EP0174735A2
Expired / Lapsed
EP
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Method of producing a permanent magnet having high and low coercivity regions
Assignee: Motors Liquidation Co
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Filing: 1985-08-09
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Granted: —
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Expires: 2005-08-09
Abstract
Abstract In accordance with a preferred embodiment of the invention, an arcuate magnet (36) is formed by selectively hot-working a composition including iron,neodymium and or praseodymium, and boron so that an edge (40) of the arcuate magnet has greater apparent coercivity than a central region (38) and the central region (38) has a higher remanence than the edge (40).
Inventors
- 👤 Robert Weir Lee
- 👤 Neal Andrew Schaffel
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 14:37
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/047; H01F1/053; H01F1/055; H01F1/057; H01F1/0571; H01F1/0575; H01F1/0576
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
65 words
A permanent magnet body having first and second regions thereof with differing magnetic properties characterised in that the body (36;42;68) comprises one or more compositions comprising iron, neodymium and/or praseodymium, and boron, and said body (36;42;68) has been hot-worked so that said first and second regions (38;40;44;46;58;60), are spaced along a surface dimension of the body (36;42;68) and differ from one another in magnetic alignment.
Claim 2
Dependent Claim
65 words
A permanent magnet body having first and second regions thereof with differing magnetic properties characterised in that the body (36;42;68) comprises one or more compositions comprising iron, neodymium and/or praseodymium, and boron, and said body (36;42;68) has been hot-worked so that said first and second regions (38;40;44;46;58;60), are spaced along a surface dimension of the body (36;42;68) and differ from one another in magnetic alignment.
Claim 3
Dependent Claim
71 words
A permanent magnet body according to claim 1, in which said body is an arcuate body (36;42), characterised in that the body (36;42) has been hot-worked so that it comprises said first region at one end (40;46) of the arcuate body (36;42) and said second region (38;44) centrally placed along the arcuate body (36;42) the first region having greater coercivity measured radially of the arcuate body (36;42) than the second region.
Claim 4
Dependent Claim
102 words
A permanent magnet body according to claim 1, shaped as an arcuate pole magnet for an electric motor, characterised in that the body (36;42) has been non-uniformly hot-worked so that it comprises said first region at one end (40;46) of the arcuate pole magnet and said second region (38;44) centrally placed along the arcuate pole magnet, the first region (40;46) having a greater magnetic coercivity measured in the direction of the radius of the arcuate pole magnet than the second region (38;44), and the second region (38;44) having a greater magnetic remanence, measured in said radial direction, than the first region (40;46).
Claim 5
Dependent Claim
88 words
A method of producing a permanent magnet body (36;42;68) according to claim 1, characterised in that the method comprises hot-pressing particles of a composition comprising iron, neodymium and/or praseodymium, and boron and having an intrinsic room temperature coercivity greater than about 1000 oersted to form a substantially fully densified body (30;48;56) of the composition, and then hot-working the body (30;48;56) non-uniformly to produce at least said two regions (38;40;44;46;58,60) in the body (36;42;68) spaced along a surface dimension of it that differ in magnetic alignment from one another.
Claim 6
Dependent Claim
80 words
A method of producing a permanent magnet body (36;68) according to claim 4, characterised in that the substantially fully densified body (30;56) has a section having at least two portions 32,34;58,60) of different thickness, and the body (30;56) is hot-worked to reduce the thickness of the thicker (32;58) of the portions and to produce at least said two regions (38,40;58,60) in the hot-worked body (36;68) spaced along a surface dimension of it that differ in magnetic alignment from one another.
Claim 7
Dependent Claim
80 words
A method of producing a permanent magnet body according to claim 4, characterised in that the substantially fully densified body is introduced into a die along with particles of a composition comprising iron, neodymium and/or praseodymium, and boron and having an intrinsic room temperature coercivity greater than about 1000 oersted, and the particles are hot-pressed and the body is hot-worked so as to form a unitary body having said first and second regions differing in magnetic alignment from one another.
References Cited (Backward Citations)
No citation records indexed.
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