COMPUTER-AIDED-DESIGN OF WIRE COATING DIES

A nonisothermal analysis of wire coating using the lubrication approximation is presented. The flow problem is solved with the broken section method where the extrusion die is broken perpendicularly to the wire axis. The flow variables (velocity, stresses, and temperature) are computed with a finite difference scheme. Any generalized Newtonian constitutive equation can be used and the energy balance includes convection in the flow direction, viscous dissipation, and conduction through the die and wire. Experimental data for inlet pressure and wire tension, obtained on an industrial line, were compared to simulated results. The predictions were satisfactory and the trends predicted by the model were relatively accurate. The main problem comes from the difficulty of measuring viscosity at high shear rates, corresponding to high processing velocity, with standard techniques. (C) 1994 John Wiley & Sons, Inc.