Abstract
Since a drill must have enough power to crush various rocks, it is necessary for analysis of the dynamic characteristics of a pneumatic rock-drill to consider the physical property of rock under drilling. Thus, the effect of the property of rock the dynamic charactristics of the drill was examined experimentally by using four kinds of rocks. The following results were obtained.
(1) Although the blow velocity and the air consumption are not affected by the property of rock, the number of blow is greatly affected and increased with increasing Shore-hardness of rock. This fact indicated that Shore-hardness of rock must considered as a factor affecting the dynamic characteristics of the drill.
(2) Considering the fact that the net thermal efficiency increases with increasing performance-index under drilling, it is confirmed that the previous criterion presented by one of the authors can be applied for the design of a pneumatic rock-drill.
