Temporary Fastener Drive Nut Axial Length Encoding for Torque Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing temporary fastening systems in the aeronautical industry face challenges in accurately determining the appropriate tightening torque for staples of different diameters, leading to potential degradation or excessive play in assembled structures, and current solutions like color codes or multiple hardware sets are cumbersome and prone to human error.

Innovation Solution

A family of temporary fasteners with drive nuts of identical radial but varying axial dimensions, allowing an installation tool to automatically detect the nut length and adjust the tightening torque accordingly, combined with visual identifiers for operator recognition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If manual adjustment of tightening torque is used for staples of different diameters, then the device can be simple, but human error increases and measurement precision deteriorates

Engineering Contradiction:
Improvedevice complexityVSAvoidtightening torque precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The staple itself serves as the identifier through its drive nut length. The system automatically determines the appropriate tightening torque by measuring the axial length of the drive nut, eliminating the need for manual identification and adjustment by the operator. This self-identifying mechanism resolves the contradiction by making the system self-servicing rather than relying on human judgment.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical adjustment with an automated measurement and control system. A measurement device quantifies the drive nut length, and this information automatically controls the tightening torque application, substituting human-operated mechanical adjustment with an instrumented, automated system that eliminates human error.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If color codes or identification signs are used on staples, then diameter identification is possible, but the system becomes cumbersome and human error increases

Engineering Contradiction:
Improvefastener identification easeVSAvoididentification reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

Instead of using external identification markers like color codes, the patent uses a fundamental parameter change - the axial length of the drive nut - as the identification feature. This geometric parameter directly correlates with staple diameter and is inherently tied to the fastener's function, making identification reliable and eliminating the need for separate marking systems.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts the identification function from separate markers (color codes, signs) and integrates it directly into the fastener's structural component - the drive nut. By making the drive nut length itself the identifier, the system eliminates redundant identification elements and reduces complexity while improving reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If multiple dedicated installation tools with different torque settings are used, then each staple type can be optimized, but hardware quantity and device complexity multiply

Engineering Contradiction:
Improvetightening torque precisionVSAvoidinstallation tool complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent creates a universal installation device that can handle multiple staple types through a single tool. The device measures the drive nut length of any inserted staple and automatically adjusts the tightening torque accordingly, making one tool perform the function of multiple dedicated tools while maintaining precision for each staple type.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The installation device incorporates dynamic adaptability by measuring the drive nut length and automatically adjusting the tightening torque parameter based on the detected staple type. This dynamic adjustment capability allows a single device to optimize performance for different staple diameters without requiring multiple fixed-setting tools.

Inventive Principle:
Principle #15Dynamics

4Adaptability or versatility

If the same installation device is used for different diameter staples, then device quantity is reduced, but manual adjustment increases human error risk

Engineering Contradiction:
Improvedevice adaptabilityVSAvoidtightening torque reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the measurement device quantifies the drive nut length, and this measurement information feeds back to automatically control the tightening torque application. This closed-loop feedback system ensures that the correct torque is applied for each staple type, eliminating manual adjustment errors while maintaining device versatility.

Inventive Principle:
Principle #23Feedback

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 system ensures accurate and automatic adaptation of tightening torque based on the fastener diameter, reducing human error and ensuring consistent quality in temporary assemblies.

Implementation Method 1

a family of at least two temporary fasteners of different diameters and whose drive nuts have an identical radial outer dimension and a different axial outer dimension

Methodology Applied
Scientific EffectGeometric encoding:

Implementation Method 2

a mechanism movable relative to the body, the mechanism comprising a threaded rod arranged coaxially with the body, one end of the rod being extended by the clamp, the mechanism further comprising a control nut mounted on another end of the rod

Methodology Applied
Scientific EffectScrew mechanism: Screw

Implementation Method 3

a body provided with a bearing surface capable of coming into contact with a front face of the structures to be assembled, at least one clamp intended to pass through the holes and provided with a hooking nose capable of being applied against a rear face of the structures to be assembled

Methodology Applied
Scientific EffectMechanical compression: Compression

Data Source

PatentEP2669051B1Family of temporary fasteners and device for applying such fasteners
Publication Date: 2019.12.04 LISI AEROSPACE
  • EP2669051B1 patent drawingFigure 1~2
  • EP2669051B1 patent drawingFigure 3~5

AI summary

The family has a cylindrical body (101) comprising a bearing face (102) in contact with a front face of structures to be assembled. An extended half-clip (103) is passed through drilled holes and provided with a hooking spur (104). A mechanism is moved relative to the body, and includes a threaded rod (105) placed coaxially to the body. The rod has an end connected to the clip. The mechanism has control nuts (107) screwed onto the rod. Temporary fasteners (100) have different diameters, and the nuts have identical outer radial dimension and a different outer axial dimension i.e. length (116). An independent claim is also included for an assembly for installing temporary fasteners.