Abstract: A new flow and heat transfer theoretical model was established for heating phase of rotational molding process for spherical hollow plastic parts, and numerical computation was performed by means of Fluent software based on the model. Heat conduction of mold, heat conduction of plastic layer and following melting, and convective heat transfer of internal air were coupled for the solution of the model. Heating time, temperature at outer wall of mold and temperature of internal air obtained by numerical computation were in good agreement with those by experiment, and thus the theoretical model was validated. In addition, heating time under different outer heating temperatures, outer convective heat transfer coefficients, and plastic layer thicknesses were calculated so that effects of these parameters on heating time can be determined. And some conclusions were made, such as increasing outer convective heat transfer coefficient could shorten heating time more effectively than raising outer heating temperature.

Key words: rotational molding, flow and heat transfer, melting, numerical computation, Fluent software