Down-the-hole Drilling Auxiliary Flush Assembly
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Solution Overview
Problem
In down-the-hole drilling, particularly in pile drilling, the careless use of flushing air leads to overdrilling and reduced weight-carrying capacity of piles due to air infiltration into cohesive soils, causing structural damage and inefficiencies in soil removal, which existing technologies struggle to mitigate effectively.
Innovation Solution
The method enhances the flushing flow arrangement by using separate axially directed feed and return flow channels and an auxiliary flush assembly to introduce fresh flushing medium at a sharp angle to the return flow openings, preventing blockages and ensuring efficient return flow of flushing medium with drilling waste, thereby controlling air circulation and preventing soil infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressurized air is used as flushing medium in down-the-hole drilling, then drilling efficiency and productivity are improved, but overdrilling and structural damage occur due to air infiltration into cohesive soils
Solution Approach 1:
The flushing flow arrangement is segmented into separate feed flow channels and return flow channels, with the return flow channels positioned at specific locations on the drilling head. This segmentation allows controlled circulation of flushing medium, enabling efficient soil removal while preventing uncontrolled air infiltration into the soil, thus resolving the contradiction between drilling efficiency and harmful air infiltration.
Solution Approach 2:
A flushing medium circulation system acts as an intermediary between the pressurized air source and the drilling site. The system includes controlled flow channels and guide surfaces that mediate the air flow, directing it to perform flushing function while preventing direct infiltration into cohesive soils, thereby maintaining productivity while eliminating harmful effects.
2Productivity
If flushing air is used to remove drilling waste, then waste removal efficiency is improved, but blockages occur in return flow channels reducing system reliability
Solution Approach 1:
The return flow channels are pre-positioned at specific locations on the drilling head, and guide surfaces are pre-configured to direct flushing medium flow. This preliminary arrangement ensures that the flushing medium follows controlled paths to reach return flow openings, preventing blockages before they occur and maintaining reliable waste removal throughout the drilling operation.
Solution Approach 2:
The flushing flow arrangement creates a feedback circulation system where flushed soil and air are continuously returned through designated channels to the surface. This feedback mechanism ensures efficient waste removal while the structured channel design prevents blockages, maintaining both productivity and system reliability.
3Reliability
If separate feed and return flow channels are implemented, then control over flushing medium circulation is improved, but device complexity increases
Solution Approach 1:
The feed flow channels and return flow channels are integrated into a unified flushing flow arrangement that circulates flushing medium through a continuous path. The guide surfaces and channel geometry merge the functions of feeding and returning flow into a coordinated system, achieving reliable circulation control while minimizing the increase in device complexity through unified design.
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 ensures safe and efficient use of pressurized air as a flushing medium, preventing overdrilling and structural damage, while maintaining the efficiency and reliability of down-the-hole drilling, thereby improving safety and reducing operational costs.
Implementation Method 1
introducing flushing medium directly from the first flushing means (6a) by means of an auxiliary flush assembly (6c) at a return flow opening assembly (6b'o) of the return flow channel/channels (6b') essentially on the drilling surface P in order to make more efficient return flow of flushing medium together with drilling waste through the one or more return flow channels (6b')
Data Source
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AI summary
The invention relates to a method for down-the-hole drilling, the drilling being carried out by an apparatus, having a drilling device (1) that comprises a casing part (2) and a drilling unit (3), at a drilling head of which there are at least first drilling means (4) and second drilling means (5), removably coupled with each other, and a flushing flow arrangement (6), and whereby the flushing medium is being brought by first flushing means (6a) of the flushing flow arrangement (6) onto the drilling surface (P) and returned from the drilling surface (P) together with the drilling waste by second flushing means (6b) of the flushing flow arrangement (6) through axially directed (s) and in respect with each other separate feed flow and return flow channels (6a', 6b') between the first and second drilling means (4,5). Return flow of flushing medium together with drilling waste through one or more return flow channels (6b') is made more efficient by introducing flushing medium directly from the first flushing means (6a) by means of an auxiliary flush assembly (6c) at a return flow opening assembly (6b'o) of the return flow channel/channels (6b') essentially on the drilling surface (P). The invention also relates to an apparatus applying the method.