Multilayer Container Trimming Laser Moil Removal

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Solution Overview

Problem

The existing methods for removing the moil or dome from multilayer plastic containers after blow molding face challenges in controlling the edge of the intermediate barrier layer placement, leading to compromised recycling of the trimmed moil and delamination issues due to the use of knife blades with abrasive materials.

Innovation Solution

A method involving molding an intermediate container product with a barrier resin layer that extends part-way into the moil, where the upper portion is removed using a laser and the lower portion is trimmed using a plug and cutting tool, such as shear rollers or a laser, to accurately form the container while allowing for recycling of the moil.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If knife blades are used to trim the moil, then the trimming operation can be performed, but delamination occurs at the trim line and the blade experiences excessive wear

Engineering Contradiction:

Improvetrimming operationVSAvoiddelamination at trim line

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the mechanical knife blade trimming system with a laser trimming system. The laser beam (optical/energy field) substitutes for the mechanical blade, eliminating direct mechanical contact that causes delamination and blade wear. The laser vaporizes or melts the material precisely at the trim line without mechanical stress on the layered structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the barrier layer extends into the moil to ensure coverage, then the barrier layer extends throughout the final container product, but the trimmed moil cannot be used as process regrind

Engineering Contradiction:

Improvebarrier layer coverageVSAvoidrecyclability of moil

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent segments the moil removal into two distinct portions: the upper portion containing the barrier layer is trimmed and discarded, while the lower portion without barrier material is removed and recycled as process regrind. This segmentation allows the barrier layer to extend into the moil for coverage while preserving the recyclability of the barrier-free lower portion.

Inventive Principle:

Principle #1Segmentation

3Reliability

If a laser is used for trimming, then delamination and wear problems are reduced, but the device complexity increases

Engineering Contradiction:

Improvereduction of delamination and wearVSAvoidtrimming equipment

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical knife blade system with a laser trimming system. While this increases device complexity by introducing optical equipment, it eliminates the recurring problems of blade wear and delamination. The laser system, though more complex initially, provides superior reliability and reduces maintenance requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables precise removal of the moil portions, reducing delamination and wear, and allows for the recycling of the upper moil portion as process regrind, while maintaining the integrity of the barrier layer throughout the container.

Implementation Method 1

the upper portion of the moil is removed in a laser trimming operation

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

The cutting tool preferably is either a pair of shear rollers or a laser cutting tool

Methodology Applied

Scientific EffectShear stress: Shear Stress

Data Source

PatentUS7481961B2Multilayer container trimming

Publication Date: 2009.01.27 GRAHAM PACKAGING PET TECHNOLOGIES INC

AI summary

A method making a plastic container in accordance with one aspect of the present invention includes molding an intermediate container product having a body and a moil integral with the body. The body is of layered construction that includes at least one layer of barrier resin that extends part-way into but not throughout the moil. The upper portion of the moil, in which the barrier material is absent, is removed for recycling as process regrind. The lower portion of the moil is removed to form the container. In the preferred embodiment of the invention, the upper portion of the moil is removed in a laser trimming operation. The lower portion of the moil is removed in the preferred embodiment of the invention by inserting a plug into the open end or mouth of the container, and employing a cutting tool that is positioned by the plug for accurately trimming of the container product with respect to the mouth of the container. The cutting tool preferably is either a pair of shear rollers or a laser cutting tool.