PCD Cutting Element With Segmented Projections and Inclined Flange
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Solution Overview
Problem
The working life of super hard tool inserts in drill bits is limited by fracture, chipping, and cracking due to thermal expansion mismatch between the substrate and the polycrystalline diamond (PCD) layer, leading to early failure and reduced operating life.
Innovation Solution
A super hard construction with a substrate and PCD layer featuring inclined peripheral flanges and spaced projections on the interface surface, designed to distribute stress and prevent crack propagation, along with a configuration that disrupts elastic wave formation and deflects cracks, enhancing the cutting element's resistance to cracking and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polycrystalline diamond layer is bonded to a cemented tungsten carbide substrate, then the cutting element achieves high hardness and cutting capability, but thermal expansion mismatch causes cracks and reduces operating life
Solution Approach 1:
The interface surface is segmented into multiple discrete projections instead of a continuous flat surface. These projections are spaced apart to create distinct bonding zones, allowing differential thermal expansion to occur in the gaps between projections rather than generating continuous stress cracks across the entire interface.
Solution Approach 2:
The interface structure transitions from uniform flat surface to non-uniform projections with varying heights and spacing. This local variation creates zones of different stress concentration, allowing stress to be distributed and managed locally rather than uniformly across the interface, reducing crack propagation risk.
2Strength
If the substrate and super hard material layer are bonded through sintering, then strong bonding is achieved, but residual stresses from thermal expansion differences cause cracking during use
Solution Approach 1:
The projections are designed with specific spacing and height profiles before bonding occurs. This pre-designed geometry creates built-in stress relief zones that cushion against thermal expansion stresses during subsequent heating and cooling cycles, preventing crack formation before they can occur.
Solution Approach 2:
The projections feature curved surfaces rather than sharp edges, with rounded tops and smooth transitions. This curvature distributes stress more evenly across the projection surfaces and avoids stress concentration at sharp corners, reducing the likelihood of crack initiation.
3Ease of manufacture
If a flat interface surface is used between substrate and super hard material, then manufacturing is simplified, but stress concentration occurs leading to early failure
Solution Approach 1:
The interface is divided into multiple discrete projection elements rather than a continuous flat surface. This segmentation can be achieved through relatively simple processes such as selective removal of material or deposition on patterned substrates, maintaining manufacturing feasibility while dramatically improving stress distribution and reliability.
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 solution significantly extends the operating life of cutting elements by reducing the likelihood of cracking, chipping, and fracturing, and maintaining the volume and area of the super hard material exposed during use, thereby improving durability and resistance to wear and stress.
Implementation Method 1
PCD material typically comprises at least about 80 volume % of diamond and is conventionally made by subjecting an aggregated mass of diamond grains to an ultra-high pressure of greater than about 5 GPa, and temperature of at least about 1,200° C.
Implementation Method 2
subjecting an aggregated mass of diamond grains to an ultra-high pressure of greater than about 5 GPa
Implementation Method 3
temperature of at least about 1,200° C.
Implementation Method 4
A solvent-catalyst for diamond is understood be a material that is capable of promoting the growth of diamond or the direct diamond-to-diamond inter-growth between diamond grains at a pressure and temperature condition at which diamond is thermodynamically stable
Implementation Method 5
catalysing its re-precipitation
Implementation Method 6
Cobalt has a significantly different coefficient of thermal expansion from that of diamond and, as such, upon heating of the polycrystalline diamond material during use, the cobalt in the substrate to which the PCD material is attached expands and may cause cracks to form in the PCD material
Implementation Method 7
diamond particles or grains or CBN grains are placed adjacent the cemented tungsten carbide body in a refractory metal enclosure such as a niobium enclosure and are subjected to high pressure and high temperature so that inter-grain bonding between the diamond grains or CBN grains occurs
Implementation Method 8
subjected to high pressure and high temperature so that inter-grain bonding between the diamond grains or CBN grains occurs
Data Source
AI summary
A super hard construction comprises a substrate comprising a peripheral surface, an interface surface and a longitudinal axis extending in a plane and a super hard material layer formed over the substrate and having an exposed outer surface, a peripheral surface extending therefrom and an interface surface. One of the interface surface of the substrate or the interface surface of the super hard material layer comprises one or more projections arranged to project from the interface surface, the one or more projections being spaced from the peripheral surface of the substrate and a peripheral flange extending between the peripheral side edge and the interface surface. The peripheral flange is inclined at an angle of between around 5 degrees to around 30 degrees to a plane substantially perpendicular to the plane through which the longitudinal axis extends.