Significance of cutting process parameters as related to improving dynamic state of roadheader and minimizing power consumption

Abstract

The process of mechanical excavation, especially that of hard rocks, is very dynamic. This results in heavy loads and vibrations in the cutting system of a roadheader, the drive units of the mechanism related to the excavation process, and the load-carrying structure of the roadheader. The ad verse dynamic state that stems from excessive dynamic loads or even overloading will cause a high failure rate in the roadheader and low efficiency of its operational process (high energy consumption, low productivity), thus leading to high costs of driving tunnels using the mining method involving roadheaders. This article presents selected results of extensive computer studies on the impact of cutting process conditions on the dynamic state of a boom-type roadheader equipped with transverse cutting heads and on the energy consumed during the excavation process. On one hand, cutting process conditions result from properties of an excavated rock material and, on the other hand, from process parameter values set up during the excavation of tunnels. Simulation studies conducted using experimentally verified mathematical models made it possible to identify relationhips that link dynamic loads of the body of a boom-type roadheader and energy needed for mining to the cutting process parameters of rocks with different compressive strengths. The regulation properties obtained in this way show the possibility of reducing dynamic loads of the roadheader through the proper control of cutting process parameters, including the angular speed of the cutting heads. By equipping the roadheader with a cutting head inverter drive system, it is possible to adjust the speed to the cutting process conditions by changing the supply voltage frequency of an asynchronous motor installed in the roadheader's cutting system.