Note: Descriptions are shown in the official language in which they were submitted.
CA 02240332 2001-04-27
METAL CASTING PROCESSES AND APPARATUS
Field of the invention
The invention relates to apparatus and processes for the casting of metals. In
preferred
non-limiting aspects it relates to methods and apparatus systems for automatic
casting of
metals, particularly non-ferrous metals such as lead, tin, zinc, aluminium and
alloys.
Background of the invention
A typical known system for the semi-automatic casting of zinc involves the use
of a
moving launder which is indexed to cast metal into moulds arranged around the
launder in
to semi-circular fashion. The cast metal is skimmed manually and the moulds do
not move
between the time the zinc is cast until such time as the metal is solidified.
As there is a
limit to the number of moulds which can be arranged around a launder, the rate
of casting
of metal is limited by the number of moulds which can be placed near the
launder and the
rate of cooling for metal. Most systems of this type which have a maximum
capacity of
15 15 tonnes per hour. On an industrial scale, as 15 tonnes per hour is not
high there is
considerable need for the development of approaches which lead to higher
production rates
and do not suffer to the same extent from the crowding problems associated
with
arrangement of a group of moulds in a semi-circle around a launder.
Furthermore, the individual elements of such commercially known processes such
as the
2o skimming of dross, the formation of dross during casting and the removal of
casting pins
after the cast metal has solidified all involve a range of problems which are
summarised
below.
In the case of dross formation during casting, it is well known that agitation
and exposure
to the atmosphere of molten metals and alloys tends to cause the formation of
dross and
25 scums during the pouring process largely as a result of oxidation
reactions. This
inevitably causes efficiency losses and reduced cost efficiency because the
skimmed dross
needs to be returned to the melting furnace to recover the metal value
contained therein.
In current pouring practice, the molten metal or alloy is typically poured
into a variety of
moulds, e.g. moulds for producing ingots or blocks which may range from a few
kilograms
CA 02240332 2001-04-27
to 5,000 kilograms in weight. In one approach molten metal is poured through
funnels and
down tubes located at the ends of launders thereby creating a vortex effect in
the
down tube and so drawing and trapping air in the melt with resultant oxidation
and dross
formation. Thus there is a need for development of a pouring approach which
reduces the
rate of formation of dross as a result of pouring.
With regard to skimming of dross from molten metals, in conventional practice
such
skimming is normally carried out with hand operated paddles. This is dangerous
for the
operator and it requires a significant degree of dexterity to be exercised by
any operator to
avoid any partial freezing or sticking of a paddle to a mould or ingot as the
paddle is being
drawn over the molten metal surface.
As for the removal of cast blocks from moulds and also the removal of lifting
pins cast in
with the blocks or ingots, manufacturers are typically casting blocks or
ingots in water
cooled steel moulds and removing them by inverting the moulds or "casting in"
removable
lifting tools such as tapered pins or hooks.
In the majority of the block casting plants today, cast inside hooks are used
to remove or
demould the blocks from the moulds. This is the oldest and most obvious
method.
However, it is not easy to remove cast in hooks from the sides of the block
where they are
trapped by metal shrinkage and surrounding metal flashings. These flashings
occur when
molten metal runs between the hook and the wall of the mould. To remove the
cast inside
2o hooks, an operator hammers the hooks out normally with a five kilogram
sledge hammer
requiring an average of five blows to dislodge the hooks depending on the
amount of
flashing behind the hooks. The operator then proceeds to remove all flashings
from the
cavity left by the hook using a sharp chisel with a long handle. As this
operation demands
great amounts of time and labour as well as causing unacceptable levels of
operator
injuries, there is clearly scope for the development of more efficient
techniques.
In the case of tapered lifting pins which are used instead of side hooks in
some
installations, pins which are tapered from a major diameter at the bottom to a
minor
diameter at the upper end and provided with an enlarged head are used. These
are placed
in the mould and the metal cast around the pins. Following cooling of the
metal, in some
3o semi-automated operations, the block or ingot is lifted off the mould by a
lifting grabber
which hooks on the top of the pins and transfers it to a pin press which
removes the pins
CA 02240332 2001-04-27
3
from the block by pushing the pins down through the block into a collecting
tray. After
the block is taken away, the operator manually carries the lifting pins back
to the mould
for a new pouring cycle with the consequence risk of injury as the pins are
often of heavy
construction, typically weighing 1 S to 20 kilograms each and are at high
temperature.
Thus there is a need for an alternative automated approach which does not
require the
operator to lift the pins manually.
Disclosure of the Invention
The invention provides in one aspect apparatus for the casting of metals
having a
sequential drive for indexing moulds provided thereon to a plurality of
stations, the
l0 plurality of stations including: a casting station for casting molten metal
into a mould; a
separate transfer station provided with transfer means for transferring a
mould containing
molten metal cast into the casting station to a cooling facility separate from
the sequential
drive allowing for the static cooling of the molten metal in an area remote
from the
sequential drive and return means for returning a cooled mould containing
solidified metal
ingot from the cooling facility to the sequential drive; and a delivery
station provided with
removal means for removing the solidified metal ingot from the sequential
drive leaving an
empty mould on the sequential drive for return to the casting station.
Preferably the apparatus includes a skimming station located between the
casting station
and transfer station. At the skimming station dross may be removed from the
molten
2o metal cast into the mould either manually or with automatic machinery. The
dross may
be removed with one or more paddles. The one or more paddles may include a
curved or
spoon shaped section for dross removal. They may be operated by skimming off
dross on
the surface of the metal using one or more strokes. The one or more paddles
may be
sprung or unsprung. A robot or other automatic equipment may be used to stroke
the one
or more paddles.
Suitably the return means is arranged to return cooled moulds to the
sequential drive at the
transfer station.
The sequential drive may include a driven rotating platform or carousel. The
moulds may
be placed on the platform and indexed to the different stations. The platform
may include
CA 02240332 2001-04-27
4
a plurality of cradles for receiving the moulds. Suitably there are four or
more cradles.
The sequential drive may include control means to limit the disturbances to
molten metal
cast into moulds on the drive. The control means may include an electronically
controlled
servo-motor. It may maintain the moulds at constant speed between phases of
acceleration
and deceleration. It may accelerate and/or decelerate the moulds according to
a velocity
versus time relationship which is substantially sinusoidal i.e. during
acceleration the
relationship can be expressed as sin (f(t)) where t is time over the
acceleration period
starting from a velocity of zero. This similarly applies for deceleration. The
cooling
facility is provided to allow time for cooling and solidification of the metal
in the moulds
in a still area which provides that the moulds are protected from disturbances
by
vibrations or other movements in order to facilitate high quality casting of
ingots. It is
well known that vibration of moulds during cooling is liable to create
undesirable ripples
and fins on the surface of the cast product.
The cooling facility may be any area substantially isolated from vibration or
other
disturbance. It may include cooling means to speed up the cooling of moulds at
a rate
greater than would be expected if the moulds were simply left to cool in the
air at ambient
temperature.
The cooling means may provide for the moulds to be in contact with a cooling
fluid such
as water. The cooling fluid such as water may be circulated around the moulds
by a pump
or other appropriate means. The cooling means may include a tank. There may be
a
plurality of tanks. Each tank may be of a size suitable to accommodate a
single mould or
more than one mould for cooling. Most suitably the tanks and moulds are
constructed so
that the lip provided on opposed sides of the moulds may rest upon or be
otherwise
supported by the sides of the tank. In a particularly preferred arrangement
the cooling
facility includes a plurality of tanks arranged in a straight line.
The transfer means may include an overhead crane or any other suitable pick
and place
apparatus. It may include one or more overhead rails for moving the crane from
a
location above the sequential drive. At this location it can pick up a mould
containing
molten metal. The crane is then driven along the rails to the cooling
facility. Thus the
crane may include a drive motor. Suitably it will be an electrical servo-
motor. At the
CA 02240332 2001-04-27
cooling facility the mould containing molten metal is deposited. Subsequently,
a mould
with cooled metal is picked up to be returned to the sequential drive.
The servo-motor for the crane may be operated by crane control means. The
crane
control means may accelerate and/or decelerate the moulds according to a
velocity versus
5 time relationship which is substantially sinusoidal. It may maintain the
crane at constant
speed between phases of acceleration and deceleration.
Suitably the crane includes mould gripping means which are suspended from the
crane.
The mould gripping means may be pivotally attached to the crane. The mould
gripping
means may be adapted to pivot contrary to the direction of acceleration or
deceleration
to The invention also provides a launder for casting molten metal into a
mould. The launder
may be tiltable. It may include a compressible support such as a spring loaded
support or
other equivalent e.g. a hydraulically, electrically or pneumatically actuated
support. The
launder may be associated with control means for controlling the operation of
a valve.
The level of molten metal in the tilting launder may be varied or, more
preferably
kept constant throughout the pouring process regardless of the incoming flow
rates.
Where it is desired to maintain the level of metal constant the opening of the
valve is
arranged to be proportional to the weight of the launder and hence
proportional to the flow
rate of the incoming molten metal. Therefore variations in the flow rates
through the
launder do not necessarily affect the level of the molten metal reservoir.
The level in the launder may be proportional to the loading force in the
support
mechanism. The launder is suited to both continuous and batch production.
Where the launder is used in association with the apparatus for casting metals
of the
invention it will be located at the casting station. The launder will operate
to sequentially
fill moulds indexed to the launder by a sequential drive. It may be associated
with sensing
means which sense the level of metal cast into each mould. The sensing means
may
actuate the valve to limit the amount of metal cast into each mould.
In operating casting apparatus according to the invention it is preferable to
cast each metal
ingot around pins which are used to facilitate removal of the ingot from a
mould. For this
purpose the pins may be provided with holding means which can be readily
grasped or
CA 02240332 2001-04-27
6
otherwise held by conventional equipment for pulling the ingots out of a
mould. The
holding means may include an enlarged head portion. Two such pins per ingot
are
preferred. The pins may be tapered. They may be placed in a mould prior to
casting with
the major diameter of the pin located at the bottom of the mould and the minor
diameter
at an upper portion of the pin. The enlarged head portion is provided above
the minor
diameter portion. The pins may be manually removed from cast ingots in the
conventional manner, namely with a sledge hammer. Alternatively, an automatic
mechanical device may be used to perform this function.
Of course, removal of the pins only occurs after removal from the sequential
drive by the
removal means.
The pin removal apparatus may also include pushing means. The pushing means
may
serve to push the pins from the ingot by applying force on the pins and hence
the frictional
engagement is released. The pushing means may include one or more hydraulic or
pneumatic cylinders or electric actuators. Most suitably it includes two such
cylinders.
In a further aspect the invention provides a method for the casting of metals
including the
steps o~ indexing a mould in series on a rotating carousel to a casting
station, a skimming
station, a transfer station and a delivery station; casting molten metal into
the mould at the
casting station; skimming dross from the molten metal at the skimming station;
transfernng the mould containing molten metal from the transfer station to a
cooling
2o station remote from the transfer station and replacing it at the transfer
station with a
cooled mould containing a solidified metal ingot from the cooling station;
removing the
solidified metal ingot from the cooled mould at the delivery station; and
returning the
cooled mould less solidified metal ingot to the casting station.
In a further aspect of the invention, an apparatus for the casting of metals
is provided, the
apparatus having a sequential drive for indexing moulds provided thereon to a
plurality of
stations, the plurality of stations including: a casting station for casting
molten metal into a
mould; and a separate transfer station provided with transfer means for
transfernng a
mould containing molten metal cast into the mould at the casting station to a
cooling
facility separate from the sequential drive allowing for the static cooling of
the molten
3o metal in an area remote from sequential drive.
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Preferably the cooling facility includes one or more cooling tanks.
The apparatus may further include a delivery station, the delivery station
provided with
removal means for removing a solidified metal ingot from the mould. The metal
ingot is
formed as a result of the cooling of the molten metal.
In a preferred form the delivery station is located on the sequential drive.
In a further
preferred form the sequential drive includes a rotary table for indexing the
moulds
provided thereon.
In a further aspect of the invention, an apparatus for the casting of metals
is provided, the
apparatus having a sequential drive for indexing moulds provided thereon to a
plurality of
to stations, the plurality of stations including: a casting station for
casting molten metal into a
mould; a separate transfer station provided with transfer means for
transferring a mould
containing molten metal cast into the mould at the casting station to a
cooling facility
separate from the sequential drive allowing for the static cooling of the
molten metal in an
area remote from the sequential drive and return means for returning a mould
from the
15 cooling facility to the sequential drive. Preferably the mould returning to
the sequential
drive contains a solidified metal ingot.
The apparatus may further include a delivery station provided with removal
means for
removing the solidified metal ingot from the mould. The metal ingot is formed
as a result
of the cooling of the molten metal. In a preferred form the delivery station
is located on
2o the sequential drive.
In a further aspect of the invention a method for the casting of metals is
provided, the
method including the steps of: indexing a mould in series on a rotating
carousel to a
casting station, a skimming station, a transfer station and a delivery
station; casting molten
metal into the mould at the casting station; skimming dross from the molten
metal at the
25 skimming station; transferring the mould containing molten metal from the
transfer station
to a cooling station remote from the transfer station and replacing it at the
transfer station
with a cooled mould containing a solidified metal ingot from the cooling
station; removing
the solidified metal ingot from the cooled mould at the delivery station; and
returning the
cooled mould less solidified metal ingot to the casting station.
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8
In a further aspect of the invention a method for the casting of metals is
provided, the
method including the steps of: indexing a mould in series on a sequential
drive to a casting
station, a separate transfer station and cooling station; casting molten metal
into the mould
at the casting station; transferring the mould containing molten metal from
the separate
transfer station to the cooling station remote from the separate transfer
station to allow for
the static cooling of the molten metal in an area remote from the sequential
drive.
In a further aspect of the invention a method for the casting of metals is
provided, the
method including the steps of: indexing a mould in series on a sequential
drive to a casting
station, a separate transfer station and a cooling station; casting molten
metal into the
mould at the casting station; transfernng the mould containing molten metal
from the
separate transfer station to the cooling station remote from the separate
transfer station to
allow for the static cooling of the molten metal in an area remote from the
sequential drive
and; returning the mould to the sequential drive.
Brief Description of the Drawings
Figure 1 a shows a plan view of a mould;
Figure 1b is an elevation of a mould section taken through the line x-x in
Figure la;
Figure 1 c is a side elevation of the mould of Figure 1 a sitting in a cooling
tank;
Figure 2a shows a side elevation of a launder;
Figure 2b shows a front elevation of a launder;
2o Figure 3 shows a side elevation of a launder;
Figure 4 shows a front elevation of a launder;
Figure 5 shows a plan view of a block casting machine;
Figure 6 shows a side elevation of the casting machine of Figure 5;
Figure 7 shows a front elevation of an overhead crane;
Figure 8 shows a side elevation of a conveyor and pin block removal device;
and
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9
Figure 9 shows a partial front elevational view of the device of Figure 8.
Detailed Description of the preferred Embodiments
In the following description, it should be noted that common reference
numerals appearing
throughout the drawings refer to similar elements.
Refernng to Figures la, 1b and lc, a typical mould construction 1 is shown.
The
construction shown in these drawings is one which is particularly suitable for
the casting
of zinc. However, it is to be understood that other metals and other mould
constructions
may be appropriate for the various forms of practice of this invention.
The mould 1 will generally be formed of a conventional metal material such as
steel or
cast iron having been moulded or stamped or fabricated as a single piece. It
includes a
peripheral lip portion 4 provided around the top of the four sides of the
mould, the sides
being slightly angled to the vertical to create a wedge shaped cast block
which can be
readily removed therefrom.
The floor of the mould includes a plurality of recesses 2 and raised portions
3 which serve
to allow access to fork truck tines. Where the mould is designed for casting
of a metal
such as zinc, it may typically have a capacity to handle a one tonne zinc
block.
The raised portions 3 in the mould also provide a base to rest two pins 9
which will
ultimately be used to assist in handling the cast block when the metal has
cooled.
The pins 9 include an enlarged head 8 and a tapered body 7. An annular recess
10 formed
2o between the head 8 and tapered body 7 provides anchor points for hooks used
to lift the
cast block out of the mould.
During cooling of metal in the mould 1, the mould is suspended in a cooling
tank 12 by
way of the lip 4 for sitting on the upper edge 14 of the walls of the tank.
Cooling fluid
such as water is passed through the tank and heating elements provided in the
tank lid 13
serve to control the rate of surface cooling and reduce imperfections in the
surface of
the molten block.
CA 02240332 2001-04-27
Refernng to Figure 2, there is shown a launder generally designated 20 which
includes an
elongate channel reservoir 22. This is provided at one end with a funnel 23
provided with
a downpipe 24 having an outlet 25.
The reservoir 22 is pivotally mounted on the pivot mount 26 near the end
opposite the
5 funnel. A generally centrally located lifting cylinder 27 is coupled to the
reservoir 22 via
the pivotal coupling connection 28. It should be noted that the pivotal
coupling is in the
form of a slot which permits a degree of up and down movement of the reservoir
relative
to the lifting cylinder.
A pair of support springs 29 proximate the funnel, resiliently support that
end of the
1o reservoir, the degree of compression of the springs being dependent upon
the level of
metal 41 in the reservoir.
The springs surround the support rod 30 which extend through the funnel and
above the
launder to be joined via pivot connections 32 to lever arms 31. The lever arms
31 pivot
about the central pivot 33 and are connected at the other end to the hydraulic
cylinder 38.
The hydraulic cylinder is in turn connected to the valve stem 39 terminating
in the valve
40 for closing off the opening 25.
Referring to Figures 3 and 4, the reference numerals used to identify the
various launder
elements are changed because the detail of the launder construction differs
significantly
from that shown in Figures 2a and 2b although the overall principal of
operation remains
2o essential the same.
The launder SO includes an elongate reservoir 51 terminating in a funnel 52
provided at
one end. The opposite end of the launder is mounted on the pivot mount 53 and
a
hydraulic cylinder 54 is connected to support an intermediate position along
the launder
via the pivot mount 55 provided on the bottom of the hydraulic cylinder and
the pivot
mount 56 between the cylinder and launder. Again, the pivot mount 55 includes
a slot to
allow some up and down play between the reservoir and the hydraulic cylinder.
The launder is provided with a v-shaped refractory lined channel 57 to deliver
molten
metal to the funnel 52.
CA 02240332 2001-04-27
1l
The tiltable reservoir, is constructed so that it may tilt in response to the
level and hence
weight of molten metal in the reservoir. This is to control the ball valve 71
for opening
and closing the funnel.
For this purpose the valve stem 70 which is connected to the attachment bar 67
is moved
up and down by the bar in response to the level of metal in the reservoir to
control flow
through the valued mouth of the funnel.
An attachment bar 67 is mounted on and pivots about the pivot bearing 66 with
the degree
of pivoting being limited by the dead stop 61 resting against the underneath
of the
reservoir. A pair of support wheels 62 which are adapted to rest on the lip of
a mould
to provides support to the attachment bar 67 and hence the launder.
A spring 59 is used to control the degree of pivoting of the attachment bar
about the pivot
bearing 66. A spring load adjustment 60 is provided at the upper end of the
spring, the
adjustment making it possible to increase or decrease the level of tension in
the spring and
also to allow the spring to be shifted longitudinally. A slot 65 for
complementary
longitudinal adjustment is provided for the connection at the bottom of the
spring. The
launder is also connected to the pivot bearing 66 via the launder attachment
64. The
position of the wheels can be varied along the longitudinally directed
adjustment slot 69 to
vary the height of the funnel.
The valve stem has a length adjustment 70a and terminates in a ball valve 71.
It is opened
2o and closed by the actuator 72. A heat resistant shield 73 shields the
actuator from the hot
metal in the launder and funnel portion.
Referring to Figures 5 to 9, the automatic casting machine 300 includes a
carousel 301
provided with a casting station 290, a skimming station 291, a transfer
station 292 and a
delivery station 293. A cooling area 294 is provided. This extends radially
away from
the transfer station. A pin removal station 295 having a delivery conveyor 296
and
labelling and weighing station 357 are provided in association with the
delivery station
293. An overhead crane assembly 297 connects the delivery station to the pin
removal
station.
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12
The skimming station includes an automatic skimmer 302. Generally this will be
in a
form of a robot 303 operating a skimmer plate 304. A dross removal chute 308
is provided
to dispose of dross removed by the automatic skimmer.
The transfer station 292 includes a first overhead crane assembly 315. The
crane has a
pair of pivotable crane arms 316 operable by an actuator 326 acting through
toggle arms
via the pivot 327. As can be seen from the drawing when the arms are in the
vertical
configuration they grab underneath the lip of the mould to support and carry a
mould.
However, when the toggle arms are operated in the reverse direction, the crane
arms splay
outwardly to let go of the mould.
1 o The crane is provided with wheels 318 which run along the rails 319 so
that it can move
from above the transfer station 292 to the cooling area 294 where it can pick
up and put
down moulds. The cooling area includes a series of cooling tanks 12 each
fitted with a
water cooling system 317.
The first crane lifting assembly including actuator, toggle arms and crane
arms is pivotally
mounted via the pivot 320 for reasons to become apparent. The hydraulic
cylinders 325
act to raise and lower the crane lifting assembly.
The second overhead crane assembly 297 includes hydraulic cylinders 355 for
raising and
lowering the block lifting and pin removal assembly 199 and the cast block or
ingot 200
attached thereto. The crane moves between a position above the delivery
station 293 to
one above the delivery conveyor 296. It includes wheels 352 and rails 351 for
this
purpose.
A lift assembly 356 is provided underneath the carousel at the delivery
station. The lift
assembly includes two lifters 358 which may take the form of pneumatic
cylinders. These
lifters are arranged to push through openings provided in the carousel to lift
the mould 1
clear of the carousel and cradle prior to being picked up by the lifting and
removal
assembly 199.
The carousel itself includes four mould cradles 310 for supporting the moulds
by their
circumferential lips 4. It also includes a support and drive mechanism 311 and
a weighing
assembly 312 for weighing the metal being cast into a mould as it is cast by
the launder 50.
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13
The carousel is controlled automatically and is powered by a variable speed
electronic
drive.
In a typical sequence of operations using the casting machinery shown in
Figure 5, molten
metal is poured from a fixed launder (not shown) into the tilting launder 50.
The rate of
delivery of molten metal through the funnel 52 of the tilting launder is
controlled by the
degree of tilt which is in turn dependent upon the weight of metal in the
launder, the
degree of tilt determining the amount of opening of valve 71.
When the weight of metal poured into the steel mould 1 as measured by the
weighing
assembly 312 reaches a predetermined limit, the actuator 72 automatically
closes off valve
l0 70 and the hydraulic cylinder 54 lifts the launder clear of the mould.
The carousel then rotates anti-clockwise to index the mould 1 now filled with
molten
metal to the skimming station 291. The acceleration and deceleration of the
variable
speed drive rotating the carousel is carefully controlled each time it indexes
the moulds to
a different station in order to minimise the surface wave actions induced in
the molten
metal. The carousel may also be provided with a mould cooling jacket (not
shown) at the
casting station to allow cooling to begin immediately after the initiation of
pouring in
order to minimise the elapsed cooling time and also minimise the thermal shock
to the
steel moulds.
The rate of acceleration and deceleration versus time applying as the moulds
are indexed
2o to the different stations may be in accordance with a sinusoidal velocity
versus time
relationship.
The skimming station 291 may also be provided with a mould cooling jacket (not
shown)
to further cool the mould at the station. The robot 303 of the automatic
skimmer 302
moves a skimmer plate 304 across the surface of the mould to pick up dross and
dump it
in the dross removal chute.
Following removal of dross, the mould is indexed to the transfer station 292.
At the
transfer station the overhead crane 315 through operation of the hydraulic
cylinders 325
lowers the crane arms which are held in the splayed position by the actuator
326 as they
are being lowered.
CA 02240332 2001-04-27
14
When the crane arms are in registry with the lip of the mould, the actuator
326 operating
through the pivot 327 by a toggle action moves the crane arms into gripping
registry with
the lip of a mould and the mould is subsequently lifted by actuation of the
hydraulic
cylinders 325 clear of the cradle 310.
The crane then travels along the rails 319 until it approaches an empty
cooling tank 12. It
decelerates to a stop above the empty tank and lowers the mould with molten
metal into
the tank, the acceleration and deceleration of the crane being again
controlled in
accordance with a sinusoidal velocity versus time relationship. The pivot 320
provided in
association with the assembly for holding the arms of the crane allows the
crane
holding the mould to freely sway from the vertical during the acceleration and
deceleration phases. This swaying action in association with the controlled
acceleration/
deceleration serves to reduce the amount of disturbance felt by the molten
metal in the
mould during the travel to the cooling tank and hence minimises ripples.
After the mould has been placed in the cooling tank and the crane arms are
retracted to
their uppermost position, the crane moves to a tank where the mould has had
sufficient
cooling, and after the lid 13 has been tilted aside, picks up the mould and
deposits it on
the cradle 310 of the carousel at the transfer station.
This cooled mould is then indexed to the delivery station 293 by the carousel
where it is
lifted clear of the cradle via the lift assembly 356.
2o Upon being lifted clear of the cradle, the overhead crane 350 moves the pin
removal
assembly 199 into registry with the pins 9 such that the two lifting hooks 206
attach under
the head of the pins.
The hydraulic cylinders 355 then lift the pin removal assembly via the lifting
connector
204. The retracted crane
then moves the cast block which has been lifted clear of the mould to the pin
removal
station 295 where it is placed on the delivery conveyor 296. The hydraulic
cylinders 207
push the pins free of the ingot on the conveyor and the pins are returned by
the crane
assembly 297 to be placed in the empty mould still at the delivery station
293. The empty
mould at the delivery station 293 may also be sprayed with a
CA 02240332 2001-04-27
release agent before indexing to the casting station in order to assist the
release of
subsequently cast blocks from the mould.
Following placement of the pins in the empty mould, the mould is indexed back
to the
casting station 290 for the entire cycle to be repeated. It is to be
appreciated that the steps
5 at the various stations around the carousel are carried out concurrently.
The delivery conveyor moves the de-pinned block to the weighing and labelling
station
357 and subsequently to a further location for pick up and delivery to a
customer.
While it has been convenient to describe the invention herein in relation to
particularly
preferred embodiments, it is to be appreciated that other constructions and
arrangements
10 are considered as falling within the scope of the invention. Various
modifications,
alterations, variations and/or additions to the constructions and arrangements
described
herein are also considered as falling within the scope and ambit of the
present invention.
