Rock Bolt Anchor Assembly With Rotating Expansion Element

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Solution Overview

Problem

Existing thread-based rock bolt expansion mechanisms face high internal friction within movable parts, making it difficult to initiate expansion and limiting the expansion range, which is crucial for effective anchoring in both harder and softer grounds.

Innovation Solution

An anchoring device with a rotatable anchoring element and abutment element that transfers a pulling force to rotate the anchoring element outward, engaging it with the bore hole wall, allowing for a larger expansion range and smoother anchoring process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thread-based expansion mechanism is used, then the rock bolt can be anchored in the bore hole, but the internal friction between movable parts is greater than the initial rotational friction, making it difficult to initiate expansion

Engineering Contradiction:
Improveanchoring reliabilityVSAvoidexpansion initiation difficulty
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention extracts and eliminates the threaded connection between the expansion element and the rock bolt. Instead, a bearing surface is provided on the rock bolt that directly engages with the expansion element, removing the problematic thread interface that generated excessive internal friction and prevented easy initiation of expansion.

Inventive Principle:
Principle #2Taking out (Extraction)

2Length of moving object

If the expansion range is increased to facilitate insertion in the bore hole, then the anchoring strength may be compromised

Engineering Contradiction:
Improveexpansion rangeVSAvoidanchoring strength
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The invention transitions from a single-dimensional axial expansion to a two-dimensional radial expansion mechanism. The expansion element rotates outward from the rock bolt axis, enabling the anchoring device to achieve both large expansion range for easy insertion and maintained anchoring strength through the radial engagement with the bore hole wall.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enables efficient anchoring in various ground conditions by increasing the expansion ratio and reducing stress concentrations, facilitating easy installation and verification of anchoring through a single pulling action, suitable for both harder and softer grounds.

Implementation Method 1

The engagement of the wedge with the bore hole wall will create a friction fit anchoring the rock bolt in the bore hole

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4700209A1Rock bolt anchor assembly
Publication Date: 2026.02.25 SANDVIK MINING & CONSTRUCTION AUSTRALIA (PRODUCTION SUPPLY) PTY LTD
  • EP4700209A1 patent drawingFigure 1a~2b
  • EP4700209A1 patent drawingFigure 3a~4b
  • EP4700209A1 patent drawingFigure 4c~5b

AI summary

An anchoring device 100 for a rock bolt 130 arranged for installation within a bore hole, comprising: an anchoring element 110 configured to be rotatably connected to the rock bolt 130, and to be arranged in a first state allowing the rock bolt 130 to be inserted into the bore hole, and an abutment element 120 arranged to engage with the anchoring element 110 to transfer a pulling force from the rock bolt 130 to the anchoring element 110 when the rock bolt 130 is pulled away from a bottom of the bore hole, such that the abutment element 120 forces the anchoring element 110 to rotate outwards from the rock bolt 130 to assume a second state in which the anchor element 110 engages with a wall of the bore hole so as to anchor the rock bolt 130.