Evaluation on cutting performance of novel PDC cutter for pipe jacking machine

Abstract

It is inevitable to cut reinforced concrete (RC) appeared in cross passage of city metro by cutting tools when constructing in densely populated area. The previous cutters employed to cut RC are insufficient and easily damaged, so a new polycrystalline diamond compact (PDC) cutter is used to solve this question. Based on the theoretical analysis of cutting mechanism, both circular and tapered PDC cutters with cutting edge angle of 90° and negative front rack angle of 10° are used to cut RC. The peeling and breaking patterns of cutting concrete are proposed, the nodular and grainy chips are the preferred modes in cutting steel bars. The LS-DYNA is employed to investigate the cutting performance in advance. The simulation results show that the average and peak cutting forces increase with the growth of penetration depth, cutting speed, and roundness, and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel bars. Moreover, the linear cutting platform is adopted to investigate the force ability and damage state of PDC cutters. It is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse aggregates. The patterns occurred in both numerical and experimental results are generally similar. Notably, the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm, while a good cut occurs at the penetration depth of 0.3 mm. The tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC cutter. It is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.