Adaptation of In-line Ultrasonic Velocimetry to Melt Flow Measurement in Polymer Extrusion
Sprache des Titels:
Pulsed wave velocimetry (PWV) is an ultrasonic technique for measuring velocity profiles in flowing liquids. In capillaries, PWV requires using ultrasound transducers with high center frequencies and a large bandwidth. This type of transducer is restricted to operating temperatures below 50°C. However, in polymer extrusion, velocity profiles of flowing liquids with temperatures up to 250°C are of interest. This contribution describes the development of a new ultrasonic measurement tool, which is fully integrated in a heated capillary die. It enables long-time measurement of the extrudate using the buffer rod technique and active cooling. The developed prototype was successfully validated in an extrusion experiment: the velocity profile of glass-fiber-filled polypropylene was measured immediately after extrusion in a capillary die.