Rare earth-sintered magnet, method of manufacturing a rare earth-sintered body, method of manufacturing a rare earth-sintered magnet, and linear motor using a rare earth-sintered magnet

Patent metadata

Field	Value
Publication number	US-2022044852-A1
Application number	US-201816500174-A
Country	US
Kind code	A1
Filing date	Apr 5, 2018
Priority date	Apr 7, 2017
Publication date	Feb 10, 2022
Grant date	—

Abstract

Disclosed is a rare earth-sintered magnet in which a plurality of magnetic material particles are sintered. Surface magnetic flux density has a greatest value of 350 mT to 600 mT, the rare earth-sintered magnet has a thickness of 1.5 mm to 6 mm, a cross section of the rare earth-sintered magnet taken along a thickness direction is non-circular, and the cross section has an area in which axes of easy magnetization of the magnetic material particles has polar anisotropic orientation.

First claim

1 . A rare earth-sintered magnet in which a plurality of magnetic material particles are sintered,
wherein surface magnetic flux density has a greatest value of 350 mT to 600 mT, wherein the rare earth-sintered magnet has a thickness of 1.5 mm to 6 mm, wherein a cross section of the rare earth-sintered magnet taken along a thickness direction is non-circular, and wherein the cross section has an area in which axes of easy magnetization of the magnetic material particles has polar anisotropic orientation.

2 . The rare earth-sintered magnet according to claim 1 , wherein in the non-circular cross section, a ratio of the thickness to a length in a direction perpendicular to the thickness direction is in the range of 0.1 to 0.3.

3 . A method of manufacturing a rare earth-sintered body whose cross section taken along a thickness direction is non-circular and which has an area having polar anisotropic orientation, the method comprising:
a step of forming polar anisotropic orientation of at least a portion of an area in a compact by applying a pulsed magnetic field to the compact, the compact being obtained by molding a mixture having magnet powder and a polymer resin; and a step of sintering the compact having polar anisotropic orientation.

4 . A method of manufacturing a rare earth-sintered body comprising:
a step of orienting at least a portion of an area in a compact by applying a pulsed magnetic field to the compact, the compact being obtained by molding a mixture having magnet powder and a polymer resin; and a step of sintering the oriented compact, wherein Shore A hardness of the mixture is greater than or equal to A30 at room temperature, and wherein the step of orienting is performed at a temperature that causes melt viscosity of the mixture to be lower than or equal to 900 Pa·s.

5 . The method of manufacturing a rare earth-sintered body according to claim 4 , wherein the step of orienting includes a step of forming polar anisotropic orientation of at least a portion of an area in the compact.

6 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein a thickness of the compact to which a pulsed magnetic field is applied is in the range of 1.5 mm to 6 mm.

7 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein Shore A hardness of the mixture is greater than or equal to A30 at room temperature.

8 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein the step of forming polar anisotropic orientation is performed at a temperature that causes melt viscosity of the mixture to lower than or equal to 900 Pa·s.

9 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein the step of forming polar anisotropic orientation is performed at a temperature that causes melt viscosity of the mixture to be lower than or equal to 300 Pa·s.

10 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein in the step of sintering, the compact is sintered under pressure.

11 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein the polymer resin is a hydrocarbon based-resin without containing a heteroatom.

12 . The method of manufacturing a rare earth-sintered body according to claim 3 , wherein a magnetic powder content in the mixture is in the range of 50% to 60% by volume.

13 . The method of manufacturing a rare earth-sintered body according to claim 3 , further comprising a step of magnetizing a sintered body after the step of sintering the compact.

14 . A linear motor comprising:
one or more rare earth-sintered magnets according to claim 1 , the one or more rare earth-sintered magnets being arranged in a linear direction; and an armature configured to face the rare earth-sintered magnets through an air gap, wherein one of the rare earth-sintered magnets and the armature is used as a stator and another is used as a movable element, so that the stator and the movable element move relative to each other.

Assignees

• Nitto Denko Corp

Inventors

• Fujikawa Kenichi
• Yamamoto Takashi
• Saito Shoichiro
• Ozaki Takashi
• Kume Katsuya
• Hirano Yuki

Classifications

• H02K15/03

  having permanent magnets · CPC title

• H01F7/02

  Permanent magnets {[PM]} · CPC title

• H01F1/0577 Primary

  sintered · CPC title

• H02K41/031

  of the permanent magnet type · CPC title

• H01F41/02

  for manufacturing cores, coils, or magnets (H01F41/14 takes precedence; for dynamo-electric machines H02K15/00) · CPC title