Drilling Device Pilot Bit Flushing Medium Redirection
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Solution Overview
Problem
Existing drilling devices often cause uncontrolled loosening and removal of soil from outside the hole when drilling in soft soil, as the pressurized flushing medium directly hits the drilled surface, leading to excessive enlargement of the hole diameter, which is undesirable in pile and horizontal drilling.
Innovation Solution
The drilling device employs a pilot bit with a channel system that redirects the flushing medium to flow horizontally inside the bit, using cutting edges to loosen soil, which is then collected in grooves and channels, preventing the flushing medium from directly hitting the drilled surface and minimizing soil loosening outside the hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressurized flushing medium flows directly towards the drilled surface, then drilling waste can be removed efficiently, but soil is uncontrolled loosened from outside the hole causing excessive hole diameter enlargement
Solution Approach 1:
The patent changes the flow direction of the flushing medium from a vertical/direct path toward the drilled surface to a horizontal path along the inner wall of the hole. The flushing medium is redirected to flow horizontally in the annular space between the drill bit and the hole wall, then returns vertically through the drill bit center. This dimensional change in flow path prevents direct impact on the drilled surface while maintaining waste removal capability.
Solution Approach 2:
The flushing medium flow path is segmented into distinct sections: a horizontal flow section along the hole wall for waste collection, and a vertical return section through the bit center. This segmentation allows the flushing medium to perform different functions in different zones - collecting waste horizontally without loosening soil, and returning vertically through the controlled path of the drill bit.
2Productivity
If cutting edges are added to loosen soil at the drilled surface, then drilling efficiency improves, but uncontrolled soil loosening occurs leading to hole enlargement
Solution Approach 1:
The patent applies cutting edges only in specific localized areas - on the horizontal flow path sections where the flushing medium flows along the hole wall. The cutting edges are positioned to cut soil that is already loosened or being transported by the horizontal flow, rather than cutting into undisturbed soil at the drilled surface. This localized application of cutting edges provides drilling efficiency without causing uncontrolled soil loosening and hole enlargement.
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 approach effectively reduces soil loosening and prevents uncontrolled enlargement of the hole diameter, allowing for efficient removal of drilling waste while maintaining the desired hole size, as the flushing medium primarily hits the inner surface of the ring bit and flows back into the casing tube.
Implementation Method 1
pressurized flushing flow does not hit the drilled surface but flows in horizontal direction towards the inner surface of the ring bit, wherein its effect upon the drilled surface is essentially weakened
Implementation Method 2
pilot bit is designed to function by means of rotation motion and edges locating in the drilling surface and directed towards the rotation direction as a cutting edge which cuts the drilled surface during earth boring
Implementation Method 3
pressurized flushing flow does not hit the drilled surface but flows in horizontal direction towards the inner surface of the ring bit
Data Source
Figure 1~2
Figure 3~4
AI summary
Drilling device which comprises a pilot bit (1) drilling a middle portion of a hole, to said bit (1) detachable fastened ring bit (2) said bit drilling outer circle of the hole, as well as an arrangement for pulling a casing tube (4) into said hole during drilling, wherein in the drilling situation both the pilot bit (1) and the ring bit (2) are fitted to be rotated and the casing tube (4) fitted to be unrotatable, and for removing drilling waste from drilled surface locating at front side of said bits (1);(2), the drilling device comprises a flushing system, by means of which flushing medium is lead via the pilot bit (1) to the drilling surface and returned therefrom into a flow space (7) locating inside the casing tube (4). The flushing medium flow has been by means of a channel system (8, 6) turned inside the pilot bit (1) to a flow which is flowing in side direction, arranged to run a portion (a) inside the pilot bit (1) in the said side direction before the flow will run in the groove (5, 6) on the surface of the pilot bit (1), which groove is open towards the drilled surface.