Tapered Pressing Rolls for Absorbent Web Folding
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Solution Overview
Problem
Existing folding apparatuses for absorbent articles apply excessive stress and cause damage, particularly at the fold origin, due to the narrowing conveying path and rubbing by guides, leading to manufacturing failures like tearing when the conveying speed increases.
Innovation Solution
A folding apparatus with rotating bodies having tapered surfaces and a guide unit that intersects the web's surface, reducing stress by curling side regions towards the central region without direct rubbing, using a conveyor mechanism with suction and guides to maintain accurate folding and prevent width reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conveying path is narrowed from upstream to downstream to enable folding, then the web can be folded with side regions overlapping the central region, but the web width is reduced and large stress is applied at the fold origin
Solution Approach 1:
The pressing rolls are provided with tapered surfaces that have different diameters at different positions. The diameter is larger at the position corresponding to the central region of the web and smaller at the position corresponding to the side edge portion. This local variation in roll diameter allows the central region to receive sufficient pressing force for accurate folding while reducing stress concentration at the side edge portions, thereby preventing web damage.
2Productivity
If the conveying speed is increased to improve productivity, then more web can be processed per unit time, but the rubbing by guides causes more damage at the fold origin
Solution Approach 1:
The patent replaces the traditional guide structure that causes rubbing damage with a suction mechanism. The suction mechanism uses negative pressure to hold and guide the web through the folding process, eliminating the mechanical rubbing contact between guides and the web at the fold origin. This allows high-speed conveying without the damaging rubbing effects that limited previous designs.
3Manufacturing precision
If the conveying path is narrowed to enable folding, then folding can be achieved, but the web becomes narrower in width and stress concentrates at the fold origin
Solution Approach 1:
The pressing rolls feature tapered surfaces with varying diameters along their length, creating localized pressing forces. The larger diameter at the central region provides sufficient pressure for precise folding, while the smaller diameter at the side edge portions reduces stress concentration. This local differentiation of pressing force distribution enables accurate folding while preventing excessive stress at critical locations.
Solution Approach 2:
The patent employs a suction mechanism that uses negative pressure to hold and guide the web during folding. This pneumatic approach replaces mechanical contact that causes stress concentration, allowing the web to be guided through the narrowed conveying path without excessive stress at the fold origin, thereby enabling folding while maintaining web integrity.
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 apparatus minimizes damage during folding by reducing stress and maintaining accurate folding, even at higher speeds, while allowing for stable and precise formation of fold lines without misalignment or unwarranted adhesion.
Implementation Method 1
a rotating body (pressing rolls 121, 122) including a rotational shaft orthogonal to the machine direction and configured to convey the web in the machine direction while pressing the web in a direction intersecting a surface of the web
Implementation Method 2
At least one end of the rotating body has a tapered shape (tapered surfaces 121a, 122a) tapered toward a side edge portion of the web
Implementation Method 3
conveyor mechanism with suction
Data Source
Figure 1
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AI summary
A sailor roll 120 includes pressing rolls 121,122, and a center roll 123 provided between the pressing rolls 121, 122, the center roll 123 configured to press a central region 203 of a web 200. The portions of the web 200 pressed down by the pressing rolls 121, 122 serve as a fold origin from which the web 200 is folded. Each of the pressing rolls 121, 122 has a tapered shape in which the diameter becomes smaller toward the outer side in the cross direction CD In other word, the pressing rolls 121, 122 respectively have tapered surfaces 121a, 122a tapered toward a side region of the web 200.