Web Transfer Roller Wrap Angle for High-Speed Calendering
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Solution Overview
Problem
Existing methods for conveying and treating nonwoven webs at high production speeds result in high forces that can lead to web tearing and reduced strength transverse to the machine direction, due to insufficient energy transfer and poor bonding point quality during calendering.
Innovation Solution
Conveying the web over a transport surface and a rotating transfer roller, allowing it to wrap around the transfer roller at a specific angle before being transferred to a treatment roller, which reduces detachment force and increases dwell time for effective compaction and thermal bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the web is conveyed at high production speeds through the calender, then productivity increases, but the detachment force increases causing web tearing and reduced transverse strength
Solution Approach 1:
The web is pre-conditioned by wrapping around the transfer roller at a controlled wrap angle (15°-90°) before entering the calender. This preliminary action allows the web to gradually adapt to the treatment conditions and reduces the sudden detachment force that would otherwise occur at high production speeds, thereby preventing web tearing while maintaining high productivity
Solution Approach 2:
The wrap angle parameter is optimized to a specific range (15°-90°) to control the detachment force. By adjusting this geometric parameter, the system achieves an optimal balance between production speed and web strength, allowing high-speed operation without exceeding the web's mechanical strength limits
2Productivity
If the dwell time in the calender is insufficient at higher speeds, then productivity increases, but the energy transfer to the web becomes unsatisfactory reducing bonding point quality
Solution Approach 1:
The web undergoes preliminary wrapping and conditioning on the transfer roller before calendering, which prepares the web structure for more effective energy absorption during the subsequent brief calendering process. This pre-conditioning ensures that even with reduced dwell time at high speeds, the bonding points achieve adequate quality
Solution Approach 2:
The wrapping process creates a continuous engagement between the web and the transfer roller, ensuring that energy transfer and bonding actions occur continuously throughout the wrap angle range rather than as a discrete event, thereby maintaining bonding quality even at high production speeds where dwell time is limited
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 minimizes the detachment force, prevents web damage, and achieves optimal strength transverse to the travel direction, even at high production speeds, without significant additional effort or expense.
Implementation Method 1
the web initially follows the rotation of the transfer roller downward, thus resulting in it wrapping around the transfer roller over a wrap angle α
Implementation Method 2
the nonwoven web is then normally compacted, particularly by thermal bonding in a calender comprising, for example, two heated calender rollers
Data Source
AI summary
A method of conveying and treating a web, wherein the web is first conveyed over a transport surface and then over a rotating transfer roller at the end of the transport surface. The web is transferred from the transfer roller to a treatment roller at a spacing from the transfer roller. The conveying of the web is performed with the proviso and particularly a spacing a between the transfer roller and the treatment roller is set such that the web wraps around the treatment roller over a wrap angle α from 15° to 90°.