METHOD AND APPARATUS FOR CUTTING OF FLEXIBLE FOAM

METHODE ET DISPOSITIF DE SECTIONNEMENT DE PRODUITS MOUSSES SOUPLES

English Abstract

ABSTRACT OF THE DISCLOSURE



An apparatus and process for the continuous
cutting of a generally cylindrical rod from soft flexible
polymeric foam slabs is disclosed. The apparatus includes
a drive for moving a length of the foam slab along a
predetermined path, a guide for restricting the movement
of such foam slab to movement along said predetermined
path, at least one rotary cutter having an open bore with
the axis thereof generally along said predetermined path
and in a position to continuously cut a rod from the
thickness of such foam slab as it is moved past said
cutter, a drive for rotating said at least one rotary
cutter at a speed sufficient to cut such foam slab
effectively as such foam is moved along said path, and an
arrangement for positively withdrawing a cut rod from the
cutter bore, the guide engages the foam slab adjacent the
cutters and forces the slab to move past the cutters and
in so doing the cutter slits the slab to allow such cut
rod to continue along such path and allow the foam slab
other than such rod to diverge from the path away from the
at least one cutter. The apparatus and process allow
convenient cutting of joint backer rods from soft flexible
polymeric foam slabs (open celled).

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:



1. A continuous process for cutting a generally
cylindrical rod from soft flexible polymeric foam slab
comprising
moving the foam slab along a predetermined path
towards a high speed rotary cylindrical-like cutter placed with
the axis thereof generally parallel to the predetermined path
with at least a portion of said cutter being within the
thickness of such slab,
cutting such foam with said cylindrical cutter to form
such rod which passes through said cutter and separating such
cut rod from the remaining portion of such foam slab,
engaging and withdrawing such remaining foam slab away
from said cutter, and
withdrawing such cut rod from said cutter.



2. A process as claimed in claim 1 wherein such foam slab
is guided in a manner to essentially limit the movement of such
slab to movement along said predetermined path, and cutting of
such foam in a manner to form such rod therefrom and in so
doing, causing such slab to split adjacent such cutter to allow
separation of such rod through such foam slab by guiding such
foam to one side of such cutter.



3. A process as claimed in claim 1 including slitting

such foam slab adjacent such cylindrical cutter to facilitate
removal of such cut rod.
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4. A continuous process for cutting a generally
cylindrical rod from soft flexible polymeric foam in the form
of a slab of predetermined width and thickness including moving
the foam slab along a predetermined path towards high speed
circular cutters spaced in the width of said slab and spaced
from each other,
cutting from within the thickness of such slab a
plurality of rods each spaced in the width of such foam a
distance at least equal to the diameter of such rods as such
slab moves past at least some of said cutters and cutting said
foam between said rods and the upper or lower surface of such
slab, moving the remaining portion of such foam along a second
predetermined path past further circular cutters positioned to
cut rods from the remaining portion of such foam slab spaced by
a distance approximately equal to the diameter of one of such
rods and forcing the remaining portion of such slab to separate
from such cut rods by moving in a manner such that the
remaining portion of such slab is displaced from said path and
said cut rods sufficiently such that such rods are exterior to
such slab.
5. A process as claimed in claim 1, 2 or 4 including
withdrawing such rods from said cutters under tension to
stretch such rods within said cutters reducing the diameter of
such rods thereby reducing the frictional forces between such
rods and said cutters within said cutters.
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6. A process as claimed in claim 1 wherein the portion of
such foam slab immediately downstream of the location of
cutting such rods is guided along a different predetermined
path to remove said cutters from such foam slab while such rods
pass through said cutters.



7. A process as claimed in claim 6 wherein guiding such
foam slab adjacent and upstream of said cutters includes
passing the foam slab between two opposed pressure rollers each
including surfaces for engaging such foam slab either side
thereof and maintain the lateral position of such foam slab
relative to said predetermined path of travel.



8. A process as claimed in claim 7 wherein said opposed
pressure rollers are spaced along the predetermined path and
generally thereacross to provide a limited region where such
foam slab is restricted and supported and cutting such foam
slab at such limited region.



9. A process as claimed in claim 8 including removing
such foam slab from said cylindrical cutters immediately
subsequent to cutting of such rods by guiding such foam slab
about a large roller which support such foam slab during
cutting such rods and at least partially guides such foam slab
to said second path after cutting of such rods.
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10. An apparatus for the continuous cuttting of a
generally cylindrical rod from soft flexible polymeric foam
slab comprising
means for moving a length of soft flexible foam slab
along a predetermined path,
guide means for restricting the movement of such foam
slab to movement along said predetermined path,
at least one rotary cutter having an open bore with
the axis thereof generally along said predetermined path and in
a position to continuously cut a rod from the thickness of such
foam slab as it is moved past said cutter,
means for rotating said at least one rotary cutter at
a speed sufficient to cut such foam slab effectively as such
foam slab is moved along said path,
means for positively withdrawing a cut rod from said
cutter bore,
said guide means engaging such foam slab adjacent said
cutters and forcing such foam to move past said cutter, such
foam slab in moving past said cutter being slit to allow such
cut rod to continue along such path and allow such foam slab
other than such rod to diverge from said path and in so doing
move away from said at least one cutter.



11. An apparatus as claimed in claim 10 wherein said means
for withdrawing such rod pulls on such rod to stretch the same
between said cutter and said withdrawing means to reduce
frictional engagement of such rod with the bore of said cutter.


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12. An apparatus as claimed in claim 10 or 11 including
a cutting blade associated with each cutter for
slitting of such foam slab between said cutter and an edge of
such foam slab to allow such foam to diverge from said
predetermined path after cutting of a portion of such rod
therefrom.



13. An apparatus as claimed in claim 10 wherein said means
for moving such soft foam slab along said predetermined path
includes drive rollers positioned across said predetermined
path and contacting such foam slab with sufficient pressure to
impart movement of such foam slab along said predetermined path
with the appropriate rotation of said rollers.



14. An apparatus as claimed in claim 10 wherein each of
said rotational cutters is cylindrical and of a length about
four inches, said means for withdrawing a rod from said cutter
necks the portion of such rod within said cutter to reduce the
tendency of the rod to rotate with said cutter.



15. An apparatus as claimed in claim 10 wherein said
cutter is conical and positioned to increase in diameter in the
direction of said predetermined path.



16. An apparatus as claimed in claim 10 having a plurality
of rotational cutters ganged together in a single support and
including a common drive means for driving of said cutters.
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17. An apparatus as claimed in claim 10 wherein said means
for withdrawing includes opposed pinch rollers immediately
downstream of said cutters driven at a speed to tension the
portion of such rods within said cutters.



18. An apparatus as claimed in claim 10 or 16 wherein said
cutters are mounted for movement generally parallel to said
predetermined path from an operating position to cut such rods
from the thickness of such foam to a fully withdrawn position
out of engagement with such foam.



19. An apparatus as claimed in claim 10 wherein said guide
means adjacent said cutter includes a cylindrical roller
orientated across said predetermined path and tangential
therewith, said roller in combination with a further roller
located downstream and below said cylindrical roller causing
the portion of foam slab other than such rod to quickly move
across an exterior surface of said cutters to a different
predetermined path.
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Description

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6402 l - 0140G




TITLE: METHOD AND APPARATUS FOR cuTrING OF FLEXIBLE FOAM
MATERIAL

BACKGROUND OF THE INVENTION
_ _
This invention relates to an apparatus and method
for cutting of sheets of soft flexible foam material into
cylindrical type rods suitable for use in joint backing
application. In particular, the invention relates to
apparatus and method for cut-ting of soft flexible
polymeric foam slabs to form long continuous lengths of
cylindrical backing rods from the thickness of the foam as
the slab is progressively moved past a cutting operation.
- Cutting of soft flexible polymeric foam has
proven difficult and attempts to extrude such foam into a
particular shape have also proven unsatisfactory as a
dense skin occurs. One method of forming particular
shapes from foam slab is disclosed in United States Patent
3,869,831, where shaper rollers grind the exterior surface
of the foam to produce the particular shape. According tu

this patent, first one surface of the foam slab is shaped
and then the foam is passed to a second station which does
a similar operation to the opposite side. This apparatus
has operated satisfactory 9 however it requires two
separate cutting operations which must be controlled and

aligned to assure the desired shape is achieved. It also
results in substantial amounts of fine scrap as the

surface has been ground.


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It is also known from United States Patent
3,009,848, to compress the sheet or block of soft plastic
foam and cut it in a particular manner often with straight
knives which upon release of the foam results in a
particular shape being achieved which is different from
the cutting knife. In this way, straight knives can be
used which are obviously much simpler to control relative
to specially shaped knives.
Other methods for producing cylindrical rods from
block foam have used a long hot wire which is inserted in
the foam and moved in a manner to cut the rod from the
foam block. This is a batch process operation and results
in fairly high manufacturing costs.
The cutting of soft flexible open cell polymeric
foam remains a problem particularly due to the foam's
resilent compression and elastic deformation resulting at
least partially from the low density and causes shifting
of the foam during cutting thereof. However, when the
foam block or slab is properly guided and of sufficient
thickness, it is fairly firm and it is only when much
smaller widths of the foam are cut that it becomes fairly
flexible. Therefore, the foam blocks or slabs have
somewhat di-fferent characteristics than the individual
cylindrical rods cut from the slab, caused by the reduced
size.
SUMMARY OF THE INVENTION
The process according to the present invention,
allows the continuous cutting of a generally cylindrical

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rod from soft flexible polymeric open celled foam slabs
which have been previously produced probably on a batch
basis. The process includes moving a foam slab along a
predetermined path towards a high speed rotary knife
having a bore parallel to the axis thereof and placed with
the axis generally parallel to the predetermined path such
that the knife is within the thickness of such slab. The
Foam is cut with the rotary knife to form cylindrical rods
which pass through the bore of the knife and separate from
the remaining portion of such foam slab. The rods are
engaged downstream of and withdrawn from the rotary knife
and the remaining Foam slab is guided along a path to
remove the knife from the thickness of the foam slab that
has been cut. Preferrably the foam slab is guided in a
manner to essentially limit movement of the slab to the
predetermined path and cutting of the foam rod from the
slab is done in a manner to cause the slab to split
adjacent the rotational knife to allow separation of the
rod from the slab by guiding the foam slab to one side of
the cutter while the rod passes through the bore of the
rotational knife. This process allows the cutting of rods
from the thickness of the foam slab and guides the foam
slab after the rod has been cut therefrom in a manner to
separate the slab from the rod and avoid the slab hitting
the support of the rotational knife. Preferrably the
length oF the rotary knives should

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be kept relatively short to reduce any deflection of the
knife in the length thereof.
The apparatus for cutting cylindrical rods frûm
blocks or sheets of open cell foam on a continuous basis
comprises means for moving a length of foam along a
predetermined path, guide means for restric-ting movement
of said foam to said predetermined path, at least one
rotary cutter having an open bore with the axis thereof
lû generally along said predetermined path and in a position
to continuously cut a rod from the thickness of such foam
as it moves past said cutter, means for rotating said
cut-ter at a speed sufficient to cut the foam slab
effectively as such foam slab is moved along the
predetermined pa-th, means for posi.tively withdrawing a cut
rod from the cutter bore, means for slitting a surface of
such foam slab to expose a por-tion of said cutter and
guide means engaging such foam adjacent the cutters and
forcing such foam to move past one side of said cutter by
2û passing said cutter through the slit in such foam and
causing separation of the cut rod from the foam slab with
the foam slab being diverted from the predetermined path.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown
in the drawings wherein:
Figure 1 is an end view of a foam slab showing
the outline of a number of cylindrical rods to be cut
therefrom;

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Figure 2 is a perspective view illustrating the
foam slab and cylindrical rods within the thickness of the
foam slab;
Figure 3 is a perspective view of the cylindrical
rod desired to be cut from the foam slab;
Figure 4 is a side view of a portion o~ the
apparatus used in the cutting of the cylindrical backer
rods;
Figure 5 is a partial perspective view showing
further details of the cutting station and the path along
which the foam slab is moved;
Figure 6 is a view of the drive arrangement used
for the cylindrical cutters;
Figure 7 is a partial perspective view showing a
two stage cutting operation where a first set of
cylindrical rods are cut followed by a second cutting
operation; and
Figure 8 is a top view of such a -two stage
cutting operation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
As shown in Figures 1 through 3, the purpose of
the present apparatus and process is for forming of the
cylindrical backer rods generally shown as 4 from open

cell foam slab 2 of a soft flexible polymeric -Foam. The
slab 2 is moved along a predetermined path generally
indicated as 5 and is guided along this path by rollers 6,

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lû and 12 in combination with the flat bed generally
indicated as 8. Preferrably, rollers 10 and 12 merely
move in response to rnovement of the foam block 2 and a
drive for pushing the foam slab towards the rotary cutters
generally indicated as 20 is provided upstream of rollers
6, 10 and 12. Rollers 6, 10 and 12 extend across the
width of the foam slab 2 and include extension surfaces 7,
11 and 13 respectively for engaging an edge of the foam
block to maintain the foam slab 2 laterally as it is moved
towards the rotary cutter 20. It is important -to maintain
the position of the foam slab as it is being cut and moved
past the rotary cutter 20 and this is accomplished by
roller 12 which is essentially adjacent the cutter 20 with
roller 10 being slightly upstream of roller 12. The foam
slab 2 does have some rigidity and this will be sufficient
to avoid the slab bulging upwardly between the cutter 20
and the area of the foam between roller 10 and the cutter.
The rotary cutter 20 is positioned within the
thickness of the foam and has a cutting edge 22 which will
cut the foam slab along cut line 3 of Figure 1 to form the
cylindrical backer rod indicated as 4. The cylindrical
backer rod will pass through the center bore 24 of the
rotary cutter 20 and is shown exiting the rear of the
cutter in Figure 4. In this way the cylindrical rod 4
formed in Figure 4 has been separated from the remaining
portion of the slab labelled 2a în

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Figure 4. The knife 14 provides a slit in the upper
surface of the slab 2 and allows the slab to be forced
downwardly over the rotary cutter to completely separate
the backer rod 4 from -the remaining portion of the slab
2a. Knife 14 is placed adjacent the rotary cutter 2û and
in some cases may not be required. For example, the
thickness of the foam remaining be-tween the rotary cutter
20 and the upper surface of the foam slab 2 may be such
lû that the remaining portion of the foam slab 2a rips as it
is moved downwardly over -the rotary cutter and past the
support therefore, due to guide roller 15. Knife 14 is
supported by member 36 adjacent cutting edge 22. To the
rear of the cutting edge 22, the rotary cutter 20 is
supported in a bearing 26 which is in turn supported in a
support block 28. To the rear of the rotary cutter 20 a
drive pulley 30 is provided which is in contact with drive
belt 32 driven by drive arrangement 34. The speed of the
rotary cutter 20 can vary in accordance with the speed of
the movement of the foam along bed 8 and characteristics
of the foam and the rotary cutter. The arrangement of
rollers lO and 12 is such that the movement of the foam is
restricted to maintain the cutter 20 within the thickness
of the foam and thereby assuring formation of the
cylindrical backer rod 4.

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An apparatus for cutting a plurality of
cylindrical backer rods -from a slab of soft flexible foam
is shown in Figure 5. In this case, a number of rotary
cutters 20 have been ganged together and have a gang drive
train generally as shown in Figure 6. This allows the
single drive 34 to be used for all of the cutters 20.
Each of the cutters 20 has an associated cutting knife 14
for slitting the upper surface of the foam slab to allow
the slab to move past the cutters after cut-ting of the
cylindrical rods.
Figure 5 also illustrates how the guide surfaces
7, 11 and 13 of rollers 6, 10 and 12 eFfectively limit
movement of the foam slab 2 to the predetermined path
indicated by arrow 5. The plurality of cylindrical backer
rods cut from the foam block 2 are shown at the extreme
left side and include an engaging and withdrawing
arrangement 40 for contact with the cylindrical rods 4 to
apply tension to the rods 4 between the cutting edge 22 of
each of the rotational cutters and arrangement 40. This
tension on the rods 4 assures the cylindrical rods do not
rotate in sympathy with the rotational cutters 20, due to
frictional engagement with the walls thereof, and also
serves to produce a slight temporary necking in the
diameter of the cylindrical rods further reducing any
frictional forces between the cutters and -the associated
cut rods. This tension is produced by using paired
engaging disks 52 and 53 either side of the

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cylindrical rod which positively engage the rod and are
driven by the drive arrangement 42 to apply tension to the
rod. The drive arrangement 42 is connected to these
members 52 and 53 via shaft 4~ which directly carries
members 53 and shaft 50 which carries member 52
operative]y driven by gear 44 and gear 46 with gear 46
directly secured to shaft 50. In this way, control of the
cut cylindrical rods is achieved and the tendency of the
cylindrical rods to rotate with the cutters is reduced.
Tension of the rods can be achieved by driving disc
members 52 and 53 at a speed to pull the rods 4 at a
linear speed slightly greater than the linear feed speed
of the foam slab 2 and allowing limited slippage of the
rods between the discs. This problem of rotation of -the
cylindrical rods can also be reduced by keeping the length
of the cutters fairly short. The rotational cutters shown
are oF cylindrical construction, however these can also be
in the form of conical cutters having increasing diameter
in the direction of travel of the foam. This increasing
diameter obviously will reduce the Frictional engagement
of the cut rod 4 with the rotational cutters, thereby
reducing the need to pull the cut rod 4 out o-f a cutter
20.
A simple arrangement for driving the rotational
cutters 20 by use of the one drive arrangement 34 is shown

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1 in Figure 6 which includes a plurality of drive gears 32
each secured to a cylindrical cutter. Each of these drive
gears 32 is interconnected to an adjacent cutter gear by
an intermediate gear 30. By driving any cylindrical
cutter or one of khe intermediate gears 30, all
cylindrical cutters will rotate.
Returning to Figure 5, the cylindrical cutters 20
are each supported within a support block 28 which is
mounted to be movable as indicated by arrows 60. This
allows the cutters to be positioned out of engagement with
the foam to allow feeding of the Foam slab -through the
apparatus and when desired to be moved to a cutting
position such that a cylindrical rod is cut from the
thickness of the foam prior to the remaining portion of
the foam being drawn across the cutters as it is diverted
from the predetermined path.
Figures 7 and 8 illustrate a two stage
application where the foam slab 2 first has one set of
cylindrical backer rods cut thereFrom each of which is
spaced from another by a distance greater than the
diameter of such a cylindrical backer rod. The first
stage of the cutting is generally indicated as station 100
with a second cutting operation indicated as station 102.
Each set of rotary cutters is moveable into the path of
the foam adjacent a lower support roll with a further
roller placed upstream such that movement of the foam at

6402 ~ 5~ 0140G

the cutter is limited to the predetermined path over which
the foam is forced. As illustrated in Figure 8, each of
the rolls can include guide surfaces for engaging the edge
of the foam and maintaining the position of the foam with
respect to the lateral direction. The first set of
cylindrical knives are supported in a common block 28a and
the second set of cylindrical knives are supported in
common block 28b. The rollers for the first station are
indicated as lOa and 12a and the rollers for the second

station are indicated as 12b and lOb. This two stage
operation may be of benefit where placement of cylindrical
knives closer to one another is difficult or in the case
where conical cutters are used. If the foam slab is of
insufficient rigidity during the second stage cutting due
to removal of the rods at the first s-tage stationary
plugsd can be used to fill -the area of the foam slab from
which the rods have been removed at least adjacent the
second set of cutters. The slab can move passt such plugs
due to the slit previously formed at the first set of
cutters.
Although various preferred embodiments o-f the
present invention have been described herein in detail, it
will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the


spirit of the invention or the scope of the appended
claims.