Reverse Circulation Drill Bit Assembly With Dual Flushing Grooves
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Solution Overview
Problem
Existing reverse circulation drilling methods suffer from low recovery of drilled cuttings due to leakage of flushing medium around the hammer, reducing the percentage of samples returned to the surface.
Innovation Solution
A drill bit assembly with a central bore and dual flushing groove system, where a portion of the flushing medium is directed through smaller bore feed channels to create a suction effect, increasing the percentage of cuttings returned to the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flushing medium is delivered to the cutting face via flushing grooves, then cutting efficiency is improved, but medium leakage around the hammer increases and sample recovery decreases
Solution Approach 1:
The flushing medium delivery system is segmented into two separate groove systems: first flushing grooves deliver medium to the cutting face for efficient rock breakdown, while second flushing grooves deliver medium to the central bore for sample recovery. This segmentation allows independent optimization of each function without compromising the other.
Solution Approach 2:
The second plurality of flushing grooves acts as an intermediary pathway, directing a portion of the flushing medium from the outer surface directly into the central bore. This intermediary system creates a controlled flow path that prevents medium leakage around the hammer while maintaining adequate flushing at the cutting face.
2Temperature
If flushing medium flows around the outside of the hammer, then cooling effect is provided, but upstream flow rate in central bore decreases and sample collection efficiency is reduced
Solution Approach 1:
The patent applies local quality by providing flushing medium at two distinct locations: the cutting face for local cooling and rock breakdown, and the central bore for sample recovery. The second plurality of flushing grooves delivers medium directly to the bore region, creating localized flow that enhances sample recovery without relying on external leakage for cooling.
3Device complexity
If a single flushing groove system is used, then device complexity is reduced, but ability to create suction effect and increase sample recovery is limited
Solution Approach 1:
The flushing groove system is divided into two separate pluralities with distinct functions. The first plurality delivers medium to the cutting face, while the second plurality delivers medium to the central bore. This segmentation enables the creation of a suction effect in the bore that increases cuttings recovery percentage without significantly increasing overall system complexity.
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 suction effect enhances the recovery of drilled cuttings by reducing medium leakage and increasing the upstream flow rate in the central bore, thereby improving sample collection efficiency.
Implementation Method 1
by providing a portion of the flushing medium directly to the central bore of the bit via the second plurality of flushing grooves, a suction effect is created which increases the percentage of the sample of the drilled cuttings that is returned to the surface
Implementation Method 2
by reducing the proportion of flushing medium that is delivered to the bit face, the amount of flushing medium that leaks around the outside of the hammer is also reduced, thereby increasing upstream flow rate in the central bore of the bit
Data Source
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AI summary
The present invention relates to a drill bit assembly (1) for a reverse circulation down- the-hole hammer (100). The assembly comprises a percussion bit (2) having a head portion (3) with a cutting face (5) at a forward end thereof with engagement means (8) on the head portion for engagement with complementary engagement means (9) on a drive chuck whereby rotational drive from the drive chuck may be transmitted to the percussion bit. Connection means (11) are provided on the drive chuck adapted for connecting the drive chuck to a drive means of the down-the-hole hammer. The percussion bit comprises a central bore (13) in fluid communication with the cutting face of the bit for returning a sample of drilled cuttings to the surface, a first plurality (17) of flushing grooves in an outer surface of the head portion, configured to deliver a supply of flushing medium to the cutting face of the bit and a second plurality (18) of flushing grooves in an outer surface of the head portion, configured to deliver a supply of flushing medium to the central bore.