This invention relates generally to rolling mills, and is concerned
in particular with an improved roll assembly of the "overhung" type, where ring
shaped work rolls are mounted on the ends of driven roll shafts.
In the typical overhung roll assembly, a ring shaped roll has a cylindrical
bore received on a tapered section of a driven roll supporting shaft. A tapered
sleeve is inserted in wedged engagement between the tapered roll shaft section
and the cylindrical roll bore. In some cases, the wedged engagement of the sleeve
serves as the primary means of transmitting torque from the roll shaft to the roll.
In other cases, the tapered sleeve mainly serves as a centering device, with torque
being transmitted from the roll shaft to the roll by other means, e.g. through
keys or other like mechanical interengagements, or by hydraulically loading adjacent
components of the roll assembly against the roll flanks to transmit torque by frictional
When the tapered sleeve serves as the primary torque transmitting
component, it exerts substantial radial force on the roll. The roll must therefore
be radially thickened in order to provide the strength required to withstand the
resulting increased hoop stress. The increased thickness of the roll is accommodated
by a reduction in the shaft diameter, which disadvantageously reduces shaft rigidity.
Axial loading of the tapered sleeves or other torque transmitting
components of conventional roll assemblies is typically achieved by specially designed
hydraulically actuated tools. Such tools are expensive and extremely heavy, usually
requiring maintenance personnel to employ lift cranes when engaging and disengaging
the tools from the roll assemblies. Non-productive mill downtime is thus prolonged
because most mill installations only have a limited number of lift cranes available
for use by maintenance personnel.
An objective of the present invention is to provide an overhung roll
assembly in which the tapered sleeve serves primarily as a centering device, with
torque being transmitted from the roll shaft to the roll by other components of
the roll assembly in frictional contact with the roll flanks. Roll hoop stresses
are thus advantageously reduced, making it possible to achieve a corresponding
reduction in roll thickness and a beneficial increase in shaft diameter.
A companion objective of the present invention is the provision of
a simple mechanically actuated arrangement for axially loading the torque transmitting
roll assembly components acting in frictional contact with the roll flanks. This
is accomplished through the use of low cost light weight tools which can be employed
by maintenance personnel without resort to auxiliary equipment such as overhead
In a preferred embodiment of the invention to be described hereinafter
in greater detail, the foregoing objectives and advantages are achieved by rotatably
fixing an axially shiftable circular retainer adjacent to both the outboard flank
of the ring shaped roll and the outboard end of the tapered sleeve, the latter
having been loosely inserted between the tapered section of the roll shaft and
the cylindrical bore of the work roll. A nut is then threaded onto the end of the
shaft. The nut acts against the circular retainer, which in turn abuts and urges
the tapered sleeve into a tightly inserted centering position between the tapered
shaft section and the cylindrical roll bore. Jackscrews threaded through the retainer
are then tightened against the outboard roll flank to clamp the inboard roll flank
against an adjacent abutment, which typically will comprise an enlarged diameter
circular shoulder on the roll shaft. The resulting frictional contact of the jackscrews
and shaft abutment with the opposed roll flanks serves as the primary torque transmitting
Preferably, the circular retainer is axially coupled to the tapered
sleeve by means of a bayonet connection or the like. Thus, removal of the nut followed
by continued tightening of the jackscrews will result in the tapered sleeve being
extracted from its tightly inserted centering position, thereby freeing the roll
for removal from the roll shaft.
These and other objectives, features and advantages of the present
invention will now be described in greater detail with reference to the accompanying
- Figure 1 is a longitudinal sectional view taken through a roll assembly in
accordance with the present invention;
- Figure 2 is a end view of the roll assembly looking from right to left in Figure
- Figure 3 is a partial cross section view taken along line 3-3 in Figure 1;
- Figure 4 is an exploded view of the roll assembly; and
- Figure 5 is a view similar to Figure 1 showing the components of the roll assembly
in a sleeve extraction mode.
Referring now to the drawings, a roll shaft 10 has a tapered section
10a leading from an abutment in the form of a circular shoulder 10b to reduced
diameter end section 10c having a threaded end 10d. A ring shaped roll 12 has inboard
and outboard flanks, 12a, 12b and a cylindrical bore 12c. The roll 12 is axially
mounted on the shaft 10, with its inboard flanks 12a seated against the abutment
shoulder 10b and with its cylindrical bore 12c surrounding the tapered shaft section
The shaft 10 is journalled for rotation in a housing 11 by bearings,
one of which is depicted at 13. A seal assembly "S" serves to retain lubricant
in the housing while excluding externally applied cooling water.
A tapered sleeve 14 is interposed between the tapered shaft section
10a and the cylindrical bore 12c of the roll 12. The outboard end of the sleeve
includes a collar with a circular groove 14a located inwardly of circumferentially
spaced radially outwardly protruding lugs 14b.
A circular roll retainer 16 is axially received on the shaft end section
10c. The retainer is axially shiftable, but is rotatably fixed with respect to
the shaft 10 by any convenient means, for example by inwardly protruding keys 16a
received in keyways 10e in the shaft section 10c. The retainer 16 is internally
grooved as at 16b adjacent to circumferentially spaced inwardly protruding lugs
16c. As can best be seen in Figure 3, the lugs 16c are configured and arranged
to coact in a bayonet type mechanical interengagement with the lugs 14b of the
sleeve 14 to axially couple the retainer to the sleeve.
A nut 18 is threaded onto the threaded end section 10d of the shaft.
The nut is operative via the retainer 16 to tightly insert the sleeve 14 between
the tapered shaft section 10a and the cylindrical roll bore 12c, thereby centering
the roll 12 on the shaft 10. With the nut thus tightened, the outboard roll flank
12b and the adjacent inboard face of the retainer 16 will either be in face-to-face
contact, or there may be a slight clearance therebetween as indicated at 20 in
Jackscrews 22 are threaded through the retainer 16 into axial engagement
with the outboard flank 12b of the roll1 12. As the jackscrews are tightened, the
inboard flank 12a of the roll is urged against the shaft abutment shoulder 10b,
and the retainer 16 is confined against movement in the opposite direction by the
The opposed axial forces exerted on the roll flanks 12a, 12b by the
abutment shoulder 10b and the jackscrews 22 generate the frictional forces required
to transmit torque from the roll shaft 10 via the retainer 16 to the roll 12.
As can best be seen by reference to Figure 5, roll removal is easily
accomplished by first removing the nut 18 and then continuing to tighten the jackscrews
22. This will force the retainer 16 away from the outboard roll flank 12b, with
an accompanying extraction of the tapered sleeve 14 as a result of the mechanical
interengagement ofthe retainer lugs 16c with the sleeve lugs 14b.
In the light of the foregoing, it will now be appreciated by those
skilled in the art that the present invention offers a number of significant advantages
over conventional roll mounting assemblies. For example, the role of the tapered
sleeve 14 is restricted primarily to centering the roll 12 on the tapered shaft
section 10a. As a result, the roll is subjected to only moderate hoop stresses.
The designer can thus reduce roll thickness, with a corresponding beneficial increase
in shaft diameter. The lower hoop stresses also result in the rolls 12 and the
sleeves 14 having longer useful lives.
The sleeve 14 is seated in its operative position simply by tightening
nut 18. This can be accomplished by mill personnel using standard light weight
relatively inexpensive air wrenches.
Torque is transmitted primarily by the exertion of opposed axially
generated frictional forces on the roll flanks. These forces are developed simply
by tightening the jackscrews 22, which again can be accomplished with standard
air wrenches. The same tools can be employed to extract the tapered sleeve 14 during
Various changes and modifications may be made to the embodiment herein
chosen for purposes of disclosure. By way of example only and without limitation,
the retainer 16 may be rotatably fixed to the shaft 10 by other known and functionally
equivalent arrangements, such as machining coacting flat surfaces on the shaft
section 10c and the interior bore of the retainer. Spacer rings or the like may
be interposed between any of the axially arranged components, e.g. between the
shoulder 10b and inboard roll flank 12a, between the outboard roll flank 12b and
the retainer 16, etc.
It is the intention to cover these and any other mechanically and
functionally equivalent changes and modifications which do not depart from the
overall concept of the present invention as defined by the claims appended hereto.