Condition Monitoring Applications of Crushing Plants
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Effective use of machinery and maintenance planning requires improving of situational awareness and knowing the condition of the machinery. In mineral and aggregate industry, the maintenance is traditionally performed according to fixed time intervals or when the machines break down. One implemented solution for improving situational awareness is different kind of remote monitoring solutions. Knowing the condition of the machines improves the up-time and helps to prevent unexpected failures of the machines that work in difficult conditions. There are various condition monitoring products and services on the market, but they may not fulfil directly all of the requirements of this industry. It may therefore be a risk that the condition monitoring may not be comprehensive enough, if they are implemented with those commercial services. The goal of this work is divided in three research questions. The focus of the work is on the first one. The question number one is associated with searching of condition monitoring applications, which are application specific for mineral and aggregate industry. In this context, this work reviews different condition monitoring methods, but the actual measurements are implemented by using vibration sensors. The found application specific condition monitoring methods are tested by designing and implementing measurement setup. The measurement setup is installed on a mobile crushing unit – Metso Lokotrack LT106. The measurement setup includes measuring of machine orientation, monitoring of a frame bearing of the crusher and monitoring vibration of machine’s main conveyor. The used data-analysis methods are calculating the machine frame orientation by using the measured direction of gravity, monitoring of vibration root-mean-square velocity, envelope analysis of bearing high-frequency vibration and analysis of vibration frequency spectrum. The second research question estimates the minimum hardware requirements for the measurements, so that the desired phenomena can be reliably detected. The third question is to assess the economic feasibility of the selected measurements. Based on the results of this work, the current single point measurement of unit orientation is insufficient solution. Elastic frame may twist too much during use of the machine, and the operator may not notice it. On the other hand, inclination of the machine may change excessively during the use, if the ground under the machine sinks. In case of the crusher frame bearing, the result of envelope analysis indicates developing faults in a rolling element and inner race of the bearing. In turn, monitoring of the vibration root-mean-square velocity of the main conveyor does detect excessive vibration during the monitoring period, which is quite expected result, because the conveyor is accurately designed by using Finite element method. Based on the results, the orientation of the machine would be worthwhile to implement as commercial product, as well as the crusher bearing condition monitoring.