U.S. patent number 3,731,508 [Application Number 05/068,716] was granted by the patent office on 1973-05-08 for rolling of strip or plate material.
This patent grant is currently assigned to The British Iron and Steel Research Association. Invention is credited to Bruno Sabatini, Mahmoud Tarokh.
United States Patent |
3,731,508 |
Sabatini , et al. |
May 8, 1973 |
ROLLING OF STRIP OR PLATE MATERIAL
Abstract
Strip or plate material being rolled under symmetrical rolling
conditions is simultaneously corrected for gauge and shape errors
in a single integrated gauge and shape control system, by detecting
its gauge and shape upon leaving the rolling mill; expressing
detected shape as a defined combination of different curves and
deriving defined error signals from coefficients of the curves;
deriving an error signal from detected gauge; translating said
error signals into defined control signals; and feeding each
control signal to a respective one of a plurality of different
rolling mill control means.
Inventors: |
Sabatini; Bruno (Roma,
IT), Tarokh; Mahmoud (London, EN) |
Assignee: |
The British Iron and Steel Research
Association (London, EN)
|
Family
ID: |
10429681 |
Appl.
No.: |
05/068,716 |
Filed: |
September 1, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Sep 3, 1969 [GB] |
|
|
43,645/69 |
|
Current U.S.
Class: |
72/8.6; 72/9.1;
72/9.4 |
Current CPC
Class: |
B21B
37/18 (20130101); B21B 37/28 (20130101) |
Current International
Class: |
B21B
37/18 (20060101); B21B 37/28 (20060101); B21B
37/16 (20060101); B21b 037/02 () |
Field of
Search: |
;72/6-12,16,17 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mehr; Milton S.
Claims
We claim:
1. A method for controlling gauge and shape of strip and plate
materials in a single integrated gauge and shape control system
during rolling thereof in a rolling mill under symmetrical rolling
conditions, characterized in that the method includes detecting
gauge of said material leaving the mill; detecting shape of said
material leaving the mill; expressing the detected shape as a
combination of at least two curves of different geometrical form
defined by algebraic equations; deriving a gauge error signal from
the detected gauge; translating said gauge error and a coefficient
from each of the equations in combination into control signals
equal in number to the number of said coefficients plus said gauge
error for correcting simultaneously gauge and shape errors; and
feeding each control signal to a respective one of a plurality of
different mill control means to make simultaneous correction of
gauge and shape errors.
2. A method as claimed in claim 1, characterized in that gauge is
detected by an X-ray gauge (1) on the output side of the rolling
mill.
3. A method as claimed in claim 1, characterized in that gauge is
detected by a load cell (1) under rolling stand adjustment
screws.
4. A method as claimed in claim 1, characterized in that shape is
detected by a tension distribution meter (2).
5. A method as claimed in claim 4, characterized in that he tension
distribution meter (2) includes at least five probes, positioned at
spaced points across the strip or plate material leaving the
rolling mill and detecting tension in that material at those
points.
6. A method as claimed in claim 1, characterized in that the
plurality of different mill control means includes at least two
different mill control means chosen from rolling stand adjustment
screw control means (6), roll bending control means (7) and tension
control means (8).
7. A method as claimed in claim 6, characterized in that each of
said control means (6,7,8) is present.
8. Apparatus for controlling gauge and shape of strip and plate
materials during rolling thereof in a rolling mill under
symmetrical rolling conditions, characterized in that the apparatus
includes sensor means (1) for detecting gauge of said material
leaving the mill; sensor means (2) for detecting shape of said
material leaving the mill; a computer (4) for receiving the outputs
of the first and second sensor means and (a) expressing the
detected shape as a combination of at least two curves of different
geometrical form defined by algebraic equations, and providing at
least two signals representative of a coefficient of each equation,
and (b) deriving an error signal from the detected gauge; a
controller (5) for receiving said signals in combination and
translating them into control signals equal in number to the total
number of said signals and for correcting simultaneously gauge and
shape errors; and a plurality of different mill control means (6,
7, 8) for receiving at each respective one of the control means
each control signal to make simultaneous correction of gauge and
shape errors.
9. Apparatus as claimed in claim 8, characterized in that the
sensor means (1) for detecting gauge includes at least an X-ray
gauge on the output side of the mill.
10. Apparatus as claimed in claim 8, in which the sensor means (1)
for detecting gauge includes at least a load cell under rolling
stand adjustment screws.
11. Apparatus as claimed in claim 8, characterized in that the
sensor means (2) for detecting shape includes at least a tension
distribution meter.
12. Apparatus as claimed in claim 11, characterized in that the
tension distribution meter (2) includes at least five probes for
positioning at spaced points across the strip or plate material
leaving the mill and for detecting tension in that material at
those points.
13. Apparatus as claimed in claim 8, characterized in that the
plurality of different mill control means includes at least two
different mill control means chosen from rolling stand adjustment
screw control means (6), roll bending control means (7) and tension
control means (8).
14. Apparatus as claimed in claim 13, characterized in that each of
said control means (6,7,8) is present.
15. A method as claimed in claim 1 characterized in that said
coefficients and said gauge error are each expressible as a
function of control factors equal in number to said coefficients
plus said gauge error, and wherein said translating step comprises
calculating said control factors and providing said control signals
in response to each of said control factors.
16. A method as claimed in claim 1 characterized in that the said
equations are functions of X where X is the distance of a point on
the strip or plate from the longitudinal center line thereof.
17. A method as claimed in claim 16 characterized in that the said
equations are of the form F.sub.1 = K.sub.1 X.sup.2, F.sub.2 =
K.sub.2 X.sup.4 . . . F.sub.n = k.sub.n X.sup.2n.
18. A method as claimed in claim 1 characterized in that said
coefficients and said gauge error are each expressible as a linear
combination of control factors equal in number to said coefficients
plus said gauge error, and wherein said translating step comprises
calculating said control factors and providing said control signals
in response to each of said control factors.
19. Apparatus as recited in claim 8 characterized in that said
signals are each expressible as a function of control factors equal
in number to said total number of said signals, and wherein said
controller generates said control factors and provides said control
signals corresponding to each control factor.
20. Apparatus as recited in claim 8 characterized in that said
signals and gauge error signal are each expressible as a linear
combination of control factors equal in number to said total number
of signals, and wherein said controller generates said control
factors and provides said control signals corresponding to each
control factor.
Description
This invention relates to rolling of strip or plate material. Strip
material includes sheet material.
Modern requirements for flat roller strip or plate material make it
desirable to control the rolling operation so that the product has
the desired thickness (namely the correct gauge) and is free from
buckles and internal stresses (namely is of good shape). Separate
control of gauge and shape has not been practical because of their
interacting nature. For example, a gauge correcting action by
rolling stand screw adjustment has an effect on shape,
Alternatively, as another example, a shape correcting action on
roll bending control means or strip tension control means has an
effect on gauge. Depending on the degree of interaction between
gauge and shape, control of the rolling operation with separate
control means for gauge and shape, once initiated, may take a long
time or never be achieved.
It has now been found in accordance with the present invention that
simultaneous control of gauge and shape of strip or plate material
may be provided to obtain strip or plate material of desired
thickness and shape.
According to one aspect of the present invention, a method for
controlling gauge and shape of strip or plate material during
rolling thereof in a rolling mill under symmetrical rolling
conditions includes detecting gauge of strip or plate material
leaving the mill; detecting shape of strip or plate material
leaving the mill; expressing the detected shape as a combination of
at least two curves of different geometrical form and deriving at
least two error signals from the coefficients of the curves, each
error signal corresponding to a respective one of the coefficients;
deriving an error signal from the detected gauge; translating said
error signals into control signals equal in number to the number of
error signals and for correcting simultaneously gauge and shape
errors; and feeding each control signal to a respective one of a
plurality of different mill control means to make simultaneous
correction of gauge and shape errors.
According to another aspect of the invention, apparatus for
controlling gauge and shape of strip or plate material during
rolling thereof in a rolling mill under symmetrical rolling
conditions includes sensor means for detecting gauge of strip or
plate material leaving the mill; sensor means for detecting shape
of strip or plate material leaving the mill; a computer for (a)
expressing the detected shape as a combination of at least two
curves of different geometrical form and deriving at least two
error signals from the coefficients of the curves, each error
signal corresponding to a respective one of the coefficients, and
(b) deriving an error signal from the detected gauge; a controller
for translating said error signals into control signals equal in
number to the number of error signals and for correcting
simultaneously gauge and shape errors; and a plurality of different
mill control means for receiving at each respective one of the
control means each control signal to make simultaneous correction
of gauge and shape errors.
The sensor means for detecting gauge may be or include an X-ray
gauge on the output side of the rolling mill. Alternatively or
additionally, the sensor means may be or include a load cell under
rolling stand adjustment screws. The sensor means for detecting
shape may be or include a tension distribution meter. Preferably,
the meter is one described in our U.K. Pat. specification No.
1,138,822. This meter includes at least five probes for positioning
at spaced points across the strip or plate material leaving the
rolling mill and detecting tension in that material at those
points. The gauge and shape sensor means may be located above
and/or below the strip or plate material leaving the rolling mill.
The choice will be according to the circumstances. Each sensor
means should be as close as possible to the rolling mill.
The gauge and shape errors at a point distant x from the mid-width
line of the material measured transversely thereof are components
of the total profile error E(x) of the strip or plate material at
that point. E(x) may be expressed in accordance with the present
invention by equation 1:
E(x) = E.sub.c + F.sub.1 (x) + F.sub.2 (x) . . . + F.sub.n (x).
(1)
in which
a. E.sub.c is the total profile error at the mid-width line where x
is 0. E.sub.c represents the gauge error component, from which
preferably one error signal may be derived by a computer.
b. F.sub.1 (x) + F.sub.2 (x) . . . +F.sub.n (x) are homogenous
functions of x, chosen on the basis of theoretical and practical
considerations to obtain a description of E(x) sufficiently
accurate for practical purposes.
For symmetrical rolling conditions, which are the conditions
required by the present invention, the total profile error E(x)
will be symmetrical about the mid-width line of the strip or plate
material. If there should be assymmetry in E(x), symmetry can be
provided by differential movement of rolling stand adjustment
screws, in which one screw is raised or lowered with respect to the
other screw. With E(x) symmetrical about the mid-width line, and on
the basis of theoretical considerations supported by measurement on
rolled material, the functions F.sub.1 (x) . . . F.sub.n (x) of
equation 1 may be represented as:
F.sub.1 = K.sub.1 x.sup.2
F.sub.2 = K.sub.2 x.sup.4 . . . F.sub.n = K.sub.n x.sup.2n
in which K.sub.1 . . . K.sub.n are constants. Thus, E(x) may then
be represented by equation 2:
E(x) = E.sub.c + K.sub.1 x.sup.2 + K.sub.2 x.sup.4 . . . + K.sub.n
x.sup.2n ( 2)
In this equation, the terms K.sub.1 x.sup.2 . . . K.sub.n x.sup.2n
represent the component of shape error in n dimensions under
symmetrical rolling conditions. This may be called the symmetrical
component of shape error in n dimensions. Thus, the control of
gauge error and shape error will be provided by the elimination of
(n + 1) error parameters, namely E.sub.c, K.sub.1, K.sub.2 . . .
K.sub.n. These parameters depend on the adjustable parameters of
the rolling mill, for example the positions of rolling stand
adjustment screws, rolling tension and roll bending force. For
practical purposes, it is generally sufficient to consider the
component of shape error as the simpler equation 3:
Shape error component = K.sub.1 x.sup.2 + K.sub.2 x.sup.4 ( 3)
Given equations 2 and 3, the components of shape error (for one or
more transverse positions x of the material) may be expressed as a
combination of at least two curves of different geometrical form.
Therefore, shape error may be expressed in terms of at least the
two coefficients K.sub.1, K.sub.2. At least two error signals may
then be derived by a computer from these coefficients.
A mill control means may serve to control for example position of a
roll adjustment screw, S; roll bending force, J; front rolling
tension, Tf; or back rolling tension, Tb. Small changes .DELTA.S,
.DELTA.T, .DELTA.J in these controlling factors cause linearly
related changes in the error parameters E.sub.c, K.sub.1, K.sub.2 .
. . K.sub.n. These changes for the case of equation 3 above are
expressed by the equations 4:
E.sub.c = a.sub.1 .DELTA.S + a.sub.2 .DELTA.T + a.sub.3
.DELTA.J
K.sub.1 = a.sub.4 .DELTA.S + a.sub.5 .DELTA.T + a.sub.6
.DELTA.J
K.sub.2 = a.sub.7 .DELTA.S + a.sub.8 .DELTA.T + a.sub.9 .DELTA.J
(4)
In which a.sub.1, a.sub.2 . . . a.sub.9 are constants referred to
as Mill Parameters. These parameters may be determined
theoretically or experimentally. They measure the sensitivity of
the corresponding error parameters E.sub.c, K.sub.1, K.sub.2 . . .
K.sub.n to the controlling factors .DELTA.S, .DELTA.T, .DELTA.J.
Control signals corresponding to .DELTA.S, .DELTA.T, .DELTA.J may
be produced by a controller translating error signals from a
computer as described above. The control signals may then be fed to
the plurality of mill control means.
The plurality of mill control means preferably includes rolling
stand adjustment screw control means; roll bending control means;
or, especially when strip material is being processed, tension
control means. Any combination of mill control means may be used.
Preferably for strip material, each of the specific mill control
means just mentioned may be used. Tension control means may control
a coiler and/or decoiler for strip material. Roll bending control
means may be provided by hydraulic jacks acting on the necks of
rolls in the mill.
A schematic embodiment of the present invention in accordance with
equation 3 above will now be described by way of example with
reference to the accompanying drawings wherein:
FIG. 1 is a diagrammatic side view of a rolling mill provided with
control apparatus according to the invention, and
FIG. 2 is an enlarged, fragmentary perspective view showing the
shape sensors feeding into the computer.
In the drawing, apparatus according to the invention includes a
gauge sensor 1 and a shape sensor 2 for detecting under symmetrical
rolling conditions gauge and shape respectively of strip material
leaving the rolls 3 of the rolling mill. The sensors may be located
above and/or below the material as required and as close as
possible to the rolling mill.
The gauge sensor 1 may be an X-ray gauge on the output side of the
rolls 3 or a load cell under rolling stand adjustment screws (not
shown). The shape sensor 2 may be a tension distribution meter.
Preferably, this meter is one described in our U.K. Pat.
specification No. 1,138,322, which includes at least five probes
for positioning at spaced points across the strip material leaving
the rolls 3 and for detecting the tension in that material at those
points.
The output signals of the sensor 1, 2 pass respectively into a
computer 4, programmed with the required gauge of the strip
material and the desired zero shape error. The computer derives an
output error signal from the output signal of the gauge sensor 1.
The error signal represents the gauge error coefficient E.sub.c.
The computer also expresses the output signal from the shape sensor
2 as a combination of two curves of different geometrical form, and
derives two output error signals, one for coefficient of each
curve. To do this, the computer employs standard curve-fitting or
regression techniques which are known in themselves to one skilled
in the art.
Each output error signal from the computer passes into a controller
5. The controller translates these signals in combination into an
equal number of output control signals, .DELTA.S, .DELTA.T,
.DELTA.J, by means of an algorithm based on equations 4. The
controller utilizes the mill parameters mentioned with reference to
the equations 4 and the time responses of the measuring device
together with any transport delays associated with them. Each
output control signal passes into a respective one of a plurality
of different mill control means. These means are respectively
rolling stand adjustment screw control means 6, to which the
.DELTA.S control signal is fed; roll bending control means 7, to
which the .DELTA.J control signal is fed; and tension control means
8, to which the .DELTA.T control signal is fed. These means may
operate simultaneously. The roll bending control means 7 control
rolling stand hydraulic jacks (not shown). The tension control
means 8 controls a decoiler 9 from which strip material passes into
the rolling mill. Alternatively or additionally, the means 8 may
control a coiler 10 which coils the product strip material. The
tension control means 8 could have been omitted if plate material
had been rolled instead of strip material.
The controller 5 enables simultaneous corrections for gauge and
shape to be implemented without undesirable interaction as would
occur with separate independent controls for gauge and shape.
* * * * *