Cam-Actuated Latch for Ground Drill Retraction
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Solution Overview
Problem
Existing latch arrangements in drilling mechanisms require significant initial axial force to retract the inner tube assembly, leading to potential latch damage and inefficiency in wire line drilling applications.
Innovation Solution
A locking mechanism featuring a cam and cam follower system that optimizes the leverage and movement of latches, allowing for easier retraction of the insertable device from the outer tube by translating axial force into transverse force, reducing the initial force required and minimizing latch damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional latch arrangements are used to lock the inner tube assembly, then the latch can reliably retain the insertable device in a fixed position, but a great initial axial force is required to release and retract the latch
Solution Approach 1:
The invention introduces a cam surface with a curved profile that converts the axial retraction force into a transverse force component. The cam surface is configured with a specific curvature that provides mechanical advantage, allowing the latch to be withdrawn from the latch seat with reduced axial force. The curved cam surface creates a force transformation mechanism where the initial axial pull is converted into an effective transverse force that leverages the latch away from the engagement surface.
2Strength
If the latch is forced tightly against the seating shoulder during drilling, then the latch can withstand considerable load, but the latch requires a lot of force to retract
Solution Approach 1:
The invention changes the force application parameters by introducing a cam mechanism that transforms the retraction force vector. Instead of directly opposing the strong engagement between the latch and seating shoulder, the cam surface is designed to create a mechanical advantage that multiplies the effective force. The cam profile parameters (curvature, angle, position) are optimized to provide sufficient leverage to overcome the tight engagement while maintaining the latch's load-bearing capacity during drilling operations.
3Device complexity
If a simple latch mechanism is used, then the device complexity is reduced, but the initial force required to retract the latch is great
Solution Approach 1:
The invention introduces a cam surface as an intermediary element between the latch and the retraction force application point. This cam surface acts as a force transformer that mediates between the simple axial pull and the complex requirement of withdrawing a tightly engaged latch. The cam surface is a relatively simple geometric feature that can be integrated into the existing latch structure, providing force multiplication without significantly increasing overall device complexity.
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 mechanism enables the insertable device to be easily retracted with reduced axial force, enhancing operational efficiency and minimizing the risk of latch damage during the transition from an expanded locking to a retracted position.
Implementation Method 1
the cam presents a withdrawal surface, against which a cam follower is arranged to slide to cause the latch to withdraw to unlock the insertable device from the outer tube
Data Source
AI summary
A locking mechanism for locking an insertable device relative to an outer tube of a ground drill comprises at least one latch, which is arranged to releasably retain the insertable device in a substantially fixed axial position relative to the outer tube. The locking mechanism comprises a cam and a cam follower, which are arranged to control a radial position of the latch. The locking system may be used in a ground drill system.