Rolling mill method

A metal workpiece such as a slab is rolled into a desired width without requiring broadsiding. The system generally involves reducing a first portion along the width of the workpiece to a first thickness while creating a second portion along the width of the workpiece having a thickness greater than the first portion thickness and having a predetermined mass. Subsequently the second portion is reduced to establish a predetermined increase in the width of the workpiece and a decrease in the thickness of the workpiece to obtain a substantially uniform thickness along substantially the entire width of the workpiece. A preferred approach includes providing a pair of cooperating work rolls at least one of which has a generally cylindrical portion and at least one adjacent tapered portion. Initial reduction is effected by employing a pair of cooperating cylindrical central portions and at least one tapered portion. This provides a workpiece with a reduced portion and an enlarged portion. The workpiece subsequently may be rotated 180 degrees or side shifted and rolled between a generally cylindrical central portion and a second pair of tapered portions. Subsequently, further reduction may be effected solely between a pair of central portions. Relative axial movement of one work roll with respect to another may be employed in effecting sequential spreading of the workpiece.

BACKGROUND OF THE INVENTION 
1. Field Of The Invention 
The present invention relates to a method and apparatus for rolling a metal 
workpiece by means of work rolls having a cylindrical portion and a 
tapered portion. 
2. Description of The Prior Art 
It has been known to provide a workpiece of given width by longitudinal 
slitting of the edges. This, however, can produce substantial scrap. 
It has also been known in connection with the rolling of metal slabs to 
provide an initial profile from the sizing pass wherein the central 
portion of the slab is of reduced thickness with respect to the generally 
transversely outwardly diverging lateral portions thereof. Subsequently, 
the workpiece is rotated 90 degrees and is run through a rolling mill 
stand which provides a generally uniform thickness to the workpiece. The 
workpiece is subsequently rotated 90 degrees in the opposite direction 
from the initial rotation and further rolling is effected so as to provide 
a workpiece of desired uniform thickness. This practice is known as 
"broadsiding". See generally U.S. Pat. Nos. 4,238,946 and 4,392,371. One 
of the difficulties with this practice is the need to effect two 90 degree 
rotations of the workpiece. 
U.S. Pat. No. 3,857,268 discloses axially shiftable tapered work rolls 
employed to accommodate varying workpiece width and improve flatness 
control; See also Japan No. 59-110401 and Japan No. 58-53384. These 
approaches do not employ the method for spreading the workpiece. 
In spite of these known practices, there remains a need for a more 
efficient, more direct method and associated apparatus for effecting 
rolling of a plate of a desired thickness. 
SUMMARY OF THE PRESENT INVENTION 
The present invention has met the above-described need by providing in one 
embodiment a method of rolling metal wherein a rolling mill has a pair of 
cooperating work rolls having a generally cylindrical central portion and 
at least one adjacent tapered portion. An initial reduction of the 
workpiece is effected between a pair of cylindrical portions and a first 
pair of tapered portions. A second reduction is effected between a pair of 
cylindrical portions and a second pair of tapered portion disposed on the 
other side of the cylindrical portions. Intermediate reductions may be 
effected, if desired. Subsequently, a further reduction is effected solely 
on a pair of said cylindrical portions. In general, these reductions will 
be effected on separate roll stands as by sequentially in a tandem mill, 
for example. 
It is an object of the present invention to provide an efficient means of 
rolling a metal slab to the desired uniform thickness and width without 
requiring the use of broadsiding. 
It is a further object of the present invention to provide such a method 
and apparatus which employ tapered roll work surfaces to alternately 
cooperate with cylindrical central work surface portions in effecting 
intermediate stages of rolling a slab into a transfer bar of desired 
thickness. 
It is a further object of the present invention to provide an economical 
and efficient means for converting a slab into a metal plate of desired 
thickness. 
It is a further object of this invention to provide a workpiece of desired 
width and thickness without requiring edge slitting or broadsiding. 
These and other objects of the present invention will be more fully 
understood from the following description of the invention on reference to 
the illustrations appended hereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now more specifically to FIG. 1, there is shown a pair of work 
rolls 2, 4 and a pair of associated cooperating backup rolls 6, 8. Work 
roll 2 has a generally centrally disposed, generally cylindrical portion 
in surface-to-surface contact with a corresponding portion of backup roll 
6. Disposed adjacent to and laterally of the central portion 10 are a pair 
of tapered portions 12, 14 which extend toward the respective roll necks 
16, 18 and converge inwardly toward the respective ends of roll 2. 
Similarly, roll 4 has a generally centrally disposed generally cylindrical 
portion 22, a pair of adjacent tapered portions 24, 26 which extend 
generally in the direction of the roll necks 28, 30 and converge inwardly 
toward the respective ends of roll 4. It will be appreciated that tapered 
portions 14, 26 provide a first cooperative pair of roll end sections and 
tapered portions 12, 24 provide a second cooperative pair of roll end 
sections disposed on the opposite side of said central portions 10, 22 
from said first cooperative pair of roll end sections. Cylindrical portion 
22 is in surface-to-surface contact with backup roll 8. Workpiece 40 which 
may be assumed to have had an initial with W.sub.0 has been enlarged in 
width to a width W.sub.1 and has a generally rectangular portion and an 
adjacent tapered portion. 
Referring to FIG. 2, there is shown a second pass in which like numbers 
have been employed for like parts as compared with FIG. 1. The workpiece 
40 has been either rotated 180 degrees or side shifted such that the side 
of the workpiece near its opposite edge is in contact with tapered 
portions 12, 24, rather than tapered portions 14, 26 as was the case in 
connection with the initial reduction shown in FIG. 1. The roll gap in 
FIG. 2 is reduced with respect to that of FIG. 1 and a second reduction 
has been effected in the workpiece which is indicated as beeing 40' having 
a width W.sub.2 which is greater than width W.sub.1. 
FIG. 3 shows the final pass wherein the reduction is preferably effected 
solely between cylindrical work surfaces 10, 22 and the workpiece 40" has 
a generally rectangular configuration. It will be appreciated, that in 
this manner, the slab which had an initial width W.sub.0 has been widened 
to the desired width W.sub.E and has been reduced to the desired uniform 
thickness. All of this has been accomplished while taking advantage of the 
benefit of employing tapered lateral edges during the rolling process 
without requiring burdensome broadsiding of the workpiece. 
Referring to FIGS. 4 through 7 an additional feature of the present 
invention will be considered. FIG. 4 shows a metal slab having an initial 
thickness H.sub.o and an initial width W.sub.o. In this embodiment of the 
invention it is contemplated that there will be relative axial shifting of 
the rolls so that the cylindrical portions will not be aligned. The rolls 
may be generally of the type illustrated in FIGS. 1 through 3 wherein a 
cylindrical portion on each roll has at least one portion adjacent thereto 
which tapers generally toward the roll end and will preferably have two 
such adjacent tapered portions. 
In FIG. 5 there is shown a roll 50 having a cylindrical portion 52, an 
adjacent tapered portion 54 and a roll neck 56. A similar tapered portion 
and roll neck (not shown) may be provided at the other end of the roll. 
Similarly, roll 60 has a cylindrical portion 62, a tapered portion 64 and 
a roll neck 66. This roll 60 may also have a second tapered portion and 
roll neck (not shown). It will be appreciated that both of the rolls have 
been set in relative position through axial movement of one or both rolls 
such that the rolls are offset with respect to the center line of the mill 
stand. Roll 50 is offset to the right as viewed in FIG. 5 and roll 60 is 
offset to the left as viewed in FIG. 5. This results in a segment of the 
cylindrical surfaces 52, 62 working on workpiece 70, one edge portion of 
the workpiece 70 being rolled between cylindrical surface 62 and tapered 
surface 54 and the other edge portion of the workpiece 70 being rolled 
between cylindrical surface 52 and tapered surface 64. The workpiece 70, 
therefore, has generally outwardly tapered portions at both longitudinal 
edges and has a thickness adjacent to the cylindrical portion of the roll 
equal to H.sub.1 and a workpiece width W.sub.1. 
As is shown in FIG. 6, roll 50 has been shifted axially toward the left by 
a predetermined distance and roll 60 has been shifted to the right by a 
predetermined distance. The cylindrical portions have greater contact with 
the workpiece than in FIG. 5. The workpiece 70' has a mean height or 
thickness H.sub.2 which is less than H.sub.1 and a width W.sub.2 which is 
greater than width W.sub.1. 
FIG. 7 shows the effect of continued relative axial shifting of the rolls 
with roll 50 having been moved farther to the left and roll 60 having been 
moved farther to the right. In this further rolling the thickness or 
height H.sub.3 is less than H.sub.2 and width W.sub.3 is greater than 
width W.sub.2. It will be appreciated tha the entire workpiece 70" is 
being rolled between cylindrical surfaces 52, 62. 
It will be appreciated that the method and apparatus of FIGS. 1 through 7 
may be employed in a single stand reversing mill or in a multistand mill. 
It will further be appreciated than in the method and apparatus of FIGS. 4 
through 7, the edges of the workpiece rather than being rolled between a 
pair of aligned tapered portions are in the initial and second reduction 
stages being rolled between one tapered roll surface and a cylindrical 
roll surface. 
Referring now in greater details to FIGS. 8 through 10, a further 
embodiment of the invention will be considered. In this embodiment, each 
of the rolls 80, 90, respectively, has cylindrical sections 82, 92, 
converging tapered portions 86, 94 and diverging tapered portion 84, 96. 
Roll 80 has roll necks 88, 89 disposed axially outwardly of the tapered 
portions 84, 86, respectively, and roll 90 has roll necks 98, 99 disposed 
axially outwardly of the tapered portions 94, 96. It is noted that rolls 
80, 90 are positioned relative to each other such that outwardly 
converging tapered portion 86 is disposed at the same end as outwardly 
diverging tapered portion 96 and outwardly diverging tapered portion 84 is 
disposed at the same end as outwardly converging tapered portion 94. 
Workpiece 100 as shown in FIG. 8 is being rolled between cylindrical 
surfaces 82, 92 with one edge being rolled between tapered surface 86 and 
cylindrical surface 92 and the other edge being rolled between tapered 
surface 94 and cylindrical surface 82. The workpiece 100 has both 
longitudinal edges enlarged with respect to the center portion. 
In the position shown in FIG. 9, roll 80 has been shifted to the left 
axially and roll 92 has been shifted to the right axially. As a result, 
workpiece 100' is being rolled between cylindrical surfaces 82, 92 and one 
edge is being rolled between tapered portion 96 and cylindrical portion 82 
while the other edge is being rolled between tapered portion 84 and 
cylindrical surface 92. In this manner, workpiece 100' is provided with 
outwardly converging longitudinal edges. 
Referring to FIG. 10, there is shown a plan view of a slab which is being 
rolled in a reversing mill in the direction shown by arrow C. The slab 110 
has longitudinal edges 112, 116 and transverse edges 114, 118. When the 
workpiece 100 is in contact with the outwardly converging tapered portions 
86, 94 and the associated rolls cylindrical surfaces 82, 92 the slab 
length near the longitudinal edges 112, 116 will tend to be shorter and 
assume the contour indicated by the letter A. When the workpiece is in 
contact with the outwardly diverging tapered portions 84, 96 and the 
associated cylindrical portions 82, 92, the slab length near the 
longitudinal edges 112, 116 will tend to be elongated and assume the 
contour shown by letter B. By balancing these two concepts, the desired 
slab shape is achieved without requiring broadsiding and while minimizing 
undesired scrap loss. A square edged plate may be created in this manner 
without shearing of the ends. 
Referring to FIG. 11, there is shown a further embodiment of the invention 
wherein a cylindrical roll 120 cooperates with a roll 130. The cylindrical 
roll 120 has a cylindrical surface 122 and a pair of roll necks 124, 126. 
The other roll 130 has a central cylindrical section 132, a first adjacent 
outwardly converging tapered section 134, a cylindrical portion 136 and a 
roll neck 138. Roll 130 also has a second outwardly converging tapered 
section 140 disposed adjacent to cylindrical section 132, and a 
cylindrical surface 142 and a roll neck 144. A pair of backup rolls 150, 
151 are shown in operative surface-to-surface contact, respectively, with 
respect to cylindrical sections 132, 136, 142 and 122 of the rolls 130, 
120. Workpiece 152 is being rolled with one portion being disposed between 
cylindrical surfaces 122 and 132 and one edge which diverges generally 
upwardly being rolled between cylindrical surface 122 and tapered surface 
134. 
FIG. 12 shows rolls similar to those of FIG. 11 but shows roll 130 being 
relatively moved with respect to roll 120 so as to provide workpiece 152' 
with a contour substantially identical to workpiece 152 of FIG. 11, both 
of which have a width W.sub.1. 
FIGS. 13 through 15 illustrate a reversing mill employing the concept of 
FIGS. 11 and 12 wherein relative side shifting either of the workpiece or 
of the two work rolls is provided. As is shown in FIG. 13, the initial 
workpiece 170 has a width W.sub.0 and is being rolled adjacent to a first 
end of roll 130 (with the other rolls not being shown). The workpiece 172 
has been spread to a width W.sub.1 and has a reduced thickness with 
respect to workpiece 170. 
Referring to FIG. 14, the mill is reversed and the workpiece rolled 
adjacent to the second end of roll 130. The workpiece moving in the 
direction indicated is subjected to a spreading from a width W.sub.1 to a 
greater width W.sub.2. With or without intermediate rolling stages, the 
further and final rolling stage shows the workpiece moving from right to 
left in FIG. 15 and going from a width W.sub.E-1 to a width W.sub.E. It 
will be appreciated that in FIGS. 13 and 14 first one edge of the strip is 
being rolled both by the tapered and cylindrical surfaces and the 
cooperation between a first tapered surface and a cylindrical surface and 
then the other edge is rolled by the cooperating cylindrical surfaces and 
the other tapered surface cooperating with a cylindrical surface. In the 
final pass shown in FIG. 15, two cylindrical surfaces do the rolling. 
Referring to FIG. 16, there is shown a multistand mill wherein rolls having 
a central cylindrical portion and a pair of adjacent outwardly converging 
tapered portions act on the workpiece to provide initial rolling by one 
cylindrical portion and one tapered portion with a pair of cooperating 
cylindrical surfaces on one edge and then a second reduction stage 
employing the other tapered surface in cooperation with a cylindrical 
surface and a pair of cylindrical surfaces with the final reduction being 
effected solely between two cooperating cylindrical surfaces. In FIG. 16, 
initial reduction is effected by roll 190 on workpiece 196 having a width 
W.sub.0 with the emerging product 198 having a reduced thickness and 
increased with W.sub.1. The second reduction is effected by roll 192 which 
spreads or widens the workpiece 200 having an increased width W.sub.2 and 
a reduced thickness with respect to workpiece 198. With or without 
intermediate stages the final reduction is effected by roll 194 wherein 
cooperating cylindrical surfaces spread the workpiece 202 to a width 
W.sub.E and reduced thickness. 
In general, it is preferred that with respect to the tapered surfaces of 
the work rolls of the present invention the tangent of the angle of taper 
be greater than the coefficient of friction between the roll and the 
material. 
It will be appreciated that while the illustrations have in some instances 
shown work rolls of the invention used in two high mills and in four high 
mills, the invention is not so limited. 
It will be appreciated that in the broader aspects of the invention an 
initial reduction preferably involves reducing a first portion along the 
width of the workpiece to a first thickness while creating a second width 
portion having a thickness greater than said first portion thickness and 
having a predetermined mass. Thereafter, a subsequent workpiece reduction 
involves reducing said second portion to cause a predetermined increase in 
the width of the workpiece and a decrease in the thickness thereof to the 
extent of obtaining a substantially uniform thickness along substantially 
the entire width of said workpiece. 
It will be appreciated, therefore, that the method and apparatus of the 
present invention have provided an effective means for providing the 
desired reduction in a workpiece to achieve the predetermined thickness 
and width without requiring scrap creating edge slitting and also without 
requiring broadsiding. All of this is accomplished by sequential rolling 
at least some of which involves rolling of a portion of the workpiece in 
contact with a tapered work roll surface disposed adjacent to a 
cylindrical work surface. 
Whereas particular embodiments of the invention has been described above 
for purposes of illustration, it will be appreciated by those skilled in 
the art that numerous variations of the details may be made without 
departing from the invention as described in the appended claims.