Nested Preform Assembly Radial Interference Fit
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Solution Overview
Problem
Existing preform nesting methods for plastic containers often result in unintended separation during shipping and storage, which defeats the purpose of nesting and requires re-assembly, complicating automation and increasing costs.
Innovation Solution
A plural preform assembly with a radial interference fit at the open ends of the inner and outer preforms, using ribs and notches to maintain a friction fit and prevent separation, eliminating the need for mechanical interlocks or adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If preforms are nested for simultaneous blow molding, then productivity is improved, but the preforms may separate during shipping and storage operations
Solution Approach 1:
The inner preform is nested within the outer preform, with the inner preform's outer surface fitting into the outer preform's inner surface. This nesting arrangement allows multiple preforms to be handled and transported together as a single unit, improving productivity while maintaining stability through the interference fit connection.
Solution Approach 2:
The interference fit acts as an intermediary mechanism between the inner and outer preforms, creating a friction-based connection that prevents separation during handling operations. This frictional engagement serves as the mediating force that maintains the nested configuration without requiring additional fastening components.
2Reliability
If mechanical interlocks or adhesives are used to prevent preform separation, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The nested preform assembly is self-securing through the interference fit between the inner preform's outer surface and the outer preform's inner surface. The friction generated by the interference fit automatically maintains the connection without requiring external fasteners, adhesives, or complex mechanical interlocks, thereby reducing device complexity while ensuring reliability.
3Adaptability or versatility
If preforms are injection molded separately and then assembled, then manufacturing flexibility is improved, but assembly time and labor costs increase
Solution Approach 1:
The inner preform is prepared in advance with an outer surface geometry designed to create an interference fit with the outer preform's inner surface. This preliminary design of the interference fit interface enables rapid assembly without requiring complex joining operations, thereby reducing assembly time while maintaining manufacturing flexibility through separate injection molding of the preforms.
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 ensures that preforms remain nested during processing and shipping, simplifying handling and reducing assembly costs by maintaining a secure, frictional connection without the need for additional materials or complex joining mechanisms.
Implementation Method 1
The inner preform and outer preform are mechanically joined at the respective open ends by a radial interference fit
Data Source
AI summary
A plural preform assembly having nested preforms. The preforms are held together by an interference fit. The interference fit is provided by the friction between the preforms which occurs when the inner preform is inserted into the outer preform. At least one preform may have ribs extending radially towards the other preform. The ribs provided concentricity and interference to hold the preforms together during subsequent operations. The preforms may later be blow molded to provide a bag in bottle or similar container.