Paper Web Transfer Using Polyurethane Belt and Suction Roll
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Solution Overview
Problem
Existing paper manufacturing machines face challenges in transferring paper webs at speed differences greater than 8% without damaging the web, and in maintaining roll alignment and reducing wear on creping wires due to deflection and contact pressures.
Innovation Solution
A method and machine design involving a polyurethane-covered endless belt transferring the web to a textured fabric with a three-dimensional structure, where the textured fabric runs at a lower speed than the belt, and a suction roll aids in web transfer to a drying cylinder, with a controlled transfer nip length and underpressure to minimize web damage and enhance bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If rush transfer is used with speed difference greater than 8%, then bulk is improved, but web damage occurs
Solution Approach 1:
The web is preliminarily prepared by passing through a dewatering nip that reduces moisture content to 40-60% before the rush transfer operation. This preliminary dewatering strengthens the web structure, enabling it to withstand the mechanical stresses of high-speed-difference transfer while achieving the desired bulk through the textured fabric
Solution Approach 2:
The invention changes the moisture content parameter of the web from its initial state to a controlled 40-60% range before transfer. This parameter modification enhances the web's mechanical properties, allowing it to tolerate the shear forces generated by speed differences exceeding 8% during rush transfer to the textured fabric
2Ease of operation
If multiple rolls cooperate in nips, then web transfer is achieved, but roll deflection and wear increase
Solution Approach 1:
The invention extracts the web from the water receiving felt after dewatering and transfers it to an impermeable belt. This separation eliminates the need for complex multi-roll cooperation and alignment, simplifying the system while maintaining effective web transfer capability through a more straightforward belt-conveyance mechanism
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 allows for reliable web transfer at higher speed differences without web damage, improves bulk, and reduces wear on transfer rolls, while maintaining structural integrity and enhancing the three-dimensional structure of the paper web.
Implementation Method 1
a suction roll aids in web transfer
Data Source
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AI summary
The invention relates to a method of producing a structured fibrous web of paper. The method comprises forming a fibrous web and conveying the formed fibrous web on a water receiving felt (5) to a dewatering nip. An endless belt (11) with a polyurethane surface is passed through the nip together with the fibrous web and the water receiving felt (5). After the dewatering nip, the fibrous web is conveyed by the endless belt (11) to an endless textured fabric (12) which is permeable to air and to which the web is transferred from the endless belt (11) in a transfer nip. The textured fabric (12) rans at a lower speed than the endless belt (11). After the transfer to the textured fabric (12), the fibrous web is carried by the textured fabric (12) to a drying cylinder (17). The transfer nip is formed by two rolls of which one is a suction roll within the loop of the textured fabric. The transfer nip has a length which is 5 mm - 40 mm. The endless polyurethane belt (11) has a width that exceeds the width of the textured fabric (12). The invention also relates to a corresponding machine.