CA1037448A

CA1037448A - Tire shredding machine

Info

Publication number: CA1037448A
Application number: CA212,465A
Authority: CA
Inventors: Charles L. Cunningham; Jimmie L. Holladay
Original assignee: Coats Co Inc
Current assignee: Coats Co Inc
Priority date: 1974-03-25
Filing date: 1974-10-28
Publication date: 1978-08-29
Also published as: GB1446408A; DE2455056A1; JPS50128884A; US3868062A; JPS5336913B2

Abstract

ABSTRACT OF THE DISCLOSURE
A shredding machine for tires or the like including a head having generally parralel, rotatable shafts each bearing feeding and cutting elements thereon for coaction with the feeding and cutting elements on the other shaft.
Bidirectional, hydraulic motors are operable to rotate the shafts in opposite directions and are included in a closed loop hydraulic circuit with a hydraulic pump. The circuits is also provided with a device for reversing the direction of fluid flow in the line to reverse the direction of the motors in response to an increase in pressure in the line in excess of a predetermined amount. The circuit also in-cludes a flow control valve for limiting volumetric flow of hydraulic fluid to one of the motors so that the same will, when in a no-load condition, rotate at a lesser rate than the other. The circuit also includes a bidirectional pres-sure relief valve.

Description

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TIRE SHREDDING M~CI1INE ' ~,r ', CKGROUND OF TH~ INVENrrION :`
This :lnv~ntion relates to shreddirlcJ mach:ines and, .~;
; more speciically, to shreddincJ machine~ desicJned to shred, .~
.. ;.' or disposal purposes, di~icult material, such as used tires. . .
;~"~
~, Published prior art known to the applicant includes .
Bowman U.S. Patent 2,368,102; Stanton U S. Patent 3,627,212~ :
Nelson U.S. Patent 3~,565,6~97; Schweiyert et al U.S~ Patent : -.
3,664,592; and Rossler U.S Patent 3,662,964.
10 ~ In present~day society,: waste disposal problems ~f F all~kinds are on~the upsarge. One particular facet of " .. . .
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:. the problem is posed by th.e increasing number of vehicles -.. -on the road. It .is the disposa-l of worn-out vehicle tires. ..
. ~
There have been a variety. of prior proposals for -`
tire cutting, shredding or subdividing apparatus, some of .. which are exemplified by the foregoing patents... In general, ; prior proposals have not.proved sati.sfactory or any one of . .
a variety of reasons, Frequentl.y, the apparatus is extremely :`. .
expensive and, therefore, out of the reach of th.e owner of a ..
relatively small tire servicing facility with. th.e result .th.at .
such an owner is forced to have whole tires removed rom his ,- ". :~;: .' . premises, i;~
.~ Where attempts have been made to overcome the fore- ~
going problem, other di~ficulties have resulted. Frequenkly, ~`
,, ,:
tire shredders de~igned for use by individual owners o~ tire . ,., . ; ~ . .
';.~ servicing acilities are underpowered due to the nature o ~:

t~ the shredding apparatus itself and a desire to adapt the same ... or hookup to a conventional source of electrical power .

., ~ without the need for speclal wiring. This has produced `., ~ apparatus having a special motor reversing circuit.
,:, .i~ 20 : Specifically, in one~such apparatus, an electrical : motor is mechanically coupled to. the shredding head and a :i .
current monitoring device monitors the flow of electrical ; current to the motor. When the current flow increases ~: beyond a predetermined point, indicative of an increased load on the motor due to jammed ti~e carcas.ses in the ;;
cutting head, a reversing circuit is energized to reverse `~
" l ~ ,,.
.: the motor for a short period of time to.expel the tire. This approach, while theoretically practical, has proved less than `.
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satisfactory in practice due to the expense o~ th.e circuits, .~ : .
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the possibility of reversing circuit failure resulting in ; ;
motor burn-out; and difficulties encountered in rapidly ~ -reversing relatively large motors. -SUMM~RY OF THE INVENTION
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It is the principal object of the invention to provide a new and improved shredding apparatus that is .. .. ...
especially adapted for use in tire shredding or cutting :;
:, . . ~. . . .
operations for disposal purposes. More specifically, it is an object of the invention to provide such an apparatus ;
i~ 10 which is economical in cost so as to enable iks use by `
individual owners of tire servicing facilities and which is ~
:';'... ::
not prone to damage due to electrical malfunction or diEficult-ies encountered in khe operation of large electrical motors~
~ he principal objeck is attained by the invention which contemplates a shredding machine that comprlses a cutting head including a pair of generally parallel, rotatable . . . . .`.
shafts each having cutting and feeding means thereon, a pair i of bidirectional, rotational output, hydraulic motors, one i for each shaft, for rotating the shafts in opposite directions, , ~, ., . . - : . - .
and a~hydrau1ic pump; means for drlving the pump. A conduit ~ ~:
means connects the pump~to~the motors in parallel, defining ~``~`','.!.'"
a closed loop,~and a~means associated with one of the pump~and;the conduit means is operable to reverse the direation of flow of hydraulic fluid in the conduit means and to thereby reverse the direction of rotation of the hydraulic motors. A pressure responsive means is associated ';
; with the conduit means for sensing when the pressure therein ~

exceeds a predetermined value for operating the reversing i means for a predetermined period Oe time.
A pressure sensing device is associated with the hydraulic circuit~and, when pressure in the same rises to j, , '": '' "'' : .,: " .
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~i exceed a predetermined value, the same is operative to cause .. reversal of the direction of flow of hydraulic fluid to .`
-. reverse the bidirectional hydraulic motors for a short period ``. .
~ of time sufficient to partially expel a tire.
1 ; :. . r~
. In a highly preferred embodiment, a unidirectional ..
volumetric fLow rate contr.ol valve is located in the hydraulic circuit between the two motors so th.at,.when the motors are i.:
operating in a relatively unloaded condition, one of the `-............ motors will rotate at a different rate. than the other to .
~i: 10 thereby cause the associated shaft to rotate. at a different ;`
:;,,. :
:~ rate than the other to promote.self-cleaning o~ accumulated ...
.:: rubber strips between the cutting devices on the two shafts.
,, ~ , : The invention also contemplates a bidirectional ~,.
.; pressure relief valve aaross the pump so that, should the :~1 reversing operation fail for any reason, a bypass circuit is ~: immediately established to preclude damage to. the components.
Other objects and advantages will become apparent from the following specification taken in connection with i~r~
~:f the accompanying drawings~
~ 20 : : DESCRIPTION OF THE DRAWING
,.. ~ ~ . .
Ihe P}gure is~a schematic illustr.ation of a tire ~;
~; shredding apparatus made~according to the invention. :
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DESCRIPTION OF THE PREFERRED EMBODIMENT
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~; An exemplary embodiment .o a tire shredding machine ;;j .:
made according to the invention is illustrated in the Figure ~1 and is seen to include two main components, including a ~ power pack, generally designated 10,. and a cutting apparatus, :.
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:lV374~8 generally designated 12, which may be, in practice, dis-posed some distance from each other.
Referring to the cutting apparatus 12, the same includes a cutting head, generally designated 14, which includes a cutter box 16 through which a pair of ~ ;
; parallel shafts 18 extend. The shafts 18 are rotatable ` `
and each mounts cuttiny and feeding means shown schematically _,',?.. ;~ ., at 20 which coact to feed, cut and shred tires in a manner ;
such as is well known in the common general knowledge of ~ 10 the art. j~;
':~ A pair of bidirectional hydraulic motors 22 and ;~ `
,~: j ,. ~ . , , 24 are respectively associated with the shaks 18, the `
arrangement being such that the shaEts 18 will be rotated '~ in opposite directions. The hydraulic motors 22 and 24 are connecked in parallel between hydraulic lines 26 and i~ 28. In normal operation, the line 26 will be the high ~-pressure line, while khe line 28 will be the low pressure line. However, this will not always be the case, as will be seen. In addition, each motor 22 and 24 1ncludes a 20~ ~ connection to a~drain line 30 which extends to a hydraulic fluid~reservoir 32 located within the power pack 10.
The line 26 includes, at a location between the motors 22 and 24,~a unidirectional, volumetric flow rate control valve~system, generally designated 34. The same ~ includes a flow control valve 36 which may be in the form ` ~
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., of a needle valve, and a check valve 38 connected in parallel. The flow control valve 36 is connected in the ~ - .
'. line so as ~o limit the volume of hydraulic fluid flowing -";-. . .
~ to the motor 24 while not restricting the volume of hyd- ~ ~
,~ .. . .
', raulic fluid flowing to the motor 22, when the line 26 is '', the high pressure line. When, however, the line 26 is .;`:~
,,,.". :, .
, the low pressure line and normal flow is reversed from .,~,,, the direction shown by the arrows of th.e Figure, the flow .. :, . . ,;
',~;. contr.ol valve 36 becomes ineffective by reason of the .. -;~r 10 parallel circuit including the check valve 38 which will `;
~ ,., ., ,. . ~ .
,",' open at that time.
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;:' As illustrated, the cutting apparatus also in-cludes a bidirectional, pressure relief valve 39 across ., the lines 26 and 28. While the valve 39 is shown as being ~
.~ located within the cutting apparatus, it .is to.be expressly .
~,~; understood that the same could be located in the power :;.
,~: pack 10 so long as the same is connected across lines 26 and '., ;r . 2&.
".,~ Flnally, the cutting apparatus 12 may includea stop-start switch 40 which is connected to the power pack ~.
10 by an electrloal line schematically illustrated at 42 .
for controlling the energization of the cutting head 14 as will ., be seen.
~ Turning now :to.the po~er pac~ .10,. th,e'same :in-;.,.~', cludes the hydraulic reservoir 32, as ment~i.oned pxeviousl~. ` The reservoix 32 receives oil ~xom the line 3~ and in-cludes an outl.et .line 44 including a il.ter ~6 to. a char~e '.:~
pump 48 for a bidirectional hydxaulic pump 50.o~ the swash .,;I, plate type. The pumps 48 and 50 are conventional and th.e '.,:i 30 latter is connected to. the lines 26 and 28 ta define a ,. .. ,~ ' . .J 6 ~.

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.;~ closed loop hydraulic circuit. The pump 50 may be driven :
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by a conventi.onal electric motor 54 having an electrical ... ~
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motor starting circuit .56 of conventional design. The ,`;
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~ starter circuit .56 is connected to the line 42 as well as :. ~
;., ~.. : .
;~;;.,: to a further stop-start switch 58. Thus, the motor 54 ':; can be energized or de-energized either at the location ~ .
,~ of the power pack or at the location of the cutting .
~: apparatus 12. '.. ` ;
Y, Returning to the pump 50, the same includes a ~; 10 swash plate control linkage 60 which is connected to the ~;.. ..
armature of a solenoid 62. When the linkage 60 is in the .. ~
,, , ;i,: dotted line position shown in the Figure, the line 26 will ~1 ,be the high pressure line. However, when the solenoid i9 j, .. energized to move the linkage to the solid line position I~
11!~, ' " ' .. shown in the Figure, the llne 28 will become the high pres- :i.
, sure line by reason of the change in position of the in- .~.
"~ ternal swash plate of the pump 50 reversing the direction ~, . . .. .. . .
~' of fluid flow.
; The solenoid 62 is connected electrically to be .~ .~
energized by~ a conventional time delay relay 64 which is ,i~:;
,, ~ : . ,.: :
powered by a low~voltage power supply 66 connected to the :~.
electrical motor starter circuit 56. Control of the relay ..
~"''!~ 64 is obtained from a pressure switch 68 which is connected `~:;
to sense the pressure in the line 26. ,~ . ;
r ,, . l Preferably, the pressure switch 68 is adjustable and is arranged so that when the pressure in the line 26 ,~ .
exceeds a predetermined value, it will energize the relay ~.
. ' 64 to in turn energize the solenoid 62 to shift the swash ,~l plate linkage 60 tQ the reverse position. The relay 64, ~l 30 being a time delay relay, will maintain the solenoid 62 ..
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energized for a predetermined time period notwithstanding '~
a drop in pressure in the line 26 which will occur upon ',~ reversal of the pump 50. Normally, the arrangement is such- that the solenoid 62 will be energized for several seconds. `
: , ,', The operation of the apparatus is as ; follows. Operation of either of the stop-start switches 40 or 58 will cause energization of the electrical motor to in turn drive the pump 50. Initially, fluid will 10w in ',, the direction of the arrows through the lines 26 and 28 to energize both the motors 22 and 24. Due to the presence of the flow control valve 36, under no-load conditions, the ~, motor 24 will rotate its associated shaft 18 at a lesser ''~;
,'~ rate than the rake o~ rotation o~ the shaft 18 associated ,, with the motor 22. For example, in one embodiment, under ,' no-load conditions, khe mokor 22 will rotate its sha~t , a,t appxoximately 42 rpm, while the motor 24 will rotate its '-,: :
shat ak approximately 22 rpm. `
It is apparent that the difference in ";
, rates of rotation will cause the feeding means on each of the s`'~ 20 shafts to tend to clear out accumulated rubber strips -~
:, ... .
~ ; caught between the cutting elements. Thus, the flow control '' valve 36 provides for the elimination of refuse between ,, , ; the cutting elements when the device is operating under a no-load condition.~
When a tire is introduced in-to the cutting box 16, the shafts 18 will continue to rotate to feed, cut and '~ shred the tire in the manner described above. EIowever, . l .
due to the coupling between the shafts 18 established by '' :', the presence of the tire, and the fact that the valve 36 ~',, `~
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'.~ restricts, flow but not operating pressure, during load ; :, :
~ conditi,ons, the mot-ors 22 and 24 will tend to drive their ;:.. .:.' ,., ~ . ~
~ shafts at the'same rate'of rotati.on.
: ,, - . : , i If ~he tire tends to,become jammed in the cutting '~;i; head, this will be reflected in an increase in pressure in ` the line 26. When the pressure builds up to the point "'' .'~';. where the motor 54 and pump 50 could be stalled, and thereby .
,;,~ .
',,., cause damage to the system, the pressure switch 68 will sense ~.; . :
, such an occurrence and throw :the system into reverse by '~'h ''' ',,~ 10 shifting the swash plate linkage 60. This will cause the ',;' :"
, motors 22 and 24 to rotate. their respective shafts in ;~
'1,' directions opposite that of the arrows shown in the Figure ,;
'.'''', with the result that.the tire will be moved backwardly and " ,~
~, 1 out of the cutting nip in the cutting head. Such action will ,~' ;;,; continue to occur for the period established by the time '.:'~.. :':' ,',, delay relay 64. Once'the relay 64 has timed out, the '',.... ,:
~ solenoid 62 will be de-energized with the result that the ,.. ~;.`,;:
,',j, swash plate linkage 60 will be returned to its forward ,'.
position thereby causing~the line'26 to again become the high .,:' '.;~
pressure:llne to rei'nLtiate cutting of the tire.: It ?.~'~" '''~;
is:to be noted that~the`presence of the check valve 38 '."'.~: insures that during:such::reverse~ energization of the system, ':-~"~"~ both motors 22 and;24~,w~ be driven at approximately the ,1,`
; : same rate, there being no res~triction on the volumetric : flow to the motor 24. The'purpose of this function is to `'., ,~;,1 insure rapid clearing of the'cutting nip. ., ~ !: It will also be observed that in the event the ~,,,`.; ~`
5"~ pressure switch 68 or the appurtenances thereto for re- ."~i`l~ '.'' ~ versing the direction of flow of hydraulic fluld in the , ",1 30 lines 26 and 28 fail, the pressure relief valve 39, which may ..
~ be set ,to. open at.a slightly higher pressure than the setting ~.,~ '`' :'~`i ~ 9 ~ , ';,, ,i'~'.` l '''" ' ' ; ,. :

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on the pressure switch 68, will open to.effectiveIy shunt ~,4 the flow of fluid to the motors 22 and 24 before the system ~.
can stall thereby precluding damage to the system.
It should be recognized that while electrical .
components are illustrated in the reversing system, the same action could be obtained through a hydromechanical linkage.
: It will also be observed that while a bidirectional ~.
hydraulic pump of the swash plate type is employed to ^.
: achieve reversing acti.on, a unidirecti.onal pump could be ..
.; lO employed in lieu thereb~ along with a four-way valve, if desired. ~
. From the foregoing, it will be appreaiated that ~
a shredding machine made according to the invention ~ possesses substantial advantages over the prior art ap-.:. paratus. For example, the same is constructed so that damage to an electrical drive motor such as the motor 54, `.
~; due to overloading cannot occur even when load sensing and reversing equipment~including the pressure switch 68 may fail. :It will also be observed that the system accomplishes, .
through the use of a flow control valve 36, a self-cleaning action w1thout the need for special mechanical components ,?`
to achieve this action. Moreover, the use of independent .
drives for the shafts 18 and the cutting head, eliminate the need for expensive, heavy duty gearing that would be subjected to substantial probability of ~ailure due to the high loading conditi.ons enaountered in tire shredding operati.ons. :

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A shredding machine comprising: a cutting head including a pair of generally parallel, rotatable shafts each having cutting and feeding means thereon; a pair of bidirectional, rotational output, hydraulic motors, one for each shaft, for rotating the shafts in opposite directions;
a hydraulic pump; means for driving said pump; conduit means connecting said pump to said motors in parallel and defining a closed loop; means associated with one of said pump and said conduit means operable to reverse the direction of flow of hydraulic fluid in said conduit means to thereby reverse the direction of rotation of said hydraulic motors; and pres-sure responsive means associated with said conduit means for sensing when the pressure therein exceeds a predetermined value for operating said reversing means for a predetermined period of time.

2. A shredding machine comprising: a cutting head including a pair of generally parallel, rotatable shafts each having cutting and feeding means thereon; a pair of bidirectional, rotational output, hydraulic motors, one for each shaft, for rotating the shafts in opposite directions;
a hydraulic pump; means for driving said pump; conduit means connecting said pump to said motors in parallel and defining a closed loop; means associated with one of said pump and said conduit means operable to reverse the direction of flow of hydraulic fluid in said conduit means to thereby reverse the direction of rotation of said hydraulic motors; pressure responsive means associated with said conduit means for sensing when the pressure therein exceeds a predetermined value for operating said reversing means for a predetermined period of time; and flow control means in said conduit means between said motors for limiting the volumetric flow rate to one of said hydraulic motors for one direction of fluid flow in said conduit means.

3. A shredding machine comprising: a cutting head including a pair of generally parallel, rotatable shafts each having cutting and feeding means thereon; a pair of bidirectional, rotational output, hydraulic motors, one for each shaft, for rotating the shafts in opposite directions; a hydraulic pump; means for driving said pump;
conduit means connecting said pump to said motors in parallel and defining a closed loop; means associated with one of said pump and said conduit means operable to reverse the direction of flow of hydraulic fluid in said conduit means to thereby reverse the direction of rotation of said hydraulic motors; pressure responsive means associated with said conduit means for sensing when the pressure therein exceeds a predetermined value for operating said reversing means for a predetermined period of time; and a bidirectional pressure relief valve connected to said conduit means across said pump and operable to establish a bypass for fluid flow when a predetermined pressure develops across said pump.

4. A shredding apparatus according to claim 3 further including a unidirectional volumetric fluid flow control valve in said conduit means between said motors for limiting the volumetric flow rate of hydraulic fluid to one of said motors for one direction of rotation thereof.