Metering hopper with variable speed coaxial lifting screw - for in situ blending prior to controlled flow discharge of particulate material, pref. with PTFE seal between screw and outlet

摘要

A metering hopper or discharging particulate material is fitted with a coaxial screw which can turn fast enough to prevent any discharging from the hopper via a cylindrical outlet. Fresh material is introduced by a screw feed into the outlet alongside the hooper screw. At high screw speedS, the feed is lifted into and recycled in the conical hopper body. Minor quantities of additives, colourants etc. can be added directly into the hopper (at any suitable level) and mixed with the recycling main feed. Slowing of the hopper screw allows mixed material to discharge at a rate inversely proportional to the screw speed. The seal between screw and outlet is enhanced by a sleeve of dry self-lubricating material such as PTFE. Suitable for manually or automatically controlled blending and dosing of granulated and powdered materials for extrusion or moulding.