矿用大直径钻孔连杆式回拉扩孔钻头研发及应用

Development and application of linkage type pull back reaming bit for large diameter borehole in coal mine

针对大直径钻孔成孔存在需多次提钻、钻孔轨迹难以控制、施工效率低的问题,设计了一种可开闭的φ300/153 mm连杆式回拉扩孔钻头,通过调节泥浆泵流量使刀翼在正常钻进过程中处于闭合状态,至目的地层张开实现提钻作业与回扩作业同时进行。详细介绍了连杆式回拉扩孔钻头结构及原理,分析了回拉扩孔钻头开闭机构的力学特性,得到了刀翼所受力矩与切削刀翼张角、曲柄长度、连杆长度和偏心距等因素有关;确定了偏心距及活塞行程,通过理论分析方法得到了使钻头开闭机构具有最佳传力性能的连杆及曲柄尺寸组合以及刀翼所受的推动力矩变化规律;基于自由水射流模型,提出了水流对活塞的推力计算方法,得到了泥浆泵达到最大流量时水流对活塞的推力,并给出了影响切削刀翼张开和复位的关键部件复位弹簧的设计计算。研制的钻头在煤矿井下进行了试验,现场结果表明:φ300/153 mm连杆式回拉扩孔钻头能够实现正常钻进保持φ153 mm钻孔钻进,回拉扩孔时实现φ300 mm钻孔回扩;钻进过程中切削刀翼开闭灵活,钻头钻进稳定、可靠性高,验证了连杆式回拉扩孔钻头结构设计及适用于`普通非联络巷大直径钻孔成孔施工工艺的可行性。

Aiming at the problems of multiple lifting,difficult control of borehole trajectory and low construction efficiency in large diameter borehole,an open and closed 300/153 mm Linkage type Back Reamer was designed. By means of adjusting the flow rate of mud pump,the blade can be closed in the normal borehole process and opened in the target layer,so that the lifting operation and backexpanding operation can be carried out simultaneously.This paper introduces in detail the structure and principle of Linkage type Back Reaming Bit,analyzes the mechanical characteristics of the opening and closing mechanism of the Reamer,and obtains that the torque of the blade is related to the opening angle of the cutting blade,the length of the crank,the length of the connecting rod and the eccentricity. The eccentricity and the piston stroke were determined,and the optimal force transmission performance of the opening and closing mechanism of the drill bit was obtained by theoretical analysis Based on the free water jet model,the thrust calculation method of water flow on piston was proposed,and the thrust force of water flow on piston is obtained when the mud pump reaches the maximum flow rate,and the design calculation of the key component reset spring which affects the opening and reset of cutting blade wing is given. The Linkage type Back Reamer has been tested under the coal mine and the results showed that: the φ300/153 mm rod type pull back reaming bit can achieve normal borehole,maintain the φ153 mm borehole,and realize the φ300 mm hole expansion when pulling back to expand the hole;the cutting blade is flexible in opening and closing,the borehole bit is stable and reliable,which verifies the feasibility of the structure design of the Linkage type Back Reamer and the construction technology suitable for large diameter borehole in common non-contact roadway.