Segmented Chuck and Reverse Exhaust DHD Hammer
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Solution Overview
Problem
Conventional down-the-hole drill (DHD) hammers face issues with high velocity air flows and backpressure, leading to rapid wear of external parts and reduced performance, as well as the ingress of water and debris affecting internal components, and they suffer from localized burning and fatigue failure due to small torque transmission diameters in the chuck assembly.
Innovation Solution
A DHD hammer design featuring a solid core piston with a seal, a backhead with an exhaust port and check valve assembly to manage air flow, and a segmented chuck assembly with flanges to engage the drill bit shank, reducing backpressure and preventing debris ingress, while enhancing torque transmission and reducing stress on components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a central exhaust gallery is used to combine and deliver all exhausting air through the drill bit, then the exhaust function is achieved, but high velocity air flows create rapid wear of external parts and backpressure reduces tool performance
Solution Approach 1:
The exhaust system is divided into multiple separate exhaust galleries instead of a single central gallery. Each gallery handles exhaust from specific chambers (drive chamber and return chamber separately), allowing controlled air flow paths that reduce overall velocity and backpressure while maintaining effective exhaust function.
2Object-generated harmful factors
If a piston with a thru-hole is used to allow working air volumes to exhaust through the piston, then exhaust flow is enabled, but fluids can enter the drive chamber when not in use, affecting operation and performance
Solution Approach 1:
The thru-hole in the piston is removed or closed off. Instead, exhaust flow is achieved through separate exhaust galleries and valves that are opened only during active operation, preventing fluid ingress when the hammer is not in use while maintaining exhaust capability when needed.
Solution Approach 2:
Valves are positioned to close off exhaust paths before fluids can enter the drive chamber. The check valves are pre-configured to block the thru-hole and exhaust galleries when not in use, creating a protective barrier against fluid ingress before contamination can occur.
3Ease of operation
If an integrally formed chuck is used to engage shank splines, then rotational movement is provided, but small torque transmission diameter creates localized burning and fatigue failure
Solution Approach 1:
The chuck assembly is divided into multiple segmented parts instead of a single integral piece. This segmentation allows for a larger torque transmission diameter by distributing the load across multiple segments, reducing localized stresses and preventing burning and fatigue failure while maintaining rotational movement capability.
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 design effectively reduces wear and improves performance by managing air flow and preventing debris entry, while minimizing stress and fatigue in the chuck assembly, resulting in extended tool life and improved operational efficiency.
Implementation Method 1
a check valve assembly configured to seal the exhaust valve stem when in a closed configuration
Implementation Method 2
The piston generally has two end surfaces that are exposed to working air volumes i.e., a return volume and a drive volume that are filled and exhausted with each cycle of the piston
Data Source
AI summary
A down-the-hole drill hammer is provided that includes a housing, a solid core piston mounted within the housing, a seal located between the solid core piston and the housing, and a backhead configured to exhaust working fluid volumes about a proximal end of the DHD hammer. The backhead includes a check valve assembly having a plug seal that can be moved to a closed seal position by gravity. A DHD hammer having a segmented chuck assembly is also provided. The segmented chuck assembly includes a plurality of chuck segments forming a cylindrical chuck assembly.