Rolling mill stand, especially for rolling strip

The rolling mill or roll stand which makes a rolled product, particularly a rolled strip or strip, comprises a pair of working rolls, which if necessary are supported on a pair of supporting rolls or on a pair of the supporting rolls and intermediate rolls, and in which the working rolls and/or the supporting rolls and/or the intermediate rolls are axially slidable relative to each other. Each of the rolls of at least one of the pairs of rolls is provided with a curved contour extending to the roll body ends. These curved contours, sometimes on opposite sides, extend over only a portion of the rolled product width. The curved contour extends over the entire roll body length of each roll and has a shape such that both roll body contours entirely compliment themselves in a certain relative axial position. The working or intermediate rolls have the curve contours tapered to one of the roll body ends and widened toward the other of the roll body ends and are arranged slidable in opposite axial directions so that each of the tapered ends of the working rolls or intermediate rolls between a rolled product edge and the associated end of a supporting roll advantageously is held and aligned with each edge of the rolled product.

FIELD OF THE INVENTION 
Our present invention relates to a rolling-mill stand for making a rolled 
product, especially a comparatively flat rolled product such as rolled 
strip. 
BACKGROUND OF THE INVENTION 
A rolling-mill stand which makes a rolled product, particularly rolled 
strip, can comprise a pair of working rolls, which if necessary are braced 
by a pair of supporting rolls or by a pair of supporting rolls and a pair 
of intermediate rolls. 
In this rolling-mill stand the working rolls and/or supporting rolls and/or 
intermediate rolls can be axially shiftable relative to one another and 
each roll of at least one of these pairs of rolls is provided with a 
curved contour extending to the roll body ends. 
These curved contours are provided for both rolls of that roll pair, over a 
portion of the rolled product width. The curved contour extends over the 
entire roll body length of each roll and both roll bodies have a shape in 
which both roll body contours entirely complement each other in a certain 
relative axial position. 
A rolling-mill stand of this type is described in European Patent 0 049 
798. The roll gap shape is influenced by the features disclosed therein. A 
special position for the rolls in regard to the rolled product edges is 
not disclosed. 
The working rolls are braced as usual over their length on intermediate or 
supporting rolls so that the roll force or load exerted by the supporting 
rolls is transferred over the entire length of the roll body. This has the 
result that the ends of the working rolls protruding laterally over the 
rolled product and thus not participating in the rolling process are bent 
by the roll forces exerted on them in the direction of the rolled product. 
Furthermore in roll stands with stiff working rolls this damaging bending 
of the working rolls during rolling of a centrally rolled section or 
product causes a weakened rolling of the center portion of the rolled 
product and an excessively strong rolling of the edges of the rolled 
product. This effect is particularly noticeable in operation with varying 
rolling conditions such as sheet or strip temperature and varying roll 
forces as well as on rolling of different width products. 
To eliminate this disadvantageous effect as set forth in German Patent 22 
06 912 in six-high rolling-mill stands, the intermediate rolls are 
adjustable to fit the rolled product width so that one end of the 
effective roll body of the upper intermediate roll is placed in the 
vicinity of one rolled product edge while the opposing end of the 
effective roll body of the lower intermediate roll is placed in the 
vicinity of the other rolled product edge. Thus each working roll contains 
an end portion free from pressure due to the associated intermediate roll. 
Furthermore in these rolling-mill stands, roll bending devices engage on 
the ends of the working rolls. The rolls are provided in the conventional 
way as symmetrically shaped and roll bending devices are provided. An end 
portion of the intermediate rolls is tapered conically in a comparatively 
short region with the disadvantage of a stepped change of the load 
distribution in the vicinity of the change in the angle of taper. 
A more serious disadvantage of this known roll arrangement is that the 
effect of conical tapering and the axial adjustment of the intermediate 
rolls is limited except on the roll strip edges and the center region of 
the strip can in no way be influenced by it. 
In German Patent 22 60 256 a roll stand with devices for axially shifting 
the working rolls in opposite directions on changing the rolled product 
width is disclosed so that one end of the working surfaces of a working 
roll is held between a rolled product edge and the end of the associated 
supporting roll. 
Moreover intermediate rolls are also provided so that the upper 
intermediate roll is shiftable in the same direction as the lower working 
roll and the lower intermediate roll is shiftable in the same direction as 
the upper working roll. Also a conical tapering of only the ends of the 
intermediate rolls is provided with the above described disadvantageous 
effects. 
OBJECT OF THE INVENTION 
It is an object of our invention to provide an improved rolling-mill stand, 
especially an improved rolling-mill stand used to make a rolled strip, 
which obviates the foregoing drawbacks. 
It is also an object of our invention to provide an improved rolling-mill 
stand, especially an improved rolling-mill stand which makes a rolled 
strip, in which the disadvantageous bending of the working rolls under 
roll forces is compensated for all rolled product widths employed. 
It is another object of our invention to provide an improved strip 
rolling-mill stand in which the roll bending effect of the roll bending 
devices is augmented without need for interruption of the rolling 
operation. 
It is a further object of our invention to provide an improved strip 
rolling-mill stand in which the required roll shifting motion is reduced. 
SUMMARY OF THE INVENTION 
These objects and others which will become more readily apparent 
hereinafter are attained, in accordance with our invention, in a 
rolling-mill stand which makes a rolled product particularly rolled strip, 
comprising a pair of working rolls, which if necessary are braced on a 
pair of supporting rolls or on a pair of supporting rolls and intermediate 
rolls, and in which the working rolls and/or supporting rolls and/or 
intermediate rolls are axially shiftable relative to each other and each 
roll of at least one of these pairs of rolls is provided with a curved 
contour extending from one roll body end to the other. 
These curved contours extend, at least in part, beyond edges of the rolled 
product. The curved contour extends over the entire roll body length of 
each roll and has a shape such that both roll body contours are entirely 
complementary in a certain relative axial position. 
By the contours of adjacent rolls or the same roll being complementary, we 
mean that when these ends or end portions are put together side by side 
they fit together exactly so that their longitudinal axes are 
substantially parallel. 
According to a feature of our invention the working rolls have curved 
contours tapered to one of the roll body ends and diverging to the other 
one of the roll body ends and are shiftable in opposite axial directions 
so that the tapered one of the ends of the working rolls is held between a 
rolled product edge and an end of an associated one of the supporting 
rolls. 
Alternatively in another embodiment of our invention the working rolls can 
have cylindrical or symmetrical roll bodies and the intermediate rolls 
have curved contours tapered to one roll body end and diverging toward the 
other roll body end and are shiftable in opposite axial directions in such 
a way that the tapered end of one of the intermediate rolls is held 
between one of the rolled product edges and one end of an associated one 
of the supporting rolls. 
Advantageously the bulged portions of both working or intermediate rolls 
cooperate in such a way that the tapered or constricted segments of the 
bulged contours are positioned in the vicinity of both roll product edges. 
There are a variety of possible forms of our invention for the first case 
in which the working rolls are contoured and their edges are aligned with 
the rolled product. In one example the working rolls have a curved contour 
comprising an approximately concave portion and an approximately convex 
portion with regard to the axial direction. 
It has proved particularly suitable when an end of a working roll is held 
aligned with a rolled product edge, i.e. lies in a common vertical plane 
therewith. 
Advantageously according to our invention also the intermediate rolls can 
be provided with a curved contour in the same way and can be axially 
shiftable in opposite directions like the working rolls so that one end of 
an intermediate roll is held in the vicinity of a rolled product edge. 
Further the working and intermediate rolls working together can also be 
aligned on opposite rolled product edges, although alternatively they can 
be aligned on the same rolled product edge. 
According to the second major alternative form of our invention the working 
rolls are cylindrical or symmetrical, the intermediate rolls are contoured 
and the tapered end of an intermediate roll is held between a rolled 
product edge and the end of the associated supporting roll. Using an S 
shape cross section for the intermediate rolls instead of the cylindrical 
shape allows the required sliding motion to be reduced up to about 60% 
with the same effect for the same strap or sheet width and roll force. 
While with cylindrical intermediate rolls the pressing force between the 
supporting rolls and the intermediate rolls and/or the intermediate rolls 
and the working rolls climbs to a value which according to the strap or 
strip width reaches 1.3 to 1.4 times the specific roll force (linear 
load), in contrast with the S shape cross section intermediate rolls the 
pressing force can be reduced about 20%. Instead of load jumps from a 
maximum value to zero at the ends of the intermediate roll bodies one 
maintains a continuous load gradient, e.g. over a distance of about 400 
mm. 
The intermediate rolls like the working rolls in the examples above can 
comprise an approximately concave portion and an approximately convex 
portion in regard to their axial directions so that the end of an 
intermediate roll can be held aligned advantageously on a rolled product 
edge. In this axial position of the rolls the tapered portion of both 
intermediate rolls acts on each rolled product edge simultaneously whereby 
the load distribution is particularly satisfactory in the edge regions of 
the rolled product.

SPECIFIC DESCRIPTION 
As is apparent from FIG. 1 two working rolls 1, 2 positioned substantially 
vertically over each other and which directly roll a rolled product are 
held in a known way by not illustrated structural elements mounted in a 
roll stand. 
The working rolls 1,2 are braced by an upper and a lower supporting roll 4, 
5. 
Each of the working rolls 1, 2 is tapered at one end, i.e. the end 6 of the 
working roll 1 and the other end 7 of the other working roll 2 have a 
bulged shape tapered toward the end of the roll body while their opposing 
ends 8, 9 have a complementary shape. 
As a whole the cross section through the working rolls 1, 2 can be 
considered as being singly S-shaped. The working rolls 1, 2 have at one of 
their ends pins, on which couplings for connection to drive mechanisms 
(not shown) are provided. 
The bulged tapered ends 6, 7 of the working rolls 1, 2 are positioned in 
the vicinity of the edges 3e of the rolled strip 3s by axial shifting. In 
this configuration large roll pressures on the rolled product edges 3e of 
the rolled product 3 are avoided. 
When the rolled product width changes, a sufficiently constant cross 
section of the strip can be attained by merely shifting the working rolls 
in the axial direction by coupling each roll with the unillustrated 
shifting drive so that one of the tapered ends 6, 7 of these rolls 1, 2 is 
placed in the vicinity of one of the rolled product edges 3e. 
FIG. 2 shows two working rolls 10 and 11 positioned substantially directly 
one over the other which roll the rolled product 12 and in a known way are 
held in nonillustrated structural members mounted in a roll stand. 
The two intermediate rolls 13, 14 bracing both working rolls 10, 11 are so 
arranged that their axes are positioned substantially over and/or under 
the axes of the working rolls 
Further each of the intermediate rolls 13, 14 is tapered to one end, i.e. 
the end 20 of the intermediate roll 13 and the other end 21 of the other 
intermediate roll 14 have a bulged shape which is constricted in the 
direction of the end of the roll body while the opposing ends 22, 23 have 
a complementary shape. On their ends the intermediate rolls 13, 14 have 
pins on which couplings for connection to nonillustrated drive mechanism 
are mounted. 
Also in this arrangement for the intermediate rolls 13, 14 large roll 
pressures on the rolled product edges 12e are avoided. When similarly one 
of the ends of the working rolls 10, 11 is not braced by the supporting 
rolls also an effective bowing under load or bending of the working rolls 
10,11 can be effected as a result of action by nonillustrated roll bending 
devices. 
Compensation of small changes occurs by known bending devices which respond 
quickly because of their smaller construction and which do not act 
excessively on the bearing and roll pins. When the rolled product width 
changes a sufficiently constant cross section of the strip can be attained 
by shifting the intermediate rolls 13, 14 in the axial direction by the 
not illustrated coupled shifting drive so that the tapered ends 20, 21 of 
these rolls are positioned in the vicinity of one of the rolled product 
edges 12e. 
By hindering the bowing under load or bending of the working rolls 10, 11 
caused by the roll forces and expanding the effective length of the roll 
bending a rolled strip or rolled product of constant cross section results 
despite changes in the rolled product width. 
FIG. 3 shows (like FIG. 2) two working rolls 30, 31 positioned over each 
other however these working rolls 30, 31 are contoured. The intermediate 
rolls 33, 34 supporting both the working rolls 30, 31 are so arranged that 
their axes are over and/or under the axes of the working rolls 30, 31. The 
intermediate rolls 33, 34 are braced by an upper and lower supporting roll 
35, 36. Further each of the working and intermediate rolls 30, 31; 33, 34 
are tapered at one end whereby the ends 40, 41, 42, 43 have a bulged shage 
and are tapered toward the roll body ends while the opposing ends 44, 45, 
46, 47 are complementarily shaped. The working and intermediate rolls 30, 
31; 33, 34 have pins on one of their ends on which couplings for 
connection of an not illustrated drive mechanism are mounted. 
In the roll stand according to our invention sufficient further space 
remains about the working rolls so that the upper and lower press 
mechanism, stripper or wiper and cooling devices may be positioned 
sufficiently close to the working rolls. 
FIG. 4 shows an additional embodiment of our invention similar to the 
embodiment of FIG. 3. A six high rolling-mill stand with shiftable 
intermediate rolls 33', 34' and working rolls 30', 31' is shown. Both the 
working rolls 30', 31' and intermediate rolls 33',34' are contoured having 
approximately concave 44', 45', 46', 47' and convex portions 40', 41' and 
42', 43'. In this example however the working roll 30' or 31' and 
intermediate roll 33' or 34' working together, i.e. on the same side of 
the rolled product 32', are aligned on one and the same rolled product 
edge 32'e whereas in the example of FIG. 3 they are aligned on rolled 
product edges 32e on opposite sides of the rolled product. 
The features according to our invention are not limited to the embodiments 
shown in the drawing. Many varying curved contours of working and 
intermediate rolls and also supporting rolls are also possible within the 
scope of our invention.