Inclined Vibrating Screen

Overview

A vibrating screen separates a stream of crushed rock, ore, gravel or sand into sized fractions. Feed lands on a slightly inclined steel box fitted with mesh decks; the box is shaken hard enough that the material bounces and travels downhill, and every particle small enough to fit through a mesh opening drops through while the rest carries on to the discharge end. This unit is a double-deck inclined screen, so it makes three products at once: oversize off the top deck, a middle cut off the bottom deck, and fines through both.

The shaking comes from the Exciter Unit, a counterweighted eccentric shaft bolted to the Screen Box that spins the whole body in a small circular orbit. The screening surfaces are the tensioned panels of the Screen Media. The box rides on the Spring Isolator mounts, and a belt-coupled Drive Assembly turns the exciter. Feed enters through the Feed Box and oversize leaves over the Discharge Lip lips.

How it works

The drive motor turns the exciter shaft at about 850 rpm through a V-belt. The counterweights on that shaft throw their mass in a circle, and because the exciter is rigidly bolted to the screen box, the entire box follows in a roughly 8 mm circular orbit at 14 Hz. The four spring isolators of the Spring Isolator are soft compared with that frequency, so they let the box vibrate freely while passing very little force into the Support Frame and the foundation.

That orbit does two jobs. It lofts the bed of material clear of the mesh so particles can re-sort by size, with the heavy and fine ones working down to the deck, stratification, and it conveys the bed down the 20° slope toward the discharge. As the bed travels, near-size particles get repeated chances to present themselves to an opening and pass through. The coarse top panel of the Screen Media protects the finer bottom panel and makes the first cut; the bottom panel makes the fine cut. Tension rails and take-up springs keep each panel drum-tight, because a slack screen blinds and tears. The Dust Hood contains airborne dust for extraction, and the Vibration Sensor in the Wiring & Sensors watches the stroke so a thrown counterweight or a failing bearing is caught before the box shakes itself apart.