Magnetic Field Orientation of Nd-Fe-B Powder Using Vibration
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Solution Overview
Problem
The existing compression molding methods for manufacturing Nd—Fe—B sintered magnets face challenges in achieving high orientation due to friction among powder particles and between particles and the mold, leading to poor magnetic properties and orientation disorders.
Innovation Solution
The method involves filling a chamber with powder polarized in a magnetic or electric field, agitating it to align crystal fractures, and then compression molding in the same field to create a high-density, oriented body with reduced density fluctuations, using a uniaxial or isostatic pressurizing type of compression molding machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If compression molding is performed using a uniaxial pressurizing type of compression molding machine, then the molding process can be simplified, but high orientation cannot be obtained due to friction among particles and between particles and the mold wall surface
Solution Approach 1:
The patent applies vibration to the lower punch during compression molding to reduce friction among alloy raw meal powder particles and between particles and the mold wall surface. The vibration converts static friction to dynamic friction, improving particle flowability and enabling high orientation during magnetic field charging, thereby resolving the contradiction between simplified molding process and manufacturing precision
Solution Approach 2:
The patent introduces dynamic vibration to the compression molding process, making the previously static molding system dynamic. This allows the lower punch to vibrate in the pressurizing direction during magnetic field orientation, enabling particles to rearrange themselves for high orientation while maintaining process simplicity
2Ease of operation
If vibration is applied to one of the punches during magnetic field orientation, then friction among particles is reduced and flowability is improved, but the positional relationship among particles hardly changes from the initial filled state
Solution Approach 1:
The patent combines vibration of the lower punch with magnetic field charging in a coordinated manner. The vibration frequency and amplitude are optimized to work synergistically with the magnetic field strength, allowing particles to both flow easily and arrange themselves in the magnetic field direction, thereby achieving both improved flowability and particle arrangement
3Device complexity
If alloy raw meal powder is filled into the cavity and oriented in magnetic field without agitation, then the process is simple, but crystal fractures of adjoining particles do not match and clearance remains among particles
Solution Approach 1:
The patent applies vibration to the lower punch during the filling and orientation process, which causes alloy raw meal powder particles to move and agitate. This vibration enables crystal fractures of adjoining particles to match and bond together, eliminating clearance among particles and achieving high orientation without requiring complex agitation mechanisms
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 results in a high-oriented, high-density molded body with improved magnetic properties and reduced occurrence of cracks and splits, enabling the production of permanent magnets with enhanced magnetic performance.
Implementation Method 1
filling a filling chamber with powder that is polarized in magnetic field or electric field
Implementation Method 2
filling a filling chamber with powder that is polarized in magnetic field or electric field
Implementation Method 3
orienting, while agitating, the powder in magnetic field or electric field
Data Source
AI summary
There is provided a method of manufacturing a permanent magnet having extremely high orientation by arranging such that the crystal fractures of alloy raw meal powder having more equal crystal orientational relationship are combined in magnetic field. In this invention, alloy raw meal powder is filled into a cavity and, while agitating the alloy raw meal powder inside the cavity, is oriented in the magnetic field. This oriented body is then compression molded in the magnetic field into a predetermined shape.