Multi-Ply Forming Section Dry Content Control
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Solution Overview
Problem
The existing forming sections for producing multi-layer fibrous webs often result in suboptimal ply strength, leading to potential delamination during processing or in the finished product, particularly in multi-layer cardboard production, where basis weight variations complicate setting of process parameters.
Innovation Solution
A forming section equipped with a control device that measures and adjusts the dry content of each fibrous web layer before couching, using sensor devices and controllable dewatering elements like vacuum suckers to maintain a specific dry content differential between layers, ensuring optimal layer strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple headboxes and forming fabrics are used to produce multi-layer fibrous webs, then the productivity and versatility of the machine is improved, but the ply strength and layer bonding quality deteriorate due to difficulty in controlling dry content uniformity
Solution Approach 1:
The patent implements a feedback control system where moisture sensors continuously measure the dry content of each fibrous web layer, and the control device adjusts the dewatering elements (vacuum boxes, forming bars) in real-time to maintain optimal dry content differential between layers, ensuring consistent ply strength
Solution Approach 2:
The patent dynamically changes the dewatering parameters (vacuum pressure, forming bar pressure) based on measured moisture content to optimize the dry content differential between layers, transforming a static process into a dynamically adjustable one that maintains optimal bonding conditions
2Device complexity
If experience-based manual setting of process parameters is used, then the device complexity is reduced, but the manufacturing precision of ply strength deteriorates
Solution Approach 1:
The control system performs self-adjustment by automatically measuring moisture content and modifying dewatering parameters without operator intervention, making the system self-regulating and eliminating dependence on operator experience while maintaining high precision
3Manufacturing precision
If automatic control of dry content is implemented, then the manufacturing precision of ply strength is improved, but the device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The control device serves multiple functions: it receives signals from moisture sensors, processes the data, determines the dry content of each layer, compares it with target values, and controls the dewatering elements, consolidating multiple control tasks into a single multi-functional unit that minimizes additional complexity
4Adaptability or versatility
If basis weight variations are accommodated in multi-layer cardboard production, then the adaptability of the machine is improved, but the ease of operation deteriorates due to increased difficulty in setting process parameters
Solution Approach 1:
The system transitions from static, experience-based parameter setting to dynamic automatic control that continuously adapts to basis weight variations by measuring actual moisture content and adjusting dewatering parameters in real-time, making the system responsive to changing conditions without requiring operator expertise
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 consistently enhances layer strength by maintaining a controlled dry content differential, reducing the risk of delamination and web compression, thereby improving the quality of multi-layer cardboard products.
Implementation Method 1
a first sensor device (34) which measures a first measured value for the dry content of the first fibrous web layer (L1) and a second sensor device (36) which measures a second measured value for the dry content of the second fibrous web layer (L2)
Implementation Method 2
controllable dewatering elements like vacuum suckers to maintain a specific dry content differential between layers
Data Source
Figure 1~2
AI summary
The present invention relates to a forming section (10) for a machine for producing a multilayer fibrous web (FB), in particular a multilayer cardboard web, comprising: at least a first headbox (12) and a first continuously rotating forming screen (14) associated with the first headbox (12) for forming a first fibrous web layer (L1), a second headbox (22) and a second continuously rotating forming screen (24) associated with the second headbox (22) for forming a second fibrous web layer (L2), and a couching device (30) for couching the first fibrous web layer (L1) with the second fibrous web layer (L2).Furthermore, the forming section (10) comprises: a first sensor device (34) configured to measure the dryness of the first fiber web layer (L1) before couching, a second sensor device (36) configured to measure the dryness of the second fiber web layer (L2) before couching, and a control device (32) configured to receive the measured values from the first sensor device (34) and the second sensor device (36) and, based on the received measured values, to adjust the dryness of the first fiber web layer (L1) and/or the dryness of the second fiber web layer (L2) before couching.