Projection Roll Assembly for Multi-Directional Sheet Stretching
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Solution Overview
Problem
Conventional methods for stretching sheet materials, such as nonwoven webs and laminates, are limited to imparting elastic properties in only one or two directions, which is insufficient for applications requiring multi-directional elasticity, such as clothing and personal hygiene products that need to conform to the body and allow for free movement.
Innovation Solution
A roll assembly with cylindrical rolls featuring radially extending projections and corresponding recesses allows for multi-directional stretching by engaging discrete portions of the sheet material, enabling the formation of isolated, stretched regions with island-like shapes, thereby providing elasticity in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ring-rolling process with intermeshed grooved rolls is used to stretch sheet material, then elastic properties are improved in machine direction and/or cross-machine direction, but the sheet material cannot achieve elastic properties in multiple directions simultaneously
Solution Approach 1:
The stretching mechanism is segmented into multiple independent roll pairs, each capable of stretching the sheet material in a specific direction. This allows the system to provide elastic properties in multiple directions simultaneously while maintaining manageable complexity through modular design
Solution Approach 2:
Each roll pair is designed to perform multiple functions: stretching the sheet material in its specific direction, controlling the degree of stretch through adjustable parameters, and working in coordination with other roll pairs to achieve multi-directional elasticity. The universal design allows any roll pair to handle different stretching requirements
2Adaptability or versatility
If sheet material is stretched in only one or two directions using conventional methods, then the stretching process is simple and straightforward, but the resulting material lacks the multi-directional elasticity required for applications like clothing and personal hygiene products
Solution Approach 1:
The invention transitions from conventional one or two-directional stretching to multi-dimensional stretching by incorporating multiple roll pairs oriented at different angles. This dimensional expansion enables the sheet material to achieve elastic properties in multiple directions, meeting the requirements for applications like clothing and personal hygiene products
3Adaptability or versatility
If multiple roll pairs are used to achieve multi-directional stretching, then elastic properties in multiple directions are achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Each roll pair is designed with specific local characteristics optimized for its stretching direction, while maintaining overall system compatibility. This allows the complex multi-directional stretching function to be achieved through specialized local components rather than a uniformly complex system
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 solution enables sheet materials to achieve multi-directional stretch properties, significantly improving elasticity beyond conventional methods, allowing for greater flexibility and comfort in applications like clothing and personal hygiene products.
Implementation Method 1
The projections each include an outermost surface portion that is positioned for contacting a discrete portion of the sheet material and for entering a corresponding recess on the opposite roll. The discrete portion of the sheet material is stretched as the projection and the discrete portion of the sheet material enter into a corresponding recess.
Data Source
AI summary
The invention provides a roll assembly including a pair of cylindrical rolls that are positioned in an opposing cooperating relation for receiving a sheet material therebetween. A plurality of projections on at least one of the rolls extending radially outward from a surface thereof and a plurality of corresponding recesses is provided on the other roll. The projections and corresponding recesses are positioned and arranged on the rolls for contacting and engaging a sheet passing between the pair of rolls. The projections each include an outermost surface portion that is positioned for contacting a discrete portion of the sheet and for entering a corresponding recess on the opposite roll. When rolls rotate about their axes, the projections engage the discrete portion of the sheet material which results in the discrete portion entering the recesses with the projections so as to stretch the sheet in multiple directions.