Regime and rock identification in disintegration by drilling based on vibration signal differentiation

Abstract

On the basis of analyses of the vibration signal monitored during the drilling into tested rocks on the laboratory drill stand using a diamond impregnated drill bit, it is possible to state that in constant drilling conditions a disintegration regime and a disintegrated rock exhibited certain specific vibration patterns in the time, frequency, and time-frequency domains. A change of the applied regime or the used rock was sufficiently differentiated in the values of the vibration acceleration in the direction of the drilling axis. During the disintegration of fine-grained rocks (andesite and limestone), peak acceleration amplitudes increased with an increasing drill bit rotation speed. Materials with larger grains (granite) exhibited increased amplitude components in the frequency domain, at low rotation speeds, in the vibration spectrum of the signal. In the created spectrograms, different grain sizes of the tested materials were reflected in different intensities of peak acceleration amplitudes and the respective dominant frequencies. In andesite, limestone and granite, in the area of the rock disintegration by chipping, the polynomial correlation between the drilling rate and the vibration signal was identified while the vibration signal was processed in the frequency domain, depending on the changing drilling conditions and parameters.