Threaded Fastener Installation Using Ultrasonic Tension Feedback
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Solution Overview
Problem
Existing methods for installing threaded fasteners do not accurately account for variations in applied tension caused by actual tightened thickness and overheating, leading to inconsistent axial tension in screws.
Innovation Solution
A method that involves determining the thickness of the structure to be tightened and adjusting the target value of a parameter representative of axial tension based on both the thickness and geometrical characteristics of the fastener, while also monitoring and adjusting for temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed target tension is applied to the screw regardless of structure thickness, then the installation process is simple, but the actual axial tension varies with different tightened thicknesses
Solution Approach 1:
The patent implements dynamic adjustment of the target parameter value based on the measured thickness of the structure. The system transitions from a fixed target tension approach to a dynamic target value that adapts to different structure thicknesses, ensuring consistent axial tension across varying applications
Solution Approach 2:
The patent employs feedback control by measuring the actual structure thickness and using this information to adjust the target parameter value during the installation process. The system continuously monitors and adjusts parameters to achieve the desired axial tension based on real-time thickness measurements
2Adaptability or versatility
If the nut is tightened on the screw to join structures of different thicknesses, then versatility is improved, but the screw elongation varies and affects the applied tension
Solution Approach 1:
The patent changes the target parameter value based on the measured structure thickness. Instead of maintaining a fixed target tension, the system adjusts the target parameter dynamically according to the specific thickness being tightened, allowing versatile application across different structure thicknesses while maintaining precise axial tension control
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
This method ensures that the axial tension in screws is accurately controlled, correcting for variations due to thickness and temperature, thereby ensuring consistent and reliable fastening.
Implementation Method 1
simultaneously transmitting ultrasonic waves into the fastener and receiving reflected ultrasonic waves for the measurement of a first parameter representative of a variation in said waves
Implementation Method 2
measuring the variation in the time-of-flight of ultrasonic waves transmitted and received in the screw, the time-of-flight providing an indirect measure of the axial tension in the screw
Implementation Method 3
tightening the nut on the screw heats up the screw, the temperature increase amplifies the screw's elongation and therefore reduces its axial tension
Data Source
AI summary
A method for the installation of a threaded fastener (10) in a structure, the threaded fastener comprising a screw (20) and a nut (28), the method comprising the following steps:a) inserting the screw into the structure, and tightening the nut onto the screw,b) simultaneously transmitting/receiving ultrasonic waves into/from the fastener for the measurement of a parameter representative of a variation in said waves, said first parameter providing an indirect measurement of an axial tension in the screw,c) stopping the screwing when a target value for the first parameter is reached.The process further comprises determining the thickness of the structure to be tightened, and determining the target value of the first parameter in accordance with the thickness of the structure to be tightened and the geometrical characteristics of the fastener (10).