预警—牙轮防脱落技术的发展方向

CONE-LOSING INDICATOR REPRESENTS DIRECTION OF CONE RETENTION TECHNIQUE

提高牙轮钻头防止牙轮脱落的能力 ,可以显著减小牙轮脱落事故的发生率 ,因而对降低钻井成本以及提高钻头使用效率具有重要意义。综述了国内外牙轮锁紧技术的发展历史和现状 ,简要介绍了几种典型锁紧结构 (钢球结构、卡簧结构、螺纹环结构以及R槽钢球憋卡预警结构等 )的工作原理和技术特点。指出牙轮脱落的预警是牙轮防脱落技术的发展方向。分析了牙轮脱落预警的技术关键、难点以及已有预警技术的优缺点。提出了一种以扭矩显著增加、钻速显著降低为预警信号的新的牙轮脱落预警技术 ,并对该技术的预警机理以及研究情况作了简要的分析和阐述。试验证明 ,该技术能准确监测轴承的磨损状态 ,在磨损量达到警戒限值时能可靠地自行启动 。

Decreasing the probability of cone losing of rock bit by improving the cone retention technique, it should have quite significant effect on reducing cost of drilling and increasing bit utilizing efficiency. This paper summarized the development history of cone retention or cone locking technique of rock bits. Principles and characteristics of several typical configurations,ball retainer, snap ring retainer, threaded ring retainer, and trapped ball cone losing indicator, were described respectively. A new cone losing indicator design, trapped rollerindicator, which utilizes the sharp changes of both twisting moment and ROP of bit as alarm signal, was introduced and analyzed. The simulative drilling test have proved that this new technique have an ability to inspect the bearing clearance exactly, and the trapped roller will increase the twisting moment and decrease the ROP of bit by locking the cone automatically when the critical clearance is reached.