CA1172006A - Method for making cores for alternating current applications - Google Patents
Method for making cores for alternating current applicationsInfo
- Publication number
- CA1172006A CA1172006A CA000390740A CA390740A CA1172006A CA 1172006 A CA1172006 A CA 1172006A CA 000390740 A CA000390740 A CA 000390740A CA 390740 A CA390740 A CA 390740A CA 1172006 A CA1172006 A CA 1172006A
- Authority
- CA
- Canada
- Prior art keywords
- core
- powder
- cores
- insulating medium
- magnetic insulating
- 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
Links
Classifications
-
- 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
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
-
- 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
- H01F41/0206—Manufacturing of magnetic cores by mechanical means
- H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Soft Magnetic Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for producing cores from ferromagnetic powder for alternating current applications by placing a plurality of layers of ferromagnetic powder into a container, separating each layer from the other with a magnetic insulating medium and then consolidating the powder to form a core of intermediate density which is then sintered to final density.
A method for producing cores from ferromagnetic powder for alternating current applications by placing a plurality of layers of ferromagnetic powder into a container, separating each layer from the other with a magnetic insulating medium and then consolidating the powder to form a core of intermediate density which is then sintered to final density.
Description
7;Z0~6 For use in applications such as transformers it is known that cores can be made from ferromagnetic material, where the cores are constructed typically of a plurality of laminations made -from strip material. Generally, the laminations are magnetically insulated one from the other; this is achieved typically by coating the laminations with varnish and the like. This prevents in the assembled core current from circulating between the laminations to result in excessive core loss. It is also known to provide cores ! made from ferromagnetic ma~erial in powder form. With this practice, the powder may be pressed and sintered to produce laminations of the desired thickness which are then assembled to form the core. Cores constructed from laminations of ferro- ;
magnetic powder provide manufacturing cost advantages over the practice of constructing the core from laminations made from strip material. They provide, however, manufacturing disadvantages in that the sintering of ind;vidual laminations results in poor utilization of the sintering furnace. If the individual laminations are assembled prior to sintering this results in a cumbersome and expensive additional manufacturing operation in the overall practice.
. .: .
.. . .
. . .
., i~ ' ,.~ -1 ~
. . .
,:
.,. ~
., ., ili7Zt;)(~6 ., It is accordingly an object of the-invention to provide a method for manufacturing cores from ferromagnetic powder that provides, in combination, a metal core having the improved properties resulting from the use of ferromagnetic laminations , 5 achieved by an economic and efficient manufacturing practice.
This and other objects of the invention will be apparent from the following description and specific examples of the ~ practice of the invention.
'~ ~
The practice of the invention ~ s for the manufac-: 10 ture of a core for alternating current appl 00 ~ by placing a plurality of layers of the selected ferromagne~ ~wder into a container with each layer being separated one from the other.
` - When the desired number of layers, each one constituting a lamination in the final core, have been provided in the container tne powder is consolidated to form a core of intermediate density.
This core is then sintered in the conventional manner to achieve further densification. The ferromagnetic powder used in the practice of the invention may be an elemental ferromagnetic powder,a prealloyed ferromagnetic powder or a blend of ferro-, magnetic powder with one or more alloying elements. The powder may be made by conventional atomizing techniques, with examples thereof being atomized low carbon steel, atomized low carbon silicon-iron, atomized low carbon nickel-iron, or a blend of atomizing low carbon steel with nickel-molybdenum or cobalt powders singly or in combination. As is conventional practice a :
separating medium is provided between the layers or laminations in the practice of the invention. The separating medium may be in powder form or solid form, such as conventional alumina fiber sheet. If a separating medium in powder form is used such may be :' :.`
` -2-.
,~
'`
:
~::
1~7Z~)Q6 aluminum oxide, zirconium oxide or mixtures thereof. In an alternate procedure with respect to the invention each layer of ferromagnetic powder may be separately compacted within the container prior to consolidation to form the core.
More specifically with respect to the practice of the invention, in the manufacture of a core for magnetic applications the desired number of core laminations is determined. The total weight of the metal in powder form for the specific core would be divided into essentially equal portions in accordance with the ` 10 number of laminations required. Each of the portions would be introduced sequentially into a mold or die cavity having an internal cross section conforming substantially to that desired in - the core to be produced. The die would typically be provided with movable upper and lower die punches. Between each layer of ferro-magnetic material there would be provided an insulating medium : which may be solid or powder form as described hereinabove. When. ` all of the ferromagne~ic layers and insulating medium have been introduced to the die cavity, the upper and lower punches would be activated to press the powder material into a laminated core of~
,intermediate density. The density should be sufficient to permit handling particularly for conventional sintering. Sintering would be conducted in a furnace wherein the core would be moved through the furnace and heated to a temperature of, for example 2300F. This would then achieve a core with the final desired density. By using the alternate procedure of separately compacting each layer of ferromagnetic powder prior to introducing a succeed-!::
ing layer and prior to consolidating to form the core, this ` alternate practice insures more uniform compacting throughout the thickness of the core prior to sintering.
, -3-.
., The following constitutes specific examples of the practice of the invention:
EXA~fPLE A:
Atomized steel powder of -lO0 mesh of the conventional composition identified as Ancorsteel lOOOB was blended with ferro-phosphorus powder, which had an average particle size of 13.5~m.
A blend of these powders, identified as Blend A2, was made to produce a 0.75 weight percent phosphorus-iron composition. The blend also contained 0.5% by weight zinc stearate, which was provided as a lubricant to facilitate ejection of the pressed powder material from the mold. From Blend A2 three powder charges of 24 grams, two of 12 grams and three of eight grams were - provided. From the 24-gram charge a single lamination in the form of a toroid was produced by double action pressing at 45 tons per square inch. The toroid had a nominal outside diameter after pressing of 3.75 centimeters and an inside diameter of 2.50 centimeters. The 12-gram and eight-gram charges were similarly pressed to form toroids. All of the toroids so produced were sintered for 60 minutes at 2300F in a vacuum furnace. A pressure jof 0.1 Torr (13.3 Pa) was maintained with a hydrogen atmosphere during sintering. The toroids were furnace cooled to room temperature. The characteristics of these samples are summarized in Table I.
117~ 6 TABLE I
Outside Inside Sample Weight ~iameter Diameter Thickness Density No. grams cm. cm. cm. g/cm3 3 1 23.7897 3.726 2.550 0.567 7.24
magnetic powder provide manufacturing cost advantages over the practice of constructing the core from laminations made from strip material. They provide, however, manufacturing disadvantages in that the sintering of ind;vidual laminations results in poor utilization of the sintering furnace. If the individual laminations are assembled prior to sintering this results in a cumbersome and expensive additional manufacturing operation in the overall practice.
. .: .
.. . .
. . .
., i~ ' ,.~ -1 ~
. . .
,:
.,. ~
., ., ili7Zt;)(~6 ., It is accordingly an object of the-invention to provide a method for manufacturing cores from ferromagnetic powder that provides, in combination, a metal core having the improved properties resulting from the use of ferromagnetic laminations , 5 achieved by an economic and efficient manufacturing practice.
This and other objects of the invention will be apparent from the following description and specific examples of the ~ practice of the invention.
'~ ~
The practice of the invention ~ s for the manufac-: 10 ture of a core for alternating current appl 00 ~ by placing a plurality of layers of the selected ferromagne~ ~wder into a container with each layer being separated one from the other.
` - When the desired number of layers, each one constituting a lamination in the final core, have been provided in the container tne powder is consolidated to form a core of intermediate density.
This core is then sintered in the conventional manner to achieve further densification. The ferromagnetic powder used in the practice of the invention may be an elemental ferromagnetic powder,a prealloyed ferromagnetic powder or a blend of ferro-, magnetic powder with one or more alloying elements. The powder may be made by conventional atomizing techniques, with examples thereof being atomized low carbon steel, atomized low carbon silicon-iron, atomized low carbon nickel-iron, or a blend of atomizing low carbon steel with nickel-molybdenum or cobalt powders singly or in combination. As is conventional practice a :
separating medium is provided between the layers or laminations in the practice of the invention. The separating medium may be in powder form or solid form, such as conventional alumina fiber sheet. If a separating medium in powder form is used such may be :' :.`
` -2-.
,~
'`
:
~::
1~7Z~)Q6 aluminum oxide, zirconium oxide or mixtures thereof. In an alternate procedure with respect to the invention each layer of ferromagnetic powder may be separately compacted within the container prior to consolidation to form the core.
More specifically with respect to the practice of the invention, in the manufacture of a core for magnetic applications the desired number of core laminations is determined. The total weight of the metal in powder form for the specific core would be divided into essentially equal portions in accordance with the ` 10 number of laminations required. Each of the portions would be introduced sequentially into a mold or die cavity having an internal cross section conforming substantially to that desired in - the core to be produced. The die would typically be provided with movable upper and lower die punches. Between each layer of ferro-magnetic material there would be provided an insulating medium : which may be solid or powder form as described hereinabove. When. ` all of the ferromagne~ic layers and insulating medium have been introduced to the die cavity, the upper and lower punches would be activated to press the powder material into a laminated core of~
,intermediate density. The density should be sufficient to permit handling particularly for conventional sintering. Sintering would be conducted in a furnace wherein the core would be moved through the furnace and heated to a temperature of, for example 2300F. This would then achieve a core with the final desired density. By using the alternate procedure of separately compacting each layer of ferromagnetic powder prior to introducing a succeed-!::
ing layer and prior to consolidating to form the core, this ` alternate practice insures more uniform compacting throughout the thickness of the core prior to sintering.
, -3-.
., The following constitutes specific examples of the practice of the invention:
EXA~fPLE A:
Atomized steel powder of -lO0 mesh of the conventional composition identified as Ancorsteel lOOOB was blended with ferro-phosphorus powder, which had an average particle size of 13.5~m.
A blend of these powders, identified as Blend A2, was made to produce a 0.75 weight percent phosphorus-iron composition. The blend also contained 0.5% by weight zinc stearate, which was provided as a lubricant to facilitate ejection of the pressed powder material from the mold. From Blend A2 three powder charges of 24 grams, two of 12 grams and three of eight grams were - provided. From the 24-gram charge a single lamination in the form of a toroid was produced by double action pressing at 45 tons per square inch. The toroid had a nominal outside diameter after pressing of 3.75 centimeters and an inside diameter of 2.50 centimeters. The 12-gram and eight-gram charges were similarly pressed to form toroids. All of the toroids so produced were sintered for 60 minutes at 2300F in a vacuum furnace. A pressure jof 0.1 Torr (13.3 Pa) was maintained with a hydrogen atmosphere during sintering. The toroids were furnace cooled to room temperature. The characteristics of these samples are summarized in Table I.
117~ 6 TABLE I
Outside Inside Sample Weight ~iameter Diameter Thickness Density No. grams cm. cm. cm. g/cm3 3 1 23.7897 3.726 2.550 0.567 7.24
2 11.8440 3.726 2.550 0.285 7.17
3 11.8691 3.724 2.550 0.284 7.22
4 7.9080 3.726 2.550 0.192 7.17
5 7.8882 3.725 2.550 0.189 7.21
6 7.8991 3.723 2.550 0.190 7.23 The toroid identified as Sample No. 1 produced from the 24-gram charge was prepared and magnetically tested. The toroids produced from the two 12-gram charges were combined and identified as Sample Nos. 2 and 3 to provide a two-lamination core with a - single air gap. l'he three toroids produced from the three eight-. gram charges were combined to provide a three-lamination core with two air gaps and`are identified as Samples Nos. 4, 5 and 6.
The cores were magnetically tested in identical fashion by placing them in fiber cases. The cores were uniformly wound with 100 turns primary and 100 turns secondary winding. The density of each core was determined from its weight and physical dimensions. The cross-sectional area for the voltage and ` induction level was determined from the core weight, mean magnetic path length and density in accordance with conventional practice.
The peak magnetizing force was determined by calculations from peak-peak voltage reading across a small series resistance. The cores were demagnetized using 60 Hertz voltages slowly decreased from a value well over the knee of the induction-peak magnetizing force curve to zero voltage. The core loss values were determined by testing the samples from the lowest to the highest induction levels using conventional ~S~ test procedures recommended for the purpose.
1~72~)6P6 Table II lists the 60 Hertz peak magnetizing force at induction levels of one to 10 kilogauss in one kilogauss increments.
TABLE II
60 HERTZ PEAK ~IAGI~ETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
Sample~lagnetizing Force-Oersteds No.1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
1 .969 1.607 2.563 3.889 5.865 8.441 11.552 15 045 19.635 26.138 2~3 .778 1.150 1.556 2.193 3.047 4.055 5.457 7.204 9.308 11.935 4,5,6 .663 0.946 1.229 1.543 2.002 3.576 3.366 4.144 5.202 6.566 Table III lists the 60 Hertz core loss in watts per pound at induction levels of one~to 10 kilogauss in one kilogauss increments.
TABLE III
AT VARIOUS INDUCTION LEVELS
.
Sample Core Loss - Watts Per pound No 1 KG 2 KG 3 KG4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
1 .0820 .274 .624 1.34 2.37 3.92 6.759.88 14.08 --2&3 .0603 .189 .395 0.713 1.28 2.02 3.054.45 6.78 9.27 4,5,6 .0486 .152 .304 0.520 0.891 1.33 1.92 2.71 3.74 5.07 EXAMPLE B:
The ferromagnetic powder, Blend A2 of Example A, was used with tabular alumina powder containing A12O3 in excess of 99.5% by weight with a particle size of -28/+48 mesh as a separating medium in powder form in accordance with the practice of the invention. Two 12-gram charges and three 8-gram charges were prepared from Blend A2. A core was produced using a mold of the dimensions described in Example A by providing a layer of 12 grams of Blend A 2 in the mold and 2.50 grams of the tabular 117Z(~Q6 alumina powder was placed on top of the layer of Blend A2. This operation was repeated and then the powder was pressed at 45 tons per square inch to form a double laminate core with alumina powder insulation between each layer. With a similar operation, a core of three eight-gram laminates separating the alumina powder was made. The two-laminate core is identified in Table IV as Sample No. 14 and the three-laminate core is identified as Sample No. 10. Both cores were vacuum sintered for 60 minutes at 2300F.
The density of both cores was determined to be 7.20 g/cm3. The cores were magnetically tested in the same manner as those of Example A. Table IV lists the 60 Hertz magnetizing force at induction levels of 1 to 10 kilogauss and in one kilogauss increments for each core.
TABLE IV
60 HERTZ PEAK MAGNETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
., .
SampleMagnetizing Force-Oersteds No.1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG10 KG
14 1.071 1.811 2.665 3.570 4.501 5.763 7.204 8.861 10.965 13.009 0.859 1.377 1.964 2.563 3.251 3.927 4.794 5.789 6.936 8.313 Table V lists the 60 Hertz core loss in watts per pound at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE V
`~ 60 HERTZ CORE-LOSS IN WATTS PER POUND
AT VARIOUS INDUCTION LEVELS
::`
~ Core Loss - Watts Per Pound ; Sample ` 30 No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG8 KG 9 KG 10 KG
14 .0885 .307 .658 1.22 1.92 2.82 3.965.97 7.89 10.31 .0634 .229 .485 0.899 1.38 2.00 2.783.7~ 4.87 6.82 .
~ .
. ., 117ZO~!6 It may be seen that at lower induction levels the magnetizing force and core losses of the cores of Example B
produced in accordance with the invention are relatively high;
however, at an induction level of about 5 kilogauss and greater these properties approach the values for the two- and three-laminate cores of Example A.
EXAMPLE C:
Blend A2 was used to produce cores having two laminations and cores having three laminations with the practice being identical to that described and used in Example ~, the only variation being tha~ in this example the insulating medium was alumina fiber sheet. The cores were sintered under conditions identical to that used and described with respect to Example B.
The density of the cores was 7.21 g/cm3. A one lamination core was also produced in accordance with this practice but without an insulating layer. This core is identified as Sample No. 2-0; the two-lamination core is identified as Sample No. 2-1 and the three-lamination core is identified as Sample No. 2-2-1. These three core samples were magnetically tested in the manner described with~
` respect to Example A. Table VI lists the 60 Hertz magnetizing force at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE VI
60 HERTZ MAGNETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
Sample Magnetizing Eorce-Oersteds No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
2-0 .983 1.58 2.53 3.93 5.75 8.36 11.43 14.94 19.92 25.80 2-1 .830 1.28 1.83 2.55 3.47 4.47 6.07 7.79 9.00 12.51 2-2~ 86 1.02 1.33 1.72 2.23 2.~3 3.55 4.44 5.48 6.90 117Z(~1~6 Table VII lists the 60 Hertz core loss in watts per pound at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE VII
AT VARIOUS INDUCTION LEVELS
Core Loss - Watts Per Pound Sample No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
2-0 .0657 .222 .515 1.31 2.34 3.88 6.50 9.61 13.91 19.35 2-1 .0674 .222 .473 0.890 1.47 2.28 3.40 4.89 7.35 9.96 2-2-1 .0471 .155 .314 0.536 0.986 1.46 2.08 2.90 3.97 5.34 It may be seen from the results in Tables VI and VII
that both the magnetizing force and core loss values are lower at all induction levels than for the cores of Example B and that they approach these values determined for the core samples of Example A.
_g _ .
The cores were magnetically tested in identical fashion by placing them in fiber cases. The cores were uniformly wound with 100 turns primary and 100 turns secondary winding. The density of each core was determined from its weight and physical dimensions. The cross-sectional area for the voltage and ` induction level was determined from the core weight, mean magnetic path length and density in accordance with conventional practice.
The peak magnetizing force was determined by calculations from peak-peak voltage reading across a small series resistance. The cores were demagnetized using 60 Hertz voltages slowly decreased from a value well over the knee of the induction-peak magnetizing force curve to zero voltage. The core loss values were determined by testing the samples from the lowest to the highest induction levels using conventional ~S~ test procedures recommended for the purpose.
1~72~)6P6 Table II lists the 60 Hertz peak magnetizing force at induction levels of one to 10 kilogauss in one kilogauss increments.
TABLE II
60 HERTZ PEAK ~IAGI~ETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
Sample~lagnetizing Force-Oersteds No.1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
1 .969 1.607 2.563 3.889 5.865 8.441 11.552 15 045 19.635 26.138 2~3 .778 1.150 1.556 2.193 3.047 4.055 5.457 7.204 9.308 11.935 4,5,6 .663 0.946 1.229 1.543 2.002 3.576 3.366 4.144 5.202 6.566 Table III lists the 60 Hertz core loss in watts per pound at induction levels of one~to 10 kilogauss in one kilogauss increments.
TABLE III
AT VARIOUS INDUCTION LEVELS
.
Sample Core Loss - Watts Per pound No 1 KG 2 KG 3 KG4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
1 .0820 .274 .624 1.34 2.37 3.92 6.759.88 14.08 --2&3 .0603 .189 .395 0.713 1.28 2.02 3.054.45 6.78 9.27 4,5,6 .0486 .152 .304 0.520 0.891 1.33 1.92 2.71 3.74 5.07 EXAMPLE B:
The ferromagnetic powder, Blend A2 of Example A, was used with tabular alumina powder containing A12O3 in excess of 99.5% by weight with a particle size of -28/+48 mesh as a separating medium in powder form in accordance with the practice of the invention. Two 12-gram charges and three 8-gram charges were prepared from Blend A2. A core was produced using a mold of the dimensions described in Example A by providing a layer of 12 grams of Blend A 2 in the mold and 2.50 grams of the tabular 117Z(~Q6 alumina powder was placed on top of the layer of Blend A2. This operation was repeated and then the powder was pressed at 45 tons per square inch to form a double laminate core with alumina powder insulation between each layer. With a similar operation, a core of three eight-gram laminates separating the alumina powder was made. The two-laminate core is identified in Table IV as Sample No. 14 and the three-laminate core is identified as Sample No. 10. Both cores were vacuum sintered for 60 minutes at 2300F.
The density of both cores was determined to be 7.20 g/cm3. The cores were magnetically tested in the same manner as those of Example A. Table IV lists the 60 Hertz magnetizing force at induction levels of 1 to 10 kilogauss and in one kilogauss increments for each core.
TABLE IV
60 HERTZ PEAK MAGNETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
., .
SampleMagnetizing Force-Oersteds No.1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG10 KG
14 1.071 1.811 2.665 3.570 4.501 5.763 7.204 8.861 10.965 13.009 0.859 1.377 1.964 2.563 3.251 3.927 4.794 5.789 6.936 8.313 Table V lists the 60 Hertz core loss in watts per pound at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE V
`~ 60 HERTZ CORE-LOSS IN WATTS PER POUND
AT VARIOUS INDUCTION LEVELS
::`
~ Core Loss - Watts Per Pound ; Sample ` 30 No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG8 KG 9 KG 10 KG
14 .0885 .307 .658 1.22 1.92 2.82 3.965.97 7.89 10.31 .0634 .229 .485 0.899 1.38 2.00 2.783.7~ 4.87 6.82 .
~ .
. ., 117ZO~!6 It may be seen that at lower induction levels the magnetizing force and core losses of the cores of Example B
produced in accordance with the invention are relatively high;
however, at an induction level of about 5 kilogauss and greater these properties approach the values for the two- and three-laminate cores of Example A.
EXAMPLE C:
Blend A2 was used to produce cores having two laminations and cores having three laminations with the practice being identical to that described and used in Example ~, the only variation being tha~ in this example the insulating medium was alumina fiber sheet. The cores were sintered under conditions identical to that used and described with respect to Example B.
The density of the cores was 7.21 g/cm3. A one lamination core was also produced in accordance with this practice but without an insulating layer. This core is identified as Sample No. 2-0; the two-lamination core is identified as Sample No. 2-1 and the three-lamination core is identified as Sample No. 2-2-1. These three core samples were magnetically tested in the manner described with~
` respect to Example A. Table VI lists the 60 Hertz magnetizing force at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE VI
60 HERTZ MAGNETIZING FORCE (Hp) IN OERSTEDS
AT VARIOUS INDUCTION LEVELS
Sample Magnetizing Eorce-Oersteds No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
2-0 .983 1.58 2.53 3.93 5.75 8.36 11.43 14.94 19.92 25.80 2-1 .830 1.28 1.83 2.55 3.47 4.47 6.07 7.79 9.00 12.51 2-2~ 86 1.02 1.33 1.72 2.23 2.~3 3.55 4.44 5.48 6.90 117Z(~1~6 Table VII lists the 60 Hertz core loss in watts per pound at induction levels of one to 10 kilogauss in one kilogauss increments for each core.
TABLE VII
AT VARIOUS INDUCTION LEVELS
Core Loss - Watts Per Pound Sample No. 1 KG 2 KG 3 KG 4 KG 5 KG 6 KG 7 KG 8 KG 9 KG 10 KG
2-0 .0657 .222 .515 1.31 2.34 3.88 6.50 9.61 13.91 19.35 2-1 .0674 .222 .473 0.890 1.47 2.28 3.40 4.89 7.35 9.96 2-2-1 .0471 .155 .314 0.536 0.986 1.46 2.08 2.90 3.97 5.34 It may be seen from the results in Tables VI and VII
that both the magnetizing force and core loss values are lower at all induction levels than for the cores of Example B and that they approach these values determined for the core samples of Example A.
_g _ .
Claims (6)
1. A method for making a metal core for alternating current applications from ferromagnetic powder, said method comprising placing a plurality of layers of said ferromagnetic powder into a container with a magnetic insulating medium provided between each layer separating each layer one from the other, thereafter pressing said powder to form a core of intermediate density and sintering said core to achieve further densification.
2. The method of claim 1 wherein said magnetic insulating medium is in powder form.
3. The method of claim 2 wherein said magnetic insulating medium in powder form is a powder selected from the group consisting of aluminum oxide, zirconium oxide and mixtures thereof.
4. The method of claim 1 wherein said magnetic insulating medium is fiber sheet.
5. The method of claim 4 wherein said magnetic insulating medium is alumina fiber sheet.
6. The method of claim 1 wherein each layer of said ferromagnetic powder is separately compacted within said container prior to pressing to form said core.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22782681A | 1981-01-23 | 1981-01-23 | |
| US227,826 | 1988-08-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1172006A true CA1172006A (en) | 1984-08-07 |
Family
ID=22854625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000390740A Expired CA1172006A (en) | 1981-01-23 | 1981-11-24 | Method for making cores for alternating current applications |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS57138118A (en) |
| CA (1) | CA1172006A (en) |
| FR (1) | FR2498500A1 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1074123A (en) * | 1963-07-26 | 1967-06-28 | Ass Elect Ind | Improvements relating to insulating/conductive composite refractory bodies |
| CA1036659A (en) * | 1973-09-11 | 1978-08-15 | Norman M. Pavlik | Molded magnetic cores utilizing cut steel particles |
| DE2850050C2 (en) * | 1978-11-16 | 1980-03-27 | Kurt 1000 Berlin Dinter | Method of manufacturing an electromagnetic platen |
-
1981
- 1981-11-24 CA CA000390740A patent/CA1172006A/en not_active Expired
-
1982
- 1982-01-18 JP JP586182A patent/JPS57138118A/en active Pending
- 1982-01-19 FR FR8200751A patent/FR2498500A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57138118A (en) | 1982-08-26 |
| FR2498500A1 (en) | 1982-07-30 |
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