Investigations into tilt angles and order of cutting sequences for cutting head design of roadheaders

This paper explains optimum arrangement of gauge tools and corner cutting picks for cutting head design of roadheaders. Full-scale simulation of roadheaders cutting heads of practical types with a wide range of tilt angles was carried out through laboratory linear cutting experiments. The trials showed that optimum tilt angle for corner cutting picks was approximately equal to the half breakout angle of the rock, and corner cutting picks acted as gauge tools after this value. Tilt angles greater than the optimum value were not recommended for both gauge and corner cutting picks, due to poor cutting efficiency and tool holder problems. Higher specific energy was found when the order of cutting sequences of unparalleled axis tools (the gauge tools) was arranged to start cutting from nose side of the cutting head than that of the opposite direction. The parallel axis tools on roadheaders cutting heads were, however, understood to be not affected by the order of cutting sequences. Furthermore, the effective area method which was previously suggested for tool force calculation of parallel axis tools was also verified for unparalleled axis tools investigated in this research study.