GUIDE SYSTEM, INCLUDING DRIVE, FOR A WEB FROM PAPER OR CARDBOARD

SYSTEME DE GUIDAGE, INCLUANT LE MECANISME D'ENTRAINEMENT, POUR BANDE DE PAPIER OU DE CARTON

English Abstract

ABSTRACT OF THE DISCLOSURE
In a drive for running a paper or cardboard web, a fix point
with a fixed speed of rotation is established by passing the web
at a large loop angle across at least one hollow roll that is
provided with cylinder surface bores which generate a vacuum.
The web is thereby very firmly coupled with the roll along its
loop angle, thus enabling an accurate adjustment of the speed of
rotation. This is further improved in that either two hollow
rolls or one hollow roll and an adjacent reversing roll with an
appropriately large diameter are coupled with each other through
a transmission. An appropriately large loop angle, by the web W,
needs to be provided across the rolls which are coupled by means
of the transmission. The drive is primarily contemplated in
coating systems for paper or cardboard webs.

Claims

WHAT IS CLAIMED IS:
1. A web guiding apparatus for a running web comprising:
a plurality of mutually parallel rolls over which a web
runs sequentially for generating a traction acting on said web
and for altering said web as to running direction, at
least one of the parallel rolls being configured as a hollow
cylinder having a outer cylinder surface and a plurality of
perforations distributed across the cylinder surface in suction
roll fashion, wherein at least one of the plurality of parallel
rolls is disposed adjacent the hollow cylinder roll and is
coupled to the hollow cylinder roll by a mechanical transmission
having a fixed year ratio, the hollow cylinder roll and said one cyl-
indrical roll being driven by a rotary drive having a
substantially constant speed of rotation, and wherein the web is
looped over the hollow cylinder roll so as to subtend a web loop
angle of at least 120°.
2. The web guiding apparatus of Claim 1, in which three
adjacent rolls of said plurality of parallel rolls are coupled by
a mechanical transmission having a fixed gear ratio, with one of
the three rolls being disposed intermediate the others, and at
least the intermediate roll being configured as a hollow cylinder
having a cylinder surface and a plurality of cylinder perforations
distributed across the cylinder surface in suction roll
fashion.
3. The web guiding apparatus of Claim 2, in which, viewed
in the running direction of the web, the first one of the rolls
coupled by the transmission has a diameter which is at most 20%
smaller than that of the intermediate roll.
4. The web guiding apparatus of Claim 2, in which, viewed
in the running direction of the web, the first two rolls coupled
by the transmission in the direction of web travel are configured

as a hollow cylinder having(a cylinder surface)and a plurality of
cylinder surface bores distributed across the cylinder surface in
suction roll fashion, the cylinder surface bores being configured
to generate a suction effect at the surface of the cylinder in
response to rotation of the roll.
5. The web guiding apparatus of Claim 1 in which said
hollow cylinder includes on the inside cylinder circumference
thereof a ribbing extending substantially in the axial direction
of the roll.
6. The web guiding apparatus of Claim 2 in which said
hollow cylinder includes on the inside cylinder circumference
thereof a ribbing extending substantially in the axial direction
of the roll.
7. The web guiding apparatus of Claim 3 in which said
hollow cylinder includes on the inside cylinder circumference
thereof a ribbing extending substantially in the axial direction
of the roll.
8. The web guiding apparatus of Claim 4 in which said
hollow cylinder includes on the inside cylinder circumference
thereof a ribbing extending substantially in the axial direction
of the roll.
9. The web guiding apparatus of Claim 1 in which the
cylinder surface bores have a diameter less than 10 mm.
10. The web guiding apparatus of Claim 2 in which the
cylinder surface bores have a diameter less than 10 mm.
11. The web guiding apparatus of Claim 3 in which the
cylinder surface bores have a diameter less than 10 mm.
12. The web guiding apparatus of Claim 4 in which the
cylinder surface bores have a diameter less than 10 mm.
13. The web guiding apparatus of Claim 5 in which the
cylinder surface bores have a diameter less than 10 mm.

14. The web guiding apparatus of Claim 1 in which the
cylinder surface bores have a diameter in the range of 3 mm to 6
mm.
15. The web guiding apparatus of Claim 2 in which the
cylinder surface bores have a diameter in the range of 3 mm to 6
mm.
15. The web guiding apparatus of Claim 3 in which the
cylinder surface bores have a diameter in the range of 3 mm to 6
mm.
17. The web guiding apparatus of Claim 4 in which the
cylinder surface bores have a diameter in the range of 3 mm to 6
mm.
18. The web guiding apparatus of Claim 5 in which the
cylinder surface bores have a diameter in the range of 3 mm to 6
mm.

Description

o
GUIDE SYSTEM INCLUDING DRIVE FOR A WEB
BACKGROUND OF THE INVEyTION
The invention concerns a guide system including a drive for
generating a traction for a web through a sequence of mutually
parallel rolls which establish the web traction and also the
running direction of the web. At least one of the rolls includes
a rotary drive with an essentially constant speed of rotation.
Coupling of very many rolls together through a belt drive,
where different speeds of rotation of the drying cylinders ar~
I brought about by different diameters of the pulleys, is
¦ previously known from the German Patent Disclosure No. 23 31 494.
Another arrangement, preferably for drying sections of a
paper machine, is previously known from the Swedish Patent
Document No. 364 087, where a coupling of adjacent press rolls
~ and reversing rolls is effected. An overrunning clutch ensures
that the speed of rotation of the reversing roll differs ~rom
that resulting from the speed of the belt that effects the
coupling.
The problem underlying the invention is to provide,
preferably in drying systems for a coating group within or
separate from paper machines, a guide system for a paper or
cardboard web including the drive for the rolls carrying the web.
SUMMARY OF THE INVENTION
This problem is solved through the drive devices of the
present invention. These drive devices are generally located
behind a drying setup used for drying the coated paper. But
other points along the web path in a drying group of a coating
system, or within a coating system as such, are also possible.
What the invention device achieves, in addition to a large
loop angle, is that a vacuum generated on a perforated cylinder

~:o~
surface of the driven roll, or also on the roll coupled with it
through a fixed gear ratio transmission, effects good adherance
of the paper web to the roll and thus an exact observance or
adjustment of the web speed at that point. It has been found
that with the present invention, without using an external
vacuum, the effect of a suction roll can be achieved, thus
obtaining a good adherence of the paper web to the respective
rolls. Slip between the cylinder surface of the roll and the web
is thereby avoided so that the web speed, based on the speed of
rotation of the roll coupled with the web, can be observed very
accurately. Additionally, this becomes increasingly possible
through the coupling by means of the mechanical transmission with
fixed gear ratio.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained hereafter with the aid of
embodiments illustrated in the drawing.
Figs. 1, 3 and 4 show schematically two different
embodiments in cross section; and
Fig. 2 shows an axial section of Fig. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. l and 2, a web guiding apparatus for
a web W of e.g paper includes reversing rolls 14 and 15, a
tension measuring roll 17, and a spreader roll 18. Hollow
rolls l and 2 each having perforations 38 in its cylinder
surface are provided to guide the web W with a large loop angle.
A hot air drying device 37 is provided for drying the web.
According to Fig. 2, the roll 1 is driven by a motor 31 via
a pinion 4, and the roll 2 is driven through gears 5, 6 and 7
engaged with pinion 4. The loop angle oP the web W on the rolls
1 and 2 is at least 120 while on the roll 2 it amounts to about
200.

The suction effect of the hollow rolls fashioned after
known suction rolls can be amplified through ribbing or blades 39
extending essentially parallel to the roll axis.
The vacuum generated in the rolls 1 and 2 on account of
their high speed of rotation (peripheral speed) results in a firm
adherence of the web to the cylinder surface of the rolls, giving
a coefficient of friction of about 0.2 at web speeds of more than
800 m/min. The coefficient of friction achieved thereby is
almost that given between a web and a felt. Naturally, as
already stated, the loop angle must be appropriately large.
Additionally, as illustrated, the reversing roll 14 can be
coupled with the hollow roll 1 through additional gears 8, 9 and
10. Obtained thereby, overall, is a so-called "fix point" that
establishes an exact web speed at this point.
As can be seen from Fig. 2, the gears 5-8 contained in the
case 33 are powered by way of the pinion 4 through the drive
motor 31 of the roli 1. The motor is coupled through flange
plates 32 and 30 with the pinion 4, and the latter by way of
flange plate 27 with the hollow roll 1 (not illustrated in Fig.
2; ~ee Fig. 1). Similarly, plates 28 and 29 serve to couple the
transmission gear 7 with the journal of the roll 2 that runs in
the bearing 26.
Illustrated in Fig. 3 is a variant where only one hollow
roll 1 is provided and the first reversing roll 3 in the
direction of web travel has a diameter which nearly equals that
of the hollow roll. A fix point of the web speed with an
outstanding effect is also obtained with this arrangement. In
the case of Fig. 3, unlike Fig. 1, the input pinion of a
transmission could also drive the gear 7' coupled with the
reversing roll 3 r provided the reversing roll 3 has a diameter
which is maximally 20% smaller than that of the hollow roll 1. A

0
preferred arrangement involves the center drive for the hollow
roll l driving both the preceding reversing roll 3 and the
following reversing roll 14, the latter by way of gQars 8', 9'
and lO' and coupling it with the central hollow roll 1.
Illustrated in Fig. 4 is the basic arrangement with a
coupling by belt drive. This belt 21 is a dual cogged belt
featuring teeth on both sides. The coupling of the hollow rolls
l' and 2' is effected here through the cogged belt pulleys 22
through 25.

Representative Drawing