Coaxial Panel Aperture Drilling for Canted Fastener Alignment

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Solution Overview

Problem

Existing methods for forming fastener apertures in aircraft propulsion system components, such as nacelle inner barrels, face challenges in precision and alignment due to the canted orientation of apertures relative to the panel surface, especially when replacing worn panels with new ones while reusing existing mounts.

Innovation Solution

A method and assembly involving a support structure, locator, and drill guide system that allows for angular offset drilling from both surfaces, ensuring accurate alignment and penetration through the panel's skin and cellular core without extending through the opposing surface, using a pilot tool to create a pilot aperture and a finishing tool to form a coupling aperture coaxial with the pilot aperture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a drill is used to form apertures at a canted angle relative to the panel surface, then the fastener alignment with the mount aperture is improved, but the drilling precision and alignment accuracy deteriorate

Engineering Contradiction:

Improvefastener alignmentVSAvoiddrilling precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The aperture formation process is divided into two separate operations: first drilling a pilot aperture along the canted first centerline, then drilling a second aperture along the perpendicular second centerline. This segmentation allows each drilling operation to use a simple perpendicular drill guide, maintaining high drilling precision while achieving the required canted angle alignment through the combination of the two apertures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pilot aperture is drilled first as a preliminary action to establish the correct canted angle orientation. This pilot aperture serves as a guide for the subsequent second aperture drilling, ensuring that the final fastener path aligns with the mount aperture while maintaining accurate drilling perpendicular to the panel surface

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If a single aperture is drilled through the entire panel thickness, then the fastener installation is simplified, but the structural integrity of the panel core is compromised

Engineering Contradiction:

Improvefastener installationVSAvoidpanel structural integrity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The single through-aperture is segmented into two separate apertures: a first aperture drilled to a controlled depth that does not extend through the entire panel thickness, and a second aperture drilled from the opposite surface to meet the first aperture. This segmentation preserves the structural integrity of the panel core while still allowing fastener installation through the combined aperture path

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of drilling completely through the panel, the first aperture is drilled to a partial depth that stops before penetrating the entire thickness. This partial action maintains structural integrity while the second aperture from the opposite surface completes the fastener path, achieving the necessary function without excessive material removal

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If a complex drilling apparatus is used to achieve precise angular offset drilling, then the aperture alignment accuracy is improved, but the device complexity increases

Engineering Contradiction:

Improveaperture alignment accuracyVSAvoiddrilling apparatus complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The complex angular offset drilling operation is segmented into two simple perpendicular drilling operations. Each operation uses a basic drill guide that aligns perpendicular to the panel surface, eliminating the need for complex angular positioning apparatus while achieving the desired canted angle aperture alignment through the combination of the two drilled apertures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of drilling the final aperture directly at the required canted angle, the method inverts the approach by drilling two separate apertures at simple perpendicular angles from opposite surfaces. The combination of these two perpendicular drilling operations achieves the canted angle alignment without requiring complex angular drilling apparatus

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS20230104975A1Tools and method for formation of an aperture in a panel

Publication Date: 2023.04.06 ROHR INC

AI summary

A method includes drilling a first aperture in a panel that extends between a panel first surface and a panel second surface. The first aperture projects into the panel along a first centerline from the panel first surface. The first centerline is angularly offset from the panel first surface by a first angle. A first tool is arranged with the panel. The first tool includes a support structure, a locator and a drill guide. The locator is mounted to the support structure and projects into the first aperture. The drill guide is mounted to the support structure and is arranged adjacent the panel second surface. A second aperture is drilled in the panel using the drill guide. The second aperture projects into the panel along a second centerline from the panel second surface to the first aperture. The second centerline is coaxial with the first centerline.