锯齿形PDC刀具的破岩特性及温度场

Rock Breaking Characteristics and Temperature Field of Serrated PDC Cutter

聚晶金刚石复合片(polycrystalline diamond compact, PDC)刀具的结构是影响钻头性能的重要因素,锯齿形PDC刀具性能较好但研究较少,缺乏相关理论支撑。因此,基于弹塑性力学及Drucker-Prager准则构建了刀具与岩石的有限元模型,对锯齿形PDC及常规PDC刀具的破岩和温度场进行对比研究。结果表明,锯齿形PDC通过剪切和犁碎的方式破岩,有效且明显提升了破岩效率。锯齿形PDC较常规PDC切削力均值减小约20%,波动明显更小。后倾角变大,其切削力增加,破岩比能先增加减小又增加,存在最佳后倾角10°~15°;切削深度增大,切削力变大,破岩比能先减小后增加,存在临界切深1.5~2 mm;锯齿数增加,刀具的切削力与破岩比能先增加后减小,3个锯齿为最佳。温度场研究结果表明,锯齿形PDC比常规PDC刀具散热面积大,热稳定性更好,工作参数与温度变化之间存在规律。研究深度揭示了锯齿形PDC刀具的破岩特性以及温度场,对PDC刀具优化及高性能钻头布齿具有较为重要的指导意义。

The structure of polycrystalline diamond compact(PDC)cutter is an important factor affecting the performance of the drill bit.The serrated PDC cutter has good performance but less research,and lacks relevant theoretical support.Therefore,based on elastoplastic mechanics and Drucker-Prager criterion,the finite element model of cutter and rock was constructed,and the rock breaking and temperature field of serrated PDC and conventional PDC cutter were compared.The results show that the serrated PDC effectively and significantly improved the rock breaking efficiency by shearing and ploughing.The mean cutting force of serrated PDC was about 20%lower than that of conventional PDC,and the fluctuation was obviously smaller.When the back rake angle became larger,the cutting force increases,and the specific energy of rock breaking increased first,then decreases and increased again.There was an optimal back rake angle of 10°~15°.With the increase of cutting depth,the cutting force increases,and the specific energy of rock breaking decreases first and then increases.There was a critical cutting depth of 1.5~2 mm.As the number of serrations increases,the cutting force and rock breaking specific energy of the cutter increase first and then decrease,and the three serrations were the best.The results of temperature field research show that the serrated PDC has a larger heat dissipation area and better thermal stability than the conventional PDC cutter,and there is a law between working parameters and temperature changes.The research depth reveals the rock breaking characteristics and temperature field of the serrated PDC cutter,which has important guiding significance for PDC cutter optimization and high-performance bit tooth arrangement.