Lightweight Container Base With Radial Straps For Hydraulic Charge-Up
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Solution Overview
Problem
PET containers used for hot fill applications face challenges in resisting fill pressures, absorbing vacuum pressures, and withstanding top loading forces while maintaining shape and structural integrity, especially as they become lighter in material weight.
Innovation Solution
The design incorporates a base configuration with radial straps and a central pushup portion that creates a hydraulic charge-up state when top-loaded, allowing the container to resist deformation and maintain shape by constraining movement and absorbing vacuum forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If PET container material weight is reduced, then manufacturing cost and environmental impact are improved, but ability to resist fill pressure, absorb vacuum, and withstand top loading deteriorates
Solution Approach 1:
The base is divided into multiple functional elements including radial straps extending from the central pushup portion, with each strap containing recesses and ribs. This segmentation allows the lightweight structure to distribute and manage mechanical stresses from fill pressure, vacuum, and top loading across multiple discrete load-bearing elements rather than requiring uniform thick walls throughout the container.
Solution Approach 2:
The container utilizes biaxially oriented PET material with specific crystallinity characteristics combined with the engineered base geometry. The material properties (crystallinity between 20-40%) are optimized to work synergistically with the segmented base structure, providing both lightweight characteristics and sufficient mechanical strength to resist deformation under various loading conditions.
2Strength
If base structure is made more complex to resist deformation, then structural integrity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The base geometry including radial straps, recesses, and ribs is pre-formed during the blow molding process rather than requiring secondary operations. The pushup portion is pre-positioned at the center of the base, and the molecular orientation of the PET material is pre-established through controlled biaxial stretching before filling, allowing the structure to be ready to resist deformation without additional manufacturing steps.
Solution Approach 2:
The container utilizes the hydraulic properties of the filled commodity to enhance structural stability. When filled, the liquid or semi-liquid product creates internal pressure that, combined with the base geometry, provides hydraulic charge-up effect to resist external vacuum forces and top loading, converting the fill process itself into a structural support mechanism.
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 design enhances the container's ability to resist deformation under pressure and vacuum, maintaining its shape and structural integrity while minimizing material weight and cost, thereby improving overall performance.
Implementation Method 1
The combination promotes what manufacturers define as biaxial orientation of the molecular structure in the container
Implementation Method 2
The ability of a PET container to maintain its material integrity relates to the percentage of the PET container in crystalline form, also known as the 'crystallinity' of the PET container
Implementation Method 3
shrinks back to approximately the original starting volume due to vacuum generated during the product cooling phase
Implementation Method 4
The plurality of ribs and the base portion are configured to place the container in a state of hydraulic charge-up when top load is applied to the container after the container is filled
Data Source
AI summary
A container defining a longitudinal axis and a transverse direction that is transverse with respect to the longitudinal axis. The container includes a finish and a sidewall portion extending from the finish. A plurality of ribs are defined by the sidewall. A base portion extends from the sidewall portion and encloses the sidewall portion to form a volume therein for retaining a commodity. The base portion has a contact surface for supporting the container. A plurality of straps extend radially along the base portion away from the longitudinal axis in the transverse direction, each one of the straps defines a strap surface that is closer to the finish than the contact surface. The plurality of ribs and the base portion are configured to place the container in a state of hydraulic charge-up when top load is applied to the container after the container is filled.