Finite element modelling of rock mass cutting by cutters for PDC drill bits

摘要

A finite element model of the process of polycrystalline diamond compact (PDC) drill bit cutters cutting rocks was built, and the rock linear and circular cutting processes for different shapes of PDC drill bit cutters were simulated. The following initial data was stated before modelling: spatial form of cutter, cutting speed, cutting depth, rheological model of the processed material, and frictional model. Simulation results show that: there is no essential difference between curricular cutting and linear cutting; all the obtained relations of cutting forces were oscillatory and unevenly for all types of cutters; cutting depth increasing causes oscillation amplitude increasing, although no clear relationship between the fluctuations amplitude and the cutting depth is observed for the same cutter; for cutting depth in 0.5 mm and 1.0 mm, the average cutting force decreases when the cutting parameters are stable, while for cutting depth in 2.0 mm, the stable cutting regime is not accompanied by average cutting force decreasing; the cutting forces are smaller for spherical shape cutter and pick-shaped cutter, and bigger for tapered shape cutter and cutters with bevel and flat; the number of peaks per unit time on fluctuation diagram: the minimum value for flat cutter, maximum value for spherical shape cutter.