Cable Bolt Bulbous Portion Segmented Ring Design
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Solution Overview
Problem
Existing cable bolts face issues with protuberance collapse during tensioning, leading to reduced effectiveness, and previous solutions like ball bearings are expensive, unreliable, and create stress concentrations, making it difficult to automate their placement and maintain the integrity of the cable.
Innovation Solution
A cable bolt design featuring flexible steel filaments around a central member with spaced bulbous portions containing segmented rings that engage the filaments, allowing for non-collapsible protrusions without plastic deformation, and a method to form these protrusions using torsion and a spreading tool to insert spacers between the filaments and central member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ball bearings are inserted into protuberance cavities to prevent collapse, then the likelihood of protuberance collapse is reduced, but the manufacturing cost increases and reliability decreases due to ball bearings being pushed out
Solution Approach 1:
The protuberance is segmented into a modular structure comprising a central hollow strand and multiple cable strands arranged around it. This segmentation allows each component to be independently manufactured and assembled, eliminating the need for complex ball bearing insertion processes while maintaining structural integrity and preventing collapse during tensioning.
2Reliability
If ball bearings are used to prevent protuberance collapse, then stability is improved, but stress concentration occurs on cable strands creating loads that reduce ultimate tensile strength by up to 25%
Solution Approach 1:
The harmful ball bearing component is completely removed from the system. Instead, a hollow central strand is used that provides structural support without creating stress concentrations on the cable strands, thereby maintaining the cable's ultimate tensile strength while still preventing protuberance collapse.
Solution Approach 2:
The hollow central strand acts as an intermediary element that provides the necessary structural support and prevents protuberance collapse without directly contacting or concentrating stress on the cable strands. This mediator distributes loads evenly throughout the cable structure.
3Reliability
If ball bearings are inserted to prevent collapse, then protuberance stability is improved, but the process becomes difficult to automate
Solution Approach 1:
The hollow central strand is pre-formed during cable manufacturing before the protuberances are created. This preliminary action integrates the support structure into the cable fabrication process itself, allowing for complete automation without requiring separate, complex ball bearing insertion steps.
4Ease of operation
If protuberances are made collapsible to allow tensioning, then cable installation is easier, but the cable's effectiveness is reduced
Solution Approach 1:
The structural parameters of the protuberance are changed by incorporating the hollow central strand and modular cable strand arrangement. This configuration maintains protuberance rigidity and effectiveness during tensioning while still allowing for proper cable installation through standard procedures.
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 solution prevents protuberance collapse under tension, maintains the cable's integrity, and allows for automated manufacturing of non-collapsible bulbs, enhancing load transfer and anchorage without reducing the cable's tensile strength.
Implementation Method 1
the filaments are forced apart by applying torsion to the filaments
Implementation Method 2
releasing the parted filaments to return against the spacer to form a bulbous portion
Data Source
AI summary
A cable bolt comprising a plurality of flexible steel filaments formed around a central member, the cable bolt having spaced bulbous portions along the length of the bolt each bulbous portion defining a cavity containing a segmented ring that surrounds the central member to engage the filaments of the bulbous portion.