Sheet extrusion die

Abstract

An extrusion die includes a plurality of studs, a tuning assembly and a restrictor member. The tuning assembly comprises a wedge member, first and second adjustment members, and an adjustment controlhaving a rotatable single point adjustment member. The wedge member is coupled to first ends of the studs and includes a first and second plurality of channels within. The first and second adjustmentmembers have a plurality of protrusions, each of which is positioned within a respective one of the first and second plurality of channels. The restrictor member extends in the longitudinal directionand is coupled to second ends of the studs. Rotation of the single point adjustment member causes each of the protrusions to move within each respective channel, forcing the wedge member, the studs, and the restrictor member to move in a direction that is substantially perpendicular to the longitudinal direction.

Description

technical field [0001] The present disclosure relates to dies, and more particularly, to a sheet extrusion die that uses restrictor bars with coordinating assemblies to regulate fluid distribution across the extrusion die. Background technique [0002] Sheet extrusion dies are used to discharge molten polymer into roll sets and can include single or multi-layer dies. A single layer extrusion die delivers a single layer of molten polymer to a roll set, while a multilayer extrusion die delivers at least two layers of molten polymer to a roll set. Molten polymer is forced by pressure out of the vessel through the preland gap to the die lip outlet, and the extrudate is fed to a roll set. [0003] In order to vary the distribution of molten polymer entering the roll set, the shape of the distribution gap can be adjusted through the use of restrictor bars or members. Current restrictor bars have flat flow surfaces and require bending or twisting to affect flow distribution throu...

AI Technical Summary

Problems solved by technology

The limiter bars can only bend gradually, and inexperienced operators often try to adjust the limiter bars in such a way that they cannot be bent, resulting in breakage

Incorrect adjustment of the limiter bar may require additional coordination iterations, may result in a damaged or broken limiter bar and / or cause components of the extrusion die to be out of alignment, and may result in off-spec product

[0004] Alternatively, the operator may also retain the limiter bar profile from a previous run and not redefine it for new materials or operating conditions because doing so would be difficult

Therefore, the operator or subsequent operators end up using other process variables such as mold heating zones or lip regulators to compensate, which results in various process variables working against each other

As such, the current method of regulating fluid polymer distribution using restrictor bars reduces the processing window for high quality products

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