Neck-ring Compressive Forces for Preform Ejection

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Solution Overview

Problem

The existing injection molding processes for preforms, particularly those made from thermoplastic polyester materials, face challenges in efficiently removing the preform from the mold without causing distortion or deformation, due to the longer cooling time required for the neck-finish portion, which limits the manufacturing cycle time and can lead to irregular sealing surfaces.

Innovation Solution

The reconfigured neck-ring components apply compressive forces to the sealing surface portion in addition to the handling ring and threaded portions, distributing forces over a larger area and ensuring that the polymer is in compression, allowing for earlier removal of the preform without complete solidification of the neck-finish, utilizing conical mating surfaces to prevent leakage and minimize distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the preform is removed from the mold before complete solidification of the neck-finish, then the manufacturing cycle time is reduced, but the sealing surface may become distorted or deformed

Engineering Contradiction:

Improvemanufacturing cycle timeVSAvoidsealing surface integrity

Core Design Contradiction:

Loss of timeVSManufacturing precision

Solution Approach 1:

The neck-ring components are designed to apply compressive forces to the sealing surface portion before complete solidification occurs, maintaining dimensional stability during the critical early removal phase. The conical mating surfaces are pre-configured to guide proper alignment and force distribution

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical state parameters by applying compressive forces that counteract the natural expansion and distortion tendencies of the semi-solid polymer material. The conical surfaces transform the ejection motion into controlled compressive loading

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the cooling time for the neck-finish portion is extended to prevent distortion, then the sealing surface integrity is maintained, but the overall manufacturing cycle time increases

Engineering Contradiction:

Improvesealing surface integrityVSAvoidmanufacturing cycle time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

Compressive forces are applied through the neck-ring components during the removal process itself, providing preliminary stabilization that eliminates the need for extended cooling time. The conical mating surfaces ensure proper force distribution from the outset

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The compressive force application continues throughout the removal process, maintaining continuous support for the sealing surface. The conical surfaces ensure uninterrupted force transmission as the preform is ejected

Inventive Principle:

Principle #20Continuity of useful action

3Loss of time

If the neck-ring components bear against the sealing surface portion during removal, then the preform can be removed earlier without distortion, but the force distribution must be precisely controlled to prevent new deformations

Engineering Contradiction:

Improvemanufacturing cycle timeVSAvoidforce distribution control

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

Conical mating surfaces are used instead of flat or cylindrical surfaces, providing self-aligning geometry that automatically distributes forces evenly across the sealing surface. The conical shape transforms complex multi-directional forces into simple axial compression

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The neck-ring components are designed with specific local features including conical surfaces at critical contact points, ensuring that force distribution is optimized exactly where needed on the sealing surface portion

Inventive Principle:

Principle #3Local quality

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 approach reduces the preform manufacturing time by up to five seconds without risking neck-finish distortions, enabling faster production cycles and maintaining the integrity of the sealing surface for proper closure attachment.

Implementation Method 1

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

utilizing conical mating surfaces to prevent leakage and minimize distortion

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP1986838B1Apparatus for removing a molded article from a mold, and a molded article

Publication Date: 2010.03.31 HUSKY INJECTION MOLDING SYST LTD

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AI summary

Injection molding method, apparatus, and molded product, whereby a lifting structure and/or step is provided with a lifting portion which is configured to contact substantially one half of an end of the molded plastic article along a line substantially perpendicular to the lifting direction. Since the molded plastic article is lifted by its end, the article does not have to be solidified at its interior, thus allowing earlier removal of the article from the mold, reducing cycle time. Preferably, the neck ring engages only an outer circumferential portion of the molded plastic article during a majority of a mold opening stroke. Also preferably, a core-facing surface of the lifting structure forms a vent gap with the core, when in a mold-closed position.