Method for relofting a nonwoven substrate
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Solution Overview
Problem
Existing methods for relofting nonwoven substrates in absorbent article manufacturing face challenges with infrared heat sources, particularly in managing high acceleration and deceleration rates during assembly line start-ups and shut-downs, leading to unrelofted lengths and potential damage to the substrates.
Innovation Solution
A method and apparatus utilizing a movable axis to selectively direct infrared radiation towards the substrate, ensuring it is only exposed during desired operational conditions, and redirecting the substrate to avoid radiation during start-ups and shut-downs, thereby minimizing unrelofted lengths and substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If infrared heat sources are used to reloft substrates, then substrate thickness is increased, but substrate damage occurs during high acceleration and deceleration rates
Solution Approach 1:
The patent implements a movable axis that can dynamically adjust the position of infrared radiation sources relative to the substrate. This dynamic positioning allows the system to move the substrate out of the radiation path during high acceleration and deceleration events, preventing substrate damage while maintaining the relofting function during normal operation
Solution Approach 2:
The control system monitors substrate acceleration and deceleration rates in real-time and automatically adjusts the axis position accordingly. When high acceleration or deceleration is detected, the system moves the substrate away from the infrared radiation sources, providing feedback-based protection against substrate damage
2Productivity
If infrared radiation is continuously applied to advancing substrates, then relofting efficiency is improved, but unrelofted lengths increase during start-ups and shut-downs
Solution Approach 1:
The movable axis is positioned in advance to optimize infrared radiation exposure during normal operation, ensuring efficient relofting. During start-ups and shut-downs, the system proactively moves the substrate out of the radiation path before damage or unrelofting can occur, preventing waste rather than reacting to it
Solution Approach 2:
The system applies infrared radiation periodically based on substrate speed and operational phase. During normal steady-state operation, radiation is continuously applied for efficient relofting. During transient phases like start-ups and shut-downs, radiation is temporarily suspended by moving the substrate away, creating a periodic on/off pattern that prevents unrelofted lengths
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
Enables efficient relofting of substrates with high acceleration and deceleration rates, reducing waste and maintaining substrate integrity by ensuring precise control over infrared radiation exposure during assembly line operations.
Implementation Method 1
irradiating the first surface of the first length of the substrate with infrared radiation from the first infrared radiation source
Implementation Method 2
Heat may be applied to the web materials in various ways. However, utilizing heat to reloft webs of materials may present various challenges
Data Source
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AI summary
Aspects of the present disclosure relate to methods and apparatuses for relofting nonwoven substrates. During the relofting process, a substrate is directed to advance in a first direction such that a length of the substrate is in a facing relationship with a radiation source. The advancing substrate is relofted by irradiating the length of the substrate with infrared radiation from the infrared radiation source. The substrate comprises a first caliper upstream of the radiation source and the substrate comprises a second caliper downstream of the radiation source greater than the first caliper. The substrate may also be redirected around an axis to advance the substrate in a second direction, wherein the second direction is different than the first direction. The axis may be selectively movable between a first position and a second position to selectively subject the substrate to infrared radiation and remove the substrate from the infrared radiation.