Note: Descriptions are shown in the official language in which they were submitted.
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PATENT APPLICATION OF MICHEL LESSARD
FOR A
SKIMMING DEVICB
FIELD OF THE INVBNTION
The present invention relates to the field of skimming devices and is p~ ul~ly
concerned with a device for skimming impurities floating on top of a volume of liqnid.
BACKGROUND OF THE INVENTION
Various situations exist wherein it is desirable to remove debris floating on the top
surface of a volume of liquid. One example of such situation is ~ o...lL-,Icd in the
industrial process leading to the formation of ingots made of aluminum.
The production of aluminium ingots typically requires three major steps, namely the
formation of melted aluminum in so called electrolytic tanks, the casting of the melted
aluminum into solid ingots at a casting site and the ~ I ;(." of the melted aluminum
from the cl.,.ll~,lyli~. tanks to the casting site.
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The melted aluminum is formed by a continuous process m the electrolytic tanks through
the clc~llul.y~iD of am alumina bath or aluminum oxide bath containing dissolvedaluminum oxide. The aluminum onoe formed being more dense than the alumina bath,it sinks to the bottom of the electrolysis tank.
Since the melted aluminum is formed through the use of a continuous process and since
the melted aluminum rests underneath a layer of alumina bath, the melted aluminum is
cyclically transferred out of the electrolysis tank using a siphoning process that siphons
the melted aluminum into so called crucibles.
Each crucible typically consists in a cylindrical open top container made of steel and lined
with refractory bricks. These crucibles are mounted on conveyer belts amd act ascontainers for 11~ the newly formed melted aluminum from the electrolysis tank
to the casting location and for allowing thc newly formed melted aluminum to cool down
and attain an ideal cooling I . ~ before reaching the casting site.
During the siphoning process of the liquid aluminum from the electrolysis tank to a given
crucible, some of the overlying electrolysis bath is also, r; ~ ~y siphoned into the
crucible. The fusion i . ~i of the electrolysis bath being higher tham that of the
newly formed melted aluminum, when the liquid content of a crucible cools down, the
aluminum bath solidifies atop the newly formed melted aluminum thus forming a layer
of froth. This layer of froth must, of course, be removed from the crucible prior to the
8 ~
aluminum being poured into the casting molds.
The traditional method of removing the layer of froth from the surface of the cooling
melted aluminum consists in dipping a large perforated spoon into the liquid metal and
manually retrieving the solidified pieces of electrolysis bath.
The spoons being heavy and the I . ~ in the vicinity of the crucible being elevated,
the manual operation is non-ergonomic and may potentially lead to injury. Fu~ o~c;,
dipping of the spoon into the crucible may cause splashing of its content on the operator
lo again potentially causing serious injuries.
Accordingly, there exists a need for a device that could ~ / remove debris
floating on top of a volume of liquid.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a ' ~ I skimmmg device.
Advantages of the present invention include the fact that the ' ' skimming device
in accordance with the present invention removes debris floating on top of a volume of
liquid therefore reducing mamual labor and the associated health hazards.
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The skimming device in accordance with the present invention also provides means for
~ g the: of the liquid being skimmed by impurities.
The skimming device in accordance with the present invention provides efficient sealing
meams so as to prevent the material being skimmed off the layer of liquid from
L.~ till~;ly dripping out of the skimming device.
The skimming device in accordance with the present invention is provided with
(Y~ . .a~ that are specifically designed to prevent jamming of the various moving
, , when the device is used with solidifying material.
In accordance with one aspect of the invention, there is provided a skimming device for
skimming debris floating on a volume of liquid, the skimming device . u . g a base
member; a spacing arm, the spacing arm having a spacing arm proximal end and a
spacing arm distal end, the spacing arm proximal end being attached to the base member;
a bucket component attached to the spacing arm distal end, the bucket component having
a pair of jaw members; each of the jaw members having a jaw member base walls and
a jaw member peripheral wall; the jaw member base wall defining a peripheral edge free
segment and a peripheral edge walled segment, the jaw member peripheral wall extending
from the peripheral edge walled segment; the jaw member peripheral wall having aperipheral wall proximal end and a peripheral wall distal end; the jaw members being
pivotal relatively to one another about a jaw first pivoting axis between a jaw member
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first position and a jaw member second position, wherein when the jaw members are in
the jaw member first position, they fonn an open top container with the peripheral edge
free segment and the peripheral wall distal end of one jaw member contacting the
peripheral edge free segment and peripheral wall distal end of the other jaw member, and
wherein when the jaw members are in the jaw member second position, the peripheral
edge free segment and the peripheral wall distal end of one of the jaw members are
spaced from the peripheral edge free segment and peripheral wall distal end of the
opposed jaw member.
Preferrably, the skimming device further comprises a jaw pivoting means for pivoting the
jaw members between the jaw member first position and the jaw member second position.
IPi~l-tly, each of the jaw member base walls defines a base wall upper surface and
a base wall lower surface, the jaw mcmbers further comprising a deflecting plate the
deflecting plate being mounted undcrneath the base wall lower surface amd angled
relatively to the latter.
Preferrably, the jaw member base wall has a substantially triangular . .,.,ri~ ", the
peripheral edge free segment having a substamtially straight ~ r~ , the peripheral
edge free segment extending between a free segment proximal end and a frcc scgmcnt
distal end, the peripheral edge walled segment defining a walled side segment and a
walled front segment, the walled side segment having a substantially straight ~ ' ~
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and a length . ' 'Iy equal to that of the peripheral edge free segment, thc walled
side segment having a side segment proximal end and a side segment distal end, the
walled side segment being angled relatively to the peripheral edge free segment so lhat
the free segment proximal end connects with the walled segment proximal end at an edge
hlt~,l.,~ plil.g corner and the free segment distal end is spaced from the walled segment
distal end, the walled front segment extendmg between the free segment distal end and
the walled segment distal end.
Co.... - Iy, one of the walled segment distal end extends into a walled segment
u~ ,uh.L lip, the walled segment overlapping lip being configured and sized so as to
overlap the walled segment distal end of the other jaw member when the jaw members
are in the jaw member closed, '~
Preferrably, the spacing arm proximal end is pivotally attached to the base member so as
to allow the spacing arm to pivot about a spacing arm first pivoting axis, the spacing arm
first pivoting axis having a: I - 'Iy horizontal orientation.
Cu ~ " the skimming device further includes a stabilizing means for preventing the
tilting of the bucket compûnent when the arm is pivoted about the arm first pivoting axis.
In one , '.o.l: .1 ofthe invention, the stabilizing means takes the form of an auxiliary
arm rotatably attached at one end thereof to the bucket cûmponent and rotatably attached
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at its opposed Inng;f U~ end to a spacing component extending from the base member,
the au~iliary arm being in a parallel l~laliO..~h.~) relatively to the arm.
In another ' ' of the invention, the stabilizing means is a stabilizing piston
attached at one of its l~.,,v~ end to the arm and at its opposed 1( ~ ' ' end tothe bucket ~ ,
G~llv~,lli.,lllly, the arm proximal end is mounted on a turntable component for allowing
the arm pro~imal end to pivot about an arm second pivotal axis, the arm second pivotal
o axis being in I - 'Iy vertical orientation.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1: in an elevational view, illustrates a skimming device in accordance with an
of the present invention, the skimming device being shown with its jaws
dipped into a crucible, the crucible being shown in cross-section;
Figure 2: in a perspective view, illustrates a pair of jaw members part of a skimming
device in accordance with am ' ~' of the present invention, the jaw members
being shown in a partially opened, r~
Figure 3: in a perspective view, illustrates a pair of jaw members part of a skimming
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device in accordance with an r.n ~- ~ of the present invention, the jaw members
being shown in a partially opened ..-.. .r;v., -~ i.l hidden lines are sown in phamtom lines;
Figure 4: in a perspective view, illustrates the jaw members of Figure 2 in a fully opened
c/~nfig~ ion;
Figure 5: in a perspective view, illustrates the jaw members of Figure 2 in a fully opened
riV.~ " the hiden lines being shown in phamtom lines;
lo Figure 6: in an elevational view, illustrates the jaw members of Figure 2 in a fully opened
"V the hiden lines being shown in phamtom lines;
Figure 7: in a side view, illustrates the jaw members of Figure 2 in a fully opened
'v the hiden lines being shown in phamtom lines;
Figure 8: in a side view, illustrates a skimming device m accordance with an embodiment
of the present invention, the skimming device being shown with its jaws in a partially
opened ~r."riV ~ ., dipped into a crucible, the crucible being shown in cross-section;
Figure 9: in a top view, illustrates a skimming device in accordance with an, bo,'
of the present invention, the skimming device being shown with its jaws moving between
am open and a closed, '_ and its arm pivoting out of position relatively to the
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crucible;
Figure 10: in an elevational view illustrates a skimming device in accordance with a
second cll.bodi...~ t of the present invention;
Figure 11: rn am elevational view illustrates a skimming device in accordance with a
second ~,~b~: " of the present invention, the skimming device being shown in a
working ~,llVil~ ' and with an enlarged detail view of a i . ~ display.
DETAILED DESCRIPTION
Referring to Figure 1, there is shown a skimming device 10 in accordance with an
of the present invention. The skimming device 10 includes a base member
12, a spacing arm 14 and a bucket component 16.
The spacing arm 14 has a spacing arm proximal end 18 and spacing distal end 20. The
spacmg arm proximal end 18 is attached to the base member 12 while the bucket
component 16 is attached to the spacing arm distal end 20.
Referring now more specifically to Figures 2 through 7, the bucket component 16 has a
pair of jaw member 22. Each of the jaw members 22 has a jaw member base wall 24 and
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a jaw member peripheral wall 26. The jaw membcrs 22 are mouneed to the spacing arm
distal end 20 so as to be pivotable relatively to one another about a jaw member pivoting
axis 28 as will be hereinafter disclosed.
The jaw member base wall 24 has a base wall peripheral edge defining a peripheral edge
free segment 30 amd a peripheral edge walled segment 32. The peripheral wall 26
extends s ~ 'Iy upwardly from the peripheral edge walled segment 32. The jaw
member peripheral wall 26 has a peripheral wall proximal end 34 and a peripheral wall
distal end 36.
The jaw members 22 are pivotable relatively to one another about the jaw pivoting axis
28. The jaw pivoting axis 28 extends in a drrection substantially ~ Ji~,ulal to the jaw
member base wall 24. The jaw members 22 are pivotable between a jaw member firstposition and a jaw member second position. Figures 2 and 3 illustrate the jaw members
22 in a position close to the jaw member first position while figures 4 through 7 illustrate
the jaw members 22 in the jaw member second position.
When the jaw members 22 are in the jaw member first position, they form an open top
container with the peripheral edge free segment 30 and the peripheral wall distal end 36
of one jaw member 22 contacting the peripheral edge free segment 30 and the perip]heral
wall distal end 36 of the other jaw member 22.
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As illustrated in Figures 4 through 7, when the jaw members 22 are in the jaw member
open position, the peripheral edge free segments 30 and the ~Oll~ ~ ' g peripheral wall
distal ends 36 are spaced relatively to one another and, preferably, for reason
hereinafter disclosed, the outer surface of peripheral walls 26 abuttingly contact each
other.
The buckct component 16 preferably further includes a deflecting means for deflecting
the debris away from the bucket component 16 when the latter is put into contact with
the top surface of a volume of liquid. The deflecting means typically takes the forrm of
a pair of deflecting plates 38, each deflecting plate 38 being fixed underneath the lower
surface of a COll~ r ' ~ base plate 24 and angled elatively to the latter.
The deflecting plates 38 are typically kept in a partially spaced apart and angled
l~ Idiu~ J relatively to the ~ Ull~ ~t,ollJi,lg jaw member base wall 24 by a l~,h~ul~~ llt
rib 40 extending Lh.,l~b.,h. ~ ~"1. Typically, each deflecting plate 38 is angled away from
the ..o.,. ~ ",.~ g jaw member base wall in a direction leadmg from the ~II~.S~JUIId;ll~;
peripheral edge free segment 30 towards the peripheral edge walled segment 32.
The jaw member base wall 24 preferably has a ~ ~ ~Iy triangular ~ in.. In
such instancel the peripheral edge free segment 30 has a ' 'Iy straight
r;~ ,;"" The peripheral edge free segment extends between a frec segment
proximal end 42 and a free segment distal end 44. When the jaw member base wall 24
~ 218068Q
has a ' 'ly tdangular ~ r;~ the pcriphe}al edgc walled segment 32 defines
a walled side segment 46 and a walled front segment 48.
The walled side segment has a substantially straight ~ onfi1 and a length
$..h~ lly equal to that of the peripheral edge free segment 30. The walled side
segment 46 has a side segment proximal end 50 and a side segment distal end 52. In fact,
when, the jaw member base wall 24 has a substantially triangular, r~ the
side segment proximal end 50 coincides with the peripheral wall proximal end 34.
The walled side segment 46 is angled relatively to the peripheral edge free segment 30
so that the free segment proximal end 42 connects with the walled segment proximal end
50 at an edge h-l~l~!JI;..~ corner. The free segment distal end 44 is spaced from the
walled segment distal end 52.
The walled front segment 48 extends between the free segment distal end 44 and the
walled segment distal end 52. The jaw pivoting axis 28 is typically located adjacent the
edge ~-tillg corner. In an alternative e~ '' of the invention the walled front
segment 44 has a generally arcuate, ~ .
The jaw members 22, as will be hereinafter disclosed, are adaptcd to act as a pair of
scooping jaws for skimming the impurities floating on top of a volume of liquid and
retaining these impurities until they can be dropped into an dl)~)10~ ' ' waste recepLIcle.
1-- 2180680
A sealing means is thus provided for preventing the debris having being scooped off the
top surface of the volume of liquid from escaping the bucket component formed by the
jaw members intheir closed position.
The sealing means typically takes the form of a walled segment o.~lla,u,uilJg lip 54 that
extends integrally from the walled segment distal end 44 of one of the jaw mcmbers.
The walled segment uv. ' Il g lip is configured in size so as to overlap the walled
segment distal end 44 of the opposing jaw members when the jaw members are in the jaw
member closed position.
Preferably, the sealing means further includes a free segment u -~1 r I ~ ~ lip 56 extending
integrally from the peripheral edge free segments 30. The free segment u.vlla~ lip
56 is configured in size so as to overlap the peripheral edge free segment 30 of the
opposed jaw member 22 when both jaw membcrs 22 are in the jaw member closed
position.
Typically, bûth the walled segments u . . ' 1 . ~ g lip 54 and the free segment u . ~ lla~J~;.Ig
lip have a C.lh5f~ y "L"-shaped rr,nfiellr~tirr~ defining an outward spacing segment
and an abutting segment. The abutting segment being adapted to abuttingly overlap the
opposed structure when the jaw members 22 are in the jaw member closed position.
In order to facilitate both the scooping of debris floating on the top surface of a volume
~ 21806g~
of liquid and to facilitate the discharge of the debris from the bucket component to a
suitable disposal site or container, the jaw member base wall 24 are preferable angled
relatively to an horizontal plane with the peripheral edge walled segment 32 being located
above the peripheral edge free segment 30.
As mentioned previously, the jaw members 22 are mounted on the distal end 20 of the
arm 14 so as to allow their relative pivotal movement between the jaw open l-nnfigu~ ~ n
and the jaw closed ~ ~,..r:".., ~i,-" In the preferred ~ o~ 1, one of the jaw members
22 is fixed while the opposed jaw member 22 is pivotable.
As illustrated more specifically in figure 8, the pivotable jaw member 22 is attached to
a jaw shaft 58 that extends through a jaw sleeve 60 to which the fixed jaw member 22
is attached. The jaw shaft 58 is coupled by a . C~ liOIIal coupling sleeves 62 to a
rotating power means such as a co.~, ' motor 64. The jaw shaft 58 and the jaw
sleeve 60 are specifically designed so as to prevent jamming of the jaw membres 22 when
the aluminium solidifies.
The jaws 22 are preferably attached to an auxiliary jaw shaft 66 mounted in an auxiliary
jaw sleeves 68 so as to allow pivotal movement of the jaw members 22 about a second
jaw member pivoting axis 70. The auxiliary jaw shaft 66 amd the auxiliary jaw slceve
68 are typically mounted on the distal end 20 of the arm 14 in a cnhS~nti~lly
1~ .I,.. l:. ~ '~ I~ ' ', relatively to the latter and are adapted to allow the jaw
14
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members 22 to remain in a s ~ ' 'ly constant horizontal orientation regardless of the
angular p~ ~t; ~ ~ of the arm 14 as will be hereinafter disclosed.
As illustrated in figure 1, the proximal end 18 of the arm 14 is pivotally attached to an
arm mounting structure 72. The arm mounting structure 72 is, in turn, mounted on a turn
table ~ l 74. The proximal end 18 of the arm 14 is pivotally attached to arm
mounting structure 72 so as to allow a pivotal movement of the arm 14 about an arm
pivoting axis 76.
0 A pivoting means preferably taking the form of a Wllv~ piston component 78 is
attached to both to the arm 14 and to the arm mounting structure 72. The piston
component 78 is adapted to pivot the arm proximal end 18 about the arm pivoting axis
76 so as to allow the bucket component 16 to be raised or lowered as will be hereinafter
disclosed.
A stabilizing means is provided for preventing the bucket component 16 from being tilted
when raised or lowered by a pivotal action of the arm 14 above the arm pivoting axis 76.
In the first f~ml~~ ' ' of the invention, the stabilizing meams takes the form of an
auxiliary arm 80. The auxiliary arm 80 is pivotally attached at a distal end thereof to
a linkage arm 82.
The auxiliary arm 80 is attached at a proximal end thereof to an upwardly protuding
~ 2180~8~
scgment 84 of the arm mounting structure 72. The linkage arm 82 is attached to auxiliary
jaw shaft 66 and adapted to transmit rotational movement to the latter.
The auxiliary arrn 80 is mounted in a parallel ll l ~ ' . to the arm 14 and pivotally
attached at both ends so as to rcmain in a parallel ll l ' " with the arm 14 when the
latter is pivoted about its arm pivoting axis 76. The parallelogram formed by the arm 14,
the auxiliary arm 80 the linkage arm 82 and the protuding segment 84 of the arm
mounting structure 72 is thus adapted to prevent tilting of the bucket component 16 when
the latter is either raised or lowered by a rotational movement of the proximal end 1~ of
o the shaft 14 about its shaft rotating axis 76.
In a second .,lllb. ' of the invention illustrated in Figure 10, the stabilizing means
takes the form of a stabilizing cylinder 86 attached at a proximal end thereof to the arm
14 and at a distal end thereof to a bucket stabilizing arm 88.
Returning to figure 1, the turn table component 74 is rotatably mounted on the base
component 12 so as to allow rotation of the arm 14 about an arm second pivoting axis
90. The turn table component 74 is l~lrrl~ lly coupled to a rotating means (not
shown) such as a ~. ' motor.
The base component 12 preferably takes the form of a protective shell having a door 92.
The protective shell is adapted to u-uL~u~ y enclose the electronic circuitry and part
16
~ ~18068~
of the hydraulic circuitry required for the operation of the skimming device 10. The
base member 12 includes a base mounting plate 94 for anchoring the device to a ground
surface.
In use, the bucket component 16 is put into contact with the top surface of the volume
of liquid, with the jaw members 22 in the jaw component open, '~ illustrated
in Figures 4 through 7. As the deflecting plates 38 contact the top surf~e of the volume
of liquid, their angled ~ tends to push the debris towards the peripheral edge
free segments 30.
The deflecting plates 38 are thus adapted to optimize the scooping action of the jaw
members 22 when they pivot towards their closed ..",r~ " and are also adaptecl to
prevent the bucket component 16 from being ' by material that may have a
tendency to stick to the bucket component 16 and to, other volumes of liquids
into which the bucket component 16 will eventually be later dipped into.
It should be understood that although the present invention is shown used in the contcxt
of skimming debris from a crucible containing melted aluminum, the present invention
could also be used in other contexts without departing from thc scope of the present
invention. Also, it should be understood that even in the context of aluminum containing
crucibles, the volume of liquid could be put into contact with the bucket component 16
by various means without departing from the scope of the present invention.
2~80680
For example, instead of having the bucket component raised, lowered and pivoted, the
bucket component could remain fixed while the crucible is brought in proximity with thc
bucket component 16 and then lowered or raised so that the volume of liquid contacts
bucket component 16. In other words, the present invention is not limited to a bucket
component attached to a pivotable arm but could be used without movement of the bucket
component other than the movement of the pivoting jaws without departing from thc
scope of the present invention.
In the context illustrated in Figures 1 through 9, the arm 14 is first pivoted about the arm
pivoting axis 76 so as to raise the bucket component 16. The crucible 96 containimg a
volume of melted aluminum is then brought in a proximal l~ ' ' . to the bucket
component 16 by ~ . ' conveyer belts. The arm 1~ is then pivoted about the
arm pivoting axis 76 so as to lower the bucket component 16 until it contacts the upper
surface of the volume of melted aluminum.
As iLlustrated in figure 9, one of the jaw members 22 is then pivoted relatively to the
opposed fixed jaw member 22 thus skimming debris such as the solidifying alumina bath
floating on top of the surface of melted aluminum. Rotation of the mobile jaw member
22 is indicated by arrow A in figure 9.
The jaw member base wall 24 being substantially triangular in shape, its gr~\mrtrir:~l
crnFi~r~ti~n makes it particularly well adapted to scooping the floating debris. Indecd,
18
218068~
the larger volume of liquid is skimmed by the outer peripheral portion of the base wall
24. The outer peripheral portion of the base wall 24 is adapted to receive a larger volume
of debris since the outer peripheral surface of the jaw member base wall 24 is larger than
the inner surface adjacent to the jaw member pivoting axis 28.
As illustrated in Figures 9, the pivoting jaw member 22 skims the top surface of the
volume of melted aluminum until it reaches the jaw closed, '~ Once in the
jaw closed ~,ullrO the sealing means prevent the debris from falling out of the
open top container formed by the bucket component 16.
Once the jaw members 22 are in the jaw closed rllnfigu~inn the arm 14 is pivoted
above the arm pivotal axis 76 so as to raise the bucket component 16 out of the crucible
96. as illustrated in figure 9, the turntable component 74 is then pivoted above the
second pivoting axis 90, according to arrow B so as to position the bucket component 16
over a waste discharge area or container (not shown).
The jaw members are then opened and the angled ~nnfi~ n of the jaw membcr Ibase
wall 24 allows the debris to fall out of the bucket component 16. The operation is
repeated cyclically as crucible 96 is brought into the proximity of the skimmmg device
10 by co,... ' conveyer belts.
In an alternative b. ' of the invention 10', illustrated in Figures 10 and 11, the
19
218068~
arm 14 has a telescopic c~ L.u.,Lio,. and is thus adapted to extend or retract
1~ ~ ' 'ly. The telescopic segmcnt 98 is extracted and retracted by telescopic piston
type component 100 fixed at one end to the arm 14 and at its other end to the telescopic
segment 98.
In the second .,.I.bl " 10' illustrated in Figures 10 and 11, the arm piston component
78 is assisted by an auxiliary arm piston component 102. The telescopic segment 98
allows for further adjustment of the positioning of the bucket component 16.
As illustrated more ~ ,ir~lly in fgure 11, the second ' " 10' is fur~her
provided with a heat sensing and display means for sensing and displaying the
L~ ,ldlulci of the bucket component 16. The heat sensing and display means preferably
takes the form of an infrared emittcr and receptor ~,o~llb' ' 104 linked to an electronic
circuitry and to a visual display screen 106 and optionally to an alarm system.
The display screen 106 is preferably mounted on a wall part of a protective cabin 108.
The crucible 96 is 1: ~ adjaccnt a protection ramp 108. The infrared emitter 104
is adapted to send an ifra-red beam 108 on the bucket component 16.
The heat sensing and display means is adapted to prevent the bucket component 16 fiom
being dipped into the volume of melted aluminum when the i . ~.L~; differential
between the bucket component 16 and the melted aluminum reaches a ~lc;Jc;L~
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value. The heat sensing and display means is thus adapted to prevent explosions that
could occur when the bucket component 16 have a relatively low surface ' . ~ and
the aullOullJ ..g ~ i., has a relative humidity ratio.
The heat sensing means may be optionally linked to an electronic circuitry that controls
the speed at which the arm 14 pivots so as to lower the bucket component 16 into the
melted aluminum. In the event that the bucket component 16 has a relatively low
surface l~1U~ UI~;~ the lowering of the bucket component 16 into the melted aluminum
may be slowed down so as to allow the bucket component 16 to be warmed by the hcat
convicting out of the crucible 96. The electronic circuitry may be adapted to allow the
lowering of the bucket component 16 at normal speeds when the surface I . clLule of
the bucket component 16 reaches a ~ r~ d value.
Various ."~ r;~_l;.. ., variations and adaptations may be made to the speclfic
~,l.lb " of the invention L,l. ' rOI~ described without departing from the scope
of the invention as defined in the following claims.
