Quasi-Virtual Locate/Drill/Shim Process for Aircraft Assembly
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Solution Overview
Problem
Current methods for locating and shimming parts in large structures like aircraft or ships face challenges such as inherent reference tolerance, infeasibility of determinate assembly holes in complex structures, and inefficiencies in manually adjustable drill jigs that do not account for surface variations, leading to errors and increased costs.
Innovation Solution
A quasi-virtual locate/drill/shim process using metrology-directed DA hole placement with 3-D CAD tools and predictive shimming, employing adjustable drill bushings driven by 3-D measurement data and optical targets for accurate positioning and shim gap calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If determinate assembly holes are used for aligning parts, then parts can be held together with temporary fasteners, but inherent reference tolerance and tolerance build-up occur especially in large parts or assemblies
Solution Approach 1:
The patent replaces traditional mechanical drill jigs with a laser scanner-based measurement system. The laser scanner captures 3D coordinates of surface points, and a computer calculates precise hole locations based on these measurements, eliminating the mechanical tolerance accumulation inherent in physical jigs and fixtures.
Solution Approach 2:
The patent creates a digital copy of the part surface by scanning it with a laser scanner. This digital model is then used to calculate hole locations without requiring physical contact or mechanical fixtures, thereby avoiding the tolerance build-up that occurs in physical determination assemblies.
2Manufacturing precision
If monument locating jigs are used to hold parts in place, then parts can be positioned accurately, but the jigs are expensive to build and maintain
Solution Approach 1:
The patent replaces expensive mechanical monument locating jigs with a laser scanner and computer-based system. The laser scanner non-contactively measures surface geometry, and software algorithms calculate the precise positioning of components, eliminating the need for costly physical fixtures.
Solution Approach 2:
The part itself serves as the reference for positioning through its scanned surface geometry. The laser scanner captures the actual surface features, and the computer uses these measurements to determine hole locations directly from the part's own geometry, eliminating the need for external positioning fixtures.
3Adaptability or versatility
If manually adjustable drill jigs are used, then flexibility in positioning is achieved, but real-time positioning feedback is required and surface variation is not accounted for
Solution Approach 1:
The patent replaces manual adjustment mechanisms with an automated laser scanning and computer calculation system. The laser scanner captures surface variation, and the computer automatically calculates corrected hole locations that account for the actual surface geometry, eliminating the need for manual positioning and feedback loops.
Solution Approach 2:
The patent performs preliminary measurement of the surface geometry using a laser scanner before hole placement. This advance knowledge of surface variation allows the computer to calculate precise hole locations that compensate for manufacturing tolerances and surface irregularities before the drilling operation begins.
4Productivity
If DA holes are placed ahead of time on built-up structures, then assembly is simplified, but the correct location is not yet known for complex structures
Solution Approach 1:
The patent performs preliminary scanning and calculation to determine the correct hole locations before drilling. The laser scanner captures the actual surface geometry, and the computer calculates precise hole positions based on these measurements, allowing holes to be placed accurately without requiring pre-positioned fixtures.
Solution Approach 2:
The patent replaces physical trial-and-error positioning with a laser-based measurement and computer-based calculation system. This allows hole locations to be determined accurately and efficiently without requiring physical fixtures or iterative adjustment.
Data Source
AI summary
A method for determining characteristics of a shim fittable between first and second bodies, comprising: (a) placing optical targets in respective sets of holes in the first and second bodies; (b) scanning respective surfaces of the first and second bodies using a three-dimensional scanner to acquire point cloud scan data, measured hole vector data and other discrete feature data; (c) processing the point cloud scan data, measured hole vector data and other discrete feature data to derive first deviation values representing the deviation of the surface of the first body from a nominal surface of the first body and second deviation values representing the deviation of the surface of the second body from a nominal surface of the second body; (d) correlating the first deviation values with the second deviation values based on a best fit position of the first body relative to the second body; and (e) computing shim gap values based on the correlated first and second deviation values.