Removable Locating Structures for Fan Casing Assembly
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Solution Overview
Problem
The assembly of fan casings for gas turbine engines is complicated by the need to position multiple components with tight tolerances, leading to inefficiencies in design flexibility, increased weight, time consumption, and cost, with existing methods such as dot peens or stamping systems being inadequate in controlling positional tolerances and maintaining strength.
Innovation Solution
An assembly fixture with a plurality of locating structures featuring apertures and positioning features that securely engage fasteners to indicate precise mounting locations on the fan casing, allowing for improved positional control and assembly efficiency, utilizing a combination of flanges and bolts to stabilize the fixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dot peens or shallow flat bottom holes are used for positioning, then positioning is achieved, but the fan case's strength under ultimate loading is reduced
Solution Approach 1:
The patent introduces removable locating structures as intermediary tools that provide positioning features during assembly. These structures temporarily mediate the positioning function without permanently deforming the fan case, allowing precise component placement while preserving the fan case's structural integrity for ultimate loading conditions.
2Ease of operation
If a system of stamping pistons and a rotating table is used for placement, then fasteners can be placed at selected locations, but the assembly process becomes complicated and requires large lead times
Solution Approach 1:
The patent divides the assembly fixture into multiple removable locating structures, each responsible for a specific positioning function. This segmentation allows the complex positioning task to be broken down into simpler, independent components that can be easily set up and removed, eliminating the need for complicated rotating tables and stamping pistons while maintaining precise placement capability.
3Productivity
If traditional assembly methods are used, then assembly can be performed, but positional tolerances are not well controlled resulting in 20% tolerance of base dimensions
Solution Approach 1:
The patent incorporates positioning features directly into the locating structures before assembly begins. These pre-configured locating structures establish precise reference positions and tolerances in advance, guiding component placement to achieve tight positional tolerances (25-50% improvement) without slowing down the assembly process.
Data Source
AI summary
An assembly fixture for a fan casing of a gas turbine engine wherein the fan casing includes a casing having a flange with a plurality of apertures extending therethrough, comprises a locating structure having a positioning feature that is engageable by a fastener extending through a particular aperture of the plurality of apertures to secure the locating structure to the fan casing. The locating structure further includes a locating feature indicating a particular location of the fan casing when the locating structure is mounted to the fan casing.