In order to improve hard rock breaking efficiency in coal mines, a new inner cone PDC bit is designed, the rock breaking process of inner cone PDC bit is simulated, and its mechanical characteristics is analyzed.Simulation results show that, comparing with the regular concave PDC bit, the axial force needed by inner cone PDC bit reduces by up to 13%, and the rock breaking efficiency increases nearly 30% under the same working condition;the imbalanced radial force accounts for 9.8% of axial force, which is easy to cause bit whirl, so it must focus on the lateral force balance design of inner cone PDC bit.Also, Φ94 mm steel inner cone PDC bit is made, field drilling test results show that: the bit life expectancy increases about two times, and the rock breaking efficiency increases more than 40% comparing to the regular used steel concave PDC bit.All of these show that, the new inner cone PDC bit can help to reduce drilling cost, and improve rock breaking efficiency.%为提高煤矿井下硬岩钻进破岩效率,设计了Φ94 mm内锥型PDC钻头;并对其进行了破岩过程仿真分析,以研究其受力特性.结果表明:与相同规格三翼内凹PDC钻头相比,在同等工况条件下,内锥型聚晶金刚石复合片箭头(polycrystalline diamond compact bit,PDC)所需轴向载荷降低近13%,破岩效率提高近30%;内锥型PDC钻头破岩受到的径向不平衡力占钻压的9.8%,钻头容易产生涡动;因此对于内锥型PDC钻头应关注其侧向力平衡的设计.根据分析结果,试制Φ94 mm钢体内锥PDC钻头并进行现场试验,相比于工区现用Φ94 mm普通钢体三翼内凹PDC钻头,试验钻头平均寿命提高2倍左右、破岩效率提高40%以上,表明研制的新型内锥PDC钻头有助于降低钻进成本,提高破岩效率.
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