Inclined Screen Former Headbox Gap Repositioning
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Solution Overview
Problem
Conventional inclined wire formers face challenges in producing high-quality long-fiber paper or wet-laid nonwoven webs, such as battery separator paper webs, aramid paper webs, or capacitor paper webs, due to issues like fiber agglomerations, non-uniform thickness, and pinholes, which are exacerbated by backflow of fiber suspension along the inclined wire section.
Innovation Solution
The inclined wire former is modified by arranging the outlet gap of the headbox above the substantially horizontally extending section of the wire, preventing backflow and ensuring uniform application of the fiber suspension. Additionally, dewatering elements and suction fixation devices are strategically placed to maintain a consistent waterline and enhance dewatering efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the outlet gap is arranged on the inclined section of the wire, then the fiber suspension can be applied to the wire, but backflow of fiber suspension occurs along the inclined wire section
Solution Approach 1:
The outlet gap is inverted from its conventional position on the inclined section to a position above the horizontal section of the wire. This inversion prevents backflow by ensuring that gravity acts to keep the fiber suspension on the wire rather than allowing it to flow back along the inclined section.
Solution Approach 2:
The outlet gap is repositioned in the vertical dimension, extending the front wall of the headbox beyond the deflection point so that the outlet gap is located above the horizontal wire section rather than on the inclined section. This dimensional change eliminates the backflow path.
2Productivity
If dewatering elements are arranged only on the inclined section, then dewatering occurs in the inclined region, but dewatering is insufficient in the horizontal section where fiber suspension is applied
Solution Approach 1:
Dewatering elements are positioned in advance on the horizontal section of the wire, extending beyond the deflection point. This preliminary positioning ensures that dewatering occurs immediately where fiber suspension is applied, preventing excessive moisture accumulation and ensuring uniform web thickness from the start of the forming process.
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 configuration significantly improves the quality of the fibrous web by preventing backflow, ensuring uniform thickness, and enhancing dewatering efficiency, thereby meeting the high quality requirements of specialized paper webs.
Implementation Method 1
at least one dewatering element (40) is arranged on the bottom side for dewatering the at least a portion of the at least one fibrous suspension applied to the wire
Implementation Method 2
a portion of the fiber suspension exiting the outlet gap flows back along the inclined section of the wire due to gravity
Implementation Method 3
a suction fixation device is arranged beneath the essentially horizontally extending screen section, by means of which the position of the waterline of the at least one fiber suspension on the essentially horizontally extending screen section can be fixed
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to an inclined screen former (10) for producing a fibrous web, in particular a long-fiber paper or wet-woven web, from at least one fibrous suspension, comprising a screen (30) which runs over a circumferential region of a breast roll (32) and subsequently runs at least partially at an angle to the horizontal in the screen running direction before being deflected at a deflection point into a substantially horizontal direction, wherein in this inclined section of the screen (30) at least one headbox (20) applies at least a portion of the at least one fibrous suspension to the top of the screen (30), and at least one dewatering element (40) is arranged on the underside for dewatering the at least portion of the at least one fibrous suspension applied to the screen (30), wherein the headbox (20) comprises a front wall (22),which together with the sieve (30) defines a discharge gap (24) for the at least one fibrous suspension, wherein the front wall (22) of the headbox (20) extends in the sieve direction beyond the deflection point of the sieve (30), so that the discharge gap (24) is arranged above the substantially horizontally extending section of the sieve (30).