Lubricating Nutating Single Cone Drill Bit
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Solution Overview
Problem
Existing single cone drill bits experience excessive wear and torque due to scraping of cutter elements, leading to premature failure and the need for frequent lubrication replenishment, which limits their down-hole service life.
Innovation Solution
A lubricating nutating single cone drill bit with an axially skewed bore and multiple bearings, featuring a lubricant chamber driven by drilling fluid to dispense lubricant to bearing surfaces, and radial dynamic seals to prevent contamination, ensuring the bearings' longevity matches the cutter elements' lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single cone drill bit is used to reduce bearing size and increase compressive loading capacity, then the bearing size is reduced and compressive loading capacity is increased, but the cutter elements experience excessive scraping wear and torque
Solution Approach 1:
The drill bit employs a nutating cone mechanism where the cone axis is skewed relative to the drill string axis, creating a dynamic nutating motion that alternates between cutting and scraping phases. This dynamic motion allows the cutter elements to engage the formation in compression during the cutting phase while minimizing continuous scraping contact, thereby maintaining high compressive loading capacity while reducing excessive wear.
2Duration of action of moving object
If a nutating single cone drill bit is used to extend cutter element service life, then cutter element wear is reduced and service life is extended, but bearing lubrication duration becomes the limiting factor
Solution Approach 1:
The drill bit incorporates a lubricant reservoir pre-filled with lubricant before deployment. This preliminary action ensures that sufficient lubricant is available for the entire anticipated service life of the cutter elements, eliminating the need for intermediate lubrication replenishment and ensuring continuous bearing protection throughout the extended cutter element operational period.
Solution Approach 2:
The system includes a plunger mechanism that automatically dispenses lubricant to the bearings based on operational conditions. This self-service mechanism ensures continuous bearing lubrication without requiring external intervention or trip-out operations, allowing the bearing lubrication duration to match the cutter element service life.
3Reliability
If frequent trip-out operations are performed to replenish lubrication, then bearing lubrication is maintained, but productivity is reduced due to lost time
Solution Approach 1:
The drill bit incorporates a continuous lubrication delivery system with a plunger mechanism that automatically dispenses lubricant to the bearings during continuous drilling operations. This eliminates interruptions for lubrication replenishment, maintaining continuous useful action (drilling) while ensuring bearing lubrication is continuously maintained, thereby preserving both reliability and productivity.
4Duration of action of stationary object
If radial dynamic seals are added to prevent contamination, then bearing life is extended, but device complexity increases
Solution Approach 1:
The drill bit employs radial dynamic seals that utilize flexible sealing elements to prevent contaminant ingress to the bearings. These seals are integrated into the existing bearing housing structure, providing effective contamination protection while minimizing additional complexity through the use of flexible sealing components that adapt to the dynamic nutating motion.
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
The solution extends the service life of the drill bit by maintaining bearing health through continuous lubrication, reducing the need for frequent bit removal and replacement, and minimizing torque and wear, allowing for longer down-hole operation without compromising cutter element longevity.
Implementation Method 1
containing a plunger displaceable by a drilling fluid to dispense a lubricant to the plurality of bearings
Implementation Method 2
a radial dynamic seal restricts contaminants from contacting the bearing surfaces
Data Source
AI summary
A lubricating nutating single cone drill bit 10 is disclosed. Bit 10 includes a bit shank 12 with an axially skewed bore 18 rotatably retaining a cutter body 22. A plurality of cutter elements (46, 48) are affixed to the cutter body 22. Bearings (26, 28, 30, 32) enable rotation of the cutter body 22 and lubricant is dispensed to the bearings from a lubricant chamber (76, 76′) by a plunger 80 driven by drilling fluid. A method to drill includes attaching the bit 10 to a drill string, engaging the bit 10 into a formation (WB), pumping a drilling fluid into a plunger 80 in the lubricant chamber 76 to dispense lubricant to the bearings (26, 28, 30, 32). The method can include pumping the drilling fluid through a fluid passage 90 in the bit 10 and out of a low pressure orifice 94 on the cutter body 22.