Locked Securing Stud Assembly With Torque-Limiting Wrench

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Solution Overview

Problem

Existing securing stud assemblies for turbines face challenges in applying sufficient tightening torque without damaging parts, particularly when studs with non-uniform gaps or larger diameters are involved, and risk excessive screwing that can damage captive nuts.

Innovation Solution

A locking wrench with a main body featuring a non-circular bore and a projecting portion that allows limited stud rotation, preventing excessive screwing and distributing torque to resistant flange and stud parts, while being easily adjustable and positioned with separated journals to avoid damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a locking wrench is used to apply tightening torque to the stud, then the assembly rigidity is improved, but the risk of damaging the captive nut or flange increases due to excessive torque application

Engineering Contradiction:

Improveassembly rigidityVSAvoiddamage to captive nut or flange

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The locking wrench acts as an intermediary device between the tightening tool and the stud. It transmits the tightening torque while distributing the forces to resistant parts of the flange and stud through its specific geometry, preventing concentration of stress that could damage the captive nut or flange.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The locking wrench is designed with a specific shape that inherently limits the maximum torque that can be applied. The geometry of the wrench creates a mechanical stop that prevents excessive tightening before damage can occur, cushioning against potential harm in advance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Strength

If the stud has a larger diameter to ensure sufficient tightening force, then the assembly strength is improved, but the risk of excessive screwing and damaging the captive nut increases

Engineering Contradiction:

Improveassembly strengthVSAvoidexcessive screwing damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The locking wrench serves as a mediator that controls the interaction between the stud and the assembly. Its design ensures that even with a larger diameter stud, the tightening force is distributed appropriately and excessive screwing is prevented, protecting the captive nut from damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple wrenches with different widths are used to accommodate non-uniform stud gaps, then the adaptability is improved, but the device complexity and inventory requirements increase

Engineering Contradiction:

Improveaccommodation of non-uniform gapsVSAvoidnumber of wrench types

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The locking wrench is designed with a universal geometry that allows it to be used on studs with varying gaps. The specific shape of the wrench enables it to accommodate different stud positions and orientations without requiring multiple specialized tools, reducing inventory complexity while maintaining adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10900382B2Assembly comprising a locked securing stud

Publication Date: 2021.01.26 SAFRAN AIRCRAFT ENGINES SAS

AI summary

An assembly includes a securing stud held by a locking key that rotates with the stud and is provided with bearing surfaces for sitting on an edge of one of the parts to be assembled.