Asymmetric Pressing Rollers Prevent Paper Stagnation
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Solution Overview
Problem
In paper manufacturing, the soft calender configuration leads to paper stagnation at the nip portion due to pressure, resulting in transfer failures.
Innovation Solution
A sheet manufacturing apparatus with a pressing unit featuring a pair of rollers where the upper roller is positioned downstream in the transfer direction, allowing gravity to aid transfer and preventing stagnation, with adjustable angles and independent rotation for efficient material handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the soft calender is disposed with a virtual line connecting the center of each roller perpendicular to the transfer direction, then the pressing force is effectively applied to the paper, but the paper stagnates in the inlet of the nip portion due to pressure and transfer failure occurs
Solution Approach 1:
The patent applies asymmetry by positioning the upper pressing roller downstream of the lower pressing roller in the transfer direction, creating an asymmetric arrangement that prevents paper stagnation while maintaining effective pressing force. This asymmetric configuration allows gravity to assist the transfer process rather than oppose it.
Solution Approach 2:
The patent inverts the conventional symmetric roller arrangement by placing the upper roller downstream rather than upstream or aligned with the lower roller. This inversion of the traditional configuration resolves the stagnation problem while preserving the pressing function.
2Productivity
If the upper pressing roller is positioned downstream of the lower pressing roller, then gravity aids material transfer and stagnation is prevented, but the device complexity increases due to independent rotation control requirements
Solution Approach 1:
The patent applies dynamics by enabling independent rotation control of the two pressing rollers, allowing the system to adapt to varying operational conditions. This dynamic control capability facilitates efficient material transfer while managing the added complexity through flexible operational parameters.
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
Ensures smooth transfer of the deposited material by leveraging gravity and independent roller control, preventing stagnation and maintaining material integrity.
Implementation Method 1
gravity acts on the deposited material and thus the deposited material is easily transferred to a nip portion of the pair of pressing rollers
Implementation Method 2
a pressing unit configured to press a deposited material that is deposited by the deposition unit
Data Source
AI summary
There is provided a sheet manufacturing apparatus including: a defibrating unit configured to defibrate a material including fibers in the air; a deposition unit configured to deposit at least a part of defibrated materials defibrated by the defibrating unit in the air; and a pressing unit configured to press a deposited material that is deposited by the deposition unit, in which the pressing unit includes a pair of pressing rollers that initially presses the deposited material, and among the pair of the pressing rollers, the pressing roller positioned at an upper portion is positioned on a downstream side of the pressing roller positioned at a lower portion in a horizontal component of a transfer direction of the deposited material.