Portable Hot-Air Tool for Rotor Blade Cuff Ring Bonding

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Solution Overview

Problem

The existing methods for replacing rings on a rotorcraft rotor's clevis require long downtime due to the slow polymerization cycle of room temperature adhesives, leading to prolonged unavailability of the rotorcraft.

Innovation Solution

A portable tool that uses a heater, diffuser, and temperature control system to apply hot air for rapid polymerization of adhesives, allowing for quick bonding of rings to the clevis without heating the sleeve, thus reducing downtime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If room temperature adhesive polymerization is used to bond rings to clevis, then the sleeve is not damaged by heating, but the polymerization cycle takes about seven days causing prolonged rotorcraft unavailability

Engineering Contradiction:
Improvepolymerization temperatureVSAvoidpolymerization cycle duration
Core Design Contradiction:
TemperatureVSLoss of time

Solution Approach 1:

The heating process is segmented into controlled zones: the adhesive layer and ring are heated to accelerate polymerization, while the sleeve remains at ambient temperature. This spatial segmentation allows different temperature regimes in different regions of the system, resolving the contradiction between fast polymerization and sleeve protection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating a localized heating environment specifically at the adhesive-rink interface. The heating means are positioned to concentrate thermal energy only where needed for polymerization, while the surrounding sleeve material remains cool. This localized approach enables rapid curing without subjecting the entire assembly to damaging temperatures.

Inventive Principle:
Principle #3Local quality

2Productivity

If heating is applied to accelerate adhesive polymerization, then the rotorcraft availability improves, but the sleeve may be damaged by significant heating

Engineering Contradiction:
Improvering replacement speedVSAvoidthermal damage to sleeve
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system is divided into thermal zones where the adhesive and ring experience high temperatures for rapid polymerization, while the sleeve remains in a cool zone. This segmentation allows productive heating without transmitting harmful thermal energy to the sleeve structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adhesive layer acts as an intermediary that receives thermal energy and undergoes rapid polymerization, while the heating means are designed to deliver energy selectively to the adhesive-rink interface. This intermediary approach enables fast curing without directly heating the sleeve, thus maintaining productivity while avoiding thermal damage.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The tool enables the replacement of rings in a short duration, with adhesive polymerization occurring in approximately one hour instead of seven days, minimizing rotorcraft immobilization and ensuring the sleeve's integrity is not compromised.

Implementation Method 1

a heater, for example a heater marketed under the reference HOT GUN 1000

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

a diffuser defining an internal space supplied with hot air by said heater via a conveying duct

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2301843B1Portable tool for glueing a bush to a trunnion yoke of a rotor blade cuff and method of glueing this trunnion yoke
Publication Date: 2012.08.29 EUROCOPTER FRANCE SA
  • EP2301843B1 patent drawingFigure 1~2
  • EP2301843B1 patent drawingFigure 3~4

AI summary

The tool has a diffuser (200) defining an internal space supplying hot air by a heater (100) through a supply duct (300) for heating rings to be glued. Temperature sensors (501, 502) determine temperature of the ring. A control unit controls the heater based on the information from the sensors. Ring supports (401, 402) are arranged at ends (211, 212) of the diffuser, respectively, where the each ring support has a plate that closes the ends of the diffuser. Each ring support has a path that is integrated to the plate. An independent claim is also included for a method for gluing rings at flanges of a clevis of a sleeve of a blade.