CN101829770A - System for centrifugally casting high-activity titanium - Google Patents

Abstract

The invention relates to a system for centrifugally casting high-activity titanium. The system comprises a cold-wall sensing crucible, a power supply, a preheated second crucible and a centrifugal casting machine, wherein the cold wall sensing crucible is used for accommodating a titanium material and is provided with a plurality of sensing coils and a removable bottom plate; the power supply is used for heating the titanium material in the crucible so as to acquire molten metal; the preheated second crucible is used for receiving the molten metal when the molten metal falls from the sensing crucible after the bottom plate is removed and the power supply is turned off; and the centrifugal casting machine is used for maintaining the second crucible and accelerating the second crucible so as to centrifugally force the molten metal to enter a mould for generating a casting member.

Description

The system that is used for centrifugally casting high-activity titanium

Technical field

Embodiment described herein relates generally to the system that is used for the centrifugally casting high-activity metal.More specifically, the embodiment of this paper has described the system that is used for centrifugally casting high-activity titanium alloy and particularly titanium aluminide (titanium aluminide) alloy substantially.

Background technology

The turbogenerator designers constantly seek the new material of improvement in performance to alleviate engine weight and to obtain higher engine operating temperature.Titanium alloy (Ti alloy) and particularly titanium aluminide base alloy (TiAl alloy) perfect adaptation low temperature mechanical performance and middle elevated temperature strength and the creep-resistant property such as room temperature ductility and toughness.In view of these reasons, the TiAl alloy is expected to substitute the current nickel based super alloy that is used for making most turbine engine component.

Vacuum arc remelting process (VAR) is a kind of technology that generally is used for melting Ti alloy.Striking between the alloy that polylith during VAR is usually included in titanium alloy electrode and is placed in water jacketed copper crucible is identical (for example, electrode tip).Form molten bath and consumable electrode gradually.When obtaining abundant molten metal, can remove electrode and crucible is tilted so that metal is filled in the mould that is used for cast construction.

May there be several shortcomings in this VAR technology.The titanium electrode that is used for VAR technology maybe can cost an arm and a leg, and its reason is, the cost height of titanium base rod/titanium forging, and from qualified leftover pieces or reclaimed materials production human cost height that electrode comprised.Equally, the requirement to the prealloy electrode can make that the difficulty of making nonstandard alloy is big and expensive.And, need to adopt cold-crucible may limit the attainable degree of superheat of metal, this influences flowability then, causes being difficult to filling thin-walled mo(u)lding.In addition, the position temperature of arc strike metal is the highest, and has high-temperature gradient in molten metal.This also can influence the filling of mold and form weak thermograde in the process of solidified cast thing.

In view of the problems referred to above that the VAR technology exists, adoptable another kind of method is vacuum induction melting (VIM) when melting Ti alloy.The purpose of exploitation VIM is special alloy and the rare alloy that processing contains the active element such as titanium and aluminium, and it can not melting and casting in air.Along with the purposes of this type of alloy constantly increases, VIM is therefore more and more general.

Vacuum induction melting is usually included in that the metal charge of heating of metal in crucible is fused into till the liquid state in the crucible, and this crucible is made by insulation refractory alloyed oxide.In this technology, the solid-state titanium alloy of polylith is placed in the metal burner hearth of cooling, this metal burner hearth is made of copper usually, and it is melted in the inert environments that adopts the heat-flash source such as electric arc or plasma.The molten bath general at first forms at the inside and the end face of titanium material, and keeps solid-state near the titanium of copper burner hearth leg.This " skull " that solid-state titanium forms holds can contaminated liquid titanium metal.With reference to the U.S. Patent No. 4,654,858 of authorizing Rowe, its full-time instruction cold wall induction melting.

As mentioned above, it is many-sided adopting the reason of copper crucible the most at large in cold wall induction melting alloy with high activity.For example, produce significant thermal stress from porcelain crucible melting and casting meeting at crucible, this can cause the crucible cracking.This type of cracking can shorten crucible life and produce field trash in cast construction.In addition, high activity TiAl alloy can make porcelain crucible split and make titanium alloy be subjected to the oxygen in the oxide and the pollution of refractory alloy.Similar, if adopt graphite crucible, then titanium aluminide can fuse a large amount of carbon in the titanium alloy from crucible, thereby causes polluting.This type of pollution can cause titanium alloy loss mechanical performance.Copper can appearance the problems referred to above relevant with porcelain crucible and graphite crucible, and Here it is adopts the reason of copper crucible when where utilizing cold wall induction melting to come melting high activity metal alloy usually.

Yet, though carrying out the cold crucible melting in copper crucible can be the processing of above-mentioned alloy with high activity advantage aspect metallurgical is provided, but also there are many restrictions in it at technical elements and economic aspect, comprises owing to forming low overheat, the production loss that skull and high power requirement cause.Particularly, cold wall inductive crucible suffers heat loss when having a power failure, thereby allows the water-cooled copper sidewall slump of metal along mold.

In order to overcome the problems referred to above that vacuum induction melting exists, the technology a kind of newly developed that has adopted is by the bottom perfusion of nozzle from black furnace thorax smelting system.With reference to U.S. Patent No. 4,546,858 of authorizing Rowe and the U.S. Patent No. 5,164,097 of authorizing people such as Wang.Usually the nozzle material that adopts is copper or brass, thinks that they are the good materials of heat conductivility.Also mention and adopt graphite and heat-insulating material as nozzle material.

Having lot of advantages though adopt nozzle to compare with other common practice, is not the possibility that does not occur complex situations fully yet adopt nozzle.For example, black furnace thorax melting and be similar to the fusing that the reactive metal of titanium and so on can cause not expecting in the nozzle in bottom perfusion and condense.In addition, many crucible/nozzle systems are difficult to provide requisite flow rate of liquid control, are difficult to the corrosion of nozzle is reduced to bottom line, and are difficult to the fusing pollution is reduced to bottom line.

In order to overcome the problems referred to above that vacuum induction melting exists, the technology another kind of newly developed that has adopted is smelting in suspension, and it generally includes the metal electromagnetic suspension that the energy that utilizes induction coil makes melting.With reference to the United States Patent (USP) 5,275,229 of authorizing people such as Fishman, its full-time instruction smelting in suspension.Yet, though but both heating of metal of induced field, in the space of metal suspension in crucible that can keep again melting, in case system power supply is closed, metal will be slided and be back in the cold-crucible and cooling once more before it can be poured.This can cause the incomplete filling of mold.

Therefore, except that this type of improves, also need a kind of improved system that is used for the high activity metal of melting such as TiAl, it allows that alloy keeps fusing in filling process, but reduced the appearance of the problem relevant with conventional smelting technology.

Summary of the invention

Embodiments of the invention relate in general to the system that is used for casting eccentrically highly active titanium, and this system comprises: be used to hold the cold wall inductive crucible of titanium material, this inductive crucible has a plurality of induction coils and removable base plate; Power supply, the titanium material that is used for the heat induced crucible is to obtain molten metal; Preheated second crucible, be used for molten metal removable base plate removed and power-off after when inductive crucible falls, catch this molten metal; And centrifugal casting machine, be used to keep second crucible and make its acceleration, to force molten metal to enter mold eccentrically and to produce cast construction.

Embodiments of the invention also relate generally to the system that is used for casting eccentrically high-activity titanium, and this system comprises: be used to hold the cold wall inductive crucible of titanium material, this inductive crucible has a plurality of induction coils and removable base plate; Power supply, the titanium material that is used for the heat induced crucible is to obtain molten metal; Preheated second crucible, be used for molten metal removable base plate removed and power-off after when inductive crucible falls, catch this molten metal; Funnel is used for molten metal is transferred to second crucible from inductive crucible; And centrifugal casting machine, be used to keep second crucible and make its acceleration, to force molten metal to enter mold eccentrically and to produce cast construction.

Embodiments of the invention also relate generally to the system that is used for centrifugally casting high-activity titanium, and this system comprises: be used to hold the cold wall inductive crucible of titanium aluminide material, the base plate that this inductive crucible has a plurality of induction coils and removes slidably; Power supply, the titanium aluminide material that is used for the heat induced crucible is to obtain the titanium aluminide of fusing; Preheated second crucible, be used for the titanium aluminide of fusing removable base plate removed and power-off after when inductive crucible falls, catch the titanium aluminide of this fusing; The niobium funnel is used for the titanium aluminide of fusing is transferred to second crucible from inductive crucible; And centrifugal casting machine, be used for after the titanium aluminide of fusing falls in second crucible, keeping second crucible static about 0.5 second to about 2 seconds, make second crucible in about 1 second to about 2 seconds, accelerate to about 100rpm then, enter mold and produce cast construction with the titanium aluminide that forces fusing eccentrically to about 600rpm.

According to the following discloses content, these and other feature, aspect and advantage will become apparent to those skilled in the art.

Description of drawings

Fig. 1 is the schematic section according to an embodiment of cold wall inductive crucible of the present invention, lays metal charge in this cold wall inductive crucible;

Fig. 2 is that the base plate of this cold wall inductive crucible is removed according to the schematic section of an embodiment of cold wall inductive crucible of the present invention, and molten metal is suspended in wherein;

Fig. 3 is the schematic section according to an embodiment of centrifugal casting of the present invention system; And

Fig. 4 is the member that can cast according to the present invention---the perspective illustration of an embodiment of low-pressure turbine blade.

The specific embodiment

The embodiments described herein relates generally to and is used for that centrifugal casting becomes the system of the member of net shape with titanium aluminide alloys with high activity metal, particularly titanium alloy, although following description is not limited to this.

According to following description, as shown in Figure 1, can provideinductive crucible 10 with body 12.Body 12 can be made by any metal with good heat-conducting and electric conductivity, such as, copper forexample.Body 12 can be a water-cooled, melts in the process of heating crucible to prevent copper.More specifically, copper is usually in about 1900 (about 1038 ℃) fusing, and TiAl melts at about 2600 °F (about 1427 ℃), and the copper in the crucible can form low-melting-point eutectic with titanium.The water cooling crucible can prevent this situation.Water-cooledinlet 24 and water-cooledoutlet 26 can be used to make cooling water through being positioned body 12 a plurality ofpassages 28 circulations on every side.Though body 2 can have any desired that is used for induction melting and the shape that is fit to, in one embodiment,body 12 can totally be configured as hollowcircular cylinder.Body 12 can have a plurality ofinduction coils 14 that are positioned at around it, can utilizepower supply 21 theseinduction coils 14 of heating.As described below,coil 14 can be melted as thermal source and be placed in the metal charge in the crucible and keep its molten state.

Crucible 10 also can haveremovable base plate 16 as shown in Figure 1.Similar tocrucible 10,base plate 16 can be made by any metal with good heat-conducting and electric conductivity, and in one embodiment, can be made ofcopper.Base plate 16 can be a water-cooled also, and has a plurality ofinduction coils 14 that are positioned its below, to help fusing to be placed in the metal charge in thecrucible 10 once more and to keep its molten state.In addition,electrical insulating board 19 can encase base plate with the heat in the bottom that helps to keep crucible 10.As described below, can take multiple mode thatbase plate 16 is removed frombody 12, include but not limited to slide (as shown in Figures 2 and 3), rotation and whereabouts etc.

In use, comprise that themetal charge 18 of alloy with high activity can be placed inbody 12 inside ofcrucible 10 as shown in Figure 1.In one embodiment,metal charge 18 can comprise titanium alloy, more specifically is titanium aluminide alloys, and can be various suitable shapes, includes but not limited to the mixing shape of bulk, ingot shape, granular, tabular, Powdered and these shapes.Yet, what those skilled in the art may appreciate that is, the amount that is placed in themetal charge 18 in thecrucible 10 can be according to intended use and different, in one embodiment, the amount ofmetal charge 18 that is used for making the low-pressure turbine blade of net shape as described below is that about 1 pound (about 454 grams) are to about 3.5 pounds (about 1588 grams), and in another embodiment, this amount is about 1.25 pounds (about 567 grams) extremely about 3.3 pounds (about 1497 grams).

Incase metal charge 18 is placed in thecrucible 10, justlid 20 can be positioned the top ofbody 12, and remain on the appropriate location to guarantee crucible 10 sealings by bezel ring, 22, covering 20 in one embodiment can be by making withcrucible 10 identical materials.Can connectpower supply 21 andmetal charge 18 can melt when reaching proper temperature, this temperature is about 2700 °F to about 2835 °F (about 1480 ℃ to about 1557 ℃) in one embodiment.What those skilled in the art may appreciate that is, the electromagnetic field that induction coil produces causes the metal charge inner heat, and its reason is the current causing resistance heating in the metal charge.Along withmetal charge 18 begins fusing, themolten metal 30 of Chan Shenging becomes in thebody 12 that is suspended in crucible 10 therefrom, and this makes that as long asmolten metal 30 just can not contact with the inboard ofbody 12 to crucible 10 power supplies.This suspension ofmolten metal 30 can prevent to form skull.

In crucible 10, in the smelting metal material, method preheatingsecond crucible 32 or other the similar holding device that are fit to arbitrarily be can adopt, microwave or radiant energy are such as but not limited to.Second crucible can be made by graphite or pottery, and can randomly have metal gasket, such as, for example, the niobium liner.Second crucible 32 can help molten metal is transferred to mold, need not be lost in any overheated of the deposite metal that produced in the induction melting process in the inductive crucible 10.More specifically, whensecond crucible 32 is made by niobium,second crucible 32 can be preheated at least about 1832 °F (about 1000 ℃), and in one embodiment from about 1832 °F to about 2200 °F (1000 ℃ to about 1200 ℃), and when second crucible is made by pottery,second crucible 32 can be preheated at least about 1980 °F (about 1082 ℃), and in one embodiment from 1980 °F to about 2400 °F (1082 ℃ to about 1316 ℃).Preheating can help to prevent the thermal shock and the cracking ofsecond crucible 32, and this will allow its recycling.Then, totally as shown in Figure 3, preheatedsecond crucible 32 can be placed in thepivoted arm 34 ofcentrifugal casting machine 36 and be located ininductive crucible 10 belows.Can adopt the conventional centrifugal casting machine that is fit to arbitrarily herein, such as, for example, Linn High-Therm Titancast 700 (Germany) or SEIT Supercast (Italy).

As previously discussed,removable base plate 16 can be removed from thebody 12 ofcrucible 10 then.In Fig. 2 and embodiment shown in Figure 3, can utilize the mechanism that is fit to arbitrarily thatbase plate 16 is removed fromcrucible 10 slidably, be such as but not limited to guide rail or guider.Althoughbase plate 16 has removed, the electromagnetic field thatinduction coil 14 produces still can makemolten metal 30 remain on suspended state till further processing as shown in Figure 2 in thebody 12 ofcrucible 10.

Whenpower supply 21 is closed,molten metal 30 can be frominductive crucible 10 inniobium funnel 33 be fallen preheatedsecond crucible 32,second crucible 32 can keep sufficiently long quiescent time so thatmolten metal 30 is transferred insecond crucible 32 fully incasting machine 36, can be about 0.5 second to about 2.0 seconds this quiescent time in one embodiment.In case finish the transfer ofmolten metal 30,second crucible 32 just fast (about 1 second to about 2 seconds) accelerate at full speed, this full speed can be extremely about 600rpm of about100rpm.Casting machine 36 can forcemolten metal 30 to break away fromsecond crucible 32 eccentrically and entermold 38 throughport 40, and thisport 40 can be at least one in otch, hole, pipeline or its combination.This quick transfer fromsecond crucible 32 to mold 38 causes be less than about 5 seconds the time of contact between this two.This of short duration contact has not only significantly reduced heat loss, and help to guarantee molten metal and be used for constituting the graphite ofsecond crucible 32 or pottery between the reaction that can not expect.

Mold 38 can comprise any ceramic model casting system that inactive surfaces coating and adiabatic backing material are provided.For instance, in one embodiment,mold 38 can comprise oxidiferous face coat.As used herein, " oxide " is meant the synthetic that is selected from the group that scandium oxide, yittrium oxide, hafnium oxide, lanthanide oxide and their combination form.In addition, lanthanide oxide (being also referred to as " rare earth " synthetic) can comprise the oxide that is selected from the group that following oxide forms, and these oxides are lanthana, cerium oxide, praseodymium oxide, neodymia, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosia, holimium oxide, erbium oxide, ytterbium oxide, luteium oxide and theircombination.Mold 38 can comprise the backing that contains the refractory material that adopts the silica gel aerosol form, and this refractory material is selected from the group that aluminium oxide, zirconium silicate, silica and combination thereof are formed.

In case molten metal is transferred in themold 38 substantially, can close centrifugal casting machine 36.Can utilize conventional method that the cast construction that forms is removed frommold 38, in one embodiment, as shown in Figure 4, this cast construction can be a low-pressure turbine blade 42.Owing to adopt centrifugal casting, needblade 42 is carried out a little casting back processing.The centrifugal force thatcasting machine 36 produces guarantees the best filling ofmold 38 by the filling that improves the thin portion of mold, thereby the cast construction of net shape is provided.

In addition, owing to utilize cold wall crucible to come the smelting metal material, so the stress on the crucible is less, therefore, the possibility of crucible cracking is less.Like this, both allowed the repeated use of crucible, can make again in the cast construction field trash still less.In addition, because contacting between molten metal and second crucible is limited, has reduced molten metal and be subjected to contamination of heavy owing to crucible splits.Pollution still less can improve the mechanical performance of titanium alloy.

This written description has used the example that comprises optimal mode to come open the present invention, and makes any technical staff of this area can make and utilize the present invention.The patentable scope of the present invention is defined by the claims, and can comprise other example that those skilled in the art expect.If this type of other example is not different from the described structural detail of claim word language; perhaps they comprise that the word language with claim does not have the equivalent structure element of essential distinction, think that then this type of other example is included in the protection domain of claim.

Claims (20)

1. system that is used for casting eccentrically high-activity titanium comprises:

Be used to hold the cold wall inductive crucible of titanium material, described inductive crucible has a plurality of induction coils and removable base plate;

Power supply is used to heat the interior titanium material of described inductive crucible to obtain molten metal;

Preheated second crucible is used for after removing described removable base plate and closing described power supply it being caught when described inductive crucible falls when described molten metal; And

Centrifugal casting machine is used for keeping and makes described second crucible acceleration entering mold and generation cast construction to force described molten metal eccentrically.

2. system according to claim 1 is characterized in that, described titanium material package is drawn together titanium aluminide alloys.

3. system according to claim 1 is characterized in that, the base plate of described inductive crucible uses to be selected from by the method in the group of sliding, rotating and falling to being formed and is removed.

4. system according to claim 1 is characterized in that described cast construction comprises low-pressure turbine blade.

5. system according to claim 2 is characterized in that, the induction coil of described inductive crucible is used for described metal charge is heated to from about 1480 ℃ of extremely about 1557 ℃ temperature to obtain described molten metal.

6. system according to claim 1 is characterized in that, described molten metal becomes and is suspended in the described inductive crucible.

7. system according to claim 2, it is characterized in that when described second crucible was made of niobium, described second crucible was heated to about at least 1000 ℃ temperature, and when described second crucible was made of pottery, described second crucible was heated to about at least 1082 ℃ temperature.

8. system according to claim 1 is characterized in that:

Described centrifugal casting machine back in described molten metal falls into described second crucible kept described second crucible static about 0.5 second to about 2 seconds, and afterwards, described centrifugal casting machine makes described second crucible accelerate to about 100rpm to about 600rpm in about 1 second to about 2 seconds, produces described cast construction to force described molten metal to enter described mold eccentrically.

9. system that is used for casting eccentrically high-activity titanium comprises:

Be used to hold the cold wall inductive crucible of titanium material, described inductive crucible has a plurality of induction coils and removable base plate;

Power supply is used to heat the interior titanium material of described inductive crucible to obtain molten metal;

Preheated second crucible is used for after removing described removable base plate and closing described power supply it being caught when described inductive crucible falls when described molten metal;

Funnel is used for described molten metal is transferred to described second crucible from described inductive crucible; And

Centrifugal casting machine is used for keeping and makes described second crucible acceleration entering mold and generation cast construction to force described molten metal eccentrically.

10. system according to claim 9 is characterized in that, described titanium material package is drawn together titanium aluminide alloys.

11. system according to claim 9 is characterized in that, the base plate of described inductive crucible uses to be selected from by the method in the group of sliding, rotating and falling to being formed and is removed.

12. system according to claim 10 is characterized in that, described cast construction comprises low-pressure turbine blade.

13. system according to claim 10 is characterized in that, the induction coil of described inductive crucible is used for described metal charge is heated to from about 1480 ℃ of extremely about 1557 ℃ temperature to obtain described molten metal.

14. system according to claim 9 is characterized in that, described molten metal becomes and is suspended in the described inductive crucible.

15. system according to claim 10, it is characterized in that when described second crucible was made of niobium, described second crucible was heated to about at least 1000 ℃ temperature, and when described second crucible was made of pottery, described second crucible was heated to about at least 1082 ℃ temperature.

16. system according to claim 9 is characterized in that

Described centrifugal casting machine back in described molten metal falls into described second crucible kept described second crucible static about 0.5 second to about 2 seconds, and afterwards, described centrifugal casting machine makes described second crucible accelerate to about 100rpm to about 600rpm in about 1 second to about 2 seconds, produces described cast construction to force described molten metal to enter described mold eccentrically.

17. a system that is used for casting eccentrically high-activity titanium comprises:

Be used to hold the cold wall inductive crucible of titanium aluminide material, the base plate that described inductive crucible has a plurality of induction coils and removes slidably;

Power supply is used to heat the titanium aluminide of titanium aluminide material to obtain to melt in the described inductive crucible;

Preheated second crucible is used for after removing described removable base plate and closing described power supply it being caught when described inductive crucible falls when the titanium aluminide of described fusing;

The niobium funnel is used for the titanium aluminide of described fusing is transferred to described second crucible from described inductive crucible; And

Centrifugal casting machine, be used for after the titanium aluminide of described fusing falls in described second crucible, keeping described second crucible static about 0.5 second to about 2 seconds, and afterwards, make described second crucible in about 1 second to about 2 seconds, accelerate to about 100rpm, enter mold and produce cast construction with the titanium aluminide that forces described fusing eccentrically to about 600rpm.

18. system according to claim 17 is characterized in that, the induction coil of described inductive crucible be used for described metal charge be heated to from about 1480 ℃ to about 1557 ℃ temperature, to obtain described molten metal.

19. system according to claim 17, it is characterized in that when described second crucible was made of niobium, described second crucible was heated to about at least 1000 ℃ temperature, and when described second crucible was made of pottery, described second crucible was heated to about at least 1082 ℃ temperature.

20. system according to claim 17 is characterized in that, described cast construction comprises low-pressure turbine blade.

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