Blow-Molded PET Container Thread Groove Design
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Solution Overview
Problem
Current PET containers face challenges in maintaining material integrity and clarity due to crystallinity issues, and traditional threaded finishes can be heavy and prone to premature tamper-evidence band separation during capping.
Innovation Solution
A blow-molded PET container with a debossed threaded profile and a groove design that reduces material weight, enhances cap stability, and improves tamper-evidence band separation by eliminating material from the container wall and creating a smoother finish for better seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional threaded finishes are used, then cap stability is achieved, but weight reduction and tamper-evidence band separation are compromised
Solution Approach 1:
The threaded finish is segmented by introducing grooves that divide the continuous thread structure into discrete sections. This segmentation reduces material usage and weight while creating distinct zones that facilitate controlled tamper-evidence band separation during capping operations.
Solution Approach 2:
The groove geometry and depth are locally optimized to create specific functional zones: shallower grooves in areas requiring cap stability and deeper grooves where tamper-evidence band separation is desired. This local variation in structure achieves both weight reduction and reliable tamper evidence functionality.
2Manufacturing precision
If debossed threaded profile is used, then improved blown definition and seal integrity are achieved, but manufacturing complexity increases
Solution Approach 1:
Instead of creating raised embossed threads on the mold surface, the invention uses debossed (recessed) groove features in the mold. This inversion simplifies mold manufacturing by eliminating the need for complex material removal or addition processes, while still achieving well-defined threaded profiles on the blown container.
Solution Approach 2:
The groove dimensions, depth, and spacing are carefully controlled within specific parameter ranges to optimize blown definition. By adjusting these geometric parameters during mold design, high precision threaded profiles are achieved without increasing manufacturing complexity.
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 solution achieves significant weight reduction, improved cap stability, and enhanced tamper-evidence band performance, allowing the container to withstand hot-fill processes without distortion and providing a comfortable user interface.
Implementation Method 1
Mechanical processing involves orienting the amorphous material to achieve strain hardening. This processing commonly involves stretching an injection molded PET preform along a longitudinal axis and expanding the PET preform along a transverse or radial axis to form a PET container. The combination promotes what manufacturers define as biaxial orientation of the molecular structure in the container.
Implementation Method 2
Mechanical processing involves orienting the amorphous material to achieve strain hardening.
Implementation Method 3
The thermal processing of an oriented PET container, which is known as heat setting, typically includes 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.
Implementation Method 4
Thermal processing involves heating the material (either amorphous or semi-crystalline) to promote crystal growth.
Data Source
AI summary
A blow-molded plastic container includes an upper portion having a finish, a body portion and a base. At least one groove is formed in a radial sidewall of the finish. The groove slopes gradually downward along the radial sidewall and away from an opening into the container. A method of making the blow-molded plastic container includes disposing a preform into a mold cavity having a surface defining a body forming region, a finish forming region and a moil forming region. The preform is blown against the mold surface to form an intermediate container having a body portion, a finish and a moil portion. The moil is severed from the finish to define the opening into the container. A closure member is adapted to selectively mate with the finish on the container. At least one thread is formed on the closure member.