Folding Box Closure with Interlocking Lip and Slit

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Solution Overview

Problem

Existing rectangular cardboard folding boxes for packing cakes and pastries lack a secure closure mechanism that allows for multiple openings and closures without requiring tools, and existing solutions are prone to accidental opening due to insecure engagement of the closure components.

Innovation Solution

A folding box design featuring a container portion with a pivotable front wall and a lid portion with a slit, where a foldable cut-out lip on the container's front wall is inserted into the slit on the lid, enabling a snap action for secure closure and easy reopening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a pushing lip with gripping part is used to secure the box closure, then the box can be closed without tools, but the gripping part may inadvertently pivot forward causing the lip to slip out of the opening

Engineering Contradiction:
Improvetool-free closureVSAvoidclosure security
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The front wall is divided into a fixed portion and a movable gripping portion connected by a fold line. This segmentation allows the gripping part to pivot forward for insertion while the fixed portion remains stable, preventing inadvertent pivoting that would cause the lip to slip out.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The box is designed to be closed with the front wall in a predetermined downwardly pivoted position, and the gripping part is pre-configured to pivot forward only when deliberately actuated. This preliminary positioning ensures secure engagement while maintaining ease of operation.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the gripping part is pivoted far to insert or draw out the lip part, then the lip can be inserted into the opening, but the gripping part may not return fully to coplanar position increasing probability of accidental opening

Engineering Contradiction:
Improvelip insertion capabilityVSAvoidgripping part return position
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

A stop element is provided that limits the pivoting motion of the gripping part. This stop prevents the gripping part from pivoting too far, ensuring it returns fully to its coplanar position with the front wall after insertion, thereby preventing accidental opening while maintaining ease of operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If adhesive tape is used to secure the closed box, then the box remains securely closed, but the tape is difficult to remove without a cutter and re-closing is not possible

Engineering Contradiction:
Improvebox closure securityVSAvoidclosure reusability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The closure system uses a dynamic foldable gripping part that can pivot forward and return to its original position, enabling multiple openings and closures. This replaces the static adhesive tape with a reusable mechanical closure that maintains security while allowing repeated use.

Inventive Principle:
Principle #15Dynamics

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 design provides a secure closure that prevents accidental opening while allowing for multiple deliberate openings and closures, ensuring the box remains securely closed during use and handling.

Implementation Method 1

The lip comprises tooth sections having tips which are configured to be inserted in the slit by a snap action enabled by the shape of the slit and the tooth sections

Methodology Applied
Scientific EffectSnap action: Elasticity

Data Source

PatentEP4438510B1A box for packing cakes and pastries
Publication Date: 2025.06.18 CARTONNAGES ROLAND NV
  • EP4438510B1 patent drawingFigure 1~2d
  • EP4438510B1 patent drawingFigure 3a~3c

AI summary

In the unfolded and opened state, the box (1) comprises a container portion (2) and a lid portion (3), the container portion (2) being formed of a base panel (4) and four sidewalls (5-7), the lid portion (3) being formed of a top panel (15) and three sidewalls (16-17), with the top panel being pivotably attached to the rear wall (5) of the container portion by a fold line (8). The front wall (7) of the container portion is pivotable with respect to the base panel (4) while not being attached to the side walls (6) of the container portion, so that the lid portion (3) can be closed with the container's front wall (7) being pivoted downward. Said front wall (7) of the container portion and the front wall (16) of the lid portion are respectively provided with a foldable cut-out lip (20) and a slit (22). The lip comprises tooth sections (28) having tips (29) which are configured to be inserted in the slit by a snap action enabled by the shape of the slit (22) and the tooth sections (28) and by the relative dimensions of the interlocking parts, thereby securing the closure of the box and preventing unwanted or accidental opening whilst still enabling the deliberate opening and re-closing of the box.