Headbox Control for Paper Curl via Surface Anisotropy Measurement
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Solution Overview
Problem
Existing paper and paperboard manufacturing processes face challenges in controlling curl, which can lead to undesirable deformations, jams in printing devices, incomplete adhesion in corrugated cardboard production, and reduced strength in cartons, due to the inability to timely and accurately measure anisotropy differences between surfaces during production.
Innovation Solution
Implementing a system that measures anisotropy on both surfaces of the sheet during production and adjusts the headbox operating parameters in real-time to minimize anisotropy differences, using sensors and a controller to monitor and control the curl potential by manipulating parameters such as jet speed, impingement angle, and slice opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If real-time measurement and control of anisotropy is implemented, then manufacturing precision of curl potential is improved, but device complexity increases
Solution Approach 1:
The system implements real-time feedback by measuring anisotropy on both surfaces of the paper sheet during manufacturing and automatically adjusting headbox operating parameters based on the measured differences, enabling closed-loop control of curl potential without requiring complex post-manufacturing laboratory analysis
Solution Approach 2:
The patent replaces traditional mechanical/laboratory-based curl measurement methods with optical or electromagnetic sensing systems that can measure anisotropy non-contactly in real-time during the manufacturing process, reducing the need for physical sample handling and laboratory equipment
2Measurement precision
If laboratory measurement methods are used, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs preliminary measurement of anisotropy differences during the manufacturing process itself, before the paper sheets are completed and sent to laboratories, allowing curl potential to be controlled proactively rather than measured reactively after production
Solution Approach 2:
The patent introduces an intermediate real-time measurement system that bridges the gap between manufacturing process control and final quality verification, using sensors positioned along the paper machine to provide continuous data on anisotropy without requiring removal of samples for laboratory testing
Data Source
AI summary
A method includes receiving a measurement associated with an anisotropy of a first surface and a measurement associated with an anisotropy of a second surface of a sheet of material. The method also includes adjusting an operating parameter associated with a headbox based on the measurements. The headbox is associated with manufacture of the sheet. The operating parameter could include a jet speed, a jet impingement angle, a jet thickness, a slice opening, and/or a slice apron projection. Adjusting the operating parameter could be based on a difference between a measured anisotropy of the first surface and a measured anisotropy of the second surface. For example, the operating parameter could be adjusted to achieve a desired difference between the measured anisotropy of the first surface and the measured anisotropy of the second surface. Multiple headboxes could be controlled, such as when different headboxes are used to produce different layers of a multi-layer sheet.