Search

The tensile properties of conveyor belts significantly affect their use in practice. Research is focused on the determination of the influence of sampling direction on the tensile strength and the elongation of 3 types of fabric conveyor belts. The carcass material determines the tensile properties of the conveyor belt. The carcass of a fabric conveyor belt is formed by several layers of textile plies. The textile plies are created by crossing the system of warp and weft fibres. The warp represents a set of fibres in the longitudinal direction and the weft of fibres in the transverse direction. Such textile structure is directly responsible for the tensile properties of the belt itself. Even a combination of different warp and weft textiles is used to achieve better properties. The usage of polyester (E) fibres in the warp and polyamide (P) fibres in the transverse weft was applied in the investigated EP type of belts. This construction is characterized by good resistance to dynamic fatigue and it protects the belt from the formation and propagation of breakdowns. The aim of the work is the experimental research of conveyor belts of different tensile strengths used in mining. [ABSTRACT FROM AUTHOR]

Application of rubber at higher temperatures requires sufficient heat resistance. The experimental research was carried out with the rubber intended for use at higher operating temperatures as gaskets for caps in mining. The intakes during the operation of the rubber gasket are accompanied with physical as well as chemical changes that lead to thermal degradation of the material. The mechanical properties (tensile strength, elongation, Shore hardness, and abrasion resistance) of the examined type of rubber were determined for unused, i.e., new rubber. The rubber samples were subjected to accelerated thermal ageing at 180 °C for 3 days. After ageing, the mechanical properties of the thermally degraded rubber were determined in order to establish its heat resistance. Strength and elongation decreased by ageing, but the Shore hardness increased. The percentage of change in the strength was -1.2 %; -8.9 % for elongation; and the absolute change in the Shore hardness was 1.7, representing a 2.3 % increase. Thus, the heat resistance of the tested rubber was sufficient, as confirmed by the measured mechanical properties (strength, elongation, and Shore hardness). [ABSTRACT FROM AUTHOR]

Transport and environment rank among current global problems as the transport and the environment are closely interconnected. The environmental impact of all types of transport is manifested in various forms, such as noise, environmental pollution by harmful substances, soil demand, etc. These issues are rather complex, and the solution thereof is even more complicated. The current situation in the transport of materials is characterised by increased performance of means of transport and the reduction of their negative effects on the environment. That is why the current efforts are primarily focused on the development of enclosed conveyance systems which not only show good technical parameters and require low costs, but also meet the third requirement, i.e., being environment-friendly. The present article deals with newly developed enclosed conveyance systems. It describes the principle of their operation and particular operational applications in the mining industry and mining operations (digging tunnels). The article describes their function mechanism, basic structural components, advantages, disadvantages and the application of the enclosed conveyance systems Sicon, U-Con, Ecotubelt and others in the mining industry. Due to simple assembly, significant reduction of maintenance costs, high transportation capacity, and improved working environment, they are predetermined for a wide range of applications. Enclosed conveyance systems are multipurpose systems of the future, suitable for the conveyance of materials. They share many advantages, such as cleanness, safety, adaptability to multiple loading methods and various situations, independence from weather conditions, extremely high productivity, absence of environmental pollution by transported materials, elimination of noise and vibrations, smooth negotiation of inclines, declines and track curves, and the ability to convey materials over long-distances - from several kilometres to several hundreds of kilometres. The greatest advantage of such systems is their ecological cleanness which contributes to the improvement in working conditions, especially for the system operating personnel; it also improves and protects the environment within a large surrounding area. At present, a large number of tunnels are being built all over the world, most intensively so in Asian countries, such as India, China and Hong Kong, where dozens of tunnels are currently being built. Construction of tunnels in the Slovak Republic is affected by great difficulties regarding the selection of technology and technological procedures for removal of material, as a result of complex geological conditions and short lengths of the dug sections. Construction of each tunnel is specific and, accordingly, so is the selection of technological procedures for the removal of disintegrated soil. The article describes the function mechanism, applications and operation of enclosed capsule conveyance systems suitable not only for the transport of disintegrated rock from the tunnel, but also for the transport of mineral materials in the mining industry. The final section of the article presents the comparison of alternative applications of enclosed conveyance systems, applying the evaluation criteria, and the resulting order of individual alternatives based on the expert approach, using the methods of decision - making analysis. [ABSTRACT FROM AUTHOR]

The accelerated ageing affects the quality of an important element of the belt conveyance.-a conveyor belt. This paper analyses the resistance of the belt cover layers to the deterioration caused particularly by the accelerated ageing. The investigation was carried out using the fabric conveyor belts of the P 2000/4 type (4-layer textile belts with a polyamide carcass, the strength of 2,000 N/mm) at different ageing periods. The effect of ageing on the rubber cover layers was identified on the basis of the observed hardness values. The type of the conveyor belt that was more resistant to ageing was identified by analysing the measured data. The basic methods of thermal ageing, including the analysis of the selected methodology, are presented herein. The hardness of each type of rubber increased due to the ageing and the ageing period also played an important role. The samples exposed to the 3-day ageing at 100 °C showed 2.5.-3.5% higher hardness values. For the samples exposed to accelerated ageing for 7 days, 4.-5.3% higher values were observed. These results show that the hardness depends on the ageing period. [ABSTRACT FROM AUTHOR]