Rib-Enhanced Inner Preform for Dual Container Molding
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Solution Overview
Problem
In preforms for molding dual containers, the crystallized region in the inner preform can cause thermal expansion of the connecting portion, making it difficult to fit the mouth portion of the inner preform into the outer preform during the molding process.
Innovation Solution
A rib is formed on the inner circumferential surface of the inner preform, adjacent to the crystallized region, which increases the rigidity of the connecting portion and suppresses outward radial expansion, allowing easier fitting of the mouth portions and facilitating injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystallized region is provided in the inner preform to prevent outward expansion during blow molding, then the airway can be secured more easily, but the connecting portion may be thermally expended and the mouth portion may be difficult to fit into the outer preform
Solution Approach 1:
The inner preform is segmented into distinct functional regions: a crystallized region (first region) that resists outward expansion during blow molding, and a connecting portion (second region) that remains flexible for fitting. This segmentation allows each region to perform its specific function without interfering with the other, resolving the contradiction between airway security and fitting ease.
Solution Approach 2:
Different regions of the inner preform are given different local qualities: the first region is crystallized to provide rigidity and prevent radial expansion, while the second region remains non-crystallized or less crystallized to maintain flexibility for fitting into the outer preform. This local differentiation of material properties allows both requirements to be satisfied simultaneously.
2Stability of the object's composition
If the connecting portion is made rigid to maintain structural integrity, then the preform stability improves, but the mouth portion becomes difficult to fit into the outer preform due to thermal expansion
Solution Approach 1:
The preform is divided into a first region with high crystallinity for stability and structural integrity, and a second region with lower crystallinity that remains flexible for the fitting operation. This segmentation allows the preform to maintain overall stability while enabling the necessary flexibility at the connecting portion.
Solution Approach 2:
The degree of crystallinity is changed as a parameter to achieve different mechanical properties in different regions. By controlling the crystallization process to create a gradient or distinct zones of crystallinity, the preform achieves both stability and fitability through parameter differentiation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The rib design ensures that the mouth portion of the inner preform can be easily fitted into the outer preform, even when the crystallized region is present, and provides increased rigidity to prevent fitting difficulties during the molding process.
Implementation Method 1
the inner preform is formed of a crystalline resin, and a crystallized region having a degree of crystallization greater than the other portion is provided in at least a portion of the inner preform adjacent to the mouth portion from below the mouth portion and located below the outside air introduction hole
Implementation Method 2
when heating is performed to form the crystallized region in the inner preform, the portion continuous with the crystallized region from above the crystallized region (hereinafter, a connecting portion) may be thermally expended
Data Source
AI summary
A preform for molding a dual container, in which an inner preform is inserted into an outer preform in a state in which a mouth portion of the inner preform is fitted into a mouth portion of an outer preform, the inner preform is formed of a crystalline resin, a crystallized region is provided in at least a portion of the inner preform, the crystallized region having a degree of crystallization greater than that of the other portion, the portion of the inner preform adjacent to the mouth portion from below the mouth portion and located below the outside air introduction hole, a step portion facing upward and a rib extending upward from the step portion are formed on an inner circumferential surface of the inner preform, and at least a part of the rib is adjacent to the crystallized region from above the crystallized region.