CA1301602C - Method and assembly for producing extruded permanent magnet articles - Google Patents
Method and assembly for producing extruded permanent magnet articlesInfo
- Publication number
- CA1301602C CA1301602C CA000565893A CA565893A CA1301602C CA 1301602 C CA1301602 C CA 1301602C CA 000565893 A CA000565893 A CA 000565893A CA 565893 A CA565893 A CA 565893A CA 1301602 C CA1301602 C CA 1301602C
- Authority
- CA
- Canada
- Prior art keywords
- core
- charge
- permanent magnet
- container
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims description 28
- 239000002245 particle Substances 0.000 claims abstract description 17
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 16
- 239000000956 alloy Substances 0.000 claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims abstract description 4
- 238000001125 extrusion Methods 0.000 claims description 36
- 229910000975 Carbon steel Inorganic materials 0.000 claims description 9
- 239000010962 carbon steel Substances 0.000 claims description 9
- 239000010935 stainless steel Substances 0.000 claims description 6
- 229910001220 stainless steel Inorganic materials 0.000 claims description 6
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 4
- 239000000696 magnetic material Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims 2
- 239000007787 solid Substances 0.000 description 6
- 239000000843 powder Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- 238000010943 off-gassing Methods 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000011802 pulverized particle Substances 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
- H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
- H01F1/083—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together in a bonding agent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0266—Moulding; Pressing
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
- Powder Metallurgy (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for producing a compacted fully dense permanent magnet by providing a particle charge of a permanent magnet alloy composition from which the article is to be made and placing the charge in a cylindrical container having a generally axially positioned core with the charge surrounding the core within the container. The container and charge are heated to an elevated temperature and extruded to compact the charge to a substantially fully dense permanent magnet article.
A method for producing a compacted fully dense permanent magnet by providing a particle charge of a permanent magnet alloy composition from which the article is to be made and placing the charge in a cylindrical container having a generally axially positioned core with the charge surrounding the core within the container. The container and charge are heated to an elevated temperature and extruded to compact the charge to a substantially fully dense permanent magnet article.
Description
l BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to a method and assembly for producing extruded permanent magnet articles from particle charqes of permanent magnet alloys.
BRIEF DESCRIPTION OF THE D~AWINGS
Fig. 1 shows a conventional assembly of permanent magnet segments in association with a motor shaft;
Fig. 2 shows a conventional assembly of a motor shaft and an associated cylindrical permanent magnet;
Fig. 3 shows in veLtical cross-section an embodiment of an assembly in accordance with the invention for use in the method thereof to produce an extruded magnet; and Fig. 4 is a top view of the assembly of Fig. 3.
t5 Description of the Prior Art It is known to produce permanent magnet articles by powder metallurgy techniques, which include the consolidation of particles of the permanent magnet alloys. These practices are employed with permanent magnet alloys of at least one rare earth element and transistion element. These conventional practices generally include the steps of aligning, pressing and sintering.
With prior art practices of this type, high energy product ~BHmaX) and uniaxial anisotropic crystal alignment is achieved, and this combination finds utility in various permanent magnet applications.
Uniaxial anisotropic crystal alignment, however, is not always advantageous for magnet applications for rotating l machinery, motor rotors, beam focusing devices and the like. For these applications a [lOO] fiber texture wherein the C
crystallographic axis is perpendicular to the axis of the magnet may be desired. One of the primary applications for magnets of S this construction is for use in DC motors. In this application, with conventional practice, multiple segments of uniaxial anistropic magnets are needed to form the armature for the motor, which segments are identified as 2 positioned around a motor shaft 4 in Fig. l.
To obviate the need for the use of a plurality of magnet segments, as shown in Fig. 1, it is known to extrude a cylindrical magnet conforming to the required dimensions of the motor shaft. An extruded magnet 6 in association with a motor shaft 4 is shown in Fig. 2.
Cylindrical, extruded magnets, as shown in Fig. 2, are conventionally produced by the use of a cylindrical extrusion container. Magnet alloy particles are introduced to the container, and the container is outgassed, evacuated and sealed.
Thereafter, the container is heated to extrusion temperature and extruded to consolidate the particles to substantially full density. The hollow center of the magnet is achieved by the use of a solid cylinder or mandrel of a diameter corresponding to the internal diameter of the magnet to be produced, which cylinder is attached to the extrusion ram. This solid cylinder moves with the extrusion ram during the extrusion operation and thereby maintains the desired inner diameter of the extruded magnet. It is difficult to maintain concentricity of the inner and outer peripheries of the extruded magnet because the mandrel tends to :~q~
wander and thus is not maintained in axial alignment during the extrusion operation. In addition, at the high extru~ion ratios breaking of the mandrel may occur. It may be seen, there~ore, that in producing cylindrical magnets by conventional extrusion practices, a cylindrical magnet having the required concentric dimensions is difficult to achieve.
OBJECTS AND SUMMARY OF THE INVEMTION
It i5 accordingly a primary object of the present invention to provide an extrusion method and assembly for use therewith that achieves improved concentricity in the production of extruded hollow cylindrical magnets.
A more specific object of the invention is a method and assembly for use therewith that enables the production of a complete assembly, including a permanent magnet and associated 1~ shaft in a single extrusion operation.
Broadly, in accordance with the method of invention for producing a compacted fully dense permanent magnet article, a particle charge is provided of a permanent magnet alloy composition from which the permanent magnet artlcle ls to be made. The particle charge is placed in a cylindrical con~ainer having a generally axially po~itioned core with the charge surrounding the core within the container. The container is evacuated and sealed against the atmosphere. The container and particle charge are heated to elevated temperature and the container and charge are then extruded to compact the charge to substantially full density to thereby produce a substantially fully dense permanent magnet article.
,, ~
, l ~t31 ~()2 To facilitate removal of the core to produce the desired cylindrical magnet article, a separating medium, such as magnesium oxide, may be provided on the core. The core may be of carbon steel, a soft magnet material or stainless steel. ~uring the extrusion operation, the core may be bonded to the permanent magnet alloy. This is advantageous from the standpoint of producing a unitary magnet and shaft assembly during the extrusion operation.
Extrusion ratios within the range of l.S:l to 50:1 may be employed with extrusion temperatures within the range of 500 to 1200C.
The method of the invention finds particular use in producing rare earth element containing permanent magnets. More specifically, it may be used in the production of magnets of this type wherein at least one rare earth element, such as samarium, neodymium and dysprosium, may be used with a transition element, such as iron and cobalt, plus boron andtor carbon.
The invention for use in producing a compacted, fully dense permanent magnet article by extrusion includes a cylindrical container having a core generally axially positioned therein.
The mandrel defines an annular chamber within the container. A
particle charge of a permanent magnet alloy from which the article is to be made is provided within this annular chamber.
Means are provided for sealing the annular chamber.
A separating medium may be provided on the core. This facilitates removal of the core from the compacted magnet after extrusion. The core may be constructed of carbon steel, a soft magnet material or stainless steel.
.,..., .,~
1 DETAILED D~SCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with one embodiment of the invention, with reference to Figs. 3 and 4, there is shown a cylindrical container 8 having end plates 10 with axial openings 11 connected at opposite ends of the container, as by welding (not shown) to seal the container. A solid core 12 is connected at opposite ends thereof to the plates 10 and a portion extends through openings 11. The core is axially positioned within the container 8 to define therein an annular chamber 14 surrounding the core.
Particles F of the magnet alloy composition from which the magnet is to be constructed are provided within the annular chamber 14 of the container 8.
The assembly of Figs.3 and 4 so constructed is then after outgassing heated to extrusion temperature and extruded in conventional extruding apparatus to compact the particles in the container to substantially full density. Thereafter, the core 12 may be removed from the compacted hollow cylindrical magnet.
This may be faclitated by having the core provided with a separating medium, such as magnesium oxide, on the surface 2~ thereof. Alternately, the core may be bonded to the cylindrical A
~3~?lf~
1 magnet for use as an assembly in the production of a conventional motor rotor, as shown in Fig. 2.
Example 1 A carbon steel extrusion container was made with a solid low-carbon rod, 3/4~ in diameter, welded axially to the top and bottom plates of a mild carbon steel can. Atomized (NdDy)l5Fe79B6 powder was put into the 3-1/8~ diameter can and the can was heated to 150C, evacuated and sealed. The container was then heated to 927C and extruded with a ratio of 13.8:1.
The final extrusion consisted of a 0.3~ diameter steel rod surrounded by a ring shaped magnet with a wall thickness of about 0.25~. The magnetic properties are listed in Table 1. The identical properties along two orthogonal directions perpendicular to the extrusion direction indicates that a [100]
fiber texture is obtained. This is the same magnetic behavior as is observed for magnets extruded by conventional methods.
These extruded magnets, with rods at their centers, can directly be magnetized into multiple poles and used for any type of rotating assembly.
Sample Test Br Hc Hci BHmax Desiqnation Direction kG kOe kOe MGOe EX-267 Axial 3.8 3.3 15.3 3.1 Transverse 1 7.3 6.4 15.8 12.3 Transverse 2 7.2 6.3 15.7 11.6 Example 2 To compare the practice of Example 1 with a conventional , ~ , practice, the identical powder used in Example 1, (NdDy)15Fe79B6, 1 was placed into a 3-l/8~ diameter can and the can was heated to 150C, evacuated and sealed. The can was then heated to 927C
and extruded with a ratio of 13.8:1. The magnetic properties of the resultant solid cylinder are presented in Table II. The magnetic properties are very similar to those obtained in Example 1. Thus, the extrusion technique of Example l in accordance with the invention will produce magnetic properties comparable to a conventional magnet extrusion method.
TABLE II
Sample Test Br Hc Hci ~Hmax Desi~nation Direction kG kOe kOe MGOe EX-235 Axial 3.6 3.1 13.9 2.7 Transverse 1 7.1 6.1 14.0 10.9 Transverse 2 7.1 6.1 14.1 11.0 ExamPle 3 The same powder as used in Examples 1 and 2 was placed in a carbon steel extrusion container. This extrusion container was in the shape of a hollow circular cylinder, 3-1/8~ OD and 3~4~
ID. The container was evacuated, sealed and heated to 927C and extruded at a 10:1 extrusion ratio. The inner diameter was maintained during extrusion by affixing a solid mandrel to the ram of the extrusion press in accordance with conventional practice. The magnetic properties, Table III, are similar to the properties presented in Tables I and II. The concentricity defined as the ratio of minimum to maximum wall thickness, was calculated to be 0.90. This value is poorer than the concentricit~, 0.95, measured on the sample extruded in Example 1 in accordance with the invention.
13-~161)Z
1 Table III
Sample Test Br Hc Hci BHmax Desiqnation Dire tion kG kOe kOe MGOe EX-261 Axial 3.5 3.0 14.4 2.6 Transverse 7.4 6.5 16.5 12.4 As may be seen from the above descriptions and Examples, the invention provides for the production of a hollow permanent magnet by an extrusion practice wherein the desired dimensions of the magnet may be maintained while achieving permanent magnet properties comparable to conventional practices used for this purpose.
It is to be understood that the shape of the core may include symmetrical geometries other than cylindrical. The particles of magnetic material for compaction may be produced by atomization, rapidly solidified ribbon, cast and pulverized particles, direct cast ingots or particles made by a reduction-diffusion practice.
Since the core may be bonded to the compacted magnet during extrusion, an assembly may be produced having an outer shell of a permanent magnet alloy and a soft magnetic inner core, with the inner core acting to direct magnetic flux.
Field of the Invention This invention relates to a method and assembly for producing extruded permanent magnet articles from particle charqes of permanent magnet alloys.
BRIEF DESCRIPTION OF THE D~AWINGS
Fig. 1 shows a conventional assembly of permanent magnet segments in association with a motor shaft;
Fig. 2 shows a conventional assembly of a motor shaft and an associated cylindrical permanent magnet;
Fig. 3 shows in veLtical cross-section an embodiment of an assembly in accordance with the invention for use in the method thereof to produce an extruded magnet; and Fig. 4 is a top view of the assembly of Fig. 3.
t5 Description of the Prior Art It is known to produce permanent magnet articles by powder metallurgy techniques, which include the consolidation of particles of the permanent magnet alloys. These practices are employed with permanent magnet alloys of at least one rare earth element and transistion element. These conventional practices generally include the steps of aligning, pressing and sintering.
With prior art practices of this type, high energy product ~BHmaX) and uniaxial anisotropic crystal alignment is achieved, and this combination finds utility in various permanent magnet applications.
Uniaxial anisotropic crystal alignment, however, is not always advantageous for magnet applications for rotating l machinery, motor rotors, beam focusing devices and the like. For these applications a [lOO] fiber texture wherein the C
crystallographic axis is perpendicular to the axis of the magnet may be desired. One of the primary applications for magnets of S this construction is for use in DC motors. In this application, with conventional practice, multiple segments of uniaxial anistropic magnets are needed to form the armature for the motor, which segments are identified as 2 positioned around a motor shaft 4 in Fig. l.
To obviate the need for the use of a plurality of magnet segments, as shown in Fig. 1, it is known to extrude a cylindrical magnet conforming to the required dimensions of the motor shaft. An extruded magnet 6 in association with a motor shaft 4 is shown in Fig. 2.
Cylindrical, extruded magnets, as shown in Fig. 2, are conventionally produced by the use of a cylindrical extrusion container. Magnet alloy particles are introduced to the container, and the container is outgassed, evacuated and sealed.
Thereafter, the container is heated to extrusion temperature and extruded to consolidate the particles to substantially full density. The hollow center of the magnet is achieved by the use of a solid cylinder or mandrel of a diameter corresponding to the internal diameter of the magnet to be produced, which cylinder is attached to the extrusion ram. This solid cylinder moves with the extrusion ram during the extrusion operation and thereby maintains the desired inner diameter of the extruded magnet. It is difficult to maintain concentricity of the inner and outer peripheries of the extruded magnet because the mandrel tends to :~q~
wander and thus is not maintained in axial alignment during the extrusion operation. In addition, at the high extru~ion ratios breaking of the mandrel may occur. It may be seen, there~ore, that in producing cylindrical magnets by conventional extrusion practices, a cylindrical magnet having the required concentric dimensions is difficult to achieve.
OBJECTS AND SUMMARY OF THE INVEMTION
It i5 accordingly a primary object of the present invention to provide an extrusion method and assembly for use therewith that achieves improved concentricity in the production of extruded hollow cylindrical magnets.
A more specific object of the invention is a method and assembly for use therewith that enables the production of a complete assembly, including a permanent magnet and associated 1~ shaft in a single extrusion operation.
Broadly, in accordance with the method of invention for producing a compacted fully dense permanent magnet article, a particle charge is provided of a permanent magnet alloy composition from which the permanent magnet artlcle ls to be made. The particle charge is placed in a cylindrical con~ainer having a generally axially po~itioned core with the charge surrounding the core within the container. The container is evacuated and sealed against the atmosphere. The container and particle charge are heated to elevated temperature and the container and charge are then extruded to compact the charge to substantially full density to thereby produce a substantially fully dense permanent magnet article.
,, ~
, l ~t31 ~()2 To facilitate removal of the core to produce the desired cylindrical magnet article, a separating medium, such as magnesium oxide, may be provided on the core. The core may be of carbon steel, a soft magnet material or stainless steel. ~uring the extrusion operation, the core may be bonded to the permanent magnet alloy. This is advantageous from the standpoint of producing a unitary magnet and shaft assembly during the extrusion operation.
Extrusion ratios within the range of l.S:l to 50:1 may be employed with extrusion temperatures within the range of 500 to 1200C.
The method of the invention finds particular use in producing rare earth element containing permanent magnets. More specifically, it may be used in the production of magnets of this type wherein at least one rare earth element, such as samarium, neodymium and dysprosium, may be used with a transition element, such as iron and cobalt, plus boron andtor carbon.
The invention for use in producing a compacted, fully dense permanent magnet article by extrusion includes a cylindrical container having a core generally axially positioned therein.
The mandrel defines an annular chamber within the container. A
particle charge of a permanent magnet alloy from which the article is to be made is provided within this annular chamber.
Means are provided for sealing the annular chamber.
A separating medium may be provided on the core. This facilitates removal of the core from the compacted magnet after extrusion. The core may be constructed of carbon steel, a soft magnet material or stainless steel.
.,..., .,~
1 DETAILED D~SCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with one embodiment of the invention, with reference to Figs. 3 and 4, there is shown a cylindrical container 8 having end plates 10 with axial openings 11 connected at opposite ends of the container, as by welding (not shown) to seal the container. A solid core 12 is connected at opposite ends thereof to the plates 10 and a portion extends through openings 11. The core is axially positioned within the container 8 to define therein an annular chamber 14 surrounding the core.
Particles F of the magnet alloy composition from which the magnet is to be constructed are provided within the annular chamber 14 of the container 8.
The assembly of Figs.3 and 4 so constructed is then after outgassing heated to extrusion temperature and extruded in conventional extruding apparatus to compact the particles in the container to substantially full density. Thereafter, the core 12 may be removed from the compacted hollow cylindrical magnet.
This may be faclitated by having the core provided with a separating medium, such as magnesium oxide, on the surface 2~ thereof. Alternately, the core may be bonded to the cylindrical A
~3~?lf~
1 magnet for use as an assembly in the production of a conventional motor rotor, as shown in Fig. 2.
Example 1 A carbon steel extrusion container was made with a solid low-carbon rod, 3/4~ in diameter, welded axially to the top and bottom plates of a mild carbon steel can. Atomized (NdDy)l5Fe79B6 powder was put into the 3-1/8~ diameter can and the can was heated to 150C, evacuated and sealed. The container was then heated to 927C and extruded with a ratio of 13.8:1.
The final extrusion consisted of a 0.3~ diameter steel rod surrounded by a ring shaped magnet with a wall thickness of about 0.25~. The magnetic properties are listed in Table 1. The identical properties along two orthogonal directions perpendicular to the extrusion direction indicates that a [100]
fiber texture is obtained. This is the same magnetic behavior as is observed for magnets extruded by conventional methods.
These extruded magnets, with rods at their centers, can directly be magnetized into multiple poles and used for any type of rotating assembly.
Sample Test Br Hc Hci BHmax Desiqnation Direction kG kOe kOe MGOe EX-267 Axial 3.8 3.3 15.3 3.1 Transverse 1 7.3 6.4 15.8 12.3 Transverse 2 7.2 6.3 15.7 11.6 Example 2 To compare the practice of Example 1 with a conventional , ~ , practice, the identical powder used in Example 1, (NdDy)15Fe79B6, 1 was placed into a 3-l/8~ diameter can and the can was heated to 150C, evacuated and sealed. The can was then heated to 927C
and extruded with a ratio of 13.8:1. The magnetic properties of the resultant solid cylinder are presented in Table II. The magnetic properties are very similar to those obtained in Example 1. Thus, the extrusion technique of Example l in accordance with the invention will produce magnetic properties comparable to a conventional magnet extrusion method.
TABLE II
Sample Test Br Hc Hci ~Hmax Desi~nation Direction kG kOe kOe MGOe EX-235 Axial 3.6 3.1 13.9 2.7 Transverse 1 7.1 6.1 14.0 10.9 Transverse 2 7.1 6.1 14.1 11.0 ExamPle 3 The same powder as used in Examples 1 and 2 was placed in a carbon steel extrusion container. This extrusion container was in the shape of a hollow circular cylinder, 3-1/8~ OD and 3~4~
ID. The container was evacuated, sealed and heated to 927C and extruded at a 10:1 extrusion ratio. The inner diameter was maintained during extrusion by affixing a solid mandrel to the ram of the extrusion press in accordance with conventional practice. The magnetic properties, Table III, are similar to the properties presented in Tables I and II. The concentricity defined as the ratio of minimum to maximum wall thickness, was calculated to be 0.90. This value is poorer than the concentricit~, 0.95, measured on the sample extruded in Example 1 in accordance with the invention.
13-~161)Z
1 Table III
Sample Test Br Hc Hci BHmax Desiqnation Dire tion kG kOe kOe MGOe EX-261 Axial 3.5 3.0 14.4 2.6 Transverse 7.4 6.5 16.5 12.4 As may be seen from the above descriptions and Examples, the invention provides for the production of a hollow permanent magnet by an extrusion practice wherein the desired dimensions of the magnet may be maintained while achieving permanent magnet properties comparable to conventional practices used for this purpose.
It is to be understood that the shape of the core may include symmetrical geometries other than cylindrical. The particles of magnetic material for compaction may be produced by atomization, rapidly solidified ribbon, cast and pulverized particles, direct cast ingots or particles made by a reduction-diffusion practice.
Since the core may be bonded to the compacted magnet during extrusion, an assembly may be produced having an outer shell of a permanent magnet alloy and a soft magnetic inner core, with the inner core acting to direct magnetic flux.
Claims (30)
1. A method for producing a compacted fully dense permanent magnet, said method comprising:
providing a particle charge of a permanent magnet alloy composition from which said article is to be made;
placing said charge in a cylindrical container having a generally axially positioned core with said charge surrounding said core within said container; and heating said container and charge to an elevated temperature and extruding said container and charge to compact said charge to substantially fully dense permanent magnet article.
providing a particle charge of a permanent magnet alloy composition from which said article is to be made;
placing said charge in a cylindrical container having a generally axially positioned core with said charge surrounding said core within said container; and heating said container and charge to an elevated temperature and extruding said container and charge to compact said charge to substantially fully dense permanent magnet article.
2. The method of claim 1 wherein said core is removed after compacting.
3. The method of claim 1 wherein a separating medium is provided on said core.
4. The method of claim 1 wherein said core is carbon steel.
5. The method of claim 1 wherein said core is a soft magnetic material.
6. The method of claim 1 wherein said core is stainless steel.
7. The method of claim 1 wherein said core is bonded to said permanent magnet alloy during said extrusion.
8. The method of claim 1 wherein said extruding is performed with an extrusion ratio within the range of 1.5:1 to 50:1.
9. The method of claim 1 wherein said extruding is performed with said charge at a temperature within the range of 500 to 1200 C.
10. The method of claim 1 wherein said extruding is performed with an extrusion ratio within the range of 1.5:1 to 50:1 and with said charge at a temperature within the range of 500 to 1200 C.
11. A method for producing a compacted fully dense permanent magnet article, said method comprising:
providing a particle charge of a permanent magnet alloy comprising at least one rare earth element, from which said article is to be made;
placing said charge in a cylindrical container having a generally axially positioned core with said charge surrounding said core within said container; and heating said container and charge to an elevated temperature and extruding said container and charge to compact said charge to substantially full density to produce a substantially fully dense permanent magnet article.
providing a particle charge of a permanent magnet alloy comprising at least one rare earth element, from which said article is to be made;
placing said charge in a cylindrical container having a generally axially positioned core with said charge surrounding said core within said container; and heating said container and charge to an elevated temperature and extruding said container and charge to compact said charge to substantially full density to produce a substantially fully dense permanent magnet article.
12. The method of claim 11, wherein said core is removed after compacting.
13. The method of claim 11, wherein a separating medium is provided on said core.
14. The method of claim 11 wherein said core is carbon steel.
15. The method of claim 11 wherein said core is a soft magnetic material.
16. The method of claim 11 wherein said core is a stainless steel.
17. The method of claim 11 wherein said core is bonded to said permanent magnet alloy during said extrusion.
18. The method of claim 11 wherein said extruding is performed with an extrusion ratio within the range of 1.5:1 to 50:1.
19. The method of claim 11 wherein said extruding is performed with said charge at a temperature within the range of 500 to 1200 C.
20. The method of claim 11 wherein said extruding is performed with an extrusion ratio within the range of 1.5:1 to 50:1 and with said charge at a temperature within the range of 500 to 1200 C.
21. An assembly adapted for use in producing a compacted, fully dense permanent magnet article by extrusion, said assembly comprising a cylindrical container having a core generally axially positioned within said container and defining an annular chamber within said container, and a particle charge of a permanent magnet alloy from which said article is to be made provided within said annular chamber.
22. The assembly of claim 21 wherein a separating medium is provided on said core.
23. The assembly of claim 21 wherein said core is carbon steel.
24. The assembly of claim 21 wherein said core is a soft magnet material.
25. The assembly of claim 21 wherein said core is stainless steel.
26. An assembly adapted for use in producing a compacted, fully dense permanent magnet article by extrusion, said assembly comprising a cylindrical container having a core generally axially positioned within said container and defining an annular chamber within said container, and a particle charge of a permanent magnet alloy comprising at least one rare earth element from which said article is to be made provided within said annular chamber.
27. The assembly of claim 26 wherein a separating medium is provided on said core.
28. The assembly of claim 26 wherein said core is carbon steel.
29. The assembly of claim 26 wherein said core is a soft magnet material.
30. The assembly of claim 26 wherein said core is stainless steel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12235187A | 1987-11-18 | 1987-11-18 | |
| US122,351 | 1987-11-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1301602C true CA1301602C (en) | 1992-05-26 |
Family
ID=22402192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000565893A Expired - Fee Related CA1301602C (en) | 1987-11-18 | 1988-05-04 | Method and assembly for producing extruded permanent magnet articles |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0318131B1 (en) |
| JP (1) | JPH01151216A (en) |
| AT (1) | ATE87764T1 (en) |
| CA (1) | CA1301602C (en) |
| DE (1) | DE3879886T2 (en) |
| ES (1) | ES2040341T3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10312102B4 (en) * | 2003-03-19 | 2015-10-08 | Robert Bosch Gmbh | Device for measuring a level of a liquid in a container |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3447230A (en) * | 1967-01-05 | 1969-06-03 | Sylvania Electric Prod | Art of making seamless hollow bodies from sinterable powders |
| US3918867A (en) * | 1969-06-28 | 1975-11-11 | Philips Corp | Device for extruding permanent magnet bodies |
| JPS5120592A (en) * | 1974-08-13 | 1976-02-18 | Matsushita Electric Industrial Co Ltd | Kyojiseitaifunmatsuno jikaichuseikeiyokanagata |
| JPS5176108A (en) * | 1974-12-27 | 1976-07-01 | Hitachi Metals Ltd | FUNMATSUYAKINHONYORUKANSEIZOHO OYOBIFUNMATSUJUTENYOKI |
| GB1534221A (en) * | 1977-07-25 | 1978-11-29 | Ipari Szerelveny & Gepgyar | Process for the production of sleeves and like workpieces from hard metals of high cobalt content |
| US4579607A (en) * | 1982-04-19 | 1986-04-01 | Matsushita Electric Industrial Company, Limited | Permanent Mn-Al-C alloy magnets and method for making same |
| JPS60214515A (en) * | 1984-04-10 | 1985-10-26 | Seiko Epson Corp | Manufacture of cylindrical permanent magnet |
| JPH0626169B2 (en) * | 1984-12-27 | 1994-04-06 | ティーディーケイ株式会社 | Method and apparatus for forming rare earth magnet in magnetic field |
| US4602952A (en) * | 1985-04-23 | 1986-07-29 | Cameron Iron Works, Inc. | Process for making a composite powder metallurgical billet |
| US4640815A (en) * | 1985-10-17 | 1987-02-03 | Crucible Materials Corporation | Method and assembly for producing extrusion-clad tubular product |
| CA1269029A (en) * | 1986-01-29 | 1990-05-15 | Peter Vernia | Permanent magnet manufacture from very low coercivity crystalline rare earth-transition metal-boron alloy |
| JPH0624176B2 (en) * | 1986-03-29 | 1994-03-30 | 信越化学工業株式会社 | Method for producing polar anisotropic long molded products |
-
1988
- 1988-05-04 CA CA000565893A patent/CA1301602C/en not_active Expired - Fee Related
- 1988-05-31 AT AT88304916T patent/ATE87764T1/en not_active IP Right Cessation
- 1988-05-31 DE DE8888304916T patent/DE3879886T2/en not_active Expired - Fee Related
- 1988-05-31 ES ES198888304916T patent/ES2040341T3/en not_active Expired - Lifetime
- 1988-05-31 EP EP88304916A patent/EP0318131B1/en not_active Expired - Lifetime
- 1988-10-04 JP JP63249177A patent/JPH01151216A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3879886D1 (en) | 1993-05-06 |
| DE3879886T2 (en) | 1993-08-26 |
| ES2040341T3 (en) | 1993-10-16 |
| EP0318131A1 (en) | 1989-05-31 |
| ATE87764T1 (en) | 1993-04-15 |
| EP0318131B1 (en) | 1993-03-31 |
| JPH01151216A (en) | 1989-06-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4942322A (en) | Permanent magnet rotor with bonded sheath | |
| US4151435A (en) | Stator structure using forming curved wafer thin magnets from rare earth-cobalt alloy powders | |
| US3977918A (en) | Method of making magnets | |
| US5039292A (en) | Device for manufacturing magnetically anisotropic magnets | |
| US6423264B1 (en) | Process for forming rotating electromagnets having soft and hard magnetic components | |
| US6509667B1 (en) | Rotor for a reluctance motor | |
| US4325757A (en) | Method of forming thin curved rare earth-transition metal magnets from lightly compacted powder preforms | |
| US4990306A (en) | Method of producing polar anisotropic rare earth magnet | |
| US7740714B2 (en) | Method for preparing radially anisotropic magnet | |
| US4881984A (en) | Consolidation of magnet alloy powders by extrusion and product therefrom | |
| EP1717828A1 (en) | Methods of producing radial anisotropic cylinder sintered magnet and permanent magnet motor-use cylinder multi-pole magnet | |
| US5047205A (en) | Method and assembly for producing extruded permanent magnet articles | |
| CA1301602C (en) | Method and assembly for producing extruded permanent magnet articles | |
| US4144060A (en) | Method of fabricating rare earth-transition metal magnets | |
| US4915891A (en) | Method for producing a noncircular permanent magnet | |
| EP0265016A2 (en) | Process of making a permanent magnet | |
| US5342574A (en) | Method for producing anisotropic rare earth magnet | |
| US5288454A (en) | Method of controlling the remanent induction of a sintered magnet, and the product thus obtained | |
| JPH03265102A (en) | Diametrical anisotropic cylindrical permanent magnet and manufacture thereof | |
| EP0565363B1 (en) | Method for producing anisotropic rare earth magnet | |
| RU2051456C1 (en) | Method for manufacturing magnetic circuits of electrical machines and devices | |
| JPH04112504A (en) | Manufacture of pare-earth magnet | |
| JP2000012359A (en) | Magnet and manufacturing method thereof | |
| JPH01169910A (en) | Manufacture of anisotropical nd-fe-b base magnet | |
| JP2583113B2 (en) | Rare earth magnet manufacturing method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |