Transient dynamics of impact rock drilling and its efficiency analysis

On the basis of analyzing the rock crushing process of impact rock drilling,the transient dynamic analysis was conducted with drilling theory of wave dynamics for the impact drilling system of a drill composed of piston-drill rod-rock.Based on one-dimensional and two-dimensional dynamic model of impact subsystem,the characteristic equation of rock drilling system was set up.Abstracted variables such as non-dimensional mass-ratio of drill bit and non-dimensional length-ratio of piston were introduced to derive the expression for energy transfer efficiency of the system.A detailed analysis of transmission efficiency of stress wave in the drill rod was carried out,so that the maximal drilling efficiency was obtained for the cases of different design parameters.