THE EXTRUSION AND INFLATION OF NONAXISYMMETRIC PARISONS

Optimization of resin usage in blow molding necessitates the use of no nround or nonaxisymmetric die tooling. These die geometries are referr ed to as ''ovalized.'' The extrusion and inflation of parisons formed from nonaxisymmetric dies are complex because of the radial thickness dependency. Four die geometries are considered in this work; one axisy mmetric and three nonaxisymmetric. The three nonaxisymmetric dies have one side set at a constant die gap (1.5 mm) and the side rotated 90-d egrees from it, set at progressively increasing die gaps (2.0, 2.5, 3. 5 mm). A methodology is presented for the measurement of the radial pa rison diameter and thickness swell profile for ovalized parisons. The methodology employs a simple mass balance approach between an axisymme tric part and the parison it was blown from. Experimental results are obtained for the radial parison diameter and thickness swell at two ra dial locations. (C) 1994 John Wiley & Sons, Inc.