Grooved Deflection Roller and Suction Former for Stable Web Pickup
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Solution Overview
Problem
Existing paper machine formers fail to completely prevent fiber web floatation and have insufficient dry content at the pickup point, leading to increased load on the press section.
Innovation Solution
A former design with a non-vacuum-controlled deflection roller featuring spirally extending grooves on its surface and high-vacuum suction elements positioned before and after the pickup point, enhancing air intake and web stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a deflection roller with grooves is used to prevent fiber web floatation, then the fiber web running properties improve, but the dry content at the pickup point remains insufficient
Solution Approach 1:
The suction system is segmented into multiple independent suction elements distributed along the forming wire, with each element having specific openings for targeted air suction. This segmentation allows precise control of air removal in different zones without compromising web stability.
Solution Approach 2:
A vacuum system with multiple suction elements is implemented to remove air from the run-up gap between the forming wire and deflection roller. The suction elements create negative pressure zones that actively draw air out, preventing floatation while enhancing dewatering capacity before the pickup point.
2Stability of the object's composition
If vacuum is applied to the deflection roller to improve web stability, then floatation is reduced, but energy consumption increases
Solution Approach 1:
Vacuum is applied locally only at specific suction elements positioned where air accumulation occurs in the run-up gap, rather than applying vacuum to the entire deflection roller. This localized approach maintains web stability where needed while minimizing unnecessary energy consumption in other areas.
Solution Approach 2:
The suction elements act as intermediaries between the vacuum source and the air trapped in the run-up gap. They selectively remove air without requiring the deflection roller itself to be vacuumed, thus reducing energy consumption while maintaining web stability.
3Quantity of substance
If high vacuum suction is applied to increase dry content, then the load on the press section is reduced, but the complexity of the suction system increases
Solution Approach 1:
The suction system is divided into multiple independent suction elements with specific opening patterns, allowing targeted air removal in different zones. This segmentation achieves high dry content through distributed suction while keeping each individual element relatively simple in design.
Solution Approach 2:
The suction elements incorporate openings of specific sizes and patterns that function as porous structures, allowing selective air passage while maintaining structural simplicity. This approach achieves effective dewatering without complex mechanical components.
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
Improves fiber web running properties and reduces load on the press section by preventing floatation and increasing dry content, especially at high speeds and basis weights.
Implementation Method 1
a suction element with openings facing the forming wire is arranged within the loop immediately before the pickup point and immediately after the deflecting roller
Implementation Method 2
The spiral shape of the at least one groove improves the absorption and removal of air that is introduced into the run-up gap between the forming screen and the deflection roller by the air boundary layer formed on the inside of the forming screen
Data Source
Figure 1
Figure 2~4b
AI summary
The invention relates to a former for a paper machine for producing a fibrous material web (1), in particular a paper, card, tissue or packaging paper web, comprising a forming fabric (2) which forms a loop and on which the fibrous material web (1) lies, the forming fabric and fibrous material web being guided together via a deflection roller (3) inside the loop to a pickup point (4) at which the fibrous material web (1) is taken from the forming fabric (2) by a clothing (6), a suctioned suction element (7) with openings (9) facing the forming fabric (2) being situated inside the loop directly before the pickup point (4) and directly after the deflection roller (3). The invention is characterised in that the deflection roller (3) is not suctioned and has at least one spiral groove (10) in the circumferential direction on the surface, and in that the suction element (7) is preferably in the form of a high-vacuum suction device.