Non-Circular Sheet Holes for Tear Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing sheet items are prone to tearing when external forces are applied due to the presence of holes used for binding, as the stress concentrations at circular holes lead to localized tearing.

Innovation Solution

The use of non-circular hole shapes, such as triangular, eccentric, and oval configurations, which distribute stress more evenly across the sheet, combined with a reinforcing strip to enhance tear-out strength, reduces the likelihood of tearing by dispersing forces and minimizing stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If circular holes are used for binding sheet items, then the binding function is achieved, but the sheet items are prone to tearing when external forces are applied

Engineering Contradiction:

Improvetear resistanceVSAvoidstress concentration

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies asymmetry by using non-circular hole shapes (such as triangular, rectangular, or irregular shapes) instead of traditional circular holes. This asymmetric geometry distributes stress more evenly around the hole perimeter, preventing the concentration of forces at specific points that leads to tearing. The non-circular shapes create multiple stress distribution zones that resist tear propagation more effectively.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the geometric parameters of the holes from circular to non-circular configurations. This parameter change includes modifying the shape, orientation, and sometimes the size of holes to optimize stress distribution. By altering these geometric parameters, the sheet item's resistance to tearing is significantly improved while maintaining the binding function.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If holes are added to sheet items for binding, then the binding capability is enabled, but the structural integrity is reduced

Engineering Contradiction:

Improvebinding capabilityVSAvoidstructural integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

By using non-circular hole shapes, the patent maintains binding capability while improving structural integrity. The asymmetric shapes are designed to work with standard binding mechanisms while distributing stresses that would otherwise compromise structural integrity. This allows the sheet item to remain versatile for binding purposes while being more resistant to tearing and structural failure.

Inventive Principle:

Principle #4Asymmetry

3Ease of manufacture

If traditional circular holes are used, then manufacturing is simple, but stress distribution is poor leading to tearing

Engineering Contradiction:

Improvehole formation simplicityVSAvoidstress distribution

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the geometric parameters of holes from circular to non-circular shapes. This parameter change can be implemented using standard punching, die-cutting, or laser cutting processes, maintaining ease of manufacture. The non-circular shapes provide superior stress distribution characteristics, improving reliability without significantly complicating the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10814663B2Sheet item with non-circular holes

Publication Date: 2020.10.27 ACCO BRANDS CORP

AI summary

A sheet system including a sheet having an edge and at least one generally triangular hole positioned adjacent to but spaced apart from the edge. A side of the triangle is oriented generally parallel with the edge of the sheet.