Patent Application
20180200799
This application is based upon and claims the benefit of priority from British Patent Application No. 1700614.9 filed 13 Jan. 2017, the entire contents of which are incorporated herein.
The present disclosure concerns a method of manufacturing a component and in particular, although not exclusively, a method of forming a component using hot isostatic pressing.
It is known to form manufacture components from powdered materials, such as powdered metals or ceramics. A number of methods are available to form solid components from powders, and the chosen method depends upon the required properties of the component and the available budget. For example, sintering is a cheaper and simpler method of forming a component from powder, whilst hot isostatic pressing (HIP) is more expensive and complex but forms a component having improved mechanical properties when compared to the same component formed by sintering.
Powder forming components has inherent difficulties, particularly in relation to producing net-shape or near-net-shape conditions of supply (COS). As the arrangement and conglomeration of the powder can sometimes be non-uniform, some parts of the component may be denser than others or may reduce in volume to a greater extent than others during forming. This can mean that further machining operations may be required to put the codsamponent in net-shape or near-net-shape COS, which can be an inefficient use of time, money, and resources.
GB2412949 provides a turbine stator casing which comprises a housing and fastening hooks projecting from an inner face of the housing for fastening nozzle or guide vanes thereto. The housing is made of a first alloy by hot isostatic compression, using a metal powder, and the fastening hooks are made of second alloy, which is more refractory than the first alloy, and are secured to the housing by diffusion welding during the hot isostatic compression. The second alloy may comprise nickel and/or cobalt. The application also provides a method of manufacturing the turbine stator casing using a destroyable mould.
US2004/06956 describes filtering candles comprising a sintered filtering tube and a cast iron collar which is connected thereto. The collar comprises an annular collar wall which is oriented towards the filtering tube from the neck. Said wall comprises at least one recess which is arranged in a perpendicular manner and at an angle in relation to a plane which is perpendicular to the axis of the filtering tube.
U.S. Pat. No. 4,097,276 describes a turbine wheel having a plurality of blades radiating from a central hub which is manufactured by assembling a plurality of preformed ceramic or superalloy blades into a ring with foot portions on the blades projecting into the central region of the assembly, filling such central region with powdered ceramic material, such as silicon carbide, or a superalloy material, heating and isostatically pressing at least the central region to compact the powdered material around the foot portions into a unitary hub.
U.S. Pat. No. 4,855,103 describes a method of manufacturing metal products from a powder which is received in a mould cavity formed by a gas-tight casing and is isostatically hot pressed in the casing to form a monolithic body. A body of graphite, hexagonal boron nitride, or another similar ceramic material is provided as a core in the mould cavity, and after the isostatic hot pressing this core is removed from the produced monolithic body by blasting.
The present disclosure seeks to provide an improved method for forming components from a powder.
The present disclosure provides a method of manufacturing a component according to the appended claims.
Described herein is a method of manufacturing a component having a main part and a projecting feature, the method comprising providing a shaped void corresponding to the component, locating a pre-formed element in a feature region of the shaped void corresponding to the projecting feature; placing a powder into the shaped void, and forming the element and the powder into a conglomerated the component such that the element creates at least a part of the projecting feature.
Further described is a method of manufacturing a component having a main part and a projecting feature, the method comprising: providing a shaped void corresponding to the component within a canister, the shaped void further comprising a recess to provide a feature region for receiving a pre-formed element to provide the projecting feature; locating the pre-formed element in the feature region of the shaped void which corresponds to the projecting feature such that the pre-formed element only partially fills the feature region such that it can be surrounded by powder within the feature region; locating powder within the shaped void and around the pre-formed element within the feature region; and forming the element and the powder into the component such that the element creates at least a part of the projecting feature.
The shaped void may comprise an annular gap between a first and second canisters or parts. The recess may have a first thickness corresponding to the projecting feature, and a second region having a second thickness less than the first thickness corresponding to the main part.
The element and the powder may be formed into the component using a hot isostatic pressing process. The element and powder may be formed into the component using a sintering process, or a cold isostatic pressing process.
The element and powder may be formed into a conglomerated or amalgamated component. Following the forming, the element and powder may be combined such that any interface between the portion of the component formed by the element and the powder are indistinguishable.
The element may be formed of the same or substantially the same material as the powder. The element may be a solid mass of material. The element may also be known as an insert. It should be understood that “solid” in the context of the present disclosure may mean a non-particulate solid. The element may be a contiguous mass of material. The powder may be a metal powder, a metal alloy powder, a ceramic powder, or a polymeric powder. The material of the element may be non-soluble or may have equal solubility to the powder or the material of the powder.
The element may be shaped such that a depth of the powder between the element and a wall of the shaped void is substantially constant.
The shaped void may comprise a region having a first thickness corresponding to the projecting feature, and a second region having a second thickness less than the first thickness corresponding to the main part. The shaped void may comprise an annular gap between first and second canisters or parts. The shaped void may further comprise a recess comprising the feature region for receiving the element and for forming the projecting feature. The projecting feature may be a boss or duct of the component.
The boss or duct may comprise a bore from an interior to an exterior of the component. The element may comprise a bore cavity which forms a part of the bore. The bore cavity may partially form a bore. The method may further comprise completing a partially formed bore through the component with a further machining operation.
The component may be an aerospace component. An aerospace component may be a component for forming a part of an aircraft, such as a fixed wing aircraft or a rotary aircraft, such as a helicopter.
The component may be an engine casing, such as a gas turbine engine casing. The element may form a portion of a boss or duct of the engine casing.
The method may further comprise forming the element by hot isostatic pressing. The element may also be formed by sintering, machining, casting, or extrusion.
The element may supported in the feature region by one or more support members. The or each support member may be in contact with a wall of the shaped void. The or each support member may be elongate, such as a pins or a leg. The or each support member may be formed as part of the element, or may be a separate part. The or each support member may be formed of the same material as the element or the powder.
The component may have a plurality of projecting features and a pre-formed element may be located in each of a plurality of feature regions of the shaped void corresponding to the plurality of projecting features.
The method may be a method of reducing local deformations or deviations in reduction in volume during the manufacture of a component by hot isostatic pressing.
The present disclosure may also provide an apparatus for forming a component comprising a shaped void corresponding to a component, a pre-formed element for locating in the shaped void and a powder for filling a remaining volume of the shaped void. The shaped void may be formed by an inner canister and an outer canister. The pre-formed element may contact the canister within the shaped void. Alternatively, the pre-formed element may be encapsulated by the powder on all sides such that it does not contact the canister.
The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore except where mutually exclusive any feature described herein may be applied to any aspect and/or combined with any other feature described herein.
Examples will now be described, with reference to the Figures, in which:
With reference to
The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.
The compressed air exhausted from the high-pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate, and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14, and fan 13, each by suitable interconnecting shaft.
Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.
The gas turbine engine comprises an engine casing 100 which houses the compressors 14, 15, the combustion equipment 16, and the turbines 17, 18, 19. The engine casing 100 is generally cylindrical, and may be formed of multiple casing sections of different diameters sized according to the respective part of the engine contained therein.
Turning now to
As shown in
The casing 100 has an area of increased thickness to form the boss 104. In order to form the flat boss surface 112, the boss thickness Tb varies across the width of the boss due to the curvature of the casing 100. The boss thickness Tb is greater than the general casing thickness Tc across the entire boss 104, but the boss thickness Tb is at a maximum at the outer edges of the boss surface 112 due to the curvature of the casing 100.
Shown in
An aperture (not shown) is provided in either the inner or outer canister to allow powder 212 to be fed into the void 210. The powder 212 is a fine particulate of the material from which the casing 100 will be formed. In the present case, the powder 212 is a metallic powder, but it will be understood that the powder could be formed from other materials, such as ceramics or polymers. Although the powder 212 is formed of solid particles, the term ‘solid’ used herein should be understood to mean a unitary solid which is not a particulate.
Referring to
Once the void 210 is filled with powder 212, the aperture is sealed, and so the void 210 is made airtight. The canisters 202, 206 are then places in a pressure vessel and heated at high temperature and pressure for a predetermined period of time. The powder 212 in the void is compressed and heated during this hot isostatic pressing (HIP) process such that it amalgamates into a solid component.
Once the heat and pressure cycle is complete, the powder 212 and the pre-formed element 214 is amalgamated or conglomerated into a contiguous solid casing 100 comprising the main body and the boss 104. The canisters 202, 206 are then removed using machining techniques, acid etching, or a combination thereof. As the HIP occurs, the powder 212 reduces in volume as the voids therebetween are compressed. The reduction may be either randomised about the component, or may be a constant percentage reduction in the volume compared to the original size of the void 210.
However, since the pre-formed element 214 is already a solid mass, it will not reduce in volume during the HIP process like the powder 212. Thus the element 214 serves to reduce local volumetric reduction due to the compression of the powder 212. This can reduce a dishing effects in thicker areas of the casing 100 which can occur when performing powder-only HIP. As the element 214 is of the same material as the powder 212, the powder and the element amalgamate or conglomerate into a single homogenous piece during the HIP process such that no boundary is present between them in the finished casing 100. Thus, by combining powder 212 with a pre-formed element 214 in the void 210, a casing 100 having the desired mechanical properties can be obtained with the HIP process without extensive further machining required due to non-uniform volume reduction or ‘dishing’. The element 214 itself may be formed by a HIP process. Alternatively, the element 214 may be formed by other means, such as casting, sintering, or machining from bar.
In
Various other elements 214 are shown in
As shown in
Any of the elements 214 shown herein may be held in place using pins 215 as shown in
In a further arrangement shown in
Any of the elements described herein may further comprise a bore cavity for forming or partially forming a bore through the casing 100. For example, the outer canister 206 of
It should be understood that multiple elements 214 may be utilised to form a casing 100, particularly where multiple bosses 104 or ducts 114 are required.
It should also be understood that the present methods are not only applicable to aerospace applications such as gas turbine engine casings. The present methods may be used in other fields for reducing dishing in any component produced using HIP.
It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1700614.9 | Jan 2017 | GB | national |
