Fundamental Study on Vibration of Roadheader

Abstract

Pick failure is often induced by severe vibration of cutting drum when the roadheader is trying to cut the rock of high strength. This would have two consequences. First, the direct cost of picks is increased.Second, the time lost in changing picks may become a significant portion of the overall downtime. For this reason, the analysis ofvibration of roadheader is an important problem to apply the roadheader to the rock of high strength. However, neither the force induced by cutting nor the model of roadheader to analyze the vibration are known mainly because of the complexity.
In this study, first, the force induced by the cutting is examined with the aidof newly developed computer program. The calculated results are shown in Table 1, which indicate that on cutting of highstrength rock, the dominant frequencies of induced force are 12.5, 0.83 and 11-23 H_zdepending on the causes.
The simplified vibrational model of roadheader to analyze the mode and natural frequency is proposed. The calculated results with the computer program developed for this study indicate that the resonance may occur with the primary or secondary mode of the estimated natural frequency of 5-8, 10-15 Hz respectively. Also, the torsional vibration of shaft-gear system from the cutting drum to the electric motor are examined by the transfer matrix method and foundthat the vibration of the shaft-gear system may not be severe problem.