Clamshell Packaging Asymmetric Seal Zone
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Solution Overview
Problem
Conventional clamshell packaging for foodstuff is not airtight, making it unsuitable for maintaining freshness over several days, and existing solutions do not provide a reliable method for sealing the packaging to achieve an airtight state.
Innovation Solution
A clamshell packaging design featuring a line symmetrical seal zone along the circumferential horizontal flange, with abutting flange parts positioned asymmetrically to prevent overlap and ensure a reliable seal, combined with a plastic barrier foil that covers the flange and allows for easy opening, and a method involving a mold for sealing the flange parts together using heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cardboard tray is used for clamshell packaging, then the packaging is simple and inexpensive, but it is not airtight and cannot maintain food freshness over several days
Solution Approach 1:
The packaging combines cardboard tray material with a plastic barrier foil layer to create a composite structure. The cardboard provides structural integrity while the plastic foil provides airtight sealing capability, resolving the contradiction between simplicity and airtight functionality.
Solution Approach 2:
The plastic barrier foil is nested within the cardboard tray structure, extending onto and substantially covering the circumferential horizontal flange. This nested arrangement integrates the sealing function into the existing tray structure without adding significant complexity.
2Strength
If the tray is made with thicker sheet material to provide strength, then the packaging structure is stronger, but the costs of the clamshell packaging increase
Solution Approach 1:
Instead of increasing cardboard thickness to achieve strength, the invention uses a composite structure where a thin cardboard tray is reinforced by the plastic barrier foil layer, maintaining strength while reducing material quantity and cost.
Solution Approach 2:
The plastic barrier foil acts as a thin film that provides both sealing functionality and structural reinforcement to the cardboard tray, eliminating the need for thicker cardboard while maintaining strength.
3Reliability
If the seal zone transitions overlap when pool parts are hinged together, then the sealing may be compromised with channels remaining, but positioning transitions asymmetrically complicates the manufacturing process
Solution Approach 1:
The invention deliberately positions the transitions of abutting flange parts asymmetrically along the hinge line so that they do not overlap when pool parts are hinged together. This asymmetric positioning prevents channel formation and ensures reliable sealing, while the asymmetry is built into the mold design to maintain ease of manufacture.
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 creates a strong, airtight clamshell packaging that reduces material thickness and costs, while ensuring the packaging remains sealed and can be easily opened, maintaining food freshness for an extended period.
Implementation Method 1
a plastic barrier foil arranged in the pool parts and extending onto and substantially covering the circumferential, horizontal flange
Implementation Method 2
a heated frame movable on top of the upper surface, wherein inner dimensions of the frame correspond to the inner dimensions of the horizontal, circumferential flange, such that a second pool part can extend through the frame, while the horizontal, circumferential flange is clamped between the mold and the frame to seal the seal zone together
Data Source
AI summary
A clamshell packaging for airtight packaging of foodstuff includes a tray folded out of a single sheet. The tray has at least two adjacent pool parts, each pool part having a bottom wall and upstanding walls arranged around the circumferential edge of the bottom wall. The adjacent pool parts are hingedly connected to each other along an upper edge of a respective upstanding wall, so the adjacent pool parts can be hinged on top of each other to form a closed box. A circumferential, horizontal flange is arranged to the tray to at least some upper edges of the upstanding walls. A plastic barrier foil is arranged in the pool parts and extends onto and substantially covers the flange. The flange includes a seal zone extending along the length of the flange. The seal zone is line symmetrical along the hinge line at the upper edge of the connected walls.