Rock Bolt Catch Structure to Arrest Tendon Ejection
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Solution Overview
Problem
Existing rock bolts face safety issues due to rod ejection during high loading, which can lead to personnel and equipment hazards, and current arrestment arrangements either complicate assembly or reduce the machine torque available for expanding the expander mechanism.
Innovation Solution
A rock bolt design featuring a catch, typically a ring, fixed within the tube between the tendon projection and the trailing end, allowing easier assembly by inserting components through the trailing end, and utilizing a catch with an opening that prevents the tendon projection from passing through, thereby arresting ejection by engaging the tendon projection at an angle, reducing the available space and enhancing arrestment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional arrestment arrangement (sleeve on reduced diameter rod end) is used, then rod ejection is arrested, but assembly becomes more complex and machine torque for expander expansion is reduced
Solution Approach 1:
The invention extracts the arrestment function from the complex traditional sleeve-and-reduced-diameter-rod-end arrangement and implements it through a simple catch with an opening that engages the tendon projection. This simplifies the overall device structure while maintaining the essential arrestment function.
Solution Approach 2:
Instead of having the rod end reduce in diameter to fit a sleeve (traditional approach), the invention inverts the approach by having a fixed catch with an opening that the tendon projection must engage. The tendon projection cannot pass through the opening, providing arrestment without requiring rod diameter reduction or complex sleeves.
2Ease of operation
If a fixed nut and threaded rod arrangement is used to activate the expander mechanism, then the expander can be activated by rotating the nut, but the rod may be ejected during high loading
Solution Approach 1:
The invention segments the rod into portions with different functions: a first portion for activation of the expander mechanism and a second portion with a projection for arrestment. This segmentation allows the rod to serve multiple purposes while preventing ejection through the engagement of the projection with the catch.
Solution Approach 2:
The catch acts as an intermediary element between the rod and the tube, providing arrestment without interfering with the activation mechanism. The catch with its opening engages the tendon projection to prevent ejection while allowing the rod to move freely during activation.
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 design effectively arrests the ejection of the tendon portion, enhancing safety by preventing complete ejection and allowing easier assembly, while maintaining the ability to expand the expander mechanism, thus providing improved safety and operational efficiency.
Implementation Method 1
the expander mechanism is activated once the rock bolt has been inserted into the hole to increase the frictional engagement of the tube with the facing wall of the hole
Implementation Method 2
Movement of the anchor arrangement will also increase the tensile load on the rod, which can cause the rod to elongate. Rod elongation beneficially absorbs dynamic loading on the bolt
Data Source
Figure 1~2
Figure 3~6
Figure 7~9
AI summary
A rock bolt 40 comprising: an elongate, generally circular tube 41, the tube having a leading end 13 and a trailing end (42), an expander mechanism 15 disposed within the tube in the region of the leading end 13, an elongate tendon 44 disposed longitudinally within the tube 41 and in connection at or towards a first end of the tendon 44 with the expander mechanism 15 and in connection at or towards a second and opposite end of the tendon 44 with an anchor arrangement 46 positioned at the trailing end 42 of the tube 41, the tendon 44 having a projection 56 that extends radially and that is positioned between the expander mechanism 15 and the anchor arrangement 46 and the tube 41 having a catch 58, the catch 58 having an opening 62 through which the tendon 44 extends and the projection 56 having a radial dimension too great to pass through the opening 62, wherein the catch 58 is fixed in position within the tube 41 between the tendon projection 56 and the trailing end 42 of the tube 41.