Rock Drill Anchor System for Borehole Force Distribution
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Solution Overview
Problem
Existing rock drilling machines are limited by the axial force required to displace the drill string and drill bit within the borehole, restricting the length of boreholes that can be drilled due to the weight and frictional forces involved.
Innovation Solution
A rock drilling machine with a support device on the outside of the borehole that includes an anchor system with preloadable support shoes, connected to a hydraulic or other actuator system, allowing for axial displacement and radial support of the drill string, enabling increased axial force application to the drill bit and overcoming frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the drill string weight and frictional forces are increased to achieve deeper boreholes, then the drilling depth is improved, but the axial force required to displace the drill string becomes excessive and limits further drilling progress
Solution Approach 1:
The anchor system is divided into multiple support shoes (at least two) distributed along the borehole wall, with each shoe independently adjustable and load-bearing. This segmentation allows the total axial force to be distributed across multiple contact points, reducing the force requirement at any single location while maintaining cumulative drilling capability.
Solution Approach 2:
The invention introduces a radial dimension to force application by having support shoes engage with the borehole wall radially outward. Instead of only axial force transmission through the drill string, the anchor system creates a three-dimensional force distribution with radial support components, enabling better mechanical advantage and reduced axial force requirements.
2Productivity
If the axial force is increased to overcome friction and displace the drill string, then the drilling capability is improved, but the complexity of the force transmission system increases
Solution Approach 1:
The support shoes are designed to self-adjust and self-regulate their engagement with the borehole wall through preload mechanisms. The system automatically distributes loads and maintains optimal contact pressure without requiring complex external control systems, reducing operational complexity while maintaining high drilling capability.
Solution Approach 2:
The anchor system acts as an intermediary between the drill string and the borehole wall, providing a distributed force transmission interface. This intermediary structure simplifies the overall system by replacing direct high-force axial transmission with a mediated distributed contact system, reducing the complexity of force management.
3Reliability
If the support shoes are made preloadable and axially displaceable to compensate for unintentional displacement, then the drilling stability is improved, but the device complexity increases
Solution Approach 1:
The support shoes are designed with dynamic characteristics, being axially displaceable to accommodate unintentional displacement during drilling. This dynamic capability allows the anchor system to adapt to position variations and maintain stable drilling conditions, improving reliability through controlled flexibility rather than rigid fixation.
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 anchor system enhances the ability to displace the drill string and apply sufficient axial force to the drill bit, allowing for longer borehole drilling by compensating for unintentional displacement and distributing force effectively along the borehole wall, thus overcoming the limitations of prior art drilling devices.
Implementation Method 1
The support shoe (30) is axially displaceable relative to the string portion (6) and is preloadable against the borehole wall (2) with a force in a radial direction
Implementation Method 2
a feed cylinder (48) being positioned inside a guide pipe (26) forming part of the string portion (6) and connecting the string portion (6) and the anchor (8) in an axially slidable manner
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A device for a rock drilling machine (1) for drilling of boreholes (2) in rock, where the rock drilling machine (1) comprises a drilling portion (4) and a string portion (6) which by means of joinable pipes (20) are connected to a support device on the outside of the borehole (2), and where the string portion (6) is provided with an anchor (8) comprising at least one against the borehole (2) preloadable and relative to the string portion (6) axially displaceable support shoe (30).