Note: Descriptions are shown in the official language in which they were submitted.
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Apparfltusfor Collecting and Discharging Waste Material.
FIELD OF TlIE INVENTION
The invention relates to apparatus for collecting and discharging
agglomerations of miscellaneous ma-tter for example as is to be found in the
form of municipal rubbish and floating detritus on a water surface.
Su~ch matter may include cans and bo-ttles, articles of wood or cardboard
or plastics material, ropes and cordage, weeds, textile waste, rotting
substances such as household refuse and dead fish and birds and, also
viscous liquids such as bunker oils and tars.
~ACKGROUND OF THE INVENTION
Apparatus for collecting and discharging waste material is
known utilising two cooperating sets of moving toothed structures,
each being provided wi-th plate-like teeth lying in parallel planes
parallel to the direc-tion of motion, and spaced, on each structure,
at intervals perpendicular to those planes. The teeth of both
s-tructures are mutually intercalated in a collection zone where they
are both moving in the same direction and, at posi-tions remote from
the collection zone, bo-th structures interact with stationary combs
comprising se-ts of blades which lie between adjacen-t lines of -teeth,
closely fitting against the sides of the teeth and their separating
means to remove matter trapped between the -teeth or adhering to the
sides thereof. Means are also provided whereby the toothed structures,
together with their comb assemblies, may become separated to permi-t
the passage of matter which is too tough or bulky to be shredded by
the teeth.
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Both toothed structures may take -the form of rotatably mounted
shafts carrying assemblies of -thin metal discs with circumf`erentialLy
formed teeth, the discs being separated by relatively thick plain
discs of diameter somewha-t less than that at the tooth roots, all
members being clamped together so -that -the assembly rotates as an
integral unit.
Alternatively, one of the structures may be a shaft assembly
as described and the other a belt type conveyor bearing lines of
teeth at intervals across its width.
Although teeth of almost any conceivable shape may be used -to
create an entrapment and collecting action~ difficulties arise with
the prior ar-tapparatusas the spoil enters the separating scraper zone
because of the generation of a biting action on -the material developed
between the disc teeth and separator combs as the teeth move relative
to the combs. If the parts are not sufficiently robust or the driving
force is inadequate, this biting action will defeat the objective of
the separa-tor combs and resul-t in either the machine breaking or
jamming even when dealing with soft materials such as cordage or plastic
bags.
SUMMARY OF THE INVENTION
It is one object of the invention -to provideapparatus of` the
above type although not necessarily incorporating the two intercala-ted
sets of toothed structures, wherein the cooperating teeth of the discs
and separator combs are designed such that the possibility of matter
becoming trapped and jamming the machine by the cu-tting action
between the tee-th and combs, if the matter is too robust to be sheared,
as would be the case with, for instance, wire or thick metal objects,
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is obviated~ The necessity, as in the prior art, for providing
a machine which is very powerful ancl furnished with hardened
and ground teeth and combs is thereby eliminated.
An aspect of the invention is as follows:
Apparatus for collecting and discharging waste
material comprising:
at least one rotatable shaft;
a plurality of support means mounted in spaced
relationship for rotation with said at least one shaft, each
said support means being provided with a plurality of teeth,
each tooth of said teeth having side flanks delimiting a
leading tooth face or edge which is presented to the material
to be collected by said teeth as said at least one shaft
rotates;
a plurality of material-clearing elements each one
of which being respectively mounted between said support
means, said elements having material-cleaning blade edges
defining a series of slits respectively between which said
teeth on a said support means passes with said side flanks
in closely spaced adjacent relationship to said blade edges
such that material collected between each said support means
is removed for passage to a discharge zone; and
means defining an angular relationship between
said elements and said teeth such that the angle formed at
any time between the edges of said leading tooth face of
each advancing tooth and an adjacent blade edge of a respective
one of said slits through which said teeth on each said
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support means passes is of a magnitude necessary to ensure
that said teeth and said elements do not cooperatively act
to bite or cut into the waste material of whatever character
or quality of such an extent as to prevent said waste material
passing smoothly to said discharge zone.
With this arrangement the biting action set up
between the slits and the rotating teeth, is never sufficient
to induce the required amount of frictional engagement in
relation to the material being handled by the machine, so
that the waste material being collected does not therefore,
become caught between the teeth and the material-gathering
elements but is passed
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smoothly by these elements -to the d:ischarge zone.
In a preferred form cylindrical separators are be-tween the
peripheral rows of teeth of the material-gathering elements in the
form of flat scraper blades having rectilinear blade edges, which
rest tangentially on the separators. The leading f'aces of the rotating
teeth are then configured to lie on the involute of a base circle
being the generatrix of the rotating cyclindrical separators. In
this ca,se the angle between the scraper blade edges and the edges of
the leading faces of the rotating teeth is always 90.
Other features and advantages of the invention will become clear
from the following detailed description of preferred embodiments of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
; The invention will be described by way of example with reference
to the accompanying drawings wherein:
Figure la is a front elevation of apparatù~ for collec-ting and
discharging waste material as seen from the direction from which
spoil is being accepted, provided with teeth bearing collector discs
and waste material removing scraper blades according to one form of
the invention:
Figure lb is a sec-tional view of the apparatus of Figure.la ta~en along
the line A-A:
Figure lc is a view of the machine of Figure la taken along the line
B-B of Figure lb:
Figure 2 illustrates one way of determining the curvature of the
leading face of -the teeth of the collector discs in-teracting with a
scr~per comb blade of rectilinear form.
Figure 3 shows a preferred construc-tion of a scraper comb:
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Figure 4 shows a further form of scraper comb, and
Figures 5a and 5b shows preferred arrangements for driving the machine
of Figure la.
BEST MODES OF PERFORMING THE INVENTION
The apparatus for collecting and discharging waste material shown
in the drawings, and more particularly in Figures la, lb and lc
comprises upper and lower rows 1 and 2 of peripheral teeth T arranged
respectively on hori~on-tal shafts 3 and 4.
The lower shaft 4 i9 journalled for rotation in f`ixed bearings
5 moun-ted at fixed positions 6, while the upper shaft 3 is mounted
on bearings at the free ends of lever arms 7 which swing about pivots
8 attached to a fixed position 9. Positions ô and 9 bear a fixed
relationship to one another, as for instance, would be the case when
the various parts are attached to a mounting framework.
The rows 1 and 2 of teeth T are set apart in planar fashion
by cylindrical spacers 10, and are mounted to have their respective
rows of teeth T at least partially intercalated to form an entrapment
zone Z for waste material as shown in Flgure lb, as the shaft 3 and 4
rotate in contra-wigefashion as lndicated by the arrows ll.
End portions of scraper comb plates 12 having rectilinear blade
edges 12', are mounted between the rows 1 and 2 and press firrnly
against the separa-tors 10, with their blade edges 12' in close fitting
relationship to the side flanks of -teeth T, the other ends being fixed
by any conveniellt known method to the lever arms 7 for those on the
upper shaft 3, and to the fixed location 6 for those on the lower
shaft ~. The blade edges 12' of ad~acent scraper blades 12 form slits S
between which the teeth T of each respective row pass as the shafts
3 and 4 rotate.
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Material thus entering the zone Z is crushed, impaled or
shredded depending on its nature. Viscous substances such QS tars
or heavy oils become convoluted around the -t;eeth T of the cliscs and
adhere strongly to the sides thereof. Objects which are too tough to
be dealt with as described cause the upper shaft 3 to rise and ride
over them, the teeth T then exerting a gripping func-tion to permi-t
this to happen.
After leaving the entrapmen-t zone Z the spoil is stripped from
the teeth T by -the action of the scraper comb blades 12 as the teeth
T pass through the slits S, for deposition in a collec-tion chamber
(not shown)f~r feeding -to any subsequent process.
Although not illustrated shafts 3 and 4 which need not neces-
sarily rotate a-t the same speed, may be driven from a power source
of any known type by a transmission system such as hydraulic motors
on the shaft ends connected by pipeline to a pump and motor unit.
Chain and linkwork systems may also be used.
The tee-th T of the discs in rows 1 and 2 are specially designed
in accordance with the invention, so that, as described earlier, the
biting action effected between the leading faces of the teeth T
presented to the material being collected as the shafts 3 and 4 rotate
and scraper comb blade edges 12'to cut and shear -the material being
gathered so causing clogging or breakdown, is eliminated.
This biting action will occur if -the "attack" angle with respect
to the m~terial being ga-thered, formed at any time between the leading
faces of teeth T and the edges 12' of the scraper comb blades 12 as
the teeth pass through the slits S between -them, is below a certain
value, taking into account the roughness and sharpness of the
interacting surfaces and -the nature of the waste material in question.
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The phenomenon is easi:Ly understood by considering -the effect
of scissor blades. If the blades are wide open to an angle of ~0
or greater, they will not bite into a piece of paper however sharp
they are.
However, as the "attack" angle between the blades gradually
decreases a biting and cutting ac-tion will ensue. It has been found
for example that with teeth and scraper comb blades that have smooth
~urfaces, the undesired biting action did not occur with angle of
attack ~ greatér than 70 .
The attack angle is of the required magnitude in the embodiment
of the invention illustrated when theleading face of each tooth T
lies on the involute 13 of the circle 14, whose
diameter i8 that of the cylindrical separators 10 as shown in Figure 2.
The heavily lined portion 15 of the involute curve 13 in
15 Figure 2, is the leading face of a representative tooth R, while
the dotted portion 16 is the trailing face of tooth R. The attack
angle at any time may be defined by the angle A formed between tangen-ts
on the curve 13 at the points of intersection of tangents to the circle
14 with -the curve 13, the latter tangents being extensione of the
scraper comb blades 12 (not shown in Figure 2) lying on the separators
lO,if it be imagined for purposes of illustration,that -the circle 14
rotates with respect to the curve 13.
Since the curve 13 is the involute of the circle 14, the angle
of attack A in Fi.gure 2, between the leading face of the -tooth R
and a fixed scraper blade, is always 90 as the tooth R rota-tes in
practice, in the direction of -the arrow 17 about the centre 18.
If either of -the shaf-ts 3 and 4 are always rotated in one
direc-tion the shape of the trailing flank 16 is not important, and may
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take the form of a straight line descending from the tooth cres-t
-to the root of -the ad~acent tooth.
However, it will sometimes be desirable to regurgitate or
disgorge the collected spoil by reversing the rotation of the shafts
3 and 4, an opposi~ely facing set of scraper blades at some other point
on the circumference being used to disgorge the spoil. In such a
case, the tooth flank 16 should then be the reverse of the original
shape leading flank 15 as shown.
The necessary shape of the flanks of teeth T having a constant,
but different attack angle, may be found with -the assistance of the
formula:
L = R x tanA x (e ~ /tanA - 1)
Where L = Length of tangent to generating circle.
6~ = Angular distance of tangent polnt from the star-t point of
the curve.
R = Radius of base circle
A = Attack angle.
Curve 19 shown in Figure 2, is calculated from this formula
with an attack angle 20 of 70 . This smaller attack angle is some-
times of advantage in that, for a given desired tooth height, the
tooth is narrower and more may be used around the circumfererlce. A
composite curve having an attack angle which varies with the tooth
height, but is nowhere less than the minimum requirement may also
sometimes be of value. It is, in practice, usually possible to
approximate the mathematically correct curve with a portion of a
plain circular arc, for which it is easier to arrange manufacture.
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Figure 3 shows a modified form of scraper comb blade in the form
of a continou~ metal band 21 which loosely engages the circumference
of the separators 10 and also a stationary reaction rod 22 wtlicl
spans -tlle entire machine longitudinally of the shafts 3 and 4.
To forrn the band 21, the ends of a metal strip may be welded
together or any known convenient type of end ~joint may be used at
some indifferent position, 8uch as, for instance, a bolt and nut
in rear of -the rod 22.
Figure 4 show3 a further modified form of scraper comb blade
in the form of a plastics material moulding 23 such as nylon is
provided witll an open-ended slot to engage the reaction rod 22 as
before. The moulding 23 is provided wi-th a circular opening 24
accommodating the separators 10 which are of smaller diameter owing
to the curvature of tlle sides of the type of scraper blade 23 the attack
angle A is increased and this will sometirnes be useful when it is
desirable to use disc teeth which would have a smaller attack angle
against a straight scraper blade.
Both the types shown in Figures 3 and 4 may be used for regur-
gitating types of machine in which disgorgement occurs on reversal
of rotatiolls of the shafta 3 and 4.
Figure 5 shows a method of driving the machine for collecting
and discharging waste material so as to obtain the necessary contra-
riwise rotation of -the upper and lower shafts 3 and 4 and the rise
aod fall motion of the upper assembly by means of a single chain
and which depends upon the convenient property of being able to engage
: sprockets at both sides of the cllain.
Dashed lines 25 are repre6entations of upper and lower tvothed
disc assemblie3 being dr:lven in the directions of arrows 26 to accept
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spoil arriving in the direction of` arrow 27, the shafts of the assemblies
being attached to chain sprockets 28.
In Figure 5a the sprockets 28 are shown as the same size as
is also a sprocket 29 which is in a fixed position and powered to rotate
S in the direc-tion shown. A single endless chain C i6 routed as shown by
the dashed line C so as to provide the rotations required. The lever arm
7 carry~ng the upper shaft disc assembly 3 is showrl in the extreme up alld
down positions which occur during rise and fall motion. Althougll strict
mathematical accuracy is not obtainable, it is possible to select a length
of lever arm 7 and the position of its pivot in relation -to the size and
extreme positions of the upper shaft sprocket so that the total length of
the chain C in the system remains constant from a practical point of view,
the need for a heavily biassed jockey sprocket -to take up slack being thereby
avoided.
In a case when the -two driven sprockets are to be of diff`ering
size to provide differing shaft speeds and/or when it is desirable to take
advantage of the ability of a chain-drive system to provide a speed reduc-
tion ratio relative to the driving sprocket it will not alw~ys be possible
to use the simple system of Figure 5a so that the oppositely moving parts
of the chain remain clear of each other. The difficulty may be overcome
by adopting tlle more complicated arrangement of Figure 5b. In thiæ diagram
the two main driven sprockets 28 are shown in difrerent sizes. Two small
sprockets 30 are s170wn in fixed positions, power being delivered to either
of them and -the other acting as an idler to permit the necessary chain
clearances to be obtained. The cl-ain is routed as shown, but in this case
the lever arm 7 must be pivoted forward of -the shaft assembly centres
instead of in rear. The advantage of sensibly lnvariant chain length may
be reallsed as b0fore.
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~l-though a preferred embodiment of the invention ha6 been
described with reference to a machine incorporating two sets of inter-
calating toothed structures, it i8 equally applicable to a machine
employing a single set, and this is reflected in the appended claims.
Moreover additions and modifications to the disclosed embodi-
men-ts will be apparent to one skilled in the art but such will be within
the scope of the claims which follow. For example to achieve the
results of the invention, it is no-t essential that the scraper comb
blades be rectilinear and the co-operating leading faces of the
rotatingteeth be curved, so long as the required angular relation-
ship between them is preserved.
Thus the leading faces of the tee-th (or faceedges -thereof) may
be rectilinear and the scraper blade edges curved, or alterna-tively
the leading faces (or face edges thereof) and blade edges may be of
curved profile as appropria-te.
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