Shaped Cutting Elements for Rotary Drill Bits
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Solution Overview
Problem
Rotary drill bits face issues with cutting element failure due to cracking, spalling, and delamination caused by high stresses and residual thermal stresses, leading to reduced operating life and instability during drilling.
Innovation Solution
The use of cutting elements with shaped cutting surfaces, featuring a cylindrical substrate and a superabrasive table with radially extending spokes and depressions, which distribute load more efficiently and enhance stability, allowing for improved penetration rates and extended drilling depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cutting elements use superhard cutting faces, then cutting efficiency is improved, but the cutting surface is susceptible to cracking, spalling, and delamination under high stress
Solution Approach 1:
The cutting face is segmented into multiple raised radial spokes that extend from the center to the outer periphery. These spokes divide the cutting face into separate segments, allowing each spoke to independently withstand applied loads and preventing crack propagation across the entire cutting face. The spaces between spokes enable stress isolation and prevent delamination.
Solution Approach 2:
The spoke structure creates local variations in the cutting face geometry, with raised spokes providing localized strength and support where needed. Each spoke can be optimized for specific loading conditions, and the non-uniform distribution of material provides both cutting efficiency and stress resistance in different regions of the cutting element.
2Force
If cutting elements are subjected to high magnitude stresses, then cutting performance is improved, but cracks initiate and grow across the cutting face
Solution Approach 1:
The cutting face is divided into multiple raised radial spokes that independently bear applied loads. This segmentation prevents stress concentration from propagating across the entire cutting face, as each spoke acts as an independent load-bearing element. Cracks are contained within individual spokes or spaces between them rather than spreading across the full cutting surface.
Solution Approach 2:
The spoke structure provides preemptive stress distribution and load sharing before cracks can initiate. The raised spokes create a reinforced geometry that anticipates and distributes high magnitude stresses before they can concentrate at vulnerable points, thereby preventing crack initiation under extreme loading conditions.
3Ease of manufacture
If cutting elements have a planar cutting surface, then manufacturing is simplified, but the critical region near the circumferential edge is highly susceptible to failure
Solution Approach 1:
The cutting face is segmented into raised radial spokes with spaces between them, creating a non-planar geometry that reinforces the critical circumferential edge region. This segmentation provides structural support exactly where failure is most likely to occur, while still maintaining manufacturing feasibility through conventional forming processes.
Solution Approach 2:
The cutting face transitions from a two-dimensional planar surface to a three-dimensional structure with raised spokes and spaces. This dimensional change adds vertical relief and structural depth to the critical edge regions, providing enhanced strength and failure resistance without significantly complicating the manufacturing process.
Data Source
AI summary
Embodiments of the present invention provides cutting elements for use on rotary drill bits for drilling subterranean formations. More specifically, the present disclosure relates to cutting elements having a shaped upper surface including at least one spoke for cutting and/or failing subterranean formations during drilling. The present disclosure also relates to drill bits incorporating one or more of such cutting elements.