Drum and Belt Control for Sheet Startup Stability
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Solution Overview
Problem
Dry type sheet manufacturing apparatuses face challenges in transitioning to a stable operating state upon startup due to issues like web cuts and fiber insufficiency, requiring careful adjustment of operational parameters to prevent these problems.
Innovation Solution
The apparatus includes a drum with openings for fiber discharge, a belt for web formation, and a control unit that adjusts the timing and speed of drum rotation and belt movement to manage web thickness and fiber accumulation, ensuring stable operation by controlling the start-up process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry type sheet manufacturing apparatus is started from a stop state with fibers present in the drum, then the apparatus can resume operation quickly, but web cuts and instability may occur due to improper fiber accumulation
Solution Approach 1:
The control unit initiates drum rotation before belt movement to pre-accumulate fibers on the belt. This preliminary action ensures that sufficient fibers are gathered before the belt starts moving, preventing web cuts and instability during startup while maintaining quick resumption of operation.
Solution Approach 2:
The system dynamically adjusts the timing and speed of drum rotation and belt movement during startup. The drum rotational speed and belt movement speed are controlled to coordinate properly, allowing flexible adaptation of fiber accumulation rate to match downstream processing capacity, thereby ensuring web stability without sacrificing productivity.
2Productivity
If the drum rotates at high speed to increase fiber discharge rate, then productivity improves, but web thickness becomes uneven and web cuts occur
Solution Approach 1:
The control unit implements periodic or staged speed adjustment of the drum and belt during operation. By varying the rotational speed and belt movement speed in a controlled periodic manner, the system maintains high average fiber discharge rate while ensuring uniform fiber distribution and web thickness, preventing web cuts caused by excessive speed.
3Productivity
If the belt moves quickly to increase web formation speed, then productivity increases, but fiber accumulation becomes insufficient leading to web cuts
Solution Approach 1:
The control unit makes the belt start moving after the drum has already accumulated sufficient fibers. This preliminary fiber accumulation ensures that when the belt begins moving at high speed, there is already enough fiber material on the belt to form a continuous web, preventing web cuts while maintaining high web formation speed.
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
This approach prevents web cuts and ensures quick stabilization of the sheet manufacturing process, allowing the apparatus to transition to a stable operating state effectively.
Implementation Method 1
a drum in which a plurality of openings are formed, and discharges fibers by causing the fibers to pass through the openings by rotating the drum
Implementation Method 2
a belt on which the fibers passing through the openings are accumulated, and forms a web by operating the belt
Data Source
AI summary
An accumulating unit that discharges fibers by rotating a drum unit in which a plurality of openings are formed, a second web forming unit that forms a second web by operating a mesh belt, a sheet forming unit that forms a sheet from the second web, and a control unit that performs a start control for operating the accumulating unit and the second web forming unit from the stop state are included. In a case where the start control is performed from a state where the fibers are present in the drum unit, the control unit adjusts a thickness of the second web by controlling at least one of a timing at which rotation of the drum unit is initiated, a rotational speed of the drum unit, a timing at which movement of the mesh belt is initiated, and a movement speed of the mesh belt.