Performance Analysis And Optimum Design Of Work Device Of Rotary Drill

Rotary drill is a kind of drilling machine shattering rocks by cutting drill bit, also known as rotary cutting drilling machine. Rotary drill has been used in mining engineering for many years, but most used as drilling machine applied to underground coal mine with relatively small hole diameter, such as electric drill used in coal mine. Along with the large-scale exploitation for coal resources at home and abroad, the use range of rotary drill expands gradually. The drilling rig referred in this paper is used in boring construction of strip coal mine prior to blasting; the target depth for borehole is 12m, and rated hole diameter is 120mm. When drilling, axial pressure is exerted onto bladed bit through slewing gear and pressurized structure, and the drill bit intrudes into the coal under axial pressure and shatters coal under the function of rotary torque. The drilling rig discharges fragments by helical blade; the spiral drill pipe rotates in the borehole and forms a screw conveyor with the borehole wall. Under the drag forces of centrifugal force and friction, etc., the coal fragments at bottom hole are conveyed upward through helical lobe on the helical blade, and the drilling tool moves downward to finally complete drilling progress. In the designing and running of rotary drill,how to correctly select structural parameter to obtain the best working efficiency still remains an important topic which should be further reseached.The drilling efficiency of rotary drill is affected highly by the conveying capacity of helical blade and absorbing load capacity of drill rod. The conveying capacity of drill pipe is relevant to the structural parameter of the blade on the helical blade, and the absorbing load capacity of drill rod is based on the outside and inside diameters of drill rod axe and the thickness of helical blade. In order to improve the drilling efficiency of drilling rig, in this paper, on the basis of theoretical deduction of conveying capacity and the optimization target of the largest conveying volume of helical blade, the blade pitch, rotary speed and axial diameter of drill rod are obtained, and then the optimal drilling speed is achieved; Afterward, a drilling system model of drill bit is established by using ABAQUS finite element analysis software, and the power required for working head of drilling rig in the conditions of structure of existing drill bit and optimal drilling speed is simulated by nonlinearity contact analysis;finally, we have analyzed the effects of helical blade and inside diameter of drill rod axe on the quality of drill rod and stress in the static condition by adopting DOE technology specified in ANSYS WORKBENCH DesignXplorer module, form auger rod modal neutral file containing stress strain information by synthetically applying PRO/E and ANSYS, set up rigid-flexible body model of drilling system in the introduced MSC.ADAMS, simulate the drilling progress of auger rod, extract related data information from the ADAMS post processing module, acquire the drilling track of drill rod and contact state of hole wall, and take an analysis on the deformation of drill rod.In this paper, the analytical study and optimization on working performances and structural parameters of work device will play an important guiding role and bring the significant application value to the improvement of drilling rig and drilling efficiency.