Cross-hatch Screen Plate for Pulper Defibering
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Solution Overview
Problem
Existing screen plates in pulpers have reduced available screening surface area due to surface projections like strips and bars, which also require high heat processing, leading to warping and increased manufacturing costs, and inserts extending above the base plate cause material accumulation and limited shearing action.
Innovation Solution
A screen plate with a cross-hatched pattern of intersecting grooves and lands, each with through-holes, providing maximum edge impact surfaces and defibering edges regardless of rotor direction, maintaining open area and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strips and bars are applied on the screen plate to provide edge impacting surfaces, then the shearing action on fiber suspension is improved, but the available screening surface area is reduced and manufacturing complexity increases due to welding requirements
Solution Approach 1:
The screen plate surface is segmented into a cross-hatch pattern of intersecting grooves that create multiple small lands and edges throughout the surface. This segmentation provides numerous edge impacting surfaces for fiber processing while maintaining open screening area, as the grooves themselves define the functional edges without requiring separate protruding elements.
Solution Approach 2:
The invention extracts the edge impacting function from separate protruding elements (strips and bars) and integrates it directly into the base plate geometry through grooves. By removing material to create grooves rather than adding material to create projections, the screening surface area is preserved while the edge impacting functionality is maintained.
2Productivity
If strips and bars are welded to the screen plate to create surface projections, then edge impacting capability is improved, but warping and surface distortion occur requiring additional work processes
Solution Approach 1:
Instead of adding material through welding to create surface projections, the invention removes material to form grooves in the base plate. This extraction approach eliminates the welding process entirely, preventing the heat-induced warping and surface distortion that would otherwise require additional corrective work processes.
Solution Approach 2:
The groove-based edge impacting surfaces are integrated directly into the base plate structure, eliminating the need for separate weldable components. This integration reduces manufacturing complexity and eliminates the quality issues associated with welding operations.
3Productivity
If inserts extend above the base plate to provide shearing action, then fiber suspension processing is improved, but material accumulates in areas between inserts and manufacturing time increases
Solution Approach 1:
The invention extracts the edge impacting function from separate inserts and integrates it into the base plate through grooves. By removing material to create grooves rather than adding inserts, the manufacturing process is simplified and accelerated, eliminating the time-consuming metallurgical bonding step while preventing material accumulation in inter-element spaces.
Solution Approach 2:
The groove-based edges are merged directly with the base plate structure, creating a unified component rather than assembling separate parts. This integration eliminates the need for inserts and their associated bonding processes, reducing manufacturing time and eliminating void spaces where material could accumulate.
4Strength
If inserts are metallurgically bonded to the base plate, then structural integrity is improved, but manufacturing costs increase
Solution Approach 1:
The invention extracts the edge impacting function from separate inserts and integrates it into the base plate through grooves. This eliminates the need for metallurgical bonding of separate components, reducing manufacturing costs while maintaining structural integrity through the monolithic groove structure.
Solution Approach 2:
The groove-based edges are formed as an integral part of the base plate, eliminating the need for expensive separate components and their associated bonding processes. This integrated approach reduces manufacturing costs while providing sufficient structural integrity for the application.
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 cross-hatch pattern maximizes edge impact and defibering efficiency without reducing the screening area, reducing defibering times and energy consumption while minimizing manufacturing costs and material accumulation.
Implementation Method 1
The rotor causes the source of fiber to rotate past the screen plate
Implementation Method 2
the raised blocks defined by the lands each have side edges, which depending upon the rotational direction of the rotor, provide maximum edge impacting surfaces
Data Source
AI summary
A screening machine for a fiber suspension includes a vessel; a rotor disposed within the vessel; and a screen plate positioned in stationary opposition to the rotor. The screen plate includes a plurality of substantially parallel first grooves extending in a first direction and a plurality of substantially parallel second grooves extending in a second direction. The first grooves intersect with the second grooves. The first grooves and the second grooves conjunctively define a plurality of lands and depressions. A plurality of the lands and a plurality of the depressions include a through-hole extending through the screen plate.