Over-bit Backreamer Torque Transfer Mechanism

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Solution Overview

Problem

Existing backreamer systems require separate attachment to the drill string and removal of the rock bit for backreaming operations, which is inefficient and disrupts the drilling process.

Innovation Solution

A backreamer kit comprising a rock bit and an over-bit backreamer with a slanted steering face and internal cavity, allowing the rock bit to provide rotational and pullback force to the backreamer without separate attachment, enabling continuous operation by placing the backreamer around the rock bit and utilizing mating features for torque and force transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a separate backreamer attachment system is used, then the backreaming function is achieved, but the operational efficiency decreases and the process complexity increases

Engineering Contradiction:

Improveoperational efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent combines the rock bit and backreamer into a single integrated assembly where the backreamer is positioned over the rock bit on the drill string. The backreamer includes cutting teeth for enlarging the borehole while the rock bit continues drilling, eliminating the need for separate attachment operations and enabling continuous drilling-backreaming operations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The drill string assembly performs multiple functions simultaneously: the rock bit drills the pilot bore while the backreamer on the same drill string enlarges the borehole. This multi-functional design allows the same drill string to perform both drilling and backreaming operations without requiring separate equipment or operations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If the rock bit is removed for backreaming operations, then the backreamer can be properly attached, but the drilling process is disrupted and time is lost

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidprocess interruption time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The integrated design allows the rock bit to continue drilling while the backreamer simultaneously enlarges the borehole in reverse. Both operations occur continuously without stopping the drill string rotation or removing components, maintaining continuous useful action throughout the process.

Inventive Principle:

Principle #20Continuity of useful action

3Device complexity

If the backreamer is designed to fit over the rock bit, then separate attachment is eliminated, but the internal cavity design becomes more complex

Engineering Contradiction:

Improveattachment system complexityVSAvoidinternal cavity manufacturing complexity

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The backreamer is designed as a hollow cylindrical structure that nests over the rock bit, with the rock bit passing through the internal cavity of the backreamer. This nested configuration allows the smaller rock bit to be contained within the larger backreamer structure, eliminating the need for separate attachment mechanisms while maintaining structural integrity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS10584537B2Over-bit reamer

Publication Date: 2020.03.10 CHARLES MACHINE WORKS INC

AI summary

An over-bit backreamer. The backreamer is configured to be placed over a bit without detaching the bit from a drill string associated with a pilot bore. The backreamer has an internal surface that conforms to a steering surface of the bit. Rotation is transferred from the bit to the backreamer at the internal surface. The backreamer further defines a flange which interacts with a feature, such as a heel, on the bit. The flange and heel form a shoulder which transfers pullback force to the bit. The backreamer comprises a pullback eye that pulls a product pipe back through the borehole.