Method of forming the base section of oblong or oval containers and a preform for effecting same

摘要

This relates to the stretch blow molding of a generally rectangular container specifically of an oval or oblong cross section. Customarily, stretch blow molded containers are formed from preforms which generally have a substantially cylindrical body which terminates in a hemispherical end. However, it has been found that in the stretch blow molding of a container of an oval or oblong section, because the sides are much wider than the ends, there is an uneven stretching and distribution of the material of the preform. This particularly relates to a preform having a modified container base forming portion which is of a reduced wall thickness and which includes an intermediate frusto conical part. By so shaping the base forming portion of the preform, correct amounts of material are provided for forming the base construction of a container.