on the exit side of the final stand due to the speed change of the rolling line.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the drawing, components denoted by the same reference numerals as those in FIG. 4 showing a conventional device indicate the same components. The difference from FIG. 4 is that an n-1 stand feed forward plate thickness correction amount calculating means 14 is newly added. The n-1 stand feed forward plate thickness correction amount calculating means 14 calculates the variation of the output plate thickness of the n stand during acceleration / deceleration based on the speed reference of the n stand and the output plate thickness correction amount stored in the process computer. The correction amount of the exit side thickness of the (n-1) th stand for correction is calculated, and is added to the (n-1) th stand feedback speed correction amount calculating means 12 when the corresponding rolled material position reaches the (n-1) th stand.

The operation of the present embodiment having the above-described configuration will be described below with a focus on portions having a configuration different from that of the conventional device. The n-1 stand feed forward plate thickness correction amount calculating means 14 calculates the material position at which the metal material is accelerated / decelerated immediately below the n stand by the schedule calculation of the process computer, and the acceleration / deceleration position is determined immediately below the n-1 stand. Is predicted at time t. Further, since the process computer stores the data of the correction amount of the exit side plate thickness of the n-1 stand with respect to the change in the roll peripheral speed of the n stand, the n-time is always n-according to the acceleration / deceleration rate of the rolling line by the schedule calculation. The output side thickness correction amount Δh _dn-1 of one stand is calculated. Then, the predicted time t
, The output side thickness correction amount Δh _{dn−1 is changed} to n−1
It is added to the stand feedback speed correction amount calculating means 12.

The n-1 stand feedback speed correction amount calculating means 12 calculates the output thickness h _{xn-1 of} the n-1 stand detected by the n-1 stand output thickness gauge 7, and the n stand feedback thickness correction amount. The correction amount Δh _cn-1 of the exit side plate thickness of the n-1 stand calculated by the means 9 and the n-th calculated by the n-1 stand feed forward plate thickness correction amount calculation means 14.
The thickness correction amount Δh _{dn-1 of} one stand and the _output side thickness reference h _{refn-1 of} the n-1 stand calculated by the process computer.
The following equation is calculated. Δh _n−1 = h _xn−1 −h _refn−1 + Δh _cn−1 + Δh _dn−1 (5) Next, the n−1 stand feedback speed correction amount calculation means 12 performs n A proportional integral calculation is performed on the output side plate thickness deviation Δh _{n−1 of the} −1st stand, and finally a speed correction amount ΔVn ₋₂ of the n−2 stand is calculated and transmitted to the n−2 stand speed control means 13. Add. Therefore, the n-2 stand speed control means 13 corrects the speed reference of the n-2 stand calculated in advance by the speed correction amount ΔV _n-2 and controls the speed of the n-2 stand according to the corrected speed reference. I do.

FIGS. 3A and 3B show n corresponding to these controls.
It is the diagram which showed the rolling speed _Vxn of a stand and the exit side board thickness _hxn-1 of an n-1 stand, and the relationship with time. That is, the rolling speed V _xn of the n stand is changed from the time t ₂ to the time t _3.
Until it accelerated at a constant acceleration, and was rolling schedule which is decelerated at a constant deceleration from time t ₅ to time t _7.
When such acceleration or deceleration is performed, a large period of speed with reduced friction coefficient mu _n, it is also reduced rolling load P _n. The reduction of the rolling load _Pn reduces the exit side plate thickness _hxn . To compensate for this decrease, the exit side thickness correction amount Δ of the n-1 stand
h _dn-1 is output in the feed-forward at time t _1. As a result, thickness at delivery side of the n-1 stand begins to increase at time t _1, further it begins to decrease at time t _4. Thus, the thickness increase area from time t ₁ to time t ₆ is takes time from time t ₁ to t ₂ (equivalent to the time from time t ₄ to t ₅₎ from n-1 Stand It reached n stands just period to increase the rolling speed of the n stand, i.e., between the time t ₂ to time t _7, n-1
The stand-out side plate thickness (the in-side plate thickness of the n-stand) is increased, whereby the decrease of the stand-out side plate thickness of the n-stand can be suppressed.

As apparent from the above description, according to this embodiment, when the metal material is rolled by the dull roll,
By estimating the thickness variation by feedforward, the thickness variation during acceleration / deceleration is suppressed.

In the above embodiment, the tension meter 6 between the n-1 and n-2 stands and the opening degree correction amount calculating means for the n-1 stand are used.
The plate thickness control device including the 10 and the n-1 stand roll-down opening degree control means 11 has been described. However, the plate thickness control device not including these elements can also be fed forward in the thickness change on the n-1 stand exit side. And a technique of correcting the speed reference of the n-2 stand so as to remove the fluctuation can be applied.

[0027]

As is apparent from the above description, according to the thickness control device for the tandem cold rolling mill according to the first aspect, the thickness variation on the exit side of the final stand due to the speed change of the rolling line can be prevented. Can be suppressed.

Further, according to the thickness control device of the tandem cold rolling mill according to the second aspect, the effect of suppressing the thickness variation on the exit side of the final stand due to the speed change of the rolling line can be enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a rolling speed and a friction coefficient in order to explain the principle of the present invention.

FIG. 3 is a diagram illustrating the operation of an embodiment of the present invention;
FIG. 4 is a diagram showing a relationship between a rolling speed V _xn of a stand and an exit side plate thickness h _xn-1 of an n-1 stand, and time.

FIG. 4 is a block diagram illustrating a configuration of a conventional thickness control device of a tandem cold rolling mill.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Metal material 2,3,4 Stand rolling mill 5 Tension reel 6 Tensiometer 7,8 Thickness gauge 9 nStand feedback thickness correction amount calculating means 10 n-1Stand opening correction amount calculating means 11 n-1 stand pressure reduction Opening degree control means 12 n-1 stand feedback speed correction amount calculation means 13 n-2 stand speed control means 14 n-1 stand feed forward plate thickness correction amount calculation means

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 37/16-37/20 B21B 37/48-37/52

Claims (2)

(57) [Claims] 1. The final stand of a tandem cold rolling mill is n stands, its upstream stand is n-1 stand, and its upstream stand is n-2 stand. Each reference value of the exit side plate thickness and the acceleration / deceleration rate is calculated, and the relationship between the speed change amount of the n-th stand and the exit side plate thickness correction amount of the (n-1) th stand is stored, and based on these reference values and the stored values. A thickness control device for a tandem cold rolling mill for controlling a thickness of a sheet, comprising an output thickness detection means for detecting each output thickness of an n stand and an n-1 stand, and a reference value of an output thickness of the n stand. and it calculates the difference between the detected value, the first plate thickness correction amount for calculating the correction amount of output side thickness of the n-1 stands for the difference to zero
A calculating means, and a correction amount of the outlet thickness of the (n-1) -th stand for correcting a variation of the outlet thickness of the n-stand during acceleration / deceleration based on the speed reference of the n-stand and the stored correction amount of the outlet thickness. And a second thickness correction amount calculating means for outputting when the corresponding rolled material position reaches the n-1 stand, and the first and second thickness correction amount calculating means . The outlet thickness reference of the n-1 stand is corrected based on the calculated correction amount of each outlet thickness, and the corrected outlet thickness reference and the outlet thickness detection value of the n-1 stand by the outlet thickness detecting means are corrected. a speed correction quantity calculating means for calculating the speed correction amount of n-2 stand for the zero difference of the speed reference of the n-2 stand corrected by the speed correction amount calculated in the speed correction amount calculation means Controls the speed of the n-2 stand according to the corrected speed reference Tandem cold rolling mill of plate thickness controller having a speed control means that. 2. The system according to claim 1, wherein said host computer further comprises n-1 to n-
When calculating respective reference values of the tension between the two stands and the rolling opening of the n-1 stand, tension detecting means for detecting the tension between the n-1 and n-2 stands, and n-1 to n-2 An opening correction amount calculating means for calculating a difference between a reference value of the tension between the stands and a detected value, and calculating a correction amount of the rolling-down opening of the (n-1) stand for reducing the difference to zero; in pressure opening the computed pressure opening reference is corrected by opening degree correction amount calculated by the opening correction amount calculating means, controlling the n-1 stand reduction opening accordance with the corrected pressure opening reference The thickness control device for a tandem cold rolling mill according to claim 1, further comprising control means.