HYBRID DIE CAST SYSTEM FOR FORMING A COMPONENT USABLE IN A GAS TURBINE ENGINE

Abstract

A hybrid die cast system (10) having an inner liner insert (12) that enables the configuration of a component (18) produced by the system (10) to be easily changed by changing the inner liner insert (12) without having to rework the die housing (16) is disclosed. Because the inner liner insert (12) only need be removed and replaced to change the configuration of an outer surface (18) of a component (18) produced by the system (10), the cost savings is significant in contrast with conventional systems in which the die would have to be reworked. The system (10) may also include a cooling system (20) for controlling the casting process by controlling the rate of solidification and the rate of cooling of the casting. Local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity.

Description

FIELD OF THE INVENTION

This invention is directed generally to die cast systems, and more particularly to manufacturing methods for turbine airfoils usable in turbine engines.

BACKGROUND

Die casting is traditionally limited to the casting of non-ferrous alloys because it is challenging to use the die cast process for high temperature materials such as nickel based superalloys. In the die cast process, molten metal may be forced into a mold under high pressure. This process is typically used for large volume production as there is a high initial capital investment cost associated with manufacturing the dies. Most die castings are made from non-ferrous alloys such as zinc, aluminum, and magnesium. Die casting is capable of producing dimensionally consistent parts.

Investment casting using a lost wax process is typically employed for manufacturing turbine components made from high temperature materials, such as nickel based superalloys. Investment casting is often used to form components, such as blades, vanes and ring segments. Investment casting is a versatile process that enables the casting of complex shapes that are not possible with traditional die casting. Internal cavities may be incorporated into a turbine component through use of the cores with the investment casting process.

SUMMARY OF THE INVENTION

A hybrid die cast system having an inner liner insert that enables the configuration of a component produced by the system to be easily changed by changing the inner liner insert without having to rework a die housing is disclosed. Because the inner liner insert only need be removed and replaced to change the configuration of an outer surface of a component produced by the system, the cost savings is significant in contrast with conventional systems in which the die would have to be reworked. The system may also include a die cooling system for controlling the casting process by controlling the rate of solidification and the rate of cooling of the casting. Local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity.

In at least one embodiment, the hybrid die cast system may include a die housing having one or more inner chambers and one or more inner liners positioned within the inner chamber of the die housing. The inner liner may have an inner surface defining boundaries useful to form an outer surface of a component. In at least one embodiment, the inner surface of the inner liner may be configured to form the component of a gas turbine engine. In another embodiment, the inner surface of the inner liner may be configured to form an airfoil usable in a gas turbine engine. The hybrid die cast system may include one or more casting cores positioned in the inner chamber of the die housing to create an inner cooling system within the airfoil. The hybrid die cast system may also include one or more intermediate liners positioned between the inner liner and an inner surface of the inner chamber in the die housing. The intermediate liner may be formed from one or more compliant materials allowing for differential expansion to occur.

The hybrid die cast system may also include one or more die cooling systems formed from one or more serpentine cooling channels positioned within the inner liner. The die cooling system may include one or more cooling fluid supply manifolds in fluid communication with inlets of a plurality of cooling channels and one or more cooling fluid collection manifolds in fluid communication with outlets of the plurality of cooling channels. The die cooling system may also include one or more valves for controlling flow of cooling fluids through the die cooling system. The hybrid die cast system may also include one or more die heating systems formed from one or more heating channels positioned within the die housing.

A method of forming a component of a gas turbine engine is disclosed. The method may include positioning one or more casting cores in an inner chamber of a die housing, wherein the die housing has at least one inner chamber and at least one inner liner positioned within the inner chamber of the die housing and wherein the inner liner may have an inner surface defining boundaries useful to form an outer surface of a component. The method may also include injecting molten metal into the inner chamber of the die housing defined by the inner surface of the inner liner. The method may also include controlling a rate of solidification and a rate of cooling of the casting via at least one die cooling system formed from one or more serpentine cooling channels positioned within the inner liner and including one or more cooling fluid supply manifolds in fluid communication with inlets of a plurality of cooling channels, one or more cooling fluid collection manifolds in fluid communication with outlets of the plurality of cooling channels and one or more valves for controlling flow of cooling fluids through the die cooling system.

An advantage of the hybrid die cast system is that because the inner liner insert only need be removed and replaced to change the configuration of an outer surface of a component produced by the system, a significant cost savings is captured in contrast with conventional systems in which the die would have to be reworked.

Another advantage of the hybrid die cast system is that the die cooling system and die heating system may be used to control the rate of solidification and the rate of cooling of the casting component and local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity.

Yet another advantage of the hybrid die cast system is that the die cooling system and die heating system may be used to retain molten alloy in certain locations of the casting component, especially in sections where mold fill may otherwise be difficult.

Another advantage of the hybrid die cast system is that use of the hybrid die cast system will reduce time and effort required to build a shell in a conventional casting process.

These and other embodiments are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.

FIG. 1 is a cross-sectional view of the hybrid die cast system.

FIG. 2 is a cross-sectional view of the die cooling system and heating system of the hybrid die cast system.

FIG. 3 is cross-sectional view of another embodiment of the die cooling system and heating system of the hybrid die cast system.

FIG. 4 is a perspective view of an airfoil usable in a gas turbine engine.

FIG. 5 is a cross-sectional view of the airfoil shown in FIG. 5 taken at section line 5-5 in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-5, a hybrid die cast system 10 having an inner liner insert 12 that enables the configuration of a component 14 produced by the system 10 to be easily changed by changing the inner liner insert 12 without having to rework a die housing 16 is disclosed. Because the inner liner insert 12 only need be removed and replaced to change the configuration of an outer surface 18 of a component 14 produced by the system 10, the cost savings is significant in contrast with conventional systems in which the die would have to be reworked. The system 10 may also include a die cooling system 20 for controlling the casting process by controlling the rate of solidification and the rate of cooling of the casting. Local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity.

In at least one embodiment, the hybrid die cast system 10 may include a die housing 16 having at least one inner chamber 22 and one or more inner liners 12 positioned within the inner chamber 22 in the die housing 16. The inner liner 12 may have an inner surface 24 defining boundaries useful to form an outer surface 18 of a component 14. One or more inner liners 12 may be positioned within the inner chamber 22 of the die housing 16 such that the inner liner 12 may have an inner surface 24 defining boundaries useful to form an outer surface 18 of a component 14. In at least one embodiment, the inner surface 24 of the inner liner 12 may be configured to form the component 14 of a gas turbine engine, as shown in FIGS. 4 and 5. In yet another embodiment, the inner surface 24 of the inner liner 12 may be configured to form an airfoil 28 usable in a gas turbine engine. The airfoil 28 may be formed from a generally elongated, hollow airfoil 60 having a leading edge 62 on an opposite side from a trailing edge 64 and separated by a concave pressure side 66 and a convex suction side 68. One or more casting cores 61 may be positioned in the inner chamber 22 of the die housing 16 to form one or more channels of an internal cooling system in the airfoil 28. In at least one embodiment, as shown in FIG. 1, the die housing 16 may be formed from a first die subhousing 56 and a second die subhousing 58.

In at least one embodiment, the inner liner 12 may be formed, at least in part, from one or more ceramic materials. The ceramic liner 12 may form a shell that may be used to produce features in the casting that would not be possible with conventional die casting due to pull-plane restrictions. The ceramic liner 12 may be formed in any appropriate manner, such as, but not limited to, flexible silicon technology, or an additive manufacturing process, such as, but not limited to, three dimensional printing or selective laser melting. The configuration of the inner surface 24 of the ceramic liner 12 may be changed to change the configuration of the outer surface 18 of a component 14 formed within the hybrid die cast system 10 without having to rework the die housing 16. As such, a significant cost savings is realized. In addition, the ceramic liner 12 may also provide a barrier between the molten metal used to form the component 14 within the inner chamber 22 of the liner 12, thereby preventing the molten metal from contacting the die housing 16 during the casting process.

In at least one embodiment, the hybrid die cast system 10 may include one or more intermediate liners 30 positioned between the inner liner 12 and an inner surface 32 of the inner chamber 22 in the die housing 16. The intermediate liner 30 may be formed from one or more compliant materials allowing for differential expansion to occur. The intermediate liner 30 may accommodate any dimensional mismatch between the die housing 16 and the inner liner 12. In at least one embodiment, the intermediate layer 30 may be formed from an unfired ceramic, i.e. green state.

The hybrid die cast system 10 may also include one or more die cooling systems 20 formed from one or more cooling channels 38 or one or more heating systems 36, or both, for controlling the casting process. The heating and cooling systems 20, 36 may be used to control the rate of solidification and the rate of cooling of the casting component 14. Local heating and cooling may be used to control the microstructure, enhance mold fill and reduce casting defects such as porosity. The heating and cooling systems 20, 36 may be used to retain molten alloy in certain locations of the casting component 14, especially in sections where mold fill may otherwise be difficult. The cooling system 20 may be configured to provide cooling to the hybrid die cast system 10 via embedded cooling channels 38. The cooling fluid used within the cooling system 20 may be, but is not limited to being, a gas, e.g. air or other inert gas, or a liquid, e.g. water, oil, polymer solution, molten salt, or liquid metal such as aluminum or tin. The heating and cooling systems 20, 36 may be used to form temperature gradients within the hybrid die cast system 10 to promote directional solidification.

In at least one embodiment, the die cooling system 20 may be formed from one or more serpentine cooling channels 38 positioned within the inner liner 12. The one cooling channels 28 may be positioned at an interface 40 between the liner 12 and one or more intermediate liners 30, positioned between the liner 12 and the inner surface 32 defining the inner chamber 22 in the die housing 16, positioned within the inner liner 12, positioned within the die housing 16, positioned within the intermediate liner 30, or any combination thereof. In another embodiment, the die cooling system 20 may include one or more cooling fluid supply manifolds 42 in fluid communication with inlets 44 of a plurality of cooling channels 38 and one or more cooling fluid collection manifolds 46 in fluid communication with outlets 48 of the plurality of cooling channels 38. One or more cooling circuits may be formed within the die cooling system 20. In at least one embodiment, multiple cooling circuits may be formed within the die cooling system 20. The die cooling system 20 may also include one or more valves 50 for controlling flow of cooling fluids through the die cooling system 20, and in particular, through the plurality of cooling circuits. In at least one embodiment, the die cooling system 20 may include a plurality of valves configured to control the cooling system 20 to switch the cooling fluid on and off in a manner that allows the cooling fluid to move according to the solidification location of the liquid metal. The die cooling system 20 may also include one or more chill plates 54. In at least one embodiment, the chill plate 54 may be positioned within the die housing 16.

The hybrid die cast system 10 may also include one or more die heating systems 36 formed from one or more heating channels 52 positioned within the die housing 16. The heating system 36 may include electrical resistance heating elements 54, which, in at least one embodiment, may be strategically placed induction coils 54 or other appropriate heat sources. One or more aspects of the heating system 36, such as, but not limited to the heating channels 52, may be positioned at an interface 40 between the liner 12 and one or more intermediate liners 30, positioned between the liner 12 and the inner surface 32 defining the inner chamber 22 in the die housing 16, positioned within the inner liner 12, positioned within the die housing 16, positioned within the intermediate liner 30, or any combination thereof. As shown in FIG. 3, the hybrid die cast system 10 may include the die cooling system 20 and the heating system 36 to move a thermal field, and more specifically, to achieve crystal growth through use of a plurality of circuits with the die cooling system 20 in conjunction with the heating system 36.

The hybrid die cast system 10 may be used in a number of manners. In at least one embodiment, the hybrid die cast system 10 may be used in a method of forming a component 14 of a gas turbine engine including positioning one or more casting cores 61 in at least one inner chamber 22 of a die housing 16, whereby the die housing 16 may have one or more inner chambers 22 and one or more inner liners 12 positioned within the inner chamber 22 of the die housing 16. The inner liner 12 may have an inner surface 24 defining boundaries useful to form an outer surface 26 of a component 14. The method may also include injecting molten metal into the inner chamber 22 of the die housing 16 defined by the inner surface 24 of the inner liner 12. The method may also include controlling a rate of solidification and a rate of cooling of the casting via one or more die cooling systems 20 formed from at least one serpentine cooling channel 38 positioned within the inner liner 12 and one or more cooling fluid supply manifolds 42 in fluid communication with inlets 44 of a plurality of cooling channels 38, at least one cooling fluid collection manifold 46 in fluid communication with outlets 48 of the plurality of cooling channels 38 and at least one valve 50 for controlling flow of cooling fluids through the die cooling system 20.

The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.

Claims

1. A hybrid die cast system (10), characterized in that:

a die housing (16) having at least one inner chamber (22); and

at least one inner liner (12) positioned within the at least one inner chamber (22) of the die housing (16), wherein the at least one inner liner (12) has an inner surface (24) defining boundaries useful to form an outer surface (18) of a component (18).

2. The hybrid die cast system (10) of claim 1, characterized in that the inner surface (24) of the at least one inner liner (12) may be configured to form the component (18) of a gas turbine engine.

3. The hybrid die cast system (10) of claim 1, characterized in that the inner surface (24) of the at least one inner liner (12) may be configured to form an airfoil (28) usable in a gas turbine engine.

4. The hybrid die cast system (10) of claim 1, further characterized in that at least one intermediate liner (30) positioned between the at least one inner liner (12) and an inner surface (32) of the at least one inner chamber (22) in the die housing (16).

5. The hybrid die cast system (10) of claim 4, characterized in that the intermediate liner (30) may be formed from at least one compliant material allowing for differential expansion to occur.

6. The hybrid die cast system (10) of claim 1, further characterized in that at least one casting core (61) positioned in the at least one inner chamber (22) of the die housing (16).

7. The hybrid die cast system (10) of claim 1, further characterized in that at least one die cooling system (20) formed from at least one cooling channel (38).

8. The hybrid die cast system (10) of claim 7, characterized in that the at least one die cooling system (20) is formed from at least one serpentine cooling channel (38) positioned within the at least one inner liner (12).

9. The hybrid die cast system (10) of claim 7, characterized in that the die cooling system (20) further comprises at least one cooling fluid supply manifold (42) in fluid communication with inlets (44) of a plurality of cooling channels (38) and at least one cooling fluid collection manifold (46) in fluid communication with outlets (48) of the plurality of cooling channels (38).

10. The hybrid die cast system (10) of claim 7, characterized in that the die cooling system (20) further comprises at least one valve (50) for controlling flow of cooling fluids through the die cooling system (20).

11. The hybrid die cast system (10) of claim 1, further characterized in that at least one die heating system (36) formed from at least one heating channel (52) positioned within the die housing (16).