Flexible Bonding Roll with Spring Elements
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Solution Overview
Problem
Existing methods for mechanically bonding absorbent article substrates often result in damage such as tears and holes due to high nip pressures, leading to consumer-noticeable defects and increased susceptibility to bond defects as the web basis weight decreases.
Innovation Solution
A method and apparatus using an anvil roll and a bonding roll with pressure applying members, where the bonding roll includes a first pressure applying member with a first spring element and a second pressure applying member with a second spring element, both compressing the substrate to form bonds while minimizing strain and preventing damage by controlling the compression distance and spring constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high nip pressure is applied during mechanical bonding, then bond strength is improved, but substrate damage (tears and holes) increases
Solution Approach 1:
The patent changes the pressure distribution parameters by transitioning from high nip pressure to low contact pressure bonding. The pressure applying members are designed to apply localized pressure only where needed for bonding, rather than applying high pressure across the entire nip region. This parameter change allows bond formation without the excessive pressure that causes substrate damage.
Solution Approach 2:
The bonding system is segmented into discrete pressure applying members (such as pins or points) rather than a continuous high-pressure nip. Each pressure applying member independently applies pressure at specific bonding locations, allowing precise control of pressure application and preventing widespread substrate damage that would occur with high nip pressure.
2Quantity of substance
If web basis weight is decreased to reduce material usage, then manufacturing cost is reduced, but susceptibility to bond defects (tearing and holes) increases
Solution Approach 1:
The patent changes the bonding parameter from high pressure to low contact pressure, which allows thin, low-basis-weight webs to be bonded without exceeding their structural limits. The reduced pressure prevents tearing and hole formation that would occur with traditional high-pressure bonding of lightweight materials.
Solution Approach 2:
The patent replaces the traditional mechanical high-pressure nip bonding system with a low contact pressure system using controlled pressure applying members. This substitution of the bonding mechanism enables reliable bonding of lightweight webs that would be too delicate for conventional high-pressure mechanical bonding.
3Manufacturing precision
If pattern elements with sharp edges are used for bonding, then bond site formation is improved, but web tearing and cutting around bond sites increases
Solution Approach 1:
Instead of using sharp-edged pattern elements that cut into the substrate, the patent inverts the approach by using rounded or blunt pressure applying members. These members apply pressure without sharp edges, forming bonds through compression and heat rather than mechanical cutting, thereby preventing web tearing around bond sites.
Solution Approach 2:
The patent converts the potential harm of pressure application (which could cause tearing with sharp edges) into a beneficial bonding process by using distributed, controlled pressure from multiple pressure applying members. The pressure is applied in a way that promotes bond formation through material yielding and fusion rather than mechanical failure.
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
This approach reduces the likelihood of substrate damage during bonding, allowing for effective bonding without tears or holes, even at higher web basis weights, by managing the pressure applied to the substrates through the use of spring elements with different spring constants.
Implementation Method 1
the first pressure applying member comprises a first spring element; rotating the bonding roll and the anvil roll wherein the first pressure applying member compresses at least a portion of the first substrate forming a bond
Implementation Method 2
the first pressure applying member comprises a first spring element; the first spring element of the first pressure applying member has a first spring constant
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A flexible bonding roll including one or more pressure applying members is configured to operatively engage an anvil roll. The one or more pressure applying members include one or more spring elements. The spring elements allow for the one or more pressure applying members to compress as the pressure applying members are engaged by the outer circumferential surface of the anvil roll. The compression of the pressure applying members allows for relatively reduced damage of substrates and equipment during bonding.