Various processes are available to produce thin flat glass sheets (Floating, Rolling, Overflow-Fusion, FOURCAULT drawing, ASAHI drawing, PITTSBURGH process, Down-Draw process). Depending on the product specifications each process has its pros and cons. Our CFD simulation software NOGRID points allows to model all of these complex processes. Anyway, in this article we present the capability of our software to model the Down-Draw process using our unique 21/2D drawing tool which is fully integrated in our NOGRID points software of course.
The glass flows out of the orifice and is drawn by rollers in the cold area. The draw velocity is higher than the velocity in the orifice, thus the thickness and the width of glass ribbon is decreasing. Depending on the temperature field in the forming area one can adjust the thickness distribution of the final glass sheet.
Figure 1: Temperature profile (left) and thickness profile (right) during drawing a thin flat glass sheet
NOGRID points software is able to compute the real glass flow and temperature distribution in the complete drawing area. It is also possible to perform the drawing process completely in 3D including the orifice for instance. Comparisons with various experimental data have shown the high precision of the simulation of this intricate flow process. The short computation time allows our customers to incorporate the simulation into the design process to find an optimal orifice design, thus saving time and effort in the design phase and increasing product quality.