Method and apparatus for collecting fibrous material

A method and apparatus for collecting fibrous material in which a stream of fibrous material is directed towards a collection surface and a flow of gases is discharged substantially parallel to the stream and sufficiently close to the stream to expand the stream as it moves toward the collection surface.

TECHNICAL FIELD 
This invention relates to forming and collecting fibers from streams of 
fibrous material, such as fibrous mineral material, and collecting the 
fibrous material on a collection surface. In one of its more specific 
aspects, this invention relates to directing a stream of fibrous material 
toward a collection surface, and distributing the stream across the width 
of a collection conveyor. 
BACKGROUND OF THE INVENTION 
A common practice in collecting fibrous material is to direct the fibrous 
material as a stream or veil toward a collection surface, such as a 
foraminous conveyor, which receives the fibers and forms a mat or fibrous 
web thereon. For various reasons it is desirable to produce wider and 
wider mats or packs on the collection surface, particularly wider than the 
width of the stream of fibers. It is therefore desirable to distribute the 
fibers in order to cover the entire width of the collection surface. It is 
often the case that the collection conveyor has a width of up to six times 
or more of the width of the stream of fibrous material. 
In order to evenly distribute the fibers from the stream across the entire 
width of the collection surface it is a common practice to lap the stream 
of fibers with an oscillating cylinder resembling an open-bottomed bucket. 
The oscillating bucket distributes the fibrous material rapidly from side 
to side of the collection surface, thereby providing relatively even 
distribution. Another method commonly utilized in distributing streams of 
fibrous material is directing the stream toward the center of the 
collection conveyor, and diverting some or all of the stream periodically 
to either one side or the other side of the conveyor with blasts of air. 
The air blasts are directed generally perpendicularly to the stream of 
fibrous material to impart a sideways distributive force thereto. 
One of the problems with the above method for distributing streams of 
fibers is that they all consume significant amounts of energy. Also, the 
process of lapping the entire stream of fibers can cause nonuniformity as 
the fibers are laid down on the collection surface. The use of air blasts 
to distribute the stream of fibers causes problems because the fibers are 
accelerated toward the collection surface and have a tendency to bounce or 
blow back from the collection surface, thereby necessitating suction fans 
beneath the collection surface to hold the pack down onto the collection 
surface. The energy required to operate such suction fans is substantial, 
and all of the exhausted air must be treated for pollution control 
purposes. Excessive suction by the fans tends to crush some of the fibrous 
material in the pack. Also, the air blasts increase the general level of 
turbulence in the pack forming hood. The oscillating buckets lapper is 
limited to the production of relatively narrow fibrous packs, and is not 
suitable for use on wide machines. The method and apparatus of the 
invention are directed towards the solution of the above problems. 
SUMMARY OF THE INVENTION 
According to this invention there is provided a method for collecting 
fibrous material in which a stream of fibrous material is directed toward 
a collection surface, and further including discharging a flow of gases 
substantially parallel to the stream and sufficiently close to the stream 
to expand the stream as it moves toward the collection surface. The 
velocity of the fibrous material reaching the collection surface is 
reduced by the action of the flow of gases, thereby enabling a reduction 
in the suction requirements beneath the collection surface. Also, the 
amount of energy required to clean up the exhausted gases is reduced due 
to the lower volume of gases being exhausted. Since the fibers and 
associated gases reach the collection surface at a lower velocity, blow 
back and bouncing problems are substantially reduced. Also, the reduction 
in suction forces beneath the collection conveyor reduces the crushing of 
the bottom portion of the fibrous material in the pack. 
In a specific embodiment of the invention, the flow of gases is discharged 
at a speed sufficiently greater than the speed of the stream of fibrous 
material to expand the stream as it moves toward the collection surface. 
The flow of gases can be discharged at a speed of up to about 10 times the 
speed of the stream of fibrous material. The speed or momentum of the flow 
of gases can be sufficient to generate a lower pressure outside the stream 
of fibrous material and to achieve a boundary layer acceleration resulting 
in diffusion of expansion of the stream. 
In another embodiment of the invention, two flows of gases are discharged 
from two loci oppositely disposed about the stream of fibrous material. 
In a preferred embodiment of the invention, a generally cylindrical veil of 
fibrous material is directed toward a collection conveyor and the veil is 
expanded to substantially cover the width of a collection conveyor. 
In another preferred embodiment of the invention, two flows from two 
nozzles are discharged, each nozzle being disposed through an arc within 
the range from about 90 degrees to about 150 degrees of the circumference 
of the veil. Each nozzle can be disposed through an arc of about 120 
degrees of the circumference of the veil. 
According to this invention, there is also provided a method of collecting 
fibrous mineral material of the type in which a generally cylindrical veil 
of fibrous mineral material is directed generally downwardly toward a 
collection conveyor, the improvement comprising discharging generally 
downwardly two flows of gases substantially parallel to the veil and 
sufficiently close to the veil to expand the veil to substantially cover 
the width of the collection conveyor, the flows of gases being discharged 
from two nozzles oppositely disposed about the veil through arcs of about 
120 degrees of the circumference of the veil. 
According to this invention, there is also provided a method for collecting 
fibrous material of the type in which two or more streams of fibrous 
material are directed toward a collection surface, the improvement 
comprising discharging flow of gases substantially parallel to the streams 
and sufficiently close to the streams to expand the streams as they move 
toward the collection surface, and further controlling the distribution of 
the fibrous material on the collection surface by controlling the 
expansion of the individual streams of fibrous material. 
According to this invention, there is also provided apparatus for 
collecting fibrous mineral material of the type in which a generally 
cylindrical veil of fibrous mineral material is directed toward a 
collection surface, the improvement comprising two nozzles oppositely 
disposed about the veil, each nozzle discharging a flow of gases 
substantially parallel to the veil, each nozzle being positioned 
sufficiently close to the veil to cause the stream to expand as it moves 
towards the collection surface, and each nozzle being adapted to discharge 
the flow through an arc within the range of from about 90 degrees to about 
150 degrees of the circumference of the veil. Each nozzle can be adapted 
to discharge its flow through an arc of about 120 degrees of the 
circumference of the veil. 
In one embodiment of the invention, the nozzles are adapted to discharge 
the flows at speeds of about ten times the speed of the veil. 
In a preferred embodiment of the invention, each nozzle is adapted at its 
downstream side with a diverging surface. 
In a most preferred embodiment of the invention, each of the nozzles is 
adapted at its upstream side with a converging surface.

DESCRIPTION OF THE INVENTION 
For purposes of illustration, the principles of the invention will be 
described in the context of a glass fiber forming and collecting 
operation. It is to be understood that the invention includes uses with 
other mineral fibers and with other fibrous materials, and with 
alternative fiber forming methods. 
As shown in FIG. 1, spinner 10 can be mounted for rotation on quill 12 and 
can have orificed peripherial wall 14. Molten glass stream 16 can drop 
into the bottom of the spinner and flow outwardly and upwardly to the 
spinner peripheral wall through which the glass passes as fibers 18. The 
fibers can be maintained in an attenuable state by the heat from annular 
burner chamber 20, and the fibers can be turned down into a stream or veil 
22 of fibrous glass by the action of annular blower 24. Binder can be 
applied to the fibers in the stream of fibrous material by any suitable 
means, such as binder nozzles 25. The veil is directed toward collection 
surface 26, upon which the fibers collect as mat or pack 28. The fiber 
distribution and collection process occurs generally within forming hood 
30, which defines the width of the collection surface and of the pack. 
Suction means, not shown, create a partial vacuum in plenum area 32 
beneath the collection surface in order to hold the fibrous material down 
onto the collection surface. 
Means, such as nozzles 36, for discharging flows 34 of gases substantially 
parallel to the veil are positioned sufficiently close to the veil to 
expand the veil as it moves toward the collection surface. In order for 
the flow of gases discharged from the nozzle to expand the veil, the veil 
must come within the influence of the flow of gases. As shown in FIG. 2, 
the nozzles can comprise downwardly directed slot 38 supplied by manifold 
40 which can in turn be supplied from a source of air, not shown, via 
conduit 42. The nozzle can be adapted at its downstream side with a 
diverging surface, such as diffuser flap 44. The surface of the diffuser 
flap can be a Coanda surface to facilitate the divergence of the flow of 
gases and the expansion of the veil. As the flow of gases moves downwardly 
from the nozzle slot, it pulls or diverts a portion of the veil outwardly 
from the center of the veil, thereby causing the veil to expand and to 
decelerate. In the preferred embodiment, the diffuser flap is at an angle 
of approximately 30 degrees from the center line of the veil. Each nozzle 
can also be adapted at its upstream side with a converging surface such as 
inlet control surface 46, which in the preferred embodiment is at an angle 
of approximately 15 degrees from the centerline of the veil. The inlet 
control surface enables the nozzles to be placed sufficiently close to the 
veil for proper divergence without having some of the veil flow behind the 
nozzle. 
The flow of gases discharged from the nozzle is usually introduced at a 
speed higher than the speed of the veil. The nozzle can be adapted, for 
example, with a slightly subsonic design, enabling a discharge velocity of 
the flow of gases of approximately 300 meters per second. As the veil 
passes the nozzles, its speed is approximately 30 meters per second and 
therefore the speed of the flow of gases is about 10 times the speed of 
the veil. 
As shown in FIG. 3, the apparatus can be adapted with two nozzles, with 
each nozzle adapted to discharge its flow through an arc within the range 
of from about 90 degrees to about 150 degrees of the circumference of the 
veil. Preferably, each nozzle will cover an arc of approximately 120 
degrees. 
The system of fiber distributing and collecting shown in FIG. 4 includes 
paired nozzles expanding a plurality of veils of fibers prior to their 
deposition on the collection conveyor. It can be seen that the invention 
can be applied to a system containing any number of veils. 
The system of fiber distributing and collecting, as shown in FIG. 5, can 
include, for example, four veils 48A, 48B, 48C, and 48D. Each veil can 
have associated with it nozzles 50A, 50B, 50C, and 50D and the associated 
supply conduits 52A, 52B, 52C and 52D. Since there is only one nozzle for 
each veil, the operation of the nozzles diverts and expands each veil 
toward one side or the other of the collection surface on which is formed 
pack 54. The flow of air into each of the nozzles can be controlled by 
control means 56A, 56B, 56C, and 56D. The control means can be any 
suitable means, such as solenoid valves, for controlling the flow of air 
into the nozzles. By controlling the air flow into each of the nozzles, 
the expansion of each veil and the distribution of the fibers from each 
veil, can be controlled. Thus, for example, should the right hand edge of 
the pack being collected on the collection surface as shown in FIG. 5 be 
of lower density than desired, then operation of control means 56B could 
be modified to increase the flow of air discharged from nozzle 50B and to 
divert more of veil 48B toward the right hand side of the collection 
surface. Each of the control means can be coordinated by means not shown 
to effectively control the distribution of fibers on the collection 
surface. The operation of the control means can be in response to sensing 
means, not shown, for determining deviations from desired fiber 
distribution patterns. 
EXPLOITATION IN INDUSTRY 
This invention will be found to be useful in the formation of fibers from 
molten glass for such uses as glass fiber thermal insulation products and 
glass fiber acoustical insulation products.