EP0457502A1 - Method and apparatus for precision casting - Google Patents
Method and apparatus for precision casting Download PDFInfo
- Publication number
- EP0457502A1 EP0457502A1 EP91304192A EP91304192A EP0457502A1 EP 0457502 A1 EP0457502 A1 EP 0457502A1 EP 91304192 A EP91304192 A EP 91304192A EP 91304192 A EP91304192 A EP 91304192A EP 0457502 A1 EP0457502 A1 EP 0457502A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- titanium
- titanium alloy
- casting
- base metal
- molten
- 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.)
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Links
- 238000005495 investment casting Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 16
- 229910001069 Ti alloy Inorganic materials 0.000 claims abstract description 52
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000010936 titanium Substances 0.000 claims abstract description 52
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 51
- 239000010953 base metal Substances 0.000 claims abstract description 41
- 238000005266 casting Methods 0.000 claims abstract description 30
- 230000006698 induction Effects 0.000 claims abstract description 27
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229910052802 copper Inorganic materials 0.000 claims abstract description 25
- 239000010949 copper Substances 0.000 claims abstract description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000010438 heat treatment Methods 0.000 claims abstract description 18
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 44
- 239000002184 metal Substances 0.000 abstract description 44
- 238000002844 melting Methods 0.000 abstract description 16
- 230000008018 melting Effects 0.000 abstract description 16
- 230000000694 effects Effects 0.000 abstract description 6
- 150000002739 metals Chemical class 0.000 abstract description 4
- 238000000465 moulding Methods 0.000 description 9
- 208000015943 Coeliac disease Diseases 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000011109 contamination Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 210000003625 skull Anatomy 0.000 description 4
- 229910004349 Ti-Al Inorganic materials 0.000 description 3
- 229910004692 Ti—Al Inorganic materials 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 230000001846 repelling effect Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- 229910021362 Ti-Al intermetallic compound Inorganic materials 0.000 description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000000289 melt material Substances 0.000 description 1
- 238000005058 metal casting Methods 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Images
Classifications
-
- 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 castings of titanium or titanium alloy applicable for obtaining precision castings of titanium or titanium alloy which is excellent in heat-resisting property and corrosion resistance in addition to its lightness, and has very high strength.
- Titanium and titanium alloy are light and excellent in heat and corrosion resistance, further in mechanical strength, therefore it is expected to obtain useful products which has not been used so far by casting precisely such titanium or titanium alloy.
- the 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 the titanium or titanium alloy in the majority of cases.
- 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 for precision casting of titanium or titanium alloy which comprises establishing molten base metal of 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 vaccum casting.
- the base metal may be molten in an atomosphere of an inert gas such as argon and may be cast into the permeable mold through a tubular sprue, and the base metal of titanium or titanium alloy may be fed continuously into the assembly formed with the water cooled segments from the under side of the assembly.
- an inert gas such as argon
- the present invention also provides a precision casting apparatus for titanium or titanium alloy comprising a induction heating coil, an assembly formed with a plurality of water cooled copper segments disposed circlewise on the inside of the induction heating coil in a state in which the copper segments are insulated from each other, and fed with base metal of titanium or titanium alloy from the under side thereof, and a permeable mold for casting the base metal molten by induction heating on the inside of the assembly formed with the water cooled copper segments by means of vacuum casting.
- 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 the upper part thereof, and the permeable mold may be a ceramic shell mold.
- eddy currents are formed on the inside of the assembly formed with water cooled copper segments disposed circlewise on the inside of the induction coil in the state insulated from each other at the time of melting the base metal of titanium or titanium alloy in the assembly formed with the water cooled copper segments.
- the base metal is molten by an eddy current induced in the outer layer thereof by the abovementioned eddy currents which are alternating currents, in this time the molten base metal is detached from the assembly formed with the water cooled copper segments by repelling force caused by currents flowing in the outermost layers of the assembly and the molten metal and having opposite phases each other, and 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 and so on, for example, and the base metal is molten in a better yield.
- a precision casting apparatus which is used in an embodiment of the method for precision casting of titanium or titanium alloy according to this inveniton is shown in Figure 1 and Figure 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, and the respective water cooled copper segments 2a, 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 is disposed with a radio-frequency induction coil 5 on the outside thereof and so designed as to fed base metal 6 of titanium or titanium alloy on the inside from under side thereof.
- the magnetic shield 4 is provided with a circlar base 11 through a seal 12 on the upper side thereof and provided with a sleeve 13 on the inside of the circlar base 11, and a mold chamber 14 is provided on the inside of the sleeve 13.
- 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, and it is possible to replace the atomosphere in the melting space 15 with an inert gas by supplying argon through a gas intake 16 provided on the circlar base 11, for example.
- a permeable mold 21 which is a ceramic shell mold is disposed in the mold chamber 14, and a turbine wheelshaped 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 and a tubular sprue 23 communicating to the gate 22.
- the permeable mold 21 is provided with a closed feeder head 21c in the upper part thereof, and disposed with a heat insulator 24 having gas permeability 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 and 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 hole 27a.
- eddy currents are formed on the inside of the assembly 2 by radio frequency induction of the radio-frequency induction coil 5, and the base metal 6 of titanium or titanium alloy is molten by an eddy current induced in the outer layer of the base metal 6 by the eddy currents which 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 force caused by currents flowing in the outermost layers of the assembly 2 and the molten metal 31 and having opposite phases each other, and a gap is formed between the molten metal 31 and the assembly 2
- Ti-Al intermetallic compound which is light and excellent in mechanical strength at high temperature was chosen as base metal 6 of titanium or titanium alloy, and cast into a turbine wheel for turbo charger which is 1200g in finished weight with outside diameter of 140mm.
- the high-frequency generator used in this time for supplying high frequency wave to the induction heating coil 5 is a small and simplified type comparatively having capacity of 60kW. And 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 were provided near the lower parts of respective turbine blades in total.
- the base metal 6 composed of Ti-Al intermetallic compound was fed from the under side of the assembly 2 formed with water cooled copper segments 2a, 2b,...2h, and heated by supplying the high frequency wave of 60 kW with frequency of 30 kHz to the induction heating coil 5. And the base metal 6 was molten 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 in this time is remarkably low as compared with that of the top poured conventional precision casting (150 ⁇ 50°C), it is effective for inhibiting the reaction between the permeable mold 21 and the molten metal 31.
- the gas in the molding cavity 21a was discharged through the permeable mold 21 according to the difference of the internal pressures between the mold chamber 14 and the melting space 15, and the molten metal 31 of Ti-Al alloy was drawn by suction in the molding cavity 21a and the feeder head 21c through the tubular sprue 23 and the gates 22. And then the turbine wheel was obtained by solidifying the molten metal 31 in the molding cavity 21a.
- the molten metal 31 spreads well every nook and corner of the thinwalled turbine blade, and it was possible to obtain the turbine wheel with high accuracy in shape.
- Adopting the method and the apparatus for precision casting according to this invention it becomes possible to manufacture complicated and large-sized precision casting which has been impossible to be made substantially and the invention will contribute much to further development of the precision casting of titanium or titanium alloy. And in addition to above, it is possible to apply the method and the apparatus to presicion casting of metals or alloys of the metals having high melting points or high activity such as tungsten, molybdenum, vanadium, zirconium, lithium or the like.
- the method for precision casting of titanium or titanium alloy comprises the the step of establishing molten base metal of 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 premeable mold disposed above the molten base metal by vacuum casting.
- the molten base metal is deteched from the assembly and a gap is formed between the molten metal and the assembly by repelling force caused by currents flowing in the outermost layers of the assembly and the molten metal and having opposite phases each other because the base metal is molten by an eddy current induced in the outer layer thereof by eddy currents which are alternaing currents at the time of melting the base metal of titanium or titanium alloy.
- the precision casting apparatus for titanium or titanium alloy 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 titanium or titanium alloy from the under side thereof, and a permeable mold for casting tha base metal molten 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 the precision castings of titanium or titanium alloy with accuracy in a better yield by enabling execution of the aforementioned method for precision casting of titanium or titanium alloy.
- the preferred embodiments of the present invention can Provide a method and an apparatus for precision casting which is possible to obtain precision castings of metals with high melting points or high activity by preventing the molten metal from the contamination in the melting, maintaining the quantity and the temperature of the molten metal required for the 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 the low temperature at the time of carring out the precision casting of titanium, titanium alloy or other metals having high melting points or high activities such as tungsten, molybdenum, vanadium, zirconium, lithium or the like.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Furnace Details (AREA)
- General Induction Heating (AREA)
- Crucibles And Fluidized-Bed Furnaces (AREA)
Abstract
Description
- This invention relates to a method and an apparatus for precision castings of titanium or titanium alloy applicable for obtaining precision castings of titanium or titanium alloy which is excellent in heat-resisting property and corrosion resistance in addition to its lightness, and has very high strength.
- Titanium and titanium alloy are light and excellent in heat and corrosion resistance, further in mechanical strength, therefore it is expected to obtain useful products which has not been used so far by casting precisely such titanium or titanium alloy.
- However, because the 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 the titanium or titanium alloy in the majority of cases.
- Namely, when an ordinary ceramic crucible is used in order to melt the titanium or titanium alloy and obtain the quantity and temperature of the molten metal suitable for the casting, there is a problem in that oxide ceramics forming the crucible can be easily reduced by titanium at a high temperature. If a graphite crucible is used, there is another problem in that it is merely possible to carry out the melting in a small quantity for short time from a standpoint of preventing the titanium or titanium alloy from contamination because carbon dissolves into the titanium or titanium alloy. And, in regard to a mold for casting the molten metal of the titanium or titanium alloy thereinto, a reaction sometimes takes place between the mold and the molten metal. In this case, it is necessary to reduce the casting temperature as much as possible, however the molten metal is apt to solidify before the molding cavity is filled sufficiently with the molten metal in such a case and there is a different problem in that misrun of the molten metal is caused in precision castings having thin-walled and complicated shapes.
- 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 for precision casting of titanium or titanium alloy which comprises establishing molten base metal of 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 vaccum casting.
- In the preferred aspects according to this invention, the base metal may be molten in an atomosphere of an inert gas such as argon and may be cast into the permeable mold through a tubular sprue, and the base metal of titanium or titanium alloy may be fed continuously into the assembly formed with the water cooled segments from the under side of the assembly.
- The present invention also provides a precision casting apparatus for titanium or titanium alloy comprising a induction heating coil, an assembly formed with a plurality of water cooled copper segments disposed circlewise on the inside of the induction heating coil in a state in which the copper segments are insulated from each other, and fed with base metal of titanium or titanium alloy from the under side thereof, and a permeable mold for casting the base metal molten by induction heating on the inside of the assembly formed with the water cooled copper segments by means of vacuum casting.
- In the preferred aspects according to this invention, 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 the upper part thereof, and the permeable mold may be a ceramic shell mold.
- Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:-
- Figure 1 is a vertical sectional side view illustrating the precision casting apparatus according to an embodiment of this invention ; and
- Figure 2 is a horizontal sectional view of the assemble formed with the water cooled copper segments in the precision casting apparatus shown in Figure 1.
- In the method and the apparatus for precision casting of titanium or titanium alloy according to this invention having the aforementioned construction, eddy currents are formed on the inside of the assembly formed with water cooled copper segments disposed circlewise on the inside of the induction coil in the state insulated from each other at the time of melting the base metal of titanium or titanium alloy in the assembly formed with the water cooled copper segments.
- Therefore, the base metal is molten by an eddy current induced in the outer layer thereof by the abovementioned eddy currents which are alternating currents, in this time the molten base metal is detached from the assembly formed with the water cooled copper segments by repelling force caused by currents flowing in the outermost layers of the assembly and the molten metal and having opposite phases each other, and a gap is formed between the molten metal and the inner periphery of the assembly.
- Accordingly, thermal transmission from the molten metal to the assembly is suppressed by the formation of the gap, 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 and so on, for example, and the base metal is molten in a better yield. And , it is easy to regulate the temperature of molten metal by controlling electric energy to be 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 which is used in an embodiment of the method for precision casting of titanium or titanium alloy according to this inveniton is shown in Figure 1 and Figure 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 cooledcopper segments insulations 7, and the respective water cooledcopper segments water pipes 3a, 3b,...3h. Theassembly 2 is provided continuously with amagnetic shield 4 on the upper side thereof. - The
assembly 2 is disposed with a radio-frequency induction coil 5 on the outside thereof and so designed as to fedbase metal 6 of titanium or titanium alloy on the inside from under side thereof. - The
magnetic shield 4 is provided with a circlar base 11 through aseal 12 on the upper side thereof and provided with asleeve 13 on the inside of the circlar base 11, and amold chamber 14 is provided on the inside of thesleeve 13. And meltingspace 15 is formed in a part surrounded by the bottom face of themold chamber 14 and inner peripheries of theassembly 2 and themagnetic shield 4, and it is possible to replace the atomosphere in themelting space 15 with an inert gas by supplying argon through agas intake 16 provided on the circlar base 11, for example. - A
permeable mold 21 which is a ceramic shell mold is disposed in themold chamber 14, and a turbine wheelshaped molding cavity 21a in thepermeable mold 21 and themelting space 15 are connected by agate 22 formed in thepermeable mold 21 and atubular sprue 23 communicating to thegate 22. - And the
permeable mold 21 is provided with a closed feeder head 21c in the upper part thereof, and disposed with aheat insulator 24 having gas permeability on the outer surface thereof. - Further, the
mold chamber 14 is provided with anupper plate 27 through aseal 26 on the upper end thereof and thepermeable mold 21 is held with asupport 29 piercing theupper plate 27 through aseal 28, and theupper plate 27 is provided with asuction hole 27a. - Therefore, in the precision casting apparatus 1 acording to this embodiment and provided with the
assembly 2 on the inside of the radio-frequency induction coil 5 as described above, eddy currents are formed on the inside of theassembly 2 by radio frequency induction of the radio-frequency induction coil 5, and thebase metal 6 of titanium or titanium alloy is molten by an eddy current induced in the outer layer of thebase metal 6 by the eddy currents which are alternating currents. In this time themolten metal 31 of titanium or titanium alloy is slightly separated from the inner periphery of theassembly 2 by repelling force caused by currents flowing in the outermost layers of theassembly 2 and themolten metal 31 and having opposite phases each other, and a gap is formed between themolten metal 31 and theassembly 2 - Accordingly, thermal transmission from the
molten metal 31 of titanium or titanium alloy to theassembly 2 is suppressed by the formation of the gap. Thereby, a thick-walled skull which is formed in conventional furnaces of a water cooled hearth type such as an arc skull crucible furnace and so on is scarely formed, and it becomes possible to melt thebase metal 6 of titanium or titanium alloy in a better yield. And it becomes possible to regulated the temperature of themolten metal 31 of titanium or titanium alloy easily by controlling electric energy to be supplied to the radio-frequency induction coil 5. Furthermore, there is no contamination of the molten 31 practically since the ceramic crucible composed of oxides is not used. - By reducing the pressure in this state through the
suction hole 27a provided in theupper plate 27, gas existing in the molding cavity 21a and the feeder head 21c of thepermeable mold 21 is discharged in themold chamber 14 passing through thepermeable mold 21 as shown with arrows according to the difference of internal pressures between themold chamber 14 and themelting space 15, therewith themolten metal 31 of titanium or titanium alloy is sucked and cast into the molding cavity 21a through thetubular sprue 23 and thegate 22. In this time, themolten metal 31 is drawn by suction up to the feeder head 21c and is prepared for shrinkage cavity acompained with solidification shrinkage of themolten metal 31 of titanium or titanium alloy in the molding cavity 21a. - And a casting product is obtained by shakeout after the solidification of the
molten metal 31 in thepermeable mold 21. - In this embodiment, Ti-Al intermetallic compound which is light and excellent in mechanical strength at high temperature was chosen as
base metal 6 of titanium or titanium alloy, and cast into a turbine wheel for turbo charger which is 1200g in finished weight with outside diameter of 140mm. - The high-frequency generator used in this time for supplying high frequency wave to the
induction heating coil 5 is a small and simplified type comparatively having capacity of 60kW. And 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 were provided near the lower parts of respective turbine blades in total. - The
base metal 6 composed of Ti-Al intermetallic compound was fed from the under side of theassembly 2 formed with water cooledcopper segments induction heating coil 5. And thebase metal 6 was molten by forming eddy currents on the inside of theassembly 2 and inducing an eddy current in the outermost layer of thebase 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 in this time is remarkably low as compared with that of the top poured conventional precision casting (150∼50°C), it is effective for inhibiting the reaction between the
permeable mold 21 and themolten metal 31. - And by reducing the pressure at the aforementioned casting temperature by pressure of 350mm Hg or so through the
suction hole 27a, the gas in the molding cavity 21a was discharged through thepermeable mold 21 according to the difference of the internal pressures between themold chamber 14 and themelting space 15, and themolten metal 31 of Ti-Al alloy was drawn by suction in the molding cavity 21a and the feeder head 21c through thetubular sprue 23 and thegates 22. And then the turbine wheel was obtained by solidifying themolten metal 31 in the molding cavity 21a. - In this time, as the
molten metal 31 was drawn in the molding cavity 21a by vacuum casting, themolten metal 31 spreads well every nook and corner of the thinwalled turbine blade, and it was possible to obtain the turbine wheel with high accuracy in shape. - Adopting the method and the apparatus for precision casting according to this invention, it becomes possible to manufacture complicated and large-sized precision casting which has been impossible to be made substantially and the invention will contribute much to further development of the precision casting of titanium or titanium alloy. And in addition to above, it is possible to apply the method and the apparatus to presicion casting of metals or alloys of the metals having high melting points or high activity such as tungsten, molybdenum, vanadium, zirconium, lithium or the like.
- As mentioned above, the method for precision casting of titanium or titanium alloy according to this invention comprises the the step of establishing molten base metal of 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 premeable mold disposed above the molten base metal by vacuum casting. Therefore, the molten base metal is deteched from the assembly and a gap is formed between the molten metal and the assembly by repelling force caused by currents flowing in the outermost layers of the assembly and the molten metal and having opposite phases each other because the base metal is molten by an eddy current induced in the outer layer thereof by eddy currents which are alternaing currents at the time of melting the base metal of titanium or titanium alloy. And excellent effects can be obtained in that the yield rate of the base metal is improved remarkably, the control of the temperature of the molten metal is facilitated, it is possible to prevent the molten metal from the contamination and possible to obtain the precision casting of good quality because the thermal transmission from the molten metal to the assembly is suppressed and the solidified metal layer becomes not to be formed between the molten metal and the assembly.
- The precision casting apparatus for titanium or titanium alloy according to this invention 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 titanium or titanium alloy from the under side thereof, and a permeable mold for casting tha base metal molten 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 the precision castings of titanium or titanium alloy with accuracy in a better yield by enabling execution of the aforementioned method for precision casting of titanium or titanium alloy.
- The preferred embodiments of the present invention can Provide a method and an apparatus for precision casting which is possible to obtain precision castings of metals with high melting points or high activity by preventing the molten metal from the contamination in the melting, maintaining the quantity and the temperature of the molten metal required for the 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 the low temperature at the time of carring out the precision casting of titanium, titanium alloy or other metals having high melting points or high activities such as tungsten, molybdenum, vanadium, zirconium, lithium or the like.
Claims (8)
- A method for precision casting of titanium or titanium alloy which comprises :
establishing molten base metal of 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 said copper segments are insulated from each other : and
casting said molten base metal into a permeable mold disposed above the molten base metal by vacuum casting. - A method for precision casting of titanium or titanium alloy as claimed in claim 1, wherein said base metal of titanium or titanium alloy is molten in an atomosphere of an inert gas such as argon.
- A method for precision casting of titanium or titanium alloy as claimed in claim 1 or claim 2, wherein said molten base metal is cast into the permeable mold through a tubular sprue.
- A method for precision casting of titanium or titanium alloy as claimed in any one of claims 1 to 3, wherein said base metal of titanium or titanium alloy is fed continuously into the assembly formed with the water cooled copper segments from the under side of said assembly.
- A precision casting apparatus for titanium or titanium alloy comprising :
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 said copper segments are insulated from each other, and fed with base metal of titanium or titanium alloy from the under side thereof ; and
a permeable mold for casting said base metal molten by induction heating on the inside of said assembly formed with the water cooled copper segments by means of vacuum casting. - A precision casting apparatus for titanium or titanium alloy as claimed in claim 5, wherein said permeable mold is provided with a plurality of tubular sprue for conducting the molten base metal thereinto at the time of vacuum casting.
- A precision casting apparatus for titanium or titanium alloy as claimed in claim 5 or claim 6, wherein said permeable mold is provided with a closed feeder head in the upper part thereof.
- A precision casting apparatus for titanium or titanium alloy as claimed in any one of claims 5 to 7, wherein said permeable mold is a ceramic shell mold.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2124383A JP2541341B2 (en) | 1990-05-15 | 1990-05-15 | Precision casting method and precision casting apparatus for Ti and Ti alloy |
JP124383/90 | 1990-05-15 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0457502A1 true EP0457502A1 (en) | 1991-11-21 |
EP0457502B1 EP0457502B1 (en) | 1995-10-11 |
Family
ID=14884053
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19910304192 Expired - Lifetime EP0457502B1 (en) | 1990-05-15 | 1991-05-09 | Method and apparatus for precision casting |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0457502B1 (en) |
JP (1) | JP2541341B2 (en) |
DE (1) | DE69113676T2 (en) |
ES (1) | ES2080897T3 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0739667A1 (en) * | 1995-04-25 | 1996-10-30 | Daido Tokushuko Kabushiki Kaisha | Method of casting metal and apparatus therefor |
US5722481A (en) * | 1995-06-20 | 1998-03-03 | Daido Tokushuko Kabushiki Kaisha | Method for casting metal and apparatus therefor |
EP0747648B1 (en) * | 1995-05-19 | 2001-11-21 | Daido Tokushuko Kabushiki Kaisha | Levitation melting method and melting and casting method |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1696043A1 (en) * | 2005-02-25 | 2006-08-30 | WALDEMAR LINK GmbH & Co. KG | Process for casting a Titanium-alloy |
CN112916831B (en) * | 2021-01-25 | 2022-07-26 | 中国科学院金属研究所 | Preparation method of gamma-TiAl alloy with lamellar interface preferred orientation and fine lamellar characteristics |
Citations (5)
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 |
GB2035165A (en) * | 1978-10-02 | 1980-06-18 | Hitchiner Manufacturing Co | Casting in gas permeable moulds |
GB2204816A (en) * | 1987-05-07 | 1988-11-23 | Metal Casting Tech | Countergravity casting of metal with air exclusion |
DE3927998A1 (en) * | 1988-08-25 | 1990-03-01 | Reiichi Okuda | Precision casting used in mfg. dental and orthopaedic device - comprises application of inert gas pressure to melting chamber, raising inert gas pressure and prodn. of a differential pressure |
-
1990
- 1990-05-15 JP JP2124383A patent/JP2541341B2/en not_active Expired - Fee Related
-
1991
- 1991-05-09 DE DE1991613676 patent/DE69113676T2/en not_active Expired - Fee Related
- 1991-05-09 ES ES91304192T patent/ES2080897T3/en not_active Expired - Lifetime
- 1991-05-09 EP EP19910304192 patent/EP0457502B1/en not_active Expired - Lifetime
Patent Citations (5)
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 |
GB2035165A (en) * | 1978-10-02 | 1980-06-18 | Hitchiner Manufacturing Co | Casting in gas permeable moulds |
GB2204816A (en) * | 1987-05-07 | 1988-11-23 | Metal Casting Tech | Countergravity casting of metal with air exclusion |
DE3927998A1 (en) * | 1988-08-25 | 1990-03-01 | Reiichi Okuda | Precision casting used in mfg. dental and orthopaedic device - comprises application of inert gas pressure to melting chamber, raising inert gas pressure and prodn. of a differential pressure |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0739667A1 (en) * | 1995-04-25 | 1996-10-30 | Daido Tokushuko Kabushiki Kaisha | Method of casting metal and apparatus therefor |
EP0747648B1 (en) * | 1995-05-19 | 2001-11-21 | Daido Tokushuko Kabushiki Kaisha | Levitation melting method and melting and casting method |
US5722481A (en) * | 1995-06-20 | 1998-03-03 | Daido Tokushuko Kabushiki Kaisha | Method for casting metal and apparatus therefor |
Also Published As
Publication number | Publication date |
---|---|
DE69113676T2 (en) | 1996-04-18 |
ES2080897T3 (en) | 1996-02-16 |
JPH0422562A (en) | 1992-01-27 |
EP0457502B1 (en) | 1995-10-11 |
DE69113676D1 (en) | 1995-11-16 |
JP2541341B2 (en) | 1996-10-09 |
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