Cable Tie Pawl Shelf Support Prevents Roll Out
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Solution Overview
Problem
Current fasteners, particularly cable ties, face issues with 'pawl roll out' failure under high loop tensile force, which requires increased material usage or user fatigue to enhance loop tensile strength, as existing designs either increase pawl size or strap tooth depth.
Innovation Solution
A fastener assembly with a novel pawl design featuring a shelf support within the head portion, which engages with the strap teeth to prevent 'pawl roll out' and enhance loop tensile strength without additional material or increased user force, utilizing a molded design with enhanced physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pawl size is increased to prevent pawl roll out and increase loop tensile strength, then the reliability and strength improve, but the device complexity and material usage increase
Solution Approach 1:
The patent introduces a shelf support feature that extends from the head portion in a direction perpendicular to the main body of the fastener, creating a new spatial dimension for support. This shelf extends between the inner walls of the head portion and provides a bearing surface for the pawl, preventing rotational movement without requiring an increase in the overall size of the pawl feature itself.
Solution Approach 2:
The shelf support feature acts as an intermediary element between the head portion and the pawl. It provides a dedicated bearing surface that mediates the interaction between these components, distributing loads and preventing direct stress concentration on the pawl that would lead to roll out failure.
2Strength
If the strap tooth depth is increased to enhance loop tensile strength, then the strength improves, but the ease of operation deteriorates due to increased user force requirement
Solution Approach 1:
The shelf support feature is pre-configured within the head portion to provide immediate support to the pawl during operation. This preliminary structural arrangement ensures that the pawl is supported before and during the cinching action, preventing distortion and maintaining engagement without requiring excessive user force.
3Reliability
If additional material is used to increase pawl size for preventing roll out, then the reliability improves, but the manufacturing cost increases
Solution Approach 1:
The head portion is segmented into functional zones: the main body and the shelf support feature. This segmentation allows the shelf to be optimized specifically for its support function without increasing the material usage of other components. The shelf is positioned to provide maximum support with minimal material.
Solution Approach 2:
The shelf support feature concentrates material and structural reinforcement specifically where needed - at the location where the pawl requires support to prevent roll out. This local quality approach ensures that additional material is used only in the critical region rather than uniformly throughout the entire fastener.
Data Source
AI summary
A fastener assembly having a unique pawl design for the head portion of a fastener assembly. The fastener assembly may be a cable tie that includes a head portion having a pawl that includes a primary pawl tooth, at least one set of secondary pawl teeth, and a shelf support feature for pawl. The fastener assembly of the present invention prevent pawl roll out which is a failure that currently occurs with fastener assembly currently available in the market place.