T-shaped mold with variable thickness of choked flow area and runner design method thereof

Abstract

According to the T-shaped mold with the variable thickness of the choked flow area and the runner design method thereof, on the basis of analysis of melt flow in a runner, a structure with the variable thickness of the choked flow area is adopted for reducing extrusion pressure, a structure with the variable manifold radius is adopted for reducing melt retention time, and under the condition that the flow rate of a melt outlet in the width direction of the runner is uniform, a differential equation that the thickness of the choked flow area changes in the width direction of the flow channel is deduced through the rheology theory, and the thickness of the choked flow area can be obtained by conducting numerical solution and fitting on the equation. And the extrusion pressure and the melt retention time can be remarkably reduced through the flow channel with the variable manifold radius and the variable flow resistance area thickness. Through the design of the size and the shape of the manifold, the melt retention time can be remarkably shortened under the condition that the extrusion pressure is not remarkably increased, and through the design of the length and the thickness of the flow blocking area, the extrusion pressure is adjusted under the condition that the melt retention time is not increased so as to meet different forming requirements.

Description

Technical field [0001] Technical Field The present invention relates to the design mold, and particularly relates to T-die flow channel design method of varistor thickness of the stream area. Background technique [0002] T-die used in the thermoplastic sheet and film extrusion salivation, critical flow channel which is designed to melt in the flow channel width direction of the outlet flow rate is uniform, the residence time of the melt in the flow channel as short as possible. T-die flow path from the inlet region, a manifold, the baffle region, and a relaxation zone forming zone, where the size of the manifold flow channel width along the cross-sectional area and a choke same direction. After the melt into the manifold, while the manifold to flow along the sides of the flow channel, a portion of the melt flow into the baffle zone and the direction of extrusion, the manifold melt volumetric flow rate decreases, the residence time of the melt length; the melt to flow along the s...

AI Technical Summary

Problems solved by technology

The length of the variable choke zone is to keep the manifold section and the thickness of the choke zone constant, and to reduce the length of the choke zone along both sides of the flow channel, but this structure is difficult to apply to actual production; the thickness of the variable choke zone is to keep the manifold section and thickness The length of the choke zone remains unchanged, and the thickness of the choke zone is increased along both sides of the flow channel, but the melt stays for a long time; the structure with a choke rod is improved by adjusting the choke rod and then changing the local gap of the choke zone during molding. The uniformity of the melt outlet flow rate increases the manufacturing cost of the mold. Even if the flow channel is poorly designed, it is difficult to make the melt outlet flow rate uniformity reach the ideal state even if the choke rod is adjusted.

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