Fiber Web Curl Control via Precalender Cooling Dwell Time
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Solution Overview
Problem
Existing fiber web production lines face challenges in achieving desired surface properties and bulkiness while minimizing raw material usage, and in controlling curl and reeling defects due to temperature and moisture issues during calendering and drying processes.
Innovation Solution
The method involves cooling the fiber web before calendering using additional cooling means, with a dwell time of at least 200 ms, and utilizing two-sided cooling and moisturizing to control curl, and maintaining a temperature below 55°C for reeling, allowing for efficient calendering and curl control with increased drying capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the fiber web is cooled before calendering, then bulkiness is improved and raw material usage is reduced, but the complexity of the production line increases due to additional cooling means
Solution Approach 1:
The fiber web is cooled before calendering to prevent excessive heat buildup during the calendering process. This preliminary cooling action maintains the bulkiness of the web and reduces the need for raw materials while avoiding the need for complex post-calendering cooling systems.
Solution Approach 2:
The cooling function is extracted from the calendering process itself and performed separately before calendering. This separation allows the calendering process to focus on surface finishing while the cooling process independently manages temperature, reducing overall system complexity.
2Stability of the object's composition
If the fiber web is cooled before calendering, then curl control is improved, but the production line complexity increases due to additional cooling devices
Solution Approach 1:
Cooling is performed before calendering to establish stable temperature conditions that prevent curl formation. By addressing temperature control in advance, the system achieves better curl stability without requiring complex curl correction mechanisms during or after calendering.
3Reliability
If the fiber web is cooled to below 55°C before reeling, then reeling faults are minimized, but the production efficiency may be reduced due to extended cooling time
Solution Approach 1:
The fiber web is cooled to the required temperature below 55°C before reeling to prevent reeling faults such as sticking and coating defects. This preliminary temperature preparation ensures reliable reeling operations while maintaining continuous production flow.
4Manufacturing precision
If the fiber web is cooled intensively before calendering, then surface properties are improved, but energy consumption increases due to intensive cooling requirements
Solution Approach 1:
Cooling is performed before calendering to prepare the fiber web for optimal surface finishing. By cooling the web in advance, the subsequent calendering process can operate more efficiently with reduced energy input, as the cooling load is shifted to a separate pre-treatment stage.
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 effectively achieves high bulkiness with reduced raw material usage, minimizes reeling faults, and optimizes curl control, enhancing the overall efficiency and quality of the fiber web production process.
Implementation Method 1
The fiber web is cooled by cooling device before calendering of the fiber web in the precalender and before in another calender of the production line such that after cooling the fiber web is guided to the pre-calender or to the other calender
Implementation Method 2
the fiber web is cooled by cooling device before calendering of the fiber web in the precalender and before in another calender of the production line such that after cooling the fiber web is guided to the pre-calender or to the other calender
Data Source
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AI summary
The invention relates to a method for producing a fiber web (W), in which method the fiber web (W) is calendered in at least one calender (40; 70). Curl of the fiber web (W) is controlled by cooling the fiber web (W) before calendering the fiber web (W) in precalender (40) and/or in another calender (70). Dwell time between cooling and calendering, which is the time the fiber web (W) run takes from the first point of the cooling device (200) or moistening device (100) to the first calendering nip of the pre- or the other calender (40; 70), is at least 200 ms, preferably 200 - 5000 ms. The invention also relates to a production line for producing a fiber web (W), which comprises at least one calender (40; 70). For controlling the curl of the fiber web (W) the production line comprises at least one cooling device (200) located before a precalender (40) and/or another calender (70) and the distance between the first point of the cooling device (200) and the entering point of the fiber web (W) to first calendering nip of the pre- or the other calender (40; 70) is such that dwell time between the cooling and the calendering is at least 200 ms, preferably 200 - 5000 ms.