Heat Conductive Metal Belt for Web Transfer in Paper Machines
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Solution Overview
Problem
The transfer of webs from a press section to a dryer section in paper or board making machines often results in web drawing or sticking due to the web's low strength and high water content, which existing technologies fail to address effectively.
Innovation Solution
A belt assembly comprising a heat conductive, fluid-impermeable metal belt forming an endless loop with a stretcher/guiding roll and proportional position control, along with heating and cleaning mechanisms, to accurately position and dry the web before transferring it to the dryer section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fabric or wire loop is used to transfer the web from press section to dryer section, then the web can be transferred, but web drawing and sticking occur due to low web strength and high water content
Solution Approach 1:
The patent changes the material parameter of the transfer belt from fabric/wire to metal, which fundamentally alters the friction characteristics and mechanical properties. The metal belt provides higher friction coefficient and better dimensional stability, preventing web drawing and sticking while maintaining reliable transfer of high-moisture webs
Solution Approach 2:
The metal belt is equipped with composite heating devices (steam chambers, heating elements) that create a thermal field. This composite system of metal belt plus thermal treatment provides both mechanical transfer function and web strengthening through preheating, eliminating the harmful effects of web drawing and sticking
2Productivity
If the web is transferred with high water content from press section, then transfer can occur, but web strength is insufficient causing drawing problems
Solution Approach 1:
The patent applies preliminary heating action to the web on the metal belt before the web enters the dryer section. The heating devices (steam chambers, heating elements) preheat the web surface and increase web strength in advance, preventing drawing problems during transfer while maintaining high productivity
Solution Approach 2:
The metal belt material changes the thermal and friction parameters of the transfer system. Combined with active heating, this creates optimal conditions for transferring high-moisture webs without compromising web strength or transfer efficiency
3Quantity of substance
If a metal belt with heating devices is used, then web dry content increases by 2-15%, but device complexity increases
Solution Approach 1:
The metal belt serves multiple functions simultaneously: it acts as the transfer medium, provides structural support, and serves as the heating surface for web drying. This multi-functionality eliminates the need for separate heating apparatus, reducing overall device complexity while achieving 2-15% increase in web dry content
Solution Approach 2:
The heating devices (steam chambers, heating elements) are merged with the metal belt structure itself. The belt becomes an integrated thermal processing unit, combining transfer and drying functions in one component, thereby simplifying the overall system despite the added heating capability
4Measurement precision
If proportional position control is implemented to control metal belt position with respect to stretcher/guiding roll, then position accuracy is improved, but device complexity increases
Solution Approach 1:
The proportional position control system uses feedback from position sensors to continuously monitor and adjust the metal belt position relative to the stretcher/guiding roll. This feedback mechanism achieves high position accuracy (±2 mm control margin) while using standard control technologies, balancing precision with acceptable system complexity
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
The solution ensures a smoother transfer with reduced tearing, achieving a 2-15% higher dry content of the web upon arrival at the dryer section, minimizing web sticking and drawing, and allowing for various treatments during transfer.
Implementation Method 1
A heat conductive metal belt that forms an endless loop... goes over the first press roll and the stretcher/guiding roll
Implementation Method 2
The transfer of the web takes place due to the suction effect of the suction roll 103
Data Source
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AI summary
A belt assembly for moving a web from a press section (1) of a paper- or board-making machine to a dryer section (3) of the machine, comprises a combination of a first press roll (11) adapted to be arranged at the press section (1), and a stretcher/guiding roll (51) which is arranged between the press section (1) and the dryer section (3). A heat conductive metal belt (5) that forms an endless loop and that is impervious to fluids goes over the first press roll (11) and the stretcher/guiding roll (51), so as to take over a web at the press section (1) and to move the web to the dryer section (3). A guide roll proportional position control is adapted to control the position of the metal belt (5) between the edges of the stretcher/guiding roll (51).