EP0457502B1 - Dispositif et procédé pour couler avec précision - Google Patents

Dispositif et procédé pour couler avec précision Download PDF

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Publication number
EP0457502B1
EP0457502B1 EP19910304192 EP91304192A EP0457502B1 EP 0457502 B1 EP0457502 B1 EP 0457502B1 EP 19910304192 EP19910304192 EP 19910304192 EP 91304192 A EP91304192 A EP 91304192A EP 0457502 B1 EP0457502 B1 EP 0457502B1
Authority
EP
European Patent Office
Prior art keywords
base metal
assembly
casting
precision casting
titanium
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 - Lifetime
Application number
EP19910304192
Other languages
German (de)
English (en)
Other versions
EP0457502A1 (fr
Inventor
Noboru Demukai
Shingo Hitotsuyanagi
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.)
Daido Steel Co Ltd
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Daido Steel Co Ltd
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Publication date
Application filed by Daido Steel Co Ltd filed Critical Daido Steel Co Ltd
Publication of EP0457502A1 publication Critical patent/EP0457502A1/fr
Application granted granted Critical
Publication of EP0457502B1 publication Critical patent/EP0457502B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/06—Vacuum casting, i.e. making use of vacuum to fill the mould

Definitions

  • This invention relates to a method and an apparatus for precision casting, in particular for obtaining precision castings of titanium or titanium alloy which have excellent heat and corrosion resistance properties, in addition to lightness and very high strength.
  • Titanium and titanium alloys are light, and have excellent heat resistance, corrosion resistance and mechanical strength. It is expected to obtain useful products which have not been used so far, by precision casting base metals, such titanium or titanium alloy, in accordance with the present invention.
  • titanium or titanium alloy has a melting point higher than 1400°C and is also active, there is a problem in that there are great difficulties in melting and casting titanium or titanium alloy in the majority of cases.
  • GB-A-2204816 discloses an apparatus for and method of countergravity casting of metals which comprises the induction melting of a metal in a crucible and vacuum casting into a gas permeable mould.
  • This invention aims to solve or at least partially to alleviate the above-mentioned problems of the prior art.
  • the present invention provides a method of precision casting comprising: establishing molten base metal by induction heating; casting said molten base metal into a permeable mold disposed above the molten base metal by vacuum casting; characterised in that the base metal is selected from titanium, tungsten, molybdenum, vanadium, zirconium, lithium, or alloys thereof; and in that the base metal is heated by induction in an assembly formed with a plurality of water cooled copper segments disposed circlewise on the inside of an induction heating coil in a state in which said copper segments are insulated from each other.
  • the base metal may be melted in an atmosphere of an inert gas such as argon and the molten metal may be cast into the permeable mold through a tubular sprue.
  • the base metal alloy may be fed continuously into the assembly formed with the water cooled segments from the underside of the assembly.
  • the present invention also provides a precision casting apparatus comprising: an induction heating coil; a permeable mold for vacuum casting; characterised in that an assembly formed with a plurality of water cooled copper segments is disposed circlewise on an inside of said induction heating coil in a state in which said copper segments are insulated from each other, said assembly being fed with a base metal from an underside thereof; and said base metal being melted by induction heating on the inside of said assembly.
  • the permeable mold may be provided with a plurality of tubular sprues for conducting the molten base metal thereinto at the time of vacuum casting, and a closed feeder head in an upper part thereof.
  • the permeable mold may be a ceramic shell mold.
  • the precision casting apparatus of the present invention can be used for casting a base metal selected from titanium, tungsten, molybdenum, vanadium, zirconium, lithium, or alloys thereof.
  • eddy currents are induced on the inside of the assembly formed with water cooled copper segments disposed circlewise on the inside of the induction coil.
  • the water cooled copper segments are insulated from each other at the time of melting the base metal in the assembly.
  • the base metal is melted by an eddy current induced in the outer layer thereof by the above-mentioned eddy currents which are alternating currents.
  • the molten base metal is detached from the assembly formed with the water cooled copper segments by repelling forces caused by currents which have opposite phases to each other flowing in the outermost layers of the assembly and the molten metal.
  • a gap is formed between the molten metal and the inner periphery of the assembly.
  • a thick-walled skull (a layer of solidified metal) is scarcely formed, differing from the cases of conventional furnaces of a water cooled hearth type such as an arc skull crucible furnace.
  • the base metal which is melted thus has a better yield. It is easy to regulate the temperature of the molten metal by controlling the electric energy supplied to the induction coil.
  • the molten base metal is not contaminated substantially because a ceramic crucible composed of oxides is not used, and precision castings of good quality can be obtained.
  • a precision casting apparatus in accordance with an embodiment of the present invention which is used for precision casting of titanium or titanium alloy is shown in Figures 1 and 2.
  • the precision casting apparatus 1 is provided with an assembly 2 in the center part thereof which is formed with a plurality of water cooled copper segments 2a, 2b,...2h disposed circlewise in the state insulated from each other through insulations 7.
  • the respective water cooled copper segments 2, 2b,...2h are provided with water pipes 3a, 3b,...3h.
  • the assembly 2 is provided continuously with a magnetic shield 4 on the upper side thereof.
  • the assembly 2 has a radio-frequency induction coil 5 disposed on the outside thereof and is designed to allow base metal 6 of titanium or titanium alloy to be fed to the inside from an underside thereof.
  • the magnetic shield 4 is provided with a circular base 11 through a seal 12 on the upper side thereof.
  • a sleeve 13 is provided on the inside of the circular base 11, and a mold chamber 14 is provided on the inside of the sleeve 13.
  • a melting space 15 is formed in a part surrounded by the bottom face of the mold chamber 14 and inner peripheries of the assembly 2 and the magnetic shield 4. It is possible to replace the atmosphere in the melting space 15 with an inert gas by, for example, supplying argon through a gas intake 16 provided on the circular base 11.
  • a permeable mold 21 which is a ceramic shell mold is disposed in the mold chamber 14.
  • a turbine wheel-shaped molding cavity 21a in the permeable mold 21 and the melting space 15 are connected by a gate 22 formed in the permeable mold 21.
  • a tubular sprue 23 communicates with the gate 22.
  • the permeable mold 21 is provided with a closed feeder head 21c in the upper part thereof, and has a heat insulator 24 having gas permeability disposed on the outer surface thereof.
  • the mold chamber 14 is provided with an upper plate 27 through a seal 26 on the upper end thereof.
  • the permeable mold 21 is held with a support 29 piercing the upper plate 27 through a seal 28, and the upper plate 27 is provided with a suction hold 27a.
  • eddy currents are formed on the inside of the assembly 2 by radio-frequency induction of the radio-frequency induction coil 5.
  • the base metal 6 of titanium or titanium alloy is melted by an eddy current induced in the outer layer of the base metal 6.
  • the eddy currents are alternating currents.
  • the molten metal 31 of titanium or titanium alloy is slightly separated from the inner periphery of the assembly 2 by repelling forces caused by the currents flowing in the outermost layers of the assembly 2 and the molten metal 31 which have opposite phases to each other. A gap is formed between the molten metal 31 and the assembly 2.
  • thermal transmission from the molten metal 31 of titanium or titanium alloy to the assembly 2 is suppressed by the formation of the gap.
  • a thick-walled skull which is formed in conventional furnaces of a water cooled hearth type, such as an arc skull crucible furnace, is scarcely formed. It becomes possible to melt the base metal 6 of titanium or titanium alloy with a better yield. It also becomes possible to regulate the temperature of the molten metal 31 of titanium or titanium alloy easily by controlling the electric energy supplied to the radio-frequency induction coil 5. Furthermore, there is practically no contamination of the molten metal 31 since a ceramic crucible composed of oxides is not used.
  • a cast product is obtained by shakeout after solidification of the molten metal 31 in the permeable mold 21.
  • Ti-Al intermetallic compound which is light and excellent in mechanical strength at high temperature was chosen as a base metal 6, and cast into a turbine wheel for a turbo charger which is 1200g in finished weight with an outside diameter of 140mm.
  • the high-frequency generator used in this embodiment for supplying a high-frequency wave to the induction heating coil 5 is a small and comparatively simplified type having capacity of 60kW.
  • the frequency is high, as much as 30kHz, so that it is possible to melt materials with small diameters efficiently.
  • the turbine wheel has twelve turbine blades and twelve gates 22 having diameters of 8mm provided near the lower parts of respective turbine blades.
  • the base metal 6 composed of Ti-Al intermetallic compound was fed from the underside of the assembly 2 formed with water cooled copper segments 2a, 2b,...2h, and heated by supplying the high-frequency wave of 60kW with frequency of 30kHz to the induction heating coil 5.
  • the base metal 6 is melted by forming eddy currents on the inside of the assembly 2 and inducing an eddy current in the outermost layer of the base metal 6 of Ti-Al alloy.
  • the casting temperature was determined at 1580°C by making the temperature of the molten metal 31 higher than the melting point 1520°C of the Ti-Al alloy by 60°C (superheat).
  • the degree of superheat is remarkably low as compared with that of top poured conventional precision casting (150 ⁇ 250°C), and is effective for inhibiting the reaction between the permeable mold 21 and the molten metal 31.
  • the gas in the molding cavity 21a can be discharged through the permeable mold 21 according to the difference of the internal pressures between the mold chamber 14 and the melting space 15.
  • the molten metal 31 of Ti-Al alloy is drawn by suction into the molding cavity 21a and the feeder head 21c through the tubular sprue 23 and the gates 22.
  • the turbine wheel is obtained by solidifying the molten metal 31 in the molding cavity 21a.
  • the molten metal 31 As the molten metal 31 is drawn into the molding cavity 21a by vacuum casting, the molten metal 31 spreads well into every nook and corner of the thin-walled turbine blade mold. It is thus possible to obtain a turbine wheel with high accuracy in shape.
  • Adopting the method and apparatus for precision casting according to this invention it becomes possible to manufacture complicated and large-sized precision castings which previously have been almost impossible to make.
  • the invention will contribute much to the further development of the precision casting of titanium or titanium alloy.
  • the method for precision casting comprises the step of establishing molten base metal of, for example, titanium or titanium alloy by induction heating in an assembly formed with a plurality of water cooled copper segments disposed circlewise on the inside of an induction heating coil in a state in which the copper segments are insulated from each other, and casting the molten base metal into a permeable mold disposed above the molten base metal by vacuum casting.
  • the molten base metal is detached from the assembly.
  • a gap is formed between the molten metal and the assembly by repelling forces caused by currents flowing in the outermost layers of the assembly and the molten metal which have opposite phases to each other.
  • the base metal is melted by an eddy current induced in the outer layer thereof by eddy currents which are alternating currents at the time of melting the base metal. Excellent effects can be obtained in that the yield rate of the base metal is improved remarkably, and the control of the temperature of the molten metal is facilitated. It is also possible to prevent the molten metal from being contaminated and to obtain precision castings of good quality because the thermal transmission from the molten metal to the assembly is suppressed preventing the formation of a solidified metal layer between the molten metal and the assembly.
  • the precision casting apparatus comprises an induction heating coil, an assembly formed with a plurality of water cooled copper segments disposed circlewise on the inside of said induction heating coil in a state in which the copper segments are insulated from each other, and fed with base metal of, for example, titanium or titanium alloy from the underside thereof, and a permeable mold for casting the base metal which is melted by induction heating on the inside of the assembly formed with the water cooled copper segments by means of vacuum casting. Therefore, an excellent effect can be obtained since it becomes possible to manufacture precision castings accurately with a better yield by enabling execution of the aforementioned method for precision casting.
  • the preferred embodiments of the present invention can provide a method and an apparatus for precision metals with high melting points or high activity by preventing the molten metal from contamination in melting, maintaining the quality and the temperature of the molten metal required for casting, and casting the molten metal under the forced casting condition suitable to prevent the misrun of the molten metal even if the molten metal is cast at low temperature at the time of carrying out the precision casting.
  • the metals typically include titanium, titanium alloy or other metals having high melting points or high activities such as tungsten, molybdenum, vanadium, zirconium or lithium.

Claims (9)

  1. Procédé de coulage de précision comprenant les phases consistant à :
       produire un métal de base fondu par chauffage à induction;
       couler ledit métal de base fondu dans un moule perméable (21) disposé au-dessus du métal de base fondu par coulage sous vide;
       caractérisé en ce que le métal de base est sélectionné parmi le titane, le tungstène, le molybdène, le vanadium, le zirconium, le lithium, ou des alliages de ceux-ci; et en ce que le métal de base est chauffé par induction dans un ensemble (2) doté d'une pluralité de segments de cuivre refroidis par eau (2a-h) disposés en cercle à l'intérieur d'une bobine de chauffage à induction (5) dans une condition où lesdits segments de cuivre (2a-h) sont isolés les uns des autres.
  2. Procédé de coulage de précision selon la revendication 1, dans lequel ledit métal de base est fondu dans une atmosphère de gaz inerte tel que l'argon.
  3. Procédé de coulage de précision selon la revendication 1 ou 2, dans lequel ledit métal de base fondu est coulé dans le moule perméable (21) via un canal tubulaire (23).
  4. Procédé de coulage de précision selon l'une quelconque des revendications 1 à 3, dans lequel ledit métal de base est distribué en continu dans l'ensemble (2) doté de la pluralité de segments de cuivre refroidis par eau (2a-h) depuis le dessous dudit ensemble (2).
  5. Appareil de coulage de précision comprenant :
       une bobine de chauffage à induction (5);
       un moule perméable (21) pour le coulage sous vide;
       caractérisé en ce qu'un ensemble (2) doté d'une pluralité de segments de cuivre refroidis par eau (2a-h) est disposé en cercle sur l'intérieur de ladite bobine de chauffage à induction (5) dans une condition où lesdits segments de cuivre (2a-h) sont isolés les uns des autres, ledit ensemble (2) étant alimenté en un métal de base depuis le dessous; et ledit métal de base étant fondu par chauffage à induction sur l'intérieur dudit ensemble (2).
  6. Appareil de coulage de précision selon la revendication 5, dans lequel ledit moule perméable (21) est doté d'une pluralité de canaux tubulaires (23) pour conduire le métal de base fondu en son sein au moment du coulage sous vide.
  7. Appareil de coulage de précision selon la revendication 5 ou 6, dans lequel ledit moule perméable (21) est doté d'une tête d'alimentation fermée (21c) dans une partie supérieure.
  8. Appareil de coulage de précision selon l'une quelconque des revendications 5 à 7, dans lequel ledit moule perméable (21) est un moule carapace en céramique.
  9. Utilisation d'un appareil de coulage de précision selon l'une quelconque des revendications 5 à 8, pour couler un métal de base sélectionné parmi le titane, le tungstène, le molybdène, le vanadium, le zirconium, le lithium, ou des alliages de ceux-ci.
EP19910304192 1990-05-15 1991-05-09 Dispositif et procédé pour couler avec précision Expired - Lifetime EP0457502B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP124383/90 1990-05-15
JP2124383A JP2541341B2 (ja) 1990-05-15 1990-05-15 Ｔｉ，Ｔｉ合金の精密鋳造方法および精密鋳造装置

Publications (2)

Publication Number Publication Date
EP0457502A1 EP0457502A1 (fr) 1991-11-21
EP0457502B1 true EP0457502B1 (fr) 1995-10-11

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EP19910304192 Expired - Lifetime EP0457502B1 (fr) 1990-05-15 1991-05-09 Dispositif et procédé pour couler avec précision

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EP (1) EP0457502B1 (fr)
JP (1) JP2541341B2 (fr)
DE (1) DE69113676T2 (fr)
ES (1) ES2080897T3 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2830777B2 (ja) * 1995-04-25 1998-12-02 大同特殊鋼株式会社 金属の鋳造方法とその装置
US5722481A (en) * 1995-06-20 1998-03-03 Daido Tokushuko Kabushiki Kaisha Method for casting metal and apparatus therefor
TW297050B (fr) * 1995-05-19 1997-02-01 Daido Steel Co Ltd
EP1696043A1 (fr) * 2005-02-25 2006-08-30 WALDEMAR LINK GmbH & Co. KG Procédé de couler un alliage a base de titan
CN112916831B (zh) * 2021-01-25 2022-07-26 中国科学院金属研究所 一种具有片层界面择优定向及细小层片特征的γ-TiAl合金的制备方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4112997A (en) * 1977-02-28 1978-09-12 Hitchiner Manufacturing Co., Inc. Metal casting
US4196769A (en) * 1978-03-20 1980-04-08 Remet Corporation Ceramic shell mold
SE444124B (sv) * 1978-10-02 1986-03-24 Hitchiner Manufacturing Co Sett att gjuta metall samt gaspermeabel form for genomforande av settet
IN170880B (fr) * 1987-05-07 1992-06-06 Metal Casting Tech
JPH0259168A (ja) * 1988-08-25 1990-02-28 Reiichi Okuda 精密鋳造方法

Also Published As

Publication number Publication date
DE69113676D1 (de) 1995-11-16
ES2080897T3 (es) 1996-02-16
EP0457502A1 (fr) 1991-11-21
JP2541341B2 (ja) 1996-10-09
DE69113676T2 (de) 1996-04-18
JPH0422562A (ja) 1992-01-27

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