Pointed Diamond Cutting Elements for Drill Bit Wear Reduction
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Solution Overview
Problem
Drill bits with superhard material layers bonded to carbide substrates face stress-related issues such as delamination and fracture due to intense forces and temperature differentials during drilling, reducing their efficacy and wear life.
Innovation Solution
The use of cutting elements with a carbide substrate bonded to a diamond working end featuring a pointed geometry and a positive rake angle between 25 and 85 degrees, which helps in producing larger chips and minimizing wear by optimizing the cutting geometry and interaction with the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If superhard material layers are bonded to carbide substrates using HPHT press apparatus, then cutting element hardness and abrasion resistance are improved, but stress-related delamination and fracture occur during drilling operations
Solution Approach 1:
The patent applies parameter changes by modifying the bonding interface geometry from planar to non-planar (convex or concave). This geometric parameter change alters the stress distribution at the interface, preventing stress concentration that leads to delamination and fracture during drilling operations.
Solution Approach 2:
The invention introduces asymmetry through the non-planar interface design where the bonding surface between the superhard material layer and carbide substrate features convex or concave regions. This asymmetric geometry creates a mechanical interlock that enhances bonding stability and prevents delamination under operational stresses.
2Ease of manufacture
If conventional cutting geometry is used, then manufacturing simplicity is maintained, but cutting element wear life is reduced due to intense forces and torques
Solution Approach 1:
The patent introduces a positive rake angle parameter (25-85 degrees) for the diamond working end, which is a significant deviation from conventional cutting geometries. This parameter change optimizes chip formation and reduces cutting forces, thereby extending wear life while remaining compatible with existing HPHT manufacturing processes.
Solution Approach 2:
The invention employs a pointed geometry with curved surfaces for the diamond working end, replacing conventional flat or angular cutting edges. This curvature optimizes stress distribution and chip evacuation, reducing wear and extending the operational life of the cutting element.
3Productivity
If standard cutting geometry produces smaller cuttings, then material removal is efficient, but energy consumption for transporting cuttings increases
Solution Approach 1:
The patent modifies the cutting geometry parameters including the positive rake angle and pointed configuration to optimize chip size and shape. These parameter changes enable the production of larger, more cohesive cuttings that are easier to transport, reducing the energy required for cuttings removal while maintaining high material removal rates.
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 configuration results in 40 to 60 percent of cuttings having a volume of 0.5 to 10 cubic centimeters, reducing wear on the drill string and improving drilling efficiency by producing larger chips that require less energy to transport, thus extending the life of the cutting elements.
Implementation Method 1
The substrates and adjacent diamond crystal layers are then compressed under HPHT conditions which promotes a sintering of the diamond grains to form the polycrystalline diamond structure. As a result, the diamond grains become mutually bonded to form a diamond layer over the substrate interface.
Implementation Method 2
drag bits for example may exhibit stresses aggravated by drilling anomalies during well boring operations such as bit whirl or bounce often resulting in spalling, delamination or fracture of the superhard abrasive layer or the substrate
Data Source
AI summary
In one aspect of the present invention, a drill string has a drill bit with a body intermediate a shank and a working face. The working face has a plurality of blades converging at a center of the working surface and diverging towards a gauge of the working face. At least one blade has a cutting element with a carbide substrate bonded to a diamond working end with a pointed geometry. The diamond working end also has a central axis which intersects an apex of the pointed geometry. The axis is oriented between a 25 and 85 degree positive rake angle.