Headbox Jet Velocity Vector Profile Measurement
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Solution Overview
Problem
Current paper manufacturing machines face challenges in accurately controlling Fiber Orientation at the headbox due to varying running conditions, which affect the quality and grade of paper, and existing measurement systems struggle to determine Fiber Orientation direction and magnitude, especially in multi-layer products.
Innovation Solution
A headbox jet velocity vector profile system that measures jet velocity at multiple angles simultaneously, calculates velocity vectors, and infers fiber orientation with high accuracy, allowing for real-time profile control and separate measurement of jet velocity vectors in multi-ply products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dry-end measurements are used to determine Fiber Orientation, then measurement capability is provided, but measurement precision deteriorates due to inability to correctly control Fiber Orientation under varying running conditions and difficulty in determining direction and magnitude
Solution Approach 1:
The system performs Fiber Orientation measurement at the headbox jet exit before the paper web is fully formed and before varying running conditions can affect the fiber orientation. This preliminary measurement allows for real-time control adjustments to be made while the fibers are still in their initial orientation state, preventing orientation problems before they occur rather than correcting them after they have developed.
Solution Approach 2:
The system uses jet velocity vector measurement as an intermediary parameter to indirectly determine Fiber Orientation. By measuring the velocity vectors of the jet at multiple angles and calculating the orientation of these vectors, the system obtains Fiber Orientation information without directly measuring the fibers themselves, which would be difficult and imprecise at the dry end.
2Manufacturing precision
If conventional headbox control components are manually adjusted, then ease of operation is maintained, but manufacturing precision deteriorates due to inability to precisely control Fiber Orientation
Solution Approach 1:
The system implements a feedback control mechanism where jet velocity vectors are measured at the headbox outlet, Fiber Orientation is calculated from these vectors, and control signals are sent back to adjust headbox components such as the slice lip or manifold bellows. This closed-loop feedback enables precise control of Fiber Orientation by continuously monitoring and adjusting based on actual measurement data.
Solution Approach 2:
The system replaces manual mechanical adjustment with an automated control system that uses sensors to measure jet velocity vectors and electronically controls headbox components. This substitution of manual operation with automated sensing and control mechanisms enables more precise and consistent Fiber Orientation control without requiring complex manual coordination.
3Measurement precision
If single-angle velocity measurement is used, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately determine velocity vector profile and fiber orientation
Solution Approach 1:
The system divides the measurement task into multiple independent angle measurements. Instead of using a single complex measurement system, the invention uses multiple sensors or a scanning sensor that measures velocity at different angles (e.g., machine direction and cross-machine direction) independently. Each angle measurement is simple, but the combination of these segmented measurements provides complete velocity vector profile information.
Solution Approach 2:
The system transitions from single-angle measurement to multi-angle measurement by adding the angle dimension to the measurement process. By measuring velocity not just in one direction but in multiple directions (angles) simultaneously or sequentially, the system obtains the complete velocity vector profile, which is essential for accurate Fiber Orientation determination.
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 system enables quick and accurate determination of jet velocity and fiber orientation, improving paper quality control by providing stable signals for profile control and allowing for grade changes, reducing mechanical complexity, and maintaining reliability in harsh environments.
Implementation Method 1
Jet velocity is determined by measuring the Doppler shift frequency caused by the jet on a laser beam of coherent electromagnetic energy.
Implementation Method 2
The laser beam is scanned across the width of the jet to determine differences in the jet velocity as a function of width.
Data Source
AI summary
In a papermaking system having a headbox to dispense a jet of liquid and paper forming fibers, an improvement comprising at least one sensor arrangement for simultaneously or sequentially measuring in at least one location the jet velocity or jet flow correlation of the jet at plural known angles relative to the machine direction. The measured data is analyzed to generate a velocity vector profile or velocity direction profile of the jet, and hence to determine the profile of fiber orientation angles laid down in the sheet formed of the jet.