Visco-elastic thermomechanical modelling of CRT glass

CRT (cathode ray tube) is the major component for display purposes, like TV, computer monitor, information board, etc. LG.Philips Displays, a joint venture founded in 2001 between Philips and LG, is the number one supplier of CRT in the world. In order to numerically simulate the CRT glass part production, the linear visco-elastic theory is adopted and the glass structure relaxation is considered (Narayanaswamy model). The thermal analysis includes volumetric heat radiation of glass. The temperature dependent glass heat capacity has been measured, as well as the heat conductivity. The relaxation times of the glass stress and the glass structure have also been measured, among others. The application of the theory has been carried out by means of the finite element method (FEM). 3D product FEM model has been established consisting of the glass and the forming tool (metal) parts. Some measurement (temperature, stresses) has been done to verify the model. The modelling is thermal and structural coupled. Some glass and metal deformation and stress status have been revealed for the first time for the CRT glass manufacturing process. There are many applications of the model established, from the glass product design to the production tool parts design, from the production problem solving, searching the root cause to the production process improvement and optimization. The numerical simulation of the production process is successful which helps us to gain the insight of the process, especially in some phases where the measurement has always difficulties.