Collet Mechanism Drag Force Reduction in Mechanical Jar
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Frictional drag between the collet and mandrel in mechanical jars used for releasing stuck objects in wells significantly reduces the efficiency of mechanical impulse and retards the resetting process, necessitating a method to decrease contact force between these components.
Innovation Solution
Incorporating an auxiliary spring that relieves the axial force from the main spring, transferring it to a trigger sleeve with a lower exertion force, thereby reducing the drag force on the mandrel during both firing and resetting stages by using a collet mechanism with sloped cylindrical protrusions and grooves to minimize contact force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a collet mechanism is used to restrain and release the mandrel, then the jar can store and release mechanical energy effectively, but frictional drag between the collet and mandrel reduces the mechanical impulse efficiency
Solution Approach 1:
The patent changes the physical state of the collet by introducing a phase transition mechanism. The collet transitions between a expanded (restrained) phase and a contracted (released) phase, allowing the mandrel to move with minimal frictional drag during the release stroke while maintaining effective restraint during the loading phase.
Solution Approach 2:
The patent introduces an intermediary mechanism (the phase-transitioning collet) between the mandrel and the housing that mediates the transfer of mechanical energy. This intermediary allows the mandrel to be restrained during loading and then released smoothly during the impact stroke, reducing direct frictional contact.
2Reliability
If the collet maintains strong contact force with the mandrel, then the mandrel is effectively restrained during energy storage, but the frictional force retards the resetting process
Solution Approach 1:
The patent applies dynamics by making the collet's contact force variable rather than static. The collet dynamically adjusts its expansion state based on the operational phase: expanded during loading to provide strong restraint, and contracted during resetting to minimize friction and allow rapid return of the mandrel.
Solution Approach 2:
The collet undergoes periodic phase transitions synchronized with the operational cycle of the jar. It alternates between restrained and released states, providing strong contact force during energy storage and minimal contact force during resetting, thereby improving both reliability and productivity.
3Loss of energy
If lubricating coatings or fluids are used to decrease frictional force, then drag force is reduced, but the device complexity and maintenance requirements increase
Solution Approach 1:
The patent replaces the traditional mechanical lubrication system with a phase-transition-based mechanical solution. Instead of using lubricating coatings or fluids to reduce friction, the collet's phase transition mechanism inherently minimizes frictional contact during the release and resetting phases through geometric and mechanical design.
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 reduces the drag force on the mandrel to less than 4.53 kg (10 lbs), enhancing the mechanical impulse and accelerating the resetting process, improving the overall efficiency of the jar mechanism.
Implementation Method 1
Incorporating an auxiliary spring that relieves the axial force from the main spring, transferring it to a trigger sleeve with a lower exertion force
Implementation Method 2
using a collet mechanism with sloped cylindrical protrusions and grooves to minimize contact force
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3
AI summary
Method and apparatus for decreasing drag force in a mechanism for releasing a mandrel is provided. The mandrel is released by a collet, which is controlled by a trigger sleeve. Most of the axial force on the collet is relieved, thereby decreasing the frictional force exerted by the collet on the mandrel after it is released.