Impact Rock Breaking Signal Processing And Drill Resistance Characteristics Inversion Identification

The mutual mechanism between drill bit and rocks is reflected by the force-penetration relationship curves and is the basement on which the diagnosis to working status to be done and on which the optimistic control to be achieved in the percussive drilling mechanical system. It is difficult to measure the force-penetration relationship curves directly, but to get the force-penetration relationship of drill bit and the rocks must know the characteristic impedance of drill bit in indirect test method. The characteristic impedance at the cross-section of a uniform rod can be easy to obtain,but the drill bit having a complex geometry and non-uniform is hard to exact calculation. And the connection status of drill rod and drill bit also affect the variable characteristics impedance. So it is valuable both in theory and practice to engage in finding ways to calculate the characteristic impedance of drill bit.This paper presents an inversion identification method that can accurately calculate the characteristic impedance of drill bit by theoretical analysis, numerical simulation and experimental research. Based on percussive drilling dynamics, one-dimensional wave dynamics and information processing, pays a great attention on the wave characteristic impedance of rod in a binary percussive system. And the paper contains the following works:(1) According to the diversity of wave mechanics numerical analysis method, the author analyzes the propagation of stress waves in the variable cross-section elastic rod. Two methods of calculating the characteristic impedance of drill bit are proposed and compared, one is based on incident and reflected waves at one point and another is based on the characteristic lines and two points'strain test.(2) A horizontal impact text platform is built and a series of methods of signal processing are presented based on the characters of impact signal which only keeps for a short time but changes swiftly, and characters of the test signal which contains a lot of noise signals. Besides, according to the characters of waveforms and stress wave transmission, the method of how to determine the starting position of incident and reflected waves was discussed.(3) Three different shapes'drill bits are identified according to the analysis of two inversion methods. The identification results and the source of error are analyzed and discussed as well. These studies verify that the two invertion methods are effective and feasible. It is found that these methods can accurately calculate the characters of impedance drill bit with a complex geometry, which is also beneficial to optimizing drill tools design in percussive drilling.