Abstract:

The relationship between the heat transfer coefficient at the inner surface of uniaxial?rotating cylindrical rotational mold and its mold speed in the heating phase was studied. A simplified heat transfer model was first established for the heating phase of the rotational molding process， and then differential equations for the heat transfer model were resolved using a MATLAB software. The heating time obtained from experiments could be converted to a heat transfer coefficient at the mold inner surface. In the case of the mold being stationary and rotating at higher speeds， the condition of powder inside the mold was determined and constant. The two cases were simulated via the FLUENT software to obtain the heating time， which also could be converted to the heat transfer coefficient at the mold inner surface. The analytical results indicated that when the volume percentage of powders inside mold was 10 %， the heat transfer coefficient at inner surface increased dramatically with mold speed at first and then changed slightly at a mold speed higher than 2 r/min. When the volume percentage of powders inside the mold was 30 %， as mold speed increased， the heat transfer coefficient at the inner surface increased remarkably at first with an increase in mold speed. Then， it increased slowly at a mold speed higher than 5 r/min and reached a maximum value at 20 r/min， followed by a slow decrease at a mold speed higher than 25 r/min.

Key words: rotational mold, heating phase, mold speed, heat transfer coefficient, MATLAB software, FLUENT software