JP3274398B2 - Work roll initial crown determination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining an initial crown of a work roll for obtaining a steel plate having a small plate crown.

[0002]

2. Description of the Related Art As a method of reducing a sheet crown,
There are a roll mechanism such as a work roll shift mechanism, a roll cross mechanism and a bender mechanism, and a roll mechanism. The former (based on the rolling mechanism) can change the mechanical crown of the roll for each rolled material, so that it is very effective, but has a problem that the equipment cost increases.

As the latter method (depending on the roll shape), there are a method of rolling by combining a large backup crown and a concave work roll crown, and a method of rolling by giving a special shape convex crown to a work roll. . However, in the latter method, in rolling at roll chance, a roll profile including a wear crown and a thermal crown greatly changes for each rolled material, and the knitting of the size of the rolled material differs for each roll chance. Therefore, there is a problem that the effectiveness cannot be exhibited unless the initial crown amount of the roll is appropriate at the roll chance.

Therefore, conventionally, the initial crown of the roll has been empirically determined according to the amount of wear of the backup roll.

[0005]

However, according to the above-mentioned empirically determined method, the determined value varies depending on the skill level of the operator and the like, and it is not possible to appropriately cope with various roll knitting, and one roll chance is not obtained. In some cases, there is a possibility that a rolled material that cannot achieve the target plate crown may occur. Accordingly, an object of the present invention is to provide a method for determining an initial crown of a work roll capable of stably achieving a target plate crown with respect to all rolled materials regardless of slab knitting of one roll chance. Things.

[0006]

In order to achieve the above object, the present invention takes the following measures. That is, the first invention is characterized in that the roll crown is reflected, the target plate thickness and the plate crown are secured, and the work roll is initialized using a pass schedule setting method in consideration of the shape dead zone region. A method for determining a crown, based on a predetermined rolling order in one roll chance after the work roll replacement after the next replacement, predict the wear crown of the work roll at the time of each slab rolling, and thermal crown, The roll crown of the work roll at the time of each slab rolling is obtained by adding a preset initial crown to these predicted values, and the target plate crown is secured by using the pass schedule setting method under the obtained roll crown. It is determined whether or not the initial crown can be obtained so that the number of slabs satisfying the target plate crown is maximized. To the point you want to change certain.

A pass schedule setting method that reflects the roll crown, secures the target sheet thickness and sheet crown, and considers the shape dead zone region is performed by calculating the delivery side sheet thickness by a rolling load prediction model formula, and by the following formula. The output side crown is obtained by the given sheet crown prediction model formula,

[0008]

[Number 2] _{C h = f (C W,} C B, B, P, h, H, C H, R W, R B) ...... (1) _{where, C W = C I + C} T + C E ...... (2) C _h: delivery side crown C _W: roll crown C _B of the work rolls: amount of wear of the backup rolls B: strip width P: rolling load h: exit side thickness H: thickness at entrance side C _H: entry side crown R _W: the radius R _B of the work rolls: backup roll radius C _I: initial crown C _T: thermal crown C _E: abrasion crown the side plate crown leaving the target delivery side crown on the last pass by dividing the target delivery side thickness Calculate the ratio of the entrance side plate crown in the final pass using the prediction model formula based on the calculated value, and calculate the plate crown ratio change obtained as the difference between these two plate crown ratios. Crown ratio change is in the shape dead zone Thus, the rolling load and the exit side plate thickness are determined.

A second feature of the present invention is that a work schedule is set using a pass schedule setting method that reflects a roll crown, secures a target plate thickness and a plate crown, and takes a shape dead zone region into consideration. A method of determining an initial crown of a roll, comprising predicting a thermal crown of a work roll at the time of each slab rolling, based on a predetermined rolling order in one roll chance after a work roll replacement and a next replacement. The roll crown of the work roll at the time of each slab rolling is obtained by adding a preset initial crown to the predicted value, and the target plate crown can be secured using the pass schedule setting method under the obtained roll crown. Is determined, and the initial crown is changed so that the number of slabs satisfying the target plate crown is maximized. There is a point.

At the time of actual rolling, the initial crown determined by the above method is secured.
Grind the roll during rolling.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted a simulation analysis of the formation of a thermal crown at one roll chance in a thick plate rolling in which the rolling size fluctuates greatly from one roll to another, and have conducted an actual survey. Obtained. (1) Even in a roll having a diameter of 1 m for plate rolling, the thermal crown is 0.1 to 0.6 mm depending on rolling conditions (rolling size, number of passes, rolling temperature, roll cooling water amount, etc.).
It fluctuates greatly with the degree. (2) The amount of thermal crown differs for each roll chance,
The difference is about 0.2 mm on average for one roll.

From the above findings, it can be seen that in determining the initial crown, it is necessary to predict a roll profile including a thermal profile for each roll chance. Therefore, the initial crown is determined according to the following procedure. (A) The wear profile and the thermal profile of the work roll at the time of each slab rolling are predicted in a predetermined rolling order, and the initial crown of the work roll (any predetermined temporary value (experience value) ).Less than,
"Initial initial crown" is added to obtain a work roll profile (crown) at each slab rolling.

The shape of the initial crown is not particularly limited. That is, since the path is set in consideration of the initial profile of the sine curve or the composite composite curve (spline curve) as described later, there is no problem in determining the initial crown. (B) From the predicted work roll profile, it is determined whether or not the target plate crown can be satisfied for all rolled materials within one roll chance.

The discrimination is performed using a pass schedule setting method that reflects a roll profile (crown), secures a target plate thickness and a plate crown, and considers a shape dead zone region. As the path schedule setting method, for example, JP-A-7-178424, JP-A-9-57
The method described in JP-A-316 is used. That is, the pass schedule of the thick plate rolling is determined by the following procedures in order to sequentially set the “shape adjustment pass”, the “joining pass”, and the “maximum milling pass” in a manner reverse to the target plate thickness. I do.

[0015] Based on the (side plate crown C _h out the final pass) target thickness given (delivery side thickness of the final pass h) between the target strip crown, the final pass out of the side plate crown ratio (C _h
/ H) and the rolling load of the final pass is set. According to the rolling load prediction model formula given separately,
The thickness H on the incoming side of the final pass, that is, the thickness h on the outgoing side of the pass immediately before the final pass (hereinafter, this pass is referred to as “the pass”) is determined.

According to a separately provided plate crown prediction model formula, the input side plate crown C _H of the final pass, that is,
Determine the side plate crown C _h out of "the path". From these values, the entrance side plate crown ratio of the final pass, that is, the exit side plate crown ratio of the "pass" is obtained. The change in the sheet crown ratio (C _h / h−C _H) obtained as the difference between the exit side sheet crown ratio of the “final pass” and the “pass”
/ H) determines the rolling load and the exit side plate thickness of the “pass” so that the predetermined setting value γ of the shape dead zone is satisfied.

However, | _Ch / h− _CH / H | ≦ γ (3) Shape dead zone: A region in which no wave is generated even if a change in the crown ratio of the plate is repeated. The rolling load and the exit side plate thickness of the pass just before are determined. (The path for determining the rolling load and the exit side plate thickness in this manner is referred to as a "shape adjustment pass.") When the rolling load of the shape adjusting pass exceeds the allowable maximum rolling load of the rolling mill, the above operations are stopped. And
By replacing the rolling load of the shape adjustment pass with the allowable maximum rolling load (the outlet sheet thickness is unchanged), the outlet sheet thickness and the rolling load are determined. (The path determined in this manner is referred to as a “joining path”.) In the subsequent paths, the allowable rolling load or allowable rolling torque of the rolling mill is calculated based on the rolling load prediction model formula and the rolling torque prediction model formula given separately. The rolling load and the exit side plate thickness are determined so as to satisfy the stricter restrictions of (1). (The path determined in this manner is referred to as a “mill capacity maximum path”.) The following equation reflecting the work roll crown is used in the “plate crown prediction model equation”.

[0018]

C _h = f (C _W , C _B , B, P, h, H, C _H , R _W , R _B ) (1) where C _W = C _I + C _T + C _E. (2) C _h: delivery side crown C _W: roll crown C _B of the work rolls: amount of wear of the backup rolls B: strip width P: rolling load h: exit side thickness H: thickness at entrance side C _H: entry side crown R _W: the radius R _B of the work rolls: backup roll radius C _I: initial crown C _T: thermal crown C _E: using the wear crown the pass schedule setting method, a roll profile (initial initial crown predicted for all the rolling material The determination as to whether or not the target plate crown can be satisfied with the roll crown under the following condition is performed as follows.

That is, the target plate crown is determined for each rolling size, and upper and lower limits are set for the finished load of the rolled material due to the limitation of the rolling mill capacity and the number of passes. If the predicted roll crown is too large, the roll must be greatly bent or the finished load must be increased to satisfy the target plate crown. Conversely, if the roll crown is too small, the roll cannot be flexed too much and the finished load must be reduced. Therefore, it is determined whether or not the target plate crown can be satisfied by determining whether the finished load for satisfying the target plate crown is within the upper and lower limit values. (C) The operations (a) and (b) are performed for each slab within the roll chance, and the initial initial crown of the work roll is changed so that the number of slabs that can secure the target plate crown is maximized.

The thermal profile (crown) was newly derived from the solution of the two-dimensional heat conduction equation in consideration of the body length and the heat flow in the radial direction as shown in the following equation (4).

[0021]

(Equation 4)

As shown in FIG. 1, the predicted value obtained by the above equation (4) shows a very good correspondence with the measured thermal crown amount at the roll center and at the roll position corresponding to the -100 mm end of the plate edge. It turns out that the thermal profile prediction by the equation is sufficient. Also, the wear profile prediction of the work roll can be accurately estimated by the following equation (5) incorporating the influence of the backup roll as shown in FIG.

[0023]

(Equation 5)

In a rolling mill having a device capable of grinding a roll during rolling, it is not necessary to predict the wear profile when determining the initial crown, and the initial crown is determined by considering only the thermal profile. Then, the wear profile may be predicted during actual rolling, and grinding may be performed to secure the initial crown. Since the wear can be predicted during actual rolling, the prediction accuracy is higher than the former.

As a device for grinding a roll during rolling, for example, an abrasive is ejected from an ejection nozzle at a high pressure and a high speed.
There is one that moves in the roll body length direction to grind the roll body length portion.

[0026]

FIG. 4 shows a slab knitting (rolling width and product thickness) at a certain roll chance 1, a thermal crown predicted at the time of rolling, and a corrected plate crown and a target plate when a pass schedule is set. This shows the amount of deviation from the crown. Corrected sheet crown is when the rolled material does not meet the target sheet crown in the roll profile.
This is the value when the target plate crown is corrected so that the finished load falls within the upper and lower limits.

In predicting the thermal crown, the number of passes, rolling temperature, and rolling pitch of each rolled material are determined in advance according to the size of the rolled material, the finishing temperature, and the like. When the pass schedule was set for each rolled material based on the thermal crown, the initial crown was determined so that the number of slabs that could secure the target plate crown was the largest. As a result, when actual rolling was performed, a pass setting that satisfies the target plate crown was achieved for most of the rolled materials.

FIG. 5 shows the slab knitting (rolling width, rolling width, and the like) when rolling is performed using the same roll diameter and initial crown as the roll chance 1 and when the present invention is applied.
(Product thickness), the thermal crown predicted at the time of rolling, and the amount of deviation between the corrected plate crown and the target plate crown when the pass schedule is set. In this roll chance 2, since the thin material is large and the thermal crown is small, it is inappropriate to use the same initial crown as the roll chance 1, and the plate crown is larger than the target in most materials. I have.

On the other hand, when the present invention is applied, the initial crown is 0.6 mm, and since the pass setting that satisfies the target plate crown is made for most of the rolled materials, the effectiveness of the present invention is sufficiently recognized. . In addition, the present invention
It is not limited to the above embodiment.

[0030]

According to the present invention, it is possible to set a pass satisfying the target plate crown.

[Brief description of the drawings]

FIG. 1 is a graph showing a correspondence between a predicted value and a measured value of a thermal crown.

FIG. 2 is a graph showing a correspondence relationship between an estimated value and an actually measured value with respect to a wear profile of a work roll.

FIG. 3 is a graph of a pass schedule setting based on a sheet crown prediction.

FIG. 4 is a graph showing a roll size, a thermal crown, and a shift of a corrected plate crown with respect to a target plate crown at roll chance 1;

FIG. 5 is a graph showing a roll size, a thermal crown, and a deviation of a corrected plate crown from a target plate crown at roll chance 2;

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-80709 (JP, A) JP-A-9-141312 (JP, A) JP-A-7-265927 (JP, A) JP-A 8- 141621 (JP, A) JP-A-54-114461 (JP, A) JP-A-55-92215 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37 / 00-37 / 78 B21B 27/00-27/02

Claims (4)

(57) [Claims] 1. A target sheet thickness, reflecting a roll crown,
A method for determining an initial crown of a work roll by using a pass schedule setting method in which a plate crown is secured and a shape dead zone is taken into consideration. Based on the determined rolling order, the wear crown of the work roll at the time of each slab rolling, and the thermal crown are predicted, and a preset initial crown is added to these predicted values to obtain the roll crown of the work roll at the time of each slab rolling. Based on the obtained roll crown, it is determined whether or not the target plate crown can be secured by using the pass schedule setting method, so that the number of slabs satisfying the target plate crown is maximized.
A method for determining an initial crown of a work roll, wherein the initial crown is changed. 2. A pass schedule setting method which reflects the roll crown, secures a target sheet thickness and a sheet crown, and takes a shape dead zone region into consideration. The exit side crown is determined by a plate crown prediction model equation given by the following equation: _Ch = f (C _W , C _B , B, P, h, H,
C _H , R _W , R _B ) where C _W = C _I + C _T + C _{E Ch} : Delivery plate crown C _W : Roll crown of work roll C _B : Abrasion amount of backup roll B: Plate width P: Rolling load h: exit side thickness H: thickness at entrance side C _H: entrance side crown R _W: work roll radius R _B: the backup roll radius C _I: initial crown C _T: thermal crown C _E: abrasion crown and, in the final pass The output-side sheet crown ratio is calculated by dividing the target output-side sheet crown by the target output-side sheet thickness, and based on the calculated value, the entrance-side sheet crown ratio in the final pass is calculated using the prediction model formula. The method according to claim 1, wherein a change in the sheet crown ratio obtained as a difference in the sheet crown ratio is determined, and the rolling load and the exit side sheet thickness are determined so that the change in the sheet crown ratio is in the shape dead zone region. Item 3. The method for determining an initial crown of a work roll according to Item 1. 3. The target thickness, reflecting the roll crown,
A method for determining an initial crown of a work roll by using a pass schedule setting method in which a plate crown is secured and a shape dead zone is taken into consideration. Based on the determined rolling order, the thermal crown of the work roll at the time of each slab rolling is predicted, and a preset initial crown is added to the predicted value to obtain the roll crown of the work roll at the time of each slab rolling. Under the roll crown, it is determined whether or not the target plate crown can be secured using the pass schedule setting method, so that the number of slabs satisfying the target plate crown is maximized.
A method for determining an initial crown of a work roll, wherein the initial crown is changed. 4. A method for grinding a work roll, wherein the roll is ground during rolling so as to secure the initial crown determined by the method according to claim 3.