CA1279829C - Apparatus for collecting and discharging waste material - Google Patents

Abstract

ABSTRACT
"Apparatus for Collecting and Discharging Waste Material"

The apparatus disclosed comprises peripheral rows 1 and 2 of teeth T arranged on rotatable cylindrical shafts 3 and 4. The teeth T on each shaft 3 and 4 intercalate so that an entrapment zone Z for waste material is formed thereat during contra-wise rotation of the shafts 3 and 4. The teeth T in each row pass through respective slits S formed between the blade edge 12' of rectilinear scraper blades 12 placed between the rows and resting on the shafts. The scraper blades 12 remove waste material from and between the teeth T for discharge from the machine. To prevent the waste material being caught by the cutting action between the leading faces of the teeth T passing the scraper blades edges 12' the magnitude of the angle A formed at any time between those leading faces and the blades edges 12' as the teeth T pass through slits S, has a value determined by the shape of the leading faces of the teeth and blade edges 12' of the scraper blades so that the inducement of frictional engagement in relation to the materials being handled is never sufficient for a biting or cutting action to ensue.

Description

1L~ 3~'~9 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.

~,~7~ 3 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, .~, , .

~ 9 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 'X

~ ~ ~ 9 ~3 - 3a -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 _4_ ~ '3~ 3 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:

~1 ~ ~ .

-5~ 9 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.
.~

98~'3 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.

-7~ g ~ ~ g 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 ~;`
, ~798'~

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.

t,~

~'~798~

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 X '`' 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.

.

~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.

r .i ~

Claims (10)

1. 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 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.

2. Apparatus as claimed in claim 1 wherein each said support means is spaced one from the other by a cylindrical separator mounted for rotation with said at least one rotatable shaft, said material-clearing elements being in the form of flat blades having upper and lower rectilinear surfaces with a lower surface portion thereof lying tangentially on a respective one of said separators, said angular relationship defining means being constituted by the leading face of each of said teeth having a predetermined curvature to provide said angle of required magnitude formed between a said edge of a said leading tooth face and a respective upper rectilinear blade edge of said material-clearing elements.

3. Apparatus as claimed in claim 2 wherein said predetermined curvature lies on the involute of a base circle being the generatrix of said cylindrical separators, such that said angle of required magnitude is 90°.

4. Apparatus as claimed in claim 2 wherein said predetermined curvature is substantially the arc of a circle.

5. Apparatus as claimed in claim 3 wherein the trailing face of each of said teeth is the same as that of said leading face thereof but of opposite hand, whereby to permit the material collected to be disgorged upon reversal of rotation of the or each shaft.

6. Apparatus as claimed in claim 5 wherein said flat blades are portions of a stationary metal band arranged around said cylindrical separators.

7. Apparatus as claimed in claim 6 wherein there are two said rotatable shafts, said two shafts being arranged such that the teeth on respective ones of said support means on one shaft intercalates with the teeth on respective ones of said support means on the other shaft to form thereat an entrapment zone for waste material as said two shafts are rotated in contra-wise directions.

8. Apparatus as claimed in claim 4 wherein the trailing face of each of said teeth is the same as that of said leading face thereof but of opposite hand, whereby to permit the material collected to be disgorged upon reversal of rotation of the or each shaft.

9. Apparatus as claimed in claim 8 wherein said flat blades are portions of a stationary metal band arranged around said cylindrical separators.

10. Apparatus as claimed in claim 9 wherein there are two said rotatable shafts, said two shafts being arranged such that the teeth on respective ones of said support means on one shaft intercalates with the teeth on respective ones of said support means on the other shaft to form thereat an entrapment zone for waste material as said two shafts are rotated in contra-wise directions.