Press Fabric Warp-Yarn Joining for Uniform Dewatering
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Solution Overview
Problem
Existing paper machine clothing joining processes result in non-uniform air permeability, caliper, and density, leading to differential dewatering and sheet marking issues during paper production.
Innovation Solution
A joining process for paper machine clothing involves cutting and interdigitating warp yarns along the edges of a woven base fabric, followed by temporary heat or chemical bonding to create a joint area with reduced thread density, maintaining uniform permeability and preventing sheet marking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional seam loops and pintle wire joining methods are used, then the fabric ends can be joined together, but the seam region has larger void area resulting in differential dewatering and sheet marking
Solution Approach 1:
The patent applies local quality by creating a thinned portion at the fabric ends where transverse yarn density is reduced, allowing the seam area to have different structural properties than the rest of the fabric. This localized modification enables uniform dewatering characteristics at the seam while maintaining the integrity of the joining process
Solution Approach 2:
The patent changes physical parameters by controlling the thickness of the overlapping joining ends area to substantially match the thickness of the rest of the fabric through pressing during heat application. This parameter control ensures uniform air permeability and eliminates the harmful void area that causes sheet marking
2Strength
If heat is applied to melt bond the threads in overlapping ends, then the fabric is joined together, but the thickness of the overlapping joining ends areas must be controlled to match the rest of the fabric
Solution Approach 1:
The patent applies preliminary action by creating the thinned portion at the fabric ends before the joining process. This pre-preparation of the fabric structure with reduced yarn density at the ends enables subsequent pressing and heat bonding to achieve uniform thickness more effectively, as there is less material to compress and less variation to control
Solution Approach 2:
The patent controls the thickness parameter by pressing the overlapping joining ends areas during heat application to match the thickness of the rest of the fabric. The thinned portion design facilitates this thickness control by reducing the initial thickness difference that would need to be compensated during the joining process
3Reliability
If seam loops are formed on the base fabric, then the fabric ends can be joined, but production time and expense increase
Solution Approach 1:
The patent extracts the complex seam loop formation process and replaces it with a simpler direct joining method. By removing the need to create and manipulate seam loops and pintle wires, the invention streamlines the joining process to essentially overlap and bond the fabric ends directly, significantly reducing production steps and time
Solution Approach 2:
The patent replaces the mechanical seam loop and pintle wire system with a thermal or chemical bonding system. Instead of mechanically interlocking the ends through loops and wires, the invention uses heat or chemical agents to bond the overlapping ends directly to the base fabric, eliminating complex mechanical operations
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 process enhances the life expectancy of paper machine clothing by ensuring uniform air permeability and preventing sheet marking, while reducing production costs and time.
Implementation Method 1
The cut ends opposing and adjoining one another are then temporarily heated bonded or chemically bonded to define a joint area
Implementation Method 2
The cut ends opposing and adjoining one another are then temporarily heated bonded or chemically bonded to define a joint area
Data Source
AI summary
A joining process for an endless or seamed press fabric, the joining process including the step of providing a woven base fabric having a plurality of monofilament yarns including warp yarns extending in a machine direction and weft yarns extending in a cross machine direction, the woven base fabric being cut along one of the weft yarns and having two opposing ends and two side edges. A predetermined number of the weft yarns are removed along each of the two opposing ends to free a plurality of cut ends of the warp yarns, fringing the ends. The plurality of free cut ends of the two opposing ends are interdigitated with each other and the cut ends opposing and adjoining one another are heat bonded to define a joint area.