U.S. patent number 3,799,052 [Application Number 05/326,773] was granted by the patent office on 1974-03-26 for apparatus for the continuous pressure treatment of a web.
This patent grant is currently assigned to SAID Kusters, by said Appenzeller. Invention is credited to Valentin Appenzeller, Eduard Kusters.
United States Patent |
3,799,052 |
Kusters , et al. |
March 26, 1974 |
APPARATUS FOR THE CONTINUOUS PRESSURE TREATMENT OF A WEB
Abstract
The apparatus includes a drum and a pressure belt surrounding
the drum almost completely with both drum and pressure belt being
movable with the web disposed inbetween. A sleeve is disposed about
the pressure belt as a supporting surface with a friction-reducing
means, such as interconnected rollers, between the sleeve and
pressure belt to transfer force. The sleeve ends are spaced apart
to permit passage of the web and pressure belt while at the same
time being urged together to impart a tensile force in the sleeve.
This tensile force serves to exert a uniform pressure on the moving
web substantially over the entire surface of the drum, which may be
heated.
Inventors: |
Kusters; Eduard
(Krefeld-Forstwald, DT), Appenzeller; Valentin
(Kempen/Ndrh., DT) |
Assignee: |
SAID Kusters, by said
Appenzeller (N/A)
|
Family
ID: |
5835140 |
Appl.
No.: |
05/326,773 |
Filed: |
January 26, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
100/313; 34/123;
100/154; 162/206; 100/334; 34/118; 100/153; 162/205; 162/305 |
Current CPC
Class: |
B30B
5/04 (20130101); D06C 15/06 (20130101); D21G
1/006 (20130101) |
Current International
Class: |
B30B
5/00 (20060101); B30B 5/04 (20060101); D06C
15/06 (20060101); D06C 15/00 (20060101); D21G
1/00 (20060101); D21g 001/00 (); D21f 005/02 ();
F26b 013/18 () |
Field of
Search: |
;162/205,206,358,305,210
;100/151,152,153,154,121,93RP ;34/111,116,117,118,123 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
923,172 |
|
Jul 1955 |
|
DT |
|
525,788 |
|
Feb 1954 |
|
BE |
|
Primary Examiner: Bashore; S. Leon
Assistant Examiner: Tushin; Richard H.
Attorney, Agent or Firm: Kenyon & Kenyon Reilly Carr
& Chapin
Claims
What is claimed is:
1. An apparatus for the continuous pressure treatment of a web
comprising
a rotatable drum having a surface for engaging the web;
a movable pressure belt looped about said drum for concurrent
movement therewith with the web disposed between said drum and said
belt;
a sleeve forming a supporting surface about said belt, said sleeve
being disposed around said drum surface for substantially more than
180.degree. with a pair of opposed ends in spaced apart relation
for passage of said belt therebetween;
friction-reducing means between said sleeve and said belt; and
means interconnecting said ends of said sleeve to impart a tensile
stress in said sleeve.
2. An apparatus as set forth in claim 1 wherein said
friction-reducing means includes a plurality of rolling members
rollably disposed between said sleeve and said belt.
3. An apparatus as set forth in claim 1 wherein said sleeve is a
bent steel plate.
4. An apparatus as set forth in claim 1 which further comprises
means for guiding said belt around said drum in the shape of a
meander having a narrow neck and wherein said ends of said sleeve
extend into the vicinity of said neck.
5. An apparatus as set forth in claim 1 wherein said means
interconnecting said sleeve ends includes controllable force
elements for exerting a tensile stress on said sleeve ends.
6. An apparatus as set forth in claim 5 wherein said elements are
disposed outside of the width of the web.
7. An apparatus as set forth in claim 6 wherein said elements are
directly connected with said sleeve ends.
8. An apparatus as set forth in claim 6 wherein said means
interconnecting said sleeve ends further includes a pair of
transverse yokes, each yoke being disposed along said neck across
the width of the web and connected to said controllable force
elements, and a plurality of force transmitting members connecting
each yoke to said sleeve over the width of said sleeve.
9. An apparatus as set forth in claim 5 further comprising a
bearing journalling said drum therein, and a support mounted on
said bearing in the plane of said neck with a pair of said
controllable force elements connected to opposite ends of said
sleeve bearing on said support.
10. An apparatus as set forth in claim 9 wherein each controllable
force element is independently connected to said support relative
to an opposed controllable force element.
11. An apparatus as set forth in claim 5 further comprising a
bearing journalling said drum therein and a support mounted on said
bearing in the plane of said neck, wherein said means
interconnecting said sleeve ends includes a pair of tensioning
elements on each side of the web connected to said ends and to a
common point with said force controllable element connected between
said point and said support to displace said point away from said
bearing.
12. An apparatus as set forth in claim 1 wherein said pressure belt
is a steel belt and which further comprises an additional belt
movably mounted between said steel belt and said drum.
13. An apparatus as set forth in claim 12 wherein the web is
disposed to run between said additional belt and said drum.
14. An apparatus as set forth in claim 12 wherein the web is
disposed to run between said additional belt and said pressure
belt.
15. An apparatus as set forth in claim 12 wherein said additional
belt is made of polyamide.
16. An apparatus as set forth in claim 12 including means for
driving said drum and means for driving said belts at different
peripheral speeds.
17. An apparatus as set forth in claim 1 wherein said pressure belt
and said friction-reducing means run on endless paths extending
around the outside of said drum.
18. An apparatus as set forth in claim 17 wherein said
friction-reducing means includes rolling members in the form of a
large number of endless roller chains advancing closely adjacent to
one another.
19. An apparatus as set forth in claim 1 further including means
for heating at least one of said drum and said sleeve.
20. An apparatus as set forth in claim 1 including means for
driving said drum and means for driving said pressure belt at
different peripheral speeds.
Description
FIELD OF THE INVENTION
This invention relates to an apparatus for the continuous pressure
treatment of a web, and particularly to the continuous pressure
treatment of webs of paper, textiles and the like.
DESCRIPTION OF THE PRIOR ART
Heretofore, in the continuous pressure treatment of moving webs it
has been known to use pairs of rollers to compress the web as the
web passes through the nip formed by each roller pair. Thus, the
zone of action of the pressure is only the narrow roller nip, which
in theory is merely a line but in practice, due to the thickness
and compressibility of the material and the deformation of the
roller surface, is a narrow zone. To enable treatment to be
performed adequately, therefore, the treatment must often be
repeated. Thus, the web has been guided through a number of
successive roller nips, one after the other. This is done in known
manner, for instance, in a paper calendar which normally comprises
stacks of up to 12 superimposed rollers over which the paper web is
guided, being looped alternately over the successive rollers. The
required pressure treatment is performed between each pair of
rollers, and the total operative surface is the sum of the narrow
pressure zones of the individual roller nips. However, this
involves a considerable expense due to the large number of rollers
needed to obtain the operative surface, a large roller stand and
many drives.
In order to overcome the disadvantages of these systems, it has
been known to use an apparatus for the continuous pressure
treatment of webs in which the pressure is operative over a larger
area than with rollers, without the expense of providing a large
number of rollers connected one after the other. The basic concept
of this apparatus is to extend the working nip, in which pressure
is exerted between two rollers, over the surface of one roller or
drum thus increasing the operative surface. To this end, the
operative surface is increased by substituting a concurrently
movable forming belt for the matching roller and by partly looping
the forming belt around the drum. The web is guided between the
co-rotating forming belt and drum and is pressure-treated
therebetween.
In this latter apparatus, the pressure which can be exerted on a
web corresponds to the pressure under which the forming belt bears
against the drum, and is determined by the tensioning of the
forming belt. Such tensioning is usually subjected to fairly
precisely defined limits. The forming belt is, of course, endless
and must be deflected several times over rollers or drums in its
path. The resulting bending causes tensile and compressive stresses
in the material of the forming belt which must remain in the
resilient zone, i.e., below the flow limit of the material of the
belt. Since the drum radii cannot be increased as required to
improve the bending geometry, with any particular construction
there is a maximum permissible belt thickness, from which the limit
of the permissible tensile loading of the belt is determined. The
resulting radial pressures are, however, inadequate to produce on a
web, for instance, an effect comparable with the work of a
calender.
German Pat. Specification No. 923,172 discloses an apparatus for
continuous pressing which includes a rotating drum having a steel
forming belt looped around the surface by about 120.degree., the
material to be pressed being disposed between the forming belt and
the drum. In addition, a segment which has a supporting surface
adapted to the outer shape of the forming belt is disposed outside
of the forming belt and is pressed radially against the drum. Also,
rolling members which transmit pressure from the supporting surface
to the forming belt are rollably disposed between the steel belt
and the supporting surface. When pressure is exerted in this way,
there is no need for special belt tensioning, which is difficult to
control.
However, the radial application of pressure by the supporting
surface causes radial forces on the drum which must be absorbed by
the drum bearing. Consequently, in the case of an apparatus for
processing fairly wide webs such as, for instance, webs of paper,
and also, if the zone of application of pressure is to be widened
in the peripheral direction, bearing loadings can cause
considerable technical problems. The expense of the apparatus would
also be increased if attempts are made to attain pressures
comparable with arrangements of rollers.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an
apparatus for the continuous pressure treatment of webs in which
the pressure is operative over a large area without the expense of
providing a large number of rollers connected one after the
other.
It is another object of the invention to provide an apparatus for
the continuous pressure treatment of webs using a drum in which a
substantial circumferential portion of the drum is used for the
treatment.
It is another object of the invention to decrease the bearing load
on a drum bearing wherein a web is continuously pressed against the
drum surface by a concurrently moving pressure belt.
Briefly, the invention provides an apparatus for the continuous
pressure treatment of a web comprising a rotatable drum, a movable
pressure belt looped about the drum and a sleeve forming a
supporting surface about the belt. The sleeve is disposed about the
drum surface for substantially more than 180.degree. with a pair of
opposed ends in spaced apart relation to form an axial nip for
passage of the belt. In addition, friction-reducing means are
provided between the sleeve and belt and means are interconnected
to the ends of the sleeve to impart a tensile stress in the
sleeve.
The sleeve is looped around the drum by more than 180.degree. to
terminate in a zone in which the ends of the sleeve approach one
another after being looped around the drum. As a result of this and
the tensile force existing between the ends of the sleeve, the
sleeve can act like a tensioning belt whose tensioning in the
peripheral direction exerts a radial force on the pressure belt and
the drum. The force corresponds to the pressure exerted on the web.
Whereas, in the prior art arrangement, the force was directed from
the supporting surface one sidedly against the drum, now, at least,
a proportion of the force is left inside the sleeve and kept away
from the drum bearing.
If the sleeve were only looped about the drum for 180.degree., the
forces exerted on the drum in the supposed 180.degree. portion of
the sleeve would produce a resultant force representing a very
considerable force on the drum bearing. However, by looping the
sleeve around the drum by more than 180.degree., the zones of the
sleeve acting on the drum outside the 180.degree. portion create
forces which reduce the aforementioned resultant, since they partly
cancel out the first-mentioned forces. However, the distribution of
force is not completely uniform, since a gap for the entry and exit
of the web and the concurrently moving pressure belt has to be left
at one place in the sleeve.
Although the resulting bearing forces are reduced by the supporting
surface being constructed in the form of a sleeve, the working
surface is extended over almost the whole drum periphery.
The sleeve can take the form of a steel plate bent around the drum.
For instance, the sleeve can be a plate about 6 to 12 millimeters
(mm) in thickness which is pre-shaped to match the drum shape. In
contrast with the pressure belt, which is constantly deflected and
bent backwards and forwards, during operation, the sleeve is only
slightly deformed. There is therefore the required freedom in the
dimensions of the sleeve whereas the pressure belt which is
relieved from the job of applying force, can have the thin wall
necessary to reduce the bending stresses.
Conveniently, to make full use of the tensioning-bolt-like effect
of the sleeve, the pressure belt is guided around the drum, in
known manner, in the shape of a meander having a narrow neck, and
the ends of the sleeve extend as far as the vicinity of the neck.
In this way, the sleeve engages around almost the whole drum and
the gap for the entry and exit of the web and pressure belt is as
narrow as possible.
Conveniently, controllable force elements are provided which exert
the tensile stress on the ends of the sleeve. This feature enables
the required working pressure to be adjusted in the same way as the
setting of a pair of rollers is altered.
In a preferred embodiment of the invention, the tensile stress
operative on the ends of the sleeve is transmitted via tensioning
elements disposed outside the web width. The web and pressure belt
can thus enter between the sleeve and the drum in the space between
the tensioning elements.
In another embodiment, the tensioning elements engage directly with
the ends of the sleeve. This feature is, of course, on condition
that the sleeve ends are suitably reinforced so as not to be
deformed by the forces operative only on both sides.
Alternatively, the tensioning elements can engage with transverse
yokes which are disposed in the vicinity of the meander neck,
outside the neck and inside the pressure belt, and which extend
transversely over the web width. In this case, force-transmitting
members are distributed over the web width and engage with the ends
of the sleeve and the yokes. In this way, the tensioning force can
operate at a number of places on the sleeve edge distributed over
the width of the web, and the uniformity of the force exerted no
longer depends on the transverse-breaking strength of such edge.
The transverse yokes can readily be made very rigid, so as to
absorb the high bending forces.
In another embodiment of the invention, a support bearing against
the rotary bearing of the drum is disposed in the zone of the
meander neck, and tensioning members engaging with the support are
disposed at both ends of the sleeve. The sleeve ends are not
directly interconnected, but are connected via the support. In
operation, the support deflects the forces resulting from the fact
that the sleeve is not completely looped around the drum to the
drum bearing.
In another embodiment of the invention, the tensioning members
associated with the two ends of the sleeve can exert a tensioning
force independently of one another between that particular end of
the sleeve and the fixed support. The independent exertion of force
is advantageous since it allows, by suitable adjustment,
compensation for the forces transmitted peripherally by the
rotating drum to the sleeve. Thus, some of the tensioning members
can be adjusted for stronger tensioning oppositely to the
peripheral force than others of the members.
In another embodiment, a force member is provided which can move
the place of engagement of the tensioning elements with the support
away from the drum bearing. In this case, the tensioning elements
can take the form of rigid anchors, only one force-exerting device
being needed on each side.
The pressure belt can be basically made of any suitable material,
for instance, even plastics or the like. In one embodiment of the
invention the pressure belt takes the form of a steel belt while a
second movable belt is provided between the steel belt and the
drum. This enables the web to be pressed between belts of different
kinds, depending on the treatment required. The web can extend
between the second belt and the drum, or between the second belt
and the pressure belt. When the treatment calls for this, the
second belt is made of a material having a different surface
texture from steel. In that case, the steel surface acts on the web
on one side, and the special surface on the other. For treating
paper, for instance, polyamide has proved very advantageous and can
therefore be the material of which the second belt is made.
According to the invention, the forces between the sleeve and the
pressure belt are transmitted by friction reducing means in the
form of rolling members rolling therebetween which reduce friction
when the pressure belt leads on the sleeve. Conveniently, the
pressure belt and the rolling members run on endless tracks which
extend around the outside of the drum.
In a preferred embodiment of the invention, the rolling members
take the form of a large number of endless roller chains which are
constructed to advance closely adjacent to one another. These
roller chains are so constructed as to leave behind no zones of the
belt over which they have not rolled, but to roll over the whole
belt surface. The roller diameter is selected according to
circumstances.
It is not absolutely necessary for the rollers to follow closely
one behind the other in order to prevent the forming belt from
sagging noticeably between the rollers. The pressure belt can
become slightly corrugated. In that case, a roller-nip-like
situation occurs at each roller for the web trapped between the
pressure belt and the drum and the result as a whole is a treatment
effect corresponding to the web passing through a succession of the
same number of pairs of rollers. For the rest, however, the roller
diameter is determined in accordance with the required working
speed. For a higher working speed, larger roller diameters are
convenient to keep the speed of rotation down.
Use must be made of pressure and temperatures simultaneously in
many treatments of paper, textile and similar webs. For this
purpose, the drum can be heated either electrically or by
steam.
Moreover, in the pressure treatment of a web of material, the two
pressure surfaces working against one another must often perform a
relative movement in relation to one another to produce a so-called
frictional effect. This is usually done, for instance, in friction
calenders to make paper glossy or produce a chintz effect in
textiles.
Conveniently, in order to produce a friction effect of this kind in
the apparatus according to the invention, the drum and the pressure
belt or the drum and the second belt or the second belt and the
pressure belt can each be driven at different peripheral speeds.
Which of these possibilities is adopted in each individual case
depends on the guiding of the web. That is, those surfaces which
enclose the web of materials between them must be given different
peripheral speeds.
These and other objects and advantages of the invention will become
more apparent from the following detailed description and appended
claims taken in conjunction with the accompanying drawings in
which:
DESCRIPTION OF THE DRAWINGS
FIG. 1 diagrammatically illustrates a side view of an apparatus
according to the invention utilizing one tension element at each
side of the drum for tensioning a sleeve;
FIG. 2 diagrammatically illustrates a side view of a modified
apparatus according to the invention utilizing a pair of tension
elements at each side of the drum for tensioning a sleeve;
FIG. 3 diagrammatically illustrates a view of a tensioning element
according to the invention which cooperates with a support to
relieve a drum bearing of load;
FIG. 4 diagrammatically illustrates a view of a tensioning element
interconnected with longitudinally disposed yokes on opposite sides
of the sleeve in accordance with the invention;
FIGS. 5, 6 and 7 each illustrate a plan view of a different roller
chain for use with an apparatus according to the invention;
FIG. 8 illustrates a side view of an apparatus in which the web
runs between the drum and a plastic belt; and
FIG. 9 illustrates a side view of an apparatus in which the web
runs between a plastic belt and a pressure belt.
DETAILED DESCRIPTION
Referring to FIG. 1, a web 1 runs in meander shape around a drum 2
which rotates around a shaft 3 in the directon indicated by arrow
4. A pressure belt 5 co-rotates, i.e., moves concurrently with the
drum 2, on the outside of the web 1. The belt 5 is looped over a
large portion of the periphery of the drum 2 so that the web 1 is
trapped between the pressure belt 1 and the drum surface. A sleeve
6 is disposed outside of the pressure belt 5 to also enclose the
drum 2 over a large part of the drum periphery, for example, over
180.degree.. To this end, the sleeve 6 is sized to extend to the
vicinity of the neck 7 of the meander-shaped course of the pressure
belt 5 to leave a gap 8 through which the web 1 and the pressure
belt 5 can enter and exit between the sleeve 6 and the drum
surface.
The sleeve 6 is stationary in relation to the rotating drum 4 and
corotating pressure belt 5. In order to reduce the friction
occurring between the pressure belt 5 and the sleeve 6,
friction-reducing means such as roller chains 9 are provided which
roll between the outside of the pressure belt 5 and the inside of
the sleeve 6. These roller chains 9 form a supporting surface when
the pressure belt 5 rotates or moves about the drum axis. The
roller chains 9 are disposed close, one beside the other, over a
width of the web and allow a rolling transmission of pressure over
the whole supporting surface of the sleeve 6.
The ends 6', 6" of the sleeve 6 are interconnected via a means for
imparting tensile stress in the sleeve 6. As shown, these means are
tensioning elements 10 provided outside the web 1 on both sides of
the web. The tensioning elements 10 each pull the ends 6', 6" of
the sleeve 6 towards one another so that the sleeve 6 acts as a
tensioning belt and exerts a radial pressure on the roller chains 9
which, in turn, transmit the pressure to the pressure belt 5 and
the web 1. Although the sleeve 6 is stable, but not completely
rigid, the radial pressure produced by the peripheral pulling of
the sleeve is distributed substantially uniformly over the
periphery of the drum 2. The sleeve 6 can be made, for instance,
from steel plate about 6 to 12 millimeters (mm) thickness.
Referring to FIG. 2, wherein like reference characters indicate
like parts as above, the ends 6', 6" of the sleeve 6 are not
interconnected directly, but via tensioning members 11, 12 which
are associated with each end 6', 6". These tensioning members 11,
12 are disposed on both sides of the web width and engage with a
support 13 bearing against the drum bearing (not shown). The
support 13 serves to absorb the forces produced by the angular
position of the vectors of force of the tensioning members 11, 12.
The vectors of force of the tensioning members 11, 12 correspond to
the plane of the tangent to the drum 2 at the level of the ends 6',
6" of the sleeve 6. The higher the ends 6', 6" are pulled up onto
the drum, i.e., the nearer the approach to one another, the flatter
will be the tangents and, therefore, the lower the resulting force
to be absorbed by the support 13 and, more particularly, by its
bearing on the drumshaft 3.
Referring to FIG. 3, wherein like reference characters indicate
like parts as above, instead of associating a tensioning member
with each end 6', 6" of the sleeve 6 on each side, the support 13
is provided with a force member 14 while the sleeve ends 6', 6" are
connected together via anchors 16, 17 which extend from a common
point 15. The anchors 16, 17 are also connected to the support 13
at this point 15. The force member 14 is constructed to urge the
point 15 upwardly, i.e., away from the shaft 3 of the drum 2. This
also produces a tensile force between the ends 6', 6" to create the
required tensioning. The force or power member 14 can be a pressure
generator. Alternatively, in order to produce the same effect, a
tension generator might also be provided on the support 13 above
the point 15.
Referring to FIG. 4, wherein like reference characters indicate
like parts as above, the means for imparting the tensile stress in
the sleeve 6 includes two tensioning members 10 and two transverse
yokes 18 in the form of I-beams which extend over the width of the
web. Each tensioning member 10 is located to one side of the web 1
and is connected at opposite ends to a respective yoke 18. In
addition, a plurality of force transmitting members 19 are
distributed over the width of the web and are connected to the ends
6', 6" of the sleeve 6 and to the respective yokes 18. The members
19 serve to transfer the force of the tensioning member 10 from the
yokes 18 to the sleeve 6. The transverse yokes 18 absorb the
bending stresses produced by the fact that the tensioning members
10 are only laterally anchored. To compensate for the different
forces produced by bending, the force transmitting members 19 take
the form of hydraulic force members which are hydraulically
interconnected.
The force members 10, 11, 12, 14 described above can be of any
nature. Spindles, hydraulic cylinders or the like can be used.
Since the working parts of the force members are small, it is more
particularly recommended to use hydraulic units of large surfaces
operating with diaphragm-like pressure cushions.
Referring to FIG. 5, the roller chain 9 comprises two rollers 20,
21 per link of different lengths disposed one beside the other.
These rollers 20, 21 are also disposed alternately in successive
links and are interconnected by bent straps 22. The rollers 20, 21
are mounted overhung and form aligned end faces, so that adjacent
roller chains can be disposed directly one beside the other without
leaving a gap. The rollers 20, 21 cover all places in the chain
width, due to the offset arrangement of the gap between the rollers
20, 21 of each link.
Referring to FIG. 6, the roller chain 9 can alternatively be
constructed with three rollers 23-25 per link disposed one beside
the other and having different lengths in successive links. The
successive links are connected by straight straps, but for a number
of successive links, the straps are disposed offset towards the
same side. As a result, the straps extend as a whole in zig-zag
shape inside a chain, and therefore a roller constantly rolls over
each place in the chain width.
Referring to FIG. 7, the roller chain 9 can also be constructed
substantially as shown in FIG. 6 but with straps that do not extend
in zig-zag fashion. In this case, the straps always extend in the
direction of the same side, the straps being discontinued when they
approach a certain distance from the chain edge and being restarted
on the opposite side of the chain.
A plurality of the chains illustrated in FIGS. 5 to 7 run directly
one beside the other, but independently of one another, so that
there are no difficulties with regards to tilting of the roller
axes.
Referring to FIG. 8, an embodiment the general construction of
which corresponds to FIG. 2 is shown in greater detail. In this
apparatus, a pair of drums or rollers 30 are provided to form the
neck 7 of the meander-shaped course of the web 1 and pressure belt
5 around the drum 2. In this embodiment, the roller chains 9
rolling between the pressure belt 5 and the sleeve 6 are guided in
a closed path around the outside of the drum 2 over rollers 31
disposed substantially in a square pattern. Similarly, the pressure
belt 5 is guided around the drum 2 over rollers 32 outside the
roller chain 9. A second belt 34 is also disposed between the
pressure belt 5 and the web 1 and is guided around the drum 2 over
rollers 33 outside the pressure belt 5. The roller chains 9, the
pressure belt 5 and the second belt 34 can be tensioned
independently of one another by tensioning devices whose function
is indicated by the arrows 35, 36 and 37. All the drums 30 to 33
have shafts extending parallel with shaft 3 of drum 2.
The second belt 34 is made of polyamide which has special
advantages, for instance, for the surface treatment of paper. Where
the web 1 is a paper web which is located between the polyamide
belt 34 and the surface of the drum 2, the pressure treatment of
the web can be boosted by heating the drum 2. The drive of the
polyamide belt 34 and pressure belt 5 can also be controlled to
produce a different speed in the polyamide belt 34 relative to the
surface of the drum 2 and, therefore, a frictional effect on the
web.
Referring to FIG. 9, wherein like reference characters indicate
like parts as above, instead of running the web 1 between the
second belt and the drum 2, the second belt 38 can be arranged in
such a way that the web 1 runs between the second belt 38 and the
pressure belt 5. In this case, the second belt 38, which may be of
a plastic material, runs over a single supporting roller 39
disposed above the nip of the meander. In this embodiment, a
suitable drive produces a difference in speed between the second
belt 38 and the pressure belt 5, which receive the web 1
therebetween to produce friction.
* * * * *