Design Of Hand-held Mining-drilling Machine With Static Hydraulic Balancing

The hand-held mining-drilling machine was used in underground coal mine and other surroundings where existing massive explosive mixed gas such as methane and coal dust.So from the view of safety,there are potential safety hazard in the use of electric coal drill.Wind coal drill has small drilling capacity and large volume,in In practical working,it may produce poor conditions with high noise and much dust,making it difficult for the manual operation.To solve the above problems,in this paper we designed a new type of hand-held mining-drilling machine.This equipment uses the hydrostatic balance motor as the power source,uses the planetary gear train to increase the rotational speed and take advantage of the bit's cutting performance to carry on the coal rock drilling.The main structure design and dimension calculation of the mining-drilling machine was showed in this paper,also,we designed the hydraulic circuit design and maked reasonable arrangement of the motor and planetary gear train.In particular to include the design and calculation of the main parameters on the motor parts,the selection of the number of teeth and displacement coefficient of the planetary gear,and the check of the contact fatigue strength and bending fatigue strength of gear.Especially for the hydrostatic balance motor,we maked analysis of force and movement of its some important parts as well as the calculation and analysis on flow characteristics of the motor.For the crankshaft,the force analysis and the strength check was conducted when the initial angle of the crankshaft is of 0°,because that the crankshaft was mostly suffered from cyclic bending moment,so the strength check refers to the fatigue strength.Then,the displacement,velocity and acceleration of the piston were analyzed,and the mechanical efficiency of the whole mining-drilling machine was calculated.For the hydraulic circuit,using the flow relationship and compressible fluid continuity equation to derive mathematical relationship of the flow,while establishing mathematic relation of the drill output based on the torque balance.Then,the transfer function of the hydraulic loop and drill torque were solved by the use of the Laplace transform.Further,we establish the simulation model with the help of the Simulink module in Matlab,and study the torque characteristics of the hydrostatic balance motor.Finally,the modal analysis of the crankshaft was completed to study on the low order natural frequency and vibration mode of the crankshaft after using SolidWorks to build 3D model of drilling machine and meshing the crankshaft parts in the workbench module of Ansys.So as to prevent the fatigue failure caused by the resonance of the crankshaft of the hydraulic motor.