Hinged Container Base Structure for Hot-Fill Vacuum Absorption
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Solution Overview
Problem
Current polymeric containers, particularly PET containers, face issues such as sticking to molds during the molding process and inadequate performance under high vacuum conditions created by hot-filled products.
Innovation Solution
A container design featuring a base configuration with a standing ring, diaphragm, and hinges that allows the base to flex inward upon vacuum generation, combined with an injection blow molding assembly that includes a stretch rod and cooling apertures to enhance crystallinity and reduce mold sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal processing is used to increase PET crystallinity for hot-filled applications, then the container can withstand higher temperatures and vacuum pressures, but the base may stick to the mold during the molding process
Solution Approach 1:
The base is divided into multiple walls (first wall, second wall, third wall) connected by hinges, creating a segmented structure that can flex independently. This segmentation allows the base to absorb vacuum forces through controlled deformation rather than rigid adhesion to the mold, preventing sticking while maintaining vacuum resistance.
Solution Approach 2:
The base transitions from a static rigid structure to a dynamic flexible structure with hinges that allow movement. The base can flex between different configurations (expanded to contracted) in response to vacuum pressure, enabling it to withstand vacuum forces without sticking to the mold during the molding process.
2Strength
If the base is made rigid to maintain structural integrity, then the container can withstand vacuum pressure, but the base cannot flex to absorb vacuum forces, causing sticking to the mold
Solution Approach 1:
The base incorporates hinges that enable dynamic flexing between expanded and contracted configurations. This dynamic capability allows the base to maintain structural integrity while adapting to vacuum forces through controlled deformation, preventing both sticking and structural failure.
Solution Approach 2:
The base structure changes its physical parameters (shape, volume, configuration) in response to vacuum pressure. The hinges allow the base to transition between different geometric states, changing from an expanded as-blown configuration to a contracted activated configuration, thereby maintaining structural integrity under varying pressure conditions.
3Reliability
If the base is designed to flex inward to absorb vacuum, then the container can withstand high vacuum conditions, but the base structure becomes more complex with additional hinges and walls
Solution Approach 1:
The base is segmented into multiple walls connected by hinges, creating a modular structure that achieves vacuum resistance through controlled flexing. This segmentation allows each wall to move independently, providing the necessary flexibility to absorb vacuum forces while maintaining a relatively simple overall design based on repeated geometric elements.
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 design effectively reduces mold sticking and enhances vacuum resistance, ensuring improved performance for hot-filled products by allowing the base to absorb vacuum and maintain structural integrity.
Implementation Method 1
In response to a vacuum generated within the container as the hot-fill product cools subsequent to filling and capping the container
Implementation Method 2
PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form. The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form
Implementation Method 3
blow molding a PET preform against a mold heated to a temperature of approximately 250° F.-350° F. (approximately 121° C.-177° C.), and holding the blown container against the heated mold for approximately two (2) to five (5) seconds
Data Source
AI summary
A container blow molded from a polymeric material, which is configured to store a hot-fill product. A first wall extends from a standing ring to a diaphragm of a base. A first hinge is at a first interface between the first wall and the standing ring. A second hinge is at a second interface between a second wall and a third wall extending to a center portion. In response to a vacuum generated within the container as the hot-fill product cools subsequent to filling and capping the container, the base is configured to move inward from an as-blown configuration to an activated configuration to absorb the vacuum by flexing at the first hinge and the second hinge. In the activated configuration, the center portion, the second wall, the third wall, and the second hinge are closer to the finish than in the as blown configuration.