Closure Strips With Sequential Cuts To Prevent Warping

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Solution Overview

Problem

Prior fastener or closure assemblies made of polyolefins, such as polyethylene or polypropylene, exhibit warping or curling due to elastic memory and recrystallization, leading to inaccurate placement and poor closure of bags or sheets during use.

Innovation Solution

Incorporating sequential cuts outside the fastener or closure elements on the support web to relieve internal stresses and prevent warping, with options for cut placement at the edge or intermediate zones, and adjustable pitch to ensure proper contact with films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If closure assemblies are stored on circular reels, then they can be conveniently stored and transported, but they undergo warping and curling due to elastic memory and recrystallization

Engineering Contradiction:

Improvestorage convenienceVSAvoidwarping and curling

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The support web is divided into multiple segments by introducing sequential cuts along its length. These cuts create discrete sections that can independently relax internal stresses without affecting the entire assembly, thereby preventing warping and curling while maintaining storage convenience on circular reels

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The harmful internal stresses causing warping are extracted from the system by introducing cuts that allow stress relaxation. The cuts remove the constraint that prevents stress relief, enabling the material to release accumulated tensions without deforming the overall assembly shape

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If closure assemblies are unwound from storage reels, then they can be used, but inaccurate placement occurs due to residual warping

Engineering Contradiction:

Improveplacement accuracyVSAvoidcurvature

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

By segmenting the support web into multiple sections through sequential cuts, each segment can independently assume a flat configuration after unwinding. This segmentation prevents the propagation of curvature along the entire assembly, ensuring accurate placement when transferred from storage reels to packaging films

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sequential cuts are made in advance during manufacturing, before the assemblies are stored or used. This preliminary action pre-relaxes the internal stresses and prevents warping from developing during storage and handling, ensuring the assemblies remain flat and accurately placeable when needed

Inventive Principle:

Principle #10Preliminary action

3Reliability

If complementary fastener assemblies are positioned on film, then closure function is achieved, but difficult assembly occurs due to warping

Engineering Contradiction:

Improveclosure functionVSAvoidassembly difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The sequential cuts divide the support web into manageable segments that maintain flatness and stability during assembly operations. This segmentation allows operators to easily position and align complementary fastener assemblies on the film without dealing with warping or curling, thereby simplifying the assembly process while ensuring reliable closure function

Inventive Principle:

Principle #1Segmentation

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 cuts effectively eliminate warping and curling, allowing for accurate and reliable assembly and closure of bags or sheets by relaxing stresses and ensuring proper alignment and contact with films.

Implementation Method 1

the sequential cuts are made in the support web outside the fastener or closure element in order to suppress the effects of warping, curving, or curling of the assembly. The zone of cut implemented in this way in the assemblies allows stresses to relax

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Implementation Method 2

the polymers used for this purpose have elastic memory of their conditions of transformation, and over time they recrystallize, passing through various phases and in the form of different types of crystallite

Methodology Applied

Scientific EffectElastic memory: Elasticity

Implementation Method 3

over time they recrystallize, passing through various phases and in the form of different types of crystallite. This leads to high levels of internal tension causing the assemblies that are stored in this way on circular reels to be subjected to a kind of warping or curling

Methodology Applied

Scientific EffectRecrystallization: Crystallisation

Data Source

PatentUS7604407B2Closure strips for a sheet or a bag, and a resulting sheet or a bag

Publication Date: 2009.10.20 S2F FLEXICO SARL

AI summary

The present invention relates to a fastener or closure assembly for fitting to a sheet or to the mouth of a packaging bag, and comprising at least one fastener or closure strip formed by a support web and a fastener or closure element carried by the web, the assembly including sequential cuts occupying a fraction of the width of the support web of the strip, outside the fastener or closure element and distributed over the length of the assembly in order to suppress the effects of warping, curving, or curling of the assembly.