Web Humidifier Control for Initial Moisture Regulation
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Solution Overview
Problem
Existing sheet manufacturing apparatuses lack the capability for feedback-control of moisture amount in defibrated materials due to the measurement unit being positioned downstream of the moisture adjustment unit, leading to control challenges during the initial transport phase.
Innovation Solution
Implementing a control method that utilizes a thermometer to measure water temperature and a hygrometer to measure ambient humidity, combined with a moisture meter to adjust the humidifier's drive based on these measurements before the web reaches the moisture meter, enabling feedback-control of moisture content in the web.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the measurement unit is disposed downstream of the moisture amount adjustment unit in the transport direction, then feedback-control on moisture amount can be performed, but it is not possible to perform feedback-control during the initial transport phase from when transport is started to when the leading end reaches the measurement unit
Solution Approach 1:
The system performs preliminary actions by measuring water temperature and ambient humidity before the web reaches the moisture meter, and pre-adjusts the humidifier drive accordingly. This allows the moisture amount adjustment unit to be ready for feedback-control immediately when the web arrives, eliminating the control delay period while maintaining reliable feedback-control capability.
2Device complexity
If the measurement unit is disposed downstream of the moisture amount adjustment unit, then the apparatus structure is simplified, but feedback-control cannot be performed during the transport phase before the web reaches the measurement unit
Solution Approach 1:
The control system performs preliminary measurements of water temperature and ambient humidity, and pre-calculates the appropriate humidifier drive settings before the web reaches the moisture meter. This maintains the simplified downstream measurement unit structure while extending reliable feedback-control coverage to include the entire transport phase through predictive adjustment.
3Device complexity
If the humidifier drive is controlled only after the web reaches the moisture meter, then the control system is simpler, but moisture regulation cannot be adjusted during the transport phase
Solution Approach 1:
The control system performs preliminary measurements of water temperature and ambient humidity to predict the required humidifier drive settings before the web reaches the moisture meter. This maintains relatively simple control system architecture while significantly improving moisture regulation precision by allowing adjustments to be made during the transport phase rather than waiting for feedback from the moisture meter.
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 precise moisture regulation in the web, enhancing the mechanical strength and quality of the resulting sheet by forming stable hydrogen bonds between fibers.
Implementation Method 1
a humidifier (15) that humidifies the web by discharging air mixed with water supplied from a tank which stores the water
Implementation Method 2
a heating roller that is positioned downstream of the humidifier in a transport direction of the web and that heats the web to form the sheet from the web
Implementation Method 3
a moisture meter that is positioned between the humidifier and the heating roller and that measures a moisture amount contained in the web
Implementation Method 4
a thermometer that measures a temperature of the water stored in the tank
Implementation Method 5
a hygrometer that measures humidity outside the sheet manufacturing apparatus
Data Source
AI summary
A sheet manufacturing apparatus includes a transport portion that transports a web formed of a material containing fibers, a humidifier that humidifies the web with air mixed with water supplied from a tank, a heating roller that is positioned downstream of the humidifier and that forms a sheet from the web, a moisture meter that is positioned between the humidifier and the heating roller and that measures a moisture amount in the web, a thermometer that measures a temperature of the water in the tank, and a hygrometer that measures humidity. A method of controlling the sheet manufacturing apparatus includes controlling, as a first mode, drive of the humidifier, based on a measurement result by at least one of the thermometer and the hygrometer until when a leading end of the web reaches the moisture meter, and controlling, as a second mode, the drive of the humidifier, based on a measurement result by the moisture meter after execution of the first mode.