Parent Roll Moisture Gradient for Uniform Tissue Caliper
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-bulk tissue manufacturing processes face challenges in achieving caliper uniformity and energy efficiency due to variations in moisture content and wound-in pressure within tissue rolls, leading to product quality issues and increased energy consumption.
Innovation Solution
Inducing a z-directional moisture gradient in parent rolls by varying manufacturing operations such as vacuum levels, infrared heating, and air flow to balance moisture content and pressure, resulting in more uniform sheet caliper and reduced energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tissue web is over-dried to a moisture level of 0.5-1.5 weight percent to prevent roll slippage and maintain caliper, then product quality and winding stability are improved, but energy consumption increases and the sheet caliper becomes non-uniform throughout the parent roll
Solution Approach 1:
The patent applies local quality by creating a z-directional moisture gradient where different regions of the parent roll have different moisture contents. The core region maintains low moisture (0.5-1.5%) to prevent slippage, while outer regions have higher moisture (2-5%) to reduce energy consumption. This spatial variation in moisture content allows each region to have properties optimized for its specific function within the roll structure.
Solution Approach 2:
The patent changes the moisture content parameter from a uniform value to a gradient distribution. By controlling the drying process to create a moisture gradient in the z-direction (from core to outer regions), the system achieves both winding stability in the core and energy efficiency in the outer regions, while also compensating for pressure-induced caliper variations.
2Reliability
If the tissue web is dried to a constant moisture level of 0.5-1.5 weight percent throughout the parent roll, then roll slippage is prevented, but sheet caliper uniformity deteriorates due to varying wound-in pressure
Solution Approach 1:
The patent creates local quality differences in moisture content across the z-direction of the parent roll. The core region has low moisture (0.5-1.5%) to maintain structural integrity and prevent slippage under high pressure, while outer regions have higher moisture (2-5%) to compensate for lower wound-in pressure and maintain caliper uniformity. This spatially differentiated approach allows each region to address its specific mechanical challenges.
Solution Approach 2:
The patent introduces asymmetry in the moisture distribution, creating a deliberate non-uniform moisture profile that mirrors the non-uniform pressure distribution in the parent roll. The moisture content increases from the core outward, creating an asymmetric gradient that compensates for the asymmetric pressure profile, thereby achieving uniform caliper across the entire roll.
3Use of energy by moving object
If higher moisture levels (2-5 weight percent) are retained in the parent roll, then energy consumption is reduced, but roll slippage and caliper loss occur during winding
Solution Approach 1:
The patent applies local quality by restricting high moisture content (2-5%) to outer regions of the parent roll where wound-in pressure is lower and slippage risk is reduced, while maintaining low moisture (0.5-1.5%) in the core region where high pressure requires lower moisture for stability. This spatial differentiation allows energy efficiency in outer regions without compromising overall winding reliability.
Solution Approach 2:
The patent segments the parent roll into distinct moisture zones: a core region with low moisture for structural stability and outer regions with higher moisture for energy efficiency. This segmentation allows each zone to have moisture content optimized for its specific mechanical environment, preventing slippage in the high-pressure core while reducing drying energy requirements in the lower-pressure outer regions.
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 approach achieves caliper uniformity in the final tissue product and reduces energy costs by optimizing moisture levels and pressure distribution within the parent roll, enhancing product quality and manufacturing efficiency.
Implementation Method 1
a through-drying fabric for removing moisture from the tissue web by evaporation and condensation
Implementation Method 2
a vacuum dewatering unit for removing water from the wet web
Data Source
AI summary
The intrinsic tissue sheet properties of tissue sheets wound into a parent roll during manufacturing can be purposely varied in order to provide a z-directional gradient within the parent roll. For example, the moisture content of the tissue sheet can be made lower in the core region of the parent roll and greater in the outer region of the parent roll. Such gradients can ultimately provide more uniformity of the intrinsic property within the final tissue product.