Stepped Interior Preform Finish for Resin Reduction
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Solution Overview
Problem
There is a continuous interest in creating the lightest possible plastic container to maximize cost savings in transportation and manufacturing, while maintaining the ease of processing and structural properties of current designs.
Innovation Solution
The development of a preform for blow-molding that includes a stepped interior surface and a finish portion with a cylindrical body, bevel, and mirror-polished surfaces to minimize resin usage and ensure a tight seal for pressurized contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the container wall thickness is reduced to minimize resin usage, then the weight and cost are reduced, but the structural strength and seal integrity deteriorate
Solution Approach 1:
The patent applies local quality by varying the wall thickness in different regions of the container. The finish portion has a first wall thickness optimized for sealing, while the body portion has a second wall thickness optimized for structural strength. This allows minimal resin usage in non-critical areas while maintaining adequate thickness in critical sealing and structural regions.
Solution Approach 2:
The container is segmented into distinct portions with different wall thickness requirements. The finish portion (with threads and tamper evidence ledge) is separated from the body portion, allowing each to be optimized independently for its specific function rather than using uniform thickness throughout.
2Quantity of substance
If the container wall thickness is reduced to minimize resin usage, then the manufacturing cost is reduced, but the seal integrity and reliability deteriorate
Solution Approach 1:
The finish portion is designed with a specific first wall thickness that is thicker than the body portion's second wall thickness, providing enhanced seal integrity and reliability in the critical closure area where sealing occurs, while using less resin in the body portion.
Solution Approach 2:
The finish portion is pre-formed with integrated sealing features including threads for closure engagement and a tamper evidence ledge positioned to detect opening. This preliminary integration ensures reliable sealing functionality is built-in during molding rather than requiring additional reinforcement.
3Reliability
If the finish portion wall thickness is increased to improve seal integrity, then the sealing reliability is improved, but the overall container weight and resin usage increase
Solution Approach 1:
The patent implements local quality by assigning a greater wall thickness specifically to the finish portion while keeping the body portion thickness lower. This localized thickening provides the necessary seal integrity and closure engagement reliability without unnecessarily increasing the weight of the entire container.
Solution Approach 2:
By segmenting the container into finish portion and body portion with different thickness characteristics, the design optimizes the weight-seal integrity tradeoff by concentrating additional material only where sealing functionality is required.
4Manufacturing precision
If complex polishing techniques are applied to create mirror polished surfaces, then the seal quality is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by specifying a mirror polished surface finish with controlled roughness (Ra 10-100 nanometers) for the sealing surfaces. This quantitative specification provides clear manufacturing guidance and quality criteria without requiring overly complex or subjective polishing processes.
Data Source
AI summary
A finish portion of a preform for rotatably engaging with a closure to seal pressurized contents within an interior of a container formed from the preform. The finish portion includes a cylindrical body that begins at an opening to the interior. The cylindrical body has a base surface, threads extending from the base surface, a tamper evidence ledge, and a handling surface disposed between the threads and the tamper evidence ledge. A stepped interior includes a graduated narrowing of the cylindrical body between the base surface and the handling surface.