[0001] This invention relates to the forming of fibrous products from generally long fibers.
More particularly, the invention relates to a method for collecting fibers centrifuged
from a rotary fiberizer.
[0002] Fibrous material which is used typically for acoustical or thermal insulation is
commonly formed by a rotary process. Molten material, such as glass, polymer material,
slag, rock or basalt, is placed into a rotating spinner having a peripheral wall with
orifices. The molten material is centrifuged through the orifices and formed into
fibers. The fibers are attenuated and directed downwardly by the action of a flow
or blast of gases discharged from an annular blower positioned circumferentially about
the spinner. The downwardly moving swirling flow of fibers and gases is referred to
as the veil. The fibers can be sprayed with a binder which adhesively binds the fibers
together at their contact points, or the fibers can be manufactured without binder.
The fibers are then collected to form a fibrous product or blanket.
[0003] A typical method of collecting the fibers includes a large hood with suction devices,
such as fans, situated underneath. The fibers are collected on a foraminous conveyor
positioned above the suction fans so that the suction force draws the fibers onto
the conveyor. For the production of long fibers the fibers should be collected within
a relatively short distance underneath the spinner, preferably within the range of
from about 0.1 m to about 1.5 m. If the fibers are not collected close to the spinner
the long fibers tend to bunch together and form generally parallel groupings of fibers,
referred to as "ropes". This roping effect is undesirable because of the formation
of a non-uniform fibrous product having areas of high density and areas of low density.
For the purposes of this specification and claims, the term "long fibers" means fibers
that are generally longer than about 10 inches (25 cm) as measured by the drape length
method.
[0004] Ideally, the long fibers should be collected without suction or with very low amounts
of suction to maintain high loft in the fibers. High amounts of suction compress the
fibers and reduce the overall recovery thickness of the insulation product. However,
if the fibers are collected close to the spinner on a flat foraminous conveyor with
low suction, a large amount of fiber material is blown away from the conveyor and
is not collected. Also, the use of suction devices is undesirable because of the high
levels of noise produced, and because of the expense involved.
[0005] Another method of collecting long fibers is to use a direct formed process. The fibers
are captured by two opposed conveyor surfaces. The conveyor surfaces are angled downwardly
inwardly to collect and consolidate the downwardly moving veil of fibers and convert
it into a flattened cross-sectional shape. The gases from the annular blower are suctioned
through the conveyor surfaces, which are foraminous. The conveyor surfaces are operated
in a downward direction to convey the fibers onto a second conveyor to form the fibrous
insulation product. High amounts of suction are used to capture the long fibers and
substantially prevent the fibers from being blown away from the conveyor and not collected.
[0006] It would be desirable to have a method of forming and collecting long fibers without
the use of high suction so as to prevent the undesirable compression of the long fibers,
and to produce a fibrous product that is of uniform density.
[0007] There has now been invented an improved method of forming and collecting long fibers
to produce a generally uniform fibrous product. The method of the present invention
for collecting the long fibers includes intercepting the fibers on a narrow collector
so that the fibers are draped over both sides of the collector, and then raising the
two sides of the draped fibers to form a generally planar blanket after the collector
and draped fibers have been removed from the downwardly moving gaseous blast. A narrow
collector is one which has a width that is substantially smaller than the diameter
of the spinner and the diameter of the corresponding veil. The invention does not
require the use of suction devices which can damage the fibers and lower the recovery
height of the fibrous product.
[0008] Molten material is introduced into a rotating spinner which has a peripheral wall
having a plurality of orifices. The molten material is centrifuged through the orifices
to create generally long fibers where the fibers are directed generally downwardly
away from the spinner. The fibers are intercepted on a collector so that the fibers
are draped over the collector. Preferably, the fibers are intercepted at a distance
beneath the spinner within the range of from about 0.1 m to about 1.5 m. The intercepted
fibers form first and second portions which are suspended over the collector and are
oriented generally vertically. The collector and intercepted fibers are then moved
away from the spinner. The first and second portions of the suspended fibers are raised
to a generally horizontal orientation, thereby producing a generally planar fibrous
product. The long fibers are preferably intercepted without the use of suction devices
for collecting the fibers, which can damage the recovery height of the fibrous product.
Preferably, the long fibers have an average length which exceeds 10 inches (25 cm).
The fibers can be manufactured with or without a binder applied to the fibers. The
fibers can also be formed from various materials, such as glass or polymer materials.
The spinner can also be adapted to form bi-component fibers which are formed from
two different molten materials having different coefficients of thermal expansion
which cause the fiber to curl when cooled. Bi-component fibers have high loft and
greater entanglement characteristics when compared to conventional straight fibers.
[0009] In a specific embodiment of the invention, the fibers are intercepted on a foldable
conveyor. The conveyor is directed underneath the spinner in a folded position with
the first and second surfaces of the conveyor both oriented generally vertically so
that the intercepted fibers are draped over the conveyor. The conveyor and intercepted
fibers are then moved away from the spinner. The conveyor is then unfolded so that
the first and second surfaces are oriented generally parallel to each other and form
a generally horizontal surface, thereby producing a generally planar fibrous product.
Preferably, the fibers are intercepted on the conveyor without the use of suction
devices. The width of the conveyor in the unfolded orientation is greater than the
width of the conveyor in the folded orientation, preferably at least 5 times greater,
and more preferably at least 10 times greater. In another specific embodiment of the
invention the fibers are collected on a single beam.
[0010] Fig. 1 is a schematic, partially sectioned, elevational view of a fiberizer showing
a prior art centrifuging process.
[0011] Fig. 2 is a schematic, partially sectioned, elevational view showing the collection
of fibers on a foldable conveyor of the present invention.
[0012] Fig. 3 is a schematic sectional view taken along lines 3-3 of Fig. 2 showing the
conveyor in the folded orientation with the suspended fibers draped over the conveyor.
[0013] Fig. 4 is a schematic sectional view taken along lines 4-4 of Fig. 2 showing the
conveyor in the unfolded orientation.
[0014] Fig. 5 is cross-sectional view of the conveyor similar to that shown in Fig. 2, but
having hollowed out portions for suction.
[0015] Fig. 6 is a schematic, partially sectioned, elevational view showing an alternate
embodiment of intercepting the fibers with a single beam collector and a ramping member.
[0016] Fig. 7 is a schematic sectional view taken along lines 7-7 of Fig. 6 showing the
fibers collected on the single beam collector.
[0017] Fig. 8 is a schematic sectional view taken along lines 8-8 of Fig. 6 showing the
ramping member raising the fibers.
[0018] Fig. 9 is schematic representation of suspended fibers collected on a rod using the
drape length method for measuring fiber lengths.
[0019] Fig. 1 illustrates a conventional method of forming fibers by the use of a fiberizer,
generally indicated at 10. The fiberizer includes a rotating spinner 12 having a peripheral
wall 14 with a plurality of orifices 16. Molten material 18 is introduced into the
rotating spinner as a stream 19 and is centrifuged through the orifices forming fibers
20. The molten material can be of any material suitable for the formation of fibrous
products. The material can be inorganic, such as glass, rock, slag or basalt, or can
be organic, such as polymer material. The fibers emanating from the spinner are attenuated
and directed downward by the action of a downward flow or blast of gases 22 discharged
from an annular blower 24. The blower is positioned circumferentially about the spinner
and the gases are discharged from the blower at high velocity to turn the direction
of the fibers downward, and in some cases to further attenuate the fibers. The gaseous
blast forms a veil 25 which is a generally downwardly moving column of swirling gases
and fibers.
[0020] In a conventional process, the fibers are collected or intercepted on a flat foraminous
conveyor surface 26 to form a continuous fibrous product, or blanket 28. It should
be understood that the rotary fiberizer method of forming fibers can be used to form
products other than a fibrous blanket, such as reinforced products. Of course, multiple
fiberizers can be used in cooperation with each other to form a single fibrous blanket.
The veil is typically drawn towards the foraminous conveyor by a strong suction force
which can be created by various suction devices (not shown), such as a fan. Without
suction, a substantial portion of the fibers would deflect or bounce off the conveyor
surface and not be collected.
[0021] By controlling the speed of the rotating spinner, the velocity of the gaseous blast
from the blower, and the distance from the blower to the spinner, and other factors
controlling the fiber forming environment, the length of the fibers can be altered
to form relatively short or long fibers. Preferably, the long fibers are bi-component
fibers. Bi-component fibers are formed from two different types of molten material,
each having different coefficients of thermal expansion so that the fiber curls when
cooled. Long fibers, however, tend to bunch together in the veil before being collected.
The long fibers sporadically form generally parallel groupings of fibers, referred
to as ropes 30. This roping effect is undesirable because of the formation of a non-uniform
fibrous blanket which has areas of high density and low insulating qualities, as well
as unpleasant aesthetics. The farther the fibers are collected away from the from
the spinner, the more likely roping will occur. The distance from the spinner 12 to
the collection surface 26 is indicated in Fig. 1 as distance "d". For shorter distances
d, the suction force is increased to draw the fibers onto the conveyor surface before
they are deflected off. However, high amounts of suction compress the fibers and reduce
the overall recovery thickness of the fibrous blanket.
[0022] For the purposes of this specification and claims, the term "long fibers" means fibers
that are generally longer than about 10 inches (25 cm) as measured by the drape length
method. The drape length method measures fiber length by measuring the length of fibers
collected on a narrow collecting rod, typically 0.25 inch (0.64 cm) in diameter. The
rod is moved horizontally with a smooth and swift motion through the entire veil,
thereby capturing or collecting fibers on the rod. The rod should be moved through
the veil near the spinner to avoid "roped" collections of fibers. The distance from
the spinner depends upon various factors, such as, the molten material being fiberized
and the spinner diameter. For a 15 inch (38 cm) spinner for fiberglass, the rod is
preferably at a distance of about 9 inches (23 cm) from the spinner bottom. The suspended
fibers will span across the length of the rod at a distance approximately equal to
the veil diameter.
[0023] Fig. 9 illustrates a typical collection of fibers suspended from a collection rod
70 used in the drape length method, where 71 is the approximate width of the veil.
With the rod held level, the average fiber drape length is measured by placing a tape
measure 73, or other measuring device, next to the rod and the general appearance
of the average length of the suspended fibers by sight is recorded. The general appearance
of the average length is represented by line 74 in Fig. 9. Regions 72 on the rod that
are clearly inconsistent with the rest of the fiber lengths collected on the rod are
neglected. These inconsistent regions are typically at the ends of the span of collected
fibers where the rod travels through a larger multitude of fibers in the veil. The
procedure can be repeated with a cleaned rod, especially if the fiber drape lengths
are difficult to read. If multiple readings are taken, the readings are then averaged
to determine the fiber drape length.
[0024] Figs. 2 and 3 illustrate a preferred embodiment of the present invention using the
same type of fiberizer 10, but with the long fibers being collected near the spinner
12 on a narrow collector, such as a foldable conveyor 32. The conveyor 32 has first
and second surfaces, such as flaps 34 and 36 which are pivotally attached to the conveyor.
The flaps are attached at a central portion 38 of the conveyor.
[0025] The section of the conveyor which is underneath the spinner has the flaps 34 and
36 oriented generally vertically, and the section of the conveyor is said to be in
a folded position. The long fibers 20 move downward from the spinner and are collected
by the conveyor by being draped over the central portion 38 of the conveyor. The collection
of draped or suspended long fibers has an inverted U-shaped cross-section, as seen
in Fig. 3. The fibers are not deflected or blown off the conveyor because most of
the high velocity discharged gases from the blower 24 are directed around the conveyor
flaps while the long fibers are caught or collected on the central portion 38. Although
a portion of the fibers will not be collected, the majority of the fibers will form
into a collection or mass by their own entanglement and will drape over the conveyor.
[0026] Because the gases of the downwardly moving gaseous blast are directed around the
conveyor, the central portion 38 of the conveyor can be positioned substantially closer
to the spinner than a flat collector could be. The conveyor of the present invention
can be used without suction devices, or used with low amounts of suction to help reduce
the amount of deflected fibers. Since high suction compresses and breaks the long
fibers, the recovery height of the fibers collected by the present invention is not
greatly affected due to the absence of high suction. Because of the ability to collect
the long fibers near the spinner, the formation of bunched groupings of long fibers
or ropes is greatly reduced. Preferably, the distance d is within the range of from
about 0.1 m to about 1.5 m.
[0027] As the conveyor moves in a direction 40 away from the veil and the downwardly moving
gaseous blast, the conveyor unfolds so that the flaps 34 and 36 are oriented generally
parallel to each other so that they form a generally horizontal plane or surface,
as can be seen from Fig. 4. The flaps lift the draped or suspended long fibers and
orient them to form a generally planar fibrous blanket. If desired, the continuous
fibrous blanket can then be cut on the edges for a consistent and uniform width. The
conveyor flaps can be lifted up in any suitable maker such as by traveling on a ramp
(not shown) or lifted by armatures (not shown). The conveyor can be any sufficient
surface which can be folded and unfolded, such as a plurality of hinged sections,
wire mesh, nylon webbing or a covering of flexible material.
[0028] As seen in Figs. 3 and 4, the horizontal width W of the conveyor in its folded position
is sufficiently shorter than the horizontal width W' of the conveyor in its unfolded
position. The unfolded width W' of the conveyor is preferably greater than about 5
times the width W of the conveyor in the folded orientation so that the gaseous blast
can be directed around the flaps. The closer the widths W and W' are to each other,
the more the foldable conveyor performs like a conventional flat conveyor having the
problems of fiber deflection.
[0029] Fig. 5 illustrates an embodiment of the conveyor 32 which is adapted to provide for
low suction to draw the fibers onto the conveyor. The flaps 34 and 36 are hollowed
out with a plurality of orifices 42 in outside surfaces 34a and 36a of the flaps,
respectively. Tubing 44 communicates with the hollowed out portion of the flaps and
a suction device (not shown) to provide for suction to draw stray fibers onto the
outside surfaces of the flaps. A low amount of suction force is preferable to maintain
the high loft in the fibers. High suction will damage the fibers and reduce the overall
recovery thickness.
[0030] Although the narrow collector has been described as a foldable conveyor, the collector
can be any sufficient collecting surface which is narrow enough to allow passage of
most of the discharged gases. Fig. 6 illustrates another embodiment of the invention
in which the narrow collector is a single beam, schematically shown as 50. The beam
can be of any suitable material or shape which is narrow enough to intercept the long
fibers and allow the blast of gases 22 to flow around it. The beam moves in the direction
40 away from the gaseous blast and collects the long fibers 20 in the same maker as
collector 32 by intercepting the long fibers so that the long fibers drape over the
beam. As shown in Fig. 7, the suspended fibers form first and second portions 52 and
54 which are oriented generally vertically. The beam carrying the fibers then travels
in the direction 40 away from the gaseous blast and veil, and between two opposed
ramped members, illustrated as ramp conveyors 56.
[0031] The ramp conveyors have an end 58 which is positioned generally vertically, and an
opposing end 60 which is positioned generally horizontally. The ramp conveyor has
a surface 62 which extends from the vertical end 58 to the horizontal end 60 in a
twisted configuration. The resulting shape of the surface 62 is much like a flat sheet
which has one end twisted or turned 90 degrees with respect to the other end. The
surface 62 of the ramp conveyor is moving in the direction 40 at approximately the
same speed as the beam. As the beam moves between the ramp conveyors, the first and
second fiber portions 52 and 54 contact their respective ramp surfaces 62 at the vertical
end 58 of the ramp conveyors 56. The fiber portions are then propelled in the direction
40 by the ramp conveyor and the beam, and simultaneously raised upward by the rising
surface of the ramp conveyor, as can be seen in Fig. 8. Eventually, the beam is directed
away from the fibers and the first and second portions are lying solely on the surfaces
of their respective ramp conveyors. When the first and second portions 52 and 54 of
the fibers are lying on the horizontal end of the conveyor, the portions are oriented
in a generally horizontal position, thereby forming a generally planar fibrous blanket
28. The continuously forming blanket is transported away by a take away conveyor 64.
[0032] It can be advantageous to have the collector be separate from the ramping member
because the collector intercepts the fibers in the harsh environment of the veil.
The embodiment with conveyor 32, as shown in Fig. 2, combines the functions of the
collector and the ramp into one structure. The collector is preferably constructed
from durable materials because the gases and fibers can be at very high temperatures.
However, the ramp member, such as the ramp conveyors 56 which are separated from the
single beam collector 50, is not subjected to the harsh veil environment and can be
constructed from conventional, less durable materials. Also, cleaning of the collector
32 may be required after each pass through the veil, whereas the ramp conveyors 56
may not require cleaning as frequently.
[0033] Although the ramp member is illustrated as ramp conveyors 56, the ramp member can
be any apparatus which is suitable for raising the first and second fiber portions
52 and 54 to a horizontal orientation. For example, stationary ramps (not shown) could
be used. The stationary ramps would be shaped similar to ramp conveyors 56 in a twisted-like
configuration. The surface of the stationary ramps could be made out of low frictional
material or adapted with air assisting features to minimize the frictional dragging
force. Vents on the surface of the stationary conveyor could provide for a cushion
of air for the forwardly moving fibers to travel upon. The vents could even be shaped
so as to direct the air in the forward direction 40 to assist in moving the fibers.
[0034] It is to be understood that the first and second portions of the blanket can remain
folded, and can be removed from the collector, and packaged in a folded manner, whereby
the end user unfolds the blanket for installation.
[0035] It will be evident from the foregoing that various modifications can be made to this
invention. Such, however, are considered as being within the scope of the invention.
[0036] The invention can be useful in the manufacturing of fibrous insulation and filtration
products.
1. A method of producing a fibrous product (28) comprising:
(a) introducing molten material into a rotating spinner (12), the spinner having a
peripheral wall (14) which has a plurality of orifices;
(b) centrifuging the molten material through the orifices to create fibers (20);
(c) directing the fibers away from the spinner with a downwardly moving gaseous blast
(22) which creates a downwardly moving veil (25) comprised of gases and fibers;
(d) intercepting the fibers on a collector (32,50) so that the fibers are draped over
the collector forming first and second suspended portions (52,54) which are oriented
generally vertically;
(e) moving the collector and intercepted fibers away from the veil; and
(f) removing the fibers from the collector.
2. A method according to claim 1, in which the fibers (20) are removed from the collector
(32,50) after raising the first and second portions (52,54) of the suspended fibers
to a generally horizontal orientation to produce a generally planar fibrous product
(28).
3. A method according to claim 1 or claim 2, in which step (d) comprises
intercepting the fibers on a conveyor (32), which is under the spinner, the conveyor
having first and second surfaces (34a,36a) which are both oriented generally vertically
so that the intercepted fibers are draped over the conveyor.
4. A method according to claim 3, in which the fibers (20) are removed from the conveyor
(32) after unfolding the conveyor so that the first and second surfaces are oriented
to form a generally horizontal surface to produce a generally planar fibrous product
(28).
5. A method according to claim 3 or claim 4, in which the width (W') of the conveyor
(32) in the unfolded orientation is at least 5 times the width (W) of the conveyor
in the folded orientation.
6. A method according to any one of claims 3 to 5, in which the fibers are intercepted
on the collector with suction which draws the fibers (20) onto the vertical first
and second surfaces of the conveyor.
7. A method according to any one of claims 1 to 5, in which the fibers (20) are intercepted
on the collector without suction.
8. A method according to claim 1 or claim 2, in which the collector is comprised of a
single beam (50).
9. A method according to any one of claims 1 to 8, in which the fibers are generally
longer than 10 cm (4 inches).
10. A method according to claim 9, in which the fibers (20) are generally longer than
25 cm (10 inches).
11. A method according to any one of claims 1 to 10, in which the fibers (20) are intercepted
at a distance (d) beneath the spinner (12) of 0.1 m to 1.5 m.
12. A method according to any one of claims 1 to 11, in which the fibers (20) are glass
fibers.
13. A method according to claim 12, in which the glass fibers are bi-component glass fibers.
14. A method according to any one of claims 1 to 11, in which the fibers (20) are polymer
fibers.
15. A method according to any one of claims 1 to 14, in which the fibers (20) are binderless.