The Analysis And Simulation Of DTH Drill Propulsion And Rotary System

Propulsion systemand rotary system are two most important systems of down-the-hole drill. Down-the-hole drill can only operate fast and effectively with the cooperation of propulsion system and rotary system. The existing down-the-hole drill divides propulsion and rotation as two independent systems without interference. In order to avoid sticking, some down-the-hole drills gather the signal and control the propulsion system to change to promotion from propulsion when rotary pressure goes up to a certain level. This paper proposes the scheme that uses rotary system to control propulsion system according to the cooperation of propulsion system and rotary system, and the proposal has been verified with simulation.This paper firstly makes a brief introduction to the historical development and manufacturers of down-the-hole drill both at home and broad. Then, it analyzes the the features in propulsion mode of existing down-the-hole drill. The previous propulsion mode has shortcomings, so this paper puts forward that the rotary pressure of operating rotary system and the changing rate of rotary pressure can be used to control the input current in pilot-operated type proportional decompression valve, so as to change the level of propulsion pressure. It takes fuzzy control as the controlling mode, and the rules of fuzzy control have been verified.This paper establishes the simulation model of propulsion and rotary systems according to AMESim Hydraulic Simulation Software, and has verified the correctness of model establishment. It relies on the fuzzy controller in MATLAB to establish the fuzzy controller. The author uses the Simulink Software to establish the controlling model of propulsion and rotary systems and the joint simulation of AMESim/Simulink has been realized. The paper also verifies the feasibility of using propulsionsystem to control rotary system. Besides, the cooperation of propulsion system and rotary system can avoid bit wears because of high level of rotary pressure when down-the-hole drill operates. When rotary pressure is low, the propulsion pressure can be built up, so that the productivity can be raised.