Preform having inner partition wall and process of making plastic vessel having inner partition wall
First Claim
1. A preform to be biaxially stretched and blow molded into a plastic vessel, said preform comprising an open top portion, a cylindrical barrel portion, a bottom portion formed to close the barrel portion at the end opposite to the open top and an internal partition wall formed within said barrel portion to extend from one side to the other side of the inner wall and to extend longitudinally from the bottom portion, said preform being characterized by that said internal partition wall has a thickness profile in the transverse direction relative to the longitudinal axis of the preform in which the wall thickness is maximum at the connection between the internal partition wall and the inner wall of the barrel portion, the wall thickness of the internal partition wall is gradually reduced toward the longitudinal center axis of the preform.
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Accused Products
Abstract
A preform (70) has an open top portion (72), a cylindrical barrel portion (74) and a bottom portion (76) formed to close the barrel portion (74) at the end opposite to the open top portion (72). The preform (70) also has an internal partition wall (78) formed to extend across the interior of the barrel portion and from the bottom portion (76). In the transverse direction relative to the longitudinal center axis of the preform (70), the internal partition wall (78) has the maximum wall thickness (a2) at the connection (84) between the inner wall of the barrel portion (74) and the internal partition wall (78), the maximum wall thickness of the internal partition wall being gradually reduced toward the longitudinal center axis of the preform with the minimum wall thickness (a1) at a position (82) near the longitudinal center axis of the preform.
50 Citations
14 Claims
- 1. A preform to be biaxially stretched and blow molded into a plastic vessel, said preform comprising an open top portion, a cylindrical barrel portion, a bottom portion formed to close the barrel portion at the end opposite to the open top and an internal partition wall formed within said barrel portion to extend from one side to the other side of the inner wall and to extend longitudinally from the bottom portion, said preform being characterized by that said internal partition wall has a thickness profile in the transverse direction relative to the longitudinal axis of the preform in which the wall thickness is maximum at the connection between the internal partition wall and the inner wall of the barrel portion, the wall thickness of the internal partition wall is gradually reduced toward the longitudinal center axis of the preform.
- 9. A process of biaxial-stretch blow molding a plastic vessel, said process being characterized by the steps of injection molding a preform having an open top portion, a cylindrical barrel portion having a closed bottom, and an internal partition wall formed to extend from one side of the inner wall of the barrel portion to the other side of the same and to extend longitudinally from the inner face of the closed bottom, stretchedly driving said bottom portion along the longitudinal axis of said preform by the use of a plurality of stretching rods each arranged for the respective one of partitions divided by the internal partition wall of said preform while at the substantially same time stretching said preform in the transverse direction by introducing a pressurized air into the respective divided partitions, the inner end of each of said stretching rods including a tip member arranged therein at a position offset toward the longitudinal center axis of said preform than the center of the corresponding partition, whereby said internal partition wall can be guided by said tip members when said preform is being stretched along the longitudinal axis thereof.
Specification