Note: Descriptions are shown in the official language in which they were submitted.
-~ ~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.
, : ~,; : ~ :
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
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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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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
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', : 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
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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
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~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
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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
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~67~
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
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~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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; 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
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~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
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:~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
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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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: ~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:
- :
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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'~ 15' `
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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