Segmented Threaded Pipe Connection for High Torque and Faster Machining
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Solution Overview
Problem
Existing threaded connections for steel pipes require extensive machining time due to varying thread widths along the entire length, leading to increased risk of shear fracture under tensile loads and inefficient torque transmission.
Innovation Solution
A threaded connection design featuring a combination of constant and varying thread widths, where the constant-thread-width portions maintain consistent groove and ridge widths, reducing machining time and preventing shear fractures, while the varying-thread-width portions enhance torque by gradually increasing groove and ridge dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the thread-groove width changes over the entire thread length with a non-constant rate of change, then the torque of the threaded connection is improved, but the number of cutting passes increases significantly and machining time increases
Solution Approach 1:
The thread length is divided into two distinct segments: a first segment with a constant rate of change in thread-groove width, and a second segment with a different constant rate of change. This segmentation allows each portion to be optimized independently, reducing the overall machining complexity while maintaining the torque-enhancing varying width profile throughout the thread length.
2Power
If the thread-ridge width varies along the entire thread length, then the torque is improved, but the minimum thread-ridge width at the end becomes very small causing shear fracture under tensile load
Solution Approach 1:
The thread structure is segmented into two portions along the thread length, with each portion having different width variation characteristics. The first portion has a gentler rate of width change that maintains adequate thread-ridge width for strength, while the second portion has a steeper rate that maximizes torque. This prevents the minimum thread-ridge width from becoming too small and causing shear fracture.
Solution Approach 2:
Different sections of the thread are given different local properties: the first portion maintains larger dimensions for strength and stability, while the second portion has more aggressive width variation for enhanced torque transmission. This local differentiation allows the thread to simultaneously achieve both high torque and adequate tensile strength.
3Power
If the difference between minimum and maximum thread-groove width is large, then the torque capacity is improved, but the number of cutting passes increases and manufacturing complexity increases
Solution Approach 1:
The thread-groove width variation is segmented into two phases with different constant rates of change. The first phase covers the initial portion of the thread with a moderate rate of change, while the second phase covers the remaining portion with a different rate. This segmentation enables the large overall width difference to be achieved through controlled, manageable increments, reducing the number of cutting passes required.
Data Source
AI summary
A threaded connection connecting a pair of pipes includes a pin and a box. The pin has a male thread on its outer diameter. The box has a female thread on its inner diameter, the female thread corresponding to the male thread. The male thread includes constant-thread-width and varying-thread-width portions. The constant-thread-width portion has a constant thread-groove width. The varying-thread-width portion has a thread-groove width equal to or larger than the groove width of the constant-thread-width portion and gradually increasing, from the constant-thread-width portion toward the tip of the pin. The female thread includes constant-thread-width and varying-thread-width portions. The constant-thread-width portion has a constant thread-ridge width. The varying-thread-width portion has a thread-ridge width equal to or larger than the thread-ridge width of the constant-thread-width portion and gradually increasing from the constant-thread-width portion toward the center of the box.