Triple Layer Press Felt Pin Seam Construction
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Solution Overview
Problem
Conventional press felts require cutting through a top single layer, leading to loose ends that affect the laying of overlying batt layers and reduce seam life.
Innovation Solution
A press felt with a triple layer base fabric configuration that uses a pin seam without cutting through the top layer, featuring a specific weaving pattern with machine direction and cross-machine direction yarns, and batt layers attached via needling or other methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a top single layer fabric is cut to form the seam, then the seam can be constructed, but loose ends are created that affect batt layer laying and reduce seam life
Solution Approach 1:
The base fabric is divided into three separate layers: a bottom layer with loops, a middle layer, and a top layer. This segmentation allows the seam to be constructed without cutting through the top layer, as the pin passes only through the bottom and middle layers, eliminating loose ends while maintaining seam constructability
Solution Approach 2:
The three-layer configuration provides different local functions: the bottom layer provides loop structure for pin insertion, the middle layer provides structural support without requiring cuts, and the top layer maintains surface integrity. This local differentiation resolves the contradiction by allowing seam construction in the bottom/middle layers while preserving the top layer's continuous surface
2Ease of manufacture
If a top single layer fabric is cut to form the seam, then the seam can be constructed, but the loose ends impact the laying of overlying batt layers
Solution Approach 1:
By segmenting the base fabric into three layers where only the bottom and middle layers are penetrated by the pin, the top layer remains continuous and intact. This prevents loose ends from protruding through the top layer and interfering with batt layer laying, while still allowing seam construction through the lower layers
3Ease of manufacture
If a pin seam is used with traditional two-layer fabric, then the fabric can be assembled, but the seam area has reduced strength and shorter life
Solution Approach 1:
The base fabric uses a composite three-layer structure where the bottom layer (with loops), middle layer, and top layer work together. The pin passes through the bottom and middle layers while the top layer remains intact, creating a composite seam structure that distributes stress more effectively and prevents the weakness associated with traditional two-layer pin seams
Data Source
Figure 1
Figure 2~6
Figure 4A~5B
AI summary
A press felt includes: a base fabric comprising a plurality of repeat units, each of the repeat units comprising a plurality of exterior machine direction (MD) yarns, each of which includes an upper run and a lower run merging with seam loops at each end, a plurality of middle MD yarns positioned between the upper and lower runs of the exterior MD yams, a plurality of cross machine direction (CMD) yarns interwoven with the exterior MD yarns and the middle MD yarns in a predetermined regular weave pattern, the seam loops defining the longitudinal ends of the press felt; and a batt layer overlying the base fabric.