Aircraft Structure Assembly Using 3D-Machined Self-Aligning Sections
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Solution Overview
Problem
Current aircraft part manufacturing and assembly processes rely heavily on 2D drawings, leading to gaps and inexact definitions, requiring shimming, multiple locating fixtures, and final-hole-size drill jigs, which are costly and prone to nonconformance.
Innovation Solution
The use of 3D geometry models for aircraft parts allows for direct generation of NC machining programs, enabling parts to be machined to nominal dimensions without shimming or final-hole-size drill jigs, with pre-drilled holes for precise alignment during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 2D drawings with tolerance ranges are used for manufacturing, then manufacturing variations can be accommodated, but assembly gaps and shimming are required
Solution Approach 1:
The patent transitions from 2D drawings with tolerance ranges to 3D CAD models with nominal dimensions. The 3D model defines the exact nominal geometry, and the NC machine uses this 3D data to machine parts to precise nominal dimensions without relying on 2D tolerance interpretations. This dimensional transition eliminates assembly gaps while maintaining manufacturing variability through statistical process control.
2Manufacturing precision
If parts are machined to nominal dimensions using 3D models, then assembly fit quality is enhanced, but manufacturing variation risk increases
Solution Approach 1:
The patent replaces the mechanical tolerance accommodation system (shims, gaps, adjustable fixtures) with a digital measurement and control system. Laser scanners capture actual part geometries, and this data feeds back to adjust NC machining programs, ensuring parts are machined to precise nominal dimensions. This substitution maintains reliability through digital measurement and control rather than mechanical tolerance buffering.
3Measurement precision
If traditional assembly fixtures and shimming are used, then alignment accuracy is achieved, but assembly time and costs increase
Solution Approach 1:
The patent makes the assembly process self-aligning through precise NC machining of mating surfaces and features to nominal dimensions. Parts are machined so precisely that they self-align during assembly without requiring external fixtures or shimming. The pre-drilled holes and mating features are positioned accurately through 3D model-based NC programming, enabling direct assembly of multiple sections without time-consuming alignment operations.
4Measurement precision
If multiple locating fixtures and drill jigs are used, then positioning accuracy is maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts the positioning and alignment functions from physical fixtures and drill jigs, transferring these functions to the 3D CAD model and NC machining program. The digital model contains all positioning information, and the NC machine automatically positions features according to the 3D model coordinates. This extraction eliminates the need for complex physical tooling while maintaining positioning accuracy through digital control.
Data Source
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AI summary
A method is provided for assembling an aircraft structure assembly (300) composed of a plurality of sections, and doing so without use of any shimming, locating fixtures or final-hole-size drill jigs. The method includes supporting the first and second frame sections (302, 304) on respective adjustable supports (310), and positioning the interconnecting frame section (306) therebetween. The method includes aligning first pre-drilled mating holes (316) in the interconnecting frame section (306) with first pre-drilled mating holes (314) in the first and second frame sections (302, 304), and installing fasteners (318) though the aligned, first pre-drilled mating holes (314, 316). The method includes positioning a structural mating section (308) relative to the first and second frame sections (302, 304) and interconnecting frame section (306) and aligning second pre-drilled mating holes (320) in the structural mating section (308) with second pre-drilled mating holes (322, 324) in at least one of the frame sections (302, 304, 306), and installing fasteners (326) through the aligned, second pre-drilled mating holes (320, 322, 324) to secure the structural mating section (308).