Internal Chamfering Device for Layered Structures

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Solution Overview

Problem

Conventional methods face challenges in efficiently and cost-effectively deburring and chamfering drilled fastener openings in titanium and carbon fiber-reinforced plastic parts, particularly in maintaining fatigue strength and requiring disassembly, which increases time and expense.

Innovation Solution

An internal chamfering device with a cutting assembly and GMR sensors is used to locate and remove entry/exit burrs without separating layers, enhancing fatigue strength by creating a material interface chamfer through simultaneous deburring and chamfering of fastener openings in layered structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional drilling and deburring methods are used, then burrs are removed from fastener openings, but disassembly is required which increases time and expense

Engineering Contradiction:

Improvedeburring efficiencyVSAvoiddisassembly time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The chamfering tool is inserted through the fastener opening and nested within the layered structure, allowing internal chamfering without disassembly. The tool bit extends through the opening to work on both entry and exit burrs from the interior side of the layers

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The chamfering process is divided into separate stages: first chamfering the entry side, then the exit side, with the tool bit being extended and retracted through the opening. This allows sequential working of different surfaces without removing the layers

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If disassembly is performed to access internal surfaces for chamfering, then complete deburring is achieved, but cost and time increase

Engineering Contradiction:

Improvechamfering completenessVSAvoidprocess cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The fastener opening itself serves as the access pathway for the chamfering tool. The existing opening allows the tool bit to reach internal surfaces without requiring additional disassembly or creation of new access points

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of accessing the interior from the exterior sides of the layers, the chamfering tool approaches the burrs from the interior side through the opening, working outward to remove burrs at both entry and exit surfaces

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If burrs are not removed, then assembly time is reduced, but fatigue strength of the part decreases

Engineering Contradiction:

Improveassembly speedVSAvoidfatigue strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

Chamfering is performed as a preliminary step before final assembly, removing burrs in advance to prevent fatigue issues. The tool bit is positioned and extended to chamfer surfaces before the fastener is fully installed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cutting mechanism uses a rotating tool bit with cutting edges that mechanically remove burr material through abrasion and cutting actions, replacing less effective mechanical methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9517511B1Internal chamfering device and method

Publication Date: 2016.12.13 THE BOEING CO

AI summary

A method of forming an opening in a layered structure includes providing a layered structure including a first layer and a second layer and a near-zero gap interface defined between the first layer and the second layer; providing an opening through the layered structure such that the opening extends through the first layer and the second layer; and working simultaneously the opening in the fay surface of the first layer and the opening in the fay surface of the second layer without separating the first layer and the second layer. An internal chamfering device is also disclosed.