Rock Bolt End Coupling for Torque Transfer Without Protruding Tail
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Solution Overview
Problem
Conventional rock bolt systems face challenges in rotating the bolt to mix resin or grout and achieve adequate tensioning, especially when there is little or no tail protruding from the rock face, making it difficult to effectively consolidate rock strata in mining and tunneling operations.
Innovation Solution
An end coupling with a shaft having an external thread, featuring a body with a first passage portion for threadingly engaging the rock bolt and a second passage portion with a drive receiving portion to impart rotation, allowing for torque transfer and tensioning without a protruding drive end, enabling secure and safe coupling with minimal bore enlargement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the rock bolt has no tail protruding from the rock face, then the surface profile is minimized, but it becomes difficult to rotate the bolt to mix resin or grout and to tension the bolt
Solution Approach 1:
The coupling device is segmented into distinct functional zones: a first passage portion for receiving and engaging the rock bolt, and a second passage portion for receiving rotation and tensioning tools. This segmentation allows the bolt end to be contained within the first passage while tool access is provided through the second passage, resolving the contradiction between minimal surface profile and ease of operation.
Solution Approach 2:
The coupling device acts as an intermediary component between the rock bolt and the tooling system. It provides threaded engagement with the bolt shaft while simultaneously providing a drive receiving portion for external tools, thereby mediating between the contained bolt end and the external tensioning/rotation operations without requiring bolt tail protrusion.
2Reliability
If a conventional expansion assembly or resin bonding is used, then the rock bolt can be anchored, but adequate rotation and tensioning cannot be achieved when the tail does not protrude
Solution Approach 1:
The coupling device merges multiple functions into a single integrated component: it combines the anchoring function (through threaded engagement with the bolt shaft), the rotation function (through the drive receiving portion that accepts rotation tools), and the tensioning function (through the same drive receiving portion that accepts tensioning tools). This merging resolves the contradiction by providing all necessary functions without requiring separate protruding components.
Solution Approach 2:
The coupling device is designed as a multi-functional component that serves multiple purposes: it anchors the rock bolt through threaded engagement, provides rotation capability through the drive receiving portion, and enables tensioning through the same drive receiving portion. This universality allows a single component to address multiple requirements that would otherwise need separate protruding elements.
3Ease of operation
If the rock bolt tail protrudes to allow tool access, then rotation and tensioning are easier, but the surface profile is increased and safety is reduced
Solution Approach 1:
The coupling device implements a nested structure where the first passage portion contains the rock bolt shaft, and the second passage portion contains the tooling operations. This nesting allows tool access and operations to be performed within the confines of the coupling device body, eliminating the need for bolt tail protrusion while maintaining ease of operation.
4Ease of manufacture
If minimal bore enlargement is used, then installation is simpler, but secure coupling is more difficult to achieve
Solution Approach 1:
The coupling device applies local quality by concentrating the engagement and securing functions within the first passage portion where it threads onto the bolt shaft, while the second passage portion maintains a minimal profile for tool access. This localized functional distribution allows secure coupling to be achieved through precise threaded engagement without requiring extensive bore enlargement elsewhere in the system.
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 end coupling facilitates efficient rotation and tensioning of rock bolts, ensuring effective rock strata consolidation with a low profile design that minimizes surface protrusion and allows for secure attachment of additional components like hangers or load testers, enhancing safety and operational efficiency in mining applications.
Implementation Method 1
a first passage portion extending along the axis from the leading end; the first passage portion including a first thread portion to threadingly engage the external thread on the shaft of the rock bolt
Implementation Method 2
a second passage portion extending along the axis from the trailing end; the second passage portion including a drive receiving portion arranged to be engaged with a drive inserted into the second passage portion via the trailing end to impart rotation to the coupling about the axis
Data Source
AI summary
An end coupling for a rock bolt having a shaft having an external thread, the coupling having an axis and the coupling comprising a body having a leading end and a trailing end spaced apart along the axis, a first passage portion extending along the axis from the leading end; a second passage portion extending along the axis from the trailing end; the first passage portion including a first thread portion to threadingly engage the external thread on the shaft of the rock bolt; the second passage portion including a drive receiving portion arranged to be engaged with a drive inserted into the second passage portion via the trailing end to impart rotation to the coupling about the axis.