JPS6012136B2 - Roll opening setting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention proposes a method for setting the roll opening of a vertical rolling mill, which makes it possible to accurately achieve a target strip width in hot assembly rolling.

The roughing mill group that hot-rolls slabs consists of multiple vertical rolling mills and horizontal rolling mills arranged alternately, and the vertical rolling mill obtains the target strip width on the output side of the roughing mill group. In order to achieve this, they are used to cut the required width.

Conventionally, the roll opening of the vertical rolling mill to perform this width reduction has been determined based on rolling conditions such as slab width, slab thickness, target strip width at the exit side of the rough rolling mill, horizontal rolling pass schedule, and rolling temperature, as well as rolling mill conditions. This is done economically by taking into account constraints such as power, bite angle, twist and inclination in the width direction of the rolled material during vertical rolling, and the actual amount of width loss is not accurately grasped. That was the reality. Therefore, the accuracy of the average strip width (average value in the longitudinal direction of the rolled material strip width) on the rough rolling mill/group exit side is low, and for this reason, the exit side strip width is set wider than the originally required target strip width. This was the key to improving the yield of hot strip products. Now, when vertical rolling is not performed at all during rough rolling, the width at the leading and trailing ends of the rolled material becomes wider compared to the middle part, whereas when vertical rolling is performed, The phenomenon that the plate width at the end portions becomes narrower is well known.

By the way, in the latter case, in a certain strip width dimension range, when the width reduction amount is increased in the upstream stand of the rough rolling mill group and the width reduction amount is decreased in the downstream stand, the width reduction amount is increased at the leading and trailing ends of the material to be rolled. The width narrowing amount (difference in board width between the middle part, which is wider than the tip and rear ends) becomes larger, and conversely, the upstream stand also reduces the trowel width reduction,
The inventors' research has revealed that when the width reduction amount is increased in the downstream stand, the width narrowing amount described above becomes smaller. Therefore, by devising the distribution of the width reduction amount by each vertical rolling mill, it is possible to reduce the narrowness at the leading and trailing ends of the rolled material, and also to reduce the shape of the fishtail (fishtail-shaped irregularly shaped part) at the leading and trailing ends. It should be possible to reduce the amount of cropping at the leading and trailing edges by changing the . In other words, there should be an optimal width reduction amount distribution depending on slab dimensions, rolling conditions, etc., but when determining the roll function of a vertical rolling mill empirically as in the past,
There is a problem in that the accuracy of the average board width deteriorates as the distribution of the width reduction amount is changed, and in reality, it is impossible to change the distribution of the width reduction amount. The present invention has been made in view of the above circumstances, and it is possible to obtain the target strip width with high accuracy on the roughing mill group exit side even when the width reduction amount distribution of each vertical rolling mill is arbitrarily set. The purpose is to provide a sheet width control method that makes it possible to control the sheet width.

Therefore, in order to achieve the target strip width with high accuracy when the width reduction amount of each vertical rolling mill is arbitrarily set, it is necessary to combine the width reduction amount by vertical rolling and the width expansion amount by horizontal rolling. It is necessary to accurately quantify the relationship.

The present inventors have accurately expressed this relationship into formulas, created a mathematical model that accurately estimates the strip width of each vertical rolling mill and each horizontal rolling mill that constitutes the rough rolling mill group, and Achieved a highly accurate target board width on the exit side. The roll opening setting method according to the present invention provides a target strip width of a material to be rolled on the exit side of the roughing mill group when hot rolling is performed by a roughing mill group including a plurality of vertical rolling mills and a horizontal rolling mill. When setting the roll function in order to realize The distribution ratio of the width reduction amount should be made to match the distribution ratio of the width reduction amount arbitrarily given in advance. It is characterized by setting the roll opening degree.

Next, the basic principle of the present invention will be explained. First, the relationship between width reduction by a vertical rolling mill and width expansion by a horizontal rolling mill will be explained based on FIGS. 1a to 1c. Figure 1a is a cross-sectional view in the width direction and perpendicular to the rolled material before vertical rolling, Figure 1b is the same cross-sectional view after vertical rolling (before horizontal rolling), and Figure 1c is after horizontal rolling. It is the same sectional view. Rolled material la before vertical rolling,
Rolled material lb after vertical rolling and rolled material l after horizontal rolling
c The plate width and plate thickness are respectively W, DD, WE, HE, and W.
, h, the width reduction amount △W (△W/2 on one side) by the vertical rolling mill is expressed as △W = W - WE, and by performing the width reduction, only the width direction edges are raised. Become. The width of this raised portion SE appearing on the rolled material lb is expanded by the next horizontal rolling wM (wM/2 on one side), and the middle rectangular cross section excluding the raised portion SE is also expanded in width by the horizontal rolling. If the amount is wH (wH/2 on one side), then the sheet width W after horizontal rolling is expressed as w=VVE+wM+wH...{1}.

However, the width expansion amounts wM and wH can be approximated as follows (2}, using the condition that the volume is constant before and after vertical and horizontal rolling.
It is expressed as in the formula {3}. wMniCME・△W
…■WH three {(bitter)…-・}WE……[3
1 However, CM ear: bulge width expansion coefficient CH: Width expansion coefficient by generally used horizontal rolling only However, the inventors conducted an actual machine test in which rough rolling mills can also be rolled, and as a result, the following {4} , CM in {5} formula
It was found that E, CM is expressed.

cME=〇. 22 (units).

・18・(Vessel).・19...{4'CH=2-
o&Xp{-・. 766 (general).・．． (harm). Scream. groove.
・However, ld: Projected contact length during horizontal rolling R: Roll radius of the horizontal rolling mill The present invention has developed a roll relationship setting calculation model for a vertical rolling mill by filling in the above formulas m to ■. .

Next, we will calculate the calculation method for this roll opening setting (setup) for each of the six vertical rolling mills E, ~E, as shown in the side view of Figure 3.
The case of a rough rolling mill in which horizontal rolling mills R and R6 are alternately arranged will be explained using the flowchart of FIG.

First, the width and thickness of the slab sent to the first rolling mill, that is, vertical rolling mill E, and the last rolling mill, that is, horizontal rolling mill Isono 6.
The rolling conditions such as the target width, target thickness, and rolling temperature of the rolling mill 1 on the exit side are input using an appropriate input device 11, and the distribution ratio of the width reduction amount of each vertical rolling mill is determined using the setting panel 12. , respectively, are input into the combination display 13 (■).

Based on this input information, the computer 13 performs horizontal rolling,
The pass schedule for vertical rolling is calculated, but in terms of vertical rolling, first, each vertical rolling mill E is , ~Determine the maximum width killing amount △ WE order x i (i = 1 to 6) for each of E6 (■)
. Next, the slab width Ws and the rough rolling mill outlet side, that is, the horizontal rolling mill R
6 Find the difference △Ws6 from the target width w ridge on the exit side, and calculate this △Ws
From 6 to 6, the width reduction amount ΔWE of the first vertical rolling mill E is predicted and calculated based on equation [6] (■).

△VVE,=A+B・△Ws6...{61 However, A, B
is a constant obtained from past performance data, and is updated and calculated each time performance data is obtained by computer 3, or calculated separately and calculated by computer 1.
As an example, A = 5 enemies, B = 0.
It is 7.

Next, the width reduction amount of the second to sixth vertical rolling mills E2 to E6 is determined (■). 2nd to 6th vertical rolling mill E2
~E6 width reduction amount △WEi (i=2-6) is {6}
Based on △W8, obtained by the formula, each vertical rolling mill E2~
It is determined by the following formula {7} using the width reduction amount distribution ratio Zj (i=2 to 6) of each E6. △WEi=Zi・
△VV8r”…{7} △WE obtained in this way
It is checked whether i (including i=1) is less than the previously calculated △W8max i (■), and for those exceeding WEmax i (NO), △WEm guy i → △W8
; Replace with (@).

Based on the width reduction amount ΔWEi (i=1 to 6) of each vertical rolling mill E, ~E6 determined in this way and the above-mentioned rolling conditions, the strip width w6 on the rough rolling mill group exit side and the width of each vertical rolling mill , ~ E6's roll function SBi (i=1 to 6) is calculated (■). The calculation of w6 and S8i is performed by assuming that the i-th vertical rolling mill i and the i-th horizontal rolling mill Ri downstream thereof are set as E,
m~(5'
Calculated by applying the formula. i.e. '11
Substituting the relationship [2}, '3-formula and △W=W-WE into the formula (1} formula becomes W=WE1C ship-△W+{〈Chapter)...-
．． }WE; C thin・△W+(chapter)...-(W-△W)=△W
{CME-(art) CH}+(pain)CHW------(
・')

Looking at this formula (1') and formulas ■ and ■ for the roughness of the i-th vertical rolling mill 5 j and horizontal rolling mill Ri, △W is △W
As Ei, and W as the upstream i-1th narrow exit plate width Wi-, (as the slab width in the first set), and h' as the horizontal pass schedule calculated separately. It is given from the calculation result. Next, the CM of formula (4)
W, △W, and day for E are the same as described above, and R in CH of the '5} formula is set in advance by the computer 13.
is given as a constant, and ld'ma day, h,
It is uniquely determined by R.

Regarding W8, W and △W are determined as described above.
It can be calculated as the difference from 8i. If you use these values to find the width of the exit side plate for each set one after another, you will get a good result. Note that SEi is determined from the difference between W (inlet plate width) and the width reduction amount ΔWEi in the i-th set, the calculated rolling load, and the mill rigidity. Once the strip width on the outlet side of the rough rolling mill group is determined in this way, the difference △w6A between this and the target strip width w6^ is determined by the following formula (■). △W Me ni W6^1 W6
...[8} And whether the absolute value of △w is less than or equal to the allowable tolerance 6 (for example, 0.5 ribs) of the width of the plate on the outlet side of the rough rolling mill group, that is, l△w6
＾lmi6... Check whether the condition of (9} is satisfied or not (■).

If this condition is satisfied (YES), the calculation of the roll relationship setting is completed, but if it is not satisfied (NO), the influence coefficient K of the width reduction amount on the strip width on the exit side of the roughing mill group (for example, K = -0.8), the first vertical rolling mill E,
The width killing amount △WE, is corrected as △W8・→AWE, 10K△w (■), and the process returns to step ■. And step ~
By repeating the process of ■, the condition of {9) is satisfied,
This calculation of role relationship settings is completed. The width reduction amount of each vertical rolling mill thus obtained is the above-mentioned substantial width reduction amount. Furthermore, ``According to the results of the actual calculations performed by the present inventors, the number of repetitions was less than four, and the calculation time was extremely short.'' In this way, the computer 3 calculates the opening. After completing the setting calculation, the calculation result is applied to each screw drive device 2 of each vertical rolling mill E, ~E6.
1 to 26, and thereby the roll relationship of each vertical rolling mill is set to the roll opening degree according to the calculation result.

On the other hand, the calculation results are displayed on the roll opening degree display panel 14 and are also printed and recorded by the printer 5. Next, the results obtained when the method of the present invention is implemented will be explained.

In the example, slab width Ws = 125 m, slab thickness Hs =
262 skin "Roughing mill group exit side plate width w6A = 1238 willow, width reduction amount distribution ratio (width reduction amount △W8 of the first vertical rolling mill E, is 1.0) is as shown in Table 1. Established as follows.
Table 1, FIG. 4 shows the setup calculation results for the first embodiment, and FIG. 5 shows the setup calculation results for the second embodiment in terms of the outlet strip width of each rolling mill.

The first embodiment is the first vertical rolling mill E. The second embodiment is a case where strong width cutting is performed in the second and third vertical rolling mills E2 and E3,
It can be seen from Figures 4 and 5 that the width reduction amount distribution ratio shown in Table 1 is realized. Note that the dots shown in FIGS. 4 and 5 are actually measured values of the plate width of the rolled material, which agree well with the calculated results in both Examples 1 and 2. Figures 6 and 7 are 1st and 2nd, respectively.
It is a graph showing the results of actually measuring the plate width w6 on the exit side of the rough rolling mill group from the tip to the rear end of the rolled material in the example,
It would be better to adopt the width reduction amount distribution ratio as in the second embodiment.

It can be seen that the narrow width at the rear end is improved. As detailed above, in the case of the method of the present invention, it is possible to improve the strip width accuracy on the exit side of the hot rough rolling mill group, and in some cases, it is possible to reduce the width narrowing at the leading and trailing ends of the rolled material. The present invention makes it possible to reduce the amount of hot
There is a real benefit in improving the yield of tap products.

[Brief explanation of drawings]

Figures 1 a to c are explanatory diagrams showing the relationship between width reduction in vertical rolling and width expansion in horizontal rolling, Figure 2 is a flowchart of calculations for setting the roll relationship according to the present invention, and Figure 3 is a rough A block diagram of the control system shown together with a side view of the rolling mill group, Figure 4; Figure 5 is a graph showing calculation results; Figure 6;
FIG. 7 is a graph showing the actual measurement results of the strip width of the total length of the rolled material at the exit side of the rough rolling mill. E, ~E6...Vertical rolling mill, R, ~R6...Horizontal rolling mill 11...Input device, 82... Width reduction amount distribution ratio setting board, 13... Computer,
14...Roll relationship display panel, 15...Printer, 21-26... ...Screw drive device. 6 figures, 7 figures, 1 figure, 3 figures, 2 figures, 4 figures, 5 figures

Claims (1)

[Claims] 1 When hot rolling is performed by a roughing mill group equipped with a plurality of vertical rolling mills and horizontal rolling mills, the roll opening degree is set in order to achieve the target strip width of the rolled material on the exit side of the roughing mill group. When carrying out, using the bulge width expansion coefficient due to vertical rolling and horizontal rolling and the width expansion coefficient due only to horizontal rolling,
The width reduction amount of each vertical rolling mill is calculated in order to make the distribution ratio of the actual width reduction amount of each vertical rolling mill that makes up the rough rolling mill group match the distribution ratio of the width reduction amount arbitrarily given in advance. A method for setting the roll opening of a vertical rolling mill.