JPS6121722B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a strip width rolling method, and in particular, a strip width rolling method suitable for performing multiple reversible rollings in a strip width rolling mill disposed in the front row of a coarse mill group of a hot strip mill. Regarding the method. Generally, in a rough mill group of hot strip mills, after the slab as a rolled material is rolled to a large width reduction by the width rolling mill located in the front row, it is rolled to the subsequent thickness rolling mill. Therefore, it is possible to perform plate thickness rolling to obtain a predetermined plate width and thickness. Here, the plate width at the leading end of the slab, which has been subjected to large width reduction rolling in the above-mentioned plate width rolling mill, is narrower than the plate width in the steady deformation region by the amount of width drop.
Note that no width drop occurs at the rear end of the slab. The above-mentioned width drop at the tip of the slab later causes insufficient width of the slab, and is one of the main causes of reduction in rolling yield. The present invention makes it possible to obtain the best strip width shape through strip width rolling by optimizing the setting of the width reduction amount in strip width rolling and minimizing the amount of width reduction that occurs at the ends of the rolled material. The purpose of the present invention is to provide a width rolling method. In order to achieve the above object, the present invention provides a sheet width rolling method in which a rolled material is reversibly rolled multiple times using vertical rolls to achieve a target full width reduction amount. Therefore, the set width reduction amount of the vertical rolls in each of all passes is adjusted so that the amount of width reduction that occurs at the tip of the rolled material matches the set width reduction amount of the vertical rolls in each subsequent pass following each preceding pass. It is designed to define. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a state in which a slab 11 as a rolled material is rolled by a width reduction amount ΔW by a rolling roll (vertical roll) 12 of a width rolling mill. At the tip of the slab 11, a width drop δ occurs. According to the results of experiments conducted by the present inventor, there is a relationship between the width reduction amount △W and the width reduction amount δ as follows: δ=(△W)...(1) When the initial plate thickness is 200 mm and the initial plate width 1000
For example, if we perform a theoretical analysis using the rigid-plastic finite element method when a mm slab is width-rolled using rolling rolls with a diameter of 1000 mm, a curved relationship of δ≒a√△ will be established as shown in Figure 2. It is permitted to do so. Note that the relationship between the width reduction amount △W and the width reduction amount δ is the same for normal slabs (initial thickness 150 mm or less).
300 mm, initial plate width 800 mm to 1.500 mm) is rolled under normal rolling conditions, the curve relationship roughly shows the curve shown in Figure 2, although there are some variations depending on the initial shape of the slab. Next, when the rolled material is reversibly rolled three times to achieve the target full width reduction amount △Wt, the amount of width reduction that occurs at the tip of the rolled material due to the rolling of the preceding pass, If we analyze how the amount of width reduction that occurs at the tip of the rolled material due to rolling in subsequent passes changes in relation to the set width reduction amount of the rolling rolls 12 in subsequent passes, we will find the following: becomes. That is, when rolling is performed by the set width reduction amount ΔW ₁ of the rolling roll 12 in the first pass, it is assumed that a width reduction amount δ ₁ occurs at the tip of the rolled material. Note that no width drop occurs at the rear end of the rolled material. Next, the rear end of the rolled material rolled in the first pass is used as the tip in the second pass, and in the second pass rolling is performed by the set width reduction amount ΔW ₂ of the rolling rolls 12. The shape of the leading and trailing ends of the rolled material after rolling by the second pass results in the following (1) and (2) depending on the magnitude relationship between ΔW ₂ and δ ₁ . (1) When △W ₂ <δ ₁ , the result is as shown in Figure 3A. That is, a width drop occurs at the tip by a width drop amount _δ2 . On the other hand, the plate width at the rear end is the width reduction amount △
Since it is smaller than the distance between the rolling rolls that perform rolling at W ₂ , a part of the rear end is not rolled at all,
At the rear end, an insufficient board width of δ ₁ −ΔW ₂ occurs, which is obtained by subtracting the set width reduction amount ΔW ₂ of the rolling rolls 12 in the second pass from the width reduction amount δ ₁ in the first pass. That is, when W ₂ <δ ₁ , a region with insufficient board width occurs not only at the leading end of the rolled material but also at the trailing end. Here, the length in the rolling direction that causes the strip width shortage, that is, the strip width shortage length l ₂ is the sum of the strip width shortage length l ₂₁ on the leading edge side and the strip width shortage length l ₂₂ on the rear end side, That is, it is expressed as l ₂ = l ₂₁ + l ₂₂ (2). Here, in the range of the set width reduction amount ΔW of the rolling roll 12 that is normally adopted, it can be considered that even if the width reduction amount ΔW is large, the width reduction amount δ is saturated to a substantially constant value. can. Therefore, even if the set width reduction amount ΔW ₂ of the rolling roll 12 in the second pass increases, as δ approaches ₁ , l ₂₁ in the above formula (2) becomes approximately constant and l ₂₂ decreases. Therefore, the plate width shortage length l ₂ becomes smaller as the set width reduction amount ΔW ₂ of the rolling roll 12 in the second pass approaches the width drop amount δ ₁ in the first pass. (2) When △W ₂ > δ ₁ , the result is as shown in Figure 3B. That is, a width drop occurs at the tip by a width drop amount _δ2 . On the other hand, since the entire region of the rear end is rolled, there is no longer a shortage of board width. In other words, the insufficient length of the plate width in this case
l ₂ is determined only by the short plate width length l ₂₁ on the tip side. As shown in FIG. 2, the width reduction amount δ ₂ due to the second pass is
2 becomes larger as the set width reduction amount △W ₂ becomes larger. Therefore, the width reduction amount δ ₂ in the second pass becomes smaller as the width reduction amount ΔW ₂ approaches the width reduction amount δ ₁ due to the first pass. According to (1) and (2) above, in order to minimize the short plate width length l ₂ and width drop amount δ ₂ after the second pass rolling, △W ₂ = δ ₁ …(3) It is necessary to set the set width reduction amount ΔW ₂ of the rolling roll 12 in the second pass so that the following relationship holds true. Similarly, in order to minimize the short plate width length l ₃ and width drop amount δ ₃ after the third pass rolling, the following relationship should be established: △W ₃ = δ ₂ (4) It is necessary to set the width reduction amount _δ3 in the third pass. That is, the slab 11 rolled in the first pass as shown in FIG. 4A is rolled in the second pass by ΔW ₂ =
By rolling under the condition of δ ₁ , it is possible to obtain a sheet width shape as shown in FIG. 4B. Further, the slab 11 rolled in the second pass as shown in FIG _.
If rolling is carried out under conditions that satisfy the relationship _δ2 , it is possible to obtain a sheet width shape as shown in FIG. 4C. FIG. 5 shows the respective set width reduction amounts △W ₁ , △ of the rolling roll 12 in the three passes shown in FIG. 4 A to C above.
FIG. ₂ is a diagram showing the relationship between W 2 and ΔW ₃ and width drop amounts δ ₁ , δ ₂ , and δ _3. FIG. In this Figure 5, the curve
C ₁ is _the same as _the curve _shown in FIG.
It is translated by W ₁ and △W ₂ . According to this FIG. 5, the width reduction amounts δ ₁ , δ ₂ , δ ₃ in each pass are obtained by the rolling shown in FIGS.
It is recognized that as the rolling progresses, the value gradually decreases. Next, in implementing the present invention, it is assumed that the relationship between the width reduction amount δ and the width reduction amount ΔW is known as shown in equation (1) above, and
A setting procedure for optimizing the set width reduction amount △W ₁ , △W ₂ , △W ₃ of the rolling roll 12 in each pass when the full width reduction amount △Wt by all passes is determined in advance will be explained. . First, above (1)
From equations and equations (3), δ ₁ =(△W ₁ )=△W ₂ (5) holds true. Further, from the above equations (1), (4), and (5), the following holds true: δ ₂ =(ΔW ₂ )=((ΔW ₁ ))=ΔW ₃ (6). On the other hand, between the full width reduction amount △Wt and each width reduction amount △W ₁ , △W ₂ and △W ₃ , △Wt=△W ₁ +△W ₂ +△W ₃ …(7) holds true. . Therefore, the above equations (5), (6) and
According to equation (7), △Wt=△W ₁ +(△W ₁ ) +((△W ₁ ))...(8) holds true. Therefore, △W ₁ is calculated from the above equation (8), and △W ₂ and △W ₃ are calculated using the above equations (5) and (6), respectively. Next, specific examples of the present invention will be described. FIG. 6 is a control system diagram used in implementing the present invention, and FIGS. 7 and 8 are drive system diagrams of a strip width rolling mill used in implementing the present invention. Information regarding rolling, such as the composition of the rolled material, temperature, slab width, and finished product width, is input to the control device 22 from the outside. The calculator 21 calculates the plastic constant M of the rolled material based on the information on the components and temperature.
The calculator 22 calculates the full width reduction amount ΔWt in the strip width rolling mill based on the information on the slab width and finished product width. Equations (5), (6), and (8) are set in advance in the arithmetic unit 23, and therefore the arithmetic unit 23 calculates the full width reduction amount △ calculated by the arithmetic unit 22.
Based on Wt, the set width reduction amounts ΔW ₁ , ΔW ₂ , and ΔW ₃ of the rolling roll 12 in each pass are calculated. The calculator 24 calculates the plasticity constant M calculated by the calculator 21 and the respective width reduction amounts △W ₁ , △ calculated by the calculator 23.
Rolling load in each pass based on W ₂ and △W ₃
Calculate P ₁ , P ₂ , and P ₃ . The calculator 25 calculates the mill constant K, the initial slab width W ₀ , the steady-state slab width W ₀₁ after the first pass, the steady-state slab width W ₀₂ after the second pass, and the width in each pass calculated by the calculator 23 . Reduction amount △
Based on W and the rolling load P in each pass calculated by the calculator 24, the roll opening degrees S ₁ , S ₂ , and S ₃ in each pass are calculated by the following equations (9) to (11). S ₁ =W ₀ −△W ₁ −P ₁ /K …(9) S ₂ =W ₀₁ −△W ₂ −P ₂ /K …(10) S ₃ =W ₀₂ −△W ₃ −P ₃ /K ...(11) The roll opening degrees S ₁ , S ₂ , S ₃ in each pass calculated by the calculator 25 are transmitted to the setting device 26 .
The setting device 26 gives a rotation command to the electric motor 27 based on the roll opening degrees S ₁ , S ₂ , S ₃ and also controls the actual roll opening based on a feedback signal from a pulse transmitter 28 connected to the electric motor 27. While recognizing the rotation angle, a rotation command is issued until the roll opening angle of the strip width rolling mill reaches S ₁ , S ₂ or S ₃ . electric motor 27
The rotation of the worm shaft 29 and the worm wheel 3
0, and the opening degree of the rolling roll 12 supported by the housing 31 is set to the predetermined opening degree. Next, concrete implementation results by the present inventor will be explained. Table 1 shows the results of conventional rolling in which reversible three-pass rolling was performed in a strip width rolling mill, and the rolling results of the present invention. In addition, in these rolling processes, the initial thickness of the slab is 200mm, and the initial width is 1000mm.
mm, and the rolling roll diameter was 1100 mm.

[Table] According to Table 1 above, it is recognized that by implementing the present invention, the amount of width drop that occurs at the end of the rolled material is minimized. As described above, the present invention reversibly performs plate width rolling on a rolled material multiple times using vertical rolls,
In a strip width rolling method that rolls a target full width reduction amount, the amount of width reduction that occurs at the tip of the rolled material due to rolling in each preceding pass, and the set width of the vertical roll in each subsequent pass following each preceding pass. Since the set width reduction amount of the vertical rolls in each of all passes is determined so that the width reduction amount matches the width reduction amount, the setting of the width reduction amount in plate width rolling can be optimized and the width drop that occurs at the edge of the rolled material can be reduced. This has the effect that the amount can be minimized, and the best width shape of the sheet can be obtained through sheet width rolling.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the state of strip width rolling, Fig. 2 is a diagram showing the relationship between width reduction amount and width reduction amount, Fig. 3 A
FIG. 3B is a plan view showing the rolling state under different rolling conditions in the second pass, FIG.
Figures B and 4C are plan views showing the rolling state according to the present invention, Figure 5 is a diagram showing the relationship between the width reduction amount and the width drop amount during rolling according to the present invention, and Figure 6 is a diagram showing the relationship between the width reduction amount and the width drop amount during rolling according to the present invention. 7 and 8 are drive system diagrams used to implement the present invention. 11... Slab, 12... Roll, △W,
△W ₁ , △W ₂ , △W ₃ ... Width reduction amount, △Wt ... Full width reduction amount, δ, δ ₁ , δ ₂ , δ ₃ ... Width reduction amount.

Claims (1)

[Claims] 1. In a sheet width rolling method in which a rolled material is reversibly rolled multiple times using vertical rolls to achieve a target full width reduction amount, a Width drop amount and
A sheet width rolling method characterized in that the set width reduction amount of the vertical rolls in each of all passes is determined so that the set width reduction amount of the vertical rolls in each subsequent pass following each preceding pass is the same.