[0001] The invention concerns a method for computing and regulation of the distribution
of linear load in a multi-nip calender, wherein the material web to be calendered
is passed through the nips in a set of rolls that is placed in a substantially vertical
position, which set of rolls is formed by a variable-crown upper roll, a variable-crown
lower roll and by at least two intermediate rolls provided with support cylinders
and fitted between the upper and lower rolls, in which connection all the rolls in
the set of rolls are supported so that, when the nips are closed, the bending lines
of the rolls are curved downwards.
[0002] Further, the invention concerns an arrangement for computing and regulation of the
distribution of linear load in a multi-nip calender meant for calendering of paper
or board, which calender comprises a set of rolls which is mounted on the frame of
the calender in a substantially vertical position and which set of rolls includes
a variable-crown upper roll, a variable-crown lower roll as well as one or several
intermediate rolls fitted between the upper roll and the lower roll, in which connection
the means of suspension of the intermediate rolls are provided with support cylinders,
and all the rolls in the set of rolls are supported so that, when the nips are closed,
the bending lines of the rolls are curved downwards.
[0003] Further, the invention concerns a multi-nip calender for carrying out the method
in accordance with the invention.
[0004] In conventional supercalenders, when the nips are closed, the set of rolls is supported
from outside the zone of treatment of the web by means of forces which are substantially
equal to the what is called pin load applied to the bearing housings of the rolls
during running, or which are lower than said pin load. The pin load is commonly defined
so that it includes the weight of all of the auxiliary equipment connected with the
bearing housings of the roll, such as gap shields, doctors, and so-called take-out
leading rolls, and also the weight of the portion placed outside the web width and
the weight of the bearing system. This prior art has been described best in the paper
by
Rolf van Haag: "Der Weg zum Load Control-System"; Das Papier, 1990, Heft 7, in which the regulation of the linear load in a conventional supercalender is
described. In these calenders, the rolls are positioned one above the other so that
their middle portions are curved upwards or, in a very rare special case, are fully
straight. The intermediate rolls do not bend in the same way, as compared with one
another. Owing to the mode of running, the nip loads in the set of calender rolls
are always such that the roll masses occurring in the area of the web to be calendered
always act with full effect upon all the nip loads placed underneath the roll concerned.
In such a mode of running, it is assumed that the set of rolls is curved in such a
way during running that the rigidities of the rolls do not have a substantial effect
on the uniformity of the linear loads, and attempts are made to operate the calender
based on this assumption so that exclusively the linear loads of the upper roll and
of the lower roll are regulated on the basis of measurements of quality.
[0005] In the
Finnish Patent No. 96,334 and in the equivalent
US Patent No. 5,438,920, a calendering method and a calender that applies the method have been described,
which calender comprises a variable-crown upper roll, a variable-crown lower roll
and a number of intermediate rolls placed between the upper roll and the lower roll
in nip contact with each other, said rolls having been arranged as a substantially
vertical stack of rolls on the frame of the calender, the material web to be calendered
being passed through said nips. In said patents, an idea was suggested according to
which the nip load produced by the masses of the rolls in the stack of rolls was eliminated
in the desired way so that all the nips in the calender could be loaded with the desired
load, which load was, in a preferred alternative embodiment, equally high in all nips.
Thus, the calendering potential could be utilized substantially better than in the
earlier calenders. It was one of the basic ideas in said prior-art calender that rolls
bending in the same way were employed in the calender. In said publications, the conduct
of such substantially equally bending rolls in the calender and the simple possibility,
permitted by said rolls, of relieving the whole mass of the roll were described, in
which case said prior-art calender and calendering method differ essentially from
the first-mentioned German prior art in the very respect that the effect of the masses
of the rolls on the linear loads in the lower nips can be regulated freely.
[0006] The prior art described above involves an essential problem. If it is assumed that
the natural deflections of the intermediate rolls in the calender without linear loads,
i.e. when the nips are open, and the rigidities of the rolls as well as the masses
are different, first it is to be stated that such rolls do not comply with those described
in said
FI Patent 96, 334 or
US Patent 5,438,920, in which patents all of the intermediate rolls had substantially equal deflections.
In reality, the manufacture of such rolls, which substantially meet the absolute requirement
stated in said publications without separate operations, is very difficult and also
expensive, in which connection it has been ascertained that an entirely trivial algorithm
of regulation of linear loads, which does not take into account minor differences
between the rolls, is not adequate from the point of view of reliable operation of
the calender.
[0007] The object of the present invention is to provide a solution for the problems related
to prior art by developing a novel mode of thinking, which takes into account the
properties of deflection of the rolls. One object is to provide an improvement over
the calender concept described in the
FI Pateict 96,334 and
US Patent 5,438,920, in particular in respect of the way in which the distribution of linear load can
be brought under control in the desired way.
[0008] In view of achieving this object, the method in accordance with the invention is
mainly characterized in that, in the computing and regulation of linear loads, the
physical properties affecting the bending of each intermediate roll under load, such
as bending rigidity, mass, shape, and material properties, are taken into account,
and the ratio of the linear loads applied to the intermediate rolls, the own weight
of the rolls, and of the support forces applied to the rolls is regulated so that
the set of rolls is in a state of equilibrium and in a predetermined state of deflection.
[0009] On the other hand, the arrangement in accordance with the invention is mainly characterized
in that the arrangement includes an automation system and a computing unit, which
have been fitted, in the computing and regulation of linear loads, to take into account
the physical properties affecting the bending of each intermediate roll under load,
such as bending rigidity, mass, shape, and material properties, and to regulate the
ratio of the linear loads applied to the intermediate rolls, the own weight of the
rolls, and of the support forces applied to the rolls so that the set of rolls is
in a state of equilibrium and in a predetermined state of deflection.
[0010] The method in accordance with the invention takes into account the properties of
rolls of all types, and, thus, in an embodiment of the invention, in the method, in
the set of rolls in the calender, intermediate rolls are employed whose bending properties
are different from roll to roll.
[0011] In the computing in accordance with the method and the arrangement, the set of rolls
can be treated as a single unit. On the other hand, the computing can also be carried
out individually in respect of each pair of rolls.
[0012] The intermediate rolls in the set of rolls are freely moving, so that just forces
are applied to the rolls, but the rolls are not held in position.
[0013] By means of the method and the arrangement in accordance with the invention and by
means of the calender intended for carrying out the method, significant advantages
are obtained in particular in the respect that, by means of the arrangement in accordance
with the invention, the linear loads in each nip can be regulated to the desired level.
The arrangement takes into account and computes the deflection lines of the intermediate
rolls and the loads of the relief cylinders corresponding to said lines. The rigidities
of the intermediate rolls and the differences in the natural deflections of the rolls
arising from differences in mass can be compensated for readily in the arrangement
by regulating the support forces of the roll support cylinders. Thus, when an arrangement
in accordance with the present invention is employed, the deflection lines of all
of the intermediate rolls do not have to be identical. The method and the arrangement
of the invention can be applied both with a traditional mode of running of a multi-nip
calender, in which the paper web runs through all nips, and to a modified mode of
running, in which the paper web is passed through certain, desired nips only. Further
advantages and characteristic features of the invention will come out better from
the following detailed description of the invention.
[0014] In the following, the invention will be described by way of example with reference
to the figures in the accompanying drawing.
Figure 1 is a general illustration of the arrangement in accordance with the invention
which is applied in a multi-nip calender for computing and regulation of the distribution
of linear load.
Figures 2A, 2B and 2C are exemplifying illustrations of the sorts of regulation of
the distribution of linear load in the machine direction that can be achieved by means
of the arrangement in accordance with the invention.
Figures 3A, 3B and 3C illustrate the effects of different calendering parameters on
the surface properties of paper.
Figure 4 is a schematic illustration of the relative arrangement of the data bases
included in the automation arrangement in accordance with the invention.
Figure 5 is a schematic illustration of a four-roll calender that carries into effect
the method in accordance with the invention.
Figure 6 is a schematic illustration of an alternative mode of loading in a multi-roll
calender in which the set of rolls in the calender is treated by pairs of rolls.
Figures 7A, 7B and 7C are schematic side views illustrating alternative embodiments
of the set of rolls in a multi-roll calender in which a mode of loading described
in relation to Fig. 6 is employed.
Figure 8 shows a schematic block diagram that illustrates a model of computing in
the arrangement in accordance with the invention.
[0015] Thus, Fig. 1 is a general view of the arrangement in accordance with the invention,
and in this figure the calender is denoted generally with the reference numeral 10,
the automation system included in the invention with the reference numeral 30, and
the computing unit included in the automation system with the reference numeral 40.
The calender 10 shown in Fig. 1 has a construction similar to that described, e.g.,
in the
FI Patent 96,334, and, thus, the calender comprises a calender frame 11, on which the set of rolls
12 consisting of a number of rolls has been installed substantially in the vertical
plane. The set of rolls 12 comprises an upper roll 13, a lower roll 14, and a number
of intermediate rolls 15...22 fitted between the upper roll and the lower roll one
above the other, which rolls are, in the situation illustrated in Fig. 1, in nip contact
with each other. The paper web W is passed over alignment, spreader and take-out leading
rolls into the upper nip N
_{1} and further through the other nips N
_{2}...N
_{8} in the calender and finally out through the lower nip N
_{9}. In the way illustrated in Fig. 1, the paper web W is taken, in the gaps between
the nips N
_{1}...N
_{9}, apart from the faces of the calender rolls by means of take-out leading rolls.
[0016] The upper roll 13 in the calender is a variable-crown roll, for example a roll adjustable
in zones, whose bearing housing 131 has been attached directly to the calender frame
11. The axle of the variable-crown upper roll 13 has been mounted in said bearing
housing 131, and, in the normal way, the roll is provided with inside loading means,
for example zone cylinders, by whose means the deflection of the roll mantle can be
regulated in the desired way.
[0017] In a similar way, the lower roll 14 in the calender is a variable-crown roll, in
particular a roll adjustable in zones, whose mantle has been mounted revolving on
the roll axle and which roll 14 is provided with inner loading means, for example
zone cylinders, by whose means the deflection of the roll mantle can be regulated
in the desired way. The axle of the lower roll 14 has been mounted in bearing housings
141, which have been mounted, in the way shown in Fig. 1, on loading arms 142, which
have been attached to the calender frame pivotally by means of articulated joints
143. Between the calender frame 11 and the loading arms 142, lower cylinders 144 have
been mounted, by whose means the lower roll 14 can be shifted in the vertical plane.
Thus, the set of rolls 12 can be loaded by means of the lower cylinders 144, and,
further, by means of said lower cylinders 144, if necessary, it is possible to open
the set of rolls 12. By means of the zone cylinders of the variable-crown upper and
lower rolls 13, 14, in the method and the arrangement in accordance with the invention,
a necessary correction and regulation of the cross-direction profile of the paper
web W can be carried out.
[0018] Between the upper and the lower rolls 13,14 in the calender, a number of intermediate
rolls 15...22, which are in nip contact with each other, have been fitted, as was
already stated above. In the following, exclusively the topmost intermediate roll
15 will be examined, and the related constructions are described in more detail with
the aid of reference numerals. A corresponding description can also be applied to
the other constructions of intermediate rolls in the calender. Said intermediate roll
15 has been mounted from its ends revolving in bearing housings 151, which have been
mounted on lever arms 152, which have been mounted pivotally on the calender frame
11 by means of articulated joints 153 fitted in the axial direction of the roll 15.
The lever arms 152 are provided with support means 154, which are hydraulic cylinders.
Thus, said cylinders 154 are attached from one end to the lever arms 152 and from
the opposite end to the calender frame 11.
[0019] By means of the cylinders 154, a support force is applied to the support constructions
of the roll 15, by means of which force, the loads caused by the weights of the roll
15 and of the related auxiliary equipment, such as the take-out leading roll 155,
however, always at least the weight of the auxiliary equipment connected with the
roll as added with the weight of the parts placed outside the web, can be compensated
for and supported in the desired and necessary way. The support can also be carried
out so that the loads are supported completely, in which case the weights of the roll
15 and of the connected auxiliary equipment have no effect of increasing the nip load.
If such complete support is carried into effect in respect of all of the intermediate
rolls 15...22, the linear load in each nip N
_{1}...N
_{9} can be made substantially equally high.
[0020] Fig. 2A is a schematic illustration of the situation of loading in the set of rolls,
in which connection each nip N
_{1}...N
_{9} has an equally high linear load. In this connection, a new term is also introduced
in calendering technique, i.e. loading angle α, because this novel mode of loading
cannot be illustrated unequivocally in traditional ways. The loading angle α illustrates
the distribution of linear load in the set of rolls from nip to nip, and in the -case
of Fig. 2A, i.e. in a case of complete relief, the loading angle α = 90°. By means
of said loading angle of 90°, compared with conventional calenders, a significant
increase in the calendering potential is obtained. This can be utilized in order to
increase the running speed and the productivity.
[0021] The magnitude of the linear load can be regulated fully freely in order to achieve
the desired calendering effect, and, in particular in the case of "full relief", i.e.
with a loading angle of α = 90°, the calendering effect can be regulated in the way
illustrated in Fig. 2A by way of example. A high linear load and a high calendering
effect a are employed in order to maximize the running speed of the calender, the
productivity, and the paper quality. A low linear load and a low calendering effect
a' are needed under different conditions and in different production stages, such
as in matt calendering, in optimizing of quality, in stages of starting up and running
down, and in situations of web break. By means of a the solution in accordance with
the present invention, a very low calendering effect can be achieved in each nip in
the calender, as is illustrated in Fig. 2A by way of example.
[0022] Fig. 2B illustrates a situation in which, as compared with a calender with a conventional
mode of loading in which the loading angle α is, e.g., 54°, in a mode of running in
accordance with the present invention, a loading angle α = 90° is employed. As is
indicated clearly by Fig. 2B, with a mode of running in accordance with the present
invention, a significantly lower level of linear load is needed to produce similar
properties of quality of paper. In this way, it is possible, for example, to minimize
the strain applied to the soft-faced rolls in the calender, such as polymer-coated
rolls, in particular in the lower part of the set of rolls.
[0023] The loads produced by the masses of the intermediate rolls 15...22 in the set of
rolls 12 and by the masses of the auxiliary devices connected with said rolls can,
if necessary, also be relieved partially, or so that exclusively the pin loads are
relieved, in which case, in respect of the distribution of linear load in the set
of rolls, for example, a situation as shown in Fig. 2C is reached, in which the loading
angle α can be adjusted, e.g., in the range 75°...80°
. Thus, in said situation, the linear loads are always increasing in the nips when
moving towards a lower nip.
[0024] In conventional and traditional supercalenders, the loading angle has, as a rule,
been in the range 45°...55°, and the magnitude of this loading angle has been dependent
on the size of the calender, i.e. mainly on the number of rolls. In the method in
accordance with the present invention, the magnitude of the loading angle α can be
adjusted quite freely, and by means of this adjustability of the loading angle a considerable
advantage and a remarkable improvement are achieved over earlier solutions. The loading
angle α can be used as an active variable in fine adjustment of the differences between
different faces of the paper. Adjustment of two-sidedness has a significant effect
on the properties of quality of paper, and in this way, by means of the present invention,
it is possible to produce paper of uniform quality reel after reel. A corresponding
property has not been suggested anywhere else previously.
[0025] The support can, of course, also be accomplished, for example, as a what is called
"excessive relief", wherein the loading angle α is larger than 90°. In such a case,
it is possible to reach a situation in which a lower nip always has a lower linear
load than the nip placed above has. Such an embodiment has, however, not been illustrated
in the figure.
[0026] In order to establish the significance of the loading angle α and of its adjustability
as compared with other calendering parameters or variables, quite an extensive test
program has been carried out with a test machine, and an example of the test results
is given in Figs. 3A, 3B and 3C, which illustrate the effects of different calendering
parameters with different paper grades. In Fig. 3A the paper grade is SC paper, in
Fig. 3B the grade is LWC paper, and in Fig. 3C the grade is WFC paper. The effects
of different factors on the surface properties of paper (gloss, roughness/smoothness)
were determined by means of the results, which were obtained by changing the calendering
parameters to a certain extent. The variables that were used were running speed, linear
load, temperature, and loading angle, as follows:
Speed: |
change in speed 200 metres per minute |
Linear load: |
change in load 50 kN/m |
Temperature: |
change in surface temperature of heated roll 15 °C |
Loading angle: |
change in loading angle from 50° to 90° (50° represents the loading with a traditional
mode of supercalendering, and 90° represents an angle which can be obtained with the
method in accordance with the present invention) |
[0027] As can be seen clearly from Figs. 3A, 3B and 3C, the effect of a change in loading
angle on improvement of the surface properties of paper is higher than with any other
calendering parameter.
[0028] Fig. 1, and so also Figs. 2A, 2B and 2C, illustrate an embodiment in which the set
of rolls 12 consisting of the rolls has been installed substantially vertically. The
solution is, of course, not confined to such an embodiment only, but the set of rolls
can be placed in an obliquely vertical position at least to some extent diverging
from the vertical position. Of the rolls included in the set of rolls 12, one or several
may be soft-coated polymer rolls and/or paper rolls, fibre rolls or other soft-faced
rolls. In the exemplifying embodiment shown in Fig. 1, the upper and the lower roll
13,14 are provided with a soft polymer coating, the first, third, sixth, and eighth
intermediate rolls 15,17,20, and 22 are hard-faced chilled rolls, and the second,
fourth, fifth, and seventh intermediate rolls 16,18,19,21 are soft-coated polymer
rolls. The number of the intermediate rolls or the relative sequence and arrangement
of the soft-faced/hard rolls is, however, in no way confined to the exemplifying embodiment
of Fig. 1.
[0029] In the method in accordance with the present invention, a sittlation corresponding
to a normal production situation is examined, in which case the set of rolls 12 is
closed in the way shown in Fig. 1 and the rolls 13...22 are under load in contact
with one another. In the way shown in Fig. 1, the automation system 30 included in
the arrangement in accordance with the invention has been connected to the support
cylinders 154 to measure and to control the loads of the relief cylinders. In the
method to be examined, in the nips N
_{1}...N
_{9} in the set of rolls 12, in the running direction of the paper web W, a uniform or
different, desired distribution of linear load is formed so that in the automation
system 30 the deflection lines of the intermediate rolls 15...22 and the corresponding
loads of the cylinders 154 of support of the intermediate rolls are computed. The
support cylinders 154 and the lever arms 152 are used for supporting the masses of
the intermediate rolls 15...22 and the masses of the auxiliary devices connected with
the intermediate rolls.
[0030] As was already stated with reference to Figs. 2A, 2B and 2C, the distribution of
linear load in the machine direction is regulated by supporting the masses of the
rolls and of the connected auxiliary devices completely. Thus, besides the masses
of the intermediate rolls, by means of the support cylinders 154 and the lever arms
152, the masses of the auxiliary devices connected with the lever arms of each intermediate
roll, such as take-out leading rolls, possible doctors, etc., are also supported.
The rigidities and masses of the intermediate rolls 15...22 are not equal from roll
to roll. Correcting of the errors in the cross-direction profiles of the deflection
lines of the rolls, arising from these differences in rigidity and mass, i.e. regulation
of the deflection lines of the intermediate rolls, is carried out by correcting the
loads of the support cylinders of the intermediate rolls from their nominal value
by means of the necessary term corresponding to the difference in pressure. The regulation
of the deflection lines of the variable-crown upper roll and lower roll 13, 14 is
carried out in the normal way by means of the zone cylinders in the rolls. When the
deflection lines of the variable-crown upper and lower roll 13, 14 are regulated so
that they are equal to the deflection lines of the intermediate rolls 15...22, it
is possible to give the set of rolls 12 the desired level of linear load in the machine
direction by hydraulically loading either the upper roll or the lower roll. In the
case of Fig. 1, this loading can be arranged by means of the lower roll 14, because
the loading cylinders 144 have been connected to act upon the lower roll.
[0031] In the method and the arrangement in accordance with the invention, the necessary
correction and regulation of the cross-direction profile of paper, i.e. of thickness
and/or glaze, is carried out by means of the zone cylinders in the variable-crown
upper and lower roll 13,14. In the intermediate nips, i.e. in the nips N
_{2}...N
_{8} between the intermediate rolls 15...22, correction of the cross-direction profile
can be carried out by means of regulation of the loading of the relief cylinders of
the intermediate rolls. The method in accordance with the invention and the related
computing of the distribution of the linear load in the set of rolls 12 can be applied
both to a traditional mode of running of a multi-nip calender, wherein the paper web
W runs through all of the nips N
_{1}...N
_{9}, and to a modified mode of running, wherein the paper web W is passed through certain
nips only. In the method in accordance with the invention, the automation system includes
programs of maintenance of the set of rolls, distributions of linear load, roll parameters,
and recipe data bases, which, together with the program of computing of the distribution
of linear load, permit computing of the distributions of linear load specifically
for each paper grade. Further, for maintaining the changes in the set of rolls in
the calender and for monitoring the stock of rolls, there are program routines of
their own.
[0032] The distribution of linear load in the set of rolls 12 and the support forces to
be passed to the support cylinders of the intermediate rolls 15...22 are computed
either in the automation system 30 or in a separate computing unit directly connected
with said system. The computing model determines the rigidity and the mass distribution
of the set of rolls 12 in the calender 10 consisting of chilled rolls and polymer
rolls as well as the rigidity of the nips N
_{1}...N
_{9} between the rolls. Further, in the computing, the locations and masses of the outside
masses connected with the set of rolls are determined, the effect of temperature on
the modulus of elasticity is taken into account, the effect of the roll diameters
on the original modulus of elasticity is taken into account, a possible additional
linear load of the rolls and the separate effects of the centres of mass and gravity
of the roll ends at the tending side and at the driving side are taken into account.
The data employed in computing are divided into general calender-specific, nip-specific,
and roll-specific data. Thus, the starting-value data necessary for the computing
are defined in the roll data base 51, in the roll material data base 52, in the set-of-rolls
mass data base 53, in the data base of geometry of the articulated linkage in the
calender, i.e. in the set-of-rolls data base 54, as has been illustrated schematically
in Fig. 4. In the computing model applied in the invention, the computing is carried
out in two stages so that in the first stage the support pressures of the intermediate
rolls are optimized and correction coefficients are obtained for the variable-crown
upper and lower rolls. These data are utilized in the second stage of computing for
optimizing the distribution of linear load of the upper roll and the lower roll.
[0033] The way in which the calender in accordance with the invention can be made to operate
in the desired way, i.e. the way in which the forces that support the intermediate
rolls are determined, is derived from the procedure in accordance with the invention,
by whose means the ratio of the linear loads applied to the intermediate rolls, of
the weight of said rolls, and of the support forces applied to said rolls is adjusted
to such a level that a pre-determined state of deflection prevails in the area of
the set of rolls. In the determination of the deflection of each roll, it is also
possible to include a possible mode of grinding of the roll concerned or of the roll
in nip contact with said roll different from cylindrical shape, such as a positive
or negative crown.
[0034] When the basic load and the correction of linear load produced by means of the variable-crown
rolls operating as end rolls are taken into account in the solution of the equations
of deflection of the intermediate rolls, in every case it is possible to achieve such
a state of equilibrium for the set of rolls that the distributions of linear load
in the nips in the set of rolls correspond to the desired distribution of linear load.
[0035] The group of equations that has been formed and that illustrates the conduct of the
set of rolls can be solved convergently by means of commonly used numeric solution
algorithms of groups of equations. An example of this is Fig. 5, which illustrates
a four-roll supercalender, in which the set of rolls 100 comprises a variable-crown
lower roll 111, a variable-crown upper roll 112, and two intermediate rolls 113,114.
The nip load in the nips N
_{101},N
_{102},N
_{103} between the rolls is produced substantially as the spring force required to produce
an elastic compression of the coating on one of the rolls that form a nip. Since,
at each point, the force is proportional to the difference between the transitions
arising in the rolls at the nip, it can be concluded directly that at each point the
same load is achieved when the difference in transition at the points is the same,
i.e. when the deflection lines of the rolls are of equal shape and of equal magnitude.
Thus, the optimal relief or support of each roll is determined so that the bending
load that remains on each roll mantle produces an equally high deflection on all rolls.
[0036] Since, normally, the deflection forms of rolls are equal (paraboloidal), in the examination
referring to Fig. 5 the deflection of the roll will be described exclusively by means
of the deflection of the centre point of the roll.
[0037] The deflection of a roll as a result of a deflecting linear load produced on the
roll mantle can be expressed by means of the formula:
from which the load is obtained by means of the deflection:
Herein:
- δ_{t} =
- deflection of roll
- k =
- coefficient depending on mode of loading
- q_{ts} =
- linear load that deflects the roll
- E_{t} =
- modulus of elasticity of roll
- I_{t} =
- inertia of roll
[0038] The sum of the loads that deflect the intermediate rolls in the whole set of rolls:
- ΔQ =
- change in overall load in the area of the set of rolls
[0039] The load that deflects the roll mantle expressed by means of component loads:
- G_{tv} =
- weight of roll mantle
- q_{ty} =
- linear load in upper nip of roll
- q_{ta} =
- linear load in lower nip of roll
- q_{ti} =
- additional linear load arising from other factors in the area of the roll mantle
[0040] When it is taken into account that, in an intermediate nip between rolls, the upper
and lower nip loads of adjacent rolls are of equal magnitude, the sum of the loads
that deflect the intermediate rolls in the whole set of rolls is obtained as:
- q_{yy} =
- linear load in the upper nip of the set of rolls
- q_{aa} =
- linear load in the lower nip of the set of rolls
[0041] When the deflections of the rolls are denoted equal and when they are substituted
further, what is obtained is:
[0042] When this is substituted further in the formula of the load that deflects a roll,
what is obtained is:
[0043] Regarding the equilibrium of forces in a roll, the required support force per side
is solved:
- F_{tk} =
- support force of roll per side
- L =
- nip length
- G_{tp} =
- weight of end parts of roll per side
[0044] The computing of the support forces of the set of rolls in the calender, expressly
of the whole set of rolls, is based on knowledge of the exact physical properties
of the rolls, i.e. the conduct of all the rolls is known when deflecting loads of
different magnitudes are applied to said rolls. It is the basis of the computing that
the bearing support forces applied to each roll are determined so that the whole set
of roll obtains an equally high calculatory deflection. Thus, by means of regulation
of the support forces, it is possible to affect the ratio of the upper nip load and
the lower nip load at an individual roll so that the sum of these loads, together
with the own mass of the roll, produces the same predetermined deflection in each
individual roll.
[0045] The computing can be applied to a set of rolls of any kind whatsoever in a calender,
which set of rolls is placed in a substantially vertical position, in which set of
rolls the upper roll is an adjustable-crown roll and the lower roll likewise an adjustable-crown
roil, the axial distribution of support forces of said upper and lower roll being
adjustable, and in which set of rolls there are at least two intermediate rolls between
the upper roll and the lower roll. Further, it is an important requirement that all
the rolls in the set of rolls are supported so that their deflection lines are downwards
curved when the nips are closed.
[0046] It is an important characteristic feature of the method, the arrangement, and the
calender in accordance with the invention that, in the computing of the linear loads
in the set of rolls, the physical properties of each intermediate roll that affect
the deflection under load, such as bending rigidity, mass, shape, and material properties,
are taken into account.
[0047] It is a further property that the bearing support forces of the intermediate rolls
are determined by means of computing so that the overall load applied to each intermediate
roll subjects each intermediate roll substantially to such a calculatory deflection
that the deflection forms of the contact faces of each roll and of the roll in contact
with said roll in a nip substantially correspond to one another.
[0048] The nip forces in a calender are regulated so that the difference between the nip
forces of the topmost nip and the lowest nip in the calender is determined to be at
the desired level. This means, in fact, the regulation of the loading angle α that
was described in relation to Figs. 2A, 2B and 2C.
[0049] In a summarizing way, it can be stated further that it is an essential feature of
the invention that all the intermediate rolls in the set of rolls are supported to
a greater extent than what is required by the pin forces (all mass outside the web).
In such a case, the deflection lines of the rolls are downwards curved and substantially
paraboloidal. The support forces of each intermediate roll are regulated so that the
deflection of the roll is adapted to the shapes of the other rolls in the set of rolls.
Thus, the computing is carried out by means of the deflections. In this way, a group
of equations is obtained in which the basic load between the rolls is determined so
that the deflections of all the rolls are equal. Thus, an equilibrium of forces is
produced in the set of rolls. As the loading angle α it is possible to use any loading
angle whatsoever, and the regulation of the loading angle α is carried out by means
of outside loading members through the lower roll and the upper roll. Thus, in the
regulation of the deflection, the variable is the support force with which the roll
is supported. The errors produced by the masses of the areas outside the web in the
distribution of linear load (and so also possible other errors in the distribution
of linear load) are corrected by means of the adjustable-crown upper and lower rolls.
[0050] As is shown in Fig. 6, the invention provides a novel possibility of taking care
of the loading and of the regulation of loading in the set of rolls in a multi-roll
calender by the pair of rolls, which makes the system of regulation simpler and easier
to carry into effect. As was already described earlier, in the present-day supercalenders,
as intermediate rolls, as a rule, rolls of two different types are employed, and the
rigidities of these two roll types are different. As the intermediate rolls, hard-faced
heatable rolls are used, on one hand, and soft-faced rolls are used, on the other
hand, which soft-faced rolls can be conventional paper rolls or fibre rolls, which
have been formed by fitting disks made of paper or of some other fibrous material
onto the roll axle. As soft-faced rolls, to-day, ever increasing use is made of polymer-faced
rolls, in which the roll frame consists of a tubular roll mantle. The rigidities of
rolls of the same roll type are substantially equal to one another, but, as was already
stated above, the roll types differ from one another essentially in respect of rigidity
and, thus, also in respect of the deflection arising from the own mass.
[0051] In a conventional supercalender, the set of rolls comprises a stack of rolls placed
in a substantially vertical or obliquely vertical position, wherein the rolls rest
one on the other and the pin loads applied to the bearing housings of the rolls have
been relieved hydraulically. The loading and profiling of the set of rolls is taken
care of by means of variable-crown upper and lower rolls.
[0052] In the alternative mode of loading shown in Fig. 6, the set of rolls is treated as
pairs of rolls 200, which consist of a more rigid roll 202 placed as the lower half
in the pair of rolls 200 and of a more flexible roll 201 placed as the upper half.
Thus, the deflection arising from the own mass of this upper roll 201 is higher than
the deflection of the lower roll 202 in the pair. The pairs of rolls 200 in the set
of rolls are substantially similar to one another, and they have equal, common deflections
depending on the masses and rigidities of the rolls 201,202.
[0053] To the bearing housings of the upper and more flexible roll 201 in the pair of rolls
200, for example hydraulically, a force F
_{2} is applied, by whose means, besides relief of the pin loads, the error in the distribution
of linear load between the rolls, which error arises from the different rigidities
of the rolls 201,202, is compensated. This can be illustrated by means of the formula:
wherein
- F_{2} =
- force applied to the bearing housings of upper roll
- m_{add2} =
- mass of the bearing housings and of the auxiliary devices attached to them as well
as the above error arising from different rigidities of the rolls
[0054] Thus, the upper roll 201 rests with its own weight m
_{2} (from which the pin loads have been "cleaned") on the lower roll 202 and applies
an even linear load m
_{2}/L to the lower roll, wherein L is the axial length of the nip N between the rolls
201,202. On the other hand, a force F
_{1} is applied to the bearing housings of the lower roll 202 in the pair of rolls 200,
by means of which force the masses of both rolls 101.102 in the pair of rolls 200
as well as the pin loads of the lower roll 202 are supported. This can be illustrated
by means of the formula:
wherein
- F_{1} =
- force applied to the bearing housings of the lower roll
- m_{1} =
- mass of lower roll
- m_{2} =
- mass of upper roll
- m_{add1} =
- mass of the bearing housings of the lower roll and of the auxiliary devices attached
to them.
[0055] Thus, in an optimal situation, between the separate pairs of rolls 200, no forces
arising from the masses of the rolls are effective at all. In the nip N between the
rolls 201,202 of the pair of rolls 200, exclusively the linear load arising from the
mass of the upper roll 201 is effective, for example about 10...20 kN/m. Owing to
the differences between individual rolls, the whole set of rolls must be treated as
a whole, and the reliefs of each roll must be optimized so that the cross-direction
profile of linear load of the whole unit is as straight as possible and the linear
load arising from the masses of the rolls is as low as possible. In this way, a set
of rolls with almost uniform loading is obtained, which set of rolls is, in the other
respects, loaded in the way described above. When, for example, a load of 300 kN/m
is considered as the load level, in every second nip there is a difference in loading
of about 5 per cent only, as compared with the preceding or the following nip, i.e.,
with existing rolls, a substantially even distribution of load is achieved.
[0056] Above, in connection with the description related to Fig. 6, for the sake of simplicity,
it has been assumed that the rigidities of the rolls 201,202 in the pair of rolls
200 are in a certain ratio to one another and that the rigidities of the rolls belonging
to the same type of rolls are equal to one another. However, as was established above
in relation to Fig. 5 clearly by means of computing, there would not seem to exist
any limitation arising from the mutual ratios of the extents of specific deflections
of the rolls. Thus any ratio of the rigidities of two rolls whatsoever can be compensated
by means of computing so that the magnitudes of the linear loads in the whole set
of rolls can be regulated so that they become substantially equal, with the exception
of the deviation caused by the internal nips in calculatory pairs of rolls.
[0057] When conventional upper and lower rolls, for example rolls adjustable in zones, are
used, a factor that limits uniform loading is the overall deflection of the intermediate
rolls. This limitation could, however, be compensated for so that, if necessary, the
lower roll is ground so that its diameter is smaller at the middle than at the ends
(negative crown), so that the attainable maximal deflection of the roll adjustable
in zones, together with the grinding shape, achieves the maximal possible deflection
of the set of rolls. In this connection, it should, however, be noticed that, in a
set of rolls of this type, the general direction of deflection of the rolls differs
in such a way from the direction of deflection of so-called conventional supercalenders
that the rolls are in a downwards curved position, in stead of the upward curve form
employed in a conventional supercalender.
[0058] In regulation of loading carried out by the pair of rolls, in the set of rolls in
a supercalender, compared with the illustration of Fig. 6, a difference is caused
by the reversing nip in the calender, i.e. the nip in which the side of calendering
of the web is changed. As a rule, this reversing nip is the middle nip in the supercalender.
This is illustrated in Figs. 7A, 7B and 7C, in which three alternative modes of loading
in said reversing nip are shown. In said figures, the pairs of rolls as shown in Fig.
6 and identical with one another are denoted with the reference numeral 200. In a
supercalender, the reversing nip is a nip that is formed between two soft-faced rolls
201, and in Figs. 7A, 7B and 7C this reversing nip is denoted with N
_{e}.
[0059] In the solution of Fig. 7A, this has been accomplished so that, in the "pair" of
rolls 200
_{e}, which is in this case formed by three rolls placed one above the other, the lower
roll 202, which is a hard-faced and, for example, heatable roll, has a higher rigidity
than the lower rolls in the other pairs of rolls 200. This is because the masses of
the two upper rolls 201 rest on the lower roll 202.
[0060] In Fig. 7B, a corresponding solution has been accomplished so that the upper soft-faced
roll 201
_{el} in the reversing nip N
_{e} is arranged as a variable-crown roll. In such a solution, the deflection of said
roll 201
_{e1} is corrected by means of the crown variation means fitted in the interior of the
roll, and the mass of the roll does not load the pair of rolls 200
_{e1} placed underneath by means of its weight.
[0061] In Fig. 7C, a corresponding solution has been accomplished so that the upper soft-faced
roll 201
_{e2} in the reversing nip N
_{e} has been arranged as a roll with such a rigidity that its deflection is the same
as the deflection of the whole pair of rolls 200,200e
_{2}. In such a case, said roll in the reversing nip does not cause any problem in the
regulation of the loading.
[0062] With reference to Fig. 8, in the computing, in accordance with the invention, first
the initial values of the rolls are defined, and on this basis the mathematical model
corresponding to the set of rolls is formed. The mathematical model is formed in compliance
with the number of rolls included in the set of rolls. The optimization computing
formed for the set of rolls uses these data as the starting data. In the optimization
computing that is to be carried out, the nip errors of the intermediate rolls are
minimized, which errors have been defined as deviations from the nominal form. The
resilience occurring between each nip and arising from the paper and from the coatings
is illustrated by a base constant, which is computed across the nip length. The effects
of the forces to be optimized on the linear load are determined in a response data
base, in which the unit response of the element of the nip of each intermediate roll
is indicated in a desired number of examination points. The effects of invariable
forces on the linear load are determined in a separate invariable-force data base,
which takes into account divided masses, point masses, and nips with invariable load.
Further, for the computing, the effects of the forces to be optimized on the restrictions
and the effects of backup forces on the tension restrictions are determined. Thus,
the assignment of optimization becomes a mathematical problem, in which the variables
are limited and determined by groups of equations. As a result of the computing, optimal
relief forces for intermediate rolls, optimal profiles of linear load and deflections
of rolls are obtained.
[0063] After the computing operation, the optimized support forces of the intermediate rolls
in the set of rolls of the calender are transferred to the support cylinders of intermediate
rolls, as is illustrated, for example, in Fig. 1. The optimized support forces of
intermediate rolls are also transferred to the program of computing of the zone pressures
of the variable-crown upper and lower rolls. The deflection values of the intermediate
rolls in the set of rolls are used for controlling and regulation of the variable-crown
upper and lower rolls. From the deflection values of the intermediate rolls, by means
of a separate computing program, the zone pressure corrections of the upper and the
lower roll are determined, which corrections are, in each particular case, added to,
or reduced from, each actual value of zone pressure. The distribution of linear load
in the set of rolls is controlled in the method in accordance with the invention so
that, by means of the user interface of the automation system, first the desired form
of the distribution of linear load is determined. After this, the automation system
and the included computing programs compute the above set values for the support pressures
of the intermediate rolls and for the zone pressures of the variable-crown upper and
lower rolls. The method in accordance with the invention also takes into account situations
of change in the set of rolls arising from change of roll or from a new mode of running
as well as any changes arising from said situations of change in the set-of-rolls
data base and in the parameter data bases and in the computing. Likewise, in its roll
and material data bases, the method covers and takes into account situations in which
the diameters and/or material properties of chilled rolls and/or polymer rolls are
changed.
[0064] As regards the process conditions of calendering, it can be stated generally that
they are determined by the capacities of the components that are used as rolls, as
is also ordinary in calender technology. Further, restrictive factors in the process
include the desired properties of paper, such as bulk (stiffness), smoothness/roughness,
and gloss, in particular gloss of printing paper. As examples of process conditions,
the US Patents 4,749,445 and 4,624,744 of S.D. Warre can be stated. A possible range
of surface temperature of a heatable, so-called thermo roll is T
_{s} = 60 °C ... 250 °C, depending on the running speed so that the surface temperature
is lower at low running speeds and higher at high running speeds, because the time
of effect of the nip is shorter and, thus, the transfer of heat from the thermo roll
to the web face is lower. The range of variation of linear load can be 20 kN/m ...
550 kN/m or even higher, again depending on the running speed and on the properties
of the variable-crown upper and lower rolls that produce the linear load in the supercalender.
[0065] Above, the invention has been described by way of example with reference to the figures
in the accompanying drawing. The invention is, however, not confined to the exemplifying
embodiments shown in the figures only, but different embodiments of the invention
may show variation within the scope of the inventive idea defined in the accompanying
patent claims.
[0066] The invention concerns a method and an arrangement for computing and regulation of
the distribution of linear load in a multi-nip calender. The material web (W) is passed
through the nips (N1...N9) in the set of rolls (12), which set of rolls comprises
a variable-crown upper roll (13), a variable-crown lower roll (14) and intermediate
rolls (15...22) fitted between the upper and lower rolls (13, 14). All the rolls in
the set of rolls are supported so that, when the nips (N1...N9) are closed, the bending
lines of the rolls are curved downwards. In the computing and regulation of linear
loads, the physical properties affecting the bending of each intermediate roll (15...22)
under load, such as bending rigidity, mass, shape, and material properties, are taken
into account. The ratio of the linear loads applied to the intermediate rolls (15...22),
the own weight of the rolls, and of the support forces applied to the rolls is regulated
so that the set of rolls is in a state of equilibrium and in a predetermined state
of deflection. The invention also concerns a multi-nip calender that carries out the
method.
1. A method of controlling a multi-nip calender including computing and regulation of
the distribution of linear load, wherein in the multi-nip calender the material web
(W) to be calendered is passed through the nips (N_{1}...N_{9}) in a set of rolls (12), which set of rolls is formed by a variable-crown upper roll
(13), a variable-crown lower roll (14) and by at least two intermediate rolls (15...22)
provided with support cylinders (154) and fitted between the upper and lower rolls
(13, 14), in which connection all the rolls in the set of rolls are supported so that,
when the nips (N_{1}...N_{9}) are closed, the bending lines of the rolls are curved downwards, characterized in that in the computing and regulation of linear loads, the physical properties affecting
the bending of each intermediate roll (15...22) under load, such as bending rigidity,
mass, shape, and material properties, are taken into account, and the ratio of the
linear loads applied to the intermediate rolls (15...22), of the own weight of the
rolls, and of the support forces applied to the rolls is regulated so that the set
of rolls is in a state of equilibrium and in a predetermined state of deflection,
comprising computerized modeling of all essential elements of the multi-nip calender
including determining the physical properties of all rolls and selecting the type
and position of each roll in the multi-nip calender,
determining of regulation parameters based on the computerized modeling,
regulating of the multi-nip calender assembled with the types and positions of rolls
used in the computerized modeling based on the computerized modeling.
2. A method as claimed in claim 1, characterized in that, in the method, in the set of rolls (12) in the calender, intermediate rolls (15...22)
are employed whose deflection properties are different from roll to roll.
3. A method as claimed in claim 1 or 2, characterized in that, in the computing, the set of rolls (12) is treated as a single unit.
4. A method as claimed in claim 1 or 2, characterized in that the computing is carried out by a pair of rolls (200).
5. A method as claimed in any of the preceding claims, characterized in that, in the method, the intermediate rolls (15...22) in the set of rolls (12) are supported
on the frame (11) of the calender so that the rolls are freely moving.
6. An arrangement for computing and regulation of the distribution of linear load in
a multi-nip calender meant for calendering of paper or board, which calender comprises
a set of rolls (12) which is mounted on the frame of the calender and which set of
rolls includes a variable-crown upper roll (13), a variable-crown lower roll (14)
as well as several intermediate rolls (15...22) fitted between the upper roll and
the lower roll, in which connection the means of suspension of the intermediate rolls
(15...22) are provided with support cylinders (154), and all the rolls in the set
of rolls are supported so that, when the nips (N_{1}...N_{9}) are closed, the bending lines of the rolls are curved downwards, characterized in that the arrangement includes an automation system (30) and a computing unit (40), which
have been fitted, in the computing and regulation of linear loads, to take into account
the physical properties affecting the bending of each intermediate roll (15...22)
under load, such as bending rigidity, mass, shape, and material properties, and to
regulate the ratio of the linear loads applied to the intermediate rolls (15...22),
of the own weight of the rolls, and of the support forces applied to the rolls so
that the set of rolls is in a state of equilibrium and in a predetermined state of
deflection,
wherein the computing unit (40) computerizes models of all essential elements of the
multi-nip calender including the determination of the physical properties of all rolls,
wherein the type and position of each roll in the multi-nip calender is selected,
the automation system (30) regulates the multi-nip calender based on the computerized
modeling assembled with the types and positions of rolls used in the computerized
modeling.
7. An arrangement as claimed in claim 6, characterized in that the arrangement has been arranged to regulate the set of rolls (12) in the calender,
in which the intermediate rolls (15...22) have deflection properties different from
roll to roll.
8. An arrangement as claimed in claim 6 or 7, characterized in that the arrangement has been fitted, in computing, to treat the set of rolls (12) as
a single unit.
9. An arrangement as claimed in claim 6 or 7, characterized in that the arrangement carries out the computing by a pair of rolls (200).
10. A multi-nip calender controlled by the method as claimed in any of the claims 1 to
5.
1. Verfahren zum Steuern eines Mehrspaltkalanders mit einem Berechnen und Regulieren
der Verteilung einer linearen Belastung, wobei bei dem Mehrspaltkalander die zu kalendrierende
Materialbahn (W) durch die Spalte (N_{1}...N_{9}) in einem Satz an Walzen (12) tritt, wobei dieser Satz an Walzen ausgebildet ist
durch eine obere Walze (13) mit variabler Bombierung, eine untere Walze (14) mit variabler
Bombierung und durch zumindest zwei Zwischenwalzen (15...22), die mit Stützzylindern
(154) versehen sind und die zwischen der oberen und der unteren Walze (13, 14) sitzen,
wobei in diesem Zusammenhang sämtliche Walzen bei dem Satz an Walzen so gestützt sind,
dass, wenn die Spalte (N_{1}.. N_{9}) geschlossen sind, die Biegelinien der Walzen nach unten gekrümmt sind,
dadurch gekennzeichnet, dass
bei dem Berechnen und Regulieren der linearen Belastungen die das Biegen von jeder
Zwischenwalze (15...22) unter der Belastung beeinflussenden physikalischen Eigenschaften,
wie beispielsweise die Biegesteifigkeit, die Masse, die Form und Materialeigenschaften,
berücksichtigt werden und das Verhältnis der auf die Zwischenwalzen (15...22) aufgebrachten
linearen Belastungen, des Eigengewichtes der Walzen und der Stützkräfte, die auf die
Walzen aufgebracht werden, so reguliert wird, dass der Satz an Walzen in einem Gleichgewichtszustand
ist und in einem vorbestimmten Durchbiegungszustand ist,
mit einem per Computer erfolgenden Modellieren von sämtlichen wesentlichen Elementen
des Mehrspaltkalanders mit einem Bestimmen der physikalischen Eigenschaften sämtlicher
Walzen und Auswählen der Art und Position von jeder Walze bei dem Mehrspaltkalander,
Bestimmen der Regulierparameter auf der Grundlage des per Computer erfolgenden Modellierens,
Regulieren des Mehrspaltkalanders, der mit den Arten und Positionen der Walzen zusammengebaut
ist, die bei dem per Computer erfolgenden Modellieren verwendet werden, auf der Grundlage
des per Computer erfolgenden Modellierens.
2. Verfahren gemäß Anspruch 1,
dadurch gekennzeichnet, dass
bei diesem Verfahren bei dem Satz an Walzen (12) bei dem Kalander Zwischenwalzen (15...22)
angewendet werden, deren Durchbiegungseigenschaften von Walze zu Walze unterschiedlich
sind.
3. Verfahren gemäß Anspruch 1 oder 2,
dadurch gekennzeichnet, dass
bei dem Berechnen der Satz an Walzen (12) als eine einzelne Einheit behandelt wird.
4. Verfahren gemäß Anspruch 1 oder 2,
dadurch gekennzeichnet, dass
das Berechnen durch ein Paar an Walzen (200) ausgeführt wird.
5. Verfahren gemäß einem der vorherigen Ansprüche,
dadurch gekennzeichnet, dass
bei diesem Verfahren die Zwischenwalzen (15...22) bei dem Satz an Walzen (12) an dem
Rahmen (11) des Kalanders so gestützt sind, dass die Walzen sich frei bewegen können.
6. Vorrichtung für ein Berechnen und Regulieren der Verteilung einer linearen Belastung
bei einem Mehrspaltkalander, der für ein Kalendrieren von Papier oder Karton gedacht
ist, wobei der Kalander folgendes aufweist: einen Satz an Walzen (12), der an dem
Rahmen des Kalanders montiert ist und wobei der Satz an Walzen eine obere Walze (13)
mit variabler Bombierung, eine untere Walze (14) mit variabler Bombierung und auch
mehrere Zwischenwalzen (15...22) hat, die zwischen der oberen Walze und der unteren
Walze sitzen, wobei in diesem Zusammenhang die Einrichtungen zum Aufhängen der Zwischenwalzen
(15...22) mit Stützzylindern (154) versehen sind, und sämtliche Walzen bei dem Satz
an Walzen so gestützt sind, dass, wenn die Spalte (N_{1}...N_{9}) geschlossen sind, die Biegelinien der Walzen nach unten gekrümmt sind,
dadurch gekennzeichnet, dass
die Vorrichtung ein Automatisierungssystem (30) und eine Berechnungseinheit (40) hat,
die bei dem Berechnen und Regulieren der linearen Belastungen eingesetzt sind, um
die physikalischen Eigenschaften zu berücksichtigen, die das Biegen von jeder Zwischenwalze
(15...22) unter der Belastung beeinflussen, wie beispielsweise die Biegesteifigkeit,
die Masse, die Form und die Materialeigenschaften, und um das Verhältnis der linearen
Belastungen, die auf die Zwischenwalzen (15...22) aufgebracht werden, des Eigengewichtes
der Walzen und der Stützkräfte, die auf die Walzen aufgebracht werden, so zu regulieren,
dass der Satz an Walzen in einem Gleichgewichtszustand und in einem vorbestimmten
Durchbiegungszustand ist,
wobei die Berechnungseinheit (40) Modelle von sämtlichen wesentlichen Elementen des
Mehrspaltkalanders, wobei die Bestimmung der physikalischen Eigenschaften von sämtlichen
Walzen umfasst ist, berechnet, wobei die Art und die Position von jeder Walze bei
dem Mehrspaltkalander gewählt wird,
das Automatisierungssystem (30) den Mehrspaltkalander auf der Grundlage des per Computer
erfolgenden Modellierens reguliert, der mit den Arten und Positionen der Walzen zusammengesetzt
ist, die bei dem per Computer erfolgenden Modellieren verwendet werden.
7. Vorrichtung gemäß Anspruch 6,
dadurch gekennzeichnet, dass ,
die Vorrichtung so eingerichtet 1st, dass der Satz an Walzen (12) bei dem Kalander
reguliert wird, bei dem die Zwischenwalzen (15...22) Durchbiegungseigenschaften haben,
die sich von Walze zu Walze unterscheiden.
8. Vorrichtung gemäß Anspruch 6 oder 7,
dadurch gekennzeichnet, dass
die Vorrichtung beim Berechnen so eingesetzt wird, dass der Satz an Walzen (12) als
eine einzelne Einheit behandelt wird.
9. Vorrichtung gemäß Anspruch 6 oder 7,
dadurch gekennzeichnet, dass
die Vorrichtung das Berechnen durch ein Paar an Walzen (200) ausführt.
10. Mehrspaltkalander, der durch das Verfahren gemäß einem der Ansprüche 1 bis 5 gesteuert
wird.
1. Procédé pour commander une calandre multipince qui comprend le calcul et la régulation
de la distribution d'une charge linéaire, dans lequel, dans la calandre multipince,
la bande de matière (W) qu'il s'agit de calandrer est enfilée entre les pinces (N_{1}...N_{9}) d'un jeu de rouleaux (12), lequel jeu de rouleaux est formé par un rouleau supérieur
(13) à voussure variable, un rouleau inférieur (14) à voussure variable et par au
moins deux rouleaux intermédiaires (15...22) munis de vérins de support (154) et interposés
entre les rouleaux supérieur et inférieur (13, 14), dans lequel tous les rouleaux
du jeu de rouleaux sont supportés de manière que, lorsque les pinces (N_{1}....N_{9}) sont fermées, les lignes de flexion des rouleaux soient incurvées vers le bas, caractérisé en ce que, dans le calcul et la régulation des charges linéaires, les propriétés physiques
qui affectent la flexion de chaque rouleau intermédiaire (15...22) sous charge, telles
que la rigidité à la flexion, la masse, la forme et les propriétés des matières, sont
prises en compte et le rapport des charges linéaires appliquées aux rouleaux intermédiaires
(15...22), du poids propre des rouleaux et des forces de support appliquées aux rouleaux,
est régulé de manière que le jeu de rouleaux se trouve dans un état d'équilibre et
dans un état de flexion prédéterminé,
comprenant une modélisation informatisée de tous les éléments essentiels de la calandre
multipince, y compris la détermination des propriétés physiques de tous les rouleaux
et la sélection du type et de la position de chaque rouleau de la calandre multipince,
la détermination de paramètres de régulation basée sur la xnodélisation informatisée,
la régulation sur la base de la modélisation informatisée, de la calandre multipince
assemblée avec les types et positions des rouleaux utilisés dans la modélisation informatisée.
2. Procédé selon la revendication 1, caractérisé en ce que, dans le procédé, dans le jeu de rouleaux (12) de la calandre, on utilise des rouleaux
intermédiaires (15...22) dont les propriétés de flexion sont différentes d'un rouleau
à l'autre.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que, dans le calcul, le jeu de rouleaux (12) est traité comme une seule unité.
4. Procédé selon la revendication 1 ou 2, caractérisé en ce que le calcul est exécuté par une paire de rouleaux (200).
5. Procédé selon une quelconque des revendications précédentes, caractérisé en ce que, dans le procédé, les rouleaux intermédiaires (15...22) du jeu de rouleaux (12) sont
appuyés sur le bâti (11) de la calandre de telle manière que les rouleaux soient librement
mobiles.
6. Dispositif pour calculer et réguler la distribution de la charge linéaire dans une
calandre multipinces conçue pour calandrer du papier ou du carton, laquelle calandre
comprend un jeu de rouleaux (12) qui est monté sur le bâti de la calandre et lequel
jeu de rouleaux comprend un rouleau supérieur (13) à voussure variable, un rouleau
inférieur (14) à voussure variable, ainsi que plusieurs rouleaux intermédiaires (15...22)
interposés entre le rouleau supérieur et le rouleau inférieur, dans lequel les moyens
de suspension des rouleaux intermédiaires (15...22) sont équipés de vérins de support
(154) et tous les rouleaux du jeu de rouleaux sont supportés de telle manière que,
lorsque les pinces (N_{1}...N_{9}) sont fermées, les lignes de flexion des rouleaux soient incurvées vers le bas, caractérisé en ce que le dispositif comprend un système d'automation (30) et une unité de calcul (40) qui
ont été prévus pour prendre en compte, dans le calcul et la régulation des charges
linéaires, les propriétés physiques qui affectent la flexion de chaque rouleau intermédiaire
(15...22) sous charge, telles que la rigidité à la flexion, la masse, la forme et
les propriétés des matières, et pour réguler le rapport des charges linéaires appliquées
aux rouleaux intermédiaires (15...22), du poids propre des rouleaux et des forces
de support appliquées aux rouleaux de manière que le jeu de rouleaux se trouve dans
un état d'équilibre et dans un état de flexion prédéterminé,
dans lequel l'unité de calcul (40) effectue la modélisation informatisée de tous les
éléments essentiels de la calandre multipince, y compris la détermination des propriétés
physiques de tous les rouleaux, dans lequel le type et la position de chaque rouleau
dans la calandre multipince sont sélectionnés,
le système d'automation (30) régule la calandre multipince sur la base de la modélisation
informatisée assemblée avec les types et les positions de rouleaux utilisés dans la
modélisation informatisée.
7. Dispositif selon la revendication 6, caractérisé en ce que le dispositif a été agencé pour réguler le jeu de rouleaux (12) de la calandre, dans
lequel les rouleaux intermédiaires (15...22) possèdent des propriétés de flexion différentes
d'un rouleau à l'autre.
8. Dispositif selon la revendication 6 ou 7, caractérisé en ce que le dispositif a été prévu pour traiter le jeu de rouleaux (12) comme une seule unité
dans le calcul.
9. Dispositif selon la revendication 6 ou 7, caractérisé en ce que le dispositif exécute le calcul par une paire de rouleaux (200).
10. Calandre multipince commandée par le procédé selon une quelconque des revendications
1 à 5.