Note: Descriptions are shown in the official language in which they were submitted.
This invention rela-tes to mill stands. It is more
particularly concerned with method and apparatus for calibrating
a stand both with respect to gauge and to flatness of product.
The invention is particularly well adapted ~or use with
mill stands provided with the closed loop integrated gauge and
crown control. Such equipment is disclosed in United States
Patent 4,054,043 of Werner W. Eibe, issued October 18, 1977.
In flat product mills for hot rolled plate and strip as
well as for cold rolled strip, the dimensional quality of the
produc~ depends on the accuracy of the roll gap between the
work rolls. Gauge is normally controlled by automatic gauge
control systems and the shape by separate roll crown control
systems, The most effective variable crown control system is
obtained by counter bending the mill rolls opposite their
deflection due to rolling forces. As far as crowning the rolls
is concernedr it has always been difficult to know that the rolls
are absolutely flat so that the product is also flat across its
width. With thin strip the flatness is mostly controlled by the
operatoris observation of buckles somewhere across the width.
Automatic devices have been conceived that measure the flatness
behind the mill, then make corrections to the roll bending
cylinders. In heavy plate rolling the shape can only be esta-
blished after the finishing pass by measuring the crown. In all
these cases it is an after-the-fact measurement and feedback to
the control system often resulting in out-of-tolerance non-
saleable material.
With regard to automatic gauge control, load cells have
been placed underneath the mill screws or the hydraulic piston
in case of hydraulic roll adjustment. Thei zeroing and
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levelling of the automatic gauge control system is normally
done by facing the slowly rotating work rolls under enough
pressure so that all the a~fected mill stand components are
stretched or compressed sufficien~ly to have a more or less
linear spring characteristic from there on. During this proce-
dure the work and back-up rolls would deflect due to roll bend-
ing, shear and ~lattening. In the present state of the art,
these sizeable deflections had to be neglected during the
calibratlon procedure. Only after the product was rolled the
shape problems became obvious and could only then be corrected
by manual or automatic control of the roll bending system.
It is an object of the invention to provide method
and apparatus for calibrating the roll gap in a mill stand both
for gauge and for shape flatness. It is ano-ther object to
utilize for that purpose electric or hydraulic transducers to
measure the pressure across the face of a roll in a mill stand
and so make possible the gap calibration. It i5 another object
to utilize -the signals from those transducers for actuating a
visible display. It is still another object to use those
signals as additional inputs into the gauge and control system
of a suitable mill control system.
The apparatus of the invention comprises a frame
carrying one or more transducers, the frame being dimensioned
so that it can be inserted between work rolls of a mill stand
with the transducers positioned parallel to the roll axis. The
outputs of the transducers are connected to a display device
which, when load is applied, displays the several output signals
side-by-side so that variation in loading ]engthwise of the rolls
is made visible. Those outputs are proportional to the width
of the roll gap at the positions of the respec-tive transducers.
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The outpu~s of at least the center transdu~er and ~ho ~wo transducers adjacent
the ends of a roll are also interconnected into ~he gauge and crown control
circuits of a mill con~rol sys~em so that th~se circuits can be calibrated
against the actual dimensions of the roll gap.
Thus, in accordance with one broad aspect of the invention, there is
provided apparatus for calibrating the gap betwcen work rolls of a rolling
mill stand comprising transducer m~ans for converting the width of gap into a
signal, frame means for mounting said transducer means, said rame means being
dimensioned for passage as a uni~ through the gap between work rolls and ex-
tending lengthwise of ~hose rolls so as to bring said transducer means againstthe work rolls at their line of cantact in load transmitting relation there-
between and for removal therefrom, and means for cond~cting *he signals from
said transducer means out of the gap.
According to another aspect of the invention ~here is provided the
method of calibrating for optimum flatness of the product a rolling mill stand
provided with pressure means for varying the crown of a work roll comprising
positioning in the hite of the work rolls transducer means adapted to convert
the wid~h of the gap into a signal, applying pressure to the work rolls, in-
dicating the signal from a transducer adjacent a work roll neck, appl~ing
crowning pressure to the work ~oll, indicating the signal f~om a transducer
centrally located along the roll, and adjusting those pressures until those
signals are equal.
In accordance with another aspect of the invention there is provided
the method of calibrating for optimum flatness of product a rolling mill stand
provided with pressure means for varying the crown of a work roll comprising
measuring the separation between work roll necks, converting that measure-
ment.to a gauge signal, determining ~he inclination o a work roll axis ~o the
horizontal, converting that determination to a crown signal, positioning in
the bite of the work rolls transducer means adapted to convert th~ width
of gap into a signal, applying crowning pressure to the work rolls correspond-
ing to a crowning pressure ~i~nal comprlsing the algebraic sum of the crown
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signal and the signal from a centrally loca~ed transducer~ and applying
rolling pressure to the work rolls correspon~ing to a rolling pressure
signal comprising the algebra.ic sum of the gauge signal and the signal from
a transducer adjaccnt a roll neck, and adju~ting those pressures until the
crowning pressure signal is e~ual to the rolling pressure signal.
Embodimcnts of the invenkion presently preferred are illus~rated in
the attached drawings, to which reference is now made.
Figure 1 is. a vertical cro~s-section of a portion of mill stand
perpendicular to the roll axis showing a f~rst cmbodiment of the apparatus
in place between the work rolls;
Figure 2 is a plan of the apparatus.shown in Figure l;
Figure 3 is.a cross-~ection of th~ apparatus taken on the plane
III-III of Figure l;
Figure 4 is a horizontal cro~s-sec~ion through a mill stand between
the work rolls!showing in plan a second embodiment of the apparatus in place;
Figure 5 is~ an elevation of the apparatus of Fi.gure 4;
Pigure 6 is an end elevation of the apparatus of Figures 4 and 5f
Figure 7 is.an enlarged cross-section through the apparatus of
Figure 4 taken on the~plane VII-VII ~hereof;
Figure 8 i~ a schematic arrangemen~ o the invention in a 4-high
mill s.tand interconnected with one embodiment o gauge and crown control
apparatus.; and
Figure 9 is a schematic arrangement of the .invention in a 4-high
mill stand interconnected with another embodimcnt of gauge and crown control
apparatus.
The firs.t embodiment of the apparatu~ shown in Figures 1, 2 and 3
compri`ses a rectangular frame 11 hàving
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parallel side pieces 12 and cross pieces 13 a~ each end of
~hose side pieces. Intermediate cross pieces 13 is a pair of
spaced-apart cross pieces 14 between whlch are positioned a
central transducer 15, transducers 17 at each end of cross
pieces 14 and transducers 16 intermediate the central transducer
15 and t~ansducer 17 on each slde. The leads from the various
transducers, which conveniently take the form of load cells,
are brought out in cable 19 at one end of frame 11. The height
of side pieces 12 and cross pieces 13 and 14 is slightly less
than the unloaded height of the load cells.
As may be seen in Figures 8 and 9, the apparatus also
comprises display means 24 having a central scale 25, scales 27,
one at each end, and scales 26 intermediate scales 25 and 27.
The positions of those scales correspond respectively to the
positions of load cells 15, 16 and 17 lengthwise of the rolls.
Central load cell 15 is connected to means 24 so as to actuate
a pointer which moves vertically on scale 25, through conductors
29, 153, 157 and crown calibrate conditioner 32. End load cells
17 are connected to scales 27 respectively through conductors
31, 155, 160 and gauge calibrate conditioners 33. Intermediate
load cells 16 are connected to scales 26 through conductors 30.
Figures 8 and 9 show the electrical connections for one side
only of the mill stand and it will be understood that duplicate
circuits are provided for the other side of the mill stand.
In use, frame 11 is inserted between lower work roll
119 and upper work roll 118 of a mill stand 110, those rolls,
of course bein'g separated to allow frame 11 to en-ter. Frame 11
is rolled in on table rolls 22 on each side oE the mill stand.
Frame 11 is positioned so that its load cells lie in a ver-tical
plane through the axis of work rolls 118 and 119, and the rolls
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of the mill stand are then brought together against the load
cells.
For any given rolling force corresponding to a given
gauge of ~inished product, the stand can be adjusted to sub-
stantial flatnes~ by regulating the crowning force while the
apparatus 11 is in the bite of work rolls 11~ and 119 until the
pointers of scales 25, 26 and 27 are brought to substantially
the same position. In the embodiment of the display device 24
illustrated, the scales 25, 26 and 27 are vertical and their
pointers extend horizontally across them so that when the
pointers are brought to the same position they form a horizontal
line across the scales. The sources o~ rolling ~orce are then
calibrated as are the sources o~ crowning force, so that after
the apparatus 11 has been removed from the rolls, the stand can
be set up to roll flat material of the desired gauge.
In Figure 8 the apparatus is shown interconnected with
gauge and crown control apparatus. A mill stand suitable for
the invention comprises an operator's side housing 110 and a
drive side housing 111 tied together at top and bottom in con-
ventional fashion. Each housing is formed with a conventionalwindow, within which windows are positioned upper backup rolls
chocks 112, lower backup roll chocks 113, and, between them,
upper work roll chocks 114 and lower work roll chocks 115.
Upper backup roll 116 is journalled in chocks 112, lower backup
roll 117 is journalled in chocks 113, upper work roll 118 is
journalled in chocks 114 and lower work roll 119 is journalled
in chocks 115. ~ hydraulic cylinder 108 with piston 109 is
positioned between the top of housing 110 and chock 112 and a
like cylinder and piston is positioned in the same way in hous-
ing 111. Chocks 113 rest on the bottom of housings 110 and 111.
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Between chocks 114 and 115 in housing 110 ls posi-
tioned a pair of hydraulic roll-bending cylinders 123, one on
each side of the roll neck. A like pair is positioned in the
same location in housing 111. Centrally located within each
cylinder 123, is a transducer 124. Work rolls 118 and 119 are
provided with elongated necks 125 and 126 respectively which
extend through the window in housing 110. Between the outer
ends of necks 125 and 126 is fixed a transducer 127. Transducers
124 and 127 are pre~erably mounted to act directly between the
upper and lower roll chocks and generate an electrical signal
corresponding to movement between the upper and lower roll
chocks.
Hydraulic fluid is supplied to pressure cylinders
108 through conduits 120 and 128 from servo valve~29. The
latter is furnished hydraulic fluid through conduit 130 from
pump 131 which is driven by motor 132~ Pump 131 pumps hydraulic
fluid from tank 107 and servo valve 129 discharges into thattank
through conduit 133. In like manner, roll bending cylinders 123
are supplied wi-th hydraulic fluid through conduits 121 and 135
from servo valve 136. That valve is furnished hydraulic fluid
through conduit 137 from pump 138 which is driven by motor 139.
Pump 138 pumps hydraulic fluid from tank 107 and ser~o valve
136 discharges into that tank through conduit 140.
The electrical output of transducer 127 is connected
by conductor 142 to the input of crown signal conditioner 143.
The output of conditioner 143 is connected by conductor 144 to
summing junction 145. The electrical output of transducers
124 is averaged and is then connected to gauge siynal conditioner
148 by conduc-tor 147. The output of conditioner 148 is connected
to summing junction 145 by conductor 149 and to summing junction
6.
151 by conductor 150. Conditioners 1~3 and 148 are conventional
and may include amplifiers, signal shapiny elements and the like.
Crown input command 152 is connected by conductor 153 to summing
junction 145. Gauge input command 154 is connected by conductor
155 to summing junction 151. Those commands furnish signals
which can be adjusted to correspond to the desired crown and
gauge respectively and incorporate read-outs of those values.
Summing junction 145 is connected by conductor 157 to the inputs
of gauge servo amplifier 158 and cxown servo amplifier 159.
Summing junction 151 is connected by conductor 160 to the input
of gauge servo amplifler 158. The output of that amplifier is
connected by conductor 161 to servo valve 129 and the output of
crown servo amplifier 159 is connected by conductor 162 to servo
valve 136.
We have specifically described above the connections
for the apparatus as applied to housing 110 on the operator's
side of the mill stand. That apparatus is duplicated on the
drive side of the mill stand, with -the exception of transducer
127, and is connected to control apparatus in the same way as
has been described for the operator's side of the mill stand.
A transducer identical to 127 would have to be located between
the drive spindles for the work rolls 118 and 119, which pre-
sents di~ficulties. We find that transducer 127 is adequate to
furnish signals to both sides as long as the work is reasonably
well centered in the rolls of the mill stand.
The operation of the apparatus of Figure 8 will now
be described without reference to the calibrating apparatus
shown in Figures 1-3. The following description assumes that
there is metal in the stand to be rolled.
Crown signal conditioner 1~3 and gauge signal
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conditioner 148 are adjusted so that their outputs a~e of
opposite polarity. The signals generated by transducer.s 127
and 124 and appearing on conductors ].44 and 149 respectively
are brought to summing junction 145 and are there compared
with the signal on conductor 153 from crown input command 152.
The bending of the work roll necks 125 and 126 toward each
other about the fulcrum at the roll midpoint caused by the
application of rolling pressure on those roll necks is counter-
balanced by bending the work rolls in the opposite direction
about the same fulcrum by bending cylinders 123. The amount of
this bending is i.nitially set by adjusting the crown input
command 152. Should the material entering the mill display
changes in hardness, flatness or gauye, an error signal will
appear on conductor 157. That error signal is applied both
to crown servo amplifier 159 and gauge servo amplifier 158, so
that working pressure cylinders 108 increase or decrease their
force by an incremental amount and bending cylinders 123
increase or decrease their force by the same incremental
amount but in the opposite direction. Thus, the sum of the
vertically acting forces on housings 110 and 111 remains
unchanged, and there is no change in the gauge of the work
being rolled. However, the bending moment exerted on work
rolls 118 and 119 is changed by the product of the change in
force of bending cylinders 124 multiplied by their lever arm,
the distance between the fulcrum and cylinders 123 or any
distance along the face of the backup roll toward the edges.
Therefore, the flatness of the work is preserved.
The gauge desired is initially set by adjustment of
gauge input command 154. The signal from transducer 124
through gauge signal conditioner 148 is summed with the
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reference signal from gauge inpu-t com~,and 154 in summing junc-
tion 151 and the error signal resulting is applied to gauge
servo amplifier 158. In response thereto, servo valve 129
adjusts the fluid pressure in pressure cylinder 108 so as to
change the roll gap and thus the signal generated by transducer
124 in the direction to bring the error signal to zero.
The appara~us, as has been mentioned, calibrates the
control apparatus above described. Callbrating apparatus 11 is
inserted ln the bite of rolls 118 and 119. The signal from
centrally located load cell 15 is passed through crown calibra-
tor conditioner 32 to summing junction 145, the output of whlch
on conductor 157 is displayed on scale 25 of display means 24,
as well as belng introduced lnto ampllflers 158 and 159. The
signals from outer load cells 17 are passed through calibrator
conditioners 33 to summing junctions 151, the outputs of which
on conductors 160 are displayed on scales 27 of display means
24, as well as being lntroduced into ampliflers 158. If the
outputs of load cells 17 are not equal, the servo ampliflers
158 on opposite side of the mill stand will adjust pressure
cylinders 108 to equalize those outputs and that equalization
will be made vlslble by display means 24. If the equallzed
outputs of cells 17 are different from the output of cell 15,
the signal from that latter cell will actuate servo ampliflers
158 and 159 and the pressure ln roll bendlng cylinders 123 will
be adjusted to bring those outputs to the same level.
Figure 9 hereln illustrates the calibrating apparatus
lnterconnected with another embodiment gauge and crown control
apparatus. The only differences between Figures 8 and 9 are
those between the two embodiments of the gauge and crown control
apparatus. In the embodiment shown in E'igure 8, the work roll
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crowning is effected by bending the work rolls by cyli~ders 123.
In the second embodiment shown in Figure 9, the work roll crown-
ing is effected by adjustable crown backup rolls 176 and 177.
The interconnection of the calibxation apparatus wlth the con-
trol apparatus is the same ~or both embodiments. It is not,
therefore, believed to be necessary to repeat the full descrip-
tion of the second embodiment of the gauge and crown control
apparatus nor the description of the interconnections with it
of the calibrating apparatus disclosed herein.
The second embodiment of the invention illustrated in
Figures 4-7 differs from the first embodiment above described
in being moved into position through window of the mill stand
rather than over the mill table. Mounted on housing 111, the
drive side housing, is a pair of arms 36, one on each side of
the housing. Those arms are affixed at opposite ends of a
shaft 37 which is journalled in brackets 38 affixed to housing
111, so that arms 36 pivot in brackets 38. Also affixed to
shaft 37 between brackets 38 is a pair of crank arms 39, the
outer ends of which are pivotally connected to the outer end
of a piston rod 40 of a hydraulic cylinder 41, the other end
of which is affixed to mill housing 111 so that cylinder 41
swings arms 36 toward and away from work rolls 118 and 119.
The free ends of arms 36 are pivotally connected to channel
members 44 which face the work rolls. In those channel
members 44 is fitted an elongaged member 45 so as to slide
therein parallel to the work rolls and inside the mill stand
window. Member 45 extends outside housing 111 on the drive
side, and is pivotally connected at its outer end to the piston
rod 61 of a hydraulic cylinder 62, the outer end of which is
pivotally connected to arm 36 on the outside of housing 111, so
that cylinder 62 slides member 45 from a position in which its
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inner end abuts the inside face of housing 111 to a position in
which its inner end approaches the inside ~ace of housing 110.
Member 45 carries one or more transducers. In
Figures 4 and 5 it ls shown carrying three such transducers 46,
47 and 48. Transducer 47 is positioned so as to be located at
the longitudinal center of the work rolls when member 45 is
fully extended between housings 110 and 111. Transducer 46 is
positioned to be located at the ends of the work rolls adjacent
housing 110 and transducer 4~ is positioned to be located at
the ends of the work rolls adjacent housing 111. However, as
will appear, we may also use one roll gap transducer only, and
position it at successive locations lengthwise of the wor]c
rolls by cylinder 62.
The structure of the roll gap transducer is shown in
Figure 7. A cylindrical housing 50 is fixed to member 45
extending toward the work rolls therefrom. In housing 50 and
extending therefrom toward the work rolls is a hollow cylinder
51 having an internal shoulder 52 intermediate its ends. A
linear transducer element 53 is fixed within cylinder 51 adja-
cent its base. The electric leads from transducer element 53are brought out through a cable 19 described in connection
with the first embod~nt of the invention. A plunger 54 fits
slideably within cylinder 51 extending beyond the open end
thereof and is urged outwardly by coil spring 55 which bears
against the inside of plunger 54 and shoulder 52. A rod 56
threaded into the inside end of plunger 54 passes through coil
spring 55 and abuts the movable element of transducer element
53. Plunger 54 is held in aJignment with housing 50 by a cap
57 which fits over the upper end of housing 50 but through
which plunger 54 passes. The outer end of plunger 5~ which is
tapered to a smaller diameter holds a spherical feeler kip 59.
Spherical support tips 60 are affixed to member 45 a~ove an~
below feeler tip 59, so as to make steadying contact with upper
and lower work rolls 118 and 119.
The embodiment of the calibrating apparatus above
described is normally withdrawn from the space between mill
housings 110 and 111 through the window in housing 111 by
hydraulic cylinder 62. Arms 36 are raised so as to withdraw
member 45 and its associated transducers from the gap of the
work rolls by cylinder 41. When the apparatus is to be used,
cylinder 62 is operated to move member 45 through the window in
mill housing 111 into the space between that housing and mill
housing 110. If member 45 carries three roll gap transducers
46, 47 and 48 as shown in Figures 4 and 5, member 45 is moved
to its extreme position in which transducer 47 is located at
the longitudinal center of the work rolls. Then cylinder 41 is
operated to move those transducers into the roll gap. Spring
55 holds plunger 54 in its outermost position and feeler tip 59
carried by it makes contact with the roll gap before support
tips 60 make contact with work rolls 118 and 119. Plunger 54 is
thus forced back against spring 55 until support tips 60 do make
contact. Movement of plunger 54 actuates transducer element 53
and produces a signal therefrom.
It is possible by the use of the second embodiment of
the invention above described to employ one transducer only and
move it lengthwise of the work rolls by sliding member 45 step-
wise, so as to sample the roll gap at any number of desired
locations. In such a case, a dispk~y devi.ce more sophisticated
than that described herein is desirably employed.
The apparatus of the second embodiment of -the
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invention above described may be i,nterconnected with the gauge
and crown control apparatus in the same way as has been des-
cribed herein with respect to the first embodimen-t of the
invention.
The apparatus of the first embodiment of the invention
is especially useful for calibrating reversing rolling mill
stands. In such mills that necessary clearances between chocks
and housing and elsewherè in the stand, which cannot be perfectly
symmetrical, result in optimum flatness crowning and rolling
pressures in one direction of rolling which differ slightly from
those for the other direction of rolling. In such reversing
stands, the apparatus is rolled in over a mill table in one
direction of rolling so as to position its transducers in the
bite of the work rolls and the rolling and crowning pressures
are adjusted for optimum flatness and gauge in the way herein-
before described. The zero settings for the respective pressure
applying means are noted or recorded. The apparatus is then
rolled through the gap, and brought back in the reverse direc-
tion of rolling so as to position its transducers in the bite
of the work rolls, and the adjusting procedure is repeated.
The zero settings of the respec-tive pressure applying means in
the reverse direction of rolling are also noted. Thus a
reversing mill stand can be rapidly set up for rolling a pro~
duct of optimum f],atness and gauge in either direction.
In the foregoing specification we have described
presently preferred embodiments of the invention; however, it
will be understood that the invention can be otherwise embodied
within the scope of the following claims.
