Turbine Case Retention Hook Insert Repair

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Solution Overview

Problem

The wear between the retention hook and the ear of static vanes in gas turbine engines leads to unpredictable positioning, necessitating costly repair methods like welding or plasma spray.

Innovation Solution

A method involving the removal of worn material from the retention hook to create an enlarged recess, where a metal insert with radially inner and outer ledges and a connecting web is inserted, receiving the ear of the static vane, which can be circumferentially continuous or segmented.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If welding or plasma spray is used to repair the retention hook, then the wear damage is restored, but the repair cost becomes unduly expensive

Engineering Contradiction:

Improveretention hook durabilityVSAvoidrepair cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies this principle by using a replaceable insert rather than expensive welding or plasma spray repairs. The insert can be easily replaced when worn, providing a cost-effective solution compared to costly repair methods while maintaining the retention hook's functionality and durability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent applies this principle by combining the retention hook structure with a separate insert component. This composite approach allows the wear-prone area to be replaced independently through simple insertion and removal, avoiding the need for expensive repair processes while restoring the original durability.

Inventive Principle:

Principle #40Composite materials

2Ease of repair

If worn material is removed to create an enlarged recess for the insert, then the insert can be properly installed, but additional material removal is required

Engineering Contradiction:

Improveinsert installationVSAvoidmaterial removed from hook

Core Design Contradiction:

Ease of repairVSLoss of substance

Solution Approach 1:

The patent applies this principle by pre-forming the insert with dimensions that account for the worn material removal. The insert is designed to fit into the enlarged recess created by removing worn material, ensuring proper installation while minimizing unnecessary material removal beyond what is required to accommodate the insert.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the retention hook is repaired with traditional methods, then the wear damage is addressed, but the positioning predictability of the vane may still be compromised

Engineering Contradiction:

Improvevane positioning predictabilityVSAvoidrepair process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies this principle by dividing the retention hook into two separate components: the original hook structure and a replaceable insert. This segmentation allows the insert to be independently replaced when worn, ensuring that the vane positioning predictability is restored without requiring complex repair processes on the entire retention hook assembly.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9796055B2Turbine case retention hook with insert

Publication Date: 2017.10.24 RTX CORP

AI summary

A method of repairing a turbine engine case includes the steps of removing worn material from a retention hook in a casing, and inserting an insert into a recess within the hook.