ROULEAU A FLEXION COMPENSEE, DE PREFERENCE A SURFACE SOUPLE, POUR CALANDRE

DEFLECTION-COMPENSATED, PREFERABLY SOFT-SURFACE ROLL FOR USE IN A CALENDER

Abrégé anglais

ABSTRACT OF THE DISCLOSURE:
A deflection-compensated roll for use in a calender,
comprising a stationary axle upon which is rotatably mounted a
shell, characterized in that: The roll comprises at least
two mutually independently controllable compensation means,
one of the compensation means consisting of a piston provided
with a slide shoe which abuts on the inner surface of the
shell, the piston being a continuous stip-like piston extending
over the entire length of the deflection-compensated roll,
the one compensation means substantially compensating for the
deflection due to the proper weight of the roll, and the other
of said compensation means consisting of a pressurizable ring
sector shaped gap between the shell and the axle, the other
compensation means substantially compensating for the deflec-
tion caused by the line pressure loading of the calender nip.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows :
1. A deflection-compensated roll for use in a
calender, comprising a stationary axle upon which is rotatably
mounted a shell characterized in that:
- the roll comprises at least two mutually indepen-
dently controllable compensation means,
- one of said compensation means consisting of a piston
provided with a slide shoe which abuts on the inner surface of
said shell, said piston being a continuous strip-like piston
extending over the entire length of the deflection-compensated
roll, said one compensation means substantially compensating
for the deflection due to the proper weight of the roll, and
- the other of said compensation means consisting of
a pressurizable ring sector shaped gap between said shell and
said axle, said other compensation means substantially compen-
sating for the deflection caused by the line pressure loading
of the calender nip.
2. A deflection-compensated roll according to claim
1, wherein said roll has a soft covering mounted on said shell.

Description

1~70535
The present invention relates to a deflection-
compensated roll for use in a calender, in particular in a
calender such as has been specified in Canadian patent applica-
tion No. 280,333, having as inventor Matti Kankaanpaa.
In the application 280,333 a so-called supercalender
belonging to a paper machine and intended for the burnishing of
the paper web has been disclosed, comprising a number of hard
rolls and a substantially equal number of soft rolls, such as
paper-coated rolls, cooperating with the hard rolls. It is a
substantially characteristic feature of the main invention that
the hard rolls have been disposed upon each other toconstitutea
stack wherein there are formed hard nips, and that in connec-
tion with the topmost and/or lowermost intermediate roll in the
stack constituted by hard rolls there have been formed, in ad-
dition to a hard nip between two hard rolls, at least two soft
nips wherein one of the tworollsis a soft roll, most appropri-
ately a paper-coated roll.
The object of the present invention is to accomplish
improvements in the rolls employed in the above-defined
calender and in other equivalent calenders, particularly in
soft rolls which define soft nips together with hard rolls be-
longing to the calender. In a calender according to applica-
tion No. 280,333, the soft rolls will be so located that their
axis and the nip defined by them are not in a vertical plane.
Furthermore, the loadin~ of the soft rol~s has been arranged to
be adjustable. Owing to these circumstances the direction of
the resultant from the proper weight of the rolls and the line
pressure load is subject to change as the nip loadings are
changed. Thereby the control of the calender rolls' deflection
and hereby that of the distribution of line pressure in the nips
defined by the soft roll~ becomes very difficult and very com-
plicated. The object of the invention is in fact, to provide a
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~070535
new calender roll by the aid of which the disadvanteges
mentioned may be avoided.
Therefore, according to the present invention, there is
provided a deflection-compensated roll for use in a calender,
comprising a stationary axle upon which is rotatably mounted
a shell characterized in that the roll comprises at least two
mutually independently controllable compensation means, one of
the compensation means consisting of a piston provided with a
slide sho~ which abuts on the inner surface of the shell, the
lo piston being a continuous strip-like piston extending over the
entire length of the deflection compensated roll, the one com-
pensation means substantially compensating for the deflection
due to the proper weight of the roll, and the other of the com-
pensation means consisting of a pressurizable ring sector shap-
ed gap between the shell and the axle, the other compensation
means substantially compensating for the deflection caused by
the line pressure loading of the calender nip.
In the following, the invention shall be described in
detail with reference to an embodiment example of the invention
presented in the figures of the attached drawing, but to which
the invention is not confined in any way.
FIGURE 1 presents, in schematic elevational view, a
calender wherein a deflection-compensated roll according to
the invention is used.
FIGURE 2 shows the cross-section of the deflection-
compensated roll of the invention.
FIGURE 3 shows a central axial section of the deflec-
tion-compensated roll of the invention.
In Figure 1 an embodiment of the calender is depicted
wherein a deflection-compensated roll according to the inven-
tion is applied. The calender rolls 1, 2, 5 and 6
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'1070535
are hard rolls, for instance die-cast rolls. Rolls 1 and 2
are large-diameter rolls (radius Rl). The roll 2 has been
provided with a drive means 40, which has been symbolically
depicted. It should be observed in this connection that the
large diameter 2Rl of the rolls 1 and 2 makes their deflection
rather small however, even if they should be asymmetrically
loaded.
The rolls 10 are so-called paper rolls, which are
commonly employed in supercalenders, and they have been
provided with deflection compensation in a manner which will
be apparent later on. The deflection-compensated soft rolls
10 are also provided with force means 28, 29 and lever arms
30-33 visible in Figure 1, the latter being pivoted by axles
35 and 36 to the calender frame and allowing the rolls 10 to
be distanced as is found suitable from the surface of the
roll 1, or 2, as the case may be. The rolls 10 may be urged
against the hard rolls 1 and 2 by means of the force means
28, 29 in order to obtain the desired line pressure of the
calender nips N.
It is possible, by varying the placement of the
soft rolls 10 and the force directed thereupon by means of
the arms 30-33, to influence not only the nip pressures of
the soft nips N, but also within rather wide and variable
limits the nip pressures of the hard nips N. It follows
that by varying the difference and mutual proportion of the
working pressures Pl and P2 of the force means 28, 29 the
calendering event may be influenced within very wide limits.
The means controlling the forces Pl and P2 have been
schematically indicated by the block 50 in Figure 2. The
path of the web through the calender of ~igure 1 is illus-
trated by arrows Win - WOUt.
3 _

~070535
The deflection-compensated roll 10 of the invention
comprises a soft paper covering 11, under this a metallic
shell 12. The paper covering 11 has been affixed upon the
shell 12 by means of the tightening nut 16. The roll of the
invention comprises, furthermore, a stationary, solid axle 14,
upon which the roll shell 11, 12 has been arranged with the
aid of the bearing 15 to be rotatable.
As shown in Figures 2 and 3, in view of compensating
for the deflection caused by the proper weight of the roll
there is in connection with the axle 14, a lathe-like piston
13, to which a slide shoe 22 has been attached, this latter
abutting on the inner surface of the roll shell 12. Behind
the lathe-like piston 13 there is a pressure chamber, into
which liquid may be conducted under desired pressure through
the bore 17. The slide shoe 22 and piston 13 constitute the
compensation zone a, with the aid of which the deflection
arising from the proper weight of the roll is compensated
in the direction B. According to the invention, in connection
with the roll there has also been provided at least one
further compensation zone ~, consisting of a pressure chamber
20, confined by sealing strips 21.
Into the chamber confined by the outer surface of
~, the above-mentioned stationary axle 14 and the rotating roll
shell 12, and by the seals 21, a pressurized fluid of desired
pressure is conducted through the bores 19. The leakage
. oil draining passage has been indicated by the reference
numeral 18. By means of the compensation zone ~ constituted
by thc pressure chamber 20, the deflections of the roll 10
caused by the line pressure loading of the calender nip N
can be compensated in the direction C.
_ 4

l07as3s
By using at least two compensating zones ~ and ~
arranged as taught by the present invention, one is enabled
by controlling the action pressure of these zones independent
of.each other, to compensate for the deflections of the
calender roll in all and any different loading situations,
and to arrange the line pressure in the calender nip in
question to have such distribution as is desired.
The invention is in no way confined to the details
described in the foregoing by way of example only, and which
may vary within th~ inventive idea defined by the claims
following below.
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