KR101322988B1 - Rolling mill having controller for shape of rolling plate and controlling method thereof - Google Patents

Abstract

(단,

: 후단 스탠드의 벤더력 변동분,

: 전단 스탠드의 벤더력 변동,

: 후단 스탠드에서의 출측두께,

: 전단 스탠드에서의 출측두께)
본 발명에 따르면 압연기를 구성하는 각 스탠드 각각에 형상 측정장치를 구비하지 않고도, 각 스탠드 별 벤더력 변동분을 고려한 제어가 가능하다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling mill with a shape control device and a control method thereof, wherein the rolling mill with a shape control device according to the present invention includes a plurality of stands, shape measuring units, bender force correction means, and bender force control means. The stand performs the irreversible continuous rolling process according to the predetermined bender force, respectively, and is provided in plurality. The shape measuring unit is provided on at least one exit side of the plurality of stands to measure flatness. The bender force correction means calculates the change in the bender force of the stand provided with the shape measurement part from the flatness measured by the shape measurement part, and calculates the change in the bender force for each stand which follows the following formula (1). The vendor force control means controls each stand by reflecting the calculated variation of the vendor force on the predetermined vendor force.
<Formula 1>

(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand)
According to the present invention, it is possible to control in consideration of the change in the bender force for each stand without providing a shape measuring device in each stand constituting the rolling mill.

Description

Rolling mill having controller for shape of rolling plate and controlling method

The present invention relates to a rolling mill having a shape control device and a control method thereof, and more particularly, to a shape control method of a rolled material and a device for minimizing flatness error caused by temperature variation of a material in an irreversible rolling mill. It relates to a rolling mill provided.

Roll bending refers to bending a roll by applying a force from the outside to both ends of the roll in order to control the smoothness or the shape of the cross section of the rolled sheet and to roll out a sheet having a uniform thickness over the roll width. Rolling of a single product may be a fixed crown, but if the material has a hard and soft part, the desired cross section cannot be obtained with a single crown, and thus a roll bending or roll cushioning method is employed.

Conventional plate control technology is based on bender force control and additional roll axis movement and roll cooling system are used, but roll cooling is not easy to apply because of slow response. In addition, axial movement of the roll is not easy in real time in terms of rolling stability. Although various mechanisms for controlling the shape are known as patents, it is known that there are few technologies that are actually used and their effectiveness is not great.

When cold rolling stainless steel using a continuous rolling mill, the material undergoes a hot rolling process in advance. At this time, there is a crown deviation in the tip and tail end of the material according to the temperature deviation caused by hot rolling. For this reason, even in the cold rolling, even if the bender force setting is optimal, flatness error due to the crown deviation of the tip and tail ends occurs. Therefore, there is a need for a high precision flatness control method considering the longitudinal crown variation of the entrance material. However, there are various techniques to reduce the flatness error, but mainly the shape control for the reverse rolling mill (reversible), the shape control in the continuous rolling mill does not reflect the fluctuation of the crown. In order to control the flatness in the continuous rolling mill, there may be a method using a shape measuring device for measuring the flatness of the rolling material in each rolling stand. However, since the shape measuring instrument is relatively expensive, it is difficult to equip all the stands. Therefore, in the stand without a shape measuring machine, the bender force is determined by the bender force set value set at the beginning of rolling, and the correction is not performed according to the longitudinal crown deviation of the material during the rolling operation. In a continuous rolling mill (non-reversible), such a correction must be provided with an expensive shape measuring device as described above in order to be made in real time or periodically.

An object of the present invention is to provide a method and means capable of controlling the shape according to the change in the bender force for each stand in consideration of the crown variation of the rolled material through a small number of shape measuring apparatus when rolling stainless steel in a continuous rolling mill.

Another object of the present invention is to provide a method and means for improving the flatness hit ratio in the longitudinal direction of a rolled material through such a shape control method.

The rolling mill provided with the shape control apparatus which concerns on this invention contains a some stand, a shape measuring part, a bender force correction means, and a bender force control means.

The stand performs the irreversible continuous rolling process according to the predetermined bender force, respectively, and is provided in plurality.

The shape measuring unit is provided on at least one exit side of the plurality of stands to measure flatness.

The bender force correction means calculates the change in the bender force of the stand provided with the shape measurement part from the flatness measured by the shape measurement part, and calculates the change in the bender force for each stand which follows the following formula (1).

<Formula 1>

: 후단 스탠드의 벤더력 변동분,

: 전단 스탠드의 벤더력 변동,

: 후단 스탠드에서의 출측두께,

: 전단 스탠드에서의 출측두께)(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand)

The vendor force control means controls each stand by reflecting the calculated variation of the vendor force on the predetermined vendor force.

In addition, the plurality of stands may perform a cold rolling process.

In addition, the flatness measurement by the shape measurement unit, the calculation of the change in the bender force by the bender force correction means and the stand control reflecting the change in the bender force by the bender force control means may be periodically performed.

In addition, the shape measurement unit may be provided at the stand exit side of the foremost of the plurality of stands.

In addition, at least four stands may be provided.

On the other hand, in the method for controlling the plurality of stands for performing the irreversible continuous rolling process according to the change in the bender force, the shape control method according to the present invention includes the following steps.

In the first step, the flatness is measured at one stand exit side of the plurality of stands.

In the second step, the change in the bender force of the stand for measuring the flatness is calculated from the measured flatness.

In the third step, the change in the bender force for each stand at the rear end of the stand for flatness measurement is sequentially calculated by the following Equation 1.

<Formula 1>

: 후단 스탠드의 벤더력 변동분,

: 전단 스탠드의 벤더력 변동,

: 후단 스탠드에서의 출측두께,

: 전단 스탠드에서의 출측두께)(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand)

In the fourth step, the vendor force of each stand is readjusted in consideration of the calculated variation in the vendor force for each stand.

In addition, in the first step, the exit flatness of the stands at the foremost stage among the plurality of stands may be measured.

In addition, the method may further include a fifth step of periodically performing the first to fourth steps.

According to the present invention, it is possible to control in consideration of the change in the bender force for each stand without providing a shape measuring device in each stand constituting the rolling mill.

In addition, according to the present invention, it is possible to obtain an effect that the hit ratio to the flatness is significantly improved compared to the rolling mill without the shape control method.

1 is a schematic view showing a state of a rolling mill according to an embodiment.
2 is a block diagram showing a state of a rolling mill according to an embodiment.
3 is a flowchart illustrating a shape control process according to an exemplary embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the absence of special definitions or references, the terms used in this description are based on the conditions indicated in the drawings. The same reference numerals denote the same members throughout the embodiments. For the sake of convenience, the thicknesses and dimensions of the structures shown in the drawings may be exaggerated, and they do not mean that the dimensions and the proportions of the structures should be actually set.

1 and 2 will be described a rolling mill having a shape control apparatus according to an embodiment of the present invention. 1 is a schematic diagram showing a state of a rolling mill according to an embodiment, and FIG. 2 is a block diagram illustrating a state of a rolling mill according to an embodiment.

The rolling mill 100 includes first to fourth stands 101, 102, 103, 104, first and second shape measuring parts 201 and 202, bender force correction means and bender force control means.

The rolling mill according to this embodiment is an irreversible continuous rolling mill (continuous rolling mill) and includes first to fourth stands 101, 102, 103, 104. In the rolling process, the strip 10 first passes through the first stand 101 and then continuously passes through the second, third and fourth stands 102, 103, 104 to perform the rolling process. At this time, rolling is performed in each stand according to the set reduction ratio. The strip 10 is wound into the coil 400 at the rear end of the rolling mill after the rolling process is finished via the first to fourth stands 101, 102, 103, 104. On the other hand, in the present embodiment, but having a total of four stands is not limited to this, the present invention can be equally applied to a rolling mill having four or more stands.

The first shape measuring part 201 is provided at the exit side of the first stand 101. The first shape measuring unit 201 measures the flatness of the strip 10 that is provided on the exit side of the first stand 101. That is, the first shape measuring unit 201 is a kind of measuring instrument having a plurality of measuring points in the width direction of the strip 10, and calculates the crown amount after detecting the plate thickness distribution in the plate width direction. The first shape measuring unit 201 according to the present embodiment measures the flatness in the strip width direction periodically 10 times or more, preferably 20 times or more, as the strip 10 moves along the rolling process. The measured flatness data is transmitted to the bender force correction means 220 which will be described later.

In addition, the flatness measured by the 1st shape measuring part 201 in this embodiment is used in order to calculate the change of the bender force of each following stand as mentioned later. Therefore, it is preferable that the first shape measuring part 201 is provided at the stand exit side of the foremost stage among the stands provided in the first stand 101, that is, the rolling mill 100.

On the other hand, in addition to the second shape measuring unit 202 may be provided. The second shape measuring unit 202 is provided at the fourth stand 104 exit side. However, the second shape measurement unit 202 may be provided for comparison with the change in the bender force required in accordance with the present invention to be described later or more accurate calculation of the change in the bender force. Accordingly, the second shape measuring unit 202 may be provided on any one or two or more of the second to fourth stands 102, 103, 104. However, since the shape measuring unit corresponds to a relatively expensive device, it is advantageous to minimize the number of the provided.

The bender force correction means 220 receives the flatness data from the first shape measuring unit 201 and calculates the change in the bender force to control the first to fourth bender force controls to control the respective stands 101, 102, 103, and 104. Function to convey to the means 301, 302, 303, 304.

However, the change in the bender force calculated by the bender force correction means 220 includes two variations in the bender force for the first stand 101 and a change in the bender force for the second to third stands 102, 103, and 104. Are distinguished.

First, the change in the bender force for the first stand 101 may be directly calculated using the flatness data transmitted from the first shape measurement unit 201 using a conventional bender force setting value calculation module for shape control. That is, when the flatness of the strip 10 is measured from the first shape measurement part 201, the bender force required to obtain the target crown and the flat shape is calculated directly according to the flatness. Thickness distribution of the plate width direction is mainly controlled by the bending force (bending force) of the steel plate width direction applied to the work roll of each stand, and the case of controlling the cross angle by crossing the upper and lower rolls.

Next, the change in the bender force transmitted to each of the second to fourth bender force control means 302, 303, 304 to control the second to fourth stand 102, 103, 104 directly affects the flatness of each stand. It calculates from the change of the bender force with respect to the 1st stand 101 mentioned above without measuring. Hereinafter, a process of deriving an equation for calculating a change in vendor force for each of the second to fourth stands 102, 103, and 104 will be described.

First, the relationship between the flatness and the plate crown can be expressed by the following formula (1).

(Equation 1)

: 평탄도(판형상),

: 입측크라운,

: 출측크라운,

: 입측 소재두께,

: 출측 소재두께,

: 상수)(only,

: Flatness (plate shape),

: Crown crown,

: Crown,

: Side material thickness,

: Material thickness of exiting

: a constant)

Subsequently, Equation 1 is summarized by applying the perturbation method in order to consider the fluctuation in the longitudinal direction of the material, that is, the fluctuation of the crown and the flatness of the stand and exit of the stand together.

(Equation 2)

: 판형상 변동,

: 입측크라운 변동,

: 출측크라운 변동)(only,

: Plate shape variation,

: Change in crown crown,

: Change in crown

Next, the feedback control and the automatic plate thickness control (AGC) using the flatness measured from the first shape measuring unit 201 provided at the exit side of the first stand 101 with respect to the longitudinal crown fluctuation of the entry material. Equation 2 can be summarized as Equation 3 assuming that the thickness control performance can be achieved.

(Equation 3)

On the other hand, it can be derived from Equation 3 to the equation representing the exit crown variation in accordance with the flatness control for the entry crown variation.

(Equation 4)

: 벤더력,

: 벤더력 변동치,

: 벤더력 초기치)(only,

Bender power,

: Change in vendor power,

: Bender initial value)

From the above Equation 4, the change in the bender force at the next stand after the first stand 101 can be predicted as shown in Equation 5 in consideration of the outward crown fluctuation with respect to the entrance crown fluctuation and the bender force fluctuation for the flatness control thereof. .

(Equation 5)

: 후단 스탠드의 벤더력 변동,

: 전단 스탠드의 벤더력 변동,

: 후단 스탠드 출측두께,

: 전단 스탠드 출측두께)(only,

: Bender power fluctuation of rear stand,

: Bender force fluctuation of shear stand,

: Rear stand exit thickness,

: Shear stand exit thickness)

That is, when the change in the bender force of any one stand is known, the change in the bender force of the trailing stand adjacent to the stand can be calculated from Equation 5 above. In addition, it is possible to continuously calculate the change in the bender force for the following multiple stands in the same way. In this embodiment, the control amount for each stand for shape control has the following relationship.

: i번째 스탠드 벤더력 변동분(i=1~4),

: i번째 스탠드 벤더력 설정치(i=1~4),

: i번째 스탠드 출측두께(i=1~4))(only,

: i-th stand bender change (i = 1-4),

i th stand bender setting value (i = 1 ~ 4),

: i-th stand exit thickness (i = 1 ~ 4)

When the flatness of the first stand 101 is measured through the first shape measuring unit 201 as described above, and the fluctuated bender force or the change in the bender force of the first stand 101 is calculated, It is possible to continuously calculate the change in the bender force required for the control of each stand. In addition, the bender force correction means 220 is a variable bender force of the first stand 101 and the second to fourth stands 102, 103, 104 according to the period in which the first shape measurement unit 201 measures the flatness. ) Will calculate the change in the bender power.

On the other hand, the first to fourth bender force control means (301, 302, 303, 304) is the first to fourth bender force setting value in consideration of the bender force correction value calculated by the above-described bender force correction means 220 The fourth stand 101, 102, 103, 104 is controlled. The first to fourth bender force control means (301, 302, 303, 304) are each in accordance with a cycle in which the fluctuating bender force for each stand is calculated by the first shape measuring unit 201 and the bender force correcting means 220. It will control the bender power of the stand.

2 and 3, a shape control process during cold rolling according to the present invention will be described. 3 is a flowchart illustrating a shape control process according to an exemplary embodiment.

The stainless steel material that has undergone the hot rolling process, that is, the strip 10 has a crown at the leading end and the trailing end of the strip 10 due to the material temperature variation occurring in the hot rolling process, and the tip of the strip 10 is formed by the crown. Flatness errors occur at the ends. In order to correct the flatness error, first, in the first step, the flatness is measured through the first shape measuring unit 201 at the exit side of the first stand 101 (S10).

에 의하여 후단의 각 스탠드별 벤더력 변동분을 순차적으로 산출한다.(S30)In addition, in the second step, the change in the bender force of the first stand 101 is calculated from the measured flatness. (S20) Subsequently, in the third step, Equation 5, namely,

By this, the change in the bender force for each stand in the rear stage is sequentially calculated. (S30)

: 후단 스탠드의 벤더력 변동분,

: 전단 스탠드의 벤더력 변동,

: 후단 스탠드에서의 출측두께,

: 전단 스탠드에서의 출측두께)(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand)

Subsequently, in the fourth step, the bender force of each stand is readjusted in consideration of the calculated variation in the bender force for each stand. (S40) The shape control process of the first step S10 to the fourth step S40 is performed per second. 10 or more times, preferably 20 or more times.

Thus, the bender force correction by the flatness measurement of the 1st stand 101, and the bender of the 2nd stand 102 thru | or the 4th stand 104 by said formula 5 from the change of the bender force of the 1st stand 101 By periodically calculating the force variation, it is possible to correct the flatness error occurring in the longitudinal direction of the strip in real time.

Although the preferred embodiments of the present invention have been described above, the technical idea of the present invention is not limited to the above-described preferred embodiments, and various shape control apparatuses are provided within the scope not departing from the technical idea of the present invention specified in the claims. It can be implemented with a rolling mill and its control method.

100: rolling mill (irreversible continuous rolling mill)
101, 102, 103, 104: first to fourth stands
201 and 202: first and second shape measuring sections
210: bender force setting means 220: bender force correction means
301, 302, 303, 304: first to fourth bender force control means

Claims (8)

A plurality of stands each performing an irreversible continuous rolling process in accordance with a predetermined bender force;
A shape measuring unit provided on at least one exit side of the plurality of stands to measure flatness of the strip;
By using the correlation between the flatness measured by the shape measuring part and the crown fluctuations at the entrance and exit sides of the stand provided with the shape measuring part, the change in the bender force of the stand with the shape measuring part is obtained. Bender force correction means for calculating and calculating a change in the bender force for each stand which is followed by Equation 1 below; And
And a bender force control means for controlling each stand by reflecting the calculated bender force variation to the predetermined bender force.
<Formula 1>

(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand) The method of claim 1,
The plurality of stands are provided with a shape control device for performing a cold rolling process. The method of claim 1,
And a shape control device for periodically measuring the flatness by the shape measuring unit, calculating the change in the bender force by the bender force correction means, and the stand control reflecting the change in the bender force by the bender force control means. The method of claim 1,
And the shape measuring part is provided with a shape control device which is provided at the stand exit side of the foremost end of the plurality of stands. The method of claim 1,
Rolling mill having a shape control device provided with at least four stands. A method of controlling a plurality of stands for performing an irreversible continuous rolling process according to a change in bender force,
A first step of measuring flatness of the strip at one of the stand exits of the plurality of stands;
Calculating a change in the bender force of the flatness measurement target stand for obtaining the flatness of the strip by using the correlation between the measured flatness and the crown variation of the entrance and exit sides of the flatness measurement target stand;
A third step of sequentially calculating a change in bender force for each stand at the rear end of the stand for flatness measurement according to Equation 1 below; And
And a fourth step of readjusting the bender force of each stand in consideration of the calculated change in the bender force for each stand.
<Formula 1>

(only,

: Bender power change of rear stage stands,

: Bender force fluctuation of shear stand,

: Exit thickness at rear end stand,

: Exit thickness at shear stand) The method according to claim 6,
In the first step, the shape control method for measuring the exit flatness of the stand at the foremost of the plurality of stands. The method according to claim 6,
And a fifth step of periodically performing the first to fourth steps.

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