Presentation Information
[P1-34]Development of Nd-Fe-B multi-pole magnetized ring magnets with high magnetic properties
*Haruhiro Komura1, Akihiro Yamane1, Kentaro Hanashima1, Toshinori Suzuki1, Yu Okawara1 (1. MINEBEA MITSUMI Inc. (Japan))
Keywords:
Nd-Fe-B,isotropic bulk magnet,pulse magnetization
There are several types of magnets that use MQ powder(*1), and Nd-Fe-B isotropic bonded magnets (hereinafter, MQ1) are widely distributed as ring magnets for motors, and are mainly used with multi-pole magnetization from the side (outer or inner circumference).In order to improve the value of motors, it is desired to improve the characteristics of magnets, and upgrading based on MQ1, which makes it easy to achieve sinusoidal magnetization, is particularly useful because it has the effect of reducing cogging, and there is a strong demand for it.Therefore, we investigated isotropic bulk magnets (hereinafter, MQ2) with the aim of achieving high magnetic properties in ring magnets.
So far, it has been reported that MQ2 tends to be slightly anisotropic in the pressing direction (hereinafter, A-direction) and is not completely isotropic.(*2) Therefore, in the case of ring magnets, it seems difficult to increase the magnetic properties because the multi-pole magnetization is from the side (hereinafter, B-direction) where the static magnetic properties decrease.However, as a result of various studies, we confirmed an interesting phenomenon in which when the density is increased and the anisotropy level in the A-direction is increased, the static magnetic properties in the B-direction, which is the magnetization direction, decrease, but the multi-pole magnetization characteristics increase. (Fig.1) Furthermore, when checking the static magnetic field analysis results, it became clear that, unlike MQ1, there was a large discrepancy between the calculated values and the measured values for MQ2, with the measured values being considerably larger.From the above, we believe that the experimental results showing an increase in multi-pole magnetization characteristics are a unique phenomenon that occurs when pulse magnetization is performed on MQ2, which has random orientation components.
To summarize the results, it became clear that by increasing the density of MQ2 and raising the level of anisotropy in the A-direction, it is possible to improve the multi-pole magnetization characteristics in the B-direction of the ring magnet.
By utilizing this phenomenon, it is possible to achieve high magnetization characteristics of ring magnets, which is expected to contribute to higher characteristics of motors and making them lighter, thinner, and smaller.
---
(*1) Electric furnace steel Vol.62 No.4 241-251,(1991)
(*2) R. W. Lee (1985). Hot-pressed neodymium-iron-boron magnets Appl. Phys. Lett. 46, 790-791 (1985).
So far, it has been reported that MQ2 tends to be slightly anisotropic in the pressing direction (hereinafter, A-direction) and is not completely isotropic.(*2) Therefore, in the case of ring magnets, it seems difficult to increase the magnetic properties because the multi-pole magnetization is from the side (hereinafter, B-direction) where the static magnetic properties decrease.However, as a result of various studies, we confirmed an interesting phenomenon in which when the density is increased and the anisotropy level in the A-direction is increased, the static magnetic properties in the B-direction, which is the magnetization direction, decrease, but the multi-pole magnetization characteristics increase. (Fig.1) Furthermore, when checking the static magnetic field analysis results, it became clear that, unlike MQ1, there was a large discrepancy between the calculated values and the measured values for MQ2, with the measured values being considerably larger.From the above, we believe that the experimental results showing an increase in multi-pole magnetization characteristics are a unique phenomenon that occurs when pulse magnetization is performed on MQ2, which has random orientation components.
To summarize the results, it became clear that by increasing the density of MQ2 and raising the level of anisotropy in the A-direction, it is possible to improve the multi-pole magnetization characteristics in the B-direction of the ring magnet.
By utilizing this phenomenon, it is possible to achieve high magnetization characteristics of ring magnets, which is expected to contribute to higher characteristics of motors and making them lighter, thinner, and smaller.
---
(*1) Electric furnace steel Vol.62 No.4 241-251,(1991)
(*2) R. W. Lee (1985). Hot-pressed neodymium-iron-boron magnets Appl. Phys. Lett. 46, 790-791 (1985).
