Patent ID: 6248413
Filing Date: 2001-06-19
Classification: B29B,B29C,B29K,Y10T

Abstract:
A preform for forming a container having a base with a central bottom and a lowermost seating surface having an annularly shaped contact with a supporting surface, said preform comprising:an upper neck portion;a middle body forming portion;a lower base forming portion having a substantially hemispherical bottom part for forming the central bottom of the container, said substantially hemispherical bottom part having an external diameter and an internal diameter;an intermediate portion between said middle body portion and said lower base forming portion, said intermediate portion comprising a frustoconical part with inner and outer surfaces that, as seen in cross section, extend straight at an angle to a central axis of said preform, said intermediate portion having an outer diameter and an inner diameter that both become smaller along said frustoconical part, and said intermediate portion being of substantially uniform thickness;wherein the height at which the outer diameter of said intermediate portion begins to become smaller is higher than the height at which the inner diameter of said intermediate portion begins to become smaller; andwherein the outer diameter of said intermediate portion reduces to the external diameter of said hemispherical bottom part and the inner diameter of said intermediate portion reduces to the internal diameter of said hemispherical bottom part, the height at which the outer diameter of said intermediate portion reduces to the external diameter of said hemispherical bottom part being higher than the height at which the inner diameter of said intermediate portion reduces to the internal diameter of said hemispherical bottom part.