MODELING OF THE BUTT FUSION-WELDING PROCESS

The bead up stage of the butt fusion welding of plastic pipes is modelled by treating the melt layer as a squeeze film containing between two parallel annular rings to which fluid is supplied by the melting of the pipe ends. The lubrication approximation is used to simplify the solution of the governing equations with the melt treated as a non-isothermal power law fulid. Predicted melt layer thicknesses agree well with experimental data over a wide range of operating conditions. Also, this model is used to determine flow characteristics such as the radius of flow separation and the place of zero shear stress in the melt layer, both of which influence the microstructure of the joint. © 1990.