Earth-Boring Drill Bit Metal Face Seal Void Elimination
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Solution Overview
Problem
Existing earth-boring drill bits with metal face bearing seals suffer from a void between the rigid metal face seal, elastomeric energizer ring, and secondary seal, which requires filling with oil or lubricant, and are prone to debris entry from the exterior.
Innovation Solution
The design incorporates an elastomeric secondary seal ring with a triangular protrusion that fills the void between the rigid seal ring, elastomeric energizer ring, and secondary seal ring, and a recessed bit leg with a flat base to deform and seal effectively, eliminating the need for filler oil and enhancing debris exclusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid metal face seal with secondary seal is used, then sealing against foreign debris is improved, but a void is formed between the seal components requiring filler lubricant
Solution Approach 1:
The seal is divided into distinct functional segments: a rigid metal face seal ring for primary sealing, an elastomeric energizer ring for maintaining contact pressure, and a secondary seal ring with a protrusion for filling voids. Each segment performs a specific function, and together they create a comprehensive sealing system that eliminates the need for filler lubricant while maintaining reliability.
2Reliability
If filler lubricant is used to fill the void between seal components, then sealing is maintained, but foreign debris can still enter and damage the bit
Solution Approach 1:
The secondary seal ring is made of elastomeric material that can deform to conform to the void space between the rigid seal ring and energizer ring. This flexible seal creates a continuous barrier that blocks foreign debris while accommodating variations in assembly tolerances and wear, eliminating the need for filler lubricant that could be contaminated.
3Loss of substance
If the secondary seal ring is designed with a protrusion to fill the void, then the need for filler oil is eliminated, but stress concentration and extrusion risks increase
Solution Approach 1:
The secondary seal ring is pre-formed with a protrusion that is designed to elastically deform during installation and operation. This preliminary shaping allows the protrusion to fill the void space and engage with the cone's seal surface before any damage can occur, while the elastomeric material's inherent elasticity prevents stress concentration and extrusion under operating conditions.
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 configuration significantly reduces the volume of the void, minimizes debris entry, and extends the drill bit's life by ensuring a consistent and effective seal, with up to 95% of the void space filled by the secondary seal ring, thereby preventing foreign particles from entering the seal gland.
Implementation Method 1
An elastomeric energizer ring is squeezed between an outer diameter portion of the bearing pin and the rigid seal ring. This placement causes the energizer ring to bias the rigid seal ring forward into contact with the rearward facing seal surface.
Implementation Method 2
A rigid seal ring has a forward facing seal surface which engages the rearward facing surface of the cone in sliding engagement to form a seal as the cone rotates during drilling.
Data Source
AI summary
A metal face seal for an earth boring drill bit where the drill bit has a bit body, at least one bit leg, a bearing pin on each bit leg, and a cone rotatably mounted on each bearing pin. The metal face seal is located in the cavity formed between the interior surface of the cone and the bearing pin. The metal face seal consists of a rigid seal ring having a forward surface that engages a rotating seal surface of the cone. An energizer ring biases the rigid seal ring toward the rotating seal surface. A secondary seal engages the bearing pin surface, the energizer ring, and the rigid seal ring. The secondary seal ring has a protuberance on its forward side for filling void spaces between the energizer ring, the rigid seal ring, and the secondary seal ring.