Abstract:

Rotary bit drilling rigs play an important role for blast - hole drilling in several open - pit mining fields at Quang Ninh, Vietnam. It is evident that the stability of hydraulic cylinders and rock resistance essentially influence on effective drilling - stroke length. At a certain hard rock the length of effective drilling - stroke could be expanded. It is considerably greater than fixed stroke. This paper presents the calcualtion method to determine the effective drilling - stroke of rotary bit drilling rigs CBW - 250 MH which are used to drill blast - hole at Cao Son coal mine and Coc Sau coal mine. As the obtained result, the machine productivity is grown up approximately a half by adding 2 more travelling ropes