Structured Forming Fabric Deep Pockets Yankee Cylinder Contact
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Solution Overview
Problem
Conventional papermaking fabrics have shallow depth pockets, limiting the bulk that can be built into the sheet and resulting in reduced drying efficiency and sheet quality due to high caliper and void volume, which leads to water retention and discontinuous contact with the Yankee cylinder.
Innovation Solution
A structured forming fabric with deep pockets formed by warp and weft yarns, where the compression surface is defined by four sides, three of which are formed by a single yarn knuckle, and one by a combination of weft and warp yarns, allowing for high drying efficiency and maintaining sheet properties like caliper and absorbency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional fabrics with shallow depth pockets are used, then the fabric structure is simple and easy to manufacture, but the bulk that can be built into the sheet is limited and drying efficiency is reduced
Solution Approach 1:
The invention transitions from shallow, two-dimensional pocket structures to deep, three-dimensional pocket configurations. The pockets extend significantly into the fabric thickness, creating substantial void volumes that allow sheets to maintain contact with the Yankee cylinder during drying, thereby improving drying efficiency without complicating the manufacturing process.
Solution Approach 2:
The invention changes the geometric parameters of the pocket structure, specifically increasing pocket depth and void volume while controlling fabric caliper. This parameter optimization allows the fabric to support sheets in a manner that maintains continuous contact with the drying surface, resolving the contradiction between structural simplicity and drying efficiency.
2Device complexity
If conventional fabrics with shallow depth pockets are used, then the fabric structure is simple, but high caliper and void volume lead to water retention and reduced sheet quality
Solution Approach 1:
The invention optimizes the parameters of pocket depth, void volume, and fabric caliper to achieve the right balance. The deep pockets are designed with controlled dimensions that prevent excessive water retention while maintaining sheet quality. The specific geometry of the pockets (defined by four sides with specific yarn configurations) ensures reliable sheet support and contact with the Yankee cylinder.
Solution Approach 2:
The invention applies different structural qualities to different regions of the fabric. The pocket areas provide localized support and water management, while the overall fabric structure maintains appropriate caliper. This local optimization of structure ensures that water is effectively managed in the pocket regions without compromising overall sheet quality.
3Productivity
If deep pockets are created in the structured fabric, then drying efficiency and sheet quality are improved, but the fabric structure becomes more complex
Solution Approach 1:
The invention achieves deep pockets through a systematic three-dimensional weave pattern rather than adding complex surface structures. By utilizing the depth dimension in the fabric construction, the pockets are created as integral parts of the weave, maintaining manufacturing simplicity while achieving the desired deep pocket geometry for improved drying efficiency.
Solution Approach 2:
The invention employs asymmetric weave patterns where warp and weft yarns are arranged differently to create the deep pocket structures. The compression surface is defined by four sides with specific yarn configurations that are not symmetric, allowing deep pockets to form naturally during the weaving process without requiring additional complex structural elements.
Data Source
AI summary
A forming fabric for a papermaking machine has a machine facing side and a web facing side. The web facing side has a structured weave of warp yarns and weft yarns that define pockets on the web facing side. Each pocket is defined by four sides on the web facing side, three of the four sides each being formed by a knuckle of a single yarn, and one of the sides being formed by a knuckle of a weft and of a warp yarn, wherein the weft yarn also defines a bottom surface of the pocket.