Note: Descriptions are shown in the official language in which they were submitted.
dV0 93!1)595? ~ ~ ~ ~ ~ ~ ~ PCT/A~L192/00486
1
T D ~P~RDOARD R ~i()N AND APPARATUS TI~EREFQR
This invention relates to improved methods of and apparatus for forming paper
board structures in which two corrugated mediums are bonded together at their
flute
tips. A structure of this kind is disclosed in Australian Patent 567833 which
is
incorporated herein by reference.
One apparatus for forming such corrugated board structures is disclosed in
Australian Patent No. 609089 (17926188) which is also incorporated herein by
reference. Additionally there are variations of the basic apparatus as is
currently
disclosed in Australian Patent No. 615,053 which discloses the 4-roll
apparatus
i 0 wherein one of the corrugating rolls functions also as a carrier roll
which transfers the
bonded mediums to the liner bonding zone and also US Patent No. 4,935,082
which
replaces the carrier roll with the toothed belt. The invention as described
and defined
herein is equally applicable to the variations of the basic apparatus; wherein
flute tip to
flute tip bonding is required.
One of the major difficulties of producing a paper board structure wherein two
corrugated mediums are adequately bonded together at their flute tips, is
accurately
aligning the peak of the flutes of the corrugated medium along the entire
width of the
corrugated mediums. The problem arises from the fact that pressure between the
flute
tips along their entire length causes misalignment thereof.
2 0 The present invention is predicated on the discovery that the problem of
maintaining the corrugating rolls flute tip to flute tip arises from the fact
that the
entire board making apparatus can generally lack rigidity. It is thought that
the lack of
rigidity is mainly attributable to the lack of rigidity in the support frame
and also in the
corrugating rolls and shafts which twist during operation. Thus as a result of
movement
a 5 of the corrugating rolls and the frame the flute tips of the rolls become
misaligned.
The prior art has dealt with the problem of aligning intermeshing corrugating
rolls as distinct from the problem of maintaining alignment of corrugating
rolls which
contact flute tip to flute tip. Indicative of the prior art is US Patent No.
4196046 which
discusses the .problem of aligning intermeshing corrugating rolls to adjust
the clearance
3 0 between the flutes. The patent describes the use of a pair of meshing
helical gears with
an axial adjuster attached to one of the gears in order to adjust the
clearances between
the flutes of the intermeshing corrugating rolls. Since the clearance between
the
intermeshing rolls can be adjusted, wear and tear on the machine is reduced as
well as
fracturing of the paper web due to clearance deterioration.
~V~ 9~/OS9S7 PCI'/AU92/00485
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If is an object of this invention to improve and overcome at least same of the
problems of the apparatus disclosed in AU 609089 and variations of the same as
previously discussed and discussed in Patents AU615,053 and US4,935,082 and
thus
improve the quality of the paper board product and the efficiency of the
process.
This invention provides an improvement in the basic apparatus and also the
variations of the same as previously discussed.
The invention therefore provides a ~rrugated board making apparatus capable of
forming corrugated boards having two fluted mediums bonded together at the
flute tips,
comprising two pairs of corrugating rolls synchronised so that the two fluted
mediums
1 0 are oriented for precise flute tip to flute tip bonding, wherein
cooperating end gears are
provided on the corrugating rolls which orientate the fluted mediums for flute
tip to
flute tip bonding.
In particular, the end gears are provided specifically on the corrugating
rolls
which co-operate tip to tip and bring the corrugated mediums together for tip
to tip
bonding.
More preferably, a set of end gears is fitted to each end of the said
corrugating
rolls.
The provision of the co-operating end gears advantageously aids in maintaining
identical surface speed at the tips of the flutes to be bonded, thus resulting
in the precise
2 0 alignment of the corrugating rolls to each other. Thus the alignment of
the flute tips of
the respective corrugated mediums is achieved, which is essential in order to
obtain
consistent enhancement of board performance and maximum reduction in medium
and
liner weights. The benefits of providing this type of board structure are set
out in
Australian Patent No. 567,833.
2 5 ' End gears are preferably but not essentially fitted to each end of each
pair of
central corrugating rolls and consist of one full face gear and one split face
gear to allow
adjustment of backlash.
It is apparent that the prior art apparatus does not discuss or even suggest
the
possibility of using end gears in relation to the bonding together of
corrugated mediums
3 D at their flute tips which align and bond. The prior art is only concerned
with the actual
corrugating process and intermeshing corrugating rolls.
The end gears are preferably abutting end gears and are preferably installed a
short distance from the grooved face of each corrugating roll advantageously
assisting in
reducing the twisting of shafts. The use of abutting end gears allows the use
of
3 5 conventional vacuum corrugating rolls with standard sued trunnions and
minimises the .
~V~ 9/05957 PCI'lALJ92100~6
?~~~J.~~
3
torsional deflection which generally occurs. By providing abutting end gears
to both
ends of the corrugating rolls the general rigidity of the apparatus and the
reduction in
the twisting of the shafts is further enhanced.
The end gears may be non-abutting end gears or can be fitted outside the
vacuum
collectors and also outside the machine frames. Non-abutting gears can be used
when the
corrugating rolls have larger trunnions and thus the ability to resist the
high torsional
stresses arising from the point to point pressure occasioned during the tip to
tip bonding
process.
The end gears are preferahly precision ground so that the intermeshing is
precise.
The end gears can be spur gears or helical gears.
The gears may be split. If there are gears provided at each end they are
preferably split at each end. The split gear may then mate with a gear of
larger face
width on the other corrugating roll. This arrangement assists in taking up
backlash and
1 5 allows transmission of at least 50% of the applied torque, thus
preventing, further the
twisting of the corrugating rolls and shafts.
lNhen the helical gears are used as abutting end gears, the fitting of shims
between the end faces of the corrugating rolls and the helical gears may be
required
when the helical gears are adjusted axially.
2 0 If helical gears are fitted to both ends of the roil, the helices on each
gear can be
opposing to ensure thrust forces cancel each other out. If helical gears are
only fitted to
one end, additional thrust bearing capacity may be required to counteract the
axial
thrust created by the helical gears and prevent twisting of the corrugating
rolls and
shafts out of tip to tip alignment.
~, 5 ~ A preferred embodiment of this invention will now be described with
reference to
the drawings:
Figure 1 shows a schematic view of a single facer unit of the kind disclosed
in
Australian Patent No. 609089.
Figure 2,shows a cross-section view of the corrugating rolls with abutting end
3 0 gears attached.
Figure 1 illustrates a single facer unit of the kind disclosed in Australian
Patent
No. 609089. The corrugating medium, 1 and 2, maintained on mill roll stands
(not
shown) and generally passed over a preheater (not shown) is fed onto one
(items 3 and
~) of a pair of corrugating rolls, 3 and 4 and ~ and 6. The medium, 1 and 2,
is
3 5 corrugated and then adhesive is applied to at feast one of the surfaces of
1 or 2, by an
CVO 93dQ5957 PCTdAdJ92d0043b
~l~r~~~~ 4
adhesive station 7. The corrugated medium, 1 and 2, is then joined together
flute tip to
flute tip, when brought together by corrugating rolls 4 and 6. The two
combined
corrugating mediums are fed onto the carrier roll 12 and after glue is applied
to the
flute tips, they are transported to the bonding zone wherein the liner 9 is
brought into
contact with the flute tips and heat applied by heater 11. The carrier rolls
12 then
transports the combined liner and mediums to a point where the product is fed
into an
inclined transport conveyor t 4 for discharge on to the corrugator bridge.
In accordance with variations of the basic apparatus, it is noted that the
carrier
roll t 2 can be substituted with a toothed belt.
1 0 Figure 2 illustrates an embodiment of the present invention, wherein end
gears
15A and 15B and 16A and 16B are fixed to the corrugating rolls 4 and 6 of the
single
facet unit which are the corrugating rolls which align and bond the corrugated
medium
in flute tip to flute tip arrangement. This embodiment illustrates the use of
the split
spur gears t 5A and 15B and 16A and 16B abutting the corrugating rolls 4 and
6. It
1 5 should be noted that in order to maximise the rigidity of the apparatus
and the reduction
of twisting in the aligning corrugating rolls, end gears should be placed at
each end of the
aligning corrugating rolls. The end gears 15A and 15B and 16A and 16B in this
embodiment fit within the space between the vacuum collector 17 and the
corrugating
rolls 6 and 4. It should be noted that if repetitive wear patterns on the
corrugating rolls
2 0 are not acceptable, space can be allowed so ail four corrugating rolls may
be able to move
axially relative to each other. The vacuum collectors 17 and connections
therefrom to
the corrugating rolls 4 and 6 can pass through the end gears 15A, 158, 16A and
16B to
communicate with the corrugating rolls 6 and 4. The vacuum collectors 17 are
spring
loaded by spring arrangement 19 to ensure a secure but resilient contact
between the
25 end-gears (15A, 15B, 16A and 16B) and the vacuum collector system 17.
The end gears need not always abut the corrugating rolls and this is dependent
on
the diameter of the corrugating rolls with larger diameter shafts. In larger
diameter
rolls, which can be used when flutes of greater height and tower flute pitch
are required,
the end gears need not abut the rolls and can be even housed outside of the
main housing.
3 0 Furthermore, when vacuum is not used to assist in retaining and carrying
the cardboard
on the corrugating roll and the alternative fingers are used, it is possible
to separate the
end gears away from the corrugating rolls, since larger rolls can be used.
In order to produce a particular flute, for example Thai disclosed in
Australian
Patent No. 567$33, the diameter of the corrugating rolls and shafts may be
limited in
WO 33/05957 PCf'/AtJ32/004t36
~~.~~~~2
_
order to produce the desired flute pitch and depth. tn these cases ii may be
necessary to
abut the end gears in order to maximise the rigidity of the apparatus.
Furthermore, the face width of split spur gear 16A is extended to assist in
taking
up backlash and allow transmission of the applied torque. Generally the face
width of the
5 end gears is governed by the braking torque required which as a general rule
is at least
three (3) times the drive torque created. End gear 16A and 16B is driven by
its
cooperation with end gears 15A and 15B and drives the carrier roils 12 via a
ring gear
(not shown) attached to the carrier roll 12. Similarly the end gears can drive
a toothed
belt if used.
1 0 The end gears 15A and 15B and 16A and 16B may be fixed to the shafts of
the
corrugating rolls 4 and 6 by any locking assembly, for example mufti-taper
lock
sleeves, stem 21. The only requirement of the locking assembly is that the
gears are
precisely retained in position to transmit high peripheral forces without
circumferential movement.
To secure the split gears 15A and 15B to each other fixing screws 20 may be
used which also allow for adjustment of the gears relative to each other in
order to
reduce backlash. Similarly fixing screws 20 can also be incorporated on split
gears 16A
and 168. The end gears 15A, 15B, 16A and 163 depending on their proximity to
the
corrugating rolls may have a shroud (not shown) shielding the board being
processed and
2 0 preventing entanglement of the board in the rotating end gears.
It is noted that whilst the end gears must be applied to at least the
corrugating
rolls which are directly involved in flute-tip to flute-tip bonding, end gears
can be
applied to other rolls such as carrier rolls, or toothed belt mechanisms.
The frame 18 may also be reinforced and/or improved in order to increase frame
z 5 rigidity and thus generally greater apparatus rigidity.
The above improvements to existing machinery, aid and assist in
providing a better board product, and produces the board product more
efficiently
resulting in reduced machine wear and raw material use.
