Datum positioning in dies

Abstract

An assembly for hot forming a component includes first and second location features reversibly attached to a sheet metal element that forms the component. The assembly is loaded into a high temperature forming rig by loosely locating the location features into corresponding datum features in a forming tool. As the assembly heats up, the location features locate accurately with the datum features. Thus, the assembly can be accurately located onto the tool accurately and with minimal opening of the hot forming rig, thereby improving efficiency and safety.

Claims

1. A method of hot forming a component comprising: reversibly attaching a location feature to a base element from which the component is to be formed, the location feature protruding from the base element, the location feature and the base element forming an assembly; opening a pre-heated high-temperature forming rig containing a pre-heated forming tool; loading the assembly into the opened forming rig by locating the location feature into a corresponding datum feature in the forming tool; closing the forming rig; allowing the component to form at high temperature in the forming rig; re-opening the forming rig and removing the formed component from the forming rig; and removing the location feature from the formed component.

2. A method of hot forming a component according to claim 1, wherein: the component being formed is a metallic component; and the base element is a sheet metal element.

3. A method according to claim 1, wherein the step of removing the location feature from the formed component is performed by reversing the process used to reversibly attach the location feature to the base element.

4. A method according to claim 1, wherein: the forming rig remains closed from after the assembly has been loaded until it is re-opened for removal of the formed component.

5. A method according to claim 1, wherein: the step of loading the assembly into the forming rig is automated.

6. A method according to claim 1, wherein: the assembly is loaded into the forming rig at a lower temperature than that inside the rig; and the location feature expands so as to engage with and accurately locate in the corresponding datum feature as the temperature of the assembly rises inside the rig.

7. A method of forming at least two components comprising: hot forming a first component according to the method of claim 1; and subsequently hot forming a second component according to the method of claim 1, wherein: the location feature used in the hot forming of the second component is the same location feature that was removed from the formed first component.

8. A method of manufacturing a component according to claim 1, further comprising performing at least one finishing operation on the or each formed component wherein, optionally, at least one of the at least one finishing operations is trimming the formed component.

9. A method according to claim 1, wherein: the or each component is formed by superplastic forming.

10. A method according to claim 1, wherein: the or each component is at least a part of a fairing of a gas turbine engine.

11. A method of hot forming a component according to claim 1, wherein: the location feature is a first location features that is located into a first datum feature; the assembly further comprises a second location feature; and the step of loading the assembly into the opened forming rig further comprises locating the second location feature into a corresponding second datum feature in the forming tool.

12. A gas turbine engine comprising a component manufactured at least in part using the method of claim 1.

13. A method according to claim 1, wherein the pre-heated high-temperature forming rig and the pre-heated forming tool are both warmer than the assembly when performing the loading of the assembly into the opened forming rig.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples will now be described by way of example only, with reference to the Figures, in which:

(2) FIG. 1 is a sectional side view of a gas turbine engine; and

(3) FIG. 2 is a flow diagram showing an example of a method in accordance with the present disclosure;

(4) FIGS. 3A-3F are schematics that illustrate the steps used to form an assembly in accordance with an example of the present disclosure;

(5) FIG. 4 is a schematic showing an example of a location feature; and

(6) FIG. 5 is a schematic showing an example of a location feature.

DETAILED DESCRIPTION OF THE DISCLOSURE

(7) With reference to FIG. 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.

(8) 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.

(9) 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.

(10) 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.

(11) Various components of a gas turbine 10 engine such as that shown by way of example in FIG. 1 may be manufactured using a hot forming process. In such a process, it is generally necessary to load an assembly (comprising the material from which the component is to be formed) into a high temperature rig, such as a furnace. Purely by way of example, a component formed in this manner may be a fairing, such as a core fairing 50 (which may be a non-acoustic core fairing 50).

(12) As mentioned elsewhere herein, conventional arrangements and methods for loading such assemblies into high temperature forming rigs have various associated problems. The method illustrated purely by way of example by the flow chart in FIG. 2 and the apparatus illustrated in FIGS. 3A to 5 may alleviate and/or substantially remove such problems, and are described in further detail below. FIGS. 3A-3F illustrate the steps used to form an assembly 100 (which may be referred to as a sheet metal assembly 100) in an assembled state. FIGS. 4 and 5 show location features 200, 300 in greater detail, in particular during reversible attachment to a sheet metal element 400 in order to form the assembly 100. The sheet metal element 400 is an example of a base element 400 as referred to elsewhere herein. Thus, the terms base element and sheet metal element may be interchangeable.

(13) Referring to FIG. 2, in step S10 the location features 200, 300 shown in FIGS. 3A, 4 and 5 are reversibly attached to the sheet metal element 400. FIG. 3A shows the location features 300, 400 attached to the sheet metal element 400, the location features 300, 400 forming an assembly. FIG. 4 shows the location feature 200 in greater detail, in an exploded view. The location feature 200 has a first part 210 on a first side 410 of the sheet metal element 400, and a second part 220 on a second side 420 of the sheet metal element 400.

(14) A location feature may pass through the sheet metal element 400 when assembled, as shown by way of example for the location feature 200 shown in FIG. 4. In order to achieve this, the first part 210 passes through the sheet metal element 400, from the first side 410 to the second side 420. The first part 210 and the second part 220 on the second side 420. The first part 210 is then reversibly attached (or connected) to the second part 220 of the location feature 200 on the second side 420 of the sheet metal element 400. In the example shown in FIG. 4, the connection of the first part 210 to the second part 220 is achieved using a pin 230. The pin passes through a connecting hole 214 in the first part 210 and a corresponding connecting hole 224 in the second part 220, thereby reversibly attaching the first part 210 to the second part 220, and thus reversibly attaching the location feature 200 to the sheet metal element 400.

(15) Once assembled (not shown in FIG. 4) the location feature 200 can be removed from the sheet metal element 400 (for example after the forming process is completed) simply by performing the reverse operation to that used to connected the location feature 200 to the sheet metal element 400. In the FIG. 4 example, the location feature 200 can be removed from the sheet metal element 400 by removing the pin 230 and then separating the first part 210 of the location feature 200 from the second part 220.

(16) It will be appreciated that the pin 230 is merely one example of many connecting elements 230 that may be used to connected the first and second parts 210, 220 together (such as, for example, screw threads, pins and/or clips).

(17) The first part 210 of the location feature 200 referred to above may be used to locate the assembly 100 into a tool 500 (as described below in relation to step S30), and so may be referred to as a locating part 210 of the location feature 200. In this regard, the first (or locating) part 210 has a location element 212. As described in greater detail elsewhere herein, the location element 212 is shaped to engage with a corresponding datum feature 510 in a forming tool 500, shown in FIG. 3C.

(18) The second part 220 of the location feature 200 referred to above may be used to lift the assembly 100 onto the forming tool 500 shown in FIG. 3C, and so may be referred to as a lifting part 220. In order to achieve this, the second part 200 of the FIG. 4 example is provided with a lifting element 222, which may be referred to as a lifting eye 222. The lifting eye 222 may take any suitable form, for example any form that allows a suitable lifting tool to be used. In the FIG. 4 example, the lifting eye 220 is simply a loop into which a lifting bar may inserted in order to then lift the assembly 100.

(19) FIG. 5 shows an alternative example of a location feature, having reference numeral 300. The location feature 300 has a first portion 310 that, when reversibly attached to the sheet metal element 400, extends away from the first major surface 410. The location feature 300 has a second portion 320 that, when reversibly attached to the sheet metal element 400, extends away from the second major surface 420. In the FIG. 5 example, the first portion 310 and the second portion 320 are integrally formed.

(20) The exemplary location feature 300 of FIG. 5 is reversibly attached to an edge, or edge portion, of the sheet metal element 400. The location feature 300 of FIG. 5 may be said not to be surrounded by the sheet metal element 400 when it is reversibly attached thereto.

(21) In order to reversibly attach the location feature 300 to the sheet metal element 400, a clip 330 is used. The clip 330 is used to reversibly attach an engagement portion 325 of the location feature 300 and an engagement portion 425 of the sheet metal element 400. The clip 330 may be in the form of a tapered wedge, as in the FIG. 5 example. In this example, the wedge/clip 330 can be driven into the slot formed by the engagement portions 325, 425 (to the left in FIG. 5) in order to wedge (or clamp) the location feature 300 to the sheet metal element 400.

(22) The first portion 310 of the location feature 300 comprises a location element 312. The second portion 320 of the location feature 300 comprises a lifting element 322, which may be referred to as a lifting eye 322. The location element 312 and lifting element 322 of the FIG. 5 example may be substantially the same as the location element 212 and the lifting element 222 of the FIG. 4 example, and so will not be described in greater detail.

(23) It will be appreciated that any suitable location feature could be reversibly attached, and those shown in detail in FIGS. 4 and 5 are merely exemplary. Furthermore, although the assembly 100 shown in FIG. 3 is provided with one location feature 200 and one location feature 300, any suitable number and type of location features may be provided, for example depending on the type (for example size and/or shape and/or material) of assembly and/or the type of component being formed (for example size and/or shape and/or material) and/or the type of forming process. Purely by way of example, an axisymmetric article may one require one location feature (although a site location feature may also be used for arrangements other than axisymmetric).

(24) The sheet metal element 400 may be any type of sheet metal element, for example depending on the type (for example size and/or shape and/or material) of assembly and/or the type of component being formed (for example size and/or shape and/or material) and/or the type of forming process. Purely by way of example, the sheet metal element 400 may be so-called skin pack, which may have at least two metallic parts (such as sheets) seam welded and/or stich welded together. Such a skin pack 400 (or any other suitable sheet metallic element 400) may be formed into the desired shape using a super plastic forming (SPF) process.

(25) Returning to FIG. 2, in step S20 the high temperature forming rig 600 (which may be, for example, an SPF rig) containing a pre-heated forming tool 50 is opened as illustrated by FIG. 3B (represented schematically as the space that is not entirely surrounded by the square box that surrounds the forming tool 500 in FIG. 3B). The high temperature forming rig 600 is at an elevated temperature, such as a temperature described and/or claimed elsewhere herein. Because of the elevated temperature of the rig, any period of time that the rig is open represents a health and safety risk and/or a reduction in energy efficiency (for example due the heat energy that escapes when the rig is open) and/or a reduction in process (for example time) efficiency (for example due to the time taken for the rig to be heated back to the desired temperature). The assemblies described and/or claimed herein reduced and/or minimize the time that the forming rig is open and/or reduce the risk to human operators to the rig.

(26) In step S30, the assembly 100 is loaded into the opened high temperature forming rig 600 as illustrated in FIG. 3C. The assembly 100 is lifted via the lifting eyes 222, 322 of the location features 200, 300. For example, lifting arms/rods may be inserted through the lifting eyes 222, 322. Such arms may be sufficiently long to minimize the risk to any human operators. Additionally or alternatively, as described in greater detail below, the arrangement of the assembly 100, for example the location features 200, 300 may allow the loading process to be automated.

(27) The assembly 100 is loaded onto a forming tool 500, as shown by way of example in FIG. 3C. The location features 200, 300 are located with corresponding datum features 510, 520. In the illustrated example, the location features 200, 300, specifically the location elements 212, 312, are located in the corresponding datum features 510, 520 of the forming tool 500.

(28) The temperature of the assembly 100 is significantly lower than the temperature of the forming tool 500, which has been (and is) in the high temperature rig 600.

(29) The location features 200, 300 fit relatively loosely in the corresponding datum features 510, 520 when the much cooler assembly 100 is initially located on the forming tool 500.

(30) The initial position of the assembly 100 relative to the forming tool 500 may be only approximately correct when initially loaded due to the relatively loose fit of the location features 200, 300 in the datum features 510, 520. This may help to make loading the assembly 100 straightforward, as it does not require precise positioning. Accordingly the time required to perform step S30 may be substantially minimized, and step S40closing the high temperature forming rigcan be performed as soon as possible after step S20.

(31) After the high temperature forming rig is closed in step S40 (represented schematically as the space defined by the square box that surrounds the assembly 100 in FIG. 3D), the temperature of the loaded assembly 100 rises. The rising temperature cause thermal expansion. As the assembly 100, including the location features 200, 300, expands, the location features 200, 300 move relative to the datum features 510, 520, for example by expanding in and/or translating relative to the datum features 510, 520. This thermal movement accurately (which may include repeatably) locates the assembly 100 relative to the tool 500, in step S50. Accordingly, the assembly 100 may be positioned only approximately during the loading step S30, but the final, forming, position of the assembly 100 relative to the tool 500 may still be accurate. The assembly 100 may be said to be self-locating on the tool 500, in that its initial location on the tool 500 may not impact the final, accurate, location. Accordingly, it may be possible to accurately locate the assembly 100 on the tool 500 without opening the high temperature rig 600 more than once.

(32) The accurately located assembly 100 then undergoes high temperature forming in step S60. In the high temperature forming step S60, the sheet metal element 400 of the assembly 100 may be formed into a desired component (or at least into a component that can be further processed into a desired/finished component). The high temperature forming step S60 may be, for example, super plastic forming.

(33) After the forming step S60 is complete, the rig 600 may be re-opened in step S70, and the formed assembly removed as illustrated in FIG. 3E. Removal of the formed assembly may be substantially the reverse of the loading step S30. Thus, for example, the removal may by performed using the lifting eyes 222, 322 and/or the removal may be automated. The opening of the rig 600 in the step S70 may be the first time that the rig 600 has been opened since it was closed in step S40 after the loading step S30.

(34) After the formed assembly has been removed in step S70, the location features 200, 300, may be removed, or detached, from the rest of the assembly in step S80, for example after the assembly has cooled as illustrated in FIG. 3F. The removal of the reversibly attached location features 200, 300 may be completed by performing the reverse process to that used to reversibly attach the location features in step S10. For example, the location feature 200 may be removed by removing the pin 230, then separating the first part 210 from the second part 220. The location feature 300 may be removed by removing the clip 330, then separating the location feature 300 from the formed component. In general the process of removing any location feature may be substantially the reverse of the process of reversibly attaching the location feature. Removed location features 200, 300 may, if required, be re-used in subsequent forming processes. Thus, for example, the location features 200, 300 removed in step S80 may be the same location features 200, 300 that are subsequently used in step S10 of a subsequent forming process.

(35) 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.