Shaped Cutter Alignment Structure for Drill Bit Back Rake Angle Control

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Solution Overview

Problem

Conventional drill bits with axially symmetrical cutters face challenges in maintaining optimal back rake angles during drilling, leading to reduced performance and increased wear when encountering varying formation hardness, as the fixed geometry does not adapt to changing cutting depths, resulting in issues like impact damage, cracking, and reduced rate of penetration.

Innovation Solution

The introduction of axially asymmetrical shaped cutters with alignment structures, such as protrusions or depressions, on the substrate to ensure precise orientation and rotation within the drill bit pockets, allowing for adjustable back rake angles and improved cutting efficiency by aligning with counter-alignment structures on the pockets, fabricated using techniques like laser cutting or EDM to enhance cutter performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If axially symmetrical cutters are used, then manufacturing is simpler and easier, but the back rake angle cannot be maintained optimally when encountering varying formation hardness

Engineering Contradiction:

Improvecutter manufacturing simplicityVSAvoidback rake angle maintenance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by transitioning from axially symmetrical cutters to axially asymmetrical shaped cutters. The shaped cutters have non-uniform geometry with specific profiles designed to maintain optimal back rake angles when encountering varying formation hardness. This asymmetrical shape allows the cutting face to adapt to different rock conditions while maintaining reliable contact angles, resolving the contradiction between manufacturing simplicity and back rake angle maintenance.

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If fixed geometry cutters are used, then device complexity is reduced, but performance decreases when cutting depth varies

Engineering Contradiction:

Improvecutter geometry complexityVSAvoidrate of penetration

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent applies local quality by designing cutters with non-uniform geometry where different portions of the cutter have specifically tailored shapes and angles. The shaped cutters feature varying profiles along their length, with each section optimized for specific cutting conditions and depths. This local differentiation allows the cutter to maintain high performance across varying cutting depths without requiring multiple different cutter types, thus improving productivity while controlling complexity.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If conventional cutters are used, then ease of operation is maintained, but wear increases and durability decreases

Engineering Contradiction:

Improvedrilling operation simplicityVSAvoidcutter durability

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent applies dynamics by designing cutters with shapes that dynamically adapt to cutting conditions. The shaped cutters have geometries that allow them to self-adjust their effective cutting angles and contact surfaces as cutting depth and formation hardness vary. This dynamic adaptation occurs through the fixed but optimized geometry that naturally maintains optimal back rake angles, reducing wear and extending cutter life without complicating the drilling operation.

Inventive Principle:

Principle #15Dynamics

4Ease of operation

If symmetrical cutter design is used, then alignment is simpler, but cutting efficiency is reduced

Engineering Contradiction:

Improvecutter alignment simplicityVSAvoidcutting efficiency

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent resolves this contradiction by implementing asymmetrical shaped cutters with built-in alignment features. The asymmetrical design includes specific geometric elements such as keyed sections or orientation markers that provide positive alignment during installation. These alignment features ensure the cutter is correctly oriented in the pocket, maintaining cutting efficiency while keeping the alignment process simple and straightforward through inherent geometric guidance.

Inventive Principle:

Principle #4Asymmetry

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

This solution enables the drill bit to maintain optimal cutting face orientation with respect to the formation, enhancing the rate of penetration and cutter durability by allowing adaptive adjustment of back rake angles, reducing wear and increasing drilling efficiency across different formations.

Implementation Method 1

each of the plurality of cutters has at least one alignment structure to align with at least one counter-alignment structure on each of the pockets to locate the rotary orientation between each of the plurality of cutters and each of the corresponding pockets

Methodology Applied

Scientific EffectMechanical alignment: Mechanical Force

Data Source

PatentUS11661799B2Shaped cutter with alignment structure for drill bit and assembly method thereof

Publication Date: 2023.05.30 CNPC USA CORP

AI summary

Disclosed is a drill bit for cutting formation comprises a bit body, a plurality of cutters, a plurality of blades with pockets to accommodate the cutters respectively. Each of the plurality of cutters has at least one alignment structure to align with at least one counter-alignment structure on each of the pockets to locate the rotary orientation between each of the plurality of cutters and each of the corresponding pockets.