Online and real-time accurate prediction of tempered glass surface stress during quenching process

Abstract

In order to obtain tempered glass stress quickly and accurately, a new method is proposed for the prediction of glass stress during quenching process with non-contact, online, and real-time analysis technique. Based on the infrared scanning of real-time surface temperature during the glass quenching process, the nonlinear viscoelastic model of glass tempered was established to calculate programmatically the variation laws of glass surface stress during the quenching process. The results show that under different technical parameters, the surface temperature of glass decreases exponentially with time. The surface stress shows the tensile stress at the initial stage and transforms to compressive stress when the glass temperature is below conversion temperature. The compressive stress increases quickly and tends to be stable at about 15 s during quenching. Air pressure, air-grid height, and heating temperature significantly affect the stress of tempered glass, and the tapping speed does not affect the stress of tempered glass. Compared with the measured values by Grazing Angle Surface Polarimeter (GASP) stress meter, the absolute errors of online prediction results do not exceed 5 MPa, and the relative errors are no more than 5%. This research indicates that non-contact, online, and real-time stress prediction technology can be achieved during tempered glass process, which also provide a theoretical basis for the automatic control of the glass tempered parameters.