Patent Application
20070286760
The present invention will be more fully described by way of example with reference to the accompanying drawings in which:—
A hollow fan blade 10, as shown in
The hollow fan blade 10 is produced using a method described with reference to
In a third step the edge regions 40 and 42 of the two metal members 30 and 34 respectively are sealed together by seals 41 except for one open edge to form a core structure 44. It may also be possible to seal the two metal members 30 and 34 together at other regions where they contact. In a fourth step the core structure 44 is positioned in an open-ended mould 46 to define a cavity 48 between the external surface 50 of the core structure 44 and the internal surface 52 of the mould 46. The internal surface 52 of the mould 46 substantially defines the external shape of the hollow fan blade 10, as shown in
In the eighth step heat and pressure is applied externally of the mould 46 to consolidate the powder material 54, to diffusion bond the metal powder 54 together, to form the hollow fan blade 10 in the cavity 48 in the mould 46. The metal powder 54 also diffusion bonds to the metal members 30 and 34. In addition pressure is applied internally of the mould 46 within the chamber, or chambers, 38 to support the metal members 30 and 34 and to maintain the shape of the chamber, or chambers 38.
The application of heat and pressure externally of the mould 46 and the application of pressure internally of the mould 46 within the chamber, or chambers, 38 is by use of a gas, e.g. an inert gas for example argon, or a gas which is non-reactive with the metal members 30 and 34. Alternatively the application of pressure internally of the mould 46 within the chamber, or chambers, 38 may be by use of a liquid, e.g. a liquid metal, which is non-reactive with the metal members 30 and 34 and is a liquid under the temperatures and pressures experienced during the eighth, consolidation step.
In a final step the mould 46 is removed from the hollow fan blade 10, as shown in
It may be advantageous, in another subsequent step to inject a vibration damping material into a preselected one or more of the chambers 38 within the hollow fan blade 10. The vibration damping material may be a viscoelastic damping material.
The step of sealing the edge regions 40 and 41 of the metal members 30 and 34 preferably comprises welding, but brazing or other suitable processes may be used as long as the joint is gas tight.
The step of sealing the open edge of the metal members 30 and 34 to the mould 46 preferably comprises welding, but other suitable processes may be used. The step of heating and applying pressure preferably comprises hot isostatic pressing, but other suitable processes may be used.
The step of cold compressing preferably comprises cold pressing both metal members 30 and 34 to form at least one depression 32 and 34 respectively in each metal member 30 and 34. Alternatively it may be possible to form one or more depressions in only one of the metal members 30 or 34.
The metal members 30 and 34 may comprise titanium members or titanium alloy members. The metal powder may comprise titanium powder or titanium alloy powder.
The positioning of the core structure 44 in the mould 46 may comprise positioning the core structure 44 in an open-ended two-part mould.
The edge regions 40 and 42 of the core structure 44 may be clamped between the two parts of the mould 46.
The present invention has a number of advantages, the process is relatively cheap because cold pressing may be used to form the core structure from the metal members. The cold pressing of the metal members is very flexible, allowing metal to be placed exactly at the positions where it is required. Equally well, cavity size, shape and position may be finely controlled to achieve desired stress levels and life of the hollow article. This is particularly useful to allow the vibration damping material to be placed exactly where required. The powder metallurgy allows very efficient material usage to control costs. The process is repeatable, providing consistent quality. The mould halves may be reusable if made from a suitable material, for example by coating with a stop off material such that the powder material does not stick, or bond, to the two parts of the mould.
Although the present invention has been described with reference to the use of a pressure applied internally of the mould within the chamber, or chambers, to support the metal members to maintain the shape of the chamber, or chambers, it is equally possible to fill the cavities with a solid powder, liquid or other incompressible material to support the metal members and then subsequently remove, by melting, dissolving or pouring out, the solid powder, liquid or incompressible material through passages drilled to the chamber, or chambers.
Although the present invention has been described with reference to the metal members being clamped between the two parts of the mould, the metal members may simply rest in the correct position on the two parts of the mould if the metal members are the correct shape. The two parts of the mould may be pre-sealed together by welding, brazing etc before the metal members are placed in the mould or the two parts of the mould may be sealed together by welding, brazing etc after the two parts of the mould have been placed around the metal members.
Although the present invention has been described with reference to the manufacture of a hollow fan blade, it is equally applicable to the manufacture of other hollow articles, for example a hollow strut or other hollow aerofoil, such as a fan outlet guide vane or a compressor blade or a compressor vane.
Although the present invention has been described with reference to the manufacture of a hollow metal article using metal members and metal powder, or metal powders, it is equally possible to manufacture a hollow polymer articles using polymer members and polymer powder, or polymer powders.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0607228.4 | Apr 2006 | GB | national |
