A Flow Spreading Method of Melt Extrusion Pressure Driven Full Mesh Gears

Abstract

The invention discloses a flow distributing method adopting melt extrusion pressure to drive full-engagement gears and a flat die head. The method includes the steps that a polymer melt from an extruder is distributed in the axial direction of the gears to fully occupy tooth grooves after meeting a barrier in an input area of a full-engagement gear set so as to force all the gears in the full-engagement gear set to rotate; the polymer melt is conveyed to an output area of the full-engagement gear set along with rotation of the gears; and therefore the extrusion speed is uniformly distributed in the axial direction of the gears. The flat die head comprises a die head transition sleeve, a die head seat and a bush die which are connected in sequence from top to bottom, wherein the full-engagement gear set is disposed in the die head seat, and a sealed space is formed between the outer contour of the full-engagement gear set and the die head seat. The polymer melt with uniform flow speed in the extrusion direction and the direction perpendicular to the extrusion direction can be provided at the same time, the pressure drop in flow channels is small through the method, the melt uniformity in the extrusion flow channels can be improved without an extra regulating rod, and high-quality uniform sheets or thin film materials can be produced directly through the melt.

Description

technical field [0001] The invention relates to the technical field of polymer material forming and processing, in particular to a flow spreading method of melt extrusion pressure-driven full-mesh gears. Background technique [0002] Flat film, thermoformed film and sheet are usually produced continuously on an extrusion line with a flat slit die, and play an important role in plastic products. The difference between sheet and film is the thickness of the article. Those with a thickness greater than 0.5mm are generally called sheets, and those with a thickness of less than 0.5mm are called films. In the process of processing, the melt is generally cylindrical when it is extruded from the extruder. To transform it into a flat rectangular cross-section and have an equal fluid, it is necessary to form a cavity inside the die for distributing the fluid. According to the cavity Flat dies are usually divided into T-shaped dies, fishtail dies and hanger-shaped dies, etc., and the...

AI Technical Summary

Problems solved by technology

However, the sudden reduction of the cross-sectional area of ​​the flow channel between the manifold and the slit area in the distribution flow channel of the traditional coat hanger type die will cause a large change in the velocity distribution in the flowing fluid, so that the fluid will generate great turbulence and The pressure drop will increase the power consumption of the processing equipment and may affect the quality of the product, which makes the structure very unsatisfactory. Industrial applications require more adjustment of the die lip or adjustment rod, and are sensitive to changes in flow rate.

Especially for sheets with a wide width, the following problems will occur: uneven melt flow rate; wide runners require sufficient clamping force, and many screws need to be designed to ensure that the die head does not leak material; The pressure is also high, and the machine head is easy to deform

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