Shape Memory Locking for Thermally Stable PDC Cutters

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Solution Overview

Problem

Polycrystalline diamond compact cutting elements used in earth boring tools face thermal degradation due to catalyst material retention, leading to internal stress and chemical breakdown, and fully leached diamond tables are brittle and difficult to secure.

Innovation Solution

Employing shape memory materials to create mechanical interference between the cutting elements and the drill bit body, allowing for secure retention without the need for brazing and minimizing thermal stress on the diamond tables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If catalyst material is retained in the diamond table, then the diamond table can be formed through HTHP sintering process, but thermal degradation and internal stress occur at high temperatures

Engineering Contradiction:

ImproveHTHP sintering processVSAvoidthermal stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent removes the catalyst material from the diamond table through acid leaching or other extraction methods after the HTHP sintering process. This extraction eliminates the source of thermal degradation and internal stress while preserving the diamond table structure formed during sintering.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies a coating to the diamond table before or during the HTHP sintering process that prevents catalyst material from remaining in the diamond table. This preliminary protective action avoids thermal degradation issues that would otherwise occur with retained catalyst material.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If catalyst material is completely leached out from the diamond table, then thermal stability is improved, but the diamond table becomes more brittle and vulnerable to stresses

Engineering Contradiction:

Improvethermal stabilityVSAvoidresistance to shear, compressive, and tensile stresses

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies a coating specifically to the diamond table that provides localized reinforcement. This coating is applied only where needed to compensate for the brittleness caused by catalyst removal, rather than uniformly treating the entire diamond table or substrate assembly.

Inventive Principle:

Principle #3Local quality

3Reliability

If catalyst material is completely leached out from the diamond table, then thermal stability is improved, but it becomes difficult to secure the diamond table to the substrate

Engineering Contradiction:

Improvethermal stabilityVSAvoidattachment to substrate

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces a coating as an intermediary layer between the diamond table and the substrate. This coating serves as a bonding agent that facilitates attachment to the substrate while the underlying diamond table remains free of catalyst material for thermal stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Strength

If brazing is used to secure cutting elements to the drill bit body, then strong attachment is achieved, but thermal stress is imposed on the diamond tables

Engineering Contradiction:

Improveattachment strengthVSAvoidthermal stress

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the thermal brazing process with a mechanical attachment system. The cutting element is secured through mechanical means such as interference fits, retention members, or clamping mechanisms that do not require high-temperature heating, thereby avoiding thermal stress on the diamond table while still achieving strong attachment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The use of shape memory materials effectively secures cutting elements, reducing thermal stress and maintaining the integrity of the diamond tables, thereby enhancing the durability and effectiveness of the cutting elements during high-temperature operations.

Implementation Method 1

A shape memory material may be used to create mechanical interference between a cutting element and a body

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Alloy

Implementation Method 2

The shape memory material may be converted to another solid phase to form the shape memory material having different dimensions

Methodology Applied

Scientific EffectPhase transition: Phase Change

Data Source

PatentEP3583289B1Mechanical locking mechanism using shape memory material

Publication Date: 2023.05.24 BAKER HUGHES CO

Figure 1
Figure 2A~3B
Figure 4A~5

AI summary

A fastening apparatus includes a retaining member comprising a shape memory material configured to transform, responsive to application of a stimulus, from a first solid phase to a second solid phase. The retaining member is disposed within a hole in a body and secured within the hole by phase change which creates an interference fit to secure the retaining member against rotational and axial movement. The hole has a second axial cross-sectional shape. The retaining member has a first axial cross-sectional shape that is preferably either circular or rectangular.