Re-tensionable Cable Bolt Sleeve with Anti-rotation Facets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current cable bolt systems for mine passage support face limitations such as loss of tension over time due to strata settlement or relaxation, inability to re-tension, and issues with false tensioning and kickback during installation.
Innovation Solution
A re-tensionable cable bolt apparatus featuring a sleeve with facets to prevent rotation and a resin-secured oversized cable portion, allowing for secure installation and later re-tensioning without bulky castings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional cable bolt system is installed, then initial tension support is provided, but the tension is lost over time due to strata settlement or relaxation and cannot be re-tensioned
Solution Approach 1:
The cable bolt system transitions from a static, fixed-tension design to a dynamic, adjustable-tension system. The retensionable nut and locking mechanism enable the bolt to be re-tensioned multiple times throughout its service life, adapting to changing ground conditions and maintaining reliable support.
Solution Approach 2:
The system allows changing the tension parameter over time through re-tensioning operations. The adjustable nut mechanism enables modification of the bolt's mechanical properties (tension force) without replacing the entire bolt, thereby extending its useful life and maintaining reliability.
2Ease of operation
If torque is applied to tension the cable, then installation is completed, but false tensioning occurs causing the cable to twist and kick back
Solution Approach 1:
The cable is pre-formed with a spiral configuration that opposes the twisting tendency during installation. This preliminary geometric feature counteracts the harmful rotational forces applied during torque application, preventing false tensioning and kickback while maintaining simple installation procedures.
Solution Approach 2:
The system combines the flexible cable with the rigid sleeve structure that has facets for engaging strata. This composite construction provides both the flexibility needed for installation and the structural rigidity to prevent rotation and ensure accurate tension application.
3Reliability
If an externally threaded tension head with anti-rotation keys is used, then rotation is prevented, but the structure becomes bulky and extends below the roof line
Solution Approach 1:
The anti-rotation function is extracted from the tension head and relocated to the lower end of the cable bolt system. The facets at the lower end engage with strata to prevent rotation, allowing the tension head to be simplified and reducing overall structure volume.
Solution Approach 2:
Instead of preventing rotation at the upper tension head (one-dimensional solution), the patent distributes anti-rotation engagement points along the length of the cable at the lower end (spatial redistribution). This dimensional approach prevents rotation while minimizing the volume of any single component.
4Reliability
If frequent intervals of bolts are placed throughout the mine passage, then face support coverage is improved, but installation cost increases
Solution Approach 1:
The cable portion of the bolt can be recovered and reused after extraction from one location. This recycling capability reduces material costs for frequent bolt installations, making it more economical to place bolts at frequent intervals for comprehensive face support coverage.
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 provides reliable, secure, and re-tensionable support for mine passage faces, preventing false tensioning and kickback, and allows for tension adjustment over time, enhancing installation reliability and safety.
Implementation Method 1
resin for securing the cable to the sleeve
Implementation Method 2
A plurality of facets along a peripheral portion of the lower end of the sleeve form corners adapted for engaging a stratum adjacent the borehole during installation
Data Source
AI summary
A re-tensionable cable bolt and related methods are provided. In one aspect of the invention, the bolt includes a sleeve for connecting or securing to a cable. The sleeve includes a lower end having a bore adapted for receiving a threaded shank for associating with a tension nut. A plurality of facets along a peripheral portion of the sleeve create corners that prevent the cable from rotating within the borehole during installation. The sleeve may be secured to the cable using resin, which forms another aspect of the invention.