Pulsating polyurethane hopper used in e.g. chemical, pharmaceutical, plastics and food industries

摘要

This dosing unit for bulk materials comprises a flexible plastic trough-like (i.e. rectangular) feed hopper with a dosing screw in its base. Its slanting walls carry air cushions. These are connected to a source of compressed air, which is used for alternate inflation and deflation. In the new design the cushions form parts of the one-piece, flexible hopper walls, made of solid plastic. When pressurised, they form cavities, surrounded by inner and outer sections of the wall. Only the internal wall is inflated, expanding it towards the interior of the hopper. Preferably, to make each cushion, an e.g. metal plate (10) in moulded into the hopper wall. On its internal surface (i.e. that (11) facing the centre of the hopper), a parting agent is applied, which prevents adhesion of the plastic mass used to make the hopper. There is a connection nipple (8) which reaches through to the inner surface (11). The rear of the plate is bonded to the plastic mass by a bonding agent. Cushions ( 7) are located opposite each other, on facing walls. The hopper itself consists of flexible polyurethane, into which the plate is cast.