Hard Material Plate Attachment for Rotary Cone Drill Bit Wear
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Solution Overview
Problem
Existing rotary cone drill bits face significant wear issues at the shirttail edge and leading edge, leading to premature failure, particularly when operating in abrasive rock formations, as current methods like tungsten carbide hardfacing and press-fit inserts provide inadequate protection due to rapid wear and positioning limitations.
Innovation Solution
The implementation of hard material plates, such as polycrystalline diamond compact or solid tungsten carbide, adhered to the shirttail and leading edges within slots on the drill bit leg, using a flowable adhesive like brazing material for secure attachment, which provides enhanced abrasion resistance without the limitations of traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tungsten carbide hardfacing material is applied to the shirttail edge, then abrasion resistance is improved, but the material wears down too quickly in highly abrasive rock formations
Solution Approach 1:
The patent applies a composite material system consisting of tungsten carbide particles embedded in a cobalt matrix (WC-Co hardfacing material) rather than using pure tungsten carbide or nickel-based hardfacing. This composite structure provides both high abrasion resistance from the tungsten carbide particles and adequate toughness from the cobalt matrix, preventing premature wear while maintaining structural integrity at the shirttail edge.
2Strength
If tungsten carbide inserts are press-fit into holes near the shirttail edge, then abrasion resistance is improved, but the inserts do not provide protection for the actual shirttail edge due to positioning limitations
Solution Approach 1:
The patent applies hardfacing material specifically localized to the shirttail edge region where wear occurs most severely. The hardfacing is applied in a band approximately 1/8 to 1/4 inch wide centered on the shirttail edge, providing targeted protection exactly where needed rather than protecting areas that don't require it. This localized application ensures the shirttail edge itself is protected while avoiding the positioning limitations of press-fit inserts.
3Strength
If press-fit inserts are used to protect the shirttail region, then abrasion resistance is improved, but the inserts require significant thickness to be suitably retained
Solution Approach 1:
The patent replaces the mechanical press-fit retention system with a metallurgical bonding system. Instead of relying on mechanical interference fits that require thick inserts for retention, the hardfacing material is metallurgically bonded to the bit body through welding or diffusion bonding processes. This substitution allows for thinner protection layers while maintaining secure attachment, eliminating the need for thick inserts required by mechanical retention methods.
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 solution significantly reduces wear and erosion at the shirttail and leading edges, extending the drill bit's operational life by using denser, more abrasion-resistant materials that are securely attached without the need for peripheral retention, thus improving durability in abrasive conditions.
Implementation Method 1
A flowable adhesive material is interposed between the bottom surface of the hard material plate and the floor surface of the leg
Implementation Method 2
using denser, more abrasion-resistant materials that are securely attached without the need for peripheral retention, thus improving durability in abrasive conditions
Data Source
AI summary
A rotary cone drill bit includes: a body, a leg depending from the body, a bearing shaft extending from the leg and a cone mounted to the bearing shaft. The leg includes a surface edge that is subject to wear during operation of the bit. A bottom surface of a hard material plate having an edge is attached to a conforming surface of the leg in a position where the edge of the hard material plate defines at least a portion of the surface edge of the leg. The attachment of the surfaces is made using a flowable material such as a brazing material.