Effects of cutting head motion on the boom length of rock and coal cutting machines

Cutting heads or cutting drums employing drag tools, perform the cutting action either in traversing or arcing motion. Laboratory rock cutting investigations on simulating roadheaders cutting head operating in traversing motion, showed that the pick forces were proportional to the cross-sectional areas swept by these picks. Theoretical analysis of these investigations indicated that under equivalent conditions, these areas were greater for arcing motion, and thus the pick forces became inversely proportional to the boom length. A number of in situ trials were also conducted with roadheaders of various types at OAL Mine in Turkey to evaluate the practical significance of the laboratory findings. Both the laboratory and the in situ trials indicated that within the size and the capacity of the current machines, a variation in the boom length does not significantly affect the cutting speed or the advance per revolution of the cutting head. It was however shown that if the effective boom length is around 2 m or less, together with the advance per revolution being in excess of 0.05 m, an axial type cutting head may perform better when in traversing mode. Furthermore, the concept suggesting that in arcing mode, smaller tilt angles are the case for corner cutting tools, was found to have no practical significance.