Microtunneling Connector Assembly for Remote Reamer Release
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Solution Overview
Problem
The existing microtunneling methods face challenges in efficiently directing the drill head due to deviations from the preferred line, leading to unnecessary spoil removal and potential drive shaft failure, with stress issues complicating the reaming process and impacting productivity and efficiency.
Innovation Solution
A connector assembly with a catch mechanism and adjustable detents allows for remote engagement and disengagement of the drill string from the cutting head, facilitating stress management and enabling remote problem-solving of drive shaft failures or increased jacking pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drill string is used to rotate the reamer cutting head during reaming, then the reamer can enlarge the pilot hole, but the increased stress on the drive shaft can cause drive shaft failure
Solution Approach 1:
The drill string is divided into separable segments with a modular connector assembly that allows the reamer to be detached from the drill string. This segmentation enables the drive shaft to be replaced independently without retrieving the entire drill string assembly, resolving the contradiction by maintaining reaming efficiency while protecting drive shaft reliability through easy replacement capability.
Solution Approach 2:
The connector assembly includes a dynamic catch mechanism with movable detents that can transition between locked and unlocked states. This dynamic design allows the system to adapt between the reaming operation mode (locked) and the drive shaft replacement mode (unlocked), enabling efficient reaming while facilitating quick response to drive shaft failures.
2Ease of repair
If a drive shaft failure occurs and the reamer must be retracted to a remote thrust pit for disconnection, then the drive shaft can be replaced, but considerable downtime occurs impacting efficiency and profitability
Solution Approach 1:
The drill string is divided into separable segments with a modular connector assembly located near the reamer. This segmentation allows the reamer and adjacent drill string segment to be detached at the working face without retrieving the entire assembly to a remote pit, enabling rapid drive shaft replacement and minimizing downtime while maintaining ease of repair.
Solution Approach 2:
The connector assembly is pre-configured with a catch mechanism and detents that enable quick release functionality. This preliminary preparation allows the drive shaft to be replaced rapidly when failure occurs, as the mechanism is already in place to facilitate immediate disengagement without requiring complex retrieval procedures.
3Manufacturing precision
If the drill head is directed accurately to drill a pilot hole, then unnecessary spoil removal is minimized, but deviations can still occur requiring reaming to correct the path
Solution Approach 1:
The reamer acts as an intermediary between the pilot hole and the final tunnel bore. It corrects deviations in the pilot hole by cutting a new, more accurate path while removing only the necessary amount of spoil to achieve the correct alignment, thus minimizing unnecessary spoil removal while improving manufacturing precision.
Data Source
AI summary
This invention relates to a connector assembly (21) for use with a microtunneling apparatus (1) including a drill string (13) and a cutting head (6). The drill string (13) including a drive shaft (23) which is rotatable from a proximal end of the drill string (13) by drive apparatus (2) located in a drive pit (3). The connector assembly (21) includes a catch mechanism (42) that is adjustable between a lock condition and a release condition from the proximal end of the drill string (13).