Reamer Assembly Gearbox and Collar for Microtunneling Spoil Control
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Solution Overview
Problem
Existing microtunneling methods face challenges in accurately directing drill heads, leading to unnecessary spoil removal and inefficiencies due to the mismatch between pilot hole diameter and reamer cutting head diameter, and the use of vacuum arrangements for spoil removal is not ideal.
Innovation Solution
A reamer assembly with a gearbox configured to increase torque by more than double, a cylindrical housing to protect and cool the gearbox, and a body for efficient spoil extraction through the borehole, along with a drill string design featuring adjustable latch connections and fluid pathways for cooling and spoil conversion to slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a drill head is used to drill a hole through the ground, then a micro tunnel can be produced, but it is difficult to accurately direct the drill head and unnecessary spoil is removed
Solution Approach 1:
The tunneling process is divided into two stages: first drilling a small diameter pilot hole with a drill head, then enlarging it with a reamer assembly. This segmentation allows the pilot hole to establish accurate direction while the reamer removes the necessary spoil to create the final tunnel diameter.
Solution Approach 2:
A pilot hole is drilled first to establish the correct path and direction before the reamer assembly is deployed to enlarge the hole. This preliminary action ensures that subsequent spoil removal is minimized by staying within the defined pilot hole trajectory.
2Volume of moving object
If a reamer assembly is used to enlarge the pilot hole, then the tunnel diameter can be increased, but the cutting head churms spoil rather than cutting into the working face because the pilot hole diameter is smaller than the reamer cutting head diameter
Solution Approach 1:
A collar is introduced as an intermediary component between the reamer cutting head and the pilot hole. The collar has an internal diameter that matches the pilot hole diameter, creating a sealed interface that allows the larger reamer cutting head to efficiently cut into the working face without churning spoil in the smaller pilot hole.
Solution Approach 2:
The system transitions from a single-diameter approach to a multi-diameter configuration where the collar provides a transition zone. The collar's internal diameter matches the pilot hole while the reamer cutting head has a larger external diameter matching the final tunnel requirement, optimizing the cutting process at each stage.
3Loss of substance
If a vacuum arrangement is used to remove spoil through the pilot hole, then spoil can be extracted, but this is not ideal because the cutting head produces spoil at a diameter greater than the pilot hole
Solution Approach 1:
The collar acts as an intermediary that creates a sealed interface between the pilot hole and the larger reamer cutting head. This seal allows spoil to be efficiently removed through the collar and drill string system, matching the spoil production rate of the reamer cutting head.
Solution Approach 2:
The system uses pressurized fluid supplied through the drill string to facilitate spoil removal. The fluid helps transport spoil through the collar and drill string, replacing the less effective vacuum arrangement with a more efficient pneumatic-hydraulic system.
4Ease of operation
If the drill string is under tension to draw the reamer assembly back through the pilot hole, then the reamer can be positioned, but torque transmission to the cutter may be insufficient
Solution Approach 1:
The system replaces direct mechanical torque transmission through the drill string with a hydraulic drive system. A hydraulic motor converts hydraulic pressure into rotational torque at the cutter, providing sufficient power independent of the drill string tension and allowing effective cutting at the larger reamer diameter.
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
Enhances torque transmission, reduces wear on gearbox components, improves spoil extraction efficiency, and facilitates smoother operation by minimizing unnecessary spoil removal and optimizing spoil handling.
Implementation Method 1
a fluid path from the cylindrical housing through the mount for fluid supplied through the drill string to cool the gearbox and travel over the cutter elements
Data Source
AI summary
This invention relates to a reamer assembly (6) for enlarging a substantially horizontal pilot hole (14) in the ground to produce a bore hole (18), including a cutter (21) which is rotatable about an axis X-X. A gear box (20) is positioned on a first side of the cutter (21) for interacting with a drive shaft (33) which is rotated about the axis X-X by a drive apparatus (2) outside the pilot bore hole (14) and a body (15) positioned on a second side of the cutter (21) for transferring thrust from a thrust apparatus (4) outside of the enlarged bore hole (18) to the cutter (21).