Justification of the parameters of rotary-vibration drilling of small-diameter boreholes in rocks based on a submersible cavitation hydrovibrator

Abstract

The article presents the results of laboratory studies of the rotary-vibration drilling method of blast-holes and boreholes of small diameter based on a submersible cavitation hydro-vibrator. A generator that operates in the mode of intermittently stalled cavitation was used as a source of vibration load to the rock-breaking tool. The authors of this article developed and described the design of a submersible cavitation hydro-vibrator at the level of the patent of Ukraine for the invention. In addition, a bench design for laboratory studies of the parameters of a rotary-vibration drilling method was developed and described at the level of a patent of Ukraine for a utility model. It is established that the optimal mode of operation of the cavitation generator is ensured by its cavitation parameter in the range of 0.16-0.2. The geometrical parameters of the cavitation generator in the submersible cavitation hydro-vibrator are determined: the diameter of the critical section is 2.0 mm, the opening angle of the diffuser is 20º, and the outlet diameter is 10.0 mm, and the length of the post-diffuser channel is 200 mm. It is established that under the action of pressure pulses of the washing liquid, which is passed through the cavitation vibrator in the optimal mode, the additional deepening of the rock-breaking tool into the rock sample reaches up to 0.6 mm per rotation. Thus, the drilling speed of small-diameter blast-holes and boreholes (up to 55 mm) with the ЕБГП‑1М drilling rig of the Konotop Machine-Building Plant with the optimal mode of the rotation frequency of the rock-breaking tool, which equals 315 min-1 (5.25 s-1), can be increased by 3∙10-3 m/s, from 23∙10-3 m/s up to 26∙10-3 m/s, which is 13%. Keywords: the rotary-vibration drilling method, cavitation generator, submersible cavitation hydro-vibrator, mining rock.