Compression-bonded magnet with case and method for producing the same

Patent metadata

Field	Value
Publication number	US-9818521-B2
Application number	US-201415104224-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Dec 13, 2013
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

There is provided a compression-bonded magnet with a case, which can realize high magnetic properties, high corrosion resistance and high durability strength even at low cost. The compression-bonded magnet with a case is a compression-bonded magnet with a case 1 , comprising: a compression-bonded magnet 2 comprising a rare earth magnet powder such as an isotropic Nd—Fe—B magnet powder and a resin binder of a thermosetting resin; a case 3 for inserting the compression-bonded magnet 2 ; and a sealing member 4 , wherein the compression-bonded magnet 2 is formed by compression-molding a mixture comprising the rare earth magnet powder and the resin binder into a green compact and curing the resin binder contained in the green compact, the rare earth magnet powder is contained in a large amount with respect to the entire compression-bonded magnet (for example, in a volume ratio of 85% to 90%), the sealing member 4 is fixed at an insertion opening part 3 a of the case 3 , and the compression-bonded magnet 2 is hermetically sealed by the sealing member 4 and the case 3.

First claim

The invention claimed is:

1. A compression-bonded magnet with a case, comprising a compression-bonded magnet including a rare earth magnet powder and a resin binder of a thermosetting resin, a case for inserting the compression-bonded magnet, and a sealing member, wherein the compression-bonded magnet is formed by compression-molding a mixture comprising the rare earth magnet powder and the resin binder into a green compact and curing the resin binder contained in the green compact, the sealing member is fixed at an insertion opening part for the compression-bonded magnet provided in the case, and the compression-bonded magnet is hermetically sealed by the sealing member and the case,
the sealing member is made of a cured product of a thermosetting resin, and
the resin binder and the sealing member are cured in the same step in a state where the green compact is inserted into the case.

2. The compression-bonded magnet with a case according to claim 1 , wherein the rare earth magnet powder is contained in a volume ratio of 85% to 90% with respect to the entire compression-bonded magnet.

3. The compression-bonded magnet with a case according to claim 1 , wherein the rare earth magnet powder is an isotropic Nd—Fe—B magnet powder.

4. The compression-bonded magnet with a case according to claim 1 , wherein the case is made of a non-magnetic material, the compression-bonded magnet is in an approximately columnar shape, and is magnetized in the radial direction of the column, the case is arranged so as to cover the outer peripheral surface and bottom surface sides of the column, and the sealing member is arranged on the upper surface side of the column.

5. The compression-bonded magnet with a case according to claim 4 , wherein the sealing member is interposed between a part of the column upper surface side of the outer peripheral surface of the compression-bonded magnet and the case.

6. The compression-bonded magnet with a case according to claim 1 , which is a magnet constituting a rotation angle detection sensor for use in a corrosive environment.

7. A method for producing a compression-bonded magnet with a case comprising a compression-bonded magnet including a rare earth magnet powder and a resin binder of a thermosetting resin, a case for inserting the compression-bonded magnet, and a sealing member, wherein the compression-bonded magnet is hermetically sealed by the sealing member and the case, the method comprising: a green compact molding step of compression-molding a mixture comprising the rare earth magnet powder and the resin binder to form a green compact; a green compact insertion step of inserting the green compact after curing of the resin binder or the green compact before curing of the resin binder into the case; and a sealing step of fixing the sealing member at an insertion opening part for the green compact provided in the case, wherein
the green compact insertion step involves inserting the green compact before curing of the resin binder into the case, and
the sealing step involves:
applying a thermosetting resin which serves as the sealing member after curing so as to cover a non-contact part of the green compact with the case while partially contacting the thermosetting resin with the case, in the insertion opening part for the green compact provided in the case; and
curing the thermosetting resin through heat treatment at a temperature of not lower than the thermosetting initiating temperatures of the thermosetting resin and the resin binder, thereby forming the sealing member while fixing the sealing member onto the case, and, at the same time, curing the resin binder contained in the green compact, thereby forming the compression molded-magnet.

8. The method for producing a compression-bonded magnet with a case according to claim 7 , wherein the case is made of a non-magnetic material, the green compact and the compression-bonded magnet are in an approximately columnar shape, and are magnetized in the radial direction of the column, the case is arranged so as to cover the outer peripheral surface and bottom surface sides of the column, and the sealing member is arranged on the upper surface side of the column.

9. The method for producing a compression-bonded magnet with a case according to claim 7 , wherein the case is made of a non-magnetic material, the green compact and the compression-bonded magnet are in an approximately columnar shape, and are magnetized in the radial direction of the column, the case is arranged so as to cover the outer peripheral surface and bottom surface sides of the column, the sealing member is arranged on the upper surface side of the column, the green compact has a step part which is in non-contact with the case, at least in the end part on the column upper surface side of its outer peripheral surface, and the thermosetting resin is charged into the step part in the sealing step, so that a part of the sealing member is formed in the step part.

10. The method for producing a compression-bonded magnet with a case according to claim 7 , wherein the heat treatment in the sealing step is performed at a temperature of not higher than 200° C. and normal pressure.

11. The method for producing a compression-bonded magnet with a case according to claim 7 , wherein the rare earth magnet powder is an isotropic Nd—Fe—B magnet powder, and the magnet powder is contained in a volume ratio of 85% to 90% with respect to the entire compression-bonded magnet.

Assignees

• Ntn Toyo Bearing Co Ltd

Inventors

• Miyazaki Shinji
• Harano Takuji
• Nakajima Tatsuo

Classifications

• C22C33/02

  by powder metallurgy · CPC title

• G01D5/145

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title

• B23K35/3613

  Polymers, e.g. resins · CPC title

• G01D5/14

  influencing the magnitude of a current or voltage · CPC title

• C22C2202/02

  Magnetic · CPC title