Research on rock breaking characteristics of impact hob of hard rock excavator

Abstract

During hard rock excavation in the process of tunnel construction, the hard rock excavator wears seriously and quickly and reduces its excavation efficiency. Aiming at this problem, this paper proposes a composite rock breaking method by impact rolling and cutting as a solution. In this paper, the composite rock breaking characteristics of impact hob are studied. The impact cutting load of the hob was analyzed, and the hobbing force equation and the rock crushing volume equation were established. The effects of different impact frequencies and impact loads on the cutting force and rock crushing characteristics of the hob were analyzed by experiments. The results show that under a certain thrust and hob spacing, with the increase of the impact frequency, the rock ridge between the two hobs gradually decreases, while the crushed volume of the rock increases gradually. Under the same axial load and cutter spacing conditions, with the increase of the impact frequency, the hob shear force decreases significantly. Under a certain axial load and impact frequency, with the increase of impact load, the crushing volume of rock and the hob shear force decrease significantly. These test results are of great significance for guiding the efficient excavation of hard rock tunnels.

The Effects of High-Energy Composite Surface Layer Modification on the Impact Performance of the H13 Steel Cutter Ring for Shield Tunneling Machine

“…The hob applies force to the rock in three directions during rock breaking. These forces include the normal thrust provided by the thrust of the cutterhead, the tangential rolling force provided by the cutterhead rotation, and the lateral force produced by the centrifugal effect of the hob squeezing the rock and the cutterhead rotation [15]. Relatively, the rock produces counter-forces in three dimensions on the hob, as shown in Figure 1, in which Fr is the resistance in the direction of rolling of the hob, Fl is the counter-force of lateral pressure, and Fn is the normal counter-force.…”