Patent Description:
A modern aircraft propulsion system for an airplane such as a commercial airliner includes a nacelle for housing a gas turbine engine. The nacelle typically includes an inlet lip (e.g., a nose lip) at an upstream end of the nacelle. This inlet lip is provided to form an inlet for directing incoming air into the gas turbine engine. The inlet lip has an annular body, which is preferably formed from a single sheet of material. While various methods are known in the art for forming an inlet lip, there is still room in the art for improvement.

<CIT> discloses a method and apparatus for forming an annular part comprising the steps of forming a conical or frusto-conical preform with at least one open end, initiating an actuation means to cause relative coaxial movement only between a punch, a clamping means and a gripping means thereby clamping a large diameter end of the preform in the clamping means and gripping a second small diameter end of the preform in the gripping means and inserting the punch in an axial direction into the large diameter open end of the preform until the external surface of the punch engages the internal surface of the preform, causing relative co-axial movement between the gripping means and the punch so that the portion of the wall of the preform between the punch and the gripping means is formed over the leading edge of the punch.

According to an aspect of the present invention, a method is provided for forming an annular object in accordance with claim <NUM>.

The die clamp angle may be less than the preform angle.

The die clamp angle may be between fifteen degrees and twenty-five degrees.

The preform angle may be between twenty-five degrees and forty degrees.

The external die assembly may include an inner clamp member and an outer clamp member. The frustoconical preform may be clamped between an outer surface of the inner clamp member and an inner surface of the outer clamp member. The outer surface of the inner clamp member may be angularly offset from the axis by an external die angle that is different that the die clamp angle.

The external die angle may be equal to the preform angle.

The frustoconical preform may be configured from or otherwise include metal.

The annular object may be configured as or otherwise include an inlet lip of an aircraft propulsion system nacelle.

The method may also include a step of annealing the externally drawn body following the translating of the die assembly.

The die clamp angle may be less than the external die angle.

The surface of the external die assembly may be an outer surface of the inner clamp member.

<FIG> illustrates an assembly <NUM> for forming an annular object. An example of the annular object is an inlet structure or an inlet lip of the inlet structure of a nacelle for an aircraft propulsion system, an exemplary embodiment of which is described below in further detail with respect to <FIG>. The present disclosure, however, is not limited to the foregoing exemplary annular object configuration nor to aircraft propulsion system applications.

The formation assembly <NUM> of <FIG> includes a punch <NUM>, an external die assembly <NUM> and an internal die assembly <NUM>. The formation assembly <NUM> may also include an actuation system configured to move (e.g., translate) one or more of the formation assembly components <NUM>, <NUM>, <NUM> along an axis <NUM>; e.g., an axial centerline of the formation assembly <NUM> and/or the annular object to be formed.

The punch <NUM> is configured as a tubular body. The punch <NUM> of <FIG>, for example, extends circumferentially about (e.g., completely around) the axis <NUM> so as to form a full hoop punch body. The punch <NUM> extends axially along the axis <NUM> from a punch first (e.g., base) end <NUM> to a punch second (e.g., distal) end <NUM>. The punch <NUM> extends radially between a (e.g., tubular) punch outer surface <NUM> and a (e.g., tubular) punch inner surface <NUM>. The punch inner surface <NUM> forms a punch bore <NUM> in the punch <NUM>, which punch bore <NUM> extends axially along the axis <NUM> at least partially into or through the punch <NUM> from the punch second end <NUM> towards or to the punch first end <NUM>.

The punch outer and inner surfaces <NUM> and <NUM> may meet and may be joined together at a (e.g., annular) blunt, curved and/or otherwise eased edge <NUM> of the punch <NUM> at the punch second end <NUM>. The punch inner surface <NUM> and the punch outer surface <NUM> may each be shaped to substantially follow a finished geometry of the annular object to be formed. The punch outer and inner surfaces <NUM> and <NUM> of <FIG> are shaped such that a radial width <NUM> of at least a portion (e.g., axial length), or an entirety of, a sidewall <NUM> of the punch <NUM> radially tapers as the punch <NUM> extends axially along the axis <NUM> to the punch second end <NUM>.

Referring to <FIG>, the external die assembly <NUM> includes an inner clamp member <NUM> and an outer clamp member <NUM>.

The inner clamp member <NUM> is configured as an annular body with a base <NUM> and a flange <NUM>; e.g., an annular rim. The inner clamp member <NUM> of <FIG>, for example, extends circumferentially about (e.g., completely around) the axis <NUM> so as to form a full hoop inner clamp member body. The inner clamp member <NUM> extends axially along the axis <NUM> from an inner clamp member first end <NUM> to an inner clamp member second end <NUM>. The base <NUM> of the inner clamp member <NUM> extends radially between an inner clamp member inner surface <NUM> and an inner clamp member outer surface <NUM>. The inner clamp member outer surface <NUM> of <FIG> has a frustoconical geometry. The inner clamp member outer surface <NUM> of <FIG>, for example, tapers radially inward as that surface <NUM> extends axially along the axis <NUM> to the inner clamp member second end <NUM>.

The inner clamp member outer surface <NUM> is angularly offset from the axis <NUM> by an inner clamp member angle <NUM>; e.g., an external die angle. This inner clamp member angle <NUM> may be an acute angle. The inner clamp member angle <NUM>, for example, may be greater than (or equal to) twenty-five degrees (<NUM>°) and less than (or equal to) forty degrees (<NUM>°); e.g., the angle <NUM> may be equal to thirty degrees (<NUM>°).

The flange <NUM> is located at the inner clamp member first end <NUM>. The flange <NUM> projects radially out from the base <NUM> and may be axially adjacent an edge of the inner clamp member outer surface <NUM>.

The outer clamp member <NUM> is configured as an annular body. The outer clamp member <NUM> of <FIG>, for example, extends circumferentially about (e.g., completely around) the axis <NUM> so as to form a full hoop outer clamp member body. The outer clamp member <NUM> extends axially along the axis <NUM> from an outer clamp member first end <NUM> to an outer clamp member second end <NUM>. The outer clamp member <NUM> extends radially between an outer clamp member inner surface <NUM> and an outer clamp member outer surface <NUM>. The outer clamp member inner surface <NUM> of <FIG> has a frustoconical geometry. The outer clamp member inner surface <NUM> is shaped and dimensioned to compliment (e.g., substantially mirror) the geometry of the inner clamp member outer surface <NUM>. The outer clamp member inner surface <NUM> may thereby engage the inner clamp member outer surface <NUM> as described below in further detail.

Referring to <FIG>, the internal die assembly <NUM> includes an internal die clamp <NUM> and an internal die <NUM>.

The internal die clamp <NUM> extends axially along the axis <NUM> from a die clamp first end <NUM> to a die clamp second end <NUM>. The internal die clamp <NUM> extends radially outward to a die clamp outer surface <NUM>. This die clamp outer surface <NUM> extends circumferentially about (e.g., completely around) the axis <NUM>. The die clamp outer surface <NUM> of <FIG> has a frustoconical geometry. The die clamp outer surface <NUM> of <FIG>, for example, tapers radially inward as that surface <NUM> extends axially along the axis <NUM> from the die clamp first end <NUM> to the die clamp second end <NUM>.

The die clamp outer surface <NUM> is angularly offset from the axis <NUM> by a die clamp angle <NUM>. This die clamp angle <NUM> may be an acute angle. The die clamp angle <NUM> is different (e.g., less) than the inner clamp member angle <NUM> (see <FIG>). The die clamp angle <NUM>, for example, may be greater than (or equal to) fifteen degrees (<NUM>°) and less than (or equal to) twenty-five degrees (<NUM>°); e.g., the angle <NUM> may be equal to twenty degrees (<NUM>°).

The internal die <NUM> may have a generally cup-shaped body; e.g., a body with a generally U or V shaped cross-sectional geometry. The internal die <NUM> of <FIG>, for example, includes a tubular rim <NUM> and a base <NUM>; e.g., an end cap / base plate.

The tubular rim <NUM> extends circumferentially about (e.g., completely around) the axis <NUM>. The tubular rim <NUM> extends axially along the axis <NUM> from an internal die first end <NUM> to the base <NUM>, which is disposed at an internal die second end <NUM>. The tubular rim <NUM> extends radially between an internal die outer surface <NUM> and an internal die inner surface <NUM>. The internal die inner surface <NUM> forms an aperture <NUM> (e.g., an indentation, pocket, etc.) in the internal die <NUM>, which aperture <NUM> extends (e.g., partially) into the internal die <NUM> from the internal die first end <NUM> to the base <NUM>. The internal die inner surface <NUM> of <FIG> has a frustoconical geometry. The internal die inner surface <NUM> is shaped and dimensioned to compliment (e.g., substantially mirror) the geometry of the die clamp outer surface <NUM>. The internal die inner surface <NUM> may thereby engage the die clamp outer surface <NUM> as described below in further detail.

The actuation system of <FIG> includes one or more actuators <NUM>-<NUM>; e.g., linear actuators. Each of these actuators <NUM>-<NUM> is configured to hold and/or axially translate a respective one of the formation assembly components <NUM>, <NUM>, <NUM>, <NUM>, <NUM> along the axis <NUM>. Each actuator <NUM>-<NUM> may by hydraulically, pneumatically and/or electromechanically driven.

<FIG> is a flow diagram of a method <NUM> for forming the annular object. This method <NUM> is described below with reference to the formation assembly <NUM> of <FIG>. However, the method <NUM> is not limited to using the exemplary formation assembly described above.

In step <NUM>, a frustoconical preform <NUM> is provided as shown, for example, in <FIG>. This frustoconical preform <NUM> may be constructed from sheet material. The frustoconical preform <NUM>, for example, may be constructed from a sheet of metal; e.g., sheet metal. Examples of the metal include, but are not limited to, aluminum (Al), titanium (Ti), or an alloy one or more of the foregoing metals.

The frustoconical preform <NUM> of <FIG> is configured as a tubular body. The frustoconical preform <NUM> of <FIG>, for example, extends circumferentially about (e.g., completely around) the axis <NUM> so as to form a full hoop preform body. The frustoconical preform <NUM> extends axially along the axis <NUM> from a preform first end <NUM> to a preform second end <NUM>. The frustoconical preform <NUM> extends radially between a preform outer surface <NUM> and a preform inner surface <NUM>. The preform inner surface <NUM> forms a preform bore <NUM> in the frustoconical preform <NUM>, which preform bore <NUM> extends axially along the axis <NUM> through the frustoconical preform <NUM> from the preform first end <NUM> to the preform second end <NUM>.

The frustoconical preform <NUM> and its surfaces <NUM> and <NUM> taper radially inwards as each of those elements <NUM>, <NUM>, <NUM> extends from the preform first end <NUM> to the preform second end <NUM>. Thus, a diameter <NUM> of the frustoconical preform <NUM> at the preform first end <NUM> is greater than a diameter <NUM> of the frustoconical preform <NUM> at the preform second end <NUM>.

One or more or each preform element <NUM>, <NUM>, <NUM> may be angularly offset from the axis <NUM> by a preform angle <NUM>. This preform angle <NUM> may be an acute angle. The preform angle <NUM> may be equal to the inner clamp member angle <NUM> (see <FIG>); e.g., the external die angle. The preform angle <NUM> is different (e.g., greater) than the die clamp angle <NUM> (see <FIG>). The preform angle <NUM>, for example, may be greater than (or equal to) twenty-five degrees (<NUM>°) and less than (or equal to) forty degrees (<NUM>°); e.g., the angle <NUM> may be equal to thirty degrees (<NUM>°).

In step <NUM>, the frustoconical preform <NUM> is clamped with (e.g., by) the external die assembly <NUM> as shown, for example, in <FIG>. A portion of the frustoconical preform <NUM> at (e.g., on, adjacent or proximate) the preform first end <NUM>, for example, is clamped between the inner clamp member outer surface <NUM> and the outer clamp member inner surface <NUM>. More particularly, the base <NUM> of the inner clamp member <NUM> may be inserted into the preform bore <NUM> such that the inner clamp member outer surface <NUM> radially engages (e.g., contacts) the preform inner surface <NUM> at the preform first end <NUM>. The outer clamp member <NUM> may then be translated axially along the axis <NUM> until the outer clamp member inner surface <NUM> radially engages (e.g., contacts) the preform outer surface <NUM> at the preform first end <NUM>. The frustoconical preform <NUM> may thereby be clamped radially between the clamp members <NUM> and <NUM>.

In step <NUM>, the frustoconical preform <NUM> is externally drawn to provide an externally drawn object <NUM> (see <FIG>) as shown, for example, in the sequence of <FIG> and <FIG>. The external die assembly <NUM>, which is clamped onto the frustoconical preform <NUM>, is translated axially along the axis <NUM> to draw the frustoconical preform <NUM> onto the punch outer surface <NUM> and the die clamp outer surface <NUM>. The external die assembly <NUM>, in other words, pulls the frustoconical preform <NUM> over and shapes the frustoconical preform <NUM> to the punch outer surface <NUM> and the die clamp outer surface <NUM>. The portion of the frustoconical preform <NUM> drawn onto / over the punch outer surface <NUM> may substantially take the shape and dimensions of an outer portion of the finished annular object. The portion of the frustoconical preform <NUM> drawn onto / over the die clamp outer surface <NUM> is reshaped to increase the diameter <NUM> at the second end <NUM>; e.g., the diameter <NUM> at the stage in <FIG> is greater than the diameter <NUM> at the stage in <FIG>.

The drawing of the frustoconical preform <NUM> onto the punch <NUM> may be performed simultaneously with the drawing of the frustoconical preform <NUM> onto the die clamp <NUM>. The method <NUM> of the present disclosure, however, is not limited to such a simultaneous drawing. For example, in other embodiments, the frustoconical preform <NUM> may be partially or completely drawn onto the die clamp <NUM> before the drawing of the frustoconical preform <NUM> onto the punch <NUM>, or vice versa.

In some embodiments, the translation of the external die assembly <NUM> may partially draw the frustoconical preform <NUM> onto the die clamp outer surface <NUM>. The drawing of the frustoconical preform <NUM> onto the die clamp outer surface <NUM> may subsequently be completed by mating the internal die <NUM> with the internal die clamp <NUM>.

In step <NUM>, the internal die <NUM> is mated with the internal die clamp <NUM> to clamp the externally drawn object <NUM> as shown, for example, in <FIG>. A portion of the externally drawn object <NUM> at (e.g., on, adjacent or proximate) the preform second end <NUM>, for example, is clamped between the die clamp outer surface <NUM> and the internal die inner surface <NUM>. More particularly, the internal die <NUM> may be translated axially along the axis <NUM> until the internal die inner surface <NUM> radially engages (e.g., contacts) the outer surface <NUM> at the second end <NUM>. The externally drawn object <NUM> may thereby be clamped radially between the internal die clamp <NUM> and the internal die <NUM>.

In step <NUM>, the externally drawn object <NUM> is at least partially (or completely) internally drawn to provide an annular body <NUM> (see <FIG>) as shown, for example, in the sequence of <FIG> and <FIG>. For example, the internal die assembly <NUM>, which is clamped onto the externally drawn object <NUM>, is translated axially along the axis <NUM> into the punch bore <NUM> to at least partially (or completely) draw the externally drawn object <NUM> against the punch inner surface <NUM>. The internal die assembly <NUM>, in other words, pulls the externally drawn object <NUM> along and shapes the externally drawn object <NUM> to the punch inner surface <NUM>. The portion of the externally drawn object <NUM> drawn against the punch inner surface <NUM> may substantially take the shape and dimensions of an inner portion of the finished annular object.

It is worth noting, by increasing the diameter <NUM> (see <FIG>) at the second end <NUM> in step <NUM>, the distance of radial movement of the object's material is reduced when pressed against the punch inner surface <NUM>. This in turn may reduce defects in the object's material such as, but not limited to, cracks and wrinkles. In addition, the internal drawing may be performed without intermediate annealing step(s), or with a reduced number of intermediate annealing step(s).

In step <NUM>, the annular body <NUM> is heat treated. This heat treatment may be preformed while the annular body <NUM> is configured with the formation assembly <NUM>. Alternatively, the heat treatment may be performed after the annular body <NUM> is removed from the formation assembly <NUM>.

In step <NUM>, the annular body <NUM> is trimmed to provide the finished annular object. For example, portions (e.g., see <NUM> and <NUM> in <FIG>) of the annular body <NUM> which were used for clamping may be cut off.

The method <NUM>, of course, may include one or more additional steps other than those discussed above. For example, the internal drawing of the externally drawn object <NUM> may be performed iteratively and, between iterations, the object's material may be annealed or otherwise heat treated. In another example, one or more additional finishing operations (e.g., polishing, etc.) may be performed before or after the trimming step <NUM>. The method <NUM> of the present disclosure, therefore, is not limited to the exemplary steps nor particular sequence of performing the exemplary steps described above.

<FIG> illustrates an aircraft propulsion system <NUM> for an aircraft such as, but not limited to, a commercial airliner or a cargo plane. The propulsion system <NUM> includes a nacelle <NUM> and a gas turbine engine. This gas turbine engine may be configured as a highbypass turbofan engine. Alternatively, the gas turbine engine may be configured as any other type of gas turbine engine capable of propelling the aircraft during flight.

The nacelle <NUM> is configured to house and provide an aerodynamic cover for the gas turbine engine. An outer nacelle structure <NUM> of the nacelle <NUM> extends along an axial centerline <NUM> of the gas turbine engine between a nacelle forward end <NUM> and a nacelle aft end <NUM>, which centerline <NUM> may be coaxial with the axis <NUM>. The nacelle structure <NUM> of <FIG> includes a nacelle inlet structure <NUM>, one or more fan cowls <NUM> (one such cowl visible in <FIG>) and a nacelle aft structure <NUM>, which may be configured as part of or include a thrust reverser system <NUM>. The annular object formed with the assembly <NUM> of <FIG> and/or the method <NUM> of <FIG> may be configured as a portion of, an entirety of or otherwise include the inlet structure <NUM>. The annular object, for example, may be configured as an inlet lip <NUM> (e.g., a nose lip) of the inlet structure <NUM>.

Claim 1:
A method for forming an annular object, comprising:
providing a frustoconical preform (<NUM>) extending axially along an axis (<NUM>), wherein a sidewall of the frustoconical preform (<NUM>) is angularly offset from the axis (<NUM>) by a preform angle (<NUM>);
clamping the frustoconical preform (<NUM>) with an external die assembly (<NUM>), wherein a surface of the external die assembly (<NUM>) abutted against the frustoconical preform (<NUM>) is angularly offset from the axis (<NUM>) by an external die angle (<NUM>);
translating the external die assembly (<NUM>) axially along the axis (<NUM>) to externally draw the frustoconical preform (<NUM>) over an outer surface (<NUM>) of a punch (<NUM>) and an outer surface (<NUM>) of a die clamp (<NUM>) to provide an externally drawn body (<NUM>), wherein the outer surface (<NUM>) of the die clamp (<NUM>) is angularly offset from the axis (<NUM>) by a die clamp angle (<NUM>) that is different than the preform angle (<NUM>), and the die clamp angle (<NUM>) is different than the external die angle (<NUM>);
mating a die (<NUM>) with the die clamp (<NUM>) to provide a die assembly (<NUM>), wherein the externally drawn body (<NUM>) is clamped radially between the die (<NUM>) and the die clamp (<NUM>); and
translating the die assembly (<NUM>) axially along the axis (<NUM>) and into a bore (<NUM>) of the punch (<NUM>) to at least partially internally draw the externally drawn body (<NUM>) against an inner surface (<NUM>) of the punch (<NUM>).