Patent Description:
Various metals, such as titanium alloys, as well as various metal alloys, exhibit superplasticity within limited temperature ranges and strain rates. Superplasticity refers to the ability of a material to develop unusually high tensile elongations with a reduced tendency toward necking - e.g., a reduction in localized deformation where large amounts of strain occur disproportionately in small, localized regions of material. Thus, while in a superplastic state, the metal or metal alloy exhibits low resistance to deformation and may be elongated with controlled thinning using a process referred to as superplastic forming. Superplastic forming (SPF) permits a sheet of such metal to be readily formed against dies to achieve desired shapes while maintaining a substantially uniform thickness in the finished part without any weak points. Vacuum superplastic forming (VSPF) is similar to SPF, except the forming process is carried out in a vacuum, using an inert gas to deform a metal workpiece while in a superplastic state.

<CIT> discloses a prior art assembly as set forth in the preambles of claims <NUM> and <NUM>.

<CIT> discloses a prior art method of manufacturing hollow articles by superplastic forming and diffusion bonding.

<CIT> discloses a prior art method for molding parts.

From one aspect, there is provided an assembly for forming multiple nacelle components as recited in claim <NUM>.

There is also provided a method for forming multiple nacelle components as recited in claim <NUM>.

While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the appended claims.

With reference to <FIG>, a nacelle <NUM> for a gas turbine engine is illustrated according to various embodiments. The nacelle <NUM> may be suitable for an aircraft and comprise an inlet <NUM>, a fan cowl <NUM> and a thrust reverser <NUM>. The fan cowl <NUM> may comprise two halves pivotally mounted to a pylon <NUM> via one or more hinges. In this regard, the fan cowl <NUM> may comprise a first fan cowl (also referred to as a right-hand (RH) fan cowl) and a second fan cowl (also referred to as a left-hand (LH) fan cowl). The nacelle <NUM> may also define a centerline A-A'. In various embodiments, an exhaust nozzle <NUM> may extend from a turbine engine mounted within the nacelle <NUM>. The nacelle <NUM> may be coupled to the pylon <NUM>, which is used to mount the nacelle <NUM> to an aircraft wing or aircraft body.

In various embodiments, the inlet <NUM> includes an outer barrel <NUM>, an inner barrel <NUM> and a noselip <NUM> that connects the outer barrel <NUM> to the inner barrel <NUM> and provides a leading edge surface to the inlet <NUM>. In various embodiments, the nacelle <NUM> further comprises one or more bulkheads, including a forward bulkhead <NUM>, extending circumferentially or near-circumferentially about an interior portion <NUM> of the noselip <NUM>. The forward bulkhead <NUM> may comprise a central member <NUM> and an outer side member <NUM> and an inner side member <NUM>. As illustrated in <FIG>, the central member <NUM> extends between the outer barrel <NUM> and the inner barrel <NUM> and is connected to the outer barrel by the outer side member <NUM> and to the inner barrel by the inner side member <NUM>. As described in further detail below, in various embodiments, the forward bulkhead <NUM>, including the central member <NUM>, the outer side member <NUM> and the inner side member <NUM>, may be fabricated by a superplastic forming (SPF) process and, more particularly, by a vacuum superplastic forming (VSPF) process.

Referring now to <FIG>, a series of SPF or VSPF steps used to deform a pair of metal blanks into a pair of forward bulkhead segments is illustrated, in accordance with various embodiments. Referring to <FIG>, a pair of metal blanks <NUM> is illustrated. In various embodiments, the pair of metal blanks <NUM> includes a first metal blank <NUM> and a second metal blank <NUM>. In various embodiments, the first metal blank <NUM> and the second metal blank <NUM> each comprise a sheet of metal capable of superplastic deformation, such as, for example, titanium alloy. Referring now to <FIG>, the first metal blank <NUM> and the second metal blank <NUM> are positioned adjacent one another. An outer periphery <NUM> of both the first metal blank <NUM> and the second metal blank <NUM>, extending about the four-sided periphery of each blank, is welded to seal the two blanks together. In various embodiments, a tube <NUM> is welded to a top portion <NUM> or some other portion of the outer periphery <NUM>. The welding of the tube <NUM> to, for example, the top portion <NUM> is configured to enable a pressurized gas to be injected into an interior space between the pair of metal blanks <NUM> following their being welded together about the outer periphery <NUM>. In various embodiments, the tube <NUM> is connected to a source <NUM> of gas. In various embodiments, the source <NUM> is configured to inject an inert gas, such as argon, into the interior space between the pair of metal blanks <NUM>. In various embodiments, the source <NUM> is a pressurized storage container, such as, for example, a bulk storage tank or bottle or the like.

Referring now to <FIG>, the pair of metal blanks <NUM> is illustrated as a pair of deformed metal blanks <NUM>, following its undergoing a SPF or VSPF process within a pair of dies having the shape of a forward bulkhead segment (see, e.g., <FIG>). As will be described more fully below, the pair of metal blanks <NUM>, following being welded together on the outer periphery <NUM> and having the tube <NUM> attached, is placed between the pair of dies, each die having a cavity with a contour in the shape of an outer surface of a forward bulkhead segment (see, e.g., <FIG>). The die set is heated to a temperature sufficient to cause the material comprising the pair of metal blanks <NUM> to achieve a superplastic state. Compressed gas is then introduced into the interior space between the pair of metal blanks <NUM>, thereby pressurizing the interior space and causing metal to be urged, superplastically, into the cavity of each of the pair of dies. The pair of deformed metal blanks <NUM> results, having a first deformed portion <NUM> and a second deformed portion <NUM>, each deformed portion having the shape of a forward bulkhead segment. In various embodiments, a VSPF process is employed to cause the deformation described above, requiring a space surrounding the pair of metal blanks <NUM> or both the pair of metal blanks <NUM> and the pair of dies be brought to vacuum conditions. Superplastic deformation (or deformation occurring in a state of superplasticity) refers, herein, to states in which fine-grained crystalline materials, such as titanium alloys, are capable of deforming substantially beyond the typical breaking points that occur at temperatures below the onset of superplasticity. For example, superplastically deformed materials tend to thin uniformly under tensile loads rather than forming a "neck" and fracturing.

Referring now to <FIG>, perspective views of a first forward bulkhead segment <NUM> and a second forward bulkhead segment <NUM> are illustrated. In various embodiments, the first forward bulkhead segment <NUM> is the first deformed portion <NUM> and the second forward bulkhead segment <NUM> is the second deformed portion <NUM>, described above with reference to <FIG>. In various embodiments, the first forward bulkhead segment <NUM> and the second forward bulkhead segment <NUM> are obtained from the pair of deformed metal blanks <NUM>, above described, by cutting away the undeformed material surrounding the first deformed portion <NUM> and the second deformed portion <NUM>. The first forward bulkhead segment <NUM> that results includes a central member <NUM>, an outer side member <NUM> and an inner side member <NUM>, similar to the central member <NUM>, the outer side member <NUM> and the inner side member <NUM> described above with reference to <FIG>. Similarly, the second forward bulkhead segment <NUM> includes a central member <NUM>, an outer side member <NUM> and an inner side member <NUM>, similar to the central member <NUM>, the outer side member <NUM> and the inner side member <NUM> described above with reference to <FIG>. In various embodiments, the first forward bulkhead segment <NUM> includes a first end <NUM> and a second end <NUM> and, similarly, the second forward bulkhead segment <NUM> includes a first end <NUM> and a second end <NUM>. Each of the ends is formed by removing the end portions that otherwise connect the central, inner side and outer side members following the deformation process. In various embodiments, the ends of adjacently positioned forward bulkhead segments are ultimately joined or assembled within the interior of the noselip using a joggle or similar joining technique.

Referring now to <FIG>, a die assembly <NUM> and a series of steps used to deform pairs of metal blanks, such as the pair of metal blanks <NUM>, using the die assembly <NUM> are illustrated, in accordance with various arrangements falling outside the wording of the claims. In various arrangements, the die assembly <NUM> includes a plurality of inner radial dies <NUM> and a plurality of outer radial dies <NUM>. In various arrangements, the plurality of inner radial dies <NUM> and the plurality of outer radial dies <NUM> are arranged in a pentagonal or circular fashion and are positioned on a base plate <NUM>. In various arrangements, both the plurality of inner radial dies <NUM> and the plurality of outer radial dies <NUM> are equal to five (<NUM>) in number, and each one of the plurality of inner radial dies <NUM> has a cross sectional shape in the form of a trapezoid, such that when assembled, the die assembly <NUM> includes a hollow interior <NUM> or lengthwise void having a pentagonal-shaped surface <NUM>. In various arrangements, both the plurality of inner radial dies <NUM> and the plurality of outer radial dies <NUM> equal N in number, and each one of the plurality of inner radial dies <NUM> has a cross sectional shape in the form of a trapezoid, such that when assembled, the die assembly <NUM> includes a hollow interior having a surface with cross section in the form of an N-polygon. In various arrangements, the die assembly <NUM> includes a hollow interior or lengthwise void having a surface with cross section in the form of a circle. In various arrangements, the hollow interior or lengthwise void of the die assembly <NUM> facilitates more effective heating of the system and less overall weight compared to a system without a hollow interior. In various arrangements, each of the plurality of inner radial dies <NUM> and each of the plurality of outer radial dies <NUM> is constructed of a graphite material. In various arrangements, the base plate <NUM> is constructed of a graphite material.

Still referring to <FIG>, the series of steps used to deform pairs of metal blanks, such as the pair of metal blanks <NUM>, using the die assembly <NUM> is described. A first step includes preparation of the pair of metal blanks <NUM>. In various arrangements, the preparation is accomplished as described above with reference to <FIG>. In various arrangements, five (<NUM>) pairs of metal blanks are prepared, one pair of metal blanks for each of the five pairs of inner and outer radial dies. A second step <NUM> includes placing the pair of metal blanks <NUM> adjacent an outer wall <NUM> of a first inner die <NUM>. A third step <NUM> includes placing an inner wall <NUM> of a first outer die <NUM> adjacent the still exposed surface of the pair of metal blanks <NUM>, such that the pair of metal blanks <NUM> becomes sandwiched between the outer wall <NUM> of the first inner die <NUM> and the inner wall <NUM> of the first outer die <NUM>. In various arrangements, the steps are repeated until each of the five (<NUM>) pairs of metal blanks is sandwiched between corresponding inner and outer walls of respective outer and inner dies. An additional step contemplates connection of tubes from each of the pairs of metal blanks to one or more sources of gas - e.g., connecting the tube <NUM> to the source <NUM> described above with reference to <FIG> - in order to pressurize the interiors of each of the pairs of metal blanks.

Referring now to <FIG>, following assemblage of the die assembly <NUM> as described above, one or more structural rings <NUM> are positioned about an outer surface <NUM> of the die assembly <NUM>. In various arrangements, the one or more structural rings <NUM> may comprise a cylindrical sleeve extending from the base plate <NUM> to the top of the die assembly <NUM>. In various arrangements, the one or more structural rings <NUM> or cylindrical sleeve is constructed using a material having a low coefficient of thermal expansion. In various arrangements, the material may comprise graphite or a carbon-carbon material, such as, for example, carbon fiber and graphite. In various arrangements, the one or more structural rings <NUM> or cylindrical sleeve serve to maintain the die assembly <NUM> in its assembled configuration upon heating, which causes thermal expansion and upon pressurization of the interiors of the pairs of metal blanks, both of which will have a tendency to urge the outer radial dies in a radially outward direction. Following installation of the one or more structural rings <NUM> or sleeve, the die assembly <NUM>, including the rings or cylindrical sleeve and base plate <NUM> are positioned within a furnace. In various arrangements, a VSPF process is employed to cause the deformation described above, requiring the space within the furnace surrounding the die assembly <NUM> in its assembled configuration to be evacuated and brought to vacuum conditions. The furnace then raises the temperature of the die assembly <NUM> and each of the pairs of metal blanks to a temperature sufficient to achieve a superplastic state. Compressed gas is then introduced into the interior space between each of the pairs of metal blanks causing metal to be urged, superplastically, into the cavities of each of the pair of dies- e.g., a radially inward facing cavity <NUM> in a radially inward facing wall <NUM> of the first outer die <NUM> and a radially outward facing cavity <NUM> in a radially outward facing wall <NUM> of the first inner die <NUM> - similar to the process described above with reference to <FIG>.

Referring now to <FIG>, following superplastic deformation of each of the pairs of metal blanks, the die assembly <NUM> is allowed to cool. The first outer die <NUM> is then removed from the die assembly <NUM>, followed by removal of a first pair of deformed metal blanks <NUM>. The first pair of deformed metal blanks <NUM> includes a first deformed portion <NUM> and a second deformed portion opposite the first deformed portion <NUM>, each deformed portion having the shape of a forward bulkhead segment. Each of the remaining outer dies is removed, followed by removal of each of the resulting pairs of deformed metal blanks. Similar to the discussion above with reference to <FIG>, the undeformed material is removed from the deformed portions in each of the five (<NUM>) pairs of deformed metal blanks, resulting in ten (<NUM>) forward bulkhead segments.

In various embodiments, a complete forward bulkhead, such as a forward bulkhead extending completely about the noselip <NUM>, described above with reference to <FIG>, comprises five (<NUM>) forward bulkhead segments. Thus, this disclosure and the configuration, arrangements and embodiments described above and below contemplate the fabrication of at least two (<NUM>) complete ship sets of forward bulkhead segments - e.g., one ship set for each of two engines - during each fabrication process, such as the fabrication process described above with reference to <FIG>. In various embodiments, fewer or greater numbers than five (<NUM>) bulkhead segments may be required to form a complete ship set, depending on the specific engine or aircraft under consideration. In such cases, die assemblies having fewer or greater numbers of sections are contemplated consistent with this disclosure - e.g., fewer or greater than the five (<NUM>) sections used in the die assembly <NUM> described above.

Referring now to <FIG>, a die assembly <NUM> used to deform pairs of metal blanks is illustrated, in accordance with various embodiments. In various embodiments, the die assembly <NUM> includes a plurality of radial dies <NUM>, including a first radial die <NUM>. One or more of the radial dies include cavities on circumferentially facing walls of the radial dies. For example, the first radial die <NUM> includes a first circumferentially facing wall <NUM> and a second circumferentially facing wall <NUM>. The first circumferentially facing wall <NUM> includes a first circumferentially facing cavity <NUM> and the second circumferentially facing wall <NUM> includes a second circumferentially facing cavity. A second radial die <NUM> includes a circumferentially facing wall <NUM> and a circumferentially facing cavity <NUM> extending into the die through the circumferentially facing wall <NUM>. A third radial die <NUM> includes a circumferentially facing wall <NUM> and a circumferentially facing cavity <NUM> extending into the die through the circumferentially facing wall <NUM>. The plurality of radial dies <NUM> is distributed in circumferential fashion (or in a circular pattern) about a base plate, with circumferentially facing walls of adjacently positioned radial dies facing one another.

In various embodiments, a series of steps used to deform pairs of metal blanks, similar to the steps above described, is employed. For example, a first step includes preparation of pairs of metal blanks. In various embodiments, the preparation is accomplished as described above with reference to <FIG>. In various embodiments, ten (<NUM>) pairs of metal blanks are prepared, one pair of metal blanks for sandwiching between pairs of the ten radial dies illustrated in <FIG>. A second step includes placing the pairs of metal blanks between the circumferentially facing walls of adjacently positioned radial dies. For example, a first pair of metal blanks <NUM> is illustrated positioned between the second radial die <NUM> and a fourth radial die <NUM>. In various embodiments, the radial dies, such as the first radial die <NUM> may be placed into position by lowering the die in an axial direction <NUM> or by translating the die toward an axial centerline A in a radial direction <NUM>. An additional step contemplates connection of tubes from each of the pairs of metal blanks to one or more sources of gas - e.g., connecting the tube <NUM> to the source <NUM> described above with reference to <FIG> - in order to pressurize the interiors of each of the pairs of metal blanks.

As described above, one or more structural rings or a cylindrical sleeve, similar to the one or more structural rings <NUM> and cylindrical sleeve described above with reference to <FIG>, is positioned about an outer surface of the die assembly <NUM>. Following installation of the one or more structural rings or cylindrical sleeve, the die assembly <NUM>, including the rings or sleeve and the base are positioned within a furnace. In various embodiments, a VSPF process is employed to cause the deformation described above, requiring the space within the furnace surrounding the die assembly <NUM> in its assembled configuration to be evacuated and brought to vacuum conditions. The furnace then raises the temperature of the die assembly and each of the pairs of metal blanks to a temperature sufficient to achieve a superplastic state. Compressed gas is then introduced into the interior space between each of the pairs of metal blanks causing metal to be urged, superplastically, into the cavities of each of the pair of dies, similar to the process described with reference to <FIG>.

Following superplastic deformation of each of the pairs of metal blanks, the die assembly <NUM> is allowed to cool and then disassembled. In various embodiments, one or more adjacently positioned radial dies may utilize dummy blanks positioned between pairs of opposing circumferentially facing walls to aid in disassembly of the die assembly <NUM> - e.g., to prevent the assembly from locking itself together following deformation of the metal blanks into the circumferentially facing cavities. In various embodiments, a dummy blank may comprise one of the pairs of metal blanks that is not pressurized during the superplastic forming process. The embodiments illustrated in <FIG> are capable of producing up to twenty (<NUM>) forward bulkhead segments during each superplastic forming process. In various embodiments, fewer or greater numbers of radial dies may be employed than the ten (<NUM>) radial dies illustrated in <FIG>.

Referring now to <FIG>, a die assembly <NUM> used to deform pairs of metal blanks is illustrated. In various embodiments, the die assembly <NUM> includes a plurality of radial dies <NUM>, including a first radial die <NUM>. The die assembly <NUM> shares many similarities in construction, assembly, operation and disassembly with the die assembly <NUM>, described above with reference to <FIG>, and those similarities are not repeated here. Similar to the embodiments above described, one or more structural rings or a cylindrical sleeve, such as the structural rings <NUM> and cylindrical sleeve described above with reference to <FIG>, is positioned about an outer surface of the die assembly <NUM> prior to heating. One dissimilarity is, however, the die assembly <NUM> includes one or more radial dies that do not include circumferentially facing cavities extending into the radial die through its corresponding circumferentially facing walls. For example, referring to <FIG>, a second radial die <NUM> is positioned radially opposite a third radial die <NUM>. The second radial die <NUM> includes a first circumferentially facing wall <NUM> and a second circumferentially facing wall <NUM>. As illustrated, both the first circumferentially facing wall <NUM> and the second circumferentially facing wall <NUM> are flat and include no cavity. The same feature applies to the circumferentially facing walls on the third radial die <NUM>. Employing one or more radial dies with one or both of the circumferentially facing walls being flat facilitates tailoring the number of forward bulkhead segments that are produced during each superplastic forming process. For example, the number of forward bulkhead segments produced using the die assembly <NUM> illustrated in <FIG> is fifteen (<NUM>), providing three (<NUM>) complete ship sets of five (<NUM>) forward bulkhead segments per ship set. Employing one or more radial dies with one or both of the circumferentially facing walls being flat may also facilitate disassembly of the die assembly following the superplastic forming process.

Claim 1:
An assembly (<NUM>; <NUM>) for forming multiple nacelle components (<NUM>), comprising:
a plurality of dies (<NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>) arranged about a central axis (A),
a first one (<NUM>; <NUM>; <NUM>) of the plurality of dies (<NUM>... <NUM>) having a first wall (<NUM>, <NUM>) and a first cavity (<NUM>; <NUM>) extending through the first wall (<NUM>, <NUM>) and
a second one (<NUM>; <NUM>) of the plurality of dies (<NUM>...<NUM>) having a second wall (<NUM>; <NUM>) and a second cavity (<NUM>) extending through the second wall (<NUM>; <NUM>),
wherein the first wall (<NUM>, <NUM>) and the second wall (<NUM>; <NUM>) are configured to sandwich a pair of metal blanks (<NUM>) therebetween,
characterised in that
the first one (<NUM>; <NUM>; <NUM>) of the plurality of dies (<NUM>, <NUM>, <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>) is a first radial die (<NUM>; <NUM>; <NUM>) configured for arrangement within a circular pattern and wherein the first wall (<NUM>; <NUM>) is a first circumferentially facing wall (<NUM>; <NUM>).