JPH08267112A - Method for controlling planar shape of plate - Google Patents

Abstract

PURPOSE: To provide a method for controlling the planar shape of a plate at the time of rolling the plate by which the area of a crop is minimized and loss in the yield of products is reduced by making the planar shape of a steel plate after rolling into a rectangle. CONSTITUTION: At the time of rolling the plate by use of horizontal rolls 2 and vertical rolls 1, during broadside rolling with the horizontal rolls 2, before or after that, edging pass of parts corresponding to the tip and rear end part of the products is executed at a constant rolling reduction so that the sum of the crop area at the tip and rear end of the products and the crop area at both ends is minimized. Further, during finish rolling with the horizontal rolls 2, before or after that, edging pass of both side end parts of the products is executed with the vertical rolls 1 so that the rolling reduction in the vicinity of the tip and rear end parts of the products is smaller than the reference rolling reduction in the middle part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the plane shape of a thick plate, which can reduce the crop cut-off loss at the product rear end and both ends by making the plane shape of the rolled steel plate rectangular. .

[0002]

2. Description of the Related Art In plate rolling, a slab having a rectangular planar shape extracted from a heating furnace is first shaped and rolled for 2 to 4 passes in the longitudinal direction for the purpose of adjusting the thickness, and then this is rolled.
The product is rotated by 90 ° for tenter rolling to obtain a predetermined width, and then again rotated by 90 ° for finish rolling to obtain a predetermined length to obtain a product having a desired dimension.

FIG. 7 is a view showing a planar shape of a steel sheet after being rolled by a conventional horizontal roll. When thick plate rolling is performed only by rolling with horizontal rolls, the flat shape of the rolled steel plate depends on the width ratio (= rolling width / slab width). It becomes a drum shape with the width of the central part in the longitudinal direction of the steel plate widening, and the crop shape at the front and rear ends becomes a fishtail shape. Further, when the width-to-width ratio is small, the front and rear end portions are wider than the central portion as in (b), and the front and rear end crops are tongue-shaped.

Further, as a method of improving the planar shape defect caused by the above-mentioned rolling by the horizontal rolls, rolling in which horizontal rolls and vertical rolls are combined has been conventionally used.

FIG. 8 is a diagram showing a conventional method for improving the planar shape of a steel sheet by edging.

FIG. 1A is a diagram showing a method for improving the planar shape by edging with a vertical roll when rolling with a horizontal roll having a large width-width ratio, and during or before width-width rolling with a horizontal roll. By edging the fishtail-shaped portion at the front and rear ends (hereinafter referred to as "width-width edging"), the fishtail-shaped cropped portion (the hatched portion in the figure) is folded in the width direction to form a drum shape and a front-back shape. Improves the shape of the fishtailed end surface. On the other hand, (b) is a diagram showing a method of improving the planar shape by edging with a vertical roll when rolling with a horizontal roll having a small width-width ratio, and during or before finish rolling with a horizontal roll, Shaped both ends (hereinafter referred to as "finishing edging")
By doing so, the convex portion due to the width widening near the front and rear ends is folded into the front and rear ends, and the flat shape which is drum-shaped and tongue-shaped is improved. In actual rolling, the tentering edging and the finishing edging are combined to make the product into a rectangular plane shape.

For example, in Japanese Patent Publication No. 61-34886,
As shown in FIG. 9, the crop length ΔL and the width expansion amount ΔW represented by the following equations (1) and (2) are used as evaluation indices.
Width edging reduction ΔE _C and finishing edging reduction Δ so that they fall within the yield loss allowable range
A method for improving the plane shape by determining E _L and rolling has been proposed.

ΔL = ΔL _T + ΔL _B (1) ΔW = W _M − (W _T + W _B ) / 2 (2) where ΔL _T : Crop of the tip length △ L _B: crop length of the rear end portion W _M: width of the central portion W _T: the width of the end portion W _B: the width of the rear end portion, however, in the method in JP-B 61-34886, the plate width shape Since only the deviation ΔW of the width between the front and rear end portions and the central portion is captured, there are cases where the crop area at both ends of the product, which is the actual yield loss, cannot be accurately evaluated.

FIG. 10 is a diagram showing a planar shape of a rolled steel plate and product dimensions that can be taken from it. For example, when tentering rolling is performed using a horizontal roll, when a width reduction that minimizes the plate width occurs in a portion other than the central portion in the longitudinal direction as illustrated in FIG. 10B, there is no width reduction. Even if ΔW is the same as the shape of (a), the truncated crop area increases by the width decrease ΔWo. Therefore, when comparing the final product area after cropping,
As represented by the shaded area in the figure, the product area Sb in the case of (b) width reduction becomes smaller than the product area Sa in (a) without width reduction.

Further, Japanese Patent Publication No. 57-48286 discloses that the vertical roll opening is continuously changed in the longitudinal direction at the time of finishing edging, so that a flat shape such as a drum shape or a drum shape generated when the horizontal roll is pressed down is obtained. Is disclosed, and the crop area at both ends of the product is minimized is disclosed. However, the minimization of the crop area at the front and rear ends is not considered, and it is not optimal in the sense of reducing the yield loss.

Further, in Japanese Patent Laid-Open No. 5-185105, before and after or during the tentering rolling, edging is performed so that the leading and trailing end portions are lighter than the rolling amount at the central portion.
A method for optimizing the leading and trailing crop shapes is disclosed. However, this case is not a sufficient solution in terms of minimizing the crop area at both ends of the product.

[0012]

As described above, in the conventional plate rolling using horizontal rolls and vertical rolls, a technique for minimizing the amount of crops at both the leading and trailing end portions and the width end portion of the product is sufficient. It cannot be said that it is established. Therefore, an object of the present invention is to provide a platen plate shape control method at the time of plate rolling capable of reducing the yield loss of the product by making the planar shape of the rolled steel plate rectangular to minimize the crop area.

[0013]

The present invention has been made to solve the above problems, and is the sum of the front and rear end crop areas and the both end crop areas of the product (hereinafter, the crop area).
The optimum reduction pattern for the squeezing edging and the finishing edging is determined so as to minimize the width. In particular, in the finishing edging, the width reduction is reduced by using the light reduction at the front and rear ends.

That is, the gist of the present invention is that
"When rolling thick plates using horizontal rolls and vertical rolls,
To minimize the sum of the crop area at the front and rear ends of the product and the crop area at both ends, edging the part corresponding to the front and rear ends of the product with a vertical roll during or before and after tentering with horizontal rolls. In addition, during or before and after finishing rolling with horizontal rolls, thick plate flat shape control is performed by edging both ends of the product with vertical rolls so that the amount of reduction near the front and rear ends of the product becomes smaller than the reference amount of reduction at the center. Method ".

[0015]

According to the present invention, a simulation using a plane shape prediction model is used to search for a roll-down edging by a vertical roll and a reduction pattern at the time of finishing edging that minimizes the crop area of the product.

The plane shape prediction model will be described below.

FIG. 2 is a diagram showing an example of a change in plane shape of a steel sheet when edging and horizontal rolling are performed. By edging a steel plate having a substantially rectangular plane shape with a vertical roll, a bulge called a dog bone is generated at the end of the plate width. In order to flatten only this raised portion, the plane shape change when horizontal rolling with a horizontal roll is performed by approximating the crop shapes at both ends by an exponential function and the crop shapes at the front and rear ends by a quartic power function. It was found from the actual operation data that the equations (3) and (4) were used for rearranging.

Sv (x) = g1 (x, Win (x), Hv, S _E (x)) (3) Tv (y) = f1 (y, Wout, ΔWin, ΔWout) ... -(4) where Sv (x): crop shape of both width ends x: distance from the tip to the center in the longitudinal direction Win (x): plate width distribution before edging Hv: plate thickness before edging S _E ( x): Vertical roll opening Tv (y): Crop shape at the front and rear ends y: Distance from the plate center to the plate edge in the plate width direction Wout: Plate width after edging ΔWin: Width expansion amount before edging ΔWout: Amount of width expansion after edging Further, FIG. 3 is a diagram showing an example of a planar shape change of the steel sheet when only rolling with a horizontal roll is performed. Also in this case, if the crop shapes at both ends are approximated by an exponential function and the crop shapes at the front and rear ends are approximated by a quartic power function, the following equation (5) is obtained.
It was found from the actual operation data that it was arranged in (6).

Sh (x) = g2 (x, Hh, Δh) (5) Th (y) = f2 (y, Hh, Δh) (6) where Sh (x) : Crop shape at both ends x: Distance from the tip to the center in the longitudinal direction Hh: Plate thickness before horizontal rolling △ h: Reduction amount Th (y): Crop shape at the front and rear edges y: Distance from the plate center to the plate width direction It is possible to predict the planar shape of the product by calculating the planar shape changes shown in 2 and FIG. 3 based on the rolling schedule and superimposing them.

FIGS. 4 to 6 are views showing a method of determining a reduction pattern at the time of tentering edging and finishing edging by a vertical roll in order to minimize the cropped area of the steel sheet.

First, the following preconditions are defined.

As shown in FIG. 4, (a) the tenter edging by the vertical roll is a constant reduction amount ΔE in the width direction of the steel sheet.
_Let it be _C.

As shown in FIG. 4, in the finishing edging using the vertical roll of (b), the reduction amount (ΔE _L ) top at the front and rear ends in the longitudinal direction of the steel plate is set to the reference reduction amount at the central portion in order to prevent width reduction. The amount of reduction is smaller than ΔE _L , and the amount of reduction at that time is a front-back end symmetrical pattern at the position in the longitudinal direction of the steel plate.

The reduction pattern for the reduction amount is the light reduction start point P _S , the light reduction end point P _E , and (7) below.
It is determined by the front-to-rear end light rolling reduction r expressed by the formula.

R = (ΔE _L ) top / ΔE _L (7) In FIG. 4 (b), the light reduction start point P _S and the light reduction end point P _E are the same symbols at the front and rear end symmetrical positions. As shown, the light reduction start point P _S on the tip (biting end) side gradually increases the reduction amount after the end of the light reduction, and the predetermined reduction amount ΔE at the central portion.
_It means the time when it becomes _L, and the end point P _E of the light reduction on the rear end side is the predetermined light reduction amount (ΔE _L ) top as the reduction amount is decreased due to the light reduction. Means a point in time.

As shown in FIG. 5, (a) the amount of reduction ΔE _C during tentering edging by a vertical roll and (b) the amount of reduction ΔE _L during finishing edging are the physical limits of the equipment and the steel plate. Due to restrictions such as buckling and blistering scratches, the following (8),
An allowable range represented by the equation (9) is set.

0 ≦ ΔE _C ≦ (ΔE _C ) max (8) 0 ≦ ΔE _L ≦ (ΔE _L ) max (9) Here, in the present invention, a simulation based on a path schedule is performed. ΔE to minimize the crop area
Determine _C , ΔE _L , P _S , P _E , and r in the following order.

Step 1: As shown in FIG. 5, P _S , P
Fixed to _E with parameters ΔE _C , ΔE _L , r (0 ≦ r ≦ 1)
, Respectively, and the target values (ΔE _C ) opt, (ΔE _L ) opt, and ropt that minimize the crop area are determined. The broken line in the figure means that the amount of reduction was changed in order to determine the target value.

Step 2: Obtained in Step 1 (ΔE
_C ) opt, (ΔE _L ) opt, and ropt are fixed, and as shown in FIG. 6, the parameters P _S and P _E are swung within the range indicated by the broken line to minimize the crop area (P _S ) opt, ( P _E )
Determine opt.

It should be noted that in FIGS. 4 to 6 described above, the light reduction start point P
_S , the reduction amount between the light reduction end points P _{E is} linearly changed from the light reduction amount (ΔE _L ) top at the front and rear ends to the reference reduction amount ΔE _L at the central portion. Depending on the shape, the reduction amount may be changed stepwise between P _{S and} P _E , or P
_It is also possible to further divide _{S to} P _E and change the gradient that is the amount of change in the rolling reduction for each of the regions.

Further, in the present invention, the above calculation is actually performed online for each rolling slab based on the pass schedule, or the slab size, the tenter ratio, and the length ratio (= product length / slab length). It is also possible to select a reduction pattern at the time of edging in advance in a table divided according to, for example, and use the value of the table division that matches the condition at the time of actual rolling.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of the configuration of an apparatus for carrying out the method of the present invention.

The rolling schedule arithmetic unit 6 receives information such as slab size, slab temperature, and product size from the host computer, and determines a horizontal rolling pass schedule by horizontal rolls and an edging timing by vertical rolls. The horizontal rolling pass schedule and the edging timing are output to the cab monitor 8, and the operator performs horizontal rolling and edging based on the output schedule. A horizontal roll opening command based on the horizontal rolling pass schedule is transmitted to the horizontal rolling mill control device 7, and the horizontal rolling mill control device 7 controls the horizontal rolling mill 2 having horizontal rolls to perform rolling. On the other hand, the edger opening degree calculation device 5 which has received the horizontal rolling pass schedule and the edging timing from the rolling schedule calculation device 6 transmits the reduction pattern determined by the method of the present invention to the edger control device 4. The edger control device 4 sends a vertical roll opening command to the edger 1 having vertical rolls to perform edging based on the plate width of the central portion in the longitudinal direction of the steel plate measured by the plate width measuring device 3 and the transmitted reduction pattern.

Table 1 shows examples in which the conventional method and the method of the present invention are applied to thick plate rolling of various slab sizes and product sizes. In the conventional method, the amount of reduction of width-width edging and finishing edging is determined by using the width expansion amount ΔW and the crop length ΔL as evaluation indexes. Position) is constant. Here, the search for the amount of reduction and the reduction pattern was performed under the constraint conditions 0 mm ≦ ΔE _C ≦ 60 mm and 0 mm ≦ ΔE _L ≦ 60 mm.

[0035]

[Table 1]

From Table 1, by using the method of the present invention, the crop area is reduced to 42% on average as compared with the conventional method, and a great effect is achieved in reducing the cost of manufacturing thick steel plate.

[0037]

According to the method of the present invention, when performing plate rolling in a rolling facility having horizontal rolls and vertical rolls, it is possible to minimize the crop area which causes a yield loss,
It is very effective in reducing the manufacturing cost of thick plates.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus configuration for carrying out a method of the present invention.

FIG. 2 is a diagram showing an example of a planar shape change of a steel sheet when edging and horizontal rolling are performed.

FIG. 3 is a diagram showing an example of a planar shape change of a steel plate when only rolling with a horizontal roll is performed.

FIG. 4 is a diagram showing a method for determining a reduction pattern at the time of tentering edging and finishing edging by a vertical roll in order to minimize the cropped area of a steel plate.

FIG. 5 is a diagram showing a method of determining a reduction pattern at the time of tentering edging and finishing edging by a vertical roll in order to minimize the cropped area of a steel plate.

FIG. 6 is a diagram showing a method of determining a reduction pattern at the time of finishing edging by a vertical roll in order to minimize a crop area of a steel plate.

FIG. 7 is a diagram showing a planar shape of a steel sheet after being rolled by a conventional horizontal roll.

FIG. 8 is a diagram showing a conventional method for improving the planar shape of a steel sheet by edging.

FIG. 9 is a diagram showing a planar shape of a steel sheet after rolling for explaining the method disclosed in JP-B-61-34886.

FIG. 10 is a diagram showing a planar shape of a rolled steel plate and product dimensions that can be sampled therefrom.

[Explanation of symbols]

 1 Edger 2 Horizontal rolling mill 3 Strip width measuring device 4 Edger control device 5 Edger opening degree computing device 6 Rolling schedule computing device 7 Horizontal rolling mill control device 8 Driver's cab monitor

Claims (1)

[Claims] 1. When performing plate rolling using horizontal rolls and vertical rolls, during or before and after tenter rolling with horizontal rolls so that the sum of the crop areas at the front and rear ends of the product and the crop areas at both ends is minimized. In the above, the front and rear end equivalent parts of the product are edged by vertical rolls with a certain reduction amount, and during or before and after finish rolling by horizontal rolls, the reduction amount near the front and rear end parts of the product is smaller than the reference reduction amount in the central part. A method for controlling the planar shape of a thick plate, which comprises edging both ends of a product with a vertical roll so that