Two-Stage Cyclone Classifier for Toner Particle Size Control

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Solution Overview

Problem

Conventional toner production methods result in unstable image quality due to broad particle size distribution and inefficient classification, leading to excessive mixing of fine and coarse powders, which increases production costs and reduces image quality.

Innovation Solution

A cyclone classifier with a dispersion chamber and a classification chamber, featuring a center core with a fine powder discharge pipe and a separator core, enhances swirling velocity and classification accuracy by allowing two-staged classification, reducing the mixing of fine and coarse powders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional mechanical pulverizers with single-stage classification are used, then the pulverizing process is simple, but the particle size distribution is broad with excessive fine powder and coarse powder mixing

Engineering Contradiction:
Improveparticle size distribution sharpnessVSAvoidclassifier structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The classifier is divided into two independent stages: coarse powder classifier and fine powder classifier. Each stage has its own cyclone and classification mechanism, allowing separate optimization of classification parameters for different particle size ranges, thereby achieving sharp particle size distribution without excessive mixing of fine and coarse powder

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from single-stage to two-staged classification, adding a temporal and functional dimension to the classification process. The first stage handles coarse powder removal while the second stage refines fine powder separation, creating a multi-dimensional classification system that achieves superior particle size control

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If single-stage classification is used, then the device complexity is low, but the classification efficiency is poor with excessive mixing of fine and coarse powders

Engineering Contradiction:
Improveclassification efficiencyVSAvoidclassifier structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The classification function is segmented into two distinct operations: coarse powder classification in the first stage and fine powder classification in the second stage. This segmentation allows each classifier to operate at optimal efficiency for its specific particle size range, preventing the mixing problems that occur in single-stage systems

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first-stage classifier acts as an intermediary that removes coarse powder before the material enters the second-stage classifier. This intermediate classification step prevents coarse powder from contaminating the fine powder product while allowing the second stage to focus exclusively on fine powder separation, thereby improving overall classification efficiency

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If closed-circuit pulverization with single-stage classification is used, then the pulverizing process is continuous, but the amount of fine powder mixed into product is large requiring excessive re-pulverization

Engineering Contradiction:
Improveproduct purityVSAvoidpulverization efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The classification system is segmented into two stages with the first stage specifically designed to remove coarse powder that would otherwise require re-pulverization. By separating coarse and fine powder classification into distinct stages, the system achieves high product purity while maintaining continuous pulverization efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first-stage classifier performs preliminary removal of coarse powder before the material enters the fine powder classification stage. This preliminary action prevents coarse powder from being mixed into the final product, eliminating the need for excessive re-pulverization cycles and maintaining both product purity and production efficiency

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

The solution achieves a sharp particle size distribution, improving image stability, reducing production costs, and enhancing the efficiency of toner production by minimizing the amount of fine and coarse powder mixed, resulting in stable charge amounts and improved image quality.

Implementation Method 1

a cyclone classifier including a dispersion chamber (2-2) equipped with a center core (2-5) and used for dispersing the powder, and a classification chamber (2-3) equipped with a separator core (2-8)... the swirling velocity of the pulverized material is further increased

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the center core (2-5) has at its center a fine powder discharge pipe (2-5a)... the swirling velocity of the pulverized material is further increased by suction of the discharge pipe (2-5a)

Methodology Applied
Scientific EffectVortex flow: Vortex Ring

Data Source

PatentEP2150359B1Pulverizing and coarse powder classifying apparatus and fine powder classifying apparatus
Publication Date: 2015.05.06 RICOH CO LTD
  • EP2150359B1 patent drawingFigure 1
  • EP2150359B1 patent drawingFigure 2~3
  • EP2150359B1 patent drawingFigure 4

AI summary

A pulverizing and coarse powder classifying apparatus including: a mechanical pulverizer that pulverizes a powder raw material, a cyclone that collects pulverized powder, and a coarse powder classifier that separates coarse powder from the collected powder, wherein the coarse powder classifier is a cyclone classifier including a dispersion chamber equipped with a center core and used for dispersing the powder, and a classification chamber equipped with a separator core, and wherein the center core has at its center a fine powder discharge pipe.