A DUAL SENSING APPROACH TO SIMULTANEOUS TEMPERATURE AND PRESSURE MEASUREMENT FROM INJECTION MOLD CAVITY

摘要

This paper presents the design and performance analysis of a self-energized wireless sensor capable of simultaneous pressure-temperature dual sensing from within a mold cavity. The sensor extracts energy from the polymer melt pressure differential during the injection molding process and uses ultrasonic pulses as the wireless information transmission carrier. Simultaneous acquisition of melt temperature and pressure and differentiation of the two parameters at the signal receiver's end are made possible by variations of two parameters related to the ultrasonic pulses: the number of ultrasound pulses and the carrier frequency. While the pressure is discretized and translated proportionally into a corresponding number of pulses by a threshold modulator, a temperature-sensitive oscillator module converts the melt temperature variations into a shift of the ultrasound carrier frequency. To quantitatively evaluate the effectiveness of transmission and retrieval of the dual sensing data, an analytical model is established that relates the sensor design to the molding process parameters. The developed technique is validated by the experimental data from a real physical model.