Alignment tool

Abstract

There is disclosed an alignment tool for positioning an impact liner panel on a fan casing. The alignment tool comprises an attachment portion for attaching to the fan casing, a support surface for receiving a shim, and a magnet to magnetically retain a shim on the support surface. There is also disclose a tool kit for manufacturing a fan casing having an alignment tool and a shim. There is also disclosed a method of positioning an impact liner panel on a fan casing. It comprises attaching an alignment tool to the fan casing, magnetically retaining a shim on a support surface of the alignment tool; and positioning the impact liner panel against an abutment surface of the shim.

Claims

1. A method of positioning an impact liner panel on a fan casing, the method comprising: attaching an alignment tool to the fan casing; magnetically retaining a shim on a support surface of the alignment tool; and positioning the impact liner panel against an abutment surface of the shim.

2. The method according to claim 1, comprising applying a layer of adhesive to the fan casing before positioning the impact liner panel, and curing the adhesive in a curing operation to secure the impact liner panel to the fan casing.

3. The method according to claim 2, comprising removing the alignment tool from the fan casing after curing the adhesive to secure the impact liner panel to the fan casing.

4. The method according to claim 1, comprising retaining a magnetic shim on the support surface, wherein the alignment tool comprises an embedded magnet.

5. The method according to claim 1, further comprising checking an axial position of the impact liner panel and, if the impact liner panel is not correctly axially located with respect to the fan casing, removing the shim, or replacing the shim with a shim of different thickness, and/or adding one or more additional shims to axially move the abutment surface within the fan casing as required.

6. A tool kit for manufacturing a fan casing, the tool kit comprising: an alignment tool for positioning impact liner panels on a fan casing, the alignment tool comprising: an attachment portion for attaching to the fan casing; a support surface for receiving a shim; and a magnet to magnetically retain a shim on the support surface; and a shim configured to be magnetically retained on the support surface of the alignment tool.

7. The tool kit according to claim 6, comprising a plurality of alignment tools and a plurality of shims.

8. The tool kit according to claim 6, wherein the alignment tool is configured to retain more than one shim.

9. The tool kit according to claim 6, wherein the magnet is embedded within the alignment tool.

10. The tool kit according to claim 6, comprising a flange defining the support surface.

11. The tool kit according to claim 6, wherein the alignment tool comprises fibre reinforced polymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments 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;

(3) FIG. 2 shows a cross sectional view of an alignment tool;

(4) FIG. 3 shows a cross-sectional view of a fan casing with a tooling assembly in use to position an impact liner on a fan casing; and

(5) FIG. 4 is a flow chart showing steps of a method for positioning impact liner panels on a fan casing.

DETAILED DESCRIPTION

(6) FIG. 1 illustrates a gas turbine engine 10 having a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic gearbox 30.

(7) In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into 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 is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 generally provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

(8) Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in FIG. 1 has a split flow nozzle 20, 22 meaning that the flow through the bypass duct 22 has its own nozzle that is separate to and radially outside the core engine nozzle 20. However, this is not limiting, and any aspect of the present disclosure may also apply to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed, or combined, before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. Whilst the described example relates to a turbofan engine, the disclosure may apply, for example, to any type of gas turbine engine, such as an open rotor (in which the fan stage is not surrounded by a nacelle) or turboprop engine, for example. In some arrangements, the gas turbine engine 10 may not comprise a gearbox 30.

(9) The geometry of the gas turbine engine 10, and components thereof, is defined by a conventional axis system, comprising an axial direction (which is aligned with the rotational axis 9), a radial direction (in the bottom-to-top direction in FIG. 1), and a circumferential direction (perpendicular to the page in the FIG. 1 view). The axial, radial and circumferential directions are mutually perpendicular.

(10) FIG. 2 shows a cross sectional view of an alignment tool 100 for positioning impact liner panels on an inner surface of a fan casing. The alignment tool 100 comprises an attachment portion 102 and a flange 104 extending from the attachment portion 102. In this example, the alignment tool 100 is made from carbon fibre reinforced polymer (CFRP). However, in other examples the alignment tool may be made from any suitable material such as a metal, glass fibre reinforced polymer (GFRP) or any fibre reinforced composite material.

(11) The attachment portion 102 is configured to be attached to a fan casing. The attachment portion 102 has an arcuate profile corresponding to the profile of the fan casing where it is to be attached, so that a radially outer surface of the attachment portion 102 is configured to correspond to a radially inner surface of the fan casing, such that the attachment portion 102 can lie flush against the fan casing in use.

(12) The attachment portion 102 is generally elongate in a radial cross section along an axis corresponding to the central axis of the casing when installed.

(13) In this example, the attachment portion 102 comprises two holes 106 for receiving bolts for attachment to the fan casing (best shown in FIG. 3). In other examples the holes may be configured to receive a screw, the holes may be threaded and/or there may be more than two holes. In yet other examples the attachment portion may comprise an adhesive on the radially outer surface for adhering the alignment tool to the radially inner surface of the fan casing, or may be configured to be clamped to the fan casing.

(14) In this example, the flange extends perpendicularly with respect to the elongate direction of the attachment portion, such that it is normal to the axial direction of the fan casing when installed.

(15) The flange 104 defines a support surface 108 on an outer surface of the alignment tool 100 facing away from the rest of the alignment tool 100, for receiving a shim and/or to serve as an abutment surface for receiving an impact liner.

(16) A magnet 110 is embedded within the flange 104. In this example, the magnet 110 extends from an inner surface of the flange 104 proximate the attachment portion 102 and terminates under the support surface 108 of the flange 104. The magnet 110 may be positioned flush with the support surface 108 provided that it does not obstruct reception of a shim by protruding from the support surface 108. A shim may therefore be magnetically retained on the support surface 108 of the alignment tool 100.

(17) The magnet 110 is embedded in the flange 104 by drilling a hole through the flange 104, such as a through hole or a blind hole, after curing of the alignment tool 100, then applying adhesive in the hole and placing the magnet 110 in the hole so that it adheres to the flange 104. In other examples, the adhesive may be dispensed with and the magnet 110 may be embedded in the hole by interference coupling. In other examples, the magnet may be embedded in the flange during manufacture of the alignment tool i.e. during lay-up of the alignment tool.

(18) FIG. 3 shows a cross sectional view of a rear portion of a fan casing 200 with a tooling assembly 150 installed to accurately position a plurality of impact liners 350 around an inner surface of the fan casing 200.

(19) FIG. 3 shows a cylindrical fan casing 200 for simplicity, having a centreline 450 defining an axial direction of the fan casing 200. However, a fan casing may have a circular con-di (convergent and divergent) profile, or any other axially varying cross-sectional profile. It may be important to precisely axially locate the liner panels 350 in the fan casing 200 to ensure that the profiles of the fan casing and the liner panels match, particularly for axially varying profiles.

(20) In this example, the fan casing 200 is made of carbon fibre reinforced polymer (CFRP) and comprises a fan casing flange 202 at the rear end of the fan casing 200. FIG. 3 shows the fan casing flange 202 resting on a horizontal surface 400 such as the ground, such that the centreline 450 of the fan casing 200 is vertical. The fan casing 200 comprises a plurality of pairs of bolt holes 204 around its circumference, each at the same axial position along the fan casing 200, near the fan casing flange 202 for receiving a bolt 206. In some examples, the bolts may be secured with corresponding nuts. In other examples, the holes may be threaded holes for receiving the bolts, or the holes may receive a threaded insert for receiving the bolt.

(21) The tooling assembly 150 comprises a plurality of alignment tools 100, and a plurality of shims 130. In this example, there are eight alignment tools 100, and eight corresponding shims 130 (only four of each are shown in the cross section of FIG. 3). However, in other examples, there may be more or fewer alignment tools and shims. In yet other examples, there may be more shims than alignment tools. In this example, the number of alignment tools 100 corresponds to the number of liner panels 350 which are to be placed in the fan casing 200.

(22) The alignment tools 100 are evenly spaced around the fan casing 200, and each alignment tool 100 is substantially the same. Therefore, the tooling assembly 150 will be described below with respect to one alignment tool 100 and a corresponding shim 130.

(23) The alignment tool 100 is attached by the attachment portion 102 to the fan casing 200, with bolts 206. The alignment tool 100 is positioned within the fan casing 200 so that the flange 104 is located axially inwardly in the fan casing 200 relative the attachment portion 102, and extends radially inwards from the attachment portion 102, so as to support an end of a liner panel when the panel is disposed towards an axial centre of the casing.

(24) Although it has been described that the flange 104 of the alignment tool 100 is perpendicular to the attachment portion 102 of the alignment tool 100, the angle between the flange and the attachment portion may be any suitable angle such that the support surface 108 is oriented to co-operate with an end surface of a liner panel, for example by being substantially horizontal when the alignment tool 100 is attached to the fan casing 200, and the fan casing 200 rests on a horizontal surface as shown in FIG. 3.

(25) A shim 130 is magnetically retained against the support surface 108 of the alignment tool 100. The shim 130 is in the form of a steel plate with 1 mm thickness with a profile corresponding to the support surface 108 of the alignment tool 100. The shim 130 defines an abutment surface 138 for receiving an impact liner 350. The abutment surface 138 is the opposite surface to that which is received on the support surface 108 of the alignment tool 100. Either surface may be considered an abutment surface before use.

(26) Although it has been described that the shim 130 has a thickness of 1 mm, in other examples, the shim may have a thickness less than 1 mm or more than 1 mm such as comprised between 0.01 mm and 3 mm, for example 0.25 mm, 0.5 mm or 2 mm. In yet other examples, the tooling assembly 150 may comprise a plurality shims for each alignment tool, where the plurality of shims may have the same, or different thicknesses.

(27) The axial location of the abutment surface 138 along the fan casing can be easily changed by replacing the shim with a shim of different thickness. The alignment tool 100 may also be configured to magnetically retain more than one shim 130, so that the axial location of the abutment surface can be changed by adding or removing shims of the same or different thicknesses to be retained on the alignment tool 100.

(28) The liner panels 350 are located around the inner surface of the fan casing 200 so that an axial end of each liner panel rests on an abutment surface 138 of a shim, or if no shim is necessary, on the support surface 108 of the alignment tool 100. In this example, there are eight liner panels 350, each liner panel 350 resting on two alignment tools 100 on opposite sides of the axial end of the liner panel 350, such that one alignment tool 100 partially supports axial ends of two adjacent liner panels 350. A layer of adhesive 352, such as epoxy resin, is disposed between the liner panels 350 and the fan casing 200 to secure the liner panels 350 to the fan casing when the adhesive 352 is cured.

(29) FIG. 4 is a flow chart showing steps of a method 300 for positioning the impact liner panels 350 on the fan casing 200 and will be described by way of example with respect to the alignment tool 100 and shim 130 of FIGS. 2-3. The fan casing 200 rests on the horizontal surface 400 as shown in FIG. 3. In step 302, the plurality of alignment tools 100 are attached to the fan casing 200 as shown in FIG. 3. In step 304, a shim 130 of 1 mm thickness is retained on the support surface 108 of each alignment tool 100. In other examples, the shims may be magnetically retained on the respective alignment tools before the alignment tools are attached to the fan casing.

(30) In step 306, a layer of adhesive 352 is applied to the inner surface of the fan casing 200. In other examples, this step can be carried out before attaching the alignment tools to the fan casing, or before magnetically retaining the shims against the alignment tools.

(31) In step 308, the liner panels 350 are placed against the adhesive layer 352 and rest, under gravity, against the abutment surface 138 of the shim 130. In step 310, the axial positions of the liner panels 350 are checked to ensure that they are correctly located with respect to the fan casing 200. For example, the conformance of the profile of the liner panel to the profile of the fan casing may be checked at the axial location. If the liner panel are not correctly located, the method proceeds to step 312. If they are positioned correctly, the method proceeds to step 316.

(32) In step 312, the shim 130 is removed or replaced with a shim of different thickness, or another shim is added to be magnetically retained against the flange 104 of the alignment tool 100, to axially move the abutment surface 138 within the fan casing 200 as required. In step 314, the liner panels are re-positioned against the adhesive layer 352 and rest against abutment surface 138 of the shim 130, and the method returns to step 310 to check whether the liner panels are positioned correctly.

(33) In this example, the alignment tool 100 is made so that the support surface 108 of the flange 104 is 1 mm below the intended end position of the liner panel 350 so that the addition of a shim 130 of 1 mm brings the abutment surface 138 to the required axial location in the fan casing 200. In other words, the support surface 108 defines a lower limit for the intended end position of the liner panel 350. If the lower limit does not match the intended end position of the liner panel 350, one or more shims 130 of suitable thickness may be positioned on the flange 104 to adjust the position of the abutment surface 138 and therefore the axial position of the liner panel 350. Each alignment tool 100 can be adjusted individually and independently from each other.

(34) Once the liner panels 350 have been correctly positioned, the method proceeds to step 316. In step 316, a vacuum bag is applied over the impact liner panels 350 and tool assembly 150 on the fan casing 200, and the adhesive layer 352 is cured under elevated temperature and pressure (such as in an autoclave) to secure the liner panels 350 to the fan casing 200.

(35) Once the adhesive layer 352 has been cured, the tooling assembly 150 is removed from the fan casing 200. The shims and fan casing in this example are made from the same material (CFRP in this example), so that there is no differential thermal expansion during curing of the adhesive, so that the axial position of the liner panels 350 relative the fan casing 200 does not change during the curing of the adhesive.

(36) Since the alignment tool 100 has a magnet 110, the shim can be retained on the alignment tool magnetically, without requiring a layer of adhesive or tape, which would change the thickness or tolerance of the shim. Tape applied and removed repeatedly on a shim leaves a residue which requires regular cleaning to ensure that the thickness of the shim is not changed over time. Further, taping a shim to an alignment tool requires more consumables and is more time consuming than magnetically retaining the shim.

(37) Therefore, the magnetic alignment tool and shim allows quick and simple alteration of the axial location of the abutment surface for adjusting the axial position of the liner panels.

(38) Although it has been described that the shim is made of steel, in other examples, the shims may be made from any magnetic material.

(39) Although it has been described that the alignment tool is attached to the fan casing for providing a support surface, the alignment tool can take the form of any support which provides a horizontal support surface when the support is attached to the fan casing, and the flange of the fan casing is resting on the horizontal surface.

(40) Although it has been described that the alignment tool and shim are used for positioning impact liner panels on an inner surface of a fan casing, the alignment tool or tool kit can be used to align any components relative one another.

(41) 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.