Movable Base for PET Containers Resolving Vacuum Deformation
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Solution Overview
Problem
PET containers face challenges in withstanding pasteurization and retort processes due to their inability to handle the high temperatures and pressures, leading to deformation issues caused by vacuum pressures post-cooling, which complicates lightweighting and design flexibility.
Innovation Solution
A lightweight, flexible base design that can move to accommodate vacuum forces without the need for heavy sidewalls or vacuum panels, allowing the container to maintain a smooth, 'glass-like' appearance and support upright positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy sidewalls or vacuum panels are used to withstand vacuum pressures, then container strength and vacuum resistance are improved, but container weight increases and design flexibility is reduced
Solution Approach 1:
The base portion is designed to be movable between different positions (as-blown, expanded, retracted) to dynamically respond to vacuum forces. The base portion can expand outward to accommodate vacuum pressure and then retract, allowing the lightweight container to withstand vacuum without requiring heavy structural reinforcement.
Solution Approach 2:
The container utilizes a flexible base portion that can deform to accommodate vacuum forces. Instead of using rigid, heavy walls, the invention employs a thin, flexible base that can expand and contract in response to pressure differentials, maintaining structural integrity while minimizing weight.
2Stability of the object's composition
If the base portion is made rigid to support upright positioning, then container stability is improved, but ability to accommodate vacuum forces is reduced
Solution Approach 1:
The base portion transitions between rigid and flexible states dynamically. During normal handling, the base maintains a stable as-blown position for upright support. When vacuum forces are applied, the base can expand to the expanded position to accommodate the pressure, then retract to maintain stability during stacking and transport.
Solution Approach 2:
The base portion is designed as a separate, movable component with distinct functional zones. The primary standing ring provides stable support for upright positioning, while the secondary standing ring and expandable portions provide vacuum accommodation capability, allowing different parts of the base to perform different functions.
3Weight of moving object
If lightweighting is pursued to reduce container weight, then material cost and container weight are reduced, but vacuum performance and structural integrity deteriorate
Solution Approach 1:
The lightweight container achieves vacuum performance through dynamic base movement rather than static structural reinforcement. The base portion can expand outward to accommodate vacuum forces, allowing the use of lighter materials throughout the container while maintaining reliability under vacuum conditions.
Solution Approach 2:
The base portion serves multiple functions automatically: it provides structural support during filling, expands to accommodate vacuum forces during cooling, and maintains stability during stacking. This self-adjusting capability allows lightweight construction without sacrificing vacuum performance or reliability.
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
This solution enables a balance between weight reduction and vacuum performance, eliminating the need for dramatic inversion or snap-through, thus allowing for efficient handling of vacuum pressures and maintaining aesthetic appeal while supporting the container upright.
Implementation Method 1
the creation of a vacuum within the container... If not controlled or otherwise accommodated, these vacuum pressures result in deformation of the container
Implementation Method 2
The cooling reduces the volume of the liquid in the container. This product shrinkage phenomenon results in the creation of a vacuum within the container
Data Source
Figure 1
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Figure 4
AI summary
A container including a finish, a shoulder portion, a sidewall, and a base portion. The finish defines an opening. The shoulder portion extends from the finish. The sidewall extends from the shoulder portion and defines a volume of the container. The base portion is at an end of the sidewall opposite to the shoulder portion. The base portion includes a primary standing ring and a secondary standing ring. The base portion is movable from an as-blown position to an expanded position and from the expanded position to a retracted position. In the as-blown and retracted positions the primary standing ring is configured to support the container upright. In the expanded position the secondary standing ring is configured to support the container upright.