斧形PDC切削齿破岩机理及试验研究

Rock Breaking Mechanism and Experimental Study of Axe-shaped PDC Cutter

斧形PDC切削齿比常规PDC齿具有更明显的破岩优势。为了分析斧形PDC齿的破岩机理,利用有限元仿真模拟与试验相结合的方法,通过斧形PDC齿与常规PDC齿破岩过程的对比与受力分析,揭示了斧形PDC齿破岩过程的力学机制。分析结果表明:斧形PDC切削齿破碎岩石时,斧刃会使其前方岩石内部形成一个剪应力集中区,岩石更易发生剪切破坏;切削齿斧刃吃入岩石后,屋脊形的斧形齿逐渐楔入岩石,从侧向上使岩石发生拉伸破坏,提高了其破岩效率;斧形齿破岩时所受轴向力和切向力小,更易吃入岩石,所受切向力及轴向力波动幅度更小,具有攻击性及稳定性强的优点,不易发生冲击损坏,在井下使用寿命更长。研究结果可以为新型PDC切削齿的研发和高效PDC钻头的设计及应用提供指导。

Axe-shaped PDC cutter has more obvious rock breaking advantage than conventional PDC cutter.In order to analyze the rock breaking mechanism of the axe-shaped PDC cutter,the finite element simulation and test were used to conduct comparison and force analysis of the rock breaking process of both axe-shaped and conventional PDC cutters,revealing the mechanical mechanism of rock breaking process of the axe-shaped PDC cutter.The analysis results show that when the axe-shaped PDC cutter breaks the rock,the axe blade will form a shear stress concentration area in the rock ahead,and the rock is more prone to shear failure;after the axe blade of the cutter is penetrated into the rock,the ridge-shaped axe-shaped cutter gradually wedges into the rock,forms tensile failure of rock from the side and improves the rock breaking efficiency;when the axe-shaped cutter breaks the rock,the axial force and tangential force applied on it are small,which makes it more easily penetrate into the rock,the fluctuation range of tangential force and axial force is smaller,it has the advantages of strong aggressiveness and stability,impact failure is hard to occur,and the downhole service life is longer.The research results provide guidance for the development of new PDC cutter and the design and application of efficient PDC bit.