Burnishing Device for Small Diameter Pipe Threads
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Solution Overview
Problem
Existing cold root-rolling devices are not adapted for use with smaller diameter threaded pipes, which are commonly used in on-shore gas drilling operations, limiting their application and effectiveness in enhancing the fatigue life and integrity of threaded connections.
Innovation Solution
A device with a body, lever, accumulator piston, and roll holder configuration that allows for controllable force application and precise pressure measurement, enabling effective cold root-rolling of smaller diameter pipes by using a self-contained pressurization system and asymmetric roll holder for accurate roll alignment and engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing cold root-rolling devices are used on smaller diameter threaded pipes, then the device cannot be properly installed or operated, but modifying the device increases complexity and reduces adaptability
Solution Approach 1:
The patent applies local quality by designing a compact pressurization system specifically tailored for smaller diameter pipes. The self-contained hydraulic system with integrated accumulator and pump allows the device to adapt to smaller dimensions without requiring complete redesign of the entire structure. The roll holder and application head are specifically configured for small diameter engagement, while the overall device maintains a manageable complexity level through localized optimization rather than global redesign.
2Measurement precision
If a self-contained pressurization system is implemented, then force control precision is improved, but device size and complexity increase
Solution Approach 1:
The patent merges the pressurization system components into a self-contained integrated unit. The hydraulic pump, accumulator, valves, and gauges are combined within a single housing structure that attaches to the drill string. This merging approach provides precise force control through the closed-loop hydraulic system while avoiding the complexity of multiple separate systems. The integration allows for coordinated operation of all pressurization elements without requiring external systems or complex interconnections.
3Manufacturing precision
If an asymmetric roll holder is used for accurate roll alignment, then burnishing precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs asymmetry in the roll holder design to achieve accurate roll alignment with the thread profile. The roll holder features an asymmetric geometry that naturally guides the roll into the correct orientation during installation. This asymmetric design provides precise alignment without requiring complex adjustment mechanisms or multiple machining operations. The asymmetric shape is manufactured as a single integrated component, which actually simplifies the manufacturing process compared to using symmetric components with multiple adjustment elements.
4Reliability
If cold root-rolling is applied to increase fatigue life, then connection reliability is improved, but the process time and complexity increase
Solution Approach 1:
The patent implements continuous useful action by designing a cold root-rolling device that can operate continuously as the drill string is assembled or maintained. The self-contained pressurization system provides continuous hydraulic pressure, allowing the roll to continuously burnish the thread surfaces without interruption. The device can be left in place during drilling operations, providing ongoing fatigue life enhancement without requiring separate processing steps. This continuous operation significantly reduces the total time compared to batch processing methods while maintaining high reliability improvements.
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 device effectively increases the fatigue life of smaller diameter threaded connections by applying consistent burnishing force, reducing the risk of downhole failures and enabling early detection of potential issues in drill-strings, thus reducing repair costs and frequencies.
Implementation Method 1
The hydraulic system is pressurized to a selected level, sufficient to force the roll into engagement with the pipe surface
Implementation Method 2
Pressure is applied to cause the hardened roll to penetrate into the surface of the thread. This deforms and cold-works the material
Implementation Method 3
Cold root-rolling creates a thin zone of residual compressive stress in the root region of the thread. This residual compressive stress may offset tensile stresses produced in service
Implementation Method 4
The burnishing effect of the smooth and hardened roll causes small scratches and ridges left by the thread-cutting operation to flatten into a more-uniform surface
Implementation Method 5
Cold root-rolling has a work-hardening effect of the surface of the material. This increased resistance to further deformation helps to prevent cracks from starting
Data Source
AI summary
Devices (10) for burnishing a surface (111, 112) on an object (108) includes a body (11) having a passageway (25), an accumulator piston (65) mounted on the body for sealed sliding movement within the passageway, a coarse adjustment screw (13) mounted on the body, a resilient member (14) acting between the coarse adjustment screw and the accumulator piston, a lever (12) mounted on the body, a chamber (32) communicating with the accumulator piston, an actuator piston (78) mounted on the body for sealed sliding movement within a cylindrical opening (41) toward and away from the rearward portion (48) of the lever, and a roll (15) rotatably mounted on the forward portion (49) of the lever. The devices are adapted to be mounted on a machine tool (105) and moved toward the object to burnish the surface with controllable force along the required length of the surface.