Method of plate rolling and equipment therefor

This invention relates to a method of plate rolling, wherein, in plate rolling, a value corresponding to the difference in width between the center and the end portions of a material to be rolled is estimated and calculated, sizing rolling is carried out by subjecting the material to plate rolling of plan view pattern control only at the opposite end portions thereof with a difference in gap between upper and lower work rolls in the axial direction thereof corresponding to said value, and to an equipment for use in said method.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvements in a method of plate rolling with a 
plate mill and an equipment therefor, and particularly to a method of 
plate rolling of plan view pattern control and an equipment therefor. 
2. Description of the Prior Art 
In general, in the case a rolling width is larger than the width of a slab 
to be rolled, a rolling in the transverse direction to the axis of the 
final rolling, i.e., a broadside rolling is effected to obtain a required 
rolling width, and thereafter, a rolling in the longitudinal direction, 
i.e., a final rolling to obtain a required rolling thickness. 
However, at this time of broadside rolling, a difference in width between 
the opposite end portions and the center of the plate (hereinafter 
referred to as a "side crop") is produced, and it is known that this side 
crop is increased in proportion to the increase in a broadside rolling 
ratio (rolling width/material width) as shown in FIG. 1. 
If the side crop as described above is increased, then problems such as 
misshaping and the like are caused to the plate after the rolling, thus 
causing a decrease in the yield. 
Now, as the methods of decreasing the side crop as described above, 
heretofore, there have been proposed (1) a method wherein corners of 
opposite end portions of a plate are bulged out by effecting a rolling in 
the longitudinal direction (sizing pass) before a broadside rolling, and 
thereafter, a broadside rolling is effected in the transverse direction so 
as to decrease the side crops, (2) a method wherein roll crowns are formed 
into minus crowns, whereby the reduction at the central portions is 
decreased as compared with that at the opposite end portions of the plate 
after the broadside rolling, so as to decrease the side crops, and the 
like. 
In the conventional method (1), if the reduction of the sizing pass is 
increased before the broadside rolling, then the side crop may be 
decreased, however, the reduction will be restricted. More specifically, 
the rolling width after the broadside rolling will be given by the 
following equation (1), thereby limiting the reduction of the sizing pass 
due to the length of roll barrel. 
EQU Rolling width after broadside rolling=Slab length.times.Slab 
thickness/(Slab thickness-reduction of the sizing pass)&lt;Length of roll 
barrel (1) 
Furthermore, in the aforesaid conventional method (2), it is necessary to 
form the roll crowns into minus crowns in accordance with the side crop. 
On the other hand, since the side crop is varied according to the 
broadside rolling ratio, it is necessary to prepare rolls having various 
types of roll crowns. Futher, even if the rolls having various types of 
roll crowns are prepared, roll profiles are varied due to wear of rolls, 
so that it is very difficult to obtain proper side crops. 
SUMMARY OF THE INVENTION 
The present invention has been developed to obviate the abovedescribed 
disadvantages of the prior art and has as its object the provision of a 
method of plate rolling and an equipment therefor, in which the production 
of side crops in plate rolling and the misshaping of the plate are 
eliminated to improve the yield. Further, another object of the present 
invention is to provide numerical formulae to determine the inclinations 
of the rolles for plate rolling of plan view pattern control (hereinafter 
referred to as the "plate rolling of the invention") to decrease the 
occurrence of side crops. 
To accomplish the abovedescribed objects, the method of plate rolling of 
the invention is characterized by rolling only on the opposite end 
portions, with a difference in gap between the upper and lower work rolls 
in the axial direction thereof corresponding to the difference in width 
between the center and the opposite end portions of the plate. 
More specifically, according to the present invention, a gap between the 
upper and lower work rolls in the axial direction thereof is varied by the 
value corresponding to the side crop, whereby the opposite end portions 
(the opposite end portions in the widthwise direction after broadside 
rolling) of the plate are decreased in thickness by the value of the side 
crop, so that the opposite end portions of the plate can be more 
broadside-rolled by a value as much as the side crop, thus enabling to 
decrease the side crop. Additionally, the positioning of screws for 
varying the gap between work rolls in the axial direction thereof is 
effected by a process computer for taking into account the side crop, 
barrel shape, reduction of the sizing pass, roll profiles (roll wear and 
thermal expansion) and the like, so that the abovedescribed disadvantages 
of the prior art (1) and (2) can be obviated at all. 
Furthermore, the plate rolling equipment according to the present invention 
is characterized by: 
upper and lower work rolls; 
reduction screws for applying reduction forces to roll chocks of said upper 
work roll; 
gears connected to said reduction screws; 
motors connected to said gears; 
encoders connected to said gears through reduction position meters; 
automatic reduction setting devices connected to said encoders; 
a process computer connected to said automatic reduction setting meters; 
and 
a reduction control system connected to said motors, said automatic 
reduction setting devices and said process computer. 
As described above, according to the present invention, the side crop of a 
material to be rolled for plate rolling is decreased to a large extent, so 
that the yield can be improved to a considerble extent, and moreover, 
misshaping and the like of the plate can be effectively prevented from 
occurring.

DETAILED DESCRIPTION OF THE INVENTION 
Description will hereunder be given of the present invention with reference 
to an embodiment shown in the drawings. 
Firstly, according to the present invention, as shown in FIG. 2, the first 
step is calculation of a roll gap difference (a difference in position 
.DELTA.So between the right and left screws of the rolls and an angle 
.alpha. of the upper work roll) in the axial direction between the work 
rolls commensurate to the side crop and the convex shape of the material 
10 to be rolled for the plate rolling of the invention. Next, the second 
step is calculation of a value (.DELTA.t as shown in FIG. 2) to be 
decreased commensurate to the side crop of the material 10 to be rolled. 
Further, the third step is to subject one end portion of the material to 
be rolled in the widthwise direction to the plate rolling of the invention 
(the rolling by inclining rolls after broadside rolling or that after 
sizing rolling) after determining the positions of the screws for the work 
rolls based on the calculations obtained in said first and second steps. 
Then, the fourth step is to subject the other end portion of the material 
to be rolled to the plate rolling of the invention after determining the 
positions of the screws for the work rolls based on the calculations 
obtained in said first and second steps. Finally, the fifth step is to 
turn the material 10 to be rolled through 90.degree., subject same to 
rolling perpendicularly to the direction of the plate rolling of the 
invention and further subject same to the sizing rolling to eliminate the 
difference in thickness caused by the plate rolling of the invention. 
Additionally, in the case calculation is actually made on the positions of 
the screws for the work rolls, said first and second steps are 
simultaneously carried out. 
Description will hereunder be given of calculation of the positions of the 
screws for the work rolls with reference to FIGS. 2 and 3. 
Firstly, a difference in gap between the upper and lower work rolls in the 
axial direction thereof, i.e., a difference in position .DELTA.So between 
the right and left screws of the rolls and an inclination .alpha. of the 
upper work roll from the horizontal direction are given from .DELTA.DEC by 
the following equation. 
##EQU1## 
wherein 
.DELTA.So: a difference in position between the right and left screws for 
the rolls (mm), 
So: positions of the screws immediately after broadside rolling (mm), 
GM: a thickness of the material immediately after broadside rolling (mm), 
l: a length of the material to be rolled immediately after sizing rolling 
(mm), 
.beta.: a side crop correction factor (experimentally, about 12% of l upon 
completion of the broadside rolling), and 
L: a distance between the centers of the roll bearings. 
Furthermore, the difference .DELTA.So in position between the right and 
left screws for the rolls may be given from the abovementioned equation 
(2) as shown below. 
##EQU2## 
Further, from .DELTA.DGF, it leads to the following. 
##EQU3## 
Further, from FIG. 3, a required value .DELTA.t to be decreased from the 
end portion of the material 10 to be rolled during the plate rolling of 
the invention is given by the equation (5) as shown below. 
Here, FIG. 3 is a view showing the convex shape assumed upon completion of 
the broadside rolling of the material to be rolled. 
##EQU4## 
wherein 
Ws: a width of the material to be rolled immediately after broadside 
rolling, and 
t: a thickness of the material to be rolled upon completion of the 
broadside rolling. 
From the abovementioned equations (3), (4) and (5), .DELTA.So may be given 
as shown below. 
##EQU5## 
Further, from the equations (4) and (5), it leads to the following. 
##EQU6## 
At the right sides of the abovementioned equations (6) and (7), the side 
crop .DELTA.W is varied depending upon the changes in the broadside 
rolling ratio, in the reduction of sizing pass and in the roll profile. 
However, .DELTA.W is stored in the process computer as a function in the 
following equation (8), so that .DELTA.So in the aforesaid equation (6) 
and .alpha. in the equation (7) can be automatically calculated by the 
process computer. 
##EQU7## 
wherein 
W.sub.r : a required rolling width (mm), 
W.sub.r /Ws: a broadside rolling ratio, 
.DELTA.Ts: a reduction of sizing pass (mm), and 
.DELTA.R: a varied value in the roll profile. 
Description will hereunder be given of the changes in the material to be 
rolled and in the plate in the process of the plate rolling according to 
the present invention with reference to FIG. 5 
(1) Numeral signs 1, 2, 3 and 4 are assigned to the corners of the end 
portions of the material 10 to be rolled as shown in FIG. 5(A). If the 
material 10 to be rolled as described above is subjected to the sizing 
rolling in the directions indicated by arrows in FIG. 5(B), then the 
corners 1, 2, 3 and 4 of the end portions of the material 10 to be rolled 
will bulge out as shown. In this case, the bulgings of the corners 1, 2, 3 
and 4 of the end portions take place very naturally under the sizing 
rolling. 
(2) Next, when the required rolling width is obtained by carrying out the 
broadside rolling in the directions indicated by arrows in FIG. 5(C), the 
lines between 1 and 4 and between 2 and 3 out of the corners of the end 
portions of the material 10 to be rolled bulge out to provide convex 
shapes as shown. 
(3) Subsequently, the end portions of the material 10 to be rolled are 
subjected to the plate rolling of the invention according to the present 
invention. In this case, out of two work rolls including the upper work 
roll 11 and the lower work roll 12 for rolling the material 10, the work 
rolls effects the plate rolling of the invention of the end portions in 
the axial direction of the material 10 in a condition where the upper work 
roll 11 is inclined by the difference in angle .alpha. in the axial 
direction corresponding to the side crop with the difference in position 
between the right and left screws being .DELTA.So as shown in FIG. 4. In 
the plate rolling of the invention, squares 1265 and 4378 at the end 
portions of the material 10 are subjected to the plate rolling of the 
invention in the directions indicated by arrows in FIG. 5(D), whereby the 
square 1265 is turned to be one 1'2'65 and the square 4378 is turned to be 
one 4'3'78, thus enabling to obviate the problem of the convex shape. 
(4) Thereafter, the material 10 is subjected to a final rolling to have a 
required plate thickness as indicated by arrows in FIG. 5(E), so that a 
plate being of a square 1'2'3'4' without having a convex shape can be 
obtained. 
AN EXAMPLE 
Next, Table 1 shows the results of the rolling the material for plate 
rolling in accordance with the abovedescribed procedural steps followed by 
the present inventor. It becomes apparent from this Table 1 that, 
according to the present invention, it is possible to efficiently roll out 
a plate without having a convex shape. 
The present invention is characterized in that, in the plus area of the 
side crop as shown in FIG. 1, the work rolls are inclined to each other by 
the value corresponding to the difference in side crop upon completion of 
the broadside rolling or before the broadside rolling, so that the end 
portions of the material 10 can be decreased in thickness under the plate 
rolling of the invention. This side crop is a function of the broadside 
rolling ratio, of the reduction of sizing rolling and of the roll profile 
as shown in the abovementioned equation (8). According to the present 
invention, this function is applied to the abovementioned equation (6) in 
carrying out the rolling with the difference in gap between the work rolls 
in the axial direction thereof corresponding to the difference in side 
crop, so that a loss ratio in area due to the side crop can be made to 
approach zero even if the material has the side crop and is of a convex 
shape. (loss ratio in area due to the 
##EQU8## 
TABLE 1 
__________________________________________________________________________ 
POSITIONS 
OF SCREWS 
UPON DIFFER- 
COMPLETION 
ENCE 
BROADSIDE 
REDUCTION 
OF IN GAP 
DIMENSIONS OF ROLLING OF SIZING 
BROADSIDE 
BETWEEN 
MATERIAL TO BE 
DIMENSIONS OF 
RATIO ROLLING ROLLING ROLLS 
ROLLED ROLLING (Wr/Ws) (.DELTA.Ts) 
(t) (.DELTA.So) 
EXAMPLE mm mm mm mm mm mm 
__________________________________________________________________________ 
EXAMPLE 200 .times. 1900 .times. 3060 
11.17 .times. 3764 .times. 24800 
1.98 21.5 85.5 16.1 
(1) 
COMED 
200 .times. 1900 .times. 3060 
11.17 .times. 3764 .times. 24800 
1.98 22.0 85.1 0 
MATERIAL 
IN 
EXAMPLE 
(1) 
EXAMPLE 200 .times. 1894 .times. 3240 
12 .times. 3048 .times. 30480 
1.61 6.4 117.2 11.7 
(2) 
COMED 
200 .times. 1894 .times. 3230 
12 .times. 3048 .times. 30480 
1.61 7.0 115.6 0 
MATERIAL 
IN 
EXAMPLE 
(2) 
__________________________________________________________________________ 
DISTANCE 
SIDE CROP BETWEEN 
MEAN CENTERS 
ACTUAL 
ACTUAL 
LOSS OF ROLL 
SIDE SIDE RATIO BEARINGS 
CROP CROP OF AREA 
(L) 
EXAMPLE mm mm % mm Remarks 
__________________________________________________________________________ 
EXAMPLE 55 33 0.82 4320 50 kg 
(1) steel 
COMED 
121 100 2.55 " 50 kg 
MATERIAL steel 
IN 
EXAMPLE 
(1) 
EXAMPLE 43 20 0.65 " 40 kg 
(2) steel 
COMED 
56 41 1.31 " 40 kg 
MATERIAL steel 
IN 
EXAMPLE 
(2) 
__________________________________________________________________________ 
In the case of the abovedescribed embodiment, the plate rolling of the 
invention for correcting the difference in side crop is carried out upon 
completion of the broadside rolling. However, it is possible that, before 
the broadside rolling is carried out, the possible side crop, which would 
be produced during broadside rolling, is estimated in advance, and the 
opposite end portions of the material is subjected to the plate rolling of 
the invention to be decreased in thickness, so that the production of side 
crop, which would otherwise be observed due to the broadside rolling and 
the like, can be controlled within the tolerance limit. FIGS. 6(A) to 6(F) 
show an embodiment of he present invention in that case, which will be 
described hereinafter. In this case also, the abovedescribed equations (2) 
to (8) can be utilized for calculation of the required decrease in 
thickness for the plate rolling of the invention, the difference in gap 
between the work rolls in the axial direction thereof and the like, and 
hence, the detailed description thereof will be omitted. 
(1) Also, in the case of this example, the corners of the respective end 
portions of the material 10 to be rolled are assigned with numeral signs 
1, 2, 3 and 4 as in FIG. 6(A). If the plate rolling of the invention is 
applied to the end portions of the material 10 as described above in the 
directions indicated by arrows in FIG. 6(B), then the corners 1, 2, 3 and 
4 of the end portions of the material 10 bulge out as indicated by 1', 2', 
3' and 4'. In this case, the two work rolls including the upper work roll 
11 and the lower work roll 12 for rolling the material 10, effect the 
plate rolling of the invention on the end portions of the material 10 (the 
portions outwardly of two broken lines in the longitudinal direction in 
FIG. 6(B) in a condition where the upper work roll 11 is inclined by the 
difference in angle .alpha. in the axial direction corresponding to the 
estimated side crop with the difference in position between the right and 
left screws being .DELTA.So as shown in FIG. 4. 
(2) Next, the sizing rolling in the directions indicated by arrows in FIG. 
6(C) is carried out, whereby the plate thickness reduced portions of the 
material 10 due to the plate rolling of the invention of the end portions 
are flattened in the longitudinal direction. 
(3) Further, the material 10 is subjected to the broadside rolling as shown 
in FIG. 6(D), thereby enabling to obtain a required rolling width. 
(4) Thereafter, the material 10 is subjected to the final rolling to a 
required plate thickness as indicated by arrows in FIG. 6(E), so that a 
plate being of a square 1', 2', 3' and 4' without having a convex shape 
can be obtained. 
ANOTHER EXAMPLE 
Next, Table 2 shows the results of the rolling the material for plate 
rolling in accordance with the procedural steps as described above and 
shown in FIGS. 6(A) to 6(E), which were followed by the present inventor. 
It becomes apparent from this Table 2 that, in the case of this example 
also, a satisfactory plate without having a convex shape can be obtained. 
Description will hereunder be given of the control system for carrying out 
the abovedescribed method according to the present invention. 
FIG. 7 is an explanatory view showing an example of the control system for 
carrying out the method according to the present invention. In FIG. 7, the 
material 10 to be rolled is under a condition where it is subjected to the 
plate rolling of the invention by the upper and lower work rolls 11 and 12 
in the same manner as in FIG. 4. Designated at reference numerals 13, 14 
are backup rolls, and 15, 16 roll chocks on the driving side and the 
operating side. 
TABLE 2 
__________________________________________________________________________ 
POSITIONS 
OF SCREWS 
UPON 
COMPLETION 
BROADSIDE 
REDUCTION 
OF 
DIMENSIONS OF ROLLING OF SIZING 
BROADSIDE 
MATERIAL TO BE 
DIMENSIONS OF 
RATIO ROLLING ROLLING 
ROLLED ROLLING (Wr/Ws) (.DELTA.Ts) 
(t) 
EXAMPLE mm mm mm mm mm 
__________________________________________________________________________ 
EXAMPLE 260 .times. 1700 .times. 3230 
36 .times. 3000 .times. 12192 
1.76 45 250 
(1) 
COMED 
260 .times. 1700 .times. 3230 
36 .times. 3000 .times. 12192 
1.76 45 -- 
MATERIAL 
IN 
EXAMPLE 
(1) 
EXAMPLE 200 .times. 1570 .times. 2960 
9 .times. 3048 .times. 30480 
1.94 30 190 
(2) 
COMED 
200 .times. 1570 .times. 2930 
9 .times. 3048 .times. 30480 
1.94 30 -- 
MATERIAL 
IN 
EXAMPLE 
(2) 
__________________________________________________________________________ 
DISTANCE 
DIFFERENCE BETWEEN 
IN GAP SIDE CROP CENTERS 
BETWEEN DEVIATION 
LOSS OF ROLL 
ROLLS IN RATIO BEARINGS 
(.DELTA.So) 
WIDTH OF AREA 
(L) 
EXAMPLE mm mm % mm 
__________________________________________________________________________ 
EXAMPLE 10 28 0.90 4320 
(1) 
COMED 
-- 72 2.31 4320 
MATERIAL 
IN 
EXAMPLE 
(1) 
EXAMPLE 10 23 0.71 4320 
(2) 
COMED 
-- 43 1.35 4320 
MATERIAL 
IN 
EXAMPLE 
(2) 
__________________________________________________________________________ 
A reduction control unit for applying reduction forces to the roll chocks 
15, 16 on the driving and operating sides includes a reduction control 
system 17, a process computer 18 for feeding an inclinated reduction 
signal to said reduction control system 17, automatic reduction setting 
devices (reduction APC) 19 and encoders 20. Furthermore, said reduction 
control system 17 is connected to two motors 23 on the driving and 
operating sides, which are connected through an electromagnetic clutch 22 
to each other, the both motors 23 are each connected to two gears 25, 26 
through a gear 24, one 25 of the gears is connected to a reduction screw 
27 for applying a reduction force to the roll chock 15, and the other 26 
of the gears is connected to the encoder 20 through a reduction position 
sensor 28. 
Description will hereunder be given of operation of said control unit. 
Firstly, reduction positions at the driving and operating sides are 
calculated by the process computer 18 as shown in FIG. 8. The process 
computer 18 feeds an inclined reduction signal to the reduction control 
system 17 based on the result of the aforesaid calculation. Upon receipt 
of the signal, the reduction control system 17 turns off the 
electromagnetic clutch 22, and at the same time, feeds a clutch turn-off 
completion signal to the process computer 18. Upon receipt of said clutch 
turn-off completion signal, the process computer 18 feeds a reduction 
setting value to the automatic reduction setting devices at the driving 
and operating sides, respectively. The respective automatic reduction 
setting devices 19 compare the reduction setting value from the process 
computer 18 and the actual reduction positions from the reduction position 
sensors 28 and the encoders 20 and feed the deviation to the reduction 
control system 17 so as to control the reduction positions to coincide 
with the setting positions. Upon completion of this control, a required 
reduction screw 27 at either the driving side or the operating side is 
driven by the motor 23 to press down one of the roll chocks 15, whereby 
the work roll 11 is inclined so that a difference can be given in roll gap 
between the work rolls 11 and 12 in the axial direction. Under this 
condition, the end portion at one side is subjected to a one-side plate 
rolling by the invention, and thereafter, the end portion at the other 
side is subjected to the one-side plate rolling by the invention similarly 
to above. Further, if the opposite end portions at the other surface are 
subjected to the plate rolling of the invention similar to the above, then 
the material 10 having a satisfactory shape of plate rolling of the 
invention as shown in FIG. 9 is obtainable. 
It should be fair to state that any reduction control unit other than that 
described above may be used. 
In addition, the value for plate rolling of the invention at each end 
portion at each side surface of the material 10 may be separately 
controlled according to the requirement. 
Furthermore, the present invention is applicable to the rolling in which 
the axis of the material to be rolled is made to be the rolling width (a 
so-called rolling in the transverse direction). More specifically, under 
the same idea as in the ordinary rolling in the longitudinal direction, 
the plate rolling of the invention is carried out with the difference in 
gap between the work rolls in the axial direction thereof corresponding to 
the difference in side crop upon completion of the broadside rolling or 
before the broadside rolling, so that the side crop can be decreased. 
Further, in the case the material has a widthwise tapered shape in the 
longitudinal direction, if the broadside rolling is carried out, then the 
difference in width remain as they are. However, according to the present 
invention, with the material as described above, the plate rolling of the 
invention is carried out with the difference in gap between the work rolls 
in the axial direction thereof corresponding to the difference in width 
upon completion of the broadside rolling or before the broadside rolling, 
so that the difference in width as described above can be obviated. 
Further, in the case slabs are produced from an ingot in a slabbing mill, 
if the ingot has a widthwise tapered shape, then the slab is also has a 
difference in width in tapered-like shape under the influence of the 
ingot. However, the present invention is also effective in avoiding the 
abovedescribed difference in width. More specifically, in the process of 
slabbing rolling, the ingot is subjected to the rolling in the transverse 
direction relative to the axis of ingot, and at the same time, the plate 
rolling of the invention is carried out with the difference in gap between 
the work rolls in the axial direction thereof corresponding to the 
difference in width, so that the difference in width can be eliminated. 
From the foregoing description, it should be apparent to one skilled in the 
art that the abovedescribed embodiment is but one of many possible 
specific embodiments which can represent the applications of the 
principles of the present invention. Numerous and varied other 
arrangements can be readily devised by those skilled in the art without 
departing from the spirit and scope of the invention.