Study of Oscillating Process of Harp Screens

Abstract

The paper presents the results of investigations on the mechanical characteristics of harp screens’ material influence on the screen separation technological parameters. The paper provided a mathematical model of a harp screens’ oscillating process depending on the length of their free area, on the process duty intensity, and on the screened material characteristics. This study found that the amplitude of the relative motion of the rubber strips under load relaxes with the increase of their free areas, and for steel cables, it increases, reaching a maximum at certain values of the technological load. It also had been established that the presence of the load drastically lowers the amplitude of relative motion of the rubber strips, especially in the zone of nondimensional frequencies of the order (0.6–1.4)g, while the amplitude of oscillation of the cable strings in this frequency range varies insignificantly. The use of the rubber-rope strips as working elements of the screening surface makes it possible to increase the “useful screen area” by enlarging the distance between the supports while maintaining high and stable amplitude of the vibration of the strips. The optimization of the mechanical characteristics of the working elements’ material of the harp screens and the conditions of their fixation, provide the intensification of the separation of the sized feed into fractions by eliminating the sticking of the deck plate by clay inclusions and the clogging by “difficult grains”, at the same time it substantially improves the technical and economic parameters of the screening process.