U.S. patent number RE31,775 [Application Number 06/273,040] was granted by the patent office on 1984-12-25 for method and an apparatus for distributing a disintegrated material onto a layer forming surface.
This patent grant is currently assigned to Scan-Web I/S. Invention is credited to Torsten B. Persson.
United States Patent |
RE31,775 |
Persson |
December 25, 1984 |
Method and an apparatus for distributing a disintegrated material
onto a layer forming surface
Abstract
A method and an apparatus for distributing loose fibers or
particles onto a moving web in an even layer thereon preparatory to
production of a non-woven sheet of the fiber or particle material.
The material is filled into a container having a generally V-shaped
screen bottom extending crosswise over the moving web, and whipping
members are rotated in the bottom space so as to whip the material
adjacent the interior surface of the screen by a whipping movement
causing the fibers or particles to be slung against the screen and
the material to move in a flow lengthwise along the bottom
surfaces, whereby when suction is applied to the outside of the
screen bottom through the web the fibers or particles will get
dispensed through the screen and deposited on the web. The combined
shipping and slinging of the material contributes to a high
capacity of the distribution.
Inventors: |
Persson; Torsten B. (Maarslet,
DK) |
Assignee: |
Scan-Web I/S (Risskov,
DK)
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Family
ID: |
27259290 |
Appl.
No.: |
06/273,040 |
Filed: |
June 12, 1981 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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717384 |
Aug 24, 1976 |
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Reissue of: |
862035 |
Dec 19, 1977 |
04157724 |
Jun 12, 1979 |
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Foreign Application Priority Data
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Aug 27, 1975 [GB] |
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35429/75 |
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Current U.S.
Class: |
141/1; 141/11;
141/131; 19/304; 264/122; 425/83.1 |
Current CPC
Class: |
D04H
1/732 (20130101) |
Current International
Class: |
B65B 001/14 () |
Field of
Search: |
;141/1,67,129,131
;427/183,294,348 ;425/80.1,81.1,82.1,83.1 ;19/304-308
;264/87,121-123,DIG.75 ;162/292 ;65/9 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Bell, Jr.; Houston S.
Attorney, Agent or Firm: Antonelli, Terry & Wands
Parent Case Text
This is a continuation of application Ser. No. 717,384, filed Aug.
24, 1976, now abandoned.
Claims
What is claimed is:
1. Apparatus for depositing and distributing loose fibres or
particles onto a surface of a moving carrier web comprising:
(a) a housing having inlet and outlet ends;
(b) a moving carrier web having a surface positioned adjacent the
outlet end of said housing;
(c) screen means within said housing between said inlet and outlet
ends, at least part of said screen means being arranged so as to
extend in a manner which is transverse and non-parallel with
respect to the surface of the moving carrier web;
(d) agitator means within said housing for creating a flow of said
particles or fibres about an axis extending between said inlet and
outlet ends, and for directing said particles or fibres outwardly
against and through .Iadd.said part of said .Iaddend.said screen
means; and
(e) means for directing particles or fibres passing through said
screen means to said moving carrier web whereby said particles or
fibres are deposited in a layer upon said moving carrier web.
2. Apparatus according to claim 1, wherein said agitator means
includes a plurality of agitating members, said agitating members
being positioned in spaced areas along the screen means for causing
said material to move in a flow, relatively slowly, with respect to
the speed of the agitating members, from one area to an adjacent
area.
3. An apparatus according to claim 2, in which the housing is
elongated crosswise of said moving carrier web and is provided with
one row of said agitating members, the part of the screen means
which extend transversely and non-parallel with respect to the
moving carrier web being located at both sides of said row.
4. Apparatus according to claim 2, characterized in that the
whipping is effected by whip members which are rotated in a plane
of rotation which intersects said part of the screen means which is
transverse and non-parallel to the carrier web.
5. An apparatus according to claim 4, wherein the agitating members
are mounted in a stationary row along the screen means and are
provided with thin whip elements, the outermost portions of which
pass closely along portions of the transversely and non-parallel
extending part of said screen means and move in a plane of rotation
which is non-parallel to the respective screen portions, all whip
members being rotated in a uniform direction of rotation.
6. An apparatus according to claim 5, in which the whip elements
project radially from shafts of the agitating members and in which
at least some of the whip members of two adjacent agitators are
axially offset from each other and mounted so as to rotate in
overlapping circular paths.
7. An apparatus according to claim 5, in which the whip elements
are constituted by radially projecting rods of flat cross
section.
8. An apparatus according to claim 7, in which the rods have
opposed surfaces which taper towards each other at least adjacent
leading edges of the rods.
9. Apparatus according to claim 1, characterized in that said
agitating members are rotary whip members which are rotated in a
plane of rotation which intersects said part of the screen means
which is transverse and non-parallel to the carrier web.
10. Apparatus according to claim 9, wherein said agitating members
have plural whipping elements which whip said fibres or particles,
as they rotate about a respective axis, in a manner causing
disturbance of the fibres or particles without to any substantial
degree causing the material to move with the whipping elements
about their respective axis of rotation.
11. An apparatus according to claim 1, wherein said screen means is
provided with a bottom having a lower flat portion located above
and parallel with the moving carrier web and outer inclined side
portions, and wherein the agitator means includes whip members
arranged so as to form a correspondingly frusto-conical
pattern.
12. An apparatus according to claim 1, in which the housing
includes wall portions arranged so as to confine a space between
said part of the screen means and the moving carrier web, said
space communicating with air intake means for external air.
13. Apparatus according to claim 1, wherein said agitator means
comprises a plurality of whip members spaced radially and axially
along a rotatable shaft, said whip members being positioned within
said container so as to enable all of said whip members to pass in
close proximity to said screen.
14. Apparatus according to claim 1, wherein said means for
directing comprises a wall member of said housing arranged about
said screen means so as to form a space communicating an air intake
with said carrier web externally of said screen.
15. Apparatus according to claim 1, wherein said means for
directing comprises suction means for drawing the fibre or particle
material through said screen means.
16. Apparatus according to claim 15, wherein said moving carrier
web is foraminous and said suction means includes a suction box
disposed on a side of said moving carrier web which is opposite
from the surface adjacent said housing outlet.
17. A method for depositing and distributing loose fibre or
particle material onto a surface of a moving carrier web comprising
the steps of:
(a) feeding the loose fibre or particle material into a housing
having inlet and outlet ends, the outlet end being positioned
adjacent a surface of a moving carrier web;
(b) agitating said material within said housing by creating a flow
of said material about an axis extending between the inlet and
outlet ends of the housing and directing said material outwardly
against a screen means which is located in said housing and at
least in part extends in a manner which is transverse and
non-parallel to said surface of the moving carrier web and through
.Iadd.said part of said .Iaddend.said screen means; and
(c) directing material passing through the screen means to said
moveable carrier web so that said material is deposited in a layer
upon the surface of the moving carrier web.
18. A method according to claim 17, wherein the step of agitating
is performed by a plurality of rotary agitating members positioned
along spaced areas of the screen means and wherein the material is
caused to move in a flow, relatively slowly in comparison to the
speed of the agitating members from one area to an adjacent
area.
19. A method according to claim 18, wherein the step of agitating
is performed by causing a disturbance of the material without to
any substantial degree causing the material to move with the rotary
agitating members about their respective axis of rotation.
20. A method according to claim 18, wherein the material is
directed through the screen means at least in part by suction.
21. A method according to claim 20, wherein the step of directing
the fibre of particle material through said screen means by suction
is performed by a suction box disposed beneath said carrier web
drawing air through said housing, screen means, and carrier web.
.Iadd.
22. Apparatus for distributing and depositing loose fibers or
particles onto a surface of a moving carrier web comprising:
(a) a foraminous moving carrier web;
(b) a distributor housing having an outlet positioned above said
carrier web;
(c) screen means within said housing for screening a flow of said
fibers or particles therethrough prior to their being discharged
from said outlet onto said carrier web;
(d) flow producing means within said housing, upstream of said
screen means, for creating a flow of fibers or particles
circulating within said housing and as a whole traveling
transversely across said screen means and a line of movement of the
moving carrier web and for creating said flow of fibers or
particles through said screen means outwardly therefrom; and
(e) suction means below said carrier web for drawing said fibers or
particles from said outlet onto said carrier web. .Iaddend.
.Iadd.23. Apparatus according to claim 22, wherein said flow
producing means is an agitator means. .Iaddend. .Iadd.24. Apparatus
according to claim 23, wherein said agitator means comprises at
least one shaft mounted for rotation about a substantially
horizontal axis and a plurality of impellors extending therefrom,
some of said impellors being shaped to create a flow longitudinally
relative to said shaft for producing said flow transversely across
said screen means. .Iaddend. .Iadd.25. Apparatus according to claim
22 or 24, wherein said flow producing means comprises a plurality
of agitator means, a first of said agitator means producing said
flow transversely across said screen means in a first direction and
a second of said agitator means producing said flow transversely
across said screen means in an opposite direction, and together
said agitator means acting to cause said flow transversely across
said screen means to circulate in a path around in said housing.
.Iaddend. .Iadd.26. Method for distributing and depositing loose
fibers or particles comprising the steps of:
(a) feeding loose fibers or particles into a distributor housing
having an outlet positioned above a foraminous moving carrier
web;
(b) creating a flow of said particles or fibers circulating within
said housing and as a whole traveling transversely across both a
screen means positioned for screening a flow of said particles and
fibers outwardly therethrough and a line of movement of said
carrier web, and applying outwardly directed forces to said
transverse flow for creating said flow through said screen means;
and
(c) drawing said fibers or particles, flowing outwardly through
said screen means, onto said carrier web so as to be deposited in a
layer thereon. .Iaddend. .Iadd.27. Method according to claim 26,
wherein said creating steps are performed by agitator means within
said housing upstream of said screen means. .Iaddend. .Iadd.28.
Method according to claim 27, wherein said agitator means is caused
to rotate about a substantially horizontal
axis. .Iaddend. .Iadd.29. Apparatus for distributing and depositing
loose fibers or particles onto a surface of a moving carrier web
comprising:
(a) a foraminous moving carrier web;
(b) a distributor housing having an outlet positioned above said
carrier web;
(c) screen means within said housing for screening a flow of fibers
or particles therethrough prior to their being discharged from said
outlet onto said carrier web said screen means being elongated in a
direction substantially parallel to with the surface of the moving
carrier web;
(d) flow producing means within said housing, upstream of said
screen means, for creating a flow of fibers or particles
circulating within said housing and as a whole traveling
transversely across said screen means in said direction of
elongation substantially parallel to the surface of the moving
carrier web and for creating said flow of fibers or particles
through said screen means outwardly therefrom; and
(e) suction means below said carrier web for drawing said fibers or
particles from said outlet onto said carrier web. .Iaddend.
.Iadd.30. Apparatus according to claim 29, wherein said flow
producing means is an agitator means. .Iaddend. .Iadd.31. Apparatus
according to claim 30, wherein said agitator means comprises at
least one shaft mounted for rotation about a substantially
horizontal axis and a plurality of impellors extending therefrom,
some of said impellors being shaped to create a flow longitudinally
relative to said shaft for producing said flow transversely across
said screen means in said direction of
elongation. .Iaddend. .Iadd.32. Apparatus according to claim 31,
wherein said shaft extends in said direction of elongation and each
of said impellors rotates in a plane that intersects said screen
means. .Iaddend. .Iadd.33. Apparatus according to claim 29 or 30,
wherein said flow producing means comprises a plurality of agitator
means, a first of said agitator means producing said flow
transversely across said screen means in a fist direction of
elongation and a second of said agitator means producing said flow
transversely across said screen means in an opposite direction of
elongation and together said agitator means acting to cause said
flow transversely across said screen means to circulate in a path
around in said housing. .Iaddend. .Iadd.34. Apparatus according to
claim 29, wherein said housing is provided with outer wall portions
disposed on an exterior side of portions of said screen means that
extend in a generally non-parallel manner with respect to the
surface of the moving carrier web, said outer wall and screen means
portions defining an air duct having an upper air intake end and a
lower end communicating with said housing outlet, whereby both said
outward flow of fibers or particles and a scavenging air flow pass
through said air duct. .Iaddend. .Iadd.35. Method for distributing
and depositing loose fibers or particles onto a surface of a moving
carrier web comprising the steps of:
(a) feeding loose fibers or particles into a distributor housing
having an outlet positioned above a foraminous moving carrier
web;
(b) creating a flow of said particles or fibers circulating within
said housing and as a whole traveling across a screen means that is
elongated in a direction substantially parallel the surface of the
moving carrier web and positioned for screening a flow of said
particles and fibers outwardly therethrough in said direction of
elongation parallel to the surface of said carrier web, and
applying outwardly directed forces to said transverse flow for
creating said flow through said screen means; and
(c) drawing said fibers or particles, flowing outwardly through
said screen means, onto said carrier web so as to be deposited in a
layer thereon. .Iaddend. .Iadd.36. Method according to claim 35,
wherein said creating steps are performed by agitator means within
said housing upstream of said screen means. .Iaddend. .Iadd.37.
Method according to claim 36, wherein said agitator means is caused
to rotate about a substantially horizontal axis. .Iaddend.
.Iadd.38. Method according to claim 37, wherein said agitator means
comprises a plurality of rotary shafts each having a plurality of
impellors, some of said impellors on each shaft being shaped to
create a flow longitudinally of said shaft, said agitator means
being operated to cause said flow transversely across the screen
means to circulate in a path around in said housing. .Iaddend.
.Iadd.39. Method according to claim 28, wherein said agitator means
comprises a plurality of rotary shafts each having a plurality of
impellors, some of said impellors on each shaft being shaped to
create a flow longitudinally of said shaft, said agitator means
being operated to cause said flow transversely across the screen
means to circulate in a path around in said
housing. .Iaddend. .Iadd.40. An apparatus for distributing loose
fibers or particles onto a moved foraminous sheet, comprising:
A distributor container located overhead said foraminous sheet and
having an inlet for fiber or particle material to be distributed
and a perforated outlet wall portion, through which the material is
dispensable to a space outside an exterior side of the outlet wall
portion,
means for creating a flow of air through the foraminous sheet, by
suction from beneath the sheet, in an area generally underneath the
said space outside of the outlet wall portion to thereby cause the
material as dispensed through said outlet wall portion to be
carried towards and be deposited on the foraminous sheet,
said perforated outlet wall portion being elongate generally in a
first direction, which is substantially parallel with the surface
of the foraminous sheet;
agitator means located inside said distributor container for
agitating the material and keeping it air fluidized therein,
means for creating a unidirectional, primary flow of the air
fluidized material along the interior side of the outlet wall
portion substantially in said first direction thereof, from an
upstream end to a downstream end of the wall,
means for continually guiding said flow of air fluidized material
back from said downstream end to said upstream end of the outlet
wall portion along a path spaced from said primary flow for
recirculation of the material flow,
said inlet of the distributor container communicating with the path
of said material flow to enable supply of material thereto; and
deviator means, forming part of said agitator means, located inside
said container operable to impart to the said primary material flow
or selected portions thereof a velocity component directed
outwardly through said outlet wall, thereby to promote material
dispensing through said outlet wall. .Iaddend. .Iadd.41. An
apparatus according to claim 40, in which said deviator means
comprise power driven impeller members located in one or more rows
extending along the outlet wall portion in said first direction
thereof, each of said impeller members rotating in a plane
intersecting the outlet wall portion. .Iaddend.
Description
The present invention relates to a method of distributing loose
fibres or particles onto a carrier surface constituted by a carrier
web, by filling the fibre or particle material into a container
having a screen wall portion located adjacent one side of said
carrier web, agitating the material violently and creating an air
flow through the material and through the said screen and web by
sucking air from the other side of the web so as to cause the
fibres or particles to gradually penetrate the screen and get
deposited in a layer on the moving carrier web.
A method of this type and an apparatus for carrying out the method
is disclosed in the British patent specification No. 1,207,556
.Iadd.(corresponding to U.S. Patent No. 3,581,706). .Iaddend.The
fibre material is filled into a circular cylindric vat having a
plane, perforated bottom constituting the said screen wall portion
and located parallel and close to the underlying, moving carrier
web. For the agitation of the material near the screen bottom is
used a stirring device comprising two vertical rotor shafts mounted
in a planet gear arrangement overhead the vat and at their lower
ends, just above the screen bottom, provided with radial,
vertically oriented impeller fins or blades whirling around in the
bottom material layer. Underneath the vat and the moving web is
arranged a suction box which draws an air flow through the material
in the vat and through the screen bottom and the web, whereby the
disintegrated fibres near the bottom are drawn out and deposited on
the moving web in a reasonably even layer thereon. The web moves
the layer to a binding and curing station in which the layer is
made into a non-woven sheet material for one of a wide variety of
purposes.
By the agitation of the fibre material it is aimed to ensure that
the fibres are kept mixed with the air and are caused to be
repeatedly rearranged with respect to the adjoining fibres, whereby
they will sooner or later get the opportunity to pass through the
fine holes in the screen together with the suction air. The degree
of rearrangement of the fibres is highest where the blade edge
velocity is highest, i.e. an effective agitation is obtained in an
annular area adjacent the outer blade edge portions. However, due
to the centrifugal forces which tend to blow the material away from
this area, it can be observed that for increasing impeller speed
the dispensing capacity of the apparatus increases only to a
certain point, whereafter it decreases, and in fact the obtainable
maximum capacity is not as high as could be desirable.
According to another known method the fibre material is fed to the
cylindric space between a lying rotating drum and a screen shell,
the drum carrying a high number of radially protruding needles
which serve to disintegrate and rearrange the fibre material.
However, the material tends to be moved rapidly through the said
space along with the drum surface, and hereby the velocity of the
needles relative to the material is not by far as high as the
absolute needle velocity, and the ability of the needles to cause
rearrangement of the fibres, therefore, and therewith the
dispensing capacity is correspondingly relatively low.
It is the purpose of this invention to provide a method whereby a
high dispensing capacity is achieved in a simple manner.
According to the invention the material in the container is
agitated by whipping it immediately inside the said screen wall
portion. The term "whipping" as used here and in the following and
in the appended claims is intended to be indicative of the act of
repeatingly moving through the material to be whipped a relatively
narrow beat member having proportions so as to cause disturbance in
the configuration of submatters of the material along the moving
path of the beat or whip member through the material, without to
any substantial degree causing the material to move in the beating
direction, such that the submatters along the moving path of the
beat member are vividly separated and displaced. When a dry fibrous
or otherwise loose material is whipped in this manner in air the
fibres or particles are kept in air fluidized condition, and the
whipping involves a high degree of rearrangement of the fibres or
particles without forcing these to move along with the whip or beat
members, and consequently the fibres or particles are readily
sucked out through the holes in the screen wall portion, whereby a
high dispensing capacity in ensured. An increased whipping speed
primarily involves an increased rate of rearrangement of the fibres
or particles and therewith an increased dispensing capacity within
wide limits.
In partice it may be troublesome to effect whipping of the material
adjacent all surface portions of the screen wall of the container,
but tests have shown that excellent results are obtainable if the
whipping is effected in spaced areas along the screen wall and the
material is caused to be moved, relatively slowly, from one
whipping area to the next. Once whipped the material remains in its
air fluidized condition for some time, and if the whipping is
repeated soon thereafter by virtue of the material being moved to
the next whipping station along the screen the fibres or particles
even in the material flow between the whipping stations will be
readily dispensable through the screen holes.
The said movement of the material from one whipping station to the
next and so forth is easily obtainable by means of the whipping
members themselves, when they are moved in a unidirectional manner
adjacent the screen so as to cause a general, relatively slow
material movement therealong. This movement may well be rapid, in
an absolute sense, but far less rapid than the velocity of the
whipping members.
The invention further comprises an apparatus for carrying out the
described method, as defined in the appended claims and as
described in more detail below.
It should be mentioned already here that a very important aspect of
the invention is the provision of rotary whip members which rotate
in a plane non-parallel to the screen wall portion, whereby the
whip members cause the material to be slung against the screen and
therewith promote the penetration of the fibres or particles
through the screen wall. The agitators may be mounted in a
stationary manner, and the fast moving peripheral whip member
portions may pass closely along a screen area without the remaining
member portions, moving with smaller speed, being moved closely
along the screen, whereby they might cause the fibre material to
flocculate by rolling it rather than whipping it.
By way of example the invention will now be described in more
detail with reference to the accompanying drawing, in which:
FIG. 1 is a side elevation, partly in section, of an apparatus
according to a preferred embodiment of the invention,
FIG. 2 is a cross sectional side view of this apparatus,
FIG. 3 is a detail of FIGS. 1 and 2 as seen from above,
FIG. 4 is a sectional perspective view of FIG. 1,
FIG. 5 is a view of a modified detail,
FIG. 6 is a general view of a modified apparatus according to the
invention, and
FIG. 7 is a transverse cross-sectional view of one form of
agitating member according to the invention.
FIG. 1 shows an elongated fibre distributor container generally
designated 1 and shaped with half-rounded end portions 2, each of
which having a vertical, cylindric upper portion 9 and a downwardly
projecting bottom portion 6 of conical shape and a horizontal,
half-circular bottom plate 8. The end portions 2 are interconnected
by means of vertical side plates 10 between the upper portions 9,
and these parts 2-10 are made of non-perforated metal sheet
material. Between the side plates 10 and the end portions 6 and 8
there is mounted a screen as a whole designated 12 and penetratable
by fibres and air and being of U-shaped cross section corresponding
to the end portions 2, i.e. showing a plane horizontal bottom
screen portion 14 and two slanting screen portions 16. The
container 1 is supported by means of columns 18 crosswise above a
horizontal fibre layer forming web consisting of a finely meshed
screen or wire netting 20 which is endlessly drawn about rollers 22
and driven by means of a drive station (not shown) in the direction
shown by an arrow. A suction box 24 having an exhauster 26 is
arranged beneath the screen 12 and the wire netting 20 and
supported by means of beams 19 connected onto the columns 18. The
suction box is closed in the bottom portion and the sides and has
an upper opening 28 located close to the underside of the web 20,
sealed thereagainst by means of sealing flanges 30. The suction box
is in one side provided with a horizontal slide gate 32 having a
curved edge portion 34 for controlling the suction area, as
described in more detail below. At one end portion 4 there is
provided a bracket 36 supporting a motor 38, which by means of a
chain drive 40 drives four vertical axles 42 running in bearings 44
which are mounted onto cross bares 46 which again are supported at
the side plates 10. The axles 42 are arranged in a row in the
vertical plane of symmetry of the container and each provided with
three pairs of diametrically opposed and radially mounted flat,
elongated rotor members 48, the lengths of which are adapted in
such a way that their tip portions during rotation will sweep areas
of the slanting screens 16 in short distance, and further the
lowermost rotor members are arranged just above the bottom screen
14. The lowermost rotor members are situated so as to rotate in a
common horizontal plane above the bottom screen 14, while the other
rotor members are offset and arranged so as to rotate in areas
partly overlapping each other.
Along its broad sides the container is provided with exterior wall
plates 50 which together with the side plates 10 form a scavenging
channel 52 closed at the sides by plate members 54. The wall plates
50 and the plate members 54 reach down closely above the netting 20
and confines a generally triangular space between the slanting
bottom screen 16 and the netting 20, which space is shielded from
the surrounding air except for the upper opening of the scavenging
channel 52. The wall plate 50 has a right angular bending at the
lower edge forming an air sluice 56 through which the netting can
pass carrying a layer of fibres deposited thereon as described
below.
In operation the axles 42 are rotated in the same direction by
which the tips of the rotor members are moved at a velocity in the
region of 50 meters per second. This speed is suitable for the
treating of e.g. cellulosic fibres, but should be adapted according
to the desired product and may vary within wide limitations. An
airflow is created through the bottom screens 14,16 via the netting
20, the suction box and out through the exhauster 26. In the same
manner air is sucked through the scavenging channels 52. A
disintegrated material e.g. cellulosic fibre pulp is fed to the
container through a fibre spreading inlet 58 up to approximately
the level of the uppermost rotor members and agitated by means of
the fast rotating members 48, which will thereby whip violently
through the material. By the unidirectional rotation of the rotor
members the fibre material is generally thrown against the opposed
slanting screen walls 16, whereby the material profile will be
somewhat as indicated by a dotted line a in FIG. 2. The material
supported by the slanting screen walls is forced by the rotor
members 48 to move along the respective walls so as to generally
move relatively slowly in a flow around in the container along the
sides and ends thereof. The fibres hereby passing the areas swept
by the rotor members are vividly whipped and rearranged, and they
maintain their state of being fluidized until with said flow they
reach the next whipping area. Thus, the slanting bottom screens 16
and the outer edge portions of the bottom screen 14 are
continuously being swept by an effectively fluidized current of
fibres which can thus readily be sucked through the screens 14,16.
Having passed these screens the fibres will follow the suction air
and be deposited onto the netting 20 which separates the fibres
from the air thus forming a sheet of loose fibre material which by
the movement of the netting is carried through the sluice 56 for
fixation or other desired purposes.
Some of the fibres are liable to adhere to the inner side of the
outer wall 50,54, but are prevented from this by means of the
scavenging air flowing down along the inner side of these walls
after being oriented in the channel 52. Sucking some air this way
towards the netting implies the advantage that possible areas of
smaller thickness of the fibre layer on the netting has a tendency
to be filled so as to show the desired evenness of the sheet of
loose fibres, since more air will pass through the thinner areas
than through the thicker areas, whereby more fibres will be
directed from the upper dispersing zone adjacent the screen 16
towards the thinner areas in a concentration higher than generally
found above the sheet. In this manner, should the fibres be
dispensed at an increased rate from the screen portions adjacent
the areas swept closely by the tips of the rotor members, the
resulting uneven distribution of the fibres will thus be
counteracted. It will be noted that the longest way of fibre
passage from the screen to the netting is from the upper screen
portions, i.e. the portions located near the highest speed area of
the rotor member tips, i.e. the most active areas of fibre
dispensing.
The flow of fibre material inside the container is turned at either
end sections 2 and thrown around and upwardly along the half cones
of the bottom portion 6 entering the area adjacent the ends of the
cylindrical portion 9 from where the material is guided by means of
guide plate members 60 down again along the lengthwise side
portions and so forth. During the turning of the flow of material
heavy particles or possible clusters of fibres or other scrap
matters will concentrate in the area above the cone at the
periphery, where they may be removed. For this purpose there is
provided a tangential outlet pipe 62 the entrance of which is a
horizontal slot partly covered by a slidably mounted plate member
64 for adjusting the height of the slot so as to control the outlet
of e.g. scrap matters. It is possible to connect the outlet pipe 62
to recycle means in well known manner.
The rotor members 48 may have any of a variety of shapes for
carrying out their whipping function, e.g. as shown in FIG. 5,
where 42 designates the lower end of the axle 4 shown in the
previous figures to which there is mounted two horizontal arm
members 48' similar to the rotor members 48, but at the outer ends
being interconnected by means of two inclined whip members 49. In
this case the axles 4 should be spaced from each other so as to
permit unidirectional rotation. Preferably the rotor members 48
should have more or less sharpened front edges 45, while the rear
edges 47 can be flat as shown in FIG. 7 or the rear edges can be
shaped or provided with flap members so as to enforce an
aerodynamic turbulence, facilitating the fluidizing of the
fibres.
The apparatus should not necessarily be provided with three screens
14,16 of equal mesh, since by diligent choice of screen types it is
possible to form a sheet of loose fibres consisting of e.g. two
outer layers of one type of fibres and a midlayer of another type,
the different types of fibres being sorted by means of the chosen
types of screens. Tests have shown that the apparatus is usable
even for fibres longer than these normally treated by apparatuses
of the type considered.
FIG. 6 shown a modified embodiment in which the agitators are
mounted for rotation about horizontal axles. The numerals
indicating parts in the previous figures indicates equivalent means
in FIG. 6. The container 1 is furnished with a modified bottom
portion having a screen 15 the cross section of which is U-shaped
with a straight bottom portion. Parallel to this there is arranged
two horizontal axles 5 on each of which there is mounted a set of
rotor members 148 arranged so as to rotate by means of the motor
drive 38,40, each of the tips of the members 148 sweeping an area
close to the screen 15 at a right angle to this. As indicated with
rounded tip ends some of the impellers, designated 51, are shaped
slightly like a propeller so as to create a general flow of fibres
longitudinally along the curved sides of the screen 15 in one
direction along one side and in the opposite direction along the
other side. Thus, the impellers serve the combined purpose of
whipping the material and moving it around in the container.
A very important feature of the invention, common to both the
apparatuses shown in FIGS. 4 and 6, is that the impellers are
arranged so as to rotate in a plane non-parallel to the plane of
the screens 15,16, the tips being close to these so as to maintain
a zone of effectively fluidized fibres directed by means of the
centrifugal forces towards the screen portions 15,16 generally in
the direction in which the fibres will readily pass the screens. A
feature also common for the two examples as the general flow of
disintegrated material along the inner side of the screen portions
15,16 so as to facilitate an even output of fibres through the
screens 15,16.
The container 1 should preferably, but not necessarily be covered
by a lid section (not shown) of screen material permitting an
escape of excess air if the fibres are fed through the fishtail
inlet 58 by means of transport air exceeding the amount of air
being sucked via the exhauster 26, but keeping the fibres within
the container.
The amount of fibres in the container 1 is controlled by
controlling the rate of input in accordance with the output rate so
as to maintain a constant profile of the fibre flow along the
screens. However, experiments have surprisingly shown that it is
possible to produce a sheet of evenly distributed fibres without
maintaining said constant profile; it is in fact possible to feed
the fibres botchwise into the container and still obtain even
layers of fibres on the netting until the container is run
practically empty, which is an outstanding advantage of the
invention.
The whip members may be of any suitable design, e.g. constituted by
wire members, and they may be arranged for rotation in any suitable
manner such that the tip portions thereof are moved repeatedly
towards and away from the screen portion cooperating with the whip
member.
The slide gate 32 for controlling the suction area may be
subdivided into sections as indicated with dotted lines in FIG. 3.
The sections may then be individually operated so as to adjust the
shape of the suction area 28 and in this way control possible
variations of the thickness across the sheet of loose fibres, i.e.
if the sheet should be provided with a longitudinal zone in which
the layer of fibres is thicker or thinner, the section or sections
beneath the zone should be positioned so as to increase or decrease
respectively the suction area in question. By .[.continuos.].
.Iadd.continuous .Iaddend.operation during a longer period of time
parts of the screen may be clogged up or choked by fibres or
foreign matters, whereby a thinner zone of the sheet may be
produced. This can be counteracted by means of the individually
operable gate sections and may be controlled by automatic means. It
will be appreciated that this method of controlling the thickness
of a sheet material formed by suction not only is suitable for
correcting the uniformity of the cross section of the sheet, but
also can be used advantageously as a control means for the
thickness of the sheet in general. This thickness control means may
further be used in connections other than that of the present
invention, i.e. where a submatters of a material is deposited on a
forming surface by means of suction.
It should be noted that the slanting screen walls should preferably
be provided with the perforations showing free openings as seen in
the direction of the centrifugal forces of the rotor members, thus
facilitating the penetration of the fibres through the screen. A
minor disadvantage of this would be that some fibres were directed
directly towards the inner surface of the exterior wall plate 50,
so as to build up upon these and give rise to the risk of clumps of
articles falling down upon the the sheet of fibres, but this risk
is counteracted by means of the scavenging current through the
channel 52. Another way of overcoming this problem could be the
substituting of the wall plate 50 by a horizontal roller covering
with part of its surface the triangular space between the screen 16
and the web. In this way the fibres deposited upon the roller
surface can be continuosly removed and the scavenging channel 52
and the sluice 56 may be omitted.
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