College of Mining, NUST MISIS, Moscow, Russia:

E. E. Sheshko, Professor, Candidate of Engineering Sciences, esheshko@mail.ru

Navoi State Mining University, Navoi, Uzbekistan:
L. N. Atakulov, Associate Professor, Candidate of Engineering Sciences

Recently, there are a number of alternative designs for pressure belt steep-angle conveyors: these are blocks of pressure elements and flat to high-angle transition loading sections. The transition section is less elaborated while the pressure and loading paths in this section are subjected to tensile and flexural forces capable to cause compression of the belt layers, instability and shape loss of the belt, its folding, rupture and drop in the service life. The engineering solutions exist for small rubber belt conveyor are known, yet the investigations for the modern sandwich belt high-capacity high-angle conveyors are to be carried out. Considering that belts are orthotropic and belts of the same strength and longitudinal elasticity modulus can have different transverse moduli while belts in the transition section are bent both lengthwise and edgewise, the theoretical justification of the radius for this section requires assumptions which distort the pattern of forces, stresses and strains affecting the belts. For this reason, the stresses in the belts in the transition section of a steep-angle conveyor are analyzed in ANSYS environment. Modeling of St-5400 steel cord rubber conveyor belt included loads calculated for the high-angle conveyor in the Muruntau open pit mine of Navoi Mining and Metallurgy Combinat, Republic of Uzbekistan (conveyor capacity Q = 3500 t/h, angle β = 37°, height Н = 270 m). In the belt–load–belt system assumed as an elastic beam (to avoid over-stress of the both belts), the radius of the load-bearing belt (limit value) is planned as 1679 mm, which is difficult to implement. Modeling of this system shows that some fibers of the belt are compressed even at this radius. One of the methods to reduce the transition section radius is the increase in tension and, thus, belt (given sufficient strength). This is the only way out for some conveyors. In the discussed type of conveyors, the transition section layout allows the other approaches to the radius reduction: increase in the pressure on the pressure belt, variation in the spacing of carrying rollers in the transition section, and combination of these approaches. According to the research, the highest effect is achieved with the increase in the belt tension in combination with the build-up of the pressure force and reduction in the spacing of carrying rollers. The modeling results show that varying parameters of a steep-angle conveyor with pressure belt allows reduction in the transition section radius without overstress or folding of the belt but with preservation of its shape and motion stability. It is supposed that operating cost of the belt will lower in this case while the life time will extend.

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