Rotary Base Control for Soil Fallback Prevention in Drilling
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Solution Overview
Problem
In deep borehole drilling, the existing double-head drilling method often experiences unintentional opening of the rotary base during extraction, leading to soil material falling back into the borehole and defects in the bored pile, which can compromise the strength and load-bearing capacity of the pile.
Innovation Solution
The drilling device features axially adjustable auger and drill pipe positions to control the rotary base between open and closed positions, with a locking mechanism and sensor system to ensure the base remains locked during extraction, preventing soil material from falling back into the borehole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotary base is opened during drilling to allow soil material to reach the drill helix, then soil removal is enabled, but during extraction the base may unintentionally open causing soil material to fall back into the borehole
Solution Approach 1:
The rotary base is designed to be dynamically adjustable between open and closed positions. During drilling, the base is in the open position to allow soil material to reach the drill helix for removal. During extraction, the base is rotated to the closed position to prevent soil material from falling back into the borehole. This dynamic reconfiguration resolves the contradiction by adapting the base state to the specific operational phase.
Solution Approach 2:
The system performs a preliminary action by closing the rotary base before extraction begins. The control unit detects when drilling is complete and automatically rotates the base to the closed position, preparing the system in advance for extraction. This preliminary closing action prevents the harmful effect of soil material falling back into the borehole during subsequent extraction operations.
2Ease of operation
If a separate drive element like hydraulic cylinder or motor is used to open and close the rotary base, then the base can be adjusted between positions, but the device complexity increases
Solution Approach 1:
The drill pipe's axial movement serves a dual function: it both advances/withdraws the drilling tool and simultaneously controls the rotary base position. When the drill pipe is pushed axially during drilling, it rotates the base to the open position. When pulled axially during extraction, it rotates the base to the closed position. This multi-functionality eliminates the need for separate drive elements, reducing device complexity while maintaining ease of operation.
Solution Approach 2:
The control mechanism for the rotary base is merged with the drill pipe assembly. The axial movement of the drill pipe is mechanically coupled to the rotation of the rotary base through a cam mechanism or similar linkage. This merging of functions combines the drilling/withdrawal motion with the base position control, eliminating redundant components and simplifying the overall device structure.
3Reliability
If the auger and drill pipe are axially adjustable between different lifting positions, then the rotary base can be controlled to remain closed during extraction, but the device complexity increases
Solution Approach 1:
The system employs dynamic axial adjustment of the auger relative to the drill pipe during the extraction process. The auger can be axially displaced within the drill pipe to maintain proper engagement and control the rotary base position. This dynamic adjustment ensures reliable prevention of soil material fallback while using existing mechanical components rather than adding complex new systems.
Data Source
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AI summary
The invention relates to a drilling device (20) and a method for producing a borehole in the ground with a drill auger (22) which is rotatably driven and has at least one helix (24) which runs along a central inner tube (26), a drill pipe (30) which is rotatably driven independently of the drill auger and surrounds the drill auger at least partially, and a rotating base (40) which is rotatably arranged on a lower region of the drill auger and is adjustable between a drilling position in which a passage for soil material to the helix is open, and a closing position in which the passage is closed.According to the invention, it is provided that, for adjusting the rotary base, the auger and the drill pipe are axially adjustable relative to each other between a first stroke position and a second stroke position, that in the first stroke position the rotary base is arranged in the drilling position with the passage open, that in the second stroke position the rotary base is arranged in its closed position with the passage closed, and that a control is provided and designed which indicates to a device operator whether the auger is in the first or the second stroke position and/or the rotary base is in the closed position.