Spherical Ball Skate for Well String Injectors

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Solution Overview

Problem

Conventional well string injectors using cylindrical rollers for gripping dies face high friction issues, which can lead to inefficiencies in gripping and moving coiled tubing or continuous rod in wellbores, limiting the effectiveness of the injection process.

Innovation Solution

The use of spherical balls instead of cylindrical rollers on skates that force gripper dies together, reducing friction and enhancing the gripping mechanism by allowing the gripper dies to ride over the spherical balls as they move along the closed-loop paths of the conveyor chains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If cylindrical rollers are used on skates to force gripper dies together, then the gripping mechanism can apply force to the continuous string, but high friction occurs between the rollers and gripper dies

Engineering Contradiction:

Improvegripping forceVSAvoidfriction

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The patent replaces cylindrical rollers with spherical balls on the skates. The spherical shape allows the gripper dies to roll over the balls with significantly reduced friction compared to cylindrical contact. The sphere-to-plane contact geometry minimizes the frictional resistance during the gripping operation, directly addressing the high friction problem while maintaining the force application function.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention substitutes the cylindrical roller mechanical system with a spherical ball mechanical system. This substitution changes the fundamental contact mechanics from cylindrical-to-plane rolling to spherical-to-plane rolling, which reduces the friction coefficient and improves the efficiency of the gripping mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If cylindrical rollers are used on skates, then the gripper dies can be forced together, but the friction causes inefficiencies in gripping and moving the continuous string

Engineering Contradiction:

Improvegripping efficiencyVSAvoidfriction

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

By using spherical balls instead of cylindrical rollers, the patent creates a low-friction interface that allows gripper dies to move smoothly during the gripping operation. The spherical geometry reduces contact resistance, making the gripping process more efficient and easier to operate while consuming less energy.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Loss of energy

If spherical balls are used instead of cylindrical rollers, then friction is reduced and gripping efficiency is improved, but the balls must be contained within the skate structure

Engineering Contradiction:

ImprovefrictionVSAvoidskate structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The skate structure incorporates a curved, cup-shaped housing that naturally contains the spherical balls through its geometry. The curved walls of the housing guide and retain the balls, preventing them from escaping while allowing free movement for the rolling function. This elegant geometric solution contains the balls without requiring complex mechanical retention mechanisms.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 friction and improves the gripping efficiency of coiled tubing or continuous rod, allowing for smoother and more effective injection or withdrawal operations in wellbores by utilizing the low-friction rolling interface provided by the spherical balls.

Implementation Method 1

Methodology Applied

Scientific EffectRolling friction reduction: Friction

Data Source

PatentUS9488016B2Spherical ball skate for continuous well string injectors

Publication Date: 2016.11.08 CELTIC MACHINING LTD

AI summary

A skate for an injector apparatus in which gripper dies on a pair of endless chains driven around respective closed loop paths on different sides a continuous wellbore string are forced against the continuous string by forcing a set of the skates toward theretoward from inside the closed loop paths of the endless chains. The inventive skate features a skate body carrying a plurality of spherical balls that are exposed on a side of the skate that faces toward the continuous string in order to allow riding of endless chains over exposed surfaces of the spherical balls as the endless chains are driven through the respective closed-loop paths, whereby the gripper dies ride over the spherical balls of said skates under the forcing of said skates toward the continuous string.