Cigarette Pack With Mixed Edge Geometry For Wrinkle-Free Overwrapping
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Solution Overview
Problem
Rigid cigarette packs with bevelled or rounded longitudinal edges face issues with overwrapping, as the additional shrinkage required to compensate for 'missing corners' leads to deformation and unsightly wrinkles in the overwrapper, making it impossible to shrink the transparent overwrapper at the upper and lower corners without wrinkles.
Innovation Solution
A pack design with opposed rectangular end faces and a substantially constant transverse perimeter, featuring right-angled portions adjacent the end faces and non-right-angled portions between them, allowing for smooth overwrapping without additional shrinkage at corners or edges, ensuring a wrinkle-free overwrapper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rigid packs have bevelled or rounded longitudinal edges, then ergonomics and reduced garment wear are improved, but the overwrapper creates unsightly wrinkles due to additional shrinkage requirements
Solution Approach 1:
The patent applies parameter changes by modifying the longitudinal edges to have alternating configurations - some edges are bevelled or rounded while others remain substantially right-angled. This selective parameter change allows the pack to maintain ergonomic benefits where bevelled/rounded edges contact garments, while preserving rectangular corner geometry where the overwrapper is applied, thereby eliminating wrinkles without sacrificing ergonomics.
2Shape
If additional shrinkage is applied at upper and lower corners to compensate for missing corners, then the overwrapper fits the pack shape, but the pack deforms inwards and creates unsightly wrinkles
Solution Approach 1:
The patent extracts the problematic bevelled/rounded portions from the longitudinal edges that contact the overwrapper, retaining only substantially right-angled edges at these locations. By removing the non-right-angled geometry where it conflicts with overwrapper application, the need for additional shrinkage is eliminated, preventing both pack deformation and overwrapper wrinkles while maintaining ergonomic benefits at other edges.
3Ease of operation
If the pack has bevelled or rounded longitudinal edges, then consumer comfort is improved, but rectangular folded sections of the overwrapper protrude beyond the pack corners
Solution Approach 1:
The patent applies local quality by differentiating the geometry of longitudinal edges based on their function. Edges that contact garments (typically lateral edges) are made bevelled or rounded for ergonomic comfort, while edges that contact the overwrapper (typically longitudinal edges at upper and lower ends) are kept substantially right-angled. This localized differentiation ensures proper overwrapper alignment and eliminates protruding corners while preserving consumer comfort at contact points.
Data Source
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AI summary
A pack (2) for smoking articles substantially in the form of a rectangular parallelepiped comprises: a pair of opposed major side walls (4, 6); a pair of opposed minor side walls (8, 10); four longitudinal edges (16) between the major (4, 6) and minor (8, 10) side walls; and a pair of substantially rectangular opposed end faces (12, 14) defined by transverse edges of the major (4, 6) and minor (8, 10) side walls. At least one of the opposed substantially rectangular end faces (14) is an open end face defined by free transverse edges of the major (4, 6) and minor (8, 10) side walls, at least one of the four longitudinal edges (16) has a non-right-angled portion (20) and the transverse perimeter of the pack (2) is substantially constant. The pack (2) is preferably formed from a folded blank (22) and the non-right-angled portion (20) is preferably defined by at least three lines of weakness in the blank (22).