Elliptical design of male thread clearance

By adopting an elliptical transition section design in the transition area between the male casing and the main length section of the drill pipe, the fatigue and fracture problems caused by stress concentration were solved, thereby extending the service life of the drill pipe and enhancing its load-bearing capacity.

CN115103951BActive Publication Date: 2026-07-21SANDVIK MINING & CONSTR TOOLS AB
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Patent Information

Application Number
CN202180014321.5
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Priority Date
2020-03-11
Filing Date
2021-03-10
Publication Date
2026-07-21
Estimated Expiration
2041-03-10

AI Technical Summary

Technical Problem

The male casing of existing drill pipes is prone to fatigue and cracking in the transition area due to stress concentration, resulting in a shortened connection life and an inability to effectively withstand large bending moments and tensile loads.

Method used

Design a drill string that optimizes stress concentration, enhances stiffness, and reduces fatigue and fracture risk by using an elliptical transition section in the transition area between the male casing and the main length section. This includes the design of the elliptical transition section to reduce stress concentration.

Benefits of technology

It extends the service life of drill pipes, enhances their ability to withstand large bending moments and tensile loads, and reduces the risk of breakage.

✦ Generated by Eureka AI based on patent content.

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Abstract

A drill string comprising: an elongate hollow main length section (101); a male casing portion (108) provided at a second end (106), the male casing portion having an externally threaded section (107) and a non-threaded shank (109) axially positioned intermediate the main length section (101) and the threaded section (107); the shank (109) having a transition section (206) positioned adjacent a radially protruding shoulder (110) at the second end (106) or the main length section (101), the transition section (206); wherein a cross-sectional shape profile of an outer surface of the transition section (206) in a plane of a longitudinal axis (204) comprises a segment of an ellipse having a semi-major axis (a), a semi-minor axis (b); wherein a ratio of the semi-major axis to the semi-minor axis (a:b) is within a range 2b
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Citation Information

Patent Citations

  • Fatigue resistant rotary shouldered connection and method

    EP1705415A2

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    EP2845991A1

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    GB2321073A

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    US1926925A

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    US4332502A