Dual-Stage Screening for Sheet Manufacturing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Sheet manufacturing apparatuses using dry methods face challenges with defibration efficiency, resulting in varying fiber lengths and the inclusion of undefibrated pieces, which affect the binding strength and texture of the final product, leading to decreased paper quality.

Innovation Solution

A sheet manufacturing apparatus with a dual-screening system using sieves with different opening sizes to separate defibrated materials by fiber length, where the first screening unit with smaller openings moves faster than the second, ensuring only fibers within a predetermined range are used for sheet formation, while undefibrated pieces are returned for redefibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single screening unit is used to separate defibrated material, then the process is simple, but fibers of inconsistent lengths are mixed, decreasing sheet strength

Engineering Contradiction:

Improvescreening processVSAvoidsheet strength

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The screening process is divided into two sequential stages: first screening with larger openings to remove undefibrated pieces, and second screening with smaller openings to remove short fibers. This segmentation allows each screening unit to perform a specialized function, resulting in fibers of consistent length that produce stronger sheets.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If dry defibration is used to reduce water consumption, then energy is conserved and scale is reduced, but fiber length uniformity deteriorates

Engineering Contradiction:

Improvewater consumptionVSAvoidfiber length uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The first screening unit performs preliminary separation by removing undefibrated pieces before the second screening unit removes short fibers. This preliminary action ensures that only properly defibrated fibers proceed to the next stage, maintaining fiber length uniformity in the dry defibration process.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If short fibers are included in sheet material, then more material is available for production, but binding strength decreases

Engineering Contradiction:

Improveproduction volumeVSAvoidbinding strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The second screening unit extracts and removes short fibers from the defibrated material through its smaller openings. By taking out the harmful short fibers that would otherwise be incorporated into the sheet, the process ensures that only fibers of appropriate length contribute to production, maintaining binding strength.

Inventive Principle:

Principle #2Taking out (Extraction)

4Loss of substance

If undefibrated pieces are included in sheet material, then material utilization is maximized, but sheet texture deteriorates

Engineering Contradiction:

Improvematerial utilizationVSAvoidsheet texture

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

The first screening unit performs preliminary removal of undefibrated pieces through its larger openings before the material proceeds to second screening. This preliminary action ensures that only properly defibrated fibers are processed further, maintaining uniform sheet texture while minimizing material loss.

Inventive Principle:

Principle #10Preliminary action

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 approach enhances the strength and texture of the manufactured sheet by eliminating short fibers and undefibrated pieces, improving binding strength and uniformity, and allowing for the reuse of residual materials, thus optimizing the paper production process.

Implementation Method 1

a first screening unit to which a plurality of first openings are provided and a second screening unit to which a plurality of second openings larger than the first openings are provided, the defibrated material being screened by the first screening unit and the second screening unit

Methodology Applied

Scientific EffectMechanical screening: Filter (physical)

Implementation Method 2

Methodology Applied

Scientific EffectMechanical screening: Filter (physical)

Data Source

PatentUS9174243B2Sheet manufacturing apparatus and method for manufacturing sheet

Publication Date: 2015.11.03 SEIKO EPSON CORP

AI summary

A sheet manufacturing apparatus includes comprises a screening unit configured to screen a defibrated material obtained by defibration treatment, and a sheet forming unit configured to form a sheet with the defibrated material screened with the screening unit. The screening unit has a first screening unit to which a plurality of first openings are provided and a second screening unit to which a plurality of second openings larger than the first openings are provided, and the defibrated material is screened by the first screening unit and the second screening unit. The defibrated material is screened at one of either the first screening unit or the second screening unit and thereafter screened at the other, and the sheet forming unit forms the sheet with the defibrated material that does not pass through the first openings and does pass through the second openings.