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Improved Aircraft Landing Gear Assembly and Method of Manufacture
GB2493744A
United Kingdom
- Inventor
Andraz Vatovec Germain Forgeoux - Current Assignee
- Safran Landing Systems UK Ltd
Worldwide applications
Application GB1114157.9A events
2011-08-17
2011-08-17
2011-10-05
2012-08-06
2013-02-20
2014-08-27
Application granted
2014-08-27
Status
Active
2031-08-17
Anticipated expiration
Description
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Improved Aircraft Landing Gear Assembly and Method of Manufacture
Background to the Invention.
Aircraft landing gear assemblies are typically subjected to high loading conditions during normal use, i.e. during aircraft landings and ground operations. The larger and heavier the aircraft the greater these loadings are. Consequently high strength/performance materials, such as aluminium and/or titanium alloys, are used for some of the landing gear components. Large components, such as bogie beams or sliders, are subsequently typically produced from large mono-block forgings, where the entire component is manufactured from the same material, or alternatively manufactured as several sub-components joined by mechanical joints.
Both of the methods of manufacture mentioned above have disadvantages. For large components made from mono-block forgings the most stressed portion of the component when the gear is in use drives the selection of the high performance material for that forging. The same material must therefore be used for the entirety of the component, regardless of the stress requirements/expectations of the rest of the component. More of the high performance, and therefore expensive, material is therefore used than is strictly necessary. To subsequently minimise the cost and weight of the mono-block forgings the component design typically includes complex design features that may present difficulties in subsequent machining and manufacturing processes. The joining of multiple sub-components using mechanical joints tends to increase the overall weight of the final component because of the additional material required to form the mechanical joints whilst maintaining the desired overall strength of the component. The mechanical joints also tend to be relatively complex and elaborate to manufacture.
It has also been known to manufacture landing gear assemblies by manufacturing several sub-components from the same material and subsequently welding the sub-components together, the same material being used for all sub-components to facilitate the welding process. However, as with the mono-block forgings, the use of the same material, that material being selected as a function of the highest expected stresses of any of the sub-components, does not allow the selection of the optimum material for each sub-component. Subsequently, the majority of the sub-components are over engineered and therefore more expensive than strictly required.
There therefore remains a requirement to manufacture a landing gear assembly in which the optimum material for each sub-component may be selected, whilst reducing or overcoming the disadvantages mentioned above.
Summary of the Invention.
According to a first aspect of the present invention there is provided a method of manufacturing an aircraft landing gear component having a plurality of sub-components, the method comprising forming first and second sub-components from dissimilar materials and welding said sub-components together to form the landing gear component.
The sub-components are preferably welded together using any one of rotary friction welding and electron beam welding, although other welding techniques known to the skilled person may be used.
At least one of the sub-components may be machined prior to welding.
In preferred embodiments, the material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the material.
According to a second aspect of the present invention there is further provided an aircraft landing gear assembly comprising a first sub-component of a first material and a second sub-component of a second, dissimilar, material, the first and second sub-components being welded together.
Preferably the material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the material.
The sub-components may be welded together using any one of rotary friction welding and electron beam welding, or any other known welding technique.
The landing gear assembly may comprise a side stay in which the first component comprises at least one lug arranged to be pivotably connected to a further section of an aircraft and the second component comprises an elongate body element.
Brief Description of the Figures
Embodiments of the present invention are described below by way of non-limiting examples only with reference to the accompanying figures, of which: Figure 1 illustrates a method of manufacture of an aircraft landing gear assembly according to an embodiment of the present invention.
Detailed Description of Embodiments of the nvention.
Figure 1 schematically illustrates individual steps in the manufacture of an aircraft landing gear assembly in accordance with an embodiment of the present invention.
In the example illustrated, the landing gear assembly 2 has two sub-components 4, 6. However, it will be appreciated that the method of the present invention is equally applicable to assemblies having a greater number of sub-components and the example illustrated is of minimal complexity to aid the understanding of the reader.
First, the individual sub-components 4, 6 are individually manufactured, for example as simple forgings, castings or taken from stock items (such as stock tubes). The material for each subcomponent is selected according to the desired physical properties for that individual sub-component. Examples of the physical properties used in selecting the material for each sub-component include cost, strength, weight, fatigue resistance, stiffness andcorrosion resistance. The individual sub-components replace one large and complex element in the prior art.
Next, simple machining operations are optionally performed on one or more of the sub-components as required such that each sub-component is machined to final or near final shape 4a, 6a. The machining operations for each sub-component is less complex to achieve than for prior art single, larger, components due to their reduced size and complexity of basic shape. Additionally, the reduced complexity of the machining required means that smaller, less complex machining units can be used that are typically cheaper to purchase and maintain (and possibly cheaper to operate). In some embodiments of the present invention, depending on the complexity of the desired final shape of a sub-component the machining operation can be omitted. Next, the individual sub-components 4a, 6a are welded together to form the final landing gear assembly 2a. In preferred embodiments the welding techniques used include friction welding, and in particular rotary friction welding, and electron beam welding. Both of these techniques, which are techniques known in the general art of welding and are therefore not described in detail here, are particularly suitable for the welding of dissimilar materials. However, other techniques for welding dissimilar materials may be used within the scope of the present invention.
By the use of multiple sub-components welded together single landing gear assemblies can be produced from multiple materials, thus allowing each section (sub-component) to be manufactured from the most suitable material for that particular section in terms of material characteristics and/or cost. The simplification of the optionally required machining steps of the individual sub-components, due to their reduced size in comparison with the final assembly, also reduces the manufacturing cost. For example, a side stay may be produced in accordance with embodiments of the present invention in which the stay includes separate end sections in which the (pivotable) attachment lugs are formed from a high strength/quality material (as the lugs may experience high stresses in use), with the lugs being welded to either end of the main elongate stay body that is manufactured from a second, dissimilar, material of lower strength, The main body of the stay tends not to experience the levels of stress that the lugs do and need not, therefore, be manufactured from the same high strength (and high cost) material as the lugs.
The use of welds, facilitated by the use of techniques suitable for welding dissimilar materials, eliminates the requirement for mechanical joints that would otherwise be required to join multiple sub-components and which would in themselves undesirably increase the mass of material needed for each sub-component (to form the mechanical joint) and therefore their weight and cost.
Claims (8)
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Claims (8)
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- <claim-text>Claims.1. A method of manufacturing an aircraft landing gear component having a plurality of sub-components, the method comprising: forming first and second sub-components from dissimilar materials; and welding said sub-components together to form the landing gear component.</claim-text> <claim-text>2. A method of manufacture according to claim 1, wherein said sub-components are welded together using any one of rotary friction welding and electron beam welding.</claim-text> <claim-text>3. A method of manufacture according to claim 1 or 2, wherein at least one of the sub-components is machined prior to welding.</claim-text> <claim-text>4. A method of manufacture according to any preceding claim, wherein the material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the material.</claim-text> <claim-text>5. An aircraft landing gear assembly comprising a first sub-component of a first material and a second sub-component of a second, dissimilar, material, the first and second sub-components being welded together.</claim-text> <claim-text>6. An aircraft landing gear assembly according to claim 5, wherein the material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the material.</claim-text> <claim-text>7. An aircraft landing gear assembly according to claim 5 or 6, wherein said sub-components are welded together using any one of rotary friction welding and electron beam welding.</claim-text> <claim-text>8. An aircraft landing gear assembly according to any one of claims 5 to 7 comprising a side stay in which said first component comprises at least one lug arranged to be pivotably connected to a further section of an aircraft and said second component comprises an elongate body element.SAMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS1. A method of manufacturing a complex aircraft landing gear component having a plurality of sub-components, the method comprising: forming first and second sub-components from dissimilar materials, wherein each sub-component is formed to final or near final shape; and welding said sub-components together to form the complex aircraft landing gear component.
- 2. A method of manufacture according to claim 1, wherein said sub-components are welded together using any one of rotary friction welding and electron beam welding.
- 3. A method of manufacture according to claim 1 or 2, wherein at least one of the sub-components is machined prior to welding.LIt)
- 4. A method of manufacture according to any preceding claim, wherein the C material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the r 20 material.
- 5. An aircraft landing gear assembly comprising a first sub-component of a first material and a second sub-component of a second, dissimilar, material, the first and second sub-components being welded together.
- 6. An aircraft landing gear assembly according to claim 5, wherein the material for each sub-component is selected in dependence on one or more of the desired mechanical properties of said sub-component and cost of the material.
- 7. An aircraft landing gear assembly according to claim 5 or 6, wherein said sub-components are welded together using any one of rotary friction welding and electron beam welding.
- 8. An aircraft landing gear assembly according to any one of claims 5 to 7 comprising a side stay in which said first component comprises at least one lug arranged to be pivotably connected to a further section of an aircraft and said second component comprises an elongate body element. (4 rLID</claim-text>