Method and apparatus for treating work rolls in a rolling mill

A header for applying a low pressure, non-turbulent, coherent curtain wall of coolant of a substantial uniform extent and thickness transversely across the rolling surface of a work roll of a hot rolling mill or the like, which curtain wall in cross-section is in the form of the uniform concentric enveloping camber of a portion of a roll barrel. The placement of the applied wall of coolant is controlled so that the built-up heat in each succeeding work roll portion leaving contact either with the hot material being rolled or its associated back-up roll in a multi-high mill is substantially and uniformly removed, and optimized cooling thereof is achieved. An adjustable discharge slot which may be tapered to discharge the curtain wall across the length of the roll's camber in a manner to control cooling of the work roll from end to end, i.e. the cooling rate of the length of a roll would have a parabolic curve.

BACKGROUND OF THE INVENTION 
The present invention relates to the uniform application of a fluid for 
treatment of a roll in a rolling mill or the like, for example, hot or 
cold rolling of a strip and more particularly, to employing a header for 
controlling the placement of the coolant across a transverse portion of 
the roll used for rolling hot strip to rapidly, substantially, and 
uniformly remove the heat built-up from successive portions of the roll 
leaving contact either with the heated material being rolled and/or with 
an associated back-up roll in a multi-high mill. 
Presently, headers for applying coolant to the rolls are generally employed 
to prevent damage to the surface finish of a roll or to thermally control 
the crown of a roll of a rolling mill. Efficient cooling in the rolling 
system particularly with regard to the work rolls has several advantages, 
such as: greater thermal stability; increased life of the roll and wearing 
thereof, and other mill components; better shape control of the product 
being rolled; and the reducing of the rate and severity of the surface 
failure of the work roll which failure is due to thermal fatigue. 
Several types of headers are known in the art, such as those employing 
spray nozzles as disclosed in U.S. Pat. Nos. 3,994,151 and 4,247,047, or a 
series of discharge slots as disclosed in U.S. Pat. No. 2,811,059. The 
spray nozzles of the first two U.S. patents deliver high pressure, high 
volume coolant which then fans out overlapping with the streams of an 
adjacent nozzle. This overlapping condition results in a non-uniform 
cooling of the rolling surface and furthermore, the impingement of the 
sprays against the roll surface is so great that the coolant drops are 
caused to rebound before meaningful cooling can even occur. In some forms 
of this type, the sprays are moved further away from the roll surface in 
an attempt to alleviate the foregoing problems, but this creates a 
distance between the adjacent streams of the sprays which frequently 
happens in the first mentioned form due to the nozzles becoming clogged, 
and therefore, a section of the roll does not receive any coolant. 
U.S. Pat. No. 2,811,059 discloses employing a header having a subdivided 
slot for discharging coolant under high pressure against the surface of a 
work roll, the discharge apparatuses being arranged on the entry side of 
the rolling mill stand very closely located to the work rolls to attempt 
to cool a roll section prior to its contact with a workpiece. 
While employing a series of slots instead of circular opening nozzles, the 
slots are spaced apart and the fluid is understood to be under relatively 
high pressure so that not only is the coolant applied on the entry side of 
the roll, but the construction of the slots, the placement of the header, 
and the pressure of the fluid will not produce enveloping coverage of the 
fluid, uniform in extent and thickness over the entire surface of the roll 
at the most advantageous location to give optimized cooling. 
Other problems arise with these high pressure sprays or flows in that the 
violent rebounding of the coolant molecules causes the grease and oil in 
the bearings of the rolls to be washed away resulting in damage to the 
spindles of the rolls. 
Apparatuses for applying low pressure, nonturbulent, coherent curtain walls 
of fluid to a surface for cooling thereof have been disclosed in a patent 
application for cooling rod, bearing U.S. Ser. No. 529,822 filed Sept. 6, 
1983, and in U.S. Pat. No. 4,047,985 issuing on Sept. 13, 1977 for 
symmetrically cooling the top and bottom surfaces of a strip, both 
inventions being that of the present inventor, J. I. Greenberger. Also, 
such apparatuses for cooling strip have been disclosed in U.S. Pat. No. 
4,403,492 issuing on Sept. 13, 1983; in U.S. Pat. No. 4,210,288 issuing 
July 1, 1980; and in recently issued patent application bearing U.S. Ser. 
No. 367,350 filed Apr. 12, 1982, the inventor being J. C. Dobson and/or 
Thomas Hope in all three cases. These apparatuses are designed to adapt to 
the particular environment in which they are used and for a particular 
product to be cooled and cannot and would not successfully be utilized in 
the same manner as the present invention. 
SUMMARY OF THE PRESENT INVENTION 
It is, therefore, an object of the present invention to provide a method, 
apparatus and arrangement for optimizing the cooling effect of a coolant 
flow applied against a heated area of a roll surface of the work rolls by 
creating and applying at the most advantageous location an enveloping 
fluid of low pressure coolant uninterruptedly across the entire length of 
the roll, which will be uniform in its extent, and therefore resulting in 
an overall improvement to the entire rolling system, such as greater 
thermal stability, greater roll and bearing life, and better shape control 
of the rolled product. 
It is a further object of the present invention to provide a method and 
apparatus for delivering a non-turbulent, coherent curtain wall of coolant 
or other medium to a surface of a work roll or the like to uniformly cool 
or otherwise treat a transverse area of said surface. 
It is a still further object of the present invention to provide a method 
and apparatus for delivering a controlled, coherent curtain wall of 
coolant to a heated area of a work roll, being that area immediately 
leaving contact with the work piece or in a similar area with an 
associated back-up roll in a four high or other multi-high rolling mill, 
the control of the delivery of the coolant being such that the coolant 
molecules travel directly and uniformly onto and around the roll surface 
only, thereby eliminating rebounding and entrance into the roll bearings. 
Yet a still further object of the present invention is to provide a coolant 
discharge apparatus having an adjustable continuous slot which may have a 
maximum center spaced section and from its center section to each opposite 
end section, the spacing may gradually decrease into a taper to deliver to 
the roll surface a non-turbulent, low pressure coherent curtain wall of 
coolant having a corresponding tapering thickness pattern to the extent 
that this pattern translates into a parabolic cooling profile for the work 
roll. 
And a further object of the present invention is to provide a coolant 
header for discharging one or more coherent curtain wall flows of coolant, 
said header located on both the delivery and entry sides of the rolling 
stand which header is constructed such that the desired coherent curtain 
wall flow or flows will envelope a selected portion of the work roll 
regardless of its distance from the work roll.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
The present invention has particular application in, but is not restricted 
to, a four high rolling mill stand 8 for the rolling of hot steel strip as 
shown in FIG. 1. For top and bottom work rolls 10, 12 there is a 
corresponding top and bottom back-up roll 14, 16, respectively, the latter 
according to usual practice having a greater diameter than work rolls 10, 
12. Strip 13 travels from left to right into the stand 8 of FIG. 1 as 
indicated by the arrow, which stand in a hot strip rolling mill may be one 
of several tandem stands of the finishing train or a single stand of a 
plate mill. In FIG. 1, top and bottom work rolls 10, 12, respectfully, are 
motor driven to rotate about their horizontal axis in a direction 
indicated by the arrow on rolls 10, 12. 
The higher the rolling speeds, the more important it is for the roll 
coolant applied to the rolling surface of work rolls 10, 12 be of the 
proper character, properly located and providing sufficient and uniform 
coverage and quantity, including such as to remain on rolls 10, 12, long 
enough to sufficiently, efficiently, and uniformly cool the surfaces 
thereof. Such a system is illustrated in FIG. 1, where coolant headers 20 
and 22 on the upstream or entry side of stand 8(to the left in FIG. 1) and 
coolant headers 24, 26 on the downstream or delivery side of stand (to the 
right in FIG. 1) are designed to deliver to work rolls 10, 12, separate 
curtain walls of coolant indicated by dash-dot lines to work rolls 10, 12 
which walls are approximately equal to the rolling surfaces of the rolls. 
These walls of coolant are of a low pressure of approximately 10 psi, and 
the coolant molecules are non-turbulent and coherent in that a generally 
uniform cross-sectional wall of coolant impinges upon the work roll 
regardless of the distance and/or angle of coolant headers 20, 22, 24, and 
26 relative to the roll surface of work rolls 10, 12. 
During the rolling of hot strip 13 the contacting surface areas of work 
rolls 10, 12 which are the roll bite areas absorb a substantial amount of 
heat existing in the strip due to the roll's direct contact with strip 13. 
Work rolls 10, 12 are directly contacted by back-up rolls 14, 16. In still 
referring to FIG. 1, headers 20, 22 on the entry side of stand 8 are 
angled such as to deliver a coherent curtain wall flow against a surface 
of top and bottom work rolls 10, 12 immediately leaving contact with their 
respective back-up rolls 14, 16, and in a direction towards the direction 
of rotation of the work rolls. This application of coolant on the entry 
side intensifies the cooling action of the surface of work rolls 10, 12. 
For top work roll 10, this impingement of coolant flow is in a fourth 
quadrant and for the bottom roll 12, impingement is in the third quadrant, 
which quadrants are so designated with reference to a plane divided by the 
reference axes x-y in a Cartensian coordinate system and counting 
clockwise from the area in which both x-y coordinates are positive. The 
coolant flow tangentially contacts under a low pressure work rolls 10, 12 
in their above mentioned fourth and third quadrant, respectively. 
As strip 13 exits from between the roll bite, approximately a first 
quadrant of upper work roll 10 and a first quadrant of lower work roll 12 
are the regions containing the maximum amount of heat, since these areas 
have just left contact with strip 13. As shown in FIG. 1, coolant headers 
24 and 26 on the delivery side of stand 8 are positioned to deliver a 
coherent curtain wall tangentially along the length of work rolls 10, 12 
in their first quadrants, which quadrants were defined earlier and which 
quadrants of work rolls 10, 12 remain in the same reference plane, 
however, the actual area on the roll surface changes due to the rotation 
of the work rolls 10, 12. 
Upon the tangential impingement of the coherent curtain wall flow 
coextensive along the length of work rolls 10, 12, the coolant having a 
very high retention factor is caused to separate and flow in opposite 
directions in film-like form to create a cooling field substantially 
extensive and uniform in length, height, and thickness around an arc 
segment of each work roll 10, 12. For headers 24, 26 on the delivery side 
of the stand 8, this means that when the coolant separates, a uniform 
film-like flow moves downward along top work roll 10 and upward along 
bottom work roll 12 into the roll gap to immediately cool this critical 
area of work rolls 10, 12. Naturally, the opposing flow after softly 
contacting the rolls 10, 12, travels upwardly along top roll 10 towards 
the area contacting back-up roll 14, and downwardly along bottom roll 12 
towards the area contacting back-up roll 16. 
As for headers 20, 22 on the entry side, the coolant upon rolls 10, 12 
separates into two substantially uniform film-like flows, one towards the 
contacting area with their respective back-up rolls and the other flow 
towards the rolling area. The flow towards the contacting area of the 
back-up roll with the work roll causes a "Puddling Effect" or an amount of 
coolant to accumulant thereby intensifying the cooling action on the 
surface of work rolls 10, 12. 
As shown in FIG. 1, strip 13 travels between strip guides 28 and 30 lacated 
on both sides of stand 8. The positioning of these strip guides makes it 
difficult in many applications to mount coolant headers 20, 22, 24 and 26 
any closer to work rolls 10, 12 than as shown, but the design of coolant 
headers 20-26 is such that they are easily mounted to strip guides 28, 30 
through suitable fastening means (not shown) and because of this 
limitation the type and controlled flow pattern of the present invention 
is of great advantage. 
The design and construction of each header 20, 22, 24, and 26, is shown in 
FIGS. 2 and 3 where each header is generally a rectangular container 36 
having a chamber 38 for receiving coolant, coolant inlets 40, one of which 
is shown in FIG. 3 and outlet 42. Excess coolant is carried away through 
drains 43, one of which is shown in FIG. 3. 
Outlet 42 extends the length of header 20, 22, 24 and 26, where only a 
portion of its length is shown in FIG. 3, but it is to be understood that 
the other portion of each header 20, 22, 24, 26 is similar to that shown 
in FIG. 3. Mounted on the lower portion of container 36 adjacent to outlet 
42 is member 44 which runs parallel to and extends the length of container 
36. This is provided so that plate member 46 can be affixed by nut and 
bolt assembly 48 to container 36 at outlet opening 42 to form a continuous 
elongated slot 50 at outlet opening 42. Several elongated members 52 are 
arranged in abutting relationship to fit between leg section 53 (one of 
which is only shown) of plate member 46, which arrangement forms a 
continuous longitudinal edge 54. 
These members 52 are affixed to member 44 through several nut-bolt 
assemblies 56 extending through slots 58 and cooperates with longitudinal 
edge 60 of plate member 46 to form the continuous elongated slot 50. The 
contour of continuous longitudinal edge 54 of elongated members 52 is such 
that a tapering effect can be obtained from the middle section outwardly 
to opposing ends of slot 50 where the middle portion of slot 50 has a 
wider spacing than the opposed ends. This is particularly shown in FIG. 3, 
where the opposing ends are formed by the furthest portions 52 of slot 50, 
one portion 52 located to the right of FIG. 3, and which is to be 
understood, one portion 52 located to the left in FIG. 3 if coolant 
headers 20, 22, 24, 26 were extended to be fully represented in FIG. 3. 
Central member 52 can be positioned furthest away from longitudinal edge 
60 to give this widest spacing, and hence, maximum cooling, and naturally, 
the outer members 52 located on opposing sides of central member 52, can 
be positioned to give the narrowest spacing, and hence, a tapering cooling 
effect in which the outer ends can be controlled to give the minimum or no 
cooling effect. 
Adjustment of slot or opening 50 is done through movement of members 52 
towards or away from longitudinal edge 60, which movement is easily 
accomplished due to slots 58 in each member 52. This adjusting of the 
spacing of opening 50 does not interfere with the integrity of the 
coherent curtain wall flow, but only varies the transverse thickness of 
the flow. 
The location and positioning of each header 20, 22, 24, 26 is selected to 
be as close to the roll bite in the case of headers 24, 26 and to the area 
between the back-up roll and its respective work roll as in the case of 
headers 20, 22 as is feasible without interfering with any of the other 
apparatuses necessary for the rolling operation, such as strip deflector 
rolls, strip cooling means, etc. As shown, and as mentioned previously, 
headers 20, 22, 24, 26 are mounted to strip guides 28, 30. Regardless of 
the distance between the work rolls 10, 12 and headers 20-26, a flow of 
coherent coolant is continually discharged to quickly and efficiently 
remove a substantial amount of heat transmitted to the segment of work 
rolls successively leaving their contacting areas. This becomes important 
when it is realized that after many hours of production rolling, the outer 
surface of work rolls 10, 12 is worn down to where the surface has to be 
reground, resulting in a lesser diameter for each work roll 10, 12. This 
regrinding is done several times before the life of the roll is depleted, 
however, headers 20-26 can remain in their initial operating position 
without being adjusted to accommodate this varying distance between the 
work rolls and headers 20-26, and without deviating from the cooling 
efficiency of the roll surface obtained for the original diameter of work 
rolls 10, 12. During roll changing, strip guides 28, 30 are moved away 
from work rolls 10, 12 and a new pair of work rolls are inserted in the 
stand 8, and the guides brought back to their former positioning with 
headers 20-26 angled in a predetermined positioning suitable to direct the 
coolant flow against the surface of work rolls 10, 12. 
Referring again to tapered slot 50, this opening outline of slot is such 
that it is adjusted to accommodate the camber of a roll's barrel when the 
crown is thermally expanded in the rolling process. The present invention 
is being described in the environment of a hot mill. Work rolls 10, 12 
have a mechanical camber and the heat of the strip causes an increase in 
this camber resulting in thermal camber. Slot 50 is such that the flow of 
coolant is corrective to the extent the mechanical camber is maintained 
but the thermal camber is eliminated. This coolant flow pattern is 
imparted on the roll surface which among the many other characteristics of 
curtain wall flow contribute to obtain the optimum cooling thereof, which 
optimum cooling effect would be represented by a parabolic curve if 
cooling vs. roll length is plotted on a graph. 
In such a graph, the greatest cooling rate can be controlled to occur in 
the center of work rolls 10, 12 where the greatest amount of heat is 
absorbed, and would taper from the center to the opposite ends thereof. 
This parabolic cooling curve parallels the known distribution of 
temperature along the roll barrel, and therefore the great significance of 
the uniform and optimum cooling effect of the subject invention can be 
greatly envisioned. 
The transverse dimension of strip 13 dictates the extent of the heat 
pattern transmitted along the other surface of the barrel for work rolls 
10, 12, i.e. if the rolling mill is rolling a minimum width strip, than 
this minimum heat area is transferred to work rolls 10, 12 and 
correlatively, this holds true for the maximum width strip. 
Adjustable slot or opening 50 of headers 20, 22, 24, 26 are made to 
accomodate the varying width strip. Members 52 can be positioned to create 
a length slot corresponding to the width strip being rolled, which, in 
effect varies the flow rate along the length of slot 50. 
At all times the center opening may be spaced at its maximum operated 
positioning. As a minimum width strip is being rolled heat is transmitted 
to an area of the roll body equal to the width of the strip. In this case, 
the two outer members 52 of tapered slot 50 of headers 20-26 may be 
brought towards longitudinal edge 60 a distance such that only the 
required coolant flow rate is delivered through central member 52. If a 
maximum width strip is being rolled heat is transmitted to a greater area 
along the roll barrel. In this instance, the two outer members 52 can be 
positioned in their maximum spacing away from longitudinal edge 60 to 
permit an even distribution of the coolant flow rate along the entire 
length of slot 50. This positioning of members 52 to vary the flow rate 
along the slot's length translates into varying parabolic cooling curves, 
and as mentioned previously, closely simulates the desired parabolic 
cooling across the roll barrel. As already alluded to, low pressure 
coolant is delivered to headers 20-26 through inlets 40, into chamber 38, 
and through outlet 42. Any excess volume is drained through drain lines 
43. 
The coolant for rolling hot steel strip generally is water, but it is to be 
noted that other base liquids can be used for treatment of a roll, or the 
like, in other mills and in non-mill applications. Also, even though the 
subject invention is described in the environment of a four high rolling 
mill for rolling hot steel strip, the scope of the subject invention 
encompasses the rolling of ferrous and also non-ferrous metals such as 
aluminum and mechanical aplications where heat is to be removed from the 
apparatus for cold work thereof and where the invention can be utilized 
for applying rolling and cooling lubricants. 
Even though headers 20-26 are shown in the figures to have only one nozzle 
outlet for delivering curtain wall flow these headers 20-26 can also be 
designed with two or more elongated nozzles each delivering a curtain wall 
flow. Such flows can be regulated to deliver a desired percentage of the 
flow rate of coolant. 
From the foregoing, it can be appreciated that not only is optimum cooling 
of a section of a face of a work roll achieved, but in view of this 
optimize cooling of the entire rolling system including the components of 
stand 8 is achieved by the providing of headers 20, 22, 24, and 26 and 
their particular positioning relative to the critical areas of work rolls 
10, 12 in their rolling of strip 13. Due to the integrity of the coherent 
curtain wall flow, the entire face or outer peripheral surface of each 
work roll 10, 12 is uniformly cooled. Also, because the coolant flow is 
lowpressure, non-turbulent, and coherent its impingement upon the roll 
surface is controlled and restricted to flow only upon the roll instead of 
entering the bearings as is the case with high pressure flows. 
In accordance with the patent statutes I have explained the principals and 
operation of my invention and have illustrated and described what I 
consider to represent the best embodiment thereof.