Multi-Color Direct Tension Indicating Washer Visual Feedback
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Solution Overview
Problem
Standard direct tension indicating (DTI) washers rely on labor-intensive feeler gauge inspections, which are prone to human error and variability, and lack clear visual cues for determining adequate compression, making it difficult to ensure proper bolt tension across installations.
Innovation Solution
A direct tension indicating washer with a first surface featuring bumps and a second surface with discrete indentations containing indicating materials of different colors, where the colors (green and red) indicate whether the desired bolt tension has been achieved, with the green color signaling to continue tightening and the red color indicating it's time to stop, utilizing a channel for the material to emerge at the outer edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard DTI washers are used with feeler gauge inspection, then bolt tension can be determined, but the inspection process is labor intensive and prone to human error
Solution Approach 1:
The patent applies color-coded indicating materials (green and red) that emerge from the DTI washer to provide immediate visual feedback on bolt tension status. Green indicates proper tension is achieved, while red indicates over-tensioning. This eliminates the need for labor-intensive feeler gauge inspections and reduces human error by providing unambiguous visual cues that are independent of language interpretation.
2Reliability
If feeler gauge inspection is used for all DTIs, then adequate compression can be determined, but the process is time consuming and subject to judgment variability
Solution Approach 1:
The DTI washer performs self-inspection by automatically displaying its tension status through color-coded material emergence. The washer itself provides the indication without requiring external inspection tools or subjective judgment, thereby eliminating inspection time variability and improving consistency across all bolts.
3Difficulty of detecting and measuring
If standard DTI appearance is used, then the washer remains simple in design, but it is difficult to distinguish compressed from uncompressed state at a distance
Solution Approach 1:
The patent incorporates color-coded indicating materials (green and red) within the DTI washer structure. When the washer is compressed to the proper tension, green material emerges; when over-compressed, red material emerges. This color-coding system provides clear visual distinction between different tension states from a distance, while maintaining relative structural simplicity through the use of embedded indicating materials and channels.
4Loss of information
If SQUIRTER DTI with single color elastomeric material is used, then visual indication of proper tension is improved, but it cannot indicate when a second tension level has been reached
Solution Approach 1:
The patent divides the indicating system into multiple color-coded segments (green and red materials) that represent different tension levels. The green material indicates when proper minimum tension is achieved, while the red material indicates when a second, higher tension level has been reached. This segmentation allows the single DTI washer to convey multiple tension status messages without requiring multiple separate indicators.
Solution Approach 2:
Different regions of the DTI washer contain different indicating materials with distinct color properties. The green indicating material is positioned to emerge at specific compression levels, while red material is positioned to emerge at higher compression levels. This local differentiation of material properties allows the system to provide nuanced tension information across different compression states.
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 solution provides a more consistent and intuitive visual indication of proper bolt tension, reducing human error and ensuring all bolts are correctly tensioned, as the emergence of red material clearly signals the installer to stop tightening, thereby achieving consistent and reliable bolt tensioning.
Implementation Method 1
when the DTI protrusion compresses parallel to the development of bolt tension, eventually the highly visible elastomeric material finds its way out to the outer diameter of the DTI through a small stamped channel
Data Source
AI summary
A direct tension indicating washer includes a first surface having a plurality bumps formed thereon; a second surface having a plurality of discrete indentations, each indentation formed opposite one of said protuberances; an indicating material positioned in at least one indentation, the indicating material including an indicating material having a first color and an indicating material having a second color; and a channel leading from the at least one indentation to an outer edge of said direct tension indicating washer.