Large Diameter Rotary Drilling Rock Fragmentation Mechanism Research And Drilling Tool Design

The large diameter rotary drilling into the rock problem is a key technology in the promotion and application of rotary drilling rig, the contradiction between the large work surface with limited input capability is the essence of rotary drilling into the rock problem. The solution to this problem lies in the theoretical study of the rock crushing.Theory of rock fragmentation under static and dynamic loads are analyzed based on the movement under combined loading rock crushing theory movement under combined loading broken rock mechanical model:the rock crushing process is divided into elastomer-damage body-the fracture body three stages, application of elastic mechanics, damage mechanics, fracture mechanics and rock mechanics analysis,"Axial Compression rock pre-injury" and "complex static and dynamic load the next rock damage evolution model" two-point theory.The significance of the model are as follows:(1) model derived from the static pressure and dynamic load (impact) source rock cracks, the relationship between the degree of damage and the crack length.(2) model of rock damage under concentrated force maximum shear stress of the elastic half-space trajectory (two logarithmic spiral) as rock damage evolution path, type Ⅰ (open type) and Type Ⅱ cracks (slip-on type) as the movable set out under the impact pressure shear crack propagation mode, crack propagation final result is the formation of macro-dense core with the intermediate radial and lateral crack.(3) The model can be broken rock drilling tool design parameters (static pressure, impact energy, impact frequency and distribution of the teeth pitch) is instructive.Using virtual crack (VCCT), finite element software ANSYS14.0movement under combined loading rock of crack propagation simulation, comparative analysis of15of crack propagation under different load conditions, the analysis shows:rock movement under combined loading crack propagation speed is higher than the simple static load or dynamic load, increase static pressure or impact are conducive to increasing the length of the crack propagation, in particular to improve the dynamic loading; reasonable selection of static and dynamic load ratio can be achieved the optimal crack propagation results.On the basis of the above analysis, with reference to the design of the traditional Rotary Drill, we designed a set of rotary drilling into rock drilling tools-built-in shock double cone twin screw auger short cone:(1) the use of the pitch helix dog the volume of the rock breaking principle spatial distribution of the teeth programs, the cutter layout program have advantages in terms of load distribution, tool wear.(2) to design the various components of the spiral drill:side cover, spiral blades and center drill, and design a key power transmission parts to strengthen measures.(3) The investigation and analysis models and performance parameters of the pneumatic impact at home and abroad, the selection of Air Impact program.(4) analyzes and summarizes the process parameters of the big bore-rotating into the rock process.