Wing Sub-Assembly With Floating Nut for Hole Misalignment
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Solution Overview
Problem
Existing aircraft wing manufacturing processes face challenges with hole misalignment due to tolerance stacking and thermal expansion, leading to time-consuming re-adjustments and potential parts wastage. Additionally, the need for access to both sides of each joint for bolt tightening imposes design constraints and increases assembly time.
Innovation Solution
A wing sub-assembly featuring a structural component with a bolt aperture and a nut retention structure that aligns an internally-threaded nut with the aperture, allowing limited lateral movement. This design eliminates the need for operators to support the nut during bolt insertion and allows for joint assembly using pre-drilled holes without adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional manufacturing processes with pre-drilled holes are used, then assembly is simpler, but hole misalignment occurs due to tolerance stacking and thermal expansion
Solution Approach 1:
The nut is pre-installed in the structural component before assembly with the skin, allowing the bolt hole to be drilled through both components simultaneously in one operation. This preliminary positioning eliminates the need for separate alignment operations and accommodates tolerance variations.
Solution Approach 2:
The nut acts as an intermediary element that bridges the structural component and the skin. By pre-installing the nut in the structural component, it serves as a reference feature that facilitates accurate hole drilling through both parts while accommodating dimensional variations.
2Reliability
If operators support the nut during bolt tightening, then proper tightening is achieved, but assembly time increases and design constraints are imposed
Solution Approach 1:
The structural component with the pre-installed nut performs the alignment function that would otherwise require operator intervention. The nut's position in the structural component automatically guides the bolt, eliminating the need for operators to manually support or position the nut during assembly.
3Manufacturing precision
If match-drilling with pilot holes is used, then hole alignment improves, but drilling complexity increases and swarf removal becomes difficult
Solution Approach 1:
The nut is pre-installed in the structural component to serve as a positioning reference. This allows the drilling operation to be performed in a single step through both the structural component and skin, eliminating the need for multiple drilling stages and reducing swarf management complexity.
Data Source
AI summary
A wing is manufactured from a sub-assembly made up of a structural component such as a wing rib, and a nut. The structural component has a first seating surface for supporting a lower skin of the wing and a second seating surface for supporting an upper skin of the wing. An aperture extends along an aperture axis, through one of the seating surfaces. A nut retention structure of the structural component holds the nut aligned with the aperture, but allows the nut to move laterally relative to the aperture axis so as to accommodate slight misalignment between the aperture and a hole in one of the skins.