MODELLING AND SIMULATION OF THE FOAM FORMATION PROCESS

In order to optimise existing process techniques, it is necessary to achieve a more accurate estimate of the PU material behaviour during the moulding process, before production actually commences. At present, the lack of appropriate material models means that the computer-aided prediction of the mould filling process for PU foam systems with simulation programs is only possible to a limited extent. For this reason, a model is presented of the density development during foam formation, which is based on an experimental characterisation of the foaming process. This model has been implemented in a program for simulating the filling process. In order to assess the quality of the model formulation selected, the calculated mould filling is compared with the results of an experimentally-conducted filling study. The investigations have shown that the mould filling behaviour for foaming processes that are constrained by mould walls can be readily described with the aid of the simulation. For free foaming processes, however, the elastic properties of the foam that develop have been seen to be a key material parameter that will need to be taken into account in future.