Passive Impeller Rotary Drilling Rig for Open Caissons
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Solution Overview
Problem
Existing hydraulic drilling rigs for bridge caisson construction face inefficiencies due to poor mixing of silt and water, low mud absorption, and frequent blockages in mud suction pipes, leading to reduced drilling efficiency and drill bit breakage when dealing with soft soils like silt and silty clay.
Innovation Solution
A multi-impeller passive-rotating-stirring-type rotary drilling rig is designed with a rotation bracket and four impeller shafts that rotate opposite to the drill bit, enhancing the stirring effect by relative rotation between passive impellers and cutting edges, improving mud formation and discharge efficiency without additional power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional hydraulic drilling rig is used, then the drilling operation can be performed, but the mixing effect of silt and water is poor, resulting in low mud absorption efficiency and frequent blockages
Solution Approach 1:
The passive impeller utilizes the kinetic energy from the rotating drill bit to rotate in the opposite direction, creating a self-powered mixing system. The impeller is driven by the water flow and rotational motion already present in the drilling system, converting the drill bit's rotation into counter-rotation of the impeller blades to enhance mixing without requiring additional power input
Solution Approach 2:
The system transitions from a static mixing approach to a dynamic one where the impeller rotates in opposition to the drill bit. This dynamic counter-rotation creates enhanced shear forces and turbulent mixing between silt and water, improving mud formation and discharge efficiency while preventing blockages
2Productivity
If the drill bit rotates to cut soil, then drilling progresses, but the silt and water are not fully mixed, leading to poor mud formation
Solution Approach 1:
The passive impeller creates a dynamic counter-rotation system that enhances mixing during the drilling process. As the drill bit rotates forward to cut soil, the impeller rotates in the opposite direction, creating intense shear mixing that fully combines silt and water into high-quality mud, ensuring proper mud formation without compromising drilling speed
3Device complexity
If no additional mixing device is added, then the device complexity remains low, but the stirring effect on silt is insufficient
Solution Approach 1:
The passive impeller design allows the mixing function to serve itself by utilizing the existing rotational energy from the drill bit. The impeller is passively driven by the water flow and rotational motion in the borehole, converting available kinetic energy into mixing action without requiring an independent power source or complex drive mechanism
Solution Approach 2:
The passive impeller serves multiple functions: it acts as a mixing element to combine silt and water, a discharge accelerator to improve mud flow through the drill pipe, and a flow regulator to prevent blockages. This multi-functionality is achieved within the existing drilling rig structure without adding separate systems
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
This solution significantly enhances the mixing and discharge of silt and water, improving drilling efficiency, reducing blockages, and ensuring safer operations by accelerating mud formation and discharge during the drilling process.
Implementation Method 1
the passive impellers are in contact with a hole wall of a borehole, and under double effects of the rotation of the rotation bracket and the static hole wall, the passive impellers rotate around respective impeller shafts thereof
Implementation Method 2
the mud is discharged through a mud suction port and the negative pressure in the hollow drill pipe
Data Source
AI summary
A multi-impeller passive-rotating-stirring-type rotary drilling rig for open caissons includes a hollow main drill pipe, a drill bit, four cutting edges, four impeller shafts, four passive impellers and a rotation bracket. Through being uniformly distributed at a peripheral of the drilling rig, four passive impellers contact with a hole wall of a borehole during the drilling process for passively generating relative rotation opposite to the rotation direction of the drill bit, so as to accelerate sufficient mixing of silt and water for forming mud during the drilling process.