Magnetizing Small-Diameter Multi-Poled Ring Magnets
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Solution Overview
Problem
Existing methods for magnetizing small-diameter, multi-poled ring-like permanent magnets in stepping motors fail to achieve sufficient magnetization characteristics, particularly with narrow magnetization pitches, resulting in low average surface magnetic flux density and high variation between peak values.
Innovation Solution
A method involving the application of a magnetizing magnetic field by permanent magnets while cooling the object from its Curie point or above to below the Curie point, using a magnetizing device with a structure that includes grooves for inserting magnetizing permanent magnets with a higher Curie point than the object, to ensure consistent and high magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a coil-energizing magnetizing device is used with narrow magnetization pitch, then the magnetization pitch can be reduced, but the allowable current becomes limited and sufficient magnetization characteristic cannot be obtained
Solution Approach 1:
The invention changes the temperature parameter of the object to be magnetized, heating it to the Curie point or above where magnetic permeability increases, thereby enabling sufficient magnetization with lower current density. This allows narrow magnetization pitch to be achieved without sacrificing magnetization characteristic.
Solution Approach 2:
The invention introduces a magnetic yoke as an intermediary component that concentrates and guides the magnetic flux. The yoke with its high permeability (especially when heated) acts as a mediator to deliver stronger magnetic field to the object, overcoming the current limitation imposed by narrow conductor width.
2Manufacturing precision
If permanent magnets are arranged radially to increase pole count, then multi-poled magnetization can be achieved, but magnetization falls short and variation in surface magnetic flux density becomes large for small pitch structures
Solution Approach 1:
By heating the object to the Curie point where magnetic permeability peaks, the invention enables more uniform and complete magnetization across all poles. The high permeability state allows the magnetic field to penetrate evenly, reducing variation in surface magnetic flux density and achieving consistent multi-poled magnetization.
Solution Approach 2:
The invention uses periodic pulse current discharge to magnetize multiple poles sequentially. By controlling the timing and sequence of pulse discharge to each coil group, uniform magnetization across all poles is achieved, reducing variation in surface magnetic flux density.
3Volume of moving object
If the diameter of ring-like permanent magnets is reduced, then miniaturization is achieved, but the magnetization pitch becomes narrower and conductor thickness is limited
Solution Approach 1:
Heating the object to the Curie point dramatically increases magnetic permeability, which compensates for the reduced conductor cross-section area. This allows thin conductors in miniaturized motors to still generate sufficient magnetizing force, enabling further miniaturization without sacrificing magnetization capability.
4Force
If high coercivity materials like Nd-based bonded magnets are used, then magnetic strength is improved, but magnetization becomes more difficult and existing methods fail to achieve sufficient magnetization
Solution Approach 1:
By heating the high coercivity material to the Curie point, the invention temporarily transforms its magnetic properties - the permeability increases dramatically and coercivity decreases. This allows easy magnetization during the heated state, and upon cooling, the material retains the desired high coercivity and strong magnetic force, solving the contradiction between magnetic strength and ease of magnetization.
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 achieves high magnetization characteristics with reduced variation in surface magnetic flux density, effectively magnetizing small-diameter multi-poled permanent magnets with improved magnetic force and quality, even for materials with high coercivity like Nd-based bonded magnets.
Implementation Method 1
a magnetizing magnetic field applying means to be adjacent to an object to be magnetized into the permanent magnet; and continuing to apply a magnetizing magnetic field to the object by the magnetizing magnetic field applying means
Implementation Method 2
while cooling the object from a temperature of its Curie point or above to a temperature of below the Curie point
Data Source
AI summary
A method of magnetizing into a permanent magnet comprises placing magnetizing magnetic field applying means to be adjacent to an object to be magnetized into the permanent magnet, and continuing to apply a magnetizing magnetic field to the object by the magnetizing magnetic field applying means while cooling the object from a temperature of its Curie point or above to a temperature of below the Curie point.