Abstract
The parison formation process is very important during blow molding, because the mechanical strength of the product is influenced by the thickness distribution and depends on parison thickness, diameter and the temperature distribution.
This paper describes the results of experimental and theoretical analysis for the swelling, draw-down and cooling behavior during the parison formation process. The parison temperature distribution is calculated using a one-dimensional unsteady state heat conductive equation and the results agree with experimental values.
With regard to swelling behavior, three parameters whichd efine the time dependence of swelling are evaluated from linear visco-elastic model and they are closely related to the wall shear stress at the die exit. In the case of draw-down behavior, the expresses the extent of draw-down are evaluated and it is closely parameter which related to parison weight, molding time and viscosity at low shear rate.
