Soft measurement of cavity pressure based on ultrasonic signal

The relationship among the cavity pressure, the main cylinder pressure, melt density and melt temperature was theoretically analyzed. The soft measurement method was established with the ultrasonic signal, the mold temperature and the pressure of the main cylinder as the auxiliary variables, the cavity pressure as the leading variable. The mathematical model of soft measurement was established by the regression method, and the differential evolution algorithm was used for on-line calibration. An experimental platform was constructed to verify the reliability of this method in different conditions and molding process. The output pressure of the soft measurement was compared with the cavity pressure measured by the pressure sensor in the mold. Results show that the maximum error in the soft measurement is no more than 6%, and the lowest correlation coefficient is 0.994.