Refiner Plate Bar Leading Edge Angle for Fiber Strength
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Solution Overview
Problem
Conventional refiner plates with sharp leading edges cause shearing of fibrous materials during the comminution process, leading to broken fibers and reduced pulp strength, as the sharp edges violently impact the material during rotation, resulting in undesirable force spikes that damage the fibers.
Innovation Solution
The use of refiner plates with dull leading edges and sloped leading faces, having a leading edge angle between 150 degrees and 175 degrees, reduces the impact forces and minimizes shearing by applying gradual compressive pressure, thereby maximizing fiber strength through controlled compression refining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional refiner plates with sharp leading edges are used, then the fibrous material is effectively sheared and separated, but the fibers are damaged and pulp strength is reduced
Solution Approach 1:
The patent changes the geometric parameters of the bar leading edge from sharp (75-100 degrees) to dull (150-175 degrees). This parameter change transforms the interaction mechanism from violent shearing to gradual compression, separating fibers without damaging them, thus maintaining both productivity and fiber strength
Solution Approach 2:
Instead of using sharp edges to cut and shear fibers directly, the patent inverts the approach by using dull edges that compress and gradually separate fibers. This inverted mechanism achieves fiber separation through compression rather than shearing, preserving fiber integrity while maintaining separation efficiency
2Ease of operation
If sharp leading edges are used on bars, then material flow is managed effectively, but force spikes occur that shear and damage the fibrous material
Solution Approach 1:
The dull leading edge design acts as a cushioning element that gradually introduces compressive force to the fibrous material before it enters the refining zone. This beforehand cushioning prevents sudden force spikes by distributing the loading over a longer time period, eliminating violent shearing while maintaining material flow control
3Quantity of substance
If conventional bar geometry with steep leading faces is used, then grooves are wide and allow large material flow, but shearing of fibrous material occurs
Solution Approach 1:
The patent changes the leading face angle parameter from steep (nearly perpendicular) to shallow (150-175 degrees). This parameter change modifies the interaction between bars and fibrous material from impact-based shearing to compression-based separation, eliminating harmful shearing while maintaining adequate material flow volume through the grooves
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 design minimizes the shearing of fibers, enhances the strength of the refined fibers, and ensures a smoother flow of fibrous material through the refining gap, reducing the occurrence of force spikes and promoting efficient fiber separation without damaging the material.
Implementation Method 1
The bars apply forces, such as compression pulses and impact forces, to the material. These forces tend to be greatest when the bars on the opposite plates cross over each other. The forces applied to the fibrous material act on the network of fibers in the material to separate individual fibers from the network and further develop these fibers.
Implementation Method 2
The bars typically include a sharp leading edge along a forward facing top edge of the bar. The conventional sharp leading edge angles of the bars are believed to promote shearing of the fibrous material passing over the bars. The shear impacts of the fibrous material against the bar are a biproduct of the crossing of the bars.
Implementation Method 3
The fibrous material flows in the gap between the plates and, in doing so, moves across the bars on the facing surfaces of the plates. The fibrous material, steam, water and other material flow through the grooves and over the bars as the material moves radially outward between the plates.
Data Source
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AI summary
A refiner plate for a mechanical refining system, the plate including a refining surface including bars (54, 86, 92, 102) and grooves (56, 104), wherein the bars (54, 86, 92, 102) have a leading edge (60, 96, 108) defined by an interior angle of between 140 degrees and 175 degrees.