V. Khilov1 & S. Kobylanskyi1
Solution of the actual scientific and applied problem of the modern quick-acting drive systems frequency characteristics dynamic compatibility with the drilling rigs dynamic characteristic.
Experimental study of the DC drive armature current, AC drive stator current, rotational speed, power consumption, vibration displacement of the pressure swivel head crosspiece and harmonic analysis of transient graphs in the start and start drilling modes.
Analyzing the experimental data obtained in the mining and geological conditions of mining and processing plants, the following generalizations one can be made: 1. Increase in the speed of the bit rotation leads to increase in the frequency and amplitude of the drill rod oscillations; 2. Axial pressure on the drill rod practically does not affect the values of the frequencies of forced vibrations; 3. With increase in drilling depth, the vibration amplitudes increase due to a decrease in the rigidity of the transmission (since with an increase in the depth of the well, the operating rotation frequencies become lower).
In the drilling rig SBShS-250N in the with an AC transistor drive has appeared new regularity: with an increase in the rotational speed of the drill bit, the unacceptable oscillation amplitudes of the drill rod are appear at frequencies lower than in the SBSh-250MN-32 drilling rig with a DC drive.
Factors causing vibration of the drill string during rock destruction can be divided into two classes: 1. External disturbances arising from the interaction of the roller cutter with the face and the impact of the rod during drilling on the inner surface of the well; 2. Internal disturbances arising from the natural vibrations of the drill rods.
In the amplitude-frequency characteristics spectra of the SBShS-250N drill rig vibration a harmonic appears at the frequency = 15.92 Hz, which does not depend on the rotation frequency . The remaining harmonic components obey the same laws as for the SBSh-250MN-32 drilling rig. The appearance of harmonics of oscillations of the drill string, which are independent of its rotation frequency, indicates the manifestation of the internal dynamics of the drill string in the drilling process. Thus, in the SBShS-250N drilling rigs, when developing drive systems, it is necessary to take into account the natural vibration frequencies of the drill string.
At a rotation frequency of 120 rpm, there has been the approach of intrinsic and forced oscillations of the drill string is approaching, that is, the latter operates in a mode close to mechanical resonance, which negatively affects the durability of the nodes and the drilling rig as a whole.
The report is contained the researchers, which were conducted within the project 0108U000557 , financed by Ministry of Education and Science of Ukraine.
Keywords: DC drive, AC drive, drilling rig, harmonic analysis.