Online monitoring of a pipe conveyor. Part I: Measurement and analysis of selected operational parameters Vieroslav Molnár a,⇑ , Gabriel Fedorko a , Miriam Andrejiová b , Anna Grinc ˇová c , Peter Michalik d a Technical University of Kosice, Park Komenskeho 14, 042 00 Kosice, Slovak Republic b Faculty of Mechanical Engineering, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovak Republic c Faculty of Electrical Engineering and Informatics, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovak Republic d Faculty of Manufacturing Technologies of Technical University in Kosice with a seat in Presov, Bayerova 1, 080 01 Presov, Slovak Republic article info Article history: Received 23 July 2016 Received in revised form 12 August 2016 Accepted 13 August 2016 Available online 13 August 2016 Keywords: Contact force Rubber-textile conveyor belt Idler roll Regression models Pipe conveyor abstract The need to maximize the performance and operational reliability of ecological continuous conveyor sys- tems is increasing nowadays and their requirements are difficult to fulfil. One of the main reasons to this is the complexity of ecological continuous conveyor systems. Regular tracking and monitoring of systems selected parameters and indicators support their proper functioning and operational reliability. However, the process becomes useless if the parameters are not tracked and evaluated. The paper shall present the results of research aimed at determination of evaluation criteria for selected parameters. The research was carried out by a method of experimental measurement on an experimental rig the construction of which is similar to the construction of real pipe conveyors used in practice. Some of the convenient parameters to be tracked on a tube conveyor are a tension force and contact forces on hexagonal idler housing. The paper aims to track the course of contact forces and their mutual relations with intensity of tension forces. In order to create a comprehensive evaluation and analysis of the research, the exper- imental measurements were carried out for two cases, with and without material. The experimental tests are evaluated with the use of basic mathematical and statistics methods. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Conveyor units represent a very important part within majority of logistic systems. Their role is to transport variety of materials and foster the functioning of individual technological processes. Their reliable operation, maintenance and execution of decision- making processes depend on operational parameters monitoring as well as their evaluation [1]. Due to this, various reports and reviews can be produced [2] or the operation can be controlled based on the obtained parameters [3]. The kind and extent of the tracked parameters depend on many factors. Every conveyor system has its specifications and require- ments. The most complicated conveyor systems, with regard to tracked parameters, are the ones that contain conveyor belts. Monitoring of conveyor belts’ operation is the key condition for their effective and reliable functioning [4]. Because of this, the issue has been much researched along with the development in various fields of technologies suitable for monitoring purposes. The research of monitoring and controlling system for conveyor belts was conducted by Wang et al. [5]. They came to a conclusion that monitoring and controlling system can significantly con- tribute to reduction of physical work and reduction of number of accidents. The importance of conveyor belts monitoring is also supported by its necessity in various fields of industry. One of them is the mining industry where conveyors play an important role. The research of monitoring system for conveyor belts in coal mines had been carried out by Wang and Zhigang [6]. The main idea of the designed system is based on the monitoring of the drive unit operation. The other research on monitoring system design of conveyors in coal mines can be found in [7]. Designed and above mentioned monitoring systems allow tracking of a single or several parameters. One of these are the parameters of material handling as presented in his work by Li et al. [8]. One of the options of tracking the operation of conveyor belts is presented by Pang and Lodewijks [9]. They suggest the application of RFID technology and its implementation in supporting rollers. The other possible way of operational conditions monitoring is suggested by Min [10]. In his work, developing of security system for conveyor belt using the steel-cord type of conveyor is being described. Lee and Au [11] proposed a new conveyor system called http://dx.doi.org/10.1016/j.measurement.2016.08.018 0263-2241/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: vieroslav.molnar@tuke.sk (V. Molnár). Measurement 94 (2016) 364–371 Contents lists available at ScienceDirect Measurement journal homepage: www.elsevier.com/locate/measurement