Compositions – Magnetic – With wax – bitumen – resin – or gum
Reexamination Certificate
1999-03-31
2001-02-13
Sheehan, John (Department: 1742)
Compositions
Magnetic
With wax, bitumen, resin, or gum
C428S687000, C148S302000
Reexamination Certificate
active
06187217
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a magnet alloy ribbon, and particularly to a rare earth permanent magnet alloy ribbon, and a resin bonded magnet using a magnet powder obtained from the alloy ribbon.
BACKGROUND ART
In regard to a method of producing an alloy ribbon by jetting an alloy melt of a rare earth magnet material on a single metallic roll, Japanese Examined Patent Publication No. 3-52528 discloses in line 30 of column 7 on page 4 to line 42 of column 9 on page 5 that an alloy ingot sample is placed in a quartz tube and melted, and then the melt is jetted at a constant speed on a metallic disk having too high heat capacity for the melt through a circular orifice provided in the lower portion of the quartz tube to obtain an alloy ribbon. Japanese Unexamined Patent Publication No. 59-64739 reports that for a rare earth-transition metal-B system magnet composition, the rotational speed of a roll is an important factor which influences the magnetic properties of an alloy ribbon.
However, consideration has not been given to how the detailed dimensions, shape and surface state of an alloy ribbon affect magnetic properties.
In addition, a permanent magnet material produced by a conventional rapid cooling method has the following problems.
1) Magnetic properties deteriorate due to variations in the micro structure which constitutes the alloy ribbon.
2) In the formation of a bonded magnet, when a resin is nonuniformly adhered to a magnet powder, reliability, particularly corrosion resistance, deteriorates.
SUMMARY OF INVENTION
The present invention has been achieved for solving the problems of a conventional technique. In consideration of the surface state of the surface (roll surface) in contact with a roll for mainly cooling an alloy ribbon, a first object of the present invention is to provide an alloy ribbon having excellent magnet characteristics.
A second object of the present invention is to provide a resin bonded magnet having excellent magnetic characteristics and reliability, and formed by bonding a resin and a powder produced by grinding the alloy ribbon as it is or after heat treatment.
In order to achieve these objects, a magnet alloy ribbon of the present invention is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, wherein the total area ratio of dimple-like recesses after solidification, which are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 3 to 25%.
A magnet alloy ribbon of the present invention is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, wherein the total area ratio of dimple-like recesses, each of which has an area of 2000 &mgr;m
2
or more and which are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 0 to 5%.
A magnet alloy ribbon of the present invention is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, wherein the d/t ratio of the average depth (d) of dimple-like recesses to the average thickness (t) of the alloy ribbon after solidification, which recesses are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 0.1 to 0.5.
A resin bonded magnet of the present invention is formed by grinding a magnet alloy ribbon as it is or after heat treatment, which is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, to form a powder; mixing the thus-obtained power and a resin; and then molding the mixture; wherein the total area ratio of dimple-like recesses after solidification, which are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 3 to 25%.
A resin bonded magnet of the present invention is formed by grinding a magnet alloy ribbon as it is or after heat treatment, which is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, to form a powder; mixing the thus-obtained powder and a resin; and then molding the mixture; wherein the total area ratio of dimple-like recesses, each of which has an area of 2000 &mgr;m
2
or more and which are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 0 to 5%.
A resin bonded magnet of the present invention is formed by grinding a magnet alloy ribbon as it is or after heat treatment, which is obtained by jetting a R-TM-B system (R is a rare earth element such as Nd or Pr, and TM is a transition metal) alloy melt on a rotating metallic roll to rapidly solidify the alloy melt, to form a powder; mixing the thus-obtained powder and a resin; and then molding the mixture; wherein the d/t ratio of the average depth (d) of dimple-like recesses to the average thickness (t) of the alloy ribbon after solidification, which recesses are present in the surface (roll surface) of the ribbon in contact with the roll during solidification, is 0.1 to 0.5.
In accordance with claims the present invention, the surface state of the surface (roll surface) of the magnet alloy ribbon which contacts the roll, particularly the area ratio of dimple-like recesses present in the surface, is defined to provide an alloy ribbon having excellent magnet properties.
In accordance with therefor of the present invention, the thus-obtained alloy ribbon is ground as it is or after heat treatment to form a powder, and the thus-obtained powder is mixed with a resin and then molded to provide a resin bonded magnet having excellent magnetic properties and reliability.
REFERENCES:
patent: 5209789 (1993-05-01), Yoneyama et al.
patent: 5622768 (1997-04-01), Watanabe et al.
patent: 5817222 (1998-10-01), Kuneko
patent: 5993939 (1999-11-01), Fukuno et al.
patent: 59-64739 (1984-04-01), None
patent: 3-52528 (1991-08-01), None
patent: 8-260112 (1996-10-01), None
Arai Akira
Kato Hiroshi
Harness & Dickey & Pierce P.L.C.
Seiko Epson Corporation
Sheehan John
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