JPH0698370B2 - Board width control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a strip width control method in hot rolling.

[Prior Art] The hot rolling process of a steel sheet is roughly divided into two processes, rough rolling and finish rolling. Vertical rolling machines and horizontal rolling are alternately performed in the rough rolling process, and a tandem mill is used in the finish rolling process. Horizontal rolling is performed. A slab manufactured by continuous casting or agglomeration is heated in a heating furnace, or it is received as a hot piece and hot-rolled by a rough rolling machine and a finishing rolling machine to obtain a product having a required plate width and plate thickness. Manufacturing.

In the above-mentioned rolling process, the roll gap of the vertical rolling mill was controlled as follows. That is, the margin that takes into account the strip width fluctuation of the rolling material in the finish rolling mill is added to the target finishing strip width, and the value corrected based on the setup control described later becomes the target strip width of the finishing rolling mill. The roll gap was adjusted. The setup control was to correct the target strip width on the entry side of the finish rolling mill based on the amount of mill spring generated by the rolling reaction force of the vertical rolls of the vertical rolling mill and the width expansion of the rolled material during horizontal rolling.

[Problems to be solved by the invention]

In the rolling process described above, the extra width added to the target strip width was merely determined based on an empirical rule, and the extra width was set with a sufficient margin to prevent defective products. Therefore, this extra width has been a cause of a decrease in yield.

[Means for solving problems]

As a result of various studies and analyzes, the inventor of the present application has a strip width expansion amount and a strip width contraction amount in the strip width variation amount in the finish rolling mill, and further, the strip width expansion amount and the strip width contraction amount are respectively calculated as It was found that it can be calculated based on the strip width, strip thickness, tension between stands, material temperature, and deformation resistance. By using this calculated value for setup control, the margin can be reduced and the yield can be increased.

The present invention has been made on the basis of such knowledge, and an object thereof is to calculate a plate width expansion amount and a plate width contraction amount in a finish rolling machine in hot rolling, and to calculate the calculated value. Another object of the present invention is to propose a plate width control method that can reduce the excess width and improve the yield by using the setup control.

A strip width control method according to the present invention has a plurality of stands, in a strip width control method in a hot rolling facility equipped with a finish rolling mill for horizontally rolling a strip to a vertical strip mill, the strip width of the strip, Based on the plate thickness, the tension between stands, the material temperature, and the deformation resistance, the plate width expansion amount and the plate width contraction amount in the finish rolling mill are calculated, and based on the calculated value and the target plate width on the exit side of the finish rolling mill. The target strip width on the entry side of the finish rolling mill is obtained, and the roll gap of the vertical rolling mill is controlled based on the target strip width.

〔Example〕

The present invention will be described below with reference to the drawings showing an embodiment thereof. FIG. 1 is a schematic configuration diagram of an apparatus for carrying out the present invention, in which 1 represents a rolled material being conveyed as indicated by an arrow (rightward in the figure).

A vertical rolling mill 2 and a horizontal rolling mill 3 that perform rough rolling in order from the upstream side of the rolling material 1 in the rolling direction, and rolls 4a, 4b of 6 stands,
A finishing rolling mill 4 equipped with 4c, 4d, 4e and 4f is installed. Then, as the rolled material 1 is conveyed, the vertical rolling mill 2
Then, the product is roughly rolled by the horizontal rolling mill 3 and then finish-rolled by the finish rolling mill 4 to obtain a finished product.

In addition, a rolling entry side strip width measuring device 5 is provided on the upstream side of the vertical rolling mill 2.
Further, a rolling exit side strip width measuring device 6 is provided on the downstream side of the finish rolling mill 4, and the strip widths WA ₁ , WA ₂ of the rolled material are provided at the respective portions.
Is designed to measure. These measured board widths
WA ₁ and WA ₂ are used to obtain the plate width feedback amount ΔWFB in order to perform feedback calculation on the target plate width W by the following equation (1).

ΔWFB = WA ₂ −WA ₁ (1) The plate width feedback amount ΔWFB calculated as described above is input to the adder 8 where it is added to the target plate width W calculated based on the method described later.

In addition, a width expansion calculation device 9 that calculates the plate width expansion amount in the finish rolling mill 4 based on the calculation formula described later, and a width shrinkage calculation device that calculates the plate width contraction amount in the finish rolling mill 4 based on the calculation formula described later. 10 and a widening calculation device 9
Width spread amount ΔW _E calculated by
The plate width contraction amount ΔW _S calculated in step 1 and the adder 8 output are input to the adder 11, and the adder 8 outputs the plate width expansion amount ΔW _E and the plate width contraction amount in the adder 11. It is designed to be corrected by ΔW _S. The adder 11 obtains the spreader entry side aim plate width WF _O finish at these correction values, and the calculated output W
F _O is input to the vertical roll gap controller 12. The vertical roll gap control device 12 has a target strip width WF on the entry side of the finishing mill.
Vertical rolling mill 2 obtained in advance from _O and reduction schedule 2
The gap amount of the vertical rolls of the vertical rolling mill 2 is determined based on the reduction amount of the vertical rolling mill 2, and the vertical roll gap control signal is supplied to the gap control motor of the vertical rolling mill 2.

Next, a method of calculating the width expansion amount ΔW _E and the width contraction amount ΔW _{S in} the finish rolling mill 4 will be described. Fig. 2 shows an example of the actual amount of strip width spread in the finish rolling mill 4 as it passes through the six rolls of the finish rolling mill 4 (rolled material: finished strip thickness 2.0 mm, strip width 91
4 mm), where the horizontal axis is 6 of finish rolling mill 4
The base roll symbol and the vertical axis indicate the cumulative value (unit: mm) of the strip width expansion amount in the finish rolling mill 4. The strip width spread value [Delta] W _E of the finishing mill 4 of the strip of this rolling timetable in width spread calculation unit 9, is calculated in advance based on the following equation (2).

ΔW _E = f (Hi, Ho, R, Wi) (2) where Hi: Inlet plate thickness Ho: Outlet plate thickness R: Roll radius Wi: Inlet width On the other hand, Fig. 3 shows tension between stands and plate width shrinkage ratio Is a graph showing the relationship with, where the horizontal axis is tension between stands α (unit: kg / m
m ² ), the vertical axis shows the strip width shrinkage ratio β (unit%) in the finish rolling mill, and (A), (B) and (C) in the figure show the rolling temperatures of 1000 ° C, 950 ° C and 900 ° C, respectively. Shows the case. Therefore, as shown in FIG. 3, the plate width shrinkage ratio β is a linear function of the inter-stand tension α, and the following relational expression (3) is established between α and β.

β = cα + d (3) (where c, d are constants determined by material temperature, deformation resistance, plate width, plate thickness) Therefore, the plate width shrinkage amount ΔW _S is calculated by the following formula (4) ).

ΔW _S = W · β = W (cα + d) (4) The width shrinkage amount ΔW _S in the finish rolling mill 4 of the rolling material to be rolled this time is calculated in advance by the width shrinkage calculation device 10 based on the equation (4). Keep it.

Next, the plate width control method according to the present invention will be described. First, the target strip width W on the delivery side of the finish rolling mill is determined by the following equation (5).

W = (W _O + a) (1 + b) (5) where W _O : plate width in low temperature state a: extra width b: hot correction coefficient according to finishing temperature Next, the plate obtained by the formula (1) Width feedback amount ΔWF
B is added by the adder 8 to the target plate width W calculated in advance based on the equation (5). Further, in the adder 11, the adder 8
The width expansion amount ΔW _E in the finish rolling mill 4 calculated in advance by the above-described calculation method is subtracted from the output from the above, while the width shrinkage amount ΔW _S is added, and the correction value, that is, the entry side of the finish rolling mill 4 the aim plate width WF _O is transmitted to the vertical roll gap control device 12.

In the vertical roll gap controller 12 at the end, the vertical roll gap amount by a reduction ratio of the vertical rolling mill 2, which is predetermined by aiming plate width WF _O and rolling schedule of the finishing rolling mill entry side input from the adder 11 is The vertical roll gap signal is transmitted from the vertical roll gap control device 12 to the gap control motor (not shown), and the roll opening / closing of the vertical rolling mill 2 is controlled.

The above-mentioned control based on the predetermined amount of reduction of the vertical rolling mill 2 is performed as follows, for example, and this strip width control method is a method proposed by the applicant of the present application (Japanese Patent Laid-Open Publication No. Sho.
59-147706), and the summary is as follows.

In a rough rolling mill group in which vertical rolling mills and horizontal rolling mills are alternately arranged, a vertical rolling mill that performs final vertical rolling of the rough rolling mill group and a vertical rolling mill upstream of one of the vertical rolling mills are A plate width control function capable of controlling the roll opening during rolling of the rolled material is added to each of the plate width control stands, and a predetermined value is given to each of the plate width control stands as an average width killing amount in the longitudinal direction of the rolled material. Then, so that the average width of the rough rolling mill group side becomes the target width, the material to be rolled is rolled according to the rolling schedule determined by obtaining the width killing amount of the vertical rolling mill other than the strip width control stand, The strip width control stand controls the roll opening during rolling of the material to be rolled.

In this embodiment, the control method of the vertical rolling mill located on the upstream side of the finishing rolling mill is described, but the present invention can be applied to the edge width between stands in the finishing rolling mill or the strip width control by the looper tension.

〔effect〕

As described in detail above, according to the present invention, the roll gap of the vertical rolling mill is controlled based on the value obtained by correcting the target strip width W in consideration of the strip width expansion ΔW _E and the strip width shrinkage amount ΔW _S in the finish rolling mill. As a result, the strip width after finish rolling can be accurately controlled with respect to the target strip width W. As a result, the margin previously added in consideration of the amount of change in the finish rolling mill can be significantly reduced, and the yield can be improved. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for carrying out the present invention, FIG. 2 is a graph showing a plate width expansion amount, and FIG. 3 is a graph showing a relationship between a plate width shrinkage ratio and tension between stands. 1 ... Rolled material, 2 ... Vertical rolling mill, 3 ... Horizontal rolling mill,
4 ... Finishing rolling mill, 5 ... Incoming strip width measuring instrument, 6 ... Outgoing strip width measuring instrument, 7 ... Feedback amount calculation device, 8, 11 ...
... Adder, 9 ... width expansion calculation device, 10 ... width reduction calculation device, 12 ... vertical roll gap control device

Claims (1)

[Claims] 1. A strip width control method in a hot rolling facility having a finish rolling mill having a plurality of stands for horizontally rolling rolled strips downstream of a vertical rolling mill, comprising the strip width, strip thickness, and stand of rolled strips. The strip width expansion amount and strip width shrinkage amount in the finishing rolling mill are calculated based on the inter-tension, the material temperature, and the deformation resistance, and based on this calculated value and the target strip width on the exit side of the finishing rolling mill, the finishing rolling mill entry is performed. 2. A strip width control method, characterized in that a target strip width on the side is obtained, and the roll gap of the vertical rolling mill is controlled based on the target strip width.