Vortex Chamber Particle Rounding for Rare Earth Magnets

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Solution Overview

Problem

Conventional grinding processes for rare earth magnetic powders produce particles with sharp corners and edges, leading to reduced magnetic values and energy densities in permanent magnets.

Innovation Solution

A grinding device with a vortex chamber that uses fluid jets blown in from different points to create a turbulent, circular flow, where particles are suspended and ground without shattering, by employing a guide ring with blowing openings oriented in opposite directions to break or abrade edges, creating a zone of strong shear for effective rounding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional grinding methods (fluidized-bed jet mills) are used to grind rare earth magnetic powders, then the particles are ground to fine sizes, but the particles develop sharp corners and edges which reduce magnetic properties and energy density

Engineering Contradiction:
Improveparticle shape quality (roundness)VSAvoidmagnetic properties and energy density
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses a fluidized bed with upward fluid flow to suspend and round particles. Gas or liquid fluid jets are injected through a distributor plate to create turbulent flow that rounds particle corners and edges while maintaining spherical shape, eliminating the sharp edges produced by conventional jet mills.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent employs mechanical vibration of the fluidized bed or container to enhance particle rounding. Vibration increases particle collisions and movement, accelerating the rounding process and improving shape uniformity while preventing aggregation and maintaining magnetic properties.

Inventive Principle:
Principle #18Mechanical vibration

2Productivity

If higher kinetic energy is used in traditional jet mills to achieve grinding, then particle size is reduced, but particles shatter and develop more sharp edges rather than rounding

Engineering Contradiction:
Improvegrinding efficiencyVSAvoidparticle roundness
Core Design Contradiction:
ProductivityVSShape

Solution Approach 1:

The patent changes the kinetic energy parameter from high to low range. Instead of using high-velocity jets that cause shattering, low-velocity fluid jets create gentle tumbling and rolling motions that progressively round particles without fragmentation, achieving both productivity and shape quality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses controlled fluidization with optimized gas or liquid flow rates to create the appropriate low-energy turbulent environment. The fluid velocity is carefully regulated to suspend particles and induce rounding through controlled collisions, preventing the high-energy shattering that occurs in conventional jet mills.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 device effectively rounds particles, reducing sharp edges and corners, thereby improving magnetic properties and energy densities of the resulting magnets without causing them to shatter, achieving a grinding effect with lower kinetic energy than traditional jet mills.

Implementation Method 1

The fluid flow moving within the vortex chamber is generated by fluid jets that are injected into the vortex chamber at different locations using a blowing device... The injection of the fluid jets preferably creates a turbulent, circular flow in the vortex chamber

Methodology Applied
Scientific EffectTurbulence: Turbulence

Implementation Method 2

a vortex chamber for treating the particles suspended in a fluid stream... fluid jets that are injected into the vortex chamber... drive a fluid flow that tends to circulate in a first main flow direction around the central axis of the vortex chamber

Methodology Applied
Scientific EffectVortex flow: Vortex Ring

Implementation Method 3

These second blower openings drive a fluid flow that tends to circulate around the center axis of the vortex chamber in a second main flow direction, which is opposite to the first main flow direction... creating a zone of strong shear for effective rounding

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 4

creating a zone of strong shear for effective rounding

Methodology Applied
Scientific EffectShear stress: Shear Stress

Data Source

PatentEP3738673B1Grinding device for rounding particles
Publication Date: 2024.07.31 NETZSCH TROCKENMAHLTECHNIK GMBH
  • EP3738673B1 patent drawingFigure 1~2
  • EP3738673B1 patent drawingFigure 3
  • EP3738673B1 patent drawingFigure 4

AI summary

The invention relates to a grinding device for rounding particles. The grinding device comprises a swirl chamber for treating the particles suspended in a fluid stream. The invention further relates to a corresponding method and, optionally, the associated use.