The effect of cutting head shapes on roadheader stability

Amongst mechanised excavation equipment, roadheaders have an exceptional role. Determination of the stability state of the roadheader is an important parameter for the efficiency of excavation. For roadheaders having equal power and weight, if one is more stable than another, it can respond to higher boom forces. A new computer program was developed to analyse the stability of roadheaders. Values of the four stability states of the roadheader (turning around the vertical axis, turning to the side, turning backwards and sliding) can be obtained using this program. In this study, the effects of the cutting-head shape (spherical, conical and combined heads) were investigated by applying this method to the stability of a longitudinal type roadheader. Turning around the vertical axis of the machine was found to be the most critical stability state. Among the different cutting head shapes, spherical heads had the lowest moment values for similar tilt angles. An increase in the tilt angles of the picks leads to an increase in the moment values for all cutting shapes with this stability state. However, small tilt angles of the picks are commonly used due to their high efficiency. The increase in the tilt angles of the picks negatively affects the sliding state of the roadheader for all cutting shapes, especially conical heads. The stability states of the roadheader in turning backwards and turning to the side were slightly affected by changes to the tilt angles of the picks. The results obtained are valid for all cutting sector; however, a 90 degrees cutting sector was more convenient than a 180 degrees cutting sector due to lower boom reaction forces.