Defibration Unit With Segmented Rotating Bodies
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Solution Overview
Problem
Current sheet manufacturing processes, particularly in papermaking, face challenges in achieving consistent dry defibration without excessive fiber length reduction, leading to inadequate sheet strength due to the use of wet methods and existing dry methods that shred fibers.
Innovation Solution
A sheet manufacturing apparatus with a defibration unit comprising a rotating unit and a fixing unit, where the rotating unit has protruding sections that contact each other and are designed to minimize fiber cutting, and the fixing unit has corrugated surfaces to enhance air flow and unraveling, allowing for dry defibration without significant fiber shortening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rotating body with saw-toothed protruding bodies is used for scratch-defibration, then defibration can be achieved, but the fibers are excessively shortened and sheet strength becomes inadequate
Solution Approach 1:
The rotating body is segmented into multiple rotating bodies with different functions. The first rotating body has protruding bodies for initial defibration, while the second rotating body has blades for cutting and separating fibers. This segmentation allows each component to perform its specific function optimally without excessively shortening fibers.
Solution Approach 2:
Different regions of the rotating bodies have different local qualities. The first rotating body has protruding bodies with specific shapes (e.g., triangular, rectangular) optimized for scratching and loosening, while the second rotating body has blades optimized for cutting. The gap between rotating bodies is also specifically controlled to achieve the desired fiber separation without excessive shortening.
2Reliability
If wet method is used for defibration, then consistent defibration can be achieved, but water consumption increases and energy for drying is required
Solution Approach 1:
The wet method is replaced with a dry mechanical defibration system. Multiple rotating bodies with specifically designed protruding bodies and blades mechanically separate and cut fibers without using water. This substitution maintains defibration consistency through precise mechanical control while eliminating water consumption and associated drying energy requirements.
3Ease of manufacture
If blades are made to cut into defibration object, then defibration is achieved, but fiber length is excessively reduced
Solution Approach 1:
The system uses dynamic control of the gap between rotating bodies to optimize fiber processing. The gap is specifically controlled to allow fibers to be separated and cut without excessive contact with blades. The rotating bodies operate at optimized speeds to achieve defibration while maintaining fiber length through dynamic mechanical action rather than static cutting.
Data Source
AI summary
A defibration unit includes a rotating unit and a fixing unit. The rotating unit and the fixing unit are arranged so as to be apart from each other with a gap therebetween in a direction that intersects with a rotating shaft of the rotating unit. The fixing unit includes a plurality of plates that are layered in an axial direction of the rotating shaft, and the plates has a plurality of convexities that protrude at a side facing the rotating unit.