PET Preform Neck Geometry Control for Aseptic Packaging
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Solution Overview
Problem
Current PET container manufacturing processes result in uncontrollable neck straights, leading to irregularities that compromise handling efficiency and increase downtime in aseptic packaging lines, where precise neck geometry is critical for maintaining sterility and preventing transfer failures.
Innovation Solution
The preform design adjusts the external and internal stretch points relative to the support flange, increasing the distance between them to at least four times the external stretch point's distance from the flange, which reduces deformation and bulging during the blow molding process, resulting in a more cylindrical neck with improved planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional blow molding processes are used with conventional preform geometry, then production is simple and cost-effective, but neck straight geometry becomes uncontrollable with irregularities that compromise handling efficiency
Solution Approach 1:
The preform design applies local quality by creating specific geometric features at the neck region including an external stretch radius and internal stretch radius with defined relationships to the support flange. These localized geometric modifications at critical areas (neck straight, support flange, stretch radii) enable precise control of neck geometry during blow molding without requiring complex changes to the entire preform or molding process.
2Reliability
If neck geometry is optimized for precise handling in aseptic packaging, then transfer failures are reduced, but the complexity of controlling neck straight increases
Solution Approach 1:
The preform is designed with preliminary geometric features (external stretch radius, internal stretch radius, support flange dimensions) that are established during injection molding before the blow molding process. These pre-configured geometric relationships create predictable deformation patterns during subsequent blow molding, ensuring consistent neck straight geometry and reliable container transfer in aseptic packaging operations.
3Ease of manufacture
If stretch points are positioned closer to the support flange, then the blow molding process is simpler, but bulging occurs at the neck reducing gripper effectiveness
Solution Approach 1:
The invention specifies precise parameter relationships for the preform geometry: the external stretch radius is positioned at a first distance from the support flange, the internal stretch radius is positioned at a second distance from the support flange, and these distances maintain a specific ratio (first distance ≥ 4 × second distance). These parameter changes optimize the deformation distribution during blow molding to eliminate neck bulging while maintaining process simplicity.
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 significantly reduces bulging at the neck, enhancing gripper grasping and transport efficiency, and ensures consistent neck geometry, reducing downtime and improving handling in both hot-fill and aseptic packaging lines by maintaining sterility.
Implementation Method 1
configured to form a container by stretch blow molding
Implementation Method 2
PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form
Implementation Method 3
Thermal processing involves heating the material (either amorphous or semi-crystalline) to promote crystal growth
Data Source
AI summary
A preform configured to form a container by stretch blow molding. A finish portion of the preform is at a first end of the preform. The finish portion is a container finish of the container. A support flange is at the finish portion. A tip portion is at a second end of the preform opposite to the first end and is configured to form a container base. A neck portion is adjacent to the support flange, and is configured to form a neck portion. An external stretch radius is at an outer surface of the neck portion. An internal stretch radius is at an inner surface of the neck portion. A first distance is between the internal stretch radius and the external stretch radius and is equal to, or greater than, four times a second distance between the external stretch radius and the support flange.