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Coal Engineering ›› 2025, Vol. 57 ›› Issue (12): 104-110.doi: 10.11799/ce202512014

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Synchronous Double-Thread Anti-Drop Technology for Mining Drill Pipes

  

  • Received:2025-08-20 Revised:2025-10-04 Online:2025-12-11 Published:2026-01-26

Abstract:

To address the issue of drill pipe joint fractures leading to dropped drills, this paper analyzes the mechanism behind thread fractures and subsequent drill drops, proposing a synchronous double-thread anti-drop technology. The design incorporates a synchronous double-thread + connecting rod structure, where the main thread bears the load, and the secondary thread and connecting rod maintain axial connection to prevent tool detachment. The design concept of the synchronous double-thread pin and box joints is introduced, along with calculation methods for the main thread's load-bearing capacity and the anti-drop capability of the secondary thread and connecting rod. Performance tests were conducted on Φ89mm double-thread drill pipes, demonstrating a torsional resistance of 34904 N?m and a tensile resistance of 1878 kN—2.33 times and 6.26 times the rated capacity of the matching drill rig, respectively. Simulated secondary tensile resistance after pin and box thread fractures reached 517 kN and 433 kN, 1.72 times and 1.44 times the rig's rated pulling force, fully meeting safe drill retrieval requirements. The test results confirm that the synchronous double-thread structure effectively resolves the problem of drill drops caused by joint fractures, significantly enhancing drill pipe reliability and operational safety.

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