Rotating Drill Bit Cone Leg Assembly and Sealing
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Solution Overview
Problem
Conventional rotating cone drill bits face issues such as premature bearing failure, inadequate mud flow, cone wobble, and reduced durability due to design limitations, leading to decreased drilling efficiency and shortened bit life.
Innovation Solution
The method involves assembling cone-leg assemblies with thermally fitted seal risers, O-ring seals, and extended mud nozzles to enhance sealing and lubrication, along with a sequence of intermeshing cone orientations to prevent interference, and using silver talc additives in lubricants for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ball bearing retention design is used, then cone rotation is enabled, but bearing wear accelerates due to poor retention and high unit loads
Solution Approach 1:
The bearing retention system is segmented into multiple retention balls distributed around the cone circumference, each held in place by individual grooves and springs. This segmentation allows even load distribution and prevents any single bearing point from overheating or failing prematurely.
Solution Approach 2:
The patent changes the retention mechanism from a simple gravity-based system to an active spring-loaded system. The springs apply constant radial force on the retention balls, maintaining optimal contact pressure between the bearing surfaces and preventing cone wobble or gimbal motion during rotation.
2Ease of operation
If radial clearance grooves are defined in cone surface, then cutting structure clearance is provided, but cone shell is weakened and material is removed
Solution Approach 1:
Instead of removing material throughout the cone shell, the patent adds protective inserts only at the specific locations where cutting structures require clearance. These localized reinforcement inserts provide the necessary clearance space without compromising the overall structural integrity of the cone shell.
Solution Approach 2:
The patent uses composite construction by incorporating separate protective inserts (made from wear-resistant materials) into the cone shell structure. These inserts are strategically placed to provide clearance for cutting structures while the main cone shell retains its full strength from the base material.
3Adaptability or versatility
If cones rotate on journals with ball bearings, then cutting structures can be positioned, but journal bearing strength is limited by radius
Solution Approach 1:
The patent transitions from a simple radial journal bearing design to a more complex three-dimensional bearing arrangement with retention balls positioned in grooves around the cone circumference. This dimensional change allows the bearing to handle both radial and axial loads simultaneously, significantly increasing the overall strength and load-carrying capacity of the journal bearing system.
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 approach results in a drill bit with increased rate of penetration, extended lifespan, and improved durability by reducing wear, enhancing mud flow efficiency, and maintaining effective lubrication, thereby overcoming the limitations of traditional designs.
Implementation Method 1
disposing an O-ring seal within an O-ring gland defined in the base of the cone, disposing the cone over the journal, pressing the O-ring seal of the cone onto the seal riser bushing
Implementation Method 2
injecting an ambient or heated lubricant through an lubricant access bore while rotating the cone about the journal to force the lubricant from a distal axial entry port in the journal
Implementation Method 3
thermally fitting and securing a seal riser bushing to a journal of a leg
Data Source
AI summary
A method includes the steps of assembling cone-leg assemblies, rotating the cones on their respective cone-leg assemblies to predetermined orientations such that cutting structures of one of the cone-leg assemblies are clear from the cutting structures of neighboring cone-leg assemblies, and installing the cone-leg assemblies in a predetermined sequence such that the plurality of cone-leg assemblies to intermesh with each other. Another method includes the steps of thermally fitting a plurality of one piece extended mud nozzles into the bit body to form a plurality of substantially straight direct unobstructed mud laminar flow paths, inserting a plurality of guide pins in preformed locator recesses in the body, and orienting a pre-assembled cone-leg assembly to align a groove on an inner surface of the leg with one of the plurality of guide pins, while thermally fitting the cone-leg assembly into a preformed bore in the body.