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WO2000045980A1 - Fonte de metal - Google Patents

Fonte de metal Download PDF

Info

Publication number
WO2000045980A1
WO2000045980A1 PCT/SG2000/000012 SG0000012W WO0045980A1 WO 2000045980 A1 WO2000045980 A1 WO 2000045980A1 SG 0000012 W SG0000012 W SG 0000012W WO 0045980 A1 WO0045980 A1 WO 0045980A1
Authority
WO
WIPO (PCT)
Prior art keywords
crucible
metal
molten metal
electrode
mould
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.)
Ceased
Application number
PCT/SG2000/000012
Other languages
English (en)
Inventor
Peng Chum Loh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Singapore Polytechnic
Original Assignee
Singapore Polytechnic
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Singapore Polytechnic filed Critical Singapore Polytechnic
Priority to EP00906851A priority Critical patent/EP1163067A4/fr
Priority to AU28406/00A priority patent/AU2840600A/en
Publication of WO2000045980A1 publication Critical patent/WO2000045980A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D23/00—Casting processes not provided for in groups B22D1/00 - B22D21/00
    • B22D23/06—Melting-down metal, e.g. metal particles, in the mould

Definitions

  • the present invention relates to a method and apparatus for producing a metal casting, particularly but not exclusively for the jewellery industry.
  • An object of the present invention is to provide a method and apparatus which is capable of overcoming or at least ameliorating some of the difficulties encountered especially in the jewellery industry when casting using conventional processes and apparatus.
  • a method for producing a metal casting comprising, providing a metal in a crucible; melting the metal m the crucible under an inert atmospnere using an arc from an electrode; and releasing the molten metal into a mould.
  • the arc may produce a plasma temperature of around 10,000°C, and is thus able to heat the metal very rapidly and at least to a degree sufficient to melt all metals.
  • the metal m the crucible may comprise at least two parts of different compositions.
  • one part may comprise a gold-rich alloy and another part may comprise an aluminium-rich alloy.
  • the two parts may be alloyed together m the crucible. Alloying zn si tu may require stirring the molten metal m the crucible to give a homogenous melt. Stirring may be achieved by establishing relative movement between the arc and the crucible, possibly by oscillating the electrode. Preferably, the electrode does not contact the molten metal.
  • the molten metal may also be agitated m the crucible by supplying to the electrode a pulsating alternating current of varying frequency, e.g., 0-50 HZ Such current agitation encourages homogeneity in the molten metal. It may be advantageous to superimpose a direct current bias to the alternating current m order to shift the balance. By adding a positive direct current bias, the arc is predominantly positive which may clean the molten metal. Such electric cleaning (ion-bombardment) enables use of materials with inherent oxides, for example aluminium alloy. It could also be used to recycle contaminated eld jewellery. Alternatively, by introducing a negative direct current bias, the arc will predominantly be negative which may give rise to greater heating of the metal in the crucible.
  • the method for producing a metal casting may further comprise varying the pressure of the inert atmosphere during melting.
  • By exerting positive or negative gas pressures on the molten metal it is possible to lower surface tensions or remove trapped gases.
  • negative gas pressures to remove trapped gases it is desirable to remove evolving vapours possibly by maintaining a supply of inert gas to purge the inert atmosphere around the molten metal.
  • a negative pressure suction
  • Such a pressure differential may encourage molten metal flow from the crucible to the mould.
  • apparatus for producing a metal casting comprising a crucible, means for establishing an inert atmosphere around metal in the crucible, an electrode, means for supplying electricity to the electrode to generate an arc for melting metal m the crucible, and a mould for receiving molten metal from the crucible.
  • the inert atmosphere establishing means may simply comprise a flow of inert gas directed from the electrode towards metal in the crucible. The flow should be sufficient to establish an inert gas shield around metal m the crucible and preferably from the electrode to metal m the crucible.
  • the inert atmosphere establishing means may include a pressure chamber in which the electrode and metal m the crucible are located. The pressure chamber enables the pressure of the inert atmosphere to be decreased for removing trapped gases in the molten metal, and subsequently increased to lower molten metal surface tension.
  • the pressure chamber may have means for changing the inert atmosphere without altering gas pressure m the pressure chamber.
  • an outgoing flow of inert gas contaminated w th vapours evolved from the molten metal may be matched by an incoming flow of uncontammated inert gas.
  • the apparatus may further comprise a conduit communicating between the crucible and the mould, and having a valve for regulating molten metal flow through the conduit.
  • the apparatus may be arranged with the crucible above the mould so that molten metal flow through the conduit is aided by gravity, the molten metal flow through the conduit may further be encouraged by establishing a pressure differential across the "valve.
  • a vacuum pump may be used to lower gas pressure m the mould prior to opening the valve.
  • the crucible or the mould may be of graphite.
  • a graphite crucible would be able to carry a high current and at the same time additional heating and subsequently some cooling by thermal conduction would be possible.
  • a graphite mould would facilitate preheating of the mould before molten metal is introduced into it .
  • the graphite mould may be heated by electric heating elements.
  • Graphite is much less reactive than certain other mould materials, and thus is compatible with the more reactive jewellery compositions.
  • Figure 1 is a schematic showing manual apparatus embodying the present invention
  • Figure 2 is a section of automated apparatus embodying the present invention.
  • Figure 1 shows schematically manual apparatus 10 for producing cast jewellery, comprising a tungsten inert gas
  • the TIG hand torch 12 has a tungsten electrode
  • the inert gas shield 22 is provided by a flow of inert gas directed through the TIG hand torch 12 and beyond the electrode 20.
  • the graphite crucible 14 communicates with the mould 16 through conduit 24 when opened by graphite tap rod 26.
  • a metal sample 28 to be cast, or a mixture of metal samples 28 to be alloyed and then cast, are placed in the crucible 14.
  • the tap red 26 is positioned to seal off the conduit 24, blocking communication between the crucible 14 and the mould 16.
  • the TIG hand torch 12 is energized by the high frequency alternating current supply 30. The arc thus generated strikes the sample (s) 28 and rapidly produces molten metal.
  • the molten metal is agitated by pulsing of the arc caused by the alternating current.
  • the balance of alternating current is adjusted by superimposing a direct current supply 32.
  • the DC supply 32 may be switched between positive and negative, to make respectively the alternating current supplied to the electrode 20 either predominantly positive or predominantly negative.
  • the molten metal is further agitated by a stirring action imparted by oscillating the TIG hand torch 12; the electrode 20 does not contact the molten metal.
  • the graphite mould 16 is preheated by heating elements 34.
  • the pressure of gas in the mould 16 is reduced by a vacuum unit 36 which withdraws gas through suction hole 38.
  • tap rod 26 is moved to allow molten metal to flow through conduit 24 into the mould 16 where it is allowed to cool.
  • Figure 2 shows a section of an automated jewellery casting apparatus 50.
  • the apparatus 50 which are in common with the manual apparatus 10 of figure 1 have been given the same reference numerals.
  • the tungsten electrode 20 of a pulsating arc torch 52 and the crucible 14 are mounted in a pressure chamber 54 which is connected to vacuum pump 56 through coolant unit 58.
  • the pressure chamber 54 is supplied with inert gas through supply hose 60.
  • the pulsating arc torch 52 is connected to a mctcrised cam which in use causes the electrode 20 to oscillate in such a way that stirring of molten metal in the crucible 14 is achieved.
  • the separation of the electrode 20 from the crucible 14 is varied by adjusting the length of support struts 64.
  • the pressure chamber 54 is sealed. 3) The graphite mould 16 is preheated (the graphite crucible 14 may also be preheated) .
  • the pressure chamber 54 is purged with argon inert gas.
  • the gas pressure in the pressure chamber 54 is balanced at between 10 and 10 ⁇ ' torr, with the graphite mould 16 at about 300°C. 7)
  • the AC pulsed arc (argon-tungsten) is started using the high frequency supply.
  • the motorised cam 62 is started to oscillate the torch 52.
  • the alloying elements are melted in the crucible, cleaned using the predominantly positive (DC biased) arc using ion bombardment to break up intermetailic oxides and the like, and homogenized by stirring and agitating.
  • impurities and oxides of the alloying elements are transformed into vapours and removed by continuous action of the unit 56.
  • the purified and homogenized molten alloy is then cast into the graphite mould 16 (pre-purged with inert argon) .
  • the pressure in the chamber 54 is increased and at the same time, the pressure in the mould 16 is decreased by suction through hole 38. 12)
  • the cast metal is allowed to cool.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Display Devices Of Pinball Game Machines (AREA)

Abstract

Dispositif (10) de fonte de métal composé d'une lampe à main (12) fonctionnant au gaz inerte de tungstène (TIG), d'un creuset (14) en graphite et d'un moule (16) en graphite, Lorsqu'elle est excitée par un courant alternatif haute fréquence provenant d'une alimentation (30), la lampe (12) produit un arc pulsé à l'intérieur d'un écran (22) de gaz inerte. L'arc fait fondre le métal (28) contenu dans le creuset (14) et l'enlèvement du métal fondu s'effectue par superposition d'une polarisation positive de courant continu sur le courant alternatif. On peut mélanger différents métaux afin d'obtenir un alliage, dont l'homogénéité résulte de l'agitation du métal en fusion. On verse le métal en fusion dans un moule (16) par le conduit (24) et par ouverture du robinet (26).
PCT/SG2000/000012 1999-02-02 2000-01-31 Fonte de metal Ceased WO2000045980A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP00906851A EP1163067A4 (fr) 1999-02-02 2000-01-31 Fonte de metal
AU28406/00A AU2840600A (en) 1999-02-02 2000-01-31 Metal casting

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SG9900057A SG87016A1 (en) 1999-02-02 1999-02-02 Metal casting
SG9900057-2 1999-02-02

Publications (1)

Publication Number Publication Date
WO2000045980A1 true WO2000045980A1 (fr) 2000-08-10

Family

ID=20430219

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SG2000/000012 Ceased WO2000045980A1 (fr) 1999-02-02 2000-01-31 Fonte de metal

Country Status (4)

Country Link
EP (1) EP1163067A4 (fr)
AU (1) AU2840600A (fr)
SG (1) SG87016A1 (fr)
WO (1) WO2000045980A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140076627A (ko) * 2011-11-02 2014-06-20 다이아배큠 가부시키가이샤 아크 용해로 장치 및 피용해물의 아크 용해 방법
WO2018022712A1 (fr) * 2016-07-28 2018-02-01 Arconic Inc. Système et procédé de fusion et de coulée en deux étapes

Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1035875A (en) * 1963-08-16 1966-07-13 Ibm Intermetallic compounds and their preparation
US3683094A (en) * 1971-02-18 1972-08-08 Max P Schlienger Arc positioning system for rotating electrode wheel arc furnace
SU429099A1 (ru) * 1972-05-18 1974-05-25 Чел бинский металлургический завод СПОСОБ ВЕДЕНИЯ ПЛАВКИ В ЭЛЕКТРОПЕЧИФШ|Д йбги:*:ь,л 1>&^--^ ,,r>&s--±-^-'?g;?^y
US4110546A (en) * 1975-11-06 1978-08-29 Asea Aktiebolag DC arc furnace having a rotating arc
EP0018450A1 (fr) * 1979-04-25 1980-11-12 Iwatani Sangyo Kabushiki Kaisha Dispositif de coulée
JPS56151162A (en) * 1980-04-25 1981-11-24 Nakaseko Isao Argon arc pressurizing casting machine
US4572673A (en) * 1982-02-12 1986-02-25 British Steel Corporation Treatment of molten materials
US4670884A (en) * 1984-09-18 1987-06-02 Italo Letizia Rotating carbon or graphite electrode column to be used both in open- and submerged-arc furnaces
US4700769A (en) * 1985-06-18 1987-10-20 Ohara Co., Ltd. Casting apparatus for titanium or titanium alloy
JPS63144855A (ja) * 1986-12-10 1988-06-17 Nkk Corp 滴下式鋳造方法
US5168917A (en) * 1990-05-18 1992-12-08 Gc Corporation Casting of dental metals
US5846287A (en) * 1993-08-05 1998-12-08 Cabot Corporation Consumable electrode method for forming micro-alloyed products
US5956366A (en) * 1997-02-26 1999-09-21 Nkk Steel Engineering, Inc. Arc furnace and method in which molten material is stirred and the arc is guided
US5963579A (en) * 1997-08-11 1999-10-05 Sollac Method of heating a molten metal in a continuous casting tundish using a plasma torch, and tundish for its implementation

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1035875A (en) * 1963-08-16 1966-07-13 Ibm Intermetallic compounds and their preparation
US3683094A (en) * 1971-02-18 1972-08-08 Max P Schlienger Arc positioning system for rotating electrode wheel arc furnace
SU429099A1 (ru) * 1972-05-18 1974-05-25 Чел бинский металлургический завод СПОСОБ ВЕДЕНИЯ ПЛАВКИ В ЭЛЕКТРОПЕЧИФШ|Д йбги:*:ь,л 1>&^--^ ,,r>&s--±-^-'?g;?^y
US4110546A (en) * 1975-11-06 1978-08-29 Asea Aktiebolag DC arc furnace having a rotating arc
EP0018450A1 (fr) * 1979-04-25 1980-11-12 Iwatani Sangyo Kabushiki Kaisha Dispositif de coulée
JPS56151162A (en) * 1980-04-25 1981-11-24 Nakaseko Isao Argon arc pressurizing casting machine
US4572673A (en) * 1982-02-12 1986-02-25 British Steel Corporation Treatment of molten materials
US4670884A (en) * 1984-09-18 1987-06-02 Italo Letizia Rotating carbon or graphite electrode column to be used both in open- and submerged-arc furnaces
US4700769A (en) * 1985-06-18 1987-10-20 Ohara Co., Ltd. Casting apparatus for titanium or titanium alloy
JPS63144855A (ja) * 1986-12-10 1988-06-17 Nkk Corp 滴下式鋳造方法
US5168917A (en) * 1990-05-18 1992-12-08 Gc Corporation Casting of dental metals
US5846287A (en) * 1993-08-05 1998-12-08 Cabot Corporation Consumable electrode method for forming micro-alloyed products
US5956366A (en) * 1997-02-26 1999-09-21 Nkk Steel Engineering, Inc. Arc furnace and method in which molten material is stirred and the arc is guided
US5963579A (en) * 1997-08-11 1999-10-05 Sollac Method of heating a molten metal in a continuous casting tundish using a plasma torch, and tundish for its implementation

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Derwent World Patents Index; Class M24, AN 18928W/11 *
PATENT ABSTRACTS OF JAPAN *
See also references of EP1163067A4 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140076627A (ko) * 2011-11-02 2014-06-20 다이아배큠 가부시키가이샤 아크 용해로 장치 및 피용해물의 아크 용해 방법
CN104023877A (zh) * 2011-11-02 2014-09-03 大亚真空株式会社 电弧熔化炉装置以及被熔化物的电弧熔化方法
EP2774702A4 (fr) * 2011-11-02 2015-04-01 Diavac Ltd Four de fusion à arc et procédé de fusion à arc pour substance à fondre
JPWO2013065378A1 (ja) * 2011-11-02 2015-04-02 大亜真空株式会社 アーク溶解炉装置及び被溶解物のアーク溶解方法
KR101634887B1 (ko) * 2011-11-02 2016-06-29 다이아배큠 가부시키가이샤 아크 용해로 장치 및 피용해물의 아크 용해 방법
WO2018022712A1 (fr) * 2016-07-28 2018-02-01 Arconic Inc. Système et procédé de fusion et de coulée en deux étapes
CN109477162A (zh) * 2016-07-28 2019-03-15 奥科宁克有限公司 两级熔化以及铸造系统和方法

Also Published As

Publication number Publication date
SG87016A1 (en) 2002-03-19
EP1163067A4 (fr) 2003-07-30
AU2840600A (en) 2000-08-25
EP1163067A1 (fr) 2001-12-19

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