多脊PDC切削齿破岩有限元仿真及其几何结构影响

Rock breaking simulation and optimization design of multi-ridged PDC cutters

针对脊高为0~5 mm、脊角为115°~172°的多脊齿开展固定切削深度的旋转切削破岩数值模拟研究。分析多脊齿几何结构对切削力、地层吃入性能、机械比能的影响规律,并且在研究多脊齿机械比能时考虑轴向力的影响。结果表明:随着脊角变小,多脊齿的切削力减小,地层吃入性能增加,126°脊角的多脊齿吃入地层轴向力较平面齿低41%,最佳切削深度为2 mm;机械比能方面轴向上消耗的比能是切向的1.2~1.5倍,且脊角的小角度改变对机械比能影响甚微;特殊几何结构下多脊齿更易出现接触应力集中,并在旋转时出现侧向力,当脊角大于151°且多脊齿切削半径大于28 mm时破岩效果最佳。

In this paper,the numerical simulation of rock breaking by rotary cutting with fixed cutting depth was carried out for multi-ridged cutters with ridge height of 0-5 mm,ridge angle of 115°-172°.The influence of axial force was considered when calculating the mechanical specific energy(MSE)of the multi-ridged cutter.The geometric influence of the multi-ridged cutter on cutting force,formation penetration ability and the MSE was analyzed.The results indicate that the cutting force of the multi-ridged cutter decreases with the reduction of the ridge angle,but its penetrating ability improves.The axial force for the multi-ridged cutter with a ridge angle of 126°to penetrate the formation is 41%lower than that of a plane cutter.It is found that the optimal cutting depth is 2 mm.The axial MSE is 1.2-1.5 times larger than the tangential MSE,and a small change of the ridge angle has little effect on the MSE.The special geometry of the multi-ridged cutter can be prone to stress concentration and can induce a lateral force during rotation.The analysis of the forces on the inner and outer sides of the multi-ridged cutter shows the rock breaking efficiency is higher when the edge angle is above 151°and the cutting radius of the multi-ridged cutter is greater than 28 mm.