Dunnage Web Gap Forming Area Reduces Inflation Stresses
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Solution Overview
Problem
Existing dunnage unit forming processes using preformed plastic webs face issues with undesirable inflation-induced stresses and wrinkles due to unrestrained pouch sides, leading to compromised seals and potential leaks, as the sides of adjacent pouches are connected by perforations that restrict inflation and cause foreshortening.
Innovation Solution
The introduction of a gap forming area between pairs of pouches, which allows for foreshortening and reduces stresses during inflation, is achieved through a frangible connection or perforations that rupture at a lower force than the surrounding lines, facilitating fuller inflation and easier separation of dunnage units in a 'ladder' configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sides of adjacent pouches are connected by perforations to maintain structural integrity, then the web remains stable during handling, but the perforations restrict inflation and cause foreshortening leading to wrinkles and compromised seals
Solution Approach 1:
The web is segmented into multiple pouches separated by gap forming areas, allowing each pouch to inflate independently without restriction from adjacent pouches. The segmentation occurs through frangible connections that separate during inflation, eliminating the foreshortening problem while maintaining web stability during the forming process.
Solution Approach 2:
The frangible connections are extracted from the permanent structure, creating temporary connections that exist only during web handling and formation. These connections are designed to break at predetermined low-force points, removing the restrictive effect on pouch inflation while maintaining structural integrity during manufacturing.
2Volume of moving object
If the pouch sides are unrestrained to allow full inflation volume, then inflation volume increases, but inflation-induced stresses and wrinkles cause compromised seals
Solution Approach 1:
The frangible connections act as intermediaries between adjacent pouches, providing temporary support during web handling that prevents excessive movement, then breaking to allow full inflation. This intermediary structure enables both full inflation volume and seal reliability by eliminating the force transmission that causes wrinkles.
Solution Approach 2:
The web structure includes predetermined frangible connection points that are designed to fail at low forces, cushioning the system against the development of high inflation-induced stresses. These weak points break before stresses can propagate to the seals, preventing wrinkle formation while allowing full pouch expansion.
3Ease of operation
If frangible connections are used to allow pouch separation, then easier separation is achieved, but the connections must rupture at lower force potentially compromising structural integrity
Solution Approach 1:
The web structure exhibits local quality variations with strong seals at critical joints and weak frangible connections at separation points. This localized differentiation of strength properties allows the web to maintain structural integrity where needed while enabling easy separation at predetermined locations through controlled weakness.
Solution Approach 2:
The connection strength parameter is deliberately varied across different locations in the web structure. Frangible connections are designed with lower bond strength parameters compared to permanent seals, creating a gradient of connection strengths that enables selective separation while maintaining overall structural integrity during handling and inflation.
Data Source
AI summary
A web, method, and apparatus for forming dunnage units. The web includes first and second elongated layers. A plurality of seals that hermetically join the first elongated layer to the second elongated layer to form a plurality of inflatable pouches and an inflation channel that is in fluid communication with pouches and is disposed outside of the pouches. An inflation side line of perforations, a gap forming area, and an opposite side line of perforations are arranged in a line between pair(s) of the pouches.