Effect of crack prefabrication by self oscillating pulsed jet on the temper ature of conical pick during rock breaking processes

To solve the problem of wear increase of conical pick in the process of hard rock roadway excavation,the influence of different self-oscillating nozzle structure parameters (cavity length,cross section cone angle) and working parameters (system pressure,transverse speed) on load reduction and wear reduction of conical pick were studied based on high pressure water jet rock breaking system and rock cutting test system.In addition,the cutting load of conical pick was analyzed under the crack prefabrication by self oscillating pulsed jet (SOPJ).The experimental results show that the cutting load and tool temperature decrease with the increase of the water pressure,increase first and then decrease with the increase of cavity length and section cone angle,and increase gradually with the increase of transverse speed.When the system pressure is 30,40,50 and 60 MPa,the cutting load reduction rates of mechanical tools are 15.12%,20.84%,27.01% and 29.24%,respectively.When the cone angle of section is 90°,120°,140°,160° and 180° respectively,the change rate of cutting load is reduced by 22.87%,27.27%,31.13%,33.82% and 29.78% respectively.For the transverse speed of 4,6,8,9 and 10 m/min,the change rate of cutting load is reduced by 43.6%,35.3%,32.9%,31.1% and 30.7%,respectively.When the water pressure,cavity length,cross section cone angle and the transverse speed are 50 MPa,65~75 mm,140°~160° and 6~8 m/min respectively,the rock breaking performance of conical pick is better.