Folding Cardboard Box with Convex Weakening Line for Effortless Opening

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Solution Overview

Problem

Existing cardboard containers for free-flowing goods require excessive force to open the lid for the first time, which can damage the container and make it difficult to reopen, due to the inconvenient alignment of the tear-off strip and pivot point.

Innovation Solution

A weakening line with a convex course is introduced in the folding carton, allowing easy opening by distributing force uniformly, and designed as a perforation or tear-open thread, which breaks sequentially to indicate correct opening and provide a tamper-evident closure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the outer layer between the second end of the tear strip and the pivot point of the cover element is provided with a straight weakening line, then the tear strip can be aligned directly with the pivot point, but excessive force is required to open the cover element which can damage the container

Engineering Contradiction:
Improvealignment of tear strip with pivot pointVSAvoidcontainer integrity during opening
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The weakening line is designed with a convex course instead of a straight line. This curvature distributes the opening force more uniformly along the tear path, preventing concentration of stress at any single point. The convex shape allows the cover element to be opened effortlessly while maintaining container integrity, resolving the contradiction between ease of operation and strength.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Ease of operation

If excessive force is applied to open the cover element, then the cover element can be opened, but the cover element or the area around the pivot point can be damaged

Engineering Contradiction:
Improveopening of cover elementVSAvoidreusability of container
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The weakening line is pre-formed in the outer layer before use. This preliminary preparation creates a controlled tear path that guides the opening force, eliminating the need for excessive force during actual opening. The pre-formed weakening ensures the cover element can be opened reliably without damaging the pivot point or surrounding areas, maintaining container reusability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The weakening line changes the material parameters of the outer layer along its path, creating a region of reduced strength that is optimized for tearing. By modifying the physical state of the material (creating perforations or score marks), the opening force required is reduced to a safe level that prevents damage to the cover element and pivot point, ensuring the container can be reopened.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the weakening line is designed as a perforation, then the opening force is reduced and tearing is controlled, but additional manufacturing steps are required

Engineering Contradiction:
Improveforce required to openVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The weakening line is created by perforating, score-marking, or partially cutting the outer layer, which changes the material parameters along the tear path. These modifications create controlled weak points that reduce the force needed to open while maintaining structural integrity. The manufacturing processes (perforation, scoring, partial cutting) are standard techniques that balance ease of opening with manufacturing feasibility.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2129585B1Two-part folding cardboard box having a pivotable cover element
Publication Date: 2011.04.20 HENKEL KGAA
  • EP2129585B1 patent drawingFigure 1~2
  • EP2129585B1 patent drawingFigure 3~4
  • EP2129585B1 patent drawingFigure 5

AI summary

The invention relates to a container, particularly for pourable products such as detergents, comprising an outer layer (2), said outer layer (2) forming an outer box, comprising at least six walls, a cover element (4) that swings open, wherein the cover element (4) is configured as part of the outer box (2), an inner layer (3), wherein at least two segments (3a, 3b, 3c, 3d, 3e) of the inner layer (3), which can be folded toward each other, are each disposed parallel to at least two walls of the outer layer (2), and the outer layer (2) comprises at least one strip element (5) that can be torn off, by means of which an edge region of the cover layer can be exposed for the purpose of forming a first opening of the container (1), wherein part of the cover element (4), when closed, covers the inner layer (3) at least partially, wherein the strip element (5) that can be torn off comprises a first end (14) and a second end (15), which is configured as a weakening line (9) between the second end (15) and the pivot point (16) of the cover element (4), wherein the weakening line (9) has a course that deviates from the direct, straight connection (17) between the end point (15) of the strip element (5), which can be torn off, and the pivot point (16) of the cover element (4).