This invention concerns a system to install the rolling rings on
a rolling roll, as set forth in the main claim.
To be more exact, the system according to the invention is used to
install the rolling rings, which generally but not only are made of cast iron,
on the relative supporting half-shafts.
The invention is applied in particular but not only to rolling mill
stands for single-channel roughing rolling with box passes or diamond passes.
In rolling mill stands of the state of the art and, in particular,
in universal rolling mill stands a procedure of keying the rolling rings to a pair
of half-shafts, which are coupled together and face each other substantially at
the centre line of the relative rolling ring, has been disclosed.
These half-shafts are generally kept under tension by pre-loaded
tie rods inserted coaxially into the half-shafts.
These pre-loaded tie rods ensure a union between the half-shafts
in each working step and also transmission of the torque.
The half-shafts include lateral flanges which cooperate by contact
with the lateral surfaces of the rolling rings.
The torque is transmitted by friction through these flanges to the
The systems disclosed in the state of the art for the coupling of
the half-shafts involve some drawbacks, especially as regards the deflections under
load which take place in general in all the rolling steps and which may be especially
damaging in the event of severe working conditions.
According to the installation system of the state of the art the
half-shafts are kept reciprocally under tension by pre-loaded tie rods, but no
type of reciprocal support is created between one half-shaft and the other half-shaft.
In particular, at the centre line of the rolling rings, where the
transverse deflection under load takes on the highest values, there is a zone of
coupling of the two half-shafts which coincides with the zone of less resistance
to stresses applied in a direction perpendicular to the axis of the half-shafts
Another drawback often encountered in installation systems of this
type concerns the rapid wear to which the parts of reciprocal cooperation of the
half-shafts are subjected, namely the relative inner ends.
This rapid wear involves frequent corrective work on important parts
of the half-shafts, long times for dismantling the elements to be maintained, the
use of a labour force and still other problems.
Moreover, in view of the considerable cost and effort required, this
corrective work often tends to be postponed, thereby entailing working conditions
which are not always the best.
Document WO-A-92/07668 shows a roller for a roll stand with an interchangeable
roller ring and a divided roller body, both parts of which form a clamping flange
and are interconnected by a central tension connector. An axial clamping device,
comprising both threaded elements and a hydraulic device, is provided to transmit
axial forces between the two parts of the roller body. In this manner only the
mechanical connection between the two parts of the roller body is obtained by the
threaded elements, whereas the clamping is obtained by means of mechanical securing
elements arranged in the outer periphery of the roller.
Document EP-A-0 040 808 shows a multi-part roll comprising a hollow
cylindrical axially extending roll body with a pair of ends spaced apart in the
axial direction. A journal is connected to each of the ends of the roll body in
a form-locking manner and the axes of the journals are in longitudinal alignment
and define the axis of rotation of the roll. This system is quite cumbersome and
complex and does not avoid the above-cited drawbacks.
The present applicants have designed, tested and embodied this invention
to overcome all the shortcomings subject to complaints in the state of the art
and to achieve further advantages in view of the urgent requests received in this
connection from persons working in this field.
This invention is set forth and characterised in the main claim,
while the dependent claims describe variants of the idea of the main embodiment.
The purpose of this invention is to achieve a system for installation
of the rolling rings on the relative supporting half-shafts which is suitable to
ensure considerable resistance to the deflections under load, particularly in
the zones where the maximum stresses take place in a direction transverse to the
axis of the half-shafts themselves.
Another purpose is to employ an auxiliary intermediate element for
the coupling of the two half-shafts, onto which auxiliary element is discharged
a great part of the rolling stresses, this element therefore in this case being
the element most subject to wear and consisting of an element which can be readily
and economically maintained or replaced.
Furthermore, according to the invention a mechanical continuity is
obtained between the two half-shafts just as if they consisted of one single shaft.
According to the invention the two half-shafts to which the rolling
ring is keyed are caused to cooperate together by means of a male/female coupling.
In other words, the inner terminal part of the half-shaft acting
as a male element is coupled to the inner terminal part of the half-shaft acting
as a female element so as to determine an at least partial superimposing of the
two terminal parts so as to create mechanical continuity.
According to the invention this superimposing covers advantageously
the greater part of the axial extent of the rolling ring; this situation leads
to a considerable increase of the resistance to transverse stresses, especially
in the zones most subjected to deflections under load.
According to the invention the coupling between the two half-shafts
is of a tapered type; in other words, the two terminal parts of the half-shafts
which are inserted into each other have a tapered conformation of a mating type
so as to ensure a tapered engagement.
According to a preferred embodiment of the invention a tapered sleeve
suitable to withstand the deflections and stresses under load which are caused
during the rolling is placed between the two terminal portions of the half-shafts
and substantially along the whole zone of the superimposing of these terminal
This tapered sleeve prevents direct contact between the coupled surfaces
of the half-shafts, thus obviating wear and deformations of those parts.
This wear and the deformations arising from the stresses and deflections
under load are therefore mostly transferred onto the tapered sleeve, which, however
is an element which can be readily and economically maintained and replaced.
The attached figures are given as a non-restrictive example and show
two preferred embodiments of the invention as follows:-
- shows a half section/half view of a preferred form of embodiment of the invention;
- shows a part of a variant of Fig.1.
A rolling roll 10, of which the essential parts are shown in Fig.1,
includes a rolling ring 11 that is keyed to a pair of half-shafts 12, namely a
righthand half-shaft 12a and a lefthand half-shaft 12b respectively.
The description in this case concerns a rolling roll 10 having a
horizontal axis, but the same considerations are applicable also where the rolling
roll has a vertical axis, in which case it will be necessary to take into consideration
an upper half-shaft and a lower half-shaft.
According to the invention the two half-shafts 12a-12b are coupled
together with a male/female coupling of a tapered type.
In this case, in particular, the inner terminal part 13b of the lefthand
half-shaft 12b acting as a male element is coupled to the inner terminal part 13a
of the righthand half-shaft 12a acting as a female element so as to define a zone
of superimposing and reciprocal support having an axial length "l".
This zone of superimposing covers advantageously the greater part
of the axial extent of the rolling ring 11 so as to create a zone of high resistance
to transverse stresses and to deflections under load.
So as to provide the tapered coupling, a first embodiment of the
invention shown in Fig.2 arranges that the cooperating surfaces 14a and 14b of
the two half-shafts 12a-12b have a mating tapered conformation so as to be able
to obtain the desired coupling.
According to the preferred embodiment of Fig.1 a tapered sleeve 15
suitable to withstand the deflections under load and the transverse stresses during
working is placed between the coupled terminal parts 13a-13b of the relative half-shafts
The tapered sleeve 15 is an element which can be readily and economically
maintained and/or replaced and therefore enables working conditions to be ensured
which are always substantially the best.
This tapered sleeve 15 is keyed advantageously in this case to the
inner terminal part 13b of the lefthand half-shaft 12b, an injection of oil being
made available to assist.
According to a variant a conduit 20 is provided which communicates
with an attachment 21 positioned on the drive side of the rolling roll 10 so as
to feed and replenish the oil for keying of the tapered sleeve 15 to the relative
According to the invention the union and constant engagement during
all the working steps, the recovery of the play due to the taper and the transmission
of the motive torque between the two half-shafts 12a-12b are ensured by a hydraulically
pre-loaded tie rod 16 extending along the axis of the two half-shafts 12a-12b.
This tie rod 16 is clamped in this case at the outer end of the lefthand
half-shaft 12b by a clamping nut 17 and is screwed onto the righthand half-shaft
12a so as to cause a loading to the desired tension between two half-shafts 12.
The half-shafts 12a-12b include respective lateral flanges 18 with
which there cooperate by contact the lateral surfaces 19 of the rolling ring 11.
These lateral flanges 18 are shaped in such a way as to ensure in
each step a constant contact with the lateral surfaces 19, thus providing by friction
a transmission of the torque to the rolling ring 11.