Tearable Roll Core Structure for Easy Axial Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing core designs for center-feed rolls, typically made of thick cardboard, are difficult to extract due to their rigid structure, requiring special solutions like perforations or kraft paper strips, which complicate access and make the extraction process time-consuming and prone to tearing issues.
Innovation Solution
A core with a tearable cylindrical wall, composed of overlapping helically wound strips where one strip forms a weakly attached tab accessible from the inside, allowing axial extraction by applying a force between 1000 cN and 2000 cN, enabling the core to be fully removed without radial shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick cardboard core is used to provide structural rigidity for transport, then the core maintains its shape and protects against crushing, but the core becomes difficult to extract from the roll
Solution Approach 1:
The core is divided into two functional parts: an inner tearable strip made of weaker material that can be easily torn axially, and an outer helically wound cardboard structure that provides structural rigidity. This segmentation allows the core to simultaneously achieve ease of extraction through the inner strip while maintaining structural integrity through the outer layer.
2Ease of operation
If perforations are added to the core wall to facilitate extraction, then access to the product is improved, but the core structure becomes more complex and extraction remains difficult due to radial shear force requirements
Solution Approach 1:
Instead of creating perforations that require radial shear force to tear through the helically wound structure, the invention inverts the approach by providing an axial tear line through the inner strip. This allows the core to be torn open by applying force in the axial direction, which is much easier to access and apply, thereby simplifying the extraction process without adding structural complexity.
3Ease of operation
If a kraft paper strip is bonded to the cardboard strip to enable tearing, then extraction is facilitated, but the bonding makes grasping and applying radial shear force difficult
Solution Approach 1:
The invention changes the dimension of force application from radial to axial. By providing an inner strip with a tear line that extends axially through the core, the user can apply tearing force in the axial direction by grasping the protruding end, which is much more accessible and requires less force than applying radial shear force to tear through bonded strips.
4Quantity of substance
If the core diameter is reduced to save material, then manufacturing cost decreases, but the core becomes harder to grasp and tear
Solution Approach 1:
The core is segmented into an inner strip and an outer helical structure, with the inner strip having a protruding end that serves as a grasping element. This segmentation allows the core to maintain a small overall diameter for material efficiency while providing an accessible protruding portion that facilitates easy grasping and axial tearing.
Data Source
AI summary
A core has a cylindrical wall that can be torn axially and is made up of two superposed strips, these strips respectively being an outer strip in contact with the product and an inner strip, these strips being wound on one another and joined together by regions of attachment for example by bonding. At least one of the longitudinal edges of the inner strip is not attached or is weakly attached over a determined width in order, over at least part of its helical length, to form a free and accessible tab facing the outer strip.