PDC钻头综合受力模型的试验研究

Experimental research on integrated mechanical model of PDC bit

模拟钻头上的切削齿的不同的切削断面形状、重叠切削状态及磨损状态,利用PDC切削齿对多种岩样进行了切削试验,研究了切削面积、接触弧长、切削齿后倾角、岩石抗钻强度、切削齿磨损高度等因素对PDC切削齿受力的影响规律。结果表明,切削面积相同情况下切削齿受力随接触弧长、岩石可钻性极值、切削齿磨损高度分别呈线性,幂函数和指数函数趋势变化;切削齿受力最小的后倾角在5～10°区间内。引入弧长系数、磨损高度系数,建立了PDC切削齿综合受力模型。根据力的平衡原理,推导得出完整的PDC钻头受力计算模型,为PDC钻头优化设计和合理使用提供了理论依据。

The cutting tests on various rocks were carried out using PDC cutters with simulating the shape of cutter section, the worn state of cutter and the state of lapping cutting. The factors, which include cutting area, contact arc length, back rake angle, rock strength against drilling and worn height of cutter, on the forces on PDC cutter were analyzed. Under a constant cutting area, the force on cutter changes with radian coefficient by the relationship of linear, rock strength against drilling by the relationship of power function, and worn height coefficient by the relationship of exponential function. It is found that the force on PDC cutter is the minimum when back rake is about 5-10 degrees. The conceptions of radian coefficient and worn height coefficient were introduced. Based on them, the general mechanical model of PDC cutter is built. Using balance equation of force, the integrated mechanical model of PDC bit is built for force calculation, which offers theoretical basis for bit design optimization and reasonable use.