Conical Shoulder Mount Pin Assembly for Misalignment Relief
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Solution Overview
Problem
Existing pin mounting strategies in gas turbine engines face issues with thermal stress and misalignment due to manufacturing tolerances, leading to potential installation binding and stress, particularly in designs with self-locking threads, which can result in undesirable load transfer through bolt threads in shear.
Innovation Solution
A load distributing self-locking mount pin assembly featuring a conical shoulder region on the pin that contacts a chamfered aperture, combined with a self-locking nut plate, allowing for anti-rotation and weight reduction by distributing load through normal compressive loading rather than friction, and utilizing a specialized drill bit for concurrent aperture and chamfer formation to minimize residual assembly stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-locking thread design is used to prevent rotation and ensure secure mounting, then reliability is improved, but installation binding and stress occur due to misalignment between the insert and clevis holes from manufacturing tolerances
Solution Approach 1:
The conical chamfer is pre-formed on the pin at a specific angle (e.g., 60 degrees) that matches the conical shoulder geometry. This preliminary geometric preparation ensures that during assembly, the conical surfaces guide the pin into proper alignment with the clevis holes before the self-locking threads engage, preventing installation binding caused by tolerance accumulation.
Solution Approach 2:
The invention changes the geometric parameters of the pin by adding a conical shoulder with a specific cone angle that corresponds to the chamfer angle. This parameter change creates a self-aligning mechanism where the conical surfaces contact first during installation, establishing the correct angular orientation and position before the threaded portion engages with the clevis, thereby eliminating misalignment stress.
2Ease of manufacture
If clearances are increased on the hole or bushing to mitigate misalignment issues, then ease of manufacture is improved, but a larger percentage of load is transferred through the bolt threads in shear which is structurally undesirable
Solution Approach 1:
The conical chamfer and shoulder geometry are prepared in advance to create a self-aligning interface. This preliminary geometric configuration ensures that during assembly, the conical surfaces establish proper alignment and contact, guiding the pin into the correct position before the threaded portion engages. This eliminates the need for increased clearances and ensures load is properly distributed through the conical contact surfaces rather than being concentrated in the threads.
3Weight of moving object
If a lighter weight pin design is used to reduce overall component weight, then weight of moving object is improved, but thermal stress and misalignment issues arise from simplified mounting geometry
Solution Approach 1:
The invention employs conical (curved) surfaces instead of flat or cylindrical interfaces. The conical chamfer on the pin and the corresponding conical shoulder create a tapered geometric profile that provides self-aligning capabilities. This curved geometry allows the pin to naturally accommodate thermal expansion and misalignment by distributing contact stresses over the conical surface area, reducing peak thermal stresses while maintaining a lightweight design.
Data Source
AI summary
A mounting pin assembly includes a first mounting component. The assembly also includes a second mounting component having a first leg located on a first side of the first mounting component and a second leg located on a second side of the first mounting component. The assembly further includes a mount pin extending through an aperture of the first leg, an aperture of the first mounting component, and an aperture of the second leg, the mount pin having a conical shoulder region in contact with a chamfer of the second leg. The assembly yet further includes a self-locking nut plate threaded to the mount pin.