CA1268313A - Atomisation of metals - Google Patents
Atomisation of metalsInfo
- Publication number
- CA1268313A CA1268313A CA000522809A CA522809A CA1268313A CA 1268313 A CA1268313 A CA 1268313A CA 000522809 A CA000522809 A CA 000522809A CA 522809 A CA522809 A CA 522809A CA 1268313 A CA1268313 A CA 1268313A
- Authority
- CA
- Canada
- Prior art keywords
- atomising
- stream
- spray
- gas
- plenum chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 23
- 239000002184 metal Substances 0.000 title claims abstract description 23
- 238000000889 atomisation Methods 0.000 title description 8
- 150000002739 metals Chemical class 0.000 title description 2
- 239000007921 spray Substances 0.000 claims abstract description 45
- 239000007788 liquid Substances 0.000 claims abstract description 12
- 230000008021 deposition Effects 0.000 claims abstract description 10
- 229910001092 metal group alloy Inorganic materials 0.000 claims abstract description 9
- 238000009689 gas atomisation Methods 0.000 claims abstract description 7
- 230000010355 oscillation Effects 0.000 claims description 15
- 238000009826 distribution Methods 0.000 claims description 3
- 230000003534 oscillatory effect Effects 0.000 claims description 3
- 239000002245 particle Substances 0.000 abstract description 5
- 239000007789 gas Substances 0.000 description 24
- 238000000034 method Methods 0.000 description 8
- 239000000758 substrate Substances 0.000 description 7
- 238000000151 deposition Methods 0.000 description 6
- 229910001338 liquidmetal Inorganic materials 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- YSGQGNQWBLYHPE-CFUSNLFHSA-N (7r,8r,9s,10r,13s,14s,17s)-17-hydroxy-7,13-dimethyl-2,6,7,8,9,10,11,12,14,15,16,17-dodecahydro-1h-cyclopenta[a]phenanthren-3-one Chemical compound C1C[C@]2(C)[C@@H](O)CC[C@H]2[C@@H]2[C@H](C)CC3=CC(=O)CC[C@@H]3[C@H]21 YSGQGNQWBLYHPE-CFUSNLFHSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000013528 metallic particle Substances 0.000 description 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000009974 thixotropic effect Effects 0.000 description 1
Landscapes
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Abstract
ABSTRACT
A device for gas atomising a liquid stream, such as a stream of molten metal or metal alloy, has an atomising device including, for example, an annular opening for receiving the stream, The atomising device is arranged for applying atomising gas to the stream so as to form a spray of atomised particles. At least a part of the atomising gas, and preferably all, is applied by means movable relative to the stream whereby movement is imparted to the spray. This movement leads to improved uniformity or control of deposition.
A device for gas atomising a liquid stream, such as a stream of molten metal or metal alloy, has an atomising device including, for example, an annular opening for receiving the stream, The atomising device is arranged for applying atomising gas to the stream so as to form a spray of atomised particles. At least a part of the atomising gas, and preferably all, is applied by means movable relative to the stream whereby movement is imparted to the spray. This movement leads to improved uniformity or control of deposition.
Description
' ~ ~26~
ATOMISATION OF METALS
This invention relates 'co A device for gas atomising a liquid stream, such as a stream of molten metal or metal alloy.
The atomising and spray depositing of a strea~ of liquid metal has been known for many years, for example from British Patent Specification No: 1262471, and our own British Patent Specification Nos: 1379261 and 1472939. However, it has always been a problem to achieve precise control of the mass deposition in the metal on the deposition surface.
One proposal to improve the control of the mass distrlbutlon of the deposited layer of gas atomlsed of metal is set out in British Patent Specification No:
1455862 where it is proposed to oscillate the spray of atomised particles by the use of a primary set of gas jets for atomisation and two sets of secondary jets ~which are rapidly switched on and off to impart an ` oscillatory motion to the spray of atomised metal.
However, it was found that the arrangement did not give ideal control of the mass distribution of the metal deposited. Therefore, an alternative proposal ior lmparting a direction to a spray was suggested as diclosed in European Patent Publicatior ~'o: 0127303~.
That arrangement involves the switching on and off of individual gas Jets which accomplish the function of J' ,~
.`f~
': ' . ' - :~' : : :
:` ',,: ` ' '
ATOMISATION OF METALS
This invention relates 'co A device for gas atomising a liquid stream, such as a stream of molten metal or metal alloy.
The atomising and spray depositing of a strea~ of liquid metal has been known for many years, for example from British Patent Specification No: 1262471, and our own British Patent Specification Nos: 1379261 and 1472939. However, it has always been a problem to achieve precise control of the mass deposition in the metal on the deposition surface.
One proposal to improve the control of the mass distrlbutlon of the deposited layer of gas atomlsed of metal is set out in British Patent Specification No:
1455862 where it is proposed to oscillate the spray of atomised particles by the use of a primary set of gas jets for atomisation and two sets of secondary jets ~which are rapidly switched on and off to impart an ` oscillatory motion to the spray of atomised metal.
However, it was found that the arrangement did not give ideal control of the mass distribution of the metal deposited. Therefore, an alternative proposal ior lmparting a direction to a spray was suggested as diclosed in European Patent Publicatior ~'o: 0127303~.
That arrangement involves the switching on and off of individual gas Jets which accomplish the function of J' ,~
.`f~
': ' . ' - :~' : : :
:` ',,: ` ' '
- 2 - ~2~
both atomising and oscillating the spray. However, both these methods are very difficult to control, and in particular lack flexibility in operation.
In the first proposal the use of secondary jets can result in excess cooling of the deposited metal meaning that subsequently arriving particles do not coalesce properly with ehe already deposlted metal. In the second method the shapeand properties (eg temperature) of the spray can change as individual jets are switched on and off which makes it extremely difficult to ensure uniform deposition and solidification condition6.
An object of the present invention i8 to provide an improved device for g=s atomizlng a liquid stream, such as a stream of molten metal or metal alloy and for imparting controlled snd precise movements to the atomised liquid stream.
According to the present invention a device for gas atomising a liquid stream such as a stream of molten metal or molten metal alloy, comprises an atomising device~which, in use, is arranged to receive the stream aDd for directing atomising gas at the stream to form a spray of atomised particles wherein at least a part of the atomizing gas is supplied by means movable relative to the stream to impart movement to the spray.
Preferably, the atomising device and tlle atomising gas means are movable together relative to the stream.
, . : . ~ -. . : , ,
both atomising and oscillating the spray. However, both these methods are very difficult to control, and in particular lack flexibility in operation.
In the first proposal the use of secondary jets can result in excess cooling of the deposited metal meaning that subsequently arriving particles do not coalesce properly with ehe already deposlted metal. In the second method the shapeand properties (eg temperature) of the spray can change as individual jets are switched on and off which makes it extremely difficult to ensure uniform deposition and solidification condition6.
An object of the present invention i8 to provide an improved device for g=s atomizlng a liquid stream, such as a stream of molten metal or metal alloy and for imparting controlled snd precise movements to the atomised liquid stream.
According to the present invention a device for gas atomising a liquid stream such as a stream of molten metal or molten metal alloy, comprises an atomising device~which, in use, is arranged to receive the stream aDd for directing atomising gas at the stream to form a spray of atomised particles wherein at least a part of the atomizing gas is supplied by means movable relative to the stream to impart movement to the spray.
Preferably, the atomising device and tlle atomising gas means are movable together relative to the stream.
, . : . ~ -. . : , ,
- 3 - 126~3 The inventlon also includes a method of movlng a spray comprlslng positloning an atomising devlce for receiving a llquid stream such as a stream of molten metal or metal alloy, passing the liquid stream through the atomlsing device, atomising the stream by the application of atomisation gas from atomising gas means at the atomising device to form a spray of atom~sed particles, and movlng at least a part of the atomising gas means reLative to the stream durlng atomisation to impart movement to the spray.
The improved method of the present invention does not involve the switching on and off of gas jets to oscillate the spray. Instead, despite the proximity to the nozzle from which molten metal issues, we have devi~ed a system whereby the spray is moved by moving the atomising jets themselves or the whole atomising dev:ice. This has the following particular advantages over previous method:-(a) on average the atomising conditions can be ~kept relatively constant because gas jets are not being switched on and off, i.e. the ~atomising conditions may be the same or otherwise controlled regardless of the degree of movement of the spray;
(b~ the movement imparted is preferably an osclllation and the angle of oscillation can . ::. : : .
The improved method of the present invention does not involve the switching on and off of gas jets to oscillate the spray. Instead, despite the proximity to the nozzle from which molten metal issues, we have devi~ed a system whereby the spray is moved by moving the atomising jets themselves or the whole atomising dev:ice. This has the following particular advantages over previous method:-(a) on average the atomising conditions can be ~kept relatively constant because gas jets are not being switched on and off, i.e. the ~atomising conditions may be the same or otherwise controlled regardless of the degree of movement of the spray;
(b~ the movement imparted is preferably an osclllation and the angle of oscillation can . ::. : : .
- 4 ~26~ 3 be changed very easily merely by lncreasi.ng the angle of tilt of the whole or part of the atomiser during each cycle;
(c) the rate of oscillation can be easily varied; and ~d) the speed of oscillaton at any instant during each cycle of oscillation can be easily varied.
Consequently, the apparatus and method of the present invention provides a very high degree of control over the stomising device and the ~ovement of the spray which previously has not been attainable. This enables the oscillatlon conditions to be varied to suit the shape of deposit being produced or to control the deposition conditions and/or the profile of the spray on the surface of the collector.
.: In one form of the method of the invention the :
liquld strea~ is molten metal or metal alloy, the spray is directed at a ~ubstrate moving continuously through :
the spray and the spray is moved transverse to the direction of move~ent to achieve uniformity of thickness of deposition across the width of the substrate ~hereby strip, coated strip, plate or coated plate produc~s may be for:ed.
The invention will now be described by way of e~ample with refe~rence to the accompanying drawings in which:
:.
- -~Z6~3~a3 Figure 1 ifi a perspectlve dlagrammaelc vlew of a preferred apparatus;
Figure 2 illustrates diagrammatically the mode of movement of the atomising device and hence the movement imparted to a spray;
Figure 3 is a plan and side elevation of a préferred atomiser;
Figure 4 i5 sectional side elevation of the atomiser;
Figure 5 is a diagrammatic perspective view of the invent~on as applied to the manufacture of strip;
- Figure 6 is a diagrammat1c perspective view of the invention as applied ~o the coating of strip; and Figure 7 is a diagrammatic view of an alternative atomising device where only part of the device is :~ ~movable.
- In Figure 1 of the drawings a liquid strea~ 1, such as molten metal or metal alloy, is teemed through an : :atomisin~ device 2. The device 2 is generally annular : in shape and is supported by diametrically projecting supports 3. The supports 3 also serve to supply atomising gas to the atomising device in order to atomise the stream 1 into a spray 4. In order to impart : movemen~ to the spray 4 the projecting supports 3 are mounted in bearings (not shown in Figure 1) so that the whole atomising device 2 is able to tilt about the axis defined by the pro~ecting supports 3. The control of .~ .;
', 1 , , : ' : . .
' ' ; ~ "; ~ ~ :
~26E~3~3 _ 6 the tilting of the atomislng devlce 2 comprises an eccentric cam 5 and a cam follower 6 connected to one of the supports 3 as will be explained. By altering the speed of rotation of the cam 5 the rate of oscillation of the atomising device 2 can be varied. In addition, by changing the surface profile of the cam 5, the speed of oscillation at any instant durin~ the cycle of oscillation can be varied. The oscillation typically can be up to 30 from the stream ax1s although the movement may not necessarily be centered on the stream axis 9 this will depend upon the shape of the deposit being formed.
From Figure 2 it can be seen that the atomising device 2 comprises a plenum chamber 7 and a plurality of gas atomising means consisting of nozzles 8. In the preferred embodiment the whole atomising device 2 is ti.~table as indicated by Figure 2 so that,~as it ls tilted the gas issuing from the nozzles 8 imparts lateral movement ~o the spray.
Figures 3 and 4 illustrate ~ preferred embodiment of the invention ln more detail. In those Figures an atomising device 10 is positioned within an atomiser housing 11 and below the nozzle opening 12 of tundish 13. The atomising device 10 includes a plenum chamber 14 and has atomising gas jet oper.ings 15. The atomising device 10 is substantially annular in shape having a central opening 16 through which a stream 17 ~rom the ~' `:
: ' ~", ,:: - ,`' ; , .:
. ~
~268~13 tundish 13 is arranged to pass. The atomising devlce is supported within the housing 11 by diametrically opposed supports 18, 19 which project outwardly from the atomising device 10 and is posltioned sufficiently away fro~the bottom of the tundish 13 and has a central opening 16 dimensioned 60 that the atomising device may be made to undergo a tilting motio~. So that thifi tilting motion may be achieved the supports 18, 19 are mounted within respective bearings 20, 21 in the atomiser housing 11. One of the supports 18, also serves as a conduit 22 to supply atomising gas to the plenum chamber 14.
The movement of the atomising device 10 is effected by mechanical means consisting of a drum cam 23 rotated by drive means (not shown) and, a cam follower 24 pivoted at 25 and held against the cam profile by means of.-a pneumatic cylinder 26. The cam ~ollower 24 has a connecting arm 27 pivoted to it~at 28 and the arm 27 extends to a further pivotal connection 29 on a plate 30. The plate 30 is freely movable and is fixed to the support 19, as clearly shown in Figure 4, at a p~sition offset from the pivotal connection 29.
Accordingly, it will be unders~ood that movement of the drum cam 23 is translated into movement of the atomising device 10 via the cam follower 24, connecting arm 27 and plate 30. The cam profile may be designed to define a predetermined degree of movement and the speed .,~, ' ' '- '', , ~, :
_ 8 ~ ~Z68~3 of rotatlon of the drum cam, which may be readlly controlled in a known manner by an electric motor, the speed of movement of ~he atomislng device. MovemeDt of the atomising device, suitably a to and fro oscillatory movement, imparts a corresponding movement to the spray since the atomising device 10 carrles with it the atomising ga3 jet openings 15.
The atomising device of the present invention is particularly useful for producing strip or plate 31 as illustra~ed in Figure 5. Also, the apparatus may be used for producing spray coated strip or plate products 32 as shown in Figure 6. ln producing these products the spray is moved to and fro at right angles to the direction of movement of a collector 33 movlng continuously through the spray as indicated by the arrows in the Figures. This ensure that the deposit 34 is. for=ed unifor=ly across the width of the collector, or substrate, preferably in the thickness range 0.5mm -50=m. PreEerably the substrate or collector will pass a plurality of atomising devices aligned along the axis of the ~ovement of the substrate. In respect of coated strip or plate 31 the substrate to be coated may suitably be unwound from a decoiler 35 diagrammatically illustrated in Figure 6. Although the present invention is particularly suitable for forming strip, plate and coated strip and plate it will be understood, that the atomiser can be used beneficially for producing many ~'~
,. . ~: :
::
g - ~Z~ 3 other products including ingotfi, bars, tubes, rings, rolls, conical shapes forging and extrufiion blanks, spray coated products, laminates, composites, and products for thixotropic deformation etc. The substrate or collector may be ~n flat substrate, an endless belt or a rotatable mandrel.
The formation of s~rip will now be described by way of example:
EXAMPLE OF S~RIP PRODUCTION: WI~TH = 300mm DEPOSITED MATERIAL - 0.15% CARBON STEEL
POURING TEMP. - 1580 degrees centigrade METAL POURlNG NOZZLE - 9.Omm bore SPRAY HEIGHT - 630mm (ie Distance from the underside of the ~ atomiser to collector) ; OSCILLATING SPEED - 10 cycles/sec OSCILLATING ANGLE - 13 about a vertical axis ATOMISING GAS - Nitrogen COLLECTOR - O.Smm thick X 300mm wide X
1000mm length mild sceel plate - grit blasted.
COLLECTOR MOVEME~T - 40mm/sec LIQUID METAL FLOW
RATE INTO ATOMISEK - 58~g/~in GAS/METAL RATIO _ 0.3 Kg/Kg DEPOSlT THICKNESS - 8mm , , , - .: -:' .'. -, .
10 - ~L26831;~
STRIP PRODUCTION: WIDTH - 155~m DEP~SlTED METAL - 0.15% CARBON STEEL
PO~RING TEMP. ~ 570 Centigrade ~ETAL POURING NOZZLE ~ 9.0mm bore SPRAY HEIGHT - 630mm OSCILLATING ANGLE - +/-7 degrees about a vertical axis OSCILLATING SPEED - 10 cycles/sec ATOMISING GAS - Nitrogen COLLECTOR - 0.5mm x 155mm wide x lOOOmm length mild steel plate COLLECTOR MOV~MENT - 60mm/sec LIQUID METAL FLOW RATE
INTO ATOMISER - 60kg/min GAS/METAL RATIO - 0.35 Kg/Kg DEPOSIT THICKNESS - lOmm ~ ~ In the present invention the spray cone generated ; by the atomis1ng devlce is always maintained and the gas je~s which, in prior inventions, were used to impart an oscilation to the spray, are used merely for atomisation.
Not all the jets need Decessarily be moved~ For e~ample in Figure 7 an atomising device 40 is substantially square shaped in plan and comprises pairs OI opposed atomising ~ets 41, 42. Atomising jets 41 are ~ovable so as to move a spray, formed by passing a ' ~:
. . :: . ":, : , .
- : ,: , :. . : . ..
lZ6F~
llquid stream through the centre of the device 40, in a to and fro direction indcated by arrow 43. However, opposed jets 42 are flxed to provide side curtains of gas which keep the oscillating spray within confined lateral limits. As an alternative the atomising gas means may simply be a single gas opening such as an annulus.
Whilst the invention has been particularly descrlbed with reference to the atomisation of liquid metal streams, the invention may be applicable ~o the atomisation of other liquid streams such as liquid ceramics or liquid stream or spray into which solid metallic or non-metallic particles or f$bres are injected or incorporated. Also, whllst the present -lnvention has been described with reference to mechanical control means, preferred methods for controlling the movement of the atomiser may be electro-:: :
~echanical means such as a programme controlled steppermotor, or hydraulic means such as a programme controlled electro-hydraulic servo mechanism using a linear actuator to control oscillation movement.
The abo~e devices can also be used for producing gas atomised metal powders whereby the movement of the spray can impart improved cooling to the atomised partlcles.
.~ .
:
" . .
. :, . .
.
(c) the rate of oscillation can be easily varied; and ~d) the speed of oscillaton at any instant during each cycle of oscillation can be easily varied.
Consequently, the apparatus and method of the present invention provides a very high degree of control over the stomising device and the ~ovement of the spray which previously has not been attainable. This enables the oscillatlon conditions to be varied to suit the shape of deposit being produced or to control the deposition conditions and/or the profile of the spray on the surface of the collector.
.: In one form of the method of the invention the :
liquld strea~ is molten metal or metal alloy, the spray is directed at a ~ubstrate moving continuously through :
the spray and the spray is moved transverse to the direction of move~ent to achieve uniformity of thickness of deposition across the width of the substrate ~hereby strip, coated strip, plate or coated plate produc~s may be for:ed.
The invention will now be described by way of e~ample with refe~rence to the accompanying drawings in which:
:.
- -~Z6~3~a3 Figure 1 ifi a perspectlve dlagrammaelc vlew of a preferred apparatus;
Figure 2 illustrates diagrammatically the mode of movement of the atomising device and hence the movement imparted to a spray;
Figure 3 is a plan and side elevation of a préferred atomiser;
Figure 4 i5 sectional side elevation of the atomiser;
Figure 5 is a diagrammatic perspective view of the invent~on as applied to the manufacture of strip;
- Figure 6 is a diagrammat1c perspective view of the invention as applied ~o the coating of strip; and Figure 7 is a diagrammatic view of an alternative atomising device where only part of the device is :~ ~movable.
- In Figure 1 of the drawings a liquid strea~ 1, such as molten metal or metal alloy, is teemed through an : :atomisin~ device 2. The device 2 is generally annular : in shape and is supported by diametrically projecting supports 3. The supports 3 also serve to supply atomising gas to the atomising device in order to atomise the stream 1 into a spray 4. In order to impart : movemen~ to the spray 4 the projecting supports 3 are mounted in bearings (not shown in Figure 1) so that the whole atomising device 2 is able to tilt about the axis defined by the pro~ecting supports 3. The control of .~ .;
', 1 , , : ' : . .
' ' ; ~ "; ~ ~ :
~26E~3~3 _ 6 the tilting of the atomislng devlce 2 comprises an eccentric cam 5 and a cam follower 6 connected to one of the supports 3 as will be explained. By altering the speed of rotation of the cam 5 the rate of oscillation of the atomising device 2 can be varied. In addition, by changing the surface profile of the cam 5, the speed of oscillation at any instant durin~ the cycle of oscillation can be varied. The oscillation typically can be up to 30 from the stream ax1s although the movement may not necessarily be centered on the stream axis 9 this will depend upon the shape of the deposit being formed.
From Figure 2 it can be seen that the atomising device 2 comprises a plenum chamber 7 and a plurality of gas atomising means consisting of nozzles 8. In the preferred embodiment the whole atomising device 2 is ti.~table as indicated by Figure 2 so that,~as it ls tilted the gas issuing from the nozzles 8 imparts lateral movement ~o the spray.
Figures 3 and 4 illustrate ~ preferred embodiment of the invention ln more detail. In those Figures an atomising device 10 is positioned within an atomiser housing 11 and below the nozzle opening 12 of tundish 13. The atomising device 10 includes a plenum chamber 14 and has atomising gas jet oper.ings 15. The atomising device 10 is substantially annular in shape having a central opening 16 through which a stream 17 ~rom the ~' `:
: ' ~", ,:: - ,`' ; , .:
. ~
~268~13 tundish 13 is arranged to pass. The atomising devlce is supported within the housing 11 by diametrically opposed supports 18, 19 which project outwardly from the atomising device 10 and is posltioned sufficiently away fro~the bottom of the tundish 13 and has a central opening 16 dimensioned 60 that the atomising device may be made to undergo a tilting motio~. So that thifi tilting motion may be achieved the supports 18, 19 are mounted within respective bearings 20, 21 in the atomiser housing 11. One of the supports 18, also serves as a conduit 22 to supply atomising gas to the plenum chamber 14.
The movement of the atomising device 10 is effected by mechanical means consisting of a drum cam 23 rotated by drive means (not shown) and, a cam follower 24 pivoted at 25 and held against the cam profile by means of.-a pneumatic cylinder 26. The cam ~ollower 24 has a connecting arm 27 pivoted to it~at 28 and the arm 27 extends to a further pivotal connection 29 on a plate 30. The plate 30 is freely movable and is fixed to the support 19, as clearly shown in Figure 4, at a p~sition offset from the pivotal connection 29.
Accordingly, it will be unders~ood that movement of the drum cam 23 is translated into movement of the atomising device 10 via the cam follower 24, connecting arm 27 and plate 30. The cam profile may be designed to define a predetermined degree of movement and the speed .,~, ' ' '- '', , ~, :
_ 8 ~ ~Z68~3 of rotatlon of the drum cam, which may be readlly controlled in a known manner by an electric motor, the speed of movement of ~he atomislng device. MovemeDt of the atomising device, suitably a to and fro oscillatory movement, imparts a corresponding movement to the spray since the atomising device 10 carrles with it the atomising ga3 jet openings 15.
The atomising device of the present invention is particularly useful for producing strip or plate 31 as illustra~ed in Figure 5. Also, the apparatus may be used for producing spray coated strip or plate products 32 as shown in Figure 6. ln producing these products the spray is moved to and fro at right angles to the direction of movement of a collector 33 movlng continuously through the spray as indicated by the arrows in the Figures. This ensure that the deposit 34 is. for=ed unifor=ly across the width of the collector, or substrate, preferably in the thickness range 0.5mm -50=m. PreEerably the substrate or collector will pass a plurality of atomising devices aligned along the axis of the ~ovement of the substrate. In respect of coated strip or plate 31 the substrate to be coated may suitably be unwound from a decoiler 35 diagrammatically illustrated in Figure 6. Although the present invention is particularly suitable for forming strip, plate and coated strip and plate it will be understood, that the atomiser can be used beneficially for producing many ~'~
,. . ~: :
::
g - ~Z~ 3 other products including ingotfi, bars, tubes, rings, rolls, conical shapes forging and extrufiion blanks, spray coated products, laminates, composites, and products for thixotropic deformation etc. The substrate or collector may be ~n flat substrate, an endless belt or a rotatable mandrel.
The formation of s~rip will now be described by way of example:
EXAMPLE OF S~RIP PRODUCTION: WI~TH = 300mm DEPOSITED MATERIAL - 0.15% CARBON STEEL
POURING TEMP. - 1580 degrees centigrade METAL POURlNG NOZZLE - 9.Omm bore SPRAY HEIGHT - 630mm (ie Distance from the underside of the ~ atomiser to collector) ; OSCILLATING SPEED - 10 cycles/sec OSCILLATING ANGLE - 13 about a vertical axis ATOMISING GAS - Nitrogen COLLECTOR - O.Smm thick X 300mm wide X
1000mm length mild sceel plate - grit blasted.
COLLECTOR MOVEME~T - 40mm/sec LIQUID METAL FLOW
RATE INTO ATOMISEK - 58~g/~in GAS/METAL RATIO _ 0.3 Kg/Kg DEPOSlT THICKNESS - 8mm , , , - .: -:' .'. -, .
10 - ~L26831;~
STRIP PRODUCTION: WIDTH - 155~m DEP~SlTED METAL - 0.15% CARBON STEEL
PO~RING TEMP. ~ 570 Centigrade ~ETAL POURING NOZZLE ~ 9.0mm bore SPRAY HEIGHT - 630mm OSCILLATING ANGLE - +/-7 degrees about a vertical axis OSCILLATING SPEED - 10 cycles/sec ATOMISING GAS - Nitrogen COLLECTOR - 0.5mm x 155mm wide x lOOOmm length mild steel plate COLLECTOR MOV~MENT - 60mm/sec LIQUID METAL FLOW RATE
INTO ATOMISER - 60kg/min GAS/METAL RATIO - 0.35 Kg/Kg DEPOSIT THICKNESS - lOmm ~ ~ In the present invention the spray cone generated ; by the atomis1ng devlce is always maintained and the gas je~s which, in prior inventions, were used to impart an oscilation to the spray, are used merely for atomisation.
Not all the jets need Decessarily be moved~ For e~ample in Figure 7 an atomising device 40 is substantially square shaped in plan and comprises pairs OI opposed atomising ~ets 41, 42. Atomising jets 41 are ~ovable so as to move a spray, formed by passing a ' ~:
. . :: . ":, : , .
- : ,: , :. . : . ..
lZ6F~
llquid stream through the centre of the device 40, in a to and fro direction indcated by arrow 43. However, opposed jets 42 are flxed to provide side curtains of gas which keep the oscillating spray within confined lateral limits. As an alternative the atomising gas means may simply be a single gas opening such as an annulus.
Whilst the invention has been particularly descrlbed with reference to the atomisation of liquid metal streams, the invention may be applicable ~o the atomisation of other liquid streams such as liquid ceramics or liquid stream or spray into which solid metallic or non-metallic particles or f$bres are injected or incorporated. Also, whllst the present -lnvention has been described with reference to mechanical control means, preferred methods for controlling the movement of the atomiser may be electro-:: :
~echanical means such as a programme controlled steppermotor, or hydraulic means such as a programme controlled electro-hydraulic servo mechanism using a linear actuator to control oscillation movement.
The abo~e devices can also be used for producing gas atomised metal powders whereby the movement of the spray can impart improved cooling to the atomised partlcles.
.~ .
:
" . .
. :, . .
.
Claims (15)
1. Apparatus for gas atomising a liquid stream, such as a stream of molten metal or metal alloy, and for controlling the mass distribution of a layer deposition from the atomised stream, the combination comprising:
an atomising device;
a plenum chamber forming a part of the atomising device and defining an opening through which the stream may be teemed;
atomising means communicating with the plenum chamber for forming an atomising gas flow field of predetermined geometry which atomises the stream into a spray of droplets; and means for moving the atomising device angularly about an axis and relative to the stream whereby the application of angular movement about said axis may impart an oscillation to the gas flow field and thereby to the spray with the geometry of the atomising gas flow field remaining substantially constant.
an atomising device;
a plenum chamber forming a part of the atomising device and defining an opening through which the stream may be teemed;
atomising means communicating with the plenum chamber for forming an atomising gas flow field of predetermined geometry which atomises the stream into a spray of droplets; and means for moving the atomising device angularly about an axis and relative to the stream whereby the application of angular movement about said axis may impart an oscillation to the gas flow field and thereby to the spray with the geometry of the atomising gas flow field remaining substantially constant.
2. Apparatus according to claim 1 wherein the atomising device is annular and the atomising means comprises a plurality of atomising jets.
3. Apparatus according to claim 1 wherein the atomising device is annular and the atomising means comprises an annulus.
4. Apparatus according to claim 2, further comprising means for supporting the atomising device at diametrically opposed positions, the support means communicating with the plenum chamber with an atomising gas supply.
5. Apparatus according to claim 1, further comprising control means for controlling the moving means so as to move the atomising device through a predetermined cycle of movements.
6. Apparatus according to claim 5 wherein the control means comprises a movable cam and a cam follower connected to the atomising device and adapted follow the movable cam.
7. Apparatus according to claim 5 wherein the control means comprises an electro-mechanical means including a stepper motor.
8. Apparatus according to claim 5 wherein the control means comprises hydraulic means including an electro-hydraulic servo mechanism.
9. Apparatus for gas atomising a stream and for controlling the deposition conditions of a deposit formed from deposition of the atomised stream, the combination comprising:
an annular atomising device;
an annular plenum chamber formed within the atomising device and having a central opening through which the stream may pass;
means coupled to the atomising device for supporting the atomising device including an inlet path communicating the plenum chamber with an atomising gas source;
a plurality of atomising gas jet openings formed in the plenum chamber for directing atomising gas onto the stream passing through the opening, the atomising gas jet openings being positioned in a predetermined fixed relationship relative to one another so as to form an atomising gas flow field of predetermined geometry; and means for moving the support means and the atomising device angularly about an axis passing through the support means whereby the angular movement about the axis imparts an oscillation to the gas flow field and to the spray with the geometry of the atomising gas flow field remaining substantially constant and whereby the shape and deposition conditions of a formed deposit are controlled.
an annular atomising device;
an annular plenum chamber formed within the atomising device and having a central opening through which the stream may pass;
means coupled to the atomising device for supporting the atomising device including an inlet path communicating the plenum chamber with an atomising gas source;
a plurality of atomising gas jet openings formed in the plenum chamber for directing atomising gas onto the stream passing through the opening, the atomising gas jet openings being positioned in a predetermined fixed relationship relative to one another so as to form an atomising gas flow field of predetermined geometry; and means for moving the support means and the atomising device angularly about an axis passing through the support means whereby the angular movement about the axis imparts an oscillation to the gas flow field and to the spray with the geometry of the atomising gas flow field remaining substantially constant and whereby the shape and deposition conditions of a formed deposit are controlled.
10. Apparatus for controlling the mass distribution of a layer deposited on a surface by an atomised stream, the combination comprising:
a device for forming an atomising gas flow field of predetermined geometry which atomises the stream into a spray of droplets comprising a plenum chamber defining an opening through which the stream is teemed and atomising means including a nozzle in said plenum chamber for directing atomising gas toward the stream;
and means for oscillating said plenum chamber about said stream whereby said nozzle oscillates about said stream and the atomising gas directed through said outlet causes the stream to oscillate.
a device for forming an atomising gas flow field of predetermined geometry which atomises the stream into a spray of droplets comprising a plenum chamber defining an opening through which the stream is teemed and atomising means including a nozzle in said plenum chamber for directing atomising gas toward the stream;
and means for oscillating said plenum chamber about said stream whereby said nozzle oscillates about said stream and the atomising gas directed through said outlet causes the stream to oscillate.
11. Apparatus for gas atomizing a liquid stream such as stream of molten metal or metal alloy, comprising;
an atomizing device;
a plenum chamber forming a part of the atomizing device and defining an opening through which the stream may be teemed;
atomizing means communicating with the plenum chamber for atomizing the stream into a spray of droplets;
means for moving the atomizing device relative to the stream whereby the application of said movement may impart movement to the spray; and control means for imparting oscillatory movement to the spray of droplets, said control means including first means for varying the rate of said oscillations and second means for varying the speed of oscillation during each cycle of oscillation.
an atomizing device;
a plenum chamber forming a part of the atomizing device and defining an opening through which the stream may be teemed;
atomizing means communicating with the plenum chamber for atomizing the stream into a spray of droplets;
means for moving the atomizing device relative to the stream whereby the application of said movement may impart movement to the spray; and control means for imparting oscillatory movement to the spray of droplets, said control means including first means for varying the rate of said oscillations and second means for varying the speed of oscillation during each cycle of oscillation.
12. Apparatus according to Claim 11 wherein the control means includes third means for determining the amplitude of oscillation.
13. Apparatus according to Claim 11 wherein the control means includes a movable cam and the first means comprises drive means for said cam.
14. Apparatus according to Claim 11 wherein the control means includes a movable cam and the second means comprises a surface profile of the cam which, in use, is followed by a cam follower connected to the atomizing device by mechanical connection.
15. Apparatus according to Claim 12 wherein the control means includes a movable cam and the third means comprises a surface profile of the cam which, in use, is translated into amplitude of oscillation by a cam follower connected to the atomizing device by mechanical connection.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858527852A GB8527852D0 (en) | 1985-11-12 | 1985-11-12 | Atomization of metals |
| GB8527852 | 1985-11-12 | ||
| GB8527853 | 1985-11-12 | ||
| GB858527853A GB8527853D0 (en) | 1985-11-12 | 1985-11-12 | Metal product production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1268313A true CA1268313A (en) | 1990-05-01 |
Family
ID=26289995
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000522809A Expired CA1268313A (en) | 1985-11-12 | 1986-11-12 | Atomisation of metals |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1268313A (en) |
-
1986
- 1986-11-12 CA CA000522809A patent/CA1268313A/en not_active Expired
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| Date | Code | Title | Description |
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| MKLA | Lapsed |