Plastic Bottle Neck With Frustoconical Internal Surface
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Solution Overview
Problem
Existing plastic bottle neck designs fail to securely engage and retain insertable fitments, leading to potential removal or shifting during use, which affects sealing and functionality.
Innovation Solution
A neck design with a frustoconical internal surface and constant major diameter external thread, combined with a shoulder that inhibits upward movement of the fitment, ensures secure engagement and retention of the fitment within the bottle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional plastic bottle neck design is used, then the manufacturing process is simple, but the fitment cannot be securely engaged and retained
Solution Approach 1:
The neck is divided into distinct functional zones: an upper portion with a first internal diameter for receiving the fitment, and a lower portion with a second internal diameter for structural support. This segmentation allows each zone to perform its specific function optimally - the upper zone provides secure fitment engagement while the lower zone maintains structural integrity
Solution Approach 2:
Different portions of the neck are given different internal diameters tailored to their specific functions. The upper neck portion has a larger internal diameter to accommodate and secure the fitment, while the lower neck portion has a smaller internal diameter for structural support. This local differentiation of geometric properties enables the neck to simultaneously achieve secure fitment retention and structural stability
2Reliability
If the neck internal diameter is reduced to secure the fitment, then fitment retention improves, but the sealing surface area decreases
Solution Approach 1:
The sealing function is separated from the retention function by creating distinct zones in the neck structure. The upper zone provides a landing surface and engagement area for the fitment, while the lower zone provides the sealing surface. This segmentation allows the sealing surface area to be optimized independently from the fitment retention dimensions
Solution Approach 2:
The solution moves from a single-dimension (uniform diameter) approach to a multi-dimensional approach by varying the internal diameter along the axial dimension of the neck. This creates a frustoconical geometry where the internal diameter changes progressively from the upper portion to the lower portion, enabling both large sealing surface area and secure fitment retention to coexist
3Ease of manufacture
If a uniform thickness neck wall is used, then manufacturing is simplified, but the interaction between the neck and fitment is reduced
Solution Approach 1:
The neck wall thickness is segmented into different zones: a first thickness in the upper portion and a second thickness in the lower portion. This allows the upper neck to provide optimized interaction with the fitment while the lower neck maintains structural integrity, all while remaining manufacturable through standard processes
Solution Approach 2:
Different wall thicknesses are applied to different portions of the neck based on their functional requirements. The upper neck portion has optimized wall thickness for fitment interaction, while the lower neck portion has wall thickness optimized for structural support. This local differentiation of material properties enables both good neck-fitment interaction and structural stability
Data Source
AI summary
An apparatus is provided in the form of a neck for a plastic bottle or other plastic container. The neck includes an external thread with a constant major diameter that can engage with a bottle cap with an internal thread. The neck has an internal surface with an irregular shape where the internal diameter proximate to the top sealing surface is greater than the internal diameter proximate to the side wall of the plastic bottle. The internal surface of the neck engages with a fitment inserted into the neck of the plastic container to prevent movement of the fitment.