Accurate quantitative evaluation of the performance of pneumatic rock drills is important to improve the performance and put the design on a scientific basis.
A rock drill receives energy from a compressor or a hydraulic system and transfers impact energy through the drill and bit to crush rocks. Impact energy, the main performance index of rock drills, was estimated by many researchers in an indirect way because direct measurement is difficult.
Those measurement methods are difficult to apply to the performance tests of mass-produced drills as they require modification of the structure of percussion drills or preparation of standardized rock samples.
In view of these practical requirements, Pak Chol Hyok, a researcher at the Faculty of Mining Engineering, proposed a new structure of impact energy measurement device and analyzed its performance through simulation.
The analysis results show that the stress wave transmitted through the drill rod is converted into the pressure wave of oil filled inside the cylinder. Its maximum value is 15-28MPa, varying with position. Therefore, suitable location of measurement points can raise measurement accuracy while extending the service life of the sensor.
The newly proposed measuring device is more reliable and more convenient to operate than the method of determining the impact energy by stress wave measurement.