Preparation of ring-shaped composite bonded magnets with continuously controlled anisotropy distribution for internal space

Abstract

Abstract. We have already reported an advanced method for producing a radially-anisotropic rare earth composite bonded magnet with continuously controlled direction of anisotropy. The magnet has been applied to an inner rotor as a practical usage. In this study, the outstanding preparation method was adopted into the preparation of a magnet applied for an outer rotor. An optimized condition of extrusion and compaction at an elevated temperature could be obtained. In addition, a low pressure configuration to the ring-shaped magnet from plural preformed magnets was carried out, which had specific distribution of magnetic anisotropy for internal space for a small motor, by using self recoverability based on the viscous deformation without an alignment field. No deterioration of magnetic properties was detected through the process even if those magnets were miniaturized. Resultantly, the (BH) max of a ring-shaped magnet with the continuously controlled direction of magnetic anisotropy attained the value of 186 kJ/m 3 , and we obtained sine-wave magnetic anisotropy distribution, even if those magnets were miniaturized. IntroductionFurther improvements in performance of small motors are strongly required from the standpoints of environment protection and saving of resources. In order to realize a high efficiency motor, a miniaturized magnet with excellent magnetic properties is indispensable.This contribution reports an optimized preparation process for an arc-shape magnet with continuously controlled direction of anisotropy by taking advantage of the previously reported technique [1] in order to apply it to an outer rotor. The magnetic properties of the arc-shaped magnets did not degrade through the process. It was also clarified that the direction of anisotropy in the ring-shaped magnets can be controlled continuously under an application of an alignment field with one direction together with a mechanical design of preformed magnets before deformation. Finally, we succeeded in obtaining a 12 pole ring shaped magnet with (BH) max and remanence values of 186 kJ/m 3 and 1.03 T, respectively, and static magnetic field for internal space can be detected.

Comparison and Analysis of Sodium Silicate and Epoxy Bonded NdFeB Magnets

“…Especially, NdFeB magnets display a good magnetic properties prepared by a sintering method [2]. However, sintered magnets have disadvantages in thin section, complex shape or accurate size [3]. Hence, bonded NdFeB magnets owning to their more formability have attracted a great deal of attention [4].…”

Composite Bonded Magnets With Self-Recoverability for Miniaturized Anisotropic Magnet Rotor

“…Through an investigation on the conditions to achieve the self-recoverability, we obtained an optimized one at a temperature of 433 K, an alignment field of 1.4 MA/m and a compacting pressure of 50 MPa, respectively [1], [2]. The range of the properties in the obtained preformed magnets was 156-180 in and 6.1-6.2 in density.…”