Mechanical Door Switch and Centering Tab for Hydraulic Power Tongs
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Solution Overview
Problem
Power tongs in the oil and gas industry pose safety hazards due to the risk of pinching from rotating components, and existing safety mechanisms are inadequate, especially in environments where electronics cannot be used due to fire hazards from high-pressure oil flows.
Innovation Solution
A door switch mechanism for power tongs that automatically disconnects the hydraulic supply to the motor when the door is opened, using a biasing mechanism and a moveable component to ensure the motor stops operating if the door is not fully closed, and a tab with varying edge sizes for precise alignment of tubulars within the tong.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a door switch mechanism is implemented to prevent motor operation when the door is open, then operator safety is improved, but device complexity increases
Solution Approach 1:
The patent replaces electronic switches with a purely mechanical door switch mechanism. The moveable component, cable, and valve control assembly create a mechanical linkage that automatically disconnects hydraulic supply when the door opens, eliminating the need for electronic components while achieving the safety function.
Solution Approach 2:
The patent introduces a mechanical intermediary system consisting of the moveable component within the bore and the cable that translates door position into hydraulic supply control. This intermediary mechanism physically couples the door position to the hydraulic valve control, enabling automatic disconnection without electronics.
2Ease of operation
If electronic switches are used to control motor operation, then ease of operation is improved, but safety deteriorates due to fire hazard from high-pressure oil flow
Solution Approach 1:
The patent eliminates electronic components entirely by using a mechanical door switch mechanism that directly controls hydraulic supply through physical movement of the cable and valve control assembly. This mechanical system is inherently safe in high-pressure oil environments where electronics would pose fire hazards.
3Ease of operation
If manual alignment of tubulars is performed, then ease of operation is maintained, but productivity decreases due to time waste and repeated re-alignment
Solution Approach 1:
The patent implements a centering tab that pre-positions the tubular within the ring gear assembly before the biting operation begins. The tab with its specific geometry (edges at different distances from the center) automatically guides the tubular into correct alignment, eliminating the need for manual adjustment during operation.
Solution Approach 2:
The centering tab enables the system to self-align the tubular through its geometric design. The tab's edges at varying distances from the center create natural contact points that guide the tubular into the correct position without requiring operator intervention, making the alignment process automatic and repeatable.
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
Enhances operator safety by preventing motor operation when the door is open and facilitates precise alignment of tubulars, reducing the need for manual re-alignment and minimizing operator risk during well operations.
Implementation Method 1
the biasing mechanism comprises a spring configured to bias the piston against the door when the door is in the closed position
Implementation Method 2
the ring gear assembly is driven by a motor having a hydraulic supply
Data Source
AI summary
A door switch is suitable for use with a power tong having a door mounted on a tong body to close a throat. The door switch includes a moveable component that is in operational contact with the door and a valve control. The moveable component is biased into contact with the door when the door is in a closed position. The biasing mechanism biases the moveable component to move axially when the door is at least partially open to cause a valve to disengage a hydraulic motor supply. The moveable component disengages from the door when the door is at least partially open. A tab for the power tong has a plurality of edges, each edge defining a smallest distance from a center of a through hole to the respective edge, and each of the smallest distances of each edge being different in size.