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Coal Engineering ›› 2023, Vol. 55 ›› Issue (9): 175-180.doi: 10.11799/ce202309030

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Design of PDC bit for hydraulic reverse circulation continuous coring in underground coal mine

  

  • Received:2023-05-05 Revised:2023-06-19 Online:2023-09-20 Published:2023-11-23

Abstract:

Hydraulic reverse circulation continuous coring technique is an important technology to geological coring drilling construction, and The design of coring bit is an important factor for the successful implementation of reverse circulation. According to the characteristics of hydraulic reverse circulation continuous coring technology in underground coal mine, combined with the principle of hydraulic reverse circulation continuous coring, In this paper, through the design of hydraulic parameters of drill bit, the principle of fluid mechanics is used to allocate the water of drill bit reasonably, which not only ensures the smooth migration of core, but also ensures the smooth discharge of rock powder. The hydraulic parameters of the design are verified by flow field analysis to ensure the rationality of hydraulic parameters.Through the mechanical analysis of the interaction between the clipper and the core, the structural parameters of the clipper are optimized to ensure that the core can be successfully clipped. The cutting structure of the bit is designed, and the blade type circular arc cutter structure is used to ensure that the bit has higher cutting efficiency. Field tests were carried out with the designed drill bit. The test shows that the hydraulic reverse circulation continuous coring bit can meet the flow distribution requirements of cooling drill bit and carrying core, and the comprehensive core taking rate reaches 78%. The drilling efficiency of rock section can reach 7.5-9m/h, and that of coal section can reach 9-18m/h. It meets the requirements of high drilling efficiency, continuous coring during drilling, long pure drilling time and "real time" sampling. This study broadens the application scope of hydraulic reverse circulation continuous coring technology, and provides a drill bit scheme for coring drilling construction in underground coal mine.

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