Hammer Reamer Fixed Impact Surface Pneumatic Piston
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Solution Overview
Problem
Current horizontal directional drilling (HDD) reamers are unable to utilize a percussive cycle when retracting the drill string, limiting the efficiency of the back reaming process due to the 'open blow' alignment of internal air passages and the inability to deliver vibratory force to the cutting wheels.
Innovation Solution
A hammer reamer is designed with a fixed internal impact surface aligned to the piston stroke range, incorporating a pneumatic hammer piston to deliver percussive blows and enhance the reaming process by maintaining vibratory force during the retraction of the drill string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional reamer is pulled back through a pilot bore during drill string retraction, then the reaming operation can be performed, but the hammer component cannot deliver percussive blows due to open blow alignment of internal air passages
Solution Approach 1:
The patent inverts the conventional reamer design by incorporating a hammer component that actively delivers percussive blows during retraction, rather than passively accepting the open blow condition. The internal air passages are configured to direct pressurized air to drive a piston that strikes an impact surface, converting the retraction motion into productive percussive action that enhances reaming efficiency.
2Productivity
If the drill string is retracted with a conventional reamer, then the reaming process proceeds, but no vibratory force is delivered to the cutting wheels
Solution Approach 1:
The patent incorporates a hammer component with a piston and impact surface that generates mechanical vibrations during the retraction phase. Pressurized air drives the piston to strike the impact surface, creating vibratory forces that are transmitted to the cutting wheels, enhancing their cutting efficiency and reducing the risk of wheel binding or overheating.
3Productivity
If a hammer component is added to enable percussive action during retraction, then reaming efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the hammer component with the reamer body into an integrated assembly. The piston, impact surface, and air passage system are combined with the cutting wheel mounting structure, creating a unified device that performs both reaming and percussive functions without requiring separate components or complex linkages.
Solution Approach 2:
The reamer design achieves multi-functionality by enabling the same device to perform both cutting/reaming operations and percussive actions during the retraction phase. The hammer component shares the drill string connection and air supply system with the cutting wheels, allowing a single device to execute multiple functions that would traditionally require separate tools.
Data Source
AI summary
Disclosed is a hammer reamer comprising cutting wheels, a product-pulling feature, and a hammer component operable to deliver a percussive cycle of an internal piston component. Notably, an internal impact surface within the head of the hammer reamer is positioned relative to the piston component in the hammer consistent with a “sweet spot” position of a drill bit used in a pilot boring configuration. Unlike a slidably engaged drill bit, however, the internal impact surface in the hammer reamer is fixed in place so that the impact surface remains in the “sweet spot” of the piston stroke range. In this way, even though the hammer reamer is being pulled back through a bore while the drill string is being retracted, the hammer component may continue to deliver percussive blows to the hammer reamer head to introduce a vibratory force that contributes to the efficiency of the reaming process.