BACKGROUND
[0001] This disclosure generally relates to die casting, and more particularly to die casting
components with integral seals.
[0002] Gas turbine engines generally include a compressor section, a combustor section,
and a turbine section circumferentially disposed about an engine centerline axis.
At least the compressor section and the turbine section include alternating rows of
rotating rotor blades and static stator vanes. As airflow is communicated through
the gas turbine engine, the rotor blades increase the velocity of the oncoming airflow.
The stator vanes convert the velocity into pressure and prepare the airflow for the
next set of rotor blades.
[0003] Gas turbine engine components can be manufactured in a number of ways including machining
operations, forging operations or casting operations. Gas turbine engine components
are often manufactured in an investment casting process. Investment casting involves
pouring molten metal into a ceramic shell having a cavity in the shape of the component
to be cast. An abradable seal, such as a honeycomb seal, can be brazed onto the gas
path side of a gas turbine engine component to improve the seal between the gas turbine
engine component and any surrounding components.
[0004] A method of die casting a metal component with a porous reinforcing insert is disclosed
in
US 6 648 055 B1. An abradable sealing element is disclosed in
EP 1 146 204 A2. A method of producing a guide blade segment of a gas turbine engine is disclosed
in
DE 10 2006 004 090 A1.
SUMMARY
[0005] From a first aspect, the invention provides a method of die casting a component having
an integral seal, as set forth in claim 1.
[0006] The various features and advantages of this disclosure will become apparent to those
skilled in the art from the following detailed description. The drawings that accompany
the detailed description can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007]
Figure 1 illustrates a simplified cross-sectional view of a standard gas turbine engine.
Figure 2 illustrates a cross-sectional view of a portion of the gas turbine engine
depicted in Figure 1.
Figure 3 illustrates an example die casting system.
Figure 4 illustrates an example die for use with a die casting system.
Figure 5 illustrates an insert having an open cell structure that can be used with
the die of Figure 4.
Figure 6 illustrates another example die for use with the die casting system of Figure
3, which falls outside the scope of the claims.
Figure 7 illustrates a component having an integral seal that can be cast using the
die of Figure 4 or Figure 6.
DETAILED DESCRIPTION
[0008] Figure 1 illustrates a gas turbine engine 10, such as a turbofan gas turbine engine,
that is circumferentially disposed about an engine centerline (or axial centerline
axis) 12. The gas turbine engine 10 includes a fan section 14, a compressor section
15 having a low pressure compressor 16 and a high pressure compressor 18, a combustor
20, and a turbine section 21 including a high pressure turbine 22 and a low pressure
turbine 24. This disclosure can also extend to engines without a fan, and with more
or fewer sections.
[0009] As is known, air is compressed in the low pressure compressor 16 and the high pressure
compressor 18, is mixed with fuel and burned in the combustor 20, and is expanded
in the high pressure turbine 22 and the low pressure turbine 24. Rotor assemblies
26 rotate in response to the expansion, driving the low pressure and high pressure
compressors 16, 18 and the fan section 14. The compressor section 15 and the turbine
section 21 may include alternating rows of rotating rotor blades 28 and static stator
vanes 30.
[0010] It should be understood that this view is included simply to provide a basic understanding
of the sections of a gas turbine engine 10 and not to limit the disclosure. This disclosure
extends to all types of gas turbine engines 10 for all types of applications.
[0011] Figure 2 illustrates a portion of the gas turbine engine 10. In this example, the
portion depicted is the high pressure turbine 22 of the gas turbine engine 10. However,
this disclosure is not limited to applications within the high pressure turbine 22,
and could extend to other sections of a gas turbine engine 10, including but not limited
to, the low pressure turbine 24 and the compressor section 15. In addition, selected
features of the high pressure turbine 22 are shown enlarged in order to illustrated
specific details and are not shown to the scale they would be in operation.
[0012] The high pressure turbine section 22 includes a rotor assembly 26 having a plurality
of rotor blades 28 (one depicted) extending outwardly from the circumference of the
rotor assembly 26. The rotor blades 28 extend between a rim 27 of the rotor assembly
26 and a blade tip 40.
[0013] An outer casing 42 extends circumferentially about the high pressure turbine section
22 at a position radially outward from the rotor blades 28. The outer casing 42 includes
a plurality of blade outer air seals (BOAS) 44 positioned between the blade tips 40
of the rotor blades 28 and the outer casing 42. The BOAS 44 includes an integral seal
46, such as an abradable seal, that interacts with the rotor blades 28 to mitigate
gas leakage. During operation, the rotor blades 28 rotate about the engine centerline
axis 12 and at least partially wear away a portion of the integral seal 46 to seal
and mitigate gas leakage around the components within the high pressure turbine section
22. In the illustrated example, a portion 45 has been partially worn away by the rotor
blade 28.
[0014] Figure 3 illustrates a die casting system 48 for die casting a component, such as
the BOAS 44 or other seals. However, this disclosure is not limited to the die casting
of BOAS, and it should be understood that any aeronautical or non-aeronautical component
can be die cast with an integral seal according to the example methodologies of this
disclosure.
[0015] The die casting system 48 includes a reusable die 50 having a plurality of die elements
52, 54 that function to cast the component. Although two die elements 52, 54 are depicted
in Figure 3, it should be understood that the die 50 could include more or fewer die
elements, as well as other parts and configurations.
[0016] The die 50 is assembled by positioning the die elements 52, 54 together and holding
the die elements 52, 54 at a desired position via a mechanism 56. The mechanism 56
could include a clamping mechanism of appropriate hydraulic, pneumatic, electromechanical
and/or other configurations. The mechanism 56 also separates the die elements 52,
54 subsequent to casting.
[0017] The die elements 52, 54 define internal surfaces that cooperate to define a die cavity
58. A shot tube 53 is in fluid communication with the die cavity 58 via one or more
ports 60 located in the die element 52, the die element 54 or both. A shot tube plunger
62 is received within the shot tube 53 and is moveable between a retracted and injected
position (in the direction of arrow A) within the shot tube 53 by a mechanism 64.
The mechanism 64 could include a hydraulic assembly or other suitable mechanism, including,
but not limited to, pneumatic, electromechanical or any combination thereof.
[0018] The shot tube 53 is positioned to receive a molten metal from a melting unit 66,
such as a crucible, for example. The melting unit 66 may utilize any known technique
for melting an ingot of metallic material to prepare molten metal for delivery to
the shot tube 53, including but not limited to, vacuum induction melting, electron
beam melting and induction scald melting. The molten metal is melted by the melting
unit 66 at a location that is separate from the shot tube 53 and the die 50. In this
example, the melting unit 66 is positioned in relatively close proximity to the shot
tube 53 to reduce the required transfer distance between the molten metal and the
shot tube 53.
[0019] Example molten metals capable of being used to die cast a component include, but
are not limited to, nickel base super alloys, cobalt alloys, titanium alloys, high
temperature aluminum alloys, copper based alloys, iron alloys, molybdenum, tungsten,
niobium, or other refractory metals. This disclosure is not limited to use of the
disclosed alloys, and it should be understood that any high melting temperature material
may be utilized to die cast a component. As used herein, the term "high melting temperature
material" is intended to include materials having a melting temperature of approximately
1500°F (815°C) and higher.
[0020] The molten metal is transferred from the melting unit 66 to the shot tube 53 in a
known manner, such as pouring the molten metal into a pour hole 55 in the shot tube
53, for example. A sufficient amount of molten metal is communicated into the shot
tube 53 to fill the die cavity 58. The shot tube plunger 62 is actuated to inject
the molten metal under pressure from the shot tube 53 into the die cavity 58 to cast
the component. Although the casting of a single component is depicted, the die casting
system 48 could be configured to cast multiple components in a single shot.
[0021] Although not necessary, at least a portion of the example die casting system 48 can
be positioned within a vacuum chamber 70 that includes a vacuum source 72. A vacuum
is applied in the vacuum chamber 70 by the vacuum source 72 to render a vacuum die
casting process. The vacuum chamber 70 provides a non-reactive environment for the
die casting system 48 that reduces reaction, contamination or other conditions that
could detrimentally affect the quality of the cast component, such as excess porosity
of the cast component that occurs as a result of exposure to oxygen. In one example,
the vacuum chamber 70 is maintained at a pressure between 1x10
-3 Torr and 1x10
-4 Torr, although other pressures are contemplated. The actual pressure of the vacuum
chamber 70 will vary based upon the type of component being cast, among other conditions
and factors. In the illustrated example, each of the melting unit 66, the shot tube
53 and the die 50 are positioned with the vacuum chamber 70 during the die casting
process such that the melting, injecting and solidifying of the metal are all performed
under vacuum. In another example, the vacuum chamber 34 is backfilled with an inert
gas, such as Argon, for example.
[0022] The example die casting system 48 depicted in Figure 3 is illustrative only and could
include more or less sections, parts and/or components. This disclosure extends to
all forms of die casting, including but not limited to, horizontal, inclined or vertical
die casting systems.
[0023] Figure 4 illustrates an example die 150 for use with a die casting system, such as
the die casting system 48 depicted in Figure 3. In this disclosure, like reference
numerals signify like features, and reference numerals identified in multiples of
100 signify slightly modified features. Moreover, select features of one example embodiment
may be combined with selected features of other example embodiments. The die 150 may
be used to die cast a component, such as a BOAS having an integral seal, or any other
component.
[0024] The die 150 includes a die cavity 158 that is defined by a plurality of die elements
152, 154. The die cavity 158 includes a first portion 80 and a second portion 82.
The first portion 80 and the second portion 82 are openings within the die 150. Although
the example die cavity 158 is depicted as including two portions, it should be understood
that more portions may define the die cavity 158. Also, the size of shape of the first
portion 80 and the second portion 82 will vary depending upon design specific parameters
including, but not limited to, the type of component being cast.
[0025] The first portion 80 of the die cavity 158 is configured to receive an insert 84.
The insert 84 is generally sized and shaped similar to the first portion 80. In the
example embodiment, the insert 84 is a honeycomb seal made of a Nickel Alloy or other
high melting temperature material that includes an open cell structure 85 that defines
walls 87 having openings 88 therebetween, such as diamond shaped openings (See Figure
5). Other inserts having different structures are contemplated as being within the
scope of this disclosure. The insert 84 is positioned within the first portion 80
of the die cavity 158 either manually or automatically, such as with a robot, for
example.
[0026] The second portion 82 of the die cavity 158 does not include the open cell structure.
Therefore, the second portion 82 represents a void or opening within the die 150 that
is sized and shaped to correspond to the component being cast. The second portion
82 of the die cavity 158 receives molten metal M from a die casting system, such as
the die casting system 48 detailed above. Molten metal M is injected into the die
cavity 158 via the shot tube 53 and the shot tube plunger 62 and is solidified within
the die cavity 158. The molten metal M locally bonds with the insert 84 at an interface
I during solidification of the molten metal M to cast a component having an integral
seal. In other words, the component is die cast against the insert 84, thereby overcasting
the component (the portion solidified in the second portion 82) having an integral
seal (the locally bonded insert 84 located in the first portion 80) in a single operation.
[0027] Figure 6 illustrates another exemplary die 250 that may be used with a die casting
system, such as the die casting system 48 depicted above, but which falls outside
the scope of the claims. The die 250 is utilized to die cast a component having an
integral seal, such as a BOAS having a honeycomb seal, for example. Other aeronautical
and non-aeronautical components may also be cast using the die 250.
[0028] The die 250 includes a die cavity 258 defined by a plurality of die elements 252,
254. The die cavity 258 defines a first portion 280 and a second portion 282, although
more or fewer portions may be defined within the die cavity 258. Also, the size of
shape of the first portion 280 and the second portion 282 will vary depending upon
design specific parameters including, but not limited to, the type of component being
cast.
[0029] In this example, the first portion 280 of the die cavity 258 is pre-defined with
an open cell structure 285 that corresponds to a desired structure of an integral
seal. That is, the first portion 280 of the die cavity 258 is formed with design features,
such as a honeycomb, open cell structure, that are automatically form corresponding
features within a cast component once molten metal is injected into the die cavity
258, i.e., no inserts are required. The open cell structure 285 may be formed within
the first portion 280 of the die cavity 258 in any known manner. The first portion
280 defines the integral seal on the cast component.
[0030] The second portion 282 is defined without an open cell structure. Therefore, the
second portion 282 represents a void or opening within the die 250 that is sized and
shaped to correspond to the component being cast. The second portion 282 of the die
cavity 258 is made larger by a distance X to define the first portion 280, which forms
the integral seal portion of the cast component. That is, enlarging the second portion
282 of the die cavity 258 by a distance X allows the integral seal to be die cast
as a feature of the component during the die casting process.
[0031] Subsequent to melting, molten metal M is injected into the die cavity 258 and is
communicated to both the first portion 280 and the second portion 282 of the die cavity
258. The molten metal solidifies within the die cavity 258 to form a component having
an integral seal. Because the first portion 280 is defined with an open cell structure,
once solidified, the molten metal forms a component having an integral seal with a
desired structure, such as a honeycomb seal structure, for example.
[0032] Figure 7 illustrates a component 29 that may be die cast using the example dies 150,
250 described above. The component 29 includes a body portion 31 and an integral seal
33. Each of the body portion 31 and the integral seal 33 may be made from nickel based
super alloys, cobalt alloys, titanium alloys, high temperature aluminum alloys, copper
based alloys, iron alloys, molybdenum, tungsten, niobium, other refractory metals,
or any combination of such materials. Any high melting temperature material may be
utilized to die cast the component 29. In this example, the component 29 is a seal
having an integral seal 33 with an open cell structure 35, although other components
may also be cast using the example dies 150, 250, including but limited to BOAS, inner
air seals and 1-2 seals. The integral seal 33 is a honeycomb abradeable seal such
that contact with a rotor blade partially wears away the integral seal 33.
[0033] A worker of ordinary skill in the art having the benefit of this disclosure would
recognize that certain modifications could come within the scope of the disclosure.
For these reasons, the following claims should be studied to determine the true scope
and content of this disclosure.
1. Verfahren zum Druckguss einer Komponente (29) mit einer integrierten abreibbaren Wabendichtung
(33), den folgenden Schritt umfassend:
(a) Definieren eines ersten Abschnitts (80) eines Formhohlraums (158) einer Form (150),
sodass er eine offene Zellstruktur (85) beinhaltet, beinhaltend das Positionieren
eines Einsatzes (84), der die offene Zellstruktur (85) definiert, innerhalb des ersten
Abschnitts (80) des Formhohlraums (158), wobei der Einsatz (84) eine abreibbare Wabendichtung
ist, wobei der erste Abschnitt (80) eine erste Öffnung innerhalb der Form (150) ist;
(b) Definieren eines zweiten Abschnitts (82) des Formhohlraums (158) ohne die offene
Zellstruktur (85), wobei der zweite Abschnitt (82) eine zweite Öffnung innerhalb der
Form (150) ist, wobei sich der Einsatz (84) nicht in die zweite Öffnung erstreckt;
(c) Einspritzen von geschmolzenem Metall (M) in den Formhohlraum (158); und
(d) Verfestigen des geschmolzenen Metalls (M) innerhalb des Formhohlraums (158; 258),
um die Komponente (29) mit der integrierten Dichtung (33) zu bilden, wobei das geschmolzene
Metall (M), das sich in dem zweiten Abschnitt (82) verfestigt, die Komponente (29)
bildet, wobei sich das geschmolzene Metall M lokal mit dem Einsatz (84) an einer Schnittstelle
(I) während der Verfestigung des geschmolzenen Metalls M verbindet, um die Komponente
zu bilden, die die integrierte Dichtung aufweist.
2. Verfahren nach Anspruch 1, wobei Schritt (c) Folgendes beinhaltet:
Schmelzen eines Materialblocks, um das geschmolzene Metall (M) herzustellen;
Transportieren des geschmolzenen Metalls (M) in ein Einspritzrohr (53); und
Einspritzen des geschmolzenen Metalls (M) in den Formhohlraum (158) mit einem Einspritzrohrkolben
(62).
3. Verfahren nach einem vorhergehenden Anspruch, wobei die Komponente (29) eine Dichtung
ist, die eine integrierte abreibbare Wabendichtung (33) aufweist.
4. Verfahren nach einem vorhergehenden Anspruch, umfassend den folgenden Schritt:
(e) Positionieren der Form (150) innerhalb einer Vakuumkammer (70) .