Rotationally Indexable Drill Bit Cutters With Key Elements

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Solution Overview

Problem

Conventional rotary drill bits experience reduced life and increased wear due to high rotational speeds, necessitating frequent repair and replacement of PDC cutters, which is time-consuming and costly, especially when wear occurs in high-stress areas like the nose and shoulder regions.

Innovation Solution

The implementation of rotationally indexable cutting elements with key elements for cooperative engagement in cutter pockets, allowing for mechanical installation, removal, and replacement, enabling in-field maintenance and extended utilization without the need for specialized facilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If rotational speed of the drill bit is increased, then the rate of penetration into the subterranean earth is increased, but the life of the drill bit is decreased due to increased wear and damage of cutting elements

Engineering Contradiction:

Improverate of penetrationVSAvoidlife of the drill bit

Core Design Contradiction:

SpeedVSDuration of action of stationary object

Solution Approach 1:

The drill bit is divided into multiple interchangeable cutting elements (PDC cutters) that can be independently replaced. Each cutting element is a separate component mounted in a cutter pocket, allowing individual replacement without replacing the entire bit assembly. This segmentation enables continuous operation by replacing only the worn cutting elements while maintaining the rest of the bit structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Worn cutting elements are removed from the drill bit and replaced with fresh ones. The removed worn cutters are discarded or sent for reconditioning, while the bit body is recovered and returned to service. This allows the expensive bit body to be recovered and reused multiple times with different cutting elements, extending the overall duration of action of the drill bit system.

Inventive Principle:

Principle #34Discarding and recovering

2Ease of repair

If conventional brazing process is used to replace PDC cutters, then the cutting elements can be replaced, but the process requires controlled application of heat and specialized facilities, increasing time and cost

Engineering Contradiction:

Improvereplacement of cutting elementsVSAvoidtime for repair and replacement

Core Design Contradiction:

Ease of repairVSLoss of time

Solution Approach 1:

The thermal brazing process is replaced with a mechanical interference fit system. Cutting elements are retained in cutter pockets through a mechanical interface involving a retainer ring and interference fit between the cutting element body and the pocket. This mechanical system eliminates the need for heat application and specialized brazing facilities, allowing replacement to be performed with basic hand tools in the field.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The drill bit operator can perform cutting element replacement independently in the field without requiring specialized repair facilities. The mechanical retention system allows the operator to remove and replace cutters using simple hand tools, making the repair process self-serviceable and eliminating dependency on external repair shops.

Inventive Principle:

Principle #25Self-service

3Strength

If PDC cutters are brazed into pockets within the bit body, then the cutting elements are securely mounted, but the manufacturing process is complex and requires controlled heat application

Engineering Contradiction:

Improvemounting strength of cutting elementsVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The thermal brazing process is replaced with a mechanical interference fit system. The cutting elements are retained in cutter pockets through a mechanical interface involving a retainer ring and interference fit between the cutting element body and the pocket. This mechanical system eliminates the need for heat application and specialized brazing facilities, allowing replacement to be performed with basic hand tools in the field.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8011456B2Rotationally indexable cutting elements and drill bits therefor

Publication Date: 2011.09.06 BAKER HUGHES CO

AI summary

A cutting element for use with a drill bit includes a substrate having a longitudinal axis, a lateral surface substantially symmetric about the longitudinal axis and one or more key elements coupled to the lateral surface. The lateral surface lies between an insertion end and a cutting end of the substrate. The one or more key elements are substantially axially aligned with the longitudinal axis and configured to selectively rotationally locate the substrate in a pocket. A drill bit configured for retaining a cutting element having one or more key elements is also disclosed.