Analysis of a mechanism suspension to reduce noise from horizontal vibrating screens

A-weighted sound levels around vibrating screens in coal preparation plants often exceed 90 dB. The National Institute for Occupational Safety and Health (NIOSH) is developing noise controls to reduce noise generated by horizontal vibrating screens. Horizontal vibrating screen noise is dominated by sound radiated from the screen body. NIOSH researchers analyzed a mechanism suspension system that could reduce screen body-radiated noise. A finite element (FE) model of the entire screen was used to analyze the screen with the added mechanism suspension. The spring rates for the mechanism suspension were tuned to transmit vibration at the mechanism operating speed while attenuating vibration transmitted from the mechanisms to the screen body at frequencies above 100 Hz. The FE results were used to estimate the A-weighted sound power level radiated by the screen sides and feedbox for various mechanism suspension spring rates. The results indicate that a tuned mechanism suspension could reduce the A-weighted sound power level radiated by the screen body due to gear and bearing forces inside the mechanisms by 7 to 18 dB.