JPS6178503A - Rolling method of thick plate - Google Patents

Abstract

PURPOSE:To roll a slab into a thick finished plate with less plate-width deviation in the longitudinal direction, by preliminarily rolling the slab before its broadside rolling to make its thickness distribution uniform in the longitudinal direction by adjusting a rolling down position, before broadside rolling its end part in the longitudinal direction into a thick part. CONSTITUTION:In the preliminary rolling X of a slab SL before its broadside rolling; the slab SL is preliminarily rolled by changing and adjusting a rolling- down position in accordance with the changes of the deformation resistance and inlet thickness of the thick plate due to mainly a presence of skid mark, to obtain a pre-rolling finished material SB before broadside rolling, having the uniform thickness distribution in its longitudinal direction. Successively, the material SB is turned by 90 deg., and is subjected to rolling reduction in its longitudinal direction by a vertical mill in a broadside rolling Y so that the plate thickness of its end part in the longitudinal direction is larger than that of the central part in the same direction, to obtain a finished material SW in the broadside rolling. The material SW is further turned by 90 deg., to obtain a finished plate CP, having prescribed dimensions and less plate-width deviation in the longitudinal direction, by a finishing rolling Z.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for rolling thick plates.

[Prior art]

Table C for manufacturing thick plate products using a reversible rolling mill using slabs produced by continuous casting or a blooming mill.
, t=, generally three 1 I 1 as shown in Figure 2 '(
T? be exposed. First of all, the first step is rolling before tentering (II!
(Slab molded bath)
s 2J One direction refers to the longitudinal direction of the slab or finished plate,
Indicated by a double-headed arrow. The same applies hereafter) and roll the surface ilZ
A flattened niT rolled finished material SR is obtained.

Next, this is horizontally rotated 90 degrees and the second step is width adjustment! : [Enter the culm Y, and roll the tenter-rolled material 3B in the width direction of the sheet to obtain the tenter-rolled material 3B which has secured the required width. Next, it is horizontally rotated 90 degrees and enters the third step, finish rolling process Z, where the completed workpiece SW, which has reached 11 tenters, is rolled in the longitudinal direction of the plate and the required amount is rolled (counter-CP). obtain.

1. “The board width dimension of the finished plate cp, which is a C product, is finished to the target value, and the board width deviation in the longitudinal direction is
= Impressing 1 H force means that the side edge f in the later finishing process
:13 Kiriji P! ! ! ; It is a very important thing in the sense of increasing the yield by increasing the yield. In practice, it is extremely difficult to effectively suppress this plate 11 deviation, and although various methods have been explored in the past, no effective suppression method has yet been developed. The reality was that there was no such thing.

[Problem that the invention seeks to solve]

For example, by changing the roll spacing during tenter rolling, the cross-sectional shape of the tenter rolled thick plate in the longitudinal direction can be controlled;
A method for controlling the shape of a thick plate has been proposed (Japanese Patent Publication No. 17961/1983), which is characterized by controlling the planar shape of the plate after finish rolling, but skid marks are unavoidable on the rolled material. Therefore, as detailed below, the influence of skid marks occurs in the rolling process before tentering, and the above-mentioned Even if the technology were to be used, there would be no hesitation in finishing the ICP with a desirable shape.

One of the causes of the sheet width deviation mentioned above is the presence of skid marks. FIG. 3(A) is a plan view and a side view of the slab SL (referring to the drawing in which the longitudinal direction of the slab appears; the same applies hereinafter), and when heated in a continuous heating furnace, the part that contacts the skid rail is Due to the low temperature, blackened skid marks (indicated by the 2:1 line) appear. When this slab SL is rolled in the pre-tenting rolling process A tentered 1111 rolled completed material S8 as shown in Figure 3 (B) is obtained.Next, this is horizontally rotated by 9 () degrees and subjected to the tentering rolling process Y, where the skid marks exist and the other parts are removed. Due to the difference in the total rolling reduction amount between the two parts, the 1V and gourd-shaped tented rolled finished material SW as shown in Fig. 3 (c) was 1! Jru. Therefore, even when this is horizontally rotated by 90° and subjected to finish rolling process Z, as shown in Figure 3 (d), it has a gourd-shaped sheet width deviation as shown in Figure 3 (c), which is stretched out. This will be the finished plate CP.

Another major cause of the Saka 1st deviation is:
One example of this is that the IfA width of the material to be rolled is different between the center and the ends of the material. That is, the restraining force from the surrounding materials is different between the center and the ends, and the behavior of the material during rolling is different between the center and the ends, resulting in a 1-in width deviation. The plate width deviation due to this cause becomes more pronounced as the material becomes thicker and as the material@/material thickness ratio decreases.

FIGS. 4(a) to 4(d) schematically show how board width deviations appear in the finished board due to the above-mentioned causes.

First, when the slab SL shown in Fig. 4 (a) is rolled in the pre-tenting rolling process , a pre-tenting rolling completed material SB as shown in FIG. 4(b) is obtained, and when this is tentering rolled (Y), the slightly thick center part in the longitudinal direction of the plate is elongated. A finished piece of flattened rolled material as shown in (C) is obtained, and when it is finished rolled (Z), both ends and the center part in the horizontal direction of the machine length are widened, as shown in Fig. 4 (D) where the sheet width deviation is large. Finished plate CP shaped like a drum
will be obtained.

Now, in order to avoid the occurrence of sheet width deviation due to the skid marks mentioned above, it is sufficient to obtain a flat rolled material S8 before tentering. Because the mechanisms are different, a phenomenon that causes sheet width deviation occurs in the tentering rolling process X. That is, when a flat pre-tenting rolled completed material SB' having a rectangular planar shape as shown by the broken line in FIG.
b) In the same way as the process shown by the solid line in 5 (1), the plate length locally increases at both tm edges in the longitudinal direction (width direction) of the rolling direction (width direction of the plate), and ) A widened T1-rolled material SH' as shown by the broken line in FIG. A deviation of one margin will appear.

[Means for solving problems]

For this reason, in the present invention, Ff etc. adjust the rolling position in the rolling process X before tentering in order to minimize the Fi width deviation, thereby making the thickness distribution in the longitudinal direction of the thick plate uniform. It is effective to roll the completed rolled material before tentering, such as l&I'7. due to skid marks. In addition, during the tentering rolling process, the YL bottom is rolled by vertical rolling in the slope direction at a pre-calculated reduction so that the end of the thick plate in the horizontal direction becomes thick. hl! It has been found that the most effective way to minimize sheet width deviation is to

The present invention was made based on such knowledge,
Width ratio i: In plate rolling including the J rolling process and the width ratio rolling process, in order to reduce the plate width deviation after width ratio rolling, at least one bath of the width ratio pre-rolling process is performed. ,
In order to change and adjust the rolling position based on the deformation resistance of the thick plate and changes in the entrance thickness, and to reduce the width deviation of the plate in each width rolling process, the longitudinal end of the thick plate is adjusted during the width rolling process. It is characterized in that the thick plate is rolled down in the longitudinal direction of the plate using a vertical pressure t=m so that the thickness of the plate is larger than that of the central part in the longitudinal direction of the plate.

〔Example〕

The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a schematic block diagram showing the implementation state of the method of the present invention. In FIG. A load cell 3 for detecting, a rolling position detector 4 for detecting the rolling position (roll gap), a hydraulic rolling machine (R5, and a roll-down machine such as R5, etc.)
It is equipped with an arithmetic unit 6 for calculation and control. Also, 7 is
Width ratio 1 & -1, i"1! ζ, b Width ratio pre-rolling process, installed in front of any bus in the rolling process, using a vertical rolling mill, 8 is Sonoura j] The edger 7 is a rolling mechanism in which the edger 7 compares the width and rolls the rolling part in the rolling process (e) in the horizontal direction of the plate using hydraulic reduction #lJ horizontal 8 so that the edge in the longitudinal direction of the plate becomes thick. al eThe flow of information for plate width control is as shown by arrows in the drawing: load cell 3, rolling position detection: ; (Respective detection information is input from 4 to computing unit 6; Drive control information is output from the rolling tMI to the hydraulic rolling mechanism 5 in the rolling tMI and the hydraulic rolling mechanism 8 in the edger 7.

Then, in the final bus of pre-rolling, the width ratio to the slab SL is determined based on the 111 report regarding the rolling position S from the rolling position detector 4 and the output report regarding the rolling load P from the load cell 3. Below the so-called gauge meter thickness ha, ¥L! il
1 Jt) by the calculator 6.

1+++-3+ P/M...
・flllllL ~ 1: Mill rigidity By manipulating the rolling position in the final bath so that this plate thickness ha remains constant over the entire length, a pre-rolled completed material SR with no change in plate thickness in the longitudinal direction of the plate can be obtained. .

That is, in the above control process, the distribution of the deformation resistance and entrance thickness of the thick plate in the longitudinal direction of the thick plate mainly due to the presence of skid marks, in other words, the change in the deformation resistance and the entrance thickness in the longitudinal direction of the thick plate are controlled. , based on the rolling load tn information obtained from the load cell 3, is recognized by the machine 6, and is used as the gauge meter thickness ha at each location in the longitudinal direction of the plate to compare the width and control the rolling position in the previous rolling process X. will be reflected in

Next, a method for removing the sheet width deviation caused by the difference in deformation behavior between the center portion and the end portion (in the rolling width direction (longitudinal direction of the finished product)) during the width ratio rolling process will be described. This method is
In the width ratio rolling process, while rolling the plate to a predetermined width, rolling is performed in the longitudinal direction of the plate in one vertical rolling so that the edges in the longitudinal direction of the plate are thickened. . In other words,
In the above-mentioned 4, the influence of skid marks is avoided by making the plate thickness distribution uniform in the widthwise pre-pumping process. The reduction in the dimension in the rolling direction of the rolling width direction end (longitudinal end of the plate) caused by the difference in deformation behavior between
Each time the end portion in the longitudinal direction of the plate is made thicker, the thickness is increased by 14.

In this case, the amount of reduction in the longitudinal direction is calculated as L! J
,−,reru.

(]), First of all, the difference ΔW between the width of the edge of the plate CP and the width of the center of the plate CP (width of the edge - width of the center) The plate width (-2ΔB' in FIG. 4) is calculated using the empirical formula shown in equation (2) below.

Ill, α, Ij-r: coefficient G (value obtained by thoroughly soaking the slab in a hatch-type heating furnace and rolling the material with no skid marks) α, γ〉0, β〉0 Δhx: Total rolling reduction product (average value) in pre-tenting rolling process , then the difference Δ between the width of the finished plate cp at the end and the width of the center when the plate is rolled down in the longitudinal direction by F.
Find Wε (-2ΔB' in FIG. 4). First, plate #A (g difference ΔWE obtained when horizontal rolling is performed to flatten the thick wall portions at both ends produced by rolling down the plate in the longitudinal direction using the edger 7) is calculated using the following equation (3). Calculate the quasi-determinant using the experimental formula shown.

a, b: Coefficient Width deviation ΔW' when the plate is rolled down in the horizontal direction of the plate by the encoder 7 is the width deviation ΔW when the plate is not rolled in the horizontal direction given by equation (2), and The sum of the deviations ΔWE of the plate in one horizontal rolling with one tod in the width direction by the edger 7, that is, the following (4
) is expressed by the formula.

ΔW'=ΔW+ΔWE...(4)
Now, considering the case where the strip width deviation ΔW' is O when the edger 7 rolls down the strip in the longitudinal direction, (
4) The formula is as follows.

ΔWE =-ΔW (5)
Substituting equation (3) into equation (5), we can see that if the reduction is performed by the amount of reduction Δ■ in one hand direction of the plate expressed by equation (6), no deviation in plate width will occur. I
IIL, due to this reduction amount, the pressure T” in the plate longitudinal direction
1. If II fl cannot be performed, IK within the permissible range.
l; The lower liquid for manual direction Δ■ may be determined.

The timing of rolling down in the slope direction depends on workability.

Taking rolling efficiency into consideration, this step may be carried out in step iii+d of any bus during the tentering rolling process.

The dimensions in Figure 5 are 212sa (plate thickness) x 1800fl
(Plate @) x 22008m (plate length) slab with completed rolling dimension before tentering of 170mm (plate thickness) x 1800
+n (plate width)
(Plate width) X2473fl (Plate length), finished product size is 7.5
mm (plate thickness) x3078im CJli width) x3
The results of actually measuring the deviation of the width of the finished sheet when the method of the present invention was carried out with the rolling reduction amount in one direction of the sheet being 40 t and when the sheet was not controlled, in order to roll the sheet to 6.4 m (sheet length). They are shown by solid lines and broken lines, respectively. As is clear from these results, in the case of the present invention, the plate width deviation was drastically reduced, proving the nuisance of the method of the present invention.

〔effect〕

In the case of the present invention, the width deviation of the finished plate CP in the plate longitudinal direction is significantly suppressed in the SL history of the finished plate after tentering rolling, and the amount of side edge truncation in the finishing process can be reduced. This makes it possible to significantly improve the yield, and the present invention greatly contributes to the improvement of this type of rolling technology.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the implementation state of the method of the present invention, and FIG.
FIG. 3 is an explanatory diagram of thick plate rolling, FIGS. 3 and 4 are explanatory diagrams of the /J-forming process of handling lN11 deviation, and FIG. 5 is a graph showing the results of carrying out the method of the present invention. ]...Concession pressure 1j machine 2...Distance meter 3...Load cell 4...Driving down (page q detector 5.8...Hydraulic pressure down mechanism 6...Distance meter 7. ...Eng, Ja No. 3vj: J CP Nin 5B' No. 4 Sand- Ni==ko =-1-------Niji figure

Claims (1)

[Claims] 1. In plate rolling including the pre-tenting rolling process and the tentering rolling process, in order to reduce the plate width deviation after sweeping rolling, at least one bus of the pre-sweeping rolling process,
In order to change and adjust the rolling position based on the deformation resistance of the thick plate and changes in the entrance thickness, and to reduce the width deviation after sweeping rolling, the thickness of the longitudinal end of the thick plate is changed during the sweeping rolling process. A method for rolling a thick plate, characterized by applying a reduction in the longitudinal direction of the plate using a vertical rolling mill so that the reduction is greater than the center part in the longitudinal direction of the plate.