Coreless Radial Magnet Molding for Micro-Motors

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Solution Overview

Problem

Existing methods for producing radially oriented magnet rings for micro-motors are limited by the need for a mold core, which restricts the inner diameter to greater than 3 mm, and the magnetic particles' tendency to demagnetize after the orientation field disappears, affecting the magnetic performance.

Innovation Solution

A method integrating magnetic and mechanical principles to radially orient anisotropic magnetic particles in a mold cavity without a core, using a quasi-2D oriented magnetic field and staged magnetic fields to maintain alignment, with the relationship W=nD+W0 ensuring a radial orientation degree of at least 90%, and a molding process involving continuous rotation and stress application to prevent demagnetization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a mold core is used to produce radially oriented magnet rings, then the molding process is feasible, but the inner diameter is restricted to greater than 3 mm

Engineering Contradiction:

Improvemolding process feasibilityVSAvoidinner diameter

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The patent removes the mold core from the molding process entirely. By using a mold without a core and applying a specific oriented magnetic field during molding, the method enables production of radially oriented magnets with inner diameters less than 3 mm, which was previously impossible with core-based methods.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical mold core system with a magnetic field-based orientation system. Instead of using a physical core to define the inner diameter and facilitate molding, the invention uses an oriented magnetic field to radially orient magnetic particles during molding, enabling coreless production of miniature magnets.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If the oriented magnetic field is removed after molding, then the magnetic particles can be demolded, but the magnetic particles tend to demagnetize and recover to out-of-order state

Engineering Contradiction:

Improvedemolding capabilityVSAvoidmagnetic performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies a unidirectional magnetic field during the molding process to pre-orient the magnetic particles in the desired radial pattern. This preliminary orientation action ensures that when the oriented magnetic field is removed for demolding, the particles maintain their oriented state due to the structural locking achieved during molding, preventing demagnetization.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The molding process creates a structural framework that cushions and locks the magnetic particles in their oriented positions before the oriented magnetic field is removed. This beforehand structural preparation prevents the particles from recovering to a random out-of-order state after field removal.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If parallel oriented permanent magnetic material tiles are used, then the materials can be easily manufactured, but magnetic field components are generated in non-radial direction causing vibration and noise

Engineering Contradiction:

Improvemanufacturing easeVSAvoidvibration and noise

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the orientation parameter of the magnetic particles from parallel (conventional) to radial orientation. By controlling the magnetic field direction during molding, the magnetic particles are oriented radially, which eliminates non-radial magnetic field components and the associated vibration and noise, while maintaining manufacturing feasibility through the coreless molding process.

Inventive Principle:

Principle #35Parameter changes

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

Enables the production of radially oriented solid cylindrical magnets with inner diameters less than 3 mm, maintaining high magnetic performance and allowing for mass production of miniature magnets with improved magnetic properties.

Implementation Method 1

the easy directions of magnetization of anisotropic magnetic particles in a mold cavity are radially oriented in a quasi-2D oriented magnetic field

Methodology Applied

Scientific EffectMagnetic field orientation: Magnetic Field

Implementation Method 2

radially oriented solid cylindrical magnet... easy directions of magnetization of anisotropic magnetic particles

Methodology Applied

Scientific EffectMagnetization: Magnetism

Data Source

PatentUS11251686B2Radially oriented solid cylindrical magnet and production method and device thereof

Publication Date: 2022.02.15 SHENZHEN RADIMAG TECH CO LTD

AI summary

The present disclosure provides a radially oriented solid cylindrical magnet, a method and device for molding and manufacturing the same, and a rotor and motor component using the same. The radial orientation degree of the solid cylindrical magnet is greater than or equal to 90%. A mold includes no mold core. Magnetic particles in the mold are continuously rotated in a magnetic field during molding, and an oriented magnetic field is applied during molding. The manufactured solid cylindrical magnet can be directly used as a rotor of a micro-motor to replace a conventional rotor with a radially oriented magnet ring, or can be used for producing radially oriented magnet rings with an arbitrary inner diameter, so as to obtain radially oriented magnet rings having an inner diameter less than 3 mm or even less for micro-motors.