Research On Arrangement Of Pick Working Angle And Rock Breaking By Cutting Head Assisted With Water Jet

Roadheader is a key equipment of roadway excavation in coal mine, the performance of cutting head of which directly determines the performance of roadheader. For safe and efficient mining of coal resources, the cutting head of roadheader should be studied and improved to increase performance of drilling and cutting. Based on this, this article focuses on research on arrangement of pick working angle and rock breaking by pick assisted with water jet. According to the results of the research, the pick’s work angle optimization cutting head assisted with water jet is designed and experimented by cutting test-bed for coal & rock.With the structure characteristics and mechanical properties of rock as the foundation, cutting breaking mechanism of rock is analyzed. Based on the actual manufacturing and installation process of pick, spatial mechanics model of pick fixed on the cutting head under drilling condition is established. Based on this, effect of working angle of pick on the force is analyzed and the formula of cutting head load under drilling condition is established.Based on the rock breaking by single pick under rectilinear condition,the accuracy of numerical simulation of rock breaking by single pick with ANSYS/LS-DYNA is verified. The process of rock breaking by pick under drilling condition is studied, and spatial mechanics model of pick fixed on the cutting head under drilling condition is revised. The results indicated that the value and slope of cutting resistance increase with elevation angle and inclination angle. The value and slope of feeding resistance increase with elevation angle, and decrease with inclination angle. Reasonable selection range of elevation angle is 0.5 times cone angle of pick tip to 50 degree and that of inclination angle is 20 to 50 degree.Based on process and mechanism of rock breaking by high pressure water jet, coupled fluid-structure equation of rock breaking by high pressure water jet is established. Flow characteristics of water jet nozzle are simulated. Simulation results show that water jet consists of the core section, rupture section and drops section, and speed of water jet on axis gradually decays. In the nozzle, the fluid medium is water. Outside of the nozzle, the fluid medium is the two-phase mixture. Closer to the nozzle axis, volume fraction of water in water jet is higher. The process of rock breaking by water jet and that of rock breaking by pick assisted with water jet are simulated. Simulation results show that stress wave on the rock generated by the water jet has a significant local effect, and pick should be be located in the stress wave when break rock. By comparison simulation of rock breaking by pick assisted with water jet, maximum force of pick is reduced by 15.77 percent and mean force of pick is reduced by 27.24 percent, which shows that rock breaking by pick assisted with water jet has a good effect.Based on research on arrangement of pick working angle and rock breaking by pick assisted with water jet, according to the current layout parameters of cutting head cutting pick, the pick’s work angle optimization cutting head assisted with water jet is designed. By experiment of rock breaking by the cutting head before and after the optimization, experiment results show that work angle optimization of pick fixed on cutting head can effectively reduce the cutting head load. Under drilling condition, the cutting torque and feeding resistance have a linear relation with water jet pressure and decrease with water jet pressure. The cutting torque and feeding resistance have a exponential relationship with rotational speed and feed rate, decrease with rotational speed, and feed rate.