Hard Sizing Roll with Soft Application Element for Uniform Coating
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Solution Overview
Problem
Existing fiber web sizing technologies face issues with uneven sizing agent layers due to hard-surfaced rolls, which can lead to defects in the fiber web surface and increased wear between surfaces, especially when using soft-coated rolls with hard application elements.
Innovation Solution
A sizer featuring at least one hard-surfaced sizing roll paired with a soft-surfaced application element, where the application element's hardness is significantly lower than the sizing roll's, allowing the soft surface to yield and form a smooth, even sizing agent layer without causing defects and reducing surface wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If soft-surfaced rolls with hard application elements are used, then the sizing agent layer can be applied, but surface wear increases and manufacturing precision deteriorates due to uneven sizing agent layers
Solution Approach 1:
The patent changes the hardness parameter of the sizing roll surface to be harder than the application element, reversing the conventional soft-surfaced roll approach. This parameter reversal allows the harder roll surface to maintain its geometry and resist wear while the softer application element deforms to create the necessary nip for uniform sizing agent application.
Solution Approach 2:
The patent inverts the traditional hardness assignment by making the sizing roll harder than the application element, rather than the conventional soft roll with hard application element. This inversion resolves the contradiction by allowing the harder roll to resist wear while the softer application element provides the necessary compliance for uniform sizing.
2Reliability
If hard-surfaced sizing rolls are used, then surface wear is reduced, but manufacturing precision worsens due to inability to form smooth sizing agent layers
Solution Approach 1:
The patent changes the relative hardness parameters between the sizing roll and application element, making the roll harder than the application element. This allows the roll to resist wear while the softer application element deforms to create a smooth, uniform sizing agent layer through proper nip formation.
Solution Approach 2:
The softer application element acts as an intermediary between the hard sizing roll and the sizing agent, absorbing the hardness difference and providing the necessary compliance to create a smooth, defect-free sizing agent layer while the hard roll maintains its structural integrity and wear resistance.
3Manufacturing precision
If soft roll coating is used, then sizing agent layer can be formed, but device complexity increases due to softer material requirements
Solution Approach 1:
The patent changes the hardness parameter assignment, making the sizing roll harder than the application element. This simplifies the material specification requirements by allowing the use of standard hard roll materials (ceramic, metal, or hard polymer) rather than requiring specialized soft roll coatings, while still achieving high-quality sizing agent layer formation.
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 smooth and even sizing agent layer is applied to the fiber web, minimizing defects and reducing surface wear, thereby improving the quality of the finished fiber web while maintaining a functional nip for effective sizing.
Implementation Method 1
loading the application element, it is pressed partially into the soft roll coating and thus, a nip of desired length is formed between the roll and the application element
Implementation Method 2
The smooth rods are smooth surfaced and the dosing is based on hydrodynamic force
Data Source
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Figure 5~6
AI summary
The invention relates to a sizer (10), which comprises at least one hard-surfaced sizing roll (11; 12), application means (22) configured to apply a sizing agent layer (A) onto the surface of the hard-surfaced sizing roll (11), an application element (20) configured to smoothen the sizing agent layer (A) to a smooth sizing agent layer (AS). The application element (20) is a soft-surfaced application element (20) and hardness of the soft-surfaced application element (20) is substantially lower than hardness of the hard-surfaced sizing roll (11).