CA1067445A - Conveyor belt cleaning apparatus - Google Patents

Abstract

TITLE: "AN IMPROVEMENT I? OR RELATING TO
CONVEYOR BELT CLEARING APPARATUS"

ABSTRACT OF THE DISCLOSURE

Conveyor belt cleaning apparatus including a scraper member mounted for movement into engagement with a run of the conveyor belt, and including at least one fluid pressure actuated ram or torque motor for holding the scraper member against the belt when the conveyor is in operation.

Description

-~ ~0~44S

The invention relates to conveyor belt cleaning apparatus and has for its ob~ect to provide an improvement there.in.
In conveyor belt systems such as are used, for example, for the transportation of coal and mineral ores and other materials, ~elt cleaning apparatus is commonly provided having a scraper member bearing against the un~er-s~ide of the belt so that dirt is scraped off as the belt moves relative to the scraper member. The scraper mémber is commonly urged into engagement with the belt by. :~
resilient means, but:as the scraper member wears away and as stretch of the belt takes place it becomes necessary for ad~ustment to be made from time to time so as to maintain adequate pressure between the scraper member and belt. This . ~ :
inevitably involves a certain amount of trouble and incon-: venience.: The:lnvention alms to at least:~alleviate this.
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In accordance with the present invention, there is provided a conveyor belt cleaning apparatus, comprising:
at least one scraper membert respective carrier members to ~: 20 which opposite ends of the scraper member are secured; at . least one fluid pressure actuated device for maintainlng the scraper member with a scraper edge in engagement with ~: a run of a conveyor belt agalnst which it is arranged to :
, : bear with. a required pressure; a fluid pressure circuit to which the at least one fluid\pressure actuated device is connecte ; a fluid pump for maintaining a fluid pressure in the fluid pressure circuit whenever the conveyo~ is in operation; means for driving the fluid pump at least when the conveyor is in operation; and a cavity within the scraper member and spaced from the scraper edge, the cavity communicating with the fluid pressure circuit, the arrangement .; . i 1 :
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~067~5 being such that when the scraper edge becomes worn down to such an extent that the scraper member needs to be replaced the cavity within the scraper member ~ecomes ruptured whereby fluid under pressure is allowed to escape from the fluid pressure circuit so that the scraper member is allowed to move away from the fonveyor belt.
~ In order that the invention may be fully understood and readily carried into effect, the same will now be ` described, by way of example only, with reference to the accompanying drawings, of which:
Figure 1 is a perspective schematic view of apparatus embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure 1, Figure 3 is a sectional view on the line 3-3 in Figure 2, Figure 4 is a perspective view of different apparatus embodying the invention, Figure 5 is an exploded view of the component parts at one side of the apparatus, and Figure 6 is a diagrammatic view of a pneumatic control circuit which will presently be referred to.

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~0674~5 Referring now to ~igs. 1 to 3 o~ -the drawings, apparatus for cleaning a conveyor belt (shown in chain-dotted lines in ~ig. 1~ includes a scraper member generally indicatcd 10 secured at its opposite ends to carrier members constituted by respective leaf springs 12 so as to bcar against the underside of the belt.
The lea~ springs are mounted at their ends remote ~rom the scraper member. on respective carriers 14 which are freely mounted ~or pi~otal mo~ement abo~t an axis 16, Respective pneuma-tic rams .
18 are connected, as .shown, to the free ends of -the carriers 14 and are connected in a pneumatic circuit which also includes a pn~umatic accumulator 20 and : 15 a pneumatic pump 22 driven by:an electric mator 24.
~he arrangement is such that whenever *he conveyor is in operation the electric motor drives the pump , .
: 22 and maintains a substantially constant pressure of : ,~
', : air in the accumulator 200 ~he pressure within the , accumulatox acts equally in tke -two pneumatic rams so :::
that when the conveyor is in operation the scraper member is maintained in engagemen-t with -the run of : the belt against which it is arranged to bear with a required substantially constant pressure ~despi-te wear , ; 25 o~ the scraper member and stretch of the belt). It will also be understood that the ar_angemen-t is such that _ ,~

leakage of air from the system allows the scraper member to fall away from the conve~or bel-t~
aonsequently, when the conveyor has been stationary ~or some time, the scraper member will hav& fallen away from the conveyor belt and -the conveyor can be re-started more easily than if the scraper member had remained in engagement with the belt~ After only a ver~ short period of subsequent operation the air pressure within the system is re-established so that the scraper member moves back into contact with the belt. ~he fact that this occurs quite automat-ically and without the need for operator control is a very useful feature of the invention. It will also be u~derstood that since the apparatus maintains the scraper member in contact with the belt with a substantially constant pressure despite wear of the scraper member and stretch of the belt, the apparatus will only require~adjusbment ab very long intervals of time.
Referring now m particular to Figs. 2 and 3, it will be seen -that the scraper member is formed so that it provides two soraper edges which can be brought into use selectively by adjusting the scraper member in position at a required angle relative to respective carrier plates 26 which are bolted to the free ends of the leaf springsa ~he scraper member -~C~67445 is secured at its opposite cnds to the respective ; carrier plates by means including respective taper plug and socket ~ixings generally indicated 28.
~aper socket portions 30 of said ~ixings project inwardly towards the scraper member ~rom the respective carrier plates to which they are welded as shown in Flgo 3. ~aper plug portions 32 of said fixings on the other hand project outwardly from a central hole 34 which extends through the scraper member and . .
engage the taper socket portions. Screw means, constituted by respective bolts 36 (only one of which is shown in Fig. ~) one of which has a right hand thread and the other of which has a left hana ~, thread, are provided ~or -tightening the taper plug and socket fixings and securing the scraper member ~-~ at a required angle.
;It will also be seen from Figs~ 2 and 3 that the scraper member i,s provided with respective ~
cavities 38 which extend longitudinally of the member and which are spaced appropriate distances from the respective scraper edges~ When the edges have been worn away so that the cavities are bro~en into, as shown by the chain dotted line W in Fig. 2, it is time for the scraper member to be re-adjusted to bring the other edge lnto operation or for the re-placement of the scraper member by a new one. Air .3 ~;

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under pressure in the control system is able to communicate with the cavity 38 adjacent that scraper edge which for the time being is in use by way of a flexible conduit 40 which is shown ex*ending along one of the leaf springs and connected to one of the pneumatic rams 18 (but it will be understood that it could be connected into any part of the system). ~he arrangemen-t is such that when the soraper edge which is in use becomes so badly worn down that the adjacent cavity 38 is broken into, the sudden massive loss of air from the control system through -the e}~osed cavity cannot be compensated for by the relatively small deliver~ of air from the pump and thus the pneumatic rams are allowcd to retract and the scraper member is consequently allowed to fall away ~rom the conveyor beltO A pressure switch (not shown) is provided in the control system and is arranged to operate an audible and/or visible alarm in the event of a sudden loss of pneumatic prcssure.
An operative oan then re-position or replace the worn scraper member as re~uired.
As shown in Fig~ 3, the flexible conduit 40 communicates with the cavity adjacent the scraper edge which is for the time being in use through a hole 42 which extends through the socket portion 30 of the adjacent fixing 28. ~he hole 42 is automat-ically oaused -to communicate wi-th the correct one of .

~6~67~45 two oppositely located feed ports 44 in -the taper plug portion 32, -to communicate with the c~rrect one o~ the two cavities 38, as the scraper member is adjusted in posi-tion to bring the required scraper edge into use. ~he ends of cross drillings 46 and the ends of the cavities 38 are shown to have been plugged at 48.
Referring now to ~igs. 4 and 5~ in a rather different apparatus embodying the inven-tion? a pair of scraper assemblies 110 and 112 are mounted one in ~: advance of the other between respective pairs of holders 114 and 116 carried by locating arms constit~ted by groups o~ leaf springs 118 and 120 so that said soraper assemblies bear against the underside o~ a conveyor belt ~shown in chain-dotted lines) resiliently.
. The leaf springs are mounted at their ends : remot~ from the scraper members on respective carriers 122, 124 and 126~ 128 which are freely rotatable on co-axial sha~ts 130 and 13~ and screw means cons-tituted by respcctivc pairs of screws 134 and 136 are provided ~or acting against the pairs o~ carriers to load the ~: scraper assemblies against the co~veyor belt which they are to clean. ~hc screw mcans referrcd ~o are carried by a single pair of brackets 138 and 140, each such bracket being located between the carricrs ~ against which its screw means act and having a :

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~ ~ 6~ ~ ~ 5 ; hexagonal bore for receiving, non-rotatably, an inner end of the hexagonal section sha~t on which it is mounted~ Each bracket 138 ~h~ O has a pair of laterally extending plate elemen~s 142 through which the screws 134 and 136 extend at the spacing of the carriers 122 and 124, said screws being located m ad~usted positions by locknuts 144. The outer end of each hexagonal section sha~t i.s provided with a lever 146 a boss portion of which is a sliding non-rotatable fit on the sha~t.
~ixing bracke-ts 148 ~ 5~ are provided ~or mounting the oleaning apparatus on fixe.d frame ~
structure (not shown) of a conveyor, said brackets including apertured plates 152 for bolting to said fixed ~rame structure and also including lengths of tube 154:on:the outer en~s o~ which respective : circular pla~e members 156 and 158 are welded.
Respective mounting brackets 162 and 164 are : bolted to the plate members 156 and 158 as shown and have forked outer ends in which the cylinders of respective double acting pneumatic rams 166 and 168 are trunnion mounted as sho~n. ~he piston rods .
170 of the pneumatic rams are pivotally connected :~: to the outer ends of the respective levers 146.
25 Respective pairs of cavities 172 and 173 extend longitudinally of the scraper members 110 and 112 as shown in Fig. ~and respective conduits 174 ,r~
. 5 ~ ~ _ ~67~;45 and 176 are conne~ted into said cavities at one sid.e of the apparatus (the ends of the cavities at the other side of the apparatus having been plugged), ~he aonduits communicate wi-~h a control system which is 5 shown diagrammatically in Fig~ 6.
Referring now -to ~igo 6~ the control system includes a key operated control valve 178; a pair OI
spool valves 180 and 182 under the control of respective auxiliary valves 184 and 186; respective manually operable re-set valves 188 and 190 commun-auxiliary icating with said / valves; a pressure regulator 192; a pressure gauge 194; respective flow con-trol valves 196 and 198 in the conduits 174 and 176 which ~ communicate with the cavities in the scraper members;
:, 15 and three pressure switohes 200~ 202 and 204 which are arranged to close electric circuits incIuding :~l respective electric light bulbs 206, 208 and 210 coloured, green, amber and redO
The operation of the control system is as 20 follows:-When the key operated control valve is opened;
air under pressure can pass from a main supply line 212 into a fecd line 214 which communicates with the spool valves 180 and 182 and with the re-set valves 188 and 1909 ~he air pressure in the feed line is indicated by the pressurc gauge 194 and canbe adjusted "

:~067~5 by the xegulator 192. (~he presence of air under pressure in the mai~ supply line 212 is indicated by the closure of thc pressure switch 200 and the non-illumina-tion of the green light bulb 206)~ ~he re-set valves 188 and 190 must then be opened momentarily by pressing the push buttons associated with them. ~his allo~s air under pressure to pass to the auxiliary vaives 184 and 186 whioh causes their associated ` spool val:~es to open so ~hat air under pressure can i 10 pass through said respective spool valves into the conduits which communicate with the cavities in the scraper member. Simultaneously, the pressure switches 202 and 204, which communicat~ as shown with the conduits 174 and 176 respectiv~y, cause the electric 15~ lights 20B~and 210~to be open circuited, and the pneumatic rams 166 which communicat~ with bhe conduits 176 are actuated so that they urgc the scraper member ; into engagement with the conveyor belt~
After a period of prolonged use the scraper members will become worn down to such an ex*ent that the cavity 172 in one or the other of them will be ~ptured to allow the escape of air under pressure from a part of the con-trol system, that is to say from the scraper side of the flow control valve 196A
Air under pressure will thus be released from the auxiliary valve 184 and the spool valve 180 will be '` :

7~5 able to close under spring pressure. Consequently7 -the pressure switch 202 will be allowed to close and tlle amber light bulb 208 will be i:Lluminatea to indica-te that the scraper members should be replaced or that they should very shortly be replacedO However~
a~ter a ~urther period of use the cavity 173 in one or the other o~ -the scraper members will be ruptured and this will allow the escape of air under pressure from another part of the control system, tha-t is to say from the scraper side of the ~low con-trol valve 198. Air under pressure will thus be released from the auxiliary valve ~86 and the spool valve 1~2 will be able to close under spring pressure. Simultaneously, the air under pressure in the pneumatic rams will be allowed to escape and the scraper members will ~all away from the conveyor belt. An indication o~
this will be immediately given by the closure of -the pressure switch 204 causing the red light bulb 210 , to be îlluminated~
Before a workDIan star~s to replace tlle worn scraper members, he will close the key operated valve 178 so that air under pressure can communicate with a feed line 216 -to positively retract the double acting rams and hold the scraper members away from the convcyor beltO
I-t will be understood that -the loss of air - ?~
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67~5 u~der pressure ~rom the control system will be minimal and of very short duration following the rupture of the cavities 172 and following the rupture o~ the cavities 173. It will also be unaerstooa that when the scraper membcrs have moved away from the conveyor belt the apparatus will remain in this condition until the worn scraper members have been replaced and the re-set valves operated.
~he condition o~ the apparatus can be ascer-tained by observing the light bulbs 206~ 208 and 210 which of course can be located near the apparatus or at some remote location as requiredO It will also be understood that the electric circuits containing the light bulbs may contain or be associated with Pu~ther warning means9 for example audible alarms, and that a quite strident wa~ning may be given when the apparatus is no longer operable due to excessive wear of the : scraper members or failure of the air supplyO
Various modifications may be made without ; 20 departing from the scope of the invention. For example, the scr~per members of the arrangement illustrated could if preferrec1 be provided with two or three scraper edgos capable of being brought into use selectively ~urthcrmore, each scraper member could be provided with only a single cavity whicll when rup-tured causcd a warn;ng signal to be given or 1~:)67~45 caused the scraper members to be moved away from the conveyor belt. ~he arrangement ma~ be such tha-t the condition of the scraper member or members can be indicated at some remote location (for example in an office building) so that the need for replacement of a worn scraper member ca~ be ascertained with the minimum o~ trouble and inconvenience~ In the case of a scraper member with a pair o~ cavities which will become ru~tured in succession, an indication that a first one of the cavities has recently become ruptured may be taken to mean that the scraper member can continuc in use for the time being bu-t that arrangemcnts must be made for its replacement within~
say~ one week of further use. It should also be ~` 15 understood that the scraper member or members need not necessarily be acted upon by hydraulic or pneumatic rams to maintain the scraper member in : engagement:with a run of a conveyor belt against which it is arranged to bear with a required pressure.
A so-called torque motor could be provided to exert a pre-determined torque on a shaft from which the carrier members project (or a pair of such torque motors could be providcd to act on respective shafts) and in this case the or each torque motor could act against the shaft on which it is arranged to exert a torque by means of a pinion meshing with a gear segment~
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~C~6~ 5 : ~he working medium of the eontrol ~ystem could of course be hydraulic fluid instead of air : under pressure but it would probabl~ not be , desirable to allow the leakage of hydraulic fluid~
even though thls might only be a very small ; quantity of ~luid, ~rom the system -to indicate excessive wear of the scraper member. It might be thought desirable~in such a situation to either omit:
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the feature of the:working fluid being contained 10 ~ unaer pressure in the scraper member or alternatl~ely ~;
~ to lneorporate a dua} cireult arrangement, that i6 : ~ ~ to say to have hydraulic~fluid in a first circuit eontaining the rams or torque motor ~or raising th~ .
scraper member i.nto engagement with the belt and to have air~under pressure in~a second~circuit;communic~ ~ ~
a~:ing~with:the~ oavity:adaacent the scraper edge which~ ;
s~for the~;tlme~be1ng in~use, the~two circuits being ~ :
interconnected, that~ls to say a sudden drop o~f pressure~in the air circuit causing a sudden drop of 20~ pressure in the hydraulic circuit and stoppage of~the hycl1:aulic pump. A hydraulie or pneumatic pump for charging the contro1 circuit (or each pump if a dual:
~::: circuit arràngement~is used) may be clriven by a roller in contact~with the oonveyor be~t lnstead of by an electric motor. ~he carrier members are preferably ~: ~
~ constitu~ed by respective leaf springs so that the : ` : ~ :

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3~06~ 5 or each scraper membcr is held against th~ conveyor belt resiliently. Xowever, -this ls not essential~
especially if thc working ~luid in -the control system is air under pressure~ which is of course ` compressible.

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Claims (6)

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

1. A conveyor belt cleaning apparatus, comprising:
at least one scraper member; respective carrier members to which opposite ends of the scraper member are secured; at least one fluid pressure actuated device for maintaining the scraper member with a scraper edge in engagement with a run of a conveyor belt against which it is arranged to bear with a required pressure; a fluid pressure circuit to which the at least one fluid pressure actuated device is connected; a fluid pump for maintaining a fluid pressure in the fluid pressure circuit whenever the conveyor is in operation; means for driving said fluid pump at least when the conveyor is in operation; and a cavity within the scraper member and spaced from the scraper edge, said cavity commun-icating with the fluid pressure circuit, the arrangement being such that when the scraper edge becomes worn down to such an extent that the scraper member needs to be replaced the cavity within the scraper member becomes ruptured whereby fluid under pressure is allowed to escape from the fluid pressure circuit so that the scraper member is allowed to move away from the conveyor belt.

2. The apparatus of claim 1, wherein said at least one scraper member is provided with at least two scraper edges which can be brought into use collectively as wear takes place, and is provided with respective cavities spaced appropriate distances from the respective edges, the appropriate cavity being placed in communication with the fluid under pressure in the control system as the scraper member is being adjusted to bring a selected scraper edge into use.

3. The apparatus of claim 1, wherein said at least one scraper member is provided with a pair of cavities spaced different distances from the at least one scraper edge, and further including means associated with said fluid pressure circuit for giving warning signals in response to a loss of fluid pressure from said pair of cavities, the arrangement being such that as the at least one scraper edge wears away a first cavity becomes ruptured to give an initial warning that said at least one scraper edge is becoming excessively worn and after further wear a second cavity becomes ruptured to give a more strident warning to indicate that the at least one scraper edge has become excessively worn.

4. The apparatus of claim 1, including at least two scraper assemblies mounted one in advance of the other between their respective carrier members, the latter being mounted at their ends remote from their respective scraper members on respective carriers pivotally mounted for angular adjustment about a common axis, means being provided for acting against the pairs of carriers selectively so that the respective scraper assemblies are loaded selectively against the conveyor belt which they are to clean when the at least one fluid pressure actuated device operates to maintain the scraper assemblies in engagement with the belt.

5. The apparatus of claim 4, wherein the pairs of carriers on which the respective pairs of carrier members are mounted are freely rotatable on a shaft and in which the means provided for acting against the pairs of carriers to load the respective scraper assemblies against the conveyor belt which they are to clean are constituted by respective screw means.

6. The apparatus of claim 1, including respective fixing brackets which can be secured in alignment to frame structure of the conveyor on opposite sides of the belt, mounting means for respective pneumatic rams, and means whereby the fixing brackets and said mounting means for the respective pneumatic rams can be interengaged in any one of a plurality of different angular positions.