Power characteristics of néti-1-BM electromechanical hammer drill

Abstract

1. The proposed electromechanical hammer drill stores energy in its hammer head during the forward and return travel of its slide, thus ensuring uniform loading of the motor; the impact energy can be varied by the use of springs of various stiffnesses; and there is constant impact energy and unvarying internal working of the hammer when the feed pressure changes. 2. Rock-breaking by percussive-rotary drilling is due not only to the blows of the bit, but also to its rotation. 3. The relative distribution of power between the units shows that the power expenditure in the drive mechanism is great and constitutes 20–40% of the over-all energy consumption for various drilling conditions. It can be reduced by dispensing with the reduction gear. 4. For a given machine, the energy of a single blow has little effect on the relative power distribution between the individual units (5–10%). 5. For any given rock, there is an optimum impact frequency at which the efficiencies of the hammer and drive units and the over-all efficiency are at a maximum. Percussive-rotary hammer drills intended for drilling different types of rock should have an adjustable impact frequency, so as to obtain minimum energy expenditure and high efficiency.