Note: Descriptions are shown in the official language in which they were submitted.
1036781
MACHINE FOR FORMING RANDOM FIBER WEBS
The present invention relates to machines for forming
random fiber webs, and more particularly to such machines in
which a fiber mat is fed to a rotating lickerin, which combs
individual fibers from the matj and the fibers are doffed from
the lickerin by centrifugal force and by an air stream flowing
tan~entially past the lickerin, and the doffed fibers are carried
in suspenslon in the air stream to a moving foraminate condenser,
on which the fibers are deposited in random fashion to form the
random or non-woven fiber web. The webs are suitable for pro-
ducing high quality non-woven fabrics by known chemical or
mechanical bonding treatments.
Because the duct between the lickerin and the condenser
is generally horizontal, prior machines of the type described are
generally horizontal in their ma;or direction, and occupy
considerable floor space. If a fiber feeder is attached to the
web forming machine, as is generally the case nowadays in
practice, the amount of floor space occupied by the combination-
feeder-webber is quite considerable; and floor space is expensive.
Non-woven fabrics are produced from web structures by
chemically bonding or by mechanically interlocking the fibers
together. The dry formed structures may be chemicall-y bonded by
known means such as the application of adhesives by spray or by
saturation, also bonding may be accomplished by the use of
fibers which have a low melting point and form a bond to non-
adhesive fibers by heat and pressure. Mechanical bonding may be
carried out by needling, or stitch bonding may be usedj also
apertured or print bonding may be used to provide strength and
durability. The quality of any non-woven fabric produced by
these finishing methods depends upon the quality and uniformity
of the web structure which is to be treated or finished.
Webs suitable for producing random non-woven web struc-
ture have been prepared by aerodynamic formation apparatus s~h
~ ;
,.. ~,; ' ,
1036781
as manufactured by Rando Machine Corporation and known as
"Rando-Webbers" and disclosed in Canadian Patents 465,052,
530,645, 564,713, 864,756, 853,403 and 930,518.
Non-woven web structures formed by aerodynamic means are
normally produced by opening and blend~ng various fibers to
separate the fibrous mass into individual fibers. The opened
fibers are formed into a uniform feed mat. The opening and the
formation of the feed mat are extremely important to the final
web structure since any non-uniformity or poor opening will
caus~ unwanted ~rregularlties in the final product.
The uni~orm feed mat is fed via a toothed or clothed
feed roll to a similarly covered lickerin, and a stream of air
is caused to move over the surface of this lickerin by either a
positive or negative air pressure. The lickerin i5 rotated at
high speed to feed or comb the fibers from the feed mat into the
air stream, the ob;ective being to feed individual fibers rather
than clumps or groups of fibers. The fibers are carried in the
machines of the present invention by the high velocity air
stream as a dilute dispersion downwards through a vertical con-
duit to a condensing screen surface moving at right angles tothe flow in the vertical path, and are deposited over a relatively
large surface area to form a random structure on the moving
screen.
The primary ob~ect of the present invention is to provide
an aerodynamic process and apparatus suitable for hlgh speed pro-
duction of uniform webs of excellent quality from uniform feed
mats made of fibrous materials.
Another object of the present invention is to provide a
web forming machine which will be more compact than prior such
machines, and which will occupy a minimum of floor space.
Another ob~ect of the invention is to provide a combina-
tion fiber feeder and webber, which together will be much more
compact than prior such combinations.
103678~
Other objects of the invention will be apparent herein-
after from the specification and from the recital of the
appended claims~ particularly when read in conjunction with the
accompanying drawings.
In the drawings:
Fig. 1 is a somewhat diagrammatic vertical sectional
view of a combination fiber feeding and web form~n~ machine
built according to one embodiment of this invention;
Fig, 2 is a vertical sectional view on an enlarged scale
illustrating further the condenser fan section of the machine;
Fig, 3 is a fragmentary sectional view at right angles
to the view of Fig. 2;
Fig. 4 is a vertical sectional view on the scale of
Fig, 2 showing the lickerin and the duct for conveying fibers
from the lickerin to the webber condenser of the machine;
Fig, 5 is an enlarged side elevation of the main fan
duct section of the machine, parts being broken away;
Fig, 6 is a somewhat diagrammatic vertical longitudinal
sectional view of a combination fiber feeding and web-forming
machine built according to a second embodiment of the invention;
Fig, 7 is a section through this machine taken on the
line 7-7 of Fig, 6; and
Fig, 8 is a greatly enlarged fragmentary view showing
the feed roll, feed plate, lickerin, pressure air chamber and
doffing bar of this machine,
The present invention is an improvement in forming webs
of fibrous material over the apparatus disclosed in Canadian
Patent No. 930,518 by dispersing fibers in a flow of air or gas
which acts in a downwards direction acting with the pull of
gravity and then, collecting the fibers on a horizontal moving
condenser screen whose direction is at right angles to the air
and fiber flow to form a random arrangement of the fibrous web
structure, 3
1036781
In accordance with this improvement the fibrous particles
(which may be for instance~ staple textlle fibers or natural
fibers of wool, cotton or wood) are projected at a uniform
initial velocity of at least 4500 feet per minute and preferably
between 10,000 and 20,000 feet per minute at a vertical or
perpendicular angle to the forming screen and through an expan-
sion chamber which is somewhat rectangular in cross-sectlon with
two walls havin$ an angle of less than 15 degrees and preferably
less than 11 degrees from each other and two walls having not
more than 5 degrees from their vertical and preferably 3 degrees
or less such that this expansion chamber increases in its cross-
section from the lickerin to the condenser screen.
The flow of air or gas is controlled so that the fibrous
particles are projected into a region of stable flow character-
ized immediately upstream of the fiber flow by a combination of
an average velocity of the air flow (V) of between 0.25 and 1.5
times the initial fiber velocity and preferably between 0.5 and
1,2 of that velocity.
The fibers are preferably projected onto the condenser
screen at a rate of between 5 and 25 pounds per hour per inch
of machine width of air flow width, although the apparatus is
suitable for slow and higher rates of operation. The weight rate
of air flow ls usually determined by the formula disclosed in
the Wood U, S. Patent 3,535,187 and is dependent upon the amount
of fibers and their weight and size.
The air flow conditions are controlled to provide a
relatively thin fibrous stream which may be less than 6 mm thick
as initially formed and preferably less than 3 mm thick. The
thickness of the downwards acting fiber stream increases some-
what as the flow passes through the expansion chamber butshould not expand to more than 12 to 25 mrn thick as it approach-
es the condensing surface.
The fibrous particles are given their initial velocity
1036781
by the centrifugal force of the lickerin and e;ected into the
path of the air stream at a tangential to the lickerin and
vertically downwards to the surface of the lickerin cylinder
into the path of the air flow.
The surface speed of the lickerin should be at least
4500 feet per minute and the preferred surface speed for staple
te~tile fibers is between 10 and 20,000 feet per minute,
although for wood fibers speeds of 20,000 feet per minute or
more may be necessary.
The feeding or supply means continuously provides a
uniform supply of fiber materials into the surface of the rotat-
ing lickerin and between a closely spaced curved tail of the nose
bar to hold the fiber close to the cylinder's surface until the
fiber enters the air stream and is doffed from the lickerin.
The fibrous material is thus projected downwards in a vertical
plane into the venturi section at the upper point of the expan-
sion chamber. The lickerin cylinder is mounted away from but
adjacent to the outer wall of the expansion chamber so that a
small arc of the surface of the cylinder is exposed within the
air flow and forms one side of the venturi at that point.
The inlet air flow duct directs a uniform velocity, low
turbulence, stable air stream, free from vorticities, in the
direction of movement of the lickerin cylinder and in a down-
wards direction making use of gravitational pressure, The
boundary layer which is formed around the surface of the lickerin
is interrupted by the use of a doffing bar which is incorporated
in the duct at a point of maximum shear just below the lickerin
and at the start of the expansion chamber to provide a controlled
low level of turbulence in the air layer through which the
fibrous particles must pass.
A conventional type of lickerin cylinder having its sur-
face covered with metallic card clothing having at least 25
polnts per square inch of surface area and preferably between
~o36781
50 and 80 points per square inch, is suitable for combing the
individual fibers from the feed mat and pro;ectihg these into
the air stream. The cùrved smooth surface of the tail of the
nose bar is arranged at a small distance from the surface of the
lickerin to provide a narrow passage where the fibers are carried
on the points of the wire covering or the cylinder surface to a
po~nt of pro~ection into the venturi and high velocity air stream.
The len~th of this curved section o~ the nose bar should form a
sector of a circle where the center is the pro;ected radius of
the lickerin plus the clearance or passage way so that the arc is
equal to
R ~ ~o Where R = the finished radius of the
lickerin plus the passage
way between the lickerin's
surface and the curved wall
of the tail of the nose bar.
(R pi ~o) pi =
1~0
cC o = the angle at the center of
the lickerin subtended by
the radius.
The angular distance 6~ should be between 15 and 40
and preferably between 17 and 37. The clearance between the
face of curved section of the nose bar tail and the tips of the
lickerin cylinder's teeth should be less than 0.020 inches and
preferably between 0.015 and 0.010 inch. The space between the
nose bar at the point where the apex of the nose bar approaches
~he lickerin surface should be less than 0,012 inch and pre-
~erably between 0.007 and 0.003 inch,
The surface speed of the lickerin is ~rom 4500 feet per
minute to ~n excess of 20,000 feet per minute; the surface speed
should be at the highest possible which does not damage the
f~bers being processed and the lickerin cylinder should be
designed for the surface speed, and balanced for minimum vibra-
tion, The cylinder's diameter should not be too large~ since
the fibers are pro~ected tangentially only a short distance
B
10367~1
before losing momentum, but a diameter of between 9 inches and
20 inches will be required to suit the required surface speed
and to reduce the vibration on wide machines~
The expansion chamber provides a conduit th~ough which a
uniform velocity, low turbulence flow of air is passed ad~acent
to the lickerin cyllnder and on to the fiber condenser screen.
The expansion chamber is o~ a con~iguration such that substan-
tially all the fibrous particles pro~ected from the feed means
are supported in the air stream which is a thin stream of less
than 6 mm and preferably less than 3 mm initial thickness, the
strea~ being kept away from layers of high turbulence, nonuni-
form flow, or separated flow.
Preferably the expansion chamber has a substantially
rectangular cross-section. The cross-sectional area increases
as the chamber approaches the condenser screen, the adverse
effects of boundary layer separation by the use of a too rapidly-
diverging duct is avoided by the use of the diffuser angles
between the walls in the widest cross-sectional direction of less
than 15 degrees and preferably less than 5 degrees from the
vertical for the other two walls. The chamber should be vertical
and at right angles to the condenser screen and without any
curvature from the pro~ection point to the condenser screen. The
fiber flow should be centered in the expansion chamber and
allowed to expand in a controlled manner to reduce the amount of
kinetic energy of the particles as they approach the condensing
surface.
In the preferred embodiment of the invention, the
inlet air duct is connected to a conventional air or gas supply
me~ns for providing an air flow of low turbulence intensity and
minimal eddies, The required air supply is normally via centri-
fugal fans blowing air into a highly uniform passage, which in
the preferred embodiment of the invention is provided with flow
distribution devices, such as vanes, perforated plates, and
1036781
honeycomb sections. These devices reduce turbulence and
eddies and diffuse and straighten the flow of air. Typically
the air is forced through a honeycomb cell structure having a
uniform cross-section. The most effective cell size is depend-
ent upon the velocity of the air used but in a cell with a
diagonal of 3~16 of an inch and a depth of some 4 inches the
wall material is relatively thin. About 0.010 has been found
most e~f`ective. In some instances a depth of theh~neycomb
section of more than 4 inches has been found useful but should
not be more than 6 inches. The air passage will normally be
the same width as the venturi section into which the fibers are
pro~ected and several times greater in the other cross-sectional
dimension. Thus the air inlet velocity in the larger air
passage in which the air straighteners and diffusers are located
is much less than the smaller duct at the venturi which provides
a uniform velocity across the width and depth of the inlet duct
and allows an acceleration of the air, eliminating turbulence,
The velocity variation across the width of the duct at
the point where the air flow advances into the venturi section
and projected fiber stream should be less than +10% and prefer-
ably less than ~5%. The average turbulence intensity or the
standard deviation of the velocity variation at this point is
less than 17% and preferably less than 8%. These values refer
to the portion of the air stream immediately Prior to the ven-
turi section and at a point where the fibrous flow mixes ~ith
the input air flow. It has been found that if the turbulence
intensities are large ? large eddies or vortices are present in
this region and the velocity profile is unstable and this pro-
duces an inlet flow which causes the fibrousparticles to dis-
perse in the expansion chamber and cause fluctuations and pul-
sations of the fiber and air flow mixture to give excessive
blotchiness in the web structure, The air passing through the
duct and at the venturi section should be adjusted to level the
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10367~1
the flow and reduce the turbulence and velocity distribution.
This is carried out by the adjustment of the saber tube.
It has been found that web streaks or blotchiness is due
to the air stream non-uniformity~ its profile and vortices
created at the boundary layers along the walls of the expansion
chamber.
It can be shown that there exists a layer of air ad~acent
to the wall surface through which a variation of velocity
between the fiber/air mixture and the surface is transmitted.
The whole of the frictional resistance betweenthe fibrous flow
and the surface occurs in this layer. The boundary layer con-
sists of a number of thin parallel stream bands each having a
slightly higher velocity than its inner neighbor. The stream
immediately adjacent to the surface of the wall is found to ad-
here to that surface at zero velocity. Working outwards from
the surface the next stream band has an extremely small velocity;
and each successive layer or band will have a slightly higher
velocity than its inner neighbor until the stream is reached
which has approximately full velocity of the fibrous mixture at
the center of the chamber. This last stream band is the outside
limit of the boundary layer and no fiber resistance is trans-
mitted to the wall surface of the chamber beyond this outer limit
provided vortices do not cause the fibers to be drawn into the
turbulent flow and thus causing clumps of fibers to be created
in these vortices.
The thickness of the boundary layer is important and may be
calculated from the formula:
d = 5.83 ( ~ ) 1/2 ~
where d = boundary layer thickness
R = Reynolds Number
1 = linear length of the walls surface
x = Linear distance at which "d" is to
be calculated.
~036781
The flow within the boundary may be laminar or turbulent
according to the particular point from the entrance to the expan-
sion chamber. Under some forms of flow within the apparatus the
boundary layer leaves the surface and curls up into a vortex or
whirlpool which is termed a separation and causes bunches of
fibers to form momentarily and be swept into the web structure
being formed on the condenser screen.
The thickness of the boundary layer increases with its
distance from the entrance to the expansion chamber in propor-
tion to the square root of the distance along the wall surfaceand also the Reynolds number of the flow.
The-boundary layer is always in evidence when the fibrous
flow is within the chamber and at relatively low velocities.
Hence at low fiber throughputs there is no separation; but as
the amount of fibers is increased, velocity separation commences
at a certain point and continues until a break away of the
boundary layer is caused thus forming pronounced vortices.
Within the expansion chamber it has been found that at the
entrance or at a point of the start of the expansion just below
the venturi, tbe flow is laminar for a short distance. This is
followed by a short length in which the flow changes from laminar
to turbulent, and it is here that the flow is unstable. The
length of the transition period of the layer is found to be
about the same length as the laminar flow portion. After this
section the boundary layer becomes very turbulent until a vortex
is formed.
In this turbulent layer the transmission of momentum is
made by the fibrous particles of higher velocity moving inwards
and giving up their momentum by collisions and that the break
away point occurs where the energy of the resistance at this
section of flow cannot be absorbed fast enough by the boundary
layer. Then the energy will be dissipated in the vortices so
formed. This is liable to occur with short length fibers such
10367~i
as wood and the finer denier textile materials.
Another problem caused with the boundary layer flow is
the variation of pressure within the layer. At the break away
point or formation of the vortex, a flow may occur opposite in
direction to the main fibrous flow so that within this reserved
air current along the chamber walls surface a positive pressure
may be created pulling fibrous particles into its path, thus
adding to the causes of the vortex itself. It is possible to
control this separation point by creating a high velocity air
stream so it passes thrcugh the boundary layer as generally
described in Canadian Patent 930,518.
The transition also depends on the roughness of the walls.
If the roughness is small the resulting disturbances will lie
below the threshold of the separation point and will have no
effect. However, when the roughness is large, the transition
will occur as they are presented to the flow.
The use of the venturi section and the large air input
chamber reduce the formation of random eddies. The invention
overcomes formation of eddies to provide for a uniform air
velocity profile across the width of the expansion chamber and
the venturi section where the fibers are projected into the air
stream.
In normal ~erodynamic web forming equipment the web is
constructed of a succession of extremely thin overlapping areas,
each area having a random arrangement of the fibrous materials.
These overlapping areas are normally referred to as shingle
planes. The lengthof these shingle planes is directly propor-
tional to the length of the forming chamber area and to the
thickness of the fibrous construction. Due to the use of an
angled air stream and inclined condenser screen it has been
found that the quality of the fibrous arrangement deteriorates
as the production speed is increased. The subject invention
makes use of a concentrated high velocity stream of fibers and
~1
~036781
air which is normally about 3 cms in thickness as it approaches
the condensing surfacej and the fibrous materials are deposited
in a succession of very small overlapping shingle planes on a
horizontal screen. The spread of the fibrous formation within
these planes may be accomplished by use of the variation of the
air flow into the expansion chamber via the combined use of
air stream diversion devices such as a saber tube and in the
preferred embodiment of the invention, inlet slots at the air
supply chamber and at the lickerin doffing bar area of the
duct wall.
The use of various sizes of openings in the air flow
distribution devices within the inlet duct also affect the
structure of the fibrous web structure upon the condenser
screen.
Another feature of the preferred embodiment of the inven-
tion is the provision of an inlet flow distribution device with-
in the walls of the inlet chamber and also just below the doff-
ing bar. These consist of a perforated plate fixed to an open-
ing in the wall and covered with an adjustable solid cover so
that the open area of the inlet may be changed to suit the
fibrous web construction on the condenser screen, by allowing
atmospheric air to enter the machine. The perforated plate
would normally have an open area of above 42% and have a
staggered hole arrangement.
Referring now to the drawings by numerals of reference,
and first to Fig. 1, 20 denotes the feed section, and 21 the
webbing section of a machine built according to one embodiment
of this invention.
The feed section comprises a hopper 25 into which fibrous
material may be fed from a conventional opener through a duct 26.
A port 27 extends across the top of the hopper at one side
thereof to permit escape to atmosphere of air that has been
entrapped in the fibrous material.
1~
S036781
The ~ibrous material flows from the hopper through opening
29 into a bin 30. The fibrous material is fed from this bin to
the web-forming section of the machine. The feed mechanism
shown is similar to that disclosed in the Canadian Patent No.
567,713.
This feed mechanism includes an endless floor apron or
conveyor belt 32 which is mounted in the base of the bin and on
which are secured a plurality of preferably wooden slats 34.
The apron 32 is mounted to travel over pulleys 36 and 38 which
are secured to shafts 40 and 42, respectively, that are ~ournal-
ed in the sides of the bin..
This apron carries the stock material from adjacent open-
ing 29 to an endless elevating apron or conveyor 45 which is
mounted to travel over pulleys 46 and 47, that are secured to
shafts 48 and 49, respectively, also ~ournaled in opposite
sides of the bin 30. The elevating apron is provided with a
plurality of straps 50 in which are embedded pins 52. The belt
is inclined upwardly; and the pins 52 are inclined to the
direction of travel of the belt. The pins 52 pick up tufts of
the stock material from the floor apron 32; and they carry
these tufts upwardly toward the top of the bin as the belt 45
travels upwardly.
Mounted in the upper portion of the bin to cooperate with
the elevating apron 45 in an endless stripping apron 55. This
apron is an endless belt which travels over pulleys 56 and 57
that are secured to the shafts 58 and 59, respectively, which
are also journaled in the sides of the bin. The apron 55
carries a plurality of straps 60 in which are embedded pins 62,
that are inclined to the direction of travel of the stripping
30 apron.
The roller 57, that drives the stripper apron, may be
driven from a motor 61 mounted on top of the feeder unit,
through a pulley 63 on the armature shaft of the motor, the belt
13
1036781
64, and the pulley 66, which is mounted on the same shaft with
the roller 57.
The purpose of the stripping apron 55 is to break up and
reduce the tufts of material, which are carried upwardly by the
pins 52 of the elevating apron, and to remove excess material
from the elevating apron, and move the excess material to the
loading end of the bin. The stripping apron removes excessive
fiber ~rom the pins 52 of the elevating apron, leaving only
small bunches or tufts on the individual pins 52.
The tufts remaining on the pins 52 of the elevating apron
are stripped from these pins by suction. A suction fan (not
shown) of conventional construction mounted in a housing 65
(Figs. 1 and 2) sucks the tufts of fibers off of the pins 52
through a duct 67 formed between the cover plate 68 of the bin
and the top of the elevating apron 45 and between the walls 70
and 71 of the fiber chute 73.
The suction fan draws the fibers through the chute and onto
the rotating foraminate feeder condenser 75, which may be of
conventional construction, and which rotates on a shaft 72
journaled in the screen box 74. Adjacent to condenser 75 and
positioned to cooperate therewith in forming a feed mat are
rollers 78, 79 and 80 (Fig. 2). The air is drawn over the pins
52 through duct 67 and chute 73 so that the fibers are compacted
between the rotary condenser 75 and the wall 71 of the chute.
The condenser is open at both ends and its opposite ends
are connected by ducts 82, 84 (Fig. 3), respectively, to a
manifold or plenum chamber 86, which is open at its upper end
end and which is connected by the short duct 88 with the housing
65 and the suction fan that is contained within the housing. The
30 fan exhausts through the opening 90 at one end of the housing
to atmosphere. The fan is driven from a motor (not shown)
through a pulley 92 (Fig. 1) which is secured to a shaft 94,
which drives a worm (not shown), or other suitable gearing
1~
1036781
connected with the fan.
The feed section of the machine is supported on rollers
124 (Fig. 1) which roll on guide rails 126 secured on the cover
plate 128 of the base of the machine.
The velocity of movement of the air through the fiber
chute is controlled by adjustable damper blades 95 (Fig. 2) that
are pivotally mounted in the plenum chamber, and that are
ad~ustable by manipulation of lever 96 which is pivotally
mounted at 91 on a bracket 93 that is secured to the screen box
1~ 74. Lever 96 is pivotally connected at 97 to one end of an
operating rod 98 that is pivotally connected at 99 to a bar 100
that, in turn, is pivotally connected by arms 101 to the hinge
pins 102 on which the damper blades 95 are mounted.
The mat of fibers is doffed from the feeder condenser 75
by the doffing roll 80, and delivered into the nip between a
conventional feed roll 110 and a conventional feed plate 112,
conventionally mounted. The feed roll feeds the mat of fibers
over the nose of the feed plate to a lickerin 114 (Fig. 4),
which is of conventional construction, and which rotates at
high speed and combs fibers from the mat.
The fibers are carried from the chute 73 (Fig. 1) to the
feed plate 112 by an air bridge produced by the suction of a
webber fan 120 (Fig. 5), which is mounted in a housing 121 in
the base of the machine beneath the feeder mechanism. The
webber fan 120 is driven by a motor 130 (Fig. 1), that is
mounted in the base of the machine, through pulley 132, belt 134,
and pulley 136. The pulley 136 is secured to the drive shaft
138 of the fan.
The fan 120 produces an air stream that moves tangentially
past the lickerin 114 so that the fibers combed by the lickerin
from the feed mat are doffed from the lickerin by centrifugal
force and the air stream, and are carried into the duct 140
(Fig. 4) that delivers them onto the horizontal foraminate
1036781
condenser belt 142 (Fig. 1). Duct 140 is bounded by walls 141
and 143.
The air is sucked through condenser belt 142 by the fan
120 and is returned by the recirculation duct 161 (Fig. 5) to
the fan inlet opening at 144 (Fig. 5). The air is exhausted
from the fan 120 at the outlet opening 146 and passes through a
duct 147 and a duct 149 into housing 150 (Fig. 1), where it
passes over a saber 152 (Figs. 1 and 4) and tangentially down-
wardly past the teeth of the lickerin, being recirculated
~hrough duct 161, thereby to doff further fibers from the
rotating lickerin. The saber, which is a roller journaled
eccentrically in the sides of the condenser fan unit, serves to
aid in doffing the fibers from the lickerin. The eccentric
mounting of the saber allows of varying the space between the
lickerin and the saber.
The condenser 142 (Fig. 1) is driven by a motor 153
through a pulley or sprocket 155, a belt or chain 157, and a
pulley or sprocket 159. The pulley or sprocket 155 is mounted
on the armature shaft of the motor 153; and the pulley or
sprocket 159 is mounted on a shaft on which a roller or sprocket
151 is secured. Condenser 142 travels over this roller or
sprocket and over a parallel roller or ~sprocket 148.
The lower section 145 (Fig. 4) of the wall 143 of the
duct 140 is adjustable to control the width of the discharge end
of this duct. This lower section 145 is pivoted at 166 on the
feeder frame, and is adjusted by an arm 163 which is pivotally
connected to this lower section at 165, and which is adjustable
by a screw 167 which threads into the lower portion of the
lickerin frame.
It is to be noted that the axes of the feeder condenser 75
and of the lickerin 114 lie in the same vertical plane and that
this plane is perpendicular to the upper reach of the webber
condenser 142 so that the flow of the fibers from the feeder
lB
~036781
condenser to the lickerin and thence to the webber condenser
is with gravity, and that the web formation is at right angles
to the vertical feed system.
The disposition of the feeder on top of the base of the
webber, and the vertical arrangement of the feeder condenser
and the lickerln combine to require a minimum space for the
combined feeder-webber. Moreover, this compact arrangement of
the feeder and webber minimizes the cost of the combined
machinery .
The feeder table 160, on which the motor 130 and webber
fan housing 121 are mounted, and the webber table 162 above
which the lower reach of the webber condenser belt 142 travels,
are supported between the legs 122 on which the plates 128 and
129 that support the feeder and the upper portion of the webber
are mounted. The legs are carried on adjustable feet 164 which
permit leveling the machine.
The web laid down on the upper reach of the condenser
belt 142 may be carried from the webber section of the machine
by this belt and delivered between the rotating knives 170 of a
conventional slitter 174. This machine forms no part of the
present invention.
The slitting knives are driven from a motor 176, that
drives knives 170 through a pulley 177, a belt 178 and a
pulley on shaft 179. The web travels between knives 170 and a
roller 171. This roller is adjustable toward and from the knives
by mechanism denoted generally at 172 forming no part of the
present invention. The web travels over rollers 181 and 182.
On the shaft 179 there is a pulley which drives a pulley on the
shaft that carries roller 182. A gear, which is mounted on
shaft 179 meshes with a gear on the shaft of roller 181; and
this shaft drives a fan 184 through pulleys 186 and 187 and
belt 185. Fan 184 supplies air through duct 188 to hopper 25
through the port 189 in the hopper. This air prevents the
17
10367Bl
fibrous material in the hopper from matting.
Mounted on top of the feeder may be an anti-static system
190, which may comprise a storage tank, a pipe 192 for drawing
water out of the tank, and a spray unit 194 for delivering a
spray into the feeder to humidify this unit to an extent to
offset static. A valve 196 may be provided to control the spray.
In the machine of Figs. 6 to 9 inclusive, the flbers are
delivered by a conventional pneumatic delivery system from a
conventional opener, for instance, into a chute 200 in which
is mounted a level control lever 202 and from which the fibers
are fed by the two oppositely rotating chute feed rolls 204
and 206 onto an endless floor apron or conveyor belt 208 similar
to the belt 32 of the first described embodiment of the inven-
tion, and on which are secured a plurality of preferably wooden
slots 210. These slots are provided with pins 212 which pick
up the tufts of fibers delivered into the bin 214 by the chute
200. The apron 208 is mounted to travel over pulleys 216 and
218 which are secured to shaft 220 and 222, respectively, that
are ~ournaled in the sides of the bin.
This apron carries the stock material from beneath the
chute 200 to an endless elevating apron or conveyor 224, which
is mounted to travel over pulleys 226 and 228 that are secured
to shafts 230 and 232, respectively, also journaled in the
sides of the bin 214. The elevating apron is provided with a
plurality of spaced straps 234 in which are embedded pins 236.
These pins pick up tufts of fibers from the floor apron 208;
and they carry these tufts upwardly toward the top of the bin
214 as the belt 224 travels upwardly.
A container 238 is disposed adjacent the right-hand end
of the conveyor 208 to catch dirt and trash picked up by this
conveyor and a stripper 240 is disposed just above this end
of this conveyor to aid in removing trash from this conveyor
and deflecting it into the container 238. A clean-out door
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(not shown) may be provided at one end of this container
through which the collected dirt and trash can be removed from
the container.
Mounted in the upper portion of the bin to cooperate with
the elevating apron 224 is an endless stripping apron 242. This
apron travels over pulleys 244 and 246 that are secured to shafts
248 and 250, respectively, which are also journaled in the sides
of bin 214. The apron 242 carries a plurality of straps 252
in which are embedded pins 254. The stripping apron breaks up
1~ and reduces the tufts of material, which are carried upwardly
b~ the pins 236 of the elevating apron, and removes excess
material from the elevating apron, delivering the excess back
into the bin.
The plate 256 pivoted at 258 on the sides of the bin
keeps the fibers delivered into the bin in contact with the apron
208.
The tufts remaining on the pins 236 of the elevating apron
are stripped from these pins by suction. A suction fan (not
shown) of conventional construction mounted in a housing 260
and driven by a motor 262 sucks the tufts of fibers off of pins
236 into a duct 264. Air is admitted to the duct through open-
ing 266 in the sides of an inverted drum-like protrusion 268
on the top of bin 214. Apertures 270 in an extension of this
top wall also admit air to duct 264. The amount of air
admissible through the apertures 270 is controlled by a slide
272 which may be adjusted to clear or close one or more of
these apertures.
The tufts of ~ibers carried by the air stream flowing
through duct 264 are carried through the trumpet 274 around a
rotary feeder condenser 276. The trumpet is bounded on one
side by a knee 280, that projects down into bin 282~ and on
the opposed side by an endless screen 278 that travels around
the foraminate periphery 284 of the condenser and over the
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drive roller 286. Roller 286 is journaled on a shaft 288
mounted in opposed sides of bin 282. Air is sucked into the
condenser through the opening 290 in its perimeter, causing
fibers to be drawn out of the air stream in the trumpet section
274 and to be deposited as a mat on the condenser.
The air is sucked through the duct 292 which extends
axially through the condenser out both ends thereof into ducts
294 which empty into a vacuum expansion chamber 296 from whence
the air is sucked by the fan in housing 2~0. The open or ex-
haust end 296 of housing 260 is connected to a dust collection
system.
A doffing bar 298 doffs the mat from the condenser; anda ~eed roll 300 feeds the mat over the nose bar 302 of knee 280
to the rotating lickerin 303. Feed roll 300 is journaled on
shaft 304; and the lickerin is rotatably mounted by shaft 306.
The lickerin may be driven by a motor 314 through a con-
ventional pulley or a sprocket and chain drive, the drive
member of which is shown at 316 and the driven member at 317
in Fig. 7. The motor is mounted by a bracket 318 on the base
of the machine.
The lickerin in its rotation combs with its teeth 305
(Fig. 8) the fibers from the mat fed to it over the nose bar;
and those fibers are doffed from the lickerin by centrifugal
force and by an air stream flowing through the venturi section
308 of a duct 310 which is bounded on one side, above the licker-
in, by the knee 280 and on the opposite side by the wall 312 of
the bin 282. A cover 323 encloses the major portion of the
periphery of the lickerin. An eccentrically-mounted, rotatably
ad~ustable saber tube 320 mounted in the wall section 322 of
bin 282 opposite the lickerin adjustably controls the width of
the venturi section 308 of duct 310.
The fibers doffed from the lickerin are carried by the air
stream flowing past the lickerin into a duct or condensing
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chamber 324 of gradually expanding width, and deposited on an
endless screen conveyor 326 that travels over rollers 328 and
330 mounted on rotatable shafts 332 and 334, respectively.
Air is sucked through the foraminate conveyor 326 by a
fan 336 which is driven by a motor 338. The air ~s sucked into
a vacuum box 340, mounted in the base o~ the machine between
the upper and lower reaches o~ conveyor 326, through a perforate
dif~user ~42 into a box 344, and thence thro~gh twin conduits
346 which,c~mmunicate with box 344 at opposite sides thereof.
The ducts. 346 communicate with a vacuum expansion chamber 348
from which the air is sucked by fan 336 and delivered through
duct 350 and an air distribution tube 352 into a distribution
chamber 354.
The tube 352 has a longitudinally-extending slot in it
through which the air flows into chamber 354. A vertically
adjustable blade 358 that is mounted to slide in the top wall
360 of chamber 354 controls the air of flow from tube 352.
When this blade is extended into the slot 356 in tube 352 it
splits the air flowing from the tube into two streams and causes
this air to swirl about in chamber 354. A nose piece 362 se-
cured to the bottom of the tube further divides the air stream
and directs it into a screen 364, which extends àcross chamber
354 near the bottom thereof. A handle 366 is secured to blade
358 to effect its adjustment.
The air is sucked from the chamber 354, in a closed re-
circulating circuit back to fan 336. The fan drives the air
through the screen 364 and a perforate diffuser 368 extending
over the bottom of the chamber into the velocity improvement
chamber 310. This chamber is bounded by the curved, downwardly
converging wall 312 and the opposed curved wall 370 of knee 280.
An ad~ustable atmospheric air inlet is provided in wall
312 ~ust above saber 320 to control the rate of air flow
through the venturi section 308 of the duct 310. This inlet
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comprises the apertures 372 in the wall and the manually ad~ust-
able slide 374 which is adjustable on the outside of the wall
to open or close the apertures 372 through which atmospheric air
can flow into the duct.
A further adjustable atmospheric air inlet to duct 310 is
provided below the lickerin 302~ This also comprises aperture
376 in the lower wall 378 of duct 310, which bounds at one side
condensing chamber 324. A slide 380 in the outside of this wall
enables the amount of atmospheric air admitted through apertures
ln 376 to be controlled.
Wall 378 may be stationary but opposed wall 322 of the
condensing chamber 3Z4 is pivotally mounted around saber 320
for angular adjustment toward and from wall 378. This ad~ustment
allows control of the width of the condensing chamber and of the
divergence downwardly of these walls in one direction. The other
two walls 382 and 384 of this chamber also diverge from one
another downwardly to product condenser 326. A roller 386
carried on the bottom of wall 322 controls the thickness or
~eight of the web W formed on the product condenser. A coil
20 spring 388 keeps this roller pressed against the web.
A doffing bar 390 is secured to the wall 378 to aid in
doffing fibers from the lickerin 303. As an example of what
the apparatus illustrated in Figs. 6, 7 and 8 can do, a 45
inch wide nonwoven web structure was formed. For this purpose,
the fibrous material used was 1-1/2 denier l-g/16 inch long
staple polyester fiber, opened via Curlator Corporation's
R~ND0-opening equipment and pneumatically fed into the rear of
the feeder. The feeder constructed a feed mat of 14 ounces per
square yard which was fed to the lickerin 303 via the feed roll
300 and nose bar 302. A 12 inch diameter lickerin"having a
metallic covering of 40 teeth per square inch was used, each
tooth having a pro~ected height above the lickerin surface of
0.156 inches and 0.025 inch thick with a forward rake of 40.
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103~78~ .
The clearance between lickerin teeth and the nose bar working
point was maintained at .007 inch while the distance between the
lickerin and the nose bar tail was set at 0.015 inches. The
lickerin rotated at 6000 RPM and projected a uniform stream of
fibers into the venturi area 308 at an initial uniform velocity
of 18,600 feet per minute. The average air velocity at the
inlet of the venturi section ~ust prior to the mixing zone of
input air and fiber was 14,500 feet per minute and increased
~nto the venturi to 22,300 feet per minute with a turbulence
intensi~y of 0.5~ The velocity profile across the cross-
sectional area of the venturi had a gradient of less than 1%
per 30 CM of width excluding the wall attachment effects at the
outer extremities of this area.
Since the inlet velocity into the expansion chamber was
subsonic the velocity through the chamber decreased as the
distance increased; however the temperature increased. The air
pressure remained almost constant throughout the chamber to the
condensing area. The dimension of the input duct just prior to
the fibrous projection point was 2 inches in depth~ the minimum
depth below the point of maximum projection of the lickerin
into the venturi was 1-5/16 inches, the distance between the
walls at the entrance of the expansion chamber just below the
doffing blade was 1-11/16 inches and at the point just above
the condenser screen the width between the walls or covers was
2-9/ 16 inches; the final velocity here was 11,300 feet per
minute.
The following production rates were obtained at a web
weight of 1-1/2 ounces per square yard:
FEET PER MINUTEPOUNDS PER HOUR PER INCH
125 6.5
150 7.8
175 9.1
200 10.4
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In the machine of Figs. 6, 7 and 8, the feed mat of
fibrous materials conveyed to the web forming unit by the
feeder should not exceed 14 ozs. per square yard for the Example
given. The inlet air to the WEBBER is provided by a fan 336
through a duct system 350 which e~ects a uniform flow of air
from a centrally located tube 352 and adjustable slot means
356, 358 at the inlet chamber 354 so that air expands from the
supply tube to both sides of the chamber~ The distribution
screens 364, 368 provide a uniform flow substantially free
from turbulence and vortices. The fibrous flow is in a vertical
aspect. The web formation is in a horizontal aspect. The doff-
ing bar 39jO should be set between .007" and .010" from the teeth
of the lickerin 303. The vertical center line of the machine is
the tangent line to the outer edge of the lickerin and at right
angles to the condenser 326. The outer edge of the nose bar
tail 302 is set away from the center line and above the lickerin
by a distance of not more than 17 mm.
Previous aerodynamic web forming equipment with a fibrous
stream at an angle to the horizontal, such as the RAND0-WEBBER,
usually have between 12 and 25 downward flow from the hori-
zontal from the lickerin to the condenser, have a lickerin
cylinder which protrudes excessively into the air flow stream
over the saber and hence cause unstable and non-uniform
regions of air flow which are advanced to the condenser and
cause unstable eddies upstream from the condenser surface and
also cause unstable back pressure flow across the venturi
section. It is important that the lickerin only protrude into
the air stream by an amount necessary to strip the boundary
layer surrounding the cylinder's surface; and this is normally
between 1/16 and 1/2 of an inch projection.
While the invention has been described in connection with
specific embodiments thereof, it will be understood that it is
capable of further modification, and this application is
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intended to cover any modifications or adaptions of the inven-
tion which come within its scope or the limits o~ the appended
claims.
2~
