Research On Mechanical And Wear Characteristic Of Conical Pick Interacted With Coal-Rock

Conical pick is the cutting tool of mining equipment, which contacts with coal-rock directly. Its performance has direct influence on cutting efficiency of cutting mechanism on mining equipment. Thus, there will be of great theoretical significance and practical value to conduct research on mechanical and wear characteristic of conical pick interacted with coal-rock to provide basis for pick wear study of mining equipment on actual working condition of underground.According to the coal-rock cutting theory and relative motion with coal-rock of pick installed on cutting head of roadheader, wear mechanism of pick under the condition of interaction is analyzed from three aspects including wear position of pick, main wear forms and influence factors on wear. With this based on, the contact model of conical pick interacted with coal-rock is established on cutting condition, which contains coal-rock character, pick working angle, structural and motion parameters. Then, the influence of these parameters on interference between pick and coal-rock is analyzed in theory, which establishes a theoretical foundation for research on wear characteristic of pick.Based on cutting test-bed for coal-rock, cutting apparatus is developed containing plates, pick-holders and picks. Coal-rock specimens are configured according to the main imitation parameter, compressive strength of natural coal, to imitate coal-rock of hardness coefficient f=2~3. All mentioned above provide experimental foundation for the research on mechanical and wear characteristic of pick interacted with coal-rock. The cutting apparatus is used to study the influence of pick cutting types, structural and working angle parameters on pick wear, and the influence of pick wear on cutting performance is analyzed to reduce the pick wear and verify the established contact model of conical pick interacted with coal-rock.To study the mechanical characteristic of conical pick interacted with coal-rock, numerical simulation models for linear and rotary cutting of conical pick interacted with coal-rock are established using finite element method based on theories including finite element method of calculating coal-rock mass, constitutive model and erosion criterion for coal-rock and contact algorithm. Then, consistency analysis of linear and rotary models is conducted under equal and unequal cutting depth, which points out that linear model is consistent well with rotary model under those two conditions. At last, the influence of pick cutting types, structural and working angle parameters on mechanical characteristic of pick is studied by using the established numerical simulation model for linear cutting of divided pick.To study the self-rotatory performance of conical pick interacted with coal-rock, self-rotatory ability of pick is analyzed in theory. Pick rotary kinetic and resistance torque are proposed, and it points out the rotatory condition of pick in the process interacted with coal-rock. At the same time, the influence of pick-body length, pick-handle length, end face radius and pick-handle diameter on rotary resistance torque is studied. Then, the experiment study is conducted on the influence of pick cutting types, structural and working angle parameters on self-rotatory performance of pick using cutting test-bed for coal-rock. And, to reveal the mechanism of self-rotatory of pick further, the numerical model for pick interacted with pick-holder is established to study the time that pick with no rotary resistance torque in the process interacted with pick-holder on load condition. It indicates that the main factor on self-rotatory ability of pick is not friction resistance between pick and pick-holder but the time that pick with no rotary resistance torque.Experiments of coal-rock breaking by pick assisted with different configuration modes of water jet are conducted using cutting test-bed of pick assisted with water jet. The results indicate that all configuration modes of water jet have the effect on reducing pick load and wear. And the experiments establish a foundation for verifying the accuracy of numerical model. Then, the influence of water jet angle, jet diameter and jet velocity on rock breaking performance is studied based on the research of impact pressure of water jet using numerical model of rock breaking by water jet established by numerical method coupling SPH and finite element. At last, the model for conical pick interacted with coal-rock is established based on finite element method, which can represent the influence of water jet. And reducing load and wear mechanism of water jet on assisting coal-rock breaking by pick is studied according to the relation between pick load and wear. It mainly studies the influence of configuration modes, pre-splits depth and distance between pre-splits and pick tip on pick cutting force, normal wear, side wear and self-rotatory ability.