Note: Descriptions are shown in the official language in which they were submitted.
3LOS~83
The present invention relates to a method andapparatus for continuous production of a fibrous pro-
duct having at least two strata of dissimilar density.
It is known to produce mineral fiber bodies
having dissimilar internal densities. Mineral flber
bodies, for instance glass fiber bodies of the above
type, are used in insulating conduits or the like, the
basic advantage of the dual or multiple density bodies
being in their capability of providing a relatively strong
outer surface of the insulation which is less subject to
mechanical damage than the internal layer of such an in-
sulation, while the internal layer retains good insula-
tion properties. Another application for multiple density
fibrous body would be an insulation panel or the like which
would have both its surfaces made of a higher density layer
while the intermediate portion of same would have a rela-
tively low density.
Multiple density fibrous bodies have thus far been
produced either by laminating two different fibrous bodies
together or, as disclosed in U.S. patent 3,652,377 issued
to J.W. Helmick on March 28, 1972, by activating and cur-
ing the binder contained in the fibrous body selectively
within predetermined areas of dissimilar density to per-
manently set the binder. The advantage of the latter
method is in that it does not require two separate supply
rolls of fibrous bodies and that it provides a product
that is not susceptible to delamination. The latter method
thus constitutes a significant advance in the art. Yet,
it possesses several drawbacks. Firstly, it is to be
appreciated that the inner portion of a "fiber pack" must
also be cured by heat. Due to the inherent insulating pro-
perties of the "pack", the use of Helmick invention is
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practically limited to lesser thicknesses of the product
and to relatively low densities. Moreover, the heating means
applicable in the latter method are of a rather special type
and thus require a considerable modification of the produc-
tion line. The relative proportion of higher and lower
density areas of the latter method is relatively difficult
to control. A still further disadvantage of the latter
method resides in that the glass fiber product is being
pulled between two heating plates which simultaneously com-
press the mat. Inasmuch as the mat normally has a verylow tensile strength, it is desirable that the mat be sub-
jected to as little pulling as possible.
It is an object of the present invention to over-
come the drawbacks of both of the known methods and to
provide a new and useful method and apparatus for produc-
ing a dual or multiple density fibrous bodies of the above
type.
According to the present invention, a method is
provided of continuous production of a fibrous product
or body having at least two strata, eac~ ~aY~ng ~ pre~
determined density. The method comprises the step of producing
a continuous, unitary body of a generally loose mass of inter-
meshed fibers containing uncured binder material. In sub-
sequent step, the body is advanced in longitudinal direc-
tion from a point at which the body is being produced. In
a further step, the body is split along a line generally
transverse to the direction of advancement of same to pro-
duce at least two portions or strata thereof. Both of
such portions are maintained unitary with the body. At
the same time, the two portions are spaced apart from each
other. The two separate portions are then advanced at
generally the same speed, generally in said longitudinal
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direction. In a subse~uent step, at least one of the
separate portionsis subjected to a treatment to produce
a predetermined density of fibers therein, the predeter-
mined density of the one portion usually being different from
that of the other of said portions. Eventually, the
two separate portions are brought back together and bond-
ed to each other to produce a unitary fibrous body having
strata or layers of different density. The treatment of
one of said separate portions to produce a predetermined
density is preferably effected solely by a compressive
force to increase the density of fibers. In other words, in
the preferred embodiment, the treatment of one of the two
separate portions does not involve the curing of thermo-
setting binder which is normally used in production of
fibrous bodies. The advantage of such treatment is in
that the whole volume of the binder material becomes cured
only after reuniting of the two portions which results
in a considerably stronger bond between the two strata.
The apparatus according to the present invention is
intended for use in a production line for producing fibrous
body; the line itself is well known in the art and comprises
fiber forming means, known per se, which includes a forming
hood and comprises at least one fiber forming spinner and
further includes coating means for coating the fiber with
uncured binder agent. The apparatus further comprises con-
veyor means for receiving the fiber from the fiber forming
and coating means for advancing same in the form of a gener-
ally loose mat in a longitudinal direction. A portion of
the conveyor means may be arranged to pass the mat through
binder curing means, also of a type known per se, arranged
to cure the binder deposited on the fibers.
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According to the present invention, mat splitting
means is arranged to be disposed downstream of the fiber
forming and coating means and upstream of the curing means.
The mat splitting means is arranged along a line extend-
ing generally transversely across and above the conveyor
means for splitting said mat to at least two portions.
The apparatus further comprises compacting means arrang-
ed downstream of the mat splitting means but upstream
of the curing means for compacting one of said portions
of the mat to increase specific density thereof. De-
flector means is disposed downstream of and adjacent
to the splitting means in proximity of the compacting
means. The deflector means extends from a location up-
stream of and close to the compacting means to a loca-
tion downstream of and adjacent to said splitting means.
It is to be appreciated, however, that the terms
"upstream" and "downstream" in this context do not
necessarily imply that the splitting means is a part
of a single line. Indeed, the forming and/or the curing
steps can be carried out in separate production lines
entirely independent of and even relatively remote from
the splitting and compactiny means. For instance, a
fibrous mat can be produced in a known device and reeled
in uncured state on a roll, the roll then being trans-
ported to the splitting and compacting device provided
at its end with another reel for reeling the uncured mat
twhich now has the dual density featurel for subsequent
transport of the roll to a known binder curing line for
curing and finishing the product.
However, for the sake of clarity, the invention
will now be described by way of an embodiment wherein the
forming, splitting, compacting and curing steps are all
carried out on a single production line, with reference
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to the accompanying drawings.
In the Drawings:
Figure 1 is a simplified, longitudinal, schematic
section of an apparatus according to the present invention,
showing typical features of the method of the present
invention, the apparatus including, for the sake of
clarity, both the forming and the curing section;
Figure 2 is a detailed perspective view of a
band saw used as splitting means as referred to above;
Figure 3 is a perspective view in the direction
from one side of the apparatus of Figure 1 and showing
in detail the splitting and the deflector means as re-
ferred to above;
Figure 4 is a perspective view from the opposite
side to that of Figure 3, showing the bottom portion of com-
pacting rollers used as compacting means for one of the layers
of t~e fibrous body; ~the compacted layer being omitted)
Figure 5 is a schematic sectional side view similar
to that of Figure 1, but showing only the fiber forming
portion of the apparatus as in Figure 1.
Turning now to the drawings, and in particular
to Figure 1, an apparatus is shown for continuous pro-
duction of a glass fiber mat which, eventually, has two
strata of dissimilar density. The two strata are design-
ated with reference numerals 1, 2, respectively. The
apparatus comprises fiber forming means 3 which, in itself,
is of a known type. In the embodiment shown in Figure
1, with reference to Figure 5, the fiber forming means
includes a forming hood 4 comprising a plurality of
fiber forming spinners 5, 5a normally disposed
in a row parallel to the direction ~, also referred
to as a longitudinal direction.
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The shown fiber forming means 3 is of a well known
type and therefore only shown in a schematic way. In gen-
eral, the forming means comprises spinners 5, 5a into which
molten glass is fed from a supply (not shown) onto rota-
ting surfaces 6, 6a to form on each surface a thin layer
of the molten glass. As the surfaces 6, 6a rotate at a
high speed, the molten glass is projected through openings
in same and the result molten stream is attenuated to form
veils 7, 7a of discontinuous flbers which pass through
binder rings 8, 8a each having a plurality of inwardly
turned spray nozzles 9, 9a for spraying the fibers with
~ heat curable binder composition. Steam jets 10 are
located beneath t~Q ~inder ring 8 for distri~uting the
fiber over the width of a conveyor lla, The conveyor lla
of Figure 5 forms, in the embodiment of Figure 1, a part
of the overall conveyor system. Tfi~ surface of conveyor lla
is permeable and a suction box 12 is located beneath
the forming section to assist in depositing the coated
fiber veil onto the surface for further conveying.
As mentioned above, the forming and coating means
described above have long been known and used in the art.
Similarly, it is known from the art that by selective
control of different operational characteristics of the
forming and coating parts it is possible to selectively
produce a fibrous mat of desired characteristics. Thus,
the supply of the binder agent to the rings 8, 8a can be
controlled in accordance with the desired rate of coating,
the holes in the surfaces 6, 6a can be of a larger or
smaller diameter to produce coarser or finer fibers, re-
3~ spectively, the coarser fibers generally tending to be
somewhat shorter. Another known way of controlling the
quality of the resulting product is selective temperature
1057~83
control of the incoming molten material, of the surfaces
6, 6a of spinners 5, 5a etc. Due to the fact that all
these features are well known and used in the art, there
is no need for further details of same.
Turning now back to Figure 1, the conveyors 11, lla
form a part of conveying system generally referr-
ed to as conveyor means for receiving the fiber from the
fiber forming and coating means and to advance the same in
the form of a generally loose mat 20 in longitudinal direc-
tion A. The conveyor means includes, in addition to theconveyors 11, lla, a qecond conveyor 21 ~l~ch, as best seen from
Figure 1, passes through binder curing means of the type
of forced air convection curing oven ~ the oven 22 itself
being of a well known type and therefore not being describ-
ed in greater detai;l.
According to the present invention, the apparatus
comprises mat splitting means 23 which is shown in greater
detail in Figure 3. It will be appreciated from Figure 1
with reference to the direction A that the mat splitting
means 23 is located downstream of the fiber producing
means of the type of the forming means 3 (which includes
the fiber coating means), but upstream of the oven
22.
The mat splitting means (Figure 3) is of the type
of a band saw 24 the lower run 25 of which is arranged
along a line extending generally transversely across
and above the conveyor 11. Preferably, the band saw 24
is of the type having a scalloped edge 26 which has been
found to minimize the build-up of glass wool on the blade.
With the conveyor 11 running indirection A, and while op-
erating the band saw 24, the band saw 24 splits the mat
20 into two portions or strata 1, 2.
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- The apparatus further comprises compacting means
27 which is shown in greater detail in Figure 4. As will
be appreciated from Figure 1, the compacting means 27 is
arrang~d downstream of the mat splitting means 23 and up-
stream of said curing means or oven 22 and is of the type
of two rolls 28, 2~ for compact~ng th~ port~on or stratum
1 of the mat 20, to increase specific density thereof.
With reference to Figure 4, it will be seen that the rolls,
which are viewed from the opposlte side to that of Figure
1, are arranged so that the roll 28 ~s fl~xedly secured
to the frame 30, whereas the opposite roll 2~ is mova~le
in horizontal direction B (Figure 1) and yieldably pressed
against roll 28 at a selectively adjustable pressure to
thus predetermine the density to which the stratum 1 is
compacted. The rolls 28, 29 are each provided with a
Teflon (trademark) coating on the surfaces thereof to
prevent the build-up of wool. Moreover, it will be seen
from Figure 4 that the roll 2~ is-prov~ded ~ a blade
or doctor 31 for removing any particles that might stick
to the teflon surface of the roll 29. Similarly, the roll
28 has a teflon blade or doctor 32 at the "trailing" edge
of which is arranged a curved shield 33 which (Figure 1)
is used in bringing the compacted stratum 1 back on top
of the stratum 2, before both strata enter the oven 22.
Disposed between the compacting means 27 and the
mat splitting means 23 is deflector means 34, which is
__
partly shown in both Figures 3, 4 and the operation of
which can readily be understood from the arrangement of Fig-
ure 1. The deflector means includes a Mylar (trademark)
coated, upwardly curved shield 35 (not shown in Fig. 4) loca-
ted adjacent to the rear edge of the band saw 2~. The trailing
edge of the shield-35, in turn, is adjacent to the forward
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e~d of tn~ upper run ~f a conveyor 36, whose rear end
termi-nate~-ahe~e-t-he n-~p=b~tMeen_r~lle-rs 28, 29. ~_
Turning back to Figure 3, the assembly carrying
the band saw 24 is unitary with a cross-beam 37 and is
mounted for selective vertical movement on frame 38. By
selectively moving the assembly up or down the frame 38,
the distance between the lower run 25 (Figure 3) of
bandsaw 24 and the conveyor can be adjusted. The posi-
tion of t~e forward shield 35 of the deflector means
34 is adjusted simultaneously to maintain the for-
ward edge of the shield 35 in a substantially co-
planar relationship with the lower run 25 of the
~and saw 24.
. .
In operation, a veil of glass fibers coated with
binder is produced in known way within the forming hood 4 and
deposited on the upper run of conveyors 11, lla to form a
continuous, unitary body of a generally loose mass of
intermeshed fibers containing uncured binder material.
The said unitary body has been referred to as mat 20.
The mat 20 is advanced in the direction of the arrow
A, i.e. in longitudinal direction away from the location
of the forming hood 4. The lower run 25 of band saw 24
subsequently splits the body 20 along a horizontal line
generally transverse to the direction A to produce two
portions of the body 20, referred to as strata 1, 2. It
will be appreciated that despite the splitting of the mat
20 into strata 1, 2, each of the strata 1, 2 remains un-
severed from, the body 20, i.e. unitary with same. The
strata 1, 2 are spaced apart from each other in the re-
gion following the mat splitting means. The two separate
portions or strata 1, 2 are then advanced generally in
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the direction A, the term "generally" meaning that the
upper stratum 1 is somewhat diverted from the direction
of the stratum 2 which follows more or less exactly the
original direction A.
The conveyor 36 runs at approximately the same speed
as conveyor 11, to avoid undesired pull on the mat 20 in
the region downstream of the splitting means 23. This,
in effect, means that the particles of the upper stratum
1 descend back on the stratum 2, following the region of
rollers 28, 29 in a slightly "retarded" fashion, due to
the fact that the portion of stratum 2 beneath the deflect-
ing means moves along a considerably shorter locus.
The upper stratum 1 is subjected to pressure
between the rollers 28, 21 whereby the density of fibers
contained in stratum 1 is increased to a
predetermined degree depending on the compressive
force between the two rollers 28, 29. The density of
the compacted stratum 1 downstream of the rollers 28, 29,of
course,is different from the density of the lower stratum
2. The shield 33 eventually brings the compacted stratum 1
back onto the surface of the lower stratum 2. It will be
appreciated that at this stage the binder is still uncur-
ed. The two strata 1, 2 then enter, as a unitary body,
tfis forced a~x conyeat~pn curlng oven 2Z l~n wfii~ch the binding
agent contained in the mat 20 is cured to firmly bond the
strata 1, 2 and the fibers therein.
Referring back to Figure 5, it will be appreciated
that if the type of fiber forming unit shown in that
Figure is used, the body 20 of the loose mass of inter-
meshed fibers may contain two strata in a cross-section
perpendicular to the direction A differ~ng from each
other in the volume of the binder and/or in the weight
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of the fibers or in the length of the fibers, or in other
properties, depending on suitable adjustment of the individual
spinners 5, 5a and the associated integers of the forming means
3. This arrangement makes it possible to vary the properties of
the mat 20. On splitting of mat 20 between thus produced layers
the properties of the eventually compacted or uncompacted layer
of the final product can be modified in accordance with pre-
determined requirements.
The apparatus and method of the present invention
have been tested under pilot plant conditions, wherein
the production parameters and the parameters of the final
product were as follows:
Number of Spinners: 2
Approximate Diameter of Glass Fibers: 55 HT (.00055")
Type of Binder Used: Phenol-Formaldehyde - urea
Ratio of Volume of Binder to Glass Fiber: (weight basis): 10%
Speed of Conveyor: 6 FPM
Thickness of Fibrous Body Prior to Splitting: 5"
Thickness of Strata After Splitting: Upper: 1/2" to 1 - 1/2"
Lower: 3 - 1/2" to 4 - 1/2"
Curing Conditions: Temperature: 350-F
Time: two min.
Thickness of the Upper Strata After Compacting: 1/8"
Overall Thickness of the Product After Curing: 1"
In a modification of the above pilot plant conditions,
the spinners are operated such that while the parameters for
the first spinner 5 are generally the same as above, the
approximate diameter of glass fibers produced by spinner 5a
is reduced by 28HT, with the binder-to-fiber weight ratio
changed to 4%, the remaining parameters remaining as in the
above example.
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Those skilled in the art will readily appreciate that
various departures are possible from both the apparatus and the
method as described above. For instance, it is possible to
produce a "sandwiched" insulation product with two surface
strata compacted, by utilizing two splitting and compacting units.
Another readily conceivable embodiment would have the compacting
rolls arranged vertically one above the other to reduce the
overall height of the deflection of the upper stratum 1 and to
possibly eliminate the need of the rear shield 33. The curing
apparatus, which in itself is well known, can be replaced by
another known apparatus e.g. a platen press.
It will also be appreciated that an embodiment of the
apparatus can also be provided, wherein the mat to be split
is produced by unreeling from a roll stand with the mat forming
stage being entirely separate from the splitting and compacting
apparatus as shown. Similarly, the curing oven can be replaced
with a reel stand for reeling the uncured mat after the process-
ing as described above. The reeled mat can then be transported
to a separate curing apparatus for unreeling and passing
through a curing oven or the like.
These and many other departures from the embodiment
of the invention as described above, however, do not depart from
the scope of the present invention as defined in the accompanying
claims.
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