Note: Descriptions are shown in the official language in which they were submitted.
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This invention is concerned with paper web handling rolls, of the
type wherein a paper web is temporarily held against a part of the
surface of the roll by means of a vacuum created within the roll.
In a number of paper web handling operations, for example
interfolding cut sheets to obtain a stack of products, such as paper
towels or facial tissues, and folding cut sheets such as paper table
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napkins, a folding roll is used. These rolls are generally
cylindrical, and rotate at the same speed as the paper web passing
over them, which is being cut and/or folded. The paper web is held
onto the roll for a short period of time by means of a combination of
an evacuated chamber within the roll, and a plurality of small holes
through the roll communicating with the vacuum chamber by way of a
narrow slot like aperture extending internally along the length of the
roll. As the roll rotates,; vacuum is applied through the holes to one
surface of the paper web, thus temporarily holding it onto the roll.
The level of vacuum~applied is controlled to be enough to hold the
paper web and yet is insufficient to cause marking or damage to the
web.
It is also neceseary to be able to control the period of time,
which is equivalent to an arc of the circle of rotation of the roll,
during which vacuum is applied to the paper web.
In the known vacuum rolls of this type, the vacuum feed is
connected to the chamber in the roll by means of a sleeve or shoe
which has an inner arcuate slot on a face which bears against the end
of the roll, which includes a cooperatingly placed bore communicating
with the vacuum chamber. For part of the cycle of rotation of the
roll the bore will be open to the arcuate slot, thus evacuating the
roll chamber, and for part of the cycle of rotation the bore will be
open to the atmosphere, thus releasing the vacuum. Examples of this
form of construction are to be found in U.S. 3,338,575; 3,489,406;
3,490,762; 4,778,441; 4,564,418; and 4,254,947.
Apart from the fact that such rolls are quite noisy in operation
(see U.S. 4,564,418) they have another quite important disadvantage.
It is impossible to adjust either the position around the roll cycle
of rotation at which vacuum is applied, or the period of time for
which it is applied, without stopping the paper-handling machine.
This is so because the shoe having the inner arcuate slot has to be
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inside the main machinery framing bearing against the end of the
rotating roll, and the support shaft for the roll essentially ha~ to
pass through the shoe, Whilst it might be feasible to change the
timing with the machine moving, by rotating the shoe slightly, to
change the length of time for which vacuum is applied requires
removing the shoe and altering the internal arcuate slot. This cannot
be carried out whilst the machine is runn-3ng.
In a similar way, the evacuated perforated paper handling rolls
commonly used in paper making machines which comprise an inner vacuum
chamber and an outer drum-like perforated shell cannot easily be
adjusted. In these devices, the vacuum is applied to the inside of
the shell by a radial slot along the length of the shell, which is
positioned where it is needed. The width of the slot is predetermined
and not adjustable, and further the vacuum is continuously applied to
the inside of the shell, to qid in part in removing water from a wet
paper web. A typical device of this type is described in U.S.
4,714,523.
This invention seeks to overcome these difficulties, and to
provide a paper web handling roll of this general type in which both
the timing of vacuum application, and the length of time of vacuum
application are adjustable from outside the machine by adjustment of
parts which do not rotate when the machine is running. It therefore
follows that adjustment of both timing and duration can be made whilst
the paper handling machine is in operation.
Thus in its broadest embodiment this invention provides a paper
machine vacuum roll together with a vacuum supply and control means,
wherein the vacuum supply and control means is stationary, within, and
substantially coaxial with the vacuum roll, consisting essentially of
in combination:
(i) a vacuum roll having a substantially cylindrical outer
surface and a coaxial inner bore communicating with the outer surface
by a plurality of holes comprising at least one row of radial holes
along a line substantially parallel to the axis of rotation of the
roll;
(ii) journal means at a first end of the roll;
(iii) journal means at a second end of the roll including a
substantially cylindrical coaxial aperture communicating with the inner
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bore and adapted to receive the vacuum supply and control means
therethrough;
together with a vacuum supply and control means comprising:
(iv) an outer vacuum box means in a vacuum tight-sealing
relationship with the inner bore comprising a first sealing means in
cooperating relationship with the inner bore adjacent the first end of
the roll, a first substantially cylindrical member attached to the
first seal and extending substantially for the length of the inner
bore, a second sealing means attached to the first cylinder and in
cooperating relationship with the inner bore adjacent the second end
of the roll, and a second cylindrical member extending through the
coaxial aperture of the second journal means, wherein the first
cylindrical member includes at least one arcuate slot extending for the
length of the cylinder between the first and second sealing means; -~
(v) an inner vacuum box means comprising a third cylindrical
member extending through the second and first cylindrical members
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including at least one longitudinal arcuate slot communicating with
the or each arcuate slot in the first cylinder, the third cylindrical
member having attached thereto adjacent one edge of the at least one -~
slot, and extendlng for the length of the at least one arcuate slot in
the first cylindrical member, a radially extending sealing means in
cooperating sealing relationship with the inner bore and with the ends
of the arcuate sIot in the first cylindrical member;
(vi) clamping means whereby the second and third cylindrical
members are retained in desired positions whilst the vacuum roll
rotates; and
~` (vii) vacuum pump means connected to the third cylindrical ~member. ~-
Preferably the vacuum roll includes at least two, and more
preferably~at least three rows of radial holes. -~
Preferably, the first cylinder includes one arcuate slot which
extends for at least 180 . ~ ~
Preferably, the third cylinder includes a third journal means, ~ -
such as a roller bearing, adjacent the first sealing means and in
cooperating engagement with the vacuum roll adjacent the first journal
means.
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The invention will now be described by way of reference to the
embodiment in the drawings, in which:
Figure 1 shows the parts of a roll in a d$sassembled state;
Figure 2 shows in part cross-section the roll of FIgure
assembled;
Figure 3 shows a cross-section substantially on the line II-II of
the assembled roll of Figure 2; and
Figure 4 shows an alternative construction of Figure 3.
In these figures like parts are similarly numbered. It is also
to be noted that some parts of Figure 1 are omitted for clarity from
Figure 2.
Referring first to mainly Figures 1 and 2, the line I-I denotes
the common cylinder axis for all of the parts making up the roll, both
the stationary vacuum feed and control means, and the rotating roll
parts. The roll is supported in the machine framework, shown
schematically at 10, 11 by suitable bearings 12. Outside the framing
at one end, as at 10, the timing hub 4 is located, which is held in
place typically by screws 2 in the slots 3. Alternatively toggle
clamps could be used. The hub 4 includes the locking set screws 6 and
8. The functioning of these parts will be described below.
One end journal, 15, of the roller runs in bearing 12, which
typically is a ball bearing, in the frame 10. Through this journal
extends the vacuum supply and control means, comprising the first,
second and third cylinders. The innermost third cylinder 18 has a
vacuum connection at 16, and is provided with three arcuate slots 20,
21 and 23 which function as vacuum ports. A single slot could be used
but is less effective. At its other end, the cylinder is closed with
a plug 24, typically by welding, which also includes a bearing spigot
or stud 26. Adjacent one side of the slots 20, 21 and 23 is attached
the sealing strip 22 (see Figure 3).
The third cylinder fits inside the first and second cylinders,
with the vacuum connection 16 protruding beyond the second cylinder
27. The ends 27 and 18 of the second and third cylinders are cut to a
length such that when the roll is assembled and installed, cylinder 27
can be engaged by the hub set screw 6, and 18 by the hub set screw 8.
The first cylinder comprises a vacuum box, and includes the first and
second sealing means 28 and 29, and the slotted first cylinder 30. As
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can be seen in Figure 3, the arcuate slot cut in the first cylinder
can entail cutting away more than half of the cylinder The sealing
strip 22 is the same length as the arcuate slot (Figure 2).
These static members fit inside the inner bore 31 of the rotating
vacuum roll 32. This roll has three rows of radial holes 34-1, 34-2
and 34-3. It is known to use both fewer rows of holes - either one or
two - and also more than three in such rolls. The roll 32 is attached
to the flange 14 adjacent the journal 15, and to the flange 41
adjacent the journal 40 typically by bolts 13. The journal 40 is
carried in the bearing 12 in the frame member shown schematically at
11. The roll will also be driven from this end by conventional means
(not shown). It is also convenient to support the inner end of the
vacuum supply and control means for example by way of the bearing 36
inserted into the bore 39 of the flange 41, which receives the spigot
26.
The functioning of the roll can be seen mainly from Figure 3. It
is assumed the roll is rotated in the direction X. It is to be noted
that only the roll cylinder 32 rotates: the remaining parts are
static. As the roll rotates, each hole 34-1, 34-2 and 34-3 in
sequence passes over the vacuum chamber A, and is in communication
with it over the arc C. The hole will then pass over the sealing
strip 22 and over the unevacuated chamber B, which is essentially at
atmospheric pressure and is on the trailing side of the seal 22, in
the direction of rotation of the roll. The vacuum remaining in the
the holes 34 is thus vented, and the paper web released. Over the
remainder of the rotation, the hole is sealed at its inner end. It
can thus be seen that the amount of vacuum applied is determined by
the pressure in the cylinder 18, and the time for which it is applied
by the length of the arc C. Both of these are controlled externally:
,the pressure by the pump setting, and the arc by means of the hub 4
and set screws 6 and 8. By using these set screws, the arc C can both
be altered in length, by rotating cylinder 18 relative to cylinder 30,
and the timing moved around the cycle, by rotating both together. The
timing around the cycle can also be adjusted by rotating the whole
hub 4 within the range allowed by the slots 3. Further, as neither of
these rotates with the cylinder 32, these adjustments can be made with
the machine running.
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There is a further advantage in this construction over the known
rolls. In the known rolls, vacuum is applied from the end shoe, and
also vented at the end of the roll. That is, all of the space
corresponding to the chamber A in this invention is evacuated and
vented each time the roll rotates. This both takes time, and is
noisy. In the roll of this invention, chamber A is always evacuated
and only the bores 34 are evacuated and vented as they pass over
chambers A and B. This is both far quieter, and also faster,
especially if the ports 20, 21 and 23 are correctly sizied to get the
best use of the available vacuum.
Furthermore, as the vacuum control and supply means is static, it
is feasible easily to assist in venting the holes 34 as they pass over
chamber B. As shown in Figure 4, an air pressure supply pipe 42,
connected at several points as at 44 to the chamber B can be fitted
inside the vacuum cylinder 18. By this means a positive pressure can
be maintained in the chamber B, thus aiding in venting vacuum in the
bores 34 as soon as they have passed over the sealing strip 22. A
suitable connection is made to the air supply pipe 44 adjacent the
vacuum connection 16 in this variation (not shown).
In the preceding description an embodiment is described in which
there is a single sealed vacuum chamber. This invention is not
limited to there being only one such chamber.
This construction can easily be adapted to a format in which
there is more than one sealed chamber between the vacuum cylinder 18
and the inner surface 31 of the roll 32. The first cylinder will then
have more than one arcuate slot, the ports 20, 21 and 23 will be
duplicated, and more than one seal 22 will be required.
It is inherent in the proceeding description that the inner bore
31 is cylindrical. It need not be so, and in fact a tapered form of
,construction can be used in which the inner bore widens from the seal
28 toward the seal 29 somewhat. The sealing strip is then also
machined to match the taper. In such a construction9 by providing end
thrust adjustment, to control entry of the spigot into the bearing 36,
the fit of the two vacuum cylinders into the inner bore can be closely
controlled. Experience has shown this is not necessary, and that
provided adequate machining tolerances are maintained a cylindrical
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construction is sufficient in which the inner bore has a ~ubstantially
constant internal diameter.
The material chosen for the sealing strip is also of some
importance since it is bearing against the moving inner face of the
inner bore. Three satisfactory materials, each of which are fiber
reinforced phenol- or urea-formaldehyde resins are Ryertex (Trade
Mark) and Robco 22 (Trade Mark), obtainable from Solidur Canada Co. of
Montreal, Quebec, and Ellslip (Trade Mark) obtainable from Beloit
Canada Inc., Sorel, Quebec. These materials both appear to give an
adequate seal life, and not to require any lubrication during service,
especially if, as has been found with Ryertex, the material is soaked
in a suitable lubricating oil for a period of time before use.
