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United States Patent 5261740
Douris , ê et al. November 16, 1993

One-piece cylindrical extruder barrel assembled with eccentric converging hopper for receiving molten plastic materials

Mosher , Ê et al. November 16, 1993

Abstract

A one-piece barrel for a hot-fed extruder extends from drive means at its upstream end to its discharge mouth near the downstream end of the feed screw. This one-piece extruder barrel has a split-level, in-feed opening adapted for connecting a strong, reinforcing converging hopper in close tolerance therewith for feeding molten plastic into the extruder barrel through this in-feed opening. A feed screw propels along the barrel molten plastic fed into the barrel through the in-feed opening. The barrel is a one-piece, integral, strong, cylindrical member with an axial bore whose entire length may be finish machined at one time. Such one-time finishing of the entire bore of a barrel is not possible in prior hot-fed extruder barrels, because they were built up from multiple sections assembled end-to-end to form the whole barrel. A one-piece barrel aligns more easily with the feedscrew and prevents leakage by absence of joints and is less expensive to manufacture than costly machining and time-consuming assembly of prior multiple-part, hot-fed extruder barrels. Moreover, the converging hopper is welded into a strong, integral, box-like unit with strong upstream and downstream mounting flanges. The hopper is assembled with close tolerance reinforcement fitting relationship into the relatively large in-feed opening for strengthening the barrel near this opening. This strong hopper spans across the large in-feed opening serving as a reinforcement bridge for this opening.