'ev UDC 622.64 Vibrator belts -simple, reliable, compact devices for discharge of loose loads from bunkers, etc. -are becoming increasingly popular. There are at present about 200 vibrawr belts operating in nonferrous-metal mines. They are used for discharge of ore from blocks [1]. The throughput of the working specimens of vibrator belts is 200-500 wns/h. If necessary this can be raised by a factor of 2-3 by increasing the dimensions and mowr power.The use of vibrator belts in the coal industry shows very great promise -for bunkers in pits, in dumps, for discharge of coal from the face area, for its transportation along workings sloping at 0-35 ~ , etc. In this connection, at the Institute of Mining, Siberian Branch, Academy of Sciences of the USSR,we have carried out extensive investigations in which special attention was paid to experimental determination of the basic parameters of the vibrations (in particular, their damping), their wavelength, and its variation atong the belt as they are damped. A knowledge of these parameters is necessary for calculating the velocity of material along a vibrator belt, and for choosing its length and the sites of the drive units, etc.We used a specially constructed full-scale test rig (Fig. 1). In a concrete foundation we laid a rigid welded frame 1, a base 3 on which we mounted eccentric vibrator 2, and a slab supporting mowr 5. The vibrator is connected by Cardan shaft 4 with the mowr, and via a rocker with the vibrator belt 7 lying on the transverse beams 6 of the frame. The right-hand end of the belt is fixed to the frame.We made tests under idling and load conditions. In the latter case a side flange was fixed to the frame. We tested belts 5000 mm long, 200-1200 mm wide, and 5-10 mm thick with motor rotation ratesoflO00and 1500 rpm and vibrator amplitudes of 3.6 ram. Under load, the load was 570 kg or 1.14 kg/cm.The acceleration of the vibrations was measured by piezoelectric gages at 300 m intervaIs along the vibrator belt. The signals were integrated twice by the amplifier and recorded on oscillograph tape in the form of lines corresponding w the displacements of points on the vibrator belt.As an example, Fig. 2 shows displacements oscillograms of points on a vibrator belt 300 mm broad, 5 mm thick, with a load of 1.14 kg/cm, for a rotation rate of 1000 rpm. The numbers on the curves correspond to the order of the points from the vibrator towards the discharge end of the belt. The wp oscillogram represents the displacements of a point on the belt above the vibrator. The oscillograms are on different scales.It would be possible to measure the times on these oscillograms, determine the positions of points on curves 1-8, and thus construct the shape of the vibrating belt and thence find the wavelength, the degree of lengthwise damping, etc. However, this is difficult because the oscillograms represent complex, nonsinusoidal periodic vibrations. This is due to various causes, mainly the influence of the base on which the belt lies, together with the superposition of ...
