Interlocked Thread Connector for High Torque Transfer
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Solution Overview
Problem
Existing mechanical connectors, such as those in the Merlin™ family, face limitations in handling high torsional loads and fatigue due to their design, which affects their performance in offshore engineering applications where high torsional and bending loads are prevalent.
Innovation Solution
The introduction of structural features like dog-clutch teeth, fitted pins, keys, splines, and interlocked thread systems, combined with modifications in the shapes of boxes and pins, and the use of assembly/disassembly fluids that solidify, enhances the connectors' ability to manage high torsional loads and improve stiffness and weight control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional Merlin™ family connector design is used, then axial and bending load capacities are high, but torsional load capacity is limited and difficult to control accurately
Solution Approach 1:
The connector is divided into distinct functional segments: the box and pin components, threading sections for axial load transfer, and separate torque transfer mechanisms (such as keyways, splines, or dog-clutch teeth). This segmentation allows each segment to be optimized for its specific function, enabling high torsional capacity without compromising axial performance.
Solution Approach 2:
The connector design incorporates asymmetric features such as non-circular keyways, splined interfaces, or dog-clutch tooth configurations that provide superior torsional load transfer compared to symmetric circular interfaces. These asymmetric geometries create mechanical interlocking that resists rotational forces while maintaining axial alignment.
2Strength
If box outside stress diameters and pin inside stress diameters are kept substantially constant, then manufacturing is simplified, but torsional load capacity and stiffness are limited
Solution Approach 1:
The connector design implements varying diameters at different locations: constant stress diameters in regions requiring uniform strength, and variable diameters in regions requiring enhanced torsional capacity or stiffness. For example, the pin may feature a larger diameter at the torque transfer interface while maintaining a standard diameter in the threading region, allowing localized optimization without compromising overall manufacturing feasibility.
3Ease of operation
If assembly/disassembly pressures are reduced, then ease of operation improves, but connection reliability may be compromised
Solution Approach 1:
The design incorporates intermediary features such as tapered threading sections, cam-actuated locking mechanisms, or elastomeric sealing elements that facilitate smooth assembly and disassembly at reduced pressures. These intermediaries act as mediators between the operational requirement for easy assembly and the reliability requirement for secure connection, allowing low-pressure operation while maintaining connection integrity through mechanical interlocking and progressive engagement.
Data Source
AI summary
This invention builds up on technical features and on the industry experience with the use of Merlin™ family connectors. In addition to friction, structural means utilized to transfer high torsional loads include interlocked thread systems and may also include: dog-clutch teeth, shear pins, keys and splines, all used in isolation or in arbitrary combinations. Static and fatigue bending load capacities of the connectors remain high, while the axial load capacities may or may not be high, depending on the design requirements. Connectors according to this invention can be built as new, carefully optimized designs. In some cases upgrading existing Merlin™ family connector designs to increase they torque transfer capacities may be also feasible.