Permanent Magnet Heating Cycle for Narrow-Pitch Multipolar Magnetization
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Solution Overview
Problem
Existing methods for magnetizing Nd—Fe—B-based sintered magnets with high coercive force are inadequate for achieving high magnetization characteristics, particularly in multipolar magnetization, leading to reduced performance in high-temperature environments and limited coil winding options.
Innovation Solution
A manufacturing method involving a magnetizer with a field magnet unit and heating unit to heat the magnet to above its Curie point and then cool it below, applying a magnetization magnetic field using permanent magnets with controlled pole pitch, ensuring uniform heating and magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pulse magnetization is used on hot-worked magnets with high coercive force, then magnetization process is simplified, but high magnetization characteristics cannot be achieved due to limitations in coercive force and heat resistance
Solution Approach 1:
The patent changes the temperature parameter during magnetization, specifically heating the magnet to a temperature between the Curie points of the magnet and the permanent magnets (50°C to 200°C). This temperature parameter change reduces the coercive force temporarily, allowing successful multipolar magnetization while maintaining the benefits of simplified pulse magnetization process.
Solution Approach 2:
The patent employs periodic heating and cooling cycles during the magnetization process. The magnet is heated to reduce coercive force for magnetization, then cooled to restore high coercive force and heat resistance, creating a periodic cycle that enables both simplified processing and high performance.
2Measurement precision
If multipolar magnetization is attempted with narrow magnetization pitch, then resolution is improved, but the number of coil turns and coil diameter are limited preventing sufficient magnetization field strength
Solution Approach 1:
The patent changes the temperature parameter to reduce coercive force during magnetization, enabling the use of permanent magnets with narrow pole pitch (0.5mm to 2.0mm) to achieve high resolution multipolar magnetization. The reduced coercive force at elevated temperature allows sufficient magnetization field strength to be applied despite the narrow pitch constraints.
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 method achieves high magnetization characteristics in rare earth iron-based magnets with magnetic anisotropy, even with narrow pole pitches, enhancing performance in motors and sensors.
Implementation Method 1
the to-be-magnetized object is heated by the heating unit to a temperature equal to or higher than a Curie point of the to-be-magnetized object
Implementation Method 2
a magnetization magnetic field is applied to the to-be-magnetized object by the permanent magnets for magnetization
Data Source
AI summary
A manufacturing method for a permanent magnet includes a magnetization step of magnetizing a to-be-magnetized object by a magnetizer including a field magnet unit having a plurality of permanent magnets for magnetization configured to generate a magnetic field on the to-be-magnetized object arranged at equal intervals and a heating unit having a heating surface opposing the to-be-magnetized object in an axial direction of the to-be-magnetized object and configured to heat the to-be-magnetized object. In the magnetization step, the to-be-magnetized object is disposed on the field magnet unit, the to-be-magnetized object is heated by the heating unit to a temperature equal to or higher than a Curie point of the to-be-magnetized object and lower than the Curie point of the permanent magnets for magnetization, and then the temperature is lowered to a temperature lower than the Curie point of the to-be-magnetized object, and a magnetization magnetic field is applied to the to-be-magnetized object by the permanent magnets for magnetization.