Effects of nozzle position and waterjet pressure on rock-breaking performance of roadheader

The performance of roadheaders in cutting hard rocks can be improved using high-pressure waterjet technology. The optimum position of waterjet nozzles and the threshold pressure in rotary cutterheads have not been well studied. This study investigates the effects of the waterjet-nozzle position and waterjet pressure on the cutting torque and thrust force of scaled roadheaders with point-attack picks. The experimental results show that the waterjet helps in significantly reducing the cutting torque and thrust force. Moreover, the rock-breaking performance is the best when the nozzles are positioned at the center of the pick. For the center-positioned configuration with a pressure of 40 MPa, the specific energies of three types of rocks are reduced by 41.3, 28.3, and 20.1%. The effects of the nozzle position and waterjet pressure on the dust suppression and pick wear are also examined and a fine-dust suppression coefficient of over 70% is achieved.