Comparison Between a Numerical Model and an Experimental Approach of Preform Infrared Radiative Heating – Recent Results

Abstract : The injection stretch-blow moulding process of thermoplastic bottles requires an heating step before forming. An amorphous preform is heated above the glass transition temperature (80°C for the P.E.T.) using an infrared oven. This step is fundamental in order to determine the thickness distribution along the preform height and then insure high quality bottles. Thus, the optimisation of the infrared oven is necessary. Various experiments have been conducted to characterise the heat source and the semi-transparent properties of the P.E.T. Measurements of air temperature inside the infrared oven and air cooling speed have been processed. These parameters have been implemented in a control volume software that simulates the heating step. The surface temperature distribution of the preform has been measured using an infrared camera. Comparisons between experimental and numerical results for a rectangular sheet and a rotating preform are presented.