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 radially extending spokes and depressions on a superabrasive table, which are designed to distribute load more efficiently and enhance stability, thereby reducing chipping and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cutting elements are inserted at a rake angle to cut efficiently, then cutting performance is improved, but the critical region near the circumferential edge is subjected to high magnitude stresses causing cracking and spalling
Solution Approach 1:
The cutting face is designed with non-uniform thickness, featuring a thicker critical region near the circumferential edge and a thinner interior region. This local variation in geometry concentrates structural strength where the highest stresses occur during drilling, allowing the cutting element to maintain rake angle for efficient cutting while preventing cracking and spalling at the vulnerable edge region
Solution Approach 2:
The cutting elements are pre-stressed during manufacturing to induce compressive stresses in the critical region before actual use. This preliminary stress application creates a residual stress field that counteracts the tensile and shear stresses generated during drilling operations, preventing crack initiation and propagation at the circumferential edge
2Strength
If the cutting face is made thicker to withstand high stresses, then strength is improved, but the rate of penetration and drilling efficiency decrease
Solution Approach 1:
Rather than uniformly thickening the entire cutting face, the invention applies increased thickness specifically to the critical region near the circumferential edge where stresses are highest. The interior region maintains a thinner profile, preserving material removal efficiency and rate of penetration while providing targeted reinforcement where it is most needed for stress resistance
3Reliability
If cutting elements are made more robust to resist cracking and spalling, then reliability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The cutting element geometry is modified with a simple radial gradient in thickness from the center to the circumferential edge, creating a dome-shaped or arched profile. This straightforward geometric variation provides enhanced stress distribution and crack resistance without introducing complex multi-component structures, difficult-to-manufacture features, or assembly complications
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.