Design and validation of melt valves in polymer processing.

摘要

The new valve designs are proposed for precise control of the polymer melt during processing of critical components produced by hot runner injection molding and extrusion.; The low force valve design works on the key principle of controlling melt flow by regulating the amount of pressure drop in the melt channel. The new design operates on the principle of balanced forces, which greatly reduces the actuation force required to regulate the juncture area, and consecutively controls the volumetric output with an ease of operation. The design has been validated by the series of experiments characterizing the performance of the valve to control the melt flow at a given pressure drop as a function of machine parameters and material properties.; The subsequently derived self-regulatory valve aims to apply melt flow control in polymer extrusion. There are two unique features of this valve; simplicity of design and self contained melt regulation. The valve design regulates flow instability inherent from the extruder, by compensating pressure surges by the movement of a pressurized valve pin and producing a constant output. Experimental validation results show the trade-off between melt pressure and flow regulation. Results also prove the relationship of control forces to obtain desired outputs as a function of melt pressure and temperature. The valve was also advantageously observed to compensate for changes to polymer melt viscosity with respect to the temperature and material type.; These valve designs achieve its distinctive applications in the field of polymer processing by contributing immensely towards greater reliability in the process, taking the manufacturing industry to the next level by implementing controllability of polymer flow.