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New Constructive Technologies – part two

Published by
World Cement,

Rotobox Planetary Extractor

The rectangular/pentagonal tunnel beam lays at each end on metal/concrete supports out of the silo and holds the extraction gear mechanisms.

The specific shape of the tunnel makes the access to the mechanical components inside very simple, thus facilitating their maintenance or replacement.

The machine is mainly composed of a Planetary Box centrally fixed under the metallic beam and driving the planetary movement of the screw.

The vertical loads of the stored product have no impact on the mechanical elements of the extractor but only on the beam.

An Archimedes screw, bolted to the horizontal output shaft from the planetary box moves radially around the vertical axis of the silo (sweeping) while rotating.

The two engines that drive the screw rotation (gear motor) and the sweeping movement (auxiliary torque motor), are safely installed inside the tunnel beam. While the screw rotation is meant to conveys the product towards the central discharge on the silo floor, the sweeping movement ensures complete horizontal extraction across the whole silo surface.

The extractive screw is made of a conical shape steel solid shaft with welded blades progressive in dia. and pitch. The steel quality of the shaft and blades depends on the product to extract.

An inductive control probe allows stopping the screw under the tunnel beam (parking) in order it to be inspected from the openings on the tunnel floor and ensures an easy restart.

A second control probe gives information on the position of the screw plunged into the stored product anytime.

Two central half-deflectors bolted to the beam, prevent the product from flowing by gravity into the central output of the silo floor and contribute to the regular extraction by the screw.

The extractor is designed to work in full mass and ensure an easy start up in all storage conditions. All interventions of inspection or maintenance to the motors and mechanical components are possible from the inside of the tunnel beam even when the silo is full.

The holes on the silo wall under the tunnel beam allow pulling the screw out of the silo for reasons of maintenance or replacement.

In a logic of the automatic functioning, this machine must be interlocked to a downstream conveyor with equal or higher capacity.

Inside the tunnel beam, a trolley fixed on a monorail, makes the displacement of all the mechanical components very simple, thus helping with their eventual maintenance.

For a more homogeneous flow rate, a frequency inverter, eventually installed between the Planetary Extractor and the downstream conveyor, allows the screw rotation speed to be adjusted according to needs.

This is part two of a two-part article written for World Cement’s December issue and abridged for the website. Subscribers can read the full December issue by signing in, and can also catch up on-the-go via our new app for Apple and Android. Non-subscribers can access a preview of the December 2016 issue here.

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