CA2240332C - Metal casting processes and apparatus - Google Patents
Metal casting processes and apparatus Download PDFInfo
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- CA2240332C CA2240332C CA 2240332 CA2240332A CA2240332C CA 2240332 C CA2240332 C CA 2240332C CA 2240332 CA2240332 CA 2240332 CA 2240332 A CA2240332 A CA 2240332A CA 2240332 C CA2240332 C CA 2240332C
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Abstract
Automated apparatus for the casting of metal such as zinc which includes an indexed carousel for indexing moulds through four stations. The stations are a casting station 290 where metal is cast via a launder 50, a skimming station 291 where an automatic robot controlled skimmer removes dross, a transfer station from which moulds containing molten metal are removed by an overhead crane to be placed in a cooling tank at a location substantially free of vibration and cooled moulds are returned by the crane to the transfer station and a delivery station 293 where the cast ingots 200 are removed from the moulds by another overhead crane and the empty moulds are recycled to the casting station. The ingots are lifted from the moulds at the delivery station by a mechanism which removes pins cast with the ingots and returns them to the empty mould.
Description
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 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 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 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 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 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.
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.
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 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.
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.
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.
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.
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.
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 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.
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 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 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 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 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 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.
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.
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 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.
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.
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.
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.
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.
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 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.
Claims (40)
1. Apparatus for the casting of metals, 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;
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 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.
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 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.
2. Apparatus according to claim 1 including a skimming station located intermediate the casting station and transfer station, the skimming station being provided with means for skimming dross from molten metal contained in a mould.
3. Apparatus according to claim 1 wherein the casting station includes a launder for delivering molten metal to a mould and weighing means for weighing the weight of metal delivered to the mould, the launder having valve means which is adapted to cut-off delivery of molten metal to the mould when the weighing means registers a weight of metal in the mould at or beyond a predetermined weight limit.
4. Apparatus according to claim 3 wherein the launder includes control means responsive to the weight of metal in the launder, the control means controlling the degree of opening of the valve means to control the rate of flow of metal from the launder to the mould.
5. Apparatus according to claim 3 wherein the launder includes an elongate metal reservoir terminating in a funnel provided with a discharge opening for delivery of molten metal to a mould, the discharge opening being provided with a ball valve for controlling metal flow therethrough.
6. Apparatus according to claim 1 wherein the sequential drive includes a carousel provided with cradles to hold moulds.
7. Apparatus according to claim 1 wherein the transfer means and return means include an overhead transfer crane for picking up a mould containing molten metal from the sequential drive and replacing it with a mould containing a solidified metal ingot and the cooling facility includes one or more cooling tanks located apart from the sequential drive.
8. Apparatus according to claim 7 wherein the overhead transfer crane includes crane drive means for driving the crane between the cooling facility and transfer station the crane drive means being adapted to accelerate and decelerate according to an acceleration/deceleration versus time relationship which is substantially sinusoidal, and a pick up assembly adapted to pick up and put down moulds at the transfer station and cooling facility, the pick up assembly being pivotally mounted on the crane in such a manner as to allow a mould being held by the assembly to sway in response to acceleration and deceleration of the overhead transfer crane.
9. Apparatus according to claim 1 wherein the removal means includes a delivery crane provided with a lifting assembly for lifting a solidified metal ingot clear of a mould at the delivery station and transferring it to a supply station.
10. Apparatus according to claim 9 wherein the removal means includes a lifting assembly for picking up and removing a solidified metal ingot by attachment to one or more pins provided in the mould when the molten metal for forming the solidified metal ingot is cast from the mould and delivering it to a supply station.
11. Apparatus according to claim 10 wherein the supply station includes a conveyor for the metal ingots and a weighing and marking facility for metal ingots placed on the conveyor.
12. Apparatus according to claim 2 wherein the skimming station includes a skimmer having one or more skimming paddles.
13. Apparatus according to claim 4 wherein the transfer means and return means include an overhead transfer crane for picking up a mould containing molten metal from the sequential drive and replacing it with a mould containing a solidified metal ingot and the cooling tanks are located apart from the sequential drive.
14. A method for the casting of metals including the steps of:-indexing a mould in series on a rotating carousel to a casting station, a skimming station, a separate 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;
transferring the mould containing molten metal from the transfer station to a cooling station remote from the transfer station to allow for static cooling of the molten metal in a remote area 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.
casting molten metal into the mould at the casting station;
skimming dross from the molten metal at the skimming station;
transferring the mould containing molten metal from the transfer station to a cooling station remote from the transfer station to allow for static cooling of the molten metal in a remote area 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.
15. A method according to claim 14 wherein the mould at the casting station is provided with a pair of pins around which the metal is cast, the pins are removed from the solidified metal ingot when it is removed from the mould at the delivery station, and the pins are replaced in the cooled mould at the delivery station to be returned with the cooled mould to the casting station.
16. A method according to claim 15 wherein the weight of metal cast into the mould is measured and controlled within predetermined limits at the casting station.
17. A method according to claim 14 wherein the mould containing molten metal is picked up from the transfer station, accelerated to move it from the vicinity of the transfer station and decelerated to rest above a cooling tank in which it is deposited to cool, the acceleration and deceleration being substantially in accordance with an acceleration/deceleration versus time relationship which is substantially sinusoidal.
18. Apparatus according to Claim 1 further including a launder for molten metal wherein the launder includes:-an elongate reservoir provided with an outlet for the discharge of molten metal therefrom;
valve means for controlling the discharge of molten metal through the outlet;
and control means responsive to the weight of molten metal in the launder to control the valve means and the rate of discharge of molten metal.
valve means for controlling the discharge of molten metal through the outlet;
and control means responsive to the weight of molten metal in the launder to control the valve means and the rate of discharge of molten metal.
19. Apparatus according to claim 18 wherein the valve means includes a ball valve provided at the outlet, the ball of said valve being connected by a valve stem passing through a funnel connected to the outlet to an actuator for opening and closing the ball valve.
20. Apparatus according to claim 18 wherein the launder is tiltable and the control means include a lever mechanism responsive to the degree of tilt to control the valve means.
21. Apparatus according to claim 20 wherein the valve means includes a valve element for controlling and stopping discharge of molten metal through the outlet, the valve element being connected by a valve stem passing through a funnel connected to the outlet to an actuator for opening and closing the valve means.
22. Apparatus according to claim 21 wherein the launder is pivotally mounted near an end opposite the end provided with the outlet, and a compressible support mechanism supports the launder near the outlet end, the lever mechanism being responsive to the degree of compression of the compressible support mechanism to raise or lower the valve stem whereby to control the rate of discharge of molten metal.
23. A method for the casting of metals according to claim 14 wherein the carousel is included in a sequential drive and static cooling of the molten metal occurs in a remote area from the sequential drive.
24. Apparatus for the casting of metals, 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 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.
25. Apparatus according to claim 24, wherein the cooling facility includes one or more cooling tanks.
26. Apparatus according to claim 24, and further including a delivery station, the delivery station provided with removal means for removing a solidified metal ingot from the mould.
27. Apparatus according to claim 26, wherein the delivery station is located on the sequential drive.
28. Apparatus according to claim 24, wherein the sequential drive includes a rotary table for indexing the moulds provided thereon.
29. Apparatus for the casting of metals, 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;
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 static cooling of the molten metal in an area remote from the sequential drive; and return means for returning a mould from the cooling facility to the sequential drive.
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 static cooling of the molten metal in an area remote from the sequential drive; and return means for returning a mould from the cooling facility to the sequential drive.
30. Apparatus according to claim 29, wherein the mould contains a solidified metal ingot.
31. Apparatus according to claim 29, and further including a delivery station provided with removal means for removing the solidified metal ingot from the mould.
32. Apparatus according to claim 26, wherein the delivery station is located on the sequential drive.
33. Apparatus according to Claim 24 further including a launder for molten metal wherein the launder includes:-an elongate reservoir provided with an outlet for the discharge of molten metal therefrom;
valve means for controlling the discharge of molten metal through the outlet;
and control means responsive to the weight of molten metal in the launder to control the valve means and the rate of discharge of molten metal.
valve means for controlling the discharge of molten metal through the outlet;
and control means responsive to the weight of molten metal in the launder to control the valve means and the rate of discharge of molten metal.
34. Apparatus according to claim 33 wherein the valve means includes a ball valve provided at the outlet, the ball of said valve being connected by a valve stem passing through a funnel connected to the outlet to an actuator for opening and closing the ball valve.
35. Apparatus according to claim 34 wherein the launder is tiltable and the control means include a lever mechanism responsive to the degree of tilt to control the valve means.
36. Apparatus according to claim 33 wherein the valve means includes a valve element for controlling and stopping discharge of molten metal through the outlet, the valve element being connected by a valve stem passing through a funnel connected to the outlet to an actuator for opening and closing the valve means.
37. Apparatus according to claim 36 wherein the launder is pivotally mounted near an end opposite the end provided with the outlet, and a compressible support mechanism supports the launder near the outlet end, the lever mechanism being responsive to the degree of compression of the compressible support mechanism to raise or lower the valve stem whereby to control the rate of discharge of molten metal.
38. A method for the casting of metals, 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;
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.
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.
39. A method for the casting of metals, 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;
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 and;
returning the mould to the sequential drive.
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 and;
returning the mould to the sequential drive.
40. Apparatus or method according to any one of claims 1, 14, 24, 29, 38 and 39, wherein the metal is a non-ferrous metal.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPO7311A AUPO731197A0 (en) | 1997-06-13 | 1997-06-13 | Method and apparatus for low dross casting |
| AUPO7311 | 1997-06-13 | ||
| AUPO7406A AUPO740697A0 (en) | 1997-06-18 | 1997-06-18 | Automatic casting of non-ferrous metals |
| AUPO7406 | 1997-06-18 | ||
| AUPO7694 | 1997-07-04 | ||
| AUPO7694A AUPO769497A0 (en) | 1997-07-04 | 1997-07-04 | Automatic skimming device |
| AUPP1429 | 1998-01-21 | ||
| AUPP1429A AUPP142998A0 (en) | 1998-01-21 | 1998-01-21 | Cast block removal system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2240332A1 CA2240332A1 (en) | 1998-12-13 |
| CA2240332C true CA2240332C (en) | 2003-08-12 |
Family
ID=27424441
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2240332 Expired - Lifetime CA2240332C (en) | 1997-06-13 | 1998-06-11 | Metal casting processes and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2240332C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI110851B (en) * | 2000-09-29 | 2003-04-15 | Outokumpu Oy | Method and apparatus for casting metal |
| CA2427894C (en) | 2003-05-05 | 2010-08-17 | Outokumpu, Oyj | Aluminium ingot casting machine |
| NO341337B1 (en) * | 2015-07-03 | 2017-10-16 | Norsk Hydro As | Equipment for continuous or semi-continuous casting of metal with improved metal filling arrangement |
| CN114798608A (en) * | 2022-05-05 | 2022-07-29 | 江西万泰铝业有限公司 | Aluminum ingot vibration cleaning device |
-
1998
- 1998-06-11 CA CA 2240332 patent/CA2240332C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2240332A1 (en) | 1998-12-13 |
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| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20180611 |